Determination of free chlorine concentrations needed to prevent Escherichia coli O157:H7 cross-contamination during fresh-cut produce wash

This study was conducted to investigate the effect of free chlorine concentrations in wash water on Escherichia coli O157:H7 reduction, survival, and transference during washing of fresh-cut lettuce. The effectiveness of rewashing for inactivation of E. coli O157:H7 on newly cross-contaminated produce previously washed with solutions containing an insufficient amount of chlorine also was assessed. Results indicate that solutions containing a minimum of 0.5 mg/liter free chlorine were effective for inactivating E. coli O157:H7 in suspension to below the detection level. However, the presence of 1 mg/liter free chlorine in the wash solution before washing was insufficient to prevent E. coli O157:H7 survival and transfer during washing because the introduction of cut lettuce to the wash system quickly depleted the free chlorine. Although no E. coli O157:H7 was detected in the wash solution containing 5 mg/liter free chlorine before washing a mix of inoculated and uninoculated lettuce, low numbers of E. coli O157:H7 cells were detected on uninoculated lettuce in four of the seven experimental trials. When the prewash free chlorine concentration was increased to 10 mg/liter or greater, no E. coli O157:H7 transfer was detected. Furthermore, although rewashing newly cross-contaminated lettuce in 50 mg/liter free chlorine for 30 s significantly reduced (P = 0.002) the E. coli O157:H7 populations, it failed to eliminate E. coli O157:H7 on lettuce. This finding suggests that rewashing is not an effective way to correct for process failure, and maintaining a sufficient free chlorine concentration in the wash solution is critical for preventing pathogen cross-contamination.     

Comparison of annular diffusion denuder and high volume air samplers for measuring per- and polyfluoroalkyl substances in the atmosphere

Overestimation of the particle phase concentration collected on glass-fiber filters (GFFs) has been reported for perfluoroalkyl carboxylic acids (PFCAs) using conventional high volume air samplers. In this study, per- and polyfluoroalkyl substances (PFASs) were determined in the gas and particulate phases using colocated annular diffusion denuder and high volume air samplers at a semiurban site in Toronto, Canada, in winter 2010. Samples were analyzed for 7 PFAS classes (i.e., PFCAs, perfluoro-alkane sulfonic acids (PFSAs), fluorotelomer alcohols (FTOHs), fluorotelomer methacrylates (FTMACs), fluorotelomer acrylates (FTACs), perfluorooctane sulfonamides (FOSAs), and perfluorooctane sulfonamidoethanols (FOSEs)). The gas diffusion coefficients for individual PFASs were calculated and the denuder performance was evaluated. Modeled subcooled liquid vapor pressures (p(L)) correlated well with the vapor phase breakthrough for the denuder and high volume air systems. Total air concentrations for PFASs measured using annular diffusion denuders and high volume samplers were in agreement within a factor of 4; however, much greater differences were observed for measurements of gas-particle partitioning. Vapor phase PFSAs and PFCAs can adsorb to the GFF using high volume air samplers, resulting in much higher particle-associated fractions for these chemicals compared to the annular diffusion denuder sampler. This effect was not observed for the FTOHs, FTMACs, FTACs, FOSAs, and FOSEs. Thus, for investigations of gas-particle partitioning of PFSAs and PFCAs, the diffusion denuder sampler is the preferred method. The results of this study improve our understanding of the gas-particle partitioning of PFASs, which is important for modeling their long-range transport in air.     

Inlet ionization: a new highly sensitive approach for liquid chromatography/mass spectrometry of small and large molecules

Inlet ionization is a new approach for ionizing both small and large molecules in solids or liquid solvents with high sensitivity. The utility of solvent based inlet ionization mass spectrometry (MS) as a method for analysis of volatile and nonvolatile compounds eluting from a liquid chromatography (LC) column is demonstrated. This new LC/MS approach uses reverse phase solvent systems common to electrospray ionization MS. The first LC/MS analyses using this novel approach produced sharp chromatographic peaks and good quality full mass range mass spectra for over 25 peptides from injection of only 1 pmol of a tryptic digest of bovine serum albumin using an eluent flow rate of 55 μL min(-1). Similarly, full acquisition LC/MS/MS of the MH(+) ion of the drug clozapine, using the same solvent flow rate, produced a signal-to-noise ratio of 54 for the major fragment ion with injection of only 1 μL of a 2 ppb solution. LC/MS results were acquired on two different manufacturer's mass spectrometers using a Waters Corporation NanoAcquity liquid chromatograph.     

Temperature coefficient of the high-frequency guided acoustic mode in a photonic crystal fiber

High-frequency guided acoustic Brillouin modes have recently been observed in small-core silica photonic crystal fibers. In this paper, we investigate the temperature dependence of the optical sideband frequency generated by one of these guided acoustic waves. The experimental results show a temperature coefficient of 100 kHz/°C at an acoustic resonance frequency of 1.15 GHz and are in very good agreement with the theoretical predictions. This coefficient demonstrates a temperature sensitivity 10 times larger than that previously reported in conventional single-mode fibers, which is promising in view of potential applications to optical fiber sensors.     

Lapse-induced surges in craving influence relapse in adult smokers: An experimental investigation.

Objectives: Nearly all smokers who lapse experience a full-blown relapse, but the mediating mechanisms that contribute to this relationship are not well understood. A better understanding of these mechanisms would help to advance more effective relapse prevention treatments for smokers. The purpose of this study is to experimentally evaluate the effects of a programmed smoking lapse on smoking relapse and the effects of postlapse changes in craving on relapse. Method: Adult smokers (n = 63) who quit smoking with a brief cognitive–behavioral intervention and self-help materials were randomly assigned to one of two experimental conditions after 48 h of abstinence: No lapse (a no-smoking control/30-min waiting period) or lapse (smoking two cigarettes of their favored brand during a 30-min period). All participants were then followed daily for 14 days. Craving and biochemically verified self-reported abstinence were assessed on each follow-up day. Time (days) to relapse (7 consecutive days of smoking) was the main dependent measure. Results: Results of Cox regression analysis revealed that participants in the lapse condition relapsed more quickly than participants in the no-lapse condition (hazard ratio [HR] = 2.12, 95% confidence interval [CI] = [1.03, 4.35]). These effects were attributable, in part, to episodic increases in craving among participants in the lapse condition only (HR = 12.42, 95% CI =[2.00, 77.1]). Conclusions: Previously abstinent smokers who lapse are at risk for increased cigarette cravings and consequently, full-blown relapse. These results have implications for both cognitive–behavioral treatments for relapse prevention and for medications designed to help smokers manage cravings. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Striving to achieve it all: men and work-family-life balance in Sweden and the UK

Although there is a vast literature on issues of work-life balance, most of the research is grounded on the traditional view of work-life balance as a female-oriented entitlement. So far little attention has been paid to how men balance their work-life situations, especially the ‘new men’ who are keen to share the family care. We contribute to filling this gap by critically examining how male academics in construction-related departments at universities in Sweden and the UK construct their relationships with family and work. Narrative analysis was applied on in-depth interviews with seven academics from each country, who were at different phases in their careers. Three core narratives emerged from the data: family connected with partner; work as key priority; and desire to pursue personal projects, all of which competed for the narrators’ sparse time. The narrative that by far received most space and most storylines in all the interviews was ‘work as priority’, implying that in spite of gender equality policies and campaigns, work-life balance remains a female-oriented concern. Both Swedish and British men in our sample found juggling family and life most challenging. This work-family-life triad left many feeling that they had no time to do a good job in any sphere and in Sweden in particular combination pressure was intense. Curiously, despite these tensions and increasing demands for many of our respondents work remains a positive construct, possibly because of the strong conceptual identification of ‘self’ as an academic.     

Balancing employee needs,project requirements and organisational priorities in team deployment

The ‘people and performance’ model asserts that performance is a sum of employee ability, motivation and opportunity (AMO). Despite extensive evidence of this people–performance link within manufacturing and many service sectors, studies within the construction industry are limited. Thus, a recent research project set out to explore the team deployment strategies of a large construction company with the view of establishing how a balance could be achieved between organisational strategic priorities, operational project requirements and individual employee needs and preferences. The findings suggested that project priorities often took precedence over the delivery of the strategic intentions of the organisation in meeting employees’ individual needs. This approach is not sustainable in the long term because of the negative implications that such a policy had in relation to employee stress and staff turnover. It is suggested that a resourcing structure that takes into account the multiple facets of AMO may provide a more effective approach for balancing organisational strategic priorities, operational project requirements and individual employee needs and preferences more appropriately in the future.     

Community and Household Perceptions in Urban Services Demand

The narrow conception of rationality embodied in transportation planning is poorly suited to resolving goal conflicts. This article explores a broader view of what is rational, drawing on the ideas of communicative rationality. It offers a report from practice based on a case study of an access planning process at the Bay Area Rapid Transit District (BART). We consider propositions that the planning process enhanced deliberation about ends, improved issue framing through simultaneous engagement of means and ends, and enlarged the deliberative capacity of the organization. The article provides insights into these propositions and suggests ways that communicative rationality theory can improve transportation planning and policy.     

测量纱线长度和速度的非接触式传感器

介绍了一种新型测量纱线长度和速度的传感器,该传感器的功能已由实验证实.其原理是利用纱线上的静电荷进行非接触测量.所研制的传感器能用于测量各种原料纱线的长度和速度.在实际应用中,这种传感器可用于一些尚无经济实用解决方案的场合.     

A regional atmospheric fate and transport model for atrazine. 2. Evaluation

The Community Multiscale Air Quality (CMAQ) modeling system has been adapted to simulate the regional fate and transport of atrazine. Model modifications and simulations spanning April to mid-July 1995 are described in a previous paper. CMAQ results for atrazine concentrations in air and rainfall are evaluated against field observations taken along the Mississippi River and the shores of Lake Michigan in 1995. CMAQ results agree within 10% of published annual wet deposition load estimates for Lake Michigan and predicted annual dry deposition lies within published error bounds. Comparisons of weekly observed and predicted air and rainfall concentrations along the Mississippi River yield order-of-magnitude differences. Precipitation weighting of concentrations in rainfall good agreement for seasonal time frames. Weekly ambient gas form concentrations tend to be overpredicted by the CMAQ and semivolatile particulate fractons are underpredicted. Uncertainty in CMAQ predictions of air and rainfall concentrations for atrazine appear to derive primarily from uncertainty in emissions estimates, simulated precipitation, and spatial scale.