Time filter

Source Type

Aristov Y.I.,RAS Boreskov Institute of Catalysis
Applied Thermal Engineering | Year: 2013

Improvement of the dynamics of adsorptive chillers (ACs) is the main target for making them more competitive with absorption and compression machines. This paper addresses recent advances in understanding and optimizing the AC dynamics. This analysis is generally based on the dynamic experiments performed in a small "adsorbent-heat exchanger" (Ad-HEx) unit which closely imitates the conditions of isobaric stages of AC. All results concern configuration of Ad-HEx unit with n layers of loose adsorbent grains (n = 1, 2 and 4). The main experimental findings are discussed and practical recommendations on improving the AC dynamics are made. The Fickian diffusion model of coupled heat and mass transfer at isobaric stages of AC cycle is used to describe the experimental data and study the evolution of water concentration in vapour and adsorbed phases inside the grain as well as the effect of the adsorption isobar shape. These experimental and numerical studies have revealed that the AC dynamics can be significantly improved by a proper management of Ad-HEx design, durations of the isobaric phases of AC cycle, and the shape of adsorption isobar. © 2013 Elsevier Ltd. All rights reserved.

Kholdeeva O.A.,RAS Boreskov Institute of Catalysis
European Journal of Inorganic Chemistry | Year: 2013

This short review paper summarizes recent findings in the field of H 2O2 activation over TiIV centers on the basis of model studies of Ti-containing polyoxometalates (Ti-POM) that used both experimental and computational techniques. Alkene epoxidation with H 2O2 mediated by two different POMs, the Ti-monosubstituted Keggin-type POM, [PTi(OH)W11O39]4- (1), and the Ti-disubstituted sandwich-type POM, [Ti2(OH)2As 2W19O67(H2O)]8- (2), which contain well-defined six- and five-coordinate titanium atoms, respectively, as well as some other Ti-POMs, has been explored to elucidate the role of the TiIV coordination environment in this reaction. The effect of the Ti-POM protonation state on the mechanism of H2O 2 activation has been analyzed in the context of its relevance to alkene epoxidation. The crucial factors that favor the heterolytic oxidation mechanism that leads to the selective formation of epoxides have been disclosed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aristov Y.I.,RAS Boreskov Institute of Catalysis
Applied Thermal Engineering | Year: 2013

Booming progress in the materials science offers a huge choice of novel porous solids which may be used for adsorption transformation of low temperature heat. This communication gives an overview of original and literature data on several classes of materials potentially promising for this important application, namely, metalaluminophosphates (AlPOs, SAPOs, MeAPOs), metal-organic frameworks (MIL, ISE, etc.), ordered porous solids (MCM, SBA, etc.), porous carbons and various composites (SWSs, AlPO-Al foil). For the SWS composites, we briefly considered the recent trends in their developing, namely, usage of host matrices with uniform pore dimensions and binary salt systems. We hope that this review will give new impulses to target-oriented research on the novel adsorbents for AHT and may also be beneficial for further consolidating international activities in materials science and heat transformation applications. © 2012 Published by Elsevier Ltd.

Lysova A.A.,RAS Boreskov Institute of Catalysis | Koptyug I.V.,A Institutskaya st
Chemical Society Reviews | Year: 2010

Magnetic resonance imaging (MRI) is a very powerful instrument used extensively in modern medical diagnostics because of its ability to look inside a body in a non-invasive and non-destructive way. Furthermore, MRI is more than just a single tool for extracting structural information. It is more of a sophisticated and versatile toolkit able to provide all sorts of useful information about the internal properties of an object under study and various processes within it, including heat and mass transport, composition and chemical transformations, in a spatially resolved mode. While a living body is different from a catalyst body or a reactor, the in situ and Operando studies in catalysis can clearly benefit from the use of this non-destructive toolkit as a powerful complement to other available spectroscopic tools. This tutorial review gives an introduction to the field and describes the examples of the applications of MRI to the studies of the preparation, deactivation and regeneration of solid catalysts and to the spectroscopy, thermometry and imaging studies of heterogeneous catalysts and model catalytic reactors performed during actual catalytic processes. © 2010 The Royal Society of Chemistry.

Zhdanov V.P.,Chalmers University of Technology | Zhdanov V.P.,RAS Boreskov Institute of Catalysis
Physics Reports | Year: 2011

In cells, genes are transcribed into mRNAs, and the latter are translated into proteins. Due to the feedbacks between these processes, the kinetics of gene expression may be complex even in the simplest genetic networks. The corresponding models have already been reviewed in the literature. A new avenue in this field is related to the recognition that the conventional scenario of gene expression is fully applicable only to prokaryotes whose genomes consist of tightly packed protein-coding sequences. In eukaryotic cells, in contrast, such sequences are relatively rare, and the rest of the genome includes numerous transcript units representing non-coding RNAs (ncRNAs). During the past decade, it has become clear that such RNAs play a crucial role in gene expression and accordingly influence a multitude of cellular processes both in the normal state and during diseases. The numerous biological functions of ncRNAs are based primarily on their abilities to silence genes via pairing with a target mRNA and subsequently preventing its translation or facilitating degradation of the mRNA-ncRNA complex. Many other abilities of ncRNAs have been discovered as well. Our review is focused on the available kinetic models describing the mRNA, ncRNA and protein interplay. In particular, we systematically present the simplest models without kinetic feedbacks, models containing feedbacks and predicting bistability and oscillations in simple genetic networks, and models describing the effect of ncRNAs on complex genetic networks. Mathematically, the presentation is based primarily on temporal mean-field kinetic equations. The stochastic and spatio-temporal effects are also briefly discussed. © 2010 Elsevier B.V.

Discover hidden collaborations