Doctor of Philosophy / Department of Chemistry / Emily McLaurin / Quantum dots are nanocrystalline semiconductors in which the size is so small that optoelectronic properties are size dependent. QDs have a lot of applications in displays, solar cells, lasers, light emitting diodes, etc. The optoelectronic properties of QDs depend on their size, composition, the shape of the particles and also the surface chemistry of the QDs. Phosphine based precursors have been mostly used in the synthesis of QDs. Due to the lack of tunable reactivity, this class of precursors, QDs with different shape are obtained by under different reaction conditions. With that, branched QDs are less likely to be obtained in one step reaction using phosphine based precursors. To synthesis QDs with a branched structure, in a single step synthesis, mixtures of precursors with different reactivity were used. Using dichalcogenides mixture, CdSe₁-xSx hyperbranched supra-quantum dots (HSQDs) where synthesized in a one-step microwave-assisted synthesis and shape evolution mechanism of formation of NCs studied. It is shown that the NCs formed in three steps of nucleation, aggregation, and growth. By controlling the reaction conditions, simple branched tetrapod NCs are prepared, but the obtained NCs have no emission due to unpassivated surface and defects which work as trap. To obtain luminescent NCs obtained through doping. Hyperbranched Mn²+:ZnSe₁-xSx NCs also prepared using a mixture of Ph₂Se₂ and Me₂S₂. The shape evolution mechanism of the formation of NCs was studied and it is shown that the NCs are formed via oriented attachment of initially formed nanoparticles. The NCs used for thiol sensing, and it observed that they have a better sensitivity and detection limit than spherical QDs. Although hyperbranched NCs have higher sensitivities over nonbranched NCs but, the spherical NCs have better detection limit and can dispersed in aqueous medium by ZnS shell growth followed by silica shell formation. To study the effect of ZnS shell thickness on sensing property of NCs, a set of spherical Mn:ZnSe@ZnS with different ZnS shell thickness were prepared and used for thiol sensing. It observed that in organic medium, thinner ZnS layer gives the highest sensitivity and QDs with thick ZnS shell layer have less sensitivity. For measurement in aqueous medium, QDs transferred to PBS buffer after formation of silica shell over QDs. It observed that NCs with a thin ZnS shell layer lose their emission and sensing completely. Thick ZnS shell protects NCs in the silica shell formation step but they show very low sensitivity to thiol compounds as well. ZnS shell with medium thickness gives the best sensitivity in an aqueous medium. The emission of Mn:ZnSe@ZnS QDs originated from d-d electron transition of Mn(II) ions and is independent to the size of QDs. To extend our study to QDs with band edge emission, preparation of luminescent InP QDs by post-synthetic modification is studied. InP NCs were synthesized using heat up method and successive injection of precursors. Narrow size distribution NCs obtained after size selection precipitation. Emissive NCs obtained after etching using InCl3 and fluoride containing salts. The study showed that more InCl3 case more etching and presence of fluoride-containing salt is necessary for band edge emission of the NCs.

Xu, Yeming = I-III-VI₂χχχII-VI和I-III-VI₂χχχχχχχχχχχχχχχ : 合成, 表征以及潛在应用 / 徐業明. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 130-134). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Xu, Yeming = I-III-VI₂ zu yi ji II-VI he I-III-VI₂ zu fu he na mi cai liao he tuo men de yi zhi jie gou : he cheng, biao zheng yi ji qian zai ying yong / Xu Yeming.

A baixa seletividade dos métodos convencionais para diagnóstico e terapia de neoplasias, bem como o fato de nem sempre alcançarem o sucesso terapêutico desejado, configuram dificuldades para a prática oncológica. Diante disso, os anticorpos monoclonais (AcMs) radiomarcados, aplicados em técnicas diagnósticas, têm se destacado, visto que permitem a entrega seletiva da radiação ao alvo de interesse. A metodologia Radioimunodiagnóstico (RID), utilizando AcM anti-EGFR radiomarcado, possibilita triagem prévia, avaliando a resistência ao tratamento e estratificando pacientes que possam apresentar benefícios à imunoterapia com cetuximabe. Além disso, permite monitorar a progressão da terapia, visando tratamento mais efetivo e direcionado, promulgando a abordagem da medicina personalizada. No Brasil, ainda não há radioimunoconjugado disponível para diagnóstico e seguimento do câncer. Nesse contexto, o objetivo com este trabalho foi o de desenvolver uma formulação farmacêutica para padronizar uma rotina de produção dos radiofármacos para radioimunodiagnóstico de câncer de cabeça e pescoço e de câncer colorretal: cetuximabe-DTPA-111In e cetuximabe-DFO-89Zr. Em adição, corroborar na elucidação dos mecanismos de resistência das células tumorais à terapia com o cetuximabe, através da realização de estudos de ligação do radioimunoconjugado à receptores celulares. Em relação aos radiofármacos estudados, destaca-se que os processos de conjugação do cetuximabe com os quelantes DTPA, na razão molar 1:20, e com o DFO, 1:5, foram bem-sucedidos e otimizados, demonstrando boa reprodutibilidade. Os imunoconjugados apresentaram preservação da imunorreatividade e alta estabilidade quando armazenados a -20°C por até seis meses. Esses imunoconjugados, quando radiomarcado com 111In e 89Zr, exibiram pureza radioquímica superior a 95%, sem necessidade de purificação pós-marcação, e estabilidade por tempo que possibilita seu transporte às clínicas distantes do centro produtor. As análises in vitro do cetuximabe-DTPA-111In em células FaDu-C10 (linhagem resistente) demonstraram percentual inexpressivo de ligação e internalização do radioimunoconjugado, congruindo na explanação do modelo de resistência conferido à linhagem. O estudo de corpo inteiro em MicroPET/TC revelou redução no perfil de captação no grupo de bloqueio, com excesso de cetuximabe não marcado, e intensa captação do cetuximabe-DFO-89Zr pelo tumor de células escamosas no grupo sem bloqueador, confirmando a especificidade in vivo do radioimunoconjugado. Os estudos de biodistribuição dos radiofármacos foram compatíveis com os descritos em literatura e validaram os resultados obtidos por imagens em MicroSPECT/TC e MicroPET/TC, além de apresentarem apreciável captação tumoral, considerando os tempos analisados. A estabilidade alta in vivo e a eficácia da marcação foram confirmadas pela baixa captação óssea e em tecidos não alvos. O melhor intervalo pós-injeção do radiofármaco para avaliação in vivo foi após cinco dias da administração. Conclui-se, portanto, que os radioimunoconjugados para imuno-SPECT e imuno-PET, cetuximabe-DTPA-111In e cetuximabe-DFO-89Zr, são ferramentas promissoras para diagnóstico e monitoramento de câncer receptor específico (EGFR) e para estratificação de pacientes à terapia anti-EGFR, encorajando a continuidade deste projeto para futuros estudos clínicos. / The low selectivity of conventional methods for cancer diagnosis and therapy, as well as the fact that these methods could not achieve the desired therapeutic success, constitute difficulties for the oncological practice. In this regard, radiolabeled monoclonal antibodies (mAbs) applied in diagnostic techniques have been highlighted, since they allow the selective delivery of the radiation to the specific target. The radioimmunodiagnosis methodology (RID), using radiolabeled anti-EGFR mAbs, enables previous screening, evaluating resistance to treatment and stratifying patients who may present benefits to cetuximab immunotherapy. In addition, it allows monitoring the progression of the therapy, aiming for a more effective and directed treatment, leading the personalized medicine approach. A radioimmunoconjugate is not yet available for diagnosis and management of cancer in Brazil. In this context, this research was carried out to develop a pharmaceutical formulation to standardize a routine production of radiopharmaceuticals for diagnosis and monitoring head and neck cancer and colorectal carcinoma: 111In-DTPA-cetuximab and 89Zr-DFO-cetuximab. In addition, corroborate in the elucidation of the tumor cells resistance mechanisms to EGFR-targeted therapy, through in vitro and in vivo radioimmunoconjugate binding studies to cellular receptors. Regarding to the radiopharmaceuticals studied, cetuximab was conjugated to DTPA chelator at 1:20 molar ratio and to DFO at 1: 5, and these processes were successful and optimized, showing good reproducibility. Immunoconjugates showed preservation of immunoreactivity and high stability when stored at -20 °C for up to 6 months. These immunoconjugates when radiolabeled with 111In and 89Zr have exhibited radiochemical purity above 95%, without any post-labeling purification, and the radioimmunoconjugates have demonstrated stability for a time that allows them to be transported to clinics far from the producer center. 111In-DTPA-cetuximab in vitro analyzes in FaDu-C10 cells (resistant cell line) has presented an inexpressive percentage of binding and internalization of the radioimmunoconjugate, ensuring the resistance model conferred to this cell line. The MicroPET/CT imaging study has revealed a reduction in uptake profile for \"Blocking\" group, with an excess of unlabeling cetuximab, and an intense 89Zr-DFO-cetuximab uptake in squamous cell tumor for \"Non-blocking\" group, that evidenced the in vivo radioimmunoconjugate specificity. The biodistribution studies of the radiopharmaceuticals were well-matched with those described in the literature and they validated the results obtained through the MicroSPECT/CT and MicroPET/ CT images. In addition, these studies in vivo have displayed a substantial tumor uptake, according with the analyzed time points. The radioimmunoconjugate showed high in vivo stability and labeling procedures efficiency, which were confirmed by low bone and non-target tissues uptake. The best post-injection interval for in vivo evaluation is after 5 days of radioimmunoconjugate administration. In conclusion, the radioimmunoconjugates for immuno-SPECT and immuno-PET, 111In-DTPA-cetuximab and 89Zr-DFO-cetuximab, are promising tools for diagnosis and monitoring of specific receptor cancer (EGFR), as well as for stratification of patients to anti-EGFR therapy, and thus encourages the continuity of this project for future clinical trials.

Neste trabalho, analisamos as propriedades estruturais, morfológicas e óticas de filmes finos de nitreto de índio, depositados em diferentes tipos de substratos (Si , safira-C, safira-A, safira-R, GaN/ safira e vidro) pelo método de deposição as s i s t ida por feixe de elétrons com energia de íons entre 100 e 1180 eV. A temperatura de substrato durante o processo de deposição variou da temperatura ambiente (TA) à 450oC, e ARR( I/A) ,que é a razão do f luxo de íons incidentes no feixe de íons relativa ao f luxo de átomos de In evaporados , de 0,8 até 4,5. O crescimento de InN cristalino foi fortemente influenciado pela orientação cristalográfica do substrato e os filmes sobre safira-C, safira-A e GaN/ safira foram os que apresentaram maior cristalinidade. O melhor valor de energia de íons foi de 100 eV para a formação de InN cristalino e sua cristalinidade aumentou com o aumento da temperatura do substrato. Não observamos influências de ARR( I/A) sobre a cristalinidade de InN e os filmes preparados em TA sobre GaN/ safira apresentaram InN amorfo. / In thi s work, we analyzed the structural , morphological and optical properties of thin indium nitride films grown on some types of subs t rate (Si , c-plane sapphire, a-plane sapphire, r -plane sapphire, GaN/ sapphire and glass ) by the ion beam as s is ted deposition method with ion energy of 100-1180 eV. The substrate temperature during deposition ranged from room temperature (RT) to 450oC and ARR ( I/A) , from 0.8 to 4.5. The growth of crystalline InN was strongly influenced by the crystallographic orientation of substrate and the films on c-plane sapphire, a-plane sapphire and GaN/ sapphire provided more favorable result s . The best value of ion energy was found to be 100 eV for the format ion of crystalline InN and this crystallization increased with increasing the substrate temperature. We found that influence of ARR( I/A) on the crystallization of InN was imperceptible and that the f ilm prepared at RT on the GaN/ sapphire was amorphous of InN.

No description available.

The use of positron emission tomography (PET) has so far mainly been limited to a few nuclides with short half-lives such as 11C and 18F. Certain applications require nuclides with longer half-lives, such as 76Br and 52Fe. In radionuclide therapy positron emitting analogues of therapeutic nuclides, such as 110mIn, or daughter nuclides, such as 134La, can enable improved dosimetry with the use of PET. A challenge associated with the use of these positron emitters is that they emit gamma radiation in cascade with positrons, which complicates quantitative PET imaging. Other possible problems are the high energies of the emitted positrons, and the decay of 52Fe to the short-lived positron emitter 52mMn. Performance measurements were made to investigate the effects of these decay characteristics on the quantitative accuracy, spatial resolution, and other parameters of PET. The distribution of gamma radiation coincidences in PET data was studied and correction methods were implemented and evaluated. PET resolution degrades with 1-2 mm for the studied nuclides in comparison with 18F. The implemented sinogram tail fit and delayed coincidence based gamma radiation coincidence correction methods lead to a quantitative accuracy similar as for 18F and to improved image contrast. Standard dead time corrections are not adequate for gamma-emitting nuclides. Noise equivalent count rates are considerably lower for 76Br than for 18F at clinically relevant radioactivity concentrations. A method to correct 52Fe patient data for the contribution of 52mMn is discussed. The use of 110mIn is evaluated in a patient study and compared to SPECT imaging with 111In. A dosimetric and PET evaluation of the use of 134Ce/134La for radionuclide therapy and dosimetry is presented. Dosimetry of 76Br-labelled antibodies is studied in a pig model. Finally, the possibility to use PET for dosimetry during radionuclide therapy is studied and a nonuniform dose calculation program is presented.

This work was initially launched to study the synthesis of low-valent group 13 compounds bearing the bis(imino)pyridine ligand framework. Since its inception, this project has grown beyond the boundaries of group 13 to include low valent tin, silver, and rhenium. Alongside the reports of novel coordination compounds, we utilized computational chemistry to uncover unprecedented interactions which challenge conventional concepts of bonding. Synthesis, characterization, and complimentary computational studies are presented herein. Chapter 1 presents a historical overview of the bis(imino)pyridine ligand as well as our synthetic methodology and characterization of new ligand variants we have contributed to the literature. Chapter 2 presents the synthesis of a series of In(I) and In(III) bis(imino)pyridine complexes with varied sterics. Ligand-metal interaction and effect of ligand steric bulk on complex stability, as well as computational studies highlighting weak covalent interactions will be discussed. Chapter 3 presents the synthesis of Ga(III) bis(imino)pyridine complexes. Reactivity with “GaI” synthon as well as varied-stoichiometry one-pot synthesis attempts to generate low valent Ga-bis(imino)pyridine complexes will be discussed. Chapter 4 presents the synthesis of a series of Tl(I) bis(imino)pyridine complexes with varied sterics analogous to the approach taken with indium(I). Unprecedented weak ligand-metal as well as Tl-arene interactions will be discussed. Chapter 5 presents the synthesis of a series of Sn(II) bis(imino)pyridine complexes with varied sterics and halide substituents. Preferential cation-anion pair formation and attempted reactivity will be discussed. Chapter 6 presents the synthesis of a series of Ag(I) bis(imino)pyridine complexes with varied sterics. Resulting ligand-metal interactions as well as reactivity towards Lewis basic donor ligands will be discussed. Chapter 7 presents the synthesis of first crystallographically authenticated examples of rhenium(I) pincer complexes utilizing the bis(imino)pyridine ligand. Chapter 8 presents a general conclusion to the work.

Unique physical properties such as small effective mass, high electron drift velocities, high electron mobility and small band gap energy make InN a candidate for applications in high-speed microelectronic and optoelectronic devices. The aim of this research is to understand the surface properties, desorption kinetics and thermal stability of InN epilayers that affect the growth processes and determine film quality as well as device performance and life time. We have investigated the structural properties, the surface desorption kinetics, and the thermal stability using Auger electron spectroscopy (AES), x-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), high resolution electron energy loss spectroscopy (HREELS), and temperature programmed desorption (TPD). Investigations on high pressure chemical vapor deposition (HPCVD)-grown InN samples revealed the presence of tilted crystallites, which were attributed to high group V/III flux ratio and lattice mismatch. A study of the thermal stability of HPCVD-grown InN epilayers revealed that the activation energy for nitrogen desorption was 1.6±0.2 eV, independent of the group V/III flux ratio. Initial investigations on the ternary alloy In0.96Ga0.04N showed single-phase, N-polar epilayers using XRD and HREELS, while a thermal desorption study revealed an activation energy for nitrogen desorption of 1.14 ± 0.06 eV. HREELS investigations of atomic layer epitaxy (ALE)-grown InN revealed vibrational modes assigned to N-N vibrations. The atomic hydrogen cleaned InN surface also exhibited modes assigned to surface N-H without showing In-H species, which indicated N-polar InN. Complete desorption of hydrogen from the InN surface was best described by the first-order desorption kinetics with an activation energy of 0.88 ± 0.06 eV and pre-exponential factor of (1.5 ± 0.5) ×105 s-1. Overall, we have used a number of techniques to characterize the structure, surface bonding configuration, thermal stability and hydrogen desorption kinetics of InN and In0.96Ga0.04N epilayers grown by HPCVD and ALE. High group V/III precursors ratio and lattice mismatch have a crucial influence on the film orientation. The effects of hydrogen on the decomposition add to the wide variation in the activation energy of nitrogen desorption. Presence of surface defects lowers the activation energy for hydrogen desorption from the surface.

No description available.

No description available.