• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 52
  • 41
  • 5
  • 4
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 129
  • 25
  • 20
  • 17
  • 13
  • 12
  • 11
  • 10
  • 10
  • 10
  • 9
  • 8
  • 8
  • 8
  • 8
  • 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.
51

Evaluation of potential for metal/polymer/metal sandwich material as outer panels for trucks

Wendel, Erik January 2019 (has links)
Reducing the weight of the truck vehicle conveys more cargo to be carried by thetrailer. This has a significant impact on the efficiency of the transport lowering both the total cost of cargo moved and the total carbon dioxide emitted. Half of the body in-white weight of a truck is comprised out of panels made out of thin mild forming steel which cannot be made thinner to reduce weight due to the lowered stiffness it would entail. Sandwich materials have a high stiffness to weight ratio and would for the same panel thickness as regular forming steel have a comparable bending stiffness but lowered weight. This master thesis is intended to be a preliminary study for Scania CV AB on sandwich materials and its potential use as lightweight panels in their trucks. With the intention of investigating whether a commercial sandwich material is capable of filling the role as outer panels of a truck, comparative tests regarding significant matters such as forming and painting was made on identically manufactured demonstrators comparing a sandwich material and a regular forming steel material. The tests identified weaknesses in the current manufacturing process for parts of a sandwich material. Such limitations are problems with painting and joining due to isolated cover sheets, forming problems revealing sink marks likely due to different spring back of the material and hemming flaws due to inadequately optimized hemming technique and anisotropy. Now that more knowledge of sandwich materials has been gained, counter measures for these findings can be made in order to take another step towards lowering the weight of the truck and a more efficient way of transporting goods. / Genom att minska vikten på lastbilen frigörs mer last att bäras av släpvagnen. Detta har en betydande inverkan på effektiviteten hos transporten som sänker både den totala kostnaden för transporterad last och de totala koldioxidutsläppen. Hälften aven lastbils rena karossvikt består av paneler gjorda av tunt mjukt formningsstål vilke tinte kan bli tunnare för att minska vikten på grund av den sänkta styvheten som detskulle medföra. Sandwichmaterial har en hög styvhet till viktförhållande och skulle församma paneltjocklek som vanligt formningsstål ha en jämförbar böjstyvhet men sänkt vikt. Denna uppsats är avsedd att vara en preliminär studie för Scania CV AB om sandwichmaterial och dess potentiella användning av lättvitkspaneler i lastbilar.Med avsikt att undersöka huruvida ett kommersiellt sandwichmaterial kan fylla rollen som lastbilens ytterpaneler utfördes jämförande tester med avseende på signifikanta frågor såsom formning och målning på identiskt tillverkade demonstratorer som jämförde ett sandwichmaterial och ett vanligt formningsstål. Testerna identifierade svagheter med materialet samt hur processen behöver anpassas för att kunna använda sandwichmaterialet i rådande tillverkningsprocess. Identifierade problem var bland annat problem med målning och sammanfogning på grund av isolerade ytterskickt i sandwichmaterialet, problem med formning som gav upphov till limdragningar som troligen beror på materialets olika återfjädring samt falsningsfel på grund av otillräckligt optimerad falsteknik och anisotropi. Nu när mer kunskap om sandwichmaterial erhållits kan motåtgärder för de funna resultaten undersökas för att ta ytterligare ett steg mot att sänka lastbilens vikt och därmed få ett effektivare transportmedel.
52

ASSESSMENT OF INTERFACIAL ADHESION IN POLYMER LAMINATED SHEET METALS

Noori, Hadi 11 1900 (has links)
The polymer laminated sheet metal (PLSM) is a layered material which involves a sheet metal substrate, a thin polymer film and an adhesive layer between the film and the substrate. The adhesion properties between the bonded materials are among the most important issues in PLSM forming operations. In this thesis, the main focus has been devoted to characterizing and improving the adhesion properties of the PLSM system for forming applications. Metallic surface roughness evolution and residual stress development in polymer adherends are two consequences of the plastic deformation of the PLSMs. In chapter 2, the effect of these factors on interfacial adhesion strength between metallic substrate and polymer adherend (polymer film with a thin uniform pressure-sensitive adhesive layer on one side) is investigated by devising a new experimental methodology. This methodology is based on two different protocols for preparation of peel sample, one involving pre-straining in uniaxial tension of the metallic substrate prior to lamination and the other involving post-lamination pre-straining of the PLSM. In chapter 3, the peel test results of two different types of PLSMs at different peel speeds are analyzed with two different approaches common in cohesive zone modeling in the literature, namely linear elastic stiffness approach and critical maximum stress approach. The modeling results revealed the significance of the peel speed in determining the interface strength between the adhesive and metallic substrate. In chapter 4, two mechanical treatment techniques of grinding and knurling are implemented to alter the metallic substrate surface roughness before lamination. Peel strength of these samples are investigated at different peel speeds and at different peel loading directions with respect to the grinding and knurling directions. / Thesis / Doctor of Philosophy (PhD) / The polymer laminated sheet metal (PLSM) is a layered material which involves a sheet metal substrate, a thin polymer film and an adhesive layer between the film and the substrate. In this thesis, the main focus has been devoted to characterizing and improving the adhesion properties of the PLSM system for forming applications. A new experimental methodology has been devised for analyzing the effects of deformation-induced surface roughness of metallic substrate and deformation-induced residual stress in polymer adherends on interfacial peel properties of PLSMs. A novel interpretation of the results obtained from rate-independent cohesive zone modeling of peel test has revealed the significance of peel speed in determining the interface strength between the adhesive and the metallic substrate. In another part of this thesis, the effects of two substrate surface alteration techniques, grinding and knurling, on peel properties of PLSMs have been studied.
53

Sanding, Grit Blasting and Plasma Etching: Effect on Surface Composition and Surface Energy of Graphite/Epoxy Composites

Biao, Qi 02 November 2009 (has links)
No description available.
54

Investigation of Adhesive and Electrical Performance of Waterborne Epoxies for Interlayer Dielectric Material

Jackson, Mitchell L. 30 November 1999 (has links)
The primary differences between the solventborne and waterborne epoxy printed circuit board (PCB) impregnating resins arise from the distinct physical compositions and drying characteristics of the polymer solution and the latex emulsion. The presence of residual surfactant from the waterborne epoxy emulsion poses a concern for dielectric performance and adhesive durability. Another problem involves the crystallization of insoluble solid dicyandiamide (DICY), which is significantly different in morphology than that found in solution cast resins. A two-stage drying model was employed to gain a better understanding the drying and coalescence processes. The process of surface DICY crystal formation during the drying of glass prepreg sheet was related to a threshold concentration of the curing agent in the impregnating latex resin formulation. Conditions favoring faster drying lead to the rapid formation of a coalesced skin layer of latex resin, thereby trapping the curing agent in the bulk and reducing the surface deposition of DICY by percolating water. Surfactant is believed to remain concentrated in a receding wet zone until it is driven to the surfaces of the glass fibers upon the completion of drying. The copper foil/laminate interface was evaluated by a 90° peel test as part of two different studies: an analysis of the viscoelastic response of the interface during peel and a study of the thermal durability of the copper/laminate interfacial peel strength. The surfactant acted as a plasticizer to toughen the fiber/matrix interphase, resulting in larger observed peel strengths in the latex resin impregnated materials relative to the solventborne system. Surfactant segregated to the fiber surface during coalescence to form a plasticized fiber/matrix interphase; surfactant migrated into the bulk during postcure to yield a more homogeneously plasticized epoxy matrix. Dielectric measurements of neat resin and laminate materials revealed that the dielectric constants of the model resin-impregnated laminates met the performance criteria for PCB substrates of their class, regardless of surfactant content. Overall, the adhesive performance, adhesive durability, and dielectric properties of PCB systems fabricated with model latex epoxy resin, containing native surfactant (5 wt %), met or exceeded the performance of an equivalent solventborne resin impregnated system. / Ph. D.
55

Inhibiting Listeria monocytogenes, Vibrio parahaemolyticus and Morganella morganii with Aqueous Methanol Extracts of Punica granatum and Galla chinensis

Wu, Jian 08 December 2014 (has links)
Listeria monocytogenes, Vibrio parahaemolyticus and Morganella morganii are closely related to foodborne illnesses caused by the consumption of seafood and ready-to-eat (RTE) food. Traditional Chinese medicines (TCM) have been widely studied as complementary and alternative medicines, and many of them have been verified to have antimicrobial properties. The purpose of this research was to study antimicrobial effects of plant extracts as potential preservatives in seafood products and to identify the primary antimicrobial compounds in plant extracts. Four plants, Pomegranate peel (PP, Punica Granatum L.), Chinese gallnut (CG, Galla chinensis), forsythia fruit (FS, Forsythia suspensa) and Baikal skullcap root (BS, Scutellaria baicalensis) were ground and extracted with 70% methanol, respectively. The extracts were diluted at tested for antimicrobial activities on V. parahaemolyticus, L. monocytogenes and M. morganii both in agar diffusion assay using tryptic soy agar (TSA), and in microdilution assay using tryptic soy broth (TSB). Both CG and PP extracts, with concentrations no lower than 1 mg/ml, significantly inhibited both V. parahaemolyticus and L. monocytogenes (P<0.01) and reduced the bacterial population by up to 4 logs. No significant inhibition was observed with FS and BS extracts, except for BS at 5 mg/ml on V. parahaemolyticus. None of the extracts showed significant inhibition against M. morganii. The antibacterial activities of CG and PP 70% methanol extracts were tested in ground raw tuna and cooked tail-on shrimp. The extracts were mixed in tuna with final concentration at 1.7 mg/ml, and applied as soaking treatments (5 mg/ml) for shrimp. Both CG and PP extracts inhibited V. parahaemolyticus on both food matrices while only CG significantly inhibited L. monocytogenes. The 70% methanol crude extract of CG was analyzed by HPLC and LC-MS. Oligo-galloyl-O-glucose (nGG, n=1-10) are the major compounds in CG. The crude CG extract was fractionated using HPLC and the fractions were collected based on elution time and tested for their antimicrobial activities against V. parahaemolyticus and L. monocytogenes using agar diffusion methods. The fractions containing 3GG-8GG were the most active antimicrobials on both bacteria. / Ph. D.
56

Long-term Durability Characterization and Prediction of a Urethane-based Adhesive

Anderson, Gabriel Donn 11 June 2020 (has links)
Polymeric adhesives play an increasingly critical role in today's engineering designs. When used, adhesively bonded components reduce or eliminate the need for bolted or welded connections. In many cases, this can reduce stress concentrations and weight. With energy dissipating adhesives, noise and vibration reduction are possible, as is the use of unique or complicated designs that could not otherwise be constructed. Adhesive properties however, can vary greatly with time, temperature, and environmental exposure conditions such as moisture. It is therefore critical, to understand the behavior of adhesives over the range of conditions that a bonded component might experience. In this work, the behavior of a urethane-based adhesive was characterized and long-term durability predictions were developed as a result of the data collected. The popular T-peel sample geometry has been used extensively in this study to explore the mechanics of a bonded system and the resulting impact on adhesive durability. The T-peel specimens used, consist of two aluminum sheets or adherends bonded together, with tabs bent back in the shape of a "T" for gripping in a universal load frame. Unlike some other test geometries, T-peel samples are often made with relatively thin adherends that may experience significant plastic deformation during testing. This extraneous energy dissipation greatly complicates the analysis to extract meaningful fracture properties of the adhesive. During testing, the load required to propagate a crack in the adhesive layer is measured at fixed displacement rates. The total system energy can then be partitioned into the energy dissipated within the adhesive (fracture energy), and the energy dissipated through plastic work in bending of the adherends. By performing these tests at different temperatures and rates, the calculated fracture energies span a wide range of possible material behavior. Using the principles of Time Temperature Superposition (TTS), the collected data can be shifted to different times or temperatures. This behavior is well understood in polymer physics, and is made possible with material specific "shift factors". By using the principles of TTS, data collected in in a relatively short experimental window, can be used to accurately predict the behavior of the adhesive in years or even decades. In this work, nearly 200 T-peel samples were tested in four different studies. A preliminary set of unaged specimens was used to develop testing and data analysis methodologies. A second set of unaged samples was tested over a wide range of temperatures and rates, in addition to a third group, subjected to constant moisture and cyclically varying temperature. The final set of specimens, was exposed to 20 separate isothermal aging conditions. The experimental data showed that the 400+ cycles, were insufficient to statistically distinguish these samples from their unaged counterparts. Additionally, samples aged for up to 2000 hours in a dry environment, or 500 hours in a wet environment, showed no reduction in fracture energies in comparison with unaged samples. Specimens aged for more than 500 hours however, were observed to have a significant decrease in fracture energy values. Strong correlations between the thickness of the adhesive layer and estimated fracture energy values were found in this study. As adhesive thickness varied substantially due to manufacturing differences in the specimens tested, new analysis techniques were developed to deal with the variations in adhesive thickness. A MATLAB code based on the ICPeel program, was written to provide a spatial variation of parameters such as adhesive thickness, peel load, and fracture energy. This provided additional insights into the behavior of these T-peel coupons, and prompted the investigation of the Universal Peel Diagram concept. While this diagram was not found to be applicable to the adhesive tested in this study, the analysis indicated that T-peel coupons could be multivalued. That is, a single measured load value does not always describe an adhesive's fracture energy (as is widely believed). Depending on the sample's geometry and material properties, several measured loads could cause debonding. This has potentially far reaching implications on the selection of appropriate T-peel test geometries, as a single measured load is often assumed to correlate to an adhesive's true fracture energy. In this work, both aged and unaged T-peel specimens were tested and the basis of the Universal Peel Diagram investigated. Given sufficient exposure times to moisture, elevated temperatures were found to significantly reduce the amount of energy dissipated in the urethane-based adhesive. Additionally, the Universal Peel Diagram indicated that for some systems, the load required for debond is in fact, multivalued. Therefore, care should be taken when designing a T-peel test configuration to avoid the multivalued regions. / Master of Science / Polymeric adhesives play an increasingly critical role in today's engineering designs. When used, adhesively bonded components reduce or eliminate the need for bolted or welded connections, reducing their weight in the process. With adhesives, noise and vibration reduction are possible, as is the use of unique or complicated designs that could not otherwise be constructed. Adhesive properties, however, can vary greatly with time, temperature, and other environmental exposure conditions such as moisture. It is therefore critical to understand the behavior of adhesives over the range of conditions that a bonded component might experience. In this work, the behavior of a urethane-based adhesive was characterized in order to develop long-term durability predictions. Numerous test methods have been developed to characterize the behavior of adhesively bonded joints. In this work, T-peel specimens were used consisting of two aluminum sheets (the adherends), bonded together with tabs bent back in the shape of a "T" for gripping in a universal load frame. During testing, the load required to propagate a crack in the adhesive layer is measured. An outcome of this measurement and subsequent data analysis is the fracture energy—a measure of the effectiveness of the adhesive in transferring loads. If we perform these tests at different temperatures and loading rates, we can determine fracture energy values which span a wide range of possible material behavior. Using principles from basic polymer physics, the collected data can be shifted to different times or temperatures enabling us to accurately predict the behavior of the adhesive over years or even decades. In this work, nearly 200 T-peel samples were tested in four different studies. A preliminary set of unaged specimens was used to develop testing and data analysis methodologies. Unaged and cyclically (temperature) aged samples were tested over a wide range of temperatures and rates. The fourth set of specimens was subjected to 20 separate isothermal aging conditions and also tested at different temperatures and rates. The experimental data showed that the 400+ temperature cycles were insufficient to damage these samples significantly. Additionally, samples aged for up to 2000 hours in a dry environment, or 500 hours in a wet environment showed no reduction in performance in comparison with unaged samples. Specimens aged for more than 500 hours in a wet environment however, demonstrated a significant decreases in fracture energy values. Strong correlations between the thickness of the adhesive layer and estimated fracture energy values were found in this study, and new analysis techniques were developed to analyze the effect of these thickness variations on the joint performance.
57

Desenvolvimento e estudo de eficácia clínica por métodos instrumentais de bases de uso tópico contendo extrato de soja fermentado / Development and clinical studies using instrumental methods of topical formulations containing fermented soybean extract

Vieira, Rafael Pinto 28 August 2008 (has links)
Máscaras faciais são preparações cosméticas utilizadas desde a Antigüidade e, atualmente, têm seu uso difundido em função de suas características multifuncionais. Dentre os efeitos atribuídos a estas preparações, temos: limpeza profunda; ações tonificante, adstringente, hidratante e tensora na pele e sensação de bem-estar. Podem ser classificadas conforme sua aplicação, componentes ou grau de risco. As máscaras peel off à base de álcool polivinílico são formulações que, após a aplicação e secagem, formam um filme oclusivo sobre a face e, após sua remoção, conferem maciez, limpeza e ação tensora à pele, retirando células mortas do estrato córneo, resíduos e outros materiais depositados. O extrato de soja obtido pela fermentação do leite de soja pelo Bifidobacterium animale possui açúcares, aminoácidos, peptídeos, proteínas e alto teor de isoflavonas na forma livre, quando comparado ao leite não fermentado. Seu uso em formulações cosméticas visa combater os efeitos do envelhecimento cutâneo, propiciando hidratação, efeito tensor e emoliência à pele. Bases cosméticas de máscaras faciais peel off e emulsão óleo em água, acrescidas ou não de extrato de soja fermentado 5% p/p foram avaliadas em estudos de estabilidade física e físico-química em diversas condições de temperatura e períodos de avaliação, visando obter as de melhor desempenho para estudos clínicos. Os resultados indicaram que as preparações aditivadas com o extrato mantiveram-se estáveis quanto às suas características nos testes de estabilidade, não apresentando variações significativas. As preparações foram submetidas aos estudos clínicos em voluntários com o objetivo de avaliar seus efeitos tensor, na hidratação e na perda de água transepidérmica. Os resultados comprovaram que, em um estudo cinético, a base cosmética de máscara facial peel off , contendo ou não o extrato de soja fermentado, não apresentou diferença estatisticamente significativa para as formulações de emulsão quantos à promoção de elasticidade e firmeza à pele e diminuição da perda de água transepidérmica, mas promoveu maior hidratação das camadas superficiais da pele que as preparações de emulsão óleo em água. / Facial masks are used since antiquity and, currently, its use has spread according to their multifunctional characteristics. Among the effects attributed to these preparations there are deep cleaning; invigorating, stringent, moisturizing and tensor actions and well-being sense. They can be classified according to their application, components or risk degree. Peel off facial masks based on polyvinyl alcohol are formulations that form a film on the face after application and drying. After their removal, they cause tenderness, cleaning and tensor action on the skin, removing dead cells of the stratum corneum other materials deposited. Soybean extract obtained from soymilk fermentation by Bifidobacterium animale has sugars, amino acids, peptides, proteins and high levels of free isoflavones, when compared to nonfermented milk. Its use in cosmetic formulations aims to avoid aging effects on skin, providing moisturizing, softness and tensor effect. Peel off facial masks and emulsions oil in water preparations, containing or not fermented soymilk 5% w/w were evaluated in physical and physical-chemistry stability studies in various temperature and time conditions, targeting the best formulations for clinical tests. Results indicated that preparations containing extract remained stable about their characteristics, showed no significant variations. Preparations were submitted to clinical studies in volunteers to evaluate tensor, moisturizing and transepidermal water loss effects. In a short-term study, results confirmed that peel off facial masks formulations, containing or not soybean fermented extract, showed no statistically significant difference in comparison to emulsion formulations on elasticity and firmness promotion and decreasing on transepidermal water loss. However, peel off facial masks provided greater hydration on skin surface layers than the oil in water emulsion preparations.
58

Filmes de desintegração oral produzidos por tape casting - perspectiva para veiculação de compostos ativos extraídos do resíduo industrial de acerola / Oral disintegration films produced by tape casting - perspective for delivery of active compounds extracted from the industrial residue of acerola

Tedesco, Marcela Perozzi 13 July 2018 (has links)
Devido a acidez e sazonalidade da acerola (Malpighia emarginata DC), grande parte da produção do fruto é destinada ao processamento industrial para que sejam comercializados como sucos ou polpas. Esse processamento gera um resíduo que atualmente é descartado ou utilizado em pequenas quantidades como adubo. Apesar de ser subutilizado, o resíduo de acerola apresenta elevada concentração de compostos como vitamina C, fenólicos, antocianinas, flavonoides, proantocianidinas, carotenoides, dentre outros. Nesse contexto, esse trabalho teve como objetivo a extração de compostos ativos desse resíduo industrial e o desenvolvimento de um sistema para veiculação do mesmo, através de filmes de desintegração oral, que são de fácil administração e apresentam rápida disponibilidade. O resíduo de acerola foi seco em estufa de convecção nas temperaturas de 40, 50 e 60° C com velocidade constante de ar (1,6 m/s) e camada fina (6 mm). Os parâmetros dos modelos de Lewis, Henderson & Pabis, Page, Page Modificado e Logaritimico foram ajustados aos dados experimentais de secagem. A variação da atividade antioxidante e de sus principais compostos (flavonoides, proantocianidinas e vitamica C) foi estudada em função do tempo de secagem nas diferentes temperaturas. A melhor condição determinada na secagem (40°C) passou por extração solvente hidroalcoolico 70% (v/v) e foi incorporado nos filmes de desintegração oral (FDOs) produzidos por tape casting utilizando-se hidroxipropilmetilcelulose (HPMC), carboximetilcelulose (CMC) e amido pré gelatinizado como macromoléculas. De um modo geral, os modelos de Lewis, Henderson & Pabis, Page Modificado e Logaritimico demonstraram bom R2 para todas as temperaturas (0,98849-0,99961), mas na maioria dos parâmetros estatísticos, Page foi sutilmente melhor. A temperatura de 40°C foi a melhor condição para secar o resíduo de acerola, pois apresentou melhores resultados para atividade antioxidante por ORAC (176,85 &micro;mol de Trolox/g de resíduo seco), vitamina C (3,03 mg/ g de resíduo seco), flavonoides (637,17&micro;g equivalente de quercitina/ g de resíduo seco) e proantocianidinas totais (26,43 mg equivalente tanino quebracho/ g de resíduo seco). O resíduo seco a 40°C passou por extração solvente hidroalcoolico 70% (v/v) e foi incorporado nos filmes de desintegração oral (FDOs) produzidos por tape casting utilizando-se hidroxipropilmetilcelulose (HPMC), carboximetilcelulose (CMC) e amido pré gelatinizado como macromoléculas. Os filmes apresentaram liberação in vitro máxima em 10 minutos. O filme de CMC demonstrou maior capacidade redutora seguido do amido e HPMC. O filme de amido apresentou baixa tensão na ruptura indicando propriedades mecânicas inferiores aos demais polímeros. O filme de HPMC, apresentou elevada hidrofilicidade e maior redução da capacidade redutora de 38 e 61% na estabilidade em condições normais (25°C, UR 60%) e acelerada (40°C, 75%) por 28 dias. Portanto, os filmes de CMC se adequam as características para produção e comercialização de FDOs. Os resultados desse trabalho podem contribuir para o desenvolvimento de novos produtos secos com alta qualidade, especialmente aqueles que utilizam resíduos industriais e também impulsionar a produção de FDOs em larga escala por tape casting. / Due to the acidity and seasonality of the acerola (Malpighia emarginata DC), much of the fruit production is destined for industrial processing so that they can be commercialized as juices or pulps. This processing generates a residue that is currently discarded or used in small amounts as fertilizer. Despite being underutilized, the acerola residue presents a high concentration of compounds such as vitamin C, phenolics, anthocyanins, flavonoids, proanthocyanidins, carotenoids, among others. In this context, this project aims the extraction of active compounds of industrial residue and development of a vehicle system of those through oral disintegrating films, which are easy to administer, present precise dosage and rapid availability. Acerola residue was dried in a convective oven in temperatures of 40, 50 e 60°C with velocity air constant (1.6 m/s) and thin layer (6 mm). The parameters of the Lewis, Henderson & Pabis, Modified Page and Logarithmic Model parameters were adjusted to the experimental drying data. The variation of antioxidant activity and its main compounds (flavonoids, proanthocyanidins and vitamin C) was studied as a function of drying time at different temperatures. The best condition determined in drying (40°C) was extracted with hydroalcoholic solvent 70% (v/v) and incorporated into the films of oral disintegration (FDOs) produced by tape casting using hydroxypropylmethylcellulose (HPMC), carboxymethylcellulose (CMC) and pregelatinized starch as macromolecules. In general, the Lewis, Henderson & Pabis, Modified Page and Logarithmic models demonstrated good R2 for all temperatures (0.94949-0.99961), but for most statistical parameters, Page was subtly better. The temperature of 40°C was the best condition to dry acerola residue since it showed best results for antioxidante activity by ORAC (176.85 &micro;mol de Trolox/g dry matter), vitamin C (3.03 mg/g dry matter), flavonoids (637.17 &micro;g quercitin equivalent/g dry matter) and proantocianidins totais (26.43 mg tannin quebracho equivalent/g dry matter). The films showed maximum in vitro release in 10 minutes. The CMC film demonstrated higher reducing capacity followed by starch and HPMC. In the characterization, starch films showed low tensile strength. HPMC films showed good hydrophilicity but greater reduction of 38 and 61% in stability under normal (25°C, 60% RH) and accelerated (40°C, 75%) conditions for 28 days. The results of this work can contribute to the development of new high quality dry products, especially those that use industrial waste, as well as to boost the production of large-scale FDOs by tape casting.
59

Influência dos substratos no desenvolvimento de mudas de plantas frutíferas / Influence of the substrate on the development of fruit plants seedlings

Suguino, Eduardo 14 December 2006 (has links)
No território brasileiro existe uma grande quantidade de plantas frutíferas com potencial de comercialização, por causa de suas propriedades medicinais, como elevados teores de vitamina C e suas propriedades adstringentes. Frutíferas como as da família mirtácea: cabeludinha (Plinia glomerata Berg.), grumixama (Eugenia brasiliensis Lam.), surinam cherry (Eugenia uniflora), uvaia (Eugenia pyriformis Cambess) and camu-camu (Myrciaria dubia (H.B.K.) McVaugh), e também a lichia (Litchi chinensis Sonn.) da família sapindácea, são candidatas a se tornarem uma cultura economicamente importante, porém é necessário melhorar as condições para o desenvolvimento destas plantas. O aumento no uso do substrato, incluindo uma ampla variedade de materiais em sua formulação, favorecem as condições físicas, biológicas e químicas do meio , para um ótimo desenvolvimento. Dessa maneira, o objetivo deste trabalho foi avaliar a influência de diferentes misturas do substrato de casca de pínus, no desenvolvimento de mudas de plantas frutíferas. Utilizou-se o delineamento estatístico em blocos inteiramente ao acaso, com medidas repetidas no tempo, onde cada bloco (localização das bandejas de poliestireno expandido na estufa) era composto de 72 células, com 06 tratamentos (T1 = 100% material original (casca de pínus); T2 = 100% casca de pínus &#8804;0,1mm (partículas pequenas); T3 = 75% casca de pínus &#8804;0,1mm + 25% casca de pínus 0,1 - 4,0mm (partículas grandes); T4 = 50% casca de pínus &#8804;0,1mm + 50% casca de pínus 0,1 - 4,0mm; T5 = 25% casca de pínus &#8804;0,1mm + 75% casca de pínus 0,1 - 4,0mm; T6 = 100% casca de pínus 0,1-0,4mm) e 12 sementes em cada unidade experimental e com 5 repetições, perfazendo um total de 360 plantas, para cada espécie. Foram realizadas 3 avaliações para cada espécie utilizada, sendo a primeira realizada após três meses da semeadura, seguidas de duas avaliações mensais. Os dados obtidos foram analisados pelo programa estatístico SAS (2003). O aumento na proporção de partículas pequenas nos tratamentos diminui a taxa de germinação das sementes, pois a textura dessa classe granulométrica de substrato dificulta a absorção de água nos primeiros dias após a semeadura e prejudica a aeração para as raízes, após a quebra da tensão superficial. Este experimento mostrou que os substratos influem diretamente no desenvolvimento de mudas de plantas frutíferas. / In the Brazilian territory there are a great amount of fruti plants with commercialization potential because of their properties for use as medicinal plants, presenting high vitamin C content and astringent properties. Fruit plants such as those from myrtaceae family: cabeludinha (Plinia glomerata Berg.), grumixama (Eugenia brasiliensis Lam.), surinam cherry (Eugenia uniflora), uvaia (Eugenia pyriformis Cambess) and camu-camu (Myrciaria dubia (H.B.K.) McVaugh), and also the lichia (Litchi chinensis Sonn.) from sapindaceae family, are candidates to become economically important cultures, however, there is need for development of optimal conditions for development of those plants. An increment of the substrate usage, including a wide variety of materials in its formulation, has resulted in conditions that favor physical, chemical and biological means for optimal plant development. Therefore, the objective of this study was evaluate, the influence of the different mixture of the substrate made of pinus peel, in the development of seedlings of fruit plants. It was used the completely randomized blocks design, with repeated measures in the time, where each block (location of trays of expanded polystyrene in the greenhouse) was composed of 72 cells, with 06 treatments (T1 = 100% original material of pinus peel); T2 = 100% pinus peel &#8804;0,1mm (small particles)); T3 = 75% pinus peel &#8804;0,1mm + 25% pinus peel 0,1 - 4,0mm (big particles); T4 = 50% pinus peel &#8804;0,1mm + 50% pinus peel 0,1 - 4,0mm; T5 = 25% pinus peel &#8804;0,1mm + 75% pinus peel 0,1 - 4,0mm; T6 = 100% pinus peel 0,1- 0,4mm) and 12 seeds in each experimental unit, with 5 repetitions, doing a total of 360 plants, of each species. Three evaluations were accomplished for each species, being the first accomplished being after three months of the sowing, followed by two monthly evaluations thereafter. The obtained data were analyzed by the SAS statistical program (2003). The increase in the proportion of small particles into the substrate reduces the germination rate, because the fine texture of pinus peel hinders root water absorption and aeration in the initial days after sowing, after the breakage of the superficial tension. This experiment showed that the substrate influence directly on the developing of seedlings of the fruit plants.
60

Resíduo de cebola (Allium cepa L.) como conservante natural em carne / Waste of onion (Allium cepa l.) as a natural preservative in meat

Santana, Antônio Thiago Matos Carvalho 05 December 2014 (has links)
A produção de resíduos pelas indústrias alimentícias têm se tornado um problema ambiental. Esses subprodutos sem o devido descarte se acumulam no meio ambiente causando poluição que leva a contaminações que podem provocar danos ao organismo humano. A sustentabilidade deve ser prioritária para o setor de processamento alimentício, realizando o aproveitamento de qualquer despejo industrial que possa se transformar em foco de contaminação ambiental. A cebola (Allium cepa L.) é um dos vegetais mais consumidos mundialmente, e em consequência disso, seu processamento gera uma grande quantidade de resíduos. A casca desse alimento apresenta teores consideráveis de flavonoides, compostos bioativos de elevada capacidade antioxidante. A transformação desse resíduo em um produto de fácil utilização e que possa agregar valor à matrizes alimentares torna-se uma alternativa para utilização desse resíduo que até então não apresenta um aproveitamento valioso para o setor alimentício. Três variedades de casca de cebola foram processadas na forma de pós e analisadas quanto a sua composição química e quanto à sua ação antioxidante. O produto elaborado que apresentou maior capacidade antioxidante foi o pó de casca de cebola roxa que em seguida foi adicionado ao produto cárneo de frango para avaliar seu potencial frente à oxidação lipídica. Houve o controle na estabilidade oxidativa do produto, porém a adição do conservante natural alterou os parâmetros de cor das almôndegas de frango, tornando mais escura a coloração do produto. Diante do exposto, a elaboração do produto a partir do resíduo da cebola pode se constituir em uma alternativa viável aos produtos sintéticos utilizados para fins da conservação em produtos cárneos uma vez que mostrou-se um potencial antioxidante. / Waste production by food industries have become a serious environmental problem. These by-products without proper disposal may accumulate in the environment causing pollution or contamination that may cause damage to the human body. Sustainability should be a priority in processing food sector, realizing use of any industrial dump it can become the focus of environmental contamination. The onion (Allium cepa l.) is one of the most consumed vegetable worldwide, and as a consequence, its processing generates a large amount of waste. The peel of this food has considerable amounts of flavonoids, bioactive compounds of high antioxidant capacity. The transformation of this waste in an easy-to-use product that can add value to food matrices becomes an alternative to the use of this waste that does not present a valuable use for the food industry. Three varieties of onion peel were processed as into powders and their chemical composition, mainly antioxidant activity were analysed. In the present study, the elaborated product that showed the highest antioxidant capacity was the purple onion peel powder which was added to the meat product processed chicken to assess its potential against lipid oxidation. There was the fat decay control of the product, however the addition of natural preservative caused differences in the color parameters of chicken meatballs, making the darker the color of the product. Therefore, the elaboration of a product from the onion waste was a viable alternative to synthetic products used for conservation purposes in meat products and proved to be a potential antioxidant.

Page generated in 0.0601 seconds