14 Matching Results

Search Results

Advanced search parameters have been applied.

Process development studies on the bioconversion of cellulose and production of ethanol

Description: Preliminary studies show minimal conversion of wood by sulfur dioxide at pressures of 38 psi at room temperature. Evaluation studies of Rut-C-30 and Rut-L-5 Trichoderma viride strains were compared. Studies on the continuous production system by manipulating temperature, pH, Tween 80 level substrate concentration, and dilution rate were performed. The known major components of cellulases were characterized. Studies on the reduction of the cost of producing sugar from corn stover were performed. Development of medium for continuous ethanol fermentation is discussed. Experiments show that the growth limiting factors for continuous fermentation were in the yeast extract. Biotin, pantothenic acid, and pyridoxine appear to be growth limiting factors. Addition of other vitamins had no effect on cell yield but increased ethanol production. The flash ferm process is discussed. Utilization of hemicellulose sugars is described. (DC)
Date: December 1, 1979
Creator: Wilke, C.R. & Blanch, H.W.
Partner: UNT Libraries Government Documents Department

Process development studies of the bioconversion of cellulose and production of ethanol. Semi annual report

Description: Progress in the following process development studio is reported: economic evaluation of hydrolysis and ethanol fermentation schemes, economic evaluation of alternative fermentation processes, raw materials evaluation, and evaluation of pretreatment process. Microbiological and enzymatic studies reported are: production of cellulase enzyme from high yielding mutants, hydrolysis reactor development, xylose fermentation, and xylanese production. Fermentation and separation processes include: process development studies on vacuum fermentation and distillation, evaluation of low energy separations processes, large scale hollow fiber reactor development. (MHR)
Date: April 1, 1981
Creator: Wilke, C.R. & Blanch, H.W.
Partner: UNT Libraries Government Documents Department

Feasibility studies for separation processes using environmentally sensitive hydrogels

Description: Temperature- and pH-sensitive hydrogels can be used to separate or concentrate proteins from dilute solution. Two possible separation processes are discussed here. Experimental partitioning data are used to compare the efficiencies of neutral, weakly acidic, weakly basic, and polyampholytic poly-N-isopropylacrylamide copolymer gels for separating cytochrome c from ovalbumin. For each process, attention is given to the influence of the solute partition coefficient and swelling equilibria on process efficiency.
Date: December 1, 1994
Creator: Sassi, A. P.; Blanch, H. W. & Prausnitz, J. M.
Partner: UNT Libraries Government Documents Department

Hydrogen-ion titrations of amino acids and proteins in solutions containing concentrated electrolyte

Description: This report describes a first attempt to quantify the net charge as a function of solution pH for lysozyme and {alpha}-chymotrypsin at 0.1 M, 1.0 M and 3.0 M ionic strength, (IS). The calculations are based on the residue (titratable group) pK{sub a}`s in the amino-acid sequence of the protein. To determine these pK{sub a}`s, a simple theory was used which assumes that the pK{sub a}`s are independent from each other in the protein and are equal to their pK{sub a} values in free amino-acid solution (Independent-Site Theory, IST). Residue pK{sub a}`s were obtained from amino-acid hydrogen-ion titrations at three different KCl concentrations corresponding to 0.1M, 1.0M and 3.0M ionic strength. After construction of a suitable apparatus, the experimental procedure and data reduction were computerized to perform a large number of titrations. Most measured pK{sub a}`s showed high reproducibility (the difference of pK{sub a} values observed between two experiments was less than 0.05). For IS = 0.1M, observed pK{sub a}`s agreed with literature values to within a few hundredths of a pH unit. Furthermore, the ionic-strength dependence of the pK{sub a}`s followed the trends reported in the literature, viz. pK{sub a} values decrease with increasing ionic strength until they reach a minimum at about IS = 0.5M. At still higher IS, pK{sub a}`s increase as the ionic strength rises to 3M. The known pK{sub a}`s of all titratable groups in a protein were used with the IST to give a first approximation of how the protein net charge varies with pH at high ionic strength. A comparison of the titration curves based on the IST with experimental lysozyme and {alpha}-chymotrypsin titration data indicates acceptable agreement at IS = 0.1M. However, comparison of measured and calculated titration curves at IS = 1M and IS = 3M indicates only quantitative agreement.
Date: December 1, 1994
Creator: Fergg, F.; Kuehner, D. E.; Blanch, H. W. & Prausnitz, J. M.
Partner: UNT Libraries Government Documents Department

Swelling equilibria for temperature-sensitive ampholytic hydrogels

Description: Temperature-sensitive N-isopropylacrylamide (NIPA)-based ampho-lytic hydrogels were synthesized by copolymerizing NIPA with the cationic monomer methacrylamidopropyl trimethylammonium chloride (MAPTAC) and the anionic monomer sodium styrene sulfonate (SSS). The total nominal charge density of the hydrogels was held constant at 8 mol % (dry basis), while the molar ratio of anionic to cationic moieties within the hydrogels was varied. Swelling equilibria were measured in water at 6C, and in aqueous sodium chloride solutions ranging in concentration from 10{sup {minus}5}to 5 M and temperature ranging from 6 to 56C. Consistent with expectations, the swelling behavior of the hydrogels was found to be controlled by temperature at low salt concentrations; as the sodium chloride concentration increased, temperature control of hydrogel swelling decreased. Slight antipolyelectrolyte behavior was observed for the hydrogel prepared with equal molar amounts of MAPTAC and SSS.
Date: September 1, 1992
Creator: Baker, J. P.; Stephens, D. R.; Blanch, H. W. & Prausnitz, J. M.
Partner: UNT Libraries Government Documents Department

Protein-salt binding data from potentiometric titrations of lysozyme in aqueous solutions containing KCl

Description: An existing method for potentiometric titrations of proteins was improved, tested and applied to titrations of the enzyme hen-egg-white lysozyme in aqueous solutions containing KCl at ionic strengths from 0.1 M to 2.0 M at 25 C. Information about the protein`s net charge dependence on pH and ionic strength were obtained and salt binding numbers for the system were calculated using a linkage concept. For the pH range 2.5--11.5, the net charge slightly but distinctly increases with increasing ionic strength between 0.1 M and 2.0 M. The differences are most distinct in the pH region below 5. Above pH 11.35, the net charge decreases with increasing ionic strength. Preliminary calculation of binding numbers from titration curves at 0.1 M and 1.0 M showed selective association of chloride anions and expulsion of potassium ions at low pH. Ion-binding numbers from this work will be used to evaluate thermodynamic properties and to correlate crystallization or precipitation phase-equilibrium data in terms of a model based on the integral-equation theory of fluids which is currently under development.
Date: March 1, 1997
Creator: Engmann, J.; Blanch, H.W. & Prausnitz, J.M.
Partner: UNT Libraries Government Documents Department

Bioprocessing in nonaqueous media - critical needs and opportunities

Description: Chemical conversion processes are pervasive in the U.S. industry. Whether they are used to make intermediate or final products or to remove hazardous materials from process waste streams, they are critical elements in the processing industries. Because of the mild reaction conditions, unique specificity, and selectivity, advanced processing concepts utilizing biocatalytic conversions are now being considered for many industrial uses, including those directly related to energy production and efficiency. Almost all bioprocessing systems currently used by industry utilize the biocatalysts (microorganisms or extracted enzymes) in a {open_quotes}natural{close_quotes} aqueous environment. This has resulted in many important large-scale applications, particularly in the fermentation and pharmaceutical industries. An exciting new area of bioprocessing research is now evolving - the use of biocatalysts in contact with nonaqueous media such as organic liquids or gases, or supercritical fluids. Such approaches could result in additional bioprocessing concepts that would result in a much broader range of utility, especially in energy production and energy-efficient conversion processes in the chemical industry. In fact, a whole new industry may be evolving.
Date: January 1, 1995
Creator: Scott, C. D.; Scott, T. C.; Blanch, H. W.; Klibanov, A. M. & Russell, A. J.
Partner: UNT Libraries Government Documents Department

Effect of secondary structure on the potential of mean force for poly-L-lysine in the alpha-Helix and beta-sheet conformations

Description: Because poly-L-lysine (PLL) can exist in the {alpha}-helix or {beta}-sheet conformation depending on solution preparation and solution conditions, PLL is a suitable candidate to probe the dependence of protein interactions on secondary structure. The osmotic second virial coefficient and weight-average molecular weight are reported from low-angle laser-light scattering measurements for PLL as a function of NaCl concentration, pH, and {alpha}-helix or {beta}-sheet content. Interactions between PLL molecules become more attractive as salt concentration increases due to screening of PLL charge by salt ions and at low salt concentration become more attractive as pH increases due to decreased net charge on PLL. The experimental results show that interactions are stronger for the {beta}-sheet conformation than for the {alpha}-helix conformation. A spherically-symmetric model for the potential of mean force is used to account for specific interactions not described by DLVO theory and to show how differences in secondary structure affect PLL interactions.
Date: October 30, 2001
Creator: Grigsby, J.J.; Blanch, H.W. & Prausnitz, J.M.
Partner: UNT Libraries Government Documents Department

Pore-size distributions of N-isopropylacrylamide (NIPA) hydrogels

Description: Pore-size distributions have been measured for N-isopropylacrylamide (NIPA) hydrogels at 25 and 32{degrees}C with swelling capacities 11.3 and 6.0 g swollen gel per g dry gel. The mixed-solute-exclusion method (introduced by Kuga) was used to obtain the experimental solute-exclusion curve which represents the amount of imbibed liquid inside the gel inaccessible for a solute of radius r. The pore-size distributions were obtained by using Casassa`s Brownian-motion model and numerically solving the Fredholm integral equation. The pore-size distributions of temperature-sensitive NIPA hydrogels are strongly dependent on temperature which determines swelling capacity. With increasing swelling capacity (from 6.0 to 11.3), the pore-size distribution shifts to higher mode values (27.3 to 50.6 {angstrom}) and to higher variance (1.07{center_dot}10{sup 3} to 3.58{center_dot}10{sup 3} {angstrom}{sup 2}).
Date: November 1, 1993
Creator: Walther, D. H.; Blanch, H. W. & Prausnitz, J. M.
Partner: UNT Libraries Government Documents Department