In this paper, the multiwalled carbon nanotubes (MWCNTs) were modified with chitosan (CS) by using low temperature plasma grafting technique (denoted as MWCNT-CS). The prepared MWCNTs and MWCNT-CS were characterized by SEM, TEM, FTIR and Raman spectroscopy in detail and the results suggested that CS molecules were successfully grafted on the surfaces of MWCNTs. The materials were applied as adsorbents in the removal of U(VI) ions from large volumes of aqueous solutions as a function of environmental conditions. The removal of U(VI) from aqueous solution to MWCNTs and MWCNT-CS increased with increasing pH values at pH < 7, and then decreased with increasing pH values at pH > 7. The sorption of U(VI) on MWCNTs and MWCNT-CS was strongly dependent on pH and independent of ionic strength. The sorption of U(VI) on MWCNTs and MWCNT-CS was dominated by inner-sphere surface complexation rather than by ion exchange or outer-sphere surface complexation. The surface grafted chitosan molecules can enhances U(VI) sorption on MWCNTs obviously, which was also evidenced from the XPS spectroscopy analysis. The results of high sorption capacity of U(VI) on MWCNT-CS suggest that the MWCNT-CS nanomaterial is a suitable candidate in the preconcentration of U(VI) ions from large volumes of aqueous solutions. 相似文献
A liquid chromatographic method was developed for the simultaneous quantification of four major active components in tobacco (Nicotiana tobaccum L.) wastes. Samples were extracted with 70% v/v aqueous methanol, four compounds including chlorogenic acid, cryptochlorogenic acid, neochlorogenic acid and caffeic acid were identified and determined by using LC coupled to electrospray tandem mass spectrometry and LC–UV method, respectively. Separation in LC–UV was on an Alltima C18 column (250 mm × 4.6 mm i.d.; 5 μm) with a mobile phase consisting acetonitrile: ammonium acetate buffer (pH 4.5) (5:95 v/v), at a flow rate of 1.0 mL min−1, detected at 327 nm. Four regression equations showed good linear relationships (r2 > 0.999) between the peak area of each marker and concentration. The method has good repeatability and precision, the intra-day and inter-day RSD for both retention time and peak area was less than 1.0%. The recoveries, measured at three concentration levels, varied from 96.33 to 101.10%. The LOD (S/N = 3) and LOQ (S/N = 6) were less than 0.010 and 0.795 μg·mL−1, respectively. This assay was successfully applied to the determination of four active compounds in ten samples. The results indicated that the developed assay method was rapid, accurate, reliable and could be readily utilized as a quantitative analysis method for various of tobacco wastes.
A series of 5'-phenyl-3'H-spiro[indoline-3,2'-[1,3,4]thiadiazol]-2-one analogs were synthesized and their Bcl-2 protein inhibitory activities were studied. The lead compound was originally identified using a fluorescence polarization-based competitive binding assay. Among the 10 compounds investigated, 1k showed good binding affinities to Bcl-xL and Mcl-1, with inhibition constants of 8.9 mmol/L and 3.4 μmol/L, respectively. While compound 1c achieved tight binding affinities to Bcl-xL (Ki = 0.16 μmol/L), has the potential to be a new lead compound. 相似文献
Temperature was one of the important environmental factors affecting the biosynthesis of docosahexaenoic acid (DHA; C22:6,
ω−3). Generally, a low temperature would slow the strain growth, but promote the accumulation of unsaturated fatty acids.
According to this information, the effects of temperature and different two-stage temperature shifting strategies on fatty
acid production and DHA content of the marine fungoid protist, Schizochytrium sp. HX-308, were investigated in this study. Finally, the highest DHA percentage was up to 51.98% (per total fatty acids)
with the DHA production of 6.05% (per dry cell weight), which was obtained with the method of shifting temperature from 30 °C
for 32 h to 20 °C for 12 h. 相似文献