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Articles 1171 - 1200 of 1407

Full-Text Articles in Biochemical and Biomolecular Engineering

Thermodynamics And Bioenergetics, Yaşar Demirel, Stanley I. Sandler Mar 2002

Thermodynamics And Bioenergetics, Yaşar Demirel, Stanley I. Sandler

Papers in Thermal Mechanics

Bioenergetics is concerned with the energy conservation and conversion processes in a living cell, particularly in the inner membrane of the mitochondrion. This review summarizes the role of thermodynamics in understanding the coupling between the chemical reactions and the transport of substances in bioenergetics. Thermodynamics has the advantages of identifying possible pathways, providing a measure of the efficiency of energy conversion, and of the coupling between various processes without requiring a detailed knowledge of the underlying mechanisms. In the last five decades, various new approaches in thermodynamics, non-equilibrium thermodynamics and network thermodynamics have been developed to understand the transport and …

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Expression Of Active Human Factor Ix In Mammary Tissue And Of Milk Non Human Transgenic Mammals , William H. Velander, William N. Drohan Feb 2002

Expression Of Active Human Factor Ix In Mammary Tissue And Of Milk Non Human Transgenic Mammals , William H. Velander, William N. Drohan

Papers in Biotechnology

Recombinant Factor IX characterized by a high percentage of active protein can be obtained in the milk of transgenic animals that incorporate chimeric DNA molecules according to the present invention. Transgenic animals of the present invention are produced by introducing into developing embryos DNA that encodes Factor IX, such that the foreign DNA is stably incorporated in the DNA of germ line cells of the mature animal. Particularly efficient expression was accomplished using a chimeric construct comprising a mammary gland specific promoter, Factor IX cDNA that lacked the complete or any portion of the 5'-untranslated and 3'-untranslated region, which is …

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Modelling Of The Glass Phase In Fly Ashes Using Network Connectivity Theory, Mark R. Towler, Kenneth T. Stanton, Patrick Mooney, Robert G. Hill, Natalia Moreno, Xavier Querol Jan 2002

Modelling Of The Glass Phase In Fly Ashes Using Network Connectivity Theory, Mark R. Towler, Kenneth T. Stanton, Patrick Mooney, Robert G. Hill, Natalia Moreno, Xavier Querol

Chemical and Biochemical Engineering Faculty Research & Creative Works

The amorphous phase of fly ash dominates degradation behaviour because glass has a higher potential energy than the equivalent crystal structure and the variation of bond angles and distances in a glass make the bond breakage easier. It would be advantageous to predict the presence and subsequent degradability of glass on the basis of the solid-state chemistry of the fly ash. To this end, and inorganic polymer model was applied to a selection of European fly ashes to determine the value known as cross-link density (CLD). A cross-link density value of less than two implies that the material is amorphous …

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Ultrafast Flow Quantification With Segmented K-Space Magnetic Resonance Phase Velocity Mapping, Haosen Zhang, Sandra S. Halliburton, James R. Moore, Orlando P. Simonetti, Paulo R. Schvartzman, Richard D. White, George P. Chatzimavroudis Jan 2002

Ultrafast Flow Quantification With Segmented K-Space Magnetic Resonance Phase Velocity Mapping, Haosen Zhang, Sandra S. Halliburton, James R. Moore, Orlando P. Simonetti, Paulo R. Schvartzman, Richard D. White, George P. Chatzimavroudis

Chemical & Biomedical Engineering Faculty Publications

Magnetic resonance (MR) phase-velocity mapping (PVM) is routinely being used clinically to measure blood flow velocity. Conventional nonsegmented PVM is accurate but relatively slow (3–5 min per measurement). Ultrafast k-space segmented PVM offers much shorter acquisitions (on the order of seconds instead of minutes). The aim of this study was to evaluate the accuracy of segmented PVM in quantifying flow from through-plane velocity measurements. Experiments were performed using four straight tubes (inner diameter of 5.6–26.2 mm), under a variety of steady (1.7–200 ml/s) and pulsatile (6–90 ml/cycle) flow conditions. Two different segmented PVM schemes were …

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Biological Reduction Of Perchlorate In Ion Exchange Regenerant Solutions Containing High Salinity And Ammonium Levels, Tina M. Gingras, Jacimaria R. Batista Jan 2002

Biological Reduction Of Perchlorate In Ion Exchange Regenerant Solutions Containing High Salinity And Ammonium Levels, Tina M. Gingras, Jacimaria R. Batista

Civil and Environmental Engineering and Construction Faculty Research

The most promising technologies to remove perchlorate from water are ion exchange and biological reduction. Although successful, ion exchange only separates perchlorate from water; it does not eliminate it from the environment. The waste streams from these systems contain the caustic or saline regenerant solutions used in the process as well as high levels of perchlorate. Biological reduction could be used to treat the regenerant waste solutions from the ion exchange process. A treatment scheme, combining ion exchange and biodegradation, is proposed to completely remove perchlorate from the environment. Perchlorate-laden resins generate brines containing salt concentrations up to 6% or …

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Incorporation Of Cerium And Neodymium In A Uranyl Hydroxide Solid, Chang-Soo Kim, David J. Wronkiewicz, R. J. Finch, E. C. Buck Jan 2002

Incorporation Of Cerium And Neodymium In A Uranyl Hydroxide Solid, Chang-Soo Kim, David J. Wronkiewicz, R. J. Finch, E. C. Buck

Electrical and Computer Engineering Faculty Research & Creative Works

The migration behavior of radionuclides in a nuclear-waste repository will be influenced, in part, by their equilibrium solubilities in the presence of radionuclide-bearing solids and/or adsorption affinities as trace components onto the surfaces of solid host phases. Uranium phases that precipitate on the surface of altered spent nuclear fuel may thus influence the mobility of radionuclides released in the near-field environment, since by proximity, these will be the first phases that the radionuclides encounter following their release from the spent fuel matrix. We have evaluated the potential for incorporating radionuclides into crystalline compounds by precipitating uranyl phases from aqueous solutions …

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Inferring Liquid Chaotic Dynamics In Bubble Columns, M. Cassanello, F. Larachi, A. Kemoun, M. (Muthanna) H. Al-Dahhan, M. P. Dudukovic Nov 2001

Inferring Liquid Chaotic Dynamics In Bubble Columns, M. Cassanello, F. Larachi, A. Kemoun, M. (Muthanna) H. Al-Dahhan, M. P. Dudukovic

Chemical and Biochemical Engineering Faculty Research & Creative Works

Experiments Carried Out to Study the Liquid Displacements in Bubble Columns Via the Computer Automated Radioactive Particle Tracking Technique Are Analyzed by Means of Lagrangian and Qualitative Dynamics Tools. the Lagrangian Approach Yields the Detailed Motion Sequences of the Tracer as Entrained by the Fast Ascending Bubbles or by the Liquid Flow Alongside the Column Walls. the Qualitative Dynamics Tools, on the Other Hand, Provide Prima Facie Corroboration of Chaos in Liquid Motion based on an Analysis of the Volume-Averaged Kolmogorov Entropy and the Mutual Information Function. Other Features of the Chaotic Motion, the Reconstructed Attractors and the Radial and …

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Non-Repressing Carbon Sources For Alcohol Oxidase (Aoxi) Promoter Of Pichia Pastoris, Mehmet İnan, Michael M. Meagher Nov 2001

Non-Repressing Carbon Sources For Alcohol Oxidase (Aoxi) Promoter Of Pichia Pastoris, Mehmet İnan, Michael M. Meagher

Papers in Biochemical Engineering

The growth of Pichia pastoris in a mixture of either glycerol or glucose and methanol follows a diauxic growth, with C1, utilizing enzymes being repressed. Therefore, these carbon sources can not be used as a mixture with methanol to simultaneously grow P. pastoris and induce C1, utilizing enzymes, especially in shake flask cultures of AOX-deficient P. pastoris. Among the alternative carbon sources tested, alanine, sorbitol, mannitol and trehalose, did not repress β-gal production when methanol was used as an inducer in mut- strain of P. pastoris. Our results show that either one of alanine, sorbitol, …

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Monte Carlo Simulations Of Peptide Adsorption On Solid Surfaces (Monte Carlo Simulations Of Peptide Adsorption), D. Song, Daniel Forciniti Nov 2001

Monte Carlo Simulations Of Peptide Adsorption On Solid Surfaces (Monte Carlo Simulations Of Peptide Adsorption), D. Song, Daniel Forciniti

Chemical and Biochemical Engineering Faculty Research & Creative Works

Monte Carlo (MC) simulations of a short peptide in bulk water and at charged and neutral surfaces were performed. To pursue the objective of finding whether or not the water structure around the peptide changes upon adsorption and how these changes affect the orientation of the peptide at the surface, the water structure around the peptide in the bulk and at charged and neutral surfaces were compared by analyzing the pair correlation functions (PCFs) between selected groups in the peptide and the surrounding water. In general, evidence was obtained that water is not homogeneously distributed over the peptide surface.

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Characteristics And Sequence Of Phosphoglycolate Phosphatase From A Eukaryotic Green Alga Chlamydomonas Reinhardtii, Tarlan G. Mamedov, Kensaku Suzuki, Kenji Miura, Ken-Ichi Kucho, Hideya Fukuzawa Oct 2001

Characteristics And Sequence Of Phosphoglycolate Phosphatase From A Eukaryotic Green Alga Chlamydomonas Reinhardtii, Tarlan G. Mamedov, Kensaku Suzuki, Kenji Miura, Ken-Ichi Kucho, Hideya Fukuzawa

Papers in Biochemical Engineering

Phosphoglycolate phosphatase (PGPase), a key en¬zyme of photorespiration in photosynthetic organisms, was purified from Chlamydomonas reinhardtii. The en¬zyme was an ~65-kDa homodimer with a pI value of 5.1 composed of ~32-kDa subunits not connected by any S–S bridges. It was also highly specific for phosphoglycolate with a Km value of 140 μM and an optimal pH between 8 and 9. The activity was strongly inhibited by CaCl2, and it recovered competitively following the addition of MgCl2 or EGTA. A mobility shift was observed in SDS-polyacrylamide gel electrophoresis by the addition of CaCl2, indicating that the enzyme binds to Ca2+ . …

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The Effect Of Low Levels Of Zirconia Addition On The Mechanical Properties Of Hydroxyapatite, Mark R. Towler, I. R. Gibson Sep 2001

The Effect Of Low Levels Of Zirconia Addition On The Mechanical Properties Of Hydroxyapatite, Mark R. Towler, I. R. Gibson

Chemical and Biochemical Engineering Faculty Research & Creative Works

The effect of low levels of zirconia addition on the mechanical properties of hydroxyapatite was analyzed. Optimum amount of zirconia required to prevent decomposition of hydroxyapatite during sintering was determined. The particle size, morphology and surface area were measured and calcium to phosphorus ratio and trace element impurity content were determined by x-ray fluorescence. Low level addition of zirconia resulted in composites with better mechanical properties and minimum levels of decomposition.

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The Crystallisation Of Glasses From The Ternary Caf2-Caal2si2o8-P2 O5 System, A. Clifford, R. G. Hill, Mark R. Towler, D. J. Wood Aug 2001

The Crystallisation Of Glasses From The Ternary Caf2-Caal2si2o8-P2 O5 System, A. Clifford, R. G. Hill, Mark R. Towler, D. J. Wood

Chemical and Biochemical Engineering Faculty Research & Creative Works

A study of glasses from the ternary system CaF2-CaAl2Si2O8-P2O5 has been carried out. It has been shown that glasses with low phosphorus contents and high fluorite contents crystallise to fluorite. Fluorine reduces the glass transition temperature and is also required for the formation of fluorapatite (FAP). In the absence of fluorine in the glass no apatite phase is formed. Bulk nucleation of FAP is favoured for glasses with Ca:P ratios close to the apatite stoichiometry of 1.67 and with low crosslink densities. Thermal gravimetric analysis showed significant weight losses …

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The Effect Of Ethanol And Acetate On Protein Expression In Pichia Pastoris, Mehmet İnan, Michael M. Meagher Jul 2001

The Effect Of Ethanol And Acetate On Protein Expression In Pichia Pastoris, Mehmet İnan, Michael M. Meagher

Papers in Biochemical Engineering

Pichia pastoris is an excellent host for high-level heterologous gene expression, but there is still much interest in improving the productivity of recombinant protein production. P. pastoris produces a small amount of ethanol as a by-product during the glycerol fed-batch phase and the mixed-feed induction phase (glycerol-methanol) of high cell density fermentations, regardless of the phenotype (Mutf, Mut" or Mut-). We have investigated ethanol repression of the AOXl promoter using strains, GS115 (Mutf) and MC100-3 (Mut-), expressing an AOXI-lac2 fusion. The addition of 10 mg t1 ethanol at the start of methanol induction delayed P-galactosidase production and methanol utilization …

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Expression Of A Heterologous Protein C In Mammary Tissue Of Transgenic Animals Using A Long Whey Acidic Protein Promoter , William H. Velander, Henryk Lubton, William N. Drohan, Lothar Hennighausen Jul 2001

Expression Of A Heterologous Protein C In Mammary Tissue Of Transgenic Animals Using A Long Whey Acidic Protein Promoter , William H. Velander, Henryk Lubton, William N. Drohan, Lothar Hennighausen

Papers in Biotechnology

An isolated DNA sequence which regulates the expression of a heterologous gene composed of a mouse whey acidic protein promoter having a length of greater than about 2.4 kb extending upstream from the unique KpnI site in the mouse whey acidic protein gene is disclosed. Specifically a mouse whey acidic protein promoter of about 4.1-4.2 kb in length extending upstream from the unique KpnI site is preferred. This mouse whey acid protein promoter is operably linked to a DNA sequence encoding a heterologous polypeptide and used to prepare transgenic non-human mammals expressing the heterologous polypeptide in their milk. Particularly efficient …

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Modeling The Ultraviolet Photodegradation Of Rigid Polyurethane Foams, C. R. Newman, Daniel Forciniti Jul 2001

Modeling The Ultraviolet Photodegradation Of Rigid Polyurethane Foams, C. R. Newman, Daniel Forciniti

Chemical and Biochemical Engineering Faculty Research & Creative Works

Before the Montreal Protocol of 1987 and the subsequent phasing-out of chlorofluorocarbons (CFCs) in industrial applications, rigid polymer foams were made using these compounds as secondary blowing agents. The CFCs remain trapped in the gaseous part of the cellular foam structure, and once discarded these foams constitute a significant reservoir for the environmental release of ozone-depleting chemicals. Environmental degradation of the foam accelerates this process. Of particular interest in this work is the degradative effect of ultraviolet (UV) light on rigid polyurethane foams. Foams were subjected to accelerated weathering conditions and then viewed with a scanning electron microscope. The thin …

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Quantitative Analysis And Synthesis Of The Electrokinetic Mass Transport And Adsorption Mechanisms Of A Charged Adsorbate In Capillary Electrochromatography Systems Employing Charged Adsorbent Particles, B. A. Grimes, Athanasios I. Liapis Jun 2001

Quantitative Analysis And Synthesis Of The Electrokinetic Mass Transport And Adsorption Mechanisms Of A Charged Adsorbate In Capillary Electrochromatography Systems Employing Charged Adsorbent Particles, B. A. Grimes, Athanasios I. Liapis

Chemical and Biochemical Engineering Faculty Research & Creative Works

The dynamic mathematical model of Grimes and Liapis [J. Colloid Interf. Sci. 234 (2001) 223] for capillary electrochromatography (CEC) systems operated under frontal chromatography conditions is extended to accommodate conditions in CEC systems where a positively charged analyte is introduced into a packed capillary column by a pulse injection (analytical mode of operation) in order to determine quantitatively the electroosmotic velocity, electrostatic potential and concentration profiles of the charged species in the double layer and in the electroneutral core region of the fluid in the interstitial channels for bulk flow in the packed chromatographic column as the adsorbate adsorbs onto …

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A Preliminary Comparison Of The Mechanical Properties Of Chemically Cured And Ultrasonically Cured Glass Ionomer Cements, Using Nano-Indentation Techniques, Mark R. Towler, A. J. Bushby, R. W. Billington, R. G. Hill Jun 2001

A Preliminary Comparison Of The Mechanical Properties Of Chemically Cured And Ultrasonically Cured Glass Ionomer Cements, Using Nano-Indentation Techniques, Mark R. Towler, A. J. Bushby, R. W. Billington, R. G. Hill

Chemical and Biochemical Engineering Faculty Research & Creative Works

There is a requirement for a dental cement with properties comparable or superior to conventional glass ionomer cements (GICs) but with the command set properties of the resin modified GICs. The objective of this work was to show that the application of ultrasound to conventional Fuji IX commercial glass ionomer cement imparts a command set, whilst improving the short-term surface mechanical properties. Nano-indentation techniques were employed to highlight the improvements in hardness and creep resistance imparted to the cement through the application of ultrasound. The instant set imparted by the application of ultrasound provides improved surface hardness and creep, particularly …

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A Lagrangian Description Of Flows In Stirred Tanks Via Computer-Automated Radioactive Particle Tracking (Carpt), A. R. Rammohan, A. Kemoun, M. (Muthanna) H. Al-Dahhan, M. P. Dudukovic May 2001

A Lagrangian Description Of Flows In Stirred Tanks Via Computer-Automated Radioactive Particle Tracking (Carpt), A. R. Rammohan, A. Kemoun, M. (Muthanna) H. Al-Dahhan, M. P. Dudukovic

Chemical and Biochemical Engineering Faculty Research & Creative Works

In This Study, Computer-Automated Radioactive Particle Tracking (CARPT) is Implemented for the First Time in the Characterization of Flows in Stirred Tanks. Both the Experimental Set-Up Are Discussed. the CARPT Technique is Seen to Capture Qualitatively Most of the Important Flow Phenomena Observed in Stirred Tank Flows, Like the Two Recirculating Loops above and Below the Impeller and the Dead Zones at the Bottom of the Tank. the CARPT Data is Also Used to Extract ''Sojourn'' Time Distributions in Different Zones of the Reactor. These Distributions Are Used to Partially Quantify the Observed Dead and Active Zones in the Tank. …

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Studies On The Formation Of Dna-Cationic Lipid Composite Films And Dna Hybridization In The Composites, Murali Sastry, Vidya Ramakrishnan, Mrunalini Pattarkine, Krishna N. Ganesh May 2001

Studies On The Formation Of Dna-Cationic Lipid Composite Films And Dna Hybridization In The Composites, Murali Sastry, Vidya Ramakrishnan, Mrunalini Pattarkine, Krishna N. Ganesh

Faculty Works

The formation of composite films of double-stranded DNA and cationic lipid molecules (octadecylamine, ODA) and the hybridization of complementary single-stranded DNA molecules in such composite films are demonstrated. The immobilization of DNA is accomplished by simple immersion of a thermally evaporated ODA film in the DNA solution at close to physiological pH. The entrapment of the DNA molecules in the cationic lipid film is dominated by attractive electrostatic interaction between the negatively charged phosphate backbone of the DNA molecules and the protonated amine molecules in the thermally evaporated film and has been quantified using quartz crystal microgravimetry (QCM). Fluorescence studies …

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Particle Motion In Packed/Ebullated Beds By Ct And Carpt, Jinwen Chen, Novica Rados, Muthanna H. Al-Dahhan, Milorad P. Duduković, Duyen Nguyen, Krishniah Parimi May 2001

Particle Motion In Packed/Ebullated Beds By Ct And Carpt, Jinwen Chen, Novica Rados, Muthanna H. Al-Dahhan, Milorad P. Duduković, Duyen Nguyen, Krishniah Parimi

Chemical and Biochemical Engineering Faculty Research & Creative Works

Computed Tomography (CT) and Computer-Automated Radioactive Particle Tracking (CARPT) Were Used to Study the Gas Distribution and Incipient Particle Motion in a Packed/ebullated Bed in Which Gas and Liquid Are in Cocurrent Upflow. CT Scans Were Performed to Evaluate the Gas-Liquid Distributor and Gas Sparger for the Experiments, using a Perforated Plate Gas-Liquid Distributor (With 96 1-Mm Holes, Open Area of 0.1%) and a Gas Sparger (Cross-Shaped, with 16 3-Mm Holes), the Cross-Sectional Gas Holdup Distribution in the Packed/ebullated Bed Was Relatively Uniform, with Gas Holdup of About 0.11 in the Center and 0.09 Near the Wall of the Bed …

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Cfd Modeling Of Multiphase Flow Distribution In Catalytic Packed Bed Reactors: Scale Down Issues, Y. Jiang, Mohan R. Khadilkar, Muthanna H. Al-Dahhan, Milorad P. Dudukovic Mar 2001

Cfd Modeling Of Multiphase Flow Distribution In Catalytic Packed Bed Reactors: Scale Down Issues, Y. Jiang, Mohan R. Khadilkar, Muthanna H. Al-Dahhan, Milorad P. Dudukovic

Chemical and Biochemical Engineering Faculty Research & Creative Works

Flow Maldistribution in Either a Bench-Scale or Commercial Scale Packed Bed is Often Responsible for the Failure of the Scale Down Unit to Mimic the Performance of the Large Reactor. the Modeling of Multiphase Flow in a Bench-Scale Unit is Needed for Proper Interpretation of Reaction Rate Data Obtained in Such Units. Understanding the Mechanism of Flow Maldistribution is the First Step to Avoiding It. in Order to Achieve This Objective, Computational Fluid Dynamic (CFD) Simulations of Multiphase Flow under Steady State and Unsteady State Conditions in Bench-Scale Cylindrical and Rectangular Packed Beds Are Presented for the First Time. the …

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Statistical Characterization Of Macroscale Multiphase Flow Textures In Trickle Beds, Y. Jiang, M. (Muthanna) H. Al-Dahhan, M. P. Duduković Mar 2001

Statistical Characterization Of Macroscale Multiphase Flow Textures In Trickle Beds, Y. Jiang, M. (Muthanna) H. Al-Dahhan, M. P. Duduković

Chemical and Biochemical Engineering Faculty Research & Creative Works

Experimental Studies (Lutran Et Al., Ind. Engng Chem. Res. 30 (1991) 1270; Ravindra Et Al., Ind. Engng Chem. Res. 36 (1997) 5133) and Numerical Simulation (Jiang Et Al., Chem. Engng Sci. 54 (1999) 2409-2419) Lead to the Conclusion that Fluid Flow Distribution in Trickle Beds is a Function of Bed Structure (I.e. Porosity Distribution), Particle External Wetting and Inlet Superficial Velocities of the Two Fluids. in This Study, Quantitative Relationships among the above Parameters Are Developed in a Statistical Manner through a Series of Computational Fluid Dynamics Simulations. the Contribution of Capillary Forces to Liquid Maldistribution is Significant in the …

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Modeling And Analysis Of The Electrokinetic Mass Transport And Adsorption Mechanisms Of A Charged Adsorbate In Capillary Electrochromatography Systems Employing Charged Nonporous Adsorbent Particles, B. A. Grimes, Athanasios I. Liapis Feb 2001

Modeling And Analysis Of The Electrokinetic Mass Transport And Adsorption Mechanisms Of A Charged Adsorbate In Capillary Electrochromatography Systems Employing Charged Nonporous Adsorbent Particles, B. A. Grimes, Athanasios I. Liapis

Chemical and Biochemical Engineering Faculty Research & Creative Works

Mass-transfer systems based on electrokinetic phenomena (i.e., capillary electrochromatography (CEC)) have shown practical potential for becoming powerful separation methods for the biotechnology and pharmaceutical industries. A dynamic mathematical model, consisting of the momentum balance and the Poisson equations, as well as the unsteady-state continuity expressions for the cation and anion of the background electrolyte and of a positively charged analyte (adsorbate), is constructed and solved to determine quantitatively the electroosmotic velocity, the electrostatic potential, the concentration profiles of the charged species in the double layer and in the electroneutral core region of the fluid in the interstitial channels for bulk …

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Gas Holdup In A Trayed Cold-Flow Bubble Column, A. Kemoun, N. Rados, F. Li, M. (Muthanna) H. Al-Dahhan, M. P. Dudukovic', P. L. Mills, T. M. Leib, J. J. Lerou Feb 2001

Gas Holdup In A Trayed Cold-Flow Bubble Column, A. Kemoun, N. Rados, F. Li, M. (Muthanna) H. Al-Dahhan, M. P. Dudukovic', P. L. Mills, T. M. Leib, J. J. Lerou

Chemical and Biochemical Engineering Faculty Research & Creative Works

An Experimental Study Was Performed to Investigate the Effect of Sieve Trays on the Time-Averaged Gas Holdup Profiles and the overall Gas Holdup in a Cold-Flow Bubble Column that Was Scaled-Down from a Commercial Unit. Γ-Ray Computed Tomography (CT) Was Used to Scan the Column at Several Axial Locations in the Presence and Absence of Trays from Which the Local Variation of the Gas Holdup Was Extracted. the overall Gas Holdup Was Also Determined using the Same Configuration by Comparing the Expanded and Static Liquid Heights. Air and Water Were Used as the Gas-Liquid System. the Superficial Gas and Liquid …

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Prediction Of Axial Liquid Velocity Profile In Bubble Columns, Yuanxin Wu, M. (Muthanna) H. Al-Dahhan Feb 2001

Prediction Of Axial Liquid Velocity Profile In Bubble Columns, Yuanxin Wu, M. (Muthanna) H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Liquid Flow and Mixing Behavior in Bubble Columns is Partially Described by Means of Global Liquid Recirculation Velocity Profile. Due to the Complex Character of the Flow in Bubble Columns, the Prediction of the Axial Liquid Circulation is Still a Difficult Task. in This Work, the Following Correlation is Proposed for the Liquid Recirculation Profile: VLO/ VL(R)= 1 - 2.65 * N0.44 * C[R/r] 2.65, N0.442,c , Where N and C Are the Gas Radial Holdup Profile Parameters Evaluated by the Correlations Proposed by Wu, Ong and Al-Dahhan (Chemical Engineering Science, 56 (2001) 1207-1210). N = 2.188 X 103 …

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Predictions Of Radial Gas Holdup Profiles In Bubble Column Reactors, Yuanxin Wu, Boon Cheng Ong, M. (Muthanna) H. Al-Dahhan Feb 2001

Predictions Of Radial Gas Holdup Profiles In Bubble Column Reactors, Yuanxin Wu, Boon Cheng Ong, M. (Muthanna) H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Gas Holdup and its Profile Are Important Parameters to Be Characterized in Bubble Column Reactors. Proper Prediction of the Radial Gas Holdup Profiles is Necessary for Determining Liquid Mixing, Flow Regime Transition, Heat and Mass Transfer. in This Study, the Following Gas Holdup Profile Form, Which Can Be Fitted to the Observed Holdup Profiles, is Proposed: EG = EG (N + 2/n + 2 - 2c) [1 - C(R/R)n]. the Parameters N and C Needed to Describe the Gas Holdup Profile Are Correlated with Appropriate Dimensionless Groups. N = 2.188 X 103 ReG-0.598 Frg0.146 MoL-0.004, C = 4.32 X 10-2 …

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Comparison Of Single- And Two-Bubble Class Gas-Liquid Recirculation Models - Application To Pilot-Plant Radioactive Tracer Studies During Methanol Synthesis, Puneet Gupta, Muthanna H. Al-Dahhan, Milorad P. Dudukovic, Bernard A. Toseland Feb 2001

Comparison Of Single- And Two-Bubble Class Gas-Liquid Recirculation Models - Application To Pilot-Plant Radioactive Tracer Studies During Methanol Synthesis, Puneet Gupta, Muthanna H. Al-Dahhan, Milorad P. Dudukovic, Bernard A. Toseland

Chemical and Biochemical Engineering Faculty Research & Creative Works

Radioactive Gas Tracer Measurements Conducted during Liquid-Phase Methanol Synthesis from Syngas in a Pilot-Scale Slurry Bubble Column at the Alternate Fuels Development Unit (AFDU), La Porte Have Been Compared with Simulations from Two Mechanistic Reactor Models - Single-Bubble Class Model (SBCM) and Two-Bubble Class Model (TBCM). the Model Parameters Are Estimated from an Independent Sub-Model Gas and Liquid Recirculation, and the Long-Time-Averaged Slip Velocity between the Gas and Liquid/slurry in the Column Center Can Be as High as 50-60 Cm/s Depending on the Operating Conditions. Comparison of Experimental Data with Simulation Results from the Two Models Indicates that Accurate Description …

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Hydrodynamics Of Churn Turbulent Bubble Columns: Gas-Liquid Recirculation And Mechanistic Modeling, Puneet Gupta, Booncheng Ong, Muthanna H. Al-Dahhan, Milorad P. Dudukovic, Bernard A. Toseland Jan 2001

Hydrodynamics Of Churn Turbulent Bubble Columns: Gas-Liquid Recirculation And Mechanistic Modeling, Puneet Gupta, Booncheng Ong, Muthanna H. Al-Dahhan, Milorad P. Dudukovic, Bernard A. Toseland

Chemical and Biochemical Engineering Faculty Research & Creative Works

A Phenomenological (Mechanistic) Model Has Been Developed for Describing the Gas and Liquid/slurry Phase Mixing in Churn Turbulent Bubble Columns. the Gas and Liquid Phase Recirculation Rates in the Reactor, Which Are Needed as Inputs to the Mechanistic Reactor Model Are Estimated Via a Sub-Model Which Uses the Two-Fluid Approach in Solving the Navier-Stokes Equations. This Sub-Model Estimates the Effective Bubble Diameter in the Reactor Cross-Section and Provides a Consistent Basis for the Estimation of the Volumetric Mass Transfer Coefficients. the Strategy for the Numerical Solution of the Sub-Model Equations is Presented Along with the Simulation Results for a Few …

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Cationic Surfactant Mediated Hybridization And Hydrophobization Of Dna Molecules At The Liquid/Liquid Interface And Their Phase Transfer, Murali Sastry, Ashavani Kumar, Mrunalini Pattarkine, Vidya Ramakrishnan, Krishna N. Ganesh Jan 2001

Cationic Surfactant Mediated Hybridization And Hydrophobization Of Dna Molecules At The Liquid/Liquid Interface And Their Phase Transfer, Murali Sastry, Ashavani Kumar, Mrunalini Pattarkine, Vidya Ramakrishnan, Krishna N. Ganesh

Faculty Works

Hybridization of complementary oligonucleotides mediated by a cationic surfactant at the water/hexane interface leads to hydrophobic, double-helical DNA which may be readily phase transferred to the organic phase and cast into thin films on solid substrates.

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Purification And Characterization Of Crystallins By Aqueous Two-Phase Extraction, Ondrea Bermudez, Daniel Forciniti Jan 2001

Purification And Characterization Of Crystallins By Aqueous Two-Phase Extraction, Ondrea Bermudez, Daniel Forciniti

Chemical and Biochemical Engineering Faculty Research & Creative Works

Crystallins are a family of water-soluble proteins that constitute up to 90% of the water-soluble proteins in mammalian eye lenses. We present in this paper an alternative purification method for these proteins using polyethylene glycol/dextran aqueous two-phase extraction. Under the appropriate conditions, we were able to recover the γ-crystallin fraction essentially free of the remaining proteins. High concentrations of salt at a neutral pH maximize the recovery of γ-crystallins in the top phase and minimize the contamination by the other proteins present in the lenses. The proposed protocol decreases the separation time by about 50%. The complex partition behavior observed …

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