A new anti-adhesion film synthesized from polygalacturonic acid with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide crosslinker.

The most commonly used anti-adhesion device for separation and isolation of wounded tissues after surgery is the polymeric film. In this study, a new anti-adhesion membrane based on polygalacturonic acid (PGA) has been synthesized, and its biocompatibility and anti-adhesion capabilities evaluated. The PGA film was reacted with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) to obtain a cross-linked PGA film with an 86% gel content and a 47% water content when immersed in aqueous solution. This PGA-EDC film did not show any evidence of cytotoxic effects since it did not induce any significant increase in cytoplasmic LDH release from the L929 cells in contact with it. When implanted into rats, the PGA-EDC film exhibited a most promising anti-adhesion potential with only 1 out of 21 rats operated not forming any tissue adhesion. This anti-adhesion potency is significantly higher than that found for Seprafilm and untreated rats where 11 out of 21 and 18 out of 21 operated rats, respectively, formed tissue adhesions. The implanted PGA-EDC film did not elicit any acute inflammatory reaction based on the results of histological examination and peritoneal fluid leukocytes analysis. The newly developed PGA-EDC film thus has a great potential for future use in clinical applications.

[Concentrations of PCDD/Fs in the atmosphere of Chongqing City and its seasonal variation].

As a comprehensive monitoring survey on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in Chongqing, 20 ambient air samples taken from 5 locations in four seasons were studied. The PCDD/F TEQ concentrations varied from 0.017 pg x m(-3) to 0.21 pg x m(-3). The average value was (0.094 +/- 0.054) pg x m(-3). The PCDD/F concentrations varied by locations and seasons, and the orders were: urban area > suburban area > background area, and Winter > Spring > Autumn > Summer. The concentrations of PCDD/Fs were 2.2-4.6 times higher in the winter than during the summer. The PCA results indicated that PCDD/F homologue pattern varied by seasons. The PCDD/F homologue pattern in particle dominated in winter and spring, and the pattern in gas dominated in summer and autumn. The mass concentration of PCDD/F congener was significantly positively correlated with that of SO2, NO2, PM10 and TSP, and insignificantly negatively correlated with that of O3, respectively. The results showed that spatial distribution and seasonal variation of atmospheric PCDD/Fs in Chongqing was consistent with that of these conventional indicators, and the PCDD/Fs pollution was closely related with the emission sources of SO2, NO2, PM10 and TSP.

[Atmospheric emission of PCDD/Fs from secondary aluminum metallurgy industry in the southwest area, China].

Five secondary aluminum metallurgy enterprises in the southwest area of China were measured for emissions of PCDD/Fs. The results indicated that the emission levels of PCDD/Fs (as TEQ) were 0.015-0.16 ng x m(-3), and the average was 0.093 ng x m(-3) from secondary aluminum metallurgy enterprises. Emission factors of PCDD/Fs (as TEQ) from the five secondary aluminum metallurgy enterprises varied between 0.041 and 4.68 microg x t(-1) aluminum, and the average was 2.01 microg x t(-1) aluminum; among them, PCDD/Fs emission factors from the crucible smelting furnace was the highest. Congener distribution of PCDD/F in stack gas from the five secondary aluminum metallurgies was very different from each other. Moreover, the R(PCDF/PCDD) was the lowest in the enterprise which was installed only with bag filters; the R(PCDF/PCDD) were 3.8-12.6 (the average, 7.7) in the others which were installed with water scrubbers. The results above indicated that the mechanism of PCDD/Fs formation was related to the types of exhaust gas treatment device. The results of this study can provide technical support for the formulation of PCDD/Fs emission standards and the best available techniques in the secondary aluminum metallurgy industry.

[Atmospheric emission of PCDD/Fs from modern dry processing cement kilns with preheating in the southwest area, China].

Six cement kilns were measured for emissions of PCDD/Fs in the Southwest Area, China. The results indicated that the emission levels of PCDD/Fs were 0.0029-0.0062 ng-m(-3) (Average, 0.0043 ng X m(-3)) from cement kilns which did not burn solid waste, and 0.028 ng X m(-3) from co-processing sewage sludge in cement kiln. The levels of PCDD/Fs emissions from cement manufacturing in the Southwest Area were significantly below the national emissions standard (0.1 ng x m(-3)). Emission factors of PCDD/Fs from the six cement kilns varied between 0.0089 and 0.084 microg x t(-1) cement, which were near or below the lowest emission factor reported by UNEP in 2005. Moreover, the emission factor of PCDD/Fs from co-processing sewage sludge in cement kiln was 7.6 times of the average factors from the other five cement kilns. Moreover,congener distribution of PCDD/F in stack gas from the two types of cement kilns was very different. The results showed that modern dry process cement kilns with preheating have lower emissions of PCDD/Fs. This suggested that the product of co-processing solid waste in cement kilns should be largely enhanced in China in future.

Effect of microtopographic structures of silk fibroin on endothelial cell behavior.

Stent implantation has become the preferred revascularization treatment for occlusive blood vessel disease; however, there are occasionally complications resulting in re-narrowing of the treated artery. One approach to overcoming this problem is to establish a confluent monolayer of endothelial cells (ECs) on the stent, and a coating would facilitate the attachment of ECs. Silk fibroin was reported to be used as an ideal coating applied to stent for the culture of human ECs. The aim of the present study is to gain more insight into the influence of the internal microtopographical structure of silk fibroin on cell behavior, such as attachment and growth, and to further investigate its molecular mechanism using human umbilical vein ECs (HUVECs). Our results evaluated the effect of different microtopographical structures on cell behavior. In addition, we analyzed the cell cycle and investigated relevant molecules involved. The results indicated that the microtopographic structure of silk fibroin was associated with EC morphology, attachment and proliferation.