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Homogeneous and heterogeneous reactions are significant because many chemically reactive systems, such as biochemical systems, involve both types of reactions. This paper sheds light on the effects of homogeneous–heterogeneous reactions on magnetohydrodynamic blood flow through the catheterized multi-irregular vertically stenosed artery in non-Darcy porous media. The governing partial differential equations are simplified using mild stenosis approximations and then transformed into the computational domain to simplify the numerical calculations. It has been noticed that the fluid velocity and the flow rate go to their maximum values after a short time, and they decrease with fluctuation in the case of pulsating, but in the case of nonpulsatile, the behavior is steady. Moreover, an increase in the homogeneous heat reaction parameter decelerates the blood velocity, the flow rate and elevates the fluid temperature. Furthermore, the concentration reaches the steady state faster in the absence of a homogeneous thermal reaction. [ABSTRACT FROM AUTHOR]

Recently, aortic valve stenosis has received more attention, and its pathophysiology may be connected to persistent inflammation caused by micro-organisms. This paper investigates the transient electroosmotic hybrid nanofluid (blood model) flow in the annular region between the axially symmetric mild stenosis and the catheter tube. The non-Newtonian Sutterby fluid has been considered as a blood model due to the migration of gyrotactic micro-organisms in the bloodstream. The hybrid nanofluid consists of the suspension of the solid nanoparticles of the (Ag–Al 2 O 3 ) in pure human blood. The problem is simplified using the mild stenosis procedure and solved numerically utilizing the finite difference technique. It is observed that more effort is required to pump the blood in the case of the suspended hybrid nanoparticles than with suspended nanoparticles. Moreover, the results demonstrate that hybrid nanoparticles have better thermal properties than nanoparticles. [ABSTRACT FROM AUTHOR]

Selenium is an effective dopant in skutterudite-based thermoelectric materials. It strongly influences thermal transport properties due to effective phonon scattering. This study proposes a short-term fabrication route to Se-modified CoSb 3 -based materials. Alloy synthesis was conducted via self-propagating high-temperature synthesis. Subsequently, pulse plasma sintering consolidated all materials. As a result, thermoelectric materials with high electrical properties homogeneity were obtained. Seebeck potential mapping showed the measured deviation of the Seebeck coefficient for all fabricated samples was between 5 and 7%. A very low thermal conductivity (1.59 W m−1 K−1, at 573 K) was achieved for the highest doped sample, and one of the lowest reported results obtained for bulk skutterudite-based thermoelectric materials ever. This resulted in a low lattice thermal conductivity (1.51 W m−1 K−1, at 573 K). This led to the highest ZT (0.27 at 623 K) for the highest doped sample. [ABSTRACT FROM AUTHOR]

The accumulations of lipid low-density lipoprotein cholesterol (LDL-C) and other chemicals on the artery wall are known as atherosclerosis. Atherosclerosis can constrict the arteries and obstruct the blood flow. Our goal is to debate the model of unsteady pulsatile Cross fluid (blood model) flows through a vertical porous microchannel with multiple stenoses under the influence of thermal radiation and Joule heating. The equations of momentum, energy, and LDL-C concentration have been simplified with the help of mild stenosis approximation. Then they have been solved numerically by using the finite difference method. It is noticed that the blood velocity increases and reaches a steady state in the case of non-pulsating flow, while the blood velocity fluctuates in the case of pulsating flow. Moreover, the value of LDL-C concentration in the case of a chemical reaction is lower than in the absence of a chemical reaction. [ABSTRACT FROM AUTHOR]

In the current problem, we aim to discuss the heat transfer of pulsatile unsteady fractional Maxwell fluid (blood) flow through a vertical stenosed artery with body acceleration. The concept of fractional Cattaneo model will modify the energy equation. We will get the solutions using Laplace and finite Hankel transformations. The inverse of the transformed functions will be calculated numerically. It is observed that, the heat relaxation time causes a delay in the heat transfer until a critical time. In addition, the heat transfer increases sharply to take its maximum value at a critical value of time then it decreases to reach the steady state. Moreover, the blood velocity, the flow rate, and the shear stress continue to fluctuate during the time period due to the pulsatile phenomenon and body acceleration. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) are now widely used because of their synthesis compatibility and less toxicity in several biomedical applications such as cancer treatment. From the fluid mechanics point of view, we examine the behavior of a mixture of gold and Titanium Oxide nanoparticles, which suspended in the blood as a base fluid in the diseased coronary artery. The main goal of this paper is to examine and shed light on the hybrid nanofluid flows through a vertical diseased artery in the presence of the catheter tube with heat transfer. The mathematical model is established and then solved with the Laplace and the finite Hankel transforms. The inverse of the transformed functions has been calculated numerically. The velocity, the pressure, the impedance and the heat transfer are discussed graphically. It is noteworthy to mention that the mixture of the nanoparticles dispersed in the blood needs high pressure to push it. The impedance of blood is proportional to the overall volume concentration of the nanoparticles and Reynolds number. [ABSTRACT FROM AUTHOR]

The paper presents an experimental procedure based on micro-scratching to detect stresses in the ground layer of panel paintings. The method relies on the fact that cracking of the material during a micro-scratching test is the outcome of a combination of local force applied by an indenter and the stresses present in the material. The critical normal load at which damage appears during the test has a strong correlation with the stress in the material. The method, although not providing absolute values of stress, is sensitive to stress magnitude and direction, only micro-destructive, and attractive for monitoring stress changes caused by relaxation processes also in multi-layer materials. The presented tests were performed on artistic materials for which information on stress relaxation is particularly important when developing strategies for their storage and transportation. [ABSTRACT FROM AUTHOR]

This paper presents the results of the optimization of electrophoretic deposition parameters for manufacturing of nc-TiO2/ chitosan composite coatings on X2CrNiMo17-12-2 steel as well as characterization of their microstructure, electrochemical properties and adhesion to the substrate. The parameters of the deposition, such as composition, pH and zeta potential of suspensions as well as voltage and process time were investigated. The microstructure of the coatings was characterized using scanning and transmission electron microscopy. Obtained coatings were crack-free and uniform. The adhesion strength to the substrate was measured by scratch-test method. The deposited coatings improve corrosion resistance of steel, what was confirmed by the results of the potentiodynamic polarization test in Ringer's solution. [ABSTRACT FROM AUTHOR]

This study is concerned with the surgical technique for the injection of a catheter through arteries with overlapping stenosis in the presence of externally applied magnetic field and Hall currents influences. The nature of blood is analyzed mathematically by considering it as a micropolar fluid. The analysis is carried out for an artery with a mild stenosis. The governing equations with the corresponding boundary conditions solved numerically using Crank–Nicolson implicit finite difference scheme. The numerical technique give excellent agreement for axial velocity of the fluid, the circumferential microrotation, the wall shear stress distribution and the contour plots of stream lines. The obtained results show that the value of axial velocity is higher for a Newtonian fluid than that for a micropolar fluid model, the effect of suitable moving magnetic field (Hall currents influences) accelerates the speed of blood, the size of trapped bolus for the stream lines decrease if the spinning movement of the fluid molecules have considerable value regardless of small or large size of the fluid molecules and the flow of fluid is better with increasing the Hall current effect and the size of trapping bolus increase clearly by increasing the maximum height of stenosis where the fluid moves as a bulk. [ABSTRACT FROM AUTHOR]

In this study, chitosan coatings were electrophoretically deposited (EPD) on near-β Ti-13Nb-13Zr alloy. The influence of colloidal solution composition and EPD parameters on the quality of chitosan coatings was investigated. It was established that the uniformity of as-deposited chitosan coatings is highly dependent on the chemical composition of the solution used for EPD, the pH, electrophoretic mobility and zeta potential of chitosan colloidal molecules, as well as EPD parameters, such as potential difference value and deposition time. The microstructure of the coatings was investigated using electron microscopy and X-ray diffractometry. The coatings 350 nm thick were homogeneous and exhibited an amorphous structure. The coatings had low hardness and Young's modulus. The effect of surface of the substrate preparation prior to coating deposition on the adhesion of chitosan coatings to the Ti-13Nb-13Zr alloy was also investigated. The coatings exhibited good adhesion to the non-acid-etched surface of the titanium alloy. [ABSTRACT FROM AUTHOR]

The paper presents research on coatings with advanced architecture, composed of a Cr/Cr2N ceramic/metal multilayer and graded carbon layers with varying properties from Cr/a-C:H to a-C:N. The microstructure of the coatings was analysed using transmission electron microscopy and Energy Dispersive Spectroscopy, the mechanical properties were tested by nanoindentation, spherical indentation, and scratch testing, and tribological tests were also conducted. The proper selection of subsequent layers in graded coatings allowed high hardness and fracture resistance to be obtained as well as good adhesion to multilayers. Moreover, these coatings have higher wear resistance than single coatings and a friction coefficient equal to 0.25. [ABSTRACT FROM AUTHOR]

White pine blister rust (WPBR, Cronartium ribicola ) is a fungal pathogen and a threat to whitebark pines ( Pinus albicaulis ). It has a complex life cycle that requires two hosts, a white pine and an alternate host, typically a currant or gooseberry ( Ribes spp.). WPBR is transmitted between hosts by means of two types of airborne spores whose average dispersal distances differ by several orders of magnitude. In this paper, we introduce a discrete-time model based on the life cycle of WPBR. We then extend this model to include a continuous spatial domain, disease-induced mortality in the pines, and a latency period. After each extension, we find the pathogen׳s asymptotic speed of invasion analytically using exponential transforms and the method of steepest descent. Our results show that invasion speeds are strongly reduced by the latency period in the pine host. In addition, these speeds are highly dependent on the carrying capacity and infectiousness of each host type. If these parameters are sufficiently small, high mortality in pines may stop the spread of WPBR completely. [ABSTRACT FROM AUTHOR]

The paper presents the deformation and fracture analysis of coating-substrate systems during spherical indentation. CrN and TiN ceramic coatings with a thickness of 1-5 μm were tested using 10 to 200 μm tip radius spherical indenters. The typical results of indentation tests i.e. force-penetration depth curves were transformed into stress-strain curves using an algorithm developed by the author. The test results are compared with the results of numerical analysis conducted using FEM modelling. Such a complex analysis allows users to determine the level of tensile stress leading to the formation of cracks observed using SEM and TEM microscopy, and to define the failure maps for the coating substrate-systems. [ABSTRACT FROM AUTHOR]

Highlights: [•] Deposition of new kind of nanocomposite coatings Cr x C/a-C:H for tribological applications. [•] Analysis of hardness and elasticity modulus based on nanoindentation results. [•] Effect of microstructure and amount of ceramic nanograins on mechanical properties. [•] Analysis of fracture toughness and wear mechanisms. [•] Discussion on optimization coatings architecture to obtain an excellent mechanical and tribological properties. [Copyright &y& Elsevier]

Abstract: A protective quasicrystalline AlFeCu coating was deposited on TIMETAL 834 substrate by nonreactive magnetron sputtering in order to improve resistance of the alloy to oxidation. Microstructure characterisation of the substrate and the coating was performed by analytical scanning- and transmission electron microscopy as well as X-ray diffractometry. Depending on annealing temperature and time, the deposited coating (2.7μm thick) has a different microstructure. The coating in Specimen 1 (annealed 600°C/4h in vacuum) consisted of two zones: outer, composed of Al5Fe2 and Al2Cu3 phases and inner, in which only quasicrystalline ψ phase was present. The coating in Specimen 2 (annealed 600°C/4h+700°C/2h in vacuum) was fully quasicrystalline and consisted of icosahedral ψ phase. Both coatings exhibit higher microhardness than the substrate material. It was established that the applied surface treatment essentially improves oxidation resistance of the alloy tested at 750°C during 250h in static air. Sample weight gain was 60% lower than in the case of uncoated sample. Oxide scale spallation occurred for uncoated alloy while the coated one did not show any spallation. It was found that the very brittle scale formed during oxidation on the uncoated alloy was consisting of TiO2, while that on the coated one consisted mainly of α-Al2O3. [Copyright &y& Elsevier]

This article is concerned with the analysis of a dusty model for the axi-symmetric flow of blood through coaxial tubes such that the outer tube with an axially nonsymmetreic but radially symmetric mild stenosis and the inner tube have a balloon (assumed that is axi-symmetric in nature). The mild stenosis approximation is used to solve the problem. To estimate the effect of the stenosis shape, a suitable geometry has been considered such that the axial shape of the stenosis can be changed easily just by varying a parameter (referred to as the shape parameter). The model is also employed to study the effect of the volume fraction density of the particles C, the maximum height attained by the balloon δ2, the radius of the inner tube, which keeps the balloon in position κ, and the axial displacement of the balloon xd. Flow parameters such as velocity, the resistance to flow (the resistance impedance), the wall shear stress distribution in the stenotic region and its magnitude at the maximum height of the stenosis (stenosis throat) have been computed numerically for different shape parameters n, C, δ2, κ, and xd. It is shown that the resistance to flow decreases with increasing values of the parameter determining the stenosis shape n and the axial displacement of the balloon xd, while the resistance to flow increases with the volume fraction density of the particles C, the radius of the inner tube, which keeps the balloon in position κ, and the maximum height attained by the balloon δ2. The magnitudes of the resistance to flow are higher in the case of a dusty fluid model than in the case of a Newtonian fluid model. The wall shear stress distribution in the stenotic region and its magnitude at the maximum height of the stenosis possess a character similar to the resistance to flow with respect to C, δ2, κ, and xd. Finally, the effect of the volume fraction density of the particles C, δ2, and xd on the velocity profile are discussed. [ABSTRACT FROM AUTHOR]

A micropolar model for blood simulating magnetohydrodynamic flow through a horizontally nonsymmetric but vertically symmetric artery with a mild stenosis is presented. To estimate the effect of the stenosis shape, a suitable geometry has been considered such that the horizontal shape of the stenosis can easily be changed just by varying a parameter referred to as the shape parameter. Flow parameters, such as velocity, the resistance to flow (the resistance impedance), the wall shear stress distribution in the stenotic region, and its magnitude at the maximum height of the stenosis (stenosis throat), have been computed for different shape parameters, the Hartmann number and the Hall parameter. This shows that the resistance to flow decreases with the increasing values of the parameter determining the stenosis shape and the Hall parameter, while it increases with the increasing Hartmann number. The wall shear stress and the shearing stress on the wall at the maximum height of the stenosis possess an inverse characteristic to the resistance to flow with respect to any given value of the Hartmann number and the Hall parameter. Finally, the effect of the Hartmann number and the Hall parameter on the horizontal velocity is examined. [ABSTRACT FROM AUTHOR]

Abstract: Multilayers of alternate Cr/CrN coatings deposited on AISI 301 steel by a pulsed Nd:YAG laser have been tested by microindentation to measure both hardness and Young''s modulus. Critical load L C has been determined by scratch test. The total thickness of multilayers was 1 µm, and the bilayer period Λ varied from between 60 nm and 1000 nm. TEM and EDS techniques were used for investigating and analyzing the microstructure of the multilayers. The results of these measurements show that the mechanical properties of Cr/CrN multilayers depend on the bilayer period. The maximum improvement in performance over a single layer of CrN has been found to be Λ at 250 nm, particularly in terms of critical load and Young''s modulus. [Copyright &y& Elsevier]

As a result of loading with an external force during the wear process, coating deforms uniformly. After a certain limit load is exceeded, coating deformation is localised through the formation of the so‐called shear bands. It has been showed experimentally the process of shear bands formation. The microstructural characterisation before and after the mechanical tests was performed using scanning and transmission electron microscopy (SEM and TEM) on cross‐sections of the samples. The analysis indicated that in the case of multilayer coatings where the ratio of the metallic to the ceramic phase is 1:1, the shear bands are formed at an angle of 45°. With a greater proportion of the ceramic phase to metallic (ratio 1:2), the shear band changed the shear angle from ∼45° to ∼90°. Mechanical in situ tests were carried out in the chambers of SEM and TEM. The scratch tests in the SEM were done with the simultaneous observation of the phenomena occurring on the surface of the tested materials showed that at a scratch force of 0.04 N, the additional outer a‐C:H layer was damaged, which was shown in the form of a fault in the force–displacement diagram, and in the form of splits visible in the SEM image. However, the application of this additional layer had a positive effect on the wear mechanism of the entire coating structure. The test also indicated that in the case of coatings with phases ratio 1:2 and 1:4 (metallic to ceramic), the characteristics of the brittle material were demonstrated, unlike the coating with a 1:1 phase ratio, where plastic properties predominated. However, for the 1:2 phase ratio coating, the chip was more ductile than for the chip formed when testing a 1:4 phase ratio coating. For in situ mechanical testing in the TEM, a straining holder was used. The test showed that the shear band angle for a 1:1 ratio coating has changed from 45° to 90° due to the different direction of force interaction. [ABSTRACT FROM AUTHOR]

One of the fundamental problems in ecology is understanding the ragged ups and downs in abundance that characterize many natural populations. Recent advances in nonlinear dynamics suggest that even the "noisiest" variation may have its origin in simple deterministic mechanisms. Here we review both the theory and the evidence and conclude that "strange" attractors, the chaotic counterparts to equilibria and limit cycles, may play an important role in ecological systems. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 31-year-old Australian man who had cardiac arrest after ingesting natural plant leaves called khat. It states that he was talking and laughing with his girlfriend when he became unresponsive and was taken to the hospital. It mentions that an echocardiogram showed severe ventricular contractile impairment and developed myoclonus and severe hypoxic brain damage. It notes that he is a heavy user of khat which causes hyperactive state, anorexia, and insomnia.

Wstęp. Resekcje trzustki należą do najtrudniejszych procedur chirurgicznych i nadal są obarczone dużym odsetkiem powikłań. Cel pracy. Celem pracy była analiza wczesnych powikłań pooperacyjnych po resekcjach trzustki. Materiał i metoda. Analizie poddano przebiegi pooperacyjne u 100 chorych po zabiegach resekcyjnych trzustki. Wyniki. Najczęściej wskazaniami do resekcji trzustki były: rak (brodawki Vatera - 30, trzustki - 24), guzy zapalne (16), łagodne guzy torbielowate (12); w 8 przypadkach resekcja trzustki (dystalna) była elementem składowym operacji z powodu zaawansowanego raka żołądka; pozostałe to: chłoniak (2), guz neuroendokrynny (2), gruczolak z dysplazją dużego stopnia brodawki Vatera (2), GIST (1), IPNM (1), fibromatoza (1), uraz (1). Najczęściej wykonywaną operacją było częściowe wycięcie narządu (77: resekcja proksymalna - 38, resekcja dystalna - 39); całkowitą pankreatektomię wykonano u 20 chorych; u 3 chorych operacja ograniczyła się do wycięcia guza. Dominującymi powikłaniami pooperacyjnymi były przetoki trzustkowe (7%) oraz krwotoki (5%). Tylko 1 przypadek przetoki był leczony operacyjnie. We wszystkich przypadkach powikłań krwotocznych konieczna była interwencja chirurgiczna (u 2 chorych - kilkakrotna). W okresie pooperacyjnym zanotowano 4 zgony (4%). Wnioski. Chirurgia trzustki nadal pozostaje dyscypliną bardzo trudną, wymagającą nie tylko doskonałej techniki operacyjnej, ale również umiejętności leczenia powikłań pooperacyjnych. [ABSTRACT FROM AUTHOR]

Wstęp. Rak przełyku jest szóstą przyczyną zgonów z powodu chorób nowotworowych i ósmym najczęstszym nowotworem na świecie. Pięcioletnie przeżycie rzadko przekracza 40% i najczęściej wynosi 15-25%. Rak płaskonabłonkowy, zajmujący najczęściej górną i środkową część przełyku, może być poddany radiochemioterapii z intencją radykalności leczenia. Chirurgia, otwarta i laparoskopowa, zwłaszcza w przypadku nowotworu dolnej części przełyku, zajmuje główne miejsce w postępowaniu terapeutycznym. Cel pracy. Celem pracy była analiza dostępnych opcji terapeutycznych i wczesnych wyników leczenia w oparciu o własne doświadczenia. Metodyka. Dokonano retrospektywnej analizy historii chorób 143 pacjentów, z rozpoznaniem raka przełyku lub połączenia przełykowo-żołądkowego (typ I-II według klasyfikacji Siewerta). Dokonano analizy typu histopatologicznego, zaawansowania procesu nowotworowego (TNM), metod i wczesnych wyników leczenia. Punktami końcowymi były wczesne powikłania po leczeniu operacyjnym z intencją wyleczenia: nieszczelność zespolenia, śmiertelność szpitalna. Wyniki. W badanej grupie zabieg resekcyjny wykonano u 53 pacjentów (37,06%), u 20 chorych wykonano zabieg założenia protezy samorozprężalnej do przełyku (13,98%). Pozostali chorzy ze względu na zaawansowanie procesu nowotworowego zostali poddani zabiegom paliatywnym (założenie PEG, paliatywna chemioterapia, paliatywna radioterapia) lub zostali zdyskwalifikowani z leczenia. W grupie chorych poddanych zabiegowi operacyjnemu z intencją wyleczenia było 8 (15%) przypadków nieszczelności połączenia przełykowo-żołądkowego i 6 (11,3%) zgonów. W grupie chorych poddanych zabiegowi protezowania przełyku u jednego chorego wystąpiła perforacja podczas zabiegu, która wymagała zaopatrzenia przez laparotomię. Powikłanie to zakończyło się zgonem pacjenta. Wnioski. Wyniki potwierdzają konieczność poszukiwania nowych metod diagnostycznych, które umożliwią wczesne rozpoznanie nowotworu, jak również potrzebę rozwoju metod leczenia systemowego. [ABSTRACT FROM AUTHOR]

• The biomimetic approach to the organic coating design. • Tribological and biological parts of advanced organic multilayer coating. • The gas exchange in amorphous PTFE coating structure. Direct oesteointegration between a polymeric implant made of a polymer such as a PEEK and host tissues involves direct connection via surface energy, which can be increased by plasma surface modification. Thin coatings are preferably produced by deposition from the gaseous phase (CVD - chemical vapour deposition). In the frame of this research study, PEEK substrates were modified by the PTFE + SiO 2 /organic silicone multilayer structures that were designed via a biomimetic concept based on algae shell structures. The coatings exhibited mechanical wear resistance and ensured adequate human fibroblast cell proliferation. The proliferation was characterized using confocal microscopy. The analysis together with detailed microstructural characterization with transmission electron microscopy techniques (TEM) established a complex correlative microscopy characterization and allowed the determination of the mechanical and biological features of the coatings. High-resolution TEM (HRTEM) observations revealed possibilities of gas circulation in between the substrate material and the outside environment without making direct contact. [ABSTRACT FROM AUTHOR]

Measurement of cardiac output is an integral part of patient management in the intensive care unit. FloTrac/Vigileo is a continuous cardiac output monitoring device that does not need re-calibration. However its reliability has been questioned in some studies, especially involving surgical patients. In this study, we evaluated the comparability of FloTrac/Vigileo and transthoracic Doppler echocardiography in 53 critically ill patients requiring continuous cardiac output monitoring. Most of these patients had septic or cardiogenic shock. Cardiac output was measured by both FloTrac/Vigileo and transthoracic Doppler echocardiography. The bias and precision (mean and SD) between the two devices was 0.35 +/- 1.35 l/minute. The limits of agreement were -2.3 to 3.0 l/minute (%error = 49.3%). When patients with irregular heart rhythms and aortic stenosis were excluded, the bias and precision was 0.02 +/- 0.80 l/minute (n = 42). The limits of agreement were -1.55 to 1.59 l/minute (%error = 29.5%). Patient demographics (body surface area, gender and age) did not affect the bias, but there was a mild tendency for FloTrac/ Vigileo to register a higher cardiac output at high heart rates. Changes in cardiac output for two consecutive days correlated well between the two methods (r = 0.86; P < 0.001). In summary, with the exceptions of patients with irregular heart rhythms and significant aortic stenosis, FloTrac/Vigileo is clinically comparable to transthoracic Doppler echocardiography in cardiac output measurements in critically ill patients. [ABSTRACT FROM AUTHOR]

Celem pracy jest przedstawienie zastosowania pasty Askina® Calgitrol® w leczeniu oparzeń. W pracy wykorzystano metodę badawczą - studium przypadku. Badania zostały przeprowadzone w Samodzielnym Publicznym Zespole Opieki Zdrowotnej we Wschodnim Centrum Leczenia Oparzeń i Chirurgii Rekonstrukcyjnej w Łęcznej. W badaniach uczestniczyli dwaj mężczyźni w wieku 61 lat i 26 lat. Obydwaj pacjenci wyrazili zgodę na badanie oraz na wykorzystanie wyników do niniejszej pracy. Podczas stosowania pasty badani mężczyźni odczuwali złagodzenie bólu i nie czuli dyskomfortu spowodowanego surowiczym wysiękiem z rany oparzeni owej. Pomimo powstałej powłoki, jaką stworzył preparat Askina® Calgitrol®, pacjenci nie odczuwali ściągania skóry twarzy. Po usunięciu zastosowanej pasty skóra wyglądała na nawilżoną. [ABSTRACT FROM AUTHOR]

The lifetime of protective coatings is usually limited due to the formation of defects in the form of cracks, resulting in the destruction of coatings. Understanding the initial stages of structural defects during the wearing process of coatings on the nano- and atomic scale allows for predictions of the lifetimes of fabricated coatings. The main goal of the presented work was to study the nanoscale wear mechanisms of advanced Zr/Zr x N multilayer coatings both ex situ and in situ. These coatings allow for reduced failures due to crack deflection characteristics and the ability for layers by layer coating remove. The analysis indicated thatto increase the quality of the coating's adhesion, it was necessary to decrease the thickness of the metallic buffer layer. This decrease caused the formation of much finer, equiaxial grains, resulting in the stabilization of the isotropic residual stress of the total coating and the improved resistance to the formation of defects in the form of cracks. The adequate thickness of the buffer layer is a very important aspect in the explanation of the differences in the quality of coating adhesion; however, it is insufficient to explain differences in its wear resistance properties. The detailed microstructure study revealed that the nature of the tribofilm formed during the wear process might have a significant impact on the speed of its progression. The analysis showed that at higher phase ratios, namely, 1:4, with a larger amount of ceramic phase in the multilayer structure, a lower amount of the unfavourable hard tribofilm was produced. A similar behaviour was observed in the scratch experiments performed in situ of the scanning electron microscope. In the case of plastic dominated deformation, continuous chips were formed remaining within the scratch track. In the coating with ceramic dominated properties, the chips were discontinuous and moved away from the scratch track during the test. To have adequate coating adhesion to the substrate and appropriate wear resistance, it was necessary to limit the thickness of not only the first metallic buffer layer but also all the other metallic interlayers in the ceramic/metallic multilayer system. Limiting this thickness allowed for the stabilization of the residual stress at the substrate/coating interface and resistance to the formation of defects in the form of cracks, and it increased coating adhesion while minimizing the formation of unfavourable tribofilm, which accelerates the wear process. [ABSTRACT FROM AUTHOR]

Metallic nanoparticles effect on magnetohydrodynamics (MHD) micropolar blood flow through a vertical artery with an overlapping stenosis is investigated. Conservation of mass, momentum, and energy governing partial differential equations are transformed into ordinary differential equations by means of mild stenosis assumptions. Solutions for velocity, microrotation, stream function, temperature, resistance impedance, and wall shear stress are calculated and expressed through graphs against various emerging physical parameters. It is observed that as the nanofluid volume fraction Φ increases, the velocity and wall shear stress increase, while resistance impedance has an inverse trend. It is also found that as the nanofluid volume fraction Φ increases, the temperature decreases. Moreover, the trapping phenomena in the stenosed region are introduced through graphs. These findings illustrate that nanoparticles' technique could be a promising therapeutic strategy against arterial diseases. [ABSTRACT FROM AUTHOR]

Achieving fast and strong adhesion to jawbone is essential for dental implants. Thin deposited films may improve osseointegration, but they are prone to cohesive and adhesive fracture due to high stresses while screwing the implant into the bone, leading to bared, less osteoconductive substrate surfaces and nano- and micro-particles in the bone. Aim of this work is the investigation of the cohesion and adhesion failure stresses of osteoconductive tantalum, titanium, silicon, zirconium and aluminium oxide and diamond-like carbon films. The tribological behaviour under dry and lubricated conditions (Ringer solution) reveals best results for diamond-like carbon, while cohesion and adhesion of zirconium oxide films is highest. [ABSTRACT FROM AUTHOR]

Complex microstructure analysis of TiN/Ti/a-C:H multilayer coatings, subjected to mechanical and biological tests, were performed by means of transmission electron microscopy (TEM) and confocal scanning laser microscopy (CSLM), respectively. Influence of interface numbers and phase ratios on coating properties was studied. Thin films were fabricated by a hybrid PLD technique (PLD supported by magnetron sputtering). The a-C:H phase was characterized by an amorphous structure, while TiN was built of columnar crystallites. Multilayer coatings contained sequentially deposited TiN and a-C:H layers with thin metallic Ti inter- layers deposited at each interface. Mechanisms of mechanical wear of analyzed systems were presented focusing on the cracking propagation revealed in the scratch test. Biological tests were done basing on smooth muscle cells adhesion to coating surfaces. An increase of TiN phase in the coating led to improvement of mechanical properties, while the carbon phase improved the biological behavior. Coatings comprising a higher rate of the carbon (a-C:H) revealed brittleness and were prone to delaminating. Optimal properties from the mechanical and biological point of view were stated for 8xTiN/Ti/a-C:H coating with 1:1 phase ratio (TiN to a-C:H). [ABSTRACT FROM AUTHOR]

In this work a microporous oxide layer was formed on two phase (a+β) Ti-6Al-7Nb titanium alloy by the micro-arc oxidation process in an electrolyte containing (CH3COO)2CaH2O and Na3PO4. The thickness of the surface layer was in the range of 2.7 µm-3.6 µm. Microstructure of the surface layer and the substrate alloy was characterized with use of scanning- and transmission electron microscopy as well as by X-ray diffractometry. The microstructure of the surface layer consisted of TiO2 rutile and anatase nanocrystals as well as of amorphous regions containing mainly Ti, Ca and O atoms and a minority of P, Al and Nb ones. The surface layer was highly porous. The open pores, with diameter up to 6 µm, were homogenously distributed in the specimen surface. Electron tomography was used to investigate the pores morphology and spatial distribution. It was found that open pores exhibited a complex geometry. The closed pores had nearly spherical shape. Adhesion of the surface layer to the titanium alloy substrate was investigated by means of the scratch-test. The value of critical load LC2=14 N indicates a good layer adhesion to the underlying substrate. [ABSTRACT FROM AUTHOR]

The aim of this study was to improve properties of blood contacting materials such as polyurethane, in a form of intelligent, self-organizing and self-controlling coatings, which allow the selective mobilization and colonization of the endothelial cells on their surface. The prepared multilayer polyelectrolyte scaffolds were cross-linked chemically by EDC/NHS reagents in order to control their physicochemical properties and thus improving potential to endothelialization. Four types of coatings, i.e. non-cross-linked, cross-linked by 260 mM, 400 mM and 800 mM EDC reagent, were investigated. Their comparison was performed based on the results of the surface topography measurements using Atomic Force Microscopy (AFM), cellular morphology and proliferation analysis using Confocal Laser Scanning Microscopy (CLSM) and the mechanical properties examinations. The optimal multilayer rigidity and surface roughness parameters were found for an effective control of the endothelial cells growth. Surface topography analysis indicated an increase in the coating's roughness due to application of higher EDC cross-linker concentrations. Mechanical studies revealed that cross-linking caused a significant increase in the hardness and elastic modulus. The results from the cellular experiments allowed the conformation that 400 mM cross-linked PLL/HA films possess desired properties. [ABSTRACT FROM AUTHOR]

The article discusses a study which evaluated the comparability of Flotrac/Vigileo and transthoracic Doppler echocardiography in the measurement of cardiac output in critically ill patients. It also aimed to identify if the bias between the two devices can be affected by demographic data and heart rate. Findings suggest that with the exceptions of patients with irregular heart rhythms and significant aortic stenosis, both devices are comparable in cardiac output measurements.

A mathematical model for blood flow through an elastic artery with overlapping stenosis under the effect of induced magnetic field is presented. The present theoretical model may be considered as a mathematical representation to the movement of conductive physiological fluid through coaxial tubes such that the inner tube is uniform and rigid, representing a catheter tube, while the outer tube is an anisotropically tapered elastic cylindrical tube filled with a viscous incompressible electrically conducting fluid, representing blood. The analysis is carried out for an artery with mild local narrowing in its lumen, forming a stenosis. Analytical expressions for the stream function, the magnetic force function, the axial velocity, the axial induced magnetic field, and the distribution of the current density are obtained. The results for the resistance impedance, the wall shear stress distribution, the axial velocity, the axial induced magnetic field, and distribution of the current density have been computed numerically, and the results were studied for various values of the physical parameters, such as the the Hartmann number Ha, the magnetic Reynolds number Rm, the taper angle , the maximum height of stenosis δ, the degree of anisotropy of the vessel wall n, and the contributions of the elastic constraints to the total tethering K. Nous présentons un modèle mathématique de l'écoulement sanguin dans une artère élastique avec chevauchement de sténoses sous l'influence d'un champ magnétique. Ce modèle théorique peut être vu comme une représentation mathématique du mouvement d'un liquide physiologique conducteur à travers des tubes coaxiaux où le tube intérieur est uniformément rigide et représente le cathéter, alors que le tube extérieur est un cylindre élastique anisotropiquement conique rempli d'un liquide visqueux incompressible et conducteur qui représente le sang. L'analyse est faite ici pour une artère avec un léger étranglement local formant une sténose dans son lumen. Nous obtenons des expressions analytiques pour la fonction de courant, la force magnétique, la vitesse axiale, le champ magnétique axial induit et la distribution de densité de courant. Les résultats pour l'impédance résistive, la distribution de la contrainte de cisaillement à la paroi, la vitesse axiale, le champ magnétique axial induit et la distribution de densité de courant, ont été évalués numériquement. Les résultats ont été étudiés pour différentes valeurs des paramètres physiologiques, comme le nombre de Hartmann Ha, le nombre magnétique de Reynolds Rm, la conicité , la hauteur maximale des sténoses δ, le degré d'anisotropie de la paroi du tube n et la contribution des contraintes élastiques à la liaison totale K. [ABSTRACT FROM AUTHOR]

Cladonia rangiferina is a bushy lichen of the genus Cladonia and has a multi-regional distribution. This plant contains usnic acid as the main biologically active substance and has been tested against some opportunistic microorganisms. Among the studied C. rangiferina extracts, only glycerol extracts obtained at an extraction temperature of 40°C were biologically active and only against Gram-positive microorganisms (S. aureus) and fungi (C. albicans). The antimicrobial activity of the extracts decreased if the extraction temperature was raised to 90°C. The results showed that C. rangiferina lichen could be a potential rich source of effective antimicrobial agents. [ABSTRACT FROM AUTHOR]

SiO 2 /Ni nanocomposite coatings containing well-dispersed SiO 2 nanoparticles were electrodeposited from a sulphate bath with and without the addition of polyethylenimine (PEI) as a cationic surfactant. The surface morphology and microstructure in the cross-sections of the deposited nanocomposites were examined by scanning electron microscopy. More detailed microstructure characterization was performed using transmission, scanning-transmission and high resolution transmission electron microscopy. It was determined that the addition of 0.05 g/L and 0.1 g/L of PEI allows the incorporation of SiO 2 nanoparticles in the nickel matrix to be increased in comparison with the nanocomposite deposited without a surfactant. Based on high spatial resolution microanalysis, performed using high count rate energy dispersive spectroscopy of characteristic X-rays in the scanning-transmission mode, the distribution of SiO 2 nanoparticles in the nanocomposite was visualized on elemental maps. Image analysis of the electron microscopy images enabled the mean equivalent circle diameters of grains in the nickel matrix to be determined, together with the volume fraction of SiO 2 nanoparticles in the nanocomposites. The volume fraction of SiO 2 clusters in the SiO 2 /Ni + PEI nanocomposites with the addition of 0.05 g/L and 0.1 g/L of PEI is equal to 18.4% and 13.3%, respectively. Furthermore, the PEI addition allows the nickel grain size in the matrix to be reduced. The combination of different imaging techniques confirmed that PEI is not only present as a surfactant in the electrolytic bath, but also incorporates into the microstructure of the nanocomposite. Nanocomposites electrodeposited in the presence of 0.05 g/L of PEI exhibit higher hardness, good tribological properties and improved corrosion resistance. Although increasing the PEI concentration in the bath up to 0.1 g/L strongly promotes grain size reduction and increase of the SiO 2 volume fraction, it also causes an increase in the PEI fraction embedded in the microstructure, which results in deterioration of the properties of the SiO 2 /Ni + PEI nanocomposites. [ABSTRACT FROM AUTHOR]

The present paper describe the issue of tool materials wear in a high temperature conditions. The investigations were performed at the cast steel tool material at the tribological contact to the structural steel. The investigations aim was to determine the role of microstructure in a tribological properties between the structural steel and tool material. The results of such investigation could be referenced to the industry conditions and could answer about the problems of tool materials wear. The observations of the wear mechanisms were referred to the microstructure of the mill rolls. The laboratory tests ware aimed at evaluating the thermal treatment modification effect on the cast steels properties. A significant role of the morphology of ledeburitic cementite and secondary cementite on the tribological properties was exhibited. The investigations assumed the presence of an austenitic matrix with primary and secondary cementite. Influence of varying morphology carbides was described. in the cast steel microstructure. The investigation results make possible to point to a direction of carbide morphology change with the purpose of obtaining the assumed properties of hot operation tools. [ABSTRACT FROM AUTHOR]

Ni-W/ZrO 2 nanocomposite coatings were synthesised by electrochemical deposition from an aqueous sulphate-citrate electroplating solution containing zirconia nanoparticles in suspension. The electrodeposition process was carried out under a galvanostatic regime and controlled hydrodynamic conditions (in a rotating disc electrode system). The main aim of the study was to optimise the process parameters for the electrodeposition of Ni–W coatings modified by ZrO 2 particles. Based on the results of previously conducted research, the set of experiments (eight series) was designed. The relationship between chemical composition, microstructure, and mechanical, wear and corrosion properties of Ni-W/ZrO 2 nanocomposites, along with the electrodeposition parameters such as content of ZrO 2 powder suspended in the galvanic bath, cathodic current density, hydrodynamic conditions and, ultrasonic field frequency were studied. Within the range of the experiments, the preferred combination of process parameters was determined to be zirconia nanoparticle content in the plating bath of about 5 g/L, ultrasonic (35 kHz) DC electrodeposition with current density of 11 A/dm 2 , applied cathode rotating rate of 600 rpm, yielding hardness, wear and corrosion rates of about 8 GPa and 1.4·10 −6  mm 3 /Nm and 6 μA/cm 2 , respectively. [ABSTRACT FROM AUTHOR]

Recently, to reduce the residual stress and increase the mechanical properties of a-C:H coatings, metallic nanoparticles have been implanted into their structure. In the present work, to improve the properties of the coating, metallic nanoparticles, including Cu, Nb, Ta, Zr, AgPt and Ag, were inserted into the a-C:H structure. The applied biological and mechanical analysis allowed the optimal biotribological parameters to be indicated for the potential application as protective coatings for metallic medical tools. Wear mechanisms operating at the small length of the designed biotribological coating, such as a-C:H implanted by Zr nanoparticles, were studied by means of transmission electron microscopy (TEM). The TEM analysis confirmed very good coating adhesion to the metallic substrate. [ABSTRACT FROM AUTHOR]

In this work, nanocomposite HA/chitosan coatings were electrophoretically deposited (EPD) on a near-β Ti-13Nb-13Zr alloy. The influence of the state of the HA particles introduced to the colloidal solution of chitosan (nc-HA-p as a nanopowder and nc-HA-s as nanoparticles suspended in ethanol), as well as the chemical composition of a multi-component HA-chitosan suspension and EPD parameters, on the homogeneity of coatings has been studied. It was established that the pH value and the chemical composition of the suspension have a substantial effect on the electrokinetic properties of suspended HA and chitosan particles. These are also influenced by the deposition kinetics of EPD and the uniformity of as-deposited coatings. The thickness of the nc-HA-p/chitosan and nc-HA-s/chitosan coatings was up to 750 nm and 1.5 μm, respectively. The nc-HA-s/chitosan coating microstructure consisted of HA nanoparticles, homogeneously embedded in an amorphous chitosan matrix. The nc-HA-p/chitosan coating microstructure was non-homogeneous, composed of HA agglomerates in a chitosan matrix. The presence of thin oxide layer was observed on the coatings/titanium alloy interface. The nc-HA-s/chitosan coating exhibited better adhesion to the titanium alloy substrate than the nc-HA-p/chitosan coating. It was found that the nc-HA-s/chitosan coating improves the electrochemical corrosion resistance of the Ti-13Nb-13Zr alloy in Ringer's solution, as well as its bioactivity and other biological properties. [ABSTRACT FROM AUTHOR]

Porous hydroxyapatite doped SiO2 coatings were electrophoretically deposited (EPD) on commercially pure titanium. The influence of EPD parameters on coatings quality was investigated. Microstructural observation was done using transmission and scanning electron microscopy as well as X-ray diffractometry. The coatings consisted of spherical micro and nanocrystalline hydroxyapatite (HAp) as well as amorphous SiO2 nanoparticles. The coatings exhibited open porosity with pore diameter up to 1 μm and due to presence of nanoparticles high surface development. It was found that application of SiO2/HAp coating increase corrosion resistance of titanium in Ringer's solution. [ABSTRACT FROM AUTHOR]

Ni-W/ZrO 2 nanocomposite coatings were electrodeposited in a system with a rotating disk electrode (RDE), which ensures constant and controlled hydrodynamic conditions. The influence of solution chemistry on the co-discharge kinetics of W(VI) and Ni(II) species from citrate solution have been studied. It was found that in the range of less negative cathode potentials both partial processes (deposition of tungsten and nickel) are controlled by charge transfer reaction, whereas with further increase of the cathodic polarisation the W(VI) electroreduction process becomes diffusion controlled. The addition of ceramic particles to the alloy plating bath changes cathodic polarisation, and thus chemical composition of the deposited Ni-W matrix. The effect of rotating rate of the steel RDE on the chemical composition and homogeneity of embedded zirconia nanoparticles in the Ni-W alloy matrix was investigated. The optimal hydrodynamic conditions for electrodeposition of homogeneous Ni-W/ZrO 2 nanocomposites with enhanced functional properties were determined based on microstructural (morphology, phase composition, crystallite size), micromechanical (microhardness, Young's modulus), and tribological (wear resistant, friction coefficient) properties. The maximum incorporation of ZrO 2 nanoparticles (about 4.5 wt%) was achieved at the disk cathode rotation speed of 300 rpm. Ni-W/ZrO 2 coatings obtained in such hydrodynamic conditions were characterized by the highest hardness (9.1 GPa) and Young's modulus (205 GPa), but due to the significant brittleness revealed the lowest wear resistance. [ABSTRACT FROM AUTHOR]

Studies of advanced protective chromium-based coatings on the carbon fibre composite (CFC) were performed. Multidisciplinary examinations were carried out comprising: microstructure transmission electron microscopy (TEM, HREM) studies, micromechanical analysis and wear resistance. Coatings were prepared using a magnetron sputtering technique with application of high-purity chromium and carbon (graphite) targets deposited on the CFC substrate. Selection of the CFC for surface modification in respect to irregularities on the surface making the CFC surface more smooth was performed. Deposited coatings consisted of two parts. The inner part was responsible for the residual stress compensation and cracking initiation as well as resistance at elevated temperatures occurring namely during surgical tools sterilization process. The outer part was responsible for wear resistance properties and biocompatibility. Experimental studies revealed that irregularities on the substrate surface had a negative influence on the crystallites growth direction. Chromium implanted into the a-C:H structure reacted with carbon forming the cubic nanocrystal chromium carbides of the Cr23C6 type. The cracking was initiated at the coating/substrate interface and the energy of brittle cracking was reduced because of the plastic deformation at each Cr interlayer interface. The wear mechanism and cracking process was described in micro- and nanoscale by means of transmission electron microscope studies. Examined materials of coated CFC type would find applications in advanced surgical tools. [ABSTRACT FROM AUTHOR]

Ni–W/ZrO 2 nanocomposite coatings were electrodeposited on steel substrates in a system with a rotating disk electrode (RDE). The effect of current density of the plating process on the chemical composition, microstructure and physicochemical properties of resulting composites was studied. Based on microstructural (morphology, phase composition, crystallite size), micromechanical (microhardness, Young's modulus), tribological (wear resistant, friction coefficient) and corrosion (corrosion potential, corrosion current density) properties, the optimal direct current (DC) density range for electrodeposition of homogeneous Ni–W/ZrO 2 nanocomposites with enhanced functional properties was determined. [ABSTRACT FROM AUTHOR]