• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 691
  • 275
  • 108
  • 105
  • 97
  • 62
  • 43
  • 28
  • 25
  • 22
  • 17
  • 17
  • 17
  • 17
  • 17
  • Tagged with
  • 1890
  • 244
  • 232
  • 203
  • 202
  • 178
  • 140
  • 140
  • 130
  • 123
  • 102
  • 89
  • 87
  • 82
  • 79
  • 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.
151

Child resistant drug packaging and arthritis can older consumers access their medications? /

Kou, Eric Yao-Chung. January 2006 (has links)
Thesis (M.S.)--Michigan State University. School of Packaging, 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references (p. 161-164). Also issued in print.
152

Drop impact reliability testing lead-free chip scale packages : a thesis /

Farris, Andrew. Liddicoat, Albert A. January 2008 (has links)
Thesis (M.S.)--California Polytechnic State University, 2008. / Major professor: Albert Liddicoat, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Electrical Engineering." "June 2008." Includes bibliographical references (leaves 70-73). Also available online. Also available on microfiche (2 sheets).
153

Produção e caracterização de laminados biodegradáveis e antimicrobianos para embalagens de alimentos

Pizzoli, Ana Paula de Oliveira 23 September 2014 (has links)
Capes; Fundação Araucária / Tendo em vista a crescente demanda por substituição de materiais de embalagens usuais por biodegradáveis bem como pela necessidade da manutenção de segurança dos alimentos durante seu armazenamento, o desenvolvimento de embalagens bioativas biodegradáveis torna-se importante. No presente trabalho foram produzidos laminados compostos por blendas de poli(L-ácido lático) (PLLA), amido termoplástico (TPS) e gelatina por extrusão e calandragem. O processo apresentou-se como uma forma viável para produzir blendas de PLLA / TPS / gelatina com propriedades funcionais interessantes e aspecto homogêneo. A adição de gelatina em diferentes proporções (1, 3 e 5% em relação ao TPS) apresentou diferença significativa nos resultados das análises de solubilidade, permeabilidade ao vapor de água (PVA) e isotermas de sorção de água devido à hidrofilicidade da mesma. Além disso, a incorporação de gelatina na blenda afetou significativamente as propriedades mecânicas através da redução da rigidez associada à incompatibilidade entre PLLA, amido e gelatina, como revelado pelas imagens de microscopia eletrônica de varredura (MEV). Nanopartículas de prata (AgNPs) foram sintetizadas para incorporação aos laminados pela técnica do polissacarídeo modificada, onde nitrato de prata foi reduzido a prata metálica por D-glicose. O diâmetro médio foi determinado através de três técnicas: Espalhamento Dinâmico de Luz (DLS, 63 nm), por Espectrofotômetria UV-Vis (100 nm) e por análise das imagens de MEV (145 nm). Com a análise de FTIR foi possível detectar interações entre os grupamento C=O dos subprodutos de oxidação da D-glicose, produto da reação com o nitrato de prata. As AgNPs apresentaram ação antimicrobiana eficaz contra os microrganismos Bacillus cereus, Staphylococcus aureus, Escherichia coli e Pseudomanas aeruginosa, sendo a Concentração Inibitória Mínima igual a 1,17 µg/ml para E. coli (menor resistência) e 37,50 µg/ml para S. aureus (maior resistência). Os laminados foram tratados superficialmente com a solução resultante da síntese das AgNPs por reticulação enzimática (transglutaminase). Nas imagens de MEV foi possível verificar que os laminados tratados apresentaram maior porosidade em função da umidade promovida pelo tratamento. Através da porosidade criada foram detectadas diferenças significativas nas análises de PVA e propriedades mecânicas. Houve aumento da PVA e redução em todas as propriedades mecânicas, principalmente no módulo de Young em função da criação de pontos de concentração de força. As isotermas apresentaram ajuste adequado ao modelo de GAB (R2>0,99). A atividade antimicrobiana dos laminados contendo AgNPs foi comprovada pela formação de halos de inibição contra os microorganismos descritos anteriormente. Finalmente, os laminados produzidos possuem potencial de aplicação como embalagens ativas com propriedades antimicrobianas e de biodegradação para alimentos. / Due to the growing demand for replacement of the usual packaging materials for biodegradable as well as the need to maintain food safety during storage, the development of bioactive biodegradable packaging becomes important. In this work sheets were produced by extrusion and calendaring process using blends of poly(L-lactic acid) (PLLA), thermoplastic starch (TPS) and gelatin . The process is presented as a viable way to produce blends of PLLA/TPS/gelatin with interesting functional properties and homogeneous appearance. The addition of gelatin in different proportions (1, 3 and 5% related to TPS) showed a significant difference in the solubility test results, the water vapor permeability (WVP) and water sorption isotherms due to gelatin hydrophilicity. Furthermore the incorporation of gelatin in the blend significantly affected the mechanical properties by reducing stiffness associated with incompatibility between PLLA, starch and gelatin, as shown by Scanning Electron Microscopy (SEM) micrographs. Silver nanoparticles (AgNPs) were synthesized for incorporation into the extruded sheets by the modified polysaccharide technique, where silver nitrate is reduced to metallic silver by D-glucose. The average diameter was determined by three techniques: Dynamic light scattering (DLS, 63 nm) by UV-Vis spectrophotometry (100 nm) and by analysis of SEM images (145 nm). With the analysis of FTIR was possible to detect interactions between the C = O groups of D-glucose oxidation byproducts, products of the reaction with silver nitrate. AgNPs presented effective antimicrobial action against the microorganisms: Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, and the Minimum Inhibitory Concentration equal to 1.17 µg/ml for E. coli (lower resistance) and 37.50 µg/ml for S. aureus (greater resistance). The extruded sheets were surface treated with the resulting solution from AgNPs synthesis and enzymatically crosslinked with transglutaminase. At the SEM images it was possible to verify that the treated laminates exhibited higher porosity due to moisture promoted by the treatment. The created porosity influenced significantly the results of the WVP and mechanical properties. There was an increase in vapor permeation and a reduction in all mechanical characteristics, particularly in Young's modulus due to the creation of tension concentration points. The isotherms showed adequate adjustment to GAB model (R2> 0.99). The antimicrobial activity of the laminates containing AgNPs was confirmed by the formation of inhibition zones against the microorganisms described above. Finally, the sheets produced have potential application as active packaging with antimicrobial and biodegradable properties for food.
154

Produção e caracterização de laminados biodegradáveis e antimicrobianos para embalagens de alimentos

Pizzoli, Ana Paula de Oliveira 23 September 2014 (has links)
Capes; Fundação Araucária / Tendo em vista a crescente demanda por substituição de materiais de embalagens usuais por biodegradáveis bem como pela necessidade da manutenção de segurança dos alimentos durante seu armazenamento, o desenvolvimento de embalagens bioativas biodegradáveis torna-se importante. No presente trabalho foram produzidos laminados compostos por blendas de poli(L-ácido lático) (PLLA), amido termoplástico (TPS) e gelatina por extrusão e calandragem. O processo apresentou-se como uma forma viável para produzir blendas de PLLA / TPS / gelatina com propriedades funcionais interessantes e aspecto homogêneo. A adição de gelatina em diferentes proporções (1, 3 e 5% em relação ao TPS) apresentou diferença significativa nos resultados das análises de solubilidade, permeabilidade ao vapor de água (PVA) e isotermas de sorção de água devido à hidrofilicidade da mesma. Além disso, a incorporação de gelatina na blenda afetou significativamente as propriedades mecânicas através da redução da rigidez associada à incompatibilidade entre PLLA, amido e gelatina, como revelado pelas imagens de microscopia eletrônica de varredura (MEV). Nanopartículas de prata (AgNPs) foram sintetizadas para incorporação aos laminados pela técnica do polissacarídeo modificada, onde nitrato de prata foi reduzido a prata metálica por D-glicose. O diâmetro médio foi determinado através de três técnicas: Espalhamento Dinâmico de Luz (DLS, 63 nm), por Espectrofotômetria UV-Vis (100 nm) e por análise das imagens de MEV (145 nm). Com a análise de FTIR foi possível detectar interações entre os grupamento C=O dos subprodutos de oxidação da D-glicose, produto da reação com o nitrato de prata. As AgNPs apresentaram ação antimicrobiana eficaz contra os microrganismos Bacillus cereus, Staphylococcus aureus, Escherichia coli e Pseudomanas aeruginosa, sendo a Concentração Inibitória Mínima igual a 1,17 µg/ml para E. coli (menor resistência) e 37,50 µg/ml para S. aureus (maior resistência). Os laminados foram tratados superficialmente com a solução resultante da síntese das AgNPs por reticulação enzimática (transglutaminase). Nas imagens de MEV foi possível verificar que os laminados tratados apresentaram maior porosidade em função da umidade promovida pelo tratamento. Através da porosidade criada foram detectadas diferenças significativas nas análises de PVA e propriedades mecânicas. Houve aumento da PVA e redução em todas as propriedades mecânicas, principalmente no módulo de Young em função da criação de pontos de concentração de força. As isotermas apresentaram ajuste adequado ao modelo de GAB (R2>0,99). A atividade antimicrobiana dos laminados contendo AgNPs foi comprovada pela formação de halos de inibição contra os microorganismos descritos anteriormente. Finalmente, os laminados produzidos possuem potencial de aplicação como embalagens ativas com propriedades antimicrobianas e de biodegradação para alimentos. / Due to the growing demand for replacement of the usual packaging materials for biodegradable as well as the need to maintain food safety during storage, the development of bioactive biodegradable packaging becomes important. In this work sheets were produced by extrusion and calendaring process using blends of poly(L-lactic acid) (PLLA), thermoplastic starch (TPS) and gelatin . The process is presented as a viable way to produce blends of PLLA/TPS/gelatin with interesting functional properties and homogeneous appearance. The addition of gelatin in different proportions (1, 3 and 5% related to TPS) showed a significant difference in the solubility test results, the water vapor permeability (WVP) and water sorption isotherms due to gelatin hydrophilicity. Furthermore the incorporation of gelatin in the blend significantly affected the mechanical properties by reducing stiffness associated with incompatibility between PLLA, starch and gelatin, as shown by Scanning Electron Microscopy (SEM) micrographs. Silver nanoparticles (AgNPs) were synthesized for incorporation into the extruded sheets by the modified polysaccharide technique, where silver nitrate is reduced to metallic silver by D-glucose. The average diameter was determined by three techniques: Dynamic light scattering (DLS, 63 nm) by UV-Vis spectrophotometry (100 nm) and by analysis of SEM images (145 nm). With the analysis of FTIR was possible to detect interactions between the C = O groups of D-glucose oxidation byproducts, products of the reaction with silver nitrate. AgNPs presented effective antimicrobial action against the microorganisms: Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, and the Minimum Inhibitory Concentration equal to 1.17 µg/ml for E. coli (lower resistance) and 37.50 µg/ml for S. aureus (greater resistance). The extruded sheets were surface treated with the resulting solution from AgNPs synthesis and enzymatically crosslinked with transglutaminase. At the SEM images it was possible to verify that the treated laminates exhibited higher porosity due to moisture promoted by the treatment. The created porosity influenced significantly the results of the WVP and mechanical properties. There was an increase in vapor permeation and a reduction in all mechanical characteristics, particularly in Young's modulus due to the creation of tension concentration points. The isotherms showed adequate adjustment to GAB model (R2> 0.99). The antimicrobial activity of the laminates containing AgNPs was confirmed by the formation of inhibition zones against the microorganisms described above. Finally, the sheets produced have potential application as active packaging with antimicrobial and biodegradable properties for food.
155

Modified atmosphere packaging of ground turkey thigh meat

Sonneville, Beth A. 12 September 2009 (has links)
The objectives of this study were to develop MAP conditions, using mixtures of oxygen (O₂) and carbon dioxide (CO₂), to prolong the shelf-life of ground turkey thigh meat. The effect of fat level and effectiveness of natural antioxidants were evaluated. Product quality was determined semi-weekly by sensory, microbial, chemical, and instrumental analysis to evaluate rancidity, and sensory flavor changes. Thiobarbituric acid (TBA) tests were conducted to objectively measure changes in oxidative rancidity. Microbial analysis included psychrotrophic, lactic acid, and anaerobic bacteria enumerations, pH determinations were conducted to evaluate the effects of each treatment on the meat. Instrumentation color analysis CIE L* a* b* values were determined to measure color changes. Test results indicate the pH changed significantly only in the air packaged samples. Psychrotrophic, lactic acid and anaerobic bacteria counts were significantly lower (P<0.05) in the 100% CO₂ packaged samples, than all other treatments and the control. Low TBA values, less than 4, were found with the 100% CO₂ samples. Sensory evaluation found the 80% O₂/20% CO₂ and 60% O₂/40% CO₂ packages were no longer acceptable at day 14, and air samples were unacceptable at day 18. The 100% CO₂ sample maintained acceptable over-all taste throughout the test period. Colorimeter values did show the 100% CO₂ atmosphere caused discoloration of the product during the first week. Fat level did not affect microorganism growth or shelf-life extension. Rosemary oleoresin was effective as an antioxidant. TBA values of rosemary treated samples remained under 1.0 for the entire 28-day storage period. / Master of Science
156

Att vara ekologisk : En kvalitativ studie om hur konsumenter ser på ekologiska förpackningar

Wikström, Emmie, Sara, Westerlund January 2014 (has links)
Titel: Att vara ekologisk - En kvalitativ studie om hur konsumenter ser på ekologiska förpackningar. Författare: Sara Vesterlund och Emmie Wikström Kurs, termin och år: Kandidatuppsats 15 hp, HT 2014 Handledare: Kent Lövgren Antal ord i uppsatsen: 21 297 Problemformulering och syfte: Det är sedan tidigare konstaterat att förpackningens visuella utformning är ett viktigt marknadsförings- och positioneringsverktyg och används för att kommunicera varumärken. Den visuella utformningen är särskilt viktig på förpackningar till lågengagemangsprodukter då tidigare forskning visat att konsumenter ofta väljer förpackningar baserat på deras utseende. För den växande marknaden är det intressant att se hur förpackningen används för att positionera ekologi och ekologiska produkter och hur konsumenter uppfattar ekologiska förpackningars kommunikation. Vårt syfte är att studera hur förpackningarna till ekologiska produkter används för att visuellt kommunicera ekologi, samt undersöka hur konsumenter uppfattar produktförpackningarnas kommunikation av ekologi. Metod och material: De metoder som användes var kvalitativ innehållsanalys för att undersöka de ekologiska förpackningarna samt fokusgrupper för att undersöka konsumenters uppfattning av ekologiska förpackningar. Huvudresultat: Samtliga förpackningar använder olika visuella element för att framhäva ekologi på förpackningen. De förpackningar som bäst stämde överens med konsumenternas associationer av hur en ekologisk förpackning ser ut var de förpackningar som konsumenterna ansåg kommunicera ekologi tydligast. De element som konsumenterna ansåg kommunicera ekologi bäst var naturfärgade material och gröna och bruna färger, samt typografi i handstil. / Problem definition and purpose: It is well known that the visual design of packages is an important marketing and positioning tool used to communicate brand identity. The visual design is particularly important on the packages of low-involement products and previous research have found that consumers often choose packages based on their apperance. It is interesting for the ever growing market of organic products to see how packages is used in positioning organic products and discover how consumers view the communication on organic packages. The purpose of this study is to analyze how the packages of organic products is used to visually communicate ecology, and investigate how consumers view the communication on the packages of organic products. Method and material: The methods used in this study were qualitative content analysis, which was used to analyze the packages and focus groups, which were used to analyze consumers perception of organic packages. Result: All of the analyzed packages used different visual elements to highlight their organic attributes on the package. The packages that best matched the consumers’ inplanted associations of organic products was the packages that was conveyed to best communicate an organic product. The consumers’ idea of a good visual design for an organic product included handwritten typography, natural-colored material and elements in green and brown colors.
157

A Non-Contact Measurement Technique At The Micro Scale

Ghosh, Santaneel January 2005 (has links)
During their production and normal use, electronic packages experience large temperature excursions, leading to high thermo-mechanical stress gradients that cause fatigue failure of the solder joints. In order to prevent premature failure and prolong the fatigue life of solder joints, there is a pressing need for the characterization of the solder, especially lead-free solder, at the micro-level (joint size). The characterization and modeling of solder behavior at the appropriate scale is a major issue. However, direct measurement techniques are not applicable to characterize the deformation response of solder joints because of their micro scale dimensions. Therefore, a non-contact measurement technique utilizing a Scanning Electron Microscope (SEM) in conjunction with Digital Image Correlation (DIC) has been developed. Validation was achieved by performing a four-point bending test in both an in-house optical system with DIC and inside the SEM. This non-contact measurement technique was then used to extract the stress-strain response of the solder. Mechanical tests were performed on solder joints that were created using the same type of solder balls used in the electronic industry and were representative of normal joint scales. The SEM-DIC technique has been proven to be applicable for the determining the stress-strain response of solder material at the micro-scale.This study resulted in a validated material characterization technique specifically designed for micro-scale material response. One of the main contributions of this study is that the method is a lot simpler and cheaper, yet highly effective, compared to the previous methods. This technique is also readily applicable to the measurement of the stress-strain response of any micro-scale specimen, such as other metals, polymers, etc. Also, the measured displacement field by obtained by DIC can be used as the base for calculating the strain field on the surface of a specimen.
158

Surface studies of poly(hydroxybutyrate-co-hydroxyvalerate)

Naismith, Judith January 2001 (has links)
No description available.
159

The design and implementation of a flexible manufacturing system for a surface mounting production line

Chodos, Mark, Steven January 1990 (has links)
A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Engineering. / The viability of introducing a Surface Mount production line is chiefly determined by the reliability characteristics of the components being used. Surface Mount Technology (SMT) is entirely new and although related to traditional through-hole processes, requires different components, assembly techniques and design methods. The purpose of the literature survey is primarily to determine whether surface mount components meet today's industrial requirements with respect to their manufacturing reliability and availability. A brief review of the evolution of SMT is also presented. This study finds that the implementation of SMT should be given highest priority by manufacturing companies in order to maintain their share of the marketplace. Surface Mount Technology embodies a totally new automated circuit assembly process, using a new generation of electronic comporents: surface mounted devices (SMDs). Smaller than conventional components, SMDs are placed onto the surface of the substrate. From this, the fundamental difference between SMD assembly and convencional through-hole component assembly arises; SMD component positioning is relative, not absolute. When a through-hole component is inserted into a pcb, either the leads go through the hales or they don't. An SMD, however, is placed onto the substrate surface, it's position only relative to the solder lands, and placement accuracy is therefore influenced by variations in the substrate track pattern, component size, and placement machine accuracy. Other factors influence the layout of SMD substrates. For example, will the board be a mixed-print ( a combination of through-hole components and SMDs) or an all-SMD design? Will SMDs be placed on one side of the substrate or both? And there are process considerations like what type of machine will place the components and how will they be soldered? This project describes in detail the processes involved in setting up an SMT facility. A simulation program was developed to verify the viability of these processes. The simulation program was also applied to an existing SMT facility and together with developed optimization software, attempted to identify and resolve some of the major problems. All this was achieved, and the extent to which simulation could be used as an efficient production tool, was highlighted. / AC2017
160

A survey of the cylinder machine boxboard industry

Rohde, Charles N. January 1965 (has links)
Thesis (M.B.A.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2031-01-01

Page generated in 0.0375 seconds