Biomedical subjects

Xiaoyi Gong

Publications and source records attributed to Xiaoyi Gong.

3 recordsLinked to original sources

PubMed2006

Multiparallel chiral method development screening using an 8-channel microfluidic HPLC system.

The Eksigent Express 800 8-channel microfluidic HPLC system was investigated for carrying out multiparallel screening and development of fast normal phase chiral separations. In contrast to the familiar automated sequential chiral method development approaches that often afford a next day result, the multiparallel approach offers the exciting possibility of near "real time" method development, often affording an optimized method in less than 1 h. In this study, four column types (300 microm i.d.) with two different mobile phases are screened using a universal standard gradient approach. Interestingly, parallel method optimization following initial screening was shown to sometimes lead to surprising and unanticipated outcomes, emphasizing the value of the multiparallel screening approach. A variety of standard test racemates were analyzed, with optimized separation methods for most in the 1- to 2-min range. These results compare favorably with results obtained on a single channel conventional HPLC system using 4.6-mm i.d. columns. In addition, isocratic methods developed on the microbore columns are readily translated to the larger column format.

Benzoin↗

PubMed2005

Synthesis of 1-tert-butyl-4-chloropiperidine: generation of an N-tert-butyl group by the reaction of a dimethyliminium salt with methylmagnesium chloride.

Two efficient routes to 1-tert-butyl-4-chloropiperidine are described. In the first route, the key thionyl chloride mediated chlorination reaction features the use of tetrabutylammonium chloride as an additive that effectively suppresses the formation of an elimination-derived side product. In the second route, a novel alternative synthesis of 1-tert-butyl-4-chloropiperidine was developed in which the tertiary butyl group on the nitrogen is efficiently generated through the addition of methylmagnesium chloride to a dimethyliminium salt in 71% overall yield.

Butanes↗

PubMed2003

Aligned nanotubes.

Since the discovery of carbon nanotubes by lijima in 1991, various carbon nanotubes with either a single- or multilayered graphene cylinder(s) have been produced, along with their noncarbon counterparts (for example, inorganic and polymer nanotubes). These nanostructured materials often possess size-dependent properties and show new phenomena related to the nanosize confinement of the charge carriers inside, which leads to the possibility of developing new materials with useful properties and advanced devices with desirable features for a wide range of applications. In particular, carbon nanotubes have been shown to exhibit superior properties attractive for various potential applications, ranging from their use as novel electron emitters in flat-panel displays to electrodes in electrochemical sensors. For many of the applications, it is highly desirable to have aligned/patterned forms of carbon nanotubes so that their structure/property can be easily assessed and so that they can be effectively incorporated into devices. In this Review, we present an overview on the development of aligned and micropatterned nanotubes, with an emphasis on carbon nanotubes.

Journal Article↗