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Biomedical subjects

M Z Yang

Publications and source records attributed to M Z Yang.

9 recordsLinked to original sources
PubMed2006

In situ study of mass transfer in aqueous solutions under high pressures via Raman spectroscopy: a new method for the determination of diffusion coefficients of methane in water near hydrate formation conditions.

A new method was developed for in situ study of the diffusive transfer of methane in aqueous solution under high pressures near hydrate formation conditions within an optical capillary cell. Time-dependent Raman spectra of the solution at several different spots along the one-dimensional diffusion path were collected and thus the varying composition profile of the solution was monitored. Diffusion coefficients were estimated by the least squares method based on the variations in methane concentration data in space and time in the cell. The measured diffusion coefficients of methane in water at the liquid (L)-vapor (V) stable region and L-V metastable region are close to previously reported values determined at lower pressure and similar temperature. This in situ monitoring method was demonstrated to be suitable for the study of mass transfer in aqueous solution under high pressure and at various temperature conditions and will be applied to the study of nucleation and dissolution kinetics of methane hydrate in a hydrate-water system where the interaction of methane and water would be more complicated than that presented here for the L-V metastable condition.

Algorithms↗
PubMed1997

[Studies on sultamicillin hydrolysis].

Sultamicillin is an oral mutual pro-drug composed of double esters of formaldehyde hydrate in which one of the hydroxyl groups is esterified with ampicillin and the other with sulbactam. It is hydrolyzed fast in neutral or weakly alkaline condition. When hydrolyzed, it forms ampicillin and hydroxylmethyl sulbactam or sulbactam and hydroxylmethyl ampicillin by different routes. Usually, the former has priority as the two ester bonds have different activities. The ratio of ampicillin to sulbactam in the products is about 3:1. Both the hydroxylmethyl sulbactam and the hydroxylmethyl ampicillin can be further catalyzed by esterase to produce formaldehyde.

Ampicillin↗
PubMed1989

[Retention index of essential oil in temperature-programmed capillary column gas chromatography].

Kovats retention indexes of more than 200 kinds of natural and synthetic compounds of alcohol, aldehyde, acetal, ketone, ether, alkene, nitrile, carboxylic acid, ester, etc. were determined on polar liquid phase (DB-WAX) and nonpolar liquid phase (DB-1) by linear temperature-program capillary column gas chromatography. Some rules of part of the homologous series of compounds were summed up from the retention indexes: the rules of RI vs carbon, RI vs boiling point and RI on two columns. In order to keep the retention indexes practical, effects of initial temperature (T0), program rate (r) and average linear carrier gas velocity (u), etc. on the retention indexes were investigated. The conclusion is that the retention indexes are highly reproducible so long as the program parameters change in a certain range. Two kinds of essences, Meigui and Linglan, were identified successfully on IBM-PC/XT microcomputer by the Data Base Management System of essential oil and essence by capillary column gas chromatography and the results are satisfactory.

Chromatography, Gas↗
PubMed1989

Reaction of Se with SH groups in spectrin is involved in the stabilization of erythrocyte membrane skeleton.

Na2SeO3 supplementation in the dialysis medium could obviously prevent the dissociation of spectrin from the erythrocyte membranes. Such Se effect could be eliminated by pretreatment of erythrocyte membranes with a SH-blocking reagent, iodoacetamide(IAA) or addition of a SH-compound, dithio-threitol. The fluorescence intensity of erythrocyte membranes labelled with the fluorescent probe N-(3-pyrenyl)-maleimide decreased with increasing Na2SeO3 concentration used for pretreatment of ghosts. 31P-NMR spectra of erythrocyte membrane dialyzed in the presence or absence of Na2SeO3 concentration showed a difference in chemical shift anisotropy (delta sigma) between these two samples. These data suggest that the stabilization effect is based on changes in lipid-protein interaction and conformation of membrane skeletal components induced by reaction of their SH groups with Na2SeO3.

Chemical Phenomena↗
PubMed1989

Effects of gossypol on Na+, K+ transmembrane fluxes in human red cells.

The effects of gossypol-acetic acid (a male contraceptive) on transmembrane fluxes of sodium and potassium in human red cells were studied, in comparison with the effects of ouabain (an inhibitor of Na+-K+-ATPase) and furosemide (an inhibitor of Na+, K+ cotransport). It was found that gossypol may be an inhibitor of outward (Na+, K+) cotransport in human red cells but has no significant effect on (Na+, K+)-ATPase. The results provide new evidence for elucidating the mechanism of hypokalemia caused by gossypol.

Erythrocyte Membrane↗
PubMedDate not supplied

Survey of public awareness, understanding, and attitudes toward epilepsy in Henan province, China.

The awareness, understanding, and attitudes toward epilepsy in 1,278 men and women were surveyed in Henan, China in 1988. Results showed that 93% had read or heard about epilepsy; 77% knew someone who had epilepsy; 72% had seen someone who was having a seizure; 57% would object to having their children associate with persons with epilepsy in school or at play; 87% would object to having their children marry a person with epilepsy; 53% believed that epileptic persons should not be employed in jobs as other persons are; 16% believed that epilepsy was a form of insanity; 40% did not know the cause of epilepsy; 10% did not know what an epileptic attack was like; and 17% did not know what to recommend if their friends or relatives had epilepsy. The relationship between the responses and the respondents' age, sex, marital status, number of offspring, level of education, occupation, and residence was analyzed. Education reduced the respondent's prejudice against play and employment, but did not change their objection to marriage and appeared to have reinforced their linking epilepsy with insanity. As compared with the surveys conducted in Western countries, our survey showed that awareness of epilepsy in China was greater, if not the same, but the attitudes toward epilepsy were much more negative.

Adolescent↗