Sigma-Aldrich

氧化镁 ≥99.99% trace metals basis; CAS Number: 1309-48-4; EC Number: 215-171-9; Linear Formula: MgO; find Sigma-Aldrich-529699 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich

氧化镁 ≥99.99% trace metals basis | Sigma-Aldrich

氧化镁 &#8805;99.99% trace metals basis

氧化镁

Medical treatments for the maintenance therapy of reflux oesophagitis and endoscopic negative reflux disease

Magnesium oxide nanoparticles prepared by ultrasound enhanced hydrolysis of Mg-alkoxides

Magnesium oxide/water chemical heat pump to enhance energy utilization of a cogeneration system

Hydration of refractory oxides in castable bond systems?I: alumina, magnesia, and alumina-magnesia mixtures

Lithium carbonate and lithium oxalate were incorporated as leachable corrosion inhibitors in model organic coatings for the protection of AA2024-T3. The coated samples were artificially damaged with a scribe. It was found that the lithium-salts are able to leach from the organic coating and form a protective layer in the scribe on AA2024-T3 under neutral salt spray conditions. The present paper shows the first observation and analysis of these corrosion protective layers, generated from lithium-salt loaded organic coatings. The scribed areas were examined by scanning and transmission electron microscopy before and after neutral salt spray exposure (ASTM-B117). The protective layers typically consist of three different layered regions, including a relatively dense layer near the alloy substrate, a porous middle layer and a flake-shaped outer layer, with lithium uniformly distributed throughout all three layers. Scanning electron microscopy and white light interferometry surface roughness measurements demonstrate that the formation of the layer occurs rapidly and, therefore provides an effective inhibition mechanism. Based on the observation of this work, a mechanism is proposed for the formation of these protective layers.

The corrosion protection of AA2024-T3 aluminium alloy by leaching of lithium-containing salts from organic coatings.

Adsorbed molecules are involved in many reactions on solid surface that are of great technological importance. As such, there has been tremendous effort worldwide to learn how to predict reaction rates and equilibrium constants for reactions involving adsorbed molecules. Theoretical calculation of both the rate and equilibrium constants for such reactions requires knowing the entropy and enthalpy of the adsorbed molecule. While much effort has been devoted to measuring and calculating the enthalpies of well-defined adsorbates, few measurements of the entropies of adsorbates have been reported. We present here a new way to determine the standard entropies of adsorbed molecules (S(ad)(0)) on single crystal surfaces from temperature programmed desorption data, prove its accuracy by comparison to entropies measured by equilibrium methods, and apply it to published data to extract new entropies. Most importantly, when combined with reported entropies, we find that at high coverage, they linearly track the entropy of the gas-phase molecule at the same temperature (T), such that S(ad)(0)(T) = 0.70 S(gas)(0)(T) - 3.3R (R = the gas constant), with a standard deviation of only 2R over a range of 50R. These entropies, which are ~2/3 of the gas, are huge compared to most theoretical predictions. This result can be extended to reliably predict prefactors in the Arrhenius rate constant for surface reactions involving such species, as proven here for desorption.

The entropies of adsorbed molecules.

Heat stress is a critical threat to tall fescue in transitional and warm climate zones. Identification of association between molecular markers and heat tolerance-related functional traits would promote the efficient selection of heat tolerant tall fescue cultivars. Association analysis of heat tolerance-related traits was conducted in 100 diverse tall fescue accessions consisting of 93 natural genotypes originating from 33 countries and 7 turf-type commercial cultivars. The panel displayed significant genetic variations in growth rate (GR), turfgrass quality (TQ), survival rate (SR), chlorophyll content (CHL) and evapotranspiration rate (ET) in greenhouse and growth chamber trials. Two subpopulations were detected in the panel of accessions by 1010 SSR alleles with 90 SSR markers, but no obvious relative kinship was observed. 97 and 67 marker alleles associated with heat tolerance-related traits were identified in greenhouse trial and growth chamber trial (P < 0.01) using mix linear model, respectively. Due to different experimental conditions of the two trials, 2 SSR marker alleles associated with GR and ET were simultaneously identified at P < 0.01 level in two trials in response to heat stress. High-temperature induced great variations of functional traits in tall fescue accessions. And the identified marker alleles associated with functional traits could provide important information about heat tolerance genetic pathways, and be used for molecular assisted breeding to enhance tall fescue performance under heat stress.

Association of SSR markers with functional traits from heat stress in diverse tall fescue accessions.

Atomic scale characterization of the structure and dynamics of confined water molecules located near the metal oxide-aqueous interface is carried out using molecular dynamics simulations. Proximity effects on water molecules (H(2)O) near a magnesium oxide surface (MgO(100)) at room temperature are evaluated based on various structural and dynamical correlation functions. Translational and orientational order parameters are used to quantify the extent of ordering of water molecules near the oxide surface. There is significant ordering of water molecules in the two layers close to the oxide interface and the extent of ordering decreases with increasing distance from the oxide-water interface. The characteristic structural features of proximal water molecules near oxide-aqueous interfaces are strongly correlated to their vibrational densities of states. Systematic trends in libration, bending, and stretching bands are correlated with local ordering of water molecules and the hydrogen-bonding network. We find that restricted transverse oscillations result in larger blue shifts in O-O-O bending and O-O stretching bands for water molecules having increased proximity to the interface. The O-H stretching band is red-shifted whereas the libration bands for proximal water are blue shifted with respect to bulk water; the extent of shifts are sensitive to the interface proximity, their local confinement and their hydrogen bonding status.

Atomic scale characterization of interfacial water near an oxide surface using molecular dynamics simulations.

This work describes the structural changes of bagasse hemicelluloses during the cooking process involving active oxygen (O(2) and H(2)O(2)) and solid alkali (MgO). The hemicelluloses obtained from the bagasse raw material, pulp, and yellow liquor were analyzed by high-performance anion-exchange chromatography (HPAEC), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), and (1)H-(13)C 2D hetero-nuclear single quantum coherence spectroscopy (HSQC). The results revealed that the structure of the bagasse hemicelluloses was L-arabino-(4-O-methylglucurono)-D-xylan. Some sugar units in hemicelluloses were oxidized under the cooking conditions. Additionally, the backbones and the ester linkages of hemicelluloses were heavily cleaved during the cooking process.

The structural changes of the bagasse hemicelluloses during the cooking process involving active oxygen and solid alkali.

High-silica zeolites have been reported recently as efficient catalysts for liquid- and gas-phase condensation reactions because of the presence of a complementary source of basicity compared to Al-rich basic zeolites. Herein, we describe the controlled generation of these active sites on silica-rich FAU, BEA, and MFI zeolites. Through the application of a mild base treatment in aqueous Na2CO3, alkali-metal-coordinating defects are generated within the zeolite whereas the porous properties are fully preserved. The resulting catalysts were applied in the gas-phase condensation of propanal at 673 K as a model reaction for the catalytic upgrading of pyrolysis oil, for which an up to 20-fold increased activity compared to the unmodified zeolites was attained. The moderate basicity of these new sites leads to a coke resistance superior to traditional base catalysts such as CsX and MgO, and comparable activity and excellent selectivity is achieved for the condensation pathways. Through strategic acid and base treatments and the use of magic-angle spinning NMR spectroscopy, the nature of the active sites was investigated, which supports the theory of siloxy sites as basic centers. This contribution represents a key step in the understanding and design of high-silica base catalysts for the intermediate deoxygenation of crude bio-oil prior to the hydrotreating step for the production of second-generation biofuels.

Generation of basic centers in high-silica zeolites and their application in gas-phase upgrading of bio-oil.

Transverse magnetothermoelectric effects are studied in Permalloy thin films grown on MgO and GaAs substrates and compared to those grown on suspended SiN(x) membranes. The transverse voltage along platinum strips patterned on top of the Permalloy films is measured versus the external magnetic field as a function of the angle and temperature gradients. After the identification of the contribution of the planar and anomalous Nernst effects, we find an upper limit for the transverse spin Seebeck effect, which is several orders of magnitude smaller than previously reported.

Transverse spin Seebeck effect versus anomalous and planar Nernst effects in Permalloy thin films.

In this paper, we report on the simple, reliable synthesis of polypyrrole (PPy)/graphene oxide (GO) composite nanosheets by using sacrificial-template polymerization method. Herein, MnO(2) nanoslices were chosen as a sacrificial-template to deposit PPy, which served as the oxidant as well. During the polymerization of pyrrole on surface of GO nanosheets, MnO(2) component was consumed incessantly. As a result, the PPy growing on the surface of GO nanosheets has the morphology just like the MnO(2) nanoslices. This method can provide the fabrication of PPy nanostructures more easily than conventional route due to its independence of removing template, which usually is a complex and tedious experimental process. The as-prepared PPy/GO composite nanosheets exhibited an enhanced properties for Cr(VI) ions removal in aqueous solution based on the synergy effect. The adsorption capacity of the PPy/GO composite nanosheets is about two times as large as that of conventional PPy nanoparticles. We believe that our findings can open a new and effective avenue to improve the adsorption performance in removing heavy metal ions from waste water.

Fabrication of polypyrrole/graphene oxide composite nanosheets and their applications for Cr(VI) removal in aqueous solution.

A new catalyst composed of Pd nanoparticles supported on MgO has been prepared by the room temperature NaBH(4) reduction of Na(2)PdCl(4) in methanol in the presence of the support. TEM measurements reveal well-dispersed Pd particles of mean diameter 1.7 nm attached to the MgO surface. Further characterization was achieved by ICP-AES, XPS, XRD, H(2) pulse chemisorption and H(2)-TPR. The new catalyst is efficient for the regioselective hydrogenation of the heterocyclic ring of quinolines, as well as for the mild reduction of a variety of alkenes representative of fuel components, and the partial saturation of biodiesel. The new material is considerably more reactive than commercial Pd/SiO(2) and Pd/Al(2)O(3) catalysts under analogous reaction conditions.

Hydrogenation of quinolines, alkenes, and biodiesel by palladium nanoparticles supported on magnesium oxide.

Peas are increasing in popularity as a source of carbohydrate, protein and fibre in extruded canine diets. The aim of this study was to test the health effects of two canine diets with identical macronutrient profiles, but containing either yellow field peas or white rice as the carbohydrate source on metabolism, cardiovascular outcomes and adiposity. First, the acute glycemic, insulinemic and cardiovascular responses to the pea- or rice-based diets were determined in normal weight beagles (n = 7 dogs). The glycemic index did not differ between the pea diet (56 ± 12) and rice diet (63 ± 9). Next, obese beagles (n = 9) were fed the yellow field pea diet or white rice diet ad libitum for 12 weeks in a crossover study. Adiposity (measured using computed tomography), metabolic (oral glucose tolerance test, plasma leptin, adiponectin, C-reactive protein) and cardiovascular assessments (echocardiography and blood pressure) were performed before and after each crossover study period. After 12 weeks on each diet, peak insulin (p = 0.05) and area under the curve (AUC) for insulin after a 10 g oral glucose tolerance test (p = 0.05) were lower with the pea than the rice diet. Diet did not show a significant effect on body weight, fat distribution, cardiovascular variables, adiponectin or leptin. In conclusion, a diet containing yellow field peas reduced the postprandial insulin response after glucose challenge in dogs despite continued obesity, indicating improved metabolic health.

Effect of an extruded pea or rice diet on postprandial insulin and cardiovascular responses in dogs.

A novel organic-inorganic platform comprising of chitosan (CH) modified nanostructured magnesium oxide (nanoMgO) has been electrophoretically deposited on the indium-tin-oxide (ITO) substrate. The single stranded probe DNA (ssDNA) sequence of Vibrio cholerae has been covalently functionalized onto CH-nanoMgO/ITO surface. The cytotoxicity assay of nanoMgO particles, examined using human intestinal cell line (INT 407), reveals no significant cytotoxicity at the given doses in the range of 50-350 μg/mL. The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and various microscopic techniques have been employed for the structural and morphological analysis of the fabricated electrodes. The electrochemical response studies of ssDNA and fragmented genomic DNA hybridized electrode (dsGDNA/CH-nanoMgO/ITO) have been carried out using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The dsGDNA/CH-nanoMgO/ITO bioelectrode exhibits a linear response in the range 100-500 ng/μL with improved sensitivity of 36.72 nA/ng/cm(2), faster response time of 3s and high stability of 3-4 months under refrigerated condition. The lower detection limit of fabricated genosensor has been estimated as 35.20 ng/μL and it shows good reproducibility/repeatability.

Biocompatible nanostructured magnesium oxide-chitosan platform for genosensing application.

The cooking with solid alkali and active oxygen has a high selectivity for delignification. In the present work, the O(2) and H(2)O(2) were separately combined with MgO used in cornstalk cooking for investigating their effects on delignification. After cooking, the lignins in raw material, pulp, and yellow liquor were all characterized by HSQC NMR. The results showed that the syringyl (S/S'/S″) units and β-O-4' (A/A'/A″) structures had different reactivity in the cooking with MgO and H(2)O(2) due to their different structures on side-chains. Whereas the syringyl (S/S'/S″) units could be completely decomposed when the MgO and O(2) were used, and the β-O-4' (A/A'/A″) structures could be partly degraded. A novel structure G' unit with a carbonyl group was only generated in the cooking with MgO and O(2). In addition, the H unit, non-phenolic β-β' (B) and β-5' (C) structures were all stable in both of the two cooking processes.

Characterization of changes of lignin structure in the processes of cooking with solid alkali and different active oxygen.

Titanium dioxide is an important and widely studied photocatalytic material, but to achieve photocatalytic activity under visible-light absorption, it needs to have a narrower band gap and reduced charge carrier recombination. First-principles simulations are presented in this paper to show that heterostructures of rutil TiO₂ modified with nanoclusters of MgO and Ga₂O₃ will be new photocatalytically active materials in the UV (MgO-TiO₂) and visible (Ga₂O₃-TiO₂) regions of the solar spectrum. In particular, our investigations of a model of the excited state of the heterostructures demonstrate that upon light excitation electrons and holes can be separated onto the TiO₂ surface and the metal oxide nanocluster, which will reduce charge recombination and improve photocatalytic activity. For MgO-modified TiO₂, no significant band gap change is predicted, but for Ga₂O₃-modified TiO₂ we predict a band gap change of up to 0.6 eV, which is sufficient to induce visible light absorption. Comparisons with unmodified TiO₂ and other TiO₂-based photocatalyst structures are presented.

First-principles prediction of new photocatalyst materials with visible-light absorption and improved charge separation: surface modification of rutile TiO₂ with nanoclusters of MgO and Ga₂O₃.

Carbon dioxide reforming of methane is an interesting route for synthesis gas production especially over nano-sized catalysts. The present research deals with catalyst development for dry reforming of methane with the aim of reaching the most stable catalyst. Effect of preparation method, one of the most significant variables, on the properties of the catalysts was taken in to account. The Ni/Al2O3-MgO catalysts were prepared via sol-gel and sequential impregnation methods and characterized with XRD, FESEM, EDAX, BET and FTIR techniques. The reforming reactions were carried out using different feed ratios, gas hourly space velocities (GHSV) and reaction temperatures to identify the influence of operational variables. FESEM images indicate uniform particle size distribution for the sample synthesized with sol-gel method. It has been found that the sol-gel method has the potential to improve catalyst desired properties especially metal surface enrichment resulting in catalytic performance enhancement. The highest yield of products was obtained at 850 degrees C for both of the catalysts. During the 10 h stability test, CH4 and CO2 conversions gained higher values in the case of sol-gel made catalyst compared to impregnated one.

A comparative synthesis and physicochemical characterizations of Ni/Al2O3-MgO nanocatalyst via sequential impregnation and sol-gel methods used for CO2 reforming of methane.

One attractive approach to increase the aqueous solubility and thus the bioavailability of poorly soluble drugs is to formulate them in their amorphous state since amorphous compounds generally exhibit higher apparent solubilities than their crystalline counterparts. In the current work, mesoporous magnesium carbonate was used to stabilise the amorphous state of the model substance ibuprofen. Crystallisation of the drug was completely supressed in the formulation, resulting in both a higher apparent solubility and a three times faster dissolution rate of the drug where the drug release was shown to be diffusion controlled. It was also shown that the formulation is stable for at least three months when stored at 75% relative humidity. The simple synthesis together with a high loading capacity and narrow pore size distribution of the mesoporous magnesium carbonate is foreseen to offer great advantages in formulations of poorly soluble drugs.

Stabilisation of amorphous ibuprofen in Upsalite, a mesoporous magnesium carbonate, as an approach to increasing the aqueous solubility of poorly soluble drugs.

Magnetic nanoparticles have attracted tremendous attention due to their novel properties and their potential applications in magnetic recording, magnetic energy storage and biomedicine.

Chemical Synthesis of Monodisperse Magnetic Nanoparticles

Spectral conversion for solar cells is an emerging concept in the field of photovoltaics, and it has the potential to increase significantly the efficiency of solar cells. Lanthanide ions are ideal candidates for spectral conversion, due to their high luminescence efficiencies and rich energy level structure that allows for great flexibility in the upconversion and downconversion of photons in a wide spectral region (NIR-VIS-UV).

氧化镁

≥99.99% trace metals basis

属性

质量水平

测定

形式

mp

application(s)

SMILES string

InChI

InChI key

相关类别

说明

一般描述

应用

包装

安全信息

储存分类代码

WGK

闪点(F)

闪点(C)

个人防护装备

文件

分析证书

原产地证书 (CofO)

更多文件

Quotes and Ordering

同行评审论文

技术文章和实验方案

技术文章

技术服务

支持

订单

公司

社交媒体

Merck