Poly-3-hydroxybutyrate （PHB） can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and...Poly-3-hydroxybutyrate （PHB） can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and plentiful not only as natural gas, but also as biogas. Methanol can also maintain methanotrophic activity in some conditions. The methanotrophic strain Methylosinus trichosporium IMV3011 can accumulate PHB with methane and methanol in a brief nonsterile process. Liquid methanol （0.1%） was added to improve the oxidization of methane. The studies were carried out using shake flasks. Cultivation was performed in two stages： a continuous growth phase and a PHB accumulation phase under the conditions short of essential nutrients （ammonium, nitrate, phosphorus, copper, iron （Ⅲ）, magnesium or ethylenediamine tetraacetate （EDTA）） in batch culture. It was found that the most suitable growth time for the cell is 144 h. Then an optimized culture condition for second stage was determined, in which the PHB concentration could be much increased to 0.6 g/L. In order to increase PHB content, citric acid was added as an inhibitor of tricarboxylic acid cycle （TCA）. It was found that citric acid is favorable for the PHB accumulation, and the PHB yield was increased to 40% （w/w） from the initial yield of 12% （w/w） after nutrient deficiency cultivation. The PHB produced is of very high quality with molecular weight up to 1.5 × 10^6Da.展开更多
Poly（L-lactide-co-caprolactone）（85-15）[P（LLA-CL）（85-15）] was synthesized from high purity L-lactide and e-caprolactone using tin octoate as initiator by ring-opening polymerization, and characterized by infrar...Poly（L-lactide-co-caprolactone）（85-15）[P（LLA-CL）（85-15）] was synthesized from high purity L-lactide and e-caprolactone using tin octoate as initiator by ring-opening polymerization, and characterized by infrared spectrum and IH-NMR spectrum. The synthesized P（LLA-CL）（85-15） is a random copolymer. The influences of polymerization temperature, polymerization time, dosage of initiator and polymerization pressure on the weight average molecular weight and the polydispersity index of P（LLA-CL）（85-15） were investigated. The optimum preparation conditions of P（LLA-CL）（85-15） are： the polymerization pressure is less than 0.5 Pa, the polymerization temperature is 130 ~C, the n（M）/n（I） ratio is 8 000/1, and the polymerization time is 36 h. Under the condition, the weight-average molecular weight of prepared P（LLA-CL）（85-15） is 65.6x 104, and molecular weight distribution coefficient is 1.15.展开更多
P（LLA-CL）（75/25） （poly（L-lactide-co-caprolactone）（75/25）） was synthesized from high purity L-lactide and e-caprolactone using tin octoate as initiator by ring-opening polymerization, and characterized by inf...P（LLA-CL）（75/25） （poly（L-lactide-co-caprolactone）（75/25）） was synthesized from high purity L-lactide and e-caprolactone using tin octoate as initiator by ring-opening polymerization, and characterized by infrared spectrum and ^1-NMR （^1H proton spectrum of nuclear magnetic resonance） spectrum. The synthesized P（LLA-CL）（75/25） is a random copolymer. The influences of polymerization temperature, polymerization time and dosage of initiator on the weight average molecular weight and the polydispersity index of P（LLA-CL）（75/25） were investigated. The optimum preparation condition of P（LLA-CL）（75/25） was： the polymerization pressure is less than 0.5 Pa, the polymerization temperature is 125℃, the n（M）/n（I） ratio is 8,000/1, the polymerization time is 36 h. Under the condition, the weight-average molecular weight of prepared P（LLA-CL）（75/25） is 45.3×10^4, and molecular weight distribution coefficient is 1.24.展开更多
Carbon black （CB）/polymer composites with high refractive index （RI） were fabricated from poly（vinyl alcohol） （PVA） and covalently functionalized nano-CB （PVA-es-CB） by simple esterification reaction. Transm...Carbon black （CB）/polymer composites with high refractive index （RI） were fabricated from poly（vinyl alcohol） （PVA） and covalently functionalized nano-CB （PVA-es-CB） by simple esterification reaction. Transmission electron microscopy showed that tmifonn aggregates of PVA-es-CB nanoparticles with a size smaller than I00 nm formed in the nanocomposite films. Ellipsometric measurements indicated that the PVA-es-CB/PVA composite films had a RI in the range 1.520-1.598 linearly increased with the PVA-es-CB volume content. Theoretical equation based on Lorentz-Lorenz theory provided reasonably close estimation of the refractive indices to the experimentally observed values. The hybrid films also revealed relatively good surface planarity, thermal stability and optical transparency.展开更多
基金New Century Excellent Talents in University of China(NCET-05-0358)the National Natural Science Foundation of China(20625308)
文摘Poly-3-hydroxybutyrate （PHB） can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and plentiful not only as natural gas, but also as biogas. Methanol can also maintain methanotrophic activity in some conditions. The methanotrophic strain Methylosinus trichosporium IMV3011 can accumulate PHB with methane and methanol in a brief nonsterile process. Liquid methanol （0.1%） was added to improve the oxidization of methane. The studies were carried out using shake flasks. Cultivation was performed in two stages： a continuous growth phase and a PHB accumulation phase under the conditions short of essential nutrients （ammonium, nitrate, phosphorus, copper, iron （Ⅲ）, magnesium or ethylenediamine tetraacetate （EDTA）） in batch culture. It was found that the most suitable growth time for the cell is 144 h. Then an optimized culture condition for second stage was determined, in which the PHB concentration could be much increased to 0.6 g/L. In order to increase PHB content, citric acid was added as an inhibitor of tricarboxylic acid cycle （TCA）. It was found that citric acid is favorable for the PHB accumulation, and the PHB yield was increased to 40% （w/w） from the initial yield of 12% （w/w） after nutrient deficiency cultivation. The PHB produced is of very high quality with molecular weight up to 1.5 × 10^6Da.
基金Supported by the National Natural Science Foundation of China (No.20976017)the Technological Project of Hunnan Province(Nos.2010FJ3098 and 2010NK3001)the project funded by Hunnan Province Education Office(No.11C0018)
文摘Poly（L-lactide-co-caprolactone）（85-15）[P（LLA-CL）（85-15）] was synthesized from high purity L-lactide and e-caprolactone using tin octoate as initiator by ring-opening polymerization, and characterized by infrared spectrum and IH-NMR spectrum. The synthesized P（LLA-CL）（85-15） is a random copolymer. The influences of polymerization temperature, polymerization time, dosage of initiator and polymerization pressure on the weight average molecular weight and the polydispersity index of P（LLA-CL）（85-15） were investigated. The optimum preparation conditions of P（LLA-CL）（85-15） are： the polymerization pressure is less than 0.5 Pa, the polymerization temperature is 130 ~C, the n（M）/n（I） ratio is 8 000/1, and the polymerization time is 36 h. Under the condition, the weight-average molecular weight of prepared P（LLA-CL）（85-15） is 65.6x 104, and molecular weight distribution coefficient is 1.15.
文摘P（LLA-CL）（75/25） （poly（L-lactide-co-caprolactone）（75/25）） was synthesized from high purity L-lactide and e-caprolactone using tin octoate as initiator by ring-opening polymerization, and characterized by infrared spectrum and ^1-NMR （^1H proton spectrum of nuclear magnetic resonance） spectrum. The synthesized P（LLA-CL）（75/25） is a random copolymer. The influences of polymerization temperature, polymerization time and dosage of initiator on the weight average molecular weight and the polydispersity index of P（LLA-CL）（75/25） were investigated. The optimum preparation condition of P（LLA-CL）（75/25） was： the polymerization pressure is less than 0.5 Pa, the polymerization temperature is 125℃, the n（M）/n（I） ratio is 8,000/1, the polymerization time is 36 h. Under the condition, the weight-average molecular weight of prepared P（LLA-CL）（75/25） is 45.3×10^4, and molecular weight distribution coefficient is 1.24.
基金financially supported by the National Natural Science Foundation of China(No.50733001)Natural Science Foundation of Shanghai(No.11ZR1409500)Shanghai Key Laboratory Project(No.08DZ2230500)
文摘Carbon black （CB）/polymer composites with high refractive index （RI） were fabricated from poly（vinyl alcohol） （PVA） and covalently functionalized nano-CB （PVA-es-CB） by simple esterification reaction. Transmission electron microscopy showed that tmifonn aggregates of PVA-es-CB nanoparticles with a size smaller than I00 nm formed in the nanocomposite films. Ellipsometric measurements indicated that the PVA-es-CB/PVA composite films had a RI in the range 1.520-1.598 linearly increased with the PVA-es-CB volume content. Theoretical equation based on Lorentz-Lorenz theory provided reasonably close estimation of the refractive indices to the experimentally observed values. The hybrid films also revealed relatively good surface planarity, thermal stability and optical transparency.
