Effects of trace amount of nanometric SiC additives with wire or particle shapes on the mechanical and thermal properties of alumina matrix composites

SiC nanowires (SiCNWs) are suitable candidates used as additives to improve the thermal conductivity of alumina, since they exhibit superior properties such as high chemical and thermal stability. In this study, alumina matrix composites reinforced with very small amount of β-SiC/SiO₂ core–shell nanowires were fabricated by hot-pressing. They were first characterized and compared with alumina matrix specimens containing SiC nanopowder. It was found out that with 0.2 wt% SiC additives, the grain sizes of the alumina specimens were reduced by 20 % of that of the monolithic one, regardless of the shape of the SiC additives. Vickers hardness of specimen containing both SiCNWs and SiC nanopowders slightly increased, while fracture toughness decreased more than that of the monolithic alumina. Thermal conductivity of the specimens increased with increased amount of SiCNWs and was better than those of the specimens containing SiC nanopowders. The alumina composite containing 0.2 wt% SiCNWs had higher thermal conductivity than that of the monolithic alumina by as much as 45 %. From these results, it is clear that only small amount of nanosized SiC as an additive material, particularly SiCNWs, has a significant effect on the properties of alumina matrix composites.     

Adaptively controlled supercontinuum pulse from a microstructure fiber for two-photon excited fluorescence microscopy

Selective fluorescence excitation of specific molecular species is demonstrated by using coherent control of two-photon excitation with supercontinuum pulses generated with a microstructure fiber. Pulse shaping prior to pulse propagation through the fiber is controlled by a self-learning optimization loop so that the highest fluorescence signal contrast between two fluorescent proteins is obtainable. The self-learning optimization loop successfully controls both the optical nonlinarity of the microstructure fiber and the two-photon excitation of the fluorescent proteins.     

Lymphatic Absorption and Deposition of Various Plant Sterols in Stroke-Prone Spontaneously Hypertensive Rats,a Strain Having a Mutation in ATP binding cassette transporter G5

ATP binding cassette transporter G5 (ABCG5) and ATP binding cassette transporter G8 (ABCG8) have been suggested to transport absorbed plant sterols and cholesterol from enterocytes to the intestinal lumen and from hepatocytes to bile. It has been thought that mutations of ABCG5 or ABCG8 cause the deposition of plant sterols in the body. In the present study, lymphatic absorption of various plant sterols and their deposition in various tissues was investigated in stroke-prone spontaneously hypertensive rats (SHRSP), having a mutation in Abcg5 and depositing plant sterols in the body. The order of lymphatic 24-h recovery of plant sterols was as follows: campesterol > sitosterol > brassicasterol > stigmasterol = sitostanol. When SHRSP were fed a diet containing one of the plant sterols, the depositions of campesterol and sitosterol were comparatively higher than those of brassicasterol, stigmasterol and sitostanol. Highly positive correlations were obtained between lymphatic recovery of plant sterols and their levels in plasma, liver, adipose tissue and heart. The tendency of differential absorption of plant sterols to the lymph in SHRSP was similar to that in normal Wistar rats previously reported by us (Hamada et al. Lipids 41:551–556, 2006). These observations suggest that differential absorption of various plant sterols is kept in SHRSP in spite of a mutation in Abcg5.     

Application of grass char for Cd(II) treatment in column leaching test

Various adsorbents as well as toxicants have been investigated regarding the adsorption behaviors and mechanisms. However, most of these reports were based on batch test. The discrepancy in adsorption behaviors between batch test and column test has been recognized recently. This study was to investigate the sorption behavior of Cd(II) in a novel adsorbent made from Reed char. Batch adsorption test and column leaching test were both conducted. Various influence factors including confining pressure, pH, velocity, concentration and ionic strength were studied. The velocity was found to have negligible effect on the breakthrough of Cd(II). The adsorption affinity was observed for the first time to decrease from a high value (R(d) = 130.00) to a negligible one (R(d) = 1.20) with increasing confining pressure from 0 to 100.00 kPa. The breakthrough of acid Cd(II) solution was earlier for solutions with less pH and higher ionic strength. The Cd(II) laden adsorbent was reclaimed by flushing chelants through the column. The recycled adsorbent appeared to be applicable in the following adsorption treatment. Suggestions were provided regarding the potential engineering applications.     

Planning of occupational dose reduction at BWR power plant by past dose record analysis combined with on-site workers' idea analysis

In order to establish a plan for occupational dose reduction at operating plants, outage inspection works that involve high-dose exposure were selected and a determination of the major causes of high-dose exposure made by plant-by-plant comparison of doses received during inspection works. The comparison was made to investigate the relationship between exposure and the volume of objects to be inspected, working time and man-hour of each work process and ambient dose rates at work areas. In parallel with this, an analysis has also been carried out on 400 data items in a questionnaire survey conducted on relevant individuals, including foremen, radiation safety personnel, on-site workers and plant designers regarding ideas for dose reduction methods. With combination of these two analyses, matters that require improvement will be highlighted, then modification of equipment or revision of work procedures necessary for occupational dose reduction will be planned by plant designers through review.     

The relation between activated carbon adsorption and water quality indexes

In order to estimate the adsorbability by activated carbon of organic compounds dissolved in aqueous solutions, the contribution of individual atoms to the adsorption process is calculated. The contribution of carbon, bromine and chlorine atoms is positive, that of oxygen atoms is negative, that of hydrogen atoms is very small and that of nitrogen atoms is influenced by the kind of functional group in which they are contained. The dominant factors governing adsorption are the numbers of carbon and oxygen atoms in a molecule. The activated carbon's effectiveness for adsorption of organic compounds dissolved in solutions can be predicted from such water quality indexes as total organic carbon, total organic nitrogen, total organic halogen an total oxygen demand.     

Seamless signal transduction from live cells to an NO sensor via a cell-adhesive sensing matrix

A smart live-cell assay was developed as a cellular biosensing system. This system is based on novel tactics: the direct assembly of human cultured cells onto a cell-adhesive sensing matrix. This novel design provides considerable advantages, among them the possibility of capturing molecular signals immediately after they are secreted from living cells. The design also helps preserve all cellular characteristics intact. In this study, a cell-adhesive NO sensing matrix, acting as both an NO-permeable membrane and a cell-adhesive scaffold, was designed using functional polymers and a short peptide sequence derived from extracellular matrix (ECM) proteins. Using the cell-adhesive NO sensing matrix, we constructed a cellular biosensing system based on in situ monitoring of NO released from a human umbilical vein endothelial cell (HUVEC) layer. HUVECs were employed as an organ-functional model of a blood vessel in view of screening vasodilatory substances for clinical purposes. In our novel system, the electrochemical NO sensor is adjacent to the NO-producing cells, which allows the sensing device to achieve superior sensitivity and precise response to a very low number of NO molecules. Our design enables the fixing of the exact distance between the organ-functional model and the chemical sensor without cumbersome manipulations. Consequently, this cellular biosensing system may be readily applicable to high-throughput analysis in the field of drug screening.     

Gingival and dermal fibroblasts: their similarities and differences revealed from gene expression

Gene expression profiles in normal human gingival and dermal fibroblasts were investigated using DNA microarrays. Their fundamental characteristics were almost identical, but 5% of their genes were uniquely expressed. These results help us to choose an optimal cell source for effective fibroblast-based cell therapy that is dependent on differential gene expression profiles.     

Intelligent speed-increasing spindle using traction drive

An intelligent speed-increasing spindle using a wedge-roller-traction drive (WTD) is developed to realize high-accuracy milling. The WTD is a type of planetary roller variator, whose ring and sun rollers are nonconcentric. The generation of little heat is a feature of the WTD. Some cutting tests were carried out, and the measured surface roughness of the WTD spindle was found to be better than that of a commercially available speed-increasing spindle using planetary gears. Moreover, the function of measuring cutting torque during end milling was added to make the spindle intelligent. The countertorque at the carrier is measured using a piezofilm. Measurement and calibration procedures were proposed and their effectiveness was confirmed by experiments.