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1.
Nature ; 600(7890): 659-663, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34937896

RESUMO

The increasing demand for next-generation energy storage systems necessitates the development of high-performance lithium batteries1-3. Unfortunately, current Li anodes exhibit rapid capacity decay and a short cycle life4-6, owing to the continuous generation of solid electrolyte interface7,8 and isolated Li (i-Li)9-11. The formation of i-Li during the nonuniform dissolution of Li dendrites12 leads to a substantial capacity loss in lithium batteries under most testing conditions13. Because i-Li loses electrical connection with the current collector, it has been considered electrochemically inactive or 'dead' in batteries14,15. Contradicting this commonly accepted presumption, here we show that i-Li is highly responsive to battery operations, owing to its dynamic polarization to the electric field in the electrolyte. Simultaneous Li deposition and dissolution occurs on two ends of the i-Li, leading to its spatial progression toward the cathode (anode) during charge (discharge). Revealed by our simulation results, the progression rate of i-Li is mainly affected by its length, orientation and the applied current density. Moreover, we successfully demonstrate the recovery of i-Li in Cu-Li cells with >100% Coulombic efficiency and realize LiNi0.5Mn0.3Co0.2O2 (NMC)-Li full cells with extended cycle life.

2.
Am J Obstet Gynecol ; 226(3): 347-365, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34534498

RESUMO

BACKGROUND: Postpartum hemorrhage causes a quarter of global maternal deaths. The World Health Organization recommends oxytocin as the first line agent to prevent hemorrhage during cesarean delivery. However, some randomized controlled trials suggest that other uterotonics are superior. OBJECTIVE: We conducted a network meta-analysis comparing the ability of pharmacologic agents to reduce blood loss and minimize the need for additional uterotonics during cesarean delivery. DATA SOURCES: We searched the Cochrane Central Register of Controlled Trials, Embase, and MEDLINE databases from inception to May 2020. STUDY ELIGIBILITY CRITERIA: We included randomized controlled trials that compared oxytocin, carbetocin, misoprostol, ergometrine, carboprost, or combinations of these in the prevention of postpartum hemorrhage during cesarean delivery. METHODS: We performed a systematic review followed by an NMA in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Quality of the evidence was assessed with the Confidence in Network Meta-Analysis approach and Grading of Recommendations, Assessment, Development and Evaluations tool within the summary of findings table. Our primary outcomes were the estimated blood loss and need for additional uterotonics. Secondary outcomes included nausea and postpartum hemorrhage of >1000 mL. We performed sensitivity analyses to explore the influence of surgical context and oxytocin administration strategy. RESULTS: A total of 46 studies with 7368 participants were included. Of those, 21 trials (6 agents and 3665 participants) formed the "estimated blood loss" network and, considering the treatment effects, certainty in the evidence, and surface under the cumulative ranking curve scores, carbetocin was assessed to probably be superior to oxytocin, but only in reducing the estimated blood loss by a clinically insignificant volume (54.83 mL; 95% confidence interval, 26.48-143.78). Misoprostol, ergometrine, and the combination of oxytocin and ergometrine were assessed to probably be inferior, whereas the combination of oxytocin and misoprostol was assessed to definitely be inferior to oxytocin. A total of 37 trials (8 agents and 6193 participants) formed the "additional uterotonic" network and, again, carbetocin was assessed to probably be superior to oxytocin, requiring additional uterotonics 185 (95% confidence interval, 130-218) fewer times per 1000 cases. Oxytocin plus misoprostol, oxytocin plus ergometrine, and misoprostol were assessed to probably be inferior, whereas carboprost, ergometrine, and the placebo were definitely inferior to oxytocin. For both primary outcomes, oxytocin administration strategies had a higher probability of being the best uterotonic, if initiated as a bolus. CONCLUSION: Carbetocin is probably the most effective agent in reducing blood loss and the need for additional uterotonics. Oxytocin appears to be more effective when initiated as a bolus.


Assuntos
Carboprosta , Misoprostol , Ocitócicos , Hemorragia Pós-Parto , Ergonovina/uso terapêutico , Feminino , Humanos , Misoprostol/uso terapêutico , Metanálise em Rede , Ocitócicos/uso terapêutico , Ocitocina/uso terapêutico , Hemorragia Pós-Parto/tratamento farmacológico , Hemorragia Pós-Parto/prevenção & controle , Gravidez
3.
BMC Pregnancy Childbirth ; 22(1): 786, 2022 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-36271352

RESUMO

BACKGROUND: Evidence suggests ketamine may prevent postpartum depression (PPD) after cesarean delivery (CD) although intolerability and inconvenience of administration are problematic. We assessed the feasibility of studying ketamine (0.5 mg/kg, via subcutaneous injection or 40-min intravenous infusion) to prevent PPD after CD. METHODS: Twenty-three women scheduled for cesarean delivery under neuraxial anesthesia were randomized to one of three groups: subcutaneous ketamine (SC Group, n = 8), intravenous ketamine (IV Group, n = 8) or placebo (n = 7). We measured depression (Edinburgh Postpartum Depression Scale [EPDS]) scores pre-operatively and at 1, 2, 21 and 42 days postoperatively. Anxiety, adverse effects, surgical site pain and analgesic consumption were also assessed. Feasibility was assessed based on acceptability, burden of disease, ability to collect study data and, tolerability of interventions. RESULTS: Baseline characteristics of groups were similar, however, more women in the placebo group had pre-existing anxiety disorder (p = 0.03). 20.7% (25/121) of those approached consented to participate and 34.8% (8/23), of those assessed, screened positive for depression in the postpartum (EPDS > 12). PPD screening data was complete in 78.3% (18/23). No differences were observed for any adverse effect outcomes except for fewer incidences of intraoperative shivering with ketamine (SC: 25%, IV: 0% and Placebo: 85.7%, p = 0.01). No statistically significant difference in positive screening for PPD was observed (SC: 14.3%, IV: 50% and Placebo: 42.9%, p = 0.58). CONCLUSION: An RCT was judged to be feasible and there was no evidence of intolerability of either route of ketamine administration. Dispensing with the need for intravenous access makes the subcutaneous route a particularly attractive option for use in the postpartum population. Further examination of these interventions to prevent, and possibly treat, postpartum depression is warranted. TRIAL REGISTRATION: NCT04227704, January 14th, 2020.


Assuntos
Anestesia , Depressão Pós-Parto , Ketamina , Gravidez , Feminino , Humanos , Estudos de Viabilidade , Depressão Pós-Parto/prevenção & controle , Depressão Pós-Parto/tratamento farmacológico , Projetos Piloto
4.
Behav Sleep Med ; 19(2): 232-242, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32088994

RESUMO

Objective/Background: Dysfunctional sleep-related cognitions (SRCs) have been demonstrated in both insomnia and depression, but have not been evaluated in patients experiencing depression with co-occurring hypersomnolence. Given the prominence of maladaptive thinking in depression with comorbid insomnia, dysfunctional SRCs may also exist in depressed persons experiencing hypersomnolence. Identifying potentially maladaptive SRCs may assist development of cognitive-behavioral strategies to alleviate hypersomnolence and its related impairment, particularly when comorbid with depression. Participants: Twenty-two unmedicated persons with major depressive disorder (MDD) with comorbid hypersomnolence (MDD+/HYP+), as well as age- and sex-matched persons with MDD without hypersomnolence (MDD+/HYP-) and healthy controls (HC). Methods: Participants completed the Dysfunctional Beliefs and Attitudes About Sleep-16-item (DBAS-16) and underwent overnight polysomnography. Groups were compared across clinical and sleep domains, as well as DBAS-16 global, subscale, and individual item scores. Additional analyses evaluated DBAS-16 components while controlling for depression severity. Results: Groups significantly differed across all collected sleep and mood metrics consistent with diagnostic classification. MDD+/HYP+ DBAS-16 global score was significantly elevated, relative to HC, and was comparable to MDD+/HYP-. A DBAS-16 global score significant group effect was maintained while controlling for depression symptom severity, however only individual DBAS-16 items related to quantity and quality of sleep demonstrated particular relevance to MDD+/HYP+ compared to other groups. Conclusions: Results suggest potentially maladaptive SRCs in MDD+/HYP+. Further efforts are needed to clarify whether these beliefs and attitudes about sleep in persons with hypersomnolence are in fact dysfunctional, as well as identify relevant content for development of a novel hypersomnolence-related SRC metric.


Assuntos
Atitude Frente a Saúde , Transtorno Depressivo Maior/complicações , Distúrbios do Sono por Sonolência Excessiva/complicações , Distúrbios do Início e da Manutenção do Sono/complicações , Distúrbios do Início e da Manutenção do Sono/psicologia , Adulto , Ansiedade/psicologia , Estudos de Casos e Controles , Cognição , Transtorno Depressivo Maior/psicologia , Distúrbios do Sono por Sonolência Excessiva/psicologia , Humanos , Masculino , Pessoa de Meia-Idade , Polissonografia , Sono , Inquéritos e Questionários
5.
Proc Natl Acad Sci U S A ; 115(34): 8529-8534, 2018 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-30082382

RESUMO

Lithium stripping is a crucial process coupled with lithium deposition during the cycling of Li metal batteries. Lithium deposition has been widely studied, whereas stripping as a subsurface process has rarely been investigated. Here we reveal the fundamental mechanism of stripping on lithium by visualizing the interface between stripped lithium and the solid electrolyte interphase (SEI). We observed nanovoids formed between lithium and the SEI layer after stripping, which are attributed to the accumulation of lithium metal vacancies. High-rate dissolution of lithium causes vigorous growth and subsequent aggregation of voids, followed by the collapse of the SEI layer, i.e., pitting. We systematically measured the lithium polarization behavior during stripping and find that the lithium cation diffusion through the SEI layer is the rate-determining step. Nonuniform sites on typical lithium surfaces, such as grain boundaries and slip lines, greatly accelerated the local dissolution of lithium. The deeper understanding of this buried interface stripping process provides beneficial clues for future lithium anode and electrolyte design.

6.
Health Promot J Austr ; 32 Suppl 2: 351-357, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33108670

RESUMO

ISSUE ADDRESSED: Smoking near hospital entrances occurs frequently despite smoke-free policies, resulting in multiple issues including second-hand smoke exposure (SHS) to vulnerable populations. Primary school children were engaged through their health curriculum to produce antismoking audio recordings for broadcast over a hospital entrance loudspeaker system to determine if this reduced smoking. METHOD: Students produced original recordings against hospital grounds smoking during class workshops, from which a collection (n = 16) was selected. Episodes of entrance smoking and total entrance traffic were recorded using security camera infrastructure over a 5-week period. A computer-controlled entrance loudspeaker played a message which was followed by silence until a new (different) message was played. Intensity of messaging was moderate in week 3 (every 5 minutes), increasing to high in week 4 (3 minutely) and compared to no messages (weeks 1-2 preintervention) and week 5 (postintervention). RESULTS: Smokers presented 316 times, smoking 523 cigarettes over 155 hours of observation (patients 70.6%, visitors 29.4%). SHS exposure was high given 172 others used the entrance/hour. Smoking was highest in the preintervention period (weeks 1-2), median five cigarettes/hr [IQR,3-7 (min = 0, max = 12)], falling to four cigarettes/hr during 5-minutely broadcasts [IQR,2-5 (min = 1, max = 14)] (P = .06), but zero cigarettes/hr during 3-minutely broadcasts [IQR,0-1(min = 0, max = 7)] (P < .0001). Postintervention (no broadcasts), smoking increased from zero to 1 cigarette/hr [IQR,0-3 (min = 0, max = 5)]; (P = .052). Nonsmoker movements did not change significantly between each period. CONCLUSION: Intensive (3 minutely) broadcasting of short antismoking messages significantly reduced hospital entrance smoking. SO WHAT?: Health services can positively interact with the health curriculum of primary schools against tobacco use while developing low-cost strategies to effectively deter entrance smoking.


Assuntos
Política Antifumo , Poluição por Fumaça de Tabaco , Austrália , Criança , Hospitais , Humanos , Instituições Acadêmicas , Fumar
7.
Planta ; 252(5): 80, 2020 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-33037481

RESUMO

MAIN CONCLUSION: This study highlights the potential link between high light-induced canopy-level photosynthesis and mesophyll cell K+, Cl-, Ca2+, and H+ homeostasis in tomato. Light is a primary energy source for photosynthesis and a vital regulator of mineral nutrient uptake and distribution in plants. Plants need to optimize photosynthesis and nutrient balance in leaves for performance in fluctuating light conditions that are partially regulated by light-induced ion homeostatsis in the mesophyll cells. It is still elusive whether high light-induced leaf mesophyll ion fluxes affect leaf photosynthesis at different canopy levels in Solanum lycopersicum L. Leaf gas exchange and microelectrode ion flux (MIFE) measurements were employed to study the effects of prolonged light-induced canopy-level leaf physiological responses of tomato plants. High light resulted in a significant lowering in photosynthesis in the fully-exposed top canopy leaves of tomato, but not to mid- or low-canopy leaves. Leaf mesophyll K+ effluxes of all canopies were significantly decreased after three weeks of high light treatment. However, high light-induced leaf mesophyll Ca2+ effluxes were significantly enhanced only in the top and mid canopies. Moreover, we found that photosynthetic parameters were significantly correlated with leaf mesophyll ion fluxes. We thus propose that canopy-level significant Ca2+ efflux and K+ efflux of leaf mesophyll may serve as early indicators for light-induced regulation on photosynthesis. We conclude that light-induced differential photosynthetic performance and ion fluxes in leaves may implicate a requirement of more uniform light irradiance and spectra at different canopy levels of tall greenhouse tomato plants. This can be achieved through new innovative greenhouse lighting technologies and covering materials towards the enhancement of crop photosynthesis and yield.


Assuntos
Luz , Células do Mesofilo , Fotossíntese , Solanum lycopersicum , Solanum lycopersicum/fisiologia , Células do Mesofilo/efeitos da radiação , Fotossíntese/efeitos da radiação , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação
8.
Rapid Commun Mass Spectrom ; 34(5): e8604, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31756774

RESUMO

RATIONALE: Strontium isotopes are valuable markers of provenance in a range of disciplines. Limited amounts of Sr in low-mass samples such as insects mean that conventional Sr isotope analysis precludes their use for geographic origins in many ecological studies or in applications such as biosecurity. Here we test the viability of using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) with N2 O as a reaction gas for accurately determining Sr isotopes in insects with Sr < 100 ng. METHODS: Strontium isotopes were determined in solution mode using ICP-MS/MS with 0.14 L/min N2 O as a reaction gas to convert Sr+ into SrO+ for in-line separation of 87 Sr from 87 Rb. The Sr isotope reference standards NIST SRM 987, NIST SRM 1570a and NIST SRM 1547 were used to assess accuracy and reproducibility. Ten insect species collected from the wild as a proof-of-principle application were analysed for Sr concentration and Sr isotopes. RESULTS: Using ICP-MS/MS we show for the first time that internal mass bias correction of 87 Sr16 O/86 Sr16 O based on 88 Sr16 O/86 Sr16 O works to give for NIST SRM 987 a 87 Sr/86 Sr ratio of 0.7101 ± 0.012 (RSD = 0.17%) and for NIST SRM 1570a a 87 Sr/86 Sr ratio of 0.7100 ± 0.009 (RSD = 0.12%), which are within error of the accepted values. The first 87 Sr/86 Sr ratio of NIST SRM 1547 is 0.7596 ± 0.0014. Strontium analyses were run on 0.8 mL of 0.25-0.5 ppb Sr, which equates to 2-4 ng of Sr. Strontium isotope analysis with a precision of >99.8% can be achieved with in-line separation of 87 Sr from 87 Rb at least up to solutions with 25 ppb Rb. CONCLUSIONS: A minimum of 5 mg of insect tissue is required for Sr isotope analysis. This new ICP-MS/MS method enables Sr isotope analysis in single insects, allowing population-scale studies to be feasible and making possible applications with time-critical uses such as biosecurity.


Assuntos
Insetos/química , Isótopos de Estrôncio/análise , Espectrometria de Massas em Tandem/métodos , Animais , Gases , Limite de Detecção , Óxido Nitroso/química , Queensland , Radioisótopos de Rubídio/análise
9.
Nanotechnology ; 31(19): 195602, 2020 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31931487

RESUMO

All-dielectric photonics is a rapidly developing field of optics and material science. The main interest at visible and near-infrared frequencies is light management using high-refractive-index Mie-resonant dielectric particles. Most work in this area of research focuses on exploiting Si-based particles. Here, we study monocrystalline Mie-resonant particles made of Ge-rich SiGe alloys with refractive index higher than that of Si. These islands are formed via solid state dewetting of SiGe flat layers by using two different processes: (i) dewetting of monocrystalline SiGe layers (60%-80% Ge content) obtained via Ge condensation of SiGe on silicon on insulator; and (ii) dewetting of a SiGe layer deposited via molecular beam epitaxy on silicon on insulator and ex situ Ge condensation, forming a Ge-rich shell surrounding a SiGe-core. Using high-spatial-resolution Raman microscopy we monitor Ge content x and strain ϵ of flat layers and SiGe-islands. We observe strain relaxation associated with formation of trading dislocations in the SiGe islands compared to the starting SiGe layers, as confirmed by TEM images. For initial high Ge concentration in the flat layers, the corresponding Ge content in the dewetted islands is lower, owing to diffusion of Si atoms from Si or SiO2 into SiGe islands. The Ge content also varies from particle to particle on the same sample. Size and shape of the dewetted particles depend on the fabrication process: thicker initial SiGe layers lead to larger particles. Samples with narrow island size distribution display rather sharp Mie resonances in the 1000-2500 nm spectral range. Larger islands display Mie resonances at longer wavelength. Positions of the resonances are in agreement with the theoretical calculations in the discrete dipole approximation.

10.
Environ Sci Technol ; 52(16): 9391-9402, 2018 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-29952204

RESUMO

Concerns regarding the impact of neonicotinoid exposure on bee populations recently led to an EU-wide moratorium on the use of certain neonicotinoids on flowering crops. Currently, evidence regarding the impact, if any, the moratorium has had on bees' exposure is limited. We sampled pollen and nectar from bumblebee colonies in rural and peri-urban habitats in three U.K. regions: Stirlingshire, Hertfordshire, and Sussex. Colonies were sampled over three years: prior to the ban (2013), during the initial implementation when some seed-treated winter-sown oilseed rape was still grown (2014), and following the ban (2015). To compare species-level differences, in 2014 only, honeybee colonies in rural habitats were also sampled. Over half of all samples were found to be contaminated ( n = 408), with thiamethoxam being the compound detected at the highest concentrations in honeybee- (up to 2.29 ng/g in nectar in 2014, median ≤ 0.1 ng/g, n = 79) and bumblebee-collected pollen and nectar (up to 38.77 ng/g in pollen in 2013, median ≤ 0.12 ng/g, n = 76). Honeybees were exposed to higher concentrations of neonicotinoids than bumblebees in 2014. While neonicotinoid exposure for rural bumblebees declined post-ban (2015), suggesting a positive impact of the moratorium, the risk of neonicotinoid exposure for bumblebees in peri-urban habitats remained largely the same between 2013 and 2015.


Assuntos
Inseticidas , Néctar de Plantas , Animais , Abelhas , Produtos Agrícolas , Neonicotinoides , Pólen , Tiametoxam
12.
Nano Lett ; 17(12): 7299-7305, 2017 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-29116815

RESUMO

Selective oxidation of the silicon element of silicon germanium (SiGe) alloys during thermal oxidation is a very important and technologically relevant mechanism used to fabricate a variety of microelectronic devices. We develop here a simple integrative approach involving vapor-liquid-solid (VLS) growth followed by selective oxidation steps to the construction of core-shell nanowires and higher-level ordered systems with scalable configurations. We examine the selective oxidation/condensation process under nonequilibrium conditions that gives rise to spontaneous formation of core-shell structures by germanium condensation. We contrast this strategy that uses reaction-diffusion-segregation mechanisms to produce coherently strained structures with highly configurable geometry and abrupt interfaces with growth-based processes which lead to low strained systems with nonuniform composition, three-dimensional morphology, and broad core-shell interface. We specially focus on SiGe core-shell nanowires and demonstrate that they can have up to 70% Ge-rich shell and 2% homogeneous strain with core diameter as small as 14 nm. Key elements of the building process associated with this approach are identified with regard to existing theoretical models. Moreover, starting from results of ab initio calculations, we discuss the electronic structure of these novel nanostructures as well as their wide potential for advanced device applications.

13.
Am J Addict ; 26(7): 722-730, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28836711

RESUMO

BACKGROUND AND OBJECTIVES: Alcohol withdrawal-especially delirium tremens (DT)-is a potentially life-threatening condition. While short-term treatment regimens and factors that predispose to more severe symptomatology have been extensively studied, little attention has been paid to the clinical epidemiology and long-term care of the chronic medical, addictive, psychiatric, and psychosocial problems faced by these patients. METHODS: National Veterans Health Administration data from fiscal year 2012 were examined to identify veterans diagnosed with DT; with withdrawal but not DT (WNDT); and with Alcohol Use Disorder (AUD) but neither DT nor WNDT. They were compared on sociodemographic characteristics, psychiatric and medical co-morbidities, and health service and psychotropic medication use, first with bivariate analyses and then multiple logistic regression. RESULTS: Among the 345,297 veterans diagnosed with AUD, 2,341 (0.7%) were diagnosed with DT and 6,738 (2.0%) with WNDT. Veterans diagnosed with either WNDT or DT were more likely to have been homeless, had more comorbid medical and psychiatric disorders, were more likely to be diagnosed with drug use disorders, utilized more health services, received more psychotropic medications, and were more likely to receive naltrexone. They were more likely to receive specialized legal, housing, vocational, and psychosocial rehabilitation services, as well as intensive case management. CONCLUSIONS: Adults with WNDT and DT suffer from multiple chronic conditions and long-term service models are needed to coordinate the work of multiple specialists and to assure continuity of care. SCIENTIFIC SIGNIFICANCE: This national study identifies sociodemographic characteristics, comorbidities, and service utilization patterns associated with WNDT and DT.(Am J Addict 2017;26:722-730).


Assuntos
Delirium por Abstinência Alcoólica , Alcoolismo , Múltiplas Afecções Crônicas , Veteranos , Adulto , Idoso , Delirium por Abstinência Alcoólica/diagnóstico , Delirium por Abstinência Alcoólica/epidemiologia , Delirium por Abstinência Alcoólica/etiologia , Delirium por Abstinência Alcoólica/prevenção & controle , Alcoolismo/complicações , Alcoolismo/epidemiologia , Feminino , Pessoas Mal Alojadas/psicologia , Pessoas Mal Alojadas/estatística & dados numéricos , Humanos , Assistência de Longa Duração/métodos , Assistência de Longa Duração/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Múltiplas Afecções Crônicas/epidemiologia , Múltiplas Afecções Crônicas/terapia , Avaliação das Necessidades , Estados Unidos/epidemiologia , Veteranos/psicologia , Veteranos/estatística & dados numéricos , Saúde dos Veteranos/estatística & dados numéricos
15.
Small ; 12(44): 6115-6123, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27717242

RESUMO

Thin film dewetting can be efficiently exploited for the implementation of functionalized surfaces over very large scales. Although the formation of sub-micrometer sized crystals via solid-state dewetting represents a viable method for the fabrication of quantum dots and optical meta-surfaces, there are several limitations related to the intrinsic features of dewetting in a crystalline medium. Disordered spatial organization, size, and shape fluctuations are relevant issues not properly addressed so far. This study reports on the deterministic nucleation and precise positioning of Si- and SiGe-based nanocrystals by templated solid-state dewetting of thin silicon films. The dewetting dynamics is guided by pattern size and shape taking full control over number, size, shape, and relative position of the particles (islands dimensions and relative distances are in the hundreds nm range and fluctuate ≈11% for the volumes and ≈5% for the positioning).

16.
Nanotechnology ; 27(30): 305602, 2016 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-27302611

RESUMO

We report on a novel method for the implementation of core-shell SiGe-based nanocrystals combining silicon on insulator dewetting in a molecular beam epitaxy reactor with an ex situ Ge condensation process. With an in situ two-step process (annealing and Ge deposition) we produce two families of islands on the same sample: Si-rich, formed during the first step and, all around them, Ge-rich formed after Ge deposition. By increasing the amount of Ge deposited on the annealed samples from 0 to 18 monolayers, the islands' shape in the Si-rich zones can be tuned from elongated and flat to more symmetric and with a larger vertical aspect ratio. At the same time, the spatial extension of the Ge-rich zones is progressively increased as well as the Ge content in the islands. Further processing by ex situ rapid thermal oxidation results in the formation of a core-shell composition profile in both Si and Ge-rich zones with atomically sharp heterointerfaces. The Ge condensation induces a Ge enrichment of the islands' shell of up to 50% while keeping a pure Si core in the Si-rich zones and a ∼25% SiGe alloy in the Ge-rich ones. The large lattice mismatch between core and shell, the absence of dislocations and the islands' monocrystalline nature render this novel class of nanostructures a promising device platform for strain-based band-gap engineering. Finally, this method can be used for the implementation of ultralarge scale meta-surfaces with dielectric Mie resonators for light manipulation at the nanoscale.

17.
Sensors (Basel) ; 16(12)2016 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-27999245

RESUMO

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

18.
J Sports Sci ; 33(3): 293-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25105558

RESUMO

Good sleep is critical for optimising recovery and athletic performance. Yet, few studies have investigated how athletes sleep before and during competition. The aim of this study was to determine whether such sleep is poorer than that before a usual training day. Twenty-one male endurance cyclists' (age: 19.9 ± 1.7 years) sleep/wake behaviour was assessed using wrist activity monitors for 11 nights, including a six-night baseline training phase, three nights before competition and two nights during competition. Cyclists had less sleep on the night before competition (6.5 ± 0.9 h) and during the first night of competition (6.8 ± 0.8 h) than at baseline (7.4 ± 0.6 h). Cyclists also went to bed and woke up earlier during competition than at baseline. Competition schedules and competition itself can disrupt the sleep/wake behaviour of athletes during competition. Future investigations should examine sleep during three stages of competition (i.e. before, during and after competition). This will help coaches develop a greater understanding of how sleep changes during different phases of competition and enable them to plan post-competition training programmes to ensure appropriate rest and recovery is obtained.


Assuntos
Ciclismo/fisiologia , Comportamento Competitivo/fisiologia , Resistência Física/fisiologia , Sono , Vigília , Actigrafia , Adolescente , Adulto , Humanos , Masculino , Educação Física e Treinamento , Adulto Jovem
19.
Clin Ophthalmol ; 18: 69-78, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38223817

RESUMO

Purpose: We evaluate visual outcomes in patients with EVO/EVO+™ (posterior chamber phakic intraocular lens with a central port) within approved United States (US) age and refractive range indications. Patients and Methods: This single-center retrospective study evaluated one-month, single-center postoperative data for 225 eyes meeting inclusion criteria and undergoing EVO/EVO+ implantation from April to October 2022. Data included lens size (mm), lens power (diopters of spherical and cylindrical power), preoperative best corrected visual acuity, preoperative spherical equivalent from manifest refraction, achieved postoperative uncorrected visual acuity, postoperative refraction, intraocular pressure (mmHg), and adverse events. Results: A total of 225 eyes underwent EVO/EVO+ Implantable Collamer Lens (ICL) implantation from April to October 2022, with 51.5% receiving toric lenses. The most common ICL size was 12.6mm (56.4%), followed by 13.2mm (27.5%), 12.1mm (15.1%), and 13.7mm (0.9%). Among patients with preoperative BCVA of 20/20 or better (149 eyes), 95.2% achieved postoperative UCVA of 20/20 or better, and 99.3% achieved UCVA of 20/25 or better at postoperative month one. About 75% of eyes were within a spherical equivalent target of ±0.50 D and 94% within ±1.00 D. Toric ICLs were implanted in 116 eyes (51.8%). Of these, anticipated residual cylinder >1 diopter was seen in 21 eyes (18.1%) resulting in three rotations, three explants, and three laser vision correction (LVC) enhancements. The postoperative adjustment rate (including rotations, exchanges, and LVC enhancement) was minimal (4.8%). Incidence of major adverse events was 0%. Conclusion: Our study, the largest US single-center analysis of EVO/EVO+ ICL implantation, demonstrates strong early results and infrequent adverse events, supporting ICL safety and effectiveness. High predictability and favorable visual outcomes, including 20/20 or better, highlight the reliability of this technology. Despite study limitations, our findings underscore this technology's effectiveness. Future research should refine patient criteria and assess long-term outcomes in this evolving landscape.

20.
J Hepatocell Carcinoma ; 11: 595-606, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38525156

RESUMO

Background and Aims: Limited methods exist to accurately characterize the risk of malignant progression of liver lesions. Enhancement pattern mapping (EPM) measures voxel-based root mean square deviation (RMSD) of parenchyma and the contrast-to-noise (CNR) ratio enhances in malignant lesions. This study investigates the utilization of EPM to differentiate between HCC versus cirrhotic parenchyma with and without benign lesions. Methods: Patients with cirrhosis undergoing MRI surveillance were studied prospectively. Cases (n=48) were defined as patients with LI-RADS 3 and 4 lesions who developed HCC during surveillance. Controls (n=99) were patients with and without LI-RADS 3 and 4 lesions who did not develop HCC. Manual and automated EPM signals of liver parenchyma between cases and controls were quantitatively validated on an independent patient set using cross validation with manual methods avoiding parenchyma with artifacts or blood vessels. Results: With manual EPM, RMSD of 0.37 was identified as a cutoff for distinguishing lesions that progress to HCC from background parenchyma with and without lesions on pre-diagnostic scans (median time interval 6.8 months) with an area under the curve (AUC) of 0.83 (CI: 0.73-0.94) and a sensitivity, specificity, and accuracy of 0.65, 0.97, and 0.89, respectively. At the time of diagnostic scans, a sensitivity, specificity, and accuracy of 0.79, 0.93, and 0.88 were achieved with manual EPM with an AUC of 0.89 (CI: 0.82-0.96). EPM RMSD signals of background parenchyma that did not progress to HCC in cases and controls were similar (case EPM: 0.22 ± 0.08, control EPM: 0.22 ± 0.09, p=0.8). Automated EPM produced similar quantitative results and performance. Conclusion: With manual EPM, a cutoff of 0.37 identifies quantifiable differences between HCC cases and controls approximately six months prior to diagnosis of HCC with an accuracy of 89%.


Current surveillance and diagnostic methods in hepatocellular carcinoma are suboptimal. Enhancement pattern mapping is an imaging technique that quantifies lesion signals and may be useful in diagnostic and surveillance methods. Enhancement pattern mapping describes quantifiable differences between malignant and benign liver tissue on contrast-enhanced MRI. It amplifies lesion signal and distinguishes malignancy in a surveillance population. The novel imaging technique was investigated at single institution and analyzed lesions compared to cirrhotic parenchyma. Future efforts will include further risk stratification across LI-RADS group categories. The results provide evidence that enhancement pattern mapping uses available imaging data to distinguish hepatocellular carcinoma from non-cancerous parenchyma with and without benign lesions on scans six months prior to diagnosis with standard MRI. The technique introduces a prospective modality to improve diagnostic accuracy and early detection with the goal of improving clinical outcomes.

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