Capacitance-voltage characteristics of Semiconductor-Insulator-Semiconductor (SIS) structure

The ideal low- and high-frequency capacitance-voltage curves of a semiconductor(2)-insulator-semiconductor(1) (SIS) structure were first calculated with the insulator thickness, conductivity types and doping concentrations in semiconductor(1) and semiconductor(2) as parameters. The effects of fixed oxide charge and interface trap charge on the low and high frequency capacitance-voltage curves were also calculated. It was found that the fixed oxide sheet charge density with its centroid and the order estimation of the interface trap charge density with its effective type in addition to the insulator thickness, conductivity types and doping concentrations in semiconductor(1) and semiconductor(2) could be estimated from measured low and high frequency capacitance-voltage curves of an SIS structure.     

InP/InGaAsP p-type substrate and mass transported doubly buried heterostructure laser

A novel InP/InGaAsP buried heterostructure laser diode on p-type InP substrate has been developed. The laser has achieved a threshold current as low as 20 mA DC with high power output of 50 mW under CW operation in the fundamental transverse mode.     

柿叶多酚的提取及体外生物活性的研究

利用水以及不同体积百分比(20%、40%、60%、80%和100%)的甲醇、乙醇、丙酮时柿(Diospyros kaki cv.Mopan)叶中的多酚物质进行提取,提取率最高的不同溶剂提取物采用HP-20大孔树脂进行纯化,分别得到了水提取物(WE)、甲醇提取物(ME)、乙醇提取物(EE)和丙酮提取物(AE),并时不同提取物的体外抗氧化活性、胶原酶和酪氨酸酶抑制活性进行了分析和比较.结果表明.柿叶中的多酚含量相于27.4±0.21mg GA/g(干重).采用体积分数为60%的丙酮溶液提取柿叶多酚时.柿叶多酚的提取率最高,为74.3%±2.3%.60%丙酮提取物对1,1-二苯基-2-苦基苯肼(DPPH)自由基的清除能力最高,达O.27±0.02μmol Trolox/mg,对胶原酶和酪氨酸酶也具有较高的抑制活性,IC50值分别为92.8 4-2.9μg/mL和185.4±5.3μg/mL.     

Identification of Aloe species by random amplified polymorphic DNA (RAPD) analysis

Juice and integument of leaves of 3 Aloe species, Aloe vera, A. ferox and A. africana, are not allowed to be used as food according to the Pharmaceutical Affairs Law in Japan. On the other hand, whole leaves of A. arborescens can be used as food. The present study was designed to distinguish Aloe species by random amplified polymorphic DNA (RAPD) analysis. DNA was isolated from fresh and dried leaves of the 4 Aloe species. Five out of 32 different 10-mer primers examined were useful for analysis. By comparison of the characteristic bands of PCR products on agarose gel, it was possible to distinguish the 4 species. Thus, the botanical species of Aloe in commercial food products can be identified by RAPD analysis.     

Effect of subarachnoid haemorrhage on micro-circulation in hypothalamus and brain stem of dogs

In order to investigate the relationship between cerebral vasospasm and microvasculature in the hypothalamus and brain stem, colloidal carbon was infused into the vertebral artery at various time intervals after experimental subarachnoid haemorrhage in dogs. Experiments which demonstrated vasospasm on angiogram were always accompanied by ischaemic changes in serial sections taken from the anterior hypothalamus to the brain stem. However, when it was demonstrated by angiography that the vasospasm had disappeared, the micro-circulation was restored to normal. Electron microscopy of the hypothalamus 48 hours and one week after subarachnoid haemorrhage, demonstrated swelling of the endothelial cells, enlargement of the perivascular glia and increase in number of the pinocytic vesicles in the cytoplasm, thus showing vasogenic oedema in this area. It is assumed that in addition to the vasogenic substance in extravasated blood, changes in irritability of cerebral vessels through the vasomotor pathways in the hypothalamus and brain stem might play an important role in the production of cerebral vasospasm.     

Investigation of pathways of advanced glycation end-products accumulation in macrophages

Advanced glycation end-products (AGE) play a role in the pathogenesis of several diseases, including diabetic complications and atherosclerosis. In atherosclerotic lesions of human aortas, AGE are localized in the extracellular matrix and intracellularly in foam cells. Two interpretations are possible for AGE accumulation inside macrophages, one is endocytic uptake of extracellular AGE-proteins by scavenger receptors; the other is intracellular AGE formation inside the macrophages. In the present study, we determined the pathways involved in AGE accumulation inside macrophages. RAW 264.7 cells, a murine macrophage cell line, incubated with BSA and 1600 mM glucose for 40 weeks, recognized heavily modified AGE- BSA. In contrast, the cells showed no ligand activity for mildly modified AGE-BSA, prepared by incubating BSA with 50 mM glucose for 24 weeks. Nepsilon-(carboxymethyl)lysine (CML)-modified proteins of about 65 kDa were detected in human monocyte-derived macrophages incubated for 7 days with 30 mM glucose and phorbol myristate acetate. Furthermore, CML was generated when glycated protein was incubated with hypochloric acid. Taken together, our results indicate that AGE detected inside foam cells in atherosclerotic lesions are generated intracellularly rather than representing endocytic uptake of extracellular AGE-proteins by scavenger receptors.     

Augmentation of polysialic acid by valproic acid in early postnatal mouse hippocampus and primary cultured hippocampal neurons

We examined the effects of valproic acid (VPA) on hippocampal neurons. Prenatal VPA exposure significantly increased polysialic acid (PSA) expression in the early postnatal mouse hippocampus. Moreover, VPA treatment significantly enhanced PSA expression in primary cultured hippocampal neurons and stimulated neurite growth. Our results suggest that VPA exposure in ovo affects hippocampal development.     

Construction of Cellulose Binding Domain Fusion FMN-Dependent NADH-Azoreductase and Glucose 1-Dehydrogenase for the Development of Flow Injection Analysis with Fusion Enzymes Immobilized on Cellulose

The cellulose binding domain (CBD) of cellulosome-integrating protein A from Clostridium thermocellum NBRC 103400 was genetically fused to FMN-dependent NADH-azoreductase (AZR) and glucose 1-dehydrogenase (GDH) from Bacillus subtilis. The fusion enzymes, AZR-CBD and CBD-GDH, were expressed in Escherichia coli Rosetta-gami B (DE3). The enzymes were purified from cell-free extracts, and the specific activity of AZR-CBD was 15.1 U/mg and that of CBD-GDH was 22.6 U/mg. AZR-CBD and CBD-GDH bound strongly to 0.5 % swollen cellulose at approximately 95 and 98 % of the initial protein amounts, respectively. After immobilization onto the swollen cellulose, AZR-CBD and CBD-GDH retained their catalytic activity. Both enzymes bound weakly to 0.5 % microcrystalline cellulose, but the addition of a high concentration of microcrystalline cellulose (10 %) improved the binding rate of both enzymes. A reactor for flow injection analysis was filled with microcrystalline cellulose-immobilized AZR-CBD and CBD-GDH. This flow injection analysis system was successfully applied for the determination of glucose, and a linear calibration curve was observed in the range of approximately 0.16–2.5 mM glucose, with a correlation coefficient, r, of 0.998.