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2.
Nature ; 580(7804): 478-482, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32322080

RESUMO

Ultrathin ferroelectric materials could potentially enable low-power perovskite ferroelectric tetragonality logic and nonvolatile memories1,2. As ferroelectric materials are made thinner, however, the ferroelectricity is usually suppressed. Size effects in ferroelectrics have been thoroughly investigated in perovskite oxides-the archetypal ferroelectric system3. Perovskites, however, have so far proved unsuitable for thickness scaling and integration with modern semiconductor processes4. Here we report ferroelectricity in ultrathin doped hafnium oxide (HfO2), a fluorite-structure oxide grown by atomic layer deposition on silicon. We demonstrate the persistence of inversion symmetry breaking and spontaneous, switchable polarization down to a thickness of one nanometre. Our results indicate not only the absence of a ferroelectric critical thickness but also enhanced polar distortions as film thickness is reduced, unlike in perovskite ferroelectrics. This approach to enhancing ferroelectricity in ultrathin layers could provide a route towards polarization-driven memories and ferroelectric-based advanced transistors. This work shifts the search for the fundamental limits of ferroelectricity to simpler transition-metal oxide systems-that is, from perovskite-derived complex oxides to fluorite-structure binary oxides-in which 'reverse' size effects counterintuitively stabilize polar symmetry in the ultrathin regime.

3.
ACS Nano ; 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-32003564

RESUMO

Layered transition metal dichalcogenides offer many attractive features for next-generation low-dimensional device geometries. Due to the practical and fabrication challenges related to in situ methods, the atomistic dynamics that give rise to realizable macroscopic device properties are often unclear. In this study, in situ transmission electron microscopy techniques are utilized in order to understand the structural dynamics at play, especially at interfaces and defects, in the prototypical film of monolayer MoS2 under electrical bias. Through our sample fabrication process, we clearly identify the presence of mass transport in the presence of a lateral electric field. In particular, we observe that the voids present at grain boundaries combine to induce structural deformation. The electric field mediates a net vacancy flux from the grain boundary interior to the exposed surface edge sites that leaves molybdenum clusters in its wake. Following the initial biasing cycles, however, the mass flow is largely diminished and the resultant structure remains stable over repeated biasing. We believe insights from this work can help explain observations of nonuniform heating and preferential oxidation at grain boundary sites in these materials.

4.
Nat Commun ; 10(1): 4948, 2019 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-31666515

RESUMO

Currently, there is considerable interest in developing advanced rechargeable batteries that boast efficient distribution of electricity and economic feasibility for use in large-scale energy storage systems. Rechargeable aqueous zinc batteries are promising alternatives to lithium-ion batteries in terms of rate performance, cost, and safety. In this investigation, we employ Cu3(HHTP)2, a two-dimensional (2D) conductive metal-organic framework (MOF) with large one-dimensional channels, as a zinc battery cathode. Owing to its unique structure, hydrated Zn2+ ions which are inserted directly into the host structure, Cu3(HHTP)2, allow high diffusion rate and low interfacial resistance which enable the Cu3(HHTP)2 cathode to follow the intercalation pseudocapacitance mechanism. Cu3(HHTP)2 exhibits a high reversible capacity of 228 mAh g-1 at 50 mA g-1. At a high current density of 4000 mA g-1 (~18 C), 75.0% of the initial capacity is maintained after 500 cycles. These results provide key insights into high-performance, 2D conductive MOF designs for battery electrodes.

5.
J Am Chem Soc ; 141(43): 17421-17430, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31589035

RESUMO

Semiconductors possessing both magnetic and optoelectronic properties are rare and promise applications in opto-spintronics. Here we report the mixed-anion semiconductor BaFMn0.5Te with a band gap of 1.76 eV and a work function of 5.08 eV, harboring both antiferromagnetism (AFM) and strong red photoluminescence (PL). The synthesis of BaFMn0.5Te in quantitative yield was accomplished using the "panoramic synthesis" technique and synchrotron radiation to obtain the full reaction map, from which we determined that the compound forms upon heating at 850 °C via an intermediate unknown phase. The structure refinement required the use of a (3+1)-dimensional superspace group Cmme(α01/2)0ss. The material crystallizes into a ZrCuSiAs-like structure with alternating [BaF]+ and [Mn0.5Te]- layers and has a commensurately modulated structure with the q-vector of 1/6a* + 1/6b* + 1/2c* at room temperature arising from the unique ordering pattern of Mn2+ cations. Long-range AFM order emerges below 90 K, with two-dimensional short-range AFM correlations above the transition temperature. First-principles calculations indicate that BaFMn0.5Te is an indirect band gap semiconductor with the gap opening between Te 5p and Mn 3d orbitals, and the magnetic interactions between nearest-neighbor Mn2+ atoms are antiferromagnetic. Steady-state PL spectra show a broad strong emission centered at ∼700 nm, which we believe originates from the energy manifolds of the modulated Mn2+ sublattice and its defects. Time-resolved PL measurements reveal an increase in excited-state lifetimes with longer probe wavelengths, from 93 ns (at 650 nm) to 345 ns (at 800 nm), and a delayed growth (6.5 ± 0.3 ns) in the kinetics at 800 nm with a concomitant decay (4.1 ± 0.1 ns) at 675 nm. Together, these observations suggest that there are multiple emissive states, with higher energy states populating lower energy states by energy transfer.

6.
J Am Chem Soc ; 141(33): 13028-13032, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31386354

RESUMO

The self-assembly of nanoparticles, a process whereby nanocrystal building blocks organize into even more ordered superstructures, is of great interest to nanoscience. Here we report the layer-by-layer assembly of 2D perovskite nanosheet building blocks. Structural analysis reveals that the assembled superlattice nanocrystals match with the layered Ruddlesden-Popper perovskite phase. This assembly proves reversible, as these superlattice nanocrystals can be reversibly exfoliated back into their building blocks via sonication. This study demonstrates the opportunity to further understand and exploit thermodynamics to increase order in a system of nanoparticles and to study emergent optical properties of a superlattice from 2D, weakly attracted, perovskite building blocks.

7.
JAMA Netw Open ; 2(4): e192036, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30977852

RESUMO

Importance: Despite its spread in much of the United States and increased international interest, the Physician Orders for Life-Sustaining Treatment (POLST) paradigm still lacks supporting evidence. The interrater reliability of the POLST form to translate patients' values and preferences into medical orders for care at the end of life remains to be studied. Objective: To assess the interrater reliability of the medical orders documented in POLST forms. Design, Setting, and Participants: This cross-sectional study was conducted in a public university hospital in southeastern Brazil. Two independent researchers interviewed the same patients or decision-making surrogates (n = 64) during a single episode of hospitalization within a time frame of 1 to 7 days. Eligible participants were hospitalized adults aged 21 years or older who were expected to remain hospitalized for at least 4 days and whose attending physician responded no to the question, Would I be surprised if this patient died in the next year? Data collection occurred between November 1, 2015, and September 20, 2016, and first data analyses were performed on October 3, 2016. Main Outcomes and Measures: Interrater reliability as measured by κ statistics. Results: Of the 64 participants interviewed in the study, 53 (83%) were patients and 11 (17%) were surrogates. Patients' mean (SD) age was 64 (14) years, and 35 patients (55%) and 8 surrogates (73%) were women. Overall, in 5 cases (8%), disagreement in at least 1 medical order for life-sustaining treatment was found in the POLST form, changing from the first interview to the second interview. The κ statistic for cardiopulmonary resuscitation was 0.92 (95% CI, 0.80-1.00); for level of medical intervention, 0.89 (95% CI, 0.76-1.00); and for artificially administered nutrition, 0.92 (95% CI, 0.83-1.00). Conclusions and Relevance: The high interrater reliability of the medical orders in POLST forms appears to offer further support for this advance care planning paradigm; in addition, the finding that this interrater reliability was not 100% underscores the need to ensure that patients or their surrogates have decision-making capacity and to confirm that the content of POLST forms accurately reflects patients' current treatment preferences.


Assuntos
Planejamento Antecipado de Cuidados/normas , Atitude Frente a Morte , Cuidados para Prolongar a Vida/psicologia , Preferência do Paciente/psicologia , Assistência Terminal/normas , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil , Estudos Transversais , Tomada de Decisões , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Médicos/psicologia , Reprodutibilidade dos Testes , Assistência Terminal/psicologia , Traduções
8.
Adv Mater ; 31(24): e1808244, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31034105

RESUMO

Lateral heterogeneities in atomically thin 2D materials such as in-plane heterojunctions and grain boundaries (GBs) provide an extrinsic knob for manipulating the properties of nano- and optoelectronic devices and harvesting novel functionalities. However, these heterogeneities have the potential to adversely affect the performance and reliability of the 2D devices through the formation of nanoscopic hot-spots. In this report, scanning thermal microscopy (SThM) is utilized to map the spatial distribution of the temperature rise within monolayer transition metal dichalcogenide (TMD) devices upon dissipating a high electrical power through a lateral interface. The results directly demonstrate that lateral heterojunctions between MoS2 and WS2 do not largely impact the distribution of heat dissipation, while GBs of MoS2 appreciably localize heating in the device. High-resolution scanning transmission electron microscopy reveals that the atomic structure is nearly flawless around heterojunctions but can be quite defective near GBs. The results suggest that the interfacial atomic structure plays a crucial role in enabling uniform charge transport without inducing localized heating. Establishing such structure-property-processing correlation provides a better understanding of lateral heterogeneities in 2D TMD systems which is crucial in the design of future all-2D electronic circuitry with enhanced functionalities, lifetime, and performance.

10.
ACS Appl Mater Interfaces ; 10(8): 7239-7247, 2018 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-29388422

RESUMO

In this work, we have synthesized Cd1-xGaxO1+δ alloy thin films at room temperature over the entire composition range by radio frequency magnetron sputtering. We found that alloy films with high Ga contents of x > 0.3 are amorphous. Amorphous Cd1-xGaxO1+δ alloys in the composition range of 0.3 < x < 0.5 exhibit a high electron mobility of 10-20 cm2 V-1 s-1 with a resistivity in the range of 10-2 to high 10-4 Ω cm range. The resistivity of the amorphous alloys can also be controlled over 5 orders of magnitude from 7 × 10-4 to 77 Ω cm by controlling the oxygen stoichiometry. Over the entire composition range, these crystalline and amorphous alloys have a large tunable intrinsic band gap range of 2.2-4.8 eV as well as a conduction band minimum range of 5.8-4.5 eV below the vacuum level. Our results suggest that amorphous Cd1-xGaxO1+δ alloy films with 0.3 < x < 0.4 have favorable optoelectronic properties as transparent conductors on flexible and/or organic substrates, whereas the band edges and electrical conductivity of films with 0.3 < x < 0.7 can be manipulated for transparent thin-film transistors as well as electron transport layers.

11.
Medicine (Baltimore) ; 96(42): e7861, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29049185

RESUMO

Essential hypertension (EH) is a complex disease in which physiological, environmental, and genetic factors are involved in its genesis. The genetic variant of the alpha-adducin gene (ADD1) has been described as a risk factor for EH, but with controversial results.The objective of this study was to evaluate the association of ADD1 (Gly460Trp) gene polymorphism with the EH risk in a population from Madeira Island.A case-control study with 1614 individuals of Caucasian origin was performed, including 817 individuals with EH and 797 controls. Cases and controls were matched for sex and age, by frequency-matching method. All participants collected blood for biochemical and genotypic analysis for the Gly460Trp polymorphism. We further investigated which variables were independently associated to EH, and, consequently, analyzed their interactions.In our study, we found a significant association between the ADD1 gene polymorphism and EH (odds ratio 2.484, P = .01). This association remained statistically significant after the multivariate analysis (odds ratio 2.548, P = .02).The ADD1 Gly460Trp gene polymorphism is significantly and independently associated with EH risk in our population. The knowledge of genetic polymorphisms associated with EH is of paramount importance because it leads to a better understanding of the etiology and pathophysiology of this pathology.


Assuntos
Proteínas de Ligação a Calmodulina/genética , Grupo com Ancestrais do Continente Europeu/genética , Predisposição Genética para Doença/etnologia , Hipertensão/genética , Polimorfismo Genético , Adulto , Estudos de Casos e Controles , Hipertensão Essencial , Feminino , Humanos , Hipertensão/etnologia , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Portugal/etnologia , Fatores de Risco
13.
Genet Test Mol Biomarkers ; 21(10): 625-631, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28872890

RESUMO

AIMS: Essential hypertension (EH) is a disease in which both environment and genes have an important role. This study was designed to identify the interaction model between genetic variants and environmental risk factors that most highly potentiates EH development. METHODS: We performed a case-control study with 1641 participants (mean age 50.6 ± 8.1 years), specifically 848 patients with EH and 793 controls, adjusted for gender and age. Traditional risk factors, biochemical and genetic parameters, including the genotypic discrimination of 14 genetic variants previously associated with EH, were investigated. Multifactorial dimensionality reduction (MDR) software was used to analyze gene-environment interactions. Validation was performed using logistic regression analysis with environmental risk factors, significant genetic variants, and the best MDR model. RESULTS: The best model indicates that the interactions among the ADD1 rs4961 640T allele, diabetes, and obesity (body mass index ≥30) increase approximately four-fold the risk of EH (odds ratio = 3.725; 95% confidence interval: 2.945-4.711; p < 0.0001). CONCLUSION: This work showed that the interaction between the ADD1 rs4961 variant, obesity, and the presence of diabetes increased the susceptibility to EH four-fold. In these circumstances, lifestyle adjustment and diabetes control should be intensified in patients who carry the ADD1 variant.


Assuntos
Hipertensão Essencial/etiologia , Hipertensão Essencial/genética , Interação Gene-Ambiente , Adulto , Estudos de Casos e Controles , Complicações do Diabetes , Hipertensão Essencial/metabolismo , Feminino , Predisposição Genética para Doença/genética , Variação Genética/genética , Humanos , Hipertensão/genética , Masculino , Pessoa de Meia-Idade , Redução Dimensional com Múltiplos Fatores/métodos , Obesidade/complicações , Polimorfismo de Nucleotídeo Único/genética , Portugal , Fatores de Risco , Proteína de Ligação a Elemento Regulador de Esterol 1/genética , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo
14.
Iran J Kidney Dis ; 11(4): 303-308, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28794293

RESUMO

INTRODUCTION: Pulmonary hypertension (PH) has been reported in hemodialysis patients, but data regarding its pathogenesis are scarce. This study aimed to evaluate the role of fluid overload in PH and its interrelationships with the usual biomarkers of micro-inflammatory state in hemodialysis patients. MATERIALS AND METHODS: In is a cross-sectional and prospective study, 119 consecutive hemodialysis patients at a Brazilian referral university hospital were evaluated between March 2007 and February 2013. Based on the presence of echocardiographic parameters of PH, patients were allocated to two groups of the PH group and the non-PH group. Clinical parameters, site and type of vascular access, bio-impedance, and laboratory findings were compared between the two groups and a logistic regression model was elaborated. RESULTS: Pulmonary hypertension was found in 23 (19.0%) of 119 patients. The groups significantly differed in extracellular water, ventricular thickness, left atrium diameter, and ventricular filling. Additionally, laboratory data associated with PH were alpha-1-acid glycoprotein (140.0 ± 32.9 versus 116.0 ± 35.5; P < .001); C-reactive protein (median, 1.1 versus 1.6; P = .01) and B-type natriuretic peptide (median, 328 versus 77; P = .03). The adjusted logistic regression model, including alpha-1-acid glycoprotein and B-type natriuretic peptide, showed significant associations for both (odds ratio, 1.023; 95% confidence interval, 1.008 to 1.043;  P = .004 and odds ratio, 3.074; 95% confidence interval, 1.49-6.35; P = .002, respectively). CONCLUSIONS: Pulmonary hypertension, cardiac hypertrophy, fluid overload, and inflammation were associated to each other in hemodialysis patients, providing insight into its pathogenesis. Longitudinal studies are warranted.


Assuntos
Pressão Arterial , Hipertensão Pulmonar/etiologia , Mediadores da Inflamação/sangue , Inflamação/etiologia , Falência Renal Crônica/terapia , Artéria Pulmonar/fisiopatologia , Diálise Renal/efeitos adversos , Equilíbrio Hidroeletrolítico , Desequilíbrio Hidroeletrolítico/etiologia , Adulto , Idoso , Biomarcadores/sangue , Composição Corporal , Brasil , Cardiomegalia/etiologia , Distribuição de Qui-Quadrado , Estudos Transversais , Impedância Elétrica , Feminino , Hospitais Universitários , Humanos , Hipertensão Pulmonar/diagnóstico , Hipertensão Pulmonar/fisiopatologia , Inflamação/sangue , Inflamação/diagnóstico , Falência Renal Crônica/diagnóstico , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Estudos Prospectivos , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Desequilíbrio Hidroeletrolítico/diagnóstico , Desequilíbrio Hidroeletrolítico/fisiopatologia
15.
Int J Clin Pract ; 71(6)2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28503909

RESUMO

Several genetic risk scores (GRS) have been associated with cardiovascular disease; their role, however, in survival from proven coronary artery disease (CAD) have yielded conflicting results. OBJECTIVE: The objective of this study was to evaluate long-term cardiovascular mortality according to the genetic risk score in a Southern European population with CAD. METHODS: A cohort of 1464 CAD patients with angiographic proven CAD were followed up prospectively for up to 58.3 (interquartile range: 25.8-88.1) months. Genotyping of 32 single-nucleotide polymorphisms previously associated with CAD was performed using oligonucleotides probes marked with fluorescence for each allele. GRS was constructed according to the additive model assuming codominance and categorised using the median (=26). Cox Regression analysis was performed to determine independent multivariate predictors of cardiovascular mortality. Kaplan-Meier survival curves compared high vs low GRS using log-rank test. C-index was done for our population, as a measure of discrimination in survival analysis model. RESULTS: During a mean follow-up of 58.3 months, 156 patients (10.7%) died, 107 (7.3%) of CV causes. High GRS (≥26) was associated with reduced cardiovascular survival. Survival analysis with Cox regression model adjusted for 8 variables showed that high GRS, dyslipidemia, diabetes and 3-vessel disease were independent risk factors for cardiovascular mortality (HR=1.53, P=.037; HR=3.64, P=.012; HR=1.75, P=.004; HR=2.97, P<.0001, respectively). At the end of follow-up, the estimated survival probability was 70.8% for high GRS and 80.8% for low GRS (Log-rank test 5.6; P=.018). C-Index of 0.71 was found when GRS was added to a multivariate survival model of diabetes, dyslipidemia, smoking, hypertension and 3 vessel disease, stable angina and dual antiplatelet therapy. CONCLUSIONS: Besides the classical risk factors management, this work highlights the relevance of the genetic profile in survival from CAD. It is expected that new therapies will be dirsected to gene targets with proven value in cardiovascular survival.


Assuntos
Doença da Artéria Coronariana/genética , Doença da Artéria Coronariana/mortalidade , Idoso , Estudos de Coortes , Angiografia Coronária , Doença da Artéria Coronariana/complicações , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Portugal , Análise de Regressão , Fatores de Risco , Análise de Sobrevida
16.
Ultramicroscopy ; 183: 99-103, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28396081

RESUMO

The knowledge of the structural and electronic surface morphology is imperative to fully understand the charge transfer at interfaces of electronic devices, such as in photovoltaic (PV) cells. To this aim, here, we use low-energy electron microscopy to probe the unoccupied states of post-annealed MoOx thin-films grown in oxygen excess (x∼3.16) and deficient (x∼2.57) environments. 2D work function maps are correlated with the surface topography extracted by mirror electron microscopy (MEM) mode, which show homogenous surface morphology and electronic levels for the specimen with x∼2.57, while it demonstrates nanoaggregates with different work functions on top of flat surface areas for the sample grown with x∼3.16.

17.
Epilepsy Res ; 132: 100-108, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28376388

RESUMO

PURPOSE: Quantitative techniques of diffusion analysis allow for an in-vivo investigation of the physiopathology of epilepsies. The objective of this study was to evaluate the variation of the main diffusion parameters and explore differences between two methodologies of voxel-wise analysis comparing a group of patients with mesial temporal lobe epilepsy (MTLE) with controls. METHODS: 24 patients with a diagnosis of MTLE were selected. All patients and a control group of 36 individuals were submitted to 3T magnetic resonance imaging. Diffusion parameters were obtained from the raw images. Based on the tensors, a customized template was created, and images were registered into standard space. Voxel-based comparisons between patients and controls was performed by whole brain voxel-wise analysis and tract-based spatial statistics (TBSS). Tract-specific analysis (TSA) was performed in the mostly damaged fasciculi. RESULTS: 10 patients presented with right hippocampal sclerosis (HS), 11 with left HS and 3 with bilateral HS with left predominance. Whole brain voxel-wise analysis showed abnormalities mainly localized in the temporal lobes (total volume of 3859mm3). TBSS showed more widespread abnormalities (21931mm3). TSA pointed to abnormalities situated essentially in the temporal stem topography. Fractional anisotropy (FA) and radial diffusivity (RD) were the parameters that showed more abnormalities. CONCLUSION: Whole brain voxel-wise analysis was more restricted than TBSS. The methods were complementary stressing the significance of the findings. The abnormalities were more frequently observed in FA and RD indicating the need for using several diffusion parameters for the investigation of patients with MTLE.


Assuntos
Imagem de Tensor de Difusão , Epilepsia do Lobo Temporal/diagnóstico por imagem , Adulto , Idoso , Anisotropia , Imagem de Tensor de Difusão/métodos , Feminino , Hipocampo/diagnóstico por imagem , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imagem por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Esclerose/patologia , Lobo Temporal/diagnóstico por imagem , Substância Branca/patologia , Adulto Jovem
18.
ACS Appl Mater Interfaces ; 9(8): 7717-7724, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28165215

RESUMO

The ability to control the interfacial properties in metal-oxide thin films through surface defect engineering is vital to fine-tune their optoelectronic properties and thus their integration in novel optoelectronic devices. This is exemplified in photovoltaic devices based on organic, inorganic or hybrid technologies, where precise control of the charge transport properties through the interfacial layer is highly important for improving device performance. In this work, we study the effects of in situ annealing in nearly stoichiometric MoOx (x ∼ 3.0) thin-films deposited by reactive sputtering. We report on a work function increase of almost 2 eV after inducing in situ crystallization of the films at 500 °C, resulting in the formation of a single crystalline α-MoO3 overlaid by substoichiometric and highly disordered nanoaggregates. The surface nanoaggregates possess various electronic properties, such as a work function ranging from 5.5 eV up to 6.2 eV, as determined from low-energy electron microscopy studies. The crystalline underlayer possesses a work function greater than 6.3 eV, up to 6.9 eV, characteristic of a very clean and nearly defect-free MoO3. By combining electronic spectroscopies together with structural characterizations, this work addresses a novel method for tuning, and correlating, the optoelectronic properties and microstructure of device-relevant MoOx layers.

19.
Eur Heart J Cardiovasc Imaging ; 18(2): 119-127, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27679598

RESUMO

AIMS: Left atrial (LA) function index (LAFI) is a rhythm-independent index that combines LA emptying fraction (LAEF), adjusted LA volume (LAVi), and stroke volume. We evaluated LAFI as a predictor of long-term survival in outpatients with heart failure with reduced ejection fraction (HFrEF). METHODS AND RESULTS: For 3 years, we followed up 203 outpatients with a left ventricular ejection fraction <40%, who were clinically stable and on optimal therapy. The endpoint was all-cause death. LAFI was calculated as LAFI = ([LAEF × left ventricular outflow tract-velocity time integral]/[LAVi]), and was categorized into quartiles (9.26/16.56/31.92) and median (16.57). Incremental Cox regression models adjusted for significant confounders were used for survival analyses. The 3-year death rate was 30%. Higher quartiles had lower death rates (43.1%/45.1%/25.5%/6%, P < 0.001). The receiver operating characteristic curve for death was associated with LAFI (area under curve = 0.695, 95% CI 0.62-0.77, P < 0.001). In the direct comparison with LAVi and LAEF, LAFI (HRcox 0.93, 95% CI 0.89-0.97, P < 0.001) was the only predictor of survival. LAFI (HRcox 0.95, 95% CI 0.88-1.01, P = 0.099), LAFI quartiles (HR 0.29, 95% CI 0.125-0.672, P=0.004), and LAFI ≥16.57 (HRcox 0.62, 95% CI 0.38-1.02, P=0.058) were adjusted predictors of survival. Subgroup analysis by heart rhythm (sinus vs. atrial fibrillation) showed that LAFI per unit increase and LAFI quartiles were independent predictors of death in both subgroups. CONCLUSION: LAFI determination in HFrEF stable outpatients is a predictor of long-term survival and provides increased prognostic value over a wide range of confounder risk factors.


Assuntos
Fibrilação Atrial/epidemiologia , Função do Átrio Esquerdo/fisiologia , Insuficiência Cardíaca Sistólica/diagnóstico por imagem , Insuficiência Cardíaca Sistólica/mortalidade , Volume Sistólico/fisiologia , Idoso , Idoso de 80 Anos ou mais , Área Sob a Curva , Fibrilação Atrial/diagnóstico por imagem , Causas de Morte , Estudos de Coortes , Ecocardiografia/métodos , Eletrocardiografia/métodos , Feminino , Insuficiência Cardíaca Sistólica/tratamento farmacológico , Insuficiência Cardíaca Sistólica/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Modelos de Riscos Proporcionais , Curva ROC , Estudos Retrospectivos , Medição de Risco , Índice de Gravidade de Doença , Análise de Sobrevida
20.
Clin Hemorheol Microcirc ; 65(2): 185-194, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-27716652

RESUMO

BACKGROUND: RDW is an automatic value obtained with the blood count, and represents the erythrocytes dimension variation. OBJECTIVE: To evaluate in optimally medicated outpatients with heart failure with reduced ejection fraction (HFrEF) the RDW prognostic value regarding survival in a multivariable model including anemia and Nt-ProBNP. METHODS: 233 consecutive outpatients, LVEF <40%, clinically stable were followed-up for 3-years in an HF Unit. End-point was all-cause death. The RDW categorized according to the tertiles (T1 = <13.9; T2 14-15.2; T3> = 15.3). Anemia classified according to the WHO criteria. Cox survival model adjusted for clinical profile, optimal therapeutic, renal function, Nt-ProBNP, etiology, atrial fibrillation, and anemia. RESULTS: (1) The 3-years death rate was 33.5%, and increased with the RDW tertiles (17.3%; 25%; 61.1%; p < 0.001). (2) The ROC curve for death associated with RDW (AUC 0.73; p < 0.001); (3) The adjusted death risk increased with the tertiles (Hazard-ratio '[HR] = 1.61; IC 95% 1.09-2.39; p = 0.017). RDW> = 15.3 had greater adjusted death risk than T1 (HR = 2.18; 95% CI 0.99-4.8; p = 0.05) and T1+T2 (HR = 1.54; 95% CI 1.13-2.09; p = 0.006). CONCLUSION: RDW determined in optimally medicated outpatients with HFrEF, during dry-state, is a strong, cheap, and independent predictor of long-term survival.


Assuntos
Anemia/sangue , Insuficiência Cardíaca/sangue , Peptídeo Natriurético Encefálico/sangue , Fragmentos de Peptídeos/sangue , Volume Sistólico/fisiologia , Idoso , Índices de Eritrócitos , Feminino , Humanos , Masculino , Prognóstico
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