Experimental investigation of surface litter ignition by bark firebrands

Probability and conditions for ignition of surface litter (pine needles) caused by firebrands is studied in the laboratory conditions. For modeling of firebrands, pine bark of various sizes 10×10, 15×15, 20×20, 25×25, 30×30 mm2 and 5 mm in thickness is used. The experiment was conducted in the absence of wind and at different wind velocities: 1, 1.5, 2 and 3 m/s. To conduct investigations, an experimental setup was constructed for generation of firebrands and their impact on surface litter. The results of experiments have shown that the increase in air velocity leads to the increase in probability of surface litter ignition. Thus, wind plays a role of catalyst in the ignition process, bringing an oxidizing agent to firebrands and supporting the process of smoldering. However, if the wind velocity is insufficient for ignition, then there is only the process of smoldering. The area of “uncertainty”, where there is smoldering of surface litter without transition to ignition, is found to decrease with increasing the wind velocity. Based on the received results, it can be concluded that the ignition curve of surface liter by firebrands is nonlinear and depends on the wind velocity. At the same time, there is no smoldering and ignition of surface litter for all the wind velocities and the particles with a size of 10 × 10 mm2, regardless of their number

Increased Energy Demand during Adrenergic Receptor Stimulation Contributes to Ca2+ Wave Generation

AbstractWhile β-adrenergic receptor (β-AR) stimulation ensures adequate cardiac output during stress, it can also trigger life-threatening cardiac arrhythmias. We have previously shown that proarrhythmic Ca2+ waves during β-AR stimulation temporally coincide with augmentation of reactive oxygen species (ROS) production. In this study, we tested the hypothesis that increased energy demand during β-AR stimulation plays an important role in mitochondrial ROS production and Ca2+-wave generation in rabbit ventricular myocytes. We found that β-AR stimulation with isoproterenol (0.1 μM) decreased the mitochondrial redox potential and the ratio of reduced to oxidated glutathione. As a result, β-AR stimulation increased mitochondrial ROS production. These metabolic changes induced by isoproterenol were associated with increased sarcoplasmic reticulum (SR) Ca2+ leak and frequent diastolic Ca2+ waves. Inhibition of cell contraction with the myosin ATPase inhibitor blebbistatin attenuated oxidative stress as well as spontaneous SR Ca2+ release events during β-AR stimulation. Furthermore, we found that oxidative stress induced by β-AR stimulation caused the formation of disulfide bonds between two ryanodine receptor (RyR) subunits, referred to as intersubunit cross-linking. Preventing RyR cross-linking with N-ethylmaleimide decreased the propensity of Ca2+ waves induced by β-AR stimulation. These data suggest that increased energy demand during sustained β-AR stimulation weakens mitochondrial antioxidant defense, causing ROS release into the cytosol. By inducing RyR intersubunit cross-linking, ROS can increase SR Ca2+ leak to the critical level that can trigger proarrhythmic Ca2+ waves

Weinberg propagator of a free massive particle with an arbitrary spin from the BFV-BRST path integral

The transition amplitude is obtained for a free massive particle of arbitrary spin by calculating the path integral in the index-spinor formulation within the BFV-BRST approach. None renormalizations of the path integral measure were applied. The calculation has given the Weinberg propagator written in the index-free form with the use of index spinor. The choice of boundary conditions on the index spinor determines holomorphic or antiholomorphic representation for the canonical description of particle/antiparticle spin.Comment: 31 pages, Latex, version published in Class. Quantum Gra

Etiopathogenetic parallels and unresolved issues of pathogenesis of comorbidity COPD and metabolic syndrome (review)

The review analyzes the etiological and pathogenetic factors (including immunopathogenesis factors) of chronic obstructive pulmonary disease (COPD) and metabolic syndrome (MS), cites data on clinical and pathogenetic characteristics of combined pathology, emphasizes the commonality of risk factors and individual links of pathogenesis in syntropy.The clinical and pathogenetic features of the comorbidity of COPD and MS are closely related to the severity of chronic “metabolic” inflammation induced by elements of adipose tissue. Functional and biochemical disorders recorded in metabolic syndrome (insulin resistance, hyperglycemia, dyslipidemia) are considered as factors contributing to dysfunction of the components of innate and adaptive immunity.The review formulates a number of unresolved issues of the pathogenesis of comorbid pathology, the study of which is necessary to search for the mutual aggravating effect of COPD and MS mechanisms. In view of the clinical and laboratory metabolic syndrome equivalents variety, the authors emphasize the relevance of future studies of the pathogenetic features of chronic inflammation associated with the comorbidity of the main components of metabolic syndrome and COPD, to develop effective methods of prevention and pathogenetic therapy of comorbid pathology

Asteroseismology with the WIRE satellite. I. Combining Ground- and Space-based Photometry of the Delta Scuti Star Epsilon Cephei

We have analysed ground-based multi-colour Stromgren photometry and single-filter photometry from the star tracker on the WIRE satellite of the delta scuti star Epsilon Cephei. The ground-based data set consists of 16 nights of data collected over 164 days, while the satellite data are nearly continuous coverage of the star during 14 days. The spectral window and noise level of the satellite data are superior to the ground-based data and this data set is used to locate the frequencies. However, we can use the ground-based data to improve the accuracy of the frequencies due to the much longer time baseline. We detect 26 oscillation frequencies in the WIRE data set, but only some of these can be seen clearly in the ground-based data. We have used the multi-colour ground-based photometry to determine amplitude and phase differences in the Stromgren b-y colour and the y filter in an attempt to identify the radial degree of the oscillation frequencies. We conclude that the accuracies of the amplitudes and phases are not sufficient to constrain theoretical models of Epsilon Cephei. We find no evidence for rotational splitting or the large separation among the frequencies detected in the WIRE data set. To be able to identify oscillation frequencies in delta scuti stars with the method we have applied, it is crucial to obtain more complete coverage from multi-site campaigns with a long time baseline and in multiple filters. This is important when planning photometric and spectroscopic ground-based support for future satellite missions like COROT and KEPLER.Comment: 13 pages, 12 figures, 4 tables. Fig. 4 reduced in quality. Accepted by A&

Subcellular heterogeneity of ryanodine receptor properties in ventricular myocytes with low T-tubule density

Rationale: In ventricular myocytes of large mammals, not all ryanodine receptor (RyR) clusters are associated with T-tubules (TTs); this fraction increases with cellular remodeling after myocardial infarction (MI). Objective: To characterize RyR functional properties in relation to TT proximity, at baseline and after MI. Methods: Myocytes were isolated from left ventricle of healthy pigs (CTRL) or from the area adjacent to a myocardial infarction (MI). Ca2+ transients were measured under whole-cell voltage clamp during confocal linescan imaging (fluo-3) and segmented according to proximity of TTs (sites of early Ca2+ release, F>F50 within 20 ms) or their absence (delayed areas). Spontaneous Ca2+ release events during diastole, Ca2+ sparks, reflecting RyR activity and properties, were subsequently assigned to either category. Results: In CTRL, spark frequency was higher in proximity of TTs, but spark duration was significantly shorter. Block of Na+/Ca2+ exchanger (NCX) prolonged spark duration selectively near TTs, while block of Ca2+ influx via Ca2+ channels did not affect sparks properties. In MI, total spark mass was increased in line with higher SR Ca2+ content. Extremely long sparks (>47.6 ms) occurred more frequently. The fraction of near-TT sparks was reduced; frequency increased mainly in delayed sites. Increased duration was seen in near-TT sparks only; Ca2+ removal by NCX at the membrane was significantly lower in MI. Conclusion: TT proximity modulates RyR cluster properties resulting in intracellular heterogeneity of diastolic spark activity. Remodeling in the area adjacent to MI differentially affects these RyR subpopulations. Reduction of the number of sparks near TTs and reduced local NCX removal limit cellular Ca2+ loss and raise SR Ca2+ content, but may promote Ca2+ waves

Iron metabolism parameters and inflammatory status in patients with diabetes mellitus and dyslipidemia

Background: Investigating the inflammatory status and iron metabolism in patients with impaired carbohydrate metabolism seems quite relevant, while only few studies are devoted to the relationship between metabolic parameters, including lipid profile, inflammatory status indicators and the state of ferrokinetics in diabetes mellitus types 1 and 2 in a comparative aspect.Aims: To establish the direction of changes in the inflammatory status and the state of ferrokinetics in patients with type 1 and type 2 diabetes mellitus depending on lipid metabolism disorders.Materials and methods: The study included 48 patients with type 1 diabetes, 81 patients with type 2 diabetes; 11 people with obesity without impaired carbohydrate metabolism made up the comparison group, 17 healthy volunteers - the control group. Low-grade inflammation was assessed by the levels of high-sensitive C-reactive protein (CRP), tumor necrosisfactor-а (TNF-а), ferritin, and erythrocyte sedimentation rate (ESR). The state of iron metabolism was evaluated by the main hematological parameters (hemoglobin, red blood cell count, hematocrit), serum iron concentrations, transferrin, ferritin and hepcidin concentrations. In all patients lipid metabolism parameters, glycated hemoglobin, and microalbuminuria were measured.Results: Patients with type 1 and type 2 diabetes mellitus had significantly higher inflammatory markers concentrations-TNF-а, ESR, and CRP - in relation to obese patients without impaired carbohydrate metabolism and those in the control group. The highest production of TNF-а was observed in patients with type 1 diabetes mellitus (15.28 [12.41-24.41] pg/ml), whereas CRP (7.00 [3.00-11.85] ng/ml) and ESR (18.00 [9.00-27.00] mm/h) were higher in patients with type 2 diabetes. In the structure of the examined individuals with diabetes mellitus (regardless of its type), dyslipidemia type IIb in comparison with less atherogenic type IIa dyslipidemia was characterized by a higher production of CRP (6.9 [3.00-12.35] and 3.00 [1.80-8.70] ng/ml, respectively), ESR (20.00 [10.00-30.00] and 15.00 [5.00-24.50] mm/h, respectively) and ferritin (114.80 [48.90-196.45] and 50.90 [19.58-114.10] ng/ml, respectively). Compared to iron deficiency anemia, anemia of chronic diseases in diabetes mellitus patients was more often accompanied by dyslipidemia llb (χ2=2.743; p=0.098) and was characterized by a higher content of atherogenic fractions of cholesterol.Conclusions: Patients with type 2 diabetes mellitus and a more atherogenic dyslipidemia profile (type IIb) have a phenotype of the local inflammatory mesenchymal reaction of the liver with an increase in acute-phase proteins predominantly of hepatic origin (CRP, ferritin), whereas individuals suffering from type 1 diabetes and less atherogenic lipid profile (type IIa) have a phenotype of an autoimmune, genetically determined inflammatory response. It has been established that anemia of chronic diseases developing in the background of diabetes mellitus is associated with a more atherogenic lipid profile, compared with iron deficiency anemia

An asteroseismic study of the Delta Scuti star 44 Tau

In this paper we investigate theoretical pulsation models for the delta Scuti star 44 Tau. The star was monitored during several multisite campaigns which confirmed the presence of radial and nonradial oscillations. Moreover, its exceptionally low rotational velocity makes 44 Tau particulary interesting for an asteroseismic study. Due to the measured log g value of 3.6 +/- 0.1, main sequence and post-main sequence models have to be considered. We perform mode identification based on photometric and spectroscopic data. A nonadiabatic pulsation code is used to compute models that fit the identified modes. The influence of different opacity tables and element mixtures on the results is tested. The observed frequencies of 44 Tau can be fitted in both the main sequence and the post-main sequence evolutionary stage. Post-main sequence models are preferable as they fulfill almost all observational constraints (fit of observed frequencies, position in the HRD and instability range). These models can be obtained with normal chemical composition which is in agreement with recent spectroscopic measurements. The efficiency of envelope convection (in the framework of the mixing-length theory) is predicted to be very low in 44 Tau. We show that the results are sensitive to the choice between the OPAL and OP opacities. While the pulsation models of 44 Tau computed with OP opacities are considerably too cool and too faint, the use of OPAL opacities results in models within the expected temperature and luminosity range.Comment: 9 pages, 15 figures, 2 tables, accepted for publication in A&

ОТРИМАННЯ БОРОВАНИХ ПОКРИТТІВ В УМОВАХ САМОРОЗПОВСЮДЖУВАЛЬНОГО ВИСОКОТЕМПЕРАТУРНОГО СИНТЕЗУ ДЛЯ ДЕТАЛЕЙ ГАЗОРОЗПОДІЛЬНОГО МЕХАНІЗМУ ДВИГУНІВ ВНУТРІШНЬОГО ЗГОРАННЯ АВТОМОБІЛІВ

The article presents the results of obtaining protective coatings under SHS conditions. It has been established that the main criterion in determining the optimal technological parameters for obtaining protective coatings in the thermal self-ignition mode is the diffusion layer thickness (h, μm), the distribution of the diffusion element concentration over the layer thickness, the phase composition and layer properties (heat resistance, adhesive strength, corrosion resistance, wear resistance). The structure of the surface layers significantly depends on the composition of the saturating mixture, the choice of the coating temperature and the duration of the process. The main technological parameters affecting the formation of coatings in the thermal self-ignition mode are: ignition temperature (t*,ºC), maximum temperature (tm,ºC), isothermal holding temperature (t,ºC), isothermal holding time (τ, min) and heating rate (v, C/min). After carrying out the borochromoalitivan layer, it has a characteristic needle-like structure. Boride needles form a continuous layer of borides with aluminum inclusions. The microstructures of the borochromo-aluminized coating for different exposure times have the following phases (Fe, Cr, Al)2B under which there is an α-solid solution of Cr, Al and B in iron. The studies carried out at the pilot plant, consist of the following main functional systems: reaction equipment, gas supply system, process parameters control and regulation system. The kinetics of the formation of borochrome coatings was studied at a process temperature of 1050ºC for 60 minutes. A borochromoalitization coating with a thickness of 45-80 µm was obtained. With a microhardness of 15-17 · 103 MPa. As a result of the study on the friction machine SMT-1 to 5:00 of the experiment, it was found that samples with different types of coatings wear 155-175·10-4 g /m2.В статье приведены результаты получения защитных покрытий в условиях СВС. Установлено, что основными критериями при определении оптимальных технологических параметров получения защитных покрытий в режиме теплового самовоспламенения является толщина диффузионного слоя (h, мкм), распределение концентрации диффузионного элемента по толщине слоя, фазовый состав и свойства слоя (жаростойкость, адгезионная прочность, коррозионная стойкость, износостойкость). Строение поверхностных слоев существенно зависит от состава насыщающей смеси, выбора режима нанесения покрытий, температуры и продолжительности процесса. Основными технологическими параметрами, влияющими на процессы формирования покрытий в режиме теплового самовоспламенения являются: температура воспламенения (t*, ºC), максимальная температура (tм, ºC), температура изотермической выдержки (t, ºC), время изотермической выдержки (τ, мин.) и темп нагрева (v, C/мин.).  После проведения борохромоалитирования слой имеет характерную игольчатую структуру. Иглы боридов образуют сплошной слой боридов с включениями алюминия. Микроструктуры борохромоалитованного покрытия для различных времен выдержки имеют следующие фазы (Fe, Cr, Al)2B под которым находится α-твердый раствор Cr, Al и B в железе. Проведенные исследования на опытно-промышленной установке, состоят из следующих основных функциональных систем: реакционное оборудование, система газоснабжения, система контроля и регулирования технологических параметров. Исследована кинетика формирования борохромоалитированных покрытий при температуре процесса 1050 ºC 60 минут. Получено борохромоалитированные покрытия толщиной 45—80 мкм. с микротвердостью 15—17 103 МПа. В результате проведенных исследований на машине трения СМТ-1, в течение 5 часов  установлено, что образцы с различным типом покрытия имеют износ 155-175·10-4 г / м2.У статті наведено результати отримання захисних покриттів в умовах СВС. Встановлено, що основними критеріями при визначенні оптимальних технологічних параметрів одержання захисних покриттів в режимі теплового самозаймання є товщина дифузійного шару (h, мкм), розподіл концентрації дифузійного елемента по товщині шару, фазовий склад і властивості шару (жаростійкість, адгезійна міцність, корозійна стійкість, зносостійкість). Будова поверхневих шарів істотно залежить від складу насичуючої суміші, вибору режиму нанесення покриттів, температури і тривалості процесу. Основними технологічними параметрами, що впливають на процеси формування покриттів в режимі теплового самозаймання, є: температура займання (t*, ºC), максимальна температура процесу (tм, ºC), температура ізотермічної витримки (t, ºC), час ізотермічної витримки (τ, хв.) і темп нагріву (v, C/хв.). Після проведення борохромоалітування шар має характерну голчату будову. Голки боридів утворюють суцільний шар боридів з включеннями алюмінію. Мікроструктури борохромоалітованного покриття для різних часів витримки мають  наступні фази (Fe, Cr, Al)2B, під якими знаходиться α-твердий розчин Cr, Al та B в залізі. Проведені випробування на дослідно-промисловій установці, яка складається з наступних основних функціональних систем: реакційного обладнання, газопостачання, контролю і регулювання технологічними параметрами. Досліджено кінетику формування борохромоалітованих покриттів при температурі процесу 1050 ºC за 60 хвилин. Отримано борохромоалітовані покриття товщиною 45—80 мкм з мікротвердістю 15—17 ·103 МПа. В результаті проведення дослідження на машині тертя СМТ-1 за 5 годин експерименту встановлено, що зразки з різним типом покриття мають знос 155-175·10-4 г/м2

The question of differential diagnosis of anemia in diabetes mellitus

BACKGROUND: High prevalence of anemia in diabetes mellitus (DM) determines the relevance of studying its pathogenetic aspects, the role of anemia in DM complications development and the issue of differential diagnosis between iron deficiency anemia (IDA) and anemia of chronic disease (ACD)).AIM: To establish the diagnostic value of classical parameters for diagnosing anemia in DM and propose an optimized algorithm for the differential diagnosis of ACD and IDA in DM type 1 and 2 using new markers.MATERIALS AND METHODS: The observational, single-centre, comparative, controlled, single-stage study. Patients underwent assessment of glycated hemoglobin, creatinine, microalbuminuria; indicators of iron metabolism — hematocrit, the number of erythrocytes, reticulocytes, hemoglobin, serum iron, transferrin, ferritin, the level of soluble transferrin receptors (sTfR), sTfR/logFerpitin index, and inflammation markers — erythrocyte sedimentation rate (ESR), leukocyte count, high sensitive CRP and TNF-α. ROC-analysis was used to assess the differential diagnosis markers informative content.RESULTS: We examined 135 patients: 51 with DM 1 and 84 with DM 2. The patients were stratified into groups based on anemia type: 1) ACD 2) IDA 3) latent iron deficiency 4) without ferrokinetics disorders. According to the ROC-analysis in DM patients, the following parameters had high information content in ACD. ESR — sensitivity 92%, specificity 85%, diagnostic threshold 26.5 mm/h (area under the curve (AUC) 0.943; p<0.0001); leukocyte count — sensitivity 69%, specificity 64%, diagnostic threshold 7.50x109/l (AUC 0.727; p=0.007), microalbuminuria — sensitivity 71%, specificity 72%, diagnostic threshold 29.5 mg/l (AUC 0.744; p=0.003). In DM sTfR and the sTfR /logFerritin index had high information content in IDA at diagnostic thresholds different from those for general population. The sensitivity of sTfR 71%, the specificity 71%, diagnostic threshold 1.42 ng/mL (2.9 ng/mL for general population) (AUC 0.765; p=0.024). The sensitivity of sTfR/logFerritin index 100%, the specificity 97%, diagnostic threshold 1.48 (2.0 for general population) (AUC 0.983; p=0.024).CONCLUSION: In differential diagnosis of IDA and ACD in DM, ESR, leukocyte count, microalbuminuria, sTfR and sTfR/logFerritin index have a high diagnostic value. This allows proposing them as additional markers for differential diagnosis of anemia in DM