Comparison among the effectiveness of ozone,nisin and benzalkonium chloride for the elimination of planktonic cells and biofilms of Staphylococcus aureus CECT4459 on polypropylene

In search for alternative disinfection methods to prevent the development of bacterial resistances, the effectiveness of benzalkonium chloride (BAC), nisin and ozone against planktonic cells and biofilms of Staphylococcus aureus CECT 4459 was compared. Maximum effect of each compound was determined by comparing the times of exposure at which maximum mortality was reached. A dose–response study was carried out at such exposure times and LD₉₀ values (doses causing 90% of mortality) were determined. BAC and ozone were more effective against biofilms than against planktonic cells, presumably due to a higher accessibility of biofilm cells. Concerning the control of biofilms, BAC was highly effective, but the application of 250 IU/ml of nisin or 1 μg/g of ozonized water allowed to reach 99% inactivation in only 2 min. It is concluded that nisin and ozone could be good alternative disinfectants to prevent the development of bacterial resistances, but factors such as applicability, price and risk to employers and food should also be taken into account.     

Adherence kinetics, resistance to benzalkonium chloride and microscopic analysis of mixed biofilms formed by Listeria monocytogenes and Pseudomonas putida

Comparison between the resistance to BAC and the microscopic structure between mixed-species biofilms formed by different strains of Listeria monocytogenes and Pseudomonas putida CECT 845 under different scenarios and that obtained by the corresponding monospecies L. monocytogenes biofilm was carried out. The association of P. putida with L. monocytogenes quickens biofilm formation and increases significantly (p < 0.05) the BAC-resistance of the biofilm after 4 days of incubation at 25 °C respecting to that formed by monospecies biofilms. According with the adherence profiles of P. putida, two different patterns of association between both species (A and B) were identified, being type A pattern found in the mixed biofilms much more resistant to BAC. After 11 days of incubation, a destructuration of mixed biofilms occurred in all experimental assays, being in 2 out of 5 experimental cases (4032 and BAC-adapted 5873 on polypropylene) accompanied by a sharp decrease in the number of adhered cells. Microscopic analyses demonstrated that complex three-dimensional microscopic structure showed the highest resistance to BAC (4032-SS). Obtained results clearly highlight that to improve disinfection protocols for assuring food safety, it is necessary to mimick those bacterial association that occur in nature.     

Biofilm formation by Salmonella Typhimurium and Staphylococcus aureus on stainless steel under either mono- or dual-species multi-strain conditions and resistance of sessile communities to sub-lethal chemical disinfection

Intercellular interactions encountered within and between different bacterial species are believed to play key roles in both biofilm formation and antimicrobial resistance. In this study, Salmonella Typhimurium and Staphylococcus aureus (3 strains per species) were left to form biofilms on stainless steel coupons incubated at 20 °C for 144 h (i.e. 6 days), in periodically renewable growth medium, under either mono- or dual-species conditions. Subsequently, the developed sessile communities were exposed for 6 min to sub-lethal concentrations of: (i) benzalkonium chloride (BC, 50 ppm), (ii) sodium hypochlorite (NaClO, 10 ppm), or (iii) peroxyacetic acid (PAA, 10 ppm). The dominance of each strain in the mono- and dual-species biofilm communities, both before and after disinfection, was monitored by pulsed field gel electrophoresis (PFGE). Results revealed that dual-species conditions led to a significant (ca. 10-fold) reduction in the number of sessile cells for both species, compared to mono-species ones, with interspecies interactions however found to not exert any significant effect on the disinfection resistance of each species as a whole. However, PFGE analysis revealed that the different strains here employed behaved differently with regard to biofilm formation and disinfection resistance, with this effect to be also strongly dependent on the culture conditions (mono-/dual-species) and the disinfectant applied. Such results expand our knowledge on multi-species biofilms formed by foodborne pathogenic bacteria and could hopefully be helpful in our efforts to develop effective elimination strategies and thus improve food safety.     

空化水射流物理化学效应分析

空化水射流是射流流场某点压力降至饱和蒸汽压以下,伴随有气泡产生、长大和破灭过程的一种新型射流,空泡溃灭产生瞬间高温和高压现象,伴随有H^＋和OH^＋等强氧化物质的产生。利用高温、高压及微射流等物理效应,可以显著地提高射流清洗、除锈、破碎效果及改善金属表面性能的能力。通过机械剪切、热解、自由基氧化和超临界水氧化等化学效应,可以对毒性难降解有机物进行化学降解。空化水射流在石油、矿业及环保等领域具有广阔的应用前景。     

Effects of exposure to biocides on susceptibility to essential oils and chemical preservatives in bacteria from organic foods

A collection of 38 biocide-adapted strains with significant increases in their tolerance to biocides after step-wise exposure to these compounds were screened for sensitivity to essential oils and chemical preservatives. Several strains adapted to quaternary ammonium compounds (benzalkonium chloride, hexadecylpyridinium chloride or cetrimide) showed a generalized increase in the sensitivity to preservatives. Similar results were found among hexachlorophene- or chlorhexidine-adapted strains. Moreover, tolerance to hexadecylpyridinium chloride showed a very strong positive correlation with 4-hydroxybenzoic acid, thyme oil and sodium nitrite increased sensitivity, as well as a strong correlation with clove oil, potassium sorbate and potassium nitrate increased sensitivity. On the contrary, an increase in tolerance to preservatives was detected among triclosan-adapted strains. Results from this study suggest that exposure of bacteria from foods to biocides is not always associated with co-selection for other antimicrobial resistances, especially against essential oils or chemical preservatives used in the food industry.     

Quantitative Description of the Effects of Sweep Efficiency and Displacement Efficiency during Chemical Flooding on Heterogeneous Reservoir

The processes of flooding—water flooding, polymer flooding and ternary combination flooding—were simulated respectively on a 2-D positive rhythm profile geological model by using the ASP numerical modeling software developed by RIPED (Yuan, et al. 1995). The recovery coefficient, remaining oil saturation, sweep efficiency and displacement efficiency were calculated and correlated layer by layer. The results show that the sweep efficiency and displacement efficiency work different effects on different layers in the severely heterogeneous reservoir. The study shows that the displacement efficiency and sweep efficiency play different roles in different layers for severely heterogeneous reservoirs. The displacement efficiency contributes mainly to the high permeability zones, the sweep efficiency to the low permeability zones, both of which contribute to the middle permeable zones. To improve the sweep efficiency in the low permeability zones is of significance for enhancing the whole recovery of the reservoir. It is an important path for improving the effectiveness of chemical flooding in the severely heterogeneous reservoirs to inject ternary combination slug after profile control.     

A comparison of saturated steam and superheated steam for inactivation of Escherichia coli O157:H7, Salmonella Typhimurium,and Listeria monocytogenes biofilms on polyvinyl chloride and stainless steel

This study was performed to compare the effectiveness of saturated steam (SS) and superheated steam (SHS) in the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes biofilms on polyvinyl chloride (PVC) and stainless steel. Biofilms were formed on PVC and stainless steel coupons by using a mixture of three strains each of three foodborne pathogens at 25 °C. After biofilm development, PVC and stainless steel coupons were treated with SS at 100 °C and SHS at 125, 150, 175, and 200 °C for 5, 10, 20, and 30 s on both sides. The viable cell numbers of biofilms were significantly (p < 0.05) reduced as SHS temperature and exposure time increased. For all biofilm cells, SHS treatment resulted in an additional log reduction compared to SS treatments. After exposure to 200 °C steam for 30 s or 10 s on PVC or stainless steel, respectively, the numbers of biofilm cells were reduced to below the detection limit (1.48 log). This study demonstrated that SHS treatment effectively reduced populations of biofilm cells and reduced disinfection time compared to SS treatments and further evaluated its potential as an excellent intervention for controlling microbial biofilms and enhancing safety in the food processing industry.     

定量描述非均质油藏化学驱波及效率和驱替效率的作用

本文利用我国自行研制的ASP数值模拟软件,采用正韵律二维剖面地质模型,分别模拟了水驱、聚合物驱、三元复合驱的驱油过程,分层计算了采收率、剩余油饱和度、波及效率和驱替效率,进行了指标对比。通过研究表明对于非均质严重的油藏,不同层段的波及效率和驱替效率所起的作用不同。高渗层以提高驱替效率为主,低渗层以提高波及效率为主,中等渗透层提高波及效率和提高驱替效率相当。由于水驱后,剩余油大部分集中在上部,低渗透层是提高采收率主要潜力所在,提高上部低渗透层的波及效率对于提高总体采收率具有重要的作用。对于非均质严重的油藏,先调剖再注三元复合体系段塞是提高化学驱油效果的重要途径     

井场硫化氢传感器优选及安装位置研究

针对三高气田钻完井过程中硫化氢气体泄漏扩散和传感器检测问题,采用计算流体力学方法对井场泄漏的硫化氢气体在小范围内的分布进行模拟和分析,对气流与传感器入口夹角和气流速度对传感器输出值进行实验分析,从而优选传感器安装位置和安装方法。结果表明：在有风情况下,硫化氢气体在泄漏口小范围内主要分布在泄漏口下方向位置;根据硫化氢气体在气体中的扩散规律和不同检测点的检测环境,得出不同检测点传感器类型和安装高度。     

母源、沉积环境和成熟度对中性含氮化合物分布的影响

南翼山构造油气藏是目前柴西北区发现的最大油气藏。其深层E23是凝析气藏, 浅层N22是正常密度的油藏, 这种分布格局在柴西北区是唯一的, 对它进行成藏解剖对整个柴西北区的油气勘探具有重要的意义。结合原油轻烃、天然气碳同位素和生物标志化合物综合判识油源, 认为南翼山构造的N22与E23储集层原油来源不同, 深层E23油气来自E23烃源岩, 浅层N22的油来自N1 烃源岩; 南翼山构造的油气是就近捕获的产物, 不是从南边长距离运移而来, 深部凝析气藏的形成受有机质类型和成熟度共同控制。     

Recent advances in application of nanotechnology in chemical enhanced oil recovery: Effects of nanoparticles on wettability alteration,interfacial tension reduction,and flooding

Chemical methods of enhanced oil recovery (CEOR) are applied for improving oil recovery from different kinds of oil reservoirs due to their ability for modifying some crucial parameters in porous media, such as mobility ratio (M), wettability, spreading behavior of chemical solutions on rock surface and the interfacial tension (IFT) between water and oil. Few decades ago, the surfactant and polymer flooding were the most common CEOR methods have been applied for producing the remained hydrocarbon after primary and secondary recovery techniques. Recently, more attention has been focused on the potential applications of the nanotechnology in enhanced oil recovery (EOR). For this purpose, many studies reported that nanoparticles (NPs) have promising roles in CEOR processes due to their ability in changing oil recovery mechanisms and unlocking the trapped oil in the reservoir pore system. This paper presents a comprehensive and up-to-date review of the latest studies about various applications of nanoparticles (NPs) within the surfactant (S), polymer (P), surfactant-polymer (SP), alkaline-surfactant-polymer (ASP) and low salinity waterflooding processes, which exhibits the way for researchers who are interested in investigating this technology. The review covers the effects of nanoparticles on wettability alteration, interfacial tension reduction and oil recovery improvement, and discusses the factors affecting the rock/fluid interaction behavior in porous media through the nanofluid flooding.     

渤海湾盆地东营凹陷沙四上亚段—沙三下亚段岩相特征及沉积环境——以樊页1井为例

通过岩心、显微薄片的观察，依据有机质含量、无机矿物组成、沉积构造等特征，将渤海湾盆地东营凹陷沙河街组四段上亚段（沙四上亚段）-沙三下亚段樊页1井的细粒沉积岩划分出11种岩相类型。利用常量、微量元素含量及特定元素比值的垂向变化，从古气候、古物源、古水深、古盐度和古氧化还原性5个方面对沉积环境的垂向变化特征进行分析。研究层段发育的细粒沉积岩形成于半深湖-深湖、半咸水-咸水、相对湿润、还原-强还原的古环境条件，且环境的垂向演化具有明显的阶段性，经历了水体加深、盐度降低、气候由干旱转为湿润、强还原-弱还原-还原、陆源供给由多减少再增多的演化过程。5个沉积环境要素共同影响着岩相类型的垂向分布与组合特征。随水体加深，岩相组合中碳酸盐岩所占比重逐渐降低。不考虑重力流事件，岩石组分中石英、长石含量与水体深度、离岸距离、陆源碎屑供给量密切相关，从而影响粉砂岩及粉砂质细粒沉积岩的发育程度。高盐、强还原的水介质环境有利于有机质的保存，多形成富有机质岩相。古气候的变化使其他古环境要素也相应发生改变，进而影响岩相类型的分布与组合特征。     

天然气集输站场CH4及H2S泄漏检测技术研究

可调谐半导体激光吸收光谱技术是一种新型的气体检测方法,其技术关键是利用半导体激光器的窄线宽和可调谐等特性,结合长光程吸收池技术、波长调制技术,并辅以噪声压缩技术,对CH4、H2S分子的吸收线进行测量,从而实现对CH4、H2S气体泄漏的监测和报警.装置具有灵敏度高、选择性好、精度高、响应速度快和远距离遥测等优点.     

喷雾干燥对分子筛超稳化的影响及优化

采用喷雾干燥工艺生产超稳分子筛,晶胞常数的收缩问题是国内催化剂厂家面临的主要质量问题,单纯依靠提高温度的方法会造成晶体结构的破坏,结晶保留度低。结合超稳化过程的水热化学,分析了喷雾干燥对焙烧质量的影响,并提出了优化措施,使超稳分子筛的质量完全达到了指标     

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??Aimed at the reservoir characteristics of Lei-1 gas pool in Moxi gas field in the middle part of Sichuan,the reforming work on low permeability has being done in recent two years.The technology measures of bed rock aciding,preflush and gelling acid fracturing,as well as sand fracturing etc.are used.Through effect analysing and evaluating,the acid and sand fracturings are considered to be better than bed rock aciding.It is suggested that acid loss and slowing acid injected speed should be noticed;the sand fracturing should be improved in fracturing fluid properties and crosslinking way.     

C_5原料中C_4超标对双环戊二烯装置工艺控制及产品质量的影响

双环戊二烯装置对C_5原料中的C_4指标要求较高。针对辽阳石油化纤公司金兴化工厂双环戊二烯装置C_5原料中C_4含量严重超标的现象(由于上游裂解装置改造,使C_5原料中的C_4质量分数由2.13%增加到21.64%),从生产实际出发,阐述了C_5原料中C_4含量超标对双环戊二烯装置预处理系统、反应系统、常-减压系统及产品质量(产品中双环戊二烯质量分数由82%以上降至74%～79%)的影响,确定了相应的解决措施:减少装置进料量、提高反应器温度、降低脱苯塔负荷等,并建议在原料进入装置前增加C_4/C_5分离塔,以从根本上解决C_5原料中C_4含量超标对双环戊二烯装置工艺控制及产品质量的影响。     

磨溪气田雷一~1气藏低渗改造效果分析与评价

两年多来,针对川中磨溪气田雷一～1气藏储层特征,进行了低渗改造攻关。采用了基岩酸化、前置液酸压裂、胶凝酸酸压裂和加砂压裂等工艺措施。经过效果分析及评价,认为酸压裂如加砂压裂优于基岩酸化。建议磨溪气田酸压裂要重视控制酸滤失和缓速;加砂压裂要改进压裂液性能和交联方式。     

基于广义S变换地震高分辨率处理方法的改进及在流花11-1油田的应用

相比较早的小波变换和傅氏变换,广义S变换具有更好的时频局部性,但也存在低频信息易损失、弱反射层易丢失等问题.对基于广义S变换的地震高分辨率处理方法进行了改进,提出了新的处理思路.这种基于广义S变换的高分辨率处理技术,在提取并补偿高频信号的同时,也对低频信号进行了有效的保持.该项技术在流花11-1油田取得了良好的应用效果.