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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.
241

Estimating patients' energy requirements: Cancer as a case study.

Reeves, Marina Michelle January 2004 (has links)
The nutritional care and management of patients includes provision of adequate nutrition support to ensure that they attain and maintain a desirable body weight, improve nutritional status and avoid negative outcomes associated with over- or underfeeding. The success of nutrition support relies on accurately estimating energy requirements so that adequate energy and nutrients can be provided to the patient. Energy requirements are most accurately determined by measurement of energy expenditure. Most methods for doing so however are expensive, time-consuming, require trained technicians to perform them and are therefore impractical in the clinical setting. As such, prediction equations, which are easy to use, inexpensive and universally available, are commonly used to estimate the energy requirements of hospitalised patients. The accuracy of these equations however is questionable. Recently, a new portable hand-held indirect calorimeter (MedGem(tm), HealtheTech, USA), which has been promoted for its ease of use and relatively short measurement time, has been validated in healthy subjects but is yet to be validated in patients with illnesses. Weight loss and malnutrition occur commonly in patients with cancer and are often thought to be associated with disturbances in energy metabolism caused by the tumour. Minimising weight loss is an important goal for the nutritional care of patients with cancer. The ability to accurately determine the energy requirements of these patients is therefore essential for the provision of optimal nutrition support. This research project proceeded in two phases. Phase 1 aimed to determine current methods used by dietitians for estimating adult patients' energy requirements using a descriptive study. Results of this study informed phase 2, which aimed to investigate differences in energy expenditure of cancer patients compared to healthy control subjects and to compare different methods for determining energy requirements of people with cancer in the clinical setting. To address phase 1 a national cross-sectional survey of dietitians working in acute care adult hospitals was undertaken to determine their usual dietetic practice with respect to estimating patients' energy requirements. Responses to the survey (n=307, 66.2%) indicated a large variation in dietitians' practice for estimating energy requirements particularly with respect to the application of methods involving injury factors. When applied to a case study, these inconsistencies resulted in an extremely wide range for the calculated energy requirement, suggesting that there is error inherent in the use of prediction methods, which may be associated with negative consequences associated with under- or overfeeding. The types of patients for whom dietitians estimate energy requirements appears to be heavily influenced by feeding method. Initial dietetic education was identified as the main influencing factor in the choice of method for estimation of energy requirements. Phase 2 was addressed using four studies based on the same study population - a case-control study, two clinical validation studies and a measurement methods study. Patients had histologically proven solid tumours, excluding tumours of the breast, prostate and brain, and were undergoing anti-cancer therapy (n=18). Healthy control subjects were group matched to cancer patients by gender, age, height and weight from a purposive sample (n=17). Resting energy expenditure (REE) was measured by respiratory gas exchange using a traditional indirect calorimeter (VMax 229) and the MedGem indirect calorimeter. A measurement methods side-study established that steady state defined as a three-minute period compared to a five-minute period measured REE within clinically acceptable limits. REE was also predicted from a range of prediction equations. Analyses of available data found that REE in cancer patients was not significantly different from healthy subjects, with only a 10% higher REE observed in this sample of cancer patients when adjusted for fat free mass. For both cancer patients and healthy subjects the portable MedGem indirect calorimeter and all prediction equations did not measure or estimate individual REE within clinically acceptable limits compared to the VMax 229 (limits of agreement of approximately -40% to 30% for both the MedGem and prediction equations). Collectively, the results of this research project have indicated that current practical methods for determining patients' energy requirements in a clinical setting do not accurately predict the resting energy expenditure of individual subjects, healthy or with cancer. Greater emphasis should therefore be placed on ensuring intake meets requirements. For this to occur, dietetic practice should be focused on directly monitoring both patients' actual energy intake and patient outcomes, such as weight, body composition and nutritional status, to determine whether energy requirements are being met. This research has led to multiple recommendations for dietetic practice, focusing on the standardisation of education practices. Recommendations for future research address methodological improvements.
242

Thermal Properties of Starch From New Corn Lines as Impacted by Environment and During Line Development

Elizabeth M. Lenihan January 2003 (has links)
Thesis (M.S.); Submitted to Iowa State Univ., Ames, IA (US); 12 Dec 2003. / Published through the Information Bridge: DOE Scientific and Technical Information. "IS-T 2547" Elizabeth M. Lenihan. 12/12/2003. Report is also available in paper and microfiche from NTIS.
243

The influence of chemical composition and heat treatment on microstructure and mechanical/tribological properties of cobalt-based Tribaloy alloys /

Xu, Wei. January 1900 (has links)
Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 57-63). Also available in electronic format on the Internet.
244

A method of ultimate analysis of organic substances developed from combustion in a bomb calorimeter ...

Merkus, Peter Johannes, White, Alfred H. January 1900 (has links)
Extracts from Thesis (Ph. D.)--University of Michigan, 1934. / Part 2 has title: Evaluation of oils from the manufacture of carburetted water gas by their available hydrogen content. Bibliography at end of each part.
245

Spectroscopic and calorimetric studies of aggregated macromolecules

Kitts, Catherine Carter, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
246

Thermoanalytische und infrarotspektroskopische Untersuchungen am System Polyvinylalkohol, Borsäure

Smolinski, Ralf. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2003--Dortmund.
247

The influence of adhesive curing temperature upon the performance of FRP strengthened steel structures at ambient and elevated temperatures

Othman, Daryan Jalal January 2017 (has links)
The structural adhesives widely used in structural strengthening applications are thermoset ambient cure adhesive polymers. At ambient temperatures, these polymers are in a relatively hard and inflexible state. At higher temperatures, the material becomes soft and flexible. The region where the molecular mobility changes dramatically is known as the glass transition temperature Tg and often is presented as a single value. Epoxy polymers exhibit a significant reduction in mechanical properties near glass transition temperature Tg when they are exposed to elevated temperatures. Glass transition temperature Tg is used to characterise the change in epoxy adhesive properties with changing temperature. The mechanical properties of epoxies tend to improve with curing temperature. This is because the crosslink density between the adhesive molecular structures increases during the curing process consequently the Tg improves. The aims of this work are first to demonstrate the importance of curing temperature. Second, to investigate the influence of glass transition temperature !! improvement on the performance of EB-FRP strengthened steel structures in flexure at ambient and elevated temperatures. Third, to compare analytical results with experimental results from the flexure tests results. Finally, to compare the current design guideline recommendations with the flexure tests results. The most commonly used methods to evaluate Tg Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC) were used to study Tg. Two off-shelf structural adhesives were investigated to understand their property variation with temperature. Epoxy coupons were cured at different elevated temperature and humidity environments up to 28 days. A combination of two extreme relative humidity of 0 and 100% and variable curing temperatures between 15 to 80°C were considered. From a test matrix of 300 DMA and over 250 DSC coupons these conclusions were drawn. First, ambient cured thermosets have a linear relationship between Tg and curing temperature, but Tg is reduced if a certain temperature is reached. Second, a fully cured adhesive requires heating treatment. Without a curing regime, designed Tg may never be achieved. Finally, curing time is crucial at the low curing temperatures while it is less significant at the higher curing temperature. The results of Tg investigation were used to select appropriate curing temperature that the adhesives resistance to temperature can be maximised without damaging the mechanical properties. The study helps designs to understand and assess the behaviour of these two adhesives when they are exposed to extreme temperatures. The study increases the awareness that a fully cured adhesive may never be achieved at ambient or low temperatures. It is important to find the mechanical properties and Tg when the coupons are exposed to the same curing temperature. To investigate the influence of glass transition temperature Tg improvement on the performance of EB-FRP strengthened steel structures in flexure at ambient and elevated temperature, nine three metre length beams were designed to behave as a concrete-steel composite bridge deck. The beams were tested in four-point bending. Lap shear, DMA test, and pull-off adhesion samples were prepared and cured at the same conditions and tested at ambient temperature. Six beams were tested under only mechanically loading at ambient temperature, including the control specimen. Five beams were tested at ambient temperature to show the effects of adhesive curing on FRP strengthened sections. A significant increase of load capacity of the adhesive joints was achieved due to the curing of the joints at elevated temperature. The failure occurred was in the same manner. An increase in the load capacity was observed with increasing curing temperature. An increase of approximately 25% was noticed in the ultimate load capacity of the specimens cured at 50°C compared to the specimens cured at 30°C. The load capacity of lap-shear specimens cured at 50°C was 28% higher than the specimens cured at 30°C. Three specimens were tested under mechanical and thermal loading. A bespoke thermal chamber was designed and fabricated to apply a controlled thermal loading. The beams were loaded mechanically up to 350kN, first. The temperature of the specimens was then increased at a rate of 0.8°C/min. The sustained load 350kN remained constant during the heating phase. Digital Image Correlation (DIC) technique was used to detect the slippage of the tip of the FRP plates. The only specimen cured at 30°C showed relatively poor performance compared to the two specimens cured at 50°C. The plate ends started to slip when the adhesive storage modulus from the DMA runs reduced approximately by 15 and 18% for the beams cured at 30 and 50°C respectively. Pull-off adhesion tests confirmed that adequate surface preparation of over 25 MPa was achieved The flexural model for the composite steel section represented to predicate load-deflection behaviour of the specimens using semi-experimental constitutive material law. The model successfully predicts the load-deflection behaviour of specimens, considering the strain hardening contribution. A bond stress analysis is also presented, which counts for the effect of FRP plate moment effect. The experimental and theoretical FRP plate slippage assuming only adhesive degradation with temperature are compared. The analytical bond models cannot predict the experimental failure because the linear elastic material properties were assumed and the failure was adhesion.
248

Characterization of Nylon-12 in a Novel Additive Manufacturing Technology, and the Rheological and Spectroscopic Analysis of PEG-Starch Matrix Interactions

Craft, Garrett Michael 05 April 2018 (has links)
In this work differential scanning calorimetry, dynamic mechanical analysis, Fourier-Transformed Infrared Spectroscopy [FT-IR] and polarized light microscopy will be employed to characterize polymeric systems. The first chapter broadly covers polymer synthesis and important characterization methods. In the second chapter, a polyamide (PA12) will be sintered via a novel additive manufacturing (AM) technology developed here at USF termed LAPS (Large Area Projection Sintering). LAPS uses extended sintering timespans to ensure complete melting and densification of the polymer powder over the entire two-dimensional area of the part’s footprint. Further, it allows for the printed layer to crystallize and shrink in its entirety as the temperature falls below the crystallization temperature prior to the next layer being added. The printed parts (termed coupons) will be assayed by DSC and polarized light microscopy to determine sintering efficacy. Additionally, the parts will be compared to coupons printed with conventional methods to show that the USF AM technology shows superior elongation at break (EaB), with comparable ultimate tensile strength (UTS) and Young’s Modulus to laser sintered coupons. This is notable as conventional AM methods produce parts which usually compromise between EaB and modulus. The EaB of LAPS-printed parts is comparable to injection molding (IM) grade PA12, which is remarkable as IM grade PA12 powder normally has higher molecular weight and limited crystallinity. The reduced crystallinity of IM grade PA12 parts is thought to be due to the high shear rates during injection and fast cooling rates post-fabrication. Further, the USF LAPS parts show minimal or no detectable porosity. Porosity is an artifact of the sintering process which conventional techniques like laser sintering (LS) have little ability to mitigate, as higher energy wattages simply burn and degrade the polymer surface with insufficient time available for heat transfer and bulk melt flow. Porosity is documented as one of the leading causes of part failure and decreased mechanical properties in the literature, and as such the USF AM technology is in the process of being patented as of March, 2018. Chapters three through six will explore a phenomenon first noticed by clinicians at the James A. Haley Veterans Hospital. They observed that starch-thickened drinks for patients suffering from dysphagia became dangerously thinned down upon addition of the osmotic drug polyethylene glycol (PEG) 3350, marketed as Miralax®. Starch-based hydrocolloids are common thickeners used for patients with dysphagia, and so any incompatibility with such a ubiquitous drug as PEG 3350 poses an immediate danger. Patients with the disorder can suffer increased rates of aspiration-related pneumonia, incurring up to nearly a 60% fatality rate within a year. Chances for aspiration greatly increase for food items which are too inviscid to safely swallow. Rheology and FT-IR spectroscopy will be used to show that the breakdown of the starch network in aqueous solution is dependent upon the molecular weight of PEG. As the molecular weight of PEG is reduced to that of a small molecule (~300MW) from its large drug form (3350MW), the structure stabilizes and can resist shearing forces in a steady shear rheological experiment. Spectroscopy will show that PEG molecular weight also influences syneresis and the crystallinity of the starch hydrocolloid solutions. It is postulated that the molecular weight of PEG influences its miscibility in starch solutions, and its ability to interrupt the hydrogen bonding and entanglements which maintain the elastic framework which allow starch thickeners to impart viscosity and resist shearing forces. When this framework collapses, absorbed water is expelled as evidenced as a biphasic separation where water collects on top of the starch suspension. This was the phenomenon observed by the clinicians at the Veterans’ Hospital.
249

Calorimetria indireta em crianças e adolescentes com bronquiolite obliterante pós-infecciosa

Paludo, Juliana January 2010 (has links)
Objetivos: Quantificar o gasto energético de crianças e adolescentes com bronquiolite obliterante pós-infecciosa acompanhados em ambulatório de pneumologia pediátrica e comparar com crianças e adolescentes hígidos. Metodologia: Estudo transversal com grupo controle incluindo 72 crianças e adolescentes de 8 a 18 anos. Comparou-se dois grupos de 36 indivíduos, um com diagnóstico de BO e outro hígido, os quais foram pareados pelo gênero, idade e classificação do IMC. Para avaliação nutricional utilizou-se a antropometria e a composição corporal. O gasto energético foi medido pela calorimetria indireta; o fator atividade pelo recordatório 24h de atividades físicas e a ingestão energética pelos inquéritos alimentares. Resultados: Os resultados a seguir são apresentados, respectivamente, para o grupo BO e para o grupo controle: idade (11,8 ± 2,7) e (12,3 ± 2,8); índice de massa corporal (18,9 ± 4,0 Kg/m2) e (18,8 ± 3,4 Kg/m2); gasto energético de repouso (GER) (1717,6 ± 781,5) e (2019,9 ± 819); gasto energético total (GET) (2677,5 ± 1514,0 Kcal/dia) e (3396,1 ± 1557,9Kcal/dia); estimativa da ingestão energética (2294,1 ± 746,7Kcal/dia) e (2116,5 ± 612,1Kcal/dia). O GER e GET não foram estatisticamente diferentes entre os grupos (p= 0,102; p=0,051). O GER não foi estatisticamente diferente nem quando ajustado para massa magra (p=0,116). O GER está associado a MM (r=0,490; p0,001), sendo que quanto maior a MM, maior o gasto energético. Não houve diferenças estatisticamente significativas entre o GET e o consumo energético no grupo BO (p=0,202). O grupo controle consumiu, em média, 1.279,6Kcal a menos do que o previsto pelo GET (p<0,001). Houve diferença estatisticamente significante entre o gasto energético medido pela calorimetria indireta e o estimado pelas fórmulas de predição. Todas as fórmulas de predição subestimaram a necessidade energética. Conclusão: O GER e o GET foram semelhantes entre os grupos. A estimativa da ingestão energética das crianças e adolescentes hígidos foi menor que o GET. Os resultados sugerem que todas as fórmulas de predição utilizadas subestimaram as necessidades energéticas quando comparadas com a calorimetria indireta. / Objectives: To quantify energy expenditure in children and adolescents with post-infectious obliterans bronchiolitis (OB) receiving outpatient pediatric pulmonology care and compare them with healthy children and adolescents. Methods: Cross-sectional study with control group including 72 children and adolescents aged 8-18 years. Two groups of 36 individuals were compared – one diagnosed with OB and another healthy – which were paired as to gender, age, and body mass index classification. Anthropometry and body composition were used for nutritional assessment. Energy expenditure was measured by indirect calorimetry, activity factor was assessed through 24-hour recall, and energy intake was measured by nutrition surveys. Results: The following results are respectively presented to the OB group and to the control group: age (11.8 ± 2.7) and (12.3 ± 2.8); body mass index (18.9 ± 4.0 Kg/m2) and (18.8 ± 3.4 Kg/m2); resting energy expenditure (REE) (1717.6 ± 781.5) and (2019.9 ± 819); total energy expenditure (TEE) (2677.5 ± 1514.0 Kcal/day) and (3396.1 ± 1557.9 Kcal/day); energy intake estimate (2294.1 ± 746.7 Kcal/day) and (2116.5 ± 612.1 Kcal/day). REE and TEE were not statistically different between groups (p=0.102; p=0.051). REE was not statistically different even when adjusted for lean mass (p=0.116). REE is associated with lean mass (r=0.490; p<0.001) – the higher the lean mass, the higher the energy expenditure. There were no statistically significant differences between TEE and energy expenditure in the OB group (p=0.202). The control group had an average intake 1279.6 Kcal lower than that predicted by TEE (p<0.001). There was a statistically significant difference between energy expenditure measured by indirect calorimetry and that estimated by prediction equations. All prediction equations underestimated energy needs. Conclusion: REE and TEE weresimilar between groups. Energy intake estimate in the healthy children and adolescents was lower than TEE. Results suggest that all prediction equations used in this study underestimated the energy needs when compared with indirect calorimetry.
250

Evolução de crianças e adolescentes com excesso de peso após manejo com dieta ajustada por calorimetria indireta

Koglin, Gabriela January 2012 (has links)
Introdução: As mudanças ocorridas no estilo de vida nas últimas décadas têm levado a um aumento na prevalência de excesso de peso. Isso afeta tanto países desenvolvidos como aqueles em desenvolvimento e também todas as faixas etárias. Diversas intervenções para reverter essa situação vêm sendo testadas, porém, em crianças e adolescentes o melhor manejo para reverter esse quadro ainda não está completamente elucidado. Objetivo: Avaliar as mudanças ocorridas no escore-z do índice de massa corporal (zIMC), circunferência do braço (CB), prega cutânea tricipital (PCT) e subescapular (PCSE), circunferência muscular do braço (CMB), percentual de gordura corporal (GC), circunferência da cintura (CC) e exames bioquímicos em crianças e adolescentes após uma intervenção exclusivamente dietoterápica ajustada pela taxa metabólica basal (TMB) obtida através do exame de calorimetria indireta (CI). Procedimentos Metodológicos: Após randomização, os participantes alocados para essa pesquisa participaram de encontros mensais individuais com a nutricionista responsável pelo projeto, pelo período de 1 ano. Os participantes tinham entre 8 e 15 anos, todos com excesso de peso (zIMC≥+1). As medidas antropométricas e de GC foram avaliadas na inclusão, no 6° e no 12° mês, após cada criança ou adolescente ser submetido ao exame de CI. A GC foi medida através do equipamento de bioimpedância elétrica. A coleta de sangue para as análises bioquímicas foi realizada após a CI. Cada participante recebeu uma dieta ajustada pelo valor do exame de CI. Usamos ANOVA para medidas repetidas, e teste de Friedman e Cochran’s Q para avaliar os resultados. Para as análises estatísticas foi utilizado o PASW 18.0 para Windows e valores-P<0,05 foram considerados estatisticamente significativos. Resultados: Completaram as três avaliações 27 participantes, com média de idade de 12±2 anos, 51,9% do sexo feminino. A TMB não apresentou mudança significativa ao final do estudo (P=0,233), enquanto o zIMC reduziu -0,19±0,04 nos primeiros 6 meses e -0,17±0,05 (P=0,014) ao final do seguimento. A CB aumentou em 12 meses e a PCSE nos últimos 6 meses, permanecendo estável ao final da pesquisa. O percentual de GC reduziu inicialmente, mas nos últimos 6 meses apresentou aumento, ainda que mais da metade dos participantes tenha reduzido a GC em 12 meses. O colesterol total (CT) e a lipoproteína de baixa densidade (LDL-c) reduziram nos primeiros 6 meses (-11,5±2,7;P=0,001/-8,1±2,5;P=0,011), mas essa redução não se manteve significativa ao final da intervenção. A maior parte das crianças e adolescentes reduziu os valores de triglicerídeos, LDL-c (88,9%) e CT (66,7%) ao final do estudo. Conclusões: O manejo dietoterápico da obesidade infanto-juvenil realizado por um nutricionista, com encontros mensais, é efetivo após 12 meses de intervenção e, especialmente em 6 meses. / Background: The changes in lifestyle over the past decades have led to an increase in the prevalence of overweight. This affects both developed countries and developing ones as well as all age groups. Several interventions to reverse this situation have been tested, however, in children and adolescents the best management to reverse this situation is not yet fully elucidated. Objective: To evaluate the changes in the z-score of body mass index (zBMI), arm circumference (AC), triceps skinfold (TSF) and subscapular (SSF), arm muscle circumference (AMC), body fat percentage (BF), waist circumference (WC) and biochemical tests in children and adolescents after an intervention only dietotherapeutic adjusted for basal metabolic rate (BMR) was obtained through examination of indirect calorimetry (IC). Methodological Procedures: After randomization, participants allocated to this research participated in monthly and individual meetings with the nutritionist responsible for the project for a period of one year. Participants aged between 8 and 15 years, all overweight (≥ zBMI+1). Anthropometric measurements and BF were evaluated at inclusion in the 6th and 12th month after each child or adolescent be submitted to the examination of IC. The BF was measured by bioelectrical impedance equipment. Blood samples for biochemical analysis was performed after IC. Each participant received a diet adjusted by the value of IC exam. We used repeated measures ANOVA and Friedman and Cochran's Q test to evaluate the results. The statistical analysis was used PASW 18.0 for Windows and P-values <0.05 were considered statistically significant. Results: Completed all three assessments 27 participants, mean age 12±2 years, 51.9% were female. The BMR showed no significant change at the end of the study (P=0.233), while the Zimc reduced -0.19 0.04 in the first 6 months and -0.17±0.05 (P=0.014) at the end of follow-up. The AC increased by 12 months and SSF in the last six months, remaining stable at the end of the study. The BF percentage was initially reduced, but in the last six months had increased, although more than half of the participants has reduced BF in 12 months. The total cholesterol (TC) and low density lipoprotein (LDL-c) reduced in the first 6 months (-11.5±2.7;P=0.001/-8.1±2.5;P=0.011), but this significant reduction was not maintained to the end of the intervention. Most children and adolescents reduced the values of triglycerides, LDL-c (88.9%) and TC (66.7%) at the end of the study. Conclusions: The dietary management of obesity in children and adolescents conducted by a nutritionist, with monthly meetings, is effective after 12 months of intervention, and especially in six months.

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