Search

Deals with a study that described undoped indium phosphide epilayers grown directly on (100) silicon substrates by low-pressure organometallic vapor-phase epitaxy. Factors that improve with indium phosphide thickness; Indication of x-ray and photoluminescence measurements for indium phosphide heteroepilayers; Approaches employed to improve the properties of indium phosphide on silicon.

Examines heteroepitaxial growth of indium phosphide on gallium arsenide by low-pressure metalorganic chemical vapor deposition. Application of Auger depth profiles; Evident effect of growth temperature on electron mobility; Overview of the surface morphology of the epilayers using scanning electron microscopy.

Heteroepitaxial growth of InP on ZnSe-coated Si substrates by low-pressure metalorganic vapor phase epitaxy is reported for the first time. Single-crystal InP epilayers with specular surfaces can be obtained. The ZnSe buffer layer, which is evaporated onto the Si substrate in another furnace, is effective in reducing the magnitude of strain in the InP layer. The best room-temperature electron mobility of the undoped InP epilayer can reach 3100 cm2 /(V s) with a carrier concentration of 1.5×1015 cm-3 . It was found that the InP electron mobility is critically dependent on the ZnSe buffer-layer thickness. The efficient photoluminescence compared with that of InP homoepitaxy indicates that the InP heteroepilayer is of high optical quality. [ABSTRACT FROM AUTHOR]

Heteroepitaxial growth of InP on Si with an intermediate GaAs buffer layer by low-pressure organometallic vapor phase epitaxy is reported. Excellent crystallinity of InP epilayers with specular surfaces can be reproducibly obtained. The carrier concentration profile shows that the carrier distribution in the InP layer is very uniform, while an apparent reduction in concentration occurs at the InP/GaAs interface. The 77 K photoluminescence (PL) of the InP layer exhibits a strong near-band-edge emission. No evident shift in PL peak energy for the InP/GaAs/Si sample compared with that for the InP homoepitaxial sample was first observed in this study. These results are superior to those reported previously for the InP/Si heteroepitaxy. [ABSTRACT FROM AUTHOR]

Metalorganic vapor phase epitaxy of InP prepared by a trimethylindium-trimethylphosphine (TMIn-TMP) adduct and PH3 was first grown in a low pressure vertical reactor. The adduct with its irreplaceable merit of high stability has been successfully used in this study. The lowest carrier concentration of undoped InP epilayers is 5×1014 cm-3 with a 77 K mobility of 75 000 cm2/V s. The full width at half-maximum of the 77 K photoluminescence spectrum was as narrow as 10 meV. These results can compete with all previous data from adduct sources. The growth rate was not limited by the relatively low vapor pressure of the TMIn-TMP adduct and could reach to 8 μm/h. It suggests the high growth efficiency of this growing process. [ABSTRACT FROM AUTHOR]

Hyperthermic preconditioning attenuates the heat-induced cellular response to a subsequent severe heat challenge. However, it is impractical to perform whole-body hyperthermia in humans. This study was designed to test the hypotheses that hepatic heat shock protein 70 (Hsp70) could be induced by local somatothermal stimulation (LSTS) on right seventh intercostal nerve territory and that preconditioning the rats with LSTS protects the liver from subsequent ischemia-reperfusion injury. LSTS was brought about by application of a heating rod above right seventh intercostal nerve territory in male Sprague-Dawley rats. Hepatic gene expression of Hsp70 was assessed by Western blot and reverse transcription polymerase chain reaction (RT-PCR). Finally, serum ALT and AST and the lipid peroxidation product malondialdehyde (MDA) were evaluated in ischemic-reperfused rats preconditioned by application of LSTS on right seventh intercostal nerve territory. The results showed that hepatic gene expression of Hsp70 was upregulated in rats treated with LSTS. When animals were preconditioned with LSTS, followed by subsequent ischemia-reperfusion injury of the liver, there were significant decreases in liver enzymes (ALT/AST) and MDA formation in rats pretreated with one dose of LSTS (LSTS-1 group) as compared with those not treated with LSTS (control group) or treated with three doses of LSTS (LSTS-3 group). We conclude that mild local heat stress (one dose) on right seventh intercostal nerve territory upregulates hepatic gene expression of Hsp70 and protects the liver from subsequent ischemia-reperfusion injury. This might provide an easily applicable method for those patients facing ischemia-reperfusion challenge of the liver, as in liver resection and liver transplantation., (Copyright 2001 Academic Press.)

This work is a study of the freeze crystallization process developed for the production of a rapidly soluble and stable crystalline form of imipenem, an antibiotic. The objective is to understand the relationship between process conditions and the product crystallinity during the freeze crystallization. Solutions of imipenem and sodium bicarbonate, a drug stabilizer, were crystallized in acetone-water solvent systems at various ratios and temperatures. The degree of crystallinity of the resulting products was measured using an X-ray powder diffraction analysis technique. The acetone-water S-L phase diagram was used to correlate the resulting degrees of crystallinity of imipenem products and equilibrium properties of the system. It was discovered that the conversion of amorphous imipenem to crystalline products was directly related to the percentage of equilibrium liquid during the freeze crystallization. Solubility data indicated that imipenem is virtually insoluble in these equilibrium liquid phases. This suggests that the phase transition from the amorphous state to the crystalline state is mediated by the presence of the liquid phase.

A cross-section study was carried out to assess the general patterns in use of antimicrobial agents and the trends of bacterial resistance in Huashan Hospital. Of 2,400 patients whose charts were reviewed, 61% were given such drugs. 3,596 antibiotic courses were prescribed. Gentamicin was most frequently used. Results of the susceptibility test of 320 bacterial strains showed a high percentage of resistance against gentamicin, ampicillin, and chloramphenicol. Our findings suggest that antibiotic policies in the hospital need reappraising.