Fabrication of HgBa2CuO x superconductor under atmospheric pressure

We report a simple and safe technology where rather pure Hg-1201 phase superconducting bulk samples can be fabricated. The pellet was heated at about 700°C for only 30 min in open air under atmospheric pressure. We have found that a dehydration process (heating for 20 h at 250°C) is a crucial procedure for success in forming the Hg-1201 phase.     

Policy Analysis, Peer Reviewed: Toxics Release Inventories: Opportunities for Improved Presentation and Interpretation

Industrial Regulations.     

Characterization of human gamma 4 switch region polymorphisms suggests a meiotic recombinational hot spot within the Ig locus: influence of S region length on IgG4 production

Human gamma4 gene RFLPs, revealed after BamHI digestion, show IGHG4 alleles of 9.0 (9.2), 9.4, and 9.6 kb at various frequencies in different ethnic populations. Studies in immunodeficient individuals have previously suggested that the 9.4 BamHI allele is associated with a higher serum level of IgG4 than the 9.0 (9.2) BamHI allele, but it is not clear whether this is associated with the S region itself or other control elements. In addition, a duplication of the 9.4-kb gamma4 allele has recently been observed in a high proportion of normal donors. We therefore undertook a study of the structural basis for the difference in Ab levels in the various gamma4 alleles. We demonstrate that the Sgamma4 alleles differ in length due to deletions and insertions of a varying number of 79-bp Sgamma4 repeat units. Two novel RFLPs, 8.8 and 9.1 kb, were also observed. The alleles are likely to be generated by unequal crossing over, and the breakpoints cluster in Sgamma4 repeat units that contain chi-like motifs, implicating chi-like sequences in the meiotic recombination. Our data support the idea that the 9.4-kb BamHI allele is more productive than the 9.0 (9.2)-kb allele in normal healthy donors, possibly due to the extended switch regions, whereas duplication of the gamma4 gene has no effect on switching and IgG4 serum levels.     

High-efficiency Q-band GaAs FET oscillator

A microstrip GaAs FET oscillator using a 75 × 0.25 ?m device has achieved an output power of 10 mW with an efficiency of 10% at 36 GHz. This oscillator was intended for local-oscillator applications at Q-band.     

Par-4 is a mediator of neuronal degeneration associated with the pathogenesis of Alzheimer disease

Prostate apoptosis response-4 (Par-4) is a protein containing both a leucine zipper and a death domain that was isolated by differential screening for genes upregulated in prostate cancer cells undergoing apoptosis. Par-4 is expressed in the nervous system, where its function is unknown. In Alzheimer disease (AD), neurons may die by apoptosis, and amyloid beta-protein (A beta) may play a role in this. We report here that Par-4 expression is increased in vulnerable neurons in AD brain and is induced in cultured neurons undergoing apoptosis. Blockade of Par-4 expression or function prevented neuronal apoptosis induced by Ab and trophic factor withdrawal. Par-4 expression was enhanced, and mitochondrial dysfunction and apoptosis exacerbated, in cells expressing presenilin-1 mutations associated with early-onset inherited AD.     

Processing and properties of carbon nanotubes–nano-SiC ceramic

Carbon nanotubes–nano-SiC ceramic has been fabricated by the hot-press method. The preparation steps involved the use of dispersing nano-SiC powders and carbon nanotubes in butylalcohol using an ultrasonic shaker. The reasonable relative density of about 95% has been achieved by hot-pressing at 2273 K (at 25 MPa in Ar for 1 h). The three-point bending strength and fracture toughness of the composite has about 10% increment over monolithic SiC ceramic which was fabricated under the same process. The reasons for the increment are the strengthening and toughening role of carbon nanotubes occuring in the matrix.     

The use of a chimera HIV-1/HIV-2 envelope protein for immunodiagnosis of HIV infection: its expression and purification in E. coli by use of a translation initiation site within HIV-1 env gene

A chimera HIV-1/HIV-2 envelope sequence composed of multiple conserved immunodominant epitopes of HIV-1 envelope protein (HIV-1 IIIB: env482-518 + env548-675) and the HIV-2 gp36 immunodominant epitope (env592-603), was constructed and directly over-expressed in E. coli by using a prokaryotic translation initiation sequence contained within the gene of HIV-1 envelope. The recombinant product was purified and applied in antibody-screening assay. The purified chimera antigen reacted with all the thirty-eight HIV-1 positive serum samples, the two HIV-2 serum samples, and had no cross-reaction with all the eighty-eight normal healthy serum sample. The results indicated that this recombinant chimera HIV-1/HIV-2 envelope protein could be useful for diagnostic purposes of HIV infection.     

Measurement of equivalent power density and RF energy deposition inthe immediate vicinity of a 24-GHz traffic radar antenna

In response to reports of alleged health effects associated with the use of hand-held traffic radars, e.g., testicular cancer, a study was undertaken to quantify: (1) the distribution of the electric field (E) in the immediate vicinity of the antenna aperture of a typical 24-GHz hand-held traffic radar; and (2) the relative match and the corresponding depth of penetration of the absorbed energy when the antenna aperture is positioned in contact with material having properties similar to human tissue. The former measurements are important for assessing a large number of measurements reported by others using techniques that are not expected to be reliable indicators of power density at distances small compared with the size of the radiator; the latter are important for verifying predictions that energy from the antenna at 24-GHz will be predominantly absorbed in superficial tissue, i.e., the skin. The results of the first part of the study indicate that the equivalent-plane-wave power density in the plane of the aperture of the radar antenna is approximately one-half of the corresponding values reported in the literature; the results of the second part of the study indicate that the depth of penetration into material simulating human skin is approximately 0.5 mm     

A PWM method for reduction of switching loss in a full-bridgeinverter

This paper presents the “hybrid pulsewidth modulation” (HPWM) method which requires only two of the four switches in a full-bridge inverter to be pulsewidth-modulated at high frequency, thus significantly reducing the switching losses in the other two switches. For triangular carriers, HPWM has the same frequency spectrum and switching losses as the conventional unipolar PWM (UPWM). A low-frequency model for a fast-switching HPWM full-bridge inverter with high-quality output is described, and is substantiated by experimental data