Study of Transport and Micro-structural properties of Magnesium Di-Boride Strand under react and bend mode and bend and react mode

International Nuclear Information System (INIS)

Kundu, Ananya; Kumar Das, Subrat; Bano, Anees; Pradhan, Subrata

2017-01-01

I-V characterization of commercial multi-filamentary Magnesium Di-Boride (MgB 2 ) wire of diameter 0.83 mm were studied in Cryocooler at self-field I-V characterization system under both react and bend mode and bend and react mode for a range of temperature 6 K - 25 K. This study is of practical technical relevance where the heat treatment of the superconducting wire makes the wire less flexible for winding in magnet and in other applications. In the present work the bending diameter was varied from 40 mm to 20 mm and for each case critical current (I c ) of the strand is measured for above range of temperature. A customized sample holder is fabricated and thermally anchored with the 2 nd cold stage of Cryocooler. It is observed from the measurement that the strand is more susceptible to degradation for react and bend cases. The transport measurement of the strand was accompanied by SEM analyses of bend samples. Also the tensile strength of the raw strands and the heat treated strands were carried out at room temperature in Universal Testing Machine (UTM) to have an estimate about the limiting winding tension value during magnet fabrication. (paper)

Characterization and diffusion model for the titanium boride layers formed on the Ti6Al4V alloy by plasma paste boriding

Energy Technology Data Exchange (ETDEWEB)

Keddam, Mourad, E-mail: keddam@yahoo.fr [Laboratoire de Technologie des Matériaux, Faculté de Génie Mécanique et Génie des Procédés, USTHB, B.P. No. 32, 16111 El-Alia, Bab-Ezzouar, Algiers (Algeria); Taktak, Sukru [Metallurgical and Materials Engineering, Faculty of Technology, Afyon Kocatepe University, ANS Campus, 03200, Afyonkarahisar (Turkey)

2017-03-31

Highlights: • Titanium boride layers were produced by plasma paste boriding on Ti6Al4V at 973–1073 K. • Formation rates of the Ti boride layers have parabolic character at all temperatures. • Boron diffusivities were estimated using a diffusion model including incubation times. • Activation energies of boron in TiB{sub 2} and TiB were 136 and 63 kJ/mol respectively. - Abstract: The present study is focused on the estimation of activation energy of boron in the plasma paste borided Ti6Al4V alloy, which is extensively used in technological applications, using an analytical diffusion model. Titanium boride layers were successfully produced by plasma paste boriding method on the Ti6Al4V alloy in the temperature range of 973–1073 K for a treatment time ranging from 3 to 7 h. The presence of both TiB{sub 2} top-layer and TiB whiskers sub-layer was confirmed by the XRD analysis and SEM observations. The surface hardness of the borided alloy was evaluated using Micro-Knoop indenter. The formation rates of the TiB{sub 2} and TiB layers were found to have a parabolic character at all applied process temperatures. A diffusion model was suggested to estimate the boron diffusivities in TiB{sub 2} and TiB layers under certain assumptions, by considering the effect of boride incubation times. Basing on own experimental data on boriding kinetics, the activation energies of boron in TiB{sub 2} and TiB phases were estimated as 136.24 ± 0.5 and 63.76 ± 0.5 kJ mol{sup −1}, respectively. Finally, the obtained values of boron activation energies for Ti6Al4V alloy were compared with the data available in the literature.

Electrochemical boriding and characterization of AISI D2 tool steel

International Nuclear Information System (INIS)

Sista, V.; Kahvecioglu, O.; Eryilmaz, O.L.; Erdemir, A.; Timur, S.

2011-01-01

D2 is an air-hardening tool steel and due to its high chromium content provides very good protection against wear and oxidation, especially at elevated temperatures. Boriding of D2 steel can further enhance its surface mechanical and tribological properties. Unfortunately, it has been very difficult to achieve a very dense and uniformly thick boride layers on D2 steel using traditional boriding processes. In an attempt to overcome such a deficiency, we explored the suitability and potential usefulness of electrochemical boriding for achieving thick and hard boride layers on this tool steel in a molten borax electrolyte at 850, 900, 950 and 1000 °C for durations ranging from 15 min to 1 h. The microstructural characterization and phase analysis of the resultant boride layers were performed using optical, scanning electron microscopy and X-ray diffraction methods. Our studies have confirmed that a single phase Fe 2 B layer or a composite layer consisting of FeB + Fe 2 B is feasible on the surface of D2 steel depending on the length of boriding time. The boride layers formed after shorter durations (i.e., 15 min) mainly consisted of Fe 2 B phase and was about 30 μm thick. The thickness of the layer formed in 60 min was about 60 μm and composed mainly of FeB and Fe 2 B. The cross sectional micro-hardness values of the boride layers varied between 14 and 22 GPa, depending on the phase composition.

Low-temperature heat capacity of molybdenum borides

International Nuclear Information System (INIS)

Bolgar, A.S.; Klinder, A.V.; Novoseletskaya, L.M.; Turov, V.P.; Klochkov, L.A.; Lyashchenko, A.B.

1988-01-01

Heat capacity of molybdenum borides Mo 2 B, MoB, Mo 2 B 5 is studied for the first time in the 60-300 K range using the adiabatic method. Standard (at 298.15 K) thermodynamic functions (enthalpy, heat capacity, entropy, reduced Gibbs energy) of molybdenum borides are calculated

Fracture toughness of borides formed on boronized ductile iron

International Nuclear Information System (INIS)

Sen, Ugur; Sen, Saduman; Koksal, Sakip; Yilmaz, Fevzi

2005-01-01

In this study, fracture toughness properties of boronized ductile iron were investigated. Boronizing was realized in a salt bath consisting of borax, boric acid and ferro-silicon. Boronizing heat treatment was carried out between 850 and 950 deg. C under the atmospheric pressure for 2-8 h. Borides e.g. FeB, Fe 2 B formed on ductile iron was verified by X-ray diffraction (XRD) analysis, SEM and optical microscope. Experimental results revealed that longer boronizing time resulted in thicker boride layers. Optical microscope cross-sectional observation of borided layers showed dentricular morphology. Both microhardness and fracture toughness of borided surfaces were measured via Vickers indenter. The harnesses of borides formed on the ductile iron were in the range of 1160-2140 HV 0.1 and fracture toughness were in the range of 2.19-4.47 MPa m 1/2 depending on boronizing time and temperature

Synthesis of cobalt boride nanoparticles using radio frequency thermal plasma

International Nuclear Information System (INIS)

Lapitan, Jr. Lorico DS.; Ying Ying Chen; Seesoek Choe; Watanabe, Takayuki

2012-01-01

Nano size cobalt boride particles were synthesized from vapor phase using a 30 kw-4 MHz radio frequency (RF) thermal plasma. Cobalt and boron powder mixtures used as precursors in different composition and feed rate were evaporated immediately in the high temperature plasma and cobalt boride nanoparticles were produced through the quenching process. The x-ray diffractometry (XRD) patterns of cobalt boride nanoparticles prepared from the feed powder ratio of 1:2 and 1:3 for Co: B showed peaks that are associated with the Co 2 B and CoB crystal phases of cobalt boride. The XRD analysis revealed that increasing the powder feed rate results in a higher mass fraction and a larger crystalline diameter of cobalt boride nanoparticles. The images obtained by field emission scanning electron microscopy (FE-SEM) revealed that cobalt boride nanoparticles have a spherical morphology. The crystallite size of the particles estimated with XRD was found to be 18-22 nm. (author)

Evaluation of High Temperature Particle Erosion Resistance of Vanadium-Boride Coating

International Nuclear Information System (INIS)

Lee, E. Y.; Kim, J. H.; Jeong, S. I.; Lee, S. H.; Eum, G. W.

2015-01-01

The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600∼2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipment were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating

Evaluation of High Temperature Particle Erosion Resistance of Vanadium-Boride Coating

Energy Technology Data Exchange (ETDEWEB)

Lee, E. Y.; Kim, J. H.; Jeong, S. I. [Andong National University, Andong (Korea, Republic of); Lee, S. H.; Eum, G. W. [Corporate R and D Institute Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

2015-04-15

The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600∼2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipment were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating.

Boriding with boron carbide base pastes

International Nuclear Information System (INIS)

Aliev, A.A.

1978-01-01

The aim of this paper is to develop an advanced technique of boriding using pastes under the conditions of furnace heating. The research is carried out on flat specimens of 20 and U8 steels pre-annealed in vacuum. B 4 C base pastes were used as saturating media, and the glue prepared by dissolving of nitrocellulose in the mixture of butylacetate and acetone was used as a bond. Measured was the depth of diffusion layers, produced on the 20 and u8 steels after boriding with the pastes under different temperatures and saturation times. The results of metallographic analysis show that borided layers have a specific needle-like structure. The surface of the specimens is clean and free from any paste residues and traces of partial melting

Surface oxidation phenomena of boride coatings grown on iron

International Nuclear Information System (INIS)

Carbucicchio, M.; Palombarini, G.; Sambogna, G.

1992-01-01

Very hard boride coatings are grown on various metals using thermochemical as well as chemical vapour deposition techniques. In this way many surface properties, and in particular the wear resistance, can be considerably improved. Usually, also the corrosion behaviour of the treated components is important. In particular, oxidizing atmospheres are involved in many applications where, therefore, coating-environment interactions can play a relevant role. In a previous work, the early stages of the oxidation of iron borides were studied by treating single phase compacted powders in flowing oxygen at low temperatures (300-450deg C). In the present paper, the attention is addressed to the oxidation of both single phase and polyphase boride coatings thermochemically grown on iron. The single phase boride coatings were constituted by Fe 2 B, while the polyphase coatings were constituted by an inner Fe 2 B layer and an outer FeB-base layer. All the boride layers displayed strong (002) preferred crystallographic orientations. (orig.)

Pulsed nanocrystalline plasma electrolytic boriding as a novel ...

Indian Academy of Sciences (India)

WINTEC

borided CP-Ti, treated by a relatively new method called pulsed plasma electrolytic boriding. The results ... ratio, high stiffness and strength (Donachie 2000; Lutjer- ing and Albrecht ..... both direct current and a.c. techniques. Although the main ...

Pulsed nanocrystalline plasma electrolytic boriding as a novel ...

Indian Academy of Sciences (India)

Potentiodynamic polarization and electrochemical impedance spectroscopy were employed to test borided CP-Ti, treated by a relatively new method called pulsed plasma electrolytic boriding. The results show excellent corrosion resistance for modified CP-Ti. The effect of frequency and duty cycle of pulsed current was ...

Anisotropic elastic and thermal properties of titanium borides by first-principles calculations

Energy Technology Data Exchange (ETDEWEB)

Sun, Liang; Gao, Yimin [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China); Xiao, Bing [Department of Physics and Quantum Theory Group, School of Science and Engineering, Tulane University, New Orleans, LA 70118 (United States); Li, Yefei, E-mail: yefeili@126.com [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China); Wang, Guoliang [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China)

2013-12-05

Highlights: •Elastic properties of titanium borides are calculated by first principles calculation. •Thermodynamical stability of titanium borides is analyzed. •Heat capacity and thermal expansion coefficient for titanium borides are calculated and compared. •Grüneisen parameters of titanium borides are calculated. -- Abstract: The anisotropic elastic and thermal expansions of the titanium borides (TiB{sub 2}, Ti{sub 3}B{sub 4}, TiB{sub P}nma and TiB{sub F}m3{sup ¯}m) are calculated from first-principles using density functional theory. All borides show different anisotropic elastic properties; the bulk, shear and Young’s moduli are consistent with those determined experimentally. The temperature dependence of thermal expansions is mainly caused by the restoration of thermal energy due to phonon excitations at low temperature. When the temperature is higher than 500 K, the volumetric coefficient is increased linearly by increasing temperature. Meanwhile, the heat capacities of titanium borides are obtained based on the knowledge of thermal expansion coefficient and the elasticity, the calculations are in good agreement with the experiments.

Some mechanical properties of borided AISI H13 and 304 steels

International Nuclear Information System (INIS)

Taktak, Sukru

2007-01-01

In the present study, mechanical properties of borides formed on AISI H13 hot work tool and AISI 304 stainless steels have been investigated. Both steels have high chromium content and have a widespread use in the engineering application. Boriding treatment was carried out in slurry salt bath consisting of borax, boric acid, and ferrosilicon at temperature range of 800-950 deg. C for 3, 5, and 7 h. X-ray diffraction analysis of boride layers on the surface of steels revealed various peaks of FeB, Fe 2 B, CrB, and Ni 3 B. Metallographic studies showed that the boride layer has a flat and smooth morphology in the 304 steel while H13 steel was a ragged morphology. The characterization of the boride layer is also carried out by means of the micro-hardness, surface roughness, adhesion, and fracture toughness studies

Bonding and doping of simple icosahedral-boride semiconductors

International Nuclear Information System (INIS)

Emin, David

2004-01-01

A simple model of the bonding and doping of a series of icosahedral-boride insulators is presented. Icosahedral borides contain clusters of boron atoms that occupy the 12 vertices of icosahedra. This particular series of icosahedral borides share both the stoichiometry B 12 X 2 , where X denotes a group V element (P or As), and a common lattice structure. The inter-icosahedral bonding of these icosahedral borides is contrasted with that of B 12 O 2 and with that of α-rhombohedral boron. Knowledge of the various types of inter-icosahedral bonding is used as a basis to address effects of inter-icosahedral atomic substitutions. The inter-icosahedral bonding is maintained when an atom of a group V element is replaced with an atom of a group IV element, thereby producing a p-type dopant. However, changes of inter-icosahedral bonding occur upon replacing an atom of a group V element with an atom of a group VI element or with a vacancy. As a result, these substitutions do not produce effective n-type dopants. Moreover, partial substitution of boron atoms for atoms of group V elements generally renders these materials p-type semiconductors

Plasma boriding of a cobalt–chromium alloy as an interlayer for nanostructured diamond growth

Energy Technology Data Exchange (ETDEWEB)

Johnston, Jamin M.; Jubinsky, Matthew; Catledge, Shane A., E-mail: catledge@uab.edu

2015-02-15

Highlights: • Metal-boride layer creates a compatible surface for NSD deposition. • PECVD boriding on CoCrMo produces robust metal-boride layer. • Deposition temperature comparison shows 750 °C boriding masks surface cobalt. • EDS shows boron diffusion as well as deposition. • Nanoindentation hardness of CoCrMo substantially increases after boriding. - Abstract: Chemical vapor deposited (CVD) diamond coatings can potentially improve the wear resistance of cobalt–chromium medical implant surfaces, but the high cobalt content in these alloys acts as a catalyst to form graphitic carbon. Boriding by high temperature liquid baths and powder packing has been shown to improve CVD diamond compatibility with cobalt alloys. We use the microwave plasma-enhanced (PE) CVD process to deposit interlayers composed primarily of the borides of cobalt and chromium. The use of diborane (B{sub 2}H{sub 6}) in the plasma feedgas allows for the formation of a robust boride interlayer for suppressing graphitic carbon during subsequent CVD of nano-structured diamond (NSD). This metal–boride interlayer is shown to be an effective diffusion barrier against elemental cobalt for improving nucleation and adhesion of NSD coatings on a CoCrMo alloy. Migration of elemental cobalt to the surface of the interlayer is significantly reduced and undetectable on the surface of the subsequently-grown NSD coating. The effects of PECVD boriding are compared for a range of substrate temperatures and deposition times and are evaluated using glancing-angle X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and micro-Raman spectroscopy. Boriding of CoCrMo results in adhered nanostructured diamond coatings with low surface roughness.

Structure, microstructure and residual stresses in borided steels

Czech Academy of Sciences Publication Activity Database

Pala, Z.; Mušálek, Radek; Kyncl, J.; Harcuba, P.; Stráský, J.; Kolařík, K.

2013-01-01

Roč. 20, č. 2 (2013), s. 93-95 ISSN 1211-5894. [Struktura 2013 - Kolokvium Krystalografické společnosti. Češkovice (Blansko), 09.09.2013-13.09.2013] Institutional support: RVO:61389021 Keywords : boriding * surface hardening * iron borides * tooth-shaped microstructure * residual stresses Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://www.xray.cz/ms/bul2013-2/s6.pdf

Boride-based nano-laminates with MAX-phase-like behaviour

International Nuclear Information System (INIS)

Telle, Rainer; Momozawa, Ai; Music, Denis; Schneider, Jochen M.

2006-01-01

MAX-phases being usually composed of transition metals, group A elements and carbon/nitrogen are considered interesting materials for many applications because of their tremendous bulk modulus, 'reversible' plasticity, and machinability. This is mainly due to their unique kind of bonding comprising covalent, ionic as well as metallic bonds providing 'easy' planes of rupture and deformability due to the layered crystal structures. In transition metal boride systems, similar types of bonding are available. In particular the W 2 B 5 -structure type and its stacking variations allow the synthesis of strongly layered crystal structures exhibiting unique delamination phenomena. The paper presents ab initio calculations showing the similarities of bonding between the ternary carbides and the corresponding ternary or quaternary borides. Formation of boride-based nano-laminates from auxiliary liquid phases, from the melt as well as during sintering and precipitation from supersaturated solid solutions will be discussed by means of SEM and TEM studies. The role of impurities weakening the interlayer bonding will be addressed in particular. The pronounced cleavage parallel to the basal plane gives rise for crack deflection and pull-out mechanisms if the laminates are dispersed in brittle matrices such as boron carbide, silicon carbide or other transition metal borides. - Graphical abstract: Some transition metal borides crystallise in a layered structure of alternating stacks of metal and boron atoms giving rise for strongly anisotropic properties. Their preferred cleavage parallel and the deformability perpendicular to the basal plan are similar to the peculiar mechanical behaviour recently described for MAX-phases. Ab initio calculations of the crystal structure prove the weak bonds between the layers for a variety of borides which can be used to reinforce ceramic materials on a nano-scale level

Assessment of polyphase sintered iron-cobalt-iron boride cermets

International Nuclear Information System (INIS)

Nowacki, J.; Pieczonka, T.

2004-01-01

Sintering of iron, cobalt and boron powders has been analysed. As a result iron-iron boride, Fe-Fe 2 B and iron/cobalt boride with a slight admixture of molybdenum, Fe - Co - (FeMoCo) 2 B cermets have been produced. Iron was introduced to the mixture as the Astalloy Mo Hoeganaes grade powder. Elemental amorphous boron powder was used, and formation of borides occurred both during heating and isothermal sintering periods causing dimensional changes of the sintered body. Dilatometry was chosen to control basic phenomena taking place during multiphase sintering of investigated systems. The microstructure and phase constituents of sintered compacts were controlled as well. The cermets produced were substituted to: metallographic tests, X-ray analysis, measurements of hardness and of microhardness, and of wear in the process of sliding dry friction. Cermets are made up of two phases; hard grains of iron - cobalt boride, (FeCo) 2 B (1800 HV) constituting the reinforcement and a relatively soft and plastic eutectic mixture Fe 2 B - Co (400-500 HV) constituting the matrix. (author)

Preparation of boron-rich aluminum boride nanoparticles by RF thermal plasma

Energy Technology Data Exchange (ETDEWEB)

Choi, Sooseok [Inha University, Department of Chemical Engineering and Regional Innovation Center for Environmental Technology of Thermal Plasma (Korea, Republic of); Matsuo, Jiro; Cheng, Yingying [Tokyo Institute of Technology, Department of Environmental Chemistry and Engineering (Japan); Watanabe, Takayuki, E-mail: watanabe@chemenv.titech.ac.jp [Kyushu University, Department of Chemical Engineering (Japan)

2013-08-15

Boron-rich compounds of AlB{sub 12} and AlB{sub 10} nanoparticles were synthesized by a radiofrequency thermal plasma. Aluminum and boron raw powders were evaporated in virtue of high enthalpy of the thermal plasma in upstream region, followed by the formation of aluminum boride nanoparticles in the tail region of plasma flame with rapid quenching. A high production rate of aluminum boride was confirmed by the X-ray diffraction measurement in the case of high input power, high boron content in raw material and helium inner gas. Polyhedral nanoparticles of 20.8 nm in mean size were observed by a transmission electron microscope. In the raw powder mixture of aluminum, titanium, and boron, titanium-boride nanoparticles were synthesized preferentially, because the Gibbs free energy for the boridation of titanium is lower than that of aluminum. Since the nucleation temperature of boron is higher than that of aluminum, the condensation of metal monomers onto boron nuclei results in the formation of boron-rich aluminum boride nanoparticles.

Some physical properties of the higher borides of molybdenum and tungsten

International Nuclear Information System (INIS)

Koval'chenko, M.S.; Bodrova, L.G.; Nemchenko, V.F.; Kolotun, V.F.

1979-01-01

The temperature dependences of the thermal conductivity, the specific electrical resistance, the thermo-e.m.f. and the magnetic susceptibility, together with the variation of magnetic resistance and of Hall constant with the magnetic field strength at liquid nitrogen temperature and at room temperature, for the higher borides Mo 2 B 5 , MoB 4 , W 2 B 5 and WB 4 were studied. Some features of the physical properties of these metallic borides were established. In contrast with the corresponding metals the higher borides are diamagnetic and the Hall constants are negative. The values of the magnetic susceptibility and the Hall constant are larger for the higher borides than for the low borides. As the temperature increased an inversion of the thermo-e.m.f. sign took place and the signs of the thermo-e.m.f. and the Hall constant are different. The values of the magnetic susceptibility of Mo 2 B 5 , MoB 4 and WB 4 were temperature independent. The electronic structure of the compounds studied is discussed briefly. (Auth.)

Preparation of iron boride layers from the gas phase

International Nuclear Information System (INIS)

Marx, G.; Plaenitz, H.; Treffer, G.; Koenig, H.; Altenburger, S.

1980-01-01

Coating of Armco iron, steel-C100W1, and steel-100Cr6 with borides by decomposition of boron tribromide on the surface of the specimens is described. The experiments were carried out in a laboratory apparatus at temperatures between 923 and 1223 K. The dependence of the thickness of the boride layers on time and temperature is presented in graphs

Borides of the group 1 metals of the periodic system

International Nuclear Information System (INIS)

Samsonov, G.V.; Serebryakova, T.I.; Neronov, V.A.

1975-01-01

The borides of alkali metals (lithium, sodium, potassium) and the metals of a copper subgroup (copper, silver, gold) are described. Consideration is given to the crystalline structure and state diagrams of the metal systems within the first group of the Periodic Table with boron. Existence, formation conditions and physico-chemical properties of binary boride phases are characterized. Conclusion is made as to the absence of interaction between boron and silver. Information on the interaction between gold and boron is scanty and conflicting. Methods are described suitable for the production of the borides of the metals within the first group of the Periodic Table [ru

Thermal analysis, phase equilibria, and superconducting properties in magnesium boride and carbon doped magnesium boride

Science.gov (United States)

Bohnenstiehl, Scot David

In this work, the low temperature synthesis of MgB2 from Mg/B and MgH2/B powder mixtures was studied using Differential Scanning Calorimetry (DSC). For the Mg/B powder mixture, two exothermic reaction events were observed and the first reaction event was initiated by the decomposition of Mg(OH)2 on the surface of the magnesium powder. For the MgH 2/B powder mixture, there was an endothermic event at ˜375 °C (the decomposition of MgH2 into H2 and Mg) and an exothermic event ˜600 °C (the reaction of Mg and B). The Kissinger analysis method was used to estimate the apparent activation energy of the Mg and B reaction using DSC data with different furnace ramp rates. The limitations of MgB2 low temperature synthesis led to the development of a high pressure induction furnace that was constructed using a pressure vessel and an induction heating power supply. The purpose was to not only synthesize more homogeneous MgB2 samples, but also to determine whether MgB2 melts congruently or incongruently. A custom implementation of the Smith Thermal Analysis method was developed and tested on aluminum and AlB2, the closest analogue to MgB2. Measurements on MgB2 powder and a high purity Mg/B elemental mixture confirmed that MgB2 melts incongruently and decomposes into a liquid and MgB4 at ˜1445 °C at 10 MPa via peritectic decomposition. Another measurement using a Mg/B elemental mixture with impure boron suggested that ˜0.7 wt% carbon impurity in the boron raised the incongruent melting temperature to ˜1490-1500 °C. Lastly, the solubility limit for carbon in MgB2 was studied by making samples from B4C and Mg at 1530 °C, 1600 °C and 1700 °C in the high pressure furnace. All three samples had three phases: Mg, MgB2C2, and carbon doped MgB2. The MgB 2C2 and carbon doped MgB2 grain size increased with temperature and the 1700 °C sample had needle-like grains for both phases. The presence of the ternary phase, MgB2C2, suggested that the maximum doping limit for carbon in

Preparation of single phase molybdenum boride

International Nuclear Information System (INIS)

Camurlu, Hasan Erdem

2011-01-01

Highlights: → Formation of Mo and a mixture of molybdenum boride phases take place in preparation of molybdenum borides. → It is intricate to prepare single phase molybdenum borides. → Formation of single phase MoB from MoO 3 + B 2 O 3 + Mg mixtures has not been reported previously. → Single phase MoB was successfully prepared through a combination of mechanochemical synthesis and annealing process. - Abstract: The formation of MoB through volume combustion synthesis (VCS), and through mechanochemical synthesis (MCS) followed by annealing has been investigated. MoO 3 , B 2 O 3 and Mg were used as reactants while MgO and NaCl were introduced as diluents. Products were leached in dilute HCl solution and were subjected to X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) examinations. Mo was the major phase component in the VCS products under all the experimental conditions. Mo 2 B, MoB, MoB 2 and Mo 2 B 5 were found as minor phases. Products of MCS contained a mixture of Mo 2 B, MoB, MoB 2 and Mo. After annealing the MCS product at 1400 deg. C for 3 h, single phase α-MoB was obtained.

Standard entropy for borides of non-transition metals, rare-earth metals and actinides

International Nuclear Information System (INIS)

Borovikova, M.S.

1986-01-01

Using as initial data the most reliable values of standard entropy for 10 compounds, the entropies for 40 compounds of non-transition metals, rare-earth metals and actinides have been evaluated by the method of comparative calculation. Taking into account the features of boride structures, two methods, i.e. additive and proportional, have been selected for the entropy calculations. For the range of borides the entropies were calculated from the linear relation of the latter to the number of boron atoms in the boride. For borides of rare-earth metals allowance has been made for magnetic contributions in conformity with the multiplicity of the corresponding ions. Insignificant differences in the electronic contributions to the entropy for borides and metals have been neglected. For dodecaborides only the additive method has been used. This is specified by the most rigid network that provides the same contribution to compound entropy. (orig.)

Investigation of diffusion kinetics of plasma paste borided AISI 8620 ...

Indian Academy of Sciences (India)

Henríquez 2009), plasma boriding (Rodríguez et al 1999) and plasma paste boriding (Gunes et al 2011; Yoon et al ... symmetric geometry with monochromatized radiation (Cu Kα, λ = 0.15418 nm). ..... cate the degree of reliability of the predicted results, when compared with that of the experiments. ... low alloy steels. Surf.

Characterization and wear performance of boride phases over tool steel substrates

Directory of Open Access Journals (Sweden)

Edgar E Vera Cárdenas

2016-02-01

Full Text Available This research work was conducted to characterize boride phases, obtained from the powder-pack process, on AISI H13 and D2 steel substrates, and investigate their tribological behavior. The boriding was developed at a temperature of 1273 K with an exposure time of 8 h. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were conducted on the borided material to characterize the presence of the FeB, Fe2B, and CrB phases and the distribution of heavy elements on the surface of the substrates. The adherence of the boride layers was evaluated, in a qualitative form, through the Daimler-Benz Rockwell-C indentation technique. Sliding wear tests were then performed using a reciprocating wear test machine. All tests were conducted in dry conditions at room temperature. A frequency of 10 Hz and 15-mm sliding distance were used. The applied Hertzian pressure was 2.01 GPa. Scanning electron microscopy was used to observe and analyze the wear mechanisms. Additionally, the variation of the friction coefficient versus the number of cycles was obtained. Experimental results showed that the characteristic wear mechanism for the borided surface was plastic deformation and mild abrasive wear; for unborided substrates, cracking and spalling were observed.

Metal-boride phase formation on tungsten carbide (WC-Co) during microwave plasma chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Johnston, Jamin M.; Catledge, Shane A., E-mail: catledge@uab.edu

2016-02-28

Graphical abstract: - Highlights: • A detailed phase analysis after PECVD boriding shows WCoB, CoB and/or W{sub 2}CoB{sub 2}. • EDS of PECVD borides shows boron diffusion into the carbide grain structure. • Nanoindentation hardness and modulus of borides is 23–27 GPa and 600–780 GPa. • Scratch testing shows hard coating with cracking at 40N and spallation at 70N. - Abstract: Strengthening of cemented tungsten carbide by boriding is used to improve the wear resistance and lifetime of carbide tools; however, many conventional boriding techniques render the bulk carbide too brittle for extreme conditions, such as hard rock drilling. This research explored the variation in metal-boride phase formation during the microwave plasma enhanced chemical vapor deposition process at surface temperatures from 700 to 1100 °C. We showed several well-adhered metal-boride surface layers consisting of WCoB, CoB and/or W{sub 2}CoB{sub 2} with average hardness from 23 to 27 GPa and average elastic modulus of 600–730 GPa. The metal-boride interlayer was shown to be an effective diffusion barrier against elemental cobalt; migration of elemental cobalt to the surface of the interlayer was significantly reduced. A combination of glancing angle X-ray diffraction, electron dispersive spectroscopy, nanoindentation and scratch testing was used to evaluate the surface composition and material properties. An evaluation of the material properties shows that plasma enhanced chemical vapor deposited borides formed at substrate temperatures of 800 °C, 850 °C, 900 °C and 1000 °C strengthen the material by increasing the hardness and elastic modulus of cemented tungsten carbide. Additionally, these boride surface layers may offer potential for adhesion of ultra-hard carbon coatings.

Metal-boride phase formation on tungsten carbide (WC-Co) during microwave plasma chemical vapor deposition

International Nuclear Information System (INIS)

Johnston, Jamin M.; Catledge, Shane A.

2016-01-01

Graphical abstract: - Highlights: • A detailed phase analysis after PECVD boriding shows WCoB, CoB and/or W_2CoB_2. • EDS of PECVD borides shows boron diffusion into the carbide grain structure. • Nanoindentation hardness and modulus of borides is 23–27 GPa and 600–780 GPa. • Scratch testing shows hard coating with cracking at 40N and spallation at 70N. - Abstract: Strengthening of cemented tungsten carbide by boriding is used to improve the wear resistance and lifetime of carbide tools; however, many conventional boriding techniques render the bulk carbide too brittle for extreme conditions, such as hard rock drilling. This research explored the variation in metal-boride phase formation during the microwave plasma enhanced chemical vapor deposition process at surface temperatures from 700 to 1100 °C. We showed several well-adhered metal-boride surface layers consisting of WCoB, CoB and/or W_2CoB_2 with average hardness from 23 to 27 GPa and average elastic modulus of 600–730 GPa. The metal-boride interlayer was shown to be an effective diffusion barrier against elemental cobalt; migration of elemental cobalt to the surface of the interlayer was significantly reduced. A combination of glancing angle X-ray diffraction, electron dispersive spectroscopy, nanoindentation and scratch testing was used to evaluate the surface composition and material properties. An evaluation of the material properties shows that plasma enhanced chemical vapor deposited borides formed at substrate temperatures of 800 °C, 850 °C, 900 °C and 1000 °C strengthen the material by increasing the hardness and elastic modulus of cemented tungsten carbide. Additionally, these boride surface layers may offer potential for adhesion of ultra-hard carbon coatings.

Development and application of high strength ternary boride base cermets

International Nuclear Information System (INIS)

Takagi, Ken-ichi

2006-01-01

Reaction boronizing sintering is a novel strategy to form a ternary boride coexisting with a metal matrix in a cermet during liquid phase sintering. This new sintering technique has successfully developed world first ternary boride base cermets with excellent mechanical properties such as Mo 2 FeB 2 , Mo 2 NiB 2 and WCoB base ones. In these cermets Mo 2 FeB 2 and Mo 2 NiB 2 base ones consist of a tetragonal M 3 B 2 (M: metal)-type complex boride as a hard phase and a transition metal base matrix. The cermets have already been applied to wear resistant applications such as injection molding machine parts, can making tools, and hot copper extruding dies, etc. This paper focuses on the characteristics, effects of the additional elements on the mechanical properties and structure, and practical applications of the ternary boride base cermets. - Graphical abstract: TRS and hardness of Ni-5B-51Mo-17.5Cr and Ni-5B-51Mo-12.5Cr-5V-xMn mass% cermets as functions of Mn content (Fig. 17)

Ni/boride interfaces and environmental embrittlement in Ni-based superalloys: A first-principles study

International Nuclear Information System (INIS)

Sanyal, Suchismita; Waghmare, Umesh V.; Hanlon, Timothy; Hall, Ernest L.

2011-01-01

Highlights: ► Fracture strengths of Ni/boride interfaces through first-principles calculations. ► Fracture strengths of Ni/boride interfaces are higher than Ni/Ni 3 Al and NiΣ5 grain boundaries. ► Ni/boride interfaces have higher resistance to O-embrittlement than Ni/Ni 3 Al and NiΣ5 grain boundaries. ► CrMo-borides are more effective than Cr-borides in resisting O-embrittlement. ► Electronegativity differences between alloying elements correlate with fracture strengths. - Abstract: Motivated by the vital role played by boride precipitates in Ni-based superalloys in improving mechanical properties such as creep rupture strength, fatigue crack growth rates and improved resistance towards environmental embrittlement , we estimate fracture strength of Ni/boride interfaces through determination of their work of separation using first-principles simulations. We find that the fracture strength of Ni/boride interfaces is higher than that of other commonly occurring interfaces in Ni-alloys, such as Ni Σ-5 grain boundaries and coherent Ni/Ni 3 Al interfaces, and is less susceptible to oxygen-induced embrittlement. Our calculations show how the presence of Mo in Ni/M 5 B 3 (M = Cr, Mo) interfaces leads to additional reduction in oxygen-induced embrittlement. Through Electron-Localization-Function based analyses, we identify the electronic origins of effects of alloying elements on fracture strengths of these interfaces and observe that chemical interactions stemming from electronegativity differences between different atomic species are responsible for the trends in calculated strengths. Our findings should be useful towards designing Ni-based alloys with higher interfacial strengths and reduced oxygen-induced embrittlement.

Novel boride base cermets with very high strength

International Nuclear Information System (INIS)

Ken-ichi Takagi; Mari Yonetsu; Yuji Yamasaki

2001-01-01

Mo 2 NiB 2 boride base cermets consist of a Mo 2 NiB 2 type complex boride as a hard phase and a Ni base binder. The addition of Cr and V to the cermets changed the boride structure from orthorhombic to tetragonal and resulted in the improvement of mechanical properties and microstructural refinement. The tetragonal Mo 2 NiB 2 was formed through the orthorhombic Mo 2 NiB 2 by the solid state reaction during sintering and not formed directly from the raw material powders. Ni-4.5B-46.9Mo-12.5V-xMn (wt.%) model cermets with five levels of Mn content from 0 to 10 wt.% were prepared to investigate the effects of Mn on the mechanical properties and microstructure Of Mo 2 NiB 2 base cermets. The transverse rupture strength (TRS) of the cermets depended strongly on the microstructure, which varied significantly with Mn content. The maximum TRS obtained at 2.5 wt.%Mn were 3.5 Gpa with hardness of 87 R A . (author)

Additive-assisted synthesis of boride, carbide, and nitride micro/nanocrystals

International Nuclear Information System (INIS)

Chen, Bo; Yang, Lishan; Heng, Hua; Chen, Jingzhong; Zhang, Linfei; Xu, Liqiang; Qian, Yitai; Yang, Jian

2012-01-01

General and simple methods for the syntheses of borides, carbides and nitrides are highly desirable, since those materials have unique physical properties and promising applications. Here, a series of boride (TiB 2 , ZrB 2 , NbB 2 , CeB 6 , PrB 6 , SmB 6 , EuB 6 , LaB 6 ), carbide (SiC, TiC, NbC, WC) and nitride (TiN, BN, AlN, MgSiN 2 , VN) micro/nanocrystals were prepared from related oxides and amorphous boron/active carbon/NaN 3 with the assistance of metallic Na and elemental S. In-situ temperature monitoring showed that the reaction temperature could increase quickly to ∼850 °C, once the autoclave was heated to 100 °C. Such a rapid temperature increase was attributed to the intense exothermic reaction between Na and S, which assisted the formation of borides, carbides and nitrides. The as-obtained products were characterized by XRD, SEM, TEM, and HRTEM techniques. Results in this report will greatly benefit the future extension of this approach to other compounds. - Graphical abstract: An additive-assisted approach is successfully developed for the syntheses of borides, carbides and nitrides micro/nanocrystals with the assistance of the exothermic reaction between Na and S. Highlights: ► An additive-assisted synthesis strategy is developed for a number of borides, carbides and nitrides. ► The reaction mechanism is demonstrated by the case of SiC nanowires. ► The formation of SiC nanowires is initiated by the exothermic reaction of Na and S.

Laser borided composite layer produced on austenitic 316L steel

Directory of Open Access Journals (Sweden)

Mikołajczak Daria

2016-12-01

Full Text Available Abstract Austenitic 316L steel is well-known for its good resistance to corrosion and oxidation. Therefore, this material is often used wherever corrosive media or high temperatures are to be expected. The main drawback of this material is very low hardness and low resistance to mechanical wear. In this study, the laser boriding was used in order to improve the wear behavior of this material. As a consequence, a composite surface layer was produced. The microstructure of laser-borided steel was characterized by only two zones: re-melted zone and base material. In the re-melted zone, a composite microstructure, consisting of hard ceramic phases (borides and a soft austenitic matrix, was observed. A significant increase in hardness and wear resistance of such a layer was obtained.

Improving the corrosion resistance of AZ91D magnesium alloy through reinforcement with titanium carbides and borides

OpenAIRE

Gobara, Mohamed; Shamekh, Mohamed; Akid, Robert

2015-01-01

A composite consisting of magnesium matrix reinforced with a network of TiC–Ti2AlC–TiB2 particulates has been fabricated using a practical in-situ reactive infiltration technique. The microstructural and phase composition of the magnesium matrix composite (R-Mg) was investigated using SEM/EDS and XRD. The analyses revealed the complete formation of TiC, Ti2AlC and TiB2 particles in the magnesium matrix. Comparative compression tests of R-Mg and AZ91D alloy showed that the reinforcing particle...

Swelling and fracturing of borides under neutron irradiation

International Nuclear Information System (INIS)

Krainy, A.G.; Ogorodnikov, V.V.; Grinik, E.U.; Chirko, L.I.; Shinakov, A.A.

1994-01-01

The neutron irradiation of high temperature borides, which are included in boron-containing reactor materials, results in high internal stresses, leading to considerable swelling and micro- and macro-fracturing. Experimental results over a large range of temperature and fluences, show a change of damage mechanism for borides within 400-530 C: the macro-cracking with formation of annular and radial cracks is observed below this temperature zone. The accumulation of micro-fractures and the process of gas swelling take place at irradiation temperatures above 530 C. The effect of the high internal stresses is compared to external pressure. 12 refs., 4 figs

Tetragonal ternary borides: superconductivity, ferromagnetism and the role of scandium

International Nuclear Information System (INIS)

Matthias, B.T.; Patel, C.K.N.; Barz, H.; Corenzwit, E.; Vandenberg, J.M.

1978-01-01

The authors report and discuss two discoveries made while studying the condensation phenomena of ternary rhodium borides, MRh 4 B 4 . M is generally a trivalent transition metal, usually a rare earth element RE. An exception is scandium which by itself does not form an isomorphous boride, but in combination with many other elements will do just that. A suprising correlation between ferromagnetic and superconducting transition temperatures has been found. (Auth.)

Characterisation of Wear Resistant Boride Layers on a Tool Steel by Activity Controlled Pack Boronising

DEFF Research Database (Denmark)

Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Somers, Marcel A. J.

2015-01-01

The present work addresses the production and characterisation of iron boride layers by pack boronising of a Vanadis 6 tool steel. The boride layers were produced at 900°C for 2h using different pack compositions in order to obtain a single-phase boride layer. The layers were characterized...... by electron microscopy, glow discharge optical emission spectroscopy, X-ray diffraction, Vickers hardness tests and wear testing with a pin-on-disc tribometer. It was found that the type of boride phases (FeB and/or Fe2B) present in the treated layer can be controlled by changing the boron activity...... by pack boronising for all conditions as compared to the heat treated tool steel....

Production and properties of boride powders

International Nuclear Information System (INIS)

Klinskaya, N.A.; Koroleva, E.B.; Petrunichev, V.A.

1990-01-01

Results of plasma metallization of boride powders 40-80 μ diam. are presented. Peculiarities of changes of granulometric powder composition and of metallic cover on refractory cores were investigated. There are shown size- and compositional cores effects on metallization level of poders and on cover structure

Platinum boride nanowires: Synthesis and characterization

International Nuclear Information System (INIS)

Ding Zhanhui; Qiu Lixia; Zhang Jian; Yao Bin; Cui Tian; Guan Weiming; Zheng Weitao; Wang Wenquan; Zhao Xudong; Liu Xiaoyang

2012-01-01

Highlights: ► Platinum boride nanowires have been synthesized via the direct current arc discharge method. ► XRD, TEM and SAED indicate that the nanowires are single-crystal PtB. ► Two broad photoluminescence emission peaks at about 586 nm and 626 nm have been observed in the PL spectroscopy of PtB nanowires. - Abstract: Platinum boride (PtB) nanowires have been successfully fabricated with direct current arc discharge method using a milled mixture of platinum (Pt) and boron nitride (BN) powders. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the compositions, morphology, and structures of the samples. The results show that PtB nanowires are 30–50 nm thick and 20–30 μm long. TEM and selected area electron diffraction (SAED) patterns identify that the PtB nanowires are single-crystalline in nature. A growth mechanism based on vapor–liquid–solid (VLS) process is proposed for the formation of nanowires.

Corrosion behavior of boride layers evaluated by the EIS technique

Energy Technology Data Exchange (ETDEWEB)

Campos, I. [Instituto Politecnico Nacional. SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico)], E-mail: icampos@ipn.mx; Palomar-Pardave, M. [Universidad Autonoma Metropolitana-Azcapotzalco, Materials Department, Avenue San Pablo 180 Col. Reynosa Tamaulipas, Mexico D.F. 02200 (Mexico); Amador, A. [Tecnologico de Monterrey, Campus Ciudad de Mexico, Calle del Puente 222 Col. Ejidos de Huipulco, Mexico D.F. 14380 (Mexico); VillaVelazquez, C. [Instituto Politecnico Nacional. SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico); Hadad, J. [Tecnologico de Monterrey, Campus Ciudad de Mexico, Calle del Puente 222 Col. Ejidos de Huipulco, Mexico D.F. 14380 (Mexico)

2007-09-30

The corrosion behavior of boride layers at the AISI 304 steel surface is evaluated in the present study. Electrochemical impedance spectroscopy (EIS) technique was used for the evaluation of the polarization resistance at the steel surface, with the aid of AUTOLAB potentiostat. Samples were treated with boron paste thickness of 4 and 5 mm, in the range of temperatures 1123 {<=} T {<=} 1273 K and exposed time of 4 and 6 h. The electrochemical technique employed 10 mV AC with a frequency scan range from 8 kHz to 3 mHz in deaerated 0.1 M NaCl solution. Nyquist diagrams show that the highest values of corrosion resistance are present in the samples borided at the temperature of 1273 K, with treatment time of 4 h and 4 mm of boron paste thickness. The values of corrosion resistance on borided steels are compared with the porosity exhibited in the layers.

Improving the corrosion resistance of AZ91D magnesium alloy through reinforcement with titanium carbides and borides

Directory of Open Access Journals (Sweden)

Mohamed Gobara

2015-06-01

Full Text Available A composite consisting of magnesium matrix reinforced with a network of TiC–Ti2AlC–TiB2 particulates has been fabricated using a practical in-situ reactive infiltration technique. The microstructural and phase composition of the magnesium matrix composite (R-Mg was investigated using SEM/EDS and XRD. The analyses revealed the complete formation of TiC, Ti2AlC and TiB2 particles in the magnesium matrix. Comparative compression tests of R-Mg and AZ91D alloy showed that the reinforcing particles improve the mechanical properties of Mg alloy. EIS and potentiodynamic polarization results indicated that the reinforcing particles significantly improve the corrosion resistance of the reinforced alloy in 3.5% NaCl solution.

Hard Surface Layers by Pack Boriding and Gaseous Thermo-Reactive Deposition and Diffusion Treatments

DEFF Research Database (Denmark)

Christiansen, Thomas Lundin; Bottoli, Federico; Dahl, Kristian Vinter

2017-01-01

) layers with hardnesses up to 1800 HV. Titanizing of ARNE tool steel results in a surface layer consisting of TiC with a hardness of approximately 4000 HV. Duplex treatments, where boriding is combined with subsequent (TRD) titanizing, result in formation of hard TiB2 on top of a thick layer of Fe......Thermo-reactive deposition and diffusion (TRD) and boriding are thermochemical processes that result in very high surface hardness by conversion of the surface into carbides/nitrides and borides, respectively. These treatments offer significant advantages in terms of hardness, adhesion, tribo...... subjected to TRD (chromizing and titanizing) and boriding treatments. For the steels with low carbon content, chromizing results in surface alloying with chromium, i.e., formation of a (soft) “stainless” surface zone. Steels containing higher levels of carbon form chromium carbide (viz. Cr23C6, Cr7C3...

Study of microcracks morphology produced by Vickers indentation on AISI 1045 borided steels

International Nuclear Information System (INIS)

Campos, I.; Ramirez, G.; VillaVelazquez, C.; Figueroa, U.; Rodriguez, G.

2008-01-01

In this work, we analyzed the roughness morphology of indentation microcracks produced by the Vickers microindentation in the iron boride Fe 2 B. Using the paste boriding process, the boride layers were formed at the surface of AISI 1045 steels. The diffusion processes were carried out with 5 mm of boron paste thickness over the substrate surface at three different temperatures (1193, 1223 and 1273 K) with two different time exposures. The indentations in each Fe 2 B layer were made using a constant load of 200 g at four different distances from the surface. The fracture behavior of the Fe 2 B borided phase is found to be brittle in nature. The profiles of microcracks formed at the corners of the indentations were obtained using the scanning electronic microscopy and were analyzed within the framework of fractal geometry. We found that all indentation microcracks display a self-affine invariance characterized by the same roughness (Hurst) exponent H = 0.8 ± 0.1. The effect of the self-affine roughness of indentation microcracks on the measured fracture toughness is discussed within the framework of the mechanics of self-affine cracks. It is pointed out that the arrest of indentation microcracks is controlled by the fractal fracture toughness, which for the Fe 2 B borided phase is found to be K fc = 0.42 ± 0.02 MPa m 0.75 at all distances from the surface

Metal Immiscibility Route to Synthesis of Ultrathin Carbides, Borides, and Nitrides.

Science.gov (United States)

Wang, Zixing; Kochat, Vidya; Pandey, Prafull; Kashyap, Sanjay; Chattopadhyay, Soham; Samanta, Atanu; Sarkar, Suman; Manimunda, Praveena; Zhang, Xiang; Asif, Syed; Singh, Abhisek K; Chattopadhyay, Kamanio; Tiwary, Chandra Sekhar; Ajayan, Pulickel M

2017-08-01

Ultrathin ceramic coatings are of high interest as protective coatings from aviation to biomedical applications. Here, a generic approach of making scalable ultrathin transition metal-carbide/boride/nitride using immiscibility of two metals is demonstrated. Ultrathin tantalum carbide, nitride, and boride are grown using chemical vapor deposition by heating a tantalum-copper bilayer with corresponding precursor (C 2 H 2 , B powder, and NH 3 ). The ultrathin crystals are found on the copper surface (opposite of the metal-metal junction). A detailed microscopy analysis followed by density functional theory based calculation demonstrates the migration mechanism, where Ta atoms prefer to stay in clusters in the Cu matrix. These ultrathin materials have good interface attachment with Cu, improving the scratch resistance and oxidation resistance of Cu. This metal-metal immiscibility system can be extended to other metals to synthesize metal carbide, boride, and nitride coatings. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wear behavior of tempered and borided tool steels under various conditions

International Nuclear Information System (INIS)

Al-Haidary, T. J.; Faleh, M. N.

2000-01-01

. Tool steel 61CrV5, 50 NiCr13 and X1000Cr MoV51 were used in the first stage of this investigation. They have been treated as follows: boriding, boriding and tempering and hardening and tempering. The wear tests were conducted under fixed conditions (150 N/mm 2 , 0.48m/sec) with and without lubricant. The wear rate and coefficient of friction of 61Cr Si V5 steel have been studied in the second stage hoping to find the influence of working conditions on these parameters and then to compare these results with the case of hardening and tempering which is the usual case in the actual working field. The study gives a good indication about the improvement achieved in boriding and tempering cases (∼ 30%) as compared with hardening tempering cases in dry sliding conditions -∼5% with lubricating ones. (authors). 13 refs., 19 figs., 1 table

Kinetics of boride layers formed on the surface of AISI 4140 steel

International Nuclear Information System (INIS)

Sen, S.; Sen, U.; Bindal, C.

2004-01-01

The present study reports on boride layer growth kinetics of borided AISI 4140 steel. Steels were boronized in molten borax, boric acid and ferro-silicon bath at 1123 K 1173 K and 1223 K for 2, 4, 6 and 8 hours. Boride layer thickness ranged from 38.4 to 225 μm. Layer growth kinetics were analysed by measuring the extent of penetration of FeB and Fe 2 B sublayers as a function of boronizing time and temperature in the range of 1123-1223 K. The depth of the tips of the most deeply penetrated FeB and Fe 2 B needles are taken as measures for diffusion in the fast directions. The kinetics of the reaction, K=K 0 exp(-Q/RT) have also been determined by varying the boriding temperature and time. The results showed that K increase with boronizing temperature. Activation energy (Q) for present study was determined as 215 kj.mol -1 . The diffusion coefficient (K) ranged from 3 x 10 -9 cm 2 s -1 to 2 x 10 -8 cm 2 s -1 . Also temperature-dependent constant (K 0 ) at temperatures 1123 K, 1173 K and 1223 K was 179.4 cm 2 s -1 . (orig.)

Superconductivity in borides and carbides

International Nuclear Information System (INIS)

Muranaka, Takahiro

2007-01-01

It was thought that intermetallic superconductors do not exhibit superconductivity at temperatures over 30 K because of the Bardeen-Cooper-Schrieffer (BCS) limit; therefore, researchers have been interested in high-T c cuprates. Our group discovered high-T c superconductivity in MgB 2 at 39 K in 2001. This discovery has initiated a substantial interest in the potential of high-T c superconductivity in intermetallic compounds that include 'light' elements (borides, carbides, etc.). (author)

The effect of boriding on wear resistance of cold work tool steel

International Nuclear Information System (INIS)

Anzawa, Y; Koyama, S; Shohji, I

2017-01-01

Recently, boriding has attracted extensive attention as surface stiffening processing of plain steel. In this research, the influence of processing time on the formation layer of cold work tool steel (KD11MAX) by Al added fused salt bath was examined. In addition, in order to improve the abrasion resistance of KD11MAX, the effect of the treatment of boronization on the formation layer has been investigated. Boriding were performed in molten borax which contained about 10 mass% Al at processing time of 1.8 ∼ 7.2 ks (processing temperature of 1303 K). As a result of the examination, the hardness of the boriding layer becomes about 1900 HV when the processing time of 3.6 ks. Also the abrasion resistance has improved remarkably. Furthermore, it was revealed that the formation layer was boronized iron from the Vickers hardness and analysis of the X-ray diffraction measurement. (paper)

Thermodynamic properties of molybdenum borides at temperatures above 300 K

International Nuclear Information System (INIS)

Bolgar, A.S.; Blinder, A.V.; Serbova, M.I.

1990-01-01

Enthalpy of Mo 2 B, MoB, Mo 2 B 5 borides within the range of temperatures above 300 K has been experimentally studied. Parameters of temperature dependences of enthalpy, heat capacity, entropy and the reduced Gibbs energy of the studied substances are calculated within a wide range. It is stated that high-temperature heat capacity of the studied borides can be presented as a sum of the electron component, a harmonic part of the lattice component and a contribution caused by anharmonic oscillations of lattice atoms. Values of coefficients of isothermal compressibility of Mo 2 , MoB, Mo 2 B 5 within the high temperature range are estimated

Kinetics of boride layers formed on the surface of AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Sen, S.; Sen, U. [Sakarya Univ., Dept. of Metal Education, Sakarya (Turkey); Bindal, C. [Sakarya Univ., Dept. of Materials and Metallurgy, Sakarya (Turkey)

2004-07-01

The present study reports on boride layer growth kinetics of borided AISI 4140 steel. Steels were boronized in molten borax, boric acid and ferro-silicon bath at 1123 K 1173 K and 1223 K for 2, 4, 6 and 8 hours. Boride layer thickness ranged from 38.4 to 225 {mu}m. Layer growth kinetics were analysed by measuring the extent of penetration of FeB and Fe{sub 2}B sublayers as a function of boronizing time and temperature in the range of 1123-1223 K. The depth of the tips of the most deeply penetrated FeB and Fe{sub 2}B needles are taken as measures for diffusion in the fast directions. The kinetics of the reaction, K=K{sub 0} exp(-Q/RT) have also been determined by varying the boriding temperature and time. The results showed that K increase with boronizing temperature. Activation energy (Q) for present study was determined as 215 kj.mol{sup -1}. The diffusion coefficient (K) ranged from 3 x 10{sup -9} cm{sup 2}s{sup -1} to 2 x 10{sup -8} cm{sup 2}s{sup -1}. Also temperature-dependent constant (K{sub 0}) at temperatures 1123 K, 1173 K and 1223 K was 179.4 cm{sup 2}s{sup -1}. (orig.)

Transition metal borides. Synthesis, characterization and superconducting properties

International Nuclear Information System (INIS)

Kayhan, Mehmet

2013-01-01

A systematic study was done on the synthesis and superconducting properties of metal rich transition metal borides. Five different binary systems were investigated including the boride systems of niobium, tantalum, molybdenum, tungsten and rhenium. High temperature solid state methods were used in order to synthesize samples of different transition metal borides of the composition M 2 B, MB, M 3 B 2 , MB 2 , and M 2 B 4 . The reactions were carried out in three different furnaces with different sample containers: the electric arc (copper crucible), the high frequency induction furnace (boron nitride, tantalum or glassy carbon crucibles), and the conventional tube furnace (sealed evacuated quartz ampoules). The products obtained were characterized with X-ray powder diffractometry, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Phase analyses and crystal structure refinements using the Rietveld method and based on structure models known from literature were performed. A neutron diffraction measurement was done for W 2 B 4 to allow for a complete crystal structure determination, because of the presence of a heavy element like tungsten and a light element like boron that made it difficult to determine the accurate determination of the boron atom positions and occupancies from X-ray data. A new structure model for W 2 B 4 was proposed. Magnetic measurements in a SQUID magnetometer down to temperatures as low as 1.8 K were performed to several of the products in order to see if the transition metal borides become superconducting at low temperatures, and the results were compared with data from literature. Superconducting properties were found for the following compounds: NbB 2 (T C = 3.5 K), β-MoB (T C = 2.4 K), β-WB (T C = 2.0 K), α-WB (T C = 4.3 K), W 2 B 4 (T C = 5.4 K), Re 7 B 3 (T C = 2.4 K). A relationship between the superconducting properties and the compositional and structural features was discussed for metal diborides. Also it was

Hardness optimization of boride diffusion layer on Astm F-75 alloy using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Arguelles O, J. L.; Corona R, M. A. [Universidad Autonoma de San Luis Potosi, Doctorado Institucional en Ingenieria y Ciencia de Materiales, San Luis Potosi 78000, SLP (Mexico); Marquez H, A.; Saldana R, A. L.; Saldana R, A. [Universidad de Guanajuato, Ingenieria Mecanica Agricola DICIVA, Irapuato, Guanajuato 36500 (Mexico); Moreno P, J., E-mail: amarquez@ugto.mx [Universidad de Guanajuato, Departamento de Minas, Metalurgia y Geologia, Ex-Hacienda San Matias s/n, Guanajuato, Guanajuato 36020 (Mexico)

2017-11-01

In this study, the Response Surface Methodology (Rsm) and Central Composite Design (Ccd) were used to optimize the hardness of boride diffusion layer on Astm F-75 alloy (also called Haynes alloy). A boronizing thermochemical treatment was carried out at different temperatures and for different time periods. Hardness tests were conducted. The boride diffusion layer was verified by the X-ray diffraction (XRD) analysis indicating the formation of Co B, Co{sub 2}B, Cr B and Mo{sub 2}B phases. An optimal hardness of 3139.7 Hv was obtained for the samples subjected to the boriding process for a duration of 6.86 h at 802.4 degrees Celsius. (Author)

Growth kinetics of borided layers: Artificial neural network and least square approaches

Science.gov (United States)

Campos, I.; Islas, M.; Ramírez, G.; VillaVelázquez, C.; Mota, C.

2007-05-01

The present study evaluates the growth kinetics of the boride layer Fe 2B in AISI 1045 steel, by means of neural networks and the least square techniques. The Fe 2B phase was formed at the material surface using the paste boriding process. The surface boron potential was modified considering different boron paste thicknesses, with exposure times of 2, 4 and 6 h, and treatment temperatures of 1193, 1223 and 1273 K. The neural network and the least square models were set by the layer thickness of Fe 2B phase, and assuming that the growth of the boride layer follows a parabolic law. The reliability of the techniques used is compared with a set of experiments at a temperature of 1223 K with 5 h of treatment time and boron potentials of 2, 3, 4 and 5 mm. The results of the Fe 2B layer thicknesses show a mean error of 5.31% for the neural network and 3.42% for the least square method.

Transition metal borides. Synthesis, characterization and superconducting properties

Energy Technology Data Exchange (ETDEWEB)

Kayhan, Mehmet

2013-07-12

A systematic study was done on the synthesis and superconducting properties of metal rich transition metal borides. Five different binary systems were investigated including the boride systems of niobium, tantalum, molybdenum, tungsten and rhenium. High temperature solid state methods were used in order to synthesize samples of different transition metal borides of the composition M{sub 2}B, MB, M{sub 3}B{sub 2}, MB{sub 2}, and M{sub 2}B{sub 4}. The reactions were carried out in three different furnaces with different sample containers: the electric arc (copper crucible), the high frequency induction furnace (boron nitride, tantalum or glassy carbon crucibles), and the conventional tube furnace (sealed evacuated quartz ampoules). The products obtained were characterized with X-ray powder diffractometry, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Phase analyses and crystal structure refinements using the Rietveld method and based on structure models known from literature were performed. A neutron diffraction measurement was done for W{sub 2}B{sub 4} to allow for a complete crystal structure determination, because of the presence of a heavy element like tungsten and a light element like boron that made it difficult to determine the accurate determination of the boron atom positions and occupancies from X-ray data. A new structure model for W{sub 2}B{sub 4} was proposed. Magnetic measurements in a SQUID magnetometer down to temperatures as low as 1.8 K were performed to several of the products in order to see if the transition metal borides become superconducting at low temperatures, and the results were compared with data from literature. Superconducting properties were found for the following compounds: NbB{sub 2} (T{sub C} = 3.5 K), β-MoB (T{sub C} = 2.4 K), β-WB (T{sub C} = 2.0 K), α-WB (T{sub C} = 4.3 K), W{sub 2}B{sub 4} (T{sub C} = 5.4 K), Re{sub 7}B{sub 3} (T{sub C} = 2.4 K). A relationship between the superconducting properties

Study of transport and micro-structural properties of magnesium di-boride strand under react and bend mode and bend and react mode

International Nuclear Information System (INIS)

Kundu, Ananya; Das, Subrat Kumar; Bano, Anees; Pradhan, Subrata

2015-01-01

I-V characterization of commercial multi-filamentary Magnesium Di-Boride (MgB 2 ) wire of diameter 0.83 mm were studied in cryocooler based self-field characterization system under both react and bent mode and bent and react mode for a range of temperature 6 K - 25 K. This study is of practical technical relevance where the heat treatment of the superconducting wire makes the sample less flexible for winding in magnet and in other applications. There are limited reported data, available on degradation of MgB 2 wire with bending induced strain in react and wind and wind and react method. In the present work the bending diameter were varied from 80 mm to 20 mm in the interval of 10 mm change of bending diameter and for each case critical current (Ic) of the strand is measured for the above range of temperature. An ETP copper made customized sample holder for mounting the MgB 2 strand was fabricated and is thermally anchored to the cooling stage of the cryocooler. It is seen from the experimental data that in react and bent mode the critical current degrades from 105 A to 87 A corresponding to bending diameter of 80 mm and 20 mm respectively. The corresponding bending strain was analytically estimated and compared with the simulation result. It is also observed that in react and bent mode, the degradation of the transport property of the strand is less as compared to react and bent mode. For bent and react mode in the same sample, the critical current (Ic) was measured to be ∼145 A at 15 K for bending diameter of 20 mm. Apart from studying the bending induced strain on MgB 2 strand, the tensile test of the strand at RT was carried out. The electrical characterizations of the samples were accompanied by the microstructure analyses of the bent strand to examine the bending induced degradation in the grain structure of the strand. All these experimental findings are expected to be used as input to fabricate prototype MgB 2 based magnet. (author)

Preparation of molybdenum borides by combustion synthesis involving solid-phase displacement reactions

International Nuclear Information System (INIS)

Yeh, C.L.; Hsu, W.S.

2008-01-01

Preparation of molybdenum borides of five different phases in the Mo-B binary system (including Mo 2 B, MoB, MoB 2 , Mo 2 B 5 , and MoB 4 ) was performed by self-propagating high-temperature synthesis (SHS) with two kinds of the reactant samples. When elemental powder compacts with an exact stoichiometry corresponding to the boride phase were employed, self-sustaining reaction was only achieved in the sample with Mo:B = 1:1 and nearly single-phase MoB was yielded. Therefore, the other four boride compounds were prepared from the reactant compacts composed of MoO 3 , Mo, and B powders, within which the displacement reaction of MoO 3 with boron was involved in combustion synthesis. Experimental evidence shows that the extent of displacement reaction in the overall reaction has a significant impact on sustainability of the synthesis reaction, combustion temperature, reaction front velocity, and composition of the end product. An increase in the solid-phase displacement reaction taking place during the SHS process contributes more heat flux to the synthesis reaction, thus resulting in the increase of combustion temperature and enhancement of the reaction front velocity. Based upon the XRD analysis, formation of Mo 2 B, MoB 2 , and Mo 2 B 5 as the dominant boride phase in the end product was successful through the SHS reaction with powder compacts under appropriate stoichiometries between MoO 3 , Mo, and B. However, a poor conversion was observed in the synthesis of MoB 4 . The powder compact prepared for the production of MoB 4 yielded mostly Mo 2 B 5

Synthesis of borides in molybdenum implanted by B+ ions under thermal and electron annealing

International Nuclear Information System (INIS)

Kazdaev, Kh.R.; Akchulakov, M.T.; Bayadilov, E.M.; Ehngel'ko, V.I.; Lazarenko, A.V.; Chebukov, E.S.

1989-01-01

The possibility of formation of borides in the near surface layers of monocrystalline molybdenum implanted by boron ions at 35 keV energy under thermal and pulsed electron annealing by an electon beam at 140 keV energy is investigated. It is found that implantation of boron ions into molybdenum with subsequent thermal annealing permits to produce both molybdenum monoboride (α-MoB) and boride (γ-Mo 2 B) with rather different formation mechanisms. Formation of the α-MoB phase occurs with the temperature elevation from the centers appeared during implantation, while the γ-Mo 2 B phase appears only on heating the implanted layers up to definite temperature as a result of the phase transformation of the solid solution into a chemical compound. Pulsed electron annealing instead of thermal annealing results mainly in formation of molybdenum boride (γ-Mo 2 B), the state of structure is determined by the degree of heating of implanted layers and their durable stay at temperatures exceeding the threshold values

Elevated temperature tensile properties of borated 304 stainless steel: Effect of boride dispersion on strength and ductility

International Nuclear Information System (INIS)

Stephens, J.J.; Sorenson, K.B.; McConnell, P.

1991-01-01

This paper has documented the increase in strain to fracture and yield strength obtained with Grade A versions of types 304B5 and 304B7 relative to their respective Grade B, counterparts. The apparent microstructural reason for these property increases is the finer dispersion of boride in the Grade A material, obtained by means of a Powder Metallurgy process, relative to the conventional Grade B material which is produced using an Ingot Metallurgy process. The area size distribution of borides can be well approximated using a log-normal distribution, with the largest boride particles in the Grade B material having areas in the range of 450--600 μm 2 . By comparison, the largest boride particles in the Grade A material have areas nearly an order of magnitude smaller than the largest particles in their Grade B counterparts. A Section III ASME B ampersand PV code case inquiry has been initiated for non-welded versions of 304B4A, 3045A and 3046A ,material

Micro-Abrasion Wear Resistance of Borided 316L Stainless Steel and AISI 1018 Steel

Science.gov (United States)

Reséndiz-Calderon, C. D.; Rodríguez-Castro, G. A.; Meneses-Amador, A.; Campos-Silva, I. E.; Andraca-Adame, J.; Palomar-Pardavé, M. E.; Gallardo-Hernández, E. A.

2017-11-01

The 316L stainless steel has high corrosion resistance but low tribological performance. In different industrial sectors (biomedical, chemical, petrochemical, and nuclear engineering), improvement upon wear resistance of 316L stainless steel components using accessible and inexpensive methods is critical. The AISI 1018 steel is widely used in industry, but its tribological performance is not the best among steels. Therefore, in this study the behavior of the borided 316L stainless steel and 1018 steel is evaluated under micro-abrasion wear. The boriding was carried out at 1223 K over 6 h of exposure time, resulting in a biphase layer composed of FeB/Fe2B phases. In order to evaluate Fe2B phase with no influence from FeB phase, AISI 1018 steel samples were borided at 1273 K for over 20 min and then diffusion annealed at 1273 K over 2 h to obtain a Fe2B mono-phase layer. Micro-abrasion wear resistance was evaluated by a commercial micro-abrasion testing rig using a mix of F-1200 SiC particles with deionized water as abrasive slurry. The obtained wear rates for FeB and Fe2B phases and for the 316L stainless steel were compared. Wear resistance of 316L stainless steel increases after boriding. The wear mechanisms for both phases and for the stainless steel were identified. Also, transient conditions for rolling and grooving abrasion were determined for the FeB and Fe2B phases.

Subminiature eddy current transducers for studying boride coatings

Science.gov (United States)

Dmitriev, S. F.; Ishkov, A. V.; Malikov, V. N.; Sagalakov, A. M.

2016-07-01

Strengthening of parts and units of machines, increased reliability and longer service life is an important task of modern mechanical engineering. The main objects of study in the work were selected steel 65G and 50HGA, wear-resistant boride coatings ternary system Fe-B-Fe n B which were investigated by scanning electron microscopy and eddy-current nondestructive methods.

Hardness of carbides, nitrides, and borides

International Nuclear Information System (INIS)

Schroeter, W.

1981-01-01

Intermetallic compounds of metals with non-metals such as C, N, and B show different hardness. Wagner's interaction parameter characterizes manner and extent of the interaction between the atoms of the substance dissolved and the additional elements in metallic mixed phases. An attempt has been made to correlate the hardness of carbides, nitrides, and borides (data taken from literature) with certain interaction parameters and associated thermodynamic quantities (ΔH, ΔG). For some metals of periods 4, 5, and 6 corresponding relations were found between microhardness, interaction parameters, heat of formation, and atomic number

Comparative NMR investigation of the Re-based borides

Science.gov (United States)

Lue, C. S.; Tao, Y. F.; Su, T. H.

2008-07-01

We report a systematic study of the rhenium-based borides, ReB2 , Re7B3 , and Re3B , by means of the B11 nuclear magnetic resonance (NMR) spectroscopy. While Re7B3 and Re3B are superconductors, ReB2 exhibits no superconducting signature but is of current interest due to its superhard mechanical property. Since the major focus of this investigation is their electronic characteristics in the normal states, we performed the measurements at temperatures between 77 and 295 K. For Re7B3 and Re3B , s -character electrons were found to be responsible for the observed B11 NMR Knight shift and spin-lattice relaxation rate (1/T1) . From T1 analysis, we thus deduce the partial Bs Fermi-level density of states (DOS) of both borides. On the other hand, the relaxation rate of ReB2 is mainly associated with p electrons, similar to the cases of OsB2 and RuB2 . In addition, the extracted B2p Fermi-level DOS is in good agreement with the theoretical prediction from band-structure calculations.

Wear resistance of laser-deposited boride reinforced Ti-Nb-Zr-Ta alloy composites for orthopedic implants

International Nuclear Information System (INIS)

Samuel, Sonia; Nag, Soumya; Scharf, Thomas W.; Banerjee, Rajarshi

2008-01-01

The inherently poor wear resistance of titanium alloys limits their application as femoral heads in femoral (hip) implants. Reinforcing the soft matrix of titanium alloys (including new generation β-Ti alloys) with hard ceramic precipitates such as borides offers the possibility of substantially enhancing the wear resistance of these composites. The present study discusses the microstructure and wear resistance of laser-deposited boride reinforced composites based on Ti-Nb-Zr-Ta alloys. These composites have been deposited using the LENS TM process from a blend of elemental Ti, Nb, Zr, Ta, and boron powders and consist of complex borides dispersed in a matrix of β-Ti. The wear resistance of these composites has been compared with that of Ti-6Al-4V ELI, the current material of choice for orthopedic femoral implants, against two types of counterfaces, hard Si 3 N 4 and softer SS440C stainless steel. Results suggest a substantial improvement in the wear resistance of the boride reinforced Ti-Nb-Zr-Ta alloys as compared with Ti-6Al-4V ELI against the softer counterface of SS440. The presence of an oxide layer on the surface of these alloys and composites also appears to have a substantial effect in terms of enhanced wear resistance

Interlayer utilization (including metal borides) for subsequent deposition of NSD films via microwave plasma CVD on 316 and 440C stainless steels

Science.gov (United States)

Ballinger, Jared

Diamond thin films have promising applications in numerous fields due to the extreme properties of diamonds in conjunction with the surface enhancement of thin films. Biomedical applications are numerous including temporary implants and various dental and surgical instruments. The unique combination of properties offered by nanostructured diamond films that make it such an attractive surface coating include extreme hardness, low obtainable surface roughness, excellent thermal conductivity, and chemical inertness. Regrettably, numerous problems exist when attempting to coat stainless steel with diamond generating a readily delaminated film: outward diffusion of iron to the surface, inward diffusion of carbon limiting necessary surface carbon precursor, and the mismatch between the coefficients of thermal expansion yielding substantial residual stress. While some exotic methods have been attempted to overcome these hindrances, the most common approach is the use of an intermediate layer between the stainless steel substrate and the diamond thin film. In this research, both 316 stainless steel disks and 440C stainless steel ball bearings were tested with interlayers including discrete coatings and graded, diffusion-based surface enhancements. Titanium nitride and thermochemical diffusion boride interlayers were both examined for their effectiveness at allowing for the growth of continuous and adherent diamond films. Titanium nitride interlayers were deposited by cathodic arc vacuum deposition on 440C bearings. Lower temperature diamond processing resulted in improved surface coverage after cooling, but ultimately, both continuity and adhesion of the nanostructured diamond films were unacceptable. The ability to grow quality diamond films on TiN interlayers is in agreement with previous work on iron and low alloy steel substrates, and the similarly seen inadequate adhesion strength is partially a consequence of the lacking establishment of an interfacial carbide phase

Effect of borides on hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel

Energy Technology Data Exchange (ETDEWEB)

Zhou, Xuan [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Mingjia, E-mail: mingjiawangysu@126.com [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Fu, Yifeng [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Zixi; Li, Yanmei [Yanming Alloy Roll Co. Ltd, Qinhuangdao 066004 (China); Yang, Shunkai; Zhao, Hongchang; Li, Hangbo [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

2017-02-15

To investigate borides effect on the hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel, hot compression tests at the temperatures of 950– 1150 °C and the strain rates of 0.01– 10 s{sup −1} were performed. Flow stress curves indicated that borides increased the material's stress level at low temperature but the strength was sacrificed at temperatures above 1100 °C. A hyperbolic-sine equation was used to characterize the dependence of the flow stress on the deformation temperature and strain rate. The hot deformation activation energy and stress exponent were determined to be 355 kJ/mol and 3.2, respectively. The main factors leading to activation energy and stress exponent of studied steel lower than those of commercial 304 stainless steel were discussed. Processing maps at the strains of 0.1, 0.3, 0.5, and 0.7 showed that flow instability mainly concentrated at 950– 1150 °C and strain rate higher than 0.6 s{sup −1}. Results of microstructure illustrated that dynamic recrystallization was fully completed at both high temperature-low strain rate and low temperature-high strain rate. In the instability region cracks were generated in addition to cavities. Interestingly, borides maintained a preferential orientation resulting from particle rotation during compression. - Highlights: •The decrement of activation energy was affected by boride and boron solution. •The decrease of stress exponent was influenced by composition and Cottrell atmosphere. •Boride represented a preferential orientation caused by particle rotation.

Growth kinetics of boride layers formed on 99.0% purity nickel

Indian Academy of Sciences (India)

abrasion wear, corrosion and high oxidation resistance com- pared with other ... Ni and Ni-base alloys are used in various industrial plants and equipment for their high ... with 1000-grit emery paper before the boronizing process. The boriding ...

Nanosize boride particles in heat-treated nickel base superalloys

International Nuclear Information System (INIS)

Zhang, H.R.; Ojo, O.A.; Chaturvedi, M.C.

2008-01-01

Grain boundary microconstituents in aged nickel-based superalloys were studied by transmission electron microscopy techniques. A nanosized M 5 B 3 boride phase, possibly formed by intergranular solute desegregation-induced precipitation, was positively identified. The presence of these intergranular nanoborides provides reasonable clarification of a previously reported reduction of grain boundary liquation temperature during the weld heat affected zone thermal cycle

Electron momentum distribution and electronic response of ceramic borides

Energy Technology Data Exchange (ETDEWEB)

Heda, N.L. [Department of Pure and Applied Physics, University of Kota, Kota 324005 (India); Meena, B.S.; Mund, H.S. [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001 (India); Sahariya, Jagrati [Department of Physics, Manipal University, Jaipur 303007 (India); Kumar, Kishor [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001 (India); Ahuja, B.L., E-mail: blahuja@yahoo.com [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001 (India)

2017-03-15

Isotropic Compton profiles of transition metal based ceramics TaB and VB have been measured using {sup 137}Cs (661.65 keV) γ-ray Compton spectrometer. The experimental momentum densities are compared with those deduced using linear combination of atomic orbitals (LCAO) with Hartree-Fock (HF), density functional theory (DFT) with Wu-Cohen generalized gradient approximation (WCGGA) and also the hybridization of HF and DFT (namely B3PW and PBE0) schemes. It is found that LCAO-DFT-WCGGA scheme based profiles give an overall better agreement with the experimental data, for both the borides. In addition, we have computed the Mulliken's population (MP) charge transfer data, energy bands, density of states and Fermi surface topology of both the borides using full potential-linearized augmented plane wave (FP-LAPW) and LCAO methods with DFT-WCGGA scheme. Cross-overs of Fermi level by the energy bands corresponding to B-2p and valence d-states of transition metals lead to metallic character in both the compounds. Equal-valence-electron-density profiles and MP analysis suggest more ionic character of VB than that of TaB.

Computer simulation of monolayer growth kinetics of Fe2B phase during the paste-boriding process: Influence of the paste thickness

International Nuclear Information System (INIS)

Keddam, M.

2006-01-01

This paper deals with the effect of boron paste thickness on the study of the monolayer growth kinetics of Fe 2 B phase forming on AISI 1045 steel by the paste-boriding process. A mathematical diffusion model based on the Fick's phenomenological equations was applied in order to estimate the growth rate constant at (Fe 2 B/γ-Fe) interface, the layer thickness of iron boride as well as the associated mass gain depending on the boriding parameters such as time, temperature and surface boron concentration related to the boron paste thickness. The simulation results are found to be in a fairly good agreement with the experimental data derived from the literature

Electrosynthesis of tantalum borides in oxygen-free and oxygen-containing fluoride melts

DEFF Research Database (Denmark)

Polyakova, L.P.; Polyakov, E.G.; Makarova, O.V.

2001-01-01

Results of electrosynthesis of tantalum borides in fluoride and oxyfluoride melts are compared. It is shown that the single-phase X-ray-amorphous micro-layered coatings form only in the latter case. Linear and square-wave voltammetry, complemented by X-ray diffraction analysis, IR spectroscopy...

Characterization of boride-based powders and detonation gun sprayed cermet coatings

International Nuclear Information System (INIS)

Keraenen, J.; Stenberg, T.; Maentylae, T.

1995-01-01

Detonation gun sprayed (DGS) cermet coatings containing complex ternary transition metal boride as hard particles dispersed in a stainless steel or nickel based superalloy matrix have been characterized. Microstructure of the coatings, as well as powders, were studied with optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and analytical transmission electron microscopy (AEM). X-ray microanalysis of the coatings were carried out using energy dispersive X-ray spectrometer (EDS) attached to the SEM and AEM. Moreover, abrasion wear resistance of the coatings was evaluated with a rubber wheel abrasion test equipment. The general microstructure of studied coatings appeared to be heterogeneous in the terms of the distribution, size and crystallographic nature of the phases. Nonetheless, very low porosities were obtained and in the coatings the oxide phase as well as the unmelted particles and the formation of oxide phase were avoided by optimization of DGS parameters. So far the abrasive wear resistance of boride-based cermet coatings is not so good as that of the WC-12Co coatings

Boron-dependency of molybdenum boride electrocatalysts for the hydrogen evolution reaction

International Nuclear Information System (INIS)

Park, Hyounmyung; Encinas, Andrew; Fokwa, Boniface P.T.; Scheifers, Jan P.; Zhang, Yuemei

2017-01-01

Molybdenum-based materials have been considered as alternative catalysts to noble metals, such as platinum, for the hydrogen evolution reaction (HER). We have synthesized four binary bulk molybdenum borides Mo_2B, α-MoB, β-MoB, and MoB_2 by arc-melting. All four phases were tested for their electrocatalytic activity (linear sweep voltammetry) and stability (cyclic voltammetry) with respect to the HER in acidic conditions. Three of these phases were studied for their HER activity and by X-ray photoelectron spectroscopy (XPS) for the first time; MoB_2 and β-MoB show excellent activity in the same range as the recently reported α-MoB and β-Mo_2C phases, while the molybdenum richest phase Mo_2B show significantly lower HER activity, indicating a strong boron-dependency of these borides for the HER. In addition, MoB_2 and β-MoB show long-term cycle stability in acidic solution. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Boron-dependency of molybdenum boride electrocatalysts for the hydrogen evolution reaction

Energy Technology Data Exchange (ETDEWEB)

Park, Hyounmyung; Encinas, Andrew; Fokwa, Boniface P.T. [Department of Chemistry, University of California, Riverside, CA (United States); Department of Chemical and Environmental Engineering, University of California, Riverside, CA (United States); Scheifers, Jan P.; Zhang, Yuemei [Department of Chemistry, University of California, Riverside, CA (United States)

2017-05-08

Molybdenum-based materials have been considered as alternative catalysts to noble metals, such as platinum, for the hydrogen evolution reaction (HER). We have synthesized four binary bulk molybdenum borides Mo{sub 2}B, α-MoB, β-MoB, and MoB{sub 2} by arc-melting. All four phases were tested for their electrocatalytic activity (linear sweep voltammetry) and stability (cyclic voltammetry) with respect to the HER in acidic conditions. Three of these phases were studied for their HER activity and by X-ray photoelectron spectroscopy (XPS) for the first time; MoB{sub 2} and β-MoB show excellent activity in the same range as the recently reported α-MoB and β-Mo{sub 2}C phases, while the molybdenum richest phase Mo{sub 2}B show significantly lower HER activity, indicating a strong boron-dependency of these borides for the HER. In addition, MoB{sub 2} and β-MoB show long-term cycle stability in acidic solution. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Suppression of Boride Formation in Transient Liquid Phase Bonding of Pairings of Parent Superalloy Materials with Different Compositions and Grain Structures and Resulting Mechanical Properties

Science.gov (United States)

Steuer, Susanne; Singer, Robert F.

2014-07-01

Two Ni-based superalloys, columnar grained Alloy 247 and single-crystal PWA1483, are joined by transient liquid phase bonding using an amorphous brazing foil containing boron as a melting point depressant. At lower brazing temperatures, two different morphologies of borides develop in both base materials: plate-like and globular ones. Their ratio to each other is temperature dependent. With very high brazing temperatures, the deleterious boride formation in Alloy 247 can be totally avoided, probably because the three-phase-field moves to higher alloying element contents. For the superalloy PWA1483, the formation of borides cannot be completely avoided at high brazing temperatures as incipient melting occurs. During subsequent solidification of these areas, Chinese-script-like borides precipitate. The mechanical properties (tensile tests at room and elevated temperatures and short-term creep rupture tests at elevated temperatures) for brazed samples without boride precipitation are very promising. Tensile strengths and creep times to 1 pct strain are comparable, respectively, higher than the ones of the weaker parent material for all tested temperatures and creep conditions (from 90 to 100 pct rsp. 175 to 250 pct).

Magnesium, magnesium alloys, and magnesium composites

National Research Council Canada - National Science Library

Gupta, M; Sharon, Nai Mui Ling

2011-01-01

"Properties of Magnesium Composites for Material Scientists, Engineers and Selectors is the first book-length reference to provide an insight into current and future magnesium-based materials in terms...

Identification of an eta boride phase as a crystallization product of a NiMoFeB amorphous alloy

International Nuclear Information System (INIS)

Kim, Y.W.; Rabenberg, L.; Bourell, D.L.

1988-01-01

A new, apparently metastable, Mo--Ni boride phase has been observed in transmission electron microscope samples of rapidly consolidated MoNiFeB metallic glass powders. The phase is cubic with lattice parameter 1.083 nm. Its space group as determined by electron diffraction is Fd3-barm and its approximate composition is Mo 3 Ni 3 B. Because its structure, its composition, and its role as a transition phase are analogous to those of eta carbide (M 6 C) in steels and cemented carbides, this phase has tentatively been named ''eta boride.''

Catalytic activity of metal borides in the reaction of decomposition

International Nuclear Information System (INIS)

Labodi, I.; Korablev, L.I.; Tavadyan, L.A.; Blyumberg, Eh.A.

1982-01-01

Catalytic effect of CoB, MoB 2 , ZrB 2 and NbB 2 , prepared by the method of self-propagating high-temperature synthesis, on decomposition of tertiary butyl hydroperoxide has been studied. A technigue of determination of action mechanism of heterogeneous catalysts in liquid-phase process is suggested. It is established that CoB in contrast to other metal borides catalyzes only hydroperoxide decomposition into radicals

A Simple, General Synthetic Route toward Nanoscale Transition Metal Borides.

Science.gov (United States)

Jothi, Palani R; Yubuta, Kunio; Fokwa, Boniface P T

2018-04-01

Most nanomaterials, such as transition metal carbides, phosphides, nitrides, chalcogenides, etc., have been extensively studied for their various properties in recent years. The similarly attractive transition metal borides, on the contrary, have seen little interest from the materials science community, mainly because nanomaterials are notoriously difficult to synthesize. Herein, a simple, general synthetic method toward crystalline transition metal boride nanomaterials is proposed. This new method takes advantage of the redox chemistry of Sn/SnCl 2 , the volatility and recrystallization of SnCl 2 at the synthesis conditions, as well as the immiscibility of tin with boron, to produce crystalline phases of 3d, 4d, and 5d transition metal nanoborides with different morphologies (nanorods, nanosheets, nanoprisms, nanoplates, nanoparticles, etc.). Importantly, this method allows flexibility in the choice of the transition metal, as well as the ability to target several compositions within the same binary phase diagram (e.g., Mo 2 B, α-MoB, MoB 2 , Mo 2 B 4 ). The simplicity and wide applicability of the method should enable the fulfillment of the great potential of this understudied class of materials, which show a variety of excellent chemical, electrochemical, and physical properties at the microscale. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Boron-Based Hydrogen Storage: Ternary Borides and Beyond

Energy Technology Data Exchange (ETDEWEB)

Vajo, John J. [HRL Laboratories, LLC, Malibu, CA (United States)

2016-04-28

DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ≥11 wt% and ≥80 g/L that can deliver hydrogen and be recharged at moderate temperatures (≤100 °C) and pressures (≤100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron-based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slow rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement.

Structure of superhard tungsten tetraboride: A missing link between MB2 and MB12 higher borides

Science.gov (United States)

Lech, Andrew T.; Turner, Christopher L.; Mohammadi, Reza; Tolbert, Sarah H.; Kaner, Richard B.

2015-01-01

Superhard metals are of interest as possible replacements with enhanced properties over the metal carbides commonly used in cutting, drilling, and wear-resistant tooling. Of the superhard metals, the highest boride of tungsten—often referred to as WB4 and sometimes as W1–xB3—is one of the most promising candidates. The structure of this boride, however, has never been fully resolved, despite the fact that it was discovered in 1961—a fact that severely limits our understanding of its structure–property relationships and has generated increasing controversy in the literature. Here, we present a new crystallographic model of this compound based on refinement against time-of-flight neutron diffraction data. Contrary to previous X-ray–only structural refinements, there is strong evidence for the presence of interstitial arrangements of boron atoms and polyhedral bonding. The formation of these polyhedra—slightly distorted boron cuboctahedra—appears to be dependent upon the defective nature of the tungsten-deficient metal sublattice. This previously unidentified structure type has an intermediary relationship between MB2 and MB12 type boride polymorphs. Manipulation of the fractionally occupied metal and boron sites may provide insight for the rational design of new superhard metals. PMID:25733870

Oxide films on magnesium and magnesium alloys

International Nuclear Information System (INIS)

Shih, T.-S.; Liu, J.-B.; Wei, P.-S.

2007-01-01

Magnesium alloys are very active and readily ignite during heating and melting. In this study, we discuss the combustion of magnesium and magnesium alloys and propose prospective anti-ignition mechanisms for magnesium alloys during the heating process. When magnesium and magnesium alloys were heated in air, the sample surfaces produced layers of thermally formed oxides. These thermally formed oxides played an important role in affecting the combustion of the magnesium and magnesium alloys. When magnesium was heated in air, brucite that formed in the early stage was then transformed into periclase by dehydroxylation. By extending the heating time, more periclase formed and increased in thickness which was associated with microcracks formation. When magnesium was heated in a protective atmosphere (SF 6 ), a film of MgF 2 formed at the interface between the oxide layer and the Mg substrate. This film generated an anti-ignition behavior which protected the substrate from oxidation. When solution-treated AZ80 alloy was heated, spinel developed at the interface between the thermally formed oxide layer and the Mg substrate, improving the anti-ignition properties of the substrate. In addition, we also explain the effects of beryllium in an AZB91 alloy on the ignition-proofing behavior

Borides - a new generation of highly resistant materials?

International Nuclear Information System (INIS)

Telle, R.

1988-01-01

High-duty ceramics are on advance in all sectors where materials with extremely good resistance to high temperatures and wear are required. The group of oxides, nitrides and carbides in use for quite a time now recently has been increased by the metal borides which offer among others economic advantages in certain applications. The drawbacks of these materials still to be reduced are their brittleness and susceptibility to oxidation and corrosion. Current research work on the thermodynamics of such systems, on the interaction between structure and properties, and on means to improve strength and resistance to wear are expected to soon open up new applications. (orig.) [de

High Temperature Sliding Wear of NiAl-based Coatings Reinforced by Borides

Directory of Open Access Journals (Sweden)

Oleksandr UMANSKYI

2016-05-01

Full Text Available The development of composite materials (CM in the systems “metal-refractory compound” is one of the up-to-date trends in design of novel materials aimed at operating under the conditions of significant loads at high temperature. To design such material, NiAl, which is widely used for deposition of protective coatings on parts of gas-turbine engines, was selected for a matrix. To strengthen a NiAl under the conditions of intense wear and a broad temperature range (up to 1000 °C, it is reasonable to add refractory inclusions. Introduction of refractory borides into matrix leads to a marked increase in metal wear resistance. In order to research the behavior of the designed composites at high temperatures and to study the influence of oxides on the friction processes, the authors carried out high temperature oxidation of CM of the above systems at 1000 °С for 90 min. It was determined that all of the composites were oxidized selectively and that the thickness of oxide layers formed on the boride inclusions is 3 – 7 times that on the oxides formed on the NiAl matrix. The mechanism of wear of gas-thermal coatings of the NiAl – МеB2 systems was studied for conditions of high temperature tribotests using the «pin-on-disc» technique. The obtained results indicate that introduction of TiB2, CrB2 and ZrB2 leads to their more intense oxidation during high temperature tribotests as compared to the matrix. The oxides formed on refractory borides act as solid lubricants, which promote a decrease in wear of the contact friction pairs. For more detailed investigation of the effect of tribo-oxidation products on the friction processes, tribotests were conducted for prior oxidized (at 900 °С coatings NiAl – 15 wt.% CrB2 (TiB2, ZrB2.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.8093

A crossover from high stiffness to high hardness. The case of osmium and its borides

International Nuclear Information System (INIS)

Bian, Yongming; Li, Anhu; Liu, Xiaomei; Shanghai Univ. of Engineering Science; Liang, Yongcheng

2016-01-01

Transition-metal light-element compounds are currently raising great expectations for hard and superhard materials. Using the widely attracting osmium (Os) and its borides (OsB, Os_2B_3 and OsB_2) as prototypes, we demonstrate by first-principles calculations that heavy transition metals, which possess high stiffness but low hardness, can be converted into highly hard materials by incorporating of light elements to form compounds. Such a crossover is a manifestation that the underlying sources of high stiffness and high hardness are fundamentally different. The stiffness is related to elastic deformation that is closely associated with valence electron density, whereas the hardness depends strongly on plastic deformation that is determined by bonding nature. Therefore, the incorporation of light atoms into transition metal should be a valid pathway of designing hard and superhard materials. This strategy is in principle also applicable to other transition-metal borides, carbides, and nitrides.

Surface decoration through electrostatic interaction leading to enhanced reactivity: Low temperature synthesis of nanostructured chromium borides (CrB and CrB2)

International Nuclear Information System (INIS)

Menaka,; Kumar, Bharat; Kumar, Sandeep; Ganguli, A.K.

2013-01-01

The present study describes a novel low temperature route at ambient pressure for the synthesis of nanocrystalline chromium borides (CrB and CrB 2 ) without using any flux or additives. The favorable and intimate mixing of nanoparticles of chromium acetate (Cr source) and boron forms an active chromium–boron precursor which decomposes at much lower temperature (400 °C) to form CrB (which is ∼1000 °C less than the known ambient pressure synthesis). The chromium acetate nanoparticles (∼5 nm) decorate the larger boron particles (150–200 nm) due to electrostatic interactions resulting from opposing surface charges of boron (zeta potential:+48.101 mV) and chromium acetate (zeta potential:−4.021 mV) in ethanolic medium and is evident in the TEM micrographs. The above method leads to the formation of pure CrB film like structure at 400 °C and nanospheres (40–60 nm) at 600 °C. Also, chromium diboride (CrB 2 ) nanoparticles (25 nm) could be obtained at 1000 °C. - Graphical abstract: Variation of surface charge of reactants, precursor and the products, chromium borides (CrB and CrB 2 ). Highlights: ► Novel borothermal reduction process for synthesis of chromium boride. ► Significant lowering of reaction temperature to obtain nanocrystalline chromium boride. ► Enhanced reactivity due to appropriate surface interactions

Successive determinations of metals and boron in metal borides by chelatometric and alkalimetric titrations

International Nuclear Information System (INIS)

Takahashi, Yasuo; Higashi, Iwami; Atoda, Tetzuzo

1976-01-01

Based on the investigation of chemical reactivities of metal borides and of the metal chelate effects on the alkalimetric titration of boron, a method of successive determinations of metals and boron of Mn-, Fe-, Cu- and Al-borides has been developed. The procedure is as follows: (1) Mn-, Fe- and Cu-borides: Dissolve 10 to 30 mg of a sample in a mixture of 3 ml of 3N HNO 3 , 3 ml of 3N H 2 SO 4 and 0.3 ml of 10% H 2 O 2 by heating in a quartz flask equipped with a reflux condenser. Cool the solution obtained, add 0.02M CyDTA solution in excess and neutralize to pH 3 with 2N NaOH solution. Boil the solution for several minutes to ensure the formation of the metal chelate. After cooling, adjust the pH exactly to 6.7 with 0.5 M NaHCO 3 solution, and then determine the metal concentration by back-titrating the excess CyDTA with 0.01M ZnSO 4 solution using MTB as an indicator. After the titration is over, make the solution to pH 3 with 2N H 2 SO 4 and boil for several minutes to expel CO 2 . Cool the solution, adjust the pH exactly to 7.0 with 0.1N CO 2 -free NaOH solution and add 5 g of mannite and ten drops of 0.1% phenolphthalein solution. Finally, titrate the mannite-boric acid complex with 0.05N NaOH solution until the pink tinge is observed (pH 8.2). (2) Al-boride: Fuse 10 to 30 mg of a sample with a mixture of 1.5 g of Na 2 CO 3 and 0.3 g of KNO 3 in a nickel crucible. Digest the melt with water and filter off the residue (nickel oxide). Add 0.01 M EDTA solution in excess to the filterate and make it to pH 3 with 2N H 2 SO 4 . Analytical Results obtained by the present method agree well with those by other methods. The present method takes only 40 minutes, whereas several hours are required to determine metal and boron by other methods. (auth.)

A novel route to nanosized molybdenum boride and carbide and/or metallic molybdenum by thermo-synthesis method from MoO3, KBH4, and CCl4

International Nuclear Information System (INIS)

Li Yuanzhi; Fan Yining; Chen Yi

2003-01-01

Nanosized molybdenum boride and carbide were synthesized from MoO 3 , KBH 4 , and CCl 4 by thermo-synthesis method at lower temperature. The relative content of Mo, Mo 2 C, and molybdenum boride in the product was decided by the molar ratio between MoO 3 , KBH 4 , and CCl 4 . Increasing the molar ratio of CCl 4 to MoO 3 was favorable to the production of Mo 2 C. Increasing the molar ratio of KBH 4 to MoO 3 was favorable to the production of molybdenum boride. By carefully adjusting the reaction conditions and annealing in Ar at 900 deg. C, a single phase of MoB could be obtained

Formation of boride layers on steel substrates

International Nuclear Information System (INIS)

Stergioudis, G.

2006-01-01

Boronizing coatings were prepared by means of pack cementation technique. It was found that using the appropriate substrate and controlling parameters of the boribing process such as boron activity of the mixture, temperature and time of treatment, it is possible to obtain a structure predominantly consisting of the Fe 2 B phase. In the present study low alloy ferritic steels were chosen as substrates. Changing the boron carbide concentration in the mixture and the temperature and time of boronizing process the conditions of the boronizing were altered. As a result the formation of the Fe 2 B phase is enhanced. Characterization of the as-borided steels is discussed based on X-ray diffraction and Curie temperature measurements. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Magnesium Gluconate

Science.gov (United States)

Magnesium gluconate is used to treat low blood magnesium. Low blood magnesium is caused by gastrointestinal disorders, prolonged vomiting or ... disease, or certain other conditions. Certain drugs lower magnesium levels as well.This medication is sometimes prescribed ...

A crossover from high stiffness to high hardness. The case of osmium and its borides

Energy Technology Data Exchange (ETDEWEB)

Bian, Yongming; Li, Anhu [Tongji Univ., Shanghai (China). School of Mechanical Engineering; Liu, Xiaomei [Tongji Univ., Shanghai (China). School of Mechanical Engineering; Shanghai Univ. of Engineering Science (China). College of Mechanical Engineering; Liang, Yongcheng [Shanghai Ocean Univ. (China). College of Engineering Science and Technology

2016-07-01

Transition-metal light-element compounds are currently raising great expectations for hard and superhard materials. Using the widely attracting osmium (Os) and its borides (OsB, Os{sub 2}B{sub 3} and OsB{sub 2}) as prototypes, we demonstrate by first-principles calculations that heavy transition metals, which possess high stiffness but low hardness, can be converted into highly hard materials by incorporating of light elements to form compounds. Such a crossover is a manifestation that the underlying sources of high stiffness and high hardness are fundamentally different. The stiffness is related to elastic deformation that is closely associated with valence electron density, whereas the hardness depends strongly on plastic deformation that is determined by bonding nature. Therefore, the incorporation of light atoms into transition metal should be a valid pathway of designing hard and superhard materials. This strategy is in principle also applicable to other transition-metal borides, carbides, and nitrides.

Synthesis, Structure, and Properties of Refractory Hard-Metal Borides

Science.gov (United States)

Lech, Andrew Thomas

As the limits of what can be achieved with conventional hard compounds, such as tungsten carbide, are nearing reach, super-hard materials are an area of increasing industrial interest. The refractory hard metal borides, such as ReB2 and WB4, offer an increasingly attractive alternative to diamond and cubic boron nitride as a next-generation tool material. In this Thesis, a thorough discussion is made of the progress achieved by our laboratory towards understanding the synthesis, structure, and properties of these extremely hard compounds. Particular emphasis is placed on structural manipulation, solid solution formation, and the unique crystallographic manifestations of what might also be called "super-hard metals".

Microstructural evaluation of a low carbon steel submitted to boriding treatment pre and post GTAW welding; Avaliacao microestrutural de um aco de baixo carbono submetido ao tratamento de boretacao pre e pos-soldagem GTAW

Energy Technology Data Exchange (ETDEWEB)

Pollnow, Edilson Nunes; Osorio, Alice Goncalves, E-mail: edilson.pollnow@hotmail.com, E-mail: osorio.alice@gmail.com [Universidade Federal de Pelotas (CDTec/UFPel), Pelotas, RS (Brazil). Centro de Desenvolvimento Tecnologico; Araujo, Douglas Bezerra de, E-mail: dbaraujo@ufu.br [Universidade Federal de Uberlandia (FEMEC/UFU), Uberlandia, MG (Brazil). Faculdade de Engenharia Mecanica; Passos, Thais Andrezza dos; Souza, Daniel, E-mail: thais.andrezza.passos@gmail.com, E-mail: danielsouza@furg.br [Universidade Federal do Rio Grande (EE/FURG), Rio Grande, RS (Brazil). Escola de Engenharia

2017-04-15

Studies on surface engineering area are given great importance due to the improvement that surface modifications provide to materials. With a global market that has the need to provide parts and equipment with extended service life and low cost, to support stringent requests and thus maintain its high performance, surface treatments may bring what was impossible into reality. Among the surface treatments that have received attention recently, we have the thermochemical process of boriding. The boriding process consists of saturate the surface of steels and metal alloys with boron. This saturation provides an increase in the surface properties not inherent to the base metal, such as hardness, resistance to abrasion and corrosion. Although the properties of boriding steels have already been studied, the effects that the boriding process perform on the steel during or after the welding processes are not known. Hence, it is the purpose of this study to evaluate the microstructure of a low carbon steel treated with boriding before and after GTAW welding. The results indicated poor metallurgical weldability of low carbon steel with boride layer, with the presence of solidification cracks. Nonetheless, the steel welded previous to boring treatment presented a more ductile nucleus, with harder surface. Although the values of hardness within the nucleus of the steel had dropped drastically at the welded zone after the boring, the surface of this steel showed higher values of hardness due to the boriding layer. This fact should be considered when applications where wear resistance is needed. (author)

Production of magnesium metal

Science.gov (United States)

Blencoe, James G [Harriman, TN; Anovitz, Lawrence M [Knoxville, TN; Palmer, Donald A [Oliver Springs, TN; Beard, James S [Martinsville, VA

2010-02-23

A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention further relates to a process for production of magnesium metal or a magnesium compound where an external source of carbon dioxide is not used in any of the reactions of the process. The invention also relates to the magnesium metal produced by the processes described herein.

Timeline (Bioavailability) of Magnesium Compounds in Hours: Which Magnesium Compound Works Best?

Science.gov (United States)

Uysal, Nazan; Kizildag, Servet; Yuce, Zeynep; Guvendi, Guven; Kandis, Sevim; Koc, Basar; Karakilic, Aslı; Camsari, Ulas M; Ates, Mehmet

2018-04-21

Magnesium is an element of great importance functioning because of its association with many cellular physiological functions. The magnesium content of foods is gradually decreasing due to food processing, and magnesium supplementation for healthy living has become increasingly popular. However, data is very limited on the bioavailability of various magnesium preparations. The aim of this study is to investigate the bioavailability of five different magnesium compounds (magnesium sulfate, magnesium oxide, magnesium acetyl taurate, magnesium citrate, and magnesium malate) in different tissues. Following a single dose 400 mg/70 kg magnesium administration to Sprague Dawley rats, bioavailability was evaluated by examining time-dependent absorption, tissue penetration, and the effects on the behavior of the animals. Pharmacokinetically, the area under the curve calculation is highest in the magnesium malate. The magnesium acetyl taurate was found to have the second highest area under the curve calculation. Magnesium acetyl taurate was rapidly absorbed, able to pass through to the brain easily, had the highest tissue concentration level in the brain, and was found to be associated with decreased anxiety indicators. Magnesium malate levels remained high for an extended period of time in the serum. The commonly prescribed dietary supplements magnesium oxide and magnesium citrate had the lowest bioavailability when compared to our control group. More research is needed to investigate the bioavailability of magnesium malate and acetyl taurate compounds and their effects in specific tissues and on behavior.

Quantity, size and distribution of borides for aluminium grain refinement by neutron-induced autoradiography (NIAR). Pt. 2

International Nuclear Information System (INIS)

Rachlitz, R.; Gaertner, S.; Holze, J.; Krumnacker, M.

1990-01-01

Al-Ti-B grain refiners improve the cast structure of aluminium and its alloys, but also cause problems related to the great hardness of the borides and their tendency to agglomerate and settle. Accurate information about the distribution, quantity and size of the TiB 2 particles is needed if material properties are to be improved and the quantity of additives minimized. This information is obtained mostly by NIAR. In laboratory-scale tests Al 99.8 and Al 99.5 were refined using different master alloys added in various quantities. In all cases the commercial master alloy gave the best refining effect. Besides boride particle size distribution and the presence of nuclei and nucleus stabilizers, morphological properties (duplex particles) are obviously of essential importance. It has been demonstrated that the TiB 2 size distribution values determined by NIAR are comparable with those established by optical microscopy measurements. (orig.) [de

Magnesium and Osteoporosis

Directory of Open Access Journals (Sweden)

Ferda Özdemir

2004-03-01

Full Text Available Osteoporosis (OP is a condition of bone fragility resulting from micro-architectural deterioration and decreased bone mass. OP depends on the interaction of genetic, hormonal, environmental and nutritional factors. Chronic low intakes of vitamin D and possibly magnesium, zinc, fluoride and vitamins K, B12, B6 and folic acid may predispose to osteoporosis. Magnesium is a mineral needed by every cell of your body. It helps maintain normal muscle and nerve function, keeps heart rhythm steady, and bones strong. Mg serves as co-factors for enzymes that help build bone matrix. Magnesium deficiency occurs due to excessive loss of magnesium in urine, gastrointestinal system disorders that cause a loss of magnesium or limit magnesium absorption, or a chronic low intake of magnesium. Signs of magnesium deficiency include confusion, disorientation, loss of appetite, depression, muscle contractions and cramps, tingling, numbness, abnormal heart rhythms, coronary spasm, and seizures. Magnesium deficiency alters calcium metabolism and the hormones that regulates calcium. Several studies have suggested that magnesium supplementation may improve bone mineral density and prevent fractures.

Mechanochemically Driven Syntheses of Boride Nanomaterials

Science.gov (United States)

Blair, Richard G.

Solid state metathesis reactions have proven to be a viable route to the production of unfunctionalized nanomaterials. However, current implementations of this approach are limited to self-propagating reactions. We have been investigating mechanically driven metathesis reactions. The use of high-energy ball mills allows control of crystallite sizes without the use of a capping group. Reinforcement materials with crystallite sizes on the order of 5-30 nm can be produced in such a manner. Borides are of particular interest due to their strength, high melting point, and electrical conductivity. The ultimate goal of this work is to prepare oxide and capping group-free nanoparticles suitable for incorporation in thermoelectric, polymer, and ceramic composites. Ultimately this work will facilitate the production of improved thermoelectric materials that will provide robust, deployable, power generation modules to supplement or replace fuel cell, Stirling, and battery-derived power sources. It will also result in scalable, bulk syntheses of tough, refractory, conductive nanomaterials for polymer composites with improved electrical properties, ceramic composites with enhanced fracture toughness, and composites with enhanced neutron reflectance and/or absorbance.

Magnesium Borohydride: From Hydrogen Storage to Magnesium Battery**

OpenAIRE

Mohtadi, Rana; Matsui, Masaki; Arthur, Timothy S; Hwang, Son-Jong

2012-01-01

Beyond hydrogen storage: The first example of reversible magnesium deposition/stripping onto/from an inorganic salt was seen for a magnesium borohydride electrolyte. High coulombic efficiency of up to 94 % was achieved in dimethoxyethane solvent. This Mg(BH_4)_2 electrolyte was utilized in a rechargeable magnesium battery.

Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from the Elements in the Laser-Heated Diamond Anvil Cell and Their Structure-Property Relations

Directory of Open Access Journals (Sweden)

Lkhamsuren Bayarjargal

2011-09-01

Full Text Available Transition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p; T stability, compressibility and hardness is described as obtained from experiments.

Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from the Elements in the Laser-Heated Diamond Anvil Cell and Their Structure-Property Relations

Science.gov (United States)

Friedrich, Alexandra; Winkler, Björn; Juarez-Arellano, Erick A.; Bayarjargal, Lkhamsuren

2011-01-01

Transition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p,T) stability, compressibility and hardness is described as obtained from experiments. PMID:28824101

Electronic Structure Properties and a Bonding Model of Thermoelectric Half-Heusler and Boride Phases

Science.gov (United States)

Simonson, Jack William

Half-Heusler alloys MNiSn and MCoSb (M = Ti, Zr, Hf) and layered boride intermetallics with structure types YCrB4 and Er 3CrB7 were designed, synthesized, and characterized. The thermoelectric properties of these two classes of alloys were measured from room temperature to 1100 K with the intent of indirectly studying their electronic structure properties and gauging not only their suitability but that of related alloys for high temperature thermoelectric power generation. In the case of the half-Heusler alloys, transition metals were substituted to both the M and Ni/Co sites to study the resultant modifications of the d-orbital-rich portion of the electronic structure near the Fermi energy. This modification and subsequent pinning of the Fermi energy within the gap is discussed herein in terms of first principles electronic structure calculations from the literature. In the half-Heusler alloys, it was found that substitution of transition metals invariably led to a decrease in the thermopower, while the resistivity typically maintained its semiconducting trend. On the other hand, Sn doping in MCoSb type alloys -- a dopant that has been known for some time to be efficient -- was shown to result in high ZT at temperatures in excess of 1000 K. Moreover, the band gaps of the transition metal-doped alloys measured in this work offer insight into the discrepancy between the predicted and measured band gaps in the undoped parent compositions. In the case of the layered boride alloys, on the other hand, few electronic calculations have been published, thus prompting the generalization of a well-known electron counting rule -- which is typically used to study molecular organometallics, boranes, and metallocenes -- to predict the trends in the densities of states of crystalline solids that possess the requisite deltahedral bonding geometry. In accordance with these generalized electronic counting rules, alloys of the form RMB4 (R = Y, Gd, Ho; M = Cr, Mo, W) were measured to

Magnesium borohydride: from hydrogen storage to magnesium battery.

Science.gov (United States)

Mohtadi, Rana; Matsui, Masaki; Arthur, Timothy S; Hwang, Son-Jong

2012-09-24

Beyond hydrogen storage: The first example of reversible magnesium deposition/stripping onto/from an inorganic salt was seen for a magnesium borohydride electrolyte. High coulombic efficiency of up to 94 % was achieved in dimethoxyethane solvent. This Mg(BH(4))(2) electrolyte was utilized in a rechargeable magnesium battery. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal properties of zirconium diboride -- transition metal boride solid solutions

Science.gov (United States)

McClane, Devon Lee

This research focuses on the thermal properties of zirconium diboride (ZrB2) based ceramics. The overall goal was to improve the understanding of how different transition metal (TM) additives influence thermal transport in ZrB2. To achieve this, ZrB2 with 0.5 wt% carbon, and 3 mol% of individual transition metal borides, was densified by hot-press sintering. The transition metals that were investigated were: Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, and Re. The room temperature thermal diffusivities of the compositions ranged from 0.331 cm2/s for nominally pure ZrB2 to 0.105 cm2/s for (Zr,Cr)B2 and converged around 0.155cm2/s at higher temperatures for all compositions. Thermal conductivities were calculated from the diffusivities, using temperature-dependent values for density and heat capacity. The electron contribution to thermal conductivity was calculated from measured electrical resistivity according to the Wiedemann-Franz law. The phonon contribution to thermal conductivity was calculated by subtracting the electron contribution from the total thermal conductivity. Rietveld refinement of x-ray diffraction data was used to determine the lattice parameters of the compositions. The decrease in thermal conductivity for individual additives correlated directly to the metallic radius of the additive. Additional strain appeared to exist for additives when the stable TM boride for that metal had different crystal symmetries than ZrB2. This research provided insight into how additives and impurities affect thermal transport in ZrB2. The research potentially offers a basis for future modeling of thermal conductivity in ultra-high temperature ceramics based on the correlation between metallic radius and the decrease in thermal conductivity.

Magnesium in pregnancy.

Science.gov (United States)

Dalton, Lynne M; Ní Fhloinn, Deirdre M; Gaydadzhieva, Gergana T; Mazurkiewicz, Ola M; Leeson, Heather; Wright, Ciara P

2016-09-01

Magnesium deficiency is prevalent in women of childbearing age in both developing and developed countries. The need for magnesium increases during pregnancy, and the majority of pregnant women likely do not meet this increased need. Magnesium deficiency or insufficiency during pregnancy may pose a health risk for both the mother and the newborn, with implications that may extend into adulthood of the offspring. The measurement of serum magnesium is the most widely used method for determining magnesium levels, but it has significant limitations that have both hindered the assessment of deficiency and affected the reliability of studies in pregnant women. Thus far, limited studies have suggested links between magnesium inadequacy and certain conditions in pregnancy associated with high mortality and morbidity, such as gestational diabetes, preterm labor, preeclampsia, and small for gestational age or intrauterine growth restriction. This review provides recommendations for further study and improved testing using measurement of red cell magnesium. Pregnant women should be counseled to increase their intake of magnesium-rich foods such as nuts, seeds, beans, and leafy greens and/or to supplement with magnesium at a safe level. © The Author(s) 2016. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Improving hardness and toughness of boride composites based on aluminum magnesium boride

Science.gov (United States)

Peters, Justin Steven

The search for new super-hard materials has usually focused on strongly bonded, highly symmetric crystal structures similar to diamond. The two hardest single-phase materials, diamond and cubic boron nitride (cBN), are metastable, and both must be produced at high temperatures and pressures, which makes their production costly. In 2000, a superhard composite based on a low-symmetry, boron-rich compound was reported. Since then, many advances have been made in the study of this AlMgB14--TiB2 composite. The composite has been shown to exhibit hardness greater than either of its constituent phases, relying on its sub-micron microstructure to provide hardening and strengthening mechanisms. With possible hardness around 40 GPa, an AlMgB 14--60 vol% TiB2 approaches the hardness of cBN, yet is amenable to processing under ambient pressure conditions. There are interesting aspects of both the AlMgB14 and TiB 2 phases. AlMgB14 is comprised of a framework of boron, mostly in icosahedral arrangements. It is part of a family of 12 known compounds with the same boron lattice, with the metal atoms replaced by Li, Na, Y or a number of Lanthanides. Another peculiar trait of this family of compounds is that every one contains a certain amount of intrinsic vacancies on one or both of the metal sites. These vacancies are significant, ranging from 3 to 43% of sites depending on the composition. TiB2 is a popular specialty ceramic material due to its high hardness, moderate toughness, good corrosion resistance, and high thermal and electrical conductivity. The major drawback is the difficulty of densification of pure TiB2 ceramics. A combination of sintering aids, pressure, and temperatures of 1800°C are often required to achieve near full density articles. The AlMgB14--TiB2 composites can achieve 99% density from hotpressing at 1400°C. This is mostly due to the preparation of powders by a high-energy milling technique known as mechanical alloying. The resulting fine powders have high activity, and Fe from wear debris acts as a sintering aid. Mechanical alloying improves the sinterability of the composite material, it has the same effect on pure TiB2. TiB 2 processed by high-energy milling has been found to achieve 99% theoretical density at 1400°C with the addition of ˜1 wt% Fe. Both the AlMgB14--TiB2 composites and pure TiB2 produced from these methods have enhanced mechanical properties due to their fine microstructures. These materials show exceptional promise in the field of wear resistance. This includes cutting tools, erosion resistant coatings, and low-friction sliding contacts to name a few. Under certain wear conditions, the composite material can show performance on par with that of current high-end cBN and WC materials tailored for wear resistance. The composite material also exhibits low reactivity with Ti alloys, a pre-requisite for effective machining of these alloys, a trait that few hard materials possess.

Quantitative electron probe microanalysis of borides in aluminium

International Nuclear Information System (INIS)

Karduck, P.; Schuerhoff, H.J.; Burchard, W.G.

1983-01-01

A procedure for the quantitative analysis of borides in aluminium was introduced. For this purpose the optimal apparative boundary conditions for the EPMA of boron were worked out. With these conditions a satisfactory peak to background ratio of 57 could be achieved for B-Kα-radiation. By application of this method the following conclusion should be drawn concerning the kind of nuclei during grain refinement of aluminium with titanium and boron: For grain refinement of aluminium with titanium and boron in the hypoperitectic region of the binary system Al-Ti TiB 2 -particles in clusters provide the high efficiency of refinement. This entails that the TiB 2 -particles already present in the master alloy remain inert in the melt. Hence, the good efficiency of refinement in this region cannot be attributed to the presence of particles like Al 3 Ti, AlB 2 or (Al, Ti) B 2 . (Author)

Magnesium stannide as a high-capacity anode for magnesium-ion batteries

Science.gov (United States)

Nguyen, Dan-Thien; Song, Seung-Wan

2017-11-01

Driven by the limited global resources of lithium, magnesium metal batteries are considered as potential energy storage systems. The battery chemistry of magnesium metal anode, however, limits the selection of electrolytes, cathode materials and working temperature, making the realization of magnesium metal batteries complicated. Herein, we report the development of a new magnesium-insertion anode, magnesium stannide (Mg2Sn), and demonstrate reversible electrochemical Mg2+-extraction and insertion of Mg2Sn anode at 0.2 V versus Mg, delivering discharge capacity of 270 mAhg-1 in a half-cell with the electrolyte of PhMgCl/THF and enabling of room temperature magnesium-ion batteries with Mg2Sn anode combined with Mg-free oxide cathode and conventional-type electrolyte of Mg(TFSI)2/diglyme. The combination of Mg2Sn anode with various cathodes and electrolytes holds great promise for enabling room temperature magnesium-ion batteries.

Effect of magnesium deficiency on renal magnesium and calcium transport in the rat.

OpenAIRE

Carney, S L; Wong, N L; Quamme, G A; Dirks, J H

1980-01-01

Recollection of micropuncture experiments were performed on acutely thyroparathyroidectomized rats rendered magnesium deficient by dietary deprivation. Urinary magnesium excretion fell from a control of 15 to 3% of the filtered load after magnesium restriction. The loop of Henle, presumably the thick ascending limb, was the major modulator for renal magnesium homeostasis. The transport capacity for magnesium, however, was less in deficient rats than control animals. Absolute magnesium reabsor...

Magnesium, magnesium alloys, and magnesium composites

National Research Council Canada - National Science Library

Gupta, M; Sharon, Nai Mui Ling

2011-01-01

.... With the popularity of magnesium-based materials in the automotive, aerospace, electronics, and sports equipment industries, and its unique role as a lightweight, energy-saving and high-performance...

Myth or Reality-Transdermal Magnesium?

Science.gov (United States)

Gröber, Uwe; Werner, Tanja; Vormann, Jürgen; Kisters, Klaus

2017-07-28

In the following review, we evaluated the current literature and evidence-based data on transdermal magnesium application and show that the propagation of transdermal magnesium is scientifically unsupported. The importance of magnesium and the positive effects of magnesium supplementation are extensively documented in magnesium deficiency, e.g., cardiovascular disease and diabetes mellitus. The effectiveness of oral magnesium supplementation for the treatment of magnesium deficiency has been studied in detail. However, the proven and well-documented oral magnesium supplementation has become questioned in the recent years through intensive marketing for its transdermal application (e.g., magnesium-containing sprays, magnesium flakes, and magnesium salt baths). In both, specialist and lay press as well as on the internet, there are increasing numbers of articles claiming the effectiveness and superiority of transdermal magnesium over an oral application. It is claimed that the transdermal absorption of magnesium in comparison to oral application is more effective due to better absorption and fewer side effects as it bypasses the gastrointestinal tract.

Magnesium stearine production via direct reaction of palm stearine and magnesium hydroxide

Science.gov (United States)

Pratiwi, M.; Ylitervo, P.; Pettersson, A.; Prakoso, T.; Soerawidjaja, T. H.

2017-06-01

The fossil oil production could not compensate with the increase of its consumption, because of this reason the renewable alternative energy source is needed to meet this requirement of this fuel. One of the methods to produce hydrocarbon is by decarboxylation of fatty acids. Vegetable oil and fats are the greatest source of fatty acids, so these can be used as raw material for biohydrocarbon production. From other researchers on their past researchs, by heating base soap from divalent metal, those metal salts will decarboxylate and produce hydrocarbon. This study investigate the process and characterization of magnesium soaps from palm stearine by Blachford method. The metal soaps are synthesized by direct reaction of palm stearine and magnesium hydroxide to produce magnesium stearine and magnesium stearine base soaps at 140-180°C and 6-10 bar for 3-6 hours. The operation process which succeed to gain metal soaps is 180°C, 10 bar, for 3-6 hours. These metal soaps are then compared with commercial magnesium stearate. Based on Thermogravimetry Analysis (TGA) results, the decomposition temperature of all the metal soaps were 250°C. Scanning Electron Microscope with Energy Dispersive X-ray (SEM-EDX) analysis have shown the traces of sodium sulphate for magnesium stearate commercial and magnesium hydroxide for both type of magnesium stearine soaps. The analysis results from Microwave Plasma-Atomic Emission Spectrometry (MP-AES) have shown that the magnesium content of magnesium stearine approximate with magnesium stearate commercial and lower compare with magnesium stearine base soaps. These experiments suggest that the presented saponification process method could produced metal soaps comparable with the commercial metal soaps.

Low magnesium level

Science.gov (United States)

Low magnesium level is a condition in which the amount of magnesium in the blood is lower than normal. The medical ... that convert or use energy ( metabolism ). When the level of magnesium in the body drops below normal, ...

System and process for production of magnesium metal and magnesium hydride from magnesium-containing salts and brines

Science.gov (United States)

McGrail, Peter B.; Nune, Satish K.; Motkuri, Radha K.; Glezakou, Vassiliki-Alexandra; Koech, Phillip K.; Adint, Tyler T.; Fifield, Leonard S.; Fernandez, Carlos A.; Liu, Jian

2016-11-22

A system and process are disclosed for production of consolidated magnesium metal products and alloys with selected densities from magnesium-containing salts and feedstocks. The system and process employ a dialkyl magnesium compound that decomposes to produce the Mg metal product. Energy requirements and production costs are lower than for conventional processing.

Anticorrosive magnesium hydroxide coating on AZ31 magnesium alloy by hydrothermal method

International Nuclear Information System (INIS)

Zhu Yanying; Wu Guangming; Xing Guangjian; Li Donglin; Zhao Qing; Zhang Yunhong

2009-01-01

Magnesium alloys are potential biodegradable biomaterials in orthopedic surgery. However, the rapid degradation rate has limited their application in biomedical field. A great deal of studies have been done to improve the resistance of magnesium alloys. In this article, An anticorrosive magnesium hydroxide coating with a thickness of approximately 100μm was formed on an AZ31 magnesium alloy by hydrothermal method. The morphology of the coatings were observed by an optical microscope and SEM. And the samples were soaked in hank's solution (37 deg. C) to investigate the corrosion resistance. Magnesium alloy AZ31 with magnesium hydroxide coatings present superior corrosion resistance than untreated samples.

Magnesium and Space Flight

Science.gov (United States)

Smith, Scott M.; Zwart, Sara R.

2015-01-01

Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in 43 astronauts (34 male, 9 female; 47 ± 5 years old, mean ± SD) before, during, and after 4–6-month space missions. We also studied individuals participating in a ground analog of space flight (head-down-tilt bed rest; n = 27 (17 male, 10 female), 35 ± 7 years old). We evaluated serum concentration and 24-h urinary excretion of magnesium, along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-day space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4–6-month space missions. PMID:26670248

Magnesium and Space Flight

Directory of Open Access Journals (Sweden)

Scott M. Smith

2015-12-01

Full Text Available Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in 43 astronauts (34 male, 9 female; 47 ± 5 years old, mean ± SD before, during, and after 4–6-month space missions. We also studied individuals participating in a ground analog of space flight (head-down-tilt bed rest; n = 27 (17 male, 10 female, 35 ± 7 years old. We evaluated serum concentration and 24-h urinary excretion of magnesium, along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-day space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4–6-month space missions.

In vitro studies on magnesium uptake by rumen epithelium using magnesium-28

International Nuclear Information System (INIS)

Martens, H.; Harmeyer, J.; Breves, G.

1976-01-01

Magnesium-28 transfer across the rumen epithelium has been studied using surviving epithelia in an in vitro system. Net absorption of magnesium in the direction from lumen to blood could be observed as the result of two opposite unidirectional fluxes of different magnitude. Net uptake of magnesium occurred against an electrical potential difference, and was associated with the presence of an unaltered transmural potential difference in the mucosal tissue. Both the net transfer of magnesium and the transmural potential difference decreased during two hours of incubation. Unidirectional fluxes of magnesium and net efflux from the lumen were markedly reduced although not completely inhibited by the addition of ouabain (10 -4 mol/l). The findings suggest that the mechanism of magnesium absorption by the rumen epithelium can be considered as an active transport process, and that the rumen is the main area of magnesium absorption in the living animal. (author)

Magnesium, magnesium alloys, and magnesium composites

National Research Council Canada - National Science Library

Gupta, M; Sharon, Nai Mui Ling

2011-01-01

... of science, characteristics, and applications. It emphasizes the properties of magnesium-based composites and the effects of different types of reinforcements, from micron length to nanometer scale, on the properties of the resulting composites...

Magnesium Hydroxide

Science.gov (United States)

Magnesium hydroxide is used on a short-term basis to treat constipation.This medication is sometimes prescribed ... Magnesium hydroxide come as a tablet and liquid to take by mouth. It usually is taken as ...

Research Progress in Plasma arc welding of Magnesium Alloys and Magnesium Matrix Composites

Science.gov (United States)

Hui, Li; Yang, Zou; Yongbo, Li; Lei, Jiao; Ruijun, Hou

2017-11-01

Magnesium alloys and magnesium matrix composites by means of its excellent performance have wide application prospect in electronics, automotive, biotechnology, aerospace field, and welding technology has become a key of restricting its application. This paper describes the welding characteristics of magnesium, the obvious advantages in the application and the domestic and foreign research advance technology of plasma arc welding of magnesium, and summarizes the existing problems and development trends of plasma arc welding technology of magnesium.

FOCUS ON MAGNESIUM BASED DRUGS

Directory of Open Access Journals (Sweden)

I. I. Esenova

2011-01-01

Full Text Available Magnesium deficiency in the organism is one of the most common human deficiency states. The prevalence of magnesium deficiency is about 15%, and suboptimal magnesium level is observed more than in 30% of people in the general population. Clinical signs of hypomagnesaemia are observed in 40% of patients in general care hospitals, in 70% of patients - in intensive care units, and magnesium deficiency occurs in 90% of patients with acute coronary syndrome. Magnesium metabolic disorders in the organism accelerate significantly development of complications of coronary heart disease, hypertension, type 2 diabetes, asthma and a number of neurological and psychiatric diseases. The value of this macro in the body is well studied, and its daily need is identified depending on age and sex. It is known that magnesium intake with the food does not cover an organism need. It is a rationale for preventive and therapeutic use of magnesium based drugs in various diseases. Organic salts of magnesium are recommended for these purposes. Magnesium metabolic disorders, approaches to pharmacotherapeutic correction of magnesium deficiency, advantages of magnesium salts of orotic acid are reviewed.

Thermodynamic modelling of phase equilibrium in system Ti-B-Si-C, synthesis and phases composition of borides and carbides layers on titanic alloyVT-1 at electron beam treatment in vacuum

Science.gov (United States)

Smirnyagina, N. N.; Khaltanova, V. M.; Lapina, A. E.; Dasheev, D. E.

2017-01-01

Composite layers on the basis of carbides and borides the titan and silicon on titanic alloy VT-1 are generated at diffused saturation in vacuum. Formation in a composite of MAX phase Ti3SiC2 is shown. Thermodynamic research of phase equilibrium in systems Ti-Si-C and Ti-B-C in the conditions of high vacuum is executed. The thermodynamics, formation mechanisms of superfirm layers borides and carbides of the titan and silicon are investigated.

Magnesium Oxide

Science.gov (United States)

Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some people use it as ... one to four times daily depending on which brand is used and what condition you have. Follow ...

Magnesium motorcycle applications

International Nuclear Information System (INIS)

Jianyong Cao; Zonghe Zhang; Dongxia Xiang; Jun Wang

2005-01-01

Magnesium, the lightest engineering structural metal, has been comprehensively used in castings of aviation and aerospace, communication and transportation, and IT components. This paper introduced the history, advantages and difficulties of magnesium castings for motorcycle application as well as its application state in China. It also indicated the production situation of magnesium motorcycle components in CQMST and difficulties need to overcome for further development. (orig.)

Magnesium sulfate reduces formalin-induced orofacial pain in rats with normal magnesium serum levels.

Science.gov (United States)

Srebro, Dragana P; Vučković, Sonja M; Dožić, Ivan S; Dožić, Branko S; Savić Vujović, Katarina R; Milovanović, Aleksandar P; Karadžić, Branislav V; Prostran, Milica Š

2018-02-01

In humans, orofacial pain has a high prevalence and is often difficult to treat. Magnesium is an essential element in biological a system which controls the activity of many ion channels, neurotransmitters and enzymes. Magnesium produces an antinociceptive effect in neuropathic pain, while in inflammatory pain results are not consistent. We examined the effects of magnesium sulfate using the rat orofacial formalin test, a model of trigeminal pain. Male Wistar rats were injected with 1.5% formalin into the perinasal area, and the total time spent in pain-related behavior (face rubbing) was quantified. We also spectrophotometrically determined the concentration of magnesium and creatine kinase activity in blood serum. Magnesium sulfate administered subcutaneously (0.005-45mg/kg) produced significant antinociception in the second phase of the orofacial formalin test in rats at physiological serum concentration of magnesium. The effect was not dose-dependent. The maximum antinociceptive effect of magnesium sulfate was about 50% and was achieved at doses of 15 and 45mg/kg. Magnesium did not affect increase the levels of serum creatine kinase activity. Preemptive systemic administration of magnesium sulfate as the only drug can be used to prevent inflammatory pain in the orofacial region. Its analgesic effect is not associated with magnesium deficiency. Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Function of magnesium aluminate hydrate and magnesium nitrate ...

Indian Academy of Sciences (India)

MgO was added both as spinel (MgAl2O4) forming precursor i.e. magnesium aluminate hydrate, and magnesium nitrate. Sintering investigations were conducted in the temperature range 1500–1600°C with 2 h soaking. Structural study of sintered pellets was carried out by extensive XRD analysis. Scanning electron mode ...

Synthesis of molybdenum borides and molybdenum silicides in molten salts and their oxidation behavior in an air-water mixture

NARCIS (Netherlands)

Kuznetsov, S.A.; Kuznetsova, S.V.; Rebrov, E.V.; Mies, M.J.M.; Croon, de M.H.J.M.; Schouten, J.C.

2005-01-01

The formation of various coatings in molybdenum-boron and molybdenum-silicon systems was investigated. Boronizing and siliciding treatments were conducted in molten salts under inert gas atm. in the 850-1050 DegC temp. range for 7 h. The presence of boride (e.g. Mo2B, MoB, Mo2B5) and silicide

Magnesium compounds

Science.gov (United States)

Kramer, D.A.

2007-01-01

Seawater and natural brines accounted for about 52 percent of U.S. magnesium compounds production in 2006. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from sea-water by Premier Chemicals in Florida; from well brines in Michigan by Martin Marietta and Rohm and Haas; and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from brucite by Applied Chemical Magnesias in Texas, from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta and Rohm and Haas from their operations mentioned above. About 59 percent of the magnesium compounds consumed in the United States was used for refractories that are used mainly to line steelmaking furnaces. The remaining 41 percent was consumed in agricultural, chemical, construction, environmental and industrial applications.

Innovative Vacuum Distillation for Magnesium Recycling

Science.gov (United States)

Zhu, Tianbai; Li, Naiyi; Mei, Xiaoming; Yu, Alfred; Shang, Shixiang

Magnesium recycling now becomes a very important subject as magnesium consumption increases fast around the world. All commonly used magnesium die-casting alloys can be recycled and recovered to the primary metal quality. The recycled materials may be comprised of biscuits, sprues, runners, flash, overflows, dross, sludge, scrap parts, and old parts that are returned from service, An innovative magnesium recycle method, vacuum distillation, is developed and proved out to be able to recycle magnesium scraps, especially machining chips, oily magnesium, smelting sludge, dross or the mixture. With this process at a specific temperature and environment condition, magnesium in scraps can be gasified and then solidified to become crystal magnesium crown. This `recycled' magnesium crown is collected and used as the raw material of magnesium alloys. The experimental results show the vacuum distillation is a feasible and plausible method to recycle magnesium. Further, the cost analysis will be addressed in this paper.

INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

Directory of Open Access Journals (Sweden)

Berat Barıs BULDUM

2013-01-01

Full Text Available Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attractive to designers due to their low density, only two thirds that of aluminium and its alloys [1]. The element and its alloys take a big part of modern industry needs. Especially nowadays magnesium alloys are used in automotive and mechanical (trains and wagons manufacture, because of its lightness and other features. Magnesium and magnesium alloys are the easiest of all metals to machine, allowing machining operations at extremely high speed. All standard machining operations such as turning, drilling, milling, are commonly performed on magnesium parts.

Structural, electronic and thermal properties of super hard ternary boride, WAlB

Science.gov (United States)

Rajpoot, Priyanka; Rastogi, Anugya; Verma, U. P.

2018-04-01

A first principle study of the structural, electronic and thermal properties of Tungsten Aluminum Boride (WAlB) using full-potential linearized augmented plane wave (FP-LAPW) in the frame work of density function theory (DFT) have been calculated. The calculated equilibrium structural parameters are in excellent agreement with available experimental results. The calculated electronic band structure reveals that WAlB is metallic in nature. The quasi-harmonic Debye model is applied to study of the temperature and pressure effect on volume, Debye temperature, thermal expansion coefficient and specific heat at constant volume and constant pressure. To the best of our knowledge theoretical investigation of these properties of WAlB is reported for the first time.

PREFACE: The 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008)

Science.gov (United States)

Tanaka, Takaho

2009-07-01

This volume of Journal of Physics: Conference Series contains invited and contributed peer-reviewed papers that were presented at the 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008), which was held on 7-12 September 2008, at Kunibiki Messe, Matsue, Japan. This triennial symposium has a half-century long history starting from the 1st meeting in 1959 at Asbury Park, New Jersey. We were very pleased to organize ISBB 2008, which gathered chemists, physicists, materials scientists as well as diamond and high-pressure researchers. This meeting had a strong background in the boron-related Japanese research history, which includes the discovery of superconductivity in MgB2 and development of Nd-Fe-B hard magnets and of YB66 soft X-ray monochromator. The scope of ISBB 2008 spans both basic and applied interdisciplinary research that is centered on boron, borides and related materials, and the collection of articles defines the state of the art in research on these materials. The topics are centered on: 1. Preparation of new materials (single crystals, thin films, nanostructures, ceramics, etc) under normal or extreme conditions. 2. Crystal structure and chemical bonding (new crystal structures, nonstoichiometry, defects, clusters, quantum-chemical calculations). 3. Physical and chemical properties (band structure, phonon spectra, superconductivity; optical, electrical, magnetic, emissive, mechanical properties; phase diagrams, thermodynamics, catalytic activity, etc) in a wide range of temperatures and pressures. 4. Applications and prospects (thermoelectric converters, composites, ceramics, coatings, etc) There were a few discoveries of new materials, such as nanomaterials, and developments in applications. Many contributions were related to 4f heavy Fermion systems of rare-earth borides. Exotic mechanisms of magnetism and Kondo effects have been discussed, which may indicate another direction of development of boride. Two special sessions

Study of a portion of Al-Be-B system and boron effect on ABM-1 alloy properties

International Nuclear Information System (INIS)

Novoselova, A.V.; Molchanova, L.V.; Yatsenko, K.P.; Fridlyander, I.N.

1989-01-01

The phase composition of Al-Be-B system alloys, phase transformations and boron effect on magnesium-containing ABM-1 alloy properties are investigated. Depending on the composition and crystallization conditions, the following phases in the investigated alloys are determined: a beryllium-base phase, an aluminium-base phase and a phase on the base of borides. It is found that boron content growth up to 1% increases ultimate strength, which sharply decreases with the boron content rise up to 2% as a result of crystallization of coarse needle-like inclusions of beryllium boride. With the aluminium content decrease the boron amount in the alloy can be increased

Magnesium compounds

Science.gov (United States)

Kramer, D.A.

2012-01-01

Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

Magnesium-based implants: a mini-review.

Science.gov (United States)

Luthringer, Bérengère J C; Feyerabend, Frank; Willumeit-Römer, Regine

2014-01-01

The goal of this review is to bring to the attention of the readership of Magnesium Research another facet of the importance of magnesium, i.e. magnesium-based biomaterials. A concise history of biomaterials and magnesium are thus presented. In addition, historical and current, clinical magnesium-based applications are presented.

Thermo-emf of cermet films based on rare earth borides

International Nuclear Information System (INIS)

Islamgaliev, R.K.; Zyrin, A.V.; Shulishova, O.I.; Shcherbak, I.A

1987-01-01

Thermo-emf and electric conductivity of granulated films which contain a solid solution of europium and praseodymium borides Eu 0.5 Pr 0.5 B 6 as a conducting phase, and glass-crystal binder on the base of alummomagnesial fluosilicates as a dielectric phase are studied within the temperature range of 100-1100 K. Thermo-emf of films has a negative sign within the temperature range of 100-500 K and does not exceed 5 μkV/K according to the absolute value which is close to the value of the conducting phase thermo-emf. A negative sign and a small value of thermo-emf are indicative of the charge transfer in granulated films by electrons. Contribution of each of the components into the general thermo-emf is different at high temperatures in different temperature ranges and depends on the individual physico-chemical properties of the used materials

Ionized magnesium in plasma and erythrocytes for the assessment of low magnesium status in alcohol dependent patients.

Science.gov (United States)

Ordak, Michal; Maj-Zurawska, Magdalena; Matsumoto, Halina; Bujalska-Zadrozny, Magdalena; Kieres-Salomonski, Ilona; Nasierowski, Tadeusz; Muszynska, Elzbieta; Wojnar, Marcin

2017-09-01

Studies on the homeostasis of magnesium in alcohol-dependent patients have often been characterized by low hypomagnesemia detection rates. This may be due to the fact that the content of magnesium in blood serum constitutes only 1% of the average magnesium level within the human body. However, the concentration of ionized magnesium is more physiologically important and makes up 67% of the total magnesium within a human organism. There are no data concerning the determination of the ionized fraction of magnesium in patients addicted to alcohol and its influence on mental health status. This study included 100 alcohol-dependent patients and 50 healthy subjects. The free magnesium fraction was determined using the potentiometric method by means of using ion-selective electrodes. The total magnesium level was determined by using a biochemical Indiko Plus analyzer. In this study, different psychometric scales were applied. Our results confirm the usefulness of ionized magnesium concentrations in erythrocytes and plasma as a diagnostic parameter of low magnesium status in alcohol-dependent patients. The lower the concentration of ionized magnesium, the worse the quality of life an alcohol-dependent person might experience. In the case of total magnesium, no such correlation was determined. Copyright © 2017 Elsevier B.V. All rights reserved.

Choline Magnesium Trisalicylate

Science.gov (United States)

Choline magnesium trisalicylate is used to relieve the pain, tenderness, inflammation (swelling), and stiffness caused by arthritis and painful ... used to relieve pain and lower fever. Choline magnesium trisalicylate is in a class of nonsteroidal anti- ...

Combustion and extinction of magnesium fires

International Nuclear Information System (INIS)

Malet, J.C.; Duverger de Cuy, G.

1988-01-01

The studies made in France on magnesium combustion and extinguishing means are associated at the nuclear fuel of the graphite-gas reactor. Safety studies are made for ameliorate our knowledge on: - magnesium combustion - magnesium fire propagation - magnesium fire extinguishing [fr

Magnesium deficiency: What is our status

Science.gov (United States)

Low magnesium intake has been implicated in a broad range of cardiometabolic conditions, including diabetes, hypertension, and cardiovascular disease. Dietary magnesium and total body magnesium status have a widely-used but imperfect biomarker in serum magnesium. Despite serum magnesium’s limitation...

Structure-chemical and metallurgical investigations in boride- and boron nitride systems

International Nuclear Information System (INIS)

Smid, I.

1987-01-01

Thermodynamic phase equilibria in the systems (Ti, Zv, Hf)-B-N were determined in an isothermal cut at 1500 O C and 1 atm. The phase field separation is dominated by the high stability of the metal mononitrides and metal diborides. No ternery compounds were found. There are varying solubilities of B and N in the nitrides and borides. The system Cr-B-N was investigated at 1000 O C under 1 atm argon and vacuum, and at 1400 O C at 1 atm argon and 1 atm nitrogen. For the system Mn-B-N the phase field separation was determined at 900 O C under 1 atm Ar and under vacuum. The properties of hard metals with various binding phases and TiBr as hard constituents were investigated. 6 refs., 6 figs., 6 tabs. (qui)

Quantitative electron probe microanalysis of boron in binary borides

International Nuclear Information System (INIS)

Bastin, G.F.; Heijligers, H.J.M.

1986-01-01

Quantitative electron probe microanalysis has been performed in 27 binary borides in the range of 4-30 keV, both for the metals as well as for Boron. The procedures along which accurate intensity measurements for B-K α must be carried out are discussed in detail. A total of 196 k-ratios with respect to elemental standards for the metal X-ray lines and 180 k-ratios for B-K α relative to elemental Boron have been obtained. These data have been used to arrive at an improved parameterization for the φ(ρz) approach in matrix correction. The resulting new program (BAS861) was compared to 5 other current correction programs. At the same occasion the available set of mass absorption coefficients for Boron was tested on its consistency and better values suggested where necessary. Finally it is shown that the modified version of the Gaussian φ(ρz) approach (BAS861 program) is highly successful in the matrix correction for B-K α : a relative root-mean-square value of 6.30% was obtained. (Auth.)

Spider silk as a template for obtaining magnesium oxide and magnesium hydroxide fibers

Directory of Open Access Journals (Sweden)

Dmitrović Svetlana

2018-01-01

Full Text Available Spider silk fibers, collected from Pholcus Phalangioides spider were used as a template for obtaining magnesium oxide (MgO, periclase as well as magnesium hydroxide (Mg(OH2, brucite fibers. Magnesium oxide fibers were obtained in a simple manner by heat induced decomposition of magnesium salt (MgCl2 in the presence of the spider silk fibers, while magnesium hydroxide fibers were synthesized by hydration of MgO fibers at 50, 70 and 90 C, for 48 and 96 h. According to Scanning electron microscopy (SEM, dimensions of spider silk fibers determined the dimension of synthesized MgO fibers, while for Mg(OH2 fibers, the average diameter was increased with prolonging the hydration period. The surface of Mg(OH2 fibers was noticed to be covered with brucite in a form of plates. X-Ray diffraction (XRD analysis showed that MgO fibers were single-phased (the pure magnesium oxide fibers were obtained, while Mg(OH2 fibers were two- or single-phased brucite depending on incubation period, and/or incubation temperature. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45012

Magnesium Technology : Preface

NARCIS (Netherlands)

Sillekens, W.H.; Agnew, S.R.; Neelameggham, N.R.; Mathaudhu, S.N.

2011-01-01

The Magnesium Technology Symposium, which takes place every year at the TMS Annual Meeting & Exhibition, is one of the largest yearly gatherings of magnesium specialists in the world. Papers are presented in all aspects of the field, ranging from primary production to applications to recycling.

The Corrosion of Magnesium and of the Magnesium Aluminum Alloys Containing Manganese

Science.gov (United States)

Boyer, J A

1927-01-01

The extensive use of magnesium and its alloys in aircraft has been seriously handicapped by the uncertainties surrounding their resistance to corrosion. This problem has been given intense study by the American Magnesium Corporation and at the request of the Subcommittee on Materials for Aircraft of the National Advisory Committee for Aeronautics this report was prepared on the corrosion of magnesium. The tentative conclusions drawn from the experimental facts of this investigation are as follows: the overvoltage of pure magnesium is quite high. On immersion in salt water the metal corrodes with the liberation of hydrogen until the film of corrosion product lowers the potential to a critical value. When the potential reaches this value it no longer exceeds the theoretical hydrogen potential plus the overvoltage of the metal. Rapid corrosion consequently ceases. When aluminum is added, especially when in large amounts, the overvoltage is decreased and hydrogen plates out at a much lower potential than with pure magnesium. The addition of small amount of manganese raises the overvoltage back to practically that of pure metal, and the film is again negative.

On magnetic properties of thorium and uranium borides and Usub(1-x)Thsub(x)Bsub(4) solid solutions

International Nuclear Information System (INIS)

Chachkhiani, Z.B.; Chachkhiani, L.G.; Chechernikov, V.I.; Slovyanskikh, V.K.

1982-01-01

The dependence of magnetic susceptibility on temperature of UB 4 compound and Usub(1-x)Thsub(x)Bsub(4) alloy system in the 140-1300 K temperature range is investigated. It has been found that paramagnetic susceptibility does not obeys the Curie-Weiss law. The interpretation of experimental results is performed on the basis of Stoner model of collectivized electrons which permits also to explain the magnetic properites of other thorium and uranium borides

Photoluminescence of magnesium-associated color centers in LiF crystals implanted with magnesium ions

Science.gov (United States)

Nebogin, S. A.; Ivanov, N. A.; Bryukvina, L. I.; V. Shipitsin, N.; E. Rzhechitskii, A.; Papernyi, V. L.

2018-05-01

In the present paper, the effect of magnesium nanoparticles implanted in a LiF crystal on the optical properties of color centers is studied. The transmittance spectra and AFM images demonstrate effective formation of the color centers and magnesium nanoparticles in an implanted layer of ∼ 60-100 nm in thickness. Under thermal annealing, a periodical structure is formed on the surface of the crystal and in the implanted layer due to self-organization of the magnesium nanoparticles. Upon excitation by argon laser with a wavelength of 488 nm at 5 K, in a LiF crystal, implanted with magnesium ions as well as in heavily γ-irradiated LiF: Mg crystals, luminescence of the color centers at λmax = 640 nm with a zero-phonon line at 601.5 nm is observed. The interaction of magnesium nanoparticles and luminescing color centers in a layer implanted with magnesium ions has been revealed. It is shown that the luminescence intensity of the implanted layer at a wavelength of 640 nm is by more than two thousand times higher than that of a heavily γ-irradiated LiF: Mg crystal. The broadening of the zero-phonon line at 601.5 nm in the spectrum of the implanted layer indicates the interaction of the emitting quantum system with local field of the surface plasmons of magnesium nanoparticles. The focus of this work is to further optimize the processing parameters in a way to result in luminescence great enhancement of color centers by magnesium nanoparticles in LiF.

Magnesium oxychloride cement concrete

Indian Academy of Sciences (India)

TECS

exposure to water and salt attack by replacing 10% magnesium chloride solution by magnesium sulphate solution ... Having tremendous load bearing capacity, it can withstand .... retention coefficients for similar concrete compositions.

21 CFR 184.1443 - Magnesium sulfate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to crystallization...

Mineral resource of the month: magnesium

Science.gov (United States)

Kramer, Deborah A.

2012-01-01

Magnesium is the eighthmost abundant element in Earth’s crust, and the second-most abundant metal ion in seawater. Although magnesium is found in more than 60 minerals, only brucite, dolomite, magnesite and carnallite are commercially important for their magnesium content. Magnesium and its compounds also are recovered from seawater, brines found in lakes and wells, and bitterns (salts).

21 CFR 184.1431 - Magnesium oxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium oxide. 184.1431 Section 184.1431 Food and... Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No. 1309-48-4... powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide or carbonate...

21 CFR 184.1426 - Magnesium chloride.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... hydrochloric acid solution and crystallizing out magnesium chloride hexahydrate. (b) The ingredient meets the...

A Study on the Effect of the Boron Potential on the Mechanical Properties of the Borided Layers Obtained by Boron Diffusion at the Surface of AISI 316L Steel

Directory of Open Access Journals (Sweden)

E. Hernández-Sánchez

2014-01-01

Full Text Available The effect of the boron potential on the thickness and the mechanical properties of borided layers was evaluated. The boron potential was established by means of the available atoms of boron contained in a control volume inside a cylinder. The cylinders were manufactured from AISI 316L steel, and the boriding treatment was performed using the powder pack technique at a temperature of 1273 K over an exposure time of 6 h. Four different internal diameters of the cylinders were evaluated (3.17, 4.76, 6.35, and 7.93 mm. The mechanical properties were evaluated using the Berkovich instrumented indentation technique. The results showed a clear influence of the boron potential on the mechanical properties of the layers. The hardness of the layers was stablished in the range of 16.22 to 21.16 GPa. Young’s modulus values were stablished in the range of 255.96 to 341.37 GPa. Also the fracture toughness and brittleness of the layers reflected the influence of the boron potential supplied during the boriding process. Finally, the influence of the boron potential on the constant of parabolic growth (K was also established as a function of the inner diameter of the cylinders.

Lightweight Heat Pipes Made from Magnesium

Science.gov (United States)

Rosenfeld, John N.; Zarembo, Sergei N.; Eastman, G. Yale

2010-01-01

Magnesium has shown promise as a lighter-weight alternative to the aluminum alloys now used to make the main structural components of axially grooved heat pipes that contain ammonia as the working fluid. Magnesium heat-pipe structures can be fabricated by conventional processes that include extrusion, machining, welding, and bending. The thermal performances of magnesium heat pipes are the same as those of equal-sized aluminum heat pipes. However, by virtue of the lower mass density of magnesium, the magnesium heat pipes weigh 35 percent less. Conceived for use aboard spacecraft, magnesium heat pipes could also be attractive as heat-transfer devices in terrestrial applications in which minimization of weight is sought: examples include radio-communication equipment and laptop computers.

21 CFR 862.1495 - Magnesium test system.

Science.gov (United States)

2010-04-01

... magnesium levels in serum and plasma. Magnesium measurements are used in the diagnosis and treatment of hypomagnesemia (abnormally low plasma levels of magnesium) and hypermagnesemia (abnormally high plasma levels of magnesium). (b) Classification. Class I. ...

Radioactive 210Po in magnesium supplements

International Nuclear Information System (INIS)

Struminska-Parulska, Dagmara Ida

2016-01-01

The aim of this pioneer study was to determine polonium 210 Po in the most popular magnesium supplements in Poland and estimate the possible related dose assessment to the consumers. The analyzed magnesium pharmaceutics contained organic or inorganic magnesium compounds; some from natural sources. The objectives of this research were to investigate the naturally occurring 210 Po activity concentrations in magnesium supplements, find the correlations between 210 Po concentration in medicament and magnesium chemical form, and calculate the effective radiation dose connected to analyzed magnesium supplement consumption. The highest 210 Po activity concentrations were determined in mineral tablets made from sedimentary rocks, namely dolomite - 3.84 ± 0.15 mBq g -1 (sample Mg17). The highest annual radiation dose from 210 Po taken with 1 tablet of magnesium supplement per day or with 400 mg of pure Mg daily would come from sample Mg17 (dolomite) - 1.35 ± 0.5 and 8.44 ± 0.33 μSv year -1 respectively.

Alkoxide-based magnesium electrolyte compositions for magnesium batteries

Science.gov (United States)

Dai, Sheng; Sun, Xiao-Guang; Liao, Chen; Guo, Bingkun

2018-01-30

Alkoxide magnesium halide compounds having the formula: RO--Mg--X (1) wherein R is a saturated or unsaturated hydrocarbon group that is unsubstituted, or alternatively, substituted with one or more heteroatom linkers and/or one or more heteroatom-containing groups comprising at least one heteroatom selected from fluorine, nitrogen, oxygen, sulfur, and silicon; and X is a halide atom. Also described are electrolyte compositions containing a compound of Formula (1) in a suitable polar aprotic or ionic solvent, as well as magnesium batteries in which such electrolytes are incorporated.

Corrosion resistance of multilayered magnesium phosphate/magnesium hydroxide film formed on magnesium alloy using steam-curing assisted chemical conversion method

International Nuclear Information System (INIS)

Ishizaki, Takahiro; Kudo, Ruriko; Omi, Takeshi; Teshima, Katsuya; Sonoda, Tsutomu; Shigematsu, Ichinori; Sakamoto, Michiru

2012-01-01

Anticorrosive multilayered films were successfully prepared on magnesium alloy AZ31 by chemical conversion treatment, followed by steam curing treatment. The crystal structures, chemical composition, surface morphologies, chemical bonding states of the film was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscope (FE-SEM) measurements. All the films had thicknesses of ranging from 24 to 32 μm. The film had two layers that were composed of crystalline NH 4 MgPO 4 ·H 2 O, Mg 2 PO 4 OH·3H 2 O, Mg(OH) 2 and amorphous MgO. The outer layers include magnesium, oxygen, and phosphorous, and the inner layers include magnesium and oxygen. The corrosion resistant performances of the multilayered films in 5 wt% NaCl aqueous solution were investigated by electrochemical and gravimetric measurements. The potentiodynamic polarization curves revealed that the corrosion current density (j corr ) of all the film coated magnesium alloys decreased by more than four orders of magnitude as compared to that of the bare magnesium alloy, indicating that all the films had an inhibiting effect of corrosion reaction. Gravimetric measurements showed that the average corrosion rates obtained from the weight loss rates were estimated to be in the ranges of ca. 0.085–0.129 mm/y. American Society for Testing and Materials (ASTM) standard D 3359-02 cross cut tape test revealed that the adhesion of our anticorrosive multilayered film to the magnesium alloy surface was very good.

Nanostructured magnesium increases bone cell density.

Science.gov (United States)

Weng, Lucy; Webster, Thomas J

2012-12-07

Magnesium has attracted some attention in orthopedics due to its biodegradability and mechanical properties. Since magnesium is an essential natural mineral for bone growth, it can be expected that as a biomaterial, it would support bone formation. However, upon degradation in the body, magnesium releases OH(-) which results in an alkaline pH that can be detrimental to cell density (for example, osteoblasts or bone forming cells). For this reason, modification of magnesium may be necessary to compensate for such detrimental effects to cells. This study created biologically inspired nanoscale surface features on magnesium by soaking magnesium in various concentrations of NaOH (from 1 to 10 N) and for various periods of time (from 10 to 30 min). The results provided the first evidence of increased roughness, surface energy, and consequently greater osteoblast adhesion, after 4 h as well as density up to 7 days on magnesium treated with any concentration of NaOH for any length of time compared to untreated controls. For these reasons, this study suggests that soaking magnesium in NaOH could be an inexpensive, simple and effective manner to promote osteoblast functions for numerous orthopedic applications and, thus, should be further studied.

Calcium and magnesium determination

International Nuclear Information System (INIS)

Bhattacharya, S.K.

1982-01-01

The roles of calcium and magnesium in human health and disease have been extensively studied. Calcium and magnesium have been determined in biological specimens by atomic absorption spectroscopy using stiochiometric nitrous oxide-acetylene flame

A SEARCH FOR MAGNESIUM IN EUROPA'S ATMOSPHERE

International Nuclear Information System (INIS)

Hörst, S. M.; Brown, M. E.

2013-01-01

Europa's tenuous atmosphere results from sputtering of the surface. The trace element composition of its atmosphere is therefore related to the composition of Europa's surface. Magnesium salts are often invoked to explain Galileo Near Infrared Mapping Spectrometer spectra of Europa's surface, thus magnesium may be present in Europa's atmosphere. We have searched for magnesium emission in the Hubble Space Telescope Faint Object Spectrograph archival spectra of Europa's atmosphere. Magnesium was not detected and we calculate an upper limit on the magnesium column abundance. This upper limit indicates that either Europa's surface is depleted in magnesium relative to sodium and potassium, or magnesium is not sputtered as efficiently resulting in a relative depletion in its atmosphere.

Corrosion of magnesium and some magnesium alloys in gas cooled reactors

International Nuclear Information System (INIS)

Caillat, R.; Darras, R.

1958-01-01

The results of corrosion tests on magnesium and some magnesium alloys (Mg-Zr and Mg-Zr-Zn) in moist air (like G1 reactor) and in CO 2 : (like G2, G3, EDF1 reactors) are reported. The maximum temperature for exposure of magnesium to moist air without any risk of corrosion is 350 deg. C. Indeed, the oxidation rate follows a linear law above 350 deg. C although it reaches a constant level and keeps on very low under 350 deg. C. However, as far as corrosion is concerned this temperature limit can be raised up to 500 deg. C if moist air is very slightly charged with fluorinated compounds. Under pressure of CO 2 , these three materials oxidate much more slowly even if 500 deg. C is reached. The higher is the temperature, the higher is the constant level of the weight increase and the quicker is reached this one. However, Mg-Zr alloy behaves quite better than pure magnesium and especially than Mg-Zr-Zn alloy. (author) [fr

Nanostructured magnesium increases bone cell density

International Nuclear Information System (INIS)

Weng, Lucy; Webster, Thomas J

2012-01-01

Magnesium has attracted some attention in orthopedics due to its biodegradability and mechanical properties. Since magnesium is an essential natural mineral for bone growth, it can be expected that as a biomaterial, it would support bone formation. However, upon degradation in the body, magnesium releases OH − which results in an alkaline pH that can be detrimental to cell density (for example, osteoblasts or bone forming cells). For this reason, modification of magnesium may be necessary to compensate for such detrimental effects to cells. This study created biologically inspired nanoscale surface features on magnesium by soaking magnesium in various concentrations of NaOH (from 1 to 10 N) and for various periods of time (from 10 to 30 min). The results provided the first evidence of increased roughness, surface energy, and consequently greater osteoblast adhesion, after 4 h as well as density up to 7 days on magnesium treated with any concentration of NaOH for any length of time compared to untreated controls. For these reasons, this study suggests that soaking magnesium in NaOH could be an inexpensive, simple and effective manner to promote osteoblast functions for numerous orthopedic applications and, thus, should be further studied. (paper)

Nutrition and magnesium absorption

NARCIS (Netherlands)

Brink, E.J.

1992-01-01

The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true

New ternary transition metal borides containing uranium and rare earth elements

International Nuclear Information System (INIS)

Rogl, P.; Delong, L.

1983-01-01

The new ternary actinide metal diborides U 2 MoB 6 , U 2 ReB 6 , U 2 OsB 6 , URuB 4 and UOsB 4 were prepared and found to crystallize with either the Y 2 ReB 6 or the ThMoB 4 type of structure. LuRuB 4 and LuOsB 4 crystallize with the YCrB 4 type of structure. In a ternary series of solid solutions YRh 3 Bsub(1-x) (0 0 C), boron was found to stabilize a Cu 3 Au type of structure. The superconductivity of the new uranium compounds and of a series of ternary transition metal borides was investigated; no superconductivity was observed for temperatures as low at 1.3-1.5 K. The cubic perovskite or filled Cu 3 Au structure is discussed as a type which is very unfavorable for the occurrence of superconductivity. (Auth.)

A superconducting battery material: Lithium gold boride (LiAu3B)

Science.gov (United States)

Aydin, Sezgin; Şimşek, Mehmet

2018-04-01

The superconducting and potential cathode material properties of ternary boride of LiAu3B have been investigated by density functional first principles. The Li-concentration effects on the actual electronic and structural properties, namely the properties of LixAu9B3 (x = 0, 1, 2) sub-systems are studied. It is remarkably shown that the existence of Li-atoms has no considerable effect on the structural properties of Au-B skeleton in LiAu3B. Then, it can be offered as a potential cathode material for Li-ion batteries with the very small volume deviation of 0.42%, and the suitable average open circuit voltage of ∼1.30 V. Furthermore, the vibrational and superconducting properties such as electron-phonon coupling constant (λ) and critical temperature (Tc) of LiAu3B are studied. The calculated results suggest that LiAu3B should be a superconductor with Tc ∼5.8 K, also.

Magnesium-DNA interactions and the possible relation of magnesium to carcinogenesis. Irradiation and free radicals.

Science.gov (United States)

Anastassopoulou, J; Theophanides, T

2002-04-01

Magnesium deficiency causes renal complications. The appearance of several diseases is related to its depletion in the human body. In radiotherapy, as well as in chemotherapy, especially in treatment of cancers with cis-platinum, hypomagnesaemia is observed. The site effects of chemotherapy that are due to hypomagnesaemia are decreased using Mg supplements. The role of magnesium in DNA stabilization is concentration dependent. At high concentrations there is an accumulation of Mg binding, which induces conformational changes leading to Z-DNA, while at low concentration there is deficiency and destabilization of DNA. The biological and clinical consequences of abnormal concentrations are DNA cleavage leading to diseases and cancer. Carcinogenesis and cell growth are also magnesium-ion concentration dependent. Several reports point out that the interaction of magnesium in the presence of other metal ions showed that there is synergism with Li and Mn, but there is magnesium antagonism in DNA binding with the essential metal ions in the order: Zn>Mg>Ca. In the case of toxic metals such as Cd, Ga and Ni there is also antagonism for DNA binding. It was found from radiolysis of deaerated aqueous solutions of the nucleoside 5'-guanosine monophosphate (5'-GMP) in the presence as well as in the absence of magnesium ions that, although the addition of hydroxyl radicals (*OH) has been increased by 2-fold, the opening of the imidazole ring of the guanine base was prevented. This effect was due to the binding of Mg2+ ions to N7 site of the molecule by stabilizing the five-member ring imitating cis-platinum. It was also observed using Fourier Transform Infrared spectroscopy, Raman spectroscopy and Fast Atom Bombardment mass spectrometry that *OH radicals subtract H atoms from the C1', C4' and C5' sites of the nucleotide. Irradiation of 5'-GMP in the presence of oxygen (2.5 x 10(-4) M) shows that magnesium is released from the complex. There is spectroscopic evidence that

Porous bioresorbable magnesium as bone substitute

Energy Technology Data Exchange (ETDEWEB)

Wen, C.E.; Yamada, Y.; Shimojima, K.; Chino, Y.; Hosokawa, H.; Mabuchi, M. [Inst. for Structural and Engineering Materials, National Inst. of Advanced Industrial Science and Technology, Nagoya (Japan)

2003-07-01

Recently magnesium has been recognized as a very promising biomaterial for bone substitutes because of its excellent properties of biocompatibility, biodegradability and bioresorbability. In the present study, magnesium foams were fabricated by using a powder metallurgical process. Scanning electron microscopy equipped with energy dispersive X-ray spectrometer (EDS) and compressive tester were used to characterize the porous magnesium. Results show that the Young's modulus and the peak stress of the porous magnesium increase with decreasing porosity and pore size. This study suggests that the mechanical properties of the porous magnesium with the low porosity of 35% and/or with the small pore size of about 70 {mu}m are close to those of human cancellous bones. (orig.)

Small for Gestational Age and Magnesium: Intrauterine magnesium deficiency may induce metabolic syndrome in later life

Directory of Open Access Journals (Sweden)

Junji Takaya

2015-12-01

Full Text Available Magnesium deficiency during pregnancy as a result of insufficient or low intake of magnesium is common in developing and developed countries. Previous reports have shown that intracellular magnesium of cord blood platelets is lower among small for gestational age (SGA groups than that of appropriate for gestational age (AGA groups, suggesting that intrauterine magnesium deficiency may result in SGA. Additionally, the risk of adult-onset diseases such as insulin resistance syndrome is greater among children whose mothers were malnourished during pregnancy, and who consequently had a low birth weight. In a number of animal models, poor nutrition during pregnancy leads to offspring that exhibit pathophysiological changes similar to human diseases. The offspring of pregnant rats fed a magensium restricted diet have developed hypermethylation in the hepatic 11β-hydroxysteroid dehydrogenase-2 promoter. These findings indicate that maternal magnesium deficiencies during pregnancy influence regulation of non-imprinted genes by altering the epigenetic regulation of gene expression, thereby inducing different metabolic phenotypes. Magnesium deficiency during pregnancy may be responsible for not only maternal and fetal nutritional problems, but also lifelong consequences that affect the offspring throughout their life. Epidemiological, clinical, and basic research on the effects of magnesium deficiency now indicates underlying mechanisms, especially epigenetic processes.

Magnesium in Prevention and Therapy

Science.gov (United States)

Gröber, Uwe; Schmidt, Joachim; Kisters, Klaus

2015-01-01

Magnesium is the fourth most abundant mineral in the body. It has been recognized as a cofactor for more than 300 enzymatic reactions, where it is crucial for adenosine triphosphate (ATP) metabolism. Magnesium is required for DNA and RNA synthesis, reproduction, and protein synthesis. Moreover, magnesium is essential for the regulation of muscular contraction, blood pressure, insulin metabolism, cardiac excitability, vasomotor tone, nerve transmission and neuromuscular conduction. Imbalances in magnesium status—primarily hypomagnesemia as it is seen more common than hypermagnesemia—might result in unwanted neuromuscular, cardiac or nervous disorders. Based on magnesium’s many functions within the human body, it plays an important role in prevention and treatment of many diseases. Low levels of magnesium have been associated with a number of chronic diseases, such as Alzheimer’s disease, insulin resistance and type-2 diabetes mellitus, hypertension, cardiovascular disease (e.g., stroke), migraine headaches, and attention deficit hyperactivity disorder (ADHD). PMID:26404370

Corrosion of Magnesium in Multimaterial System

Energy Technology Data Exchange (ETDEWEB)

Joshi, Vineet V.; Agnew, Sean

2017-08-16

The TMS Magnesium Committee has been actively involved in presenting cutting-edge research and development and the latest trends related to magnesium and its alloys to industry and academia. Topics including magnesium alloy development, applications, mechanism of deformation and corrosion, thermomechanical processing, modelling, etc. have been captured year after year through the Magnesium Technology symposium and conference proceedings at TMS and through special topics in JOM. Every year, based on the unanimous endorsement from the industry and academia, a topic is selected to address the latest developments within this subject in JOM. In continuation with last year’s coverage of Advances and Achievements in In-Situ Analysis of Corrosions and Structure–Property Relationship in Mg Alloys,[1] this year’s topic focuses on the Corrosion of Magnesium in Multimaterial Systems. Magnesium, the lightest of all the structural materials, has garnered much interest in the transportation, electronics packaging, defense equipments and industries alike and are more commonly being incorporated in multimaterial design concepts.[2-4] However, the application of the same is limited due to its highly corrosive nature, and understanding and mitigating the corrosion of magnesium has been a major research challenge.

The reference range of serum, plasma and erythrocyte magnesium

Directory of Open Access Journals (Sweden)

Suzanna Immanuel

2006-12-01

Full Text Available The interest in the clinical importance of serum magnesium level has just recently begun with the analysis and findings of abnormal magnesium level in cardiovascular, metabolic and neuromuscular disorder. Although the serum level does not reflect the body magnesium level, but currently, only serum magnesium determination is widely used. Erythrocyte magnesium is considered more sensitive than serum magnesium as it reflects intracellular magnesium status. According to NCCLS (National Committee for Clinical Laboratory Standards every laboratory is recommended to have its own reference range for the tests it performs, including magnesium determination. The reference range obtained is appropriate for the population and affected by the method and technique. This study aimed to find the reference range of serum and plasma magnesium and also intracellular magnesium i.e. erythrocyte magnesium by direct method, and compare the results of serum and plasma magnesium. Blood was taken from 114-blood donor from Unit Transfusi Darah Daerah (UTDD Budhyarto Palang Merah Indonesia (PMI DKI Jakarta, consisted of 57 male and 57 female, aged 17 – 65 years, clinically healthy according to PMI donor criteria. Blood was taken from blood set, collected into 4 ml vacuum tube without anticoagulant for serum magnesium determination and 3 ml vacuum tube with lithium heparin for determination of erythrocyte and plasma magnesium Determination of magnesium level was performed with clinical chemistry auto analyzer Hitachi 912 by Xylidil Blue method colorimetrically. This study showed no significant difference between serum and heparinized plasma extra cellular magnesium. The reference range for serum or plasma magnesium was 1.30 – 2.00 mEq/L and for erythrocyte magnesium was 4.46 - 7.10 mEq/L. (Med J Indones 2006; 15:229-35Keywords: Reference range, extracellular magnesium, intracellular magnesium

Magnesium Tube Hydroforming

International Nuclear Information System (INIS)

Liewald, M.; Pop, R.; Wagner, S.

2007-01-01

Magnesium alloys can be considered as alternative materials towards achieving light weight structures with high material stiffness. The formability of two magnesium alloys, viz. AZ31 and ZM21 has been experimentally tested using the IHP forming process. A new die set up for hot IHP forming has been designed and the process experimentally investigated for temperatures up to 400 deg. C. Both alloys exhibit an increase in formability with increasing forming temperature. The effect of annealing time on materials forming properties shows a fine grained structure for sufficient annealing times as well as deterioration with a large increase at the same time. The IHP process has also been used to demonstrate practicability and feasibility for real parts from manufacture a technology demonstrator part using the magnesium alloy ZM21

Magnesium-phosphate-glass cements with ceramic-type properties

Science.gov (United States)

Sugama, T.; Kukacka, L.E.

1982-09-23

Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate, exhibits rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

Magnesium phosphate glass cements with ceramic-type properties

Science.gov (United States)

Sugama, Toshifumi; Kukacka, Lawrence E.

1984-03-13

Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate exhibiting rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

Magnesium deficiency and increased inflammation: current perspectives

Directory of Open Access Journals (Sweden)

Nielsen FH

2018-01-01

Full Text Available Forrest H Nielsen Research Nutritionist Consultant, Grand Forks, ND, USA Abstract: Animal studies have shown that magnesium deficiency induces an inflammatory response that results in leukocyte and macrophage activation, release of inflammatory cytokines and acute-phase proteins, and excessive production of free radicals. Animal and in vitro studies indicate that the primary mechanism through which magnesium deficiency has this effect is through increasing cellular Ca2+, which is the signal that results in the priming of cells to give the inflammatory response. Primary pro-inflammatory cytokines such as tumor necrosis factor-α and interleukin (IL-1; the messenger cytokine IL-6; cytokine responders E-selectin, intracellular adhesion molecule-1 and vascular cell adhesion molecule-1; and acute-phase reactants C-reactive protein and fibrinogen have been determined to associate magnesium deficiency with chronic low-grade inflammation (inflammatory stress. When magnesium dietary intake, supplementation, and/or serum concentration suggest/s the presence of magnesium deficiency, it often is associated with low-grade inflammation and/or with pathological conditions for which inflammatory stress is considered a risk factor. When magnesium intake, supplementation, and/or serum concentration suggest/s an adequate status, magnesium generally has not been found to significantly affect markers of chronic low-grade inflammation or chronic disease. The consistency of these findings can be modified by other nutritional and metabolic factors that affect inflammatory and oxidative stress. In spite of this, findings to date provide convincing evidence that magnesium deficiency is a significant contributor to chronic low-grade inflammation that is a risk factor for a variety of pathological conditions such as cardiovascular disease, hypertension, and diabetes. Because magnesium deficiency commonly occurs in countries where foods rich in magnesium are not consumed in

Effect of Magnesium Hydride on the Corrosion Behavior of Pure Magnesium in 0.1 M NaCl Solution

OpenAIRE

Xu, Shanna; Dong, Junhua; Ke, Wei

2010-01-01

The effect of magnesium hydride on the corrosion behavior of pure magnesium in 0.1 M NaCl solution was investigated using the gas collection method, potentiostatic current decay test, and in situ Raman spectrum. The formation of magnesium hydride (MgH2, Mg2H4) was observed at the cathodic region. Applying anodic potential leads to decomposition of magnesium hydride. Magnesium hydride plays an important role on the negative difference effect (NDE) in both the cathodic and anodic regions.

Corrosion and protection of magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Ghali, E. [Laval Univ., Quebec City, PQ (Canada). Dept. of Mining and Metallurgy

2000-07-01

The oxide film on magnesium offers considerable surface protection in rural and some industrial environments and the corrosion rate lies between that of aluminum and low carbon steels. Galvanic coupling of magnesium alloys, high impurity content such as Ni, Fe, Cu and surface contamination are detrimental for corrosion resistance of magnesium alloys. Alloying elements can form secondary particles which are noble to the Mg matrix, thereby facilitating corrosion, or enrich the corrosion product thereby possibly inhibiting the corrosion rate. Bimetallic corrosion resistance can be increased by fluxless melt protection, choice of compatible alloys, insulating materials, and new high-purity alloys. Magnesium is relatively insensible to oxygen concentration. Pitting, corrosion in the crevices, filiform corrosion are observed. Granular corrosion of magnesium alloys is possible due to the cathodic grain-boundary constituent. More homogeneous microstructures tend to improve corrosion resistance. Under fatigue loading conditions, microcrack initiation in Mg alloys is related to slip in preferentially oriented grains. Coating that exclude the corrosive environments can provide the primary defense against corrosion fatigue. Magnesium alloys that contain neither aluminum nor zinc are the most SCC resistant. Compressive surface residual stresses as that created by short peening increase SCC resistance. Cathodic polarization or cladding with a SCC resistant sheet alloy are good alternatives. Effective corrosion prevention for magnesium alloy components and assemblies should start at the design stage. Selective surface preparation, chemical treatment and coatings are recommended. Oil application, wax coating, anodizing, electroplating, and painting are possible alternatives. Recently, it is found that a magnesium hydride layer, created on the magnesium surface by cathodic charging in aqueous solution is a good base for painting. (orig.)

Effect of Magnesium Hydride on the Corrosion Behavior of Pure Magnesium in 0.1 M NaCl Solution

Directory of Open Access Journals (Sweden)

Shanna Xu

2010-01-01

Full Text Available The effect of magnesium hydride on the corrosion behavior of pure magnesium in 0.1 M NaCl solution was investigated using the gas collection method, potentiostatic current decay test, and in situ Raman spectrum. The formation of magnesium hydride (MgH2, Mg2H4 was observed at the cathodic region. Applying anodic potential leads to decomposition of magnesium hydride. Magnesium hydride plays an important role on the negative difference effect (NDE in both the cathodic and anodic regions.

21 CFR 582.5431 - Magnesium oxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.5431 Section 582.5431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

21 CFR 582.1431 - Magnesium oxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance is...

21 CFR 582.5443 - Magnesium sulfate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium sulfate. 582.5443 Section 582.5443 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5443 Magnesium sulfate. (a) Product. Magnesium sulfate. (b) Conditions of use. This...

Imparting passivity to vapor deposited magnesium alloys

Science.gov (United States)

Wolfe, Ryan C.

Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread implementation of magnesium alloys is currently hindered by their relatively poor corrosion resistance. The objective of this research dissertation is to develop a scientific basis for the creation of a corrosion resistant magnesium alloy. The corrosion resistance of magnesium alloys is affected by several interrelated factors. Among these are alloying, microstructure, impurities, galvanic corrosion effects, and service conditions, among others. Alloying and modification of the microstructure are primary approaches to controlling corrosion. Furthermore, nonequilibrium alloying of magnesium via physical vapor deposition allows for the formation of single-phase magnesium alloys with supersaturated concentrations of passivity-enhancing elements. The microstructure and surface morphology is also modifiable during physical vapor deposition through the variation of evaporation power, pressure, temperature, ion bombardment, and the source-to-substrate distance. Aluminum, titanium, yttrium, and zirconium were initially chosen as candidates likely to impart passivity on vapor deposited magnesium alloys. Prior to this research, alloys of this type have never before been produced, much less studied. All of these metals were observed to afford some degree of corrosion resistance to magnesium. Due to the especially promising results from nonequilibrium alloying of magnesium with yttrium and titanium, the ternary magnesium-yttrium-titanium system was investigated in depth. While all of the alloys are lustrous, surface morphology is observed under the scanning

Separation of magnesium from magnesium chloride and zirconium and/or hafnium subchlorides in the production of zirconium and/or hafnium sponge metal

International Nuclear Information System (INIS)

Abodishish, H.A.M.; Adams, R.J.; Kearl, S.R.

1992-01-01

This patent describes the producing of a refractory metal wherein a sponge refractory metal is produced as an intermediate product by the use of magnesium with the incidental production of magnesium chloride, and wherein residual magnesium is separated from the magnesium chloride and from refractory metal to a vacuum distillation step which fractionally distills the magnesium, the magnesium chloride, and the metal sub-chlorides; the steps of: recovering fractionally distilled vapors of magnesium chloride and metal sub-chlorides from a sponge refractory metal; separately condensing the vapors as separately recovered; and recycling the separately recovered magnesium at a purity of at least about 96%

Assessment of serum magnesium levels and its outcome in neonates of eclamptic mothers treated with low-dose magnesium sulfate regimen

Science.gov (United States)

Das, Monalisa; Chaudhuri, Patralekha Ray; Mondal, Badal C.; Mitra, Sukumar; Bandyopadhyay, Debasmita; Pramanik, Sushobhan

2015-01-01

Objectives: Magnesium historically has been used for treatment and/or prevention of eclampsia. Considering the low body mass index of Indian women, a low-dose magnesium sulfate regime has been introduced by some authors. Increased blood levels of magnesium in neonates is associated with increased still birth, early neonatal death, birth asphyxia, bradycardia, hypotonia, gastrointestinal hypomotility. The objective of this study was to assess safety of low-dose magnesium sulfate regimen in neonates of eclamptic mothers treated with this regimen. Materials and Methods: This was a cross-sectional observational study of 100 eclampsia patients and their neonates. Loading dose and maintenance doses of magnesium sulfate were administered to patients by combination of intravenous and intramuscular routes. Maternal serum and cord blood magnesium levels were estimated. Neonatal outcome was assessed. Results: Bradycardia was observed in 18 (19.15%) of the neonates, 16 (17.02%) of the neonates were diagnosed with hypotonia. Pearson Correlation Coefficient showed Apgar scores decreased with increase in cord blood magnesium levels. Unpaired t-test showed lower Apgar scores with increasing dose of magnesium sulfate. The Chi-square/Fisher's exact test showed significant increase in hypotonia, birth asphyxia, intubation in delivery room, Neonatal Intensive Care Unit (NICU) care requirement, with increasing dose of magnesium sulfate. (P ≤ 0.05). Conclusion: Several neonatal complications are significantly related to increasing serum magnesium levels. Overall, the low-dose magnesium sulfate regimen was safe in the management of eclamptic mothers, without toxicity to their neonates. PMID:26600638

Improved cytotoxicity testing of magnesium materials

Energy Technology Data Exchange (ETDEWEB)

Fischer, Janine [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Department for Structural Research on Macromolecules, Max-Planck Str. 1, D - 21502 Geesthacht (Germany); Proefrock, Daniel [Helmholtz-Zentrum Geesthacht, Institute for Coastal Research, Department for Marine Bioanalytical Chemistry, Max-Planck Str. 1, D - 21502 Geesthacht (Germany); Hort, Norbert [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Department for Magnesium Processing, Max-Planck Str. 1, D - 21502 Geesthacht (Germany); Willumeit, Regine; Feyerabend, Frank [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Department for Structural Research on Macromolecules, Max-Planck Str. 1, D - 21502 Geesthacht (Germany)

2011-06-25

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.

Improved cytotoxicity testing of magnesium materials

International Nuclear Information System (INIS)

Fischer, Janine; Proefrock, Daniel; Hort, Norbert; Willumeit, Regine; Feyerabend, Frank

2011-01-01

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.

On the ionization of interstellar magnesium

International Nuclear Information System (INIS)

Gurzadyan, G.A.

1977-01-01

It has been shown that two concentric ionization zones of interstellar magnesium must exist around each star: internal, with a radius coinciding with that of the zone of hydrogen ionization Ssub(H); and external, with a radius greater than Ssub(H), by one order. Unlike interstellar hydrogen, interstellar magnesium is ionized throughout the Galaxy. It also transpires that the ionizing radiation of ordinary hot stars cannot provide for the observed high degree of ionization of interstellar magnesium. The discrepance can be eliminated by assuming the existence of circumstellar clouds or additional ionization sources of interstellar magnesium (X-ray background radiation, high-energy particles, etc.). Stars of the B5 and BO class play the main role in the formation of ionization zones of interstellar magnesium; the contribution of O class stars is negligible (<1%). (Auth.)

Magnesium balances and 28Mg studies in man

International Nuclear Information System (INIS)

Spencer, H.; Schwartz, R.; Osis, D.

1988-01-01

The intestinal absorption of magnesium was determined under strictly controlled dietary conditions in patients with normal renal function and also in patients with chronic renal failure. The average net absorption of magnesium of patients with normal renal function, expressed as percent of the magnesium intake, was 48.5%, while that of patients with chronic renal failure was significantly lower, 17%. Increasing the calcium intake from a low calcium intake of 200 mg/day to different higher intake levels up to 2000 mg/day did not change the magnesium balance nor the net absorption of magnesium of both types of patients. The lack of effect of the higher calcium intake on the absorption of magnesium was confirmed in 28 Mg studies in which an oral dose of 28 Mg, as the chloride, was given. The excretion of the absorbed magnesium into the intestine, the endogenous fecal magnesium, was low. Also, increasing the phosphorus intake up to 2000 mg/day in subjects with normal renal function did not affect the magnesium balance, regardless of the calcium intake

Aluminum Hydroxide and Magnesium Hydroxide

Science.gov (United States)

Aluminum Hydroxide, Magnesium Hydroxide are antacids used together to relieve heartburn, acid indigestion, and upset stomach. They ... They combine with stomach acid and neutralize it. Aluminum Hydroxide, Magnesium Hydroxide are available without a prescription. ...

Serum magnesium levels in patients with pre-eclampsia and eclampsia with different regimens of magnesium sulphate

Directory of Open Access Journals (Sweden)

Arpita Singh

2013-01-01

Full Text Available Background Pre-eclampsia and the subsequent eclampsia account for a common cause of maternal mortality worldwide and efforts aimed at reducing its menace are vital. Objective To estimate the serum magnesium levels in pre-eclampsia and eclampsia and to study the effect of using different regimens of magnesium sulphate. Methods 70 cases of pre-eclampsia and eclampsia and 35 normal pregnant women as controls were studied. Serum magnesium levels were estimated using Atomic Absorption Spectrophotometer (Model AAS-4139 at baseline and at frequent intervals during gestation and the overall parameters were meticulously observed. Results Majority(60%ofstudiedcaseswasnulliparawithgestationageof36-40 weeks. Statistically significant reduction of mean diastolic blood pressure and protein-urea was observed after using both intramuscular and intravenous regimens of magnesium sulphate. Mean initial serum magnesium level (mg/dl±SD was 1.81±0.58 in group A,1.55±0.41 in group B and 1.49±0.41 in group C. Mean serum magnesium levels during first 4 hours after therapy were statistically significant between intramuscular and intravenous regimen groups while same were statistically insignificant at 8,12,16,24 and 32 hours. Besides, few minor side effects including headache, vomiting, reduced tendon reflexes and thrombocytopenia, no severe side effects and no maternal mortality were seen. Conclusion Hypomagnesemia occurs during states of preeclampsia and eclampsia, and, administration of magnesium sulphate is effective and safe in preventing maternal mortality.

Serum magnesium levels in patients with pre-eclampsia and eclampsia with different regimens of magnesium sulphate

Directory of Open Access Journals (Sweden)

Arpita Singh

2013-03-01

Full Text Available Background Pre-eclampsia and the subsequent eclampsia account for a common cause of maternal mortality worldwide and efforts aimed at reducing its menace are vital. Objective To estimate the serum magnesium levels in pre-eclampsia and eclampsia and to study the effect of using different regimens of magnesium sulphate. Methods 70 cases of pre-eclampsia and eclampsia and 35 normal pregnant women as controls were studied. Serum magnesium levels were estimated using Atomic Absorption Spectrophotometer (Model AAS-4139 at baseline and at frequent intervals during gestation and the overall parameters were meticulously observed. Results Majority (60% of studied cases was nullipara with gestation age of 36-40 weeks. Statistically significant reduction of mean diastolic blood pressure and protein-urea was observed after using both intramuscular and intravenous regimens of magnesium sulphate. Mean initial serum magnesium level (mg/dl±SD was 1.81±0.58 in group A,1.55±0.41 in group B and 1.49±0.41 in group C. Mean serum magnesium levels during first 4 hours after therapy were statistically significant between intramuscular and intravenous regimen groups while same were statistically insignificant at 8,12,16,24 and 32 hours. Besides, few minor side effects including headache, vomiting, reduced tendon reflexes and thrombocytopenia, no severe side effects and no maternal mortality were seen. Conclusion Hypomagnesemia occurs during states of preeclampsia and eclampsia, and, administration of magnesium sulphate is effective and safe in preventing maternal mortality.

Computational micromechanics of bioabsorbable magnesium stents.

Science.gov (United States)

Grogan, J A; Leen, S B; McHugh, P E

2014-06-01

Magnesium alloys are a promising candidate material for an emerging generation of absorbable metal stents. Due to its hexagonal-close-packed lattice structure and tendency to undergo twinning, the deformation behaviour of magnesium is quite different to that of conventional stent materials, such as stainless steel 316L and cobalt chromium L605. In particular, magnesium exhibits asymmetric plastic behaviour (i.e. different yield behaviours in tension and compression) and has lower ductility than these conventional alloys. In the on-going development of absorbable metal stents it is important to assess how the unique behaviour of magnesium affects device performance. The mechanical behaviour of magnesium stent struts is investigated in this study using computational micromechanics, based on finite element analysis and crystal plasticity theory. The plastic deformation in tension and bending of textured and non-textured magnesium stent struts with different numbers of grains through the strut dimension is investigated. It is predicted that, unlike 316L and L605, the failure risk and load bearing capacity of magnesium stent struts during expansion is not strongly affected by the number of grains across the strut dimensions; however texturing, which may be introduced and controlled in the manufacturing process, is predicted to have a significant influence on these measures of strut performance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Magnesium fluoride recovery method

International Nuclear Information System (INIS)

Gay, R.L.; McKenzie, D.E.

1989-01-01

A method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag formed in the production of metallic uranium by the reduction of depleted uranium tetrafluoride with metallic magnesium in a retort wherein the slag contains the free metals magnesium and uranium and also oxides and fluorides of the metals. The slag having a radioactivity level of at least about 7,000 rhoCi/gm. The method comprises the steps of: grinding the slag to a median particle size of about 200 microns; contacting the ground slag in a reaction zone with an acid having a strength of from about 0.5 to 1.5 N for a time of from about 4 to about 20 hours in the presence of a catalytic amount of iron; removing the liquid product; treating the particulate solid product; repeating the last two steps at least one more time to produce a solid residue consisting essentially of magnesium fluoride substantially free of uranium and having a residual radioactivity level of less than about 1000 rhoCi/gm

Radioactive {sup 210}Po in magnesium supplements

Energy Technology Data Exchange (ETDEWEB)

Struminska-Parulska, Dagmara Ida [Gdansk Univ. (Poland). Environmental Chemistry and Radiochemistry Chair

2016-08-01

The aim of this pioneer study was to determine polonium {sup 210}Po in the most popular magnesium supplements in Poland and estimate the possible related dose assessment to the consumers. The analyzed magnesium pharmaceutics contained organic or inorganic magnesium compounds; some from natural sources. The objectives of this research were to investigate the naturally occurring {sup 210}Po activity concentrations in magnesium supplements, find the correlations between {sup 210}Po concentration in medicament and magnesium chemical form, and calculate the effective radiation dose connected to analyzed magnesium supplement consumption. The highest {sup 210}Po activity concentrations were determined in mineral tablets made from sedimentary rocks, namely dolomite - 3.84 ± 0.15 mBq g{sup -1} (sample Mg17). The highest annual radiation dose from {sup 210}Po taken with 1 tablet of magnesium supplement per day or with 400 mg of pure Mg daily would come from sample Mg17 (dolomite) - 1.35 ± 0.5 and 8.44 ± 0.33 μSv year{sup -1} respectively.

Distinction between magnesium diboride and tetraboride by kelvin probe force microscopy

International Nuclear Information System (INIS)

Kim, Du-Na; Caron, Arnaud; Park, Hai Woong

2016-01-01

We analyze mixtures of magnesium diboride and tetraboride synthesized with magnesium powders of different shapes. To distinguish between magnesium diboride and tetraboride we use the contrast of kelvin probe force microscopy. The microstructural morphology strongly depends on the shape of the magnesium powders used in the reaction between magnesium and magnesium tetraboride to form magnesium diboride. With spherical magnesium powder an equiaxed microstructure of magnesium diboride is formed with residual magnesium tetraboride at the grain boundaries. With plate-like magnesium powders elongated magnesium diboride grains are formed. In this case, residual magnesium tetraboride is found to agglomerate.

Mechanistic Study of Magnesium Carbonate Semibatch Reactive Crystallization with Magnesium Hydroxide and CO2

DEFF Research Database (Denmark)

Han, B.; Qu, H. Y.; Niemi, H.

2014-01-01

This work investigates semibatch precipitation of magnesium carbonate at ambient temperature and pressure using Mg(OH)(2) and CO2 as starting materials. A thermal analysis method was developed that reflects the dissolution rate of Mg(OH)(2) and the formation of magnesium carbonate. The method...... the liquid and solid phases. A stirring rate of 650 rpm was found to be the optimum speed as the flow rate of CO2 was 1 L/min. Precipitation rate increased with gas flow rate, which indicates that mass transfer of CO2 plays a critical role in this precipitation case. Magnesium carbonate trihydrate...

Solvation of magnesium dication: molecular dynamics simulation and vibrational spectroscopic study of magnesium chloride in aqueous solutions.

Science.gov (United States)

Callahan, Karen M; Casillas-Ituarte, Nadia N; Roeselová, Martina; Allen, Heather C; Tobias, Douglas J

2010-04-22

Magnesium dication plays many significant roles in biochemistry. While it is available to the environment from both ocean waters and mineral salts on land, its roles in environmental and atmospheric chemistry are still relatively unknown. Several pieces of experimental evidence suggest that contact ion pairing may not exist at ambient conditions in solutions of magnesium chloride up to saturation concentrations. This is not typical of most ions. There has been disagreement in the molecular dynamics literature concerning the existence of ion pairing in magnesium chloride solutions. Using a force field developed during this study, we show that contact ion pairing is not energetically favorable. Additionally, we present a concentration-dependent Raman spectroscopic study of the Mg-O(water) hexaaquo stretch that clearly supports the absence of ion pairing in MgCl(2) solutions, although a transition occurring in the spectrum between 0.06x and 0.09x suggests a change in solution structure. Finally, we compare experimental and calculated observables to validate our force field as well as two other commonly used magnesium force fields, and in the process show that ion pairing of magnesium clearly is not observed at higher concentrations in aqueous solutions of magnesium chloride, independent of the choice of magnesium force field, although some force fields give better agreement to experimental results than others.

Intradermal administration of magnesium sulphate and magnesium chloride produces hypesthesia to mechanical but hyperalgesia to heat stimuli in humans

Directory of Open Access Journals (Sweden)

Ikemoto Tatsunori

2009-08-01

Full Text Available Abstract Background Although magnesium ions (Mg2+ are known to display many similar features to other 2+ charged cations, they seem to have quite an important and unique role in biological settings, such as NMDA blocking effect. However, the role of Mg2+ in the neural transmission system has not been studied as sufficiently as calcium ions (Ca2+. To clarify the sensory effects of Mg2+ in peripheral nervous systems, sensory changes after intradermal injection of Mg2+ were studied in humans. Methods Magnesium sulphate, magnesium chloride and saline were injected into the skin of the anterior region of forearms in healthy volunteers and injection-induced irritating pain ("irritating pain", for short, tactile sensation, tactile pressure thresholds, pinch-pain changes and intolerable heat pain thresholds of the lesion were monitored. Results Flare formation was observed immediately after magnesium sulphate or magnesium chloride injection. We found that intradermal injections of magnesium sulphate and magnesium chloride transiently caused irritating pain, hypesthesia to noxious and innocuous mechanical stimulations, whereas secondary hyperalgesia due to mechanical stimuli was not observed. In contrast to mechanical stimuli, intolerable heat pain-evoking temperature was significantly decreased at the injection site. In addition to these results, spontaneous pain was immediately attenuated by local cooling. Conclusion Membrane-stabilizing effect and peripheral NMDA-blocking effect possibly produced magnesium-induced mechanical hypesthesia, and extracellular cation-induced sensitization of TRPV1 channels was thought to be the primary mechanism of magnesium-induced heat hyperalgesia.

Effect of magnesium hydride on the corrosion behavior of an AZ91 magnesium alloy in sodium chloride solution

International Nuclear Information System (INIS)

Chen Jian; Dong Junhua; Wang Jianqiu; Han Enhou; Ke Wei

2008-01-01

The effect of magnesium hydride on the corrosion behavior of an as-cast AZ91 alloy in 3.5 wt.% NaCl solution was investigated using gas collection method and potentiostatic test. The Pourbaix diagram of Mg-H 2 O system was built using thermodynamic calculation. It was possible that magnesium hydride could form in the whole pH range in theory. The experimental results showed that at cathodic region, magnesium hydride formed on surface, which was the controlling process for the corrosion behavior of AZ91 alloy; at anodic region and free corrosion potential, magnesium hydride model and partially protective film model, monovalent magnesium ion model and particle undermining model were responsible for the corrosion process of AZ91 alloy

Higher dietary magnesium intake and higher magnesium status are associated with lower prevalence of coronary heart disease in patients with type 2 diabetes

NARCIS (Netherlands)

Gant, C.M.; Soedamah-Muthu, S.S.; Binnenmars, S.H.; Bakker, S.J.L.; Navis, G.; Laverman, G.D.

2018-01-01

In type 2 diabetes mellitus (T2D), the handling of magnesium is disturbed. Magnesium deficiency may be associated with a higher risk of coronary heart disease (CHD). We investigated the associations between (1) dietary magnesium intake; (2) 24 h urinary magnesium excretion; and (3) plasma magnesium

Serum magnesium concentration in drug-addicted patients.

Science.gov (United States)

Karakiewicz, Beata; Kozielec, Tadeusz; Brodowski, Jacek; Chlubek, Dariusz; Noceń, Iwona; Starczewski, Andrzej; Brodowska, Agnieszka; Laszczyńska, Maria

2007-03-01

Drug addiction is a complex problem which leads to many somatic, psychic and social diseases. It is accompanied by the disturbed metabolism of various macro and micronutrients. The aim of this study was to assess serum magnesium concentration in drug-addicted patients and analyze whether Human Immunodeficiency Virus (HIV) infection and methadone treatment affect the level of serum magnesium in these patients. The examination was conducted in a group of 83 people - patients of Szczecin-Zdroje Psychiatric Hospital (Poland). They were 21 to 49 years old, and the mean age was 32 +/- 7 years. The control group consisted of 81 healthy individuals. Flame atomic-absorption spectrometry method was used to determine the magnesium concentration. The total serum magnesium concentration was calculated for the whole patient group, subgroups of women and men, a subgroup of people infected with HIV, and a subgroup receiving methadone substitution treatment. How magnesium behaves depending on age and addiction period, was checked. The mean concentration of magnesium in blood serum of the patients examined was 0.57 mmol/L, which was significantly lower than in the control group. In the subgroup of men it was 0.57 mmol/L, and in the subgroup of women - 0.55 mmol/L; the differences were not statistically significant. In the patient group nobody had the appropriate magnesium concentration in blood serum. No significant correlation was found between the magnesium concentration, age of the patients and addiction period. In the subgroup of seropositive people the mean concentration of magnesium was 0.55 mmol/L, and in the subgroup of non-infected patients - 0.58 mmol/L; the difference was not statistically significant. The mean concentration of magnesium in the subgroup treated with methadone was 0.59 mmol/L, and in the subgroup not involved in this type of therapy - 0.55 mmol/L; it was not a statistically significant difference.

The Role of Magnesium in Neurological Disorders

Directory of Open Access Journals (Sweden)

Anna E. Kirkland

2018-06-01

Full Text Available Magnesium is well known for its diverse actions within the human body. From a neurological standpoint, magnesium plays an essential role in nerve transmission and neuromuscular conduction. It also functions in a protective role against excessive excitation that can lead to neuronal cell death (excitotoxicity, and has been implicated in multiple neurological disorders. Due to these important functions within the nervous system, magnesium is a mineral of intense interest for the potential prevention and treatment of neurological disorders. Current literature is reviewed for migraine, chronic pain, epilepsy, Alzheimer’s, Parkinson’s, and stroke, as well as the commonly comorbid conditions of anxiety and depression. Previous reviews and meta-analyses are used to set the scene for magnesium research across neurological conditions, while current research is reviewed in greater detail to update the literature and demonstrate the progress (or lack thereof in the field. There is strong data to suggest a role for magnesium in migraine and depression, and emerging data to suggest a protective effect of magnesium for chronic pain, anxiety, and stroke. More research is needed on magnesium as an adjunct treatment in epilepsy, and to further clarify its role in Alzheimer’s and Parkinson’s. Overall, the mechanistic attributes of magnesium in neurological diseases connote the macromineral as a potential target for neurological disease prevention and treatment.

Nanostructured magnesium has fewer detrimental effects on osteoblast function

Directory of Open Access Journals (Sweden)

Weng L

2013-05-01

Full Text Available Lucy Weng, Thomas J Webster School of Engineering and Department of Orthopedics, Brown University, Providence, RI, USA Abstract: Efforts have been made recently to implement nanoscale surface features on magnesium, a biodegradable metal, to increase bone formation. Compared with normal magnesium, nanostructured magnesium has unique characteristics, including increased grain boundary properties, surface to volume ratio, surface roughness, and surface energy, which may influence the initial adsorption of proteins known to promote the function of osteoblasts (bone-forming cells. Previous studies have shown that one way to increase nanosurface roughness on magnesium is to soak the metal in NaOH. However, it has not been determined if degradation of magnesium is altered by creating nanoscale features on its surface to influence osteoblast density. The aim of the present in vitro study was to determine the influence of degradation of nanostructured magnesium, created by soaking in NaOH, on osteoblast density. Our results showed a less detrimental effect of magnesium degradation on osteoblast density when magnesium was treated with NaOH to create nanoscale surface features. The detrimental degradation products of magnesium are of significant concern when considering use of magnesium as an orthopedic implant material, and this study identified a surface treatment, ie, soaking in NaOH to create nanoscale features for magnesium that can improve its use in numerous orthopedic applications. Keywords: nanostructured magnesium, degradation, detrimental effects, osteoblasts

Corrosion Screening of EV31A Magnesium and Other Magnesium Alloys using Laboratory-Based Accelerated Corrosion and Electro-Chemical Methods

Science.gov (United States)

2014-07-01

Spray. Journal of Failure Analysis and Prevention 2008, 8 (2), 164–175. 34. Aluminium Alloy 5083, Plate and Sheet; SAE-AMS-QQ-A-250/6S; SAE...Corrosion Screening of EV31A Magnesium and Other Magnesium Alloys Using Laboratory-Based Accelerated Corrosion and Electro-chemical Methods...Magnesium and Other Magnesium Alloys Using Laboratory-Based Accelerated Corrosion and Electro-chemical Methods Brian E. Placzankis, Joseph P

Hydrostatic extrusion of magnesium alloys

NARCIS (Netherlands)

Sillekens, W.H.; Bohlen, J.

2012-01-01

This chapter deals with the capabilities and limitations of the hydrostatic extrusion process for the manufacturing of magnesium alloy sections. Firstly, the process basics for the hydrostatic extrusion of materials in general and of magnesium in particular are introduced. Next, some recent research

Magnesium bicarbonate as an in situ uranium lixiviant

International Nuclear Information System (INIS)

Sibert, J.W.

1984-01-01

In the subsurface solution mining of mineral values, especially uranium, in situ, magnesium bicarbonate leaching solution is used instead of sodium, potassium and ammonium carbonate and bicarbonates. The magnesium bicarbonate solution is formed by combining carbon dioxide with magnesium oxide and water. The magnesium bicarbonate lixivant has four major advantages over prior art sodium, potassium and ammonium bicarbonates

Magnesium supplement in pregnancy-induced hypertension. A clinicopathological study

DEFF Research Database (Denmark)

Rudnicki, M; Junge, Jette; Frølich, A

1990-01-01

as a double-blind randomized controlled study in which 11 women were allocated to magnesium and 7 to placebo treatment. The treatment comprised a 48-hour intravenous magnesium/placebo infusion followed by daily oral magnesium/placebo intake until one day after delivery. Magnesium supplement increased birth....... There was no significant difference when the magnesium group, the placebo group and the control group were compared separately. The present study suggests that magnesium supplement has a beneficial effect on fetal growth in pregnancy-induced hypertension. With regard to the light and electron microscopic changes we were...... unable to demonstrate any significant difference between the magnesium, placebo and control groups....

Preparation and corrosion resistance of magnesium phytic acid/hydroxyapatite composite coatings on biodegradable AZ31 magnesium alloy.

Science.gov (United States)

Zhang, Min; Cai, Shu; Zhang, Feiyang; Xu, Guohua; Wang, Fengwu; Yu, Nian; Wu, Xiaodong

2017-06-01

In this work, a magnesium phytic acid/hydroxyapatite composite coating was successfully prepared on AZ31 magnesium alloy substrate by chemical conversion deposition technology with the aim of improving its corrosion resistance and bioactivity. The influence of hydroxyapatite (HA) content on the microstructure and corrosion resistance of the coatings was investigated. The results showed that with the increase of HA content in phytic acid solution, the cracks on the surface of the coatings gradually reduced, which subsequently improved the corrosion resistance of these coated magnesium alloy. Electrochemical measurements in simulated body fluid (SBF) revealed that the composite coating with 45 wt.% HA addition exhibited superior surface integrity and significantly improved corrosion resistance compared with the single phytic acid conversion coating. The results of the immersion test in SBF showed that the composite coating could provide more effective protection for magnesium alloy substrate than that of the single phytic acid coating and showed good bioactivity. Magnesium phytic acid/hydroxyapatite composite, with the desired bioactivity, can be synthesized through chemical conversion deposition technology as protective coatings for surface modification of the biodegradable magnesium alloy implants. The design idea of the new type of biomaterial is belong to the concept of "third generation biomaterial". Corrosion behavior and bioactivity of coated magnesium alloy are the key issues during implantation. In this study, preparation and corrosion behavior of magnesium phytic acid/hydroxyapatite composite coatings on magnesium alloy were studied. The basic findings and significance of this paper are as follows: 1. A novel environmentally friendly, homogenous and crack-free magnesium phytic acid/hydroxyapatite composite coating was fabricated on AZ31 magnesium alloy via chemical conversion deposition technology with the aim of enhancing its corrosion resistance and

Nanostructured magnesium has fewer detrimental effects on osteoblast function

Science.gov (United States)

Weng, Lucy; Webster, Thomas J

2013-01-01

Efforts have been made recently to implement nanoscale surface features on magnesium, a biodegradable metal, to increase bone formation. Compared with normal magnesium, nanostructured magnesium has unique characteristics, including increased grain boundary properties, surface to volume ratio, surface roughness, and surface energy, which may influence the initial adsorption of proteins known to promote the function of osteoblasts (bone-forming cells). Previous studies have shown that one way to increase nanosurface roughness on magnesium is to soak the metal in NaOH. However, it has not been determined if degradation of magnesium is altered by creating nanoscale features on its surface to influence osteoblast density. The aim of the present in vitro study was to determine the influence of degradation of nanostructured magnesium, created by soaking in NaOH, on osteoblast density. Our results showed a less detrimental effect of magnesium degradation on osteoblast density when magnesium was treated with NaOH to create nanoscale surface features. The detrimental degradation products of magnesium are of significant concern when considering use of magnesium as an orthopedic implant material, and this study identified a surface treatment, ie, soaking in NaOH to create nanoscale features for magnesium that can improve its use in numerous orthopedic applications. PMID:23674891

Nanostructured magnesium has fewer detrimental effects on osteoblast function.

Science.gov (United States)

Weng, Lucy; Webster, Thomas J

2013-01-01

Efforts have been made recently to implement nanoscale surface features on magnesium, a biodegradable metal, to increase bone formation. Compared with normal magnesium, nanostructured magnesium has unique characteristics, including increased grain boundary properties, surface to volume ratio, surface roughness, and surface energy, which may influence the initial adsorption of proteins known to promote the function of osteoblasts (bone-forming cells). Previous studies have shown that one way to increase nanosurface roughness on magnesium is to soak the metal in NaOH. However, it has not been determined if degradation of magnesium is altered by creating nanoscale features on its surface to influence osteoblast density. The aim of the present in vitro study was to determine the influence of degradation of nanostructured magnesium, created by soaking in NaOH, on osteoblast density. Our results showed a less detrimental effect of magnesium degradation on osteoblast density when magnesium was treated with NaOH to create nanoscale surface features. The detrimental degradation products of magnesium are of significant concern when considering use of magnesium as an orthopedic implant material, and this study identified a surface treatment, ie, soaking in NaOH to create nanoscale features for magnesium that can improve its use in numerous orthopedic applications.

The role of magnesium in the electrochemical behaviour of 5XXX aluminium-magnesium alloys

NARCIS (Netherlands)

Flores Ramirez, J.R.

2006-01-01

An investigation concerning the effects of magnesium on the intergranular corrosion susceptibility of AA5XXX aluminium alloys was carried out. In the present work, magnesium is found to be highly mobile in the bulk metal as well as in the aluminium oxide. This mobility is also found to be dependent

Solubilities of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid in water

Energy Technology Data Exchange (ETDEWEB)

Mishelevich, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel); Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel)], E-mail: apelblat@bgu.ac.il

2008-05-15

The solubility in water of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid was determined in the 278.15 K to 343.15 K temperature range. The solubility of these compounds served to permit the evaluation of the apparent molar enthalpies of solution.

Solubilities of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid in water

International Nuclear Information System (INIS)

Mishelevich, Alexander; Apelblat, Alexander

2008-01-01

The solubility in water of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid was determined in the 278.15 K to 343.15 K temperature range. The solubility of these compounds served to permit the evaluation of the apparent molar enthalpies of solution

Study of Serum Magnesium in Surgical Stress

Directory of Open Access Journals (Sweden)

Sandip D. Lambe

2016-10-01

Full Text Available Background: A deficiency of magnesium is of clinical importance in hospitalized patients. The prevalence of hypomagnesaemia is high in critically ill patients. Knowing the important role of magnesium in surgical cases, it is necessary to anticipate and diagnose magnesium deficiency prior to surgery and in the immediate postoperative period to correct it. Aims and Objectives: The aim of this study was to analyse serum magnesium levels in patients undergoing emergency surgical procedures, planned surgical procedures and normal healthy matched controls and to compare the serum magnesium levels in all the three groups. Materials and Methods: The study participants were divided into three groups: i Group I: patients undergoing emergency major surgery ii Group II: patients undergoing planned major surgery iii Group III: normal healthy controls. Serum Magnesium investigation was done by Xylidyl Blue Method using UV-1800/Shimadzu UV-Spectrophotometer. Results: The mean serum Magnesium in control group was found to be 2.16 ± 0.30 mg/dl. In patients undergoing planned surgery, pre-operative serum magnesium was normal (2.16 ± 0.22 mg/dl but decreased significantly on postoperative day 3 (1.63 ± 0.27 mg/dl and day 6 (1.97 ± 0.12 mg/dl and returned to normal level by post-operative day 9 (2.14 ± 0.14 mg/dl compared to controls. In patients undergoing emergency surgery, serum magnesium was decreased pre-operatively (1.90 ± 0.48 mg/dl.Further significant reduction was found at post-operative day 3 (1.38 ± 0.28 mg/dl, day 6 (1.59 ± 0.30 mg/dl and day 9 (1.88 ± 0.46 mg/dl compared to controls. Mean serum Magnesium overall in emergency surgery patients was reduced significantly compared to planned surgery patients. Conclusion: A transient fall in the serum Magnesium as compared to its pre-operative level was seen in every patient undergoing surgical procedure due to surgical stress. In patients undergoing emergency surgical procedure, the decrease was

Low Temperature Synthesis of Magnesium Aluminate Spinel

International Nuclear Information System (INIS)

Lebedovskaya, E.G.; Gabelkov, S.V.; Litvinenko, L.M.; Logvinkov, D.S.; Mironova, A.G.; Odejchuk, M.A.; Poltavtsev, N.S.; Tarasov, R.V.

2006-01-01

The low-temperature synthesis of magnesium-aluminum spinel is carried out by a method of thermal decomposition in combined precipitated hydrates. The fine material of magnesium-aluminium spinel with average size of coherent dispersion's area 4...5 nanometers is obtained. Magnesium-aluminum spinel and initial hydrates were investigated by methods of the differential thermal analysis, the x-ray phase analysis and measurements of weight loss during the dehydration and thermal decomposition. It is established that synthesis of magnesium-aluminum spinel occurs at temperature 300 degree C by method of the x-ray phase analysis

Wide Strip Casting Technology of Magnesium Alloys

Science.gov (United States)

Park, W.-J.; Kim, J. J.; Kim, I. J.; Choo, D.

Extensive investigations relating to the production of high performance and low cost magnesium sheet by strip casting have been performed for the application to automotive parts and electronic devices. Research on magnesium sheet production technology started in 2004 by Research Institute of Industrial Science and Technology (RIST) with support of Pohang Iron and Steel Company (POSCO). POSCO has completed the world's first plant to manufacture magnesium coil. Another big project in order to develop wide strip casting technology for the automotive applications of magnesium sheets was started in succession.

Effect of oxygen on the hydrogenation properties of magnesium films

DEFF Research Database (Denmark)

Ostenfeld, Christopher Worsøe; Chorkendorff, Ib

2006-01-01

The effect of magnesium oxide on the magnesium and hydrogen desorption properties of magnesium films have been investigated. We find that by capping metallic magnesium films with oxide overlayers the apparent desorption energy of magnesium is increased from 146 kJ/mol to 314 kJ/mol. The results...... are discussed in light of previous investigations of ball-milled magnesium powders....

Composites having an intermetallic containing matrix

International Nuclear Information System (INIS)

Nagle, D.C.; Brupbacher, J.M.; Christodoulou, L.

1990-01-01

This paper describes a composite material. It comprises: a dispersion of in-situ precipitated second phase particles selected from the group consisting of borides, carbides, nitrides, and sulfides, in an intermetallic containing matrix selected from the group consisting of the aluminides, silicides, and beryllides of nickel, copper, titanium, cobalt, iron, platinum, gold, silver, niobium, tantalum, zinc, molybdenum, hafnium, tin, tungsten, lithium, magnesium, thorium, chromium, vanadium, zirconium, and manganese

The potential for ionic liquid electrolytes to stabilise the magnesium interface for magnesium/air batteries

International Nuclear Information System (INIS)

Khoo, Timothy; Howlett, Patrick C.; Tsagouria, Maureen; MacFarlane, Douglas R.; Forsyth, Maria

2011-01-01

Magnesium/air batteries are a possible high-energy density power source that, to date, have not received strong commercial interest due to issues with the corrosion of the magnesium and evaporation of the electrolyte. In this work we report on the use of ionic liquid based electrolytes to stabilise the metal/electrolyte interface and their impact on the electrochemical performance. Galvanostatic measurements indicate that the water content of the ionic liquid electrolyte plays an important role in the cell discharge characteristics. Surface characterisation using EIS, ATR-FTIR and powder diffraction examined the unique properties of the surface film formed on the magnesium anode.

Irradiation effects in magnesium and aluminium alloys

International Nuclear Information System (INIS)

Sturcken, E.F.

1979-01-01

Effects of neutron irradiation on microstructure, mechanical properties and swelling of several magnesium and aluminium alloys were studied. The neutron fluences of 2-3 X 10 22 n/cm 2 , >0.2 MeV produced displacement doses of 20 to 45 displacements per atom (dpa). Ductility of the magnesium alloys was severely reduced by irradiation induced recrystallization and precipitation of various forms. Precipitation of transmuted silicon occurred in the aluminium alloys. However, the effect on ductility was much less than for the magnesium alloys. The magnesium and aluminium alloys had excellent resistance to swelling: The best magnesium alloy was Mg/3.0 wt% Al/0.19 wt% Ca; its density decreased by only 0.13%. The best aluminium alloy was 6063, with a density decrease of 0.22%. (Auth.)

Electrolytes for magnesium electrochemical cells

Science.gov (United States)

Burrell, Anthony K.; Sa, Niya; Proffit, Danielle Lee; Lipson, Albert; Liao, Chen; Vaughey, John T.; Ingram, Brian J.

2017-07-04

An electrochemical cell includes a high voltage cathode configured to operate at 1.5 volts or greater; an anode including Mg.sup.0; and an electrolyte including an ether solvent and a magnesium salt; wherein: a concentration of the magnesium salt in the ether is 1 M or greater.

EFFECT OF MAGNESIUM SULFATE (A LAXATIVE) ON ...

African Journals Online (AJOL)

use with little success . Magnesium sulfate also known as Epsom salt or bitter salt is a hydrate salt with a chemical name of magnesium sulfate heptahydrate . Chemical formula is MgSO. 7HO and trade name is. Andrews liver salt. Dried magnesium sulfate is an osmotic laxative or a saline laxative that acts by increasing the.

Immunological Response to Biodegradable Magnesium Implants

Science.gov (United States)

Pichler, Karin; Fischerauer, Stefan; Ferlic, Peter; Martinelli, Elisabeth; Brezinsek, Hans-Peter; Uggowitzer, Peter J.; Löffler, Jörg F.; Weinberg, Annelie-Martina

2014-04-01

The use of biodegradable magnesium implants in pediatric trauma surgery would render surgical interventions for implant removal after tissue healing unnecessary, thereby preventing stress to the children and reducing therapy costs. In this study, we report on the immunological response to biodegradable magnesium implants—as an important aspect in evaluating biocompatibility—tested in a growing rat model. The focus of this study was to investigate the response of the innate immune system to either fast or slow degrading magnesium pins, which were implanted into the femoral bones of 5-week-old rats. The main alloying element of the fast-degrading alloy (ZX50) was Zn, while it was Y in the slow-degrading implant (WZ21). Our results demonstrate that degrading magnesium implants beneficially influence the immune system, especially in the first postoperative weeks but also during tissue healing and early bone remodeling. However, rodents with WZ21 pins showed a slightly decreased phagocytic ability during bone remodeling when the degradation rate reached its maximum. This may be due to the high release rate of the rare earth-element yttrium, which is potentially toxic. From our results we conclude that magnesium implants have a beneficial effect on the innate immune system but that there are some concerns regarding the use of yttrium-alloyed magnesium implants, especially in pediatric patients.

Magnesium substitution in the structure of orthopedic nanoparticles: A comparison between amorphous magnesium phosphates, calcium magnesium phosphates, and hydroxyapatites

International Nuclear Information System (INIS)

Nabiyouni, Maryam; Ren, Yufu; Bhaduri, Sarit B.

2015-01-01

As biocompatible materials, magnesium phosphates have received a lot of attention for orthopedic applications. During the last decade multiple studies have shown advantages for magnesium phosphate such as lack of cytotoxicity, biocompatibility, strong mechanical properties, and high biodegradability. The present study investigates the role of Mg +2 and Ca +2 ions in the structure of magnesium phosphate and calcium phosphate nanoparticles. To directly compare the effect of Mg +2 and Ca +2 ions on structure of nanoparticles and their biological behavior, three groups of nanoparticles including amorphous magnesium phosphates (AMPs) which release Mg +2 , calcium magnesium phosphates (CMPs) which release Mg +2 and Ca +2 , and hydroxyapatites (HAs) which release Ca +2 were studied. SEM, TEM, XRD, and FTIR were used to evaluate the morphology, crystallinity, and chemical properties of the particles. AMP particles were homogeneous nanospheres, whereas CMPs were combinations of heterogeneous nanorods and nanospheres, and HAs which contained heterogeneous nanosphere particles. Cell compatibility was monitored in all groups to determine the cytotoxicity effect of particles on studied MC3T3-E1 preosteoblasts. AMPs showed significantly higher attachment rate than the HAs after 1 day and both AMPs and CMPs showed significantly higher proliferation rate when compared to HAs after 7 days. Gene expression level of osteoblastic markers ALP, COL I, OCN, OPN, RUNX2 were monitored and they were normalized to GAPDH housekeeping gene. Beta actin expression level was monitored as the second housekeeping gene to confirm the accuracy of results. In general, AMPs and CMPs showed higher expression level of osteoblastic genes after 7 days which can further confirm the stimulating role of Mg + 2 and Ca +2 ions in increasing the proliferation rate, differentiation, and mineralization of MC3T3-E1 preosteoblasts. - Highlights: • Role of Mg 2+ and Ca 2+ ions in proliferation, and differentiation

Investigation of magnesium oxychloride cement at the initial hardening stage

Directory of Open Access Journals (Sweden)

Averina Galina

2018-01-01

Full Text Available The paper investigates the process of variation of magnesium oxychloride cement deformations at the initial hardening stage depending on the activity of magnesium oxide powder which is determined by the parameters of the source material burning. Investigation is focused on magnesium cements obtained from pure magnesium hydroxide. Source materials were burnt at various temperatures with the purpose to obtain magnesium oxide powder with different activity. Regular content of hydrated phases was determined in hardened magnesium cement prepared on the basis of binders with different activity. The study reveals the influence of magnesium oxide powder activity on the process of deformation occurrence in hardened magnesium cement and its tendency to crack formation.

Recrystallization of magnesium deformed at low temperatures

International Nuclear Information System (INIS)

Fromageau, R.; Pastol, J.L.; Revel, G.

1978-01-01

The recrystallization of magnesium was studied after rolling at temperatures ranging between 248 and 373 K. For zone refined magnesium the annealing behaviour as observed by electrical resistivity measurements showed two stages at about 250 K and 400 K due respectively to recrystallization and grain growth. The activation energy associated with the recrystallization stage was 0.75 +- 0.01 eV. In less pure magnesium, with nominal purity 99.99 and 99.9%, the recrystallization stage was decomposed into two substages. Activation energies were determined in relation with deformation temperature and purity. The magnesium of intermediate purity (99.99%) behaved similarly to the lowest purity metal when it was deformed at high temperature and to the purest magnesium when the deformation was made at low temperature. This behaviour was discussed in connection with the theories of Luecke and Cahn. (Auth.)

Benefits of magnesium wheels for consumer cars

Science.gov (United States)

Frishfelds, Vilnis; Timuhins, Andrejs; Bethers, Uldis

2018-05-01

Advantages and disadvantages of magnesium wheels are considered based on a mechanical model of a car. Magnesium wheels are usually applied to racing cars as they provide slightly better strength/weight ratio than aluminum alloys. Do they provide notable benefits also for the everyday user when the car speeds do not exceed allowed speed limit? Distinct properties of magnesium rims are discussed. Apart from lighter weight of magnesium alloys, they are also good in dissipating the energy of vibrations. The role of energy dissipation in the rim of a wheel is estimated by a quarter car model. Improvements to safety by using the magnesium wheels are considered. Braking distance and responsiveness of the car is studied both with and without using an Anti Blocking System (ABS). Influence of rim weight on various handling parameters of the car is quantitatively tested.

A review on hot tearing of magnesium alloys

Directory of Open Access Journals (Sweden)

Jiangfeng Song

2016-09-01

Full Text Available Hot tearing is often a major casting defect in magnesium alloys and has a significant impact on the quality of their casting products. Hot tearing of magnesium alloys is a complex solidification phenomenon which is still not fully understood, it is of great importance to investigate the hot tearing behaviour of magnesium alloys. This review attempts to summarize the investigations on hot tearing of magnesium alloys over the past decades. The hot tearing criteria including recently developed Kou's criterion are summarized and compared. The numeric simulation and assessing methods of hot tearing, factors influencing hot tearing, and hot tearing susceptibility (HTS of magnesium alloys are discussed.

Manufacturing and characterization of magnesium alloy foils for use as anode materials in rechargeable magnesium ion batteries

Science.gov (United States)

Schloffer, Daniel; Bozorgi, Salar; Sherstnev, Pavel; Lenardt, Christian; Gollas, Bernhard

2017-11-01

The fabrication of thin foils of magnesium for use as anode material in rechargeable magnesium ion batteries is described. In order to improve its workability, the magnesium was alloyed by melting metallurgy with zinc and/or gadolinium, producing saturated solid solutions. The material was extruded to thin foils and rolled to a thickness of approximately 100 μm. The electrochemical behavior of Mg-1.63 wt% Zn, Mg-1.55 wt% Gd and Mg-1.02 wt% Zn-1.01 wt% Gd was studied in (PhMgCl)2-AlCl3/THF electrolyte by cyclic voltammetry and galvanostatic cycling in symmetrical cells. Analysis of the current-potential curves in the Tafel region and the linear region close to the equilibrium potential show almost no effect of the alloying elements on the exchange current densities (5-45 μA/cm2) and the transfer coefficients. Chemical analyses of the alloy surfaces and the electrolyte demonstrate that the alloying elements not only dissolve with the magnesium during the anodic half-cycles, but also re-deposit during the cathodic half-cycles together with the magnesium and aluminum from the electrolyte. Given the negligible corrosion rate in aprotic electrolytes under such conditions, no adverse effects of alloying elements are expected for the performance of magnesium anodes in secondary batteries.

Transport of Magnesium by a Bacterial Nramp-Related Gene

Science.gov (United States)

Rodionov, Dmitry A.; Freedman, Benjamin G.; Senger, Ryan S.; Winkler, Wade C.

2014-01-01

Magnesium is an essential divalent metal that serves many cellular functions. While most divalent cations are maintained at relatively low intracellular concentrations, magnesium is maintained at a higher level (∼0.5–2.0 mM). Three families of transport proteins were previously identified for magnesium import: CorA, MgtE, and MgtA/MgtB P-type ATPases. In the current study, we find that expression of a bacterial protein unrelated to these transporters can fully restore growth to a bacterial mutant that lacks known magnesium transporters, suggesting it is a new importer for magnesium. We demonstrate that this transport activity is likely to be specific rather than resulting from substrate promiscuity because the proteins are incapable of manganese import. This magnesium transport protein is distantly related to the Nramp family of proteins, which have been shown to transport divalent cations but have never been shown to recognize magnesium. We also find gene expression of the new magnesium transporter to be controlled by a magnesium-sensing riboswitch. Importantly, we find additional examples of riboswitch-regulated homologues, suggesting that they are a frequent occurrence in bacteria. Therefore, our aggregate data discover a new and perhaps broadly important path for magnesium import and highlight how identification of riboswitch RNAs can help shed light on new, and sometimes unexpected, functions of their downstream genes. PMID:24968120

Fracture healing using degradable magnesium fixation plates and screws.

Science.gov (United States)

Chaya, Amy; Yoshizawa, Sayuri; Verdelis, Kostas; Noorani, Sabrina; Costello, Bernard J; Sfeir, Charles

2015-02-01

Internal bone fixation devices made with permanent metals are associated with numerous long-term complications and may require removal. We hypothesized that fixation devices made with degradable magnesium alloys could provide an ideal combination of strength and degradation, facilitating fracture fixation and healing while eliminating the need for implant removal surgery. Fixation plates and screws were machined from 99.9% pure magnesium and compared with titanium devices in a rabbit ulnar fracture model. Magnesium device degradation and the effect on fracture healing and bone formation were assessed after 4 weeks. Fracture healing with magnesium device fixation was compared with that of titanium devices using qualitative histologic analysis and quantitative histomorphometry. Micro-computed tomography showed device degradation after 4 weeks in vivo. In addition, 2-dimensional micro-computed tomography slices and histologic staining showed that magnesium degradation did not inhibit fracture healing or bone formation. Histomorphology showed no difference in bone-bridging fractures fixed with magnesium and titanium devices. Interestingly, abundant new bone was formed around magnesium devices, suggesting a connection between magnesium degradation and bone formation. Our results show potential for magnesium fixation devices in a loaded fracture environment. Furthermore, these results suggest that magnesium fixation devices may enhance fracture healing by encouraging localized new bone formation. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Synthesis, characterization and investigation of thermoelectric properties of selected metal borides; Synthese, Charakterisierung und Untersuchung thermoelektrischer Eigenschaften ausgewaehlter Metallboride

Energy Technology Data Exchange (ETDEWEB)

Stober, Frederick

2012-06-04

The present work deals with the high-temperature thermoelectric properties of transition metal [eg V, Cr, Mn, Ni, Cu] and lanthanide [e.g. Sc, Y, Gd, Er, Dy]-borides. In particular, intercalation compounds of beta-rhombohedral boron, compounds of the type MB{sub 66}, dodecaborides and hexaborides were examined. In the case of intercalation compounds of beta-rhombohedral boron it was found that the incorporation of metals such as Sc, Mn or Cu result in favorable thermoelectric properties. The reason is most likely the preferred occupation of the metal position M2 instead of M4. Composites, for example, DyB{sub 66}-DyB{sub 12} show high electrical conductivities, high Seebeck effects at high temperatures due to the presence of DyB{sub 12} and low thermal conductivities as a result of the DyB{sub 66} matrix. At 1100K the composite DyB{sub 66}-DyB{sub 12} shows a ZT value of 0.55, thus exceeding the ZT of boron carbide (B{sub 13}C{sub 2}) at this temperature which is considered the best p-type boride material. A composite of ErB{sub 12}-ErB{sub 4}-ErB{sub 2} has negative Seebeck coefficients and shows a ZT value of 0.5 at 840K. Furthermore, the structure of tetragonal Scandiumdodecaboride ScB{sub 12} was solved on the basis of synchrotron data from a crystalline powder, after it has been debated for decades but never fully resolved.

Behaviour of magnesium and two magnesium alloys heated in a carbon dioxide flow

International Nuclear Information System (INIS)

Boussion, M.-L.; Darras, R.; Leclercq, D.

1959-01-01

Magnesium is a particularly attractive material for sheathing uranium fuel elements in nuclear reactors in order to avoid uranium hot temperature oxidation by the cooling fluid. As this cooling fluid will be carbon dioxide at the (future) Marcoule plants, a thorough study of magnesium and magnesium alloys behaviour when heated by carbon dioxide at a 400 C temperature, have been completed. Tests on three materials (Mg, Mg-Zr and Mg-Zr-Zn) have been performed with CO 2 up to a temperature of 550 C, at atmospheric pressure in the presence of a certain amount of oxygen and nitrogen (in order to study the influence of these impurities), and at a pressure of 15 kg / cm 2 . Oxidation results are detailed. Reprint of a paper published in 'Revue de Metallurgie', LVI, n. 1, 1959, p. 61-67

Magnesium and related low alloys

Energy Technology Data Exchange (ETDEWEB)

Bernard, J; Caillat, R; Darras, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

In the first part the authors examine the comparative corrosion of commercial magnesium, of a magnesium-zirconium alloy (0,4 per cent {<=} Zr {<=} 0,7 per cent) of a ternary magnesium-zinc-zirconium alloy (0,8 per cent {<=} Zn {<=} 1,2 per cent) and of english 'Magnox type' alloys, in dry carbon dioxide-free air, in damp carbon dioxide-free air, and in dry and damp carbon dioxide, at temperatures from 300 to 600 deg. C. In the second part the structural stability of these materials is studied after annealings, of 10 to 1000 hours at 300 to 450 deg. C. Variations in grain after these heat treatments and mechanical stretching properties at room temperature are presented. Finally various creep rate and life time diagrams are given for these materials, for temperatures ranging from 300 to 450 deg. C. (author) [French] Dans une premiere partie les auteurs etudient la corrosion comparee du magnesium commercial, d'un alliage magnesium-zirconium (0,4 pour cent {<=} Zr {<=} 0,7 pour cent), d'un alliage ternaire magnesium-zinc-zirconium (0,8 pour cent {<=} Zn {<=} 1,2 pour cent), et d'alliages anglais 'type Magnox', dans l'air sec decarbonate, l'air humide decarbonate, le gaz carbonique sec et humide a des temperatures de 300 a 600 deg. C. Dans une seconde partie, est etudiee la stabilite structurale de ces materiaux apres des recuits de 300 a 450 deg. C, et de 10 a 1000 heures. Sont presentees les variations, apres ces traitements thermiques, de la grosseur du grain, et des caracteristiques mecaniques de traction a la temperature ambiante. Enfin, quelques diagrammes de vitesse de fluage et de durees de vie sont presentes sur ces materiaux pour des temperatures variant entre 300 et 450 deg. C. (auteur)

Multi-functional magnesium alloys containing interstitial oxygen atoms.

Science.gov (United States)

Kang, H; Choi, H J; Kang, S W; Shin, S E; Choi, G S; Bae, D H

2016-03-15

A new class of magnesium alloys has been developed by dissolving large amounts of oxygen atoms into a magnesium lattice (Mg-O alloys). The oxygen atoms are supplied by decomposing titanium dioxide nanoparticles in a magnesium melt at 720 °C; the titanium is then completely separated out from the magnesium melt after solidification. The dissolved oxygen atoms are located at the octahedral sites of magnesium, which expand the magnesium lattice. These alloys possess ionic and metallic bonding characteristics, providing outstanding mechanical and functional properties. A Mg-O-Al casting alloy made in this fashion shows superior mechanical performance, chemical resistance to corrosion, and thermal conductivity. Furthermore, a similar Mg-O-Zn wrought alloy shows high elongation to failure (>50%) at room temperature, because the alloy plastically deforms with only multiple slips in the sub-micrometer grains (alloys are expected to open a new paradigm in commercial alloy design.

Dose-response relationship between dietary magnesium intake, serum magnesium concentration and risk of hypertension: a systematic review and meta-analysis of prospective cohort studies.

Science.gov (United States)

Han, Hedong; Fang, Xin; Wei, Xin; Liu, Yuzhou; Jin, Zhicao; Chen, Qi; Fan, Zhongjie; Aaseth, Jan; Hiyoshi, Ayako; He, Jia; Cao, Yang

2017-05-05

The findings of prospective cohort studies are inconsistent regarding the association between dietary magnesium intake and serum magnesium concentration and the risk of hypertension. We aimed to review the evidence from prospective cohort studies and perform a dose-response meta-analysis to investigate the relationship between dietary magnesium intake and serum magnesium concentrations and the risk of hypertension. We searched systematically PubMed, EMBASE and the Cochrane Library databases from October 1951 through June 2016. Prospective cohort studies reporting effect estimates with 95% confidence intervals (CIs) for hypertension in more than two categories of dietary magnesium intake and/or serum magnesium concentrations were included. Random-effects models were used to combine the estimated effects. Nine articles (six on dietary magnesium intake, two on serum magnesium concentration and one on both) of ten cohort studies, including 20,119 cases of hypertension and 180,566 participates, were eligible for inclusion in the meta-analysis. We found an inverse association between dietary magnesium intake and the risk of hypertension [relative risk (RR) = 0.92; 95% CI: 0.86, 0.98] comparing the highest intake group with the lowest. A 100 mg/day increment in magnesium intake was associated with a 5% reduction in the risk of hypertension (RR = 0.95; 95% CI: 0.90, 1.00). The association of serum magnesium concentration with the risk of hypertension was marginally significant (RR = 0.91; 95% CI: 0.80, 1.02). Current evidence supports the inverse dose-response relationship between dietary magnesium intake and the risk of hypertension. However, the evidence about the relationship between serum magnesium concentration and hypertension is limited.

Magnesium isotope fractionation in cation-exchange chromatography

International Nuclear Information System (INIS)

Oi, T.; Yanase, S.; Kakihana, H.

1987-01-01

Band displacement chromatography of magnesium has been carried out successfully for the purpose of magnesium isotope separation by using a strongly acidic cation-exchange resin and the strontium ion as the replacement ion. A small but definite accumulation of the heavier isotopes ( 25 Mg, 26 Mg) has been observed at the front parts of the magnesium chromatograms. The heavier isotopes have been fractionated preferentially into the solution phase. The single-stage separation factors have been calculated for the 25 Mg/ 24 Mg and 26 Mg/ 24 isotopic pairs at 25 0 C. The reduced partition function ratios of magnesium species involved in the present study have been estimated

Exoelectron emission from magnesium borate glass ceramics

International Nuclear Information System (INIS)

Kawamoto, Takamichi; Yanagisawa, Hideo; Nakamichi, Hiroshi; Kikuchi, Riichi; Kawanishi, Masaharu.

1986-01-01

Thermally stimulated exoelectron emission (TSEE) of a magnesium borate glass ceramics was investigated for its application to dosemetric use. It has been found that the TSEE glow patterns of the magnesium borate glass ceramics as well as a Li 2 B 4 O 7 glass ceramics depend on the kind of the radiation used and that the heat resistance of the magnesium borate glass ceramics is higher than that of the Li 2 B 4 O 7 glass ceramics. Therefore, the TSEE glow patterns of the magnesium borate glass ceramics indicate a possibility to be used as the dose measurement for each kind of radiation in the mixed radiation field. (author)

Magnesium doping of boron nitride nanotubes

Science.gov (United States)

Legg, Robert; Jordan, Kevin

2015-06-16

A method to fabricate boron nitride nanotubes incorporating magnesium diboride in their structure. In a first embodiment, magnesium wire is introduced into a reaction feed bundle during a BNNT fabrication process. In a second embodiment, magnesium in powder form is mixed into a nitrogen gas flow during the BNNT fabrication process. MgB.sub.2 yarn may be used for superconducting applications and, in that capacity, has considerably less susceptibility to stress and has considerably better thermal conductivity than these conventional materials when compared to both conventional low and high temperature superconducting materials.

Special metallurgy - the electrical butt-welding by flashing of sintered magnesium-magnesium oxide composites (1963)

International Nuclear Information System (INIS)

Charleux, J.

1963-01-01

Electrical resistance welding has become quite important since World War II because of the need of a high yield in aeronautical production. Progress has been due in particular to the improvements made in electronically controlled apparatus making possible the automatic control of welding. For the butt-welding of sections requiring either a high production rate or a high quality weld, the flash butt-welding system has been very much developed these last few years. The use of this welding method is of great importance in the field of the bonding of oxidisable metals such as magnesium or aluminium and its alloys, because the welded joint is free from oxides. This study consists of general considerations on the flash-welding process with regard to temperature distribution in the parts during welding, and to electrical phenomena connected with flashing. Besides this general or theoretical section, we have applied the welding process to the bonding of sintered magnesium, a magnesium-magnesium oxide composite, whose use as a structural element in nuclear reactors is considered. (author) [fr

Magnesium supplement in pregnancy-induced hypertension: effects on maternal and neonatal magnesium and calcium homeostasis

DEFF Research Database (Denmark)

Rudnicki, M; Frølich, A; Fischer-Rasmussen, W

1991-01-01

The objective of this study was to evaluate the effect of low dose magnesium supplement upon maternal and fetal serum levels of mineral status in pregnancies complicated with hypertension (PIH). Twenty-five patients with PIH agreed to participate and were randomly allocated, in a double-blind man......The objective of this study was to evaluate the effect of low dose magnesium supplement upon maternal and fetal serum levels of mineral status in pregnancies complicated with hypertension (PIH). Twenty-five patients with PIH agreed to participate and were randomly allocated, in a double...... period despite a significant increased loss of calcium during the first 24 h of inclusion. Low dose maternal magnesium treatment did not cause neonatal hypocalcemia....

Band structure of superconducting MgB sub 2 and simulation of triple systems on its base

CERN Document Server

Medvedeva, N I; Zubkov, V G; Medvedeva, Y E; Freeman, A J

2001-01-01

The zone structure of the new superconductor - magnesium boride is studied through the FP-LMTO self-consistent method. The peculiarities of the MgB sub 2 electron properties are determined by the metal-like 2p-states of the boron atoms in the plane nets, forming the states density distribution near the Fermi level. The analysis of changes in the MgB sub 2 zone structure by: doping the boron sublattice (through the Be, C, N, O replacement admixtures), the magnesium sublattice (through the Be, Ca, Li, Na replacement admixtures) and availability of structural vacancies (nonstoichiometry by boron) is carried out. The MgB sub 2 electron and CaB sub 2 hypothetic structure is studied, depending on pressure

Magnesium sulphate for fetal neuroprotection

DEFF Research Database (Denmark)

Bickford, Celeste D; Magee, Laura A; Mitton, Craig

2013-01-01

of cerebral palsy (CP) averted and quality-adjusted life years (QALYs). RESULTS: From a health system and a societal perspective, respectively, a savings of $2,242 and $112,602 is obtained for each QALY gained and a savings of $30,942 and $1,554,198 is obtained for each case of CP averted when magnesium......BACKGROUND: The aim of this study was to assess the cost-effectiveness of administering magnesium sulphate to patients in whom preterm birth at ... sensitivity analyses were used to compare the administration of magnesium sulphate with the alternative of no treatment. Two separate cost perspectives were utilized in this series of analyses: a health system and a societal perspective. In addition, two separate measures of effectiveness were utilized: cases...

Improved biological performance of magnesium by micro-arc oxidation

Directory of Open Access Journals (Sweden)

W.H. Ma

2015-03-01

Full Text Available Magnesium and its alloys have recently been used in the development of lightweight, biodegradable implant materials. However, the corrosion properties of magnesium limit its clinical application. The purpose of this study was to comprehensively evaluate the degradation behavior and biomechanical properties of magnesium materials treated with micro-arc oxidation (MAO, which is a new promising surface treatment for developing corrosion resistance in magnesium, and to provide a theoretical basis for its further optimization and clinical application. The degradation behavior of MAO-treated magnesium was studied systematically by immersion and electrochemical tests, and its biomechanical performance when exposed to simulated body fluids was evaluated by tensile tests. In addition, the cell toxicity of MAO-treated magnesium samples during the corrosion process was evaluated, and its biocompatibility was investigated under in vivo conditions. The results of this study showed that the oxide coating layers could elevate the corrosion potential of magnesium and reduce its degradation rate. In addition, the MAO-coated sample showed no cytotoxicity and more new bone was formed around it during in vivo degradation. MAO treatment could effectively enhance the corrosion resistance of the magnesium specimen and help to keep its original mechanical properties. The MAO-coated magnesium material had good cytocompatibility and biocompatibility. This technique has an advantage for developing novel implant materials and may potentially be used for future clinical applications.

The Effects of High Level Magnesium Dialysis/Substitution Fluid on Magnesium Homeostasis under Regional Citrate Anticoagulation in Critically Ill.

Directory of Open Access Journals (Sweden)

Mychajlo Zakharchenko

Full Text Available The requirements for magnesium (Mg supplementation increase under regional citrate anticoagulation (RCA because citrate acts by chelation of bivalent cations within the blood circuit. The level of magnesium in commercially available fluids for continuous renal replacement therapy (CRRT may not be sufficient to prevent hypomagnesemia.Patients (n = 45 on CRRT (2,000 ml/h, blood flow (Qb 100 ml/min with RCA modality (4% trisodium citrate using calcium free fluid with 0.75 mmol/l of Mg with additional magnesium substitution were observed after switch to the calcium-free fluid with magnesium concentration of 1.50 mmol/l (n = 42 and no extra magnesium replenishment. All patients had renal indications for CRRT, were treated with the same devices, filters and the same postfilter ionized calcium endpoint (<0.4 mmol/l of prefilter citrate dosage. Under the high level Mg fluid the Qb, dosages of citrate and CRRT were consequently escalated in 9h steps to test various settings.Median balance of Mg was -0.91 (-1.18 to -0.53 mmol/h with Mg 0.75 mmol/l and 0.2 (0.06-0.35 mmol/h when fluid with Mg 1.50 mmol/l was used. It was close to zero (0.02 (-0.12-0.18 mmol/h with higher blood flow and dosage of citrate, increased again to 0.15 (-0.11-0.25 mmol/h with 3,000 ml/h of high magnesium containing fluid (p<0.001. The arterial levels of Mg were mildly increased after the change for high level magnesium containing fluid (p<0.01.Compared to ordinary dialysis fluid the mildly hypermagnesemic fluid provided even balances and adequate levels within ordinary configurations of CRRT with RCA and without a need for extra magnesium replenishment.ClinicalTrials.gov Identifier: NCT01361581.

Urinary and plasma magnesium and risk of ischemic heart disease

NARCIS (Netherlands)

Joosten, Michel M.; Gansevoort, Ron T.; Mukamal, Kenneth J.; van der Harst, Pim; Geleijnse, Johanna M.; Feskens, Edith J. M.; Navis, Gerjan; Bakker, Stephan J. L.

Background: Previous studies on dietary magnesium and risk of ischemic heart disease (IHD) have yielded inconsistent results, in part because of a lack of direct measures of actual magnesium uptake. Urinary excretion of magnesium, an indicator of dietary magnesium uptake, might provide more

A review on magnesium alloys as biodegradable materials

Science.gov (United States)

Gu, Xue-Nan; Zheng, Yu-Feng

2010-06-01

Magnesium alloys attracted great attention as a new kind of degradable biomaterials. One research direction of biomedical magnesium alloys is based on the industrial magnesium alloys system, and another is the self-designed biomedical magnesium alloys from the viewpoint of biomaterials. The mechanical, biocorrosion properties and biocompatibilities of currently reported Mg alloys were summarized in the present paper, with the mechanical properties of bone tissue, the healing period postsurgery, the pathophysiology and toxicology of the alloying elements being discussed. The strategy in the future development of biomedical Mg alloys was proposed.

Synthesis of Nano-Light Magnesium Hydride for Hydrogen Storage ...

African Journals Online (AJOL)

Abstract. Nano-light magnesium hydride that has the capability for hydrogen storage was synthesized from treatment of magnesium ribbon with hydrogen peroxide. The optimum time for complete hydrogenation of the magnesium hydride was 5 hours.

Hydrogenations of alloys and intermetallic compounds of magnesium

International Nuclear Information System (INIS)

Gavra, Z.

1981-08-01

A kinetic and thermodynamic study of the hydrogenation of alloys and intermetallic compounds of magnesium is presented. It was established that the addition of elements of the IIIA group (Al, Ga, In) to magnesium catalyses its hydrogenation. This is explained by the mechanism of diffusion of magnesium cation vacancies. The hydride Mg 2 NiH 4 was characterized by thermal analysis, x-ray diffraction and NMR measurements. The possibility of forming pseudo-binary compounds of Mg 2 Ni by the substitution of nickel or magnesium was examined. The hydrogenation of the inter-metallic compounds of the Mg-Al system was investigated. It was found that the addition of indium and nickel affected the hydrogenation kinetics. A preliminary study of the hydrogenation of various binary and ternary alloys of magnesium was carried out. (Author)

Reprint of: Improved cytotoxicity testing of magnesium materials

International Nuclear Information System (INIS)

Fischer, Janine; Pröfrock, Daniel; Hort, Norbert; Willumeit, Regine; Feyerabend, Frank

2011-01-01

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.

Reprint of: Improved cytotoxicity testing of magnesium materials

Energy Technology Data Exchange (ETDEWEB)

Fischer, Janine [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Department for Structural Research on Macromolecules, Max-Planck Str. 1, D - 21502 Geesthacht (Germany); Proefrock, Daniel [Helmholtz-Zentrum Geesthacht, Institute for Coastal Research, Department for Marine Bioanalytical Chemistry, Max-Planck Str. 1, D - 21502 Geesthacht (Germany); Hort, Norbert [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Department for Magnesium Processing, Max-Planck Str. 1, D - 21502 Geesthacht (Germany); Willumeit, Regine; Feyerabend, Frank [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Department for Structural Research on Macromolecules, Max-Planck Str. 1, D - 21502 Geesthacht (Germany)

2011-12-15

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.

Process for selectively concentrating the radioactivity of thorium containing magnesium slag

International Nuclear Information System (INIS)

Wilson, D.A.; Christiansen, S.H.; Simon, J.; Morin, D.W.

1993-01-01

In a process for separating magnesium from a magnesium slag using water and carbon dioxide, the improvement described comprises: (a) forming an aqueous magnesium slurry from the magnesium slag, which slag contains radioactive thorium and its daughters, and water; (b) solubilizing magnesium from the magnesium slurry by reacting the aqueous magnesium slurry with carbon dioxide wherein the carbon dioxide is at a pressure from greater than ambient to about 1,000 psig (about 7,000 kPa); (c) selectively concentrating by filtering the radioactive thorium and its daughters such that the radioactive thorium and its daughters are separated from the solubilized magnesium filtrate; and (d) reducing volume and/or weight of radioactive solids for disposal as radioactive waste

Magnesium Cermets and Magnesium-Beryllium Alloys; Cermets au magnesium et au magnesium-beryllium; Metallokeramicheskie magnievye i magnievo-berillievye splavy; Cermets de magnesio y aleaciones de magnesio y berillio

Energy Technology Data Exchange (ETDEWEB)

Ivanov, V. E.; Zelenskij, V. F.; Fajfer, S. I.; Zhdanov, S. M.; Maksimenko, V. I.; Savchenko, V. I. [Fiziko-Tekhnicheskij Institut an USSR, Khar' kov, SSSR (Russian Federation)

1963-11-15

The paper describes some results of work on the development of magnesium-magnesium oxide cermets and of super heat-resistant magnesiumberyllium alloys produced by powder metallurgical methods. The introduction of even a minute quantity of finely dispersed magnesium oxide into magnesium results in a strengthening of the material, the degree of which increases with increased magnesium oxide concentration, although variation of this concentration within the limits of 0.3 to 5 wt.% has a comparatively slight effect on the corresponding variation in the short-term strength over the whole range of temperatures investigated. At 20{sup o}C, in the case of the cermets, {sigma}{sub {beta}} = 28 to 31 kg/mm{sup 2} and {delta} = 3 .5 to 4.5%; at 500{sup o}C {sigma}{sub {beta}} = 2.6 to 3.2 kg/mm{sup 2} and {delta} =30 to 40%. The positive effect of the finely dispersed oxide phase is particularly evident in protracted tests. For magnesium cermets, {sigma} (300)/100 = 2.2 kg/mm{sup 2}. Characteristic of the mixtures is the high thermal stability of the strength properties, linked chiefly with the thermodynamic stability of the strength-giving oxide phase in the metal matrix. The use of powder metallurgical methods has yielded super heat-resistant magnesium-beryllium alloys containing heightened concentrations of beryllium (PMB alloys). In their strength characteristics PMB alloys are close to Mg-MgO cermets, but the magnesium-beryllium alloys have a degree and duration of resistance to high temperature oxidation which exceeds the corresponding qualities of the magnesium alloys at present known. Thus, in air of 580{sup o}C, PMB alloys with 2 to 5% beryllium maintain a high resistance to oxidation for a period of over 12000 to 14000 h. This long-term heat resistance is chiefly a result of the amount of beryllium in the alloy, and increases with increasing beryllium content. PMB alloys are also marked by high resistance to short bursts of overheating. Magnesium cermets and

Magnesium in Disease Prevention and Overall Health12

Science.gov (United States)

Volpe, Stella Lucia

2013-01-01

Magnesium is the fourth most abundant mineral and the second most abundant intracellular divalent cation and has been recognized as a cofactor for >300 metabolic reactions in the body. Some of the processes in which magnesium is a cofactor include, but are not limited to, protein synthesis, cellular energy production and storage, reproduction, DNA and RNA synthesis, and stabilizing mitochondrial membranes. Magnesium also plays a critical role in nerve transmission, cardiac excitability, neuromuscular conduction, muscular contraction, vasomotor tone, blood pressure, and glucose and insulin metabolism. Because of magnesium’s many functions within the body, it plays a major role in disease prevention and overall health. Low levels of magnesium have been associated with a number of chronic diseases including migraine headaches, Alzheimer’s disease, cerebrovascular accident (stroke), hypertension, cardiovascular disease, and type 2 diabetes mellitus. Good food sources of magnesium include unrefined (whole) grains, spinach, nuts, legumes, and white potatoes (tubers). This review presents recent research in the areas of magnesium and chronic disease, with the goal of emphasizing magnesium’s role in disease prevention and overall health. PMID:23674807

There is chronic latent magnesium deficiency in apparently healthy university students

OpenAIRE

Hermes Sales, Cristiane; Azevedo Nascimento, Débora; Queiroz Medeiros, Anna Cecília; Costa Lima, Kênio; Campos Pedrosa, Lucia Fátima; Colli, Célia

2014-01-01

Introduction: Magnesium is an essential micronutrient for human body, and its deficiency has been associated with risk of non-communicable diseases. Objective: Assessment of magnesium status, and evaluation of the frequency of magnesium deficiency in a group of healthy adults. Methods: Plasma and erythrocyte magnesium levels, and magnesium intake were determined in 115 students (55 women and 60 men), from a public university in Brazil. Results: The medians of magnesium concentration in plasma...

Direct-reading spectrochemical analysis of magnesium alloys

International Nuclear Information System (INIS)

Roca Adell, M.

1964-01-01

A Quantometer has been applied to the determination of aluminum, berylium, calcium, iron, silicon and zinc in magnesium alloys Magnox, after the conversion of the samples to the oxide. For the aluminum, whose concentration is relatively high, the conducting briquets technique with an interrupted discharge is employed, using the magnesium as the internal standard. For the other elements a total burning method with direct current arc is employed, using also the magnesium as the internal standard. (Author) 7 refs

Co3O4 nanoneedle@electroactive nickel boride membrane core/shell arrays: A novel hybrid for enhanced capacity

International Nuclear Information System (INIS)

Li, Tingting; Zhu, Congxu; Yang, Xiaogang; Gao, Yuanhao; He, Weiwei; Yue, Hongwei; Zhao, Hongxiao

2017-01-01

Graphical abstract: Active nickel boride membrane anchored Co 3 O 4 nanoneedle arrays hybrid is synthesized via rapid interface reaction. The optimized core/shell nanostructure demonstrates greatly enhanced electrochemical properties. Display Omitted -- Highlights: •Active nickel boride membrane anchored Co 3 O 4 nanoneedle arrays core-shell hybrid architectures was fabricated via rapid interface reaction. •Specific capacity was improved by synergy between highly active components and optimized electron transfer microstructure. •The assembled asymmetric supercapacitor device exhibited excellent electrochemical performance. -- Abstract: Exploring novel hybrid materials with efficient microstructure using facile approaches is highly urgent in designing supercapacitor electrodes. Here, the Ni-B membrane was used for coating the porous Co 3 O 4 nanoneedle arrays which supported on the nickel foam (NF) frameworks through a rapid chemical reduction process (denoted as NF/Co 3 O 4 @NiB). The Ni-B membrane both provided sufficient active sites for redox reactions and inhibited the aggregation of formed hybrid architectures. Benefiting from the unique structural design and strongly coupled effects between porous Co 3 O 4 arrays and Ni-B membrane, the resulted NF/Co 3 O 4 @NiB electrode exhibited high areal capacitance of 3.47 F cm −2 (0.48 mAh cm −2 ) at a current density of 2.5 mA cm −2 , an excellent rate capability while maintaining 95.5% capacity retention after 2000 cycles. The asymmetric supercapacitor constructed with the NF/Co 3 O 4 @NiB as positive electrode and hierarchical porous carbon (HPC) as negative electrode also showed ideal capacitive behavior, and simultaneously delivered high energy and power densities. The easily decoration of Ni-B membrane on various active nanoarrays may arouse more novel design about hybrid architectures for large-scale applications.

Constraints on Weathering from Riverine Magnesium Isotope Ratios

DEFF Research Database (Denmark)

Wiechert, Uwe; Ullmann, Clemens Vinzenz; Meixner, Anette

and industrialized regions, the d26Mg values mirror the lithologies of the catchment areas: the Danubian catchment is dominated by carbonatic lithologies and in the Danube dissolved magnesium exhibits the most negative d26Mg values between -1.85 and -1.70 ‰. The mainly siliceous catchment of the river Elbe causes....... Simple mass balance calculations on the basis of the magnesium isotopes obtained for the investigated rivers imply 26 to 59 % magnesium derived from carbonatic lithologies and 41 to 74 % magnesium from siliceous lithologies. This is in contrast to estimates using conventional methods for the tribute...

Total and ionized serum magnesium and calcium levels during magnesium sulfate administration for preterm labor

Science.gov (United States)

Kim, Won Hee; An, Yuna; Moon, Jong Ho; Noh, Eun Ji; Kim, Jong Woon

2018-01-01

Objective This study aimed to estimate the association between total and ionized magnesium, and the changes in serum magnesium and calcium levels in patients with preterm labor during magnesium sulfate (MgSO4) administration. Methods The study population included 64 women who were candidates for intravenous MgSO4 treatment for preterm labor. Serial blood samples were taken and measured total magnesium (T-Mg), ionized magnesium (I-Mg), total calcium (T-Ca), and ionized calcium (I-Ca) levels every one-week interval (1st, 2nd, 3rd). Results There was no significant difference in T-Mg and I-Mg levels during MgSO4 administration (P>0.05). There was no significant difference in T-Ca and I-Ca levels during MgSO4 administration (P>0.05). Compared before and after administration of MgSO4, T-Mg and I-Mg levels and T-Ca levels were changed allow statistically significant (P0.05). There was significant correlation between levels of I-Mg and T-Mg (I-Mg=0.395×T-Mg+0.144, P<0.01). Conclusion There were no significant differences in serum Mg and Ca levels during MgSO4 administration for preterm labor. Compared to the before and after administration of MgSO4, only I-Ca levels were not substantially changed. There are significant correlations between I-Mg and T-Mg levels during administration of MgSO4 and I-Mg level seemed to have more correlation with adverse effect than T-Mg. PMID:29372150

Magnesium analysis. Spectrophotometric determination of chromium

International Nuclear Information System (INIS)

Anon.

Chromium determination in magnesium used in uranium fabrication by magnesiothermics, applicable for chromium content between 2 to 10 ppm. Magnesium is dissolved in sulfuric acid, oxidized by potassium permanganate, the excess of permanganate is eliminated by sodium nitride. Spectrophotometry at 540 nm of the chromium (VI)-diphenylcarbazide complex [fr

Semi-solid twin-roll casting process of magnesium alloy sheets

International Nuclear Information System (INIS)

Watari, H.; Davey, K.; Rasgado, M.T. Alonso; Haga, T.; Koga, N.

2004-01-01

An experimental approach has been performed to ascertain the effectiveness of semi-solid strip casting using a horizontal twin roll caster. The demand for light-weight products with high strength has grown recently due to the rapid development of automobile and aircraft technology. One key to such development has been utilization of magnesium alloys, which can potentially reduce the total product weight. However, the problems of utilizing magnesium alloys are still mainly related to high manufacturing cost. One of the solutions to this problem is to develop magnesium casting-rolling technology in order to produce magnesium sheet products at competitive cost for commercial applications. In this experiment, magnesium alloy AZ31B was used to ascertain the effectiveness of semi-solid roll strip casting for producing magnesium alloy sheets. The temperature of the molten magnesium, and the roll speeds of the upper and lower rolls, (which could be changed independently), were varied to find an appropriate manufacturing condition. Rolling and heat treatment conditions were changed to examine which condition would be appropriate for producing wrought magnesium alloys with good formability. Microscopic observation of the crystals of the manufactured wrought magnesium alloys was performed. It has been found that a limiting drawing ratio of 2.7 was possible in a warm deep drawing test of the cast magnesium alloy sheets after being hot rolled

Features of solid solutions composition in magnesium with yttrium alloys

International Nuclear Information System (INIS)

Drits, M.E.; Rokhlin, L.L.; Tarytina, I.E.

1983-01-01

Additional data on features of yttrium solid solutions composition in magnesium in the course of their decomposition investigation in the case of aging are obtianed. The investigation has been carried out on the base of a binary magnesium-yttrium alloy the composition of which has been close to maximum solubility (at eutectic temperature) and magnesium-yttrium alloys additionally doped with zinc. It is shown that higher yttrium solubility in solid magnesium than it has been expected, issueing from the difference in atomic radii of these metals indicates electron yttrium-magnesium atoms interaction. In oversaturated magnesium-yttrium solid solutions at earlier decomposition stages Mg 3 Cd type ordering is observed. At aging temperatures up to 250 deg C and long exposures corresponding to highest strengthening in oversaturated magnesium yttrium solid solutions a rhombic crystal lattice phase with three symmetric orientations is formed

A Case of a Magnesium Oxide Bezoar.

Science.gov (United States)

Iwamuro, Masaya; Saito, Shunsuke; Yoshioka, Masao; Urata, Haruo; Ueda, Kumiko; Yamamoto, Kazuhide; Okada, Hiroyuki

2018-06-06

A 75-year-old Japanese woman presented with nausea and appetite loss. Computed tomography showed a radiopaque substance in the stomach. Esophagogastroduodenoscopy revealed bezoars in the stomach, which were endoscopically retrieved. The bezoars were mainly composed of magnesium and oxide. Although bezoar formation associated with magnesium oxide consumption is infrequently encountered, the present case indicates that pharmacobezoar should be considered among the differential diagnoses in patients who demonstrate a radiopaque mass in the digestive tract and have a history of magnesium oxide use.

Boride Formation Induced by pcBN Tool Wear in Friction-Stir-Welded Stainless Steels

Science.gov (United States)

Park, Seung Hwan C.; Sato, Yutaka S.; Kokawa, Hiroyuki; Okamoto, Kazutaka; Hirano, Satoshi; Inagaki, Masahisa

2009-03-01

The wear of polycrystalline cubic boron nitride (pcBN) tool and its effect on second phase formation were investigated in stainless steel friction-stir (FS) welds. The nitrogen content and the flow stress were analyzed in these welds to examine pcBN tool wear. The nitrogen content in stir zone (SZ) was found to be higher in the austenitic stainless steel FS welds than in the ferritic and duplex stainless steel welds. The flow stress of austenitic stainless steels was almost 1.5 times larger than that of ferritic and duplex stainless steels. These results suggest that the higher flow stress causes the severe tool wear in austenitic stainless steels, which results in greater nitrogen pickup in austenitic stainless steel FS welds. From the microstructural observation, a possibility was suggested that Cr-rich borides with a crystallographic structure of Cr2B and Cr5B3 formed through the reaction between the increased boron and nitrogen and the matrix during FS welding (FSW).

The low-lying quartet electronic states of group 14 diatomic borides XB (X = C, Si, Ge, Sn, Pb)

Science.gov (United States)

Pontes, Marcelo A. P.; de Oliveira, Marcos H.; Fernandes, Gabriel F. S.; Da Motta Neto, Joaquim D.; Ferrão, Luiz F. A.; Machado, Francisco B. C.

2018-04-01

The present work focuses in the characterization of the low-lying quartet electronic and spin-orbit states of diatomic borides XB, in which X is an element of group 14 (C, Si, Ge, Sn, PB). The wavefunction was obtained at the CASSCF/MRCI level with a quintuple-ζ quality basis set. Scalar relativistic effects were also taken into account. A systematic and comparative analysis of the spectroscopic properties for the title molecular series was carried out, showing that the (1)4Π→X4Σ- transition band is expected to be measurable by emission spectroscopy to the GeB, SnB and PbB molecules, as already observed for the lighter CB and SiB species.

Role of magnesium on the biomimetic deposition of calcium phosphate

Science.gov (United States)

Sarma, Bimal K.; Sarma, Bikash

2016-10-01

Biomimetic depositions of calcium phosphate (CaP) are carried out using simulated body fluid (SBF), calcifying solution and newly developed magnesium containing calcifying solution. Calcium phosphate has a rich phase diagram and is well known for its excellent biocompatibility and bioactivity. The most common phase is hydroxyapatite (HAp), an integral component of human bone and tooth, widely used in orthopedic and dental applications. In addition, calcium phosphate nanoparticles show promise for the targeted drug delivery. The doping of calcium phosphate by magnesium, zinc, strontium etc. can change the protein uptake by CaP nanocrystals. This work describes the role of magnesium on the nucleation and growth of CaP on Ti and its oxide substrates. X-ray diffraction studies confirm formation of HAp nanocrystals which closely resemble the structure of bone apatite when grown using SBF and calcifying solution. It has been observed that magnesium plays crucial role in the nucleation and growth of calcium phosphate. A low magnesium level enhances the crystallinity of HAp while higher magnesium content leads to the formation of amorphous calcium phosphate (ACP) phase. Interestingly, the deposition of ACP phase is rapid when magnesium ion concentration in the solution is 40% of calcium plus magnesium ions concentration. Moreover, high magnesium content alters the morphology of CaP films.

Magnesium and diltiazem relaxes phenylephrine-precontracted rat aortic rings

Science.gov (United States)

Dogan, Mustafa; Peker, Recep O.; Donmez, Soner; Gokalp, Osman

2012-01-01

Perioperative vasospasm during cardiovascular surgery is a challenging problem. Several vasodilator agents are frequently utilized for its prevention in surgical practice. Magnesium and diltiazem both have known potential vasorelaxant effects. We planned to compare the efficacy of diltiazem and magnesium in relieving phenylephrine-precontracted rat aortic rings. Ten young adult female Wistar albino rats weighing 230–260 g were used in this study. The aortic rings in the organ bath equilibrated and reached their baseline tension. Precontraction was induced by 0.001 mmol/l phenylephrine and cumulative concentration–relaxation curves were obtained by consecutively increasing the addition of either diltiazem (10−6-0.1 mmol/l) or magnesium (0.1–10 mmol/l). The mean maximal relaxation responses observed by diltiazem and magnesium on separate aortic rings were 90 ± 3 and 53 ± 2%, respectively. The calculated EC50 of diltiazem was 0.01035 mmol/l, whereas the EC50 of magnesium was 4.064 mmol/l (P < 0.05). Both magnesium and diltiazem produced vasorelaxation on phenylephrine-precontracted rat aortic rings in this study, but the potency of diltiazem regarding the EC50 value was significantly higher than that of magnesium. Magnesium could be a candidate together with diltiazem to inhibit vasospasm on arterial grafts during coronary bypass surgery. PMID:22523136

Telomere Homeostasis: Interplay with Magnesium

Directory of Open Access Journals (Sweden)

Donogh Maguire

2018-01-01

Full Text Available Telomere biology, a key component of the hallmarks of ageing, offers insight into dysregulation of normative ageing processes that accompany age-related diseases such as cancer. Telomere homeostasis is tightly linked to cellular metabolism, and in particular with mitochondrial physiology, which is also diminished during cellular senescence and normative physiological ageing. Inherent in the biochemistry of these processes is the role of magnesium, one of the main cellular ions and an essential cofactor in all reactions that use ATP. Magnesium plays an important role in many of the processes involved in regulating telomere structure, integrity and function. This review explores the mechanisms that maintain telomere structure and function, their influence on circadian rhythms and their impact on health and age-related disease. The pervasive role of magnesium in telomere homeostasis is also highlighted.

Yttrium ion implantation on the surface properties of magnesium

International Nuclear Information System (INIS)

Wang, X.M.; Zeng, X.Q.; Wu, G.S.; Yao, S.S.

2006-01-01

Owing to their excellent physical and mechanical properties, magnesium and its alloys are receiving more attention. However, their application has been limited to the high reactivity and the poor corrosion resistance. The aim of the study was to investigate the beneficial effects of ion-implanted yttrium using a MEVVA ion implanter on the surface properties of pure magnesium. Isothermal oxidation tests in pure O 2 at 673 and 773 K up to 90 min indicated that the oxidation resistance of magnesium had been significantly improved. Surface morphology of the oxide scale was analyzed using scanning electron microscope (SEM). Auger electron spectroscopy (AES) and X-ray diffraction (XRD) analyses indicated that the implanted layer was mainly composed of MgO and Y 2 O 3 , and the implanted layer with a duplex structure could decrease the inward diffusion of oxygen and reduce the outward diffusion of Mg 2+ , which led to improving the oxidation resistance of magnesium. Potentiodynamic polarization curves were used to evaluate the corrosion resistance of the implanted magnesium. The results show yttrium implantation could enhance the corrosion resistance of implanted magnesium compared with that of pure magnesium

Alloying principles for magnesium base heat resisting alloys

International Nuclear Information System (INIS)

Drits, M.E.; Rokhlin, L.L.; Oreshkina, A.A.; Nikitina, N.I.

1982-01-01

Some binary systems of magnesium-base alloys in which solid solutions are formed, are considered for prospecting heat resistant alloys. It is shown that elements having essential solubility in solid magnesium strongly decreasing with temperature should be used for alloying maqnesium base alloys with high strength properties at increased temperatures. The strengthening phases in these alloys should comprise essential quantity of magnesium and be rather refractory

40 CFR 721.9513 - Modified magnesium silicate polymer (generic).

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified magnesium silicate polymer... Specific Chemical Substances § 721.9513 Modified magnesium silicate polymer (generic). (a) Chemical... as modified magnesium silicate polymer (PMN P-98-604) is subject to reporting under this section for...

Effect of magnesium treatment and glucose levels on delayed cerebral ischemia in patients with subarachnoid hemorrhage: a substudy of the Magnesium in Aneurysmal Subarachnoid Haemorrhage trial (MASH-II).

Science.gov (United States)

Leijenaar, Jolien F; Dorhout Mees, Sanne M; Algra, Ale; van den Bergh, Walter M; Rinkel, Gabriel J E

2015-10-01

Magnesium treatment did not improve outcome in patients with aneurysmal subarachnoid haemorrhage in the Magnesium in Aneurysmal Subarachnoid Haemorrhage II trial. We hypothesized that high glucose levels may have offset a potential beneficial effect to prevent delayed cerebral ischemia. We investigated if magnesium treatment led to less delayed cerebral ischemia and if glucose levels interacted with magnesium treatment in the Magnesium in Aneurysmal Subarachnoid Haemorrhage II trial. To investigate the effect of magnesium treatment on occurrence of delayed cerebral ischemia and the interaction between glucose levels and magnesium treatment in subarachnoid hemorrhage patients. The Magnesium in Aneurysmal Subarachnoid Haemorrhage was a phase III randomized placebo-controlled trial assessing the effect of magnesium sulphate on clinical outcome in aneurysmal subarachnoid hemorrhage patients. For the current study, we included only the patients admitted to the University Medical Centre-Utrecht. We calculated hazard ratios for occurrence of delayed cerebral ischemia in patients treated with magnesium vs. placebo for the entire study population, and separately in the subgroups of patients with high and low mean fasting and mean daily glucose levels until onset of delayed cerebral ischemia. We used the cross-product of magnesium and glucose in the regression analysis to evaluate whether an interaction between magnesium and glucose existed. We included 616 patients: 307 received magnesium and 309 placebo; 156 patients had delayed cerebral ischemia. Hazard ratio for magnesium on occurrence of delayed cerebral ischemia was 1·0 (95% confidence interval: 0·7-1·4). Results were similar in patients with low or high fasting or daily glucose levels. We found no interactions between magnesium treatment and high fasting (P = 0·54) and daily glucose (P = 0·60). Magnesium treatment did not reduce the risk of delayed cerebral ischemia in patients with aneurysmal

Blood compatibility of magnesium and its alloys.

Science.gov (United States)

Feyerabend, Frank; Wendel, Hans-Peter; Mihailova, Boriana; Heidrich, Stefanie; Agha, Nezha Ahmad; Bismayer, Ulrich; Willumeit-Römer, Regine

2015-10-01

Blood compatibility analysis in the field of biomaterials is a highly controversial topic. Especially for degradable materials like magnesium and its alloys no established test methods are available. The purpose of this study was to apply advanced test methodology for the analysis of degrading materials to get a mechanistic insight into the corrosion process in contact with human blood and plasma. Pure magnesium and two magnesium alloys were analysed in a modified Chandler-Loop setup. Standard clinical parameters were determined, and a thorough analysis of the resulting implant surface chemistry was performed. The contact of the materials to blood evoked an accelerated inflammatory and cell-induced osteoconductive reaction. Corrosion products formed indicate a more realistic, in vivo like situation. The active regulation of corrosion mechanisms of magnesium alloys by different cell types should be more in the focus of research to bridge the gap between in vitro and in vivo observations and to understand the mechanism of action. This in turn could lead to a better acceptance of these materials for implant applications. The presented study deals with the first mechanistic insights during whole human blood contact and its influence on a degrading magnesium-based biomaterial. The combination of clinical parameters and corrosion layer analysis has been performed for the first time. It could be of interest due to the intended use of magnesium-based stents and for orthopaedic applications for clinical applications. An interest for the readers of Acta Biomaterialia may be given, as one of the first clinically approved magnesium-based devices is a wound-closure device, which is in direct contact with blood. Moreover, for orthopaedic applications also blood contact is of high interest. Although this is not the focus of the manuscript, it could help to rise awareness for potential future applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All

Enzymatic, urease-mediated mineralization of gellan gum hydrogel with calcium carbonate, magnesium-enriched calcium carbonate and magnesium carbonate for bone regeneration applications.

Science.gov (United States)

Douglas, Timothy E L; Łapa, Agata; Samal, Sangram Keshari; Declercq, Heidi A; Schaubroeck, David; Mendes, Ana C; der Voort, Pascal Van; Dokupil, Agnieszka; Plis, Agnieszka; De Schamphelaere, Karel; Chronakis, Ioannis S; Pamuła, Elżbieta; Skirtach, Andre G

2017-12-01

Mineralization of hydrogel biomaterials is considered desirable to improve their suitability as materials for bone regeneration. Calcium carbonate (CaCO 3 ) has been successfully applied as a bone regeneration material, but hydrogel-CaCO 3 composites have received less attention. Magnesium (Mg) has been used as a component of calcium phosphate biomaterials to stimulate bone-forming cell adhesion and proliferation and bone regeneration in vivo, but its effect as a component of carbonate-based biomaterials remains uninvestigated. In the present study, gellan gum (GG) hydrogels were mineralized enzymatically with CaCO 3 , Mg-enriched CaCO 3 and magnesium carbonate to generate composite biomaterials for bone regeneration. Hydrogels loaded with the enzyme urease were mineralized by incubation in mineralization media containing urea and different ratios of calcium and magnesium ions. Increasing the magnesium concentration decreased mineral crystallinity. At low magnesium concentrations calcite was formed, while at higher concentrations magnesian calcite was formed. Hydromagnesite (Mg 5 (CO 3 ) 4 (OH) 2 .4H 2 O) formed at high magnesium concentration in the absence of calcium. The amount of mineral formed and compressive strength decreased with increasing magnesium concentration in the mineralization medium. The calcium:magnesium elemental ratio in the mineral formed was higher than in the respective mineralization media. Mineralization of hydrogels with calcite or magnesian calcite promoted adhesion and growth of osteoblast-like cells. Hydrogels mineralized with hydromagnesite displayed higher cytotoxicity. In conclusion, enzymatic mineralization of GG hydrogels with CaCO 3 in the form of calcite successfully reinforced hydrogels and promoted osteoblast-like cell adhesion and growth, but magnesium enrichment had no definitive positive effect. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

The Magnesium Industry Today…The Global Perspective

Science.gov (United States)

Patzer, Greg

World demand for magnesium will show a decline in 2009. The outlook for 2010, which is guardedly optimistic, will be for a resumption of slow growth. The industry has seen marked changes in the sources of supply for primary and alloyed magnesium in recent years. Technological advances in magnesium continue at a strong pace as does interest in the material as a substitute for other light metals. The automotive segment remains the end-use area with the largest growth potential, if for no other reason than the size and quantity of the potential materials substitution applications. However, the shrinkage of that market, particularly in North America will have a definite impact on expectations for magnesium. The 3C market (computers, communications & consumer electronics) will continue to show above average growth. Other niche markets related to medical and construction industries also offer potential.

QUALITY OF YOGHURTS FROM GOAT'S MILK ENRICHED WITH MAGNESIUM CHLORIDE

Directory of Open Access Journals (Sweden)

Agata Znamirowska

2015-02-01

Full Text Available Goat’s milk can be enriched with magnesium in the form of chloride before pasteurization with a save dose, i.e. 20 mg of magnesium for 100 g of milk. Higher doses of magnesium can lead to coagulation of proteins since together with the increase of the dose of fortification there increases general acidity while pH of milk decreases. Together with the increase of the dose of fortification of yoghurts with magnesium there was shown an essential proportional increase of acidity and hardness of curds persisting for 21 days of storage. Enriching goat’s milk yoghurts with magnesium decreased the intensity of „goat” smell and aftertaste and did not cause a change in colour. The most favourable solution is the production of goat’s milk yoghurts enriched with 10-20 mg of magnesium in the form of magnesium chloride. Such doses of enrichment caused successive lowering of perceptibility of „goat” aftertaste and smell together with extension of storage time.

Serum Magnesium Levels in Non-Pregnant, Pregnant And Pre ...

African Journals Online (AJOL)

The objective of this study was to compare the serum magnesium levels in normal pregnancy and pregnancy complicated by pre-eclampsia since magnesium has been implicated in the pathogenesis of vascular dysfunction. We measured serum magnesium levels in patients with pre-eclampsia (n=36), patients with normal ...

Magnesium for Hydrogen Storage

DEFF Research Database (Denmark)

Vigeholm, B.; Kjøller, John; Larsen, Bent

1980-01-01

The reaction of hydrogen with commercially pure magnesium powder (above 99.7%) was investigated in the temperature range 250–400 °C. Hydrogen is readily sorbed above the dissociation pressure. During the initial exposure the magnesium powder sorbs hydrogen slowly below 400 °C but during the second...... that the particles do not disintegrate is explained by a sintering process at the working temperatures. Exposure to air does not impair the sorption ability; on the contrary, it appears that surface oxidation plays an important role in the reaction. Some handling problems, e.g. the reaction of the hydride with water...

Macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid

International Nuclear Information System (INIS)

Lidong, Wang; Yongliang, Ma; Wendi, Zhang; Qiangwei, Li; Yi, Zhao; Zhanchao, Zhang

2013-01-01

Graphical abstract: Ascorbic acid is used as an inhibitor to retard the oxidation rate of magnesium sulfite. It shows that the oxidation rate would decrease greatly with the rise of initial ascorbic acid concentration, which provides a useful reference for sulfite recovery in magnesia desulfurization. -- Highlights: • We studied the kinetics of magnesium sulfite oxidation inhibited by ascorbic acid. • The oxidation process was simulated by a three-phase model and proved by HPLC–MS. • We calculated the kinetic parameters of intrinsic oxidation of magnesium sulfite. -- Abstract: Magnesia flue gas desulfurization is a promising process for small to medium scale industrial coal-fired boilers in order to reduce sulfur dioxide emissions, in which oxidation control of magnesium sulfite is of great importance for the recycling of products. Effects of four inhibitors were compared by kinetic experiments indicating that ascorbic acid is the best additive, which retards the oxidation process of magnesium sulfite in trace presence. The macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid were studied. Effects of the factors, including ascorbic acid concentration, magnesium sulfite concentration, oxygen partial pressure, pH, and temperature, were investigated in a stirred reactor with bubbling. The results show that the reaction rate is −0.55 order in ascorbic acid, 0.77 in oxygen partial pressure, and zero in magnesium sulfite concentration, respectively. The apparent activation energy is 88.0 kJ mol −1 . Integrated with the kinetic model, it is concluded that the oxidation rate of magnesium sulfite inhibited by ascorbic acid is controlled by the intrinsic chemical reaction. The result provides a useful reference for sulfite recovery in magnesia desulfurization

Corrosion of magnesium and some magnesium alloys in gas cooled reactors; Corrosion du magnesium et de certains de ses alliages dans les piles refroidies par gaz

Energy Technology Data Exchange (ETDEWEB)

Caillat, R; Darras, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

The results of corrosion tests on magnesium and some magnesium alloys (Mg-Zr and Mg-Zr-Zn) in moist air (like G1 reactor) and in CO{sub 2}: (like G2, G3, EDF1 reactors) are reported. The maximum temperature for exposure of magnesium to moist air without any risk of corrosion is 350 deg. C. Indeed, the oxidation rate follows a linear law above 350 deg. C although it reaches a constant level and keeps on very low under 350 deg. C. However, as far as corrosion is concerned this temperature limit can be raised up to 500 deg. C if moist air is very slightly charged with fluorinated compounds. Under pressure of CO{sub 2}, these three materials oxidate much more slowly even if 500 deg. C is reached. The higher is the temperature, the higher is the constant level of the weight increase and the quicker is reached this one. However, Mg-Zr alloy behaves quite better than pure magnesium and especially than Mg-Zr-Zn alloy. (author)Fren. [French] On expose essentiellement les resultats d'etudes sur la corrosion du magnesium et de certains de ses alliages (Mg-Zr et Mg-Zr-Zn) dans l'air humide (cas de la pile G1) et dans le gaz carbonique (cas des piles G2, G3, EDF1, etc...). La temperature limite d'exposition du magnesium dans l'air humide sans risque de corrosion se situe a 350 deg. C; en effet l'oxydation a un caractere lineaire au-dessus de cette temperature, alors qu'elle atteint un palier et reste tres limitee au-dessous de 350 deg. C. Du point de vue de la corrosion, cette temperature limite d'emploi peut cependant etre elevee jusqu'a 500 deg. C si l'on introduit dans l'air humide de tres faibles teneurs de composes fluores. Dans le gaz carbonique sous pression, l'oxydation est beaucoup plus faible, meme jusqu'a 50g. C pour les trois materiaux: l'augmentation de poids atteint un palier d'autant plus eleve et ceci d'autant plus rapidement que la temperature est elle-meme plus elevee. Cependant, l'alliage Mg-Zr se comporte nettement mieux que le magnesium pur et surtout que l

Corrosion of magnesium and some magnesium alloys in gas cooled reactors; Corrosion du magnesium et de certains de ses alliages dans les piles refroidies par gaz

Energy Technology Data Exchange (ETDEWEB)

Caillat, R.; Darras, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

The results of corrosion tests on magnesium and some magnesium alloys (Mg-Zr and Mg-Zr-Zn) in moist air (like G1 reactor) and in CO{sub 2}: (like G2, G3, EDF1 reactors) are reported. The maximum temperature for exposure of magnesium to moist air without any risk of corrosion is 350 deg. C. Indeed, the oxidation rate follows a linear law above 350 deg. C although it reaches a constant level and keeps on very low under 350 deg. C. However, as far as corrosion is concerned this temperature limit can be raised up to 500 deg. C if moist air is very slightly charged with fluorinated compounds. Under pressure of CO{sub 2}, these three materials oxidate much more slowly even if 500 deg. C is reached. The higher is the temperature, the higher is the constant level of the weight increase and the quicker is reached this one. However, Mg-Zr alloy behaves quite better than pure magnesium and especially than Mg-Zr-Zn alloy. (author)Fren. [French] On expose essentiellement les resultats d'etudes sur la corrosion du magnesium et de certains de ses alliages (Mg-Zr et Mg-Zr-Zn) dans l'air humide (cas de la pile G1) et dans le gaz carbonique (cas des piles G2, G3, EDF1, etc...). La temperature limite d'exposition du magnesium dans l'air humide sans risque de corrosion se situe a 350 deg. C; en effet l'oxydation a un caractere lineaire au-dessus de cette temperature, alors qu'elle atteint un palier et reste tres limitee au-dessous de 350 deg. C. Du point de vue de la corrosion, cette temperature limite d'emploi peut cependant etre elevee jusqu'a 500 deg. C si l'on introduit dans l'air humide de tres faibles teneurs de composes fluores. Dans le gaz carbonique sous pression, l'oxydation est beaucoup plus faible, meme jusqu'a 50g. C pour les trois materiaux: l'augmentation de poids atteint un palier d'autant plus eleve et ceci d'autant plus rapidement que la temperature est elle-meme plus elevee. Cependant, l

Solid state cathode materials for secondary magnesium-ion batteries that are compatible with magnesium metal anodes in water-free electrolyte

International Nuclear Information System (INIS)

Crowe, Adam J.; Bartlett, Bart M.

2016-01-01

With high elemental abundance, large volumetric capacity, and dendrite-free metal deposition, magnesium metal anodes offer promise in beyond-lithium-ion batteries. However, the increased charge density associated with the divalent magnesium-ion (Mg 2+ ), relative to lithium-ion (Li + ) hinders the ion-insertion and extraction processes within many materials and structures known for lithium-ion cathodes. As a result, many recent investigations incorporate known amounts of water within the electrolyte to provide temporary solvation of the Mg 2+ , improving diffusion kinetics. Unfortunately with the addition of water, compatibility with magnesium metal anodes disappears due to forming an ion-insulating passivating layer. In this short review, recent advances in solid state cathode materials for rechargeable magnesium-ion batteries are highlighted, with a focus on cathode materials that do not require water contaminated electrolyte solutions for ion insertion and extraction processes. - Graphical abstract: In this short review, we present candidate materials for reversible Mg-battery cathodes that are compatible with magnesium metal in water-free electrolytes. The data suggest that soft, polarizable anions are required for reversible cycling.

Investigation of samarium solubility in the magnesium based solid solution

International Nuclear Information System (INIS)

Rokhlin, L.L.; Padezhnova, E.M.; Guzej, L.S.

1976-01-01

Electric resistance measurements and microscopic analysis were used to investigate the solubility of samarium in a magnesium-based solid solution. The constitutional diagram Mg-Sm on the magnesium side is of an eutectic type with the temperature of the eutectic transformation of 542 deg C. Samarium is partly soluble in solid magnesium, the less so, the lower is the temperature. The maximum solubility of samarium in magnesium (at the eutectic transformation point) is 5.8 % by mass (0.99 at. %). At 200 deg C, the solubility of samarium in magnesium is 0.4 % by mass (0.063 at. %)

Magnesium and related low alloys

International Nuclear Information System (INIS)

Bernard, J.; Caillat, R.; Darras, R.

1959-01-01

In the first part the authors examine the comparative corrosion of commercial magnesium, of a magnesium-zirconium alloy (0,4 per cent ≤ Zr ≤ 0,7 per cent) of a ternary magnesium-zinc-zirconium alloy (0,8 per cent ≤ Zn ≤ 1,2 per cent) and of english 'Magnox type' alloys, in dry carbon dioxide-free air, in damp carbon dioxide-free air, and in dry and damp carbon dioxide, at temperatures from 300 to 600 deg. C. In the second part the structural stability of these materials is studied after annealings, of 10 to 1000 hours at 300 to 450 deg. C. Variations in grain after these heat treatments and mechanical stretching properties at room temperature are presented. Finally various creep rate and life time diagrams are given for these materials, for temperatures ranging from 300 to 450 deg. C. (author) [fr

Comparison of Serum Calcium and Magnesium Between ...

African Journals Online (AJOL)

Background: Evidence suggests the involvement of calcium and magnesium metabolism in the pathophysiology of preeclampsia. However, findings from studies are heterogenous and inconsistent. Aim: The study aimed to compare the total serum calcium and magnesium levels in preeclamptic women with that of ...

Justification for intravenous magnesium therapy in acute myocardial infarction

DEFF Research Database (Denmark)

Rasmussen, H S

1988-01-01

Recent studies have shown that patients with acute myocardial infarction (AMI) are magnesium-deficient and develop an additional transient decrease in serum magnesium concentrations (S-Mg c) during the acute phase of the infarct. Animal experiments, as well as studies on humans, have indicated.......v. magnesium therapy on mortality and incidence of arrhythmias in patients with AMI has been evaluated. Magnesium treatment more than halved the acute mortality and incidence of arrhythmias requiring treatment in three of the four intervention studies. The mechanisms behind the beneficial effect of magnesium...... therapy are probably multifactorial; a direct depressive effect on the cardiac conducting system; a peripheral dilatory effect on the arteries, reducing the afterload on the myocardium; a reduced infarct size; an ion-stabilizing effect, maintaining stable intra and extracellular concentrations...

Magnesium Borate Synthesis by Microwave Energy: A New Method

Directory of Open Access Journals (Sweden)

Azmi Seyhun Kipcak

2013-01-01

Full Text Available Magnesium borates are one of the major groups of boron minerals that have important properties such as high heat and corrosion resistances and high coefficients of elasticity. In this study, magnesium borate minerals are synthesized using boric acid and magnesium oxide with a new method of microwave, and the synthesized minerals are characterized by various analysis techniques. The results show that pure, “magnesium borate hydrate” minerals are obtained at the end of various steps. The characterization of the products is determined with the techniques of X-Ray Diffraction (XRD, Fourier Transform Infrared Spectroscopy (FT-IR, Raman Spectroscopy, and Scanning Electron Microscopy (SEM. Additionally, overall “magnesium borate hydrate” yields are calculated and found about 67% at 270 W, 8 minutes and 360 W, 3 minutes of reaction times, respectively.

New ternary tantalum borides containing boron dumbbells: Experimental and theoretical studies of Ta2OsB2 and TaRuB

International Nuclear Information System (INIS)

Mbarki, Mohammed; Touzani, Rachid St.; Rehorn, Christian W.G.; Gladisch, Fabian C.; Fokwa, Boniface P.T.

2016-01-01

The new ternary transition metal-rich borides Ta 2 OsB 2 and TaRuB have been successfully synthesized by arc-melting the elements in a water-cooled crucible under an argon atmosphere. The crystal structures of both compounds were solved by single-crystal X-ray diffraction and their metal compositions were confirmed by EDX analysis. It was found that Ta 2 OsB 2 and TaRuB crystallize in the tetragonal Nb 2 OsB 2 (space group P4/mnc, no. 128) and the orthorhombic NbRuB (space group Pmma, no. 51) structure types with lattice parameters a=5.878(2) Å, c=6.857(2) Å and a=10.806(2) Å, b=3.196(1) Å, c=6.312(2) Å, respectively. Furthermore, crystallographic, electronic and bonding characteristics have been studied by density functional theory (DFT). Electronic structure relaxation has confirmed the crystallographic parameters while COHP bonding analysis indicates that B 2 -dummbells are the strongest bonds in both compounds. Moreover, the formation of osmium dumbbells in Ta 2 OsB 2 through a Peierls distortion along the c-axis, is found to be the origin of superstructure formation. Magnetic susceptibility measurements reveal that the two phases are Pauli paramagnets, thus confirming the theoretical DOS prediction of metallic character. Also hints of superconductivity are found in the two phases, however lack of single phase samples has prevented confirmation. Furthermore, the thermodynamic stability of the two modifications of AMB (A=Nb, Ta; M =Ru, Os) are studied using DFT, as new possible phases containing either B 4 - or B 2 -units are predicted, the former being the most thermodynamically stable modification. - Graphical abstract: The two new ternary tantalum borides, Ta 2 OsB 2 and TaRuB, have been discovered. Their crystal structures contain boron dumbbells, which are the strongest bonds. Peirls distortion is found responsible for Os 2 -dumbbells formation in Ta 2 OsB 2 . Ta 2 OsB 2 and TaRuB are Pauli paramagnet and potential superconductors. - Highlights: �

Magnesium in diet

Science.gov (United States)

... sources of magnesium: Fruits or vegetables (such as bananas, dried apricots, and avocados) Nuts (such as almonds ... deficiency: Low blood calcium level (hypocalcemia) Low blood potassium level (hypokalemia) Recommendations These are the recommended daily ...

Is serum magnesium estimate necessary in patients with Eclampsia ...

African Journals Online (AJOL)

The therapeutic index of magnesium is said to be low, hence, there are fears of toxicity when used as anticonvulsant in eclamptic patients. The objective of this study was to determine the serum levels of magnesium in eclamptic patients treated with magnesium sulphate and relate the levels with clinical indicators. It was a ...

Magnesium removal in the electrolytic zinc industry

NARCIS (Netherlands)

Booster, J.L.

2003-01-01

Electrolytic zinc plants need to take measures to control the magnesium content in their process liquors, because the natural magnesium bleed does not balance the input from concentrates. Presently used methods are environmentally unfriendly (due to the production of large amounts of waste gypsum)

Machinability of magnesium and aluminium alloys. Part I: cutting resistance

International Nuclear Information System (INIS)

Balout, B.; Songmene, V.; Masounave, J.

2002-01-01

Aluminium (2.7 g/cm 3 ) and magnesium (1.7 g/cm 3 ) are two competing light metals with similar mechanical properties and excellent possibilities for recycling. The forming of magnesium is often seen as an impediment to its use. New forming techniques using magnesium shavings are being developed, particularly in Japan. The machining of magnesium alloys by removal of metal raises safety concerns (risk of fire), which limits many potential applications of magnesium. The purpose of this work is to clarify and compare the machining properties of these two types of metal and better understand the mechanisms that may explain the differences in behaviour. Such a comparison could eventually provide an estimate of the cost of producing shavings for the manufacture of aluminium and magnesium parts through forging and extrusion, which would limit environmental pollution. Based on an analysis of cutting resistance during machining, it was demonstrated that magnesium alloys are easier to machine than similar aluminium alloys. Magnesium shavings are shorter than those of 6061-T6, but are especially more regular than those of A356, and their size is independent of cutting speed. It was also demonstrated that the fragility of materials can be characterized based on the results of cutting resistance produced during drilling

Magnesium and manganese content of halophilic bacteria

International Nuclear Information System (INIS)

de Medicis, E.; Paquette, J.; Gauthier, J.J.; Shapcott, D.

1986-01-01

Magnesium and manganese contents were measured by atomic absorption spectrophotometry in bacteria of several halophilic levels, in Vibrio costicola, a moderately halophilic eubacterium growing in 1 M NaCl, Halobacterium volcanii, a halophilic archaebacterium growing in 2.5 NaCl, Halobacterium cutirubrum, an extremely halophilic archaebacterium growing in 4 M NaCl, and Escherichia coli, a nonhalophilic eubacterium growing in 0.17 M NaCl. Magnesium and manganese contents varied with the growth phase, being maximal at the early log phase. Magnesium and manganese molalities in cell water were shown to increase with the halophilic character of the logarithmically growing bacteria, from 30 mmol of Mg per kg of cell water and 0.37 mmol of Mn per kg of cell water for E. coli to 102 mmol of Mg per kg of cell water and 1.6 mmol of Mn per kg of cell water for H cutirubrum. The intracellular concentrations of manganese were determined independently by a radioactive tracer technique in V. costicola and H. volcanii. The values obtained by 54 Mn loading represented about 70% of the values obtained by atomic absorption. The increase of magnesium and manganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation

Effects of extracellular magnesium on the differentiation and function of human osteoclasts.

Science.gov (United States)

Wu, Lili; Luthringer, Bérengère J C; Feyerabend, Frank; Schilling, Arndt F; Willumeit, Regine

2014-06-01

Magnesium-based implants have been shown to influence the surrounding bone structure. In an attempt to partially reveal the cellular mechanisms involved in the remodelling of magnesium-based implants, the influence of increased extracellular magnesium content on human osteoclasts was studied. Peripheral blood mononuclear cells were driven towards an osteoclastogenesis pathway via stimulation with receptor activator of nuclear factor kappa-B ligand and macrophage colony-stimulating factor for 28 days. Concomitantly, the cultures were exposed to variable magnesium concentrations (from either magnesium chloride or magnesium extracts). Osteoclast proliferation and differentiation were evaluated based on cell metabolic activity, total protein content, tartrate-resistant acid phosphatase activity, cathepsin K and calcitonin receptor immunocytochemistry, and cellular ability to form resorption pits. While magnesium chloride first enhanced and then opposed cell proliferation and differentiation in a concentration-dependent manner (peaking between 10 and 15mM magnesium chloride), magnesium extracts (with lower magnesium contents) appeared to decrease cell metabolic activity (≈50% decrease at day 28) while increasing osteoclast activity at a lower concentration (twofold higher). Together, the results indicated that (i) variations in the in vitro extracellular magnesium concentration affect osteoclast metabolism and (ii) magnesium extracts should be used preferentially in vitro to more closely mimic the in vivo environment. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Magnesium borate radiothermoluminescent detectors

International Nuclear Information System (INIS)

Kazanskaya, V.A.; Kuzmin, V.V.; Minaeva, E.E.; Sokolov, A.D.

1974-01-01

In the report the technology of obtaining polycrystalline magnesium borate activated by dysprosium is described briefly and the method of preparing the tabletted detectors from it is presented. The dependence of the light sum of the samples on the proportion of the components and on the sintering regime has shown that the most sensitive material is obtained at the proportion of boric anhydride and magnesium oxide 2.2-2.4 and at the dysprosium concentration about 1 milligram-atom per gram molecule of the base. The glow curve of such a material has a simple form with one peak the maximum of which is located at 190-200 0 C. The measurement of the main dosimetric characteristics of the magnesium borate tabletted detectors and the comparison with similar parmaeters of the lithium fluoride tabletted detectors have shown that at practically identical effective number the former detectors have the following substantial advantages: the sensitivity is ten-twenty times as large, they are substantially more technological on synthesis of the radiothermoluminophor and during the production of the tabletted detectors, they have a simple glow curve, they do not require the utilization of the thermocycling during the use. (author)

Fatigue Analysis of Magnesium Alloys Components for Car Industry

Science.gov (United States)

Marsavina, Liviu; Rusu, Lucian; Șerban, Dan Andrei; Negru, Radu Marcel; Cernescu, Anghel

2017-12-01

The use of magnesium alloys in the automotive industry increased in the last decade because of their low weight and relative good mechanical properties. However, the variable loading conditions require a good fatigue behavior. This paper summaries the fatigue properties of magnesium alloys and presents new fatigue curve results for die cast AM50 magnesium alloy.

Unphysiologically high magnesium concentrations support chondrocyte proliferation and redifferentiation.

Science.gov (United States)

Feyerabend, Frank; Witte, Frank; Kammal, Michael; Willumeit, Regine

2006-12-01

The effect of unphysiologically high extracellular magnesium concentrations on chondrocytes, induced by the supplementation of magnesium sulfate, was studied using a 3-phase tissue engineering model. The experiments showed that chondrocyte proliferation and redifferentiation, on the gene and protein expression level, are enhanced. A negative influence was found during chondrogenesis where an inhibition of extracellular matrix formation was observed. In addition, a direct impact on chondrocyte metabolism, elevated magnesium concentrations also affected growth factor effectiveness by consecutive influences during chondrogenesis. All observations were dosage dependent. The results of this study indicate that magnesium may be a useful tool for cartilage tissue engineering.

Magnesium supplementation in children with attention deficit ...

African Journals Online (AJOL)

Background: Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder with associated mineral deficiency. Aim: To assess magnesium level in ADHD children and compare it to the normal levels in children. Then, to detect the effect of magnesium supplementation as an add on therapy, ...

Design Considerations for Developing Biodegradable Magnesium Implants

Science.gov (United States)

Brar, Harpreet S.; Keselowsky, Benjamin G.; Sarntinoranont, Malisa; Manuel, Michele V.

The integration of biodegradable and bioabsorbable magnesium implants into the human body is a complex undertaking that faces major challenges. The complexity arises from the fact that biomaterials must meet both engineering and physiological requirements to ensure the desired properties. Historically, efforts have been focused on the behavior of commercial magnesium alloys in biological environments and their resultant effect on cell-mediated processes. Developing causal relationships between alloy chemistry and micro structure, and its effect on cellular behavior can be a difficult and time intensive process. A systems design approach driven by thermodynamics has the power to provide significant contributions in developing the next generation of magnesium alloy implants with controlled degradability, biocompatibility, and optimized mechanical properties, at reduced time and cost. This approach couples experimental research with theory and mechanistic modeling for the accelerated development of materials. The aim of this article is to enumerate this strategy, design considerations and hurdles for developing new magnesium alloys for use as biodegradable implant materials [1].

Selectivity coefficients of ion-selective magnesium electrodes used for simultaneous determination of magnesium and calcium ions.

Science.gov (United States)

Maj-Zurawska, Magdalena; Lewenstam, Andrzej

2011-12-15

Membrane ion-selective magnesium electrodes are commonly used to determine ionized magnesium concentration in blood serum and intracellular fluid by potentiometric clinical analyzers. The selectivity of these electrodes against calcium ion is typically insufficient to avoid calcium interference in blood serum analysis. For this reason the selectivity coefficient for calcium ion has to be studied to make possible any mathematical corrections for calcium ion influence. Existing methods relate to the thermodynamic concept of ISE response which suggest a single constant value of the selectivity coefficient and slope that are stable over the concentration ranges of calcium and magnesium ions in the samples. Unfortunately, this rarely happens, and we rather observe dependences on solution and membrane composition, readout time, matrices (anticoagulant, vial coats) that justify usage of apparent selectivities and slopes. To get the practical insight into the response of magnesium ion-selective electrodes a novel method for estimating the selectivity coefficients and the slope of the electrode characteristics is proposed. This method is an effective starting point for selecting electrodes and designing transient signal software in a potentiometric clinical analyzer. The method allows obtaining the ionized magnesium concentration in blood serum with minimal possible error by addressing the assessed targets, i.e. apparent selectivity and slope. The method is based on computer simulation and on the Nicolsky-Eisenman equation. Usually only a few iterations are needed to obtain stable congruent results. The method presented is particularly useful in conditions where is not possible to obtain calibration curve, which is typical for clinical analyzer where at most three point calibration is performed. Copyright © 2011 Elsevier B.V. All rights reserved.

Biodegradable magnesium nanoparticle-enhanced laser hyperthermia therapy

Directory of Open Access Journals (Sweden)

Wang Q

2012-08-01

Full Text Available Qian Wang,1 Liping Xie,1 Zhizhu He,2 Derui Di,2 Jing Liu1,21Department of Biomedical Engineering, School of Medicine, Tsinghua University, 2Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, People's Republic of ChinaBackground: Recently, nanoparticles have been demonstrated to have tremendous merit in terms of improving the treatment specificity and thermal ablation effect on tumors. However, the potential toxicity and long-term side effects caused by the introduced nanoparticles and by expelling them out of the body following surgery remain a significant challenge. Here, we propose for the first time to directly adopt magnesium nanoparticles as the heating enhancer in laser thermal ablation to avoid these problems by making full use of the perfect biodegradable properties of this specific material.Methods: To better understand the new nano “green” hyperthermia modality, we evaluated the effects of magnesium nanoparticles on the temperature transients inside the human body subject to laser interstitial heating. Further, we experimentally investigated the heating enhancement effects of magnesium nanoparticles on a group of biological samples: oil, egg white, egg yolk, in vitro pig tissues, and the in vivo hind leg of rabbit when subjected to laser irradiation.Results: Both the theoretical simulations and experimental measurements demonstrated that the target tissues injected with magnesium nanoparticles reached much higher temperatures than tissues without magnesium nanoparticles. This revealed the enhancing behavior of the new nanohyperthermia method.Conclusion: Given the unique features of magnesium nanoparticles – their complete biological safety and ability to enhance heating – which most other advanced metal nanoparticles do not possess, the use of magnesium nanoparticles in hyperthermia therapy offers an important “green” nanomedicine modality for treating tumors

Magnesium Counteracts Vascular Calcification: Passive Interference or Active Modulation?

Science.gov (United States)

Ter Braake, Anique D; Shanahan, Catherine M; de Baaij, Jeroen H F

2017-08-01

Over the last decade, an increasing number of studies report a close relationship between serum magnesium concentration and cardiovascular disease risk in the general population. In end-stage renal disease, an association was found between serum magnesium and survival. Hypomagnesemia was identified as a strong predictor for cardiovascular disease in these patients. A substantial body of in vitro and in vivo studies has identified a protective role for magnesium in vascular calcification. However, the precise mechanisms and its contribution to cardiovascular protection remain unclear. There are currently 2 leading hypotheses: first, magnesium may bind phosphate and delay calcium phosphate crystal growth in the circulation, thereby passively interfering with calcium phosphate deposition in the vessel wall. Second, magnesium may regulate vascular smooth muscle cell transdifferentiation toward an osteogenic phenotype by active cellular modulation of factors associated with calcification. Here, the data supporting these major hypotheses are reviewed. The literature supports both a passive inorganic phosphate-buffering role reducing hydroxyapatite formation and an active cell-mediated role, directly targeting vascular smooth muscle transdifferentiation. However, current evidence relies on basic experimental designs that are often insufficient to delineate the underlying mechanisms. The field requires more advanced experimental design, including determination of intracellular magnesium concentrations and the identification of the molecular players that regulate magnesium concentrations in vascular smooth muscle cells. © 2017 American Heart Association, Inc.

Anti-scratch AlMgB14 Gorilla® Glass coating

Science.gov (United States)

Putrolaynen, V. V.; Grishin, A. M.; Rigoev, I. V.

2017-10-01

Hard aluminum-magnesium boride (BAM) films were fabricated onto Corning® Gorilla® Glass by radio-frequency magnetron sputtering of a single stoichiometric AlMgB14 target. BAM films exhibit a Vickers hardness from 10 to 30 GPa and a Young's modulus from 80 to 160 GPa depending on applied loading forces. Deposited hard coating increases the critical load at which glass substrate cracks. The adhesion energy of BAM films on Gorilla® Glass is 6.4 J/m2.

Ultra-hard AlMgB14 coatings fabricated by RF magnetron sputtering from a stoichiometric target

Science.gov (United States)

Grishin, A. M.; Khartsev, S. I.; Böhlmark, J.; Ahlgren, M.

2015-01-01

For the first time hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric ceramic AlMgB14 target. Optimized processing conditions (substrate temperature, target sputtering power and target-to-substrate distance) enable fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young's modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 and 275 GPa at 200 nm depth in 2 μm thick film.

X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection, and neoplasia disease: a combined immune deficiency with magnesium defect.

Science.gov (United States)

Ravell, Juan; Chaigne-Delalande, Benjamin; Lenardo, Michael

2014-12-01

To describe the role of the magnesium transporter 1 (MAGT1) in the pathogenesis of 'X-linked immunodeficiency with magnesium defect, Epstein-Barr virus (EBV) infection, and neoplasia' (XMEN) disease and its clinical implications. The magnesium transporter protein MAGT1 participates in the intracellular magnesium ion (Mg) homeostasis and facilitates a transient Mg influx induced by the activation of the T-cell receptor. Loss-of-function mutations in MAGT1 cause an immunodeficiency named 'XMEN syndrome', characterized by CD4 lymphopenia, chronic EBV infection, and EBV-related lymphoproliferative disorders. Patients with XMEN disease have impaired T-cell activation and decreased cytolytic function of natural killer (NK) and CD8 T cells because of decreased expression of the NK stimulatory receptor 'natural-killer group 2, member D' (NKG2D). Patients may have defective specific antibody responses secondary to T cell dysfunction, but B cells have not been shown to be directly affected by mutations in MAGT1. XMEN disease has revealed a novel role for free intracellular magnesium in the immune system. Further understanding of the MAGT1 signaling pathway may lead to new diagnostic and therapeutic approaches.

Serum magnesium and the risk of prediabetes: a population-based cohort study.

Science.gov (United States)

Kieboom, Brenda C T; Ligthart, Symen; Dehghan, Abbas; Kurstjens, Steef; de Baaij, Jeroen H F; Franco, Oscar H; Hofman, Albert; Zietse, Robert; Stricker, Bruno H; Hoorn, Ewout J

2017-05-01

Previous studies have found an association between serum magnesium and incident diabetes; however, this association may be due to reverse causation, whereby diabetes may induce urinary magnesium loss. In contrast, in prediabetes (defined as impaired fasting glucose), serum glucose levels are below the threshold for urinary magnesium wasting and, hence, unlikely to influence serum magnesium levels. Thus, to study the directionality of the association between serum magnesium levels and diabetes, we investigated its association with prediabetes. We also investigated whether magnesium-regulating genes influence diabetes risk through serum magnesium levels. Additionally, we quantified the effect of insulin resistance in the association between serum magnesium levels and diabetes risk. Within the population-based Rotterdam Study, we used Cox models, adjusted for age, sex, lifestyle factors, comorbidities, kidney function, serum levels of electrolytes and diuretic use, to study the association between serum magnesium and prediabetes/diabetes. In addition, we performed two mediation analyses: (1) to study if common genetic variation in eight magnesium-regulating genes influence diabetes risk through serum magnesium levels; and (2) to quantify the proportion of the effect of serum magnesium levels on diabetes that is mediated through insulin resistance (quantified by HOMA-IR). A total of 8555 participants (mean age, 64.7 years; median follow-up, 5.7 years) with normal glucose levels (mean ± SD: 5.46 ± 0.58 mmol/l) at baseline were included. A 0.1 mmol/l decrease in serum magnesium level was associated with an increase in diabetes risk (HR 1.18 [95% CI 1.04, 1.33]), confirming findings from previous studies. Of interest, a similar association was found between serum magnesium levels and prediabetes risk (HR 1.12 [95% CI 1.01, 1.25]). Genetic variation in CLDN19, CNNM2, FXYD2, SLC41A2, and TRPM6 significantly influenced diabetes risk (p prediabetes 13.4% was

Casting Porosity-Free Grain Refined Magnesium Alloys

Energy Technology Data Exchange (ETDEWEB)

Schwam, David [Case Western Reserve University

2013-08-12

The objective of this project was to identify the root causes for micro-porosity in magnesium alloy castings and recommend remedies that can be implemented in production. The findings confirm the key role played by utilizing optimal gating and risering practices in minimizing porosity in magnesium castings. 

Biodegradable magnesium-alloy stent:current situation in research

International Nuclear Information System (INIS)

Chen Hua; Zhao Xianxian

2011-01-01

In recent years, permanent metal stents are employed in the majority of interventional therapies; nevertheless, such kind of stents carries the problems of thrombosis and restenosis. Therefore, the biodegradable magnesium alloy stent has become the focus of attention. Theoretically, it has overcome the problems caused by permanent metal stents, so it is the development direction to use the biodegradable magnesium alloy in future. The authors believe that biodegradable magnesium alloy stents will be widely used in interventional procedures for many diseases. (authors)

Lithium/magnesium oxide catalyst and method of making

Energy Technology Data Exchange (ETDEWEB)

Lunsford, J.H.; Hinson, P.G.

1991-07-16

This patent describes a method for preparing a catalyst which is effective for converting methane to ethane and ethylene. It comprises mixing a solution of a magnesium alkoxide in an alcohol with a solution containing a source of lithium in an alcohol, to obtain a ratio of magnesium metal to lithium metal; hydrolyzing the magnesium alkoxide in the solution to form a gel; and calcining the gel to form a catalyst which is effective for converting methane to ethane and ethylene.

Cytotoxic effect of galvanically coupled magnesium-titanium particles.

Science.gov (United States)

Kim, Jua; Gilbert, Jeremy L

2016-01-01

Recent work has shown that reduction reactions at metallic biomaterial surfaces can induce significant killing of cells in proximity to the surface. To exploit this phenomenon for therapeutic purposes, for example, for cancer tumor killing or antibacterial effects (amongst other applications), magnesium metal particles, galvanically coupled to titanium by sputtering, have been evaluated for their cell-killing capability (i.e. cytotoxicity). Magnesium (Mg) particles large enough to prevent particle phagocytosis were investigated, so that only electrochemical reactions, and not particle toxicity per se, caused cytotoxic effects. Titanium (Ti) coated magnesium particles, as well as magnesium-only particles were introduced into MC3T3-E1 mouse pre-osteoblast cell cultures over a range of particle concentrations, and cells were observed to die in a dosage-dependent manner. Ti-coated magnesium particles killed more cells at lower particle concentration than magnesium alone (Pmagnesium and magnesium-titanium had no significant difference at similar particle concentrations. Complete cell killing occurred at 750μg/ml and 1500μg/ml for Mg-Ti and Mg, respectively. Thus, this work demonstrates that galvanically coupled Mg-Ti particles have a significant cell killing capability greater than Mg alone. In addition, when the pH associated with complete killing with particles was created using NaOH only (no particles), then the percentage of cells killed was significantly less (Pmagnesium-titanium microparticles kill cells more effectively than magnesium particles alone. The killing effect was shown to not be due to pH shifts since no differences were seen for different particle types and pH adjusted medium without particles did not exhibit the same level of killing. The significance of this work is the recognition of this killing effect with Mg particles and the potential therapeutic applications in infection control and cancer treatment that this process may provide. Copyright �

Impurity characterization of magnesium diuranate using simultaneous TG–DTA–FTIR measurements

Energy Technology Data Exchange (ETDEWEB)

Raje, Naina, E-mail: nraje@barc.gov.in [Analytical Chemistry Division, B.A.R.C., Mumbai 400 085 (India); Ghonge, Darshana K. [Analytical Chemistry Division, B.A.R.C., Mumbai 400 085 (India); Hemantha Rao, G.V.S. [NFC, ECIL Post, Hyderabad (India); Reddy, A.V.R. [Analytical Chemistry Division, B.A.R.C., Mumbai 400 085 (India)

2013-05-15

Current studies describe the application of simultaneous thermogravimetry–differential thermal analysis – evolved gas analysis techniques for the compositional characterization of magnesium diuranate (MDU) with respect to the impurities present in the matrix. The stoichiometric composition of MDU was identified as MgU{sub 2}O{sub 7}⋅3H{sub 2}O. Presence of carbonate and sulphate as impurities in the matrix was confirmed through the evolved gas analysis using Fourier Transformation Infrared Spectrometry detection. Carbon and magnesium hydroxide content present as impurities in magnesium diuranate have been determined quantitatively using TG and FTIR techniques and the results are in good agreement. Powder X-ray diffraction analysis of magnesium diuranate suggests the presence of magnesium hydroxide as impurity in the matrix. Also these studies confirm the formation of magnesium uranate, uranium sesquioxide and uranium dioxide above 1000 °C, due to the decomposition of magnesium diuranate.

Multivariate regression models for the simultaneous quantitative analysis of calcium and magnesium carbonates and magnesium oxide through drifts data

Directory of Open Access Journals (Sweden)

Marder Luciano

2006-01-01

Full Text Available In the present work multivariate regression models were developed for the quantitative analysis of ternary systems using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS to determine the concentration in weight of calcium carbonate, magnesium carbonate and magnesium oxide. Nineteen spectra of standard samples previously defined in ternary diagram by mixture design were prepared and mid-infrared diffuse reflectance spectra were recorded. The partial least squares (PLS regression method was applied to the model. The spectra set was preprocessed by either mean-centered and variance-scaled (model 2 or mean-centered only (model 1. The results based on the prediction performance of the external validation set expressed by RMSEP (root mean square error of prediction demonstrated that it is possible to develop good models to simultaneously determine calcium carbonate, magnesium carbonate and magnesium oxide content in powdered samples that can be used in the study of the thermal decomposition of dolomite rocks.

Preparation of plate-shape nano-magnesium hydroxide from asbestos tailings

International Nuclear Information System (INIS)

Du Gaoxiang; Zheng Shuilin

2009-01-01

To prepare magnesium hydroxide is one of the effective methods to the comprehensive utilization of asbestos tailings. Nano-scale magnesium hydroxide was prepared and mechanisms of in-situ surface modification were characterized in the paper. Process conditions of preparation of magnesium hydroxide from purified hydrochloric acid leachate of asbestos tailings were optimized and in-situ surface modification of the product was carried out. Results showed that optimum process conditions for preparing nano-scale magnesium hydroxide were as follows: initial concentration of Mg 2+ in the leachate was 22.75g/L, precipitant was NaOH solution (mass concentration 20%), reaction temperature was 50 deg. C, and reaction time was 5min. The diameter and thickness of the plate nano-scale magnesium hydroxide powder prepared under optimal conditions were about 100 nm and 10 nm, respectively. However, particle agglomeration was obvious, the particle size increased to micron-grade. Dispersity of the magnesium hydroxide powder could be elevated by in-situ modification by silane FR-693, titanate YB-502 and polyethylene glycol and optimum dosages were 1.5%, 1.5% and 0.75% of the mass of magnesium hydroxide, respectively. All of the modifiers adsorbed chemically on surfaces of magnesium hydroxide particles, among which Si-O-Mg bonds formed among silane FR-693 and the particle surfaces and Ti-O-Mg among titanate YB-502 and the surfaces.

Separation of radionuclides from water by magnesium oxide adsorption

International Nuclear Information System (INIS)

Tseng, Chia-Lian; Lo, Jem-Mau; Yeh, Si-Jung

1987-01-01

Adsorption by magnesium oxide of more than forty radionuclides in respective ionic species in water was observed. Generally, the radionuclides in di-valent and/or multi-valent cations are favorably adsorbed by magnesium oxide; but not for the those in mono-valent cations. In addition, the adsorption by magnesium oxide was not effective to most of the radionuclides in negative ionic species. From the observations, the adsorption mechanism is more prominently by the ion exchange of the di- or multi-valent cation species with the hydrous magnesium oxide. Separation of the radionuclides related to the corrosion products possibly produced in a nuclear power plant from natural seawater was attempted by the magnesium oxide adsorption method. It should be emphasized that the adsorption method was found to be practical for separating radionuclides from a large quantity of natural seawater with high recovery and high reproducibility. (author)

[SIGNIFICANCE OF MAGNESIUM IN PHISIOLOGY AND PATHOLOGY OF THE DIGESTIVE SYSTEM].

Science.gov (United States)

Grigus, Ya I; Mikhaylova, O D; Gorbunov A Yu; Vakhrushev, Ya M

2015-01-01

The article describes the physiological role of magnesium in the human body and its importance for metabolic processes. The reasons for the development of magnesium deficiency and hypermagnesaemia and its clinical symptoms are shown. The specialties of magnesium metabolism disturbances in gastroenterological pathology are described. Particular attention paid to the correction of magnesium levels with deviations of its content in the organism.

The prospects of biodegradable magnesium-based alloys in osteosynthesis

Directory of Open Access Journals (Sweden)

V. N. Chorny

2013-12-01

Full Text Available In the analytical review of the literature the main stages of development of biodegradable magnesium alloys in surgery and traumatology were discussed. The analysis revealed the main problems: there is no way to control the speed of the biological resorption alloys, the effects of products of magnesium degradation on the tissues and the organism in general are not studied, there is no information on the characteristics of the regeneration of bone tissue when implanted magnesium implanted magnesium alloys Materials for osteosynthesis with metal clamps made of steel X18H9T are used in 25,0-52,2% of cases, the corrosion of fasteners reaches 18-21%. Corrosion of the metal clips leads to the increase of the concentration of iron, chromium, nickel and titanium in the surrounding tissue. Electrochemical processes in metallic implants occurs due to their structural and chemical inhomogeneous. The microstructure of stainless steel is presented by differently oriented grains. Therefore, the question remains relevant to finding biodegradable materials suitable for implants for osteosynthesis, which could be completely metabolized by the organism, without causing of the pathological effects on the surrounding tissue and the body. The property of magnesium metal dissolved in the tissues of a living organism is known since the 19th century. Payr suggested the use of magnesium metal needles for the treatment of angiomas, in order to achieve thrombosis surrounding the tumor. In 1937 Lambotte made a post in the French Surgical Academy on the application of the osteosynthesis of the shin bone clamps with alloy Dow-metal (magnesium - 92% Aluminum - 8% + traces of manganese, made in the form of loops and screws. In 1938, Earl D. Mc.Braid and published their positive experience with plates and screws made of material similar in composition to the Dow-metal for osteosynthesis of fractures of the arm and forearm bones. Magnesium alloys may be used as a material for

Relationship of serum magnesium level and supplemental magnesium dosage with post coronary artery bypass graft surgery arrhythmias

Directory of Open Access Journals (Sweden)

Najafi M

2007-06-01

Full Text Available Background: Atrial and ventricular arrhythmias are among the most common complications after coronary artery bypass graft (CABG surgery. Previous studies demonstrated that cardiopulmonary bypass itself results in reduced serum magnesium levels. In this study, we evaluated the effect of total blood magnesium level (TMG on the prevention of perioperative arrhythmias with routine regimens of 2-4 grams supplemental magnesium (SMG. Methods: TMG was measured in patients who were scheduled for CABG on three occasions: just before anesthesia, just after entering the intensive care unit (ICU after completion of the sugery, and on the first morning after the operation. Patients were evaluated for primary cardiac rhythm and other variables that could have an influence on the magnesium level, including serum creatinine, urine output in the operating room and diuretic therapy. The SMG dosage was also recorded in the operating room and ICU. Patients were then evaluated for the rate and type of arrhythmia for the next three days. Results: The mean TMG levels in 174 cases were 2.2 (0.5, 2.6 (0.6 and 2.4 (0.6 mg/dl for the three occasions, respectively. The mean SMG was 2.5 (1.2 grams. Of 164 patients, 51 (31% developed the following post-operative arrhythmias: AF (7.3%, non-AF SVA (15.2% and ventricular (16.5%. The mean serum creatinine level and urine output were 1.2 mg/dl and 1800 ml, respectively. Although there was a significant difference between the TMG levels on the three different occasions (P<0.001, all values were within normal range. When we stratified the TMG levels of the patients based on administered SMG, the Mentel-Haenszel test revealed no significant difference between the first and third TMG (P=0.6. Although the TMG levels were higher in arrhythmic patients compared to those without arrhythmia (2.25 vs. 2.14 mg/dl, both values were within the normal range and there was no significant difference between the two groups. Serum creatinine levels

Thermionic vacuum arc (TVA) technique for magnesium thin film deposition

Energy Technology Data Exchange (ETDEWEB)

Balbag, M.Z., E-mail: zbalbag@ogu.edu.t [Eskisehir Osmangazi University, Education Faculty, Primary Education, Meselik Campus, Eskisehir 26480 (Turkey); Pat, S.; Ozkan, M.; Ekem, N. [Eskisehir Osmangazi University, Art and Science Faculty, Physics Department, Eskisehir 26480 (Turkey); Musa, G. [Ovidius University, Physics Department, Constanta (Romania)

2010-08-15

In this study, magnesium thin films were deposited on glass substrate by the Thermionic Vacuum Arc (TVA) technique for the first time. We present a different technique for deposition of high-quality magnesium thin films. By means of this technique, the production of films is achieved by condensing the plasma of anode material generated using Thermionic Vacuum Arc (TVA) under high vacuum conditions onto the surface to be coated. The crystal orientation and morphology of the deposited films were investigated by using XRD, EDX, SEM and AFM. The aim of this study is to search the use of TVA technique to coat magnesium thin films and to determine some of the physical properties of the films generated. Furthermore, this study will contribute to the scientific studies which search the thin films of magnesium or the compounds containing magnesium. In future, this study will be preliminary work to entirely produce magnesium diboride (MgB{sub 2}) superconductor thin film with the TVA technique.

Corrosion mechanism of model zinc-magnesium alloys in atmospheric conditions

International Nuclear Information System (INIS)

Prosek, T.; Nazarov, A.; Bexell, U.; Thierry, D.; Serak, J.

2008-01-01

Recently, superior corrosion properties of zinc coatings alloyed with magnesium have been reported. Corrosion behaviour of model zinc-magnesium alloys was studied to understand better the protective mechanism of magnesium in zinc. Alloys containing from 1 to 32 wt.% magnesium, pure zinc, and pure magnesium were contaminated with sodium chloride and exposed to humid air for 28 days. Composition of corrosion products was analyzed using infrared spectroscopy (FTIR), ion chromatography (IC), and Auger electron spectroscopy (AES). The exposure tests were completed with scanning Kelvin probe (SKP) and electrochemical measurements. Weight loss of ZnMg alloys with 1-16 wt.% magnesium was lower than that of pure zinc. Up to 10-fold drop in weight loss was found for materials with 4-8 wt.% Mg in the structure. The improved corrosion stability of ZnMg alloys was connected to the presence of an Mg-based film adjacent to the metal surface. It ensured stable passivity in chloride environment and limited the efficiency of oxygen reduction

Nuclear reactor shield including magnesium oxide

International Nuclear Information System (INIS)

Rouse, C.A.; Simnad, M.T.

1981-01-01

An improvement is described for nuclear reactor shielding of a type used in reactor applications involving significant amounts of fast neutron flux. The reactor shielding includes means providing structural support, neutron moderator material, neutron absorber material and other components, wherein at least a portion of the neutron moderator material is magnesium in the form of magnesium oxide either alone or in combination with other moderator materials such as graphite and iron

On the effect of interaction of molybdenum trioxide and magnesium oxide in water

International Nuclear Information System (INIS)

Bunin, V.M.; Karelin, A.I.; Solov'eva, L.N.

1992-01-01

Interaction of molybdenum trioxide and magnesium oxide in water was studied. It is shown that molybdenum trioxide forms consecutively magnesium molybdate, dimolybdate and magnesium polymolybdates with magnesium oxide

Magnesium and Osteoporosis: Current State of Knowledge and Future Research Directions

Directory of Open Access Journals (Sweden)

Jeanette A. M. Maier

2013-07-01

Full Text Available A tight control of magnesium homeostasis seems to be crucial for bone health. On the basis of experimental and epidemiological studies, both low and high magnesium have harmful effects on the bones. Magnesium deficiency contributes to osteoporosis directly by acting on crystal formation and on bone cells and indirectly by impacting on the secretion and the activity of parathyroid hormone and by promoting low grade inflammation. Less is known about the mechanisms responsible for the mineralization defects observed when magnesium is elevated. Overall, controlling and maintaining magnesium homeostasis represents a helpful intervention to maintain bone integrity.

Special metallurgy - the electrical butt-welding by flashing of sintered magnesium-magnesium oxide composites (1963); Metallurgie speciale - le soudage electrique en bout par etincelage du composite fritte magnesium-magnesie (1963)

Energy Technology Data Exchange (ETDEWEB)

Charleux, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

Electrical resistance welding has become quite important since World War II because of the need of a high yield in aeronautical production. Progress has been due in particular to the improvements made in electronically controlled apparatus making possible the automatic control of welding. For the butt-welding of sections requiring either a high production rate or a high quality weld, the flash butt-welding system has been very much developed these last few years. The use of this welding method is of great importance in the field of the bonding of oxidisable metals such as magnesium or aluminium and its alloys, because the welded joint is free from oxides. This study consists of general considerations on the flash-welding process with regard to temperature distribution in the parts during welding, and to electrical phenomena connected with flashing. Besides this general or theoretical section, we have applied the welding process to the bonding of sintered magnesium, a magnesium-magnesium oxide composite, whose use as a structural element in nuclear reactors is considered. (author) [French] Le soudage electrique par resistance a pris un essor important depuis la derniere guerre mondiale a cause du besoin de haut rendement pour la production aeronautique. Les progres ont ete possibles surtout par l'amelioration des appareils de commande electronique qui permettent un controle automatique de la soudure. Pour le soudage bout a bout de profiles, demandant soit un haut debit de fabrication, soit une haute qualite du joint soude, le procede de soudage en bout par etincelage a ete tres developpe ces dernieres annees. Ce mode de soudage a un domaine d'utilisation important dans la liaison des metaux oxydables tels le magnesium ou l'aluminium et ses alliages, du fait de la proprete du joint soude exempt d'oxydes. Cette etude comporte une consideration generale du processus de l'etincelage, quant a la repartition de la temperature dans les pieces pendant le soudage et aux

Special metallurgy - the electrical butt-welding by flashing of sintered magnesium-magnesium oxide composites (1963); Metallurgie speciale - le soudage electrique en bout par etincelage du composite fritte magnesium-magnesie (1963)

Energy Technology Data Exchange (ETDEWEB)

Charleux, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

Electrical resistance welding has become quite important since World War II because of the need of a high yield in aeronautical production. Progress has been due in particular to the improvements made in electronically controlled apparatus making possible the automatic control of welding. For the butt-welding of sections requiring either a high production rate or a high quality weld, the flash butt-welding system has been very much developed these last few years. The use of this welding method is of great importance in the field of the bonding of oxidisable metals such as magnesium or aluminium and its alloys, because the welded joint is free from oxides. This study consists of general considerations on the flash-welding process with regard to temperature distribution in the parts during welding, and to electrical phenomena connected with flashing. Besides this general or theoretical section, we have applied the welding process to the bonding of sintered magnesium, a magnesium-magnesium oxide composite, whose use as a structural element in nuclear reactors is considered. (author) [French] Le soudage electrique par resistance a pris un essor important depuis la derniere guerre mondiale a cause du besoin de haut rendement pour la production aeronautique. Les progres ont ete possibles surtout par l'amelioration des appareils de commande electronique qui permettent un controle automatique de la soudure. Pour le soudage bout a bout de profiles, demandant soit un haut debit de fabrication, soit une haute qualite du joint soude, le procede de soudage en bout par etincelage a ete tres developpe ces dernieres annees. Ce mode de soudage a un domaine d'utilisation important dans la liaison des metaux oxydables tels le magnesium ou l'aluminium et ses alliages, du fait de la proprete du joint soude exempt d'oxydes. Cette etude comporte une consideration generale du processus de l'etincelage, quant a la repartition de la temperature dans les pieces

Treatment with magnesium sulphate in pre-term birth

DEFF Research Database (Denmark)

Wolf, Hans; Hegaard, H K; Greisen, G

2012-01-01

Premature birth increases a child's risk of cerebral palsy and death. The aim of this work is to investigate the association between treatment with magnesium sulphate during premature deliveries and infants' cerebral palsy and mortality through a meta-analysis of observational studies....... A comprehensive search of the Cochrane Library, EMBASE and the PubMed database from their inceptions to 1 October, 2010 using the keywords 'magnesium sulphate, children/infant/pre-term/premature and cerebral palsy/mortality/morbidity/adverse effects/outcome' identified 11 reports of observational studies. Two...... authors working independently extracted the data. A meta-analysis of the data found an association between magnesium sulphate treatment and a significantly reduced risk of mortality (RR 0.73; 95% CI 0.61-0.89) and cerebral palsy (OR 0.64; 95% CI 0.47-0.89). Antenatal treatment with magnesium sulphate...

Tunable field emission characteristics of ZnO nanowires coated with varied thickness of lanthanum boride thin films

International Nuclear Information System (INIS)

Zhao, C.X.; Li, Y.F.; Chen, Jun; Deng, S.Z.; Xu, N.S.

2013-01-01

Lanthanum boride (LaB x ) thin films with various thicknesses were deposited on ZnO nanowire arrays by electron beam evaporation. Field emission characteristics of ZnO nanowires show close dependence on LaB x coating thickness. The turn-on field increases with increasing LaB x coating thickness from 10 nm to 50 nm. The observed phenomena were explained by a model that the tunneling at ZnO/LaB x interface dominates the emission process. - Highlights: ► Coating thickness dependence of field emission characteristics of ZnO nanowires was observed from LaB x coated ZnO nanowires. ► More stable field emission was observed from ZnO nanowires with LaB x coating. ► A model was proposed that the tunneling at ZnO/LaB x interface dominates the emission process

Characterization of the whiskerlike products formed by hydriding magnesium metal powders

DEFF Research Database (Denmark)

Herley, P. J.; Jones, W.; Vigeholm, Bjørn

1985-01-01

The structure of filamentary crystals produced during the hydriding of magnesium powder has been studies in detail. The needles of small dimensions (typically 0.5 μm in diameter) have been identified by electron analytical techniques to be oriented microcrystals of metallic magnesium. Their forma......The structure of filamentary crystals produced during the hydriding of magnesium powder has been studies in detail. The needles of small dimensions (typically 0.5 μm in diameter) have been identified by electron analytical techniques to be oriented microcrystals of metallic magnesium....... Their formation has been ascribed to the melting of localized aluminum impurities within the bulk magnesium to form a liquid eutectic. In the presence of sublimed magnesium vapor and hydrogen (as a carrier gas) a vapor-liquid-solid mechanism operates to produce a rapid unidirectional extension followed...

Magnesium - distribution and basic metabolism | Olhaberry | South ...

African Journals Online (AJOL)

Magnesium is extensively distributed in soil, water and plants. It is essential for ehzymatic reactions requiring adenosine triphosphate, and the recommended dietary allowance in man is 5 - 10 mg/kg/d. About 50% of magnesium in man is stored in bone, where it is regulated by parathyroid hormone'and 1,25(OH)2-D3.

A Shortened versus Standard Matched Postpartum Magnesium ...

African Journals Online (AJOL)

Magnesium sulphate is currently the most ideal drug for the treatment of eclampsia but its use in Nigeria is still limited due its cost and clinicians inexperience with the drug. The purpose of this study was to determine whether a shortened postpartum course of magnesium sulphate is as effective as the standard Pritchard ...

Magnesium Hydride for Load Levelling Energy Storage

DEFF Research Database (Denmark)

Vigeholm, B.

Some of the magnesium properties essential to the applicability of the reaction Mg+H2⇆MgH2 as a hydrogen storage system have been investigated. Three magnesium powders with particle size smaller than 50 μm average diameter were cycled, over 31, 71 and 151 cycles respectively, at 675K (400°C...

Corrosion Monitoring of PEO-Pretreated Magnesium Alloys

Energy Technology Data Exchange (ETDEWEB)

Gnedenkov, A. S.; Sinebryukhov, S. L.; Mashtalyar, D. V.; Gnedenkov, S. V.; Sergienko, V. I. [Institute of Chemistry, Vladivostok (Russian Federation)

2017-06-15

The MA8 alloy (formula Mg-Mn-Ce) has been shown to have greater corrosion stability than the VMD10 magnesium alloy (formula Mg-Zn-Zr-Y) in chloride-containing solutions by Scanning Vibrating Electrode Technique (SVET) and by optical microscopy, gravimetry, and volumetry. It has been established that the crucial factor for the corrosion activity of these samples is the occurrence of microgalvanic coupling at the sample surface. The peculiarities of the kinetics and mechanism of the corrosion in the local heterogeneous regions of the magnesium alloy surface were investigated by localized electrochemical techniques. The stages of the corrosion process in artificial defects in the coating obtained by plasma electrolytic oxidation (PEO) at the surface of the MA8 magnesium alloy were also studied. The analysis of the experimental data enabled us to determine that the corrosion process in the defect zone develops predominantly at the magnesium/coating interface. Based on the measurements of the corrosion rate of the samples with PEO and composite polymer-containing coatings, the best anticorrosion properties were displayed by the composite polymer-containing coatings.

Effects of oral magnesium supplementation on inflammatory markers in middle-aged overweight women

Directory of Open Access Journals (Sweden)

Nazanin Moslehi

2012-01-01

Full Text Available Background: This study aimed to investigate whether magnesium supplementation might affect serum magnesium, high sensitive C-reactive protein (hs-CRP, plasma fibrinogen, and interleukin 6 (IL-6 levels in healthy middle-aged overweight women. The relationships, if any, between serum magnesium and the inflammatory markers were also examined cross-sectionally in the entire participants at the beginning of the study. Materials and Methods: This double-blinded, placebo-controlled, randomized trial included 74 middle-aged overweight women. Participants were randomly assigned to receive either 250 mg magnesium as magnesium oxide or placebo daily for 8 weeks. Serum magnesium, hs-CRP, fibrinogen and IL-6 concentrations were measured before and after the intervention. Results: Serum magnesium was found to be inversely correlated with hs-CRP (r s =−0.22, P=0.05 in the entire participants at baseline. Serum hs-CRP declined significantly in both groups as compared with baseline values (median change=0.8 mg/L; P Magnesium= 0.03, P Placebo 0.001. Plasma fibrinogen decreased significantly, by 9%, in the magnesium group at the end of week 8 compared to baseline (P=0.001. Mean concentration of IL-6 was significantly increased in the magnesium group comparing the baseline value(P=0.001. However hs-CRP, fibrinogen and IL-6 levels at week 8 or any changes during the study were not statistically different between the two groups. Serum magnesium showed no significant changes in any groups. Conclusions: Serum magnesium had a significant inverse correlation with hs-CRP. In the present study, magnesium as magnesium oxide, 250 mg/day, for 8 weeks did not significantly attenuate inflammatory markers in the magnesium group as compared to the placebo.

Magnesium silicide production and silane synthesis on its basis

International Nuclear Information System (INIS)

Taurbaev, T.I.; Mukashev, F.A.; Manakov, S.M.; Francev, U.V.; Kalblanbekov, B.M.; Akhter, P.; Abbas, M.; Hussain, A.

2003-01-01

We had developed an alternative method of production of magnesium silicide with use of ferroalloys of silicon. Magnesium silicide is raw material for silane synthesis. The essence of the method consist of sintering FS -75 (ferrosilicium with 75 % of silicon and 25 % of iron, made by ferroalloy factories) with metal magnesium at temperature of 650 deg. C. The X-ray analysis has shown formation of magnesium silicide. That is further used for synthesis of silane. The output of silane is 60 % in respect of the contents of silicon. After removing the water vapors the mass-spectrometer analysis has estimated the purity of silane as 99.95 % with no detection of phosphine and diborane. (author)

Polyanthraquinone-Based Organic Cathode for High-Performance Rechargeable Magnesium-Ion Batteries

Energy Technology Data Exchange (ETDEWEB)

Pan, Baofei [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Huang, Jinhua [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Feng, Zhenxing [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Zeng, Li [Applied Physics Program, Department of Materials Science and Engineering and Department of Physics and Astronomy, Northwestern University, Evanston IL 60208 USA; He, Meinan [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Zhang, Lu [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Vaughey, John T. [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Bedzyk, Michael J. [Applied Physics Program, Department of Materials Science and Engineering and Department of Physics and Astronomy, Northwestern University, Evanston IL 60208 USA; Fenter, Paul [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Zhang, Zhengcheng [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Burrell, Anthony K. [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Liao, Chen [Joint Center for Energy Storage Research, Chemical Science and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA

2016-05-09

Two anthraquinone-based polymers aiming at improving the capacity and voltage of magnesium ion batteries, were synthesized and characterized. The excellent battery cycling performance was demonstrated with the electrolyte consisting of magnesium bis(hexamethyldisilazide) and magnesium chloride.

Magnesium and uranium ignition in different gaseous atmospheres; Inflammabilite du magnesium et de l'uranium dans l'air et le gaz carbonique

Energy Technology Data Exchange (ETDEWEB)

Darras, R; Baque, P; Leclercq, D [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

Magnesium, uranium and some of their alloys burning temperatures have been systematically determined in an air or carbon dioxide atmosphere, either dry or wet. Two different ways of heating have been used: either continuously rising up the temperature, or heating to and then maintaining a constant temperature. The results are clearly different in the two cases. Besides, if moisture has little effect on the magnesium burning temperatures in air, it does lower them by about 130-140 deg. C in CO{sub 2}. The differences of sight between the burning of magnesium and uranium have been noticed; this leads to distinguish between an 'ignition' and an 'inflammation'. (author) [French] Les temperatures auxquelles apparait la combustion vive du magnesium, de l'uranium et certains de leurs alliages ont ete determinees systematiquement dans l'air et le gaz carbonique, soit secs, soit humidifies. On a mis en evidence l'influence du mode de chauffage sur les resultats: soit montee en temperature continue, soit stabilisation a partir d'une certaine temperature. En outre, si la presence d'humidite affecte peu les temperatures de combustion vive du magnesium dans l'air, elle les abaisse de 130 a 140 deg. C dans le gaz carbonique. Les differences d'aspect entre la combustion vive du magnesium et de l'uranium ont egalement ete remarquees, ce qui amene notamment a distinguer une 'ignition' d'une 'inflammation'. (auteur)

Magnesium Hall Thruster

Science.gov (United States)

Szabo, James J.

2015-01-01

This Phase II project is developing a magnesium (Mg) Hall effect thruster system that would open the door for in situ resource utilization (ISRU)-based solar system exploration. Magnesium is light and easy to ionize. For a Mars- Earth transfer, the propellant mass savings with respect to a xenon Hall effect thruster (HET) system are enormous. Magnesium also can be combusted in a rocket with carbon dioxide (CO2) or water (H2O), enabling a multimode propulsion system with propellant sharing and ISRU. In the near term, CO2 and H2O would be collected in situ on Mars or the moon. In the far term, Mg itself would be collected from Martian and lunar regolith. In Phase I, an integrated, medium-power (1- to 3-kW) Mg HET system was developed and tested. Controlled, steady operation at constant voltage and power was demonstrated. Preliminary measurements indicate a specific impulse (Isp) greater than 4,000 s was achieved at a discharge potential of 400 V. The feasibility of delivering fluidized Mg powder to a medium- or high-power thruster also was demonstrated. Phase II of the project evaluated the performance of an integrated, highpower Mg Hall thruster system in a relevant space environment. Researchers improved the medium power thruster system and characterized it in detail. Researchers also designed and built a high-power (8- to 20-kW) Mg HET. A fluidized powder feed system supporting the high-power thruster was built and delivered to Busek Company, Inc.

Extraction of magnesium from calcined dolomite ore using hydrochloric acid leaching

Science.gov (United States)

Royani, Ahmad; Sulistiyono, Eko; Prasetiyo, Agus Budi; Subagja, Rudi

2018-05-01

Magnesium is widely used in varieties industrial sector. Dolomite is one source of magnesium besides seawater. The extraction of magnesium from dolomite ores can be done by leaching process. In this work, the dolomite leaching to extract magnesium by hydrochloric acid was investigated. The leaching experiments were performed in a spherical glass batch reactor having a capacity of 1000 ml. The effects of the stirring speed, acid concentration, reaction temperature and liquid-solid ratio for each reaction time of 1; 2; and 3 h on the Mg leaching have been evaluated. 5 ml of solution sample were collected from the leached solutions, then it was filtered prior to analysis by ICP OES. The experimental results show that the magnesium extraction increases along with the increase of acid concentration, liquid-solid ratio and temperature. The optimum conditions for magnesium extraction were achieved at temperature 75 °C, extraction time 3 h, the HCl concentration of 2 M, the liquid-solid ratio 20 ml/g and stirring speed of 400 rpm. At this condition 98, 82 % of magnesium were extracted from dolomite. The conclusion obtained from this leaching process is that the magnesium can be extracted from dolomite by using hydrochloric acid solutions.

Evaluation of magnesium ions release, biocorrosion, and hemocompatibility of MAO/PLLA-modified magnesium alloy WE42.

Science.gov (United States)

Lu, Ping; Cao, Lu; Liu, Yin; Xu, Xinhua; Wu, Xiangfeng

2011-01-01

Magnesium alloys may potentially be applied as biodegradable metallic materials in cardiovascular stent. However, the high corrosion rate hinders its clinical application. In this study, a new approach was adopted to control the corrosion rate by fabricating a biocompatible micro-arc oxidation/poly-L-lactic acid (MAO/PLLA) composite coating on the magnesium alloy WE42 substrate and the biocompatibility of the modified samples was investigated. The scanning electronic microscope (SEM) images were used to demonstrate the morphology of the samples before and after being submerged in hanks solution for 4 weeks. The degradation was evaluated through the magnesium ions release rate and electrochemical impedance spectroscopy (EIS) test. The biocompatibility of the samples was demonstrated by coagulation time and hemolysis behavior. The result shows that the poly-L-lactic acid (PLLA) effectively improved the corrosion resistance by sealing the microcracks and microholes on the surface of the MAO coating. The modified samples had good compatibility. © 2010 Wiley Periodicals, Inc.

The High Strain Rate Deformation Behavior of High Purity Magnesium and AZ31B Magnesium Alloy

Science.gov (United States)

Livescu, Veronica; Cady, Carl M.; Cerreta, Ellen K.; Henrie, Benjamin L.; Gray, George T.

The deformation in compression of pure magnesium and AZ31B magnesium alloy, both with a strong basal pole texture, has been investigated as a function of temperature, strain rate, and specimen orientation. The mechanical response of both metals is highly dependent upon the orientation of loading direction with respect to the basal pole. Specimens compressed along the basal pole direction have a high sensitivity to strain rate and temperature and display a concave down work hardening behavior. Specimens loaded perpendicularly to the basal pole have a yield stress that is relatively insensitive to strain rate and temperature and a work hardening behavior that is parabolic and then linearly upwards. Both specimen orientations display a mechanical response that is sensitive to temperature and strain rate. Post mortem characterization of the pure magnesium was conducted on a subset of specimens to determine the microstructural and textural evolution during deformation and these results are correlated with the observed work hardening behavior and strain rate sensitivities were calculated.

Sol – Gel synthesis and characterization of magnesium peroxide nanoparticles

International Nuclear Information System (INIS)

Jaison, J; Chan, Y S; Ashok raja, C; Balakumar, S

2015-01-01

Magnesium peroxide is an excellent source of oxygen in agriculture applications, for instance it is used in waste management as a material for soil bioremediation to remove contaminants from polluted underground water, biological wastes treatment to break down hydrocarbon, etc. In the present study, sol-gel synthesis of magnesium peroxide (MgO 2 ) nanoparticles is reported. Magnesium peroxide is odourless; fine peroxide which releases oxygen when reacts with water. During the sol-gel synthesis, the magnesium malonate intermediate is formed which was then calcinated to obtain MgO 2 nanoparticles. The synthesized nanoparticles were characterized using Thermo gravimetric -Differential Thermal Analysis (TG- DTA), X-Ray Diffraction studies (XRD) and High Resolution Transmission Electron Microscope (HRTEM). Our study provides a clear insight that the formation of magnesium malonate during the synthesis was due to the reaction between magnesium acetate, oxalic acid and ethanol. In our study, we can conclude that the calcination temperature has a strong influence on particle size, morphology, monodispersity and the chemistry of the particles. (paper)

Effective and Environmentally Friendly Nickel Coating on the Magnesium Alloy

Directory of Open Access Journals (Sweden)

Ivana Škugor Rončević

2016-12-01

Full Text Available The low density and good mechanical properties make magnesium and its alloys attractive construction materials in the electronics, automotive, and aerospace industry, together with application in medicine due to their biocompatibility. Magnesium AZ91D alloy is an alloy with a high content of aluminum, whose mechanical properties overshadow the low corrosion resistance caused by the composition of the alloy and the existence of two phases: α magnesium matrix and β magnesium aluminum intermetallic compound. To improve the corrosion resistance, it is necessary to find an effective protection method for the alloy surface. Knowing and predicting electrochemical processes is an essential for the design and optimization of protective coatings on magnesium and its alloys. In this work, the formations of nickel protective coatings on the magnesium AZ91D alloy surface by electrodeposition and chemical deposition, are presented. For this purpose, environmentally friendly electrolytes were used. The corrosion resistance of the protected alloy was determined in chloride medium using appropriate electrochemical techniques. Characterization of the surface was performed with highly sophisticated surface-analytical methods.

Magnesium, hemostasis, and outcomes in patients with intracerebral hemorrhage.

Science.gov (United States)

Liotta, Eric M; Prabhakaran, Shyam; Sangha, Rajbeer S; Bush, Robin A; Long, Alan E; Trevick, Stephen A; Potts, Matthew B; Jahromi, Babak S; Kim, Minjee; Manno, Edward M; Sorond, Farzaneh A; Naidech, Andrew M; Maas, Matthew B

2017-08-22

We tested the hypothesis that admission serum magnesium levels are associated with hematoma volume, hematoma growth, and functional outcomes in patients with intracerebral hemorrhage (ICH). Patients presenting with spontaneous ICH were enrolled in an observational cohort study that prospectively collected demographic, clinical, laboratory, radiographic, and outcome data. We performed univariate and adjusted multivariate analyses to assess for associations between serum magnesium levels and initial hematoma volume, final hematoma volume, and in-hospital hematoma growth as radiographic measures of hemostasis, and functional outcome measured by the modified Rankin Scale (mRS) at 3 months. We included 290 patients for analysis. Admission serum magnesium was 2.0 ± 0.3 mg/dL. Lower admission magnesium levels were associated with larger initial hematoma volumes on univariate ( p = 0.02), parsimoniously adjusted ( p = 0.002), and fully adjusted models ( p = 0.006), as well as greater hematoma growth ( p = 0.004, p = 0.005, and p = 0.008, respectively) and larger final hematoma volumes ( p = 0.02, p = 0.001, and p = 0.002, respectively). Lower admission magnesium level was associated with worse functional outcomes at 3 months (i.e., higher mRS; odds ratio 0.14, 95% confidence interval 0.03-0.64, p = 0.011) after adjustment for age, admission Glasgow Coma Scale score, initial hematoma volume, time from symptom onset to initial CT, and hematoma growth, with evidence that the effect of magnesium is mediated through hematoma growth. These data support the hypothesis that magnesium exerts a clinically meaningful influence on hemostasis in patients with ICH. © 2017 American Academy of Neurology.

Dielectric behaviour of sodium and potassium doped magnesium ...

Indian Academy of Sciences (India)

Dielectric behaviour of sodium and potassium doped magnesium titanate. VISHNU SHANKER. ∗. , SANTOSH KUMAR and T SURENDAR. Department of Chemistry, National Institute of Technology, Warangal 506 004, India. MS received 10 November 2011; revised 27 February 2012. Abstract. Pure phase of magnesium ...

Post traumatic tetanus and role magnesium sulphate

International Nuclear Information System (INIS)

Sikendr, R.I.; Samad, B.U.; Memon, M.I.

2009-01-01

Tetanus is a life threatening disease. Reported mortality for tetanus is 15-39%. Conventional treatment includes heavy sedation and artificial ventilation. Complications resulting from long term heavy sedation and artificial ventilation contribute to 60% of the total mortality caused by tetanus. In this study magnesium sulphate was used to reduce the need for sedation and artificial ventilation. Objectives of this prospective study were to determine the role of magnesium sulphate in post traumatic tetanus. The study was carried out in surgical Intensive Care at Pakistan Institute of Medical Sciences (PIMS), Islamabad from Jan 2004 to Dec 2007. Forty-four patients presented during this period and 33 patients were included in the study. All patients had tracheostomy done within 48 hours. Every patient was started Magnesium Sulphate therapy for control of spasms after sending baseline investigations. Patients were given ventilatory support when needed. All data was entered in well structured proforma. SPSS-10 was used to analyse data. Thirty-three patients were included in the study and all patients were given magnesium sulphate. Out of these, 45.5% cases were grade 4 tetanus, 73.6% and 63.3% cases did not require artificial ventilation and additional sedation respectively, 51.1% patients remained free of complications of tetanus. Overall mortality was 30.3%. Use of Magnesium Sulphate is safe and reduces the need for sedation and artificial ventilation in high grade tetanus thus contributing to survival benefit in adult post-traumatic tetanus cases. (author)

Comparison of Selective Laser Melted Titanium and Magnesium Implants Coated with PCL

Science.gov (United States)

Matena, Julia; Petersen, Svea; Gieseke, Matthias; Teske, Michael; Beyerbach, Martin; Kampmann, Andreas; Escobar, Hugo Murua; Gellrich, Nils-Claudius; Haferkamp, Heinz; Nolte, Ingo

2015-01-01

Degradable implant material for bone remodeling that corresponds to the physiological stability of bone has still not been developed. Promising degradable materials with good mechanical properties are magnesium and magnesium alloys. However, excessive gas production due to corrosion can lower the biocompatibility. In the present study we used the polymer coating polycaprolactone (PCL), intended to lower the corrosion rate of magnesium. Additionally, improvement of implant geometry can increase bone remodeling. Porous structures are known to support vessel ingrowth and thus increase osseointegration. With the selective laser melting (SLM) process, defined open porous structures can be created. Recently, highly reactive magnesium has also been processed by SLM. We performed studies with a flat magnesium layer and with porous magnesium implants coated with polymers. The SLM produced magnesium was compared with the titanium alloy TiAl6V4, as titanium is already established for the SLM-process. For testing the biocompatibility, we used primary murine osteoblasts. Results showed a reduced corrosion rate and good biocompatibility of the SLM produced magnesium with PCL coating. PMID:26068455

Study of near-critical states of liquid-vapor phase transition of magnesium

International Nuclear Information System (INIS)

Emelyanov, A N; Shakhray, D V; Golyshev, A A

2015-01-01

Study of thermodynamic parameters of magnesium in the near-critical point region of the liquid-vapor phase transition and in the region of metal-nonmetal transition was carried out. Measurements of the electrical resistance of magnesium after shock compression and expansion into gas (helium) environment in the process of isobaric heating was carried out. Heating of the magnesium surface by heat transfer with hot helium was performed. The registered electrical resistance of expanded magnesium was about 10 4 -10 5 times lower than the electrical resistance of the magnesium under normal condition at the density less than the density of the critical point. Thus, metal-nonmetal transition was found in magnesium. (paper)

Increases in Intravenous Magnesium Use among Hospitalized Patients: An Institution Cross-Sectional Experience

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Bryce A. Kiberd

2015-06-01

Full Text Available Background: Among hospitalized patients, indications for the measurement of magnesium levels and treatment of hypomagnesemia with intravenous magnesium are not well defined. Recently, there have been reports of worldwide shortages of intravenous magnesium sulphate. Objective: To examine secular trends in the administration of intravenous magnesium on hospital wards at a tertiary care institution. The secondary objective is to identify factors associated with magnesium use among admitted patients. Methods: Retrospective cross-section review of hospitalized patients at a single Canadian tertiary care center. Utilization of non-parental nutrition intravenous magnesium from 2003 to 2013 stratified by hospital ward was examined. In addition, patient level data from select wards (including medical and surgical services was examined at early and more recent time period (4/2006 versus 4/2013. Results: Among the 248,329 hospitalized patients, intravenous magnesium use increased by 2.86 fold from 2003 to 2013. Not all wards had an increase whereas some had nearly a 10 fold increase in use. In the sample ( n = 769, (adjusting for admission magnesium level, presence of an indication for intravenous magnesium, ward location, comorbidity and demographics intravenous magnesium administration was higher (25.8 % versus 5.5 % in 2013 versus 2006 (OR 13.91 (95 % CI, 6.21–31.17, p < 0.001. Despite this increase in intravenous magnesium administration, <3 % of patients were admitted on oral magnesium in 2006 and 2013. For patients receiving intravenous magnesium only a minority were discharged on oral therapy despite low levels. Conclusions: This center has witnessed a considerable increase in the use of in-hospital intravenous magnesium over the last 6 years that cannot be explained for by medical indications. The risks and benefits of this therapy deserve further study. If this change in practice is representative of other North American hospitals, it may be

Corrosion of pure magnesium under thin electrolyte layers

International Nuclear Information System (INIS)

Zhang Tao; Chen Chongmu; Shao Yawei; Meng Guozhe; Wang Fuhui; Li Xiaogang; Dong Chaofang

2008-01-01

The corrosion behavior of pure magnesium was investigated by means of cathodic polarization curve, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) under aerated and deaerated thin electrolyte layers (TEL) with various thicknesses. Based on shot noise theory and stochastic theory, the EN results were quantitatively analyzed by using the Weibull and Gumbel distribution function, respectively. The results show that the cathodic process of pure magnesium under thin electrolyte layer was dominated by hydrogen reduction. With the decreasing of thin electrolyte layer thickness, cathodic process was retarded slightly while the anodic process was inhibited significantly, which indicated that both the cathodic and anodic process were inhibited in the presence of oxygen. The absence of oxygen decreased the corrosion resistance of pure magnesium in case of thin electrolyte layer. The corrosion was more localized under thin electrolyte layer than that in bulk solution. The results also demonstrate that there exist two kinds of effects for thin electrolyte layer on the corrosion behavior of pure magnesium: (1) the rate of pit initiation was evidently retarded compared to that in bulk solution; (2) the probability of pit growth oppositely increased. The corrosion model of pure magnesium under thin electrolyte layer was suggested in the paper

Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts; Apport des isotopes stables a l'etude de la pharmacocinetique de sels de magnesium

Energy Technology Data Exchange (ETDEWEB)

Benech, H

1999-05-28

The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, {sup 25}Mg and {sup 26}Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

Friction welding of AZ31 magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Tsujino, R.; Ochi, H. [Osaka Inst. of Tech., Osaka (Japan); Kawai, G. [Osaka Sangyo Univ., Osaka (Japan); Yamaguchi, H.; Ogawa, K. [Osaka Prefecture Univ., Osaka (Japan); Suga, Y. [Keio Univ., Kanagawa (Japan)

2003-07-01

In this paper, for an acceleration of utilization of magnesium alloy which is being interested in recent years, friction welding of AZ31 magnesium alloy was carried out, and the joint performance was discussed in relation to the deformation heat input in the upset stage and upset loss as a evaluation factor. Where, the deformation heat input in the upset stage is mechanical work represented by the product of upset speed and axial pressure. As a result, it was made clear that the friction welding of AZ31 magnesium alloy was easy in the atmosphere, and good welded joints without a non- adhesion area at the weld interface could de obtained. Moreover, the evaluation factors discussed were possible to evaluate to joint performance. (orig.)

Corrosion of magnesium and aluminum in palm biodiesel: A comparative evaluation

International Nuclear Information System (INIS)

Chew, K.V.; Haseeb, A.S.M.A.; Masjuki, H.H.; Fazal, M.A.; Gupta, M.

2013-01-01

The present study aims to investigate the comparative corrosion of light-weight metals such as aluminum and magnesium in palm biodiesel. Immersion test at room temperature was carried out for each metal for 1440 h. Sample characterization techniques employed include weight loss measurement, SEM (scanning electron microscope), XRD (X-ray diffraction), TAN (total acid number) and FTIR (Fourier transform infrared spectroscopy). Results showed that the corrosion rate of magnesium was much higher compared to that of aluminum. The surface morphology revealed a significant difference between the biodiesel exposed aluminum and magnesium specimens. Upon exposure to biodiesel, the magnesium surface was found to be fully covered by gel-like sticky mass while the aluminum surface remained clean. - Highlights: • Biodiesel is highly corrosive for magnesium. • Biodiesel exposed magnesium surface showed yellowish gel-like sticky mass. • Biodiesel undergoes significant degradation upon exposure to metals

Precipitation and Hardening in Magnesium Alloys

Science.gov (United States)

Nie, Jian-Feng

2012-11-01

Magnesium alloys have received an increasing interest in the past 12 years for potential applications in the automotive, aircraft, aerospace, and electronic industries. Many of these alloys are strong because of solid-state precipitates that are produced by an age-hardening process. Although some strength improvements of existing magnesium alloys have been made and some novel alloys with improved strength have been developed, the strength level that has been achieved so far is still substantially lower than that obtained in counterpart aluminum alloys. Further improvements in the alloy strength require a better understanding of the structure, morphology, orientation of precipitates, effects of precipitate morphology, and orientation on the strengthening and microstructural factors that are important in controlling the nucleation and growth of these precipitates. In this review, precipitation in most precipitation-hardenable magnesium alloys is reviewed, and its relationship with strengthening is examined. It is demonstrated that the precipitation phenomena in these alloys, especially in the very early stage of the precipitation process, are still far from being well understood, and many fundamental issues remain unsolved even after some extensive and concerted efforts made in the past 12 years. The challenges associated with precipitation hardening and age hardening are identified and discussed, and guidelines are outlined for the rational design and development of higher strength, and ultimately ultrahigh strength, magnesium alloys via precipitation hardening.

Some Structural Properties of the Mixed Lead-Magnesium Hydroxyapatites

Science.gov (United States)

Kaaroud, K.; Ben Moussa, S.; Brigui, N.; Badraoui, B.

2018-02-01

Lead-magnesium hydroxyapatite solid solutions Pb(10- x)Mg x (PO4)6(OH)2 have been prepared via a hydrothermal process. They were characterized by X-ray powder diffraction, Transmission Electron Microscopy (TEM), chemical and IR spectroscopic analyses. The results of the structural refinement indicated that the limits of lead-magnesium solid solutions ( x ≤ 1.5), a regular decrease of the lattice constant a and a preferential magnesium distribution in site S(I). Through the progressive replacement of Pb2+ ( r = 0.133 nm) by the smaller cation Mg2+ ( r = 0.072 nm), all interatomic distances decrease in accordance with the decrease of the cell parameters. According to what could be expected from the coordinance of the metallic sites S(I) (hexacoordination) and S(II) (heptacoordination), the small magnesium cation preferentially occupies the four sites S(I). The results of the TEM analysis confirm the presence of magnesium in the starting solution and reveals the decrease in the average size of crystals. The IR spectra show the presence of the absorption bands characteristic for the apatite structure.

Extracellular Calcium and Magnesium in Preeclampsia and Eclampsia

African Journals Online (AJOL)

The cause of preeclampsia remains unknown and calcium and magnesium supplement are being suggested as means of prevention. The objective of this study was to assess magnesium and calcium in the plasma and cerebrospinal fluid of Nigerian women with preeclampsia and eclampsia. Setting was University of ...

Serum magnesium is associated with the risk of dementia.

Science.gov (United States)

Kieboom, Brenda C T; Licher, Silvan; Wolters, Frank J; Ikram, M Kamran; Hoorn, Ewout J; Zietse, Robert; Stricker, Bruno H; Ikram, M Arfan

2017-10-17

To determine if serum magnesium levels are associated with the risk of all-cause dementia and Alzheimer disease. Within the prospective population-based Rotterdam Study, we measured serum magnesium levels in 9,569 participants, free from dementia at baseline (1997-2008). Participants were subsequently followed up for incident dementia, determined according to the DSM-III-R criteria, until January 1, 2015. We used Cox proportional hazard regression models to associate quintiles of serum magnesium with incident all-cause dementia. We used the third quintile as a reference group and adjusted for age, sex, Rotterdam Study cohort, educational level, cardiovascular risk factors, kidney function, comorbidities, other electrolytes, and diuretic use. Our study population had a mean age of 64.9 years and 56.6% were women. During a median follow-up of 7.8 years, 823 participants were diagnosed with all-cause dementia. Both low serum magnesium levels (≤0.79 mmol/L) and high serum magnesium levels (≥0.90 mmol/L) were associated with an increased risk of dementia (hazard ratio [HR] 1.32, 95% confidence interval [CI] 1.02-1.69, and HR 1.30, 95% CI 1.02-1.67, respectively). Both low and high serum magnesium levels are associated with an increased risk of all-cause dementia. Our results warrant replication in other population-based studies. © 2017 American Academy of Neurology.

Magnesium protects cognitive functions and synaptic plasticity in streptozotocin-induced sporadic Alzheimer's model.

Directory of Open Access Journals (Sweden)

Zhi-Peng Xu

Full Text Available Alzheimer's disease (AD is characterized by profound synapse loss and impairments of learning and memory. Magnesium affects many biochemical mechanisms that are vital for neuronal properties and synaptic plasticity. Recent studies have demonstrated that the serum and brain magnesium levels are decreased in AD patients; however, the exact role of magnesium in AD pathogenesis remains unclear. Here, we found that the intraperitoneal administration of magnesium sulfate increased the brain magnesium levels and protected learning and memory capacities in streptozotocin-induced sporadic AD model rats. We also found that magnesium sulfate reversed impairments in long-term potentiation (LTP, dendritic abnormalities, and the impaired recruitment of synaptic proteins. Magnesium sulfate treatment also decreased tau hyperphosphorylation by increasing the inhibitory phosphorylation of GSK-3β at serine 9, thereby increasing the activity of Akt at Ser473 and PI3K at Tyr458/199, and improving insulin sensitivity. We conclude that magnesium treatment protects cognitive function and synaptic plasticity by inhibiting GSK-3β in sporadic AD model rats, which suggests a potential role for magnesium in AD therapy.

Preparation of magnesium metal matrix composites by powder metallurgy process

Science.gov (United States)

Satish, J.; Satish, K. G., Dr.

2018-02-01

Magnesium is the lightest metal used as the source for constructional alloys. Today Magnesium based metal matrix composites are widely used in aerospace, structural, oceanic and automobile applications for its light weight, low density(two thirds that of aluminium), good high temperature mechanical properties and good to excellent corrosion resistance. The reason of designing metal matrix composite is to put in the attractive attributes of metals and ceramics to the base metal. In this study magnesium metal matrix hybrid composite are developed by reinforcing pure magnesium with silicon carbide (SiC) and aluminium oxide by method of powder metallurgy. This method is less expensive and very efficient. The Hardness test was performed on the specimens prepared by powder metallurgy method. The results revealed that the micro hardness of composites was increased with the addition of silicon carbide and alumina particles in magnesium metal matrix composites.

Blood triggered corrosion of magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Geis-Gerstorfer, J., E-mail: juergen.geis-gerstorfer@uni-tuebingen.de [Section Medical Materials and Technology, University Hospital Tuebingen, Tuebingen (Germany); Schille, Ch.; Schweizer, E.; Rupp, F.; Scheideler, L. [Section Medical Materials and Technology, University Hospital Tuebingen, Tuebingen (Germany); Reichel, H.-P. [Weisensee Company, Eichenzell (Germany); Hort, N. [GKSS Research Center, Institute of Materials Research, Geesthacht (Germany); Nolte, A.; Wendel, H.-P. [Div. Congenital and Paediatric Cardiac Surgery, University Children' s Hospital, Tuebingen (Germany)

2011-12-15

Intravascular stents manufactured out of bioabsorbable magnesium (Mg) or Mg-alloys are considered as auspicious candidates for the next stent generation. However, before clinical application numerous physical and biological tests, especially to predict the clinically highly important degradation kinetics in vivo, have to be performed. In a Chandler-Loop model, the initial degradation of eight different magnesium alloys during 6 h in contact with human whole blood was investigated. The magnesium release varied between 0.91 {+-} 0.33 mg/cm{sup 2} (MgAl9Zn1) and 2.57 {+-} 0.38 mg/cm{sup 2} (MgZn1). No correlation could be found with Mg release data obtained after immersion in simulated body fluid (SBF). This pilot study showed that Mg corrosion is highly influenced by the biological test environment (SBF or blood, etc.) and that a modified Chandler-Loop model with human whole blood may be superior to predict corrosion of Mg alloys under clinical conditions than the SBF models presently used.

Calcium and magnesium silicate hydrates

International Nuclear Information System (INIS)

Lothenbach, B.; L'Hopital, E.; Nied, D.; Achiedo, G.; Dauzeres, A.

2015-01-01

Deep geological disposals are planed to discard long-lived intermediate-level and high-level radioactive wastes. Clay-based geological barriers are expected to limit the ingress of groundwater and to reduce the mobility of radioelements. In the interaction zone between the cement and the clay based material alteration can occur. Magnesium silicate hydrates (M-S-H) have been observed due to the reaction of magnesium sulfate containing groundwater with cements or in the interaction zone between low-pH type cement and clays. M-S-H samples synthesized in the laboratory showed that M-S-H has a variable composition within 0.7 ≤ Mg/Si ≤ 1.5. TEM/EDS analyses show an homogeneous gel with no defined structure. IR and 29 Si NMR data reveal a higher polymerization degree of the silica network in M-S-H compared to calcium silicate hydrates (C-S-H). The presence of mainly Q 3 silicate tetrahedrons in M-S-H indicates a sheet like or a triple-chain silica structure while C-S-H is characterised by single chain-structure. The clear difference in the silica structure and the larger ionic radius of Ca 2+ (1.1 Angstrom) compared to Mg 2+ (0.8 Angstrom) make the formation of an extended solid solution between M-S-H and C-S-H gel improbable. In fact, the analyses of synthetic samples containing both magnesium and calcium in various ratios indicate the formation of separate M-S-H and C-S-H gels with no or very little uptake of magnesium in CS-H or calcium in M-S-H

Research on A3 steel corrosion behavior of basic magnesium sulfate cement

Science.gov (United States)

Xing, Sainan; Wu, Chengyou; Yu, Hongfa; Jiang, Ningshan; Zhang, Wuyu

2017-11-01

In this paper, Tafel polarization technique is used to study the corrosion behavior of A3 steel basic magnesium sulfate, and then analyzing the ratio of raw materials cement, nitrites rust inhibitor and wet-dry cycle of basic magnesium sulfate corrosion of reinforced influence, and the steel corrosion behavior of basic magnesium sulfate compared with magnesium oxychloride cement and Portland cement. The results show that: the higher MgO/MgSO4 mole ratio will reduce the corrosion rate of steel; Too high and too low H2O/MgSO4 mole ratio may speed up the reinforcement corrosion effect; Adding a small amount of nitrite rust and corrosion inhibitor, not only can obviously reduce the alkali type magnesium sulfate in the early hydration of cement steel bar corrosion rate, but also can significantly reduce dry-wet circulation under the action of alkali type magnesium sulfate cement corrosion of reinforcement effect. Basic magnesium sulfate cement has excellent ability to protect reinforced, its long-term corrosion of reinforcement effect and was equal to that of Portland cement. Basic magnesium sulfate corrosion of reinforced is far below the level in the MOC in the case.

Magnesium-made door frame for passenger cars; Pkw-Tuerrahmen aus Magnesium

Energy Technology Data Exchange (ETDEWEB)

Tikal, F.; Vollmer, C. [Kassel Univ. (Gesamthochschule) (Germany). Inst. fuer Produktionstechnik und Logistik

1997-11-01

One of the most complicated parts of a car is the door. An so it will be in the future. More and more parts will be integrated in a car`s door, especially safety and comfort related parts as well as a big number of functional elements. The car industry tries intensively to bring about a growing safety image to its buyers. At the Institute for Technical Production and Logistics (IPL) of the University of Kassel (GhK) a passenger door construction out of magnesium has been developed on the base of a foregoing construction. With the new practice orientated model the time of production could be essentially reduced while at the same time the weight could be decreased. (orig.) [Deutsch] Am Institut fuer Produktionstechnik und Logistik (ipl) der Universitaet Gesamthochschule Kassel wurde ein optimierter Magnesium-Druckguss-Rahmen fuer eine Pkw-Tuer, basierend auf einer vorangegangenen Arbeit, entwickelt. Mit dem neuen praxisnahen Modell konnte die Montagezeit erheblich reduziert und Gewicht eingespart werden. (orig.)

Deformation behaviour of a new magnesium ternary alloy

Science.gov (United States)

Guglielmi, P.; Kaya, A. Arslan; Sorgente, D.; Palumbo, G.

2018-05-01

Magnesium based alloys are yet to fill a greater niche especially in the automotive and aeronautical industry. In fact, such alloys have a big weight saving potential, together with good damping characteristics. However, nowadays about 90% of Magnesium products are produced by casting, mainly using two alloy systems, namely Mg-Al-Zn (AZ91D) and Mg-Al (AM50, AM60). Now the emphasis, especially after having achieved considerable success in creep resistance and understanding of the deformation behaviour of Magnesium, has been shifted towards wrought alloys; AZ31, in this case, is the most popular. In this work a multi-element Magnesium alloy, developed to improve the deformation capacity of such a lightweight material, has been investigated and compared to a commercial AZ31B. The possibility of adopting such a multi-element Magnesium alloy for manufacturing components via unconventional sheet forming (such as superplastic forming, warm hydroforming, incremental forming) has been proved in the present work focusing the attention on the superplastic field. Free inflation tests were thus conducted at 450°C setting constant pressure to investigate the superplastic behaviour (in terms of dome height and strain rate sensitivity index) of both the multi-element Magnesium alloy (Mg-2Zn-Ce) and the commercial one (AZ31B). To enhance information on the thickness distribution and investigate the microstructure evolution, metallographic analyses on the samples used to carry out free inflation tests were also performed. The developed ternary alloy manifested quite a good deformation behaviour (high strain rate sensitivity index), even being tested in the as cast condition; in addition a limited grain coarsening was observed in the specimens after deformation.

Synthesis of nanocrystalline magnesium nitride (Mg3N2) powder using thermal plasma

International Nuclear Information System (INIS)

Kim, Dong-Wook; Kim, Tae-Hee; Park, Hyun-Woo; Park, Dong-Wha

2011-01-01

Nanocrystalline magnesium nitride (Mg 3 N 2 ) powder was synthesized from bulk magnesium by thermal plasma at atmospheric pressure. Magnesium vapor was generated through heating the bulk magnesium by DC plasma jet and reacted with ammonia gas. Injecting position and flow rates of ammonia gas were controlled to investigate an ideal condition for Mg 3 N 2 synthesis. The synthesized Mg 3 N 2 was cooled and collected on the chamber wall. Characteristics of the synthesized powders for each experimental condition were analyzed by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and thermogravity analysis (TGA). In absence of NH 3 , magnesium metal powder was formed. The synthesis with NH 3 injection in low temperature region resulted in a formation of crystalline magnesium nitride with trigonal morphology, whereas the mixture of magnesium metal and amorphous Mg 3 N 2 was formed when NH 3 was injected in high temperature region. Also, vaporization process of magnesium was discussed.

THE FORMING OF MAGNESIUM ALLOY FORGINGS FOR AIRCRAFT AND AUTOMOTIVE APPLICATIONS

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Anna Dziubińska

2016-09-01

Full Text Available The paper presents the theoretical and technological aspects of forming magnesium alloy parts for aircraft and automotive applications. The main applications of magnesium alloys in the aircraft and automotive industries are discussed. In addition, the forging technology for magnesium alloys is generally described, with a particular emphasis on wrought alloys. A brief outline of the state of the art in the forging of magnesium alloys is given based on a survey of the specialist literature and the results of previous research by the authors.

Lithium-aluminum-magnesium electrode composition

Science.gov (United States)

Melendres, Carlos A.; Siegel, Stanley

1978-01-01

A negative electrode composition is presented for use in a secondary, high-temperature electrochemical cell. The cell also includes a molten salt electrolyte of alkali metal halides or alkaline earth metal halides and a positive electrode including a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent and a magnesium-aluminum alloy as a structural matrix. Various binary and ternary intermetallic phases of lithium, magnesium, and aluminum are formed but the electrode composition in both its charged and discharged state remains substantially free of the alpha lithium-aluminum phase and exhibits good structural integrity.

Magnesium and uranium ignition in different gaseous atmospheres

International Nuclear Information System (INIS)

Darras, R.; Baque, P.; Leclercq, D.

1960-01-01

Magnesium, uranium and some of their alloys burning temperatures have been systematically determined in an air or carbon dioxide atmosphere, either dry or wet. Two different ways of heating have been used: either continuously rising up the temperature, or heating to and then maintaining a constant temperature. The results are clearly different in the two cases. Besides, if moisture has little effect on the magnesium burning temperatures in air, it does lower them by about 130-140 deg. C in CO 2 . The differences of sight between the burning of magnesium and uranium have been noticed; this leads to distinguish between an 'ignition' and an 'inflammation'. (author) [fr

Recent research and developments on wrought magnesium alloys

Directory of Open Access Journals (Sweden)

Sihang You

2017-09-01

Full Text Available Wrought magnesium alloys attract special interests as lightweight structural material due to their homogeneous microstructure and enhanced mechanical properties compared to as-cast alloys. In this contribution, recent research and developments on wrought magnesium alloys are reviewed from the viewpoint of the alloy design, focusing on Mg-Al, Mg-Zn and Mg-rare earth (RE systems. The effects of different alloying elements on the microstructure and mechanical properties are described considering their strengthening mechanisms, e.g. grain refinement, precipitation and texture hardening effect. Finally, the new alloy design and also the future research of wrought magnesium alloys to improve their mechanical properties are discussed.

Research of Plasma Spraying Process on Aluminum-Magnesium Alloy

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Patricija Kavaliauskaitė

2016-04-01

Full Text Available The article examines plasma sprayed 95Ni-5Al coatings on alu-minum-magnesium (Mg ≈ 2,6‒3,6 % alloy substrate. Alumi-num-magnesium samples prior spraying were prepared with mechanical treatment (blasting with Al2O3. 95Ni-5Al coatings on aluminum-magnesium alloys were sprayed with different parameters of process and coating‘s thickness, porosity, micro-hardness and microstructure were evaluated. Also numerical simulations in electric and magnetic phenomena of plasma spray-ing were carried out.

Plasma Magnesium and the Risk of Ischemic Stroke among Women

Science.gov (United States)

Akarolo-Anthony, Sally N.; Jiménez, Monik C.; Chiuve, Stephanie E.; Spiegelman, Donna; Willett, Walter C.; Rexrode, Kathryn M.

2014-01-01

Background and Purpose Lower plasma magnesium levels may be associated with higher blood pressure and endothelial dysfunction, but sparse prospective data are available for stroke. Methods Among 32,826 participants in the Nurses’ Health Study who provided blood samples in 1989–1990, incident ischemic strokes were identified and confirmed by medical records through 2006. We conducted a nested case-control analysis of 459 cases, matched 1:1 to controls on age, race/ethnicity, smoking status, date of blood draw, fasting status, menopausal status and hormone use. We used conditional logistic regression models to estimate the multivariable adjusted association of plasma magnesium and the risk of ischemic stroke and ischemic stroke subtypes. Results Median magnesium levels did not differ between ischemic stroke cases and controls (median=0.86 mmol/l for both; p-value=0.14). Conditional on matching factors, women in the lowest magnesium quintile had a relative risk (RR) of 1.34 (95% confidence interval [CI]: 0.86–2.10, p trend=0.13) for total ischemic stroke, compared to women in the highest quintile. Additional adjustment for risk factors and confounders did not substantially alter the risk estimates for total ischemic stroke. Women with magnesium levels magnesium levels ≥0.82 mmol/l. No significant effect modification was observed by age, body mass index, hypertension or diabetes. Conclusions Lower plasma magnesium levels may contribute to higher risk of ischemic stroke among women. PMID:25116874

Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts; Apport des isotopes stables a l'etude de la pharmacocinetique de sels de magnesium

Energy Technology Data Exchange (ETDEWEB)

Benech, H

1999-05-28

The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, {sup 25}Mg and {sup 26}Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

Comportamiento parabólico del crecimiento de capas boradas en los aceros Y8A y X12M // Parabolic behavior of boriding layers growth in Y8A and X12M steels

Directory of Open Access Journals (Sweden)

C. Figueroa Hernández

1999-01-01

Full Text Available Se determina la influencia que tienen los principales parámetros tecnológicos del borado en el crecimiento de las capas y secorrobora el cumplimiento de la ley parabólica para predecir este comportamiento en los aceros Y8A y X12M.El proceso de borado se aplica en una mezcla de carburo de silicio y bórax (70 y 30 % a la temperatura de 850, 900 y 950 oCdurante un tiempo de 2, 4 y 6 horas. Como variable dependiente se seleccionó la profundidad del recubrimiento, a partir de lacual se obtuvieron los coeficientes del crecimiento parabólico y la energía de activación en función de la temperatura, el tiempodel proceso y el tipo de acero.La caracterización metalográfica reveló la presencia de la fase Fe2BPalabras claves: Borado, recubrimiento superf icial , t ecnología de recubrimiento.__________________________________________________________________________AbstractIt was determined the influence of the main technological parameters of the boriding process, and a mathematical model thatallows to predict this conduct on the steels Y8A and X12M steels was obtained.The boriding process is applied in a mixture of silicon carbide and borax (70 and 30% at 850, 900 and 950 oC temperatureduring a period of time 2, 4 and 6 hours. As an independent variable the depth of the coat was selected.It was obtained the parabolic growth coefficients, and the activation energy according to temperature, time and the chemicalcomposition of steel.Metallografic analysis reveals the presence of Fe2B phase.Key words: Boriding process, superf icial coat , coat technology.

The coloring problem in the solid-state metal boride carbide ScB{sub 2}C{sub 2}. A theoretical analysis

Energy Technology Data Exchange (ETDEWEB)

Lassoued, Souheila [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques; Universite Kasdi Merbah-Ouargla (Algeria). Faculte des Mathematiques et des Sciences de la Matiere; Boucher, Benoit [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques; Max-Planck-Institut fuer Chemische Physik Fester Stoffe, Dresden (Germany); Boutarfaia, Ahmed [Universite Kasdi Merbah-Ouargla (Algeria). Faculte des Mathematiques et des Sciences de la Matiere; Gautier, Regis; Halet, Jean-Francois [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques

2016-08-01

The electronic properties of the layered ternary metal boride carbide ScB{sub 2}C{sub 2}, the structure of which consists of B/C layers made of fused five- and seven-membered rings alternating with scandium sheets, are analyzed. In particular, the respective positions of the B and C atoms (the so-called coloring problem) are tackled using density functional theory, quantum theory of atoms in molecules, and electron localizability indicator calculations. Results reveal that (i) the most stable coloring minimizes the number of B-B and C-C contacts and maximizes the number of boron atoms in the heptagons, (ii) the compound is metallic in character, and (iii) rather important covalent bonding occurs between the metallic sheets and the boron-carbon network.

Determination of calcium and magnesium in nuclear grade alumina by ion chromatography technique

International Nuclear Information System (INIS)

Hespanhol, E.C.B.; Pires, M.A.F.; Atalla, L.T.

1987-07-01

A simple method for solubilization of alumina and separation of magnesium and calcium from alumina matrix was developed by initial coprecipitation of those elements with iron(III) hydroxide. Calcium and magnesium were later separated from iron chloride anionic complex in a Dowex 1-X 10 anionic exchange resin. The ion chromatography tecnnique was employed for the analysis of calcium and magnesium. One hundred percent recovery for calcium and magnesium was obtained in their separation from alumina. A precision of 6% and 10% for magnesium and calcium, respectively, was obtained in alumina samples analysis which contain less than 0,02% of magnesium and less than 0,08% of calcium. (Author) [pt

Effectivness of dexametasone vs. Magnesium sulphate in postoperative analgesia: Dexametasone vs. Magnesium sulphate

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Dautaj Brikena

2016-01-01

Full Text Available Introduction: Preoperative use of additive substances may be very helpful in perioperative acute pain management. Intravenous administration of dexametasone in preoperative period prevents postoperative nausea and vomiting but also provides better pain relief. It is also well known that magnesium sulphate (the NMDA receptor's antagonist by its central mechanism of action may be effective in postoperative pain control. Aim: The purpose of this study was to evaluate the effect of dexametasone and magnesium sulphate on postoperative pain management in patients undergoing abdominal surgery (open cholecystectomy. Methods: Seventy eight patients scheduled for elective surgery (open cholecystectomy were included in this study. This was the prospective cohort randomized placebo- controlled study. A total of 78 patients were randomized into three groups. Each group had twenty six patients. The group D, received dexametasone 0.1 mg/ kg iv 30 minutes before surgery. The group M received magnesium sulphate 3 mg/kg iv 30 minutes before surgery. The third group S was placebo group and patients in this group received saline in the same volume for each patient. For pain control after surgery all patients received tramadol 0.9-1.2 mg/kg and diklophenac 1.76 mg/kg. When necessary (VAS ≥ 7, morphine sulphate in dose 0.15 mg/kg was administred subcutaneously For treatment of emetic episodes metoclopramid 10 mg iv. was used. The patients were observed for intensity of pain measured VAS 0-10, pain relief and satisfaction with therapy, sedation, adverse events, emetic episodes and hemodynamic parameters. Results: There was no difference between groups regarding demographic data (age, gender, body weight, ASA score, comorbidity, duration of surgery and anesthesia and amount of fentanyl received during surgery. In group D 11.54% of patients received additional analgesia (morphine sulphate 0.15 mg/kg sc in the first 4 hours and 27% of patients in the first 24 hours

Magnesium prevents vascular calcification in vitro by inhibition of hydroxyapatite crystal formation.

NARCIS (Netherlands)

Braake, A.D. ter; Tinnemans, P.T.; Shanahan, C.M.; Hoenderop, J.G.J.; Baaij, J.H.F. de

2018-01-01

Magnesium has been shown to effectively prevent vascular calcification associated with chronic kidney disease. Magnesium has been hypothesized to prevent the upregulation of osteoblastic genes that potentially drives calcification. However, extracellular effects of magnesium on hydroxyapatite

Mechanistic origin and prediction of enhanced ductility in magnesium alloys

Science.gov (United States)

Wu, Zhaoxuan; Ahmad, Rasool; Yin, Binglun; Sandlöbes, Stefanie; Curtin, W. A.

2018-01-01

Development of ductile magnesium alloys is key to their use in reducing the weight of vehicles and other applications. Wu et al. tackle this issue by determining the underlying mechanisms in unprocessed magnesium alloys. Dilute amounts of solutes enhanced certain ductility-improving mechanisms over ones that cause brittle fracture. From this, the authors developed a theory that may be helpful for screening the large number of potential magnesium alloy compositions.

Magnesium and metabolic syndrome: The role of magnesium in health and disease

Science.gov (United States)

Metabolic syndrome is a constellation of conditions associated with elevated risk of diabetes and cardiovascular disease. Magnesium, the fourth most abundant cation in the human body and required in over 300 enzymatic reactions, has been shown in experimental, observational, and clinical studies to ...

Enzymatic, urease-mediated mineralization of gellan gum hydrogel with calcium carbonate, magnesium-enriched calcium carbonate and magnesium carbonate for bone regeneration applications

DEFF Research Database (Denmark)

Douglas, Timothy E L; Łapa, Agata; Samal, Sangram Keshari

2017-01-01

enzymatically with CaCO3 , Mg-enriched CaCO3 and magnesium carbonate to generate composite biomaterials for bone regeneration. Hydrogels loaded with the enzyme urease were mineralized by incubation in mineralization media containing urea and different ratios of calcium and magnesium ions. Increasing...

Suppression of exercise-induced angina by magnesium sulfate in patients with variant angina

International Nuclear Information System (INIS)

Kugiyama, K.; Yasue, H.; Okumura, K.

1988-01-01

The effects of intravenous magnesium on exercise-induced angina were examined in 15 patients with variant angina and in 13 patients with stable effort angina and were compared with those of placebo. Symptom-limited bicycle exercise and thallium-201 myocardial scintigraphy were performed after intravenous administration of 0.27 mmol/kg body weight of magnesium sulfate and after placebo on different days. In all patients, serum magnesium levels after administration of magnesium sulfate were about twofold higher than levels after placebo. Exercise-induced angina associated with transient ST segment elevation occurred in 11 patients with variant angina receiving placebo and in only 2 of these patients receiving magnesium (p less than 0.005). On the other hand, exercise-induced angina was not suppressed by magnesium in any patient with stable effort angina. In these patients there was no significant difference in exercise duration after administration of placebo versus after administration of magnesium. The size of the perfusion defect as measured by thallium-201 scintigraphy was significantly less in patients with variant angina receiving magnesium than that in those receiving placebo (p less than 0.001), whereas it was not significantly different in patients with stable effort angina receiving placebo versus magnesium. In conclusion, exercise-induced angina is suppressed by intravenous magnesium in patients with variant angina but not in patients with stable effort angina. This beneficial effect of magnesium in patients with variant angina is most likely due to improvement of regional myocardial blood flow by suppression of coronary artery spasm

IFCC guideline for sampling, measuring and reporting ionized magnesium in plasma

DEFF Research Database (Denmark)

Rayana, M.C. Ben; Burnett, R.W.; Covington, A.K.

2008-01-01

Analyzers with ion-selective electrodes (ISEs) for ionized magnesium (iMg) should yield comparable and unbiased results for iMg. This IFCC guideline on sampling, measuring and reporting iMg in plasma provides a prerequisite to achieve this goal [in this document, "plasma" refers to circulating...... plasma and the forms in which it is sampled, namely the plasma phase of anticoagulated whole blood (or "blood"), plasma separated from blood cells, or serum]. The guideline recommends measuring and reporting ionized magnesium as a substance concentration relative to the substance concentration...... of magnesium in primary aqueous calibrants with magnesium, sodium, and calcium chloride of physiological ionic strength. The recommended name is "the concentration of ionized magnesium in plasma". Based on this guideline, results will be approximately 3% higher than the true substance concentration and 4...

Effects of magnesium sulfate on the foliar absorption of phosphates at the pumpkin; Effets du sulfate de magnesium sur l'absorption foliaire de phosphates chez le potiron

Energy Technology Data Exchange (ETDEWEB)

Chamel, A

1962-07-01

The foliar absorption of phosphates labelled with {sup 32}P and applied with or without magnesium sulfate on the first leaf of pumpkin seedlings have been studied. The magnesium sulfate applied with the phosphate reduces plainly the absorption rate of {sup 32}P. (O.M.) [French] Nous avons etudie l'absorption foliaire de phosphates marques au {sup 32}P appliques, avec et sans sulfate de magnesium, sur la premiere feuille de jeunes plants de potirons. Le sulfate de magnesium applique avec le phosphate diminue nettement le taux d'absorption du {sup 32}P. (auteur)

Synthesis of magnesium aluminate spinel by periclase and alumina chlorination

International Nuclear Information System (INIS)

Orosco, Pablo; Barbosa, Lucía; Ruiz, María del Carmen

2014-01-01

Highlights: • Use of chlorination for the synthesis of magnesium aluminate spinel. • The reagents used were alumina, periclase and chlorine. • Isothermal and non-isothermal assays were performed in air and Cl 2 –N 2 flows. • The chlorination produced magnesium aluminate spinel at 700 °C. • Selectivity of the chlorination reaction to obtain spinel is very high. - Abstract: A pyrometallurgical route for the synthesis of magnesium aluminate spinel by thermal treatment of a mechanical mixture containing 29 wt% MgO (periclase) and 71 wt% Al 2 O 3 (alumina) in chlorine atmosphere was developed and the results were compared with those obtained by calcining the same mixture of oxides in air atmosphere. Isothermal and non-isothermal assays were performed in an experimental piece of equipment adapted to work in corrosive atmospheres. Both reagents and products were analyzed by differential thermal analysis (DTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Thermal treatment in Cl 2 atmosphere of the MgO–Al 2 O 3 mixture produces magnesium aluminate spinel at 700 °C, while in air, magnesium spinel is generated at 930 °C. The synthesis reaction of magnesium aluminate spinel was complete at 800 °C

Raman spectra of hot-pressed boron suboxide

CSIR Research Space (South Africa)

Machaka, R

2011-01-01

Full Text Available on in- situ/online measurements (such as GIXRD, Raman Spectroscopy, FIB- Electron Microscopy) during (i) ion implantation, (ii) PLD growth of nanoparticles SW/MW-CNTs, oxide semiconductor multi-layer, metal/Si and metal/metal systems. Moreover, He...], aluminium magnesium boride ? AlMgB14 [8], and the newly synthesized boron subnitride ? B13N2 [9, 10]. With hardness values reported between 24 GPa and 45 GPa [7, 11, 12], B6O is sometimes considered to be the third hardest material only after diamond...

Reactions of zinc hydride and magnesium hydride with pyridine; synthesis and characterization of 1,4-dihydro-1-pyridylzinc and -magnesium complexes

NARCIS (Netherlands)

Koning, A.J. de; Boersma, J.; Kerk, G.J.M. van der

1980-01-01

The synthesis and characterization of 1,4-dihydro-1-pyridylzinc and -magnesium complexes are described. Zinc hydride and magnesium hydride dissolve in and react with pyridine, and the reaction has been studied in detail in the case of zinc hydride. Evaporation of the solvent after 1–2 hours at 0°C

Safety and efficacy of Bolus administration of magnesium sulphate ...

African Journals Online (AJOL)

Safety and efficacy of Bolus administration of magnesium sulphate for preeclampsia. ... On-going research is addressing its administration in terms of dosage, duration and safety. Objective: We evaluated a ... Keywords: safety, efficacy, bolus magnesium sulphate, preeclampsia, University of Benin Teaching Hospital

Electron microscope study of vacancy clusters produced by quenching in magnesium; Etude par microscopie electronique des amas de lacunes crees par trempe dans le magnesium

Energy Technology Data Exchange (ETDEWEB)

Levy, V; Espinasse, J; Mairy, C; Hillairet, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-07-01

Vacancy clustering in quenched magnesium has been studied by transmission electron microscopy. The nature of the vacancy loops observed, seems to depend essentially on the impurity content of the metal; this effect can be attributed to a variation of the stacking fault energy of magnesium due to impurities. (authors) [French] On a etudie par microscopie electronique en transmission les defauts crees par trempe dans le magnesium. Un effet considerable des impuretes du metal sur la nature des boucles obtenues par condensation de lacunes a ete mis en evidence; cet effet semble s'expliquer de facon satisfaisante par un abaissement de l'energie de faute d'empilement du magnesium du aux impuretes. (auteur)

The influence of modification on the thermophysical properties of magnesium wrought alloys

NARCIS (Netherlands)

Moldovan, P.; Popescu, G.; Miculescu, M.; Bojin, D.; Dimitriu, S.; Sillekens, W.H.

2009-01-01

Magnesium is the lightest engineering metal and has a great potential due to its raw material large natural reverse and interesting properties. Magnesium alloys are attracting increasing attention for industry for weight reduction and high fuel efficiency. Magnesium alloys are attractive

Magnesium and its transport in tilapia and carp: A study based on nuclear methods. Thesis

Energy Technology Data Exchange (ETDEWEB)

van der Velden, J.A.

1993-01-01

The experiments described in this thesis deal with the production of radiotracers for magnesium and the magnesium metabolism of freshwater tilapia and carp. In chapter 2 the technique of instrumental neutron activation analysis, and the production and properties of two radioisotopes of magnesium are described. In chapter 3 the magnesium distribution and the magnesium inventory of carp and tilapia is described, mainly by the use of instrumental neutron activation analysis. Chapter 4 deals with magnesium transport (in vivo and in vitro) between the water and fish and food and fish. In chapter 5 effects of a low-magnesium diet on tissue mineral concentrations, on the ion regulation and on magnesium transport of fish is described. Chapter 6 deals with the effects of low ambient magnesium on early life stages of the fish.

Magnesium sacrificial anode behavior at elevated temperature

International Nuclear Information System (INIS)

Othman, Mohsen Othman

2006-01-01

Magnesium sacrificial anode coupled to mild steel was tasted in sodium chloride and tap water environments at elevated temperatures. The anode failed to protect the mild steel specimens in tap water environment at all temperatures specified. This was partly due to low conductivity of this medium. The temperature factor did not help to activate the anode in this medium. In sodium chloride environment the anode demonstrated good protection for steel cathodes. The weight loss was high for magnesium in sodium chloride environment particularly beyond 60 degree centigrade. In tap water environment the weight loss was negligible for the anode. It also suffered localized shallow pitting corrosion. Magnesium anode cannot be utilized where high temperature is involved particularly in high conductivity mediums. Protection of structures containing high resistivity waters is not feasible using sacrificial anode system. (author)

EFFECTS OF MAGNESIUM PEMOLINE UPON HUMAN LEARNING, MEMORY, AND PERFORMANCE TESTS.

Science.gov (United States)

SMITH, RONALD G.

THIS STUDY WAS CONDUCTED DURING 1966 TO DETERMINE THE EFFECTS OF MAGNESIUM PEMOLINE (A COMBINATION OF 2-IMINO-5-PHENYL-4-OXAZOLIDINONE AND MAGNESIUM HYDROXIDE) ON A VARIETY OF HUMAN LEARNING, MEMORY, AND PERFORMANCE TASKS. MAGNESIUM PEMOLINE (25 OR 37.5 MG) OR A PLACEBO WAS ADMINISTERED ORALLY ON A DOUBLE-BLIND BASIS TO INTELLIGENCE-MATCHED GROUPS…

Korelasi Kadar Magnesium Serum dengan Albuminuria pada Pasien Diabetes Melitus Tipe 2

Directory of Open Access Journals (Sweden)

Tri Juli Edi Tarigan

2015-12-01

Full Text Available Tujuan penelitian ini adalah untuk mengetahui peran magnesium pada nefropati diabetes dan mendapatkan proporsi albuminuria pada pasien DM tipe 2 dengan hipomagnesemia dan magnesium normal serta mendapatkan korelasi kadar Mg dengan albuminuria. Penelitian menggunakan desain cross sectional dengan consecutive sampling pada pasien DM tipe 2 yang terdiagnosis nefropati diabetes di Poliklinik Diabetes RSCM pada bulan Maret-Juni 2014. Dilakukan anamnesis faktor risiko, pemeriksaan fisik, kadar magnesium, albumine creatinine ratio dan A1C. Terdapat 38 subjek yang diikutsertakan dalam penelitian yang sebagian besar berusia lebih 50 tahun dan memiliki kontrol glikemik yang buruk (81,6%. Pada subjek penelitian yang memiliki kadar Mg<1,7 mg/dl 80% mengalami albuminuria, sedangkan pada subjek yang memiliki kadar Mg ≥ 1,7 mg/ dl sebanyak 63,6% mengalami albuminuria. Didapatkan koefisien korelasi sebesar 0,006 yang menunjukkan hubungan yang lemah antara kadar magnesium dalam darah dengan albuminuria. Disimpulkan tidak terdapat korelasi antara kadar magnesium dengan derajat albuminuria. Kata kunci: kadar magnesium, albuminuria, diabetes melitus tipe 2   Correlation between Magnesium Level and Albuminuria in Patients with Type 2 Diabetes Abstract The purposes of this study are to know: the role of magnesium in diabetic nephropathy, the proportion of albuminuria in type 2 DM with hypomagnesemia and normal magnesium level, and correlation between magnesium level and albuminuria. This cross-sectional study was done in Diabetes Clinic RSCM from March to June 2014 with consecutive sampling for type 2 DM patients who had been diagnosed with diabetic nephropathy. History taking, physical exam, albumin creatinine ratio test, and A1c level were done. Thirty eight subjects included in this study were mostly more than 50 years old and had poor glycemic control (81,6%. 80% of subjects with Mg level < 1.7 mg/dl experienced albuminuria and 63.6% of subjects with Mg level

Influence of corrosive solutions on microhardness and chemistry of magnesium oxide /001/ surfaces

Science.gov (United States)

Ishigaki, H.; Miyoshi, K.; Buckley, D. H.

1982-01-01

X-ray photoelectron spectroscopy analyses and hardness experiments were conducted on cleaved magnesium oxide /001/ surfaces. The magnesium oxide bulk crystals were cleaved to specimen size along the /001/ surface, and indentations were made on the cleaved surface in corrosive solutions containing HCl, NaOH, or HNO3 and in water without exposing the specimen to any other environment. The results indicated that chloride (such as MgCl2) and sodium films are formed on the magnesium oxide surface as a result of interactions between an HCl-containing solution and a cleaved magnesium oxide surface. The chloride films soften the magnesium oxide surface. In this case microhardness is strongly influenced by the pH value of the solution. The lower the pH, the lower the microhardness. Sodium films, which are formed on the magnesium oxide surface exposed to an NaOH containing solution, do not soften the magnesium oxide surface.

Distribution of magnesium in groundwater of Serbia

OpenAIRE

Milosavljević Jovana; Andrijašević Jakov; Todorović Maja

2013-01-01

Magnesium is chemical element commonly found in the environment and the main constituent of many types of minerals and rocks. This element is also essential to man. Owing to its abundance in nature, magnesium is present in all water resources and generally occur as the dominant cation, with calcium, in those that feature low TDS levels, whose origin is associated with large formations of sedimentary rocks (limestones, dolomites), and to a lesser extent with...

The Importance of Magnesium in the Human Body: A Systematic Literature Review

DEFF Research Database (Denmark)

Glasdam, Sidsel-Marie; Glasdam, Stinne; Peters, Günther H.J.

2016-01-01

Magnesium, the second and fourth most abundant cation in the intracellular compartment and whole body, respectively, is of great physiologic importance. Magnesium exists as bound and free ionized forms depending on temperature, pH, ionic strength, and competing ions. Free magnesium participates...

Distinction between magnesium diboride and tetraboride by kelvin probe force microscopy; Unterscheidung von Magnesiumdiborid und Magnesiumtetraborid durch Kelvinsondenkraftmikroskopie

Energy Technology Data Exchange (ETDEWEB)

Kim, Du-Na; Caron, Arnaud; Park, Hai Woong [KoreaTech - Korea Univ. of Technology and Education, Chungnam (Korea, Republic of). School of Energy, Materials and Chemical Engineering

2016-08-15

We analyze mixtures of magnesium diboride and tetraboride synthesized with magnesium powders of different shapes. To distinguish between magnesium diboride and tetraboride we use the contrast of kelvin probe force microscopy. The microstructural morphology strongly depends on the shape of the magnesium powders used in the reaction between magnesium and magnesium tetraboride to form magnesium diboride. With spherical magnesium powder an equiaxed microstructure of magnesium diboride is formed with residual magnesium tetraboride at the grain boundaries. With plate-like magnesium powders elongated magnesium diboride grains are formed. In this case, residual magnesium tetraboride is found to agglomerate.

HUBUNGAN ASUPAN MAGNESIUM DAN KADAR GLUKOSA DARAH PUASA PASIEN RAWAT JALAN DIABETES MELITUS TIPE 2 (CORRELATION BETWEEN MAGNESIUM INTAKE AND FASTING BLOOD GLUCOSE LEVEL IN OUTPATIENTS WITH TYPE 2 DIABETES MELLITUS

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Anggun Faradhita

2014-12-01

Diabetes Mellitus type 2 reveals resistance insulin. Inadequate magnesium consumption has been reported to promote insulin resistance. The potential role of magnesium in Diabetes Mellitus is improving insulin sensitivity. Previous studies indicated that there is an inverse correlation between magnesium intakes and the incidence of type 2 Diabetes. This study aimed to analyze the association between magnesium intake and fasting blood glucose levels in outpatients with Type 2 Diabetes Mellitus in Al Ihsan Hospital. Cross-sectional study in 46 participants was taken by purposive sampling. Data collection was conducted in June-July 2013 which included common data, exercise habits, nutritional status, energy intake, magnesium intake, protein intake, fiber intake and fasting blood glucose levels. This research showed that there was a significant association between magnesium intake and fasting blood glucose levels of patients (p < 0.001 with a correlation of moderate strength (r = -0.562, high magnesium intake was followed by a decrease in fasting blood glucose levels. It is then suggested that people with diabetes mellitus consume adequate amounts of magnesium and set a good diet and regular exercise as a step in the control of blood glucose levels. Keywords: Magnesium Intake, Fasting Blood Glucose, Type 2 Diabetes Mellitus

ROLE OF MAGNESIUM IN HEADACHE PATHOGENESIS IN CHILDREN AND ADOLESCENTS

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E. S. Akarachkova

2013-01-01

Full Text Available Article is dedicated to the problem of headache in children. This pathology is being found more frequently in pediatric and children’s neurologic practice. The authors examine headache pathogenesis from the position of magnesium deficiency. Analysis of results of the modern studies on magnesium deficiency and its correction in patients with headache indicates that magnesium metabolism may play an important role both in pathogenesis of different headache types and in its treatment and prevention.

Severe selective magnesium malabsorption: tests of tolerance of oral magnesium supplements.

Science.gov (United States)

Mettey, R; Guillard, O; Merle, P; Maillet-Picker, F

1990-12-01

Since his birth, we have been monitoring a 12-year-old boy suffering from selective severe magnesium malabsorption. Our essential problem is to prepare a form of galena with acceptable taste, tolerated by the digestive tract and well absorbed; also, the carrier compound must not cause short- or long-term side effects. An additional factor is the steadily increasing need for magnesium from 1 mmol/kg.d at 1 year to 14 mmol/kg.d at present age (345 mg/kg.d). The galena forms currently on sale were, with the exception of lactate and pyrollidone carboxylate, immediately rejected since they contain insufficient Mg2+. Following short trials resulting in diarrhoea, the other two preparations were also rejected. We then constituted - and also abandoned - our own galena compounds: aspartate (bitterness), aspartate + glycerophosphate (GLP) (bitterness), glutamate + GLP ('Chinese restaurant syndrome' and fear of the long term toxic effect of the glutamate), gluconate (excessive volume: 11/1 proportion with Mg2+). A recent test featuring GLP of Mg 40 g + cocoa butter 40 g + cocoa 10 g, brought about vomiting and diarrhoea, and was not adequately absorbed. The best tolerated formula is: Mg GLP 21.33 g; saccharose 6 g; aspartam 1 g; gelatin 0.5 g; citric acid, conserving agent, fruity aroma; water: qs 100 g. Such composition yields a caramel cream absorbed in five small portions, at a daily quantity of 375 g (80 g GLP Mg, 10 g Mg2+). Vitamin B6, which promotes intestinal absorption of magnesium, must be given separately in tablet form at a dose of 1 g/d, since it causes nausea if it is included in the Mg preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Heated Hydro-Mechanical Deep Drawing of Magnesium Sheet Metal

Science.gov (United States)

Kurz, Gerrit

In order to reduce fuel consumption efforts have been made to decrease the weight of automobile constructions by increasing the use of lightweight materials. In this field of application magnesium alloys are important because of their low density. A promising alternative to large surfaced and thin die casting parts has been found in construction parts that are manufactured by sheet metal forming of magnesium. Magnesium alloys show a limited formability at room temperature. A considerable improvement of formability can be achieved by heating the material. Formability increases above a temperature of approximately T = 225 °C.

Controlling the ignition and flammability of magnesium for aerospace applications

International Nuclear Information System (INIS)

Czerwinski, Frank

2014-01-01

The perceived easy ignition and flammability of magnesium alloys create a detrimental safety feature that overshadows their high strength-to-weight ratio and hinders the aerospace application opportunities. To overcome the existing barriers a progress in understanding and controlling the reactivity of magnesium at high temperatures is required. This report describes fundamentals of magnesium ignition and flammability along with laboratory testing procedures and correlations with full scale fire scenarios, related in particular to the aircraft cabin. The influence of alloying elements on high temperature reactivity of magnesium and global efforts to develop ignition resistant and non-flammable magnesium alloys are reviewed. Although ignition and flammability represent quite different quantities, both are controlled by an oxidation resistance of the alloy and its capability to form a dense and protective surface oxide after exposures to an open flame or other heat source. Since surface oxide, composed of pure MgO, does not offer a sufficient protection, the research strategy is focused on modification of its chemistry and microstructure by micro-alloying the substrate with rare earths and other elements having high affinity to oxygen

Surface characterization and cytotoxicity response of biodegradable magnesium alloys

International Nuclear Information System (INIS)

Pompa, Luis; Rahman, Zia Ur; Munoz, Edgar; Haider, Waseem

2015-01-01

Magnesium alloys have raised an immense amount of interest to many researchers because of their evolution as a new kind of third generation materials. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium alloys experience a natural phenomenon to biodegrade in aqueous solutions due to its corrosion activity, which is excellent for orthopedic and cardiovascular applications. However, a major concern with such alloys is fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of biodegradable implants. In this investigation, three different grades of magnesium alloys: AZ31B, AZ91E and ZK60A were studied for their corrosion resistance and biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter are used to study surface morphology, chemistry, roughness and wettability, respectively. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium based bio-assay, MTS. - Highlights: • Micro-textured features formed after the anodization of magnesium alloys. • Contact angle increased and surface free energy decreased by anodization. • Corrosion rate increased for anodized surfaces compared to untreated samples. • Cell viability was greater than 75% implying the cytocompatibility of Mg alloys

Effects of calcium and magnesium on strontium distribution coefficients

Science.gov (United States)

Bunde, R.L.; Rosentreter, J.J.; Liszewski, M.J.; Hemming, C.H.; Welhan, J.

1997-01-01

The effects of calcium and magnesium on the distribution of strontium between a surficial sediment and simulated wastewater solutions were measured as part of an investigation to determine strontium transport properties of surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. The investigation was conducted by the U.S. Geological Survey and Idaho State University, in cooperation with the U.S. Department of Energy. Batch experimental techniques were used to determine strontium linear sorption isotherms and distribution coefficients (K(d)'s) using simulated wastewater solutions prepared at pH 8.0??0.1 with variable concentrations of calcium and magnesium. Strontium linear sorption isotherm K(d)'s ranged from 12??1 to 85??3 ml/g, increasing as the concentration of calcium and magnesium decreased. The concentration of sorbed strontium and the percentage of strontium retained by the sediment were correlated to aqueous concentrations of strontium, calcium, and magnesium. The effect of these cation concentrations on strontium sorption was quantified using multivariate least-squares regression techniques. Analysis of data from these experiments indicates that increased concentrations of calcium and magnesium in wastewater discharged to waste disposal ponds at the INEL increases the availability of strontium for transport beneath the ponds by decreasing strontium sorption to the surficial sediment.

Susceptibility of metallic magnesium implants to bacterial biofilm infections.

Science.gov (United States)

Rahim, Muhammad Imran; Rohde, Manfred; Rais, Bushra; Seitz, Jan-Marten; Mueller, Peter P

2016-06-01

Magnesium alloys have promising mechanical and biological properties as biodegradable medical implant materials for temporary applications during bone healing or as vascular stents. Whereas conventional implants are prone to colonization by treatment resistant microbial biofilms in which bacteria are embedded in a protective matrix, magnesium alloys have been reported to act antibacterial in vitro. To permit a basic assessment of antibacterial properties of implant materials in vivo an economic but robust animal model was established. Subcutaneous magnesium implants were inoculated with bacteria in a mouse model. Contrary to the expectations, bacterial activity was enhanced and prolonged in the presence of magnesium implants. Systemic antibiotic treatments were remarkably ineffective, which is a typical property of bacterial biofilms. Biofilm formation was further supported by electron microscopic analyses that revealed highly dense bacterial populations and evidence for the presence of extracellular matrix material. Bacterial agglomerates could be detected not only on the implant surface but also at a limited distance in the peri-implant tissue. Therefore, precautions may be necessary to minimize risks of metallic magnesium-containing implants in prospective clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1489-1499, 2016. © 2016 Wiley Periodicals, Inc.

Surface characterization and cytotoxicity response of biodegradable magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Pompa, Luis; Rahman, Zia Ur; Munoz, Edgar; Haider, Waseem, E-mail: haiderw@utpa.edu

2015-04-01

Magnesium alloys have raised an immense amount of interest to many researchers because of their evolution as a new kind of third generation materials. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium alloys experience a natural phenomenon to biodegrade in aqueous solutions due to its corrosion activity, which is excellent for orthopedic and cardiovascular applications. However, a major concern with such alloys is fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of biodegradable implants. In this investigation, three different grades of magnesium alloys: AZ31B, AZ91E and ZK60A were studied for their corrosion resistance and biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter are used to study surface morphology, chemistry, roughness and wettability, respectively. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium based bio-assay, MTS. - Highlights: • Micro-textured features formed after the anodization of magnesium alloys. • Contact angle increased and surface free energy decreased by anodization. • Corrosion rate increased for anodized surfaces compared to untreated samples. • Cell viability was greater than 75% implying the cytocompatibility of Mg alloys.

Interdiffusion of the aluminum magnesium system. Quantitative analysis and numerical model; Interdiffusion des Aluminium-Magnesium-Systems. Quantitative Analyse und numerische Modellierung

Energy Technology Data Exchange (ETDEWEB)

Seperant, Florian

2012-03-21

Aluminum coatings are a promising approach to protect magnesium alloys against corrosion and thereby making them accessible to a variety of technical applications. Thermal treatment enhances the adhesion of the aluminium coating on magnesium by interdiffusion. For a deeper understanding of the diffusion process at the interface, a quantitative description of the Al-Mg system is necessary. On the basis of diffusion experiments with infinite reservoirs of aluminum and magnesium, the interdiffusion coefficients of the intermetallic phases of the Al-Mg-system are calculated with the Sauer-Freise method for the first time. To solve contradictions in the literature concerning the intrinsic diffusion coefficients, the possibility of a bifurcation of the Kirkendall plane is considered. Furthermore, a physico-chemical description of interdiffusion is provided to interpret the observed phase transitions. The developed numerical model is based on a temporally varied discretization of the space coordinate. It exhibits excellent quantitative agreement with the experimentally measured concentration profile. This confirms the validity of the obtained diffusion coefficients. Moreover, the Kirkendall shift in the Al-Mg system is simulated for the first time. Systems with thin aluminum coatings on magnesium also exhibit a good correlation between simulated and experimental concentration profiles. Thus, the diffusion coefficients are also valid for Al-coated systems. Hence, it is possible to derive parameters for a thermal treatment by simulation, resulting in an optimized modification of the magnesium surface for technical applications.

Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts

International Nuclear Information System (INIS)

Benech, H.

1999-01-01

The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, 25 Mg and 26 Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

Structure and magnetic properties of the 3d transition-metal mono-borides TM–B (TM=Mn, Fe, Co) under pressures

International Nuclear Information System (INIS)

Bourourou, Y.; Beldi, L.; Bentria, B.; Gueddouh, A.; Bouhafs, B.

2014-01-01

In this paper, spin-polarization and pressure effects on the structural and electronic properties of the 3d transition-metal mono-borides TM–B (TM=Mn, Fe, Co) have been studied by using both local spin-density approximation (LSDA) and generalized gradient approximation (GGA) within the framework of density-functional theory (DFT). At equilibrium, spin-polarization calculations show that MnB and FeB compounds carry magnetic moment. The non-spin-polarization results show that the non-magnetic state is unstable for MnB and FeB compounds, but a stable non-magnetic phase for CoB compound, which is discussed in the framework of the well-known Stoner criterion. The calculated lattice parameters, bulk moduli, their first-pressure derivatives and magnetic moments agree well with experimental and other theoretical results. Significant differences in volume and in bulk modulus were found between the magnetic and non-magnetic case reached 4%, 22%, respectively. The effect of pressure on the crystal structure reflects in a compression of the unit cell volume with a decreasing in the magnetic moment. The density of states of MnB and FeB ferromagnetic compounds are significantly modified under high pressures. The exchange energy decreases with increasing pressure, at approximately V/V 0 =0.6, the exchange energy becomes absent in ferromagnetic compounds causes mirror in upper and lowers half panels. Finally, we notice that spin-polarization and pressure play a crucially important role in determining the electronic and structural properties of 3d transition-metal mono-borides. - Highlights: • Spin polarization and pressure effects on TM–B (TM=Mn, Fe, Co) have been investigated. • The non-spin-polarization results show that the non-magnetic state is stable for CoB. • The magnetic states of MnB and FeB are found more stable than their nonmagnetic states. • We report significant differences between the magnetic and non-magnetic cases. • The density of states of MnB and

The co-effect of collagen and magnesium ions on calcium carbonate biomineralization

International Nuclear Information System (INIS)

Jiao Yunfeng; Feng Qingling; Li Xiaoming

2006-01-01

The process of calcium carbonate biomineralization in the solution containing collagen and magnesium ions was studied in this paper. The results were characterized by using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect rules were obtained by the cooperation of collagen and magnesium ions in different concentration. The experiment results showed that in the presence of both collagen and magnesium ions, aragonite and vaterite were precipitated at low Mg/Ca ion concentration ratio, while only aragonite with regular spherical morphology was precipitated at high Mg/Ca ion concentration ratio. It indicated that collagen has a promotional effect on magnesium ions in controlling the polymorph of calcium carbonate crystal. A much wider range of calcium carbonate morphologies was observed in the presence of both collagen and magnesium ions. The experiments suggested that collagen acts in combination with magnesium ions to inhibit calcite crystal growth, while favoring the formation of aragonite crystals

Dielectric behaviour of sodium and potassium doped magnesium

Indian Academy of Sciences (India)

Pure phase of magnesium titanate (MgTiO3) was obtained at 1100°C by both the conventional solid-state method as well as by the flux method starting from hexahydrated magnesium nitrate and titanium dioxide as the reactants. MgTiO3 doped with Na or K was also prepared by the solid-state route. Na and K doped ...

Renal Control of Calcium, Phosphate, and Magnesium Homeostasis

Science.gov (United States)

Chonchol, Michel; Levi, Moshe

2015-01-01

Calcium, phosphate, and magnesium are multivalent cations that are important for many biologic and cellular functions. The kidneys play a central role in the homeostasis of these ions. Gastrointestinal absorption is balanced by renal excretion. When body stores of these ions decline significantly, gastrointestinal absorption, bone resorption, and renal tubular reabsorption increase to normalize their levels. Renal regulation of these ions occurs through glomerular filtration and tubular reabsorption and/or secretion and is therefore an important determinant of plasma ion concentration. Under physiologic conditions, the whole body balance of calcium, phosphate, and magnesium is maintained by fine adjustments of urinary excretion to equal the net intake. This review discusses how calcium, phosphate, and magnesium are handled by the kidneys. PMID:25287933

Performance, carcass and meat quality of ewes supplemented with magnesium oxide

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Camila Constantino

2014-01-01

Full Text Available The objective of this study was to evaluate the performance, the carcass and meat characteristics of ewes supplemented with magnesium oxide. Eighteen 6-year-old Santa Ines ewes were used in a completely randomized experimental design, where three levels of supplementation (0.0, 0.1 and 0.2% magnesium oxide in the concentrate were tested, with six replicates. Final weight, weight gain, feed intake and feed conversion were not affected by levels of magnesium supplementation. Hot and cold carcass weights showed linear increasing and quadratic responses, respectively, according to supplementation with magnesium. Carcass measurements such as length, depth, and measures of arm and leg were not affected by supplementation. Depth and width of the longissimus muscle and rib-eye area were not affected; however, marbling and ether extract increased linearly with supplementation. Water loss and color were not affected. Lipid oxidation and shear force were not affected by supplementation, while the myofibrillar fragmentation index showed a quadratic regression. There was a linear decrease in pH with magnesium supplementation. Supplementation with magnesium can improve carcass and meat pH, but can act negatively by increasing the amount of marbling and ether extract of meat.

Effects of silicon on mechanical properties of AM60 magnesium alloy

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Hu Yong

2012-08-01

Full Text Available Silicon was added to improve the tensile, wear and creep behaviors of AM60 magnesium alloy in this study. The investigation has been undertaken by means of universal testing machine, HBE-3000A Brinell hardness tester, M-2000 friction-wear machine, DMA-Q800 creep machine, optical microscopy (OM and scanning electron microscopy (SEM. The results indicate that the Chinese script type Mg2Si particles are formed by adding Si into the AM60 magnesium alloy. The ultimate tensile strength and hardness of the AM60 magnesium alloy increases with the Si addition, and the ultimate tensile strength and hardness of the AM60+1.0wt.%Si alloy are increased by 12% and 19.8%, respectively in comparison with that of the AM60 magnesium alloy. The wear property and the high temperature creep property of the AM60 magnesium alloy are also improved with Si addition. The wear mechanisms of the AM60 and AM60+1.0wt.%Si alloys are adhesive wear and abrasion wear, respectively. While, the elongation of the AM60 magnesium alloy decreases with the addition of Si. The optimum Si addition content is 1.0wt.%.

Prevention of cognitive impairment in diabetic rats with oral magnesium sulfate

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Gharibzadeh Sh

2007-11-01

Full Text Available Background: Diabetes mellitus is a common metabolic disorder accompanied with structural and functional changes in central and peripheral nervous system. Researches showed, memory disturbance were occurred in the course of diabetes. On the other hand, magnesium deficit has been described in diabetic patients. Some researches were showed that, appropriate magnesium supplementation can play a positive role in diabetic control.Methods: Locally produced male rats were used. Diabetes was induced with intravenous injection of 40 mg/kg streptozotosin. In treatment groups, the animals were received magnesium sulfate via drinking water (10 g/l. Eight weeks after diabetes confirmation, the animals were assessed on Morris Water Maze.Results: A significant decrease in time of platform finding (latency and distance of swimming in all four experimental days were seen in all groups. Mean latency in diabetic group was significantly higher than the other. This weak response was almost completely prevented by magnesium sulfate administration.Conclusion: It seems that after eight weeks magnesium sulfate administration (10g/l, spatial memory of the animals was improved in comparison to diabetic group that can suggest role of magnesium in recovery of diabetic animal memory.

Applicability of existing magnesium alloys as biomedical implant materials

NARCIS (Netherlands)

Erinc, M.; Sillekens, W.H.; Mannens, R.G.T.M.; Werkhoven, R.J.

2009-01-01

Being biocompatible and biodegradable, magnesium alloys are considered as the new generation biomedical implant materials, such as for stents, bone fixtures, plates and screws. A major drawback is the poor chemical stability of metallic magnesium; it corrodes at a pace that is too high for most

COMPARATIVE EFFECTS OF MONOTHERAPY WITH MAGNESIUM AND COMBINED THERAPY WITH MAGNESIUM AND Β-BLOCKER ON PRIMARY MITRAL VALVE PROLAPSE WITH HEART RHYTHM DISORDERS

Directory of Open Access Journals (Sweden)

E. G. Nurtdinova

2007-01-01

Full Text Available Aim. To compare effects of monotherapy with magnesium and combined therapy with magnesium and β-blocker on primary mitral valve prolapse (MVP with heart rhythm disorders.Material and methods. 71 patients with primary MVP 1-2 degree and heart rhythm disorders were involved in the study. The patients were split into three groups. Group I (25 persons received monotherapy with magnesium orotate at a dose of 1-3 g per day; group II (28 persons received combined therapy with magnesium orotate and betaxolol. The control group (18 persons received no therapy. Initially and after 12 weeks of observation all the patients underwent electrocardiography (ECG, ECG-Holter monitoring, echocardiography and autonomic balance assessment by A.M. Vein’s questionnaire.Results. In 12 weeks of treatment groups I and II showed positive dynamics in the MVP manifestations, including significant reduction in severity of the autonomic dysfunction syndrome, ECG positive dynamics, antiarrhythmic effect, decrease in the degree of prolapse, diminution of mitral regurgitation and left auricle volumes. More substantial hemodynamic effects were found in the group of patients who received combination therapy.Conclusion. Combined therapy has proven advantages in comparison with magnesium monotherapy in terms of daily quantity of extrasystoles, reduction in heart rate, decrease in autonomic disfunction and normalization of intracardiac hemodynamics.

COMPARATIVE EFFECTS OF MONOTHERAPY WITH MAGNESIUM AND COMBINED THERAPY WITH MAGNESIUM AND Β-BLOCKER ON PRIMARY MITRAL VALVE PROLAPSE WITH HEART RHYTHM DISORDERS

Directory of Open Access Journals (Sweden)

E. G. Nurtdinova

2015-12-01

Full Text Available Aim. To compare effects of monotherapy with magnesium and combined therapy with magnesium and β-blocker on primary mitral valve prolapse (MVP with heart rhythm disorders.Material and methods. 71 patients with primary MVP 1-2 degree and heart rhythm disorders were involved in the study. The patients were split into three groups. Group I (25 persons received monotherapy with magnesium orotate at a dose of 1-3 g per day; group II (28 persons received combined therapy with magnesium orotate and betaxolol. The control group (18 persons received no therapy. Initially and after 12 weeks of observation all the patients underwent electrocardiography (ECG, ECG-Holter monitoring, echocardiography and autonomic balance assessment by A.M. Vein’s questionnaire.Results. In 12 weeks of treatment groups I and II showed positive dynamics in the MVP manifestations, including significant reduction in severity of the autonomic dysfunction syndrome, ECG positive dynamics, antiarrhythmic effect, decrease in the degree of prolapse, diminution of mitral regurgitation and left auricle volumes. More substantial hemodynamic effects were found in the group of patients who received combination therapy.Conclusion. Combined therapy has proven advantages in comparison with magnesium monotherapy in terms of daily quantity of extrasystoles, reduction in heart rate, decrease in autonomic disfunction and normalization of intracardiac hemodynamics.

Extractive process for preparing high purity magnesium chloride hexahydrate

Directory of Open Access Journals (Sweden)

Fezei Radouanne

2012-01-01

Full Text Available This paper refers a method for the preparation of magnesium chloride hexahydrate (bischofite from Sebkha el Melah of Zarzis Tunisian natural brine. It is a five-stage process essentially based on crystallization by isothermal evaporation and chemical precipitation. The two first steps were dedicated to the crystallization of sodium chloride and potassiummagnesium double salts, respectively. Then, the resulting liquor was desulfated using calcium chloride solution. After that another isothermal evaporation stage was implemented in order to eliminate potassium ions in the form of carnallite, KCl.MgCl2.6H2O. At the end of this step, the recovered solution primarily composed of magnesium and chloride ions was treated by dioxan in order to precipitate magnesium chloride as MgCl2.6H2O.C4H8O2. This compound dried at constant temperature of 100°C gave good quality magnesium chloride hexahydrate. Besides this salt, the various by-products obtained from the different treatment stages are also useful.

Experimental and numerical analyses of magnesium alloy hot workability

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F. Abbassi

2016-12-01

Full Text Available Due to their hexagonal crystal structure, magnesium alloys have relatively low workability at room temperature. In this study, the hot workability behavior of cast-extruded AZ31B magnesium alloy is studied through hot compression testing, numerical modeling and microstructural analyses. Hot deformation tests are performed at temperatures of 250 °C to 400 °C under strain rates of 0.01 to 1.0 s−1. Transmission electron microscopy is used to reveal the presence of dynamic recrystallization (DRX, dynamic recovery (DRY, cracks and shear bands. To predict plastic instabilities during hot compression tests of AZ31B magnesium alloy, the authors use Johnson–Cook damage model in a 3D finite element simulation. The optimal hot workability of magnesium alloy is found at a temperature (T of 400 °C and strain rate (ε˙ of 0.01 s−1. Stability is found at a lower strain rate, and instability is found at a higher strain rate.

Solidification of aqueous radioactive waste using insoluble compounds of magnesium oxide

International Nuclear Information System (INIS)

Carlson, J.E.

1986-01-01

A process is described for the treatment of radioactive waste which comprises: (a) first adding, under continuous agitation, a sufficient amount of a powdered magnesium oxide or magnesium hydroxide to an aqueous radioactive waste solution containing boric acid, the temperature of the water solution being 55-95 degrees C. to produce a magnesium borate derivative; (b) adding cement, under continuous agitation, to the magnesium borate derivative; and (c) then adding, under continuous agitation, after the cement has been dispersed, a sufficient amount of a compound selected from the group consisting of calcium oxide and calcium hydroxide to (b) to produce a gel matrix structure

Magnesium and the Risk of Cardiovascular Events: A Meta-Analysis of Prospective Cohort Studies

Science.gov (United States)

Hao, Yongqiang; Li, Huiwu; Tang, Tingting; Wang, Hao; Yan, Weili; Dai, Kerong

2013-01-01

Background Prospective studies that have examined the association between dietary magnesium intake and serum magnesium concentrations and the risk of cardiovascular disease (CVD) events have reported conflicting findings. We undertook a meta-analysis to evaluate the association between dietary magnesium intake and serum magnesium concentrations and the risk of total CVD events. Methodology/Principal Findings We performed systematic searches on MEDLINE, EMBASE, and OVID up to February 1, 2012 without limits. Categorical, linear, and nonlinear, dose-response, heterogeneity, publication bias, subgroup, and meta-regression analysis were performed. The analysis included 532,979 participants from 19 studies (11 studies on dietary magnesium intake, 6 studies on serum magnesium concentrations, and 2 studies on both) with 19,926 CVD events. The pooled relative risks of total CVD events for the highest vs. lowest category of dietary magnesium intake and serum magnesium concentrations were 0.85 (95% confidence interval 0.78 to 0.92) and 0.77 (0.66 to 0.87), respectively. In linear dose-response analysis, only serum magnesium concentrations ranging from 1.44 to 1.8 mEq/L were significantly associated with total CVD events risk (0.91, 0.85 to 0.97) per 0.1 mEq/L (Pnonlinearity = 0.465). However, significant inverse associations emerged in nonlinear models for dietary magnesium intake (Pnonlinearity = 0.024). The greatest risk reduction occurred when intake increased from 150 to 400 mg/d. There was no evidence of publication bias. Conclusions/Significance There is a statistically significant nonlinear inverse association between dietary magnesium intake and total CVD events risk. Serum magnesium concentrations are linearly and inversely associated with the risk of total CVD events. PMID:23520480

The Importance of Magnesium in the Human Body: A Systematic Literature Review.

Science.gov (United States)

Glasdam, Sidsel-Marie; Glasdam, Stinne; Peters, Günther H

2016-01-01

Magnesium, the second and fourth most abundant cation in the intracellular compartment and whole body, respectively, is of great physiologic importance. Magnesium exists as bound and free ionized forms depending on temperature, pH, ionic strength, and competing ions. Free magnesium participates in many biochemical processes and is most commonly measured by ion-selective electrode. This analytical approach is problematic because complete selectivity is not possible due to competition with other ions, i.e., calcium, and pH interference. Unfortunately, many studies have focused on measurement of total magnesium rather than its free bioactive form making it difficult to correlate to disease states. This systematic literature review presents current analytical challenges in obtaining accurate and reproducible test results for magnesium. © 2016 Elsevier Inc. All rights reserved.

Corrosion resistance of zinc-magnesium coated steel

International Nuclear Information System (INIS)

Hosking, N.C.; Stroem, M.A.; Shipway, P.H.; Rudd, C.D.

2007-01-01

A significant body of work exists in the literature concerning the corrosion behaviour of zinc-magnesium coated steel (ZMG), describing its enhanced corrosion resistance when compared to conventional zinc-coated steel. This paper begins with a review of the literature and identifies key themes in the reported mechanisms for the attractive properties of this material. This is followed by an experimental programme where ZMG was subjected to an automotive laboratory corrosion test using acidified NaCl solution. A 3-fold increase in time to red rust compared to conventional zinc coatings was measured. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the corrosion products formed. The corrosion products detected on ZMG included simonkolleite (Zn 5 Cl 2 (OH) 8 . H 2 O), possibly modified by magnesium uptake, magnesium hydroxide (Mg(OH) 2 ) and a hydroxy carbonate species. It is proposed that the oxygen reduction activity at the (zinc) cathodes is reduced by precipitation of alkali-resistant Mg(OH) 2 , which is gradually converted to more soluble hydroxy carbonates by uptake of atmospheric carbon dioxide. This lowers the surface pH sufficiently to allow thermodynamically for general precipitation of insoluble simonkolleite over the corroding surface thereby retarding the overall corrosion reactions, leaving only small traces of magnesium corrosion products behind. Such a mechanism is consistent with the experimental findings reported in the literature

New ternary tantalum borides containing boron dumbbells: Experimental and theoretical studies of Ta{sub 2}OsB{sub 2} and TaRuB

Energy Technology Data Exchange (ETDEWEB)

Mbarki, Mohammed; Touzani, Rachid St.; Rehorn, Christian W.G.; Gladisch, Fabian C. [Institute of Inorganic Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Fokwa, Boniface P.T., E-mail: bfokwa@ucr.edu [Institute of Inorganic Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Department of Chemistry, University of California Riverside (UCR), Riverside, CA 92521 (United States)

2016-10-15

The new ternary transition metal-rich borides Ta{sub 2}OsB{sub 2} and TaRuB have been successfully synthesized by arc-melting the elements in a water-cooled crucible under an argon atmosphere. The crystal structures of both compounds were solved by single-crystal X-ray diffraction and their metal compositions were confirmed by EDX analysis. It was found that Ta{sub 2}OsB{sub 2} and TaRuB crystallize in the tetragonal Nb{sub 2}OsB{sub 2} (space group P4/mnc, no. 128) and the orthorhombic NbRuB (space group Pmma, no. 51) structure types with lattice parameters a=5.878(2) Å, c=6.857(2) Å and a=10.806(2) Å, b=3.196(1) Å, c=6.312(2) Å, respectively. Furthermore, crystallographic, electronic and bonding characteristics have been studied by density functional theory (DFT). Electronic structure relaxation has confirmed the crystallographic parameters while COHP bonding analysis indicates that B{sub 2}-dummbells are the strongest bonds in both compounds. Moreover, the formation of osmium dumbbells in Ta{sub 2}OsB{sub 2} through a Peierls distortion along the c-axis, is found to be the origin of superstructure formation. Magnetic susceptibility measurements reveal that the two phases are Pauli paramagnets, thus confirming the theoretical DOS prediction of metallic character. Also hints of superconductivity are found in the two phases, however lack of single phase samples has prevented confirmation. Furthermore, the thermodynamic stability of the two modifications of AMB (A=Nb, Ta; M =Ru, Os) are studied using DFT, as new possible phases containing either B{sub 4}- or B{sub 2}-units are predicted, the former being the most thermodynamically stable modification. - Graphical abstract: The two new ternary tantalum borides, Ta{sub 2}OsB{sub 2} and TaRuB, have been discovered. Their crystal structures contain boron dumbbells, which are the strongest bonds. Peirls distortion is found responsible for Os{sub 2}-dumbbells formation in Ta{sub 2}OsB{sub 2}. Ta{sub 2}OsB{sub 2} and

Clinical significance of low serum magnesium in pregnant women ...

African Journals Online (AJOL)

Objective: Magnesium level is known to decline during pregnancy. A suggested role for magnesium deficiency in conditions like pre‑eclampsia and pre‑term birth has prompted studies with conflicting evidence. The primary objective of this study was to determine the prevalence of hypomagnesemia in pregnancy, while the ...

Influence of Magnesium Alloy Degradation on Undifferentiated Human Cells.

Science.gov (United States)

Cecchinato, Francesca; Agha, Nezha Ahmad; Martinez-Sanchez, Adela Helvia; Luthringer, Berengere Julie Christine; Feyerabend, Frank; Jimbo, Ryo; Willumeit-Römer, Regine; Wennerberg, Ann

2015-01-01

Magnesium alloys are of particular interest in medical science since they provide compatible mechanical properties with those of the cortical bone and, depending on the alloying elements, they have the capability to tailor the degradation rate in physiological conditions, providing alternative bioresorbable materials for bone applications. The present study investigates the in vitro short-term response of human undifferentiated cells on three magnesium alloys and high-purity magnesium (Mg). The degradation parameters of magnesium-silver (Mg2Ag), magnesium-gadolinium (Mg10Gd) and magnesium-rare-earth (Mg4Y3RE) alloys were analysed after 1, 2, and 3 days of incubation in cell culture medium under cell culture condition. Changes in cell viability and cell adhesion were evaluated by culturing human umbilical cord perivascular cells on corroded Mg materials to examine how the degradation influences the cellular development. The pH and osmolality of the medium increased with increasing degradation rate and it was found to be most pronounced for Mg4Y3RE alloy. The biological observations showed that HUCPV exhibited a more homogeneous cell growth on Mg alloys compared to high-purity Mg, where they showed a clustered morphology. Moreover, cells exhibited a slightly higher density on Mg2Ag and Mg10Gd in comparison to Mg4Y3RE, due to the lower alkalinisation and osmolality of the incubation medium. However, cells grown on Mg10Gd and Mg4Y3RE generated more developed and healthy cellular structures that allowed them to better adhere to the surface. This can be attributable to a more stable and homogeneous degradation of the outer surface with respect to the incubation time.

Magnesium Repair by Cold Spray

National Research Council Canada - National Science Library

Champagne, V. K; Leyman, P.F; Helfritch, D. J

2008-01-01

.... Army Research Laboratory has developed a cold spray process to reclaim magnesium components that shows significant improvement over existing methods and is in the process of qualification for use on rotorcraft...

Mechanical Properties of Magnesium-Rare Earth Alloy Systems: A Review

Directory of Open Access Journals (Sweden)

Sravya Tekumalla

2014-12-01

Full Text Available Magnesium-rare earth based alloys are increasingly being investigated due to the formation of highly stable strengthening phases, activation of additional deformation modes and improvement in mechanical properties. Several investigations have been done to study the effect of rare earths when they are alloyed to pure magnesium and other Mg alloys. In this review, the mechanical properties of the previously investigated different magnesium-rare earth based binary alloys, ternary alloys and other higher alloys with more than three alloying elements are presented.

Effects of magnesium sulfate on the foliar absorption of phosphates at the pumpkin; Effets du sulfate de magnesium sur l'absorption foliaire de phosphates chez le potiron

Energy Technology Data Exchange (ETDEWEB)

Chamel, A

1962-07-01

The foliar absorption of phosphates labelled with {sup 32}P and applied with or without magnesium sulfate on the first leaf of pumpkin seedlings have been studied. The magnesium sulfate applied with the phosphate reduces plainly the absorption rate of {sup 32}P. (O.M.) [French] Nous avons etudie l'absorption foliaire de phosphates marques au {sup 32}P appliques, avec et sans sulfate de magnesium, sur la premiere feuille de jeunes plants de potirons. Le sulfate de magnesium applique avec le phosphate diminue nettement le taux d'absorption du {sup 32}P. (auteur)

Studies on the extraction of nuclear pure magnesium from sea bittern

International Nuclear Information System (INIS)

Isaack, S.L.

1979-01-01

This investigation is devoted to the extraction of nuclear grade magnesium from sea bittern. It comprises three main parts: The first is pertaining to examine the effect of bittern evaporation on both its physical and chemical properties. It a second part , a brief comparative study on magnesium extraction from bittern by use of lime, dolime, solvent extraction and precipitation with ammonia solution and gas as also with ammonia carbon dioxide gas mixture, has been attempted. The precipitation approach by ammonia-carbon dioxide mixture was the mean adopted. A careful systematic examination of various parameters affecting precipitation was undertaken on economic basis. Recovery and purity of magnesium hydroxide, have been taken into account by the study of magnesium concentration in the bittern, its temperature, flow rate of precipitant, ... etc. Since the produced magnesium compound contained 100 ppm of boron, it has to be minimized to less than 1 ppm to agree with the nuclear specifications

Application of magnesium hydroxide and barium hydroxide for the ...

African Journals Online (AJOL)

Application of magnesium hydroxide and barium hydroxide for the removal of metals and sulphate from mine water. ... equivalent to the Ba(OH)2 dosage. During CO2-dosing, CaCO3 is precipitated to the saturation level of CaCO3. Keywords: Magnesium hydroxide; barium hydroxide; sulphate removal; water treatment ...

Efficient One-Step Electrolytic Recycling of Low-Grade and Post-Consumer Magnesium Scrap

Energy Technology Data Exchange (ETDEWEB)

Adam C. Powell, IV

2012-07-19

Metal Oxygen Separation Technologies, Inc. (abbreviated MOxST, pronounced most) and Boston University (BU) have developed a new low-cost process for recycling post-consumer co-mingled and heavily-oxidized magnesium scrap, and discovered a new chemical mechanism for magnesium separations in the process. The new process, designated MagReGenTM, is very effective in laboratory experiments, and on scale-up promises to be the lowest-cost lowest-energy lowest-impact method for separating magnesium metal from aluminum while recovering oxidized magnesium. MagReGenTM uses as little as one-eighth as much energy as today's methods for recycling magnesium metal from comingled scrap. As such, this technology could play a vital role in recycling automotive non-ferrous metals, particularly as motor vehicle magnesium/aluminum ratios increase in order to reduce vehicle weight and increase efficiency.

The Effect of Magnesium Supplementation on Primary Insomnia in the Elderly

Directory of Open Access Journals (Sweden)

Behnood Abbasi

2012-12-01

Full Text Available Background and Aim: Nearly 50% of the elderly have insomnia, with difficulty in going to sleep, oversleeping, or feeling unrefreshed on waking up. With aging, several changes can occur that place one at risk of insomnia. The objective of the present study was to determine the efficacy of magnesium supplementation -the natural NMDA antagonist and GABA agonist- to improve insomnia in the elderly. Materials and Methods: A double blind randomized clinical trial was conducted on 46 elderly subjects, randomly allocated into the magnesium and the placebo group and received 500 mg magnesium and placebos daily for 8 weeks, respectively. Questionnaires of insomnia severity index, physical activity, and sleep-log were completed at baseline and after the intervention period. Anthropometric and dietary confounding factors were obtained using 24h recall for 3 days. Blood samples were taken at baseline and after the intervention period for analysis of serum magnesium, renin, melatonin, and cortisol. Statistical analyses were performed using SPSS (V. 19 and N4 software P-value<0.05 was considered as statistically significant. Results: No significant differences were observed in assessed variables between the two groups at the baseline. According to the present research magnesium supplementation significantly increased sleep time (P=0.002, sleep efficiency (P=0.03, concentration of serum renin (P<0.001 and melatonin (P=0.007 besides, it significantly decreased ISI score (P=0.006, sleep onset latency (P=0.02, and serum cortisol concentration increase (P=0.008 in the magnesium group. Although total sleep time (P=0.37 , waking up length of time (P=0.08, and serum magnesium concentration P=0.06 did not reveal any significant difference. Conclusion: Supplementation of magnesium appears to improve different measures effective in insomnia in the elderly.

Development of biodegradable magnesium alloy stents with coating

Directory of Open Access Journals (Sweden)

Lorenza Petrini

2014-07-01

Full Text Available Biodegradable stents are attracting the attention of many researchers in biomedical and materials research fields since they can absolve their specific function for the expected period of time and then gradually disappear. This feature allows avoiding the risk of long-term complications such as restenosis or mechanical instability of the device when the vessel grows in size in pediatric patients. Up to now biodegradable stents made of polymers or magnesium alloys have been proposed. However, both the solutions have limitations. The polymers have low mechanical properties, which lead to devices that cannot withstand the natural contraction of the blood vessel: the restenosis appears just after the implant, and can be ascribed to the compliance of the stent. The magnesium alloys have much higher mechanical properties, but they dissolve too fast in the human body. In this work we present some results of an ongoing study aiming to the development of biodegradable stents made of a magnesium alloy that is coated with a polymer having a high corrosion resistance. The mechanical action on the blood vessel is given by the magnesium stent for the desired period, being the stent protected against fast corrosion by the coating. The coating will dissolve in a longer term, thus delaying the exposition of the magnesium stent to the corrosive environment. We dealt with the problem exploiting the potentialities of a combined approach of experimental and computational methods (both standard and ad-hoc developed for designing magnesium alloy, coating and scaffold geometry from different points of views. Our study required the following steps: i selection of a Mg alloy suitable for stent production, having sufficient strength and elongation capability; ii computational optimization of the stent geometry to minimize stress and strain after stent deployment, improve scaffolding ability and corrosion resistance; iii development of a numerical model for studying stent

Magnesium intake and colorectal tumor risk: a case-control study and meta-analysis.

NARCIS (Netherlands)

Wark, P.A.; Lau, R.; Norat, T.; Kampman, E.

2012-01-01

BACKGROUND: Dietary magnesium might be related to colorectal tumor risk through the pivotal roles of magnesium in cellular metabolism, insulin resistance, and systemic inflammation. OBJECTIVE: We evaluated the hypothesis of whether higher dietary magnesium intake is associated with reduced

Magnesium intake and colorectal tumor risk : a case-control study and meta-analysis

NARCIS (Netherlands)

Wark, P.A.; Lau, R.; Norat, T.; Kampman, E.

2012-01-01

Background: Dietary magnesium might be related to colorectal tumor risk through the pivotal roles of magnesium in cellular metabolism, insulin resistance, and systemic inflammation. Objective: We evaluated the hypothesis of whether higher dietary magnesium intake is associated with reduced

Magnesium-molybdenum compounds as matrixes of 99m Tc generators

International Nuclear Information System (INIS)

Jimenez M, T.S.

2005-01-01

In order to finding new production alternatives of 99 Mo/ 99m Tc generators, easy to produce and with high elutriation efficiencies, it is proposed in this work to develop a generator with basis of magnesium and molybdenum that could be irradiated after their synthesis, given the short half life of the only radioisotope produced by the magnesium: 27 Mg (t 1/2 = 9.46 m). It is necessary to mention that have not been reported works in relation to this type of compound, being then important to carry out basic studies on the formation and behavior of these in relation to their matrix functions of those generated of 99 Mo/ 99m Tc. In this work it was determined the effect that has, the magnesium salt used in the synthesis of those molybdenum-magnesium compounds, the molar ratio Mo: Mg, the concentration of the magnesium salt, the pH of the used ammonium molybdates in the synthesis of the final compounds and the washing of the molybdates of synthesized magnesium, in the performance of the 99 Mo/ 99m Tc generators. Parameters like the elutriation efficiency, the radionuclide purity, radiochemical and chemical of the eluates and their pH, were determined in each case, also its were characterized the synthesized compounds using: neutron activation analysis (NAA), X-ray diffraction (XRD) and scanning electron microscopy of high vacuum (SEM), besides of complementary techniques: infrared spectroscopy (IR), and thermal gravimetric analysis (TGA). (Author)

Behavior of the ion Magnesium in triathlon half-ironman competition

Directory of Open Access Journals (Sweden)

M. Bürger-Mendonça

2008-01-01

Full Text Available The present study it had as objective to analyze the response of the ion magnesium before and after-competition of triathlon in athlete of the masculine sex, in the half-ironman distance, through it biochemistry analyzes of the concentration of the ion magnesium in the plasma blood. Ten physically active volunteers of the masculine sex participated in the present study, divided in two groups: control and experimental. The integrants of the experimental group was submitted to two blood collections (approximately 25 ml, after eight hours dietary restriction in the seated position. The second blood sample was collected immediately at ending of the competition of each athlete (t=1. For statistical analysis was used the software SPSS 11.0, and T-student test for statistical comparisons between the two groups (P<0.05 accepted as significant. When compared the values before the competition between the control group and experimental group a significant difference in the concentration of plasma magnesium (P=0,005 was observed. When compared the values of plasma magnesium concentration in the experimental group before and after competition a significant difference (P=0,005, with an average reduction of 35,23% was observed. In the comparison of values after-competition between the experimental group and control, a significant difference in the plasma magnesium concentration was detected, indicating that the exercises of long duration cause a depletion of magnesium reserves of the organism.

Behavior of the ion magnesium in triathlon half-ironman competition

Directory of Open Access Journals (Sweden)

Marcos Bürger-Mendonça

2008-06-01

Full Text Available The present study it had as objective to analyze the response of the ion magnesium before and after-competition of triathlon in athlete of the masculine sex, in the half-ironman distance, through it biochemistry analyzes of the concentration of the ion magnesium in the plasma blood. Ten physically active volunteers of the masculine sex participated in the present study, divided in two groups: control and experimental. The integrants of the experimental group was submitted to two blood collections (approximately 25 ml, after eight hours dietary restriction in the seated position. The second blood sample was collected immediately at ending of the competition of each athlete (t=1. For statistical analysis was used the software SPSS 11.0, and T-student test for statistical comparisons between the two groups (P<0.05 accepted as significant. When compared the values before the competition between the control group and experimental group a significant difference in the concentration of plasma magnesium (P=0,005 was observed. When compared the values of plasma magnesium concentration in the experimental group before and after competition a significant difference (P=0,005, with an average reduction of 35,23% was observed. In the comparison of values after-competition between the experimental group and control, a significant difference in the plasma magnesium concentration was detected, indicating that the exercises of long duration cause a depletion of magnesium reserves of the organism.

Magnesium ferrite nanoparticles: a rapid gas sensor for alcohol

Science.gov (United States)

Godbole, Rhushikesh; Rao, Pratibha; Bhagwat, Sunita

2017-02-01

Highly porous spinel MgFe2O4 nanoparticles with a high specific surface area have been successfully synthesized by a sintering free auto-combustion technique and characterized for their structural and surface morphological properties using XRD, BET, TEM and SEM techniques. Their sensing properties to alcohol vapors viz. ethanol and methanol were investigated. The site occupation of metal ions was investigated by VSM. The as-synthesized sample shows the formation of sponge-like porous material which is necessary for gas adsorption. The gas sensing characteristics were obtained by measuring the gas response as a function of operating temperature, concentration of the gas, and the response-recovery time. The response of magnesium ferrite to ethanol and methanol vapors was compared and it was revealed that magnesium ferrite is more sensitive and selective to ethanol vapor. The sensor operates at a substantially low vapor concentration of about 1 ppm of alcohol vapors, exhibits fantastic response reproducibility, long term reliability and a very fast response and recovery property. Thus the present study explored the possibility of making rapidly responding alcohol vapor sensor based on magnesium ferrite. The sensing mechanism has been discussed in co-relation with magnetic and morphological properties. The role of occupancy of Mg2+ ions in magnesium ferrite on its gas sensing properties has also been studied and is found to influence the response of magnesium ferrite ethanol sensor.

Role of Magnesium in Oxidative Stress in Individuals with Obesity.

Science.gov (United States)

Morais, Jennifer Beatriz Silva; Severo, Juliana Soares; Santos, Loanne Rocha Dos; de Sousa Melo, Stéfany Rodrigues; de Oliveira Santos, Raisa; de Oliveira, Ana Raquel Soares; Cruz, Kyria Jayanne Clímaco; do Nascimento Marreiro, Dilina

2017-03-01

Adipose tissue is considered an endocrine organ that promotes excessive production of reactive oxygen species when in excess, thus contributing to lipid peroxidation. Magnesium deficiency contributes to the development of oxidative stress in obese individuals, as this mineral plays a role as an antioxidant, participates as a cofactor of several enzymes, maintains cell membrane stability and mitigates the effects of oxidative stress. The objective of this review is to bring together updated information on the participation of magnesium in the oxidative stress present in obesity. We conducted a search of articles published in the PubMed, SciELO and LILACS databases, using the keywords 'magnesium', 'oxidative stress', 'malondialdehyde', 'superoxide dismutase', 'glutathione peroxidase', 'reactive oxygen species', 'inflammation' and 'obesity'. The studies show that obese subjects have low serum concentrations of magnesium, as well as high concentrations of oxidative stress marker in these individuals. Furthermore, it is evident that the adequate intake of magnesium contributes to its appropriate homeostasis in the body. Thus, this review of current research can help define the need for intervention with supplementation of this mineral for the prevention and treatment of disorders associated with this chronic disease.

A magnesium-induced triplex pre-organizes the SAM-II riboswitch.

Directory of Open Access Journals (Sweden)

Susmita Roy

2017-03-01

Full Text Available Our 13C- and 1H-chemical exchange saturation transfer (CEST experiments previously revealed a dynamic exchange between partially closed and open conformations of the SAM-II riboswitch in the absence of ligand. Here, all-atom structure-based molecular simulations, with the electrostatic effects of Manning counter-ion condensation and explicit magnesium ions are employed to calculate the folding free energy landscape of the SAM-II riboswitch. We use this analysis to predict that magnesium ions remodel the landscape, shifting the equilibrium away from the extended, partially unfolded state towards a compact, pre-organized conformation that resembles the ligand-bound state. Our CEST and SAXS experiments, at different magnesium ion concentrations, quantitatively confirm our simulation results, demonstrating that magnesium ions induce collapse and pre-organization. Agreement between theory and experiment bolsters microscopic interpretation of our simulations, which shows that triplex formation between helix P2b and loop L1 is highly sensitive to magnesium and plays a key role in pre-organization. Pre-organization of the SAM-II riboswitch allows rapid detection of ligand with high selectivity, which is important for biological function.

Grain refinement of AZ31 magnesium alloy by electromagnetic ...

Indian Academy of Sciences (India)

Low-frequency electromagnetic field; AZ31 magnesium alloy; Al4C3; grain refinement. Abstract. The effects of electromagnetic stirring and Al4C3 grain refiner on the grain refinement of semicontinuously cast AZ31 magnesium alloy were discussed in this investigation. The results indicate that electromagnetic stirring has an ...

A comparison of corrosion inhibition of magnesium aluminum and zinc aluminum vanadate intercalated layered double hydroxides on magnesium alloys

Science.gov (United States)

Guo, Lian; Zhang, Fen; Lu, Jun-Cai; Zeng, Rong-Chang; Li, Shuo-Qi; Song, Liang; Zeng, Jian-Min

2018-04-01

The magnesium aluminum and zinc aluminum layered double hydroxides intercalated with NO3 -(MgAl-NO3-LDH and ZnAl-NO3-LDH) were prepared by the coprecipitation method, and the magnesium aluminum and the zinc aluminum layered double hydroxides intercalated with VO x -(MgAl-VO x -LDH and ZnAl-VO x -LDH) were prepared by the anion-exchange method. Morphologies, microstructures and chemical compositions of LDHs were investigated by SEM, EDS, XRD, FTIR, Raman and TG analyses. The immersion tests were carried to determine the corrosion inhibition properties of MgAl-VO x -LDH and ZnAl-VO x -LDH on AZ31 Mg alloys. The results showed that ZnAl-VO x -LDH possesses the best anion-exchange and inhibition abilities. The influence of treatment parameters on microstructures of LDHs were discussed. Additionally, an inhibition mechanism for ZnAl-VO x -LDH on the AZ31 magnesium alloy was proposed and discussed.

Barium titanate coated with magnesium titanate via fused salt method and its dielectric property

International Nuclear Information System (INIS)

Chen Renzheng; Cui Aili; Wang Xiaohui; Li Longtu

2003-01-01

Barium titanate fine particles were coated homogeneously with magnesium titanate via the fused salt method. The thickness of the magnesium titanate film is 20 nm, as verified by TEM and XRD. The mechanism of the coating is that: when magnesium chloride is liquated in 800 deg. C, magnesium will replace barium in barium titanate, and form magnesium titanate film on the surface of barium titanate particles. Ceramics sintered from the coated particles show improved high frequency ability. The dielectric constant is about 130 at the frequency from 1 to 800 MHz

Influence of Magnesium Alloy Degradation on Undifferentiated Human Cells.

Directory of Open Access Journals (Sweden)

Francesca Cecchinato

Full Text Available Magnesium alloys are of particular interest in medical science since they provide compatible mechanical properties with those of the cortical bone and, depending on the alloying elements, they have the capability to tailor the degradation rate in physiological conditions, providing alternative bioresorbable materials for bone applications. The present study investigates the in vitro short-term response of human undifferentiated cells on three magnesium alloys and high-purity magnesium (Mg.The degradation parameters of magnesium-silver (Mg2Ag, magnesium-gadolinium (Mg10Gd and magnesium-rare-earth (Mg4Y3RE alloys were analysed after 1, 2, and 3 days of incubation in cell culture medium under cell culture condition. Changes in cell viability and cell adhesion were evaluated by culturing human umbilical cord perivascular cells on corroded Mg materials to examine how the degradation influences the cellular development.The pH and osmolality of the medium increased with increasing degradation rate and it was found to be most pronounced for Mg4Y3RE alloy. The biological observations showed that HUCPV exhibited a more homogeneous cell growth on Mg alloys compared to high-purity Mg, where they showed a clustered morphology. Moreover, cells exhibited a slightly higher density on Mg2Ag and Mg10Gd in comparison to Mg4Y3RE, due to the lower alkalinisation and osmolality of the incubation medium. However, cells grown on Mg10Gd and Mg4Y3RE generated more developed and healthy cellular structures that allowed them to better adhere to the surface. This can be attributable to a more stable and homogeneous degradation of the outer surface with respect to the incubation time.

Hydrogenation properties of pure magnesium and magnesium-aluminium thin films

Energy Technology Data Exchange (ETDEWEB)

Domenech-Ferrer, Roger; Gurusamy Sridharan, Madana; Garcia, Gemma; Pi, Francesc; Rodriguez-Viejo, Javier [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)

2007-06-10

We have studied the hydrogenation/dehydrogenation behaviour of multilayered stacks of Pd/Mg/Pd and Pd-Fe(Ti)-Mg-Al-Mg-Fe(Ti)-Pd grown by electron beam physical vapour deposition. The palladium coating was deposited at both sides of the structure to ensure a fast dissociation rate and good transport properties for hydrogen as well as to avoid oxidation of magnesium either from atmosphere as from the substrate surface. Fe and Ti layers were included in the stack composition in order to assess their possible catalyst effect as well as to prevent the formation of Mg{sub x}Pd{sub y} intermetallics during the thermal treatments. We have studied the structure evolution after thermal treatments as well as after the hydrogenation and dehydrogenation processes using XRD. We have also followed the reactions kinetics by resistometry and differential scanning calorimetry. The nanostructured Mg films have been hydrogenated at temperature as low as 50 C in few minutes. Adding aluminium to magnesium has improved its hydrogenation capacity. We have also observed that the formation of an Mg{sub x}Al{sub y} intermetallic before hydrogenation improves the storage capacity. We have confirmed that titanium is a better catalyst for the hydrogenation/dehydrogenation of the Mg films. (author)

Magnesium analysis. Determination of 5 elements by impulse polarography

International Nuclear Information System (INIS)

Anon.

Determination of cadmium, copper, nickel, lead and zinc in magnesium used in magnesiothermics. The process is as follow: magnesium dissolution in hydrochloric acid, neutralisation by ammonia, addition of ammonium chloride and citric acid, ammonia is added until pH8. Addition of pyridine, polarographic determination of zinc and then of cadmium and copper [fr

SERUM magnesium levels as an indicator of status of Diabetes Mellitus type 2.

Science.gov (United States)

Ramadass, S; Basu, Sharbari; Srinivasan, A R

2015-01-01

Magnesium deficiency is commonly associated with endocrine and metabolic disorders, especially with Diabetes Mellitus type 2 though the mechanism of hypomagnesemia in Diabetes Mellitus is not completely known. There is a close association between metabolic control of Diabetes Mellitus and impaired magnesium balance. To estimate the serum levels of magnesium in patients of with Diabetes Mellitus type 2 and to find a correlation if any, with the duration and control (by estimating HbA1c) of Diabetes Mellitus type 2. Fifty patients of Diabetes Mellitus type 2 were included in the study. Blood samples were analyzed for fasting and post prandial glucose, HbA1c and magnesium. The patients were grouped into three categories based upon their HbA1c levels into those with good control, need intervention and poor control. The three groups were compared with reference to their mean levels of blood glucose and magnesium. Association of serum magnesium levels with HbA1c, Fasting and postprandial blood glucose and duration of Diabetes Mellitus was also done. Serum magnesium levels were found to decline with rise in HbA1c levels and with duration of Diabetes Mellitus type 2. Hypomagnesemia is linked to poor control of Diabetes Mellitus type 2 and depletion of serum magnesium occurs exponentially with duration of disease. Copyright © 2014 Diabetes India. Published by Elsevier Ltd. All rights reserved.

Magnesium - distribution and basic metabolism

African Journals Online (AJOL)