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For the first time, the temperature evolution of the absorption spectra of Alq3 thin film, prepared by the method of vacuum thermal evaporation, was investigated in the range of 16–320 K. The optical energy gaps were obtained from direct allowed transitions at this temperature range by means of Tauc plots. [ABSTRACT FROM AUTHOR]

Halide perovskites recently emerged as promising materials for the detection of ionising radiation. Single crystals of halide perovskites exhibit very fast and bright scintillation when cooled and may outperform the best modern scintillators at temperatures below 100 K. In this work we report on low-temperature scintillation properties of CsPbCl3 single crystals, grown using the Bridgeman method. The temperature dependences of the luminescence and decay kinetics were studied using X-ray excitation. At low temperatures, the crystal exhibits an intense narrow-band emission at about 420 nm with very fast decay kinetics. This emission, of which a characteristic feature is the strong thermal quenching, is attributed to the radiative decays of bound and trapped excitons. The fast, middle, and slow decay time constants obtained from a fit of a sum of exponential functions to the decay curve at 10 K are 0.1, 1 and 11 ns, respectively. The scintillation light yield of CsPbCl3 at 7 K measured at excitation with α-particles from an 241Am source is estimated to be 140 ± 15% of a reference LYSO-Ce crystal and 19000 ± 2000 ph per MeV under 14 keV X-ray excitation at 10 K. It is concluded that owing to a reduced amplitude of the slow decay component, CsPbCl3 exhibits an ultra-fast scintillation response that is superior to that of other halide perovskites. The combination of sub-nanosecond response time and the encouraging light yield has the potential of establishing this material as first choice for scintillation applications that rely on prompt detector response at cryogenic temperatures. [ABSTRACT FROM AUTHOR]

We have obtained X-ray emission spectra of Ga and Ge in Ca3Ga2Ge4O14, X-ray emission OKα-spectra in Ca3Ga2Ge4O14, Ca3Ga2Ge4O14 + Ce3%, and Ca3Ga2Ge4O14 + Eu4% and Xray photoelectron spectra in Ca3Ga2Ge4O14 . Our X-ray spectral studies of the Ca3Ga2Ge4O14 gallogermanate have shown that the top of the valence band near the Fermi level is formed mainly by p states of gallium and germanium as well as p states of oxygen, whose intensity is sufficiently low. The middle of the valence band is formed by gallium 3d states with oxygen 2s states lying below them. These states are hybridized with 4p states of gallium and germanium because of which there are Kβ′′-satellites in the Kβ2-subbands of gallium and germanium. The bottom of the valence band is formed by 3d states of germanium, whose contribution to chemical bonding is insignificant. The X-ray emission bands of Ga and Ge in Ca3Ga2Ge4O14 and the photoelectron spectrum of the valence electrons of Ca3Ga2Ge4O14 are in good agreement. The OKα-band changes its fine structure only slightly upon doping Ca3Ga2Ge4O14 with Ce or Eu. The investigations of intrinsic luminescence under X-rays excitation of Ca3Ga2Ge4O14 gallogermanate are presented. [ABSTRACT FROM AUTHOR]

This work investigates temperature changes of the optical absorption edge of (NH4)2CuCl4·2H2O crystals in the region of the ferroelastoelectric (FEE) phase transition. The low-energy tail of the absorption edge in these materials shows an exponential shape. The temperature range above 200.5 K and below 100 K follows the empirical Urbach's rule. The obtained experimental data confirmed the existence of the FEE phase transition at 200.5 K. Nonfulfillment of Urbach's rule just below the phase transition temperature is explained by the scattering of light on the FEE domains. [ABSTRACT FROM AUTHOR]

Light emitting diodes (LEDs) structures based on p-GaN film/n-ZnO nanorods quasiarray heterojunction were fabricated. ZnO nanostructures were grown on the p-type GaN templates using two different methods. The turn-on voltages of ZnO/GaN heterojunctions based on ZnO nanorods grown using the gas-transport reaction and hydrothermal methods were equal to 3.2 V and 6.5 V, respectively. The diode-ideality factors were estimated to be of around 45 and 36 for the samples with ZnO nanorods grown using the method of the gas-transport reaction and the hydrothermal method, respectively. The large values of the ideality factors can be explained by a high density of trap states and quality of the contacts with the p - n junctions. The electroluminescence (EL) spectra of LEDs with ZnO nanorods grown by the gas-transport reaction and hydrothermal methods were approximated by four and three Gaussians, respectively. On the basis of the X-ray diffraction (XRD), electrical and optical studies data, one can conclude that the emission peaks at 389-391, 410-412, 436-438 and 502 nm correspond to the near-band-edge (NBE) recombination in ZnO, interface carriers recombination in ZnO/GaN junction, the electrons transition from GaN conduction band to Mg2+ doping level, and to the emission from the defect levels in ZnO, respectively. The LED based on ZnO nanorods synthesized using the hydrothermal method emitted a more pure ultraviolet (UV) light. [ABSTRACT FROM AUTHOR]

In this study porous silicon/graphene-based nanostructures were prepared by deposition of the graphene oxide and the reduced graphene oxide on the porous silicon layer. The charge transport in obtained structures was analyzed on the basis of temperature dependencies of the conductivity in the 12–300 K range within the model of disordered semiconductors. Hopping conductivity and activation mechanism of charge transport in different temperature ranges were established and the activation energy of the conductivity was determined. The deposition of the graphene and graphene oxide nanosheets on the porous silicon surface changes the limits of these ranges toward lower temperatures. The impedance spectra of PS/graphene-based structures were measured in the 25 Hz − 1 MHz frequency range in the wide temperature range. A decrease in electrical capacitance with increasing the frequency and an increase in impedance at lowering the temperature were revealed. [ABSTRACT FROM AUTHOR]

Gallium oxide has recently been identified as a promising scintillator. To assess its potential as a detector material for ionizing radiation at low temperatures, we measured the luminescence and scintillation properties of an undoped Ga2O3 crystal over the 7–295 K temperature range. The emission of the crystal is due to the radiative decay of self-trapped excitons and donor-acceptor pairs and peaks at a wavelength of 380 nm. The scintillation light output of the undoped Ga2O3 increases with a decrease in temperature, reaching a maximum value of 19 300 ± 2200 ph/MeV at 50 K. The measured luminescence kinetics has a recombination character with specific decay time (τ0.1) increasing from 1 to 1.8 μs at cooling. Since radiative decay in the crystal competes with nonradiative processes, material optimization could lead to the scintillator achieving a yield of 40800 ph/MeV, a figure considered to be an upper limit. [ABSTRACT FROM AUTHOR]

On the basis of spectroscopic studies of (NH2(C2H5)2)2CoCl4 crystals, the absorption bands corresponding to the internal electronic transitions in the Co2+ ion were identified. The values of the crystal field and Racah parameters were calculated. The temperature evolution of the absorption spectra of (NH2(C2H5)2)2CoCl4 crystals reveals the anomalies of their parameters at the points of phase transitions. The corresponding changes of the absorption spectra were discussed in terms of distortion of the metal-halogen complex. The temperature dependences of the absorption spectra of (NH2(C2H5)2)2CoCl4 crystals confirm the presence of the thermochromic phase transitions at 255 and 330 K. [ABSTRACT FROM AUTHOR]

Abstract: This study explores the phenomenology of zonally elongated transients (ZELTs) in the ocean and the sensitivity of their properties to changes in several environmental factors. ZELTs explain a major part of anisotropy in mesoscale turbulent flow. Calculations are performed in a two‐layer, quasi‐geostrophic model. Empirical Orthogonal Functions (EOF) decomposition allows for the separation of ZELTs from the background turbulent flow as several leading EOF modes. The leading Extended EOF reveals that ZELTs propagate westward at the speed of ∼ 1 cm s−1. The decrease in the planetary vorticity gradient and increase in the bottom drag coefficient each leads to flattening of the variance spectrum, isotropization of the leading EOF, and fast decay of the autocorrelation function of its corresponding Principal Component. [ABSTRACT FROM AUTHOR]

The results of the investigations of X-ray excitation spectra, thermostimulated luminescence and influence of light illumination on the thermoluminescence glow curves of Eu3+-doped Ca3-xCdxGa2Ge3O12 garnet polycrystalline samples are presented. It is shown that Ca3-xCdxGa2Ge3O12 polycrystalline samples are characterized by intrinsic luminescence, which consists of several components. The nature of intrinsic luminescence is discussed. It is suggested that the nature of thermoluminescence glow peak near 150 K is connected with the [(VGe+VO)--F+] associations formed under X-ray irradiation at 85 K. The influence of light illumination on the TSL intensity of the preliminary X-ray irradiated samples is shown. [ABSTRACT FROM AUTHOR]

This paper explores stability of and transport by baroclinic vortices on the β plane using a two-layer, quasigeostrophic model. The study adapts a wave-mean flow formalism and examines interactions between the axisymmetric flow ('the vortex') and residuals ('the waves'). Unlike baroclinically unstable vortices on the f plane, such vortices on the β plane can be also vulnerable to barotropic instability as revealed by the globally integrated energy balance analysis. The spatial structure of energy fluxes shows the energy leakage inside the vortex core when its breakdown occurs. Mixing by stable and unstable vortical flows is quantified through the computation of finite-time Lyapunov exponent (FTLE) maps. Depending on the strength of wave radiation, the upper-layer FTLE maps of stable vortices show either an annulus or volute ring of vigorous mixing inside the vortex interior. This ring region is disrupted when the vortex becomes unstable. Both stable and unstable vortices show the wavy patterns of FTLE in the near and far fields. Despite the fact that the initial vortex resides in the top layer only, significant FTLE patterns are observed in the deep layer at later times. Lagrangian analysis of the vortex-induced change of large-scale tracer gradient demonstrates significant effects of vortex instability in the top layer and the importance of the wavelike anomalies in the bottom layer. [ABSTRACT FROM AUTHOR]

We have obtained X-ray emission spectra of Ga and Ge in Ca3Ga2Ge4O14, X-ray emission OKα-spectra in Ca3Ga2Ge4O14, Ca3Ga2Ge4O14 + Ce3%, and Ca3Ga2Ge4O14 + Eu4% and Xray photoelectron spectra in Ca3Ga2Ge4O14 . Our X-ray spectral studies of the Ca3Ga2Ge4O14 gallogermanate have shown that the top of the valence band near the Fermi level is formed mainly by p states of gallium and germanium as well as p states of oxygen, whose intensity is sufficiently low. The middle of the valence band is formed by gallium 3d states with oxygen 2s states lying below them. These states are hybridized with 4p states of gallium and germanium because of which there are Kβ′′-satellites in the Kβ2-subbands of gallium and germanium. The bottom of the valence band is formed by 3d states of germanium, whose contribution to chemical bonding is insignificant. The X-ray emission bands of Ga and Ge in Ca3Ga2Ge4O14 and the photoelectron spectrum of the valence electrons of Ca3Ga2Ge4O14 are in good agreement. The OKα-band changes its fine structure only slightly upon doping Ca3Ga2Ge4O14 with Ce or Eu. The investigations of intrinsic luminescence under X-rays excitation of Ca3Ga2Ge4O14 gallogermanate are presented. [ABSTRACT FROM AUTHOR]

Gallium oxide has recently been identified as a promising scintillator. To assess its potential as a detector material for ionizing radiation at low temperatures, we measured the luminescence and scintillation properties of an undoped Ga2O3 crystal over the 7–295 K temperature range. The emission of the crystal is due to the radiative decay of self-trapped excitons and donor-acceptor pairs and peaks at a wavelength of 380 nm. The scintillation light output of the undoped Ga2O3 increases with a decrease in temperature, reaching a maximum value of 19 300 ± 2200 ph/MeV at 50 K. The measured luminescence kinetics has a recombination character with specific decay time (τ0.1) increasing from 1 to 1.8 μs at cooling. Since radiative decay in the crystal competes with nonradiative processes, material optimization could lead to the scintillator achieving a yield of 40800 ph/MeV, a figure considered to be an upper limit. [ABSTRACT FROM AUTHOR]

In the past centuries consumption of bread made of ergot-infected flour resulted in mass poisonings and miscarriages. The reason was the sclerotia of Claviceps purpurea (Fr.) Tul.-a source of noxious ergot alkaloids (ergotamine and ergovaline). The authors have searched the 19th century medical literature in order to find information on the following topics: dosage forms of drugs based on ergot and their application in official gynecology and obstetrics. The authors also briefly address the relevant data from the previous periods as well as the 20th century research on ergot. The research resulted in a conclusion that applications of ergot in gynecology and obstetrics in the 19th century were limited to controlling excessive uterine bleeding and irregular spasms, treatment of fibrous tumors of the uterus, and prevention of miscarriage, abortion, and amenorrhoea. The most common dosage forms mentioned in the works included in our review were the following: tinctures, water extracts (Wernich's and Squibb's watery extract of ergot), pills, and powders. The information documented in this paper will be helpful for further research and helpful in broadening the understanding of the historical application of the described controversial crude drugs. Ergot alkaloids were widely used in obstetrics, but in modern times they are not used in developed countries anymore. They may, however, play a significant role in developing countries where, in some cases, they can be used as an anti-hemorrhage agent during labor.

Stimuli-responsive carriers of pharmaceutical agents have been extensively researched in recent decades due to the possibility of distinctively precise targeted drug delivery. One of the potentially beneficial strategies is based on the response of the medical device to changes in the ionic environment. Fluctuations in ionic strength and ionic composition associated with pathological processes may provide triggers sufficient to induce an advantageous carrier response. This review is focused on recent developments and novel strategies in the design of ion-responsive drug delivery systems. A variety of structures i.e., polymeric matrices, lipid carriers, nucleoside constructs, and metal-organic frameworks, were included in the scope of the summary. Recently proposed strategies aim to induce different pharmaceutically beneficial effects: localized drug release in the desired manner, mucoadhesive properties, increased residence time, or diagnostic signal emission. The current state of development of ion-sensitive drug delivery systems enabled the marketing of some responsive topical formulations. Concurrently, ongoing research is focused on more selective and complex systems for different administration routes. The potential benefits in therapeutic efficacy and safety associated with the employment of multi-responsive systems will prospectively result in further research and applicable solutions.

Following the onset of the strong 2014-2016 El Niño, a decade-long increase of the basin-wide sea level and heat content in the subtropical southern Indian Ocean (SIO) in 2004-2013 ended with an unprecedented drop, which quickly recovered during the weak 2017-2018 La Niña. Here, we show that the 2014-2016 El Niño contributed to the observed cooling through an unusual combination of both the reduced heat advection from the Pacific (dominant in the eastern SIO) and the basin-wide cyclonic wind anomaly that led to shoaling of isotherms (dominant in the western SIO). The ensuing recovery was mainly forced by an anticyclonic wind anomaly associated with stronger trade winds that caused deepening of isotherms and upper-ocean warming, effectively suppressing the 2014-2016 cooling signal propagating from the eastern boundary. The results presented here highlight the complexity of the SIO heat content variability driven by remote and local forcing., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)