ST-T接枝淀粉的可生化量分析

通过可生化量即生化需氧量（BOD）与化学需氧量（COD）的比值对一种已在市场中得到应用的接枝淀粉（ST-T）进行生物降解性评价。测定结果表明ST-T的可生化量的平均值是0.340,是PVA的27-85倍,也比酸解淀粉的可生化量值略高,具有十分优异的生物降解性。     

天冬氨酸/谷氨酸共聚物的可生物降解性

天冬氨酸/谷氨酸共聚物(PAG)作为一种新型水处理剂,考察其环境友好性十分必要.采用CO2产生法(ISO9439)研究共聚物(PAG)的可生物降解性.结果表明,相对分子质量Mw=3000的共聚物(PAG)10 d和28 d的降解率分别为34%和79%,为易降解阻垢剂;PAG的可生物降解性受谷氨酸比例和共聚物相对分子质量的影响;PAG具有优良可生物降解性的原因可能在于分子中存在较多的—COO-和C—N骨架.研究还发现,Cu2 的存在导致PAG的生物降解性下降,Cu2 抑制了生物酶的活性,而且这种抑制作用不是线性的,可能存在"低剂量效应".     

二级处理出水中有机物的分级特性

为研究二级出水中有机物的化学特性,以哈尔滨市W污水处理厂为研究对象,利用XAD树脂将二级处理出水中的有机物分级为5个组分:疏水性有机酸(HPO-A)、疏水性中性有机物(HPO-N)、过渡亲水性有机酸(TPI-A)、过渡亲水性中性有机物(TPI-N)和亲水性有机物(HPI).采用氯化反应实验、可生物降解溶解性有机碳和尺寸分布测定,以及紫外和红外光谱分析考察二级处理出水中不同有机组分的特性.结果表明:HPO-A是加氯消毒时产生三卤甲烷的主要有机组分.各有机组分中,溶解性有机碳(DOC)(<0.025μm)均是主要的有机碳形式和主要的三卤甲烷前体物.各组分的可生化性为:HPI>TPI-A>HPO-A>TPI-N>HPO-N.各组分的芳香性为:HPO-N>HPO-A>TPI-N>TPI-A>HPI.HPO-N和TPI-N中碳氢化合物的含量较高.在二级处理出水中,HPO-A和HPI的含量相对较高,是主要的有机组分.此外,不同有机组分的化学特性不同.     

煤气废水有机污染物缺氧生物降解性能及机理

为考察煤制气废水3种典型有机污染物(喹啉、吡啶、邻苯二酚)的缺氧生物降解性能及降解途径,利用缺氧驯化污泥作为接种污泥,以硝态氮为电子受体,考察了3种有机物的缺氧降解过程,并利用UV-Vis和GC/MS分析3种物质缺氧降解机理.结果表明:3种污染物对缺氧微生物抑制与毒害作用随初始质量浓度增加而增强;缺氧降解48 h后,剩余底物质量浓度随初始质量浓度增加而增大;3种污染物缺氧生物降解速率常数大小顺序为吡啶邻苯二酚喹啉.缺氧降解中污染物未被完全氧化成CO2和H2O,部分生成了较底物自身降解性更差的中间产物.葡萄糖共基质可以提高难降解污染物缺氧降解性能,且共代谢作用对自身生物降解性差的污染物降解性能的提高更显著.利用UV-Vis和GC/MS分析了污染物缺氧生物降解途径,结果表明,喹啉和吡啶的降解均始于分子羟基化反应.污染物定量结构-生物降解性关系(QSBR)研究表明,3种物质的缺氧降解速率常数Ks与分子连接性指数1Xv和前线最高占据轨道能EHOMO有很好的相关性.     

Biodegradability and improved mechanical performance of polyhydroxyalkanoates/agave fiber biocomposites compatibilized by different strategies

In this work, biocomposites made of polyhydroxyalkanoates (PHA) with natural fibers were produced via compression molding. In particular, polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-hydroxyvalerate (PHBV) were reinforced with 20 wt% of agave fibers. Different compatibilization strategies were investigated to improve the fiber-matrix interaction: fiber surface treatment in PHA solution, fiber surface treatment in maleated PHA solution, fiber propionylation, and extrusion with maleated PHA. The biocomposites were characterized in terms of morphology, mechanical properties, water absorption, and biodegradability by CO₂ production tracking. In general, fiber propionylation was the best strategy for mechanical properties enhancement and water uptake decreasing. Biocomposites with propionylated fibers showed improved flexural strength (170% for PHB and 84% for PHBV). The flexural modulus was also enhanced with propionylated fibers up to 19% and 18% compared to uncompatibilized biocomposites (PHB and PHBV, respectively). Tensile strength increased by 16% (PHB) and 14% (PHBV), and the water absorption was reduced using propionylated fibers going from 6.6% to 4.4% compared with biocomposites with untreated fibers. Most importantly, the impact strength was also improved for all biocomposites by up to 96% compared with the neat PHA matrices. Finally, it was found that the compatibilization did not negatively modify the PHA biodegradability.     

Biodegradable and conductive hyperbranched terpolymers based on aliphatic polyester,poly(D,L-lactide), and polyaniline used as scaffold in tissue engineering

Designing the novel conductive and biodegradable scaffolds based on star-like hyperbranched terpolymers of aliphatic polyester–poly(D,L-lactide)–polyaniline (S-HAP–PLA–PANI) was the purpose of this research. The electroactivity of tissue engineering scaffold, which in the current work was for the presence of PANI, is an essential factor in its performance because the electrical signals are the pivotal physiological stimuli that control the adhesion and differentiation of various cell types. Star-shaped polymers have attracted conspicuous attention, thanks to their low-cost, well-defined highly functionalized structures and low crystallinity, and they also could be an interesting alternative to the linear analogs for their interaction with surrounding tissue and faster degradation rate. In the present work, after 12 weeks, the mass loses for S-HAP–PLA–PANI sample were calculated to be 45%. Scaffolds based on S-HAP–PLA–PANI/PLA nanofibers having the average diameter of 70–200?nm and electrical conductivity of 0.05 S cm^?1 imitated the natural microenvironment of extra cellular matrix to regulate the cell attachment, proliferation, and differentiation.     

润滑油生物降解性的评定方法

 参参照CEC（欧洲协调委员会）标准（CEC L-33-A-93），利用四氯化碳（CCl4）作萃取剂，以天津纪庄子污水处理厂的活性污泥中的活性菌为实验接种体进行了润滑油生物降解评定方法验证实验。盛有矿物介质、实验油和接种体的烧瓶与含有有毒实验油的白瓶同时进行为期21d保温培养实验，并用含有参比物质的烧瓶代替实验油进行平行实验。保温培养完成后，烧瓶中的物质通过声波振荡、酸化，再用CCl₄萃取。然后，用红外光谱分析萃取液，测量CH₃-CH₂-的C-H伸缩震动吸收峰（在2930±10cm^-1）的强度，用来计算毒化瓶和实验瓶中残留油量，从而计算实验油的生物降解率。结果表明，该方法测定润滑油的生物降解率误差在5.5%以内。     

Evaluation of Biodegradation of Pineapple Leaf Fiber Reinforced PVA Composites

Composites of polyvinyl alcohol (PVA) reinforced with different weight percentages of pineapple leaf fibers (PALF) were fabricated and evaluated for biodegradation by soil burial test and plate test. FTIR analysis indicated the existence of a chemical interaction between PVA and PALF. The water uptake study showed that the composites with higher fiber content displayed high tensile strength and brittleness but possessed lower water uptake potential. In the soil burial test, the composites with low matrix to filler ratios exhibited higher rates of degradation as evident by the associated decrease in molecular weights. Plate test performed using Pseudomonas putida showed that the composites were susceptible for degradation by bacteria. The results of this study indicated that PALF-reinforced PVA composites were completely biodegradable and could find potential applications in industries such as agriculture and packaging and safely disposed after use without causing environmental damage.     

Cuttlebone-Derived Organic Matrix: A Facile Periosteum Substitute for Bone Regeneration

Artificial periosteum has become a novel strategy for bone healing. Several efforts are made to develop novel periosteum substitutes with excellent osteogenesis and angiogenesis performance. The problem, however, is that many inconveniences, such as unattainable materials and complex preparation processes, limit its clinical application. In this study, cuttlebone-derived organic matrix (CDOM) film is developed as a facile obtained artificial periosteum with good bioactivity, biodegradability, and biosafety. In this study, CDOM films are prepared by etching calcium carbonate of cuttlebone with hydrochloric acid (HCl), phosphoric acid (H₃PO₄), and ethylenediaminetetraacetic acid (EDTA), respectively. CDOM films possess “S” oriented grooves on one surface, providing suitable space for survival, adhesion, and proliferation of rat mesenchymal stem cells and human umbilical vein endothelial cells. Among three CDOM films, CDOM-EDTA is the most efficient at enhancing bone regeneration in vivo, with an increase in neovascularization and new bone formation. Meanwhile, CDOM-EDTA is degradable in two months and of extremely low toxicity. There is a great deal of promise in the future for this novel periosteum substitute to be used for bone defect healing in clinical settings.