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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.
251

Ein Doppelschneckenextruder zur Materialdosierung in einem Rapid Prototyping-Prozess

Flath, Tobias, Schulze, Fritz Peter, Neunzehn, Jörg, Wiesmann, Hans-Peter, Hacker, Michael C., Schulz-Siegmund, Michaela January 2016 (has links)
Aus der Einleitung: "Im Tissue Engineering und in der Medizintechnik gewinnt das Rapid Prototyping (RP), das zu den additiven Fertigungsverfahren zählt, zunehmend an Bedeutung (Zhang, et al. 2015) (Li, et al. 2014). Für die Verarbeitung von thermoplastischen Biopolymeren ist das Fused Deposition Modeling (FDM, schematische Darstellung in Abbildung 1) von zentralem Stellenwert. ..."
252

[pt] CARACTERIZAÇÃO DO CARBONO BIOPOLIMÉRICO SEDIMENTAR EM ESCALA REGIONAL NA BACIA DE SANTOS / [en] CHARACTERIZATION OF SEDIMENTARY BIOPOLYMERIC CARBON ON A REGIONAL SCALE IN THE SANTOS BASIN

10 February 2022 (has links)
[pt] As plataformas continentais são grandes reservatórios de matéria orgânica, reflexo das altas taxas de produção primária e do aporte continental nessas províncias dos oceanos. O sedimento de fundo é um depósito natural para matéria orgânica e para diferentes tipos de poluentes. A composição bioquímica da matéria orgânica sedimentar permite identificar a sua origem e qualidade como alimento para organismos bentônicos heterotróficos. Deste modo, esta pesquisa teve como objetivo avaliar a qualidade nutricional da matéria orgânica sedimentar superficial da Bacia de Santos, localizada entre Cabo Frio (RJ) e o Cabo de Santa Marta (SC) através do teor de carbono biopolimérico, que representa a soma de carboidratos, proteínas e lipídios totais. Para isso, foram realizadas amostragens em 87 estações de coleta, em triplicata. Os biopolímeros orgânicos (proteínas, carboidratos e lipídeos totais) foram analisados separadamente após extração/digestão e medição por espectrofotometria de absorção molecular. Para carboidratos (CHO) obteve-se média de 1,23 ± 0,36 mgC g-1 de sedimento seco, para proteínas (PRT) esse valor foi de 1,06 ± 0,31 mgC g-1 de sedimento seco e para lipídios (LIP) a média foi de 0,32 ± 0,11 mgC g-1. O carbono biopolimérico (CBP) é resultado da transformação dos valores obtidos para os biopolímeros em equivalentes de carbono através de fatores de conversão. Para esse parâmetro obteve-se média de 2,63 ± 0,53 mgC g-1. O índice alimentar (IA) calculado para a matéria orgânica no sedimento apresentou valores que variaram de 28,7 até 65,7 porcento, indicando uma grande contribuição do CBP em relação ao carbono orgânico total. Também foi observada elevada variabilidade espacial do CBP em função da produtividade primária, processos biogeoquímicos e hidrodinâmicos da área. Por fim, a avaliação da qualidade do material orgânico presente no sedimento, feita através do CBP e do IA, indicou alta biodisponibilidade de alimento para os organismos bentônicos, principalmente na plataforma e talude médio. / [en] The continental shelves are large reservoirs of organic matter, reflecting the high rates of primary production and continental input into these ocean provinces. The bottom sediment is a natural repository for organic matter and for different types of pollutants. The biochemical composition of sedimentary organic matter allows us to identify its origin and quality as food for benthic heterotrophic organisms. Thus, this research aimed to evaluate the nutritional quality of the superficial sedimentary organic matter of the Santos Basin, located between Cabo Frio (RJ) and Cabo de Santa Marta (SC) through the biopolymer carbon content, which represents the sum of carbohydrates, proteins and total lipids. For this, sampling was carried out in 87 collection stations, in triplicate. The organic biopolymers (proteins, carbohydrates and total lipids) were analyzed separately after extraction/digestion and measurement by molecular absorption spectrophotometry. For carbohydrates (CHO) an average of 1.23 ± 0.36 mgC g-1 of dry sediment was obtained, for proteins (PRT) this value was 1.06 ± 0.31 mgC g-1 of dry sediment and for lipids (LIP) the average was 0.32 ± 0.11 mgC g-1. The biopolymer carbon (CBP) is the result of the transformation of the values obtained for the biopolymers in carbon equivalents through conversion factors. For this parameter an average of 2.63 ± 0.53 mgC g-1 was obtained. The food index (AI) calculated for organic matter in sediment showed values ranging from 28.7 to 65.7 percent, indicating a large contribution of CBP in relation to total organic carbon. High spatial variability of CBP was also observed as a function of primary productivity, biogeochemical and hydrodynamic processes in the area. Finally, the evaluation of the quality of organic material present in the sediment, through CBP and AI, indicated high bioavailability of food for benthic organisms, mainly in the platform and medium slope.
253

Studium reaktivity biopolymerů v gelové fázi / Reactivity-mapping studies on biopolymers in hydrogel forms

Smilek, Jiří January 2012 (has links)
The diploma thesis is focused on the study of interactions between biopolymers and model probes in a hydrogel media utilizing diffusion processes. The main aim was to test and to optimize selected combination of diffusion methods (diffusion cells and unsteady diffusion) in study of interactions between biopolymers and organic dyes. Anionic (humic acids) and cationic (chitosan) representatives of biopolymers were utilized and methylene blue and methylene orange were used as a reactivity probe in the case of humic acids and chitosan, respectively. Another appreciable part of the work is represented by in-depth characterization of applied biopolymers and hydrogel samples by a wide range of analytical and physico-chemical methods (rheometry, UV-VIS, FT-IR etc.). Besides particular experimental results on studied systems, the diploma thesis provides both theoretical and practical background for subsequent applications of the innovative and full-automated method for reactivity mapping of biopolymers.
254

Material Properties and Aesthetic Qualities of Gels

Mayer, Kerstin 30 June 2022 (has links)
We live in a time of many challenges. The ‘Great Acceleration’ (Steffen et al., 2015) is a trend that can be observed in numerous fields in our world: be it the development of CO2 emissions, the land use or the enormous amount of produced plastics accompanied by massive environmental pollution. This ‘phenomenon’ is obviously directly linked to the way we live and how our society works. To meet these developments, we need to move away from the big, prone concepts that got us here in the first place, and instead build on a variety of dynamic and changing solutions.
255

Mass Spectrometry Techniques for the Characterization of Synthetic Polymers, Biopolymers, Biodegradation Products and Their Interactions

Casiano-Maldonado, Madalis 01 May 2012 (has links)
No description available.
256

Evaluating the feasibility of chitosan as an adhesive for wood laminates and as a matrix for transparent wood / Kan kitosan användas som lim för trälaminat och som matris för transparent trä?

Sakhadeo, Nihar January 2023 (has links)
En av grundpelarna i alla hållbara system är införandet av en cirkulär ekonomi, som främjar återanvändning och återvinning av material. Plast är en av i utmaning i detta avseende på grund av den stora produktionsvolymen variation i sorter och långsamma nedbrytn. Ett förslag till lösning på dessa problem, som det har forskats allt mer om under de senaste decennierna, är att ersätta syntetiska plaster med lämpliga biobaserade alternativ. Detta arbete syftade till att utforska två möjligheter i detta avseende, (1) Transparent trä (TW) och (2) Lim för trä från en förnybar källa.  Utvärderingen av chitosan som ersättning för de syntetiska delarna av dessa material var det primära syftet med denna studie. TW utnyttjar de inneboende önskvärda egenskaperna hos trä och ökar dess användningsområden genom att ändra dess optiska egenskaper, men behöver en impregneringsmatris, som är en syntetisk polymer, för sin tillverkning. I detta arbete studerades variationen av kitosanimpregnering med tryck och torkningsförhållanden. Mikroskopi, gravimetri, kontaktvinkel och dynamisk mekanisk analys användes för att mäta effektiviteten hos de utvecklade metoderna. Alternativ till syntetiska lim för trä och träkompositer behövs på grund av problem med toxicitet. Chitosans användbarhet som lim för trä har dokumenterats i stor utsträckning. Det har dock inte gjorts så mycket arbete med trälaminat, som valdes som en ett sekundärt fokus för detta arbete. Testning av limmet utfördes med hjälp av skjuvmätningar. Resultaten visade att kitosan, istället för att infiltrera trästrukturen, främst deponerades på dess yta och specifika tester för att bestämma laminatets hållfasthet föll utanför ramen för denna studie. / One of the mainstays of any sustainable system is the implementation of a circular economy, which promotes the reuse and recycling of materials. Plastics are one of the most problematic entities in this regard because of the sheer scale of production, their variety, and their recalcitrant nature. A proposed solution to this problem, one which has seen increasing research in the past decades, is replacing synthetic plastics with suitable bio-based alternatives. This work aimed to explore two possibilities in this regard, (1) Transparent wood (TW) and (2) Adhesives for wood. Evaluating the utility of chitosan as a replacement for the synthetic portions of these materials was the primary aim of this study. TW utilizes the inherently desirable properties of wood and increases its avenues of application by changing its optical properties but needs an impregnation matrix, which is a synthetic polymer, for fabrication. This work studied the variation of chitosan impregnation with pressure and drying conditions. Microscopy, gravimetry, water contact angle and dynamic mechanical analysis were used to gauge the efficacy of our methods. Alternatives to synthetic adhesives for wood and wood-composites are needed because of their associated problems with toxicity. Chitosan’s utility as an adhesive for wood has been documented to a considerable extent. However, not much work has been done with wood laminates, which were chosen as a secondary focal point of this work. Adhesive testing was carried out via lap-shear measurements. Results indicated that chitosan, instead of infiltrating the wood structure, was primarily deposited on its surface and specific tests for determining laminate strength fell out of the scope of this study.
257

Sustainable food packaging based on polyhydroxyalkanoate / Hållbara livsmedelsförpackningar baserade på polyhydroxialkanoat

Al-Ashor, Safana January 2024 (has links)
The Norwegian Food Research Institute (Nofima) and the University of Borås worked together to develop this project. The commonly used packaging materials pose a serious threat to the environment, as they are produced from nonrenewable crude oil and cannot decompose naturally. Despite some manufacturers' claims of their products being eco-friendly or sustainable, they are not entirely made from renewable resources and are not biodegradable. Nevertheless, some bio-based materials have emerged as a viable alternative that can naturally break down and safely decompose in the environment. Despite many studies, biopolymers possess limited mechanical and barrier properties, which restricts their potential for use in products. To overcome this limitation, polymer blending can be employed to enhance their final properties and make them more suitable for various applications. The objective of this project was to design sustainable food packaging using biopolymers. PHBV, one of the PHA’s bio-based polymers, was blended with other polymers to enhance its properties as a sustainable food packaging material. Through blending, PHAs'physical, chemical, and thermal properties can be enhanced to obtain exceptional films for food packaging purposes. Finally, in this work, a bio-based polymer, polyhydroxyalkanoate, was used to producea biodegradable packaging system for potential food packaging applications. The effect of the physical modification of PHBV on mechanical and barrier properties was studied by blending it with biodegradable polymers such as PLA and PBAT. Thermal properties were analyzed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and FourierIItransform infrared spectroscopy (FTIR) while the mechanical properties were evaluated by tensile test. Barrier properties were characterized using water vapor transmission rate (WVTR). The mechanical performance of PHBV 50%: PBAT 50% blend has been significantly improved, leading to better tensile properties. The high crystallinity of the PHBV 50%: PBAT 50% blend than other blends have been found to enhance the barrier properties of the polymer film, according to DSC analysis. FTIR investigations have suggested no difference in absorption peaks between the blends and the neat material. Furthermore, WVTR investigations have shown that PHBV50%: PBAT50% exhibits excellent barrier properties against water vapor, making it a highly promising material.
258

Biomimetic Production Techniques for Mechanical and Chemical Characterization of Sucker Ring Teeth Isoform-12 From the Dosidicus Gigas Squid

Grant, Marcus T. January 2016 (has links)
No description available.
259

Dispersed bio-based binders as drop-in solution for non-woven industry / Biobaserade dispersersionsbindemedel som alternativ till nonwovenindustrin

Ingo, Emma January 2021 (has links)
Sammanfattning på svenska: Målet med projektet var att utveckla ett system av disperserade bindemedel för non-wovenindustrin som inte förutsätter omfattande förändringar i befintliga processer. Bindemedlet ska vara biobaserat, bionedbrytbart och endast bestå av byggstenar som är matkontaktsgodkända av FDA och BFR. Ett disperserat system möjliggör en hög torrhalt tillsammans med en låg viskositet som i kombination med stor anpassningsbarhet kan konkurrera med fossila bindemedel på marknaden. Denna studie behandlar användande och modifiering av vattenlösliga biopolymerer för utveckling av ett disperserat system med förmågan att binda samman fibrer i ett non-wovenmaterial. Flertal analytiska metoder och observationer används, som Fourier transform infraröd spektroskopi (FTIR), laddningsdensitet, viskositet och optisk mikroskopi, för att mäta framgången av konceptet. Olika modifieringar och ympningsstrategier användes under projektet och deras inverkan på biopolymerer diskuteras. / The aim of the project was to develop a dispersed binder as a drop-in solution for non-woven industry. The binder should be bio-based, biodegradable and consist only of FDA and BFR food contact approved components. A dispersed system enables the binder to have a high solid content while having a low viscosity. This feature, in combination with a binder with tunable properties, can be a competitive alternative for the fossil-based binders in the market.  This study focuses on the use and modification of biopolymers with binding capacity to form a dispersed system from water-soluble biopolymers. The success of the reaction was evaluated by using a multitude of analytical methods and observation, such as Fourier transform infrared spectroscopy (FTIR), charge distribution and viscosity measurements. Several modification strategies and grafting agents were used and their impact on the biopolymer is discussed.
260

Production of Bio-Based Chemicals and Polymers from Renewable Feedstocks: Bioprocesses Development

Bustamante Jaramillo, Daniel Arturo 29 October 2021 (has links)
Tesis por compendio / [ES] El aprovechamiento de subproductos para producir biocombustibles, energía y compuestos químicos básicos es cada vez más necesario en la situación actual de escasez de petróleo y preocupación por el medioambiente. Muchos compuestos que tradicionalmente han sido producidos a partir del petróleo pueden sintetizarse hoy día de forma biotecnológica empleando recursos renovables. En este contexto, los microorganismos pueden aprovecharse eficazmente como biocatalizadores para llevar a cabo estas transformaciones. Con este tipo de procesos se pueden aprovechar residuos o materias primas renovables para la obtención de productos de interés como bioplásticos de origen microbiano o productos químicos que pueden servir como monómeros para la síntesis de plásticos biodegradables u otro tipo de aplicaciones. La contaminación ambiental causada por los residuos de polímeros sintéticos no biodegradables es un problema en aumento debido a la estabilidad de los compuestos derivados de los combustibles fósiles. En contraste, los bioplásticos pueden obtenerse de fuentes renovables, lo que posibilita el desarrollo de procesos de producción sostenible. En este trabajo de investigación se han estudiado y desarrollado bioprocesos para la producción de polihidroxialkanoatos, 2,3-butanodiol y ácido D-láctico de forma sostenible empleando materias primas renovables como el suero lácteo de quesería, aceite de camelina, glicerina, fracción orgánica de residuos urbanos y residuos de naranja. La caracterización de las materias primas de partida se realizó mediante técnicas de análisis composicional, análisis en HPLC, cromatografía de gases y técnicas espectrofotométricas. Con estos resultados se hizo una selección de cepas bacterianas capaces de sintetizar los productos de interés a partir de los sustratos seleccionados. Una vez seleccionadas las cepas, el trabajo se centró en el desarrollo de los procesos para conseguir buenos rendimientos de fermentación y su escalado. Por lo tanto, este trabajo de investigación aporta conocimientos sobre la identificación y selección de biocatalizadores industriales para el uso de materias primas renovables y residuos industriales para la producción de productos químicos y polímeros de base biológica. Estos estudios allanan el camino para el futuro desarrollo de procesos biotecnológicos sostenibles en el marco de las biorrefinerías y de la bioeconomía circular. / [CA] L'aprofitament de bioproductes per produir biocombustibles, energia i compostos químics bàsics és cada vegada més necessari en la situació actual d'escassetat de petroli i preocupació pel medi ambient. Molts compostos que tradicionalment s'han produït a partir de petroli es poden sintetitzar hui en dia biotecnològicament utilitzant recursos renovables. En aquest context, els microorganismes es poden utilitzar eficaçment com a biocatalitzadors per dur a terme aquestes transformacions. Amb aquest tipus de processos es poden utilitzar residus o matèries primeres renovables per obtenir productes d'interès com bioplàstics d'origen microbià o químics que puguen servir de monòmers per a la síntesi de plàstics biodegradables o altres aplicacions. La contaminació ambiental causada per residus de polímers sintètics no biodegradables és un problema creixent a causa de l'estabilitat dels compostos de combustibles fòssils. Per contra, els bioplàstics es poden obtenir a partir de fonts renovables, permetent el desenvolupament de processos productius sostenibles. En aquest treball de recerca s'han estudiat i desenvolupat bioprocessos per a la producció de polihidroxialcanoats, 2,3-butanodiol i àcid D-làctic de manera sostenible utilitzant matèries primeres renovables com sèrum de llet, oli de camelina, glicerina, fracció orgànica de residus urbans i residus de taronges. La caracterització de matèries primeres inicials es realitza mitjançant tècniques d'anàlisi composicional, anàlisi HPLC, cromatografia de gasos i tècniques espectrofotomètriques. Amb aquests resultats es crea una selecció de soques bacterianes capaç de sintetitzar els productes d'interès dels substrats seleccionats. Una vegada seleccionades les soques, el treball es va centrar en el desenvolupament dels processos per aconseguir uns bons rendiments de fermentació i el seu escalat. Per tant, aquest treball de recerca aporta coneixements sobre la identificació i selecció de biocatalitzadors industrials per a l'ús de matèries primeres renovables i residus industrials per a la producció de productes químics i polímers de base biològica. Aquests estudis amplien el coneixement per al futur desenvolupament de processos biotecnològics sostenibles en el marc de la biorefineria i la bioeconomia circular. / [EN] The use of by-products to produce biofuels, energy and basic chemicals is increasingly necessary in the current situation of oil shortages and environmental concern. Many compounds that have traditionally been produced from oil can now be synthesised in a biotechnological way using renewable resources. In this context, microorganisms can be effectively used as biocatalysts to carry out these transformations. With this type of process, waste streams or renewable raw materials can be used to obtain products of interest such as bioplastics of microbial origin or chemical products that can serve as monomers for the synthesis of biodegradable plastics or other types of applications. Environmental pollution caused by non-biodegradable synthetic polymer waste is a growing problem due to the stability of compounds derived from fossil fuels. In contrast, bioplastics can be obtained from renewable sources, which enables the development of sustainable production processes. In this research work, bioprocesses for the production of polyhydroxyalkanoates, 2,3-butanediol and D-lactic acid using renewable raw materials such as cheese whey, camelina oil, glycerine, organic waste and orange waste were studied and developed. The characterisation of the raw materials was carried out using compositional analysis, HPLC analysis, gas chromatography and spectrophotometric techniques, among others. With these results, a selection of bacterial strains capable of synthesising the products of interest from the selected substrates was made. Once the strains were selected, the work was focused on process development in order to optimize fermentation yields and scale-up. Therefore, this research work provides knowledge on the identification and selection of industrial biocatalysts for the use of renewable feedstocks and industrial wastes for the production of bio-based chemicals and polymers. These studies pave the way for further development of sustainable biotechnological processes in the framework of biorefineries and circular bioeconomy. / Bustamante Jaramillo, DA. (2021). Production of Bio-Based Chemicals and Polymers from Renewable Feedstocks: Bioprocesses Development [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/175819 / Compendio

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