洋葱状富勒烯的提纯研究

以石墨粉为碳源, Al为催化剂, 采用真空热处理法制备了平均粒径为15～35 nm的洋葱状富勒烯(OLFs).并用CS₂分离和空气氧化法对得到的OLFs初产品进行了提纯处理.高分辨透射电镜(HRTEM)、X射线衍射(XRD)、热重分析(TGA)对提纯前后样品的分析表明, CS₂分离处理可有效去除初产品中裸露的金属催化剂微粒,然后在空气中610 ℃焙烧200 min,可基本去除无定型碳,并大量去除了石墨状碎片等碳杂质, OLFs的纯度在50％(体积分数)以上.     

Isometric crystallization of stretched poly(e-caprolactone) sheets for medical applications

Low melting temperature thermoplastic sheets based on poly(e-caprolactone) (PCL) can be formed directly on the patient and are used as immobilization device (mask) in the radiation therapy. The immobilization mask is allowed to harden in isometric conditions on the body at room temperature. A new method for isometric crystallization kinetics of thermoplastic polymer sheets is developed using a tensile-strength instrument. The isometric crystallization method allows investigating the shrinkage force on time of crystallization of stretched samples of thermoplastic polymer sheets or immobilization medical devices. The dependence of the shrinkage force on time is described by Avrami equation and the kinetics parameters of isometric crystallization are calculated. This revised version was published online in July 2006 with corrections to the Cover Date.     

电极法测定废水中氨氮

介绍了采用电极法测定废水中氨氮时,以吹气法代替蒸馏法对废水水样进行预处理,简化了水样预处理的程序,样品中氨氮的释出率可达90%,加标回收率在60%-98.8%之间。对两种废水样各分析8次,得出其RSD值均小于5%。按3倍标准偏差计算方法的检出限为0.008 mg.L-1。定量测定的最高值为350 mg.L-1。     

笼形聚氨肟树脂的研究：碱处理对吸附性能的影响

研究碱处理的笼形聚氨肟树脂（ＢＣＡＯ）对二价金属离子的吸附行为。吸附结果若生成２：１配的，得Ｍｇ＾２＋，Ｃａ＾２＋，Ｂａ＾２＋，Ｍｎ＾２＋，Ｃｏ＾２＋，Ｎｉ＾２＋，Ｚｎ＾２＋，Ｃｄ＾２＋，Ｐｂ＾２＋，Ｃｕ＾２＋离子的吸附效率分别是２７．１、２９．２、３０．４、２９．０、２７．１、３０．８、４５．０、３９．８、６０．３、６２．１％，Ｈｇ＾２＋离子的吸附效率高达１０５％，表明在吸附过程中同时生成２：１     

Chemometric data analysis of pollutants in wastewater—a case study

In this study, chemometric techniques such as cluster analysis (CA), discriminant analysis (DA), principal component analysis (PCA) and partial least squares (PLS) were used to analyse the wastewater dataset to identify the factors which affect the composition of sewage of domestic origin, spatial and temporal variations, similarity/dissimilarity among the wastewater characteristics of cis- and trans-drains and discriminating variables. Samples collected from 24 wastewater drains in Lucknow city and from three sites on Gomti river in the month of January/February, May, August and November during the period of 5 years (1994-1999) were characterized for 32 parameters. The multivariate techniques successfully described the similarities/dissimilarities among the sewage drains on the basis of their wastewater characteristics and sources signifying the effect of routine domestic/commercial activities in respective drainage areas. Spatial and seasonal variations in wastewater composition were also determined successfully. CA generated six groups of drains on the basis of similar wastewater characteristic. PCA provided information on seasonal influence and compositional differences in sewage generated by domestic and industrial waste dominated drains and showed that drains influenced by mixed industrial effluents have high organic pollution load. DA rendered six variables (TDS, alkalinity, F, TKN, Cd and Cr) discriminating between cis- and trans-drains. PLS-DA showed dominance of Cd, Cr, NO₃, PO₄ and F in cis-drains wastewater. The results suggest that biological-process based STPs could treat wastewater both from the cis- as well as trans-drains, however, prior removal of toxic metals will be required from the cis-drains sewage. Further, seasonal variations in wastewater composition and pollution load could be the guiding factor for determining the STPs design parameters. The information generated would be useful in selection of process type and in designing of the proposed sewage treatment plants (STPs) for safe disposal of wastewater.     

Influence of drawing and heat treatment on surface free energies of polyethylene terephthalate fibers

The surface free energies of polyethylene terepthalate fibers with different draw ratios were experimentally determined by contact angle measurements inn-alkane/water systems. The dispersive component of the surface free energy increased with increasing draw ratio, whereas the nondispersive one remained almost constant. After heat treatment, the dispersive surface free energy increased, but was reduced above 140°C. The nondispersive component increased by heat treatment at 190°C. The increases in the density and birefringence of the fibres due to the drawing and heat treatment suggested that the increase in the dispersive surface free energy was caused by the increase in the atomic density at the fiber surface due to drawing and heat treatment. ESCA results indicated that the increment in the nondispersive surface free energy due to heat treatment was caused by the addition of functional groups to the fiber surface due to heat treatment.     

A review of heat treatment on polyacrylonitrile fiber

Developing carbon fiber from polyacrylonitrile (PAN) based fiber is generally subjected to three processes namely stabilization, carbonization, and graphitization under controlled conditions. The PAN fiber is first stretched and simultaneously oxidized in a temperature range of 200-300 °C. This treatment converts thermoplastic PAN to a non-plastic cyclic or a ladder compound. After oxidation, the fibers are carbonized at about 1000 °C in inert atmosphere which is usually nitrogen. Then, in order to improve the ordering and orientation of the crystallites in the direction of the fiber axis, the fiber must be heated at about 1500-3000 °C until the polymer contains 92-100%. High temperature process generally leads to higher modulus fibers which expel impurities in the chain as volatile by-products. During heating treatment, the fiber shrinks in diameter, builds the structure into a large structure and upgrades the strength by removing the initial nitrogen content of PAN precursor and the timing of nitrogen. With better-controlled condition, the strength of the fiber can achieve up to 400 GPa after this pyrolysis process.     

Chemical modification of polymer surfaces: a review

The main approaches that have been taken to chemically modify polymer surfaces are introduced and reviewed. These are wet chemical oxidation, plasma treatment, classical organic chemistry, and attachment of polymer chains. The extent to which each of these approaches can produce the specific modifications desired is discussed, and any unwanted effects that commonly occur are cited. Finally, the need for using several methods of surface analysis in concert to obtain adequate surface characterization is described.     

The efficacy and progress in using radiation as a quarantine treatment of tropical fruits—a case study in Hawaii

Most tropical fruits for export must be treated with an approved quarantine treatment. Three and a half decades of research have demonstrated the efficacy of irradiation as a quarantine treatment in terms of efficiency, effectiveness, and product quality retention. The USFDA and the USDA-APHIS approved irradiation to disinfest fresh foods/fresh papayas in 1986 and 1989, respectively. In early 1995, the Hawaii Department of Agriculture was granted a special permit from USDA-APHIS allowing untreated Hawaiian fruits to be irradiated on the US mainland. The objectives were to gain experience in commercial irradiation as a quarantine treatment and to gather data on shipping and handling procedures, and on product quality. In April 1995, the first shipment of Hawaiian fruit was irradiated at a minimum quarantine dose of 0.25 kGy in an Isomedix plant near Chicago, and then distributed to supermarkets in Illinois and Ohio. Continuous shipments, irradiation, and marketing of various tropical fruits in the US have shown commercial efficacy, quality retention, and excellent consumer acceptance. A commercial e-beam/converted X-ray facility was installed by Titan Corp. on the Island of Hawaii and was operational by late July 2000. Hawaii has become the first place in the world to use irradiation as a quarantine treatment of fruits.     

Localization of Iα and Iβ phases in algal cellulose revealed by acid treatments

Highly crystalline I-rich type Cladophora cellulose, which had been kept in never-dried condition, was treated in 60wt% sulfuric acid at 100°C, for 1–48h. The cellulose microcrystals thus obtained were analysed by X-ray diffractometry, FT-IR, and transmission electron microscopy. The I component was found to be more degraded than the I component. The cellulose I/I ratios of the samples acid-treated for 0, 24, and 48 h were about 8:2, 6:4, and 4:6, respectively. After the acid treatment, the microcrystals became narrower in width, and very sharp at their ends. These results indicate that the I phase is mostly located at the surface of the microcrystals, which is morphologically more susceptible to the acid treatment.