Composition of the water-soluble humic preparations of mechanically activated brown coals

Conditions for the solid-phase mechanochemical activation of coals, which make it possible to substantially increase the yield of water-soluble humic preparations enriched in humic acids and mineral elements, are given in this work. It was found that the humic preparations isolated from mechanically activated coals are characterized by an increase in the antioxidant activity and a change in the cationic and anionic composition. The concentration of acidic ionogenic groups in humic acids increased.     

Solar/visible light photocatalytic dye degradation using BaTi1−xFexO3 ceramics

BaTi_1−xFe_xO₃ compositions (for x = 0, 0.1, and 0.2) were prepared via a solid-state reaction route. The presence of iron (Fe) in barium titanate (BaTiO₃) eventually decreased the energy bandgap; thus, its utilization for water cleaning application through photocatalysis process was explored (using methylene blue [MB] dye as an indicative pollutant in water). Characterization of the synthesized powder was performed through scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. The bandgap of the synthesized powder was calculated as 3.2, 2.12, and 1.67 eV for BaTi_1−xFe_xO₃ compositions (for x = 0, 0.1, and 0.2), respectively. BaTi_0.8Fe_0.2O₃ powder showed excellent results, and ∼71% of the MB dye (∼5 mg/L concentrated) was degraded using the photocatalysis process under visible light. To check the potentiality of BaTi_1−xFe_xO₃ compositions (for x = 0, 0.1, and 0.2), the photocatalysis process was carried out by changing the concentration of MB dye (2.5–10 mg/L with a step of 2.5 mg/L) and the amount of BaTi_0.8Fe_0.2O₃ powder (0.05–0.2 g with a step of 0.05 g) for ∼5-mg/L concentrated MB dye. The treated water was further used as a growth parameter and phytotoxicity analysis through germination index on the wheat seeds. Lastly, the BaTi_1−xFe_xO₃ compositions (for x = 0, 0.1, and 0.2) were explored for water cleaning applications under real-time solar irradiation.     

Effect of phyllanthus emblica biodiesel based lubricant on cylinder liner and piston ring

In the present time, need of biogenic lubricants is the focusing area which will be biodegradable, avirulent and eco-friendly. Current experimental tests depict the effect of ‘Phyllanthus emblica’ a non-edible feedstock through pin on disc tribo tester. Tests were conducted to evaluate the impact of 0, 10, 20 and 30 % blending of Phyllanthus emblica with SAE20W40 lubricating oil on cylinder liner and piston ring. Promising results have been manifested with 10 % blending of biodiesel (BD) with lubricating oil in terms of coefficient of friction and specific wear rate in comparison with other examined feedstock. For analysis of wear debris in the used oil analytical ferrography was also done. The effects of temperature on wear and friction characteristics have also been discussed.

     

Compensation of reflection from an RF absorbent material with the help of a lattice of double split rings

The frequency dependences of the coefficients of reflection from a lattice of double split rings excited by an RF magnetic field and from an RF-absorbent composite based on resistive films or fibers are analyzed. It is shown that partial reflections from the surface of the composite and the closely spaced lattice can compensate each other and, thus, the reflection from the composite can be significantly reduced. It is experimentally confirmed that the reflection can be decreased by more than 15 dB as compared to the reflection from the composite in the absence of the lattice.     

Controlled bandpass frequency-selective surfaces

Bandpass frequency-selective surfaces (FSSs) controlled by varactors and representing biperiodic lattices formed from slotted squares in a thin metallic screen are considered. Main factors affecting the FSS tuning range with different circuits for connection of control varactors are experimentally evaluated. Experimental results obtained by the waveguide method of measuring the transmission coefficient through samples of both individual FSS elements loaded with varactors of various types and lattices consisting of these elements at microwave frequencies are presented. Based on the measured data, attainable values of the relative tuning of the FSS resonance frequency are evaluated: f _max/f _min = 1.4 for control circuits with two MA46N120 low-capacitance varactors in each FSS element and f _max/f _min = 1.5 for control circuits with one VV857 medium-capacitance varactor.     

Russian and foreign millimeter band radio measuring instruments

The present state of the development and production of Russian and foreign radio-measuring instruments in the frequency range up to 178.4 GHz (and higher) and the proposed glossary of the new generation of Russian instruments are considered.     

Production of isobutylene from acetone over micro–mesoporous catalysts

The production of isobutylene from acetone over micro–mesoporous catalysts with different mesopore contents, which have been prepared using hydrothermal recrystallization of mordenite (MOR) zeolite modified with cesium acetate by incipient wetness impregnation, has been studied. It has been shown that cesium is inserted into the cation positions during the modification, at the same time the number of Brønsted acid sites in the samples decreased. It has been found that an increase in the content of mesopores in the catalyst leads to an increase in the initial rates of acetone conversion and isobutylene formation as a result of removing diffusion limitations. Brønsted acid sites have been shown to be preferable for the selective production of isobutylene from acetone. Micro–mesoporous materials operate more stably as compared to microporous materials.     

Investigations on the thermal effects in non-circular journal bearings

A comparative study based on the thermal performance of elliptical and offset-halves journal bearings has been carried out by solving energy equation while assuming Parabolic Temperature Profile Approximation across the fluid film for faster computation of temperatures. Investigation for the rise in oil film temperatures, thermal pressures, load capacity, and power loss for three commercially available grade oils have been carried out for bearing configurations under study. It has been found that the offset-halves journal bearing runs cooler when compared with elliptical journal bearing profile with minimum power loss and good load capacity using Oil 2 as lubricant for which minimum thermal degradation has been observed.     

Temporal characteristics of light collection in the liquid scintillation counter with a volume of 1.5 m<Superscript>3</Superscript> and quasi-mirror reflection

The temporal behavior of light collection in the 1.5-m³-volume mirror-reflecting counter filled with a highly transmitting liquid scintillator has been investigated. Using the Monte Carlo method and assuming that the luminescence decay time of the liquid scintillator is zero (τ_LS = 0), it has been ascertained that, in the case of a short flash in a counter, the exponential phase of light collection is characterized by time τ_col = 15.0 ± 1.7 ns, which is does not depend on scattering of light in the medium. The measured exponent index τ_act = 37 ± 3 ns of an actual pulse due to a muon is determined both by light collection time τ_col ≈ 15 ns and luminescence decay time τ_LS ≈ 20 ns of the scintillator in the large-volume counter.