Structural levels of fatigue failure and damage estimation in 17Mn1Si steel on the basis of a multilevel approach of physical mesomechanics

The evaluation of crack initiation and growth at microscopic scale is a crucial issue for the safety assessment of macroscopical fractures. In the present paper, the crack propagation in 17Mn1Si steel macroscale is investigated by taking into account the microstructural damage accumulation in polycrystalline solids. The revealed regularities are in good agreement with the concept of physical mesomechanics, which allows obtaining a generalized view of the material deformation and the failure process in the vicinity of the concentrator, which fulfills the limiting, initial and physical conditions and allows obtaining the generalized regularities in deformation and failure of 17Mn1Si steel.     

Diminazene Aceturate Stabilizes Atherosclerotic Plaque and Attenuates Hepatic Steatosis in apoE-Knockout Mice by Influencing Macrophages Polarization and Taurine Biosynthesis

Atherosclerosis and nonalcoholic fatty liver disease are leading causes of morbidity and mortality in the Western countries. The renin–angiotensin system (RAS) with its two main opposing effectors, i.e., angiotensin II (Ang II) and Ang-(1–7), is widely recognized as a major regulator of cardiovascular function and body metabolic processes. Angiotensin-converting enzyme 2 (ACE2) by breaking-down Ang II forms Ang-(1–7) and thus favors Ang-(1–7) actions. Therefore, the aim of our study was to comprehensively evaluate the influence of prolonged treatment with ACE2 activator, diminazene aceturate (DIZE) on the development of atherosclerotic lesions and hepatic steatosis in apoE^−/− mice fed a high-fat diet (HFD). We have shown that DIZE stabilized atherosclerotic lesions and attenuated hepatic steatosis in apoE^−/− mice fed an HFD. Such effects were associated with decreased total macrophages content and increased α-smooth muscle actin levels in atherosclerotic plaques. Moreover, DIZE changed polarization of macrophages towards increased amount of anti-inflammatory M2 macrophages in the atherosclerotic lesions. Interestingly, the anti-steatotic action of DIZE in the liver was related to the elevated levels of HDL in the plasma, decreased levels of triglycerides, and increased biosynthesis and concentration of taurine in the liver of apoE^−/− mice. However, exact molecular mechanisms of both anti-atherosclerotic and anti-steatotic actions of DIZE require further investigations.     

Determination of total cysteamine in human serum by a high-performance liquid chromatography with fluorescence detection

A convenient, reliable and rapid method for determination of total cysteamine in human plasma by high-performance liquid chromatography with fluorescence detection is reported. This assay involves reduction of samples with dithiothreitol, derivatization of total cysteamine by addition of monobromobimane and protein precipitation by perchloric acid. The calibration curve was linear in the range 2-150 nmol ml-1 and the detection limit was 0.5 nmol ml-1. This method was successfully applied for a pharmacokinetic study of three cysteamine derivatives in healthy volunteers without any interference from coexisting substances.     

Diagnostics and modeling of an argon/helium plasma spray process

The natural instability of the are in direct current (DC) plasma torches used in spray processing is one of the most important causes for variations in heating of sprayed particles, leading to inconsistencies in the final coating quality. A relatively simple diagnostic system has been set up to monitor the plasma jet instability, as well as some important process characteristics. Effects of the operating parameters and the anode condition on properties of plasma jets, particle properties, and coatings have been measured. These results show that the inconsistency caused by the jet instability influences the plasma spray process in several ways. The coating porosity and the deposition efficiency can be correlated to an average jet length obtained from a series of high speed images. Selected frequency peaks in the power spectrum of the acoustic signal are correlated with the average jet length, and these results are used to derive a simple control scheme, which adopts a fuzzy look-up model indicating the condition of the anode. Increasing the are current is the most effective way to counteract the negative effects of anode erosion.     

Effect of bisphosphonates (HEBP, CL2MBP) on the process of biological mineralization in fresh bone and bone tissue de novo as a result of experimental osteogenesis induction in guinea pigs

It is known from the literature that bisphosphonates inhibit mineralization process in skeletal tissues. To study in vivo the effects of HEBP (etidronate) and Cl2MBP (clodronate) both on preexisting bone mineral as well as on the early stages of the mineralization process the experimental model of heterotopical bone induction was chosen. Urinary bladder mucosa was used as an inductor of osteogenesis. Using this model it is possible to compare the effects of bisphosphonates on preexisting mineral on ortothopic bones as well as on the early stages of mineral deposition in the newly formed bone induced in heterotopic sites. HEBP and Cl2MBP doesn't inhibit heterotopic bone induction, but HEBP deeply inhibits the mineralization process; the small amount of deposited mineral does not contain crystalline fraction.     

On the connection between microstructure and surface roughness of brass sheets and their formability

The aim of this work was the analysis of the relationships between material properties and forming limits of a sheet, caused by the strain localization in the groove. In particular, we aim at the replacement of a nonmeasurable inhomogeneity coefficient of the material, the value of which has to be taken a priori, by measurable coefficients. In the proposed model, it is assumed that the material heterogeneity is a result of surface roughness and presence of internal defects (voids). The value of inhomogeneity coefficients changes with increasing strain. The experiments were carried out for M85 brass sheets, annealed to produce different microstructures. The measured values of some material parameters: strain-hardening constants n and C, normal anisotropy factors, inhomogeneity coefficients (surface roughness and volume fraction of voids) as well as forming limit curve demonstrated their dependence on the grain size. As a result of the experimental work, original equations were proposed, describing the relationship between inhomogeneity coefficients and effective strain and grain size. These equations were used in the theoretical calculation of the forming limit diagram. The theoretical calculations of the strain limits of the tested sheets were based on the associated flow rules, assuming strain-hardening and strain-softening process (Shima–Oyane equation and equations based on the Gurson theory). The analysis of the influence of different material parameters on the forming limit diagram has shown that in the case of the material tested, the value of limit strains depends decisively on the values of the inhomogeneity coefficients and grain size. The postulates showing proportional relationship between the value of a strain-hardening exponent and limit strains were not confirmed.     

Synthesis of Novel Pyrido[1,2-c]pyrimidine Derivatives with 6-Fluoro-3-(4-piperidynyl)-1,2-benzisoxazole Moiety as Potential SSRI and 5-HT1A Receptor Ligands

Two series of novel 4-aryl-2H-pyrido[1,2-c]pyrimidine (6a–i) and 4-aryl-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine (7a–i) derivatives were synthesized. The chemical structures of the new compounds were confirmed by ¹H and ¹³C NMR spectroscopy and ESI-HRMS spectrometry. The affinities of all compounds for the 5-HT_1A receptor and serotonin transporter protein (SERT) were determined by in vitro radioligand binding assays. The test compounds demonstrated very high binding affinities for the 5-HT_1A receptor of all derivatives in the series (6a–i and 7a–i) and generally low binding affinities for the SERT protein, with the exception of compounds 6a and 7g. Extended affinity tests for the receptors D₂, 5-HT_2A, 5-HT₆ and 5-HT₇ were conducted with regard to selected compounds (6a, 7g, 6d and 7i). All four compounds demonstrated very high affinities for the D₂ and 5-HT_2A receptors. Compounds 6a and 7g also had high affinities for 5-HT₇, while 6d and 7i held moderate affinities for this receptor. Compounds 6a and 7g were also tested in vivo to identify their functional activity profiles with regard to the 5-HT_1A receptor, with 6a demonstrating the activity profile of a presynaptic agonist. Metabolic stability tests were also conducted for 6a and 6d.     

Contribution of dissolved cadmium to the viscosity of its solutions in molten cadmium chloride, bromide and iodide

Viscosity coefficient of molten Cd---CdX₂ (X---Cl, Br and I) systems as a function of the mole fraction of dissolved cadmium have been measured at temperatures between 903 K and 1.2 T^s_f, where T^s_f is the melting point of the particular salt solvent. The influence of dissolved metal on the viscosities of these salts has been correlated with the free volumes of the salt solvent. The calculated radii of the supposed flow units were found to be closer to the radius of Cd⁰ than that of Cd²⁺₂.According to the Cohen and Turnbull theory the temperature dependences of electrical conductivity and of viscosity of the molten cadmium halides lead to the radii of the electrical and viscosity transport units in these salts close to those of the corresponding anions.     

梅塞斯米特Bf-109 G-6

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