A technique for determining the microstructural wettability of a carbonate rock using a scanning electron microscope (SEM) in the low-vacuum mode employing a special chamber and the results of ...respective experiments are described. To this end, the principle of the spontaneous formation of microscopic water droplets on the sample surface as a result of vapor condensation and measurement of the contact angle on SEM images is implemented. The possibility of determining the surface properties of dispersed particles with different mineral compositions is shown. Analysis of the surface properties of the pore space of oil-saturated rocks using a SEM makes it possible to specify the wetting properties in the pore space at the microscale level. These studies are of practical importance for petroleum geology. Detailed determination of the wettability makes it possible to predict the water cut of the produced products and provides additional possibilities for adopting special methods to decrease the amount of residual oil in the reservoir and increase the production of hydrocarbons.
Abstract
The major task of detecting axions or axion-like particles has two challenges. On the one hand, the ultimate sensitivity is required, down to the energy of a single microwave photon of the ...yoctojoule range. On the other hand, since the detected events are supposed to be rare, the dark count rate of the detector must be extremely low. We show that this trade-off can be approached due to the peculiar switching dynamics of an underdamped Josephson junction in the phase diffusion regime. The detection of a few photons’ energy at 10 GHz with dark count time above 10 s and the efficiency close to unity was demonstrated. Further enhancements require a detailed investigation of the junction switching dynamics.
Display omitted
•T-15MD project is the initial technical base for creating fusion neutron source for atomic energy needs.•The preassembly of the tokamak T-15MD magnet system together with the vacuum ...vessel was completed.•Most of tokamak systems were manufactured and preliminary tested before the final assembly of tokamak.•All the diagnostic equipment is available and part of it was used in experiments on tokamak T-10.•Physical start-up T-15MD is scheduled for December 2020 year.
At the present time, in the NRC Kurchatov Institute under the auspices of the Federal Target Program “Nuclear energy-technologies of new generation for period 2010–2015 and to the prospect until 2020” the tokamak T-15MD and supporting facilities are being built. The preassembly of the tokamak T-15MD magnet system together with the vacuum vessel was completed at a plant in Bryansk. All elements of the magnet system and vacuum vessel have been delivered to the NRC “Kurchatov Institute” in Moscow for the tokamak T-15MD assembly. It is expected that the T-15MD assembly will be completed in March of 2019. The reconstruction of the sub-station 110/10/04 kV for own needs was completed in 2017 and the reconstruction of the main sub-station 110/10/1 kV, 300 MW was completed in 2018. Twenty- two of the new transformers 10/1 kV and 20 new thyristor convertors will be installed during 2018–2019 period. One gyrotron with output power 1 MW for pre-ionization should be installed in 2019. Tokamak T-15MD connection to water and electrical communication and also the adjustment of control system will be completed in the middle of 2020. Physical start-up T-15MD is scheduled for December 2020 year.
Abstract
Bolometers for balloon and space missions have seen extensive development because of their capacity to test primordial conditions of the Universe. The major improvements consist in lowering ...the operating temperature to reach higher sensitivities. Here we show that an array of 192 cold-electron bolometers (CEB) demonstrates photon-noise-limited operation at the cryostat temperature of 310 mK due to effective self-cooling of the absorber. The direct electron cooling of nanoabsorber placed between normal metal - insulator - superconductor junctions has considerably higher efficiency than indirect cooling through massive suspended platform, that requires overcoming a weak electron-phonon conductance. The electron temperature reached 120 mK without a power load, and 225 mK with a 60 pW power load with self-noise of a single bolometer below
$$3\cdot 1{0}^{-18}\ {\rm{W}}\ {{\rm{Hz}}}^{-1/2}$$
3
⋅
1
0
−
18
W
Hz
−
1
∕
2
at a 0.01 pW power load. This bolometer works at electron temperature less than phonon temperature, thus being a good candidate for future space missions without the use of dilution refrigerators.
—
An approach and an algorithm to find the orientation of the pore space of oil and gas reservoir rocks are proposed based on contrast cathodoluminescence images of the surface of polished sections ...of the rocks obtained using a scanning electron microscope. The microstructural orientation of the pores is found from electron microscopic images of various rocks with a complex pore-space structure and anisotropy of the filtration properties for rocks of various lithological types. This algorithm makes it possible to solve problems related to the anisotropy of filtration properties in petrophysical studies of rocks. The proposed method of finding the orientation is of great practical importance, because the oriented pore space affects the ways of developing hydrocarbon deposits. Determination of the direction of orientation of the pore space allows one to take into account the deviation of fluid flow during its injection into the well and to improve the coverage of oil-saturated reservoirs.
—
The time and energy resolutions were measured for four prototypes of the PHOS electromagnetic calorimeter for the ALICE experiment at the Large Hadron Collider at CERN. Each prototype was made up ...of nine identical detection elements assembled as a 3 × 3 array. The detection element was based on a lead tungstate (PbWO
4
) scintillating crystal with a length of 180 mm and a cross section of 22 × 22 mm
2
, which was viewed from its end face by a photodetector. Avalanche photodiodes and silicon photomultipliers with different active areas (Hamamatsu, Japan) were used as photodetectors. The measurements were made with the electron component of secondary particle beams of the PS proton synchrotron at CERN in the momentum range of 1−10 GeV/
c
at a temperature of 17.5°C.
Display omitted
•Laser ablation in liquid phase was used to prepare both Bi and Si based single colloids.•When mixed together, the colloids remain mainly unreacted in absence of additional ...irradiation.•Upon irradiation with laser, the mixed colloid gives rise to a new nanomaterial containing bismuth silicate phases.•The novel nanomaterial proves to be efficient photocatalyst for degrading rhodamine B and phenol.
Having a wide range of applications, bismuth silicate-based materials (BSO) attract attention of numerous researchers. Typically, they are synthesized either from active chemicals or through high-energy impact on their precursors. The present work is the first report on BSO-based nanomaterials prepared via laser processing in liquid phase in which the following two-step scheme was realized: (1) Individual colloids of Bi- and Si-based nanoparticles were obtained via ablating their metallic targets in distilled water and then mixed; (2) Post-treatment of the mixed colloid was performed with the same laser beam as in stage (1). The products obtained after drying of non-treated and post-treated mixed colloids (denoted as samples BSO and BSO_hν, respectively) were carefully characterized using a set of microscopic, spectroscopic and electrochemical analyses, after which their photocatalytic performance in presence of model organic dye (rhodamine B) and phenol was tested. The additional laser treatment was found to lead to active interaction between Bi- and Si-containing species and stimulated formation of phases with Bi-O-Si bonds. The post-irradiated sample BSO_hν showed improved stability and catalytic performance, thus opening avenues for wider use of laser processing in liquids as a method allowing for preparation of nanostructures with complex chemical composition.
The procedure and results of microstructural studies using a scanning electron microscope of samples of carbonate rocks of a full-scale filtration model of one of the layers of an oil-and-gas ...condensate field are shown. A comparative analysis of the parameters of the pore space in the samples is given and the efficiency of the test core model is shown in terms of minimizing filtration “jumps” at the contacts of the samples.
Single-walled carbon nanotubes doped with silicon and nitrogen atoms, SiС
138
N
4
and SiC
137
N
6
, were studied at the DFT ωB97XD/DGDZVP level. Analysis of the atomic charges allowed determination ...of the most probable sites of oxygen adsorption, namely, the silicon atom in the N
x
(
x
= 3 and 4) environment and the C=C bond near the SiN
x
fragment. The free energy profiles of the oxygen electroreduction reaction in acidic and alkaline media on the active sites of model catalysts were obtained. It was found that the silicon-, nitrogen-doped carbon nanotubes with the silicon atom in the center of a planar SiN
4
fragment can show superior catalytic properties due to the activation of the carbon atoms adjacent to this fragment.
PDF
