Magnetostratigraphic dating of mammalian fossils in Junggar Basin；northwest China

IEECAS SKLLQG

The inhibitory effect of intestinal bacterial metabolite of ginsenosides on CYP3A activity

The intestinal bacterial metabolites of ginsenosides are responsible for the main pharmacological activities of ginseng. The purpose of this study was to find whether these metabolites influence hepatic metabolic enzymes and to predict the potential for ginseng-prescription drug interactions. Utilizing the probe reaction of CYP3A activity, testosterone 6beta-hydroxylation, the effects of derivatives of 20(S)-protopanaxadiol and 20(S)-protopanaxatriol families on CYP3A activity in rat liver microsomes were assayed. Our results showed that ginsenosides from the 20(S)-protopanaxadiol and 20(S)-protopanaxatriol family including Rb-1, Rb-2, Rc, Compound-K, Re, and Rg(1), had no inhibitory effect, whereas Rg(2), 20(S)-panaxatriol and 20(S)-protopanaxatriol exhibited competitive inhibitory activity against CVP3A activity in these microsomes with the inhibition constants (K) of 86.4+/-0.8mum, 1.7+/-0.1mum, and 3.2+/-0.2 mum, respectively. This finding demonstrates that differences in their chemical structure might influence the effects of ginsenosides on CYP3A activity and that ginseng-derived products might have potential for significant ginseng-drug interactions.

不同光强条件下树木释放N_2O的研究

首次采用封闭罩法 ,对阳生树木 (水曲柳、红松和赤杨 )及阴生树木 (椴树 )的连体及离体枝叶在不同光强下的N2 O释放进行了野外原位观测 .结果表明 ,阳生树木与阴生树木的N2 O释放对光的反应不同 .阳生树木的N2 O释放受光强的调节规律同以往对农作物等的研究结果一致 ;而阴生树木椴树的N2 O释放速率在强光下N2 O释放较多 ,弱光下释放减少甚至吸收大气N2 O ,其N2 O释放速率与光强呈显著线性正相关关系 .

Sensing H2O2 with layer-by-layer assembled Fe3O4-PDDA nanocomposite film

It was found that Fe3O4 nanoparticles (Fe3O4 NPs) possess intrinsic enzyme mimetic activity similar to that found in natural peroxidase. Here, we applied Fe3O4 NPs to the construction of efficient electrochemical sensor to detect the concentration of hydrogen peroxide. The sensor was fabricated with layer-by-layer assembly of Fe3O4 NPs and poly(diallyldimethylammonium chloride) (PDDA) through the electrostatic interaction, and the multilayer film was characterized with UV-vis absorption spectra, atomic force microscopy, and cyclic voltammetry.

Effect of cavitations on brittle-ductile transition of particle toughened thermoplastics

In this study, we established a correlation between cavitations volume and the brittle-ductile transition (BDT) for particle toughened thermoplastics. The brittle-ductile transition temperature (T-BD) was calculated as a function of T* and interparticle distance (ED), respectively, where T* was a parameter related to the volume of cavitations. The results showed that the smaller the cavitations volume, the higher the brittle-ductile transition temperature. The calculations correlated well with the experimental data. With respect to rubber particle, the rigid particle was too hard to be voided during deformation, thereby the TED of the blend was much higher than that of rubber particle toughened thermoplastic. This was a main reason that rubber particle could toughen thermoplastics effectively, whereas rigid particle could not.

Determination of ascorbic acid by flow injection chemiluminescence suppression method

chemiluminescence suppression method for the determination of ascorbic acid based on Luminol-KIO4-H2O2-ascorbic acid system was established. The linear range for ascorbic acid is 1.0 x 10(-7) similar to 1.0 x 10(-5) mol/L and the detection limit is 6.0 x 10(-8) mol/L. The relative standard deviation (n = 11) is 1.0% for 8.0 x 10(-7) mol/L ascorbic acid. The method has been used to determine the content of ascorbic acid in tablets and injections with satisfactory results.

流动注射化学发光抑制法测定抗坏血酸

基于抗坏血酸对Ｌｕｍｉｎｏｌ－ＫＩＯ４－Ｈ２Ｏ２体系化学发光反应的抑制作用，建立了化学发光抑制快速测定抗坏血酸的新方法。该方法线性范围为 １．０ × １０－７～ １．０ × １０－５ ｍｏｌ／Ｌ，检出限为６．０× １０－８ｍｏｌ／Ｌ，对８．０× １０－７ｍｏｌ／Ｌ抗坏血酸 １１次平行测定的相对标准偏差为 １．０％。用于维生素Ｃ片剂及注射液中抗坏血酸含量的测定，结果令人满意。