1,417 research outputs found

    XPS and STEM study of the interface formation between ultra-thin Ru and Ir OER catalyst layers and perylene red support whiskers

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    The interface formation between nano-structured perylene red (PR) whiskers and oxygen evolution reaction (OER) catalysts ruthenium and iridium has been studied systematically by XPS and STEM. The OER catalyst over-layers with thicknesses ranging from ~0.1 to ~50 nm were vapor deposited onto PR ex-situ. STEM images demonstrate that, with increasing thickness, Ru and Ir transform from amorphous clusters to crystalline nanoparticles, which agglomerate with increased over-layer thickness. XPS data show a strong interaction between Ru and PR. Ir also interacts with PR although not to the extent seen for Ru. At low coverages, the entire Ru deposit is in the reacted state while a small portion of the deposited Ir remains metallic. Ru and Ir bonding occur at the PR carbonyl sites as evidenced by the attenuation of carbonyl photoemission and the emergence of new peak assigned to C-O single bond. The curve fitting analysis and the derived stoichiometry indicates the formation of metallo-organic bonds. The co-existence of oxide bonds is also apparent

    Inter-Annual Variability in Pasture Herbage Accumulation in Temperate Dairy Regions: Causes, Consequences, and Management Tools

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    Inter-annual variation in pasture herbage accumulation rate (HAR) is common in temperate dairy regions, posing challenges for farmers in the management of dairy cow feeding and of pasture state. This paper reviews the biophysical factors that cause inter-annual variation, considers some of its consequences for the efficient harvest of pasture, and discusses the basis for decision rules and support tools that are available to assist New Zealand and Australian farmers to help manage the consequences of an imbalance between feed supply and demand. These tools are well-grounded in scientific research and farmer experience, but are not widely used in the Australasian dairy industries. Some of the reasons for this are discussed. Inter-annual variability in HAR cannot be removed, even with inputs such as irrigation, but reliable forecasts of pasture HAR for a month or more could greatly improve the effectiveness of operational and tactical decision-making. Various approaches to pasture forecasting, based on pasture growth simulation models, are presented and discussed. Some of these appear to have reasonable predictive ability. However, considerably more development work is needed to: (1) prove their effectiveness; and (2) build the systems required to capture real-time, on farm data for critical systems variables such as pasture herbage mass and soil water content to combine with daily weather data. This technology presents an opportunity for farmers to gain greater control over variability in pasture-based dairy systems and improve the efficiency of resource use for profit and environmental outcomes

    Voltage gated inter-cation selective ion channels from graphene nanopores

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    With the ability to selectively control ionic flux, biological protein ion channels perform a fundamental role in many physiological processes. For practical applications that require the functionality of a biological ion channel, graphene provides a promising solid-state alternative, due to its atomic thinness and mechanical strength. Here, we demonstrate that nanopores introduced into graphene membranes, as large as 50 nm in diameter, exhibit inter-cation selectivity with a ~20x preference for K+ over divalent cations and can be modulated by an applied gate voltage. Liquid atomic force microscopy of the graphene devices reveals surface nanobubbles near the pore to be responsible for the observed selective behavior. Molecular dynamics simulations indicate that translocation of ions across the pore likely occurs via a thin water layer at the edge of the pore and the nanobubble. Our results demonstrate a significant improvement in the inter-cation selectivity displayed by a solid-state nanopore device and by utilizing the pores in a de-wetted state, offers an approach to fabricating selective graphene membranes that does not rely on the fabrication of sub-nm pores

    Distributions of Pigments and Primary Production in a Gulf-Stream Meander

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    An investigation was made of physical effects of Gulf Stream meandering on the vertical and horizontal distributions of photosynthetic pigments and primary production. Cruises were conducted in the vicinity of a meander east of 73-degrees-W and north of 37-degrees-N from September 21 to October 5 (leg 1) and October 12-21, 1988 (leg 2), on the R/V Cape Hatteras. Relationships of photosynthesis (normalized to chlorophyll) to irradiance (P-1) did not show large horizontal variation, and water column composite P-I curves from leg 1 and leg 2 were similar. Therefore a single P-I curve derived from pooled data was used to model distributions of primary production. Distributions of photosynthetic pigments were characterized on the basis of in vivo fluorescence profiles and empirical relationships with extracted pigment concentrations. Subsurface irradiance was described using a spectral irradiance model. Cross sections of the Gulf Stream revealed consistently higher pigment concentrations and primary production on the slope water side. Along-stream variations in pigment distributions and primary production were apparently related to density structure influenced by meander circulation. Such variations were less pronounced during leg 2. which came after a transition from a well-defined meander interacting with a warm-core ring (leg 1) to a more linear stream (leg 2). Higher water-column-integrated primary production during leg 2 was attributed to mixing-induced nutrient injection and redistribution of chlorophyll in the photic zone

    Individual-level and plant-level predictors of acute, traumatic occupational injuries in a manufacturing cohort

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    Objectives: Workplace and contextual factors that may affect risk for worker injury are not well described. This study used results from an employee job satisfaction survey to construct aggregate indicators of the work environment and estimate the relative contribution of those factors to injury rates in a manufacturing cohort. Methods: Principal components analysis was used to construct four plant-level factors from responses to a 32 question survey of the entire workforce, administered in 2006. Multilevel Poisson regression was used to evaluate the relationship between injury rate, individual-level and plant-level risk factors, unionisation and plant type. Results: Plant-level ‘work stress’ (incident rate ratio (IRR)=0.50, 95% CI 0.28 to 0.90) was significant in the multilevel model, indicating the rate of injury for an average individual in that plant was halved (conditional on plant) when job stress decreased by a tertile. ‘Overall satisfaction’, ‘work environment’ and ‘perception of supervisor’ showed the same trend but were not significant. Unionisation was protective (IRR=0.40, 95% CI 0.17 to 0.95) as was any plant type compared with smelter. Conclusions: We demonstrated utility of data from a human resources survey to construct indicators of the work environment. Our research suggests that aspects of the work environment, particularly work stress and unionisation, may have a significant effect on risk for occupational injury, emphasising the need for further multilevel studies. Our work would suggest monitoring of employee perceptions of job stress and the possible inclusion of stress management as a component of risk reduction programmes

    Racial/Ethnic Patterns in Prostate Cancer Outcomes in an Active Surveillance Cohort

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    Introduction. Concern regarding overtreatment of prostate cancer (CaP) is leading to increased attention on active surveillance (AS). This study examined CaP survivors on AS and compared secondary treatment patterns and overall survival by race/ethnicity. Methods. The study population consisted of CaP patients self-classified as black or white followed on AS in the Center for Prostate Disease Research (CPDR) multicenter national database between 1989 and 2008. Secondary treatment included radical prostatectomy (RP), external beam radiation therapy or brachytherapy (EBRT-Br), and hormone therapy (HT). Secondary treatment patterns and overall survival were compared by race/ethnicity. Results. Among 886 eligible patients, 21% were black. Despite racial differences in risk characteristics and secondary treatment patterns, overall survival was comparable across race. RP following AS was associated with the longest overall survival. Conclusion. Racial disparity in overall survival was not observed in this military health care beneficiary cohort with an equal access to health care

    Gender, Depression, and Blue-collar Work: A Retrospective Cohort Study of US Aluminum Manufacturers.

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    BACKGROUND: Industrial blue-collar workers face multiple work-related stressors, but evidence regarding the burden of mental illness among today's blue-collar men and women remains limited. METHODS: In this retrospective cohort study, we examined health and employment records for 37,183 blue- and white-collar workers employed by a single US aluminum manufacturer from 2003 to 2013. Using Cox proportional hazards regression, we modeled time to first episode of treated depression by gender and occupational class. Among cases, we modeled rates of depression-related service utilization with generalized gamma regression. RESULTS: Compared with their white-collar counterparts, blue-collar men were more likely to be treated for depression (hazard ratio [HR] = 1.3; 95% confidence interval [CI] = 1.1, 1.4) as were blue-collar women (HR = 1.4; 1.2, 1.6). Blue-collar women were most likely to be treated for depression as compared with white-collar men (HR = 3.2; 95% CI = 2.1, 5.0). However, blue-collar workers used depression-related services less frequently than their white-collar counterparts among both men (rate ratio = 0.91; 95% CI = 0.84, 0.98) and women (rate ratio = 0.82; 95% CI = 0.77, 0.88). CONCLUSIONS: Blue-collar women were more likely to be treated for depression than white-collar workers, and blue-collar women were most likely to be treated for depression compared with white-collar men. However, blue-collar men and women used depression-related healthcare services less frequently than white-collar workers. These findings underscore that blue-collar women may be uniquely susceptible to depression, and suggest that blue-collar workers may encounter barriers to care-seeking related mental illness other than their insurance status
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