Publications reported by three months

1.Adimy M., Chekroun A., Kaźmierczak B., Traveling waves in a coupled reaction–diffusion and difference model of hematopoiesis, Journal of Differential Equations, ISSN: 0022-0396, DOI: 10.1016/j.jde.2016.12.009, Vol.262, No.7, pp.4085-4128, 2017
Adimy M., Chekroun A., Kaźmierczak B., Traveling waves in a coupled reaction–diffusion and difference model of hematopoiesis, Journal of Differential Equations, ISSN: 0022-0396, DOI: 10.1016/j.jde.2016.12.009, Vol.262, No.7, pp.4085-4128, 2017

Abstract:
The formation and development of blood cells is a very complex process, called hematopoiesis. This process involves a small population of cells called hematopoietic stem cells (HSCs). The HSCs are undifferentiated cells, located in the bone marrow before they become mature blood cells and enter the blood stream. They have a unique ability to produce either similar cells (self-renewal), or cells engaged in one of different lineages of blood cells: red blood cells, white cells and platelets (differentiation). The HSCs can be either in a proliferating or in a quiescent phase. In this paper, we distinguish between dividing cells that enter directly to the quiescent phase and dividing cells that return to the proliferating phase to divide again. We propose a mathematical model describing the dynamics of HSC population, taking into account their spatial distribution. The resulting model is a coupled reaction–diffusion equation and difference equation with delay. We study the existence of monotone traveling wave fronts and the asymptotic speed of spread.

Keywords:
Hematopoiesis, Age-structured population, Reaction–diffusion system with delay, Difference equation, Traveling wave front, Asymptotic speed of spread

2.Krajewski M., Lee P.H., Wu S.H., Brzozka K., Małolepszy A., Stobiński L., Tokarczyk M., Kowalski G., Wąsik D., Nanocomposite composed of multiwall carbon nanotubes covered by hematite nanoparticles as anode material for Li-ion batteries, Electrochimica Acta, ISSN: 0013-4686, DOI: 10.1016/j.electacta.2017.01.051, Vol.228, pp.82-90, 2017
Krajewski M., Lee P.H., Wu S.H., Brzozka K., Małolepszy A., Stobiński L., Tokarczyk M., Kowalski G., Wąsik D., Nanocomposite composed of multiwall carbon nanotubes covered by hematite nanoparticles as anode material for Li-ion batteries, Electrochimica Acta, ISSN: 0013-4686, DOI: 10.1016/j.electacta.2017.01.051, Vol.228, pp.82-90, 2017

Abstract:
This work describes the detailed studies performed on the nanocomposite composed of chemically-modified multiwall carbon nanotubes covered by hematite nanoparticles which diameters vary from 10 nm to 70 nm. This nanomaterial was fabricated in two-steps facile chemical synthesis and was characterized with the use of several experimental techniques, such as: thermogravimetric analysis, differential thermal analysis, Raman spectroscopy, X-ray diffraction, and transmission Mössbauer spectroscopy in order to determine its structure precisely. Moreover, the investigated nanocomposite was tested as an anode material of Li-ion batteries. Its cycling performance was stable during 40 cycles, while its capacity was retained at the level of 330 and 230 mAh/g at the discharge/charge rate of 25 and 200 mA/g, respectively.

Keywords:
anode material, hematite, Li-ion battery, multiwall carbon nanotube, nanocomposite

3.Jarząbek D.M., Milczarek M., Wojciechowski T., Dziekoński C., Chmielewski M., The effect of metal coatings on the interfacial bonding strength of ceramics to copper in sintered Cu-SiC composites, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2017.01.056, pp.1-9, 2017
Jarząbek D.M., Milczarek M., Wojciechowski T., Dziekoński C., Chmielewski M., The effect of metal coatings on the interfacial bonding strength of ceramics to copper in sintered Cu-SiC composites, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2017.01.056, pp.1-9, 2017

Abstract:
Cu-SiC composites are very promising materials which have high thermal and electrical conductivity and may find many applications. Unfortunately, the main disadvantage of these materials is the dissolution of silicon in copper at elevated temperature, which significantly reduces their properties. In order to overcome this problem particles can be coated with a protective material before sintering. In this paper– the influence of three different metallic coatings on bonding strength were investigated. SiC particles were coated with tungsten, chromium or titanium. As reference a material with uncoated particles was prepared. The experiments were carried out with the use of microtensile tester. The highest increase in strength was observed in the case of chromium coating. On the other hand, the titanium coating, which was of very poor quality, decrease the bonding strength in comparison with uncoated particles. Furthermore, scanning electron and optical microscopes were used to determine the mechanism of debonding.

Keywords:
Interfacial bonding strength, Metal matrix composites, Tensile strength, Silicon carbide particles

4.Varga A., Ehrenreiter K., Aschenbrenner B., Kocieniewski P., Kochańczyk M., Lipniacki T., Baccarini M., RAF1/BRAF dimerization integrates the signal from RAS to ERK and ROKα, Science Signaling, ISSN: 1945-0877, DOI: 10.1126/scisignal.aai8482, Vol.10, No.469, pp.eaai8482-1-11, 2017
Varga A., Ehrenreiter K., Aschenbrenner B., Kocieniewski P., Kochańczyk M., Lipniacki T., Baccarini M., RAF1/BRAF dimerization integrates the signal from RAS to ERK and ROKα, Science Signaling, ISSN: 1945-0877, DOI: 10.1126/scisignal.aai8482, Vol.10, No.469, pp.eaai8482-1-11, 2017

Abstract:
Downstream of growth factor receptors and of the guanine triphosphatase (GTPase) RAS, heterodimers of the serine/threonine kinases BRAF and RAF1 are critical upstream kinases and activators of the mitogen-activated protein kinase (MAPK) module containing the mitogen-activated and extracellular signal–regulated kinase kinase (MEK) and their targets, the extracellular signal–regulated kinase (ERK) family. Either direct or scaffold protein–mediated interactions among the components of the ERK module (the MAPKKKs BRAF and RAF1, MEK, and ERK) facilitate signal transmission. RAF1 also has essential functions in the control of tumorigenesis and migration that are mediated through its interaction with the kinase ROKα, an effector of the GTPase RHO and regulator of cytoskeletal rearrangements. We combined mutational and kinetic analysis with mathematical modeling to show that the interaction of RAF1 with ROKα is coordinated with the role of RAF1 in the ERK pathway. We found that the phosphorylated form of RAF1 that interacted with and inhibited ROKα was generated during the interaction of RAF1 with the ERK module. This mechanism adds plasticity to the ERK pathway, enabling signal diversification at the level of both ERK and RAF. Furthermore, by connecting ERK activation with the regulation of ROKα and cytoskeletal rearrangements by RAF1, this mechanism has the potential to precisely coordinate the proper timing of proliferation with changes in cell shape, adhesion, or motility.

Keywords:
MAPK pathway, kinase RAF, protein isoform, phosphorylation, mathematical modeling

5.Banach Z., Larecki W., Entropy-based mixed three-moment description of fermionic radiation transport in slab and spherical geometries, Kinetic and Related Models, ISSN: 1937-5093, DOI: 10.3934/krm.2017035, Vol.10, No.4, pp.879-900, 2017
Banach Z., Larecki W., Entropy-based mixed three-moment description of fermionic radiation transport in slab and spherical geometries, Kinetic and Related Models, ISSN: 1937-5093, DOI: 10.3934/krm.2017035, Vol.10, No.4, pp.879-900, 2017

Abstract:
The mixed three-moment hydrodynamic description of fermionic radiation transport based on the Boltzmann entropy optimization procedure is considered for the case of one-dimensional flows. The conditions for realizability of the mixed three moments chosen as the energy density and two partial heat fluxes are established. The domain of admissible values of those moments is determined and the existence of the solution to the optimization problem is proved. Here, the standard approaches related to either the truncated Hausdorff or Markov moment problems do not apply because the non-negative fermionic distribution function, denoted f, must satisfy the inequality f _ 1 and, at the same time, there are three different intervals of integration in the integral formulae defining the mixed moments. The hydrodynamic equations are obtained in the form of the symmetric hyperbolic system for the Lagrange multipliers of the optimization problem with constraints. The potentials generating this system are explicitly determined as dilogarithm and trilogarithm functions of the Lagrange multipliers. The invertibility of the relation between moments and Lagrange multipliers is proved. However, the inverse relations cannot be determined in a closed analytic form. Using the H-theorem for the radiative transfer equation, it is shown that the derived system of hydrodynamic radiation equations has as a consequence an additional balance law with a non-negative source term.

Keywords:
Fermionic radiation, mixed moments, moment realizability domain, entropy optimization problem, symmetric hyperbolicity

6.Hoffman J., Chrzanowska J., Mościcki T., Radziejewska J., Stobinski L., Szymański Z., Plasma generated during underwater pulsed laser processing, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2017.01.185, pp.1-6, 2017
Hoffman J., Chrzanowska J., Mościcki T., Radziejewska J., Stobinski L., Szymański Z., Plasma generated during underwater pulsed laser processing, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2017.01.185, pp.1-6, 2017

Abstract:
The plasma induced during underwater pulsed laser ablation of graphite is studied both experimentally and theoretically. The results of the experiment show that the maximum plasma temperature of 25000 K is reached 20 ns from the beginning of the laser pulse and decreases to 6500 K after 1000 ns. The observed OH absorption band shows that the plasma plume is surrounded by the thin layer of dissociated water vapour at a temperature around 5500 K. The hydrodynamic model applied shows similar maximum plasma temperature at delay times between 14 ns and 30 ns. The calculations show also that already at 14th ns, the plasma electron density reaches 0.97·1027 m−3, which is the critical density for 1064 nm radiation. At the same time the plasma pressure is 2 GPa, which is consisted with earlier measurements of the peak pressure exerted on a target in similar conditions.

Keywords:
Underwater laser processing, Pulsed laser ablation in liquid, Laser induced plasma, Numerical modelling

7.Pakdel A., Witecka A., Rydzek G., Shri D.N.A., A comprehensive microstructural analysis of Al–WC micro- and nano-composites prepared by spark plasma sintering, MATERIALS AND DESIGN, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2017.01.064, Vol.119, pp.225-234, 2017
Pakdel A., Witecka A., Rydzek G., Shri D.N.A., A comprehensive microstructural analysis of Al–WC micro- and nano-composites prepared by spark plasma sintering, MATERIALS AND DESIGN, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2017.01.064, Vol.119, pp.225-234, 2017

Abstract:
There have been many investigations on metal matrix microcomposites produced by conventional casting routes; however, in the past decade, the focus has shifted more toward nanocomposites produced via solid state routes. To have a realistic view of performance prediction and optimum design of such composites, in this work Al matrix composites (AMCs) reinforced with WC microparticles, nanoparticles, and bimodal micro-/nano-particles were prepared by spark plasma sintering. The effects of particle size and concentration, and process variables (i.e. sintering temperature, duration, and pressure) on the evolution of microstructure, density and hardness of the composites were studied comprehensively. Full densification of AMCs with high particle concentration was problematic because of ceramic cluster formations in the microstructure. This effect was more emphasized in AMCs containing nanoparticles. AMCs with microparticles were more easily densified, but their hardness benefits were inferior. On the other hand, the mixture of micro- and nano-particles in Al-WC bimodal composites led to better matrix reinforcement integrity and an overall improvement in the microstructural properties. Finally, increasing the sintering temperature improved the microstructural features and hardness of the composites (more enhanced in high wt.% samples), but sintering duration and pressure did not have a big impact on the composite properties.

Keywords:
Composite, Nanoparticle, Microparticle, Powder metallurgy, SPS, Microstructure

8.Bajer C.I., Pisarski D., Szmidt T., Dyniewicz B., Intelligent damping layer under a plate subjected to a pair of masses moving in opposite directions, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.01.046, pp.1-15, 2017
Bajer C.I., Pisarski D., Szmidt T., Dyniewicz B., Intelligent damping layer under a plate subjected to a pair of masses moving in opposite directions, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.01.046, pp.1-15, 2017

Abstract:
Reducing displacements of a plate vibrating under a pair of masses traveling in opposite directions can be improved by adding a smart subsoil instead of a classical damping layer. We propose a material that acts according to the instantaneous state of the plate, i.e., its displacements and velocity. Such an intelligent damping layer reduces vertical displacements even by 40%–60%, depending on the type of load and the assumed objective function. Existing materials enable the application of the proposed layer in a semi-active mode. The passive mode can be applied with materials exhibiting direction-dependent viscosity.

Keywords:
Plate vibration, Moving load, Intelligent damping layer, Semi-active damping

9.Petryk H., Stupkiewicz S., Kucharski S., On direct estimation of hardening exponent in crystal plasticity from the spherical indentation test, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2016.09.025, pp.1-13, 2017
Petryk H., Stupkiewicz S., Kucharski S., On direct estimation of hardening exponent in crystal plasticity from the spherical indentation test, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2016.09.025, pp.1-13, 2017

Abstract:
A novel methodology is proposed for estimating the strain hardening exponent of a metal single crystal directly from the spherical indentation test, without the need of solving the relevant inverse problem. The attention is focused on anisotropic piling-up and sinking-in that occur simultaneously in different directions, in contrast to the standard case of axial symmetry for isotropic materials. To correlate surface topography parameters with the value of material hardening exponent, a finite-element study of spherical indentation has been performed within a selected penetration depth range using a finite-strain crystal plasticity model. It is shown how the power-law hardening exponent can be estimated from the measured pile-up/sink-in pattern around the residual impression after indentation in a (001)-oriented fcc single crystal of a small initial yield stress. For this purpose, a new parameter of surface topography is defined as the normalized material volume displaced around the nominal contact zone, calculated by integration of the local residual height (positive or negative) over a centered circular ring. That indicator can be easily determined from an experimental topography map available in a digital form. Comparison is made with the estimates based on measurements of the contact area and the slope of the load–penetration depth curve in logarithmic coordinates. The proposed methodology is extended to estimation of the hardening exponent simultaneously with the initial yield stress when the latter is not negligible. Experimental verification for a Cu single crystal leads to promising conclusions.

Keywords:
Metal crystal, Elastoplasticity, Finite deformation, Strain hardening, Experimental identification

10.Wójcik J., Lewandowski M., Żołek N., Grating Lobes Suppression by Adding Virtual Receiving Subaperture in Synthetic Aperture Imaging, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.013, Vol.76, pp.125-135, 2017
Wójcik J., Lewandowski M., Żołek N., Grating Lobes Suppression by Adding Virtual Receiving Subaperture in Synthetic Aperture Imaging, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.013, Vol.76, pp.125-135, 2017

Abstract:
A method of suppression of grating lobes is presented, analyzed, and verified. The method is based on creating a Virtual Receiving Subaperture (VRS) by adding virtual transducer elements not existing in the physical layout of the receiver. The VRS channels are filled with data based on signals from real channels. The analytical model of the synthetic aperture imaging system’s impulse response is presented to describe the properties of the VRS. The model shows a reduction of the receiving grating lobes’ amplitude (with a comparison to the main lobe’s amplitude) by a magnitude equal to the number of receiving transducer elements. It is shown that effective properties of the entire system with a VRS are similar to a system with a pitch in the receiving aperture that is twice as small. The numerical calculations of the impulse response show a doubling of the signal to noise ratio, which results in a reduction of the receiving grating lobes. For experimental validation, the generalized Plane Wave Imaging with and without the VRS is compared with a basic synthetic transmit aperture (STA) imaging. The experiment confirmed that the use of a VRS allows for visualizat ion of the objects in a medium in which they are not imaged without a VRS or are visualized with a lower contrast. The reduction of grating lobes attained using the proposed method is at the level of 15dB in the visualization of the superficial cyst.

Keywords:
Grating lobes, Image quality, Synthetic aperturę, Virtual subaperture

11.Michajłow M., Jankowski Ł., Szolc T., Konowrocki R., Semi-active reduction of vibrations in the mechanical system driven by an electric motor, OPTIMAL CONTROL APPLICATIONS & METHODS, ISSN: 0143-2087, DOI: 10.1002/oca.2297, pp.1-12, 2017
Michajłow M., Jankowski Ł., Szolc T., Konowrocki R., Semi-active reduction of vibrations in the mechanical system driven by an electric motor, OPTIMAL CONTROL APPLICATIONS & METHODS, ISSN: 0143-2087, DOI: 10.1002/oca.2297, pp.1-12, 2017

Abstract:
In this paper, a semi-active damping approach is used for reduction of vibrations in a laboratory drivetrain system. The considered drivetrain system is powered by an electric, asynchronous motor at the one side and loaded with a harmonically varying torque on the other side. Here, an influence of electromechanical interaction, i.e., an electromechanical coupling, between the electric motor and the mechanical system has been taken into consideration. The harmonic load signal induces torsional vibrations in the system, which in the steady-state phase of motion become periodic. The aim of the work is to determine the optimal control function for a semi-active damping element, leading to vibration reduction and considering only the steady-state phase of system motion. The optimal control is derived by using a semi-analytical approach based on the optimal control theory aided with supplementary numerical computations. The proposed methodology is fully general, and it can be directly applied to any type of a periodically oscillating system.

Keywords:
electric motor, electromechanical coupling, optimal control, periodic torsional vibrations, semi-active damping

12.Kujawska T., Secomski W., Byra M., Postema M., Nowicki A., Annular phased array transducer for preclinical testing of anti-cancer drug efficacy on small animals, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.008, Vol.76, pp.92-98, 2017
Kujawska T., Secomski W., Byra M., Postema M., Nowicki A., Annular phased array transducer for preclinical testing of anti-cancer drug efficacy on small animals, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.008, Vol.76, pp.92-98, 2017

Abstract:
A technique using pulsed High Intensity Focused Ultrasound (HIFU) to destroy deep-seated solid tumors is a promising noninvasive therapeutic approach. A main purpose of this study was to design and test a HIFU transducer suitable for preclinical studies of efficacy of tested, anti-cancer drugs, activated by HIFU beams, in the treatment of a variety of solid tumors implanted to various organs of small animals at the depth of the order of 1–2 cm under the skin. To allow focusing of the beam, generated by such transducer, within treated tissue at different depths, a spherical, 2-MHz, 29-mm diameter annular phased array transducer was designed and built. To prove its potential for preclinical studies on small animals, multiple thermal lesions were induced in a pork loin ex vivo by heating beams of the same: 6 W, or 12 W, or 18 W acoustic power and 25 mm, 30 mm, and 35 mm focal lengths. Time delay for each annulus was controlled electronically to provide beam focusing within tissue at the depths of 10 mm, 15 mm, and 20 mm. The exposure time required to induce local necrosis was determined at different depths using thermocouples. Location and extent of thermal lesions determined from numerical simulations were compared with those measured using ultrasound and magnetic resonance imaging techniques and verified by a digital caliper after cutting the tested tissue samples. Quantitative analysis of the results showed that the location and extent of necrotic lesions on the magnetic resonance images are consistent with those predicted numerically and measured by caliper. The edges of lesions were clearly outlined although on ultrasound images they were fuzzy. This allows to conclude that the use of the transducer designed offers an effective noninvasive tool not only to induce local necrotic lesions within treated tissue without damaging the surrounding tissue structures but also to test various chemotherapeutics activated by the HIFU beams in preclinical studies on small animals.

Keywords:
Spherical annular phased array transducer, Pulsed HIFU beam, Electronically adjustable focal length, Local tissue heating, Thermal ablation, Necrotic lesion

13.Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Lumelskyj D., Application of the Hertz formulation in the discrete element model of pressure-assisted sintering, GRANULAR MATTER, ISSN: 1434-5021, DOI: 10.1007/s10035-016-0699-9, Vol.19, No.1, pp.16-1-8, 2017
Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Lumelskyj D., Application of the Hertz formulation in the discrete element model of pressure-assisted sintering, GRANULAR MATTER, ISSN: 1434-5021, DOI: 10.1007/s10035-016-0699-9, Vol.19, No.1, pp.16-1-8, 2017

Abstract:
This paper presents the numerical modelling of initial powder compaction and pressure-assisted sintering performed by original viscoelastic discrete element model. The research is focused on the influence of the type of the model representing an elastic part of interparticle force. Two elastic contact models—linear and nonlinear Hertz model—have been implemented and used to analyse interaction of NiAl powder particles during compaction and sintering process. Numerical models have been validated using own experimental results. Microscopic effects (particle penetration) and macroscopic changes (relative density) have been compared. It has been shown that although both models represent properly macroscopic behaviour of the material at the sintering process, the Hertz model produces the results closer to the real experimental ones during the initial compaction stage. Evaluation of macroscopic quantities enables implementation of the discrete element model in the framework of the multiscale modelling framework which is currently developed for sintering processes.

Keywords:
Powder metallurgy, Sintering, Initial compaction, Elasticity, Discrete element method

14.Urbanek O., Sajkiewicz P., Pierini F., Czerkies M., Kołbuk D., Structure and properties of polycaprolactone/chitosan nonwovens tailored by solvent systems, Biomedical Materials, ISSN: 1748-6041, DOI: 10.1088/1748-605X/aa5647, Vol.12, No.1, pp.015020-1-12, 2017
Urbanek O., Sajkiewicz P., Pierini F., Czerkies M., Kołbuk D., Structure and properties of polycaprolactone/chitosan nonwovens tailored by solvent systems, Biomedical Materials, ISSN: 1748-6041, DOI: 10.1088/1748-605X/aa5647, Vol.12, No.1, pp.015020-1-12, 2017

Abstract:
Electrospinning of chitosan blends is a reasonable idea to prepare fibre mats for biomedical applications. Synthetic and natural components provide, for example, appropriate mechanical strength and biocompatibility, respectively. However, solvent characteristics and the polyelectrolyte nature of chitosan influence the spinnability of these blends. In order to compare the effect of solvent on polycaprolactone/chitosan fibres, two types of the most commonly used solvent systems were chosen, namely 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and acetic acid (AA)/formic acid (FA). Results obtained by various experimental methods clearly indicated the effect of the solvent system on the structure and properties of electrospun polycaprolactone/chitosan fibres. Viscosity measurements confirmed different polymer–solvent interactions. Various molecular interactions resulting in different macromolecular conformations of chitosan influenced its spinnability and properties. HFIP enabled fibres to be obtained whose average diameter was less than 250 nm while maintaining the brittle and hydrophilic character of the nonwoven, typical for the chitosan component. Spectroscopy studies revealed the formation of chitosan salts in the case of the AA/FA solvent system. Chitosan salts visibly influenced the structure and properties of the prepared fibre mats. The use of AA/FA caused a reduction of Young's modulus and wettability of the proposed blends. It was confirmed that wettability, mechanical properties and the antibacterial effect of polycaprolactone/chitosan fibres may be tailored by selecting an appropriate solvent system. The MTT cell proliferation assay revealed an increase of cytotoxicity to mouse fibroblasts in the case of 25% w/w of chitosan in electrospun nonwovens.

Keywords:
chitosan, electrospinning, PCL/chitosan fibres, solvent system, chitosan salts

15.Meissner M., Acoustics of small rectangular rooms: Analytical and numerical determination of reverberation parameters, APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2017.01.020, Vol.120, pp.111-119, 2017
Meissner M., Acoustics of small rectangular rooms: Analytical and numerical determination of reverberation parameters, APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2017.01.020, Vol.120, pp.111-119, 2017

Abstract:
A small rectangular room with hard walls has a number of acoustic flaws and the most serious drawback is a long reverberation time. A technique commonly used for improving room acoustics consists in increasing a sound absorption on a ceiling. In this study, the impact of acoustical treatment of a ceiling on reverberant properties of a small rectangular room was examined. Changes in the modal reverberation time due to this treatment were investigated by the analytical method. As was evidenced by calculations, the initial increase in a sound absorption on a ceiling causes a substantial decrease in the modal reverberation time and a treatment efficiency decreases with a further absorption increase. It was found also that for a room with hard walls statistical and wave theories give the same result as the modal reverberation time for oblique modes and the Sabine’s reverberation time are identical. A more detailed information about reverberant properties of a room was provided by the numerical method employing a backward integration of the squared room impulse response. Using this method, global and local reverberation parameters were determined. Numerical simulations discovered a quite good agreement between global and local reverberation time and high differences between global and local early decay time resulting from a nonlinear shape of a decay curve. Therefore, one can conclude that the global decay times characterize reasonably well a reverberation process in a late stage of sound decay but they are not correctly describe this process in an initial stage.

Keywords:
Small room acoustics, Modal expansion method, Room impulse response, Reverberation time, Early decay time

16.Golasiński K.M., Pieczyska E.A., Staszczak M., Maj M., Furuta T., Kuramoto S., Infrared thermography applied for experimental investigation of thermomechanical couplings in Gum Metal, Quantitative InfraRed Thermography Journal, ISSN: 1768-6733, DOI: 10.1080/17686733.2017.1284295, pp.1-8, 2017
Golasiński K.M., Pieczyska E.A., Staszczak M., Maj M., Furuta T., Kuramoto S., Infrared thermography applied for experimental investigation of thermomechanical couplings in Gum Metal, Quantitative InfraRed Thermography Journal, ISSN: 1768-6733, DOI: 10.1080/17686733.2017.1284295, pp.1-8, 2017

Abstract:
Results of initial investigation of thermomechanical couplings in innovative β-Ti alloy called Gum Metal subjected to tension are presented. The experimental set-up, consisting of testing machine and infrared camera, enabled to obtain stress–strain curves with high accuracy and correlate them to estimated temperature changes of the specimen during the deformation process. Both ultra-low elastic modulus and high strength of Gum Metal were confirmed. The infrared measurements determined average and maximal temperature changes accompanying the alloy deformation process, allowed to estimate thermoelastic effect, which is related to the alloy yield point. The temperature distributions on the specimen surface served to analyse strain localization effects leading to the necking and rupture.

Keywords:
Gum Metal, thermomechanical coupling, nonlinear elasticity, yield point, infrared camera

17.Ignaczak J., Domański W., An asymptotic approach to one-dimensional model of nonlinear thermoelasticity at low temperatures and small strains, JOURNAL OF THERMAL STRESSES, ISSN: 0149-5739, DOI: 10.1080/01495739.2016.1276872, pp.1-10, 2017
Ignaczak J., Domański W., An asymptotic approach to one-dimensional model of nonlinear thermoelasticity at low temperatures and small strains, JOURNAL OF THERMAL STRESSES, ISSN: 0149-5739, DOI: 10.1080/01495739.2016.1276872, pp.1-10, 2017

Abstract:
A one-dimensional nonlinear homogeneous isotropic thermoelastic model with an elastic heat flow at low temperatures and small strains is analyzed using the method of weakly nonlinear asymptotics. For such a model, both the free energy and the heat flux vector depend not only on the absolute temperature and strain tensor but also on an elastic heat flow that satisfies an evolution equation. The governing equations are reduced to a matrix partial differential equations, and the associated Cauchy problem with a weakly perturbed initial condition is solved. The solution is given in the form of a power series with respect to a small parameter, the coefficients of which are functions of a slow variable that satisfy a system of nonlinear second-order ordinary differential transport equations. A family of closed-form solutions to the transport equations is obtained. For a particular Cauchy problem in which the initial data are generated by a closed-form solution to the transport equations, the asymptotic solution in the form of a sum of four traveling thermoelastic waves admitting blow-up amplitudes is presented.

Keywords:
Low temperatures, nonlinear thermoelasticity, small strains, weakly nonlinear asymptotics

18.Chwojnowski A., Kruk A., Wojciechowski C., Łukowska E., Dulnik J., Sajkiewicz P., The dependence of the membrane structure on the non-woven forming the macropores in the 3D scaffolds preparation, Desalination and Water Treatment, ISSN: 1944-3994, DOI: 10.5004/dwt.2017.11394, Vol.64, pp.324-331, 2017
Chwojnowski A., Kruk A., Wojciechowski C., Łukowska E., Dulnik J., Sajkiewicz P., The dependence of the membrane structure on the non-woven forming the macropores in the 3D scaffolds preparation, Desalination and Water Treatment, ISSN: 1944-3994, DOI: 10.5004/dwt.2017.11394, Vol.64, pp.324-331, 2017

Abstract:
Three types of membrane structures with wide pores were compared in this study. One of the membranes was obtained from polyethersulfone using cellulose fibers as the macropore precursors. Two of the fibers were obtained from poly(L-lactide). As the macropore precursors olyvinylpyrrolidone (1.2 MDa) and pork gelatin non-woven were used, the influence of non-woven fibers on the structure of membranes was shown. Necessity of specific membrane structure application was explained. The hoice of polymers and co-polymers with a range of biodegradation times can determine the scaffold type suitable for the age of a patient.

Keywords:
Polysulfone membrane, Polyester membranes, Membrane structures, Biodegradable membranes, 3D scaffold

19.Kruka A., Gadomska-Gajadhur A., Ruśkowski P., Chwojnowski A., Dulnik J., Synoradzki L., Preparation of biodegradable semi-permeable membranes as 3D scaffolds for cell cultures, Desalination and Water Treatment, ISSN: 1944-3994, DOI: 10.5004/dwt.2017.11415, Vol.64, pp.317-323, 2017
Kruka A., Gadomska-Gajadhur A., Ruśkowski P., Chwojnowski A., Dulnik J., Synoradzki L., Preparation of biodegradable semi-permeable membranes as 3D scaffolds for cell cultures, Desalination and Water Treatment, ISSN: 1944-3994, DOI: 10.5004/dwt.2017.11415, Vol.64, pp.317-323, 2017

Abstract:
Results of the preparation of semi-permeable membranes made of biodegradable polymers membranes were presented. Among known polyesters, polylactide was selected for research. The membranes were obtained using wet phase inversion method. The influence of polyvinylpyrrolidone and polymeric nano-non-wovens as pores precursors on the structure of obtained membranes was analysed. It was shown, that utilisation of polymeric nano-non-wovens enabled preparation of semi-permeable membranes, which could be used as wide-pore 3D-type cellular scaffolds.

Keywords:
Biodegradable polymers membranes, Biodegradable polyesters, Porous three-dimensional scaffolds, Inversion phase method

20.Błachowski B., An Y., Spencer Jr. B.F., Ou J., Axial strain accelerations approach for damage localization in statically determinate truss structures, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1467-8667, DOI: 10.1111/mice.12258, pp.1-15, 2017
Błachowski B., An Y., Spencer Jr. B.F., Ou J., Axial strain accelerations approach for damage localization in statically determinate truss structures, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1467-8667, DOI: 10.1111/mice.12258, pp.1-15, 2017

Abstract:
This work proposes an efficient and reliable method for damage localization in truss structures. The damage is localized on the basis of measured acceleration signals of the structure followed by simple statistical signal processing. It has three main advantages over many existing methods. Firstly, it can be directly applied to real engineering structures without the need of identifying modal parameters or solving any global optimization problem. Secondly, the proposed method has higher sensitivity to damage than some other frequently used methods and allows to localize damage as small as a few percents. Thirdly, it is a model-free method, which does not require precise finite element model development or updating. Validation of the method has been conducted on numerical examples and laboratory-scale trusses. Two types of frequently used trusses have been selected for this study, namely Howe and Bailey trusses. The presented experimental validation of the method shows its efficiency and robustness for damage localization in truss structures.

21.Konowrocki R., An Electricity Consumption of a Train Drive System Used in a High Speed Train Caused by Change of Mechanical Parameters of this Drive, III Konferencja Naukowa „Szkoła Logistyki” , 2017-01-10/01-13, Wisła (PL), pp.1-1, 2017
Konowrocki R., An Electricity Consumption of a Train Drive System Used in a High Speed Train Caused by Change of Mechanical Parameters of this Drive, III Konferencja Naukowa „Szkoła Logistyki” , 2017-01-10/01-13, Wisła (PL), pp.1-1, 2017

Abstract:
The cost of maintenance, the reliability and the safety of railway operation depend strongly on the quality of the wheelsets and driving systems. Deformations and mechanical vibrations are phenomena associated with a functioning of majority of railway vehicle drivetrain structures. The time dependent variation of the contact forces between the wheels and the rails is highest importance, as sources of a torsion vibration in the systems. The knowledge about torsional vibrations in drive transmission systems of railway vehicles is of a great importance in the fields dynamics and fatigue of the mechanical systems. An electromechanical model of the railway vehicle drive system has been presented in the work. The values of electrical parameter characterizing the driving motor obtained from electric motor model have been used for determine the amounts of electric energy consumed by self-excited torsional vibration in the wheelset drivetrain system.

Keywords:
electric motor, cost of maintenance, electromechanical model, torsion vibration

22.Konowrocki R., Kukulski J., Walczak S., Costs Operating of Railway Braking Systems Due to the Influence of Hot Spots on the Brake Discs, III Konferencja Naukowa „Szkoła Logistyki” , 2017-01-10/01-13, Wisła (PL), pp.1, 2017
Konowrocki R., Kukulski J., Walczak S., Costs Operating of Railway Braking Systems Due to the Influence of Hot Spots on the Brake Discs, III Konferencja Naukowa „Szkoła Logistyki” , 2017-01-10/01-13, Wisła (PL), pp.1, 2017

Abstract:
In the paper presents experimental studies the influence of the formation of the hot spots on a brake disc. The heat produced in the brake system often leads to the appearance of hot spots on the surfaces of friction pairs during rapid braking. Nature and extent of the intensity of the phenomenon depends greatly on the mechanical and thermal properties of these friction pair materials. The temperature distribution in the elements analyzed systems friction affects their thermal deformation, initiating the above phenomenon. Shown in the work of the results of tests and analyzes the formation of the hot bands and the hot spots on the brake discs used in high-speed railway vehicles, provided information on the temperature distribution on the surface.
One of the consequences of such a process is the increased wear and reduce the coefficient of friction. Measurements of the hardness of the hot bands and surface roughness of brake discs showed the effects of such phenomena on the change on the structure of the cast iron and steel discs materials. An increase the hardness of this hot area on the discs surface of may result in increased maintenance costs. The costs caused by for a more frequent lathing of the brake discs can occur. These changes also influences to reduce the coefficient of friction in the friction pair.

Keywords:
hotspot, maintenance costs, friction, infrared thermography, thermal coupling

23.Ustrzycka A., Kowalewski Z.L., Modelling of fatigue damage mechanisms supported by full-field optical methods, PLASTICITY 2017, INTERNATIONAL CONFERENCE ON PLASTICITY, DAMAGE, AND FRACTURE 2017, 2017-01-03/01-09, Puerto Vallarta (MX), pp.91-93, 2017
Ustrzycka A., Kowalewski Z.L., Modelling of fatigue damage mechanisms supported by full-field optical methods, PLASTICITY 2017, INTERNATIONAL CONFERENCE ON PLASTICITY, DAMAGE, AND FRACTURE 2017, 2017-01-03/01-09, Puerto Vallarta (MX), pp.91-93, 2017

Abstract:
The aim of this work consists a development of the Gurson-Tvergaard-Needleman model (GNT) of damage evolution in elastic-plastic materials. This model is supported by optical method of stress and strain monitoring (ESPI) for early detection, localization and monitoring of damage in materials under fatigue loading.

24.Průša V., Řehoř M., Tůma K., Colombeau algebra as a mathematical tool for investigating step load and step deformation of systems of nonlinear springs and dashpots, ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND PHYSIK, ISSN: 0044-2275, DOI: 10.1007/s00033-017-0768-x, Vol.68, No.24, pp.1-13, 2017
Průša V., Řehoř M., Tůma K., Colombeau algebra as a mathematical tool for investigating step load and step deformation of systems of nonlinear springs and dashpots, ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND PHYSIK, ISSN: 0044-2275, DOI: 10.1007/s00033-017-0768-x, Vol.68, No.24, pp.1-13, 2017

Abstract:
The response of mechanical systems composed of springs and dashpots to a step input is of eminent interest in the applications. If the system is formed by linear elements, then its response is governed by a system of linear ordinary differential equations. In the linear case, the mathematical method of choice for the analysis of the response is the classical theory of distributions. However, if the system contains nonlinear elements, then the classical theory of distributions is of no use, since it is strictly limited to the linear setting. Consequently, a question arises whether it is even possible or reasonable to study the response of nonlinear systems to step inputs. The answer is positive. A mathematical theory that can handle the challenge is the so-called Colombeau algebra. Building on the abstract result by Průša and Rajagopal (Int J Non-Linear Mech 81:207–221, 2016), we show how to use the theory in the analysis of response of nonlinear spring–dashpot and spring–dashpot–mass systems.

Keywords:
Mechanical systems, Nonlinear ordinary differential equations, Jump discontinuities, Colombeau algebra

25.Stapelmann K., Fiebrand M., Raguse M., Lackmann J.W., Postema M., Moeller R., Awakowicz P., A combined low-pressure hydrogen peroxide evaporation plus hydrogen plasma treatment method for sterilization – Part 1: Characterization of the condensation process and proof-of-concept, Plasma Process Polymers, ISSN: 1612-8869, DOI: 10.1002/ppap.201600198, Vol.14, pp.1-10, 2017
Stapelmann K., Fiebrand M., Raguse M., Lackmann J.W., Postema M., Moeller R., Awakowicz P., A combined low-pressure hydrogen peroxide evaporation plus hydrogen plasma treatment method for sterilization – Part 1: Characterization of the condensation process and proof-of-concept, Plasma Process Polymers, ISSN: 1612-8869, DOI: 10.1002/ppap.201600198, Vol.14, pp.1-10, 2017

Abstract:
A combined hydrogen peroxide evaporation and hydrogen low-pressure plasma treatment process for sterilization is introduced and investigated. The combination of hydrogen peroxide evaporation followed by hydrogen plasma treatment offers an advantage regarding sterilization in complex metal geometries or in sealed sterile bags, where plasma treatment alone faces challenges. Within this contribution, the droplet size and film homogeneity after condensation is investigated by optical diagnostics. Sterilization tests with common challenge organisms show the sterilization capabilities of the combined proces in a process challenge device mimicking the worst-casescenario for plasma treatment in a small metal box. Furthermore, sterilization in sealed sterile bags clearly demonstrates the advantage of the combined process, showing full spore inactivation solely for the combined process

Keywords:
bacterial spores, capacitively coupled, low-pressure discharges, sterilization

26.Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Response discontinuities in the solution of the incremental Mori–Tanaka scheme for elasto-plastic composites, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.69, No.1, pp.3-27, 2017
Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Response discontinuities in the solution of the incremental Mori–Tanaka scheme for elasto-plastic composites, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.69, No.1, pp.3-27, 2017

Abstract:
The incremental Mori–Tanaka model of elasto-plastic composites is discussed, and the corresponding finite-step formulation is shown to lead to discontinuities in the overall response at the instant of elastic-to-plastic transition in the matrix. Specifically, two situations may be encountered: the incremental equations may have two solutions or no solution. In the former situation, switching between the two solutions is associated with a jump in the overall stress. Response discontinuities are studied in detail for a special case of proportional deviatoric loading. The discontinuities constitute an undesirable feature of the incremental Mori–Tanaka scheme that apparently has not been discussed in the literature so far. Remedies to the related problems are briefly discussed.

Keywords:
mean-field homogenization, Mori–Tanaka method, incremental scheme, composite materials, elasto-plasticity

27.Johansen K., Kimmel E., Postema M., Theory of Red Blood Cell Oscillations in an Ultrasound Field, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2017-0013, Vol.42, No.1, pp.121-126, 2017
Johansen K., Kimmel E., Postema M., Theory of Red Blood Cell Oscillations in an Ultrasound Field, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2017-0013, Vol.42, No.1, pp.121-126, 2017

Abstract:
Manipulating particles in the blood pool with noninvasive methods has been of great interest in therapeutic delivery. Recently, it was demonstrated experimentally that red blood cells can be forced to translate and accumulate in an ultrasound field. This acoustic response of the red blood cells has been attributed to sonophores, gas pockets that are formed under the influence of a sound field in the inner-membrane leaflets of biological cells. In this paper, we propose a simpler model: that of the compressible membrane. We derive the spatio-temporal cel dynamics for a spherically symmetric single cell, whilst regarding the cell bilayer membrane as two monolayer Newtonian viscous liquids, separated by a thin gas void.
When applying the newly-derived equations to a red blood cell, it is observed that the void inside the bilayer expands to multiples of its original thickness, even at clinically safe acoustic pressure amplitudes. For causing permanent cell rupture during expansion, however, the acoustic pressure amplitudes needed would have to surpass the inertial cavitation threshold by a factor 10. Given the incompressibility of the inner monolayer, the radial oscillations of a cell are governed by the same set of equations as those of a forced antibubble. Evidently, these equations must hold for liposomes under sonication, as well.

Keywords:
Spatio-temporal cell dynamics, Rayleigh-Plesset equation, spherical cell, red blood cell, erythrocyte

28.Labra C., Rojek J., Oñate E., Discrete/Finite Element Modelling of Rock Cutting with a TBM Disc Cutter, Rock Mechanics and Rock Engineering, ISSN: 0723-2632, DOI: 10.1007/s00603-016-1133-7, Vol.50, pp.621-635, 2017
Labra C., Rojek J., Oñate E., Discrete/Finite Element Modelling of Rock Cutting with a TBM Disc Cutter, Rock Mechanics and Rock Engineering, ISSN: 0723-2632, DOI: 10.1007/s00603-016-1133-7, Vol.50, pp.621-635, 2017

Abstract:
This paper presents advanced computer simulation of rock cutting process typical for excavation works in civil engineering. Theoretical formulation of the hybrid discrete/finite element model has been presented. The discrete and finite element methods have been used in different subdomains of a rock sample according to expected material behaviour, the part which is fractured and damaged during cutting is discretized with the discrete elements while the other part is treated as a continuous body and it is modelled using the finite element method. In this way, an optimum model is created, enabling a proper representation of the physical phenomena during cutting and efficient numerical computation. The model has been applied to simulation of the laboratory test of rock cutting with a single TBM (tunnel boring machine) disc cutter. The micromechanical parameters have been determined using the dimensionless relationships between micro- and macroscopic parameters. A number of numerical simulations of the LCM test in the unrelieved and relieved cutting modes have been performed. Numerical results have been compared with available data from in-situ measurements in a real TBM as well as with the theoretical predictions showing quite a good agreement. The numerical model has provided a new insight into the cutting mechanism enabling us to investigate the stress and pressure distribution at the tool–rock interaction. Sensitivity analysis of rock cutting performed for different parameters including disc geometry, cutting velocity, disc penetration and spacing has shown that the presented numerical model is a suitable tool for the design and optimization of rock cutting process.

Keywords:
Rock cutting, Disc cutters, TBM, Numerical model, Discrete/finite element method, Simulation

29.Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Lumelskyj D., Modeling of a Sintering Process at Various Scales, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2017.02.210, Vol.177, pp.263-270, 2017
Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Lumelskyj D., Modeling of a Sintering Process at Various Scales, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2017.02.210, Vol.177, pp.263-270, 2017

Abstract:
This paper presents modeling of a sintering process at various scales. Sintering is a powder metallurgy process consisting in consolidation of powder materials at elevated temperature but below the melting point. Sintering models at the atomistic, microscopic and macroscopic scales have been presented. Sintering is a process governed by diffusion therefore the atomistic modeling using the molecular dynamics has been focused on investigation of the diffusion process. The micromechanical model has been developed within the framework of the discrete element method. It allows us to consider microstructure and its changes during sintering. The macroscopic model is based on the continuum phenomenological approach. It combines elastic, thermal and viscous creep deformation. The methodology to determine macroscopic quantities: stress, strains and constitutive viscous properties from the discrete element simulations has been presented. Possibilities of the developed models have been demonstrated by applying them to simulation of sintering of the intermetallic NiAl powder. Own experimental results have been used to calibrate and validate numerical models.

Keywords:
sintering, modeling, discrete element method, diffusion, molecular dynamics, macroscopic model

30.Jarząbek D.M., Gwiazda M., Dera W., The Influence of Alkali Metal Chloride Treatments on the Wear Resistance of Silicon Surfaces for Possible Use in MEMS, TRIBOLOGY TRANSACTIONS, ISSN: 1040-2004, DOI: 10.1080/10402004.2017.1296211, pp.1-7, 2017
Jarząbek D.M., Gwiazda M., Dera W., The Influence of Alkali Metal Chloride Treatments on the Wear Resistance of Silicon Surfaces for Possible Use in MEMS, TRIBOLOGY TRANSACTIONS, ISSN: 1040-2004, DOI: 10.1080/10402004.2017.1296211, pp.1-7, 2017

Abstract:
The wear of contacting silicon surfaces in microelectromechanical systems (MEMS) has been a longstanding concern. To address this issue, the effects of immersing silicon surfaces into alkali metal chloride solutions (LiCl, NaCl, CsCl) on their sliding friction and wear were investigated. A custom-built reciprocating tribometer was used with a sapphire ball as the counterbody. Results indicated that the friction coefficient between the silicon surface (p-doped, orientation (100)) and a sapphire ball can be reduced by up to 30% by treating the silicon surfaces in aqueous salt solutions (concentration 1 mol/L, exposure for 24 h). These modified surfaces also have higher wear resistance and a significant change in wettability. After immersion, the contact angle between the silicon surface and water was reduced by approximately 50%. These results may lead to new, simple, and inexpensive methods to increase the wear resistance of silicon surfaces for use in MEMs devices.

Keywords:
silicon surface, wear, friction, alkali metal chlorides

31.Kijewska M., Kocyk M., Kloss M., Stępniak K., Korwek Z., Polakowska R., Dąbrowski M., Gieryng A., Wojtas B., Ciechomska I.A., Kamińska B., The embryonic type of SPP1 transcriptional regulation is re-activated in glioblastoma, Oncotarget, ISSN: 1949-2553, DOI: 10.18632/oncotarget.14092, pp.1-16, 2016
Kijewska M., Kocyk M., Kloss M., Stępniak K., Korwek Z., Polakowska R., Dąbrowski M., Gieryng A., Wojtas B., Ciechomska I.A., Kamińska B., The embryonic type of SPP1 transcriptional regulation is re-activated in glioblastoma, Oncotarget, ISSN: 1949-2553, DOI: 10.18632/oncotarget.14092, pp.1-16, 2016

Abstract:
Osteopontin (SPP1, a secreted phosphoprotein 1) is primarily involved in immune responses, tissue remodelling and biomineralization. However, it is also overexpressed in many cancers and regulates tumour progression by increasing migration, invasion and cancer stem cell self-renewal. Mechanisms of SPP1 overexpression in gliomas are poorly understood. We demonstrate overexpression of two out of five SPP1 isoforms in glioblastoma (GBM) and differential isoform expression in glioma cell lines. Up-regulated SPP1 expression is associated with binding of the GLI1 transcription factor to the promoter and OCT4 (octamer-binding transcription factor 4) to the first SPP1 intron of the SPP1 gene in human glioma cells but not in non-transformed astrocytes. GLI1 knockdown reduced SPP1 mRNA and protein levels in glioma cells. GLI1 and OCT4 are known regulators of stem cell pluripotency. GBMs contain rare cells that express stem cell markers and display ability to self-renew. We reveal that SPP1 is overexpressed in glioma initiating cells defined by high rhodamine 123 efflux, sphere forming capacity and stemness marker expression. Forced differentiation of human glioma spheres reduced SPP1 expression. Knockdown of SPP1, GLI1 or CD44 with siRNAs diminished sphere formation. C6 glioma cells stably depleted of Spp1 displayed reduced sphere forming capacity and downregulated stemness marker expression. Overexpression of the wild type Spp1, but not Spp1 lacking a Cd44 binding domain, rescued cell ability to form spheres. Our findings show re-activation of the embryonic-type transcriptional regulation of SPP1 in malignant gliomas and point to the importance of SPP1-CD44 interactions in self-renewal and pluripotency glioma initiating cells.

Keywords:
osteopontin, glioma initiating cells, transcription factors, stemness factors, self-renewal

32.Winnicki M., Małachowska A., Baszczuk A., Rutkowska-Gorczyca M., Kukla D., Lachowicz M., Ambroziak A., Corrosion protection and electrical conductivity of copper coatings deposited by low-pressure cold spraying, SURFACE AND COATINGS TECHNOLOGY, ISSN: 0257-8972, DOI: 10.1016/j.surfcoat.2016.12.101, pp.1-19, 2016
Winnicki M., Małachowska A., Baszczuk A., Rutkowska-Gorczyca M., Kukla D., Lachowicz M., Ambroziak A., Corrosion protection and electrical conductivity of copper coatings deposited by low-pressure cold spraying, SURFACE AND COATINGS TECHNOLOGY, ISSN: 0257-8972, DOI: 10.1016/j.surfcoat.2016.12.101, pp.1-19, 2016

Abstract:
Aluminium/copper contacts occur in power networks made of aluminium alloy busbars. Bolted joints of aluminium and copper cause galvanic corrosion of aluminium in the presence of electrolyte. The paper focuses on the effect of different powder morphology and the addition of ceramics on coating porosity and consequently on corrosion resistance and electrical conductivity behaviour. In this work, corrosion protection of copper coatings deposited by low-pressure cold spraying (LPCS) onto AA 1350 aluminium alloy is examined. The coatings were sprayed using two copper powders of different morphology, namely spherical and dendritic ones. These powders were mixed with alumina before spraying in a 50:50 weight ratio and composite coatings were deposited. The coating microstructures were characterized by the scanning electron microscopy (SEM). The measurements of coating hardness in the middle of the coating thickness were carried out. The coating corrosion protection was analysed by polarization measurements. All coatings showed increased corrosion potential as compared to the substrate. The electrical conductivity of coatings was determined by eddy-current measurements and showed coating conductivity up to 63% IACS. Moreover, coatings heat treatment was conducted to further increase electrical conductivity.

Keywords:
cold spray, corrosion resistance, polarization measurements, electrical conductivity

33.Zawidzki M., Optimization of Multi-branch Truss-Z based on Evolution Strategy, Advances in Engineering Software, ISSN: 0965-9978, DOI: 10.1016/j.advengsoft.2016.07.015, Vol.100, pp.113-125, 2016
Zawidzki M., Optimization of Multi-branch Truss-Z based on Evolution Strategy, Advances in Engineering Software, ISSN: 0965-9978, DOI: 10.1016/j.advengsoft.2016.07.015, Vol.100, pp.113-125, 2016

Abstract:
This paper concerns multi-branch Truss-Z networks (MTZ). A possible scenario for creating a “multi-branch bridge” linking 6 terminals of pedestrian and cycling communication is presented. This process is formulated as a constrained minimization problem. New, biology-inspired nomenclature for MTZ and encoding for MTZ are introduced. Several operations for MTZs are introduced and illustrated. The functionality of these operations is illustrated with transformation from a random MTZ to a “proper” 6-branch MTZ network. A population-based heuristic experiment is presented to demonstrate that the introduced operators allow us to create any desirable MTZ. A cost function for the considered scenario is introduced. The genetic operations are interpreted and visualized. A number of feasible MTZ layouts produced by an evolution strategy-based algorithm are presented. One of these layouts is used for creation of the spatial 6-terminal MTZ, which is also visualized.

Keywords:
Extremely modular system, Modular ramp system, Multi-branch network, Modular structure encoding, Evolution strategy, Discrete layout optimization

34.Basista M., Węglewski W., Bochenek K., Poniżnik Z., Nowak Z., Micro-CT Finite Element Analysis of Thermal Residual Stresses and Fracture in Metal-Ceramic Composites, Advanced Engineering Materials, ISSN: 1438-1656, DOI: 10.1002/adem.201600725, pp.1-9, 2016
Basista M., Węglewski W., Bochenek K., Poniżnik Z., Nowak Z., Micro-CT Finite Element Analysis of Thermal Residual Stresses and Fracture in Metal-Ceramic Composites, Advanced Engineering Materials, ISSN: 1438-1656, DOI: 10.1002/adem.201600725, pp.1-9, 2016

Abstract:
This paper presents a simple way of using X-ray micro-computed tomography (micro-CT) in numerical modeling of material properties of metal-ceramic composites. It shows step by step the proposed methodology with details of the finite element mesh creation, so that it can easily be reproduced by interested researchers. Two case studies are considered to show the proposed approach at work: i) determination of processing-induced residual stresses in hot pressed Cr/Al2O3 and NiAl/Al2O3 particulate composites and ii) determination of J-integral for an interpenetrating phase composite made of porous alumina preform infiltrated with molten copper. The method is straightforward and effective but has its limitations that are pointed out.

35.Sulejczak D., Taraszewska A., Chrapusta S.J., Dziewulska D., Nakielski P., Rafałowska J., Nanofiber mat spinal cord dressing-released glutamate impairs blood-spinal cord barrier, FOLIA NEUROPATHOLOGICA, ISSN: 1641-4640, DOI: 10.5114/fn.2016.64818, Vol.54, No.4, pp.392-404, 2016
Sulejczak D., Taraszewska A., Chrapusta S.J., Dziewulska D., Nakielski P., Rafałowska J., Nanofiber mat spinal cord dressing-released glutamate impairs blood-spinal cord barrier, FOLIA NEUROPATHOLOGICA, ISSN: 1641-4640, DOI: 10.5114/fn.2016.64818, Vol.54, No.4, pp.392-404, 2016

Abstract:
An excessive glutamate level can result in excitotoxic damage and death of central nervous system (CNS) cells, and is involved in the pathogenesis of many CNS diseases. It may also be related to a failure of the blood-spinal cord barrier (BSCB). This study was aimed at examining the effects of extended administration of monosodium glutamate on the BSCB and spinal cord cells in adult male Wistar rats. The glutamate was delivered by subarachnoidal application of glutamate-carrying electrospun nanofiber mat dressing at the lumbar enlargement level. Half of the rats with the glutamate-loaded mat application were treated systemically with the histone deacetylase inhibitor valproic acid. A group of intact rats and a rat group with subarachnoidal application of an ‘empty’ (i.e., carrying no glutamate) nanofiber mat dressing served as controls. All the rats were euthanized three weeks later and lumbar fragments of their spinal cords were harvested for histological, immunohistochemical and ultrastructural studies. The samples from controls revealed normal parenchyma and BSCB morphology, whereas those from rats with the glutamate-loaded nanofiber mat dressing showed many intraparenchymal microhemorrhages of variable sizes. The capillaries in the vicinity of the glutamate-carrying dressing (in the meninges and white matter alike) were edematous and leaky, and their endothelial cells showed degenerative changes: extensive swelling, enhanced vacuo­lization and the presence of vascular intraluminal projections. However, endothelial tight junctions were generally well preserved. Some endothelial cells were dying by necrosis or apoptosis. The adjacent parenchyma showed astrogliosis with astrocytic hypertrophy and swelling of perivascular astrocytic feet. Neurons in the parenchyma revealed multiple symptoms of degeneration, including, inter alia, perikaryal, dendritic and axonal swelling, and destruction of organelles. All the damage symptoms were slightly less severe in the rats given valproic acid treatment, and were absent from both the intact rats and the rats with ‘empty’ nanofiber mat dressing. These results demonstrate that glutamate-loaded nanofiber mat dressing can locally create glutamate levels capable of damaging BSCB and that the resulting damage can be mitigated with concurrent systemic valproate treatment.

Keywords:
astrocyte, blood-spinal cord barrier, CNS damage, degeneration, endothelium, excitotoxicity, glutamate, neuron, valproate, vessels

36.Brandt A.M., O wpływie promieniowania jonizującego na beton, przegląd stanu wiedzy, CEMENT, WAPNO, BETON, ISSN: 1425-8129, Vol.6, pp.423-438, 2016
Brandt A.M., O wpływie promieniowania jonizującego na beton, przegląd stanu wiedzy, CEMENT, WAPNO, BETON, ISSN: 1425-8129, Vol.6, pp.423-438, 2016

Abstract:
Zagadnienie wpływu promieniowania jonizującego na osłony betonowe było rozpatrywane już przez badaczy parędziesiąt lat temu, na przykład Hilsdorf i in. w 1978 r., co jednak wobec przewidywanej wówczas eksploatacji reaktorów przez 30-40 lat mogło nie mieć istotnego znaczenia. Obecnie działające i budowane elektrownie jądrowe będą zapewne działać przez 60-80 lat, więc wpływ promieniowania na mikrostrukturę i właściwości betonu w osłonach wymaga starannego zbadania. Prace takie podjęte w okresie ostatnich dziesięciu lat w laboratoriach w USA, Japonii i innych krajów wskazują na niebezpieczeństwo degradacji betonu po przyjęciu określonej dawki promieniowania, a zmiany mikrostruktury i pęcznienie betonu mogą w znacznym stopniu zmniejszyć szczelność i wytrzymałość osłon w okresie przewidzianej eksploatacji reaktorów. Podobne zjawisko może dotyczyć, choć po dłuższym okresie, także składowisk odpadów radioaktywnych. W artykule przedstawione obecną wiedzę w tej tematyce oraz zagadnienia wymagające nadal intensywnych badań.

37.Wasilewski M., Pisarski D., Bajer C.I., Adaptive stabilization of partially damaged vibrating structures, Machine Dynamics Research, ISSN: 2080-9948, Vol.40, No.1, pp.65-82, 2016
Wasilewski M., Pisarski D., Bajer C.I., Adaptive stabilization of partially damaged vibrating structures, Machine Dynamics Research, ISSN: 2080-9948, Vol.40, No.1, pp.65-82, 2016

Abstract:
In this paper, an online adaptive continuous-time control algorithm will be studied in the vibration control problem. The examined algorithm is a Reinforcement Learning based scheme able to adapt to the changing system’s dynamics and providing control converging to the optimal control. Firstly, a brief description of the algorithm is provided. Then, the algorithm is studied by the numeric simulation. The controlled model is a simple conjugate oscillator with a sudden change of its rigidity. The effectiveness of the adaptation of the algorithm is compared to the simulation results of controlling the same object by the traditional Linear Quadratic Regulator. Because of the lack of constraints for a system size or its linearity, this algorithm is suitable for optimal stabilization of more complex vibrating structures.

Keywords:
Vibration control, Adaptive control, Optimal control, Policy iterations, Hamilton-Jacobi-Bellman equation

38.Kuś W., Mrozek A., Burczyński T., Memetic Optimization of Graphene-Like Materials on Intel PHI Coprocessor, Lecture Notes in Artificial Intelligence, ISSN: 0302-9743, DOI: 10.1007/978-3-319-39378-0_35, Vol.9692, pp.401-410, 2016
Kuś W., Mrozek A., Burczyński T., Memetic Optimization of Graphene-Like Materials on Intel PHI Coprocessor, Lecture Notes in Artificial Intelligence, ISSN: 0302-9743, DOI: 10.1007/978-3-319-39378-0_35, Vol.9692, pp.401-410, 2016

Abstract:
The paper is devoted to the optimization of energy of carbon based atomic structure with use of the memetic algorithm. The graphene like atoms structure is coded into floating point genes and underwent evolutionary changes. The global optimization algorithm is supported by local gradient based improvement of chromosomes. The optimization problem is solved with the use of Intel PHI (Intel Many Integrated Core Architecture – Intel MIC). The example of optimization and speedup measurement for parallel optimization are given in the paper.

Keywords:
Parallel computing, Intel PHI, Optimization, Graphene-like materials

39.Burczyński T., Mrozek A., Kuś W., Computational models of new graphene-like nano-structures, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P253, pp.1-2, 2016
Burczyński T., Mrozek A., Kuś W., Computational models of new graphene-like nano-structures, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P253, pp.1-2, 2016

Keywords:
carbon nano-structures, conjugated gradient method, evolutionary algorithm

40.Burczyński T., Mrozek A., Kuś W., Generation of graphene-like atoms structures by means of memetic algorithms, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), No.9447, pp.1, 2016
Burczyński T., Mrozek A., Kuś W., Generation of graphene-like atoms structures by means of memetic algorithms, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), No.9447, pp.1, 2016

Keywords:
carbon nano-structures, atom structures, memetic algorithms

41.Konowrocki R., Kukulski J., Walczak S., Generowanie gorących punktów w badaniach tribologicznych par ciernych hamulca kolejowego, POJAZDY SZYNOWE 2016, XXII SCIENTIFIC CONFERENCE RAIL VEHICLES - XXII KONFERENCJA NAUKOWA POJAZDY SZYNOWE, 2016-05-30/06-01, Bydgoszcz - Gniew (PL), pp.22-22, 2016
Konowrocki R., Kukulski J., Walczak S., Generowanie gorących punktów w badaniach tribologicznych par ciernych hamulca kolejowego, POJAZDY SZYNOWE 2016, XXII SCIENTIFIC CONFERENCE RAIL VEHICLES - XXII KONFERENCJA NAUKOWA POJAZDY SZYNOWE, 2016-05-30/06-01, Bydgoszcz - Gniew (PL), pp.22-22, 2016

Abstract:
Ciepło generowane w parach ciernych układów hamulcowych podczas szybkiego hamowania prowadzi często do pojawienia się gorących punktów (ang. hot-spots) na ich powierzchniach. Charakter i zakres intensywności tego zjawiska zależą w dużym stopniu od właściwości mechanicznych i termicznych materiałów takich par. Rozkład temperatury w elementach takich układach ciernych wpływa na ich zniekształcenia cieplne, inicjujące powyższe zjawisko. W pracy przedstawiono wyniki badań uzyskanych na obiektach układu hamulcowego pojazdów szynowych, przedstawiające takie zjawisko. Próby doświadczalne ilustrujące charakter przegrzanych obszarów w parach ciernych, wykonywano na stanowisku do badań hamulców w aplikacjach kolejowych. Do analizy rozkładu temperatur w badanych układach użyto kilku metod pomiarowych.

Keywords:
gorące punkty, układ hamulcowy, tarcie, hotspot, pojazdy dużych prędkości

42.Konowrocki R., Walczak S., Wysocki G., Experimental and numerical investigation of flexibility of railway wheels and wheelsets, POJAZDY SZYNOWE 2016, XXII SCIENTIFIC CONFERENCE RAIL VEHICLES - XXII KONFERENCJA NAUKOWA POJAZDY SZYNOWE, 2016-05-30/06-01, Bydgoszcz - Gniew (PL), pp.33-33, 2016
Konowrocki R., Walczak S., Wysocki G., Experimental and numerical investigation of flexibility of railway wheels and wheelsets, POJAZDY SZYNOWE 2016, XXII SCIENTIFIC CONFERENCE RAIL VEHICLES - XXII KONFERENCJA NAUKOWA POJAZDY SZYNOWE, 2016-05-30/06-01, Bydgoszcz - Gniew (PL), pp.33-33, 2016

Abstract:
The paper is devoted to the experimental and theoretical analysis of influence of elastic properties of wheelset stiffness on the vehicle-track interaction. Results of experimental measurements stiffness of wheelsets are shown. Some types of wheelsets are considered with different wheel-plate design. Exemplary simulation of railway vehicle interaction with flexible and rigid model of the wheelset is presented.

Keywords:
vibration, structural flexibility, railway wheelset, experimental investigation, numerical analysis

43.Bogacz R., Kurnik W., On some rotor-dynamical phenomena of high-speed trains, ARCHIVE OF APPLIED MECHANICS, ISSN: 0939-1533, DOI: 10.1007/s00419-014-0966-3, Vol.85, No.9, pp.1343-1352, 2015
Bogacz R., Kurnik W., On some rotor-dynamical phenomena of high-speed trains, ARCHIVE OF APPLIED MECHANICS, ISSN: 0939-1533, DOI: 10.1007/s00419-014-0966-3, Vol.85, No.9, pp.1343-1352, 2015

Abstract:
The paper is devoted to radial and out-of-plane vibration of railway wheels and to wheelset stability as key elements affecting high-speed vehicle dynamics, noise emission, and safety. In the present study, railway wheel tire is treated as a curved beam with various beam models, and the wheel plates are modeled as Winkler’s elastic foundation. New results are presented concerning the influence of the residual stresses on the corrugation and poligonalization of wheels as well as wave propagation in the wheel tire

Keywords:
Elastic wheel, Wheel–rail interaction, Traveling waves, Wheel poligonalization, Corrugation

44.Ramalli A., Byra M., Dallai A., Palombo C., Aizawa K., Sbragi S., Shore S., Portoli P., A Multiparametric Approach Integrating Vessel Diameter, Wall Shear Rate and Physiologic Signals for Optimized Flow Mediated Dilation Studies, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0326, pp.1-4, 2015
Ramalli A., Byra M., Dallai A., Palombo C., Aizawa K., Sbragi S., Shore S., Portoli P., A Multiparametric Approach Integrating Vessel Diameter, Wall Shear Rate and Physiologic Signals for Optimized Flow Mediated Dilation Studies, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0326, pp.1-4, 2015

Abstract:
Flow Mediated Dilation (FMD) is a technique widely used to assess the endothelial function by ultrasound. Ideally, both the brachial artery wall shear stress (stimulus) and the diameter change (effect) shall be estimated and monitored for up to 10 minutes, while blood flow is restricted by a cuff and then suddenly released. An inherent method's difficulty is maintaining the linear array probe aligned with the artery for such a long time. The problem is here faced by an integrated hardware/software approach that displays in real-time both the spatial velocity profiles and the diameter changes, and acquires raw data all over the exam.

Keywords:
component, Flow mediated dilation, FMD, wall shear stress, wall shear rate, diameter distension, ULA-OP

45.Piechór K., Calcium Waves in Thin Visco-Elastic Cells, MATHEMATICAL MODELLING OF NATURAL PHENOMENA, ISSN: 0973-5348, DOI: 10.1051/mmnp/20138313, Vol.8, No.3, pp.206-226, 2013
Piechór K., Calcium Waves in Thin Visco-Elastic Cells, MATHEMATICAL MODELLING OF NATURAL PHENOMENA, ISSN: 0973-5348, DOI: 10.1051/mmnp/20138313, Vol.8, No.3, pp.206-226, 2013

Abstract:
The model we consider treats the cell as a viscoelastic medium lling one of two kinds of thin domains (\shapes" of cells): the thin slab being a caricature of a tissue and the thin circular cylinder mimicking a long cell. This enables us to simplify the system of mechano-chemical equations. We construct abundant classes of explicit, but approximate, formulae for heteroclinic solutions to these equations.

Keywords:
calcium waves, mechano-chemical coupling, thin domains

46.Bogacz R., Czyczuła W., Pawlak-Burakowska A., Wpływ tłumienia na stateczność strumienia oscylatorów oddziałującego z belką. Stateczność przepływu cieczy, Symulacja w Badaniach i Rozwoju, ISSN: 2081-6154, Vol.3, No.2, pp.71-77, 2012
Bogacz R., Czyczuła W., Pawlak-Burakowska A., Wpływ tłumienia na stateczność strumienia oscylatorów oddziałującego z belką. Stateczność przepływu cieczy, Symulacja w Badaniach i Rozwoju, ISSN: 2081-6154, Vol.3, No.2, pp.71-77, 2012

Abstract:
W niniejszej pracy rozważana jest stateczność ruchu układu złożonego ze strumienia gęsto rozłożonej masy (oscylatorów) oddziałującego sprężyście lub lepko-sprężyście z belką na podłożu Winkera (np. modelującej rurę). Układ taki może być uproszczonym modelem układu pociąg - tor lub modelem rurociągu, przez który przepływa ciecz (dla uproszczenia nieściśliwa).

Keywords:
stateczność przepływu, ruch względny, tłumienie

47.Lewandowska B., Teoria informacji i jej zastosowania w biologii i w medycynie, XI Krajowe Forum Informacji Naukowej i Technicznej: Człowiek w przestrzeni informacyjnej, 2011-09-20/09-23, Zakopane (PL), pp.1, 2011
Lewandowska B., Teoria informacji i jej zastosowania w biologii i w medycynie, XI Krajowe Forum Informacji Naukowej i Technicznej: Człowiek w przestrzeni informacyjnej, 2011-09-20/09-23, Zakopane (PL), pp.1, 2011

Abstract:
Information theory and its application to the biology and medicine (Abstract). Information theory was founded by Claude E. Shannon in 1948. According to the C. Shannon theory, the information about an event is measured as the probability of the occurrence of the event. The cognitive possibilities which are related to the processes of knowing, understanding and learning something about the phenomenon under study, are employed also in the scientific researches into biology and medicine. A fair stock of information is contained in a living cell of an organism. The structure of an albumen is defined by the information contained in genes. The four-letter DNA language determines the laws governing the twenty-letter language of each albumen. Therefore, a genetitic information may be saved in the form of an one-dimensional instruction. C. Shannon defined mathematically the concept of the decisive information which is the measure of the decision taken on the classification of a sent out sign. In medicine making an exact diagnosis seems to be of key meaning. Proposing a suitable algorithm for generating the diagnosis process we arrive at the objectivity of the process since each illness may be regarded as a message obtained statistically. That is justified by the fact that the defined factors predispose us to some illnesses. In this way it is possible on the base of the theory of information to formalize the process of medical diagnosis.

48.Trzęsowski A., Tensility and compressibility of axially symmetric nanoclusters II; cylindrical nanoclusters, JOURNAL OF TECHNICAL PHYSICS, ISSN: 0324-8313, Vol.46, No.1, pp.9-22, 2005
49.Trzęsowski A., Tensility and compressibility of axially symmetric nanoclusters part I: simplified modelling, JOURNAL OF TECHNICAL PHYSICS, ISSN: 0324-8313, Vol.45, No.2, pp.141-153, 2004
50.Radulescu E., Wójcik J., Lewin P.A., Nowicki A., Nonlinear Propagation Model for Ultrasound Hydrophones Calibration in Frequency Range up to 100 MHz, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00124-0, Vol.41, No.4, pp.239-245, 2003
Radulescu E., Wójcik J., Lewin P.A., Nowicki A., Nonlinear Propagation Model for Ultrasound Hydrophones Calibration in Frequency Range up to 100 MHz, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00124-0, Vol.41, No.4, pp.239-245, 2003

Abstract:
To facilitate the implementation and verification of the new ultrasound hydrophone calibration techniques described in the companion paper (somewhere in this issue) a nonlinear propagation model was developed. A brief outline of the theoretical considerations is presented and the model’s advantages and disadvantages are discussed. The results of simulations yielding spatial and temporal acoustic pressure amplitude are also presented and compared with those obtained using KZK and Field II models. Excellent agreement between all models is evidenced. The applicability of the model in discrete wideband calibration of hydrophones is documented in the companion paper somewhere in this volume.

Keywords:
Nonlinear propagation modeling, Nonlinear propagation, JW model

51.Trzęsowski A., Self-Balance Equations and Bianchi-Type Distortions in the Theory of Dislocations, INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS, ISSN: 0020-7748, DOI: 10.1023/A:1024494112624, Vol.42, No.4, pp.711-723, 2003
Trzęsowski A., Self-Balance Equations and Bianchi-Type Distortions in the Theory of Dislocations, INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS, ISSN: 0020-7748, DOI: 10.1023/A:1024494112624, Vol.42, No.4, pp.711-723, 2003

Abstract:
We deals with two aspects of the geometric description of continuized Bravais monocrystals with many dislocations. First, a triad of vector fields is distinguished constituting a basis for the C∞-module of smooth vector fields tangent to the body. This moving frame defines its object of anholonomity as well as an intrinsic (“material”) Riemannian metric of the body. Second, these geometric objects are used to define both the notions of principal congruence of Volterra-type effective dislocations and principal local Burgers vector associated with these congruences. The main topics discussed are (i) self-balance equations of dislocations and secondary point defects generated by distributions of these dislocations; (ii) a linkage of the Bianchi classification of three-dimensional real Lie algebras with the physical classification of principal local Burgers vectors.

Keywords:
self-balance equations, Bianchi-type distortions, dislocations

52.Trzęsowski A., On the quasi-solid state of solid nanoclusters, JOURNAL OF TECHNICAL PHYSICS, ISSN: 0324-8313, Vol.44, No.4, pp.385-396, 2003
53.Filipczyński L., Wójcik J., Kujawska T., Łypacewicz G., Tymkiewicz R., Zienkiewicz B., Nonlinear Native Propagation Effect of Diagnostic Ultrasound Computed and Measured in Blood, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(00)00329-X, Vol.27, No.2, pp.251-257, 2001
Filipczyński L., Wójcik J., Kujawska T., Łypacewicz G., Tymkiewicz R., Zienkiewicz B., Nonlinear Native Propagation Effect of Diagnostic Ultrasound Computed and Measured in Blood, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(00)00329-X, Vol.27, No.2, pp.251-257, 2001

Abstract:
Nonlinear propagation effects produced by focused pulses in blood were measured over a 20-cm range, being inspired by diagnostic applications in cardiology. The initial and maximum pressures applied during measurements in blood were equal to 0.40 MPapp and 0.76 MPapp, while the pressure estimated at the patient body surface equalled 0.70 MPapp. Measurements of the frequency characteristic and the linearity of the ultrasonic probe used in experiments were performed in water. A numerical procedure developed previously was applied in blood to calculate the pressure distribution of its first and second harmonics along the beam axis. The comparison of numerical and measured distributions in blood at a temperature of 37°C showed rather good agreement. Using numerical methods, a proportional growth of the second harmonic with the increased applied initial pressure was first observed, and finally the maximum limiting effect was found. In this way, much higher level of harmonics could be obtained. However, there arise the questions of the transmitting system construction and of the nonuniform resolution in the case of harmonic imaging when increasing the applied initial pressure.

Keywords:
Ultrasound, Pulses, Nonlinear propagation, Blood, Cardiology

54.Wójcik J., Filipczyński J., Kujawska J., Temperature elevations computed for three-layer and four-layer obstetrical tissue model in nonlinear and linear ultrasonic propagation cases, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(98)00144-6, Vol.25, No.2, pp.259-267, 1999
Wójcik J., Filipczyński J., Kujawska J., Temperature elevations computed for three-layer and four-layer obstetrical tissue model in nonlinear and linear ultrasonic propagation cases, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(98)00144-6, Vol.25, No.2, pp.259-267, 1999

Abstract:
The authors computed temperature elevations in a three-layer and a four-layer tissue model, assuming the crucial obstetrical case when the ultrasonic pulse propagating through the abdomiinal wall and the fluid-filled bladder penetrates into soft fetal tissues.To consider nonlinear propagation, the authors applied a new theory of nonlinear increase of absorption recently developed by the first author. Computations were carried out for pulses with a carrier frequency of 3 MHz, duration time of 1.33 μs, and pulse repetition frequency of 3.3 kHz. Similar computations were carried out for a four-layer tissue model corresponding to the third trimester of gestation. The ceramic piezoelectric transducer 2 cm in diameter radiated the ultrasonic beam focused at a distance of 6.5 cm. The intensities at the radiating transducer (at the source) were ISAPA= 10 and 5 W/cm2. Temperature elevations and distributions were determined numerically for various values of low-amplitude absorption coefficients assumed to be the same as attenuation coefficients. It was shown in the three-layer tissue model that the maximum temperature elevation can be about 50% higher for nonlinear than for linear propagation.The maximum fetal temperature elevation in this case was 2.36°C for nonlinear and 1.84°C for linear propagation. The temperature elevation in the abdominal wall was lower than those temperatures when the attenuation of the abdominal wall was assumed to be a low value of 0.05 Np/cm.MHz (0.45 dB/cm.MHz). However, when it was increased to 0.16 Np/cm.MHz (1.4 dB/cm.MHz), the temperature elevation of the abdominal wall reached 3.2°C and the maximum fetal elevation was 1.65°C. In such cases, the abdominal wall became the principal source of heat production. In this case, the difference between fetal temperature elevations for nonlinear and linear propagation was only about 10%. The results obtained in the four-layer tissue model, in which the uterus tissue also was represented, show that temperature elevations in this case are about 3.6 times lower than in the three-layer tissue model, with comparable attenuation of the abdominal wall. Differences between nonlinear and linear propagation in the four-layer tissue model are negligible. The temperature elevations obtained were proportional to the pulse repetition frequency, without changing temperature distributions in the ultrasonic beam. In this manner, fetal temperature elevations can be reduced by reducing the repetition frequency.

Keywords:
Ultrasound, Nonlinear propagation, Temperature, Obstetrics

55.Filipczyński L., Kujawska T., Tymkiewicz R., Wójcik J., Nonlinear and linear propagation of diagnostic ultrasound pulses, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(98)00174-4, Vol.25, No.2, pp.285-299, 1999
Filipczyński L., Kujawska T., Tymkiewicz R., Wójcik J., Nonlinear and linear propagation of diagnostic ultrasound pulses, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(98)00174-4, Vol.25, No.2, pp.285-299, 1999

Abstract:
The effect of nonlinear propagation in fluid followed by soft tissue was studied both theoretically and experimentally for a most crucial case in obstetrical ultrasonography. For this purpose, short pressure pulses, with the duration time of 1.3 μs and a carrier frequency of 3 MHz, radiated by a concave transducer into water, with maximum intensities up to the value of 18 W/cm2, were computed and measured. The ultrasonic beam had the physical focus at the distance of 6.5 cm, where the highest focal intensity of ISPPA= 242 W/cm2 was obtained. In front of the transducer, at a distance of 7 cm, artificial tissue samples prepared on the basis of ground porcine kidney, with a thickness of 0.5, 1.5 and 3 cm, were placed in water. Pressure pulses and their spectral components were produced numerically and measured by means of a PVDF hydrophone in water before and after penetrating the tissue samples. The theoretical analysis and measurements were carried out, in every case, for two signal levels: for a high level assuring nonlinear propagation and for a low one where conditions of linear propagation were fulfilled. In this way, it was possible to compare directly the effects of nonlinear and linear propagation, in every case showing a good conformity of theoretical values with measured ones. A method of determination of the effective frequency response of the hydrophone was elaborated to enable quantitative comparisons of numerical and experimental results. The theoretical part of our study was based on a paper of Wójcik (1998), enabling us to compute the characteristic function of nonlinear increase of absorption. An agreement of up to 10% was obtained when comparing theoretical and measured values of these functions in the investigated beam in water and behind tissue samples. The results obtained showed that the recently given theory of nonlinear absorption, based on the spectral analysis and the elaborated numerical procedures, may be useful in various practical ultrasonic medical problems and also in technological applications.

Keywords:
Ultrasound, Pulses, Nonlinear propagation, Diagnostics