Effect of reduced pressure on oxidation and thermal stability of polycarbosilane-derived SiC fibers

To clarify the effects of reduced pressure on the thermal stability of polycarbosilane-derived SiC fibers (Nicalon, Hi-Nicalon and Hi-Nicalon S), the heat-treatments were conducted at 1623 and 1723 K under total pressures (p _T) of 1–10⁵ Pa. The oxidation behavior and thermal stability of the fibers were investigated through examinations of mass change, grain growth, specific resistivity, fiber morphology and tensile strength. All the fibers were definitely oxidized in the active-oxidation regime at p _T 10² Pa and T = 1723 K. Nicalon and Hi-Nicalon S were subjected to serious degradation of fiber strength. Hi-Nicalon had a strength of 1.2 GPa even after heat-treatment at p _T = 1 Pa.     

Fiber-optic sensor using an injection-locked local laser

An interferometric fiber-optic sensor using a local laser is proposed. An Er-doped-fiber ring-laser is injection locked to a signal carrier using a fiber coupler, and the extracted carrier is directly homodyned with the signal light at the output of the coupler. With a feedback loop suppressing the local laser instability, demodulation linearity over two decades and minimum detection in the 10^-3 rad range are attained. The Er-doped fiber ring laser constructed for this work has a linewidth of less than 1.4 kHz. Acceptable signal frequency ranges and the linearity and sensitivity of the proposed sensor are examined. Also discussed is the applicability of this configuration to simple, long-spanned sensors     

Electrooptic leaky anisotropic waveguides using nematic liquid crystal overlays

This paper describes the experimental results on two types of electrooptically controllable leaky anisotropic waveguides using nematic liquid crystal (LC) overlayers. In these constructions the conversion of a guiding structure into a leaky one or a reverse operation is feasible by applying an electric field. They showed a switching of millisecond order with an extinction ratio of 20 dB at 30-V peak-to-peak (p-p) applied.     

Serum eosinophil cationic protein in infants during first wheezing episode

We measured serum ECP levels in infants during first wheezing episode. Serum ECP in these infants are significantly higher than in control infants, although much higher in children with asthma. Serum ECP in these infants with high serum IgE and/or positive RAST score are higher than in infants with normal serum IgE and negative RAST score. In children with bronchial asthma serum ECP is correlated with peripheral eosinophil counts, but in infants during first wheezing episode serum ECP is often elevated not associated with increased peripheral eosinophil counts. These suggest that activated eosinophils could be responsible for bronchoconstriction in wheezing patients with atopic diathesis even in very early phase and that these eosinophilic inflammations could contribute to formation of increased airway reactivity and bronchial asthma.     

Increased incidence of cytomegalovirus (CMV) infection and CMV-associated disease after allogeneic bone marrow transplantation from unrelated donors. The Fukuoka Bone Marrow Transplantation Group

The purpose of this study was to identify correlates of physical activity behavior in a sample of rural, predominantly African American youth. Three hundred sixty-one fifth-grade students from two rural counties in South Carolina (69% African American, median age = 11 years) completed a questionnaire designed to measure beliefs and social influences regarding physical activity, physical activity self-efficacy, perceived physical activity habits of family members and friends, and access to exercise and fitness equipment at home. After school physical activity and television watching were assessed using the Previous Day Physical Activity Recall (PDPAR). Students were classified as physically active according to a moderate physical activity standard: two or more 30-min blocks at an intensity of 3 METs (metabolic equivalents) or greater, and a vigorous physical activity standard: one or more 30-min blocks at an intensity of 6 METs or greater. According to the moderate physical activity standard, 34.9% of students were classified as low-active. Multivariate analysis revealed age, gender, television watching, and exercise equipment at home to be significant correlates of low activity status. According to the vigorous physical activity standard, 32.1% of the students were classified as low-active. Multivariate analysis revealed age, gender, television watching, and self-efficacy with respect to seeking support for physical activity to be significant correlates of low activity status. In summary, gender and the amount of television watching were found to be the most important correlates of physical activity in rural, predominantly African American youth.     

Depressant effects of volatile anesthetics on second messenger system in mRNA-expressed Xenopus laevis oocytes

In this study I attempted to elucidate the depressant effects of volatile anesthetics on inositol trisphosphate (IP3)-mediated signal transduction pathway and to identify the site of action. For this purpose, we used Xenopus laevis oocytes which translated and expressed 5-HT receptors after injection of mRNA isolated from the rat brain. In this system, binding of the agonist to G-protein coupled receptors activates phospholipase C that produces IP3. Mobilization of Ca2+ by IP3 from the storage finally opens Ca2+ dependent Cl- channels. Halothane, isoflurane and methoxyflurane depressed Cl- current elicited by 5-HT. For the further quantitative study, methoxyflurane was used because of its better solubility and less vapor pressure that avoided evaporation of the agent. The 5-HT elicited Cl- current was depressed in a non-competitive fashion. Response were 75, 60, 20% of control in the presence of 0.5, 1 and 3 mM methoxyflurane, respectively. Responses elicited by a pressure-injection of Ca2+ or IP3 remained unchanged in the presence of high concentrations of either halothane, isoflurane or methoxyflurane. These results suggest that the depressant mechanism by volatile anesthetics on the signal transduction pathway involves neither Ca2+ dependent Cl- channel dynamics nor intracellular Ca2+ mobilization by IP3. Changes of microdomain characteristics of the membrane in the presence of anesthetic molecules including membrane-bound proteins and enzyme system may be a main mechanism of action of volatile anesthetics.     

Yeast sequencing reports. Molecular cloning and sequencing of the hcs gene,which encodes 3-hydroxy-3-methylglutaryl coenzyme a synthase of Schizosaccharomyces pombe

We have cloned and sequenced the hcs gene, which is thought to encode a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase consisting of 447 amino acids, from the fission yeast Schizosaccharomyces pombe. The predicted amino acid sequence of the hcs product of S. pombe has homology with the HMG-CoA synthase of rat (47·8%), chicken (49·2%), hamster (47·1%) and human cells (46·9%). One of the hcs genes was replaced with a marker gene in the diploid cell. No viable hcs-disrupted haploid was isolated after tetrad dissection, suggesting that the hcs gene is essential for growth. However the hcs-defective mutant could be grown on a medium containing 5 mg/ml mevalonate. These results strongly support that the hcs gene encodes HMG-CoA synthase and S. pombe contains a single copy of the hcs gene. The sequence of the hcs gene has been entered into the public data libraries under Accession Number U32187.     

Systematization in the Central Clinical Laboratory of Kyoto University Hospital

Recently, computer systems including several delivery systems have been installed in the Central Clinical Laboratory of Kyoto University Hospital. As for the physiological examination system, we have introduced PRINS (Physiological-examination Result Information Network System) using an NEC computer and LAN. Utilizing Windows, this PRINS is connected to individual systems and equipment, and the data are sent to the host computer system (KING: Kyoto University Hospital Information Network Galaxy, which utilizes IBM). This system enabled us to greatly improve (1) the efficacy of examinations, (2) management and data-stock of huge volumes, (3) rapid data analyses and simplicity in handling, and (4) facility of reception and reservation business. As for the sample analysis system, we formerly developed computer systems using MUMPS independently in the subdivisions. At the time of delivery system installation, we decided to unify them and newly establish a general managing system using MUMPS Sumitomo Electric Industries. The purpose of these installations are briefly as follows; (1) to reduce human power and to simplify delivery of samples and related business, (2) to report the assay results rapidly, (3) to improve and automate the quality controls, (4) to prevent from infections, and (5) to make handling and work easier. This system is comprised of biochemistry, immunology, hematology and emergency examination subdivisions, and connects each part in a network system using LAN. This is further connected to KING, the host. Actually, 4 sample delivery lines from 3 industries were introduced: Hitachi for biochemistry, Sysmex for hematology, and Toshiba-IDS for coagulation and immunology. Monitoring and data analyses including quality controls are performed by a host system or individual systems (biochemistry and hematology). At present, such heterogeneous installations were considered to be most suitable for our purpose and these made it possible to continue assays of other lines even when trouble occurred in one of the lines. In addition to the general systems, we have introduced various software programs for statistical analyses. These have been effectively utilized already for detailed setting of the clinical reference values for hematology data, and also for a computer diagnosis trial for anemia related diseases. When effective operations of these newly installed systems is achieved, we would like to extend our efforts to establish an ideal laboratory which is able to assist the intensive medi-care system in the university hospital.     

Radiation-induced solid-state polymerization in binary systems. V. Polymerization in binary systems containing long chain compounds

Radiation-induced solid-state polymerization in binary systems containing long-chain compounds has been investigated. Butyl stearate–methyl methacrylate and stearyl alcohol–methyl methacrylate systems have been studied in detail. In these systems insource polymerization does not occur but a remarkable post-polymerization takes place on warming after irradiation at low temperature. The limiting conversion characteristics of this post-polymerization depend greatly on the nature and the concentration of the long-chain compounds. The post-polymerization is observed to be more marked in the butyl stearate–methyl methacrylate system than in the stearyl alcohol–methyl methacrylate system, and it increases with increasing concentration of the long-chain component. An optimum warming rate and warming temperature exists for the maximum saturated conversion. Irradiation in air causes some decrease of conversion compared to irradiation in vacuo. The possible mechanism is that monomer diffuses into the crystals of the long-chain compound after melting at the eutectic temperature. The polymerization may be initiated by trapped radicals of the long-chain compound and carried out in the crystal of the long-chain compound with a smaller possibility of termination. In binary systems containing long-chain compounds, lowering of the melting point is slight, and the eutectic composition exists at the richer composition of monomer, so almost all the long-chain substance remains as excess crystals, which are suitable for holding trapped radicals. The crystal lattices of long-chain compounds may be softer than those of compounds of small molecular size. This fact is favorable for monomer diffusion. This explains why such a post-polymerization takes place only in systems containing long-chain molecules.     

Preparation and sintering of narrow-sized Al2O3-TiO2 composite powders

Narrow size distribution Al₂O₃-TiO₂ composite powders containing nominally 10 to 60 mol % TiO₂ were prepared by the stepwise hydrolysis of titanium alkoxide in an Al₂O₃ dispersion. Particle size was controlled by selecting the particle size of the starting Al₂O₃ powder. The TiO₂ content was determined by the amount of alkoxide hydrolysed. Composite powder compacts were prepared by filter casting or centrifugal casting the composite powder dispersions. All compacts had similar shrinkage behaviour during sintering. When fired above 1300° C, the compacts containing less than 50 mol % TiO₂ became Al₂TiO₅-Al₂O₃ composite bodies with high densities, the compact containing 50 mol % TiO₂ became an Al₂TiO₅ body with domain structure, and the compact containing 60 mol % TiO₂ formed a TiO₂-Al₂TiO₅ composite structure. When these composite bodies were annealed below 1300° C, they showed different decomposition behaviour and microstructures.