358 research outputs found

    Muonic Hydrogen and the Third Zemach Moment

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    We determine the third Zemach moment of hydrogen (_(2)) using only the world data on elastic electron-proton scattering. This moment dominates the O (Z alpha)^5 hadronic correction to the Lamb shift in muonic atoms. The resulting moment, _(2) = 2.71(13) fm^3, is somewhat larger than previously inferred values based on models. The contribution of that moment to the muonic hydrogen 2S level is -0.0247(12) meV.Comment: 3 pages, no figures, revtex - submitted to Physical Review

    Модификация ускоренной термостабилизации полиакрилонитрильных волокон созданием градиента концентрации кислорода при получении углеродного волокна

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    Objectives. The work set out to modify the technology of accelerated thermal stabilization of polyacrylonitrile (PAN) fibers used in the production of high-strength carbon fibers by reducing the formation of a heterophase core–shell structure to create an oxygen concentration gradient in heat treatment furnaces while maintaining a total thermal stabilization time of 30 min. The optimized process conditions led to milder thermal stabilization conditions, reducing both the final heat treatment temperature and the temperature difference between the thermal stabilization zones while simultaneously maintaining the target volume density parameter with respect to the previously developed accelerated thermal stabilization technology.Methods. The thermal stabilization study of an industrially produced 12S precursor under different conditions on an experimental carbon fiber production line included measurement of bulk density, analysis of the thermal effects of the oxidation reaction by differential scanning calorimetry (DSC), and a study of micrographs of the resulting samples.Results. The optimum process of thermal stabilization of PAN fiber was determined in four stabilization zones using selected compositions. The formation of the core–shell structure is significantly reduced when the target volume density and DSC thermal oxidation reaction effect of the stabilized polymer fiber are achieved in a given time (30 min).Conclusions. The resulting technology regime is promising for the production of high strength (4.5 GPa, 4.9 GPa) PAN fibers at a reduced cost. While maintaining the total thermal stabilization time of PAN at the level of 30 min, which is three times less than the industrial processes used, it was possible to reduce the formation of a heterophase structure, as well as lowering the final processing temperature and reducing the temperature difference between the stabilization zones. This is promising in terms of a positive effect on the stability and safety of the industrial process, as well as ensuring the quality of the obtained products.Цели. Модифицировать технологию ускоренной термостабилизации полиакрилонитрильного (ПАН) волокна при производстве высокопрочных углеродных волокон, при помощи которой удастся уменьшить образование гетерофазной структуры «ядро–оболочка» путем создания градиента концентрации кислорода в печах термообработки при сохранении общего времени термостабилизации ПАН (30 мин); оптимизировать процесс на основании предлагаемого режима с целью получения более мягких условий термостабилизации: снижения конечной температуры термообработки и разницы температур между зонами термостабилизации при сохранении целевого параметра объемной плотности (относительно ранее разработанной технологии ускоренной термостабилизации).Методы. Термостабилизация промышленно выпускаемого прекурсора марки 12S в различных условиях на опытной линии получения углеродных волокон, последующее измерение объемной плотности, анализ тепловых эффектов реакции окисления методом дифференциальной сканирующей калориметрии (ДСК) и изучение микрофотографий шлифов получаемых образцов.Результаты. Определен оптимальный процесс термостабилизации ПАН волокна в 4 зонах стабилизации с использованием подобранных составов, при котором существенно снижается образование структуры «ядро–оболочка» при достижении целевой объемной плотности и теплового эффекта реакции окисления ДСК стабилизируемого полимерного волокна за установленное время (30 мин).Выводы. Полученный технологический режим является перспективным для получения высокопрочных (4.5 ГПа, 4.9 ГПа) ПАН волокон со сниженной себестоимостью. При сохранении общего времени термостабилизации ПАН на уровне 30 мин, что в 3 раза меньше используемых промышленных процессов, удалось снизить образование гетерофазной структуры, уменьшить конечную температуру обработки и снизить перепад температур между зонами стабилизации, что должно положительно сказаться на стабильности и безопасности ведения промышленного процесса и качестве получаемой продукции

    The Anticancer Peptide TAT-RasGAP317-326 Exerts Broad Antimicrobial Activity.

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    Antibiotic resistance has become a major health issue. Nosocomial infections and the prevalence of resistant pathogenic bacterial strains are rising steadily. Therefore, there is an urgent need to develop new classes of antibiotics effective on multi-resistant nosocomial pathogenic bacteria. We have previously shown that a cell-permeable peptide derived from the p120 Ras GTPase-activating protein (RasGAP), called TAT-RasGAP317-326, induces cancer cell death, inhibits metastatic progression, and sensitizes tumor cells to various anti-cancer treatments in vitro and in vivo. We here report that TAT-RasGAP317-326 also possesses antimicrobial activity. In vitro, TAT-RasGAP317-326, but not mutated or truncated forms of the peptide, efficiently killed a series of bacteria including Escherichia coli, Acinetobacter baumannii, Staphylococcus aureus, and Pseudomonas aeruginosa. In vivo experiments revealed that TAT-RasGAP317-326 protects mice from lethal E. coli-induced peritonitis if administrated locally at the onset of infection. However, the protective effect was lost when treatment was delayed, likely due to rapid clearance and inadequate biodistribution of the peptide. Peptide modifications might overcome these shortcomings to increase the in vivo efficacy of the compound in the context of the currently limited antimicrobial options

    Оптимизация параметров тепловой обработки при сканирующем перемещении точечного источника тепла

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    Трофименко Е. Г. Оптимизация параметров тепловой обработки при сканирующем перемещении точечного источника тепла / Е. Г. Трофименко, Е. В. Шалабин, В. В. Дубовой // Труды Одесского политехнического университета. – 1998. – Вып. 2(6). – С. 186 – 187.Задача теплової обробки розвиненої поверхні за допомогою точкового джерела тепла подана як оптимізаційна. Наведено цільову функцію оптимізації та алгоритм розв'язання такої задачі.Задача тепловой обработки развитой поверхности с помощью точечного источника тепла подана как оптимизационная . Приведены целевая функция оптимизации и алгоритм решения такой задачи.The problem of developed surface thermal processing by the mean of pointwised heat source is considered herewith as this one of optimisation. A target oriented function of optimisation and problem solution algorithm are given

    Formation of extracellular traps by circulating neutrophils and monocytes in rheumatoid arthritis patients: a study of new citrullinated autoantigen

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    Detection of subcellular structures containing typical citrullinated rheumatoid autoantigens in a single compartment presents a special interest, due to importance of anticitrulline autoantibodies for the autoimmune response in RA. Neutrophil and monocyte extracellular traps (NETs and ETs, respectively) may be considered such candidate structures. Our objective was to assess ability of blood neutrophils and monocytes from RA patients to generate NETs and ETs spontaneously and after in vitro induction.32 patients with verified RA and 30 healthy volunteers as controls were included into the study. Circulating neutrophils and monocytes were isolated with one-step density gradient centrifugation using three layers of ficoll-amidotrizoate gradient. Composition of isolated cellular fractions, their viability, and non-specific activation were evaluated microscopically using Trypan Blue exclusion test, as well as Nitro-Blue Tetrazolium test. The NETs were induced by phorbol-12-myristate-13-acetate, and ETs by bacterial LPS. Spontaneous and induced formation of extracellular traps was assessed using fluorescence microscopy. Neutrophil and monocyte fractions contained minute percentages of impurities and low extents of activated and dead cells. Spontaneous NET and ET formation in RA patients was significantly increased comparing to healthy controls. Neutrophils from ACPA-positive RA patients were found to have higher frequency of NET formation, compared to ACPA-negative RA patients. The monocytes did not demonstrate such differences between these subgroups. There were no substantial morphological differences in NETs and ETs patterns between the individuals from both groups. Induced extracellular trap production in RA was significantly higher compared to healthy controls. The level of myeloperoxidase-specific fluorescence in ETs was considerably lower than in NETs. NETs could probably be considered as a source of citrulline autoantigen participating in autoantibody production and stimulation of inflammatory autoimmune responses in RA, whereas ETs may play less important role in this process

    Effect of reactive inflammation in osteoarthritis on extracellular traps formation by circulating neutrophils

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    The results of recent studies demonstrating the presence of pro-inflammatory mediators in osteoarthritis (OA), as well as known similarity of histological signs of inflammation in rheumatoid arthritis (RA) and OA, suggest an important role of NETosis in immune inflammation in OA patients. Our objective was to assess ability of blood neutrophils from ОA patients to generate NETosis spontaneously and after in vitro induction, and impact of reactive synovitis on the dynamics of NETosis indexes. Thirty-one patients with verified OA and 30 healthy volunteers were included into the study. Circulating neutrophils were isolated with one-step density gradient centrifugation using double layers of Iohexol gradient. Subpopulational profile of isolated neutrophil fractions, their viability, and nonspecific activation were evaluated microscopically using Trypan Blue exclusion test, as well as nitro-blue tetrazolium test. NETs were induced by phorbol-12-myristate13-acetate (PMA). Spontaneous and induced formation of NETs was assessed using fluorescence microscopy. The ОA patients were in clinical remission at the time of inclusion in the study. In 23 OA patients, an exacerbation was diagnosed during the study. The neutrophil fractions showed high purity and a high content of viable nonactivated cells. These parameters were comparable in the study groups. Mean percentage of spontaneous NETs in OA patients in remission was significantly increased comparing to healthy controls. Usage of PMA, as inducing agent was accompanied by a significant increase in ability of neutrophils to form NETs. Transition of OA to exacerbation was characterized by further significant increase in spontaneous and PMA-induced NETs. Spontaneous and induced NETs in OA patients at acute stage of the disease are significantly higher than in OA patients in remission state. The growth rate of spontaneous NET formation is 3.74 times higher than the induced NET formation in OA patients upon exacerbation. Statistically significant increase in the ability of peripheral neutrophils to spontaneous and induced formation of extracellular traps was found, depending on the stage of osteoarthritis. The data obtained suggest an opportunity for participation of circulating neutrophils via NETosis in pathogenesis of immune inflammation in OA

    Antiatherogenic Potential of Transcranial Electrical Stimulation in a High-Fructose/High-Fat Diet: Experimental Randomized Trial

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    Background. Transcranial electrical stimulation is a promising method for correction of malnutrition-induced hyperlipidemia, in the absence of indications for drug hypolipidemic therapy in young and middle-aged patients with low and moderate cardiovascular risk. Objectives — to study the effect of transcranial electrical stimulation on lipid metabolism in a high-fructose/high-fat (HFHF) diet in rats.Methods. An experimental randomized trial was performed to study the effect of transcranial electrical stimulation on lipid metabolism in a high-calorie diet enriched with fructose and saturated animal fat in rats. The experiments involved 180 outbred male rats and were carried out on the basis of the vivarium of Kuban State Medical University. The animals were divided into three groups: group 1 (control group, n = 60) — followed a standard diet; group 2 (comparison group, n = 60) — followed a HFHF diet; group 3 (experimental group, n = 60) — underwent transcranial electrical stimulation against the background of a HFHF diet. According to the target reference point of the study, the groups were divided into three equal subgroups of 20 rats each: subgroup A — day 30, subgroup B — day 60, and subgroup C — day 90 (biomaterial sampling and euthanasia were carried out on those days). In the obtained blood samples, the following lipid metabolism parameters were evaluated: total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and atherogenic index. Statistical analysis was performed using Microsoft Office Excel 2021 (Microsoft, USA), GraphPadPrism 9 (GraphPad Software, USA) and Statistica 13.3 (StatSoft, USA).Results. On the 30th day of the study, it was noted that in group 3, the concentration of low-density lipoprotein cholesterol was 14.9% lower and the atherogenic index was 30.8% lower (p < 0.05) than in group 2, while total cholesterol concentration, triglycerides, and high-density lipoprotein cholesterol had no statistically significant differences (p > 0.05). On the 60th day of the study, in group 3, when compared to group 2, the concentration of total cholesterol was 18.7% lower, low-density lipoprotein cholesterol was 42.9% lower, high-density lipoprotein cholesterol was 16.7% higher, and the atherogenic index was 56.3% lower (p < 0.05), while triglycerides had no statistically significant differences (p > 0.05). On the 90th day of the study, in group 3, when compared to group 2, the concentration of total cholesterol was 29.2% lower, the concentration of triglycerides was 36.0% lower, low-density lipoprotein cholesterol was 42.8% lower, and the atherogenic index was 57.0% lower (p < 0.05), while the concentration of high-density lipoprotein cholesterol had no statistically significant differences (p > 0.05).Conclusion. High-fructose/high-fat diet leads to a progressive increase in the serum concentration of low-density lipoprotein cholesterol, total cholesterol, triglycerides, as well as to a moderate decrease in high-density lipoprotein cholesterol and a growth in the atherogenic index. Transcranial electrical stimulation has a moderate lipid-lowering effect, manifested in the form of a decrease in the serum concentration of low-density lipoprotein cholesterol, total cholesterol and atherogenic index, while the effect on the concentration of triglycerides and high-density lipoprotein cholesterol is insignificant

    tPCS as a method for correcting cardiac arrhythmias after percutaneous transluminal coronary angioplasty with stenting in patients with myocardial infarction

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    Objective: To study the effect of transcranial pulsed current stimulation (tPCS) therapy on cardiac arrhythmias developed after percutaneous transluminal coronary angioplasty (PTCA) with stenting in patients with myocardial infarction (MI).Material and methods: Characteristics of patient groups: the comparison group (n = 17) – with myocardial infarction, after PTCA with stenting, standard treatment; the main group (n = 21) – the same and tPCS therapy. Control points of the study: 1st day – Electrocardiography (ECG), Echocardiography (ECHO), Creatine phosphokinase (CPK), Creatine phosphokinase-MB (CPK-MB), Troponin-I, potassium, β-endorphin; 5th day – the same without ECHO; 10th day – the same and ECG with the determination of harmony and quantum of the electromagnetic flux of the cardiac cycle. PTCA was performed using drug-eluting stents. tPCS therapy was performed in pulsed bipolar mode, current strength 2 mA, current frequency 77.5 Hz, session duration 45 min.Results: In patients of the main group (against the background of tPCS therapy), the studied parameters of the cardiac cycle approached the optimal values. It was shown that intergroup differences in harmony (p = 0.002) and the size of the electromagnetic flux quantum of the cardiac cycle (p = 0.001) are statistically significant. Also, against the background of the tPCS therapy, the concentration of highly sensitive troponin-I is statistically significantly (p = 0.0042) lower by 109%. On the 5th and 10th days of the study, the serum concentration of β-endorphin in the main group was higher by 38.3 and 35.0% than in the comparison group (p < 0.05).Conclusion: The results of the study clearly demonstrate the cardioprotective and antiarrhythmic potential of tPCS therapy in patients with myocardial infarction and cardiac arrhythmias after PTCA with stenting

    Моделирование оптимальных геометрических параметров пьезоэлементов для полизмерительных мономорфных датчиков

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    Салагор А. М. Моделирование оптимальных геометрических параметров пьезоэлементов для полизмерительных мономорфных датчиков / А. М. Салагор, Е. Г. Трофименко, Л. Н. Буката // Вісник Інженерної академії України. - К.: ІАУ, 2015. - № 1. - С. 151-157.В работе исследованы зависимости основных характеристик пьезокерамики от соотношений геометрических параметров пьезоэлементов в форме бруска. Исследована схемотехническая модель мономорфного пьезокерамического преобразователя для измерения двух физических величин, проведены экспериментальные исследования. В результате анализа было установлено оптимальное соотношение геометрических параметров пьезоэлемента в виде бруска.В роботі досліджено залежності основних характеристик п'єзокераміки від співвідношень геометричних параметрів п'єзоелементів у формі бруска. Досліджено схемотехнічна модель мономорфного п'єзокерамічного перетворювача для вимірювання двох фізичних величин, проведені експериментальні дослідження. В результаті аналізу було встановлено оптимальне співвідношення геометричних параметрів п'єзоелемента у вигляді бруска

    Restricted dispersal in a sea of gene flow

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    Howfar domarine larvae disperse in the ocean? Decades of population genetic studies have revealed generally low levels of genetic structure at large spatial scales (hundreds of kilometres). Yet this result, typically based on discrete sampling designs, does not necessarily imply extensive dispersal. Here, we adopt a continuous sampling strategy along 950 km of coast in the northwestern Mediterranean Sea to address this question in four species. In line with expectations, we observe weak genetic structure at a large spatial scale. Nevertheless, our continuous sampling strategy uncovers a pattern of isolation by distance at small spatial scales (few tens of kilometres) in two species. Individual- based simulations indicate that this signal is an expected signature of restricted dispersal. At the other extreme of the connectivity spectrum, two pairs of individuals that are closely related genetically were found more than 290 km apart, indicating long-distance dispersal. Such a combination of restricted dispersal with rare long-distance dispersal events is supported by a high-resolution biophysical model of larval dispersal in the study area, and we posit that it may be common in marine species. Our results bridge population genetic studies with direct dispersal studies and have implications for the design of marine reserve networksVersión del edito
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