The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
Khursheed N. Jeejeebhoy - One of the best experts on this subject based on the ideXlab platform.
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The Role of Chromium in Nutrition and Therapeutics and as a Potential Toxin
Nutrition reviews, 2009Co-Authors: Khursheed N. JeejeebhoyAbstract:Since the 1950s it has been known that Chromium is important for the expression of glucose tolerance and that in Chromium Deficiency the use of glucose is impaired. Chromium has been recognized as an essential nutrient since the finding of low-molecular-weight Chromium as a biological modifier of insulin action and the clinical demonstration of Deficiency associated with glucose intolerance that responded to the administration of Chromium. The major impediment to the use of orally administered Chromium is poor absorption of trivalent Chromium in its inorganic form. Trivalent Chromium is more available in yeast and, more recently, as Chromium picolinate for oral absorption. The widespread use of these supplements has resulted in controversy regarding Chromium's role as a nutrient, its use for treatment of insulin resistance, and its potential toxicity. This report reviews the evidence for the potential toxicity of Chromium supplements in contrast with its usefulness as a nutrient or therapeutic agent in the treatment or prevention of insulin resistance.
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Neurologic Symptoms Due to Possible Chromium Deficiency in Long-Term Parenteral Nutrition That Closely Mimic Metronidazole-Induced Syndromes
JPEN. Journal of parenteral and enteral nutrition, 1996Co-Authors: Albert H. Verhage, Wei K. Cheong, Khursheed N. JeejeebhoyAbstract:Background: We previously described a patient on home parenteral nutrition (HPN) who developed glucose intolerance and neuropathy that only responded to an infusion of Chromium. A patient on HPN who had neuropathy and glucose intolerance was studied. He was also on metronidazole, which could have caused the neuropathy, but the symptoms and signs persisted. Methods: Baseline clinical examination, nerve conduction studies, serum vitamin and trace element levels, and glucose tolerance were measured. Then, 250 μg of trivalent Chromium as the chloride salt was infused daily for 2 weeks. The above studies were repeated. Results: The patient at baseline had peripheral neuropathy of the axonal type and was glucose intolerant. Serum Chromium was raised in this patient above the reference range. Despite raised serum levels, the infusion of Chromium resulted in clinical remission that was marked 4 days after starting the infusion. Normalization of nerve conduction also occurred within 3 weeks of the initial study. C...
Nigel M. Sammes - One of the best experts on this subject based on the ideXlab platform.
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Sintering and thermal expansion characterization of Al-doped and Co-doped lanthanum strontium chromites synthesized by the Pechini method
Solid State Ionics, 2001Co-Authors: Masashi Mori, Nigel M. SammesAbstract:Abstract The air-sintering and thermal expansion characteristics of Al-doped and Co-doped lanthanum strontium chromites synthesized by the Pechini method have been discussed as interconnect materials in high-temperature solid oxide fuel cells (SOFC). Fine perovskite powders with an average particle size of 0.24 μm, and with a surface area of 3.5 m2/g, calcined at 800 °C for 1 h, were obtained. After the Co-doped samples were heated at 1600 °C for 10 h, surface analysis showed the materials to have a densely packed structure with little sign of porosity. It was, however, found that large pores remained inside the samples. By energy dispersive X-ray analysis, it was clarified that the composition on the surface shifted to a B-site lean region by cobalt-vaporization. The La0.9Sr0.1Cr0.95Al0.02Co0.02O3 sample with a slight Chromium-Deficiency enhanced bulk diffusion sintering, and showed the relative densities to be ≥94% when sintered at 1600 °C for 20 h. The average thermal expansion coefficient (TEC) of this material in the temperature range from 50 to 1000 °C was 10.4×10−6/°C in air and 11.2×10−6/°C in a H2 atmosphere. The La0.9Sr0.1Cr0.95Al0.02Co0.02O3 powder synthesized by the Pechini method is the one that is suitable for use as the interconnect material for solid oxide fuel cells.
Yu Shen - One of the best experts on this subject based on the ideXlab platform.
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Sintering, transport properties and thermal expansion of Cr-deficient Nd0.75Sr0.25Cr1−δO3 solid solutions
Journal of Alloys and Compounds, 2009Co-Authors: Monan Liu, Yu ShenAbstract:Abstract Chromium-deficient Nd 0.75 Sr 0.25 Cr 1− δ O 3 (0.02 ≤ δ ≤ 0.06) solid solutions were prepared using a conventional solid-state reaction. The effects of Chromium-Deficiency content on sintering, transport properties and thermal expansion of the solid solutions were investigated. The results showed that all the solid solutions present single phase orthorhombic perovskite structure at room temperature. The cell volume and the electrical conductivity of Nd 0.75 Sr 0.25 Cr 1− δ O 3 solid solutions decrease with the increase of Cr vacancy content. The Nd 0.75 Sr 0.25 Cr 0.98 O 3 sample exhibits the best properties. The relative density is 95.5%, and the electrical conductivity and thermal expansion coefficient (TEC) reach 18.8 S cm −1 at 850 °C and 9.62 × 10 −6 K −1 in the temperature range of 30–1000 °C in air, respectively. Compared with Nd 0.75 Sr 0.25 CrO 3 , TEC of the Nd 0.75 Sr 0.25 Cr 0.98 O 3 sample is more compatible with that of yttria stabilized zirconia (10.3 × 10 −6 K −1 ). Sintering, electrical and thermal expansion properties all indicate that Nd 0.75 Sr 0.25 Cr 0.98 O 3 can be a promising candidate for interconnect material application in solid oxide fuel cells.
M P Vaquero - One of the best experts on this subject based on the ideXlab platform.
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Magnesium and trace elements in the elderly: intake, status and recommendations.
The journal of nutrition health & aging, 2002Co-Authors: M P VaqueroAbstract:Imbalances between mineral intakes and recommended amounts have been observed in different groups of elderly subjects. Nevertheless, assessment of the status of magnesium and trace elements in the elderly is difficult, even for iron because infection and inflammation increases ferritin. Mineral bioavailability may change due to ageing. Therefore, formulation of mineral recommendations is complex and individual recommendations are sometimes necessary. A number of surveys show magnesium, zinc, selenium and Chromium intakes by old persons to be lower than the corresponding reference nutrient intakes. Contrarily, intakes of iron are generally adequate or higher than recommended, and it has been suggested that increased storage of iron in the elderly may be related with the development of age-related diseases through the increase in oxidative stress. Low iron status together with iron excess may be common in an elderly population. The same applies for zinc. Magnesium and selenium deficiencies among the elderly are also well documented, especially among the institutionalised and people with pathologies. Chromium Deficiency is associated with type II diabetes mellitus. Recommended iron intake is lower for elderly women compared to young, because menstruation ceases after menopause, but in old men, it is similar to that of young men. Dietary Reference Values for the rest of the elements are similar to those of adults, although several suggestions have been made about the quantities. This review examines various aspects of the changes in mineral bioavailability due to ageing, of data published on mineral intakes and status, and finally the dietary recommendations for this vulnerable population group.
Xin Zhang - One of the best experts on this subject based on the ideXlab platform.
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Microstructure and phases of deposited metal of SUPER304H steel under high temperature Persistent stress.
Scientific reports, 2018Co-Authors: Xin ZhangAbstract:In order to investigate the high temperature rupture property of deposited metal of SUPER304H steel, the high temperature tensile test was carried out, and the microstructure transformation of deposited metal of SUPER304H steel under high temperature persistent stress were studied. Most of the solidification subgrain boundaries dissolve. The effect of the high temperature enduring on the microstructure is not obvious. Temperature and time are the main factors that influence the change of microstructure. Under the action of high temperature stress, the corrosion resistance of austenite decreases significantly due to the occurrence of Chromium Deficiency. With the persistent stress of 200 MPa, the precipitated phase of deposited metal is Nb (C, N), M23C6, NbCrN phase, and a certain amount of alpha phase is precipitated in the deposited metal with a persistent stress of 78 MPa. The precipitation of M23C6 phase is the main reason for the decrease of the corrosion resistance, especially the decrease of the corrosion resistance.