Model-based prognosis for intergranular corrosion

Among the advantages of Aluminium-based alloys for structural use is their corrosion resistance. However, while Aluminium alloys are highly resistant to uniform (general) corrosion, they are much more susceptible to types of localised corrosion, especially intergranular corrosion, which is a localised attack along the grain boundaries which leaves the grains themselves largely unaffected. In order to estimate the progress of such corrosion in a given sample, it is considered possible to generate a numerical model of some sort. While there has been much effort spent in the development of electrochemistry-based models, the use of grey and black-box models remains largely unexplored. One exception to this is the use of Cellular Automata (CA) models which have recently been exploited to model the progression of uniform corrosion. The object of the current paper is to apply the CA methodology to the case of intergranular corrosion. The first phase of the work has been concerned with generating appropriate CA rules which can qualitatively reproduce observed physics, and this work is reported here. A model is proposed which shows qualitative agreement with experimental data on the advance of the corrosion front

Effective surface dilatational viscosity of highly concentrated particle-laden interfaces

The effective surface dilatational viscosity is calculated of a flat interface separating two immiscible fluids laden with half-immersed monodisperse rigid spherical non-Brownian particles in the limit of high particle concentration. The derivation is based upon the facts that (i) highly concentrated particle arrays in a plane form a hexagonal structure and (ii) the dominant contribution to the viscous dissipation rate arises in the thin gaps between neighboring particles

Role of three-body interactions in formation of bulk viscosity in liquid argon

With the aim of locating the origin of discrepancy between experimental and computer simulation results on bulk viscosity of liquid argon, a molecular dynamic simulation of argon interacting via ab initio pair potential and triple-dipole three-body potential has been undertaken. Bulk viscosity, obtained using Green-Kubo formula, is different from the values obtained from modeling argon using Lennard-Jones potential, the former being closer to the experimental data. The conclusion is made that many-body inter-atomic interaction plays a significant role in formation of bulk viscosity.Comment: 4 pages, 3 figure

Properties of the H-bond network for two-dimensional lattice water model

A microscopic Hamiltonian of the hydrogen-bond network in two-dimensional lattice water is proposed, which describes the formation and disruption of the H bonds, their bending, and which satisfies the Bernal–Fowler rules [J. D. Bernal and R. H. Fowler, J. Chem. Phys. 1, 515 1933]. The thermodynamic properties of the H-bond network are studied using the method of many-particle irreducible distribution functions, which is a generalization of the Kikuchi cluster approach [R. Kikuchi, Phys. Rev. 81, 988 1951] and the Bethe–Peierls quasiactivities method [H. A. Bethe, Prog. R. Soc. A 150, 552 1935]. The temperature dependencies of the average number of H bonds per molecules, the contribution of the H bonds into the heat capacity of the system, and the parameters describing the correlations between the states of molecules on the neighboring sites are investigated. It is shown that depending on the magnitude of the interaction between the H bonds in the H-bond subsystem either smooth or sharp first-order phase transition can occur. The role of different factors in the formation of the properties of the H-bond network is discussed

Temperature dependence of density, thermal expansion coefficient and shear viscosity of supercooled glycerol as a reflection of its structure

The relationship of the microstructure of supercooled, highly viscous glycerol to the temperature dependence of its density, thermal expansion coefficient, and shear viscosity are discussed. The character of this temperature dependence at the transition from low viscosity state to the solid amorphous state solidified state without nuclei is described with help of function psi, which can be interpreted as the effective number of degrees of freedom responsible for the change of viscosity of glycerol over a broad range; these degrees of freedom are those related to the alpha-relaxation process. It is shown that the change in effective activation energy of the viscosity is completely determined by the parameter psi. The change in the shear viscosity of glycerol due to the influence of the solid-phase nuclei is considered. It is shown that the introduction of the parameter phi, equal to the specific volume occupied by the nuclei of the solid phase, together with psi provides a natural explanation of the temperature dependence of density and thermal expansion coefficients of glycerol in its liquid, solid amorphous, glassy, and crystal states. The peculiarities of the temperature dependence of phi(T) and psi(T) for glycerol and o-terphenyl are compared

Correlation between miR-146a and miR-155 levels and concentration of cytokines in patients with allergopathy in chronic persistence of Epstein-Barr virus infection

Analysis of correlation between miR-146a and miR-155 levels and concentration of antiviral cytokines in patients with allergopathy in active and latent phases of chronic persistence of Epstein-Barr virus infection (EBV) has been conducted. Thus, 38 patients with allergopathy and chronic persistence of EBV of different genders, age 32.73.2 years have been examined, who were divided into groups depending on the phases of virus persistence. Control group included 20 healthy individuals. Reliable changes in IL12, IL33, IL1ß and IFN- were revealed in patients of both groups. The results: reliably higher levels of miR-146a expression, by 2.9 times (р=8.0E-04) and by 2.25 times (р=0.011), respectively, compared with control group; reliable difference in miR-155 levels in patients with EBV-infection in active and latent forms of virus persistence (р=1.0E-07) and significant decrease in the indicated miRNA (р=1.0E-07) by 55.8 times in patients with latent course of EBV-infection compared with control. A reliable reverse correlation of various intensities was detected between IL12, IL1ß, IFN- and miR-146a; absence of correlation between TNF-α, IL33 and miR-146a was observed. A direct correlation was revealed between all investigated cytokines IL12, TNF-α, IL33, IL1ß, IFN- and miR-155. the results of investigation showed that elevation of miR-146a can prognostically indicate inhibition of pro-inflammatory activity of cytokines and anti-inflammatory protection with the formation of pathological disorders, including allergopathy. Meanwhile, the presence of chronic persistence of EBV demonstrates an opposite direction of correlations between miR-155 and cytokines with pro-inflammatory properties, which confirms the ability of opportunistic infections to modulate immune response toward allergopathy

Saddle-splay modulus of a particle-laden fluid interface

The scaled-particle theory equation of state for the two-dimensional hard-disk fluid on a curved surface is proposed and used to determine the saddle-splay modulus of a particle-laden fluid interface. The resulting contribution to saddle-splay modulus, which is caused by thermal motion of the adsorbed particles, is comparable in magnitude with the saddle-splay modulus of a simple fluid interface.Comment: 10 pages, 2 figure

Chronic gastritis and functional dyspepsia. Unity and struggle of two opposites

The review article describes the epidemiology, clinical picture, pathogenesis, approaches to the diagnosis and treatment of chronic gastritis and functional dyspepsia. Chronic gastritis is an unreasonably common diagnosis in our clinical practice, which is diagnosed in patients with disturbing dyspeptic complaints. According to the agreement documents, chronic gastritis is primarily a morphological concept. Chronic gastritis has no pathognomonic clinical signs and should be diagnosed during the histological examination of the gastric mucosa. Functional dyspepsia is a diagnosis that reflects the presence of a certain symptom complex (pain  or burning sensation in  the  epigastrium, a  feeling of  fullness or early satiety) in  the  absence of  diseases that could explain the symptoms. Secondary dyspepsia is diagnosed in patients with organic diseases of the upper gastrointestinal tract, metabolic or systemic diseases that cause dyspeptic syndrome. In the process of examining a patient with disturbing dyspeptic complaints, it is advisable for the doctor to use the diagnosis “unspecified dyspepsia” – a preliminary diagnosis before laboratory and instrumental examination aimed at identifying the cause of the dyspeptic syndrome. Dyspepsia associated with H. pylori is diagnosed in patients with H. pylori infection. The diagnosis is revised over time and is competent if complaints have been relieved within 6 months after effective H. pylori eradication.The main drugs for the treatment of patients with dyspeptic complaints are proton pump inhibitors and prokinetics. Omeprazole with domperidone sustained release (SR) in a fixed dose combination is characterized by optimal efficacy and a good safety profile in patients with both functional and secondary dyspepsia and ensures a high level of treatment adherence

Effective surface shear viscosity of an incompressible particle-laden fluid interface

The presence of even a small amount of surfactant at the particle-laden fluid interface subjected to shear makes surface flow incompressible if the shear rate is small enough [T. M. Fischer et al., J. Fluid Mech. 558, 451 (2006)]. In the present paper the effective surface shear viscosity of a flat, low-concentration, particle-laden incompressible interface separating two immiscible fluids is calculated. The resulting value is found to be 7.6% larger than the value obtained without account for surface incompressibility