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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.
41

Copper compounds for durable composites : effects on material properties /

Vidrine, Cheney L. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 86-95). Also available on the World Wide Web.
42

Determination of the molecular and physiological basis of citric acid tolerance in spoilage yeast /

McGuire, Lynne. January 2009 (has links)
Thesis (Ph.D.) - University of St Andrews, June 2009.
43

Efeito da resistência natural e tratamentos químicos no lenho juvenil e adulto de Hevea brasiliensis Mull.Arg. ao fungo manchador Botryodiplodia theobromae e cupim Cryptotermes brevis

Coneglian, Ademilson [UNESP] 03 November 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:31:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-11-03Bitstream added on 2014-06-13T21:02:45Z : No. of bitstreams: 1 coneglian_a_dr_botfca.pdf: 1237650 bytes, checksum: d12b91faed872644734eee6e3530ea7b (MD5) / No Brasil a exploração e a utilização da madeira de Hevea brasiliensis Mull Arg., no final do ciclo produtivo de látex de 30 a 35 anos, é praticamente desconhecida. Contudo, um dos problemas mais sérios relacionados à sua utilização diz respeito à alta susceptilibilidade da madeira ao ataque de fungos manchadores e insetos, notadamente na fase entre o corte e o processamento primário. Portanto, a adoção de medidas visando à preservação entre os lenhos juvenil e adulto é altamente necessária, garantindo uma maior durabilidade econômica na utilização desse recurso. No presente trabalho foi avaliado o efeito dos ingredientes ativos a base de Quinolinolato de Cobre – 8 e Carbendazim (T1); 2-4-6 Tribromofenol (T2); Extrato vegetal a base de Tanino (T3); Carbendazim e Prochloraz (T4), contra o ataque do fungo manchador Botryodiplodia theobromae em laboratório seguindo a norma ASTM 4445 (2003) e ingredientes ativos a base de Ciflutrina (T5) e Cipermetrina (T6), na avaliação de infestação do cupim de madeira seca Cryptotermes brevis em madeira de Hevea brasiliensis, seguindo a norma IPT – 1157 (1980) e ASTM 3345 (1990). Os resultados mostraram que os ingredientes ativos testados e avaliados isoladamente em laboratório o T1, T2, T3 e T4, não previnem na totalidade a contaminação do Botryodiplodia theobromae nos Lenhos Juvenil e Adulto da madeira de Hevea brasiliensis ao nível de 5% de significânca, e que a velocidade de penetração do fungo manchador difere nos Lenhos Juvenil e Adulto e entre as Secções Transversal, Radial e Longitudinal da madeira. De posse destes resultados, foi estabelecido um modelo que melhor se ajustou estatísticamente foi o não linear do tipo exponencial (Growth 1). Das interações avaliadas na prevenção ao ataque de cupim de madeira seca Cryptotermes brevis... / In Brazil the exploration and use of the Hevea brasiliensis Mull Arg. wood at the end of the latex production cycle from 30 to 35 years, is practically unknown. However, one of the most significant problems with its use relates to the highly susceptable wood staining fungi and insects, especially in the phase between the primary processing and cutting. The adoption of measures aimed at preserving the trunks between juvenile and adult is highly necessary, ensuring a greater durability in the economic use of this feature. The present study evaluated the effect of the active ingredients of the base Quinolinolato Copper - 8 and Carbendazim (T1); Tribromofenol 2-4-6 (T2); extract-based vegetable Tannin (T3); Carbendazim and Prochloraz (T4), against the attack of the fungus stainer Botryodiplodia theobromae standard ASTM 4445 (2003) and active ingredients the basis of Cypermethrin (T5) and Cyfluthrin (T6) in the evaluation of infestation of the dry wood termite Cryptotermes brevis wood of Hevea brasiliensis standard IPT-1157 (1980) and ASTM 3345 (1990). The results showed that the active ingredients separately tested and evaluated in the laboratory; T1, T2, T3 and T4, will not prevent the total contamination of Botryodiplodia theobromae Firewood in juvenile and adult wood of Hevea brasiliensis the 5% level of significance. The rate of the Firewood in juvenile and adult wood differ when it comes to the stainer's rate of penetration between the transverse, radial and longitudinal timber of Hevea brasiliensis as a function of time. Armed with these results, the non-linear exponential (Growth 1). Interactions evaluated in preventing the attack of dry wood termite Cryptotermes brevis, the two active ingredients the basis of Cypermethrin and Cyfluthrin demonstrated effective in the evaluation of different juvenile... ... (Complete abstract click electronic access below)
44

Estudo da eficiência da lactoferrina como conservante em formulações semi-sólidas para produtos cosméticos e farmacêuticos / Study of the efficiency of the lactoferrin as a preservative in semi-solid formulations for cosmetics and pharmaceutical products.

Marise Conceição Bastos Stevanato 14 February 2006 (has links)
A lactoferrina bovina, descoberta em 1939, é uma glicoproteína que se liga reversivelmente a dois íons férricos, sendo capaz de seqüestrá-los de certos patógenos ou do meio, promovendo redução do crescimento microbiano ou se ligar as suas paredes celulares resultando na permeabilização. A lactoferrina vem ganhando notoriedade nas pesquisas, pois investigações têm descrito sua atividade in vitro frente a diversos microrganismos. Em razão desta propriedade, a mesma poderia ter aplicação nas indústrias cosmética e alimentícia, como um conservante natural. Embora alguns conservantes já estejam consagrados na literatura, os mesmos têm sido relacionados com o desencadeamento de reações alérgicas e de sensibilização, motivando a procura do conservante ideal. O objetivo deste trabalho foi avaliar a utilização da lactoferrina como conservante em formulações semi-sólidas tópicas para usos cosmético e farmacêutico, bem como verificar as estabilidades física e físico-química. Com esta finalidade, três diferentes concentrações de lactoferrina foram incorporadas nos cremes não-iônico e aniônico, gel e gel-creme. A atividade da lactoferrina foi avaliada através do teste de eficácia conservante, sendo que as formulações foram contaminadas com concentrações conhecidas dos microrganismos Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans e Aspergillus niger, com posterior contagem do número de Unidades Formadoras de Colônias (UFC), em placas de Petri, nos tempos zero, 2, 4, 6, 12, 24, 48 e 72 horas, bem como em 7, 14, 21 e 28 dias. Para estudo das estabilidades, as formulações foram avaliadas nos tempos zero, 15, 30, 60, 90, 150 e 180 dias, nas temperaturas de 4°, 25° e 40°C. A estabilidade físico-química foi avaliada através das características macroscópicas, estabilidade à centrifugação, pH, densidade e consistência. A estabilidade física, por meio da determinação da viscosidade e comportamento reológico. Os resultados obtidos, nas condições experimentais deste trabalho, permitiram inferir que a lactoferrina bovina não provocou alteração significativa nas estabilidades física e físico-química das formulações estudadas. Quanto à eficácia da lactoferrina, a mesma não pode ser classificada como substância dotada de atividade conservante, pois não atendeu às exigências preconizadas em compêndios oficiais, frente aos microrganismos estudados. Mesmo não tendo atendido às exigências oficiais como conservante, mostrou-se efetiva frente à levedura Candida albicans, nas formulações do creme não-iônico e gel de hidroxietilcelulose. No entanto, estudos posteriores poderão avaliar a associação da lactoferrina a outros conservantes, buscando sinergismo entre eles, conseqüentemente, podendo diminuir as reações adversas e sensibilizações no usuário. / The bovine lactoferrin, discovered in 1939, is a glycoprotein that connects itself reversibly to two ions of iron being able to kidnap them from certain pathogens or from the environment promoting reduction of the microbial growth or, resulting in permeability if connected to its cellular walls. Lactoferrin has become important in researches because investigations have described its activity in vitro before many microorganisms. Due to this property, lactoferrin could be applied in cosmetic and food industries as a natural preservative. Even though some preservatives are already acclaimed in literature, lactoferrin has been related to the unleashing of allergic reactions and sensibility, motivating the search for the preservative. The goal of this paper was to evaluate lactoferrin as a preservative in semi-solid topic formulations for cosmetic and pharmaceutical uses as to verify the physical and physical-chemical stabilities. On this purpose, three different lactoferrin concentrations were incorporated in non-ionic and anionic creams, gel and gel-cream. Lactoferrin\'s performance was evaluated through testing the efficiency of the preservative, being that the formulations were contaminated by known concentrations of the microorganisms Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans e Aspergillus niger, with posterior counting of the number of Former Colony Units (FCT), in Petri plates, on times zero, 2, 4, 6, 12, 24, 48 and 72 hours, as well as 7, 14, 21, 15, 30, 60, 90, 150 and 180 days, in temperatures of 4º, 25º and 40ºC. The physical-chemical stability was evaluated through the macroscopic characteristics,stability to centrifugation, pH, density and consistency. The physical stability through the determination of viscosity and reologic behavior. The results, in the experimental conditions of this paper, allowed inferring that the bovine lactoferrin didnt\'s provoke significant alteration in the physical and physical-chemical stabilities in the studied formulations. As to the efficiency of lactoferrin, it canot be classified as a substance endowed with preservative activity because it didn\'t reach the extolled demands in official compendiums before the studied microorganisms. Although it didn’t reach the official demands as a preservative, lactoferrin showed itself effective before the yeast Candida albicans on the formulations of the non-ionic cream and hidroxiethyl celulose gel. However, posterior studies will be able to evaluate the association of lactoferrin to other preservatives, seeking synergism between them, being able to consequently diminish the adverse reactions and sensibilities in the user.
45

Oleoresina de capsaicina como preservante natural de madeira de Pinus sp. contra a ação de fungos de podridão branca e de podridão mole / Capsaicin oleoresin as a natural preservative of Pinus sp. wood against the action of white rot and soft rot fungi

Analine Crespo Ziglio 08 May 2015 (has links)
Neste trabalho, avaliou-se a eficácia do uso da oleoresina de capsaicina, extraído das pimentas Malagueta, Red Savina e Bhut Jolokia, no tratamento da superfície de madeiras do gênero Pinus sp. com teores de umidade de equilíbrio de 12% e 0%. Os corpos de prova foram submetidos ao ataque de fungos Paecilomyces variotti e Pycnoporus sanguineus. Foi utilizado um preservante sintético conhecido comercialmente como stain para se comparar com a eficiência de preservantes naturais à base de oleoresina de capsaicina. A partir de medidas de ângulo de contato das superfícies das madeiras tratadas com o óleo de capsaicina, observou-se que a pimenta Bhut Jolokia e o preservante stain proporcionavam menor molhabilidade para a espécie de madeira estudada em ambos teores de umidade. O tratamento preservante fez com que a energia de superfície diminuísse se comparada aos valores de amostras de madeiras sem o tratamento preservante devido às contribuições polares e dispersivas. A análise estatística dos resultados, pelo método de Tukey, mostrou que não existe um grupo de resultados estatisticamente equivalente aos obtidos com a amostra testemunha (sem tratamento). As amostras de Pinus sp. a um teor de umidade 0% mostrou-se mais protegida superficialmente quando modificada com a oleoresina extraída da pimenta Bhut Jolokia e o mesmo efeito foi observado estatisticamente para o preservante stain. A técnica de Langmuir foi utilizada para melhor compreender as interações capsaicina/ergosterol, capsaicina/DPPG (dipalmitoil fosfatidil glicerol) e capsaicina/DPPG/ergosterol. A isotermas de pressão de superfície vs área por molécula se mostraram mais expandidas quando a subfase continha oleoresina de capsacina e quando comparada com as de lipídio puro (DPPG), indicando assim, a inserção da capsaicina na monocamada. Em linhas gerais, oleoresina de capsaicina extraída da pimenta Bhut Jolokia mostrou-se mais eficiente em todos os aspectos se comparada com as pimentas Red Savina e Malagueta, marcando, assim, uma potencialidade para uso como preservante natural de madeiras. / The present study evaluated the effectiveness of capsaicin oleoresin extracted from Malagueta, Red Savina and Bhut Jolokia peppers in the surface treatment of Pinus sp. with moisture contents of 12% and 0%. The samples were submitted to the attack of Paecilomyces variotti and Pycnoporus sanguineus fungus. A synthetic wood preservative, that is commercially known as stain, was used to compare the effectiveness of natural preservatives based on capsaicin oleoresin. From contact angle measurements for wood surfaces treated with capsaicin oleoresin, it was obtained that Bhut Jolokia pepper and stain preservatives have provided worse wettability for wood samples at both moisture contents. The preservative treatment caused a decrease in the surface energy when compared to the samples without preservative treatment due to polar and dispersive contributions. Statistical analysis for the results by using the Tukey method showed that there is not a group of results that are statistically equivalent to those obtained for the control samples (without treatment). Pinus sp. samples at a moisture content of 0% showed to be more surface protected after being modified with the oleoresin extracted from Bhut Jolokia; the same effect was observed statistically for stain. The Langmuir technique was used to better understand interactions among capsaicin/ergosterol, capsaicin/DPPG (dipalmitoyl phosphatidyl glycerol) and capsaicin/DPPG/ergosterol. Surface pressure vs. area per molecule isotherms appeared to be even more extended when the subphase contained capsaicin oleoresin instead of pure lipid (DPPG), thus indicating the inclusion of capsaicin into the monolayer. In general, the capsaicin oleoresin extracted from Bhut Jolokia proved to be more efficient in all the aspects of characterization when compared to Red Savina and Malagueta highlighting its potential for use as a natural wood preservative.
46

Caractérisation des mécanismes d'adaptation d'Enterobacter gergoviae aux conservateurs en cosmétique / characterization of adaptation mechanisms of Enterobacter gergoviae to preservatives in cosmetics

Périamé, Marina 23 September 2014 (has links)
Des contaminations par Enterobacter gergoviae, dans les formulations cosmétiques diverses soulèvent le problème de la résistance bactérienne aux biocides. J'ai pu mettre en évidence, que certains épisodes de contaminations apparus au sein de l'entreprise partenaire, étaient dus à un même isolat persistant suite à un système de conservation/désinfection inefficace. Aux concentrations maximales autorisées par la commission européenne, les conservateurs ont des effets bactériostatiques mais ne présentent pas d'effets synergiques en association. Par conséquent, l'adaptation aux produits cosmétiques est favorisée. Divers mécanismes de résistance peuvent être mis en place par E. gergoviae : enzymatique (synthèse de peroxyredoxine), modifications de l'enveloppe (expression d'appendices externes : flagelles ou fimbriae/pili), modification de la mobilité, et formation de biofilms. L'apparition de ces mécanismes a aussi favorisé les résistances croisées conservateurs /désinfectants-détergents. / Contaminations by Enterobacter gergoviae in various cosmetic formulations raise the problem of bacterial resistance to biocides of the species, which represent the third source of cosmetics bacterial contaminations. The collaborative cosmetic company was concerned by unrelated contaminations but some contamination events were due to persistence of isolates in internal system process, despite disinfection protocols and use of preservatives. At the maximum levels allowed by the European Commission, preservatives tested have bacteriostatic effects and do not exhibit synergistic effects in combination. Therefore, adaptation in cosmetics is facilitated. Various resistance mechanisms can be implemented by E. gergoviae: Enzymatic (peroxyredoxin synthesis), changes in the envelope (expression of external appendages: flagella or fimbriae/pili), changes in mobility and biofilm formation. The appearance of such mechanisms has also promoted a cross-resistance conservative / disinfectant - detergent.
47

Desarrollo de recubrimientos comestibles con actividad antifúngica en frutos cítricos

Valencia Chamorro, Silvia Azucena 22 October 2009 (has links)
En la industria citrícola, las pérdidas económicas más importantes en poscosecha se deben las podredumbres verde y azul, causadas por los hongos Penicillium digitatum (Pers.:Fr.) Sacc. y Penicillium italicum Wehmer. Durante muchos años, se utilizaron ampliamente los fungicidas químicos para el control de estas enfermedades. Sin embargo, la preocupación de los consumidores por el uso excesivo y prolongado de estos productos para el control de las podredumbres ha orientado a los investigadores a buscar métodos alternativos no contaminantes que no depositen residuos peligrosos ni contaminen el ambiente. El uso de películas y recubrimientos comestibles es un método respetuoso con el ambiente que incrementa la vida útil de muchos alimentos incluidas las frutas y verduras. Sin embargo, muy poca investigación se ha enfocado al desarrollo de recubrimientos comestibles compuestos con la adición de compuestos antifúngicos como un nuevo método para controlar las enfermedades poscosecha en frutos cítricos frescos. El objetivo general de esta tesis doctoral fue desarrollar nuevos recubrimientos comestibles compuestos con la adición de aditivos alimentarios antifúngicos para el control de las podredumbres verde y azul en cultivares de cítricos comercialmente importantes. Primero, se desarrollaron las nuevas películas comestibles compuestas en base a hidroxipropil metilcelulosa (HPMC)-lípido con la adición de aditivos alimentarios o compuestos generalmente reconocidos como seguros (GRAS, por sus siglas en inglés), y se seleccionaron de acuerdo a su capacidad de formar emulsiones estables. Las películas se evaluaron por su actividad in vitro contra P. digitatum y P. italicum y sus propiedades mecánicas y de barrera (Capítulo 1). Luego, las emulsiones seleccionadas se usaron para pruebas in vivo en especies y cultivares de cítricos comercialmente importantes y se determinó su actividad antifúngica curativa (fruta recubierta después de la inoculación) y preventiva (fruta recubierta antes de la inoculación fungíca) contra las podredumbres verde y azul (Capítulo 2). / Valencia Chamorro, SA. (2009). Desarrollo de recubrimientos comestibles con actividad antifúngica en frutos cítricos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/6286 / Palancia
48

Qatiy

Bustamante Zúñiga, Angélica Jazmín, Chávez Flores, Valeria Alexandra, Fernández Chevarría, Yuri Alexis Ivan, Santisteban Guerrero, Sheyla Geraldin, Teruya Camt, Julio Eduardo 29 November 2019 (has links)
Lo más importante de nuestro proyecto es la propuesta de valor que ofrece Qatiy; así como la cobertura que brinda a cierto sector del mercado que no se encontraba satisfecho o no contaba con alternativas que cumplieran con sus necesidades. Por ello, es importante resaltar la validación del modelo de negocio; pues, si bien la idea puede ser buena, no necesariamente cumple con las expectativas del consumidor. Por esta razón nuestro producto tuvo que ser evaluado minuciosamente para determinar la viabilidad del consumo para su posterior venta. Otro aspecto determinante se basa en el beneficio que nos brinda en términos financieros; es decir, la alta rentabilidad que podemos obtener tras la puesta en marcha de nuestra empresa. El mercado aún se encuentra en desarrollo y los consumidores cada vez tienen nuevos hábitos y concientización de consumo de productos saludables, lo que significan grandes oportunidades para su explotación. Finalmente, hay que destacar que Qatiy incentiva el consumo de productos hecho a base de alimentos saludables que favorece al bienestar del consumidor, ya que se producen con insumos naturales y sin ningún tipo de preservantes, lo cual es un aporte importante de responsabilidad social por parte de nuestra empresa. / The main thing about our project is the value proposition offered by Qatiy; as well as the coverage it provides to a certain sector of the market that was not satisfied or did not have alternatives meeting their needs. Therefore, it is important to highlight; since, while the idea may be good, it does not necessarily meet consumer expectations. For this reason our product had to be thoroughly evaluated to determine the viability of consumption for subsequent sale. Another determining aspect is based on the benefit it gives us in financial terms; that is the high profitability that we can obtain after the start-up of our company. The market is still in development and consumers are acquiring increasingly new habits and are becoming aware of the benefits of healthy products consumption which means big opportunities for exploitation. Finally, it should be noted that Qatiy encourages the consumption of products made from healthy food that favor the well-being of the consumer, since they are produced with natural supplies and without any preservatives; which is an important contribution of social responsibility by our company. / Trabajo de investigación
49

Stanovení kyseliny propionové v pekařských výrobcích kapalinovou chromatografií / Determination of propionic acid in bakery products by liquid chromatography

Benkovská, Dagmar January 2009 (has links)
This thesis deals with the development of high performance liquid chromatography method (HPLC) for the determination of propionic acid in bakery products. This work is resulting from the requirements and conditions of Czech Agriculture and Food Inspection Authority (CAFIA) laboratory in Brno. The theoretical part of the thesis describes properties, production, metabolism, toxicity and preservative effect of propionic acid. Furthermore it is treating about HPLC, validation of some analytical method and methods of propionic acid determination. Experimental part is focused on the propionic acid determination in the major part of available products with this preservative on the Czech market. Propionic acid was extracted from the sample with water, filtered and the filtrate was analyzed directly by HPLC. Separation was performed on a XBridge C18 column (3 x 150 mm, 3,5 µm) with a mobile phase of phosphate buffer (pH adjusted to 2,8) and UV detection at 210 nm. Used method of propionic acid isolation was compared with repeated extraction method, extraction in the mobile phase solution and steam destilation both in commercial samples and in laboratory baked breads with known addition of propionic acid. HPLC with water extraction technique was evaluated as a suitable method for propionic acid determination in bakery products.
50

Linking the neuropeptide annetocin with reproductive success of the earthworm Eisenia fetida in two natural soils amended with the wood preservatives chromated copper arsenate (CCA) and alkaline copper quaternary (ACQ)

Leduc, Frédéric January 2004 (has links)
No description available.

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