A 1.45-W/mm, 30-GHz InP-channel power HEMT

The authors report the fabrication of the first AlInAs/InP power HEMT with a saturated power density of 1.45 W/mm, a maximum power-added efficiency of 24%, and a large signal gain of 6.2 dB at 30 GHz. The authors show that the estimated power performance of this device at the highest frequencies is better than for any three-terminal devices because the f_t of the power HEMT is high, even at high drain-source bias     

Composition and properties of whey protein concentrates from ultrafiltration

Chemical and nutrient composition and functional properties of whey protein concentrates from ultrafiltration of sweet and acid wheys were studied for potential food uses. Vitamins passed readily through the membrane; thus, vitamin content was slightly higher than in whey. Amino acid values were considerably higher, increasing in direct proportion to increases in protein. Lysine availability was not significantly affected by fractionation or by subsequent beat treatment. Since this process results in substantial removal of minerals along with the permeate, the protein to ash ratio of the protein concentrate increased. Unlike most other methods of recovering protein from whey, solubility was not adversely affected by ultrafiltration. However, protein concentrates were susceptible to heat; normal pasteurization temperatures resulted in approximately 20% denaturation. Whey protein exhibited excellent water retention. Addition of 1.5% protein to skim milk followed by heating formed a custard-like gel with sufficient body to stand alone without leakage. Approximately twice as much egg albumin was required to achieve comparable results. Whipping properties were very good when butterfat content was less than 2%. Excellent stable whips could be produced by a combination of heat and pH adjustment.     

Estradiol-mimetic probes. Preparation of 17 alpha-(6-aminohexynyl)estradiol biotin, fluorescein and acridinium conjugates

3-O-tert-Butyldimethylsilyl-17 alpha-(6-mesyloxyhexynyl)estradiol was converted to the azide in 60-70% yield with NaN3/DMPU, then reduced to the corresponding amine (> 95% yield). Acylation with the N-hydroxysuccinimide esters of biotin, 5-carboxyfluorescein and 10-(3-sulfopropyl)-N-tosyl-N-(3- carboxypropyl)acridinium-9-carboxamide gave the title conjugates. The KDs of the tracers with an estradiol antibody ranged from 97-197 nM.     

O-(fluoresceinylmethyl)hydroxylamine (OFMHA): a fluorescent reagent for detection of damaged nucleic acids

5- and 6-O-(Fluoresceinylmethyl)hydroxylamine (OFMHA, 5a, b) were prepared from the corresponding bis-pivaloyl-protected hydroxymethylfluoresceins (1a, b) in 50-70% yield. The hydroxylamine derivatives reacted smoothly with the abasic sites present in acid/heat stressed calf thymus DNA.     

Novel AlInAs/InP HEMT

The fabrication of the first AlInAs/InP HEMT is reported. This device has extrinsic transconductance of 40 mS/mm, gate-drain and drain-source breakdown voltages of 20 V and saturation drain current densities of 0.1 A/mm of gate width. These preliminary results show the potential of the AlInAs/InP heterojunctions for a wide variety of application including microwave power HEMTs.<>