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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.
1

Spatial localisation of '3'1P NMR spectroscopy in human and animal tissue in vivo

Blackledge, M. J. January 1987 (has links)
No description available.
2

Terahertz nonlinear optical response of armchair graphene nanoribbons

Wang, Yichao 01 August 2016 (has links)
It has become increasingly apparent that the future of next generation of electronic devices can and will rely on graphene nanoribbons. Graphene nanoribbons and sister structures showcase several key properties that can address the emerging need of terahertz science and technology, and break through the many technological limits on conventional semiconductor electronics operating in the terahertz spectrum. In this thesis, we focus on the study of the terahertz nonlinear optical response of metallic armchair graphene nanoribbons and sister structures using a k.p model and time dependent perturbation theory. We find that these nanoribbons exhibit a stronger interband optical response, and a smaller critical field strength (of the order of 10 kV/m) than does 2D single layer graphene. We demonstrate that finite ribbon size, spatial profile of the applied terahertz radiation field, polarization of the applied terahertz radiation, a small band gap opening, and application of a superlattice potential are several ways to tune the strong terahertz nonlinear optical response of metallic armchair graphene nanoribbons. The major contributions of this thesis include: 1) developes of a simpler method compared to other sophisticated methods of the terahertz nonlinear optical interband response of metallic armchair graphene nanoribbons; 2) extends the method in the characterization of various quantum size effects, elliptically polarized radiation field, small gap opening and superlattice on the terahertz optical response of these nanoribbons; 3) The versatility of the tunability showed in the terahertz nonlinear response of metallic armchair nanoribbons and sister structures will help advance the development of the nonlinear terahertz armchair graphene nanoribbon opto-electronic and photonic technology.
3

Técnicas avançadas para caracterização de processos de transporte dependente do Spin

Nunes Neto, Oswaldo [UNESP] 20 March 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:30:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-03-20Bitstream added on 2014-06-13T21:00:48Z : No. of bitstreams: 1 nunesneto_o_me_bauru.pdf: 1131438 bytes, checksum: 09b76ed29dfc8f7b3da8ade09c2b1487 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Efeitos de campo magnético em materiais e dispositivos orgânicos não-magnéticos vêm sendo foco de grande destaque na comunidade científica. De maneira a melhor compreender tais fenômenos, este trabalho propôs-se à implementação das técnicas de Espectroscopia de impedância elétrica em correntes alternadad (EIE-AC) na Presença de Campo Magnético e de Ressonância Magnética Detectada Eletricamente (RMDE). Para a montagem dessas técnicas foram utilizados instrumentos convencionais disponiveis no laboratório e as suas arquiteturas foram planejadas para permitir a utilização desses instrumentos em outros sistemas de medida. Programas na plataforma Agilent Vee Pro 9.2 foram desenvolvidos para o controle e aquisição dos dados das medições. A validação do sistema de EIE-AC na Presença de Campo Magnético foi efetuada a partir de medidas em circuitos básicos e num diodo orgânico emissor de luz (OLED) à base da molécula de Alq3, o qual era sabido que este apresentava o efeito de magnetoresistência. A influência do campo magnético sobre o comportamento das impedâncias do OLED de medida só foi percebida significativamente a partir da aplicação de tensões contínuas acima de 4 V, as quais condicionavam o OLED em seu estado emissivo. O fenômeno de Magneto-Impedância foi verificado nessa amostra, sendo que os efeitos mais expressivos ocorreram nas impedâncias imaginárias e para a frequencia em torno de 20Hz. Um segundo efeito de campo magnético de longo prazo de ação sobre o comportamento da impedância da amostra também foi verificado e discutido. Dentre os mecanismos físicos que podem explicar os efeitos observados no OLED, destacam-se os processos de recombinação de carga, o aprisionamento de cargas em defeitos e a ocorrência de polarização magnética das moléculas constituintes do OLED / Magnetic Field Effects on non-magnetic organic materials and device have attracted the attention of the scientific community. In order to elucidate those phenomena, this work proposes the implantation of two advanced characterization techniques: Electrical Impedance Spectroscopy in Alternating Current (EIS-AC) in the presence of magnetic field; and electrically detected magnetic resonance (EDMR). Both techniques were implemented using conventional laboratory instruments. Computational routiness were developed with Agilent Vee Pro 9.2 in order to control and acquire data from the measuring instruments. the validation f eIS-AC system was performed by using basic electrical circuits and an Organic Light Emiting Diode (OLED) based in Alq3 molecule, which has the magnetoresistance effect. The magnetic field effects over impedances were only detected when the applied continuous voltage was above 4 V, from which the OLED is in its emiting state. The Magneto-Impedance phenomenon was evidenced in this sample mainly in the imaginary impedances and for frequencies around 20 Hz. A second magnetic field effect, with long time term action over the impedance behavior, was also verified and discussed. Among the possible physical mechanisms behind the magnetic effects, charge recombination process, charge trapping by deffects, and the magnetic polarization of the OLED active molecules are discussed
4

Synthesis and Structural Characterization of New Xenon(II) Compounds and the use of an Oxidant for the Preparation of Halogenated Carbocations

Moran, Matthew D. January 2007 (has links)
<p>The chemistry of Xe(II) has been significantly extended to include the first examples of a neutral Xe(II) oxide fluoride species, O(XeF)<sub>2</sub>, as well as the first nitrate derivative of Xe(II), FXeONO<sub>2</sub>. Until recently, neutral oxide fluorides were known for all formal oxidation states of xenon except Xe(II). The synthesis of the missing oxide fluoride of Xe(II), O(XeF)<sub>2</sub>, has been accomplished by reaction of the [FXeOXeFXeF][AsF<sub>6</sub>] salt with NOF and characterized by NMR spectroscopy in CH<sub>3</sub>CN solution at -78 °C and by Raman spectroscopy. Reaction of NO<sub>2</sub>F with [FXeOXeFXeF][AsF<sub>6</sub>] has provided the first structurally characterized noble-gas nitrate, FXeONO<sub>2</sub>, which slowly decomposes (-78 °C) to XeF<sub>2</sub>·N<sub>2</sub>O<sub>4</sub>. X-ray crystal structures have been determined for FXeONO<sub>2</sub>, XeF2·N<sub>2</sub>O<sub>4</sub>, and XeF2·HNO<sub>3</sub>. The preparation of the XeONO<sub>2</sub><sup>+</sup> cation was attempted by the reaction of FXeONO<sub>2</sub> with AsF<sub>5</sub> at -78 °C, but was not directly observed. It is presumed that the cation initially forms, but rapidly decomposes to give Xe, O<sub>2</sub>, and [NO<sub>2</sub>][AsF<sub>6</sub>].</p> <p>The salt, [XeOTeF<sub>5</sub>][Sb(OTeF<sub>5</sub>)<sub>6</sub>], is a strong, low-temperature oxidant capable of oxidizing halomethanes in SO<sub>2</sub>ClF solvent at -78 °C. The CCl<sub>3</sub><sup>+</sup> and CBr3<sup>+</sup> cations have been synthesized by oxidation of CCl<sub>4</sub> and CBr<sub>4</sub>, respectively. The CBr<sub>3</sub><sub></sub><sup>+</sup> cation reacts with BrOTeF<sub>5</sub>, produced in the initial redox reaction, to give CBr(OTeF<sub>5</sub>)<sub>2</sub><sup>+</sup>, C(OTeF<sub>5</sub>)<sub>3</sub><sup>+</sup> , and Br<sub>2</sub>. The XeOTeF<sub>5</sub><sup>+</sup> cation also reacts with BrOTeF<sub>5</sub> to give the Br(OTeF<sub>5</sub>)<sub>2</sub><sup>+</sup> cation. The X-ray crystal structures of [CCl<sub>3</sub>][Sb(OTeF<sub>5</sub>)<sub>6</sub>], [CBr<sub>3</sub>][Sb(OTeF<sub>5</sub>)<sub>6</sub>]•SO<sub>2</sub>ClF, and [C(OTeF5)3][Sb(OTeF5)6]·3SO<sub>2</sub>ClF have been determined and show that the carbocations are trigonal planar about the central atom.</p> <p>Reactions of chlorofluoro-and bromofluoromethanes with [XeOTeF<sub>5</sub>][Sb(OTeF<sub>5</sub>)<sub>6</sub>] have also been investigated in SO<sub>2</sub>ClF solvent by <sup>13</sup>C and <sup>19</sup>F NMR spectroscopy at -80 °C. The CFCl<sub>2</sub><sup>+</sup> and CFCl(OTeF<sub>5</sub>)<sup>+</sup> cations are among the carbocations that have been obtained by reactions of CFCl<sub>3</sub> and CF<sub>2</sub>Cl<sub>2</sub> with XeOTeF<sub>5</sub><sup>+</sup>. The CF<sub>2</sub>Br<sup>+</sup> cation is an intermediate in the reaction of XeOTeF<sub>5</sub><sup>+</sup> with CF<sub>2</sub>Br<sub>2</sub>, undergoing rapid halogen exchange with CF<sub>2</sub>Br<sub>2</sub> to form CFBr<sub>2</sub><sup>+</sup> and CF<sub>3</sub>Br. The CFBr<sub>2</sub><sup>+</sup> cation undergoes further halogen exchange over several hours to form the CBr<sub>3</sub><sup>+</sup> cation and CF<sub>3</sub>Br. Although the highly electrophilic CF<sub>3</sub><sup>+</sup> cation has not been isolated by the reaction of CF<sub>3</sub>Br with XeOTeF<sub>5</sub><sup>+</sup>,<sup> 13</sup>C and <sup>19</sup>F NMR spectroscopy indicates the CF<sub>3</sub><sup>+</sup> cation reacts with BrOTeF<sub>5</sub> to form F<sub>3</sub>CBrOTeF<sub>5</sub><sup>+</sup> and/or abstracts an OTeF<sub>5</sub> group from the Sb(OTeF<sub>5</sub>)<sub>6</sub><sup>- </sup>anion to yield CF<sub>3</sub>OTeF<sub>5</sub> and, ultimately, [SbBr<sub>4</sub>][Sb(OTeF<sub>5</sub>)<sub>6</sub>].</p> <p>The synthesis of C(OTeF<sub>5</sub>)<sub>4</sub> has been accomplished by reaction of CBr4 with Br0TeF5 in SO<sub>2</sub>ClF solution, and has been fully characterized by NMR spectroscopy, Raman spectroscopy, and single-crystal X-ray diffraction, and its geometric parameters have been compared with those of the isoelectronic B(OTeF<sub>5</sub>)<sub>4</sub><sup>-</sup>anion in order to assess the symmetry of the E(OTe)<sub>4</sub><sup>-/0</sup> (E = B, C) subgroup.</p> / Doctor of Philosophy (PhD)
5

Ethylene glycol rapid methods of detection

Blevins, Lori A. January 1900 (has links)
Master of Veterinary Bioscience / Department of Diagnostic Medicine/Pathobiology / Deon Van Der Merwe / Every year thousands of domestic animals are poisoned by ethylene glycol. Exposure is normally orally, but may be dermal, and poisonings are usually accidental and not malicious. Antifreeze, overwhelmingly the source of the ethylene glycol poisoning, is responsible for over 99% of reported cases. Storage, handling and proper disposal of ethylene glycol is extremely important in limiting access to this deadly product. Ethylene glycol exposures were involved in 1737 calls made to the American Society for the Prevention of Cruelty to Animals call center between 2006 and 2011. Dogs were involved in approximately 87% of exposures and cats in 13%. There were no seasonal or breed patterns. The most common clinical signs reported were neurological and gastrointestinal for both cats and dogs. Urinary calcium oxalate crystals were reported in 28.6% of exposed cats, and 21% of dogs. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to detect calcium oxalate crystals in wax-mounted kidneys from twenty total cases, ten of which were suspected ethylene glycol poisoning submitted to the Kansas State Veterinary Diagnostic Laboratory, and ten samples deemed negative by a pathologist using light microscopy. Pure calcium oxalate monohydrate was used as a reference, and a unique absorption peak was detected between wavenumbers 1290 cm[superscript]-1 and 1320 cm[superscript]-1. The drying of kidney tissues resulted in increased sensitivity for calcium oxalate. Crystal detection by the ATR-FTIR was compared to light microscopy. Bi-fringence of crystals allowed microscopic detection, but the ATR-FTIR specificity for the test was 100%, and sensitivity was 80% compared to traditional microscopy for ca-oxalate crystal identification. ATR-FTIR was also used to detect un-metabolized ethylene glycol in vomitus using wavenumbers 1084 cm[superscript]−1, 1039 cm[superscript]−1, and 882 cm[superscript]−1, but ethylene glycol was not detectable. Ethylene glycol concentrations in samples were much too low to be detected as ethylene glycol on the ATR-FTIR, as the limit of detection was not distinguishable until 5000 ppm using a serial dilution. These methods presented simple, reliable, quick, sensitive, stable, and highly adaptable tests for detection, diagnosis and treatment of ethylene glycol poisoning.
6

AvaliaÃÃo da FragilizaÃÃo a 400ÂC e a 475ÂC do AÃo InoxidÃvel FerrÃtico AISI 444 Utilizado em Torres de DestilaÃÃo de PetrÃleo / Evaluation of Embrittlement at 400 Â C and 475 Â C of AISI 444 Ferritic Stainless Steel Used in Oil Distillation Towers

Josà Adailson de Souza 26 July 2004 (has links)
AgÃncia Nacional do PetrÃleo / Os efeitos do envelhecimento a 400&#61616;C e 475&#61616;C na resistÃncia a corrosÃo, nas propriedades mecÃnica e magnÃtica do aÃo inoxidÃvel ferrÃtico AISI 444 foram investigados. O endurecimento causado pelo envelhecimento em ambas temperaturas foi medido, tendo sido observado que à mais intenso a 475ÂC. A susceptibilidade de corrosÃo localizada aumentou com o tempo de envelhecimento nas duas temperaturas, sendo tambÃm mais significativa a 475ÂC do que a 400ÂC. Com o tratamento de dissoluÃÃo a 570ÂC e 675ÂC ocorre a recuperaÃÃo dos valores de dureza e da resistÃncia à corrosÃo do aÃo. Diferente do aÃo inoxidÃvel duplex, o aÃo AISI 444 nÃo apresentou variaÃÃo na forÃa coercitiva e na temperatura de Curie com o aumento do tempo de envelhecimento. Os efeitos nos espectros de MÃssbauer tambÃm foram analisados. / The effects of aging at 400 C and 475 &#61616; &#61616; C in corrosion resistance, mechanical and magnetic properties of the ferritic stainless steel 444 were investigated. The hardening caused by aging in both temperatures was measured, it was observed that is more intense at 475  C. Susceptibility to localized corrosion, increased with aging time at the two temperatures, is also significantly more than 475  C to 400  C. In the treatment of dissolution at 570  C and 675  C is the recovery of hardness and corrosion resistance of steel. Unlike the duplex stainless steel, steel AISI 444 did not change in coercive force and the Curie temperature with increasing aging time. The effects in the MÃssbauer spectra were also analyzed.
7

Técnicas avançadas para caracterização de processos de transporte dependente do Spin /

Nunes Neto, Oswaldo. January 2012 (has links)
Orientador: Carlos Frederico de Oliveira Graeff / Banca: Ivo Alexandre Hummelgen / Banca: Luis Vicente de Andrade Scalvi / O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, POSMAT, tem caráter institucional e integra as atividades de pesquisa em materiais em diversos campi / Resumo: Efeitos de campo magnético em materiais e dispositivos orgânicos não-magnéticos vêm sendo foco de grande destaque na comunidade científica. De maneira a melhor compreender tais fenômenos, este trabalho propôs-se à implementação das técnicas de Espectroscopia de impedância elétrica em correntes alternadad (EIE-AC) na Presença de Campo Magnético e de Ressonância Magnética Detectada Eletricamente (RMDE). Para a montagem dessas técnicas foram utilizados instrumentos convencionais disponiveis no laboratório e as suas arquiteturas foram planejadas para permitir a utilização desses instrumentos em outros sistemas de medida. Programas na plataforma Agilent Vee Pro 9.2 foram desenvolvidos para o controle e aquisição dos dados das medições. A validação do sistema de EIE-AC na Presença de Campo Magnético foi efetuada a partir de medidas em circuitos básicos e num diodo orgânico emissor de luz (OLED) à base da molécula de Alq3, o qual era sabido que este apresentava o efeito de magnetoresistência. A influência do campo magnético sobre o comportamento das impedâncias do OLED de medida só foi percebida significativamente a partir da aplicação de tensões contínuas acima de 4 V, as quais condicionavam o OLED em seu estado emissivo. O fenômeno de Magneto-Impedância foi verificado nessa amostra, sendo que os efeitos mais expressivos ocorreram nas impedâncias imaginárias e para a frequencia em torno de 20Hz. Um segundo efeito de campo magnético de longo prazo de ação sobre o comportamento da impedância da amostra também foi verificado e discutido. Dentre os mecanismos físicos que podem explicar os efeitos observados no OLED, destacam-se os processos de recombinação de carga, o aprisionamento de cargas em defeitos e a ocorrência de polarização magnética das moléculas constituintes do OLED / Abstract: Magnetic Field Effects on non-magnetic organic materials and device have attracted the attention of the scientific community. In order to elucidate those phenomena, this work proposes the implantation of two advanced characterization techniques: Electrical Impedance Spectroscopy in Alternating Current (EIS-AC) in the presence of magnetic field; and electrically detected magnetic resonance (EDMR). Both techniques were implemented using conventional laboratory instruments. Computational routiness were developed with Agilent Vee Pro 9.2 in order to control and acquire data from the measuring instruments. the validation f eIS-AC system was performed by using basic electrical circuits and an Organic Light Emiting Diode (OLED) based in Alq3 molecule, which has the magnetoresistance effect. The magnetic field effects over impedances were only detected when the applied continuous voltage was above 4 V, from which the OLED is in its emiting state. The Magneto-Impedance phenomenon was evidenced in this sample mainly in the imaginary impedances and for frequencies around 20 Hz. A second magnetic field effect, with long time term action over the impedance behavior, was also verified and discussed. Among the possible physical mechanisms behind the magnetic effects, charge recombination process, charge trapping by deffects, and the magnetic polarization of the OLED active molecules are discussed / Mestre
8

Complexos de lantanídeos contendo ligantes organofosforados como matrizes para materiais luminescentes

Francisco, Cristina Santana [UNESP] 25 September 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:35:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-09-25Bitstream added on 2014-06-13T19:45:04Z : No. of bitstreams: 1 francisco_cs_dr_araiq.pdf: 2557839 bytes, checksum: 6e50bdc3b6d442d52debf1600ec04bb1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho foram sintetizados e caracterizados complexos de lantanídeos contendo ligantes organofosforados. Os ligantes utilizados neste trabalho foram: ácido difenilfosfínico (HDPP), ácido benzil(fenil)fosfínico (HBPP) e ácido (1,4-fenilenodimetileno)-bis-(fenilfosfínico) (H2PMPP). Os compostos foram obtidos através de reação de precipitação e síntese hidrotérmica em diferentes condições. Para os compostos obtidos através de reação de precipitação, observa- se uma tendência a formação de partículas esféricas e aglomerados. Os complexos sintetizados via síntese hidrotérmica apresentam partículas em forma de bastões e formação de aglomerados. Os espectros de luminescência indicam a presença de dois ou mais sítios de simetria para os difenilfosfinatos de ítrio dopados com európio (Y(DPP)3:Eu(%)). Para os benzil(fenil)fosfinatos (Y(BPP)3:Eu(%)) e (1,4- fenilenodimetileno)-bis-(fenilfosfinatos) (Y(PMPP)3:Eu(%)) de ítrio dopados com európio foi observada a presença da transição 5 D0→7 F0, indicando que o íon Eu3+ nestes compostos ocupa um sítio de simetria sem centro de inversão. As curvas de decaimento de estado excitado sugerem a presença de dois ou mais sítios de simetria nos complexos Y(DPP)3:Eu(%). Para os compostos Y(BPP)3:Eu(%) e Y2(PMPP)3:Eu(%) foi observada a contribuição de apenas um sítio de simetria. Os parâmetros de intensidades Ω2 e Ω4 dos complexos Y(DPP)3:Eu(%) indicam que o íon Eu3+ ocupa sitos de simetria semelhantes nos difenilfosfinatos, e nos compostos Y(BPP)3:Eu(%) e Y2(PMPP)3:Eu(%) indicam a presença de sítios de baixa simetria. A emissão do Eu3+ e Tb3+ nos Y(DPP)3:CeEuTb(%) aumenta em função da concentração do íon Ce3+ , indicando a ação do cério como íon sensibilizador nestes compostos através dos processos de transferência de energia, do íon Ce(III) para os íons ativadores Eu(III) e Tb(III)... / In this work lanthanides complexes containing organophosphorus ligands were synthesized and characterized. The following ligands were used diphenilphosphinic acid H(DPP), benzyl(phenyl)phosphinic acid (BPP) and (1,4- phenylenedimethylene)-bis-(phenylphosphinic) (PMPP). The compounds obtained through hydrothermal route presented a greater structural organization of the system regarding the obtained complexes by precipitation. For obtained compounds through precipitation, spherical- particle and cluster formation are observed. The synthesized compounds through hydrothermal rout presented particles in sticks form and cluster formation. The luminescence spectral indicatee the presence of two or more symmetry sites to europium-doped diphenylphosphinate of yttrium complexes (Y(DPP)3:Eu%). For europium-doped benzyl(phenyl)phosphinate (Y(BPP)3:Eu%) and europium doped (1-4-phenylenedimethylene)-bis- (phenylphosphinate) (Y2(PMPP)3:Eu%) complexes the presence only a non- centrossymetry site was observed. The presence of 5 D0→7 F0 an indicative of the low symmetry in about Eu(III) ion. The values of emission lifetime confirmed the presence of two or more symmetry sites to (Y(DPP)3:Eu%). The lifetime for (Y(BPP)3:Eu%) and (Y2(PMPP)3:Eu%) complexes confirmed the presence a non-centrossymmetry sites contribuition only. were observed the presence only a non-centrossymetry site, the presence of 0-0 transition is indicative that the symmetry in about Eu(III) low. The values of emission lifetime confirmed the presence a non-centrossymmetry site contribution only. xi The intensity parameters Ω2 e Ω4 indicate that Y(BPP)3:Eu(%) e Y(PMPP)3:Eu(%) present non-centrossimetric sites. The emission of Eu3+ and Tb3+ in the Y(DPP)3:CeEuTb(%)is favored with the increasing of the concentration cerium indicatin that energy transfer process process of Ce(III) to Eu (III) and Tb (III) is favored... (Complete abstract click electronic access below)
9

Complexos de lantanídeos contendo ligantes organofosforados como matrizes para materiais luminescentes /

Francisco, Cristina Santana. January 2009 (has links)
Orientador: Elizabeth Berwerth Stucchi / Banca: Sidney José Lima Ribeiro / Banca: Pedro Paulo Corbi / Banca: Sergio Antonio Marques de Lima / Banca: Robert Alan Burrow / Resumo: Neste trabalho foram sintetizados e caracterizados complexos de lantanídeos contendo ligantes organofosforados. Os ligantes utilizados neste trabalho foram: ácido difenilfosfínico (HDPP), ácido benzil(fenil)fosfínico (HBPP) e ácido (1,4-fenilenodimetileno)-bis-(fenilfosfínico) (H2PMPP). Os compostos foram obtidos através de reação de precipitação e síntese hidrotérmica em diferentes condições. Para os compostos obtidos através de reação de precipitação, observa- se uma tendência a formação de partículas esféricas e aglomerados. Os complexos sintetizados via síntese hidrotérmica apresentam partículas em forma de bastões e formação de aglomerados. Os espectros de luminescência indicam a presença de dois ou mais sítios de simetria para os difenilfosfinatos de ítrio dopados com európio (Y(DPP)3:Eu(%)). Para os benzil(fenil)fosfinatos (Y(BPP)3:Eu(%)) e (1,4- fenilenodimetileno)-bis-(fenilfosfinatos) (Y(PMPP)3:Eu(%)) de ítrio dopados com európio foi observada a presença da transição 5 D0→7 F0, indicando que o íon Eu3+ nestes compostos ocupa um sítio de simetria sem centro de inversão. As curvas de decaimento de estado excitado sugerem a presença de dois ou mais sítios de simetria nos complexos Y(DPP)3:Eu(%). Para os compostos Y(BPP)3:Eu(%) e Y2(PMPP)3:Eu(%) foi observada a contribuição de apenas um sítio de simetria. Os parâmetros de intensidades Ω2 e Ω4 dos complexos Y(DPP)3:Eu(%) indicam que o íon Eu3+ ocupa sitos de simetria semelhantes nos difenilfosfinatos, e nos compostos Y(BPP)3:Eu(%) e Y2(PMPP)3:Eu(%) indicam a presença de sítios de baixa simetria. A emissão do Eu3+ e Tb3+ nos Y(DPP)3:CeEuTb(%) aumenta em função da concentração do íon Ce3+ , indicando a ação do cério como íon sensibilizador nestes compostos através dos processos de transferência de energia, do íon Ce(III) para os íons ativadores Eu(III) e Tb(III)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work lanthanides complexes containing organophosphorus ligands were synthesized and characterized. The following ligands were used diphenilphosphinic acid H(DPP), benzyl(phenyl)phosphinic acid (BPP) and (1,4- phenylenedimethylene)-bis-(phenylphosphinic) (PMPP). The compounds obtained through hydrothermal route presented a greater structural organization of the system regarding the obtained complexes by precipitation. For obtained compounds through precipitation, spherical- particle and cluster formation are observed. The synthesized compounds through hydrothermal rout presented particles in sticks form and cluster formation. The luminescence spectral indicatee the presence of two or more symmetry sites to europium-doped diphenylphosphinate of yttrium complexes (Y(DPP)3:Eu%). For europium-doped benzyl(phenyl)phosphinate (Y(BPP)3:Eu%) and europium doped (1-4-phenylenedimethylene)-bis- (phenylphosphinate) (Y2(PMPP)3:Eu%) complexes the presence only a non- centrossymetry site was observed. The presence of 5 D0→7 F0 an indicative of the low symmetry in about Eu(III) ion. The values of emission lifetime confirmed the presence of two or more symmetry sites to (Y(DPP)3:Eu%). The lifetime for (Y(BPP)3:Eu%) and (Y2(PMPP)3:Eu%) complexes confirmed the presence a non-centrossymmetry sites contribuition only. were observed the presence only a non-centrossymetry site, the presence of 0-0 transition is indicative that the symmetry in about Eu(III) low. The values of emission lifetime confirmed the presence a non-centrossymmetry site contribution only. xi The intensity parameters Ω2 e Ω4 indicate that Y(BPP)3:Eu(%) e Y(PMPP)3:Eu(%) present non-centrossimetric sites. The emission of Eu3+ and Tb3+ in the Y(DPP)3:CeEuTb(%)is favored with the increasing of the concentration cerium indicatin that energy transfer process process of Ce(III) to Eu (III) and Tb (III) is favored... (Complete abstract click electronic access below) / Doutor
10

Hydratace hyaluronové kyseliny / The hydration of hyaluronic acid

Průšová, Alena January 2008 (has links)
Hydratace patří mezi nejdůležitější faktory ovlivňující sekundární strukturu a tím i funkci molekul v živých systémech. Díky vysoké afinitě tvoří molekuly vody specifické struktury jejichž složení a fyzikální vlastnosti jsou ovlivněny přítomností studované látky. Hyaluronan patří mezi biomolekuly s obrovskou schopností vázat a zadržovat vodu. Cílem této práce bylo prozkoumat hydratační vlastnosti hyaluronanu o různé molekulové hmotnosti a vyčíslit množství molekul vody v jednotlivých hydratačních vrstvách. V první části práce byla využita metoda diferenční kompenzační kalorimetrie. V druhé části diplomové práce, na základě rozdílné kompresibility, byla vázaná voda studována metodou vysoko rozlišovací ultrazvukové spektroskopie.

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