Effects of the SiC/Al interface reaction on fracture behavior of a composite conductor using SiC fiber reinforced aluminum for next generation power equipment

Electrical power demands are increasing every year, meaning that lightweight electric cable is needed which has high transmission capacity, high thermal resistance and low sag. Tokyo Electric Power Co., Chubu Electric Power Co. and Hitachi Cable Ltd. have been breaking new ground in the field of electric cable through the development of a SiC fiber reinforced aluminum conductor. In this work, the SiC/Al interface reaction during the manufacturing process and the electricity transmission temperature were studied by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and field emission-Auger electron spectroscopy (FE-AES) for long-term reliability assessment. No reaction products were detected at the SiC/Al interface of elemental wire consisting of 7 SiC/Al preformed wires, indicating that the wire manufacturing process was reliable. An Al₄C₃ product was detected locally at the SiC/Al interface of the wire which had been thermally treated in molten Al under unfavorable conditions. The activation energy, Q, of Al₄C₃ growth at the SiC/Al interface was about 190 kJ/mol. In the temperature range of electricity transmission, Al atoms diffused into SiC fiber during heat treatment, and the amount of the diffused Al increased with increasing treatment temperature and holding time. The activation energy of Al diffusion through the SiC/Al interface to SiC fiber was about 78 kJ/mol. Strength deterioration was not induced by Al diffusion into SiC fiber, but strength strongly depended on the formation of Al₂SiO₅ compound at the SiC/Al interface above 400°C transmission temperatures. Kinetics calculations indicated that the rate of strength deterioration of the composite cable, held at 300°C for 36 years, was about 5%, so that practical use of SiC/Al composite cable should not be far in the future.     

Rate of change of oxygen chemical potential in liquid PbO−SiO2 binary solution

The rate of the chemical potential change of oxygen in a liquid PbO?SiO₂ binary solution, with SiO₂ contents of 10, 20, and 30 mol pct, and in pure PbO, has been measured at temperatures of 900°, 950°, 1000°, 1050°, and 1100°C. The rate increased with temperature according to the Arrhenius type relation and decreased with the increase of the silica content. It is suggested that the rate-controlling step is the counter diffusion rate of Pb²⁺ and Pb⁴⁺ ions, which are considered to be the most easily movable ions in the PbO?SiO₂ solution. The relation between the rate of oxygen chemical potential change and the electrical conductivity is also discussed for the liquid PbO?SiO₂ system.     

Mechanism of Selective Phytotoxicity of l-3,4-Dihydroxyphenylalanine (l-Dopa) in Barnyardglass and Lettuce

l-3,4-Dihydroxyphenylalanine (l-dopa) is one of the few allelochemicals in which the phytotoxic action mechanism has been studied. Excess exogenous l-dopa suppresses root elongation in some plant species, and the inhibitory action is species-selective. The main factor of phytotoxicity of l-dopa is considered to be oxidative damage by reactive oxygen species (ROS) and/or free radical species (FRS). This study was performed to elucidate the mechanism of species-selective phytotoxicity. The involvement of ROS/FRS and polyphenol oxidase (PPO) in species-selective phytotoxicity was examined with barnyardgrass (Echinochloa crus-galli L.) and lettuce (Lactuca sativa L.), tolerant and susceptible species, respectively. Lipid peroxidation and melanin accumulation correlated with growth inhibition by L-dopa. Antioxidants, ascorbic acid and α-tocopherol, decreased lipid peroxidation and melanin accumulation and rescued lettuce root from growth inhibition. The oxidation of L-dopa by PPO was much greater in lettuce than in barnyardgrass. From these results, the phytotoxicity of L-dopa is considered due to the oxidative damage caused by ROS/FRS generated from the melanin synthesis pathway. PPO activity might be involved in the mechanism of species-selective phytotoxicity between barnyardgrass and lettuce.     

Mercury contamination in the Yatsushiro Sea, south-western Japan: spatial variations of mercury in sediment

Mercury-contaminated effluent was discharged into Minamata Bay from a chemical plant over a 20-year period until 1965 (from 1958 to 1959, effluent was discharged into Minamata River), causing Minamata disease. In an effort to characterize the extent of the contamination in the Yatsushiro Sea, the vertical and horizontal distributions of mercury in sediment were investigated. Sediment was sampled at 62 locations in the southern part of the sea from 4 to 6 March 1996. In the lower layers of the long cores of sediment, the total amount of mercury was at a relatively uniform low concentration. We interpret these low values to represent the background concentration absent of anthropogenic influence. The background value thus estimated for the Yatsushiro Sea was 0.059 +/- 0.013 mg kg(-1) (mean +/- S.D., n = 51). The highest concentration in each sample ranged from 0.086 to 3.46 mg kg(-1) (mean, 0.57 mg kg(-1)). The higher values were obtained at stations near Minamata Bay and the Minamata River (the sources of the pollution). Concentrations decreased with distance from the source. An inspection of the vertical profiles of mercury concentration in cores suggested that the deposited mercury had not been fixed in sediment but had been transported, despite 30 years having past since the last discharge of contaminated effluent. At nine stations, extractable inorganic and organic mercury concentrations were determined differentially. Inorganic mercury is the predominant species in sediment and organic mercury comprising approximately 1% of the total.     

High drug loading self-microemulsifying/micelle formulation: design by high-throughput formulation screening system and in vivo evaluation

Purpose: To design a high drug loading formulation of self-microemulsifying/micelle system. Methods: A poorly-soluble model drug (CH5137291), 8 hydrophilic surfactants (HS), 10 lipophilic surfactants (LS), 5 oils, and PEG400 were used. A high loading formulation was designed by a following stepwise approach using a high-throughput formulation screening (HTFS) system: (1) an oil/solvent was selected by solubility of the drug; (2) a suitable HS for highly loading was selected by the screenings of emulsion/micelle size and phase stability in binary systems (HS, oil/solvent) with increasing loading levels; (3) a LS that formed a broad SMEDDS/micelle area on a phase diagram containing the HS and oil/solvent was selected by the same screenings; (4) an optimized formulation was selected by evaluating the loading capacity of the crystalline drug. Aqueous solubility behavior and oral absorption (Beagle dog) of the optimized formulation were compared with conventional formulations (jet-milled, PEG400). Results: As an optimized formulation, d-α-tocopheryl polyoxyethylene 1000 succinic ester: PEG400?=?8:2 was selected, and achieved the target loading level (200?mg/mL). The formulation formed fine emulsion/micelle (49.1?nm), and generated and maintained a supersaturated state at a higher level compared with the conventional formulations. In the oral absorption test, the area under the plasma concentration-time curve of the optimized formulation was 16.5-fold higher than that of the jet-milled formulation. Conclusions: The high loading formulation designed by the stepwise approach using the HTFS system improved the oral absorption of the poorly-soluble model drug.     

Amorphous nanosilicas induce consumptive coagulopathy after systemic exposure

We previously reported that well-dispersed amorphous nanosilicas with particle size 70 nm (nSP70) penetrate skin and produce systemic exposure after topical application. These findings underscore the need to examine biological effects after systemic exposure to nanosilicas. The present study was designed to examine the biological effects. BALB/c mice were intravenously injected with amorphous nanosilicas of sizes 70, 100, 300, 1000 nm and then assessed for survival, blood biochemistry, and coagulation. As a result, injection of nSP70 caused fatal toxicity, liver damage, and platelet depletion, suggesting that nSP70 caused consumptive coagulopathy. Additionally, nSP70 exerts procoagulant activity in vitro associated with an increase in specific surface area, which increases as diameter reduces. In contrast, nSP70-mediated procoagulant activity was absent in factor XII-deficient plasma. Collectively, we revealed that interaction between nSP70 and intrinsic coagulation factors such as factor XII, were deeply related to nSP70-induced harmful effects. In other words, it is suggested that if interaction between nSP70 and coagulation factors can be suppressed, nSP70-induced harmful effects may be avoided. These results would provide useful information for ensuring the safety of nanomaterials (NMs) and open new frontiers in biological fields by the use of NMs.     

基于倒频谱解析法的近接型相似微地震对研究

为查明水力压裂实验所产生的人工裂隙网络区域的地应力场和局部构造特征,分析了1995～1996年在Soultz 干热岩(HDR)地热田水力压裂实验中获得的声发射数据,通过倒频谱解析法,检出近接型相似微地震对,对其进行时间-倒频率分析,结合时间-倒频率-倒频谱表示图,判断出了P波的到达时间间隔,最后标定出近接型相似微地震对的相对震源坐标,判断出人工裂隙网局部的裂隙进展方向.     

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.     

Angiotensin I-converting enzyme inhibitory activities of Chinese fermented soypaste and estimation of the inhibitory substances

Angiotensin I-converting enzyme (ACE) inhibitory activities of aqueous extracts of Chinese commercial soypaste were investigated in this work. Six samples from northern China showed potent ACE inhibitory activities with IC₅₀ values less than 40.0 μg/mL. ACE inhibitors in the sample with the strongest activity were purified by ultrafiltration, solid-phase extraction and gradient RP-HPLC. According to spectroscopic methods, a compound (M328.1) was separated as C₁₅H₂₁NO₇. It was supposed to be a conjugate of phenylalanine and glucose generated by Maillard reaction during soypaste production, providing support on the contribution of Maillard reaction products to the ACE inhibitory activity of the sample. Results further indicated that the total ACE inhibition by the sample occurred from the combined function of various bioactive substances, suggesting that Chinese soypaste could be a good source of ACE inhibitors for exploring functional foods or ingredients with antihypertensive effect.