The application of spherical aberration correction and focal series restoration to high-resolution images of platinum nanocatalyst particles

A JEOL 2200FS transmission electron microscope equipped with a field emission gun, an objective lens spherical aberration corrector and an in-column energy filter has been used to acquire through focal series of high-resolution images of platinum nanocatalyst particles using a small value of the spherical aberration coefficient. The degree to which spherical aberration correction provides an improvement to image quality and interpretability for such particles is discussed, both with and without the use of through-focal series restoration. © 2006 IOP Publishing Ltd

Transmission electron microscopy of unstained hybrid Au nanoparticles capped with PPAA (plasma-poly-allylamine): Structure and electron irradiation effects

Hybrid (organic shell-inorganic core) nanoparticles have important applications in nanomedicine. Although the inorganic components of hybrid nanoparticles can be characterized readily using conventional transmission electron microscopy (TEM) techniques, the structural and chemical arrangement of the organic molecular components remains largely unknown. Here, we apply TEM to the physico-chemical characterization of Au nanoparticles that are coated with plasma-polymerized-allylamine, an organic compound with the formula C3H5NH2. We discuss the use of energy-filtered TEM in the low-energy-loss range as a contrast enhancement mechanism for imaging the organic shells of such particles. We also study electron-beam-induced crystallization and amorphization of the shells and the formation of graphitic-like layers that contain both C and N. The resistance of the samples to irradiation by high-energy electrons, which is relevant for optical tuning and for understanding the degree to which such hybrid nanostructures are stable in the presence of biomedical radiation, is also discussed. © 2014 Elsevier Ltd

Qualidade pós-colheita de tomates 'Débora' com utilização de diferentes coberturas comestíveis e temperaturas de armazenamento Quality of 'Debora' tomato using different edible coatings and storage temperatures

Este estudo visou avaliar o efeito de diferentes coberturas comestíveis sobre a qualidade pós-colheita do tomate de mesa cv. Débora. Foram utilizadas as seguintes coberturas: cera de carnaúba Fruit Wax H2 (18%), emulsão de resinas Fruit Wax M-AC (18%) e cera de carnaúba Megh Wax ECF-124 (18%); tomates sem cera serviram de controle. Foram utilizados 40 frutos por tratamento em delineamento inteiramente casualizado. Após a limpeza e aplicação das ceras, os frutos foram armazenados a 12,5&deg;C e 25&deg;C e 90% de umidade relativa. Análises para perda de massa fresca (%), coloração e qualidade foram realizadas durante quinze dias. No final do período de armazenagem, os frutos foram avaliados quanto à firmeza, pH, concentração de sólidos solúveis, vitamina C e acidez. Foi realizada também análise sensorial para frutos armazenados nas duas diferentes temperaturas. O tratamento com Megh Wax ECF-124 proporcionou menor perda de massa e frutos mais firmes em ambas as temperaturas. Tomates tratados com Fruit Wax M-AC e Megh Wax ECF-124 apresentaram maior porcentagem de frutos apropriados ao consumo. Não houve diferença significativa entre os tratamentos quanto à coloração e análises químicas, exceto para os frutos cobertos com Fruit Wax M-AC, que apresentaram menor teor de vitamina C em ambas as temperaturas e maior pH a 25&deg;C. As ceras Fruit Wax M-AC e Megh Wax ECF-124 não interferiram no sabor e no odor dos frutos. A aplicação de cera contribui para uma diminuição na perda de massa e decréscimo no número de frutos descartados devido a danos físicos e podridões, sendo que Megh Wax ECF-124 é mais eficiente na manutenção da qualidade de tomates de mesa.<br>This study aimed at evaluating the effect of edible coatings on tomato cv. Debora post-harvest quality. The following waxing emulsions were used: wax of carnauba Fruit Wax H2 (18%), emulsion of resins Fruit Wax M-AC (18%) and wax of carnauba Megh Wax ECF-124 (18%); tomatoes without wax were used as reference. A totally randomized experiment was installed using 40 fruits for each treatment. After cleaning and application of the waxes, the fruits were stored at 12,5&deg;C and 25&deg;C and 90% RH. Analyses for weight loss (%), color and quality were carried out during fifteen days. After storage, fruits were evaluated for firmness, pH, soluble concentration of solids, vitamin C, total acidity and a sensorial analysis. Tomatoes treated with Megh Wax ECF-124 presented minor weight losses and firmer fruits in both temperatures. Fruits treated with Fruit Wax M-AC and Megh Wax ECF-124 showed the highest percentage of fruits edible for consumption. There was no significant difference between treatments for color and chemical analyses, except for fruits covered with Fruit Wax M-AC, that showed low level of vitamin C on both temperatures and higher pH level at 25&deg;C. Fruit Wax M-AC and Megh Wax ECF-124 did not affect flavor and odor on fruits. Wax application contributed to reduce weight loss and the number of fruits discarted due to physical damage and diseases. Megh Wax ECF-124 was the most efficient wax for keeping fruit quality