Charge transfer transitions in the photoluminescence spectra of Zn1-xMexO (Me = Mn, Ni, Co) oxide compounds

Crystals of Zn1-xCoxO and Zn1-xNixO are studied by photoluminescence at temperatures of 8 and 90 K. By resolving the spectra into sums of gaussian distributions and using the known positions of donor and acceptor levels of 3d-impurities relative to the edges of the allowed bands, the observed peaks in the photoluminescence spectra are interpreted in terms of radiative recombination through donor and acceptor levels of nickel and cobalt ions. These results are compared with previously observed features of the photoluminescence spectra of Zn1-xMnxO crystals. © 2013 American Institute of Physics

Manifestation of quasi-biennial oscillation in ozone vertical distribution

The quasi-biennial oscillations (QBO) in ozone and temperature vertical distributions are studied on the basis of ozonesonde data of 21 stations. Maximum QBO amplitudes in ozone are noted in the 16-20 kn layer over Resolute (75N), Aspendale (38S) and in the northern mid-latitude band, but in the 20-24 km layer in the northern subtropical band. In the upper layers the QBO effect is less evident. In the tropospheric layer it is difficult to note the QBO-related effect in all the groups of the data. In all the layers where the QBO effect is noted the positive deviations precede, but the negative deviations follow the time of maximum of the easterly equatorial wind at 50 mb level. No essential differences in phase or amplitude characteristics of the ozone QBO were noted for the Aspendale data compared with that for the Northern Hemisphere data. The QBO-effect is not noted in the temperature data in the mid-latitudes. Above Resolute and in subtropics the ozone and temperature effects are roughly in phase each with other, except in the 28-32 km layer over subtropics, where they are opposite each to other

Quasi-biennial oscillation in total ozone: Global behaviour derived from ground-based measurements

The quasi-biennial oscillation (QBO) in total ozone (TO) is studied on the basis of TO measurements at the world ground-ased ozone network during 1972-1988. The TO content is on the whole greater in the tropical belt and smaller in high latitudes during the westerly phase of the QBO of the equatorial stratospheric 50 mb wind than during the easterly phase in all seasons. The appropriate TO difference (westerly category minus easterly category) displays certain space structures changing during a year. There are regions with the peculiar annual evolution of this difference, particularly in the Arctic and Antarctic. Spectral analysis reveals bimodality of TO power spectra in the frequency range of QBO periods, with spectral maxima corresponding to 17-23 months and 28-35 months. The large period oscillations are predominant on the whole. The small period oscillations are likely the consequence of interaction between an annual cycle and QBO

The effect of the solar rotational irradiance variation on the middle and upper atmosphere calculated by a three-dimensional chemistry-climate model

This paper analyzes the effects of the solar rotational (27-day) irradiance variations on the chemical composition and temperature of the stratosphere, mesosphere and lower thermosphere as simulated by the three-dimensional chemistry-climate model HAMMONIA. Different methods are used to analyze the model results, including high resolution spectral and cross-spectral techniques. To force the simulations, an idealized irradiance variation with a constant period of 27 days (apparent solar rotation period) and with constant amplitude is used. While the calculated thermal and chemical responses are very distinct and permanent in the upper atmosphere, the responses in the stratosphere and mesosphere vary considerably in time despite the constant forcing. The responses produced by the model exhibit a non-linear behavior: in general, the response sensitivities (not amplitudes) decrease with increasing amplitude of the forcing. In the extratropics the responses are, in general, seasonally dependent with frequently stronger sensitivities in winter than in summer. Amplitude and phase lag of the ozone response in the tropical stratosphere and lower mesosphere are in satisfactory agreement with available observations. The agreement between the calculated and observed temperature response is generally worse than in the case of ozone

Total ozone and total NO2 latitudinal distribution derived from measurements in the Atlantic Ocean in May 1988

Total ozone and NO2 were measured aboard a ship in the 40S - 40N latitude band in the Atlantic Ocean in the second half of May 1988. The main features of the latitudinal distributions of total NO2 and ozone are similar. There is seen an increase of total ozone and NO2 from the tropical to subtropical latitudes, strongest in the region of the subtropical jet stream. The fine structure has been revealed in the total ozone and NO2 latitudinal distributions, connected most likely with stratosphere-troposphere exchange processes in the tropopause folding zone

Monkeypox and other orthopoxvirus zoonoses

The paper highlights the current knowledge on infection biology, epidemiology and evolution of monkeypox virus (MPXV), cowpox virus (CPXV), buffalopox virus (CPXV), camelpox virus (CMLPV), as well as addresses some factors that modulate dynamics of orthopoxvirus transmission, manifestation of orthopoxvirus infections and their preservation in nature. Despite the elimination of the historically infamous smallpox, orthopoxviruses remain a serious veterinary and health problem. Their role is currently increasing while the number of persons not immune to smallpox grows. Along with this, there is a genetic transformation of pathogens. In this regard, the risks of human infection with orthopoxviruses of zoonotic nature are increasing. The problem of monkeypox, cowpox, buffalopox and camelpox and the respective agents included in the genus of zoonotic orthopox viruses presents the greatest interest. Along with the increased number of human monkeypox cases in 2020–2022, a retrospective analysis of the last 20 years shows that the activity of monkeypox outbreaks in the XXI century intensified in Central African countries. Cowpox outbreaks in Europe and camelpox outbreaks in Southwestern and Central Asia have also become more active. In 2011, in India, the camelpox virus overcame the interspecies barrier and caused a clinical pox-like disease in humans. Scientists are alarmed by these facts as the camelpox virus genomeis 99% homologous to the genome of the small poxvirus. This requires strengthening the epizootological and epidemiological monitoring of orthopoxvirus zoonotic pathogens

EMR searching of quantum behavior of magnetic γ-Fe<inf>2</inf>O<inf>3</inf> nanoparticles encapsulated into poly(Propylene imine) dendrimer

© Kazan Federal University (KFU).The superparamagnetic γ-Fe2O3 nanoparticles (average diameter of 2.5 nm) encapsulated in poly(propylene imine) dendrimer have been investigated by electron magnetic resonance (EMR). EMR measurements have been recorded in perpendicular and parallel configurations in the wide temperature range (4.2-300 K). It has been shown that the model based on the spin value S = 30, corresponding to the total magnetic moment of the nanoparticle, can be used to interpret the experimental results and the proof of the quantum behavior of γ-Fe2O3 nanoparticles

Galkhaita

Los análisis de Gal-Khaya y Khaidarkan dieron, respectivamente, Hg 47,60, 49,02; Cu 3,49, 2,85; Zn 3,00, 0,60; Fe 0,31, nada ; Tl 0,46, 2,90; As 23,60, 19,49; Sb 0,59, 5,51; S 21,00, 19,31; Se 3 ppm, 150 ppm; total 100,05, 99,695 %.(...

Mössbauer study of the surface of core-shell type nanoparticles

© 2016, Pleiades Publishing, Ltd.The properties of the surface layer of core-shell nanoparticles incorporated into the matrix of macromolecules of 3,4-bis(decyloxybenzoyl) poly(propylene imine) derivative of the second generation are studied by Mössbauer spectroscopy at low temperatures. The spin states, the details of the phonon spectrum and the Debye temperature of surface layer atoms discussed

Blue shift in optical absorption, magnetism and light-induced superparamagnetism in γ-Fe2O3 nanoparticles formed in dendrimer

© 2015, Springer Science+Business Media Dordrecht. Abstract: We are presenting the investigation of the optical, magnetic, and photoinduced superparamagnetic properties of single-domain γ-Fe2O3 nanoparticles (NPs) with diameters of about 2.5 nm formed in second-generation poly(propylene imine) dendrimer. The optical absorption studies indicated direct allowed transition with the band gap (4.5 eV), which is blue shift with respect to the value of the bulk material. Low-temperature blocking of the NPs magnetic moments at 18 K is determined by SQUID measurements. The influence of pulsed laser irradiation on the superparamagnetic properties of γ-Fe2O3 NPs was studied by EPR spectroscopy. It has been shown that irradiation of the sample held in vacuo and cooled in zero magnetic field to 6.9 K leads to the appearance of a new EPR signal, which decays immediately after the irradiation is stopped. The appearance and disappearance of this new signal can be repeated many times at 6.9 K when we turn on/turn off the laser. We suppose that the generation of conduction band electrons by irradiation into the band gap of the γ-Fe2O3 changes the superparamagnetic properties of NPs. Graphical Abstract: [Figure not available: see fulltext.]Features of the behavior of single-domain γ-Fe2O3 nanoparticles formed in dendrimer were found by UV-Vis and EPR spectroscopy: “blue” shift in optical absorption, a significant increase in the band gap width and variation of superparamagnetic properties under light irradiation