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Artigos de revistas sobre o assunto "Copper accumulation"
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Tsekova, K. V., P. G. Marinov e A. N. Tzekova. "Copper accumulation byAspergillus awamori". Folia Microbiologica 45, n.º 3 (junho de 2000): 217–20. http://dx.doi.org/10.1007/bf02908947.
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Thornburg, Larry P. "A Perspective on Copper and Liver Disease in the Dog". Journal of Veterinary Diagnostic Investigation 12, n.º 2 (março de 2000): 101–10. http://dx.doi.org/10.1177/104063870001200201.
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Copper is a ubiquitous trace metal necessary for normal function of a variety of cellular proteins. Intracellular copper metabolism is complex, and only a few of the proteins/genes involved are known. Copper deficiency does not appear to be a clinical problem in dogs. Excess copper accumulation in the liver as a cause of hepatitis and cirrhosis was first demonstrated among Bedlington terriers. Subsequently, copper accumulation in the liver has been shown to occur in several other breeds of dogs. Excess hepatic copper has been found in dogs with normal liver histology, dogs with hepatitis, and dogs with end stage cirrhosis. Evidence is accumulating that copper is a cause of liver disease in breeds of dogs other than Bedlington terriers. Moreover, as more data are accumulated, the copper storage disease appears to have characteristics that are very similar among all of the affected breeds.
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Scheiber, Ivo F., Julian F. B. Mercer e Ralf Dringen. "Copper accumulation by cultured astrocytes". Neurochemistry International 56, n.º 3 (fevereiro de 2010): 451–60. http://dx.doi.org/10.1016/j.neuint.2009.12.002.
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Vulpe, Constantina Bianca, Mariana Adina Matica, Renata Kovačević, Daniela Dascalu, Zoran Stevanovic, Adriana Isvoran, Vasile Ostafe e Gheorghița Menghiu. "Copper Accumulation Efficiency in Different Recombinant Microorganism Strains Available for Bioremediation of Heavy Metal-Polluted Waters". International Journal of Molecular Sciences 24, n.º 8 (20 de abril de 2023): 7575. http://dx.doi.org/10.3390/ijms24087575.
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The aim of this research was to investigate the bioremediation conditions of copper in synthetic water. In the present study, copper ions accumulation efficiency was determined using various genetically modified strains of Saccharomyces cerevisiae (EBY100, INVSc1, BJ5465, and GRF18), Pichia pastoris (X-33, KM71H), Escherichia coli (XL10 Gold, DH5α, and six types of BL21 (DE3)), and Escherichia coli BL21 (DE3) OverExpress expressing two different peroxidases. Viability tests of yeast and bacterial strains showed that bacteria are viable at copper concentrations up to 2.5 mM and yeasts up to 10 mM. Optical emission spectrometry with inductively coupled plasma analysis showed that the tolerance of bacterial strains on media containing 1 mM copper was lower than the tolerance of yeast strains at the same copper concentration. The E. coli BL21 RIL strain had the best copper accumulation efficiency (4.79 mg/L of culture normalized at an optical density of 1.00), which was 1250 times more efficient than the control strain. The yeast strain S. cerevisiae BJ5465 was the most efficient in copper accumulation out of a total of six yeast strains used, accumulating over 400 times more than the negative control strain. In addition, E. coli cells that internally expressed recombinant peroxidase from Thermobifida fusca were able to accumulate 400-fold more copper than cells that produced periplasmic recombinant peroxidases.
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Herd, S. M., J. Camakaris, R. Christofferson, P. Wookey e D. M. Danks. "Uptake and efflux of copper-64 in Menkes'-disease and normal continuous lymphoid cell lines". Biochemical Journal 247, n.º 2 (15 de outubro de 1987): 341–47. http://dx.doi.org/10.1042/bj2470341.
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The accumulation of copper over 2 h by normal lymphoid cells and those from Menkes'-disease patients (Menkes' cells) was found to be biphasic, with an initial phase of rapid uptake, an approach to steady state at around 40-60 min, followed by a further accumulation phase. The accumulation of copper was not diminished by the addition of a variety of metabolic inhibitors, suggesting that copper uptake is not an active process. The presence of carbonyl cyanide m-chlorophenylhydrazone in the culture medium stimulated the uptake and accumulation of copper in both normal and Menkes' cells to the same absolute level. This effect appeared to be specific for copper, since the accumulation of Zn and Cd was unaffected. Menkes' cells did not differ from normal in their initial rate of copper uptake. Analysis of the uptake curve suggested that the membrane transport of copper involves both passive and facilitated diffusion. Initial rate of efflux from the cells was approximated by two methods. Menkes' cells did not appear to be affected in this function. It seems likely that the basic defect in Menkes' disease involves a step in intracellular copper transport rather than the membrane transport of copper.
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Richard, Julianne N., Jennifer E. Graham, Sharon A. Center, Michael M. Garner e Drury R. Reavill. "Hepatic copper accumulates in ferrets with and without hepatobiliary disease". American Journal of Veterinary Research 83, n.º 4 (1 de abril de 2022): 371–80. http://dx.doi.org/10.2460/ajvr.21.08.0131.
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Abstract OBJECTIVE To determine hepatic copper concentrations and zonal distribution in ferrets with and without hepatobiliary disease, validate rhodanine-based qualitative copper scoring and digital copper quantification in ferret hepatic samples, and ascertain whether clinical features predicted copper accumulation. ANIMALS 34 ferrets, including 7 with necroinflammatory disease, 5 with hepatocellular carcinoma, 13 with non-necroinflammatory disease, and 9 with no hepatobiliary disease. PROCEDURES Rhodanine-based digital copper quantification was validated by use of liver dually measured by atomic absorption spectroscopy and digital scanning (R2 = 0.98). Clinical features and hepatic copper scores and concentrations (dry weight liver) were compared between groups. Zonal copper distribution was determined. RESULTS Hepatic copper concentration was strongly correlated with copper scores (ρ = 0.88). Ferrets with hepatobiliary disease were significantly older and had significantly higher serum alkaline phosphatase and γ-glutamyltransferase activities and creatinine concentrations. Centrilobular copper accumulated in 23 of 34 (64%) ferrets with (n = 15) and without (8) hepatobiliary disease. Median copper concentrations were not significantly different between ferrets with and without hepatobiliary disease but were significantly higher within neoplastic hepatic tissue in ferrets with hepatocellular carcinoma. Hepatic copper concentrations exceeded feline (> 180 µg/g) and canine (> 400 µg/g) reference limits in 19 and 9 ferrets, respectively. Hepatic copper > 1,000 µg/g occurred in 5 ferrets with and 2 without hepatobiliary disease. Clinical features did not predict copper accumulation. CLINICAL RELEVANCE Rhodanine-based digital copper quantification and qualitative copper scoring discerned liver copper accumulation in ferrets. Ferrets with and without hepatobiliary disease displayed a propensity for centrilobular hepatic copper accumulation of uncertain clinical importance. Clinical and clinicopathologic features could not exclusively implicate pathologic copper accumulation.
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Haywood, S., H. C. Rutgers e M. K. Christian. "Hepatitis and Copper Accumulation in Skye Terriers". Veterinary Pathology 25, n.º 6 (novembro de 1988): 408–14. http://dx.doi.org/10.1177/030098588802500602.
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Livers of nine related Skye terriers with liver disease were evaluated for histological changes and copper content. Lesions ranged from hepatocellular degeneration and necrosis (zone 3) with intracanalicular cholestasis and mild inflammation, to chronic hepatitis with cholangioplasia and cirrhosis. Excess copper (801–2,257 μg/g) was related to the severity of cholestasis. Skye terrier hepatitis is a distinct disease entity and may be derived from a disorder of intracellular bile metabolism culminating in disturbed bile secretion and the accumulation of copper.
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Toselli, M., P. Schiatti, D. Ara, A. Bertacchini e M. Quartieri. "The accumulation of copper in soils of the Italian region Emilia-Romagna". Plant, Soil and Environment 55, No. 2 (24 de fevereiro de 2009): 74–79. http://dx.doi.org/10.17221/317-pse.
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The investigation was carried out in 2005, on 30 plots chosen in the Central-Eastern part of the Emilia Romagna region, and cultivated with pear, grapevine and vegetable crops under the organic management system. For each crop, 5 plots with a level of calcium carbonate > 10% and 5 plots with a level of calcium carbonate < 3% were selected. For pear and vine, soil analyses were performed at the depths of 0–20 cm and 20–50 cm, for vegetable at the depth of 0–50 cm. Organic matter content was higher in pear-cultivated plots, followed by grapevine and vegetable crops. Copper application rate, from 1998 to 2004, was higher in pear and grapevine than in vegetable plots. Soil total and DTPA-extractable Cu were higher in pear and grapevine than in vegetable-cultivated plots. Soil DTPA-extractable Cu concentration was higher in the upper horizon than at 20–50 cm soil depth. The increase of total Cu in pear and vine-cultivated plots was combined with the increase of soil inactive Cu.
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Mitani, Tomoyo, e Dragoslav M. Misic. "Copper accumulation byPenicilliumsp. isolated from soil". Soil Science and Plant Nutrition 37, n.º 2 (junho de 1991): 347–49. http://dx.doi.org/10.1080/00380768.1991.10415045.
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Tsekova, Kolishka, Danka Galabova e Kristina Todorova. "Copper Accumulation and Phosphatase Activities of Aspergillus and Rhizopus". Zeitschrift für Naturforschung C 55, n.º 9-10 (1 de outubro de 2000): 708–12. http://dx.doi.org/10.1515/znc-2000-9-1007.
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Abstract Copper accumulation and phosphatase activities of three Aspergillus species resistant to copper were compared to three copper-sensitive Rhizopus species. High level of acid phosphatases and decreased Cu2+-uptake were found with resistant in contrast to sensitive strains. The presence of copper(II) ions in the medium increased the production of acid phosphatases in the resistant A. niger and decreased their activity in the sensitive R. delemar. Copper ions inhibited the activity of A. niger cellular acid phosphatase with a Ki of 8.9x10-4 ᴍ and slightly activated the R. delemar enzyme.
Teses / dissertações sobre o assunto "Copper accumulation"
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Blanchard, Jonathan. "Copper Toxicity and Accumulation: Physiology, Chemistry, and Molecular Biology". Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/284.
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Our knowledge of aquatic Cu toxicity has increased greatly over the past several years culminating with the incorporation of a model (the Biotic Ligand Model (BLM)) into the regulatory framework which allows for the site specific adjustment of water quality criteria based on water chemistry. However, our understanding of Cu toxicity in the aquatic environment is limited mostly to freshwater (FW). Because of this limited knowledge, this dissertation set out to examine the affect of salinity on Cu toxicity and accumulation across salinities from FW to sea water (SW). First, this work examined tissue specific Cu accumulation in five salinities (FW, 5 ppt, 11 ppt, 20 ppt, 28 ppt) from waterborne Cu exposure at two [Cu] (30 and 150 µg Cu L-1) in the euryhaline killifish, Fundulus heteroclitus. Branchial and hepatic accumulation followed a pattern that would be expected based on speciation and competition from cations. [Cu] were high in FW and decreased as salinity increased. However, in the intestine, [Cu] were highest at 5 ppt and were also elevated in the higher salinities. The elevation at the higher salinities was most likely due to drinking by the fish which increases as salinity increases above the isoosmotic point of the fish (~10 ppt) for osmoregulatory purposes and showed a trend toward increasing [Cu] with increasing salinity as would be expected. Secondly, the mechanism of Cu toxicity in FW and SW was examined in killifish. The mechanism of Cu toxicity in the killifish in FW was the same as had been seen for other FW fish. Cu exposure caused a decrease in Na+ / K+ ATPase activity which led to a decrease in whole body [Na+] which is the likely cause of death. In SW, surprisingly no ionoregulatory disturbances were observed. The only measured parameter that was changed in SW was net ammonia which showed a substantial decrease. Therefore, the mechanism of acute copper toxicity in FW and SW differed suggesting that physiology may need to be considered in future development of a BLM for SW. Next, the effect of salinity on Cu accumulation from a naturally incorporated dietary source was examined in FW and SW in Fundulus heteroclitus. Cu accumulation was not seen to differ in the two salinities in spite of differences in gut fluid chemistry that would lead to an ~11 fold difference in free Cu ion between FW and SW. This indicated that Cu accumulation from a dietary source was not as the free ion but most likely as organically (amino acid) bound Cu. In addition to this, subcellular fractionation of the diet revealed that Cu available to the next trophic level did not change with increasing waterborne [Cu], increasing tissue [Cu], or time in oysters which has implications for Cu accumulation in the environment. Finally, the molecular mechanisms behind effects and acclimation to waterborne and dietary Cu exposure in FW and SW were examined using suppression subtraction hybridization in the killifish intestine. Exposure to Cu induced a stress response which could be responsible for upregulation of genes involved in protein synthesis, proteolysis and ATP production. At the tissue level, two main responses were observed. First, genes necessary for muscle function were upregulated potentially in response to previously observed decreased intestinal motility. Secondly, apoptotic genes were upregulated corresponding to increased rates of apoptosis in intestines during dietary exposures. At the cellular level, metal chelators and oxidative stress genes were upregulated in response to increased free Cu in the cell and the subsequent free metal induce free radical formation. This work has advanced our understanding of Cu toxicology in saline environments and emphasized the importance of considering both chemistry and physiology in analyzing and interpreting Cu toxicology especially in saline environments. Hopefully, it will contribute to the future development of Cu water quality criteria.
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HAYASHI, HISAO, TOSHIKUNI TAKIKAWA, MOTOHIRO ARAO, JUNSUKE KURIKI, SHOSHI KATO, NOBUO SAKAMOTO, MOTOYOSHI YANO, AKIRA YAGI e HIROTOMO TAKESHIMA. "Hepatic Copper Accumulation in Patients with Primary Biliary Cirrhosis". Nagoya University School of Medicine, 1993. http://hdl.handle.net/2237/17541.
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Blair, Brian G. "Copper Transporter 2 (CTR2) as a regulator of cisplatin accumulation and sensitivity". Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3386764.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed Jan. 19, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 132-148).
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Leighton, Margaret Janet. "The accumulation and subcellular localization of copper in the liver of foetal deer". Thesis, Royal Veterinary College (University of London), 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519519.
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Larson, Christopher Alan. "The role of copper transporter 1 (CTR1) in the cellular accumulation of platinum drugs". Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/ucsd/fullcit?p3404158.
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Thesis (Ph. D.)--University of California, San Diego, 2010.Title from first page of PDF file (viewed June 3, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (leaves 108-118).
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Bradley, Matthew Darren. "The accumulation and toxicity of copper, zinc and manganese in the farmed snail Helix aspersa maxima". Thesis, Bangor University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307215.
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Galyas, Éva. "Concentrations of lead, copper and zinc in forest soils near industrial areas". Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-40363.
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Environmental contamination with heavy metals, especially of soils, has been a continuousproblem worldwide since the beginning of the industrial revolution. Heavy metal emissionshave increased continuously since 1900 and the metals accumulate in the environment. Pulpand paper mill factories, and factories which produce sulphuric acid emit heavy metals,among others lead (Pb), copper (Cu) and zinc (Zn). Results from previous studies showedthat the soils near factories had higher concentrations of these pollutants than the controlplace. In this study I want to determine the effects of industrial heavy metal emissions of onehistoric and one present industry on nearby soil heavy metal concentrations.Samples were taken near one historically heavily contaminated site, the old sulphite factoryin Rydöbruk (1897-1944) and near the present Stora Enso paper mill in Hyltebruk. As acontrol site, I compared these with Rocknen nature reserve area.At each site I took 6 soil samples, representing the top 15-20 cm of soil and organic material.Samples were analysed with an Atomic Absorption Spectrometer and the concentrations oflead, copper and zinc were determined per ashed dry material.I analyzed the samples at the laboratory using the guideline from the Swedish StandardInstitute for water analysis.The concentrations of the soil samples showed no significant difference between the naturereserve area and the industrial sites (One-way ANOVA). This was due to very variableorganic content within and between the sites.Organic content of the samples has a significantly effect on the metal concentrations for Pband Cu (Linear Regression test). In conclusion, metals can accumulate in the vegetation, andin case of Pb and Cu there is a correlation between their concentration and the amount oforganic matter. Therefore in future studies it is best if soil with very high organic content orvegetation is used to determine if forest soil near industries are affected by past or presentindustrial emissions of heavy metals.
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Edwards, Sion Charles. "The behaviour of mercury and copper contamination in a lowland river system and their accumulation by some biota". Thesis, Imperial College London, 1995. http://hdl.handle.net/10044/1/7457.
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Malfaisan, Charles. "Accumulation du cuivre dans les plantes spontanée de vignoble". Electronic Thesis or Diss., Pau, 2024. http://www.theses.fr/2024PAUU3055.
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L'application de fongicides à base de cuivre pour lutter contre le mildiou dans les vignobles a entraîné une accumulation de cuivre dans les sols, en particulier dans les grandes régions viticoles telles que la Nouvelle-Aquitaine. Cette contamination pose des problèmes environnementaux majeurs, affectant la qualité des sols et la biodiversité. Bien que la réduction de l'utilisation de cuivre soit amorcée, son usage reste essentiel pour lutter contre les maladies fongiques des vignes, avec un risque d'impact sur les écosystèmes viticoles.Ce travail vise à analyser la biodisponibilité et la spéciation du cuivre dans deux sols viticoles de la région Nouvelle-Aquitaine (un sol alcalin et un sol acide) et à évaluer la réponse de deux espèces de plantes spontanées (Amaranthus retroflexus et Chenopodium album) aux niveaux de cuivre présents naturellement dans ces sols, ainsi qu'enrichis en laboratoire. L'hypothèse est que ces plantes peuvent développer des mécanismes de tolérance au cuivre, offrant des perspectives pour la gestion des sols contaminés.La spéciation et la biodisponibilité du cuivre dans les sols ont été étudiées à l'aide de méthodes d'extractions chimiques simples, d’électrochimie et de modélisations géochimiques. Une expérience en pots a ensuite été menée sur ces sols enrichis ou pas en cuivre, pour examiner les mécanismes d'accumulation du métal au sein des plantes. Ces données ont ensuite été comparées à l'accumulation des plantes ayant poussé naturellement sur site viticole.Les résultats ont montré que, dans des conditions contrôlées, les deux plantes ont mis en œuvre une stratégie d'exclusion du cuivre dans le sol alcalin, en accumulant le cuivre dans les racines, associé à une faible translocation vers les parties aériennes. En revanche, aucune croissance n’a été observée sur le sol acide, indiquant une toxicité excessive du cuivre dans ce contexte. La spectroscopie d'absorption des rayons X (XANES et EXAFS) et l'imagerie par microfluorescence X sur rayonnement synchrotron (µXRF) couplée au µXANES, ont montré que le cuivre s'accumulait dans les racines sous forme de complexes avec des ligands carboxyle et hydroxyle, principalement au niveau du rhizoderme.L' étude menée sur Amaranthus retroflexus ayant poussé en conditions réelles sur le sol alcalin a révélé des concentrations importantes de cuivre dans les feuilles, notamment au niveau de la cuticule, suggérant une pénétration foliaire du fongicide. La présence spontanée d'Amaranthus retroflexus pourrait ainsi constituer une surface tampon lors des traitements phytosanitaires, réduisant ainsi la contamination directe des sols par ces produits.Ces résultats ouvrent la voie à une meilleure compréhension du rôle écologique de ces plantes dans la gestion des sols contaminés. À l'avenir, leur potentiel pour limiter l'impact du cuivre sur les sols pourrait être exploité dans des stratégies de gestion durable des agroécosystèmes viticolesThe application of copper-based fungicides to fight downy mildew in vineyards has led to copper accumulation in soils, particularly in major wine-growing regions such as Nouvelle-Aquitaine. This contamination raises serious environmental concerns, affecting soil quality and biodiversity. Despite recent efforts to reduce copper use, its application remains essential to struggle against fungal diseases in vines, with potential impact on the ecosystems.This work aims to analyze copper bioavailability and speciation in two vineyard soils from the Nouvelle-Aquitaine region (one alkaline and one acidic) and to assess the response of two spontaneous plant species (Amaranthus retroflexus and Chenopodium album) to copper levels naturally present in the vineyard sites, as well as those enriched in the laboratory. The hypothesis is that these plants may develop copper tolerance mechanisms, offering potential alternatives for vineyard soil management.Copper speciation and bioavailability in these soils were studied using simple chemical extraction methods, electrochemical analyses, and geochemical modeling. A pot experiment was then conducted on these native and copper-enriched soils to examine the mechanisms of metal accumulation developed by the plants. These data were then compared to copper accumulation of plants naturally grown on the site.The results showed that, under controlled conditions, the two plants developed a copper exclusion strategy in the alkaline vineyard soil, accumulating copper in their roots and preventing its translocation to aerial parts. In contrast, no growth was observed in the acidic soil, indicating excessive copper toxicity. X-ray absorption spectroscopy (XANES and EXAFS) and synchrotron µ X-ray fluorescence (µXRF) imaging coupled with µXANES showed that copper was accumulated in the roots as complexes with carboxyl and hydroxyl ligands, mainly located at the rhizodermis level.The study of Amaranthus retroflexus grown on the alkaline vineyard revealed high concentrations of copper in the leaves, mainly in the cuticle, suggesting a foliar uptake of fungicides. The spontaneous presence of Amaranthus retroflexus could thus be used as a buffer surface during phytosanitary treatments, thereby reducing the direct contamination of soils by these products.These results pave the way for a better understanding of the ecological role of these plants in managing contaminated soils. In the future, their potential to limit the impact of copper on vineyard soils could be harnessed in sustainable management strategies for vineyard agroecosystems
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Schwertfeger, Dina. "The effects of soil leaching on metal bioavailability, toxicity and accumulation in Hordeum vulgare cultivated in copper amended soils". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115837.
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Discrepancies in ecotoxicity effects data derived from soils amended with dissolved metals in the laboratory and soils from historically aged metal-contaminated sites pose a challenge in deriving environmentally relevant soil quality criteria. In this thesis, the chemical artefacts produced by dissolved metal additions and the subsequent effects on metal bioavailability, toxicity and bioaccumulation are examined. The overall goal of this research is to advance the understanding of soil trace metal bioavailability mechanisms and improve current methods for ecotoxicity testing and bioavailability modeling.The first objective was to develop a leaching method which would minimize the "salt-effect" commonly observed in freshly-spiked soil samples. This was achieved by adapting a column leaching procedure in order to spike and leach larger volumes of test soil as a preparatory step prior to ecotoxicity assays. An experiment was set up to observe changes to leachate chemistry resulting from the dissolved Cu additions and subsequent leaching with two weak electrolyte solutions. Results showed that leaching removed the excess dissolved Cu as well as the excess acidity and base cations that were solubilized during the Cu additions. Differences between control and spiked samples of some key soil solution parameters (e.g. pH, DOC and total dissolved Ca, Mg, Al, Fe) were reduced thereby resulting in a set of spiked samples more conducive to deriving causal dose-response relationships.
A second experiment compared soil and soil solution properties of samples which underwent the spike/leach procedure to those of freshly spiked samples. Lower soil pH (up to 0.81 pH units) and DOC concentrations were observed in non-leached samples as well as up to 35-fold and 55-fold increases of dissolved Ca and Mg concentrations, typical of the salt-effect. It was estimated that the non-leached samples contained up to 100-fold greater Cu2+ and 50-fold greater Al3+ activities which, I hypothesized, could result in greater phytotoxicity of non-leached samples. Bioassays were conducted wherein Hordeum vulgare (barley) seedlings were exposed to the leached and non-leached Cu-spiked soil samples for 14 days. The leached samples were less toxic to barley and showed significant increases (up to 1.7-fold) in median inhibitory concentrations (i.e. IC50) for root elongation in two of the three test soils. The Cu2+ fraction was able to explain much of the variability in toxicity between leached and non-leached samples, as well as among the different test soils. One exception was the most acidic test soil for which plants in the leached samples showed up to 10-fold greater toxicity than plants in the non-leached samples, when exposed to similar Cu2+ activities. Soil speciation and bioaccumulation data for Cu, Al and Ca were used to deduce that Ca deficiency and possibly Al toxicity contributed to the toxicity observed in this sample set.
In a modeling exercise, the concepts of the terrestrial biotic ligand model (TBLM), which take into account ion competition at the soil solution/root interface, to describe toxic response in our samples. Results showed that the additive effects of Cu and Al toxicity estimated from the Cu-root ligand complex (Cu-BL+) and Al-root ligand complex (Al-BL2+ ) accounted for more of the variability in toxic response data than did the Cu2+ fraction or the Cu-BL+ fraction alone. The model however, could not account for the effects of the Cu-induced Ca deficiency in the most acidic test soil, thus highlighting one of the limitations of the TBLM. This thesis has contributed to the understanding of metal bioavailability mechanisms affected by soil spiking procedures and highlights the benefits of soil leaching in preparing soil samples for ecotoxicity assays which should improve trace metal risk assessment in the future.
Livros sobre o assunto "Copper accumulation"
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Bagatto, Giuseppe. Copper, cadmium, nickel, zinc, iron, magnesium, and manganese accumulation in crayfish populations near copper-nickel smelters at Sudbury, Ontario, Canada. [s.l: s.n.], 1987.
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Zia, Shaheen. A laboratory study of the relationship between levels of copper and nickel in water, and their uptake and accumulation by various body tissues in Cambarus bartoni (Fab.) (Decapoda: Crustacea). [s.l: s.n.], 1987.
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Bardeggia, Michael Aldo J. A laboratory study of the relationship between levels of copper and nickel mixtures in the diet, and their uptake and accumulation by various body tissues in Cambarus Bartoni (FAB.) (DECAPODA - CRUSTACEA). Sudbury, Ont: Laurentian University, Department of Biology, 1990.
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Solimano, Andres, e Diego Calderón Guajardo. The Copper Sector, Fiscal Rules, and Stabilization Funds in Chile. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198817369.003.0010.
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Historically Chile’s economy has been dominated by mineral products (mainly copper) as a source of exports and fiscal revenues. Copper prices and other commodity prices are often volatile. Since the 1980s the authorities have developed various mechanisms to cope with copper price shocks and dampen their effects on the business cycle. These mechanisms include a fiscal rule and a stabilization fund under a flexible exchange rate and an inflation-targeting regime. Apparently, this macro framework has been associated (causality is another matter) with reasonably good macro outcomes. However, this framework entails more discretion and less flexibility than often portrayed. (i) The mechanisms described include frequent revisions in the target fiscal surplus. (ii) Sovereign wealth funds, while defining rules for accumulating resources in good times, provide no rules for using them in bad times. (iii) They entail a possible bias towards over-accumulation of funds, with an ensuing opportunity cost.
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Pott, Edison Beno. Relative bioavailability of copper and molybdenum sources and effect of molybdenum on molybdenum and copper excretion and tissue accumulation in lambs. 1992.
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Trocello, Jean-Marc, e France Woimant. Disorders of Copper and Iron Metabolism. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199972135.003.0044.
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Both copper and iron are essential metals that have a critical function in a series of biochemical pathways. This chapter describes the disorders associated with genetic abnormalities in copper and iron metabolic pathways and their manifestations in adult patients. Mutations in the genes of the copper transporting P-type ATPases, ATP7A and ATP7B are associated with Wilson disease, Menkes disease, occipital horn syndrome and ATP7A-related distal motor neuropathy. Neurodegeneration with brain iron accumulation (NBIA) is a group of disorders characterized by excess iron deposition in globus pallidus, substantia nigra pars reticulata, striata and cerebellar dentate nuclei. Several genes associated with NBIA have been identified.
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Pantola, R. C. Intracellular Copper Accumulation and Biochemical Changes in Response to Cu Induced Oxidative Stress in Brassica Species. GRIN Verlag GmbH, 2016.
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Keshav, Satish, e Palak Trivedi. Genetic liver disease. Editado por Patrick Davey e David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0214.
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This chapter discusses three of the major inherited forms of liver disease (all autosomal recessive): hereditary haemochromatosis, Wilson’s disease, and alpha-1-antitrypsin deficiency. Hereditary haemochromatosis is characterized by excessive absorption of dietary iron, with a pathological increase in total body iron that accumulates in tissues and organs, disrupting their function. Wilson’s disease (hepatolenticular degeneration) is an autosomal recessive genetic disorder in which copper accumulates in tissues. Alpha-1-antitrypsin deficiency is characterized by reduced circulating levels of alpha-1-antitrypsin, a liver-derived protease inhibitor, and accumulation within the hepatocytes of the abnormal, poorly degraded protein; the consequent excessive activity of proteases such as elastase in pulmonary alveoli, unopposed by protease inhibitors, leads to emphysema, and the accumulation of alpha-1-antitrypsin in hepatocytes causes liver dysfunction.
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Lei, Peng, Scott Ayton e Ashley I. Bush. Metal-Protein Attenuating Compounds in Neurodegenerative Diseases. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780190233563.003.0015.
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Neurodegenerative disorders including Alzheimer’s (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS) are progressive diseases of the aging population with currently few therapeutic options. While aggregation and deposition of disease-specific proteins link the pathologies of these diseases, targeting these aggregating proteins with therapeutics has not yet been successful in clinical trial. This chapter profiles metals (copper, zinc, and iron) as alternative drug targets for neurodegeneration. Complex changes to metals occur in these neurodegenerative diseases. Accumulating evidences have demonstrated that perturbations to metal homeostasis contribute to the progression of neuronal dysfunction and death. Importantly, several phase II trials have shown that correcting metal dyshomeostasis improves clinical outcomes; the chapter argues that it is now time to explore the therapeutic utility of metal-based drugs in larger, phase III trials.
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Wilson’s Disease. Exon Publications, 2024. http://dx.doi.org/10.36255/wilsons-disease.
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Wilson’s Disease is a rare genetic disorder that disrupts the body’s ability to eliminate excess copper, leading to harmful accumulations in organs such as the liver, brain, and eyes. This article serves as a comprehensive guide, providing clear and detailed information for patients, families, and caregivers. It begins by explaining what Wilson’s Disease is and the role of the ATP7B gene in causing the condition. The article explores its prevalence, types, and inheritance patterns, highlighting the importance of genetic testing and family screening. The article discusses the wide range of symptoms, from liver damage and neurological issues to the characteristic Kayser-Fleischer rings in the eyes. It explains the diagnostic process, including blood tests, eye exams, and genetic analysis, which help confirm the condition. Treatment options such as chelation therapy with drugs like penicillamine (Cuprimine) or trientine (Syprine), zinc acetate (Galzin), and dietary changes are explored in depth. The article also addresses the prognosis and offers practical advice for living with Wilson’s Disease, emphasizing the importance of regular medical care and emotional support. Written in straightforward language, this book ensures that all readers can understand and apply the information to navigate life with Wilson’s Disease effectively.
Capítulos de livros sobre o assunto "Copper accumulation"
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Tinker, D., N. Romero e R. Rucker. "The Role of Copper and Cross-Linking in Elastin Accumulation". In Trace Elements in Man and Animals 6, 277–78. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0723-5_86.
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Chen, Yingxu, Mingge Yu e Dechao Duan. "Tolerance, Accumulation, and Detoxification Mechanism of Copper in Elsholtzia splendens". In Soil Biology, 317–44. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-21408-0_17.
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Moseley, Jeffrey, Jeanette Quinn, Mats Eriksson e Sabeeha Merchant. "Targets of Copper Responsive Gene Expression in Chlamydomonas are Required for PSI Accumulation in Copper-Deficient Cells of Chlamydomonas". In Photosynthesis: Mechanisms and Effects, 3221–26. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-3953-3_752.
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Hill, R., Margaret Leighton, Vivienne Heys e D. M. Jones. "The Accumulation of Copper, Zinc, Manganese and Iron in the Foetus of Deer". In Trace Elements in Man and Animals 6, 617–18. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0723-5_223.
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Chelomin, V. P., O. N. Lukjanova e E. A. Bobkova. "Effects of Temperature and Cadmium on the Accumulation of Copper by Mussel Tissues". In The GeoJournal Library, 287–96. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2773-8_22.
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McCormick, Charles C., e Lih-Y. Lin. "Accumulation of Hepatic Zn7 and Zn/Cu Metallothionein in Copper-Loaded Chicks: Isolation and Characterization". In Trace Elements in Man and Animals 6, 39–40. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0723-5_13.
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Grover, Z., P. Lewindon, A. Clousten, A. Shaag, O. Elpeleg e D. Coman. "Hepatic Copper Accumulation: A Novel Feature in Transient Infantile Liver Failure Due to TRMU Mutations?" In JIMD Reports, 109–13. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/8904_2014_402.
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Li, Yu, Yuji Togashi e Noritoshi Takeichi. "Abnormal Copper Accumulation in the Liver of LEC Rats: A Rat Form of Wilson’s Disease". In The LEC Rat, 122–32. Tokyo: Springer Japan, 1991. http://dx.doi.org/10.1007/978-4-431-68153-3_13.
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Srivastava, Jyoti, Joyabrata Mal, Manju Verma e Rupika Sinha. "Mini-review on Inhibitors of Human Tyrosinase". In Proceedings of the Conference BioSangam 2022: Emerging Trends in Biotechnology (BIOSANGAM 2022), 96–105. Dordrecht: Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-020-6_10.
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AbstractMelanin is a major pigment of human skin that protects the skin from harmful ultraviolet radiation, DNA damage and oxidative stress. However, the excess accumulation of melanin may lead to various hyperpigmentation-related diseases. Tyrosinase is a copper containing enzyme that regulates the rate-limiting step of melanin synthesis. So, inhibiting tyrosinase is the crucial target for researchers for the treatment of hyperpigmentation. Unfortunately, almost all the literature is based on mushroom tyrosinase (mTYR) for their application on humans as pure human tyrosinase (hTYR) is difficult to isolate. Since presently used tyrosinase inhibitors are developed using mushroom tyrosinase, they are insufficient to match the affinity, selectivity and efficacy required to target the human tyrosinase. Therefore, there is an urgent need for identifying a selective tyrosinase inhibitor that matches the selectivity and safety standards of human tyrosinase. This mini-review is focused on the tyrosinase inhibitors developed and evaluated using human tyrosinase.
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van Haren, R. J. F., J. van der Meer e M. B. de Vries. "Cadmium and copper accumulation in the common mussel Mytilus edulis in the Western Scheldt estuary: a model approach". In North Sea—Estuaries Interactions, 105–18. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2000-2_9.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Copper accumulation"
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Ellis, Peter F. "Pitting Corrosion in Domestic Copper Plumbing—the Rise and Fall of the “Pitting Water” Theory". In CORROSION 2000, 1–10. NACE International, 2000. https://doi.org/10.5006/c2000-00652.
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Abstract The theory that “pitting water”—nonaggressive water with high alkalinity and conductivity—is the primary cause of pitting of cold water copper domestic piping appeared in the literature in 1971. This theory gained popularity for a period of time. However, the accumulation of further evidence showed that the theory was non-predictive, and its original proponents retracted it in the 1980’s. Nonetheless, “pitting water” is blamed for pitting of copper domestic plumbing with disturbing frequency more than a decade after the original proponents of the theory withdrew it. A critical review of the literature is presented showing how the “pitting water” theory arose and tracing the accumulation of evidence that invalidates this theory. The case is presented that the concept of “pitting water” is not mechanistically significant, and that most, if not, all pitting of domestic copper plumbing attributed to “pitting water,” is in fact of anthropogenic (human-caused) origin.
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Drach, Andrew, Igor Tsukrov, Judson DeCew, Uwe Hofmann, Jochen Aufrecht e Adolf Grohbauer. "Corrosion and Biofouling Performance of Copper Alloys Investigated in the North Atlantic Ocean". In CORROSION 2013, 1–9. NACE International, 2013. https://doi.org/10.5006/c2013-02770.
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Abstract A field testing of corrosion and biofouling behavior of eight copper alloys was carried out at the Portsmouth Harbor, USA (North Atlantic Ocean). The plate specimens of the alloys were submerged for one year to investigate the effect of seawater exposure on corrosion and accumulation of biofouling. The specimens were divided into two sets to evaluate the effect of intermittent corrosion layer removal (three-month periods) vs. continuous exposure with undisrupted surface layer. Corrosion behavior was characterized as uniform corrosion rates through weight measurements, and as localized corrosion attack through analysis of cross-sections. Biofouling behavior was quantified in terms of the biomass accumulation. It was found that the corrosion rates of the specimens with intermittent removal of corrosion layer were approximately 2.4 times higher than those with intact surface. The biofouling resistance of eight alloys was found to be excellent: less than 0.5% of weight increase over the whole exposure period. However, one of the alloys demonstrated poor resistance (40% increase in weight).
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Alratoee, Abdullah M., Min Hyun Cho e Naif H. Abdulkareem. "Premature Failure of Copper Nickel Tubes Due to Microbiologically Influenced Corrosion (MIC) - a Case Study". In MECC 2023, 1–11. AMPP, 2023. https://doi.org/10.5006/mecc2023-20150.
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Abstract This paper highlights the importance of implementing a robust corrosion management program for copper-nickel tubes in seawater applications. Although these alloys are known for their natural resistance to seawater corrosion, failures can occur due to various factors such as inadequate corrosion management program and insufficient control of deposits accumulation and bacterial growth. The investigation discussed in this paper focuses on the premature Microbiologically Influenced Corrosion (MIC) failure of copper-nickel tubes in a Trim-cooler equipment that operated for only seven (7) months. The findings suggest that the causal factors of the failure were related to the accumulation of deposits and the growth of bacteria in the seawater, which compromised the protective surface film on the tubes and accelerated the corrosion process. To address this issue, the study recommends the implementation of an effective bacteria treatment and deposits filtration system to prevent the build-up of harmful materials in the seawater. This can be achieved through regular monitoring and cleaning of the equipment, as well as the use of adequate filtration and treatment technologies that are tailored to the specific needs of copper-nickel alloys in seawater applications. Overall, this paper emphasizes the importance of a proactive approach to corrosion management in seawater applications, particularly when using copper-nickel alloys. By implementing the right corrosion control measures, it is possible to extend the service life of equipment, minimize downtime and maintenance costs, and ensure safe and reliable operations in harsh marine environments.
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Caldwell, Madison, Sarah Evans e Brian Lockamon. "Development of a Solvent to Maintain Steam Generator Deposit Inventories within Acceptable Levels". In CORROSION 2006, 1–5. NACE International, 2006. https://doi.org/10.5006/c2006-06537.
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Abstract The input rate for deposits in steam generators (SGs) is an important concern for utilities, since deposit buildup can impact heat transfer as well as cause significant damage to tubes and other critical SG components. For a typical plant, every 1 ppb of iron in feedwater results in one third of a pound of deposits per day accumulating in the steam generators. Startup activities have been shown to contribute over 100 pounds to the steam generator deposit inventory. There are a number of factors that attribute to the accumulation of deposits, some of which can be mitigated with secondary chemistry operations and balance-of-plant maintenance and replacement. However, some amount of iron and/or copper will continue to be transported into the SGs during operations, especially during transients in power. While there are various mechanical methods for removing deposit buildup in the SGs (e.g., upper bundle flush and sludge lancing), mechanical methods are not always effective in targeting the critical inventory locations. Deposit buildup and corrosion as a result of the sludge accumulation will typically require a more aggressive removal technique (e.g., chemical cleaning) or a significantly greater economic decision to replace the SGs. The need for inexpensive, non-critical path methods to periodically remove accumulated corrosion products from SGs has been identified for several years. In response to this need, a low-concentration removal solvent that can be applied during or after cooldown to remove a large portion of the accumulated deposits from the previous cycle(s) and minimize the total sludge inventory is currently under development. The solvent is a relatively simple, single solution that can dissolve both iron and copper deposits from SGs. This treatment can be applied every 2-3 cycles, avoiding full scale chemical cleanings, with minimal corrosion.
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Pilecka-Ulcugaceva, Jovita, Anda Bakute, Maris Bertins, Kristaps Siltumens e Inga Grinfelde. "ASSESSMENT OF HEAVY METAL CONTAMINATION IN URBAN SNOW: A CASE STUDY OF NICKEL AND COPPER IN JELGAVA, LATVIA". In 24th SGEM International Multidisciplinary Scientific GeoConference 2024, 177–84. STEF92 Technology, 2024. https://doi.org/10.5593/sgem2024v/4.2/s18.25.
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Snow water pollution, especially from heavy metals, is a growing global environmental concern, as urbanization and industrial activities increasingly contribute to the contamination of precipitation. Snow, acting as a natural filter, accumulates atmospheric pollutants, which are subsequently released during snowmelt, entering stormwater systems and surface water bodies. This issue has been observed across Europe, North America, and other industrialized regions, where heavy metals such as nickel (Ni) and copper (Cu) are prevalent contaminants. In Latvia, studies on snow pollution remain limited, making it crucial to understand how urbanization impacts snow water quality, particularly in cities like Jelgava. This study, conducted during the winters of 2023 and 2024, focuses on the accumulation of heavy metals in snow samples from Jelgava city. A total of 177 snow samples were collected each year from various urban locations, alongside 3 samples from outside the city as controls. The aim is to identify areas with the highest pollution levels and assess their potential contribution to stormwater pollution. The results revealed that nickel concentrations in the urban snow samples had an average of 0.124 mg/L, with values ranging from 0.033 mg/L to a maximum of 0.393 mg/L. Copper concentrations, however, showed greater variability, with an average of 0.906 mg/L, a minimum of 0.000 mg/L, and a maximum of 4.427 mg/L. Pollution areas were identified using Arc GIS and using the IDW method. These findings indicate that urban snowmelt in Jelgava could be a significant source of heavy metal pollution, particularly copper, to the city's drainage systems and natural water bodies.
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Marks, Chuck, Michael J. Little, Marc A. Kreider e Robert D. Varrin. "Benefits of Partial Removal of Corrosion Deposits from Nuclear Steam Generators: ASCA and CODE Applications". In CORROSION 2017, 1–15. NACE International, 2017. https://doi.org/10.5006/c2017-09481.
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Abstract As with many heat exchangers, nuclear steam generators are subject to the accumulation of corrosion product deposits on heated tube surfaces and other internal components on the secondary (shell) side. These deposits can have adverse effects on thermal efficiency, material integrity, and in some cases plant operability. Accordingly, plant operators routinely devote substantial resources to limiting the generation and accumulation of deposits, including periodic removal of deposits through various mechanical and chemical approaches. Since the 1980s, chemical cleaning processes with solvents designed to remove all (or nearly all) of the iron- and copper-based deposit material from the steam generator (SG) secondary side have been employed in dozens of different units worldwide. Although these full-bundle “hard” chemical cleaning processes have generally been quite successful in removing large fractions of the deposit mass (typically >95%), they are complex, costly evolutions that require additional plant downtime. Additionally, a few units have unexpectedly experienced declines in SG heat-transfer efficiency and plant production following a successful cleaning application due to the removal of thermally beneficial scale layers. During the past 15 years, alternative processes designed to periodically remove only a fraction of the secondary SG deposit inventory have been developed and qualified by the authors. One of these is an advanced scale conditioning agent (ASCA) treatment, a dilute or “soft” chemical cleaning method that focuses on penetrating through consolidated tube scale layers. By removing a fraction of the iron-based matrix material throughout the scale layer thickness—but without fully removing the layer—ASCA applications increase the average scale porosity and thereby improve the associated scale thermal properties, raising SG thermal performance levels. ASCA processes have three principal benefits: 1) immediate, reliable improvements in SG heat-transfer efficiency as demonstrated by analysis of more than a dozen field applications, 2) reduction in the long-term rate of deposit accumulation within the SG (lowering long-term risks of component corrosion and heat-transfer fouling), and 3) substantially reduced application complexity and cost, including no added plant downtime. A second type of process developed by the authors, consolidated deposit extraction (CODE) removal, focuses on the dissolution of non-iron binding species such as oxides of aluminum and silicon from the deposits that form at the lower SG tubesheet elevation in vertically oriented SGs. These deposits typically are very hard and non-porous, making them at least partially resistant to removal through conventional chemical and mechanical removal methods. Laboratory test results and one successful plant application indicate that the use of CODE in conjunction with other cleaning methods can increase the cleaning yield for these hardened, consolidated deposits.
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Wagner, Patricia, Louis Janus e Brenda Little. "An Evaluation of Surface Treatments for Copper-Nickel Seawater Systems". In CORROSION 1988, 1–12. NACE International, 1988. https://doi.org/10.5006/c1988-88399.
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Abstract Corrosion in 90/10 Cu-Ni pipes was evaluated using estuarine water from the Gulf of Mexico at the mouth of the Pascagoula River, maintained at a flow rate of 3 to 6 ft/sec over a 1-year period. The impact of surface preparation, batch FeSO4 (50 ppb Fe+2 for 48 hours) pretreatment, and intermittent treatment was evaluated. Surface deposits were characterized by scanning electron microscopy and energy-dispersive x-ray fluorescence spectrometry. Water analyses included pH, dissolved oxygen, dissolved sulfide and sulfate, total organic carbon, total suspended solids and dissolved heavy metal analyses, as well as quantification of bacteriological components. Batch FeSO4 treatment did not result in a persistent increase in surface-bound iron and or decreased localized corrosion. Surface pitting appeared to be associated with accumulations of chlorine, sulfur and microbiological colonization.
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Zhelezny, Vitaly, Yaroslav Grosu, Yana Hlek, Bohdan Kvasnytskyi, Viacheslav Khalak e Dmytro Ivchenko. "Sedimentation Stability and Caloric Properties of Nanohybrid Composite Thermo-Accumulating Material Paraffin/Thermally Expanded Graphite/Copper Oxide Nanoparticles". In 2024 IEEE 14th International Conference Nanomaterials: Applications & Properties (NAP), 1–4. IEEE, 2024. http://dx.doi.org/10.1109/nap62956.2024.10739701.
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Katsanis, E. P., W. B. Esmonde e R. W. Spencer. "Soluble Silicates as Corrosion Inhibitors in Water Systems". In CORROSION 1985, 1–15. NACE International, 1985. https://doi.org/10.5006/c1985-85369.
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Abstract Sodium silicates, used alone or in combination with other chemical inhibitors, are a safe and reliable means of protecting water pipes from corrosion. Silicates have been used successfully to inhibit corrosion in water systems in homes and large buildings and in municipal and industrial water distribution systems. The silicates protect pipes by creating a thin protective film on pipe surfaces. In some cases, the silicates have also displaced or removed rust accumulations. Silicate treatment has proven equally effective with ferrous metals, lead, copper and alloys including brass. They also protect aluminum and other soft metals and alloys. This paper discusses the chemistry, conditions for use, time and aging effects and recommended dosage treatments for sodium silicate as a corrosion inhibitor. Sodium silicate is one of three treatments recommended in a report on corrosion contracted by the US Environmental Protection Agency. Some writers recommend silicates over other inhibitors when economic, toxicity and environmental factors are taken into consideration. Sodium silicate is low in cost and does not contribute to algal growth or to the eutrophication of fresh waters.
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Pruteanu, Augustina, Iulian Voicea e Viorel Fatu. "Accumulation of copper in vegetables and fruits". In 21st International Scientific Conference Engineering for Rural Development. Latvia University of Life Sciences and Technologies, Faculty of Engineering, 2022. http://dx.doi.org/10.22616/erdev.2022.21.tf191.
Texto completo da fonteRelatórios de organizações sobre o assunto "Copper accumulation"
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Zinkle, S. J., L. L. Snead e D. J. Edwards. Comparison of defect cluster accumulation and pattern formation in irradiated copper and nickel. Office of Scientific and Technical Information (OSTI), abril de 1995. http://dx.doi.org/10.2172/114927.
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Prusky, Dov, Nancy P. Keller e Amir Sherman. global regulation of mycotoxin accumulation during pathogenicity of Penicillium expansum in postharvest fruits. United States Department of Agriculture, janeiro de 2014. http://dx.doi.org/10.32747/2014.7600012.bard.
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Background to the topic- Penicilliumas a postharvest pathogen and producer of the mycotoxin PAT. Penicilliumspp. are destructive phytopathogens, capable of causing decay in many deciduous fruits, during postharvest handling and storage; and the resulting losses can amount to 10% of the stored produce and the accumulation of large amounts of the mycotoxinpatulin. The overall goal of this proposal is to identify critical host and pathogen factors that modulate P. expansummycotoxin genes and pathways which are required for PAT production and virulence. Our preliminary results indicated that gluconic acid are strongly affecting patulin accumulation during colonization. P. expansumacidifies apple fruit tissue during colonization in part through secretion of gluconic acid (GLA). Several publications suggested that GLA accumulation is an essential factor in P. expansumpathogenicity. Furthermore, down regulation of GOX2 significantly reduced PAT accumulation and pathogenicity. PAT is a polyketide and its biosynthesis pathway includes a 15-gene cluster. LaeA is a global regulator of mycotoxin synthesis. It is now known that patulin synthesis might be subjected to LaeA and sometimes by environmental sensing global regulatory factors including the carbon catabolite repressor CreA as well as the pH regulator factor PacC and nitrogen regulator AreA. The mechanisms by which LaeA regulates patulin synthesis was not fully known and was part of our work. Furthermore, the regulatory system that controls gene expression in accordance with ambient pH was also included in our work. PacC protein is in an inactive conformation and is unable to bind to the promoter sites of the target genes; however, under alkaline growth conditions activated PacC acts as both an activator of alkaline-expressed genes and a repressor of acid-expressed genes. The aims of the project- This project aims to provide new insights on the roles of LaeA and PacC and their signaling pathways that lead to GLA and PAT biosynthesis and pathogenicity on the host. Specifically, our specific aims were: i) To elucidate the mechanism of pH-controlled regulation of GLA and PAT, and their contribution to pathogenesis of P. expansum. We are interested to understanding how pH and/or GLA impact/s under PacC regulation affect PAT production and pathogenesis. ii) To characterize the role of LaeA, the global regulator of mycotoxin production, and its effect on PAT and PacC activity. iii) To identify the signaling pathways leading to GLA and PAT synthesis. Using state- of-the-art RNAseq technologies, we will interrogate the transcriptomes of laeAand pacCmutants, to identify the common signaling pathways regulating synthesis of both GLA and PAT. Major conclusions, solutions, achievements- In our first Aim our results demonstrated that ammonia secreted at the leading edge of the fungal colony induced transcript activation of the global pH modulator PacC and PAT accumulation in the presence of GLA. We assessed these parameters by: (i) direct exogenous treatment of P. expansumgrowing on solid medium; (ii) direct exogenous treatment on colonized apple tissue; (iii) growth under self-ammonia production conditions with limited carbon; and (iv) analysis of the transcriptional response to ammonia of the PAT biosynthesis cluster. Ammonia induced PAT accumulation concurrently with the transcript activation of pacCand PAT biosynthesis cluster genes, indicating the regulatory effect of ammonia on pacCtranscript expression under acidic conditions. Transcriptomic analysis of pH regulated processes showed that important genes and BARD Report - Project 4773 Page 2 of 10 functionalities of P. expansumwere controlled by environmental pH. The differential expression patterns of genes belonging to the same gene family suggest that genes were selectively activated according to their optimal environmental conditions to enable the fungus to cope with varying conditions and to make optimal use of available enzymes. Concerning the second and third Aims, we demonstrated that LaeA regulates several secondary metabolite genes, including the PAT gene cluster and concomitant PAT synthesis invitro. Virulence studies of ΔlaeAmutants of two geographically distant P. expansumisolates (Pe-21 from Israel and Pe-T01 from China) showed differential reduction in disease severity in freshly harvested fruit ranging from no reduction for Ch-Pe-T01 strains in immature fruit to 15–25% reduction for both strains in mature fruit, with the ΔlaeAstrains of Is-Pe-21 always showing a greater loss in virulence. Results suggest the importance of LaeA regulation of PAT and other secondary metabolites on pathogenicity. Our work also characterized for the first time the role of sucrose, a key nutritional factor present in apple fruit, as a negative regulator of laeAexpression and consequent PAT production in vitro. This is the first report of sugar regulation of laeAexpression, suggesting that its expression may be subject to catabolite repression by CreA. Some, but not all of the 54 secondary metabolite backbone genes in the P. expansumgenome, including the PAT polyketide backbone gene, were found to be regulated by LaeA. Together, these findings enable for the first time a straight analysis of a host factor that potentially activates laeAand subsequent PAT synthesis.
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Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova e Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, janeiro de 2016. http://dx.doi.org/10.32747/2016.7604286.bard.
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The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.
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Steffens, John C., e Eithan Harel. Polyphenol Oxidases- Expression, Assembly and Function. United States Department of Agriculture, janeiro de 1995. http://dx.doi.org/10.32747/1995.7571358.bard.
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Polyphenol oxidases (PPOs) participate in the preparation of many plant products on the one hand and cause considerable losses during processing of plant products on the other hand. However, the physiological functions of plant PPO were still a subject of controversy at the onset of the project. Preliminary observations that suggested involvement of PPOs in resistance to herbivores and pathogens held great promise for application in agriculture but required elucidation of PPO's function if modulation of PPO expression is to be considered for improving plant protection or storage and processing of plant products. Suggestions on a possible role of PPO in various aspects of chloroplast metabolism were also relevant in this context. The characterization of plant PPO genes opened a way for achieving these goals. We reasoned that "understanding PPO targeting and routing, designing ways to manipulate its expression and assessing the effects of such modifications will enable determination of the true properties of the enzyme and open the way for controlling its activity". The objective of the project was to "obtain an insight into the function and biological significance of PPOs" by examining possible function(s) of PPO in photosynthesis and plant-pest interactions using transgenic tomato plants; extending our understanding of PPO routing and assembly and the mechanism of its thylakoid translocation; preparing recombinant PPOs for use in import studies, determination of the genuine properties of PPOs and understanding its assembly and determining the effect of PPO's absence on chloroplast performance. Results obtained during work on the project made it necessary to abandon some minor objectives and devote the effort to more promising topics. Such changes are mentioned in the 'Body of the report' which is arranged according to the objectives of the original proposal. The complex expression pattern of tomato PPO gene family was determined. Individual members of the family are differentially expressed in various parts of the plant and subjected to developmentally regulated turnover. Some members are differentially regulated also by pathogens, wounding and chemical wound signals. Wounding systemically induces PPO activity and level in potato. Only tissues that are developmentally competent to express PPO are capable of responding to the systemic wounding signal by increased accumulation of PPO mRNA. Down regulation of PPO genes causes hyper susceptibility to leaf pathogens in tomato while over expression regulation of PPO expression in tomato plants is their apparent increased tolerance to drought. Both the enhanced disease resistance conferred by PPO over expression and the increased stress tolerance due to down regulation can be used in the engineering of improved crop plants. Photosynthesis rate and variable fluorescence measurements in wild type, and PPO-null and over expressing transgenic tomato lines suggest that PPO does not enable plants to cope better with stressful high light intensities or reactive oxygen species. Rather high levels of the enzyme aggravate the damage caused under such conditions. Our work suggests that PPO's primary role is in defending plants against pathogens and herbivores. Jasmonate and ethylene, and apparently also salicylate, signals involved in responses to wounding and defense against herbivores and pathogens, enhance markedly and specifically the competence of chloroplasts to import and process pPPO. The interaction of the precursor with thylakoid membranes is primarily affected. The routing of PPO shows other unusual properties: stromal processing occurs in two sites, resulting in intermediates that are translocated across thylakoids by two different mechanisms - a DpH- and a Sec-dependent one. It is suggested that the dual pattern of processing and routing constitutes a'fail safe' mechanism, reflecting the need for a rapid and flexible response to defense challenges. Many of the observations described above should be taken into consideration when manipulation of PPO expression is contemplated for use in crop improvement.
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Miller, Gad, e Jeffrey F. Harper. Pollen fertility and the role of ROS and Ca signaling in heat stress tolerance. United States Department of Agriculture, janeiro de 2013. http://dx.doi.org/10.32747/2013.7598150.bard.
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The long-term goal of this research is to understand how pollen cope with stress, and identify genes that can be manipulated in crop plants to improve reproductive success during heat stress. The specific aims were to: 1) Compare heat stress dependent changes in gene expression between wild type pollen, and mutants in which pollen are heat sensitive (cngc16) or heat tolerant (apx2-1). 2) Compare cngc16 and apx2 mutants for differences in heat-stress triggered changes in ROS, cNMP, and Ca²⁺ transients. 3) Expand a mutant screen for pollen with increased or decreased thermo-tolerance. These aims were designed to provide novel and fundamental advances to our understanding of stress tolerance in pollen reproductive development, and enable research aimed at improving crop plants to be more productive under conditions of heat stress. Background: Each year crop yields are severely impacted by a variety of stress conditions, including heat, cold, drought, hypoxia, and salt. Reproductive development in flowering plants is highly sensitive to hot or cold temperatures, with even a single hot day or cold night sometimes being fatal to reproductive success. In many plants, pollen tube development and fertilization is often the weakest link. Current speculation about global climate change is that most agricultural regions will experience more extreme environmental fluctuations. With the human food supply largely dependent on seeds, it is critical that we consider ways to improve stress tolerance during fertilization. The heat stress response (HSR) has been intensively studied in vegetative tissues, but is poorly understood during reproductive development. A general paradigm is that HS is accompanied by increased production of reactive oxygen species (ROS) and induction of ROS-scavenging enzymes to protect cells from excess oxidative damage. The activation of the HSR has been linked to cytosolic Ca²⁺ signals, and transcriptional and translational responses, including the increased expression of heat shock proteins (HSPs) and antioxidative pathways. The focus of the proposed research was on two mutations, which have been discovered in a collaboration between the Harper and Miller labs, that either increase or decrease reproductive stress tolerance in a model plant, Arabidopsis thaliana (i.e., cngc16--cyclic nucleotide gated channel 16, apx2-1--ascorbate peroxidase 2,). Major conclusions, solutions, achievements. Using RNA-seq technology, the expression profiles of cngc16 and apx2 pollen grains were independently compared to wild type under favourable conditions and following HS. In comparison to a wild type HSR, there were 2,776 differences in the transcriptome response in cngc16 pollen, consistent with a model in which this heat-sensitive mutant fails to enact or maintain a normal wild-type HSR. In a comparison with apx2 pollen, there were 900 differences in the HSR. Some portion of these 900 differences might contribute to an improved HSR in apx2 pollen. Twenty-seven and 42 transcription factor changes, in cngc16 and apx2-1, respectively, were identified that could provide unique contributions to a pollen HSR. While we found that the functional HS-dependent reprogramming of the pollen transcriptome requires specific activity of CNGC16, we identified in apx2 specific activation of flavonol-biosynthesis pathway and auxin signalling that support a role in pollen thermotolerance. Results from this study have identified metabolic pathways and candidate genes of potential use in improving HS tolerance in pollen. Additionally, we developed new FACS-based methodology that can quantify the stress response for individual pollen in a high-throughput fashion. This technology is being adapted for biological screening of crop plant’s pollen to identify novel thermotolerance traits. Implications, both scientific and agricultural. This study has provided a reference data on the pollen HSR from a model plant, and supports a model that the HSR in pollen has many differences compared to vegetative cells. This provides an important foundation for understanding and improving the pollen HSR, and therefor contributes to the long-term goal of improving productivity in crop plants subjected to temperature stress conditions. A specific hypothesis that has emerged from this study is that pollen thermotolerance can be improved by increasing flavonol accumulation before or during a stress response. Efforts to test this hypothesis have been initiated, and if successful have the potential for application with major seed crops such as maize and rice.