Adsorption of bovine serum albumin to a polymer brush prepared by atom-transfer radical polymerization in a porous inorganic membrane

Protein adsorption was performed by a polymer brush prepared by atom-transfer radical polymerization (ATRP) to a porous inorganic membrane. The porous inorganic membrane, Shirasu Porous Glass made from silica, was modified with a halogen-containing compound to bind the active species for the polymerization. Glycidyl methacrylate was polymerized from the halogen compound by ATRP for a prescribed time, and subsequently chemically modified. The progression of the chemical modification allowed the membrane to lower the phosphate-buffer flux of the porous membrane due to the attachment of the polymer brush. Bovine serum albumin (BSA), as a model protein, was adsorbed at 12 mg per gram of the membrane in permeating BSA solution through the polymer-brush-attached porous membrane.     

纳米SiO_2制备方法研究

以溶胶—凝胶法(sol-gel)为基础,乙醇作溶剂,在氨水催化作用下,研究了正硅酸乙酯(TEOS)通过水解聚合反应制备Si O2微球的方法,并探讨n(水)/n(TEOS)(简称H)及反应时间等因素的影响。本实验借助激光散射粒度分布分析仪研究Si O2微球在溶液态的分布情况,同时使用SEM对烘烤干燥后的Si O2微球进行表征,该方法制得的纳米Si O2微球分布集中,平均粒径在90 nm左右。     

Present or Past Herbivory: A Screening of Volatiles Released from <Emphasis Type="Italic">Brassica rapa</Emphasis> Under Caterpillar Attacks as Attractants for the Solitary Parasitoid, <Emphasis Type="Italic">Cotesia vestalis</Emphasis>

Females of the solitary endoparasitoid Cotesia vestalis respond to a blend of volatile organic compounds (VOCs) released from plants infested with larvae of their host, the diamondback moth (Plutella xylostella), which is an important pest insect of cruciferous plants. We investigated the flight response of female parasitoids to the cruciferous plant Brassica rapa, using two-choice tests under laboratory conditions. The parasitoids were more attracted to plants that had been infested for at least 6 hr by the host larvae compared to intact plants, but they did not distinguish between plants infested for only 3 hr and intact plants. Although parasitoids preferred plants 1 and 2 days after herbivory (formerly infested plants) over intact plants they also preferred plants that had been infested for 24 hr over formerly infested plants. This suggests that parasitoids can distinguish between the VOC profiles of currently and formerly infested plants. We screened for differences in VOC emissions among the treatments and found that levels of benzyl cyanide and dimethyl trisulfide significantly decreased after removal of the host larvae, whereas terpenoids and their related compounds continued to be released at high levels. Benzyl cyanide and dimethyl trisulfide attracted parasitoids in a dose-dependent manner, whereas the other compounds were not attractive. These results suggest that nitrile and sulfide compounds temporarily released from plants under attack by host larvae are potentially more effective attractants for this parasitoid than other VOCs that are continuously released by host-damaged plants.     

Microstructures of Annealed TiNiSn-Based Alloy Ribbons

The thermoelectric half-Heusler compounds Ti _x NiSn_0.998Sb_0.002 (x = 1.0 to 1.2) and Ti _y Zr_0.25Hf_0.25NiSn_0.998Sb_0.002 (y = 0.5 to 0.65) with nonstoichiometric nominal compositions were prepared by spin-casting and subsequent annealing at 1073 K for 24 h. The dimensionless figure of merit ZT at room temperature was maximized at x = 1.1 and y = 0.6 in Ti-rich compounds through an increase in absolute Seebeck coefficients despite a decrease in electrical conductivities. ZT reached 0.07 at x = 1.1 and 0.14 at y = 0.6. In powder x-ray diffraction analysis, minor phases of β-Sn, TiNi, Ti₂Sn, and Ti₅Sn₃ were observed in addition to a major phase of half-Heusler. The quantity of the minor phases was minimized at x = 1.1 and y = 0.55, where the absolute Seebeck coefficients are maximized. In transmission electron microscopic (TEM) analysis of Ti_0.55Zr_0.25Hf_0.25NiSn_0.998Sb_0.002, crystal grains of the half-Heusler phase, from several hundred nanometers to several micrometers in size, were observed. TEM energy-dispersive spectroscopy measurements indicated that fluctuations of Ti, Zr, and Hf compositions within the Ti-site in the half-Heusler phase may occur. Thermoelectric properties were improved at x = 1.1 and y = 0.6 rather than at the stoichiometric compositions of x = 1.0 and y = 0.5 due to minimization of the precipitate quantities.     

Effect of BN nanoparticle content in SiC matrix on microstructure and mechanical properties of SiC/SiC composites

BN-nanoparticle-containing SiC-matrix-based composites comprising SiC fibers and lacking a fiber/matrix interface (SiC/BN + SiC composites) were fabricated by spark plasma sintering (SPS) at 1800°C for 10 min under 50 MPa in Ar. The content of added BN nanoparticles was varied from 0 to 50 vol.%. The mechanical properties of the SiC/BN + SiC composites were investigated thoroughly. The SiC/BN + SiC composites with a BN nanoparticle content of 50 vol.%, which had a bulk density of 2.73 g/cm³ and an open porosity of 5.8%, exhibited quasiductile fracture behavior, as indicated by a short nonlinear region and significantly shorter fiber pullouts owing to the relatively high modulus. The composites also exhibited high strength as well as bending, proportional limit stress, and ultimate tensile strength values of 496 ± 13, 251 ± 30, and 301 MPa ± 56 MPa, respectively, under ambient conditions. The SiC fibers with contents of BN nanoparticles above 30 vol.% were not severely damaged during SPS and adhered to the matrix to form a relatively weak fiber/matrix interface.     

Preparation of smooth and dense composite films consisting of MEHPPV and neat C60 by means of electrophoretic deposition

A procedure to prepare flat and dense composite films of a conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] (MEHPPV) and various amounts of neat C₆₀ by means of electrophoretic deposition from dilute suspensions is reported. It has been observed that deposition from suspensions containing both components results in pinhole-free films, which are applicable to photovoltaic devices, while inhomogeneous films are formed from the suspensions containing only one of the components. The applicability of electrophoretic deposition to obtain polymer-C₆₀ composite films showing photovoltaic effects has been successfully demonstrated.     

International mobility of researchers in robotics,computer vision and electron devices: A quantitative and comparative analysis

We investigated author information in scientific articles by approximately 7,000 researchers for a quantitative analysis of researchers’ international mobility. From top journals, we traced the movements of more than 2,200 researchers in the research domains of robotics, computer vision and electron devices. We categorized countries’ characteristics for the balance between the inflow and the outflow of researchers moving internationally. Flow patterns of international mobility confirm that the United States, China and India exhibit the greatest global flows of researchers, with Singapore and Hong Kong attracting remarkable numbers of researchers from other countries. International mobility focusing on institutions reveals that universities in Singapore receive as many foreign researchers as do research universities in the United States. Furthermore, firms and international collaborative research institutes act as alternative receivers to the universities in the electron devices research domain.     

Biocompatibility of a-C:H film coating for synthetic vascular graft

Amorphous hydrogenated carbon (a-C:H) films have many excellent properties such as biocompatibility, anti-corrosion, and chemical stability. Therefore, there are many reports on application of a-C:H film as surface modification technique for biomaterials. However, it is difficult to deposit a-C:H film on complex structures such as artificial heart blood pump and synthetic vascular grafts. In our previous work, we have developed an electrode which is adapted to such irregular structures for plasma CVD technique.In this study, a-C:H film was deposited on a synthetic vascular graft inner-wall by r.f. plasma CVD technique with cylindrical electrode. The purpose of such coating is improvement of biocompatibility of the vascular graft. The biocompatibility of the a-C:H film was evaluated by cytocompatibility and plasma protein adhesion. For the a-C:H film deposition, cytocompatibility and protein adsorbent of the vascular grafts were improved for biological response under cell culture with mouth fibroblasts and plasma proteins (albumin, fibrinogen, and globulin), respectively. This study indicates that the a-C:H films coatings is expected to surface modification for medical appliances.