Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FLUORIDATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed2005

Anhydrous phosphazenium fluorides as sources for extremely reactive fluoride ions in solution.

Several peralkylated polyaminophosphazenium cations were evaluated for the generation of novel anhydrous F- salts. Two of them have been characterized by X-ray analysis and are particularly soluble, even in apolar aprotic solvents like benzene or THF, one of them even at -30 degrees C. Such solutions probably represent the most basic metal-free and stable media known to date. Comparison of these fluorides with known F- sources demonstrates that they are of unprecedented reactivity and selectivity in E2 elimination reactions.

Journal Article↗
PubMed2006

Preparation and characterization of silver-poly(vinylidene fluoride) nanocomposites: formation of piezoelectric polymorph of poly(vinylidene fluoride).

In situ Ag nanoparticles are produced on reduction of Ag+ with N,N-dimethylformamide in the presence of poly(vinylidene fluoride) (PVF2). The plasmon band transition is monitored with time in the reaction mixture for three sets of experiments by UV-vis spectroscopy. The plasmon band absorbance increases sigmoidally with log(time). Analysis of the data with the Avrami equation yields an exponent n value between 1.5 and 2.0, indicating two-dimensional nucleation with linear or diffusion controlled growth. The TEM study of the polymer nanocomposites (PNC) indicates both spherical and rodlike morphology for PNC0.5 and PNC2.5 samples, whereas the PNC11 sample has spherical and agglomerated structures (the numerical number associated with PNC indicates percentage (w/w) of Ag in the nanocomposite). The WAXS and FTIR studies indicate the formation of piezoelectric beta-polymorphic PVF2 in the nanocomposites. The DSC study indicates some increase of the melting point and enthalpy of fusion of PVF2 in the nanocomposite, although with increase in Ag nanoparticle concentration the increase is smaller. The crystallization temperatures of PNCs also increased, indicating nucleating effect of Ag nanoparticles in the composite. In the TGA curves, the PNCs exhibit a three-step degradation process. The degradation temperatures of PNCs are lower than that of PVF2. The storage modulus data indicate a significant reinforcement of the mechanical property in the PNCs where also the reinforcement effect decreases with increasing nanoparticle concentration. Both the loss modulus and tan delta plots indicate two peaks; the lower temperature peak has been attributed for glass transition temperature, whereas the higher one has been attributed to a similar type relaxation process for the crystalline-amorphous interface. The increase in the glass transition is marginal for the PNCs, but the increase of later transition temperature is somewhat higher. The FTIR study shows that the dipolar interaction of the >CF2 dipole with the surface charges of Ag nanoparticle stabilizes the nanoparticle in the nanocomposite.

Journal Article↗
PubMed2004

Effects from pretreatment of stannous fluoride versus sodium fluoride on enamel exposed to 0.1 M or 0.01 M hydrochloric acid.

Preventing enamel erosions caused by acidic soft drinks or from vomiting during eating disorders is a challenge in current dental research. The aim of this study was to examine whether pretreatment of dental enamel with a solution of 0.4% SnF2 could prevent dissolution of human enamel exposed to solutions of 0.1 M HCl, pH 1.2 or 0.01 M HCl at pH 2.2. Human enamel was pretreated for 18 h with a solution of 0.4% SnF2 and with control solutions of 2% NaF or distilled water, and then exposed to HCl solutions. Similar experiments were performed with teeth treated for 2 min SnF2 and then 4 min HCl. The effect was monitored by scanning electron microscopy (SEM) and by chemical analysis. At pH 2.2, NaF and water treatments showed minor inhibition of enamel dissolution, whereas SnF2 inhibited demineralization significantly also after 2 min pretreatment and 4 min HCl exposure. At pH 1.2, SEM showed severe dissolution of the enamel surfaces regardless of pretreatment. As pH of stomach vomit is usually > 1.5, SnF2 may be an interesting agent for use in the treatment and prevention of dental erosions even in patients with frequent vomiting episodes.

Bicuspid↗