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941.
《先进技术聚合物》2018,29(1):623-631
In this study, poly(1‐butyl‐3‐vinylimidazolium bromide) (PBVIm‐Br) was grafted onto the poly(vinyl chloride) (PVC) membrane surface via a 2‐step atom transfer radical polymerization (ATRP) reaction. Poly(2‐hydroxyethylmethacrylate) (PHEMA) was grafted onto the membrane surface by aqueous ATRP reaction; then, BVIm‐Br was introduced onto the surface of the PHEMA‐modified PVC membrane through traditional ATRP reaction. The analysis of surface chemistry confirmed the successful grafting of PHEMA and PBVIm‐Br on PVC membrane surface, and the grafting density (GD) of PBVIm‐Br gradually increased as the grafting time was prolonged. The modified membrane exhibited a positive charge and significantly enhanced surface hydrophilicity. The static water contact angle of the membrane surface decreased from 92.3° to 51.6° as the GD of the PBVIm‐Br brushes increased. Filtration experiments indicated that the water flux of the modified membrane increased with increasing GD, and their recovered fluxes were more than twice than the original. In addition, the total fouling ratio of the membranes decreased from 89% in M0 to 67% in M5, and most of the fouling was reversible as the GD of PBVIm‐Br brushes increased. These results indicated that the positive charged poly(ionic liquid) brushes featuring hydrophilic properties would have potential applications in membrane separation. 相似文献
942.
Lead sulphide (PbS) nano-sculptured thin films (nSTFs) are prepared for the first time using glancing angle deposition technique by physical vapour deposition process. An anisotropic morphology is obtained, which provides an orientational effect. Due to this anisotropic nature of PbS nSTF an attempt has been made to check its effect on the alignment of nematic liquid crystals (LCs). Two different LC devices were fabricated, that is, anti-parallel aligned or electrically-controlled birefringence and hybrid twisted nematic. It is noticed that in both types of devices, good alignment is obtained with high extinction and contrast. A significant effect of these alignments on the electro-optic properties of the LC is reported such as the threshold voltage, response time and contrast ratio. 相似文献
943.
Kai-Chun Chang 《液相色谱法及相关技术杂志》2018,41(8):445-450
The bioequivalence of two Florfenicol (FF) products in pigs was evaluated. A 2?×?2 crossover trial with a 14 days wash-out period was performed. The pigs were orally administered in a single dose (2?mg/kg b.w of FF). Serum samples were analyzed using a liquid chromatography-tandem mass spectrometry method. The limit of quantification was 0.1?ng/mL, and the calibration range was 1.0–100.0?ng/mL. Furthermore, intraday and interday were 5.43–9.09% and 6.23–9.68%, respectively. The areas under the curve (AUC0–48) for the test product B of FF and reference product A were 7289.61?±?1750.44 and 6545.01?±?2766.25?h?×?ng/mL, respectively. The highest concentrations of FF in the serum (Cmax) were 726.05?±?211.77 and 641.97?±?117.94?ng/mL. The mean retention times (MRT) was 7.91?±?1.98 and 7.76?±?2.89?h while the half-lives (T1/2) were 4.07?±?1.71 and 4.99?±?3.30?h. From the analysis of variance results, the p values of Cmax and AUC0–∞ for the 90% confidence interval were 0.492 and 0.320 (p?>?0.05), respectively. A comparison between the test product and the reference product showed no significant difference. Both products showed bioequivalence after being administered in pigs. 相似文献
944.
Alireza Bandegi Kyungtae Kim Reza Foudazi 《Journal of polymer science. Part A, Polymer chemistry》2021,59(20):2334-2344
In this work, we investigate the effect of morphology and segmental dynamics on ion transport in polymerized lyotropic liquid crystals (polyLLCs) containing 1-butyl-3-methylimidazolium tetrafluoroborate as ionic liquid (IL). We demonstrate that two important factors, which affect ion conduction in polyLLCs, are grain size and chain density at the interface. The polyLLC with large grain size (70 nm) shows significant reduction in ion conductivity (one order of magnitude) compared to its homopolymer/IL mixture. However, the polyLLC with small grain size (20 nm) has little difference in ion conductivity compared to its homopolymer/IL mixture. It is observed that decreasing the chain density enhances the interaction of IL with polymer chains and consequently slows the relaxation of polymer chains. In addition, comparing the dynamics of polymer chains in mixtures of homopolymer/IL and templated LLC mesophases shows that the confinement in LLC structure prolongs the relaxation of polymer chains. 相似文献
945.
Summary The enantiomers of diphenylalanine (DPA) were well separated by chiral HPLC and NMR spectroscopy on the chiral stationary
phase (CSP) derived from (18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-TA). The chromatographic parameters such as separation
factors and retention times were greatly influenced by the mobile phase conditions. The (+)-18-C-6-TA used in the CSP was
also employed as a chiral solvating agent for the enantiodiscrimination of the DPA enantiomers by NMR spectroscopy. The proton
of the DPA analyte showing the chemical shift nonequivalences was used in determining the enantiomeric composition of the
analyte. 相似文献
946.
947.
Summary Column switching methods are described which demonstrate an alternative approach to the reduction of analytical time in HPLC.
Although most methods use a combination of techniques, it has been possible to group them into major categories involving
column cleanup, sample cleanup, multicolumn methods and boxcar chromatography.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
948.
Summary The separation of poly(styrene-co-acrylonitrile) is presented in open tubular stainless steel columns and columns packed with
non-porous glass beads. Furthermore separation on a short silica packed column proved to be better than on a similar longer
column. A definition of the term high performance precipitation liquid chromatography is suggested for gradient elution with
sample injection into a starting eluent which is a nonsolvent for the copolymer under investigation. The choice of a suitable
solvent-nonsolvent combination is of essential importance. 相似文献
949.
K. Jones 《Chromatographia》1988,25(7):577-581
Summary The flexibility of process scale high performance liquid chromatography is demonstrated by three examples of reversed-phase
separations (a) a standard purification (b) isolation of trace compounds, and (c) recovery from crystallisation mother liquors.
It was shown that a material, thought to be acceptably pure, contained a toxic impurity, and a remaining impurity, a previously
unseen component of potential therapeutic interest. Favourable cost data were indicated for example (3).
This work was conducted in the Chemical Technology Unit, University of Manchester Institute of Science and Technology, PO
Box 88, Manchester M6O 1OD, UK. 相似文献
950.
Summary The addition of appropriate concentrations of an organic amine and an alkylsulphonate to the mobile phase in reversed-phase, ion-pair liquid chromatography can introduce unique selectivity in to the chromatographic system allowing separation of complex mixtures of basic, acidic and neutral compounds. As an example, the methodology for a specific stability-indicating determination of propantheline bromide, a quaternary ammonium anticholinergic agent, on several reversedphase stationary phases, was developed. The retention mechanism was studied and it was concluded that both ion-interaction processes and ion-exchange processes were involved in the separation technique developed with two counterions of opposite charge in the eluent. 相似文献