Cross-contamination and recontamination by Salmonella in foods: A review

The presence of Salmonella in foodstuffs represents an internationally accepted human health concern. Although Salmonella causes many foodborne disease outbreaks, there is little evidence to support cross-contamination as a major contributing factor. However, the paramount importance of preventing cross-contamination and recontamination in assuring the safety of foodstuffs is well known. Sources and factors linked to cross-contamination and recontamination of Salmonella in foods are reviewed in detail. Those foods which are not submitted to lethal treatment at the end of processing or which do not receive further treatment in the home deserves special attention. Salmonella cross-contamination and recontamination episodes have been connected to the following factors: poor sanitation practices, poor equipment design, and deficient control of ingredients. We also examine potential cross-contamination in the home. Cross-contamination and recontamination events at factory level evidence the difficulty encountered for eradicating this pathogen from the environment and facilities, highlighting the need to reinforce industry preventive control measures such as appropriate and standardized sanitation. Also, at consumer level, Public Health Authorities should install hygiene education programs in order to raise consumer awareness of the risks of cross-contamination in the home and their role in its prevention. Finally, a review on cross-contamination models of Salmonella spp. is presented.     

Estimating the probability of recontamination via the air using Monte Carlo simulations

Recontamination of food products can cause foodborne illnesses or spoilage of foods. It is therefore useful to quantify this recontamination so that it can be incorporated in microbiological risk assessments (MRA). This paper describes a first attempt to quantify one of the recontamination routes: via the air. Data on the number of airborne microorganisms were collected from literature and industries. The settling velocities of different microorganisms were calculated for different products by combining the data on aerial concentrations with sedimentation counts assuming that settling is under the influence of gravity only. Air movement is not explicitly considered in this study. Statistical analyses were performed to clarify the effect of different products and seasons on the number of airborne microorganisms and the settling velocity. For both bacteria and moulds, three significantly different product categories with regard to the level of airborne organisms were identified. The statistical distribution in these categories was described by a lognormal distribution. The settling velocity did not depend on the product, the season of sampling or the type of microorganism, and had a geometrical mean value of 2.7 mm/s. The statistical distribution of the settling velocity was described by a lognormal distribution as well. The probability of recontamination via the air was estimated by the product of the number of bacteria in the air, the settling velocity, and the exposed area and time of the product. For three example products, the contamination level as a result of airborne recontamination was estimated using Monte Carlo simulations. What-if scenarios were used to exemplify determination of design criteria to control a specified contamination level.     

The use of a human donor flora for recontamination following antibiotic decontamination

A method to prevent endogenous infections in patients and laboratory animals with an impaired immune capacity is the total decontamination of the gastrointestinal tract. This is performed by oral administration of nonabsorbable antibiotics. One of the disadvantages of total decontamination is the fact that especially after termination of this treatment the decontaminated individual is easily colonized with organisms from the environment. This is the result of the elimination of the anaerobic part of the microflora, which is responsible for the so-called colonization resistance (CR). This CR is the resistance against exogenous microorganisms to colonize the gastrointestinal tract. In the absence of an anaerobic flora, the colonizing microorganisms can reach abnormally high faecal concentrations, thus increasing the risk for infection. In mice, the implantation of an anaerobic, mouse-derived flora after termination of total decontamination resulted in the restoration of a good CR, as could be shown by orally challenging the animals with a strain of Escherichia coli. Therefore, an anaerobic microflora, free of potentially pathogenic microorganisms, which was isolated from a healthy human volunteer was administered to monkeys and patients after a decontamination period in an attempt to restore CR. In the monkeys, this human donor flora (HDF) did not reduce the faecal concentration of microorganisms that had colonized the gastrointestinal tract before the donor microflora had been established, in contrast to the findings in some of the patients. Qualitative analysis of the microflora of patients which were contaminated with the human donor flora showed that the CR is not of the same quality as is found in healthy individuals. This can be the result of the impaired immune capacity of the patients at the time of HDF implantation. However, the results obtained show that implantation of the HDF in monkeys and patients after a decontamination period allows reconventionalization without an undue risk of microbial infection.     

Quantifying and mapping ecosystem services supplies and demands: a review of remote sensing applications

Ecosystems provide services necessary for the livelihoods and well-being of people. Quantifying and mapping supplies and demands of ecosystem services is essential for continuous monitoring of such services to support decision-making. Area-wide and spatially explicit mapping of ecosystem services based on extensive ground surveys is restricted to local scales and limited due to high costs. In contrast, remote sensing provides reliable area-wide data for quantifying and mapping ecosystem services at comparatively low costs, and with the option of fast, frequent, and continuous observations for monitoring. In this paper, we review relevant remote sensing systems, sensor types, and methods applicable in quantifying selected provisioning and regulatory services. Furthermore, opportunities, challenges, and future prospects in using remote sensing for supporting ecosystem services' quantification and mapping are discussed.     

Quantifying stream-aquifer interactions through the analysis of remotely sensed thermographic profiles and in situ temperature histories

The interaction between surface and subsurface waters through hyporheic exchange and baseflow is critical to maintaining ecological health in streams. During warm periods, groundwater-surface water interactions have two primary effects on stream temperature: (1) cool groundwater discharging as baseflow lowers stream temperature and (2) hyporheic exchange buffers diurnal stream temperature variations. We demonstrate, for the first time, how high-resolution, remotely sensed forward-looking infrared (FLIR) images and instream temperature data can be used to quantify detailed spatial patterns of groundwater discharge to a 1.7 km reach of Cottonwood Creek in Plumas National Forest, CA. We quantifythe individual effects of baseflow and hyporheic exchange on stream temperatures by simulating the stream energy budget under different conceptual models of the stream-aquifer interaction. Observed spatial and temporal patterns of stream temperature are consistent with an increase in baseflow and hyporheic exchange within the middle, restored stream reach when compared to groundwater fluxes in the surrounding, unrestored reaches. One implication is that pond and plug stream restoration may improve the aquatic habitat by depressing maximum stream temperatures by > 3 degrees C (K).     

Quantifying phosphine penetration through the bark of pine (Pinus radiata D.Don) logs

Phosphine (PH₃) is used as an in-transit phytosanitary treatment (10-d fumigation period) for pine (Pinus radiata D.Don) logs exported from New Zealand to China. The ability of PH₃ to penetrate through the bark of the logs is not well known. We designed equipment to accurately quantify PH₃ penetration into the bark of wooden blocks (100 × 100 × 50 mm; n = 12) cut from the upper and lower trunk of recently harvested pine trees fumigated at 15 or 25 °C. Fumigations simulated commercial conditions consisting of two phases; phase I with 2.0 g m⁻³ of PH₃ for the first 5 days (1–120 h) and 1.5 g m⁻³ of PH₃ in phase II for the next 5 days (121–240 h). During the 10-d schedule, we achieved the required commercial CT (concentration × time) of ≥48,000 ppm h at both temperatures. Bark thickness (i.e., trunk location) did not significantly affect fumigant penetration. Phosphine penetration through the bark of the wooden blocks was greatest after each application, then the penetrated concentrations diminished over time. Greater penetration occurred at 15 °C than at 25 °C. Further studies are required to better understand the dynamics of PH₃ penetration particularly at lower temperatures and through insect-infested blocks.     

Quantifying carbon mitigation wedges in U.S. cities: near-term strategy analysis and critical review

A case study of Denver, Colorado explores the roles of three social actors-individual users, infrastructure designer-operators, and policy actors-in near-term greenhouse gas (GHG) mitigation in U.S. cities. Energy efficiency, renewable energy, urban design, price- and behavioral-feedback strategies are evaluated across buildings-facilities, transportation, and materials/waste sectors in cities, comparing voluntary versus regulatory action configurations. GHG mitigation impact depends upon strategy effectiveness per unit, as well as societal participation rates in various action-configurations. Greatest impact occurs with regulations addressing the vast existing buildings stock in cities, followed by voluntary behavior change in electricity use/purchases, technology shifts (e.g., to teleconferencing), and green-energy purchases among individual users. A portfolio mix of voluntary and regulatory actions can yield a best-case maximum of ~1% GHG mitigation annually in buildings and transportation sectors, combined. Relying solely on voluntary actions reduces mitigation rates more than five-fold. A portfolio analysis of climate action plans in 55 U.S. cities reveals predominance of voluntary outreach programs that have low societal participation rates and hence low GHG impact, while innovative higher-impact behavioral, technological, and policy/regulatory strategies are under-utilized. Less than half the cities capitalize on cross-scale linkages with higher-impact state-scale policies. Interdisciplinary field research can help address the mis-match in plans, actions, and outcomes.     

Hayat Kimya开拓肯尼亚市场

Hayat Kimya在肯尼亚推出了Molfix婴儿纸尿裤,正式在肯尼亚开展业务。此次主要推出两种产品:Molfix日用/夜用纸尿裤和Molfix婴儿拉拉裤。Hayat Kimya全球首席执行官Avni Kigili在发布会上表示,希望公司在两年内成为肯尼亚的市场领导者。她说:“肯尼亚是一个发展中国家,有着巨大的发展潜力,青年人口不断增长,地处非洲中部和东部的战略位置。Hayat希望通过提供Molfix品牌优质和创新产品,成为这个快速现代化和发展中国家的一部分。”     

目标:“零废料工厂”──雅图仕全厂践行节能减排

<正>鹤山雅图仕印刷有限公司(以下简称雅图仕)是一家港商独资企业,创办于1991年,为利奥纸品印刷集团成员,其主要产品包括精装书、儿童益智书、立体书、文具用品、贺卡、包装用品、礼盒、纸袋、游戏套装等,产品百分之百出口,远销欧、     

网络销售&工厂店

随着传统品牌不断加大线上拓展力度,其强大的资金实力、资源整合能力及品牌运作能力都将逐渐释放出来,誓与根基尚浅的淘品牌比肩,一场如火如荼的电商之争昭然若揭。本期重点报道我们一起探讨,在零售终端疲软,产品库存积压严重,纺织企业危机感沉重的今天,作为传统线下企业如何开拓渠道,加入日趋白热化的网络销售,抑或开设工厂店,难分伯仲却必须决断。     

Gas transfer through wine closures: A critical review

BackgroundGas transfer, and especially oxygen, through wine closures has been studied since the 90's. It started with the problem of premature oxidation in wine. To that purpose, different techniques, issued from food packaging and wine analysis, have been developed to measure gas permeation through wine stoppers.Scope and approachThe objectives of this review is, first, to briefly remind the basic knowledge of gas transfer through materials and applied to wine stoppers. Then, after a short survey about the techniques of measurement, a compilation of all currently available permeation data has been done using the international system of units (when conversion was possible). This finally allowed to establish a critical appraisal between the different methods and closures.Key findings and conclusionsAlthough relying on different principles, with different accuracy (and respective pros and cons), all methods are well suited to investigate gas transfer through closures. The manometric method appears as the most versatile one, allowing to study all gases with various sample geometry. Whatever the method used, it appears that the technical stoppers are the lowest permeable ones to gas transfer, followed by screwcaps, natural corks and synthetic stoppers. Finally, it is worthy to note that the diffusion coefficient, as an intrinsic parameter, is the most relevant parameter to characterize the gas barrier properties of wine stoppers.     

Quantifying the effect of medium composition on the diffusive mass transfer of hydrophobic organic chemicals through unstirred boundary layers

Unstirred boundary layers (UBLs) often act as a bottleneck for the diffusive transport of hydrophobic organic compounds (HOCs) in the environment. Therefore, a microscale technique was developed for quantifying mass transfer through a 100-microm thin UBL, with the medium composition of the UBL as the controllable factor. The model compound fluoranthene had to (1) partition from a contaminated silicone disk (source) into the medium, (2) then diffuse through 100 microm of medium (UBL), and finally (3) partition into a clean silicone layer (sink). The diffusive mass transfer from source to sink was monitored over time by measuring the fluoranthene content of the source and sink disks. The diffusive flux of fluoranthene was slightly higher for air than for water. Cyclodextrin, humic acids, and micelles of sodium dodecyl sulfate (SDS) enhanced the diffusive flux of fluoranthene in water by more than 1 order of magnitude. These results demonstrate that medium constituents, which normally are believed to bind hydrophobic organic chemicals, actually can enhance the diffusive mass transfer of HOCs in the vicinity of a diffusion source (e.g., contaminated soil particles). The technique can be used to evaluate the effect of natural fluids on diffusive mass transfer, as it integrates the different processes, partitioning and diffusion, in one laboratory model.     

Research Watch: Quantifying herbicides

Measurements.     

Quantifying the Pulp Refining Process

Pulp refining action is commonly described by one or more quantitative parameters to enable comparisons among refiners and optimization of individual refiners.Specific refining energy and refining intensity are the two most commonly used parameters.Both are energy-based,but recent work by this author has shown that additional parameters based on force are of benefit.This paper reviews the background and key aspects of this work.     

新建酱油厂的思考点滴

新建酱油厂应根据市场需要采用分步进行的方法达到生产规模。认为采用“低盐低温固稀发酵”加上后期半成品油“晒制增香”的生产工艺较为理想，并对相关的设备、车间卫生、防腐设计做了简要论述。     

厂内甜菜保藏技术措施

在甜菜保藏中,保管甜菜的基本任务是尽量延缓和控制甜菜堆中温度的升高,使甜菜和热空气隔绝,尽量利用外界气温缓慢降低和冷却甜菜堆,防止甜菜腐烂变质,为制糖加工生产提供优质原料。因此,深入研究甜菜保藏技术措施,对完成制糖生产任务,提高经济效益有重要意义。佳木斯赛瑞南华糖业有限公司,经过2000～2009年生产期的试验,提出厂内甜菜保藏技术措施。     

翡翠估价前期的数据量化

翡翠评估具有现实性、市场性以及预测性等特点,而传统的评估方法主要依赖评估人员的经验,其主观随意性较大,难以保证评估结果的客观性与公正性.针对翡翠价格与其质量因素之间的复杂、不确定关系,提出了运用特尔斐法判定各权重之间的关系,并利用数学方法计算各质量因素之间的权重,以减少因评估人员的主观因素而造成评估结果的偏差.该方法能迅速、准确、公正地对翡翠估价前期的数据进行量化处理.