Thermodynamic analysis of environmental problems of energy

The paper discusses the problems of the ecological analysis of physicochemical processes in power units and the impact of energy systems on the nature in large territorial regions. The model of extreme intermediate states developed at the Energy Systems Institute based on the principles of classical equilibrium thermodynamics was chosen to devise specific computational methods. The results of the conducted studies are presented and directions for further work are outlined

Thermodynamic Tree: The Space of Admissible Paths

Is a spontaneous transition from a state x to a state y allowed by thermodynamics? Such a question arises often in chemical thermodynamics and kinetics. We ask the more formal question: is there a continuous path between these states, along which the conservation laws hold, the concentrations remain non-negative and the relevant thermodynamic potential G (Gibbs energy, for example) monotonically decreases? The obvious necessary condition, G(x)\geq G(y), is not sufficient, and we construct the necessary and sufficient conditions. For example, it is impossible to overstep the equilibrium in 1-dimensional (1D) systems (with n components and n-1 conservation laws). The system cannot come from a state x to a state y if they are on the opposite sides of the equilibrium even if G(x) > G(y). We find the general multidimensional analogue of this 1D rule and constructively solve the problem of the thermodynamically admissible transitions. We study dynamical systems, which are given in a positively invariant convex polyhedron D and have a convex Lyapunov function G. An admissible path is a continuous curve along which $G$ does not increase. For x,y from D, x\geq y (x precedes y) if there exists an admissible path from x to y and x \sim y if x\geq y and y\geq x. The tree of G in D is a quotient space D/~. We provide an algorithm for the construction of this tree. In this algorithm, the restriction of G onto the 1-skeleton of $D$ (the union of edges) is used. The problem of existence of admissible paths between states is solved constructively. The regions attainable by the admissible paths are described.Comment: Extended version, 31 page, 9 figures, 69 cited references, many minor correction

Применение магнитно-резонансной томографии у больных хроническим парапроктитом (предварительные результаты)

Aim. Investigation of possibilities of magnetic resonance imaging as a whole, as well as different modes of MR scanning (without intravenous contrast, with intravenous contrast, with the use of diffusion-weighted imaging) in the diagnosis of cryptogenic fistulas of the rectum.Materials and methods. In the study were included 50 patients with cryptogenic fistulas of the rectum (21 women and 29 men). All patients underwent magnetic resonance imaging of the pelvic organs.Results. The sensitivity of MRI in the diagnosis of the primary fistulas was 100%. With regard to secondary fistulas MRI sensitivity was 91.7%, specificity was 94.3%. The sensitivity of MRI in the diagnosis of chronic abscesses paraproctitis was 82.6%, specificity was 95.2%. The sensitivity of the method in the visualization of internal opening was 95.5%, specificity was 80.0%. The sensitivity of the method in the diagnosis of external openings was 91.7% and specificity was 100%. In the analysis of separates MR scanning mode we didn’t find statistically significant differences between them (p < 0.05). Conclusions. Magnetic resonance imaging has a high diagnostic efficacy in the diagnosis of cryptogenic perianal fistulas. We didn’t find statistically significant differences between MR scanning modes.Цель исследования: оценить возможности магнитно-резонансной томографии в целом, а также различных режимов МР-сканирования (без внутривенного контрастирования, с внутривенным контрастированием, с применением диффузионно-взвешенных изображений) в диагностике криптогенных свищей прямой кишки.Материал и методы. В исследование включено 50 пациентов с криптогенными свищами прямой кишки (21 (42,0%) женщина и 29 (58,0%) мужчин). Всем пациентам была выполнена магнитно-резонансная томография органов малого таза.Результаты. Чувствительность магнитно-резонансной томографии в диагностике основного свищевого хода составила 100%. В отношении добавочного свищевого хода чувствительность магнитно-резонансной томографии составила 91,7%, специфичность – 94,3%. Чувстви тельность магнитно-резонансной томографии в диагностике абсцессов при хроническом парапроктите составила 82,6%, специфичность – 95,2%, в визуализации внут реннего свищевого отверстия – 95,5 и 80,0% соответственно, в диагностике наружных свищевых отверстий – 91,7% и 100,0% соответственно. При анализе отдельных МР-режимов сканирования статистически значимых различий между ними выявлено не было (p < 0,05).Выводы. Магнитно-резонансная томография имеет высокую диагностическую эффективность в диагностике криптогенных свищей прямой кишки. Сравнение диагностической информативности отдельных режимов сканирования не выявило между ними статистически значимых различий

Thermodynamic analysis of environmental problems of energy

The paper discusses the problems of the ecological analysis of physicochemical processes in power units and the impact of energy systems on the nature in large territorial regions. The model of extreme intermediate states developed at the Energy Systems Institute based on the principles of classical equilibrium thermodynamics was chosen to devise specific computational methods. The results of the conducted studies are presented and directions for further work are outlined

Thermodynamic analysis of environmental problems of energy

The paper discusses the problems of the ecological analysis of physicochemical processes in power units and the impact of energy systems on the nature in large territorial regions. The model of extreme intermediate states developed at the Energy Systems Institute based on the principles of classical equilibrium thermodynamics was chosen to devise specific computational methods. The results of the conducted studies are presented and directions for further work are outlined

Conventional Hydraulic Circuits in an Analysis of Environmental Issues

The paper addresses the problems of conventional circuit modeling in an analysis of anthropogenic pollution of nature. A joint use of two types of models is proposed: 1) a model of conventional hydraulic circuits and 2) a model of extreme intermediate states developed by Melentiev Energy Systems Institute. The first model is used to calculate the distribution of pollutants in the atmosphere and their precipitation. The second model is intended for an analysis of the formation of pollutants and their transformations in branches as a result of chemical reactions and phase transitions. The analysis is based on the propositions of classical equilibrium thermodynamics. The applicability of the thermodynamic equilibrium and extremality principles and one-dimensional circuit models in the study of both reversible and irreversible processes are substantiated. Specific problems are analyzed. These are the determination of the yield of harmful substances in fuel combustion and processing, the distribution of pollutants in the atmosphere of large regions, the impact of hydro and wind power plants on the formation of harmful solutions in the air. The possibility of using a conventional graph (a thermodynamic tree) proposed by A.N. Gorban to analyze fuel technologies is demonstrated. The statement of the problem related to the assessment of the environmental compatibility of integrated energy systems is presented. The admissibility of the representation of the optimal distribution of flows in the integrated system as a sum of optimal distributions in its subsystems that differ from one another in physical-technical and economic nature is explained

Procalcitonin and C-reactive protein - early predictors of low colorectal anastomotic leakage

Aim of investigation. To determine diagnostic value of procalcitonin (PCT) and C-reactive protein (CRP) at anastomotic leakage (AL) following lower anterior resection (LAR) of the rectum. Material and methods. Overall 100 patients underwent surgery for epithelial tumors of rectum in the period 2013-2016 yy in the volume of LAR with the formation of anastomosis and preventive stoma. In patients without clinical symptoms radiopaque study was performed in order to identify asymptomatic AL on day 7 after the surgery. AL rate, difference in PCT and CRP levels in patients with AL and consistent anastomosis were assessed along with sensitivity, specificity, positive and negative predictive value of these markers. Results. AL was diagnosed in 20% (20 of 100) of patients: in 11% (11 of 100) - with clinical manifestations, in 9% (9 of 100) - without clinical symptoms (contrast leakage according to X-ray study). In the group of patients with anastomotic leak, the median of C-reactive protein level differed from that in patients with uncompromised integrity of anastomosis at 3rd day after surgery (156 mg/L vs 81 mg/L, respectively - t-test, p=0.0004) and postoperative day 6 (136 mg/L vs. 52 mg/L, respectively - t-test,