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1.
Mar Environ Res ; 198: 106532, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38718523

RESUMO

Environmental interactions of marine renewable energy developments vary from fine-scale direct (e.g. potential collision) to indirect wide-scale hydrodynamic changes altering oceanographic features. Current UK Environmental Impact Assessment (EIA) and associated Habitats Regulations Appraisal (HRA) guidelines have limited focus on underlying processes affecting distribution and movements (hence vulnerability) of top predators. This study integrates multi-trophic ship survey (active acoustics and observer data) with an upward-facing seabed platform and 3-dimensional hydrodynamic model as a process-driven framework to investigate predator-prey linkages between seabirds and fish schools. Observer-only data highlighted the need to measure physical drivers of variance in species abundances and distributions. Active acoustics indicated that in situ (preferable to modelled) data were needed to identify temporal changes in hydrodynamics to predict prey and consequently top predator presence. Revising methods to identify key habitats and environmental covariates within current regulatory frameworks will enable more robust and transferable EIA and HRA processes and outputs, and at larger scales for cumulative and strategic-level assessments, enabling future modelling of ecosystem impacts from both climate change and renewable energy extraction.


Assuntos
Ecossistema , Monitoramento Ambiental , Energia Renovável , Animais , Monitoramento Ambiental/métodos , Hidrodinâmica , Peixes/fisiologia , Mudança Climática , Aves/fisiologia , Conservação dos Recursos Naturais/métodos
2.
Phys Chem Chem Phys ; 26(4): 3350-3366, 2024 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-38198203

RESUMO

The second largest family of oxide ferroelectrics, after perovskites, are the tetragonal tungsten bronzes (TTB) with the general formula A24A12C4B12B28O30. Cation disorder in TTBs is known to occur if the size difference between cations is small, but the impact of cation disorder on structure and properties has not yet been extensively addressed. In this study we investigate the effect of the size of the M cation, including cation disorder, on the crystal structure and dielectric properties in the two series Ba4M2Nb10O30 (BMN, A = Na, K and Rb) and Ba4M2Nb8Ti2O30 (BMNT, M = Ca, Sr). Dense and phase pure ceramics in the two series were prepared by a two-step solid state synthesis route. The crystal structures of the materials were characterized by powder X-ray diffraction combined with Rietveld refinement. A close to linear relation between the in-plane lattice parameter (a) and the size of the M-cation were observed. Ba4M2Nb8Ti2O30 was shown to possess cation disorder on the A-sites in line with previous work on Ba4M2Nb10O30. Thermodynamic calculations from density functional theory also indicated a drive for cation disorder in the three BMN compositions. Non-ambient temperature X-ray diffraction revealed contraction of the in-plane (a) and expansion of the out-of-plane (c) lattice parameters at the ferroelectric phase transition for Ba4M2Nb10O30. The ferroelectric transition temperature acquired by dielectric spectroscopy showed a systematically increasing TC with decreasing size of the M-cation within both compositional series studied. The compositional dependence of TC is discussed with respect to the size of the M-cation, cation disorder and the tetragonality, as well as the Ti-content. The relaxor to ferroelectric properties observed by polarization-electric field hysteresis loops are discussed in relation to the relative size of cations on the on A1 and A2 sites and the Ti-content.

4.
Artigo em Inglês | MEDLINE | ID: mdl-38028916

RESUMO

Objective: To describe the development of a combined local antibiogram and assess its utility in an educational intervention. Design: Retrospective analysis of a combined, multi-healthcare system antibiogram with an educational intervention and pre-post analysis. Setting: Creation of the combined antibiogram included all health systems in Des Moines, Iowa. The educational intervention was delivered live via webinar and remained available on demand for one year. Participants: The combined antibiogram participants included four health systems representing eight hospitals. The educational intervention included 45 healthcare providers (15 live, 30 on demand) who elected to participate. Methods: Yearly antibiograms were collected from four health systems for 2017 and 2018 and from three health systems for 2019 and 2020. Each was aggregated into a single antibiogram, posted online, and analyzed retrospectively. In 2021, an educational intervention took place, which included pre-educational assessments, a one-hour presentation on local resistance rates and impact on common infections, and post-education assessments. The educational session was available online for one year. Correct responses before and after education were compared using NcNemar's test. Results: Over 4 yr, 123,168 isolates were included in the antibiogram, representing 57 species and 46 tested antibiotics. Before education, prediction of local resistance rates for E. coli and S. pneumoniae was poor. After the education session, there was improvement in the proportion of correct responses to case-based questions: pneumonia (31.8% vs 58.8%, P = 0.022), UTI (47.7% vs 85.3%, P < 0.001), sinusitis (75% vs 91.2%, P = 0.109), and diverticulitis (43.2% vs 88.2%, P = 0.002). Conclusions: A combined local antibiogram was useful in supporting an outpatient education program.

5.
J Mater Chem C Mater ; 10(10): 3784-3795, 2022 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-36325578

RESUMO

Four novel compositions containing chalcogenide layers, adopting the Ba3M2O5M'2Ch2 layered structure have been identified: Ba3Sc2O5Cu2Se2, Ba3Y2O5Cu2S2, Ba3Sc2O5Ag2Se2 and Ba3In2O5Ag2Se2. A comprehensive comparison of experimental and computational results providing the crystallographic and electronic structure of the compounds under investigation has been conducted. Materials were synthesised at 800 °C under vacuum using a conventional ceramic synthesis route with combination of binary oxide and chalcogenide precursors. We report their structures determined by Rietveld refinement of X-ray powder diffraction patterns, and band gaps determined from optical measurements, which range from 1.44 eV to 3.04 eV. Through computational modelling we can also present detailed band structures and propose that, based on their predicted transport properties, Ba3Sc2O5Ag2Se2 has potential as a visible light photocatalyst and Ba3Sc2O5Cu2Se2 is of interest as a p-type transparent conductor. These four novel compounds are part of a larger series of sixteen compounds adopting the Ba3M2O5M'2Ch2 structure that we have considered, of which approximately half are stable and can be synthesized. Analysis of the compounds that cannot be synthesized from this group allows us to identify why compounds containing either M = La, or silver sulfide chalcogenide layers, cannot be formed in this structure type.

6.
ACS Energy Lett ; 7(11): 3807-3816, 2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36398093

RESUMO

Transparent conducting oxides have become ubiquitous in modern optoelectronics. However, the number of oxides that are transparent to visible light and have the metallic-like conductivity necessary for applications is limited to a handful of systems that have been known for the past 40 years. In this work, we use hybrid density functional theory and defect chemistry analysis to demonstrate that tri-rutile zinc antimonate, ZnSb2O6, is an ideal transparent conducting oxide and to identify gallium as the optimal dopant to yield high conductivity and transparency. To validate our computational predictions, we have synthesized both powder samples and single crystals of Ga-doped ZnSb2O6 which conclusively show behavior consistent with a degenerate transparent conducting oxide. This study demonstrates the possibility of a family of Sb(V)-containing oxides for transparent conducting oxide and power electronics applications.

7.
Antimicrob Agents Chemother ; 66(1): e0162421, 2022 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-34633842

RESUMO

ERG11 sequencing of 28 Candida auris clade III isolates revealed the presence of concomitant V125A and F126L substitutions. Heterologous expression of Erg11-V125A/F126L in Saccharomyces cerevisiae led to reduced fluconazole and voriconazole susceptibilities. Generation of single substitution gene variants through site-directed mutagenesis uncovered that F126L primarily contributes to the elevated triazole MICs. A similar yet diminished pattern of reduced susceptibility was observed with the long-tailed triazoles posaconazole and itraconazole for the V125A/F126L, F126L, Y132F, and K143R alleles.


Assuntos
Candida auris , Farmacorresistência Fúngica , Substituição de Aminoácidos , Antifúngicos/farmacologia , Candida auris/efeitos dos fármacos , Candida auris/genética , Farmacorresistência Fúngica/genética , Fluconazol/farmacologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Testes de Sensibilidade Microbiana , Triazóis/farmacologia
8.
Proc Math Phys Eng Sci ; 477(2255): 20210469, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35153596

RESUMO

This review provides a critical, multi-faceted assessment of the practical contribution tidal stream energy can make to the UK and British Channel Islands future energy mix. Evidence is presented that broadly supports the latest national-scale practical resource estimate, of 34 TWh/year, equivalent to 11% of the UK's current annual electricity demand. The size of the practical resource depends in part on the economic competitiveness of projects. In the UK, 124 MW of prospective tidal stream capacity is currently eligible to bid for subsidy support (MeyGen 1C, 80 MW; PTEC, 30 MW; and Morlais, 14 MW). It is estimated that the installation of this 124 MW would serve to drive down the levelized cost of energy (LCoE), through learning, from its current level of around 240 £ / MWh to below 150 £ / MWh , based on a mid-range technology learning rate of 17%. Doing so would make tidal stream cost competitive with technologies such as combined cycle gas turbines, biomass and anaerobic digestion. Installing this 124 MW by 2031 would put tidal stream on a trajectory to install the estimated 11.5 GW needed to generate 34 TWh/year by 2050. The cyclic, predictable nature of tidal stream power shows potential to provide additional, whole-system cost benefits. These include reductions in balancing expenditure that are not considered in conventional LCoE estimates. The practical resource is also dependent on environmental constraints. To date, no collisions between animals and turbines have been detected, and only small changes in habitat have been measured. The impacts of large arrays on stratification and predator-prey interaction are projected to be an order of magnitude less than those from climate change, highlighting opportunities for risk retirement. Ongoing field measurements will be important as arrays scale up, given the uncertainty in some environmental and ecological impact models. Based on the findings presented in this review, we recommend that an updated national-scale practical resource study is undertaken that implements high-fidelity, site-specific modelling, with improved model validation from the wide range of field measurements that are now available from the major sites. Quantifying the sensitivity of the practical resource to constraints will be important to establish opportunities for constraint retirement. Quantification of whole-system benefits is necessary to fully understand the value of tidal stream in the energy system.

9.
Mar Pollut Bull ; 157: 111314, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32658679

RESUMO

We are at a crossroads where many nation states, including the United Kingdom of Great Britain and Northern Ireland (UK), are committing to increased electricity production from "green energy", of which tidal stream marine renewable energy is one such resource. However, many questions remain regarding the effects of tidal energy devices on marine wildlife, including seabirds, of which the UK has internationally important numbers. Guidelines are lacking on how best to use both well-established and novel survey methods to assess seabird use of tidal flow areas, leading to a data-rich but information poor (DRIP) situation. This review provides a conceptual framework for assessing the effects of tidal stream energy devices on seabirds, summarises current knowledge and highlights knowledge gaps. Finally, recommendations are given for how best to pursue knowledge on this topic.


Assuntos
Energia Renovável , Rios , Animais , Aves , Irlanda do Norte , Reino Unido
10.
Chem Mater ; 32(5): 1964-1973, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32296264

RESUMO

Transparent conducting oxides (TCOs) are ubiquitous in modern consumer electronics. SnO2 is an earth abundant, cheaper alternative to In2O3 as a TCO. However, its performance in terms of mobilities and conductivities lags behind that of In2O3. On the basis of the recent discovery of mobility and conductivity enhancements in In2O3 from resonant dopants, we use a combination of state-of-the-art hybrid density functional theory calculations, high resolution photoelectron spectroscopy, and semiconductor statistics modeling to understand what is the optimal dopant to maximize performance of SnO2-based TCOs. We demonstrate that Ta is the optimal dopant for high performance SnO2, as it is a resonant dopant which is readily incorporated into SnO2 with the Ta 5d states sitting ∼1.4 eV above the conduction band minimum. Experimentally, the band edge electron effective mass of Ta doped SnO2 was shown to be 0.23m 0, compared to 0.29m 0 seen with conventional Sb doping, explaining its ability to yield higher mobilities and conductivities.

11.
ACS Appl Mater Interfaces ; 12(13): 15348-15361, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32109038

RESUMO

Multifunctional thin films which can display both photocatalytic and antibacterial activity are of great interest industrially. Here, for the first time, we have used aerosol-assisted chemical vapor deposition to deposit highly photoactive thin films of Cu-doped anatase TiO2 on glass substrates. The films displayed much enhanced photocatalytic activity relative to pure anatase and showed excellent antibacterial (vs Staphylococcus aureus and Escherichia coli) ability. Using a combination of transient absorption spectroscopy, photoluminescence measurements, and hybrid density functional theory calculations, we have gained nanoscopic insights into the improved properties of the Cu-doped TiO2 films. Our analysis has highlighted that the interactions between substitutional and interstitial Cu in the anatase lattice can explain the extended exciton lifetimes observed in the doped samples and the enhanced UV photoactivities observed.


Assuntos
Antibacterianos/química , Cobre/química , Titânio/química , Raios Ultravioleta , Antibacterianos/farmacologia , Catálise , Escherichia coli/efeitos dos fármacos , Modelos Teóricos , Espectroscopia Fotoeletrônica , Staphylococcus aureus/efeitos dos fármacos , Termodinâmica
12.
Matter ; 3(3): 759-781, 2020 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-34708195

RESUMO

n-type transparent conductors (TCs) are key materials in the modern optoelectronics industry. Despite years of research, the development of a high-performance p-type TC has lagged far behind that of its n-type counterparts, delaying the advent of "transparent electronics"-based p-n junctions. Here, we propose the layered oxysulfide [Cu2S2][Sr3Sc2O5] as a structural motif for discovering p-type TCs. We have used density functional theory to screen 24 compositions based on this motif in terms of their thermodynamic and dynamic stability and their electronic structure, thus predicting two p-type TCs and eight other stable systems with semiconductor properties. Following our predictions, we have successfully synthesized our best candidate p-type TC, [Cu2S2][Ba3Sc2O5], which displays structural and optical properties that validate our computational models. It is expected that the design principles emanating from this analysis will move the field closer to the realization of a high figure-of-merit p-type TC.

13.
ACS Omega ; 4(1): 1449-1459, 2019 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-31459412

RESUMO

A simplistic and low-cost method that dramatically improves the performance of solution-grown hematite photoanodes for solar-driven water splitting through incorporation of nanohybrid metal oxide overlayers was developed. By heating the α-Fe2O3/SnO2-TiO2 electrode in an inert atmosphere, such as argon or nitrogen, the photocurrent increased to over 2 mA/cm2 at 1.23 V versus a reversible hydrogen electrode, which is 10 times higher than that of pure hematite under 1 sun (100 mW/cm2, AM 1.5G) light illumination. For the first time, we found a significant morphological difference between argon and nitrogen gas heat-treated hematite films and discussed the consequences for photoresponse. The origin for the enhancement, probed via theoretical modeling, stems from the facile incorporation of low formation energy dopants into the Fe2O3 layer at the interface of the metal oxide nanohybrid overlayer, which decreases recombination by increasing the electrical conductivity of Fe2O3. These dopants diffuse from the overlayer into the α-Fe2O3 layer readily under inert gas heat treatment. This simple yet effective strategy could be applied to other dopants to increase hematite performance for solar energy conversion applications.

14.
Mar Pollut Bull ; 144: 205-215, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31179990

RESUMO

Active acoustic sensors are widely used in oceanographic and environmental studies. Although many have nominal operating frequencies above the range of marine mammal hearing, they can produce out-of-band sound that may be audible to marine mammals. Acoustic emissions from four active acoustic transducers were characterized and compared to marine mammal hearing thresholds. All four transducers had nominal operating frequencies above the reported upper limit of marine mammal hearing, but produced measurable sound below 160 kHz. A spatial map of the acoustic emissions of each sonar is used to evaluate potential effects on marine mammal hearing when the transducer is continuously operated from a stationary platform. Based on the cumulative sound exposure level metric, the acoustic emissions from the transducers are unlikely to cause temporary threshold shifts in marine mammals, but could affect animal behavior. The extent of audibility is estimated to be, at most, on the order of 100 m.


Assuntos
Acústica/instrumentação , Comportamento Animal/fisiologia , Cetáceos/fisiologia , Monitoramento Ambiental/métodos , Audição/fisiologia , Som , Animais , Limiar Auditivo , Caniformia , Monitoramento Ambiental/instrumentação , Transdutores
15.
J Vet Med ; 2019: 5734590, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31058196

RESUMO

Rabies is a zoonotic lyssavirus of mammals that is a major public health threat due to the high mortality rate in humans who develop clinical symptoms. In the United States and other developed countries, the main reservoirs are wildlife species. In April 2017, a raccoon tested positive for rabies in Wise County, Virginia, with a second raccoon testing positive in May. Wise County, Virginia, is one of the few counties in western Virginia that is not endemic for raccoon rabies variant virus. Due to this fact, local, state, and federal agencies worked together to prevent and control the outbreak to stop the public health theat. The purpose of this study was to understand how professionals from these various agencies viewed the response efforts to the two rabid raccoons in 2017 and to determine what could be done to improve future responses. A list of responders from the different agencies involved in the outbreak in 2017 was created. Participants were recruited via email and those who agreed to be interviewed were contacted via telephone. Participants were asked a series of 13 questions pertaining to the 2017 outbreak to understand more about the strengths and weaknesses perceived during the outbreak. Of the 11 individuals contacted, six agreed to an interview. Data were analyzed utilizing a three-step qualitative analysis process which included the steps of open coding, audit trail, and axial coding. Staff and partnerships were identified as strengths of the response while funding, community, and region were identified as weaknesses of the response. It is hoped that by identifying different strengths and weaknesses through qualitative analysis this will aid in improving future responses.

16.
Chem Mater ; 31(7): 2577-2589, 2019 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-31031526

RESUMO

Modification of TiO2 to increase its visible light activity and promote higher performance photocatalytic ability has become a key research goal for materials scientists in the past 2 decades. One of the most popular approaches proposed this as "passivated codoping", whereby an equal number of donor and acceptor dopants are introduced into the lattice, producing a charge neutral system with a reduced band gap. Using the archetypal codoping pairs of [Nb + N]- and [Ta + N]-doped anatase, we demonstrate using hybrid density functional theory that passivated codoping is not achievable in TiO2. Our results indicate that the natural defect chemistry of the host system (in this case n-type anatase TiO2) is dominant, and so concentration parity of dopant types is not achievable under any thermodynamic growth conditions. The implications of passivated codoping for band gap manipulation in general are discussed.

17.
Chem Sci ; 9(41): 7968-7980, 2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30542551

RESUMO

Phosphorus doped tin(iv) oxide (P:SnO2) films have been synthesised by an aerosol assisted chemical vapour deposition route. Triethyl phosphate was used as the phosphorus dopant source. The phosphorus concentration in solution was found to be key to electrical properties, with concentrations between 0.25-0.5 mol% phosphorus giving the lowest resistivities of the deposited films. The conductivity of the films synthesised improved on doping SnO2 with phosphorus, with resistivity values of 7.27 × 10-4 Ω cm and sheet resistance values of 18.2 Ω â–¡-1 achieved for the most conductive films. Phosphorus doping up to 1.0 mol% was shown to improve visible light transmission of the deposited films. The phosphorus doping also had a significant effect on film morphology, with varying microstructures achieved. The films were characterised by X-ray diffraction, scanning electron microscopy, UV/vis spectroscopy, Hall effect measurements and X-ray photoelectron spectroscopy. The data generated was used to build computational models of phosphorus as a dopant for SnO2, showing that the phosphorus acts as a shallow one-electron n-type donor allowing for good conductivities. Phosphorus does not suffer from self-compensation issues associated with other dopants, such as fluorine.

18.
Rev Sci Instrum ; 89(7): 073105, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30068129

RESUMO

Hard X-ray photoelectron spectroscopy (HAXPES) has seen continuous development since the first experiments in the 1970s. HAXPES systems are predominantly located at synchrotron sources due to low photoionization cross sections necessitating high X-ray intensities, which limits the technique's availability to a wide range of users and potential applications. Here, a new laboratory-based instrument capable of delivering monochromated X-rays with an energy of 9.25 keV and a microfocused 30 × 45 µm2 X-ray spot is introduced. The system gives an excellent energy resolution of below 500 meV coupled with good X-ray intensity. It allows stable measurements under grazing incidence conditions to maximise signal intensities. This article outlines the instrument behavior, showcases applications including bulk and multilayer measurements, and describes the overall performance of the spectrometer. This system presents an alternative to synchrotron-based experimental end stations and will help expand the number and range of HAXPES experiments performed in the future.

19.
ACS Appl Mater Interfaces ; 9(21): 18031-18038, 2017 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-28492079

RESUMO

Nb2O5 is an important material able to exist in many polymorphs with unique optical properties and morphologies that are dependent on the synthetic route. Here we report a novel ambient-pressure chemical vapor deposition route to Nb2O5 via aerosol-assisted chemical vapor deposition. The amorphous as-deposited films were annealed in air to obtain the the three most stable crystal structures: orthorhombic, tetragonal, and monoclinic. The films were thoroughly characterized for their material properties, and an in-depth study into the optical properties was carried out using state-of-the-art hybrid functional theory that allowed more insight into the optical properties of the materials.

20.
J Mater Chem C Mater ; 4(28): 6761-6768, 2016 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-27774150

RESUMO

This paper reports the synthesis of the novel single-source precursor, [{(MeInAs t Bu)3}2(Me2InAs( t Bu)H)2] and the subsequent first report of aerosol-assisted chemical vapour deposition of InAs thin films. Owing to the use of the single-source precursor, highly crystalline and stoichiometric films were grown at a relatively low deposition temperature of 450 °C. Core level XPS depth profiling studies showed some partial oxidation of the film surface, however this was self-limiting and disappeared on etch profiles. Valence band XPS analysis matched well with the simulated density of state spectrum. Hall effect measurements performed on the films showed that the films were n-type with promising resistivity (3.6 × 10-3 Ω cm) and carrier mobility (410 cm2 V-1 s-1) values despite growth on amorphous glass substrates.

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