Search results for "fluoride"
showing 10 items of 314 documents
Are low fluoride levels in drinking water really detrimental for neuropsychological neurodevelopment in childhood?
2020
Methods: Fluoride was measured in drinking water (DW) and in urine (1st and 3rd trimesters of pregnancy). The 369 mother-children pairs of the Spanish INMA cohort participating in the study reporte...
Structure and Matrix Isolation Infrared Spectrum of Formyl Fluoride Dimer: Blue-Shift of the C−H Stretching Frequency
2006
Infrared spectroscopy (IR) of formyl fluoride (HCOF) dimer is studied in low-temperature argon and krypton matrixes. New IR absorptions, ca. 17 cm(-1) blue shifted from the monomer C-H stretching fundamental, are assigned to the HCOF dimer. The MP2/6-311++G calculations were utilized to define structures and harmonic frequencies of various HCOF dimers. Among the four optimized structures, the dimer having two C-H...O hydrogen bonds possesses strongest intermolecular bonding. The calculated harmonic frequencies of this dimer structure are shifted from the monomer similarly as observed in the experiment. Thus, we suggest that the experimentally observed blue shifted C-H bands belong to the di…
Rotational spectra of isotopic species of silyl fluoride. Part I: Lamb-dip measurements and quantum-chemical calculations
2010
The Lamb-dip technique has been employed for recording the rotational spectra of three isotopic species of silyl fluoride, namely (28)SiH3F, (29)SiH3F, and (30)SiH3F, in order to improve the knowledge of their spectro- scopic parameters as well as to try to resolve their hyperfine structure. High-level quantum-chemical computations using state-of-the-art coupled-cluster techniques together with core-polarized correla- tion-consistent basis sets have been employed to provide reliable reference values for the hyperfine parameters involved and have been used to guide the experimental investigation. Analysis of the exper- imental spectra allowed to improve the accuracy of the known spectroscopi…
Determination of the irradiation field at the research reactor TRIGA Mainz for BNCT.
2009
For the application of the BNCT for the excorporal treatment of organs at the TRIGA Mainz, the basic characteristics of the radiation field in the thermal column as beam geometry, neutron and gamma ray energies, angular distributions, neutron flux, as well as absorbed gamma and neutron doses must be determined in a reproducible way. To determine the mixed irradiation field thermoluminescence detectors (TLD) made of CaF(2):Tm with a newly developed energy-compensation filter system and LiF:Mg,Ti materials with different (6)Li concentrations and different thicknesses as well as thin gold foils were used.
Trap Spectroscopy by the Glow Rate Technique using Bleaching of Colour Centres
2002
An application of the glow rate technique (GRT) for analysis of the parameters of thermostimulated decay of colour centres is presented using the data on the decay of radiation defects in LiBaF 3 :Fe crystals created by X rays at 300 K. The GRT offers a procedure for evaluation of the mean activation energy as a function of temperature in the case of arbitrary thermostimulated relaxation kinetics represented by the trap distribution function. The experimental procedure involves at least two subsequent measurements of thermostimulated decay kinetics at different heating rates. It is shown that the decay of the F type centres is governed by interaction of mobile anion vacancies with F A and F…
Evaluation of the relative thermoluminescence efficiency of LiF:Mg,Ti and LiF:Mg,Cu,P TL detectors to low-energy heavy ions
2013
Abstract The most popular types of LiF-based thermoluminescent (TL) detectors, LiF:Mg,Ti (MTS-N) and LiF:Mg,Cu,P (MCP-N), have been investigated, with respect to their dose (fluence) response and relative TL efficiency to different ion species. The detectors were irradiated using the nitrogen, iron, krypton and xenon ion beams, at energies ranging from 5.0 to 9.3 MeV/n. Supra- and sublinear response was found, for the MTS-N and MCP-N, respectively, similarly as observed for γ-rays. However, the level of nonlinearity of response of studied detectors is strongly reduced by increasing values of the ion ionization density (no supralinearity for Xe ions, for MTS-N, within calculated uncertaintie…
Dry synthesis of B-MFI, MTN- and MTW-type materials
1997
Abstract B-MFI and MTN-type materials were synthesized via the fluoride route from dry powders in the complete absence of a solution phase. Amorphous precursors obtained by drying SiO 2 · Al 2 O 3 gels at 700°C were transformed into MTN-type material in the presence of dried NH 4 F and TMACl. Amorphous precursors obtained by drying SiO 2 gels at 700°C were transformed into B-MFI in the presence of dried NH 4 F, B 2 O 3 and TPABr. Water is formed as a reaction product. However, the water vapor pressure is appreciably below the water vapor saturation pressure under the given reaction conditions. In addition, syntheses using seed crystals were carried out successfully.
Effect of application time and concentration of silver diamine fluoride on the enamel remineralization
2021
Background Silver diamine fluoride has attracted attention because of its clinical success in arresting dental caries. Thus, the aim of this study was to evaluate the effect of different application times and concentrations of silver diamine fluoride (SDF) on deciduous tooth enamel remineralization. Material and Methods Blocks of deciduous tooth enamel were categorized into six groups of 11 each: 2 control groups: intact enamel, and demineralized enamel; 38% SDF and 30% SDF which were subdivided according to application times (1 and 3 min). The microhardness of samples was determined, and all groups except the intact enamel group were subjected to pH cycling to produce initial carious lesio…
Evaluation of diode laser application on chemical analysis and surface microhardness of white spots enamel lesions with two remineralizing agents
2020
Background To investigate the effect of diode laser application and two commercial remineralizing agents on the remineralization and surface microhardness of white spot enamel lesions. Material and methods Sixty specimens were prepared then equally divided into six groups (n=10/group), according to the diode laser and the two commercial remineralizing agents applied to demineralized enamel surfaces (APF gel and sodium fluoride NaF mousse) with or without diode Laser application as follows; Group A; control, Group B; diode Laser application, Group C; APF gel application, Group D; NaF mousse application, Group E; APF gel application + diode Laser, Group F; NaF mousse application+ diode Laser.…
Enamel remineralization and surface roughness after treatment with herbal-containing toothpastes
2021
Background Oral care products containing bioactive agents obtained from extracts of plant drugs were launched. This in vitro study investigated the effects of herbal-containing toothpastes associated or not with fluoride to remineralize the enamel after cariogenic challenge with pH cycling. The chemical and physical factors of toothpastes and the enamel surface roughness after brushing were also analyzed. Material and methods Sixty bovine enamel blocks were obtained and divided into 3 thirds: intact (untreated), demineralized (artificial caries lesion), and treated (caries lesion, pH cycling, and brushing with toothpastes). Toothpastes containing herbal compounds contained no fluoride [Gall…