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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.
91

Pathogenesis of post surgical adhesions and prevention using a novel fibrin sealant

Ricketts, Sally-Ann January 1999 (has links)
Post surgical adhesions (PSAs) are an inevitable outcome of surgery and their presence leads to pathogeneses and significant economic impact. The studies within this thesis utilised standard and reproducible abrasion models, in rabbits, pigs and rats, to investigate the formation and maturation of PSAs with strict quantitative analyses. These studies have shown that the development of PSAs is a series of complex, multi-factorial processes. PSA development can be classified into two stages: (i) PSA modelling occurring up to/including 16 hours post injury characterised by the inflammatory response and fibrin deposition and maturation; and (ii) PSA remodelling occurring from 16 hours onwards and characterised by tissue repair, collagen deposition and maturation and chemical mediation by TGF-P. Treatment with VivostatTM System Derived (novel) Fibrin Sealant significantly reduced the formation of PSAs with mean PSA reduction of 80% for the rabbit uterine horn abrasion model, from 3 separate studies; 83% for the pig stomach/colon/caecum abrasion model, from 2 separate studies; 80% for the rat caecum abrasion model. This is significantly better than other fibrin sealants investigated in this thesis. PSA prevention with novel fibrin sealant demonstrated a similar pattern to PSA development, with two stages of development evident: (i) tissue generation modelling occurring up to/including 16 hours post injury characterised by the inflammatory response and fibrin deposition and maturation; and (ii) tissue generation remodelling occurring from 16 hours onwards and characterised by tissue repair, collagen deposition and maturation and chemical mediation by TGF-P. However the extent and subsequent time taken for these changes to occur was significantly reduced. The prevention of PSAs and alterations of wound healing by novel fibrin sealant is most probably due to the sealant acting as a haemostat, as well as a physical barrier. Thus preventing fibrinous and subsequent fibrous PSA formation.
92

Design and simulation of pressure swing adsorption cycles for CO2 capture

Oreggioni, Gabriel David January 2015 (has links)
Carbon capture and storage technologies (CCS) are expected to play a key role in the future energy matrix. Different gas separation processes are under investigation with the purpose of becoming a more economical alternative than solvent based post combustion configurations. Previous works have proved that pressure swing adsorption (PSA) cycles manage to reach similar carbon capture targets than conventional amine process but with approx. a 50% lower specific energy consumption when they are applied at lab scale. These encouraging results suggest that research must be undertaken to study the feasibility of this technology at a low to medium power plant scale. The simulation of PSA cycles is a computationally challenging and time consuming task that requires as well a large set of experimentally measured data as input parameters. The assumption of Equilibrium Theory reduces the amount of empirically determined input variables that are necessary for modelling adsorption dynamics as well as enabling a simpler code implementation for the simulators. As part of this work, an Equilibrium Theory PSA cycle solver (Esim) was developed, the novel tool enables the quantification of the thermodynamic limit for a given PSA cycle allowing as well a pre-selection of promising operating conditions and configurations (high separation efficiency) for further investigation by using full governing equation based software The tool presented in this thesis is able to simulate multi-transition adsorption systems that obey any kind of equilibrium isotherm function without modifying its main code. The second part of this work is devoted to the design, simulation and optimisation of two stage two bed Skarmstrom PSA cycles to be applied as a pre-combustion process in a biomass gasification CHP plant. Simulations were carried out employing an in house software (CySim) in which full governing equations have been implemented. An accurate analysis of the operating conditions and cycle configurations was undertaken in order to improve the performance of the carbon capture unit. It was estimated that the energy penalty associated with the incorporation of the adsorptive pre combustion process was lower for a conventional post combustion solvent unit, leading as well to lower specific energy consumption per unit of captured CO2 and higher overall efficiencies for the CHP plant with installed pre-combustion PSA cycles. This work is pioneer in its kind as far as modelling, simulation, optimisation and integration of PSA units in energy industries is concerned and its results are expected to contribute to the deployment of this technology in the future energy matrix.
93

Prediction of survival in prostate cancer : aspects on localised, locally advanced and metastatic disease

Robinson, David January 2008 (has links)
Background and aims: The clinical course of prostate cancer is highly variable and difficult to predict.Stage at presentation, grade and PSA at diagnosis are traditionally used to predict outcome. The aimof this thesis was to identify strategies for improved survival prediction in men with prostate cancer.The way in which prostate cancer affects a population based‐cohort and how routinely measuredvariables can be used to predict survival in an intermediate to long follow‐up period were explored.From this large cohort we separately evaluated how survival can be predicted in men with incidentalcarcinoma (T1a and b) and locally advanced disease (lymph node‐ positive). Immunohistochemistrywas added to routinely measured variables in the subgroup of men with incidental carcinoma.Furthermore, we assessed how the outcome of metastatic disease may be predicted from informationavailable at diagnosis, and during the first six months after treatment. Finally we predicted survivalfor men with metastatic hormone‐refractory prostate cancer (HRPC). Material and methods: From the Swedish South‐East Region Prostate Cancer Register data on 8887men were studied and the impact of tumour grade, serum PSA concentration, TNM classification andtreatment was studied in relation to survival.Furthermore, an evaluation of the disease‐specific mortality of conservatively managed incidentalcarcinoma in relation to T‐category, Gleason score, p53, Ki‐67, Chromogranin A and serotonin wasmade. From the same register we studied whether common predictive factors such as serum‐PSA, Tcategoryand biopsy tumour grade could be used to better assess the prognosis of men with nodepositiveprostate cancer. Using data from the clinical trial SPCG‐5 we studied the possibility of serialmeasurements of PSA and ALP being to predict survival early in the course of hormone‐treatedmetastatic prostate cancer. From the same trial, we also assessed the value of PSA kinetics inpredicting survival and related this to baseline variables in men with metastatic HRPC. Results: In the South–East Region, where screening was seldom done the median age at diagnosisand death was 75 and 80 years respectively, and 12% were diagnosed before the age of 65 years. Hightumour grade, high serum PSA and high T category were associated with poor outcome. The projected 15‐year disease‐specific survival rate was 44% for the whole population. In total, 18% ofpatients had metastases at diagnosis and their median survival was 2.5 years. In the cohort of men with incidental carcinoma, 17% died of prostate cancer. Of 86 patients withGleason score ≤5, three died of prostate cancer. Independent predictors of disease‐specific mortality inmultivariate analysis were category T1b prostate cancer, Gleason score >5 and high immunoreactivityof Ki‐67. Men with lymph‐node positive disease have a median cancer‐specific survival of 8 years.Preoperatively known factors such as PSA, T‐category, age, mode of treatment, failed to predictoutcome, but there was a weak, not statistically significant difference in cancer‐specific survival inrelation to tumour grade. Initial ALP, and ALP and PSA after 6 months of treatment were the serum markers that provided thebest prognostic information about the long‐term outcome of metastatic prostate cancer. In men withHRPC, PSA velocity alone gave a better prediction of survival than all other PSA kinetic variables. Conclusion: In an almost unscreened population, prostate cancer is the elderly mans disease but themortality is high. Ki‐67 may be of value in addition to stage and Gleason score for predicting theprognosis in men with incidental carcinoma.The impact of lymph node metastases on survival overrides all other commonly used prognosticfactors. By following ALP and PSA for 6 months it is possible to predict outcome in metastatic prostate cancer.This gives a much better prediction than baseline PSA and helps to select men with a poor prognosis.By combining PSAV with the variables available at baseline, a better ground for treatment decisionmakingin men with HRPC is achieved.
94

Cellulose Nanocrystals: Renewable Property Modifiers for Pressure Sensitive Adhesives

Dastjerdi, Zahra January 2017 (has links)
Pressure sensitive adhesives (PSAs) are polymeric materials with versatile applications in industrial and consumer products such as protective films, product labels, masking tape, and sticky notes, to name a few applications. World demand for emulsion–based products is on the rise due to worldwide legislation on solvent emissions. In order to completely replace emulsion-based PSAs with their solvent-based counterpart, the property modification of emulsion-based PSAs is required. The use of nanomaterials to modify polymer properties is well established. The aim of this thesis was to use cellulose nanocrystals (CNCs) as property modifiers for emulsion-based PSAs. CNCs are recognized as a highly efficient reinforcement nanofiller. Owing to their environmentally friendly characteristics, low density, high aspect ratio, non-toxicity, and abundant availability, the application of CNCs in composite materials is gaining increasing attention. In this thesis, the inclusion of CNCs in emulsion-based PSAs was carried out through in situ emulsion polymerization and blending technique. To the best of our knowledge, there is limited information about the synthesis of CNC/PSAs nanocomposites via in situ emulsion polymerization and the evaluation of their mechanical performance. The addition of CNCs to the polymerization formulation caused latex instability due to the negatively charged surfaces of the CNCs. After numerous attempts to overcome the stability issues, a stable polymerization formulation and protocol were developed. CNC/PSAs were synthesized via in situ seeded-semi batch emulsion polymerization, which is a common commercial production pathway for PSAs. The mechanical performance of the resulting PSA nanocomposite films, namely, shear strength, tack, and peel strength, was evaluated at several CNC loadings. All three PSA adhesive properties were simultaneously enhanced with increasing CNC loading. The inclusion of CNCs into the films increased their hydrophilicity. Consequently, the PSA films’ improved wettability on a stainless steel substrate imparted greater tack and peel strength. The blending of the CNCs with a base latex also led to improved adhesive properties. However, the property modification through blending was not as effective as that for the CNC/PSA films synthesized via in situ emulsion polymerization. Thus, CNCs are safe nanomaterials that have been shown to provide remarkable property enhancement of emulsion-based PSA films at low loadings (1wt%).
95

Strategie francouzských výrobců automobilů na mezinárodních trzích / Strategies of French Car Manufacturers on International Markets

Snížek, Martin January 2012 (has links)
This diploma thesis aims at comparing strategies of French car manufacturers Renault and PSA Peugeot Citroën on international markets. The first chapter is focused on unveiling the particularities of different markets with paying special attention to distinguishing traditional automotive centres from emerging economies. The second part of the thesis presents Renault and its activities on international markets. Renault's activities are more profoundly studied through analysis of production (geographic distribution and its evolution, methods of entering new markets) and sales. The same structure is applied to the third chapter concerning PSA Peugeot Citroën. The author comes to a conclusion that even though France and Europe remain the main markets for both car makers their importance declines to the benefit of developing countries. Moreover, it was found out that both car manufacturers are entering new markets via cooperation with other car makers.
96

Site Specifc Growth of Metal Catalyzed Silica Nanowires for Biological and Chemical Sensing

Huey, Eric G. 31 July 2013 (has links)
In this research the integration of nanostructures and micro-scale devices was investigated using silica nanowires to develop a simple yet robust nanomanufacturing technique for improving the detection parameters of chemical and biological sensors. This has been achieved with the use of a dielectric barrier layer, to restrict nanowire growth to site-specific locations which has removed the need for post growth processing, by making it possible to place nanostructures on pre-pattern substrates. Nanowires were synthesized using the Vapor-Liquid-Solid growth method. Process parameters (temperature and time) and manufacturing aspects (structural integrity and biocompatibility) were investigated. Silica nanowires were observed experimentally to determine how their physical and chemical properties could be tuned for integration into existing sensing structures. Growth kinetic experiments performed using gold and palladium catalysts at 1050 ˚C for 60 minutes in an open-tube furnace yielded dense and consistent silica nanowire growth. This consistent growth led to the development of growth model fitting, through use of the Maximum Likelihood Estimation (MLE) and Bayesian hierarchical modeling. Transmission electron microscopy studies revealed the nanowires to be amorphous and X-ray diffraction confirmed the composition to be SiO2 . Silica nanowires were monitored in epithelial breast cancer media using Impedance spectroscopy, to test biocompatibility, due to potential in vivo use as a diagnostic aid. It was found that palladium catalyzed silica nanowires were toxic to breast cancer cells, however, nanowires were inert at 1µg/mL concentrations. Additionally a method for direct nanowire integration was developed that allowed for silica nanowires to be grown directly into interdigitated sensing structures. This technique eliminates the need for physical nanowire transfer thus preserving nanowire structure and performance integrity and further reduces fabrication cost. Successful nanowire integration was physically verified using Scanning electron microscopy and confirmed electrically using Electrochemical Impedance Spectroscopy of immobilized Prostate Specific Antigens (PSA). The experiments performed above serve as a guideline to addressing the metallurgic challenges in nanoscale integration of materials with varying composition and to understanding the effects of nanomaterials on biological structures that come in contact with the human body.
97

Relação antígeno prostático específico com hiperplasia prostática benigna e adenocarcinoma prostático em casos de Pernambuco

Hermínia Cavalcanti França Ferraz, Graças January 2004 (has links)
Made available in DSpace on 2014-06-12T23:03:57Z (GMT). No. of bitstreams: 2 arquivo8832_1.pdf: 827062 bytes, checksum: 9b09883078373037c2ce35a48c27f043 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2004 / O câncer de próstata é um dos cânceres de maior incidência no sexo masculino e tendo em vista a escassez de pesquisas com a população em Pernambuco, se faz necessário estudar a relação do PSA com a idade nos casos de hiperplasia prostática benigna (HPB) e adenocarcinoma prostático, bem como nestes a relação do antígeno prostático específico (PSA) com o escore de Gleason. Estudamos 55 casos de resultados histopatológicos (entre 1996 e 2002) do arquivo do Centro Integrado de Anatomia Patológica Hospital Universitário Osvaldo Cruz, sendo 37 de HPB (média de idade 70,4 anos) e 18 de adenocarcinoma prostático (média de 73,2 anos). Os casos de HPB foram divididos em grupos pelos níveis de PSA total, sendo 37 em P1 (0 = PSAt = 113 ng/mL), 7 em P2 (PSAt = 4ng/mL), 15 em P3 ( 4,1 = PSAt = 10,0 ng/mL), 15 em P4 (PSAt = 10,1 ng/mL), 7 em P5 (PSAt = 4,1 ng/mL) e 30 em P6 (PSAt > 4,1 ng/mL); de acordo com a idade em grupos: 37 em I1 (de 55 a 89 anos), 9 em I2 (= 65 anos) e 28 em I3 (= 65 anos). Os casos de adenocarcinoma prostático foram divididos em grupos de acordo com o PSA total, sendo 18 em P1, 12 em P2, e 6 em P3; de acordo com a idade em grupos: 18 em I1, 4 em I2 e 14 em I3; de acordo com o escore de Gleason em grupos: 18 em G1 (2 a 10), 12 em G2 (2 a 6) e 6 em G3 (7 a 10). Para a análise estatística foram utilizados o teste Quiquadrado, o teste exato de Fisher, o teste de Spearman e Pearson. Valores de p<0,05 foram considerados estatisticamente significantes. Nos casos de HPB não houve diferença entre proporções: Idade (grupos I2 e I3) versus PSA (grupos P2, P3, P4) (p=0,550), Idade (grupos I2 e I3) versus PSA (grupos P5 e P6) (p=0,656), isto pode ser devido a idade mínima em nossos casos ser de 55 anos; houve correlação significativa entre: Idade (grupo I1) versus PSA (grupo P1) (p=0,027). Nos casos de adenocarcinoma prostático não houve diferença entre as proporções: Idade (grupos I2 e I3) versus PSA (grupos P3 e P4) (p=1,000); Escore de Gleason (grupos G2 e G3) versus PSA (grupos P3 e P4)(p= 0,615); não houve correlação significativa entre: Idade (I1) versus PSA (P1) (p=0,265) isto também pode ter sido devido a idade mínima dos nossos casos; e Idade (I1) versus Escore de Gleason (G1) (p=0,925); houve correlação significativa entre: Escore de Gleason (G1) versus PSA (P1) (p=0,016). Nossos resultados permitem concluir que o PSA não pode ser utilizado como marcador preciso para o diagnóstico do câncer de próstata, nem para o diagnóstico diferencial deste com hiperplasia prostática benigna
98

Zušlechťování bioplynu metodou PSA / Upgrading biogas by PSA

Krhut, Štěpán January 2017 (has links)
This work deals with bio gas cleaning by a PSA method and modernizing of a laboratory unit. Raw bio gas contains many unwanted elements like carbon dioxide mostly which lowers its energy potential then. To extend the possibilities of usage of bio gas it is necessary to remove such elements. One of the well-known method for eliminating CO2 out of the bio gas is the method called Pressure Swing Adsorption (PSA). This work describes PSA method and compares it with other methods for cleaning the bio gas. In the following part of my work I am introducing the original laboratory PSA unit which is placed in the laboratory of UPI institution for research purposes. The modernization of the method was made by changing the manual valves for electromagnetic ones and there was also designed a new control system unit for two control modes. For manual and for automatic. The essential function is based on remote controlling the valves either by switches or by a program. The electric control panel was created for such required modes. The automated process was controlled by Arduino programming platform which was integrated into the panel. In the case of the next measurement and reading there was created a detailed description for user on how to operate the control panel and also the comments for control program of automatization.
99

<b>Development of a Potential Facility Risk Index for Nuclear Safety and Security</b>

Joeun Kot (18370179) 16 April 2024 (has links)
<p dir="ltr">Risk assessment involves analyzing potential accident scenarios to identify hazards and assess associated risk factors. Nuclear safety and security share the common goal of protecting against radiation exposure. However, they have developed separately, each with their own distinct risk assessment methodologies. As a result, there is a need for a comprehensive risk assessment method that covers both safety and security aspects. This thesis proposes a methodology that integrates risk assessment approaches for nuclear safety and security to address the gap in the current development of their risk assessment methodologies.</p><p dir="ltr">The proposed methodology applies the existing probabilistic risk assessment (PRA) methodology to the PFRI (Potential Facility Risk Index), originally developed to evaluate quantitative nuclear security risks, to enable the inclusion of safety risks in the assessment. The PFRI framework and methodology are modified to ensure that the PFRI score accurately reflects the overall risk of the facility for both nuclear safety and security. The facility-based approach of the existing PFRI is maintained to ensure a comprehensive assessment of the research reactor.</p><p dir="ltr">To achieve the goal of developing a comprehensive risk assessment method, the traditional PRA tools, such as event tree analysis (ETA) and fault tree analysis (FTA), are utilized in combination with the modified PFRI methodology. In addition, the consequence analysis method of PFRI is changed using the MACCS, which is commonly used for consequence analysis in PRA. The modified methodology is then used to conduct a risk assessment for the PFRI by setting safety and security scenarios at a hypothetical nuclear facility. The results demonstrate that the modified PFRI can provide a reasonable traditional risk unit and enable the comparison of risks from both safety and security aspects.</p><p dir="ltr">The final goal of this study is to develop the PFRI to determine the overall risk of the facility, considering both nuclear safety and security aspects. The PFRI score is utilized as a quantitative measure to show the total risk associated with hypothetical nuclear facility, providing a comprehensive understanding of its safety and security. By developing a methodology that integrates risk assessment approaches for nuclear safety and security, this thesis contributes to the improvement of the risk assessment methodology for nuclear facilities.</p>
100

HOST-MICROBIOME INTERACTIONS AND REGULATION OF THE IMMUNE SYSTEM

Alvarez Contreras, Carlos Alberto 22 January 2021 (has links)
No description available.

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