Search

Experimental studies of combustion stability to the local excess of the component in a dispersed mixture of titanium and carbon powder are presented. It is shown how the spreading of a melt of a low-melting or liquid reaction product affects the stability of combustion transition through a solid and perforated carbon powder target. The melt motion direction with respect to the front propagation direction is revealed. It is indicated that the stability of the combustion transition through the target is determined by thermal interaction between the combustion wave and the target and is not directly related to the convective heat transfer by the melt. [ABSTRACT FROM AUTHOR]

A list of the Crimean bird fauna is presented to reflect the current state of knowledge and to characterize the status and environmental specificity of the species involved. For the first time, an analysis of the phenological and ecological structure of the Crimean avifauna as a whole is carried out, separately for the mountain and plain parts which support various zoochorological subunits. The special position of foothills as an area transitional between the coastal zone and the forested steppe belt is shown. Based on the literature record and collections available for the territory of the peninsula during the entire period of research (1795–2019), 385 species of birds are listed, including nine found only as fossils. The present avifauna encompasses 320 species belonging to 53 families and 19 orders. Four orders (Passeriformes, Charadriiformes, Anseriformes, Falconiformes) comprise 254 species, or 78.6% of the Crimean avifauna, while the remaining orders contain from one to 13 species each. As regards the ecological structure, limnophiles (42.3%) and dendrophiles (34.5%) dominate, while campophiles account for 11.3%. In distribution, the largest number belong to the group of migrants (252 species, or 79% of the Crimean avifauna), including species the local populations of which are settled (20), nesting-migratory (82), and those arriving for wintering (69). For 197 species (61.8%), nesting has been reliably documented, and a further eight species can be classified as most probably nesting. There are 99 migrant species, of which 17 overwinter and five more do this sporadically. As many as 167 species (52.4%) have been recorded during the winter season, 58 of them being sedentary, 63 species regularly passing the winter, 42 rarely or sporadically doing so, and 31 species occurring only in winter. The summering group includes 45 species, most of which are northern migrants (Charadriiformes, 21, and Anseriformes, five), as well as western Palaearctic ones (four). At least 26 species, as well as probably a further 17, can be assigned to the group of "vagrant birds," while six species are classified as "nomadic birds." Features of the distribution of birds over the territory are revealed when comparing the avifauna of various zoochorological subunits. The bird species diversity is decreased both from the plain (97.5% of all fauna) to the mountainous (90.3%) areas of Crimea and from the foothills (89.9%) to the mountain forest belt (53.6%). Within the steppe zone, there are more migrants (242 vs. 218), nesting (159 vs. 128) and nesting-migratory (83 vs. 62) species than in the mountains. At the same time, most of the sedentary species have been recorded in the mountainous area: 31 vs. 18 on the plain. Migrations of birds due to diurnal and seasonal rhythms are known for at least 54 species, but only 23 of them roam the steppe, and 21 species are nomadic in the mountains. [ABSTRACT FROM AUTHOR]

A computational and experimental study of the passage of a gasless combustion wave through a wedge-shaped inert obstacle was performed. The stability of the transient combustion process to a change in the thermophysical and geometric parameters of the obstacle and the energy-kinetic parameters of chemically active layers was studied. By the region of stable transient combustion process is meant the range of parameters in which the passage of the combustion wave through the contact boundary ends with the establishment of its steady-state propagation regime in the ignited composition. The dynamics of transient combustion under near-critical conditions of its existence was investigated. [ABSTRACT FROM AUTHOR]

The transition of the combustion wave of a titanium powder layer in air through an inert shaped obstacle has been experimentally studied. It has been shown that an inhomogeneous wave-like structure of the combustion front can form due to the limited supply of gaseous reagents and the thermal instability of combustion of the titanium powder layer. Conditions of the optimal transient combustion mode in the presence of gaseous impurities affecting gas exchange in the reaction zone and the stability of the front in the layered system are obtained. It is shown that there exists a phenomenological criterion for assessing the nature of the transient combustion mode of titanium powder depending on the shape of the inert obstacle and the combustion front. [ABSTRACT FROM AUTHOR]

The formation and propagation of cellular combustion of porous media under near-critical combustion existence conditions were investigated. The sizes and structure of cells in which the condensed component reacted with the gas depended nonlinearly on the heat loss to the environment. With increasing heat loss, the oscillation frequency of the cellular front, its average propagation velocity, and the intensity of the exothermic transformation of the condensed phase increased, and the cell sizes decreased. Cellular combustion was extinguished only when the transformation of the condensed component within a cell was completed. [ABSTRACT FROM AUTHOR]

The paper describes the formation of the combustion zone structure of a titanium powder layer in inclined rectangular air channels with natural gas filtration. It is shown that heterogeneous combustion near the critical conditions of its existence with limited supply of gaseous reagent in the reaction zone and under the effect of gravitational forces is accompanied by rearrangement of the plane homogeneous front into more complex wave structures: cellular, cross-cellular, and heterogeneous. The features of the process under study is the presence of gaseous impurities affecting the gas exchange in the reaction zone, the destabilization of the plane front, and the formation and propagation of heterogeneous and cellular wave structures. [ABSTRACT FROM AUTHOR]

External manifestations of the heterogeneous combustion front are characterized. Gasdynamic aspects of the phenomenon are considered, and experimental data on the change of combustion modes during natural filtering of an air mixture are analyzed. Results of an investigation of the bifrontal structure of the combustion zone in a horizontal plane layer during convective gas transfer are presented. [ABSTRACT FROM AUTHOR]

The cellular filtration combustion of porous energetic compositions that interact with an active gas reagent and form condensed reaction products is studied for titanium powder combustion as an example. A simple and visually accessible quasi-experimental analysis of the nonlinear propagation of the combustion front with adjustable filtration transport of gas is proposed. Under conditions of a deficiency of the gas reagent and instability, the flat front of filtration combustion is divided into isolated cells of exothermic chemical reaction propagating in a pulsating mode. The results obtained are interpreted within a model of thermal filtration stability of the filtration combustion front. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the cellular modes of filtration combustion. It says that high-temperature synthesis of construction materials is conducted through filtration combustion of porous high energy compositions that interacts with an active gas reagent and forms condensed reaction products. The results show that the pulsing mode of cells motion of the exothermic chemical transformation was discovered for the first time.

The filtration combustion of a layered porous fill consisting of alternating layers of a mixture of Ti + 0.5C a titanium powder with forced concurrent filtration of nitrogen was studied for the first time. The gas flow through the sample was provided by a vacuum pump attached to the lower end of the fill. The presence of the concurrent gas flow radically changes the character of propagation of the combustion front and the structure and composition of the products obtained. The layers consisting of carbonitride and titanium nitride make a single unit. The experiments provided scientific bases for the production of new laminated and composite ceramic materials by dynamic filtration combustion. [ABSTRACT FROM AUTHOR]

Discusses an analytical method of calculation of the temporal characteristics of ignition of hybrid gas-solid suspensions by a heated body. Parameter ranges of the kinetically controlled and diffusion-controlled ignition modes; Effect of the heat release in gas-phase reactions on the temporal characteristics of ignition; Model of the process.

Abstract: Telocytes (TCs) are a recently identified type of interstitial cells present in a wide variety of organs in humans and mammals (www.telocytes.com). They are characterized by a small cell body, but extremely long cell processes – telopodes (Tp), and a specific phenotype. TCs establish close contacts with blood capillaries, nerve fibers and stem cells. We report here identification of TCs by electron microscopy and immunofluorescence in rat meninges and choroid plexus/subventricular zone, in the vicinity of putative stem cells. The presence of TCs in brain areas involved in adult neurogenesis might indicate that they have a role in modulation of neural stem cell fate. [Copyright &y& Elsevier]

The combustion of Ti-C mixtures of bulk density under inert gas blowing conditions produced by evacuation of one end of the reaction cell was studied for the first time. The experiments showed that the tested mixtures in quartz cups were not ignited and did not burn without the inert gas (argon) flow. Increasing the rate of gas evacuation from the sample increased the rate of steady-state combustion of the mixture of titanium with carbon black, and for the mixture of titanium with graphite, stabilization of the flat combustion front was observed. It is shown that the presence of small pressure difference (up to 105 Pa) allows control of the combustion process and confirms the basic postulates of the convective-conductive theory of combustion for heterogeneous condensed systems. [ABSTRACT FROM AUTHOR]

The specific features of dynamics of the thermal explosion in systems porous reagent- active gas-solid product under conditions where the heat-transfer and mass-transfer regions are separated from the ambient medium are considered. In addition to the competition of heat release and heat removal, the process of initiation of exothermal chemical interaction in these systems under normal pressures depends significantly on conditions of filtration transport of the gaseous reagent. The induction and post- induction periods of the thermal explosion are studied. The theoretical analysis of thermal-explosion issues is supplemented by an experimental study of the process for the porous titanium-nitrogen-titanium nitride system. [ABSTRACT FROM AUTHOR]

Purpose: Mutations in several sarcomeric Z-disc proteins, such as muscle LIM protein (MLP), have been shown to cause hypertrophic and dilated cardiomyopathies. The transcription factor MIP1 has been identified as a novel MLP interacting protein which is important in the cardiac stress response and able to cause cardiac hypertrophy in vivo. Here we examine, in vitro, the mechanisms behind this cardiac phenotype and investigate potential disease causing mutations in this protein.Methods and Results: Adenoviral overexpression of MIP1 in adult and neonatal rat cardiomyocytes (NRCMs) showed that MIP1 induces cardiac myocyte hypertrophy, as seen by increased cell size and real-time impedance measurements (n=10, p<0.01). MIP1-induced hypertrophy was significantly reduced by calcineurin inhibition by cyclosporine A (0.2μM; n=4, p<0.05). We also analyzed apoptotic events and impedance measurements after doxorubicin (1μM) treatment and found that MIP1 overexpression protects from apoptosis (n=7, p<0.05).A recent large Genome-wide Association Study suggested a role for genetic variation of MIP1 in disease susceptibility. We sequenced the human MIP1 gene in 916 unrelated individuals affected by cardiomyopathy and heart failure and identified three novel heterozygous variants (G179S, A188V, Q531R) and one that had been described previously (T106M). Adenoviral expression of all four mutants resulted in hypertrophy of NRCMs (n=5, p<0.01) and the mutant proteins were shown to be mislocalised in a proportion of adult cardiac myocytes (G179S 14.6%, A188V 22.6%, Q531R 25.7%) or not stably expressed (T106M). Hypertrophy induced by mutant MIP1 expression was not affected by calcineurin inhibition, indicating a different mechanism, and mutant MIP1 is not as efficient as the wild-type protein at protecting against doxorubicin-induced apoptosis (n=5, WT vs. -T106M p<0.05, -G179S p<0.05, -A188V p<0.01, -Q531R p<0.05).Conclusions: MIP1 regulates cardiac hypertrophy and cell survival, a recognized dual-property of genes of central importance for cardiac myocyte biology. The effects of MIP1 are dependent on calcineurin and mutations in MIP1 may be a potential cause of hypertrophic cardiomyopathy and heart failure. [ABSTRACT FROM AUTHOR]

Purposes: Mutations in sarcomeric proteins are a major cause of hereditary cardiomyopathies. Muscle LIM protein (MLP, CSRP3) is involved in cardiac mechanosensation and important for myocyte-specific survival pathways. Identification of novel MLP interacting proteins (MIP) may provide novel insights into underlying molecular mechanisms of human disease.Methods and Results: Yeast two-hybrid screens identified MIP1 as a novel MLP interacting protein, which is a member of the poxvirus and zinc-finger (POZ or BTB) domain/zinc-finger transcription factor family. The interaction was confirmed by co-immunoprecipitation, cross-linking of recombinant proteins and immunohistochemistry. Cardiac myocyte specific conditional knockout mice (cKO) were generated and underwent transverse aortic constriction (TAC) to unveil potential gene effects. After 4 weeks of TAC left ventricles of cKO mice became dilated (LVIDd mm: 3.74 vs 3.44, LVIDs mm: 2.00 vs 1.65, cKO: n=10, Control: n=8, P<0.01) and exhibited impaired contractile performance (FS %: 46.46 vs 52.01, cKO: n=10, Control: n=8, P<0.05). Failing cKO hearts had significantly higher apoptotic events (8.5-fold, n=6 per group, P<0.001), increased activated caspase 3 (6.3-fold, n=6 per group, P<0.001) and marked replacement fibrosis. To understand the molecular mechanisms by which MIP1 regulates cardiac myocyte survival we applied apoptosis gene-focused PCR array analysis combined with genome wide chromatin immunoprecipitation-chip (ChIP-chip). As a result, the expression of pro-apoptotic genes was increased in cKO hearts subjected to TAC (Gene Set Enrichment Analysis, P<0.05). Hence MIP1 regulates a transcriptional program that protects cells against apoptosis. To examine further the effects of MIP1 on hypertrophy we overexpressed MIP1 in mouse heart (TG). MIP1 TG mice exhibited spontaneous cardiac hypertrophy with enlarged cardiac myocytes (n=150 cardiac myocytes per animal; n=5 mice per group, P<0.001) and increased Anf expression (n=3, P<0.05). Moreover ChIP-chip data showed binding of MIP1 to the calcineurin Aβ promoter, confirmed by ChIP-qPCR (P<0.05) and luciferase reporter assays (P<0.01). These data are supported by increased mRNA expression of calcineurin Aβ and Nfatc2 in TG (n=3, P<0.05) and decreased expression in cKO animals after TAC. MIP1 TG/calcineurin Aβ deficient mice did not develop cardiac myocyte hypertrophy which provides proof for the hypothesis that MIP1 interferes with the calcineurin pathway.Conclusion: MIP1 plays a major role in the protection of cardiac myocytes from apoptosis through modulation of both hypertrophic and cell death pathways. [ABSTRACT FROM AUTHOR]

Despite optimal therapy, the morbidity and mortality of patients presenting with an acute myocardial infarction (MI) remain significant. Extracellular RNA (eRNA), exposed after cell damage, serves as cofactor for coagulation proteases and cytokines thereby promoting their procoagulant and proinflammatory functions in vivo. Following myocardial ischemia/reperfusion (I/R) in mice or I/R induced in the isolated Langendorff heart, increased eRNA levels were found together with cell injury markers. Likewise, eRNA was released from cardiomyocytes under hypoxia and subsequently induced tumor-necrosis-factor-a (TNF-α) liberation by activation of TNF-α converting enzyme (TACE) and provoked cardiomyocyte death. Conversely, TNF-a promoted eRNA release especially under hypoxia, feeding a vicious cell damaging cycle during I/R. Administration of RNase1 or TAPI (TACE-inhibitor) prevented cell death and myocardial infarction. Likewise, RNase1 significantly reduced I/R-mediated energy exhaustion, opening of mitochondrial permeability transition pores (mPTP) as well as oxidative damage in cardiomyocytes. Together, RNase1 as well as inhibition of TACE provide novel therapeutic regimen to interfere with the adverse eRNA-TNF-a interplay and significantly reduce or prevent the pathological outcome of ischemic heart injury. [ABSTRACT FROM PUBLISHER]

Abstract: We investigated the effect of pharmacological activation of the Ca2+-channel transient receptor potential cation channel, subfamily V, member 4 (TRPV4) on collateral growth in a pig hind limb-ischemia model thereby identifying subcellular mechanisms. Domestic pigs received femoral artery ligature and were randomly assigned to one of the following groups (each n =6): (1) 4α-phorbol 12,13-didecanoate (4αPDD) treatment; (2) treatment with an arterio-venous shunt (AV-shunt) distal to the occlusion; or (3) implantation of NaCl-filled minipump. Six sham-operated pigs acted as controls. Aortic and peripheral mean arterial pressure (MAP) measurements were performed to assess the collateral flow index (CFI). Tissue was isolated from M. quadriceps for immunohistochemistry and from isolated collateral arteries for quantitative real time PCR (qRT-PCR). Shortly after ligature the CFI dropped from 0.96±0.02 to 0.21±0.02 in all ligature-treated groups. In ligature-only-treated pigs CFI increased to 0.56±0.03 after 7days. Treatment with 4αPDD led to an enhancement of CFI compared with ligature alone (0.73±0.03). CD31-staining showed improved arteriolar density. Increased Ki67 staining in collaterals indicated proliferation. qRT-PCR and Western blot analysis showed upregulation or modulation of Ca2+-dependent transcription factors nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 1 (NFATc1), Kv channel interacting protein 3, calsenilin (KCNIP3/CSEN/DREAM), and myocyte enhancer factor 2C (MEF2C) in 4αPDD- and AV-shunt-treated pigs compared with controls. Improved CFI after 4αPDD treatment identifies TRPV4 as an initial fluid shear-stress sensor and collateral remodelling and growth trigger. Subcellularly, modulation of Ca2+-dependent transcription factors indicates a pivotal role for Ca2+-signalling during arteriogenesis. [Copyright &y& Elsevier]

An abstract of the study "Matrix Metalloproteinases and Inhibitors of Metalloproteinases in the Progression From Hypertrophy to Heart Failure," by V. Polyakova and S. Hein, is presented.

This article surveys and analyzes the literature data on nanotechnologies for copper and copper alloys. It describes the main methods used to obtain nanomaterials, including powder metallurgy, crystallization from the liquid state with a controlled rate of cooling, intensive plastic deformation, dispersion hardening, and dispersion strengthening with internal oxidation. Preference is given to nanophase materials in the discussion. [ABSTRACT FROM AUTHOR]

Objective: The objective of our study was to quantify the arteriogenic potency of Monocyte Chemoattractant Protein-1 (MCP-1) under hyperlipidemic conditions. Additionally, we aimed to determine the effects of locally applied MCP-1 on systemic serum lipid levels as well as on atherosclerosis. Methods: A total of sixty-four Watanabe rabbits was treated with either low dose MCP-1 (1 μg/kg/week), high dose MCP-1 (3.3 μg/kg/week) or PBS as a control substance. Substances were applied directly into the collateral circulation via an osmotic minipump with the catheter placed in the proximal stump of the ligated femoral artery. Either 1 week or 6 months after initiation of the treatment X-ray angiography was performed as well as measurements of collateral conductance using fluorescent microspheres. The extent of atherosclerosis was quantified in whole aortas using Sudan IV staining. Results: One week after ligation of the femoral artery a significant increase in collateral conductance was observed in animals treated with high dose MCP-1 (control: 2.2±0.8 ml/min/100 mmHg vs. MCP-1 high dose: 8.9±2.0 ml/min/100 mmHg, P<0.05). Six months after femoral artery ligation no differences were found between the treated and the control group (PBS; 44.9±11.6 ml/min/100 mmHg, MCP-1; 47.8±11.5 ml/min/100 mmHg, P=NS). No influence was found on serum lipids or on the development of atherosclerosis in the present model. Conclusion: MCP-1 accelerates arteriogenesis upon femoral artery ligation under hyperlipidemic conditions. Six months after treatment these pro-arteriogenic effects of MCP-1 can no longer be observed. The present data do not show an effect of local MCP-1 treatment on serum lipids or on atherosclerosis. It should be noted however that a high standard deviation was observed for the data on atherosclerotic surface area, necessitating additional experiments in a different model of atherosclerosis. [Copyright &y& Elsevier]

An abstract of the study "Bone Marrow Derived Stem Cells Are Not an Arterial Wall Constituting But Rather Supporting Cells During Collateral Vessel Growth in Mice," by T. Ziegelhoeffer and colleagues is presented.