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Results for “Magnesium Compounds”

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At least 199 records · Page 11Linked to original sources
PubMed1984

Comparative study of four antacids.

Four antacid preparations have been studied in a stratified, randomized, double-blind trial to evaluate criteria which determine patients' acceptance of this type of therapy. There was a considerable range of judgements about palatability, but preference was determined not only by factors such as the smell, taste, texture and after-taste of the preparation, but also by the order in which the antacids were tested and by the age and sex of the patient. The preparations also differed considerably in acid-neutralizing capacity and ability to bind bile salts, as well as cost. We conclude that individuals requiring antacid therapy should be allowed to chose from among a range of preparations, in order to maximize compliance.

Adult↗
PubMed1982

Effect of the pH-zero point of charge relationship on the interaction of ionic compounds and polyols with aluminum hydroxide gel.

The adsorption of magnesium nitrate, docusate sodium, and mannitol by chloride-containing aluminum hydroxide gel or aluminum hydroxycarbonate gel can be directly related to the surface charge characteristics of the aluminum hydroxide gel as determined by the pH-zero point of charge (ZPC) relationship. Magnesium cation is completely adsorbed under pH conditions where the gel has a negative surface charge, i.e. when the pH is above the ZPC. Docusate sodium is more strongly adsorbed when the pH-ZPC relationship causes the surface charge of aluminum when the pH-ZPC relationship causes the surface charge of aluminum hydroxycarbonate gel to be positive indicating adsorption of the docusate anion. However, adsorption also occurred when the pH was above the ZPC suggesting that adsorption of the hydrophobic portion of docusate anion by van der Waals forces also contributes to the overall adsorption mechanism. Mannitol is adsorbed under all pH conditions. However, greater adsorption occurs when the pH is above the ZPC. Maximum hydrogen bonding is believed to occur when mannitol acts as the proton donor and the negative aluminum hydroxycarbonate gel surface serves as the proton acceptor.

Adsorption↗
PubMed1997

The spectrum of comet Hale-Bopp (C/1995 O1) observed with the Infrared Space Observatory at 2.9 astronomical units from the sun.

Comet Hale-Bopp (C/1995 O1) was observed at wavelengths from 2.4 to 195 micrometers with the Infrared Space Observatory when the comet was about 2.9 astronomical units (AU) from the sun. The main observed volatiles that sublimated from the nucleus ices were water, carbon monoxide, and carbon dioxide in a ratio (by number) of 10:6:2. These species are also the main observed constituents of ices in dense interstellar molecular clouds; this observation strengthens the links between cometary and interstellar material. Several broad emission features observed in the 7- to 45-micrometer region suggest the presence of silicates, particularly magnesium-rich crystalline olivine. These features are similar to those observed in the dust envelopes of Vega-type stars.

Carbon Dioxide↗
PubMed2006

Iron-magnesium silicate bioweathering on Earth (and Mars?).

We examined the common, iron-magnesium silicate minerals olivine and pyroxene in basalt and in mantle rocks to determine if they exhibit textures similar to bioweathering textures found in glass. Our results show that weathering in olivine may occur as long, narrow tunnels (1-3 microm in diameter and up to 100 microm long) and as larger irregular galleries, both of which have distinctive characteristics consistent with biological activity. These weathering textures are associated with clay mineral by-products and nucleic acids. We also examined olivine and pyroxene in martian meteorites, some of which experienced preterrestrial aqueous alteration. Some olivines and pyroxenes in the martian meteorite Nakhla were found to contain tunnels that are similar in size and shape to tunnels in terrestrial iron-magnesium silicates that contain nucleic acids. Though the tunnels found in Nakhla are similar to the biosignatures found in terrestrial minerals, their presence cannot be used to prove that the martian alteration features had a biogenic origin. The abundance and wide distribution of olivine and pyroxene on Earth and in the Solar System make bioweathering features in these minerals potentially important new biosignatures that may play a significant role in evaluating whether life ever existed on Mars.

Earth, Planet↗
PubMed1985

Effects of prolonged inhalation of silica and olivine dusts on immune functions in the mouse.

Immunologic responses were determined in Balb/c mice following intermittent silica or olivine inhalations for 150, 300, or 570 days. Animals dust-exposed for 570 days were tested immediately postexposure, while those exposed for 150 or 300 days were tested immediately or were rested for 30 or 150 days as a measure of possible recovery from effects of the dust inhalations. Silica inhalation suppressed the number of specific plaque-forming cells (PFC) in the spleen produced in response to aerosolized Escherichia coli bacteria. When tested after 570 days, silica inhalation also reduced the ability of alveolar macrophages to phagocytize Staphylococcus aureus in vitro. Olivine inhalation also suppressed splenic PFCs and alveolar macrophage phagocytosis, but to a lesser degree than silica. In animals tested after 570 days of dust exposure, it was determined that the ability to lyse allogeneic tumor cells in vitro was impaired by olivine slightly more than by silica, while antibody-dependent cell-mediated cytotoxic and mitogenic responses by splenic lymphocytes were unchanged by inhalation of either dust. The effects of increased exposure periods, and of recovery periods after exposure, were confounded by age-related immunologic changes which were present after the longer exposures.

Aerosols↗
PubMed2005

Study on adsorption of glyphosate (N-phosphonomethyl glycine) pesticide on MgAl-layered double hydroxides in aqueous solution.

MgAl-layered double hydroxides with different interlayer anions (nitrate, carbonate and chloride) were evaluated for their abilities to adsorb the organic pesticide glyphosate (N-phosphonomethyl glycine, Gly). The adsorption isotherms of Gly on layered double hydroxides (LDHs) nitrate were described by the Langmuir equation at lower equilibrium concentration of Gly (C(e)<1.0 mmol/L), and the Gly adsorption capacity on LDHs increased with the layer charge density, i.e. the structural Al3+/Mg2+ ratio. Gly adsorption on LDHs nitrate generally occurred through two processes, external surface adsorption and interlayer anion exchange. The adsorption amount on LDHs at C(e)=1.0 mmol/L decreased in the order of interlayer anions: Cl(-)>NO3(-)>CO3(2-).

Aluminum Compounds↗
PubMed1983

Catheter encrustation by struvite.

Encrusted catheters from 10 female patients were the source of 26 samples of deposits which were examined by X-ray diffraction. Four different types of catheter were represented. The only detectable compound in all of the samples was ammonium magnesium orthophosphate hexahydrate (NH4MgPO4 . 6H2O), which occurs naturally as the mineral struvite.

Aged↗
PubMed1993

[Struvite stone dietetics: 1. Effect of different feed rations on the urine pH value of cats].

In this investigation the base excess of cat foods (sum of alkalogenic compounds calcium, magnesium, sodium and potassium minus sum of acidifying compounds phosphorus, chloride, methionine and cysteine; base excess in mmol/kg dry matter = Ca*2+Mg*2+Na+K-(met(-)+cys)*2-P*2-Cl) as a method of predicting the influence of food on the urinary pH was tested. The base excess and the effect on urinary pH (feeding experiment with 4 to 6 adult cats per trial) was determined in 10 commercial cat foods (3 moist, 3 dry type foods, 4 struvite diets) as well as the influence of several additives (CaCl2, CaCO3, Ca-lactate, CaHPO4, phosphoric acid in 2 doses, NH4Cl, ascorbic acid). After the intake of commercial cat foods the mean urine pH ranged between 6.58 and 7.89, after the intake of struvite diets it ranged between 6.36 and 7.57. The addition of Ca-carbonate or -lactate led to a significant increase of urine pH, Ca-phosphate and ascorbic acid had no effect, while Ca-Chloride, phosphoric acid and ammonium chloride led to a decrease. There was a highly significant correlation between the base excess in the food (x; mmol/kg dry matter) and the mean urine pH (y; y = 6.72 + 0.0021 x; r = 0.96**).

Animal Feed↗
PubMed1999

Analysis of the environment of beryllium, magnesium and alkaline earth atoms in oxygen-containing compounds.

About 2100 inorganic and organometallic compounds containing beryllium, magnesium and alkaline earth atoms (M) were investigated with Voronoi-Dirichlet polyhedra (VDPs). It is shown that the coordination numbers (CNs) of the M atoms in MO(n) coordination polyhedra can be determined by means of VDPs without crystal-chemical radii. The distributions of the M-O distances in the coordination spheres of the M atoms are bimodal for M = Be or Mg and monomodal for the other alkaline earth metals. Beryllium and magnesium coordination polyhedra containing weak M-O contacts were classified by variants of their distortions. It is found that the volume of the domains of the Mg, Ca, Sr and Ba atoms is independent of their CNs at CN >/= 6 (up to 16 for barium). The possibility of using the model of deformable spheres to describe the crystal structure of the compounds investigated is suggested.

Journal Article↗
PubMed2006

Prenatal therapy for fetal growth restriction.

The choice of therapy for fetal growth restriction (FGR) depends on the nature of the insult that led to the development of FGR. Many etiologic factors are either not amenable to therapy or fetal growth has not been improved by treatments that benefit the mother. Many therapeutic approaches have been used to improve fetal condition. None of the approaches have been of value in a consistent manner. We present the numerous approaches, and their rationale for their use, that have been tried to treat the growth impaired fetus. The evidence from the randomized clinical trials is summarized and their conclusions given.

Adrenergic beta-Agonists↗