Effect of ZnO surface morphology on its electrochemical performance.

The purpose of this paper is to bridge the gap between ZnO surface morphology and its electrochemical performance. For this reason, ZnO nanowires (NWs) of different length were synthesized using an electrochemical method. Then, the electrochemical performance of the synthesized ZnO surfaces was studied using cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical analysis results revealed that the increase of ZnO NW length contributes to the retrogression of electrochemical performance. Indeed, the electrochemical performance is mainly related to the wettability behavior of the ZnO nanowire surfaces. When the ZnO NWs length increases, the surface become more hydrophobic, therefore, charge transfers between the electrode/electrolyte decrease. To improve the electrochemical performance of ZnO, we propose a new strategy combining NWs and microsheets (µSs) for further improving the morphology. Finally, the surfaces based on the double structure of ZnO provide good propagation of charge at the surface, good transfer in the electrode, good stability, and excellent scanning ability. In the present work we intend to pave the way for achieving high electrochemical performance ZnO-based layers.

Morphological, optical and photovoltaic characteristics of MoSe2/SiOx/Si heterojunctions.

This work reports the effect of different processing parameters on the structural and morphological characteristics of MoSe2 layers grown by chemical vapour deposition (CVD), using MoO3 and Se powders as solid precursors. It shows the strong dependence of the size, shape and thickness of the MoSe2 layers on the processing parameters. The morphology of the samples was investigated by field emission scanning electron microscopy (FESEM) and the thickness of the deposited layers was determined by atomic force microscopy (AFM). Raman and photoluminescence (PL) spectroscopies were used to confirm the high quality of the MoSe2 layers. Surface composition was examined by photoelectron spectroscopy (XPS). Moreover, the MoSe2/SiOx/Si heterojunctions exhibit diode behaviour, with a rectification ratio of 10, measured at ±2.0 V, which is due to the p-i-n heterojunctions formed at the p-Si/SiOx/MoSe2 interface. A photovoltaic effect was observed with a short circuit current density (Jsc), open circuit voltage (VOC) and efficiency of -0.80 mA/cm2, 1.55 V and 0.5%, respectively. These results provide a guide for the preparation of p-i-n heterojunctions based on few-layer MoSe2 with improved photovoltaic response.

Strain-Engineered Tetragonal Phase and Ferroelectricity in GdMnO3 Thin Films Grown on SrTiO3 (001).

A previously unreported tetragonal phase has been discovered in a epitaxially strained GdMnO3 thin films deposited on (001)-oriented SrTiO3 substrates by radio frequency (RF) magnetron sputtering. The tetragonal axis of the films grown up to a 35 nm thickness is perpendicular to the film surface and the basal lattice parameters are imposed by the cubic structure of the substrate. Furthermore, the emergence of a spontaneous electric polarization below ~32 K points to the stabilization of an improper ferroelectric phase at low temperatures, which is not observed in bulk GdMnO3. This work shows how strain engineering can be used to tailor the structure and properties of strongly correlated oxides.

Charge Coupling Enhanced Photocatalytic Activity of BaTiO3/MoO3 Heterostructures.

In this work, we proposed an efficient heterostructure photocatalyst by integrating the ferroelectric BaTiO3 (BTO) layer with the semiconductor MoO3 layer, availing the ferroelectric polarization of BaTiO3 and high generation of photoinduced charge carriers in the MoO3 layer. The effect of MoO3 layer thickness (tMoO3) on the photocatalytic efficiency of the BTO/MoO3 heterostructures is found to be optimum at tMoO3 = 67 nm as tMoO3 varies from 40 to 800 nm. The BTO/MoO3 heterostructure with tMoO3 = 67 nm exhibits a high efficiency of 86% for the degradation of rhodamine B (RhB) under the exposure of UV-visible light for 60 min. The photocatalysis rate kinetics analysis reveals that the rate constant in the heterostructure is 1.7 times of pure BTO and 3.2 times of pure MoO3 films. The enhanced photocatalytic activity in the heterostructures is attributed to the electric field-driven carrier separation due to the ferroelectric polarization and the heterojunction band bending. The charge coupling effect between BaTiO3 and MoO3 is evident from the current-voltage characteristics. The maximum lattice strain in the heterostructure with tMoO3 = 67 nm as evident from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL) analysis further confirms the charge transfer between the layers. The degradation as well as decolorization efficiency of the BTO/MoO3 heterostructure is higher than that of pure BTO and MoO3 films. Radical trapping experiments reveal that electrons are the major contributors to the photocatalytic activity of the BTO/MoO3 heterostructure. The reusability test shows only a reduction of 5% in the efficiency of the heterostructure after five photocatalysis cycles. The heterostructure can also efficiently decompose the other dyes such as rose bengal and methyl violet. Thus, our findings prove that an efficient and reusable photocatalyst can be designed through the integration of the ferroelectrics with the semiconductor layers.

High-Performance µ-Thermoelectric Device Based on Bi2Te3/Sb2Te3 p-n Junctions.

A flexible and ultralight planar thermoelectric generator based on 15 thermocouples composed of n-type bismuth telluride (Bi2Te3) and p-type antimony telluride (Sb2Te3) legs (each with 400 nm thick) connected in series, on 25 µm thick Kapton substrate, was fabricated with impressive power factor values of 2.7 and 0.8 mW K-2 m-1 (at 298 K) for Bi2Te3 and Sb2Te3 films, respectively. The p-n junction thermoelectric device can generate a maximum open-circuit voltage and output power of 210 mV and 0.7 µW (3.3 mW cm-2), respectively, for a temperature difference of 35 K, which is higher than the one observed for a conventional thermoelectric device with metallic contacts for p-n junctions. The results were combined with numerical simulations, showing a good match between the experimental and the numerical results. The current density versus voltage (J-V) characteristics of the fabricated p-n junctions revealed a diode behavior with a turn-on voltage of ≈0.3 V and an impressive rectifying ratio (I+1V/I-1V) of ≈2 × 104.

Highly sensitive thermoelectric touch sensor based on p-type SnO x thin film.

Here, the ability of using p-type tin oxide (SnO x ) thin films as a thermal sensor has been investigated. Firstly, the thermoelectric performance was optimized by controlling the thickness of the SnO x film from 60 up to 160 nm. A high Seebeck coefficient of +263 µV K-1 and electrical conductivity of 4.1 × 102 (S m-1) were achieved in a 60 nm thick SnO x film, due to a compact nanostructured film and the absence of the Sn metallic phase, which was observed for the thicker SnO x film leading to a typical thermoelectric transport properties of a n-type Sn film. Moreover, x-ray photoelectron spectroscopy revealed the co-existence of SnO (79.7%) and SnO2 (20.3%) phases in the 60 nm thick SnO x film, while the optical measurements revealed an indirect gap of 1.8 eV and a direct gap of 2.7 eV, respectively. The 60 nm-SnO x thin film have been tested as a thermoelectric touch sensor, achieving a Vsignal /Vnoise  ≈ 20, with a rise time <1 s. Therefore, this work provides an efficient way for developing highly efficient thermal sensors with potential use in display technologies.

Hysteretic Characteristics of Pulsed Laser Deposited 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3/ZnO Bilayers.

In the present work, we study the hysteretic behavior in the electric-field-dependent capacitance and the current characteristics of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BCZT)/ZnO bilayers deposited on 0.7 wt % Nb-doped (001)-SrTiO3 (Nb:STO) substrates in a metal-ferroelectric-semiconductor (MFS) configuration. The X-ray diffraction measurements show that the BCZT and ZnO layers are highly oriented along the c-axis and have a single perovskite and wurtzite phases, respectively, whereas high-resolution transmission electron microscopy revealed very sharp Nb:STO/BCZT/ZnO interfaces. The capacitance-electric field ( C- E) characteristics of the bilayers exhibit a memory window of 47 kV/cm and a capacitance decrease of 22%, at a negative bias. The later result is explained by the formation of a depletion region in the ZnO layer. Moreover, an unusual resistive switching (RS) behavior is observed in the BCZT films, where the RS ratio can be 500 times enhanced in the BCZT/ZnO bilayers. The RS enhancement can be understood by the barrier potential profile modulation at the depletion region, in the BCZT/ZnO junction, via ferroelectric polarization switching of the BCZT layer. This work builds a bridge between the hysteretic behavior observed either in the C- E and current-electric field characteristics on a MFS structure.

Enhanced resistive switching characteristics in Pt/BaTiO3/ITO structures through insertion of HfO2:Al2O3 (HAO) dielectric thin layer.

An enhanced resistive switching (RS) effect is observed in Pt/BaTiO3(BTO)/ITO ferroelectric structures when a thin HfO2:Al2O3 (HAO) dielectric layer is inserted between Pt and BTO. The P-E hysteresis loops reveal the ferroelectric nature of both Pt/BTO/ITO and Pt/HAO/BTO/ITO structures. The relation between the RS and the polarization reversal is investigated at various temperatures in the Pt/HAO/BTO/ITO structure. It is found that the polarization reversal induces a barrier variation in the Pt/HAO/BTO interface and causes enhanced RS, which is suppressed at Curie temperature (Tc = 140 °C). Furthermore, the Pt/HAO/BTO/ITO structures show promising endurance characteristics, with a RS ratio >103 after 109 switching cycles, that make them potential candidates for resistive switching memory devices. By combining ferroelectric and dielectric layers this work provides an efficient way for developing highly efficient ferroelectric-based RS memory devices.

Avaliação do impacto de laboratórios de análises clínicas de hospitais de urgência e emergência do município de Belém-PA na saúde / Health impact assessment of clinical analysis laboratories in Urgency and Emergency hospitals in Belém (PA, Brazil)

Este trabalho teve como objetivo avaliar o impacto de laboratórios de análises clínicas de hospitais de urgência e emergência do município de Belém-PA na saúde. Trata-se de um estudo do tipo descritivo com abordagem quantitativa, no qual os dados foram coletados por meio de entrevistas diretas por meio de um questionário contendo perguntas abertas e fechadas, seguindo uma ordem de questionamentos divididos em diferentes avaliações de impacto na saúde. Os resultados revelaram que os laboratórios de análises clínicas dos hospitais de urgência e emergência apresentam os serviços bem estruturados, com profissionais próprios qualificados e treinados periodicamente. Para a rotina laboratorial há documentos para guiar na operacionalização dos serviços, manuais de qualidade e credenciamento a programas e/ou empresas de certificação ou acreditação de qualidade. Os laboratórios realizam auditorias internas, apresentam dispositivo de medição quanto a ensaios e equipamentos calibrados, com manutenções periódicas e possuem responsáveis técnicos e diretores de laboratório. Quanto à citação do número de exames laboratoriais, o LAC A e o LAC D apresentam todos os exames hematológicos questionados, no entanto, o LAC B e LAC C apresentam 85,71% (n =12) dos exames questionados. Quando questionados em relação às dosagens bioquímicas, o LAC A e LAC D mostraram-se mais abrangentes por realizarem todos os exames bioquímicos propostos. Diante dos resultados obtidos, conclui-se que os laboratórios de urgência e/ou emergência existentes no município de Belém-PA oferecem ampla variedade de serviços, bem como apresentam preocupação com a garantia da qualidade da prestação de seus serviços...

This study is an assessment of the health impact of 4 clinical analysis laboratories (LAC A, B, C and D) in Urgency and Emergency hospitals in Belém (PA). In a descriptive study with a quantitative approach, we collected data through interviews conducted with a questionnaire containing open and closed questions, which were organized into various levels of health impact assessment. The results revealed that the clinical analysis laboratories of urgency and emergency hospitals have well-structured services, with qualified professionals who received periodic in service training. For routine lab work, there are well documented operational guidelines, quality manuals and programs and/or companies offering quality certification and accreditation. The laboratories make internal audits and possess measuring devices for assays and periodically calibrated equipment; they have responsible technicians and laboratory directors. In response to questions on the number of laboratory tests, LAC A and LAC D exhibited all the hematological tests cited, while LAC B and C showed 85.71% (n = 12) of the tests. Regarding the biochemical dosages, LAC A and LAC D proved to be more inclusive, covering all the recommended biochemical tests. On the basis of these results, we conclude that the clinical laboratories in urgency and/or emergency hospitals in Belém offer a wide variety of services, as well as showing concern for quality assurance in the provision of these services...

Desempenho produtivo, características de carcaça e avaliação econômica de bovinos cruzados, castrados e não-castrados, terminados em pastagens de Brachiaria decumbens / Productive performance, carcass characteristics and economic evaluation of castrated and non-castrated crossbred bovines finished in Brachiaria decumbens pastures

Avaliou-se o efeito da castração sobre o desempenho produtivo e sobre as características de carcaça e realizou-se a avaliação econômica de bovinos terminados em pastagens de Brachiaria decumbens. Foram utilizados oito novilhos Canchim-Nelore com 14 meses de idade, sendo quatro animais castrados e quatro não-castrados, com média de peso corporal de 273,2kg. O delineamento foi inteiramente ao acaso com quatro repetições por tratamento. Os animais receberam, diariamente, 0,7 por cento do PC de suplemento proteíco-energético e foram abatidos aos 26 meses de idade. O peso de abate e o ganho médio diário (GMD) diferiram entre castrados e não-castrados, com médias de 441,0 e 482,2kg e 0,6 e 0,7kg/dia, respectivamente. Não houve efeito da castração sobre as características avaliadas, com exceção do peso de abate, do peso da carcaça quente, 252,3 versus 229,9kg, da cor da carne, 3,25 versus 4,50 pontos e da espessura da gordura subcutânea, 0,6 versus 1,4mm, respectivamente, para não-castrados e castrados. A lucratividade por animal e por hectare foi de 14,5 e 15,8 por cento para não-castrados e 4,5 e 5,8 por cento para castrados, respectivamente. Sugere-se a utilização de bovinos não-castrados suplementados em pastagens de Brachiaria decumbens.

The effect of the castration on the productive performance and carcass characteristics was studied, as well as, the economic evaluation of finished bovines raised on Brachiaria decumbens pastures. Eight Canchim-Nellore steers aging 14-months-old were used, being four castrated and four non-castrated, averaging 273.2kg body weight. It was used a completely randomized design with four repetitions per treatment. The animals received 0.7 percent of their body weight of proteic-energetic supplement and were slaughtered at 26 months of age. The weight at slaughtering and the average daily weight gain differed between castrated and non-castrated, averaging 441.0 and 482.2kg, and 0.6 and 0.7kg/day, respectively. No effects of the castration on carcass characteristics were observed, except for weight of hot carcass, 252.3 versus 229.9kg; meat color, 3.25 versus 4.50 points; and subcutaneous fat thickness, 0.6 versus 1.4mm; respectively, for non-castrated and castrated. The profitabilities per animal and hectare were 14.5 and 15.8 percent for non-castrated and 4.5 percent and 5.8 percent for castrated, respectively. It is suggested the raised of non-castrated bovines supplemented on Brachiaria decumbens pastures.