Biomedical subjects
Publications and source records attributed to Z S Yang.
We describe a reflection scheme that allows Bragg-spaced semiconductor quantum wells to be used to trap, store, and release light. We study the temporal and spectral distortion of delayed light pulses and show that this geometry allows multibit delays and offers a high degree of distortion compensation.
We report the experimental observation of coherently coupled heavy-hole-light-hole Stark shifts, i.e., light-hole exciton shifts under heavy-hole exciton pumping conditions, in InGaAs quantum wells. The theoretical analysis of the data is based on a full many-body approach (dynamics-controlled truncation formalism) in the third-order nonlinear optical regime. It is shown that the Stark shift data can be interpreted as strong evidence of suitably defined nonradiative intervalence band coherences in a semiconductor quantum well. Hence, the observations establish a semiconductor analog of Raman coherences in three-level atoms.
A strain of Enteroinvasive Escherichia coli was isolated from the stool with blood and mucus of a child suffering from acute diarrhea. The strain shows the following characteristics: rapid fermentation of glucose (with gas), no fermentation of lactose, beta-galactosidase reaction positive, growth in acetate media, lysine decarboxylase negative, non-motility causing keratoconjunctivitis in guinea pigs and invading into epithelial cells, with a plasmid of 140 Md, Serotype is O121:H- which is a new serotype of Enteroinvasive Escherichia coli.
The strains of EIEC serotype O28ac:K73 (B):H-were isolated from two episodes of food poisoning in Beijing during July to September in 1984. All strains were examined by E. coli K12 and found that they possessed the ability to produce the same colicin and same phage sensitivity pattern to eight phages isolated from contaminated water in Beijing area. These characteristics were different from reserved strains O28ac and other strains of E. coli. It indicated that two episodes were caused by the same phage type of O28ac:K73 (B):H-and proved the local outbreak was caused by same strain in western area of Beijing. The authors discussed in detail. The differentiation methods for plaque formation produced by colicin and phage.
A new alkaloid, phlegmariuine-N, was isolated from Phlegmariurus fordii (Baker) Ching. In the present work, a technique of long-range 1H-1H and 13C-1H COSY in combination with NOE difference spectroscopy has been successfully used to connect the spin systems separated by quatermary carbons and heteroatom. Its structure has been elucidated as (I).
results of identification and serotyping of enteroinvasive escherichia in china from 13 provinces in China in 1984-85 were reproted.
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Hybridoma-derived monoclonal antibodies were prepared against outer membrane antigens of four strains of Vibrio cholerae that were cultivated under iron-limited conditions, and these antibodies were partially characterized. We established a library of 66 hybridomas which produced monoclonal antibodies defining 16 different V. cholerae antigens. Two antigens (molecular weights, 18,000 and 112,000) were heat modifiable, whereas the reacting epitope of a third antigen (40,000-dalton-18,000-dalton doublet) was completely destroyed when it was heated at 100 degrees C. The 112,000-dalton heat-modifiable protein was an iron-regulated outer membrane protein. This protein bound 59Fe in vitro when it was combined with the V. cholerae siderophore-iron complex 59Fe-vibriobactin; it was also found in in vivo grown V. cholerae, as were three other antigens. A total of 26 hybridomas produced antibody to V. cholerae lipopolysaccharide. Of these, 12 were cross-reactive with lipopolysaccharides of other gram-negative bacteria, including 2 which recognized lipid A. Several of these anti-lipopolysaccharide monoclonal antibodies appeared to be lipopolysaccharide region specific. Some membrane antigens were strain specific, whereas others were common to both O group 1 and non-O group 1 vibrios.
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A latex particle agglutination test previously shown to be suitable for the rapid identification of Escherichia coli strains of human origin producing heat-labile enterotoxin (R. A. Finkelstein and Z. Yang, J. Clin. Microbiol. 18:23-28) is equally applicable to strains of porcine origin.