The sensitivity of gravitational-wave detectors is limited by the mechanical loss associated with the amorphous coatings of the detectors' mirrors. Amorphous silicon has higher refraction index and ...lower mechanical loss than current high-index coatings, but its optical absorption at the wavelength used for the detectors is at present large. The addition of hydrogen to the amorphous silicon network reduces both optical absorption and mechanical loss for films prepared under a range of conditions at all measured wavelengths and temperatures, with a particularly large effect on films grown at room temperature. The uptake of hydrogen is greatest in the films grown at room temperature, but still below 1.5 at.% H, which show an ultralow optical absorption (below 10 ppm) measured at 2000 nm for 500-nm-thick films. These results show that hydrogenation is a promising strategy to reduce both optical absorption and mechanical loss in amorphous silicon, and may enable fabrication of mirror coatings for gravitational-wave detectors with improved sensitivity.
This paper considers the synthesis of a novel nanocomposite based on reduced graphene oxide and oxidized carbon nanotubes modified with polyaniline and phenol-formaldehyde resin and developed through ...the carbonization of a pristine aerogel. It was tested as an efficient adsorbent to purify aquatic media from toxic Pb(II). Diagnostic assessment of the samples was carried out through X-ray diffractometry, Raman spectroscopy, thermogravimetry, scanning and transmission electron microscopy, and infrared spectroscopy. The carbonized aerogel was found to preserve the carbon framework structure. The sample porosity was estimated through nitrogen adsorption at 77 K. It was found that the carbonized aerogel predominantly represented a mesoporous material having a specific surface area of 315 m
/g. After carbonization, an increase in smaller micropores occurred. According to the electron images, the highly porous structure of the carbonized composite was preserved. The adsorption capacity of the carbonized material was studied for liquid-phase Pb(II) extraction in static mode. The experiment results showed that the maximum Pb(II) adsorption capacity of the carbonized aerogel was 185 mg/g (at pH 6.0). The results of the desorption studies showed a very low desorption rate (0.3%) at pH 6.5 and a rate of about 40% in a strongly acidic medium.
A novel sorption nanocomposite material is synthesized. A method for manufacturing of a nanocomposite based on graphene oxide (GO) modified with a natural sulfo derivative of lignin (lignosulfonate ...(LS)) followed by lyophilization is developed. The modification is aimed at an increase in the sorption capacity of the final material and a decrease in the content of expensive GO. Several variants of the nanocomposite with different contents of the original components are synthesized. The properties of the resulting nanocomposite are studied with the aid of transmission electron microscopy, Raman and IR spectroscopy, X-ray diffraction, and thermogravimetry. The parameters of the porous space were determined using nitrogen adsorption. The sorption capacity of the nanocomposite is assessed using sorption study with extraction of two types of pollutants from aqueous solutions: organic (synthetic dye methylene blue (MB)) and inorganic (lead ions). The adsorption is performed under static conditions in a limited volume. The experimental results show that a GO/LS ratio of 2:1 provides the best sorption capacity with respect to lead ions (179 mg/g) and MB molecules (1822.3 mg/g) at a contact time of 20 min. Thus, the experimental study proves the expediency of manufacturing of the GO/LS nanocomposite as a sorption material for removing of organic and inorganic contaminants.
Purpose of reseach. The paper considers the process of selective pre-destruction of interphase boundaries in iron ores by using magnetic-pulse treatment. When analyzing the stress-strain state and ...viscous fracture, the relative similarity of the fracture criteria in the main minerals of iron ores due to magnetically-striction deformation of magnetite grains. Methods .It has been established that the strength and toughness of the destruction of magnetite exceeds the analogous properties of calcite in the composition of skarn iron ores, the strength and toughness of quartz fracture exceeds the analogous properties of magnetite. A difference in the character of the destruction of skarn ores and ferruginous quartzites. The criterion for estimating the degree of softening of interphase boundaries in iron ores due to the magnetic-impulse action based on the probabilistic approach is formulated. Results .A theoretical estimate is made of the degree of selective softening of iron ores under magnetic-pulse treatment, taking into account the strength and magnetostriction properties of magnetite. The results of experiments on nanoindentation of interphase boundaries before and after magnetic-pulse processing are presented. Conclusion . By analyzing the lengths of developing microcracks under the influence of a nanoindenter, the possibility of reducing the fracture toughness after a magnetic pulse treatment of iron ore.
Synopsis We report on the resonant coherent excitation (RCE) of the 2s-2p3 2 transition in Li-like U89+ with an enhanced energy resolution, which was achieved by reducing the projectiles momentum ...spread. The kinetic temperature of the beam was decreased by electron cooling in the ESR, and the collisional momentum broadening in the target was suppressed by the use of thin crystal (1.0 and 2.5 μm-thick). The resonance width was observed to be ∼1.4 eV in FWHM, which is three-times narrower than that from the previous work.
This article is devoted to the preparation of track-etched membranes based on polyvinylidene fluoride irradiated with krypton ions for membrane distillation. The track-ethed membranes performance ...relationship to the of the membrane distillation conditions such as the concentration of salts in the feed solution, temperature and charge of the dissolved salt cation) was studied. Also the sensitizing effect of dimethylformamide on the membrane pores diameter and UV-radiation on the formation of the track-etched membrane with a given pore size were studied.
Relevance. The relevance of the topic comes from its various aspects and manifestations of behavior aimed at helping other people and society, including using the digital environment. The article ...discusses the technology of students’ project activities for the creation of prosocial media. The experience of prosocial design on the platform of the University 20.35 is presented.
The purpose of the study. Based on the study of the attitude of young people to media resources promoting assistance to other people and society, to develop and implement educational intensive technology to create by students prosocial media.
Methods and methodology. The methodological basis of the study was the approaches of media education. Methods: data selection and systematization, document analysis, Internet media monitoring, quantitative analysis of publications in youth Internet media, design. Empirical data are comprehended and processed using content analysis, quantitative analysis methods (descriptive statistics, percentage analysis. The calculations were made on the basis of the SPPS 22 statistical software package.
Results. The preferences of young people in the choice of forms of presentation of prosocial topics in the media space are revealed, their reactions to prosocial posts, blogs, videos, publications are studied, the structure of the projected prosocial media environment is determined. An educational intensive technology has been implemented to create a test prototype for the prosocial media “Let’s make the world a better place!”.
Conclusion. Based on the results of the study of the attitude of young people to prosocial media, a technology for teaching the design of prosocial media was developed and implemented, which allowed students to form attitudes to prosocial activity.
The scope of the results. The results of the study should be taken into account when developing programs and projects aimed at ensuring the digital socialization of young people.
PDF
