An Easy Method for Pressure Measurement in Microchannels Using Trapped Air Compression in a One-End-Sealed Capillary.

Pressure is one basic parameter involved in microfluidic systems. In this study, we developed an easy capillary-based method for measuring fluid pressure at one or multiple locations in a microchannel. The principal component is a commonly used capillary (inner diameter of 400 µm and 95 mm in length), with one end sealed and calibrated scales on it. By reading the height (h) of an air-liquid interface, the pressure can be measured directly from a table, which is calculated using the ideal gas law. Many factors that affect the relationship between the trapped air volume and applied pressure (papplied) have been investigated in detail, including the surface tension, liquid gravity, air solubility in water, temperature variation, and capillary diameters. Based on the evaluation of the experimental and simulation results of the pressure, combined with theoretical analysis, a resolution of about 1 kPa within a full-scale range of 101.6-178 kPa was obtained. A pressure drop (Δp) as low as 0.25 kPa was obtained in an operating range from 0.5 kPa to 12 kPa. Compared with other novel, microstructure-based methods, this method does not require microfabrication and additional equipment. Finally, we use this method to reasonably analyze the nonlinearity of the flow-pressure drop relationship caused by channel deformation. In the future, this one-end-sealed capillary could be used for pressure measurement as easily as a clinical thermometer in various microfluidic applications.

Design, Synthesis and Biological Evaluation of Potent Human Glyoxalase I Inhibitors.

Several glutathione derivatives bearing the S-(N-aryl-N-hydroxycarbamoyl) or S-(C-aryl-N-hydroxycarbamoyl) moieties (10, 10', 13-15) were synthesized, characterized, and their human glyoxalase I (hGLO1) inhibitory activity was evaluated. Compound 10 was proved to be the effective hGLO1 inhibitor with a Ki value of 1.0 nM and the inhibition effect of compound 10 on hGLO1 was nearly ten-fold higher than that of the strongest inhibitor 2 (Ki=10.0 nM) which has been reported in the field of glutathione-type hGLO1 inhibitors. Its diethyl ester prodrug 10' was able to penetrate cell membrane and had good inhibitory effect on the growth of NCI-H522 cell xenograft tumor model.

Novel bivalent inhibitors with sub-nanomolar affinities towards human glyoxalase I.

The zinc metalloenzyme glyoxalase I (GlxI) catalyzes the glutathione-dependent inactivation of cytotoxic methylglyoxal. Two competitive bivalent GlxI inhibitors, polyBHG2-62 (Ki=1.0 nM) and polyBHG2-54 (Ki=0.3 nM), were synthesized based on the transition-state analog S-(N-bromophenyl-N-hydroxycarbamoyl) glutathione (BHG). The most effective inhibitor, polyBHG2-54, is the first subnanomolar inhibitor of GlxI, and is over 50-fold more potent than BHG itself.

[Embryo-fetus development toxicity of a novel PPAR-δ agonist in rat].

The study aims to investigate the embryo-fetus development toxicity of the novel PPAR-δ agonist HS060098 on SD rats. The pregnant rats that were randomly divided into the solvent control group (1% hydroxypropyl methyl cellulose water solution) and HS060098 suspension groups (10, 30 and 100 mg x kg(-1) xd(-1)) were orally administered with HS060098 suspension or vehicle during the gestation of 6 -15 days (GD6-15). At termination (GD20), female rats were sacrificed. The pregnant females were evaluated by corpora lutea count, implantation sites, existence and death of embryos. Fetal sex, weight, externals, variations and malformations of viscus and skeleton were observed. The results show that there were no significant abnormality in maternal general conditions and fetal appearance as well as viscera, but in the 100 mg x kg(-1) x d(-1) group, the maternal weight gain decreased greatly (P < 0.01) and the skeletal ossification delayed remarkably (P < 0.01); in the 30 mg x kg(-1) xd(-1) group, the fatal and litter number of incompletely ossified sternebrae II was higher than those of the control group (P < 0.05); the skeletal malformations occurred in all dose groups, which indicate that the novel PPAR-δ agonist HS060098 had maternal toxicity and adversely effected fetal skeletal development under the experimental conditions.

A theoretical study of bond selective photochemistry in CH2BrI.

Bromoiodomethane photodissociation in the low-lying excited states has been characterized using unrestricted Hartree-Fock, configuration-interaction-singles, and complete active space self-consistent field calculations with the SDB-aug-cc-pVTZ, aug-cc-pVTZ, and 3-21g** basis sets. According to the results of the vertical excited energies and oscillator strengths of these low-lying excited states, bond selectivity is predicted. Subsequently, the minimum energy paths of the first excited singlet state and the third excited state for the dissociation reactions were calculated using the complete active space self-consistent field method with 3-21g** basis set. Good agreement is found between the calculations and experimental data. The relationships of excitations, the electronic structures at Franck-Condon points, and bond selectivity are discussed.