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At least 109 records · Page 6Linked to original sources
PubMed1996

Oral physiological magnesium supplementation for 6 weeks with 1 g/d magnesium oxide does not affect increased Lp(a) levels in hypercholesterolaemic subjects.

Twenty hyperlipidaemic patients on a cholesterol-poor diet were selected on the basis of a raised lipoprotein (a) (Lp(a); apo (a) > 300 U/litre) and treated with 1000 mg MgO per day during 6 weeks. Serum magnesium slightly increased compared to pretreatment levels (P < 0.001). Serum apo(a) concentrations (mean +/- S.D.) were not affected: pretreatment level 963 +/- 552 U/litre; during treatment 999 +/- 536 U/litre; and after washout 995 +/- 524 U/litre. Serum cholesterol increased slightly during MgO treatment because of an increase in LDL-cholesterol (10 per cent) and returned to pretreatment levels after a washout period.

Administration, Oral↗
PubMed2005

Magnesium proteinate is more protective than magnesium oxide in heat-stressed quail.

We evaluated the effects of dietary supplementation with Mg-oxide and Mg-proteinate on performance; nutrient digestibilities; malondialdehyde (MDA) concentrations in serum, liver, and thigh meat; and serum cholesterol and triacylglycerol concentrations in Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature. The birds (n = 360; 10 d old) were randomly assigned to 12 treatment groups consisting of 6 replicates of 5 birds each in a 2 x 2 x 3 factorial arrangement (temperature, Mg source, Mg level). Birds were maintained in temperature-controlled rooms at 22 degrees C for 24 h/d or 34 degrees C for 8 h/d (0900-1700 h) and fed a basal diet or that diet supplemented with 1 or 2 g Mg-oxide or Mg-proteinate/kg of diet. Heat exposure decreased (P = 0.0001) live weight gain, feed intake, feed efficiency, and carcass weight in quail fed the basal diet. A linear increase in feed intake (P = 0.008) and body weight (P = 0.001), and improvements in feed efficiency (P = 0.001), carcass weight (P < 0.0001), digestibility of dry matter, organic matter, crude protein, and ether extract were found in Mg-supplemented, heat-stressed quail. The effects of Mg-proteinate were greater than those of Mg-oxide (P < or = 0.0001). Serum Mg (P = 0.001) concentration increased, whereas the concentration of MDA in serum (P = 0.0001), liver (P = 0.04), and thigh meat (P = 0.0001) and serum triglyceride and cholesterol concentrations decreased linearly (P = 0.001) with the level of Mg in the diet. Interactions between dietary Mg source, temperature, and level of supplementation (P < or = 0.05) were found for several variables. Results of the present study suggest that supplementation with Mg-proteinate is more protective than Mg-oxide in reducing the negative effects of heat stress in quail.

Animal Feed↗
PubMed2004

Use of a byproduct of magnesium oxide production to precipitate phosphorus and nitrogen as struvite from wastewater treatment liquors.

This paper describes a series of experiments designed to recover phosphorus and nitrogen from sewage in the form of struvite (MgNH(4)PO(4).6H(2)O), a potential fertilizer. Nitrogen and phosphate were recovered from a filtrate of digested sludge dewatered at the Arroyo del Soto Waste Water Treatment Plant (WWTP) (Madrid, Spain). A byproduct of the Spanish magnesite mining and MgO production industry was used as the magnesium source. The precipitating performance of this byproduct was compared to that of conventional chemical reagents such as pure MgO. The precipitates obtained were subjected to chemical, light microscopy, and X-ray diffraction analysis. The findings indicate the precipitate recovered using this byproduct contains several minerals with a predominance of struvite. Optimal purity ( approximately 80% struvite) was achieved using the sieved <0.04 mm grain size fraction of the byproduct at doses corresponding to a molar Mg:P ratio of 1.6.

Chemical Precipitation↗
PubMed1989

Comparison of methods to determine relative bioavailability of magnesium in magnesium oxides for ruminants.

Two Mg balance trials were conducted with wethers to compare relative bioavailability of Mg in several Mg oxides with that of reagent grade sulfate as determined by different methods. In Experiment 1,600 ppm Mg as sulfate or four feed grade oxides varying in origin and particle size were added to a semi-purified basal diet (200 ppm Mg). Diets were fed at 800 g/d to 30 crossbred wethers during the 14-d trial and fecal and urinary collections were made during the last 7 d. In Experiment 2, the basal corn-soybean meal-cottonseed hull diet (1387 ppm Mg) was supplemented with 0, 700, 1400, or 2100 ppm added Mg as reagent grade sulfate or 1400 ppm Mg as three of the oxides from Experiment 1 and fed at 1000 g/d to 35 wethers. Urine was collected daily for 10 d and feces were collected on d 7 through 10. In Experiments 1 and 2, absorption of Mg from the oxide of brine origin and larger particle size distribution was lower than that from sulfate, but there was no difference in absorption for sheep fed oxides derived from sea water or calcined magnesite. In Experiment 2, urinary Mg excretion on d 4 and 5 of the collection was lower for sheep fed the brine oxide than for those fed sulfate or oxide from calcined magnesite. Urinary Mg excretion on d 4 and 5 following addition of 1400 ppm Mg to practical diets could be used to predict bioavailability of Mg.

Animal Feed↗
PubMed2001

Carbon nanotube-magnesium oxide cube networks.

For future applications based on carbon nanotubes, two- and three-dimensional architectures of nanotubes need to be assembled. In many cases this will involve the creation of nanotube units and nodes from which these nanotubes can be distributed in a network. We demonstrate that this idea is plausible by using a template of the correct dimensions and shape, and that has facets that provide the right growth conditions: submicrometer-sized MgO cubes are used to grow nanotubes by chemical vapor deposition. The resulting networks often show that the MgO cubes function as distribution sites for arrays of aligned nanotubes.

Crystallization↗
PubMed1988

Effect of sodium bicarbonate and magnesium oxide in an alfalfa-based total mixed ration fed to early lactating dairy cattle.

Forty-eight lactating Holstein cows were fed a total mixed ration of 57% concentrate and 43% forage (dry basis) for 12 wk postpartum. Treatments consisted of 1) no added buffers, 2) .4% MgO, 3) .8% NaHCO3, and 4) .8% NaHCO3 plus .4% MgO of the total ration DM. Body weight, DM intake, and milk yield and composition were unaffected by treatment. Gross efficiency of milk production was decreased by the addition of NaHCO3 or MgO. Buffer supplementation had no effect on ruminal volatile fatty acid concentration or blood chemistries.

Animal Feed↗
PubMed1991

Positive holes in magnesium oxide. Correlation between magnetic, electric, and dielectric anomalies.

Magnetic susceptibility measurements of high purity MgO single crystals (<50-wt. ppm transition metals) by means of a vibrating-sample magnetometer shows an anomaly at 800 K. At the same temperature the electric conductivity increases anomalously, the static dielectric constant epsilon increases from 9 to approximately 150, a pronounced positive surface charge appears, and Fe2+ in the MgO matrix oxidizes to Fe3+. The data are consistent with O2(2-) (peroxy) defects, representing self-trapped, spin-paired positive holes at Mg2+ vacancy sites. Diamagnetic at low temperatures, the holes start to decouple their spins > 600 K, probably forming at first V0 centers (two O- at an Mg2+ vacancy), then V- centers (single O- at an Mg2+ vacancy), and releasing mobile O- states. These O- represent itinerant charge carriers on acceptor levels near the O 2p-dominated valence band and conduct by O- /O2- valency fluctuations. The O- concentration is of the order of 8 X 10(19) cm-3.

Crystallization↗
PubMed1985

Effects of dietary supplementation with ethoxyquin, magnesium oxide, methionine hydroxy analog, and B vitamins on tansy ragwort (Senecio jacobaea) toxicosis in beef cattle.

Dried tansy ragwort containing pyrrolizidine alkaloids was fed as 2.5% of a complete (control) diet to Hereford steers, with and without (basal) a mixture of additives. The additives provided a dietary supplement equivalent to 0.1% ethoxyquin, 1% methionine hydroxy analog, 2% MgO, 2.7 mg of vitamin B6/kg of diet, 50 micrograms of vitamin B12/kg of diet, 0.45 g of folic acid/kg of diet, and 0.2 g of cobalt/kg of diet. The additives did not alter tansy ragwort toxicity substantially, as assessed by liver histologic changes, sulfobromophthalein clearance rate, and serum gamma-glutamyl transpeptidase activity. After 281 days, 1 of 4 steers fed the basal diet was alive, whereas 3 of 4 steers in the basal plus additives group were alive, suggesting some protective activity. The chronic lethal dose of tansy ragwort in steers was 3.6% of initial body weight.

Animals↗
PubMed1989

Solid-state interaction of magnesium oxide and ibuprofen to form a salt.

During formulation development work involving ibuprofen, a solid-state interaction between MgO and ibuprofen was observed. In this study the interaction of MgO and ibuprofen was investigated for 1:1 and 2:1 M mixtures of ibuprofen and MgO, which had been stored at 55 degrees C, using the differential scanning calorimetric (DSC), thermogravic analysis (TGA), and multiple internal reflectance infrared (MIR) techniques. Evidence for the reaction was the disappearance of the melting endotherm at 79 degrees C and appearance of a new endotherm at 161 degrees C after less than 1 day of storage at 55 degrees C and, also, the change in the physical appearance of the mixtures. Comparison of the DSC, TGA, and MIR data for the reacted ibuprofen and MgO mixtures and synthetic Mg(ibuprofen)2 indicated that MgO and ibuprofen react to form the Mg salt of ibuprofen. The interaction of ibuprofen and MgO was also studied at 30 and 40 degrees C, using 1:1 M mixtures. At 30 degrees C no significant interaction was observed for up to 80 days; however, at 40 degrees C a reaction was evident on day 1. NaHCO3, K2CO3 1.5H2O, CaO, and Mg(OH)2 also showed solid-state reactions with ibuprofen. MgCl2 and Al(OH)3 did not show this reaction.

Calorimetry, Differential Scanning↗
PubMed1999

Carboxylic and dicarboxylic acids extracted from crushed magnesium oxide single crystals.

Carboxylic and dicarboxylic acids (glycolic, oxalic, malonic and succinic) have been extracted with tetrahydrofuran (THF) and H2O from large synthetic MgO crystals, crushed to a medium fine powder. The extracts were characterized by infrared spectroscopy and 1H-NMR. The THF extracts were derivatized with tert-butyldimethylsilyl (t-BDMS) for GC-MS analysis. A single crystal separated from the extract was used for an x-ray structure analysis, giving the monoclinic unit cell, space group P21/c with ao = 5.543 A, bo = 8.845 A, co = 5.086 A, and beta = 91.9 degrees, consistent with beta-succinic acid, HOOC(CH2)COOH. The amount of extracted acids is estimated to be of the order of 0.1 to 0.5 mg g-1 MgO. The MgO crystals from which these organic acids were extracted grew from the 2860 degrees C hot melt, saturated with CO/CO2 and H2O, thereby incorporating small amounts of the gaseous components to form a solid solution (ss) with MgO. Upon cooling, the ss becomes supersaturated, causing solute carbon and other solute species to segregate not only to the surface but also internally, to dislocations and subgrain boundaries. The organic acids extracted from the MgO crystals after crushing appear to derive from these segregated solutes that formed C-C, C-H and C-O bonds along dislocations and other defects in the MgO structure, leading to entities that can generically be described as (HxCyOz)n-. The processes underlying the formation of these precursors are fundamental in nature and expected to be operational in any minerals, preferentially those with dense structures, that crystallized in H2O-CO2-laden environments. This opens the possibility that common magmatic and metamorphic rocks when weathering at the surface of a tectonically active planet like Earth may be an important source of abiogenically formed complex organic compounds.

Carboxylic Acids↗
PubMed1990

Intestinal acid flow, dry matter, starch and protein digestibility and amino acid absorption in beef cattle fed a high-concentrate diet with defluorinated rock phosphate, limestone or magnesium oxide.

Five Angus heifers (285 kg) with duodenal and ileal cannulas were used to study the effects of feeding mineral acid neutralizers on digesta and fecal pH, intestinal acid flow, DM, starch and CP digestion and amino acid absorption in cattle fed a high-concentrate diet (7.5 kg/d). The experimental design was a 5 x 5 latin square. Treatments included control diet alone or control diet with the addition of 1.60% defluorinated rock phosphate-medium (DRP-M, 77% greater than 150 mu but less than 1,180 mu), 1.60% defluorinated rock phosphate-coarse (DRP-C, 85% greater than 850 mu but less than 1,700 mu), 1.28% limestone (92% greater than 150 mu but less than 850 mu) or .50% MgO, (81% greater than 250 mu but less than 1,180 mu), as an as-fed basis. Ileal pH was increased (P less than .05) from 7.49 to 7.85 by MgO. Fecal pH was increased (P less than .05) in this order: MgO (7.18) greater than DRP-M (6.86) = limestone (6.86) = DRP-C (6.75) greater than control (6.54). Liquid flow to the duodenum was increased (P less than .05) an average of 19.7% by the mineral treatments. Duodenal acid concentrations (mEq/liter) were greatest (P less than .05) for DRP-M (65.4) and DRP-C (64.0) vs limestone (55.5) and MgO (54.4). Acid flow to the intestine was increased (P less than .05) to 4.02, 4.53 and 4.82 Eq/d for animals fed limestone, DRP-M and DRP-C, respectively, from 3.51 Eq/d for control animals. Total tract DM, starch and CP digestibilities were similar (P greater than .10) among treatments. Limestone and DRP-M increased (P less than .10) the partial digestibility of most amino acids by about 6.8%. Mineral treatments did not increase total tract digestion of starch or CP. However, cattle fed DRP-M and limestone may have used protein more efficiently.

Amino Acids↗