Intrinsic electrochemical activity of single walled carbon nanotube–Nafion assemblies

The intrinsic electrochemical properties and activity of single walled carbon nanotube (SWNT) network electrodes modified by a drop-cast Nafion film have been determined using the one electron oxidation of ferrocene trimethyl ammonium (FcTMA+) as a model redox probe in the Nafion film. Facilitated by the very low transport coefficient of FcTMA+ in Nafion (apparent diffusion coefficient of 1.8 × 10−10 cm2 s−1), SWNTs in the 2-D network behave as individual elements, at short (practical) times, each with their own characteristic diffusion, independent of neighbouring sites, and the response is diagnostic of the proportion of SWNTs active in the composite. Data are analysed using candidate models for cases where: (i) electron transfer events only occur at discrete sites along the sidewall (with a defect density typical of chemical vapour deposition SWNTs); (ii) all of the SWNTs in a network are active. The first case predicts currents that are much smaller than seen experimentally, indicating that significant portions of SWNTs are active in the SWNT–Nafion composite. However, the predictions for a fully active SWNT result in higher currents than seen experimentally, indicating that a fraction of SWNTs are not connected and/or that not all SWNTs are wetted completely by the Nafion film to provide full access of the redox mediator to the SWNT surface

Uncompleted Emergency Department Care (UEDC): A 5-year population-based study in the Veneto Region, Italy

Introduction: Uncompleted visits to emergency departments (UEDC) are a patient safety concern. The purpose of this study was to investigate risk factors for UEDC, describing not only the sociodemographic characteristics of patients who left against medical advice (AMA) and those who left without being seen (LWBS), but also the characteristics of their access to the emergency department (ED) and of the hospital structure. Methods: This was a cross sectional study on anonymized administrative data in a population-based ED database. Results: A total of 9,147,415 patients attended EDs in the Veneto Region from 2011 to 2015. The UEDC rate was 28.7\u2030, with a slightly higher rate of AMA than of LWBS (15.3\u2030 vs 13.4\u2030). Age, sex, citizenship, and residence were sociodemographic factors associated with UEDC, and so were certain characteristics of access, such as mode of admission, type of referral, emergency level, waiting time before being seen, and type of medical issue (trauma or other). Some characteristics of the hospital structure, such as the type of hospital and the volume of patients managed, could also be associated with UEDC. Conclusion: Cases of UEDC, which may involve patients who leave AMA and those who LWBS, differ considerably from other cases managed at the ED. The present findings are important for the purpose of planning and staffing health services. Decision-makers should identify and target the factors associated with UEDC to minimize walkouts from public hospital EDs

Estimativas de parâmetros genéticos em linhagens de feijão-caupi de porte prostrado avaliadas em Aquidauana, MS.

Foram avaliados 20 genótipos de feijão-caupi, provenientes da Embrapa Meio-Norte, em relação a seis características morfo-agronômicas. O experimento foi conduzido na Universidade Estadual de Mato Grosso do Sul, Unidade de Aquidauana, no delineamento de blocos casualizados, com quatro repetições. As estimativas de parâmetros genéticos demonstraram situação favorável ao melhoramento por seleção da característica peso de cem grãos, que apresentou elevado valor de herdabilidade e valor de índice de variação superior à unidade

Adaptabilidade e estabilidade de linhagens de feijão-caupi de porte ereto em Mato Grosso do Sul.

Este trabalho teve como objetivo estudar a adaptabilidade e estabilidade de 20 genótipos de feijão-caupi provenientes da Embrapa Meio-Norte, em três municípios de Mato Grosso do Sul (Chapadão do Sul, Dourados e Aquidauana), com relação à produção de grãos (kg ha-1). Os experimentos foram conduzidos no delineamento de blocos ao acaso, com quatro repetições. Para identificação de genótipos com boa adaptabilidade e estabilidade em relação aos locais estudados, aplicou-se a metodologia de Eberhart & Russell (1966). A linhagem MNC00-553D-8-1-2-3 foi a mais promissora, podendo vir a ser recomendada para cultivo em Chapadão do Sul, Dourados e Aquidauana, com grande chance de sucesso na produção de grãos de feijão-caupi

Comportamento de genótipos de feijão-caupi de porte semi-ereto em ambientes de Mato Grosso do Sul.

Objetivando avaliar o comportamento produtivo de genótipos de feijão-caupi de porte semi-ereto em Mato Grosso do Sul (MS), conduziu-se o presente trabalho nos municípios de Chapadão do Sul, Dourados e Aquidauana. Os tratamentos consistiram de 17 linhagens e três cultivares delineados em blocos casualizados com quatro repetições. Dados de peso de cem grãos (PCG) e produção de grãos secos (PGS) foram submetidos à análise de variância simples e conjunta e as médias comparadas pelo teste de Scott-Knot. Os resultados permitiram afirmar que o comportamento diferenciado entre os genótipos de feijão-caupi quanto ao PCG independe das condições ambientais. A interação significativa de genótipo x ambiente para o PGS indica a possibilidade de seleção de materiais mais adaptados para diferentes ambientes de MS. As médias de PGS obtidas com os genótipos mais produtivos indicam a possibilidade de sucesso no cultivo comercial de feijão-caupi de porte semi-ereto em MS

A new view of electrochemistry at highly oriented pyrolytic graphite

Major new insights on electrochemical processes at graphite electrodes are reported, following extensive investigations of two of the most studied redox couples, Fe(CN)64–/3– and Ru(NH3)63+/2+. Experiments have been carried out on five different grades of highly oriented pyrolytic graphite (HOPG) that vary in step-edge height and surface coverage. Significantly, the same electrochemical characteristic is observed on all surfaces, independent of surface quality: initial cyclic voltammetry (CV) is close to reversible on freshly cleaved surfaces (>400 measurements for Fe(CN)64–/3– and >100 for Ru(NH3)63+/2+), in marked contrast to previous studies that have found very slow electron transfer (ET) kinetics, with an interpretation that ET only occurs at step edges. Significantly, high spatial resolution electrochemical imaging with scanning electrochemical cell microscopy, on the highest quality mechanically cleaved HOPG, demonstrates definitively that the pristine basal surface supports fast ET, and that ET is not confined to step edges. However, the history of the HOPG surface strongly influences the electrochemical behavior. Thus, Fe(CN)64–/3– shows markedly diminished ET kinetics with either extended exposure of the HOPG surface to the ambient environment or repeated CV measurements. In situ atomic force microscopy (AFM) reveals that the deterioration in apparent ET kinetics is coupled with the deposition of material on the HOPG electrode, while conducting-AFM highlights that, after cleaving, the local surface conductivity of HOPG deteriorates significantly with time. These observations and new insights are not only important for graphite, but have significant implications for electrochemistry at related carbon materials such as graphene and carbon nanotubes