We have fabricated label-free protein biosensors based on aptamer-modified carbon nanotube field-effect transistors (CNT-FETs) for the detection of immunoglobulin E (IgE). After the covalent immobilization of 5'-amino-modified 45-mer aptamers on the CNT channels, the electrical properties of the CNT-FETs were monitored in real time. The introduction of target IgE at various concentrations caused a sharp decrease in the source-drain current, and a gradual saturation was observed at lower concentrations. The amount of the net source-drain current before and after IgE introduction on the aptamer-modified CNT-FETs increased as a function of IgE concentration. The detection limit for IgE was determined as 250 pM. We have also prepared CNT-FET biosensors using a monoclonal antibody against IgE (IgE-mAb). The electrical properties of the aptamer- and antibody-modified CNT-FETs were compared. The performance of aptamer-modified CNT-FETs provided better results than the ones obtained using IgE-mAb-modified CNT-FETs under similar conditions. Thus, we suggest that the aptamer-modified CNT-FETs are promising candidates for the development of label-free protein biosensors. 相似文献
Osteolysis caused by wear particles from polyethylene in the artificial hip joints is a serious issue. We have used photo-induced
radical graft polymerization to graft 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer onto the surface of cross-linked
polyethylene (CLPE-g-MPC) in order to reduce friction and wear at the bearing surface of the joint. The physical and mechanical properties of CLPE
and CLPE-g-MPC were not significantly different, expect that the friction coefficient of untreated CLPE cups was 0.0075, compared with
0.0009 for CLPE-g-MPC cup, an 88% reduction. After 3.0 × 106 cycles in the hip joint simulator test, we could not observe any wear of CLPE-g-MPC cups. We concluded that the advantage of photo-induced radical graft polymerization technique was that the grafted MPC
polymer gave a high lubricity only on the surface and has no effect on the bulk properties of the CLPE substrate. 相似文献
The effects of plant and yeast cerebrosides on melanin formation were examined in B16 mouse melanoma cells. Addition of yeast cerebroside significantly reduced melanin content to the same level as that of arbutin in control cells, although there was no suppression by plant cerebrosides and bovine brain cerebroside up-regulated melanin formation. None of the bovine brain cerebrosides examined had any effect on tyrosinase activity, but yeast cerebroside reduced the contents of tyrosinase. The results of the present study clearly showed that melanin formation is regulated by several different cerebrosides via tyrosinase. In addition, the findings presented here suggest that cerebrosides containing a 9-methyl type sphingoid base, such as yeast cerebroside, may be useful as skincare products for suppressing melanin formation. 相似文献
Interface properties of MBE-grown ZnSe/GaAs substrate systems formed on variously pretreated GaAs surfaces, which include
standard chemically etched (5H2SO4:1H2O2: 1H2O), (NH4)2Sx-, NH4I-, and HF-pretreated surfaces, are investigated by capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS)
measurements. A HF-pretreated and annealed ZnSe/p-GaAs sample showed marked reduction of interface state density, Nss, with Nss,min below 4 x 1011cm-2 eV-1 near Ec- EFS= 1.0 eV. The value is about one order of magnitude smaller than that of the standard chemically etched interface, and comparable
to (NH4)2Sx- pretreated interface. Nevertheless, C-V characteristics of ZnSe/nGaAs samples, which were measured for the first time, indicate
that interface Fermi level, EFS, is not completely unpinned due to the interface states located above the midgap. A consistent result was obtained by DLTS
method in determining EFS position. The influence of Nss distribution on vertical current conduction is also analyzed. It is found that U-shaped interface states with Nss(E) > 1 x 1013 cm-2 eV-1 above the midgap may cause an excess voltage drop larger than a few volts at the interface. 相似文献
The Earth Simulator (ES), developed under the Japanese government’s initiative “Earth Simulator project”, is a highly parallel vector supercomputer system. In this paper, an overview of ES, its architectural features, hardware technology and the result of performance evaluation are described.
In May 2002, the ES was acknowledged to be the most powerful computer in the world: 35.86 teraflop/s for the LINPACK HPC benchmark and 26.58 teraflop/s for an atmospheric general circulation code (AFES). Such a remarkable performance may be attributed to the following three architectural features; vector processor, shared-memory and high-bandwidth non-blocking interconnection crossbar network.
The ES consists of 640 processor nodes (PN) and an interconnection network (IN), which are housed in 320 PN cabinets and 65 IN cabinets. The ES is installed in a specially designed building, 65 m long, 50 m wide and 17 m high. In order to accomplish this advanced system, many kinds of hardware technologies have been developed, such as a high-density and high-frequency LSI, a high-frequency signal transmission, a high-density packaging, and a high-efficiency cooling and power supply system with low noise so as to reduce whole volume of the ES and total power consumption.
For highly parallel processing, a special synchronization means connecting all nodes, Global Barrier Counter (GBC), has been introduced. 相似文献
For the construction of a microwave-assisted organic synthesis plant, it is necessary to know the dielectric properties of the reaction system. Measurements of the dielectric properties of lactic acid aqueous solution, anhydrated lactic acid, oligo(lactic acid) and water, which are constituent materials in the polycondensation of lactic acid, confirm that dielectric properties decrease as reaction progresses. Calculated microwave penetration depths, obtained from the dielectric properties, show that microwaves penetrate deeply into the reaction system. This work should be useful for the development of microwave-assisted organic syntheses in the chemical industry. 相似文献
In this paper, a new assembling method of spline joints that enables tight fitting in a simple manner by allowing slight plastic deformation at the spline teeth was introduced. Experiments were carried out for the spline joints of medium carbon steel varying the overlap zone between the male and the female spline teeth. Axial joining strength was increased with increase in the overlap length due to the residual compressive stress by forming. The joint by the proposed method also showed higher torsional strength than the conventional joint. Improvement in the torsional strength was explained based on the deformation and hardness distribution around the spline teeth. With respect to the shape of overlap zone, better results were obtained when using the specimen having a uniform overlap length along the axial direction. 相似文献
Examples of developments in asymmetric hydrogenation from various perspectives, in an effort to improve efficiency, are reported. Discussed in this Account are (1) the improved synthesis of BINAP ligands, (2) the design of SEGPHOS ligands for higher enantioselectivity, (3) a new protocol with fewer reaction steps to synthesize beta-aminoesters, and (4) a novel asymmetric hydrogenation mediated by a copper catalyst. 相似文献