A composite aerogel with superhydrophobic external surface has been synthesized from reduced graphene oxide and polytetrafluoroethylene taken in a weight ratio of 1 : 1. The porous structure of the ...aerogel has been studied by the standard contact porosimetry method (SCPM). The porosimetric curves measured with respect to octane and water intersect in the region of small pores, thereby leading to the fact that the specific surface area of the aerogel in water is much larger than that in octane, although octane is known to wet any material almost ideally. This phenomenon, which is referred to as “superhydrophilicity,” is explained by the fact that, in the region of mesopores, a sample swells in water due to the hydration of surface –CO and –COH groups, which have been identified with the help of IR and Raman spectroscopies. Thus, the outside surface of the aerogel granules is superhydrophobic, while their interior is superhydrophilic in the region of small pores. As follows from the SCPM data, the total porosity and specific surface area of the aerogel are substantially larger than those of Vulcan XC-72 carbon black, which is a standard carrier for Pt catalysts used in fuel cells based on proton-exchange membranes. Oxygen electroreduction at the aerogel, containing Pt deposited in an amount of 28 µg/cm
2
, has been studied by the method of rotating disk electrode (RDE) in an aqueous 0.5 M H
2
SO
4
solution, and the results obtained have been compared with the data on standard commercial Pt (20%)/Vulcan XC-72 catalyst. It has been shown that the limiting diffusion RDE currents for Pt supported on the hydrophobic–hydrophilic aerogel are markedly higher than those for the standard catalyst because of the easier access of oxygen to the reaction zone as compared with hydrophilic Vulcan XC-72 carbon black carrier.
Methods for the formation of liquid, microdroplet, cluster, and gas targets in vacuum for use in laser-plasma radiation sources are considered. The characteristics of the used target-formation ...systems and gas-supply systems based on them are given. These systems form pulsed and static jets with low mass flow, on the order of ~70 mL/h of liquid or 1500 cm
3
/h of gas, which allows pumping out the vacuum volume with one turbomolecular pump with a capacity of 1000 L/s.
Fermi-LAT has made a significant contribution to the study of high-energy gamma-ray diffuse emission and the observation of ∼3000 discrete sources. However, one third of all gamma-ray sources (both ...galactic and extragalactic) are unidentified, the data on the diffuse gamma-ray emission should be clarified, and signatures of dark matter particles in the high-energy gamma-ray range are not observed up to now. GAMMA-400, currently developing gamma-ray telescope, will have the angular (∼0.01° at 100 GeV) and energy (∼1% at 100 GeV) resolutions in the energy range of 10-1000 GeV better than the Fermi-LAT (as well as ground gamma-ray telescopes) by a factor of 5-10 and observe some regions of the Universe (such as Galactic Center, Fermi Bubbles, Crab, Cygnus, etc.) in the highly elliptic orbit (without shading the telescope by the Earth) continuously for a long time. It will permit to identify many discrete sources, to clarify the structure of extended sources, to specify the data on the diffuse emission, and to resolve gamma rays from dark matter particles.
The study of the organic matter of Riphean-Vendian deposits, the features of its distribution are the subject of research by many authors. The problem of hydrocarbon of these deposits remains ...relevant. We have conducted studies of deep-seated rocks of the Lower Riphean of the kaltasinskaya suite of the Eastern-Askinskaya area, with an increased content of organic matter in individual intervals. In addition to standard research methods, the method of nuclear magnetic relaxation in a low magnetic field was used. This method allows determining the phase state of organic matter in the original rock without any impact and after isothermal heating of the rock at 350°C. The free induction signal and the type of solid-phase signal, which corresponds to the waveform for the asphaltene component of the oil, were analyzed. The predominant part of the liquid-phase signal - about 35%, is characterized by a transverse relaxation time of 540 ¼s, corresponding to the resinous component of organic matter. The quantitative ratio of asphaltenes before and after heat treatment was also analyzed. A significant decrease in its amount was recorded. During thermal exposure, more than 55% of light, more mobile hydrocarbon molecules are formed in the liquid-phase part of organic matter.
In Russia several space missions are now planned to study transient luminous events in the atmosphere and high‐energy charged particles at satellite altitudes. The experimental goal is to investigate ...the origin of the high‐energy electrons and gamma ray quanta for specific transient luminous events (TLEs) and their role in the ionosphere‐magnetosphere system. Simultaneous measurements of electrons at the orbit of the satellite and TLE atmospheric radiation in many wavelength bands will be performed in two missions, Tatiana‐2 and RELEC. In the TUS mission UV transient event detection will be accompanied by measurements of the weak UV emission from the “seed” electrons of extensive air showers of extremely high‐primary energies.
The program of physical studies on the
Vernov
satellite launched on July 8, 2014 into a polar (640 × 830 km) solar-synchronous orbit with an inclination of 98.4° is presented. We described the ...complex of scientific equipment on this satellite in detail, including multidirectional gamma-ray detectors, electron spectrometers, red and ultra-violet detectors, and wave probes. The experiment on the
Vernov
satellite is mainly aimed at a comprehensive study of the processes of generation of transient phenomena in the optical and gamma-ray ranges in the Earth’s atmosphere (such as high-altitude breakdown on runaway relativistic electrons), the study of the action on the atmosphere of electrons precipitated from the radiation belts, and low- and high-frequency electromagnetic waves of both space and atmospheric origin.
The possible effects of technogenic impacts on the ionosphere, with the continuing trend towards its sustainable growth, are unknown today. It is therefore very important and urgent task to conduct ...statistically valid research related to the study of variations of ionospheric parameters due to the influence of powerful technogenic factors, primarily due to a significant increase of the electromagnetic energy production. In this paper, we discuss new results of observations of electromagnetic fields in the ionosphere at the power lines main frequency of 50 (60) Hz and its harmonics onboard SICH-1M (2004) and CHIBIS-M (2012–2014) satellites. The spatial distribution of the observed phenomena and their connection with possible ground-based sources–powerful transmission lines is presented. It is concluded that organization of regular monitoring of technogenic fields may allow continuous control of energy consumption in both the local (within a country or even a powerful consumer) and global scales.
The GAMMA-400 gamma-ray telescope is designed to measure the gamma-ray fluxes in the energy range from ∼20 MeV to ∼1 TeV, performing a sensitive search for high-energy gamma-ray emission when ...annihilating or decaying dark matter particles. Such measurements will be also associated with the following scientific goals: searching for new and studying known Galactic and extragalactic discrete high-energy gamma-ray sources (supernova remnants, pulsars, accreting objects, microquasars, active galactic nuclei, blazars, quasars). It will be possible to study their structure with high angular resolution and measuring their energy spectra and luminosity with high-energy resolution; identify discrete gamma-ray sources with known sources in other energy ranges. The major advantage of the GAMMA-400 instrument is excellent angular and energy resolutions for gamma rays above 10 GeV. The gamma-ray telescope angular and energy resolutions for the main aperture at 100-GeV gamma rays are ∼0.01% and ∼1%, respectively. The motivation of presented results is to improve physical characteristics of the GAMMA-400 gamma-ray telescope in the energy range of ∼20-100 MeV, most unexplored range today. Such observations are crucial today for a number of high-priority problems faced by modern astrophysics and fundamental physics, including the origin of chemical elements and cosmic rays, the nature of dark matter, and the applicability range of the fundamental laws of physics. To improve the reconstruction accuracy of incident angle for low-energy gamma rays the special analysis of topology of pair-conversion events in thin layers of converter performed. Choosing the pair-conversion events with more precise vertical localization allows us to obtain significantly better angular resolution in comparison with previous and current space and ground-based experiments. For 50-MeV gamma rays the GAMMA-400 gamma-ray telescope angular resolution is better than 50.
We present the first experimental results on the observation of optical transients, gamma-ray bursts, relativistic electrons, and electromagnetic waves obtained during the experiment with the RELEC ...complex of scientific equipment on the
Vernov
satellite.
The main goal of the Vernov mission is the study of magnetospheric relativistic electron precipitation and its possible influence on the upper atmosphere as well as the observation of Transient ...Luminous Events (TLE) and Terrestrial Gamma Flashes (TGF) across a broad range of the electromagnetic spectrum.
The RELEC (Relativistic Electrons) instrument complex onboard the Vernov spacecraft includes two identical X- and gamma-ray detectors of high temporal resolution and sensitivity (DRGE-1 and DRGE-2), three axis position detectors for high-energy electrons and protons (DRGE-3), a UV TLE imager (MTEL), a UV detector (DUV), a low frequency analyser (LFA), a radio frequency analyser (RFA), and AN electronics module responsible for control and data collection (BE).
The RELEC mission conducts the following experiments:
–simultaneous observations of high-energy electron and proton fluxes (within the energy range of ∼0.1–10.0MeV) and low-frequency (∼0.1–10kHz) electromagnetic wave field intensity variations with high temporal resolution (∼1ms);–fine time structure (∼1μs) measurements of transient atmospheric events in UV, X- and gamma rays with an optical imaging capability with a resolution of ∼1km in wide field of view (FOV);–measurements of electron flux pitch-angle distributions in dynamical ranges from ∼0.1 up to 105 part/cm2/s;–monitoring of charged and neutral background particles in different areas of near-Earth space.
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