Dissertations / Theses on the topic 'Heart formation'
To see the other types of publications on this topic, follow the link: Heart formation.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Heart formation.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Vos, Marc Adriaan. "New observations to identify abnormal impulse formation in the intact heart." Maastricht : Maastricht : Datawyse ; University Library, Maastricht University [Host], 1989. http://arno.unimaas.nl/show.cgi?fid=5552.
Full text
2
Song, Yuntao. "Epigenetic repression of retinoic acid responsive genes for cardiac outflow tract formation." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563295948947138.
Full text
3
Thompson, Rosemary. "Some elements of a formation program for the religious of the Sacred Heart." Theological Research Exchange Network (TREN), 1996. http://www.tren.com.
Full text
4
Caporilli, Simona. "Investigating the mechanisms of cardiac patterning and morphogenesis using a heart formation assay." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/54174/.
Full textAbstract:
Using
5
Donaldson, W. Steven. "The sedimentology, stratigraphy and diagenesis of the Upper Cretaceous Bad Heart Formation, NW Alberta." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/NQ40253.pdf.
Full text
6
Sneesby, Kyra, and n/a. "Gene Expression in Embryonic Chick Heart Development." Griffith University. School of Biomolecular and Biomedical Science, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030924.153514.
Full textAbstract:
Establishment of the biochemical and molecular nature of cardiac development is essential for us to understand the relationship between genetic and morphological aspects of heart formation. The molecular mechanisms that underly heart development are still not clearly defined. To address this issue we have used two approaches to identify genes involved in early chick cardiac development. Differential display previously conducted in our laboratory led to the identification of two gene fragments differentially expressed in the heart that are further described in this thesis. The full-length cDNA sequence of both eukaryotic translation initiation factor-2b (eIF-2b) and NADH cytochrome b5 reductase (b5R) were isolated using library screening. The upreglation of these genes during heart development is expected given the heart is the first functional organ to form in vertebrates and protein synthesis and cell metabolism at this stage of development is maximal. Limitations in the differential display approach led to the development and optimisation of a subtractive hybridisation approach for use with small amounts of cells or tissue. To focus on cardiac gene expression during the initial phases of heart development, subtractive hybridization was performed between the cardiogenic lateral plate mesoderm of Hamburger and Hamilton stage 4 embryos and the heart primordia of stage 9 embryos. Of the 87 independent clones identified by this procedure, 59 matched known sequences with high homology, 25 matched unknown expressed sequence tag (EST) sequences with high homology, and 3 did not match any known sequence on the database. Known genes isolated included those involved in transcription, translation, cell signalling, RNA processing, and energy production. Two of these genes, high mobility group phosphoprotein A2 (HMGA2) and C1-20C, an unknown gene, were chosen for further characterisation. The role of each gene in early chick heart development and indeed development in general, was addressed using techniques such as in situ hybridisation, transfection analysis, in ovo electroporation and RNAi. HMGA2 is a nuclear phosphoprotein commonly referred to as an architectural transcription factor due to its ability to modulate DNA conformation. In keeping with this function, HMGA2/GFP fusion protein was shown to localise to the nucleus and in particular, the nucleolus. In situ hybridisation analysis suggested a role for HMGA2 in heart and somite development. HMGA2 expression was first detected at HH stage 5 in the lateral plate mesoderm, a region synonymous with cells specified to the cardiac fate. HMGA2 was also strongly expressed in the presomitic segmental plate mesoderm and as somites developed from the segmental plate mesoderm, the expression of HMGA2 showed an increasingly more restricted domain corresponding to the level of maturation of the somite. Restriction of HMGA2 expression was first detected in the dorsal region of the epithelial somite, then the dorsomedial lip of the dermomyotome, and finally the migrating epaxial myotome cells. The novel intronless gene, C1-20C, predicts a protein of 148 amino acids containing a putative zinc finger binding domain and prenyl binding motif. Zinc binding assays showed that the zinc finger domain of C1-20C/MBP fusion protein bound over six times the quantity of zinc compared to MBP alone, although not in a 1:1 stoichiometric molar ratio. C1-20C/GFP fusion protein was shown to localise to as yet unidentified intracellular cytoplasmic vesicular compartments. These compartments did not colocalise with the endosome/lysosome pathway, aparently ruling out a role for C1-20C in protein trafficking, recycling or degradation. Expression of C1-20C in the chick embryo suggests a possible role in heart and notochord development and preliminary results using siRNA suggest that C1-20C is involved in normal heart looping.
7
Sneesby, Kyra. "Gene Expression in Embryonic Chick Heart Development." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/367647.
Full textAbstract:
Establishment of the biochemical and molecular nature of cardiac development is essential for us to understand the relationship between genetic and morphological aspects of heart formation. The molecular mechanisms that underly heart development are still not clearly defined. To address this issue we have used two approaches to identify genes involved in early chick cardiac development. Differential display previously conducted in our laboratory led to the identification of two gene fragments differentially expressed in the heart that are further described in this thesis. The full-length cDNA sequence of both eukaryotic translation initiation factor-2b (eIF-2b) and NADH cytochrome b5 reductase (b5R) were isolated using library screening. The upreglation of these genes during heart development is expected given the heart is the first functional organ to form in vertebrates and protein synthesis and cell metabolism at this stage of development is maximal. Limitations in the differential display approach led to the development and optimisation of a subtractive hybridisation approach for use with small amounts of cells or tissue. To focus on cardiac gene expression during the initial phases of heart development, subtractive hybridization was performed between the cardiogenic lateral plate mesoderm of Hamburger and Hamilton stage 4 embryos and the heart primordia of stage 9 embryos. Of the 87 independent clones identified by this procedure, 59 matched known sequences with high homology, 25 matched unknown expressed sequence tag (EST) sequences with high homology, and 3 did not match any known sequence on the database. Known genes isolated included those involved in transcription, translation, cell signalling, RNA processing, and energy production. Two of these genes, high mobility group phosphoprotein A2 (HMGA2) and C1-20C, an unknown gene, were chosen for further characterisation. The role of each gene in early chick heart development and indeed development in general, was addressed using techniques such as in situ hybridisation, transfection analysis, in ovo electroporation and RNAi.
HMGA2 is a nuclear phosphoprotein commonly referred to as an architectural transcription factor due to its ability to modulate DNA conformation. In keeping with this function, HMGA2/GFP fusion protein was shown to localise to the nucleus and in particular, the nucleolus. In situ hybridisation analysis suggested a role for HMGA2 in heart and somite development. HMGA2 expression was first detected at HH stage 5 in the lateral plate mesoderm, a region synonymous with cells specified to the cardiac fate. HMGA2 was also strongly expressed in the presomitic segmental plate mesoderm and as somites developed from the segmental plate mesoderm, the expression of HMGA2 showed an increasingly more restricted domain corresponding to the level of maturation of the somite. Restriction of HMGA2 expression was first detected in the dorsal region of the epithelial somite, then the dorsomedial lip of the dermomyotome, and finally the migrating epaxial myotome cells. The novel intronless gene, C1-20C, predicts a protein of 148 amino acids containing a putative zinc finger binding domain and prenyl binding motif. Zinc binding assays showed that the zinc finger domain of C1-20C/MBP fusion protein bound over six times the quantity of zinc compared to MBP alone, although not in a 1:1 stoichiometric molar ratio. C1-20C/GFP fusion protein was shown to localise to as yet unidentified intracellular cytoplasmic vesicular compartments. These compartments did not colocalise with the endosome/lysosome pathway, aparently ruling out a role for C1-20C in protein trafficking, recycling or degradation. Expression of C1-20C in the chick embryo suggests a possible role in heart and notochord development and preliminary results using siRNA suggest that C1-20C is involved in normal heart looping.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Biomedical Sciences
Full Text
8
Ragan, Sarah E. "Peering into the heart of galactic star formation : a detailed characterization of infrared-dark clouds /." [S.l. :] University of Michigan, 2009. http://adsabs.harvard.edu/abs/2009PhDT........12R.
Full text
9
Blum, Kevin Matthew. "Mechanisms Guiding Neotissue Formation and Remodeling in Tissue Engineered Vascular Grafts." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1614871166400724.
Full text
10
Barnum, Martin J. "The eucharistic liturgy as a school of spiritual formation." Online full text .pdf document, available to Fuller patrons only, 2002. http://www.tren.com.
Full text
11
Gilmore, William Samuel. "A study of molecules involved in the regulation of the growth of haematopoietic cells and heart muscle cells in culture." Thesis, University of St Andrews, 1986. http://hdl.handle.net/10023/14970.
Full textAbstract:
The description of the molecular events responsible for the control of cell division and differentiation is, currently, one of the major goals of molecular and cellular biologists. Cell and tissue culture techniques have proved to be promising laboratory tools for the study of the regulators of cellular growth and differentiation. Most cells in culture require specific polypeptide growth factors which are supplied by the addition of a complex biological fluid such as serum or, in some instances, by the cells themselves. These growth factors usually act on their target cell via a membrane receptor to which they bind. The events which occur after the growth factor binds to the membrane receptor have not been fully described, but the phosphorylation of tyrosine residues in certain proteins has been observed. A study was made of the polypeptide growth factors responsible for the growth and differentiation of haematopoietic cells in vitro. These growth factors, called colony - stimulating factors (C.S.F.'s) were prepared from human placental conditioned medium, giant cell tumour conditioned medium and pokeweed mitogen stimulated spleen conditioned medium. A C.S.F. from human placental conditioned medium was radioiodinated and the binding of the labelled growth factor to an anti-C.S.F. antiserum was studied. The binding studies indicated that a purer C.S.F. preparation and/or a more specific antiserum was necessary in order to establish a radioimmunoassay for C.S.F. The C.S.F.'s from giant cell tumour conditioned medium were purified by ultrafiltration, hydrophobic - interaction chromatography, gel filtration and thiolpropyl - sepharose 6B chromatography. Two peaks of biological activity were observed on gel filtration. One of these peaks gave an apparent MW of 63,000 and the other peak gave an apparent MW of 30,200. The C.S.F. from pokeweed mitogen stimulated spleen conditioned medium was labelled with peroxidase and the binding of the labelled-C.S.F. to bone marrow cell membranes studied. The labelled-C.S.F. bound to the membranes and the binding exhibited a linear relationship with membrane protein content. Also a defined growth medium for chick embryonic heart cells was developed. These cells were observed to differentiate from primitive foetal cells into mature "adult-type" cells. The cells grew as a monolayer, had spontaneous activity and were seen to beat.
12
Komatsu, Koji. "Meltrin β expressed in cardiac neural crest cells is required for ventricular septum formation of the heart." Kyoto University, 2007. http://hdl.handle.net/2433/135667.
Full text
13
Larsson, Annika. "Medin amyloid - a matter close to the heart : Studies on medin amyloid formation and involvement in aortic pathology." Doctoral thesis, Uppsala universitet, Institutionen för genetik och patologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9275.
Full textAbstract:
Amyloidoses are a group of protein misfolding diseases characterized by deposits of insoluble fibrillar protein aggregates. Medin amyloid, which is the focus of this thesis, appears in the media of the thoracic aorta in nearly all individuals over 50 years. The fibrils are derived from a 50 amino acid residue fragment of the precursor protein lactadherin. How medin amyloid arises is unknown, but in paper I we demonstrated, with immunohistochemical and in vitro binding experiments, that both lactadherin and medin interact with elastin, implying that the elastic fibre is central in amyloid formation. In paper II, we further showed that the last 18-19 amino acid residues constitute the amyloid-promoting region. In paper III, the consequence of medin deposition was investigated. Aortic specimens from patients with thoracic aorta aneurysm and dissection were examined for medin content. The tissue findings indicated that the two disease groups contained more medin oligomers than normal aortas. Interestingly, recent reports demonstrate that the toxicity of amyloid proteins is attributed to prefibrillar oligomeric aggregates rather than to mature fibrils. In support of this finding, we observed that prefibrillar medin, in contrast to medin fibrils, was toxic in cell culture. Amyloid formation is a nucleation-dependent process. Addition of preformed fibrils to an amyloid protein solution dramatically accelerates fibrillation, a phenomenon called seeding. In paper IV, serum amyloid A-derived (AA) amyloid was found co-localized with medin deposits in the aorta. In vitro, medin fibrils enhanced the formation of AA fibrils, indicative of a seeding mechanism. The data are of great importance as they suggest that one type of amyloid is capable of inducing fibrillation and deposition of another amyloid type. In conclusion, the results of this thesis shed light on how medin is formed, the function of lactadherin and the consequences of medin deposition for aortic pathology.
14
Togi, Kiyonori. "A role of Hand1/eHAND in the dorso-ventral patterning and interventricular septum formation in the embryonic heart." Kyoto University, 2004. http://hdl.handle.net/2433/145274.
Full text
15
Peterson, Sandra Rubinstein. ""One heart, many souls" the National Council of Jewish Women and identity formation in St. Louis, 1919-1950 /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5567.
Full textAbstract:
Thesis (Ph. D.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on July 28, 2009) Includes bibliographical references.
16
Hillman-Breckner, Vicki. "The heart set on pilgrimage a model for placing spiritual formation central in the ministry of the local church /." Online full text .pdf document, available to Fuller patrons only, 2000. http://www.tren.com.
Full text
17
Ingvarsdottir, Hafdis. "The heart of the matter : the nature, use, and formation of teachers' subjective theories in secondary schools in Iceland." Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269113.
Full text
18
Lencinas, Sanabria Alejandro. "Arsenic and Olfactomedin-1 Regulation of Epithelial to Mesenchymal Cell Transition (EMT) in Heart Valve Development." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/217109.
Full textAbstract:
This dissertation centers on the study of epithelial to mesenchymal cell transition (EMT) in the heart model of valve development. EMT is a process used by specific cells to invade adjacent matrix in order to differentiate into a three-dimensional structure. The first section of the project includes a study on the effects of inorganic arsenic on EMT and therefore the environmental concerns produced by deleterious effects on EMT. The second section focuses on the discovery of an intrinsic regulator of EMT, olfactomedin-1 (OLFM1). The discovery of a novel regulator of EMT in the atrioventricular canal is interesting, by itself, as it allows us to better understand the intrinsic molecular regulation of EMT in valve formation of the heart. The activity of this protein, as a regulator of cell invasion, identifies an important checkpoint in EMT. Because OFLM1 is conserved across many species, including humans, it may be a common or shared regulator of all types of EMT including cancer. Therefore, OLFM1 represents a promising new target for an anti-cancer agent as well as a potential clinical inducer of EMT to repair congenital heart disease that include valve defects.
19
Basra, J. "A study of free radical formation in liver and heart tissue by alkylaminoanthraquinone antitumour agents based on mitozantrone and doxorubicin." Thesis, De Montfort University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371062.
Full text
20
Ernst, Kati [Verfasser]. "Heart over mind – an empirical analysis of social entrepreneurial intention formation on the basis of the theory of planned behaviour / Kati Ernst." Wuppertal : Universitätsbibliothek Wuppertal, 2012. http://d-nb.info/1022899309/34.
Full text
21
Schlick, Susanne [Verfasser], Wolfram-Hubertus [Akademischer Betreuer] Zimmermann, Ralf [Gutachter] Dressel, Stefan [Gutachter] Luther, Thomas [Gutachter] Meyer, Rüdiger [Gutachter] Behr, and Antje [Gutachter] Ebert. "Fibroblast-Cardiomyocyte Cross-Talk in Heart Muscle Formation and Function / Susanne Schlick ; Gutachter: Ralf Dressel, Stefan Luther, Thomas Meyer, Rüdiger Behr, Antje Ebert ; Betreuer: Wolfram-Hubertus Zimmermann." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1177361744/34.
Full text
22
Swinarski, Marie. "PCP-driven cardiac remodeling couples changes in actomyosin tension with myocyte differentiation." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17775.
Full textAbstract:
Im Zuge der frühen embryonalen Herzentwicklung entstehen ausgehend von einem einfachen Herzschlauch zwei deutlich voneinander getrennte Herzkammern. Die Kardiomyozyten des Atriums und Ventrikels weisen spezifische Eigenschaften auf, die sich morphologisch wie auch funktionell auf das Herz auswirken. Veränderungen in der Gewebsarchitektur werden hauptsächlich durch Zellinterkalation und kollektive Zellmigration erreicht. Viele Studien zeigen, dass der Wnt/PCP-Signalweg eine essentielle Rolle in der Regulation dieser Bewegungen einnimmt. Die Daten dieser Studie belegen, dass die nicht-kanonischen Liganden Wnt11 und Wnt5b sowie die Kernkomponenten des PCP Signalweges Fzd7, Vangl2, Dvl2 und Pk1 an der Steuerung der Reorganisation der Kardiomyozyten während der Kammerbildung beteiligt sind, was Einfluss auf die Architektur des frühen Myokardiums nimmt. Effektoren des PCP Signalweges umfassen das Zytoskelett sowie Adhäsions- und Migrationsprozesse. In dieser Studie wird gezeigt, dass die Komponenten dieses Signalweges im Myokardium hauptsächlich Prozesse der Actomyosin Modulation regulieren und damit unter anderem die Morphologie der Kardiomyozyten beeinflussen. Zusätzlich ist die frühe Kardiogenese durch eine Relokalisierung der phosphorylierten Form der Myosin Regulatory Light Chain (MRLC) vom Kern zur Membran gekennzeichnet. Hier wird gezeigt, dass die Phosphorylierung von MRLC sowie die Relokalisation von den Kernkomponenten des PCP Signalweges kontrolliert werden sowie dass es im Verlauf der frühen Herzentwicklung u.a. durch die Relokalisierung von pMRLC zu Änderungen in der Gewebespannung kommt, welche sich auf die nukleäre Spannung auswirken und damit Veränderungen in der Genregulation hervorrufen. Diese Veränderungen werden hauptsächlich durch Effekte auf die Lokalisation und Aktivität des Serum Response Factors (SRF) vermittelt, welche in diesem Kontext durch die PCP Kernkomponente Pk1 reguliert sind.Formation of a complex multiple-chambered heart from the simple linear heart tube does not only require orchestrated morphogenesis of the myocardium, but also cardiac muscle differentiation and changes in intercellular electrical coupling. To date, the processes that lead to the formation of a functional syncytium are incompletely understood. One of the major pathways controlling multiple aspects of organogenesis and tissue morphogenesis is the planar cell polarity (PCP) pathway. Changes in tissue architecture are controlled by cell intercalation and collective cell migration. It is widely accepted that Wnt/PCP signaling plays a crucial role in guiding these cellular processes. This study provides evidence that morphogenesis of the heart is controlled by the non-canonical ligands Wnt11 and Wnt5b and the PCP core components Fzd7, Vangl2, Dvl2, and Pk1 through regulation of cell rearrangements during embryonic cardiac remodeling. Downstream effectors of the PCP pathway target adhesion processes, cytoskeleton, and migration. Here, it is revealed that PCP signaling in the heart affects cardiomyocyte morphology and actomyosin organization. Specifically, changes in the subcellular localization of the phosphorylated non-muscle myosin II regulatory light chain (pMRLC) at LHT stage are targeted by the PCP pathway core components. Furthermore, actomyosin relocalization concurs with changes in nuclear tension and SRF signal transduction within the myocardium. This study unravels a novel function of the PCP core component Pk1 in regulation of SRF translocation and target gene expression that is critical to cardiac maturation. Taken together, this study provides evidence that the PCP pathway is a major regulator of cardiac remodeling and organ maturation by modulating mechanosensitive SRF signal transduction involved in muscle differentiation.
23
AIMO, DARIA MARIANGELA. "Tra emozioni, affetti e sentimenti. Riflessioni e prospettive pedagogiche." Doctoral thesis, Università Cattolica del Sacro Cuore, 2007. http://hdl.handle.net/10280/139.
Full textAbstract:
Il presente lavoro di ricerca ha inteso porre le basi di una pedagogia del sentire umano.
Si è inteso indagare le emozioni gli affetti e i sentimenti da un punto di vista pedagogico-educativo. Muovendo dai contributi offerti dalla psicologia e dalle neuroscienze, dalla filosofia, dall'antropologia e dalla sociologia si è delineata una visione complessa e articolata dell'essenza, del valore e del significato del sentire umano.
Poiché nella riflessione pedagogica le emozioni, gli affetti e i sentimenti sono in misura variabile da sempre stati oggetto di attenzione, si è presentato, altresì, ripercorrendo e rileggendo criticamente, il pensiero di alcuni autori legati alla storia della pedagogia e alla pedagogia contemporanea. La scelta è avvenuta sulla scorta della significatività delle riflessioni circa la fondatività delle emozioni, affetti e sentimenti nella persona e nella relazione educativa; circa l'educazione del cuore nei percorsi di crescita e umanizzazione dell'educando.
Successivamente, nel riflettere sull'educabilità del sentire umano, si sono svolte precisazioni e chiarificazioni semantiche dei termini in questione e si è approfondito il tema della competenza emotivo-narrativa e della riflessività emotivo-affettiva.
Infine, prendendo le mosse da una micro ricerca svolta sull'affettività familiare si è tematizzata la famiglia come nucleo affettivo originario; il ruolo educativo gentioriale nella formazione emotivo-affettiva, il rapporto tra formazione emotivo-affettiva e formazione morale della persona.The present work of research meant to lay the bases of a pedagogy of human feeling. We intended to analyse the emotions, the affections and the feelings from a pedagogical and educational point of view. Beginning from literary contributions of the psychology and neuroscience, of the philosophy and anthropology and of the sociology, we delineated a complicated and well constructed vision about the essence, the value, and meaning of human sensibility and feeling. Because of in pedagogical consideration, emotions, affections and feelings, have always been object of attention in different ways, we have also critically showed the thought of some authors connected to the history of pedagogy and to the current pedagogy. It was due to the meaning of reflection about the importance of emotions, affections and feelings in the human being and in the educational relation; about the hart education in the growth of the child. After that, thinking about the education of human feeling, we realized semantic explanations regarding the terms of the phenomena of human feeling, we studied in depth the theme of emotional literacy and of the emotional reflectivity. At the end, starting from a micro research about family affectivity we talked about family as emotional and affective original nucleus; about the education parents role in the emotional growth; about the connection between emotional formation and the moral formation of the human being.
24
Bromley, Elizabeth Helen Claire. "Heat-induced structure formation by β-lactoglobulin." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596931.
Full textAbstract:
The heat-induced structure formation by the globular protein, b-lactoglobulin, has been studied over a wide range of solution conditions and heating regimes. The results are split into two main categories corresponding to the regimes in which b-lactoglobulin forms fine stranded and particulate gels. In the fine stranded regime (non-isoelectric pH), b-lactoglobulin was found to form highly ordered structures which bound the amyloid specific dyes Congo red and Thioflavin T. In the case of the pH 2.5 and no added NaCl, the X-ray fibre diffraction pattern was found to correspond well to that of amyloid. Higher order structures in the form of spherulites composed of assemblies of amyloid fibrils were also investigated. The kinetics of fibril formation in b-lactoglobulin was investigated and modelled using a theory based on a slow forwards reaction, generating an active species followed by a critical stable nucleus size dependent nucleation and growth. In the particulate regime (isoelectric pH), the gel structures were investigated using Environmental SEM, confocal microscopy and small angle X-ray scattering. The gels were found to comprise densely packed particles with fractal surfaces. The effects of ionic strength, pH, protein concentration and heating regime on the size of the particles were investigated. Increasing heating rate and holding temperature were found to decrease the particle size, with ionic strength increasing particle size. A peak in particle size was found as a function of pH as the isoelectric point was approached. These results were described in terms of two models. The first model, based on a temperature imposed equilibrium size, accounts well for the decrease in particle size with holding temperature. The second model based on a nucleation rate which is dependent on the temperature via the unfolding transition, was more successful at describing the heating rate dependence.
25
Lewis, Matthew Carrington. "Heat curing and delayed ettringite formation in concretes." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321775.
Full text
26
Tovey, Bethan. "Hearts and minds : the formation of identities in Anglo-Saxon literature." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.568079.
Full textAbstract:
This thesis aims to take a bottom-up approach to questions of Anglo-Saxon identity. Whereas recent studies have tended to begin with a concept such as Englishness or gender and used it as a glass through which to view Anglo-Saxon texts, I will instead begin by considering some of the basics of identity and considering how they may coalesce to construct more complex identities such as ethnicity. The first two chapters deal with the mind and intellect. They consider the bases of identity which may be found in the use of words, education and wisdom. Chapter one considers the processes of structuring identity through words, whether spoken or written. It focuses on the tensions between orality and literacy, considering the authority and status that each, in its different ways, may confer on individuals who use them well. Chapter two considers the role of communal wisdom and what it means to be wise. It asks whether wisdom is a type of identity in itself or something which is inherent in a range of different identities. Chapters three to six explore the physical aspects of identity. Chapter three identifies potential sources of conflict between secular culture and Christian ideas of bodily integrity, particularly in the area of sexuality. Chapter four examines the ways in which sexuality is subsumed in a concern with lineage, and goes on to consider the role of family in characterising an individual's reputation and virtue. Chapter five considers the results of physical impairment. Impairment is seen to be stylised and treated in a highly symbolic manner, becoming an outward sign of other kinds of identity, such as evil or holiness. Finally, chapter six considers the role of violence in constructing identity, examining the pain and suffering of saintly martyrs and the paradigms of heroism found in Beowulfand The Battle of Maldon. It asks whether it is possible for Christian and heroic identities to coexist in a single individual. The conclusion surveys the idea of "Englishness", seeking to show how this concept is informed by numerous other types of identity. It questions whether Englishness informs other types of behaviour, or is informed by them. It ends by advancing the idea that any study of Anglo-Saxon identity must take into account the multiplicity of identities available to individuals in the period.
27
Fernandez-Zelaia, Patxi. "Thermomechanical fatigue crack formation in nickel-base superalloys at notches." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48991.
Full textAbstract:
Hot sections of gas engine turbines require specialized materials to withstand extreme conditions present during engine operation. Nickel-base superalloys are typically used as blades and disks in the high pressure turbine section because they possess excellent fatigue strength, creep strength and corrosion resistance at elevated temperatures. Components undergo thermomechanical fatigue conditions as a result of transient engine operation. Sharp geometric features, such as cooling holes in blades or fir-tree connections in disks, act as local stress raisers. The material surrounding these features are potential sites of localized inelastic deformation and crack formation. To reduce customer costs associated with unnecessary overhauls or engine down-time, gas turbine manufacturers require accurate prediction methods to determine component endurances. The influence of stress concentration severity on thermomechanical fatigue crack formation is of particular importance as cracks often initiate in these hot spots. Circumferentially notched specimens were utilized to perform thermomechanical fatigue experiments on blade material CM247LC DS and disk material PM IN100. A parametric study on CM247LC DS was performed utilizing four notched specimens. Experimental results were coupled with finite element simulations utilizing continuum based constitutive models. The effects of applied boundary conditions on crack initiation life was studied in both alloys by performing experiments under remotely applied force and displacement boundary conditions. Finite element results were utilized to develop a life prediction method for notched components under thermomechanical fatigue conditions.
28
Malyk, Yu Yu. "Submicroscopic structure of myoendocardial formations of the left ventricle of the human’s heart." Thesis, БДМУ, 2021. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18437.
Full text
29
Chen, Qiang. "The major chloroplast low molecular weight heat shock protein." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185849.
Full textAbstract:
The goal of this dissertation is to provide information critical for understanding the function of the major chloroplast LMW HSP. The results of this research show that the production of a nuclear-encoded, chloroplast LMW HSP is a highly conserved event in the plant HS response, and that the HSP itself is highly homologous in divergent plant species. Three major conserved regions were identified in the chloroplast LMW HSP. The carboxyl-terminal HS domain of the chloroplast LMW HSP is also found in cytoplasmic LMW HSPs and identifies it as a member of the superfamily of eukaryotic LMW HSPs. The amino-terminal region is unique to the chloroplast LMW HSP and is capable of forming a Met-rich amphipathic α-helix. The chloroplast LMW HSP cannot be detected at normal growth temperatures, but accumulates dramatically in both leaves and roots during HS. The chloroplast LMW HSP is a stable protein with a half-life of approximately 52 h. In the chloroplast, the majority of PsHSP21 is localized in the soluble protein fraction. In its native state, PsHSP21 exists in a 200 kDa particle as is observed for cytoplasmic LMW HSPs. However, unlike the cytoplasmic LMW HSPs, the PsHSP21-containing particles do not aggregate into heat shock granules even under severe, abrupt HS conditions. The formation of the PsHPS21-containing particle can be replicated in isolated chloroplasts, but the chloroplasts must be from heat stressed plants. The protein sequence homology and the similar native structure of the LMW cytoplasmic and chloroplast HSPs suggests they perform similar functions in different cellular compartments. I propose that the 200 kDa particle is the functional form of PsHSP21. Furthermore, the chloroplast LMW HSP performs functions in all types of plastids similar to those of the cytoplasmic LMW HSPs, but with unique substrates within the special environment of plastids. This study provides the first information regarding the expression and structure of the chloroplast LMW HSP. Since the chloroplast contains only a single major LMW HSP, this study also provides the basis for developing a simple model system for studies of the function of all members of the ubiquitous LMW HSP family.
30
Carsbring, Amanda. "Heat Treatment and Secondary Phase Formation in FeCrNi Medium Entropy Alloys." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291251.
Full textAbstract:
The topics of high entropy alloys (HEA) and medium entropy alloys (MEA) have been heavily researched in recent years. A HEA usually consists of five or more base elements, and a MEA would have three or four base elements. These types of alloys are multi-principal element alloys (MPEA) that have been thought to have interesting properties due to their high configurational entropy, which was thought to be the reason for stabilized simple solid solution phase in the HEA. The high entropy effect contributing to stable single phase in these alloys has been discussed and has not been found to be a predicament to which MPEA that will present as single phase at lowered temperatures. Still, some of the HEA and MEA investigated have interesting properties such as high ductility and good thermal properties, as is the case for the commonly researched CoCrFeMnNi HEA and the CoCrNi MEA which are both solid solution FCC phase at lower temperatures. This master thesis aims to investigate one of the less commonly researched MEA: equimolar FeCrNi. This alloy has been studied previously, and it was found there might be a possibility of precipitation hardening the alloy. To further study this alloy system, three FeCrNi alloys in the close-to equimolar range were produced and underwent a series of aging heat treatments to study the amount of precipitated secondary phase with composition changes and different aging temperatures. The objective is to evaluate and interpret the data found in the different CALPHAD databases used in Thermo-Calc and FactSage software and make comparisons to the experimental results. This to discuss the possibilities of hardening this alloy through aging treatment. The alloys selected and produced are 33Fe33Cr33Ni, 40Fe30Cr30Ni and 45Fe30Cr25Ni, all in mol%. Through experimental investigation using x-ray diffraction (XRD) analysis, it is found that Cr-rich BCC phase is formed in all alloys after most of the aging treatments performed. The volume fraction of BCC was quantified through the reference intensity ratio (RIR) method. From quantification, the largest volume fraction BCC is found in the equimolar 33Fe33Cr33Ni alloy, and the lowest fraction BCC is shown in the 40Fe30Cr30Ni alloy. The increased volume fraction of BCC coincides with an elevated hardness in all three alloys. It is also found that out of the three equilibrium phase calculations used in this project, the ThermoCalc steel database TCHEA4 seems to give results that are in closest agreement with the experimental results. For future studies in this subject, the recommendation is to further study the mechanical properties of the FeCrNi MEA and assess possibilities for application.Högentropilegeringar och mediumentropilegeringar har studerats närmre de senaste åren på grund av deras intressanta mekaniska egenskaper. En högentropilegering består vanligtvis av fem eller flera baselement, och en mediumentropilegering har tre eller fyra baselement. Detta skiljer dem från konventionella legeringar som i regel har ett, maximalt två, baselement. Dessa typer av multi-baslegeringar har ansetts ha intressanta egenskaper på grund av deras höga konfigurationsentropi, vilken tros vara orsaken till stabilisering av fast lösningsfas i legeringarna. Högentropieffekten som bidrar till stabil enfas i dessa legeringar har diskuterats och har emellertid inte visat sig vara tillförlitligt för att förutsäga vilka multi-baslegeringar som blir fast lösningsfas vid ett lägre temperaturintervall. Ändå har några av de undersökta legeringarna intressanta egenskaper som hög duktilitet och goda termiska egenskaper, vilket är fallet för högentropilegeringen CoCrFeMnNi och mediumentropilegeringen CoCrNi som båda är enkel FCC-fas vid lägre temperaturer. Detta examensarbete syftar till att undersöka en av de mindre omnämnda mediumentropilegeringarna: ekvimolär FeCrNi. Denna legering har studerats tidigare, och det visade sig att det kan finnas en möjlighet att utskiljningshärda legeringen. För att ytterligare studera detta legeringssystem producerades tre FeCrNi-legeringar i ett sammansättningsintervall nära ekvimolär sammansättning, som sedan genomgick en serie åldringsbehandlingar för att studera mängden utskild sekundär fas beroende på sammansättning och åldringstemperatur. Målet är att utvärdera och tolka data som finns i de olika CALPHAD-databaserna som används i beräkningsverktygen Thermo-Calc och FactSage, och därefter göra jämförelser med experimentresultaten. Detta för att diskutera möjligheterna att härda dessa legeringar med partikelutskiljning. De legeringar som valts och tillverkats är 33Fe33Cr33Ni, 40Fe30Cr30Ni och 45Fe30Cr25Ni, alla angivna i molprocent. Genom experimentella undersökningar med röntgendiffraktionsanalys hittades att BCC-fas med höga halter Cr bildats i alla legeringar efter majoriteten av åldringsbehandlingarna som utförts. Volymfraktionen av BCC kvantifierades genom beräkningar från referensintensitetsförhållande (RIR). Från kvantifiering fås den största volymfraktionen BCC i den ekvimolära 33Fe33Cr33Ni-legeringen, och den lägsta fraktionen BCC i 40Fe30Cr30Ni-legeringen. Högre volymfraktion BCC sammanfaller med en förhöjd hårdhet i alla tre legeringarna. Det visar sig också att utav de tre jämviktsfasberäkningarna som används i detta projekt så är det ThermoCalc-ståldatabasen TCFE10 som gett resultat som överensstämmer med experimentresultaten. För framtida undersökningar inom detta område rekommenderas att studera de mekaniska egenskaperna hos FeCrNi och bedöma möjligheterna för tillämpning av materialet.
31
Williams, Timothy C. "Combustion, NOx formation and mixing processes in Helmholtz pulse combustors." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/18459.
Full textAbstract:
This thesis presents a laser diagnostic investigation into the combustion, NOx formation and mixing processes occurring within the optically assessed combustion chamber of a methane-fired (10kW), fully premixed, self-aspirating, Helmholtz pulse combustor. The inlet geometry of the combustion chamber consisted of a step expansion and a bluff body obstacle formed by a stagnation plate. The focus of the investigation was the effects of the stream-wise position of the stagnation plate on the pulse combustion processes. A comprehensive parametric study of the performance of the pulse combustor is presented with stagnation plate position, air/fuel ratio and tailpipe length as the variables. The operating frequency and peak pressure amplitude trends were found to vary in accordance with the Rayleigh criterion. The operation of the combustor was more stable with the effective heat-release point preceding the resonant acoustic peak. Operation outside of this regime produce increased levels of CO. Time-resolved, laser-sheet flow visualisation images are presented of the flow structures within the combustion chamber. The inlet mixing - between the reactants and residual gases - was dominated by the formation of two counter-rotating toroidal vortices. In general, the inlet mixing was found to decrease as the stagnation plate was moved further into the combustion chamber. However, other mechanisms that tended to counter this trend were observed. Under certain conditions, significant flow reversals were imaged with gases penetrating the combustion chamber from the tailpipe. The combustion event was investigated using cycle-resolved chemiluminescence and laser induced fluorescence imaging of OH* radicals. Ignition of the fresh reactants by residual combustion/radical activity was found to occur along the interface between reactants and residual gases. The increase in reaction zone area generated by the action of the toroidal vortices provided the necessary mechanism for the rapid combustion of the reactants. The reduced mixing associated with moving the stagnation plate further into the combustion chamber produced a more compact combustion zone with less interaction between combusting reactants and cooler residual gases. This modification to the combustion zone was consistent with the measured trends of rising NOx tailpipe emissions and decreasing N02/NOx ratio. Under certain conditions, a reversal in the NOx and N02/NO, ratio trends was observed. This was explained by an augmentation of heat transfer rate out of the combustion chamber, characterised by increased flow reversal strength, which lead to cooler residual gases. Additional mechanisms, which modified the inlet mixing process, were also identified as contributing to the reversal of the NOx trends.
32
Hu, Xiaogang. "A hydrological analysis of icing formation /." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=42054.
Full textAbstract:
Icings are common hydrological phenomena in arctic and subarctic regions. Their bodies are made up of the accumulation of ice layers formed by the freezing of overflow water during the winter season. Icing formation is a process involving a complex system of thermodynamics and hydrodynamics. In this thesis, the formation mechanics of river icings and ground icings are studied in terms of both thermal and hydrological processes.The energy exchange systems during icing layer formation involve two ice water interfaces and some intra-layer water flow. Using energy balance analysis, this research finds that the outgoing energy components can be ranked according to their importance, with sensible heat being the most important component, radiation heat loss being of secondary importance, and latent heat loss being the least important factor. Further, this research illustrates that the heat conduction between the underlying ice and a newly formed icing layer is time dependent. For example, during the first half cycle of icing layer formation, heat is conducted into the underlying ice, but during the second half of the cycle the heat is conducted in an opposite direction.
During icing layer formation, the energy input is supplied mainly by water and incoming solar radiation. Intra-layer running water provides a significant amount of energy when air temperatures are milder, but its significance decreases when air temperatures become colder. Solar radiation during the day may also play an important role in the energy supply regime.
River icing formation involves several hydrological processes. The location of a river icing is basically controlled by the channel slope. The damming effect of icing mass plays a significant role in the extension of the icing body, especially in the upstream direction. River icings grow slowly, and generally experience three stages of development, namely the 'freeze-up' stage, 'obstruction' stage and 'overflow' stage, the third stage dominating icing growth. The formation of each icing layer is virtually a small-scale reproduction of these three stages. The model simulation shows that the thickness of icing accumulation increases with an increase in the initial water depth in the channel, but simulation also shows that there is a limiting threshold. The thickness of icing accumulation decreases when the initial channel water depth exceeds this threshold.
The growth of an icing is an event-dominated discontinuous process. Even during one icing layer formation, simultaneous growth occurs only within a very limited distance. At a specific location, icing growth is related temporally only over a short period of time. As a discontinuous process, icing spreading and thickening during an overflow event depends entirely on the climatic and topographical conditions.
Even though icing layering is influenced by many variables, under small discharge rates, as in the case of ground icing growth, statistical analyses show that the mean spreading length of an overflow event can be described efficiently by five variables: discharge, the temperature of the water, the product of air temperature and wind speed, air temperature and the icing surface slope previous to overflow. The maximum spreading length, however, may only be controlled by four variables: discharge, water temperature, air temperature and the product of air temperature and wind speed. Under field conditions, when wind speed is not measured, this wind related variable may be dropped with only a small decrease in confidence level.
33
Scholey, Kenneth Erwin. "Heat tranfser and crack formation in water-cooled zinc fuming furnace jackets." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30078.
Full textAbstract:
In the zinc slag fuming process, zinc is extracted from lead blast furnace slag by reduction with a coal/air mixture injected into the slag through submerged tuyeres. The furnace is constructed of water-cooled jackets to contain the molten bath and freeze a protective slag layer. The slag layer greatly reduces vessel wear caused by the corrosive and violently agitated bath. However, the jackets are known to develop cracks in the working face panel that initiate on the slag face and propagate towards the water cavity. If the cracks reach the water cavity explosions may result should the molten slag come into contact with the water.
In this study an analysis of heat transfer in the jacket has been carried out using in-plant measurements and mathematical modelling. The working face of a water jacket was instrumented with thermocouples and positioned in a fuming furnace at the Trail smelter of Cominco Ltd. Measurements revealed the presence of large thermal transients or temperature "spikes" in the panel approximately 20 cm above the tuyeres. The transients were observed during charging and tapping of the furnace and are likely associated with slag fall-off due to surface wave action and gas injection effects when the bath level is low. Temperatures at the mid-thickness were seen to rise by as much as 180 °C above the steady-state level. Under these conditions large compressive stresses are produced in the panel that are sufficient to cause yielding. Over time, the transients lead to low-cycle fatigue of the working face panel with crack formation initiating at pre-existing surface flaws.
A mathematical modelling analysis of the transient freezing phenomena has been carried out using the finite element method. The results indicate that the temperature spikes are associated with the sudden removal of patches of slag and molten slag
coming into direct contact with the jacket. The temperature spikes are large enough to generate compressive stresses that cause yielding of the material in the exposed area. In order to reduce the damage caused by the removal of the slag shell an increased number of anchoring studs should be used in critical areas and a higher water circulation velocity should be employed to increase the size of the frozen slag layer and its strength.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
34
Scullin, Robert J. "Engaging hearts and minds Ignatian spirituality and students reflecting on service /." Online full text .pdf document, available to Fuller patrons only, 2000. http://www.tren.com.
Full text
35
Köll, Thomas. ""I Cannot Hear The Altos!" : An experiment on choir formations and spacing to improve the hearing within the choir in concert halls with dampened acoustics." Thesis, Kungl. Musikhögskolan, Institutionen för komposition, dirigering och musikteori, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kmh:diva-2138.
Full text
36
Amaro, Robert L. "Thermomechanical fatigue crack formation in a single crystal Ni-base superalloy." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/37172.
Full textAbstract:
This research establishes a physics-based life determination model for the second generation single crystal superalloy PWA 1484 experiencing out-of-phase thermomechanical fatigue (TMF). The life model was developed as a result of a combination of critical mechanical tests, dominant damage characterization and utilization of well-established literature. The resulting life model improves life prediction over currently employed methods and provides for extrapolation into yet unutilized operating regimes. Particularly, the proposed deformation model accounts for the materials' coupled fatigue-environment-microstructure response to TMF loading. Because the proposed model is be based upon the underlying deformation physics, the model is robust enough to be easily modified for other single crystal superalloys having similar microstructure. Future use of this model for turbine life estimation calculations would be based upon the actual deformation experienced by the turbine blade, thereby enabling turbine maintenance scheduling based upon on a "retirement for a cause" life management scheme rather than the currently employed "safe-life" calculations. This advancement has the ability to greatly reduce maintenance costs to the turbine end-user since turbine blades would be removed from service for practical and justifiable reasons. Additionally this work will enable a rethinking of the warranty period, thereby decreasing warranty related replacements. Finally, this research provides a more thorough understanding of the deformation mechanisms present in loading situations that combine fatigue-environment-microstructure effects.
37
Kho, Teresa Chea San. "Effect of flow distribution on scale formation in plate and frame heat exchangers." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/844239/.
Full textAbstract:
The uncertainty of fouling behaviour in plate heat exchangers is one of the main reasons (if not the main reason), why this heat exchanger type is not more widely installed in the chemical and process industry, despite the obvious potential for cost and energy savings. Recent investigations by Bansal (1994), have shown that similar heat exchanger plates with different corrugation patterns near the fluid inlet and outlet regions, fouled at very different rates under identical process conditions. As different corrugation patterns give rise to different flow patterns, the differences observed by Bansal (1994) are attributed to the effects of flow distribution on fouling rates in the plate channels. Consequently, in the present investigation, the effects of flow distribution on the precipitation fouling of calcium sulphate were studied experimentally using Alfa Laval P0l plates (diagonal flow), Alfa Laval M3 plates (diagonal and side flow), and 2-mm-thick stainless-steel flat plates (diagonal flow). Effects of solution flow velocity, temperature, concentration, port position, plate surface roughness and distributor design on fouling were investigated. For corrugated diagonal flow plates (P01 and M3), the fouling rate was found to increase with decreasing solution flow velocity, and increasing solution temperature and concentration. Not only is the initial solution concentration an important factor in the fouling process, but also the amount of solution concentration being topped up so as to maintain the initial concentration during a run, and the time of doing so, have been shown to have a dramatic effect on the fouling process. When compared with their side flow counterparts, diagonal flow plates exhibit slightly lower fouling resistance and pressure drop values. For the custom-made flat plates, increased fouling was observed with increasing solution concentration and plate surface roughness. In order to obtain a more even distribution of flow within the plate channel, low-flow-velocity and stagnant zones were avoided by using different distributor designs to channel fluid from the high- velocity regions to the low-velocity ones. In doing so however, all the 5 distributor designs examined created additional regions of low flow velocity in their wake. Visual observation of flow distribution and fouling deposition in corrugated and flat plate channels were performed using a corrugated and a flat transparent polycarbonate plate respectively. From these observations, it became obvious that the two conditions necessary for precipitation fouling of calcium sulphate to occur, are high temperature and low flow velocity. A few fouling mitigation methods were investigated. It was found that the addition of NaNO3 to calcium sulphate solution reduced CaSO4 fouling significantly. Velocity surges and the injection of air at a high flow rate for a short time period into the flowing solution, proved capable of removing an existing fouling layer. However, continuous air injection into the solution line, and the use of ion-sputtered plates and a magnetic device all failed to achieve any significant decrease in fouling. Different ways of incorporating excess heat transfer area in plate heat exchangers for fouling provision were evaluated. In the presence of adhesion-controlled fouling, the traditional method of adding extra parallel plates proved to be inferior when compared with the incorporation of larger plates with different aspect ratios and additional plates in a second pass. On the other hand, if no flow control is possible, a two pass arrangement and plates with half the standard plate width should be avoided for reaction fouling. Flow simulations were performed using the commercial Computational Fluid Dynamics (CFD) package, CFX. A flow passing through a 2-D channel with a single corrugation, and with multiple corrugations, has been modelled and interesting results have been obtained. Special emphasis was placed on the local flow distribution in a plate channel. This information was essential to improve the design of heat exchanger plates to guarantee longer operational cycles. Simulations were performed for different distributor designs and different plate shapes. Computational results compared well with those obtained experimentally.
38
Yun, Xiao. "The formation of ice by coupled heat and mass transfer within subcooled aqueous media." Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.723468.
Full text
39
Lu, Hui-Ming. "Analysis of Heat Flow and Residual Stress Formation during Hot Plate Welding of Plycarbonate." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392379062.
Full text
40
Lu, Hui-Ming. "Analysis of heat transfer and residual stress formation during hot plate welding of polycarbonate /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487945744572453.
Full text
41
Macia, Mario Luis. "A study of dendritic precipitation, grain boundary serration formation and discontinuous precipitation in nickel base superalloys." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/19645.
Full text
42
Krishna, Kiran. "Measurement and prediction of aerosol formation for thesafe utilization of industrial fuids." Texas A&M University, 2003. http://hdl.handle.net/1969.1/306.
Full textAbstract:
Mist or aerosol explosions present a serious hazard to process industries. Heat transfer fluids are widely used in the chemical process industry, are flammable above their flash points, and can cause aerosol explosions. Though the possibility of aerosol explosions has been widely documented, knowledge about their explosive potential is limited. Studying the formation of such aerosols by emulating leaks in process equipment will help define a source term for aerosol dispersions and aid in characterizing their explosion hazards.
Analysis of the problem of aerosol explosions reveals three major steps: source term calculations, dispersion modeling, and explosion analysis. The explosion analysis, consisting of ignition and combustion, is largely affected by the droplet size distribution of the dispersed aerosol. The droplet size distribution of the dispersed aerosol is a function of the droplet size distribution of the aerosol formed from the leak. Existing methods of dealing with the problem of aerosol explosions are limited to enhancing the dispersion to prevent flammable concentrations and use of explosion suppression mechanisms. Insufficient data and theory on the flammability limits of aerosols renders such method speculative at best. Preventing the formation of aerosol upon leaking will provide an inherently safer solution to the problem.
The research involves the non-intrusive measurement of heat transfer fluid aerosol sprays using a Malvern Diffraction Particle Analyzer. The aerosol is generated by plain orifice atomization to simulate the formation and dispersion of heat transfer fluid aerosols through leaks in process equipment. Predictive correlations relating aerosol droplet sizes to bulk liquid pressures, temperatures, thermal and fluid properties, leak sizes, and ambient conditions are presented. These correlations will be used to predict the conditions under which leaks will result in the formation of aerosols and will ultimately help in estimating the explosion hazards of heat transfer fluid aerosols. Heat transfer fluid selection can be based on liquids that are less likely to form aerosols. Design criteria also can incorporate the data to arrive at operating conditions that are less likely to produce aerosols. The goal is to provide information that will reduce the hazards of aerosol explosions thereby improving safety in process industries.
43
Kwon, Daniel W. 1980. "Cryogenic heat pipe for cooling high temperature superconductors with application to Electromagnetic Formation Flight Satellites." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/62966.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 195-200).
An emerging method of propellant-less formation flight propulsion is the use of electromagnets coupled with reaction wheels. This technique is called Electromagnetic Formation Flight (EMFF). In order to create a large magnetic field necessary for actuating formation flying spacecraft, EMFF uses high temperature superconducting (HTS) wire since it is able to carry a large current at low power. To achieve superconductivity, the HTS wire needs a cryogenic thermal control system to maintain the wire temperature below the critical temperature and this temperature must be maintained over the entire EMFF coil, which could be as large as two meters in diameter. For commercially available HTS wire, this critical temperature is 110 K. Since EMFF obviates the need for consumables for formation flying maneuvers, the thermal system must also be consumable-free. The research in this thesis investigates a consumable-free method of maintaining isothermalization for a large scale HTS coil. The HTS coil resides inside a thermally conductive jacket which is used for isothermalization. A cryocooler is attached to the thermally conductive jacket and is used for heat extraction. Wrapped around the thermally conductive jacket is multilayer insulation which is used to reduce the heat load into the HTS coil. This thermal system has the ability to maintain constant temperature in the presence of a rapidly changing thermal environment, such as low Earth orbit. Both a solid conductor and a heat pipe were investigated for use as the thermally conductive jacket. Finite difference models were developed to model a single coil in space and a coil inside a vacuum chamber. In addition, the research in this thesis investigates the design, operation, and testing of a cryogenic heat pipe. The heat pipe uses nitrogen as a working fluid and a stainless steel mesh as the wicking structure. As a proof of concept, an 86 cm long heat pipe was constructed as the thermally conductive jacket enclosing the HTS wire. The working fluid, at saturation condition, maintains a constant temperature below the HTS wire critical temperature. Testing of the heat pipe in a vacuum chamber was conducted to verify the power capacity of the heat pipe. Verifying the proof of concept cryogenic heat pipe led to construction of a full scale circular heat pipe for testing in a two meter diameter toroidal vacuum chamber. This system also achieved saturation condition and showed the potential for HTS cooling. The experiments in this thesis demonstrate the feasibility of operating large HTS coils for future formation flying missions.
by Daniel W. Kwon.
Ph.D.
44
Gustafsson, Ann-Sofie. "Radiation response in human cells : DNA damage formation, repair and signaling." Doctoral thesis, Uppsala universitet, Medicinsk strålningsvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-265137.
Full textAbstract:
Ionizing radiation induces a range of different DNA lesions. In terms of mutation frequency and mammalian cell survival, the most critical of these lesions is the DNA double-strand break (DSB). DSB left unrepaired or mis-repaired may result in chromosomal aberrations that can lead to permanent genetic changes or cell death. The complexity of the DNA damage and the capacity to repair the DSB will determine the fate of the cell. This thesis focuses on the DNA damage formation, repair and signaling after irradiation of human cells. Radiation with high linear energy transfer (LET) produces clustered damaged sites in the DNA that are difficult for the cell to repair. Within these clustered sites, non-DSB lesions are formed that can be converted into a DSB and add to the damage complexity and affect DSB repair and the measurement. Heat-labile sites in DNA are converted into DSB at elevated temperatures. We show that heat-released DSB are formed post-irradiation with high-LET ions and increase the initial yield of DSB by 30%-40%, which is similar to yields induced by low-LET radiation. DNA-PKcs, a central player in non-homologous end-joining (NHEJ), the major mammalian DSB repair pathway, has been found to be both up- and downregulated in different tumor types. In Paper II we show that low levels of DNA-PKcs lead to extreme radiosensitivity but, surprisingly, had no effect on the DSB repair. However, the fraction of cells in G2/M phase increased two-fold in cells with low levels of DNA-PKcs. The study continued in Paper IV, where cells were synchronized to unmask potential roles of DNA-PKcs in specific cell cycle phases. Irradiation of DNA-PKcs suppressed cells in the G1/S phase caused a delay in cell cycle progression and an increase in accumulation of G2 cells. Further, these cells showed defects in DNA repair, where a significant amount of 53BP1 foci remained after 72 h. This further strengthens the hypothesis that DNA-PKcs has a role in regulation of mitotic progression. Several cellular signaling pathways are initiated in response to radiation. One of these downstream signaling proteins is AKT. We identified an interaction between DNA-PKcs and AKT. Knockouts of both AKT1 and AKT2 impaired DSB rejoining after radiation and low levels of DNA-PKcs increased radiosensitivity and decreased DNA repair further.
45
Tinoco, José. "On the Spray Forming of Metals, the Formation of Porosity and the Heat Evolution during Solidification." Doctoral thesis, KTH, Casting of Metals, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3636.
Full textAbstract:
This thesis deals with the heat evolution duringsolidification and its relation to the formation of porosity.It intends to improve the current understanding of theformation of porosity in cast materials with special interestin nodular cast iron and the spray forming process. Twodifferent systems, a Fe-based alloy, Cast iron, and a Ni-basedalloy, Inconel 625, are examined. The effect on the heatevolution of the morphology and the processing parameters inspray forming are treated.
An evaluation of the microstructural features, segregationbehavior and physical properties such as latent heat of fusionis performed byusing thermal analysis under cooling ratesranging from 0.1 to 104 K/s. In order to achieve this amodified differential thermal analysis (DTA) equipment, amirror furnace and levitation casting are used. Results arepresented in terms of the fraction of solidified, the coolingrate and the microstructure observed. The measured latent heatof fusion is not constant throughout the solidificationprocess. Variations in morphology and cooling rate affect therelease of the latent heat.
A thermodynamic model is used to describe the experimentalobservations and to explain the formation of pores in nodularcast iron by taking into consideration the formation of latticedefects during the liquid/solid transformation. In this casethe formation of porosity is regarded as a consequence ofchanges in the volume fraction ratio graphite/ during thesolidification process.
A numerical model of the spray forming process is developedby means of CFD modelling and compared with experimentalmeasurements performed in an industrial facility. Stagnationpressure measurements provided information about the gas flowvelocity and an analysis of the overspray powder providedinformation about the particle thermal history. Evaluation ofthe deposit was also performed. It is observed that the processconditions in spray forming promote non-equilibriumsolidification even though solidification at the deposit occursat a lower rate. In this case the porosity formed near theinterface substrate/deposit depends largely on the substratetemperature. The presence of certain reactive elements, such astitanium, affects the porosity levels in the rest of thedeposit.
Keywords:Thermal Analysis, Nodular Cast Iron, Inconel625, CFD, Flow Assesment, Multiphase Flow, Spray Deposition,Microporosity, Superalloys
46
Miller, Helen. "The effect of heat on graft union formation in dormant Sitka spruce (Picea sitchensis (Bong.) Carr.)." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306468.
Full text
47
Simmonds, Scott. "Formation and avoidance of surface defects during casting and heat-treatment of single-crystal nickel-based superalloys." Thesis, University of Leicester, 2014. http://hdl.handle.net/2381/28806.
Full textAbstract:
Nickel-based superalloys are a class of materials that have been specifically developed for high temperature applications for use in aero-engines and power generation. The evolution of superalloy chemistry and solidification structure has made the control and prevention of defect formation in single-crystal components increasingly challenging. This study examines the formation and avoidance of Surface Scale and Surface Melting, both of which are detrimental to the production cost and the performance of single-crystal turbine components. Surface Scale is a defect found on the surface of as-cast single-crystal components identified as a region of discolouration. A systematic analysis reveals that Surface Scale forms in the solid-state during casting due to the combined effects of (1) differential thermal contractions between mould and metal and (2) transient oxidation of the exposed metal casting surface at temperature below ~1300°C. The resultant transient oxide film is 0.5-1μm thick whilst the remaining surface undergoes a mould-metal reaction during the initial stages of casting, at temperatures above the liquidus, producing a 1-2μm thick protective layer of Al[subscript 2]O[subscript 3]. Surface Melting is identified on the heat-treated blade surface as an area of localised melting within the Scaled surface area. Through an in-depth analysis of the microstructural evolution it was found that Surface Melting is a consequence of elemental evaporation of γ-phase stabilisers. The subsequent change in chemistry results in the transformation of the γ phase to γ’ and TCPs and a concomitant occurrence of incipient melting at the surface during solution heat treatment. This thesis concludes that the prevention of Surface Scale is made possible by the use of an inert atmospheric gas, such as Argon, within the casting furnace. However, the subsequent formation of Surface Melting during heat-treatment can only be prevented by pre-oxidising the as-cast components, thus forming Al[subscript 2]O[subscript 3] in order to form a protective barrier to evaporation.
48
Uenishi, Keisuke. "Formation of Non-equilibrium Phases in the Alloy Systems with Positive Heat of Mixing by Mechanical Alloying." Kyoto University, 1992. http://hdl.handle.net/2433/74609.
Full text
49
Hatherley, Rowan. "In silico characterisation of the four canonical plasmodium falciparum 70 kDa heat shock proteins." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1004086.
Full textAbstract:
The 70 kDa heat shock proteins expressed by Plasmodium falciparum (PfHsp70s) are believed to be essential to both the survival and virulence of the malaria parasite. A total of six Hsp70 genes have been identified in the genome of P. falciparum. However, only four of these encode canonical Hsp70s, which are believed to localise predominantly in the cytosol (PfHsp70-1 and PfHsp70-x), the endoplasmic reticulum (PfHsp70-2) and mitochondria (PfHsp70-3) of the parasite. These proteins bind and release peptide substrates in an ATP-dependent manner, with the aid of a J-domain protein cochaperone and a nucleotide exchange factor (NEF). The aim of this study was to identify the residues involved in the interaction of these PfHsp70s with their peptide substrates, their J-domain cochaperones and potential NEFs. These residues were then mapped to three-dimensional (3D) structures of the proteins, modelled in three different conformations; each representing a different stage in the ATPase cycle. Additionally, these proteins were compared to different types of Hsp70s from a variety of different organisms and sequence features found to be specific to each PfHsp70 were mapped to their 3D structures. Finally, a novel modelling method was suggested, in which the structures of templates were remodelled to improve their quality before they were used in the homology modelling process. Based on the analysis of residues involved in interactions with other proteins, it was revealed that each PfHsp70 displayed features that were specific to its cellular localisation and each type of Hsp70 was predicted to interact with a different set of NEFs. The study of conserved features in each PfHsp70 revealed that PfHsp70-x displayed various sequence features atypical of both Plasmodium cytosolic Hsp70s and cytosolic Hsp70s in general. Additionally, residues conserved specifically in Hsp70s of Apicomplexa, Plasmodium and P. falciparum were identified and mapped to the each PfHsp70 model. Although these residues were too numerous to reveal any information of specific value, these models may be useful for the purposes of aiding the design of drug compounds against each PfHsp70. Finally, the novel modelling approach did show some promise. Half of the models produced using the modified templates were of a higher quality than their counterparts modelled using the original templates. This approach does still require a lot of validation work and statistical evaluation. It is hoped that it could prove to be a useful approach to homology modelling when the only templates available are poor quality structures.
50
Hughes, Robert T. "NOx FORMATION IN LIGHT-HYDROCARBON, PREMIXED FLAMES." UKnowledge, 2018. https://uknowledge.uky.edu/me_etds/118.
Full textAbstract:
This study explores the reactions and related species of NOx pollutants in methane flames in order to understand their production and consumption during the combustion process. To do this, several analytical simulations were run to explore the behavior of nitrogen species in the pre-flame, post- flame, and reaction layer regions. The results were then analyzed in order to identify all "steady-state" species in the flame as well as the determine all the unnecessary reactions and species that are not required to meet a defined accuracy. The reductions were then applied and proven to be viable.