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  • 1990-1994  (1,078)
  • 1980-1984
  • 1993  (1,078)
  • Inorganic Chemistry  (727)
  • Physical Chemistry  (218)
  • Industrial Chemistry and Chemical Engineering  (133)
  • Nuclear reactions
Source
Material
Years
  • 1990-1994  (1,078)
  • 1980-1984
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    A mathematical model of dehydroisomerization of methylcyclopentane using a bifunctional catalyst blend (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 191-199 
    Details
    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 of dehydroisomerization of methylcyclopentane in presence of bifunctional catalysts under industrial operating conditions is presented. The model consists of six differential equations. The rate constants are expressed as polynomial functions of the catalyst blend, and coefficients of these polynomials were determined from numerous measurements, taken along the axis of a tubular reactor. The resulting polynomial coefficients led to reaction rate constants which yielded results close to the actual process.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160308
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  • 2
    Electronic Resource
    Electronic Resource
    Extraction of zinc by alkyl thiophosphoric acids with emulsion liquid membranes (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 213-217 
    Details
    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: Treatment of a given multicomponent cationic mixture was studied applying the emulsion liquid membrane (ELM) separation technique for Zn recovery. Experimental apparatus and conditions are described. Comparative studies using two zinc-selective ion exchangers (thio-DEHPA and dithio-DEHPA) were carried out whereby the composition of the liquid membrane and the operating conditions were investigated for both extractants. A useful method of representing the concentrations of the feed and the receiving aqueous phase is proposed, which allows the occurrence of break-up and/or osmosis to be easily detected.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160311
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  • 3
    Electronic Resource
    Electronic Resource
    Electrical conductivities of pure organic liquids (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 238-242 
    Details
    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 contribution presents a method of evaluating electrical conductivities of pure organic liquids. Emphasis is placed on the methodology of selection, correlation and analysis of experimental data. The proposed method brings order out of conflicting, confusing and chaotic experimental observations. It is also shown that the consistent and evaluated data are generated at a fraction of the cost and time required for producing the original raw experimental data.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160405
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  • 4
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993) 
    Details
    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
    URL: http://dx.doi.org/10.1002/ceat.270160501
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  • 5
    Electronic Resource
    Electronic Resource
    Transient behaviour of shell and tube heat exchangersPaper presented by W. Roetzel at the “Jahrestreffen der Verfahrensingenieure”, Wein, September 30 to October 2, 1992. (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 296-302 
    Details
    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: Based on the dispersion model rather than on the conventional pluf-flow model, a method of predicting the transient behaviour of parallel and counterflow heat exchangers is developed, whereby the effects of shell-side flow maldistribution and the finite heat capacities of both fluids, tube bundle and shell are considered. The final solution has been obtained by numerical inversion of the Laplace transform, to determine the transient responses to arbitrary inlet temperature variations. The experiment was carried out in a one pass tube heat exchanger. The comparison between therotical and experimental results is presented and the feasibility of this method is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160503
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  • 6
    Electronic Resource
    Electronic Resource
    Wall factor for acceleration and terminal velocity of falling spheres at high reynolds numbers (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 314-317 
    Details
    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 wall factor for spheres in the acceleration and terminal velocity ranges was determined experimentally for very high Reynolds numbers (13 500 〈 Re 〈 70 000). Experiments were performed with 12, 15, 18, 21, 25 and 31.75 mm spheres, falling in water inside cylinders 3.4, 4.9, 7, 10, 14 and 19 cm in diameter. A published empirical equation was found to yield good results for the terminal velocity wall factor in the range of studied Reynolds numbers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160506
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  • 7
    Electronic Resource
    Electronic Resource
    A study of phase equilibria sensitivity in the 1,1,1-trichloroethane-1,2-dichloroethane separation by distillation (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 338-340 
    Details
    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 sensitivity of the plate number and reflux ratio to the description of vapour-liquid equilibria in the 1,1,1-trichloroethane-1,2-dichloroethane separation was calculated via case studies. Published experimental data are not sufficiently accurate to satisfy an adequate overdesign of the distillation column. On the other hand, the data are suitable for the design of an extractive distillation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160510
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  • 8
    Electronic Resource
    Electronic Resource
    Pellet heat transfer coefficients in packed beds: Global and local values (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 363-369 
    Details
    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: Pellet heat transfer coefficients in a packed bed have been obtained, both for specific individual pellets and for the entire bed. They are referred to as local and global values, respectively. It appears that the local values are scattered around the global value. This is due to the heat transfer coefficient of individual pellets being statistically distributed, as a result of the randomnes of the packing. At low Reynolds numbers, both global and local values fall well below Nu = 2, which is the lower limit for a single sphere in absence of convection. In the literature, this behaviour has been attributed i.a. to axial dispersion and fluid maldistribution. However, these phenomena cannot explain why the same behaviour is observed in slurries. The fact that the local values fall below Nu = 2 would suggest that neither of these explanations is valid for packed beds.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160602
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetics of tetrachloroethene photochlorination in a homogeneous system (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 429-432 
    Details
    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 mechanism of free-radical chain reaction of tetrachloroethene photochlorination in a homogeneous liquid system is discussed and three kinetic models based on the reaction mechanism are presented. The parameters of these three models have been evaluated on the basis of experimental data presented in [1].
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160612
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  • 10
    Electronic Resource
    Electronic Resource
    Comparison of single and double inert tracer fluctuation measurements in a continuous stirred tank (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 234-237 
    Details
    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 comparison is made between two different methods using laser induced fluorescence spectroscopy for measuring local concentration fluctuations in the same stirred tank. The first method using a single inert fluorescent tracer yields a segregation index quite different from that determined by the second method, which requires two inert tracers, a fluorescent one and a fluorescence quencher. By recalling the theoretical background, it is demonstrated that the characteristic segregation indices should be equal for the experiments under consideration. According to the discussion, it is likely that the double tracer method gives more reliable results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160404
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  • 11
    Electronic Resource
    Electronic Resource
    Micromixing effects on a parallel reaction in flow reactors (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 243-251 
    Details
    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: Using the micromixing concepts of Danckwerts and Zwietering, the Peclet number Pe has been correlated mathematically to the degree of segregation J for the axial dispersion model. The results were applied to compare the micromixing effects on a model, mixed-order parallel reaction system in continuous flow reactors. Axial dispersion model, and Ng and Rippin's two-environment model were used to find the micromixing effects in tubular and stirred tank reactors, respectively. The performance of these reactors, with varying geometries, has been evaluated in terms of overall conversion, selectivity, and yield under identical operating and reaction conditions. The overall conversion increases in a tubular reactor with the increase in J, irrespective of the kinetic orders. However, in a stirred tank reactor, the conversion is found to be micromixing-sensitive, depending on the order of reaction. For m = 1 and n = 2 (case 1), the conversion is fairly insensitive to micromixing effects while it decreases for m = 0.5 and n = 1 (case 2) with increasing J. For the same extent of micromixing, a tubular reactor gives, in both cases, a higher conversion than a stirred tank reactor. The selectivity, in either case, decreases in both reactors with increasing segregation effects. However, in each case, the selectivity of a tubular reactor was fairly close to that of a stirred tank reactor at the same value of J. As far as the yield is concerned, both reactors achieve nearly the same value, without significant micromixing effects.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160406
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  • 12
    Electronic Resource
    Electronic Resource
    Activity evaluation of a catalytic distillation packing for MTBE productionDedicated to Professor Dr. Horst Langemann on the occasion of his 65th birthday (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 279-289 
    Details
    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 octane enhancer methyl tertiary butyl ether (MTBE) can be produced very efficiently from methanol and isobutene in a reactive distillation column where the heterogeneous catalyst also acts as distillation packing. Some mathematical models have been published for the simulation of such a process but they focus on the physical transport processes between the vapour and liquid phases. However, the aim of this paper is to analyze the importance of the internal and external multicomponent mass and heat transfer phenomena on the catalyst under boiling conditions. Therefore, experiments were carried out in a reactive distillation column at different compositions of feed, column pressures and reflux ratios using a Raschig ring shaped acidic ion exchange resin as the catalyst. The temperature and composition of the liquid phase entering and leaving the catalytic column section were measured. These data were used to evaluate the effectiveness factor of the catalyst with a rigorous macrokinetic model. It is shown that the effectiveness factor varies significantly along the column length. Under certain operating conditions, decomposition of MTBE can occur accompanied by boiling processes inside the catalyst macropores.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160412
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  • 13
    Electronic Resource
    Electronic Resource
    Flow regimes in circulating fluidized beds (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 307-313 
    Details
    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: Based on a comprehensive hydrodynamic analysis, a practical definition of the circulating fluidized bed (CFB) regime has been proposed. It was established that two flow regimes are involved in a CFB: fast fluidization and dense phase conveying. By demonstrating the variation of pressure gradient in both the lower and the upper section of the bed versus superficial gas velocity, the criteria for the determination of transition velocities have been obtained. Literature data which over wider operating conditions, particle properties and bed diameters from the basis of the obtained generalized correlations of transition velocities. A quantitative flow diagram is presented.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160505
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  • 14
    Electronic Resource
    Electronic Resource
    Announcements (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 38-38 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100108
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  • 15
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993) 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100101
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  • 16
    Electronic Resource
    Electronic Resource
    Fractal Characterization of Pulverised Materials (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 1-6 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes preliminary work carried out on the applicability of fractal geometry in describing the products of comminution events.A nickel sulphide ore was subjected to two comminution events, impact shattering and ball milling. Fractal analysis was performed on samples of the resulting comminution products.Two differing fractal populations resulted, with the impact sample exhibiting particles having higher boundary fractal dimensions than the milled sample. The fractal dimension of the impact fragments increased with decreasing size, whereas the milled particles displayed a more complex distribution.The under-fractal distributions, of the two populations of fragments, generate straight lines when plotted on Gaussian probability paper. This leads to the possibility of being able to predict the distribution of fragments, in fractal terms, of a particular material when subjected to comminution.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100102
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  • 17
    Electronic Resource
    Electronic Resource
    Estimation of the Effective Measuring Volume of Single-Fibre Reflection Probes for solid volume concentration measurements (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 48-55 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The working principle of the single-fibre reflection (SFR) probe is that light emitted by a laser diode is guided into the measuring volume by the same fibre which receives the proportion of light reflected by the particles in the vicinity of the probe tip and transmits it back to a photosensitive element. In contrast to other configurations of fibre optical probes, the SFR probe is characterized by an unambiguous calibration graph over the entire range of solid volume concentration values. SFR probes have been successfully applied to different kinds of multiphase flow systems, e.g. fluidized beds, pneumatic conveying lines, elutriators and thickeners.A particular question for the interpretation of measurements has always been the effective size of the measuring volume, which is mainly determined by the solid volume concentration. In this paper a simplified mathematical model of the signal generation by backscattering of the emitted light at the particle surfaces is given. The theory takes into account the average optical properties of the solids and their particle size distributions.The particle properties are determined on the basis of this model, which finally delivers the shape, size and depth of the effective measuring volume. For particle sizes between 30 and 120 μm the depth of the measuring volume of a 600-μm fibre probe is between 0.2 mm for solid concentrations near the fixed-bed state and approximately 4 mm for solid volume concentrations as low as 0.1 vol.-%.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100204
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  • 18
    Electronic Resource
    Electronic Resource
    Measurement of Size, Number Concentration and Velocity of Aerosol Particles using an optical particle counter (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 56-61 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An aerosol measurement instrument is presented which allows for the simultaneous measurement of the size distribution, number concentration and velocities of particles. A commercial optical particle counter (OPC) was modified in terms of optics and signal evaluation to provide the required measurement information. The design of this instrument allows the definition of a cubic measuring volume by purely optical means. This is achieved by an aperture/lens system which projects a sharply defined light beam into a stream of aerosol flow. Light scattered from single particles at average angles of 90° is collected by two opposite receiver units, each projecting light on to a separate photomultiplier. The intensity of the scattered light with this instrument is found to be an unambiguous function of the particle size. The total number of particles detected per unit time results in the particle flux. The particle velocity can be calculated, in principle, through the correlation of the signal length and the optical length of the measuring volume, provided that the particles have a straight trajectory through the measuring volume and the measuring volume length in the mean flow direction is well defined. The absence of sharpness in real optical projections effects a border zone of definite length, in which the illumination declines to zero. This leads, together with the low-pass filtering of the particle signals, to an increase in the length of the signal slopes, causing some difficulties in the determination of the signal length. A digital signal evaluation technique was developed that renders possible the clear differentiation between the slope and the kernel region of the signal. The latter represents the motion of particles through the completely illuminated region, which can be a more accurate parameter to define the signal length. In addition to the signal length determination, a cross-correlation technique was tested for its potential to obtain particle velocity. the instrument has two interlaced measuring volumes of nearly the same size, which are shifted for this special application in the main flow direction by 20 μm. The phase difference between the signals from the two photomultipliers, together with the optical distance, yields the particle velocity.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100205
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  • 19
    Electronic Resource
    Electronic Resource
    In-Line Particle Size Determination for Jet Agglomeration Processes (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 74-78 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In jet agglomeration plants, powders are agglomerated to obtain good instant properties. The free-falling initial material is wetted in a spray cone by droplets or in a steam jet by condensation at the particle surface. In a subsequent region of high particle concentration, collision between particles occurs and agglomerates form, if the forces of adhesion are strong enough. A commercial measurement device, working according to the principle of Fraunhofer diffraction, was modified for in-line application. It was used to measure particle size distributions and concentrations of solid particles and droplets in jets. A model is presented to calculate local particle sizes by means of mass balances from integral measurements over large volumes. The results of in-line particle size and agglomerate size analyses show the practical importance of dry agglomeration during transport and lead to a better understanding of the subsequent wet agglomeration process.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100208
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  • 20
    Electronic Resource
    Electronic Resource
    Announcements (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 92-94 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100211
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  • 21
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993) 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100301
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  • 22
    Electronic Resource
    Electronic Resource
    Particle Dispersion in Highly Swirling, Turbulent FlowsDedicated to Professor Friedrich Löffler on the occasion of his 60th birthday (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 182-190 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Three-dimensional transport processes of monosized droplets in a turbulent swirling shear layer were investigated experimentally and theoretically. A model experiment was designed that represents the spray dispersion produced by airblast atomizers. Based on the experimental results, a stochastic dispersion model was developed in the frame of a Lagrangian formulation. Comparison with these experimental data for the dispersion of monosized droplets were made and proved to be satisfactory. The analysis of the remaining differences between calculation and measurement emphasized the importance of an accurate description of gas-phase turbulence characteristics.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100406
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  • 23
    Electronic Resource
    Electronic Resource
    Comparison of Dry Test Sieving on Woven Wire Cloths versus electroformed sheetsDedicated to Professor Friedrich Löffler on the occasion of his 60th birthday (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 222-225 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dry test sieving results given by woven wire cloths with a square mesh and by round electroformed apertures were compared using sands of various origin. The difference has been found to be constant and independent of substance and quantile. The quantile obtained on a square mesh was converted into the corresponding quantile on an electroformed sheet of the same nominal aperture by multiplication by a constant factor of 1.21 ± 0.04.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100410
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  • 24
    Electronic Resource
    Electronic Resource
    Dense Monolayers of Monodisperse Opaque Spheres: Transmission and diffraction in the fraunhofer domainDedicated to Professor Friedrich Löffler on the occasion of his 60th birthday (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 201-211 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The transmission and diffraction of radiation through dense monolayers of monodisperse opaque spheres were studied for the Fraunhofer domain. Theoretical considerations, numerical calculations and experiments on ultrasonic transmission and on laser light transmission and diffraction yielded corresponding results. Complementary studies included the cases of sterically non-interacting particles (by numerical simulation) and of small particle size parameters (by ultrasonic extinction). Transmission was found to be, in general, a non-linear function of the monolayer density. Secondary effects on the transmission can be attributed to the effect of the monolayer structure (characterized by the pair correlation function) on the angular distribution of diffracted intensity. The results were found to be in accordance with experimental results on extinction in three-dimensional systems.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100408
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    Electronic Resource
    Editorial (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 228-228 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100502
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  • 26
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    Fractal Differentiation Between Wear and Contaminant Particles found in mining machinery lubrication systems (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 308-312 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes preliminary work carried out on the applicability of fractal geometry for differentiating between wear and contaminant particles found in mining machinery lubrication systems.Coal dust, stone dust and roadstone dust from a granite quarry were used as the contaminant particles and the particles from two crushers, which had failed whilst in service, were used to provide the wear particles.Two differing populations appeared with the wear particles having higher boundary fractals than the contaminant, but tending to spread across a wide range of fractal numbers, whereas the contaminants were lower and fairly tightly grouped.The underfractal distributions of the two populations of particles, generate straight lines when plotted on Gaussian probability paper. This leads to the probability of being able to predict the distribution of particles, in fractal terms between wear and contaminant particles.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100604
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  • 27
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    Measurement of Aggregate Fractal Dimensions Using Static Light Scattering (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 239-245 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aggregates formed from colloidal particles will vary in shape according to the aggregation regime prevalent. Compact structures are formed when the aggregation is slow, whilst loose tenuous structures are formed when rapid (or diffusion limited) aggregation prevails. These structures can be fractal in nature, that is, there is a relationship between porosity and the number of primary particles making up the aggregate, and is described by the fractal dimension, dF. Fractal dimensions of hematite aggregates have been measured experimentally using the static light scattering technique. Fractal dimensions varied with aggregation regimes; for the rapid aggregation regime, dF was found to be 2.8, whilst for conditions in which aggregation was slow (retardation forces prevail), dF's of 2.3 were measured. For conditions which lead to aggregation in which both diffusion and retardation forces play a part, structures with fractal dimensions such that 2.3 〈 dF 〈 2.8 were found.The effects of adsorbed fulvic acid, a naturally occuring organic acid, on the kinetics of hematite aggregation and on the resulting structure of hematite aggregates were also investigated. The study of aggregate structure shows that the fractal dimensions of hematite aggregates which are partially coated with fulvic acid molecules are higher than those obtained with no adsorbed fulvic acid. The scattering exponents obtained from static light scattering experiments of these aggregates range from 2.83 ± 0.08 to 3.42 ± 0.1. The scattering exponents of greater than 3 indicate that the scattering is the result of objects that contains pores which are bounded by surfaces with a fractal structure, and can be related only to surface fractal dimension. The high fractal dimensions are due to restructuring within the aggregates, which only occured at low coverage by the organic acid.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100505
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  • 28
    Electronic Resource
    Electronic Resource
    Editorial (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 300-300 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100602
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  • 29
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    Determination of the Fractal Dimension of the Irregular, Compressive Stress-Strain Relationships of brittle, crumbly particulates (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 301-307 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The apparent fractal dimension of normalized rugged compressive force-deformation curves of two types of brittle particulates was determined using the blanket algorithm. Although the shape of the original force-deformation relationships of the individual specimens was irreproducible, the apparent fractal dimension of the normalized data was fairly constant and characteristic of the material. The applicability of the algorithm and the validity of the results were tested with computer simulated relationships generated with a set of Weierstrass functions whose fractal dimension was known a-priori. It is demonstrated that as long as the resolution along the two axes is the same, the fractal dimension so calculated provides an absolute rather than a relative measure of the relationship's jaggedness.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100603
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  • 30
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    Particle Trajectory Effects in Phase Doppler Systems: Computations and experiments (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 332-338 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of the particle trajectories on phase Doppler measurements were explored numerically using generalized Lorenz-Mie theory. Computations were performed for a commercial phase Doppler system and various schemes for elimination of the trajectory effects were examined. It is shown that these effects cannot be completely suppressed if the ratio of the two measured phase shifts from a single receiving unit is used to validate the measurements. On the other hand, the errors due to particle trajectories can be eliminated satisfactorily by employing an additional receiving unit, which allows one to detect the asymmetry of the scattered light pattern due to displacement of the particle trajectory from the centre of the measuring volume. A preliminary experimental evaluation of this method is presented and discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100607
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  • 31
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993) 
    Details
    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
    URL: http://dx.doi.org/10.1002/ceat.270160101
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  • 32
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    Increased surface tension of pretreated plastics investigated with a fully automatic device (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 24-25 
    Details
    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: Measurements of surface tension of flame-, plasma- and UV-treated PP-EPDM samples show that all three methods of pretreatment significantly increase the surface tension. The flame or plasma pretreatment increases especially the polar element of surface tension while the UV-treatment enhances the disperse element. The measurements were carried out with a new fully automatic unit for determining contact angles (AURAM).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160105
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  • 33
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    Binary ion exchange equilibrium for Ca2+, Mg2+, K+, Na+ and H+ ions on amberlite IR-120 (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 35-39 
    Details
    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: Experimental data are reported for ion exchange equilibria of binary systems on Amberlite IR-120 resin, at different temperatures and total ionic concentrations in aqueous solutions. These systems exhibit non-ideal behaviour in both phases, and the equilibrium characterization has been based on the law of mass action, using Wilson and Meisssner, and Kusik equations to correlate the activity coefficients in the resin and aqueous solutions, respectively. Equilibrium constants, standard thermodynamic properties (Gibbs free enthalpy changes, enthalpy and entropy) and Wilson binary parameters were obtained as functions of temperature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160107
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  • 34
    Electronic Resource
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    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993) 
    Details
    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
    URL: http://dx.doi.org/10.1002/ceat.270160201
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  • 35
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    Kinetics and mechanism of oxidative coupling of methane over sodium-manganese oxide catalyst (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 62-67 
    Details
    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 kinetics of methane oxidative coupling (OCM) was studied using 1 g of Na-Mn2O3 catalyst at 1073 to 1123 K, in an integral flow reactor (I.d. = 10 mm), at atmospheric pressure with methane and oxygen partial pressures of 0.27 and 0.13 bar, respectively, so that the ratio of CH4 to O2 was 2. The flow rate range was 50 to 200 ml/min. the kinetic data were analyzed by the Rideal-redox type of rate equation assuming the methyl radical and active surface oxygen to be the steady-state intermediates. Oxidation and reduction rate constants (Kox, Kred) for methane consumption were calculated from experimental catalysis results by computer simulation using the multiple least squares method. The activation energies at rate constants Kox and Kred for this type of catalyst were reported as 43.26 and 62.2 kcal/mol, respectively.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270160111
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  • 36
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    Temperature oscillation technique for determination of local convective heat transfer coefficients without fluid temperature measurementPaper presented at the “Jahrestreffen der Verfahrensingenieure”, Cologne, September 25 to 27, 1991. (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 89-93 
    Details
    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 experimental technique with periodic laser heating is described and applied to the measurement of local heat transfer coefficients at the inner surface of an agitated vessel. Only radiative surface temperature measurements on the outer wall of the vessel are necessary.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160204
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  • 37
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    Techno-Economic investigation of an air humidification-dehumidification desalination process (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 270-274 
    Details
    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 a humidification-dehumidification (H.D.) process suitable for desalination of sea- and brackish water. The work correlates performance characteristics of the combination of different components in such a loop. Water yield, energy requirement and design data are evaluated as functions of different parameters. The investigation covered water to air mass ratios ranging from 60 to 80, concentration ratios between 2 and 5, at a temperature difference of between 10 and 16 °C, along the liquid for dehumidification. The results showed that 76% of energy consumed in the humidifier is recovered by condensation. Increase of the concentration ratio to 5 can reduce the make-up water and rejected brine by about 58% and 24% respectively. Cost calculations show that the H.D. process has significant potential as an alternative for small capacity desalination plants and permits to operate systems as small as 10 m3/day in output.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160410
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  • 38
    Electronic Resource
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    Gas and solids mixing in a commercial FCC regenerator (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 109-113 
    Details
    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: Mixing of gas, solids and heat in a commercial FCC regenerator, 5.76 m in diameter, was investigated. This regenerator was operated at a high superficial gas velocity (〉1.2 m/s) and high temperature (650-710°C). It is classified as a highly efficient regenerator. The profiles of coke content in the catalyst, gas composition, temperature and pressure were obtained by sampling and instrumental measurement. It was confirmed that a proposed axial dispersion model could be used for a satisfactory prediction of these experimental profiles. The values of gas and solids dispersion coefficients are also presented.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160207
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  • 39
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    Industrial fires and explosions due to electrostatic ignition (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 325-331 
    Details
    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: Static electricity is a frequent source of fires and explosions in industry. A variety of operations may generate static electricity leading to such fires and explosions. This requires adequate preventive and protective measures against this hazard. The present paper describes the theory and mechanism of electrostatic sparking, parameters needed to assess the respective hazard in a plant, safety measures to combat electrostatic problems, common operations where such problems exist and measures to eliminate or mitigate these problems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160508
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  • 40
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    Determination of operating characteristics of agitators in tubes (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 172-179 
    Details
    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: Operating characteristics of an agitator in a tube are necessary for the calculation of its pumping capacity and power consumption in a given configuration. General dimensionless equations for pumping and power characteristics are presented which were derived by inspection analysis of basic equations. Experimental procedure for the determination of these characteristics is put forward. This procedure is based on the measurement of flow rate or pressure rise and power consumption for an agitator in a draft tube, calandria or closed tube. The measurements and their evaluation are illustrated on the example of a three-blade screw agitator.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160305
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  • 41
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    Standardization of a newly designed vibrating capillary apparatus for the preparation of microcapsules (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 395-398 
    Details
    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: Vibrating capillary apparatus (VCA) was designed and constructed for the preparation of sulphamethoxazole (SMZ) microcapsules using gelatin as a coating polymer. The microcapsules were characterized by physico-chemical methods. The apparent diffusion coefficient Da and diffusion rate constant KBL of the drug were measured at pH of 1.2 and 7.2. Better controlled release products were obtained in the VCA.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160607
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  • 42
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    Conversion of ethanol over metal-exchanged zeolites (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 332-337 
    Details
    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 effects of metal exchange between zeolites and alkali metals (Li, Na, K; zeolite Y, ZSM-5, T), alkaline earths (Mg, Ca, Sr, Ba; ZSM-5), transition metals (La, Ce, Cr, Mn, Fe, Co, Ni, Pd, Cu, Zn; ZSM-5) and aluminium (ZSM-5) on the conversion of ethanol were studied. Activities of the catalysts and selectivities for ethene, C3+ olefins, paraffins and arenes strongly depended on the cation, chosen for the modification. Only ethene was formed by alkali exchanged zeolites, the most active being Li-Y. This could be confirmed by a long-term ageing test with Li-Y pellets under semi-industrial conditions. The exchange of ZSM-5 with alkaline earths or transition metals permitted the formation of a wide variety of products, raning from high ethene to high aromatic yields. A correlation between certain product selectivities and electronegativity was only possible in a rough approximation.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270160509
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  • 43
    Electronic Resource
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    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993) 
    Details
    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
    URL: http://dx.doi.org/10.1002/ceat.270160601
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  • 44
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    Investigations on hydrodynamics of radial flow moving bed reactorsThis paper was presented at ACHEMASIA'92, International Meeting on Chemical Engineering and Biotechnology, Beijing, PR China, May 1992. (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 383-388 
    Details
    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: Distributions of pressure and velocity in the main channels were studied in a radial flow cold model of a moving bed reactor, 500 mm in diameter, in four different gas flow modes, inward Z gas flow, inward Π gas flow, outward Z gas flow, outward Π gas flow. It has been found that, in outward Π gas flow mode, the axial non-uniformity of the gas is at a minimum. The following correlations are proposed for the momentum recovery factors Ka and Kb: Ka = 0.684 + 0.0128 (du/dx)/u, Kb = 1.135 + 0.0158 (du/dx)/u. Pressure distributions in the main channels can be accurately predicted using Ka and Kb.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160605
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  • 45
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    Comparison of selected methods for downstream processing in the production of bacterial lipase (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 405-412 
    Details
    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: Enzymes are of growing interest to the chemical and pharmaceutical industries as highly specific biocatalysts. An obstacle to a large-scale application of such proteins is the expenditure on recovery operations which can amount up to 80% of the total production costs. Therefore, it is necessary to investigate in detail the individual stages of downstream processing in order to obtain high product yields without loss of quality. After a survey of recovery operations and information on some special features of proteins which are relevant to downstream processing, this paper deals with the methods of precipitation, chromatography and foam fractionation. Several results obtained with a real, multicomponent system, namely the supernatant of lipase fermentation, are presented and compared with one another.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270160609
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  • 46
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    Comparison of cracking and hydrocraking of n-heptane on H-ZSM-5 catalystsDedicated to Professor Emeritus Dr. Hanns Hofmann on the occasion of his 70th birthday (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 422-428 
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    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: Acid catalyzed cracking and bifunctional cracking of n-heptane were investigated on HZSM-5 catalysts. At a reaction temperature of 543 K, the cracking on metal-free zeolite was found to be directly proportional to hydrogen partial pressure. Hydrogen influences the hydrogenation of product olefins and carbon deposits and therefore enhances the overall activity. Under the same conditions, in the presence of platinum, the hydrocracking rate reaches a maximum with increasing hydrogen partial pressure. The reaction can be formally described by a Langmuir Hinshewood mechanism: hydrogen is adsorbed on Pt in competition with hydrocarbons. The maximum reaction rate depends on a favourable ratio of the two adsorbed reactants. The energy of activation of hydrocracking was over 100 kJ/mol higher than that of acid cracking.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270160611
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  • 47
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    Optimization and adaptive control of a semi-batch synthesis reactorPaper presented by J. Uhlemann at the “Jahrestreffen der Verfahrens-Ingenieure”, Köln, September 25 to 27, 1991. (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 17-23 
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    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 optimization of a chemical synthesis aims at an adjustment of the operating conditions, i.e. pH, temperature and initial concentrations, in order to obtain maximum yield, minimum operating costs or similar. The optimization effort may be considerable so that, in many cases, its cost cannot be justified, especially for small volume products. This paper introduces a new strategy, namely to establish the optimum operating conditions with a relatively small effort. The new approach is illustrated by the synthesis of 2-furyl oxirane. In the first step, a simplified mechanistic process model has to be determined on the basis of easily accessible experimental data. Initial and final concentrations of all reacting components, reaction time and temperature must be known. A two-step evaluation yields the stoichiometric coefficients of all the occurring reactions as well as the parameters of the Arrhenius model. This so-called trend model is used in the optimization of the operating conditions. It is not only important to know the optimum operating conditions but also to maintain them as close as possible in practical operation. An adaptive controller is well suited to such an application and its use is discussed.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270160104
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  • 48
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    Mass transfer in packed columns: The cylinder model (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 46-57 
    Details
    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 order to predict mass transfer in packed columns, it is necessary to know the interfacial area. The well-known and often cited equation (Onda, Kolev, Zech, etc.) do not yield precise values for the mass transfer coefficient βL ae or the interfacial area ae, especially for modern packing elements. A new model will be presented which takes into account the structure of packing (cylinder model) as well as the structure of the liquid hold-up. This model allows the separation of liquid flow through packings into its main constituents, i.e. rivulets and drops (freely falling). The determination of the structure of liquid flow allows the prediction of effective interfacial areas as well as of volumetric mass transfer coefficients for irrigated large packing elements manufactured from plastics, metals or ceramic. The applicability to novel future packings is one of the advantages of the new model.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160109
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    Liquid phase oxidation of α-pinene initiated by ozone. 1. Conversion of α-pinene and formation of its hydroperoxide (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 68-74 
    Details
    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 use of ozone as initiating agent in the liquid phase oxidation of α-pinene has been investigated. The first intermediate product of the reaction is the hydroperoxide of α-pinene. Both, ozone partial pressure and its initiation time exert an inhibiting effect on the conversion of α-pinene but yield higher selectivities for the hydroperoxide of α-pinene compared with those of oxidation without ozone. In all cases, temperature was found to be the most important variable affecting the oxidation rate. From a mechanism of radical reactions, kinetic equations, consistent with the experimental results, corresponding to α-pinene oxidation rate and net formation rate of its hydroperoxide, were obtained. The rate constants are given as functions of temperature. The results also suggest that a fraction of the hydroperoxy radicals decomposes to yield other products such as verbenol and verbenone, identified in this work, and whose kinetics will be reported in a later paper.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160112
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  • 50
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    A general method of designing gas and gas-liquid injectors using laws of turbulent jet mixingPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Cologne, 25-27 Sept. 1991. (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 94-101 
    Details
    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: Based on the equation for entrainment of a turbulent free jet, a simple method of designing gas and gas-liquid injectors is presented. Using the formula for mass flow ratio of an injector consisting of a nozzle and a short cylindrical mixing tube open at both ends, a general equation for designing any injector with variable geometry and flow resistances is given. The optimization procedure is outlined. Compared to the conventional design of injectors, starting from macroscopic mass and momentum balances, the present method is much simpler, easily applicable and involves only one empirical entrainment coefficient. It is particularly advantageous in the case of variable density of the motive and entrained fluids since the density ratio appears explicitly in the relevant equations.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160205
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  • 51
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    Bed collapse technique for estimating parameters of generalized wake model for a three-phase fluidized bed (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 119-124 
    Details
    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 hydrodynamic behaviour of a cocurrent gas-liquid-solid fluidized bed was studied by using the bed collapse technique. The key parameters, k and x, of the generalized wake model were estimated. Compared with other existing methods for evaluating the parameters k and x, the bed collapse technique shows some distinct advantages. Parameters are derived directly from experiments in a three-dimensional three-phase fluidized bed and there is no need to assume that a bubble and its wake form a perfect sphere. Hold-up data of the three-phase fluidized bed predicted by the generalized wake model with k and x estimated by the bed collapse technique are in good agreement with those obtained via the traditional pressure-drop method.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160209
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  • 52
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    Influence of solids concentration and static mixers on fluid dynamics in three-phase fluidized bed bioreactors (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 147-152 
    Details
    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 influence of solids concentration and static mixers on the hydrodynamics of the gas phase was studied for a three-phase fluidized bed bioreactor (air, nutrient solution, biocatalyst Ca alginate beads). Axial gas hold-up profiles, radial gas velocity profiles, mean bubble diameter and gas/liquid interfacial area per unit volume were measured in a bubble column (DR = 0.142 m, HR = 1.748 m). The influence of solids concentration on the gas hold-up is insignificant; static mixers enhance the gas hold-up in the reactor volume element in which they are installed. Axial gas velocity decreases with increasing solids concentration. At high solids concentrations, static mixers exert little influence on the gas phase but, at low concentrations, they do. A model is suggested to describe the influence of solids concentration (characterized by turbulent viscosity vt) and static mixers (characterized by profile parameter n) on the gas velocity profile.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160302
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  • 53
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    Kinetics of coal desulphurization by Acidianus brierleyi (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 180-185 
    Details
    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: Acidianus brierleyi was demonstrated to remove pyritic sulphur from coal. A. brierleyi was also found capable of catalyzing the removal of what is normally reported as organic sulphur from coal 171US34. A kinetic analysis was performed by assuming a first order reaction. The first order kinetics allowed a comparison with literature data for Thiobacillus ferrooxidans. Also, formation of jarosite was taken into account in the analysis. The simple first order kinetics was observed to fit the data on removal of sulphur satisfactorily.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160306
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  • 54
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    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993) 
    Details
    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
    URL: http://dx.doi.org/10.1002/ceat.270160401
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  • 55
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    Liquid homogenization in agitated tanks (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 229-233 
    Details
    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 presents a very simple model of liquid homogenization in a mixing tank. The model, based on the pumping capacity of impellers and the degree of homogeneity, is valid for turbulent mixing; however, it has been extended to transient regime of mixing (Re = 100 to 1000).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160403
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  • 56
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    Measurement of gas hold-up in three-phase systems by ultrasonic technique (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 260-262 
    Details
    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: It was established by using double impulse method that the transmission time of an ultrasonic wave, which passes near a bubble, is either shorter or longer than that in the liquid system. This is attributed to the fluid vortex originated by the bubble rising ahead of the wave. The longitudinal distribution of gas hold-up in a three-phase system, measured by analyzing wave shape and reduction of transmission time is in good agreement with that obtained by using the static pressure method. This indicates the possibility of application of ultrasonic techniques to the simultaneous measurement of phase hold-ups in the three-phase system.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160408
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  • 57
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    Drying characteristics of starch in an inert medium fluidized bed (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 263-269 
    Details
    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 effects of gas velocity (0.32 to 0.67 m/s), inlet gas temperature (25 to 100 °C) and the mass ratio of starch to inert particles (0.1 to 0.4) on the drying rate of starch in a 0.083 m-ID × 0.80 m-high inert medium fluidized bed were investigated. The drying mechanism in an inert medium fluidized bed can be classified into adhesion-dispersion, evaporation and disintegration steps. The drying rate increases with the increasing inlet gas temperature and velocity; the rates being about 10 times those reported for an agitated pan dryer. However, the drying rate decreases slightly as the mass ratio of starch to inert particles increases. Also, the drying rate exhibits a maximum at an optimum bed porosity. The drying rate data obtained in an inert medium fluidized bed have been correlated with the relevant dimensionless groups, i.e. Stefan and particle Reynolds numbers based on the theory of isotropic turbulence.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160409
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    Cooling water treatment by ozonization (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 275-278 
    Details
    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: Ozonization of water in a cooling tower was investigated. A laboratory experimental set-up was employed to study changes in water quality during ozonization. Measured data were analyzed in the context of cooling water's resistance to corrosion, scaling and biofouling. A method is proposed for determining the suitable dosage of ozone for maintaining the necessary water quality. It has been found that ozonization is very effective in maintaining the correct water quality for the required purpose and provides an attractive alternative to the conventional multiple chemical method of cooling water treatment.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160411
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    Fuzzy sets. Introduction to theory and applications in process engineering (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 291-295 
    Details
    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: Fuzziness is quite a different notion from probability. Probability describes the objective uncertainty obtained on the basis of a large number of observations. Fuzziness describes the uncertainity that has a subjective meaning. Fuzzy notions describe the degrees of possession of a given property. The popularity of fuzzy set theory in solving control problems results from its ability to treat some situations which are difficult to deal with by the classical control theory. Fuzzy sets are used to control ill-defined, complex, non-linear systems. There are two aspects of this phenomenon. The first aspect concerns the descriptive ability of fuzzy sets. The second important feature is the applicability of fuzzy sets to work with incomplete, contradictory and subjective information. Fuzzy set theory is becoming increasingly important tool in the new fast developing disciplines of artificial intelligence: expert systems and neural networks. It creates completely new opportunities for the application of fuzzy sets in chemical engineering.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160502
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    Studies on parametric sensitivity and safe operation criteria of batch processes (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 318-324 
    Details
    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 accumulation in batch reactors may eventually lead to a temperature runaway. Critical values of process parameters were used to investigate process safety. Parameter sensitivity is discussed for a wide range of operating conditions. Two criteria for safe operation are presented, based on critical values of process parameters.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160507
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    Defect structure of metal oxides at high temperatures (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 341-346 
    Details
    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: High temperature oxidation of some metals contained in special alloys has been studied. Defect models for pure an doped CoO and pure NiO were developed and fitted to electrical conductivity data. The models involve different kinds of theoretically possible complex defects with different numbers of vacancies and interstitials forming a cluster. Equilibrium constants for defects formation have been estimated using an algorithm based on the constrained variation method that allows fitting of data to implicit models involving errors in all the measured variables. Results indicate the presence of a significant concentration of complex defects in CoO at high temperatures, while confirming the rather small concentration of these defects in NiO.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160511
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  • 62
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    A physical model for the prediction of liquid hold-up in two-phase countercurrent columns (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 370-375 
    Details
    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 contribution presents the determination of liquid hold-up in gas/liquid two-phase countercurrent columns filled with random or structured packings. The equations resulting from the established physical relationships are varified against the values for liquid hold-up determined experimentally on 56 different column packings and 16 gas/liquid systems. The experimental and calculated results agree well, with only slight deviations. This also applies to the range between the loading and flooding points for two-phase countercurrent flow.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160603
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    Correlation and prediction of gas solubility in heavy complex liquids (1993)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 399-404 
    Details
    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 lattice-gas model is used for calculating the solubilities of light gases in heavy complex hydrocarbons. For waxes, the model gives a good prediction of the solubilities on using the molecular weight of the liquid to describe the solvent. For crude oils and coal-derived liquids, the prediction is of only modest quality. However, it does improve on using experimental Henry's constants.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270160608
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  • 64
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    The Angular Polarization Ratio for the Characterization of Small Droplets in Oil Sprays (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 19-25 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The angular patterns of the polarization ratio were calculated for droplets with diameters between 0.020 and 50 μm at 500 nm wavelength. It was observed that the patterns for droplets slightly smaller than 1 μm were dominated by a backward peak belonging to the glory. The peak was successfully used to characterize aerosols of light and heavy oils with a Junge-like size distribution. Experiments conducted with heavy oil sprays produced by air-assisted atomization presented the same feature. A quantitative comparison of the experimental results with the Lorenz-Mie theory showed that the size distribution of these sprays was bimodal.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100105
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    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993) 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100201
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    Scattered Light Photometer for On-Line monitoring of size distribution parameters and particle number concentration (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 33-37 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A scattered light photometer which monitors the particle number concentration of aerosols is described. The photometer measures the scattered light from illuminated submicron particle clouds with known material properties at certain scattering angles. Intensity ratios in combination with the degree of polarization are used to determine the mean particle diameter and the geometric standard deviation of an assumed log-normal particle size distribution. The determination of the particle size distribution is based on an algorithm which compares the measured and calculated (Mie theory) relative intensity quantities described. Furthermore, the particle number concentration is monitored from a single absolute intensity measurement at one scattering angle. In order to obtain quantitative results a spherical particle shape is required.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100107
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    Particle Dynamics in an Electrohydrodynamic Flow Field investigated with a two-component laser-doppler velocimeter (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 41-47 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A laser-Doppler instrument has been used to measure the migration velocity of NaCl particles in an electrohydrodynamic flow field of an electrical precipitator. The measured average migration velocity of 1.40-μm particles (number distribution median with a geometric standard devitation of 1.46) is approximately five to six times higher than the calculated steady-state velocity for a 1.40-μm particle, provided there is a saturation charge of at least 90f%. Further, the particle velocities in the main flow direction are also influenced by the electrical operation conditions. Both observations demonstrate the important role of the state of the electrohydrodynamic flow field (superposition of moving gas ions and neutral gas molecules) on the particle transport, characterized by the dimensionless electrohydrodynamic number NEHD. A comparison between six different electrohydrodynamic states revealed that NEHD ≍ 1 is a critical value for the mutual interactions between the gas ions and the neutral gas phase. Whereas for NEHD values 〉 1 the stochastic particle motion is chiefly determined by the nonsteady-state character of the negative corona, for NEHD values 〈 1 the particle velocity fluctuations are governed by the turbulence level of the neutral fluid. These finding might be helpful in adjusting the operating conditions in electrical precipitators for and optimized particle separation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100203
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    Sampling of Autocorrelating Powder Flows (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 70-73 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sampling powder flows in industrial grinding circuits are discussed. Work was done with different types of sampler and with different minerals and sampling objectives. It was found that all the samplers showed marked autocorrelation in sample mass for all the minerals ground. Typical autocorrelation could be found at both high (1 · 10-3-15 · 10-3 Hz) and low (1 · 10-4 - 4 · 10-4 Hz) frequencies. Higher frequencies were attributed to powder transport and low frequencies to mill circuit variations. The effects of the found autocorrelation on systematic errors and on industrial sampling schemes are discussed. Systematic sampling produced large errors if operated at sampling intervals that were high-frequency autocorrelation frequencies or small multiples of these. Low-frequency autocorrelation was less detrimental to the sampling results.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100207
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  • 69
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    The Relevance of Particle Measurement Technology to Process Engineering (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 86-91 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To produce disperse products, the characterization of the disperse state and a knowledge of the property function are essential. Property functions are applied not only to characterize the quality of an end product, but also to determine the influence of different processing steps on its state. Hence it is necessary to know the property and process functions for quality assurance of the products and for safety of the processes.Good laboratory particle measuring technologies are available for investigating property and process functions. On the basis of these functions, process control takes place. On-line or, better, in-line measuring techniques are necessary to enable the accompanying process information to be obtained.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100210
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    Flow Characteristics of Granular Bulk Materials (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 79-85 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The paper discusses the interest in conventional triaxial tests widely used in soil mechanics for a better understanding of both the mechanical behaviour and flow characteristics of granular bulk materials. It proposes a rheological characterization of granular foodstuffs on diverse types of stress path using a conventional triaxial cell. The characteristic state concept, defining the disaggregation threshold of the granular structure, is found to be suitable and even indispensible for examining the mechanical behaviour and the flowability of stored bulk materials. The experimental results readily suggest, as an indicator of the arching effect, a rheological index that characterizes the particle interlocking breakdown and hence the flowability of the stored materials. In addition, this study offers a realistic physical meaning for parameters in use in constitutive models (yield conditions and flow rules) when describing granular flow in various hopper geometries. The case of silos equipped with vibrating hoppers necessitates additionally the study of the rheological behaviour of materials under cyclic and vibratory loadings in order to analyse the processes of densification or disaggregation conditioning the flowability of the stored materials during emptying operations.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100209
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    Light Scattering by Anthophyllite-Crocidolite Asbestos Fibers. Part I: The domain of convergence of the EBCM theory (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 111-117 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Extended Boundary Condition Method (EBCM), also known as the T-matrix method, is used to compute exactly the scattered intensities from homogeneous isotropic circular cylinders characterized by relative refractive index N, diameter D and length L. The domain of convergence of the method regarding the parameters N, D, L is established. The effect of the geometry of the fiber ends on the scattered intensities is considered. The incident field is assumed to be a linearly polarized plane harmonic wave.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100303
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    The Characterisation of Particles Using the Settling Rate dependent movement in two phase flowsRevised version of a paper presented at the 25th Anniversary Conference “Particle Size Analysis”, Loughborough, University of Technology, 17th-19th September 1991.Dedicated to Professor Friedrich Löffler on the occasion of his 60th birthday (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 159-166 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The drawback of conventional sedimentation methods, mainly their extremely long sedimentation time for small particles, can be overcome in two phase flow systems. In this paper several principles which permit the rapid determination of settling rate distributions are discussed. Settling rate distributions can be determined from the accelerated particle movement in a flow of constant velocity at low and high solids concentrations. Another system uses accelerated flow at low solids concentrations. The best utilisation of settling rate applications have socalled cross flow systems as set up in a stagnation point flow, in a flow round a bend, or in the decelerated particle movement perpendicular to a flow of constant velocity.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100403
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    Cessation of Aggregate Growth (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 152-155 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various methods are available for reducing or ceasing growth of aggregating suspensions including the addition of highly charged adsorbents (such as gelatin), reduction of ionic strength by dilution, increase in surface charge by alteration in pH and reduction in suspension temperature. The effectiveness of each of these methods in stopping the aggregation of colloidalhematite without altering the aggregate size distribution is examined in this study. Reduction in aggregate temperature is found to be a particularly effective way of stopping the aggregation of hematite while preserving size distribution information.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100308
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    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993) 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100401
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    Description of Two-dimensional Distributions of Particle Size and Particle Velocity of a flowing discontinuous phase by means of special mathematical functionsDedicated to Professor Friedrich Löffler on the occasion of his 60th birthday (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 167-172 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As potential approximation functions for measured two-dimensional distributions, the two-dimensional normal distribution and the two-dimensional log-normal distribution are presented, in addition to mixed forms in which one of the two variables is linearly and the other logarithmically normally distributed. For all four distribution functions, regression curves are calculated, with x being understood as independent and y as dependent variable. The general concept is applied to the specific case of a two-dimensional distribution of particle size x and particle velocity y. In this context, a number of particularities result from the fact that a distinction has to be made between concentration-dependent and flux-dependent measurement.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100404
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    Particle Mass Loading Effect on a Two-Phase Turbulent Downward Jet FlowDedicated to Professor Friedrich Löffler on the occasion of his 60th birthday (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 173-181 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The particle mass loading effect on the flow structure of a two-phase turbulent jet flow was studied. A particle mass loading ratio ranging from 0 to 3.6 was used as the control parameter. The polystyrene solid particles used had nominal diameters of 210 and 780 μm. The flow Reynolds number, which was based on the pipe nozzle diameter and the fluid-phase centerline mean velocity, was 2 × 104 in the current test. A two-color laser Doppler anemometer (LDA), combined with the amplitude discrimination method and the velocity filter method, was employed to measure the mean velocity distributions for the particle and fluid phases, and the turbulent intensities and Reynolds stresses of the flow. The two-phase jet flow field was measured from the initial pipe exit to 90 D downstream. Another one-component He—Ne laser LDA system was also applied to obtain the energy spectra and temporal correlations of the two-phase jet flow.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100405
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  • 77
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    Neural Networks for Flow Regime Identification with dry particulate flow (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 234-238 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This work on imaging of particulate processes using electrical charge tomography uses two basic techniques: the multi-sensing of electrical charge in a cross-section of the flow pipe and a neural network based flow regime identification system to aid in the image reconstruction process.A measurement system, consisting of sixteen sensors, placed at equal distance from each other around the boundary of a circular 100 mm bore pipe, is used to determine the voltage profile of the flow for several artificially produced flow regimes: full, annular, core, half and stratified. A sand flow system is used to produce these different flow regimes, which are created artificially by using baffles of different shapes that obstruct the sand flow.The voltage profile from the sixteen sensors gives spatial information of the flow regime. These profiles are normalised and formed into patterns that are presented to a Kohonen neural network for classification. Two regime classification between clearly distinct regimes gives an accuracy of identification of 85%. Classification of closely similar patterns show much less accuracy of 30%.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100504
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    In-Process Particle Size Distribution Measurements and Control (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 262-265 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In-process measurement of particle size and concentration distributions provides continuous analysis and quality control of a product stream. Elimination of sample handling and operator manipulation is now possible for most pneumatic flows using optical methods which are properly interfaced with the process stream.The EPCS (Ensemble Particle Concentration & Size) described in the following has been used to obtain detailed size distribution measurements in powder production facilities at two second intervals, and has been successfully used for automatic feedback control.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100508
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    Non-Invasive Size-Control of Pneumatically Conveyed Particles (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 353-356 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Investigations on the size control of pneumatically conveyed coarse particles were carried out using a microphone which detects the structure-borne sound caused by the impact of the particles on the pipe wall. Modes of eigenvibrations of the pipes are excited up to a maximum frequency, which decreases with increasing particle size. In an assembly of different sized particles, the lower frequencies are more stimulated as the fraction of larger particles increases. Changes in the particle size distribution are detected by analysing the intensities of the vibration modes which are set up in the walls of the tube by particle impact. One application is the monitoring of the upper range of a particle size distribution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100610
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    Study of initial- and transition-state solvation in the solvolysis of tert-butyl halides in alcohols from infinite dilution activity coefficients (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 133-138 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Gibbs energies of activation of the solvolytic reactions of tert-butyl halides (chloride, bromide and iodide) in eight mono-alcohols and eight di-alcohols were dissected into contributions from the initial state and transition state. The unified approach proposed by Abraham was applied and the various factors making up the overall solvent effect in both states were identified and compared. To perform this study, the Gibbs energies of transfer of the initial state were calculated using the infinite dilution activity coefficient values of the solutes in the solvents, γ∞. These values were determined from the UNIFAC group-contribution method, with the modified Flory-Huggins equation in the combinatorial term and with group interaction parameters from the Parameter Table exclusively based on experimental γ∞ data reported in the literature. It is concluded that solvent polarizability and polarity-HBD acidity and cavity effects during the activated process are mainly due to transition-state contributions.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060302
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    [4] Metacyclophane: STO-3G molecular structure, strain energy and CNDO/S—Cl electronic transition energies (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 163-170 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular structure of [4] metacyclophane is optimized at the ab initio STO-3G SCF level and a genuine minimum is located. In the STO-3G structure the benzene ring is less bent and geometrically distorted than in the previously reported MNDO structure. Although some bond alternation is calculated for the carbon-carbon bond lengths of the bent benzene ring, their values still fall in the range of highly delocalized compounds. Despite the fact that the STO-3G strain energy [SE(tot.)] is larger than the corresponding MNDO strain energy, the distribution of SE(tot.) over the bent benzene ring [SE(bb.)] and the oligomethylene bridge [SE(br.)] is similar. To facilitate the hitherto unsuccesful identification of [4] metacyclophane, its electronic transition energies were calculated with CNDO/S-CI using the STO-3G geometry as input geometry. The reliability of the CNDO/S-CI results was assessed by a comparison of calculated and experimental electronic transition energies for p- and, m-xylene, [5] para- and [5] metacyclophane and [4] paracyclophane following the same approach.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060307
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    Kinetics and mechanism of electron transfer reactions of aquo-thallium(III) and coordinated thallium(III). Reduction of thallium(III) and chlorothallium(III) complexes by L-ascorbic acid in aqueous acid medium (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 179-186 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The stoichiometry of the reaction of TIIII with ascorbic acid (H2A) in the presence and absence of chloride ion conforms to TIIII + H2A 〉 TII + 2H+ + A. where A is dehydroascorbic acid. The reaction exhibits complex kinetics and the reactivity of various chlorothallium (III) species decreases in the order of [TIOH]2+ 〉 TI3+ 〉 [TICI]2+ 〉 [TICI2]+ 〉 TICI3 〉 [TICI4]-. The mass balance relationship was employed to calculate the equilibrium concentration of the chloride ion for evaluation of the rate constants.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060309
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    IUPAC Commission on Physical Organic Chemistry (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 193-194 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060311
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    Theoretical studies of substituent effects on thermal eliminations of aryl ethyl carbonates and S-aryl O-ethyl thiocarbonatesDetermination of Reactivity by MO Theory. Part 82. (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 215-222 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Substituent effects on the thermal elimination reactions of carbonates and thiocarbonates were investigated MO theoretically using the AM1 method. For both substrates, an electron-withdrawing group is found to facilitate the decomposition. A two-step process is favoured by carbonates, whereas one- and two-step processes can compete in the pyrolysis of thiocarbonates. The ability to transmit substituent effect is greater with oxygen (carbonates) than with sulphur (thicarbonates) in contrast to the experimental results of Taylor and co-workers. Modelling studies with replacement of the phenyl ring with a vinyl group are found to be justified in this type of work.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060404
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    Radical reactions of epoxides. 2.For Part 1, see Ref. 1. intramolecular competition between cyclopropylmethyl and oxiranylmethyl radical ring-opening rearrangementsInitial results presented at the 46th Northwest Regional Meeting of the American Chemical Society, LaGrande, OR, 1991. Taken from the Thesis of K. W. Krosley.2 (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 228-232 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The erythro-thioimidazole precursor to the cyclopropyloxiranylmethyl radical has been prepared. Treatment with 7-19 equiv. of triphenyltin hydride at 70°C gave only 3-cyclopropylprop-2-en-1-ol, the product of epoxide ring opening. No product in which the cyclopropyl ring had opened was observed. Kinetic analysis allowed the assignment of a lower limit for the rate of oxiranylcarbinyl radical rearrangements of 1 × 1010 s-1 at this temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060406
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    Calorimetric study of human serum albumin in water-dioxane mixtures (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 251-253 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The calorimetric isotherm of water sorption by solid human serum albumin (HSA) was measured in water-dioxane mixtures. This isotherm has been successfully described at low water contents in the solvent within the framework of the presented model. The adsorption equilibrium constant and the monolayer formation energy were estimated from this model. The interaction enthalpies of solid HSA with the solvent in water-rich mixtures do not differ essentially from the solution enthalpy of HSA in water. This means that the solvent water content may be sufficient for the intermolecular interactions of HSA suspended in a water-organic mixture to be similar to those in aqueous protein solution.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610060409
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    Crystal and moecular structure of N-nitro-N-methyl-p-nitroaniline: Analysis of substituent effects on the ring geometry and estimation of the Hammett substituent constant for the N-methylnitramino group (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 257-260 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal and molecular structure of N-nitro-N-methyl-p-nitroaniline was solved with good precision: R = 0·058 and average estimated standard deviation for bond lengths = 0·003 Å. Analysis of the geometry reveals that the NO2 attached to the N atom is strongly conjugated. Application of the HOSE model to its geometry and to geometries of 12 other para-substituted nitrobenzenes yields good linear regressions between canonical structure weights and Hammett σ values by interpolation, σ for the N(Me)NO2 group is estimated to 0·36.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060502
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    The Marcus cross relation for hydrogen-transfer reactions (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 281-286 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Marcus cross relation provides a tool to calculate cross rates from the corresponding identity rates and the equilibrium constant. Assumptions made in deriving the Marcus cross relation and conclusions which can be drawn from agreement or disagreement between experimental and calculated cross rates are discussed. For a small variation in identity rate constants, agreement between experimental and calculated cross rates are discussed. For a small variation in identity rate constants, agreement between experimental and calculated cross rates simply means that the rate constant of a hypothetical thermoneutral cross reaction has a value within the range covered by the identity rates. Whether or not this value corresponds to the mean value of logarithmic identity rate constants can only be checked for a large variation in identity rates. Therefore, a newly defined index M is used to relate the difference in experimental and calculated logarithmic rate constants to the variation in the logarithmic identity rates. Provided that the Marcus cross relation is not obeyed, this indicates non-additivity of kinetic parameters. Applying this analysis to protontransfer reactions between different transition metal acids and between 9-alkylflourenes and (9-alkylfluorenyl)lithium shows that claims about agreement or disagreement of experimental rate constants with the rate constants calculated by means of the Marcus cross relation have to be revised in part.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610060505
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    Hydrogen-bond basicity of nitriles (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 302-306 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A thermodynamic hydrogen-bond basicity scale, pKHB, and a spectroscopic hydrogen-bond basicity scale, Δν(OH), were measured which permitted the construction of the solute hydrogen-bond basicity scale, β2H, for 71 nitriles embracing a wide range of structures from trichloroacetonitrile to cyanamides. Field, resonance, and polarizability contributions of the X substituents to the hydrogen-bond basicity of XCN compounds were established. Steric effects do not contribute to the hydrogen-bond basicity of nitriles.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610060508
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    Masthead (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060601
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    Interaction of 3,4-diphenyl-1,2,5-thiadiazole 1,1-dioxide with proton donor solvents (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 341-346 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The UV spectra of 3,4-diphenyl-1,2,5-thiadiazole 1,1-dioxide (I) and that of its thiadiazoline and thiadiazolidine derivatives were measured in several aprotic and protic solvents. Strong specific interactions of I with protic solvents are observed and the formation of stable carbinolamine type derivatives of I with methanol or ethanol is proposed. Spectroscopic data (UV, 1H and 13C NMR) and electrochemical evidence for their formation are given and a new thiadiazoline derivative of I (3-ethoxy-2-methyl-3,4-diphenyl-1,2,5-thiadiazoline 1,1-dioxide) was synthesized. The equilibrium constant for the reaction of I with ethanol is reported.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610060605
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    Kinetic solvent isotope effect studies on the methanolysis of 1-phenylethyl chlorides (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 361-366 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The negative slope (ΔρY+ 〈 0) of the Hammett-type plot using kinetic solvent isotope effect, log kSOH/kSOD versus σ+, for methanolysis of 1-(Y-phenyl)ethyl chlorides is rationalized by an ion-pair mechanism in which a solvent molecule attacks the relatively stable carbocation formed in the pre-equilibrium.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610060608
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    Nucleophilic substitution reactions of isopropyl benzenesulphonates with anilines and benzylamines (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 357-360 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nucleophilic substitution reactions of isopropyl arenesulphonates with anilines and benzylamines in acetonitrile at 65·0°C were investigated. The cross-interaction constants ρxz (and βxz) between substituents in the nucleophile (X) and leaving group (Z) are positive and relatively small. The transition state (TS) variation is consistent with that predicted by the More O'Ferrall-Jencks diagram, as expected from the positive ρxz. The small magnitude of ρxz correctly reflects a relatively loose TS structure, in contrast to the tight TS for ethyl (or methyl) derivatives under similar reaction conditions.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610060607
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    Masthead (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060701
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  • 95
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    Electronic Resource
    Tuning intramolecular carbenic insertions (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 376-379 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The 1,2-carbenic hydride shift of neopentylmethoxycarbene was suppressed by the methoxy substituent. Thermally activated hydride shifts were observed with phenoxymethylmethoxycarbene and phenoxymethyltrifluoro-ethoxycarbene, where appropriate potentiating substituents were introduced at both the migration origin and the migration terminus. Similarly, the 1,3-CH insertion reaction of tert-butylfluorocarbene could be induced by thermal activation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060611
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  • 96
    Electronic Resource
    Electronic Resource
    Ion-molecule pairs as intermediates in solvolysis. Catalysis by the pyridine leaving group on the elimination reaction (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 374-375 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solvolysis of the 1-(1-methyl-1-phenylethyl)pyridinium cation (1-P+) in 25% (v/v) acetonitrile in water at 60°C provides the alcohol 2-hydroxy-2-phenylpropane (1-OH) as the main product along with the alkene 2-phenylpropene (3). The formation of the elimination product 3 is promoted by the leaving pyridine. Thus, eight times more 3 is obtained from 1-P+ than from the protonated ether 1-OMeH+. Hydron abstraction by the leaving pyridine is only two times less efficient than with AcO- as leaving group. The results indicate that the ion-molecule pair 1+ -P has a significant lifetime. The elimination product is formed mainly from the ion-molecule pair. The free carbocation yields almost exclusively the substitution product.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060610
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  • 97
    Electronic Resource
    Electronic Resource
    Temprature dependence of the deuterium isotope effect in the deprotonation of some nitroalkanes by anionic bases (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 393-398 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The temperature dependences of rates and deuterium isotope effects were determined for the deprotonation of 1-phenyl-1-nitroethane (1), its analogue 1-d, 1-phenyl-2-nitropropane (2) and its analogue 2-d by methoxide in methanol, ethoxide in ethanol, hydroxide/methoxide in 50% (v/v) methanol-water and hydroxide in water. The isotope effects varied little with substrate or solvent-base combination. kH/kD at 30°C was between 6·0 and 7·1 in all cases. The temperature dependences varied considerably [AaH/AaD = 0·14-1·35 and EaD - EaH 0·95-2·29 kcal mol-1 (1 kcal = 4·184 kJ)]. AaH/AaD was lower with 1-phenyl-1-nitroethane than with 1-phenyl-2-nitropropane, but there was no consistent variation with solvent/base.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060703
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  • 98
    Electronic Resource
    Electronic Resource
    Microwave activation of the mutarotation of α-D-glucose: An example of an interinsic microwave effect (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 407-411 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mutarotation reaction of α-D-glucose in ethanol-water solvent in a modified commercial microwave oven, when compared with control reactions carried out at identical temperatures, shows a non-thermal microwave effect, evidenced both by a more rapid reaction and by a change in relative amounts of α- and β-D-glucose over time.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060705
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  • 99
    Electronic Resource
    Electronic Resource
    Magnetic field effects upon photochemistry of bifuctional chain molecules (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 381-392 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: External magnetic field effects are discussed for three typical examples of photoreactions involving biradical intermediates: photo-induced intramolecular electron transfer in chain molecules D—(CH2)n—A consisting of an electron donor (D) and an acceptor (A), intramolecular hydrogen abstraction in bifunctional species :X—(CH2)n—YH containing a hydrogen donor (YH) and an acceptor (:X in the excited triplet state) and photochemical homolytic ring opening of a cyclic ketone which yields a biradical consisting of an acyl and an alkyl group. There has been progress in the elucidation of reaction mechanisms through the analysis of magnetic field effects on lifetimes of reaction intermediates and product yields in radical reactions involving biradicals. Extremely small interactions such as the Zeeman energy and hyperfine interaction may give rise to a large change in the distribution of photo-products derived from bifunctional chain molecules.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060702
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  • 100
    Electronic Resource
    Electronic Resource
    Evidence for the presence of the CH-π-interacted ap-conformers of benzyl formates (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 399-406 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to examine the preferred conformations of benzyl, 1-phenylethyl and cumyl formates, lanthanoid-induced shifts (LIS) of 1H and 13C NMR and difference NOE spectra of these esters were measured. The measurements showed that a folded conformer capable of forming intramolecular CH-π interaction are predominant with all three series of formate esters. The LIS and other experiments suggested the coexistence of considerable amounts of extended conformers, however. As the ester group is enforced to take supposedly unfavourable ap-conformation in the CH-π contiguous folded conformer, the predominance of the conformer was a surprise and needed explanation. The NOE experiments on a series of para-substituted benzyl formates, XC6H4CH2OCHO (X = CH3O, CH3, H, Cl, NO2), showed that the enhancement of aromatic proton signals (ortho and meta) induced by the irradiation of formyl proton increases gradually as the substituent becomes more electron donating, whereas the enhancement of benzylic (α) proton signal remains constant irrespective of the nature of the substituent. This can be explained by assuming that the CH-π contiguous folded conformer is in equilibrium with the extended conformer. The trend of the substituent effect supports the hydrogen bond-like nature of the CH-π interaction. A similar trend was also observed with substituted 1-phenylethyl formates. Hence the unexpected stability of the ap-conformer of benzyl formates could be ascribed to the stabilization due to the CH-π interaction.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060704
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