• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2145-2148
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• 2012

A new thiourea based receptor (1) was synthesized and applied to fluoride ion recognition in acetonitrile solution. Receptor 1 displayed dual changes in absorption and fluorescence emission intensities selectively for fluoride ions. The interaction of 1 with fluoride undergoes a deprotonation process that is confirmed by $^1H$ NMR titration.

• Environmental Analysis Health and Toxicology
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• 제14권3호
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• pp.113-120
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• 1999

Fluorination of drinking water has been used world widely to reduce the incidence of caries. Recently, contradictory results on the cytotoxicity of fluoride compounds are reported. In addition, there are attempts to use fluorosilicate for fluorination of drinking water in Korea, therefore, we tried to analyze the cytotoxicity of fluoride compounds on oral epidermoid carcinoma (KB and A253) and osteosarcoma (HOS and MG-63) cells in this study. We treated cells with 0, 10, 50 and 250 ppm of fluorosilicic acid (domestic or from Fluka, F$\_$6/H$_2$Si), sodium fluorosilicate (F$\_$6/Na$_2$Si), sodium fluoroacetate (FCH$_2$CO$_2$Na), sodium fluoride (NaF) or potassium fluoride(KF) and measured the relative cell survival by MTT assay. At the concentration of < 10ppm, no significant cytotoxicity was observed. At 50 ppm, each cells revealed different response to fluoride treatment. Among cells used in this study, MG-63 was the most resistant to fluoride treatment. Comparable toxicity data from domestic and imported fluorosilicic acids were obtained. When we compared the relative cytotoxicity of fluoride compounds against their fluoride contents, the differences in relative cell survival were smaller. Most of cells showed < 20% of survival at 250 ppm. In order to analyze the pH dependence of the cytotoxicity of fluorosilicates, the pH of cell culture media containing fluorosilicate was adjusted to 7.4 or 6.5 and the relative cytotoxicity was measured. At lower pH, about 10% higher cytotoxicity was obtained. Thus, our data suggested that the toxicity of domestic fluorosilicic acid was similar to that of fluorosilicic acid from Fluka, and the cytotoxicity of fluoride compounds was dependent on the relative content of fluoride and pH.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1287-1289
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• 2009

Three different fluoride compounds were used for preparation of $BaAl_2S_4$:Eu thin-films. The emission intensity of these devices were higher than that of the thin-films deposited without fluoride materials, and the appropriate annealing temperature decreased with fluoride dopants. It is related to the fluoride compounds accelerate the crystallization of $BaAl_2S_4$ at low temperature.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1931-1938
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• 2021

Uranium ingot is produced by metallothermic reduction of uranium tetrafluoride using magnesium or calcium as reductant. Presence of oxygen containing compounds viz. uranyl fluoride and uranium oxide in the starting uranium fluoride has a significant effect on the firing time, final temperature of the charge, slag-metal separation and hence the metal recovery. As reported in the literature, the maximum tolerable limit for uranyl fluoride in the UF₄ is 2.5 wt% and limit for uranium oxide content is in the range 2-3 wt%. No theoretical or experimental basis is available till date for these limits. Analyses have been carried out in this study to understand the effect of UO₂F₂ concentration in the starting fluoride on the final temperature of the products and thus the reduction characteristics. UF₄ having uranyl fluoride concentration, less than as well as more than 2.5 wt%, have been investigated. Thermodynamic calculations have been carried out to arrive at a general expression for the final temperature attained by the products during calciothermic reduction of UF₄. Finally, an upper limit for the oxygen containing impurities has been estimated using the CaO-CaF₂ phase diagram.

• 한국교육논총
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• 제37권1호
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• pp.33-45
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• 2016

본 연구는 다양한 치환기를 포함하고 있는 3종의 보레인 화합물을 합성하고, UV/Vis 하에서 합성된 화합물이 내는 흡광을 이용하여 유기 용매 하에서 매우 적은 농도로 존재하는 불소 이온($F^-$)의 검출에 적용하고자 하는 것이다.

• 공업화학
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• 제17권5호
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• pp.483-489
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• 2006

희토류 화합물인 $La_{2}O_{3}$ 및 $CeO_{2}$ 시약과 이들을 함유하는 희토류 광석을 이용하여 제철 폐수 중의 불소 및 유해 중금속 제거에 대하여 연구하였다. 용액 중 불소에 대한 희토류 원소의 제거 반응기구는 $La^{3+}$ 및 $Ce^{4+}$ 등의 양이온이 불소 이온과 불용성 화합물을 형성하는 것으로 알려져 있다. 기존의 불소 제거에 사용되고 있는 소석회와 비교한 결과 $La_{2}O_{3}$ 및 $CeO_{2}$ 의 불소제거 효율이 높았다. HF 용액에서의 제거 효율은 $CeO_{2}$ 광석 < $CeO_{2}$ 시약 < $Ca(OH)_{2}$ < $La_{2}O_{3}$ 광석 < $La_{2}O_{3}$ 시약의 순서였고, 제철 폐수에서는 $Ca(OH)_{2}$ < $CeO_{2}$ 광석 < $CeO_{2}$ 시약 < $La_{2}O_{3}$ 광석 < $La_{2}O_{3}$ 시약의 순서였다(pH의 영향은 소석회인 경우 pH가 증가할수록 불소제거율이 감소하였다. 세륨화합물과 란탄화합물인 경우는 pH 증가에도 불구하고 불소제거 효율이 증가하는 경향을 보였으나 방류 시 수질조건과 불소제거율을 함께 고려할 때 용액의 적정 pH는 7이 적당하다고 판단된다). 망간제거의 경우, pH 7 이하에서는 소석회가 희토류 화합물보다 우수한 망간제거율을 보였고 pH 10에서는 모든 처리제에 대해서 거의 완벽한 제거특성을 보였다. 총크롬 제거의 경우는 산성 조건에서는 란탄화합물이 가장 높은 불소 제거율을 보였으며 pH 7이상에서는 모든 처리제가 좋은 효율을 보였다.

• 한국치위생학회지
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• 제22권4호
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• pp.231-240
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• 2022

연구목적: 본 연구는 국내에서 시판되고 있는 구강위생용품을 조사하고 구강위생용품에 함유된 불소 농도와 형태에 대한 정보를 제공하기 위해 시행하였다. 연구방법: 국내 시판 구강위생용품을 선택하여 총 67개를 오프라인 시장에서 구매하여 평가하였다. 연구결과: 국내 시판중인 치약 중 1,000 ppm의 불소 농도를 함유한 치약이 59.3%로 가장 많은 비중을 차지했으며, 불소를 함유하지 않은 치약은 3.7%, 1,000 ppm 이하의 불소 농도를 함유한 치약은 33.3%, 1,000 ppm 이상의 불소 농도를 함유한 치약은 3.7%로 나타났다. 선택한 구강양치액 제품의 불소 이온농도를 측정해본 결과, 300 ppm 이내의 불소 이온농도를 나타냈다. 또한 6개의 구강양치액 중 2개의 제품만이 불소 농도를 표기하고 있었다. 구강위생용품의 불소 함량을 나타내는 정보는 제품 종이상자 및 제품 자체에 표기되어 있으나, 거의 모든 표기는 뒷면에 작성되어 있으며 일부 제품에서는 제품 자체에 표기되어 있지 않은 경우도 있었다. 또한 표기된 정보 내용도 제조업체 간, 제조업체 내에서도 상이함을 확인되었다. 결론: 1,000 ppm 이상의 높은 불소 농도를 함유한 치약을 포함한 다양하고 효과적인 불소 농도의 구강위생용품들이 제공됨으로써 소비자들에게 더 넓은 선택의 폭을 제시하면 좋을 것으로 생각된다. 또한, 국내에서 시판 중인 구강위생용품에 대한 소비자에게 제공되는 정보가 다소 적은 것으로 사료되어, 소비자의 구강위생용품 선택에 대한 편의를 위해 명확한 기준 및 정보 표기에 대하여 개선해야 할 것으로 생각된다.

• 대한소아치과학회지
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• 제11권1호
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• pp.151-157
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• 1984

The purpose of this study was to compare the growth-inhibiting effect of sodium fluoride and stannous fluoride on a cariogenic strain of Streptococcus mutans exposed to the different concentration of $SnF_2$ and NaF The result were as follows: 1. The growth rate of the Streptococcus mutans was unaffected by 75 ppmF, slowed by 150 ppmF, and immediately arrested by 300 or 600 ppmF where increments of NaF were added to actively growing 12-hour broth culture. 2. $SnF_2$ slowed the growth rate at 75 ppmF, was to bactericidal initially at 150 and 300 ppmF, and was to totally bactercidal at 600 ppmF. 3. $SnF_2$ has been shown to be more effective than NaF in inhibiting the growth activity of Streptococcus mutans. 4. The inhibitory effect of fluoride compounds on the growth of Streptococcus mutans was increased in the decreased pH at concentration of 600 ppmF.

• Advances in environmental research
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• 제2권1호
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• pp.35-49
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• 2013

Research work on removal of fluoride from water, referred to as water defluoridation, has resulted into the development of a number of technologies over the years but they suffer from either cost or efficiency drawbacks. In this work, enhancement effects of phosphate and silicate on defluoridation of water by low-cost Plaster of Paris (calcined gypsum) were studied. To our knowledge, the influence of silicate on defluoridation was not reported. It was claimed, that the presence of some ions in the treated water samples, was decreasing the fluoride removal since these ions compete the fluoride ions on occupying the available adsorption sites, however, phosphate and silicate ions, from its sodium slats, have enhanced the fluoride % removal, hence, precipitation of calcium-fluoro compounds of these ions can be suggested. Percentage removal of $F^-$ by neat Plaster is 48%, the electrical conductance (EC) curve shows the typical curve of Plaster setting which begins at 20 min and finished at 30 min. The addition of phosphate and silicate ions enhances the removal of fluoride to high extent > 90%. Thermodynamics parameters showed spontaneous fluoride removal by neat Plaster and Plaster-silicate system. The percentage removal with time showed second-order reaction kinetics.

• 대한치과의사협회지
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• 제9권11호
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• pp.679-687
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• 1971