Glass-ceramic composites and nanocrystalline glass-ceramics containing barium titanate (BT) or potassium sodium niobate (KNN) ferroelectric phases have been studied, with particular regard to their use as dielectric energy storage materials. Barium borosilicate glass (BBS) was used as a sintering aid for BT and KNN, producing glass-ceramic composites. The temperatures required to achieve densification were reduced from 1400 to 1200 °C for BCZT (Ca, Zr-doped BT) and 1170 to 1050 °C for KBN (Bi, Na, K, Zr-doped KNN) by the use of glass additives. An unexpected observation, found in both BCZT and KBN systems, was the heterogeneous dissolution of dopant elements into the glass, inducing additional anomalies in the relative permittivity-temperature relationships. For BCZT, the orthorhombic-tetragonal phase transformation temperature shifted upwards to ≈ 50 °C, which was attributed to modification of the Ca/Zr ratio by preferential dissolution of Ca into the glass phase. Similarly, for KBN the dopant elements appeared to be leached into the liquid phase during sintering, resulting in relative permittivity-temperature characteristics similar to those of pure KNN. A modified BBS glass having various KNN contents was prepared by the conventional melt-quenching method and then heat-treated to induce crystallisation, producing nanocrystalline glass-ceramics. It is shown that crystallisation of an intermediate barium niobate phase initiates at temperatures in the region of 650 °C; this is subsequently converted into perovskite KNN together with a second phase of Ba3Nb5O15 at temperatures from 700 to 800 °C. The final crystallite size was in the region of 30±7 nm. The highest dielectric energy storage density of 0.134(4) J cm-3 was obtained for a glass-modified BT ceramic at an electric field level of 5 kV mm-1. However, the energy storage efficiency of the BT-based ceramics was relatively poor and they displayed a general tendency for saturation, indicating potentially poor performance at higher field levels. On the other hand, the KNN-based ceramics exhibited slightly lower energy storage density values, up to 0.108(1) J cm-3, but with much improved linearity and energy storage efficiency. Therefore, the latter is considered to be more suitable as energy storage dielectrics. The BBS-KNN glass-ceramics yielded relatively low energy storage density, 0.035(2) J cm-3, but the dielectric linearity and storage efficiency were similar to or better than those of the KNN ceramics, indicating good potential for use as energy storage dielectrics at very high electric field levels as a result of their nanocrystalline microstructures.

Peats and organic-rich soils are a key part of the global carbon (C) cycle due to their sequestration and storage of atmospheric C as organic matter. Atmospheric deposition as a result of human activities has led to increased inventories of lead (Pb) and mercury (Hg) in UK peats and organic-rich soils. Ombrotrophic peat bogs, which receive all their nutrients and pollutants from the atmosphere, provide a historic record of Pb and Hg deposition within their solid phase. Organic-rich forest soil systems can also act as sinks for anthropogenic Pb but vertical transport of Pb can distort these temporal records. The long-term outlook may, however, be affected by processes which lead to decomposition of organic matter e.g. drying out of peatlands and soils due to climatic change, since these may release Pb into the aqueous phase and volatile Hg to the atmosphere. The associations and speciation of Pb and Hg within peats and organic-rich soils are not well understood but are key to understanding both the potential for release of these pollutants into other environmental compartments and the risks to ecosystems and human health posed by such a release. Investigation of 4 sites in central Scotland showed that, depending on vertical depth, ~40-99% of Pb in ombrotrophic peat was in association with large (0.22 μm – 100 kDa) humic molecules. Near-surface regions where intact plant material had not yet undergone complete humification showed the lowest proportion of Pb-humic association. Historical Pb deposition was retained to similar degrees across each site with recorded inventories to 1986 of 0.340-0.561 g m-2. However, perturbation of the 206Pb/207Pb isotope ratio profile at Glentress forest indicated that limited migration of petrol-sourced Pb may be occurring. Similarly, perturbation of the 210Pb profile at Auchencorth Moss, in addition to discrepancies in the apparent time period in which peak Pb deposition occurred, indicated that Pb may also be subject to migration within this ombrotrophic system. With respect to Hg, between-site differences in speciation were observed. For example, Hg2+ represented < 25% of the total Hg species in the top 10 cm of solid phase ombrotrophic peat but > 50% of the total in forest soil. In contrast, aqueous phase Hg was entirely in the inorganic form across all sites. The occurrence of a solid phase [Hg] peak in layers corresponding to the ~1955 height of coal burning, in addition to the narrow range of peatland Hg inventories to 1950 (2.20-3.23 g m-2) provide evidence that Hg deposition records may be maintained in organic-rich systems to a greater degree than previously assumed. Differences observed in the associations of Pb and the speciation of Hg between the surface vegetation of ombrotrophic bogs and the underlying peat suggests that plants play an integral role in the biogeochemical behavior and sequestration of Pb and Hg in these terrestrial systems.

As cirurgias radioguiadas, utilizando sondas com detectores de radiação, têm sido destaque na área médica na última década. Esta técnica consiste na marcação de lesões com uma substância radioativa, que injetada no paciente, concentra-se no tumor e auxilia a sua localização durante o ato cirúrgico. Entre as cirurgias radioguiadas, a identificação e exame do linfonodo sentinela, tem revolucionado a conduta de neoplasias em estádio inicial, quando estas estão sendo disseminadas pela via linfática. As condições impostas por uma cirurgia e a proximidade entre alguns linfonodos, exige das sondas, reduzidos diâmetros e capacidade de identificação individual destes linfonodos marcados com um radiofármaco. O mercado internacional fornece sondas adequadas com cristais cintiladores e com semicondutores de telureto de cádmio, CdTe, mas que algumas vezes carecem de uma pronta assistência técnica no mercado brasileiro devido a todo o conjunto ser importado. Este trabalho desenvolveu sondas com tecnologia nacional, utilizando cristais cintiladores de iodeto de césio dopado com tálio, CsI(Tl) e, em substituição aos cristais semicondutores de CdTe, o cristal de brometo de tálio, TlBr que é um meio semicondutor detector em desenvolvimento mundialmente, com vantagens em relação ao CdTe. Ambos os cristais utilizados foram crescidos no IPEN. Toda a eletrônica necessária, e em especial, o pré-amplificador, que constituía também um fator limitante para desenvolvimento destes tipos de sonda no país, foram desenvolvidos com componentes encontrados no mercado nacional. Medidas sistemáticas de resolução espacial, seletividade espacial, sensibilidade máxima e qualidade da blindagem foram realizadas para as sondas desenvolvidas. Os resultados mostraram que dois modelos de sonda, uma com o cristal de CsI(Tl) e outra com o semicondutor de TlBr atenderam as qualidades sugeridas pela literatura internacional para sondas cirúrgicas radioguiadas. / Radioguided surgery, using probes with radiation detectors, has been prominence in the medical area in the last decade. This technique consists in injecting a radioactive substance to concentrate in tumour and assist the localization during the surgical procedure. The radioguided surgeries allowing the identification of lymph node has revolutioned the behavior of tumour in initial stadium when are being spread by lymphatic way. The conditions imposed to the surgery due the proximity between some lymph nodes, demands of the probes, a small diameters and capacity of individual identification of these lymph nodes radiolabelled by a specific tracer. The international market supplies these probes with CdTe semiconductors and scintillators, but there is some time lack a promptly technical assistance in the Brazilian market. This work developed probes with national technology, using CsI(Tl) scintillators crystals and, in substitution to CdTe crystals semiconductors, the TlBr crystal, that is a new semiconductor detector in a world-wide development, with advantages in relation to the CdTe. Both crystals have been grown in IPEN. All the necessary electronics, specially, the preamplifier, that was also a restrictive factor for development of these types of probe in the country, have been developed with components found in the national market. Systematic measures of spatial resolution, spatial selectivity, maximum sensitivity and quality of the shielding have been carried the probes development. The results have shown that the probes, one with the CsI(Tl) crystal and another with TlBr semiconductor presented the requested performance in the international literature for radiguided probes.

Review of Lead Belly: The Smithsonian Folkways Collection

The differential lead-zinc flotation process has been practised since 1912, yet selectivity in the process remains a significant technical issue in many operations. The minerals processing operation at Zinifex Limited's Century Mine, which uses differential flotation, began in November 1999 and the flotation behavior of the ore remains a major research interest. The present study was aimed to determine the possible mechanisms of sphalerite recovery during carbon pre-flotation and lead flotation in this operation including identification of the variables that affect these two flotation stages and also identify depressants for sphalerite that offer better selectivity during these stages. To achieve this aim, the study was undertaken in two stages: a review of literature related to selectivity during lead-zinc flotation, and an experimental program consisting of bench-scale flotation tests wherein the various experimental variables were systematically varied. A comparison between the data generated to those of the plant was also undertaken. The review of literature revealed four basic mechanisms of sphalerite recovery: activation of the sphalerite surface, composite particle flotation with galena and gangue, graphitic inclusions in the mineral surface and entrainment in the froth. The depression or rejection of sphalerite on the other hand could be affected by grinding, froth washing and the use of chemical depressants including cyanides, zinc sulfate, abraded iron and iron sulfate, sodium sulfide, sodium sulfite and metabisulfite, and organic depressants derived from selective collectors. / The results from the experimental program indicate that: (a) activation of the sphalerite surface as a mechanism of sphalerite recovery during lead flotation was not significant at the Century Mine concentrator, (b) the recovery of sphalerite during the carbon pre-flotation was predominantly due to a bulk flotation action and entrainment in the froth, (c) composite particle recovery was a significant contributing factor in the recovery of sphalerite in lead flotation, and (d) mineral oxidation was only significant for galena and occurred mostly during pre-flotation, but the use of cyanide adequately counters any effect on sphalerite recovery. The investigation on the variables that affect the pre-flotation and lead flotation circuits revealed that: (a) reducing the pulp density and the amount of frother added during pre-flotation significantly reduced the bulk flotation action and entrainment of sphalerite in the froth, b) grinding the ore finer (P80 = 40 μm) reduced the recovery of sphalerite as composite particles during lead flotation, and (c) the pulp pH was best maintained at natural pH during pre-flotation and at an elevated alkaline pH (pH 9.5) during lead flotation for optimal selectivity. In terms of depressants it was found that zinc sulfate specifically depressed sphalerite during lead flotation.

<p>Generation IV (Gen IV) is a developing new generation of nuclear power reactors which is foreseen to bring about a safer and more sustainable production of nuclear power. A Swedish research program called GENIUS aims at developing the Gen IV technology, with emphasis on lead-cooled fast reactors. The present work is part of the GENIUS project, and deals with safeguards aspects for an envisioned future 100 MW Gen IV demonstration facility including storage and reprocessing plant. Also, the safeguards licensing aspects for the facilities have been investigated and results thereof are presented.</p><p>As a basis for the study, the changed usage and handling of nuclear fuel, as compared to that of today, have been examined in order to determine how today's safeguards measures can be modified and extended to meet the needs of the demonstration facility. Safeguards approaches have been considered for within and between each unit at the demonstration facility, with the main focus on system aspects rather than proposing safeguards instrumentation on a detailed level.</p><p>The proposed safeguards approach include the implementation of well-tried measures that are used at currently existing nuclear facilities as well as suggestions for new procedures. The former include, among others, regular inventory verifications, containment and surveillance measures as well as non-destructive and destructive measurements of nuclear materials. The traditional approaches may be improved and supplemented by modern techniques and approaches such as nuclear forensics, safeguards-by-design and improved on-line monitoring of streams of nuclear material. The safeguards approach for the demonstration facility should be outlined early in the licensing process, such that the facility units can be designed in a way that allows for implementation of adequate safeguards measures with minimal intrusion on the regular activities.</p><p>For operating a nuclear facility in Sweden, two separate permits are required. A license application for a new facility shall be handed both to the Swedish Radiation Safety Authority and to the environmental court, which in parallel prepare for decisions according to the Nuclear Activities Act and the Environmental Code, respectively. In terms of the Swedish legislation, there are no fundamental differences between Gen IV facilities and currently existing plants. However, comprehensive investigations and evaluations would be required in order to license new Gen IV facilities.</p>

Thesis (Ph. D.)--University of Rhode Island, 2005. / Typescript. Includes bibliographical references (leaves 120-131).

Generation IV (Gen IV) is a developing new generation of nuclear power reactors which is foreseen to bring about a safer and more sustainable production of nuclear power. A Swedish research program called GENIUS aims at developing the Gen IV technology, with emphasis on lead-cooled fast reactors. The present work is part of the GENIUS project, and deals with safeguards aspects for an envisioned future 100 MW Gen IV demonstration facility including storage and reprocessing plant. Also, the safeguards licensing aspects for the facilities have been investigated and results thereof are presented. As a basis for the study, the changed usage and handling of nuclear fuel, as compared to that of today, have been examined in order to determine how today's safeguards measures can be modified and extended to meet the needs of the demonstration facility. Safeguards approaches have been considered for within and between each unit at the demonstration facility, with the main focus on system aspects rather than proposing safeguards instrumentation on a detailed level. The proposed safeguards approach include the implementation of well-tried measures that are used at currently existing nuclear facilities as well as suggestions for new procedures. The former include, among others, regular inventory verifications, containment and surveillance measures as well as non-destructive and destructive measurements of nuclear materials. The traditional approaches may be improved and supplemented by modern techniques and approaches such as nuclear forensics, safeguards-by-design and improved on-line monitoring of streams of nuclear material. The safeguards approach for the demonstration facility should be outlined early in the licensing process, such that the facility units can be designed in a way that allows for implementation of adequate safeguards measures with minimal intrusion on the regular activities. For operating a nuclear facility in Sweden, two separate permits are required. A license application for a new facility shall be handed both to the Swedish Radiation Safety Authority and to the environmental court, which in parallel prepare for decisions according to the Nuclear Activities Act and the Environmental Code, respectively. In terms of the Swedish legislation, there are no fundamental differences between Gen IV facilities and currently existing plants. However, comprehensive investigations and evaluations would be required in order to license new Gen IV facilities.

Lead is an omnipresent pollutant, and its contamination in natural waters is an issue of current regulatory concern throughout the world including Canada. The free divalent ion of lead (Pb2+) is considered to be the most bioavailable and toxic form of lead. Pb2+ is known to be a calcium antagonist in vertebrates including fish. It is believed that lead causes toxicity to freshwater fish primarily by disrupting ionic homeostasis both during acute and chronic waterborne exposure. Lead can also potentially act as a respiratory toxicant since it is known to impair hemoglobin synthesis in both vertebrates. To date, the mechanistic underpinnings of lead accumulation and toxicity in aquatic invertebrates are not well understood, particularly during acute exposure. Therefore, the main objectives of the present study were in two folds: (i) to investigate the mechanisms of waterborne lead uptake, and (ii) to understand the physiological basis of lead toxicity during acute exposure. I used freshwater crustacean, <i>Daphnia magna</i>, as a model freshwater invertebrate species for my study. <i>Daphnia</i> are known to be quite sensitive to metals and widely used as a model species for toxicity assessments. The results of my study suggest that lead inhibits waterborne Ca2+ uptake in <i>Daphnia</i> in a concentration dependent manner, and this inhibition occurs predominantly through a direct competitive interaction. The entry of waterborne Pb2+ in <i>Daphnia</i> likely occurs via both lanthanum-sensitive and verapamil-sensitive epithelial calcium channels. Moreover, my results also indicate that acute waterborne lead exposure severely disrupts both Ca2+ and Na+ uptake from water, which are concomitant with the increase in the lead body burden in <i>Daphnia</i>. Interestingly however, acute exposure to lead does not affect the rate of oxygen consumption in <i>Daphnia</i>, indicating no acute respiratory toxicity of lead. Overall, it appears that lead acts as an ionoregulatory toxicant to <i>Daphnia</i> during acute waterborne exposure.

Due to the introduction of Restriction of Hazardous Substances (RoHS) directive Pb containing solders have been banned from the electronics industry and a reliable replacement for the Sn-Pb solder is being sought for by industry around the globe. Medical and Defense industries are currently exempt from the directive and use Sn-Pb solder in their manufacturing process. The switch to lead-free has led component manufacturers to use different lead-free solders, thus causing mixed solder joints of lead-free components with Sn-Pb paste. In this study, mixed assembly microstructures and mechanical properties were examined. Furthermore, six novel lead-free solders were prepared using SAC105 solder doped with elements: Ti, Ni, Mn, La, Ce and Y. The solidification microstructures, fracture behavior and wetting properties of these solders were evaluated to find a suitable replacement for SAC105 solder.