Injection of water into a porous medium saturated with steam

This paper deals with injection of water into heated porous media saturated with steam. It is assumed that phase transformations occur entirely on the frontal surface which separates regions filled with water and steam. Two modes of injection are possible. In the first mode, which is realized at rather substantial differences between the initial temperature of the reservoir and the temperature of water being injected, the condensation of steam occurs at the interface. In so doing, the pressure at the interface becomes lower than the initial reservoir pressure, and, as a result, a minimum of pressure distribution occurs. The second mode, on the contrary, involves the evaporation of water being injected. The criterion used to distinguish between these two modes is determined. The critical condition is derived for the case when the temperature evolution in the region of percolation of liquid is largely defined by convective transfer. In so doing, the temperature distribution has three uniform domains with values equal to those of the temperature of liquid being injected, of the initial temperature of the porous medium, and of some intermediate temperature equal to the temperature at the interface, and the temperature differences in the porous medium are realized in two layers. The first of these layers is in the vicinity of the interface, and the second one, in the zone of percolation of water. For this case, which is realized at fairly significant pressure drops and a high permeability of the reservoir, self-similar solutions are constructed for plane and radially symmetric problems.     

Biofuel Production: A Promising Direction for Reducing Carbon Footprint in the Transition to Green Energy

Chemistry and Technology of Fuels and Oils - The article presents the measures of state regulation of the European Union countries to create incentives to reduce the carbon footprint. Information...     

The “Angiogenic Switch” and Functional Resources in Cyclic Sports Athletes

Regular physical activity in cyclic sports can influence the so-called “angiogenic switch”, which is considered as an imbalance between proangiogenic and anti-angiogenic molecules. Disruption of the synthesis of angiogenic molecules can be caused by local changes in tissues under the influence of excessive physical exertion and its consequences, such as chronic oxidative stress and associated hypoxia, metabolic acidosis, sports injuries, etc. A review of publications on signaling pathways that activate and inhibit angiogenesis in skeletal muscles, myocardium, lung, and nervous tissue under the influence of intense physical activity in cyclic sports. Materials: We searched PubMed, SCOPUS, Web of Science, Google Scholar, Clinical keys, and e-LIBRARY databases for full-text articles published from 2000 to 2020, using keywords and their combinations. Results: An important aspect of adaptation to training loads in cyclic sports is an increase in the number of capillaries in muscle fibers, which improves the metabolism of skeletal muscles and myocardium, as well as nervous and lung tissue. Recent studies have shown that myocardial endothelial cells not only respond to hemodynamic forces and paracrine signals from neighboring cells, but also take an active part in heart remodeling processes, stimulating the growth and contractility of cardiomyocytes or the production of extracellular matrix proteins in myofibroblasts. As myocardial vascularization plays a central role in the transition from adaptive heart hypertrophy to heart failure, further study of the signaling mechanisms involved in the regulation of angiogenesis in the myocardium is important in sports practice. The study of the “angiogenic switch” problem in the cerebrovascular and cardiovascular systems allows us to claim that the formation of new vessels is mediated by a complex interaction of all growth factors. Although the lungs are one of the limiting systems of the body in cyclic sports, their response to high-intensity loads and other environmental stresses is often overlooked. Airway epithelial cells are the predominant source of several growth factors throughout lung organogenesis and appear to be critical for normal alveolarization, rapid alveolar proliferation, and normal vascular development. There are many controversial questions about the role of growth factors in the physiology and pathology of the lungs. The presented review has demonstrated that when doing sports, it is necessary to give a careful consideration to the possible positive and negative effects of growth factors on muscles, myocardium, lung tissue, and brain. Primarily, the “angiogenic switch” is important in aerobic sports (long distance running). Conclusions: Angiogenesis is a physiological process of the formation of new blood capillaries, which play an important role in the functioning of skeletal muscles, myocardium, lung, and nervous tissue in athletes. Violation of the “angiogenic switch” as a balance between proangiogenic and anti-angiogenic molecules can lead to a decrease in the functional resources of the nervous, musculoskeletal, cardiovascular, and respiratory systems in athletes and, as a consequence, to a decrease in sports performance.     

Candidate Genes and Proteomic Biomarkers of Serum and Urine in Medication-Overuse Headache

Chronic headache is a topical problem of neurology, psychiatry and general practice. The medication-overuse headache (MOH) is one of the leading pathologies in the structure of chronic headache. However, early diagnosis of the MOH is challenging. We analyzed potential proteomic biomarkers of serum and urine in patients with MOH. Methods: We searched PubMed, Springer, Scopus, Web of Science, ClinicalKey, and Google Scholar databases for English publications over the past 10 years using keywords and their combinations. Results: We found and analyzed seven studies that met the search criteria for the purpose of the review, including 24 serum proteomic biomarkers and 25 urine proteomic biomarkers of MOH. Moreover, the candidate genes and locus of the studied serum (vitamin D-binding protein, lipocalin-type prostaglandin D2 synthase, apolipoprotein E, etc.) and urine proteomic biomarkers (uromodulin, alpha-1-microglobulin, zinc-alpha-2-glycoprotein, etc.) of MOH are presented in this review. Conclusions: The serum and urine proteomic biomarkers of MOH can potentially help with the identification of patients with MOH development. Due to the relevance of the problem, the authors believe that further investigation of the MOH proteomic biomarkers in different ethnic and racial groups of patients with primary headache is necessary. In addition, it is important to investigate whether medications of different drug classes influence the levels of serum and urine proteomic biomarkers.     

气相色谱法测定黄瓜中丙溴磷农药残留量的测量不确定度评定

为评定检测方法NY/T 761-2008处理的黄瓜中丙溴磷农药残留检测结果的测量不确定度,找出对测量不确定度影响大的因素,规范实验操作,提高检测结果的准确性,本文通过外部加标,建立数学模型,从量器使用、标准工作液配制、重复性测量等各个分量进行评定。结果表明,丙溴磷残留量0.45 mg/kg,其扩展标准不确定度0.04 mg/kg,对测量不确定度有显著贡献的有三个方面:标准物质纯度的相对标准不确定度2%;使用6次移液器产生的相对标准不确定度2.661%;标准曲线拟合的相对标准不确定度1.615%。因此,在检测中,建议购买纯度在98.6%以上的标准溶液,做好贮存和期间核查;在配制标准工作液时,减少使用移液器的频次或使用更精密的量器且定期做好校准;按时做好测量仪器的检定和期间核查。     

Thermal Shock under the Action of Radiation Energy on a Porous Medium Partially Filled with Gas Hydrate

Consideration has been given to the process of decomposition of a gas hydrate saturating a porous volume under the action of the energy of radiation through its boundary. It has been adopted that the zone lying in the vicinity of the boundary and saturated with the products of decomposition of the gas hydrate is transparent to radiation; the far zone saturated with gas hydrate and gas, conversely, is completely opaque; therefore, the radiation energy is totally absorbed at the boundary of phase transitions between the zones mentioned. The selfsimilar solutions of plane onedimensional and radialsymmetric problems have been constructed. The influence of the radiation intensity and of the parameters of the porous medium–solid gas hydrate–gas system in the initial state on the maximum pressures produced in the zone of decomposition of the gas hydrate has been analyzed based on the analytical solutions obtained.     

Inhibition of AKT-Signaling Sensitizes Soft Tissue Sarcomas (STS) and Gastrointestinal Stromal Tumors (GIST) to Doxorubicin via Targeting of Homology-Mediated DNA Repair

Activation of the phosphoinositide 3-kinase (PI3K)/Akt/mTOR pathway is well documented for a broad spectrum of human malignancies supporting their growth and progression. Accumulating evidence has also implicated AKT as a potent modulator of anti-cancer therapies via regulation of DNA damage response and repair (DDR) induced by certain chemotherapeutic agents and ionizing radiation (IR). In the present study, we examined the role of AKT signaling in regulating of Rad51 turnover and cytotoxic effects of topoisomerase II inhibitor, doxorubicin (Dox) in soft tissue sarcomas (STS) and gastrointestinal stromal tumors (GIST) in vitro. Blocking of AKT signaling (MK-2206) enhanced cytotoxic and pro-apoptotic effects of Dox in vast majority of STS and GIST cell lines. The phosphorylated form of Akt co-immunoprecipitates with Rad51 after Dox-induced DNA damage, whereas Akt inhibition interrupts this interaction and decreases Rad51 protein level by enhancing protein instability via proteasome-dependent degradation. Inhibition of Akt signaling in Dox-treated cells was associated with the increased number of γ-H2AX-positive cells, decrease of Rad51 foci formation and its colocalization with γ-H2AX foci, thereby revealing unsuccessful DDR events. This was also in consistency with an increase of tail moment (TM) and olive tail moment (OTM) in Dox-treated GIST and STS cells cultured in presence of Akt inhibitor after Dox washout. Altogether, our data illustrates that inhibition of AKT signaling is STS and GIST might potentiate the cytotoxic effect of topoisomerase II inhibitors via attenuating the homology-mediated DNA repair.     

Novel integrated helium extraction and natural gas liquefaction process configurations using absorption refrigeration and waste heat

Conceptual design and modeling of novel-integrated process configurations for helium extraction and natural gas liquefaction is investigated. Mixed fluid cascade (MFC) refrigeration system is considered for providing the needed refrigeration in the natural liquefaction section. Using an absorption refrigeration system as the precooling cycle is investigated in one of the introduced processes. Integrated flash and distillation method is used for helium extraction. Purity of the extracted crude helium is 50% (mole). Process streams operational condition and specifications of the devices are presented and explained. Composite curves of the heat exchangers demonstrate that thermal design has been done properly. Ratio of the power consumption to the produced liquefied natural gas (LNG) of the MFC process is 0.265 kWh per kg LNG and applying absorption refrigeration system instead of the pre-cooling cycle decreases it to 0.1849 kWh per kg LNG. For the modified process with absorption refrigeration system helium extraction rate and power consumption ratio are 0.951 and 132.9 (kWh/[kgmole Helium]) respectively. Exergy method is applied on the under consideration processes. The results show that the compressors have the highest rate of exergy destruction among the other process equipment. An extensive economic analysis is done on the proposed processes. The results show that prime cost of the product (US$/kg LNG) for MFC and modified MFC processes are 0.1939 and 0.2069, respectively. Finally, a sensitivity analysis is done based on the economic factors such as electrical energy price and prime cost of the product.     

On the theory of injection of moist steam into a porous medium

A plane one-dimensional problem on the injection of moist steam into a porous medium is treated. An investigation is performed of the effect of the parameters, which define the initial state of the porous medium, boundary pressure, temperature, and moisture content of steam, on the rate of propagation of hydrodynamic and temperature fields in the porous medium.Translated from Teplofizika Vysokikh Temperatur, Vol. 42, No. 6, 2004, pp. 938–946.Original Russian Text Copyright © 2004 by V. Sh. Shagapov, I. R. Rakhmatullin, and L. A. Nasyrova.