β-环糊精对曲拉通X-114紫外光谱抗干扰性能的影响

辛基苯基聚氧乙烯醚（曲拉通X-114）和脂肪醇聚氧乙烯醚（AEO-9）之间的相互作用能对水溶液中曲拉通X-114的紫外光谱产生明显影响。实验结果表明,在200～350nm范围内,曲拉通X-114的最大吸收波长为223nm,AEO-9的紫外吸光度接近于0;在水溶液中,AEO-9能减弱曲拉通X-114的紫外吸光度,降幅达3.4%;AEO-9还能显著降低曲拉通X-114的表观临界胶束浓度（cmc）,当AEO-9的浓度从0增加到0.050mmol/L 和0.100mmol/L时,曲拉通X-114的表观cmc从0.219mmol/L分别降至0.207mmol/L和0.202mmol/L。实验结果进一步表明,β-环糊精（β-CD）能有效降低AEO-9对曲拉通X-114的紫外吸光度及表观cmc的影响,在曲拉通 X-114和AEO-9复配水溶液中,按物质的量比1∶1加入β-CD,复配水溶液中曲拉通X-114的回收率从95.8%～103.3%变化至99.0%～100.1%,表明了β-CD能明显降低AEO-9对曲拉通X-114的干扰作用。红外光谱表征结果（FTIR）、核磁共振氢谱表征（¹H NMR）及热重差热分析表征结果（TG-DSC）表明,曲拉通X-114进入β-CD 分子空腔并形成包结物,是阻断曲拉通X-114分子形成混合胶束以及消除AEO对曲拉通X-114的干扰的主要原因。     

Sulfamethazine water medication pharmacokinetics and contamination in a commercial pig production unit

Sulfamethazine is often used to treat disease in the swine industry. Sulfamethazine is available as water or feed medication and historically (over the past 40 years) has been associated with residue violations in both the United States and Europe. Despite sulfamethazine's approval for use as a water medication, little research on the pharmacokinetics of the water formulation is available. Therefore, a pilot study was performed to determine the plasma levels of an approved sulfamethazine water medication. Plasma levels in pigs treated with an oral bolus (250 mg/kg), which is equivalent to the total drug consumed within a 24-h period, achieved therapeutic concentrations (50 microg/ml). Noncompartmental-based pharmacokinetic model parameters for clearance, half-life, and volume of distribution were consistent with previously published values in swine. However, the above treatment resulted in exposure of pen mates to sulfamethazine at levels currently above tolerance (0.1 ppm). Using a physiologically based pharmacokinetic model, the treatment dose simulation was compared with observed plasma levels of treated pigs. Flexibility of the physiologically based pharmacokinetic model also allowed simulation of control-pig plasma levels to estimate contamination exposure. A simulated exposure to 0.15 mg/kg twice within approximately 8 h resulted in detectable levels of sulfamethazine in the control pigs. After initial exposure, a much lower dose of 0.059 mg/kg maintained the contamination levels above tolerance for at least 3 days. These results are of concern for producers and veterinarians, because in commercial farms, the entire barn is often treated,and environmental contamination could result in residues of an unknown duration.     

Apportionment of primary and secondary organic aerosols in southern California during the 2005 study of organic aerosols in riverside (SOAR-1)

Ambient sampling was conducted in Riverside, California during the 2005 Study of Organic Aerosols in Riverside to characterize the composition and sources of organic aerosol using a variety of state-of-the-art instrumentation and source apportionmenttechniques. The secondary organic aerosol (SOA) mass is estimated by elemental carbon and carbon monoxide tracer methods, water soluble organic carbon content, chemical mass balance of organic molecular markers, and positive matrix factorization of high-resolution aerosol mass spectrometer data. Estimates obtained from each ofthese methods indicate that the organic fraction in ambient aerosol is overwhelmingly secondary in nature during a period of several weeks with moderate ozone concentrations and that SOA is the single largest component of PM1 aerosol in Riverside. Average SOA/OA contributions of 70-90% were observed during midday periods, whereas minimum SOA contributions of approximately 45% were observed during peak morning traffic periods. These results are contraryto previous estimates of SOAthroughout the Los Angeles Basin which reported that, other than during severe photochemical smog episodes, SOA was lower than primary OA. Possible reasons for these differences are discussed.     

Genotypic variation among arcobacter isolates from a farrow-to-finish swine facility

Arcobacter spp. were isolated from nursing sows and developing pigs on three farms of a farrow-to-finish swine operation and market-age pigs at slaughter. Isolates were identified by polymerase chain reaction and genotypic fragment patterns were examined by pulsed-field gel electrophoresis (PFGE). Incidences of Arcobacter-positive samples increased progressively as the pigs aged, resulting in all of the pens at the end of the growth cycle in the finishing barn containing Arcobacter-positive feces. However, only 10 of 350 cecal samples from slaughtered pigs were positive. There was little similarity between genotypic patterns for Arcobacter collected from the three farms. The level of genotypic variation revealed by PFGE suggested that pigs in this farrow-to-finish operation were colonized by multiple Arcobacter parent genotypes that may have undergone genomic rearrangement, common to members of Campylobacteraceae, during successive passages through the animals. Additionally, the level of genotypic diversity seen among Arcobacter isolates from farms of a single farrow-to-finish swine operation suggests an important role for genotypic phenotyping as a source identification and monitoring tool during outbreaks.     

油气田开发中不同井型钻井成本相关关系研究

在进行油气资源开采时,可以通过钻直井采油,也可以钻定向井、水平井、大位移井等采出油气。不同的井型对应着不同的钻井成本,引起不同的经济效益。因此,钻井成本的测算显得尤为重要。然而并不是每种井型的钻井成本都容易测算,比如水平井、大位移井技术难度大、钻遇情况复杂、不可预见因素多,成本测算就比较困难。文章运用统计学中等级相关系数辅以回归分析的方法,对5个油田的不同井型钻井成本数据进行了分析,确定了各井型的单位进尺成本之间存在等级相关性,并拟合出井型与单位进尺成本的关系曲线,最终得出了直井、定向井、水平井、大位移井的米成本呈e^0.4202倍增长的结论,为油气田进行钻井成本测算提供了捷径。     

模糊层次评价在油田产能建设投资中的应用

由于投资在油田产能建设当中占的比重很大,所以对油田产能建设当中投资的评价就显得相当重要。凭借已知的模糊层次评价模型,利用油田的实际开采状况得到的产量、井深、投资额的数据,形成了3个因素之间相互组合的不同的各种方案,并且运用敏感性分析方法来确定产量、井深、投资额的权重,对油田产能建设的投资进行相关的经济评价,最终结果以数值的行式表示出来,从而更加直观的确定最佳方案。对油田产能建设中投资规模的确定有着一定的现实意义和借鉴意义。     

Using radon risk to motivate smoking reduction: evaluation of written materials and brief telephone counselling

OBJECTIVE: Radon and cigarette smoking have synergistic effects on lung cancer, even when radon concentrations are relatively low. Working through an electric utility company, we sought to reach smoking households with low radon concentrations and motivate smoking cessation or prohibiting smoking in the home. DESIGN: Eligible homes (n = 714) were randomised to receive: (1) the Environmental Protection Agency's (EPA's) "A citizen's guide to radon"; (2) a specially developed pamphlet; or (3) that pamphlet plus brief telephone counselling. PROCEDURE: Utility company "bill stuffers" offered free radon test kits to smoking households. All households received radon test results with an explanatory cover letter. Both the specially developed pamphlet and the telephone counselling emphasised that smoking cessation or prohibiting smoking in the home were the optimal risk reduction strategies. Households were followed up at 3 and 12 months after receiving materials. RESULTS: The specially developed pamphlet and the EPA guide yielded similar outcomes. There was a non-significant trend for telephone counselling to produce greater sustained quitting than the specially developed pamphlet, and phone counselling led to significantly more new household smoking bans. CONCLUSIONS: Working through a public utility company is an efficient way to reach smoking households, and brief telephone counselling is a promising method for promoting household smoking bans and cessation in homes alerted to the risk posed by the combination of radon and smoking.     

Action of lysozyme and nisin mixtures against lactic acid bacteria

Lysozyme was formulated together with nisin for usage against food spoilage lactobacilli. The mixtures demonstrated improved minimal inhibitory concentrations (MIC), compared to the parent compounds, for many of the bacteria and media tested, including high salt media in which lysozyme lost virtually all of its activity. Synergy was also observed through measurement of the kinetics of bacterial killing of L. curvatus 845, in which strain synergy had been observed in MIC assays. The combination of lysozyme and nisin caused more severe cell damage as viewed by scanning electron microscopy, and a consequent change in optical density at 600 nm, compared to the parent compounds, effects that were presumed to reflect the action of lysozyme. In addition, the combination caused more rapid permeabilization (depolarization) of the cytoplasmic membranes of Staphylococcus aureus, an effect that reflected the mechanism of action of nisin. Thus, nisin and lysozyme appear to demonstrate synergy against gram-positive bacteria because they reinforce each others mechanisms of bacterial killing.     

Inhibition of surface spoilage bacteria in processed meats by application of antimicrobial films prepared with chitosan

A study was undertaken to evaluate the feasibility of using antimicrobial films, designed to slowly release bacterial inhibitors, to improve the preservation of vacuum-packaged processed meats during refrigerated storage. The antimicrobial films were prepared by incorporating acetic or propionic acid into a chitosan matrix, with or without addition of lauric acid or cinnamaldehyde, and were applied onto bologna, regular cooked ham, or pastrami. At various times during storage, packages were opened and the amounts of antimicrobial agents remaining in the chitosan matrix were measured. Regardless of film composition or meat product type, propionic acid was nearly completely released from the chitosan matrix within 48 h of application, whereas release of acetic acid was more limited, with 2-22% of the acid remaining in chitosan after 168 h of storage. Addition of lauric acid, but not cinnamaldehyde, to the chitosan matrix generally reduced the release of acetic acid significantly (P < or = 0.05) and the release was more limited onto bologna than onto ham or pastrami. In addition, the efficacies of the various films for inhibiting bacterial growth were tested against indigenous lactic acid bacteria and Enterobacteriaceae, and against Lactobacillus sakei or Serratia liqueficiens, surface-inoculated onto the meat products. Whereas lactic acid bacteria were not affected by the antimicrobial films under study, the growth of Enterobacteriaceae and S. liquefaciens was delayed or completely inhibited as a result of film application. Strongest inhibition was observed on drier surfaces (bologna), onto which acid release was slower, and with films containing cinnamaldehyde, as a result of its greater antimicrobial activity under these conditions.