Foam Glass Crystalline Granular Material from a Polymineral Raw Mix

The article is devoted to the development of resource-saving technology of porous granular materials for energy-efficient construction. The relevance of the work for international research is to emphasize expanding the raw material base of porous lightweight concrete aggregates at the expense of technogenic and substandard materials. The work aims to study the processes of porization of glass crystalline granules from polymineral raw materials mixtures. The novelty of the work lies in the establishment of regularities of thermal foaming of glass crystalline granules when using waste of magnetic separation of skarn-magnetite (WMS) ores and lignite clay. Studies of liquid glass mixtures with various mineral fillers revealed the possibility of the formation of a porous structure with the participation of opoka, WMS and lignite clay. This is due to the presence in the materials of substances that exhibit thermal activity with the release of a gas phase. The foaming efficiency of the investigated materials increases when combined with glass breakage. The addition of WMS and lignite clay to the glass mixture increases the pore size in comparison with foam glass. The influence of the composition of raw mixtures on the molding and stability of granules is determined. The addition of sodium carbonate helps to strengthen the raw granules and reduce the softening temperature of the mass. The composition of the molding mixture of glass breakage, liquid glass and a multicomponent additive is developed, which provides an improvement in the molding properties of the glass mass, foaming of granules at a temperature of 750 °C. Foam glass crystalline granules have polymodal porosity, characterized by a density of 330–350 kg/m3, a compressive strength of 3.2–3.7 MPa, and a thermal conductivity of 0.057–0.061 W/(m·°C). Accordingly, the developed granules have a high potential use in structural and heat-insulating concretes.

Thermal plasticity in behavioural traits mediates mating and reproductive dynamics in an ectotherm

Global changes in temperature potentially influence sexual selection by restricting opportunities for activity. However, explicit tests of the behavioural mechanisms linking thermal variation to mating and reproductive performance are rare. We address this gap in a temperate lizard by combining social network analysis with molecular pedigree reconstruction in a large-scale thermal manipulation experiment. Populations exposed to a more restrictive (cooler) thermal regime presented fewer high activity days compared to populations exposed to a warmer regime. While plasticity in thermal activity responses masked overall differences in activity levels, prolonged restriction nevertheless affected the timing and consistency of male-female interactions. Less active females in the cool thermal regime were significantly less likely to reproduce, which subsequently limited male mating. Surprisingly, this did not correspond to a heightened intensity of sexual selection or shifts in the targets of sexual selection. Thus, populations facing thermal activity restriction may possess limited potential for evolutionary response.

The Evolution of Peteroa Volcano (Chile–Argentina) Crater Lakes Between 1984 and 2020 Based on Landsat and Planet Labs Imagery Analysis

One of the major challenges in the understanding of the crater lakes dynamics and their connection with magmatic/hydrothermal processes is the continuous tracking of the physical behavior of lakes, especially in cases of remote and poorly accessible volcanoes. Peteroa volcano (Chile–Argentina border) is part of the Planchón–Peteroa–Azufre Volcanic Complex, one of the three volcanoes in the Southern Volcanic Zone of the Andes with crater lakes. Peteroa volcano is formed by a ∼5 km diameter caldera-type crater, which hosts four crater lakes and several fumarolic fields. Peteroa volcano has a large history of eruptive activity including phreatic-and-phreatomagmatic explosions and several episodes of strong degassing from its crater lakes. Here, we used TIR and SWIR bands from Landsat TM, ETM+, and OLI images available from October 1984 to December 2020 to obtain thermal parameters such as thermal radiance, brightness temperature, and heat fluxes, and Planet Labs Inc. images (RapidEye and PlanetScope) available between May 2009 and December 2020 to obtain physical parameters such as area, color, and state (liquid or frozen) of the crater lakes. We reviewed the historical eruptive activity and compared it with thermal and physical data obtained from satellite images. We determined the occurrence of two eruptive/thermal cycles: 1) Cycle 1 includes the formation of a new fumarolic field and two active craters during a short eruptive period, which includes thermal activity in three of the four crater lakes, and a strong degassing process between October 1998 and February 2001, coincident with a peak of volcanic heat flux (Qvolc) in two craters. The cycle finished with an eruptive episode (September 2010–July 2011). 2) Cycle 2 is represented by the thermal reactivation of two crater lakes, formation and detection of thermal activity in a new nested crater, and occurrence of a new eruptive episode (October 2018–April 2019). We observed a migration of the thermal and eruptive activity between the crater lakes and the interconnection of the pathways that feed the lakes, in both cases, partially related to the presence of two deep magma bodies. The Qvolc in Peteroa volcano crater lakes is primarily controlled by volcanic activity, and seasonal effects affect it at short-term, whilst at long-term, seasonal effects do not show clear influences in the volcanic heat fluxes. The maximum Qvolc measured between all crater lakes during quiescent periods was 59 MW, whereas during unrest episodes Qvolc in single crater lakes varied from 7.1 to 38 MW, with Peteroa volcano being classified as a low volcanic heat flux system. The detection of new thermal activity and increase of Qvolc in Peteroa volcano previous to explosive unrest can be considered as a good example of how thermal information from satellite images can be used to detect possible precursors to eruptive activity in volcanoes which host crater lakes.

Innovative functional polymerization of pyrrole-N-propionic acid onto WS2 nanotubes using cerium-doped maghemite nanoparticles for photothermal therapy

Tungsten disulfide nanotubes (WS2-NTs) were found to be very active for photothermal therapy. However, their lack of stability in aqueous solutions inhibits their use in many applications, especially in biomedicine. Few attempts were made to chemically functionalize the surface of the NTs to improve their dispersability. Here, we present a new polymerization method using cerium-doped maghemite nanoparticles (CM-NPs) as magnetic nanosized linkers between the WS2-NT surface and pyrrole-N-propionic acid monomers, which allow in situ polymerization onto the composite surface. This unique composite is magnetic, and contains two active entities for photothermal therapy—WS2 and the polypyrrole. The photothermal activity of the composite was tested at a wavelength of 808 nm, and significant thermal activity was observed. Moreover, the polycarboxylated polymeric coating of the NTs enables effective linkage of additional molecules or drugs via covalent bonding. In addition, a new method was established for large-scale synthesis of CM-NPs and WS2-NT-CM composites.

Mt. Etna Paroxysms of February–April 2021 Monitored and Quantified through a Multi-Platform Satellite Observing System

On 16 February 2021, an eruptive paroxysm took place at Mt. Etna (Sicily, Italy), after continuous Strombolian activity recorded at summit craters, which intensified in December 2020. This was the first of 17 short, but violent, eruptive events occurring during February–April 2021, mostly at a time interval of about 2–3 days between each other. The paroxysms produced lava fountains (up to 1000 m high), huge tephra columns (up to 10–11 km above sea level), lava and pyroclastic flows, expanding 2–4 km towards East and South. The last event, which was characterised by about 3 days of almost continuous eruptive activity (30 March–1 April), generated the most lasting lava fountain (8–9 h). During some paroxysms, volcanic ash led to the temporary closure of the Vincenzo Bellini Catania International Airport. Heavy ash falls then affected the areas surrounding the volcano, in some cases reaching zones located hundreds of kilometres away from the eruptive vent. In this study, we investigate the Mt. Etna paroxysms mentioned above through a multi-platform satellite system. Results retrieved from Advanced Very High Resolution Radiometer (AVHRR), Moderate Resolution Imaging Spectroradiometer (MODIS), and Spinning Enhanced Visible and Infrared Imager (SEVIRI), starting from outputs of the Robust Satellite Techniques for Volcanoes (RSTVOLC), indicate that the 17th paroxysm (31 March–1 April) was the most powerful, with values of radiative power estimated around 14 GW. Moreover, by the analysis of SEVIRI data, we found that the 5th and 17th paroxysms were the most energetic. The Multispectral Instrument (MSI) and the Operational Land Imager (OLI), providing shortwave infrared (SWIR) data at 20/30 m spatial resolution, enabled an accurate localisation of active vents and the mapping of the areas inundated by lava flows. In addition, according to the Normalized Hotspot Indices (NHI) tool, the 1st and 3rd paroxysm (18 and 28 February) generated the largest thermal anomaly at Mt. Etna after June 2013, when Landsat-8 OLI data became available. Despite the impact of clouds/plumes, pixel saturation, and other factors (e.g., satellite viewing geometry) on thermal anomaly identification, the used multi-sensor approach allowed us to retrieve quantitative information about the 17 paroxysms occurring at Mt. Etna. This approach could support scientists in better interpreting changes in thermal activity, which could lead to future and more dangerous eruptions.

Theoretical dependence of the strength of a plasma coating taking into account the mutual thermal effect of the sprayed particles

Перспективным способом восстановления изношенных деталей является газоплазменное напыление, позволяющее получать заданные эксплуатационные свойства поверхности. В статье теоретически вычислена вероятность взаимодействия напыляемых частиц в период их тепловой активности, зависящая от единственного параметра равного произведению числа напыленных частиц и квадрата отношения радиуса диска частицы на подложке к радиусу пятна напыления. Получено аналитическое выражение прочности плазменного покрытия на отрыв от параметров процесса напыления с учетом взаимного теплового влияния напыляемых частиц от единственного безразмерного параметра. Безразмерный параметр равен отношению произведения времени термической активности частиц, массового расхода, коэффициента прилипания, квадрата радиуса диска частицы на подложке к произведению массы частицы и квадрата радиуса пятна напыления. Gas-plasma spraying is a promising method for the restoration of worn-out parts, which makes it possible to obtain the performance properties of the surface. In the article the probability of interaction of the sprayed particles during the period of their thermal activity is theoretically calculated, depending on a single parameter equal to the product of the number of sprayed particles and the square the ratio of the radius of the disk of the particle on the substrate to the radius of the deposition spot. An analytical expression is obtained for the separation strength of a plasma coating from the parameters of the spraying process, taking into account the mutual thermal effect of the sprayed particles from a single dimensionless parameter. The dimensionless parameter is equal to the ratio of the product of the time of thermal activity of particles, mass flow rate, adhesion coefficient, square of the radius of the disk of the particle on the substrate to the product of the mass of the particle and the square of the radius of the spray spot.

Gamma-Ray and Neutrino Signals from Accretion Disk Coronae of Active Galactic Nuclei

To explain the X-ray spectra of active galactic nuclei (AGN), non-thermal activity in AGN coronae such as pair cascade models has been extensively discussed in the past literature. Although X-ray and gamma-ray observations in the 1990s disfavored such pair cascade models, recent millimeter-wave observations of nearby Seyferts have established the existence of weak non-thermal coronal activity. In addition, the IceCube collaboration reported NGC 1068, a nearby Seyfert, as the hottest spot in their 10 yr survey. These pieces of evidence are enough to investigate the non-thermal perspective of AGN coronae in depth again. This article summarizes our current observational understanding of AGN coronae and describes how AGN coronae generate high-energy particles. We also provide ways to test the AGN corona model with radio, X-ray, MeV gamma ray, and high-energy neutrino observations.