The thermal decomposition of metal formates. II. Solid state thermal decomposition studies on magnesium formate dihydrate

Magnesium formate dihydrate has been synthesized by the action of formic acid on anhydrous magnesium oxide. This product analysed as Mg(COOH)₂ · 2H₂O. Its mode of thermal decomposition has been studied by thermal methods of analysis including simultaneous DTA/mass spectrometry. Nitrogen adsorption surface area of the solid products at various stages of its decomposition have been obtained. X-Ray diffraction and scanning electron micrographs have also been used to interpret the results. The decomposition of magnesium formate took place in three stages, which includes a phase change, at 265°C. The endotherm at 430°C changed to an exotherm in the presence of air; it corresponded to the decomposition of a new anhydrous phase of magnesium formate. The effect of the sample holder and changing atmospheres on the DSC analysis has been investigated. A scheme is presented for the thermal decomposition.     

Resistance of supersulfated cement to strong sulfate solutions

One of the principal uses of supersulfated cement has been for structures exposed to sea water and sulfate bearing ground waters. The resistance to such environments has been related to the absence of calcium hydroxide and the combination of much of the free alumina into ettringite during hydration. This paper reports the resistance of SSC to sulfate solutions in which ettringite has been decomposed. Prism samples were subjected to initial water storage at 25°C for both 28 days and 6 months. Samples were also cured for 6 months at 95°C and at both 11% and 100% R.H. The control samples of 28 days were compared with the 6 months samples of a more mature undecomposed SSC paste. After curing the prisms were measured and all the samples were immersed in three sulfate solutions (0.7M Na₂SO₄ , 0.7M MgSO₄ and saturated CaSO₄), and water at the same time. Measurements of linear expansion over 6 months were carried out. Core and surface material following immersion was examined by DTG and XRD. The study indicated that SSC is resistant to sodium and calcium sulfate solutions. Strong magnesium sulfate solutions decomposed the samples under all conditions. A possible mechanism for this attack is suggested. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spectrophotometric determination of phosphorus as phosphate in organic compounds and materials of biological origin using a flow-injection manifold with a mixing chamber

Summary A flow-injection manifold with mixing chamber has been developed for the determination of phosphate by reaction with molybdate and crystal violet. The insoluble blue dye salt is kept in colloidal solution with poly(vinyl alcohol) and measured at 560 nm. The injection rate is 100 h^–1. The detection limit is 0.01 g PO ₄ ^3– /ml based on 250 l injection volumes. The system has been applied to the determination of phosphate in serum samples and after appropriate mineralisation to organic compounds and to plant materials.     

Crystalline phase of Y_2O_3 :Eu particles generated in a substrate-free flame process

In this study, factors affecting the crystal structure of flame-synthesized Y 2 O 3 :Eu particles were inves- tigated, especially the particle size effect and its interaction with Eu doping concentration. Polydisperse Y 2 O 3 :Eu (size range 200 nm to 3 m) powder samples with Eu doping concentrations from 2.5 mol% to 25 mol% were generated in either H 2 /air or H 2 /O 2 substrate-free flames. The crystal structure of the powder samples was determined by powder X-ray diffraction (XRD), which was complemented...     

The extraction, determination and speciation of tributyltin in seawater

Summary Methods have been developed for the determination, by carbon-furnace atomisation atomic absorption spectrophotometry, of inorganic and of total butyltin in seawater. Concentration/separations are based on the solvent extraction of organotin species directly into toluene and of inorganic tin as its tin(IV) 8-hydroxyquinoline chelate into chloroform. Detection limits are 0.7–0.8 ng.

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Extraktion, Bestimmung und Speziation von Tributylzinn in Seewasser

     

Highly porous and robust scandium-based metal-organic frameworks for hydrogen storage

The metal-organic frameworks NOTT-400 and NOTT-401, based on a binuclear [Sc(2)(μ(2)-OH)(O(2)CR)(4)] building block, have been synthesised and characterised; the desolvated framework NOTT-401a shows a BET surface area of 1514 m(2) g(-1) with a total H(2) uptake of 4.44 wt% at 77 K and 20 bar.     

Homotopically nontrivial solutions for a spherically symmetric gravitational field

The structure of kink solutions to the Einstein field equations is discussed and the most general form of spherically symmetric kink metric is constructed. A number of fluid solutions are investigated and an imperfect fluid solution with nonzero heat conduction is presented.     

Crystal and molecular structure of the triphenylphosphine oxide adduct of tri-3-thienyltin bromide, Ph3 PO·SnBr(C4 H3S)3

The solid state structure of the triphenylphosphine oxide (TPPO) adduct of tri-3-thienyltin bromide has been investigated by both single crystal X-ray analysis and Mössbauer spectroscopy. The crystal structure consists of discrete molecules and there is no evidence of any intermolecular tin-sulphur interactions. Each tin atom is found to be in a five-coordinate trigonal bipyramidal environment in which the three thienyl groups occupy equatorial positions. The metal atom is displaced by 0.182 Å out of the equatorial plane and towards the axial bromine. Two of the thienyl ligands exhibit rotational disorder and the lack of disorder in the remaining heteroaryl ligand is attributed to the close proximity of this group to a phenyl ligand. The Mössbauer parameters are also in accord with five-coordination for tin and are indicative of the aryl groups being equatorial.