Novel blood-compatible waterborne polyurethane using chitosan as an extender

A series of novel block polymers of polyurethane (PU) and chitosan have been prepared in two steps. The first step is the preparation of PU prepolymer, obtained from polytetramethylene oxide glycol (PTMO, M_n = 1000), isophrone diisocyanate (IPDI), and 2,2′-dimethylol propionic acid (DMPA), followed by ionizing PU prepolymer with triethylamine (TEA). The second step involves PU chain-extended by water-soluble chitosan of low molecular weight (M_n = 5000) by self-emulsion polymerization method. The sizes of the latex particles, morphology, and copolymer architecture have been characterized by dynamic light scattering (DLS), general tensile test, infrared spectroscopy (IR), surface contact angle measurement, and transmission electron microscopy (TEM). Furthermore, it shows that the addition of chitosan remarkably increases anticoagulative property of PU elastomers confirmed by the recalcification time. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A disposable sensor based on immobilization of acetylcholinesterase to multiwall carbon nanotube modified screen-printed electrode for determination of carbaryl

A simple method has been devised for immobilization of acetylcholinesterase (AChE) covalent bonding to a multiwall carbon nanotube (MWNT)-cross-linked cellulose acetate composite on a screen-printed carbon electrode (SPCE) and a sensitive and disposable amperometric sensor for rapid determination of carbaryl pesticide is proposed. The immobilized enzyme was preserved on this film because of the excellent biocompatibility and non-toxicity of cellulose acetate. Based on the inherent conductive properties of the MWNT, the immobilized AChE had greater affinity for ATCl and excellent catalytic effect in the hydrolysis of ATCl. MWNT improved the interface enzymatic hydrolysis reaction and increased the amperometric response of the sensor. Under optimum conditions, the inhibition of carbaryl on AChE increased linearly with the increasing concentration of carbaryl in two ranges, from 0.01 to 0.5 μg mL⁻¹ and from 2 to 20 μg mL⁻¹, with the correlation coefficients of 0.9985 and 0.9977, respectively. The detection limit was 0.004 μg mL⁻¹ taken as the concentration equivalent to 10% decrease in signal. The sensor showed acceptable stability, accuracy and could be fabricated in batches, thus it is economic and portable. This type of disposable enzyme-based amperometric sensor has extensive application potential in environmental monitoring of pesticides.     

一个通用代理计费系统开发框架的设计与实现

用户在不同的网络环境中选择不同的代理软件实现上网和用户管理，这些代理软件既有共性又各具特色，为减少开发不同代理计费软件的工作量，提高开发效率，加快开发周期，提出利用软件重用的思想，将代理软件的差异集中到少数几个类的实现上，设计并实现一个通用代理计费系统开发框架，基于此框架利用相对简单的步骤开发了基于SQUID的代理计费系统，验证了框架的实用性和可行性，达到了设计目标。     

基于多孔硅及MEMS技术的微型质子交换膜燃料电池

分析了研究和发展微型质子交换膜燃料电池(μPEMFC)的重要意义和应用前景,介绍了基于多孔硅及MEMS技术的μPEMFC最新研究动态,讨论了μPEMFC的结构设计、加工过程及性能,提出了μPEMFC仍存在的问题及其技术发展对策。     

Are weaning foods causing impaired iron and zinc status in 1-year-old Swedish infants? A cohort study

Retrobulbar hematoma is a rare complication of blunt periorbital trauma with the potential disastrous consequence of visual impairment and blindness. The preoperative assessment, diagnostic symptoms and signs, as well as the treatment of this condition are reviewed. The patients presented as well as a review of the literature confirm that although retrobulbar hematoma is a rare complication of blunt periorbital trauma, irreversible visual sequelae can be prevented by prompt diagnosis and immediate surgical and pharmacological therapy.     

Novel polymeric aromatic lithium sulfonylimides as salts for polymer electrolytes

Three new polymeric aromatic lithium sulfonylimides were used as salts in high molecular weight poly(ethylene oxide) (PEO) electrolytes. Their conductivity and electrochemical stability behaviors were investigated. The electrolytes with lithium poly[4,4′‐(hexafluoroisopropylidene)diphenoxy]sulfonylimide (LiPHFIPSI) showed a better conductive performance compared with the other two lithium salts. The best conductivity was obtained for PEO/LiPHFIPSI EO/Li = 16 (1.90 × 10^?4 S/cm at 60°C). Thermal analysis indicated that the salts effectively decreased the crystallinity of PEO. Moreover, the electrolytes also had good electrochemical stability and their oxidative potential was to 5.5 V versus Li/Li⁺. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1802–1805, 2002     

In vitro kinetics of two human CYP1A1 variant enzymes suggested to be associated with interindividual differences in cancer susceptibility

A genetic polymorphism (A4889-->G) in the human CYP1A1 gene which creates an Ile462-->Val amino acid substitution has been suggested to cause altered enzymatic properties of CYP1A1. Since several epidemiological studies have shown an association between the CYP1A1-Val allele and lung cancer, we considered it of importance to evaluate the in vitro kinetic properties of the two CYP1A1 variants after expression of each cDNA in yeast. No differences were found in K(m) or Vmax for CYP1A1 dependent O-dealkylation of ethoxyresorufin and 3-hydroxylation of benzo(a)pyrene between the two variants. The data indicate that the Ile/Val polymorphism in human CYP1A1 is not functionally important.