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Mg Content (mg + content)
Selected AbstractsRelationship between Carbon Isotope Discrimination and Mineral Content in Wheat Grown under Three Different Water RegimesJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2008L. Zhu Abstract Carbon isotope discrimination (,) has been proposed as an indirect selection criterion for transpiration efficiency and grain yield in wheat. However, because of the high cost for , analysis, attempts have been carried out to identify alternative screening criteria. Ash content (ma) has been proposed as an alternative criterion for , in wheat and barley. A pot experiment was conducted to analyse the relationship between , and ma in flag leaf and grain. Plants of 10 genotypes were cultivated under three different water regimes corresponding to moderate, intermediate and severe drought stress obtained by maintaining soil humidity at 75 %, 55 % and 45 % of the humidity at field capacity, respectively. , and ma in flag leaf and grain showed significant differences between the moderate, intermediate and severe drought stress levels. Significant correlations were found among genotypes for , and ma in flag leaf under severe drought stress, and for , and ma in grain under intermediate and moderate drought stress. In flag leaf at anthesis, , was negatively associated to K content and positively to Mg content. At maturity, , in grain was negatively correlated with Mg and Ca contents in flag leaf and grain, respectively. These results suggested that these traits may be potentially useful traits, which could be surrogates for ,. [source] Fabrication and Tunable Dielectric Properties of Magnesium-Doped Lead Barium Zirconate Thin FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2010Xihong Hao In present work, (Pb0.50Ba0.50)ZrO3 (PBZ) thin films doped by Mg from 0 to 5 mol% were deposited on Pt(111)/TiO2/SiO2/Si substrates by the sol,gel method. The phase structure of the Mg-doped PBZ thin films were characterized by X-ray diffraction. The electric-field and temperature-dependent electrical properties of the Mg-doped PBZ thin films were also investigated in detail. It was found that the Mg content had a strong influence on the dielectric properties of the thin films. The maximum values of dielectric permittivity and dielectric loss were obtained with 1 mol% Mg-doping PBZ thin films. However, the figure of merit (FOM) of the films was improved with increase in the Mg content. [source] Influence of Dietary Levels of Magnesium on Growth, Tissue Mineral Content, and Resistance of Channel Catfish Ictalurus punctatus Challenged with Edwardsiella ictaluriJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2003Chhorn Lim Juvenile channel catfish were fed purified diets supplemented with magnesium (Mg) from Mg sulfate at levels of 0, 200, 400, 600, 800, and 1,000 mg/kg and 0, 200, 400, 600, and 800 mg/kg in two separate feeding studies. In study I, the effect of dietary levels of Mg on growth response, vertebral mineral content, and macrophage chemotaxis were evaluated. Study II had similar objectives except that whole body mineral content was measured, and resistance of channel catfish to Edwardsiella ictaluri challenge was also determined. Fish with an average weight of 10.89 g were stocked at a rate of 50 fish/110-L aquarium (study I). In study II, fish with an average weight of 4.14 g were stocked at rates of 40 fish/110-L aquarium. Prior to stocking, each batch of fish was acclimated to laboratory conditions and fed the basal diet for 2 wk. The concentration of Mg in rearing water was 1.8 mg/L. Each diet was fed to fish in quadruplicate and triplicate aquaria to apparent satiation for 10 wk for studies I and II, respectively. Fish fed the basal diet started to die as early as 3 d after the study began (17 d of feeding the diet without Mg supplementation). In both studies, weight gain, survival, and feed efficiency were lowest for fish fed the basal diet but increased with increasing dietary levels of Mg. However, the differences between the values of each of these parameters for fish fed diets containing supplemental Mg were not always significant. Magnesium-deficiency signs observed were anorexia, sluggishness, convulsions, deformed snout, vertebral curvature, muscle flaccidity, and high mortality. Vertebral and whole body ash concentrations were high, but Mg content was low for fish fed the basal and the 200-mg Mg diets. Bone Ca content did not differ among fish fed different diets (study I), but whole body Ca tended to increase for fish fed the basal diet, suggesting the possibility of calcification of soft tissues. Macrophage chemotaxis in the presence of exoantigen was highest for fish fed diets supplemented with Mg at 400 and 200 mgkg for studies I and II, respectively. When expressed in terms of chemotaxis index, however, maximum or near maximum value was observed at a dietary Mg level of 400 mg/kg. Thus, a dietary level of Mg of 400 mg/kg from Mg sulfate was required for optimum growth and survival, maintaining high tissue levels of Mg, prevention of muscle flaccidity and skeletal deformity, and stimulating macrophage chemotaxis. Dietary levels of Mg had no effect on the resistance of juvenile channel catfish to Edwarsiella. ictaluri challenge. [source] Spectroscopic ellipsometry studies of Mg-doped ZnO thin films prepared by the sol,gel methodPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2009Shenghong Yang Abstract Zn1,xMgx O (ZMO) thin films with x = 0, 0.1, 0.2, and 0.3 were prepared on Si(100) substrates by the sol,gel method. The influence of Mg content on the structural and the optical properties was studied by X-ray diffraction and spectroscopic ellipsometry (SE) in the UV,visible region. The measured SE spectra were analyzed with an appropriate procedure to accurately determine the thickness and the optical constants of the thin films. It was found that the optical constants of the ZMO films are functions of the film composition. The refractive indices of the ZMO films decrease with increasing Mg content, and the optical bandgap energy exhibits nonlinear behavior or a bowing effect with the change of Mg mole fraction. A maximum band gap of ,3.91 eV was achieved at x = 0.3. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Enhancement of luminescence in ZnMgO thin-film nanophosphors and application for white light generationPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2008Santa Chawla Abstract A series of ZnMgO thin-film nanophosphors with varied Zn:Mg ratio has been prepared by chemical bath deposition. The structure, photoluminescence, time-resolved decay and chromaticity of the films are presented. ZnMgO films absorb light efficiently in the near UV (330,400 nm) and the emission covers a large part of the visible spectrum. Luminescence enhancement is maximum for 25% Mg. All ZnMgO films show luminescence lifetimes in the microsecond range while low Mg content (0,10%) films also exhibit fast decay (10,10 s). Measured colorimetric coordinates of (0.28, 0.32) when excited by 350 nm light make them suitable for generation of white light in conjunction with near UV LEDs. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Exciton localization in MgxZnyCd1,x,ySe alloyPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2004O. Maksimov Abstract We report photoluminescence and reflectivity measurements of MgxZnyCd1,x,ySe epitaxial layers (0 < x < 0.53) grown by molecular beam epitaxy on InP (100) substrates. Significant emission line broadening, increase in activation energy and Stokes shift are monitored with increasing Mg content. For MgxCdyZn1,x,ySe samples with large Mg content (x > 0.3), we observe an anomalous temperature dependence of both the emission energy and line broadening. This behavior is assigned to the emission from localized states. Different mechanisms of carrier localization are discussed and exciton localization on statistical CdSe clusters is proposed to be the most likely one. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth performance and tissue mineral content of juvenile grouper (Epinephelus coioides) fed diets supplemented with various levels of manganeseAQUACULTURE NUTRITION, Issue 6 2009C.-X. YE Abstract This study was conducted to investigate the effect of dietary manganese (Mn) on growth, vertebrae and whole-body Mn content of juvenile grouper, and to examine the effect of dietary Mn on copper (Cu), iron (Fe), zinc (Zn), calcium (Ca), phosphorus (P) and magnesium (Mg) content of vertebrae and whole body. Seven casein-gelatin-based diets were supplemented with 0, 5, 10, 15, 20, 50 and 1000 mg kg,1 of Mn from MnSO4·H2O. Grouper with an initial weight of 12.9 ± 0.4 g were fed to satiation with one of the seven diets for 8 weeks. Growth was not significantly affected by dietary Mn supplements. Vertebrae Mn increased from 31.7 to 118.1 mg kg,1 dry weight with dietary Mn supplement increasing from 0 to 50 mg kg,1 (y = ,0.0002x3 + 0.0162x2 + 1.3903x + 26.27, R2 = 0.9561, where y is the vertebrae Mn content and x is the dietary Mn content). Whole-body Mn increased from 2.5 to 7.8 mg kg,1 wet weight with dietary Mn supplement increasing from 0 to 50 mg kg,1 (y = 0.00001x3 , 0.00107x2 + 0.11054x + 2.24615, R2 = 0.9080, where y is the whole-body Mn content and x is the dietary Mn content). Dietary Mn had no significant effect on vertebrae Fe, Ca, P and Mg content, and whole-body Cu, Zn and Mg content. However, vertebrae Zn and whole body Ca, P were highest in fish fed diet supplemented with 15 mg kg,1 of Mn. Based on this, Mn supplement of 15 mg kg,1 might be the optimum when the basal diet contained 4 mg kg,1 of Mn. Fish fed diet supplemented with 1000 mg kg,1 of Mn did not show any gross abnormality or change in feeding behaviour, but Mn contents of vertebrae and whole body were as high as 695.1 mg kg,1 dry weight and 42.5 mg kg,1 wet weight, respectively. Also, whole body Fe decreased significantly when Mn supplement was up to 1000 mg kg,1. [source] Spectral reflectance-compositional properties of spinels and chromites: Implications for planetary remote sensing and geothermometryMETEORITICS & PLANETARY SCIENCE, Issue 4 2004Edward A. Cloutis These two groups of minerals are spectrally distinct, which relates largely to differences in the types of major cations present. Both exhibit a number of absorption features in the 0.3,26 ,m region that show systematic variations with composition and can be used to quantify or constrain certain compositional parameters, such as cation abundances, and site occupancies. For spinels, the best correlations exist between Fe2+ content and wavelength positions of the 0.46, 0.93, 2.8, Restrahelen, 12.3, 16.2, and 17.5 ,m absorption features, Al and Fe3+ content with the wavelength position of the 0.93 ,m absorption feature, and Cr content from the depth of the absorption band near 0.55 ,m. For chromites, the best correlations exist between Cr content and wavelength positions of the 0.49, 0.59, 2, 17.5, and 23 ,m absorption features, Fe2+ and Mg contents with the wavelength position of the 1.3 ,m absorption feature, and Al content with the wavelength position of the 2 ,m absorption feature. At shorter wavelengths, spinels and chromites are most readily distinguished by the wavelength position of the absorption band in the 2 ,m region (<2.1 ,m for spinels, >2.1 ,m for chromite), while at longer wavelengths, spectral differences are more pronounced. The importance of being able to derive compositional information for spinels and chromites from spectral analysis stems from the relationship between composition and petrogenetic conditions (pressure, temperature, oxygen fugacity) and the widespread presence of spinels and chromites in the inner solar system. When coupled with the ability to derive compositional information for mafic silicates from spectral analysis, this opens up the possibility of deriving petrogenetic information for remote spinel- and chromite-bearing targets from analysis of their reflectance spectra. [source] Tree Diversity, Forest Structure and Productivity along Altitudinal and Topographical Gradients in a Species-Rich Ecuadorian Montane Rain ForestBIOTROPICA, Issue 2 2010Jürgen Homeier ABSTRACT We studied the spatial heterogeneity of tree diversity, and of forest structure and productivity in a highly diverse tropical mountain area in southern Ecuador with the aim of understanding the causes of the large variation in these parameters. Two major environmental gradients, elevation and topography, representing a broad range of climatic and edaphic site conditions, were analyzed. We found the highest species richness of trees in valleys <2100 m. Valleys showed highest values of basal area, leaf area index and tree basal area increment as well. Tree diversity also increased from ridges to valleys, while canopy openness decreased. Significant relationships existed between tree diversity and soil parameters (pH, total contents of Mg, K, Ca, N and P), and between diversity and the spatial variability of pH and Ca and Mg contents suggesting a dependence of tree diversity on both absolute levels and on the small-scale heterogeneity of soil nutrient availability. Tree diversity and basal area increment were positively correlated, partly because both are similarly affected by soil conditions. We conclude that the extraordinarily high tree species richness in the area is primarily caused by three factors: (1) the existence of steep altitudinal and topographic gradients in a rather limited area creating a small-scale mosaic of edaphically different habitats; (2) the intermingling of Amazonian lowland plant species, that reach their upper distribution limits, and of montane forest species; and (3) the geographical position of the study area between the humid eastern Andean slope and the dry interandean forests of South Ecuador. [source] | |||||||||||||