Glyoxal Ozonation Process in Aqueous Solution

The process of ozonation of glyoxal in aqueous solution has been studied by following its chemical and kinetic evolution. Results show that the oxidative process leads to formation of carboxylic functions and carbon dioxide according to a constant selectivity ratio at varying conversion degree.. Comparison between the oxygen amounts of reaction products and the corresponding ozone consumptions reveals that molecular oxygen takes part in the reaction process. System behavior is explained on the basis of radical reaction mechanism.     

甲基丙烯酸甲酯和苯乙烯在离子液体中的自由基聚合

甲基丙烯酸甲酯和苯乙烯经4,4’-偶氮-双(4-氰基戊酸)引发,分别在离子液体([C4mim][PF6])和苯中进行了自由基聚合反应,比较了相同引发剂和单体投料比下,2种介质体系中的聚合速率、相对分子质量和分子量分布,得出2种单体在[C4mim][PF6]中的聚合速率、相对分子质量明显高于苯中的产物,且[C4mim][PF6]经多次重复使用,均能得到性能稳定的聚合产物。     

Fatty Acid Composition, Antioxidant Properties, and Antiproliferative Capacity of Selected Cold-Pressed Seed Flours

Cold-pressed seed flours from pumpkin, parsley, mullein, cardamom, and milk thistle were examined for total oil, fatty acid profile of the oil, total phenolic content (TPC), scavenging activities against peroxyl (ORAC), hydroxyl (HOSC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (RDSC) radicals, and antiproliferative capacity against HT-29 human colon cancer cells. The cold-pressed parsley seed flour contained a very high concentration of total oil—17.6 g/100 g flour—with primarily C18:1 fatty acid at 86.2 g/100 g fatty acids. All other flour oils had relatively high levels of saturated fats, ranging from 39.0 to 62.9 g/100 g fatty acids. The tested seed flours demonstrated significant TPC and free radical scavenging activities. Milk thistle seed flour had the highest TPC value of 25.2 mg gallic acid equivalent per g flour (GAE mg/g) followed by that of parsley seed flour at 8.1 GAE mg/g. Milk thistle seed-flour extract also had significantly higher antioxidant activities than all other extracts against all tested radicals. The milk thistle seed-flour extract had an ORAC value of 1131 μmol trolox equivalents (TE) per g flour (TE μmol/g), a HOSC value of 893 TE μmol/g, and an RDSC value of 61 TE μmol/g. Also, ORAC, HOSC, and TPC values were significantly correlated (P < 0.01) under the experimental conditions. The cold-pressed milk thistle seed flour inhibited the proliferation of HT-29 cancer cells in a dose-dependent manner. Results from this study suggest that these cold-pressed seed flours may serve as natural sources of antioxidants and may be used to improve human health.     

高交联度易加工硅烷交联管材专用料的研制

介绍了采用二步硅烷交联工艺制备高交联度易加工硅烷交联管材专用料的方法,讨论了基础树脂、助剂对专用料交联度和加工性能的影响;通过加入自由基捕捉剂的方法,抑制接枝反应过程中的碳-碳大分子交联,解决了二步法硅烷交联领域的技术瓶颈问题,使硅烷交联管材专用料既具有高的交联度又具有良好的加工性能.     

聚苯乙烯接枝聚氧乙烯两亲接枝共聚物合成的研究

本文采用大分子单体法合成了结构明确的两亲接枝共聚物—聚苯乙烯接枝聚氧乙烯 ( PS— g—PEO) ,通过 IR,NMR和 GPC系统表征了两亲接枝共聚物。通过定性和定量的表征研究 ,结果证明两亲接枝共聚物 PS— g— PEO具有预期的结构     

Scavenging and anti-fatigue activity of fermented defatted soybean peptides

Many bioactive peptides possess specific biological properties that make these potential ingredients of health-promoting foods. Increasing attention is being focused on physiologically active peptides derived from soybean proteins. In this study, soybean peptides were produced by fermentation of defatted soybean meal with Bacillus subtilis SHZ and purified by ultrafiltration and gel chromatogram. Free radical scavenging property and the effect on anti-fatigue of the peptides were evaluated in vitro and in vivo, respectively. Swimming endurance tests of mice were carried out after 20 days of soybean peptides administration (0, 100, 200, 400 mg/kg BW/day for control, low-dose, middle-dose and high-dose group, respectively). And the blood lactate and hepatic glycogen of mice were determined. Results showed that the purified peptides exhibited significant (P < 0.01) scavenging potencies on superoxide (62%) and hydroxyl (96%) at a concentration of 10 mg/ml. The average swimming time of the low-, middle- and high-dose group was increased by 20.91, 45.45 and 70% compared with that of control group, respectively. And administration with soybean peptides could significantly accelerate the clearance of blood lactate after mice swimming (P < 0.01). The hepatic glycogen storage of middle and high dose groups were obviously increased (P < 0.05). It suggested that the soybean peptides produced by fermentation could significantly alleviate physical fatigue of the mice.     

Radical-induced degradation mechanism of perfluorinated polymer electrolyte membrane

The degradation mechanism induced by radicals was investigated for Nafion^®-117 by solution analysis. Nafion^® was exposed independently to three kinds of radicals, OH, H and O₂⁻ which were produced separately by γ-irradiation. Based on the eluted elements, the scission site in the membrane was analyzed. The results showed that the scission site was classified into two and these locations were closely relating to oxidative and reductive reactions. The decreasing rate of proton conductivity was more significant under the influence of reductive radicals. The progression of the unzipping reaction of main chain was suggested to be initiated by the production of tertiary carbon radical by reductive radicals such as H and O₂⁻ with the aid of OH. The structural degradation such as collapse of cluster and the cluster decomposition as well as the performance degradation was found to be initiated by such reductive radicals.     

Inhibition of hemoglobin-mediated lipid oxidation in washed fish muscle by cranberry components

Fractions enriched in phenolic acids (Fraction 1), anthocyanins (Fraction 2), flavonols (Fractions 3 and 4) and proanthocyanidins (Fractions 5 and 6) were prepared from cranberry powder using Sephadex LH-20 chromatography. Fractions 2, 3, 4, and 5 had nearly equivalent reactivity in the total phenolate assay employed per mg dry weight of each fraction while Fractions 1 and 6 were less reactive. The ability of cranberry fractions to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals as well as their inhibitory effects on hemoglobin (Hb)-mediated lipid oxidation in washed cod muscle were assessed. Addition of cranberry fractions at a level of 74 μmol quercetin equivalents per kg of washed cod muscle extended the induction time of thiobarbituric acid reactive substances (TBARS) formation in the order: Fraction 1, Fraction 3, Fraction 4 > Fraction 2 > Fraction 5 > Fraction 6. This suggests that oligomeric polyphenols (e.g., proanthocyanidins) were least effective at inhibiting Hb-mediated lipid oxidation in washed cod muscle compared to the other classes of polyphenolics in cranberry. The ability of the different cranberry fractions to scavenge DPPH radicals did not reflect their relative ability to inhibit lipid oxidation in the washed cod muscle system. Quercetin was tentatively identified as a component in cranberry that was especially effective at inhibiting Hb-mediated lipid oxidation. The ability of flavonol and proanthocyanidin-enriched fractions to inhibit Hb-mediated lipid oxidation in spite of efforts to wash away the added polyphenolics prior to Hb addition indicated these classes of polyphenolics had binding affinities for insoluble components of washed cod muscle.     

Thirty years of Polynomial System Solving,and now?

In this introductory paper to the special issue, I describe first my personal view of the history of Polynomial System Solving during my career. Then I describe the main challenges which are now opened by the availability of efficient zero-dimensional solvers.     

Electroreduction of quinones under aprotic conditions

The electrochemical reduction of a series of quinones in DMF, acetonitrile and 1,2-dichloroethane under controlled potential conditions and in the presence/absence of benzene diazonium tetrafluoroborate, is presented. It provides an interesting entry to new hydroxycarboxamides, dioxins, cyanomethylated derivatives, and other useful compounds. The electrochemical behaviour of these systems and mechanistic proposals are given.