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Georges Calas - One of the best experts on this subject based on the ideXlab platform.
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Evidence for nanocrystals of vorlanite, a rare uranate mineral, in the Nopal I low-temperature uranium deposit (Sierra Peña Blanca, Mexico)
American Mineralogist, 2013Co-Authors: Guillaume Othmane, Thierry Allard, Nicolas Menguy, Guillaume Morin, Imène Esteve, Mostafa Fayek, Georges CalasAbstract:The occurrence of vorlanite, cubic CaUO4, is reported in the Nopal I uranium deposit (Sierra Pena Blanca, Mexico). This is the first time this rare calcium uranate has been found displaying a cubic morphology, in agreement with its crystal structure. Vorlanite occurs as nanoscale crystals embedded in U-bearing opal, with a Ca/U ratio of ∼1. Association with opal suggests that vorlanite formed at Nopal during late-stage U-mobilization under oxidizing conditions and low (
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evidence for nanocrystals of vorlanite a rare uranate mineral in the Nopal i low temperature uranium deposit sierra pena blanca mexico
American Mineralogist, 2013Co-Authors: Guillaume Othmane, Thierry Allard, Nicolas Menguy, Guillaume Morin, Imène Esteve, Mostafa Fayek, Georges CalasAbstract:The occurrence of vorlanite, cubic CaUO4, is reported in the Nopal I uranium deposit (Sierra Pena Blanca, Mexico). This is the first time this rare calcium uranate has been found displaying a cubic morphology, in agreement with its crystal structure. Vorlanite occurs as nanoscale crystals embedded in U-bearing opal, with a Ca/U ratio of ∼1. Association with opal suggests that vorlanite formed at Nopal during late-stage U-mobilization under oxidizing conditions and low (<50 °C) temperature. The presence of nanoscale uranate crystals in an environment largely dominated by uranyl silicates indicates that uranates may play a role in uranium scavenging at low temperature. In addition, the occurrence of vorlanite in the crystal shape consistent with its structure provides unique information on its conditions of formation.
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alteration geochemistry of the Nopal i uranium deposit sierra pena blanca mexico a natural analogue for a radioactive waste repository in volcanic tuffs
Terra Nova, 2008Co-Authors: Georges Calas, Thierry Allard, Pierre Agrinier, Philippe IldefonseAbstract:Natural analogues provide an approach to characterize and test the long-term modelling of a repository performance. This article presents geochemical information about the alteration conditions of the Nopal I uranium deposit, Mexico, an analogue for the proposed Yucca Mountain radioactive waste repository. Mineralization and hydrothermal alteration of volcanic tuffs are contemporaneous, according to petrographic observations. Trace element geochemistry (U, Th, REE) provides evidence for local mobilization of uranium under oxidizing conditions and further precipitation under reducing conditions. O- and H-isotope geochemistry of kaolinite, smectite, opal and calcite suggests that argillic alteration proceeded at shallow depth with meteoric water at 25–75 °C, a low-temperature context, unusual for volcanic-hosted uranium deposits. This temperature range is compatible with some post-closure evolution models of the proposed Yucca Mountain repository.
Thierry Allard - One of the best experts on this subject based on the ideXlab platform.
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Evidence for nanocrystals of vorlanite, a rare uranate mineral, in the Nopal I low-temperature uranium deposit (Sierra Peña Blanca, Mexico)
American Mineralogist, 2013Co-Authors: Guillaume Othmane, Thierry Allard, Nicolas Menguy, Guillaume Morin, Imène Esteve, Mostafa Fayek, Georges CalasAbstract:The occurrence of vorlanite, cubic CaUO4, is reported in the Nopal I uranium deposit (Sierra Pena Blanca, Mexico). This is the first time this rare calcium uranate has been found displaying a cubic morphology, in agreement with its crystal structure. Vorlanite occurs as nanoscale crystals embedded in U-bearing opal, with a Ca/U ratio of ∼1. Association with opal suggests that vorlanite formed at Nopal during late-stage U-mobilization under oxidizing conditions and low (
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evidence for nanocrystals of vorlanite a rare uranate mineral in the Nopal i low temperature uranium deposit sierra pena blanca mexico
American Mineralogist, 2013Co-Authors: Guillaume Othmane, Thierry Allard, Nicolas Menguy, Guillaume Morin, Imène Esteve, Mostafa Fayek, Georges CalasAbstract:The occurrence of vorlanite, cubic CaUO4, is reported in the Nopal I uranium deposit (Sierra Pena Blanca, Mexico). This is the first time this rare calcium uranate has been found displaying a cubic morphology, in agreement with its crystal structure. Vorlanite occurs as nanoscale crystals embedded in U-bearing opal, with a Ca/U ratio of ∼1. Association with opal suggests that vorlanite formed at Nopal during late-stage U-mobilization under oxidizing conditions and low (<50 °C) temperature. The presence of nanoscale uranate crystals in an environment largely dominated by uranyl silicates indicates that uranates may play a role in uranium scavenging at low temperature. In addition, the occurrence of vorlanite in the crystal shape consistent with its structure provides unique information on its conditions of formation.
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alteration geochemistry of the Nopal i uranium deposit sierra pena blanca mexico a natural analogue for a radioactive waste repository in volcanic tuffs
Terra Nova, 2008Co-Authors: Georges Calas, Thierry Allard, Pierre Agrinier, Philippe IldefonseAbstract:Natural analogues provide an approach to characterize and test the long-term modelling of a repository performance. This article presents geochemical information about the alteration conditions of the Nopal I uranium deposit, Mexico, an analogue for the proposed Yucca Mountain radioactive waste repository. Mineralization and hydrothermal alteration of volcanic tuffs are contemporaneous, according to petrographic observations. Trace element geochemistry (U, Th, REE) provides evidence for local mobilization of uranium under oxidizing conditions and further precipitation under reducing conditions. O- and H-isotope geochemistry of kaolinite, smectite, opal and calcite suggests that argillic alteration proceeded at shallow depth with meteoric water at 25–75 °C, a low-temperature context, unusual for volcanic-hosted uranium deposits. This temperature range is compatible with some post-closure evolution models of the proposed Yucca Mountain repository.
Nimbe Torres - One of the best experts on this subject based on the ideXlab platform.
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Nopal opuntia ficus indica protects from metabolic endotoxemia by modifying gut microbiota in obese rats fed high fat sucrose diet
Scientific Reports, 2017Co-Authors: Monica Sancheztapia, Edgar Pichardoontiveros, Armando R Tovar, Miriam Aguilarlopez, Claudia Perezcruz, Mei Wang, Sharon M Donovan, Nimbe TorresAbstract:Current efforts are directed to reducing the gut dysbiosis and inflammation produced by obesity. The purpose of this study was to investigate whether consuming Nopal, a vegetable rich in dietary fibre, vitamin C, and polyphenols can reduce the metabolic consequences of obesity by modifying the gut microbiota and preventing metabolic endotoxemia in rats fed a high fat and sucrose diet. With this aim, rats were fed a high fat diet with 5% sucrose in the drinking water (HFS) for 7 months and then were fed for 1 month with HFS + 5% Nopal (HFS + N). The composition of gut microbiota was assessed by sequencing the 16S rRNA gene. Nopal modified gut microbiota and increased intestinal occludin-1 in the HFS + N group. This was associated with a decrease in metabolic endotoxemia, glucose insulinotropic peptide, glucose intolerance, lipogenesis, and metabolic inflexibility. These changes were accompanied by reduced hepatic steatosis and oxidative stress in adipose tissue and brain, and improved cognitive function, associated with an increase in B. fragilis. This study supports the use of Nopal as a functional food and prebiotic for its ability to modify gut microbiota and to reduce metabolic endotoxemia and other obesity-related biochemical abnormalities.
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Nopal feeding reduces adiposity intestinal inflammation and shifts the cecal microbiota and metabolism in high fat fed rats
PLOS ONE, 2017Co-Authors: Sofia Moranramos, Armando R Tovar, Nimbe Torres, Xuan He, Elizabeth L Chin, Carolyn M Slupsky, Helen E RaybouldAbstract:Nopal is a cactus plant widely consumed in Mexico that has been used in traditional medicine to aid in the treatment of type-2 diabetes. We previously showed that chronic consumption of dehydrated Nopal ameliorated hepatic steatosis in obese (fa/fa) rats; however, description of the effects on other tissues is sparse. The aim of the present study was to investigate the effects of Nopal cladode consumption on intestinal physiology, microbial community structure, adipose tissue, and serum biochemistry in diet-induced obese rats. Rats were fed either a normal fat (NF) diet or a HF diet containing 4% of dietary fiber from either Nopal or cellulose for 6 weeks. Consumption of Nopal counteracted HF-induced adiposity and adipocyte hypertrophy, and induced profound changes in intestinal physiology. Nopal consumption reduced biomarkers of intestinal inflammation (mRNA expression of IL-6) and oxidative stress (ROS), modfied gut microbiota composition, increasing microbial diversity and cecal fermentation (SCFA), and altered the serum metabolome. Interestingly, metabolomic analysis of dehydrated Nopal revealed a high choline content, which appeared to generate high levels of serum betaine, that correlated negatively with hepatic triglyceride (TAG) levels. A parallel decrease in some of the taxa associated with the production of trimethylamine, suggest an increase in choline absorption and bioavailability with transformation to betaine. The latter may partially explain the previously observed effect of Nopal on the development of hepatic steatosis. In conclusion, this study provides new evidence on the effects of Nopal consumption on normal and HF-diet induced changes in the intestine, the liver and systemic metabolism.
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the effect of Nopal opuntia ficus indica on postprandial blood glucose incretins and antioxidant activity in mexican patients with type 2 diabetes after consumption of two different composition breakfasts
Journal of the Academy of Nutrition and Dietetics, 2014Co-Authors: Patricia Lopezromero, Edgar Pichardoontiveros, Azalia Avilanava, Natalia Vazquezmanjarrez, Armando R Tovar, Jose Pedrazachaverri, Nimbe TorresAbstract:Abstract Nopal is a plant used in traditional Mexican medicine to treat diabetes. However, there is insufficient scientific evidence to demonstrate whether Nopal can regulate postprandial glucose. The purpose for conducting this study was to evaluate the glycemic index, insulinemic index, glucose-dependent insulinotropic peptide (GIP) index, and the glucagon-like peptide 1 (GLP-1) index, and the effect of Nopal on patients with type 2 diabetes after consumption of a high-carbohydrate breakfast (HCB) or high-soy-protein breakfast (HSPB) on the postprandial response of glucose, insulin, GIP, GLP-1, and antioxidant activity. In study 1, the glycemic index, insulinemic index, GIP index, and GLP-1 index were calculated for seven healthy participants who consumed 50 g of available carbohydrates from glucose or dehydrated Nopal. In study 2, 14 patients with type 2 diabetes consumed Nopal in HCB or HSPB with or without 300 g steamed Nopal. The glycemic index of Nopal was 32.5±4, insulinemic index was 36.1±6, GIP index was 6.5±3.0, and GLP-1 index was 25.9±18. For those patients with type 2 diabetes who consumed the HCB+Nopal, there was significantly lower area under the curve for glucose (287±30) than for those who consumed the HCB only (443±49), and lower incremental area under the curve for insulin (5,952±833 vs 7,313±1,090), and those patients with type 2 diabetes who consumed the HSPB avoided postprandial blood glucose peaks. Consumption of the HSPB+Nopal significantly reduced the postprandial peaks of GIP concentration at 30 and 45 minutes and increased the antioxidant activity after 2 hours measured by the 2,2-diphenyl-1-picrilhidracyl method. These findings suggest that Nopal could reduce postprandial blood glucose, serum insulin, and plasma GIP peaks, as well as increase antioxidant activity in healthy people and patients with type 2 diabetes.
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opuntia ficus indica Nopal attenuates hepatic steatosis and oxidative stress in obese zucker fa fa rats
Journal of Nutrition, 2012Co-Authors: Sofia Moranramos, Patricia Lopezromero, Azalia Avilanava, Armando R Tovar, Jose Pedrazachaverri, Nimbe TorresAbstract:: Nonalcoholic fatty liver disease (NAFLD) is associated with multiple factors such as obesity, insulin resistance, and oxidative stress. Nopal, a cactus plant widely consumed in the Mexican diet, is considered a functional food because of its antioxidant activity and ability to improve biomarkers of metabolic syndrome. The aim of this study was to assess the effect of Nopal consumption on the development of hepatic steatosis and hepatic oxidative stress and on the regulation of genes involved in hepatic lipid metabolism. Obese Zucker (fa/fa) rats were fed a control diet or a diet containing 4% Nopal for 7 wk. Rats fed the Nopal-containing diet had ∼50% lower hepatic TG than the control group as well as a reduction in hepatomegaly and biomarkers of hepatocyte injury such as alanine and aspartate aminotransferases. Attenuation of hepatic steatosis by Nopal consumption was accompanied by a higher serum concentration of adiponectin and a greater abundance of mRNA for genes involved in lipid oxidation and lipid export and production of carnitine palmitoyltransferase-1 and microsomal TG transfer proteins in liver. Hepatic reactive oxygen species and lipid peroxidation biomarkers were significantly lower in rats fed Nopal compared with the control rats. Furthermore, rats fed the Nopal diet had a lower postprandial serum insulin concentration and a greater liver phosphorylated protein kinase B (pAKT):AKT ratio in the postprandial state. This study suggests that Nopal consumption attenuates hepatic steatosis by increasing fatty acid oxidation and VLDL synthesis, decreasing oxidative stress, and improving liver insulin signaling in obese Zucker (fa/fa) rats.
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Opuntia ficus indica (Nopal) Attenuates Hepatic Steatosis and Oxidative Stress in Obese Zucker
2012Co-Authors: Nimbe TorresAbstract:Nonalcoholic fatty liver disease (NAFLD) is associated with multiple factors such as obesity, insulin resistance, and oxidative stress. Nopal, a cactus plant widely consumed in the Mexican diet, is considered a functional food because of its antioxidant activity and ability to improve biomarkers of metabolic syndrome. The aim of this study was to assess the effect of Nopal consumption on the development of hepatic steatosis and hepatic oxidative stress and on the regulation of genes involved in hepatic lipid metabolism. Obese Zucker (fa/fa) rats were fed a control diet or a diet containing 4% Nopal for 7 wk. Rats fed the Nopal-containing diet had ;50% lower hepatic TG than the control group as well as a reduction in hepatomegaly and biomarkers of hepatocyte injury such as alanine and aspartate aminotransferases. Attenuation of hepatic steatosis by Nopal consumption was accompanied by a higher serum concentration of adiponectin and a greater abundance of mRNA for genes involved in lipid oxidation and lipid export and production of carnitine palmitoyltransferase1 and microsomal TG transfer proteins in liver. Hepatic reactive oxygen species and lipid peroxidation biomarkers were significantly lower in rats fed Nopal compared with the control rats. Furthermore, rats fed the Nopal diet had a lower postprandial serum insulin concentration and a greater liver phosphorylated protein kinase B (pAKT):AKT ratio in the postprandial state. This study suggests that Nopal consumption attenuates hepatic steatosis by increasing fatty acid oxidation and VLDL synthesis, decreasing oxidative stress, and improving liver insulin signaling in obese Zucker (fa/fa) rats. J. Nutr. 142: 1956‐1963, 2012.
Joseph A Caruso - One of the best experts on this subject based on the ideXlab platform.
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analysis of phytochelatins in Nopal opuntia ficus a metallomics approach in the soil plant system
Journal of Analytical Atomic Spectrometry, 2007Co-Authors: Julio Landero A Figueroa, Scott E Afton, Kazimierz Wrobel, Katarzyna Wrobel, Joseph A CarusoAbstract:This work focuses on phytochelatins (PCs) in plants chronically exposed to low or moderate metal concentrations in soil, which commonly occurs in natural environments. The original approach was to evaluate PCs in Nopal (Opuntia ficus) in relation to the plant and soil levels of Cd, Pb, Cu and Ag. These four metals were selected because of their known capability to induce PCs in plants and also because of their abundance in the region of Guanajuato (Mexico), where the Nopal plants were collected. ICP-MS determination of metals in Nopal roots, stems and in soil fractions provided information relevant to their bioavailability in soil as well as their uptake by Nopal. In search of a possible relationship between the parameters measured, correlation analysis was carried out (Cd was not considered owing to its low levels found in the plant tissues). The results obtained indicate that sequential metal leaching from soil does not always provide direct information on metal bioavailability. The uptake of metals by Nopal roots correlated with metals in the organic matter and sulfides fraction. Since low levels of humic substances were found in soil collected at cactus roots and because of the low solubility of Pb, Cu and Ag sulfides, the participation of rizosphere processes was suggested in facilitating metal uptake. Metal distribution in PC molecular mass fractions were studied by SEC-ICP-MS and the results compared with the total phytochelatin pool in plants as determined by reversed phase HPLC with spectrofluorimetric detection. The two procedures provide complementary analytical information when the global effect of all metals/metalloids present in soil on PC production is to be studied. Correlation analysis revealed the strong association of Pb with PCs both in roots and in stems, which demonstrates that Pb is important in Nopal PCs and suggests that Pb bound to PCs might be transported from roots to stems. For Cu, the correlation between metal-free PCs and metal bound to high molecular mass fraction of plant PC-rich extract was observed only in roots, suggesting differences in the transport of Pb and Cu. In contrast to these metals, no correlation was found for silver, suggesting no association with PCs, even though its elution with a high molecular mass fraction was observed in PC-rich plant extracts. The results obtained from this study indicate the complex role environmental conditions play in the accumulation of heavy metals and in phytochelatin production in the Opuntia genus.
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Analysis of phytochelatins in Nopal (Opuntia ficus): a metallomics approach in the soil–plant system
Journal of Analytical Atomic Spectrometry, 2007Co-Authors: Julio A. Landero Figueroa, Scott E Afton, Kazimierz Wrobel, Katarzyna Wrobel, Joseph A CarusoAbstract:This work focuses on phytochelatins (PCs) in plants chronically exposed to low or moderate metal concentrations in soil, which commonly occurs in natural environments. The original approach was to evaluate PCs in Nopal (Opuntia ficus) in relation to the plant and soil levels of Cd, Pb, Cu and Ag. These four metals were selected because of their known capability to induce PCs in plants and also because of their abundance in the region of Guanajuato (Mexico), where the Nopal plants were collected. ICP-MS determination of metals in Nopal roots, stems and in soil fractions provided information relevant to their bioavailability in soil as well as their uptake by Nopal. In search of a possible relationship between the parameters measured, correlation analysis was carried out (Cd was not considered owing to its low levels found in the plant tissues). The results obtained indicate that sequential metal leaching from soil does not always provide direct information on metal bioavailability. The uptake of metals by Nopal roots correlated with metals in the organic matter and sulfides fraction. Since low levels of humic substances were found in soil collected at cactus roots and because of the low solubility of Pb, Cu and Ag sulfides, the participation of rizosphere processes was suggested in facilitating metal uptake. Metal distribution in PC molecular mass fractions were studied by SEC-ICP-MS and the results compared with the total phytochelatin pool in plants as determined by reversed phase HPLC with spectrofluorimetric detection. The two procedures provide complementary analytical information when the global effect of all metals/metalloids present in soil on PC production is to be studied. Correlation analysis revealed the strong association of Pb with PCs both in roots and in stems, which demonstrates that Pb is important in Nopal PCs and suggests that Pb bound to PCs might be transported from roots to stems. For Cu, the correlation between metal-free PCs and metal bound to high molecular mass fraction of plant PC-rich extract was observed only in roots, suggesting differences in the transport of Pb and Cu. In contrast to these metals, no correlation was found for silver, suggesting no association with PCs, even though its elution with a high molecular mass fraction was observed in PC-rich plant extracts. The results obtained from this study indicate the complex role environmental conditions play in the accumulation of heavy metals and in phytochelatin production in the Opuntia genus.
Bret W Leslie - One of the best experts on this subject based on the ideXlab platform.
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alteration of uraninite from the Nopal i deposit pen a blanca district chihuahua mexico compared to degradation of spent nuclear fuel in the proposed u s high level nuclear waste repository at yucca mountain nevada
Applied Geochemistry, 1994Co-Authors: English C Pearcy, James D Prikryl, William M. Murphy, Bret W LeslieAbstract:Abstract At the Nopal I uranium deposit, primary uraninite (nominally UO 2+ x ) has altered almost completely to a suite of secondary uranyl minerals. The deposit is located in a Basin and Range horst composed of welded silicic tuff; uranium mineralization presently occurs in a chemically oxidizing and hydrologically unsaturated zone of the structural block. These characteristics are similar to those of the proposed U.S. high-level nuclear waste (HLW) repository at Yucca Mountain, Nevada. Petrographic analyses indicate that residual Nopal I uraninite is fine grained (5–10 μm) and has a low trace element content (average about 3 wt%). These characteristics compare well with spent nuclear fuel. The oxidation and formation of secondary minerals from the uraninite have occurred in an environment dominated by components common in host rocks of the Nopal I system (e.g. Si, Ca, K, Na and H 2 O) and also common to Yucca Mountain. In contrast, secondary phases in most other uranium deposits form from elements largely absent from spent fuel and from the Yucca Mountain environment (e.g. Pb, P and V). The oxidation of Nopal I uraninite and the sequence of alteration products, their intergrowths and morphologies are remarkably similar to those observed in reported corrosion experiments using spent fuel and unirradiated UO 2 under conditions intended to approximate those anticipated for the proposed Yucca Mountain repository. The end products of these reported laboratory experiments and the natural alteration of Nopal I uraninite are dominated by uranophane [nominally Ca(UO 2 ) 2 Si 2 O 7 ·6H 2 O] with lesser amounts of soddyite [nominally (UO 2 ) 2 SiO 4 ·2H 2 O] and other uranyl minerals. These similarities in reaction product occurrence developed despite the differences in time and physical—chemical environment between Yucca Mountain-approximate laboratory experiments and Yucca Mountain-approximate uraninite alteration at Nopal I, suggesting that the results may reasonably represent phases likely to form during long-term alteration of spent fuel in a Yucca Mountain repository. From this analogy, it may be concluded that the likely compositional ranges of dominant spent fuel alteration phases in the Yucca Mountain environment may be relatively limited and may be insensitive to small variations in system conditions.
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oxidative alteration of uraninite at the Nopal i deposit mexico possible contaminant transport and source term constraints for the proposed repository at yucca mountain
MRS Proceedings, 1992Co-Authors: Bret W Leslie, English C Pearcy, James D PrikrylAbstract:The Nopal I uranium deposit at Pena Blanca, Mexico is being studied as a natural analog of the proposed high-level nuclear waste repository at Yucca Mountain. Identification of secondary uranium phases at Nopal I, and the sequence of their formation after uraninite oxidation, provides insight into the source term for uranium, and suggests that uranophane may control uranium release and transport in a silici, tuffaceous, chemically oxidizing, and hydrologically unsaturated environment. Possible constraints on contaminant transport at Nopal I are derived from the spatial distribution of uranium and from measurements of {sup 238}U decay-series isotopes. The analyses indicate that flow of U-bearing fluids was influenced strongly by fracture density, but that the flow of these fluids was not restricted to fractures. Gamma spectroscopic measurements of {sup 238}U decay-series isotopes indicates secular equilibrium, which suggests undetectable U transport under present conditions.
