Weight Of Mg Research Articles

Analysis of the Influence of Organophosphorus Compounds and of Aluminium and Magnesium Hydroxides on Combustion Properties of Epoxy Materials

This paper presents the influence of selected flame retardant additives on heat release rate and thermokinetics properties of epoxy materials made of epoxy resin—Epidian 5. The epoxy resin underwent flame retardant modification with the use of organophosphorus compounds (Roflam F5, Roflam B7) and Al(OH)3, Mg(OH)2. The fire characteristics of the analysed epoxy resin were determined using the cone calorimeter method, and thermal analysis of epoxy resin and the surface morphology of the analysed epoxy materials was with the use of an SEM microscope with an EDS attachment. The lowest value of the heat release rate was recorded for hardened epoxy resin containing one component additive 5% by weight of Mg(OH)2, as well as two component additive 10% by weight of Roflam F5 and 5% by weight of Al(OH)3. Moreover, the initial temperature of thermal decomposition of phase I of the modified epoxy resin samples with Mg(OH)2 (sample 5M) or organophosphorus compounds and Mg(OH)2 (samples 5B + 10M and 5F + 10M) were higher compared to the unmodified epoxy resin for these samples. Considering the surface morphology of the samples with Mg(OH)2, it can be concluded that the additives cause a homogeneous charred layer.

The evolution of saponite: An experimental study based on crystal chemistry and crystal growth

AbstractElement incorporation and partitioning during the evolution of clay minerals have significant implications for element cycling in geochemical processes. The main aim of this experimental study is to further our understanding of element redistribution and crystal growth during smectite evolution under different physicochemical conditions. The precursors (i.e., pure Mg- and Ni-saponite) were separately prepared by hydrothermal syntheses at the same set of temperatures (i.e., RT, 50, 150, 180, 200, and 220 °C) for one day. Then the starting materials were obtained from the mechanical mixtures of the identical molar weight of Mg- and Ni-smectite precursors prepared at the same temperature. Subsequently, Series I samples were obtained by hydrothermally treating different starting materials at 220 °C for two weeks while Series II samples were hydrothermally synthesized under various temperatures (220, 300, 400, and 500 °C) for one week using the starting materials prepared at 220 °C. Both the precursors and resultant saponites were characterized by XRD, FTIR, TEM, and STEM. The FTIR spectra of the precursors only exhibit the vMg3OH and vNi3OH bands, corresponding to Mg-saponite and Ni-saponite, respectively. However, the occurrence of vMg2NiOH and vNi2MgOH bands in the resultant saponite indicates the dissolution of the corresponding Mg- and Ni-saponite precursors and recrystallization of Mg-Ni mixed saponite. The dissolution extents of Mg- and Ni-saponite precursors, which affect the degrees of random distribution of octahedral Ni and Mg in resultant Mg, Nisaponite, are significantly controlled by the temperature gap (ΔT) between the precursors prepared and the resultant Mg, Ni-saponite obtained. In general, a larger ΔT leads to a higher dissolution extent of saponite precursors and a higher degree of random distribution of octahedral Ni and Mg cations in the resultant Mg, Ni-saponite structures. Thus, the distribution mode of octahedral cations in saponite, which is not only relevant to a given hydrothermal temperature but also dependent on ΔT for final products, cannot be used as a geothermometer. TEM and STEM observations provide visual evidence that the particles of saponite coarsen when ΔT is higher than zero. Both the crystal-chemical and morphological features during saponite evolution suggest that saponite particles coarsen mainly via partial/complete dissolution of precursors followed by recrystallization and growth of Mg, Ni-saponite in which crystal growth by layer attachment cannot be excluded. This study presents an experimental approach to evaluate the evolution of clay minerals in terms of crystal chemistry and crystal growth and offers a better understanding of the contributions of clay mineral evolution to element cycling.

Influence of milling energy of in-situ precursor powder on the properties of Ti-doped MgB2

The effect of Ti-doping on the electrical properties of MgB2 bulks was studied in dependence on the milling energy of the used in-situ precursor powder. Ti-powder was added to a mixture of Mg- and B-powder before milling in three different concentrations related to the atomic weight of Mg (Mg1-xTixB2 with x = 0.025/0.05/0.1). From each doping concentration two different powders were milled with a planetary ball mill (for 1 resp. 10 h, rotation speed 250 rpm). This corresponds to a milling energy of 5⋅108 J/kg resp. 5⋅109 J/kg. The electrical resistivity in normal state of the bulk samples is increasing by Ti-doping. The most interesting point is the influence of Ti-doping on the magnetic field dependence of the critical current density jc of samples prepared with powders milled with different energy. A remarkable increase of jc was found with increasing Ti-content at 4.2 K and external fields higher than around 4 T for the powder with lower milling energy. Not any effect could be measured at the powder milled with higher energy. If we take into account that the grain sizes of the samples prepared with higher energy milled powder is remarkably smaller than that of the other sample it can be noticed that Ti-doping has only a distinct effect on the grain size, like discussed in [1], of samples with coarser powder, not on high energy milled powders.

Effect of HF Concentration on Corrosion Resistance of Biomedical Implants

This work compared the variation of weight of Mg 1%Ca as cast in different concentrations of hydrofluoric acid (HF) such as 45% - 40% - 35% - 25% - 20 % - 13% - 7 % for 24 h at room temperature to be utilized in biomaterial application like hip, knee implants that have effect on corrosion resistance. By immersion Mg 1%Ca alloys in HF, the layer of MgF2 was constituted on the surface of alloy and this layer improves the corrosion and causes weight gain. The results show that in order to get a better corrosion resistance, surface treatment should be done in 40% of HF, because the weight gain is more than other HF concentrations.

Elaboration and hydriding behavior characterization of a magnesium matrix composite containing intermetallic particles

The AB2 Laves phase intermetallic compounds, as well as magnesium metal (among a great variety of other metals and alloys) present hydriding properties of interest for practical applications in hydrogen storage devices through the formation of metallic hydrides. This fact has encouraged numerous experimental works concerning the characterization of materials by different available techniques. The application of internal friction measurements to study the hydriding processes of intermetallic compounds is precluded because of the fast decrepitation of the material upon few cycles of formation and decomposition of the hydrid phase. However, a composite where the intermetallic particles are included within a ductile magnesium matrix, is suitable to be studied by internal friction techniques, and possible of obtaining information about the interaction between hydrogen atoms, particles, and matrix. In the present work, it is described the elaboration of a composite material obtained by sintering a pellet prepared from a mixture of equal amounts in weight of Mg and Zr(Fe0.7Cr0.3)2 particles, ranging in sizes up to 250 μm and 50 μm respectively. Details on some experimental procedures and discussion about the material composition are considered and correlated with morphological characteristics determined by SEM, and also assessed from the observed hydriding behavior and internal friction results.

Magnesium Deficiency Induces Bone Loss in the Rat

Disorders in which magnesium (Mg) depletion is common have an associated high incidence of osteoporosis. Mg depletion in humans results in hypocalcemia, low serum parathyroid hormone (PTH) and 1,25(OH)₂-vitamin D levels, as well as PTH and vitamin D resistance which may serve as mechanisms for the development of osteoporosis. In order to determine if isolated Mg depletion will result in bone loss, we have induced dietary Mg deficiency in the rat. Adult (290 g) female rats were given either a low-Mg diet (2 mg/100 g chow; n = 6) or a normal control Mg diet (63 mg/100 g chow; n = 6). Dietary calcium (Ca) was normal in both groups (592 mg/100 g chow). At 12 weeks, blood was obtained for serum Mg, Ca, PTH, 1,25(OH)₂-vitamin D, and osteocalcin determinations. The rats were then euthanized and the femurs obtained for mineral analysis and histomorphometry. Serum Mg in the low-Mg group was less than control (0.4 ± 0.2 vs. 1.9 ± 0.2 mg/dl, p < 0.001; mean ± SD) while serum Ca was higher (11.7 ± 0.5 vs. 9.3 ± 0.4 mg/dl, p < 0.001). PTH was suppressed in the Mg-deficient group (36 ± 16 vs. 109 ± 30 pg/ml in controls, p < 0.002). Serum 1,25(OH)₂-vitamin D was also suppressed in the Mg-deficient animals (7.1 ± 4.8 vs. 28.5 ± 8.2 pg/ml in controls, p < 0.002). Serum osteocalcin levels were not different (19.8 ± 2.5 ng/ml in Mg-deficient rats vs. 15.3 ± 3.4 ng/ml in controls). While the ash weight of Ca and phosphorus in the femur did not change, the ash weight of Mg fell (low-Mg group 0.55 ± 0.01%, controls 0.65 ± 0.02%, p < 0.001). Histomorphometry demonstrated reduction in bone mass; the trabecular bone volume in the femur of the low-Mg group was reduced from control (7.7 ± 0.2 vs. 13.7 ± 1.9%, p < 0.002). A surprising new observation was an increase in osteoclast (OC) bone resorption with Mg depletion. The number of OC per millimeter bone surface was 16.9 ± 1.3 in the low-Mg group versus 7.8 ± 1.5 in controls (p < 0.001). The percentage of bone surface occupied by OC was 38.3 ± 3.7 in the low-Mg group versus 17.7 ± 2.4 in controls (p < 0.001). This increased resorption occurred with an inappropriate non-altered bone-forming surface relative to control (% osteoid surface: low-Mg group 2.4 ± 0.7 vs. controls 2.6 ± 0.4; % osteoid volume: low-Mg group 0.25 ± 0.09 vs. controls 0.38 ± 0.06; number of osteoblasts per millimeter bone surface: low-Mg group 0.9 ± 0.3 vs. controls 1.3 ± 0.3). No increase in bone-forming surface or osteoblast number despite an increase in OC-resorbing surface and OC number strongly suggests impaired activation of osteoblasts and an uncoupling of bone formation and bone resorption. Our data demonstrate that Mg depletion in the rat alters bone and mineral metabolism which results in bone loss.

Chemical Composition of Foliage from Fertilized Plus Douglas Fir Trees and Adjacent Unfertilized Check Trees

AbstractShoots of the 1960, 1961, and 1962 growth were removed from two fertilized plus trees and two unfertilized adjacent check trees in April 1963. Each plus tree received 80 pounds of 16‐20‐0 ammonium phosphate sulphate fertilizer in April 1961, and 40 pounds of the same fertilizer in April 1962. The length of the shoots was measured and needle production was determined. Needles from each of the 3 years of growth were analyzed for N, P, K, Ca, Mg and S.Fertilization increased the length of the 1962 shoots. Diameter of the shoots also appeared to be increased. Needles from the fertilized trees seemed to be larger and darker green in color. Weight of needles produced in 1962 was greatly increased by fertilization. Concentration and weight of N in needles was markedly increased by fertilization, particularly in the 1962 growth. Phosphorus concentration was slightly reduced by fertilization. However, the weight of P in the 1962 needles was increased by fertilization. The N/P ratios in all needle samples from the fertilized trees were much greater than those in the unfertilized check trees. Although K concentration was reduced in the foliage from fertilized trees, weight of K was not influenced by fertilization. Potassium percentage tended to be lowest in the oldest tissue, and highest in the youngest tissue of all trees. Concentration and weight of Ca was highest in foliage from the fertilized trees. Calcium concentration increased with age of all foliage samples. Fertilization resulted in an increase in concentration and weight of Mg. Concentration and weight of S was highest in the foliage from fertilized trees. Older needles appeared to have a higher S concentration than the younger needles.

胎盤絨毛膜ホルモンの化学的研究 (第2報)

Various physical constants were determined of the principle (MG) of the Mainini reaction, isolated from human placenta, as a product of approximately single component according to electrophoretic and ultracentrifugal examinations. From the determination of its mobility rate (Table I and Fig. 2), isoelectric point of MG was found to lie between pH 4.1 and 4.2. Its diffusion constant was D20W=2.53×10-7cm.2/sec. and sedimentation constant, S20W=2.55×10-13(cm./sec.)/(dyne/g.). The molecular weight of MG calculated from these constants is about 100, 000 and about 150, 000 from light scattering analysis. Such a large difference due to the method of determination was assumed to be caused by the high content of sugars. The MG molecule is assumed to take rod form of extremely elongated type, showing friction ratio f/f0=2.68, axial ratio of prolate 29.4-33.3, and oblate 40-55.