Quantitative differences in the active-site hydrophobicity of five human glutathione S-transferase isoenzymes: water-soluble carcinogen-selective properties of the neoplastic GSTP1-1 species

The active-site (the H-site) hydrophobicity of five human glutathione S-transferases (GSTs) was analyzed by application of linear free energy relationships (LFERs) with a series of S-alkylated glutathione inhibitors, GS(CH2)n - 1CH3 (n = 1-14). Distinct linear reltionships were observed in the plots of log Ki (inhibition constant) vs n for the five forms, whereby the Kis varied by three to four orders of magnitude. Mean free enthalpy changes per methylene group (-Delta DeltaG degreess), a measure of H-site hydrophobicity, were in the order M1-1 (4.6 kJ/mol) > A1-1 (3. 9 kJ/mol) > A1-2 (3.8 kJ/mol) > A2-2 (2.8 kJ/mol) > P1-1 (1.6 kJ/mol). The quantitative differences may in part account for the extraordinary broad and overlapping substrate specificities of the Alpha-, Mu-, and Pi-class isoenzymes. In contrast to the Alpha and Mu classes being selective for strongly electrophilic compounds, the neoplastic P1-1 species was indicated to be selective for weakly electrophilic and water-soluble carcinogens such as acrolein and hydroxyalkenals.     

Persistence and clinical outcome of hepatitis G virus infection in pediatric bone marrow transplant recipients and children treated for hematological malignancy

The natural course and the clinical significance of hepatitis G virus (HGV) infection were investigated in 106 pediatric patients who received chemotherapy for hematological malignancy or underwent bone marrow transplantation (BMT) using HGV-RNA and antibodies to the HGV-E2 protein (anti-E2). HGV markers were detected in 21 patients (19.8%; HGV-RNA in 19 and anti-E2 in 2). Longitudinal analysis of these HGV-infected patients showed that 1 had anti-E2 before the initial blood transfusion, 14 had persistent viremia, and 6 became clear of circulating HGV-RNA after completion of therapy, although 5 of the 6 HGV-cleared patients never developed anti-E2. Reactivation of HGV infection during chemotherapy was observed in two anti-E2-positive, HGV-RNA-negative patients; the reappearance of the same HGV strain was confirmed by phylogenetic analysis. Among BMT survivors without other known causes of liver dysfunction, HGV-RNA-positive patients had a higher peak serum alanine amino transferase (ALT) value than negative patients. Contrary to previous reports, immunosuppressed patients can apparently recover from HGV infection without detectable anti-E2 and some patients who supposedly recovered from HGV infection can nonetheless suffer exacerbation when subsequently immunosuppressed.     

New monitoring approach for metabolic dynamics in microbial ecosystems using stable-isotope-labeling technologies

We have developed a new approach for monitoring the metabolic dynamics in microbial ecosystems using a combination of DNA fingerprinting and metabolome analysis based on stable-isotope-labeling technologies. Stable-isotope probing of DNA (DNA-SIP) has been used previously for the evaluation of cross-feeding in microbial communities. For the development and validation of our monitoring approach, fecal microbiota were analyzed with stable-isotope-labeled glucose used as the sole carbon source. In order to link the metabolic information and the microbial variability, we performed metabolic–microbial correlation analysis based on nuclear magnetic resonance (NMR) profiles and denaturing gradient gel electrophoresis (DGGE) fingerprints, which successfully identified the glucose-utilizing bacteria and their related extracellular metabolites. Moreover, our approach revealed information regarding the carbon flux, in that the “first” wave of extracellular metabolites secreted by the glucose-utilizing bacteria were incorporated into the “secondary” group of substrate-utilizing bacteria, and that this “secondary” group further produced their own secondary metabolized substrates. Thus, this approach is a powerful tool for monitoring the metabolic dynamics in microbial ecosystems and allows for the tracking of the carbon flux within a microbial community.     

Tofu: A 6D Mesh/Torus Interconnect for Exascale Computers

A new architecture with a six-dimensional mesh/torus topology achieves highly scalable and fault-tolerant interconnection networks for large-scale supercomputers that can exceed 10 petaflops.     

Power variation control of a wind generator by using feed forward control

The pitch control of wind generators is usually made by a feed back control concept. However, under the conditions where a wind speed changes very frequently due to geographic reasons of the site and the target system has large rotor inertia, the feed back signal which is applied to the control system to compensate disturbance such as wind speed variations is delayed, and consequently the control strategy to keep the generated power at a constant value does not work well. If the wind speed shows too much variation, this will cause a violent variation of power and result in step out operation of the generator from the power system due to magnetic saturation. This paper proposes a control strategy to reduce the power variations by introducing feed forward control combining with the conventional feed back control.     

Hand-eye system with three-dimensional vision and microgripper for handling flexible wire

A three-dimensional hand-eye system has been specially developed for handling, forming, and inserting flexible wires in electronic assemblies. The system consists of a vision system capable of measuring three-dimensional positions and a gripper capable of microforce control. The hand-eye system performs its tasks based on visual and force sensor data.The vision system uses a camera, a multiplanar laser light projector, and a video-rate image processor to measure the three-dimensional position of a flexible wire on a complex background. The projector consists of multiplanar light beams and a single-planar light beam and is robot-mountable. The single-planar light is used to simplify the matching of the multiplanar light beams and projection images. This is one of the most important features of our method. The measurement time is within 1.2 s for 20 positions on the wire, which is less than one robot cycle. The measurement accuracy is better than 0.2 mm in the plane for a 100×100 mm scene and is better than 1 mm perpendicular to the plane for a depth of 500 mm.The microgripper has 3-axis sensors capable of detecting three types of forces: grasping, pulling, and pushing. The dynamic range of the grasping force is 0.005 to 0.6 N, enabling high-resolution control. Two piezoelectric actuators are used in the microgripper fingers and a 3-mm stroke is achieved by amplifying the actuator's displacement using a two-stage lever.This system has been used for wire handling in magnetic disk slider manufacture, which is a difficult and delicate task. Measurement, grasping, and upper-stage insertion had a 100 percent success rate using autorecovery, making the hand-eye system feasible. This paper discusses design concepts, the range measurement principle, the system itself, and wire-handling applications.     

Oxygen-permselectivity in new type polyorganosiloxanes with carboxyl group on the side chain

Summary Oxygen-permselectivity through polyorganosiloxanes with carboxyl group on the side chain is discussed in terms of the differences between the O₂, N₂ diffusion coefficients or their solubility coefficients. The oxygen-selectivity increases from 2 to 5 with the increase in the carboxyl component of the side chain. Especially the selectivity in the diffusion coefficient is found to more contribute to the oxygenpermselectivity in comparison with that of the solubility coefficient. But the permeation coefficient decreases with the permselectivity.This work was partially supported by a Grand-in-Aid from the Ministry of Education, Science and Culture, Japan.     

Spark plasma sintering of ZrB<Subscript>2</Subscript>–ZrC powder mixtures synthesized by MA-SHS in air

Mechanical activation-assisted self-propagating high-temperature synthesis (MA-SHS) in air was successfully applied to the synthesis of the powder mixtures of ZrB₂ and ZrC as a precursor of the ZrB₂–ZrC composite. When the powder mixtures of Zr/B/C = 4/2/3–6/10/1 in molar ratio were mechanically activated (MA) by ball milling for 45–60 min and then exposed to air, they self-ignited spontaneously and the self-propagating high-temperature synthesis (SHS) was occurred to form ZrB₂ and ZrC. The ZrB₂–ZrC composites were produced from these MA-SHS powders by spark plasma sintering (SPS) at 1800 °C for 5–10 min and showed the fine and homogeneous microstructure composed of the <5 μm-sized grains. The mechanical properties of the composites evaluated by Vickers indentation method showed the values of Vickers hardness of 13.6–17.8 GPa and fracture toughness of 2.9–5.1 MPa·m^1/2, depending on the molar ratio of ZrB₂/ZrC. Thus, the better microstructure and mechanical properties of the ZrB₂–ZrC composites were obtained from the MA-SHS powder mixtures, compared with those obtained from the MA powder, the mixing powder and the commercial powder mixtures.     

微导通孔的电镀填孔技术

本文主介绍了电镀填孔技术,并探讨了DC和PPR电镀填孔技术的优缺点和影响填孔效果的相关因素。     

A novel FSK demodulation method using short-time DFT analysis forLEO satellite communication systems

This paper proposes a novel frequency-shift keying (FSK) demodulation method using short-time discrete Fourier transform (ST-DFT) analysis for low-Earth-orbit (LEO) satellite communication systems. The ST-DFT-based FSK demodulation method is simple and robust to a large and time-variant frequency offset because it expands the received signal in a time-frequency plane and demodulates it only by searching the instantaneous spectral peaks with no complicated carrier-recovery circuit. Two kinds of demodulation strategies are proposed: a bit-by-bit demodulation algorithm and an efficient demodulation-algorithm frequency-sequence estimation (FSE) based on the Viterbi algorithm. In addition, in order to carry out an accurate ST-DFT window synchronization, a simple DFT-based ST-DFT window-synchronization method is proposed