MgSrSi-Type Compounds as a Possible New Family of Thermoelectric Materials

We calculated electronic structures and transport properties of 33 Zintl phase compounds M¹M²X (M¹, M² = Li, Na, Mg, K, Ca, Rb, Sr, Ba; X = Si, Ge, As, Se, Sn, Sb, Te, Pb, Bi) having orthorhombic MgSrSi-type (PbCl₂-type) structure. These compounds were calculated to be narrow-gap semiconductors or semimetals. By comparison with known thermoelectric materials, our analysis showed that these compounds are promising candidate new thermoelectric materials, when heavily doped with holes or electrons. The weak chemical bonds and the variety in constituent elements indicate the possibility to achieve high thermoelectric figure of merit.     

A lea-class gene of tomato confers salt and freezing tolerance when expressed in Saccharomyces cerevisiae

Although less cytotoxic, the new platinum complex [meso-1,2-bis(2,6-difluoro-4-hydroxyphenyl)-ethylenediamine]sulfatopl atinum (II) (2) is equipotent to cisplatin (1) in the oestrogen-dependent MXT mammary tumour of the mouse. As this may be due to oestrogen level-lowering properties, we compared the effect of 1 and 2 on steroidogenesis in the rat. A single dose of 1 and 2 (20 mumol/kg s.c.) decreased plasma testosterone level in male rats by 90% (1, day 3) and 80% (2, day 7). Luteinizing hormone level remained unchanged in intact and in ovariectomized rats. The activities of the following testicular enzymes were decreased (day 7): cholesterol side-chain cleavage enzyme (1: 33%; 2: 36%), 3 beta-hydroxysteroid dehydrogenase/delta 4,delta 5-isomerase (1: 31%; 2: 48%) and 17 alpha-hydroxylase/17,20-lyase (1: 21%; 2: 15%). Testicular microsomal cytochrome P450 content was also diminished (1: 60%; 2: 49%, day 7). Corticosterone level in plasma and biosynthesis in adrenal explants was not affected, indicating the selectivity of action at the gonadal level. In vitro, neither 1 nor 2 (2 and 20 microM) influenced binding of human chorionic gonadotropin to testis interstitial cells during an observation period up to 21 h. These results suggest that 1 and 2 act at the gonadal level by inhibiting the expression of the steroidogenic enzymes. They do not, however, inactivate the luteinizing hormone receptor.     

Decreased expression and functionality of NMDA receptor complexes persist in the CA1, but not in the dentate gyrus after transient cerebral ischemia

The authors investigated the gene expression of the NR2A and NR2B subunits of N-methyl-D-aspartate (NMDA) receptor and the functional electrophysiologic activity of NMDA receptor complexes in the vulnerable CA1 and less vulnerable dentate gyrus subfields of the rat hippocampus at different times after transient cerebral ischemia. Decreased expression for both subtypes was observed in both the CA1 subfield and dentate granule cell layer at early times after challenge; however, the decreased expression in the dentate granule cell layer was reversible because mRNA levels for both the NR2A and NR2B subtypes recovered to, or surpassed, sham-operated mRNA levels by 3 days postchallenge. No recovery of expression for either subtype was observed in the CA1 subfield. The functional activity of NMDA receptor complexes, as assessed by slow field excitatory postsynaptic potentiations (slow f-EPSP) in CA1 pyramidal neurons, was maintained at 6 hours postchallenge; however, this activity was diminished greatly by 24 hours postchallenge, and absent at 7 days postchallenge. A similar pattern was observed for the non-NMDA receptor-mediated fast f-EPSP. In dentate granule neurons, however, no significant change in NMDA receptor-mediated slow f-EPSP from sham control was observed at any time after insult. The non-NMDA receptor-generated fast f-EPSPs also were maintained at all times postinsult in the dentate gyrus. These results illustrate that the activity of NMDA receptors remains functional in dentate granule neurons, but not in the pyramidal neurons of the CA1 subfield, at early and intermediate times after transient cerebral ischemia, and suggest that there is a differential effect of ischemia on the glutamatergic transmission systems in these two hippocampal subfields.     

Anti-mutagenic and anti-oxidative activities found in Chinese traditional soybean fermented products furu

Furus, Chinese traditional soybean products, which are salted, fermented and seasoned bean curd preserved in dipping sauce, were studied for their anti-mutagenic and anti-oxidative activities. There are many varieties of furu by region, depending on their ingredients and bacterial strain used. Furus, not only have peculiar palatable taste and aroma, but also present strong anti-oxidative activity which ordinary Japanese soybean curd, tofu, never shows. Against benzo(α)pyrene, all samples, regardless of solid or dipping sauce, showed anti-mutagenic activity. In general, red furus had higher activity than white. All red furus inhibited more than 50% of the mutagenicity and this high suppressive ratio suggested that it was raised mainly by secreted substances discharged from the bacterial body rather than by functional compounds originating from soybeans. In the case of white furu, which showed wide differences in activity, the functional role of each spice and condiment added needs to be further studied, in addition to the soybean and white furu ferment-rice malt.     

Survey bacterial isolates from blood samples during 1987-1993 in our department

We analyzed the changes in frequency of bacterial isolates from the blood samples in our department from May 1987 to December 1993. 565 isolates from 4887 samples (11.6%) were detected. Among the detected microorganisms, the rate of gram-positivecocci (GPC) was much higher than the other kinds of the isolates each year. Especially, 80-90% of GPC were occupied by only 2 kinds of microorganisms, coagulase negative Staphylococci (CNS) and S. aureus. Among gram-negative-rods (GNR), constant increase of S. marcescens and transient increase of Enterobacter and P. aeruginosa were recognized. In 30 cases (5.3%), 2-3 kinds of microorganisms were isolated concomitantly, and in 55 cases (9.7%), the microorganisms, which was mainly caused by CNS, S. aureus and Candida, was isolated from both blood samples and the tip of the IVH catheter concomitantly. 42.5% of the bacterial positive cases in 1933 underwent 2 more kinds of the indwelling catheters and 48.3% were administrated antibiotics. Most of the cases had underlying diseases including mainly malignant tumor (leukemia, solid tumor), cerebrovascular diseases, and multiple injuries.     

Novel SOI p-channel MOSFETs with higher strain in si channel usingdouble SiGe heterostructures

We have studied p-channel advanced SOI MOSFETs using double SiGe heterostructures fabricated by the combination of SIMOX and high-quality strained-Si/SiGe regrowth technologies, in order to introduce higher strain in Si channel. It was revealed that this double SiGe structure of second Si_0.82Ge_0.18Si_0.93Ge_0.07 allows the second SiGe layer to relax by about 70%, because of the elastic energy balance between the second and the first-SiGe layers. As a result, the strain of Si layer on this double SiGe structure becomes higher than that of the single SiGe structure. Strained SOI p-MOSFETs using the double layer SiGe structure exhibited higher hole mobility than that of strained-SOI MOSFETs with single Si_0.9Ge_0.1 structure. The hole mobility enhancement of 30% and 45% was achieved in the strained-SOI MOSFETs with double SiGe structures, compared to that of the universal curve and the control-SOI MOSFETs, respectively     

Nonmetallic 1000-fiber cable

A nonmetallic high-fiber-count cable that contains fiber ribbons inserted tightly into slots and has tensile force applied to the central and slotted-rod unit strength members is described. The cable bending flexibility, tensile strain, and cable diameter, which are important for its economical and efficient construction, were theoretically and experimentally evaluated and an optimum combination of diameters for the strength members was obtained. Based on the results, a nonmetallic 1000-fiber cable was manufactured and its transmission, mechanical, and water-blocking performances were confirmed to be excellent