Mathematical simulation of the formation of liquid products from catalytic cracking gases over a zeolite-containing catalyst modified with Group VI and VIII metals

The kinetics of the formation of liquid products from catalytic cracking gases over a zeolite-containing catalyst in a flow reactor in the temperature range from 260 to 420°C at GHSV = 30–264 h^–1 and an on-stream time of 5–25 s has been investigated. A kinetic model for the process proceeding according to a likely scheme is proposed. The rate constants and activation energies of certain reactions involved in the process have been determined. A mathematical model of the process taking into account the mass and heat balances, as well as hydrodynamic conditions, has been developed. The concentration and temperature fields and the pressure over the catalyst bed height have been calculated. The target product yield on has been plotted as a function of the on-stream time.     

Y-type zeolites for the catalytic oxidative degradation of organic azo dyes in wastewater

Cobalt- and iron-containing catalysts active in the oxidation of organic dyes with hydrogen peroxide have been prepared from granular synthetic NaY and HY zeolites without a binder by ion exchange followed by heat treatment at 350–500°C. It has been demonstrated by X-ray photoelectron spectroscopy that cobalt and iron in these catalysts are in the form of Co²⁺ and Fe³⁺ ions on the support surface. The FeHY and CoNaY catalysts are most effective and stable in the oxidation of the anionic dye carmoisine in weakly acidic and alkaline media.     

A three-cell model of the initial stage of development of a proneural cluster

We construct a 9-dimensional nonlinear dynamical system that simulates the initial stage of interaction of three adjacent cells in the proneural cluster of Drosophila melanogaster. We describe the conditions of existence of three stable equilibrium points in the phase space of this system, list its other equilibrium points, and provide a biological interpretation.     

Polymerization of trimethylene carbonate and lactones in the presence of magnesium monoionolate: A comparative theoretical and experimental study

Using quantum-chemical calculations (DFT, program Priroda), the formation of a catalyst species on the basis of magnesium complexes with 2,6-di-tert-butyl-4-methylphenol is discussed. A comparative theoretical and experimental study of the ring-opening polymerization of trimethylene carbonate, 1,4-dioxanone, δ-valerolactone, and ε-caprolactone in the presence of the monoionolate magnesium complex is performed. It is shown that the calculated values of activation barriers correlate with the observed order of activity of cyclic esters. The maximum rate of polymerization is exhibited by trimethylene carbonate.     

Sonogashira reaction catalyzed by palladium isocyanide complex modified <Emphasis Type="Italic">in situ</Emphasis>

Palladium isocyanide complex modified in situ by addition of benzohydrazide as nucleophile was shown to catalyze Sonogashira reactions of phenylacetylene with iodobenzenes in refluxing ethanol in the presence of potassium carbonate. The reactions were complete in 2 h, and neither preliminary degassing nor protection from atmospheric moisture and oxygen was necessary. The yields of the cross-coupling products, unsymmetrical diarylacetylenes were only slightly lower than those obtained with the preliminarily prepared catalyst. The proposed procedure was used to synthesize a series of diarylacetylenes containing both electrondonating and electron-withdrawing substituents in the benzene rings.     

Imbricin,an Antifungal Antibiotic of Non-Medical Application: Preparation,Physicochemical Properties,Structural Features,and Industrial and Agricultural Uses (Review)

Published data on the preparation, physicochemical properties, and structural features of imbricin, an antifungal antibiotic of non-medical application, were systematically described. Directions of practical application of imbricin in various areas of industry and agriculture were summarized.     

Kinetics of the reaction of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylaniline with 1-bromoalk-2-ynes

Quaternization of N,N-dimethylaniline with propargyl bromide, 1-bromobut-2-yne, and 1-bromooct-2-yne were studied. It was shown that, with the lengthening chain of the substituent at the triple bond, the quaternization rate tends to increase.     

Mass Spectrometric Analysis of Microcystins from Cyanobacterial Biomass: Optimization of the Sample Preparation Procedure

The sample preparation procedure for determination of microcystins from biomass by the LC–MS method was optimized. Treatment of freeze-dried biomass samples with acetonitrile prior to the main extraction was effectively used for decreasing the amount of protein-like matrix compounds in extracts. Use of acetonitrile–water mixtures during the main ultrasound-assisted extraction allowed increasing the total microcystins amount in the resultant extracts compared to the traditional extraction using 75% methanol.     

Preparation and optical properties of composite materials based on polybenzimidazole and silver nanoparticles

Rigid-chain heat resistant polymers (with poly-2,2'-p-oxydiphenylene-5,5′-bisbenzimidazole as example) were impregnated for the first time with a silver-containing precursor in formic acid and in supercritical carbon dioxide. A procedure allowing the precursor reduction to silver nanoparticles both throughout the volume by thermal annealing of the films in the temperature interval 100–150°С and in the targeted mode using lasers operating at 405 and 532 nm was developed. It opens prospects for developing a process for production of heatresistant optical gratings and light guides. The reduces nanoparticles and their agglomerates have the size in the interval 50–200 nm and give a plasmon band in the range 450–460 nm.     

Effect of the alkylidene spacer and the p-tert-butylthiacalix[4]arene macrocyclic platform on the reactivity of the hydroxyl groups in the acylation reaction

Russian Journal of General Chemistry - A series of cone and 1,3-alternate p-tert-butylthiacalix[4]arenes tetrasubstituted at the lower rim simultaneously by the amide, ester, and carboxyl functions...