公益一类食品检验检测机构建设

食品安全问题已成为国家治理中的重大问题和关注焦点,而食品检验检测是食品安全监管的重要技术支撑手段,加强食品检验检测机构建设对提高食品安全监管水平具有十分重要的意义。本文结合我国检验检测行业的现状,从公益一类检测机构的非盈利属性出发,阐述了公益一类食品检验检测机构建设对食品安全监管的必要性,并进一步对公益一类检验检测机构存在的问题进行了深入分析,最后就加强公益一类食品检验检测机构建设,完善食品安全监管技术支撑体系提出对策建议。     

新型丝网制版感光材料

感光材料是化学法制作丝网模版的重要制版材料,主要分两大类,一类是乳剂型感光胶,将其涂布于丝网上可形成版膜;一类是直接感光膜片,直接贴附于丝网上,即可形成版膜.     

导电高分子材料探究

导电高分子复合材料是一类具有重要理论研究价值和广阔应用前景的新型功能材料,导电高分子材料具有高电导率、半导体特性、电容性、电化学活性,同时还具有一系列光学性能等,具有与一般聚合物不同的特性。因此,导电高分子复合材料是一类具有重要理论研究价值和广阔应用前景的新型功能材料。     

宏观经济政策对木工机械市场的影响

木材加工机械（以下称木工机械）是林业机械的重要组成部分,是指将木材加工成为木制品的一类机械。木工机械细分门类比较多,通常包括制材机械、干燥设备、家具机械、地板机械、门窗机械、其他木制品机械等。由于木制品与人们日常生活息息相关,因此支撑木制品加工的木工机械作为一类专用机械具有十分重要且不可替代的作用。     

浅谈天然酵母面包的现状及发展趋势

面包是利用酵母的生物发酵作用,经烘烤制作成的一类面点制品,是西式面点中很重要的一类产品。文章对天然酵母面包的概述、现状、天然酵母面包的发展未来趋势做粗浅的研究,以期在大众生活中更好的推广天然酵母面包。     

生物多糖类物质对人体的作用

生物多糖是一类重要的保健食品功能因子，叙述对人体的各种保健作用。     

乳酸菌胞外多糖生理功能及合成途径的研究进展

乳酸菌(Lactic acid bacteria,LAB)是一类重要的益生微生物,同时也是一类重要的工业发酵菌,在食品发酵生产上应用广泛,它的代谢产物也受到极大关注。本文总结了乳酸菌代谢合成的胞外多糖(Exopolysaccharide,EPS)的主要生理生化功能以及胞外多糖合成的四个主要过程,以期为乳酸菌EPS的应用、产量提高及结构改造提供指导。     

普洱茶多酚与茶褐素研究进展

普洱茶是一类具有多种保健功能的后发酵茶,其中多酚和茶褐素都是重要的功能成分。普洱茶茶褐素是一类结构十分复杂的多酚氧化产物,属于天然色素。本文综述了普洱茶多酚和茶褐素的最新研究进展,包括提取分离、功能研究、茶褐素的结构探讨、变化特点、生物活性等。     

醋酸乙烯酯共聚物乳液在造纸中的应用

醋酸乙烯酯共聚物乳液是一类重要的化工原料,在造纸中得到较广泛应用。综述了醋酸乙烯酯共聚物乳液在造纸工业的应用进展。     

醋酸乙烯酯共聚物乳液在造纸中的应用

醋酸乙烯酯共聚物乳液是一类重要的化工原料,在造纸中得到较广泛应用。该文综述了醋酸乙烯酯共聚物乳液在造纸工业应用进展。     

蜜环菌水溶性多糖的抗氧化活性研究

目的:通过蜜环菌水溶性多糖对·OH、O2-·和DPPH·三种自由基清除作用,评价其抗氧化性能,为蜜环菌药物制剂的活性研究及其产品的质量检测标准提供重要参考。方法:经热水浸提、除蛋白等步骤分离纯化到水溶性多糖,以抗坏血酸和TBHQ为对照,采用分光光度法评定其抗氧化特性。结果:蜜环菌水溶性多糖对三种自由基均有不同程度的清除活性,对三种自由基的清除能力是DPPH·>·OH>O2-·,当清除率达到90%以上时,清除DPPH·、·OH和O2-·的所需的多糖浓度分别为1.0、5.0、6.0mg·mL-1,蜜环菌多糖的清除能力显著。结论:蜜环菌水溶性多糖在体外具有较明显的抗氧化活性,在实验浓度范围内,抗氧化效果与浓度呈显著的线性相关。作为一种重要的天然活性物质,蜜环菌多糖的抗氧化活性和抗衰老作用将具有较高的应用价值。     

果蔬中多酚类化合物双向调控Nrf2/Keap1信号通路的研究进展

果蔬中含有丰富的多酚类化合物,其含有的酚羟基中邻位酚羟基极易被氧化,有较强捕捉活性氧等自由 基的能力,因此能够清除自由基和淬灭活性氧。Nrf2（NF-E2-related factor 2）信号通路是增强机体抗氧化功能最 重要的保护性信号途径,在细胞抵御氧化应激机制中有着重要的地位,是抗氧化研究领域的热点。本文通过阐述 Nrf2/Keap1（Kelch-like ECH-associated protein 1）信号通路及其调节方式,讨论Nrf2在肿瘤化学预防和促进癌症发 生中的双重作用,重点介绍和归纳了果蔬中几种典型的多酚类物质对Nrf2/Keap1信号通路双向调控作用的分子机 制,以期为利用果蔬多酚开发健康绿色食品和药品提供一定的理论依据。     

ANTIOXIDANT AND CALMODULIN-INHIBITORY ACTIVITIES OF PHENOLIC COMPONENTS IN FRUIT WINES AND ITS BIOTECHNOLOGICAL IMPLICATIONS

Fruits are rich sources of anthocyanins, flavonoids and phenols that are important nutraceutical components. Processed products of various fruits such as wines and juices, also contain these nutraceuticals, and have been proposed to be the primary components that provide health-beneficiary effects to the cardiovascular system. In the present study, we have evaluated the antioxidant and calmodulin-inhibitory effects of three fruit wines and a red grape wine to provide a comparison in their nutraceutical properties. Using in vitro systems that generate superoxide radicals and hydroxyl radicals, all the wines and their partially purified phenolic extracts were demonstrated to possess strong superoxide and hydroxyl radical scavenging properties. On the basis of specific phenolic content, the summer cherry, blackberry and blueberry wines were 30-40% more efficient in superoxide radical scavenging than red grape wine. Similarly, blueberry wine demonstrated considerably high hydroxyl radical scavenging efficiency than the other wines. The flavonoid aglycones such as catechin and naringenin, were as efficient or more in scavenging superoxide radicals, as ascorbate. As well, these compounds also scavenged hydroxyl radicals, as or more effectively than melatonin, a known hydroxyl radical scavenger. All the wines had components that inhibited calcium and calmodulin-promoted phosphodiesterase activity, indicating their potential to interfere with the calcium second messenger function. Blueberry, blackberry and red wine components were more effective in the inhibition of calmodulin-promoted phosphodiesterase than those from summer cherry wine. Active oxygen scavenging or calmodulin-inhibitory properties appear to be associated with a variety of wine components that may provide synergistic action than any single components in them. This study paves way for the potential use of fermentation biotechnology to optimize the enzymatic release and levels of nutritionally important phenolic components in fruit wines.     

含氧类自由基与过氧化氢脱木素

介绍了纸浆过氧化氢漂白中的含氧类自由基,如羟基自由基、过氧阴离子自由基和氢过氧自由基,以及自由基与过氧化氢脱木素及漂白的关系.讨论了这些自由基的产生、自由基与木素反应的特点、羟基自由基的脱木素选择性以及pH值对其影响,提出通过控制漂白体系中的压力、温度和过氧化氢用量来调控过氧化氢的传递、自由基的产生以及自由基浓度,合理地利用自由基反应来提高过氧化氢的脱木素能力,改善漂白效果.     

ANTIOXIDANT AND CALMODULIN-INHIBITORY ACTIVITIES OF PHENOLIC COMPONENTS IN FRUIT WINES AND ITS BIOTECHNOLOGICAL IMPLICATIONS

Fruits are rich sources of anthocyanins, flavonoids and phenols that are important nutraceutical components. Processed products of various fruits such as wines and juices, also contain these nutraceuticals, and have been proposed to be the primary components that provide health-beneficiary effects to the cardiovascular system. In the present study, we have evaluated the antioxidant and calmodulin-inhibitory effects of three fruit wines and a red grape wine to provide a comparison in their nutraceutical properties. Using in vitro systems that generate superoxide radicals and hydroxyl radicals, all the wines and their partially purified phenolic extracts were demonstrated to possess strong superoxide and hydroxyl radical scavenging properties. On the basis of specific phenolic content, the summer cherry, blackberry and blueberry wines were 30–40% more efficient in superoxide radical scavenging than red grape wine. Similarly, blueberry wine demonstrated considerably high hydroxyl radical scavenging efficiency than the other wines. The flavonoid aglycones such as catechin and naringenin, were as efficient or more in scavenging superoxide radicals, as ascorbate. As well, these compounds also scavenged hydroxyl radicals, as or more effectively than melatonin, a known hydroxyl radical scavenger. All the wines had components that inhibited calcium and calmodulin-promoted phosphodiesterase activity, indicating their potential to interfere with the calcium second messenger function. Blueberry, blackberry and red wine components were more effective in the inhibition of calmodulin-promoted phosphodiesterase than those from summer cherry wine. Active oxygen scavenging or calmodulin-inhibitory properties appear to be associated with a variety of wine components that may provide synergistic action than any single components in them. This study paves way for the potential use of fermentation biotechnology to optimize the enzymatic release and levels of nutritionally important phenolic components in fruit wines.     

Photoinduced oxidation of antimony(III) in the presence of humic acid

Interactions of antimony with natural organic matter (NOM) are important for the fate of Sb in aquatic systems. The kinetics of the photosensitized oxidation of Sb(III) to Sb(V) in the presence of Suwannee River Humic Acid (SRHA) was investigated using UV-A and visible light (medium-pressure mercury lamp). At a concentration of 5 mg L(-1) dissolved organic carbon (DOC) the light-induced reaction was 9000 times faster (rate coefficient k(exp) = 7.0 +/- 0.05 x 10(-4) s(-1)) than the dark reaction and followed pseudo-first-order kinetics. Rates increased linearly with the concentration of DOC. Between pH 4 and 8 rates increased by a factor of 5. Further results and kinetic considerations indicate that singlet oxygen, hydroxyl radicals, hydrogen peroxide, and hydroperoxyl radicals/superoxide are not important photooxidants in this system, while other NOM-derived reactive species, in particular excited triplet states and/or phenoxyl radicals, seem to be relevant. The dependence of rate coefficients on Sb(III)/DOC ratio was consistent with a two binding site model including (i) a strong binding site at low concentration inducing fast oxidation, (ii) a weak binding site at high concentration inducing slower oxidation, and (iii) the even slower oxidation of Sb(OH)3. Photoirradiation of natural water samples spiked with Sb(III) showed that the oxidation rates could be well predicted based on DOC.     

超氧化物歧化酶在医药临床上的研究和应用

超氧化物歧化酶(SOD)是重要的消除体内自由基的金属酶,它的抗氧化功能不足或受损时可诱发或引起多种疾病。补充SOD制剂在临床有重要价值。本文对与人体相关的SOD在医药临床方面的研究和应用作一综述。     

Kinetic modeling of TiO2-catalyzed photodegradation of trace levels of microcystin-LR

A kinetic model has been developed to investigate the relative importance of major pathways for the photocatalytic degradation of trace levels of the cyanobacterial toxin microcystin-LR (MLR) in solutions containing a complex suite of dissolved organic matter and to test the sensitivity of MLR degradation to rate constants of the key processes. The kinetic model incorporates adsorption of the trace contaminant, other organics and oxygen on the particle surface, surface reactions between adsorbed radical and nonradical species, desorption of surface radical species, solution phase radical reactions, and radical termination pathways. Under conditions where the contaminant adsorbs strongly to semiconductor surface sites, rapid degradation is observed, and a primary degradation step appears to involve reaction between surface-located long-lived organic radicals (formed from hydroxyl radical scavenging by the bulk organic) and adsorbed trace contaminant. MLR degradation is relatively insensitive to changes in light intensity under these strongly adsorbing conditions but highly dependent under weakly adsorbing conditions and when solution phase degradation is important. While not verified independently, desorption of surface bound superoxide appears to lead to the production of organic peroxyl radicals through reaction of superoxide with the bulk organic. These solution phase organic peroxyl radicals are highly reactive and appear to be the primary source of trace contaminant degradation under conditions where the trace contaminant shows no observable adsorption and surface degradation is negligible. Under alkaline conditions, adsorption of carbonate onto the particle surface results in scavenging of surface hydroxyl radicals to form surface carbonate radicals that rapidly quench surface bound superoxide. This prevents organic peroxyl production, the primary agent of solution-phase trace contaminant degradation.     

Standard Gibbs free energies of reactions of ozone with free radicals in aqueous solution: quantum-chemical calculations

Free radicals are common intermediates in the chemistry of ozone in aqueous solution. Their reactions with ozone have been probed by calculating the standard Gibbs free energies of such reactions using density functional theory (Jaguar 7.6 program). O(2) reacts fast and irreversibly only with simple carbon-centered radicals. In contrast, ozone also reacts irreversibly with conjugated carbon-centered radicals such as bisallylic (hydroxycylohexadienyl) radicals, with conjugated carbon/oxygen-centered radicals such as phenoxyl radicals, and even with nitrogen- oxygen-, sulfur-, and halogen-centered radicals. In these reactions, further ozone-reactive radicals are generated. Chain reactions may destroy ozone without giving rise to products other than O(2). This may be of importance when ozonation is used in pollution control, and reactions of free radicals with ozone have to be taken into account in modeling such processes.     

Immunological properties of human decidual macrophages--a possible role in intrauterine immunity

Our aim was to investigate the contribution of decidual macrophages, which constitute an important immune component of the decidua in late gestation, to intrauterine defence mechanisms. Using flow cytometry we examined the ability of decidual macrophages, isolated from term decidua, to bind and phagocytose fluorescence-labelled bacterial and yeast bioparticles. We also assessed their ability to generate superoxide radicals and tumour necrosis factor-alpha following lipopolysaccharide challenge. Decidual macrophages bound bacterial and yeast particles in a dose-dependent manner, which subsequently led to phagocytosis. These macrophages also produced superoxide radicals and the pro-inflammatory cytokine TNF-alpha when challenged with bacterial lipopolysaccharides. These results suggest a role for decidual macrophages in pathogen recognition and clearance during pregnancy, and, therefore, they are likely to protect the fetus against intrauterine infections which might otherwise lead to preterm labour.