On the accuracy of CFD modeling of cyclic high heat flux divertor experiment

To investigate the heat removal capability of conceptual divertor cooling fingers, accurate computational fluid dynamics (CFD) analyses are indispensable. Although the cooling performance of the divertor finger has been successfully high-heat-flux tested under real DEMO conditions in a combined helium loop and electron beam facility at the Efremov Institute, Russia, an accompanying numerical simulation of the experiments is of great importance. This might help to better understand the complex thermo-hydraulic conditions with the aim of predicting other different load cases. To accurately reproduce the experimental boundary conditions, the Gaussian-like shape of the absorbed power was taken into account and the heat losses were estimated. Modeling of the structure thermal conductivity was also found to be an important source of modeling uncertainty. In the context of accurate modeling of experimental conditions, the effect of some modeling assumptions was evaluated. Transient simulations of the cyclic heat flux experiment were performed only for the solid part of the cooling finger to avoid excessively long computation times. The helium cooling was taken into account by the heat transfer coefficient (HTC) on the fluid–structure interface, obtained from the steady-state simulations of the full solid–fluid model. The HTC distribution did not vary with time throughout the entire transient simulation. The modeling error associated with such HTC approximation was estimated for the particular cyclic experiment. It is shown that the simulated temperature cycles on the top of experimental mock-up agree well with the measured data.     

Biogenesis of acetylcholinesterase is impaired, although its mRNA level remains normal, in the glucocorticoid-treated rat skeletal muscle

Acetylcholinesterase (AChE) is responsible for the hydrolysis of acetylcholine in the neuromuscular junction and other cholinergic synapses. Insight into the mechanisms controlling AChE expression in skeletal muscle is important for understanding formation, plasticity, and various dysfunctions of the neuromuscular junction. We have investigated the mechanisms responsible for the decreased AChE activity in the fast rat sternomastoideus muscle after chronic glucocorticoid treatment. Under such conditions fast skeletal muscles become atrophic and loose 30-40% of their AChE activity. In order to establish at which level synthesis of AChE is affected by glucocorticoids, we studied the effects of chronic dexamethasone treatment at both AChE mRNA and mature enzyme levels. Reduced rate of AChE recovery after subtotal irreversible AChE inhibition was observed during the first week of dexamethasone treatment, but not later. Statistical analyses of four independent northern blots revealed unchanged AChE mRNA levels. At the same time, we observed more than 60% decrease in the (G1+G2)/A12 ratio of molecular forms at the expense of G forms. It has been generally accepted that globular G1 and G2 molecular forms are synthesized in the rough endoplasmic reticulum as precursors of asymmetric (A) AChE forms, assembled in the Golgi apparatus. Reduced levels of G1 and G2 AChE forms, in combination with unchanged AChE mRNA, are therefore consistent with the reports demonstrating that glucocorticoids downregulate muscle protein synthesis at the translational level. Our findings support but not entirely prove the concept that impaired translation and/or posttranslational control are the primary cause of decreased AChE activity in the glucocorticoid-treated muscle.     

Pattern recognition-based supervision of indirect adaptation for better disturbance handling

An advanced pattern recognition-based supervision algorithm for an indirect adaptive controller is proposed. The aim is to improve performance under certain conditions that are common in the industrial environment, in which indirect adaptive controllers with simple supervision are known to perform poorly or unreliably. Specifically, the problem of large invasive unmeasured disturbances of short or longer duration is addressed. The supervisor is designed to recognize such events as quickly as possible by analysis of recent control signals, without additional measurements. It applies appropriate strategies to prevent model degradation by learning from misleading data and to maintain acceptable performance under unfavorable conditions. As an illustration, it has been applied to the control of a model of a semi-cleanroom HVAC installation subsystem.     

The Cytotoxic Activity of Macromolecular Ferrocene Conjugates Against the Colo 320 DM Human Colon Cancer Line

Water-soluble and biocompatible polymers containing bioreversibly attached ferrocene units as side chain terminals have in recent years attracted interest in drug research. In preliminary screens, polymers of this type have shown high antiproliferative activity against selected human carcinoma cell lines, paired with low in vivo toxicity. They may thus lend themselves as efficacious prodrugs in cancer chemotherapy. Cancers of the intestinal system are known to resist chemotherapeutic treatment. This general lack of sensitivity of the colorectal malignancies prompted us to investigate the in vitro behavior of selected carrier-bound ferrocene prodrugs against the Colo 320 DM cell line, a representative human adenocarcinoma of the colon. The findings of this investigation are reported in the present communication. The carriers 1 to 10 used for conjugation with the metallocene are water-soluble aliphatic polyamides featuring primary or secondary amine functionality as side chain terminals or main chain constituents. By previously developed methodology these amino groups are coupled with the ferrocenylation agent, 4-ferrocenylbutanoic acid, generating the target conjugates 1-Fc to 10-Fc, in which the metallocene is bound through amide or hydrazone links. Cell culture tests are performed by established protocol against the Colo line and, for comparison, also against the HeLa cells. Significantly, while outstanding performance is observed for most of the conjugates against both cell lines, the results indicate activities in the Colo screens to be higher on average than determined in the sensitive HeLa tests.     

Antimicrobial and antioxidative enrichment of oak (Quercus robur) bark by rotation planar extraction using ExtraChrom

The multifunctional ExtraChrom instrument was used in the extraction of antimicrobial and radical scavenging components from oak (Quercus robur L.) bark. Milled and sieved oak bark was extracted with 80% (v/v) methanol solution in water on the ExtraChrom instrument using step-gradient in the preparative separation. Extracts were tested using agar diffusion method on Staphylococcus aureus, Enterobacter aerogenes and Candida albicans. Some extracts showed moderate bactericidal, fungicidal, bacteriostatic and fungistatic activity. The composition related to activity of the fractions and extracts was screened simultaneously by thin-layer chromatography (TLC) detected by UV and by spraying the plate with radical scavenging reagent 1,1-diphenyl-2-picrylhydrazyl (DPPH) to detect antioxidant activity. Thus, we could demonstrate the antiradical and antimicrobial activity of oak beneficial in the storage of wine against the oxidation and human microbial exposure.     

Diagnostics of anodic stripping mechanisms under square-wave voltammetry conditions using bismuth film substrates

A mechanistic study to provide diagnostics of anodic stripping electrode processes at bismuth-film electrodes is presented from both theoretical and experimental points of view. Theoretical models for three types of electrode mechanisms are developed under conditions of square-wave voltammetry, combining rigorous modeling based on integral equations and the step function method, resulting in derivation of a single numerical recurrent formula to predict the outcome of the voltammetric experiment. In the course of the deposition step, it has been assumed that a uniform film of the metal analyte is formed on the bismuth substrate, in situ deposited onto a glassy carbon electrode surface, without considering mass transfer within either the bismuth or the metal analyte film. Theoretical data are analyzed in terms of dimensionless critical parameters related with electrode kinetics, mass transfer, adsorption equilibria, and possible lateral interactions within the deposited metal particles. Theoretical analysis enables definition of simple criteria for differentiation and characterization of electrode processes. Comparing theoretical and experimental data, anodic stripping processes of zinc(II), cadmium(II), and lead(II) are successfully characterized, revealing significant differences in their reaction pathways. The proposed easy-to-perform diagnostic route is considered to be of a general use while the bismuth film exploited in this study served as a convenient nonmercury model substrate surface.     

Reactivity at the film/solution interface of ex situ prepared bismuth film electrodes: A scanning electrochemical microscopy (SECM) and atomic force microscopy (AFM) investigation

Bismuth film electrodes (BiFEs) prepared ex situ with and without complexing bromide ions in the modification solution were investigated using scanning electrochemical microscopy (SECM) and atomic force microscopy (AFM). A feedback mode of the SECM was employed to examine the conductivity and reactivity of a series of thin bismuth films deposited onto disk glassy carbon substrate electrodes (GCEs) of 3 mm in diameter. A platinum micro-electrode (? = 25 μm) was used as the SECM tip, and current against tip/substrate distance was recorded in solutions containing either Ru(NH₃)₆³⁺ or Fe(CN)₆⁴⁻ species as redox mediators. With both redox mediators positive feedback approach curves were recorded, which indicated that the bismuth film deposition protocol associated with the addition of bromide ions in the modification solution did not compromise the conductivity of the bismuth film in comparison with that prepared without bromide. However, at the former Bi film a slight kinetic hindering was observed in recycling Ru(NH₃)₆³⁺, suggesting a different surface potential. On the other hand, the approach curves recorded by using Fe(CN)₆⁴⁻ showed that both types of the aforementioned bismuth films exhibited local reactivity with the oxidised form of the redox mediator, and that bismuth film obtained with bromide ions exhibited slightly lower reactivity. The use of SECM in the scanning operation mode allowed us to ascertain that the bismuth deposits were uniformly distributed across the whole surface of the glassy carbon substrate electrode. Comparative AFM measurements corroborated the above findings and additionally revealed a denser growth of smaller bismuth crystals over the surface of the substrate electrode in the presence of bromide ions, while the crystals were bigger but sparser in the absence of bromide ions in the modification solution.     

The effect of epidermal growth factor and transforming growth factor beta 1 on proliferation and differentiation of urothelial cells in urinary bladder explant culture

The presence of the virulence markers K1 capsule, serum resistance, aerobactin, S and P/PR fimbriae were examined in a total of 395 E. coli strains from different extraintestinal infections and in 81 faecal isolates of healthy volunteers using specific DNA probes and classical phenotypic methods. All markers were more frequently detected when genotypic assays were applied. The simultaneous occurrence of 3-4 virulence determinants was typical for isolates derived from patients with septicaemia or meningitis. Isolates from blood cultures and cerebrospinal fluid were expressing the virulence phenotypes to a greater extent than isolates from urine or faeces. The use of colony hybridization with specific oligonucleotide and polynucleotide probes for the detection of virulence determinants has been proven to be more specific and reliable than phenotypic approaches.     

Modes of Exocytotic and Endocytotic Events in Tobacco BY-2 Protoplasts

To analyze the kinetics and size of single exo- and endocytotic events in BY-2 protoplasts,we employed cell-attached membrane capacitance measurements. These measurements revealed different modes of fusion and fission of single vesicles. In about half of the observed exocytotic events,fusion occurred transiently,which facilitates rapid recycling of vesicles. In addition,transient sequential or multi-vesicular exocytosis observed in some recordings can contribute to an increase in efficiency of secretory product release. Microscopic analysis of the timescale of cellulose and pectin deposition in protoplasts demonstrates that rebuilding of the cell wall starts soon after isolation of protoplasts and that transient fusion events can fully account for secretion of the required soluble material. The capacitance measurements also allowed us to investigate formation of the fusion pore. We speculate that regulation of secretion may involve control of the length and/or size of fusion pore opening. Together,the different kinetic modes of exo- and endocytosis revealed by capacitance measurements underline the complexity of this process in plants and provide a basis for future research into the underlying mechanisms. The fact that similar fusion/fission kinetics are present in plant and animal cells suggests that many of these mechanisms are highly conserved among eukaryotes.