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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.
11

Effect of preharvest UV-treatment on shelf life of fruits and vegetables

Obande, Matthew A. January 2010 (has links)
The benefits of low UV dose treatment of horticultural produce – also known as hormetic treatment - have been attested to in numerous studies conducted over the last 15 years. However, commercial growers have not adopted the concept of hormesis. With increasingly stringent controls on the use of fungicides and other chemical agents the time has come to examine how hormetic treatment might be applied in the horticulture sector. The objectives of this work were firstly, to confirm UV-induced hormetic effects applied postharvest for a number of different types of produce, namely, tomatoes, broccoli, strawberries and mangoes. Secondly, to evaluate the use of rollers to ensure full surface treatment of produce, and thirdly to evaluate the possibility of treating produce preharvest. In order to investigate surface UV dose distributions, a polystyrene sphere (Diameter 70 mm) was used to simulate fruits such as tomatoes, apples, peaches etc., that have an approximately spherical form. Biodosimetry based on spores of Bacillus subtilis was employed to experimentally determine UV doses and to compare the results obtained with theoretical predictions. Good agreement was obtained and the modelling approach was extended to other types of produce. This showed the amenability of mechanical rollers to ensure full surface treatment of produce. Postharvest treatment of produce was carried using conventional low intensity UV sources principally emitting at 254 nm and also a commercially available high energy pulsed UV source. Treatment using the conventional UV source was carried out on mechanical rollers within a UV cabinet designed for this work at a fixed distance from the source and at an intensity of 1000 μW/cm2. A 5 minute conventional UV treatment of tomatoes was approximately comparable to fruit given a 3-pulsed treatment using the pulsed source (507 J/pulse of polychromatic light). The colour and texture of both groups of fruit were significantly maintained as compared with controls. The treated tomatoes also showed a significant increase in the ascorbic acid levels during storage. Similarly, a 15 minute conventional UV treatment of broccoli heads was comparable to heads given a 10-pulsed treatment using the pulsed source. Where both treatments gave rise to a statistically significant retention of green colour of treated broccoli. In addition, mangoes given a 10 minute conventional UV treatment were comparable to fruit given a 20-pulsed treatment using the pulsed source with both treatments leading to maintenance of texture as compared to control fruit. This confirmed the UV-hormetic effects. The effects of conventional and pulsed treatments are compared and discussed. Preharvest treatment of tomatoes and strawberries was carried out in commercial glasshouses. Doses of either 3 or 8 kJ/m2 were delivered to the fruits using a treatment device designed for the work, which delivered a combined intensity of 2000 μW/cm2 from two low pressure UV sources. The treated tomatoes showed a delay in development of colour as measured on the vine and after picking. Picked tomatoes were inoculated with P. digitatum and C. gloeosporioides and the results obtained showed a significant inhibition of the development of the fungi in the treated fruit during the storage period. These results suggest that the beneficial response shown by the preharvest treatment is not a localised one but a systematically induced resistance observable throughout the treated plant. This was shown by monitoring tomato fruits on treated plants which themselves where not directly exposed to the UV light. The two doses elicited different responses in the treated strawberries, with the 8 kJ/m2 dose causing the fruit to redden significantly faster than the 3 kJ/m2 treated fruits and controls. This could have significant nutritional benefit as the red colour of strawberries has been correlated with anthocyanin levels. On the other hand, treatment at the lower UV dose led to a lag in colour development. The amenability of the equipment utilised for commercial application is discussed.
12

On being a person through time : the value of life extension and the ethics of aging intervention

Horrobin, Steven January 2008 (has links)
In context of the possibility of aging interventions leading to significant or radical extensions in human lifespan, this thesis seeks primarily to address the question of the value of life’s continuance to persons, as the most fundamental motivating factor behind the project specifically to extend life beyond the classic endogenous maximum span. In so doing, its chief focus will therefore be upon the nature of persons themselves, especially in terms of the structure of personhood as a category of being. Much of the investigation will therefore be of an ontological nature, with the nature of value itself, and the relation of value both to persons in particular, and living organisms and the natural realm in general, being a critical theme. The consideration of the latter cases is necessitated by the requirement to analyse the structure of persons in whole, and especially because the primary positive thesis is that persons are processes which are motivated at base by a conative driver which itself is constitutive of their being at all. The analysis of the nature and function of this primary driver of persons as processes, in context of its relation to their secondary instrumental valuation of themselves, which lies at the core of the thesis will generate the conclusion that life’s continuance constitutes an inalienable value to persons that is profound to the degree that it obtains irrespective even of their own evaluative judgements. This analysis suggests a grounding in the question of the manner in which persons arise from the category of other living organisms in general, and the manner in which these arise from the background matter in the universe. The latter will be analysed and the nature of the conative driver will be asserted to be a physical principle which is a defining condition of living organisms in general. Additionally, the analysis of the category of the natural will constitute a critical theme for other reasons, which involve the reliance by certain commentators in the discourse concerning the ethics of aging intervention and life extension upon assertions as to naturalness, and the ethics of human alteration of or interference with the natural, the sacred, the normal, and the given. These latter will be argued to constitute a cluster concept, which will be analysed and demonstrated largely to be lacking in soundness, validity and real cohesion. Further, common ethical arguments against the wisdom of radical life extension in the personal case will be analysed, and mostly found wanting. The core thesis represents a re-evaluation of the classic liberal concept of persons as selfconscious, autonomous, rational valuing agents. This classic analysis will be shown to be faulty in certain key respects, and a correction will be proposed along the lines mentioned above. The fact that these faulty aspects of the classic liberal position constitute key points of attack for conservative personhood theorists, and that the correction offered by the revised liberal version generates a picture of the stability of the value of persons to themselves (and therefore generally) that at least matches that of the various conservative positions (considered to be their main strength by their proponents), largely neutralises such critiques, as well as removes a key rationale for those opting for the conservative positions in their rejection of the general subjectivist liberal picture of personhood. The conservative conception of value in general, and the value of life and persons in particular is critiqued and found wanting. Aside from being commonly based upon a false conception of naturalness, in which supernatural entities, substances or beings are considered to operate, a significant aspect of the failure of this conservative picture arises from the false conception of persons as substantial in nature, or as substances. Accordingly, a critique of the concept of substance in universal ontology is conducted in the first section of the thesis, which will attempt to demonstrate the ontological primacy of process over substance.
13

Application of SCADA Data Monitoring Methodology and Reliability Analysis of Wind Farm Operational Data

Alavanja, Bojan January 2016 (has links)
Reliability of wind turbine components and maintenance optimisation are among the critical aspects of wind power development closely related to profitability and future development. The main reason for research in these areas is lowering the cost of energy production for wind power, specifically important in offshore environment. Continuous monitoring of specific wind turbine components can be valuable for wind farm operators and, subsequently, wind farm owners.  Also, health assessment of critical components can be useful in estimating the possibilities for life extension of wind turbines. Expensive Condition Monitoring Systems (CMSs) are not always available, particularly in older wind farms, and additionally installing CMSs on wind turbines is not always economically feasible. However, most of modern wind turbines are equipped with the Supervisory Control And Data Acquisition (SCADA) system which is recording 10-minute average values of parameters that depict operation of the turbine. That being said, SCADA data contains a vast amount of information that can be used for analysis of wind turbine components health. Therefore, this project will present an application of previously published methodology for SCADA data condition monitoring on real wind farm data. The goal of this project is to investigate on the possibilities of the SCADA monitoring methodology and what can be the added value of the application for wind farm operators, owners and other stakeholders. The methodology for condition monitoring through SCADA data was applied on real data gathered from two wind farms in Germany and one in the Netherlands. During the project the methodology had to be modified in order to ensure the best possible industrial application. Results of the project showed that the SCADA data condition monitoring approach is not capable of predicting failures. However, the technique has been proven successful for detecting the changes of trends in dependencies of working parameters, specifically monitoring parameters related to the turbine generators. Continuously monitoring the dependencies of working parameters can be used as an additional source of information for maintenance scheduling and assessment of components health. The approach presented in this paper can be valuable to asset managers and wind farm owners.
14

Carbon Dioxide Treatment on Strawberry Fruit Prep and Its Effect on Shelf Life

Dawson, Bryan Sterling 01 December 2018 (has links)
This research evaluates the effectiveness of using carbon dioxide (CO2) pressurization to extend strawberry fruit prep shelf life for the eventual use in yogurt applications. In this experiment, CO2 treatments of 5, 15, and 25 pounds per square inch were used as a processing step to inactivate microorganisms, which in turn could aid in the preservation and maintenance of product quality during storage thus improving consumer acceptance of the yogurt. Microbial levels of the fruit prep treatments were monitored over a six-week period by enumerating aerobic plate counts and yeast and mold levels. The color, pH, and texture of the treatments were also evaluated throughout the duration of the study. Sensory attributes of the product were evaluated by formal sensory panel at the beginning of the study to gather consumer feedback on potential changes introduced by the treatment to the finished product. For sensory analysis, the different CO2 treatments of fruit prep were mixed with plain yogurt and given to panelists. The different treatments were taken from one homogenous mixture of fruit prep and then were randomly divided into five different treatment groups: a control group, a thermally processed group, and the three different pressure levels of CO2. Results from the experiment showed that carbonation does not negatively impact product overall acceptability. Shelf life results showed that CO2 treatments are not effective in maintaining or extending the shelf life of strawberry fruit prep when compared to a thermal treatment.
15

Transhumanism: An Ontology of the World's Most Dangerous Idea

Ross, Benjamin David 05 1900 (has links)
Transhumanism is the name given to the cultural and philosophical movement which advocates radical human technological enhancement. In what follows, I use perspectives drawn from existential philosophy to problematize transhumanists' desire to recast human finitude as a series of technical problems with technical solutions. The ontological account of transhumanism offered here questions the assumed benefit and inevitability across six chapters. Following an introductory chapter, Chapter 2 introduces the key players, and present the philosophy of transhumanism and the opposing view of bioconservativism. Chapter 3 offers a narrative of transhumanism beginning with its mythical antecedents, and proceeds to describe the emergence of contemporary transhumanist institutions. Chapter 4 focuses on the challenge that transhumanists Aubrey de Grey and Ray Kurzweil present to mortality. The chapter asks whether human immortality is a coherent idea, and consider the consequences of achieving a data-driven amortality. Chapter 5 continues the analysis of transhumanism as it challenges limits to knowledge (ignorance), and limits to well-being (suffering). Ray Kurzweil is presented as a key figure of transhumanist thought, along with David Pearce, who desires to eradicate suffering through genetic engineering. The hubris of transhumanism is viewed through the lens of Friedrich Nietzsche in chapter 6. Nietzsche's critique of the "last human" is interpreted in terms of transhumanist thought, and a role for the philosopher in the context of transhumanism is presented. Finally, chapter 7 offers Buddhism as an alternative response to suffering. This chapter profiles "Buddhist Transhumanists," and consider what connection transhumanism has with Buddhism's philosophy of impermanence.
16

HARNESSING TRANSTHYRETIN TO ENHANCE THE IN VIVO HALF-LIFE OF HUMAN INTERLEUKIN-2 (IL-2)

Liu, Fang 01 January 2021 (has links) (PDF)
Protein therapeutics are available as cytokines, clotting factors, enzymes, hormones, growth factors, antibodies et al. They have been shown to be effective in treating a variety of important human diseases. Since human insulin was approved as the first recombinant protein therapeutic, this field has experienced rapid growth. One of the biggest challenges for protein therapeutics in clinical application is their short half-life. Except for monoclonal antibodies, which have serum half-life for weeks, most of the protein therapeutics have half-lives ranging from minutes to hours. Kidney filtration, proteasome degradation and liver metabolism are the main factors that attribute to their short half-lives. The short half-life of protein therapeutics requires a higher dose or frequent application to maintain therapeutic concentration over a certain period. However, higher dose is easy to cause large plasma concentration fluctuation, which is easy to cause side effects. Most of protein therapeutics are not orally bioavailable. Frequent application will increase the burden of patients, affect their life quality, and reduce patient compliance. Thus, it is important to generate long-lasting therapeutics with improved pharmacokinetic properties. The current half-life extension approaches for protein therapeutics include PEGylation, albumin fusion or binding and fusion to an immunoglobulin Fc region. Their primary aim is to increase the size of biotherapeutics or to implement recycling by the neonatal Fc receptor (FcRn). However, the half-life extension by PEGylation, albumin fusion or Fc fusion is at the cost of binding affinity reduction. And the increase of size has limited their application in the field of anticancer agents where tumor penetration is required. Noncovalent albumin binding using albumin binding ligands such as fatty acids could maintain the small size and binding affinity. However, it would increase hydrophobicity, therefore is not suitable for protein therapeutics with low solubility. Here, we present a new approach for half-life extension for biotherapeutics. Human interleukin 2 (IL-2), a low solubility cytokine, was used as a model protein. By conjugating IL-2 with a hydrophilic small molecule that binds reversibly to the serum protein transthyretin, we enhanced its circulation half-life in rodents while maintained its in vitro bioactivity. To the best of our knowledge, this is the first demonstration of a successful approach that harnesses a small molecule in extending the circulation half-life of a protein while at the same time maintains the small size and hydrophilicity.
17

Impact of Induced Defects on Rotor Life Assessment

Whitney-Rawls, Ashley Winfield 15 December 2010 (has links)
No description available.
18

Mitigating adverse impacts of increased electric vehicle charging on distribution transformers

Jain, Akansha 12 May 2023 (has links) (PDF)
There is a growing interest in electric transportation, and the number of electric vehicles (EVs) is increasing. The resulting increase in EV charging power demand has an adverse impact on the existing power grids, especially the distribution transformers. The repeated and continued overloading caused by EV charging can significantly reduce their operational life. This dissertation aims to comprehensively study the adverse impacts of EV charging on distribution transformers and provide robust and practical solutions to mitigate it. A typical North American secondary distribution system with different EV penetration levels and four realistic residential EV charging scenarios are used for the analyses. The IEEE Standard C57.91-2011 is used to quantify transformer life under different scenarios and to validate the efficacy of the proposed overloading mitigation strategies. It is observed that EV charging can have a significant impact on the life of distribution transformers. To mitigate the impact of EV charging on the distribution transformer, first, a practical solution based on reactive power compensation is proposed. The method is based on reducing the over- all transformer losses by providing a component of the residential reactive power demand through non-unity power factor operation of the EV charger. A centralized recursive control structure is proposed to compute and communicate the required reactive power values to the individual EVs. It is shown that the proposed technique increases the distribution transformer’s life by an average of nearly 47% in all four scenarios considered. Moreover, the proposed controller’s structure makes it effective even on low-bandwidth, high-latency communication networks. To verify this, the proposed controller’s stability under communication delays and its robustness against potential communication failures is also validated. This research also studies potential concerns about the charger’s reliability by non-unity power factor operation. Accordingly, an alternative overloading mitigation strategy is also proposed based on fixed charging current magnitude. This second method is shown to be more effective in reducing transformer overloading at the cost of a marginal decrease in the charging rate. Lastly, a high-level overview of the existing vehicle-to-grid communication standards is presented to provide a better context for practical implementation and identify potential challenges.
19

Selection and characterization of bispecific ADAPT molecules for enhanced biodistribution in cancer therapy

Borin, Jesper January 2020 (has links)
Established biopharmaceuticals such as antibodies and derivatives thereof are relatively large. In cancer therapy, this creates a steep drug concentration gradient within tumors, leaving cells far from blood vessels effectively untreated. Continuous pseudo treatments should foster the development of drug resistance and might lead to eventual disease relapse. Drug concentration gradients can be operationalized as tissue penetration efficiencies, which are functions of molecular size. However, small particles are also subject to potent renal clearance, collapsing the therapeutic window beyond clinical applications. In this master’s thesis, spatial bispecificity was engineered into a single albumin binding domain (ABD). Resulting ABD derived affinity proteins (ADAPTs) are saved from urinary excretion by the grace of HSA, but in the more static microenvironment of tumors, following HSA dissociation, they are capable of tissue penetration efficiencies bestowed only upon smaller particles. To this end, phage display was used to raise ADAPTs against the cancer associated proteins human epidermal growth factor receptor 2 (HER2) and carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), but also the inflammation marker C-reactive protein (CRP). Via Sanger sequencing, 9 variants were picked for protein production and characterization, among which two spatially bispecific binders were found. ADAPTs were also evaluated for aggregation tendencies, structural conformity to library design, and thermal stability. One ADAPT, binding HER2, passed all tests of initial characterizations. Deep sequencing was used to analyze selection output, from which many more binders should be screened in future experiments. / Etablerade bioläkemedel liksom antikroppar och deras derivat är relativt stora protein. Som cancerterapeutiska skapar de således branta koncentrationsgradienter utgående från tumörpenetrerande blodkärl. Detta riskerar att lämna vissa cancerceller utanför det terapeutiska fönstret. Det svaga selektionstryck som således verkar i tumörperiferin fostrar cancerceller till att utveckla resistens mot detsamma. Koncentrationsgradienten beror på proteinets vävnadspenetrarande förmåga, vilken är en funktion av proteinets storlek. Mindre proteiner borde därmed lättare ackumuleras i hela tumören och förebygga resistensutveckling. Problemet med små proteiner är deras mycket korta halveringstid i serum, en följd av relativt obehindrad filtrering ut i urinen via njurarna. I det här examensarbetet utvecklades rumsbispecifika bindare av cancerassocierade protein med hjälp av fagdisplayselektioner från ett proteinbibliotek baserat på en enda albuminbindande domän (ABD). Resulterande ABD deriverade affinitetsprotein (ADAPT) undkommer ovan nämnda filtrering tack vare sin naturligt starka interaktion med humant serumalbumin (HSA). I den mer långsamt flödande tumörmikromiljön tillåts ADAPTerna efter albumindissociation sedan utöva en bland bioläkemedel överlägsen vävnadspenetration. Tre parallella selektionsspår utfördes mot de cancerassocierade målproteinerna human epidermal growth factor receptor 2 (HER2) och carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) samt den utsöndrade inflammationsmarkören C-reaktivt protein (CRP). Via Sangersekvensering kunde flera kandidater identifieras. Bland 6 karakteriserade ADAPTer uppvisade samtliga hög HSA-affinitet, tre konstaterades interagera specifikt med sitt målprotein, och två verkade binda även rumsbispecifikt. ADAPTer utvärderades även för sin benägenhet att bilda aggregat, strukturell överensstämmelse med experimentell design, och värmestabilitet. Endast en bindare, mot HER2, klarade sig genom alla prövningar som proteinkarakteriseringen innebar utan underkänt. Även en högparallel sekvensering utav selektionsresultat utfördes, men utanför de tidsramar som tillät ytterligare karakterisering.
20

Det moderna plagget för alla : Cirkulära metoder för att skapa hållbara jeans för människa och miljö / The modern garment for everyone : Circular methods for creating sustainable jeans for man and the environment

Björklund Engström, Vendela, Alfredsson, Beatrice January 2022 (has links)
Syftet är att granska cirkulära textila hållbara metoder inom fyra olika jeansvarumärken. Genom en tematisk analys ska deras skilda tillvägagångssätt till sina cirkulära koncept att presenteras. Dessa samlade cirkulära koncept är avsedda till nystartade jeansföretag, och ska utvärdera samt diskuteras huruvida dessa är lämpliga att implementera för deras verksamhet eller ej. Det nystartade jeansföretagets ambition är att implementera cirkulär ekonomi som för dem i dagsläget är svårt att utveckla på egen hand. De vill vara en del av den cirkulära ekonomin och hela dess verksamhet har sin utgångspunkt i att deras produkter ska bäras år in och år ut med så lång livslängd som det är möjligt. Deras vision är att vara ett cirkulärt företag, dock finns en avsaknad av viktiga tillhörande förutsättningar för att kunna implementera den cirkulära ekonomin. Dessa förutsättningar är olika typer av resurser som är avgörande för att kunna utveckla en cirkulär ekonomi. Dessa resurser är bland annat kunskap, medarbetarstyrka och kapital. Datainsamlingen består av granskning av fyra hållbarhetsrapporter samt en intervju med ett jeansföretag. Data har analyserats med avseende på vad som kan vara tillämpligt för att bli ett mer cirkulärt företag. Vikten av publicitet och marknadsföringskampanjer tas upp som en viktig aspekt i att bibehålla företaget hållbart ur en ekonomisk och cirkulär synvinkel. Som rekommenderade åtgärder diskuteras återvinningsprojekt, gränsöverskridande samarbeten samt kit utveckling. / The purpose is to examine circular textile sustainable methods within four different jeans brands. Through a thematic analysis, their different approaches to their circular concepts are presented. These collective circular concepts are intended for a start-up jeans company, and evaluate and discuss whether these are suitable to implement for their business or not. The start-up jeans company's ambition is to implement a circular economy which for them is currently difficult to develop on their own. They want to be part of the circular economy and its entire business is based on their products being worn year in and year out with as long a lifespan as possible. Their vision is to be a circular company, however there is a lack of important associated conditions to be able to implement the circular economy. These conditions are different types of resources that are crucial to be able to develop a circular economy. These resources include knowledge, staff capacity and capital. The data collection consists of reviewing four sustainability reports and an interview with a jeans company. Data have been analyzed with regard to what may be applicable to become a more circular company. The report has ended up in this conclusion; the importance of publicity and marketing campaigns is addressed as an main aspect in maintaining the company sustainably from an economic and circular point of view. Recommended measures are recycling projects, cross-border collaborations and kit development.

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