Narrow Results

Fluoride (F) distributions in a synthesized hydroxyl apatite (HAp) block of uniform structure and in teeth were measured using in-air micro-PIGE (particle induced gamma-ray emission) and micro-PIXE system, which was developed at the Japan Atomic Energy Agency (JAEA) in Takasaki. We used a nuclear reaction ¹⁹F(p,αγ)¹⁶O to measure F density. The characteristic important feature of this technique is that it can measure F quantitatively in a microscopic area of the specimen placed in air. A surface of the HAp, the enamel buccal surface of a human molar, and a class V cavity wall in dentin were applied a sodium fluoride solution (NaF) four times and immersed in a normal saline solution. After one month, specimens were cut longitudinally. The F distributions were measured from the surface toward the inner part of the cut surface. The F penetration into specimens following NaF application was quantitatively configured in a two-dimensional mapping form. This method is quite useful for characterizing F distribution in a microscopic area of a tooth.

Fluoride (F) distribution in human teeth was measured using an in-air micro-PIGE and micro-PIXE system. Class V cavities in the extracted teeth were prepared with Fluoro-Bond Shake One to provide a thin layer of an F-releasing material (FRM). The cavities were then filled with Beautifil Flow F10 (FRM, Group I) or LITE FIL IIP (non-FRM, Group II). Following a four-year period, specimens were cut longitudinally perpendicular to the cavity floor. The F distribution was measured at the floor of the cut surface. The position including 90% of the intact Ca level was defined as the wall surface. Based on this demarcation, indices of F distribution (surface F concentration and F penetration depth) were determined. Thickness of FRM thin layers varied (≈339 μm) and did not affect F distribution. Both values of F distribution indices in Group I [821–8763 (mean 3797) ppm, 34–668 (mean 241) μm] were significantly larger than those in Group II [0–7064 (mean 1865) ppm, 0–143 (mean 21) μm]. The F distribution in Group I was affected more by the filling material than by the FRM thin layer during the four-year exposure. Methodologies using this system may give insightful information for the development of new dental materials.

Whether fluorine penetrated from material completely incorporates into tooth mineral is a matter of debate, although it is well known that the fluoride from material penetrates directly into tooth structures. The purpose of this study is to determine tooth-bound fluoride uptake from fluoride-containing materials using PIGE/PIXE system at the Wakasa Wan Energy Research Center. Class V cavities in buccal surfaces of eighteen extracted human teeth were drilled and filled with six fluoride-containing materials. After being stored in distilled water for one year, a longitudinal section including materials was obtained from each tooth. Fluorine and calcium distribution of specimens were evaluated using PIGE/PIXE system. After evaluation, the specimens were immersed in 10 mL of 1M KOH solution and were agitated at room temperature for 24 h to remove a KOH soluble fluoride. The specimens were washed with 200 mL distilled water and left to dry. Again, to estimate tooth-bound fluorine (KOH-insoluble fluoride) uptake, the same portion of the specimens after KOH treatment were evaluated using PIGE/PIXE system. It was confirmed that fluorine penetrated from material partly incorporated into tooth mineral. This tooth-bound fluoride have the potential to prevent dental caries after loss of the bond between the filling material and tooth structure.

NaCaYF₆ is the formula for gagarinite. Noting the lack of luminescence studies in this material, we synthesized it using the hydrothermal method and investigated the luminescence of several lanthanides. Characteristic luminescence of Eu${}^{3+}$, Dy${}^{3+}$, Sm${}^{3+}$ and Tb${}^{3+}$ was observed. Detailed results on photoluminescence emission and excitation spectra, lifetime, chromaticity coordinates and concentration dependence of emission intensity are presented. Except for Tb${}^{3+}$, which exhibits f-d excitation, the luminescence of other activators got quenched at 1mol % concentration. Eu${}^{3+}$ emission in this host was peculiar, in that the emissions from higher ⁵D states were observed. Luminescence characteristics are explained using the known energy level diagrams for the lanthanide activators.

Fluoride-contaminated drinking water is a serious public health hazard in some parts of India. Field surveys have been conducted in fluoride-affected areas of the Birbhum district, West Bengal, India. From these surveys, it is found that in certain locations the drinking water contains less fluoride (within the permissible limit¹) than in adjoining areas. We have isolated a strain of Streptococcus species from these wells that has the ability to remove the fluoride ion from the water. We have grown the bacteria in different concentrations of fluoride and monitored the decline in the free fluoride ion concentration. A simplified model of fluoride and bacterial dynamics is proposed. The model is handled both analytically and numerically. For numerical solution mainly our own laboratory data are used. Calibration and validation are performed with different sets of experimental data. Analytical solutions show that the bacterial consumption and growth rates are the most important parameters in the system. Analysis shows asymptotic stability of the system.

The purpose of this study is to investigate the effects of normal, moderate and high doses of fluoride on rat epipyseal growth plate and surrounding bone, and to compare it with controls. In order to achieve this, 80 rats were divided into five groups (n: 16/group) and treated with 0, 1.2, 3, 50 and 100 ppm fluoridated water since birth (Groups I to V, respectively). Four rats from each group were sacrificed at 6th, 9th, 12th and 16th weeks for radiological and histopathological examinations.

There was no significant variation on programmed cell death of cartilagenous components of the growth plate and chondroid matrix histopathologically between control group and fluoride-treated groups. But, minimal irregularities on the cartilage septum of primary spongiosa were detected in one rat from Group IV and one from Group V. The main histopathologic findings of the rats which were treated with high doses of fluoride were irregular lamella, variation in calcium content, minimally enlarged Haversian canals, focal osteoblastic proliferation, rare zones of woven bone on the diaphyseal cortical bone and secondary spongiosa, increase in ossicle size and minimal focal osteoblastic proliferation on the secondary ossification center. The only consistent radiological finding was relative widening and late partial fusing of the epiphyseal growth plates of high-dose treated groups at 16th week.

As a result, high doses of fluoride did not directly affect chondrocyte morphology of growth plate on young rats. More sophisticated techniques would be beneficial for further investigations on this subject.

Some photonic crystal materials are developed as chemical detection materials. Varies of sensitive chemical group can be used for varies of chemical detection. In this paper, Polystyrene particles in 240 nm size were prepared firstly. The polystyrene particles were self-assembled into crystalline colloidal arrays. A kind of fluoride-bearing chemical, 2-Allylhexafluoroisopropanol, were induced to the Polystyrene crystalline colloidal arrays. Then the diffraction properties were test. After treated by 2-Allylhexafluoroisopropanol, the Polystyrene crystalline colloidal arrays get a change of diffraction in both the wavelength and the intensity. When exposed to saturated vapor of DMMP.

A series of five cobalt corrole complexes Co[(p-NO₂Ph)₂RCor](py)₂ where R is functionalized with different aromatic aldehydes at meso positions, was examined in acetonitrile solvent. Three of the five complexes changed color to green in 10${}^{-5}$ M acetonitrile solution. Their potential to sense anions was investigated using the colorimetric and spectroscopic approach in 14 different tetrabutyl ammonium salts of F${}^{-}$, CN${}^{-}$, CH₃COO${}^{-}$, NO${}_3^{-}$, AsO${}_3^{3-}$, AsO${}_4^{3-}$, Cl${}^{-}$, Br${}^{-}$, I${}^{-}$, ClO${}_4^{-}$, H₂PO${}_4^{-}$, S${}^{2-}$, HS${}^{-}$and PF${}_6^{-}$. Co-1, Co-2 and Co-4 shows selectivity towards F${}^{-}$, CN${}^{-}$and CH₃COO${}^{-}$ by their changing of color from green or reddish-brown to dark reddish-brown. The complexes exclusively bind these three anions at their axial positions. The binding constant determination gives the number of binding species (n) >1 at less than one equivalent concentration of anions in the acetonitrile solution of the complex. A band appeared at around 735 nm, on the other hand, suggests that a bis(CN)-derivative of corrole complex could form under >1 equivalent anionic conditions. The limit of detection for the Co-4 was superior than Co-1 and Co-2, which were 0.0068 $\mu$M for CN${}^{-}$, 0.0082 $\mu$M for F${}^{-}$and 0.0177 $\mu$M for CH₃COO${}^{-}$ ion. Although the complexes detect all three anions at less than 1 equivalent of the anion addition, the Co-1 and Co-2 are more selective towards CH₃COO${}^{-}$ion, whereas Co-4 selectively detects CN${}^{-}$anion at larger equivalents of these anions.

This report describes the selective fluorometric detection of pyrophosphate in water with a simple Al${}^{\text{III}}$-salen complex. The Al-based probe is synthesized in two steps in 30% yield and disassembled in the presence of pyrophosphate into its molecular building blocks. The released 3-chlorosalicylaldehyde signaling unit leads to a detectable signal with a 29-fold increase in fluorescence (${\lambda }_{\text{em}}$ = 513 nm; ${\lambda }_{\text{ex}}$ = 388 nm). At this emission wavelength, we did not observe a response from the Al${}^{\text{III}}$-salen probe despite its intrinsic blue fluorescence (${\lambda }_{\text{em}}$ = 460 nm;${\lambda }_{\text{ex}}$ = 347 nm). The Al${}^{\text{III}}$-complex shows excellent discrimination of pyrophosphate over other ions including phosphate containing adenosine triphosphate, phytic acid, or glyphosate and only fluoride inhibits the pyrophosphate-triggered disassembly process. Related salen-based probes with the same hydrophobic ligand framework but either Zn${}^{\text{II}}$ or Fe${}^{\text{III}}$ ions instead of Al${}^{\text{III}}$ were not sufficiently robust and therefore not suitable for analytical applications in pure water at pH 7.4.

Transparent ceramics have potential applications in various areas, including aerospace, relativistic optics industries, medical cares and defense. Specifically, they can be used as laser gain media, armor windows, IR domes, solid-state phosphors, scintillators and electro-optical components. From crystal structure point of view, transparent ceramic materials should have high crystallographic symmetries (cubic, tetragonal and hexagonal), which have minimal birefringent effect. Currently, transparent ceramics are dominantly based on oxide materials, although there are also nonoxides, such as fluorides and nitrides (oxynitrides). Transparent ceramics with pyrochlore and fluorite structures have attracted much attention in recent years, whereas fluorides are not well described in the open literature. Therefore, this paper is aimed to deliver an overview on the progress of the two categories of transparent ceramics, from material processing and characterization point of view.

After highlighting first case of fluoride (F) contamination in 1937, till then yet government fails to develop such a technique which would cheap and affordable to all. F contamination is increasing and spreading among different states of India and causative factors includes geogenic, phosphatic fertilizers, overexploitation, low nutritional status, lack of awareness and industrial effluents. Information, education and communication based project would be helpful to mitigate F contamination in drinking water.