15 research outputs found
The influence of transition metal solutes on dislocation core structure and values of Peierls stress and barrier in tungsten
Several transition metals were examined to evaluate their potential for
improving the ductility of tungsten. The dislocation core structure and Peierls
stress and barrier of screw dislocations in binary
tungsten-transition metal alloys (WTM) were investigated using
first principles electronic structure calculations. The periodic quadrupole
approach was applied to model the structure of dislocation. Alloying
with transition metals was modeled using the virtual crystal approximation and
the applicability of this approach was assessed by calculating the equilibrium
lattice parameter and elastic constants of the tungsten alloys. Reasonable
agreement was obtained with experimental data and with results obtained from
the conventional supercell approach. Increasing the concentration of a
transition metal from the VIIIA group, i.e. the elements in columns headed by
Fe, Co and Ni, leads to reduction of the elastic constant and
increase of elastic anisotropy A=. Alloying W with a group
VIIIA transition metal changes the structure of the dislocation core from
symmetric to asymmetric, similar to results obtained for WRe
alloys in the earlier work of Romaner {\it et al} (Phys. Rev. Lett. 104, 195503
(2010))\comments{\cite{WRECORE}}. In addition to a change in the core symmetry,
the values of the Peierls stress and barrier are reduced. The latter effect
could lead to increased ductility in a tungsten-based
alloy\comments{\cite{WRECORE}}. Our results demonstrate that alloying with any
of the transition metals from the VIIIA group should have similar effect as
alloying with Re.Comment: 12 pages, 8 figures, 3 table
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Progress in Development of Kharkov X-Ray Generator Nestor
The sources of the X-rays based on Compton scattering of intense Nd:YAG laser beam on electron beam circulating in a storage ring with beam energy 43-225 MeV is under construction in NSC KIPT. In the paper the progress in development and construction of Kharkov X-ray generator NESTOR is presented. The current status of the main facility system design and development are described. New scheme and main parameters of injection system are presented. The status of power supply system and control system is described. The facility is going to be in operation in the middle of 2007 and generated X-rays flux is expected to be of about 10{sup 13} phot/s
Продленная заместительная почечная терапия с применением мембран с повышенной сорбционной емкостью у пациентов после нейрохирургических вмешательств с септическим шоком
Introduction. The combination of primary brain injury with cytokine storm and hemodynamic disturbance in septic shock leads to secondary brain damage and growing neurological deficit. Blood purification procedures can be considered as an additional option in the treatment of septic shock in this group of patients.Subjects and Methods. The study included 11 patients after neurosurgical interventions with septic shock and acute kidney injury who underwent continuous renal replacement therapy (CRRT) using membranes with increased adsorption capacity.Results. During CRRT there was a significant regression in severity of multiorgan dysfunction according to SOFA score, a decrease in the requirement for vasopressor support with norepinephrine, and a decrease in lactate blood level. In addition, after the end of the procedure, there was a significant decrease in procalcitonin blood level. Septic shock reversal was observed in 8/11 patients (72.7%). In 3/11 patients, neurological deficits regressed during the procedure.Conclusions. The results indicate the possibility of using CRRT with membranes with increased adsorption capacity in patients after neurosurgical interventions with septic shock. Changes in neurological status can be considered as an additional parameter for the effectiveness of therapy for septic shock in patients with primary brain injury.Сочетание первичной патологии головного мозга с цитокиновым штормом и нарушением гемодинамики при септическом шоке приводит к вторичному повреждению головного мозга и нарастанию неврологического дефицита. Проведение процедур экстракорпоральной детоксикации может быть рассмотрено в качестве дополнительной опции терапии септического шока у пациентов данной группы.Материал и методы. В исследование включены 11 пациентов после нейрохирургических вмешательств с септическим шоком и острым почечным повреждением, которым проводили продленную заместительную почечную терапию (ПЗПТ) с применением мембран с повышенной сорбционной емкостью.Результаты. На фоне интенсивной терапии септического шока с применением ПЗПТ обнаружены значимый регресс тяжести мультиорганной дисфункции по шкале SOFA, снижение потребности в вазопрессорной поддержке норадреналином и уровня лактата в крови. Кроме того, после окончания процедуры установлено значимое снижение уровня прокальцитонина в крови. Выход из септического шока был отмечен у 8/11 пациентов (72,7%), регресс неврологического дефицита на фоне процедуры ‒ у 3/11 пациентов.Выводы. Полученные результаты свидетельствуют о возможности применения ПЗПТ с мембранами с повышенной сорбционной емкостью у пациентов после нейрохирургических вмешательств с септическим шоком. Динамика неврологического статуса может быть рассмотрена в качестве дополнительного критерия эффективности терапии септического шока у пациентов с первичным церебральным повреждением
Критерии лабораторной диагностики нозокомиального менингита у пациентов отделения реанимации и интенсивной терапии. Опыт пятилетнего проспективного наблюдения
Introduction. Nosocomial meningitis (NM) is one of the leading complications in neurosurgery due to high mortality and disability rates.Objective. The study was aimed to determine the reference values of laboratory parameters to diagnose NM in neurosurgical patients in the intensive care unit (ICU).Results. The incidence of NM in neurosurgical patients in ICU was 8.4 (95% CI 6.8–10. 0) per 100 patients. The dominant microbial agents of NM were coagulase-negative staphylococci, A. baumannii, and K. pneumoniae. We revealed the increase in leukocytosis, C-reactive protein, and blood procalcitonin in patients with infectious complications of other systems, regardless of NM presence. Episodes of hyponatremia and an increase in body temperature ≥ 38.0 occurred signifcantly more often in patients with NM. Changes in cerebrospinal fluid (CSF) cytosis, glucose, lactate, and the CSF/blood glucose ratio can serve as reliable criteria in the NM diagnosis.Conclusions. The diagnosis of NM is most likely when the increase in CSF cytosis > 65 cells/μL, CSF lactate > 4.2 mmol/L is observed, the decrease in the CSF glucose < 2.6 mmol, and CSF/blood glucose ratio < 0.45 is found.Нозокомиальный менингит (НМ) является одной из ведущих проблем в нейрохирургии в связи с высоким уровнем летальности и инвалидизации.Цель: определить референсные значения лабораторных показателей в диагностике НМ у нейрохирургических пациентов в отделении реанимации и интенсивной терапии (ОРИТ).Результаты. Частота развития НМ у нейрохирургических пациентов в ОРИТ составила 8,4 (95%-ный ДИ 6,8‒10,0) на 100 больных. Доминирующими возбудителями НМ являлись: коагулазонегативные стафилококки, A. baumannii и K. Pneumoniae. Оценка лейкоцитоза, С-реактивного белка и прокальцитонина в крови выявила повышение их уровня у пациентов с инфекционными осложнениями других систем независимо от наличия НМ. Эпизоды гипонатриемии и повышения температуры тела ≥ 38,0°С встречались статистически значимо чаще у пациентов с НМ. Изменения цитоза ликвора, концентраций глюкозы в ликворе, лактата в ликворе, а также соотношения концентраций глюкозы в ликворе к глюкозе в крови (коэффициента CSF/SGlu) могут служить достоверными критериями в диагностике НМ.Выводы. Диагноз НМ наиболее вероятен: при повышении цитоза ликвора > 65 клеток в 1 мкл, лактата в ликворе > 4,2 ммоль/л; снижении концентрации глюкозы в ликворе < 2,6 ммоль/л, коэффициента CSF/SGlu < 0,45
The spread of bla OXA-48 and bla OXA-244 carbapenemase genes among Klebsiella pneumoniae, Proteus mirabilis and Enterobacter spp. isolated in Moscow, Russia
Rectal and Tracheal Carriage of Carbapenemase Genes and Class 1 and 2 Integrons in Patients in Neurosurgery Intensive Care Unit
The spread of multidrug-resistant Gram-negative bacteria, which is associated with the distribution of beta-lactamase genes and class 1 and 2 integrons, is a global problem. In this study, in the Moscow neurosurgery intensive care unit (neuro-ICU), the high prevalence of the above-stated genes was found to be associated with intestinal and tracheal carriage. Seven-point prevalence surveys, which included 60 patients in the neuro-ICU, were conducted weekly in the period from Oct. to Nov. 2019. A total of 293 clinical samples were analyzed, including 146 rectal and 147 tracheal swabs; 344 Gram-negative bacteria isolates were collected. Beta-lactamase genes (n = 837) were detected in the isolates, including beta-lactamase blaTEM (n = 162), blaSHV (n = 145), cephalosporinase blaCTX–M (n = 228), carbapenemase blaNDM (n = 44), blaKPC (n = 25), blaOXA–48 (n = 126), blaOXA–51–like (n = 54), blaOXA–40-like (n = 43), blaOXA–23-like (n = 8), and blaVIM (n = 2), as well as class 1 (n = 189) and class 2 (n = 12) integrons. One extensively drug-resistant Klebsiella pneumoniae strain (sequence type ST39 and capsular type K23), simultaneously carried beta-lactamase genes, blaSHV–40 and blaTEM–1B, three carbapenemase genes, blaNDM, blaKPC, and blaOXA–48, the cephalosporinase gene blaCTX–M, and two class 1 integrons. Before this study, such heavily armed strains have not been reported, suggesting the ongoing evolution of antibiotic resistance