832 resultados para Salt marsh and semi-arid


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The methanol-chloroform extract of the marine red alga, Rhodomela confervoides, was measured for antioxidant activity, using the alpha,alpha-diphenyl-beta-picrylhydrazyl radical-scavenging assay and the beta-carotene-linoleate bleaching assay systems, and compared with those of the positive Controls of butylated hydroxytoluene, gallic acid and ascorbic acid, The active extract was further purified by liquid-liquid partition to afford four fractions, of which the ethyl acetate-soluble (EA) fraction exhibited the strongest antioxidant activity in both assay systems. This fraction was further divided into seven subfractions, designated as EA1-EA7, by silica gel vacuum liquid chromatography. in most cases, EA1 and EM Were found to possess the strongest activity. The total phenolic contents and reducing powers of the extract, fractions, and subfractions were also determined. Significant associations between the antioxidant potency and the total phenolic content, as well as between the antioxidant potency and the reducing power, were found for the tested fractions and subfractions. (c) 2008 Elsevier Ltd. All rights reserved.

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CoWO4 nano-particles were successfully synthesized at a low temperature of 270 degrees C by a molten salt method, and effects of such processing parameters as holding time and salt quantity on the crystallization and development Of CoWO4 crystallites were initially studied. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM). and photoluminescent spectra techniques (PL), respectively. Experimental results showed that the well-crystallized CoWO4 nano-particles with ca. 45 nm in diameter could be obtained at 270 degrees C for a holding time of 8 h with 6:1 mass ratio of the salt to CoWO4 precursor, and XRD analysis evidenced that the as-prepared sample was a pure monoclinic phase Of CoWO4 with wolframite structure. Their PL spectra revealed that the CoWO4 nano-particles displayed a very strong PL peak at 453 nm with the excitation wavelength of 230 nm, and PL properties of CoWO4 crystallites relied on their crystalline state, especially on their particle size. (C) 2009 Elsevier B.V. All rights reserved.

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The paper systematically discusses the mechanism for glycinebetaine to improve plant salt resistance and its research advances in genetic engineering at home and abroad as well as summarizing the research progresses about the key enzymes and their genetic engineering in glycinebetaine biosynthesis. It suggests that on the basis of further understanding the mechanism for glycinebetaine to improve plant salt resistance,the transformation of the genes relating to glycinebetaine biosynthesis should be carried out in major crops so that new plant varieties resistant to salt can be obtained.

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Six domestic yaks aged 6 years, comprising three culling male and three culling female yaks, from the Qinghai Lake area and three male semi-wild yaks aged 6 months from Datong Yak Farm were used to detect the levels of amino acids, mineral elements, residual heavy metals and pesticides in yak meat. The results showed that there was little difference in amino acid levels for different types of yak by age and sex. The meat of the adult male yak was 7.35 mg/kg higher in calcium (P < 0.05) and 124 mg/kg higher in phosphorus (P < 0.01) than that of the adult female yak. There was an obvious difference in zinc content, and there was also a significant difference for copper and sulfur between adult male and female yaks (P < 0.01). Iron was 8.85 mg/kg higher in semi-wild yaks than in domestic yaks, but there were no differences for other minerals. The levels of residual heavy metals and residual pesticides were well within those allowed by the National Standard of China. Furthermore, the data showed that introducing wild yak's blood did not result in a quality change in the domestic yak meat. Yak meat from Qinghai Plateau has the characteristics of being non-polluted and rich in amino acids in comparison with local yellow cattle meat.

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This work presents computation analysis of levitated liquid thermal and flow fields with free surface oscillations in AC and DC magnetic fields. The volume electromagnetic force distribution is continuously updated with the shape and position change. The oscillation frequency spectra are analysed for droplets levitation against gravity in AC and DC magnetic fields at various combinations. For larger volume liquid metal confinement and melting the semi-levitation induction skull melting process is simulated with the same numerical model. Applications are aimed at pure electromagnetic material processing techniques and the material properties measurements in uncontaminated conditions.

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This short position paper considers issues in developing Data Architecture for the Internet of Things (IoT) through the medium of an exemplar project, Domain Expertise Capture in Authoring and Development ­Environments (DECADE). A brief discussion sets the background for IoT, and the development of the ­distinction between things and computers. The paper makes a strong argument to avoid reinvention of the wheel, and to reuse approaches to distributed heterogeneous data architectures and the lessons learned from that work, and apply them to this situation. DECADE requires an autonomous recording system, ­local data storage, semi-autonomous verification model, sign-off mechanism, qualitative and ­quantitative ­analysis ­carried out when and where required through web-service architecture, based on ontology and analytic agents, with a self-maintaining ontology model. To develop this, we describe a web-service ­architecture, ­combining a distributed data warehouse, web services for analysis agents, ontology agents and a ­verification engine, with a centrally verified outcome database maintained by certifying body for qualification/­professional status.

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Salt weathering is a crucial process that brings about a change in stone, from the scale of landscapes to stone outcrops and natural building stone facades. It is acknowledged that salt weathering is controlled by fluctuations in temperature and moisture, where repeated oscillations in these parameters can cause re-crystallisation, hydration/de-hydration of salts, bringing about stone surface loss in the form of, for example, granular disaggregation, scaling, and multiple flaking. However, this ‘traditional’ view of how salt weathering proceeds may need to be re-evaluated in the light of current and future climatic trends. Indeed, there is considerable scope for the investigation of consequences of climate change on geomorphological processes in general. Building on contemporary research on the ‘deep wetting’ of natural building stones, it is proposed that (as stone may be wetter for longer), ion diffusion may become a more prominent mechanism for the mixing of molecular constituents, and a shift in focus from physical damage to chemical change is suggested. Data from ion diffusion cell experiments are presented for three different sandstone types, demonstrating that salts may diffuse through porous stone relatively rapidly (in comparison to, for example, dense concrete). Pore water from stones undergoing diffusion experiments was extracted and analysed. Factors controlling ion diffusion
relating to ‘time of wetness’ within stones are discussed, (continued saturation, connectivity of pores, mineralogy, behaviour of salts, sedimentary structure), and potential changes in system dynamics as a result of climate change are addressed. System inputs may change in terms of increased moisture input, translating into a greater depth of wetting front. Salts are likely to be ‘stored’ differently in stones, with salt being in solution for longer periods (during prolonged winter wetness). This has myriad implications in terms of the movement of ions by diffusion and the potential for chemical change in the stone (especially in more mobile constituents), leading to a weakening of the stone matrix/grain boundary cementing. The ‘output’ may be mobilisation and precipitation of elements leading to, for example, uneven cementing in the stone. This reduced strength of the stone, or compromised ability of the stone to absorb stress, is likely to make crystallisation a more efficacious mechanism of decay when it does occur. Thus, a delay in the onset of crystallisation while stonework is wet does not preclude exaggerated or accelerated material loss when it finally happens.

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In this paper, we have reported the CO2 solubility in different pure alkyl carbonate solvents (EC, DMC, EMC, DEC) and their binary mixtures as EC/DMC, EC/EMC, and EC/DEC and for electrolytes [solvent + lithium salt] LiX (X = LiPF6, LiTFSI, or LiFAP) as a function of the temperature and salt concentration. To understand the parameters that influence the structure of the solvents and their ability to dissolve CO2, through the addition of a salt, we first analyzed the viscosities of EC/DMC + LiX mixtures by means of a modified Jones–Dole equation. The results were discussed considering the order or disorder introduced by the salt into the solvent organization and ion solvation sphere by calculating the effective solute ion radius, rs. On the basis of these results, the analysis of the CO2 solubility variations with the salt addition was then evaluated and discussed by determining specific ion parameters Hi by using the Setchenov coefficients in solution. This study showed that the CO2 solubility has been affected by the shape, charge density, and size of the ions, which influence the structuring of the solvents through the addition of a salt and the type of solvation of the ions.

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Elemental and semi-elemental formulas are used to feed infants with short bowel syndrome, who may not be able to tolerate feeds of more than 310 mOsm kg(-1). The present study aimed to measure the osmolality of elemental and semi-elemental formulas at different concentrations, with and without the addition of nonprotein energy supplements.

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We study the phonon dispersion, cohesive and thermal properties of raxe gas solids Ne, Ar, Kr, and Xe, using a variety of potentials obtained from different approaches; such as, fitting to crystal properties, purely ab initio calculations for molecules and dimers or ab initio calculations for solid crystalline phase, a combination of ab initio calculations and fitting to either gas phase data or sohd state properties. We explore whether potentials derived with a certain approaxih have any obvious benefit over the others in reproducing the solid state properties. In particular, we study phonon dispersion, isothermal ajid adiabatic bulk moduli, thermal expansion, and elastic (shear) constants as a function of temperatiue. Anharmonic effects on thermal expansion, specific heat, and bulk moduli have been studied using A^ perturbation theory in the high temperature limit using the neaxest-neighbor central force (nncf) model as developed by Shukla and MacDonald [4]. In our study, we find that potentials based on fitting to the crystal properties have some advantage, particularly for Kr and Xe, in terms of reproducing the thermodynamic properties over an extended range of temperatiures, but agreement with the phonon frequencies with the measured values is not guaranteed. For the lighter element Ne, the LJ potential which is based on fitting to the gas phase data produces best results for the thermodynamic properties; however, the Eggenberger potential for Ne, where the potential is based on combining ab initio quantum chemical calculations and molecular dynamics simulations, produces results that have better agreement with the measured dispersion, and elastic (shear) values. For At, the Morse-type potential, which is based on M0ller-Plesset perturbation theory to fourth order (MP4) ab initio calculations, yields the best results for the thermodynamic properties, elastic (shear) constants, and the phonon dispersion curves.