Effect of ceramic-based coatings deposited on low-alloyed steel T/P22 10H2M exposed at high temperature

The study was carried out in order to evaluate oxidation resistance of the ceramic coatings based on SiO₂-B₂O₃-TiO₂-Na₂O composition deposited on the low-alloyed steel T/P22 (10H2M) surface exposed for 1000 h at 540°C in oxidation atmosphere. Kinetic data were recorded periodically every 250 h; macro- and microanalyses as well as chemical composition were carried out using macrolenses, SEM, EDS, EDS X-ray mappings. The results indicated a high degree of protection by ceramic coatings; much lower mass gain was observed for the coated materials than for the uncoated T/P22 (10H2M) steel. No detachment, delamination, chipping of a coating were found from the steel surface; some of the coatings showed perpendicular tiny cracks to the bulk metal surface.     

Intensification of biogas production using various technologies: A review

Anaerobic digestion (AD) is an organic matter conversion technology which offers a wide range of options for production of biogas from organic biomass, providing an excellent opportunity to convert abundant bioresources into safe, eco-friendly, renewable energy. Important factors in the process of AD are the biodiversity of microorganisms, chemical load of oxygen demand, and content of water and total solids. A challenge for the future is to find technologies that will maximally enhance biogas production and to find pathways for biogas to supersede well-established technologies and practices in the contemporary heavily fossil fuel-based energy system. Current studies on technologies of biogas production indicate a number of possibilities of using appropriate biological and physicochemical additives, like added enzymes or fruit pomace, as well as immobilizing microorganisms on biofilters. Anaerobic biorefinery is an emerging concept that generates not only bioenergy but also high-value biochemical products from the same feedstock. This study is a review of articles describing the intensification of biogas production by using various technologies.     

Chronic Low Grade Inflammation in Pathogenesis of PCOS

Polycystic ovary syndrome (PCOS) is a one of the most common endocrine disorders, with a prevalence rate of 5–10% in reproductive aged women. It’s characterized by (1) chronic anovulation, (2) biochemical and/or clinical hyperandrogenism, and (3) polycystic ovarian morphology. PCOS has significant clinical implications and can lead to health problems related to the accumulation of adipose tissue, such as obesity, insulin resistance, metabolic syndrome, and type 2 diabetes. There is also evidence that PCOS patients are at higher risk of cardiovascular diseases, atherosclerosis, and high blood pressure. Several studies have reported the association between polycystic ovary syndrome (PCOS) and low-grade chronic inflammation. According to known data, inflammatory markers or their gene markers are higher in PCOS patients. Correlations have been found between increased levels of C-reactive protein (CRP), interleukin 18 (IL-18), tumor necrosis factor (TNF-α), interleukin 6 (IL-6), white blood cell count (WBC), monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1α (MIP-1α) in the PCOS women compared with age- and BMI-matched controls. Women with PCOS present also elevated levels of AGEs and increased RAGE (receptor for advanced glycation end products) expression. This chronic inflammatory state is aggravating by obesity and hyperinsulinemia. There are studies describing mutual impact of hyperinsulinemia and obesity, hyperandrogenism, and inflammatory state. Endothelial cell dysfunction may be also triggered by inflammatory cytokines. Many factors involved in oxidative stress, inflammation, and thrombosis were proposed as cardiovascular risk markers showing the endothelial cell damage in PCOS. Those markers include asymmetric dimethylarginine (ADMA), C-reactive protein (CRP), homocysteine, plasminogen activator inhibitor-I (PAI-I), PAI-I activity, vascular endothelial growth factor (VEGF) etc. It was also proposed that the uterine hyperinflammatory state in polycystic ovary syndrome may be responsible for significant pregnancy complications ranging from miscarriage to placental insufficiency. In this review, we discuss the most importance evidence concerning the role of the process of chronic inflammation in pathogenesis of PCOS.     

Kinetics of commercial olive oil oxidation: Dynamic differential scanning calorimetry and Rancimat studies

Four samples of olive oil were oxidized under polythermal (dynamic) conditions in the cell of a normal‐pressure differential scanning calorimeter (DSC) and in the Metrohm Rancimat apparatus. The DSC experiments were carried out in an oxygen flow atmosphere using different linearly programmed heating rates in the range of 4–20 °C/min. Through DSC exotherms, the extrapolated onset temperatures were determined and used for the assessment of the thermal‐oxidative stabilities of the samples. Using the Ozawa‐Flynn‐Wall method and the Arrhenius equation, the activation energies (E_a), pre‐exponential factors (Z) and reaction rate constants (k) for oil oxidation under DSC conditions were calculated. The Rancimat measurements of oxidation induction times were carried out under isothermal conditions in an air atmosphere at temperatures from 100 to 140 °C with intervals of 10 °C. Using the Arrhenius‐type correlation between the inverse of the induction times and the absolute temperature of the measurements, E_a, Z, and k for oil oxidation under Rancimat conditions were calculated. The primary kinetic parameters derived from both methods were qualitatively consistent and they help to evaluate the oxidative stabilities of oils at increased temperatures.     

Interference compensation for thin layer coulometric ion-selective membrane electrodes by the double pulse technique

Ion-selective membranes operated in a thin layer coulometric detection mode have previously been demonstrated to exhibit attractive characteristics in view of realizing sensors without the need for frequent recalibration. In this methodology, the analyte ion is exhaustively removed across an ion-selective membrane by an applied potential, and the resulting current is integrated to yield the coulomb number and hence the amount of analyte originally present in the sample. This exhaustive process, however, places greater demands on the selectivity of the membrane compared to direct potentiometry, since the level of interference will increase as the analyte depletes. We evaluate here a double pulse protocol to reduce the level of interference, in which the sample is electrolyzed once again after the initial coulometric detection pulse. Since the analyte ion is no longer present at significant concentrations during the second pulse, but an interfering ion of high concentration did not appreciably deplete, the second electrolysis step may be used to partially compensate for undesired interference. These processes are here evaluated by numerical simulation for ions of the same charge, demonstrating that the resulting coulomb number may indeed be reduced for systems of limited selectivity. The improvement in operational selectivity relative to uncompensated coulometry is found to be ca. 6-fold. The methodology is successfully demonstrated experimentally with a calcium selective membrane and tetraethylammonium as a model interfering agent, and the observed relative errors after background compensation can be favorably compared to that in direct potentiometry where no sample depletion occurs.     

Coulometric sodium chloride removal system with Nafion membrane for seawater sample treatment

Seawater analysis is one of the most challenging in the field of environmental monitoring, mainly due to disparate concentration levels between the analyte and the salt matrix causing interferences in a variety of analytical techniques. We propose here a miniature electrochemical sample pretreatment system for a rapid removal of NaCl utilizing the coaxial arrangement of an electrode and a tubular Nafion membrane. Upon electrolysis, chloride is deposited at the Ag electrode as AgCl and the sodium counterions are transported across the membrane. This cell was found to work efficiently at potentials higher than 400 mV in both stationary and flow injection mode. Substantial residual currents observed during electrolysis were found to be a result of NaCl back diffusion from the outer side of the membrane due to insufficient permselectivity of the Nafion membrane. It was demonstrated that the residual current can be significantly reduced by adjusting the concentration of the outer solution. On the basis of ion chromatography results, it was found that the designed cell used in flow injection electrolysis mode reduced the NaCl concentration from 0.6 M to 3 mM. This attempt is very important in view of nutrient analysis in seawater where NaCl is a major interfering agent. We demonstrate that the pretreatment of artificial seawater samples does not reduce the content of nitrite or nitrate ions upon electrolysis. A simple diffusion/extraction steady state model is proposed for the optimization of the electrolysis cell characteristics.     

Mathematical and numerical model of solidification process of pure metals

This paper concerns the mathematical and numerical modeling of solidification process of pure metals. Such process takes place without development of “mushy zone”, which very often occurs during solidification of alloys. The model is based on the finite element method (FEM) and takes into account the existence of a sharp solidification front which moves according to time. The paper discusses how to include the conditions of continuity on the moving interface as well as the technique of front tracking based on the level set method (LSM). The paper also presents the results of computer simulations of the solidification process of pure copper. Two in-home solvers for one- and two-dimensional problems were built. Both of them are based on FEM. The correctness of the front tracking technique was checked by comparing the results obtained from 2D simulation to 1D simulation. Furthermore, the final calculation process was done for the two-dimensional area at different temperatures on the boundaries to demonstrate the effectiveness of the solver for a complex shape of the solidification front.     

Molecular Mechanisms of Chemoresistance Induced by Cisplatin in NSCLC Cancer Therapy

Cancer cells utilise several mechanisms to increase their survival and progression as well as their resistance to anticancer therapy: deregulation of growth regulatory pathways by acquiring grow factor independence, immune system suppression, reducing the expression of antigens activating T lymphocyte cells (mimicry), induction of anti-apoptotic signals to counter the action of drugs, activation of several DNA repair mechanisms and driving the active efflux of drugs from the cell cytoplasm, and epigenetic regulation by microRNAs (miRNAs). Because it is commonly diagnosed late, lung cancer remains a major malignancy with a low five-year survival rate; when diagnosed, the cancer is often highly advanced, and the cancer cells may have acquired drug resistance. This review summarises the main mechanisms involved in cisplatin resistance and interactions between cisplatin-resistant cancer cells and the tumour microenvironment. It also analyses changes in the gene expression profile of cisplatin sensitive vs. cisplatin-resistant non-small cell lung cancer (NSCLC) cellular model using the {"type":"entrez-geo","attrs":{"text":"GSE108214","term_id":"108214"}}GSE108214 Gene Expression Omnibus database. It describes a protein-protein interaction network that indicates highly dysregulated TP53, MDM2, and CDKN1A genes as they encode the top networking proteins that may be involved in cisplatin tolerance, these all being upregulated in cisplatin-resistant cells. Furthermore, it illustrates the multifactorial nature of cisplatin resistance by examining the diversity of dysregulated pathways present in cisplatin-resistant NSCLC cells based on KEGG pathway analysis.