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Sanchez, Gil Yaritza M. "Characterization and rheological properties of Camelina sativa gum: interactions with xanthan gum, guar gum, and locust bean gum." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/32789.
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Master of ScienceDepartment of Biological & Agricultural Engineering
Donghai Wang
Gums are water-soluble polysaccharides used in many industrial and food applications because of their functions such as thickening, gelling, emulsification, adhesion, and encapsulation. Interactions between gums are conducted to enhance functional properties of finished products and reduce processing costs. In this study, camelina gum, from the oil-seed plant Camelina sativa, is characterized by carbohydrate composition and morphological, thermal, and rheological properties. Interactions with xanthan gum, galactomannans guar gum, and locust bean gum (LBG) are also studied. Camelina gum is composed of arabinose, rhamnose, galactose, glucose, xylose and mannose; according to high-performance anion exchange chromatography analysis. Scanning electron microscopy and transmission electron microscopy images showed camelina gum with fibrillar structure and intermeshed network. Camelina gum solutions exhibited a shear thinning flow behavior in a range of concentrations (0.1% to 2.0% w/w) and shear rate (0.001 sˉ¹ to 3000 sˉ¹). Camelina gum is temperature independent at temperature ranges from 4 °C to 90 °C. The apparent viscosity increased as gum concentration increased. Mechanical properties of camelina gum demonstrated viscoelastic behavior with entangled molecular chains. Interaction of camelina gum with monovalent salt NaCl significantly reduced the viscosity of camelina gum solution at 1% when NaCl concentration increased. Camelina gum is soluble in water up to 60% ethanol content, in which the rheological properties do not significantly differ from camelina gum in water solution only. A synergy with xanthan and galactomannans was determined. All mixtures exhibited shear-thinning flow behavior, solid-like behavior at low frequencies, and liquid-like behavior at high frequencies. For camelina-galactomannans mixtures, synergistic interactions occurred in LBG-camelina mixtures at ratios of 1:1 and 3:1. For xanthan-camelina mixture, maximum synergy was observed at the ratio 1:1. Synergistic effects of gum mixtures suggest dependency on the ratios and chemical structures of the gums. The effect of temperature on apparent viscosity of mixtures is not significant. Results showed that camelina gum can be used for commercial applications.
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McGovern-Traa, Caroline. "Studies on gellan gum." Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/15337.
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The composition of gellan gum elaborated by wild type Sphingomonas paucimobilis was studied. Gas chromatographic methods of analysis were compared. Analysis of neutral sugars was carried out by Saemen hydrolysis and Stones method. Stones method was preferred due to its simplicity and the production of comparable results to those obtained following Saemen hydrolysis. The neutral sugars of gellan gum were analysed by GC/MS following preparation of per-methylated alditol acetates (PMAAs). Two methods were used for making alditol acetates, the Hakamori and sodium hydroxide (NaOH) methods. Although the NaOH method was simpler and faster to carry out, the results were not representative of the true composition of gellan gum. The Hakamori method revealed the presence of 33%, 1,4 rha, 30% 1,3 glc and 31% 1,4 glc in agreement with the sugar compositions of O'Neill et al. (1983) and Jansson et al. (1983) who elucidated the structure of gellan gum simultaneously. To determine the glucuronic acid content of gellan gum, samples were carboxy-reduced prior to analysis. Two methods were compared, the lithium aluminium deuteride and tetrahydrofuran (THF) methods. The THF method revealed the presence of 24%, 1, 4 rha, 24% 1,3 glc 26% 1,4 glc and 25% 1,4, 6 glc (corresponding to glcA). Physiological studies were carried out with twenty mutant strains of S. paucimobilis in batch culture. The chemical composition, viscosity, gelation and rheological properties of EPS produced from many of these strains were further investigated. Some of the strains elaborated polysaccharide, named fine precipitate, which differed chemically from gellan gum. Rheological measurements were carried out on several EPS samples using a mechanical rheometer. Large differences in gel strength were detected.
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Liu, Claire Ann. "An investigation into the gel characteristics of xanthan gum locust bean gum mixes." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251853.
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Pieri, Celina de. "Expressão, purificação e caracterização das enzimas Gum D e Gum C envolvidas na biossíntese do exopolissacarídeo produzido pela bactéria Xylella fastidiosa." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-18112013-115231/.
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A Clorose Variegada de Citrus (CVC) é uma doença que vem atingindo grandes plantações de laranjas no Brasil e outros países como Estados Unidos, França e Espanha. O principal efeito da doença é o surgimento de manchas amarelas nas folhas que progridem para toda a extensão levando-a à necrose. Os frutos são pequenos, apresentam casca dura, sendo impróprios para o consumo. O agente causador da CVC é a bactéria Xylella fastidiosa que é limitada ao xilema. A bactéria é transmitida por insetos conhecidos como \"cigarrinhas\" que se alimentam na seiva do xilema. Esta bactéria apresenta em seu genoma um Operon contendo 9 genes (B,C,D,E,F,H,J,K,M) responsáveis pela biossíntese do exopolissacarídeo denominado goma fastidiana, que pode estar envolvido na sua patogenicidade. No presente trabalho, realizou-se estudos com as enzimas GumD (uma enzima glicosiltransferase I que faz a primeira adição de glicose-l-fosfato ao lipídeo prenol) e GumC (que provavelmente está envolvida na etapa de polimerização e/ou secreção do polissacarídeo formado através da membrana da bactéria), com o objetivo de contribuir para melhor entendimento da via biossintética. O gene gumD, que codifica a enzima GumD, foi clonado nos vetores de expressão pMAL¬c2x e pKK223-3. A proteína GumD foi purificada através das cromatografias de troca aniônica e filtração a gel. O peso molecular e o pI da enzima foram determinados usando respectivamente a técnica de filtração a gel e o sistema Fast de eletroforese. A enzima foi caracterizada quanto ao seu enovelamento através da técnica de Dicroísmo Circular, apresentando um espectro característico de estrutura secundária enovelada, composta predominantemente por a-hélices. O gene gumC, que codifica para a proteína GumC, foi clonado nos vetores de expressão pMAL-c2x (no qual a enzima é expressa em fusão com a proteína MBP - Maltose Binding Protein) e pET29a (a proteína é expressa sem fusão). A proteína em fusão GumC-MBP foi parcialmente pura através da coluna de amilose e foi caracterizada através da técnica de Imunoblotting. A enzima GumC expressa no vetor pET29a está em fase de purificação. Anticorpos anti-GumC-MBP foram produzidos em camundongos e serão utilizados como uma forma de caracterizar a proteína GumC expressa sem fusão. Estudos estruturais destas enzimas poderão trazer informações fundamentais para o conhecimento da via biossintética, assim como para o desenvolvimento de inibidores específicosThe Citrus Variegated Chlorosis (CVC) is a serious disease of orange trees in countries like Brazil, USA, France and Spain. Typical disease symptoms include conspicuous variegations with chlorotic areas on the upper side and small necrotic lesions on the lower side of the leaves. The affected fruits are smaller, hardened and without commercial value. Citrus variegated chlorosis is caused by Xylella fastidiosa, which is a xylem-limited bacterium. X fastidiosa is transmitted by specific sharpshooter leafhoppers when the insect feeds on the xylem sap. X fastidiosa has a nine-gene operon (B, C, D, E, F, H, J, K, and M genes) responsible for the biosynthesis of exopolysaccharides, denoted fastidian gum, which can be involved in its pathogenicity. GumD glycosyltransferase enzyme adds the first sugar, glycose-l-phosphate, to the prenol lipid. GumC enzyme probably is involved in the polymerization and/or exportation of the fastidian gum through the membrane of the bacterium. Studies were done on the GumD and GumC enzymes with the aim of getting a better understanding of the exopolysaccharide biosynthetic pathway. The gumD gene was cloned into the pMAL-c2x and pKK223-3 expression vectors, and GumD protein was purified through ion exchange and size exclusion chromatography. Then GumD molecular mass and pl were determined using, respectively, size exclusion chromatography and electrophoresis. In addition, according to circular dichroism spectroscopy, GumD prevalent secondary structure is u-helix. On the other hand, the gumC gene was cloned in two expression vectors: pMAL-c2x (the protein is expressed in fusion with Maltose Binding Protein ¬MBP) and pET29a (the protein is expressed without fusion in our strategy). GumC¬MBP, the protein in fusion, was partially purified using an amylose column and the fusion between GumC and MBP was confirmed with imunoblotting technique. Purification trials of GumC enzyme expressed in pET29a are in course. Anti-GumC¬MBP antibodies were already produced in mice and they will be used to characterize the GumC protein expression without fusion. Structural studies of GumD and GumC enzymes will provide information about the fastidian gum biosynthetic pathway, as well as to the development of specific inhibitors
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Gothard, Michelle Gina Elizabeth. "Functional properties of gellan gum." Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426116.
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Talling, Russell James. "Deformation mechanism of gum metal." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497950.
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Gum metal (Ti-36Nb-2Ta-3Zr-0.3O) is a recently developed multifunctional bcc titanium alloy that exhibits high strength, high ductility and high yield strain. The ideal strength (Tmax) of Gum metal is suggested to be comparable with the actual strength, implying that deformation can occur via ideal shear without any dislocation activity. Calculations indicate that C approaches zero when the average ela value is around 4.24 in Ti-X binary alloys, li is suggested that this is attained in Gum metal, whose e/a is 4.24. The effect of processing route and chemical composition on the deformation mechanisms and mechanical properties of Gum metal were also investigated. ed. A more cost effective processing route involving ingot metallurgy was trialled and the mechanical properties were comparable to the alloys produced via powder metallurgy.
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McDougal, Fiona Janet. "Studies on gum exudates, with particular reference to gum Arabic (Acacia senegal) and other Acacia species." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/11112.
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Kruptseva, N. D. "Chewing gum- 5000 years of history." Thesis, Sumy State University, 2014. http://essuir.sumdu.edu.ua/handle/123456789/45611.
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Chewing gum is a soft, cohesive substance intended for chewing but not swallowing. Humans have used chewing gum for at least 5,000 years.
Chewing gum in various forms has existed since the Neolithic period. 5,000-year-old chewing gum made from bark tar, with tooth imprints, has been found in Kierikki, Yli-Ii, Finland.
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Trudova, Evgenia. "Xanthan Gum : Fermentation of Xanthomonas Campestris." Thesis, Malmö universitet, Fakulteten för hälsa och samhälle (HS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-18694.
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Xanthan gum is one of the most common thickening agents used worldwide.The industrial manufacturing process of xanthan gum uses cheap, carbohydrate rich mediums for fermentation of the bacterium Xanthomonas campestris. The objective of this study was to compare different fermentation mediums based on grain powder for small scale fermentation of Xanthomonas campestris. Culture mediums containing wheat or cornstarch and the less allergen prone medium containing potato starch and oat flour were investigated. All four fermentation mediums of this study showed signs of thickening, indicating the presence of alive and growing Xanthamonas campetris. Based on the growth on MacConkey and NA-agar plates, all four fermentation products showed the presence of bacteria. The fermentation product from a culture medium containing both potato starch and oat flour showed a higher concentration of bacteria compared to a culture medium containing wheat flour or cornstarch. The fermentation product in the presence of oat flour showed more than 100 times higher bacterial concentration in the fermentation product compared to wheat flour. Data suggests that potato starch and oat flour fermentation performed better than wheat flour and cornstarch and these less allergen prone mediums can be used as an alternative for fermentation of Xanthamonas campetris in the production of xanthan gum.Xantangummi är ett av de vanligast förkommande förtjockningsmedlen som används i världen.I den industriella tillverkningsprocessen av xantangummi används billiga, kolhydratrika medier för fermentering av bakterien Xanthomonas campestris. Syftet med denna studie var att jämföra olika fermenteringsmedier innehållande vetemjöl, majsstärkelse, potatisstärkelse, och havremjöl för småskalig fermentation av Xanthomonas campestris. Alla fyra fermentationsmedierna som användes i denna studie visade tecken på förtjockning, vilket indikerar närvaron av levande och växande Xanthamonas campetris. Baserat på tillväxten på MacConkey- och NA-agarplattor visade alla fyra fermenteringprodukterna närvaron av bakterium. Fermenteringsprodukten från odling i mediums innehållande både potatisstärkelse och havremjöl uppvisade en högre koncentration av bakterier jämfört med odlingsmedium innehållande vetemjöl eller majsstärkelse. Fermenteringprodukten i närvaro av havremjöl visade en mer än 100 gånger högre bakteriekoncentration jämfört med vetemjöl. Data tyder på att fermentering med potatisstärkelse och havremjöl ger bättre tillväxt än medium innehållande vetemjöl och majsstärkelse och att mindre allergenbenägna medium kan användas som alternativ för fermentering av Xanthamonas campetris vid produktion av xantangummi.
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Bridgeman, Myrtle Mildred Esprit. "Analytical studies of plant gum exudates." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/27268.
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The gum exudate from Acacia calcigera, a species recently discovered in Australia, has been shown to have a highly positive specific rotation and high molecular weight with a low rhamnose content. These results are characteristic of species within the Sec?tion Gummiferae, a predominantly African section of the genus Acacia. Analytical data for the gum exudate from a cultivar of Leucaena leucocephala from India and for gum arabic (Acacia senega!) fromAfrica were compared. The Leucaena gum had a chemical composition and properties sim ilar to gum arabic but was of higher viscosity and molecular weight; these differences could be commercially important if gum collection from Leucaena could be organised. in a series of studies in laboratory rats, gum arabic was com?pletely degraded on incorporation into a standard rat diet at levels of 2g/day/rat and 4g/day/rat. On incorporation into an elemental, low residue diet ( ?Flexical1) gum arabic was partially degraded when fed to rats at 2g/day/rat but was found to be degraded more exten?sively if fed at a reduced level (lg/day/rat). Gum arabic, mixed with faeces from rats fed the elemental diet was partially degraded by faecal bacteria. The different results obtained when gum arabic was incorporated into two different diets indicated the importance of choice of type of diet and dose level used in dietary studies. VFaecal extracts obtained from rats fed a standard diet supple?mented with gum karaya (1.2g/day/rat) were shown to be similar, but not identical, to gum karaya that had been mixed with faeces then re-extracted. A similar result was obtained when an elemental diet was used. It was not possible to conclude whether or not the gum karaya extracted from test faeces had been degraded because of the difficulties found to be associated with attempted molecular weight measurements of the impure forms of the gum extracted. Seven commercial gum tragacanth samples from Iran were found to vary in composition and in viscosity and in the ratio of their water-insoluble and water-soluble components. Their amino acid con?tents did not differ extensively. Five commercial gum tragacanth samples from Turkey showed less variation than the Iranian samples; although having lower viscosity, their amino acid compositions were sim ilar to those of the Iranian samples. A Turkish gum tragacanth sample from Astragalus microcephalus (the major source of the gum) differed extensively analytically from Turkish gum tragacanth sam?ples from Astragalus kurdicus and Astragalus gummifer (minor sources) The Test Article used in a dietary study of gum tragacanth in Man was shown to have been well-chosen, representing gum tragacanth of fair average quality.
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Pickles, Neil Anthony. "Characterisation and differentiation of Acacia species, gum ghatti and gum tragacanth exudates using chemical and immunological techniques." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486937.
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Bergecliff, Terese. "Viscosity and Acid Stability in Low-fat Mayonnaise with Varying Proportions of Xanthan Gum and Guar Gum." Thesis, Linnéuniversitetet, Institutionen för kemi och biomedicin (KOB), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-57484.
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Mayonnaise is a mixture of egg yolk, vinegar, water, spices and 70-80% oil forming a semi-solid oil-in-water emulsion. When preparing a low-fat mayonnaise with an increased water content, thickening agents are required for increased viscosity and emulsion stability. The hydrocolloids xanthan gum and guar gum are sometimes used for this purpose and they act synergistically creating a viscosity increase. However, guar gum has poor acid stability, and because mayonnaise is an acidic product guar gum will eventually start to degrade causing a viscosity decrease and subsequent emulsion separation. Despite this fact, guar gum and xanthan gum are extensively used in mayonnaises today. The aim of this degree project was to explore how the synergy between guar gum and xanthan gum influences the viscosity of a low fat mayonnaise and whether high acidity will have an impact on the viscosity over a 4-week period. This was to examine if and if so, how a mayonnaise recipe can be modified to maintain a cost efficient product with the desired rheological properties in times of hydrocolloid price fluctuations. The study was conducted by preparing 15 mayonnaises with 50% fat, either at pH 3,5; 4 or 5 and a total of 0,6 % hydrocolloids with varying proportions of guar gum and xanthan gum. The mayonnaise samples were studied by measurements of viscosity, color changes and a visual comparison of their mayonnaise-like flow-properties compared to Hellmann’s Real Mayonnaise used as reference. The viscosity of the mayonnaises increased with increasing ratio of guar gum. On the other side, there were greater viscosity losses in mayonnaises with increasing ratio of guar gum 4 weeks after preparation compared to 4 days, with no apparent signs of correlation between higher acidity and hydrocolloid degradation. Mayonnaises with 20% xanthan gum and 80% guar gum had the texture most similar to the reference. In these low-fat mayonnaises, the use of more xanthan gum led to an undesired “slimy” texture and a lower viscosity – an important aspect if adjusting a low-fat mayonnaise recipe by increasing the ratio of xanthan gum. Because a commercial mayonnaise sometimes is consumed several months after manufacturing, that time frame is most likely required in order to fully measure how much the high acidity in mayonnaise will affect its viscosity. This project has shown a pattern where viscosity in the assessed mayonnaises starts to decrease a few weeks after preparation. However to find out exactly to what extent and how this would affect the overall product, and ultimately: if guar gum/xanthan gum combinations are suitable for long-term mayonnaise applications, further studies are required.Viskositet och syrastabilitet i majonnäs med låg fetthalt och olika proportioner av xantan och guarkärnmjöl Majonnäs är en blandning av äggula, vinäger, vatten, kryddor och 70-80% olja som bildar en semi-solid olja-i-vatten-emulsion. För att tillverka en lågfettsmajonnäs med högre vatteninnehåll behöver förtjockningsmedel tillsättas för viskositet och emulsionsstabilitet. Hydrokolloiderna xantangummi och guarkärnmjöl används ibland i detta syfte och de utövar en synergi som ger ökad viskositet. Dock har guarkärnmjöl dålig syrastabilitet och eftersom majonnäs är en sur produkt kommer guarkärnmjölet efter ett tag att brytas ned vilket leder till en viskositetsminskning och emulsionsseparation. Trots detta används guarkärnmjöl och xantangummi i stor utsträckning i majonnäser idag. Syftet med examensarbetet var att undersöka hur synergin mellan guarkärnmjöl och xantangummi påverkar viskositeten i en lågfettsmajonnäs och huruvida en hög syrahalt kommer att påverka viskositeten under en 4-veckorsperiod. Detta för att se om och i så fall hur ett majonnäsrecept kan modifieras för att erhålla en kostnadseffektiv produkt om priset på hydrokolloider växlar. För arbetet bereddes 15 majonnäser med 50% fetthalt, antingen med pH 3,5; 4 eller 5 och totalt 0,6% hydrokolloider med olika proportioner av guarkärnmjöl och xantangummi. Majonnäserna undersöktes genom mätning av viskositet, färgförändringar och en visuell jämförelse av deras majonnäsliknande flytegenskaper i förhållande till Hellmann’s Real Mayonnaise som användes som referens. Viskositeten i majonnäserna ökade med ökande halt guarkärnmjöl. Å andra sidan minskade viskositeten i högre grad med ökande halt guarkärnmjöl 4 veckor efter tillverkning jämfört med 4 dagar, men inga tydliga samband mellan högre syrahalt och nedbrytning av hydrokolloider syntes. Majonnäser med en blandning av 20% xantangummi och 80% guarkärnmjöl hade den konsistens som var mest lik referensen. I dessa försök med lågfettsmajonnäser ledde användandet av högre halt xantangummi till en oönskad ”slimig” textur och en lägre viskositet – en viktig aspekt om ett recept på lågfettsmajonnäs ska modifieras genom att öka halten xantangummi. Eftersom en kommersiell majonnäs ibland konsumeras flera månader efter tillverkning så är det troligtvis den tidsramen som krävs för att helt kunna mäta hur mycket den höga syrahalten i majonnäs kommer att påverka dess viskositet. Detta projekt har påvisat ett mönster där viskositeten i de analyserade majonnäserna börjar minska några veckor efter tillverkningen. Men för att få reda på exakt i vilken utsträckning och hur detta skulle påverka produkten i sin helhet, och i slutändan: om kombinationen med guarkärnmjöl och xantangummi är lämplig för majonnäser med lång hållbarhet krävs ytterligare studier.
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Elhadi, Hanan. "Evaluation of gum arabic reforestation as a measure for combating desertification in the gum belt area of Sudan." Weikersheim Margraf, 2008. http://d-nb.info/993761275/04.
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Otto, Stephanus Daniel. "Chewing gum therapy in third molar surgery." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_4769_1222844033.
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The aim of this study was to determine how effective a chewing gum regime is in treating the common minor complaints of third molar surgery. The efficacy of a six-day chewing gum regimen in reducing pain, swelling and trismus after third molar surgery was compared to no chewing gum therapy. Third molar surgery is an important part of any maxillofacial surgery practice. There is an ongoing quest to find new and innovative methods to treat the minor complaints of this procedure.
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Cassanelli, Mattia. "Drying and rehydration of gellan gum gels." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8810/.
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This research shows, for the first time, the freeze dried low acyl (LA) gellan gum, high acyl (HA) and HA:LA mixture gel structures and their properties upon rehydration. The water interaction with the gel structure is affected by the presence of acyl groups along the HA gellan gum polymer chain. The rehydration rate was shown to be lower for HA gellan gum and was not dependent on the polymer concentration. In the second instance, the effect of the gel pH on the freeze- and oven-dried structure is studied as well as the water re-absorption extent and rate. In this part, two drying methods, freeze- and oven-drying, were performed. Finally, a comparison of the three drying processes (freeze-, oven- and supercritical-fluid drying) is reported, proposing the effect on the molecular structure by investigation of the disordered chain domains of the gel network. As supercritical-fluid drying requires a pre-treatment in alcohol, its effect on the gellan gum network was investigated. It is shown how alcohols change the gellan gum configuration, leading to a considerable variation in gel texture. A novel supercritical-fluid batch rig is also proposed, characterised by high process flexibility and reduced set-up and energetic costs, particularly suitable for small/laboratory-scale use.
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Ashayeri, Diane L. "Soy protein-xanthan gum interaction:stability and rheology." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/91074.
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This study investigated the effects of ionic strength, pH, gum concentration, and protein type on protein - xanthan gum interactions. Commercial soy sauce and tamari sauce as well as model systems of soy protein isolate and whey protein concentrate were the sources of protein used for evaluation with xanthan gum.
Preliminary research indicated that when either soy sauce or tamari sauce were mixed with xanthan gum, stable solutions with notable viscosity synergisms resulted. The soy protein and whey protein systems were subsequently prepared with a range of 0 to 5% added sodium chloride. Results indicated that an equilibrium existed between proteins and xanthan gum such that increased sodium chloride initially increased solution stability; but when in excess, the sodium chloride led to a loss of protein - xanthan gum solution solubility and in some cases to precipitation. Precipitation was also noted at the pH extremes of 2,3, and 9 and when xanthan gum was present in excess, or at 0.25%.
The effects of sodium chloride, protein type, and pH on the rheological parameters of model solutions were also examined. Higher sodium chloride levels yielded greater viscosity synergisms. Those solutions made.with intact protein were generally higher in apparent viscosity than similar solutions made with hydrolyzed protein. Solutions at pH 5 were generally higher in viscosity than were similar solutions at pH 7.
Several factors that appeared to affect the stability, solubility, and the rheological parameters of protein - xanthan gum solutions were sodium chloride concentration, gum concentration, pH, and protein type.M.S.
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Burch, Coleman Patrick. "Adhesion Fundamentals in Spotted Gum (Corymbia citriodora)." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/78206.
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The goal of this project was to advance adhesion science and technology related to the Australian hardwood spotted gum (Corymbia citriodora). Plantation-grown spotted gum exhibits poor adhesion properties in comparison with similar woods, such as Gympie messmate (Eucalyptus cloeziana). To better understand adhesion differences between these two woods, this research compared and contrasted the surface chemistries of plantation-grown spotted gum and Gympie messmate with a particular focus on sensitivity to thermal deactivation.
Wetting measurements were performed using the sessile drop method. Initial and equilibrium contact angles, time-dependent wetting, and surface energy were determined. Time-dependent wetting and equilibrium contact angles were most informative. Initial contact angles and surface energy calculated with them were misleading and often generated anomalous results.
Heating water-saturated wood to mild surface temperatures (105 deg C, directly after evaporative cooling) severely deactivated spotted gum but not Gympie messmate. This suggests conventional kiln drying appears unsuitable for spotted gum while amenable for Gympie messmate. Spotted gum likely requires non-aqueous, low surface tension adhesives or aqueous adhesives formulated with surface active wetting agents.
Water-saturation (followed by room-temperature vacuum drying) substantially altered the surface chemistries of both woods, making them more hydrophilic. Consequently, the question was raised of whether a water-spray onto the wood surface prior to adhesive application could improve bonding. If so, this simple, industrially-feasible treatment could prove very beneficial to the wood composites industry. Water-saturation also revealed differences in the two wood's water permeability, which has implications for adhesive penetration and wood drying and may additionally help explain adhesion differences.
Analysis of the plantation-grown heartwood (inner, middle, and outer heartwood regions) revealed significant wetting differences on spotted gum with only minor differences on Gympie messmate.
The Australian woods were compared to two North American woods-loblolly pine (Pinus taeda) and Douglas-fir (Pseudotsuga menziesii). Examining water wetting measurements, the Australian and North American woods exhibited some interesting similarities. However, methylene iodide wetting measurements revealed that the Australian woods were quite different from the North American samples studied here.Master of Science
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Nep, E. I. "Grewia polysaccharide gum as a pharmaceutical excipient." Thesis, Aston University, 2010. http://publications.aston.ac.uk/10310/.
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Grewia gum is obtained from the inner stem bark of the edible plant Grewia mollis Juss (Fam. Tiliaceae) which grows widely in the middle belt region of Nigeria, and is also cultivated. The dried and pulverised inner stem bark is used as a thickening agent in some food delicacies in that region of the country. This ability of the material to increase solution viscosity has generated a lot of interest and is the catalysing momentum for this research. Such materials have been used as stabilizers or suspending agents in cosmetics, foods and liquid medications, and as mucoadhesives and controlled release polymeric matrices in solid dosage forms. The physicochemical characterization of candidate excipients forms an essential step towards establishing suitability for pharmaceutical application. For natural gums, this usually requires isolation of the gum from the storage site by extraction processes. Grewia polysaccharide gum was extracted and dried using techniques such as air-drying, freeze-drying or spray-drying. Component analysis of the gum showed that it contains five neutral sugars: glucose, galactose, rhamnose, arabinose and xylose. The gum contains traces of elements such as zinc, magnesium, calcium and phosphorus. At low substance weight, the gum hydrates in aqueous medium swelling and dispersing to give a highly viscous dispersion with pseudoplasmic flow behaviour. The method by which drying is achieved can have significant effect on some physicochemical properties of the gum. Consequently, the intrinsic viscosity and molecular weight, and parameters of powder flow were shown to differ with the method of drying. The gum has good thermal stability. In comparison with established excipients, grewia gum may be preferable to gum Arabic or sodium carboxymethylcellulose as a suspending agent in ibuprofen suspension formulations. The release retardant property of the gum was superior to guar and Metolose® in ibuprofen matrices. Similarly, carboxy methylcellulose, Methocel®, gum Arabic or Metolose® may not be preferable to grewia gum when controlled release of a soluble drug like cimetidine is indicated. The mucoadhesive performance of the gum compared favourably with excellent mucoadhesives such as hydroxypropyl methylcellulose, carboxymethylcellulose, guar and carbopol 971 P.
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Woermann, Beate. "Radio observation of the Gum Nebula Region." Thesis, Rhodes University, 1997. http://hdl.handle.net/10962/d1005271.
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This thesis describes the results of an investigation of the physical properties of the Gum Nebula. For this investigation a radio continuum map of the region was made at 2326 MHz and resolution ⅓° with the HartRAO antenna. This map was used to generate spectral index images and an infrared to radio flux density ratio (IRR) image. The latter image shows that the IRR of the nebula is in the range 20 to 250, identifying it as an old SNR. Several spectral index images of this region were generated using two different methods, one based on the isolation of the nebula from its background radiation, the other based on TT-plots (Turtle et al., 1962). The two methods yield similar results, which show that the nebula has a thermal shell with a non-thermal region in its interior. Below the galactic plane the thermal region dominates and above the plane the nonthermal region. These results suggest a model of an old SNR with an H II region shell. Spectral line observations of hydrogen recombination lines and hydroxyl (OH) were made with the HartRAO and the Mopra telescopes. The detection of hydrogen recombination lines at four positions in the thermal regions of the nebula give electron temperatures and emission measures in the ranges 4000 to 6000 K and 220 to 460 pc.cm⁻⁶ respectively. The turbulent velocities are of the order of 20 km/s. A search for shocked OH lines at 1667 MHz and 1720 MHz in the Gum Nebula gave results that were negative, but numerous unshocked 1667 MHz OH lines were detected. The latter were used in a test for an expansion of the nebula. The most plausible fit to the data gives an expansion centre at l = 260.5°, b = -2.5° and at a distance of 0.7 kpc from us. The front face angular radius and expansion velocity are 10.5° and 16 km/s respectively. The back face angular radius and expansion velocity are 8.50 and 7 km/s respectively.
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Muniz, João Renato Carvalho. ""Aplicação da bioinformática no estudo dos genes e enzimas envolvidos na síntese da goma fastidiana produzida pela xylella fastidiosa"." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-09052005-165542/.
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Xylella fastidiosa é uma bactéria Gram-negativa, limitada ao xilema das plantas e o agente causador de diversas doenças em importantes plantações como citros, videiras, mirta, amêndoa, arbustos e café. Em citros, X. fastidiosa causa a Clorose Variegada dos Citros (CVC) ou amarelinho. Nove enzimas (GumB, C, D, E, F, H, J, K e M) estão envolvidas nas etapas biossintéticas de um polissacarídeo extracelular (EPS), chamado de goma fastidiana, um dos mecanismos envolvidos na patogênese da bactéria. Essas enzimas catalisam reações de adição de açúcares, polimerização e exportação do EPS através da membrana da bactéria. No presente trabalho, ferramentas de bioinformática foram utilizadas para o estudo e entendimento da biossíntese da goma fastidiana. As nove enzimas foram estudadas quanto ao seu conteúdo de estrutura secundária, análise de hidrofobicidade e das regiões transmembrânicas, classificação quanto as suas funções. A construção de modelos estruturais para as enzimas Gums através de comparação por homologia seqüencial mostrou ser um processo impossível, devido a falta de moléculas homólogas com estruturas tridimensionais conhecidas. Por outro lado, métodos de reconhecimento de enovelamento mostraram bons resultados e comparações entre as estruturas secundárias das enzimas Gums foram calculadas com a utilização dos programas GenThreader e THREADER 3.3. Modelos tridimensionais para as enzimas GumB, GumK, GumM, GumJ e GumC foram construídos com o programa MODELLER 6.0a e validados com o programa Procheck e VERIFY 3D. Para construção do modelo da GumH (enzima que catalisa a adição da GDP-manose em um lipídio carreador poliprenol), o GenThreader encontrou similaridades quando comparada a MurG (E.coli), 2-epimerase (E. coli), GtfB (Amycolatopsis orientalis) e beta-GT de fago T4. Todos os modelos são bastante semelhantes e compostos por dois domínios (alfa/beta), ambos similares ao motivo de ligação de nucleotídeos Rossmann fold e separados por uma fenda profunda, que, provavelmente, forma o sítio de ligação da GDP-manose. Estudos da interação entre proteína e substrato foram obtidos com a utilização do programa FLO. O alinhamento seqüencial da GumH com outras onze glicosiltransferases mostrou regiões bastante conservadas, incluindo o motivo EX7E presente no sítio de ligação do substrato na proteína. Considerações a respeito das interações do substrato GDP-manose com a enzima GumH e do mecanismo da reação foram feitas. Essas análises enfatizam o modelo obtido para a GumH, que representa a primeira estrutura proposta para as enzimas envolvidas na síntese da goma fastidiana.Xylella fastidiosa is a xylem-dwelling, insect-transmitted gamma-protobacterium that causes pathogenicity in citrus plants and many others important crops such as grapevine, periwinkle, almond, oleander and coffee. In citrus plants, X. fastidiosa causes citrus variegated chlorosis (CVC) or amarelinho. Nine enzymes (GumB, C, D, E, F, H, J, K and M) are involved in the biosynthetic pathway of an exopolysaccharide (EPS) called fastidian gum which could be involved in the pathogenicity of the bacterium. These enzymes catalyses sugars addition reactions, polymerization and discharge of the EPS through the bacterias membrane. We have used bioinformatic tools to study these enzymes and to understand the gum biosynthesis. The nine enzymes were studied regarding to its secondary structure content, analysis of hidrophobicity and transmembrane regions, and yet function classification. The construction of structural models using sequential homology was shown to be impossible, due to the necessity of homologues molecules whose three-dimensional structures are known. On the other hand, pairwises comparisons of secondary structures showed good results and were realized with GenThreader and THREADER 3.3 programs. Three-dimensional structures to GumB, GumK, GumM, GumJ and GumC enzymes were constructed using MODELLER 6.0a and validated with Procheck and VERIFY 3D programs. To construct the model of GumH (enzyme that catalyse the addiction of a GDP-mannose on a polyprenol phosphate carrier), GenThreader found folding similarities when compared to MurG and UDP-Acetylglucosamine 2-Epimerase (from E. coli), GtfB (from Amycolatopsis orientalis) and beta-GT (from T4 phage). The models are very similar consisting of two alpha/beta open sheet domains, both alike in topology to the Rossmann nucleotide-binding folds, and separated by a deep cleft which probably forms the GDP-mannose binding site. Studies of the interaction between enzyme and docked substrate were carried out using the FLO program. The sequence alignment between GumH and another eleven glycosiltransferases showed several preserved regions including the EX7E motif present on the substrate binding site. The interactions between enzyme-GDP-mannose substrate and the mechanism of the reaction were studied. These analyses emphasize the three-dimensional model constructed for GumH that represents the first structural information for enzymes involved in fastidian gum synthesis.
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Gibson, Voss. "The development of an easily removable chewing gum." Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658204.
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Mounting concerns require a solution to a worsening problem of chewing gum litter. Existing methods of removal are costly and ineffective. One solution requires the modification of chewing gum by the incorporation of amphiphilic graft copolymers. The synthesis of amphiphilic graft copolymers, their incorporation into chewing gum compositions, analysis of such compositions and results from trials testing ch€wing gum removability are described. Modified samples, incorporating an amphiphilic graft copolymer (REV -7) were found to be much easier to remove than -control samples.
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Israelsson, Axel. "Chewing gum and human hair as retrospective dosimeters." Doctoral thesis, Linköpings universitet, Avdelningen för radiologiska vetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-108892.
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Retrospective dosimeters are sometimes needed after radiological/nuclear (RN) exposures to determine the doses to individuals. Conventional dosimeters may not be at hand or may not be applicable calling for alternative materials. The possible exposure situations can be divided into external and internal; the radiation field stems either from outside the body or from a source within. This thesis investigates the possibility to use chewing gum and hair as retrospective dosimeters. The chewing gum would be used after an unexpected radiation event of external type whereas human hair is examined after chronic intake of uranium. Chewing gum containing xylitol and sorbitol was analyzed using electron paramagnetic resonance (EPR) and the hair was analyzed by alphaspectrometry following radiochemistry and by synchrotron radiation microbeam x-ray fluorescence (SR μ-XRF). Xylitol and chewing gum (in this particular case, V6) are in the present work found to be valuable dosimeters after unexpected radiation events. The xylitol signal linearity with dose in the interval 0-10 Gy was confirmed (r2=1.00). The doses to the coating of the chewing gums were determined 4-6 days after irradiation with an uncertainty of less than 0.2 Gy (1 SD). Spectral dependence with time after exposure was found, but was, however, minimal between 4-8 days. Hair was evaluated and compared with urine as biodosimeter after ingestion and inhalation intake of uranium. Concentrations of 234U and 238U and their activity ratios were measured in the hair, urine and drinking water sampled from 24 drilled bedrock well water users in Östergötland, Sweden, as well as among 8 workers at a nuclear fuel fabrication factory, Westinghouse Electric Sweden. The results show that there is a stronger correlation between the uranium concentrations in the drinking water of the well water and the users’ hair (r2 = 0.50) than with their urine (r2 = 0.21). There is also a stronger correlation between the 234U/238U activity ratios of water and hair (r2 = 0.91) than between water and urine (r2 = 0.56). The individual absorbed fraction of uranium, the ƒ value, calculated as the ratio between the excreted amount of uranium in urine and hair per day and the daily drinking water intake of uranium stretched from 0.002 to 0.10 with a median of 0.023. The uranium concentrations of the fuel factory workers’ hair and urine were also obtained as well as that of personal air sampler (PAS) filters for the determination of inhaled uranium activity. A large day-to-day variation (7-70 Bq d-1) of the inhaled 234U activity was seen over a 6 week period. Over a 12 week period the 234U activity concentration in urine was similarly seen to vary from 2 to 50 mBq kg-1. Four hair samples from the same subject and period showed less variation (100-240 mBq g-1). The uranium inhalation to urine and hair factors finh,u and finh,h were found to be 0.0014 and 0.0002 respectively given by calculations based on the measured PAS, urine and hair data from two individuals. The SR μ-XRF measurements showed that uranium is present in an outer layer of the hair shaft, about 10-15 μm wide. The measurements also revealed particles containing uranium being present on the surface of unwashed hair shafts. However, the washed hair shafts showed few, if any, particles. This thesis concludes that chewing gum and hair can be used as retrospective dosimeters after external radiation and after intake of uranium respectively.
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Osman, Mohamed Elmubarak. "Fractionation and characterisation of gum from Acacia senegal." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336168.
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Manning, Harriet. "The fractionation of gum arabic using synthetic membranes." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687326.
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Gum arabic is a natural product used widely in the food industry as an emulsifier and stabilising agent. The gum contains 3 main fractions: an arabinogalactan (~80 wt%; AG) fraction, a glycoprotein (~ 2 wt%; GP) fraction and an arabinogalactan-protein complex (~18 wt%; AGP). This AGP fraction is largely responsible for the functional properties of gum arabic and, due to natural variation, the proportion of AGP within a gum arabic batch varies enormously. There is industrial interest, therefore, in fractionating the gum arabic to allow creation of a more homogenous product, as well as new products for the food industry. The aim of this work was to investigate the feasibility of using membrane technology to fractionate gum arabic. Polymeric membranes were used initially and showed success at rejection of AGP by size exclusion. Polysulfone membranes of 0.1, 0.5 and 0.8 μm nominal pore size were employed and the rejection of AGP was seen to decrease with increasing pore size, but the overall transmission of solids was seen to increase. Beneficial fouling was observed with the larger two pore sizes, which allowed greater fractionation after a fouling layer had developed. It was hypothesised that the 0.1 μm PS membrane was fouled by mainly cake formation, whereas the 0.5 and 0.8 μm PS membranes were subject to more in pore fouling. The critical flux of gum arabic was measured for these three pore sized membranes and was found to be highest (27 L m-2 h-1) for the 0.1 μm PS membrane. This was attributed to the lack of in pore fouling, which the 0.5 and 0.8 μm membranes suffered and resulted in fouling occurring at lower fluxes for these membranes; the critical fluxes for these membranes was found to be 15 and 22 L m-2 h-1, respectively Increasing the crossflow velocity (CFV) from 0.18 to 0.67 m s-1 was found to increase the critical flux. Filtration experiments above and below the critical flux for each pore size demonstrated the efficiency of operating below the critical flux, as operation could be sustained for much longer periods (up to 4h was tested) without the need for cleaning cycles. It also demonstrated the beneficial effect of the fouling layer with the 0.5 iii and 0.8 μm membranes, which showed little or no fractionation during operation below the critical flux. Finally, filtration studies were carried out with 3 different membrane materials and detailed surface analysis was performed to explain the differences in performance observed. Both polysulfone and fluoropolymer membranes were fairly hydrophobic, with contact angles of between 70 and 90º, and showed very high overall rejection of solids. High transmission of solids is required together with good rejection of AGP for an effective fractionation process. Hydrophilic cellulose acetate, however, showed very high transmission of gum arabic (~ 75%), but no rejection of AGP. Overall, the work has shown that fractionation of gum arabic with membranes is feasible using polysulfone membranes, but that further work is needed to optimise the separation. Higher transmission of the GP and AG are required whilst maintaining rejection of the AGP.
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Wang, Weiping. "Analytical and structural studies of plant gum exudates." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/11943.
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Studies presented in this Thesis fall into four distinct groups: 1. Analytical characterizations have been made of the gum exudates from: (a) Eight species of the Series Gummiferae and Vulgares and three highly proteinaceous species of the Series Juliflorae of the genus Acacia; (b) Six species from the genus Leucaena which are chemically very close to gum arabic; (c) Nine specimens of gum obtained from Combretum nigricans growing in different locations; (d) Six A.senegal gum samples from Uganda and a further six 'gum arabic' samples from different regions; (e) Seventeen species of gum exudates from 15 different genera such as Cassia grandis, Cercidium praecox, Parkia nitida, Prosopis chilensis, Sesbania sesban, Atalaya hemiglauca, Sclerocarya birrea, Pseudocedrela kotschyi, Senna nicaraguensis, etc. 2. A study of some of the structural features of Combretum nigricans gum by Smith-degradation showed that uronic acid and rhamnose groups occur in internal locations within the overall structure, and not as end-groups as is the case in gum arabic (A.senegal). 3. Amino acid data and 13C NMR spectra are presented for various fractions of A.senegal gum and for some highly proteinaceous Acacia gums (e.g. A.difficilis, A.eriopoda, A.tumida). The effect of enzymes on these gums is reported. 4. 13C NMR spectra for thirty different gum exudates are presented to show the characteristic 'fingerprint' patterns given by their polysaccharide structures. Information concerning their component monosaccharides, anomeric configurations, and linkages between the various sugar residues is given by spectrum analysis. This provides a most sensitive way to identify botanical species based on the total structure of exuded gums. The arabinose form (pyranose or furanose) and the various linkage configurations (α or β) in the gum structures are important and directly affect the physico-chemical behaviour of gum exudates. Acacia gums in which rhamnose is absent (or nearly absent) generally have a large proportion of β-L-arabinopyranose (A.seyal, A.sieberana, A.arabica gums etc.).
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Dhameri, Sulaiman Ali A. "Rheological Properties and Decomposition Rates of Gellan Gum." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1562780919692096.
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Morjaria, Yamini. "The release of nicotine from chewing gum formulations." Thesis, Aston University, 2004. http://publications.aston.ac.uk/11062/.
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A series of nicotine gums was made to investigate the effect of formulation variables on release of nicotine from the gum. Using a directly compressible gum base, in comparison to Nicorette® the gums crumbled when chewed in vitro, resulting in a faster release of nicotine. To investigate the effect of altering the gum base, the concentration of sodium salts, sugar syrup, the form of the active drug, the addition sequence and the incorporation of surfactant into the gum, the traditional manufacturing method was used to make a series of gum formulations. Results showed that the time of addition of the active drug, the incorporation of surfactants and using different gum base all increased the release of nicotine from the gum. In contrast, reducing the concentration of sodium carbonate resulted in a lower release. Using a stronger nicotine ion-exchange resin delayed the release of nicotine from the gum, whilst altering the concentration of sugar syrup had little effect on the release but altered the texture of the gum.
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Randall, Richard Christopher. "Molecular characterisation and functional properties of gum arabic." Thesis, University of Salford, 1992. http://usir.salford.ac.uk/43001/.
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Semi-PreParative gel permeation chromatography (gpc) was used to isolate several molecular mass components of gum arabic. The u. v. (218 nm) gpc elution profile showed the presence of several prominent peaks; however, only one major peak (FAw 3.8 x 10-9 g moll) and a minor peak (FAw 1.45 x 106 g mol-1) were observed in the differential refractive index (R. I. ) gpc elution profile. The Rl. molecular mass distribution profile was also shown to be representative of the true mass distribution of the gum. Gram quantities of three apparently "pure" components of gum arabic were prepared using hydrophobic interaction chromatography. These components corresponded to the three major peaks observed in the u. v. gpc elution profile. Extensive physico-chemical analysis revealed that gum arabic consists of:- a: a major protein deficient arabinogalactan representing 900/6o f the total gum mass: b: a high molecular mass, protein rich (100A protein) component, designated as an arabinogalactan-protein complex which accounts for 9% of the total gum: c: one or more protein enriched (50% protein) glycoprotein components accounting for only 1% of the total gum. Furthermore. the result of enzyme treatment indicates a possible structural correlation between the arabinogalactan and the arabinogalactan-protein complex. This evidence also substantiates the so called 'Wattle Blossom" model which Is representative of the macrostructure of the high molecular mass arabinogalactan-protein complex. The Newtonian rheological behaviour of aqueous gum Arabic solutions (up to 400/6 w/w) complements other experimental evidence, which strongly suggests that the gum's macromolecular structure is very compact for a polysaccharide. The unique emulsification properties of the gum were monitored by the development of standardised turbidimetric techniques. It was subsequently shown that enzyme and heat treatment of the gum had a similar effect of substantially reducing the emulsifying efficiency of the gum. Both gum treatments effectively "denature" the proteinaceous components of the gum and by consideration of other experimental evidence (adsorption characteristics of the components at the o/w interface) it was demonstrated that the high molecular mass arabinogalactan-protein complex is solely responsible for the gum' s emulsifying property.
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Al-Shehry, Jaber Mohammed. "EFFECT OF GUAR GUM ON VEGETABLE TRANSPLANT GROWTH." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275440.
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Souther, Brandy Jolene. "The Effect of Xanthan Gum and Guar Gum on Enhancing the Quality and Preventing Lipid Rancidity in Yeast Bread Supplemented with Flaxseed." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/43920.
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This study examined the effects of guar gum and xanthan gum on flax supplemented breads through objective and sensory testing. Breads containing flaxseed and gums were found to have a significantly (p<0.05) higher water activity than the control bread. Control bread was also found to have a higher (p<0.05) volume while flax breads containing guar gum had a significant (p<0.05) decrease in volume. Control bread and bread containing guar gum were significantly (p<0.05) harder in crumb texture. Breads with flax and xanthan gum displayed a significant (p<0.05) amount of springiness. While there was no significant (p>0.05) difference in peroxide values among bread samples, control bread had a lower (p<0.05) anisidine value indicating a decrease in hydroperoxide breakdown. While not significant (p>0.05), bread containing xanthan gum had a lower anisidine value than the other treatments. Sensory analysis found bread with both gums to be moister (p<0.05) and have a strong (p<0.05) yeasty aroma and fresher flavor. Control bread was found to have the least (p<0.05) yeasty aroma and taste significantly (p<0.05) less bitter but more stale.Master of Science
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Poštulková, Hana. "Chemické modifikace hydrogelů z přírodního polysacharidu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-217058.
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V teoretické části práce by shrnuty chemické a fyzikální vlastnosti, chemická struktura a využití přírodního polysacharidu gum karaya. Hlavním cíle diplomové práce byla alkalická modifikace původní nerozpustné gum karayi na rozpustný produkt, který může být v budoucnu využit pro další aplikace například v medicíně. Nerozpustnost gum karayi je způsobena přítomností acetylových skupin a vícemocných iontů ve struktuře polysacharidu. Byly zkoumány optimální podmínky pro modifikační proces. Pro modifikaci byl použit hydroxid sodný, draselný nebo amonný a čas modifikace od 1 minuty po 24 hodin pro roztok originální gum karayi s koncentrací od 0,1 do 3 %. Pro určení chemického složení originálního a modifikovaných vzorků byla využita FTIR. Bylo prokázáno, že vzorky A2, B1 - 7, C1 - 8 a E1 - 2 byly zcela deacetylovány, protože pás pro acetylovou skupinu nebyl v FTIR spektrech pozorován. Odstranění acetylových skupin alkalickou modifikací bylo taktéž potvrzeno 13C CP MAS NMR. Pomocí XRD byl prokázán amorfní charakter originálního vzorku. Množství vlhkosti a teplotní stabilita vzorků byly zkoumána pomocí TGA. Bylo zjištěno, že termální stability originální gum karayi je vyšší než u modifikovaných vzorků. Termální stabilita modifikovaných vzorků byla ovlivněna reakčními parametry. Entalpické změny vzorků byly studovány pomocí DSC, nicméně nebyly pozorovány žádné významné rozdíly mezi modifikovanými vzorky a originální gum karayou. Prvkové složení bylo určeno pomocí ICP-OES a byla potvrzena přítomnost vápníku, draslíku a hořčíku ve struktuře polysacharidu. Molekulová hmotnost modifikovaných vzorků byla měřena pomocí GPC a byla stanovena na 8 milionů g·mol-1. Reologické měření roztoků gum karayi bylo provedeno pro určení lineární viskoelastické oblasti. Dále byl sledován efekt NaCl na viskozitu originálního vzorku. Viskozita klesala s vyšším množstvím NaCl. Pokles viskozity originálního vzorku je způsoben výměnou vápenatých iontů za sodné, což vede k uvolnění fyzikálně vázané struktury a tím k vyšší rozpustnosti vzorku ve vodě.
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Argent, Robert Murray. "Dendroclimatological investigation of river red gum (Eucalyptus camaldulensis Dehnhardt)." Connect to thesis Access electronic version, 1995. http://thesis.lib.unimelb.edu.au/adt-root/public/adt-VU2001.0019/index.html.
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Typescript. Includes bibliographical references (leaves [279]-287) This thesis examines the growth ring structure of Eucalyptus camaldulensis Dehnhardt and investigates links between ring features and the climatic conditions under which growth took place. Samples of E. camaldulensis from the Barmah Forest (near the River Murray in northern Victoria) were used in the study. E. camaldulensis growth is linked to periodic flooding, and the Barmah Forest contains sites that are frequently flooded. Wood samples were obtained from sites subject to different average flooding frequencies. Trees used in the study grew out of natural regeneration in the 1920's and 1930's and from regeneration trials in the early 1960's. Initial investigation of E. camaldulensis samples revealed ring-like features that were able to be traced on samples by eye. Microscopic investigation showed that there existed considerable variations in the properties of individual rings at different positions on the samples, and that the boundaries between rings were often indistinct. Further examination of E. camaldulensis microstructure was performed on samples from two trees that grew on sites with significantly different flooding regimes. These samples possessed features that formed rings, with rings being successfully matched between samples taken from different heights in the trees. As the complex microstructure of E. camaldulensis did not lend itself to standard dendroclimatological techniques, methods were developed to facilitate the comparison and matching of rings. These methods were also used in the successful matching of ring patterns with the output from a simple climate-based tree growth model. Two sets of E. camaldulensis samples (BS1, with 33 samples, and BS2, with 39 samples) were studied to assess the level of individual variability in ring patterns, and to provide a representative ring pattern for climate comparison. Following the development of methods for identifying samples with similar ring patterns, a subset of similar samples was selected from the BS1 set. A member of this subset was selected to provide a ring-width pattern upon which a representative pattern of ring features for BS1 was based. The rings of the BS2 samples possessed poorer ring definition than the BS1 samples and provided no new or different information. Consequently, the representative ring pattern for BS1 was used in a dendroclimatological investigation for the site. The ring pattern was matched with the output from two tree growth event models. Although rings were matched with growth events over a 27 year period, the high variability of individual ring features prevented matching of particular types of ring features with particular types of climatic events. An investigation of numerical methods for matching ring patterns with ring or growth event patterns, and for identifying samples with similar ring patterns, was performed using signal smoothing and filtering techniques and a dynamic time-warping procedure. Ring matching and identification of similar ring patterns was found to be most successful on samples where the ring patterns, expressed as continuous signals, had similar mean and amplitude values. The techniques were unsuccessful in the matching of signals of different form, such as continuous ring pattern signals and discontinuous growth event signals.
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Young, Niall William George. "The solution properties of hydrophobically modified guar gum derivatives." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360604.
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Barbosa, Manuella MacÃdo. "Purification process of cashew gum: technical and environmental aspcts." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15184.
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CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel SuperiorThe cashew gum is a heteropolysaccharide, exudate of cashew tree, which presents with an innovative alternative to the better utilization of cashew crop. This study is pioneering and innovative because it uses the combined ethanol precipitation and application of ultrasound to increase yields and improve technological characteristics of cashew gum.The exudate cashew has attracted attention due to its characteristics of sustainability, biodegradability and biosafety. The objective of this work was to study the influence of grain size, temperature, time, alcohol ration and application of ultrasound parameters in the purification of cashew gum. The reduction in color of the cashew gum by adsorption on amberlite resins, thermogravimetric characteristics of this polysaccharide and the environmental impact caused by the purification of cashew gum in laboratory scale were evaluated also. For purification of cashew gum, nodules were first crushed and dried at 60 Â C. For the selection of purification parameters exudates smaller size of particles than 2 mm, 1 mm , 500 and 250 microns in increments temperature 20-70 Â C and time 15 to 120 minutes were studied . After selecting the parameters, the particles were milled, sieved, solubilized, filtered, decanted and dried, producing a purified gum. It was observed that the temperature does not significantly influence the solubility of the cashew gum. It has been found that the use of ultrasound in the purification process of the cashew gum accelerates the nucleation, resulting in better yields, in shorter rest time for the precipitation. The best conditions for the purification of gum were as follows: size of particle of 500 microns, time of agitation of 30 minutes, temperature at 30 Â C, the proportion of the solution cashew gum/ ethanol (v / v) of 1:4.5, application of ultrasound for 2 minutes and precipitation time of 90 minutes. Amberlite resins which showed better performance in discoloration of cashew gum were the FPA- 54, SP - 850 and XAD - 4. It was observed that the glass transition temperature of cashew gum was similar to that of arabic gum, being around 50 Â C, and the temperature of onset of thermal decomposition of this polysaccharide ( 241.5 Â C) is higher than the arabic gum ( 210.3 Â C ) , thus the cashew gum is being promising as the encapsulating agent for food and pharmaceutical industry. It was found that the steps that generated the highest percentage of environmental impacts for obtaining the gum in laboratory scale were grinding/sieving and sedimentation.
A goma de caju à um heteropolissacarÃdeo, exsudado da Ãrvore do cajueiro, que se apresenta com uma alternativa inovadora para o melhor aproveitamento da cultura do caju. Este estudo à pioneiro e inovador, pois utiliza a precipitaÃÃo em etanol combinada à aplicaÃÃo de ultrassom para aumentar o rendimento e melhorar caracterÃsticas tecnolÃgicas da goma de cajueiro. O exsudado de cajueiro tem atraÃdo atenÃÃo devido Ãs suas caracterÃsticas de sustentabilidade, biodegradabilidade e bioseguranÃa. O objetivo deste trabalho foi estudar a influÃncia dos parÃmetros granulometria, temperatura, tempo, proporÃÃo de Ãlcool e aplicaÃÃo de ultrassom na purificaÃÃo da goma de cajueiro. TambÃm avaliou-se a reduÃÃo da coloraÃÃo da goma de cajueiro, atravÃs da adsorÃÃo em resinas de amberlite, caracterÃsticas termogravimÃtricas deste polissacarÃdeo e o impacto ambiental ocasionado pela purificaÃÃo da goma de cajueiro em escala laboratorial. Para a purificaÃÃo da goma, os nÃdulos foram inicialmente triturados e secos em estufa a 60 ÂC. Para a seleÃÃo dos parÃmetros de purificaÃÃo foram estudadas partÃculas de exsudados com granulometria menor que 2 mm, 1 mm, 500 Âm e 250 Âm em intervalos de temperatura de 20-70 ÂC e de tempo de 15 a 120 minutos. ApÃs a seleÃÃo dos parÃmetros, as partÃculas passaram por um processo de moagem, peneiramento, solubilizaÃÃo, filtraÃÃo, decantaÃÃo e secagem, dando origem à goma purificada. Observou-se que a temperatura nÃo exerceu influÃncia significativa na solubilidade da goma de cajueiro. Verificou-se que a utilizaÃÃo do ultrassom no processo de purificaÃÃo da goma de cajueiro acelera a nucleaÃÃo, resultando em melhores rendimentos, em menor tempo de descanso para a precipitaÃÃo. As melhores condiÃÃes para a purificaÃÃo da goma foram as seguintes: tamanho da partÃcula de 500 Âm, tempo de agitaÃÃo de 30 minutos, temperatura de 30 ÂC, proporÃÃo de soluÃÃo de goma/ Ãlcool (v/v) de 1:4,5, aplicaÃÃo de ultrassom por 2 minutos e tempo de precipitaÃÃo de 90 minutos. As resinas de amberlite que apresentaram melhor desempenho na descoloraÃÃo da goma de cajueiro foram a FPA-54, SP-850 e XAD-4. Observou-se que a temperatura de transiÃÃo vÃtrea da goma de cajueiro foi semelhante à da goma arÃbica, ficando em torno de 50ÂC, e que a temperatura do inÃcio da decomposiÃÃo tÃrmica desse polissacarÃdeo (241,5 ÂC) à superior à da goma arÃbica (210,3 ÂC), dessa forma, a goma de cajueiro mostra-se promissora como agente encapsulante para a indÃstria de alimentos e farmacÃutica. Verificou-se que as etapas que geraram os maiores percentuais dos impactos ambientais, durante a obtenÃÃo da goma, foram a moagem/peneiramento e a decantaÃÃo.
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Шевченко, К. Л., and І. В. Рум’янцев. "Аналіз термінів та понять невизначеності вимірювань згідно Настанови GUM." Thesis, Київський національний університет технологій та дизайну, 2020. https://er.knutd.edu.ua/handle/123456789/16557.
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GASTONE, FRANCESCA. "Guar gum improves the stability and the mobility of iron microparticles for groundwater remediation." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2549542.
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Contaminated sites managements represents in Europe one of the most serious issues.
Recent data of the European Environmental Agency (EEA) shows how soil contamination due
to industry, garbage warehousing, mining and hydrocarbons tanks leakage represents one of
the most important threats to the environment [1].
The large volume of waste and the intense use of chemicals during past decades have
resulted in numerous contaminated sites across Europe. Contaminated sites could pose
significant environmental hazards for terrestrial and aquatic ecosystems as they are
important sources of pollution which may result in eco toxicological effects [2]. Emissions of
hazardous substances from local sources could deteriorate soil and groundwater quality. Soil
contamination is mainly located close to waste land-fills, industrial/commercial activities
diffusing heavy metals, oil industry, military camps, and nuclear power plants.
The objective of relevant EU policies is to achieve a quality of the environment applying
successful technologies. To this purpose, in the last decade EU have been financed numbers
of international, multi-partner EU projects; among them, the large scale research project
AQUAREHAB (FP7 ENV 2008.3.1.1.1.) , coordinated by VITO (Belgium) and involving 19
partners, started in May 2009 and lasted 56 months, until 2013. It aimed at developing
innovative rehabilitation technologies for soils, groundwater and surface waters
contaminated by a wide range of priority contaminants (nitrates, pesticides, chlorinated
compounds, aromatic compound, mixed pollutions, ecc.). These technologies have been
developed within 5 operative work packages (WP1-5) and the guidelines and approaches
developed have been extrapolated and applied, in WP8, to real polluted sites.
The work herein presented is included in the context of WP5 and WP8 of the AQUAREHAB
EU project, in which the group of Groundwater Engineering of the Polytechnic University of
Turin is involved; its goal is to develop and apply at the real scale an effective and costeffective in-situ rehabilitation technology based on the injection of micro-sized (100 nm-100
µm) zerovalent iron (MZVI) particles directly into a contaminated aquifer in order to create a
reactive zone which is able to treat both the plumeand the source of contamination.
Injectable MZVI particles are selected because they can overcome the major hindering
factors of the widely accepted ZVI based permeable reactive barriers (PRB) (impossibility to
treat the source of contamination and considerable excavation costs), due their high
reactivity against a wide range of contaminants thanks to their high specific surface area and
to lower costs, longer lifetime and easier handling in respect with nano-sized ZVI (NZVI)
particles. Nevertheless MZVI particles disperse in water are prone to gravitational instability
and, as a consequence, the resulting mobility is limited [3, 4]. To solve this problem, the use
of a stabilizing agent able to modify suspending fluid properties is required. In the recent
year the use of biopolymer demonstrated to be successful [5, 6] although a full
comprehension of interaction mechanisms with the porous media and a complete system
characterization is still missing.
In this work, in order to meet AQUAREHAB project requirements and to overcome
technology limitations, the use of MZVI suspended in a thickening polymer solution of guar
gum hydrocolloid is considered.
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Žemaitienė, Asta. "Biologiškai vertingų komponentų įtaka valgomųjų ledų gamybos technologijai ir jų savybės." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050415_101744-92358.
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Milk and dairy products are one of the most prevalent and broadly consumed foodstuffs. Ice-cream occupies an important place in a wide range of dairy products.
The goal of the paper. To analyze the technological process of ice-cream production in the one of the most advanced enterprise UAB Vikeda. To examine the influence of biologically valuable additives on the technological process of the ice-cream production and quality.
Novelty of the paper. Samples of ice-cream have been produced under laboratory conditions of the Technology Laboratory at Lithuanian Food Institute using the following additives: wheat fiber gel Vitacel, acacia gum fiber Fibergum, lupine proteins Lupine protein and Omega-fatty acids. Physical and sensual qualities of the ice-cream have been examined.
Methods of research. Research has been performed in UAB Vikeda located in Kedainiai and in Lithuanian Food Institute.
The following qualities of ice-cream have been analyzed: melting of ice-cream; hardness of ice-cream; sensual evaluation of ice-cream; research of consumers. The melting of ice-cream samples has been determined in accordance with the methods presented by Lithuanian Food Institute. Instrumental research of the hardness of the ice-cream texture has been performed using the semi-automatic penetrometer Labor. Sensual qualities of ice-cream have been evaluated in accordance with the „Methods on Sensual Evaluation of Milk and Dairy Products Sensual Analysis“, worked out by Lithuanian Food Institute... [to full text]
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Ma, Xiaodong. "Lyotropic ion effects in guar gum adsorption on various minerals." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31419.
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Adsorption of guar gum was studied on a number of oxide and clay minerals. The tests were performed as a function of salt concentration and pH from solutions of lithium, sodium, potassium, and cesium chlorides. The four salts allowed an assessment to be made of the significance of lyotropic ion phenomena in controlling the adsorption of the polysaccharide. The results showed that the adsorption of the polymer was independent of pH and acidity/basicity of the minerals. Therefore, no evidence of acid-base type of chemical interactions was observed and hydrogen bonding was suggested as the adsorption mechanism. It was also observed that the adsorption of guar gum on quartz, kaolinite and illite proceeded differently from lithium and sodium chloride solutions in comparison to potassium and cesium chlorides. In contrast, no significant effect of salt type and concentration was observed in guar gum adsorption on titania, hematite, and alumina. It was postulated that the presence or absence of an extensive hydration layer at the mineral-solution interface was the dominant factor and that the interfacial water created a barrier against guar gum adsorption. Therefore, the role of ions of a given lyotropic series is to destabilize the interfacial water structure and promote guar gum adsorption. On the other hand, the absence of an extensive hydration layer on titania, alumina, and hematite allowed guar gum to freely interact with the surfaces and thus no lyotropic ion effect was observed. Therefore, lyotropic ion effects are very strong only in the case of strongly hydrated quartz and, apparently, clay minerals. It was also shown that guar gum undergoes extensive aggregation in concentrated solutions of kosmotropic salts (LiCl and NaCl) while chaotropic potassium and cesium chlorides turned out to be very powerful solvents for the polymer. As a result, it can be postulated that individual guar gum molecules adsorb on minerals from concentrated KCl solutions, while entire guar gum aggregates adsorb from concentrated NaCl solutions. Such findings are of particular interest to potash flotation which is carried out in saturated salt solutions. It was stressed that any analysis of the adsorption results using traditional approaches and models must be performed with extreme caution since guar gum solutions are inherently heterogeneous due to the presence of undissolved, colloidal polymer aggregates.Applied Science, Faculty of
Mining Engineering, Keevil Institute of
Graduate
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Yang, Li. "Physicochemical properties of biodegradable/edible films made with gellan gum." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0026/MQ31662.pdf.
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Makonda, Fortunatus B. S. "Gum arabic studies in Tanzania : production, utilization and economic potentials." Thesis, Bangor University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401803.
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Jones, Guy Matthew John. "Rheological properties of gelatin, carrageenan and locust bean gum mixtures." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/11635/.
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This thesis reports data on blends of carrageenan (0.3%w/w) and locust bean gum (0.3%w/w) in the presence of biopolymers, particularly gelatin of varying concentration. Particular attention is given to their behaviour on autoclaving since this is relevant to one of the most important applications of these materials as gelling agents in canned meat products. It was shown there is such 3% gelatin could be found in the gelling system as a result of from collagen in the meat. Gelatin at this level generally reduced the strength of non-autoclaved carrageenan and LBG gels but enhanced autoclaved gels. Studies of turbidity and rheology suggested that the effect was due to phase separation. Investigation of viscosity after autoclaving produced evidence to support the hypothesis that gelatin protected LBG from thermal degradation. For industrial LBG this was not, however, observed by direct molecular weight measurement, although such effects were seen for pure LBG. Interesting differences between the gel strength response between low and high ionic strength buffers were found. It was concluded that textural performance in real products was sensitive to a range of factors (salt, impurities, presence of gelatin) and would be interpreted by a combination of degradation and phase separation theory. Implications for the industry are discussed.
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Masmas, Ahmad Ben Ahmad Salem. "Gum arabic and constituent sugars studied by electron spin resonance." Thesis, Brunel University, 1991. http://bura.brunel.ac.uk/handle/2438/7869.
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Menzies, Alan Robert. "Characterisation of gum arabic using physical, chemical and immunochemical techniques." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357114.
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Boroson, Michael L. (Michael Louis). "Secondary reactions of tars from pyrolysis of sweet gum hardwood." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14859.
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E, Xinyi. "Hemicellulose fiber gum from distillers grain: isolation, structure and properties." Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/4618.
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Master of ScienceDepartment of Grain Science and Industry
Yong Cheng Shi
Isolation of hemicellulose from distillers dry grain with solubles (DDGS) was investigated. Hemicellulose fiber gum (HFG) is a mixture of hemicelluose, protein, ash and starch. It was extracted from a commercial DDGS by heating with or without alkali. Three extraction methods (water heating, alkaline heating and alkaline hydrogen peroxide heating) were evaluated. Yield of HFG and the recovery of hemicellulose were obtained. High heating temperature (100 and 120°C), alkali or hydrogen peroxide facilitated the release of hemicellulose from the cell wall matrix. However combining alkali with 2.5% H2O2 did not extract more hemicellulose out than did alkali alone. The highest hemicellulose recovery was 32% achieved by cooking at 120°C with 2% alkaline solution. Hemicellulose can function as an emulsifier in the oil-in-water emulsions, such as beverage, and potentially replace gum arabic. HFGs obtained by a series of extracting methods were applied in both the concentrated emulsion with the gum: oil: water ratio of 0.5:1: 8.5 and the diluted emulsion with the gum: oil: water ratio of 0.005: 0.01: 1. The emulsion stability was evaluated by turbidity and creaming test. HFG extracted by 2% NaOH solution at 120°C and HFG extracted by 2% NaOH and 2.5% H2O2 solution at 100°C showed the best emulsifying ability among 15 HFG samples. DDGS was produced from corn, sorghum, wheat in the lab. HFGs extracted from sorghum and wheat DDGS were compared with that from corn DDGS. The composition of the three DDGS varied in protein, fat and non-starch carbohydrate contents. Sorghum and wheat DDGS contained higher levels of protein and lower levels of fat and non-starch carbohydrate than corn DDGS. HFG was extracted by 2% NaOH solution at 100°C for one hour and purified by 100% ethanol. The yield of HFG from corn, sorghum and wheat DDGS was 21.08, 11.07, 11.64% respectively, while the hemicellulose recovery was 30.95, 29.74, 22.71% respectively. The water extractable hemicelluloses from all three DDGS had similar ratios of arabinose to xylose.
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Tsiami, Amalia A. "Physiochemical properties of Gellan gum in gel and solution state." Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358455.
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Nelson, Kristen Marie. "EVALUATING THE MYTH OF ALLELOPATHY IN CALIFORNIA BLUE GUM PLANTATIONS." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1643.
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It is widely accepted that allelopathy is not only significant, but more or less singular, in the inhibition of understory vegetation in California Eucalyptus globulus (blue gum) plantations. However, there is no published documentation of allelopathy by blue gums against California native species. Here, we present evidence that germination and early seedling growth of five California native species are not inhibited by chemical extracts of blue gum foliage, either at naturally-occurring or artificially concentrated levels. In the greenhouse, seeds were germinated in field-collected soil from mature blue gum plantations and the adjacent native, coastal scrub communities. In petri plates, seeds of native species were germinated in the presence of concentrated volatile and water-soluble compounds from fresh foliage of blue gum, coast live oak (Quercus agrifolia) as a negative control, or white sage (Salvia apiana) as a positive control, or in a water control. In the greenhouse, blue gum soil supported germination and early seedling growth of native species equal to or better than coastal scrub soil. In the lab, germination of native species was not inhibited when grown in the presence of volatile compounds from blue gum foliage, compared to the native control (coast live oak) or the neutral water control. Germination of three out of five native species tested was not inhibited in the presence of water-soluble compounds from blue gum foliage, compared to coast live oak or the water control. Our results contradict the long-standing paradigm that blue gums are toxic to California natives, which may have significant implications for management and restoration of land historically occupied by blue gum plantations.
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Uilaighlets, G. "An gum and literary translation 1926-1956 : a study of three significant writers/An gum agus an tAistriuchan literartha 1926-1956: staidear ar thriur scribhneoiri iomraiteacha." Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546435.
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Creel, Rachel Elaine. "Effects of acacia gum on post-harvest qualit of cut flowers." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Summer/Theses/CREEL_RACHEL_5.pdf.
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Ormsby, Bronwyn Ann. "The materials and techniques of William Blake's tempera paintings : William Blake, 1757-1827." Thesis, Northumbria University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275737.
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