Markedly compressible behaviors of gellan hydrogels in a constrained geometry at ultraslow strain rates

The fracture behaviors of gellan hydrogels under compression remarkably depend on the strain rate as well as the boundary conditions for lateral expansion. In the geometry with no constraint for lateral expansion (conventional uniaxial compression), the gels rupture at relatively small strains independently of the compression rates. In contrast, when the gels are compressed extremely slowly (at a strain rate of ca. 10⁻⁵ s⁻¹) in the geometry prohibiting the lateral expansion at their top and bottom surfaces, they are remarkably compressible down to 2% of the initial height without macroscopic fracture and they are accompanied by a large amount of water release. In such markedly compressed gels, many microscopic cracks are formed around the central layer, where strain concentration occurs due to the nonuniform deformation arising from the constrained geometry. In the highly compressible case, the formation of macroscopic cracks is prevented by the localization of microscopic cracks as well as the enhancement in mechanical toughness by a significant increase in polymer concentration due to water release.     

Cooperative Control by System Voltage Control Equipments in Consideration of Reducing Capacity of STATCOM

In recent years, the number of renewable energy sources (RESs) such as photovoltaic generation systems and wind power generation systems connected to the grid has been increasing as a way of reducing negative effects on the environment. The outputs of these RESs vary rapidly because of the influence of the weather and the conditions of the location. Therefore, there are concerns that the point voltages in a distribution system may vary drastically and that the voltages may deviate from the appropriate voltage range as a result of the influence of the RES connected to the distribution system or to the diversification of loads. Furthermore, there are concerns about adverse effects on electric power quality, such as voltage imbalances and harmonics. In this paper, we propose a cooperative voltage control method for a distribution system using system voltage control equipment in order to reduce the capacity of the static synchronous compensator. Numerical calculations were performed in order to verify the validity of the proposed method.     

Age correlation of the time lag in signal change on EPI-fMRI

Rifampicin synoviorthesis has been empirically used for the treatment of haemophilic synovitis for some time. This paper reports on the experience of three Latin American centers with this treatment and compares it with radioactive synoviorthesis results. Chemical synoviorthesis with rifampicin is best indicated in younger patients (< 15 years) and small joint (ankles and elbows).     

Evidence for heme-mediated redox regulation of human cystathionine beta-synthase activity

Human cystathionine beta-synthase catalyzes the first step in the catabolic removal of the toxic metabolite, homocysteine. It is unique in being dependent on both pyridoxal phosphate (PLP) and heme for activity. The reaction involves condensation of serine and homocysteine to give cystathionine. Although the role of PLP can be rationalized in analogy with other PLP-dependent enzymes that catalyze beta-replacement reactions, the role of the heme is unknown. In this study, we have purified and characterized the recombinant human enzyme and have examined the effect of heme oxidation state on enzyme activity. We find that under reducing conditions, generated by addition of titanium citrate, the enzyme exhibits a 1.7-fold lower activity than under oxidizing conditions. Reoxidation of the ferrous enzyme with ferricyanide results in alleviation of inhibition. This redox-linked change in enzyme activity correlates with changes in heme oxidation state monitored by UV-visible spectroscopy. Dithiothreitol, which does not reduce the enzyme-bound heme, does not perturb enzyme activity. These studies provide the first evidence for redox-linked regulation of cystathionine beta-synthase which is heme-dependent.     

Detection of genes involved in fatty acid elongation and desaturation in thraustochytrid marine eukaryotes

Heterotrophic marine protists known as thraustochytrids can synthesize polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (DHA). The biosynthetic pathways of PUFAs in thraustochytrids are poorly understood, however. In this study, we attempted to reveal the enzymes involved in DHA synthesis in thraustochytrids. Nine thraustochytrid strains representing 3 genera (Aurantiochytrium, Schizochytrium, and Thraustochytrium) were used for PCR-based detection of the genes encoding Δ5-elongase and Δ4-desaturase and for fatty acid analysis. The degenerate primers were designed to amplify the Δ5-elongase and Δ4-desaturase genes, and the partial sequences of the enzymes were obtained from the genera Thraustochytrium and Schizochytrium. These fragments were identical to those of known Δ5-elongase and Δ4-desaturase. Neither Δ5-elongase nor Δ4-desaturase was detected in the strains belonging to the genus Aurantiochytrium, however, suggesting that this group likely synthesizes DHA not via the elongation/desaturation pathway but via an alternate pathway such as the polyketide synthase pathway. The fatty acid profiles of thraustochytrids were consistent with the presence of genes involved in PUFA biosynthesis in thraustochytrid genera. Thus, our findings suggest that two biosynthetic pathways for PUFAs exist in these organisms.     

Real-time digital simulator with digital/analog conversioninterface for testing power instruments

The need for real-time simulation stems from the fact that in many practical situations it is desirable to analyze the dynamic behavior of a large power system with advanced equipment that has complex and high-speed performance. Analog simulators are effective, however they impose serious limitations on the size of the system that is being modeled. The authors have studied and developed a real-time digital simulator using a hypercube computer, and realized real-time performance available for the analysis of large power systems. As the second step of the study, they developed a digital/analog conversion interface for testing actual power instruments. The interface exchanges the variables of fundamental frequency domain in the real-time digital simulator, and the variables of exact time domain in the analog equipment connected to the simulator. In this paper, the authors describe the detail of the digital/analog conversion interface of the real-time digital simulator for testing advanced power instruments. Its conversion algorithm, system configuration of the simulator with the interface, and experimental results are also presented