Comment on “Investigation on Anomalous Thermal Quenching of Mn4+ Luminescence in A2XF6:Mn4+” [ECS J. Solid State Sci. Technol. 10 076007 (2021)]

Adachi (ECS J. Solid State Sci. Technol.,10, 076007(2021)) reported that an anomalous enhancement of integrated intensity of Mn4+ luminescence (IPL) in A2XF6:Mn4+ phosphors with increasing lattice temperature was an intrinsic property of the phosphors due to the increased phonon number that makes it possible to gain the parity and spin-forbidden 2Eg → 4A2g transitions.I argue in this comment that it seems still unconvincing to ascribe the anomalous increase of IPL with temperature as an intrinsic property of Mn4+-doped fluorides. Since theoretical derivations of the formulas expressing temperature dependence of the intensities were based on an unjustified assumption.

Enhanced anomalous magnetization in carbonyl iron by Ni+ ion beam irradiation

We investigate the magnetic properties in carbonyl iron (CI) particles before and after Ni$$^{+}$$ + and H$$^{+}$$ + ion beam irradiation. Upon increasing temperatures, the saturation magnetization ($$M_{\text {s}}$$ M s ) in hysteresis loops exhibits an anomalous increase at a high temperature for the unirradiated and the Ni$$^{+}$$ + -beam-irradiated samples, unlike in H$$^{+}$$ + -beam-irradiated sample. Moreover, the magnetization values at low and high temperatures are more intense after Ni$$^{+}$$ + beam irradiation, whereas after H$$^{+}$$ + beam irradiation those are remarkably suppressed. Hematite ($$\alpha $$ α -Fe$$_{2}$$ 2 O$$_{3}$$ 3 ) phase introduced on the surface of our CI particles undergoes the Morin transition that was observed in our magnetization-temperature curves. The Morin transition causing canted antiferromagnetism above the Morin temperature was found in the unirradiated and Ni$$^{+}$$ + -beam-irradiated samples, but not in H$$^{+}$$ + -beam-irradiated sample. It is thus revealed that the CI particles undergoing the Morin transition cause the anomalous increase in $$M_{\text {s}}$$ M s . We may suggest that Ni$$^{+}$$ + ion beam increases uncompensated surface spins on the CI particles resulting in a more steep Morin transition and the intensified $$M_{\text {s}}$$ M s . Ion-beam irradiation may thus be a good tool for controlling the magnetic properties of CI particles, tailoring our work for future applications.

Enhanced Magnetization in a Frustrated Spin System by Ni+ Ion Beam Irradiation

We investigate the magnetic properties in a frustrated spin system of carbonyl iron (CI) particles before and after Ni+ ion beam irradiation. Upon increasing temperatures, the saturation magnetization exhibits an anomalous increase, which is more intense after the beam irradiation. The zero-field cooled (ZFC) magnetization data show an anomalous increase up to 300 K, regardless of the beam irradiation. After the irradiation, unlike in the unirradiated CI particles, the ZFC curve shows separated regimes, reflecting two distributions of the blocking temperature, which may be related to the particle distribution summed with two distribution functions. After the irradiation, strong interparticle interaction may be present due to the effect of dipolar interaction among CI particles doped Ni ions, leading to the enhanced magnetization. We may suggest that the anomalous magnetization behavior can be ascribed to frustration in the internal magnetic order for the unirradiated CI particles, and further interparticle interaction for the irradiated CI particles.

Focal superior quadrant haemorrhages in post COVID-19 patient: A target for personalized medicine

Purpose: To report a case of multiple superior quadrant intraretinal haemorrhages in post-COVID-19 patient. Case description: A 58-year-old male with a history of coronary artery disease and hypertension, presented with multiple superior quadrant intraretinal haemorrhages in the superonasal quadrant of the left eye 1 month after hospitalization for COVID-19. The right eye was normal. During his 10-day stay, he was treated with hydroxychloroquine, lopinavir + ritonavir, ceftriaxone, and his pre-existing antiplatelet therapy. During hospitalization, a complete medical work up showed an anomalous increase in D-dimer. He did not require intensive care support. Conclusions: In this report, we focused on the origin of retinal bleeding in a post COVID-19 patient, likely due to a focal occlusion of a vessel. Considering the nature of SARS-CoV-2 infection, we hypothesize that retinal haemorrhages were caused by a combination of factors including the patient’s antiplatelet therapy and the thrombotic microvascular injury caused by the virus.

The effect of titanium-carbon mixture mechanical activation on SHS pressing parameters and consolidated titanium carbide microstructure

The paper studies the effect of mechanical activation (MA) modes when stirring a stoichiometric mixture of titanium and soot powders in a ball mill on the properties of mixtures, combustion parameters, relative density, and the microstructure of consolidated titanium carbide samples obtained by SHS. MA conditions for Ti + C reaction mixtures in a ball mill were determined. An increase in the mass of grinding bodies activates the MA mechanism. It was shown that the greatest effect from MA was obtained with a two-stage preparation of mixtures: firstly, the titanium powder was activated separately, then the components were mixed together, and this process included not only their mixing, but also soot powder activation. It was found that combustion behavior is affected by the activation of not only titanium, but also soot. After MA of both components, an anomalous increase in the burning rate (more than 100 cm/s) was found on pressed samples. At the bulk density, there was no effect of MA on the mixture combustion process, since in this case the burning rate of all mixtures was in the range of 1.5–2.5 cm/s. It was revealed that MA of reagents for pressed samples leads to an increase in the combustion temperature, an increase in the relative density of the consolidated refractory product to 93–95 %, and a decrease in the average size of TiC grains. A decrease in the residual porosity of consolidated TiC is due to an increase in the hot pressing temperature and plasticity of the product synthesized during the reaction mixture combustion after MA. The main reason is an increase in the exothermic interaction rate. It was shown that MA when mixing reagents makes it possible to control combustion parameters, the microstructure of consolidated products and opens up new opportunities for obtaining refractory materials featuring a unique structure and properties by SHS pressing.

El Niño as a predictor of round sardinella distribution along the northwest African coast

<p>The El Niño Southern Oscillation (ENSO) produces global marine environment conditions that can cause changes in abundance and distribution of distant fish populations worldwide. Understanding mechanisms acting locally on fish population dynamics is crucial to develop forecast skill useful for fisheries management. The present work addresses the role played by ENSO on the round sardinella population biomass and distribution in the central-southern portion of the Canary Current Upwelling System (CCUS). A combined physical-biogeochemical framework is used to understand the climate influence on the hydrodynamical conditions in the study area. Then, an evolutionary individual-based model is used to simulate the round sardinella spatio-temporal biomass variability. According to model experiments, anomalous oceanographic conditions forced by El Niño along the African coast cause anomalies in the latitudinal migration pattern of the species. A robust anomalous increase and decrease of the simulated round sardinella biomass is identified in winter off the Cape Blanc and the Saharan coast region, respectively, in response to El Niño variations. The resultant anomalous pattern is an alteration of the normal migration between the Saharan and the Mauritanian waters. It is primarily explained by the mod- ulating role that El Niño exerts on the currents off Cape Blanc, modifying therefore the normal migration of round sardinella in the search of acceptable temperature conditions. This climate signature can be potentially predicted up to six months in advance based on El Niño conditions in the Pacific.</p>

Space Study of a Red Tide-Related Environmental Disaster near Kamchatka Peninsula in September–October 2020

The results of space monitoring of an extreme ecological situation near Kamchatka Peninsula, which was responsible for a mass death of hydrobionts in autumn 2020, are presented. The analysis of long-term series of satellite data (>15 000 scenes) on sea surface temperature (from 1981 to 2020) and concentration of chlorophyll a (from 2000 to 2020) showed strong positive temperature anomalies (deviations from a climate norm 3–6°C) in the studied region in July–September 2020, which resulted in anomalous increase in the concentration of chlorophyll a (5–8 times higher than the background values) in the end of September–the beginning of October 2020. As a result, a significantly changed biogenic regime led to harmful bloom of algae (red tide), which caused death of hydrobionts both in Avacha Bay and coastal regions of the entire Kamchatka Peninsula.

Влияние тока, ограниченного объемным зарядом, на диэлектрические свойства поликристаллических пленок фуллерита С-=SUB=-60-=/SUB=-

In the frequency range from 30 Hz to 1 MHz, the dielectric properties of polycrystalline fullerite films with a thickness of about 300 nm, which are part of p-type Si / C60 / InGa structures, were studied under the influence of constant electric fields with a strength of up to 33 MV / m. It was found that at negative polarity of the InGa electrode, when the injection of electrons from the metal into the fullerite is facilitated, at frequencies less than 1000 Hz, an anomalous increase in the electrical capacity of the sample is observed, while the capacitance at a low frequency exceeds the capacitance at a high frequency by more than 1000 times. An explanation for this effect is proposed.

Unravelling the Nature of a Toluene-Fumaronitrile Complex

The undertaken research allows to explain and characterize the occurrence and anomalous increase of an additional absorption band observed in the spectrum of fumaronitrile dissolved in toluene. The formation of...