高产聚-3-羟基丁酸重组大肠杆菌的筛选

将能以葡萄糖为唯一碳源积累P(3HB)的工程菌进行优化筛选,获得6个较高产的菌株,PHB含量最高为69.1%.经丙酸驯化,虽然没有PHBV的积累,但PHB的量均有增加,最高可达71.13%.另外,抗生素对菌体生长及PHB积累有重要影响.     

利用假单胞菌DS1001a降解聚3-羟基丁酸酯制备3-羟基丁酸

利用单因素法和响应面中心试验法对假单胞菌(Psedomonas sp.)DS1001a降解聚3-羟基丁酸酯(PHB)制备3-羟基丁酸(3-HB)的条件进行了优化.结果表明,该菌株降解PHB制备3-HB的最适培养基条件为:0.2%PHB,0.05%NH4Cl,1.01%Na2HPO4·12H2O,0.39%KH2PO4,0.07%MgSO4·7H2O,0.000 5%CaCl2·2H2O;最适培养条件为:培养温度40℃,装液量150mL,接种量1%,初始pH值6.28,培养时间18h.优化后3-HB的质量浓度为1.555mg/mL,回收率为77.75%,是单因素优化后的1.56倍.     

真养产碱杆菌H16突变株利用葡萄糖为碳源高产聚-β-羟基丁酸的研究

利用常规紫外诱变技术〔１〕，处理真养产碱杆菌（Ａｌｃａｌｉｇｅｎｅｓｅｕｔｒｏｐｈｕｓ）Ｈ１６，采用葡萄糖为碳源的选择培养基进行筛选，获得了能高效利用葡萄糖为碳源高产聚－β－羟基丁酸（ＰＨＢ）的突变菌株。摇瓶试验表明，该突变株能利用多种碳源积累ＰＨＢ，ＰＨＢ积累量达６．７ｇ／Ｌ。     

聚(3-羟基丁酸酯-co-4-羟基丁酸酯)的外增塑改性

采用溶剂成膜法制备了柠檬酸三乙酯(TEC)、大豆油和甘油三乙酸酯增塑的聚(3-羟基丁酸酯-co-4-羟基丁酸酯)共混物,考察了增塑剂的种类及其用量对共混物热学和力学性能的影响。用差示扫描量热仪(DSC) 和电子拉力试验机分别测定共混物的热性能和力学性能。结果表明,三种增塑剂中质量分数为5%的TEC对共聚物的增塑改性效果较好,与纯聚酯相比共混物的结晶温度(T_mc)下降了2.0℃,结晶焓(ΔH_mc)基本保持不变。当TEC的质量分数为20%时,聚(3-羟基丁酸酯-co-4-羟基丁酸酯)的T_g下降21℃。TEC共混物能保持15.8MPa的拉伸强度和588%的断裂伸长率。     

聚β-羟基丁酸酯的微生物合成

文章就当前聚β-羟基丁酸酯（PHB）微生物合成的一些研究作一简要的综述，其中包括：产生PHB的主要微生物、PHB微生物合成途径及调控机制、PHB聚合酶的生物化学与分子生物学研究及碳源与营养受限等。     

聚β-羟基丁酸酯的微生物降解

简要地综述了近年来关于聚β-羟基丁酸酯（polyhydloxybutymte以下简称PHB）的微生物降解方面的一些研究成果，包括：降解PHB的菌种及降解能力；PHB的降解过程和分子机制；PHB解聚酶的生物化学与分子生物学研究等。     

聚(3-羟基丁酸酯-co-4-羟基丁酸酯)的土壤降解和酶降解

采用溶剂涂膜法制备了共聚组成不同的（3-羟基丁酸酯）-（4-羟基丁酸酯）共聚物［poly(3HB-co-4HB)］生物可降解膜。通过土壤和猪胰脂肪酶降解实验,考察了降解过程中样品质量、分子量及表面形态的变化。结果表明,土壤降解和酶降解都经过表面腐蚀过程,无定形态首先降解,样品质量逐渐损失,分子量逐渐减少;结晶度对膜的腐蚀形貌有很大的影响,降解速率都随4HB含量的增加而增加;脂肪酶降解速率比土壤降解速率快,但分子量减少的程度不及土壤降解,并且在降解过程中出现了小分子量的低聚物。     

扩链改性对生物塑料聚(3-羟基丁酸酯-co-4-羟基丁酸酯)性能的影响

以异佛尔酮二异氰酸酯(IPDI)和巴斯夫扩链剂-4370(ADR-4370)为扩链剂,采用熔融挤出法制备扩链改性聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)].使用毛细管流变仪、哈克转矩流变仪、力学性能测试仪及扫描电子显微镜等研究扩链剂种类及添加量对P(3HB-co-4HB)流变性能、熔体加工...     

微生物发酵法生产聚β-羟基丁酸

真养产碱菌（Ａｌｉｃａｌｉｇｅｎｅｓｅｕｔｒｏｐｈｕｓ）Ｍ４０５可以利用葡萄糖生产聚β－羟基丁酸（ＰＨＢ）。对真养产碱菌Ｍ４０５的营养性能以及ＰＨＢ的定性、定量检测进行了研究，并对培养基进行了优化。结果表明，ＰＨＢ经苏丹黑Ｂ梁色呈蓝黑色，它可以用氯仿抽提法提纯，在２３５ｎｍ分光光度计检测。真养产碱菌Ｍ４０５在氮源（（ＮＨ４）２ＳＯ４）达２ｇ·Ｌ－１时，经补料式一步培养后，葡萄糖转化率达到２６９％，此时ＰＨＢ含量最高。     

一种提取聚-β-羟基丁酸酯的新方法

介绍了一种用十二烷基磺酸钠（SDS）结合乙二胺四乙酸（EDTA）从圆褐固氮菌G－3细胞中分离聚－β－羟基丁酸酯（PHB）的方法，并与SDS单独作用菌体分离PHB的方法作了比较，实验发现，前种方法具有更高的效率。主要研究了在不同试剂用量、作用时间、作用温度和pH值等条件下，SDS和EDTA提取PHB的效果，并对分离条件进行了优化。结果表明，在50℃，pH值为7的条件下，用10g/L的EDTA和7g/L的SDS共同作用菌体（含PHB 66％）15min，可使PHB的纯度达到98．75％。     

聚乳酸-聚乙二醇嵌段共聚物及其交联聚氨酯弹性体的性能研究

通过改变聚乙二醇的用量,将丙交酯与聚乙二醇共聚制成嵌预聚体,用二苯基甲烷二异氰酸酯扩链后再用三羟甲基丙烷交联,制得系列聚氨酯型新颖性体。通过对其性能研究表明,随着ＰＥＧ含量的增加,共聚物的特性粘度降低,玻璃化转变温度降低,拉伸强度先升后降;聚氨酯弹性体的玻璃化转变温度降低,拉伸强度降低,而降解速度去加快。     

可生物降解的新型阻垢缓蚀剂聚天门冬氨酸

聚天门冬氨酸是新一代可生物降解的绿色阻垢缓蚀剂。本文对聚天门冬氨酸的合成、性能及发展前景进行了较详细的介绍 ,认为 :间接生产工艺已较成熟 ,直接生产工艺有待发展。     

微波法合成低分子量聚L-乳酸研究

在微波辐射条件下，以L-乳酸为原料抽真空直接合成低分子量聚乳酸。根据微波辐射的特点制作了两口长颈反应釜，考察单体纯度、催化剂种类和用量、聚合时间、聚合温度等因素对聚卜乳酸粘均分子量的影响，确定了最佳工艺；并采用IR、^1HNMR和^13CNMR等测试手段对聚合产物进行了结构表征。     

Enhanced flame-retardant performance of poly (lactic acid) (PLA) composite by using intrinsically phosphorus-containing PLA

The intrinsically phosphorous-containing flame-retardant poly(lactic acid)(P-PLA) was synthesized through the chain extension of L-lactide and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO) derivative, then P-PLA was melt blended with neat PLA to produce flame-retardant PLA composite(FR-PLA). The flame-retardant properties of FR-PLAs were investigated by Limiting Oxygen Index(LOI), UL-94, and Cone Calorimeter Tests, the results indicated that the flame-retardant properties of PLA composites were significantly improved with the addition of P-PLA due to its excellent ability to carbonize and dilute combustible gases. The LOI value of FRPLA10 composite(consisting of 90 wt% neat PLA and 10 wt% P-PLA) increased from 20.5 to 27.8 and UL-94 rating reached up to V-1, the peak heat release rate and total heat release of FR-PLA composite were lower than those of neat PLA. The flame-retardant mechanism of FR-PLA depended on both condensed and gaseous phases,which was confirmed by the FTIR, Raman and TG-FTIR. Besides, the tensile strength of FR-PLA10 slightly decreased from 72.4 to 61.8 MPa, which met the requirements of most practical applications. Therefore, the modification method used in this work presented a feasible approach to prepare FR-PLA composite with satisfactory mechanical property.     

Thermal depolymerization mechanisms of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Thermal degradation processes and decomposition mechanisms of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were investigated by using thermal gravity analysis(TGA), Gel permeation chromatography (GPC), elemental analyzer, pyrolysis-gas chromatography-mass spectrometry (PyGC-MS) and 1H nuclear magnetic resonance (1H NMR). The degradation activation energy was calculated via the dependence of residual mass on isothermal temperature. 1H NMR and PyGC-MS were used to investigate the chemical structure and component proportion of volatile gases and degradation residues which were produced by thermal decomposition, and to infer the process of macromolecular chain scission. Besides, the influence of the factors, such as outfield atmosphere, residual metal ions, on the degradation behaviors of PHBV was also studied. Finally, the PHBV thermal decomposition mechanisms were speculated on the basis of the degradation behaviors of molecular and chemical structure.     

吲哚-3-乙酸、吲哚-3-丁酸和邻菲啉的量子化学计算

通过对吲哚 3 乙酸、吲哚 3 丁酸和邻菲啉的量子化学计算 ,可以对它们与RE(Ⅲ )的配位方式做出定性或半定量的解释     

Protein adsorption on the poly（L-lactic acid） surface modified by chitosan and its derivatives

Surface modification of biomaterials has been adopted over the years to improve their biocompatibility. In this study, aiming to promote hydrophilicity and to introduce natural recognition sites onto poly（L-lactic acid） （PLLA） films, chitosan and its derivatives, carboxymethyl chitosan（CMC） and N-methylene phosphonic chitosan （NPC）, were used to modify the surface of PLLA films by an entrapment method. Radiolabeled （^125I） proteins were used to measure the amount of protein adsorbed to PLLA surfaces. Fibronectin （Fn） was used to study the protein adsorption on the modified PLLA surfaces, including isotherm adsorption and adsorption kinetics of single protein, competitive adsorption of binary proteins system and serum multi-proteins and the desorption behavior in serum solution. The results showed that in the isotherm adsorption, Fn had a larger adsorption capacity on the CS-modified surface at lower concentrations, but had a high adsorption capacity at CMC-modified surface at higher concentrations. In the study of absorption kinetics, Fn had a fastest adsorption equilibrium and a highest equilibrium adsorption capacity at the CS-modified surface, while it was opposite at the PCS-modified surface. When BSA and serum were added, it had the greatest effect on the adsorption of Fn on the PCS-modified surface. After 6 hours soaking in the desorpUon study, Fn had reached desorption equilibrium on all the modified surfaces, which had different effects on the desorption rate and the remaining percentage of Fn.     

In vitro study of poly(ethylene carbonate) as a drug-eluting stent coating

An in vitro feasibility study of the use of poly(ethylene carbonate) (PEC) as a biodegradable coating material for drug-eluting stents is reported, and the performance of PEC is compared with that of poly(lactic-co-glycolic acid) (PLGA). Scanning electron microscopy (SEM) images of PEC and PLGA discs after treatment with an alkaline KO2 solution as a superoxide source showed that the PEC maintained its integrity whereas holes and small particles appeared during the treatment of PLGA. Sirolimus and paclitaxel were loaded into PEC and PLGA in order to study drug release performance. Attenuated total reflectance–infrared (ATR– FTIR) spectroscopy of sirolimus, PEC and the sirolimus-loaded PEC coating showed that no chemical reaction occurred between sirolimus and PEC. The results of atomic force microscopy (AFM) revealed that the mean roughness (Ra) values of the bare metal stent (BMS) and the drugeluting stent (DES) were 2.3 nm and 1.0 nm, respectively. After balloon expansion experiments, no delamination or destruction of the PEC coating was observed. The drug release profile of sirolimus was different from that of paclitaxel when PEC was employed as the drug carrier, and the release curves of sirolimus were different when PEC and PLGA were used as drug carriers. All the experimental results demonstrated that PEC was one of the best potential stent-coating materials.     

聚丙烯酸/蒙脱土纳米复合材料吸附FeCl_3的行为和动力学性能

利用高温快速反应法成功制备聚丙烯酸/蒙脱土高吸水性纳米复合材料.在20~40℃研究聚丙烯酸/蒙脱土纳米复合材料对FeCl3的吸附行为.结果表明,复合材料对FeCl3的室温吸附行为符合Freundlish关系,其单位质量的平衡吸附量Γ=5.31c0.61g;吸附过程为二级反应,1/c与吸附时间t呈良好的线性关系;复合材料吸附FeCl3的反应速率常数为k=1.955×10-6exp(26.025/RT),其吸附过程的表观活化能Ea=-26.025 kJ/mol;复合材料对FeCl3的吸附在较低温度下即能迅速进行,其吸附过程为放热过程.