ClO2消毒涉及毒性问题的探讨

对二氧化氯 Cl O2 消毒无机副产物亚氯酸盐 Cl O2 - 和氯酸盐 Cl O3- 来源进行了分析 ,高浓度的 Cl O2 、Cl O2 - 和 Cl O3- 的毒性主要与血液系统有关 ,在相当于人饮用 Cl O2 、Cl O2 - 和 Cl O3- 混合溶液 1 60倍的动物血液常规检测中未发现异常 ,Ames试验显示试验浓度的 Cl O2 、Cl O2 - 和 Cl O3-水溶液不具有致突变作用 .     

Inhibition of Escherichia coli O157:H7, Listeria monocytogenes and Staphylococcus aureus on sliced roast beef by cetylpyridinium chloride and acidified sodium chlorite

The effects of 0.5% cetylpyridinium chloride (CPC), 0.12% acidified sodium chlorite (ASC) and a mix of equal volume of the two (0.25% CPC-0.06% ASC) on Escherichia coli O157:H7, Listeria monocytogenes and Staphylococcus aureus were evaluated on inoculated sliced roast beef. The antimicrobial agents were, respectively, sprayed on the beef surfaces and tray absorbent pads, and samples were stored at 4 degrees C for 10 days (d). At 0 d, L. monocytogenes and S. aureus were reduced to undetectable levels in 2 h after spraying with CPC. CPC-ASC treatment reduced E. coli O157:H7, L. monocytogenes and S. aureus by 4.07, 6.37 and 4.32 log cfu/cm2, respectively, at 0 d. ASC treatment reduced the population of E. coli O157:H7 by 6.09 log cfu/cm2 at 10 d. CPC treatment caused a slight discoloration and ASC-treated beef surfaces demonstrated the lowest redness and highest lightness. The grey colour and off-odour were significant in the ASC-treated beef samples, while CPC-treated samples demonstrated less off-odor and brown colour from 0 to 4 d. Based on our results, it appears that the application of CPC on sliced roast beef can extend the shelf-life of the product without impairing its quality.     

Dual effectiveness of sodium chlorite for enzymatic browning inhibition and microbial inactivation on fresh-cut apples

The dual effectiveness of sodium chlorite for browning inhibition and microbial inactivation on fresh-cut apples was investigated and compared to other anti-browning and antimicrobial agents. Results indicate that sodium chlorite significantly (P < 0.001) inhibited the browning reaction of fresh-cut Red Delicious apples stored at 5 °C for 14 days. This treatment also significantly reduced polyphenol oxidase activities. Treatments with acidified sodium chlorite, calcium chloride, or calcium ascorbate exhibited strong inhibition on apple browning during the early storage, these treatment effects diminished after 7 days in storage. Combining calcium chloride with sodium chlorite further significantly (P < 0.001) improved the firmness of apple slices, and browning inhibition during storage. Additionally, treatments with acidified sodium chlorite, sodium chlorite, or the combination of sodium chlorite and calcium chloride significantly (P < 0.001) reduced Escherichia coli populations on fresh-cut apples by 3.0, 3.6, and 3.9 log cfu g⁻¹ over the water control. The dual effectiveness of sodium chlorite to inhibit enzymatic browning and inactivate E. coli may allow this compound to achieve a prominent role in improving the quality and safety of products in the fresh-cut apple and other food industries.     

俄罗斯绿泥石玉的矿物学特征研究

采用折射仪、紫外荧光灯、X射线衍射分析以及扫描电子显微分析,对一种近来出现在市场上的玉石新品种、来自俄罗斯的绿泥石玉———“天使之玉(seraphinite)”———的宝石学特征、微观结构及其矿物学特征进行了研究。结果表明,该绿泥石玉呈深绿色、微透明—不透明集合体,具鳞片变晶结构,裂隙少,质地均匀,在紫外荧光灯下不发荧光,摩氏硬度为2.5,折射率为1.58,密度为2.60g/cm3。X射线衍射分析结果表明,该绿泥石玉的物相为绿泥石。扫描电子显微分析结果表明,绿泥石晶体发育良好,可见不同排列方向上的绿泥石晶体集合体呈交叉分布。能谱结果表明,该绿泥石晶体的化学组成w(MgO)为35.4%,w(Al2O3)为14.8%,w(Si O2)为32.6%,w(FeO)为4.2%,w(H2O)为13.0%。该绿泥石玉基本由斜绿泥石组成,斜绿泥石的晶体化学式为:Mg6(Fe0.7Mg3.8Al1.5)(Si6.2Al1.8)O20(OH)16;晶体呈定向排列,颗粒较大的片状晶体产生波状弯曲现象。这些结构特征是造成该绿泥石玉具有丝绢光泽的可能原因。     

自生CO2驱油技术体系及驱油效果研究

针对常规CO2驱存在气源、输送、腐蚀等问题,对自生CO2驱油技术进行了研究。给出了自生CO2驱油机理,在考虑反应速度、经济因素的基础上,筛选出自生CO2体系,对优选出的体系进行原油膨胀、降黏效果评价实验,并利用微观模型和物理模型研究了其驱油机理和效果。实验表明,自生CO2驱油技术在低温时应选用双液法体系,高温选用单液法体系;在一定温度压力条件下,该技术能够使模拟原油膨胀10%~32.5%,油越稠效果越好;可使原油黏度降低38.1%~57.2%;在水驱后能够提高填砂模型采收率6.4~15.5个百分点,双液法效果好于单液法。室内实验和先导性试验表明,自生CO2驱油具有良好的效果,是一种极具潜力的技术。     

绿泥石与土酸、氟硼酸反应实验研究

研究了美国标准矿物绿泥石与7种常用酸(5%HCl,5%HCl 0.5%HF,5%HCl 1.0%HF,0.5%HF,1%HF,8%HBF,5%HCl 7%HBF4)在60℃下的反应.发表了反应0.5、1.0、2.0、12.0 小时后7种反应液中可溶硅、可溶铝的浓度(mg/L)和绿泥石的溶蚀率数据.一般而言,可溶硅浓度在0.5小时,可溶铝浓度在2小时即达到最大值;可溶硅、可溶铝浓度在盐酸反应液中很低,在氟硼酸反应液中随反应时间延长而升高,在复合酸和氢氟酸反应液中在不同程度上出现下降或波动,表明有二次沉淀.绿泥石的12小时溶蚀率,在1/5和0.5/5土酸中最高(28.68%,22.50%),在5%盐酸和复合氟硼酸中次之(20.83%,17.75%),在氟硼酸(6.81%)和土酸(～2%)中很低.用能谱电镜检测,与1/5土酸、复合氟硼酸反应2小时后的绿泥石表面,Si的质量分数大幅增大,Al、Fe的质量分数大幅减小,新出现F,证实有硅酸盐和氟化物沉积.绿泥石与各种酸液反应12小时后.(001)和(002)晶面衍射峰形和峰位不变,与氟硼酸特别是复合氟硼酸反应后,两晶面衍射峰高度降低,在2θ=15.8°和18.2°处出现新衍射峰,表明有新矿物生成或发生了矿物转化.图1表3参3.