Magnesium-iron ratio

Bartholome, P., 1962. Iron-magnesium ratio in associated pyroxenes and olivines. Geol. Soc. Am., Petrologic Studies A volume in honour of A.F. Buddington, New York, pp. 1-20. 

Illite and montmorillonite are similar in structure and differ slightly from kaolinite in this regard. The first two are composed of two silicon-oxygen layers per octahedral layer containing iron, magnesium and aluminum and in kaolinite the ratio of tetrahedral and octahedral layers is 1. In clays thermal modification occurs at lower temperature than silica because the bonds formed between the Al, Fe, and Mg atoms and oxygen are weaker than the Si-0 bonds. 

As for the other micas, Rammelsberg (1895) confirmed the half-silicate nature also of paragonite, (H,Na)2AlSi203 (O is an obvious misprint of O ) that has Na H = 1 2. For some muscovites, he reported a R Si ratio to 3 1, and hence a mixture of normal and half silicate (these are the present phengites). Other micas, e.g., the iron-magnesium micas, have compositions which arise from a mixture of several half silicates x R SiO + y R SiO + z R Si Qi [x, y, z being three variable coefficients]. 

Early studies revealed that the rate of PHA accumulation can be increased by increasing the ratio of the carbon to nitrogen source [99]. Eventually it became evident that PHA accumulation usually occurs when cell growth is impaired due to depletion of an essential nutrient such as sulfate, ammonium, phosphate, potassium, iron, magnesium or O2 [1, 100, 103]. Suzuki and co-workers [103] studied 51 methylotrophs for their ability to produce P(3HB) from methanol. Similar nutrient limitations were found to stimulate the formation of P(3HB). However, a kinetic study of the production of P(3HB) by a fed-batch culture of Protomonas extorquens... 

Tricalcium phosphate, Ca2(P0 2> is formed under high temperatures and is unstable toward reaction with moisture below 100°C. The high temperature mineral whidockite [64418-26-4] although often described as P-tricalcium phosphate, is not pure. Whidockite contains small amounts of iron and magnesium. Commercial tricalcium phosphate prepared by the reaction of phosphoric acid and a hydrated lime slurry consists of amorphous or poody crystalline basic calcium phosphates close to the hydroxyapatite composition and has a Ca/P ratio of approximately 3 2. Because this mole ratio can vary widely (1.3—2.0), free lime, calcium hydroxide, and dicalcium phosphate may be present in variable proportion. The highly insoluble basic calcium phosphates precipitate as fine particles, mosdy less than a few micrometers in diameter. The surface area of precipitated hydroxyapatite is approximately... 

The first few decades of space exploration went by without any MS better than m/Am 4 because understanding the solar wind flow, its density, its pressure, or its temperature did not require mass resolution. Not until 1984 did a space MS fly with a resolution of about 10 [10], and it was 1994 before that increased to 100 [11], Suddenly for the first time, the solar wind isotopes of carbon, oxygen, magnesium, silicon, and iron were known, and the models could be tested. Even then, space MS had difficulty measuring rare isotopes, so that it wasn t until 2005 that solar wind samples were returned to Earth inside ultra-pure silicon wafers (the ill-fated Genesis mission [12]) to determine the important triple ratios of ieO 170 lsO. 

Brown and coworkers (17-18,47) reported compositions of dusts from cotton compresses and warehouses. Samples were removed with the aid of a sonic bath in hexane. The compresses were in Mississippi, Southeastern and Western Texas, and New Mexico. The samples in the bale press area were high in ash content with silicon the most abundant element (up to 18.7% in one New Mexico compress Scimple). Compared with card room dusts, samples from compresses were high in aluminum, silicon, chlorine, iron and magnesium and relatively low in potassium, phosphorus and zinc. The ratio of silica to silicon was high also for these scunples compared with textile mill dusts. 

Even nuclei, and in particular the class of a nuclei (oxygen, magnesium, silicon, calcium), are the basic products of nucleosynthesis in high-mass stars. They are abundantly present in the ashes of SNll events, where the cx/iron ratio is about three times the solar value. The amounts of even elements ejected by explosion of a high-mass star are, to the first approximation, independent of the star s initial metallicity. 

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