Influence of alkaline modification on adsorption properties of alumina

The kinetics of water vapor adsorption on alumina adsorbents at a temperature of 25 °C was studied. It was shown that modification by cations of alkali metals (K, Na) of the adsorbent based on alumina allows increasing its efficiency in the process of water vapor adsorption. The mathematical treatment of the experimental data by the dependence of water vapor adsorption on the time with the help of the Linear Driving Force (LDF) model and the dependence of adsorbent's adsorption capacity on the water vapor concentration (adsorption isotherm) by Dubinin-Astakhov equation was carried out. Constants included in the equations were defined

Effect of particle size on adsorption kinetics of water vapor on porous aluminium oxide material

Influence of the grain size of aluminium oxide material, being a product of centrifugal thermal activation of hydrargillite, on adsorption kinetics of water vapors was studied. The material was characterized by the BET method and X-ray phase analysis (XRD). Influence of gas flow rate on adsorption dynamics was studied on a laboratory installation using McBain-Bakr quartz balance. It was shown that with the fraction size greater than 0.5-1.0 mm, the rate of water vapor adsorption on this adsorbent decreased, which was connected with the influence of internal diffusion resistance. On the base of the first-order kinetic equation for the water adsorption mathematical modeling was carried out. The kinetic parameters of the equation for the various grain size samples (0.25-0.5 mm and 0.5-1.0 mm and 3.7 x 6 mm granule) were determined

Measurement of the Orbital Period of the X-ray Burster GS 1826-238 Based on Observations of Its Optical Brightness Variations

The variability of the optical and X-ray fluxes from the binary GS 1826-238 is investigated. An epoch-folding analysis of the optical data obtained with the RTT-150 telescope in 2003-2004 has revealed periodic brightness variations in the source with a period Porb = 2.24940 ± 0.00015 h with a high statistical significance. When estimating the detection significance of the periodic signal, we have specially taken into account the presence of a powerful aperiodic component ("red noise") in the source's brightness variability. The source's power density spectra in the frequency range ~10-5-0.01 Hz have been obtained. We have detected a statistically significant break in the power density spectrum of GS 1826-238 at a frequency νbr ≈ (8.48 ± 0.14) × 10-5 Hz in both optical and X-ray energy bands. We have estimated the orbital period of the binary GS 1826-238 using the correlation between the break frequency in the power density spectrum and the orbital period of binaries, Porb ∝ 1/νbr, found by Gilfanov and Arefiev (2005): Porb = 3.7 ± 0.8 h and Porb = 11.3 ± 5.9 h when using Sco X-1 and 1H 16267-273, respectively, as reference sources. It seems to us that the method for estimating the orbital periods of low-mass X-ray binaries using the correlation Porb ∝ 1/νbr may turn out to be very promising, especially for persistent low-luminosity X-ray binaries. © 2010 Pleiades Publishing, Ltd

Modeling of liquid flow in surface discontinuities

Polymer composite and metallic materials have found wide application in various industries such as aviation, rocket, car manufacturing, ship manufacturing, etc. Many design elements need permanent quality control. Ensuring high quality and reliability of products is impossible without effective nondestructive testing methods. One of these methods is penetrant testing using penetrating substances based on liquid penetration into defect cavities. In this paper, we propose a model of liquid flow to determine the rates of filling the defect cavities with various materials and, based on this, to choose optimal control modes

Shock-induced structures in copper

Shock loading of M3 copper within strain rate range of 5·10 6-5,7·10 6 s -1 reveals a nucleation of structural objects of 5-30 µm in diameter, which present the three dimensional frameworks composed from shear bands of 50-200 nm spacing. The structures are shown to be nucleated by means of interference of longitudinal and periphery release waves. Transition of the material into structure unstable state responsible for the shear banding happens when rate of change of the velocity variance at the mesoscale becomes higher than the rate of change of the mean particle velocity. The sites of nucleation of 3D-structures are speculated to be the staking faults generated under action of chaotic velocity pulsations relevant to dynamic deformation. The physical model for formation of 3D-structures takes into account the intersection of the partial dislocations and Lomer - Cottrell barriers

Theoretical optimization of the shape and size of adsorbent grains for associated petroleum gas drying

The shape of adsorbent grains used for drying hydrocarbon gas flows at a reduced hydraulic resistance of their beds are theoretically optimized. A two-velocity model of gas flow in fixed beds consisting of differently shaped holed particles is used for calculations at typical parameters of the associated petroleum gas drying process. It is shown that the optimum shape of a grain is a four-spoke ring. At an equivalent diameter of 3 mm, such a grain is 6.154 × 6.154 mm in size, and its walls and baffles are 1.026 mm thick

Role of catestatin in development and decompensation of heart failure: a literature review

The current literature review covers the role of sympathetic nervous system activation (SNS) and the significance of a new biomarker catestatin (CST), which is a chromogranin A-derived peptide, for assessing prognosis of patients with heart failure (HF). This review details the works devoted to CST metabolism and its role in clinical conditions with excessive catecholamine production, including the ability to counterbalance the adverse effects of SNS on cardiovascular system. The paper also presents the central results of studies on HF patients and shows the correlation of the CST level with HF functional class and stage. In addition, particular attention is paid on the possibilities and potential benefits of assessing the CST in addition to conventional management of patients hospitalized due to acute decompensated heart failure

Модернизация грузовых тележек: установка поперечной связи

The authors offer design of transverse connection assembly in the bogie of type 18-100 of a cargo car. The aim is to eliminate lozenging of side frames, reduce intensity of sinuous movement, vibration load and wear of parts and assemblies, improve smoothness, as well as eliminate pendular oscillations of side frames with respect to their own longitudinal axes (thus facilitating also the operation mode of bearing units and cast bearing elements). Modernization of a bogie by mounting transverse connection assembly, as well as replacing axle bearings with cassette-type bearings and adapters of MIIT design with wear-resistant vibration absorbers, assumes to substantially increase guaranteed overhaul life of freight cars.Авторами предложено конструктивное исполнение поперечной связи в тележке модели 18-100. Цель - устранить забегания боковых рам, снизить интенсивность извилистого движения, вибронагруженность и износы деталей и узлов, улучшить плавность хода, а также устранить маятниковые колебания боковых рам относительно собственных продольных осей (тем самым облегчая еще и режим работы подшипниковых узлов и литых несущих элементов). Модернизация тележки путем установки поперечной связи и адаптеров МИИТ с износостойкими вибропоглатителями предполагает существенно увеличить гарантированный межремонтный пробег грузовых вагонов