Fluoride ions materials

Sodium fluoroborate [13755-29-8] M 109.8, m 384 , d 2.47, pK -4.9 (for fluoroboric acid H30 BF4 ). Crystd from hot water (50mL/g) by cooling to 0 . Alternatively, purified from insoluble material by dissolving in a minimum amount of water, then fluoride ion was removed by adding cone lanthanum nitrate in excess. After removing lanthanum fluoride by centrifugation, the supernatant was passed... 

Because borosilicate is a brittle material, its design stress is restricted to less than 7 N/mm. Borosilicate glass is attacked by hydrofluoric acid even when a solution contains only a few parts per million of fluoride ions, and at... 

Dissolution. Plutonium is solubilized in nitric acid solutions at Rocky Flats. The feed material consists of oxide, metal and glass, dissolution heels, incinerator ash and sand, slag, and crucible from reduction operations. The residues are contacted with 12M HNO3 containing CaF2 or HF to hasten dissolution. Following dissolution, aluminum nitrate is added to these solutions to complex the excess fluoride ion. 

The performance in Zn-MnC>2 alkaline cells of electrolytic manganese dioxide produced in the presence of fluoride ions is compared with commercial EMD materials by I. Makyeyeva et al. The material produced in the presence of fluoride ions was shown to have superior utilization to the commercial EMD. The authors state that the improved... 

The dithieno[3,2-6 2, 3 -<7 phosphole 63 has been designed as a very sensitive material for detection of fluoride ions <06OL495>. Cationic dithieno[3,2-6 2, 3 -<7 phospholes alkylated at the phosphorus atom have also been prepared for application as building blocks... 

This material is a precursor for Sarin (C01-A002) and is also commonly found as a decomposition product/impurity (up to 20% ) in sarin. If fluoride ion is present and the pH falls below 7, sarin will be formed. This material has been used as a simulant for nerve agents in government tests. 

In an attempt to produce TS-1 at low cost, alternative, cheaper sources of Ti and Si and other bases such as binary mixtures of (tetrabutylammonium and tetraethylammonium hydroxides), (tetrabutylphosphonium and tetraethylpho-sphonium hydroxides), (tetrapropylammonium bromide and ammonia, water, hexanediamine, n-butylamine, diethylamine, ethylenediamine, or triethanolamine) in place of TPAOH have been used (284—294). TS-1 was synthesized in the presence of fluoride ions but the material thus formed contained extraframework Ti species (295-297). 

In contrast to the cathodic reduction of organic tellurium compounds, few studies on their anodic oxidation have been performed. No paper has reported on the electrolytic reactions of fluorinated tellurides up to date, which is probably due to the difficulty of the preparation of the partially fluorinated tellurides as starting material. Quite recently, Fuchigami et al. have investigated the anodic behavior of 2,2,2-trifluoroethyl and difluoroethyl phenyl tellurides (8 and 9) [54]. The telluride 8 does not undergo an anodic a-substitution, which is totally different to the eases of the corresponding sulfide and selenide. Even in the presence of fluoride ions, the anodic methoxylation does not take place at all. Instead, a selective difluorination occurs at the tellurium atom effectively to provide the hypervalent tellurium derivative in good yield as shown in Scheme 6.12. 

Tetra-n-butylammonium triphenyldifluorosilicate has been found to be a more reliable source of fluoride ions compared with the simple fluoride or hydrogen fluoride salts. The salt is available as an anhydrous non-hygroscopic material [36] and, although it is less nucleophilic and a weaker base than the ammonium fluo-... 

Anion conduction, particularly oxide and fluoride ion conduction, is found in materials with the fluorite structure. Examples are Cap2 and Zr02 which, when doped with aliovalent impurities. Fig. 2.2, schemes 2 and 4, are F and 0 ion conductors, respectively, at high temperature. The 3 polymorph of 61303 has a fluorite-related structure with a large number of oxide vacancies. It has the highest oxide ion conductivity found to date at high temperatures, > 660 °C. 

Fluorine is an essential element involved in several enzymatic reactions in various organs, it is present as a trace element in bone mineral, dentine and tooth enamel and is considered as one of the most efficient elements for the prophylaxis and treatment of dental caries. In addition to their direct effect on cell biology, fluoride ions can also modify the physico-chemical properties of materials (solubility, structure and microstructure, surface properties), resulting in indirect biological effects. The biological and physico-chemical roles of fluoride ions are the main reasons for their incorporation in biomaterials, with a pre-eminence for the biological role and often both in conjunction. This chapter focuses on fluoridated bioceramics and related materials, including cements. The specific role of fluorinated polymers and molecules will not be reviewed here. 

There are multiple applications of fluoridated bioceramics, essentially as bone and tooth substitutes (Table 1), involving bulk ceramics, glasses, composite materials and coatings for medical devices and surface treatments. In some cases, fluoride ions can leach out of the material inducing a direct biological effect in a soluble form. However, considering the affinity of fluoride ions for apatite... 

Several effects of fluoride ions have been claimed (Table 1) concerning the stability of the biomaterials, the implant-tissue interface, or the tissue itself. The incorporation of fluoride ions in apatitic materials is generally aimed at increasing their stability and decreasing their solubility. 

Resin-modified glass-ionomers, like their conventional counterparts, are capable of releasing fluoride [224,264,265], and in greater amounts under acid conditions than neutral ones [265], Release rates and release profiles have been shown to be comparable with those from conventional glass-ionomer cements [264,265], Other ions have also been shown to be released by these materials and, as for fluoride, these ions show a greater release under low pH conditions [265], However, the level of phosphorus released has been shown to be much lower from resin-modified glass-ionomers than from conventional ones [263], This suggests that there is little or no possibility of association of fluoride as monofluorophosphate, but rather that almost all of the fluoride is released either as the free fluoride ion or as alumino-fluoride complex ions. 

Methods for determining any form of fluorine in any type of material generally rely on the determination of fluorine in the form of free inorganic fluoride ion (F ). 

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