Biochemical oxidation of caprolactam-containing wastewater from the production of synthetic fibres

Conclusions The chemical mutagenesis method is recommended for use in local purification installations for cleaning up of caprolactam-containing wastewater.Use of this method permits one to carry out a biochemical clean-up of wastewater having a caprolactam content up to 600 mg/liter while increasing the oxidative power of the aeration tank by a factor of two.Translated from Khimicheskie Volokna, No. 6, p. 46, November–December, 1985.     

Preparation of heat-stable polypropylene fibres and their properties

Conclusions A method has been developed for preparing a modified polypropylene fibre by spinning from a mixture of polypropylene and a small amount of a thermoplastic acrylonitrile copolymer which contains a functional group which forms intermolecular chemical bonds during the fibre preparation process.It has been shown that in the given method of modifying PP fibre, its heat resistance is raised by 40–50°K.Translated from Khimicheskie Volokna, No. 3, pp. 51–52, May–June, 1985.     

Thermodynamic Simulation of the Behavior of a Carbonized Periclase Refractory with an Aluminum-Based Antioxidant

Using the method of Gibbs energy minimization, a computer-aided thermodynamic simulation of phase and chemical transformations in the MgO – C – Al – H₂O – air system at 298 – 2400 K is carried out to describe the behavior of a carbonized periclase material with an Al-based antioxidizing additive. The effect of temperature and environmental atmosphere on phase and chemical transformations in the material bulk and material's pore space is studied. The properties of a carbon matrix doped with aluminum are discussed.     

A study of the enrichability of Shchelkovo deposit dolomite by a photometric method

Conclusions A study of the optical and physical properties of Shchelkovo deposit dolomite ore shows that its petrographic varieties possess a significant contrast in color. The coefficient of reflection of dolomite (65–75%) differs significantly from that of silica concretions (20–25%), which are harmful impurities. Such a difference is the basis for application of photometric separation of dolomite ores.As a result of photometric sorting of the 15–20-, 10–15-, and 5–10-mm fractions of the dolomite ore, the harmful impurities were removed from it in the form of silica concretions, and the silicon dioxide content in the beneficiated concentrate was reduced to 1.1–1.2% from the 2.2–2.3% in the original. In chemical composition the concentrate meets the requirements for raw material used for the production of high-quality refractories.Despite the simplicity of beneficiation of dolomite ore by the photometric method with the large color contrast between the dolomite and the silica concretions, its separation is complicated by the fact that silicon is present in the dolomite itself (silicon dioxide content more than 1%). Therefore the production of material with a content of not more than 1.3% SiO₂ is difficult and requires careful observation of the sorting method and the use of equipment with a high resolving capacity.The introduction of the proposed flow plan for beneficiation, including photometric separation, will make it possible to supply the iron and steel plants of the European portion of the Russian Soviet Federative Socialist Republic with raw material for the production of high-quality refractories as the result of further use of Shchelkovo dolomite deposit.Translated from Ogneupory, No. 2, pp. 29–33, February, 1984.     

Acoustical method of studying structural changes during the swelling of fibres in liquids

Conclusions A procedure has been developed for direct study of the kinetics of structural changes in fibres during swelling in various liquids which used ultrasound.The possibility of using the ultrasonic method to study structural changes in fibres of various chemical structures during swelling has been demonstrated.Translated from Khimicheskie Volokna, No. 3, pp. 58–59, May–June, 1987.     

Properties of polyquinolines and of fibres based on them

Conclusions Two methods of spinning yans from polyquinolines of various chemical structures have been investigated.It has been shown that at the present stage of investigations it is advisable to use the dry-spinning method to obtain fibres from polyquinolines which have satisfactory physicome-chanical properties.Translated from Khimicheskie Volokna, No. 4, pp. 40–41, July–August, 1987.     

Determination of JP-8 components in soils using solid-phase microextraction–gas chromatography–mass spectrometry

Jet Propellant-8 (JP-8) is a military fuel associated with a large percentage of chemical exposures documented by the US Department of Defense. A fast and sensitive solid-phase microextraction–gas chromatographic–mass spectrometric (SPME–GC–MS) method has been developed for the determination of 34 ‘marker compounds’ found in JP-8. Linear ranges (R² > 0.99) were determined for each marker component and precision was measured (<16% RSD) for these components over four concentrations within each calibration range. The method was applied for the analysis of JP-8 components from soil. The use of SPME over other sample extraction techniques eliminates solvents, minimizes sample handling, and increases sensitivity.     

Gunite repair of refractory linings of machines for pellet firing

Conclusions It is found that the main wear-prone elements in machines for firing pellets are the coolers; changing these requires stopping the machine every 70–90 days on average, interrupting the normal course of the technological process. Repairs revealed the efficiency of the guniting method for repair of linings of firing machines, in comparison with poured concrete. The lifetimes of gunite concrete linings were 2–3 times greater: 220–240 days.Translated from Ogneupory, No. 4, pp. 49–52, April, 1980.     

Thermodynamic Simulation of the Behavior of a Carbonized Refractory

Using a Gibbs energy minimization method, a computer-assisted thermodynamic simulation of the MgO – C – H2O – air system at 298 – 2400 K is carried out to gain an insight into the behavior of a carbonized periclase material under operating conditions. The effect of temperature and the ambient gas medium on phase and chemical transformations in the bulk and pore space of the composite is studied.     

Density-functional based tight-binding calculations on zinc–blende type BC2N-crystals

The ternary system B–C–N has attracted considerable attention in recent years, as a result of potentially interesting properties of the phases in this system. A non-self-consistent, ab initio based tight-binding molecular-dynamics method, has been used to investigate the stability, structural and electronic properties of BC₂N-crystals with zinc–blende structure. We investigate cubic crystals with different BN–C₂ stacking sequences in the [100] direction. The competition between structural stress and chemical bond strength can be seen as crucial for the formation of real ternary crystalline structures or a segregation into two cubic phases: diamond and c-BN.     

A new solution technique for fluid–solid reactions

Fluid–solid reactions are very important in the chemical and metallurgical process industries. Several models described these reactions such as volume reaction model, grain model, random pore model and nucleation model. These models give two nonlinear-coupled partial differential equations (CPDE). When the fluid concentration is high (for example in liquid–solid reactions), the fluid mass balance must be written as an unsteady equation. There is not any analytical or approximate solution for these equations, due to its complex CPDE. In this work, a new solution technique (quantized method) has been applied to these unsteady state CPDE. The results of this method (conversion–time profiles) have been compared with some existing numerical solutions with a good accuracy. Therefore, this method can be used for rapid estimation of kinetic parameters from experimental data.     

Expenditure of heat energy in drying viscose textile yarns

Conclusions It has been found that the thermogravimetric analysis method is applicable for determining the expenditure of thermal energy in desorbing moisture from hydrocellulose textile fibres; it gives a quantitative evaluation of the fractional composition of the water sorbed by the yarns and of its bonding energy with the yarn matrix.The change in consumption of heat energy at various extents of drying of freshly-spun viscose textile yarns has been studied.It has been found that extensive drying of yarns, to a moisture content significantly lower than the conditioned values, that is, overdrying, requires elevated, unjustified expenditures of heat energy.Translated from Khimicheskie Volokna, No. 4, pp. 43–44, July–August, 1987.     

Calculation of Multiphase Liquid–Liquid Equilibrium and Automated Synthesis of the Structures of Phase Diagrams

A new method is suggested for calculating liquid–liquid equilibrium. The method requires the global structure of the phase diagram to be determined. An algorithm for the automated synthesis of diagram structures is developed.     

Mathematical Description of the Electrostatic State of Chemical Fibres with Consideration of the Forms of Intermolecular and Interfibre Interactions

A method for determining the electrostatic state of chemical fibres is developed. Mathematical dependences that allow determining the electrical capacitance of chemical fibres with different structural features and packages with longitudinal and transverse arrangement of the fibres are obtained. The inverse problem — finding the functional dependence of the dielectric constant of the investigated material on the initial capacitance — is solved.__________Translated from Khimicheskie Volokna, No. 1, pp. 56–58, January–February, 2005.     

Electrochemical behaviour of Cu-Zn-Al oxide catalysts in DMSO2 at 150°C

The electrochemical behaviour of Cu–Zn–Al oxide catalysts in a high-temperature solvent, dimethylsulphone (DMSO₂), at 150°C has been investigated. It has been shown that CuO electroreduction becomes easier and/or deeper in the Cu–Zn–Al oxide catalysts than in CuO alone. This electroreduction occurs at higher potentials, and the overall faradic yield decreases when CO₂ in dissolved in DMSO₂ on account of a strong interaction between the reduced species formed during the electronic transfer and CO₂. These results are consistent with the characterizations of the physical and chemical properties of these catalysts. They confirm that electrochemistry is a suitable method to determine the redox states of some copper industrial catalysts used in methanol synthesis.     

Electrodeposition of copper from pure cupric chloride hydrochloric acid solutions

Electrodeposition from CuCl2–HCl media has been investigated to establish a clean and direct method of copper extraction from cupric chloride solutions purified by anion exchange. The major difficulties of the process – cathode corrosion, CuCl precipitation and roughness of the deposit – were taken into consideration. To prevent contamination, no chemical agents or additives were used in the electrolyte preparation. The workable range of electrolyte composition was approached from a computer aided stability study of the different aquo- and chloro-complex copper species. Experiments suggested that coordination of the fundamental electrolysis parameters can ensure acceptable copper deposits and current efficiencies. A special method of agitation proved effective in improving the conditions.     

The Influence of Composition on the Chemical Durability of Glasses Based on Basaltoid Melts

The influence of the mineral composition on the chemical durability of glasses is investigated. Empirical relationships describing the composition dependences of the chemical durability of glasses in the diopside–albite, diopside–anorthite, diopside–orthoclase, diopside–quartz, and diopside–feldspar systems are derived.     

Molecular evolution of a defined DNA sequence with accumulation of mutations in a single round by a dual approach to random chemical mutagenesis (DuARCheM)

Directed evolution has paved the way to a new era of protein and nucleic acid molecules with improved and enhanced properties. The utmost important component of directed evolution is random mutations in a defined DNA sequence. The utility of random chemical mutagenesis in directed evolution studies is dwindling due to the inherent flaws with whole-organism mutagenesis and the in vitro approach. Here, we report a novel Dual Approach to Random Chemical Mutagenesis (DuARCheM) to introduce random mutations in a defined DNA fragment. DuARCheM involves in vivo chemical mutagenesis and in vitro genetic manipulations. The resulting library revealed an accumulation of mutations in its members. These results imply that the parent mutation is carried in the further generations within the same library. This method might help to change random chemical mutagenesis because the combination of in vivo and in vitro approaches mimics the amplification and mutation that is performed by PCR-based mutagenesis, and at the same time the mutations are confined to the desired gene. Moreover, the mutagen pressure is greater in chemical mutagenesis than in a Taq-polymerase-based error-prone system. Concomitant amplification and mutation in the DuARCheM method leads to a better spectrum of mutants because the plasmid construct is exponentially amplified in the presence of mutagen pressure, unlike in the in vitro chemical mutagenesis system in which the template molecule does not replicate. This work is able to nullify all the disadvantages that are associated with random chemical mutagenesis, and could make random chemical mutagenesis an indispensable tool in directed evolution studies.     

Adsorption of nonionic surface-active materials by polyamide fibres

Conclusions The possibility of using the polarographic method to investigate the adsorption of nonionic surface-active substances by the surface of polyamide fibres has been demonstrated.The differing adsorptive ability of the investigated NSAA is caused by their structure, the strength of the adsorbent-adsorbate chemical bond, orientation, and the form and length of the molecular chain.The results obtained may be used in the development of textile auxiliaries which will have a high adsorptive ability.Translated from Khimicheskie Volokna, No. 4, pp. 19–20, July–August, 1986.     

Cation exchange capacity methodology II: A modified silver–thiourea method

The silver–thiourea method for the determination of the cation exchange capacity (CEC) has been critically examined. The chemical instability of the exchange solution used causes silver sulphide precipitation on the walls of tubes resulting in a loss of the index cation. This produces misinterpretation and yields usually in an overestimation of the CEC. Furthermore, when expandable clay minerals are investigated excess adsorption occurs leading to unreliable CEC results dependent on solution/solid ratio and ionic strength of the exchange solution. A modified silver–thiourea method is proposed, which uses a chemically more stable exchange solution, eliminating silver sulphide precipitation and substantially lowering excess adsorption, which is abolished by additional washings. The results are comparable to the ammonium acetate method.