Investigation of the influence of the mode of heat treatment of the initial powder on the efficiency of sintering zirconium ceramics by dilatometry

Using methods of synchronous thermal and X-ray structural analyzes applied to zirconium dioxide powders partially stabilized with yttrium obtained by chemical coprecipitation the processes of dehydration of these powders during annealing in air have been investigated. Using the dilatometry method, the regularities of compaction of powder compacts have been investigated with thermal sintering. It was found that the resulting powders mainly consist of the tetragonal modification zirconium dioxide and are nano-sized. The average particle size was 25 nm. The resulting powders are characterized by a high degree of agglomeration. It is shown that an increase in the thermal annealing temperature from 500 to 700ºС leads to partial baking of individual particles inside the agglomerate, and causes the formation of hard agglomerates, the presence of which complicates the processes of compaction and subsequent sintering. The presence of such agglomerates prevents the production of ceramics with high mechanical characteristics: density and porosity. Thermal annealing temperature increase leads to a decrease in the density of the sintered ceramic and a decrease in its hardness

Impact of glycolysis inhibitor (2-DG) and oxidation and phosphorylation uncoupler (2,4-DNP) on brain metabolites

Deviations in brain metabolism are the result of longterm pathological processes, which finally are manifested as symptoms of Parkinson’s or Alzheimer’s diseases or multiple sclerosis and other neuropathologies, as for example diabetic neuropathy. A deficiency of available energy for brain cells under neurodegenerative diseases is either developed due to age-dependent underexpression of genes that encode glycolytic enzymes or induced due to the uncoupling of oxidation and phosphorylation that could be mediated by inflammatory cytokines. Since the activity of many enzymes is under the control of adenosine triphosphate (ATP) or cofactors, such as nicotinamide adenine dinucleotide (NADH) and nicotinamide adenine dinucleotide phosphate (NADPH), energy deficiency can cause metabolic changes in brain tissue. Some clinical studies using proton nuclear magnetic resonance spectroscopy (1H NMR spectroscopy) revealed metabolic changes in brain tissue in patients with neurodegenerative diseases. However, data from different authors are quite contradictory, probably because of the complex genesis of metabolic disorders. In the present study, we tested the hypothesis of multidirectional changes in metabolism under the impact of the oxidation and phosphorylation uncoupler 2,4-dinitrophenol (2,4-DNP) and under the impact of 2-deoxy-Dglucose (2-DG), blocking the access of glucose to the brain cells. 1H NMR spectroscopy showed that 2-DG leads to the predominance of excitatory (glutamine + glutamate) neurotransmitters over inhibitory ones (gamma-aminobutyric acid), and 2,4 DNP causes opposite effects. The biochemical mechanisms of the observed changes require a special study, but it can be noted that the ATP deficiency caused by inhibition of glycolysis and the ATP deficiency caused by the uncouplers are accompanied by differently directed changes in the intensity of the tricarboxylic acid cycle. These changes in the intensity of the Krebs cycle are correlated with differently directed changes in the balance of the exciting and inhibitory neurotransmitters. The obtained results show that 1H NMR spectroscopy can be an effective method of differentiated lifetime assessment of the available energy deficit caused by a general suppression of energy exchange in nerve cells or oxidation and phosphorylation uncoupling

The human Rad9/Rad1/Hus1 damage sensor clamp interacts with DNA polymerase β and increases its DNA substrate utilisation efficiency: implications for DNA repair

In eukaryotic cells, checkpoints are activated in response to DNA damage. This requires the action of DNA damage sensors such as the Rad family proteins. The three human proteins Rad9, Rad1 and Hus1 form a heterotrimeric complex (called the 9-1-1 complex) that is recruited onto DNA upon damage. DNA damage also triggers the recruitment of DNA repair proteins at the lesion, including specialized DNA polymerases. In this work, we showed that the 9-1-1 complex can physically interact with DNA polymerase β in vitro. Functional analysis revealed that the 9-1-1 complex had a stimulatory effect on DNA polymerase β activity. However, the presence of 9-1-1 complex neither affected DNA polymerase λ, another X family DNA polymerase, nor the two replicative DNA polymerases α and δ. DNA polymerase β stimulation resulted from an increase in its affinity for the primer-template and the interaction with the 9-1-1 complex stimulated deoxyribonucleotides misincorporation by DNA polymerase β. In addition, the 9-1-1 complex enhanced DNA strand displacement synthesis by DNA polymerase β on a 1 nt gap DNA substrate. Our data raise the possibility that the 9-1-1 complex might attract DNA polymerase β to DNA damage sites, thus connecting directly checkpoints and DNA repai

Brain metabolites in ISIAH and Wistar rats

Hypertension is one of the most common human diseases. This disease leads to serious disturbances such as myocardial infarction and stroke. Due to the development of nuclear magnetic resonance spectroscopy (NMRS), a decrease in neuron viability in different parts of the brain in humans with hypertension has been shown. Translation of NMRS tools to the clinic requires the accumulation of empirical data about neurometabolic changes in a strictly controlled experiment. It is particularly interesting to compare the metabolic parameters of laboratory animals with normal and high blood pressure kept in standard conditions on exactly the same diet. In this study, cortex and hypothalamus metabolites of ISIAH and Wistar male rats at the age of 8–9 weeks were examined. Cortex and hypothalamus metabolites were measured in animals under isoflurane anesthesia using proton magnetic resonance spectroscopy (1Н MRS). Processing of primary data using Partial least squares Discriminant Analysis (PLS-DA) allowed us to identify the main discriminating axis (Y1), its variations reflecting the predominance of excitatory neurometabolites (glutamine and glutamate) over inhibitory ones (GABA and glycine). In the cortex, the values of the Y1-axis were lower in ISIAH than in Wistar rats. This fact indicates a decrease in cortical excitability in hypertensive animals. By contrast, in the hypothalamus, the values of the Y1-axis were higher in ISIAH than in Wistar rats and the predominance of excitatory neurometabolites positively correlated with the level of mean blood pressure, which agrees well with the view of caudal hypothalamic activation in hypertensive animal models

Radioluminescence properties of nanocomposite scintillators with BaF 2 fillers

In this paper, studies of the luminescence properties of nanocrystalline BaF 2 samples synthesized by laser ablation and pulse electron beam evaporation method are presented. The measurements of X-ray excited luminescence (XEL) showed the dependence between luminescence intensity and the shape of the spectrum on the morphology and particle size. Also, studies of X-ray excited luminescence, decay curves and optical transmittance for nanocomposite materials containing BaF 2 nanopowder are presented. Barium fluoride nanopowder, obtained by pulsed electron beam evaporation method is characterized by a lower intensity than the initial microcrystalline powder, but at the same time, XEL spectrum of the nanocomposite material with this nanocrystalline filler is more intense, then that for nanocomposite material with initial powder. © Published under licence by IOP Publishing Ltd

The effect of a single administration of streptozotocin on hippocampus metabolites in NODSCID mice

The significant increase in the number of people diagnosed with diabetes mellitus in recent years makes studies of this problem topical. The persistent hyperglycemia accompanying the development and course of type 1 diabetes mellitus (T1DM) can affect the func-tional and structural levels of the organization of the central nervous system. These changes may be medi­ated by metabolic aberrations. Magnetic resonance spectroscopy (MRS) is a common method of intravital detection of metabolic reactions. In this study, MRS of the hippocampus of NOD.CB17-Prkdcscid/NcrCrl mice (NODSCID) was performed 4 days after the administration of streptozotocin (STZ) to assess the effect of STZ itself, and 60 days after the administration of STZ to another group of animals to assess the effect of chronic hyperglycemia caused by the delayed ef­fect of STZ, involving the death of pancreatic β-cells. The simulation of T1DM by STZ administration is used worldwide. Nevertheless, the question remains whether there is a short-term effect of the introduc­tion of STZ at the level of hippocampal metabolites recorded by MRS. The comparison of experimental and control animal groups revealed no effect of STZ on metabolites in the hippocampus of NODSCID mice on day 4 after its administration. In contrast, another comparison of the experimental and control animals on day 60 after STZ administration showed elevated contents of alanine and taurine, and a reduced lactate content. Thus, the introduction of STZ itself does not affect the metabolism of the hippocampus, and MRS is a promising method for assessing the effect of T1DM on brain metabolism in animals

Синдром пароксизмальной симпатической гиперактивности (обзор)

Paroxysmal sympathetic hyperactivity (PSH) is one of the complications of acute severe brain injuries (traumatic brain injury, intracranial hemorrhage, ischemia, and posthypoxic conditions) in both adults and children. Its high incidence and severe sequelae including organ dysfunction, infectious complications, impaired blood supply to organs and tissues associate with increased disability and mortality. The choice of effective therapy can be challenging because of multifaceted manifestations, diagnostic difficulties, and lack of a clear understanding of the pathophysiology of PSH. Currently, there are various local and international treatment strategies for PSH.The aim of the review is to summarize clinical and scientific research data on diagnosis and treatment of PSH to aid in the selection of an effective therapy.Material and methods. Web of Science, Scopus and RSCI databases were employed to select 80 sources containing relevant clinical and research data on the subject of this review.Results. The key principles of diagnosis and treatment of paroxysmal sympathetic hyperactivity have been reviewed. The current views on etiology and pathogenesis of paroxysmal sympathetic hyperactivity development were outlined. The clinical data concerning complications and sequelae of paroxysmal sympathetic hyperactivity were analyzed. We conclude the review with a discussion of current methods of the syndrome prevention.Conclusion. Preventing PSH and its adequate and prompt treatment could help avoid the abnormal pathway development following a severe brain injury, reduce its negative consequences and rate of complications, along with the duration of mechanical lung ventilation, patient's stay in ICU, disability and mortality rates. Careful selection of pathogenetic, symptomatic and supportive therapy significantly improves the rehabilitation potential of patients.Одним из осложнений острого тяжелого повреждения мозга (черепно-мозговая травма, внутричерепные кровоизлияния, ишемия, постгипоксические состояния) как у взрослых, так и у детей является развитие синдрома пароксизмальной симпатической гиперактивности (ПСГА). Высокая частота его встречаемости и тяжелые негативные последствия: органная дисфункция, инфекционные осложнения, нарушения трофики органов и тканей, приводят к повышению инвалидизации и смертности. Сложности в подборе эффективной терапии связаны с многообразием симптомов, трудностями диагностики, отсутствием четкого понимания патофизиологии ПСГА. В настоящее время существуют различные зарубежные и отечественные схемы лечения ПСГА.Цель обзора — обобщить данные клинических и научных исследований по диагностике и лечению синдрома ПСГА для облегчения подбора эффективной терапии.Материал. В базах данных Web of Science, Scopus и РИНЦ отобрали 80 источников, содержавших актуальные данные клинических и научных исследований по теме данного обзора.Результаты. Рассмотрели основные принципы диагностики и лечения пароксизмальной симпатической гиперактивности; описали современные представления об этиологии и патогенезе развития пароксизмальной симпатической гиперактивности; привели клинические данные, касающиеся развития осложнений пароксизмальной симпатической гиперактивности; проанализировали клинические последствия и описали современные методы профилактики развития синдрома пароксизмальной симпатической гиперактивности.Заключение. Профилактика развития ПСГА, его адекватное и своевременное лечение позволяют предотвратить формирование патологической доминанты (мы рассматриваем ПСГА именно как одну из патологических доминант, формирующихся при тяжелом повреждении ГМ), уменьшить негативные последствия этого синдрома, снизить число осложнений, длительность ИВЛ и пребывания боль- ного в ОРИТ, инвалидизацию и смертность. Подбор патогенетической, симптоматической, а затем поддерживающей терапии значительно улучшает реабилитационный потенциал пациентов

Prevention of traumatic brain injury complications in sports

The aim of the review is to inform doctors and trainers of sports teams about technologies that prevent complications of sport brain injuries (SBI). Low levels of visibility of clinical manifestations, specific characteristics of individual reactions to injury, anti-aggravation behavior among sportsmen, absence of unbiased methods of diagnostics of SBI are the main reasons behind underestimation of the severity of trauma. Treatment and rehabilitation procedures of mild SBI do not currently consider specific characteristics of trauma, associated with the increase in body and brain temperature and reduced cerebral perfusion during the traumatizing intervention. Injury of the brain causes an increase in cerebral temperature, which, in turn, can aggravate the consequences of traumatization. The control of the temperature of the brain can be achieved with non-invasive method of microwave radiometry, while the technology of craniocerebral hypothermia (CCH), which has evident neuroprotective properties, can aid in the prevention of complications of SBI

New Debris Disks Around Nearby Main Sequence Stars: Impact on The Direct Detection of Planets

Using the MIPS instrument on the Spitzer telescope, we have searched for infrared excesses around a sample of 82 stars, mostly F, G, and K main-sequence field stars, along with a small number of nearby M stars. These stars were selected for their suitability for future observations by a variety of planet-finding techniques. These observations provide information on the asteroidal and cometary material orbiting these stars - data that can be correlated with any planets that may eventually be found. We have found significant excess 70um emission toward 12 stars. Combined with an earlier study, we find an overall 70um excess detection rate of $13 \pm 3$% for mature cool stars. Unlike the trend for planets to be found preferentially toward stars with high metallicity, the incidence of debris disks is uncorrelated with metallicity. By newly identifying 4 of these stars as having weak 24um excesses (fluxes $\sim$10% above the stellar photosphere), we confirm a trend found in earlier studies wherein a weak 24um excess is associated with a strong 70um excess. Interestingly, we find no evidence for debris disks around 23 stars cooler than K1, a result that is bolstered by a lack of excess around any of the 38 K1-M6 stars in 2 companion surveys. One motivation for this study is the fact that strong zodiacal emission can make it hard or impossible to detect planets directly with future observatories like the {\it Terrestrial Planet Finder (TPF)}. The observations reported here exclude a few stars with very high levels of emission, $>$1,000 times the emission of our zodiacal cloud, from direct planet searches. For the remainder of the sample, we set relatively high limits on dust emission from asteroid belt counterparts