Dissertations / Theses on the topic 'Tie2'
To see the other types of publications on this topic, follow the link: Tie2.
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 'Tie2.'
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
Seegar, Tom CM. "TIED TOGETHER: A MOLECULAR ROLE FOR TIE1 IN ANGIOPOIETIN TIE2 SIGNALING." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2122.
Full textAbstract:
The primary function of the vascular system is the maintenance of oxygen homeostasis for all metazoan tissue. Angiogenesis, the remodeling and maintenance of new blood vessels from an existing vessel, is primarily controlled through the endothelial specific receptor tyrosine kinase Tie2, and the orphan receptor tyrosine kinase, Tie1. Although these receptors share highly conserved, genetic and biochemical analysis has shown these receptors have distinct and essential roles in angiogenesis. Tie2 activation typically results in vessel stability and quiescences and has further been shown to interact with all four sub-types of the angiopoietin signaling factors, Ang1-4. Conversely, Tie1 is involved in vascular remodeling and has no known ligands. The aim of this study is to resolve the molecular mechanism in which Tie1 modulates Angiopoietin-induced Tie2 signaling. Using biophysical, structural, and biochemical assays we show Tie1 directly interacts with Tie2 via electrostatic interactions housed within the extracellular domains. The binding of Tie1 to Tie2 attenuates Tie2 phosphorylation. We further show the constitutive agonist of Tie2, Ang-1, is capable of excluding Tie1 initiating Tie2 activation. Whereas the antagonist, Ang-2, is in incapable of excluding Tie1. Finally, we identify a region within the angiopoietin receptor-binding domain that is capable of including or excluding Tie1 from Tie2. Based upon the available data, we provide a model for Angiopoietin-induced Tie2 signaling.
2
Dalton, Annamarie. "Regulation of Tie2 Extracellular Complex Formation in Angiogenesis." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3780.
Full textAbstract:
Pathological angiogenesis is an essential component of tumor growth, development, and metastasis for which few effective therapeutic options exist. Though many cancer therapies target the function of cell surface receptors, mechanisms regulating membrane receptor crosstalk remain unclear. Two important families of receptors in angiogenesis, the Ties and Integrins, respond to the extracellular environment via outside-in and, in the case of Integrins, also inside- out signaling. Recent reports showed that the endothelial specific tyrosine kinase receptor, Tie2, forms complexes with two of the endothelial Integrin heterodimers, α5β1 and αVβ3, providing a convenient mechanism for the integration of extracellular stimuli. Our data confirm the interaction between Integrins and Tie2 and additionally indicate an interaction with the orphan co-receptor Tie1. To elucidate the biological role of these macromolecular complexes, biochemical and biophysical methods including co-immunoprecipitation, FRET microscopy, and cellular based assays were used to follow receptor/Integrin association in response to the Tie2 ligands Angiopoietin-1 and -2 as well as the Integrin ligand fibronectin. Furthermore, structural analysis by small angle x-ray scattering of Tie2-ligand complexes and specific Integrin and Tie complexes are being used to identify the basis for growth factor receptor and Integrin signal transduction.
3
Forget, Mary A. "Tumor Angiogenesis is all Tied up in Tie2-Expressing Macrophages." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1356032077.
Full text
4
Nyamay'Antu, Alengo. "Elucidating the mechanism of angiopoeitin-mediated Tie2 signalling." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/elucidating-the-mechanism-of-angiopoeitinmediated-tie2-signalling(4269f3c3-fc71-455d-ae5b-4bc47dda78ca).html.
Full textAbstract:
Research on angiogenesis has been focused on developing anti-angiogenic therapies to target endothelial cell-specific signalling pathways, as a mean to limit tumour outgrowth and metastasis. One of the main targets is the endothelial cell-specific Tie2 receptor and its ligands, the angiopoietins, which controls the later stages of angiogenesis. Although the angiopoietin/Tie2 signalling pathways have been well characterized, the molecular mechanism by which the ligands regulate Tie2 activity remains unclear. To address this question, we determined whether the activation mechanism of Tie2 is induced by dimerisation alone, or whether subsequent relative rotation of the kinase domain is required. Here we employed a coiled-coiled based protein engineering approach to identify the relative orientations of the kinase domains that are optimal for Tie2 activation. By replacing the extracellular domain of Tie2 with the dimeric parallel coiled-coil motif Put3cc, we generated ligand-independent homodimers of the kinase domains Put3cc-Tie2 I-VII that have distinct orientations. We show that dimerisation is sufficient to induce Tie2 activation and downstream activation of Akt, and that varying the interface of the kinase domain in Tie2 dimers can increase its catalytic efficiency. In addition we examined for the presence of potential dimerisation within the transmembrane and intracellular domain of Tie2. We show that the KD and potentially the TM contain dimerisation motifs that stabilise Tie2 in the inactive and active conformations. In addition, we show that deletion of the potential coiled-coil motif in the JM does not disrupt dimerisation but decreases the catalytic efficiency of Tie2. Finally, we propose that the activation mechanism of Tie2 may be similar to the previously described asymmetric dimer formation of EGFR and FGFR receptors.
5
Park, Eun-Hee 1971. "Mechanisms of translation initiation of receptor tyrosine kinase Tie2." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102690.
Full textAbstract:
Angiogenesis is a process of new blood vessel formation and is the culmination of both mitogenic and tissue remodeling events, resulting in neovascularization. It is a physiological process that is required for, amongst others, normal embryonic development, female reproductive function, and wound healing. Angiogenesis is a tightly regulated process which is balanced by both positive and negative factors. However, in many disease states, including diabetic retinopathy, age-related macular degeneration, rheumatoid arthritis, and several cancers, dysregulation of angiogenesis contributes to disease progression. Previous published reports have implicated the coordinated activities of at least two families of receptor tyrosine kinases (RTKs), the vascular endothelial growth factor receptor (VEGFR) and the Tie receptor families, in this process.Tie2, an endothelial-specific receptor tyrosine kinase, plays an essential role in normal blood vessel maturation, remodeling, and stability. Tie2 expression is also upregulated in various cancers indicating a role in tumor angiogenesis. The human Tie2 mRNA transcript contains an unusually long (372 nucleotides) 5' untranslated region (UTR) with five upstream open reading frames (uORFs). In this thesis, we demonstrate that the Tie2 5' UTR promotes cap-independent translation, indicating the presence of functional internal ribosome entry site (IRES). In addition, we illustrate that Tie2 IRES activity is maintained, and even slightly stimulated, under hypoxic conditions when cap-dependent protein synthesis is attenuated. We further show that the Tie2 IRES is functional during quiescence, another condition known to compromise cap-dependent translation. These results present how Tie2 mRNA is translated despite a cumbersome structured 5' UTR and how its production is secured under unfavorable environmental conditions.
We define experimental conditions where the Tie2 IRES is not active, allowing us to assess the contribution of cap-dependent translation to Tie2 protein synthesis. We demonstrate evidence that Tie2 mRNA can be translated via both cap-dependent scanning mechanism and internal initiation. Moreover, we show that the presence of the uORFs within the 5' UTR is inhibitory to downstream translation initiation. Our results suggest that the uORFs serve to decrease the proportion of ribosomes competent for reinitiation as they traverse the mRNA 5' UTR and thus minimizing interference with the IRES and/or mediating inefficient translation of the potent protein under normal conditions. Like many other cellular IRESes, the entire Tie2 5' UTR appears to be required for maximum IRES activity.
Taken together, our results underscore the complex mechanisms to control gene expression at the level of translation initiation of the Tie2 mRNA.
6
Muhammad, Sharif Ossai. "Characterizing the interaction between VE-PTP, Tie2 and VE-Cadherin." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2869.
Full textAbstract:
Many signaling pathways have been shown to be involved in the formation of the vascular system. Among them are the endothelial specific receptor families such as VEGF, Ang/Tie, as well as other signaling pathways such as semaphorins, which are also involved, in axonal guidance. It is known that the interaction between receptor tyrosine kinase, Tie2, VE-Cadherin, and VE-PTP mediate endothelial cell quiescence and adhesion. However, the structural basis of these interactions is not well understood. The aim of our study is to characterize the binding interactions between these players. Another important part of our study is describing the cross-talk between vasculature and nervous system by characterizing the Neuropilin/Plexin/Semaphorin system. VE-Cadherin along with neuropilins plays an essential role by directing VEGF signals to the appropriate location and coordinating the activation of downstream molecules. We characterize the interaction between Tie2, VE-PTP and VE-Cadherin by (FRET)-based proximity assay, fluorescence lifetime imaging, and co-immunoprecipitation assays. Our data showed a consistent localization of the protein and FRET signal for Tie2 and VE-PTP prior to ligand recognition. We showed the association between Tie2 and VE-Cadherin complex by co-immunoprecipatation. However, our FRET data was not consistent. The examination of VE-PTP and VE-Cadherin for association and localization of the protein showed a very unique, mutually exclusive localization of the protein. Our study of Neuropilin/Plexin/Semaphorin system showed changes in the protein localization, FRET signal and morphology upon stimulation of HEK293 cells expressing Nrp/plexin with Sema3D. In this system VE-Cadherin along with neuropilins plays an essential role by directing VEGF signals to the appropriate location and coordinating the activation of downstream molecules. The characterization of extracellular binding between Tie2, VE-PTP, and VE-Cadherin, will help to better understand the molecular mechanisms of normal and tumor angiogenesis to develop new anti-angiogeneic therapies.
7
Tamagno, Sara. "Characterization of the role of angiopoietin-tie signalling in haematopoietic stem cell development in the murine embryo." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31056.
Full textAbstract:
Haematopoietic stem cells (HSCs) are capable of self-renewing and multi-lineage reconstitution of the haematopoietic system of irradiated recipient mice. In the mouse embryo, HSCs originate in a step-wise manner from the haematogenic endothelium. The first HSC precursor has been detected at E9.5 in the dorsal aorta, while HSCs emerge in the aorta-gonad-mesonephros (AGM) region around E11. To date, the molecular mechanisms regulating these events are poorly characterized. Through the activating role of Angiopoietin1 (Ang1) on Tie2 receptor, the Ang-Tie signalling pathway plays a critical role in HSC maintenance in the adult bone marrow niche. Tie2 ligand Angiopoietin2 (Ang2) is described as being a Tie2 inhibitor, however its role is unknown. The aim of this thesis was to characterise the role of Ang-Tie signalling pathway in HSC formation in the mouse embryo. First, I used an ex vivo aggregate system to culture with angiopoietins cells derived from the AGM region at stages of development preceding HSC formation (E9.5-E11). Ang2- treated cells were able to reconstitute the peripheral blood of recipient mice to a higher extent compared to control, indicating a role for Ang2 in promoting HSC maturation. Then, I characterized the expression pattern of Ang-Tie molecules in the AGM region. Ang2-expressing cells were identified as perivascular and sub-aortic mesenchymal cells located in the ventral side of the aorta and in proximity of intra-aortic haematopoietic clusters. Finally, I performed an RNA-seq analysis with the aim of unravelling the molecular mechanisms involved in Ang2-mediated HSC maturation. Pre-HSC-I were cultured in presence or absence of Ang2 and their transcriptional profiles were compared, revealing a number of genes and pathways up-regulated or down-regulated in presence of Ang2, which might indicate a role for Ang2 in increasing cell proliferation, favouring cell migration, and regulation of other signalling pathways involved in HSC development. All together, these data support Ang2 as a novel regulator for HSC formation.
8
Pucci, Ferdinando. "Gene expression signature and pro-angiogenic function of Tie2-expressing macrophages." Thesis, Open University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527443.
Full text
9
Dunmore, Benjamin John. "Investigations into the involvement of Tie2 in endothelial-mural cell interactions." Thesis, University of Leicester, 2004. http://hdl.handle.net/2381/27747.
Full textAbstract:
The interaction of endothelial cells and mural cells play a critical role in the stabilisation and maturation of the embryonic and postnatal vasculature. Several pathological situations exhibit poor and abnormal endothelial and mural cell association. In this study immunohistochemical analysis revealed dysmorphogenic microvessels within atherosclerotic plaques are lacking mural cells. Similar dysmorphogenic mural cell poor vessels were also observed in human myocardium following laser induced myocardial injury. In both cases elevated VEGF was detected associated with the mural cell poor vessels. To gain insight into the mechanisms controlling mural cell recruitment assays were established to examine directly smooth muscle cell migration and adhesion between smooth muscle cells and endothelial cells in culture. These assays were used to study the involvement of the angiopoietin/Tie2 system in recruitment and retention of mural cells. Ang-l was observed to stimulate endothelial-directed migration of putative mural cell precursors. The ligand also increased adhesion between endothelial cells and smooth muscle cells. To investigate further the possible role of Tie2 in interaction between endothelial cells and mural cells a mutant form of the receptor found in inherited venous malformations (VM) was studied. The form of VM associated with this mutant receptor is characterised by dysmorphogenic, enlarged mural cell vessels. Surprisingly, mutant Tie2 did not inhibit endothelial-induced mural cell migration or adhesion between endothelial cells and mural cells. Taken together these data suggest Tie2 has a role in regulating endothelial:mural cell interaction. Furthermore, the presence of mural cell poor vessels in the atherosclerotic plaque, injured myocardium and inherited VM may reflect escape of these vessels from regression by the presence of survival factors in the case of the plaque and injured myocardium, or constitutive anti-apoptotic signalling from mutant Tie2 in the case of VM.
10
Girlalt-Pujol, Marta. "Investigating the regulation of the endocytosis of tyrosine kinase receptor Tie2." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18527/.
Full textAbstract:
Tie2 receptor is a cell surface tyrosine kinase receptor expressed almost exclusively in endothelial cells, where it is mainly studied for its role in angiogenesis. Indeed, Tie2 has been related to various pathologies with vascular implication such as pulmonary hypertension, diabetes retinopathy and tumour growth. The regulation of Tie2 activation and function is complex, involving multiple factors that are still being investigated. For instance, after activation by the agonistic ligand Angiopoietin-1 (Ang1), Tie2 is internalized in cells by an endocytic mechanism that has yet to be fully characterised. As it has been shown that endocytosis of molecules can play a regulatory role in intracellular signalling in various ways I believe that the endocytosis of Tie2 may also be important in the regulation of its activity and cellular output. Therefore, I decided to characterise the endocytic mechanisms involved in the internalization of Tie2 to determine whether endocytosis can be a regulator of Tie2 signalling. To facilitate the study of Tie2 I created a HeLa cell line with inducible expression of a Tie2FLAG receptor that emulates both expression levels and characteristics of endogenous Tie2 in Human Umbilical Vein Endothelial Cells. To study the endocytosis of Tie2 receptor I developed an immunofluorescence-based assay to quantify the amount of internalized agonistic ligand Ang1 in a high throughput Screening format. I also performed complementary immunofluorescence and western blot analysis to investigate the characteristics of Tie2 internalization.
11
Yuth, Kenneth. "Characterizing the Phosphorylation State of Tie2 using SH2 Domain Fusion Proteins." VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/275.
Full textAbstract:
The cardiovascular system develops through two distinct processes in embryogenesis: vasculogenesis, whereby the primary plexus in the heart is formed along with embryonic and extraembryonic vasculature, and angiogenesis, which begins after vasculogenesis and results in the refinement and maturation of the branched vessel system. In pathological angiogenesis, tumors expand by releasing pro-angiogenic factors in response to hypoxic conditions. The Tie receptors, Tie1 and Tie2, are receptor tyrosine kinases that are integral to angiogenic pathways. A family of Angiopoietins, Ang1-4, have been shown to act as ligands for Tie2, of which Ang1 and Ang2 are best characterized. Activation of the receptor causes dimerization and autophosphorylation, whereby adaptor proteins recognizing the phosphorylated tyrosine activate downstream signaling via their Src homology 2 (SH2) domains. Currently there are no phosphospecific antibodies for Tie2, therefore, identifying critical residues responsible for certain pathways remains difficult. In our study, we aim to use purified SH2 domains of known binding partners to Tie2 to assess the phosphorylation state of the receptor under various cellular conditions and settings, utilizing immunoprecipitation and western blotting. Unexpectedly, we found that Tie2 can bind non-specifically to nickel sepharose when the SH2 proteins were used as antibody mimetics, and was unable to be consistently precipitated in Protein A sepharose when used in conjunction with a monoclonal YFP antibody. Under the latter conditions however we were able to precipitate the SH2 protein itself. When immunoprecipitations were used with cobalt activated IMAC beads, we were able to precipitate Tie2 in overexpressed systems using the SH2 domains of Shp2 N-C and Grb2. As expected, phosphorylation of Tie2 in the presence of its orphan receptor Tie1 was attenuated compared to wild-type levels. Based upon available data, we anticipate this method as a useful tool to assess the phosphorylation state of Tie2 and its signaling pathways in the near future.
12
Nätynki, M. (Marjut). "Venous malformation causative mutations affect TIE2 receptor trafficking, downstream signaling and vascular endothelial cell functions." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526211398.
Full textAbstract:
Abstract Venous malformations (VMs) are localized defects in vascular morphogenesis which can seriously impede or even threaten the patient’s life. VMs are characterized by enlarged, torturous vein-like channels lined by unevenly distributed smooth muscle cells. A large number of mutations in the endothelial TIE2 receptor tyrosine kinase have been found from more than half of the lesions screened, thus providing a common genetic cause. TIE2 has a crucial role in vascular development, remodeling and quiescence. However, the molecular and cellular abnormalities caused by TIE2-mutations in endothelial cells and how they relate to VM formation have been unknown. The aim of this study was to examine how VM-specific mutations affect the molecular characteristics of TIE2-receptor downstream signaling and cellular functions. Because no effective treatment has been available for VMs, a better understanding of the molecular basis of their pathology should enable the development of more potent and non-invasive treatments as well as provide a better understanding of vascular morphogenesis in general. The results demonstrate that the TIE2-VM forms have both common and specific effects on TIE2 and the endothelial cells (ECs) expressing them. Mutation-induced TIE2 autoactivation leading to loss of normal EC monolayer organization due to extracellular matrix (ECM) fibronectin deficiency was found to be a common change. This was shown to occur through chronic activation of the mitogen-activated protein kinase (MAPK) pathway, which also caused activation of the proteolytic plasminogen system. Also, most mutations altered TIE2 trafficking and angiopoietin ligand regulated TIE2 functions, albeit through different mechanisms. Using RNA-screening we showed that the most common sporadic TIE2-VM mutation dysregulates genes affecting vascular development, cell migration and ECM remodeling. PDGFB, a major attractant of vascular mural cells, was found to be strongly attenuated due to chronic activation of Akt, which also increases EC survival, by the TIE2 mutant receptors. To conclude, the results in this thesis reveal genetic, molecular and cellular alterations which may potentiate VM formation. This data provides new information on the pathological mechanisms behind abnormal vascular morphogenesis and should assist the development of new molecular treatment strategies for VM patientsTiivistelmä Laskimoepämuodostumat ovat paikallisia verisuoniston kehityksen häiriöitä. Riippuen niiden koosta ja anatomisesta sijainnista ne voivat aiheuttaa merkittävää haittaa. Epämuodostumat koostuvat laajentuneista, laskimonkaltaisista verisuonista, joissa sileiden lihassolujen kerros on puutteellisesti järjestäytynyt. Yli puolessa tutkituista laskimoepämuodostumista havaitaan mutaatioita verisuonten sisäpinnan endoteelisoluissa ilmenevässä TIE2 reseptorityrosiinikinaasissa, joka säätelee verisuonten kehitystä, muokkausta ja fysiologista toimintaa. TIE2-mutaatioiden aiheuttamia molekyyli- ja solutason muutoksia tai niiden yhteyttä epämuodostumien syntyyn ei ole aikaisemmin tunnettu. Tämän tutkimuksen tarkoituksena oli selvittää, miten laskimoepämuodostumista löydetyt mutaatiot vaikuttavat TIE2-reseptorin toimintaan molekyyli- ja solutasolla sekä TIE2-reseptorista alkavaan solunsisäiseen viestintään. Koska pysyvää hoitomuotoa laskimoepämuodostumille ei tunneta, voisi tieto niiden taustalla olevista patologisista mekanismeista edesauttaa parempien, ei-kajoavien hoitomuotojen kehittämisessä ja antaa myös yleisesti uutta tietoa verisuoniston kehityksestä. Väitöskirjan tulokset osoittavat, että mutaatiot vaikuttavat TIE2-reseptoriin ja sitä ilmentäviin endoteelisoluihin mutaatioille yhteisillä sekä mutaatiokohtaisilla tavoilla. Mutaatioille tyypillinen TIE2-reseptorin ligandista riippumaton aktivaatio aiheutti aktivaation nousun myös TIE2:sta alavirtaan olevissa viestinvälittäjissä. Tämä puolestaan johti fibronektiini-proteiinin häviämiseen soluväliaineesta, sileitä lihassoluja säätelevän PDGFB-kasvutekijän ilmenemisen laskuun ja solujen ohjelmoidun solukuoleman vähenemiseen. Useimmat tutkitut mutaatiot muuttivat myös TIE2-reseptorin sijaintia soluissa häiriten TIE2:n angiopoietiini-ligandien säätelemiä toimintoja usean eri mekanismin kautta. Transkriptomin laajuiset RNA-tutkimukset osoittivat monien verisuonten kehitykseen, solujen liikkumiseen ja soluväliaineen muokkaukseen liittyvien geenien ilmentymisen muuttuneen. Lopputuloksena tutkimus paljasti geeni-, molekyyli-, ja solutason muutoksia, jotka saattavat vaikuttaa laskimoepämuodostumien syntyyn. Tulokset antavat lisätietoa sairautta aiheuttavista mekanismeista verisuoniston kehityksen häiriöiden taustalla ja ovat hyödyksi kehitettäessä uusia lääkkeitä laskimoepämuodostumien molekulaarisia hoitoja varten
13
Hughes, David Paul. "A study of the receptor tyrosine kinase Tie2 and its interaction with novel signalling intermediates." Thesis, University of Leicester, 2003. http://hdl.handle.net/2381/29460.
Full textAbstract:
The receptor tyrosine kinase Tie2 is expressed predominantly in endothelial cells and has a role in blood vessel formation, remodelling and maturation. This receptor also has anti-apoptotic and anti-inflammatory effects on endothelial cells. To delineate the signalling pathways utilised by Tie2 two approaches were used. The first approach involved the use of Tie2 chimeric receptors in order to gain control over Tie2 activation. When transiently expressed in endothelial cells Tie2 chimeric receptors were autophosphorylated and insensitive to further increases in tyrosine phosphorylation following ligand treatment. In stable cell lines Tie2 chimeras showed reduced levels of autophosphorylation but once again were insensitive to further increases in tyrosine phosphorylation following ligand treatment. Furthermore stably expressed Tie2 chimeras could not be readily immunoprecipitated and so this approach was deemed unsuitable for determining Tie2 interacting proteins. The second approach was to use the yeast 2-hybrid system to screen a human endothelial cell cDNA library. This screen identified a novel protein, termed FL9.1 that interacted with the intracellular domain of Tie2. FL9.1 was found to represent the human homologue of the recently described murine A20 binding inhibitor of NFkB activation-2 (ABIN-2). FL9.1 was determined not be endothelial cell specific, to bind Tie2 in a phosphotyrosine-dependent manner but not become tyrosine phosphorylated by Tie2. Furthermore FL9.1 was shown to bind specifically to Tie2 but not Tiel. Deletion analysis showed that within FL9.1 amino acid residues 171-272 are required for Tie2 binding. NFkB regulates genes participating in immune and inflammatory responses. Expression of FL9.1 deletion mutants in human endothelial cells suppressed the ability of the Tie2 activating ligand angiopoietin-1 to inhibit phorbol ester-induced NFkB-dependent reporter gene activity. These findings represent a potentially novel Tie2 signalling pathway and may be the pathway through which Tie2 exerts its anti-inflammatory actions in endothelial cells.
14
Neuhauß, Anne-Kathrin [Verfasser]. "Die Bedeutung der Angiopoietine-1 und -2 und ihres Rezeptors Tie2 in der Pneumokokkenpneumonie / Anne-Kathrin Neuhauß." Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1078505292/34.
Full text
15
Souza, Aline Friedrichs de. "Expressão das angiopoietinas 1 e 2 e do receptor TIE2 em fígados de pacientes com atresia biliar." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/87171.
Full textAbstract:
A atresia biliar (AB) é uma doença da infância caracterizada por uma colangiopatia esclerosante progressiva que leva à obstrução biliar. O tratamento de escolha é a portoenterostomia, cujo prognóstico é relacionado à idade do paciente na época da cirurgia e a variáveis histológicas como a extensão da fibrose e da reação ductular. O espessamento da túnica média (TM) sugere uma arteriopatia na patogenia da AB. Nós avaliamos a expressão do sistema angiopoietinas (ANGPT)/receptor tirosinaquinase com domínios imunoglobulina e EGF(endotelial growth fator) like (Tie2) no fígado de pacientes com AB e com colestase intra-hepática (CIH), correlacionando com espessamento da TM, com variáveis associadas a gravidade da doença e com o prognóstico pós operatório. Métodos - A expressão da ANGPT1, ANGPT2 e Tie2 foi feita com o método de PCR quantitativo em amostras de fígado obtidas de pacientes com AB (n23) na ocasião da portoenterostomia e de crianças de idade semelhante com CIH (n7). As variáveis histológicas foram analisadas por método morfométrico. Resultados - A ANGPT1 e a ANGPT2 apresentaram expressão aumentada no grupo com AB em comparação com o grupo com CIH (P=0,024 e P=0,029, respectivamente). No grupo com AB, a expressão das ANPTs correlacionouse positivamente com a espessura da TM (ANGPT1: rs=0,59, P=0,013; ANGPT2: rs=0,52, P=0,032) e não teve correlação com variáveis associadas a gravidade da doença. O Tie2 e as ANGPTs correlacionaram-se negativamente (ANGPT1: rs=-0,73, P<0,001; ANGPT2: rs=-0,54, P=0,007). Conclusão - Na AB há uma expressão aumentada da ANGPT1 e da ANGPT2 e uma correlação positiva desta expressão com a espessura da TM, mas, não com a idade na ocasião da portoenterostomia ou com variáveis histológicas associadas com a gravidade da doença na época do procedimento.Background- Biliary atresia (BA) is an infantile disorder characterized by progressive sclerosing cholangiopathy leading to biliary obstruction. First line treatment of BA is hepatoporto-enterostomy, whose prognosis is related to age at surgery and to histologic variables such as extent of fibrosis and ductular reaction. Hepatic arterial medial thickening (MT) suggests an arteriopathy in BA pathogenesis. We evaluated the expression of angiopoietin (ANGPT)/tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie2) system in livers from patients with BA, correlating with MT, variables associated with disease severity and postoperative prognosis. Methods- ANGPT1, ANGPT2 and Tie2 expressions were assessed by qPCR in liver samples obtained from BA patients (n=23) at portoenterostomy and age-matched infants with intrahepatic cholestasis (IHC, n=7). Histologic variables were morphometrically assessed. Results- ANGPT1 and ANGPT2 were overexpressed in BA in comparison with IHC (respectively, P=0.024 and P=0.029). In BA, ANGPTs′ expression was positively correlated with MT (ANGPT1:rs=0.59, P=0.013; ANGPT2:rs=0.52, P=0.032), not with variables associated with disease severity. Tie2 and ANGPTs′ expressions were negatively correlated (ANGPT1: rs=-0.73, P<0.001; ANGPT2: rs=- 0.54, P=0.007). Conclusion- In BA there is overexpression of both ANGPT1 and ANGPT2 correlated with MT but not with age at portoenterostomy or with the histological variables associated with disease severity at the procedure.
16
Cordeiro, Ana Lúcia Marinho. "Characterization of the expression of Ang1, Ang2 and Tie2 in the corpus cavernosum of the Rat during aging." Dissertação, Faculdade de Medicina da Universidade do Porto, 2009. http://hdl.handle.net/10216/50118.
Full text
17
Cordeiro, Ana Lúcia Marinho. "Characterization of the expression of Ang1, Ang2 and Tie2 in the corpus cavernosum of the Rat during aging." Master's thesis, Faculdade de Medicina da Universidade do Porto, 2009. http://hdl.handle.net/10216/50118.
Full text
18
Pietilä, R. (Riikka). "Angiopoietin 1 and 2-regulated Tie2 receptor translocation in endothelial cells and investigation of Angiopoietin-2 splice variant 443." Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526207971.
Full textAbstract:
Abstract Angiopoietins 1 and 2 (Ang1 and Ang2) are the ligands of the Angiopoietin/Tie signalling system, which is a binary pathway offering mechanisms for healthy vessels to reach and maintain their quiescence but also to rapidly respond to activating stimuli leading to a remodelling of endothelium. The latter is linked to disease settings such as inflammation and cancer where endothelial cell (EC) integrity is compromised and is often related to an increase in Ang2 expression. This study focused on the mechanisms enabling Ang1 to mediate both EC stability and migration and molecular and cellular determinants for ligand-specific functions of Ang2 and its isoform Ang2443. The findings revealed that Ang1 induces differential signalling depending on whether it anchors and activates Tie2 in cell-cell junctions in quiescent ECs, or in cell-matrix contacts in mobile ECs, thus leading to cellular phenotypes characteristic of resting and mobile ECs, respectively. In the second part of the thesis Ang2-Tie2 specific cell-extracellular matrix (ECM) contact sites were studied. Formation of Ang2/Tie2 EC-ECM contact sites was dependent on the collagen I and IV matrices, low Ang2 oligomerization state, α2β1-integrins, and intact microtubules. In the third part of the thesis the comparison of Ang2 mRNA splice variant Ang2443 with full length Ang2 (Ang2FL) revealed both redundant and ligand form–specific effects, expression of Ang2443443 increased the amount of monomeric ligand forms due to proteolytic processing and promoted transendothelial migration of cancer cells in vitro. On the other hand, both Ang2443 and Ang2FL were stored in endothelial Weibel-Palade bodies (WPBs), similarly induced Ang2-specific Tie2 cellular redistribution, and were mostly comparable in developmental angio- and lymphangiogenesisTiivistelmä Angiopoietiinit 1 ja 2 (Ang1 ja Ang2) ovat Ang/Tie signalointireitin kasvutekijöitä. Ang1 kasvutekijää tarvitaan sydämen ja verisuoniston sikiöaikaiseen kehittymiseen, se vähentää Tie2 reseptorin kautta verisuonten läpäisevyyttä, mutta edistää myös yksittäisten endoteelisolujen liikkumista. Saman Tie2 signalointireitin toisen kasvutekijän Ang2:n ilmeneminen johtaa verisuonten läpäisevyyden kasvuun tulehduksessa, uusien verisuonten muodostumiseen syöpäkasvaimissa ja syöpäsolujen leviämiseen elimistössä. Väitöskirjatutkimuksessa selvitettiin niitä solutason mekanismeja, joilla Ang1 kykenee välittämään sekä endoteelisolujen tiiviyttä että liikkumista. Lisäksi tutkittiin niitä molekyyli- ja solutason mekanismeja, joilla Ang2 ja sen isomuoto Ang2443 välittävät kasvutekijäspesifisiä vaikutuksiaan. Väitöskirjassa osoitettiin että Tie2 reseptori paikantuu verisuonten endoteelisoluissa Ang1 sitoutumisen seurauksena joko solu-soluliitoksiin, tai yksittäisissä endoteelisoluissa solu-soluväliaine rajapinnalle. Tie2:n siirtyminen solu-soluliitoksiin aktivoi soluissa signalointireittejä, jotka ovat tyypillisiä normaaleille tiiviille verisuonille ja solu-soluväliaineliitoksissa liikkuville endoteelisoluille tyypillisiä piirteitä. Väitöskirjatyön toisessa osassa tutkittiin Ang2:lle ominaisia vaikutuksia ja Ang2-Tie2 kompleksin paikantumista erityisiin solu-soluväliaineliitoksiin. Tämä oli riippuvaista Ang2:n oligomerisaatiosta, kollageenisoluväliaineesta, α2β1-integriinistä ja normaalista mikrotubulusverkostosta. Väitöskirjatyön kolmannessa osassa osoitettiin että Ang2443 isomuodolla on sekä yhteisiä että isomuotospesifisiä piirteitä verrattuna kokopitkään Ang2:een (Ang2FL). Liukoinen Ang2443, mutta ei Ang2FL, esiintyi yleisesti monomeerisenä ligandimuotona proteiinin multimerisaatio-osan pilkkomisen seurauksena. Ang2443 lisäsi myös syöpäsolujen liikkumista endoteelisolujen läpi. Toisaalta sekä Ang2443 että Ang2FL varastoitiin endoteelisoluissa Weibel-Palade varastokappaleisin, ne välittivät samanlaista Tie2 reseptorin paikantumista endoteelisoluissa ja toimivat pääsääntöisesti samanlaisina kasvutekijöinä veri- ja imusuonten kehityksen aikana hiiressä
19
Aguirre, Palma Luis Mario [Verfasser]. "Angiopoietine modulieren molekulare und zelluläre Schlüsselprozesse in den chronischen lymphatischen Leukämie Zellen durch Tie2-unabhängige Mikroumgebungs-Signalwege / Luis Mario Aguirre Palma." Köln : Deutsche Zentralbibliothek für Medizin, 2016. http://d-nb.info/1118626362/34.
Full text
20
Pötzsch, Birgit [Verfasser]. "Die Bedeutung des Ang2-Tie2-Signalweges für die Interaktion von malignen B-Lymphozyten mit ihrer Mikroumgebung bei der chronischen lymphatischen Leukämie (CLL) / Birgit Pötzsch." Köln : Deutsche Zentralbibliothek für Medizin, 2014. http://d-nb.info/1056004169/34.
Full text
21
van, Wijngaarden Peter, and petervanwijn@yahoo com au. "Heritable influences in oxygen-induced retinopathy." Flinders University. Medicine, 2006. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20060824.211102.
Full textAbstract:
Retinopathy of prematurity, a disease characterised by aberrant retinal vascular development in premature neonates, is a leading cause of blindness and visual impairment in childhood. This work sought to examine differences in the susceptibility of inbred rat strains to oxygen-induced retinopathy, a model of human retinopathy of prematurity. The overriding aim was to identify genetic factors in rats that might be generalisable to humans.
Newborn rats of six different strains were exposed to alternating cycles of hyperoxia and relative hypoxia for fourteen days. Rats were removed to room air and killed for analysis immediately, to assess oxygen-induced retinal vascular attenuation, or four days later to evaluate the extent of hypoxia-induced vasoproliferation. Whole flat-mounted retinae were stained with fluorophore conjugated isolectin GS-IB4, and measurement of vascular area was conducted using fluorescence microscopy and video-image analysis. A hierarchy of susceptibility to the inhibitory effects of cyclic hyperoxia and relative hypoxia on postnatal retinal vascularization was identified for the rat strains studied. Susceptibility to vascular attenuation was predictive of the subsequent risk of vascular morphological abnormalities. Cross-breeding experiments between susceptible and resistant strains demonstrated that the susceptible phenotype was dominantly inherited in an autosomal fashion. These studies confirmed an association between ocular pigmentation and retinopathy risk, however the finding of differential susceptibility amongst albino rat strains implicated factors in addition to those associated with ocular pigmentation.
Quantitative real-time reverse transcription-polymerase chain reaction was used to compare the retinal expression of angiogenic factor genes in susceptible and resistant strains with the aim of identifying a genetic basis for the strain difference. Eight angiogenic factor genes were selected for study: vascular endothelial growth factor (VEGF); VEGF receptor 2; angiopoietin 2; Tie2; pigment epithelium-derived factor; erythropoietin; cyclooxygenase-2 and insulin-like growth factor-1. The most notable difference between strains was the expression of vascular endothelial growth factor (VEGF) during the cyclic hyperoxia exposure period - higher VEGF expression was associated with relative resistance to retinopathy. Other differences in retinal angiogenic factor gene expression between strains, such as higher expression of VEGF receptor 2 and angiopoietin 2 in resistant strains, appeared to be secondary to those in VEGF. Following cyclic hyperoxia, the expression pattern of angiogenic factor genes changed - messenger RNA levels of hypoxia-induced genes, including VEGF, VEGF receptor 2, angiopoietin 2 and erythropoietin, were significantly higher in those strains with larger avascular areas, than in those strains that were relatively resistant to retinopathy. These findings provide firm evidence for hereditary risk factors for oxygen-induced retinopathy in the rat. Differences in the regulatory effects of oxygen on VEGF expression appear to be central to the risk of retinopathy. The potential relevance of these hereditary factors is discussed in the context of the human disease.
22
Brossoie, Nancy. "The Characteristics and Functions of Weak Ties." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/30236.
Full textAbstract:
The primary purpose of this study was to identify dimensions of weak tie relationships including characteristics (e.g., distinctive qualities, traits, or properties), functions (e.g., outcomes, purposes, or meanings derived from the interaction) and determinants of engagement to gain insight into the weak tie exchange process and develop frameworks that can be used to operationalize the concept. Data were collected through stories provided by participants during face-to-face interviews. Respondents recounted a situation when someone they did not know well and to whom they did not feel particularly close provided them with assistance. Over 70 stories were collected from 50 adults aged 65 and older who were active in their community. Stories collected were analyzed using an inductive approach that was supported by the concepts of interpersonal tie strength, loose connections, social exchange theory, and social support. Findings suggest that weak tie relationships occur in a variety of community settings and in response to a variety of daily challenges. The exchanges occur more frequently with acquaintances than strangers and the initiator of the exchange is generally the person offering support. The types of support offered are broad-based and include instrumental, emotional, and informational support. Weak tie exchanges range from one-time brief interactions to intermittent exchanges over extended periods, depending on the circumstances. Findings also suggest that weak ties have a specific task or purpose, encourage awareness about the value and purpose of social interactions, and influence participantsâ future social interactions. Six factors were identified as determinants of engagement in weak ties: situational factors, personal characteristics, judgments of responsibility, attitudes about helping behaviors, personal network type, and exchange history. The findings from this study provide a foundation for further conceptualization of weak ties and a framework on which to develop instruments to measure tie strength and the potential for engaging in weak tie exchanges.Ph. D.
23
Morin, Mélanie. "Angiogenèse: Nouvelle cible thérapeutique pour les épilepsies partielles pharmacorésitantes." Phd thesis, Université Montpellier I, 2009. http://tel.archives-ouvertes.fr/tel-00421314.
Full textAbstract:
Dans l'épilepsie du lobe temporal (ELT), l'hyperexcitabilité est attribuée à la mort neuronale, la gliose et la plasticité synaptique. Un remodelage vasculaire n'a jamais été recherché dans le tissu épileptique, bien que des données récentes suggèrent que la perméabilité de la barrière hémato-encéphalique (BHE) est épileptogène.Nous avons observé dans l'hippocampe de patients atteints d'ELT réfractaire une dégradation de la BHE, une néo-vascularisation et la surexpression du vascular endothelial growth factor (VEGF) et de son récepteur VEGFR-2.
Pour comprendre cette angiogenèse, nous avons modélisé l'épilepsie in vivo et in vitro chez le rat. In vivo, la néo-vascularisation, la surexpression de VEGF/VEGFR-2 et la rupture de BHE sont présentes dans un modèle avec lésions et gliose, mais transitoires dans un modèle non lésionnel.
In vitro, nous avons observé que des crises déclenchées sur des cultures organotypiques d'hippocampe (COHs) induisent une angiogenèse et une dégradation de BHE qui ne persiste qu'en présence de lésions.
Nous avons étudié le rôle du VEGF in vitro, en le neutralisant ou en inhibant des voies de signalisation de VEGFR-2 dans les COHs, confirmant l'importance de PKC et src dans l'angiogenèse et la dégradation de la BHE. De plus, nous avons montré un déséquilibre des angiopoiétines en faveur d'Ang2 qui potentialise les effets du VEGF.
Chez l'homme et l'animal, la rupture de la BHE persiste dans les foyers chroniques entretenant l'induction des crises. En ciblant des facteurs angiogéniques pour réparer la BHE, nous espérons réduire l'épileptogenèse et donc proposer de nouvelles stratégies pour les épilepsies réfractaires.
24
VanSchalkwijk, Walter A. "Electrolyte properties and interfacial kinetics for the systems Li LiCF3SO3/2MeTHF TiS2 and Li LiCF3SO3/2MeTHF TiSe2." Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/5252.
Full text
25
Alves, Josmary Karoline Demko. "Density in affective and instrumental ties: analyzing the contingencies of tie content on team performance." reponame:Repositório Institucional do FGV, 2016. http://hdl.handle.net/10438/17824.
Full textAbstract:
Submitted by Josmary Karoline Demko Alves (josmarykaroline@yahoo.com.br) on 2016-10-29T19:29:03Z
No. of bitstreams: 1
Dissertação Josmary vfinal.pdf: 958731 bytes, checksum: 99f22613883eb6a31dcd046c8ee98a08 (MD5)Approved for entry into archive by ÁUREA CORRÊA DA FONSECA CORRÊA DA FONSECA (aurea.fonseca@fgv.br) on 2017-01-25T12:38:46Z (GMT) No. of bitstreams: 1 Dissertação Josmary vfinal.pdf: 958731 bytes, checksum: 99f22613883eb6a31dcd046c8ee98a08 (MD5)
Made available in DSpace on 2017-02-02T18:20:37Z (GMT). No. of bitstreams: 1 Dissertação Josmary vfinal.pdf: 958731 bytes, checksum: 99f22613883eb6a31dcd046c8ee98a08 (MD5) Previous issue date: 2016-08-29
Estruturas sociais influenciam a efetividade dos grupos. O propósito deste estudo é explorar os efeitos contingenciais dessa relação por meio da investigação da densidade em diferentes redes na performance das equipes. Hipotetizou-se, primeiramente, o efeito oposto para densidade instrumental e afetiva em performance das equipes; posteriormente, argumenta-se que interdependência das tarefas e a orientação de distância de poder agem como moderadores. Para testar as hipóteses, foram utilizadas informações de questionários coletados de 27 Unidades de Pronto Atendimento (UPA) e 106 grupos. O resultado encontrado suporta o efeito positivo de densidade instrumental e o impacto negativo da densidade afetiva. Além disso, provou-se que a interdependência de tarefas atenua ambas as relações diretas. Ao final, são discutidas as implicações destes resultados para pesquisa em densidade das redes e performance das equipes.
Social structures influence team effectiveness. The purpose of this study is to explore the contingencies effects of this relationship by investigating density in distinct network contents on team performance. We first hypothesized opposite direct effects for instrumental and affective density on team performance; then we further argue that task interdependence and power distance orientation act as moderators. To test our hypotheses we use survey data from 27 Emergency and Care Units and 106 teams. The results support the positive effect of instrumental density and the negative impact of affective density. Moreover, task interdependence was found to attenuate both main relationships. We discuss the implications of these findings for research on network density and team performance.
26
Steele, Karl Christopher. "Evaluation of TiO2 and Ag-TiO2, CuO-TiO2 composite films for self-disinfection activity." Thesis, University of Salford, 2009. http://usir.salford.ac.uk/26923/.
Full textAbstract:
The removal or killing of microorganisms on surfaces is of concern in the health care setting, food preparation areas and general work environment. The use of TiO2 photosterilisation has been proposed as an alternative to chemical disinfection of surfaces as a means to reduce the need for increasingly concentrated and aggressive chemicals necessary to kill disinfectant-resistant organisms. The objective of this research was to evaluate the ability of photocatalytic oxidation to reduce bacterial and viral contaminants on surfaces coated with TiOa and Ag-TiC^, TiO2-Ag, Cu-TiC^, TiO2-Cu. There are no British Standards that cover evaluation of such surfaces. A method for evaluation of photocatalytic surfaces was therefore developed from BS EN 13697:2001 and used to evaluate the activities of a variety of catalytic surfaces coated with TiO2, Ag and Cu and multi-layers of Ag-TiO2,TiO2-Ag, Cu-TiO2,TiO2-Cu. The antimicrobial activities were found to be dependent on the nature of the coating. Highest killing activities were obtained with Ag and Cu alone but combinations of Ag or Cu with TiO2were more active than TiO2 alone and also retained some self- cleaning activity. The results showed that the developed method was adaptable for determination of the antimicrobial activity of coatings with a wide range of activities producing 100% killing of Escherichia coll in times from 3 min up to 4 h. The results showed that it was possible to produce self cleaning self disinfecting surfaces and that surfaces with TiO2 on top, although having reduced activity compared to Ag or Cu, were durable and may have applications in the prevention of transmission of infections on surfaces in a wide range of applications.
27
Ebrahim, I. "The lateral load carrying capacity of wall ties used in cavity wall construction in the Western Cape : a comparison between the Butterfly-type wire tie and the Crimped-type wire tie." Master's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/7703.
Full textAbstract:
Bibliography: leaves 69-71.The aim of the testing was to compare the relative positives and negatives of the Butterfly Tie and the Crimped lie as regards to water transfer, tensile and compression strengths based on the Australian Code [AS 2699-l 984] requirements as it is more comprehensive. The reason was because the Butterfly Tie has been promoted in cavity wall construction in South Africa for a number of reasons, for example: * NHBRC (National Home Builders Registration Council) compels contractors to use the Butterfly Tie * SABS 28:l986 and SABS O 164-1 :1980 also compel the use of Butterfly Tie, even though there is an anomalous statement in the specifications. Another reason was because the use of the Crimped Tie was not being promoted in cavity wall construction in South Africa mainly because of a lack of information regarding characteristic strength and its resistance to water transfers. The following tests, based on the Australian Code, which is more stringent than the South African Codes were then carried out on the Butterfly Tie and the Crimped Tie: * Tests for water transfer * Tests tor compression and tensile strengths using couplets * Tests for compression and tensile strengths using ties only. Although the testing showed that the Butterfly Tie and the Crimped Tie fulfilled the requirements of the Australian Code, there were negative aspects relating to the Butterfly Tie. It is recommended that serious considerations be given by the South African Bureau of Standards to include the Crimped Tie in its Code of Practice for Cavity Walls.
28
McHenry, Michael T. "PRESSURE MEASUREMENT AT THE BALLAST-TIE INTERFACE OF RAILROAD TRACK USING MATRIX BASED TACTILE SURFACE SENSORS." UKnowledge, 2013. http://uknowledge.uky.edu/ce_etds/15.
Full textAbstract:
The pressure distribution at the ballast-tie interface of railroad track plays a key role in overall track support. Failure of the ballast or tie can result from excessive loads that were not designed for, requiring increased maintenance and reducing railroad operating efficiency. Understanding the forces acting on the ballast and tie are required to design higher performance and longer lasting track. To further this understanding, the use of Matrix Based Tactile Surface Sensors (MBTSS) is employed to measure the actual pressure distribution at the ballast-tie interface, characterized by individual ballast particle contact points and non-uniform pressures. The research explores this application of MBTSS including the development of sensor protection and calibration procedures. Results from laboratory ballast box testing conducted at the Transportation Technology Center, Inc. (TTCI) are presented. Conservative estimates of peak pressure under a typical wheel load on new ballast averaged 1450 psi and on fouled ballast averaged 680 psi. Contact areas varied across the range of ballast gradations and are shown to increase under increased applied load. A parameter to describe the "roughness" of the ballast-tie pressure distribution is offered. Results from in-track testing performed at TTCI, including pressure distributions along ten test ties, are also presented.
29
Bartolone, Emily R. "Relationship Ties." Kent State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=kent1619427633784485.
Full text
30
Loury, Sharon D. "Family Ties." Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etsu-works/8201.
Full text
31
Pacheco, e. Silva Viviane. "Atividade fotocatalitica de TiO2 em matrizes de siloxano." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250504.
Full textAbstract:
Orientadores: Inez Valeria Pagotto Yoshida, Wilson de Figueiredo JardimTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-13T12:54:30Z (GMT). No. of bitstreams: 1 PachecoeSilva_Viviane_D.pdf: 3480980 bytes, checksum: 4c99b3d79e0972f6849d577fd58e285e (MD5) Previous issue date: 2009
Resumo: Este trabalho relata a imobilização do TiO2 em matrizes de siloxano, como alternativa ao emprego do TiO2-pó em suspensão, para a fotodegradação de espécies orgânicas em solução aquosa, sob radiação UV-Vis ou radiação solar, tendo o ácido salicílico (AS) como modelo de poluente. Incorporou-se o TiO2-pó em uma matriz elastomérica de silicona com grau de reticulação relativamente baixo, obtida a partir de goma de poli(dimetilsiloxano) de alta massa molar, obtendo-se compósitos elastoméricos na forma de monólitos. O TiO2-pó também foi incorporado em uma matriz de silicona altamente reticulada, na presença de um agente porogênico, obtendo-se um compósito monolítico rígido e poroso, com características de ¿ceramer¿. Sintetizou-se ainda o TiO2 in situ na forma anatásio, por síntese hidrotérmica, empregando-se como matriz os compósitos contendo TiO2-pó, e placas porosas de vidro. Comparando-se a eficiência dos compósitos elastoméricos com diferentes composições, frente à fotodegradação do AS, sugeriu-se que apenas os sítios de TiO2 mais próximos da superfície iluminada tiveram acesso à radiação UVVis. Apesar das amostras com matriz elastomérica terem apresentado os maiores valores de sorção de AS, o material que apresentou a maior eficiência fotocatalítica sob radiação UV-Vis, superando inclusive o desempenho do TiO2-pó, foi o compósito poroso contendo também o TiO2 gerado in situ, provavelmente devido a sua maior área superficial. Os experimentos conduzidos com esse compósito sob radiação solar evidenciaram uma diminuição na porcentagem de fotodegradação do AS, provavelmente pela menor intensidade da radiação solar, em relação à lâmpada UVVis, associada ao efeito da atenuação da radiação no monólito. Observou-se um pequeno aumento na atividade fotocatalítica do TiO2 com o aumento no tamanho dos cristalitos de anatásio sintetizados in situ, após o tratamento térmico das placas porosas de vidro a 600°C. Os resultados apresentados neste estudo sugerem grande potencialidade na imobilização do TiO2 em matrizes de silicona, tanto pela incorporação do TiO2-pó, quanto pela síntese in situ da fase anatásio
Abstract: This study reports the immobilization of TiO2 in siloxane matrices, as an alternative to the use of TiO2-powder in suspension, for the photodegradation of organic species in aqueous solution, under UV-Vis radiation or solar radiation, having the salicylic acid (SA) as model pollutant. TiO2-powder was incorporated in an elastomeric silicone matrix with a relatively low crosslinking degree, obtained from a poly(dimethylsiloxane) gum with high molecular weight, giving rise to monolithic elastomeric composites. TiO2-powder was also incorporated in a silicone matrix with a high crosslinking degree, in the presence of a pore forming agent, resulting in a hard and porous monolithic composite, with ¿ceramer¿ characteristics. TiO2 in the anatase form was obtained in situ, by hydrothermal synthesis, on the previously prepared composites containing TiO2-powder, and also on glass porous plates. Comparing the efficiency of the elastomeric composites with different compositions, in relation to the SA photodegradation, the results suggested that only the TiO2 sites near the illuminated surface were accessed by the UV-Vis radiation. Although the samples with the elastomeric matrix presented the highest SA adsorption values, the porous composite containing the in situ obtained-TiO2 presented the highest photocatalytic efficiency, with better performance than the TiO2-powder, probably due to the high surface area of this material. When this porous composite was tested under solar radiation, the lower intensity of this radiation, in relation to the UV-Vis lamp, associated to the radiation attenuation effect in the monolith, promoted a decrease in the percentage of SA photodegradation. An increase in the size of the in situ obtained-anatase crystallites, promoted by the thermal treatment of the glass porous plates at 600°C, resulted in an increase in the photocatalytic activity of the TiO2. The results presented in this study suggest a great potential in the immobilization of TiO2 in silicone matrices, either by the incorporation of TiO2-powder, as by the in situ synthesis of the anatase form
Doutorado
Quimica Inorganica
Doutor em Ciências
32
Santos, Ana Camila Santos dos. "Produção de eletrodos por modificações superficiais de Ti e caracterização do seu desempenho na intercalação de Li+." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/143823.
Full textAbstract:
Neste trabalho foram estudadas diferentes modificações superficiais do titânio (Ti) como método de preparação de superfícies de eletrodos para baterias de íons lítio (Li+) Inicialmente, as modificações foram produzidas pelas micro-indentações, com posterior corrosão eletroquímica por pites em soluções de brometo. As superfícies polidas, tratadas termicamente e modificadas através de micro-indentações foram avaliadas em diferentes parâmetros, tais como o potencial aplicado, concentração dos íons agressivos no eletrólito, temperatura, tempo dos testes e principalmente, sobre o impacto das deformações causadas pela força indentações para localização de orifícios produzidos por pites. Filmes porosos de titânia (TiO2) crescidos sobre o Ti puro, foram produzidos por anodização a plasma (anodização por centelhamento ou sparking) em 1M H3PO4 e em 1M Na2SO4 e por anodização nanotubular em 1M H3PO4 + 1M NaOH + 0,4 %(peso) HF. Os resultados mostraram, em óxidos tipo “esponja” formados na anodização a plasma em 1M H3PO4 e 1M Na2SO4, a incorporação de elementos do eletrólito contendo, respectivamente, P e S, numa relação de P/O > S/O e em óxidos nanotulares, a predominante incorporação de elemento de F. Posteriormente, as superfícies corroídas por pites e as superfícies de óxidos crescidos por anodização a plasma foram convertidas por sulfetação em diferentes materiais micro e nanoestruturados compostos por sulfetos e oxisulfetos de titânio, ajustando-se as condições de processo. O desenvolvimento proposto mostrou que é possível modificar a composição química do óxido formado por anodização a plasma para nanocristais de TiS2, nanofitas de TiS3 e TiOxSy, sem danificar a morfologia original dos nanoporos de TiO2. Os compostos formados podem ser usados como eletrodos nanoarquiteturados tridimensionais (3D) para microbaterias de íons lítio (Li+) com alta densidade de potência. A síntese desses compostos é realmente promissora, porque eles têm a capacidade de inserir mais íons lítio do que TiO2 puro, resultando em uma melhoria na capacidade das microbaterias.In this study, different surface modifications of titanium (Ti) were studied as a method of surface preparation of electrodes for ion lithium batteries (Li+). Initially, the modifications were produced by micro-indentation with subsequent electrochemical pitting corrosion in solutions of bromide. The polished surfaces, heat treated and modified through micro indentations were evaluated for different values of parameters, such as applied potential, concentration of aggressive ions in the electrolyte, temperature, polarization time, and mainly intensity of the deformation caused by indentations for localizing holes produced by pitting. It was expected the adjust of location of these parameter settings promotes nucleation of pits, according to the pattern of indentations and growth of pitting depth for increased surface area. Porous films of titania (TiO2) were produced on pure Ti by plasma anodization (or sparking) in 1M H3PO4 and 1M Na2SO4. Nanotubes were synthesized by porous anodization in 1M NaOH + 1M H3PO4 + 0.4 (wt%) HF. The results showed oxide "sponge" like formed by plasma anodization, incorporating elements of the electrolyte containing respectively, P and S in a ratio P/O> S/O and, in nanotubular oxides, with predominant incorporation of F. Subsequently, the pitted surfaces and the surfaces of oxides grown by plasma anodization were converted by sulfidation into different micro and nanostructured materials consisting of titanium sulfide and oxisulfides by adjusting the process conditions. The proposed development has shown that it is possible to modify the chemical composition of the oxide formed by plasma anodizing to nanocrystals of TiS2 and nanobelts of TiS3 and TiOxSy without damaging the original morphology of the nanoporous TiO2. The formed compounds can be used as three-dimensional (3D) nanoarchitectured electrodes for ion lithium batteries (Li+) with high power density. The synthesis of these compounds is promising due to a higher ability to intercalate more ions lithium than pure TiO2, resulting in an improvement in the capacity of microbatteries.
33
Christensen, Diana Law. "Analysis of Ties, Tie Systems, and Attachment Methods of Fibrous Sandals of Tsegi Phase (Pueblo III) Kayenta Branch, from Tsegi Canyon, Arizona." DigitalCommons@USU, 1993. https://digitalcommons.usu.edu/etd/7432.
Full textAbstract:
Forty-three Pueblo III sandals and sandal fragments from four sites in Tsegi Canyon, Arizona, were analyzed to develop tie terminology, identify possible correlation of tie system to sandal construction, and identify characteristics for future tie research. Each piece of sandal tie cordage was analyzed for tie system type, tie attachment method, and tie cordage structure.
Three overall tie systems were found: toe-heel tie systems (nine sandals), criss-cross tie system (one sandal), and side loop tie systems (fifteen sandals) Five additional sandals (narrow, two-warp plainweave construction) had possible toe-heel tie systems. Tie systems of six sandals were not distinguishable between toe-heel and criss-cross. Five sandals had unidentifiable tie fragments, and two sandals had no tie information.
Terminology had to be developed for several tie components. Toe loops were found with a single loop (either intact or tied over the toe) and multiple loops (overlapping, adjacent, or parallel). Side loops were overlapping (continuous, mirror image, or reversing), adjacent, and parallel. Ankle/heel loops included single, double, and double intertwined horizontal loops (back of heel), and two vertical loops (side of heel). Loop variations for two-warp plainweave were through weft, around weft, flat loop, and upright loop. Numerous attachment methods were used for the toe, ankle/heel, and side loops, including sole knots and running stitches.
Tie materials included four constructions of leaf: unprocessed leaf, S-twist leaf, Z-twist leaf, and plied leaf (Z-2S, S-2Z, Z-3S). Twelve constructions of yarn were identified, including two- and three-ply yarns of various twist combinations, re-plied yarn, and splicing. Toe-heel and criss-cross tie system sandals tended to have only one cordage type used on an individual sandal; side loop system sandals tended to have several cordage types used on an individual sandal.
A comparison of tie system and sandal construction methods revealed that coarse-braided and two-warp plainweave sandals more frequently used the toe-heel system. Fine-braided and four-and five-warp plainweave sandals used the toe-heel and side loop systems nearly evenly.
Markers for future tie researchers to examine include number of toe loops, types and attachment methods of toe and side loops, and style variations and attachments of ankle/heel loops.
34
Fessi, Nidhal. "Intensification de la dégradation de polluants organiques par photocatalyse dans des émulsions de Pickering." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1352/document.
Full textAbstract:
Ce travail de thèse examine une nouvelle méthode prometteuse pour la dépollution efficace des eaux contaminées par des polluants organiques insolubles de type toluène, 1-méthylnaphtalène, nitrobenzène,…. Cette méthode d’oxydation avancée repose sur la photocatalyse hétérogène dans des émulsions de Pickering. Dans ce type d’émulsions, les tensioactifs stabilisants des gouttelettes huileuses sont remplacés par des nanoparticules solides à propriétés photocatalytiques élevées. Par ailleurs, ces nanoparticules solides doivent remplir les conditions de mouillabilité partielle dans les deux phases aqueuse et huileuse grâce à un équilibre hydrophile-hydrophobe à leur surface. Pour cette raison, le dioxyde de titane (TiO2) anatase a été préparé par la méthode sol-gel puis modifié par fluoration pour obtenir le catalyseur TiO2-F. L’objectif est de formuler des émulsions de Pickering de type huile dans l’eau (H/E) à partir de polluants organiques de faible solubilité dans l’eau. Les catalyseurs synthétisés ont été caractérisés par XRD, BET, SEM, DRS, XPS, et TG-TD-MS. Il a été montré que la fluoration apporte des changements importants dans les propriétés optiques du TiO2 et a amélioré l’équilibre hydrophile/hydrophobe à sa surface de façon significative. Par ailleurs, les résultats obtenus indiquent que des émulsions de Pickering stables peuvent être formulées en utilisant des particules de TiO2 ou TiO2-F de taille nanométrique. Le type et la stabilité des émulsions dépendent de la mouillabilité des nanoparticules stabilisantes évaluées par des mesures d'angle de contact. La mouillabilité des nanoparticules a été trouvée fortement dépendante du type d’huile en raison des contributions de la polarité et des interactions spécifiques avec les polluants. L'étude des émulsions de Pickering par conductivité électrique, microscopie optique et diffusion de la lumière a montré qu'une stabilité élevée a été obtenue dans des conditions de mouillage partiel : angle de contact dans l'eau compris entre 70 et 110°. L’évolution de la taille des gouttelettes d'huiles avec le rapport de masse huile/photocatalyseur a confirmé une forte adsorption des nanoparticules de catalyseur sur les gouttelettes d'huiles. Finalement, les émulsions jugées stables ont été photodégradées sous rayonnement UV. La cinétique de photodégradation des polluants organiques mesurée par HPLC a montré que la dégradation a été intensifiée en utilisant les émulsions de Pickering par rapport aux systèmes non émulsionnés. Ces résultats ont prouvé que l’utilisation des émulsions de Pickering stabilisées par des nanoparticules de dioxyde de titane constituait un moyen efficace et innovateur pour intensifier la dégradation photocatalytique des polluants organiquesThis thesis examines a promising new method for the effective depollution of water contaminated by insoluble organic pollutants such as toluene, 1-methylnaphthalene, nitrobenzene, etc. This advanced oxidation method is based on heterogeneous photocatalysis in Pickering emulsions. In this type of emulsion, the stabilizing surfactants of the oily droplets are replaced by solid nanoparticles having high photocatalytic properties. Moreover, these solid nanoparticles must fulfill the conditions of partial wettability in both aqueous and oily phases thanks to a hydrophilic-hydrophobic balance on their surface. For this reason, the titanium dioxide (TiO2) anatase was prepared by the sol-gel method and then modified by fluorination to obtain the TiO2-F catalyst. The objective is to formulate Pickering oil-in-water (O/W) emulsions from organic pollutants of low water solubility. The synthesized catalysts were characterized by XRD, BET, SEM, DRS, XPS, and TG-TD-MS. It has been shown that fluorination brings about important changes in the optical properties of TiO2 (change in band gap) and improves the hydrophilic / hydrophobic balance at its surface significantly. Moreover, the obtained results indicate that stable Pickering emulsions can be formulated using TiO2 or TiO2-F nanoparticles. The type and stability of the emulsions depend on the wettability of the stabilizing nanoparticles evaluated by contact angle measurements. The wettability of the nanoparticles has been found to be highly dependent on the type of oil due to the contributions of polarity and specific interactions with pollutants. The study of Pickering emulsions by electrical conductivity, optical microscopy and light scattering showed that high stability was obtained under partial wetting conditions: contact angle in water between 70 and 110°. The change in the size of the oil droplets with the oil/photocatalyst mass ratio confirmed a strong adsorption of the catalyst nanoparticles on the oil droplets. Finally, the judged stable emulsions were photodegraded under UV radiation. The photodegradation kinetics of organic pollutants measured by HPLC showed that degradation was intensified using Pickering emulsions compared to non-emulsified systems. These results have shown that the use of Pickering emulsions stabilized by titanium dioxide nanoparticles is an effective and innovative way to intensify the photocatalytic degradation of organic pollutants
35
Kashiwaya, Shun. "Science de surface et propriétés chimiques d'hétérostructures NiO/TiO2 monocristallin." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0241/document.
Full textAbstract:
Les photocatalyseurs à base de TiO2 ont été l’objet d’une grande attention comme une méthode durable de purification de l’air ou de l’eau, et de production d’hydrogène par décomposition de l’eau. Une stratégie avantageuse consiste à développer des héterostructures par couplage avec un autre oxyde métallique former une jonction de type Schottky ou avec un autre oxyde métallique pour créer une jonction p-n à l’interface de manière à prévenir les recombinaisons via une séparation de charge « vectorielle » à ces jonctions. De plus, les facettes cristallines jouent un rôle crucial dans le piégeage des porteurs de charge et, donc,dans les réactions rédox photoactivées. Ainsi, le dépôt sélectif de métal ou d’oxyde métallique sur des facettes spécifiques de nanocristaux de TiO2 devrait augmenter l’activité photocatalytique par l’amélioration de la séparation des charges. Dans ce travail, nous avons combiné l’emploi du cocatalyseur de type p NiO pour former des jonctions p-n avec son dépôt sélectif sur des nanocristaux de TiO2 anatase exposant des facettes bien définies. Par ailleurs, des expériences modèles de physique de surface ont été menées pour étudier les propriétés électroniques de ces hétérojonctionsTiO2 photocatalysts have attracted attention as a sustainable method for water/air purification and hydrogen production by water splitting. An advantageous strategy is the development of heterostructures by coupling metal oxides to create a p-n junction at their interface in order to prevent there combination by vectorial charge carrier separation at these energy junctions. In addition, crystal facets play a decisive role in the trapping of charge carriers and thus photocatalytic redox reactions. Thus, selective deposition of metal or metal oxides onto specific facets would enhance the photocatalytic activity by improving charge separation. In this work, we have combined the usage of p-type NiO co-catalyst to form p-n junction with its selective deposition onto the specific facet of oriented TiO2nanocrystal photocatalysts. Furthermore, the physical model experiments have been performed to investigate the electronic properties of these heterojunctions
36
Paušová, Šárka. "Elaboration de matériaux composites photocatalytiquement actifs pour des applications environnementales." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22475/document.
Full textAbstract:
Ce travail décrit la synthèse et le comportement de nouveaux photocatalyseurs à base de dioxyde de titane utilisés pour des applications environnementales. Dans la première partie, la pertinence des composés modèles testés, le colorant acide orange 7 (AO7) et le 4-Chlorophénol (4-CP), pour des traitements photocatalytiques à base de TiO2 a été étudiée et validée. Cette étude a été centrée sur l’effet de la concentration initiale en composé et sur la vitesse d’agitation pendant la réaction photocatalytique. La deuxième partie est consacrée principalement à la synthèse et la caractérisation des suspensions de particules colloïdales de TiO2. Leur séparation puis leur récupération après le traitement étant pratiquement impossible l’immobilisation de ces particules sur des supports de type hydroxydes doubles lamellaires (HDL) a été étudiée afin de préparer un matériau composite TiO2/HDL présentant une activité photocatalytique comparable à celle du dioxyde de titane pur. Un deuxième type de composite basé sur des mélanges de TiO2/SiO2 a également été envisagé et utilisé dans la préparation de fines couches efficaces pour la photodégradation de l’hexane. Enfin, le comportement photocatalytique d’HDL pur à base de zinc et de chrome, sans addition de TiO2, a également été étudié et est présenté dans la partie finale de cette thèse. Les matériaux préparés ont été caractérisés par différentes analyses chimiques, diffraction et fluorescence des rayons X, microscopie électronique à transmission et à balayage, spectroscopie IR à transformé de Fourier, analyse thermogravimétrique, mesure du potentiel Zeta, diffusion de la lumière, mesure d’adsorption N2. Les différents matériaux ont été testés photocatalytiquement via la photo-Oxydation en solution aqueuse de l’acide orange 7 (AO7), du 4-Chlorophénol (4-CP) ou du bleu de méthylène à différents pH. L’activité photocatalytique du matériau composite à base de TiO2/SiO2 sous forme de film fin a été évaluée en phase gaz en présence d’hexaneThis work describes the behaviour and fabrication of new photocatalysts based on titaniumdioxide for the purpose of environmental applications. It consists of five closely connectedparts. In the first part the suitability of chosen model compounds, azo dye Acid Orange 7(AO7) and 4-Chlorophenol (4-CP), for photocatalytic activity assessment of TiO2 was studied.This study was focused on the effect of different initial concentrations of model compoundand different rates of stirring during photocatalytic reaction. The second part then focusedmainly on the synthesis and characterization of aqueous colloidal suspensions of TiO2. Theseparation of TiO2 particles in the form of colloidal suspensions and their regeneration afterthe reaction, while keeping the same photocatalytic properties, is almost not possible.Therefore, it was necessary to find an appropriate method how to immobilize these particleson the support or in the form of composite. The layered double hydroxides (LDH) werechosen as one of suitable supports for TiO2 photocatalyst. The focus was kept on thepreparation of TiO2/LDH composites with the same or higher photocatalytic activity as purecolloidal titanium dioxide. The second chosen type of composite was based on twocomponentTiO2/SiO2 material and these composites were used for the preparation of thinlayers. Photocatalytic behaviour of pure LDHs and their possible use as photocatalyst withoutTiO2 addition was also studied and described in a final part of this work. Prepared materials were characterized by chemical analysis, X-Ray diffraction andflorescence, transmition electron microscopy, scanning electron microscopy, Fouriertransform infrared spectroscopy, thermogravimetric analysis, dynamic light scattering, zetapotential measurement and N2 adsorption. As another step, materials were tested asphotocatalyst by the photooxidation of Acid Orange 7, 4-Chlorophenol and Methylene Blue indifferent pH in aqueous medium. Photocatalytic activity of TiO2/SiO2 composites in the formof thin films was tested in gaseous phase using hexane as a model pollutant. It was found that quantum yields of 4-CP degradation for all prepared alkaline colloidalsuspensions of TiO2 were lower than those obtained for acidic TiO2 colloidal suspensions. Inthe contrary to the quantum yield of acidic TiO2, the quantum yield of alkaline suspensionsdecreased during the aging. Prepared TiO2/Mg2Al1.5 nanocomposites exhibited higherphotocatalytic activity than the original TiO2 in basic conditions and also it was much easierto recover the photocatalyst after reaction by simple sedimentation. In the case of TiO2/SiO2composites, it was found that composite prepared with TiO2:SiO2 ratio 1:1 has higherphotocatalytic activity in aqueous media than starting pure TiO2 but with increasing SiO2content reaction rate of AO7 degradation decreases. Thin layers of TiO2:SiO2 compositeprepared from simultaneously co-Precipitated particles (they have improved crystallinity inrelation to pure TiO2) are able to photocatalyticaly degrade hexane. In the case of pure LDH,it was proved that even noncalcined Zn2CrCO3 LDH can produce HO• radicals. However,mixed oxides (containing ZnO) prepared by LDH calcination at temperatures higher than500°C, showed higher efficiency
37
Orlowski, Jessica Marie. "Ties That Bind." Digital Archive @ GSU, 2010. http://digitalarchive.gsu.edu/art_design_theses/60.
Full textAbstract:
I am fascinated by the inner thoughts, the memories, and the cumulative experience that make us each a complex physiological puzzle. From birth, sociological building blocks are constructed forming emotional walls and unexpected doorways, boundaries and comfortable passageways through the architecture of our personalities. My thesis work, which is comprised of ceramic figures and interactive toys, offers playful memory triggers and evocative spaces in which viewers can deconstruct the building blocks of their social persona.
38
Hagenbeek, A. "Machten van tien." [S.l.] : Rotterdam : [de auteur] ; Erasmus University [Host], 1994. http://hdl.handle.net/1765/7471.
Full text
39
Mousinho, George Alexandre Ayres de Menezes. "Subversive blood ties." reponame:Repositório Institucional da UFSC, 2013. http://repositorio.ufsc.br/handle/123456789/103567.
Full textAbstract:
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Letras/Inglês e Literatura Correspondente, Florianópolis, 2013Made available in DSpace on 2013-07-16T21:16:13Z (GMT). No. of bitstreams: 1 316413.pdf: 3118322 bytes, checksum: 8dc028ee0e2a57f76f712d62530548e0 (MD5)
Esta dissertação consiste em investigar a construção do tema da decadência Gótica em Drácula de Bram Stoker e duas adaptações fílmicas do romance - Nosferatu, de Friedrich Wilhelm Murnau, e Drácula de Bram Stoker, de Francis Ford Coppola - tendo como centro da análise como três personagens - Drácula, Jonathan Harker e Mina Harker - se relacionam com tal tema. A decadência Gótica é um padrão literário do contexto fin-de-siècle da sociedade vitoriana inspirada pela crise social que acontecia na Inglaterra no fim do século XIX (Punter e Byron 39-40). Autores como Bram Stoker escreveram histórias que refletiam medos morais e sociais da sociedade vitoriana, retratando imagens de monstros que representavam a transgressão de fronteiras morais e sexuais estabelecidas pelas tradições vitorianas (Botting 88). Tendo tal discussão em mente, este estudo busca conectar a retratação de tal tema do romance às adaptações, também utilizando uma análise fílmica para identificar técnicas que destacam a representação do tema relacionado aos três personagens, finalmente ligando tal tema a crises e confusões sociais que aconteciam nos contextos de ambos os filmes.
Abstract : The present dissertation consists of an investigation of the construction of the Gothic theme of decadence in Bram Stoker's Dracula and two film adaptations of the novel - Friedrich Wilhelm Murnau's Nosferatu and Francis Ford Coppola's Bram Stoker's Dracula - having as the centre of analysis how three characters - Dracula, Jonathan Harker and Mina Harker - relate to that theme. The Gothic decadence is a literary motif from the fin-de-siècle context of the Victorian Era inspired by the social crisis that took place in England in the late nineteenth century (Punter and Byron 39-40). Authors like Bram Stoker wrote stories that reflected moral and social fears of the Victorian society, depicting images of monsters that represented the crossing of moral and sexual boundaries established by the Victorian traditions (Botting 88). Bearing that discussion in mind, this study aims at connecting the portrayal of such a theme from novel to the two adaptations, also making use of a filmic analysis to identify techniques that highlight the depiction of the theme related to the three characters, ultimately linking such a thematic depiction to crises and social commotions that were taking place in both films' social contexts.
40
Tshisela, Namhla. "Ties that bind." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/5913.
Full textAbstract:
This collection of short stories about contemporary black South African women reveals their hopes and anxieties, and explores their relationships with themselves, their families, and the people around them. It sets out to challenge stereotypes about black women being browbeaten in a country riddled by poverty and disease by portraying women successfully forging their identities in society.
41
Chen, Xiaobo. "Synthesis and Investigation of Novel Nanomaterials for Improved Photocatalysis." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1117575871.
Full text
42
Ishchenko, Olga. "Elaboration of plasmonic nano-composites and study of their specific catalytic activities." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF042/document.
Full textAbstract:
L’objective est d’améliorer l’activité photocatalytique de TiO2 sous irradiations UV et Visible. Pour contourner les limites de TiO2 intrinsèque nous envisageons une fabrication de nanocomposite plasmonique à base de nanofils de TiO2 périodiquement organisés et assemblés avec des nanoparticules plasmoniques. Pour la fabrication des nanofils de TiO2 mécaniquement stables, deux approches ont été réalisées. La première approche est basée sur la croissance sélective en phase vapeur, la deuxième approche consiste en l’utilisation d’un moule de membranes AAO et d’un dépôt de films conformes par ALD. En parallèle les films de TiO2déposés par ALD sont assemblés avec les nanoparticules plasmoniques d’or. Les différentes architectures de TiO2 sont valorisées par des tests photocatalytiques (UV et Visible) sur les polluants modèles. Une nouvelle approche de la fabrication des films mesoporeux d’H-TiO2 avec efficacité photocatalytique à la fois sous irradiation UV et Visible est développéeThe objective of this thesis is to improve the photo-response of well-known photocatalytic material such as TiO2, which is usually only active in the UV range. The basic idea is to assemble several approaches within one device to improve the photocatalytic properties: fabrication of periodically-organised TiO2 nanostructures and their assembly with plasmonic nanoparticles. Two fabrication strategies were investigated for these purposes. The first approach consists of selective vapour phase growth. The second approach implements the use of an AAO template. In parallel, TiO2 films deposited by ALD and assembled with plasmonic gold nanoparticles are investigated. The photocatalytic measurements on various TiO2 architectures were performed in both irradiation ranges UV and Vis. A new fabrication approach of mesoporous H-TiO2 films was developed giving promising results of photocatalytic efficiency improvement in both UV and Visible ranges
43
Persson, Oscar, and Viktor Kihlblom. "Ensuring Sustainability Beyond Tier-One : The Issue of Second-Tier Suppliers." Thesis, Internationella Handelshögskolan, Högskolan i Jönköping, IHH, Företagsekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-30210.
Full textAbstract:
Background: Exposure of non-sustainable practices put MNCs in bad light, hurting their brand image. Therefore, it is of great importance to ensure supplier sustainability upwards the chain. Vast focus has been put on the first-tier suppliers. However, there are few studies that have investigated the issue of second-tier supplier sustainability, and there are many real life examples of firms’ who failed to ensure second-tier supplier sustainability. Hence, the need for further investigation within the subject. Purpose: The purpose of this study was to investigate how two Scandinavian-based MNCs ensure second-tier supplier sustainability within their supply chain. Methodology: This thesis is conducted with an inductive approach, collecting qualitative data through semi-structured interviews and archival research, at two independent companies. Thus, a multiple case study. Empirical findings were analyzed through a template analysis. Based on the theoretical framework and formulated research questions, categories have been derived, constructing the outline for our empirical findings and analysis. Conclusions: (I) Social and cultural distance are major determinants settling which second-tier suppliers being regarded as critical. Conclusively, these two factors are the major determinants identifying whom to prioritize. Furthermore, IT is recognized as a vital and beneficial tool to utilize when mapping the network of second-tier suppliers. (II) In order to achieve second-tier supplier compliance of CoC, “the grey area approach” is identified as the used approach by investigated companies. Further, long-term relationships with first-tier suppliers are a major key in order to ensure second-tier sustainability in long-term perspective. (III) Last but not least, first-tier supplier network investigation is regarded prior to choosing a first-tier supplier. However, it is nothing decisive since other factors are more important in the process.
44
Vesna, Despotović. "Fotolitička i fotokatalitička razgradnja odabranih herbicida u vodenoj sredini." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2014. https://www.cris.uns.ac.rs/record.jsf?recordId=86616&source=NDLTD&language=en.
Full textAbstract:
Ispitana je kinetika i mehanizam fotokatalitičke razgradnje herbicida kvinmeraka i klomazona u prisustvu UV/TiO2 Degussa P25, odnosno piklorama i klopiralida primenom UV/TiO2 Wackherr pri različitim eksperimentalnim uslovima. Praćena je i kinetika razgradnje odabranih herbicida direktnom fotolizom uz primenu sunčevog, UV i vidljivog zračenja, kao i u odsustvu svetlosti. Pored toga, upoređena je efikasnost UV/TiO2 Degussa P25, odnosno UV/TiO2 Wackherr sa vidljivim zračenjem, kao i direktnom fotolizom u prisustvu pomenutih izvora svetlosti. U cilju procene citotoksičnosti klomazona i klopiralida, kao i smeše klomazona i klopiralida i njihovih intermedijera nastalih tokom fotokatalitičke razgradnje ispitan je in vitro rast ćelijskih linija MRC-5 i H-4-II-E. Nakon ispitivanja fotokatalitičke razgradnje odabranih herbicida u dvaput destilovanoj vodi, praćena je njihova razgradnja i u prirodnim vodama. Takođe, ispitan je uticaj dodatka hidrogenkarbonata i huminske kiseline na efikasnost razgradnje odabranih herbicida. Fotokatalitička razgradnja klomazona, piklorama i mekopropa je ispitivana i u prisustvu UV/TiO2 nanocevi. Aktivnost katalizatora TiO2 Wackherr i TiO2 nanocevi je upoređena sa TiO2 Degussa P25.The kinetics and mechanism of photocatalytic degradation of the herbicides quinmerac and clomazone in the presence of UV/TiO2 Degussa P25, and of picloram and clopyralid using UV/TiO2 Wackherr under different experimental conditions were studied. The kinetics of degradation of selected herbicides by direct photolysis using sunlight, UV and visible radiation, and in the absence of light were followed. In addition, the efficiencies of UV/TiO2 Degussa P25 and UV/TiO2 Wackherr were compared with visible radiation and direct photolysis in the presence of the above mentioned light sources. In order to evaluate the cytotoxicity of clomazone and clopyralid alone and in their mixture with intermediates formed during the photocatalytic degradation, in vitro growth of cell lines, MRC-5 and H-4-II-E was followed. After examining the photocatalytic degradation of selected herbicides in double distilled water, their decomposition in natural waters was also followed. Also, the influence of hydrogencarbonate and humic acid addition on the efficiency of degradation of selected herbicides was studied. Photocatalytic degradations of clomazone, picloram and mecoprop were investigated in the presence of UV/TiO2 nanotubes. Activities of the catalysts TiO2 Wackherr and TiO2 nanotubes were compared to TiO2 Degussa P25.
45
Carriel, Rodrigo Crociati. "Caracterização de filmes finos de TiO2 obtidos por deposição química em fase vapor." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-02042015-101635/.
Full textAbstract:
Filmes finos de TiO2 foram crescidos sobre silício (100) através do processo de deposição química de organometálicos em fase vapor (MOCVD). Os filmes foram crescidos a 400, 500, 600 e 700ºC em um equipamento horizontal tradicional. Tetraisopropóxido de titânio foi utilizado como fonte tanto de titânio como de oxigênio. Nitrogênio foi utilizado como gás de arraste e como gás de purga. Foram realizadas análises de difração de raios-x para a caracterização da estrutura cristalina. Microscopia eletrônica de varredura com canhão de emissão de campo foi utilizada para a avaliação da morfologia e da espessura dos filmes. Os filmes de TiO2 crescidos a 400 e a 500ºC apresentaram fase anatase. O filme crescido a 600ºC apresentou as fases anatase e rutilo, enquanto que o filme crescido a 700ºC apresentou, além de anatase e rutilo, a fase broquita. Para se avaliar o comportamento eletroquímico dos filmes foi utilizada a técnica de voltametria cíclica. Os testes indicaram um forte caráter capacitivo dos filmes de TiO2. O pico de corrente anódica é diretamente proporcional à raiz quadrada da velocidade de varredura para os filmes crescidos a 500ºC, sugerindo que o mecanismo predominante de transporte de cátions seja por difusão linear. Observou-se que o filme crescido por 60 minutos permitiu maior facilidade de intercalação e desintercalação de íons Na+. Os filmes crescidos nas demais condições não apresentaram pico de corrente anódica, embora o acúmulo de cargas se fizesse presente.Titanium dioxide (TiO2) thin films were grown on silicon substrate (100) by MOCVD process (chemical deposition of organometallic vapor phase). The films were grown at 400, 500, 600 and 700 ° C in a conventional horizontal equipment. Titanium tetraisopropoxide was used as source of both oxygen and titanium. Nitrogen was used as carrier and purge gas. X-ray diffraction technique was used for the characterization of the crystalline structure. Scanning electron microscopy with field emission gun was used to evaluate the morphology and thickness of the films. The films grown at 400 and 500°C presented anatase phase. The film grown at 600ºC presented rutile besides anatase phase, while the film grown at 700°C showed, in addition to anatase and rutile, brookite phase. In order to evaluate the electrochemical behavior of the films cyclic voltammetry technique was used. The tests revealed that the TiO2 films formed exclusively by the anatase phase exhibit strong capacitive character. The anodic current peak is directly proportional to the square root of the scanning rate for films grown at 500ºC, suggesting that linear diffusion is the predominant mechanism of cations transport. It was observed that in the film grown during 60 minutes the Na+ ions intercalate and deintercalate easily. The films grown in the other conditions did not present the anodic current peak, although charge was accumulated in the film.
46
Ghori, Muhammad Zubair [Verfasser]. "Synthesis and Functional Applications of Highly Photocatalytic TiO2 Based Surfaces: Al/TiO2 and Au/TiO2 Hybrid Structures / Muhammad Zubair Ghori." Kiel : Universitätsbibliothek Kiel, 2018. http://d-nb.info/1164443909/34.
Full text
47
Andrianainarivelo, Mahandrimanana. "Homogénéité d'oxydes mixtes SiO2-ZrO2, SiO2-TiO2, TiO2-ZrO2, Al2O3-TiO2 et Al2O3-SiO2 préparés par sol-gel non hydrolytiques." Montpellier 2, 1996. http://www.theses.fr/1996MON20077.
Full textAbstract:
Dans ce travail, nous avons prepare des oxydes mixtes: sio#2-zro#2, sio#2-tio#2, tio#2-zro#2, al#2o#3-tio#2 et al#2o#3-sio#2 par un procede sol-gel non hydrolytique base sur la condensation des chlorures metalliques et les alcoxydes metalliques ou entre des chlorures metalliques et des donneurs d'oxygene tels que les ethers. Les rendements en oxydes obtenus apres elimination des groupements organiques residuels sont eleves. Edx et icp nous ont permis de montrer que la composition des oxydes finaux dependait directement de la stoechiometrie des precurseurs. L'homogeneite des gels a ete determinee par leur comportement a la cristallisation et par rmn du #2#9si et ir. Les gels bicomposants obtenus par la voie sol-gel non hydrolytique sont homogenes sauf lorsque le taux de titane est superieur a 8. 5% dans le systeme sio#2/tio#2
48
Duan, Aoshu. "Preparation and Characterization of TiO2-Based Nano Particles and Tests for Their Activities in Meth¬ylene Blue Photodegradation." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31378.
Full textAbstract:
A two-step hydrothermal method was applied to synthesis Vanadium Sulfide (IV) coupled with commercial P25 on TiO2 nanoparticle (VS4-on-P25). Materials were characterized by scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV-Vis), diffuse reflectance UV-Vis spectroscopy and Raman spectroscopy. Photocatalytic activity of this new material was determined by photo-degradation of Methylene blue (MB) under UV irradiation. Experiments show that the VS4-on-P25 exhibits a higher photocatalytic activity than commercial P25 by providing more active site for dye adsorption, and reducing the recombination of charge carriers. Furthermore, the VS4-on-P25 extends its light-absorption spectrum into visible-light range due to its narrower band gap. The highest photocatalytic activity was found with a VS4 loading of 6 wt.%, which outperforms pure P25 by a factor of 2.29 in MB degradation rate.
49
POUILLEAU, JEROME. "Proprietes electrochimiques des systemes ti/tio2/electrolyte et ti/tio2/metal/electrolyte." Paris 6, 1996. http://www.theses.fr/1996PA066341.
Full textAbstract:
Dans la premiere partie de cet ouvrage, sont etudies les transferts electroniques pour les systemes ti/tio2/electrolyte. La vitesse de reaction de transfert de charge a l'interface est liee a l'epaisseur de la couche d'oxyde. Le comportement semiconducteur de type (n) des oxydes de titane permet d'utiliser les structures ti/tio2 pour des reactions cathodiques. La modification des structures par un depot de platine modifie considerablement la cinetique du transfert electronique avec un couple redox en solution. Cette cinetique est etudiee dans la seconde partie par spectroscopie d'impedance. Pour les deux systemes etudies, un processus de transfert electronique par effet tunnel via des etats intermediaires est propose. La derniere partie du memoire regroupe les resultats des analyses physico-chimiques (esca, rbs, diffraction des rayons x, afm, meb) qui ont ete employees pour caracteriser les interfaces (epaisseur et composition des couches,)
50
Ullah, Sajjad. "Materiais nanoestruturados e filmes finos baseados em TiO2 para aplicação em fotocatálise." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/75/75135/tde-26012015-173233/.
Full textAbstract:
O objetivo desta Tese é preparar e caracterizar nanopartículas de TiO2 e SiO2@ TiO2 e obter filmes finos baseados nesses materiais nanoestruturados usando a metodologia de preparação de filmes conhecida como layer-by-layer (LbL). Primeiramente, TiO2 amorfo sintetizado a partir de sulfato de titanila (TiOSO4) foi cristalizado por método de tratamento hidrotérmico brando (HTT). O efeito da temperatura e tempo de tratamento hidrotérmico na cristalinidade, tamanho de partícula e fotoatividade de TiO2 foi estudado. A análise de MET, DRX e área de superfície confirmou que o HTT a temperatura tão baixa quanto 105°C pode ser utilizada para obter as nanopartículas de anatase com boa cristalinidade (~95%), pequeno tamanho de cristalito (<10 nm), alta área de superfície (>200 m2.g-1) e excelente seletividade da fase. Em uma segunda etapa do projeto, o nanocatalisador de TiO2 foi depositado, via rota sol-gel, na superfície de NPs de sílica Stöber (diâmetro 200 nm), formando um sistema core@shell (SiO2@ TiO2). O objetivo desse processo foi de se obter melhor estabilidade térmica (1000°C), boa dispersão e menor aglomeração do nanocatalisador (TiO2). As análises de microscopia eletrônica (MEV e MET) confirmaram a formação de uma camada porosa (espessura 10-30 nm) de TiO2 formadas por cristalitos com cerca de 5 nm. Um estudo das propriedades ópticas das amostras SiO2@ TiO2 mostrou que o deslocamento no onset de absorção é função do espalhamento Rayleigh. Finalmente, desenvolveu-se um novo e versátil procedimento LbL para a preparação de filmes multicamadas, porosos e uniformes de TiO2 empregando fosfato de celulose (CP) como polieletrólito eficiente e não convencional. A formação dos filmes (CP/ TiO2 e CP/ TiO2/HPW) foi monitorada por espectroscopia UV/Vis e a interação entre os componentes dos filmes (CP, TiO2 e HPW) foi estudada pelas técnicas MET, XPS e FTIR. Estes filmes LbL apresentaram boa fotoatividade para degradação de ácido esteárico, cristal violeta e azul de metileno sobre irradiação UV. Os filmes CP/HPW formados em celulose bacteriana apresentaram boa resposta fotocrômica, que é aumentada pela presença do TiO2 devido a uma transferência eletrônica interfacial do TiO2 para o HPW. A interface entre nanopartículas de titânia e nanopartículas de ácido fosfotungstico foi pela primeira vez caracterizada por Microscopia Eletrônica de Transmissão como sendo não-cristalina. Este método simples e ambientalmente amigável pode ser utilizado para formar recobrimentos em uma grande variedade de superfícies com filmes fotoativos de TiO2 e TiO2/HPW.The aim of the present investigation was to prepare and characterize TiO2 and core@shell (SiO2@TiO2) nanoparticles (CSNs) and form layer-by-layer (LbL) films with these nanoparticles (NPs) on various substrates. Firstly, amorphous TiO2 were prepared from oxotitanium (IV) sulfate (TiOSO4) and crystallized by low-temperature hydrothermal treatment (HTT). The effect of hydrothermal temperature and treatment time on crystallinity, particle size and photoactivity of TiO2 was studied. The TEM, XRD and BET surface area analysis confirmed that HTT at temperature as low as 105°C can be used to obtain phase-pure anatase nanoparticles with good crystallinity (~95%), small crystallite size (<10 nm), high surface area (>200 m2.g-1) and excellent phase selectivity. Secondly, TiO2 nanocatalyst was directly deposited, via sol-gel route, on the surface of Stöber silica NPs of around 200 nm in a core@shell (SiO2@ TiO2) configuration to obtain better thermal stability, good dispersion and less agglomeration of the nanocatalyst. SEM and TEM observation confirmed the formation of a porous anatase shell of crystalline TiO2 consisting of around 5-8 nm small crystallites, in accordance with XRD results. The shell thickness was varied between 10-30 nm by varying the quantity of precursor titanium (IV) isopropoxide (TiP). Compared to the uncoated silica, the BET surface area also increased by 147-365% depending on the amount of TiP added during synthesis step. The effect of shell morphology and TiO2 loading on surface area and photoactivity has been studied and compared among different CSNs. Finally, a new and versatile LbL procedure for the preparation of porous and highly dispersed multilayer films of TiO2 and phosphotungstic acid (HPW) on different substrates was developed using Cellulose Phosphate (CP) as an efficient and non-conventional binder. The films formation was monitored by UV/Vis spectroscopy and the interaction between the films components (CP, TiO2 and HPW) was studied by HRTEM, XPS and FTIR techniques. These CP/ TiO2 and CP/ TiO2/HPW LbL films showed good photoactivity against stearic acid (SA), crystal violet (CV) and methylene blue (MB) under UV irradiation. The CP/HPW films formed on bacterial cellulose showed good photochromic response, which is enhanced in presence of TiO2 due to an interfacial electron transfer from TiO2 to HPW. This simple and environmentally safe method can be used to form coatings on a variety of surfaces with photoactive TiO2 and TiO2/HPW films.