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  • 1
    Electronic Resource
    Electronic Resource
    Acetylation of cellulose I and II studied by limiting viscosity and X-ray diffractionPaper presented in part at 153rd meeting of the American Chemical Society in Miami, Florida, April, 1967. (1968)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 6 (1968), S. 745-773 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When cellulose triacetates and some hydrolyzed acetates are boiled in 2.5N hydrochloric acid there is no residue. Under the same conditions cellulose is hydrolyzed, and a residue is obtained with a limiting viscosity that is related to the average length of the cellulose crystallites. These findings are combined to develop a method for studying the progress of acetylation through the amorphous portion of cellulose and into the crystallites, and to investigate the relative reactivities of cellulose I and cellulose II. Acetates were made from cotton and wood cellulose by a “fibrous” (heterogeneous) esterification involving sulfoacetic acid or perchloric acid catalyst in acetic acid-acetic anhydride; the final acetyl contents (10-41%) were attained by stopping the reaction at various points short of the triester (rather than by hydrolyzing a triester). When these acetates were boiled in 2.5N HCI they did not disappear completely, and the residues were cellulose I, indicating that cellulose acetate had been removed. With increasing acetyl the yield of residue decreased, and beyond about 33% acetyl the viscosity and x-ray measurements showed that the length and width of the crystallites decreased. However, when a nonsolvent such as toluene was added to the acetylation medium, the limiting viscosity did not change over the same acetyl range (up to 40%). Samples of varying acetyl values were taken during a regular acetylation of cotton linters in a mixer with sulfuric acid catalyst. X-ray studies of the residues obtained by boiling the acetates in 2.5N HCI revealed the presence of unreacted cellulose I even after 40% acetyl had been reached. This explains why the manufacture of cellulose esters from cellulose I requires complete esterification before they are hydrolyzed to the desired acetyl level. It was shown that there is a distinct difference between the acetylation reactivity of cellulose I and cellulose II. This indicates the importance of avoiding cellulose II formation during the refinement of cellulose for the manufacture of cellulose acetate in a process involving activation with acetic acid.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1968.160060410
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  • 2
    Electronic Resource
    Electronic Resource
    Measurement of oxygen solubility in fermentation media: A colorimetric method (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 578-583 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods of measuring oxygen solubility in culture media are scarce, and those available are tedious to apply. A simple colorimetric assay was developed and applied to the analysis of oxygen solubility during alcoholic fermentation. The method was based on the consumption of oxygen by glucose oxidase activity and the production of the pink quinone of syringaldazine by coupled peroxidase activity. Color formation at 526 nm progressed through an optimum that was a linear function of the oxygen added to the assay. Sensitivity was maximized by operating at pH 7 and limiting the medium sample volume added. Each assay took 10-15 min to prepare and react. Reaction time was minimized by using abundant glucose and enzyme concentrations. Data obtained by the assay developed showed good agreement with published oxygen solubilities in water and selected media at various temperatures. Subsequent analyses of fermentation broths indicated falling sugar concentration to be primarily responsible for increases in oxygen solubility during fermentation. For example, during fermentations started with 230 g/L xylose or glucose, oxygen solubility could increase by 41% due to sugar consumption alone. This procedure can provide the solubility data needed to accurately calibrate in-line electronic probes for monitoring dissolved oxygen concentration during fermentation processes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260330510
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of polyaryloxyphosphazenes (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 433-444 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis, dilute solution characterization, and thermal analysis of seven polyaryloxyphosphazenes are described. Synthesis is accomplished by the ring-opening polymerization of hexachlorocyclotriphosphazene at 245°C, followed by reaction of polydichlorophosphazene with sodium aryloxide salts in solution at 115°C. Polymers prepared and characterized have the general structure [(ArO)2PN]n, with Ar = C6H5, m- and p-CH3C6H4, m- and p-ClC6H4, p-C2H5C6H4, or p-CH3OC6H4. Elemental and infrared analyses show these polymers are essentially free of reactive chlorine sites. All the polymers displayed high intrinsic viscosities [η] 〉 1 dl/g, in tetrahydrofuran or chloroform. Closer examination of the dilute solution properties of two polyaryloxyphosphazenes revealed high molecular weights (M̄w〉 6 × 105) and broad molecular weight distributions (M̄w/M̄n 〉 4.7). The experimental values for the Z-average radii of gyration, 〈S2〉z1/2, characterized at near theta conditions, are larger than the calculated values for a freely rotating chain, which suggests that these polymers are relatively linear and not highly branched. Thermal analysis revealed second-order glass transitions between -37 and +13°C and first-order endothermic transitions between 43 and 160°C for the different polymers. Although crystalline structure can persist above this first-order transition, this temperature can be regarded as a melting temperature or softening temperature at which films can be molded. Decomposition temperatures, measured in argon and oxygen, ranged from 250°C to 400°C.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120214
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  • 4
    Electronic Resource
    Electronic Resource
    Clinical-size dextran by direct fermentation (with NRRL B-1351 Streptococcus sp.)This study was supported in part by grant 4395 from the Surgeon General's Office, U.S. Department of Defence. The views or conclusions contained in this paper are not to be construed as necessarily reflecting the views or endorsement of the Department of Defence. (1960)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Biochemical and Microbiological Technology and Engineering 2 (1960), S. 381-399 
    Details
    ISSN: 0368-1467
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dextran, a polymer of glucose, has been widely used as a blood-plasma volume expander. In whole culture fermentations most dextran-producing organisms elaborate dextrans that have molecular weights of many millions and must be depolymerized and fractionated to obtain a product suitable for clinical use. An exception however is Streptococcus sp. (Strain DS-50) NRRL B-1351. In the work described here, this organism is used to produce clinical-size dextran in high yields, both on a laboratory- and a pilot-plant scale. With this process, fractionation is required but depolymerization is not. Fermentations of media containing 15 per cent sucrose are complete in less than 48 hours with 0·2 per cent inoculum. Yields of native dextran and clinical-size dextran by methanol precipitation are 68 and 43 per cent of the theory, respectively. The structurally heterogeneous dextran formed by NRRL B-1351 has a higher viscosity for a given molecular weight than does NRRL B-512 dextran. The viscosity-molecular weight relationship for the former may be expressed by the equation [η] = 6·51 × 10-4Mw0·554. The high-molecular weight fraction had approximately 75 per cent of 1,6-like linkages, as compared with 87 per cent for the clinical fraction. All fractions had a lower ratio of 1,6 to non-1,6 linkages than did NRRL B-512 dextrans.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbmte.390020402
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  • 5
    Electronic Resource
    Electronic Resource
    Equipment for cultivation of fastidious micro-organisms (1959)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Biochemical and Microbiological Technology and Engineering 1 (1959), S. 27-36 
    Details
    ISSN: 0368-1467
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Equipment has been developed in which fermentation processes for fastidious, pathogenic micro-organisms can be operated on a pilot-plant scale. Experience has shown the need for the development of concepts, techniques, and equipment meeting more stringent requirements than those ordinarily encountered in the fermentation industry. A system has been developed for the preparation of pure cultures which may be used either for the development of processes or in the preparation of substantial quantities of pure cultures. The equipment includes specially designed valves, fermentors, piping arrangement, and requires special methods of operation in order to maintain pure cultures during growth of the organism. The number of cultures of pathogenic, fastidious micro-organisms contaminated in the systems commonly used in industry is materially greater than the number of contaminated cultures produced in the system described.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbmte.390010104
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  • 6
    Electronic Resource
    Electronic Resource
    Dielectric properties of polystyrene and some polychlorostyrenes from 4°K to room temperature (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 7 (1969), S. 1721-1733 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric measurements of carefully purified specimens of polystyrene and poly(2,3,4 or 3,4-chlorostyrene) have been obtained at audio frequencies ranging from 0.1 to 20 kHz and at temperatures between 4 and 300°K. Each of the samples exhibits a dielectric loss maximum in the range 15-50°K. The temperature of the maximum loss decreases with the addition of a substituent which lowers the symmetry of the pendant phenyl group. The results are explained by a model which invokes a coupling mechanism between two distinct modes of side group motions. This same model also explains some results of previously reported measurements of mechanical losses in similar polymers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.160071008
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  • 7
    Electronic Resource
    Electronic Resource
    Raw materials evaluation and process development studies for conversion of biomass to sugars and ethanolThis paper was prepared for presentation at the Second Annual Symposium on Fuels from Biomass, Rensselaer Polytechnic Institute, Troy, New York, 20-22 June 1978. This work was done with support from the Department of Energy. Any conclusions or opinions expressed in this report represent solely those of the author(s) and not necessarily those of the Lawrence Berkeley Laboratory nor of the Department of Energy. (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 163-183 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A range of cellulosic raw materials in the form of agricultural crop residue was analyzed for chemical composition and assessed for potential yields of sugars through chemical pretreatment and enzymatic hydrolysis of these materials. Corn stover was used as a representative raw material for a preliminary process design and economic assessment of the production of sugars and ethanol. With the process as presently developed, 24 gal ethanol can be obtained per ton of corn stover at a processing cost of about $1.80/gal exclusive of by-product credits. The analysis shows the cost of ethanol to be highly dependent upon: (1) the cost of the biomass, (2) the extent of conversion to glucose, (3) enzyme recovery and production cost, and (4) potential utilization of xylose. Significant cost reduction appears possible through further research in these directions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260230111
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  • 8
    Electronic Resource
    Electronic Resource
    Production of sugars from wood using high-pressure hydrogen chloride (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 2757-2773 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Saturating wood particles with HCl gas under pressure was found to be an effective pretreatment prior to subjecting wood to dilute acid hydrolysis. Pretreament is necessary to release sugars from wood because of the tight lattice structure of cellulose. The HCl gas makes the cellulose more susceptible to subsequent acid hydrolysis and the glucose yield is doubled when dilute acid hydrolysis is preceded by HCl saturation at high pressure. The saturation was most effectively performed in a fluidized bed reactor, with pure HCl gas fluidizing an equal volume of ground wood plus inert particles. The fluidized bed effectively dissipated the large amount of heat released upon HCl absorption into the wood. Batch reaction times of 1 h at 315 psia gave glucose yields of 80° and xylose yields of 95° after dilute acid hydrolysis. A model was developed which proposed gas diffusing through the solid as limiting the reaction rate and this was found to effectively describe the HCl-wood reaction in the fluidized bed. The HCl was found to form a stable adduct with the lignin residue in the wood, in a ratio of 3.33 mole of lignin monomer. The adduct was broken upon the addition of water.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260251117
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  • 9
    Electronic Resource
    Electronic Resource
    Optimum ph and temperature conditions for xylose fermentation by Pichia stipitis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 727-731 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pichia stipitis NRRL Y-7124 is a xylose-fermenting yeast able to accumulate ca. 57 g/L ethanol. Because optimum process conditions are important, data were collected to determine the effects of temperature and pH on growth and fermentation rates and product accumulations. Temperatures (26-35°C) providing optimum biomass and ethanol productivities did not necessarily provide maximum ethanol accumulation. Xylitol and residual xylose concentrations increased with temperature. Maximum ethanol selectivity was achieved at 25-26°C with minimal sacrifice to production rates. The temperature optimum for xylose could not be generalized to glucose fermentations, in which ethanol productivity and accumulation were optimum at 34°C. The optimum pH range for growth and fermentation on xylose was 4-7 at 25°C.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350710
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  • 10
    Electronic Resource
    Electronic Resource
    Growth, death, and oxygen uptake kinetics of Pichia stipitis on xylose (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 973-980 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pichia stipitis NRRL Y-7124 has potential application in the fermentation of xylose-rich waste streams, produced by wood hydrolysis. Kinetic models of cell growth, death, and oxygen uptake were investigated in batch and oxygen-limited continuous cultures fed a rich synthetic medium. Variables included rates of dilution (D) and oxygen transfer (K1a) and concentrations of xylose (X), ethanol (E), and dissolved oxygen (Cox). Sustained cell growth required the presence of oxygen. Given excess xylose, specific growth rate (μ) was a Monod function of Cox. Specific oxygen uptake rate was proportional to μ by a yield coefficient relating biomass production to oxygen consumption; but oxygen uptake for maintenance was negligible. Thus steady-state COX depended only on D, while steady-state biomass concentration was controlled by both D and K1a. Given excess oxygen, cells grew subject to Monod limitation by xylose, which became inhibitory above 40 g/L. Ethanol inhibition was consistent with Luong's model, and 64. 3 g/L was the maximum ethanol concentration allowing growth. Actively growing cells died at a rate that was 20% of μ. The dying portion increased with E and X.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260371012
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