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12. Pierre Sigwalt, Otto Vogl Dec 1999

12. Pierre Sigwalt, Otto Vogl

Otto Vogl

No abstract provided.


17th International Herman F. Mark Symposium: Polypropylene - A Material Of The Future, Otto Vogl, Helga Roder Dec 1999

17th International Herman F. Mark Symposium: Polypropylene - A Material Of The Future, Otto Vogl, Helga Roder

Otto Vogl

No abstract provided.


13. Josef Schurz, Otto Vogl Nov 1999

13. Josef Schurz, Otto Vogl

Otto Vogl

No abstract provided.


14. Paolo Galli, Otto Vogl, Anna Maria Marcon-Galli Oct 1999

14. Paolo Galli, Otto Vogl, Anna Maria Marcon-Galli

Otto Vogl

No abstract provided.


15. Clement Henry Bamford, Otto Vogl, Daphne Stephen-Bamford Sep 1999

15. Clement Henry Bamford, Otto Vogl, Daphne Stephen-Bamford

Otto Vogl

No abstract provided.


16. Eli M. Pearce, Otto Vogl, Judith Pearce Aug 1999

16. Eli M. Pearce, Otto Vogl, Judith Pearce

Otto Vogl

No abstract provided.


17. Hermann Klare, Otto Vogl, Burkart Philipp Jul 1999

17. Hermann Klare, Otto Vogl, Burkart Philipp

Otto Vogl

No abstract provided.


Particle Pressure And Marginal Stability Limits For A Homogeneous Monodisperse Gas-Fluidized Bed: Kinetic Theory And Numerical Simulations, Ashok S. Sangani, Donald L. Koch Jul 1999

Particle Pressure And Marginal Stability Limits For A Homogeneous Monodisperse Gas-Fluidized Bed: Kinetic Theory And Numerical Simulations, Ashok S. Sangani, Donald L. Koch

Ashok S. Sangani

A linear stability analysis is performed for the homogeneous state of a monodisperse gas-fluidized bed of spherical particles undergoing hydrodynamic interactions and solid-body collisions at small particle Reynolds number and finite Stokes number. A prerequisite for the stability analysis is the determination of the particle velocity variance which controls the particle-phase pressure. In the absence of an imposed shear, this velocity variance arises solely due to the hydrodynamic interactions among the particles. Since the uniform state of these suspensions is unstable over a wide range of values of particle volume fraction &phgr; and Stokes number St, full dynamic simulations cannot …


18. Dieter Freitag, Otto Vogl, Karina Rigby Jun 1999

18. Dieter Freitag, Otto Vogl, Karina Rigby

Otto Vogl

No abstract provided.


19. Makoto Okawara, Otto Vogl, Teiji Tsuruta, Seiichi Nakahama May 1999

19. Makoto Okawara, Otto Vogl, Teiji Tsuruta, Seiichi Nakahama

Otto Vogl

No abstract provided.


20. Hiroshi Inagaki, Otto Vogl, Takeshi Fukuda, Masaki Tsuji Apr 1999

20. Hiroshi Inagaki, Otto Vogl, Takeshi Fukuda, Masaki Tsuji

Otto Vogl

No abstract provided.


21. Teiji Tsuruta, Otto Vogl Mar 1999

21. Teiji Tsuruta, Otto Vogl

Otto Vogl

No abstract provided.


Evaluation Of Liquid Extraction Potentials For Downstream Separation Of 1,3-Propanediol, Janusz J. Malinowski Jan 1999

Evaluation Of Liquid Extraction Potentials For Downstream Separation Of 1,3-Propanediol, Janusz J. Malinowski

Janusz J. Malinowski

The application of liquid-liquid extraction for the downstream separation of 1,3-propanediol from dilute aqueous solutions has been tested. Preliminary solvent screening was performed using the group contribution method. Experimental verification of the predictions revealed that the distribution of 1,3-propanediol into organic solvents is not good enough to make simple extraction efficient.


Efect Of The Intraparticle Mass Transport Limitations On Temperature Profiles And Catalytic Performance Of The Reverse-Flow Reactor For The Partial Oxidation Of Methane To Synthesis Gas, Krzysztof Gosiewski, Ulrich Bartmann, Marek Moszczynski, Leslaw Mleczko Jan 1999

Efect Of The Intraparticle Mass Transport Limitations On Temperature Profiles And Catalytic Performance Of The Reverse-Flow Reactor For The Partial Oxidation Of Methane To Synthesis Gas, Krzysztof Gosiewski, Ulrich Bartmann, Marek Moszczynski, Leslaw Mleczko

Krzysztof Gosiewski

A mathematical model of the reverse-flow reactor for the catalytic conversion of methane to synthesis gas is presented. The model contains 8 partial diferential equations and 6 algebraic equations. The analysis performed and the literature data suggest a considerable in#uence of the difusional resistance in the catalyst pellet upon the actual rate of reactions occurring in the process. A simple approximate procedure is developed for the estimation of the efectiveness factor of the reactions, which enables the resistance due to internal difusion to be taken into account at any point of the reactor without resorting to numerical integration of the …


Characterization Of Oxidation Products Of Tnt Metabolism In Aquatic Phytoremediation Systems Of Myriophyllum Aquaticum, R. Bhadra, R. J. Spanggord, D. G. Wayment, J. B. Hughes, Jacqueline V. Shanks Jan 1999

Characterization Of Oxidation Products Of Tnt Metabolism In Aquatic Phytoremediation Systems Of Myriophyllum Aquaticum, R. Bhadra, R. J. Spanggord, D. G. Wayment, J. B. Hughes, Jacqueline V. Shanks

Jacqueline V. Shanks

TNT transformation processes in sediment-free, “natural”, aquatic phytoremediation systems of Myriophyllum aquaticum were investigated with specific interest in oxidation products. Extraction procedures combining liquidliquid extractions and solid-phase extractions were developed for the isolation of the mostly acidic, oxidized TNT metabolites. Six compounds unique from the reduction products of TNT were isolated and characterized by UVvis, 1H, and 13C NMR spectroscopy, by mass spectroscopy, and by chemical synthesis where feasible. These compounds include 2-amino-4,6-dinitrobenzoic acid, 2,4-dinitro-6- hydroxy-benzyl alcohol, 2-N-acetoxyamino-4,6-dinitrobenzaldehyde, 2,4-dinitro-6-hydroxytoluene, and two binuclear metabolites unique from the customary azoxytetranitrotoluenes. The monoaryl compounds show clear evidence of oxidative transformations, methyl oxidation and/or …


Magnetic Resonance Imaging Analysis Of Molecular Mobility During Dissolution Of Poly(Vinyl Alcohol) In Water, Balaji Narasimhan, J. E.M. Snaar, R. W. Bowtell, S. Morgan, C. D. Melia, N. A. Peppas Jan 1999

Magnetic Resonance Imaging Analysis Of Molecular Mobility During Dissolution Of Poly(Vinyl Alcohol) In Water, Balaji Narasimhan, J. E.M. Snaar, R. W. Bowtell, S. Morgan, C. D. Melia, N. A. Peppas

Balaji Narasimhan

Magnetic resonance imaging is used to study changing microstructure and molecular motion during dissolution of poly(vinyl alcohol) (PVA) in water. One-dimensional water concentration profiles were measured as a function of distance from the polymer-solvent interface. Diffusion-weighted profiles were used to calculate the spatial variation of the self-diffusion coefficient of water. The results indicate that diffusion coefficient values decrease toward the glassy core of the polymer. Self-diffusion coefficient values within the dissolving polymer increase with increasing dissolution time, while those near the polymer-solvent interface remain fairly constant. The effect of PVA molecular weight on the dissolution mechanism was investigated, with MÌ„n …


Confirmation Of Conjugation Processes During Tnt Metabolism By Axenic Plant Roots, R. Bhadra, D. G. Wayment, J. B. Hughes, Jacqueline V. Shanks Jan 1999

Confirmation Of Conjugation Processes During Tnt Metabolism By Axenic Plant Roots, R. Bhadra, D. G. Wayment, J. B. Hughes, Jacqueline V. Shanks

Jacqueline V. Shanks

This paper examines processes in plants for the formation of fate products of TNT beyond its aminated reduction products, 2-amino-4,6-dinitrotoluene and 4-amino-2,6- dinitrotoluene. TNT metabolites were isolated and characterized in combination with temporal analyses of product profiles and 14C distribution, in microbe-free, axenic root cultures of Catharanthus roseus. Four unique TNTderived compounds were isolated. Using evidence from 1H NMR, mass spectroscopy, HPLC, acid hydrolysis, and enzymatic hydrolysis with â-glucuronidase and â-glucosidase, they were established as conjugates formed by reactions of the amine groups of 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene. From the mass spectral evidence, at least a six-carbon unit from the plant …


Determination Of Particle Size Distributions From Acoustic Wave Propagation Measurements, Ashok S. Sangani, Peter D. M. Spelt, Michael A. Norato, Lawrence L. Tavlarides Jan 1999

Determination Of Particle Size Distributions From Acoustic Wave Propagation Measurements, Ashok S. Sangani, Peter D. M. Spelt, Michael A. Norato, Lawrence L. Tavlarides

Ashok S. Sangani

The wave equations for the interior and exterior of the particles are ensemble averaged and combined with an analysis by Allegra and Hawley @J. Acoust. Soc. Am. 51, 1545 ~1972!# for the interaction of a single particle with the incident wave to determine the phase speed and attenuation of sound waves propagating through dilute slurries. The theory is shown to compare very well with the measured attenuation. The inverse problem, i.e., the problem of determining the particle size distribution given the attenuation as a function of frequency, is examined using regularization techniques that have been successful for bubbly liquids. It …


Entropy Generation In A Rectangular Packed Duct With Wall Heat Flux, Yasar Demirel, R. Kahraman Dec 1998

Entropy Generation In A Rectangular Packed Duct With Wall Heat Flux, Yasar Demirel, R. Kahraman

YASAR DEMIREL

The entropy generation due to heat transfer and friction has been calculated for fully developed, forced convection flow in a large rectangular duct. packed with spherical particles, with constant heat fluxes applied to both the top (heated) and bottom (cooled) wall. An approximate analytical expression for the velocity profile developed for packed bed with H/dp > 5 has been used together \vith the energy equation of fully developed flow to calculate the nonisothermal temperature profiles along the flow passage. The velocity prolile takes into account the increase in the velocity near the wall due to the higher voidage in this region …


Estimation Of The Entropy Of Vaporization At The Normal, Yasar Demirel Dec 1998

Estimation Of The Entropy Of Vaporization At The Normal, Yasar Demirel

YASAR DEMIREL

The entropy of vaporization at the normal boiling point has been estimated for binary and ternary azotropic mixtures containing water, alcohol or acetic acid. For this purpose, the Lee±Kesler correlation, developed originally for pure substances, is used with the appropriate mixing rules to estimate the heat of vaporization of the mixtures. Estimations for the entropy of vaporization of the 97 binary and 78 ternary mixtures are expressed as function of the ratio of the normal boiling point to average molecular weight. These expressions predict the entropy of vaporization satisfactorily, with less than 5% average deviation


Nanometer-Scale Probing Of Potential-Dependent Electrostatic Forces, Adhesion, And Interfacial Friction At The Electrode/Electrolyte Interface, Shane D. Campbell, Andrew C. Hillier Dec 1998

Nanometer-Scale Probing Of Potential-Dependent Electrostatic Forces, Adhesion, And Interfacial Friction At The Electrode/Electrolyte Interface, Shane D. Campbell, Andrew C. Hillier

Andrew C. Hillier

The atomic force microscope (AFM) was used to examine the influence of an applied electrochemical potential on the interfacial properties of the electrode/electrolyte interface. Measurements of electrostatic force, adhesion, and friction coefficient were performed at two different electrode surfaces: glassy carbon anda thin film of sulfonate-derivatized poly(aniline) (SPANi). At the carbon electrode, changes in electrostatic force between probe and substrate exhibited a potential-dependent transition from repulsive to attractive values at potentials negative and positive of the potential of zero charge (Epzc). Simultaneous measurements of tip-substrate adhesion and friction coefficient showed a change from low to high values over the same …


The Physicochemical Origins Of Coincident Epitaxy In Molecular Overlayers: Lattice Modeling Vs Potential Energy Calculations, Julie A. Last, Daniel E. Hooks, Andrew C. Hillier, Michael D. Ward Dec 1998

The Physicochemical Origins Of Coincident Epitaxy In Molecular Overlayers: Lattice Modeling Vs Potential Energy Calculations, Julie A. Last, Daniel E. Hooks, Andrew C. Hillier, Michael D. Ward

Andrew C. Hillier

The physicochemical basis for epitaxial stabilization of coincident molecular overlayers is illustrated by comparison of optimum overlayer-substrate configurations calculated with potential energy (PE) methods and a simple geometric lattice misfit modeling algorithm (EpiCalc) that neglects molecular orientations and intermolecular potentials. Using â-bis(ethylenedithio)tetrathiafulvalene triiodide (â-ET2I3), perylenetetracarboxylic diimide (PTCDI), and perylenetetracarboxylic dianhydride (PTCDA) overlayers on a graphite substrate as examples, both methods predict identical optimum azimuthal overlayer orientations for each overlayer that also agree with experimental observations. PE calculations for three hypothetical PTCDA overlayers, with identical lattice parameters but different molecular orientations, predict coincidence at the same azimuthal orientation for all overlayers. …


Entropy Generation In A Rectangular Packed Duct With Wall, Yasar Demirel, R. Kahraman Dec 1998

Entropy Generation In A Rectangular Packed Duct With Wall, Yasar Demirel, R. Kahraman

YASAR DEMIREL

The entropy generation due to heat transfer and friction has been calculated for fully developed forced convection flow in a large rectangular duct packed with spherical particles with constant heat fluxes applied to both the top heated and bottom cooled wall.


Packing Size Anetric Heating, Yasar Demirel, B.A. Abu Al-Saud, H.H. Ali, Y. Makkawi Dec 1998

Packing Size Anetric Heating, Yasar Demirel, B.A. Abu Al-Saud, H.H. Ali, Y. Makkawi

YASAR DEMIREL

An experimental and numerical investigation of fully developed forced convection in large rectangular packed ducts is presented. The horizontally oriented ducts have the length-to-separation distance ratio of L/H=16 with two aspect ratios of W/H=8 and 4. A constant heat flux is supplied to the top wall, while the bottom and side walls are insulated. Packing of hard polyvinyl chloride Raschig rings with outside diameters of 48 and 34 mm, and expanded polystyrene spheres with diameters of 48, 38 and 29 mm are used in the air flow passage. The pressure drop, the heat flux, axial and transverse temperature profiles of …


Enhancement Of Convection Heat-Transfer, Yasar Demirel, H.H. Al-Ali, B.A. Abu-Al-Saud Dec 1998

Enhancement Of Convection Heat-Transfer, Yasar Demirel, H.H. Al-Ali, B.A. Abu-Al-Saud

YASAR DEMIREL

Characteristics of wall-to-air heat transfer for a fully developed forced convection have been studied in a large rectangular packed duct with 160 cm heated length, 40 cm width, and for low bed equivalent diameter to particle diameter ratio. The separation distance between the top and bottom walls is 10 cm. A uniform heat ¯ux is supplied at the top wall, while the bottom wall is insulated. Raschig rings in two and spherical packing in three sizes have been used in the air ¯ow passage to investigate the enhancement of heat transfer due to packing. Temperature pro®les for the steady and …


Irreversibility Profiles In A Circular Couette Flow Of Temperature Dependent Materials, Yasar Demirel Dec 1998

Irreversibility Profiles In A Circular Couette Flow Of Temperature Dependent Materials, Yasar Demirel

YASAR DEMIREL

The irreversibility distributions have been calculated for a circular Couette flow of ethylene glycol with temperature dependent thermal conductivity and viscosity. The approximate series solutions of velocity and temperature fields are used to obtain the gradients to calculate the spatial entropy generation rate with narrowing gap of the Couette. It was found that the irreversibility distribution is relatively more uniform for a narrow-gap Couette.


Uso Del Diseño Experimental En La Obtención De Alúmina Activada Para La Remoción De Fluoruros Del Agua. Parte Ii: Resultados, R. Trejo-Vázquez, A. Bonilla-Petriciolet, L. Castañón-Ayala, J.M. Ruvalcaba Medina, H. Juárez Medina Dec 1998

Uso Del Diseño Experimental En La Obtención De Alúmina Activada Para La Remoción De Fluoruros Del Agua. Parte Ii: Resultados, R. Trejo-Vázquez, A. Bonilla-Petriciolet, L. Castañón-Ayala, J.M. Ruvalcaba Medina, H. Juárez Medina

Adrian Bonilla-Petriciolet

En esta segunda parte se muestran los resultados obtenidos a partir del esquema metodológico presentado en la primera parte para la preparación de alúmina activada destinada a la remoción de fluoruros del agua. Bajo las condiciones de preparación establecidas, se obtuvo un porcentaje de remoción de fluoruros del 65,25% para agua sintética con concentración inicial de 2 partes por millón de fluoruros, el cual es mayor al obtenido por una alúmina comercial que se probó bajo las mismas condiciones. Lo anterior sugiere que el proceso de preparación del adsorbente desarrollado según esta metodología es técnicamente satisfactorio y podría resultar interesante …