81 |
Impurity and Back Contact Effects on CdTe/CdS Thin Film Solar CellsZhao, Hehong 05 December 2007 (has links)
CdTe/CdS thin film solar cells are the most promising cost-effective solar cells. The goal of this project is to improve the performance for CdS/CdTe devices by improving the open circuit voltage Voc and current density Jsc. Efforts focused on increasing the Voc, which include increasing the doping concentration by introducing Phosphorus and Antimony, finding and testing new back contact materials, and varying the ambient of CSS CdTe. In addition, the effect of Zn2SnO4 on the cells' performance was also studied.
Electrical characterization of the thin films and completed devices were carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V), and Spectral Response (SR) measurements. Structural/chemical characterization was done by SEM, XRD and EDS analysis.
The ambient of CSS CdTe affects the growth rate, the grain size and electronic properties of CdTe. The N2/O2 mixture with varied ratio (N2/O2=9/1, 7/3, 5/5 and 1/9) was used in this study. The cells' performance and the net carrier concentration were studied as a function of the N2/O2 ratio. The net carrier concentration increases with the increasing O2 concentration.
The extrinsic impurities (P and Sb) were incorporated into CdTe layer. Phosphorus was directly introduced into CSS CdTe source. The Sb was incorporated into CdTe by a diffusion process. The effects of the annealing parameters, the excess Sb on CdTe surface, the CdCl2 treatment and the depth of Sb in CdTe were studied. Higher doping concentration up to 1016 cm-3 has been achieved, however, Voc is still in the range of 830 mV.
|
82 |
Determination of antimony in water, beverages, and fruitsXia, Yunlong 06 1900 (has links)
Antimony is naturally occurring in the environment. The assessment of human exposure to environmental antimony is limited. This research focuses on the determination of antimony in water, beverages, and fruit.
First, we explored whether there is a correlation between arsenic and antimony in water samples with a wide range of arsenic and antimony concentrations. The results showed absent correlation.
Second, we determined antimony concentrations in bottled beverages including bottled water, soft drinks, juices and alcoholic drinks from Canada. The results showed that the antimony in most of these samples were below the Health Canada Guideline (6 g/L) for drinking water except one alcoholic drink which contains 7 g/L antimony.
Further analysis of lemons and oranges using high performance liquid chromatography (HPLC) separation and inductively coupled plasma mass spectrometry (ICP-MS) detection demonstrated the presence of antimonycitrate species in these fruits, which has not been reported in literature.
|
83 |
Analyse des Antimon-Resistenzmarkers ARM58 aus Leishmania infantumSchäfer, Carola 23 July 2013 (has links) (PDF)
Antimonpräparate sind seit über 60 Jahren der Standard zur Behandlung der Leishmaniose. Immer
häufiger kommt es jedoch zum Therapieversagen durch resistente Erreger. In Indien sprechen über
60 % der erstmalig mit Antimonpräparaten behandelten Patienten nicht mehr auf die Therapie an
(Sundar et al., 2000). Obwohl dies ein großes Problem darstellt, ist bisher wenig über die
Resistenzmechanismen der Parasiten bekannt. Durch die Aufklärung dieser Mechanismen könnten
zwei Hauptziele erreicht werden:
i) Es könnten optimierte Medikamente entwickelt werden, die die Resistenzmechanismen der
Parasiten umgehen.
ii) Es könnten diagnostische Maßnahmen ergriffen werden, um vor Beginn einer Therapie deren
Erfolgschancen zu kalkulieren. So würde man dem Patienten die starken Nebenwirkungen sowie
die Kosten der Antimontherapie ersparen. Desweiteren könnte sofort mit einer wirkungsvollen
Therapie begonnen und somit die Zeitspanne verkürzt werden, in der der infizierte Patient ein
Reservoir für die weitere Transmission der Parasiten darstellt.
In Vorarbeiten wurde durch genetische Komplementation das Gen LbrM20_V2.0210 (Lbr_0210)
vorläufig identifiziert, das bei Überexpression Antimonresistenz vermittelt (Dissertation A. Nuehs,
2010). Diese Arbeiten wurden mit Leishmania braziliensis durchgeführt. Direkt benachbart befindet
sich ein strukturell sehr ähnliches Gen, LbrM20_V2.0200 (Lbr_0200). Beide Gene wurden bei den
vorangegangenen Sb(III)-Selektionen untersucht. Hierbei konnte ausschließlich Lbr_0210 als
resistenzvermittelnd identifiziert werden. Datenbankrecherchen ergaben, dass es zu Lbr_0210 je ein
direktes orthologes Gen in Leishmania infantum und Leishmania major gibt. Das Ziel des ersten
Teils dieser Doktorarbeit war es, die resistenzvermittelnde Funktion des zu Lbr_0210 orthologen
Gens aus L. infantum, LinJ34.0220, in unterschiedlichen Leishmania-Spezies zu verifizieren. Es
war vor allem wichtig die Frage zu beantworten, ob das Gen auch im pathogenen Stadium des
Parasiten, also in intrazellulären Amastigoten, Resistenz gegenüber Pentostam®, einem
Standardmedikament, vermittelt. Im zweiten Teil dieser Arbeit sollte das Protein strukturell und
zellbiologisch charakterisiert werden, um Hinweise auf den Resistenzmechanismus zu erhalten.
Durch den Vergleich mit dem zu Lb_0200 orthologen Gen aus L. infantum, LinJ34.0210, sollten
Hinweise auf die unterschiedlichen Aufgaben der Proteine gesammelt werden.
|
84 |
Electrochemical Deposition of Bismuth Telluride and Antimony Telluride Thin Films for Micro TE-cooler ApplicationsLi, Ming-chan 13 July 2006 (has links)
¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@Abstract
This paper presents an integrated batch-produced (Bi, Sb)2Te3 micro thermoelectric cooler(£g-TEC) fabricated by electrochemical MEMS technology. To optimize the thermal conductivity of (Bi, Sb)2Te3 thin layers, a cathode with tunable rotary speed has been designed in the electroplating system to well control the thin film deposition rate and uniformity.The column-type micro thermoelectric thin films fabricated using electrochemical-deposited and patterned using photolithography processes. The thermoelectric thin films made of N-type Bi2Te3 and P-type Sb2Te3 with an average thickness of 5£gm, are connected using Cr/Au layers at the hot junctions and cold junctions. The measured Seebeck coefficient and electrical resistivity of the thermoelectric thin films,are -52£gV/K and 2.52¡Ñ10-5£[m(N-type, power factor of 0.11mW/K2m),and 71£gV/K and 1.91¡Ñ10-5£[m( P-type, power factor of 0.26mW/K2m) after annealing at 250¢J.Under the circumstances that voltage of 2-5 volts is driven, the upper and lower levels electrode shows tentatively that there is 0.7¢Jof difference in temperature.
|
85 |
Design and Fabrication of Bi2Te3/Sb2Te3 Micro TE-coolerShe, Kun-dian 12 September 2007 (has links)
This paper presents an integrated column-type micro thermoelectric cooler (£g-TEC) constructed with serial connected p-type antimony-tellurium (Sb2Te3) and n-type bismuth-tellurium (Bi2Te3) micro pillars deposited by electrochemical deposited technology. To optimize the power factor, density and uniformity of the TE films and to enhance the reproducibility of £g-TEC device, a cathode with tunable rotary speed and
with accurate current controller has been designed in the electroplating system of this research.
The electroplating deposited Bi2Te3 and Sb2Te3 with an average thickness of 8 £gm, are connected using Cr/Au layers at the hot junctions and cold junctions. The measured Seebeck coefficient and electrical
resistivity are -86 £gV/K and 16 £g£[-m for Bi2Te3 films after annealed at 250¢XC, and are 68 £gV/K and 30 £g£[-m for Sb2Te3 films after annealed at 200¢XC. The optimized power factors of the n-type (2.64¡Ñ10-4 W/K2m) and p-type (2.64¡Ñ10-4 W/K2m) telluride compounds have been demonstrated in this paper. Under 5 volts driven, the integrated £g-TEC device shows average cooling achieved is about 1.3 ¢XC.
|
86 |
Archaea at the El Tatio Geyser Field : community composition, diversity, and distribution across hydrothermal features and geochemical gradientsFranks, Megan A. 11 July 2012 (has links)
Methanogenesis, a metabolic pathway unique to Archaea, is severely inhibited by the reduced form of arsenic (As). Despite this inhibition, methanogenic Archaea are present in some hydrothermal features at the El Tatio Geyser Field (ETGF), a high-arsenic site with 100+ hydrothermal features, including boiling pools, geyers, fumaroles, and springs. The ability of methanogenic Archaea and other microorganisms to withstand elevated arsenic concentrations, and a variety of other extreme environmental conditions at ETGF, may be due to unique adaptations or syntrophic relationships with other microorganisms.
ETGF is situated in the Andes Mountains at an altitude of ~4300 meters. UV radiation is elevated in this region and air temperatures fluctuate widely. Most hydrothermal waters discharge at ~85˚C, the local boiling point, and rapidly evaporate due to the arid climate. This concentrates hydrothermal salts and metals, including arsenic (As) and antimony (Sb). Additionally, dissolved inorganic carbon (DIC) concentrations are extremely low in most features and may limit life.
Water chemistry analyses done for this study show variability in dissolved constituents between features that are consistent over time. Variations may be due to the source or residence time of waters, and differences in chemistry could be responsible for the presence or absence of methanogenic Archaea at hydrothermal sites. The overlying control on microbial diversity and community composition may be water geochemistry, and potentially specific constituents.
The goals of this study were to detect novel microbial taxa at ETGF, including novel methanogens, as well as to document microbial community composition at select hydrothermal features. The distribution and diversity of microorganisms at each feature was analyzed phylogenetically and within an ecological context in order to determine physicochemical and biological controls on community composition. Additionally, a model methanogen was used in laboratory analyses to determine how concentrations and oxidation states affected growth and methane production. This methanogen, Methanothermobacter thermautotrophicus, is found at ETGF, Yellowstone, and other hydrothermal fields, and thrives in high-temperature environments.
MPN (most probable number) analyses show that culturable biomass from multiple sites contain metabolically active methanogens. These results support the biogenicity of dissolved methane detected in the field. 16S rRNA surveys of Archaea at four sites show that Archaea are diverse, and archaeal community composition varies across features. Phylogenetic tree construction indicates that Archaea from ETGF group together, suggesting that the isolation and broad environmental constrains on ETGF have some control on phylogenetic diversity.
Laboratory analyses of As and Sb concentrations on M. thermautotrophicus suggest that Sb may decrease the inhibition of methanogenesis by As by preventing the formation of As(III) from As(V). Statistical analyses correlating microbial community composition and structure to physicochemical parameters show that archaeal and bacterial communities relate to different variables; with Bacteria correlating to water temperature, and Archaea correlating to dissolved constituents such as hydrogen gas and sulfate. / text
|
87 |
Determination of antimony in water, beverages, and fruitsXia, Yunlong Unknown Date
No description available.
|
88 |
Tin, Antimony, Bismuth, and Tellurium Lewis Acids in sigma-Accepting Ligands for Transition MetalsLin, Tzu-Pin 2012 August 1900 (has links)
The interactions between ligands and transition metals have been an essential subject in inorganic chemistry. Other than the commonly known L-type (two-electron donors) and X-type ligands (one-electron donors), Z-type ligands (two-electron acceptors) have begun to surface in the past decade. Capable of drawing a pair of d-electrons away from a metal, Z-ligands affect the electronic structures of transition metals leading to fascinating properties as well as reactivity. In particular, recent advance in Z-ligand chemistry have resulted in the discovery of transition metal borane complexes featuring metal → boron interactions. Owing to the presence of a metal → boron interaction which stabilizes the low valent state, these complexes have been shown to activate small molecules such as H2, CO2, and CHCl3. Further, the concept of Z-ligand has been extended to s- and d-block Lewis acids. In spite of these achievements, Z-ligands that contain Group 14-16 elements as Lewis acids remain scarce and relatively unexplored.
For this reason, we have launched a series of investigations targeting complexes with transition metal → Group 14-16 interactions. These investigations have allowed us to synthesize a series of novel complexes with palladium, platinum, or gold as metallobasic late transition metals and tin, antimony, bismuth, and tellurium as Lewis acids. The transition metal → Lewis acid interactions of these complexes, which are supported by o-phosphinophenylene, 1,8-naphthalenediyl or 8-quinolinyl buttresses, have been established experimentally and theoretically. Further, the reactivity of these complexes toward anions and oxidants has also been explored. These experiments have led to the discovery of tellurium-platinum complexes that sustain reversible two-electron redox processes including the photo-reductive elimination of chlorine. Other noteworthy outcomes of this research include the isolation of the first telluroxanyl-metal complex as well as the discovery of complexes with HgII → SbV interactions.
|
89 |
Evaluation of Bi2O3 and Sb6O13 as oxidants for silicon fuel in time delay detonatorsKalombo, Lonji. January 2005 (has links)
Thesis (M.Sc)(Chemical Technology, Engineering and Technology Management)--University of Pretoria, 2005. / Includes summary. Includes bibliographical references (leaves 75-80).
|
90 |
Electron diffraction studies of unsupported antimony clusters : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physics in the University of Canterbury /Kaufmann, Martin January 2006 (has links)
Thesis (Ph. D.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.
|
Page generated in 0.0311 seconds