Biomedical subjects

W S Tong

Publications and source records attributed to W S Tong.

3 recordsLinked to original sources

PubMed2003

Limit on the electron neutrino magnetic moment from the kuo-sheng reactor neutrino experiment.

A search of neutrino magnetic moment was carried out at the Kuo-Sheng Nuclear Power Station at a distance of 28 m from the 2.9 GW reactor core. With a high purity germanium detector of mass 1.06 kg surrounded by scintillating NaI(Tl) and CsI(Tl) crystals as anti-Compton detectors, a detection threshold of 5 keV and a background level of 1 kg(-1) keV(-1) day(-1) at 12-60 keV were achieved. Based on 4712 and 1250 h of reactor ON and OFF data, respectively, the limit on the neutrino magnetic moment of mu(nu;(e))<1.3x10(-10)mu(B) at 90% confidence level was derived. An indirect bound of the nu;(e) radiative lifetime of m(3)(nu)tau(nu)>2.8x10(18) eV(3) s can be inferred.

Journal Article↗

PubMed2003

Nucleation-catalysis-kinetics analysis under dynamic conditions.

Even at large undercooling, nucleation during solidification is usually controlled by a heterogeneous process. A number of models have been devised to describe the catalytic potency of various potential nucleation sites. Most common analysis models are based upon continuum descriptions that neglect the atomistic structural features that are important at the critical nucleus size scale. Even when surface structures such as steps are considered, they are treated as static stationary features in catalysis models. At the same time, nucleation is recognized as a dynamic process. Experimental strategies to explore some aspects of nucleation dynamics have been developed based upon the droplet method. In droplet dispersions, heterogeneous catalysis can be examined in two-phase liquid-solid mixtures with well-characterized morphologies to reveal surface structure effects and catalyst dynamics.

Biophysical Phenomena↗

PubMed2001

Generating tandem repeats by cloning with double initiator fragments.

The ability to generate tandem repeats of a DNA sequence has proven important for a large variety of studies of DNA structure and function. The most commonly used method to produce tandem repeats involves cloning of an oligomerized monomer sequence that contains asymmetric overlapping ends, but, in practice, this approach is inefficient because of the circularization of oligomers before they ligate into vector. Described here is a method that circumvents this problem by the use of two separate oligomerization reactions, each containing an initiator fragment onto which monomer polymerizes without circularization. Subsequent mixing of the two reactions permits circularization, generating a viable plasmid containing the sum of the added repeats from each reaction. A variation of this method is also demonstrated that permits the synthesis of constructs with a defined number of repeats.

Cloning, Molecular↗