Siga este link para ver outros tipos de publicações sobre o tema: Effect of zinc on.
Teses / dissertações sobre o tema "Effect of zinc on"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Effect of zinc on".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
1
Nedic, Stanko. "Zinc oxide nanowire field effect transistors". Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708233.
Texto completo da fonte
2
Thomas, Louise. "The effect of zinc deprivation on protein energy and zinc metabolism in man". Thesis, University of Aberdeen, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245359.
Texto completo da fonteResumo:
Dietary zinc deficiency was induced in four healthy male volunteers. The diet used was high in phytate (phytate:zinc molar ratio 381) and the depletion period was preceded by a 3 day starvation period. In the depletion period, there was a significant decrease in plasma zinc and urinary zinc excretion. The subjects also adapted to the low zinc intake by decreasing the faecal excretion of zinc. One subject (No.2) developed clinical signs of zinc deficiency and also had the lowest plasma zinc concentration at the end of the depletion stage. Whole body protein turnover was assessed by an 8hr primed constant infusion of Li-[1-13C]leucine. Zinc deficiency had an effect on whole body protein turnover in only one subject (No. 2). In this subject, there was a decrease in leucine oxidation (71%), protein synthesis (31%) and degradation (39%). In this group as a whole, zinc depletion was associated with a significant decrease in urinary excretion of 3-methylhistidine. Zinc deficiency appeared to have no effect on substrate utilization. With regard to zinc kinetics, zinc deficiency was associated with a significant decrease in the size of the plasma zinc pool and a liver pool. There was also a decrease in the flux between these two zinc pools, and an increase in the fractional decay of zinc from the plasma pool to the liver pool. Two further studies were carried out. In 4 volunteers the effect of a 3 day starvation period on whole body protein turnover and zinc kinetics was investigated. There was a significant increase in leucine oxidation and in the size of a liver zinc pool. In 6 volunteers, the effect of phytate on zinc kinetics was investigated. The addition of phytate to the test meal, (phytate:zinc molar ratio 88) was associated with a decrease in the size of a liver zinc pool.
3
Neilsen, Denise. "Characterization and plant availability of zinc in British Columbia orchard soils". Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72835.
Texto completo da fonte
4
Turner, Gary Chandler. "Zinc Oxide MESFET Transistors". Thesis, University of Canterbury. Electrical and Computer Engineering, 2009. http://hdl.handle.net/10092/3439.
Texto completo da fonteResumo:
Zinc oxide is a familiar ingredient in common household items including sunscreen and medicines. It
is, however, also a semiconductor material. As such, it is possible to use zinc oxide (ZnO) to make
semiconductor devices such as diodes and transistors. Being transparent to visible light in its
crystalline form means that it has the potential to be the starting material for so-called 'transparent
electronics', where the entire device is transparent. Transparent transistors have the potential to
improve the performance of the electronics currently used in LCD display screens.
Most common semiconductor devices require the material to be selectively doped with specific
impurities that can make the material into one of two electronically distinct types – p- or n-type.
Unfortunately, making reliable p-type ZnO has been elusive to date, despite considerable efforts
worldwide. This lack of p-type material has hindered development of transistors based on this
material.
One alternative is a Schottky junction, which can be used as the active element in a type of transistor
known as a metal-semiconductor field effect transistor, MESFET. Schottky junctions are traditionally
made from noble metal layers deposited onto semiconductors. Recent work at the Canterbury
University has shown that partially oxidised metals may in fact be a better choice, at least to zinc
oxide.
This thesis describes the development of a fabrication process for metal-semiconductor field effect
transistors using a silver oxide gate on epitaxially grown zinc oxide single crystals. Devices were
successfully produced and electrically characterised. The measurements show that the technology has
significant potential.
5
Lopes, Sílvia Ferreira. "Effect of zinc oxide nanoparticles in Daphnia magna". Master's thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/10258.
Texto completo da fonteResumo:
Mestrado em Biologia Aplicada - Toxicologia e EcotoxicologiaO rápido desenvolvimento da nanotecnologia com o consequente aumento na produção de nanopartículas e nanoprodutos oferece muitas oportunidades mas também muitos desafios. A nanotecnologia tem vindo a ser descrita como uma área multidisciplinar que visa desenvolver uma variedade de nanoparticulas para aplicações medicinais e industriais. As propriedades que trazem às nanoparticulas especial atenção – pequeno tamanho, elevada área de superfície e consequente elevado grau de reatividade – podem também torná-las potencialmente perigosas para a saúde humana e para o ecossistema. A avaliação dos potenciais riscos inerentes à exposição das nanoparticulas torna-se portanto uma investigação de prioridade antes que estas sejam aplicadas em produtos comerciais e libertadas para o ambiente. Os ambientes aquáticos (de água doce e marinho) são considerados como potenciais destinos das nanoparticulas libertadas para o ambiente através de fontes diretas e/ou indiretas, expondo assim os organismos aquáticos a elevados níveis de contaminação. As nanoparticulas de óxido de zinco (ZnO-NPs) são uma das nanoparticulas mais utilizadas numa vasta gama de produtos comerciais (ex: protetores solares, cosméticos e tintas) e a sua produção estima-se que irá continuar a aumentar nos próximos anos. Em consequência, o risco de contaminação aquática por parte destas nanoparticulas irá forçosamente aumentar. Estudos toxicológicos já demonstraram que as ZnO-NPs exercem efeitos tóxicos em vários organismos, como por exemplo, em crustáceos, algas e bactérias. Os efeitos tóxicos das nanoparticulas são complexos e podem estar dependentes de vários fatores, tais como, o organismo-teste, fatores abióticos (pH, salinidade, dureza da água e presença de matéria orgânica), propriedades físico-quimicas das nanoparticulas, processos de adsorção, presença de outros contaminantes, entre outros. Os objetivos principais deste trabalho consistiram em avaliar a toxicidade das ZnO-NPs com diferentes tamanhos (30 e 80-100 nm) no cladócero Daphnia magna e comparar estes efeitos com os homólogos de tamanho micrómetro (ZnO > 200 nm) e a forma iónica (ZnCl2). Os efeitos foram avaliados nos parâmetros de imobilização, inibição alimentar e reprodução. Os resultados mostraram uma relação dose-resposta entre o decréscimo dos parâmetros avaliados e a concentração das ZnONPs, ZnO de tamanho micrómetro e ZnCl2 testadas. De acordo com os resultados obtidos foi possível concluir que o ZnCl2 induziu maior toxicidade aguda para a D. magna. Contudo, para a reprodução e inibição alimentar, as nanoparticulas de ZnO mostraram ter um efeito mais tóxico. Foi observado igualmente que o tamanho das nanopartículas não influenciou a toxicidade do ZnO. Este estudo realça a importância de se estudarem os efeitos de nanoparticulas de diferentes tamanhos uma vez que este é um parâmetro-chave que deve ser considerado quando se pretende estudar a toxicidade de nanoparticulas para o ambiente.
The rapid development of nanotechnology with the consequent increase in the production of nanoparticles and nanoproducts presents many opportunities but also many challenges. Nanotechnology has been described as a multidisciplinary field that develops a variety of engineered nanoparticles (ENPs) for medical and industrial applications. The properties that bring to ENPs special attention for commercial products – small size, large surface area and consequently high degree of reactivity – can also make them potentially harmful for human and ecosystem health. Therefore, assessing the potential risks associated with exposure of ENPs should be considered a major research priority before they are applied in commercial products and released to the environment. Aquatic (freshwater and marine) environment act as potential destinations for the ENPs released to the environment through direct and/or indirect sources, thus exposing aquatic organisms to high levels of pollutants. Zinc oxide nanoparticles (ZnO-NPs) are one of the ENPs most applied in a wide range of commercial products (e.g., sunscreens, cosmetics and paints) and its production is estimated to continue to rise in the upcoming years. As a consequence, the risk of aquatic environment contamination by these ENPs will increase. Toxicological studies have already demonstrated that nanoscale ZnO exert toxic effects in several organisms, such as crustaceans, algae and bacteria. The toxic effects of ZnO-NPs can be complex and may be dependent of several factors such as organism tested, abiotic factors (pH, salinity, water hardness, presence of natural organic matter), physico-chemical properties of NPs, adsorption phenomena, presence of other pollutants in the same environment, among others.
6
Khan, Habib Ur Rahman. "Responses of chickpea (Cicer arietinum L.) to zinc supply and water deficits". Title page, contents and summary only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phk4446.pdf.
Texto completo da fonteResumo:
Bibliography: leaves 201-228. Widespread deficiencies of mineral nutrients in soils along with limited moisture supply are considered major environmental stresses leading to yield losses in chickpea. This study was conducted to determine the zinc requirement of chickpea and the effect on plant water relations. Critical zinc concentration was estimated. It was found that high and low moisture regimes had no effect on critical zinc concentration and that the value remained almost the same in all chickpea genotypes. Sensitivity of 28 chickpea genotypes were evaluated at two zinc levels. Field studies on zinc fertilization in both Australia and Pakistan showed that the application of zinc increased grain yield in all chickpea genotypes. It was found that plants grown under zinc deficiency could not exploit available soil moisture and water use and water use efficiency was reduced, and concluded that high zinc availability may enhance the ability of plants to endure periods of drought by promoting osmotic adjustment.
7
Steel, Helen Carolyn. "Metabolic responses to in vitro zinc supplementation". Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1004101.
Texto completo da fonteResumo:
The present study was carried out to determine the effects and possible mechanism of action of zinc supplementation on the in vitro growth of malignant murine melanoma (B16) and non-malignant monkey kidney (LLCMK) cells. Cell culture studies showed that zinc supplementation significantly inhibited B16 growth at all the concentrations studied (1, 3, 5 and lOμg/ml). Zinc was also found to inhibit the growth of the LLCMK cells, although to a lesser extent than the B16 cells. Possible evidence of mobilisation of the essential fatty acids from the membrane phospholipid stores was noted in both cell types. This effect was, however, greater in the B16 cells. Δ⁶-desaturase activity was found to be significantly lower in the B16 cells than in the LLCMK cells (p ≥ 0.05). Zinc supplementation resulted in an increase in the enzymes activity in the LLCMK cells and, at high concentrations, in the B16 cells. An estimation of elongase and Δ⁶-desaturase activity with zinc supplementation indicated that zinc had little or no effect on the activity of these enzymes. B16 cells were found to have higher levels of free radicals than the LLCMK cells. Zinc supplementation resulted in increased free radical formation in the B16 cells, while no effect was observed in the LLCMK cells. Lipid peroxidation increased in both cell types with increased zinc concentrations. The observed effect of zinc supplementation on cell growth may involve these elevated levels of lipid peroxides. CycIo-oxygenase activity was found to be greater in the B16 cells than the LLCMK cells. The activity of the enzyme increased with higher concentrations of zinc (lOμg/ml) in both cell types. Prostaglandin E, levels were found to be lower in the B16 cells compared to the LLCMK cells. The levels of prostaglandin E, in both cell types appeared to be dependent on the levels of the polyunsaturated fatty acid precursors to the prostaglandins. Zinc was found to inhibit the activity of the enzyme adenylate cyclase in both cell types. The cAMP levels in the LLCMK cells were also found to decrease with zinc supplementation. In the case of the B16 cells, cAMP levels increased at low concentrations of zinc despite a decrease in adenyl ate cyclase activity, suggesting a possible inhibition of cAMP phosphodiesterase activity at these concentrations of zinc. It is concluded that although zinc supplementation does have an effect on cell growth, this effect is not mediated through the activation of adenylate cyclase by the prostaglandins resulting in elevated levels of cAMP. A possible mechanism involving lipid peroxidation is proposed.
8
Kalinowski, Juan. "Effect of low dietary zinc supply during pregnancy and lactation on the sow and the neonatal piglet". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72019.
Texto completo da fonteResumo:
Experiments were conducted with sows and littermate-gilts to investigate the effect of dietary zinc (Zn) restriction during either part or most of the pregnancy and lactation on dams and their offspring.Reduced dietary Zn (13 ppm) during the last 4 wk of pregnancy and first 2 wk of lactation presented no serious consequences to the dam or offspring. Reduction of dietary Zn throughout pregnancy and lactation (10 ppm) caused overt signs of Zn deficiency in one-half of the gilts, however, their offspring exhibited no obvious abnormalities. Zinc restriction did not affect feed consumption but depressed plasma and urinary Zn and plasma alkaline phosphatase activity (APA). The use of the balance technique and radiotracers revealed that gilts deficient in Zn initiated protective mechanisms such as, increased Zn absorption reduced endogenous Zn excretion, prolongation of the biological half life of Zn; all these responses affected higher efficiency of Zn utilization.
Despite the protective mechanisms, gilts depleted in Zn exhibited prolonged stressful parturition and a high incidence of intrapartum and neonatal mortality than control gilts. Piglets from gilts depleted in Zn showed depressed birth weight, reduced concentrations of plasma Zn, Cu and ammonia and low APA and hematocrit, increased plasma concentrations of glucose and lactate, reduced content of Zn in liver, heart, lung, skin, bone and carcass and higher concentrations of Cu and Mn in various tissues compared to controls. Zinc depletion did not change the Zn content of colostrum but did change it in milk. Content of Cu, Fe, and Mn was effected in colostrum and milk. Weight of piglets was lower at one wk but not at two wk of age. Two-week old piglets exhibited lower Zn and higher Cu concentrations in plasma; reduced Zn and increased Cu and Mn concentrations in liver and bone and changes in Cu and Mn in other tissues. At the end of lactation, gilts depleted in Zn exhibited low level of Zn and APA in plasma; reduced Zn content in liver, spleen, heart, small intestine; increased Cu content in liver and small intestine; increased Zn and Mn content in brain.
Although gilts depleted in Zn exhibited a highly efficient handling of Zn via homeostatic mechanisms, the reduced amount of corporal exchangeable Zn in these gilts caused biochemical changes affecting the performance of the dam and the offspring. (Abstract shortened with permission of author.)
9
Brocavich-Nielsen, Juliann M. "Effect of dietary zinc and copper on plasma zinc, copper, total cholesterol in young adult males". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040757/.
Texto completo da fonte
10
Tiwale, Nikhil. "Zinc oxide nanowire field effect transistors for sensor applications". Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/268227.
Texto completo da fonteResumo:
A wide variety of tunable physio-chemical properties make ZnO nanowires a promising candidate for functional device applications. Although bottom-up grown nanowires are producible in volume, their high-throughput device integration requires control over dimensions and, more importantly, of precise placement. Thus development of top-down fabrication routes with accurate device positioning is imperative and hence pursued in this thesis. ZnO thin film transistors (TFT) were fabricated using solution based precursor zinc neodecanoate. A range of ZnO thin films were prepared by varying process parameters, such as precursor concentrations and annealing temperatures, and then analysed for their optical and electrical characteristics. ZnO TFTs prepared from a 15 % precursor concentration and annealing at 700 $^\circ$C exhibited best device performance with a saturation mobility of 0.1 cm$^2$/V.s and an on/off ratio of 10$^7$. Trap limited conduction (TLC) transport was found to be dominant in these devices. A direct-write electron beam lithography (EBL) process was developed using zinc naphthenate and zinc neodecanoate precursors for the top-down synthesis of ZnO nanowires. Nanoscale ZnO patterns with a resolution of 50 nm and lengths up to 25 $\mu$m were fabricated. A linear mobility of 0.5 cm$^2$/V.s and an on/off ratio of $\sim$10$^5$ was achieved in the micro-FETs with 50 $\mu$m channel width. Interestingly, on scaling down the ZnO channel width down to 100 nm, almost two orders of magnitude enhancement in the linear mobility was observed, which reached $\sim$33.75 cm$^2$/V.s. Such increment in the device performance was attributed to the formation of larger grains and thus reduction in the grain-boundary scattering. Six volatile organic compounds (VOCs) were sensed at room temperature using the direct-write EBL fabricated ZnO devices under UV sensitisation. As the surface-to-volume ratio increases with the decreasing channel width (from 50 $\mu$m to 100 nm), sensing response of the ZnO devices becomes more significant. Ppm level detection of various VOCs was observed; with a 25 ppm level Anisole detection being the lowest concentration. Additionally, using 100 nm device, detection of 10 ppm NO$_2$ was achieved at room temperature. The sensing response towards NO$_2$ was found to be increased with UV illumination and sensor temperature. This led to exhibit $\sim$171 % sensing response for a 2.5 ppm level of NO$_2$.
11
Tabbaa, Mahmmoud M. "Pyrithione Zinc effect on Cancer Cell Proliferation and Viability". Ohio University Art and Sciences Honors Theses / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1509614945218889.
Texto completo da fonte
12
Tani, Fahima. "Zinc and copper uptake by wheat and buckwheat under two transpiration rates". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79142.
Texto completo da fonteResumo:
Wastewater has become a vital new supply for irrigation; however, concerns are mounting about environmental and health hazards related to heavy metals present in wastewater. Experiments were conducted to evaluate wheat ( Triticum aestivum L.) and buckwheat (Fagopyrum esculentum L.) uptake of copper (Cu) and zinc (Zn).Some 15 plants per pot were allowed to establish themselves in the greenhouse for 4 and 6 weeks for buckwheat and wheat, respectively. Plants were then transferred to one of two growth chambers differing in the vapor pressure deficit (VPD), creating conditions for two different transpiration rates to occur: high (HT) and low (LT). A total 48 pots for each crop were seeded in order to evaluate the effect of 8 treatment combinations of Cu and Zn (0/0, 5/0, 15/0, 30/0, 0/25, 5/25, 15/25, 30/25) levels (mg L-1). Treatments were laid out in a completely randomized design within each growth chamber.
Three plants were harvested from each pot at days 10 and 20 for wheat, and days 6, 12 and 18 days for buckwheat to measure dry mass and Cu and Zn content in different plant parts. Heavy metal treatments had no significant effect on transpiration rate for either crops. The higher transpiration rate increased Cu/Zn uptake. A Zn amendment in the absence of Cu had a beneficial effect on buckwheat growth, whereas with Cu at 15 mg Cu L-1 or 30 mg Cu L-1 the lowest dry weights were recorded, regardless of the transpiration rate. Roots contained greater concentrations of Cu and Zn, irrespective of the treatment level and transpiration rate, than did stems, leaves or grain. High retention of heavy metals in the roots of cereal crops may be desirable because these parts are not generally utilized as food or feed.
13
Kim, ChulHwan. "The effect of dietary zinc level upon the efficiency of vitellogenin synthesis by male quail". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040742/.
Texto completo da fonte
14
Cha, Ming Chuan 1955. "The effect of zinc deficiency on the growth promoting actions of growth hormone and insulin-like growth factor-I /". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55484.
Texto completo da fonteResumo:
The effect of zinc deficiency on the growth promoting effect of circulating IGF-I and the direct growth effect of GH on long bone growth were investigated. Food intake was decreased by lack of zinc in the diet. Tissue zinc content and plasma alkaline phosphatase activity were reduced by zinc deficiency. Systemic administration of human IGF-I increased the body weight, tail length and tibia epiphyseal cartilage width of control animals. This somatogenic action was impaired by zinc deficiency, as evidenced by continued weight loss, no increase in tail length and decreased tibial epiphyseal cartilage width of zinc deficient animals. Unilateral arterial infusion of GH increased the tibial epiphyseal width of the treated limb but not of the non-treated limb in control rats. However, no difference was found between the infused and the non-infused limb of zinc deficient animals, suggesting the occurrence of GH resistance on long bone growth in zinc deficiency. We conclude that zinc deficiency inhibits the growth promoting action of circulating IGF-I and the direct growth effect of GH on long bone growth.
15
zhang, peilun. "Zn Corrosion in Alkaline Aqueous Electrolytes: Effect of Electrolyte Composition on Corrosion Rate and Inhibitors to Suppress Corrosion". Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1618400150411797.
Texto completo da fonte
16
Mulyati. "Zinc requirements of transplanted oilseed rape". Thesis, Mulyati, (2004) Zinc requirements of transplanted oilseed rape. PhD thesis, Murdoch University, 2004. https://researchrepository.murdoch.edu.au/id/eprint/213/.
Texto completo da fonteResumo:
Transplanting is a common practice for many horticultural crops and some field crops. Recently, transplanted oilseed rape (Brassica napus L.) crops have been reported to be sensitive to zinc (Zn) deficiency. However, Zn nutrition in transplanted field crops has not been investigated in detail. The objectives of this present research were to investigate whether transplanting increases external Zn requirements of transplanted oilseed rape, and the mechanisms of root function, growth and Zn uptake after transplanting including rhizosphere modification capacity by plant roots. The second objective was to examine the relative effects of root pruning and transplanting on Zn responses of oilseed rape, and the third objective was to determine external and internal Zn requirements of transplanted oilseed rape for diagnosing and predicting Zn deficiency.
An experiment on a low Zn sand (DTPA extractable Zn 0.14 mg kg-1) was set up to determine whether transplanted oilseed rape had a higher Zn requirement than that of direct-sown plants. Low Zn supply depressed shoot dry weight, however, root growth was relatively more strongly suppressed than shoots. Maximum root dry weight required much higher external Zn for transplanted plants compared to direct-sown plants, whilst shoot dry weight required a similarly low external Zn supply. In addition, transplanted plants were sensitive to zinc deficiency during the early post-transplanting growth, and the response weakened as the plants recovered from root injury or transplanting stress. However, the transplanted plants also experienced root pruning before transplanting and so in this experiment the higher Zn requirement could have been due to root pruning or transplanting or both.
A further experiment was undertaken to determine the comparative external Zn requirements of direct-sown and transplanted plants in well-stirred chelate-buffered solution culture where a rhizosphere effect on plant availability of Zn forms is absent and the effects of poor root-soil contact on post-transplanting growth are minimized. In solution culture at the same level of Zn supplied, direct- sown plants produced higher shoot and root dry matter and greater root length than those of transplanted plants. However, since a higher external Zn requirement was found for transplanted plants in buffered solution culture than for direct- sown plants, it was concluded that the higher Zn requirement was not related to decreased rhizosphere modification, to greater demand for Zn or to poor root-solution contact, but rather to the time required for transplanted plants to recover from transplanting and root injury. The recovery of root function in solution culture was more rapid than that in soil culture and expressed as a higher Zn requirement for shoot as well as root growth. It suggested that the delay in root recovery in soil culture was due to slower absorption of Zn from the soil after transplanting than was the case in solution culture.
Chelate-buffered nutrient solution culture and harvesting plants successively at 5 day intervals until 25 days after transplanting was used to examine the mechanisms of the recovery of root growth and function. In this experiment, the external Zn requirement of transplanted plants was investigated with unpruned or pruned root systems. Plants with unpruned root system and sufficient Zn supply exhibited faster recovery from transplanting than those with pruned root system plants. The results suggest that root pruning impaired Zn uptake by plant roots and slowed down the root and shoot growth after transplanting. Increased solution Zn partly alleviated the effects of root pruning and presumably this is a major reason why transplanted oilseed rape had a high external Zn requirement. However, root pruning also appeared to impair water uptake, and may have suppressed shoot growth through sequestering carbon for new root growth and through decreased phytohormone production by roots.
Since rapid root recovery of transplanted plants is essential for successful of growth in the field, Zn application to the nursery bed was explored as a starter fertilizer to stimulate root growth after transplanting. The objective of this experiment was to determine whether increasing the seedbed Zn would stimulate new root growth of transplanted oilseed rape, and therefore would alleviate the need for increased external Zn for post-transplanting growth. Results showed that adequate Zn concentration in the seedbed promoted the post-transplanting growth by stimulating the new root growth especially increased root length, and also hastened the recovery of root systems. However, high Zn concentration at transplanting still had a more dominant effect in stimulating the new root growth of oilseed rape after transplanting.
The final experiment was set up using rhizobags with three rates of Zn supply and unpruned or pruned root systems. The purpose of this study was to investigate the chemical change in the rhizosphere and non-rhizosphere or bulk soil and its relationship to the recovery of root function after transplanting, and also to identify and quantify the organic acids in soil extracts of direct-sown and transplanted plants. The rhizosphere soil pH was lower than that of non-rhizosphere soil, and the decrease of soil pH was suggested as the mechanism of the increase of Zn availability and mobility in the rhizosphere soil. Direct-sown plants were more efficient in utilizing Zn than those of transplanted plants especially compared to those of plants with pruned root system. Zinc deficient plants excreted higher concentration of organic acids particularly citric acid, suggesting this was a mechanism of Zn mobilization and Zn uptake by roots of oilseed rape.
The main implications of the present study for the management of Zn nutrition of transplanted crops were: the need to increase the Zn application to crops in the nursery and at transplanting compared to direct-sown plants; the possibility that external requirements of other nutrients will be greater in transplanted crops also requires further consideration; and in cropping systems where transplanting is practised, greater attention should be given to the avoidance of root damage during the transplanting.
17
Mulyati. "Zinc requirements of transplanted oilseed rape". Murdoch University, 2004. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060109.135933.
Texto completo da fonteResumo:
Transplanting is a common practice for many horticultural crops and some field crops. Recently, transplanted oilseed rape (Brassica napus L.) crops have been reported to be sensitive to zinc (Zn) deficiency. However, Zn nutrition in transplanted field crops has not been investigated in detail. The objectives of this present research were to investigate whether transplanting increases external Zn requirements of transplanted oilseed rape, and the mechanisms of root function, growth and Zn uptake after transplanting including rhizosphere modification capacity by plant roots. The second objective was to examine the relative effects of root pruning and transplanting on Zn responses of oilseed rape, and the third objective was to determine external and internal Zn requirements of transplanted oilseed rape for diagnosing and predicting Zn deficiency.
An experiment on a low Zn sand (DTPA extractable Zn 0.14 mg kg-1) was set up to determine whether transplanted oilseed rape had a higher Zn requirement than that of direct-sown plants. Low Zn supply depressed shoot dry weight, however, root growth was relatively more strongly suppressed than shoots. Maximum root dry weight required much higher external Zn for transplanted plants compared to direct-sown plants, whilst shoot dry weight required a similarly low external Zn supply. In addition, transplanted plants were sensitive to zinc deficiency during the early post-transplanting growth, and the response weakened as the plants recovered from root injury or transplanting stress. However, the transplanted plants also experienced root pruning before transplanting and so in this experiment the higher Zn requirement could have been due to root pruning or transplanting or both.
A further experiment was undertaken to determine the comparative external Zn requirements of direct-sown and transplanted plants in well-stirred chelate-buffered solution culture where a rhizosphere effect on plant availability of Zn forms is absent and the effects of poor root-soil contact on post-transplanting growth are minimized. In solution culture at the same level of Zn supplied, direct- sown plants produced higher shoot and root dry matter and greater root length than those of transplanted plants. However, since a higher external Zn requirement was found for transplanted plants in buffered solution culture than for direct- sown plants, it was concluded that the higher Zn requirement was not related to decreased rhizosphere modification, to greater demand for Zn or to poor root-solution contact, but rather to the time required for transplanted plants to recover from transplanting and root injury. The recovery of root function in solution culture was more rapid than that in soil culture and expressed as a higher Zn requirement for shoot as well as root growth. It suggested that the delay in root recovery in soil culture was due to slower absorption of Zn from the soil after transplanting than was the case in solution culture.
Chelate-buffered nutrient solution culture and harvesting plants successively at 5 day intervals until 25 days after transplanting was used to examine the mechanisms of the recovery of root growth and function. In this experiment, the external Zn requirement of transplanted plants was investigated with unpruned or pruned root systems. Plants with unpruned root system and sufficient Zn supply exhibited faster recovery from transplanting than those with pruned root system plants. The results suggest that root pruning impaired Zn uptake by plant roots and slowed down the root and shoot growth after transplanting. Increased solution Zn partly alleviated the effects of root pruning and presumably this is a major reason why transplanted oilseed rape had a high external Zn requirement. However, root pruning also appeared to impair water uptake, and may have suppressed shoot growth through sequestering carbon for new root growth and through decreased phytohormone production by roots.
Since rapid root recovery of transplanted plants is essential for successful of growth in the field, Zn application to the nursery bed was explored as a starter fertilizer to stimulate root growth after transplanting. The objective of this experiment was to determine whether increasing the seedbed Zn would stimulate new root growth of transplanted oilseed rape, and therefore would alleviate the need for increased external Zn for post-transplanting growth. Results showed that adequate Zn concentration in the seedbed promoted the post-transplanting growth by stimulating the new root growth especially increased root length, and also hastened the recovery of root systems. However, high Zn concentration at transplanting still had a more dominant effect in stimulating the new root growth of oilseed rape after transplanting.
The final experiment was set up using rhizobags with three rates of Zn supply and unpruned or pruned root systems. The purpose of this study was to investigate the chemical change in the rhizosphere and non-rhizosphere or bulk soil and its relationship to the recovery of root function after transplanting, and also to identify and quantify the organic acids in soil extracts of direct-sown and transplanted plants. The rhizosphere soil pH was lower than that of non-rhizosphere soil, and the decrease of soil pH was suggested as the mechanism of the increase of Zn availability and mobility in the rhizosphere soil. Direct-sown plants were more efficient in utilizing Zn than those of transplanted plants especially compared to those of plants with pruned root system. Zinc deficient plants excreted higher concentration of organic acids particularly citric acid, suggesting this was a mechanism of Zn mobilization and Zn uptake by roots of oilseed rape.
The main implications of the present study for the management of Zn nutrition of transplanted crops were: the need to increase the Zn application to crops in the nursery and at transplanting compared to direct-sown plants; the possibility that external requirements of other nutrients will be greater in transplanted crops also requires further consideration; and in cropping systems where transplanting is practised, greater attention should be given to the avoidance of root damage during the transplanting.
18
Simon, Kathryn D. "Effect of cellular zinc concentration on glucocorticoid induced gene expression". Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-155344/.
Texto completo da fonte
19
Odendaal, James Philander. "Histological change in the hepatopancreas of terrestrial isopods as potential biomarker of cadmium and zinc exposure". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52877.
Texto completo da fonteResumo:
Thesis (PhD)--Stellenbosch University, 2002.ENGLISH ABSTRACT: Metals occur naturally in the environment but since the industrial revolution the amounts ofbioavailable metals in the environment have increased significantly. There are various anthropogenic sources of metals in the environment. In recent years there has been an increasing interest in the use of biomarkers in terrestrial invertebrates for the assessment of the potential adverse effects of chemicals in soil ecosystems. Terrestrial isopods are one of the groups that play an important role in the decomposition process as fragmentors of dead plant material in soil ecosystems. They are also known to accumulate contaminants in their bodies, especially in the hepatopancreas. Cadmium has no known biological function and is deposited in the environment through a variety of sources. Zinc on the other hand is one of the essential metals and play an important role in the normal metabolism of animals. Zinc too, is deposited in the environment through a variety of anthropogenic sources. The aim of this study was to undertake an experimental and field evaluation of the role cellular change in the hepatopancreas of terrestrial isopods can play in conjunction with other sublethal responses to contribute to the assessment of the impact of cadmium and zinc in terrestrial ecosystems. Porcel/io laevis was used as test species in the laboratory experiments in this study, to conduct sublethal toxicity tests. Cadmium- and zinc sulphate were used as the contaminants, applied separately and as mixtures. The isopods were weighed before the beginning of the exposures and every week throughout the exposure period of six weeks. At the end of the exposure period they were dissected to remove the hepatopancreas. The zinc and cadmium content of the hepatopancreases and rest of the bodies of the isopods were determined by atomic absorption spectrophotometry. Hepatopancreas samples were also prepared for histological analysis, and measurements of the Percentage Cellular Area (PCA) were made using image analysis. Specimens of Porcellionides pruinosus were collected from contaminated- and uncontaminated field sites. Hepatopancreas- and rest of the body samples of P. pruinosus were also analysed for cadmium and zinc. Histological sections of the hepatopancreas were similarly prepared and analysed, as in the laboratory experiments. Exposure to cadmium- and zinc sulphate affected the mass of P. laevis negatively in the single metal exposures. However, these two metals "neutralised" each other's effects in the mixture toxicity exposures, pointing towards an antagonistic interaction. Administered cadmium- and zinc sulphate resulted in the accumulation of cadmium and zinc in the isopods, especially in the hepatopancreas. In the mixture toxicity experiments cadmium and zinc influenced the accumulation of each other. Cadmium- and zinc sulphate, whether administered separately or as mixtures, changed the structure of the hepatopancreas and this was quantitatively shown through PCA measurements. PCA of the hepatopancreas of terrestrial isopods was shown to be a good general biomarker of exposure and effects for cadmium as well as for zinc. It is suggested that PCA could serve as a general biomarker to predict possible impairment of growth or mass change of isopods exposed to cadmium and zinc mixtures. The findings of the field survey also suggest that PCA may be suitable to be used as a general biomarker to measure metal induced stress in woodlice from contaminated field sites.
AFRIKAANSE OPSOMMING: Metale kom natuurlik voor in die omgewing, maar sedert die industriële revolusie het die hoeveelheid bio-beskikbare metale in die omgewing betekenisvol toegeneem. Daar is verskeie antropogeniese bronne van metale in die omgewing. Die afgelope paar jaar was daar toenemende belangstelling in die gebruik van biomerkers by terrestriële invertebrate vir die assessering van potensiële negatiewe effekte van chemiese stowwe in grondekosisteme. Terrestriële Isopoda is een van die groepe wat 'n belangrike rol speel III die ontbindingsproses as fragmenteerders van dooie plantmateriaal III grondekosisteme. Hulle akkumuleer ook kontaminante in hul liggame, veral in die hepatopankreas. Kadmium het geen biologiese funksie nie, en word vrygestel in die omgewing deur verskeie bronne. Sink, aan die ander kant, is een van die essensiële metale en speel 'n belangrike rol in die metabolisme van diere. Sink word ook in die omgewing vrygestel deur 'n verskeidenheid antropogeniese bronne. Die doel van die studie was om deur eksperimentele en veldondersoek die rol van sellulêre veranderinge in die hepatopankreas van terrestriële Isopoda in samehang met ander subietale response te evalueer om by te dra tot die assessering van die impak van kadmium en sink op terrestriële ekosisteme. Porcellio laevis is as toets-spesie in die laboratorium eksperimente gebruik om subietale toksisiteitstoetse mee uit te voer. Kadmium- en sinksulfaat is as kontaminante gebruik, en is apart en gemeng toegedien. Die houtluise is geweeg voor die begin van die blootstellings en elke week deur die loop van die blootstellingsperiode van ses weke. Aan die einde van die blootstellingsperiode is hulle gedissekteer om die hepatopankreas te verwyder. Die sink en kadmium inhoude van die hepatopankreas en res van die liggame van die houtluise is bepaal met behulp van atoomabsorpsiespektrofotometrie. Monsters van die hepatopankreas is ook voorberei vir histologiese analise, en metings van die Persentasie Sellulêre Oppervlak (PSO) is gedoen met behulp van beeldanalise. Eksemplare van Porcellionides pruinosus is versamel van 'n gekontamineerde- en 'n ongekontamineerde gebied. Monster van die hepatopankreas en res van die liggaam van P. pruinosus is ook geanaliseer vir kadmium en sink. Histologiese sneë van die hepatopankreas was ook voorberei en geanaliseer, soos in die laboratorium eksperimente. Blootstelling aan kadmium- en sinksulfaat het die massa van P. laevis negatief beïnvloed in die enkelmetaal-eksperimente. Hierdie twee metale het egter mekaar se effekte in die mengseltoksisiteitstoetse "geneutraliseer". Dit dui op 'n antagonistiese interaksie. Toegediende kadmium- en sinksulfaat het gelei tot die akkumulasie van kadmium en sink in the houtluise, veral in die hepatopankreas. In die mengseltoksisiteitstoetse het kadmium en sink mekaar se akkumulasie beïnvloed. Kadmium- en sinksulfaat, apart of as mengsels toegedien, het die struktuur van die hepatopankreas verander, en dit is kwantitatief aangetoon deur die PSO metings. PSO van die hepatopankreas van houtluise is 'n bruikbare algemene biomerker van blootstelling en effek vir kadmium en sink. Dit word voorgestel dat PSO kan dien as 'n algemene biomerker om negatiewe effekte op die groei of massaverandering van houtluise te voorspel wat aan kadmium en sink mengsels blootgestel word. Die bevindinge van die veldondersoek dui daarop dat PSO gepas mag wees om gebruik te word as 'n algemene biomerker om metaal-geïnduseerde stres by houtluise vanaf 'n gekontamineerde gebied te meet.
20
Genc, Yusuf. "Screening for zinc efficiency in barley (Hordeum vulgare L.)". Title page, table of contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phg324.pdf.
Texto completo da fonteResumo:
Bibliography: leaves 229-250. The aims of the study were to develop a reliable method for screening for Zn efficiency as an alternative to the current field-based methods, and to determine the extent of genotypic variation in tolerance to Zn deficiency in barley.
21
Hsu, Emilie Chia Ching 1979. "Effect of deformation conditions on texture and microstructure of magnesium sheet AZ31". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99768.
Texto completo da fonteResumo:
Magnesium alloys have a great potential in automotive industries, compared to steel and aluminium (Al), Magnesium (Mg) is much lighter and this weight reduction improves fuel efficiency and lowers green gas emission. Due to its hexagonal crystal structure, magnesium has poor ductility at room temperature. Magnesium's ductility improves significantly above about 200°C due to thermal activation of additional slip systems. This has lead to efforts to form auto-body panels with commercial AZ31 magnesium sheet at elevated temperatures. In this work, various AZ31 magnesium alloy materials were used to investigate the influence of deformation conditions on texture and microstructure. Moreover, it is to define the correlation between formability and different deformation mechanisms.It was observed that only basal slip and twinning contributed to room temperature deformation. As deformation temperature increased, an increase in ductility in Mg contributed to dynamic recrystallization occurring readily at elevated temperatures (≥300°C). Even coarse grain material experienced significant tensile elongation due grain refinement. Depending on temperature and strain rate, different deformation mechanisms were activated and lead to different failure modes (moderate necking, cavity, strong necking). More specifically, deformation at elevated temperature in the low-strain-rate regime with stress exponent n about 2-3 and activation energy close to grain-boundary diffusion of Mg (Q = 92 kJ/mol) is characteristic of GBS. Deformation at elevated temperature in the high strain rate regime showed that the stress exponent increased to a value close to 5 and that the activation energy was consistent with the one for Mg self-diffusion (135 kJ/mol) and for diffusion of Al in Mg (143 kJ/mol). This was indicative of a dislocation creep deformation mechanism. Plus the six-fold symmetric patterns of the {1 100} and {1120} pole figures and the splitting of basal plane distribution are another indication of slip mechanism or of dislocation creep mechanism.
The optimum deformation behavior for AZ31 sheet was found to be for the material with fine grain microstructure. The highest elongation of 265% was obtained with the material having initial grain size of 8 mum. In addition, strain-rate sensitivity, which is a good indication of material's ductility, also was the highest in material with 8 mum grain size. As a common trend, the strain-rate sensitivity increased with decreasing strain rate, increasing temperature and decreasing grain size.
In terms of drawability of AZ31 sheet, the deformation controlled by GBS resulted in a fair drawability/formability property with r-value about 1 whereas a deformation mechanism controlled by dislocation creep showed a good drawability with r-value above 1.5. Due to activation of additional slip systems (non-basal and
22
Lo, Wai Hung. "Temperature effect on the composition and the growth of Cadmium zinc sulphide alloy, CdxZn₁-xS". access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21174854a.pdf.
Texto completo da fonteResumo:
Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. On t.p. the "x" of "CdxZn₁-xS" are subscript. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
23
Shang, Lihong. "Effect of microalloying on microstructure and hot working behavior for AZ31 based magnesium alloy". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115880.
Texto completo da fonteResumo:
The formability of Mg alloy sheet in the as-hot rolled condition depends on the microstructure developed during hot rolling. In general, the formability of Mg alloys is improved by finer grain sizes. 'Microalloying' levels of calcium (Ca), strontium (Sr), and cerium (Ce) have been found to refine the as-cast structure, but there is no information as to whether this effect will be reflected in the as-hot worked structure and formability. Thus, in this work, the effects of microalloying levels of calcium (Ca), strontium (Sr), and cerium (Ce) on the microstructures (from as-cast to as-hot rolled) and subsequent hot deformation behavior of AZ31, nominally 3% Al, 1% Zn, and 0.3%Mn, were systematically investigated.To include the effect of solidification rate these alloys were cast in different moulds (preheated steel mould, Cu-mould, and water cooled Cu-mould). One-hit compression testing at temperatures between 250°C ∼ 400 °C, strain rates of 0.001, 0.01, 0.1 s-1 and strains from 0.2 up to 1.0, was performed to investigate the basic hot compression behavior, while two-hit compression testing was conducted to determine the static softening behavior. Hot rolling of the microalloyed AZ31 alloys was then carried out to study the effects of microalloying on as-hot rolled structure under two sets of rolling schedules. To investigate the formability of these microalloyed sheets, tensile tests were completed over a temperature range between ambient and 450°C, at strain rates between 0.1 and 0.0003 s-1.
Results show that Ca and Sr act to refine the as cast grain size and the second phases, consistently promoting fine and uniform as-hot rolled grain structure. With regard to grain refinement, calcium has the strongest effect, whereas Ce is most effective for second phase refinement. In addition, microalloying retards grain growth during hot tensile testing. Multiple alloying presents a combined and complementary effect.
A refined and uniform grain structure combined with well dispersed and thermally stable second phases significantly improves the hot formability of AZ31 sheets by promoting dynamic recrystallization (DRX) in the matrix, resisting grain coarsening, and retarding the development of cavitation and necking. Under the superplastic condition of 450°C and 0.0003 s -1, the elongation was improved by 17% with Ca only, 26% with Ca and Ce, 51% with Ca and Sr, and 59% with Ca, Sr and Ce.
24
Fischer, Axel R., Luisa Sgolik, André Kreller e Christina Dornack. "Zinc(II) Adsorption by Low-Carbon Shungite: The Effect of pH". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-235546.
Texto completo da fonteResumo:
Shungite is a carbonaceous rock which is abundant in Karelia (Russian Federation). Large deposits of shungite with low levels of carbon (approx. 10% C) are also found in Kazakhstan, where it is mined under the trade name Taurit (Koksu Mining Company). Although Taurit has been reported to be used as an adsorbent for hazardous compounds in water treatment, there is very little precise data about its adsorption capacity or the compounds adsorbed. In this study, the ability of Taurit to adsorb Zn(II) was investigated and Freundlich isotherms were determined for both distilled water and tap water. Taurit was found to have a high buffer capacity leading to pH values > 7.0 in aqueous solution. Because dissolved zinc precipitates as Zn(OH)2 under alkaline conditions, the pH must be carefully controlled and kept ≤7.0. Despite the small inner surface area (BET) of Taurit (13.4 m2 g−1), Freundlich coefficients for distilled water (Kf = 2.4, n = 4.0) and tap water (Kf = 1.5, n = 2.5) were similar to other adsorbents. Our results indicate that Taurit could provide a cheap alternative to activated carbon since both substances have a similar adsorption capacity (at least for Zn(II)).
25
Luciani, Rosa Beatriz. "The effect of dissolved atmospheric pollutants on the corrosion of zinc". Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/32775.
Texto completo da fonte
26
Neiman, Alex. "The Effect of Annealing on the Optical Properties of Zinc Oxide". Thesis, University of Canterbury. Department of Physics and Astronomy, 2014. http://hdl.handle.net/10092/9357.
Texto completo da fonteResumo:
Photoluminescence spectroscopy of bulk zinc oxide under different annealing conditions was examined. The effect of the annealing atmosphere, temperature and time on the optical properties of zinc oxide were studied to investigate the influence on the intrinsic defects present. The wafers used were bulk +c ZnO grown by Tokyo Denpa using the hydrothermal technique. The annealing effect on both
zinc and oxygen faces was investigated. The dominant donor bound exciton related to aluminum, labelled in the literature as I₆ demonstrated a splitting of 0.3 meV. The origin of this splitting has been linked to an interaction between aluminum and hydrogen, through its reaction to atmospheric dependent annealing. The removal of the hydrothermal hydrogen peak at 3.3624 eV has uncovered some fine structure. After Arrhenius analysis of this fine structure it was shown it is excited states of bound excitons. This fine structure has been loosely associated with vibrational and rotational excited states. The behaviour of all the optical features present in the photoluminescent spectra under annealing has a relation with the carrier concentration of the samples.
27
Mullins, Anna Lynn. "The Effect of Zinc on L-leucine Transport in Lobster Intestine". UNF Digital Commons, 2009. http://digitalcommons.unf.edu/etd/291.
Texto completo da fonteResumo:
The current study is a characterization of L-leucine absorption across the American lobster intestine in order to determine the likelihood of a bis-complex formation with zinc ([Leu]-Zn-[Leu]) as a possible substrate for PEPT1. This study required isolated lobster intestines to be mounted in a perfusion chamber in order to quantify 3H-L-leucine transport. It was hypothesized that an apical dipeptide transporter, PEPT1, was responsible for uptake of L-leucine via formation of a bis-complex with zinc ([Leu]-Zn-[Leu]) in the form of molecular mimicry, where the bis-complex mimics the normal dipeptide substrate of the proposed carrier system. It was found that L-leucine transport across the lobster intestine was significantly stimulated by luminal zinc and other cations and that this stimulation led to enhanced net flux of the amino acid across the intestine compared to its net flux in the absence of these cations. Transmural transport ofL-leucine was also significantly stimulated by a variety of organic solutes including L-histidine, L-cysteine, and glycylsarcosine (GLY-SAR) by way of countertransport. While many observations in the present study suggest that PEPT1 may be the carrier system responsible for transmural leucine transport in the presence of zinc, other cation-dependent carrier systems, such as the B^0 transporter, with strong transstimulation properties, may also be a suitable candidate for leucine transport in the lobster intestine.
28
D'Souza, Noel Michael. "A Simulation Study of Zinc Oxide Nanowire Field-Effect Transistors (ZnO NWFETs)". University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1227276454.
Texto completo da fonte
29
Siew, Y. H. "Diffusion size effects in zinc". Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370806.
Texto completo da fonte
30
Knies, Katherine A. "Zinc Effects on Mitochondrial Morphology". Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1534854687072296.
Texto completo da fonte
31
Wheal, Matthew Simon. "The influence of chlorsulfuron on the uptake and utilization of zinc by wheat /". Title page, table of contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phw556.pdf.
Texto completo da fonte
32
Ouyang, Ying. "Effect of zinc on the metabolism of thiol-treated human gingival fibroblasts". Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30247.
Texto completo da fonteResumo:
The etiology of periodontal diseases is multifactorial. Cumulative in vivo and in vitro observations implicate volatile sulphur compounds (VSC), namely, hydrogen sulphide (H₂S) and methyl mercaptan (CH₃SH), produced through putrefaction of sulphur-containing proteinaceous substrates by gram negative bacteria, in the pathogenesis of the diseases. Their concentrations in the mouth air correlate with the severity of periodontal involvement. They significantly inhibit total protein, DNA and collagen synthesis, and proline transport in cultured human gingival fibroblast (HGF) systems. The inhibition on total protein synthesis is irreversible, with CH₃SH exerting a more profound inhibitory effect than H₂S. In addition, they have been found to increase the permeability of porcine sublingual mucosa to [3H]-PGE₂, [35S]-SO₄ and E. coli endotoxin thus suggesting that VSC may be capable of altering the permeability of the epithelial barrier and thereby assist the pathogens to gain access to the underlying connective tissues. However, treatment of the mucosa with 0.22% ZnCl₂ totally nullifies the effect of VSC and restores the tissue permeability to control state. The objective of this thesis is to investigate whether zinc is also capable of reversing the inhibitory effect of CH₃SH on total protein, DNA and collagen synthesis, and proline transport by cultured HGF.
While ZnCl₂ at concentration of 0.22% (1.6x10⁻² M) is protective against VSC
and without any apparent harmful effects when applied to the intact tissue, HGF cells, when in direct contact with this agent, are more sensitive to it. In order to determine the maximal zinc concentration that is not deleterious to HGF, studies of total protein synthesis, cell attachment and proliferation were conducted on cultured HGF exposed to various concentrations of ZnCl₂ ranging from 1.0x10⁻⁶M to 1.5x10⁻²M. It was found that zinc at concentrations higher than 1.0x10⁻⁴M significantly decreased the total protein synthesis by HGF over a 24-hr labeling period in DMEM devoid of L-proline but supplemented with L-[′⁴C]-proline. Fibroblast attachment was reduced by 47% and 21% when they were treated with 1.5x10⁻²M and 0.5x10⁻3 M ZnCl₂, respectively. Fibroblasts incubated in the presence of 1.5x10⁻² M and 0.5x10⁻3 M ZnCl₂ failed to proliferate over a 11-day growth period and under the light microscope were rounded in appearance. Transmission electron microscopic studies of fibroblasts treated for 24 hours with different concentrations of ZnCl₂ revealed that cells exposed to higher than 1.0x10⁻⁴M ZnCl₂ underwent pathologic changes characterized by clumping of nuclear chromatin, presence of large amount of myelin figures and overall disintegration of cytoplasmic organelles. In addition, it was found that exposure of HGF cultures for 24 hours to [⁶⁵Zn] resulted in an accumulation of zinc by fibroblasts in a concentration-dependent manner.
To assess the ability of zinc to counteract CH₃SH, control HGF cultures were
incubated in an atmosphere of 95% air / 5% CO₂ while test cultures were subject to
95% air / 5% CO₂ admixed with 15ng / ml CH₃SH with or without the presence of ZnCl₂ in the culture media. It was found that during a 24-hr L-[′⁴C]-proline pulsing period, exposure of HGF to CH₃SH resulted in a 24% reduction in total protein synthesis which
could be totally reversed by the presence of 0.5x10⁻⁴M or 1.0x10⁻⁵ M ZnCl₂ in the media. Furthermore, at these two concentrations, zinc was also found effective in reversing the CH₃SH-induced inhibition of proline transport. HPLC analysis of total protein and collagen confirmed that ZnCl₂ present at a concentration of 1.0x10⁻⁵ M in the media totally nullified the inhibitory effect of CH₃SH and restored total protein synthesis by HGF to control levels. However, at this concentration, ZnCl₂ did not reverse the effect of CH₃SH on collagen synthesis, and at non-inhibitory concentrations (below 0.5x10⁻⁴ M), it was ineffective in reversing the adverse effect of CH₃SH on DNA synthesis by cultured HGF.
In summary, zinc at non-inhibitory concentrations in HGF culture has been shown to be capable of counteracting the CH₃SH-induced suppression of total protein synthesis and proline transport by HGF, which implies that zinc may have a therapeutic role in counteracting some of the adverse effects of volatile thiols and modify their effect on tissue destruction that occurs in periodontal disease.Dentistry, Faculty of
Graduate
33
Shahnaseri, Mahnaz, of Western Sydney Hawkesbury University, of Science Technology and Environment Faculty e School of Food Science. "The effect of cooking method upon iron and zinc bioavailability in rice". THESIS_FST_SFH_Shahnaseri_M.xml, 2001. http://handle.uws.edu.au:8081/1959.7/695.
Texto completo da fonteResumo:
Prevention of iron deficiency rather than treatment is preferred by most nutritionists. The presence of a maximal iron supply is not advised because an excessive or unnecessary iron supplement may have biologically adverse effects, such as impaired immune resistance or negative interaction with other trace elements. All cereals and most vegetables contain phytate (inositol hexaphosphate) which can bind iron and zinc and reduce their biological availability. The amount of iron available for absorption in any given diet depends to a large extent on the composition of the diet, e.g., the presence of vitamin C and haem iron, and the absence of phytate. Rice is one of the most important staples in the Iranian diet and, in fact, rice, for most Iranians, is not a side dish but a main dish to which other foods or ingredients are added. An awareness of the effects of cooking method on nutrient content is important because cooking techniques influence the overall quality of a group's diet. The goal of this study is to determine the bioavailability of iron and zinc in traditional Iranian rice dishes and to assess the effect of traditional methods of cooking rice upon iron and zinc bioavailability. Iranian migrants residing in Sydney were surveyed in order to determine their food habits and traditional cooking methods, for the assessment of their effects upon the bioavailability of iron and zinc in Iranian rice dishes. Rice contains phytate, which is a potent inhibitor of iron absorption. The amount of phytate in rice depends on whether the rice is polished or not. The pre-cooking treatment such as soaking can also influence the phytate content of the rice. Soaking prior to cooking also reduced the amount of ion and zinc. The inhibitory effect of phytate is also overcome by adding different herbs, vegetables and legumes used traditionally in rice dishes cooked by Iranians. Herbs or vegetables such as coriander, parsley and cauliflower, used in Iranian rice dishes, increased the bioavailability iron and zinc. Results obtained from this research show that method of cooking, as well as the food mixture, is very important for the absorption of iron and zinc from the dietDoctor of Philosophy (PhD)
34
Kartasurya, Martha Irene. "Effect of zinc and vitamin A on immune response and respiratory infections /". [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19807.pdf.
Texto completo da fonte
35
Shahnaseri, Mahnaz. "The effect of cooking method upon iron and zinc bioavailability in rice /". View thesis, 2001. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20031120.102309/index.html.
Texto completo da fonteResumo:
Thesis (Ph.D.) -- University of Western Sydney, Hawkesbury, 2001.A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy, Faculty of Science, Technology and Environment, University of Western Sydney, Hawkesbury Campus, 2001. Bibliography : leaves 205-244.
36
Dicks, Dana L. (Dana Lorraine). "The effect of growth hormone treatment on growth in zinc deficient rats /". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56653.
Texto completo da fonteResumo:
The ability of human growth hormone (hGH) to alleviate the effects of zinc deficiency on growth was investigated in the rat. Human GH treatment had no significant effect on food consumption, growth parameters or plasma IGF-I. Food consumption, tail length, liver weight, and tibia weight were significantly lower in the zinc deficient group. Body weight was significantly reduced in the zinc deficient and pair fed groups compared to the control. A significant interaction between zinc and hGH was found for tibial epiphyseal cartilage width but there were no significant differences between the groups receiving hGH and the respective shams. Tissue zinc content and plasma alkaline phosphatase were significantly decreased by the dietary zinc deficiency. Plasma zinc was higher in the groups receiving hGH. Significant interactions between zinc and hGH was found for liver iron, tibial zinc, and tibial copper. Copper and iron showed a competitive interaction with zinc and were lower in the rats receiving the control diet. Both lowered zinc and food intake contributed to the effects of the zinc deficiency; however, these effects were not equally distributed. Food intake had the greater effect on growth and plasma IGF-I while tissue mineral content showed a greater effect for zinc intake.
37
Sultan, Suhana. "Top-down fabrication and characterization of zinc oxide nanowire field effect transistors". Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/354788/.
Texto completo da fonteResumo:
Top-down fabrication is used to produce ZnO nanowires by remote plasma enhanced atomic layer deposition (PEALD) over a SiO2 pillar and anisotropic dry etching. Nanowire field effect transistors (FETs), with channel lengths in the range 18.6 to 1.3 μm, are produced in well-defined locations on a 150 mm diameter silicon wafer. The control of nanowire FET dimensions and locations is seen as the key to wafer-scale nanowire integrated circuit production. Measured electrical results show n-type enhancement behaviour and a breakdown voltage ≥ 75 V at all channel lengths. This is the first report of high voltage operation for ZnO nanowire FETs. Reproducible, well-behaved electrical characteristics are obtained and the drain current scales with 1/L, as expected for long-channel FETs. This thesis reports for the first time that semiconducting quality of ZnO thin film can be achieved using remote PEALD at a minimum temperature of 100oC. Remote PEALD technique offers flexible approach in controlling defects and impurities on the film even at low temperatures which remains a challenge in thermal ALD. Dry etch and remote PEALD processes have been optimised to produce high performance nanowire FET and semiconducting ZnO film. It is demonstrated that using the same CHF3 chemistry, ICP etched nanowires have field-effect mobility six times higher than RIE etched device. The surface roughness from RIE is shown to degrade nanowire FET electrical performance. Experimental results from remote PEALD optimisation show a stoichiometric balanced ZnO film when deposited at substrate temperature of 190oC, zinc precursor dose time of 1s and oxygen plasma time of 4s. Optimized ICP etched nanowire FET with 20 nm width and 10 μm long channel show a high field effect mobility of f 10 cm2/Vs. The electrical results from the pristine state of the nanowires without any post deposition treatments such as passivation demonstrates the feasibility for high performance top-down fabricated NWFETs in line with other unpassivated bottom-up fabricated devices. The effect of atmospheric oxygen adsorption on nanowire surface has been investigated by measuring FET characteristics particularly the threshold voltage shift and hysteresis under different environments and at different gate bias sweep rates. These top-down unpassivated NWFETs are shown to be electrically reproducible when measured in ambient air even after 3 months of fabrication. The device is shown to be electrically air stable with a shift of threshold voltage of less than 11% for unpassivated and only 2% for passivated after 30-days of fabrication. In addition, passivation improves the field effect mobility by a maximum of 4-fold. Unpassivated device measured in vacuum showed a mobility improvement by 1.8 fold. These results show the electronic transport properties of the top-down fabricated nanowires can be influenced by the surface environments. In addition, hysteresis characteristics on top-down fabricated ZnO nanowire devices have been reported for the first time. Hysteresis measurement is sensitive to gate bias sweep rate. The maximum hysteresis obtained for this top-down ZnO NWFET device is 2.2 V, 0.8 V and 1.6 V when measured in ambient air, vacuum and after passivation, respectively. The hysteresis obtained for the unpassivated top-down fabricated ZnO NWFET in this work is smaller compared to other bottom up devices due to better interface quality of remote PEALD ZnO with SiO2 gate dielectric. From this top-down technology, 100 parallel nanowires with channel length of 20 μm are successfully fabricated for biosensing experiments. These devices consistently show n-type enhancement mode characteristics in different solutions. The BSA molecules with negative charges in buffer solution are successfully detected by the channel conductance modulation where the drain current reduced by 12 times. Meanwhile, Lysozyme molecules with positive charges in buffer solution are also successfully detected with an increase of drain current by 21 times. This top-down fabrication approach with low temperature film deposition is promising technology for future low-cost mass manufacturable sensors for health care and biomedical research.
38
Oullette, Margaret Dolliver. "Effect of alcohol ingestion on zinc status and pregnancy outcome in rats /". The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487259580263148.
Texto completo da fonte
39
Atakul, Sevdiye Balköse Devrim. "Synergistic effect of zinc stearate and natural zeolite on PVC thermal stability/". [s.l.]: [s.n.], 2004. http://library.iyte.edu.tr/tezler/master/kimyamuh/T000287.pdf.
Texto completo da fonte
40
Shi, Jian. "Horizontal zinc oxide nanomaterials growth and their application for surface enhanced raman scattering". Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/6682.
Texto completo da fonteResumo:
Thesis (M.S.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 19, 2009) Includes bibliographical references.
41
Gunesekera, Bhadra Manel. "Effect of dietary zinc or pyridoxine deficiency upon estrogen directed gene expression in the rat uterus". Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39799.
Texto completo da fonteResumo:
In the present study the effect of diets restricted in either zinc or pyridoxine upon estrogen directed gene expression in the mature rat uterus was tested. Sexually mature female rats were maintained on zinc-adequate (40 mg/kg diet) ad libitum or restricted-fed, pyridoxine-deficient, or zinc-deficient ( < 1 mg/kg diet or 3mg/kg diet) ad libitum-fed diets for 35 days. All animals were bilaterally ovariectomized and used for experimentation at 14 days post ovariectomy. On day 35 each rat was injected intraperitoneally with estrogen. They were killed at different times post injection and thymidine kinase (TK, EC 2.7.1.21) or creatine kinase (CK, EC 2.7.3.2) activity was assayed in uteri cytosol fractions. In addition the steady state level of ckb mRNA in uteri cytosol fractions was measured following estrogen administration.
The weight gain of the rats fed the low zinc and low pyridoxine diets was significantly lower than those fed the zinc-adequate diet ad libitum. The consumption of the zinc-deficient diet resulted in a significant decrease in plasma zinc while a pyridoxine deficient diet produced a significant reduction in plasma pyridoxine. Vehicle-injected uterine TK activity was 2-3 pmoles of d-TMP/min/mg protein. The TK activity was significantly increased (p < 0.05) 42 h post estrogen injection on the zinc-adequate diet ad libitum and pair-wt fed rats. This activity was sustained at 48 h post injection prior to declining to control values within 60 h. The maximum (4-fold) increase occurred at 36 h post estrogen injection in pyridoxine-deficient rats which was sustained at 42 & 48 h. The increase in uterine TK activity was 3-fold at 42 hand 48 h post injection. However this increase was not significantly different from the peak value seen in zinc-adequate and pyridoxine-deficient diet fed rats. No measurable effect of estrogen on CK activity was observed on the zinc adequate or zinc-deficient diet fed rats using a coupled enzyme assay. However the time course of ckb mRNA induction on the zinc-adequate pair-wt fed rats following estrogen administration paralleled the time course of estrogen induced protein (IP) synthesis previously observed by Gorski et al. (1970). IP is now known to be the brain type isoenzyme of creatine kinase. An induction of ckb mRNA between 0-3 h post estrogen injection was not observed on the zinc-deficient diet fed rats. However in a subsequent experiment an induction of uterine ckb mRNA 2 h following estrogen administration was observed in zinc-deficient rats. The possible reasons for this discrepancy are discussed.
Zinc ions are known to be required to enable the estrogen receptor complex to bind to DNA and initiate transcription. It has been hypothesized that inadequate provision of dietary zinc may therefore reduce compliance to estrogen directed gene expression by limiting the efficiency of recruitment of zinc ions for stabilization of the zinc finger of the steroid receptor. The results of the present study failed to support this hypothesis at this moderate level of zinc depletion.Ph. D.
42
Komatsu, Camila Gomes [UNESP]. "Estado nutricional e perfil bioquímico de zinco e selênio em pacientes com deficiência de UgA". Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/88339.
Texto completo da fonteResumo:
Made available in DSpace on 2014-06-11T19:23:25Z (GMT). No. of bitstreams: 0
Previous issue date: 2012-12-14Bitstream added on 2014-06-13T18:50:30Z : No. of bitstreams: 1
komatsu_cg_me_arafcf_parcial.pdf: 79141 bytes, checksum: 0b4eb56ed80953314f75746a43311a53 (MD5) Bitstreams deleted on 2015-02-09T14:35:40Z: komatsu_cg_me_arafcf_parcial.pdf,Bitstream added on 2015-02-09T14:36:21Z : No. of bitstreams: 1
000706724.pdf: 336800 bytes, checksum: 23a7e4a01cf8ec0c9124706da993a93a (MD5) Bitstreams deleted on 2015-02-09T17:15:03Z: 000706724.pdf,Bitstream added on 2015-02-09T17:15:40Z : No. of bitstreams: 1
000706724.pdf: 336800 bytes, checksum: 23a7e4a01cf8ec0c9124706da993a93a (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Universidade Estadual Paulista (UNESP)
A deficiência da imunoglobulina A (IgA) é definida como níveis séricos de IgA menores que 7mg/dL na presença de níveis séricos normais de IgG e IgM em indivíduos com idade maior que 4 anos. Seus sintomas podem estar associados com doenças como alergias, auto-imunidade, neoplasias e infecções. Diversos nutrientes têm sido descritos por exercerem papel no sistema imunológico, entre eles os minerais zinco e selênio. A deficiência do zinco pode comprometer o sistema imunológico e aumentar a suscetibilidade para doenças graves. Há comprometimento tanto da imunidade inata quanto adaptativa, aumentando a suscetibilidade a infecções por vários patógenos.O selênio é essencial para o funcionamento eficiente de muitos aspectos do sistema imunológico em humanos, e suas funções provavelmente são derivadas das proteínas contendo selênio (selenoproteínas). O presente estudo teve por objetivo avaliar os perfis antropométrico, bioquímico, nutricional e o status de zinco e selênio de pacientes deficientes em IgA, bem como avaliar uma possível correlação entre os micronutrientes avaliados com o estado nutricional. Somente 1 indivíduo apresentou déficit nutricional em relação à antropometria. O consumo de zinco se mostrou adequado em quase toda a amostra (75% das crianças, adolescentes e adultos), assim como ocorreu com o selênio (87,5% de todos os indivíduos), o que condiz com os níveis plasmáticos dos minerais (com níveis adequados de selênio em todos os participantes e de zinco em quase todos). Entretanto, os níveis eritrocitários mostram deficiência de ambos os oligoelementos. Apesar de a amostra estudada não apresentar déficit nutricional relativo à antropometria, há deficiência dos minerais analisados nos eritrócitos
The deficiency of immunoglobulin A (IgA) is defined as serum IgA levels lower than 7mg/dL in the presence of normal serum IgG and IgM levels in individuals older than four years. Your symptoms may be associated with diseases such as allergies, autoimmunity, cancer and infections.Several nutrients have been described by exercising role in the immune system, including the minerals zinc and selenium.The zinc deficiency can compromise the immune system and increase susceptibility to serious illnesses. Both innate and adaptive immunity are compromised, increasing susceptibility to infection by various pathogens. Selenium is essential for the efficient operation of many aspects of the immune system in humans, and their functions are probably derived from proteins containing selenium (selenoproteins). The present study aimed to evaluate the anthropometric, biochemical, and nutritional profiles and the status of zinc and selenium in IgA-deficient patients, and to evaluate a possible correlation between the micronutrients assessed nutritional status.Only one subject showed malnutrition in relation to anthropometry. The zinc intake was adequate in almost the entire sample (75% of children, adolescents and adults), as with selenium (87.5% of all individuals), which is consistent with the plasma levels of minerals (with adequate levels of selenium in all participants and zinc in almost all). However, levels of both trace elements were deficient in the erythrocyte. Although the sample has not shown nutritional deficit based on anthropometry, there is a deficiency of minerals analyzed in erythrocytes
43
Komatsu, Camila Gomes. "Estado nutricional e perfil bioquímico de zinco e selênio em pacientes com deficiência de UgA /". Araraquara : [s.n.], 2012. http://hdl.handle.net/11449/88339.
Texto completo da fonteResumo:
Orientador: Anderson Marliere NavarroBanca: Flávia Queiroga Aranha de Almeida
Banca: Telma Maria Braga Costa
Resumo: A deficiência da imunoglobulina A (IgA) é definida como níveis séricos de IgA menores que 7mg/dL na presença de níveis séricos normais de IgG e IgM em indivíduos com idade maior que 4 anos. Seus sintomas podem estar associados com doenças como alergias, auto-imunidade, neoplasias e infecções. Diversos nutrientes têm sido descritos por exercerem papel no sistema imunológico, entre eles os minerais zinco e selênio. A deficiência do zinco pode comprometer o sistema imunológico e aumentar a suscetibilidade para doenças graves. Há comprometimento tanto da imunidade inata quanto adaptativa, aumentando a suscetibilidade a infecções por vários patógenos.O selênio é essencial para o funcionamento eficiente de muitos aspectos do sistema imunológico em humanos, e suas funções provavelmente são derivadas das proteínas contendo selênio (selenoproteínas). O presente estudo teve por objetivo avaliar os perfis antropométrico, bioquímico, nutricional e o status de zinco e selênio de pacientes deficientes em IgA, bem como avaliar uma possível correlação entre os micronutrientes avaliados com o estado nutricional. Somente 1 indivíduo apresentou déficit nutricional em relação à antropometria. O consumo de zinco se mostrou adequado em quase toda a amostra (75% das crianças, adolescentes e adultos), assim como ocorreu com o selênio (87,5% de todos os indivíduos), o que condiz com os níveis plasmáticos dos minerais (com níveis adequados de selênio em todos os participantes e de zinco em quase todos). Entretanto, os níveis eritrocitários mostram deficiência de ambos os oligoelementos. Apesar de a amostra estudada não apresentar déficit nutricional relativo à antropometria, há deficiência dos minerais analisados nos eritrócitos
Abstract: The deficiency of immunoglobulin A (IgA) is defined as serum IgA levels lower than 7mg/dL in the presence of normal serum IgG and IgM levels in individuals older than four years. Your symptoms may be associated with diseases such as allergies, autoimmunity, cancer and infections.Several nutrients have been described by exercising role in the immune system, including the minerals zinc and selenium.The zinc deficiency can compromise the immune system and increase susceptibility to serious illnesses. Both innate and adaptive immunity are compromised, increasing susceptibility to infection by various pathogens. Selenium is essential for the efficient operation of many aspects of the immune system in humans, and their functions are probably derived from proteins containing selenium (selenoproteins). The present study aimed to evaluate the anthropometric, biochemical, and nutritional profiles and the status of zinc and selenium in IgA-deficient patients, and to evaluate a possible correlation between the micronutrients assessed nutritional status.Only one subject showed malnutrition in relation to anthropometry. The zinc intake was adequate in almost the entire sample (75% of children, adolescents and adults), as with selenium (87.5% of all individuals), which is consistent with the plasma levels of minerals (with adequate levels of selenium in all participants and zinc in almost all). However, levels of both trace elements were deficient in the erythrocyte. Although the sample has not shown nutritional deficit based on anthropometry, there is a deficiency of minerals analyzed in erythrocytes
Mestre
44
Cassells, Kevin D. "The effect of sample rotation on the lubrication of zinc dialkydithiophosphate additive formulations". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28547.pdf.
Texto completo da fonte
45
Ghazali, Nor Azlin. "Design, fabrication and characterization of high performance zinc oxide nanowire field-effect transistors". Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/427139/.
Texto completo da fonteResumo:
This research project is focused on the optimization and electrical enhancement of zinc oxide (ZnO) nanowire field-effect transistors by remote plasma atomic layer deposition. Three device configurations have been fabricated based on a top-down fabrication method with channel lengths in the range of 18.6 μm to 1.3 μm. These devices were produced in well-defined locations on a 150 mm diameter silicon wafer. Controllable nanowire FET dimensions and locations are seen as fundamental to wafer-scale nanowire integrated circuit fabrication. Measured electrical results show n-type depletion behaviour with good electrical characteristics for all device configurations. The first device configuration was fabricated with optimization of a top-down process based on a spacer method, aiming to reduce the sidewall roughness of the nanowire. The approach included the top-down nanowire process with reduced sidewall roughness during pattern transfer and the improvement of the electrical characteristics. The process involved a photoresist reflow technique and dry oxidation of the etched silicon sidewalls. The optimized top-down fabrication and sidewall resist smoothing were shown to produce ZnO nanowire FETs with good electrical characteristics for channel length devices of 1.3 μm, 8.6 μm, and 18.6 μm. The optimized device is able to produce a high output drain current by a factor of three, steep subthreshold slope of 800 mV/decade and a transconductance value of 5.9 nS, which is two times higher than the device from an un-optimized fabrication process. In the second device configuration, the aim was to improve the contact resistance between the ZnO nanowire channel and source/drain contact as well as the mobility of the ZnO nanowire FET. Enhanced performance of the ZnO nanowire FET is demonstrated by depositing an Al-doped ZnO (AZO) thin film between the ZnO nanowires and the source/drain aluminium contact. This highly conductive AZO thin film is deposited via a thermal atomic layer deposition (ALD) at 200 oC and forms a bi-layer source/drain contact. The contact resistance was reduced from 194.1 Ω with aluminium contact to only 9.6 Ω using AZO. The field-effect mobility of ZnO nanowire FETs with AZO increases from 3.5 cm2/Vs to 85.7 cm2/Vs in dual nanowires. The AZO layer is seen as a promising source/drain contact material for the fabrication of high performance ZnO nanowire FETs. The ZnO nanowire FET with AZO thin film as the source/drain contact is further investigated by measuring the temperature-dependant electrical characteristics. The transfer curves shows a parallel shift toward negative voltage as the temperature increased from 200 K to 300 K. In the third device configuration, the new fabrication method using direct photolithography and lateral wet etching was used to simplify the fabrication of top-down ZnO nanowire FETs and to avoid the disadvantage of the spacer method. This particular method is a preliminary attempt towards achieving high electrical performance in ZnO nanowire FETs for RF and logic circuit applications. This novel technique allows for the formation of nanowire FET with minimal impact from ions and chemical radicals during the anisotropic dry etching process. Except for the low field-effect mobility, this experiment demonstrated desirable electrical characteristics. Bottom-gate ZnO nanowire FETs with different gate lengths show a threshold voltage between -0.7 V to 1.5 V, on/off current ratio up to 107 and a subthreshold swing between 200 mV/decade to 300 mV/decade. This top-down fabrication method with low temperature film deposition encourages further research regarding the RF characterization of ZnO nanowire FETs and the adaptability of a RF device using ZnO nanowire FETs.
46
Deka, Priyanka. "The Effect of Zinc Oxide Nanoparticles on Plants, and on Host-Pathogen Interactions". Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/29270.
Texto completo da fonteResumo:
Zinc oxide nanoparticles (ZnO NPs) are a type of engineered nanomaterial that is currently being explored for use in different aspects of agriculture. So far, research on this area is limited to evaluating the phenotypical responses of plants to a high concentration of the NPs which is realistically not feasible in the actual environment. This research aims to investigate the molecular-level interactions between ZnO NPs and plants, together with another significant component of the environment, a fungal plant pathogen. Prior to studying these molecular-level interactions, the uptake of ZnO NPs in planta was validated using a fluorescent zinc ion sensor, Zinpyr-1 and a zinc ion chelator, TPEN in confocal laser scanning microscopy (CLSM) and Transmission Electron Microscopy (TEM). Phenotypical effects were studied in soybean plants exposed to environmentally relevant concentrations of ZnO NPs and bioaccumulation of zinc was studied in seeds of soybean and other soy products. The next phase of this research focused on investigating the physiological responses of plants exposed to ZnO NPs. This was achieved by elucidating the complete transcriptome of the plants using a Next Generation sequencing (NGS) platform, RNA seq. A significant part of this research emphasized on exploring the effects of ZnO NPs on host-pathogen interactions. The model monocot plant, barley was used in this study, together with a necrotrophic pathogen, Pyrenophora teres f. teres (Ptt). The barley line which was used, CI5791 is resistant to the disease Net Form Net Blotch (NFNB), caused by Ptt. Rapid responses of plants to ZnO NPs were observed that subsided at the later time-points, whereas the heightened responses to the pathogen alone (P) and combined application (ZnO NP + P) persisted. Exposure to ZnO NPs also induced transcriptional reprogramming in the Ptt inoculated plant that resulted in compromised immunity in the otherwise resistant barley, due to the persistence of salicylic acid (SA)-related genes. In ZnO NP-exposed Arabidopsis thaliana, the effects were contradictory. From the barley and Arabidopsis expression data, it could be concluded that both species react differently to ZnO NPs, giving a glimpse of the differential responses that ZnO NPs may elicit in different plant species.USDA-NIFA
National Science Foundation (NSF)
47
Lyimo, Germana Vincent. "Green synthesised Zinc Oxide Nanoparticles and their antifungal effect on Candida albicans Biofilms". University of Western Cape, 2020. http://hdl.handle.net/11394/7606.
Texto completo da fonteResumo:
Magister Scientiae Dentium - MSc(Dent)Candida albicans is a clinical fungal isolate that is most frequently isolated from different host niches, and is implicated in the pathogenesis of several fungal infections, including oral candidiasis. The pathogenesis and antifungal resistance mechanisms of Candida species are complex and involve several pathways and genes. Oral candidiasis incidence rates are rapidly increasing, and the increase in resistance to conventional antifungals has led to the need to develop innocuous and more efficacious treatment modalities. The purpose of this study was to explore a single pot process for phytosynthesis of zinc oxide nanoparticles (GZnO NPs) and to assess their antifungal potential.
48
Saaka, Mahama. "Effect of prenatal zinc supplementation on malarial morbidity, pregnancy anaemia and birth weight". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2007. https://ro.ecu.edu.au/theses/281.
Texto completo da fonteResumo:
Anaemia and malaria are two related problems of public health significance in malaria endemic countries including Ghana that continue to impact negatively on pregnancy outcomes, despite interventions being put in place to address them. The reasons for the apparent lack of efficacy of routine iron supplementation in reducing the risks of preterm and other adverse pregnancy outcomes are not clearly established in Ghana. It is not also known whether all pregnant women benefit from iron supplementation and whether there are some other factors that limit the effectiveness of prenatal iron supplementation. This study tested the primary hypothesis that prenatal zinc supplementation in combination with malaria prophylaxis and an iron and folic acid intervention package in a zinc-deficient and malaria-edemic population will increase mean birth weight.
49
Singbo, Arnaud. "The effect of zinc and soil ph on grain yield and nutrient concentrations in spring wheat cultivated on potted soil". Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2845.
Texto completo da fonteResumo:
Thesis (MTech (Agriculture))--Cape Peninsula University of Technology, 2018.Zinc deficiency on various soil types have been reported in arable soils of sub Saharan Africa (SSA) including South Africa. A pot trial was conducted at the Cape Peninsula University of Technology, Wellington campus to investigate the interaction of different application rates of Zn at various soil pH on the grain yield and quality of spring wheat in a completely randomized factorial design replicated three times. The four soil pH tested were: pHA: 5.1, pHB: 5.6, pHC: 6.1, pHD: 6.6 which correspond to lime application at 0, 0.5, 1 and 1.5 t/ha. Five Zn rates (Zn1: 3.5; Zn2: 4.5; Zn3: 5.5 Zn4: 6.5, and Zn5: 7.5 mg /kg soil which correspond to Zn1: 7; Zn2: 9; Zn3: 11; Zn4: 13 and Zn5: 15 kg /ha) were applied at two (planting and flowering) growth stages. Yield and yield component data collected were analyzed using SAS version 9.2 and means were separated by Duncun’s Multiple Range Test (DMRT). The results showed that grain yield and yield components were significantly affected by lime application pHC (6.1): 1t/ha at planting. Zn application at planting had no significant effect on the grain yield and yield components. However, at flowering, the simultaneous increase of Zn along with increase in lime positively affected grain yield and yield components. Plant analysis showed that at both stages (planting and flowering), Zn application, especially at pH 6.6, significantly increased P, K, Ca, Na, Mg Fe, Cu and B concentrations in wheat grain, but the concentrations of N, Mn, Zn and protein remained unaffected. Zn application had no effect on most nutrients due to the presence of lime. While the absence of lime, Zn4: 6.5mg/kg (corresponding to 13kg/ha) significantly increased the nutrients. In addition, Zn3: 5.5mg/kg (corresponding to 11kg/ha) promoted Zn absorption by grain in all treatments.
50
Ramesh, Sunita. "Molecular mechanism of zinc uptake and regulation in cereals". Title page, table of contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phr1724.pdf.
Texto completo da fonteResumo:
Bibliography: leaves 174-204. "This work provides a starting point for understanding the molecular mechanisms of zinc uptake and the regulation of zinc transport in cereals. Zinc efficient cereals would yield more on soild with low zinc and could potentially result in increased zinc content grain."