2,715 research outputs found

    Investigating Electronic, Optical, and Phononic Properties of Bulk γ-M<inf>2</inf>ON<inf>2</inf>and β-M<inf>7</inf>O<inf>8</inf>N<inf>4</inf>(M = Hf and Zr) Insulators Using Density Functional Theory

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    Hafnium and zirconium oxynitrides have similar properties, yet a consolidated investigation of their intrinsic properties has not been carried out. In this paper, we perform first-principles density functional theory calculations of γ- and β-phase hafnium and zirconium oxynitrides, which show that the γ-M2ON2(M = Hf and Zr) is an indirect band-gap (Eg) insulator, while the β-M7O8N4has a "pseudo-direct" type of Eg. β-phase has higher Egthan γ-phase, with concomitant disappearance of the conduction band tail. Optical properties in γ-M2ON2show that the anisotropy is negligible, and the optical constant values are in the range of other superhard materials. Phonon calculations present peculiar characteristics such as a small phonon band gap in γ-Hf2ON2and imaginary phonon frequencies in β-phases relating to lattice instability. The phononic properties are unfavorable for their potential use as an absorber material of the hot carrier solar cell-an emerging photovoltaic concept

    Systematic Review and Meta-analysis of Long-term survival After Elective Infrarenal Abdominal Aortic Aneurysm Repair 1969-2011: 5 Year Survival Remains Poor Despite Advances in Medical Care and Treatment Strategies.

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    BACKGROUND: Improved critical care, pre-operative optimization, and the advent of endovascular surgery (EVAR) have improved 30 day mortality for elective abdominal aortic aneurysm (AAA) repair. It remains unknown whether this has translated into improvements in long-term survival, particularly because these factors have also encouraged the treatment of older patients with greater comorbidity. The aim of this study was to quantify how 5 year survival after elective AAA repair has changed over time. METHODS: A systematic review was performed identifying studies reporting 5 year survival after elective infrarenal AAA repair. An electronic search of the Embase and Medline databases was conducted to January 2014. Thirty-six studies, 60 study arms, and 107,814 patients were identified. Meta-analyses were conducted to determine 5 year survival and to report whether 5 year survival changed over time. RESULTS: Five-year survival was 69% (95% CI 67 to 71%, I(2) = 87%). Meta-regression on study midpoint showed no improvement in 5 year survival over the period 1969-2011 (log OR -0.001, 95% CI -0.014-0.012). Larger average aneurysm diameter was associated with poorer 5 year survival (adjusted log OR -0.058, 95% CI -0.095 to -0.021, I(2) = 85%). Older average patient age at surgery was associated with poorer 5 year survival (adjusted log OR -0.118, 95% CI -0.142 to -0.094, I(2) = 70%). After adjusting for average patient age, an improvement in 5 year survival over the period that these data spanned was obtained (adjusted log OR 0.027, 95% CI 0.012 to 0.042). CONCLUSION: Five-year survival remains poor after elective AAA repair despite advances in short-term outcomes and is associated with AAA diameter and patient age at the time of surgery. Age-adjusted survival appears to have improved; however, this cohort as a whole continues to have poor long-term survival. Research in this field should attempt to improve the life expectancy of patients with repaired AAA and to optimise patient selection

    HALOGAS observations of NGC 4414: fountains, interaction, and ram pressure

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    We present deep H I imaging of the nearby spiral galaxy NGC 4414, taken as part of the Westerbork HALOGAS (Hydrogen Accretion in LOcal GAlaxieS) survey. The observations show that NGC 4414 can be characterized by a regularly rotating inner H I disk, and a more disturbed outer disk. Modeling of the kinematics shows that the outer disk is best described by a U-shaped warp. Deep optical imaging also reveals the presence of a low surface brightness stellar shell, indicating a minor interaction with a dwarf galaxy at some stage in the past. Modeling of the inner disk suggests that about 4 percent of the inner H I is in the form of extra-planar gas. Because of the disturbed nature of the outer disk, this number is difficult to constrain for the galaxy as a whole. These new, deep observations of NGC 4414 presented here show that even apparently undisturbed galaxies are interacting with their environment

    The Shapiro Design Lab Residency

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    A publication documenting the inaugural year of the Shapiro Design Lab Residency.https://deepblue.lib.umich.edu/bitstream/2027.42/142813/1/DesignLabResidency_Publication.pdfDescription of DesignLabResidency_Publication.pdf : PDF of publicatio

    Antipsychotic dose escalation as a trigger for Neuroleptic Malignant Syndrome (NMS): literature review and case series report

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    Background: “Neuroleptic malignant syndrome” (NMS) is a potentially fatal idiosyncratic reaction to any medication which affects the central dopaminergic system. Between 0.5% and 1% of patients exposed to antipsychotics develop the condition. Mortality rates may be as high as 55% and many risk factors have been reported. Although rapid escalation of antipsychotic dose is thought to be an important risk factor, to date it has not been the focus of a published case series or scientifically defined. &lt;p/&gt;Aims: To identify cases of NMS and review risk factors for its development with a particular focus on rapid dose escalation in the 30 days prior to onset. &lt;p/&gt;Methodology: A review of the literature on rapid dose escalation was undertaken and a pragmatic definition of “rapid dose escalation” was made. NMS cases were defined using DSM-IV criteria and systematically identified within a secondary care mental health service. A ratio of titration rate was calculated for each NMS patient and “rapid escalators” and “non rapid escalators” were compared. &lt;p/&gt;Results: 13 cases of NMS were identified. A progressive mean dose increase 15 days prior to the confirmed episode of NMS was observed (241.7mg/day during days 1-15 to 346.9mg/day during days 16-30) and the mean ratio of dose escalation for NMS patients was 1.4. Rapid dose escalation was seen in 5/13 cases and non rapid escalators had markedly higher daily cumulative antipsychotic dose compared to rapid escalators. &lt;p/&gt;Conclusions: Rapid dose escalation occurred in less than half of this case series (n=5, 38.5%), although there is currently no consensus on the precise definition of rapid dose escalation. Cumulative antipsychotic dose – alongside other known risk factors - may also be important in the development of NMS

    Enhanced Power Conversion Efficiency via Hybrid Ligand Exchange Treatment of p-Type PbS Quantum Dots.

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    PbS quantum dot solar cells (QDSCs) have emerged as a promising low-cost, solution-processable solar energy harvesting device and demonstrated good air stability and potential for large-scale commercial implementation. PbS QDSCs achieved a record certified efficiency of 12% in 2018 by utilizing an n+-n-p device structure. However, the p-type layer has generally suffered from low carrier mobility due to the organic ligand 1,2-ethanedithiol (EDT) that is used to modify the quantum dot (QD) surface. The low carrier mobility of EDT naturally limits the device thickness as the carrier diffusion length is limited by the low mobility. Herein, we improve the properties of the p-type layer through a two-step hybrid organic ligand treatment. By treating the p-type layer with two types of ligands, 3-mercaptopropionic acid (MPA) and EDT, the PbS QD surface was passivated by a combination of the two ligands, resulting in an overall improvement in open-circuit voltage, fill factor, and current density, leading to an improvement in the cell efficiency from 7.0 to 10.4% for the champion device. This achievement was a result of the improved QD passivation and a reduction in the interdot distance, improving charge transport through the p-type PbS quantum dot film
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