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Lower Saccharide Nanometric Materials and Methods

Description: A ceramic composition having at least one nanometric ceramic powder, at least one lower saccharide, and water. The composition is useful in many industrial applications, including preparation of stronger and substantially defect free green and sintered ceramic bodies.
Date: July 13, 2004
Creator: Schilling, Christopher H.; Tomasik, Piotr & Sikora, Marek
Partner: UNT Libraries Government Documents Department

High Activity catalysts for Polyols Production From C-6 Sugars

Description: Over the course of this project, many significant discoveries have been made in the process for the conversion of sorbitol to value added products. The object was developing a process for the production of propylene glycol (PG), ethylene glycol (EG), and glycerol from sorbitol.
Date: May 6, 2003
Creator: Werpy, Todd; Zacher, Alan; Frye, John; Peterson, Keith; Neuenschwander, Gary; Alderson, Eric et al.
Partner: UNT Libraries Government Documents Department

A Pilot Plant Scale Reactor/Separator for Ethanol from Cellulosics. ERIP/DOE Quarterly Reports 7, 8 and Final report

Description: The objective of this project was to develop and demonstrate a continuous low energy process for the conversion of cellulosics to ethanol. BPI's process involves a proprietary low temperature pretreatment step which allows recycle of the pretreatment chemicals and recovery of a lignin stream. The pretreated biomass is then converted to glucans and xylans enzymatically and these sugars simultaneously fermented to ethanol (SSF) in BPI's Continuous Stirred Reactor Separator (CSRS). The CSRS is a multi stage bio-reactor where the glucans are first converted to ethanol using a high temperature tolerant yeast stran, followed by xylan SSF on the lower stages using a second xylose fermenting yeast strain. Ethanol is simultaneously removed from the bio-reactor stages, speeding the fermentation, and allowing the complete utilization of the biomass.
Date: September 30, 1999
Creator: Cale, M. Clark & Moelhman, Mark
Partner: UNT Libraries Government Documents Department

A pilot plant scale reactor/separator for ethanol from cellulosics. ERIP/DOE quarterly report no. 3 and 4

Description: The objective of this project is to develop and demonstrate a continuous, low energy process for the conversion of cellulosics to ethanol. This process involves a pretreatment step followed by enzymatic release of sugars and the consecutive simultaneous saccharification/fermentation (SSF) of cellulose (glucans) followed by hemi-cellulose (pentosans) in a multi-stage continuous stirred reactor separator (CSRS). During quarters 3 and 4, we have completed a literature survey on cellulase production, activated one strain of Trichoderma reesei. We continued developing our proprietary Steep Delignification (SD) process for biomass pretreatment. Some problems with fermentations were traces to bad cellulase enzyme. Using commercial cellulase enzymes from Solvay & Genecor, SSF experiments with wheat straw showed 41 g/L ethanol and free xylose of 20 g/L after completion of the fermentation. From corn stover, we noted 36 g/L ethanol production from the cellulose fraction of the biomass, and 4 g/L free xylose at the completion of the SSF. We also began some work with paper mill sludge as a cellulose source, and in some preliminary experiments obtained 23 g/L ethanol during SSF of the sludge. During year 2, a 130 L process scale unit will be operated to demonstrate the process using straw or cornstalks. Co-sponsors of this project include the Indiana Biomass Grants Program, Bio-Process Innovation.
Date: December 1, 1998
Creator: Dale, M.C.; Moelhman, M. & Butters, R.
Partner: UNT Libraries Government Documents Department

Control of sugar transport and metabolism in Zymomonas mobilis. Final report

Description: This research deals with the physiology and genetics of sugar transport and metabolic control in Zymomonas mobilis. The specific objectives of the grant as as follows: First, the complex interactions of transcriptional, post-transcriptional and translational control mechanisms on regulation of the glf operon will be investigated. Second, the structure and function of the unique glucose facilitator will be examined by a combination of in vitro and in vivo approaches, making use of the genetically reconstituted system in E. coli. Third, the possibility that physical association or indirect interactions between the glucose facilitator and glucokinase are involved in metabolic control will be analyzed. Fourth, the Z. mobilis glucose transport and phosphorylation system will be utilized to metabolically engineer recombinant E. coli with altered cell pool metabolite profiles. Work on the third and fourth objectives is complete, work on the first and second objectives is progressing nicely. Publication of this work has been admittedly slow, due primarily to a change n location of the research program from the University of Nebraska to The Ohio State University. However, it should be noted that much of the unpublished data outlined below represented completed studies, and are contained in graduate student theses which are being prepared for submission this summer. Since a full year remains in the current funding period, and the new laboratory is now up and running, we fully expect to make reasonable progress on the remaining objectives and to publish the results in a timely fashion.
Date: September 1, 1995
Creator: Conway, T.
Partner: UNT Libraries Government Documents Department

Path of Carbon in Photosynthesis III

Description: Although the overall reaction of photosynthesis can be specified with some degree of certainty (CO{sub 2} + H{sub 2}O + light {yields} sugars + possibly other reduced substances), the intermediates through which the carbon passes during the course of this reduction have, until now, been largely a matter of conjecture. The availability of isotopic carbon, that is, a method of labeling the carbon dioxide, provides the possibility of some very direct experiments designed to recognize these intermediates and, perhaps, help to understand the complex sequence and interplay of reactions which must constitute the photochemical process itself. The general design of such experiments is an obvious one, namely the exposure of the green plant to radioactive carbon dioxide and light under a variety of conditions and for continually decreasing lengths of time, followed by the identification of the compounds into which the radioactive carbon is incorporated under each condition and time period. From such data it is clear that in principle, at least, it should be possible to establish the sequence of compounds in time through which the carbon passes on its path from carbon dioxide to the final products. In the course of shortening the photosynthetic times, one times, one ultimately arrives at the condition of exposing the plants to the radioactive carbon dioxide with a zero illumination time, that is, in the dark. Actually, in the work the systematic order of events was reversed, and they have begun by studying first the dark fixation and then the shorter photosynthetic times. The results of the beginnings of this sort of a systematic investigation are given in Table I which includes three sets of experiments, namely a dark fixation experiment and two photosynthetic experiments, one of 30 seconds duration and the other of 60 seconds duration.
Date: June 1, 1948
Creator: Benson, A.A. & Calvin, M.
Partner: UNT Libraries Government Documents Department

Sugar Transport and Metabolism in Thermotoga

Description: The work conducted under this grant demonstrated that the hyperthermophilic bacterium Thermotoga neapolitana carries out glucose and lactose transport in a sodium-dependent manner and that energization of anaerobic cells is required to observe transport. We also demonstrated that Thermotoga maritima carries out maltose and glucose transport using periplasmic sugar binding proteins. We began defining patterns of expression of genes encoding sugar transport and catabolic functions in both T. maritima and T. neapolitana. We began a collaborative effort to identify all the genes regulated at the transcriptional level in response to sugars substrates. These funds also allowed us to begin an examination of the functions of several periplasmic substrate binding proteins encoded in the genome of T. maritima.
Date: February 11, 2003
Creator: Noll, Kenneth M. & Romano, Antonio H.
Partner: UNT Libraries Government Documents Department

Batch Microreactor Studies of Lignin Depolymerization by Bases. 2. Aqueous Solvents

Description: Biomass feedstocks contain roughly 15-30% lignin, a substance that can not be converted to fermentable sugars. Hence, most schemes for producing biofuels assume that the lignin coproduct will be utilized as boiler fuel. Yet, the chemical structure of lignin suggests that it will make an excellent high value fuel additive, if it can be broken down into smaller compounds. From Fiscal year 1997 through Fiscal year 2001, Sandia National Laboratories participated in a cooperative effort with the National Renewable Energy Laboratory and the University of Utah to develop and scale a base catalyzed depolymerization (BCD) process for lignin conversion. SNL's primary role in the effort was to perform kinetic studies, examine the reaction chemistry, and to develop alternate BCD catalyst systems. This report summarizes the work performed at Sandia during Fiscal Year 1999 through Fiscal Year 2001 with aqueous systems. Work with alcohol based systems is summarized in part 1 of this report. Our study of lignin depolymerization by aqueous NaOH showed that the primary factor governing the extent of lignin conversion is the NaOH:lignin ratio. NaOH concentration is at best a secondary issue. The maximum lignin conversion is achieved at NaOH:lignin mole ratios of 1.5-2. This is consistent with acidic compounds in the depolymerized lignin neutralizing the base catalyst. The addition of CaO to NaOH improves the reaction kinetics, but not the degree of lignin conversion. The combination of Na{sub 2}CO{sub 3} and CaO offers a cost saving alternative to NaOH that performs identically to NaOH on a per Na basis. A process where CaO is regenerated from CaCO{sub 3} could offer further advantages, as could recovering the Na as Na{sub 2}CO{sub 3} or NaHCO{sub 3} by neutralization of the product solution with CO2. Model compound studies show that two types of reactions involving methoxy substituents on the aromatic ...
Date: May 1, 2002
Creator: MILLER, JAMES E.; EVANS, LINDSEY; MUDD, JASON E. & BROWN, KARA A.
Partner: UNT Libraries Government Documents Department

Fumaric acid: an overlooked form of fixed carbon in Arabidopsis and other plant species

Description: Photoassimilates are used by plants for production of energy, as carbon skeletons and in transport of fixed carbon between different plant organs. Many studies have been devoted to characterizing the factors that. regulate photoassimilate concentrations in different plant species. Most studies examining photoassimilate concentrations in C{sub 3} plants have focused on analyzing starch and soluble sugars. However, work presented here demonstrates that a number of C{sub 3} plants, including the popular model organism Arabidopsis thaliana (L.) Heynh., and agriculturally important plants, such as soybean [Glycine ma (L.) Merr.], contain significant quantities of furnaric acid. In fact, furnaric acid can accumulate to levels of several mg per g fresh weight in A-abidopsis leaves, often exceeding starch and soluble sugar levels. Furnaric acid is a component of the tricarboxylic acid cycle and, like starch and soluble sugars, can be metabolized to yield energy and carbon skeletons for production of other compounds. Fumaric acid concentrations increase with plant age and light intensity in Arabidopsis leaves. Arabidopsis phloem exudates contain significant quantities of fumaric acid, raising the possibility that fumaric acid may function in carbon transport.
Date: October 1, 2000
Creator: Chia, D.W.; Yoder, T.J.; Reiter, W.D. & Gibson, S.I.
Partner: UNT Libraries Government Documents Department

Gas-Solid Displacement Reactions for Converting Silica Diatom Frustules into MgO and TiO2

Description: Technology for the microfabrication of freely moving parts began with a Bell Labs microgear spun by an air jet, and electrostatic silicon micro motors in the mid-1980s. It continued with development work on micropositioning of optics, miniature heat exchangers, small fluidic devices, and chemical reaction chambers. Recently, there has been a great deal of interest centered on the design and manufacture of devices of nanometer proportions and this speculation has spawned a new industry named, nanotechnology. Despite the technological and economic promise of this technology, current commercial micro/mesofabrication methods have largely been based upon two-dimensional processing principles which is not well suited to the low-cost mass production of three-dimensional micro devices with complex geometries and meso/nanoscale features. Diatoms are three dimensional (3D) microstructures from nature that provide a practical alternative for nanotechnology and microfabrication. Diatoms (Figure 1) are single-celled micro algae that form rigid cell walls (frustules) composed of amorphous silica. Their dimensions can range from less than 1 micron to several hundreds of microns. They are distributed throughout the world in aquatic, semi-aquatic and moist habitats, and extremely abundant in freshwater and marine ecosystems. Diatoms are thought to be responsible for up to 25% of the world's net primary production of organic carbon (by transforming of carbon dioxide and water into sugars by photosynthesis). Approximately 10{sup 5} unique diatom frustule shapes have been claimed to exist in nature. The frustules are composed of two valves that fit together like a petri-dish, connected to each other by one or more girdle bands. The frustule wall consists of a nanoporous assembly of silica nanoparticles. They absorb soluble silica from water even at extremely low concentrations and metabolize and deposit it as an external skeleton. Continued reproduction of a single parent diatom can yield large numbers of descendant diatoms, each of which ...
Date: December 19, 2004
Creator: Kalem, Tugba
Partner: UNT Libraries Government Documents Department

Batch Microreactor Studies of Lignin Depolymerization by Bases. 1. Alcohol Solvents

Description: Biomass feedstocks contain roughly 10-30% lignin, a substance that can not be converted to fermentable sugars. Hence, most schemes for producing biofuels (ethanol) assume that the lignin coproduct will be utilized as boiler fuel to provide heat and power to the process. However, the chemical structure of lignin suggests that it will make an excellent high value fuel additive, if it can be broken down into smaller molecular units. From fiscal year 1997 through fiscal year 2001, Sandia National Laboratories was a participant in a cooperative effort with the National Renewable Energy Laboratory and the University of Utah to develop and scale a base catalyzed depolymerization (BCD) process for lignin conversion. SNL's primary role in the effort was to utilize rapidly heated batch microreactors to perform kinetic studies, examine the reaction chemistry, and to develop alternate catalyst systems for the BCD process. This report summarizes the work performed at Sandia during FY97 and FY98 with alcohol based systems. More recent work with aqueous based systems will be summarized in a second report.
Date: May 1, 2002
Creator: MILLER, JAMES E.; EVANS, LINDSEY; LITTLEWOLF, ALICIA & TRUDELL, DANIEL E.
Partner: UNT Libraries Government Documents Department

Improvements In Ethanologenic Escherichia Coli and Klebsiella Oxytoca

Description: The current Verenium cellulosic ethanol process is based on the dilute-acid pretreatment of a biomass feedstock, followed by a two-stage fermentation of the pentose sugar-containing hydrolysate by a genetically modified ethanologenic Escherichia coli strain and a separate simultaneous saccharification-fermentation (SSF) of the cellulosic fraction by a genetically modified ethanologenic Klebsiella oxytoca strain and a fungal enzyme cocktail. In order to reduce unit operations and produce a fermentation beer with higher ethanol concentrations to reduce distillation costs, we have proposed to develop a simultaneous saccharification co-fermentation (SScF) process, where the fermentation of the pentose-containing hydrolysate and cellulosic fraction occurs within the same fermentation vessel. In order to accomplish this goal, improvements in the ethanologens must be made to address a number of issues that arise, including improved hydrolysate tolerance, co-fermentation of the pentose and hexose sugars and increased ethanol tolerance. Using a variety of approaches, including transcriptomics, strain adaptation, metagenomics and directed evolution, this work describes the efforts of a team of scientists from Verenium, University of Florida, Massachusetts Institute of Technology and Genomatica to improve the E. coli and K. oxytoca ethanologens to meet these requirements.
Date: September 30, 2010
Creator: Nunn, Dr. David
Partner: UNT Libraries Government Documents Department

KINETICS OF THE HYDROLYSIS AND ALCOHOLYSIS OF TETRAPOLYPHOSPHATEESTERS ('ETHYLMETAPHOSPHATE')

Description: 'Ethyl metaphosphate' or tetrapolyphosphate esters are a potentially useful starting material for the preparation of polynucleotides. The kinetics of the reactions of the esters with excess water and ethanol have been measured by means of p{sup 31} n.m.r. and IR spectroscopy. Upon the addition of specific amounts of water or ethanol, substances could be prepared which consist mainly of linear tetrapoly-, tripoly- or pyrophosphate esters containing smeller amounts of other polyphosphates and orthophosphates in an equilibrium composition. Diethyl hydrogen orthophosphate reacts with cyclic polyphosphate esters to open the ring; with linear esters it reacts to form polyphosphates with a lesser degree of condensation. This latter reaction also proceeds to an equilibrium. No reactions between linear and cyclic polyphosphate esters were observed at room temperature, which implies that the rates of the disproportionation of the linear polyphosphate esters were low. Some organic solvents previously employed for the dehydrating polymerization of sugars, amino acids or nucleotides destroy the tetrapolyphosphate esters. The various substances now available from tetrapolyphosphate esters by the action of water or reactive solvents will differ in their capabilities of producing the dehydrating polymerization reaction. Thus, one may expect that very different products might result from very small differences in reaction conditions.
Date: March 1, 1965
Creator: Burkhardt, Gottfried; Klein, Melvin P. & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

Top Value-Added Chemicals from Biomass - Volume II—Results of Screening for Potential Candidates from Biorefinery Lignin

Description: This report evaluates lignin’s role as a renewable raw material resource. Opportunities that arise from utilizing lignin fit into one of three categories: 1)power, fuel and syngas (generally near-term opportunities) 2) macromolecules (generally medium-term opportunities) 3) aromatics and miscellaneous monomers (long-term opportunities). Biorefineries will receive and process massive amounts of lignin. For this reason, how lignin can be best used to support the economic health of the biorefinery must be defined. An approach that only considers process heat would be shortsighted. Higher value products present economic opportunities and the potential to significantly increase the amount of liquid transportation fuel available from biomass. In this analysis a list of potential uses of lignin was compiled and sorted into “product types” which are broad classifications (listed above as power—fuel—syngas; macromolecules; and aromatics). In the first “product type” (power—fuel—gasification) lignin is used purely as a carbon source and aggressive means are employed to break down its polymeric structure. In the second “product type” (macromolecules) the opposite extreme is considered and advantage of the macromolecular structure imparted by nature is retained in high-molecular weight applications. The third “product type” (aromatics) lies somewhere between the two extremes and employs technologies that would break up lignin’s macromolecular structure but maintain the aromatic nature of the building block molecules. The individual opportunities were evaluated based on their technical difficulty, market, market risk, building block utility, and whether a pure material or a mixture would be produced. Unlike the “Sugars Top 10” report it was difficult to identify the ten best opportunities, however, the potential opportunities fell nicely into near-, medium- and long-term opportunities. Furthermore, the near-, medium- and long-term opportunities roughly align with the three “product types.” From this analysis a list of technical barriers was developed which can be used to identify research needs. Lignin presents ...
Date: October 1, 2007
Creator: Holladay, John E.; White, James F.; Bozell, Joseph J. & Johnson, David
Partner: UNT Libraries Government Documents Department

The Path of Carbon in Photosynthesis. XXI. The Cyclic Regenerationof Carbon Dioxide Acceptor

Description: Photosynthesizing plants have been exposed to C{sup 14}O{sub 2} for short periods of time (0.4 to 15 sec.) and the products of carbon dioxide reduction analyzed by paper chromatography and radio autography. Methods have been developed for the degradation of ribulose and sedoheptulose. These sugars, obtained as their phosphate esters from the above C{sup 14}O{sub 2} exposures and from other experiments, have been degraded and their distribution of radiocarbon determined. The distribution of radiocarbon in these sugars, and other data, indicate that sedoheptulose phosphate and ribulose diphosphates are formed during photosynthesis from triose and hexose phosphates, the latter being synthesized, in turn, by the reduction of 3-phosphoglyceric acid.
Date: October 1, 1953
Creator: Bassham, J.A.; Benson, A.A.; Kay, Lorel D.; Harris, Anne Z.; Wilson, A.T. & Calvin, M.
Partner: UNT Libraries Government Documents Department

Continuous Ethanol Production Using Immobilized-Cell/Enzyme Biocatalysts in Fluidized-Bed Bioreactor (FBR)

Description: The immobilized-cell fluidized-bed bioreactor (FBR) was developed at Oak Ridge National Laboratory (ORNL). Previous studies at ORNL using immobilized Zymomonas mobilis in FBR at both laboratory and demonstration scale (4-in-ID by 20-ft-tall) have shown that the system was more than 50 times as productive as industrial benchmarks (batch and fed-batch free cell fermentations for ethanol production from glucose). Economic analysis showed that a continuous process employing the FBR technology to produce ethanol from corn-derived glucose would offer savings of three to six cents per gallon of ethanol compared to a typical batch process. The application of the FBR technology for ethanol production was extended to investigate more complex feedstocks, which included starch and lignocellulosic-derived mixed sugars. Economic analysis and mathematical modeling of the reactor were included in the investigation. This report summarizes the results of these extensive studies.
Date: November 16, 2003
Creator: Nghiem, NP
Partner: UNT Libraries Government Documents Department

Formation and Human Risk of Carcinogenic Heterocyclic Amines Formed from Natural Precursors in Meat

Description: A group of heterocyclic amines that are mutagens and rodent carcinogens form when meat is cooked to medium and well-done states. The precursors of these compounds are natural meat components: creatinine, amino acids and sugars. Defined model systems of dry-heated precursors mimic the amounts and proportions of heterocyclic amines found in meat. Results from model systems and cooking experiments suggest ways to reduce their formation and, thus, to reduce human intake. Human cancer epidemiology studies related to consumption of well-done meat products are listed and compared.
Date: November 22, 2004
Creator: Knize, M G & Felton, J S
Partner: UNT Libraries Government Documents Department

Fueling the Future with Fungal Genomics

Description: Fungi play important roles across the range of current and future biofuel production processes. From crop/feedstock health to plant biomass saccharification, enzyme production to bioprocesses for producing ethanol, higher alcohols or future hydrocarbon biofuels, fungi are involved. Research and development are underway to understand the underlying biological processes and improve them to make bioenergy production efficient on an industrial scale. Genomics is the foundation of the systems biology approach that is being used to accelerate the research and development efforts across the spectrum of topic areas that impact biofuels production. In this review, we discuss past, current and future advances made possible by genomic analyses of the fungi that impact plant/feedstock health, degradation of lignocellulosic biomass and fermentation of sugars to ethanol, hydrocarbon biofuels and renewable chemicals.
Date: April 29, 2011
Creator: Grigoriev, Igor V.; Cullen, Daniel; Hibbett, David; Goodwin, Stephen B.; Jeffries, Thomas W.; Kubicek, Christian P. et al.
Partner: UNT Libraries Government Documents Department

Genome analysis of Elusimicrobium minutum, the first cultivated representative of the Elusimicrobia phylum (formerly Termite Group 1)

Description: The candidate phylum Termite group 1 (TG1), is regularly 1 encountered in termite hindguts but is present also in many other habitats. Here we report the complete genome sequence (1.64 Mbp) of Elusimicrobium minutum strain Pei191{sup T}, the first cultured representative of the TG1 phylum. We reconstructed the metabolism of this strictly anaerobic bacterium isolated from a beetle larva gut and discuss the findings in light of physiological data. E. minutum has all genes required for uptake and fermentation of sugars via the Embden-Meyerhof pathway, including several hydrogenases, and an unusual peptide degradation pathway comprising transamination reactions and leading to the formation of alanine, which is excreted in substantial amounts. The presence of genes encoding lipopolysaccharide biosynthesis and the presence of a pathway for peptidoglycan formation are consistent with ultrastructural evidence of a Gram-negative cell envelope. Even though electron micrographs showed no cell appendages, the genome encodes many genes putatively involved in pilus assembly. We assigned some to a type II secretion system, but the function of 60 pilE-like genes remains unknown. Numerous genes with hypothetical functions, e.g., polyketide synthesis, non-ribosomal peptide synthesis, antibiotic transport, and oxygen stress protection, indicate the presence of hitherto undiscovered physiological traits. Comparative analysis of 22 concatenated single-copy marker genes corroborated the status of Elusimicrobia (formerly TG1) as a separate phylum in the bacterial domain, which was so far based only on 16S rRNA sequence analysis.
Date: February 1, 2009
Creator: Herlemann, D. P. R.; Geissinger, O.; Ikeda-Ohtsubo, W.; Kunin, V.; Sun, H.; Lapidus, A. et al.
Partner: UNT Libraries Government Documents Department

Ripeness sensor development. Final report of a Phase 2 study

Description: This is a final report for the Phase II study entitled ``Ripeness Sensor Development.`` The overall objective of the study was the development of a prototype device capable of testing whole fruits for sugar content. Although ripeness and sugar content are not synonymous, they are closely related. Furthermore, the consumer`s acceptance of or preference for fruits is strongly influenced by sugar content. Therefore, the device was called a ripeness sensor. The principle behind the measurement is proton magnetic resonance ({sup 1}H-MR). For several decades, chemists, pharmacists and other scientists have been using {sup 1}H-MR to investigate chemical structure and composition. More recently, the technique has been used in laboratories of the food industry for quality control. This effort represents one of the first attempts to adapt {sup 1}H-MR to use in a commercial facility. 28 refs., 36 figs., 7 tabs.
Date: August 1, 1995
Creator: Stroshine, R.
Partner: UNT Libraries Government Documents Department

Optimizing cellulase mixtures for maximum rate and extent of hydrolysis. Final report

Description: Pure Thomomonospora fusca and Trichoderma reesei cellulases and their mixtures were studied to determine the optimal set of cellulases for biomass hydrolysis. The objective was to reduce the cost of cellulase in order to help lower the overall processing cost of the enzymatic conversion of biomass cellulose to sugars, which can then be fermented into fuels and other energy-intensive chemicals. No cellulase mixture was obtained that was much better than the best commercially available preparations. However, the study has greatly increased knowledge of T. fusca cellulases, synergism, and cellulose binding, and provide evidence that future work will produce cellulases with higher activity in degrading crystalline cellulose. T. fusca cellulases may have good industrial potential because: (1) they are compatible with industrial processes that operate at elevated temperatures; (2) they retain 90% of their activity under neutral or basic conditions, which provides a great deal of flexibility in reactor design and operation; and (3) tools are now available to change specific amino acid residues in their catalytic domains and to assess how these changes influence catalysis. 74 refs.
Date: March 1, 1997
Creator: Walker, L.P. & Wilson, D.B.
Partner: UNT Libraries Government Documents Department

Modeling scaleup effects on a small pilot-scale fluidized-bed reactor for fuel ethanol production

Description: Domestic ethanol use and production are presently undergoing significant increases along with planning and construction of new production facilities. Significant efforts are ongoing to reduce ethanol production costs by investigating new inexpensive feedstocks (woody biomass) and by reducing capital and energy costs through process improvements. A key element in the development of advanced bioreactor systems capable of very high conversion rates is the retention of high biocatalyst concentrations within the bioreactor and a reaction environment that ensures intimate contact between substrate and biocatalyst. One very effective method is to use an immobilized biocatalyst that can be placed into a reaction environment that provides effective mass transport, such as a fluidized bed. Mathematical descriptions are needed based on fundamental principles and accepted correlations that describe important physical phenomena. We describe refinements and semi-quantitatively extend the predictive model of Petersen and Davison to a multiphase fluidized-bed reactor (FBR) that was scaled-up for ethanol production. Axial concentration profiles were evaluated by solving coupled differential equations for glucose and carbon dioxide. The pilot-scale FBR (2 to 5 m tall, 10.2-cm ID, and 23,000 L month{sup -1} capacity) was scaled up from bench-scale reactors (91 to 224 cm long, 2.54 to 3.81 cm ID, and 400 to 2,300 L month{sup -1} capacity). Significant improvements in volumetric productivites (50 to 200 g EtOH h{sup -1} L{sup -1} compared with 40 to 110 for bench-scale experiments and 2 to 10 for reported industrial benchmarks) and good operability were demonstrated.
Date: September 1995
Creator: Webb, O. F.; Davison, B. H. & Scott, T. C.
Partner: UNT Libraries Government Documents Department