Publications reported by three months

1.Bil M., Mrówka P., Kołbuk D., Święszkowski W., Multifunctional composite combining chitosan microspheres for drug delivery embedded in shape memory polyester-urethane matrix, Composites Science and Technology, ISSN: 0266-3538, DOI: 10.1016/j.compscitech.2020.108481, Vol.201, pp.108481-1-9, 2021
Bil M., Mrówka P., Kołbuk D., Święszkowski W., Multifunctional composite combining chitosan microspheres for drug delivery embedded in shape memory polyester-urethane matrix, Composites Science and Technology, ISSN: 0266-3538, DOI: 10.1016/j.compscitech.2020.108481, Vol.201, pp.108481-1-9, 2021

Abstract:
Multifunctional composite biomaterials (3b-PU/CH_M) consisting of chitosan microspheres (CH-M) that provide drug release functionality and crosslinked polyester-urethane (3b-PU) matrix responsible for shape memory properties were designed. A series of 3b-PU/CH_M bio-composites with varying weight fraction of CH-M (2.5, 5, and 10 wt %) embedded into 3b-PU matrix were synthesized. The ATR-FTIR confirmed the presence of covalent bonds between 3b-PU matrix and CH-M as well as enhanced hydrogen bonds interaction within bio-composites matrix in comparison to neat 3b-PU. It was found that CH-M had not impaired the shape memory properties of 3b-PU matrix and even slightly improved the shape recovery (Rr %). The Rr value increased to 100% for 3b-PU/CH 2.5% M and 3b-PU/CH 5% M after the third thermo-mechanical cycle. Moreover, the transition temperature (Ttrans) of shape recovery tailored to 30 °C by the chemical composition of the 3b-PU network was not affected by CH-M. Effectiveness of the application of the composites as a controlled drug delivery system at various pH conditions was confirmed in an in vitro release study of ciprofloxacin hydrochloride (Cpx-HCl) used as a model drug. In vitro biocompatibility studies revealed that the materials do not alter the cells' ability to proliferate and differentiate.

Keywords:
multifunctional composites, smart materials, shape memory behavior, multifunctional properties, drug release

2.Tauzowski P., Błachowski B., Lógó J., Topology optimization of elasto-plastic structures under reliability constraints: a first order approach, COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2020.106406, Vol.243, pp.106406-1-15, 2021
Tauzowski P., Błachowski B., Lógó J., Topology optimization of elasto-plastic structures under reliability constraints: a first order approach, COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2020.106406, Vol.243, pp.106406-1-15, 2021

Abstract:
The objective of this study is to propose a relatively simple and efficient method for reliability based topology optimization for structures made of elasto-plastic material. The process of determining the optimal topology of elasto-perfectly plastic structures is associated with the removal of material from the structure. Such a process leads to weakening of structural strength and stiffness causing at the same time increase the likelihood of structural failure. An important aspect of engineering design is to track this probability during the optimization process and not allow the structure safety to exceed a certain level specified by the designer. The purpose of this work is to combine the previously developed yield-limited topology optimization method with reliability analysis using first order approach. Effectiveness of the proposed methodology is demonstrated on benchmark problems proposed by Rozvany and Maute, and the elasto-plastic topology design of L-shape structure which is frequently used in different approaches for stress constrained topology optimization.

Keywords:
topology optimization, reliability analysis, elasto-plastic analysis

3.Richter Ł., Żuk P.J., Szymczak P., Paczesny J., Bąk K.M., Szymborski T., Garstecki P., Stone H.A., Hołyst R., Drummond C., Ions in an AC electric field: strong long-range repulsion between oppositely charged surfaces, PHYSICAL REVIEW LETTERS, ISSN: 0031-9007, DOI: 10.1103/PhysRevLett.125.056001, Vol.125, No.5, pp.056001-1-5, 2020
Richter Ł., Żuk P.J., Szymczak P., Paczesny J., Bąk K.M., Szymborski T., Garstecki P., Stone H.A., Hołyst R., Drummond C., Ions in an AC electric field: strong long-range repulsion between oppositely charged surfaces, PHYSICAL REVIEW LETTERS, ISSN: 0031-9007, DOI: 10.1103/PhysRevLett.125.056001, Vol.125, No.5, pp.056001-1-5, 2020

Abstract:
Two oppositely charged surfaces separated by a dielectric medium attract each other. In contrast we observe a strong repulsion between two plates of a capacitor that is filled with an aqueous electrolyte upon application of an alternating potential difference between the plates. This long-range force increases with the ratio of diffusion coefficients of the ions in the medium and reaches a steady state after a few minutes, which is much larger than the millisecond timescale of diffusion across the narrow gap. The repulsive force, an order of magnitude stronger than the electrostatic attraction observed in the same setup in air, results from the increase in osmotic pressure as a consequence of the field-induced excess of cations and anions due to lateral transport from adjacent reservoirs.

4.Han A., Byra M., Heba E., Andre M.P., Erdman J.W.Jr., Loomba R., Sirlin C.B., O'Brien W.D.Jr., Noninvasive diagnosis of nonalcoholic fatty liver disease and quantification of liver fat with radiofrequency ultrasound data using one-dimensional convolutional neural networks, Radiology, ISSN: 0033-8419, DOI: 10.1148/radiol.2020191160, Vol.295, No.2, pp.342-350, 2020
Han A., Byra M., Heba E., Andre M.P., Erdman J.W.Jr., Loomba R., Sirlin C.B., O'Brien W.D.Jr., Noninvasive diagnosis of nonalcoholic fatty liver disease and quantification of liver fat with radiofrequency ultrasound data using one-dimensional convolutional neural networks, Radiology, ISSN: 0033-8419, DOI: 10.1148/radiol.2020191160, Vol.295, No.2, pp.342-350, 2020

Abstract:
Background: Radiofrequency ultrasound data from the liver contain rich information about liver microstructure and composition. Deep learning might exploit such information to assess nonalcoholic fatty liver disease (NAFLD). Purpose: To develop and evaluate deep learning algorithms that use radiofrequency data for NAFLD assessment, with MRI-derived proton density fat fraction (PDFF) as the reference. Materials and Methods: A HIPAA-compliant secondary analysis of a single-center prospective study was performed for adult participants with NAFLD and control participants without liver disease. Participants in the parent study were recruited between February 2012 and March 2014 and underwent same-day US and MRI of the liver. Participants were randomly divided into an equal number of training and test groups. The training group was used to develop two algorithms via cross-validation: a classifier to diagnose NAFLD (MRI PDFF ≥ 5%) and a fat fraction estimator to predict MRI PDFF. Both algorithms used one-dimensional convolutional neural networks. The test group was used to evaluate the classifier for sensitivity, specificity, positive predictive value, negative predictive value, and accuracy and to evaluate the estimator for correlation, bias, limits of agreements, and linearity between predicted fat fraction and MRI PDFF. Results: A total of 204 participants were analyzed, 140 had NAFLD (mean age, 52 years ± 14 [standard deviation]; 82 women) and 64 were control participants (mean age, 46 years ± 21; 42 women). In the test group, the classifier provided 96% (95% confidence interval [CI]: 90%, 99%) (98 of 102) accuracy for NAFLD diagnosis (sensitivity, 97% [95% CI: 90%, 100%], 68 of 70; specificity, 94% [95% CI: 79%, 99%], 30 of 32; positive predictive value, 97% [95% CI: 90%, 99%], 68 of 70; negative predictive value, 94% [95% CI: 79%, 98%], 30 of 32). The estimator-predicted fat fraction correlated with MRI PDFF (Pearson r = 0.85). The mean bias was 0.8% (P = .08), and 95% limits of agreement were -7.6% to 9.1%. The predicted fat fraction was linear with an MRI PDFF of 18% or less (r = 0.89, slope = 1.1, intercept = 1.3) and nonlinear with an MRI PDFF greater than 18%. Conclusion: Deep learning algorithms using radiofrequency ultrasound data are accurate for diagnosis of nonalcoholic fatty liver disease and hepatic fat fraction quantification when other causes of steatosis are excluded.

5.Grzywacz H., Milczarek M., Jenczyk P., Dera W., Michałowski M., Jarząbek D.M., Quantitative measurement of nanofriction between PMMA thin films and various AFM probes, MEASUREMENT, ISSN: 0263-2241, DOI: 10.1016/j.measurement.2020.108267, Vol.168, pp.108267-1-13, 2020
Grzywacz H., Milczarek M., Jenczyk P., Dera W., Michałowski M., Jarząbek D.M., Quantitative measurement of nanofriction between PMMA thin films and various AFM probes, MEASUREMENT, ISSN: 0263-2241, DOI: 10.1016/j.measurement.2020.108267, Vol.168, pp.108267-1-13, 2020

Abstract:
This study reports the quantitative, precise and accurate results of nanoscale friction measurements with the use of an Atomic Force Microscope calibrated with a precise nanoforce sensor. For this purpose, three samples of spin-coated thin Polymethylmethacrylate (PMMA) films were prepared with the following thicknesses: 235, 343, and 513 nm. Three different AFM probes were used for the friction measurements: with diamond-like carbon (DLC) tip with a small (15 nm) or big (2 µm) tip radius, and a reference silicon tip with a small (8 nm) radius. The results show that in all of the studied cases, the coefficient of friction strongly depends on the applied load, being much higher for a lower load. Furthermore, a strong relation of the friction force on the cantilever's geometry, the scanning velocity, and the film thickness was observed.

Keywords:
lateral force microscopy, friction, thin PMMA films, atomic force microscope, DLC coatings, adhesion

6.Yang H., Akinoglu E.M., Guo L., Jin M., Zhou G., Giersig M., Shui L., Mulvaney P., A PTFE helical capillary microreactor for the high throughput synthesis of monodisperse silica particles, Chemical Engineering Journal, ISSN: 1385-8947, DOI: 10.1016/j.cej.2020.126063, Vol.401, pp.126063-1-29, 2020
Yang H., Akinoglu E.M., Guo L., Jin M., Zhou G., Giersig M., Shui L., Mulvaney P., A PTFE helical capillary microreactor for the high throughput synthesis of monodisperse silica particles, Chemical Engineering Journal, ISSN: 1385-8947, DOI: 10.1016/j.cej.2020.126063, Vol.401, pp.126063-1-29, 2020

Abstract:
We propose a simple and inexpensive SiO2 submicron particle synthesis method based on a PTFE helical capillary microreactor. The device is based on Dean flow mediated, ultrafast mixing of two liquid phases in a microfluidic spiral pipe. Excellent control of particle size between 100 nm and 600 nm and narrow polydispersity can be achieved by controlling the device and process parameters. Numerical simulations are performed to determine the optimal device dimensions. In the mother liquor the silica particles exhibit zeta potentials < -60 mV, rendering them very stable even at high particle volume fractions. The current device typically produces around 0.234 g/h of the silica particles.

Keywords:
SiO2 particle synthesis, continuous flow synthesis, helical capillary microreactor

7.Gupta A., Żuk P.J., Stone H.A., Charging dynamics of overlapping double layers in a cylindrical nanopore, PHYSICAL REVIEW LETTERS, ISSN: 0031-9007, DOI: 10.1103/PhysRevLett.125.076001, Vol.125, No.7, pp.076001-1-6, 2020
Gupta A., Żuk P.J., Stone H.A., Charging dynamics of overlapping double layers in a cylindrical nanopore, PHYSICAL REVIEW LETTERS, ISSN: 0031-9007, DOI: 10.1103/PhysRevLett.125.076001, Vol.125, No.7, pp.076001-1-6, 2020

Abstract:
The charging of electrical double layers inside a cylindrical pore has applications to supercapacitors, batteries, desalination and biosensors. The charging dynamics in the limit of thin double layers, i.e., when the double layer thickness is much smaller than the pore radius, is commonly described using an effective RC transmission line circuit. Here, we perform direct numerical simulations (DNS) of the Poisson-Nernst-Planck equations to study the double layer charging for the scenario of overlapping double layers, i.e., when the double layer thickness is comparable to the pore radius. We develop an analytical model that accurately predicts the results of DNS. Also, we construct a modified effective circuit for the overlapping double layer limit, and find that the modified circuit is identical to the RC transmission line but with different values and physical interpretation of the capacitive and resistive elements. In particular, the effective surface potential is reduced, the capacitor represents a volumetric current source, and the charging timescale is weakly dependent on the ratio of the pore radius and the double layer thickness.

8.Darban H., Luciano R., Caporale A., Fabbrocino F., Higher modes of buckling in shear deformable nanobeams, International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2020.103338, Vol.154, pp.103338-1-18, 2020
Darban H., Luciano R., Caporale A., Fabbrocino F., Higher modes of buckling in shear deformable nanobeams, International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2020.103338, Vol.154, pp.103338-1-18, 2020

Abstract:
The size-dependent buckling instability of shear deformable nanobeams rested on a two-parameter elastic foundation is studied through the stress-driven nonlocal theory of elasticity and the kinematic assumptions of the Timoshenko beam theory. The small-scale size effects are taken into account by nonlocal constitutive relationships, which define the strains at each point as integral convolutions in terms of the stresses in all the points and a kernel. In this manner, the nonlocal elasticity formulation is well-posed and does not include inconsistencies usually arising using other nonlocal models. The size-dependent governing differential equations in terms of the transverse displacement and the cross-sectional rotation are decoupled, and closed form solutions are presented for the displacement functions. Proper boundary conditions are imposed and the buckling problem is reduced to finding roots of a determinant of a matrix, whose elements are given explicitly for different classical edge conditions. The closed form treatment of the problem avoids the numerical instabilities usually occurring within numerical techniques, and allows to find also higher buckling loads and shape modes. Several nanobeams rested on the Winkler or Pasternak elastic foundations and characterized by different boundary conditions, shear deformability, and nonlocality are considered and the critical loads and shape modes are presented, including those for the higher modes of buckling. Excellent agreements are found with the available approximate numerical results in the literature and novel insightful findings are presented and discussed, which are in accordance with experimental observations.

Keywords:
nanobeam, buckling, elastic foundation, closed form solution, nonlocal elasticity, size effect

9.Zieliński T.G., Opiela K.C., Pawłowski P., Dauchez N., Boutin T., Kennedy J., Trimble D., Rice H., Van Damme B., Hannema G., Wróbel R., Kim S., Ghaffari Mosanenzadeh S., Fang N.X., Yang J., Briere de La Hosseraye B., Hornikx M.C.J., Salze E., Galland M.-A., Boonen R., Carvalho de Sousa A., Deckers E., Gaborit M., Groby J.-P., Reproducibility of sound-absorbing periodic porous materials using additive manufacturing technologies: round robin study, Additive Manufacturing, ISSN: 2214-8604, DOI: 10.1016/j.addma.2020.101564, Vol.36, pp.101564-1-24, 2020
Zieliński T.G., Opiela K.C., Pawłowski P., Dauchez N., Boutin T., Kennedy J., Trimble D., Rice H., Van Damme B., Hannema G., Wróbel R., Kim S., Ghaffari Mosanenzadeh S., Fang N.X., Yang J., Briere de La Hosseraye B., Hornikx M.C.J., Salze E., Galland M.-A., Boonen R., Carvalho de Sousa A., Deckers E., Gaborit M., Groby J.-P., Reproducibility of sound-absorbing periodic porous materials using additive manufacturing technologies: round robin study, Additive Manufacturing, ISSN: 2214-8604, DOI: 10.1016/j.addma.2020.101564, Vol.36, pp.101564-1-24, 2020

Abstract:
The purpose of this work is to check if additive manufacturing technologies are suitable for reproducing porous samples designed for sound absorption. The work is an inter-laboratory test, in which the production of samples and their acoustic measurements are carried out independently by different laboratories, sharing only the same geometry codes describing agreed periodic cellular designs. Different additive manufacturing technologies and equipment are used to make samples. Although most of the results obtained from measurements performed on samples with the same cellular design are very close, it is shown that some discrepancies are due to shape and surface imperfections, or microporosity, induced by the manufacturing process. The proposed periodic cellular designs can be easily reproduced and are suitable for further benchmarking of additive manufacturing techniques for rapid prototyping of acoustic materials and metamaterials.

Keywords:
porous materials, designed periodicity, additive manufacturing, sound absorption

10.Darban H., Fabbrocino F., Luciano R., Size-dependent linear elastic fracture of nanobeams, International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2020.103381, Vol.157, pp.103381-1-13, 2020
Darban H., Fabbrocino F., Luciano R., Size-dependent linear elastic fracture of nanobeams, International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2020.103381, Vol.157, pp.103381-1-13, 2020

Abstract:
A nonlocal linear elastic fracture formulation is presented based on a discrete layer approach and an interface model to study cracked nanobeams. The formulation uses the stress-driven nonlocal theory of elasticity to account for the size-dependency in the constitutive equations, and the Bernoulli-Euler beam theory to define the kinematic field. Two fundamental mode I and mode II fracture nanospecimens with applications in Engineering Science are studied to reveal principal characteristics of the linear elastic fracture of beams at nanoscale. The domains are discretized both through the transverse and longitudinal directions and the field variables are derived by solving systems of the nonlocal equilibrium equations subjected to the variationally consistent and constitutive boundary and continuity conditions. The energy release rates of the fracture nanospecimens are calculated both from the global energy consideration and from the localized fields at the tip of the crack, i.e. the cohesive forces and the displacement jumps. The results are shown to be the same, proving the capability of the interface model to predict localized fields at the crack tip which are important for the cohesive fracture problems. It is found that the nanospecimens with higher nonlocality have higher fracture resistance and load bearing capacity due to higher energy absorptions and lower energy release rates. The crack propagation in the nanospecimens are also studied and load-displacement curves are presented. The nonlocality considerably increases the stiffness of the initial linear response of the nanospecimens. The fracture model is also able to capture the non-linear post-peak response and the unstable crack propagation, the snap-back instability, which is more intense for nanospecimens with higher nonlocality.

Keywords:
cracked nanobeams, nonlocal fracture, energy release rate, cohesive, crack propagation

11.Marszałek A., Burczyński T., Ordered fuzzy random variable: definition and the concept of normality, INFORMATION SCIENCES, ISSN: 0020-0255, DOI: 10.1016/j.ins.2020.08.120, pp.1-12, 2020
Marszałek A., Burczyński T., Ordered fuzzy random variable: definition and the concept of normality, INFORMATION SCIENCES, ISSN: 0020-0255, DOI: 10.1016/j.ins.2020.08.120, pp.1-12, 2020

Abstract:
The concept of fuzzy random variable combines two sources of uncertainty: randomness and fuzziness, whereas the model of ordered fuzzy numbers provides a representation of inaccurate quantitative data, and is an alternative to the standard fuzzy numbers model proposed by Zadeh. This paper develops the model of ordered fuzzy numbers by defining the concept of fuzzy random variables for these numbers, called further ordered fuzzy random variables. Thanks to the well-defined arithmetic of ordered fuzzy numbers (existence of neutral and opposite elements) and the introduced ordered fuzzy random variables; it becomes possible to construct fully fuzzy stochastic time series models such as e.g., the autoregressive model or the GARCH model in the form of classical equations, which can be estimated using the least-squares or the maximum likelihood method. Furthermore, the concept of normality of ordered fuzzy random variables and the method to generate pseudo-random ordered fuzzy variables with normal distribution are introduced.

Keywords:
ordered fuzzy numbers, fuzzy random variables, ordered fuzzy random variables, normal ordered fuzzy random variable

12.Kowalczyk-Gajewska K., Maździarz M., Elastic properties of nanocrystalline materials of hexagonal symmetry: the core-shell model and atomistic estimates, International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2020.103393, Vol.157, pp.103393-1-21, 2020
Kowalczyk-Gajewska K., Maździarz M., Elastic properties of nanocrystalline materials of hexagonal symmetry: the core-shell model and atomistic estimates, International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2020.103393, Vol.157, pp.103393-1-21, 2020

Abstract:
Anisotropic core-shell model of a nano-grained polycrystal is extended to estimate the effective elastic stiffness of several metals of hexagonal crystal lattice symmetry. In the approach the bulk nanocrystalline material is described as a two-phase medium with different properties for a grain boundary zone and a grain core. While the grain core is anisotropic, the boundary zone is isotropic and has a thickness defined by the cutoff radius of a corresponding atomistic potential for the considered metal. The predictions of the proposed mean-field model are verified with respect to simulations performed with the use of the Large-scale Atomic/Molecular Massively Parallel Simulator, the Embedded Atom Model, and the molecular statics method. The effect of the grain size on the overall elastic moduli of nanocrystalline material with random distribution of orientations is analyzed.

Keywords:
molecular statics, elasticity, polycrystal, effective medium, hexagonal symmetry

13.Jóźwiak-Niedźwiedzka D., Antolik A., Dziedzic K., Gméling K., Bogusz K., Laboratory investigations on fine aggregates used for concrete pavements due to the risk of ASR, Road Materials and Pavement Design, ISSN: 1468-0629, DOI: 10.1080/14680629.2020.1796767, pp.1-13, 2020
Jóźwiak-Niedźwiedzka D., Antolik A., Dziedzic K., Gméling K., Bogusz K., Laboratory investigations on fine aggregates used for concrete pavements due to the risk of ASR, Road Materials and Pavement Design, ISSN: 1468-0629, DOI: 10.1080/14680629.2020.1796767, pp.1-13, 2020

Abstract:
The assessment of the aggregate suitability for concrete pavements applies mainly to coarse aggregate. However, even fine aggregate can significantly affect the long-term durability of concrete when it is susceptible to alkali-silica reaction (ASR). The sustainable use of available fine aggregates for the production of concrete, while reducing the effects of ASR, requires special preventive measures. The paper proposed different procedures to determine the chemical composition of aggregate and the related ASR risk. The study covers various properties of natural fine aggregates from glacial deposits. The experiments included determination of chemical composition by prompt gamma activation analysis (PGAA), quantitative mineralogical characterisation on thin sections using digital image procedure (DIP) and expansion measurements in mortar bar test (MBT). The strong correlation of sand origin and its susceptibility to ASR was observed. Content of micro- and cryptocrystalline quartz in siliceous sand was found to have a crucial effect on its performance in AMBT.

Keywords:
fine aggregate, alkali-silica reaction, mineral composition, prompt gamma activation analysis, digital image procedure, glacial deposit

14.Gabriele V.R., Shvonski A., Hoffman C.S., Giersig M., Herczynski A., Naughton M.J., Kempa K., Towards spectrally selective catastrophic response, PHYSICAL REVIEW E, ISSN: 2470-0045, DOI: 10.1103/PhysRevE.101.062415, Vol.101, pp.062415-1-6, 2020
Gabriele V.R., Shvonski A., Hoffman C.S., Giersig M., Herczynski A., Naughton M.J., Kempa K., Towards spectrally selective catastrophic response, PHYSICAL REVIEW E, ISSN: 2470-0045, DOI: 10.1103/PhysRevE.101.062415, Vol.101, pp.062415-1-6, 2020

Abstract:
We study the large-amplitude response of classical molecules to electromagnetic radiation, showing the universality of the transition from linear to nonlinear response and breakup at sufficiently large amplitudes. We demonstrate that a range of models, from the simple harmonic oscillator to the successful Peyrard-Bishop-Dauxois type models of DNA, which include realistic effects of the environment (including damping and dephasing due to thermal fluctuations), lead to characteristic universal behavior: formation of domains of dissociation in driving force amplitude-frequency space, characterized by the presence of local boundary minima. We demonstrate that by simply following the progression of the resonance maxima in this space, while gradually increasing intensity of the radiation, one must necessarily arrive at one of these minima, i.e., a point where the ultrahigh spectral selectivity is retained. We show that this universal property, applicable to other oscillatory systems, is a consequence of the fact that these models belong to the fold catastrophe universality class of Thom's catastrophe theory. This in turn implies that for most biostructures, including DNA, high spectral sensitivity near the onset of the denaturation processes can be expected. Such spectrally selective molecular denaturation could find important applications in biology and medicine.

15.Mieloch A.A., Żurawek M., Giersig M., Rozwadowska N., Rybka J.D., Bioevaluation of superparamagnetic iron oxide nanoparticles (SPIONs) functionalized with dihexadecyl phosphate (DHP), Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-020-59478-2, Vol.10, pp.2725-1-11, 2020
Mieloch A.A., Żurawek M., Giersig M., Rozwadowska N., Rybka J.D., Bioevaluation of superparamagnetic iron oxide nanoparticles (SPIONs) functionalized with dihexadecyl phosphate (DHP), Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-020-59478-2, Vol.10, pp.2725-1-11, 2020

Abstract:
Superparamagnetic iron oxide nanoparticles (SPIONs) have been investigated for wide variety of applications. Their unique properties render them highly applicable as MRI contrast agents, in magnetic hyperthermia or targeted drug delivery. SPIONs surface properties affect a whole array of parameters such as: solubility, toxicity, stability, biodistribution etc. Therefore, progress in the field of SPIONs surface functionalization is crucial for further development of therapeutic or diagnostic agents. In this study, SPIONs were synthesized by thermal decomposition of iron (III) acetylacetonate Fe(acac)3 and functionalized with dihexadecyl phosphate (DHP) via phase transfer. Bioactivity of the SPION-DHP was assessed on SW1353 and TCam-2 cancer derived cell lines. The following test were conducted: cytotoxicity and proliferation assay, reactive oxygen species (ROS) assay, SPIONs uptake (via Iron Staining and ICP-MS), expression analysis of the following genes: alkaline phosphatase (ALPL); ferritin light chain (FTL); serine/threonine protein phosphatase 2A (PP2A); protein tyrosine phosphatase non-receptor type 11 (PTPN11); transferrin receptor 1 (TFRC) via RT-qPCR. SPION-DHP nanoparticles were successfully obtained and did not reveal significant cytotoxicity in the range of tested concentrations. ROS generation was elevated, however not correlated with the concentrations. Gene expression profile was slightly altered only in SW1353 cells.

16.Byra M., Jarosik P., Szubert A., Galperine M., Ojeda-Fournier H., Olson L., O'Boyle M., Comstock Ch., Andre M., Breast mass segmentation in ultrasound with selective kernel U-Net convolutional neural network, Biomedical Signal Processing and Control, ISSN: 1746-8094, DOI: 10.1016/j.bspc.2020.102027, Vol.61, pp.102027-1-10, 2020
Byra M., Jarosik P., Szubert A., Galperine M., Ojeda-Fournier H., Olson L., O'Boyle M., Comstock Ch., Andre M., Breast mass segmentation in ultrasound with selective kernel U-Net convolutional neural network, Biomedical Signal Processing and Control, ISSN: 1746-8094, DOI: 10.1016/j.bspc.2020.102027, Vol.61, pp.102027-1-10, 2020

Abstract:
In this work, we propose a deep learning method for breast mass segmentation in ultrasound (US). Variations in breast mass size and image characteristics make the automatic segmentation difficult. To addressthis issue, we developed a selective kernel (SK) U-Net convolutional neural network. The aim of the SKswas to adjust network's receptive fields via an attention mechanism, and fuse feature maps extractedwith dilated and conventional convolutions. The proposed method was developed and evaluated usingUS images collected from 882 breast masses. Moreover, we used three datasets of US images collectedat different medical centers for testing (893 US images). On our test set of 150 US images, the SK-U-Netachieved mean Dice score of 0.826, and outperformed regular U-Net, Dice score of 0.778. When evaluatedon three separate datasets, the proposed method yielded mean Dice scores ranging from 0.646 to 0.780. Additional fine-tuning of our better-performing model with data collected at different centers improvedmean Dice scores by ~6%. SK-U-Net utilized both dilated and regular convolutions to process US images. We found strong correlation, Spearman's rank coefficient of 0.7, between the utilization of dilated convo-lutions and breast mass size in the case of network's expansion path. Our study shows the usefulness ofdeep learning methods for breast mass segmentation. SK-U-Net implementation and pre-trained weightscan be found at github.com/mbyr/bus_seg.

Keywords:
attention mechanism, breast mass segmentation, convolutional neural networks, deep learning, receptive field, ultrasound imaging

17.Byra M., Dobruch-Sobczak K., Klimonda Z., Piotrzkowska-Wróblewska H., Litniewski J., Early prediction of response to neoadjuvant chemotherapy in breast cancer sonography using Siamese convolutional neural networks, IEEE Journal of Biomedical and Health Informatics, ISSN: 2168-2208, DOI: 10.1109/JBHI.2020.3008040, pp.1-8, 2020
Byra M., Dobruch-Sobczak K., Klimonda Z., Piotrzkowska-Wróblewska H., Litniewski J., Early prediction of response to neoadjuvant chemotherapy in breast cancer sonography using Siamese convolutional neural networks, IEEE Journal of Biomedical and Health Informatics, ISSN: 2168-2208, DOI: 10.1109/JBHI.2020.3008040, pp.1-8, 2020

Abstract:
Early prediction of response to neoadjuvant chemotherapy (NAC) in breast cancer is crucial for guiding therapy decisions. In this work, we propose a deep learning based approach for the early NAC response prediction in ultrasound (US) imaging. We used transfer learning with deep convolutional neural networks (CNNs) to develop the response prediction models. The usefulness of two transfer learning techniques was examined. First, a CNN pre-trained on the ImageNet dataset was utilized. Second, we applied double transfer learning, the CNN pre-trained on the ImageNet dataset was additionally fine-tuned with breast mass US images to differentiate malignant and benign lesions. Two prediction tasks were investigated. First, a L1 regularized logistic regression prediction model was developed based on generic neural features extracted from US images collected before the chemotherapy (a priori prediction). Second, Siamese CNNs were used to quantify differences between US images collected before the treatment and after the first and second course of NAC. The proposed methods were evaluated using US data collected from 39 tumors. The better performing deep learning models achieved areas under the receiver operating characteristic curve of 0.797 and 0.847 in the case of the a priori prediction and the Siamese model, respectively. The proposed approach was compared with a
method based on handcrafted morphological features. Our study presents the feasibility of using transfer learning with CNNs for the NAC response prediction in US imaging.

Keywords:
breast cancer, deep learning, neoadjuvant chemotherapy, Siamese convolutional neural networks, ultrasound imaging

18.Ghalya N., Sellier A., Ekiel-Jeżewska M.L., Feuillebois F., Effective viscosity of a dilute homogeneous suspension of spheres in Poiseuille flow between parallel slip walls, JOURNAL OF FLUID MECHANICS, ISSN: 0022-1120, DOI: 10.1017/jfm.2020.429, Vol.899, pp.A13-1-36, 2020
Ghalya N., Sellier A., Ekiel-Jeżewska M.L., Feuillebois F., Effective viscosity of a dilute homogeneous suspension of spheres in Poiseuille flow between parallel slip walls, JOURNAL OF FLUID MECHANICS, ISSN: 0022-1120, DOI: 10.1017/jfm.2020.429, Vol.899, pp.A13-1-36, 2020

Abstract:
For flows in microchannels, a slip on the walls may be efficient in reducing viscous dissipation. A related issue, addressed in this article, is to decrease the effective viscosity of a dilute monodisperse suspension of spheres in Poiseuille flow by using two parallel slip walls. Extending the approach developed for no-slip walls in Feuillebois et al. (J. Fluid Mech., vol. 800, 2016, pp. 111–139), a formal expression is obtained for the suspension intrinsic viscosity [μ] solely in terms of a stresslet component and a quadrupole component exerted on a single freely suspended sphere. In the calculation of [μ], the hydrodynamic interactions between a sphere and the slip walls are approximated using either the nearest wall model or the wall-superposition model. Both the stresslet and quadrupole are derived and accurately calculated using bipolar coordinates. Results are presented for [μ] in terms of H/(2a) and ˜λ = λ/a ≤ 1, where H is the gap between walls, a is the sphere radius and λ is the wall slip length using the Navier slip boundary condition. As compared with the no-slip case, the intrinsic viscosity strongly depends on ˜λ for given H/(2a), especially for small H/(2a). For example, in the very confined case H/(2a) = 2 (a lower bound found for practical validity of single-wall models) and for ˜λ = 1, the intrinsic viscosity is three times smaller than for a suspension bounded by no-slip walls and five times smaller than for an unbounded suspension (Einstein, Ann. Phys., vol. 19, 1906, pp. 289–306). We also provide a handy formula fitting our results for [μ] in the entire range 2 ≤ H/(2a) ≤ 100 and ˜λ ≤ 1.

Keywords:
complex fluids, low-Reynolds-number flows

19.Hat B., Jaruszewicz-Błońska J., Lipniacki T., Model-based optimization of combination protocols for irradiation-insensitive cancers, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-020-69380-6, Vol.10, pp.12652-1-14, 2020
Hat B., Jaruszewicz-Błońska J., Lipniacki T., Model-based optimization of combination protocols for irradiation-insensitive cancers, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-020-69380-6, Vol.10, pp.12652-1-14, 2020

Abstract:
Alternations in the p53 regulatory network may render cancer cells resistant to the radiation-induced apoptosis. In this theoretical study we search for the best protocols combining targeted therapy with radiation to treat cancers with wild-type p53, but having downregulated expression of PTEN or overexpression of Wip1 resulting in resistance to radiation monotherapy. Instead of using the maximum tolerated dose paradigm, we exploit stochastic computational model of the p53 regulatory network to calculate apoptotic fractions for both normal and cancer cells. We consider combination protocols, with irradiations repeated every 12, 18, 24, or 36 h to find that timing between Mdm2 inhibitor delivery and irradiation significantly influences the apoptotic cell fractions. We assume that uptake of the inhibitor is higher by cancer than by normal cells and that cancer cells receive higher irradiation doses from intersecting beams. These two assumptions were found necessary for the existence of protocols inducing massive apoptosis in cancer cells without killing large fraction of normal cells neighboring tumor. The best found protocols have irradiations repeated every 24 or 36 h with two inhibitor doses per irradiation cycle, and allow to induce apoptosis in more than 95% of cancer cells, killing less than 10% of normal cells.

20.Jóźwiak-Niedźwiedzka D., Fantilli A.P., Wool-reinforced cement based composites, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13163590, Vol.13, No.16, pp.3590-1-13, 2020
Jóźwiak-Niedźwiedzka D., Fantilli A.P., Wool-reinforced cement based composites, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13163590, Vol.13, No.16, pp.3590-1-13, 2020

Abstract:
In this paper, an overview of the latest research activities in the field of cement-based composites incorporating sheep wool reinforcement is presented. First, the characteristics of this type of natural fibre are described. Then, the current use of sheep wool fibres in cement-based composites is discussed. The research problems regarding the properties of cement matrix composites reinforced with sheep wool are divided into four groups: thermal and acoustic properties, mechanical behavior, durability issues, and microstructure aspects. The latter two groups are analysed separately, because both durability and microstructure are of particular importance for future applications of wool reinforcement. Finally, the main directions of future researches are presented.

Keywords:
natural fibres, sheep wool fibres, mechanical properties, durability, microstructure

21.Lewandowski-Szewczyk M.J., Stupkiewicz S., Non-standard contact conditions in generalized continua: microblock contact model for a Cosserat body, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2020.07.001, Vol.202, pp.881-894, 2020
Lewandowski-Szewczyk M.J., Stupkiewicz S., Non-standard contact conditions in generalized continua: microblock contact model for a Cosserat body, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2020.07.001, Vol.202, pp.881-894, 2020

Abstract:
Generalized continuum theories involve non-standard boundary conditions that are associated with the additional kinematic variables introduced in those theories, e.g., higher gradients of the displacement field or additional kinematic degrees of freedom. Accordingly, formulation of a contact problem for such a continuum necessarily requires that adequate contact conditions are formulated for the additional kinematic variables and/or for the respective generalized tractions. In this paper, we address several related open problems, namely, how to enhance the classic contact conditions to include the effects of the additional kinematic variables, how to link the enhanced contact model to the underlying microstructure of the solid, and how to do it in a consistent manner. As a first step towards a new class of contact models for generalized continua, a microblock contact model is derived for a Cosserat solid based on simple micromechanical considerations. To illustrate the non-trivial effects introduced by the non-standard boundary conditions, the problem of compression of an infinite strip with nonaligned microblocks is considered, and the analytical solution is derived for the corresponding boundary layers. A Hertz-like contact problem is also solved numerically with the focus on non-standard features of the solution and on the related size effects.

Keywords:
microstructure, contact problems, size effects, boundary layers, Cosserat continuum

22.Ceroni F., Darban H., Luciano R., Analysis of bond behavior of injected anchors in masonry elements by means of finite element modeling, COMPOSITE STRUCTURES, ISSN: 0263-8223, DOI: 10.1016/j.compstruct.2020.112099, Vol.241, pp.112099-1-18, 2020
Ceroni F., Darban H., Luciano R., Analysis of bond behavior of injected anchors in masonry elements by means of finite element modeling, COMPOSITE STRUCTURES, ISSN: 0263-8223, DOI: 10.1016/j.compstruct.2020.112099, Vol.241, pp.112099-1-18, 2020

Abstract:
Injected anchors made of steel bars embedded in masonry elements by means of cement-based grout represented in the past a wide solution for avoiding out-of-plane mechanisms. Corrosion phenomena in steel bars reduced the effectiveness of such type of intervention over time. Innovative materials, as the Fiber Reinforced Plastic ones, can represent a suitable alternative to increase durability and performance of injected anchors. Since the effectiveness of injected anchors is strictly related to bond behaviour along both the bar-grout and the grout-masonry interfaces, a detailed analysis by means of a Finite Element model was developed for different types of bars embedded in masonry elements. The numerical model was firstly calibrated on some experimental results of pull-out tests available in literature and, then, is used for investigating the effects of several parameters on both local and global behaviour. Load-displacement curves and local distributions of shear stresses are examined in detail. The numerical analyses evidenced that the maximum tensile force in the anchor mainly depends on the shear strength of the bar-grout and the grout-masonry interfaces and on the embedded length, but for very long embedded length, it can be limited by the tensile failure in the anchor or in the masonry.

Keywords:
masonry, FRP bars, injected anchors, bond, pull-out test, FE model

23.Pisarski D., Szmidt T., Konowrocki R., Decentralized semi‐active structural vibration control based on optimal system modelling, STRUCTURAL CONTROL AND HEALTH MONITORING, ISSN: 1545-2255, DOI: 10.1002/stc.2624, Vol.27, No.11, pp.e2624-1-20, 2020
Pisarski D., Szmidt T., Konowrocki R., Decentralized semi‐active structural vibration control based on optimal system modelling, STRUCTURAL CONTROL AND HEALTH MONITORING, ISSN: 1545-2255, DOI: 10.1002/stc.2624, Vol.27, No.11, pp.e2624-1-20, 2020

Abstract:
The problem of decentralized semi‐active stabilization of vibration of a beam structure is studied. The decentralized controller's architecture is attained by means of optimal system modelling. In this approach, based on a specially designed and optimized set of basis functions, the solution to the continuous Euler-Bernoulli beam equation is approximated by a discrete system, where the mass and stiffness matrices ensure that the assumed stabilizing control law can be operated by using solely the local state information. The performance of the method is examined through numerical experiments for a series of free‐vibration scenarios with comparison to competitive decentralized and centralized control strategies. The performance impact of the selection of the parameters of the optimal system model is also studied. The designed method allows practical modular arrangements of the control system and is applicable to large‐scale structures.

Keywords:
bilinear system, decentralized control, polynomial basis, semi-active control, stabilization

24.Zawidzki M., Szklarski J., Multi-objective optimization of the floor plan of a single story family house considering position and orientation, Advances in Engineering Software, ISSN: 0965-9978, DOI: 10.1016/j.advengsoft.2019.102766, Vol.141, pp.1-16, 2020
Zawidzki M., Szklarski J., Multi-objective optimization of the floor plan of a single story family house considering position and orientation, Advances in Engineering Software, ISSN: 0965-9978, DOI: 10.1016/j.advengsoft.2019.102766, Vol.141, pp.1-16, 2020

Abstract:
Improving the architectural layout for diverse objectives using rigorous mathematical optimization methods gradually receives more attention by the researchers. Such optimization however, is usually reduced to a much simpler and relatively well-defined problem such as: facility layout optimization, quadratic assignment problem, rectangle partitioning. Nonetheless, architects are usually skeptical about such approaches since they produce solutions which lack certain architectural qualities. This paper proposes a framework where architectural functional layout (FL) is optimized for the following objectives: functionality (defined by users), insolation (calculated according to geographical conditions), outside view attractiveness (assessed on-site) and external noise (measured on-site). Incorporating the latter two and simultaneous optimization of FLs for objectives related specifically to the site: position and orientation are the novel contributions of this paper. Firstly, a set of candidate FLs is generated, next they are evaluated for optimal location and orientation on a given site. Optimality is conceived here as maximization of real-valued objective function combining: user's satisfaction level of the outside views, shielding from external noise, and insolation
preference. The importance of these factors for each type of room is assessed by the user (as weights). A case study on an existing site is presented. The view quality was arbitrarily assessed and the noise map was assessed by A-weighted equivalent sound level measurements. A general gradient-based method for finding optimal and near-optimal solutions was applied. The output of this optimization is a set of room configurations with their locations and orientations on the site returned to the user for final selection.

Keywords:
architectural optimization, subjective evaluation, functional layout, acoustic comfort, coarse grid

25.Jóźwiak-Niedźwiedzka D., Dąbrowski M., Bogusz K., Glinicki M.A., Influence of slag cement on the permeability of concrete for biological shielding structures, Energies, ISSN: 1996-1073, DOI: 10.3390/en13174582, Vol.13, No.17, pp.4582-1-16, 2020
Jóźwiak-Niedźwiedzka D., Dąbrowski M., Bogusz K., Glinicki M.A., Influence of slag cement on the permeability of concrete for biological shielding structures, Energies, ISSN: 1996-1073, DOI: 10.3390/en13174582, Vol.13, No.17, pp.4582-1-16, 2020

Abstract:
Durability of concrete designed for radiation shielding structures is an important issue in nuclear power plant safety. An investigation of the permeability of concrete containing heavyweight aggregates and water-bearing aggregates was performed with respect to gaseous and liquid media. Mix design was developed using Portland and slag cement, crushed magnetite and serpentine aggregate. The use of slag cement in concrete containing magnetite and serpentine aggregates resulted in the substantial improvement of the compressive strength in comparison with Portland cement concrete. The application of slag cement was found to reduce the chloride ingress, regardless of the special aggregate use. The coefficient of chloride migration was within the range 5 ÷ 8 × 10^−12 m^2/s and 17 ÷ 25 × 10^−12 m^2/s for slag cement concrete and Portland cement concrete, respectively. At the same time, the carbonation depth was increased twice for slag cement concrete in comparison to Portland cement concrete. However, the maximum carbonation depth after one year of exposure to 1% CO2 was only 14 mm for slag cement concrete, and 7 mm for reference concrete. The total pore volume evaluated using mercury intrusion porosimetry was influenced by the type of special aggregate used. It was shown that concrete with various contents of magnetite aggregate and slag cement achieved the smallest total pore volume. While serpentine coarse aggregate caused an increase in total pore volume in comparison to concrete with magnetite aggregate.

Keywords:
chloride permeability, carbonation, slag cement, radiation shielding concrete, microstructure, MIP, mix design, Portland cement, magnetite

26.Nosewicz S., Rojek J., Chmielewski M., Discrete element framework for determination of sintering and postsintering residual stresses of particle reinforced composites, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13184015, Vol.13, No.18, pp.4015-1- 20, 2020
Nosewicz S., Rojek J., Chmielewski M., Discrete element framework for determination of sintering and postsintering residual stresses of particle reinforced composites, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13184015, Vol.13, No.18, pp.4015-1- 20, 2020

Abstract:
In this paper, the discrete element method framework is employed to determine and analyze the stresses induced during and after the powder metallurgy process of particle-reinforced composite. Applied mechanical loading and the differences in the thermal expansion coefficients of metal/intermetallic matrix and ceramic reinforcing particles during cooling produce the complex state of stresses in and between the particles, leading to the occurrence of material defects, such as cracks, and in consequence the composite degradation. Therefore, the viscoelastic model of pressure-assisted sintering of a two-phase powder mixture is applied in order to study the stress field of particle assembly of intermetallic-ceramic composite NiAl/Al2O3. The stress evaluation is performed at two levels: macroscopic and microscopic. Macroscopic averaged stress is determined using the homogenization method using the representative volume element. Microscopic stresses are calculated both in the body of particles and in the contact interface (necks) between particles. Obtained results are in line with the cooling mechanism of the two-phase materials.

Keywords:
sintering, discrete element method, residual stress, particle-reinforced composites

27.Kukla D., Kopeć M., Kowalewski Z.L., Politis D.J., Jóźwiak S., Senderowski C., Thermal barrier stability and wear behavior of CVD deposited aluminide coatings for MAR 247 nickel superalloy, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13173863, Vol.13, No.17, pp.3863-1-11, 2020
Kukla D., Kopeć M., Kowalewski Z.L., Politis D.J., Jóźwiak S., Senderowski C., Thermal barrier stability and wear behavior of CVD deposited aluminide coatings for MAR 247 nickel superalloy, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13173863, Vol.13, No.17, pp.3863-1-11, 2020

Abstract:
In this paper, aluminide coatings of various thicknesses and microstructural uniformity obtained using chemical vapor deposition (CVD) were studied in detail. The optimized CVD process parameters of 1040 °C for 12 h in a protective hydrogen atmosphere enabled the production of high density and porosity-free aluminide coatings. These coatings were characterized by beneficial mechanical features including thermal stability, wear resistance and good adhesion strength to MAR 247 nickel superalloy substrate. The microstructure of the coating was characterized through scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis. Mechanical properties and wear resistance of aluminide coatings were examined using microhardness, scratch test and standardized wear tests, respectively. Intermetallic phases from the Ni-Al system at specific thicknesses (20-30 µm), and the chemical and phase composition were successfully evaluated at optimized CVD process parameters. The optimization of the CVD process was verified to offer high performance coating properties including improved heat, adhesion and abrasion resistance.

Keywords:
chemical vapor deposition, nickel alloys, coatings, X-ray analysis

28.Akhter M.J., Kuś W., Mrozek A., Burczyński T., Mechanical properties of monolayer MoS2 with randomly distributed defects, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13061307, Vol.13, No.6, pp.1307-1-14, 2020
Akhter M.J., Kuś W., Mrozek A., Burczyński T., Mechanical properties of monolayer MoS2 with randomly distributed defects, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13061307, Vol.13, No.6, pp.1307-1-14, 2020

Abstract:
The variation of elastic constants stiffness coefficients with respect to different percentage ratios of defects in monolayer molybdenum disulfide (MLMoS2) is reported for a particular set of atomistic nanostructural characteristics. The common method suggested is to use conventional defects such as single vacancy or di vacancy, and the recent studies use stone-walled multiple defects for highlighting the differences in the mechanical and electronic properties of 2D materials. Modeling the size influence of monolayer MoS2 by generating defects which are randomly distributed for a different percentage from 0% to 25% is considered in the paper. In this work, the geometry of the monolayer MoS2 defects modeled as randomized over the domain are taken into account. For simulation, the molecular static method is adopted and study the effect of elastic stiffness parameters of the 2D MoS2 material. Our findings reveals that the expansion of defects concentration leads to a decrease in the elastic properties, the sheer decrease in the elastic properties is found at 25%. We also study the diffusion of Molybdenum (Mo) in Sulphur (S) layers of atoms within MoS2 with Mo antisite defects. The elastic constants dwindle in the case of antisite defects too, but when compared to pure defects, the reduction was to a smaller extent in monolayer MoS2. Nevertheless, the Mo diffusion in sulfur gets to be more and more isotropic with the increase in the defect concentrations and elastic stiffness decreases with antisite defects concentration up to 25%. The distribution of antisite defects plays a vital role in modulating Mo diffusion in sulfur. These results will be helpful and give insights in the design of 2D materials.

Keywords:
mono-layer MoS2, mechanical properties, molecular statics/dynamics, defects, random distributed defects

29.Ura D.P., Rosell-Llompart J., Zaszczyńska A., Vasilyev G., Gradys A., Szewczyk P.K., Knapczyk-Korczak J., Avrahami R., Šišková A.O., Arinstein A., Sajkiewicz P., Zussman E., Stachewicz U., The role of electrical polarity in electrospinning and on the mechanical and structural properties of as-spun fibers, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13184169, Vol.13, No.18, pp.4169-1-18, 2020
Ura D.P., Rosell-Llompart J., Zaszczyńska A., Vasilyev G., Gradys A., Szewczyk P.K., Knapczyk-Korczak J., Avrahami R., Šišková A.O., Arinstein A., Sajkiewicz P., Zussman E., Stachewicz U., The role of electrical polarity in electrospinning and on the mechanical and structural properties of as-spun fibers, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13184169, Vol.13, No.18, pp.4169-1-18, 2020

Abstract:
Electric field strength and polarity in electrospinning processes and their effect on process dynamics and the physical properties of as-spun fibers is studied. Using a solution of the neutral polymer such as poly(methyl methacrylate) (PMMA) we explored the electrospun jet motion issued from a Taylor cone. We focused on the straight jet section up to the incipient stage of the bending instability and on the radius of the disk of the fibers deposited on the collecting electrode. A new correlation formula using dimensionless parameters was found, characterizing the effect of the electric field on the length of the straight jet, L˜E~E˜0.55. This correlation was found to be valid when the spinneret was either negatively or positively charged and the electrode grounded. The fiber deposition radius was found to be independent of the electric field strength and polarity. When the spinneret was negatively charged, L˜E was longer, the as-spun fibers were wider. The positively charged setup resulted in fibers with enhanced mechanical properties and higher crystallinity. This work demonstrates that often-overlooked electrical polarity and field strength parameters influence the dynamics of fiber electrospinning, which is crucial for designing polymer fiber properties and optimizing their collection.

Keywords:
fibers, electrical polarity, charges, electrospinning, PMMA, mechanical properties

30.Sciortino F., Mir S.H., Pakdel A., Oruganti A., Abe H., Witecka A., Awang Shri D.N., Rydzek G., Ariga K., Saloplastics as multiresponsive ion exchange reservoirs and catalyst supports, Journal of Materials Chemistry A, ISSN: 2050-7488, DOI: 10.1039/d0ta05901c, Vol.8, No.34, pp.17713-17724, 2020
Sciortino F., Mir S.H., Pakdel A., Oruganti A., Abe H., Witecka A., Awang Shri D.N., Rydzek G., Ariga K., Saloplastics as multiresponsive ion exchange reservoirs and catalyst supports, Journal of Materials Chemistry A, ISSN: 2050-7488, DOI: 10.1039/d0ta05901c, Vol.8, No.34, pp.17713-17724, 2020

Abstract:
Developing saloplastics composed of Compacted Polyelectrolyte Complexes (COPECs) represents a promising strategy for assembling multifunctional and processable polymer matrices in a simple manner. Here, a comprehensive investigation of the potential application of saloplastics as ion reactors for designing catalysts has been performed. First the propensity of saloplastics to exchange and concentrate ions has been elucidated through investigating the influence of Na+ to Cu2+ cation exchange within COPECs assembled from poly(methacrylic acid) (PMAA) and poly(allylamine hydrochloride) (PAH). The multi-scale responses of PMAA/PAH COPECs upon incubation with CuCl2 solutions at pH 3 and 4.5 were investigated chemically by ATR-FTIR, ICP, XPS, DSC and TGA, morphologically by SEM, and mechanically by strain-to-break measurements. Both the amplitude and the kinetics of the COPEC response were driven by the deprotonation rate of PMAA chains, enabling the formation of bridge complexes with Cu2+ and impacting the saloplastic's composition (water content and polyelectrolytes), structure (emergence of macropores) and mechanical properties. Kinetic-based tuning of the molality of copper ions trapped in PMAA/PAH COPECs was demonstrated, enabling the usage of saloplastics as reactors. This ability allowed controlling the growth of Cu(0) nanoparticles in saloplastics by thermal annealing, ultimately adjusting their catalytic activity toward carbon monoxide (CO) oxidation. This work highlights how the ionic reservoir properties of saloplastics must be accounted for when designing the applications of COPEC-based materials.

31.Strojny-Nędza A., Pietrzak K., Gili F., Chmielewski M., FGM based on copper–alumina composites for brake disc applications, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-020-00079-1, Vol.20, No.3, pp.83-1-13, 2020
Strojny-Nędza A., Pietrzak K., Gili F., Chmielewski M., FGM based on copper–alumina composites for brake disc applications, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-020-00079-1, Vol.20, No.3, pp.83-1-13, 2020

Abstract:
Copper-alumina composites of the interpenetrating networks type are interesting materials for many applications because of their properties. On the base of preliminary investigations and practical works, in order to obtain a material with high resistance to friction wear as well as good dissipation of heat generated during work, it was decided that a developed material would be prepared on the base of the Cu-Al2O3 composite, with a graded composition. In this paper, we present the developed method of manufacturing dense copper–alumina FGMs, using ceramic preform with a graded porosity infiltrated with molten copper. The article also presents the full characterization of the obtained materials and mainly the impact of microstructure on the useful properties. The produced gradient material of a Cu-Al2O3 brake disk underwent tribological tests under conditions resembling real conditions. These disks also went through a series of abrasive wear trials at different operation stages. In comparison with the reference material (i.e., grey cast iron), the obtained gradient materials are characterized by a lower degree of wear when retaining a similar coefficient of friction value due to the ceramic phase addition. Additionally, it was found that using the copper-based gradient material guarantees faster heat dissipation from the contact area.

Keywords:
composites, interpenetrating network materials, functionally gradient materials, brake disc

32.Zeller-Plumhoff B., Robisch A.L., Pelliccia D., Longo E., Słomińska H., Hermann A., Krenkel M., Storm M., Estrin Y., Willumeit-Römer R., Salditt T., Orlov D., Nanotomographic evaluation of precipitate structure evolution in a Mg–Zn–Zr alloy during plastic deformation, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-020-72964-x, Vol.10, pp.16101-1-9, 2020
Zeller-Plumhoff B., Robisch A.L., Pelliccia D., Longo E., Słomińska H., Hermann A., Krenkel M., Storm M., Estrin Y., Willumeit-Römer R., Salditt T., Orlov D., Nanotomographic evaluation of precipitate structure evolution in a Mg–Zn–Zr alloy during plastic deformation, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-020-72964-x, Vol.10, pp.16101-1-9, 2020

Abstract:
Magnesium and its alloys attract increasingly wide attention in various fields, ranging from transport to medical solutions, due to their outstanding structural and degradation properties. These properties can be tailored through alloying and thermo-mechanical processing, which is often complex and multi-step, thus requiring in-depth analysis. In this work, we demonstrate the capability of synchrotron-based nanotomographic X-ray imaging methods, namely holotomography and transmission X-ray microscopy, for the quantitative 3D analysis of the evolution of intermetallic precipitate (particle) morphology and distribution in magnesium alloy Mg–5.78Zn-0.44Zr subjected to a complex multi-step processing. A rich history of variation of the intermetallic particle structure in the processed alloy provided a testbed for challenging the analytical capabilities of the imaging modalities studied. The main features of the evolving precipitate structure revealed earlier by traditional light and electron microscopy methods were confirmed by the 3D techniques of synchrotron-based X-ray imaging. We further demonstrated that synchrotron-based X-ray imaging enabled uncovering finer details of the variation of particle morphology and number density at various stages of processing—above and beyond the information provided by visible light and electron microscopy.

33.Jaskulski R., Jóźwiak-Niedźwiedzka D., Yakymechko Y., Calcined Clay as Supplementary Cementitious Material, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13214734, Vol.13, No.21, pp.4734-1-36, 2020
Jaskulski R., Jóźwiak-Niedźwiedzka D., Yakymechko Y., Calcined Clay as Supplementary Cementitious Material, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13214734, Vol.13, No.21, pp.4734-1-36, 2020

Abstract:
Calcined clays are the only potential materials available in large quantities to meet the requirements of eco-efficient cement-based materials by reducing the clinker content in blended cements or reducing the cement content in concrete. More than 200 recent research papers on the idea of replacing Portland cement with large amounts of calcined clay are presented and discussed in detail. First, the fundamental information about the properties and structure of clay minerals is described. Then, the process of activation and hydration of clays is discussed, including the methods of pozzolanic activity assessment. Additionally, various testing methods of clays from different worldwide deposits are presented. The application of calcined clay in cement and concrete technology is then introduced. A separate chapter is devoted to lime calcined clay cement. Then an influence of calcined clay on durability of concrete is summarized. Finally, conclusions are formulated.

Keywords:
calcined clay, binder, supplementary cementitious materials, cement-based materials

34.Rutecka A., Kursa M., Pietrzak K., Kowalczyk-Gajewska K., Makowska K., Wyszkowski M., Damage evolution in AA2124/SiC metal matrix composites under tension with consecutive unloadings, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-020-00134-x, Vol.20, No.4, pp.135-1-18, 2020
Rutecka A., Kursa M., Pietrzak K., Kowalczyk-Gajewska K., Makowska K., Wyszkowski M., Damage evolution in AA2124/SiC metal matrix composites under tension with consecutive unloadings, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-020-00134-x, Vol.20, No.4, pp.135-1-18, 2020

Abstract:
Nonlinear properties of metal matrix composites (MMCs) are studied. The research combines results of loading-unloading tensile tests, microstructural observations and numerical predictions by means of micromechanical mean-field models. AA2124/SiC metal matrix composites with SiC particles, produced by the Aerospace Metal Composites Ltd. (AMC) are investigated. The aluminum matrix is reinforced with 17% and 25% of SiC particles. The best conditions to evaluate the current elastic stiffness modulus have been assessed. Tensile tests were carried out with consecutive unloading loops to obtain actual tensile modulus and study degradation of elastic properties of the composites. The microstructure examination by scanning electron microscopy (SEM) showed a variety of phenomena occurring during composite deformation and possible sources of elastic stiffness reduction and damage evolution have been indicated. Two micromechanical approaches, the incremental Mori–Tanaka (MT) and self-consistent (SC) schemes, are applied to estimate effective properties of the composites. The standard formulations are extended to take into account elasto-plasticity and damage development in the metal phase. The method of direct linearization performed for the tangent or secant stiffness moduli is formulated. Predictions of both approaches are compared with experimental results of tensile tests in the elastic–plastic regime. The question is addressed how to perform the micromechanical modelling if the actual stress–strain curve of metal matrix is unknown.

Keywords:
metal matrix composites, tension with unloadings, damage, microstructure, non-linear effective properties

35.Lee B.Y., Chu C.T., Krajewski M., Michalska M., Lin J.Y., Temperature-controlled synthesis of spinel lithium nickel manganese oxide cathode materials for lithium-ion batteries, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2020.05.124, Vol.46, No.13, pp.20856-20864, 2020
Lee B.Y., Chu C.T., Krajewski M., Michalska M., Lin J.Y., Temperature-controlled synthesis of spinel lithium nickel manganese oxide cathode materials for lithium-ion batteries, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2020.05.124, Vol.46, No.13, pp.20856-20864, 2020

Abstract:
In this work, we successfully synthesized series of LiNi0.5Mn1.5O4 (LNMO) cathode materials with spinel structure by using a facile sol-gel method and then calcined at various temperature ranging from 600 to 1000 °C. The application of different calcination temperatures significantly influenced the surface morphology, stoichiometry and crystalline nature of the as-synthesized LNMO material. According to the results of physical characterizations, the LNMO materials calcined at various temperatures mainly revealed the stoichiometric disordered Fd-3m structure with a small amount of well-ordered P4332 phase. The structural analysis also exhibited that the control of the calcination temperature contributed to the higher crystalline nature. Moreover, the morphological investigations indicated that the increasing calcination temperatures caused the formation of large micron-sized LNMO material. In turn, the electrochemical evaluations revealed the impact of the calcination temperatures on enhancing the electrochemical performances of the LNMO electrode materials up to 900 °C. The LNMO electrode calcined at 900 °C exhibited an impressive initial discharge specific capacity of ca. 142 mAh g^−1 between 3.5 and 4.9 V vs. Li/Li+, and remarkably improved capacity retention of 97% over 50 cycles. Those excellent electrochemical properties were associated with the presence of the dominant Fd-3m phase over the P4332 phase. Additionally, the results of the corrosion and dissolution tests which were performed for all calcined LNMO materials in order to estimate the amount of manganese and nickel ions leached from them, proved that the micro-sized LNMO calcined at 900 °C was the most stable.

Keywords:
spinel LiNi0.5Mn1.5O4, sol-gel synthesis, calcination temperature, cathode material, lithium-ion batteries

36.Hou J., Li Z., Zhang Q., Jankowski Ł., Zhang H., Local mass addition and data fusion for structural damage identification using approximate models, International Journal of Structural Stability and Dynamics, ISSN: 1793-6764, DOI: 10.1142/S0219455420501242, pp.1-24, 2020
Hou J., Li Z., Zhang Q., Jankowski Ł., Zhang H., Local mass addition and data fusion for structural damage identification using approximate models, International Journal of Structural Stability and Dynamics, ISSN: 1793-6764, DOI: 10.1142/S0219455420501242, pp.1-24, 2020

Abstract:
In practical civil engineering, structural damage identification is difficult to implement due to the shortage of measured modal information and the influence of noise. Furthermore, typical damage identification methods generally rely on a precise Finite Element (FE) model of the monitored structure. Pointwise mass alterations of the structure can effectively improve the quantity and sensitivity of measured data, while the data fusion methods can adequately utilize various kinds of data and identification results. This paper proposes a damage identification method that requires only approximate FE models and combines the advantages of pointwise mass additions and data fusion. First, an additional mass is placed at different positions throughout the structure to collect the dynamic response and obtain the corresponding modal information. The resulting relation between natural frequencies and the position of the added mass is sensitive to local damage, and it is thus utilized to form a new objective function based on the modal assurance criterion (MAC) and l1-based sparsity promotion. The proposed objective function is mostly insensitive to global structural parameters, but remains sensitive to local damage. Several approximate FE models are then established and separately used to identify the damage of the structure, and then the Dempster-Shafer method of data fusion is applied to fuse the results from all the approximate models. Finally, fractional data fusion is proposed to combine the results according to the parametric probability distribution of the approximate FE models, which allows the natural weight of each approximate model to be determined for the fusion process. Such an approach circumvents the need for a precise FE model, which is usually not easy to obtain in real application, and thus enhances the practical applicability of the proposed method, while maintaining the damage identification accuracy. The proposed approach is verified numerically and experimentally. Numerical simulations of a simply supported beam and a long-span bridge confirm that it can be used for damage identification, including a single damage and multiple damages, with a high accuracy. Finally, an experiment of a cantilever beam is successfully performed.

Keywords:
structural health monitoring (SHM), damage identification, adding mass, data fusion, objective function, modal assurance criterion (MAC)

37.Luo L., Akinoglu E.M., Wu W., Dodge T., Wang X., Zhou G., Naughton M.J., Kempa K., Giersig M., Nano-bridged nanosphere lithography, NANOTECHNOLOGY, ISSN: 0957-4484, DOI: 10.1088/1361-6528/ab7c4c, Vol.31, pp.245302-1-6, 2020
Luo L., Akinoglu E.M., Wu W., Dodge T., Wang X., Zhou G., Naughton M.J., Kempa K., Giersig M., Nano-bridged nanosphere lithography, NANOTECHNOLOGY, ISSN: 0957-4484, DOI: 10.1088/1361-6528/ab7c4c, Vol.31, pp.245302-1-6, 2020

Abstract:
We develop nano-bridged nanosphere lithography (NB-NSL), a modification to the widely used conventional nanosphere lithography (NSL). Nano-bridges between polystyrene (PS) spheres of a pristine NSL template are controllably formed in a two-step process: (i) spin-coating of a dilute styrene solution on top of the template, followed by (ii) oxygen plasma etching of the template. We show that the nanobridge dimensions can be precisely tuned by controlling the pre-processing conditions and the plasma etching time. The resulting lithography templates feature control over the shape and size of the apertures, which determine the morphology of the final nano-island arrays after material deposition and template removal. The unique advantage of NB-NSL is that PS particle templates based on a single PS particle diameter can be utilized for the fabrication of a variation of nano-island shapes and sizes, whereas conventional NSL yields only bowtie-shaped nano-islands, with their size being predetermined by the PS particle diameter of the template.

Keywords:
nanofabrication, nanosphere lithography, colloid lithography

38.Kołbuk D., Jeznach O., Wrzecionek M., Gadomska-Gajadhur A., Poly(glycerol succinate) as an eco-friendly component of PLLA and PLCL fibres towards medical applications, Polymers, ISSN: 2073-4360, DOI: 10.3390/polym12081731, Vol.12, No.8, pp.1731-1-17, 2020
Kołbuk D., Jeznach O., Wrzecionek M., Gadomska-Gajadhur A., Poly(glycerol succinate) as an eco-friendly component of PLLA and PLCL fibres towards medical applications, Polymers, ISSN: 2073-4360, DOI: 10.3390/polym12081731, Vol.12, No.8, pp.1731-1-17, 2020

Abstract:
This study was conducted as a first step in obtaining eco-friendly fibres for medical applications using a synthesised oligomer poly(glycerol succinate) (PGSu) as an additive for synthetic poly(L-lactic acid) (PLLA) and poly (L-lactide-co-caprolactone) (PLCL). The effects of the oligomer on the structure formation, morphology, crystallisation behaviour, and mechanical properties of electrospun bicomponent fibres were investigated. Nonwovens were investigated by means of scanning electron microscopy (SEM), wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), and mechanical testing. The molecular structure of PLLA fibres is influenced by the presence of PGSu mainly acting as an enhancer of molecular orientation. In the case of semicrystalline PLCL, chain mobility was enhanced by the presence of PGSu molecules, and the crystallinity of bicomponent fibres increased in relation to that of pure PLCL. The mechanical properties of bicomponent fibres were influenced by the level of PGSu present and the extent of crystal formation of the main component. An in vitro study conducted using L929 cells confirmed the biocompatible character of all bicomponent fibres.

Keywords:
poly(glycerol succinate), plasticiser, eco-friendly polymer, electrospinning, hyperbranched polyester

39.Gupta A., Jain A., Tripathi S., Structural and electrochemical studies of bromide derived ionic liquid-based gel polymer electrolyte for energy storage application, Journal of Energy Storage, ISSN: 2352-152X, DOI: 10.1016/j.est.2020.101723, Vol.32, pp.101723-1-7, 2020
Gupta A., Jain A., Tripathi S., Structural and electrochemical studies of bromide derived ionic liquid-based gel polymer electrolyte for energy storage application, Journal of Energy Storage, ISSN: 2352-152X, DOI: 10.1016/j.est.2020.101723, Vol.32, pp.101723-1-7, 2020

Abstract:
In the present studies, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), ionic liquid {1-Ethyl-3-methylimidazolium bromide} (EMIM)(Br), and magnesium perchlorate Mg(ClO4)2 as salt were used to synthesize free standing electrolyte films by using solution cast technique. The prepared electrolyte films were investigated by using various structural and electrochemical techniques like scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) as well as ionic and temperature dependence studies. It has been observed that addition of ionic liquid significantly increases the properties like ionic conductivity, thermal stability, transparency etc. The maximum room temperature ionic conductivity for the optimized system was found to be of the order of 2.05 × 10^−2 S cm^−1 which is suitable for device fabrication point of view. The optimized electrolyte films are suitable for supercapacitor application.

Keywords:
gel polymer electrolytes, ionic liquid, solution cast technique, supercapacitors

40.Magliulo M., Lengiewicz J., Zilian A., Beex L.A.A., Beam-inside-beam contact: mechanical simulations of slender medical instruments inside the human body, Computer Methods and Programs in Biomedicine, ISSN: 0169-2607, DOI: 10.1016/j.cmpb.2020.105527, Vol.196, pp.105527-1-14, 2020
Magliulo M., Lengiewicz J., Zilian A., Beex L.A.A., Beam-inside-beam contact: mechanical simulations of slender medical instruments inside the human body, Computer Methods and Programs in Biomedicine, ISSN: 0169-2607, DOI: 10.1016/j.cmpb.2020.105527, Vol.196, pp.105527-1-14, 2020

Abstract:
This contribution presents a rapid computational framework to mechanically simulate the insertion of a slender medical instrument in a tubular structure such as an artery, the cochlea or another slender instrument.

Keywords:
surgical simulation, contact mechanics, beam-inside-beam, artery, cochlea

41.Pnevmatikos N., Konstandakopoulou F., Błachowski B., Papavasileiou G., Broukos P., Multifractal analysis and wavelet leaders for structural damage detection of structures subjected to earthquake excitation, Soil Dynamics and Earthquake Engineering, ISSN: 0267-7261, DOI: 10.1016/j.soildyn.2020.106328, Vol.139, pp.106328-1-4, 2020
Pnevmatikos N., Konstandakopoulou F., Błachowski B., Papavasileiou G., Broukos P., Multifractal analysis and wavelet leaders for structural damage detection of structures subjected to earthquake excitation, Soil Dynamics and Earthquake Engineering, ISSN: 0267-7261, DOI: 10.1016/j.soildyn.2020.106328, Vol.139, pp.106328-1-4, 2020

Abstract:
This work is an effort to join, for the first-time, multifractal analysis and damage detection in civil structures subjected to strong ground seismic motions. Specifically, based on the singularity spectrum quantitative and qualitative criteria are proposed. The qualitative criteria are based on the concave of singularity spectrum of damage and undamaged structure. The proposed quantitative criterion is based on calculation of damage index taken the parameters of singularity spectrum. In order to achieve the above goal, a robust signal processing method, which is known as multifractal wavelet leader (MFWL) is used. The multifractal analysis is a tool to calculate fractal properties as well as scaling behavior of the structural response excited by an earthquake. The singularity spectrum is obtained from the Legendre-transformation to Holder exponents. In this paper, a parameter which is based on the shape of singularity spectrum and can identify the damage in the structure is proposed. The proposed method is an output-only approach for damage detection. Considering that the dynamic behavior of an inelastic system subjected to strong ground motion appears to be a non-stationary process, the above procedure of multifractal wavelet leader is suitable to retrieve the simulation response data. The findings from the analysis show that the MFWL is an appropriate scheme for structural damage detection.

Keywords:
multifractal wavelet leader, damage detection, singularity spectrum, earthquake engineering, structural safety

42.Meissner M., Wiśniewski K., Investigation of damping effects on low-frequency steady-state acoustical behaviour of coupled spaces, Royal Society Open Science, ISSN: 2054-5703, DOI: 10.1098/rsos.200514, Vol.7, No.8, pp.200514-1-14, 2020
Meissner M., Wiśniewski K., Investigation of damping effects on low-frequency steady-state acoustical behaviour of coupled spaces, Royal Society Open Science, ISSN: 2054-5703, DOI: 10.1098/rsos.200514, Vol.7, No.8, pp.200514-1-14, 2020

Abstract:
In the low-frequency range, the acoustical behaviour of enclosed spaces is strongly influenced by excited acoustic modes resulting in a spatial irregularity of a steady-state sound field. In the paper, this problem has been examined theoretically and numerically for a system of coupled spaces with complex-valued conditions on boundary surfaces. Using a modal expansion method, an analytic formula for the Green's function was derived allowing to predict the interior sound field for a pure-tone excitation. To quantify the spatial irregularity of steady-state sound field, the parameter referred to as the mean spatial deviation was introduced. A numerical simulation was carried out for the system consisting of two coupled rectangular subspaces. Eigenfunctions and eigenfrequencies for this system were determined using the high-accuracy eigenvalue solver. As was evidenced by computational data, for small sound damping on absorptive walls the mean spatial deviation peaks at frequencies corresponding to eigenfrequencies of strongly localized modes. However, if the sound damping is much higher, the main cause of spatial irregularity of the interior sound field is the appearance of sharp valleys in a spatial distribution of a sound pressure level.

Keywords:
interior acoustics, coupled spaces, steady-state sound field, modal expansion method, sound damping, Green's function

43.Szymczak T., Kowalewski Z.L., Strength tests of polymer-glass composite to evaluate its operational suitability for ballistic shield plates, EKSPLOATACJA I NIEZAWODNOŚĆ - MAINTENANCE AND RELIABILITY, ISSN: 1507-2711, DOI: 10.17531/ein.2020.4.2, Vol.22, No.4, pp.592-600, 2020
Szymczak T., Kowalewski Z.L., Strength tests of polymer-glass composite to evaluate its operational suitability for ballistic shield plates, EKSPLOATACJA I NIEZAWODNOŚĆ - MAINTENANCE AND RELIABILITY, ISSN: 1507-2711, DOI: 10.17531/ein.2020.4.2, Vol.22, No.4, pp.592-600, 2020

Abstract:
The paper concerns the study of polymer-glass composite under tensile loading in order to determine changes in the tensile characteristics. Mechanical properties and features of damage zones important for operation and assessment of the technical conditions of the components made of this material are considered. Selected details of the experimental technique used are presented. The tensile characteristics of the polymer-glass composite are given. They were determined using specimens taken from various directions, with the main focus on the Young's modulus, elastic limit, yield point and ultimate tensile strength. An influence of the number of reinforcement layers, percentage content of the glass fibres as well as the resin quantity, on the mechanical parameters, are discussed.

Keywords:
composite, reinforcement, anisotropy, tensile curve, mechanical properties, structure, degradation, cracking, delamination

44.Kochańczyk M., Grabowski F., Lipniacki T., Super-spreading events initiated the exponential growth phase of COVID-19 with R-0 higher than initially estimated, Royal Society Open Science, ISSN: 2054-5703, DOI: 10.1098/rsos.200786, Vol.7, No.9, pp.200786-1-9, 2020
Kochańczyk M., Grabowski F., Lipniacki T., Super-spreading events initiated the exponential growth phase of COVID-19 with R-0 higher than initially estimated, Royal Society Open Science, ISSN: 2054-5703, DOI: 10.1098/rsos.200786, Vol.7, No.9, pp.200786-1-9, 2020

Abstract:
The basic reproduction number R0 of the coronavirus disease 2019 has been estimated to range between 2 and 4. Here, we used an SEIR model that properly accounts for the distribution of the latent period and, based on empirical estimates of the doubling time in the near-exponential phases of epidemic progression in China, Italy, Spain, France, UK, Germany, Switzerland and New York State, we estimated that R0 lies in the range 4.7-11.4. We explained this discrepancy by performing stochastic simulations of model dynamics in a population with a small proportion of super-spreaders. The simulations revealed two-phase dynamics, in which an initial phase of relatively slow epidemic progression diverts to a faster phase upon appearance of infectious super-spreaders. Early estimates obtained for this initial phase may suggest lower R0.

Keywords:
COVID-19, reproduction number

45.Ozen M., Lipniacki T., Levchenko A., Emamian E.S., Abdi A., Modeling and measurement of signaling outcomes affecting decision making in noisy intracellular networks using machine learning methods, Integrative Biology, ISSN: 1757-9708, DOI: 10.1093/intbio/zyaa009, Vol.12, No.5, pp.122-138, 2020
Ozen M., Lipniacki T., Levchenko A., Emamian E.S., Abdi A., Modeling and measurement of signaling outcomes affecting decision making in noisy intracellular networks using machine learning methods, Integrative Biology, ISSN: 1757-9708, DOI: 10.1093/intbio/zyaa009, Vol.12, No.5, pp.122-138, 2020

Abstract:
Characterization of decision-making in cells in response to received signals is of importance for understanding how cell fate is determined. The problem becomes multi-faceted and complex when we consider cellular heterogeneity and dynamics of biochemical processes. In this paper, we present a unified set of decision-theoretic, machine learning and statistical signal processing methods and metrics to model the precision of signaling decisions, in the presence of uncertainty, using single cell data. First, we introduce erroneous decisions that may result from signaling processes and identify false alarms and miss events associated with such decisions. Then, we present an optimal decision strategy which minimizes the total decision error probability. Additionally, we demonstrate how graphing receiver operating characteristic curves conveniently reveals the trade-off between false alarm and miss probabilities associated with different cell responses. Furthermore, we extend the introduced framework to incorporate the dynamics of biochemical processes and reactions in a cell, using multi-time point measurements and multi-dimensional outcome analysis and decision-making algorithms. The introduced multivariate signaling outcome modeling framework can be used to analyze several molecular species measured at the same or different time instants. We also show how the developed binary outcome analysis and decision-making approach can be extended to more than two possible outcomes. As an example and to show how the introduced methods can be used in practice, we apply them to single cell data of PTEN, an important intracellular regulatory molecule in a p53 system, in wild-type and abnormal cells. The unified signaling outcome modeling framework presented here can be applied to various organisms ranging from viruses, bacteria, yeast and lower metazoans to more complex organisms such as mammalian cells. Ultimately, this signaling outcome modeling approach can be utilized to better understand the transition from physiological to pathological conditions such as inflammation, various cancers and autoimmune diseases.

Keywords:
Cell decision making, noise, decision theory, machine learning, signaling errors, p53 system

46.Starzyński G., Buczkowski R., Zyliński B., Deformation-induced roughening by contact compression in the presence of oils with different viscosity: experiment and numerical simulation, TRIBOLOGY LETTERS, ISSN: 1023-8883, DOI: 10.1007/s11249-020-01353-2, Vol.68, No.4, pp.117-1-14, 2020
Starzyński G., Buczkowski R., Zyliński B., Deformation-induced roughening by contact compression in the presence of oils with different viscosity: experiment and numerical simulation, TRIBOLOGY LETTERS, ISSN: 1023-8883, DOI: 10.1007/s11249-020-01353-2, Vol.68, No.4, pp.117-1-14, 2020

Abstract:
The aim of the work is to show both the similarities and differences in the formation of deformation-induced roughness in contact compression in the presence of oil and the problem of free surface roughing during uniaxial stretching in a plastic area. The relationships between changes in the roughness are caused by the deformation of the sample and the viscosity of oil at the contact area. It has been shown that normal contact loading with the presence of oil initially leads to an increase in surface roughness, then to its smoothening. The results of the experimental research have been compared with numerical simulation made using FSI (Fluid Structure Interaction) and ABAQUS systems. Using finite element calculations, it was possible to explain the phenomenon of roughness formation on the surface of a smooth steel sample. The changes in the structure of the smooth surface resulting from compression in the presence of oil are caused by the rotation and deformation of surface grains. The roughness of this structure is dependent on the viscosity of oil: the more viscous the liquid is, the rougher texture is formed.

Keywords:
deformation-induced roughening, viscosity, finite element method

47.Orłowska A., Gałęzia A., Świercz A., Jankowski Ł., Mitigation of vibrations in sandwich-type structures by a controllable constrained layer, JOURNAL OF VIBRATION AND CONTROL, ISSN: 1077-5463, DOI: 10.1177/1077546320946130, pp.1-11, 2020
Orłowska A., Gałęzia A., Świercz A., Jankowski Ł., Mitigation of vibrations in sandwich-type structures by a controllable constrained layer, JOURNAL OF VIBRATION AND CONTROL, ISSN: 1077-5463, DOI: 10.1177/1077546320946130, pp.1-11, 2020

Abstract:
This study presents and tests a method for semi-active control of vibrations in sandwich-type beam structures. This method adapts a strategy called prestress accumulation release. The prestress accumulation release strategy is based on structural reconfiguration: it uses short time, impulsive and localised changes of actuator properties (such as stiffness or damping), which are applied to a part of the system in the moments, when its strain energy attains a local maximum. The method has been earlier applied as a global control scheme to mitigate the fundamental vibration mode of a cantilever beam (by stiffness control) and in the task of mitigating the first four modes of a frame structure (by damping control). This study proposes a prestress accumulation release strategy and tests its effectiveness for the case of a three-layered sandwich structure, with the internal layer fabricated from a material with dissipative characteristic locally controllable through the material damping coefficient. In contrast to the earlier research, the control is applied thus at the level of material characteristics instead of a discrete set of dedicated actuators. Based on the finite element method, a numerical experiment involving a passively damped, as well as prestress accumulation release-controlled, three-layered cantilever beam excited by initial displacements was performed. The effectiveness of the approach was studied for a broad range of internal layer damping parameters. The presented results revealed a high potential of the prestress accumulation release strategy in semi-active damping of vibrations of sandwich-type structures.

Keywords:
vibration control, sandwich structure, semi-active control, decentralised control, smart structures, constrained layer method

48.Byra M., Hentzen E., Du J., Andre M., Chang E.Y., Shah S., Assessing the performance of morphologic and echogenic features in median nerve ultrasound for carpal tunnel syndrome diagnosis, Journal of Ultrasound in Medicine, ISSN: 0278-4297, DOI: 10.1002/jum.15201, Vol.39, No.6, pp.1165-1174, 2020
Byra M., Hentzen E., Du J., Andre M., Chang E.Y., Shah S., Assessing the performance of morphologic and echogenic features in median nerve ultrasound for carpal tunnel syndrome diagnosis, Journal of Ultrasound in Medicine, ISSN: 0278-4297, DOI: 10.1002/jum.15201, Vol.39, No.6, pp.1165-1174, 2020

Abstract:
Objectives: To assess the feasibility of using ultrasound (US) image features related to the median nerve echogenicity and shape for carpal tunnel syndrome (CTS) diagnosis. Methods: In 31 participants (21 healthy participants and 10 patients with CTS), US images were collected with a 30-MHz transducer from median nerves at the wrist crease in 2 configurations: a neutral position and with wrist extension. Various morphologic features, including the cross-sectional area (CSA), were calculated to assess the nerve shape. Carpal tunnel syndrome commonly results in loss of visualization of the nerve fascicular pattern on US images. To assess this phenomenon, we developed a nerve-tissue contrast index (NTI) method. The NTI is a ratio of average brightness levels of surrounding tissue and the median nerve, both calculated on the basis of a US image. The area under the curve (AUC) from a receiver operating characteristic curve analysis and t test were used to assess the usefulness of the features for differentiation of patients with CTS from control participants. Results: We obtained significant differences in the CSA and NTI parameters between the patients with CTS and control participants (P < .01), with the corresponding highest AUC values equal to 0.885 and 0.938, respectively. For the remaining investigated morphologic features, the AUC values were less than 0.685, and the differences in means between the patients and control participants were not statistically significant (P > .10). The wrist configuration had no impact on differences in average parameter values (P > .09). Conclusions: Patients with CTS can be differentiated from healthy individuals on the basis of the median nerve CSA and echogenicity. Carpal tunnel syndrome is not manifested in a change of the median nerve shape that could be related to circularity or contour variability.

Keywords:
carpal tunnel syndrome, cross-sectional area, echogenicity, median nerve, morphologic features, ultrasound

49.Caporale R., Darban H., Luciano R., Exact closed-form solutions for nonlocal beams with loading discontinuities, MECHANICS OF ADVANCED MATERIALS AND STRUCTURES, ISSN: 1537-6494, DOI: 10.1080/15376494.2020.1787565, pp.1-11, 2020
Caporale R., Darban H., Luciano R., Exact closed-form solutions for nonlocal beams with loading discontinuities, MECHANICS OF ADVANCED MATERIALS AND STRUCTURES, ISSN: 1537-6494, DOI: 10.1080/15376494.2020.1787565, pp.1-11, 2020

Abstract:
A novel mathematical formulation is presented for the applications of the stress-driven nonlocal theory of elasticity to engineering nano-scale problems requiring longitudinal discretization. Specifically, a differential formulation accompanied with novel constitutive continuity conditions is provided for determining exact closed-form solutions of nonlocal Euler-Bernoulli beams with loading discontinuities, i.e. points of discontinuity for external loads and internal forces. Constitutive continuity conditions have to be satisfied in interior points where a loading discontinuity occurs and contain integral convolutions of the stress over suitable parts of the nonlocal beam. Several results show the effectiveness of the proposed method.

Keywords:
closed-form solutions, discretization, Euler-Bernoulli beams, nanobeams

50.Luciano R., Caporale A., Darban H., Bartolomeo C., Variational approaches for bending and buckling of non-local stress-driven Timoshenko nano-beams for smart materials, Mechanics Research Communications, ISSN: 0093-6413, DOI: 10.1016/j.mechrescom.2019.103470, Vol.103, pp.103470-1-7, 2020
Luciano R., Caporale A., Darban H., Bartolomeo C., Variational approaches for bending and buckling of non-local stress-driven Timoshenko nano-beams for smart materials, Mechanics Research Communications, ISSN: 0093-6413, DOI: 10.1016/j.mechrescom.2019.103470, Vol.103, pp.103470-1-7, 2020

Abstract:
In this work, variational formulations are proposed for solving numerically the problem of bending and buckling of Timoshenko nano-beams. The present work belongs to research branch in which the non-local theory of elasticity has been used for analysis of beam-like elements in smart materials, micro-electro-mechanical (MEMS) or nano-electro-mechanical systems (NEMS). In fact, the local beam theory is not adequate to describe the behavior of beam-like elements of smart materials at the nano-scale, so that different non-local models have been proposed in last decades for nano-beams. The nano-beam model considered in this work is a convex combination (mixture) of local and non-local phases. In the non-local phase, the kinematic entities in a point of the nano-beam are expressed as integral convolutions between internal forces and an exponential kernel. The aim is to construct a functional whose stationary condition provides the solution of the problem. Two different functionals are defined: one for the pure non-local model, where the local fraction of the mixture is absent, and the other for the mixture with both local and non-local phases. The Euler equations of the two functionals are derived; then, attention focuses on the mixture model. The functional of the mixture depends on unknown Lagrange multipliers and the Euler equations of the functional provide not only the governing equations of the problem but also the relationships between these Lagrange multipliers and the other variables on which the functional depends. In fact, approximations of the variables of the functional can not be chosen arbitrarily in numerical analyzes but have to satisfy suitable conditions. The Euler equations involving the Lagrange multipliers are essential in the numerical analyzes and suggest the correct approximations that have to be adopted for Lagrange multipliers and the other unknown variables of the functional. The proposed method is verified by comparing numerical solutions with exact solutions in bending problem. Finally, the method is used to determine the buckling load of Timoshenko nano-beams with mixture of phases.

Keywords:
non-local elasticity, variational methods, Timoshenko beam, buckling load, smart materials

51.Luciano R., Darban H., Bartolomeo C., Fabbrocino F., Scorza D., Free flexural vibrations of nanobeams with non-classical boundary conditions using stress-driven nonlocal model, Mechanics Research Communications, ISSN: 0093-6413, DOI: 10.1016/j.mechrescom.2020.103536, Vol.107, pp.103536-1-5, 2020
Luciano R., Darban H., Bartolomeo C., Fabbrocino F., Scorza D., Free flexural vibrations of nanobeams with non-classical boundary conditions using stress-driven nonlocal model, Mechanics Research Communications, ISSN: 0093-6413, DOI: 10.1016/j.mechrescom.2020.103536, Vol.107, pp.103536-1-5, 2020

Abstract:
Free flexural vibrations of nanobeams with non-rigid edge supports are studied by means of the stress-driven nonlocal elasticity model and Euler-Bernoulli kinematics. The elastic deformations of the supports are modelled by transversal and flexural springs, so that, in the limit conditions when the springs stiffnesses tend to zero or infinity, the classical free, pinned, and clamped boundary conditions may be recovered. An analytical procedure is used to derive the closed form solution of the spatial differential equation. The problem of finding the natural frequencies is then reduced to find the roots of the determinant of a matrix, whose elements are explicitly given. The proposed technique, then, avoids the numerical instabilities usually arising when the numerical techniques are used to obtain the solution. The effects of both non-rigid supports elastic deformations and nonlocal parameter on the natural frequencies are studied also for higher vibrations modes. The comparison between the solutions of the proposed model and those available in the literature shows an excellent agreement, and new insightful results and discussions are presented.

Keywords:
elastically constrained beam, nanostructures, natural frequency, size effects, well-posed nonlocal formulation

52.Darban H., Fabbrocino F., Feo L., Luciano R., Size-dependent buckling analysis of nanobeams resting on two-parameter elastic foundation through stress-driven nonlocal elasticity model, MECHANICS OF ADVANCED MATERIALS AND STRUCTURES, ISSN: 1537-6494, DOI: 10.1080/15376494.2020.1739357, pp.1-9, 2020
Darban H., Fabbrocino F., Feo L., Luciano R., Size-dependent buckling analysis of nanobeams resting on two-parameter elastic foundation through stress-driven nonlocal elasticity model, MECHANICS OF ADVANCED MATERIALS AND STRUCTURES, ISSN: 1537-6494, DOI: 10.1080/15376494.2020.1739357, pp.1-9, 2020

Abstract:
The instability of nanobeams rested on two-parameter elastic foundations is studied through the Bernoulli-Euler beam theory and the stress-driven nonlocal elasticity model. The size-dependency is incorporated into the formulation by defining the strain at each point as an integral convolution in terms of the stresses in all the points and a kernel. The nonlocal elasticity problem in a bounded domain is well-posed and inconsistencies within the Eringen nonlocal theory are overcome. Excellent agreement is found with the results in the literature, and new insightful results are presented for the buckling loads of nanobeams rested on the Winkler and Pasternak foundations.

Keywords:
buckling, closed form solution, nanobeam, nonlocal elasticity, Pasternak foundation, stress-driven

53.Kruk A., Gadomska-Gajadhur A., Dulnik J., Ruśkowski P., The influence of the molecular weight of polymer on the morphology, functional properties and L929 fibroblasts growth on polylactide membranes for tissue engineering, International Journal of Polymeric Materials and Polymeric Biomaterials, ISSN: 0091-4037, DOI: 10.1080/00914037.2020.1798440, pp.1-13, 2020
Kruk A., Gadomska-Gajadhur A., Dulnik J., Ruśkowski P., The influence of the molecular weight of polymer on the morphology, functional properties and L929 fibroblasts growth on polylactide membranes for tissue engineering, International Journal of Polymeric Materials and Polymeric Biomaterials, ISSN: 0091-4037, DOI: 10.1080/00914037.2020.1798440, pp.1-13, 2020

Abstract:
The main goal of tissue engineering (TE) is supporting the regeneration of damaged tissues that are difficult to regenerate. The experimental results of the preparation of semi-permeable membranes for cell cultures are presented. The effect of the PLA molecular weight and addition of pore precursors on the morphology of the membranes was studied. The pore precursor of choice was polyvinylpyrrolidone (PVP). It was found that semi-permeable membranes for application in tissue engineering can be prepared with polylactides of molecular weight more significant than 37,000 g/mol. Moreover, it was observed that the growth of the molecular weight of the polymer, the porosity, the size of the pores, the Young modulus and maximum tensile increased. Additionally, to obtain a better morphology of the membranes, PVP should be added to the polymeric solution. Positive growth of L929 fibroblast cells on the obtained scaffolds was shown.

Keywords:
biodegradable polymers, cell cultures, L929 fibroblasts, polylactide, scaffolds, tissue engineering

54.Gadomska‐Gajadhur A., Kruk A., Ruśkowski P., Sajkiewicz P., Dulnik J., Chwojnowski A., Original method of imprinting pores in scaffolds for tissue engineering, Polymers for Advanced Technologies, ISSN: 1042-7147, DOI: 10.1002/pat.5091, pp.1-13, 2020
Gadomska‐Gajadhur A., Kruk A., Ruśkowski P., Sajkiewicz P., Dulnik J., Chwojnowski A., Original method of imprinting pores in scaffolds for tissue engineering, Polymers for Advanced Technologies, ISSN: 1042-7147, DOI: 10.1002/pat.5091, pp.1-13, 2020

Abstract:
Results of the preparation of biodegradable porous scaffolds using an original modification of a wet phase inversion method were presented. Influence of gelatin non‐woven as a non‐classic pore precursor and polyvinylpyrrolidone, Pluronic as classic pore precursors on the structure of obtained scaffolds was analyzed. It was shown that the addition of gelatin non‐wovens enables the preparation of scaffolds, which allow for the growth of cells (size, distribution, and shape of pores). Mechanical properties of the obtained cell scaffolds were determined. The influence of pore precursors on mass absorption of scaffolds against isopropanol and plasma was investigated. Interaction of scaffolds with a T‐lymphocyte line (Jurkat) and with fibroblasts (L929) was investigated. Obtained scaffolds are not cytotoxic and can be used as implants, for example, the regeneration of cartilage tissue.

Keywords:
cell cultures, cytotoxic, fibroblasts, imprinted scaffolds

55.Pietrzak K., Strojny-Nędza A., Kaszyca K., Shepa I., Mudra E., Vojtko M., Dusza J., Antal V., Hovancova J., Chmielewski M., Oxidation and corrosion resistance of NiCr-Re and NiCr-Re-Al2O3 materials fabricated by spark plasma sintering, Metals, ISSN: 2075-4701, DOI: 10.3390/met10081009, Vol.10, No.8, pp.1009-1-12, 2020
Pietrzak K., Strojny-Nędza A., Kaszyca K., Shepa I., Mudra E., Vojtko M., Dusza J., Antal V., Hovancova J., Chmielewski M., Oxidation and corrosion resistance of NiCr-Re and NiCr-Re-Al2O3 materials fabricated by spark plasma sintering, Metals, ISSN: 2075-4701, DOI: 10.3390/met10081009, Vol.10, No.8, pp.1009-1-12, 2020

Abstract:
The thermal and oxidation resistance of elements found in the combustion boilers of power generation plants are some of the most important factors deciding their effectiveness. This paper shows the experimental results of the influence of NiCr-based material composition on the microstructure and phase changes occurring during the oxidation and corrosion process. NiCr alloy was modified by the addition of rhenium and aluminum oxide. Materials were densified using the spark plasma sintering method at a sintering temperature of 1050 °C. Oxidation tests conducted up to 1100 °C under synthetic airflow revealed the formation of a thin Cr2O3 layer protecting the material against in-depth oxidation. Results of electrochemical corrosion in a 0.5 M NaCl solution indicated a positive role of Re and Al2O3 addition, confirmed by low corrosion current density values in comparison to the other reference materials. According to the provided positive preliminary test results, we can conclude that a NiCr-Re-Al2O3 system in coating form was successfully obtained by the plasma spraying method.

Keywords:
NiCr, rhenium, aluminium oxide, metal matrix composites, oxidation, corrosion

56.Gadomska‐Gajadhur A., Kruk A., Dulnik J., Chwojnowski A., New polyester biodegradable scaffolds for chondrocyte culturing: preparation, properties, and biological activity, JOURNAL OF APPLIED POLYMER SCIENCE, ISSN: 0021-8995, DOI: 10.1002/app.50089, pp.e50089-1-14, 2020
Gadomska‐Gajadhur A., Kruk A., Dulnik J., Chwojnowski A., New polyester biodegradable scaffolds for chondrocyte culturing: preparation, properties, and biological activity, JOURNAL OF APPLIED POLYMER SCIENCE, ISSN: 0021-8995, DOI: 10.1002/app.50089, pp.e50089-1-14, 2020

Abstract:
An innovative modification of the wet inversion phase method, consisting in the use of a polymer nano‐nonwoven as a nonclassic pore precursor. Mechanical properties of the obtained scaffolds were determined, their hydrophilic properties (serum absorbability) were tested, and the content of residues of materials used in the scaffold preparation was determined. Nontoxicity of the developed scaffolds toward T lymphocyte cells was proved. Cultures of primary chondrocytes were obtained successfully. It was proved that an addition of a polymer nano‐nonwoven changes the properties of the scaffolds favorably in respect of their subsequent application in tissue engineering.

Keywords:
cartilage regeneration, chondrocytes, nano-nonwoven, polyvinylpyrrolidone, T lymphocytes

57.Chatterjee P., Glimm T., Kaźmierczak B., Mathematical modeling of chondrogenic pattern formation during limb development: recent advances in continuous models, MATHEMATICAL BIOSCIENCES, ISSN: 0025-5564, DOI: 10.1016/j.mbs.2020.108319, Vol.322, pp.108319-1-17, 2020
Chatterjee P., Glimm T., Kaźmierczak B., Mathematical modeling of chondrogenic pattern formation during limb development: recent advances in continuous models, MATHEMATICAL BIOSCIENCES, ISSN: 0025-5564, DOI: 10.1016/j.mbs.2020.108319, Vol.322, pp.108319-1-17, 2020

Abstract:
The phenomenon of chondrogenic pattern formation in the vertebrate limb is one of the best studied examples of organogenesis. Many different models, mathematical as well as conceptual, have been proposed for it in the last fifty years or so. In this review, we give a brief overview of the fundamental biological background, then describe in detail several models which aim to describe qualitatively and quantitatively the corresponding biological phenomena. We concentrate on several new models that have been proposed in recent years, taking into account recent experimental progress. The major mathematical tools in these approaches are ordinary and partial differential equations. Moreover, we discuss models with non-local flux terms used to account for cell-cell adhesion forces and a structured population model with diffusion. We also include a detailed list of gene products and potential morphogens which have been identified to play a role in the process of limb formation and its growth.

Keywords:
mathematical models of chondrogenesis, reaction-diffusion equations, pattern formation, limb development

58.Fabbrocino F., Darban H., Luciano R., Nonlocal layerwise formulation for interfacial tractions in layered nanobeams, Mechanics Research Communications, ISSN: 0093-6413, DOI: 10.1016/j.mechrescom.2020.103595, Vol.109, pp.103595-1-5, 2020
Fabbrocino F., Darban H., Luciano R., Nonlocal layerwise formulation for interfacial tractions in layered nanobeams, Mechanics Research Communications, ISSN: 0093-6413, DOI: 10.1016/j.mechrescom.2020.103595, Vol.109, pp.103595-1-5, 2020

Abstract:
Interfacial tractions generated at the interface in two-layered nanobeams are studied through the stress-driven nonlocal theory of elasticity and an interface model. The model uses a layerwise description of the problem and satisfies the continuity conditions at the interface. The size-dependency are incorporated into formulation through a nonlocal constitutive law which defines the strain at each point as an integral convolution in terms of the stresses in all the points and a kernel. The Bernoulli-Euler beam theory is used separately for each layer to describe kinematic field, and to derive size-dependent system of coupled governing equations. The displacement components within the layers are derived and the interfacial tractions are obtained through the interfacial constitutive relations. Results are presented for the interfacial shear and normal tractions, exhibiting a different behavior at the nano-scale compared to those of the layered beams with large-scale dimensions including different maximum interfacial tractions and the location where maxima occur. A superior resistance of nanobeams against debondings and delaminations due to the interfacial normal tractions compared to that of the beams with large-scale dimensions is observed. The formulation and the understandings presented here are expected to stimulate further researches on multilayered nanobeams, including their interfacial fracture mechanics.

Keywords:
multilayered nanobeams, weak bonding, interfacial tractions, delamination, nonlocal elasticity

59.Fantilli A.P., Jóźwiak-Niedźwiedzka D., Influence of Portland cement alkalinity on wool reinforced mortar, Proceedings of the Institution of Civil Engineers - Construction Materials, ISSN: 1747-650X, DOI: 10.1680/jcoma.20.00003, pp.1-10, 2020
Fantilli A.P., Jóźwiak-Niedźwiedzka D., Influence of Portland cement alkalinity on wool reinforced mortar, Proceedings of the Institution of Civil Engineers - Construction Materials, ISSN: 1747-650X, DOI: 10.1680/jcoma.20.00003, pp.1-10, 2020

Abstract:
Natural wool is a good insulating material, both thermal and acoustic. Nevertheless, with the increase in demand for the use of waste materials, other applications, such as the use of wool as a fibre-reinforcement in mortars and concretes, have been found. Unfortunately, wool, like other natural organic materials, dissolve in alkaline environment and, consequently, the performances of the reinforcement cannot be guaranteed for a long time. To solve the above issue, three series of reinforced mortar beams, with various contents of alkalis in cement, are investigated herein. The chemical compatibility, and the effects of alkalinity on the mechanical performances, are investigated by testing the beams in three point bending and, subsequently, by analysing the microstructure of the mortars through a scanning electron microscope equipped with energy dispersive X-ray spectroscopy. The results reveal that the lower the alkalinity of the cement paste, the better the resistance of wool fibres in cementitious matrix, which guarantees larger post-cracking residual stresses in the wool reinforced mortars.

Keywords:
fibre-reinforcement, fracture & fracture mechanics, microstructure, waste valorisation

60.Proniewska K., Pręgowska A., Dołęga-Dołęgowski D., Dudek D., Immersive technologies as a solution for general data protection regulation in Europe and impact on the COVID-19 pandemic, Cardiology Journal, ISSN: 1897-5593, DOI: 10.5603/CJ.a2020.0102, pp.1-21, 2020
Proniewska K., Pręgowska A., Dołęga-Dołęgowski D., Dudek D., Immersive technologies as a solution for general data protection regulation in Europe and impact on the COVID-19 pandemic, Cardiology Journal, ISSN: 1897-5593, DOI: 10.5603/CJ.a2020.0102, pp.1-21, 2020

Abstract:
Background: General data protection regulation (GDPR) provides rules according to which data should be managed and processed in a secure and appropriate way for patient requirements and security. Currently, everyone in Europe is covered by GDPR. Thus, the medical practice also requires access to patient data in a safe and secure way. Methods: Holographic technology allows users to see everything visible ona computer screen in a new and less restricted way, i. e. without the limitations of traditional computers and screens. Results: In this study, a three-dimensional holographic doctors' assistant is designed and implemented in a way that meets the GDPR requirements. The HoloView application, which is tailored to run on Microsoft HoloLens, is proposed toallow display and access to personal data and so-called sensitive information of all individual patients without the risk that it will be presented to unauthorized persons. Conclusions: To enhance the user experience and remain consistent with GSPR, a holographic desk is proposed that allows displaying patient data and sensitive information only in front of the doctor's eyes using mixed reality glasses. Last but not least, it boasts of a reduction in infection risk for the staff during the COVID-19 pandemic, affording medical care to be carried out by as few doctors as possible.

Keywords:
augmented reality, mixed reality, pandemic

61.Garlinska M., Pręgowska A., Masztalerz K., Osial M., From mirrors to free-space optical communication-historical aspects in data transmission, Future Internet, ISSN: 1999-5903, DOI: 10.3390/fi12110179, Vol.12, No.11, pp.179-1-18, 2020
Garlinska M., Pręgowska A., Masztalerz K., Osial M., From mirrors to free-space optical communication-historical aspects in data transmission, Future Internet, ISSN: 1999-5903, DOI: 10.3390/fi12110179, Vol.12, No.11, pp.179-1-18, 2020

Abstract:
Fast communication is of high importance. Recently, increased data demand and crowded radio frequency spectrum have become crucial issues. Free-Space Optical Communication (FSOC) has diametrically changed the way people exchange information. As an alternative to wire communication systems, it allows efficient voice, video, and data transmission using a medium like air. Due to its large bandwidth, FSOC can be used in various applications and has therefore become an important part of our everyday life. The main advantages of FSOC are a high speed, cost savings, compact structures, low power, energy efficiency, a maximal transfer capacity, and applicability. The rapid development of the high-speed connection technology allows one to reduce the repair downtime and gives the ability to quickly establish a backup network in an emergency. Unfortunately, FSOC is susceptible to disruption due to atmospheric conditions or direct sunlight. Here, we briefly discuss Free-Space Optical Communication from mirrors and optical telegraphs to modern wireless systems and outline the future development directions of optical communication.

Keywords:
free-space optical communication, telecommunications, wireless communication, data transfer history, communication networks

62.Kochańczyk M., Grabowski F., Lipniacki T., Dynamics of COVID-19 pandemic at constant and time-dependent contact rates, MATHEMATICAL MODELLING OF NATURAL PHENOMENA, ISSN: 0973-5348, DOI: 10.1051/mmnp/2020011, Vol.15, pp.28-1-12, 2020
Kochańczyk M., Grabowski F., Lipniacki T., Dynamics of COVID-19 pandemic at constant and time-dependent contact rates, MATHEMATICAL MODELLING OF NATURAL PHENOMENA, ISSN: 0973-5348, DOI: 10.1051/mmnp/2020011, Vol.15, pp.28-1-12, 2020

Abstract:
We constructed a simple Susceptible−Exposed–Infectious–Removed model of the spread of COVID-19. The model is parametrised only by the average incubation period, τ, and two rate parameters: contact rate, β, and exclusion rate, γ. The rates depend on nontherapeutic interventions and determine the basic reproduction number, R0 = β/γ, and, together with τ, the daily multiplication coefficient in the early exponential phase, θ. Initial R0 determines the reduction of β required to contain the spread of the epidemic. We demonstrate that introduction of a cascade of multiple exposed states enables the model to reproduce the distributions of the incubation period and the serial interval reported by epidemiologists. Using the model, we consider a hypothetical scenario in which β is modulated solely by anticipated changes of social behaviours: first, β decreases in response to a surge of daily new cases, pressuring people to self-isolate, and then, over longer time scale, β increases as people gradually accept the risk. In this scenario, initial abrupt epidemic spread is followed by a plateau and slow regression, which, although economically and socially devastating, grants time to develop and deploy vaccine or at least limit daily cases to a manageable number.

Keywords:
basic reproduction number, novel coronavirus

63.Volpert V., Banerjee M., D Onofrio, Lipniacki T., Petrovskii S., Tran V.C., Coronavirus - Scientific insights and societal aspects, MATHEMATICAL MODELLING OF NATURAL PHENOMENA, ISSN: 0973-5348, DOI: 10.1051/mmnp/2020010 , Vol.15, pp.E2-1-8, 2020
Volpert V., Banerjee M., D Onofrio, Lipniacki T., Petrovskii S., Tran V.C., Coronavirus - Scientific insights and societal aspects, MATHEMATICAL MODELLING OF NATURAL PHENOMENA, ISSN: 0973-5348, DOI: 10.1051/mmnp/2020010 , Vol.15, pp.E2-1-8, 2020

Abstract:
In December 2019, the first case of infection with a new virus COVID-19 (SARS-CoV-2), named coronavirus, was reported in the city of Wuhan, China. At that time, almost nobody paid any attention to it. The new pathogen, however, fast proved to be extremely infectious and dangerous, resulting in about 3–5% mortality. Over the few months that followed, coronavirus has spread over entire world. At the end of March, the total number of infections is fast approaching the psychological threshold of one million, resulting so far in tens of thousands of deaths. Due to the high number of lives already lost and the virus high potential for further spread, and due to its huge overall impact on the economies and societies, it is widely admitted that coronavirus poses the biggest challenge to the humanity after the second World war. The COVID-19 epidemic is provoking numerous questions at all levels. It also shows that modern society is extremely vulnerable and unprepared to such events. A wide scientific and public discussion becomes urgent. Some possible directions of this discussion are suggested in this article.

Keywords:
COVID-19, epidemic progression, mathematical models, crisis management, open questions

64.Popławski B., Mikułowski G., Orłowska A., Jankowski Ł., On/off nodal reconfiguration for global structural control of ‎smart 2D frames, Journal of Applied and Computational Mechanics, ISSN: 2383-4536, DOI: 10.22055/jacm.2020.32454.2016, pp.1-9, 2020
Popławski B., Mikułowski G., Orłowska A., Jankowski Ł., On/off nodal reconfiguration for global structural control of ‎smart 2D frames, Journal of Applied and Computational Mechanics, ISSN: 2383-4536, DOI: 10.22055/jacm.2020.32454.2016, pp.1-9, 2020

Abstract:
This paper proposes an on/off semi-active control approach for mitigation of free structural vibrations, designed for application in 2D smart frame structures. The approach is rooted in the Prestress-Accumulation Release (PAR) control strategies. The feedback signal is the global strain energy of the structure, or its approximation in the experimental setup. The actuators take the form of on/off nodes with a controllable ability to transfer moments (blockable hinges). Effectiveness of the approach is confirmed in a numerical simulation, as well as using a laboratory experimental test stand.

Keywords:
structural reconfiguration, structural control, semi-active control, frame structures, controllable nodes‎

65.Szolc T., Pochanke A., Konowrocki R., Pisarski D., Suppression and control of torsional vibrations of the turbo-generator shaft-lines using rotary magneto-rheological dampers, VIRM, 12th International Conference on Vibrations in Rotating Machinery: Proceedings of the 12th Virtual Conference on Vibrations in Rotating Machinery (VIRM), 2020-01-14/01-15, London (GB), DOI: 10.1201/9781003132639, pp.201-211, 2020
Szolc T., Pochanke A., Konowrocki R., Pisarski D., Suppression and control of torsional vibrations of the turbo-generator shaft-lines using rotary magneto-rheological dampers, VIRM, 12th International Conference on Vibrations in Rotating Machinery: Proceedings of the 12th Virtual Conference on Vibrations in Rotating Machinery (VIRM), 2020-01-14/01-15, London (GB), DOI: 10.1201/9781003132639, pp.201-211, 2020

Abstract:
Torsional vibrations of steam turbo-generator rotor-shaft-lines coupled with bending vibrations of exhaust blades still constitute an important operational problem for this type of rotor-machines. Therefore, this work proposes a relatively simple approach for efficient suppression and control of transient and steady-state turbo-generator shaft torsional vibrations excited by short circuits in a generator or power-lines, faulty synchronization, negative sequence currents and by sub-synchronous resonances in the turbo-generator-electric network system. This target has been achieved by means of semi-actively controlled rotary dampers with the magneto-rheological fluid. Regular operation of such devices installed in a given turbo-generator rotor-shaft line enables suppression of dangerous torsional oscillations.

Keywords:
control of torsional vibrations, the turbo-generator, rotary magneto-rheological dampers, Bi-directional active torsional vibration damper,

66.Jóźwiak-Niedźwiedzka D., Gméling K., Harsányi I., Dziedzic K., Glinicki M.A., Assessment of long-lived residual radioisotopes in cement induced by neutron radiation, MATBUD'2020, MATBUD'2020 Scientific-Technical Conference: E-mobility, Sustainable Materials and Technologies, 2020-10-19/10-21, Kraków (PL), DOI: 10.1051/matecconf/202032201019, Vol.322, pp.01019-1-7, 2020
Jóźwiak-Niedźwiedzka D., Gméling K., Harsányi I., Dziedzic K., Glinicki M.A., Assessment of long-lived residual radioisotopes in cement induced by neutron radiation, MATBUD'2020, MATBUD'2020 Scientific-Technical Conference: E-mobility, Sustainable Materials and Technologies, 2020-10-19/10-21, Kraków (PL), DOI: 10.1051/matecconf/202032201019, Vol.322, pp.01019-1-7, 2020

Abstract:
During the decommissioning of nuclear power plants, a significant amount of cement based composites should be disposed as radioactive waste. The use of material with low-activation constituents could effectively reduce radioactivity of concrete. The subject of the paper is the content of trace elements with large activation cross section in concrete constituents due to their ability to be activated in radiation shielding structures. Various Portland cement specimens were subjected to elemental analysis by neutron activation analysis and prompt gamma activation analysis to assess the dominant long-lived residual radioisotopes. Concentrations of the radionuclides, such as Europium-152, Cobalt-60 and Caesium-134 were assessed. Their half-life time is 13.5, 5.27, and 2.07 years, respectively. On the basis of the obtained results, recommendations for cement selection for low-activation concrete are proposed in order to economize decommissioning cost by reducing a radioactive concrete waste.

67.Antolik A., Jóźwiak-Niedźwiedzka D., Dziedzic K., Bogusz K., Glinicki M.A., Microscopic analysis of the alkali-silica reactivity of various origin fine aggregate, MATBUD'2020, MATBUD'2020 Scientific-Technical Conference: E-mobility, Sustainable Materials and Technologies, 2020-10-19/10-21, Kraków (PL), DOI: 10.1051/matecconf/202032201025, Vol.322, pp.01025-1-8, 2020
Antolik A., Jóźwiak-Niedźwiedzka D., Dziedzic K., Bogusz K., Glinicki M.A., Microscopic analysis of the alkali-silica reactivity of various origin fine aggregate, MATBUD'2020, MATBUD'2020 Scientific-Technical Conference: E-mobility, Sustainable Materials and Technologies, 2020-10-19/10-21, Kraków (PL), DOI: 10.1051/matecconf/202032201025, Vol.322, pp.01025-1-8, 2020

Abstract:
Alkali silica reaction (ASR) is a harmful phenomenon occurring as a result of chemical interactions between sodium and potassium hydroxides in the pore solution and reactive minerals contained in the aggregate. Reactive minerals like microcrystalline, cryptocrystalline or strained quartz dissolve in the alkaline solution and form an expansive gel product. Proper selection of concrete constituents is necessary to ensure the durability of concrete structures. The proper recognition of the aggregate mineralogical composition is a very important element in the process of selection of concrete components due to the risk of ASR occurrence. This paper presents the results of detailed microscopic analysis of alkali-silica reactivity of domestic fine aggregates of various origins. Six siliceous sands from different locations in Poland and one limestone sand were tested. Detailed petrographic analysis was performed on thin sections. In all siliceous sands micro- and cryptocrystalline quartz was recognized as a reactive mineral. Digital image analysis was performed for quantitative assessment of the potential of reactivity of sands. It revealed, that siliceous river sands were the most susceptible to an alkali-silica reaction, which was confirmed by mortar bar expansion test performed according to the standard test method.

68.Zawidzki M., The Overview of Optimization Methods Applied to Truss-Z Modular System, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, DOI: 10.24423/cames.291, Vol.27, No.2-3, pp.155-176, 2020
Zawidzki M., The Overview of Optimization Methods Applied to Truss-Z Modular System, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, DOI: 10.24423/cames.291, Vol.27, No.2-3, pp.155-176, 2020

Abstract:
Extremely Modular Systems (EMSs) are comprised of as few types of modules as possible and allow creating structurally sound free-form structures that are not constrained by a regular tessellation of space. Truss-Z is the first EMS introduced, and its purpose is to create free-form pedestrian ramps and ramp networks in any given environment. This paper presents an overview of various multi-objective optimization methods applied to Truss-Z structures.

Keywords:
Truss-Z, extremely modular system, discrete optimization, multi-objective

69.Proniewska K., Pręgowska A., Walecki P., Dołęga-Dołęgowski D., Ferrari R., Dudek D., Overview of the holographic-guided cardiovascular interventions and training - a perspective, Bio-Algorithms and Med-Systems, ISSN: 1895-9091, DOI: 10.1515/bams-2020-0043, Vol.16, No.3, pp.20200043-1-9, 2020
Proniewska K., Pręgowska A., Walecki P., Dołęga-Dołęgowski D., Ferrari R., Dudek D., Overview of the holographic-guided cardiovascular interventions and training - a perspective, Bio-Algorithms and Med-Systems, ISSN: 1895-9091, DOI: 10.1515/bams-2020-0043, Vol.16, No.3, pp.20200043-1-9, 2020

Abstract:
Immersive technologies, like Virtual Reality (VR), Augmented Reality (AR) and Mixed Reality (MR) have undergone technical evolutions over the last few decades. Their rapid development and dynamic changes enable their effective applications in medicine, in fields like imaging, preprocedural planning, treatment, operations planning, medical students training, and active support during therapeutic and rehabilitation procedures. Within this paper, a comprehensive analysis of VR/AR/MR application in the medical industry and education is presented. We overview and discuss our previous experience with AR/MR and 3D visual environment and MR-based imaging systems in cardiology and interventional cardiology. Our research shows that using immersive technologies users can not only visualize the heart and its structure but also obtain quantitative feedback on their location. The MR-based imaging system proposed offers better visualization to interventionists and potentially helps users understand complex operational cases. The results obtained suggest that technology using VR/AR/MR can be successfully used in the teaching process of future doctors, both in aspects related to anatomy and clinical classes. Moreover, the system proposed provides a unique opportunity to break the boundaries, interact in the learning process, and exchange experiences inside the medical community.

Keywords:
augmented reality, improving the education process, interaction, intraprocedural visualization, mixed reality, preprocedural planning, teaching

70.Ahsani S., Boukadia R.F., Droz C., Zieliński T.G., Jankowski Ł., Claeys C., Desmet W., Deckers E., On the potential of meta-poro-elastic systems with small mass inclusions to achieve broad band a near-perfect absorption coefficient, ISMA2020 / USD2020, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2020-09-07/09-09, Leuven (BE), pp.2463-2472, 2020
Ahsani S., Boukadia R.F., Droz C., Zieliński T.G., Jankowski Ł., Claeys C., Desmet W., Deckers E., On the potential of meta-poro-elastic systems with small mass inclusions to achieve broad band a near-perfect absorption coefficient, ISMA2020 / USD2020, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2020-09-07/09-09, Leuven (BE), pp.2463-2472, 2020

Abstract:
This paper discusses the potential of meta-poro-elastic systems with small mass inclusions to create broadband sound absorption performance under the quarter-wavelength limit. A first feasibility study is done to evaluate whether embedding small mass inclusions in specific types of foam can lead to near-perfect absorption at tuned frequencies. This paper includes an optimization routine to find the material properties that maximize the losses due to the mass inclusion such that a near-perfect/perfect absorption coefficient can be achieved at specified frequencies. The near-perfect absorption is due to the mass-spring effect, which leads to an increase in the viscous loss. Therefore, it is efficient in the viscous regime. The well-known critical frequency, which depends on the porosity and flow resistivity of the material, is commonly used as a criteria to distinguish the viscous regime from the inertial regime. However, for the types of foam of interest to this work, the value of critical frequency is below the mass-spring resonance frequency. Hence, the inverse quality factor is used to provides a more accurate estimation on the frequency at which the transition from the viscous regime to the inertial regime.

71.Zieliński T.G., Venegas R., A multi-scale calculation method for sound absorbing structures with localised micro-porosity, ISMA2020 / USD2020, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2020-09-07/09-09, Leuven (BE), pp.395-407, 2020
Zieliński T.G., Venegas R., A multi-scale calculation method for sound absorbing structures with localised micro-porosity, ISMA2020 / USD2020, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2020-09-07/09-09, Leuven (BE), pp.395-407, 2020

Abstract:
This work presents a three-scale approach to modelling sound absorbing structures with non-uniform porosity, consisting of meso-patterns of localised micro-porosity. It can also be used for structures in which voids in a solid frame are filled with micro-fibres. The method involves double-scale, i.e. micro- and meso-scale, calculations of the effective properties of an equivalent homogenised medium, as well as macro-scale calculations of sound propagation and absorption in this medium, which at the macroscopic level can replace the entire absorbing structure of complex micro-geometry. The basic idea can be explained as follows: the mesoscale areas with localised micro-porosity are treated as homogenised meso-pores saturated with an equivalent visco-thermal fluid replacing the actual gas-saturated micro-porous medium, so that the macroscopic effective properties are finally calculated based on a simplified meso-scale geometry with homogenised mesopores.

72.Meissner M., Zieliński T.G., Low-frequency prediction of steady-state room response for different configurations of designed absorbing materials on room walls, ISMA2020 / USD2020, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2020-09-07/09-09, Leuven (BE), pp.463-477, 2020
Meissner M., Zieliński T.G., Low-frequency prediction of steady-state room response for different configurations of designed absorbing materials on room walls, ISMA2020 / USD2020, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2020-09-07/09-09, Leuven (BE), pp.463-477, 2020

Abstract:
A technique commonly used for improving room acoustics consists in increasing a total sound damping in a room. This objective can be achieved by using different configurations of a porous material for acoustical treatment of a room. In this work, that problem is analyzed theoretically by exploiting a modal representation of the impulse response (IR) function for steady-state sound field predictions. A formula for the IR function was obtained by solving a wave equation for an enclosure with complex-valued boundary conditions of walls. On the walls where the acoustic treatment is applied, these boundary conditions are related to the characteristic impedance, effective speed of sound and thickness of the porous material used for padding. Two different porous materials were considered in the analyses of the room with acoustic treatment, and to this end, the required effective properties were calculated for a rigid foam with a designed periodic microstructure, as well as for a poroelastic foam with specific visco-elastic properties of the skeleton.

73.Opiela K.C., Zieliński T.G., Attenborough K., Manufacturing, modeling, and experimental verification of slitted sound absorbers, ISMA2020 / USD2020, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2020-09-07/09-09, Leuven (BE), pp.409-420, 2020
Opiela K.C., Zieliński T.G., Attenborough K., Manufacturing, modeling, and experimental verification of slitted sound absorbers, ISMA2020 / USD2020, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2020-09-07/09-09, Leuven (BE), pp.409-420, 2020

Abstract:
Designs with uniformly distributed slits normal or inclined to the incident surface exhibit a great potential because of their simplicity and good acoustical performance. However, production of materials of this sort is challenging as the required fabrication precision is very high. This paper deals with additive manufacturing, modeling, and impedance tube testing of a few slitted geometries and their variations, including cases where the dividing walls between slits are perforated. They were designed to be producible with current 3D printing technology and provide reliable measurements using standardized equipment. The normal incidence sound absorption curves predicted analytically and numerically were verified experimentally. It is observed that such simple configurations may lead to absorption properties comparable to porous acoustic treatments with more complex microstructure. The good agreement between the predictions and measurements supports the validity of the multi-scale modeling employed.

74.Gupta A., Jain A., Kumari M., Tripathi S.K., Structural, electrical and electrochemical studies of sodium ion conducting blend polymer electrolytes, Materials Today: Proceedings, ISSN: 2214-7853, DOI: 10.1016/j.matpr.2020.05.030, pp.1-7, 2020
Gupta A., Jain A., Kumari M., Tripathi S.K., Structural, electrical and electrochemical studies of sodium ion conducting blend polymer electrolytes, Materials Today: Proceedings, ISSN: 2214-7853, DOI: 10.1016/j.matpr.2020.05.030, pp.1-7, 2020

Abstract:
In the present study sodium ion conducting polymer blend electrolytes has been prepared using poly (vinylidene fluoride – hexafluoro – propylene) (PVdF-HFP), poly (methyl methacrylate) (PMMA), and sodium thiocyanate (NaSCN) salt by solution-cast technique. The highest ionic conductivity of the optimized blend polymer electrolyte system [PVdF(HFP)-PMMA (4:1)] (20 wt%)-[NaSCN (1 M)] (80 wt%) has been found to be 4.54 × 10^−2 S cm^−1 at room temperature. The temperature dependence conductivity plot shows the Arrhenius behaviour and its activation energy calculated from the plot were found to be 0.13 eV. The structural and morphological studies of polymer blend electrolyte were investigated by XRD, SEM and FTIR spectroscopy. Complex formation between polymer and salt has been confirmed by these studies. The thermal properties of optimized electrolyte system were examined by differential scanning calorimetry (DSC) techniques. The ionic transport number was calculated using d.c polarization techniques and was found to be 0.92, which shows that electrolyte system is predominantly ionic in nature. The electrochemical potential window of optimized polymer blend electrolyte was tested and observed to be ~2.8 V.

Keywords:
polymer blends electrolyte, solution cast technique, sodium ion, FTIR, DSC

75.Fantilli A.P., Jóźwiak-Niedźwiedzka D., The effect of hydraulic cements on the flexural behavior of wool reinforced mortars, Academic Journal of Civil Engineering, ISSN: 2680-1000, DOI: 10.26168/icbbm2019.41, Vol.37, No.2, pp.287-292, 2020
Fantilli A.P., Jóźwiak-Niedźwiedzka D., The effect of hydraulic cements on the flexural behavior of wool reinforced mortars, Academic Journal of Civil Engineering, ISSN: 2680-1000, DOI: 10.26168/icbbm2019.41, Vol.37, No.2, pp.287-292, 2020

Abstract:
It is known that natural wool is a good thermal insulating material, but recent results suggest another application: the use of wool as a fiber-reinforcement in mortars and concretes. Indeed, the mechanical properties of wool filaments are comparable to those of some synthetic polymeric fibers (e.g., made with polypropylene). However, wool can dissolve in alkaline environments and, therefore, the performances of reinforced cement-based matrixes cannot be guaranteed for a long time. Accordingly, three series of reinforced mortar beams have been made with low alkali, high alkali, and sulfoaluminate cements. To investigate the chemical compatibility, and the subsequent effects on the mechanical performances, the beams have been tested in three point bending. As a result, the lower the alkalinity of the cement paste, the better the post-cracking capability of wool fibers to arrest the growth of cracks.

Keywords:
wool reinforcement, low alkali cement, high alkali cement, sulfoaluminate cement

76.Glinicki M.A., Materiałowe aspekty równości nawierzchni betonowej, DROGOWNICTWO, ISSN: 0012-6357, Vol.LXXV, No.4, pp.99-108, 2020
Glinicki M.A., Materiałowe aspekty równości nawierzchni betonowej, DROGOWNICTWO, ISSN: 0012-6357, Vol.LXXV, No.4, pp.99-108, 2020

Abstract:
Zgodnie z definicją podaną w MEPDG 2020, równość nawierzchni odzwierciedla profil nawierzchni w śladach kół. W artykule przestawiono przegląd materiałowych i technologicznych czynników wpływających na równość nawierzchni drogowej z betonu cementowego, dyblowanej i kotwionej, przeznaczonej do kategorii ruchu KR5-KR7. Omówiono specyfikę metody ślizgowej, która jest procesem ekstruzji betonu, pozwalającym na monolityczne ułożenie warstwy przy jednym przejeździe układarki. Omówiono właściwości reologiczne mieszanki betonowej oraz jej praktyczne cechy techniczne, mające decydujące znaczenie przy formowaniu powierzchni jezdni.Utrzymanie stałego profilu nawierzchni w projektowanym 30-letnim okresie eksploatacji jest możliwe dzięki wysokiej odporności betonu na silne oddziaływania mechaniczne, termiczne i agresję środowiska.
According to the definition given in MEPDG 2020, the evenness of pavement reflects the surface profile in the wheel tracks. A review of material and technological factors influencing the evenness of the road pavement made of cement concrete, doweled and anchored, designed for traffic category KR5-KR7 is presented. The specificity of the slip-form method, which is a process of concrete extrusion, allowing for monolithic paving at one pass of the paver is discussed. Rheological properties of the concrete mixture and its practical technical features, which are decisive for the formation of roadway surface, are discussed. Maintaining a constant surface profile over the designed 30-year service life is possible due to the high resistance of concrete to strong mechanical, thermal and environmental influences.

Keywords:
beton cementowy, IRI, MEPDG, metoda ślizgowa, nawierzchnia drogowa, projektowanie składu, równość, trwałość, właściwosci reologiczne cement concrete, IRI, MEPDG, sliding method, road pavement, composition design, evenness, durability, rheological properties

77.Proniewska K., Pręgowska A., Dołęga-Dołegowski D., Chmiel J., Dudek D., Three-dimensional operating room with unlimited perspective, MCSS 2020, 10th International Conference on Multimedia Communications, Services and Security, 2020-10-08/10-09, Kraków (PL), DOI: 10.1007/978-3-030-59000-0_26, Vol.1284, pp.351-361, 2020
Proniewska K., Pręgowska A., Dołęga-Dołegowski D., Chmiel J., Dudek D., Three-dimensional operating room with unlimited perspective, MCSS 2020, 10th International Conference on Multimedia Communications, Services and Security, 2020-10-08/10-09, Kraków (PL), DOI: 10.1007/978-3-030-59000-0_26, Vol.1284, pp.351-361, 2020

Abstract:
Apart fromoperating tables andmodern surgical instruments, themodern operating rooms are equipped with displays and video surveillance systems. The three-dimensional operating room allows users to watch medics perform surgery from different, individually chosen, points of view. For the first time, it is possible to reproduce/repeat the course of the operations and change the perspective or position, fromwhich it is observed. Here, we proposed a solution based on Microsoft HoloLens and Azure Kinect DK devices as remote support to patient management. The operating room is transferred to the digital form in real-time using Augmented Reality based technologies. Users can move around the digital place like a ghost in real space. The approach proposed allows users to see observe surgery from any point of view they want without disturbing the surgeon's workflow. They can change their positions, angle, and place of observation. All environmental restrictions disappear. The presented solution gives trainees a convenient opportunity to learn. It may make a significant contribution to improving the surgeontraining, patients' outcomes, and may allow virtual medical consultations during the surgery between specialists without them leaving their workplace.

Keywords:
3D operating room, augmented reality, HoloLens

78.Psiuk R., Wiśniewska M., Garbiec D., Mościcki T., Spiekanie iskrowo-plazmowe SPS borków wolframu z dodatkiem cyrkonu / Spark plasma sintering of zirconium alloyed tungsten borides, III Ogólnopolskie Seminarium Spark Plasma Sintering III National Workshop on Spark Plasma Sintering, 2020-10-23/10-23, Kraków (PL), pp.25-26, 2020
79.Chojnacki A., Konowrocki R., Wysocki G., Longitudinal dynamics of freight trains - experimental and theoretical investigations, RAIL VEHICLES 2020 , The 24th scientific conference RAIL VEHICLES 2020 , 2020-10-25/10-28, Arłamów - Ustrzyki Dolne/ Poland (PL), No.1, pp.41-42, 2020
Chojnacki A., Konowrocki R., Wysocki G., Longitudinal dynamics of freight trains - experimental and theoretical investigations, RAIL VEHICLES 2020 , The 24th scientific conference RAIL VEHICLES 2020 , 2020-10-25/10-28, Arłamów - Ustrzyki Dolne/ Poland (PL), No.1, pp.41-42, 2020

Abstract:
Safe operation and efficient of trains require assessment of its running behaviour. When freight rolling stock operators optimize their own costs and profits, one of many steps is to increase the number of wagons. As the freight trains become longer, the dynamics of individual freight wagons in the longitudinal direction becomes important in terms of in-service behaviour. In this case, the forces involved between the wagons have a key influence on safety against derailment. Safety against derailment is one of primary criteria for assessing the reliability of rail vehicle operation. The derailments of wagons of long freight trains frequently occurred around the world, which caused tremendous losses. Statistics from Australia, Canada, China revealed that the freight trains account for the vast majority of mainline derailments.

Keywords:
longitudinal dynamics, freight trains, experimental and theoretical investigations, trains dynamics, wheel-rail interaction

80.Kalinowski D., Konowrocki R., Szolc T., Marczewski A., Simulation research on safety against derailment of trams with independently rotating wheels, RAIL VEHICLES 2020 , The 24th scientific conference RAIL VEHICLES 2020 , 2020-10-25/10-28, Arłamów - Ustrzyki Dolne/ Poland (PL), No.1, pp.81-82, 2020
Kalinowski D., Konowrocki R., Szolc T., Marczewski A., Simulation research on safety against derailment of trams with independently rotating wheels, RAIL VEHICLES 2020 , The 24th scientific conference RAIL VEHICLES 2020 , 2020-10-25/10-28, Arłamów - Ustrzyki Dolne/ Poland (PL), No.1, pp.81-82, 2020

Abstract:
Trams with independently rotating wheels (IRW) enable to increase a comfort of traveling by lowering the floor level along the entire length of the vehicle, in particular above the bogies. In these trams such solution imposes a different design of motor bogies. In this construction of the bogies, four independent motors mounted on the bogie frame are connected each by a gear-stage with a single running-wheel. By means of the appropriate control algorithm guiding driving torques in curved sections of the railway track can be generated. Trams must ensure a high level of safety of passengers, and one of its aspect is safety against derailment. This article presents an original simulation method to investigate a level of safety against derailment for such vehicles. Principles of this method are independent of the tram car configuration. Using this approach, structural analysis of trams was carried out, which tested drive control in the boogie equipped with independently rotating wheels. Here, numerous simulations of motion on curved tracks were performed by means of various wheel drive control algorithms.

Keywords:
research safety, safety against derailment, derailment of trams, trams with independently rotating wheels, independently rotating wheels

81.Konowrocki R., Frischmut K., Analysis of acceleration signals measured obtained from a freight wagon in the various operation states, RAIL VEHICLES 2020 , The 24th scientific conference RAIL VEHICLES 2020 , 2020-10-25/10-28, Arłamów - Ustrzyki Dolne/ Poland (PL), No.1, pp.95-96, 2020
Konowrocki R., Frischmut K., Analysis of acceleration signals measured obtained from a freight wagon in the various operation states, RAIL VEHICLES 2020 , The 24th scientific conference RAIL VEHICLES 2020 , 2020-10-25/10-28, Arłamów - Ustrzyki Dolne/ Poland (PL), No.1, pp.95-96, 2020

Abstract:
In the present paper, the authors try to find distinguishable characteristics based on acceleration data obtained from a railway car body. Those quantities allow constructing diagnostic maps, which in turn can be used to classify vehicles clearly as damaged or undamaged. In this approach, the assessment is based on measurements taken from both an undamaged and damaged rail vehicle. The data are compared by methods of artificial intelligence. The aim of this paper is to study aspects of a pure signal-based approach to the end of a quick recognition of damage by assessment of selected parameters of sensor data in real time.

Keywords:
analysis of measured signals, experimental investigations, artificial intelligence, railway wagon, quick recognition of damage, damage diagnostic, neural networks

82.Szolc T., Pochanke A., Konowrocki R., Pisarski D., Suppression and control of torsional vibrations of the turbo-generator shaft-lines using rotary magneto-rheological dampers, VIRM, 12th International Conference on Vibrations in Rotating Machinery, 2020-01-14/01-15, London (GB), No.1, pp.90-90, 2020
Szolc T., Pochanke A., Konowrocki R., Pisarski D., Suppression and control of torsional vibrations of the turbo-generator shaft-lines using rotary magneto-rheological dampers, VIRM, 12th International Conference on Vibrations in Rotating Machinery, 2020-01-14/01-15, London (GB), No.1, pp.90-90, 2020

Abstract:
Torsional vibrations of steam turbo-generator rotor-shaft-lines coupled with bending vibrations of exhaust blades still constitute an important operational problem for this type of rotor-machines. Therefore, this work proposes a relatively simple approach for efficient suppression and control of transient and steady-state turbo-generator-shaft torsional vibrations excited by short circuits in a generator or power-lines, faulty synchronization, negative sequence currents and by sub-synchronous resonances in the turbo-generator-electric network system. This target has been achieved by means of semi-actively controlled rotary dampers with the magneto-rheological fluid. Regular operation of such devices installed in a given turbo-generator rotor-shaft-line enables suppression of dangerous torsional oscillations.

Keywords:
control of torsional vibrations, turbo-generator, shaft-lines vibrations, rotary magneto-rheological dampers, new rotary dampers

83.Kucharczyk K., Rybka J.D., Hilgendorff M., Krupinski M., Slachcinski M., Mackiewicz A., Giersig M., Dams-Kozlowska H., Composite spheres made of bioengineered spider silk and iron oxide nanoparticles for theranostics applications, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0219790, Vol.14, No.7, pp. e0219790-1-20, 2019
Kucharczyk K., Rybka J.D., Hilgendorff M., Krupinski M., Slachcinski M., Mackiewicz A., Giersig M., Dams-Kozlowska H., Composite spheres made of bioengineered spider silk and iron oxide nanoparticles for theranostics applications, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0219790, Vol.14, No.7, pp. e0219790-1-20, 2019

Abstract:
Bioengineered spider silk is a biomaterial that has exquisite mechanical properties, biocompatibility, and biodegradability. Iron oxide nanoparticles can be applied for the detection and analysis of biomolecules, target drug delivery, as MRI contrast agents and as therapeutic agents for hyperthermia-based cancer treatments. In this study, we investigated three bioengineered silks, MS1, MS2 and EMS2, and their potential to form a composite material with magnetic iron oxide nanoparticles (IONPs). The presence of IONPs did not impede the self-assembly properties of MS1, MS2, and EMS2 silks, and spheres formed. The EMS2 spheres had the highest content of IONPs, and the presence of magnetite IONPs in these carriers was confirmed by several methods such as SEM, EDXS, SQUID, MIP-OES and zeta potential measurement. The interaction of EMS2 and IONPs did not modify the superparamagnetic properties of the IONPs, but it influenced the secondary structure of the spheres. The composite particles exhibited a more than two-fold higher loading efficiency for doxorubicin than the plain EMS2 spheres. For both the EMS2 and EMS2/IONP spheres, the drug revealed a pH-dependent release profile with advantageous kinetics for carriers made of the composite material. The composite spheres can be potentially applied for a combined cancer treatment via hyperthermia and drug delivery.

84.Rybka J.D., Mieloch A.A., Plis A., Pyrski M., Pniewski T., Giersig M., Assembly and characterization of HBc derived virus-like particles with magnetic core, Nanomaterials, ISSN: 2079-4991, DOI: 10.3390/nano9020155, Vol.9, No.2, pp.155-1-11, 2019
Rybka J.D., Mieloch A.A., Plis A., Pyrski M., Pniewski T., Giersig M., Assembly and characterization of HBc derived virus-like particles with magnetic core, Nanomaterials, ISSN: 2079-4991, DOI: 10.3390/nano9020155, Vol.9, No.2, pp.155-1-11, 2019

Abstract:
Core-virus like particles (VLPs) assembly is a kinetically complex cascade of interactions between viral proteins, nanoparticle's surface and an ionic environment. Despite many in silico simulations regarding this process, there is still a lack of experimental data. The main goal of this study was to investigate the capsid protein of hepatitis B virus (HBc) assembly into virus-like particles with superparamagnetic iron oxide nanoparticles (SPIONs) as a magnetic core in relation to their characteristics. The native form of HBc was obtained via agroinfection of Nicotiana benthamiana with pEAQ-HBc plasmid. SPIONs of diameter of 15 nm were synthesized and functionalized with two ligands, providing variety in ζ-potential and hydrodynamic diameter. The antigenic potential of the assembled core-VLPs was assessed with enzyme-linked immunosorbent assay (ELISA). Morphology of SPIONs and core-VLPs was evaluated via transmission electron microscopy (TEM). The most successful core-VLPs assembly was obtained for SPIONs functionalized with dihexadecyl phosphate (DHP) at SPIONs/HBc ratio of 0.2/0.05 mg/mL. ELISA results indicate significant decrease of antigenicity concomitant with core-VLPs assembly. In summary, this study provides an experimental assessment of the crucial parameters guiding SPION-HBc VLPs assembly and evaluates the antigenicity of the obtained structures.

Keywords:
virus-like particles, VLPs, hepatitis B virus capsid protein, HBc, viral self-assembly, magnetic core, HBcAg

85.Brinkert K., Akay Ö., Richter M.H., Liedtke J., Fountaine K.T., Lewerenz H-J., Giersig M., Experimental methods for efficient solar hydrogen production in microgravity environment, Journal of Visualized Experiments, ISSN: 1940-087X, DOI: 10.3791/59122, Vol.154, pp.e59122-1-9, 2019
Brinkert K., Akay Ö., Richter M.H., Liedtke J., Fountaine K.T., Lewerenz H-J., Giersig M., Experimental methods for efficient solar hydrogen production in microgravity environment, Journal of Visualized Experiments, ISSN: 1940-087X, DOI: 10.3791/59122, Vol.154, pp.e59122-1-9, 2019

Abstract:
Long-term space flights and cis-lunar research platforms require a sustainable and light life-support hardware which can be reliably employed outside the Earth's atmosphere. So-called 'solar fuel' devices, currently developed for terrestrial applications in the quest for realizing a sustainable energy economy on Earth, provide promising alternative systems to existing air-revitalization units employed on the International Space Station (ISS) through photoelectrochemical water-splitting and hydrogen production. One obstacle for water (photo-) electrolysis in reduced gravity environments is the absence of buoyancy and the consequential, hindered gas bubble release from the electrode surface. This causes the formation of gas bubble froth layers in proximity to the electrode surface, leading to an increase in ohmic resistance and cell-efficiency loss due to reduced mass transfer of substrates and products to and from the electrode. Recently, we have demonstrated efficient solar hydrogen production in microgravity environment, using an integrated semiconductor-electrocatalyst system with p-type indium phosphide as the light-absorber and a rhodium electrocatalyst. By nanostructuring the electrocatalyst using shadow nanosphere lithography and thereby creating catalytic 'hot spots' on the photoelectrode surface, we could overcome gas bubble coalescence and mass transfer limitations and demonstrated efficient hydrogen production at high current densities in reduced gravitation. Here, the experimental details are described for the preparations of these nanostructured devices and further on, the procedure for their testing in microgravity environment, realized at the Bremen Drop Tower during 9.3 s of free fall.

Keywords:
chemistry, issue 154, solar fuels, hydrogen, microgravity, photoelectrocatalysis, drop tower, shadow nanosphere lithography, semiconductor-electrocatalyst systems

86.Akinoglu G.E., Akinoglu E.M., Kempa K., Giersig M., Plasmon resonances in coupled Babinet complementary arrays in the mid-infrared range, OPTICS EXPRESS, ISSN: 1094-4087, DOI: 10.1364/OE.27.022939, Vol.27, No.16, pp.22939-22950, 2019
Akinoglu G.E., Akinoglu E.M., Kempa K., Giersig M., Plasmon resonances in coupled Babinet complementary arrays in the mid-infrared range, OPTICS EXPRESS, ISSN: 1094-4087, DOI: 10.1364/OE.27.022939, Vol.27, No.16, pp.22939-22950, 2019

Abstract:
A plasmonic structure with transmission highly tunable in the mid-infrared spectra range is developed. This structure consists of a hexagonal array of metallic discs located on top of silicon pillars protruding through holes in a metallic Babinet complementary film. We reveal with FDTD simulations that changing the hole diameter tunes the main plasmonic resonance frequency of this structure throughout the infrared range. Due to the underlying Babinet physics of these coupled arrays, the spectral width of these plasmonic resonances is strongly reduced, and the higher harmonics are suppressed. Furthermore, we demonstrate that this structure can be easily produced by a combination of the nanosphere lithography and the metal-assisted chemical etching technique.

87.Henglein A., Giersig M., Formation of colloidal silver nanoparticles: capping action of citrate, JOURNAL OF PHYSICAL CHEMISTRY B, ISSN: 1520-6106, DOI: 10.1021/jp9925334, Vol.103, pp.9533-9539, 1999
Henglein A., Giersig M., Formation of colloidal silver nanoparticles: capping action of citrate, JOURNAL OF PHYSICAL CHEMISTRY B, ISSN: 1520-6106, DOI: 10.1021/jp9925334, Vol.103, pp.9533-9539, 1999

Abstract:
Colloidal silver sols of long-time stability are formed in the γ-irradiation of 1.0 x 10^-4 M AgClO4 solutions, which also contain 0.3 M 2-propanol, 2.5 x 10^-2 M N2O, and sodium citrate in various concentrations. The reduction of Ag+ in these solutions is brought about by the 1-hydroxyalkyl radical generated in the radiolysis of 2-propanol; citrate does not act as a reductant but solely as a stabilizer of the colloidal particles formed. Its concentration is varied in the range from 5.0 x 10^-5 to 1.5 x 10^-3 M, and the size and size distribution of the silver particles are studied by electron microscopy. At low citrate concentration, partly agglomerated large particles are formed that have many imperfections. In an intermediate range (a few 10^-4 M), wellseparated particles with a rather narrow size distribution and little imperfections are formed, the size slightly decreasing with increasing citrate concentration. At high citrate concentrations, large lumps of coalesced silver particles are present, due to destabilization by the high ionic strength of the solution. These findings are explained by two growth mechanisms: condensation of small silver clusters (type-I growth), and reduction of Ag+ on silver particles via radical-to-particle electron transfer (type-II growth). The particles formed in the intermediate range of citrate concentration were studied by high-resolution electron microscopy and computer simulations. They constitute icosahedra and cuboctahedra.

88.Liz-Marzán L.M., Giersig M., Mulvaney P., Synthesis of nanosized gold-silica core-shell particles, LANGMUIR, ISSN: 0743-7463, DOI: 10.1021/la9601871, Vol.12, No.18, pp.4329-4335, 1996
Liz-Marzán L.M., Giersig M., Mulvaney P., Synthesis of nanosized gold-silica core-shell particles, LANGMUIR, ISSN: 0743-7463, DOI: 10.1021/la9601871, Vol.12, No.18, pp.4329-4335, 1996

Abstract:
Gold colloids have been homogeneously coated with silica using the silane coupling agent (3-aminopropyl)- trimethoxysilane as a primer to render the gold surface vitreophilic. After the formation of a thin silica layer in aqueous solution, the particles can be transferred into ethanol for further growth using the Stöber method. The thickness of the silica layer can be completely controlled, and (after surface modification) the particles can be transferred into practically any solvent. Varying the silica shell thickness and the refractive index of the solvent allows control over the optical properties of the dispersions. The optical spectra of the coated particles are in good agreement with calculations using Mie's theory for core-shell particles.

89.Vossmeyer T., Katsikas L., Giersig M., Popovic G., Diesner K., Chemseddine A., Eychmüller A., Weller H., CdS nanoclusters: synthesis, characterization, size dependent oscillator strength, temperature shift of the excitonic transition energy, and reversible absorbance shift, JOURNAL OF PHYSICAL CHEMISTRY B, ISSN: 1520-6106, DOI: 10.1021/j100082a044, Vol.98, No.31, pp.7665-7673, 1994
Vossmeyer T., Katsikas L., Giersig M., Popovic G., Diesner K., Chemseddine A., Eychmüller A., Weller H., CdS nanoclusters: synthesis, characterization, size dependent oscillator strength, temperature shift of the excitonic transition energy, and reversible absorbance shift, JOURNAL OF PHYSICAL CHEMISTRY B, ISSN: 1520-6106, DOI: 10.1021/j100082a044, Vol.98, No.31, pp.7665-7673, 1994

Abstract:
Improved synthetic routes and size-selective precipitation have enabled the preparation of almost monodisperse CdS clusters. Six samples of 1-thioglycerol stabilized clusters with diameters of approximately 13,14,16,19, 23, and 39 A have been prepared as fully redispersible powders and were characterized by elemental analysis, powder X-ray diffraction, electron microscopy, thermogravimetric analysis, and UV-vis spectroscopy. Smallangle X-ray scattering was used to determine the mean cluster size. The well-structured UV-vis spectra reveal that the size-dependent shift of the 1s-1s excitonic transition is in agreement with the tight-binding theory and the pseudopotential theory. Moreover, as expected by quantum mechanical calculations the oscillator strength of the transition increases proportional to 1/r^3. UV-vis spectra taken at various temperatures between 4 and 295 K have shown that the temperature shift of the excitonic transition energy becomes stronger with decreasing particle size. Strong, reversible absorbance shifts were observed, upon transferring the clusters from their solutions onto quartz plates and vice versa.

90.Giersig M., Mulvaney P., Preparation of ordered colloid monolayers by electrophoretic deposition, LANGMUIR, ISSN: 0743-7463, DOI: 10.1021/la00036a014, Vol.9, No.12, pp.3408-3413, 1993
Giersig M., Mulvaney P., Preparation of ordered colloid monolayers by electrophoretic deposition, LANGMUIR, ISSN: 0743-7463, DOI: 10.1021/la00036a014, Vol.9, No.12, pp.3408-3413, 1993

Abstract:
Citrate- and alkanethiol-stabilized gold colloids have been electrophoretically deposited onto carboncoated copper grids. The colloid particles form ordered monolayers, and the core-to-core interparticle spacing is determined by the size of the alkane chains on the stabilizers used in the preparation of the sols. In the case of longer alkane chains, some interpenetration of the chains occurs when the gold particles form monolayers. When the gold sols are stabilized by sodium 3-thiopropionate, they can be reversibly coagulated and peptized by cycling the pH between 3 and 7. The method has also been used to form ordered monolayers and bilayers of latex particles.