6,073 research outputs found

    The direct hydrothermal deposition of cobalt-doped MoS2 onto fluorine-doped SnO2 substrates for catalysis of the electrochemical hydrogen evolution reaction

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    Metal chalcogenides, and doped molybdenum sulfides in particular, have considerable potential as earth-abundant electrocatalysts for the hydrogen evolution reaction. This is especially true in the case of solar-to-hydrogen devices, where an ability to deposit these materials on transparent substrates is therefore desirable. Hydrothermal methods are perhaps the most common route by which metal chalcogenide materials suitable for the hydrogen evolution reaction are produced. Such methods are simple and scalable, but the direct hydrothermal deposition of metal chalcogenides on transparent oxide electrodes has hitherto never been reported. Such an advance would greatly facilitate the expansion of the field by removing the requirement for separate hydrothermal-synthesis and catalyst-deposition steps. In this paper, we show that the ternary chalcogenide Co2Mo9S26 can be synthesised on a fluorine-doped tin oxide substrate by hydrothermal methods directly from solutions of the simple metal salts. These films display good activity for the hydrogen evolution reaction from acid solution, achieving current densities of 10 mA cm−2 at 260 mV overpotential with a Tafel slope of 64 mV per decade. Moreover, the resulting films can be made to be translucent, a very useful property which would allow light to be transmitted through the catalyst to an underlying light-harvesting array in any solar-to-hydrogen device employing this material at the cathode

    Market Reform in New Jersey and Quality of Care: A Cautionary Tale

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    As more than 40 states face present and projected deficits in their health care budgets, some legislatures are considering market-based reforms to control rising health care costs. This continues a trend begun in the 1990s that emphasized market competition over state regulation and mandates. However, little is known about the impact of many market-based reforms on quality of care. This Issue Brief evaluates the effect of one reform—the deregulation of hospital reimbursement rates in New Jersey—on one important outcome of care—mortality from acute myocardial infarction (heart attack). The findings serve as a reminder that cost-constraining reforms may reduce the quality of care, particularly for uninsured and other vulnerable populations

    Understanding the pathophysiological actions of tau oligomers : a critical review of current electrophysiological methods

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    Tau is a predominantly neuronal protein that is normally bound to microtubules, where it acts to modulate neuronal and axonal stability. In humans, pathological forms of tau are implicated in a range of diseases that are collectively known as tauopathies. Kinases and phosphatases are responsible for maintaining the correct balance of tau phosphorylation to enable axons to be both stable and labile enough to function properly. In the early stages of tauopathies, this balance is interrupted leading to dissociation of tau from microtubules. This leaves microtubules prone to damage and phosphorylated tau prone to aggregation. Initially, phosphorylated tau forms oligomers, then fibrils, and ultimately neurofibrillary tangles (NFTs). It is widely accepted that the initial soluble oligomeric forms of tau are probably the most pathologically relevant species but there is relatively little quantitative information to explain exactly what their toxic effects are at the individual neuron level. Electrophysiology provides a valuable tool to help uncover the mechanisms of action of tau oligomers on synaptic transmission within single neurons. Understanding the concentration-, time-, and neuronal compartment-dependent actions of soluble tau oligomers on neuronal and synaptic properties are essential to understanding how best to counteract its effects and to develop effective treatment strategies. Here, we briefly discuss the standard approaches used to elucidate these actions, focusing on the advantages and shortcomings of the experimental procedures. Subsequently, we will describe a new approach that addresses specific challenges with the current methods, thus allowing real-time toxicity evaluation at the single-neuron level

    Identifying robust response options to manage environmental change using an ecosystem approach:a stress-testing case study for the UK

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    A diverse range of response options was evaluated in terms of their utility for sustaining ecosystem services in the UK. Robustness of response options was investigated by applying a ‘stress-testing’ method which evaluated expected performance against combined scenarios of socioeconomic and climate change. Based upon stakeholder feedback, a reference scenario representing current trends in climate and socioeconomic drivers (‘business-as-usual’) was used as a dynamic baseline against which to compare results of other scenarios. The robustness of response options was evaluated by their utility in different environmental and social contexts as represented by the scenarios, and linked to their adaptability to adjust to changing conditions. Key findings demonstrate that adaptability becomes increasingly valuable as the magnitude and rate of future change diverges from current trends. Stress-testing also revealed that individual responses in isolation are unlikely to be robust meaning there are advantages from integrating cohesive combinations (bundles) of response options to maximise their individual strengths and compensate for weaknesses. This identifies a role for both top-down and bottom-up responses, including regulation, spatial targeting, incentives and partnership initiatives, and their use in combination through integrated assessment and planning consistent with the adoption of an Ecosystem Approach. Stress-testing approaches can have an important role in future-proofing policy appraisals but important knowledge gaps remain, especially for cultural and supporting ecosystem services. Finally, barriers and enablers to the implementation of more integrated long-term adaptive responses were identified drawing on the ‘4 Is’ (Institutions, Information, Incentives, Identity) conceptual framework. This highlighted the crucial but usually understated role of identity in promoting ownership and uptake of responses

    Development of a Fast Position-Sensitive Laser Beam Detector

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    We report the development of a fast position-sensitive laser beam detector with a bandwidth that exceeds currently available detectors. The detector uses a fiber-optic bundle that spatially splits the incident beam, followed by a fast balanced photo-detector. The detector is applied to the study of Brownian motion of particles on fast time scales with 1 Angstrom spatial resolution. Future applications include the study of molecule motors, protein folding, as well as cellular processes

    Wind Tunnel Results of the B-52B with the X-43A Stack

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    A low-speed wind-tunnel test was performed with a three-percent-scale model of a booster rocket mated to an X-43A research vehicle, a combination referred to as the Hyper-X launch vehicle. The test was conducted both in free-stream air and in the presence of a partial model of the B-52B airplane. The objectives of the test were to obtain force and moment data to generate structural loads affecting the pylon of the B-52B airplane and to determine the aerodynamic influence of the B-52B airplane on the Hyper-X launch vehicle to evaluate launch separation characteristics. The wind-tunnel test was conducted at a low-speed wind tunnel in Hampton, Virginia. All moments and forces reported are based either on the aerodynamic influence of the B-52B airplane or are for the Hyper-X launch vehicle in free-stream air. Overall, the test showed that the B-52B airplane imparts a strong downwash onto the Hyper-X launch vehicle, reducing the net lift of the Hyper-X launch vehicle. Also, pitching and rolling moments are imparted onto the booster and are a strong function of the launch-drop angle of attack

    Faculty Productivity, Seniority, and Salary Compression

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    For decades, many senior professors have noticed that the earnings of entry-level faculty are often very close to, or greater than their own. This trend in faculty life-cycle earnings can be illustrated by the 1998 salary and seniority data obtained from a public, liberal arts college (PLAC) that are reported in Table 1. Salary compression is evidenced by the narrow earnings difference (2,300)betweenthehighest−paidassistantprofessorandthelowest−paidfullprofessorinthisdepartment.Salaryinversioncanbeillustratedbydifferencesintheaverages,orintherangeofsalariesbetweenassistantandassociateprofessors.Forexample,theaverageassistantprofessorinDepartmentXearnsapproximately2,300) between the highest-paid assistant professor and the lowest-paid full professor in this department. Salary inversion can be illustrated by differences in the averages, or in the range of salaries between assistant and associate professors. For example, the average assistant professor in Department X earns approximately 200 more than the average associate professor. Also, the highest paid assistant in this department earns $2,000 more than the highest-paid associate. These data indicate a U-shaped wage-tenure profile. Such a profile suggests that faculty with low levels of seniority can expect their earnings to fall, or invert, relative to the salaries of new hires as their careers unfold at this institution. Similarly, the earnings gap between new hires and faculty with high levels of seniority will compress over time.Productivity; Salary; Seniority
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