The size and velocity distribution of cosmic dust particles entering the Earth's atmosphere is uncertain. Here we show that the relative concentrations of metal atoms in the upper mesosphere, and the surface accretion rate of cosmic spherules, provide sensitive probes of this distribution. Three cosmic dust models are selected as case studies: two are astronomical models, the first constrained ...

• Chipping, sledging and hammering on metal, stone or concrete • Use of manual, pneumatic and power impact tools • Caulking, brushing and grinding • Drilling, scaling and scraping soldering and casting hot metals • Handling acids, caustics and creosoted materials • Gas welding, cutting and brazing • Drilling overhead • In environments of excessive dust • Electric arc welding and cutting, and ot...

Exposure to cobalt in the hard metal industry entails severe adverse health effects, including lung cancer and hard metal fibrosis. The main aim of this study was to determine exposure air concentration levels of cobalt and tungsten for risk assessment and dose-response analysis in our medical investigations in a Swedish hard metal plant. We also present mass-based, particle surface area, and p...

in this study, the removal of cd(ii) from aqueous solutions have been carried out using populusnigra saw dust as low-cost, readily available biosorbent. various physico-chemical parameters such as ph, initial metal ion concentration, and adsorbent dosage level and contact time were studied at room temperature to optimize the conditions for maximum adsorption. the central composite design was ca...

Iron oxide occurs as a dust in many industries apart from iron-ore mining. It is found in silver polishing, electric welding, and boiler scaling, as well as in the more obvious metal grinding, fettling, and blast furnace working where it may be mixed with varying amounts of silica. Some still consider iron oxide a harmless dust (Baldi, 1952) while others think that, like coal, it can produce ch...

The aim of this study is to analysis the performance of Robinia pseudoascacia (black locust tree) to accumulation some of heavy metals and compared with the concentration of these metals in falling dust Yazd highway green belt. In order to an experiment was conducted as factorial based on completely randomized design with four replications.The results showed that the concentration of, ...

Aims. Substellar objects have extremely long life-spans. The cosmological consequence for older objects are low abundances of heavy elements, which results in a wide distribution of objects over metallicity, hence over age. Within their cool atmosphere, dust clouds become a dominant feature, affecting the opacity and the remaining gas phase abundance of heavy elements. We investigate the influe...

Understanding variations of heavy metals in atmospheric particles between different functional areas is significant for pollution control and urban planning in cities. To reveal pollution and spatial distribution of heavy metals in atmospheric particles from different urban functional areas in Shijiazhuang in North China, 43 settled dust samples were collected over the main urban area and heavy...

It has long been known that ventilation is a costeffective method to lower respirable dust concentrations in all types of mining applications. The National Institute for Occupational Safety and Health has been working on a number of different research techniques that use ventilation as a critical component to lower respirable dust levels at surface and metal/nonmetal operations in the United St...