Scalar radiation from a radially infalling source into a Schwarzschild black hole in the framework of quantum field theory

We investigate the radiation to infinity of massless scalar field from a source falling radially towards a Schwarzschild black hole using the framework of quantum field theory at tree level. In the case where the source falls from infinity, the monopole radiation is dominant for low initial velocities but higher multipoles become dominant at high initial velocities. It is found that, as in the electromagnetic and gravitational cases, at high initial velocities the energy spectrum for each multipole with $l \geq 1$ is approximately constant up to the fundamental quasinormal frequency and then drops to zero. We also investigate the case where the source falls from rest at a finite distance from the black hole. We find that the monopole and dipole contributions are dominant in this case. We point out that this case needs to be distinguished carefully from the unphysical process where the source abruptly appears at rest and starts falling, which would result in radiation of an infinite amount of energy. We also investigate the radiation of massless scalar field to the horizon of the black hole, finding some features similar to the gravitational case

Glazing-related problems due to high temperatures in double skin façades

The thermal behaviour of a double skin façade building is modelled using the DOE-2 building energy simulation program. Maximum temperatures of glazed components of the double skin façade are determined to assess the occurrence of glazing-related problems, such as reduced thermal and aesthetic performance, increased maintenance costs and even injury hazards. The importance of detailed thermal modelling of double skin façades and of its glazed componentes is concluded

Titanium nanoparticles in sedimented dust aggregates from urban children’s parks around coal ashes wastes

Recently, an increased interest in nanoscience applications can be observed in various fields. Soils around coal power plants may contain potentially hazardous elements (PHEs) and nanoparticles (NPs), which can be neo-produced pollutants or can be a product of industrial coal utilization. While titanium (Ti)-NPs contact is a worldwide concern, transference of Ti-NPs to infants as well as their human health impact is still imprecise. In general, the toxicity and the human health risk assessment associated with the presence of some Ti-NPs, needs to be determined with a robust and fast analytical methodology. The mode of occurrences of Ti-NPs in children’s playgrounds were evaluated by advanced electron microscopy techniques (field emission scanning electron microscope-FE-SEM and high resolution transmission electron microscope-HR-TEM) coupled with an energy dispersive X-ray microanalysis system (EDS); Raman Spectroscopy (RS); and X-Ray Diffractions (XRD). The reported data showed that when the size of the NPs reduced, the ability of sedimented dust aggregates to transport PHEs increased. Carbonaceous matter and amorphous silica were the main factors that influenced the distribution of PHEs among the studied Ti-NPs aggregates. Together, the data indicate that the proportions of PHEs in sedimented urban dust in the urban area around coal power plants are mainly due to emissions related to vehicle traffic and the coal industry, representing immediate environmental risks and long-term health risks. Therefore, actions are required to monitor and mitigate the impact of Ti-NPs aggregates in the urban area and nearby ecosystems. Such pollutants are necessary to be observed as children represent a susceptible cluster likened to adults. The currently estimated risk can be influenced by factors such as absorption, form of Ti-NPs, particle fraction, particle size, and physico-geochemical properties in relation to toxicity, among others. Analysis of actual particle concentrations in human organs, as well as organ concentrations and effects in liver and the reproductive system after chronic exposure to well-characterized Ti-NPs in animals are recommended to refine this assessment

Nanoparticles as vectors of other contaminants in estuarine suspended sediments: Natural and real conditions

Studding the behaviour and danger of nanoparticles (NPs, minerals and amorphous phases) in the estuarine ecosystem is presently incomplete by the lack of measureable description of NPs in the ecological conditions, such as suspended-sediments (SS). In the last years, several works have revealed the toxic consequences of ultra-fine and nanoparticulate compounds on diverse systems, raising apprehensions over the nanocontaminants behaviour and destiny in the numerous ecological partitions. The general objective of the manuscript is to explain the geochemical conditions of the LES (Laguna estuarine system, southern Brazil) suspended sediments covering an area around the main South American coal plant, enhancing the creation of future public policies for environmental recovery projects. Subsequently the discharge of nanoparticles and toxic element (TE) in the ecosystem, NPs react with several constituents of the nature and suffers active alteration progressions. Contamination coming from engineering actions, wastewater, are something identifiable, however when these contaminations are accompanied by other contamination sources (e.g. mining and farming) the work gets defaulted. By combining material about the concentration of TE contaminants and NPs occurrences, this work offers novel visions into contaminant contact and the possible effects of such exposure on estuarine systems in Brazil. The results presented here will be useful for different areas of estuaries around the world

Nanoparticles from evaporite materials in Colombian coal mine drainages

Ultrathin and nanometric materials (minerals and amorphous phases) are detected in transitory deposits of potential hazardous elements (PHEs), especially in acidic coal mine drainages. The main goal of this work was to evaluate the occurrence of PHEs in nanoparticles (NPs) in evaporative structures in coal mining areas with high concentrations of PHEs. The precipitates were sampled in several coal mining areas in Colombia, with the purpose of evaluating the geochemical and environmental structures. In the present work, to better diagnose areas affected by coal mining, an innovative analytical procedure is proposed to define the association between PHEs in mine drainage sediments. The procedure includes the analytical study with X-Ray Diffraction (XRD) and advanced electron microscopy, before and after a series of sequential extractions to separate amorphous, magnetic, and crystalline compounds. Of the three main types of precipitates identified, the yellowish precipitates had the highest amounts of PHEs while the white precipitates had only small amounts of PHEs and the greenish precipitates contained TiO2 nanoparticles. The results from this study will be usable for more than fifty countries that have coal mine drainages