Thesis: M.S., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 1979 / Includes bibliographical references. / by Leslie Louis Szepesi, Jr. / M.S. / M.S. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

The Enåsen gold deposit is located in Gävleborg county in central Sweden. Mining operations at Enåsen took place from 1984 to 1991 with Au as the main target for exploitation. The deposit has been interpreted as a metamorphosed Palaeoproterozoic analogue to near-recent epithermal Au mineralisations of a high sulphidation type. Its present mineralogy, textural-structural features, and morphology have been suggested to be the result of a combination of later deformation and regional Svecokarelian metamorphism at upper amphibolite to granulite facies conditions of the original epithermal deposit and it’s hydrothermally altered host rock. The main ore body now consists of a mineralised sillimanite quartzite gneiss. The aim of the project was to characterise the ore mineralogy, petrography and its paragenesis, evaluate the potential of Enåsen in terms of critical metals, and to test a hypothesis of partial ore melting.Among the most frequent ore minerals in the deposit are pyrite, chalcopyrite, pyrrhotite, bornite and tetrahedrite-tennantite, with variable but less abundant sulphides including covellite, digenite, mawsonite, stannite, arsenopyrite, cobaltite, galena, marcasite, sphalerite and pentlandite. Additionally, native gold, Se-bearing tellurobismuthite, hessite, tsumoite, pilsenite, rickardite, vulcanite, altaite, molybdenite, frohbergite, montbrayite, tellurantimony, löllingite and tellurbismuthantimony. While not an ore mineral here, rutile occurs abundantly. The ore mineral assemblages have seemingly at least partially melted. This is evidenced by failed quenching textures in the form of abundant multi-scale symplectites, potential sharp dihedral angles, localised concentrations of low melting point chalcophile elements (LMCE) + Au and Ag and arrays of multiphase sulphide/sulphosalt ± gold inclusions, as well as available mineral stability data considering that the ore assemblages have been subjected to upper amphibolite/granulite facies conditions followed by ductile and brittle deformation stages. Some ore mineral relationships have been described. Further studies would be required for a full paragenesis. The potential of Enåsen type deposits in terms of critical or near critical metals and semi-metals is likely to be as biproduct extraction in a mining operation aimed at gold. The most relevant element is likely to be bismuth, followed by tellurium and antimony.

Nesta tese apresentamos um estudo sistemático da reação de alquinilação de teluretos Z-vinílicos promovida por PdCl2 e CuI. O sucesso de tal reação foi dependente da quantidade de PdCl2 empregado, por outro lado, o sal de cobre (I) não apresentou influência significativa sobre o curso da reação. Posteriormente, empregando PdCl2 em quantidades catalíticas, vários agentes oxidantes ou aditivos foram testados. No entanto, o resultado mais significativo foi obtido quando CuCl2 foi usado na presença de ar. Este resultado deu origem a uma nova metodologia para a alquinilação de teluretos Z-vinílicos, que emprega PdCl2 em quantidade catalítica e CuCl2 em excesso. Adicionalmente, um mecanismo para a reação desenvolvida foi proposto com base em experimentos realizados empregando espectroscopia de massas. Tendo em vista o alto custo dos reagentes de paládio, foram implementadas metodologias para promover a formação de ligações carbono-carbono, usando teluretos vinílicos e reagentes organometálicos na presença de quantidades catalíticas de complexos de níquel (II). Na última etapa do nosso trabalho, teluretos Z-vinílicos quirais foram sintetizados usando biocatálise como ferramenta, sendo posteriormente submetidos à reação de acoplamento resultando em álcoois enínicos de configuração Z quirais. A seqüência de reações foi testada inicialmente em sua versão racêmica. / In this thesis we report a systematic study concerning the alkynylation of Z-vinylic telurides promoted by PdCl2 and CuI. The performance of such reaction was dependent of the amount of PdCl2 employed. On the other hand, the copper (I) salt did not show significant influence in the course of the reaction. Afterwards, employing PdCl2 in catalytic amounts, several oxidizing agents or additives were tested. The most significant result was obtained when CuCl2 was used in the presence of air. This finding brought to light a new methodology for alkynylation of Z-vinylic telurides that employs catalytic amount of PdCl2 and CuCl2 excess. In addition, a mechanism for the new reaction has been proposed with basis in the data obtained by mass spectrometric experiments. In view of the high cost of the palladium reagents, we developed methodologies that promote the formation of carbon-carbon bonds by using vinylic tellurides and organometallic reagents in the presence of catalytic amounts of nickel (II) complexes. In the last stage of our work, chiral Z-vinylic tellurides were synthesized by using biocatalysis as a tool. After that, the chiral tellurides were submitted to the coupling reaction affording chiral enynic alcohos with Z configuration. The reaction sequence was tested initially in its racemic version.

Nesta tese foram desenvolvidas metodologias sintéticas para a abertura de N-tosilaziridinas, provenientes de aminoácidos, via arilcianocupratos de ordem superior, os quais foram gerados pela reação de troca telúrio/cobre entre teluretos arílicos e cianocupratos; tais aberturas levam à formação de estruturas análogas a fenetilaminas em bons rendimentos, as quais possuem atividades farmacológicas interessantes. Adicionalmente, um conjunto de amino teluretos contendo diferentes grupos protetores foram preparados a partir dos respectivos aminoálcoois, em bons rendimentos (72 a 83%), e avaliados como potenciais espécies nucleofílicas. Os teluretos, que contêm como grupo protetor benzoíla, foram utilizados em reações de troca telúrio/lítio, gerando as espécies dilitiadas, as quais foram capturadas com diversos eletrófilos, levando à formação de aminoálcoois de cadeia maior e também à formação de análogos de fenetilaminas em bons rendimentos. Nesta tese também foram estudadas reações que envolvem química de arinos, os quais podem ser gerados de várias maneiras. Dentre essas formas para produzir os arinos, destacamos o uso de 2-(trimetilsilil)fenil triflato, o qual, na presença de fontes de íons fluoreto em solvente polar aprótico, gera a espécie reativa. Empregamos essa metodologia para geração de benzinos na reação de inserção em ligações do tipo σ de disselenetos de diarila. Tendo visto o sucesso da metodologia desenvolvida, decidimos sintetizar outros arinos derivados do 2-(trimetilsilil)fenil triflato e empregá-los em outro tipo de reação de inserção em ligações do tipo σ, desta vez em ligações entre selênio/estanho de tributil(fenilselanil)estanana, levando a uma difuncionalização nas posições 1 e 2 do anel aromático. / In this PhD thesis we developed a synthetical methodology for the ring opening reaction of N-tosyl aziridines by high order arylcyanocuprates that have been generated by tellurium/copper exchange reaction between aryl tellurides and cyanocuprates. These ring opening reactions lead to an interesting class of phenethylamines in good yields. Additionally, a set of tellurium amines containing different protecting groups were conveniently prepared in good yields (72 - 83%) from aminoalcohols and evaluated as potencial nucleophilic species. The corresponding tellurium amines have been evaluated in the tellurium/lithium exchange reaction. The nitrogen-containing organolithium compounds were efficiently prepared by using N-Bz tellurium amines and a mixture of n-butyllithium and lithium naphthalenide (LiNp) to performe the exchange reaction. The dianion intermediates were trapped with a wide range of electrophiles, resulting in this corresponding products in good to excellent yields. The reaction was also employed in the synthesis of phenethylamines. In this work we also studied reactions involving aryne chemistry, that are reactive species. A number of methods for benzyne formation have been reported in the literature. Among them we pay particular attention to the use of 2-(trimethylsilyl)aryl triflates in the presence of fluoride ion sources and aprotic polar solvents that generate this reactive species. We employed this methodology for generation of benzyne in the insertion reaction of diaryl diselenide σ bond. In view of the success of the developed methodology, we decided to synthesize other ayne derivatives from 2-(trimethylsilyl)phenyl triflate and use them on another type of σ bond insertion reaction. The insertion reaction of arynes into Se-Sn sigma bond of tributyl(phenylselanyl)stannane, leading a double functionality in the aromatic system.

[Truncated abstract] Infrared photodiodes fabricated in HgCdTe achieve near-ideal performance, however, in comparison with other semiconductors, processing techniques for HgCdTe are expensive and have relatively low yields. Reactive-ion-etching (RIE) in a H2⁄CH4 gas mixture, a process primarily used for material removal, will cause p-to-n type conversion in HgCdTe. It has been shown, by several groups, that infrared photodiodes fabricated with a process technology based on RIE p-to-n type-conversion achieve high yields with state-of-the-art performance. For this technology to be accepted RIE formed n-on-p photodiodes must demonstrate junction stability under normal operating conditions. Along with a stable junction, a compatible passivation technology that is able to withstand processing and operation temperatures is required. This thesis investigates the RIE p-to-n type-conversion mechanism in HgCdTe with the aim of demonstrating bake stable RIE formed junctions, and gaining an insight to the processes by which RIE type-conversion occurs. In pursuing these aims, two complimentary objectives were required, namely, the development of a passivation technology compatible with RIE formed junctions, and the development of a detailed I-V/Rd-V model for HgCdTe photodiodes. As a result of these objectives, this thesis presents a double-layer ZnS on CdTe passivation technology with which stable RIE-formed n-on-p junctions in HgCdTe are demonstrated. Using this process technology, mid-wave infrared (MWIR) HgCdTe photodiodes have been fabricated and subjected to a bake in vacuum at 80°C for 175 hours, after which there is negligible degradation in the zero-bias Dynamic-Resistance Area product (RoA) from the pre-bake values

[Truncated abstract] Infrared (IR) detectors have many applications, from homeland security and defense, to medical imaging, to environmental monitoring, to astronomy, etc. Increasingly, the wave- length dependence of the IR radiation is becoming important in many applications, not just the total intensity of infrared radiation. There are many types of infrared detectors that can be broadly categorized as either photon detectors (narrow band-gap materials or quantum structures that provide the necessary energy transitions to generate free car- riers) or thermal detectors. Photon detectors generally provide the highest sensitivity, however the small transition energy of the detector also means cooling is required to limit the noise due to intrinsic thermal generation. This thesis is concerned with the tech- nique of resonant-cavity-enhancement of detectors, which is the process of placing the detector within an optically resonant cavity. Resonant-cavity-enhanced detectors have many favourable properties including a reduced detector volume, which allows improved operating temperature, or an improved signal to noise ratio (or some balance between the two), along with a narrow spectral bandwidth. ... Responsivity of another sample annealed for 20 hours at 250C in a Hg atmosphere (ex-situ) also shows resonant performance, but indicates significant shunting due the mirror layers. There is good agreement with model data, and the peak responsivity due to the absorber layer is 9.5×103 V/W for a 100 'm ×100 'm photoconductor at 80K. An effective lifetime of 50.4 ns is extracted for this responsivity measurement. The responsivity was measured as a function of varying field, and sweepout was observed for bias fields greater than 50 V/cm. The effective lifetime extracted from this measurement was 224 ns, but is an over estimate. Photodiodes were also fabricated by annealing p-type Hg(1x)Cd(x)Te for 10 hours at 250C in vacuum and type converting in a CH4/H2 reactive ion etch plasma process to form the n-p junction. There is some degradation to the mirror structure due to the anneal in vacuum, but a clear region of high reflection is observed. Measurements of current-voltage characteristics at various temperatures show diode-like characteristics with a peak R0 of 10 G measured at 80K (corresponding to an R0A of approximately 104 cm2. There was significant signal from the mirror layers, however only negligible signal from the absorber layer, and no conclusive resonant peaks.

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Orientador: Prof. Dr. Rodrigo Luiz Oliveira Rodrigues Cunha / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciência e Tecnologia/Química, 2015. / Organocalcogenetos sao importantes reagentes e intermediarios em sintese organica tendo especial destaque a preparacao e aplicacoes dos derivados vinilicos. Outro ambito com nascente potencial consiste no estudo de propriedades biologicas de derivados organicos contendo grupos funcionais com os atomos de Selenio ou Telurio. Os derivados hipervalentes destes compostos sao inibidores de cisteina proteases envolvidas em diversas patologias por isso sao alvos como cancer, mal de Alzheimer, e doencas causadas por parasitas (malaria, doenca de Chagas, leishmaniose, por exemplo). Para a obtencao desta classe de compostos sao descritas diversas metodologias, entretanto, alguns destes metodos requerem elevadas temperaturas e pressao, varias etapas reacionais, longos tempos reacionais, e baixos rendimentos, dificultando com isso, a sintese destes compostos. O presente estudo visa a obtencao de organocalcogenetos vinilicos derivados de acidos carboxilicos ¿¿,¿À-insaturados para o estudo de sua reatividade frente a tiois e inibicao de cisteina proteases. Embora nao tenha sido exitosa a preparacao dos derivados calcogenados, uma serie de nitro-olefinas, foi testada como inibidores de cisteina proteases e outras proteases tiol-dependentes. Os experimentos realizados permitiram a verificacao de que estes compostos sao capazes de atuarem como inibidores de cisteina proteases e de proteases cuja atividade catalitica seja dependente de tiois. / Organic chalcogenides are useful reagents and intermediates in organic synthesis with special emphasis on the applications of vinyl derivatives. Another brach of investigation lies on the study of biological properties of organochalcogenides. The study the biological properties of organic derivatives with functional groups containing selenium or tellurium atoms hypervalent derivatives of these compounds are inhibitors of cysteine proteases involved in several pathologies, therefore are targets such as cancer Alzheimer's disease bad, and diseases caused by parasites (Malaria, Chagas disease, leishmaniasis, for example). For this class of compounds are described several methods, however, some of these methods require high temperatures and pressures, various reaction steps, long reaction times and low yields, makes difficult the synthesis of these compounds. This study aims to obtain organic chalcogenides vinylic derived from á, â-unsaturated carboxylic acids to the study of his face thiol reactivity and inhibiting cysteine proteases. A series of nitro-olefins or papain was tested as inhibitors of cysteine proteases using as a template. The experiments led to the discovery that these compounds are capable of being enzyme inhibitors.

Nesta tese foram desenvolvidas metodologias sintéticas para a abertura de N-tosilaziridinas, provenientes de aminoácidos, via arilcianocupratos de ordem superior, os quais foram gerados pela reação de troca telúrio/cobre entre teluretos arílicos e cianocupratos; tais aberturas levam à formação de estruturas análogas a fenetilaminas em bons rendimentos, as quais possuem atividades farmacológicas interessantes. Adicionalmente, um conjunto de amino teluretos contendo diferentes grupos protetores foram preparados a partir dos respectivos aminoálcoois, em bons rendimentos (72 a 83%), e avaliados como potenciais espécies nucleofílicas. Os teluretos, que contêm como grupo protetor benzoíla, foram utilizados em reações de troca telúrio/lítio, gerando as espécies dilitiadas, as quais foram capturadas com diversos eletrófilos, levando à formação de aminoálcoois de cadeia maior e também à formação de análogos de fenetilaminas em bons rendimentos. Nesta tese também foram estudadas reações que envolvem química de arinos, os quais podem ser gerados de várias maneiras. Dentre essas formas para produzir os arinos, destacamos o uso de 2-(trimetilsilil)fenil triflato, o qual, na presença de fontes de íons fluoreto em solvente polar aprótico, gera a espécie reativa. Empregamos essa metodologia para geração de benzinos na reação de inserção em ligações do tipo σ de disselenetos de diarila. Tendo visto o sucesso da metodologia desenvolvida, decidimos sintetizar outros arinos derivados do 2-(trimetilsilil)fenil triflato e empregá-los em outro tipo de reação de inserção em ligações do tipo σ, desta vez em ligações entre selênio/estanho de tributil(fenilselanil)estanana, levando a uma difuncionalização nas posições 1 e 2 do anel aromático. / In this PhD thesis we developed a synthetical methodology for the ring opening reaction of N-tosyl aziridines by high order arylcyanocuprates that have been generated by tellurium/copper exchange reaction between aryl tellurides and cyanocuprates. These ring opening reactions lead to an interesting class of phenethylamines in good yields. Additionally, a set of tellurium amines containing different protecting groups were conveniently prepared in good yields (72 - 83%) from aminoalcohols and evaluated as potencial nucleophilic species. The corresponding tellurium amines have been evaluated in the tellurium/lithium exchange reaction. The nitrogen-containing organolithium compounds were efficiently prepared by using N-Bz tellurium amines and a mixture of n-butyllithium and lithium naphthalenide (LiNp) to performe the exchange reaction. The dianion intermediates were trapped with a wide range of electrophiles, resulting in this corresponding products in good to excellent yields. The reaction was also employed in the synthesis of phenethylamines. In this work we also studied reactions involving aryne chemistry, that are reactive species. A number of methods for benzyne formation have been reported in the literature. Among them we pay particular attention to the use of 2-(trimethylsilyl)aryl triflates in the presence of fluoride ion sources and aprotic polar solvents that generate this reactive species. We employed this methodology for generation of benzyne in the insertion reaction of diaryl diselenide σ bond. In view of the success of the developed methodology, we decided to synthesize other ayne derivatives from 2-(trimethylsilyl)phenyl triflate and use them on another type of σ bond insertion reaction. The insertion reaction of arynes into Se-Sn sigma bond of tributyl(phenylselanyl)stannane, leading a double functionality in the aromatic system.

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