可降解高分子塑料的发展与应用

介绍了可降解塑料的分类及降解机理,探讨了其发展中存在的问题,并且对可降解塑料的发展前景进行了分析。     

生物质可降解聚氨酯材料的研究进展

综述了近年来生物质可降解聚氨酯材料的种类,主要包括纤维素改性聚氨酯、低聚糖改性聚氨酯、木质素改性聚氨酯、单宁改性聚氨酯、树皮改性聚氨酯、淀粉改性聚氨酯及其它物质改性聚氨酯。     

PHB在生产可降解塑料方面的应用及其微生物累积的研究进展

着重介绍了聚β-羟基丁酸（PHB）的一些性质、用途以及在生产可降解塑料方面的应用情况，同时也介绍了微生物累积PHB的情况，并对微生物累积PHB以及PHB的研究发展提出了一点建议。     

Comparative Assay of Antioxidant Packages for Dimer of Estolide Esters

A series of 26 different antioxidants and commercial antioxidant packages designed for petroleum‐based materials, containing both natural and synthetic‐based materials, were evaluated with dimeric coconut‐oleic estolide 2‐ethylhexyl ester (2‐EH), a bio‐based material. The different antioxidants were categorized into different classes of phenolic, aminic, and blended/others materials. The oxidation onset temperatures (OT) using non‐isothermal pressurized differential scanning calorimetry (PDSC) were measured and recorded under previously reported standard conditions. The aminic series gave the best resistance to oxidation as defined by the PDSC method with OT of 246.6 and 244.7 °C for the best two performers, which was a 38 °C improvement over the uninhibited or unformulated dimer estolide material. The phenolic series, containing most of the naturally occurring antioxidants, was the least successful formulation package for the dimer estolide. The blended/other materials, which were specifically designed for petroleum‐based lubricants, did not have the best OT, since the estolides and other bio‐based materials interact differently than their petroleum counterparts. A number of potential antioxidants have been identified as useful additives for the estolides esters. The OT of the estolide and formulated materials correlated well with other bio‐based materials such as biodiesel.     

Magnetic composite scaffolds of polycaprolactone/nFeHA,for bone-tissue engineering

Magnetic composite scaffolds of polycaprolactone/Fe doped nanohydroxyapatite (PCL/nFeHA) with different composition ratios have been fabricated lyophilization for the purpose of bone-tissue engineering. Magnetic measurements reveal some interaction between the Fe particles that decreases steadily as the nFeHA is diluted in the polymer. All the scaffolds were characterized before and after in vitro degradation for over 28 weeks. The nFeHA nanoparticles decreased the initiation rate of hydrolytic degradation. After 16 weeks degradation, thermograms of the first heating revealed two melting peaks, which could be attributed to the presence of crystals of two different sizes. GPC results indicated that Mw and Mn were unaffected by the degradation with no cleavage of the macromolecular chains.     

原油碱水乳化活性组分研究

对河南油田三种原油中的有机酸和非酸含氧化合物进行了分离鉴定并研究了它们在碱水乳化中的作用。有机酸是引起各原油碱水乳化的活性物质，非酸含氧化合物本身无碱水乳化活性，但对有机酸的乳化活性有协同作用。     

稠油化学降粘技术研究进展

综述了稠油开采、集输和管道输送中使用的化学降粘剂（主要是油溶性聚合物降粘剂）及化学降粘技术。这是国内外研究、开发均很少的一个领域。全文除前言外包括以下四大论题。①油溶性降粘剂降粘技术：原理,降粘剂结构特点及国内油田应用于稠油井采油的一个实例。②油溶性降粘剂：发展简史,结构类型（主要为共聚物降粘剂）及国内外现场应用的11种商品降粘剂（10种用于长距离管输,1种用于稠油井生产）。③在我国油田的应用问题：集输,水乳化降粘（使用水溶性乳化剂）,作为辅助手段的油溶性降粘剂,稠油改质降粘。④研究中存在的问题与方向：油溶性降粘剂的作用机理及合成中的新思路,适当结构的降粘剂与表面活性剂的复配,化学降粘的局限性。参考文献63条。     

Enzymatic transesterification for production of biodiesel using yeast lipases: An overview

Biodiesel has provided an eco-friendly solution to fuel crisis, as it is renewable, biodegradable and a non-toxic fuel that can be easily produced through enzymatic transesterification of vegetable oils and animal fats. Enzymatic production of biodiesel has many advantages over the conventional methods as high yields can be obtained at low reaction temperatures with easy recovery of glycerol. Microbial lipases are powerful biocatalysts for industrial applications including biodiesel production at lower costs due to its potential in hydrolyzing waste industrial materials. Among them, lipases from yeasts, Candida antarctica, Candida rugosa, Cryptococcus sp., Trichosporon asahii and Yarrowia lipolytica are known to catalyze such reactions. Moreover, stepwise addition of methanol in a three step, two step and single step reactions have been developed using yeast lipases to minimize the inhibitory effects of methanol. The latest trend in biodiesel production is the use of whole-cell as biocatalysts, since the process requires no downstream processing of the enzyme. Synthesis of value added products from the byproduct glycerol further reduces the production cost of biodiesel. This review aims at compiling the information on various yeast lipase catalyzed transesterification reactions for greener production of biodiesel.     

Coke Formation from Aircraft Engine Oils: Part II—Effects of Oil Formulation and Surface Composition

This is the second of two papers giving the results of a study undertaken to determine how aircraft engine oil degrades to form coke on oil-wetted surfaces. In part 2 the authors address the impacts of additives (which is related to oil types) and surface materials upon the oil coking process.

In Part 1 of this study, the authors showed that simple laboratory tests involving thin films of oil heated for specified timesltemperatures in open glass vials produced polymer and coke similar to the deposits seen on failed face seals taken from the operating aircraft engines and polymers isolated from used engine oils. Antioxidants inhibit and delay the coke producing reactions. After the antioxidant package is depleted to approximately 10 percent of the original level, the ester basestock undergoes accelerated oxidation to form oil-soluble polymers. As the oil spends additional time at elevated temperature, these polymers increase in molecular weight and undergo minor compositional changes becoming insoluble in the oil, producing deposits. If the time that a thin oil layer spends on a hot surface at elevated temperature can be limited so that the antioxidant does not deplete completely, coking can be prevented. This shifts the focus from coke minimization to coke prevention.

The authors results in Part 2 indicate that oil choice—which is largely a choice of antioxidant package—makes a large difference in how long oil can remain on a hot surface without forming polymer/coke deposits. For the oils studied in Part 2, the capabilities of the oils' antioxidant packages to inhibit coke formation varied 15 fold.

Surface material choice has minimal effect upon the rate of antioxidant depletion. However, once the antioxidant in the oil in a thin layer has become ineffective in inhibiting accelerated oxidation (approximately 10 percent of original concentration), the material the oil resides upon strongly effects the rate of the polymer/coke formation processes. Stainless steel speeds the process compared to a glass substrate.     

Influence of Mg concentration, pH value and specimen parameter on the hemolytic property of biodegradable magnesium

In this study, we first evaluated the hemolytic rate of pure magnesium and MgZn alloy, and the experimental results indicated that both of these two materials showed severe hemolysis. Furthermore, a revised hemolysis test was designed to assess the impact of the Mg²⁺ concentration and the pH value on the hemolytic rate of magnesium. It was found that a Mg²⁺ concentration of 11.4 ppm in the normal saline extract with a pH value of 7.35 or 4.93 did not demonstrate any hemolysis. However, the extract with the same Mg²⁺ concentration but a pH value of 12.01 or 2.48 could result in heavy hemolysis. In addition, compared to the pervious study, it was suggested that there should be a preferred choice between the mass and the surface area of the specimen that used in the hemolysis test according to its different medical applications.