Distillation optimization: Parameterized relationship between feed flow rate of a steady-state distillation column and heat duties of reboiler and condenser

The paper considers the problem of maximum efficiency for the system of distillation columns. Columns in such systems are connected in parallel or sequential way. The mixture being separated is assumed to be close to ideal one. Authors parameterize the relationship between feed flow rate and heat duties of a steady-state binary distillation column using two parameters: the reversible efficiency and the irreversibility coefficient. This relationship is later being used to solve the problems of optimal distribution of heat and feed flows within the system. The results obtained allow one to estimate minimum heat energy demand for distillation of the given feed flow, maximum performance, and efficiency of the system. © 2022 John Wiley & Sons, Ltd.Robert Sterling Clark Foundation, RSCF: 20-61-46013This work is supported by RSCF Grant 20-61-46013

Interventions for treating depression after stroke

Background: Depression is an important consequence of stroke that impacts on recovery yet is often not detected or inadequately treated. This is an update of a Cochrane review first published in 2004. Objectives: To determine whether pharmaceutical, psychological, or electroconvulsive treatment (ECT) of depression in patients with stroke can improve outcome. Search strategy: We searched the trials registers of the Cochrane Stroke Group (last searched October 2007) and the Cochrane Depression Anxiety and Neurosis Group (last searched February 2008). In addition, we searched the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2008), MEDLINE (1966 to May 2006), EMBASE (1980 to May 2006), CINAHL (1982 to May 2006), PsycINFO (1967 to May 2006) and other databases. We also searched reference lists, clinical trials registers, conference proceedings and dissertation abstracts, and contacted authors, researchers and pharmaceutical companies. Selection criteria: Randomised controlled trials comparing pharmaceutical agents with placebo, or various forms of psychotherapy or ECT with standard care (or attention control), in patients with stroke, with the intention of treating depression. Data collection and analysis: Two review authors selected trials for inclusion and assessed methodological quality; three review authors extracted, cross-checked and entered data. Primary analyses were the prevalence of diagnosable depressive disorder at the end of treatment. Secondary outcomes included depression scores on standard scales, physical function, death, recurrent stroke and adverse effects. Main results: Sixteen trials (17 interventions), with 1655 participants, were included in the review. Data were available for 13 pharmaceutical agents, and four trials of psychotherapy. There were no trials of ECT. The analyses were complicated by the lack of standardised diagnostic and outcome criteria, and differing analytic methods. There was some evidence of benefit of pharmacotherapy in terms of a complete remission of depression and a reduction (improvement) in scores on depression rating scales, but there was also evidence of an associated increase in adverse events. There was no evidence of benefit of psychotherapy. Authors' conclusions: A small but significant effect of pharmacotherapy (not psychotherapy) on treating depression and reducing depressive symptoms was found, as was a significant increase in adverse events. More research is required before recommendations can be made about the routine use of such treatments

Pharmacoeconomic analysis of various adjunctive pharmacotherapy strategies for back pain using comparative method

Spinal disorders are one of the leading causes of disability worldwide. Back pain is one of the most important factors that reduce the patients’ quality of life. The right choice of pharmacotherapy in conjunction with other medical technologies is the key to successful treatment. In addition to drugs that relieve pain, much attention should be paid to the restoration of cartilage in the spine. This paper presents a comparative pharmacoeconomic analysis of the use of chondroitin and glucosamine as the adjunctive therapy

PHARMACOECONOMIC EVLUATION OF 5-ASA APPLICATION IN LIGHT AND MEDIUM GRAVE DISSEMINATED (RECURRING) ULCERATIVE COLITIS

Inflammatory bowel diseases are chronic relapsing immune-mediated diseases affecting the gastrointestinal tract. The goal of therapy of ulcerative colitis (one of the IBD variants) is the achievement and maintenance of steroid-free remission, prevention of UC complications, prevention of surgeries and the timely use of surgical treatment when the process progresses and lifethreatening complications develop. It Is predominantly diagnosed in young people and leads to a significant reduction of quality of life. The peculiarity of the UC is its chronic recurrent course. Work on the choice of the most rational schemes of therapy continues goes on. New data from clinical studies on the efficacy and safety of modern methods of pharmacotherapy in addition to data on pharmacoepidemiology and pharmacoeconomics should help the medical community to develop the most optimal treatment strategies based on clinical and socio-economic factors. The standard therapy in the first phase is 5-ASA preparations, such as sulfasalazine and mesalazine. Given the efficacy and safety of each of these preparations it is possible to predict the frequency of transition of patients to more difficult treatment options systemic corticosteroids and biological agents arising in connection with this the possible side effects and additional economic load on the healing process. The article presents economic assessment of the use of two alternative first-line drugs for therapy - mesalazine and sulfasalazine; it shows a possible burden on the budget and subsequent benefit when switching to the most optimal treatment option

High-temperature service life tests of full-size thermosyphons

During past two decades, at temperature 240-265°C, resource tests were carried out on 19 thermosyphons of full-scale sizes: 45х4 mm in diameter, 4.92 m in length. The thermosyphons were prepared with varying preliminary surface treatment methods, composition of the aqueous solution to be poured into the thermosyphons, location of titanium chips in the perforated capsules under the lid of the thermosyphons. With a period of 1 to 3 years, thermosyphons were removed from testing system for 30 hours to control the vacuum by thermal method that does not require depressurization. At the last control experiment, four thermosyphons are depressurized for the following purposes: to check the condition of their internal surface in different zones along the length; for the chemical analysis of the aqueous solution poured from them; to determine the structure and characteristics of the mechanical properties of the thermosyphon metal. The main aim of the tests is to justify maintaining the structure and mechanical properties of the metal for a long time, keeping a vacuum of 90-95% inside the thermosyphon, ensuring high heat transfer characteristics of the boiling operating mode of thermosyphons

Pharmacoeconomic evaluation of the use of targeted therapy and chemotherapy in the first- and second-line therapies for metastatic colorectal cancer

Colorectal cancer (CRC) is a genetically heterogeneous disease, which prognosis and efficacy of treatment are determined by the localization of the primary tumour (left- and right-sided tumours). CRC ranks high in prevalence in the Russian Federation, a quarter of cases are diagnosed at stage IV. The choice of the most optimal therapy regimen is a topical issue for a modern oncologist, who has time-proven combinations of chemotherapy and modern targeted drugs in the arsenal. The aim of this article is to provide a pharmacoeconomic review, taking into account both clinical and economic parameters of one or another CRC pharmacotherapy regimen. As a result, it was found that the use of chemotherapeutic regimens in the first- and second-line therapies of patients with CRC is the most pharmacoeconomically justified as compared with the use of targeted therapy at the initial stage

Entropic Balance Conditions and Optimization of Distillation Column System

The paper considers the limitation problem of the distillation column systems separating multicomponent mixtures with serial and parallel structures. The solution takes into account the irreversibility of processes. Using entropic balance conditions, the dependence of load on heat consumption is obtained for a binary distillation column. This dependence is parameterized through two characteristic coefficients–reversible efficiency and irreversibility factor. This dependence was used to solve problems of distribution of heat and raw material fluxes in parallel column structure and selection of optimal separation order in serial structure. The obtained results make it possible to estimate the minimum heat consumption for the separation of a given flow of raw materials, the maximum productivity, and efficiency of the system

Optimal Control of Technological Processes

The paper formulates conditions under which the roots closest to the imaginary axis (critical roots) of the characteristic equation of a linearized system are real for the maximum possible degree of stability of the closed-loop control system of a technological process with pure delay. For the parameters of the controllers corresponding to the maximum degree of stability, these roots are multiples. Their multiplicity order is one more than the number of coefficients in the transfer function of the controller. It is demonstrated that for a typical technological control object, these conditions are satisfied for all “serial” control laws. This allowed for obtaining analytical expressions for optimal settings and limiting degrees of stability as functions of object parameters for typical dynamic characteristics of technological processes. The paper considers the problem of robust stability for control systems with an object containing pure delay. It has been proven that in the maximum stability problem, the operations of maximizing over controller parameters and minimizing over the set of possible object parameters can be interchanged. Therefore, selecting robust settings amounts to determining the minimum of the maximum stability over the set of possible object parameter values. Controllers with such settings are suitable, without modification, for a whole class of technological processes