RESUMO
Lab-on-a-Chip (LoC) devices are described as versatile, fast, accurate, and low-cost platforms for the handling, detection, characterization, and analysis of a wide range of suspended particles in water-based environments. However, for gas-based applications, particularly in atmospheric aerosols science, LoC platforms are rarely developed. This review summarizes emerging LoC devices for the classification, measurement, and identification of airborne particles, especially those known as Particulate Matter (PM), which are linked to increased morbidity and mortality levels from cardiovascular and respiratory diseases. For these devices, their operating principles and performance parameters are introduced and compared while highlighting their advantages and disadvantages. Discussing the current applications will allow us to identify challenges and determine future directions for developing more robust LoC devices to monitor and analyze airborne PM.
Assuntos
Dispositivos Lab-On-A-Chip , Material Particulado , Monitoramento Ambiental , Tamanho da Partícula , Material Particulado/análiseRESUMO
This scoping study presents an investigation of the total and bioaccessible mercury concentrations in road dust (RD) from three international urban sites, where a one-off sampling campaign was conducted at each. This was done to address the hypothesis that the matrix in which mercury is found influences its ability to become accessible to the body once inhaled. For that purpose, the samples were analysed for total and pulmonary bioaccessible mercury and the data compared to the chemical structure of individual particles by SEM. The results obtained from this study suggest that a high mercury content does not necessarily equate to high bioaccessibility, a phenomenon which could be ascribed to the chemical character of the individual particles. It was found that the Manchester samples contained more pulmonary soluble mercury species (as determined by elemental associations of Hg and Cl) in comparison to the other two samples, Curitiba, Brazil, and Johannesburg, South Africa. This finding ultimately underlines the necessity to conduct a site-specific in-depth analysis of RD, to determine the concentration, chemical structure and molecular speciation of the materials within the complex matrix of RD. Therefore, rather than simply assuming that higher bulk concentrations equate to more significant potential human health concerns, the leaching potential of the metal/element in its specific form (for example as a mineral) should be ascertained. The importance of individual particle behaviour in the determination of human health risk is therefore highlighted.
Assuntos
Poluentes Atmosféricos/toxicidade , Poeira/análise , Mercúrio/análise , Mercúrio/toxicidade , Poluentes Atmosféricos/análise , Poluentes Atmosféricos/farmacocinética , Disponibilidade Biológica , Brasil , Microanálise por Sonda Eletrônica/métodos , Monitoramento Ambiental , Humanos , Mercúrio/farmacocinética , Microscopia Eletrônica de Varredura , África do Sul , Análise Espectral Raman , Reino UnidoRESUMO
Survival and life quality of breast cancer patients could be improved by more aggressive chemotherapy for those at high metastasis risk and less intense treatments for low-risk patients. Such personalized treatment cannot be currently achieved due to the insufficient reliability of metastasis risk prognosis. The purpose of this study was therefore, to identify novel histopathological prognostic markers of metastasis risk through exhaustive computational image analysis of 80 size and shape subsets of epithelial clusters in breast tumors. The group of 102 patients had a follow-up median of 12.3 years, without lymph node spread and systemic treatments. Epithelial cells were stained by the AE1/AE3 pan-cytokeratin antibody cocktail. The size and shape subsets of the stained epithelial cell clusters were defined in each image by use of the circularity and size filters and analyzed for prognostic performance. Epithelial areas with the optimal prognostic performance were uniformly small and round and could be recognized as individual epithelial cells scattered in tumor stroma. Their count achieved an area under the receiver operating characteristic curve (AUC) of 0.82, total area (AUC = 0.77), average size (AUC = 0.63), and circularity (AUC = 0.62). In conclusion, by use of computational image analysis as a hypothesis-free discovery tool, this study reveals the histomorphological marker with a high prognostic value that is simple and therefore easy to quantify by visual microscopy.
RESUMO
Recent advances in cryo-electron microscopy (cryo-EM) have made it possible to solve structures of biological macromolecules at near atomic resolution. Development of more stable microscopes, improved direct electron detectors and faster software for image processing has enabled structural solution of not only large macromolecular (megadalton range) complexes but also small (~60 kDa) proteins. As a result of the widespread use of the technique, we have also witnessed new developments of techniques for cryo-EM grid preparation of membrane protein samples. This includes new types of solubilization strategies that better stabilize these protein complexes and the development of new grid supports with proven efficacy in reducing the motion of the molecules during electron beam exposure. Here, we discuss the practicalities and recent challenges of membrane protein sample preparation and vitrification, as well as grid support and foil treatment in the context of the structure determination of protein complexes by single particle cryo-EM.
RESUMO
ABSTRACT The objective of this work was to characterize the aspects related to the diameter of household aerosol droplets. The droplet spectra was determined in a particle size analyzer (Mastersizer S®, version 2.19). The experiment was carried out in a completely randomized design, arranged on a 6 x 2 factorial scheme, with six replications. Two samples were evaluated, of 6 different aerosols available on the market and codified as: BAT, REB, RCJ, RAT, SMI and M. The following parameters were analyzed: 1) the percentage of the sprayed volume containing drops with diameter equal to 15 µm or less; 2) the relative amplitude of the diameter of the droplets in the applied spurt; and the 3) the diameter of droplets for which 10% (Dv0.1), 50% (Dv0.5) and 90% (Dv0.9) of the sprayed volumes presented droplets with lesser diameters. The aerosols evaluated presented characteristics of droplets within the limits of effective tolerance according to the official resolution of the national regulating agency.
RESUMO O objetivo deste trabalho foi caracterizar os aspectos relacionados ao diâmetro de gotas de aerossóis domissanitários. O espectro de gotas foi determinado num analisador de partículas (Mastersizer S®, versão 2.19), utilizando o delineamento inteiramente casualizado em arranjo fatorial 6 x 2, com seis repetições. Avaliaram-se duas amostras, de seis diferentes marcas de aerossóis disponíveis no mercado e codificados como: BAT, REB, RCJ, RAT, SMI e M. Os seguintes parâmetros foram analisados: 1) a porcentagem do volume pulverizado contendo gotas com diâmetro igual ou inferior a 15 µm; 2) a amplitude relativa ao diâmetro de gotas do jato aplicado; e 3) os diâmetros de gotas para os quais 10% (Dv0,1), 50% (Dv0,5) e 90% (Dv0,9) dos volumes pulverizados apresentaram gotas de diâmetro inferiores. Os aerossóis avaliados apresentaram características de gotas que atenderam aos limites de tolerância vigente em resolução oficial da agência reguladora nacional.
RESUMO
The use of a new soil particle size distribution analysis methodology is presented in connection with the study of particle size distribution in soils covered by natural forest and sugar cane crop cultivated during 16, 30 and 50 years, continuously. The technique is based on the attenuation of a gamma-ray beam by a conventional soil/water suspension under sedimentation. Results show a significant difference in clay content for the upper soil layer as a function of sugar cane cultivation.
É apresentado o uso de uma nova metodologia de análise da distribuição de tamanho de partículas de solo, em amostras de terra sob floresta nativa e submetido ao cultivo de cana-de-açúcar por 16, 30 e 50 anos consecutivos. A técnica para análise granulométrica do solo baseia-se na atenuação de um feixe de radiação gama, por uma suspensão convencional terra/água em sedimentação. Os resultados indicam uma diferença significativa dos teores de argila nas camadas superficiais do solo em função do cultivo com cana-de-açúcar.
RESUMO
The use of a new soil particle size distribution analysis methodology is presented in connection with the study of particle size distribution in soils covered by natural forest and sugar cane crop cultivated during 16, 30 and 50 years, continuously. The technique is based on the attenuation of a gamma-ray beam by a conventional soil/water suspension under sedimentation. Results show a significant difference in clay content for the upper soil layer as a function of sugar cane cultivation.
É apresentado o uso de uma nova metodologia de análise da distribuição de tamanho de partículas de solo, em amostras de terra sob floresta nativa e submetido ao cultivo de cana-de-açúcar por 16, 30 e 50 anos consecutivos. A técnica para análise granulométrica do solo baseia-se na atenuação de um feixe de radiação gama, por uma suspensão convencional terra/água em sedimentação. Os resultados indicam uma diferença significativa dos teores de argila nas camadas superficiais do solo em função do cultivo com cana-de-açúcar.