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SY Wang

Publications and source records attributed to SY Wang.

12 recordsLinked to original sources
PubMed1999

Inhibition of Crystallite Growth in the Sol-Gel Synthesis of Nanocrystalline Metal Oxides.

Crystal growth upon firing of hydrous transition metal oxide gels can be effectively inhibited by replacing the surface hydroxyl group before firing with another functional group that does not condense and that can produce small, secondary-phase particles that restrict advancing of grain boundaries at elevated temperatures. Accordingly, fully crystallized SnO(2), TiO(2), and ZrO(2) materials with mean crystallite sizes of approximately 20, 50, and 15 angstroms, respectively, were synthesized by replacing the hydroxyl group with methyl siloxyl before firing at 500 degrees C. An ultrasensitive SnO(2)-based chemical sensor resulting from the microstructural miniaturization was demonstrated.

Journal Article↗
PubMed1999

Probability distribution of the four-phase structure invariants of isomorphously related structure factors and its applications.

The probability distribution of the four-phase structure invariants (4PSIs) involving four pairs of structure factors is derived by integrating the direct methods with isomorphous replacement (IR). A simple expression of the reliability parameter for 16 types of invariant is given in the case of a native protein and a heavy-atom derivative. Test calculations on a protein and its heavy-atom derivative using experimental diffraction data show that the reliability for 4PSI estimates is comparable with that for the three-phase structure invariants (3PSIs), and that a large-modulus invariants method can be used to improve the accuracy.

Journal Article↗
PubMed1999

Methyl Jasmonate Reduces Water Stress in Strawberry.

The effect of methyl jasmonate (MJ) on changes of oxygen-scavenging enzyme activities and membrane lipid composition was studied in strawberry leaves under water stress. Under water stress, MJ treatment reduced the increase of peroxidase (EC 1.11.1.7; POD) activity, maintained higher catalase (EC 1.11.1.6; CAT) and superoxide dismutase (EC 1.15.1.1; SOD) activities, and ascorbic acid content. In addition, MJ treatment reduced transpiration and membrane-lipid peroxidation as expressed by malondialdehyde (MDA) content, lessened the reduction of membrane lipids, glycolipids [monogalactosyl diglyceride (MGDG), digalactosyl diglyceride (DGDG)], and phospholipids [phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylinositol (PI)]. In water-deficit conditions, MJ treatment also alleviated the decline in the degree of fatty acid unsaturation and the ratio of linolenic (18:3) to linoleic acid (18:2). These results indicate that MJ treatment appears to alter the metabolism of strawberry plants rendering the tissue better able to withstand water stress.

Journal Article↗
PubMed1996

Establishment and Persistence of Baculovirus penaei Infections in Cultured Pacific White Shrimp, Penaeus vannamei

The time course for establishment of a baculovirus (BP) infection and the persistence of infections in larvae and postlarvae of the Pacific white shrimp, Penaeus vannamei was investigated. In two preliminary studies, postlarvae were inoculated with BP and the prevalence of infections was monitored over 138- and 73-day periods. Viral polyhedra characteristic of patent infections first appeared 24 hr after inoculation, were present in all shrimp examined 14-17 days postinoculation (p.i.), and then decreased in prevalence during the remainder of each study. BP infections could not be detected by in situ hybridization in shrimp collected during the final day of each study. In a third and more comprehensive study, PCR-based diagnostic procedures were used to detect BP in experimentally infected shrimp over a 120-day period. In that study, BP was first detected in viral exposed mysis stage shrimp 12 hr p.i., was present in all shrimp examined by 72 hr p.i., and decreased in prevalence during the remainder of the study. BP infections could not be detected by PCR-based diagnostics in shrimp collected on the final day of the study. Only 1 of 10 previously infected shrimp collected at 31 days p.i. and diagnosed for BP by bioassay was infected. Results of this study indicate similarities between P. vannamei and some species of insects in the time required for establishment and loss of a patent baculovirus infection.

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