Convenient approach to making nanocomposites based on a chitosan–poly(vinyl pyrrolidone) polymer matrix and a graphene nanofiller

Conducting, mechanically durable, elastic nanocomposite films were prepared with chitosan (CS) as the polymer matrix, graphene obtained from highly exfoliated graphite as the nanofiller, and poly(vinyl pyrrolidone) (PVP) as the stabilizer of the graphene sheets. The maximum graphene content in the composites without a loss of uniformity and other useful properties increased up to 4.0 wt %. The resulting composites were characterized by scanning electron microscopy, Raman spectroscopy, X‐ray diffraction analysis, mechanical testing, and electrical conductivity testing to determine the effects of the addition of graphene on the morphology and mechanical and electrical properties of the CS–PVP–graphene nanocomposite films. In this study, we took an approach to making nanocomposites from the perspectives of green chemistry, environmental protection, regenerative medicine, and low cost. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45038.     

Hydroprocessing of straight run diesel mixed with light cycle oil from fluid catalytic cracking,using sulfide NiMo catalyst on zeolite-containing supports

It is proposed that the sulfide NiMo system supported on alumina-SAPO-31 composite (NiMo/Al₂O₃-SAP catalyst) be used to obtain high-quality diesel fuel from a mixture of straight run diesel (SRGO) and light cycle oil (LCO) produced by fluid catalytic cracking (FCC). It is shown that the use of this catalyst ensures the synthesis of diesel fuel of higher quality upon hydroprocessing a feedstock with 30 wt % LCO, compared to the traditional sulfide NiMo/Al₂O₃ or CoMo/Al₂O₃ catalysts. It is found that the content of aliphatic hydrocarbons is raised in the products of hydrotreatment, compared to the initial feedstock. This confirms the ability of NiMo/Al₂O₃-SAP catalyst to facilitate the reaction of ring opening. Using the proposed catalyst should improve the quality of diesel fuels obtained via the hydroprocessing of LCO-containing feedstock.     

Numerical study of the effect of burnout on the ignition characteristics of polymer under local heating

This paper presents the results of a numerical study of the effect of burnout on the ignition delay of a typical thermoplastic polymer (polymethylmethacrylate) by a metal particle heated to a high temperature. The initial temperature of the energy source was varied from 960–1150 K. Three ignition modes of the polymer can be distinguished according to the temperature of the heat source, ignition delay, and the position of the ignition zone in the vicinity of the hot particle. It is found that under local heating conditions, the burnout of the heated region of the near-surface layer of the polymer has an insignificant effect (less than 5%) the increase in the basic characteristic of the process—the ignition delay. At the time of initiation of combustion, the degree of thermal decomposition of the polymer (degree of conversion) does not reach even 15% in the section corresponding to the maximum heat flux from the heat source. It is shown that the ignition delay increases more significantly when accounting for the temperature dependence of the thermal properties of polymethylmethacrylate than when accounting for the burnout factor. The induction period is increased by 15–25% due to an increase in the accumulating capacity of the polymer and heat transfer rate from the heated region of the near-surface layer into the depth of the material.     

Cryopetrophyte communities of the West Sayan Ridge

Abstract

The paper presents research in eco-coenotic features of cryopetrophyte communities of the Osevoi Ridge in the Western Sayan Mts. All communities studied are in the association Saxifrago oppositifoliae–Rhodioletum quadrifidae. This association includes all communities with a predominance of alpine and arctalpine petrophytes, which are largely facultative and obligate calciphile plants. The coenoflora of the association Saxifrago oppositifoliae–Rhodioletum quadrifidae is represented by 54 species of higher vascular plants. The dominant species in its structure are those of Holarctic distribution and species generally confined to the Altai-Sayan mountain region, with Papaver pseudocanescens, Poa smirnowii, Sajanella monstrosa, Saussurea foliosa and Saxifraga melaleuca being endemics. In the structure of the belt-zonal groups, arctalpine and alpine species dominate. Among ecological groups, obligate and facultative petrophytes, generally cryophytes, are dominant. The predominance of some particular belt-zonal and ecological groups of species indicates greater specificity of the environmental conditions in which the communities were formed and are currently being formed.     

Particle flow, mixing, and chemical reaction in circulating fluidized bed absorbers

A mixing model has been developed to simulate the particle residence time distribution (RTD) in a circulating fluidized bed absorber (CFBA). Also, a gas/solid reaction model for sulfur dioxide (SO₂) removal by lime has been developed. For the reaction model that considers RTD distribution inside the core and annulus regions of a CFBA, a macrochemical reaction can be simulated based on microchemical reaction dynamics. The presented model can predict SO₂ and lime concentration distributions inside the CFBA, and give the amount of lime needed to remove a given percentage of SO₂. It is found that SO₂ concentration decreases with the increase of CFBA distance from the bottom in the core region. However, lime concentration exhibits a very slight variation in the core region. This means that lime is efficiently utilized to remove SO₂. The model also predicts that SO₂ partial pressure at the exit of the CFBA decreases with the increase in the percentage of fresh lime injected in the CFBA.     

Numerical analysis of burnup of coke particles in dry air

A mathematical model, an algorithm, and a program have been proposed for the calculation of the burnup of individual coke particles in dry air. A numerical analysis is made of the effect of the model parameters on the burnup and thermal destruction of the particles.Institute of Problems of Energy Supplies, Academy of Sciences of Ukraine, Kiev 252070. Translated from Fizika Goreniya i Vzyrva, Vol. 30, No. 2, pp. 33–42, March–April, 1994.     

The nature of the synergistic effect of binary tetralin-alcohol solvents in Kansk-Achinsk brown coal liquefaction

Kansk-Achinsk brown coal hydrogenation and swelling in tetralin, in low molecular alcohols, in other solvents and in binary mixtures were studied. Tetralin was found to be the most effective liquefaction solvent, but methanol and ethanol were the active ones in coal swelling. Synergistic effects were observed when the mixtures of tetralin and methanol or ethanol were used for liquefaction and swelling. The effect of binary solvents was shown to be due to the ability of alcohol components to cause brown coal to swell improving the availability of the fragments of coal matter for the reactive hydrogen donor tetralin molecules.     

Masses based on Arkalyk clay for guniting steel-teeming ladles

Conclusions The authors investigate the properties of gunite masses based on Arkalyk clays with regard to service conditions in steel-teeming ladles used in open-hearth manufacture of steel. The optimal composition of the mass is as follows: 90% chamotte, 10% clay, and 10% binder (above 100%). Industrial tests have been performed on a mass for guniting 230-ton steel-teeming ladles of the MMC. The durability of a gunite layer 30–35 mm thick is about 6 pourings. The results confirm that Arkalyk clay is a promising material for making gunite masses.Translated from Ogneupory, No. 6, pp. 30–35, June, 1981.