A study and optoelectronic verification of AlGaAs/GaAsheterojunction bipolar transistor large-signal characteristics

A hybrid optoelectronic measurement system is constructed and used to obtain the large-signal characteristics of AlGaAs/GaAs heterojunction bipolar transistors. The measurement system utilizes a terahertz-bandwidth electrooptic transducer gated by 100-fs laser pulses to interrogate the time-domain waveforms at the device input and output nodes. A microwave signal phase-locked to the laser pulse-train is used to synchronously excite the device in both small-signal and large-signal regimes. The measurement system is capable of 50-GHz bandwidth and provides time-domain voltage waveforms that can be used directly to verify the time-domain results of the large-signal analysis     

A corrosion study of nickel–copper and nickel–copper–palladium welding filler metals

In an effort to reduce the release of fumes containing carcinogenic Cr⁶⁺ during arc welding of stainless steel, Cr‐free filler metals for welding of SS304 have been developed. Corrosion studies were carried out on 304L stainless steel samples welded with these Cr‐free consumables. The corrosion properties of gas tungsten arc (GTA) and shielded metal arc (SMA) welds fabricated with Ni? Cu and Ni? Cu? Pd consumables were found to be comparable to those of welds fabricated with SS308L, the standard filler metal used with SS304. Although the breakdown potentials of the welds made using both welding processes were lower than that of the SS308L GTA weld, the repassivation potentials of these welds were much higher. Generally, the repassivation potential is a more conservative measure of susceptibility to localized corrosion. Accordingly, the Ni? Cu and Ni? Cu? Pd welds were more resistant to crevice corrosion than SS308L welds. The addition of a small amount of Pd improved the corrosion resistance relative to Ni? Cu welds, which is consistent with previous studies from specially‐prepared button samples and bead‐on‐plate samples. Other corrosion studies such as creviced and uncreviced long time immersion, atmospheric exposure, and slow strain rate testing suggest that Ni? Cu? Pd filler metal can be a potential replacement for the conventional SS308L filler metal for joining SS304.     

Variations in personal space as a function of authoritarianism, self-esteem, and racial characteristics of a stimulus situation.

Investigated "personal space," the portable, flexible area surrounding an individual which has been viewed as a buffer zone between him and his environment. It was hypothesized that when 20 high and 20 low self-esteem and authoritarian white male undergraduates were approached by white and black male stimuli, (a) the largest areas of personal space would be used by high authoritarian, and low self-esteem ss; and (b) these ss would also use larger areas of personal space in response to the approach of the black stimulus than the white. The hypotheses are supported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthetic Peptides Related to Horse Heart Cytochrome C II. Peptides Corresponding to Positions 50–56

Synthesis is described of a series of peptide derivatives which corresponds to positions 50–56 in the primary structure of horse heart Cytochrome C. The preparation of the protected heptapeptide: t-butyl t-butyloxycarbonyl-β-benzyl-L-aspartyl-L-analyl-L-asparaginyl-?-trifluoroacetyl-L-lysyl-L-asparaginyl-?-trifluoroacetyl-L-lysylglycinate is described.     

Hydroxyaliphatic acids in branched copolymers with acyl chloride-terminated long side chains: A new shrink-resist treatment for wool

Two synthetic routes were followed to prepare graft copolymers with long side chains containing acyl chloride terminal groups. In the first of these methods acryloxy aliphatic acyl chlorides were synthesized from ricinoleic acid, 12-hydroxystearic acid and 10-hydroxydecanoic acid and then polymerized with other acrylate ester comonomers. In the second procedure, a prepolymer was formed by copolymerizing acryloyl chloride with acrylate esters. The prepolymer then was treated with 12-hydroxystearic acid or 9(10)-hydroxymethylstearic acid to produce polymers with side chains having terminal carboxylic acid groups. These polymers were made more reactive by conversion to acid chlorides. The active polymers were applied to wool fabrics; the imparted shrink-resistance was durable under an accelerated wash test procedure. An added advantage of the treatment is a soft “hand” or feel resulting from internal plasticization of the polymer coating. No. Market. Nutr. Res. Div., ARS, USDA. W. Market, Nutr. Res. Div. ARS, USDA.