This work aims to study the variation in electrical and optical properties of nanoscale Schottky diodes by varying their dimensions in the nanoscale. Experimental conditions for fabricating porous alumina with varying pore diameters and inter-pore distances were first optimized by anodizing Aluminum tape with variable currents. Cadmium Sulfide nanowires were then synthesized inside the membranes by dc electrodeposition. Finally a high work function metal was deposited on top as a contact for the metal-semiconductor Schottky diode junction. As a comparative study, Schottky diodes fabricated using the same metals and Cadmium Sulfide thin films deposited on conducting glass substrates using electro-deposition and annealed in different ambient were also studied. Device characterizations were carried out by field-emission scanning electron microscopy (FESEM), current voltage (I-V) measurements, ultraviolet-visual (UV-Vis) absorption spectroscopy and X-Ray diffraction.

Cadmium (Cd) is a potentially toxic trace element. Cereal grains contribute one-third to one-half of the Cd exposure via the diet. Among cereal grains, wheat generally contains the highest Cd concentration and the bran and germ fractions contain more Cd than the endosperm. An increase in the consumption of unrefined grains may cause an increase in the body burden of Cd if an increase in the exposure to Cd via the diet leads directly to increased Cd absorption and accumulation. However, there is evidence that certain factors may reduce the availability of Cd for absorption from the diet. The purposes of these studies were to refine an atomic absorption spectrometric method for measuring the accumulation of Cd from diets with low, naturally occuring concentrations of Cd, to evaluate the extent to which Cd is accumulated from different milling fractions of wheat and from different cereal grains, and to determine to what extent the presence of certain minerals and mineral-binding factors in the diet and the iron (Fe) status of the individual affect Cd accumulation from cereal grain diets. The results of the method studies showed that the amount of Cd in the liver and kidneys of rats after six weeks on different diets and the retention of 109Cd in these organs three weeks after the ingestion of 109Cd-labelled test meals of the diets were in agreement on the fractional and total accumulation of Cd from the diets. To a first approximation, the accumulation of Cd in the liver and kidneys in rats appears to be the product of the separate effects of the concentration of Cd in the diet which is available for absorption and the Fe status of the rats. The Cd concentration in grains varied by a factor of five between whole wheat and rye and the amounts of Cd accumulated in rats from diets with whole grains were nearly proportional to the Cd concentrations in the grains. The fractional accumulation of Cd was lower in rats given diets with whole grains or wheat fractions high in fiber and phytic acid than in rats fed endosperm wheat diets. This lower fractional Cd accumulation did not compensate for the high Cd concentrations in whole wheat and wheat bran. The fractional accumulation of Cd in the liver of rats is inversely related to their Fe status. The fractional Cd accumulation in the liver of rats with low Fe status was as much as ten times that in rats with high Fe status. The Cd accumulation in the kidneys appears to be even more sensitive to Fe status. The accumulation of Cd in human placenta supports these conclusions. Women who eat diets with less cereal grain fiber and who also maintain their Fe stores during pregnancy generally accumulate less Cd in the placenta than those who eat more grain fiber and/or have lower Fe status. On the basis of these results, it is recommended that as much as possible of the dietary fiber from cereal grains should derive from grains with low Cd concentrations. It is also imperative that the diet provide sufficient Fe and other nutrients to promote Fe status and thereby limit Cd accumulation. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1993, härtill 5 uppsatser.</p> / digitalisering@umu

L'effet des contaminants environnementaux sur la grossesse, en particulier sur le développement du foetus, est l'un des sujets les plus « chauds » de la santé publique. Le potentiel des contaminants environnementaux (incluant les biphényles polychlorés (BPC), le plomb (Pb), le mercure (Hg), le cadmium (Cd) et le manganèse (Mn)) pour induire un retard de croissance du foetus à la suite d'une exposition in utero a été suggéré par plusieurs études épidémiologiques. Cependant, les effets des polluants émergents, tels que les retardateurs de flamme comme les polybromodiphényles éther (PBDE), sur la croissance foetale demeurent flous. Le poids à la naissance est influencé par une multitude de facteurs, y compris le tabagisme maternel, la masse corporelle de la mère, les complications de la grossesse ou la présence d’infections. La majorité des études épidémiologiques ne considère pas tous ces facteurs de risque de faible poids de naissance et analyse les contaminants de l'environnement, un par un. Objectifs : Déterminer la relation entre l'exposition environnementale aux PBDE, aux BPC et aux métaux (Pb, Hg, Cd, Mn) chez les femmes enceintes et le poids à la naissance, en considérant les facteurs de risques de petit poids de naissance confirmé par des évidences scientifiques. Méthodes : Cette étude est effectuée à l'aide de notre cohorte prospective de femmes enceintes, la cohorte GESTE, dans laquelle ont été recrutées 397 femmes enceintes à <20 semaines de grossesse, à leur première visite au Centre Hospitalier Universitaire de Sherbrooke (CHUS), Québec, Canada, entre 2007 et 2009. Lors de cette visite, le sang maternel a été recueilli pour l’analyse des PBDE, des BPC et des métaux. Les informations sociodémographiques ont été recueillies à l'aide de questionnaires lors d’entrevues avec les membres de l’équipe. Toutes les données sur la santé maternelle et les antécédents obstétricaux, les médicaments et l’accouchement ont été obtenues à partir des dossiers médicaux. Résultats : Les concentrations de métaux et de BPC chez les femmes enceintes dans notre étude étaient très faibles, alors que les concentrations de PBDE sont similaires à ceux répertorié dans les populations américaines, mais plus élevé qu'en Europe. Il n'y avait pas de corrélation significative entre la coexposition aux contaminants en début de grossesse et le poids de naissance après avoir pris en compte les facteurs de risque majeurs pour la restriction de croissance foetale. Conclusion Les résultats ne supportent pas l’idée de l'effet néfaste d'une exposition aux PBDE, aux BPC, au plomb, au mercure, au cadmium et au manganèse en début de grossesse sur le paramètre principal de la croissance foetale, le poids de naissance.

Phytoremediation, i.e., the use of plants to clean up contaminated soil, may serve as a feasible alternative if a high-biomass crop can be found that accumulates metals to a high.degree. Two plant species, corn (Zea mays) and Indian mustard (Brassica juncea), were grown in soil from a Superfund site contaminated with Pb and Cd (PbTota, = 65,200 mg/kg and CdTotI = 52 mglkg) over two croppings. Soil treatments consisted of composted sewage sludge (CSS), ethylenediaminetetraacetic acid (EDTA), and sodium citrate at two concentrations. In most cases, the EDTA and citrate treatments were superior in terms of extracting soil Pb into root tissue, and translocation of Pb into aboveground biomass. The CSS treatment typically resulted in the lowest Pb removal efficiencies. The high pH (7.4) and high exchange capacity of the CSS may have immobilized soil Pb. Soil Cd was generally more mobile than soil Pb. The EDTA2 treatment was most effective in removing soil Pb into roots, and translocation to shoots. Lead remaining in the soil after two croppings was mainly associated with the carbonate, organic, and residual fractions, which represent the less bioavailable form of this metal. / Department of Natural Resources and Environmental Management

There is an ever-increasing need to address problems associated with the creation and disposal of wastes which result from human activities. Pb and Cd contamination is a common problem at many abandoned and uncontrolled commercial and industrial sites. Phytoremediation is one technology that can be employed to remove metals such as Pb from the soil. This study investigated the effectiveness of several plant and soil treatments on the uptake and retention of Pb and Cd by vegetation from contaminated soil at a Superfund site. Field plots were established and plant treatments included a mixture of grasses including Festuca, Poa. and Phleum; red clover (Trifolium Pratense); and sunflower (Helianthus annuus). Soil treatments included a common NPK fertilizer, ethylenediaminetetraacetic acid (EDTA), dilute sulfuric acid (H2SO4), and a mixture of EDTA and H2SO4 (EDTA+H2SO4). Trifolium tissue contained a greater quantity of Pb (182 mg Pb/kg tissue) than that of Poa (65 mg Pb/kg tissue). Cadmium concentration was similar in Poa and Trifolium tissue. ranging from 7.2 to 10.6 mg/kg tissue. Different soil treatments affected Pb levels found in plant tissue in order of effectiveness: H2SO4>EDTA>NPK>EDTA+H2SO4 The effects of soil treatments on Cd levels were similar to those for Pb with a difference of 0.1 mg Cd/kg tissue between EDTA and NPK treatments. Soil amendments differentially influenced Pb bioavailability and uptake, with H2SO4 exhibiting the greatest positive influence on Pb and Cd concentration in tissue. There was no correlation between the quantity of Pb and Cd up taken by vegetation at the site. The current study demonstrated the capability of common native plant species to grow on toxic and infertile soils, and the ability to uptake Pb and Cd to a limited degree. Regardless of tissue concentrations of Pb or Cd, Poa coverage at the site was generally dense. demonstrating the ability of Poa to become established on toxic soils and prevent soil erosion. / Department of Natural Resources and Environmental Management

Pagrindinis šio tyrimo tikslas buvo įvertinti karčiojo kiečio vandeninio ekstrakto protekcinį poveikį kepenims, inkstams, širdžiai ir smegenims eksperimentiniame modelyje in vivo, veikiant kadmiu. Tyrimams atrinkta Švenčionių rajone surinkta karčiojo kiečio vaistinė augalinė žaliava, kurioje nustatyta mažiausia kadmio koncentracija (0,215±0,100 µg/g) lyginant su žaliavomis iš Vilkaviškio ir Ukmergės rajonų bei su augaline žaliava įsigyta vaistinėje. Siekiant įvertinti karčiojo kiečio protekcinį poveikį pasirinktas eksperimentinis modelis in vivo, kurį sudarė karčiojo kiečio vandeninio ekstrakto paruošimas, kontrolinės ir tiriamųjų grupių sudarymas, fiziologinių rodiklių vertinimas, organų mėginių paėmimas, mineralizavimas ir toksikologinė analizė. Tyrimui pasirinkti subrendę Wistar linijos žiurkių patinai. Kontrolinės grupės žiurkės 30 d. iš eilės buvo girdomos geriamuoju vandeniu ad libitum, Cd grupės žiurkės - kadmio chlorido vandeniniu tirpalu (2 mg/l) ad libitum, Cd+KKVE grupės žiurkės - kadmio chlorido vandeniniu tirpalu (2 mg/l) ad libitum ir karčiojo kiečio vandeniniu ekstraktu 200 mg/kg/d per os. Eutanazija atlikta 31 eksperimento dieną. Paimti kepenų, inkstų, širdies ir smegenų mėginiai mineralizuoti naudojant mineralizatorių „Multiwave 3000“. Kadmio koncentracijos nustatymas atliktas „Perkin-Elmer Zeeman 3030“ elektroterminiu atominiu absorbciniu spektrofotometru. Kadmio koncentracijos vidurkis kontrolinės grupės žiurkių kepenyse buvo 0,012±0,006 µg/g, Cd grupės –... [toliau žr. visą tekstą] / The main objective was to assess wormwood aqueous extract protective activity for rat liver, kidney, heart and brain in experimental model in vivo with orally administrated heavy metal cadmium. Wormwood plant material selected for this study was collected in Švenčioniai region. Plant material had the lowest average cadmium concentration (0.215±0.100 µg/g) compared with plant materials of Vilkaviškis and Ukmergė regions and plant material purchased from pharmacy. We established experimental animal model in vivo, with the aim to evaluate protective effects of wormwood. Experimental model consisted of wormwood aqueous extract preparation, control and experimental groups formation, physiological parameters evaluation, organ sampling, mineralization and toxicological analysis. Adult male Wistar rats were selected for the study. Control group rats were administrated with drinking water ad libitum, Cd group rats - with cadmium chloride aqueous solution (2 mg/l) ad libitum, Cd+KKVE group rats - with cadmium chloride aqueous solution (2 mg/l) ad libitum and wormwood aqueous extract 200 mg/kg/day orally for 30 consecutive days. After euthanasia on the 31st day of the experiment, liver, kidney, heart, and brain samples were mineralized using mineralizator Multiwave 3000. Cadmium concentrations were estimated with Perkin – Elmer Zeeman 3030 electrothermal atomic absorption spectrophotometer. Average cadmium concentration in control group rat liver was 0.012±0.006 µg/g, Cd group – 0.245±... [to full text]

This thesis presents the results of an investigation into the uptake and distribution of cadmium (Cd) in two cultivars of potato (Solanum tuberosum L.) shown to contain different concentrations of Cd in the tuber at maturity. An initial glasshouse trial sought to determine whether differences in tuber Cd between these two cultivars resulted from differences in uptake from the soil, or were due to differences in the allocation of Cd to the various tissues within the plant. Total uptake of Cd from the soil did not differ between cultivars, nor did the yield of tubers. However, there were marked differences in Cd distribution within the plant. Most of the differences in tuber Cd concentration could be accounted for by a large (3-fold) retention of Cd in the roots of cultivar Wilwash. The concentration of Cd in the shoots of Wilwash was also higher than of Kennebec, although to a lesser extent than the roots. Further studies were conducted to trace the pathways of Cd uptake and movement within the plant. A split-pot trial, involving long-term growth of potatoes in 109Cd-labelled soil, was undertaken to determine the overall pattern of Cd distribution and the importance of the root system in supplying Cd to the tubers. The root system of the potato plant is different to many plants, in that the main root system (basal roots) is augmented after tuber initiation by roots extending from the stolon and from the tuber itself. The basal roots were found to be the dominant source of Cd to all tissues and accounted for approximately 85 % of tuber Cd. The remaining tuber Cd was sourced directly from the stolon and tuber roots. However, there was no evidence of a direct link between the main (basal) root system and the stolons. Although Cd was found to accumulate in the periderm of the tubers, there was no uptake into the tuber tissue itself. Isotopic studies were undertaken to investigate the short-term movement of newly absorbed Cd in the xylem and the phloem. Cadmium was found to be highly mobile in both the xylem and phloem, with added Cd being rapidly assimilated into all tissues following both root and foliar application. Newly absorbed Cd was rapidly sequestered by the stems when applied to either the soil or to a source leaf, suggesting that the stems may act as a transitional storage pool when rapid turnover of nutrients and other mineral elements is required during tuber bulking. Inhibition of Cd uptake by zinc (Zn), has been proposed as a method for reducing the concentration of Cd in various agricultural crops, including potatoes. The ability of Zn to reduce Cd uptake was found to be highly dependent upon cultivar and on the concentration of Cd in the external medium. Although competition between Zn and Cd was found for cultivar Wilwash when the external concentration of Cd was low, when the concentration of Cd in the external media was high, increasing Zn served to increase Cd uptake. Both synergistic and competitive responses were also noted for cultivar Kennebec. However, the patterns of response were opposite to those evident in Wilwash. The complexity of these interactions highlighted the possible shortcomings in using soil applied Zn to limit Cd uptake by potatoes. / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2004.

This thesis presents the results of an investigation into the uptake and distribution of cadmium (Cd) in two cultivars of potato (Solanum tuberosum L.) shown to contain different concentrations of Cd in the tuber at maturity. An initial glasshouse trial sought to determine whether differences in tuber Cd between these two cultivars resulted from differences in uptake from the soil, or were due to differences in the allocation of Cd to the various tissues within the plant. Total uptake of Cd from the soil did not differ between cultivars, nor did the yield of tubers. However, there were marked differences in Cd distribution within the plant. Most of the differences in tuber Cd concentration could be accounted for by a large (3-fold) retention of Cd in the roots of cultivar Wilwash. The concentration of Cd in the shoots of Wilwash was also higher than of Kennebec, although to a lesser extent than the roots. Further studies were conducted to trace the pathways of Cd uptake and movement within the plant. A split-pot trial, involving long-term growth of potatoes in 109Cd-labelled soil, was undertaken to determine the overall pattern of Cd distribution and the importance of the root system in supplying Cd to the tubers. The root system of the potato plant is different to many plants, in that the main root system (basal roots) is augmented after tuber initiation by roots extending from the stolon and from the tuber itself. The basal roots were found to be the dominant source of Cd to all tissues and accounted for approximately 85 % of tuber Cd. The remaining tuber Cd was sourced directly from the stolon and tuber roots. However, there was no evidence of a direct link between the main (basal) root system and the stolons. Although Cd was found to accumulate in the periderm of the tubers, there was no uptake into the tuber tissue itself. Isotopic studies were undertaken to investigate the short-term movement of newly absorbed Cd in the xylem and the phloem. Cadmium was found to be highly mobile in both the xylem and phloem, with added Cd being rapidly assimilated into all tissues following both root and foliar application. Newly absorbed Cd was rapidly sequestered by the stems when applied to either the soil or to a source leaf, suggesting that the stems may act as a transitional storage pool when rapid turnover of nutrients and other mineral elements is required during tuber bulking. Inhibition of Cd uptake by zinc (Zn), has been proposed as a method for reducing the concentration of Cd in various agricultural crops, including potatoes. The ability of Zn to reduce Cd uptake was found to be highly dependent upon cultivar and on the concentration of Cd in the external medium. Although competition between Zn and Cd was found for cultivar Wilwash when the external concentration of Cd was low, when the concentration of Cd in the external media was high, increasing Zn served to increase Cd uptake. Both synergistic and competitive responses were also noted for cultivar Kennebec. However, the patterns of response were opposite to those evident in Wilwash. The complexity of these interactions highlighted the possible shortcomings in using soil applied Zn to limit Cd uptake by potatoes. / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2004.

[Truncated abstract] Infrared radiation detectors find application in a wide range of military and civilian applications: for example, target identification, astronomy, atmospheric sensing and medical imaging. The greatest sensitivity, response speed, and wavelength range is offered by infrared detectors based on HgCdTe semiconductor material, the growth and characterisation of which is the subject of this thesis. Molecular Beam Epitaxy (MBE) is a versatile method of depositing layers of semiconductor material on a suitable crystalline substrate. In particular, MBE facilitates the growth of multilayer structures, thus allowing bandgap engineered devices to be realised. By modulating the bandgap within the device structure it is possible to improve the sensitivity or increase the operating temperature of photodetectors when compared to devices fabricated on single layer material. Furthermore, dual-band detectors may be fabricated using multi-layered HgCdTe material. The bulk of this thesis is concerned with the development of the MBE process for multilayer growth, from modelling of the growth process to characterisation of the material produced, and measurement of photoconductive devices fabricated on these wafers. In this thesis a previously published model of HgCdTe growth by MBE is reviewed in detail, and is applied to the growth of double layer heterostructures in order to determine the optimum method of changing the mole fraction between layers. The model has been used to predict the change in the temperature of the phase limit when the mole fraction and growth rate change suddenly as is the case during growth of an abrupt heterostructure. Two options for growth of an abrupt heterostructure were examined (a) modulating the CdTe flux and (b) modulating the Te flux. The change in the phase limit temperature between the layers was calculated as being 4:1±C for option (a) and 5:2±C for option (b) when growing a Hg(0:7)Cd(0:3)Te/Hg(0:56)Cd(0:44)Te heterostructure

Thèse (D. en biochimie)--Université du Québec à Montréal, 2005. / En tête du titre: Université du Québec à Montréal. Comprend des réf. bibliogr. Publié aussi en version électronique.