Time filter

Source Type

Sun L.-T.,Polytechnic University of Mozambique | Zhang Y.-X.,Polytechnic University of Mozambique | Zhang P.-F.,Shaanxi Entry Exit Inspection and Quarantine Bureau
Wool Textile Journal | Year: 2013

It reported that the temperature influence on the structure and properties of silk fibers at present situation. With the treatment in the high temperature for silk fiber, β-sheet structure relative content decreased, while the α-helix and random coil structure had a tendency to rise, high temperature had great influence on fiber inter-fibrillar supramolecular structure, formed apparent stripes and groove structure on the fiber surface, yellow index increased, strength and elongation percentage decreased. With the low temperature freezing treatment, the water molecules of crystallization in fresh cocoon, made the bonding performance between the silk sericin become weaken, Cocoon reelability percentage increased, appeared microporous structure on the fiber surface after freezing, so that it made the fiber surface activity increase, the moisture absorption and antibacterial ability increase. With treatment for silk fabrics in the freezing, the permeability of the fabric was increased obviously, but the strength had a downward trend along with the time prolonged. Source

Zhang J.,Northwest University, China | Liu Y.-F.,Northwest University, China | Bo L.,Northwest University, China | Qiao C.-A.,Shaanxi Entry Exit Inspection and Quarantine Bureau
Journal of Applied Polymer Science | Year: 2011

Dopamine (DA) was covalently linked via succinic anhydride spacers to poly(ethylene glycol)s (PEGs) with average molecular weights of 4000 (PEG4000), 6000 (PEG6000), and 10,000 (PEG10000). The chemical modification of the PEGs was conducted by a two-step protocol: (1) the preparation of PEG having carboxylic end groups and (2) the synthesis of PEG4000-DA, PEG6000-DA, and PEG10000-DA. The controlled drug-release studies were performed in pH 1.1, 7.4, and 9.0 buffer solutions, The results demonstrate that under the same conditions, the rate of hydrolysis for PEG10000-DA was the slowest among three prodrugs, and a greater amount of DA could be detected being released from the prodrug matrices in the presence of α-chymotrypsin in a buffer solution with pH 8.0. Also, these novel prodrugs could slowly release the active drug molecules and improve the pharmacokinetics of DA. © 2011 Wiley Periodicals, Inc. Source

Zhang J.,Northwest University, China | Liu Y.-F.,Northwest University, China | Liu L.-X.,Northwest University, China | Zhang Y.-Z.,Northwest University, China | And 2 more authors.
Journal of Applied Polymer Science | Year: 2012

Poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) and its drug conjugates are some of the most intensively investigated drug-delivery systems. Metaxalone (Met) was covalently linked to PHPMA via a spacer, and the procedure of the chemical modification for PHPMA was conducted by a two-step protocol: (1) synthesis of PHPMA with different molecular weights and (2) synthesis of PHPMA-Met. The Met content in the conjugate could reach 18%. The controlled drug-release studies were performed in buffer solutions with pH values equal to 1.1, 7.4, and 10.0. The results demonstrate that the rate of hydrolysis for PHPMA-Met was the slowest at pH 1.1, and a greater amount of Met was detected releasing from prodrug matrices in the presence of enzyme in a buffer solution at pH 8.0. It was also found that the novel prodrug effectively improved Met's pharmacokinetics and, furthermore, markedly increased its half-life period. Copyright © 2012 Wiley Periodicals, Inc. Source

Jiang W.,University of Sichuan | Zou H.,University of Sichuan | Fu C.,Shaanxi Entry Exit Inspection and Quarantine Bureau | Lei J.,University of Sichuan | And 2 more authors.
Industrial and Engineering Chemistry Research | Year: 2014

Biodiesel is a promising alternative biofuel, but the treatment of wastewater containing alkali catalyst and glycerol discharged from the washing unit operation increases the cost significantly. Here a novel continuous biodiesel production process with trace-amount alkali as the catalyst under the methanol subcritical condition was proposed and investigated. The optimal operation conditions of preliminary batch reaction experiment are temperature of 200 °C, catalyst concentration of 513 mg/kg, reaction time of 38 min, molar ratio of methanol to oil of 11.9:1, and system pressure of 1.5 MPa. The one-step conversion of raw oil in a batch reactor can reach up to 85.5%. The alkali residue in the biodiesel product can be further reduced by removing the methanol and washing by glycerol instead of by acid or water. The optimal weight ratio of glycerol to biodiesel is 1.5:1, and the residual alkali in the final ester product is about 4.6 mg/kg. The simulation and bench scale continuous experiment based on the optimal batch operation parameters confirmed that the biodiesel produced by the process is qualified well up to the Chinese standard of biodiesel, and the K+ concentration in biodiesel was less than 3.0 mg/kg. The economic evaluation showed that this new process is more economically feasible than the traditional processes. © 2014 American Chemical Society. Source

Zhang W.-K.,Chinese Institute of Clinical Medical Sciences | Wang S.-B.,Peking Union Medical College | Fu C.-Y.,Shaanxi Entry Exit Inspection and Quarantine Bureau | Li P.,Chinese Institute of Clinical Medical Sciences | Xu J.-K.,Beijing University of Chinese Medicine
Zhongguo Zhongyao Zazhi | Year: 2013

Nine compounds were isolated and purified by column chromatographic techniques including macroporous resin, silica gel, ODS, Sephadex LH-20, and preparative reversed-phase HPLC. Their structures were elucidated as taxifolin (1), naringenin (2), chalconaringenin (3), acacetin (4), quercetin 3-O-β-D-galactopyranoside (5), 6-prenylnaringenin (6) xanthohumol (7), desmethylxanthohumol (8), xanthohumol B (9) on the basis of MS and NMR spectroscopic data analysis. Compounds 1-5 were isolated from Humulus lupulus for the first time. Source

Discover hidden collaborations