Instytut Podstawowych Problemów Techniki
Polskiej Akademii Nauk

Najnowsze publikacje

Publikacje odnotowane przez trzy miesiące

1. Wieja K., Kiełczyński P., Szymański P., Szalewski M., Balcerzak A., Ptasznik S., Identification and investigation of mechanically separated meat (MSM) with an innovative ultrasonic method, Food Chemistry, ISSN: 0308-8146, DOI: 10.1016/j.foodchem.2020.128907, Vol.348, pp.128907-1-9, 2021nota 7068

Streszczenie:
An innovative analytical ultrasonic method for identification and investigation of Mechanically Separated Meat (MSM) samples is presented. To this end, the ultrasonic wave velocity (f = 5 MHz) in the investigated meat samples was measured. The measured ultrasonic velocity ranged from 1553.4 to 1589.9 m/s. The investigations were performed for: 1) minced hand deboned chicken fillets, 2) low pressure MSM from chicken carcasses, 3) low pressure MSM from chicken collarbones, 4) high pressure MSM from chicken carcasses and 5) high pressure MSM from chicken collarbones. Statistically significant (p < 0.001) differences in the ultrasonic velocity were observed for each of investigated kinds of meat. High significant correlations were found between the ultrasonic velocity and the content of protein, fat, sodium and density of the investigated meat. The applicability of the developed ultrasonic method for identifying various kinds of meat and to determine the content of protein, fat, sodium and density was demonstrated.

Słowa kluczowe:
physicochemical parameters, mechanically separated meat, ultrasonic velocity, protein content, calcium content, fat content

pdf 7068(200p.)
2. Tůma K., Rezaee Hajidehi M., Hron J., Farrell P.E., Stupkiewicz S., Phase-field modeling of multivariant martensitic transformation at finite-strain: computational aspects and large-scale finite-element simulations, COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, ISSN: 0045-7825, DOI: 10.1016/j.cma.2021.113705, Vol.377, pp.113705-1-23, 2021nota 7078

Streszczenie:
Large-scale 3D martensitic microstructure evolution problems are studied using a finite-element discretization of a finite-strain phase-field model. The model admits an arbitrary crystallography of transformation and arbitrary elastic anisotropy of the phases, and incorporates Hencky-type elasticity, a penalty-regularized double-obstacle potential, and viscous dissipation. The finite-element discretization of the model is performed in Firedrake and relies on the PETSc solver library. The large systems of linear equations arising are efficiently solved using GMRES and a geometric multigrid preconditioner with a carefully chosen relaxation. The modeling capabilities are illustrated through a 3D simulation of the microstructure evolution in a pseudoelastic CuAlNi single crystal during nano-indentation, with all six orthorhombic martensite variants taken into account. Robustness and a good parallel scaling performance have been demonstrated, with the problem size reaching 150 million degrees of freedom.

Słowa kluczowe:
phase-field method, finite-element method, large-scale simulations, shape memory alloys, nano-indentation

no pdf 7078(200p.)
3. Popławski B., Mikułowski G., Wiszowaty R., Jankowski Ł., Mitigation of forced vibrations by semi-active control of local transfer of moments, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2021.107733, Vol.157, pp.107733-1-16, 2021nota 7083

Streszczenie:
This paper proposes and tests a semi-active method for mitigation of random and harmonic forced vibrations of frame structures. The method is based on the Prestress Accumulation-Release (PAR) strategy, and it stimulates the transfer of vibration energy from low-order into high-order natural modes of vibration. Due to their high-frequency, the target high-order modes are efficiently mitigated by standard material damping mechanisms. The control is based on local reconfiguration of nodal ability to transfer moments between adjacent beams, which might be momentarily suppressed for selected nodes: performed at the maximum of the local bending strain, such a suppression stimulates a sudden release of the accumulated strain energy into high-frequency local and global vibrations. The effectiveness of the approach is confirmed numerically and experimentally in mitigation of low-frequency vibrations, including resonance conditions, of a slender planar frame structure subjected to harmonic, sweep and random forced excitations.

Słowa kluczowe:
damping of vibrations, smart structures, semi-active control, decentralized control, truss–frame nodes

no pdf 7083(200p.)
4. Meissner M., Application of modal expansion method for sound prediction in enclosed spaces subjected to boundary excitation, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2021.116041, Vol.500, pp.116041-1-18, 2021nota 7085

Streszczenie:
In this paper, the steady-state and transient sound fields inside 3D enclosed spaces were examined theoretically using the modal expansion method. An analytic formula for the Green's function was derived allowing to predict the interior sound field for both the harmonic and impulse boundary excitations. A theoretical model was tested numerically for a 3D car-like cavity with a sound absorbing material placed on walls. For a harmonic excitation, calculation results revealed high impact of a frequency and a sound damping on a distribution of the steady-state pressure amplitude. They also indicated irregularly located energy vortices in the active intensity vector field. Simulations of a transient sound field were carried out for a boundary excitation producing a sine wave pulse. Temporal changes in this field were studied using the pressure amplitude determined via the discrete Hilbert transform. A large temporal variability of a distribution of this amplitude was noted due to a strong dependence of a transient sound on a position of the observation point. Simulation results also shown that for a small sound damping on cavity walls, there was an intense sound reverberation inside the cavity.

Słowa kluczowe:
enclosed spaces, sound field prediction, modal expansion method, Green's function, sound intensity, reverberation time

no pdf 7085(200p.)
5. Rojek J., Nosewicz S., Thoeni K., 3D formulation of the deformable discrete element method, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.6666, pp.1-33, 2021nota 7101

Streszczenie:
This work presents a 3D extension of the deformable discrete element method (DDEM) developed previously for 2D problems. The 3D formulation employs spherical particles. The particle deformation is made up of a global and local deformation mode. The global mode is assumed to be produced by uniform stress due to the contact forces. Particle deformability yields a nonlocal contact model, in which one contact between particles is influenced by contacts with other particles. It also leads to the formation of new contacts in the particle assembly. The DDEM affects the behavior of the granular material at the macroscopic level and gives new possibilities in material modeling by the discrete element method (DEM). The new algorithm is verified on a unconfined uniaxial compression test of a cuboid specimen discretized with equal‐size bonded particles aligned in a simple cubic pattern using an analytical solution. Enhanced modeling capabilities are presented by simulating cylindrical specimens discretized with a nonuniform size of bonded particles. The micro–macro relationships for elastic parameters are obtained. It is shown that the DDEM extends the range of the Poisson's ratio achievable with the DEM. Additional simulations are performed to determine the stability limits of the DDEM.

Słowa kluczowe:
average stress, deformable particles, discrete element method, elastic constants, micro–macro relationships, nonlocal contact model

pdf 7101(200p.)
6. Łazarska M., Wozniak T.Z., Ranachowski Z., Trafarski A., Marciniak S., The use of acoustic emission and neural network in the study of phase transformation below MS, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14030551, Vol.14, No.3, pp.551-1-14, 2021nota 7062

Streszczenie:
Acoustic emission and dilatometry were applied to investigate the characteristics of phase transformations in bearing steel 100CrMnSi6-4 during austempering below the martensite start temperature (MS 175 °C) at 150 °C. The aim of this study is to characterize the product of transformation occurring below the MS temperature using various research methods. Analysis of the dilatometric curves shows that, after the formation of athermal martensite below the MS temperature, the austenite continues to undergo isothermal transformation, indicating the formation of bainite. Additionally, tests were carried out with the use of acoustic emission during isothermal hardening of the adopted steel. The obtained acoustic emission signals were analyzed using an artificial neural network. The results, in the form of a graph of the frequency of acoustic emission (AE) event occurrence as a function of time, make it possible to infer about the bainite isothermal transformation. The results of this research may be used in the future to design optimal heat treatment methods and, consequently, may enable desired microstructure shaping.

Słowa kluczowe:
bainite, austempering, acoustic emission, neural networks, dilatometry

pdf 7062(140p.)
7. Kochańczyk M., Lipniacki T., Pareto-based evaluation of national responses to COVID-19 pandemic shows that saving lives and protecting economy are non-trade-off objectives, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-021-81869-2, Vol.11, pp.2425-1-9, 2021nota 7067

Streszczenie:
Countries worldwide have adopted various strategies to minimize the socio-economic impact of the ongoing COVID-19 pandemic. Stringency of imposed measures universally reflects the standpoint from which protecting public health and avoiding damage to economy are seen as contradictory objectives. Based on epidemic trajectories of 25 highly developed countries and 10 US states in the (mobility reduction)–(reproduction number) plane we showed that delay in imposition of nation-wide quarantine elevates the number of infections and deaths, surge of which inevitably has to be suppressed by stringent and sustained lockdown. As a consequence, cumulative mobility reduction and population-normalized cumulative number of COVID-19-associated deaths are significantly correlated and this correlation increases with time. Overall, we demonstrated that, as long as epidemic suppression is the aim, the trade-off between the death toll and economic loss is illusory: high death toll correlates with deep and long-lasting lockdown causing a severe economic downturn.

pdf 7067(140p.)
8. Kaczmarek A., Hoffman J., Morgiel J., Mościcki T., Stobiński L., Szymański Z., Małolepszy A., Luminescent carbon dots synthesized by the laser ablation of graphite in polyethylenimine and ethylenediamine, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14040729, Vol.14, No.4, pp.729-1-13, 2021nota 7071

Streszczenie:
Fluorescent carbon dots (CDs) synthesized by pulsed laser ablation in liquid (PLAL) are still interesting materials due to their possible applications. However, unlike CDs produced by the hydrothermal method, CDs produced the synthesis products by the PLAL method were never separated by dialysis, which differentiates the synthesis products and allows the identification of the main source of fluorescence. In this work, the synthesis of fluorescent carbon dots (CDs) was performed by nanosecond laser ablation of a graphite target immersed in polyethyleneimine (PEI) and ethylenediamine (EDA), and the synthesis products were separated by dialysis. The results of optical measurements showed that the main source of luminescence of the obtained nanostructures are fluorescent particles or quasi-molecular fluorophores created in the ablation process. In the case of ablation in PEI, most of the produced molecular fluorophores are associated with carbogenic nanostructures, while in the case of EDA, free fluorescent molecules dominate.

Słowa kluczowe:
carbon dots, photoluminescence, laser ablation

no pdf 7071(140p.)
9. Dobruch-Sobczak K., Piotrzkowska-Wróblewska H., Klimonda Z., Karwat P., Roszkowska-Purska K., Clauser P., Baltzer P.A.T., Litniewski J., Multiparametric ultrasound examination for response assessment in breast cancer patients undergoing neoadjuvant therapy, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-021-82141-3, Vol.11, pp.2501 -1-9, 2021nota 7074

Streszczenie:
To investigate the performance of multiparametric ultrasound for the evaluation of treatment response in breast cancer patients undergoing neoadjuvant chemotherapy (NAC). The IRB approved this prospective study. Breast cancer patients who were scheduled to undergo NAC were invited to participate in this study. Changes in tumour echogenicity, stiffness, maximum diameter, vascularity and integrated backscatter coefficient (IBC) were assessed prior to treatment and 7 days after four consecutive NAC cycles. Residual malignant cell (RMC) measurement at surgery was considered as standard of reference. RMC < 30% was considered a good response and > 70% a poor response. The correlation coefficients of these parameters were compared with RMC from post-operative histology. Linear Discriminant Analysis (LDA), cross-validation and Receiver Operating Characteristic curve (ROC) analysis were performed. Thirty patients (mean age 56.4 year) with 42 lesions were included. There was a significant correlation between RMC and echogenicity and tumour diameter after the 3rd course of NAC and average stiffness after the 2nd course. The correlation coefficient for IBC and echogenicity calculated after the first four doses of NAC were 0.27, 0.35, 0.41 and 0.30, respectively. Multivariate analysis of the echogenicity and stiffness after the third NAC revealed a sensitivity of 82%, specificity of 90%, PPV = 75%, NPV = 93%, accuracy = 88% and AUC of 0.88 for non-responding tumours (RMC > 70%). High tumour stiffness and persistent hypoechogenicity after the third NAC course allowed to accurately predict a group of non-responding tumours. A correlation between echogenicity and IBC was demonstrated as well.

pdf 7074(140p.)
10. Dębska-Vielhaber G., Miller I., Peeva V., Zuschratter W., Walczak J., Schreiber S., Petri S., Machts J., Vogt S., Szczepanowska J., Gellerich F.N., Hermann A., Vielhaber S., Kunz W.S., Impairment of mitochondrial oxidative phosphorylation in skin fibroblasts of SALS and FALS patients is rescued by in vitro treatment with ROS scavengers, Experimental Neurology, ISSN: 0014-4886, DOI: 10.1016/j.expneurol.2021.113620, Vol.339, pp.113620-1-10, 2021nota 7075

Streszczenie:
Amyotrophic lateral sclerosis (ALS) is a devastating, rapidly progressive, neurodegenerative disorder affecting upper and lower motor neurons. Approximately 10% of patients suffer from familial ALS (FALS) with mutations in different ubiquitously expressed genes including SOD1, C9ORF72, TARDBP, and FUS. There is compelling evidence for mitochondrial involvement in the pathogenic mechanisms of FALS and sporadic ALS (SALS), which is believed to be relevant for disease. Owing to the ubiquitous expression of relevant disease-associated genes, mitochondrial dysfunction is also detectable in peripheral patient tissue. We here report results of a detailed investigation of the functional impairment of mitochondrial oxidative phosphorylation (OXPHOS) in cultured skin fibroblasts from 23 SALS and 17 FALS patients, harboring pathogenic mutations in SOD1, C9ORF72, TARDBP and FUS. A considerable functional and structural mitochondrial impairment was detectable in fibroblasts from patients with SALS. Similarly, fibroblasts from patients with FALS, harboring pathogenic mutations in TARDBP, FUS and SOD1, showed mitochondrial defects, while fibroblasts from C9ORF72 associated FALS showed a very mild impairment detectable in mitochondrial ATP production rates only. While we could not detect alterations in the mtDNA copy number in the SALS or FALS fibroblast cultures, the impairment of OXPHOS in SALS fibroblasts and SOD1 or TARDBP FALS could be rescued by in vitro treatments with CoQ10 (5 μM for 3 weeks) or Trolox (300 μM for 5 days). This underlines the role of elevated oxidative stress as a potential cause for the observed functional effects on mitochondria, which might be relevant disease modifying factors.

Słowa kluczowe:
amyotrophic lateral sclerosis, skin fibroblasts, mitochondrial dysfunction, oxidative stress

no pdf 7075(140p.)
11. Ostrowski M., Błachowski B., Popławski B., Pisarski D., Mikułowski G., Jankowski Ł., Semi‐active modal control of structures with lockable joints: general methodology and applications, STRUCTURAL CONTROL AND HEALTH MONITORING, ISSN: 1545-2255, DOI: 10.1002/stc.2710, Vol.28, No.5, pp.e2710-1-24, 2021nota 7076

Streszczenie:
In this study, a novel modal control strategy by means of semi-actively lockable joints is proposed. The control strategy allows for a directed flow of energy between vibrational modes, which makes it suitable not only for vibration attenuation purposes but also for energy scavenging driven by electromechanical energy harvesters. The proposed control strategy is an extension of the prestress-accumulation release (PAR) technique; however, it introduces also new concepts that increase the efficiency of the overall control system. Contrary to the PAR, the proposed method requires measurement of both strains in the vicinity of the semi-active joints and translational velocities that provide global information about system behavior. The latter aspect requires the control system to be organized within a hierarchical feedback architecture. The benefit from this higher complexity of the control system is its better performance compared to the PAR. The proposed semi-active modal control not only attenuates structural vibration faster, but it also achieves this goal with a smaller number of switches implemented in the joints. The effectiveness of the proposed methodology has been demonstrated on structures equipped with two lockable joints. Two practical examples have been investigated: one employs the concept of vibration-based energy harvesting for a two-story frame structure, while the second one reduces vibration of an eight-story frame structure subjected to kinematic excitation.

Słowa kluczowe:
energy harvesting, lockable joint, modal coupling, semi-active control, vibration attenuation

no pdf 7076(140p.)
12. Garbiec D., Wiśniewska M., Psiuk R., Denis P., Levintant-Zayonts N., Leshchynsky V., Rubach R., Mościcki T., Zirconium alloyed tungsten borides synthesized by spark plasma sintering, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-021-00188-5, Vol.21, pp.37-1-15, 2021nota 7080

Streszczenie:
Tungsten borides (WBx; x = 2.5 or 4.5) with an increasing substitution of tungsten by zirconium from 0 to 24 at.% were synthesized by spark plasma sintering (SPS) for the first time. The influence of the holding time (2.5–30 min) on the densification behavior, microstructure evolution and development of the properties of W–Zr–B compounds were studied. The samples were characterized using scanning electron microscopy (SEM) for microstructure analysis, X-ray diffraction (XRD) for phase identification, Vickers micro-indentation for microhardness measurements, tribological tests to determine the coefficient of friction and specific wear rate, as well as measurements of electrical conductivity. The XRD results confirm the presence of the WB4 phase in the microstructure, despite the high sintering temperature (1800 °C) and small overstoichiometric excess of boron (4.5) addition in the sintered samples. This is caused by the high heating rate (400 °C/min), short holding time (2.5 min) and addition of zirconium. The Vickers hardness (HV) values measured at 1 N are 24.8 ± 2.0 and 26.6 ± 1.8 GPa for 24 at.% zirconium in WB2.5 and for 0 at.% zirconium in WB4.5, respectively. In addition, the hardest sample (W0.76Zr0.24B2.5) showed electrical conductivity up to 3.961·10^6 S/m, which is similar to WC–Co cemented carbides. The friction and wear test results reveal the formation of a boron-based film which seems to play the role of a solid lubricant.

pdf 7080(140p.)
13. Zeller-Plumhoff B., Gile M., Priebe M., Słomińska H., Boll B., Wiese B., Würger T., Willumeit-Römer R., Horst Meißner R., Exploring key ionic interactions for magnesium degradation in simulated body fluid – a data-driven approach, Corrosion Science, ISSN: 0010-938X, DOI: 10.1016/j.corsci.2021.109272, Vol.182, pp.1-109272-13, 2021nota 7087

Streszczenie:
We have studied the degradation of pure magnesium wire in simulated body fluid and its subsets under physiological conditions to enable the prediction of the degradation rate based on the medium's ionic composition. To this end, micro-computed tomography and scanning electron microscopy with energy-dispersive X-ray spectroscopy were used, followed by a tree regression analysis. A non-linear relationship was found between degradation rate and the precipitation of calcium salts. The mean absolute error for predicting the degradation rate was 1.35 mm/yr. This comparatively high value indicates that ionic interactions were exceedingly complex or that an unknown parameter determining the degradation may exist.

Słowa kluczowe:
magnesium degradation, simulated body fluid, MicroCT, tree regression

no pdf 7087(140p.)
14. Gałęzia A., Orłowska-Gałęzia A., Application of Teager–Kaiser’s instantaneous frequency for detection of delamination in FRP composite materials, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14051154, Vol.14, No.5, pp.1154-1-24, 2021nota 7089

Streszczenie:
Composite materials are widely used in many engineering applications and fields of technology. One of the main defects, which occur in fiber-reinforced composite materials, is delamination. It manifests itself in the separation of layers of material and the damaged structure once subjected to mechanical loads degrades further. Delamination results in lower stiffness and the decrease of structure’s carry load capability. Its early detection is one of the tasks of non-invasive structural health monitoring of layered composite materials. This publication discusses a new method for delamination detection in fiber-reinforced composite materials. The approach is based on analysis of energy signal, calculated with Teager–Kaiser energy operator, and comparison of change of the weighted instantaneous frequency for measurement points located in- and outside of delamination area. First, applicability of the developed method was tested using simple models of vibration signals, reflecting considered phenomena. Next, the authors’ weighted instantaneous frequency was applied for detection of deamination using signals obtained from FEM simulated response of the cantilever beam. Finally, the methods effectiveness were tested involving real experimental signals collected by the laser Doppler vibrometer (LVD) sensor measuring vibrations of the delaminated glass-epoxy specimens.

Słowa kluczowe:
delamination, Teager–Kaiser energy operator, instantaneous frequency, fiber-reinforced composite material

pdf 7089(140p.)
15. Karwat P., Klimonda Z., Styczyński G., Szmigielski C., Litniewski J., Aortic root movement correlation with the function of the left ventricle, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-021-83278-x, Vol.11, pp.4473-1-8, 2021nota 7093

Streszczenie:
Echocardiographic assessment of systolic and diastolic function of the heart is often limited by image quality. However, the aortic root is well visualized in most patients. We hypothesize that the aortic root motion may correlate with the systolic and diastolic function of the left ventricle of the heart. Data obtained from 101 healthy volunteers (mean age 46.6 ± 12.4) was used in the study. The data contained sequences of standard two-dimensional (2D) echocardiographic B-mode (brightness mode, classical ultrasound grayscale presentation) images corresponding to single cardiac cycles. They also included sets of standard echocardiographic Doppler parameters of the left ventricular systolic and diastolic function. For each B-mode image sequence, the aortic root was tracked with use of a correlation tracking algorithm and systolic and diastolic values of traveled distances and velocities were determined. The aortic root motion parameters were correlated with the standard Doppler parameters used for the assessment of LV function. The aortic root diastolic distance (ARDD) mean value was 1.66 ± 0.26 cm and showed significant, moderate correlation (r up to 0.59, p < 0.0001) with selected left ventricular diastolic Doppler parameters. The aortic root maximal diastolic velocity (ARDV) was 10.8 ± 2.4 cm/s and also correlated (r up to 0.51, p < 0.0001) with some left ventricular diastolic Doppler parameters. The aortic root systolic distance (ARSD) was 1.63 ± 0.19 cm and showed no significant moderate correlation (all r values < 0.40). The aortic root maximal systolic velocity (ARSV) was 9.2 ± 1.6 cm/s and correlated in moderate range only with peak systolic velocity of medial mitral annulus (r = 0.44, p < 0.0001). Based on these results, we conclude, that in healthy subjects, aortic root motion parameters correlate significantly with established measurements of left ventricular function. Aortic root motion parameters can be especially useful in patients with low ultrasound image quality precluding usage of typical LV function parameters.

pdf 7093(140p.)
16. Kukla D., Kopeć M., Sitek R., Olejnik A., Kachel S., Kiszkowiak Ł., A novel method for high temperature fatigue testing of nickel superalloy turbine blades with additional NDT diagnostics, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14061392, Vol.14, No.6, pp.1392-1-17, 2021nota 7094

Streszczenie:
In this paper, a novel method for high temperature fatigue strength assessment of nickel superalloy turbine blades after operation at different times (303 and 473 h) was presented. The studies included destructive testing (fatigue testing at temperature 950 °C under cyclic bending load), non-destructive testing (Fluorescent Penetrant Inspection and Eddy Current method), and finite element modelling. High temperature fatigue tests were performed within load range from 5200 to 6600 N using a special self-designed blade grip attached to the conventional testing machine. The experimental results were compared with the finite element model generated from the ANSYS software. It was found that failure of turbine blades occurred in the area with the highest stress concertation, which was accurately predicted by the finite element (FE) model.

Słowa kluczowe:
nickel superalloys, high temperature fatigue, finite element (FE) modelling, eddy current

pdf 7094(140p.)
17. Długosz A., Pokorska I., Jaskulski R., Glinicki M.A., Evolutionary identification method for determining thermophysical parameters of hardening concrete, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-020-00154-7, Vol.21, pp.35-1-14, 2021nota 7095

Streszczenie:
The kinetics of heat transfer in hardening concrete is a key issue in engineering practice for erecting massive concrete structures. Prediction of the temperature fields in early age concrete should allow for proper control of the construction process to minimize temperature gradients and the peak temperatures, which is of particular importance for concrete durability. The paper presents a method of identification of the thermophysical parameters of early age concrete such as the thermal conductivity, the specific heat, and the heat generated by cement hydration in time. Proper numerical models of transient heat conduction problems were formulated by means of finite-element method, including two types of heat losses. The developed experimental–numerical approach included the transient temperature measurements in an isolated tube device and an in-house implementation of an evolutionary algorithm to solve the parameter identification task. Parametric Bezier curves were proposed to model heat source function, which allowed for identifying such function as a smooth curve utilizing a small number of parameters. Numerical identification tasks were solved for experimental data acquired on hardening concrete mixes differing in the type of cement and type of mineral aggregate, demonstrating the effectiveness of the proposed method (the mean-squared error less than 1 °C). The proposed approach allows for the identification of thermophysical parameters of early age concrete even for mixtures containing non-standard components while omitting drawbacks typical for classical optimization methods.

Słowa kluczowe:
early age concrete, evolutionary algorithm, inverse solution, heat transfer problem, mass concrete, thermal properties

no pdf 7095(140p.)
18. Czarnecka K., Wojasiński M., Ciach T., Sajkiewicz P., Solution blow spinning of polycaprolactone-rheological determination of spinnability and the effect of processing conditions on fiber diameter and alignment, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14061463, Vol.14, No.6, pp.1463-1-18, 2021nota 7097

Streszczenie:
The growing popularity of solution blow spinning as a method for the production of fibrous tissue engineering scaffolds and the vast range of polymer-solvent systems available for the method raises the need to study the effect of processing conditions on fiber morphology and develop a method for its qualitative assessment. Rheological approaches to determine polymer solution spinnability and image analysis approaches to describe fiber diameter and alignment have been previously proposed, although in a separate manner and mostly for the widely known, well-researched electrospinning method. In this study, a series of methods is presented to determine the processing conditions for the development of submicron fibrous scaffolds. Rheological methods are completed with extensive image analysis to determine the spinnability window for a polymer–solvent system and qualitatively establish the influence of polymer solution concentration and collector rotational speed on fiber morphology, diameter, and alignment. Process parameter selection for a tissue engineering scaffold target application is discussed, considering the varying structural properties of the native extracellular matrix of the tissue of interest.

Słowa kluczowe:
solution blow spinning, rheology, image analysis, nanofibers, fiber alignment, biodegradable nanofibers

pdf 7097(140p.)
19. Żuk P.J., Słowicka A.M., Ekiel-Jeżewska M.L., Stone H.A., Universal features of the shape of elastic fibres in shear flow, JOURNAL OF FLUID MECHANICS, ISSN: 0022-1120, DOI: 10.1017/jfm.2020.1048, Vol.914, pp.A31-1-41, 2021nota 7098

Streszczenie:
We present a numerical study of the dynamics of an elastic fibre in a shear flow at low Reynolds number, and seek to understand several aspects of the fibre's motion using the equations for slender-body theory coupled to the elastica. The numerical simulations are performed in the bead-spring framework including hydrodynamic interactions in two theoretical schemes: the generalized Rotne-Prager-Yamakawa model and a multipole expansion corrected for lubrication forces. In general, the two schemes yield similar results, including for the dominant scaling features of the shape that we identify. In particular, we focus on the evolution of an initially straight fibre oriented in the flow direction and show that the time scales of fibre bending, curling and rotation, which depend on its length and stiffness, determine the overall motion and evolution of the shapes. We document several characteristic time scales and curvatures representative of the shape that vary as power laws of the bending stiffness and fibre length. The numerical results are further supported by an interpretation using an elastica model.

Słowa kluczowe:
Stokesian dynamics, particle/fluid flow, slender-body theory

pdf 7098(140p.)
20. Glinicki M.A., Gołaszewski J., Cygan G., Formwork pressure of a heavyweight self-compacting concrete mix, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14061549, Vol.14, No.6, pp.1549-1-19, 2021nota 7104

Streszczenie:
High-fluidity and self-compacting concrete (SCC) mixes were developed using special aggregates for radiation-shielding concrete. The special aggregates comprised heavyweight and hydrous aggregates (crushed magnetite, crushed serpentine, and their mixtures), which were selected to provide an enhanced attenuation of gamma and neutron radiation, respectively. For the mixed concrete design with a bulk density of up to 3570 kg/m^3, two cement types were used: Portland cement CEM I and slag cement CEM III/A. The basic properties of the fresh self-compacting concrete were evaluated and the lateral formwork pressure exerted by the freshly mixed self-compacting concrete was measured and analyzed. An original test setup was developed for the determination of the lateral pressure on the square column formwork with pressure measurements carried out using six strain gauge pressure transducers, which was adequate for heavyweight concrete mixture testing. Self-compacting concrete mixtures containing a magnetite aggregate or blends of serpentine and magnetite aggregates with a slump flow of at least 550 mm were developed. The lateral pressure on the formwork was directly proportional to the density of the self-compacting heavyweight concrete mixes. The maximum values of the lateral pressure recorded in the test at a casting speed of 1.5 m/h did not exceed 27 kPa and 55% of hydrostatic pressure. Concrete mixtures with basalt, magnetite, and magnetite/serpentine blended aggregates were found to develop sufficient shear strength for proper stability during casting.

Słowa kluczowe:
Portland cement, consistency, formwork pressure, fresh mix, magnetite aggregate, mix design, radiation-shielding concrete, self-compacting concrete, serpentine aggregate, slag cement

no pdf 7104(140p.)
21. Widłaszewski J., Nowak Z., Kurp P., Effect of pre-stress on laser-induced thermoplastic deformation of Inconel 718 beams, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14081847, Vol.14, No.8, pp.1847-1-18, 2021nota 7105

Streszczenie:
Laser thermal forming is an application of laser heating without any intentional use of external forces. Force-assisted laser bending and laser-assisted bending are hybrid techniques, which combine the use of external forces and local heating to increase the effectiveness of forming. A quantitative description of bending deformation induced by concurrent laser heating and mechanical loading is proposed in this study. Mechanical loading is expressed by the bending moment while the curvature is used to describe the resulting deformation. The contribution of a relatively less known mechanism of laser thermal bending in the hybrid process is identified. The mechanism is able to produce the so-called convex deformation, i.e., bending away from the incident laser beam. Experimental and numerical analysis is performed with thin-walled beams made of Inconel 718 nickel-based superalloy in the factory-annealed state. The Johnson–Cook constitutive material model is used in numerical simulations validated by experimental results.

Słowa kluczowe:
laser bending, laser-assisted bending, Inconel 718, Johnson–Cook model, curvature

no pdf 7105(140p.)
22. Frydrych K., Libura T., Kowalewski Z., Maj M., Kowalczyk-Gajewska K., On the role of slip, twinning and detwinning in magnesium alloy AZ31B sheet, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, ISSN: 0921-5093, DOI: 10.1016/j.msea.2021.141152, Vol.813, pp.141151-1-14, 2021nota 7111

Streszczenie:
The paper reports experimental and numerical study of different deformation mechanisms activated in the AZ31B mag nesium alloy sheet subjected to cyclic in-plane tensile – compressive deformation. The influence ofslip, twinning and detwinning upon the mechanical response and texture evolution of the material is thoroughly investigated. The regime of twinning and detwinning activity is assessed based on the variation of hardening modulus in the course of the process. Velocity-based large strain crystal plasticity model accounting for twinning and detwinning is formulated. The crystal plasticity model parameters are identified using the implementation of the evolutionary algorithm. Predicted activity of deformation mechanisms is discussed with respect to the experimental data.

Słowa kluczowe:
twinning, detwinning, crystal plasticity, magnesium alloys, AZ31B, evolutionary algorithm

no pdf 7111(140p.)
23. Rezaee-Hajidehi M., Stupkiewicz S., Micromorphic approach to phase-field modeling of multivariant martensitic transformation with rate-independent dissipation effects, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2021.03.014, Vol.222-223, pp.111027-1-18, 2021nota 7119

Streszczenie:
A micromorphic formulation of the phase-field model of martensitic transformation is developed within the incremental energy minimization framework. In contrast to the conventional phase-field formulation, the order parameters are viewed as local variables and the corresponding evolution equations are solved at the material-point level, i.e. at the Gauss points in the finite-element setting. From a computational standpoint, such a treatment is advantageous for complex evolution laws that may lead to computational difficulties if treated globally, as in the conventional phase-field formulation. In the micromorphic formulation, each order parameter is coupled to its micromorphic counterpart governed by a global Helmholtz-type PDE. This coupling ensures that the interfacial energy and related size effects are correctly captured by the model. In this work, the micromorphic approach is applied to a finite-strain multivariant phase-field model that incorporates rate-independent dissipation. The augmented Lagrangian technique is then used to transform the resulting non-smooth incremental minimization problem to a smooth and unconstrained saddle-point problem. Microstructure evolution under nano-indentation is studied to illustrate the approach.

Słowa kluczowe:
phase-field method, micromorphic approach, rate-independent dissipation, incremental energy minimization, microstructure, shape-memory alloys

pdf 7119(140p.)
24. Mikułowski G., Popławski B., Jankowski Ł., Semi-active vibration control based on switchable transfer of bending moments: study and experimental validation of control performance, SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/1361-665X/abe33b, pp.1-22, 2021nota 7070

Streszczenie:
This paper presents an experimental approach to assessment of semi-active vibration control systems based on the Prestress-Accumulation Release concept. The objectives are threefold: 1) to introduce an experimental validation method for control algorithms based on switchable transfer of moments, 2) to propose a method to assess experimentally the control effects on structural dynamic response under several types of excitation, and 3) to propose an approach for adequate sensor placement. A laboratory frame demonstrator equipped with dedicated semi-active nodes is used. The proposed approach is based on spectral responses and modal analysis. According to the presented findings, the investigated control is effective in reducing the vibration level while keeping the structural dynamic stiffness at a proper level. The investigation is conducted in the case of free response, as well as responses to impact loading and random excitation. The results confirm the accuracy of the adopted algorithm parameters and reveal the sensor locations that provide the best control effectiveness.

no pdf 7070(100p.)
25. Ustrzycka A., Physical mechanisms based constitutive model of creep in irradiated and unirradiated metals at cryogenic temperatures, Journal of Nuclear Materials, ISSN: 0022-3115, DOI: 10.1016/j.jnucmat.2021.152851, Vol.548, pp.152851-1-15, 2021nota 7072

Streszczenie:
The present work describes the physical mechanisms of low temperature creep in irradiated and unirradiated metals. The slow inelastic deformations of solids under stress below the yield stress of the material are considered. For the problem of creep at cryogenic temperatures, the classical creep models are not enough. The purpose of this paper is to formulate a physically-based constitutive model of creep for irradiated materials at cryogenic temperatures (liquid nitrogen 77 K, liquid helium, 4.2 K) based on the idea that a dislocation held up by a potential barrier can pass through it owing to the quantum-mechanical tunnelling effect. The problem is novel in the context of recognition of physical mechanisms taking place at cryogenic temperatures leading to the evolution of radiation induced defects under mechanical loads. Creep produced by the expansion of irradiation induced dislocation loops is considered. The kinetic law for evolution of a dislocation loop is proposed using the mechanism of development of a dislocation line over Peierls stress hills. Also, creep produced by the elastic interaction of a radiation induced point defects with existing dislocations in materials is regarded. Predicted creep rate behaviour as a function of stresses and dpa are presented which would need to be validated with data in irradiated materials. Moreover, the new constitutive model of low temperature creep in unirradiated materials is formulated. The Glen-Mott quantum mechanical dislocation tunnelling effect allows extending the theory to the liquid helium temperature range. For this case of unirradiated materials, the creep curves validated experimentally for copper and stainless steel in cryogenic temperature are shown.

Słowa kluczowe:
creep in the proximity of absolute zero, irradiation creep, quantum-mechanical tunneling effect, cryogenic temperatures, low thermal energy, Peierls stress hills

no pdf 7072(100p.)
26. Marijnissen M.J., Graczykowski C., Rojek J., Simulation of the comminution process in a high-speed rotor mill based on the feed's macroscopic material data, Minerals engineering, ISSN: 0892-6875, DOI: 10.1016/j.mineng.2020.106746, Vol.163, pp.106746-1-11, 2021nota 7073

Streszczenie:
In this paper, we present a method that allows for the quick and efficient simulation of the comminution process in high-speed rotor mills. The method requires only the feed’s macroscopic material data and the geometry of the machine. Consisting of two stages, the method couples Computational Fluid Dynamics (CFD) with the Discrete Element Method (DEM) to obtain the collisional velocities and angles of a representative group of particles passing through the machine. Due to this coupling, any mill which relies on fluid forces acting on the ore particles can be simulated. After obtaining these values, the second stage commences wherein a single ore particle consisting of DEM elements collides against a rigid surface. The data obtained from this stage is then used to determine the minimum required working parameters of the chosen machine to achieve proper ore comminution. The proposed methodology was applied to analyse the novel concept of using beater mills for the comminution of copper ore.

Słowa kluczowe:
CFD, DEM, comminution modelling, particle breakage, beater mill, sandstone, copper ore

no pdf 7073(100p.)
27. Mahmood I., Poma Bernaola A., Okazaki K., Optimizing Gō-MARTINI coarse-grained model for F-BAR protein on lipid membrane, Frontiers in Molecular Biosciences, ISSN: 2296-889X, DOI: 10.3389/fmolb.2021.619381, Vol.8, pp.619381-1-10, 2021nota 7079

Streszczenie:
Coarse-grained (CG) molecular dynamics (MD) simulations allow us to access much larger length and time scales than atomistic MD simulations, providing an attractive alternative to the conventional simulations. Based on the well-known MARTINI CG force field, the recently developed Gō-MARTINI model for proteins describes large-amplitude structural dynamics, which has not been possible with the commonly used elastic network model. Using the Gō-MARTINI model, we conduct MD simulations of the F-BAR Pacsin1 protein on lipid membrane. We observe that structural changes of the non-globular protein are largely dependent on the definition of the native contacts in the Gō model. To address this issue, we introduced a simple cutoff scheme and tuned the cutoff distance of the native contacts and the interaction strength of the Lennard-Jones potentials in the Gō-MARTINI model. With the optimized Gō-MARTINI model, we show that it reproduces structural fluctuations of the Pacsin1 dimer from atomistic simulations. We also show that two Pacsin1 dimers properly assemble through lateral interaction on the lipid membrane. Our work presents a first step towards describing membrane remodeling processes in the Gō-MARTINI CG framework by simulating a crucial step of protein assembly on the membrane.

Słowa kluczowe:
Gō-MARTINI, protein complex, Pacsin, membrane remodeling, molecular dynamics, principal component analysis, RMSIP, assembly, protein contacts

pdf 7079(100p.)
28. Khmurovska Y., Štemberk P., Sikorin S., Němeček J., Jóźwiak-Niedźwiedzka D., Doleželová M., Kaladkevich Y., Pavalanski E., Fatseyeu V., Effects of gamma-ray irradiation on hardened cement mortar, International Journal of Concrete Structures and Materials, ISSN: 2234-1315, DOI: 10.1186/s40069-020-00452-7, Vol.15, pp.17-1-14, 2021nota 7086

Streszczenie:
The effect of gamma-ray irradiation on cement mortar properties is investigated in this study in order to understand the mechanism behind the strength and stiffness reduction, which may be significant according to the available researches. 60Co irradiation facility with the generating dose rate of 0.1–10 Gy/s and the total activity of 4.4·10^15 Bq (120 kCi) was used to perform the irradiation, so that the total observed dose of the irradiated samples reached the values ranging from 12.0 to 15.0 MGy. An identical set of control samples was placed in the same laboratory conditions away from gamma radiation. The results of nanoindentation, X-ray diffraction analysis and mercury intrusion porosimetry of the irradiated and the control samples are shown and explained in detail in this study. The nanoindentation creep compliance and the nanoindentation elastic modulus of the irradiated and the control samples do not show any significant difference. The mineral composition obtained using the X-ray diffraction analysis of the irradiated and the control samples is also similar. The pore structure rearrangement and microcrack occurrence, which were evidenced by the mercury intrusion porosimetry and scanning electron microscopy, led to the porosity increase and may be attributed to the significant decrease of compressive strength.

Słowa kluczowe:
cement mortar, drying, experiment, gamma-ray, nanoindentation, porosity, X-ray diffraction

pdf 7086(100p.)
29. Kovalchuk V., Gołubowska B., Mladenov I.M., Mechanics of infinitesimal gyroscopes on helicoid-catenoid deformation family of minimal surfaces, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 2300-1917, DOI: 10.24425/bpasts.2021.136727, Vol.69, No.2, pp.e136727-1-9, 2021nota 7088

Streszczenie:
In this paper we explore the mechanics of infinitesimal gyroscopes (test bodies with internal degrees of freedom) moving on an arbitrary member of the helicoid-catenoid family of minimal surfaces. As the configurational spaces within this family are far from being trivial manifolds, the problem of finding the geodesic and geodetic motions presents a real challenge. We have succeeded in finding the solutions of those motions in an explicit parametric form. It is shown that in both cases the solutions can be expressed through the elliptic functions and elliptic integrals, but in the geodetic case some appropriately chosen compatibility conditions for glueing together different branches of the solution are needed. Additionally, an action-angle analysis of the corresponding Hamilton-Jacobi equations is performed for external potentials that are well-suited to the geometry of the problem under consideration. As a result, five different sets of conditions between the three action variables and the total energy of the infinitesimal gyroscopes are obtained.

Słowa kluczowe:
action-angle analysis, mechanics of infinitesimal gyroscopes, geodesic and geodetic equations of motion, helicoid-catenoid deformation family of minimal surfaces, elliptic integrals and elliptic functions

no pdf 7088(100p.)
30. Nwaji N., Akinoglu E.M., Giersig M., Gold nanoparticle-decorated Bi2S3 nanorods and nanoflowers for photocatalytic wastewater treatment, Catalysts, ISSN: 2073-4344, DOI: 10.3390/catal11030355, Vol.11, No.3, pp.355-1-12, 2021nota 7092

Streszczenie:
Colloidal synthesis of photocatalysts with potential to overcome the drawback of low photocatalytic efficiency brought by charge recombination and narrow photo-response has been a challenge. Herein, a general and facile colloidal approach to synthesize orthorhombic phase Bi2S3 particles with rod and flower-like morphology is reported. We elucidate the formation and growth process mechanisms of these synthesized nanocrystals in detail and cooperate these Bi2S3 particles with metallic gold nanoparticles (AuNPs) to construct heterostructured photocatalysts. The unique properties of AuNPs featuring tunable surface plasmon resonance and large field enhancement are used to sensitize the photocatalytic activity of the Bi2S3 semiconductor particles. The morphology, structure, elemental composition, and light absorption ability of the prepared catalysts are characterized by (high-resolution) transmission electron microscopy, scanning electron microscopy, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, and UV–vis absorption spectroscopy. The catalysts exhibit high and stable photocatalytic activity for the degradation of organic pollutants demonstrated using rhodamine B and methyl orange dyes under solar light irradiation. We show that the incorporation of the AuNPs with the Bi2S3 particles increases the photocatalytic activity 1.2 to 3-fold. Radical trapping analysis indicates that the production of hydroxyl and superoxide radicals are the dominant active species responsible for the photodegradation activity. The photocatalysts exhibit good stability and recyclability.

Słowa kluczowe:
Bi2S3, nanoflower, nanorod, photocatalysis, heterostructures, AuNPs

pdf 7092(100p.)
31. Grabowski F., Preibisch G., Giziński S., Kochańczyk M., Lipniacki T., SARS-CoV-2 variant of concern 202012/01 has about twofold replicative advantage and acquires concerning mutations, Viruses, ISSN: 1999-4915, DOI: 10.3390/v13030392, Vol.13, No.3, pp.392-1-16, 2021nota 7096

Streszczenie:
The novel SARS-CoV-2 Variant of Concern (VOC)-202012/01 (also known as B.1.1.7), first collected in United Kingdom on 20 September 2020, is a rapidly growing lineage that in January 2021 constituted 86% of all SARS-CoV-2 genomes sequenced in England. The VOC has been detected in 40 out of 46 countries that reported at least 50 genomes in January 2021. We have estimated that the replicative advantage of the VOC is in the range 1.83–2.18 [95% CI: 1.71–2.40] with respect to the 20A.EU1 variant that dominated in England in November 2020, and in range 1.65–1.72 [95% CI: 1.46–2.04] in Wales, Scotland, Denmark, and USA. As the VOC strain will likely spread globally towards fixation, it is important to monitor its molecular evolution. We have estimated growth rates of expanding mutations acquired by the VOC lineage to find that the L18F substitution in spike has initiated a fast growing VOC substrain. The L18F substitution is of significance because it has been found to compromise binding of neutralizing antibodies. Of concern are immune escape mutations acquired by the VOC: E484K, F490S, S494P (in the receptor binding motif of spike) and Q677H, Q675H (in the proximity of the polybasic cleavage site at the S1/S2 boundary). These mutants may hinder efficiency of existing vaccines and expand in response to the increasing after-infection or vaccine-induced seroprevalence.

Słowa kluczowe:
COVID-19 pandemic, SARS-CoV-2, spike protein, VOC-202012/01, spike L18F, genome sequencing, mutation

pdf 7096(100p.)
32. Chernyshova M., Malinowski K., Jabłoński S., Casiraghi I., Demchenko I.N., Melikhov Y., Development of 2D GEM-based SXR plasma imaging for DTT device: focus on readout structure, Fusion Engineering and Design, ISSN: 0920-3796, DOI: 10.1016/j.fusengdes.2021.112443, Vol.169, pp.112443-1-12, 2021nota 7099

Streszczenie:
Creation and development of a new diagnostics useful for future thermonuclear reactors and helpful in studying impurity profiles, MHD modes/localization, and imaging are among urgent tasks in plasma research field. Global SXR imaging for DTT device in support of power exhaust programme and its consecutive impact for plasma core is an example of applicability of such diagnostics. This contribution presents the results of the ongoing development of the elaborated plasma X-ray imaging technology focusing on the design of the relevant structure of readout electrode. In order to achieve that, the details on the expected plasma radiation for the selected scenario for DTT machine were assessed. Then, the spatial distribution of plasma radiation intensity flux that will be reaching the detector window of the GEM based detector was simulated. Taking it into account along with the physical properties of the detector, the spatial and temporal distributions of charge cloud that will be reaching the readout plane were evaluated. The special design of the readout structure has been proposed that fulfil critical conditions originated from technological and physical constraints. The final effectiveness of the GEM based detector was evaluated proving that such detector is well suited for an effective plasma radiation imaging.

Słowa kluczowe:
X-ray detectors, GEM detector simulations, gas-electron multiplier (GEM) detector, SXR plasma imaging, DTT device

no pdf 7099(100p.)
33. Garlinska M., Pręgowska A., Gutowska I., Osial M., Szczepański J., Experimental study of the free space optics communication system operating in the 8–12 μm spectral range, Electronics , ISSN: 2079-9292, DOI: 10.3390/electronics10080875, Vol.10, No.8, pp.875-1-13, 2021nota 7103

Streszczenie:
(1) Background: Free space optics communication (FSO) has improved wireless communication and data transfer thanks to high bandwidth, low power consumption, energy efficiency, a high transfer capacity, and a wide applicability field. The FSO systems also have their limitations, including weather conditions and obstacles in the way of transmission. (2) Methods: This research assesses the atmospheric conditions’ influence on the intensity of received radiation, both experimentally and theoretically. The construction of a laboratory test stand of the FSO system, which is operating in the third-atmosphere transmission window (8–12 μm), is proposed. Next, considering different atmospheric conditions, the experimental validation was conducted, both in a laboratory and real conditions. (3) Results: The measurements were carried out for two optical links working with wavelengths of 1.5 μm and 10 μm. It was found that optical radiation with a wavelength of about 10 μm is characterized by better transmission properties in the case of limited visibility (e.g.,light rain and fogs) than in the case of near-infrared waves. The same conclusion was found in analytical investigations. (4) Conclusions: The results obtained show that optical radiation with a wavelength of about 10 μm in limited visibility is characterized by better transmission properties than near-infrared waves. This demonstrates the validity of designing FSO links operating in the range 8–12 μm band, e.g., based on quantum cascade lasers and HgCdTe photodiodes.

Słowa kluczowe:
free space optical communication, IR photodetector, quantum cascade laser, wireless communication

pdf 7103(100p.)
34. Taczała M., Buczkowski R., Kleiber M., Elastic-plastic buckling and postbuckling finite element analysis of plates using higher-order theory, International Journal of Structural Stability and Dynamics, ISSN: 1793-6764, DOI: 10.1142/S0219455421500954, pp.2150095-1-37, 2021nota 7106

Streszczenie:
In this paper, some of the displacement-based plate theories are used to investigate the elastic-plastic analysis of plates in the framework of the finite element method including the buckling and postbuckling effects with the focus on the general third-order plate theory (GTPT). The plate calculation results were compared with the results obtained using 64-nodes solid elements involving Lobatto integration scheme. The problem is solved using the Newton–Raphson method applying modified Crisfield constant arc-length procedure. The results show good agreement of results and the GTPT can be acknowledged to fulfill essential criteria for application to the elastic-plastic analysis of thin and thick plates.

Słowa kluczowe:
buckling and postbuckling, elasto-plastic plates, third-order plate theory

pdf 7106(100p.)
35. Niemczyk-Soczyńska B., Dulnik J., Jeznach O., Kołbuk D., Sajkiewicz P., Shortening of electrospun PLLA fibers by ultrasonication, Micron, ISSN: 0968-4328, DOI: 10.1016/j.micron.2021.103066, Vol.145, pp.103066-1-8, 2021nota 7107

Streszczenie:
This research work is aimed at studying the effect of ultrasounds on the effectiveness of fiber fragmentation by taking into account the type of sonication medium, processing time, and various PLLA molecular weights. Fragmentation was followed by an appropriate filtration in order to decrease fibers length distribution. It was evidenced by fiber length determination using SEM that the fibers are shortened after ultrasonic treatment, and the effectiveness of shortening depends on the two out of three investigated parameters, mostly on the sonication medium, and processing time. The gel permeation chromatography (GPC) confirmed that such ultrasonic treatment does not change the polymers' molecular weight. Our results allowed to optimize the ultrasonic fragmentation procedure of electrospun fibers while preliminary viscosity measurements of fibers loaded into hydrogel confirmed their potential in further use as fillers for injectable hydrogels for regenerative medicine applications.

Słowa kluczowe:
electrospinning, ultrasonication, short fibers, polymers

no pdf 7107(100p.)
36. Rojek I., Macko M., Mikałajewski D., Saga M., Burczyński T., Modern methods in the field of machine modelling and simulation as a research and practical issue related to industry 4.0, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 2300-1917, DOI: 10.24425/bpasts.2021.136717, pp.e136717-1-13, 2021nota 7110

Streszczenie:
Artificial intelligence (AI) is changing many areas of technology in the public and private spheres, including the economy. This report reviews issues related to machine modelling and simulations concerning further development of mechanical devices and their control systems as part of novel projects under the Industry 4.0 paradigm. The challenges faced by the industry have generated novel technologies used in the construction of dynamic, intelligent, flexible and open applications, capable of working in real time envi-ronments. Thus, in an Industry 4.0 environment, the data generated by sensor networks requires AI/CI to apply close-to-real-time data analysis techniques. In this way industry can face both fresh opportunities and challenges, including predictive analysis using computer tools capable of detecting patterns in the data based on the same rules that can be used to formulate the prediction.

Słowa kluczowe:
industry 4.0, Internet of Things, artificial intelligence, models, simulation

pdf 7110(100p.)
37. Dłużewski P., Domagala J.Z., Kret S., Jarosz D., Kryśko M., Phase-transition critical thickness of rocksalt MgxZn1−xO layers, The Journal of Chemical Physics, ISSN: 0021-9606, DOI: 10.1063/5.0042415, Vol.154, pp.154701-1-8, 2021nota 7116

Streszczenie:
The rocksalt structure of ZnO has a very promising bandgap for optoelectronic applications. Unfortunately, this high-pressure phase is unstable under ambient conditions. This paper presents experimental results for rocksalt-type ZnO/MgO superlattices and theoretical considerations of the critical thickness of MgxZn1−xO layers. The correlations between the layer/spacer thickness ratio, elastic strain, chemical composition, and critical thickness are analyzed. The Matthews and Blakeslee model is revisited to find analytic conditions for the critical layer thickness resulting in phase transition. Our analysis shows that due to the decrease in misfit stresses below some critical limit, the growth of multiple quantum wells composed of rocksalt ZnO layers and MgO spacers is possible only for very large layer/spacer thickness ratios.

no pdf 7116(100p.)
38. Pręgowska A., Masztalerz K., Garlińska M., Osial M., A worldwide journey through distance education-from the post office to virtual, augmented and mixed realities, and education during the COVID-19 pandemic, Education Sciences, ISSN: 2227-7102, DOI: 10.3390/educsci11030118, Vol.11, No.3, pp.118-1-26, 2021nota 7091

Streszczenie:
Surprisingly, distance education is quite an old concept. Its origins date back to the first correspondence-based course, which took place via the postal service in Boston, USA, in the 18th century. Rapid technological developments, especially in video and audio streaming, have increased the availability of such courses and moved learning into the virtual world. Due to the ongoing COVID-19 pandemic, we are witnessing an accelerated revolution in the learning process, as nearly all forms of education have been shifted online. Will this have a destructive effect on the human psyche? Is humanity sufficiently aware and ready for such a dramatic change? Will we return to physical in-classroom studies, or is remote distance education set to become the new norm? In particular, in medicine, computer science, fine arts, or architectural design, such a rapid change in the way students learn can be quite challenging. In this paper, we provide an overview of the history of distance learning, taking into account teachers’ and students’ points of view in both secondary and higher education.

Słowa kluczowe:
distance learning, distance education, online courses

pdf 7091(70p.)
39. Ghosal K., Augustine R., Zaszczyńska A., Barman M., Jain A., Hasan A., Kalarikkal N., Sajkiewicz P., Thomas S., Novel drug delivery systems based on triaxial electrospinning based nanofibers, REACTIVE AND FUNCTIONAL POLYMERS, ISSN: 1381-5148, DOI: 10.1016/j.reactfunctpolym.2021.104895, Vol.163, pp.104895-1-9, 2021nota 7109

Streszczenie:
Electrospinning is a widely investigated process for forming nanofibers. Nanofibers in drug delivery systems are extensively tested due to its remarkable properties e.g. small pore size or large surface area. Recent articles have informed about formation of fibers using triaxial electrospinning in drug delivery systems. This paper summarizes the process of triaxial electrospinning and its application in drug delivery. Triaxial electrospinning has advantages in forming complex nanostructures for specific drug delivery applications. This paper summarizes the possibility to use triaxial electrospinning to resolve the problem of limited drug solubility, to protect biomolecules from hostile environment, and to control drug release kinetics, with the possibility of loading of various drugs. There are literature data evidencing the possibility to achieve sustained release with a border case of zero rate order kinetics. There is no doubt that triaxial electrospinning opens a new way to develop sophisticated nanomaterials for achieving the desired functional performances and to expand the applications in the drug delivery area. Triaxial electrospinning method is interdisciplinary area with great potential in nanotechnology.

Słowa kluczowe:
triaxial electrospinning, complex nanostructures, drug delivery, desired functional performance, sustained/controlled release

no pdf 7109(70p.)
40. Pietrzak K., Gładki A., Strojny-Nędza A., Wejrzanowski T., Kaszyca K., Analysis of isotropy and uniformity of the distribution ofreinforcing phase in Cu/SiC composite materials using MCT methods, Image Analysis & Stereology, ISSN: 1580-3139, DOI: 10.5566/ias.1911, Vol.40, No.1, pp.39-47, 2021nota 7112

Streszczenie:
Tomography allows embedding of one space in another, especially ℛ2→ℛ3, and observation of the nature of the volumetric internal composite structure. Now, not only a simple interpretation is expected of geometry defined via single thresholds of structures. The binary segmentation used for numerical struc-ture analysis requires more detailed presentation. This paper shows an example of image analysis tech-niques applied to study the homogeneity of two-phase material. Using tomography analysis, the results of the homogeneity of the SiC particles with 10vol.%, 20vol.%, 30vol.%, 40vol.% volumetric bulk density of Cu/SiC composites are presented. Finally, for two independent coordinate systems, the distribution of SiC particle masses and their total moments of inertia were determined. The results confirmed that for well-mixed composite powders the homogeneity of the reinforcing phase is expected in samples with a SiC volume near 30vol.%. In this case, segregation by translation and rotation of SiC particles in the matrix, during the sintering process is restricted.

Słowa kluczowe:
Cu/SiC composite materials, image analysis, isotropy, uniformity

no pdf 7112(70p.)
41. Liu Z., Moreira R., Dujmović A., Liu H., Yang B., Poma Bernaola A., Nash M., Mapping mechanostable pulling geometries of protein-ligand complexes, 65th Annual Meeting of the Biophysical Society, 2021-02-22/02-26, virtual meeting (US), DOI: 10.1016/j.bpj.2020.11.2233, pp.362a, 2021nota 7081

Streszczenie:
Anticalin is a non-immunoglobulin protein scaffold with potential as an alternative to monoclonal antibodies for nanoparticle-based drug delivery to cells displaying cytotoxic T-lymphocyte antigen 4 (CTLA-4). In this context, one limiting factor is the resistance of the anticalin:CTLA-4 complex to mechanical forces exerted by fluid shear stress. Here, we used single-molecule AFM force spectroscopy to screen residues along the anticalin backbone and determine the optimal pulling point that achieves maximum mechanical stability of the anticalin:CTLA-4 complex. We used non-canonical amino acid incorporation by amber suppression in the anticalin combined with click chemistry to attach an Fgβ peptide at internal residues of the anticalin. We then used the Fgβ peptide as a handle to mechanically dissociate anticalin from CTLA-4 by applying tension at 8 different anchor residues, and measure the unbinding energy landscape for each pulling geometry. We found that pulling from amino acid position 60 on the anticalin resulted in ∼100% higher mechanical stability of the complex as compared with either the N- or C-terminus. Molecular dynamics (MD) simulations using the coarse-grained Martini force field showed strong agreement with experiments and help explain the mechanisms underlying the geometric dependency of mechanical stability in this therapeutic molecular complex. These results demonstrate that the mechanical stability of receptor-ligand complexes can be optimized by controlling the loading geometry without making any changes to the binding interface.

pdf 7081
42. Bogin B., Fairfield M., Goncalves R., Jarquin K., Jones S., Lovenduski C., Marin K., Webb E., Vargas H., Poma Bernaola A., Biais N., Baker J.L., Filaments under force: a computational molecular-scale investigation of type IV Pili from multiple organisms, 65th Annual Meeting of the Biophysical Society, 2021-02-22/02-26, virtual meeting (US), DOI: 10.1016/j.bpj.2020.11.1886, pp.294a, 2021nota 7082

Streszczenie:
Type IV pili (T4P) are biopolymers comprised of many protein subunits called pilin. These pilin subunits are not covalently bonded to one another, however remarkably T4P filaments are very strong and flexible. T4P emanate from the surface of prokaryotic cells and are utilized for many functions, including biofilm formation, surface adhesion, motility, and infection. The recent cryo-EM based structures for T4P from Escherichia coli, Neisseria meningitidis, Pseudomonas aeruginosa, and Neisseria gonorrhoeae have provided unprecedented insights into the structures of these filaments. However, although the structures of T4P are known, the dynamics of these filaments at the molecular scale at equilibrium and under tensile forces is not well characterized. In this work we provide an overview of our research into these various T4P filaments and their constituent pilin monomers under force. Specifically we carried out steered molecular dynamics simulations using a multiscale approach encompassing all-atom simulations and two levels of coarse-grained simulation. We have analyzed the changes in secondary structure of pilin subunits, global changes in filament architecture, and calculated the Young's modulus of each of the different T4P filaments. By drawing comparisons between all of these filament systems, we are able to obtain a broader picture of T4P dynamics than experimental structures alone can provide. In particular, we observe elongation of the alpha helix region of pilin subunits in each of these systems, which has been previously attributed to T4P flexibility and strength.

Słowa kluczowe:
filament, molecular dynamics, coarse graining, T4P

pdf 7082
43. Raef M., Hosseini S.M., Nabavian Kalat M., Razzaghi-Kashani M., Vulcanization kinetics of styrene butadiene rubber reinforced by graphenic particles, SPE Polymers, ISSN: 2690-3857, DOI: 10.1002/pls2.10039, pp.1-12, 2021nota 7090

Streszczenie:
The present study discusses the effects of graphenic particles on the kinetics of sulfur vulcanization in styrene butadiene rubber composites. Using data obtained from a cure rheometer and fitted by an autocatalytic model, it was verified that graphenic particles follow our recently established catalytic-networking model for the effect of particles on the sulfur vulcanization of rubber, regardless of the type of particles. The magnitude of the catalytic and networking effects depends on surface chemistry and interfacial interactions of particles with rubber that can be tailored by the chemical reduction of graphene oxide. Accordingly, the reduction process decreased the catalytic effect due to the elimination of surface functional groups and increased the networking effect due to the enhancement of filler–rubber interactions and immobilization of rubber. The latter was verified by differential scanning calorimetry and bound rubber measurements.

Słowa kluczowe:
graphene oxide, interfacial interactions, rubber composites, surface chemistry, vulcanization kinetics, wettability

pdf 7090
44. Glinicki M.A., Jóźwiak-Niedźwiedzka D., Reaktywność kruszywa w betonie, Materiały Budowlane, ISSN: 0137-2971, Vol.3, No.583, pp.51-54, 2021no pdf 7100
45. Pręgowska A., Warczak M., Osial M., Superparamagnetyczne nanocząstkina bazie tlenku żelaza domieszkowane terbem i modyfikowane aklarubicynądo magnetycznej hipertermii, XIII Interdyscyplinarna Konferencja Naukowa TYGIEL 2021 „Interdyscyplinarność kluczem do rozwoju”, 2021-03-25/03-28, Lublin (PL), pp.296, 2021pdf 7102
46. Marszałek A., Burczyński T., Forecasting day-ahead spot electricity prices using deep neural networks with attention mechanism, Journal of Smart Environments and Green Computing, ISSN: 2767-6595, DOI: 10.20517/jsegc.2021.02, Vol.1, pp.21-31, 2021nota 7108

Streszczenie:
This paper presents a novel approach to forecast hourly day-ahead electricity prices. In recent years, many predictive models based on statistical methods and machine learning (deep learning) techniques have been proposed. However, the approach presented in this paper focuses on the problem of constructing a fair and unbiased model. In this considered case, unbiased means that the model can increase prediction accuracy and decrease categorical bias across different data clusters. For this purpose, a model combining techniques such as long short-term memory (LSTM) recurrent neural network, attention mechanism, and clustering is created. The proposed model’s main feature is that the attention weights for LSTM hidden states are calculated considering a context vector given for each sample individually as the cluster center to which the sample belongs. In training mode, the samples are iteratively (one time per epoch) clustered based on representation vectors given by the attention mechanism. In the empirical study, the proposed model was applied and evaluated on the Nord Pool market data. To confirm that the model decreases categorical bias, the obtained results were compared with results of similar LSTM models but without the proposed attention mechanism.

Słowa kluczowe:
deep learning, electricity prices forecasting, time series forecasting, attention mechanism, debiasing, Nord Pool data

pdf 7108

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