Inactivation of Gram-negative pathogens in refrigerated milk by reuterin in combination with nisin or the lactoperoxidase system

Inhibitory activity of reuterin (β-hydroxypropionaldehyde) combined with the antimicrobial peptide nisin or the lactoperoxidase system (LPOS) against food-borne Gram-negative pathogens in milk refrigerated at 4 and 8 °C was investigated. At 4 °C, reuterin (8 AU/ml) and LPOS were bactericidal against Salmonella enterica, Campylobacter jejuni, Aeromonas hydrophila and Yersinia enterocolitica, whereas the only effect recorded for nisin was a slight inhibition of Escherichia coli O157:H7. At 8 °C, reuterin was bactericidal against all the Gram-negative pathogens studied. Same results were attained with LPOS, except for its effect on Y. enterocolitica which was only bacteriostatic. The combination of reuterin with nisin did not enhance the antimicrobial effect of reuterin. A strong synergistic bactericidal activity of reuterin in combination with LPOS on E. coli O157:H7 and S. enterica was observed in milk at 4 °C, and against all the Gram-negative bacteria assayed in milk refrigerated at 8 °C. The application of both antimicrobials would be a useful means to inhibit pathogenic microorganisms, which may be present in milk due to postpasteurization contamination.     

二烷基二硫代氨基甲酸铁抗氧光敏剂配合体系及其应用研究

本文研究了二烷基二硫代氨基甲酸铁（ＦｅＤＲＣ），芳香酮和抗氧剂配合体系的组成，各组分的协同关系及其光降解聚乙烯的作用机理。结果表明，以ＦｅＤＲＣ配合体系为添加剂的聚乙烯地膜使用性能和光降解可控性良好，完全适全制造可控光降解聚乙烯的地膜。     

Structure-activity studies on aggregation pheromone components ofPityogenes chalcographus (Coleoptera: Scolytidae)

Syntheses of all four Stereoisomers (2S,5S; 2S,5R;2R,5R; and2R,5S) of chalcogran, a major component of the aggregation pheromone ofPityogenes chalcographus, and of all four isomers (2Z,4Z; 2Z,4E; 2E,4E; and 2E,4Z) of methyl 2,4-decadienoate (MD), the second major pheromone component, are briefly described. Attraction responses of walking beetles of both sexes were tested to mixtures of the synergistic pheromone components or analogs. These bioassays showed that theE,Z isomer of MD is the most active when tested with chalcogran. When tested with (E,Z)-MD, (2S,5R)-chalcogran was the most active stereoisomer, while 2R,5R and 2R,5S isomers had intermediate activities, and the 2S,5S isomer was inactive. There was no evidence that the relatively less active Stereoisomers of chalcogran inhibited or promoted attraction to (2S,5R)-chalcogran with (E,Z)-MD. Male beetles only produce the activeE,Z isomer of MD (inactive alone) and their hindguts contain the most active (2S,5R)- and least active (2S,5S)-chalcogran. A mixture of all MD isomers with racemic chalcogran was not significantly different in attractivity compared to (E,Z)-MD with racemic chalcogran, indicating no synergistic or inhibitory effects of the inactive isomers of MD.     

Effect of synergism between potassium and phosphorus on selective hydrodesulfurization performance of Co–Mo/Al2O3 FCC gasoline hydro-upgrading catalyst

A series of potassium and/or phosphorus modified Co–Mo/Al₂O₃ FCC gasoline hydro-upgrading catalysts were prepared and the influences of potassium and/or phosphorus on the morphology, acidity and catalytic performance of the resulting catalysts were studied in the present investigation. The results showed that, compared to the single potassium or phosphorus modified catalyst, the Co–Mo–K–P/Al₂O₃ catalyst in which the atomic ratio of potassium to phosphorus was 2.0 could better balance the hydrodesulfurization and olefin saturation activities due to the compromised dispersion and stacking of MoS₂ slabs on the support as well as the good acidity property, and thus present the excellent selectivity in hydrodesulfurization. The present investigation also demonstrates the superiority of adjusting the K/P atomic ratio in optimizing the structure of MoS₂ slabs and thus provides a novel method for developing highly selective hydrodesulfurization catalysts.     

Studies on the thermal stabilization enhancement of ABS; synergistic effect by triphenyl phosphate and epoxy resin mixtures

Triphenyl phosphate (TPP) and its analogs are known to be the most effective flame retardant for acrylonitrile-butadiene-styrene copolymer (ABS) among various phosphorus-based compounds. But, its evaporation temperature is quite lower than the processing temperature of ABS. Therefore, it is inevitable to avoid a considerable amount of TPP to evaporate during processing. In order to overcome this undesirable phenomena, we incorporated various epoxy resins to TPP as coflame retardants and a series of ABS/TPP/epoxy compounds were made from them and their flame retardancy were evaluated by measuring the limiting oxygen index (LOI) values. Our results showed that the incorporated epoxy is very effective in suppressing the evaporation of TPP from the compounds and the LOI value as high as 38 is obtained. It is also found that more the epoxide ring contents in epoxy resins, the higher the LOI value of the compounds. The reason for this finding was postulated to come from the interaction between phosphoric acid and carboxylic acid generated from epoxy during thermal degradation. And some direct evidences from FTIR experiments were presented even though they were not conclusive. Moreover, the LOI values of quaternary mixtures of ABS, tetra-2,6-dimethyl phenyl resorcinol diphosphate, TPP, and epoxy resins were evaluated and that the same synergism of epoxy incorporation on flame retardancy was also found for them.     

酸洗缓蚀协同机理研究与进展

概述了酸洗缓蚀协同的重要性。综述了国内外酸洗协同缓蚀剂的研究现状及协同作用的分类,根据研究应用的不同情况,列举了无机物与无机物之间、无机物与有机物之间、有机物与有机物之间的协同作用。并阐述了协同缓蚀机理及其发展趋势。     

水溶性复合磷酸酯添加剂抗磨性能研究

合成了水溶性复合磷酸酯,利用四球试验机考察了添加到水溶液中的抗磨性能,并优化了复合磷酸酯的配比,用扫描电子显微镜对钢球磨斑形貌和摩擦表面的元素组成进行了分析,四球结果表明,磷酸酯与硫化物硫脲,油性剂油酸三乙醇胺具有良好的协同抗磨效应,并存在一个最佳配比,电镜能谱分析表明,复合磷酸酯水溶液在摩擦表面与Ｆｅ发生化学反应,生成一种含磷富硫的化学反应膜,而且表面膜中硫,磷元素的含量比为２：１时极压抗磨性能     

阻燃HDPE中氢氧化铝的表面处理和阻燃增效

本文采用氢氧化铝（ＡＴＨ）改善高密度聚乙烯（ＨＤＰＥ）的阻燃性能,选用铝酸酯、钛酸酯等偶联剂,以及实验室自制的磷酸酯、Ｃ２２表面涂覆剂对ＡＴＨ进行表面处理,以增加ＡＴＨ与基体的相互作用和在基体中的分散效果。拉伸、冲击、燃烧（水平燃烧、氧指数）等性能的测试表明,经处理后的ＨＤＰＥ／ＡＴＨ填充材料的综合性能较好,尤其是韧性有较大提高,实验室自制的磷酸酯和Ｃ２２表面处理剂表现出较好的效果。添加阻燃增效剂的研究显示,加入红磷、硼酸锌等阻燃增效剂可显著提高ＨＤＰＥ／ＡＴＨ体系的阻燃性能。热失重分析结果表明,经偶联剂处理后,材料的耐热性得到提高,ＡＴＨ的脱水温度可由２２０℃提高至２７０～２８０℃。     

Constructing heterostructured CoSe2/Ni3Se4@N-doped carbon nanosheets/ketjen black carbon as a robust oxygen evolution electrocatalyst

We design and construct a novel heterostructured CoSe₂/Ni₃Se₄@N-doped carbon nanosheets/Ketjen black carbon (denoted as CoSe₂/Ni₃Se₄@NC/KB) via the combination of pyrolysis and hydrothermal method. As a result of the exceptional synergism between CoSe₂ and Ni₃Se₄ as well as high conductivity of carbon materials, the obtained CoSe₂/Ni₃Se₄@NC/KB drives an OER current density of 10 mA cm⁻² by an overpotential of 260 mV and displays a low Tafel slope of 68 mV dec⁻¹, outmanoeuvring commercial RuO₂ and IrO₂, control groups (i.e. Ni₃Se₄@NC/KB, CoSe₂@NC/KB, and CoSe₂/Ni₃Se₄@NC), as well as most hybrids of selenides and carbon materials reported recently.     

结核分支杆菌对抗痨药物组合依赖的初步调查

目的调查结核分支杆菌对抗痨多药组合的依赖情况。方法用双向匡氏琼脂培养基对184例结核杆菌阳性菌株进行多药组合HR、HRS、HRE依赖性实验。结果HR、HRS、HRE组合的依赖率分别为13．04％（24／184）,9．78％（18／1841,7．07％（13／184）。对HR组合依赖的24株菌株中,依赖R的占75％（17／24）,依赖H的占50％（12／24）,依赖H和R的占29．17％（7／24）,不依赖H和R的占4．17％（1／24）;对HRS组合依赖的18株菌中,依赖R的占94．44％（17／18）,依赖H的占44．44％（8／18）,依赖S的占38．89％（7／18）,同时依赖H、R、s的占16．67％（3／18）,均不依赖的占5．56％（1／18）,对HRE组合依赖的13株菌中,依赖R的占92．31％（12／13）,依赖H的占46．15％（6／13）,依赖E的占76．92％（10／13）,三者同时依赖的占30．77％（4／13）,三者均不依赖的未见。结论结核分支杆菌对多药组合HR、HRS、HRE具有不同程度的依赖现象,对三种药物组合依赖的菌株对R的依赖率最高。