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  • 1995-1999  (246)
  • 1920-1924
  • 1996  (246)
  • Industrial Chemistry and Chemical Engineering  (246)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996) 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 1-10 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An account is given of the patented technique of the rotational particle separator for separating solid and liquid particles of diameter 0.1 μm and larger from gases. Attention is focused on the working principle, fluid mechanical constraints, particle design, separation performance, power consumption, dimensions, filter cleaning and costs. Furthermore, an overview is given of current developments to introduce this technique in industrial dust removal, in electricity generation and in the consumer goods market. The article concludes with a summary of the feature which distinguish this technique from existing filtering methods.
    Additional Material: 9 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 324-336 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article presents gas kinetic calculation methods for the energy transport in hydrogen/ air and methane/ air mixture. The total molecular heat conductivity as well as its various shares are calculated and discussed for a temperature range of 400 to 3500 K and for a pressure of 105 Pa. The variation of the air/ fuel ratio under the conditions of chemical equilibrium is also investigated. As opposed to our previous article, an extension of the Chapman-Knskog method which goes beyond the classical 1st approximation for elastic collisions is applied for the evaluation of suitable calculation methods. This is carried out following the method for strong relaxing thermal nonequilibrium according to Brun. The equations applied in this work are simplified formulations for the proximity to equilibrium. The method for the evaluation of the parameters of the inelastic collision and some chosen results are presented. A discussion of the various shares of the molecular heat conductivity emphasizes the considerable influence of the diffusion and the thermal diffusion processes in fuel/ air mixtures compared to the Fourier heat conductivity.
    Additional Material: 20 Ill.
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  • 4
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper represents an attempt to explicitly map the conceptual activities which constitute a process design task into a series of well-posed, complete and general numerical procedures. In spite of the fact that there is substantial number of design manuals and design procedures which process engineers can consult to choose the most proper approach to a particular problem, there is a remarkable lack of generality on the one side (procedures which apply to the design of a wastewater treatment process cannot be used even in principle to design a fluidized bed system), and an obvious receptivity on the other side (all procedures involve mass and energy balances at some point). With the advance of numerical techniques, virtually every procedure has been computerized, so that engineers can avail themselves of a multitude of computer tools in the majority of their process design activities: as a result of the lack of coordination among different producers though, the situation for what codes are concerned is very confusing: there are many codes which perform nominally the same task, giving (sometimes substantially!) different results when applied to the very same problem; each code sue its won set of property tables, its own I/O format, etc. Finally, with very few exceptions, these codes are not mutually compatible, i.e. the output from any of them cannot be used as the input to any of the other, not only because of the respective formats, but rather because the quantities taken to represent a certain physical process are not the same in different codes.This is a very unsatisfactory state of affairs, both for the final user and for the software producer. Unfortunately, this seems to be a problem for which commercial, technical and historical reasons make it very difficult to find a solution in the short term. The author is convinced that an early exposure to this problem and to a new approach to its solution can only benefit our engineering students, and has therefore endeavored, together with his coworkers, to devise a “modular approach” to the solution of process simulation problems. The material presented here has been originated by a series of lectures and seminars developed in the last three years for master and doctoral level students in Mechanical Engineering. The result of this “distillation” process maybe yet unripe, as they are definitely not complete: but the implications, also in terms of practical application, are very promising, and the approach deserves more attention in the future.The order of presentation of the material is historical/logical: it beings with the old fashioned slide-rule calculations and proceeds towards the most recent developments of AI base methods. The path is made clear from the very beginning: we are trying to extract from the various engineering activities all the essential knowledge which pertains to the engineer himself, with the final goal of transferring this body of knowledge - in some form suitable to machine communication - to a “universal-process simulator”, which can then be applied with a high degree of confidence to variety of particular process simulations.
    Additional Material: 9 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 209-214 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method for the prediction of velocity and path length components for two-dimensional particle motion is developed for stagnant and slowly moving gas. The numerical algorithm appears much more straightforward and more efficient than those previously developed on the basis of simplified analytical methods. In the case of particle motion in a flowing gas, several limitations of the method occur. The method of limit estimation is briefly described.
    Additional Material: 9 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 215-221 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The growth of a thin liquid film surrounded by gas pocket(s), undergoing absorption with a zero-order chemical reaction, has been simulated by an apt mathematical model in order to study the influence of various parameters involved. The solution has been obtained semi analytically using Goodman's integral method and solving the resulting differential equation by a fourth-order Runge-Kutta numerical integration algorithm. The computations reveal the strong dependence of film growth on reaction rate, diffusivity, and molar volume whereas the effect of gas-pocket volume and initial film thickness are moderate.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 243-248 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Heat transfer from a buried pipe carrying a flowing liquid is analysed using a 3-dimensional geometry, transient modeling and numerical methods. The pipe is buried horizontally in soil whose initial surface temperature is assumed to be below that of the bulk soil and the pipe, and also below the freezing temperature of the liquid. The problem is solved using string-intersected-boundaries and a three-level alternating-direction-implicit finite-difference method. It is possible to predict the time taken for the fluid anywhere in the pipe to fall to its freezing point. The minimum burial depth needed so that the pipe does not freeze is also predicted. The simulation was run on an ordinary mainframe computer with very small computation times. The package developed can be used by designers such as pipeline, plant and water distribution engineers.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 249-262 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general procedure for the determination of empirical rates and kinetic parameters of irreversible, constant volume reactions is presented which is clearly superior to the conventional methods of kinetic analysis. By nonlinear regression of the integrated potential rate equation for stoichiometrically independent reactions of n the order, the empirical pre-exponential factor, activation energy, and reaction order are obtained. The regression equation relates explicitly the final concentration of the reference component not only to the time parameter of the reaction but also to the initial concentration. This includes an integral method for the determination of reaction orders in concentration. Two limiting cases are treated - the stoichiometric mixture of reactants and a mixture with one reactant in large excess. By analysis of standard Hougen-Watson rate models the dependence of empirical reaction orders on experimental conditions and simulated rate parameters is evaluated. By grouping the data into ranges of monotonous concentration change, conversion rates and rate parameters of reactions with changing volumes are calculated in a less rigorous deduction. The simplified interpretation of published experimental data is demonstated for the total oxidation of methane on Pd-catalysts and the dehydrogenation of cyclohexanol on ZnO.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 263-271 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Catalyst surface characterizations have been carried out to investigate the role of dispersion on catalyst activity and to probe the occurrence of oscillations in coking levels with cycle number generally observed during multiple deactivation and regeneration schemes. The titrations were done, cycle by cycle, at 430°C after oxidation and at the same temperature (430°C) after reduction at 500°C. Results show the usually observed trend - that the dispersions after oxidation are higher than those after reduction. The average decline in dispersion from oxidation to reduction was calculated to be 39.25%. It was observed that the cycles with high toxic coke removal were characterised by high deactivation times. The deactivation times were still high even for cycles subsequent to those with low dispersion. At high dispersions the catalyst had short deactivation times, that is the small crystallites deactivate faster than large ones. The nature of reducebale coke and the efficiency of its removal is a much more determinant factor of catalyst activity than the level of metal disperision. Thus prolonged toxic coke reduction at the high temperature of 500°C, though resulting in an apparent lowering of dispersion, does not affect the quality of the catalyst. The dispersion before reduction could be retained on oxidation. Hence reduction at 500°C did not introduce sintering.
    Additional Material: 8 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 283-289 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A nonlinear unsteady state optimal control problem for a classical, constant diameter ethane thermal cracking reactor is formulated and solved. The process is represented by a pseudo steady state mathematical model, consisting of mass and heat balance, pressure drop, and coking equations. The performance index is of an economical nature, representing the global benefit of reactor operation over a constant operating time. As control variables, the space and time dependent skin tube temperature, the time dependent steam to hydrocarbon ratio, and the time dependent feed flow rate were considered. The results are in agreement with the process physicochemical and technological fundamentals.
    Additional Material: 5 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996) 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 272-282 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A chain growth model for heterogeneous secondary reactions is developed for the pyrolysis of large wood particles and the parameters determined by nonlinear optimization. The model takes both the volatile retention time and cracking and repolymerization reactions of the vapours with the decomposing solid as well as sutocatalysis into consideration. The extent of the secondary reactions is strongly influenced by the time and the ratio of the autocatalytic (propagation) reaction rate to noncatalytic (initiation) reaction rate. The wood which has a higher value of the autocatalytic/noncatalytic ratio also has a higher exothermic heat of reaction and yields a higher amount of final char residue. This fact confirms the heterogeneous secondary reactions lead to carbon enrichment of the final residue and are accompanied with an exothermic heat of reaction. The lower activation energies of the initiation and propagation reactions as compared to primary reactions (competitive reaction model consisting of weight loss and char forming reactions) confirm autocatalysis in large particles. The sealed reactor studies of small quantities of fine wood samples show that heterogeneous secondary reactions and not lower heating rates in large particles are the main source of char formed during the thermal decomposition of large wood particles. The model predictions are in agreement with the weight loss and temperature versus time curves over a wide range of particle size and furnace temperatures.
    Additional Material: 10 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 291-298 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Reasons are given why the axial dispersion in a gas flowing through a packed bed may be influenced by the elasticity - or compressibility - of the fluid. To support this hypothesis, experiments have been done in a packed column at pressures from 0.13 to 2.0 MPa. The elasticity E of a gas is proportional to the pressure P and the compressibility to 1/P. The axial dispersion coefficients as determined were found to be a function of the pressure in the packed bed in the turbulent flow region of 3 〈 Rep 〈 150 if the Bodenstein number is plotted as a function of the particle Reynolds number. This is shown to be an artifact. The pressure influence is eliminated, if Bom, ax is plotted versus the ratio of the kinetic forces over the elastic forces ϱu2/E. Regrettably, Bom, ax seems to be independent of ϱu2/E. For the moment we only can conclude that Bom, ax in the turbulent region is a unique function of the velocity of the gas which flows through the packed bed. Although the fact that a constant Bo value is obtained when plotted against ϱu2/E, the experimental results are so intriguing we wanted to make them public already now. The experimental work proceeds.
    Additional Material: 15 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 299-307 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The results of simulations of direct concentration control of a distillation column in industrial scale are presented. Both controlled variables, the two product concentrations, are determined by on-line gas chromatographs and are characterised by high dead times of about 30 min. For the resulting scanning control of the product concentrations corresponding decentralised PI controllers were developed and applied. The control of the product concentrations developed presents a conventional DV structure and was exemplarily tested for disturbances in feed flow and feed concentrations. The calculations carried out exhibit a good time behaviour of the whole system. On this occasion it can be stated that the control quality could be clearly improved if a steady-state decoupling by output transformation was employed. In this case the results achieved are totally comparable to those of internal model control (IMC), which was in use at the production plant for over two years.
    Additional Material: 9 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 357-363 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Affinity separation can be achieved by batch and fixed bed modes. Mathematical models including film mass transfer, intraparticle diffusion, and reversible reaction are formulated for both fixed bed and batch adsorption processes. Orthogonal collocation method is used to numerically evaluate the performance of batch and fixed bed adsorption. The efficiencies are evaluated in terms of both the solute recovery and adsorbent utilization. The effect of the following parameters is simulated for the comparison purpose: solute concentration, reaction kinetics, ligand content, and particle size. Fixed bed mode is found to be efficient.
    Additional Material: 9 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 378-385 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The present paper deals with a novel hydrogen sulphide abatement process applying a combined chemical-biological process. The authors already dealt with this subject in the paper “Biotechnological H2S gas treatment with Thiobacillus ferrooxidans” [1], previously published in Chemical Engineering and Technology. This study, in particular, deals with over all process test runs in a laboratory scale plant with a single-stage immobilised biomass reactor.
    Additional Material: 7 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 386-389 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Numerical results are presented for a contraction flow of a non-Newtonian fluid. In this work a new finite-volume algorithm was used and various non-Newtonian fluid models (with and without elasticity) were studied. The results are discussed and compared to experimental results obtained with a dilute polymer solution.
    Additional Material: 4 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 364-372 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Calcination and carbonation behaviour of dolomite has been studied in a pressurised thermo balance at pressures in the range of 1.1 to 2.3 MPa and for temperatures ranging from 730 to 840°C. The atmosphere consisted of nitrogen containing up to 20 vol.-% carbon dioxide. The calcination of dolomite has been studied as a function of temperature, particle size, and Pco2. An investigation concerning possible mass transfer restrictions for the experimental system and a model investigation of the calcination rate in CO2 atmosphere has been made. Further, the effect of calcination on the BET surface and the BET surface including the surface structure due to successive temperature cycles has been studied. The temperature for the initialisation of calcination of dolomite in CO2 atmosphere was independent of both Pco2 and the particle size. No conclusive indications on mass transfer restrictions have been detected for the experimental system. A significant difference in calcination rate as a function of particle size existed for decomposition in CO2 atmosphere. A model for homogeneously progressing chemical reaction parallel with a shrinking core chemical reaction together with a mass transfer control mechanism was found to describe the calcination rate in CO2 atmosphere most accurately.
    Additional Material: 6 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 373-377 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments on thermal decomposition of calcium carbonate were carried out in a thermogravimetric analyser under non-isothermal conditions of different heating rates (10 to 100°C/ min). A new technique for determining the kinetic parameters from non- isothermal thermogravimetric data was described. The activation energy and frequency factors were determined from the proposed method and also by the widely used Coats and Redfern method. The kinetic compensation effect between the activation energy and frequency factors obtained from both the methods were found to be very consistent and are in very good agreement with the literature values. The activation energy and frequency factors were also determined from isothermal experiments in the temperature range from 680 to 875°C. The activation energy and frequency factors determined from isothermal data using initial rate method were also found to be in very good agreement with the above results. It is also found that the kinetic parameters determined by isothermal analysis were consistent with the values determined by non-isothermal analysis.
    Additional Material: 5 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996) 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 21
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 398-404 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Affinity separations rely on the highly specific binding between a protein in solution and an immobilized ligand to achieve a high degree of protein purification. A mathematical model including convection, diffusion, and rate kinetics is formulated to analyze the design and operation of affinity membrane bioseparation. The model equations are solved by orthogonal collocation method. Danckwerts' boundary conditions are used. The results obtained from model simulation show that the breakthrough of the protein is significantly influenced by Péclet number, feed protein concentration, Ligand number, Damköhler number, membrane thickness, and flow rate. Breakthrough profiles are quantitatively discussed in terms of protein recovery efficiency, ligand utilization efficiency, thickness of unused membrane, and width of the mass transfer zone.
    Additional Material: 8 Ill.
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  • 22
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 405-409 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dynamic model incorporating biomass growth and liquid hold-up evolution is developed to describe a fixed bed bioreactor operation with cocurrent upflow of water and air flows. The model permits to predict cycle time and optimal operation conditions for high substrate removal and long cycle times. Simulation results are compared with published experimental results and show good model accuracy.
    Additional Material: 5 Ill.
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  • 23
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 391-397 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this paper the simulation of hybrid processes containing membrane units will be discussed. For this purpose a user-defined module for simulation and design of membrane processes was implemented into the simulation program AspenPlus.The advantages can be summarized as follows:-any combination of membrane processes with all other units already implemented in AspenPlus is possible, including internal recycle streams-utilization of the physical property models and data bases of AspenPlus is possible- cost and sensitivity analysis can be performed.These benefits are demonstrated in detail for a membrane vapor recovery unit for the treatment of tank farm off -gas, for a two-stage reverse osmosis plant for organic/-organic separations and for a combination of distillation and pervaporation for the separation of a dimethylcarbonate/methanol mixture.
    Additional Material: 8 Ill.
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  • 24
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 410-419 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: General simple criteria to predict and analyze the influence on trickle-bed reactors behavior of three phenomena, namely, plug flow deviations, external wetting efficiency and external mass transfer resistance, are developed. Criteria predictions are compared with results arising from a comprehensive mathematical model widely employed to describe trickle-bed reactors behavior and with other particular criteria reported in the literature. Present criteria applications to different sets of experimental data exemplify their practical utility for various actual situations and verify their validity. Besides, they constitute simple tools to diagnose detrimental on trickle-bed reactors operation.
    Additional Material: 4 Ill.
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  • 25
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 420-424 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new continuous-flow recycle microwave reactor suitable for organic synthesis has been developed to handle 0.51 quantities of reagents. The apparatus, which is designed for laboratory use, operates at atmospheric pressure in open- or closed-loop mode. It is fitted with a temperature control system. We describe this novel reactor and illustrate its efficiency with examples of organic syntheses carried out using both homogeneous and heterogeneous reactions.
    Additional Material: 4 Ill.
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  • 26
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 425-431 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Local mass transfer studies have been carried out in an external loop airlift reactor and indicated the existence of significant non-uniformities in aeration capacity in the various sections of the reactor. The traditional assumption of a single well mixed unit with a single kL a value for external loop airlift reactors was found to be poor and cannot represent adequately the reactor as a whole. The liquid head in the gas/liquid separator was found to have a significant negative negative effect on the local mass transfer coefficient kL a. Visualization of flow patterns showed the existence of strong vortices in the riser and downcomer which contributed to a reduction in local aeration capacity. Mass transfer experiments in an aerated tank showed that the aeration capacity can be reduced by half in viscous media but improved significantly in the presence of salts.
    Additional Material: 9 Ill.
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  • 27
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 432-437 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The wetting characteristics of fine powders play an important role in a variety of processes. The most important way of characterising the wettability of a fluid/fluid/solid system is to measure the contact angle. This paper describes a relatively simple method for the determination of the contact angle on powdery materials. The technique involves the measurement of the dynamic contact angle which is formed when a liquid drop is placed on a horizontal porous surface. On the basis of the measured dynamic contact angle as a function of time an “apparent” static contact angle has been defined, which gives a measure of the wettability of porous solid systems by analogy with the wetting of non-porous solids. Determinations with glass beads and NaCl-powders as the test materials indicate that the measured value depends on the particle size of the powder, the porosity and the temperature. It was concluded that the capillary penetration of the liquid droplet into the porous media itself influences the wetting characteristics.
    Additional Material: 12 Ill.
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  • 28
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 448-455 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model has been developed to simulate the operation of an absorption-driven multiple-effect evaporator. The model is based on mass and enthalpy balances and heat transfer rate equations of the various components of the system. The model has been validated by comparing model predictions to experimental results from the operation of a four effect absorption-driven falling film evaporator coupled with a two-effect regenerator which operated using solutions of sodium hydroxide as an absorptive medium. The model predictions are in satisfactory agreement with the experimental results.
    Additional Material: 10 Ill.
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  • 29
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 337-346 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A unified gas/ solid reaction model has been formulated for multi reactions with multi gas and solid species. The transient formulation has been followed by finite-difference method and subsequent solution via an iterative procedure. The simulation produces intermediate results for concentration profiles of various components and pressure and temperature distribution, in addition to various structural parameters within a reacting pellet. The effect of structural parameters is analysed. The general formulation allows homogeneous and heterogeneous reactions. Solid state processes can also be accommodated.
    Additional Material: 12 Ill.
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  • 30
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A critical comparison of the strength and weakness of two optimization strategies for thermochemical process is made, i.e. pinch analysis and exergy analysis. Although both methods have a unique root, i.e. the minimization of the exergy losses, pinch analysis has evolved to become an instrument of direct and optimal design of a heat exchanger network while exergy analysis as such does not give an indication about process optimization. In combination with an adequate simulation code of a process, however, it can help to find the optimum process structure.
    Additional Material: 5 Ill.
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  • 31
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996) 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 32
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 197-202 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Interfacial properties exert a fundamental influence on fluid/liquid separation processes, with the interfacial tension being an important quantity associated with mass transfer and mutual solubility of participating compounds. A better understanding of transport phenomena is achieved by obtaining interfacial tension data under different conditions of pressure and temperature and as a function of time. Generally, interfacial tension decreases with increasing pressure due to increased adsorption of the compressed fluid at the interface. In the case of considerable mutual solubility, interfacial tension further decreases with time as mass transfer into the bulk phase proceeds. Prediction of colloidal behaviour in a separation process requires acquisition of additional information on the presence of surfactants.
    Additional Material: 10 Ill.
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  • 33
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 222-232 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The generalised thermal parametric sensitivity criterion is applied to the thermal behaviour of the esterification of 2-butanol with propionic anhydride in a batch reactor under isoperibolic conditions. The reaction is catalysed by sulphuric acid, and the study covered the effects of both catalyst concentration and, in the absence of catalyst, jacket temperature. The experimental location of regions of parametric sensitivity agreed well with theoretical predictions. However, the process conditions that meet conventional standards for safe process design fall into the supercritical sensitivity region of the parametric model. This apparently contradictory result is discussed. The usefulness of the parametric sensitivity approach is illustrated by practical examples of scale-up and heat transfer in reactions prone to thermal runaway.
    Additional Material: 8 Ill.
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  • 34
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The optimal layout of a chemical plant is determined by both economic and environmental aspects. The mathematical approach to this problem is given by representing the process through a superstructure, including any foreseeable process topology. It is described by integer variables, whereas real variables arise from the unit models and the thermodynamic calculations. By including process constraints and an objective function, a Mixed Integer Nonlinear Programming (MINLP) optimization problem is postulated. In this paper MINLP algorithms are combined with a technique for the exergy analysis of chemical processes for the preliminary screening of process alternatives. The exergy analysis as a screening technique is advantageous due to a significantly smaller amount of required data and computing time, compared with true optimization, including cost estimation at an earlier stage of process synthesis and analysis. Thus, a broader solution space can be examined. The subsequent cost analysis has then only to be focused on a reduced set of parameters.
    Additional Material: 5 Ill.
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  • 35
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 233-239 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hybrid knowledge-based system proposed in this paper consists of a “stiff” segment, viz. the expert system based on the object-oriented approach, and a flexible part, viz. the neural network. Some of the input parameters of the problem and output parameters of the “stiff” system are presented as the fuzzy numbers. Detailed information is also presented about the development of the neural network. The most evident advantages of the proposed introduction of a hybrid architecture of the knowledge-based system are a faster evaluation and generation of design alternatives and support of systematic searches and storage of experience. In addition, the resulting ability to extrapolate results would be unattainable with separately acting stiff and flexible systems. A system for the estimation of the parameters of a mixing system for wastewater treatment is presented as an example to illustrate the principles of the hybrid system.
    Additional Material: 2 Ill.
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  • 36
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 240-242 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Pumping characteristic of an agitator in a tube is necessary of the calculation of its pumping capacity in configuration in the vessel with a draught tube. The general dimensionless equation of the pumping characteristic suitable for the higher Reynolds number region was derived by inspection analysis of basic equations. The new dynamic experimental method for determination of pumping characteristics is put forward. The application of this method is illustrated on a special three-blade axial-flow impeller.
    Additional Material: 5 Ill.
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  • 37
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 34-38 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We developed the oxidation reaction of Cu(I) ion in aqueous hydrochloric solution by oxygen in a gas-lift capillary bubble column. The method of gas-liquid absorption with chemical reaction was used. Test data confirmed that the rate constant of the reaction is strongly affected by solution compositions, and that chloride ions induce an inhibition effect. The kinetical orders found are equal to 1 and 2 for oxygen and Cu(I) respectively. The influence of temperature on reaction rate constant showed the existence of a maximum value between 303 and 313K. The effect of gas-liquid of gas-liquid system on the liquid-side mass transfer coefficient kL was also investigated.
    Additional Material: 6 Ill.
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  • 38
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    Chemical Engineering & Technology - CET 19 (1996), S. 39-42 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new Paradigm has been developed fro the prediction of maximum stable diameter of viscous drops in turbulent dispersions using the Voigt model. The model assumes that a drop would break if its deformation reaches unity. The prediction from the model compares quite well with the available experimental results.
    Additional Material: 4 Ill.
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  • 39
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 65-66 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The scale-up of benzoyl peroxide initiated copolymerisation of styrene and butyl methacrylate is studied here. The reaction is carried out in reactors of 3, 10 and 100 1 volume. Increasing the reactor size increase the weight average molecular weight and broadens the molecular weight distribution. Reducing the agitator diameter broadens the molecular weight distribution.
    Additional Material: 2 Ill.
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  • 40
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    Chemical Engineering & Technology - CET 19 (1996), S. 50-64 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Three-Phase fluidized bed bioreactors have advantages over conventional chemical reaction systems. There is a lack of agreement over most major operational conditions, and a wide range of design variables are open to question. A large body of recent work in the field has been reviewed, with a degree of historical comparison and discussion.It has been found that aspects of fluidized bed biofilm reactors of vital importance include: choice of solid media, gas and liquid loadings, bacterial type and reactor mechanical design. A large proportion of the work in the field of three-phase fluidization is non-biologically specific, or not tested on a bacterially inoculated system.The majority of three-phase fluidized bed bioreactor work is in the field of water treatment. Although this work has highlighted the potential for use of bio-fluidized beds for this application, there are still specific problems hindering the large scale industrial acceptance of three-phase fluidized bed bioreactors.
    Additional Material: 2 Ill.
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  • 41
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The performance of a packed-bed biological reactor has been analysed under sinusoidal variations of substrate concentration and temperature for zero-order, first-order and Michaelis-Menten kinetics. The model equations were solved by the method of orthogonal collocation. The results show that the cyclic steady-state conversion is not affected by cyclic variations in the feed concentration. However, cyclic temperature variations with an amplitude of 20°C significantly decrease the mean exit concentration for zero-order and Michaelis-Menten kinetics compared to the constant-temperature case. The approach to cyclic steady-state conditions is estimated to be somewhat flower for zero-order kinetics than for the other kinetics models investigated. We conclude that temperature variations during the day or changes in the performance of upstream plant will not adversely affect the performance of a packed-bed biological reactor.
    Additional Material: 14 Ill.
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  • 42
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    Chemical Engineering & Technology - CET 19 (1996), S. 67-74 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the field of fine chemicals batch process the implementation of synthesis paths results most often in the determination of the optimal operating conditions on a bench scale apparatus; successive scale-ups are then handled in an empirical way.For multi-phase reactions, this approach can be limited due to the coupling between the chemical kinetics and the physical kinetics of the mass transfer. This work proposes a more rational approach for the overall synthesis of Amiodarone, a widely used anti-arrhythmic drug produced by a liquid/liquid/solid reaction. After analysing the reaction scheme and identifying the limiting steps of the process, a simplified model is proposed to describe the overall process kinetics. The latter is used to model a continuous pilot loop-reactor packed with static mixers.
    Additional Material: 9 Ill.
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  • 43
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996) 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 44
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 79-88 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this paper a novel process for biotechnological abatement of hydrogen sulphide is presented which details the fundamentals of chemical and biological phenomena involved. The process is based on the combination of two steps to form a closed cycle which has special enviornmental advantages. The chemical step corresponds to the abatement reaction itself with absorption of the gas in a ferric solution. The biological step is related to the regeneration of the absorbing solution by means of specific bacterial strains. Particular interest is devoted to the biological kinetics of the regeneration stage, where several inhibition phenomena appear, and are also related to parameters such as temperature and pH. Results of experimental runs of gas absorption in a laboratory scale plant are also described.
    Additional Material: 12 Ill.
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  • 45
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    Chemical Engineering & Technology - CET 19 (1996), S. 75-78 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The process of recrystallization of apatite phosphogypsum (PHG) in a solution ammonium sulphate (AS) with the subsequent decomposition of the binary salt was investigated and the resulting highly dispersed products with a low P2O5 content have been discussed. The following effects were examined: (NH4)2SO4 concentration, the quantity of ammonium sulphate, the reaction temperature of phosphogypsum with (NH4)2SO4 solution, the time of treatment of phosphogypsum with (NH4)2SO4 solution and the decomposition of the binary salt, as well as the liquid/solid ratio for the binary salts, Based on the results of the chemical and X-ray analysis, it was established that, depending on the technological conditions of the process of recrystallization, binary salts of (NH4)2SO4·CaSO4·H2O and of (NH4)2SO4·CaSO4·H2O and of (NH4)2SO4·5 CaSO4·H2O were formed. As a result of the investigations carried out, a product with a low P2O5 content, suitable for direct processing to secondary products has been prepared.
    Additional Material: 1 Ill.
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  • 46
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    Chemical Engineering & Technology - CET 19 (1996), S. 89-95 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamic behavior of a Pt-Rh/CeO2-Al2O3 three-way catalyst (TWC) under pulsed flow operation conditions (intermittent mode), such as occur in a newly developed hybrid drive system, has been studied experimentally in a laboratory apparatus with simulated exhaust gas. The parallel hybrid system is based on the combination of an Otto-cycle engine with an electric motor and a flywheel providing a short-term energy storage. This configuration permits intermittent charging of the flywheel by the combustion engine which runs only during about 10% of the driving time. Each exhaust gas pulse (duration typically ca. 3 s) is proceeded by an air pulse, which results from the filling of the engine cylinders with air at start up and shut off. Experimental studies indicated that the air pulses have a negative impact on the performance of the catalytic converter, reducing the inherent benefits resulting from the intermittent operation mode of the combustion engine.Forced asymmetric λ-cycling during exhaust pulse was found to be most beneficial for improving catalyst performance. A simple reduced kinetic model derived from a Langmuir-Hinshelwood model for CO oxidation, which was extended by introducing CO and O2 equivalents to mimic the complex exhaust gas, was used to describe the dynamic behavior of the TWC. The model proved to be useful for finding the optimal λ-cycling conditions. Experiments with the real Otto-cycle engine exhaust proved that the reduced kinetic model is suitable for use in a closed loop λ-control.
    Additional Material: 8 Ill.
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  • 47
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    Chemical Engineering & Technology - CET 19 (1996), S. 97-102 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Suspension polymerization of styrene was performed in the loop reactor. In order to allow wide change to the polymer particle size, a sub impeller was included within the main impeller. The sub impeller served to increase the fluid velocity and to uniformly disperse the polymer droplets during polymerization.It was investigated how the double agitation method by the main and the sub impellers affected the transient droplet diameter distribution and the final particle size distribution. The particle size could be changed widely by the double agitation method without the decrease in degree of the uniformity of the particle size.
    Additional Material: 12 Ill.
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  • 48
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    Chemical Engineering & Technology - CET 19 (1996), S. 103-112 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Comparative calculations of several methods of characterization for three multicomponent mixtures that include paraffin, naphthene, and aromatic fractions are shown. Each method requires different experimental information about the mixtures but all use the numerical Gauss-Legendre quadrature. The results show that characterization making direct use of the TPB distillation curve is the most suitable approach for characterizing complex multicomponent mixtures.
    Additional Material: 9 Ill.
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  • 49
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    Chemical Engineering & Technology - CET 19 (1996), S. 113-116 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A three-step catalytic reaction (TSCR) mechanism is considered. It involves the steps of adsorption of two different reactants and the bimolecular reaction between adsorbed species. For this mechanism the rates of elementary reactions were assumed to be dependent on the surface coverages of two adspecies due to the repulsive mutual interactions between adsorbed species. The surface electronic gas model was chosen for the description of surface inhomogeneity. It is demonstrated that for such a TSCR mechanism sustained oscillations cannot exit. The application of the model to evaluation of kinetic data is discussed.
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  • 50
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    Chemical Engineering & Technology - CET 19 (1996), S. 347-356 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper deals with the modeling of toluene adsorption in a technical column of activated carbon in a low concentration range (2.6 to 3.4·10-3 kg/m3), which is usual for environmental applications. It is also concerned with methods of numerical solutions of the nonlinear partial differential equations (PDE), a modified control volume method was used to determine the PDE. Three nonequilibrium isotherm models are developed to describe mass transfer in a fixed bed of activated carbon (Degussa WS-4). The important parts of this paper are the simulation of the maldistribution of concentration and loading of the pollutant in the technical column, as a result of the flow velocity maldistribution and the study of the mass transfer mechanisms in a technical fixed bed. It is found that in a low concentration range, toluene adsorption in a fixed bed of activated carbon (Degussa WS-4) is an external rate-controlled process, thus surface diffusion cannot be neglected. The calculated results are in good agreement with the experimental ones. The measured effect of an earlier breakthrough near the wall-near zone has been calculated using the model.
    Additional Material: 17 Ill.
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  • 51
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    Applied Organometallic Chemistry 10 (1996), S. 75-75 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 52
    ISSN: 0268-2605
    Keywords: ceramic precursors ; poly[silylene-co-(2,4-disilapentane-2,4-diyl)] ; polycarbosilanes ; silicon carbide ; fibers ; thermal cross-linking ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel oligomers possessing a backbone formed of ((TRIPLE BOND)Si(SINGLE BOND)CH2(SINGLE BOND)Si(TRIPLE BOND)) and (SINGLE BOND)Si(SINGLE BOND)n units were prepared by the copolycondensation of bis(chlorosilyl)methanes and various dichlorosilanes in the presence of sodium, in refluxing toluene. The effect of the respective molar ratios of comonomers on the yields and the structure of the copolymers was investigated. The role of substituents on silicon atoms in the ability of these materials to provide convenient ceramic precursors upon pyrolysis was examined. When (TRIPLE BOND)Si(SINGLE BOND)H bonds were present, thermal cross-linking was readily performed and ceramics possessing variable C/Si ratios were prepared.
    Additional Material: 9 Ill.
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  • 53
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    Applied Organometallic Chemistry 10 (1996), S. 83-99 
    ISSN: 0268-2605
    Keywords: laser ; chemical vapour deposition ; thin films ; Si/C/H materials ; silacyclobutane ; 1,3-disilacyclobutane ; silicon carbide ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CO2 laser-induced infrared multiphoton decomposition (IRMPD) and SF6 photosensitized decomposition (LPD) of silacyclobutane (SCB) and 1,3-disilacyclobutane (DSCB) in the gas phase results in the very efficient deposition of Si/C/H and SiC materials, and it is inferred that the process is dominated by formation of transient silene; silene rearrangement to methylsilylene; silene and methylsilylene dehydrogenation; and polymerization of SiCHn (n 〈 4) species. The deposits are sensitive to oxygen.Decomposition and SiC formation are favoured with IRMPD experiments conducted with high-energy fluxes. The laser technique is promising for low-temperature chemical vapour deposition of amorphous SiC.
    Additional Material: 13 Ill.
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  • 54
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 363-367 
    ISSN: 0268-2605
    Keywords: diorganotin(IV) ; covalent templates ; macrocyclic ; acid anhydrides ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of new macrocyclic compounds have been prepared by treating di-n-butyltin(IV) dicarboxylates of diphenic acid (biphenyl-2,2′-dicarboxylic acid), thiodiacetic acid and maleic anhydride with succinyl, adipoyl and sebacoyl dichlorides. The compounds have been characterized with the help of elemental analyses and spectral data (mass, IR, IH and 13C NMR).
    Additional Material: 2 Ill.
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  • 55
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 389-392 
    ISSN: 0268-2605
    Keywords: regiospecific lithiation ; 2-furoic acid ; 5-ethyl-2-furoic acid ; butyl-lithium ; lithium di-isopropylamide (LDA) ; furonaphthoquinone ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of 5-ethyl-2-furoic acid with n-butyl-lithium in tetrahydrofuran gave regiospecific C-3 lithiation, whereas treatment of the same acid with lithium di-isopropylamide (LDA) afforded only starting material. The synthetic utility of dilithiated 5-ethyl-2-furoic acid has been demonstrated with the synthesis of two substituted 3-benzyl-5-ethyl-2-furoic acid derivatives which are key intermediates for the preparation of naturally occurring cytotoxic 2-ethylfuronaphthoquinones. Reaction of the C-3 lithiated species with two equivalents of benzaldehyde and subsequent reduction affored the corresponding 3-benzyl-5-ethyl-2-furoic acids. An alternative route to 5-ethyl-2-furoic acid has been described allowing for a more convenient preparation of longer-chain 5-alkyl-2-furoic acids.
    Additional Material: 2 Ill.
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  • 56
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    Applied Organometallic Chemistry 10 (1996), S. 415-420 
    ISSN: 0268-2605
    Keywords: cobaloxime ; radicals ; iodine atom abstraction ; ultrasound ; TEMPO-trapping ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High yields of alkyl radicals derived from alkylcobaloximes have been achieved using tungsten light (or in some cases ultrasound) radiation in both organic and aqueous media. These improved yields are obtained when pyridine (the usual base ligand) is replaced by suitably bulky lone-pair donors or water. The alkyl radicals so generated take part in iodine abstraction reactions with benzyl iodide giving benzyl radicals which may be trapped in near-quantitative yield with 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) or in good yield with lepidinium (4-methylquinolinium) trifluoroethanoate or lepidinium camphor-10-sulphonate. The usual drawbacks of cost and tedious work-up procedures associated with the more commonly used organotin hydride reagents are avoided.
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  • 57
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    Applied Organometallic Chemistry 10 (1996), S. 605-622 
    ISSN: 0268-2605
    Keywords: phtholocyanines ; metals ; macrocycles ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Additional Material: 8 Ill.
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  • 58
    ISSN: 0268-2605
    Keywords: chemiluminescence ; ion chromatography ; luminol ; heteropoly acid ; arsenic(V) ; germanium(IV) ; phosphorus(V) ; silicon(IV) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A flow-injection chemiluminescence (CL) method has been proposed for sensitive determination of arsenate, germanate, phosphate and silicate, after separation by ion chromatography (IC). The post-column detection system involved formation of heteropoly acid in a H2SO4 medium before the CL reaction with luminol in an NaOH medium. For separation, heteropoly acid formation and the CL detection reaction, pH requirements were not compatible. When present as a heteropoly acid complex with molybdenum(VI), ger- manium(IV) and silicon(IV) caused CL emission from oxidation of luminol, and such a CL oxidation of luminol was observed analogously for arsenic(V) and phosphorus(V) but with the addition of metavanadate ion to the acid solution of molybdate. Good sensitivity for the three analytes arsenic(V), ger- manium(IV) and phosphorus(V) could be given by a single set of reagent conditions, chosen carefully. Another set was suitable for determining phosphorus(V) and silicon(IV). The minimum detectable concentrations of arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were 10, 50, 1 and 10 μg l-1, respectively. Linear calibrations for arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were established over the respective concentration ranges of 10-1000, 50-25000, 1-1000 and 50-1 μg l-1. The proposed IC-CL method was successfully applied to analyses of a seaweed reference material, rice wine and water samples.
    Additional Material: 3 Ill.
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  • 59
    ISSN: 0268-2605
    Keywords: selective reduction ; carbonyl compound ; sodium hydrogentelluride ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic aldehydes or ketones which have electron-withdrawing groups on the benzene ring were selectively reduced to the corresponding alcohols in good yields by sodium hydrogentelluride; common aldehydes such as benzaldehyde and tolualdehyde were inert.
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  • 60
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    Applied Organometallic Chemistry 10 (1996), S. 779-790 
    ISSN: 0268-2605
    Keywords: organotin ; N-acetyltriglycine ; N-benzoyltriglycine ; Mössbauer ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Di- and tri-organotin(IV) derivatives of N-acetyltriglycine and N-benzoyltriglycine (HA) were obtained by refluxing equimolar mixtures of the ligand and the organotin(IV) oxide or hydroxide in methanol or acetone. According to the spectroscopic data, triorganotin(IV) derivatives adopt a trigonal-bipyramidal structure in which the planar R3SnIV unit is bonded by a monodentate carboxylate group and a donor group, presumably the amide C=O. The reaction of HA with the appropriate diorganotin(IV) compounds gave both dicarboxylates R2SnA2, with six-coordinated tin, and dimeric tetraorganodistannoxanes {[R2SnA]2O}2, in which the tin atoms are essentially five-coordinated.
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  • 61
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    Applied Organometallic Chemistry 10 (1996), S. 199-208 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 62
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    Applied Organometallic Chemistry 10 (1996), S. 147-174 
    ISSN: 0268-2605
    Keywords: trifluoromethyl group ; aminoboranes ; trifluoromethyl boron compounds ; synthesis; reactions ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Additional Material: 40 Ill.
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  • 63
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    Applied Organometallic Chemistry 10 (1996), S. 283-295 
    ISSN: 0268-2605
    Keywords: boron ; carborane ; structure ; theoretical studies ; electronic energy ; isomers ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An ab initio study of the BC2H4 has been carried out. Several isomers have been studied: boron-ethylene complexes resulting from perpendicular and σ interactions, boron-methylcarbene type structures, open and cyclic insertion products with a B-H bond, and isomers with two B-H bonds. Geometries at the second-order Møller-Plesset level have been obtained for ten species, and their characteristics have been tested through computation of vibrational frequencies. Special attention has been paid to their molecular structure, trying to rationalize the bonding in these species, particularly in the case of cyclic isomers. Electronic energies have been computed at the fourth-order Møller-Plesset level. Our theoretical calculations predict that the global minimum is the H2BCCH2 isomer (2B2 electronic state), with the HBH plane perpendicular to the CCH2 moiety, and that it lies about 66 kcal mol-1 (276 kJ mol-1) below ground-state boron+ethylene. Nevertheless there are other isomers which are also quite stable and might be accessible to experimental detection, such as HBCHCH2 and H2BCHCH (both with 2A′ electronic states) which lie 8 (33.5) and 13 kcal mol-1 (54.4 kJ mol-1), respectively, above the global minimum, as well as two cyclic structures, the insertion product HBC2H3(2A″) and the boron-ethylene π-complex BC2H4 (2A1), which are relatively stable since they lie 12 (50) and 22 kcal mol-1 (92 kJ mol-1), respectively, higher than H2BCCH2.
    Additional Material: 16 Ill.
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  • 64
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    Applied Organometallic Chemistry 10 (1996), S. 175-182 
    ISSN: 0268-2605
    Keywords: boron nitride ; pyrolysis ; chemical vapor deposition ; aminoborane ; borazine ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Research efforts conducted in the Chemistry Division of the Oak Ridge National Laboratory on the preparation of polymeric precursors to boron nitride are reviewed. They evolved from the preparation of powders, which contained significant amounts of residual carbon, derived from the pyrolysis of aminoborane polymers to relatively pure films produced by chemical vapor deposition using polymeric cyanoborane as a single source. Interesting C/B/N films were produced from the pyrolyses of volatile borazine derivatives, and a polymeric borazine intermediate produced denser boron nitride (BN) compact bodies when used as a binder as opposed to bulk BN compressed without a binder. The challenges of producing boron nitride fibers have been defined.
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  • 65
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    Applied Organometallic Chemistry 10 (1996), S. 209-225 
    ISSN: 0268-2605
    Keywords: metal-carborane complexes ; sandwich complexes ; transition-metal complexes ; metallacarboranes ; multidecker complexes ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-metal sandwich complexes incorporating bifacially coordinated C2B3 planar carborane rings form a large and varied family of generally air-stable, highly robust compounds that feature multidecker stacking. As a group, these complexes offer a number of advantages that are potentially of interest in the development of new electronic, magnetic and/or optical materials. They are remarkably versatile, accommodating a wide range of metals and organic substituents; they are soluble in organic solvents and are typically resistant to air and moisture; they can be reversibly oxidized and reduced; in many cases they are paramagnetic, exhibiting substantial electron delocalization of the unpaired electrons between metal centers. Moreover, the small carborane starting materials can now be prepared in large (ca100 g) quantities, making the complexes readily accessible. A brief overview of this area is presented with emphasis on the systematic utilization of metallacarborane sandwich complexes in the construction of large multimetallic systems and studies of their electronic and molecular structures.
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  • 66
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    Applied Organometallic Chemistry 10 (1996) 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 67
    ISSN: 0268-2605
    Keywords: arsenic-containing ribofuranosides ; arsenosugars ; (2′R)-dimethyl[1-O-(2′,3′-dihydroxypropyl)-5-deoxy-β-D-ribofuranos-5-yl]arsine oxide ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Six arsenic-containing β-D-ribofuranosides, including the naturally occurring (2′R)-dimethyl[1-O-(2′,3′-dihydroxypropyl)-5-deoxy-β-D-ribofuranos-5-yl]arsine oxide, were prepared in multi-step reactions from D-ribose and tetramethyldiarsine. The synthetic procedure uses the early substitution of the hydroxy group with bromine at C5, subsequent attachment of a chiral three-carbon aglycone at C1, and final delivery of arsenic at C5. The synthesis provides a viable route for the preparation of multigram quantities of the natural product.
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  • 68
    ISSN: 0268-2605
    Keywords: organotin ; pyrimidin-4-one derivatives ; complexes ; cytotoxicity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The coordination behaviour of the diorganotin (IV) compounds R2SnCl2 (where R = Me, Ph) with 4H-pyrido [1,2-a] pyrimidin-4-one derivatives (L) has been described. The complexes R2SnCl2 · L obtained have been characterized physicochemically and spectroscopically. The pyrimidin-4-one ligands were found to coordinate with R2SnCl2 species in a monodentate fashion, mainly via the oxygen atom of the 4-one group or possibly via the nitrogen atom of the (SINGLE BOND)C(DOUBLE BOND)N linkage (the less sterically hindered nitrogen of the pyrimidine derivative) to give pentacoordinate tin complexes. Of the complexes selected to be screened against five tumour cell lines, some exhibited significant in vitro activity.
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  • 69
    ISSN: 0268-2605
    Keywords: triphenyltin ; carboxylate ; spectroscopy ; crystal structure ; fungitoxicity ; Ceratocystis ulmi ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four triphenyltin carboxylates formulated as o-Ph3SnOCOC6H4CH=N-Ar (Ar=C6H5; p-CH3C6H4; o-CH3C6H4; o-HOC6H4) were prepared and spectroscopically characterized. The crystal structure of o-Ph3SnOCOC6 H4CH=NC6H5 indicates that the tin atom, in each of the two molecules comprising the asymmetric unit, exists in a distorted tetrahedral geometry owing to an intramolecular acyl O. . .Sn contact. These new triphenyltin carboxylates display marked toxicity against the fungus Ceratocystis ulmi.
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  • 70
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    Applied Organometallic Chemistry 10 (1996), S. 471-476 
    ISSN: 0268-2605
    Keywords: Butyltin compounds ; extraction ; mussels ; analytical procedures ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three different sample pretreatment methods (methanolic HCl with or without tropolone and enzymic extraction) and two final determination procedures (GC-MS and GC-QFAAS) have been applied independently to the determination of butyltin compounds in two mussel samples polluted at different levels. The results obtained validate the sample storage and transport conditions as well as the analytical procedures.
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  • 71
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    Applied Organometallic Chemistry 10 (1996) 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 72
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    Applied Organometallic Chemistry 10 (1996), S. 557-577 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper provides a review of phthalocyan- ines suitable for the development of chemical sensors. Phthalocyanines may be utilized for different types of chemical sensors, including in particular electronic conductance sensors [such as semiconductive, field-effect transistor (FET), solid-state ionic and capacitance sensors], mass-sensitive sensors utilizing a quartz crystal microbalance (QCM) and surface acoustic-wave (SAW) sensors, and optical sensors. The phthalocyanines used are discussed in terms of their physical and chemical properties, as well as their sensitivity, selectivity and reversibility towards the detection of NO2 and organic solvent vapours. The interaction mechanism between phthalocyanine films and analyte molecules is also discussed.
    Additional Material: 8 Ill.
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  • 73
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    Applied Organometallic Chemistry 10 (1996), S. 649-660 
    ISSN: 0268-2605
    Keywords: naphthalocyanine ; ruthenium ; bridged ; oligomers ; solid state ; NMR ; conductivity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bridged 2,3-naphthalocyaninatoruthenium oligomers {[MacRu(L)]n} were synthesized and characterized using solid-state methods. For comparison, soluble t-butyl substituted phthalocyaninatoruthenium oligomers were prepared and their chain length examined by 1H NMR spectroscopy. The powder conductivities of all bridged compounds ([MacRu(L)]n) were measured and the dependence of the conductivities on the bridging ligands is discussed.
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  • 74
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    Applied Organometallic Chemistry 10 (1996), S. 579-590 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 75
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    Applied Organometallic Chemistry 10 (1996), S. 591-604 
    ISSN: 0268-2605
    Keywords: metal phthalocyanines ; redox reaction ; electrocatalysis ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Additional Material: 5 Ill.
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  • 76
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    Applied Organometallic Chemistry 10 (1996), S. 683-688 
    ISSN: 0268-2605
    Keywords: inorganic arsenic ; methanearsonic acid ; dimethylarsinic acid ; tetramethylarsonium salt ; arsenocholine ; microorganisms ; conversion ; degradation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sediments, as sources of microorganisms, were added to two kinds of media, 1/5 ZoBell 2216E and a solution of inorganic salts, which contained inorganic arsenic(III), inorganic arsenic(V), methanearsonic acid, dimethyl- arsinic acid, trimethylarsine oxide, tetramethylarsonium salt or arsenocholine. After 17 days of incubation at 20 °C, the arsenicals that had accumulated in the microorganisms were analysed by high-performance liquid chromatography (HPLC). While the more toxic arsenicals [inorganic arsenic(III), inorganic arsenic(V), methanearsonic acid, dimethylarsinic acid] were not converted in the microorganisms, trimethylarsine oxide and tetramethylarsonium salt were considerably degraded to inorganic arsenic(V), and arsenocholine to arsenobetaine. Arsenobetaine that had accumulated in the microorganisms was extracted and confirmed by thin-layer chromatography (TLC) and fast atom bombardment (FAB) mass spectrometry.
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  • 77
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    Applied Organometallic Chemistry 10 (1996), S. 757-760 
    ISSN: 0268-2605
    Keywords: Arsenic ; environmental standard ; river ; ground water ; earthquake ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arsenic contamination in river and ground water was investigated in the Inagawa area of Kansai district, Japan, from August to October, 1995. Arsenic has been continually detected at a level about 2 times higher than the environmental standard in the two tributaries of the Inagawa River, i.e. the Kimo and the Shio Rivers. The arsenic contamination was probably caused by the topographical change after the Great Hanshin Earthquake.
    Additional Material: 2 Ill.
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  • 78
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    Applied Organometallic Chemistry 10 (1996), S. 733-740 
    ISSN: 0268-2605
    Keywords: arsenic speciation ; seasonal change ; methylarsenical ; seawater ; sediment ; biological activity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The distribution of arsenic species, including trivalent methylarsenicals, was observed in coastal seawater of Tosa Bay and Uranouchi Inlet Japan. In Tosa Bay, most arsenic was dissolved in the inorganic form throughout the year and the concentration of total dissolved arsenic was higher than that in Uranouchi Inlet. The sum of methylarsenicals found in surface waters comprised 2-25% and 10-82% of the total dissolved arsenic in Tosa Bay and Uranouchi Inlet, respectively. In Uranouchi Inlet, seasonal variations in the concentrations of arsenicals were observed both in the water column and in surface sediments. The maximum concentrations of methylarsenicals appeared during summer, and became comparable to those of inorganic arsenicals in surface water. The concentration of trivalent methylarsenicals was usually low, and their seasonal changes seemed to be independent of those of the pentavalent species. The variations in methylarsenic(V) concentration did not coincide with those of chlorophyll a in either Tosa Bay or Uranouchi Inlet. These results suggested that methylarsenic(V) in natural waters was produced not directly by the activity of phytoplankton but through decomposition of organic matter by bacteria.
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  • 79
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    Applied Organometallic Chemistry 10 (1996), S. 795-795 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 80
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    Applied Organometallic Chemistry 10 (1996), S. 227-239 
    ISSN: 0268-2605
    Keywords: heteroborane ; cluster ; nitrogen ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Additional Material: 6 Ill.
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  • 81
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    Applied Organometallic Chemistry 10 (1996), S. 35-45 
    ISSN: 0268-2605
    Keywords: organotin ; esters of 2-mercaptopyridine-5-carboxylic acid ; 2-mercaptopyridine ; Mössbauer ; IR ; NMR ; crystal structure ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By reaction of diphenyltin(IV) chloride and triphenyltin(IV) hydroxide with esters of the 2-mercaptopyridine-5-carboxylic acid (OVERBAR)NH(CS)CHCHC(COOR)(/OVERBAR)CH (HTNME, R = methyl; HTNEE, R = ethyl; HTNIPE, R = isopropyl) the complexes Ph3Sn(L), Ph2SnCI(L) (L = TNME, TNEE and TNIPE) and Ph2Sn(TNEE)2 have been prepared and characterized by IR, NMR and Mössbauer spectroscopies. Moreover, the Ph2SnCl2/2-mercaptopyridine (HMP) system has been found to yield either the Ph2SnCl2(HMP)2 adduct or the Ph2SnCl(MP) complex.The structures of Ph2SnCl(TNEE) and Ph2SnCl(MP) have been determined by X-ray single-crystal diffraction studies. The two structures are similar. Both ligands behave as bidentate chelating groups forming a four-membered ring with an identical small N(SINGLE BOND)Sn(SINGLE BOND)S bite angle of 63.7°. The tin atom is pentacoordinated, presenting a severely distorted trigonal bipyramidal geometry with apical Cl(SINGLE BOND)Sn(SINGLE BOND)N angles of 155.0(2)° [Ph2SnCl(TNEE)] and 155.7(7)° [Ph2SnCl(MP)] and equatorial C(SINGLE BOND)Sn(SINGLE BOND)C angles of 114.9(2)° and 125.0(3)° respectively. On the basis of 119Sn Mössbauer data, all the complexes should present analogous structures except Ph2Sn(TNEE)2 and Ph2SnCl2(HMP)2, for which an octahedral coordination geometry with a trans arrangement of the phenyl groups can be proposed. The effect of dimethyl sulphoxide on Ph2SnCl(L) and Ph2SnCl2(HMP)2 is also discussed.
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  • 82
    ISSN: 0268-2605
    Keywords: Organotin compounds ; speciation ; high-performance liquid chromatography ; inductively coupled plasma-mass spectrometry ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An evaluation of reversed-phase high-performance liquid chromatography (HPLC) employing mobile phases compatible with direct coupling to inductively coupled plasma-mass spectrometry (ICP-MS) is described for the selective and sensitive detection of organotin species. The findings of this study are compared with established methods, employing ion-exchange chromatography.In order to achieve optimum performance, both the HPLC and ICP-MS were optimized for speciation work. The results from studies using various mobile phases for the separation of a range of tin compounds (inorganic tin, tributyltin, dibutyltin and monobutyltin) are discussed both in terms of resolution and compatibility with ICP-MS instrumentation. Tropolone, a commonly used complexing agent for organotin species, is also discussed with reference to the chromatographic separation of tin species.Finally, the role of isotope dilution analysis in conjunction with HPLC-ICP-MS for organotin speciation is described with respect to the European Community Standards, Measurements and Testing (BCR) certified material programme.
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  • 83
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    Applied Organometallic Chemistry 10 (1996), S. 77-82 
    ISSN: 0268-2605
    Keywords: gas chromatography ; flame photometric detector ; quartz tube ; butyltin species ; water analysis ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A flame photometric detector using quartz surface-induced tin emission was designed and evaluated for quantification analysis of butyltin species. It has been demonstrated that this quartz surface-induced tin emission, centred at 390 nm, is more sensitive than the commonly used gas-phase emission at 610 nm. The dependence of detector response on quartz enclosure was studied. The operational variables such as hydrogen-air flow rate, carrier-gas flow rate and purge-gas flow rate were optimized. An analytical procedure for speciation analysis of butyltin species in water using simultaneous hydride generation with sodium borohydride and extraction into dichloromethane was established. The detection limits (defined as the signals that equal three times the deviations of the noise) were 0.3 pg of Sn for tetrabutyltin (TeBT), 5 pg of Sn for monobutyltin (MBT), 18 pg of Sn for dibutyltin (DBT) and 2 pg of Sn for tributyltin (TBT), which are approximately 10- to 30-fold better than those reported for using more commonly used gas-phase emission centred at 610 nm.
    Additional Material: 3 Ill.
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  • 84
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    Applied Organometallic Chemistry 10 (1996), S. 125-133 
    ISSN: 0268-2605
    Keywords: organotin compounds ; electrospray ; mass spectra ; clusters ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The limitations of conventional gas chromatography-mass spectrometry (GC-MS) analyses for alkyl- and aryl-tin compounds are discussed, particularly the excessive fragmentation from electron impact (EI) ionization. Negative EI methods exhibit low ionization capabilities and are restricted to compounds with an electronegative centre, and are thus not suitable for general routine analysis. Liquid chromatography-MS (LC-MS) interfaces offer potential advantages in terms of reduced sample work-up since no derivatization is required. Electrospray techniques give reproducible mass spectra for each compound studied under fixed instrumental parameters. Changes in the cone/repeller voltages can radically alter the observed mass spectra. High-mass species were observed for each compound studied and tentative structures for these species are proposed.
    Additional Material: 5 Ill.
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  • 85
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 377-387 
    ISSN: 0268-2605
    Keywords: organotins ; toxicity ; algae ; submicrostructure ; counterions ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The inhibition by 20 organotin compounds (RnSnX4-n), which included some newly synthesized pesticides, of the growth of two green algae (Scenedesmus obliquus and Platymonas sp.) was studied. The influence of the counterion X group on the toxicity of organotins was discussed. The destruction of submicrostructures of the algal cell by organotins was viewed by micrography and electron microscope scanning. It was found that the toxicity of the organotins varied significantly according to their substitution. The order of toxicity is tri- ≫ di- ≥ mono-organotins. Within the same substituent series, the toxicity depends on the properties of both R and X groups. The larger and the more lipophilic the R group, the more toxic is the organotin. The influence of the X group is more complex: when X is a small easily ionizable group, it has little effect on the toxicity; however, when it is a large organic group, it does change the bioactivity of the organotin. Large organic groups may influence the polarizability of the central tin atom, and so change the toxicity of organotins.
    Additional Material: 12 Ill.
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  • 86
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 405-413 
    ISSN: 0268-2605
    Keywords: tributyltin ; embryo toxicity ; ascidians ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of tributyltin(IV) chloride (TBT chloride) have been tested on embryos of the ascidian Ciona intestinalis, at two different stages of development: (1) before hatching (coiled larval stage) and (2) 2 h after hatching (swimming larval stage). In vivo observations carried out with a light microscope showed that embryos at the coiled larval stage did not hatch following exposure to TBT chloride. Severe anomalies in the swimming larva, mainly concerning the morphology of the tail, which appeared twisted and squatter than in the controls, were observed. Such anomalies were also found at a functional level, i.e. contractile movements were poor so that the larvae appeared motionless. Ultrastructural investigations carried out using a transmission electron microscope (TEM) evidenced that the muscle cells were damaged. Modifications mainly occurred in mitochondria and myofibrils, i.e. the energetic and enzymic centres. This fact is probably the main cause of the loss of mobility of the larvae.
    Additional Material: 15 Ill.
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  • 87
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 437-450 
    ISSN: 0268-2605
    Keywords: siloxanes ; surfactant ; carbohydrate ; amino ; regioselective ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Branched siloxanyl-modified carbohydrate surfactants have been synthesized by coupling mono-, di- and poly-functional siloxanes to carbohydrate units either via a branched spacer or by attaching a separate modifying element to a straight-chained structure. Hydrophilic as well as extremely hydrophobic elements have been incorporated successfully. Siloxanyl-modified carbohydrates bearing a secondary amino function were alkylated in regioselective reactions by different epoxides ranging from glycidol- to siloxanyl-modified allyl glycidyl ether derivatives. Alternatively, carbohydrate-modified piperazinyl structures yielded cyclic subunits after alkylation. Structures bearing two identical hydrophilic groups are accessible by alkylation of carbohydrate-modified bisamides. The derivatives synthesized were characterized by means of GC, NMR and elemental analysis.
    Additional Material: 6 Ill.
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  • 88
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 469-469 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Type of Medium: Electronic Resource
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  • 89
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 477-484 
    ISSN: 0268-2605
    Keywords: Thio-organotins ; polypropylene stabilization ; tin-sulfur (Sn-S) bond ; oxidation ; hydroperoxides ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various thio-organotin compounds have been reacted with t-butyl hydroperoxide in order to determine whether this oxidation can be responsible for the stabilizing capacity of some thio-organotins towards polyolefin degradation. The kinetics of t-butyl hydroperoxide disappearance, in the presence of thiotin compounds, shows different reactivity according to the structure of oranometallic reagent. Product analysis indicates organotin oxide, dialkyl disulfide and t-butanol as major reaction products. The reactivity sequence towards hydroperoxide is the same as the order observed for polypropylene stabilization.
    Additional Material: 3 Ill.
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  • 90
    ISSN: 0268-2605
    Keywords: Adducts ; C. ulmi ; thiazolidin-4-ones ; Dutch elm disease ; IR spectroscopy ; Mössbauer spectroscopy ; toxicity ; triphenyltin Chloride ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several 1:1 addition compounds between triphenyltin chloride and 2,3-disubstituted thiazolidin-4-one ligands have been synthesized. Their molecular structure has been deduced using far IR and Mössbauer spectroscopies. In addition, molecular modeling of several of the complexes was used to explain the variation of the quadrupole splitting values in the Mössbauer spectra. The structures of the complexes were determined to be trigonal-bipyramidal with the three phenyl groups in the equatorial plane. However, the phenyl groups are not co-planar, on the basis of the observation of both the Sn-C (phenyl) symmetric and asymmetric stretching vibrations. The adducts were screened against the fungus Ceratocystis ulmi, the agent responsible for Dutch elm disease, and found to be effective in the inhibition of this fungus. The toxicity of the adducts varied with the hydrophobicity of the molecule. A direct correlation between substitution on the phenyl group on the thiazolidine ring and the toxicity of the compound was not observed.
    Additional Material: 2 Ill.
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  • 91
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 531-535 
    ISSN: 0268-2605
    Keywords: bile acids ; conjugated bile acids ; trimethylsilyl (TMS) derivatives ; GLC-MS analysis ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The trimethylsilyl (TMS) derivatives of a mixture of nine bile acids (six free and three conjugated), namely lithocholic, deoxycholic, chenocholic, cholic, hyodeoxycholic, ursodeoxycholic, glycodeoxycholic, glycocholic and glycochenodeoxycholic acids, have been prepared by a new, simple, efficient derivatization procedure, based on the use of a mixture of N-methyl-N-trimethylsilyl-1,1,1- trifluoroacetamide and 1-(trimethylsilyl)imidazole, as the silylating agent. The above-mentioned bile acids were completely trimethylsilylated on all hydroxyl and carboxyl groups whereas carbonyl and amino groups remained untouched.
    Additional Material: 3 Ill.
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  • 92
    ISSN: 0268-2605
    Keywords: phtholocyonines ; double clearing behavior ; discotic liquid crystal ; mesophase ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eight novel octakis(3,4-dialkoxyphenyl)- phthalocyanine derivatives, Cn-M (2, M=2H; 3, M=Ni; 4, M=Cu; a, decyloxy; b, undecyloxy; c, dodecyloxy), have been synthesized and characterized. It was found that each of the derivatives exhibits discotic liquid crystalline properties, and that each of the Cn-Cu (4) derivatives has two kinds of Drd2(P21/a) mesophases. These Cn-Cu (4a,b,c) and C12-2H (2c) derivatives exhibit a unique double clearing behavior.
    Additional Material: 7 Ill.
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  • 93
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 661-664 
    ISSN: 0268-2605
    Keywords: third-order optical nonlinear properties ; optical susceptibility; phthalocyanine ; third-harmonic generation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Third-order nonlinear optical susceptibility, χ(3) of symmetrically octa-substituted metal-free phthalocyanine thin films measured by the third-harmonic generation technique are reported. The metal-free phthalocyanine has been found to show a χ(3) (-3ω; ω,ω, ω) value as large as 7.73×10-12 esu at 1.80 μm. The figure of merit, χ(3)/α, was estimated to be 4.17×1017 esu cm at 1.05 μm and 6.97×1016 esu cm at 1.65 μm. Both linear and third-order optical properties of liquid-crystalline metal-free phthalocyanines are discussed
    Additional Material: 2 Ill.
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  • 94
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 697-705 
    ISSN: 0268-2605
    Keywords: inorganic arsenic ; monomethylarsonic acid (MMAA) ; dimethylarsinic acid (DMAA) ; arsenic distribution ; Pacific Ocean ; Tasman Sea ; seawater ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The vertical profies of inorganic arsenic [As(III)+As(V)], monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) were investigated at four sampling stations in the Pacific Ocean and a sampling station in the southern Tasman Sea. In addition, the concentrations of those compounds in surface waters of the Pacific Ocean and Tasman Sea have been determined.The vertical profiles of inorganic arsenic showed the low concentrations in both the surface and deep/bottom zones. The depleted concentrations in the surface zone varied from 1000 to 1700 ng dm-3 and that in the deep/bottom zone varied from 1300 to 2050 ng dm-3. The maximum concentrations that varied from 1500 to 2450 ng dm-3 were usually observed at a depth of about 2000 m.Both MMAA and DMAA were observed throughout the water column at sampling stations in the north-western and equatorial regions of the Pacific Ocean. At the sampling station in the central northern Pacific gyre, DMAA was the only methylated arsenic compound observed throughout the water column. On the contrary, at the sampling station in the southern Tasman Sea, the only detected methylated arsenic compound throughout the water column was MMAA. Their vertical profiles showed maximum concentrations in the surface water which abruptly dropped with depth from 0 to 200 m. The concentration in the surface water was close to 10 ng dm-3 for MMAA and varied from 27 to 185 ng dm-3 for DMAA. At depths greater than 100 m, MMAA and DMAA were at comparable concentrations which varied from 0.7 to 14 ng dm-3.The low inorganic arsenic concentration in the surface zone was due to biological activity. This activity resulted in the uptake of As(V) and subsequent reduction and methylation to MMAA and DMAA. DMAA was the main predominant arsenic compound resulting from biological activity in surface waters.The low inorganic arsenic concentrations in the deep and bottom zones were likely to be caused by the adsorption of dissolved inorganic arsenic onto sinking particulates rich in iron and manganese oxides.
    Additional Material: 4 Ill.
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  • 95
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 721-726 
    ISSN: 0268-2605
    Keywords: arsenic ; accumulation ; Chattonella antiqua ; microalgae ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rhaphydophyceae Chattonella antiqua (Hada) Ono was grown in seawater containing an arsenic concentration up to 50 mg dm-3, and survived even at 200 mg dm-3. The arsenic content increased with an increase of the surrounding arsenic, iron and manganese concentrations. However, arsenic accumulation was unaffected by phosphorus concentration. Also, arsenic content in C. antiqua decreased at a selenium concentration of up 20 mg dm-3, and was reduced by the addition of antimony. In the living cells, about 52% of the arsenic which accumulated in each cell was found in the intracellular fraction, 27% in the lipid fraction, and 21% in the cell wall fraction.
    Additional Material: 1 Ill.
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  • 96
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 741-745 
    ISSN: 0268-2605
    Keywords: dimethylarsinic acid ; chronic exposure ; demethylation ; arsenite ; rat ; urine ; feces ; methylation ; inductively coupled plasma mass spectrometry (ICP-MS) ; ion chromatography (IC) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metabolites of dimethylarsinic acid (DMA) were studied in rats chronically exposed to DMA in drinking water. The urine was collected by forced urination at the end of 8, 20 and 30 weeks and the feces at the end of 30 weeks. The samples were analyzed for arsenic species by a combined system of ion chromatography and inductively coupled plasma mass spectrometry (IC-ICP-MS). Increases in arsenite, DMA, trimethylarsine oxide and a still-to-be-identified arsenic compound (which was eluted immediately after monomethylarsonic acid on the chromatogram) were detected in both urine and feces. At the 100 mg l-1 dose, DMA was the main component in the urine; arsenite was a main component in the feces. The results indicate that, besides undergoing methylation, DMA can be demethylated to inorganic arsenic, and demethylation of DMA may be associated with intestinal bacteria
    Additional Material: 3 Ill.
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  • 97
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 665-665 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Type of Medium: Electronic Resource
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  • 98
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 753-756 
    ISSN: 0268-2605
    Keywords: Dunaliella sp ; arsenate ; arsenite ; reduction ; water-soluble fraction ; gel filtration ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Uptake and reduction of arsenate [AS(V)] by Dunaliella sp. cells were determined to investigate the metabolic processes of arsenic in the alga. Cellular uptake of arsenic by Dunaliella sp. cells was markedly affected by the form of arsenic in the medium. The content of arsenic taken up by Dunaliella sp. cells increased rapidly with time on addition of As(V) to the medium. However, in the case of addition of arsenite [As(III)], the gradient of arsenic uptake by Dunaliella sp. cells was low, and arsenic content was small. In the water-soluble fraction of arsenic taken up by Dunaliella sp. cells with exposure to As(V), arsenic was in the forms of organic arsenic, As(V) and As(III). The content of As(V) in the water-soluble fraction increased with exposure time. The content of As(III) also increased with time, but remained constant after 5 h of exposure. On the other hand, organic arsenic content was small and did not increase with time. It was found that Dunaliella sp. takes up As(V) and readily reduces it to As(III)
    Additional Material: 3 Ill.
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  • 99
    ISSN: 0268-2605
    Keywords: organolanthanide ; alkylaluminium ; bimetallic complex ; NMR spectra ; polymerization ; single-component catalyst ; epichlorohydrin ; methyl methacrylate ; tetrahydrofuran ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three new lanthanide (Ln)-alkylaluminium (Al) bimetallic complexes with the formula [(μ-CF3CO2)2Ln(μ-CF3CHO2)AlR2 · 2THF]2 (Ln=Nd, Y, R=i-C4H9 (i-Bu); Ln=Eu, R=C2H5(Et); THF=tetrahydrofuran) were synthesized by the reaction of Ln(CF3CO2)3 (Ln=Nd, Y) with HAl (i-Bu)2 and of Eu(CF3CO2)3 with AlEt3, respectively. Their crystal structures were determined by X-ray diffraction at 233 K. [(μ-CF3CO2)2Nd (μ-CF3CHO2)Al(i-Bu)2 · 2THF]2 (Nd-Al) and [(μ-CF3CO2)2Y(μ-CF3CHO2)Al(i- Bu)2 · 2THF]2 (Y-Al) are isomorphous and crystallize in space group P1 with a=12.441(3) Å [12.347(5) Å for Y-Al], b=12.832(3) Å [12.832(4) Å], c=11.334(3) Å [11.292(8) Å], α=104.93 (2)° [104.45(4)°], β=98.47(2)° [98.81(4)°], γ=64.60(2)° [64.30(3)°], R=0.519 [0.113], Rw=0.0532 [0.110], Z=1 and [(μ-CF3CO2)2Eu(CF3 CHO2)AlEt2 · 2THF]2(Eu-Al) in space group P21/n with a=11.913(6) Å, b=14.051(9) Å, c=17.920(9) Å, α=101.88(11)°, β=γ=90°, R=0.0509, Rw=0.0471 and Z=2. The six CF3CO-2 (including CF3CHO-2) of each complex, among which pairs are equivalent, coordinated to Ln and Al in three patterns: (A) the two oxygen atoms in one of the three CF3CO-2 type coordinated to two different Ln; (B) the two oxygen atoms in the second of CF3CO-2 type coordinated to Ln and Al, respectively; (C) one of the two oxygen atoms in the third CF3CO-2 type bidentately coordinated to two Ln and another oxygen coordinated to Al and one of the two Ln, respectively. Unlike types A and B, in type C the carboxyl carbon with a hydrogen atom bonded to it was found to appear as an sp3-hybridized configuration rather than an sp2-one. 1D and 2D NMR results further confirmed the existence of such a disproportionated CF3CHO-2 ligand. Methyl methacrylate (MMA) and epichlorohydrin (ECH) could be polymerized by Y-Al or Eu-Al as a single-component catalyst and highly syndiotactic poly(MMA) was obtained. THF could also be polymerized by Y-Al in the presence of a small amount of ECH.
    Additional Material: 10 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996) 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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