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Recently, progress has been made in fabricating diamond-based scintillators with integrated rare-earth luminescent particles. These luminescent particles are integrated into the bulk of diamond during their synthesis by chemical vapor deposition (CVD). However, the growth conditions include a chemically aggressive plasma environment and elevated temperatures, which results in the partial degradation of particles and a decrease in the intensity of their luminescence. Here, we investigate the effect of thermal annealing of luminescent EuF3 and SrF2:Eu powders in microwave plasma that simulates the growth conditions of polycrystalline diamond. It was found that silicon substrates act as efficient reducing agents that lead to the partial reduction of trivalent europium to divalent europium. When annealing occurs on a diamond substrate, the reduction processes proceed at a significantly slower rate. The observed luminescence spectra showed both Eu2+ and Eu3+ luminescence bands, which allows for a targeted tuning of the luminescence spectrum of europium in composites and can be used to fabricate detectors and visualizers of X-ray radiation using a visible signal from the desired combination of Eu2±/Eu3± ions. During plasma annealing in pure hydrogen at moderate temperatures (600 °C), an intensive hydrogenation of particles is observed. Such hydrogen plasma treatment of fluorides may be considered a promising route to fabricate hydrides of various metals. [ABSTRACT FROM AUTHOR]

Results of lidar observations at a wavelength of 532 nm in Obninsk over the period from 2012 to 2021 are presented. In 2014–2018 the stratosphere aerosol was in a state close to the background. In 2019, aerosol maxima were observed in the 15–30 km layer associated with the eruptions of the Ambae and Raikoke volcanoes. The seasonal behavior of the integral backscattering coefficient in the background period is presented. In the lower layer of the stratosphere of 13–23 km, an increase in backscattering was observed in the second half of the year, associated with an increase in the number of natural fires. In the 23–30 km layer, the maximum backscattering was observed in summer. It was found that the contribution of the lower layer of 10–15 km to the optical thickness of the entire layer of 10–30 km is on average 61%. This implies the need to take into account the aerosol of the lower layer of 10–15 km in the overall balance of stratospheric aerosol in chemical–climatic models of the stratosphere. In the second half of the year, aerosol of natural fires is often observed in the 10–15 km layer. In some episodes, the addition of natural fire aerosol to an optical layer thickness of 10–30 km with respect to the spherical sulfuric acid aerosol ranges from 50 to 150%. At the same time, in annual mean terms, this additive in 2014–2021 on average was only 10%. In the last 5 years, there has been a trend towards an increase in the content of aerosol from natural fires, but so far the content of sulfate aerosol in the stratosphere remains predominant. [ABSTRACT FROM AUTHOR]

We present the observations of stratospheric aerosol layers at the Roshydromet lidar stations in St. Petersburg (59.9° N), Obninsk (55.1° N), and Znamensk (48.6° N) a few months after the explosive eruption of the submarine Hunga Tonga (21° S, 175° W) volcano in January 2022. Aerosol layers with the backscattering ratio from 1.2 to 1.4 at altitudes from 20 to 24 km were observed in April, May, and October. The depolarization degree at a wavelength of 532 nm and the ratio of the backscattering coefficients at 355 and 532 nm wavelengths show that aerosol was composed of spherical submicron particles. The observations are compared with the known literature data on Hunga Tonga aerosol propagation. [ABSTRACT FROM AUTHOR]

An analysis of variations in the height-integrated stratospheric ozone content in layers of 13–18, 18–23, and 23–30 km according to the data of lidar and satellite measurements in 2014–2022 over the city of Obninsk (55.1° N, 36.6° E) is presented. The simulation of interannual ozone variations for individual quarters of the year is carried out using the method of multiple linear regression. Quasi-biennial oscillations (QBO) of the equatorial wind, Arctic oscillation (AO), El Niño Southern Oscillation (ENSO), solar activity (SA), volcanic aerosol (VA), and polar stratospheric clouds (PSC) are considered as influencing factors. An increase in the ozone content is observed in the eastern phase of QBO in the altitude range of 18–30 km (I–II quarter) and in the western phase of QBO within the interval of 13–23 km (IV quarter). In separate layers, significant influences of AO (II–III quarters), SA (I–II quarter), and VA (III–IV quarters) are found. The PSC influence during the year manifests itself first in II quarter in the layer of 13–18 km, and then in IV quarter in the layer of 13–23 km. Possible physical mechanisms underlying the observed correlations are considered. [ABSTRACT FROM AUTHOR]

A study was carried out on the effect of a heavy chlorine atom introduced into the aromatic fragment of a 1,3-diketone ligand in Eu3+ coordination compounds on the spectral and luminescent properties of complex compounds. The data obtained from the absorption, optical excitation, fluorescence, and phosphorescence spectra as well as from the kinetics of the luminescence intensity permit estimation of the efficiency of energy transfer processes within the compounds studied. Introduction of a heavy chlorine atom was found to raise the energy of the first excited singlet state from 24,500 to 26,000 cm–1 but not affect the energy of the triplet level of the ligand. Furthermore, introduction of a chlorine atom leads to a decrease in the nonradiative relaxation constant (from 1290 to 840 s–1) and thereby triples the luminescence quantum yield from 23 to 64%. Hence, a new approach for the rational construction of useful coordination compounds of Eu3+ ions with 1,3-diketone ligands has been developed consisting of the substitution of a hydrogen atom by a heavy chlorine atom in the aromatic fragment of the ligand. [ABSTRACT FROM AUTHOR]

Learning and behavior were more sensitive than LTP-like plasticity to blockade of NMDA receptors (NMDAr). I.p. and intraventricular injections of low, non-toxic doses of the non-competitive NMDAr antagonist MK-801 did not block LTP in the hippocampus but impaired hippocampus-dependent forms of learning and spatial behavior in both allo- and egocentric coordinate systems and prevented the reproduction of previously developed reactions in well-trained animals. Our results do not support the notion that there is an association between LTP-like plasticity and spatial learning. [ABSTRACT FROM AUTHOR]

The reaction of 4,4,5,5,6,6,6-heptafluoro-1-(1-methyl-1H-pyrazol-4-yl)hexane-1,3-dione (HPyrC3F7) with freshly precipitated hydrated europium(ɪɪɪ) and samarium(ɪɪɪ) hydroxides in EtOH afforded crystalline complexes of the composition [Ln(PyrC3F7)3(EtOH)2], the features of their formation depending on the stoichiometric ligand/metal ratios were studied. The structure and composition of the complexes were characterized by physicochemical methods, including single-crystal X-ray diffraction. The luminescent properties of these compounds in the crystalline state and in solutions were studied in detail. Possible ways of transferring electronic excitation in the complex [Eu(PyrC3F7)3(EtOH)2] were considered. [ABSTRACT FROM AUTHOR]

The results of aerosol backscattering sounding at two wavelengths of 355 and 532 nm in the lower mesosphere at Rosgydromet lidar stations from 2012 to 2021 are presented. A significant increase in the backscattering ratio R has been observed in the altitude range 50–70 km since 2018. In 2019–2020, the average R attained 1.25 at an altitude of 70 km. The Rayleigh measurements at 532 nm overestimated the temperature by up to +20 K in that period. The two-wavelength temperature measurement technique eliminates this error. [ABSTRACT FROM AUTHOR]

Multiple scattering arising in cirrus clouds in the process of lidar sensing of the atmosphere is studied using the Monte Carlo method. The calculations are performed for model scattering phase functions corresponding to crystalline cirrus cloud particles with sizes from 20 to 100 µm. A critical analysis of some common methods for multiple scattering correction in cirrus clouds is carried out. Numerical experiments on sensing cirrus clouds and stratospheric aerosol from the Earth's surface with signal calibration at an altitude of 30 km are conducted. It is shown that ignoring the multiple scattering in this measurement scheme leads to a considerable distortion of the altitude profile of the backscattering coefficient in cirrus clouds and above them; at the same time, errors in the determination of the optical thickness of the clouds remain insignificant. An iteration scheme for taking into account multiple scattering is proposed and tested in numerical experiments. The simulation results are compared with experimental data. [ABSTRACT FROM AUTHOR]

An analysis of lidar observations at wavelengths of 532 and 355 nm conducted in the layer 13–23 km over Obninsk (55° N) from 2014 to 2018 has revealed the effect of solar activity factors on stratospheric aerosol. The time interval from 2016 to 2018 is characterized by a decrease in aerosol backscattering by a few percent 0 to 2 days after the commencement of Forbush decreases in the galactic cosmic ray flux. In 2014–2017, solar proton events with a delay of 3–8 days are followed by an increase of 20% to 70% in aerosol backscattering. This effect has been shown to occur predominantly during the transport of stratospheric air to the observation point from the region of high latitudes. [ABSTRACT FROM AUTHOR]

Ionothermal synthesis of carbon nitride paved the way to a new structural allotrope—polytriazine imide. In this work, we screen available precursors for pristine polytriazine imides and for their graphitic analogs narrowing it to the melamine—urea mixture as the most promising starting material. Photocatalytic activity of materials verified in reaction of benzyl alcohol oxidation to benzaldehyde, which is known to be highly requested chemical with thousands of tons of annual production. Therefore "green" and selective route of production is highly desired. Developed PTI-LiCl was tested for selective photooxidation of benzyl alcohol to benzaldehyde, demonstrating precious conversion and selectivity rates—96.3% and 91.6%, respectively after 5 hours of UV irradiation. Detailed physical-chemical characterization revealed that PTI materials possessed more ordered and highly condensed structure which grant them improved photocatalytic properties in comparison to graphitic carbon nitride polymorph. Graphical abstract represents two different lines of materials which are known to be various polymorphs of carbon nitride studied comparatively in the present work. One of them is convenient graphitized carbon nitride which is prepared from precursors (melamine, urea or thiourea) via the simple thermal treatment. Another line of materials are prepared via thermal treatment in the eutectic mixture of molten salts. The later line of materials is more active in selective photocatalytic oxidation of benzyl alcohol. [ABSTRACT FROM AUTHOR]

We present the results of study of the 2D distribution of galaxies in galaxy clusters with redshifts in rich regions. Our data consists of two sets extracted from "The Catalogue of Galaxy Groups and Clusters" (Panko and Flin). The first data set contains 460 galaxy clusters with richness 100 and more galaxies in the cluster field, the second one contains 112 galaxy clusters belonging to superclusters with multiplicity 5 and more members. The "Cluster Cartography" tool was specially designed for studying the inner structure of galaxy clusters. We detected different kinds of regular substructures, such as crossing and divaricating filaments (X and Y-type peculiarities), curved strips and short compact chains in the galaxy clusters in both our data sets. Founded peculiarities can be considered as a result of the formation of galaxy cluster at the intersection of DM filaments or filament-wall interaction. It is confirmed by the types of alignment of galaxies in the substructures. We also found the alignment of substructures in galaxy supercluster members accordingly to the direction to the nearest neighbor. [ABSTRACT FROM AUTHOR]

We present the observations of stratospheric aerosol at Rosgidromet lidar stations after the explosive eruption of the Raikoke volcano (Kuril Islands, 48.29° N, 153.25° E) in June 2019. The forward trajectory analysis and observations by the CALIOP lidar onboard the CALIPSO satellite were used to track how the aerosol trace in the stratosphere propagated from the volcano around the pole toward Western Siberia within a month after the eruption. We presented the lidar measurements of volcanic aerosol from late July 2019 at the Rosgidromet lidar stations in Obninsk, Znamensk, Novosibirsk, and Petropavlovsk-Kamchatsky. Volcanic aerosol was observed in the layer from 13 to 18 km. The integrated backscattering coefficient in the layer varied from a maximum of (0.8–1.6) × 10−3 sr−1 in August–September 2019 to (0.2–0.3) × 10−3 sr−1 toward the end of the year. [ABSTRACT FROM AUTHOR]

This study is devoted to the development of efficient luminescent hybrid materials excited by UV radiation and featuring narrow luminescence lines as well as light, humidity, and temperature resistance. As a luminescent material, a terbium ion coordination compound introduced into the matrix of an organofluorine polymer is used. It has been shown that efficient excitation transfer to electronic levels of the terbium ion can be achieved by proper ligand selection. The polymer matrix material does not affect the luminescence properties of the Tb(III) coordination compound. [ABSTRACT FROM AUTHOR]

Depression in the biological models considered here can be split into two opposite patterns of changes in serotonin and dopamine levels, corresponding to passive and active stress response tactics [Selye, 1979] – ↑5HT, ↓DA and ↓5HT, ↑DA. Unavoidable pain stimulation, chronic moderate aversive stimulation, unavoidable social suppression, and learned helplessness in response to social defeats are characterized by the ↑5HT, ↓DA pattern. Aggressive behavior to an intruder, avoidance of an aggressive inhabitant, avoidance of pain stimulation, and injection of ketamine all activate the ↓5HT, ↑DA pattern. The physiological nucleus of learned helplessness and social avoidance may be the Pavlovian conditioned freezing reflex in response to a threat and the conditioned avoidance reaction, respectively. Further studies should address the following questions: how does neuron activity in the raphe nuclei change during forced swimming? Why does the increase in the serotonin level in response to antidepressants increase swimming while serotonin neurons are inhibited during swimming? Why is the increase in the serotonin level in the state of learned helplessness combined with suppression of active swimming? [ABSTRACT FROM AUTHOR]

The results of the study of the degradation of thermoluminescent materials Li2B4O7:Be + Mn and Li2B4O7:Zn + Mn under the effect of radiation (pulsed electron beam) and laser radiation are presented. As a result of exposure to high doses of radiation, the structure of the samples under study partially acquires an amorphous character, while the effect of radiation exposure is manifested in the optical properties in the appearance of green luminescence due to manganese centers in the tetrahedral environment. With subsequent irradiation with a laser at a wavelength of 350 nm, luminescence centers decay due to photochemical oxidation of manganese by the reaction of Mn2+ → Mn3+. It is shown that Li2B4O7:Be + Mn has a lower radiation resistance than Li2B4O7:Zn + Mn. [ABSTRACT FROM AUTHOR]

We present the results of two-wavelength lidar sensing of the middle atmosphere in the altitude range from 30 to 60 km over Obninsk (55.1° N, 36.6° E) in 2012–2017. Monthly average values of the ratio of aerosol and Rayleigh backscattering coefficients (RARC) at a wavelength of 532 nm, averaged over the layers of 40–50 km and 50–60 km, vary from 0 to 0.02, while the average peak RARC levels in these layers vary from 0.1 to 0.2. Short-term (shorter than 1 month) and long-term (half-year and longer) variations in backscattering are observed. Short-term variations are time concurrent with the occurrence of meteor showers. Long-term enhancements of backscattering in the layer of 50–60 km were observed in 2013 after the Chelyabinsk meteorite fall, as well as in the first half of 2016. In 2014–2015, the monthly average RARC was zero within measurement errors at altitudes from 40 to 60 km. We analyzed the possibility for meteoric aerosol to manifest in backscattering, taking into account the fluxes of meteoric material, gravitational sedimentation of aerosol, and the effect of vertical wind. The flux of visible meteors with masses larger than 10−6 kg and bolides is shown to be insufficient for a long-term enhancement of backscattering in the layer of 50–60 km. It is hypothesized that the enhancement in backscattering is most likely to be due to the occurrence of an enlarged fraction of meteoric smoke particles, formed by ablation of radio meteors and penetrating into the upper stratosphere in the region of the stratospheric polar vortex. In early 2016, this was favored by the formation of an extremely strong stratospheric polar vortex and its shift toward Eurasia. [ABSTRACT FROM AUTHOR]

Radiotherapy for head and neck cancers commonly causes damage to salivary gland tissue, resulting in xerostomia (dry mouth) and numerous adverse medical and quality-of-life issues. Amifostine is the only Food and Drug Administration-approved radioprotective drug used clinically to prevent xerostomia. However, systemic administration of amifostine is limited by severe side effects, including rapid decrease in blood pressure (hypotension), nausea, and a narrow therapeutic window. In this study, we demonstrate that retroductal delivery of amifostine and its active metabolite, WR-1065, to murine submandibular glands prior to a single radiation dose of 15 Gy maintained gland function and significantly increased acinar cell survival. Furthermore, in vivo stimulated saliva secretion was maintained in retrograde-treated groups at levels significantly higher than irradiated-only and systemically treated groups. In contrast to intravenous injections, retroductal delivery of WR-1065 or amifostine significantly attenuated hypotension. We conclude that localized delivery to salivary glands markedly improves radioprotection at the cellular level, as well as mitigates the adverse side effects associated with systemic administration. These results support the further development of a localized delivery system that would be compatible with the fractionated dose regimen used clinically. [ABSTRACT FROM AUTHOR]

Data of stratospheric ozone measurements with the AK-3 lidar over Obninsk in 2012-2015 are compared with Aura/MLS and Aura/OMI satellite data and parallel surface observations of total ozone (TO) with the Brewer spectrophotometer. The maximum difference in mean ozone concentration between the lidar and Aura/MLS data in the altitude range of 13 to 32 km does not exceed 0.2 x 1012 mol./cm3 (or the maximum of 9% at the altitude of 13 km). At the same time, Aura/OMI data have a positive bias of about 20% relative to lidar data in the range of 13 to 20 km that is associated with OMI measurement errors according to literature data. Total ozone values calculated from lidar measurements jointly with the known climatology data are compared with those measured with the Brewer spectrophotometer. It is demonstrated that the correlation between the results of measurements obtained by two methods is close to linear, and the mean relative difference in the overall measurement range does not exceed 5%. [ABSTRACT FROM AUTHOR]

We study the influence of bonding Sc(III) ion with 1,3-diketonate ligands on luminescent properties of 1,3-diketones in two complexes by means of optical spectroscopy. We show that the sensitization of the ligand luminescence of the complexes obtained increases from 0.8% for neat ligands and to 4% for the synthesized compounds; this fact is confirmed by the quantum yield measurements. [ABSTRACT FROM AUTHOR]

The results of lidar measurements of ozone profiles over Obninsk in the altitude range of 12-35 km in 2012-2016 are presented. Temporal variations in total ozone in the above altitude range and seasonal variations in the vertical distribution of ozone are considered. Basic attention is paid to the analysis of ozone profile variations on the daily and weekly scales. The backtrajectory analysis demonstrated that in most cases the formation of layers with low or high ozone values is explained by the direction of meridional advection. Cross-correlation coefficients for the variations in ozone and temperature relative to the current monthly mean variations are calculated. Rather high values of correlation coefficients (~0.4-0.6) are obtained for summer in the low stratosphere (100 and 160 hPa) and for winter in the upper troposphere (50 and 20 hPa). In general, variations in ozone profiles are consistent with available climatologic data. [ABSTRACT FROM AUTHOR]

A technique of probe photoluminescence and Raman spectroscopy has been developed. This technique makes it possible to detect small (10 to 10 g) amounts of uranyl compounds at short exposure times (1−10 s). The photoluminescence spectra of Na[UOCH(COO)] polycrystals recorded upon excitation by short-wavelength radiation of LEDs and lasers are found to contain equidistant bands with a shift of 854 cm, which corresponds to the frequency of totally symmetric uranyl vibration also manifesting itself in Raman spectra. [ABSTRACT FROM AUTHOR]

Lidar polarization measurements of stratospheric aerosol were performed over Obninsk in 2012-2015. In all, over 300 altitude profiles of the aerosol backscattering coefficient at a wavelength of 532 nm in the altitude interval from 10 to 40 km were obtained. Overall, the measured aerosol backscattering characteristics are close to the known background values. During spring 2013, an elevated content of spherical-type aerosol was noted in the tropopause region, seemingly associated with sedimentation of aerosol structures formed during the fall of the Chelyabinsk meteorite. In July 2014 and 2015, layers of increased aerosol scattering were observed in the altitude interval from 10 to 15 km, associated with transcontinental transport of aerosol from Canadian forest fires. Integrated backscattering and extinction characteristics are estimated for the lower (from tropopause level to 15 km) and middle (from 15 to 30 km) stratospheric layers. It is found that the contribution of the lower layer to these optical characteristics is 1.8 and 1.6 times larger than the contribution of the middle layer. [ABSTRACT FROM AUTHOR]

The design and operating principle of an active-current three-phase measuring transducer based on differentiating induction-current transducers without using integrated filters are considered. The dependence of the measurement accuracy of the active component of load current of a synchronous generator on the value of EMF of a differential induction-current transducer is determined. A scheme of computer simulation of a three-phase measuring transducer of active current is described. The results of computer simulation and experimental studies of the device confirming the ability of the transducer under consideration to replace the traditional solutions based on current transformers for marine electric-power systems are presented. [ABSTRACT FROM AUTHOR]

The photoluminescence spectra of sodium uranyl acetate polycrystals are recorded under excitation by different sources (semiconductor light-emitting diodes, cw lasers, and repetitively pulsed lasers). The excitation wavelengths fall into the absorption band of this solid, which makes it possible to record photoluminescence beginning from an extremely small volume of the material (10 cm) at exposures of ~10 s. [ABSTRACT FROM AUTHOR]

It has been suggested that hippocampal neurons activated via the neocortex by a novel stimulus during waking and storing memories of the stimulus must undergo repeated activation during sleep in order for the neocortex to form the corresponding permanent memory trace. This impelled us to study the possibility that reverberation of excitation occurs in neural networks connecting the hippocampus and the entorhinal cortex. Double and triple responses to single-pulse stimuli applied to Schaffer collaterals with previously potentiated synapses were recorded in the proximal part of field CA1 in the dorsal hippocampus in sleeping rats. Analysis of the latent periods of repeated responses suggested that the wave of excitation initiated in hippocampal field CA1, returning directly from the entorhinal cortex to the recording zone in field CA1 via fibers of the perforant pathway and also via field CA2, may again elicit discharges in field CA1 neurons, though not those which had been activated initially on stimulation of Schaffer collaterals. Thus, the neuronal circuits connecting the hippocampus and entorhinal cortex do not mediate reactivation of 'trained' neurons during subsequent sleep periods. [ABSTRACT FROM AUTHOR]

The nonlinear optical response of a colloidal solution of planar CdSe semiconductor nanocrystals (nanoplatelets) is studied for the first time. The nonlinear optical response of these nanoparticles is compared to that of spherical CdSe nanocrystals (quantum dots). The photoinduced nonlinearity is attributed to the optical generation of long-lived charge carriers in the nanoobjects under study. It is shown that, upon the exposure of a cell with the solution of nanoparticles to focused continuous-wave (cw) laser radiation with a wavelength of 473 nm, the nonlinear optical responses of CdSe nanoplatelets and quantum dots are somewhat different at identical optical densities at the above-indicated wavelength. The differences are supposedly associated with a higher diffusion rate of spherical nanoparticles in the solution because of their smaller size compared to that of nanoplatelets. [ABSTRACT FROM AUTHOR]

Altitude profiles of temperature of the middle atmosphere (30-60 km) are determined from data of lidar sensing at wavelengths of 355 and 532 nm using a modified Rayleigh method. Temperature disturbances are discriminated against the background of average profiles, using a smoothing spline. The altitude profiles of the potential energy density of gravity waves are calculated directly according to temperature fluctuations. A continuous wavelet analysis is used to determine the spectral characteristics of wave disturbances, including local power spectra of temperature fluctuations and potential energy, as well as vertical phase velocity and period for extracted wavelengths. The developed software tools make it possible to determine the characteristics of the wave disturbances localized in time and identified with respect to wavelengths of wave disturbances (wave packets). Lidar measurements in Obninsk are described. [ABSTRACT FROM AUTHOR]

Studies of the correlation between neuron activity and behavior require objective measurement of animal movement. This is obtained using video recordings followed by analysis of video images. The conditions for recording neuron activity in a Morris basin require the video camera to be positioned at an angle to the water surface, which leads to perspective distortion of the images and, as a result, errors in trajectory analysis. In the present study we present a method for correcting perspective distortions. [ABSTRACT FROM AUTHOR]

Aerosol lidar sensing of the middle atmosphere (30-65 km) was carried out in Obninsk over a year. The sensing at two wavelengths of 355 and 532 nm enabled the separation of Rayleigh and aerosol scattering contributions in lidar signals. Increased aerosol content is found within the 60-65 km altitude range. Monthly average lidar sensing data are compared with measurements of the radio meteor echo in Obninsk and Kollm (Germany). The correspondence between the time variations in the data of two types is revealed, which indicates the meteor origin of the aerosol. Possible physical causes of the appearance of the aerosol layer observed are discussed. [ABSTRACT FROM AUTHOR]

The technique for recording Raman spectra in uranium compounds using a probe minispectrometer with a multielement radiation detector has been developed. A selective filter, which reflects exciting laser radiation and transmits Raman signals, has been used to suppress the exciting radiation. It is shown that the technique developed makes it possible to record Raman spectra from a small amount (~10 g) of sodium uranyl-acetate polycrystals in a wide spectral range for several seconds. [ABSTRACT FROM AUTHOR]

In late December 2012 a blocking anticyclone followed by the event of minor stratospheric warming, set in the troposphere over West Siberia and, after that, over the European part of Russia. As a result of the deformation of a polar stratospheric vortex, the temperature in the lower stratosphere over Obninsk dropped below the threshold of the formation of polar stratospheric clouds. The lidar measurements of temperature, ozone values, and aerosol characteristics in the middle atmosphere were carried out at the lidar station during this atmospheric event. In three cases, polar stratospheric clouds (PSCs) referred to NAT I type according to the sounding results, were registered at the height of about 20 km. No considerable decrease in the ozone concentration in the area of PSC formation was revealed in these measurements. [ABSTRACT FROM AUTHOR]

We calculate the microphysical characteristics of stratospheric aerosol from lidar-sensing data at wavelengths of 355 and 532 nm using a priori information about the aerosol spectra obtained from balloon and aircraft measurement data. We analyze the mode structure of the spectra and its coupling with the integral microphysical characteristics of aerosol. For most implementations, it was shown that two aerosol modes (of background and volcanic natures) make commensurate contributions to integral aerosol characteristics, which makes it difficult to use the traditional method of model estimates. It is more efficient to use an optical model of a statistical character that is based on approximation dependences between the required integral aerosol characteristics and lidar-measured optical characteristics. We found that the area, volume, and effective size of particles and the lidar ratio at a wavelength of 355 nm correlated with the absolute values of backscattering coefficients at wavelengths of 355 or 532 nm and the lidar ratio at the wavelength of 532 nm correlated with the ratio of backscattering coefficients at these wavelengths. We estimate the error in the determination of integral characteristics of aerosol using the model developed. The model efficiency is demonstrated on real data of stratospheric aerosol lidar sensing. [ABSTRACT FROM AUTHOR]

It is suggested that information on new stimuli from the neocortex is transmitted to the hippocampus, where temporal traces persist in the form of mosaics of modified synapses. During sleep, populations of neurons storing these traces are reactivated and return the information required for consolidation of a permanent memory trace to the neocortex. A possible mechanism for the reactivation of 'trained' hippocampal neurons during memory consolidation consists of the reverberation of excitation in the neuron circuits linking the hippocampus and entorhinal cortex. Our studies in rats included recording of responses in hippocampal field CA1 to stimulation of Schaffer collaterals with potentiated synapses during waking and sleep. During deep sleep, discharges of field CA1 neurons were followed by waves of excitation which passed through the entorhinal cortex and reached the hippocampus and dentate gyrus via fibers of the perforant path, evoking neuron discharges in the latter. Repeated neuron discharges in field CA1 occurred on interaction of the early excitation wave returning directly via perforant path fibers and the late wave returning via Schaffer collaterals, not via the trisynaptic path via the dentate gyrus and hippocampal field CA3 but probably via field CA2. [ABSTRACT FROM AUTHOR]

We revised our hypothesis that the absence of motor behavior impairments at the presymptomatic stage of Parkinsonism, when degeneration of nigrostriatal dopaminergic neurons has already occurred, is the result of compensatory maintenance of a normal extracellular dopamine (DA) concentration in the striatum. We used microdialysis to measure extracellular levels of DA, its precursor L-dihydroxyphenylalanine (L-DOPA), and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in mouse striatum in a model of the presymptomatic stage of Parkinsonism. This stage was induced by a single subcutaneous injection of the neurotoxin precursor 1-methyl-4-phenyl-1,2,3,4-tetrahydropyridine (MPTP) at a dose of 12 mg/kg. At 14 days after MPTP injection, the extracellular DA content substantially decreased as compared to the control; however, it did not result in alterations of motor behavior, probably due to compensatory processes directed, not to the maintenance of extracellular DA at the normal level, but rather to the elevation of neuronal sensitivity to DA. The extracellular L-DOPA content remained at the normal level. We did not find any changes in the DOPAC and HVA contents. Thus, degeneration of DA-ergic striatal axons at the presymtomatic stage of Parkinsonism is associated with a decrease in the DA content in the extracellular space. This indicates that activated compensatory mechanisms are not related to the maintenance of DA concentration in the extracellular space but rather to the increased sensitivity of target neurons to DA. [ABSTRACT FROM AUTHOR]

Current concepts hold that during learning in waking animals, new information is transmitted from the neocortex to the hippocampus, where it leaves a temporary trace in the form of a mosaic of modified synapses. During sleep, reactivation of the neuron population initially activated by the new stimulus has the result that this information is returned to the neocortex, ensuring consolidation of a permanent memory trace. Exchange of information between the neocortex and hippocampal formation is mediated mainly by the entorhinal cortex, whose internal connections, in principle, allow "messages" from the output of the hippocampal formation to return to its inputs. Our experiments in awake and sleeping rabbits demonstrated that waves of excitation can return to hippocampal field CA1 and the dentate gyrus via fibers of the perforant path, these waves having initially entered field CA1 via potentiated synapses of Schäffer collaterals; during sleep, re-entrant waves of excitation reach a maximum and have a high probability of evoking discharges of dentate gyrus neurons. Thus, the new stimulus, potentiating synaptic connections in the hippocampus and, probably, the entorhinal cortex during waking, create conditions for reactivation of the corresponding hippocampal neuron populations during sleep by waves of excitation returning via the entorhinal cortex. [ABSTRACT FROM AUTHOR]

We present results from comprehensive investigations of the separation characteristics and drag of models of cyclone-vortex separators for separating steam-water mixtures in a wide variation range of operating and design parameters. [ABSTRACT FROM AUTHOR]

A design for a miniature preamplifier for recording electrophysiological activity in freely moving small animals is proposed. The preamplifier is relatively simple to make and use and allows differential recording of neuron activity, EEG, and evoked potentials in multiple channels. When necessary the preamplifier can easily be disassembled for repair. A thin, flexible cable and a “gentle” suspension system prevent interference with the animal's free movement. The design is light in weight and allows electrophysiological activity to be recorded in mice even while they are swimming in a Morris tank. [ABSTRACT FROM AUTHOR]

A scheme of interpreting the data of two-wavelength lidar sounding is proposed. The scheme is based on functional relationships between the lidar ratios and between some integral characteristics of aerosol and the ratio of the backscattering coefficients at the sounding wavelengths. The AERONET data, results of contact aerosol measurements and multiwavelength lidar sounding, and the OPAC aerosol model are used to find these functional relationships, which are statistical in character. Analysis of data is made separately for continental, dust, oceanic, and smoke aerosols. Backscattering for mineral aerosol fractions are calculated for a model of randomly oriented spheroids. A numerical experiment shows that the errors in determining a number of integral parameters of aerosol (extinction coefficient, characteristic radius of particles, volume concentrations) that are due to the statistical straggling of lidar ratios and other specified integral characteristics are no greater than 32% if the optical thickness of the sounding layer is no greater than 1. [ABSTRACT FROM AUTHOR]

The kinetics of reduction of peroxodisulfate anions is studied on a rotating disk electrode made of gallium in sulfate solutions using the methods of linear voltammetry, chronoamperometry, and chronopotentiometry. The reduction process is shown to be complicated by the formation of an anodic film on the electrode from the products of oxidation and hydrolysis of Ga(III). Based on the results of the analysis of the data obtained, a structural model of the anodic film formed in the initial stages of Ga passivation is suggested and substantiated. It is assumed that the method of probe reactions (in our case, electroreduction of S2O8 2- anions) can be recommended for studying the metal passivation in different media. [ABSTRACT FROM AUTHOR]

The possibilities and limitations of the RRDE method in recording and identifying intermediate and target products of chromium dissolution in sulfuric acid solutions of pH 0.3–2 are analyzed on the basis of own and literature data. From the experimental data, partial currents of chromium dissolution to Cr(II) ions in the region of active dissolution of chromium and its transition into a passive state are computed. The Cr(III) ions can be discovered through the reaction of their reduction on an Hg(Au) ring electrode only at pH ≥ 1.8. The current efficiency of reactions that lead to the formation of Cr(II) and Cr(III) ions near the anodic-dissolution peak is other than 100%. Assumptions as to the causes of this effect are made. In the solutions studied, Cr(VI) ions are recorded with a 100-% current efficiency on a gold ring electrode in a transpassive region of the chromium disk potentials. [ABSTRACT FROM AUTHOR]

On the basis of a model put forward, experimental data on the electrochemical ionization of solid gallium in carbonate buffer media are analyzed. It is shown that the formation on the electrode of a matrix consisting of the hydrolysis products of gallium ions Ga(3+) is the initial anodic step. The charge transport in this matrix proceeds via an ejection mechanism. At pH > 10, this matrix transforms into a reaction layer, which supplies Ga(OH)2CO3 -complexes (at higher pH—Ga(OH)4 -anions) to the electrolyte. [ABSTRACT FROM AUTHOR]

The anodic behavior of solid gallium (99.9998%) in sulfate buffer solutions is studied by the chronopotentiometric method. The resistive passivating film that forms on the electrode surface undergoes a rather rapid destruction due to the interaction of hydroxy- and oxy-groups with the electrostatically injected hydrosulfate anions. [ABSTRACT FROM AUTHOR]

An analysis of the effect of thermal flux on the refractory products subjected to non-stationary heating or cooling, identification of the regions and the surfaces of the products liable to the maximum thermal stresses, and elimination of the thermal stresses by decreasing the linear dimensions in the section located perpendicular to the thermal flux make it possible to improve the service life of the products without changing the technological parameters during their production. [ABSTRACT FROM AUTHOR]

The transfer crystallizers of large section ensure the production of ingots of fused materials of high purity. The melting of ingots in these units is possible with arc and also with hf induction heating, and during melting there is a certain purification of the materials. The resulting fused materials can be successfully used as granular constituents in refractories for various purposes. [ABSTRACT FROM AUTHOR]

The investigations demonstrated the advantages of using electrofused periclase and aluminomagnesia spinel for the manufacture of refractory products for casting rimmed steels and of zirconia and aluminomagnesia spinel for refractories for casting killed steels. These findings were confirmed in industrial-scale tests with batching devices and refractory plates produced from these materials. [ABSTRACT FROM AUTHOR]