Characteristics of fine and ultrafine aerosols in the London underground

\ua9 2022 The Authors. Underground railway systems are recognised spaces of increased personal pollution exposure. We studied the number-size distribution and physico-chemical characteristics of ultrafine (PM0.1), fine (PM0.1–2.5) and coarse (PM2.5–10) particles collected on a London underground platform. Particle number concentrations gradually increased throughout the day, with a maximum concentration between 18:00 h and 21:00 h (local time). There was a maximum decrease in mass for the PM2.5, PM2.5–10 and black carbon of 3.9, 4.5 and ~ 21-times, respectively, between operable (OpHrs) and non-operable (N-OpHrs) hours. Average PM10 (52 μg m−3) and PM2.5 (34 μg m−3) concentrations over the full data showed levels above the World Health Organization Air Quality Guidelines. Respiratory deposition doses of particle number and mass concentrations were calculated and found to be two- and four-times higher during OpHrs compared with N-OpHrs, reflecting events such as train arrival/departure during OpHrs. Organic compounds were composed of aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) which are known to be harmful to health. Specific ratios of PAHs were identified for underground transport that may reflect an interaction between PAHs and fine particles. Scanning transmission electron microscopy (STEM) chemical maps of fine and ultrafine fractions show they are composed of Fe and O in the form of magnetite and nanosized mixtures of metals including Cr, Al, Ni and Mn. These findings, and the low air change rate (0.17 to 0.46 h−1), highlight the need to improve the ventilation conditions

Microclima e índices de conforto térmico em sistemas de integração lavoura-pecuária-floresta no município de Campo Grande, Mato Grosso do Sul.

O objetivo deste trabalho foi avaliar índices de conforto térmico em sistemas de integração lavoura-pecuária-floresta, com eucalipto em arranjos de 14x2m (ILPF-1) e de 22x2m (ILPF-2) e árvores nativas dispersas com 5 árvores/ha-1 (ILPF-3), no Município de Campo Grande, Mato Grosso do Sul. O experimento foi conduzido na Embrapa Gado de Corte, em Campo Grande, MS, de julho a setembro de 2013. As avaliações foram realizadas mensalmente, em quatro dias consecutivos, em três horários (09h00, 12h00 e 15h00; GMT -04h00). Foram determinadas a temperatura do ar (°C), temperatura de globo negro (°C), temperatura de bulbo úmido (°C), umidade relativa do ar (%) e velocidade do vento (m s-1). Foram calculados o Índice de Temperatura e Umidade (ITU), Índice de Temperatura de Globo e Umidade (ITGU) e a Carga Térmica de Radiação (CTR). Em todos os sistemas, os maiores valores dos índices foram observados a pleno sol, às 12h00, resultando em ITU de 81 e ITGU de 88. À sombra, houve maior conforto térmico (ITU = 78 e ITGU = 79), e redução da Carga Térmica de Radiação de até 224,4 W.m-2. Conclui--se, assim, que a presença de árvores altera positivamente o ambiente e as mesmas são fundamentais para a melhoria do conforto térmico de animais criados em pastagens de regiões com clima quente.bitstream/item/158137/1/Microclima-e-indices-de-conforto.pd

High-resolution MCP-TimePix3 imaging/timing detector for antimatter physics

We present a hybrid imaging/timing detector for force sensitive inertial measurements designed for measurements on positronium, the metastable bound state of an electron and a positron, but also suitable for applications involving other low intensity, low energy beams of neutral (antimatter)-atoms, such as antihydrogen. The performance of the prototype detector was evaluated with a tunable low energy positron beam, resulting in a spatial resolution of approximate t