255 research outputs found

    Hot Carrier extraction with plasmonic broadband absorbers

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    Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photo-catalysis, photovoltaics and photodetection. One limitation is that many metallic nanostructures support a single plasmon resonance thus restricting the light-to-charge-carrier activity to a spectral band. Here we demonstrate that a monolayer of plasmonic nanoparticles can be assembled on a multi-stack layered configuration to achieve broad-band, near-unit light absorption, which is spatially localised on the nanoparticle layer. We show that this enhanced light absorbance leads to \sim 40-fold increases in the photon-to-electron conversion efficiency by the plasmonic nanostructures. We developed a model that successfully captures the essential physics of the plasmonic hot-electron charge generation and separation in these structures. This model also allowed us to establish that efficient hot carrier extraction is limited to spectral regions where the photons possessing energies higher than the Schottky junctions and the localised light absorption of the metal nanoparticles overlap.Comment: submitte

    The final transformation of Étaín

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    Abstract Background Although serotonin (5-HT3) receptor antagonists are effective in reducing nausea and vomiting, they may be associated with increased cardiac risk. Our objective was to examine the comparative safety and effectiveness of 5-HT3 receptor antagonists (e.g., dolasetron, granisetron, ondansetron, palonosetron, tropisetron) alone or combined with steroids for patients undergoing chemotherapy. Methods We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from inception until December 2015 for studies comparing 5-HT3 receptor antagonists with each other or placebo in chemotherapy patients. The search results were screened, data were abstracted, and risk of bias was appraised by pairs of reviewers, independently. Random-effects meta-analyses and network meta-analyses (NMAs) were conducted. Results After screening 9226 citations and 970 full-text articles, we included 299 studies (n = 58,412 patients). None of the included studies reported harms for active treatment versus placebo. For NMAs on the risk of arrhythmia (primary outcome; three randomized controlled trials [RCTs], 627 adults) and mortality (secondary outcome; eight RCTs, 4823 adults), no statistically significant differences were observed between agents. A NMA on the risk of QTc prolongation showed a significantly greater risk for dolasetron + dexamethasone versus ondansetron + dexamethasone (four RCTs, 3358 children and adults, odds ratio 2.94, 95% confidence interval 2.13–4.17). For NMAs on the number of patients without nausea (44 RCTs, 11,664 adults, 12 treatments), number of patients without vomiting (63 RCTs, 15,460 adults, 12 treatments), and number of patients without chemotherapy-induced nausea or vomiting (27 RCTs, 10,924 adults, nine treatments), all agents were significantly superior to placebo. For a NMA on severe vomiting (10 RCTs, 917 adults), all treatments decreased the risk, but only ondansetron and ramosetron were significantly superior to placebo. According to a rank-heat plot with the surface under the cumulative ranking curve results, palonosetron + steroid was ranked the safest and most effective agent overall. Conclusions Most 5-HT3 receptor antagonists were relatively safe when compared with each other, yet none of the studies compared active treatment with placebo for harms. However, dolasetron + dexamethasone may prolong the QTc compared to ondansetron + dexamethasone. All agents were effective for reducing risk of nausea, vomiting, and chemotherapy-induced nausea or vomiting. Trial registration This study was registered at PROSPERO: ( CRD42013003564 )

    Synthesis of tungsten oxide for solar energy conversion and water splitting applications

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    In this thesis, a range of visible-light-active WO3 electrodes are fabricated by the electrochemical anodization method and studied for its solar energy conversion ability, predominantly as a photoanode for photoelectrochemical (PEC) reactions. The work starts with the synthesis of relatively thick flower-like nanostructured WO3 films by anodizing tungsten foil in fluoride-containing electrolyte under non-stirring static condition. The as-anodized samples comprise of monoclinic hydrated tungstite (WO3 2H2O), while films that were subsequently calcined contain predominantly monoclinic WO3. It was found that the supersaturation condition established during the anodization process favors the formation of the flower-structured WO3 2H2O through an anodization/precipitation-recrystallization process. The flower-structured films also exhibit higher photoresponse as compared to the typical mesoporous structure formed under similar anodization condition with non-static condition. Following the synthesis of these flower-structured WO3 films, a self-photorechargeability phenomenon was discovered with these WO3 films demonstrating simultaneous generation and storage of photo-excited electrons during PEC reactions. By introducing alkali cations such as Na+ and K+ in the electrolyte, the WO3 photoelectrode possessed the ability of storing light energy in the form of trapped electrons. Subsequently, the influence of crystallinity of the flower-structured WO3 films directed towards the optimization of both PEC water splitting and self-photorechargeability performance is also conducted. The effect of crystallinity was found to be crucial in the self-photorecharge property of these films. The last part of the thesis focuses on the development of bismuth tungstate (Bi2WO6) by transforming anodized flower-structured WO3 2H2O films into orthorhombic Bi2WO6 by hydrothermal treatment for PEC water splitting under visible light irradiation. The H2O molecules in the layered anodized WO3 2H2O film are proposed to be substituted by the [Bi2O2]2+ layers during the hydrothermal treatment process. The importance of an initial layered structure is also highlighted by the absence of Bi2WO6 formation in non-layered WO3 films

    Landscape and Traffic Factors Influencing Deer–Vehicle Collisions in an Urban Enviroment

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    Deer–vehicle collisions (DVCs) are steadily increasing across North America. The increase is particularly pronounced in urban green spaces where deer (Odocoileus spp.) populations and road densities are high. In the greater city of Edmonton, Alberta, Canada, 333 DVCs occurred from 2002 to 2004. To identify landscape and traffic correlates of these collisions, we built 3 statistical models. The first model assessed the importance of local variables and was based on a spatial precision of the nearest intersection to which collisions were referenced. The second model was based on landscape characteristics and used the nearest township intersection to aggregate collisions. For each of the models, we generated an equivalent number of random locations in a geographic information system (GIS) and examined several independent variables at 4 spatial scales (using 100-m, 200-m, 400-m, and 800-m radius buffers). We used multivariate logistic regression to determine which landscape and traffic factors increased the probability of a DVC. The third model used ordinal regression to assess correlates with collision frequency. Our first (High Precision) model showed that DVCs occurred in areas with high speed limits and low densities of roads within an 800-m buffer. The second (Aggregate) model found DVCs more likely to occur in areas close to water and the combination of high road densities and non-forested vegetation of high productivity within 800 m. The third (Hotspot) model identified only high traffic speed as a correlate of collision frequency. A temporal analysis of the collision data found that DVCs peaked in mid November. We conclude that rates of DVCs could be reduced and road safety improved by lowering speed limits during peak seasons, particularly in areas where road density is high (i.e., interchanges) and where non-forested vegetation occurs in close proximity to roads. Several aspects of our analyses and results may have applications in other jurisdictions where DVCs occur

    Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

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    Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

    Exploring RNF213 in Ischemic Stroke and Moyamoya Disease: From Cellular Models to Clinical Insights

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    Advances in stroke genetics have highlighted the critical role of rare genetic variants in cerebrovascular diseases, with RNF213 emerging as a key player in ischemic stroke and Moyamoya disease (MMD). Initially identified as the primary susceptibility gene for MMD, RNF213—notably the p.R4810K variant—has been strongly linked to intracranial artery stenosis (ICAS) and various ischemic stroke subtypes, particularly in East Asian populations. This gene encodes an E3 ubiquitin ligase with diverse roles in angiogenesis, vascular remodeling, lipid metabolism, and cerebral blood flow regulation, yet its exact mechanisms in cerebrovascular pathology remain incompletely understood. This review synthesizes findings from genetic studies, as well as cellular and animal models, to provide a holistic understanding of RNF213’s involvement in cerebrovascular diseases. Key mechanisms by which RNF213 variants contribute to disease pathogenesis are explored, alongside discussions on their clinical utility as biomarkers and therapeutic targets. Additionally, we address the gene’s implications for disease prediction, risk assessment, and cascade screening. By integrating evidence across disciplines, this review identifies critical knowledge gaps, including the biological pathways underlying RNF213’s pathogenicity. These insights lay the groundwork for future research and underscore the potential of RNF213 in driving personalized approaches to cerebrovascular disease management
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