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We report on high dispersion spectroscopy of the Ha absorption line of the cool DA white dwarf G 29 -38. This is the star for which a recently detected infrared excess has been suggested to be due to a possible brown dwarf companion by Zuckerman and Becklin (1986, 1987). Three echelle spectra obtained at the Multiple Mirror Telescope and at the Kitt Peak Mayall 4m telescope in 1987 December show no evidence for radial velocity variations larger than -'1.1 ± 8.7 km s -1 and are used to derive a weighted heliocentric radial velocity Vr = 33.7 ± 4.3 km s -1 for the white dwarf. No emission component from the hypothesized secondary star is detected. These negative results do not constitute strong evidence against the companion hypothesis, since the expected orbital velocity of the white dwarf component could be quite small, and the companion's line emission could be too faint to be detected. However, the observation of a sharp absorption line core restricts the possible rotation of the white dwarf to < 40 km s -1 and ensures that any surface magnetic field has a strength < 105 gauss. These results make it unlikely that the DA white dwarf has previously been in a cataclysmic variable accretion phase.

Desde o desenvolvimento do laser pelo norte-americano Theodore Harold Maiman em 1960, inúmeras pesquisas têm sido realizadas com o objetivo de avaliar os efeitos sobre os tecidos dentais, principalmente os relacionados com o aumento de temperatura no interior da câmara pulpar. Esta pesquisa foi desenvolvida com o objetivo de avaliar a variação de temperatura em amostras de esmalte/dentina e dentina, após irradiação com os lasers de Nd:YAG, Er:YAG (Kavo KEY Laser®) e Er:YAG (Kavo KEY Laser® 3), através de análise com termômetro de radiação infravermelha. Foram selecionados 110 terceiros molares isentos de cárie, obtidos através do Banco de Dentes Permanentes Humanos que pertence à Faculdade de Odontologia da Universidade de São Paulo e o projeto de pesquisa foi aprovado pelo Comitê de Ética em Pesquisa (CEP) com o parecer nº44/03. As coroas foram separadas das raízes por meio de um disco de carborundum e todas as coroas foram totalmente incluídas no interior de um tubo de PVC com resina transparente. Os cortes foram realizados no aparelho de corte Labcut, paralelamente ao longo eixo das coroas, no sentido mésio-distal, para obter 750 amostras, com 5 diferentes espessuras (1mm, 2mm, 3mm, 4mm e 5mm), sendo 350 amostras de esmalte/dentina e 400 amostras de dentina. Foi utilizado um termômetro de radiação infravermelha (MINIRAY 100 XL) para medição da variação de temperatura nos dois lados das amostras (frente e atrás), irradiadas em diferentes condições e parâmetros com os lasers de Nd:YAG, Er:YAG (Kavo KEY Laser®) e Er:YAG (Kavo KEY Laser® 3). Os resultados obtidos com todos os lasers e parâmetros demonstraram que a associação refrigeração + espessura das amostras foi estatisticamente significante, quanto à redução da variação de temperatura em comparação à associação ausência de refrigeração + espessura das amostras. Houve uma diminuição da variação da temperatura estatisticamente significante de acordo com as espessuras das amostras irradiadas sem refrigeração, porém não o suficiente para evitar grandes elevações de temperatura. No geral, as variações das temperaturas foram sempre maiores no lado da frente das amostras, independente do uso ou não de refrigeração. Para o laser de Nd:YAG, houve menores variações de temperatura, estatisticamente significante, nos grupos irradiados sem contato e sem a presença da tinta nanquim, independente da presença ou não de refrigeração. / The laser was developed in 1960 by Theodore Harold Maiman and many researches have been carried out with the aim to evaluate the effects on the dental tissues, mainly the effects related to the increase of temperature inside the pulp chamber. This research was developed with the purpose of evaluating the variance in temperature of the enamel/dentin and dentin samples after irradiation with Nd:YAG, Er:YAG (Kavo KEY Laser®) and Er:YAG (Kavo KEY Laser® 3) and an analysis with the infrared radiation thermometer was done. A hundred and ten teeth without dental caries were selected and obtained from the Human Permanent Teeth Bank that belongs to the Odontology College of the University of São Paulo and this research has been approved by the Ethic Research Committee (CEP), as the document n° 44/03 attests. The roots were separated from the crowns with the carburundum disc; all crowns were totally inserted inside a PVC tube with transparent resin and they were cut axially in the Labcut machine, in the mesio-distal way, to obtain 750 samples with five different thickness (1mm, 2mm, 3mm, 4mm e 5mm), 350 enamel/dentin samples and 400 dentin samples. An infrared radiation thermometer (MINIRAY 100XL) was used to measure the variance in temperature in both sides of the samples (front and behind), irradiated in different conditions and parameters with the Nd:YAG, Er:YAG (Kavo KEY Laser®) and Er:YAG (Kavo KEY Laser® 3). The results showed that the association of the refrigeration + samples’ thickness was statistically significant in the reduction of the variance in temperature when compared to the association of the refrigeration absence + samples’ thickness. There was a statistically significant reduction of the variance in temperature according to the the samples’ thickness irradiated without refrigeration, although it wasn’t enough to avoid high temperature increase. In general, the variance in temperature was always higher in the front of samples, whether there was refrigeration or not. For the Nd:YAG laser, there was a lower variance in temperature, statistically significant, in the groups that were irradiated without contact and black ink, whether there was refrigeration or not.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Este trabalho investiga a utilizaÃÃo da radiaÃÃo infravermelha como fonte de aquecimento no preparo de amostras orgÃnicas por via Ãmida visando à determinaÃÃo de elementos traÃos por ICP OES. As estratÃgias foram elaboradas com o objetivo de solubilizar e/ou digerir maiores massas de amostras. Assim, foram estudadas trÃs estratÃgias: 1) sistema IR-MW que combina o uso da radiaÃÃo infravermelha e micro-ondas, por meio de uma digestÃo prÃvia com radiaÃÃo infravermelha e posterior digestÃo no forno de micro-ondas com cavidade; 2) digestÃo parcial utilizando somente radiaÃÃo infravermelha (IR); 3) digestÃo parcial utilizando radiaÃÃo infravermelha e pentÃxido de vanÃdio (IR com V2O5) como reagente oxidante auxiliar. Diferentes procedimentos foram estudados sendo avaliados atravÃs da determinaÃÃo por ICP OES de macro e microelementos (Al, Fe, Cu, Mn, Zn, Se, Cd, Ni, Pb, Ca, K, Mg, Na e P) em diferentes tipos de leite em pÃ. O sistema IR-MW permitiu a digestÃo de massas de amostra de atà 1 g, obtendo-se boas precisÃes para a maioria dos elementos determinados. Para o procedimento IRMW A, a exatidÃo foi confirmada com material certificado Whole Milk Powder NIST 8435. Para os procedimentos IR-MW B e C foram obtidas percentagens de recuperaÃÃo variadas dependendo do elemento e da amostra. As estratÃgias IR e IR com V2O5 possibilitaram a digestÃo parcial de 2 g de amostra. A precisÃo e a exatidÃo desses procedimentos variaram de acordo com o elemento e a amostra. Todavia, a quantificaÃÃo de alguns elementos sà foi possÃvel por meio destas estratÃgias como, por exemplo, a detecÃÃo de Mn (0,30  0,01 Âg g-1 por IR; 0,35  0,01 Âg g-1 por IR com V2O5) na amostra de leite de cabra em pà integral e de Mn (1,63  0,02 Âg g-1 por IR; 1,78  0,06 Âg g-1 por IR com V2O5) na amostra de leite em pà desnatado nÃo enriquecido. O uso do V2O5 foi essencial na quantificaÃÃo de Fe (0,54  0,13 Âg g-1) no leite de cabra em pà integral. De uma maneira geral, dependendo do elemento e de seu teor na amostra, sua determinaÃÃo por ICP OES sà à possÃvel quando se usa maiores quantidades de massa de amostra. O emprego da radiaÃÃo infravermelha no auxilio de digestÃo de maiores massas de amostra à uma alternativa para laboratÃrios que utilizam apenas forno de micro-ondas com cavidade. / In this work it was investigated the use of infrared radiation as heating source in the preparation of organic samples aiming the determination of trace elements by ICP OES. The strategies were developed in order to solubilize and / or digest larger masses of samples. Thus, three strategies were studied: 1) IR-MW system which combines the use of infrared radiation and microwave through a previous digestion with infrared radiation and subsequent digestion in the oven microwave cavity; 2) partial digestion using only infrared radiation (IR); 3) partial digestion using infrared radiation and vanadium pentoxide (IR with V2O5) as auxiliary oxidizing reagent. Various procedures were studied and the efficiencies were evaluated by the determination of macro-and microelements (Al, Fe, Cu, Mn, Zn, Se, Cd, Ni, Pb, Ca, K, Mg, Na, and P) in milk samples by ICP OES. The IR-MW system allowed the digestion of sample masses of up to 1 g, to obtain good precision for most of the elements determined. For the IR-MW A procedure the accuracy was confirmed with certified material of whole milk powder NIST 8435. For the IR-MW B and C procedures were obtained recovery rates varied depending upon the element and the sample. Strategies IR and IR with V2O5 allowed the partial digestion of 2 g of sample. The precision and accuracy of these procedures varied according to the element and the sample. However, the determination of some elements was only possible using these strategies, for instance, the detection of Mn (0.30  0.01 Âg g-1 by IR; 0.35  0.01 Âg g-1 by IR with V2O5) in the goat whole milk powder sample of and Mn (1.63  0.02 Âg g-1 by IR; 1.78  0.06 Âg g-1 by IR with V2O5) in the non-fat milk powder not enriched sample. The use of V2O5 was essential in the quantification of some elements such as Fe (0.54  0.13 Âg g-1) in goat milk powder samples. In general, the determination of trace elements by ICP OES is only possible using larger amounts of sample, depending on the element and its content in the sample. The use of infrared radiation to accomplish the digestion of larger masses of samples is an alternative to using only laboratory microwave oven cavity.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 361-380).

In this thesis work, temperature estimation algorithms based on physical and radiometric approaches are developed. Developed algorithms, firstly, tested on artificial images for different test cases. Following this, algorithms are tried out on real infrared images in order to verify that they are working properly. Finally, temperature estimations are done by including emissivity. Obtained results are compared to the temperature estimation results of a reference infrared camera. All the results and errors obtained during this study are presented and discussed.

Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Ceramic and Materials Science and Engineering." Includes bibliographical references.

Thesis (M.S.)--Florida State University, 2006. / Advisor: Xiaolei Zou, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed June 13, 2006). Document formatted into pages; containsxi, 65 pages. Includes bibliographical references.

Indium antimonide (InSb) and gallium antimonide (GaSb) are technologically important III-V semiconductor materials used in infrared detector systems. Yet, the application of these materials is to a certain extent limited, in that the techniques currently used for their growth are both expensive and problematic. Semiconductor electrochemical deposition, which has been successfully applied to the generation of II-VI semiconductor materials, may offer the prospect of overcoming such limitations. This work presents results that represent a significant contribution to the development of electrochemical methods for both InSb and GaSb thin film growth. The direct electrochemical co-deposition of InSb was achieved via the potentiostatic electrolysis of aqueous halide/citric acid electrolyte solutions, and for the first time, non-aqueous (ethylene glycol) electrolyte solutions containing the halides and tetraethylammonium chloride. This choice of solvents allowed the compound's deposition to be studied over a wide range of temperatures (RT to 185 &deg;C). A first report was also made of the direct potentiostatic co-deposition of GaSb from an aqueous solution containing Ga[2](SO[4])[3] and SbCl[3].An extensive study was carried out on the relationship between the technique's fundamental growth parameters (temperature, deposition potential, solution composition etc.) and the film's compositional, crystallographic and morphological properties. The material's characterisation showed that there was tendency for the films to be non-stoichiometric. X-Ray diffraction patterns obtained from InSb films deposited from aqueous electrolyte solutions showed them to generally consist of two phases, the compound and, depending mostly on deposition potential, one of the elements. Films containing three phases, the compound and both elements, were deposited on Ti substrates from aqueous solutions and on to ITO substrates from non-aqueous solutions. These results were interpreted from both thermodynamic and kinetic viewpoints. This led to the conclusion that kinetic barriers to the formation of InSb still existed, even at the highest temperature used (~185 &deg;C). In respect of GaSb, the compound's formation was complicated by a side reaction involving the evolution of H[2].New studies involving Scanning Electron Microscopy of the electrodeposited materials showed that they exhibited a nodular morphology, which can be explained in terms of the film's limiting current growth conditions. Energy Dispersive X-Ray Analysis (EDX) and Glow Discharge Optical Emission Spectroscopy (GDOES) identified indium chloride as a major impurity in the InSb films, especially those deposited from non-aqueous solutions. A mechanism for the incorporation of indium chloride was proposed, based on the physical entrapment of a precipitate of the compound.

The objectives of the research undertaken have been to investigate the properties of semiconductor lasers operating at around 1.3 mum. The aim of the investigation is to suggest modifications which give rise to improved operating characteristics especially in the high temperature (approaching 85 &deg;C) range. The investigation can be divided into 2 sections: a theoretical approach and an experimental section. The theoretical study examined the performance of compressively strained InGaAsP/InP multiple quantum-well lasers emitting at 1.3 mum in order to investigate the important factors and trends in the threshold current density and differential gain with strain, well width and well number. Structures with a fixed compressive strain of 1% but variable well width, and also with a fixed well width but variable strain from 0% to 1.4% have been considered. It has been found that there is little benefit to having compressive strains greater than 1 %. For structures with a fixed 1% compressive strain and unstrained barriers, an optimum structure for lowest threshold current density and a high differential gain has been found to consist of six 35 A quantum-wells. In addition, compensated strain (CS) structures with compressive wells and tensile barriers have been examined. It is shown that the conduction band offset can be significantly increased and the valence band offset reduced in such structures, to give band-offset ratios comparable with aluminium based 1.3 mum devices. The gain calculations performed suggest that there is little degradation in the threshold carrier density or differential gain due to these alterations in the band offsets; and hence a better laser performance is expected due to a reduction in thermal leakage currents due to the improved electron confinement. The experimental study concentrates on looking at certain key design parameters to investigate their effect on the laser performance. These design parameters range from the number of quantum-wells to the device length. The experimental study confirms the conclusions drawn in the theoretical investigation that the optimum structure for a 1.3 mum InGaAsP laser for low threshold current, high efficiency and high characteristic temperature operation consists of six 1% compressively strained 50 A quantum-wells in a device of medium length (approx. 450 mum). The inclusion of a high reflection coating on one facet provides further improvement in the device performance, but increases the production cost dramatically. Also investigated in the experimental section is the effect of changing the device material from InGaAsP to InGaA1As. The results discussed do not offer firm evidence of any improvement in the device characteristics in switching from a P-based to an Al-based structure. This is mainly due to the added complication of switching to a RWG structure from a BH structure. Another explanation for the relatively poor performance of InGaAsP 1.3 mum lasers has been examined. That is leakage of the carriers out of the well region. Evidence of a leakage current has been seen primarily in devices with a low number of quantum-wells. A novel measurement technique has been demonstrated, which should prove useful for obtaining a numerical value for the leakage current in semiconductor lasers. The results presented suggest that leakage current is not significant for a 9 well device until operating at temperatures above around 373 K. This is supported by evidence supplied by the spontaneous emission spectra.