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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Uroguanylin : molecular cloning and characterization of a potential natriuretic hormone /

Fan, Xiaohui, January 1997 (has links)
Thesis (Ph. D.)--University of Missouri--Columbia, 1997. / "May 1997" Typescript. Vita. Includes bibliographical references (l. 117-131). Also available on the Internet.
52

Pica and peptides : assessing gastrointestinal malaise /

Madden, Lisa J., January 1998 (has links)
Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [42]-50).
53

Integration of POL II transcription with pre-MRNA processing on human genes /

Glover-Cutter, Kira Marina. January 2008 (has links)
Thesis (Ph.D. in Molecular Biology) -- University of Colorado Denver, 2008. / Typescript. Includes bibliographical references (leaves 185-214). Free to UCD Anschutz Medical Campus. Online version available via ProQuest Digital Dissertations;
54

A study of the expression of Sonic hedgehog and its receptors in T cells and the identification of Sonic hedgehog dowm-stream targets in activated CD4+T cells

Chau, Suk-yi. January 2004 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.
55

Exploring the roles of the RNA Polymerase II CTD in pre-MRNA metabolism /

Bird, Gregory A. January 2005 (has links)
Thesis (Ph.D. in Molecular Biology) -- University of Colorado at Denver and Health Sciences Center, 2005. / Typescript. Includes bibliographical references (leaves 130-152). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;
56

Mononuclear and multinuclear salicylaldimine metal complexes as catalysts precursors in the oxidation of phenol and cyclohexene

Van Wyk, Juanita Lizélle January 2009 (has links)
Philosophiae Doctor - PhD / In this thesis typical homogeneous and dendritic immobilized catalysts derived from salicylaldimines were investigated as catalysts for the oxidation of hydrocarbons using hydrogen peroxide as oxidant under aerobic conditions. This research work thus describes the synthesis of several new N-(aryl)salicylaldimines as well as peripheral functionalised salicylaldimine poly(propyleneimine) dendrimers. The dendritic ligands were obtained by modifying the peripheral groups of Generation 1 and Generation 2 poly(propyleneimine) dendrimer, (DAB-(NH2)n) which are commercially available. Both types of ligands were utilized to synthesize Cu(II) and Co(II) complexes using appropriate acetate salts. The ligands systems and metal complexes prepared were fully characterized using a range of physical techniques. The Cu(II) and Co(II) complexes were evaluated as catalysts for the oxidation of phenol and cyclohexene using hydrogen peroxide as oxidant under an oxygen atmosphere. The catalytic oxidation of phenol to the dihydroxybenzenes, catechol (CT) and hydroquinone (HQ), was investigated in aqueous media at various pH values. All the complexes investigated were active for the hydroxylation process producing CT as major product. The pH of the reaction medium was found to have much more of an influence on the activity and product selectivity of the Co(II) complexes as compared to the case for the Cu(II) complexes. All the catalysts investigated were also found to exhibit good activity for the oxidation of cyclohexene producing predominantly the allylic oxidation products 2-cyclohexene-1-one and 2-cyclohexene-1-ol. However the formation of the epoxide, cyclohexene oxide was also observed as minor product or in trace quantities. It was found that the cobalt catalysts produced 2-cyclohexene-1-one as major product, however higher levels of 2-cyclohexene- 1-ol was produced by all catalysts in catalytic runs where the oxidant to substrate ratio was reduced and when the metal loading was increased. In the case of the copper catalysts 2- cyclohexene-1-ol was produce in slightly higher levels than 2-cyclohexene-1-one.
57

Synthesis and characterisation of metal chalcogenide thin films

Pearce, Amber Marie January 2014 (has links)
There is much interest in the electronic potential of ‘nano’-semiconductors. The avenue of research pursued in this project was in inorganic analogues of graphene, namely metal chalcogenides MxEy (M = metal, E = S, Se, Te, x ≠ y = integer value). Thin films of these materials have been used in solar cells, ambient thermoelectric generators and IR detectors, due to their interesting properties, such as: optoelectronics, magnetooptic, piezoelectric, thermoelectric and photovoltaic, as well as electrical conductivity. The key issues with the use of these materials are the formation of controlled films, especially in terms of stoichiometry, crystallinity and uniformity, and also the precursor system used. The aim of this research was to synthesise and isolate novel precursor compounds for use in the deposition of metal sulfide thin films (for use with molybdenum and tungsten). The potential viability of the compounds as single source precursors (ssp) was judged following ThermoGravimetric Analysis (TGA). The compounds were also subjected to analysis using NMR (1H, 13C and 31P where applicable), infrared and UV-Vis spectroscopy, as well as elemental analysis. Cadmium sulfide (CdS) is one of the key direct band gap II-VI semiconductors, having vital optoelectronic applications for laser light-emitting diodes, and optical devices based on non-linear properties. The ratio of these films should ideally be 1:1, however, during the formation of cadmium sulfide films, particularly at elevated temperatures, a common problem encountered is the production of sulfur deficient films. These films have a formula consistent with 〖Cd〗_x S_y, where x is an integer value greater than y, but the sulfur deficiency is generally no greater than 10 %. In order to correct this sulfur deficiency, it was decided to investigate deposition making use of both a ssp and an additional sulfur source, with the aim of producing uniform films with 1:1 Cd:S.Molybdenum disulfide films have been deposited previously from multi source precursors and more recently using ssp. In this project MoS2 was deposited using novel ssps in both LP and AACVD on a variety of substrates with the aim of producing uniform thin films and assessing any differences in the morphology of the deposition. This work was continued with the deposition of WS2 and MoxW1-xS2 from ssps which had not been reported previously. The films deposited were analysed using XRD, SEM, EDX (when available) and Raman spectroscopy.
58

New molecular precursors for metal sulfides

Ramasamy, Karthik January 2010 (has links)
Metal sulfide thin films are important class of materials which have applications in photovoltaics, microelectronics and displays. Chemical vapour deposition (CVD) is well known method for the deposition of high quality thin films. Very few classes of single source precursors (eg: dithiocarbamates, xanthates) were successful for the deposition of good quality metal sulfide films by MOCVD. This limited choice was due to the difficulties of finding precursors with suitable physico-chemical properties. Hence, it is important to develop precursors with suitable volatility, solubility and being able to deposit films with little or no contamination. This work describes the synthesis of a series of metal (Fe, Co, Ni, Zn, Cd) complexes of thio- and dithio-biuret ligands, their structural and spectroscopic characterization and thermal decomposition. The complexes were used as single source precursors for the deposition of iron, cobalt, nickel, zinc, cadmium and zinc cadmium sulfide thin films by AACVD. The effect of alkyl groups, coordinating atoms, deposition temperatures on phases and morphology of the films were studied. The deposited films were characterised by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and atomic force microscopy (AFM). The complex [Fe(SON(CNiPr2)2)3] gave hexagonal troilite FeS films with small amount of tetragonal pyrrhotites Fe1-xS at 300 °C, whereas only troilite FeS was deposited at 350, 400 or 450 °C. Complexes [Fe2(µ-OMe)2 (SON(CNEt2)2)2] and [Fe(SON(CNEt2)2)3] deposited a mixture of hexagonal troilite FeS and cubic pyrite FeS2 films at all temperatures. [Fe(SON(CNMe2)2)3] deposited very thin films of FeS at all temperatures as troilite. Complexes [Co(N(SCNMe2)2)3] and [Co(N(SCNEt2)2)3] deposited hexagonal Co1-xS films at all temperatures of 350-500 °C, whereas [Co(SON(CNiPr2)2)2] gave mixture of cubic and hexagonal Co4S3 films at 280-400 °C. Thiobiuret complex [Ni(SON(CNMe2)2)2] gave orthorhombic Ni7S6. Complexes [Ni(SON(CNMe2CNEt2))2] and [Ni(SON(CNEt2)2)2] gave mixtures of hexagonal Ni17S18 and orthorhombic Ni7S6. In contrast, [Ni(SON(CNiPr2)2)2] gave orthorhombic Ni9S8. Dithiobiuret complexes [Ni(N(SCNMe2SCNEt2))2] and [Ni(N(SCNEt2)2)2] gave hexagonal NiS1.03 at 360 and 400 °C, orthorhombic Ni7S6 phase at 440 and 480 °C. The zinc complexes [Zn(N(SCNMe2)2)2] and [Zn(SON(CNiPr2)2)2] deposited cubic ZnS at 300 and 350 °C, whereas at 400 and 450 °C hexagonal ZnS were apparent [Zn(N(SCNEt2)2)2] gave hexagonal ZnS films at all deposition temperatures. Cadmium complexes [Cd(N(SCNMe2)2)2], [Cd(N(SCNEt2)2)2] and [Cd(SON(CNiPr2)2)2] gave hexagonal CdS films at all deposition temperatures.
59

Bone phenotype of lysyl oxidase isoform knockout mice & in vitro expression of lysyl oxidase proenzyme

Alsofi, Loai A. January 2008 (has links)
Thesis (D.Sc.D.)--Boston University, Goldman School of Dental Medicine, 2008 (Dept. of Periodontology and Oral Biology). / Includes bibliographical references: leaves 140-148. / Lysyl oxidases constitute a family of enzymes responsible for the formation of cross links in collagen and elastin. These enzymes have also been linked to pathological fibrosis. The importance of collagen in the structural and mechanical properties of bone led us to investigate the hypothesis that the absence of one or more of these enzymes could lead to a significant bone phenotype. This phenotype could resemble osteoporosis or diabetic bone disease. In addition, we tried to overexpress lysyl oxidase proenzyme in vitro. The ability to produce enough amounts of lysyl oxidase proenzyme and the ability to process it and activate it could facilitate the development of drugs that control its activity in pathological fibrosis. Bones from 12-week old mice (8 males and 8 females) with the compound genotype LOX+/-, LOXLl -/- were analyzed. 5 males of the genotype LOX+/+, LOXLl-/were also analyzed. 16 wild type mice (8 males and 8 females) were used as controls. μCT was used to analyze the trabecular and cortical bone morphology of both left femur and L5 vertebrae (n=5). The femora were subsequently subjected to mechanical testing using the twist failure in torsion. Right femurs (n=5) were used for histology and histromorphometric analysis. Tibia and fibula (n=5) were used for cross-link analysis. Two way factor ANOV A with post-hoc Tukey HSD test was used for statistical analysis. A P value of less than 0.05 was used to declare significance. μCT analysis of the trabecular bone in femur distal ... [TRUNCATED]
60

Direct synthesis of magnetic bimetallic alloy nanoparticles from organometallic precursors and their applications

Meng, Zhengong 09 May 2016 (has links)
1.1\xMagnetic nanoparticles (NPs) with sizes ranging from 2 to 20 nm in diameter represent an important class of artificial nanostructured materials, since the NP size is comparable to the size of a magnetic domain. They have potential applications in data storage, catalysis, permanent magnetic nanocomposites, and biomedicine.;1.2\xTo begin with, a brief overview on the background of Fe-based bimetallic NPs and their applications for data-storage and catalysis was presented in Chapter 1.;1.3\xIn Chapter 2, L10-ordered FePt NPs with high coercivity were directly prepared from a novel bimetallic acetylenic alternating copolymer P3 by a one-step pyrolysis method without post-thermal annealing. The chemical ordering, morphology and magnetic properties were studied. Magnetic measurements showed that a record coercivity of 3.6 T (1 T = 10 kOe) was obtained in FePt NPs. By comparison of the resultant FePt NPs synthesized under Ar and Ar/H2, the characterization proved that the incorporation of H2 would affect the nucleation and promote the growth of FePt NPs. The L10 FePt NPs were also successfully patterned on Si substrate by nanoimprinting lihthography (NIL). The highly ordered ferromagnetic arrays on a desired substrate for bit-patterned media (BPM) were studied and promised bright prospects for the progress of data-storage.;1.4\xFuthermore, we also reported a new FePt-containing metallopolymer P4 as the single-source precursor for metal alloy NPs synthesis, where the metal fractions were on the side chain and the ratio could be easily controlled. This polymer was synthesized from random copolymer poly(styrene-4-ethynylstyrene) PES-PS and bimetallic precursor TPy-FePt ([Pt(4-ferrocenyl-(NN̂N̂))Cl]Cl) by Sonogashira coupling reaction. After pyrolysis of P4, the stoichiometry of Fe and Pt atoms in the synthesized NPs (NPs) is nearly close to 1:1, which is more precise than using TPy-FePt as precursor. Polymer P4 was also more favorable for patterning by high throughout NIL as compared to TPy-FePt. Ferromagnetic nanolines, potentially as bit-patterned magnetic recording media, were successfully fabricated from P4 and fully characterized.;1.6\xBesides, a bimetallic complex TPy-FePd-2 was prepared and used as a single-source precursor to synthesize ferromagnetic FePd NPs by one-pot pyrolysis. The resultant FePd NPs have a mean size of 19.8 nm and show the coercivity of 1.02 kOe. In addition, the functional group (-NCMe) in TPy-FePd-2 was easily substituted by a pyridyl group. A random copolymer PS-P4VP was used to coordinate with TPy-FePd-2, and the as-synthesized polymer made the metal fraction disperse evenly along the flexible chain. Fabrication of FePd NPs from the polymers was also investigated, and the size could be easily controlled by tuning the metal fraction in polymer. FePd NPs with the mean size of 10.9, 14.2 and 17.9 nm were prepared from the metallopolymer with 5 wt%, 10 wt% and 20wt% of metal fractions, respectively.;1.7\xIn Chapter 4, molybdenum disulfide (MoS2) monolayers decorated with ferromagnetic FeCo NPs on the edges were synthesized through a one-step pyrolysis of precursor molecules in an argon atmosphere. The FeCo precursor was spin coated on the MoS2 monolayer grown on Si/SiO2 substrate. Highly-ordered body-centered cubic (bcc) FeCo NPs were revealed under optimized pyrolysis conditions, possessing coercivity up to 1000 Oe at room temperature. The FeCo NPs were well-positioned along the edge sites of MoS2 monolayers. The vibration modes of Mo and S atoms were confined after FeCo NPs decoration, as characterized by Raman shift spectroscopy. These MoS2 monolayers decorated with ferromagnetic FeCo NPs can be used for novel catalytic materials with magnetic recycling capabilities. The sizes of NPs grown on MoS2 monolayers are more uniform than from other preparation routines. Finally, the optimized pyrolysis temperature and conditions provide receipts for decorating related noble catalytic materials.;1.8\xFinally, Chapters 5 and 6 present the concluding remarks and the experimental details of the work described in Chapters 2-4.

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