Simulation of water-bloom in a eutrophic lake—IV Modeling the vertical migration in a population of Microcystis aeruginosa

Simulation of the water-bloom dominated by Microcystis (blue-green algae) was carried out by modifying the mathematical model presented previously on the rising and sinking of the algal colonies through a still water-column. In contrast to the earlier work on the simulation of single colonies, an overall behavior of many algal colonies, having not only the size distribution but also having distribution initially throughout the water-column was simulated. The points of the model modified are: (i) the specific growth rate was shown by a quadratic function of light intensity that takes the inhibitory effect into account and (ii) the extinction coefficient incorporated the light-shielding effect by the algal cells existent depthwise in the water-column rather than a linear function of the concentration of suspended materials in the water.The numerical solutions of the model (280 dimensions) were in agreement qualitatively with the observations ever reported on Microcystis behavior in eutrophic lakes. Factors relevant to the extinction coefficient underwater, i.e. the concentrations of either Microcystis colonies or other suspended materials were significant from the viewpoint to control the algal growth as a whole, assuming that no nutrients were limiting. The vertical mixing of lake waters was effective for decreasing the average value of the specific growth rate expecially when the concentrations of colonies or other materials were large. Consequently, an artificial aeration was suggested to be a commendable means to ward off the water-bloom.     

硫系非晶态半导体材料的研究进展

硫系非晶态半导体材料的实验研究提示了出它具有许多新奇的光学特性实际的应用价值，本文对较新的研究成果和发展作了阐述 。     

Mechanism of the paradoxical, inhibitory effect of phenobarbital on hepatocarcinogenesis initiated in infant B6C3F1 mice with diethylnitrosamine

Phenobarbital (PB), a classical rodent hepatopromoter, remarkably enhances hepatocarcinogenesis initiated by diethylnitrosamine (DEN) in adult B6C3F1 mice. However, it is also known to strongly inhibit liver tumor development in the B6C3F1 mice initiated with DEN in their infancy. The present study aimed to elucidate the unknown biological mechanisms for this paradoxical, inhibitory effect of PB on B6C3F1 mouse hepatocarcinogenesis. Male 12-day-old infant B6C3F1 mice were injected i.p. with DEN and, at 6 weeks of age, divided into PB-treated (PB+ group) and untreated (PB- group) animals. At 24 weeks, PB treatment was ceased for half of the PB+ animals (PB+/- group) and started for half of the PB- animals (PB-/+ group). Finally, all mice were sacrificed at 36 weeks and examined for the development of liver tumors. The mean multiplicity of gross tumors in the PB+ group was only one-fifteenth of that for the PB- group. PB-/+ animals developed fewer than half of the tumors found in PB- mice, indicating that the PB effect depends solely on the treatment duration, rather than the animal age. The effect was proven to be reversible, because the mean tumor multiplicity for the PB+/- group was seven times larger than that for the PB+ group. Stereological analysis revealed the mean volume of hepatocellular proliferative lesions in the PB- animals to be 7.7- and 4.1-fold the values for the PB+ and PB-/+ groups, respectively. The mean proliferating cell nuclear antigen-labeling indices for hepatocellular adenomas in PB+ and PB-/+ animals were also one-third of that for tumors in PB- animals, whereas no significant differences were observed with regard to the mean apoptotic index. In conclusion, the inhibitory effect of PB seemed to be primarily caused by the suppression of tumor cell proliferation. Irrespective of the group, most lesions observed were basophilic hepatocellular adenomas or foci, positive for Bcl-2 oncoprotein. They were thus distinct from the eosinophilic Bcl-2- lesions that predominate with PB promotion after the initiation of adult B6C3F1 mice. This age-dependent nature of initiation, together with the differential responses of Bcl-2+ and Bcl-2- lesions, may be responsible for the apparently contradictory outcomes of PB treatment in infant and adult B6C3F1 mice.     

An Interface“Virtual Production Line”for Material Design

ＡｎＩｎｔｅｒｆａｃｅ“ＶｉｒｔｕａｌＰｒｏｄｕｃｔｉｏｎＬｉｎｅ”ｆｏｒＭａｔｅｒｉａｌＤｅｓｉｇｎ￥ＳｈｕｉｃｈｉＩｗａｔａ（ＲｅｓｅａｒｃｈｉｎｔｏＡｒｔｉｆａｃｔｓ，ＣｅｎｔｅｒｆｏｒＥｎｇｉｎｅｅｒｉｎｇ，ＴｈｅＵｎｉｖｅｒｓｉｔｙｏｆＴｏ...     

采用6个彩色LED的6基色23英寸WXGA液晶显示器

我们开发成功一种采用6个彩色LED的6基色液晶显示器,实现了具有170%色阈或者说比传统技术宽得多的6基色LCD。本研究是由日本新能源与工业技术发展机构(NEDO)组织进行的。     

Effects of C60, a Fullerene, on the Activities of Glutathione S-Transferase and Glutathione-Related Enzymes in Rodent and Human Livers

The effects of C₆₀, a fullerene, on the activities of glutathione 5-transferase (GST), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) in rodent and human livers were investigated. the GST activity in rat liver towards frans-4-phenyl-3-buten-2-one and that in mouse liver towards ethacrynic acid were inhibited by C₆₀- the GST activity towards 1,2-dichloro-4-nitrobenzene, isomerase activity of GST towards androst-5-ene-3,17-dione, GSH-Px activity and GR activity were not affected by C₆₀ a kinetic study using purified mouse GST-π with ethacrynic acid (25-100 μM) as the substrate revealed that C₆₀ was a non-competitive inhibitor of the enzyme with a K_i = 48.8 ± 0.25 μM and a K_i = 47.9 ±0.18 μM. However, C₆₀ did not inhibit the activity of purified mouse GST-π towards l-chloro-2,4-dinitrobenzene. Thus, the inhibition by C₆₀ appears to be substrate-specific. In human liver, C₆₀ inhibited the GST activity towards ethacrynic acid, and moderately inhibited GSH-Px and GR activities.     

Three yeast genes,PIR1, PIR2 and PIR3, containing internal tandem repeats,are related to each other,and PIR1 and PIR2 are required for tolerance to heat shock

We isolated three highly homologous genes, PIR1, PIR2 and PIR3, collectively called the PIR genes. The remarkable feature of their putative amino acid sequence is that they contain a sequence consisting of 18–19 amino acid residues repeated tandemly seven to ten times. Genes homologous to PIR were found in Kluyveromyces lactis and Zygosaccharomyces rouxii but not in Schizosaccharomyces pombe, suggesting that a set of PIR genes plays some role in budding yeast. Bias of codon usage seen in each of the PIR translation products suggests that they are expressed abundantly. The fact that disruption of each gene is viable indicates that none of them is essential. The double disruptants, pir1 pir2, were viable under various conditions, such as higher temperature (37°C) or high salt concentration, but showed a slow-growing phenotype on an agar slab. Furthermore, they were sensitive to heat shock. Addition of a pir3 disruption to the pir1 pir2 double disruptant brought about no phenotypic difference from the original double mutant. PIR1 and PIR3 are closely linked to each other and are on chromosome XI.     

Enhancing water flux through semipermeable polybenzimidazole membranes by adding surfactant‐treated CNTs

In this study, surfactant‐treated carbon nanotubes (CNTs) were incorporated into polybenzimidazole (PBI) matrix to prepare the PBI/CNT composite membranes with CNT content in the range of 0 to 15 wt %. The composite membranes were fabricated by spin‐coating. The membrane morphology, mechanical property, and water and salt transport properties were investigated to characterize the additive effect of CNTs. The tensile strength of all the PBI/CNT composite membranes was lower than that of pristine PBI membrane, indicating the weak interaction between CNT and PBI. In addition, water flux increased without reducing the salt rejection when CNTs were homogeneously dispersed in the PBI matrix at a less than 7.5 wt % content. On the other hand, at 10 wt % and higher CNT content, submicro‐scaled cellular structure was formed, and both the water flux and salt rejection decreased. The well‐dispersed CNTs in the PBI matrix via weak interaction preferentially improve the water permeability by 1.7 times without depressing the salt rejection. The incorporation of well‐dispersed CNTs in polymer matrix provides a promising and facile option for improvement in the water transport properties through the polymeric semipermeable membranes with intrinsically low water permeability such as PBI. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45875.     

Suppression of deicing salt corrosion of weathering steel bridges by washing

To elucidate the influences of deicing salts and high pressure (2-4 MPa) washing on the characteristics of the rust formed on weathering steel bridges, washing experiments have been carried out for three years. The rust was characterized by means of ion chromatography, X-ray diffraction and adsorption of N₂. The rust thickness was measured, and also the rust weight per unit area of the steel surface was measured. It was found that water-soluble chloride accelerated the rate of corrosion because the rust particles grow by the chloride ions and micro-pore structure of the rust appeared by the chloride ions. Washing with water suppressed corrosion owing to the disappearance of chloride ions.     

Substitution effects on the electronic anomaly and superconductivity in La2−xBaxCuO4 and La2−xSrxCuO4 with x ∼ 1/8

The effects of substitution of Y or Bi on the low-temperature structural phase transition, electronic anomaly and superconductivity have been studied in La_2-y-xY_yBa_xCuO La_2-y-xBi_yBa_xCuO₄ and La_1.9-y-xTb_0.1Bi_ySr_xCuO₄ with x = 1/8. Moreover, an electronic anomaly, which is analogous to those observed in La_2–xBa_xCuO₄ and La_1.6-xNd_0.4Sr_xCuO₄ with x 1/8, has been found below about 60 K in the thermoelectric power measurements for the Zn-substituted La_2–xSr_xCu_1–yZn_yO₄ with x 0.115 and y = 0.01 – 0.02. These experimental results support the conclusions by Tranquada et al. that static order of the stripe correlations of holes and spins, owing to pinning by the low-temperature structure or impurities (Zn in this case), is the origin of the electronic anomaly, leading to the suppression of superconductivity.