Variability in the proliferative responsiveness of cultured human vascular smooth muscle cells to alpha-thrombin

alpha-Thrombin, a key enzyme of the coagulation cascade, is also a potent mitogen for many cell types. In the present study, the responsiveness to alpha-thrombin of cultured human vascular smooth muscle cells (HVSMC) derived from either vein or normal and atherosclerotic arteries was investigated. All HVSMC populations examined responded mitogenically to alpha-thrombin. However, the extent of this response varied between different cell populations. No significant differences were observed between HVSMC derived from vein versus artery or atherosclerotic versus normal tissues. The responsiveness of a specific HVSMC culture to alpha-thrombin was not affected by cell density and remained constant over several passages. Unlike platelet-derived growth factor BB (PDGF-BB), alpha-thrombin did not exhibit any significant chemotactic effects on HVSMC or induce their anchorage independent growth in semi-solid medium. The hypothesis that the observed variability in HVSMC responsiveness to alpha-thrombin is due to the heterogeneity of cultured HVSMC is raised and discussed.     

Ab Initio and Monte Carlo Approaches for the Magnetocaloric Effect in BaMnO<Subscript>3</Subscript> Oxide Perovskite

The self-consistent ab initio calculations, based on density functional theory approach (DFT) and using full potential linearised augmented plane wave (FLAPW) method, have been used to investigate both electronic and magnetic properties of the BaMnO₃ perovskite. Spin-polarised calculations, including the spin-orbit interaction, are used to determine the energy of the ferromagnetic (FM) and antiferromagnetic (AFM) states of BaMnO₃ perovskite. Obtained data from ab initio calculations are used as input for the Monte Carlo simulations to compute other magnetic parameters. Magnetisation, specific heat and magnetic entropy change have been given using the Monte Carlo simulations. The adiabatic temperature change, transition temperature and relative cooling power have been established.     

Study of the Role of the Tyrosine Kinase Receptor MerTK in the Development of Kidney Ischemia-Reperfusion Injury in RCS Rats

Renal ischaemia reperfusion (I/R) triggers a cascade of events including oxidative stress, apoptotic body and microparticle (MP) formation as well as an acute inflammatory process that may contribute to organ failure. Macrophages are recruited to phagocytose cell debris and MPs. The tyrosine kinase receptor MerTK is a major player in the phagocytosis process. Experimental models of renal I/R events are of major importance for identifying I/R key players and for elaborating novel therapeutical approaches. A major aim of our study was to investigate possible involvement of MerTK in renal I/R. We performed our study on both natural mutant rats for MerTK (referred to as RCS) and on wild type rats referred to as WT. I/R was established by of bilateral clamping of the renal pedicles for 30′ followed by three days of reperfusion. Plasma samples were analysed for creatinine, aspartate aminotransferase (ASAT), lactate dehydrogenase (LDH), kidney injury molecule -1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) levels and for MPs. Kidney tissue damage and CD68-positive cell requirement were analysed by histochemistry. monocyte chemoattractant protein-1 (MCP-1), myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS), and histone 3A (H3A) levels in kidney tissue lysates were analysed by western blotting. The phagocytic activity of blood-isolated monocytes collected from RCS or WT towards annexin-V positive bodies derived from cultured renal cell was assessed by fluorescence-activated single cell sorting (FACS) and confocal microscopy analyses. The renal I/R model for RCS rat described for the first time here paves the way for further investigations of MerTK-dependent events in renal tissue injury and repair mechanisms.     

Synergistic corrosion inhibition study of Armco iron in sodium chloride by piperidin-1-yl-phosphonic acid-Zn system

Electrochemical techniques, weight loss method and surface analysis were used to study the synergistic inhibition offered by Zn²⁺ and piperidin-1-yl-phosphonic acid (PPA) to the corrosion of Armco iron in 3% chloride solution. It is observed that the combination between PPA and Zn²⁺ shows excellent inhibition efficiency. The potentiodynamic polarization curves reveal that 5 × 10⁻³ mol l⁻¹ of PPA has only 76.7% inhibition efficiency whereas the mixture containing 5 × 10⁻³ mol l⁻¹ PPA -20%Zn²⁺ has 90.2% inhibition efficiency. This suggests that a synergistic effect exists between Zn²⁺ and PPA. The Fourier transform infrared (FTIR) spectrum of the film formed on iron indicates phosphonates zinc salt formation. A suitable mechanism of corrosion inhibition is proposed based on the results obtained. The surface film analysis showed that in the absence of Zn²⁺, the protective film consists of Fe²⁺-PPA complex formed on the anodic sites of the metal surface, whereas in the presence of Zn²⁺, the protective film consists of Fe²⁺-PPA complex and Zn(OH)₂.     

First Principle Calculations and Monte Carlo Simulations Investigation of Structural,Electronic, Magnetic,Elastic and Thermoelectric Properties of Antiperovskites $$Mn_3ZnX (\mathrm{X}= \mathrm{C, \ N})$$ M n 3 Z n X ( X = C,N )

Journal of Superconductivity and Novel Magnetism - The structural, electronic, magnetic elastic and thermoelectric properties of $$Mn_3ZnX$$ (X = N,C) have been investigated in the framework of...     

Corrosion inhibition of Armco iron by 2-mercaptobenzimidazole in sodium chloride 3% media

The effect of 2-mercaptobenzimidazole (2MBI) on the corrosion of Armco iron in NaCl media has been investigated in relation to the concentration of the inhibitor by various corrosion monitoring techniques. Surface morphology was studied by scanning electron microscopy (SEM). Results obtained revealed that 2MBI is a good anodic inhibitor. The addition of increasing concentrations of 2MBI moves the corrosion potential towards positive values and reduces the corrosion rate. EIS results show that the changes in the impedance parameters (R_t and C_dl) with concentrations of 2MBI is indicative of the adsorption of these molecules leading to the formation of a protective layer on iron surface. The adsorption of this compound is also found to obey Langmuir’s adsorption isotherm in NaCl.     

Study of Magnetic Properties in Spinels Co x Zn1?x Cr2O4 systems

The exchange interactions J _AA(x) and J _AB(x) are calculated by using a probability law for the Co _x Zn_1?x Cr₂O₄. The magnetic properties of a diluted ferromagnetic spinels Co _x Zn_1?x Cr₂O₄ system are investigated by using the high-temperature series expansions combined with the Padé approximants. The magnetic phase diagram, i.e., T _N versus?x, and the critical exponent associated with the magnetic susceptibility (??) are deduced.     

Study of the Magnetic Properties of the Zn-Doped Spinel LiV2O4 Materials

The magnetic properties of spinel Zn _x Li_1?x V₂O₄ systems are studied by using the probability law, and high-temperature series expansions in the range 0≤x≤1. The nearest-neighboring J ₁(x) and the next-neighboring super-exchange J ₂(x) interactions are obtained. The intra-planar and the inter-planar exchange interaction are obtained. The corresponding classical exchange energy for the magnetic structure is obtained. The high-temperature series expansion combined with the Padé approximants method has been applied to the spinel Zn _x Li_1?x V₂O₄ systems to determine the magnetic phase diagram. The critical exponents associated with the magnetic susceptibility γ and with the correlation lengths ν are deduced.     

Study of the Magnetic Properties of the Zn-Doped Spinel CdV2O4 Materials

The magnetic properties of spinel Cd_1?x Zn _x V₂O₄ systems in the range 0≤x≤1 are studied by mean field theory and high-temperature series expansions (HTSE). The nearest neighboring and the next-neighboring superexchange interactions J ₂(x) and J ₂(x) are given. The intra-planar and the inter-planar interaction are deduced. The HTSE theory is applied in the spinel Cd_1?x Zn _x V₂O₄ systems, combined with the Padé approximants method, to determine the magnetic phase diagrams (T _N versus dilution x) in the range 0≤x≤1. The critical exponents associated with the magnetic susceptibility γ and the correlation lengths ν are deduced.     

A time semi-exponentially fitted scheme for chemotaxis-growth models

In this work, we develop a new linearized implicit finite volume method for chemotaxis-growth models. First, we derive the scheme for a simplified chemotaxis model arising in embryology. The model consists of two coupled nonlinear PDEs: parabolic convection-diffusion equation with a logistic source term for the cell-density, and an elliptic reaction-diffusion equation for the chemical signal. The numerical approximation makes use of a standard finite volume scheme in space with a special treatment for the convection-diffusion fluxes which are approximated by the classical Il’in fluxes. For the time discretization, we introduce our linearized semi-exponentially fitted scheme. The paper gives a comparison between the proposed scheme and different versions of linearized backward Euler schemes. The existence and uniqueness of a numerical solution to the scheme and its convergence to a weak solution of the studied system are proved. In the last section, we present some numerical tests to show the performance of our method. Our numerical approach is then applied to a chemotaxis-growth model describing bacterial pattern formation.