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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Utilization of extracted hardwood flakes for manufacturing oriented strand lumber

McConnell, Thomas Eric 10 December 2010 (has links)
Lignocellulosic ethanol production currently uses expensive and harsh methods to extract wood sugars from small-diameter hardwood trees that otherwise would have little or no marketability. A byproduct that adds no value to the conversion process results, thus alternative methods are needed to make this fuel source cost-effective. This dissertation proposes only partially hydrolyzing southern hardwoods, extracting some polysaccharides for ethanol fermentation while leaving behind a modified wood material which could be used as furnish for manufacturing strand-based wood composites. Three treating solutions, 1% sulfuric acid, water, and 1% sodium hydroxide, along with untreated controls, were utilized in a partial hydrolysis at 150°C for 30 minutes. The treatments’ effects were measured by testing the mechanical, physical, surface, and durability properties of red oak, sweetgum, and yellow-poplar miniature beams (3 mm x 15 mm x 150 mm, t x r x l). These properties were then correlated to the polysaccharide content of the modified woods following treatment. All treatments provided a significant mass loss, with sweetgum’s mass loss being significantly greater than the other species. The initial effect of the partial hydrolysis on modulus of elasticity (MOE) showed water reduced MOE the least for each species. Sweetgum produced a higher reduction in MOE in all three solutions. Specific modulus was calculated to eliminate the density effect between the treatment combinations for measuring bending properties at oven-dry conditions. Sweetgum produced a lower SM in all treatments, and only the water treatment consistently reduced SM across all species. Wettablility was measured by dynamic contact angle analysis via the Wilhelmy plate technique in four probe liquids. Surface energies were then calculated by the geometric mean procedure. Acid and water treatments improved the wettability for all species. Alkaline treatment effects were species-specific. All treatments improved the surface energy of red oak. The AWPA E1-09 no-choice termite test determined mass loss due to Reticulitermes flavipes Kollar. Yellow-poplar averaged a significantly higher mass loss while wood treated in water or NaOH showed a higher degree of termite degradation compared to the controls. Polysaccharide content significantly correlated with mass loss due to treatment and specific modulus.
2

Produkce hydrolyzátů bramborových bílkovin pomocí vybraných potravinářských proteas / Production of potato protein hydrolysates using selected proteases applicable for food industry

BRABCOVÁ, Anna January 2016 (has links)
Partial hydrolysates of two types potato protein concentrates were produced by four selected food proteases. Commercialy produced (company Lyckeby) protein concentrate and laboratory prepared concentrate from tubers of Ornella cultivar were subjected of enzymatic hydrolysis by Fromase 220TL, Fromase 220XLG, Maxiren XDS (commercialy available forms of chymosin) and Neutral protases from bacterial Bacillus subtilis. Protein profile of hydrolysates was created using SDS-PAGE. All hydrolysates were determined by solubility and antioxidant activity using DPPH method. The main aim of this study was to evaluate the efficiency of digestion potato protein concentrate by these selected proteases. Based on the results, the most effective enzyme used for hydrolysis of PC was Neutral proteases form Bacillus subtilis.

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