Search results for "MAGNESIUM"
showing 10 items of 490 documents
Structural properties of magnesium stearate pseudopolymorphs: effect of temperature.
2003
A thorough review of the relevant literature reveals that the interaction between water vapour and magnesium stearate, in contrast to many other metal soaps, is not properly understood. The structural modifications associated with the up-take or loss of water of vegetable-derived commercial magnesium stearate powders exposed to humid air or vacuum at room temperature are investigated using standard powder X-ray diffractometry. It is found that in such conditions magnesium stearate reacts reversibly with the vapour phase with structural consequences very similar to the high temperature transition between the crystalline and rotator phases of other anhydrous metal soaps. When temperature is i…
Scanning electron microscopic and X ray microanalysis study of the mineral deposits in pseudoxanthoma elasticum.
1977
A skin biopsy of a 37 year old man with typical lesions of pseudoxanthoma clasticum (P.E.) associated with angioid streaks (Groenblad-Strandberg Syndrom) was examined with a scanning E. M. (SEM) and a SEM provided with a X ray micro-analyser. The SEM provided with X ray microanalyser enabled us to see the correspondence between the crystalline deposits and a calcium salt. The potassium, sodium and magnesium analysis of the specimen permits us to verify that the P.E. dermis is rich in K and poor in Mg.
Magnesium Role in Health and Longevity Final
2018
Reduced Magnesium (Mg intake) is a frequent cause of Mg deficit with age. A decreased intestinal Mg absorption and an increased Mg loss may also contribute, as well as the use of medicaments. Mg requirements may be higher with aging. Alterations of Mg metabolism with age, cellular Mg transport systems and problems with measurement methods are discussed. Mg contained in water is more bio-available than Mg in food and it is a possible alternative to Mg supplementation in the correction of Mg deficiencies. Mild to moderate Mg deficits are generally asymptomatic and clinical signs are usually absent or non-specific. Hyperemotionality, tremor, asthenia, sleep disorders, and amnesic and cognitive…
Formability of Friction Stir Welded AZ31 Magnesium Alloy Sheets
2010
The formability of friction stir welded AZ31 magnesium alloy sheets was investigated by means of uniaxial tensile and hemispherical punch tests performed under different process conditions. The results of the tensile tests were analysed in terms of flow stress and ductility at different temperature and strain rate; the hemispherical punch tests, carried out at different temperatures, provided the limiting dome height. The formability of FSW-ed blanks was compared to the one exhibited by the base material in order to evaluate the quality of the welded joints.
Magnesium and health outcomes: An umbrella review of systematic reviews and meta-analyses of observational and intervention studies
2020
Purpose: To map and grade all health outcomes associated with magnesium (Mg) intake and supplementation using an umbrella review. Methods: Umbrella review of systematic reviews with meta-analyses of observational studies and randomized controlled trials (RCTs) using placebo/no intervention as control group. We assessed meta-analyses of observational studies based on random-effect summary effect sizes and their p values, 95% prediction intervals, heterogeneity, small-study effects and excess significance. For meta-analyses of RCTs, outcomes with a random-effect p value < 0.005 and a high-GRADE assessment were classified as strong evidence. Results: From 2048 abstracts, 16 meta-analyses an…
On the difficulty of assessing the specific surface area of magnesium stearate
2001
Abstract The water content of as-received commercial magnesium stearate batches from animal and vegetable sources have been modified by ageing in humid air at room temperature or by vacuum treatment. The complete adsorption–desorption isotherms of nitrogen and krypton vapours by samples of these as received and modified materials have been measured at liquid nitrogen temperature after standardised vacuum degassing. They are greatly affected by the initial water content of the material. In particular: (a) the BET surface area values computed from the adsorption branch vary widely and is increasing with increasing water content; (b) anomalous hysteresis of varying amplitude is observed in all…
Surface Flows of Soft Monopole Modes of 40Mg
2018
In order to explore the nature of collective modes in weakly bound nuclei, we have investigated surface flow patterns of isoscalar monopole modes in a shape-coexisting nucleus 40Mg. The calculations were done in a fully self-consistent continuum finite-amplitude-method quasiparticle-random-phase-approximation (FAM-QRPA) in a large deformed spatial mesh. Our results demonstrated that the transition current densities at surfaces are nontrivial and dependent on deformations. The toroidal mode is favorable in the oblate shape, demonstrating the geometric deformation effects on nuclear surface flows. The surface flow patterns become more complicated as excitation energies increase. peerReviewed
All-atom simulations disentangle the functional dynamics underlying gene maturation in the intron lariat spliceosome
2018
The spliceosome (SPL) is a majestic macromolecular machinery composed of five small nuclear RNAs and hundreds of proteins. SPL removes noncoding introns from precursor messenger RNAs (pre-mRNAs) and ligates coding exons, giving rise to functional mRNAs. Building on the first SPL structure solved at near–atomic-level resolution, here we elucidate the functional dynamics of the intron lariat spliceosome (ILS) complex through multi-microsecond-long molecular-dynamics simulations of ∼1,000,000 atoms models. The ILS essential dynamics unveils (i) the leading role of the Spp42 protein, which heads the gene maturation by tuning the motions of distinct SPL components, and (ii) the critical particip…
The effect of excipients on the stability and phase transition rate of xylazine hydrochloride and zopiclone
2015
The compatibility of thermodynamically unstable polymorph of two active pharmaceutical compounds (xylazine hydrochloride form X and zopiclone form C) with different excipients was investigated. The effects of the excipient and its amount in the sample on the thermal properties and possible chemical interactions were studied. The most commonly used excipients in the pharmaceutical industry - calcium carbonate, lactose hydrate, cellulose, magnesium stearate hydrate and calcium stearate hydrate were selected for this study. The dependence of the phase transition rate from an unstable to a more stable polymorph on the excipients and their amounts in the initial sample was analysed at 80°C, and …
Process Mechanics in Friction Stir Welding of Magnesium Alloys: Experimental and Numerical Analysis
2012
Light weight construction is a major task within automotive and aircraft industry due to lower fuel consumption or increase the possible payload. Structural or exterior shell components are more and more manufactured out of aluminum alloys for this reason. A further weight reduction could be achieved by the substitution of aluminum alloys by magnesium alloys. Also the application of blanks with a varying thickness is a possibility to realize light weight design. To combine the advantages of weight reduction by the use of magnesium alloys and tailored welded blanks (TWBs), an effective joining technique is required. Friction Stir Welding can be used for difficult to be welded magnesium alloy…