Hierarchical polymer nanocomposite coating material for 316L SS implants: Surface and electrochemical aspects of PPy/f-CNTs coatings

Biocompatible nanocomposite coatings can be synthesized to offer improved surface properties for biomaterials and biomedical implants. Nanocomposite coatings containing polypyrrole (PPy) matrix reinforced with functionalized multi-wall carbon nanotubes (f-CNTs) were deposited on 316L SS substrates using electrochemical route. FT-IR, XRD, SEM, and TEM were employed to characterize the nanocomposite microstructure. High resolution imaging showed relatively uniform dispersion of the CNTs in the nanocomposite with a typical tubular structure. Micro-indentation tests revealed improvement in the hardness of the PPy/CNTs coatings. Measurement of the contact angle indicated enhanced surface wettability of the nanocomposite coatings. The corrosion behavior of 316L SS samples coated with PPy/CNTs was studied in SBF medium. The corrosion potential and the breakdown potential of coated 316L SS substrates shifted to more noble values as compared to uncoated 316L SS samples. The results suggest that incorporating CNTs as reinforcements in PPy coatings can provide enhanced properties in terms of surface hardness, biocompatibility, and corrosion resistance.     

An immuno-wall microdevice exhibits rapid and sensitive detection of IDH1-R132H mutation specific to grade II and III gliomas

World Health Organization grade II and III gliomas most frequently occur in the central nervous system (CNS) in adults. Gliomas are not circumscribed; tumor edges are irregular and consist of tumor cells, normal brain tissue, and hyperplastic reactive glial cells. Therefore, the tumors are not fully resectable, resulting in recurrence, malignant progression, and eventual death. Approximately 69–80% of grade II and III gliomas harbor mutations in the isocitrate dehydrogenase 1 gene (IDH1), of which 83–90% are found to be the IDH1-R132H mutation. Detection of the IDH1-R132H mutation should help in the differential diagnosis of grade II and III gliomas from other types of CNS tumors and help determine the boundary between the tumor and normal brain tissue. In this study, we established a highly sensitive antibody-based device, referred to as the immuno-wall, to detect the IDH1-R132H mutation in gliomas. The immuno-wall causes an immunoreaction in microchannels fabricated using a photo-polymerizing polymer. This microdevice enables the analysis of the IDH1 status with a small sample within 15 min with substantially high sensitivity. Our results suggested that 10% content of the IDH1-R132H mutation in a sample of 0.33 μl volume, with 500 ng protein, or from 500 cells is theoretically sufficient for the analysis. The immuno-wall device will enable the rapid and highly sensitive detection of the IDH1-R132H mutation in routine clinical practice.     

Kinetics of CO2 reforming of methane by catalytically activated metallic foam absorber for solar receiver-reactors

Ni–Cr–Al metallic foam absorber with high porosity was catalytically activated using a Ru/γ-Al₂O₃ catalyst, and was subsequently tested with respect to CO₂ reforming of methane in a small-scale volumetric receiver-reactor by using a sun-simulator. A chemical storage efficiency of 37% was obtained for a mean light flux of 325 kW m⁻². Furthermore, the activity and the stability of the metallic foam absorber were compared with those of a SiC foam absorber activated with the same Ru/γ-Al₂O₃ catalyst for 50 h of light irradiation, and it was found that the metallic foam absorber has superior catalytic stability in comparison to the SiC form absorber. In addition, unlike ceramic foams such as SiC, metallic foams feature superior plasticity, which prevents the emergence of cracks caused by mechanical or thermal shock.     

Determination of dissolved natural thorium and uranium in Horonobe and Mizunami Underground Research Laboratory groundwater and its thermodynamic analysis

At two underground research laboratories situated at Horonobe and Mizunami, Japan, trace amounts of natural thorium and uranium dissolved in deep groundwater were investigated with the help of chemical pre-concentration method. The groundwater was sampled from underground boreholes under the geochemical condition of no atmospheric exposure, and the colloid contribution was checked by in situ two size-fractionated ultrafiltration systems. A rough decrease by half in the concentration after in situ filtration suggested the presence of natural colloids and suspended matter that were carriers of a portion of the elements. The Th and U concentrations in groundwater after 10 kDa filtration was evaluated as dissolved species, and was identified thermodynamically using existing hydrogeological and geochemical data, such as the mineral components in the groundwater at a given pH, ionic strength, concentration of co-existing ions, redox potential, and a hypothetical solubility-limiting solid phase. The crystalline solid phase of tetravalent thorium and uranium dioxides made the solubility very low compared with that of the amorphous phase.     

A novel spherical carbon

We developed a novel spherical carbon material. The spherical carbon is composed of a high density of carbon nanotubes or nanofilaments, and includes an oxidized diamond particle as a core. Syntheses of this carbon in high volume with high selectivity may be possible. It is expected that this carbon will be useful as a catalyst material for fuel cells, electric double-layer capacitors, etc.     

Preparation of Fe-based monodisperse spherical particles with fully glassy phase

In this study, we prepared monodisperse spherical particles of a desired diameter using [(Fe_0.5Co_0.5)_0.75B_0.2Si_0.05]₉₆Nb₄ alloy; the particles were prepared by using an atomization process developed by us. The particles have perfect sphericity and narrow size distribution along with a homogeneous composition. The phase transitions of particles from the fully glassy phase to the crystalline phase via mixed phase structures occurred as the particle diameter was increased; the particles produced in the fully glassy phase in an argon atmosphere had a diameter of less than 300 μm. This allowed the estimation of the intrinsic critical cooling rate for the particles with a fully glassy phase, R_c:R_c varied in the range of 700-900 K/s and depended only on the initial temperature of the alloy melt.     

Electric transfer function model of switched reluctance motors and model‐based current control design

This paper presents a current control design for switched reluctance motors (SRMs). The electric transfer characteristic of the motors is studied first. Their transfer function is shown to be expressible by a pure resistive component, which is not constant but varies depending on the motor current and speed. The current control design for SRMs follows the classical design technique used for DC machines, where the zeros of the PI controller cancel the poles of Ls+R. Because the transfer function of SRMs does not have any poles, an I controller is suitable for them. The integral gain should be adjusted in order to compensate the nonlinearity, that is, the variation in the equivalent resistor of the SRMs' transfer function. The values of the integral gain are tuned and tabulated for the motor speed and current. Simulation and experiment demonstrate that the current and speed of the SRMs present good responses without dependence on the motor speed and current. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(1): 51–59, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20987     

Criteria for versatile GaN MOVPE tool:high growth rate GaN by atmospheric pressure growth

Growth rate has a direct impact on the productivity of nitride LED production.Atmospheric pressure growth of GaN with a growth rate as high as 10μm/h and also Al_0.1Ga_0.9N growth of 1μm/h by using 4 inch by 11 production scale MOVPE are described.XRD of（002） and（102） direction was 200 arcsec and 250 arcsec, respectively.Impact of the growth rate on productivity is discussed.