Magnetostriction of Hexagonal HoMnO3 and YMnO3 Single Crystals

Science.gov (United States)

Pavlovskii, N. S.; Dubrovskii, A. A.; Nikitin, S. E.; Semenov, S. V.; Terent'ev, K. Yu.; Shaikhutdinov, K. A.

2018-03-01

We report on the magnetostriction of hexagonal HoMnO3 and YMnO3 single crystals in a wide range of applied magnetic fields (up to H = 14 T) at all possible combinations of the mutual orientations of magnetic field H and magnetostriction Δ L/L. The measured Δ L/L( H, T) data agree well with the magnetic phase diagram of the HoMnO3 single crystal reported previously by other authors. It is shown that the nonmonotonic behavior of magnetostriction of the HoMnO3 crystal is caused by the Ho3+ ion; the magnetic moment of the Mn3+ ion parallel to the hexagonal crystal axis. The anomalies established from the magnetostriction measurements of HoMnO3 are consistent with the phase diagram of these compounds. For the isostructural YMnO3 single crystal with a nonmagnetic rare-earth ion, the Δ L/L( H, T) dependences are described well by a conventional quadratic law in a wide temperature range (4-100 K). In addition, the magnetostriction effect is qualitatively estimated with regard to the effect of the crystal electric field on the holmium ion.

Optical properties of GaS:Ho3+ and GaS:Tm3+ single crystals

International Nuclear Information System (INIS)

Jin, Moon-Seog; Kim, Chang-Dae; Kim, Wha-Tek

2004-01-01

GaS:Ho 3+ and GaS:Tm 3+ single crystals were grown by using the chemical transport reaction method. We measured the optical absorption, the infra-red absorption, and the photoluminescence spectra of the single crystals. The direct and the indirect energy band gaps of the single crystals at 13 K were identified. Infra-red absorption peaks at 6 K appeared in the single crystals. Broad emission bands at 6 K were observed at 464 nm and 580 nm for GaS:Ho 3+ and 462 nm and 581 nm for GaS:Tm 3+ . These broad emission bands were identified as originating from donor-acceptor pair recombinations. Sharp emission peak groups were observed near 435 nm, 495 nm, and 660 nm for GaS:Ho 3+ and near 672 nm for GaS:Tm 3+ . These sharp emission peak groups were identified as being due to the electron transitions between the energy levels of Ho 3+ and Tm 3+ . Especially, white photoluminescence was obtained in the GaS:Ho 3+ single crystal.

Effect of exercise on fluoride metabolism in adult humans: a pilot study.

Science.gov (United States)

V Zohoori, Fatemeh; Innerd, Alison; Azevedo, Liane B; Whitford, Gary M; Maguire, Anne

2015-11-19

An understanding of all aspects of fluoride metabolism is critical to identify its biological effects and avoid fluoride toxicity in humans. Fluoride metabolism and subsequently its body retention may be affected by physiological responses to acute exercise. This pilot study investigated the effect of exercise on plasma fluoride concentration, urinary fluoride excretion and fluoride renal clearance following no exercise and three exercise intensity conditions in nine healthy adults after taking a 1-mg Fluoride tablet. After no, light, moderate and vigorous exercise, respectively, the mean (SD) baseline-adjusted i) plasma fluoride concentration was 9.6(6.3), 11.4(6.3), 15.6(7.7) and 14.9(10.0) ng/ml; ii) rate of urinary fluoride excretion over 0-8 h was 46(15), 44(22), 34(17) and 36(17) μg/h; and iii) rate of fluoride renal clearance was 26.5(9.0), 27.2(30.4), 13.1(20.4) and 18.3(34.9) ml/min. The observed trend of a rise in plasma fluoride concentration and decline in rate of fluoride renal clearance with increasing exercise intensity needs to be investigated in a larger trial. This study, which provides the first data on the effect of exercise with different intensities on fluoride metabolism in humans, informs sample size planning for any subsequent definitive trial, by providing a robust estimate of the variability of the effect.

Optical properties of Mg2+, Yb3+, and Ho3+ tri-doped LiNbO3 crystals

Science.gov (United States)

Dai, Li; Liu, Chun-Rui; Tan, Chao; Yan, Zhe-Hua; Xu, Yu-Heng

2017-04-01

A series of LiNbO3 crystals tri-doped with Mg{}2+, Yb{}3+, and Ho{}3+ are grown by the conventional Czochraski technique. The concentrations of Mg{}2+, Yb{}3+, and Ho{}3+ ions in Mg:Yb:Ho:LiNbO3 crystals are measured by using an inductively coupled plasma atomic emission spectrometry. The x-ray diffraction is proposed to determine the lattice constant and analyze the internal structure of the crystal. The light-induced scattering of Mg:Yb:Ho:LiNbO3 crystal is quantitatively described via the threshold effect of incident exposure energy flux. The exposure energy ({E}{{r}}) is calculated to discuss the optical damage resistance ability. The exposure energy of Mg(7 mol):Yb:Ho:LiNbO3 crystal is 709.17 J/cm2, approximately 425 times higher than that of the Mg(1 mol):Yb:Ho:LiNbO3 crystal in magnitude. The blue, red, and very intense green bands of Mg:Yb:Ho:LiNbO3 crystal are observed under the 980-nm laser excitation to evaluate the up-conversion emission properties. The dependence of the emission intensity on pumping power indicates that the up-conversion emission is a two-photon process. The up-conversion emission mechanism is discussed in detail. This study indicates that Mg:Yb:Ho:LiNbO3 crystal can be applied to the fabrication of new multifunctional photoluminescence devices. Project supported by the National Natural Science Foundation of China (Grant No. 51301055), the Youth Science Fund of Heilongjiang Province, China (Grant No. QC2015061), the Special Funds of Harbin Innovation Talents in Science and Technology Research, China (Grant No. 2015RQQXJ045 ), and the Science Funds for the Young Innovative Talents of Harbin University of Science and Technology, China (Grant No. 201501).

Optical characteristics of BaGa{sub 2}S{sub 4}:Ho{sup 3+} and BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals

Energy Technology Data Exchange (ETDEWEB)

Choe, Sung-Hyu [Chosun University, Kwangju (Korea, Republic of); Jin, Moon-Seog [Dongshin University, Naju (Korea, Republic of); Kim, Wha-Tek [Chonnam National University, Kwangju (Korea, Republic of)

2005-11-15

BaGa{sub 2}S{sub 4}, BaGa{sub 2}S{sub 4}:Ho{sup 3+}, BaGa{sub 2}Se{sub 4}, and BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the single crystals were investigated in the temperature region from 11 K to 300 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Two broad emission bands were observed in the photoluminescence spectra of the single crystals. These bands were attributed to donor-acceptor pair recombinations. Sharp emission peaks were observed in the BaGa{sub 2}S{sub 4}:Ho{sup 3+} and the BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals and were assigned to radiation recombination between split Stark levels of Ho{sup 3+}.

High Power Narrow Linewidth 1.26 Micron Ho-Doped Fiber Amplifier, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — This proposal is for the development of an innovative, high power, and extremely reliable 1.26-micron Ho-doped fluoride fiber amplifier. The proposed fiber amplifier...

High Power Narrow Linewidth 1.26 Micron Ho-Doped Fiber Amplifier, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This proposal is for the development of an innovative, high power, and extremely reliable 1.26-micron Ho-doped fluoride fiber amplifier. The proposed fiber amplifier...

Investigation on Er{sup 3+}/Ho{sup 3+} co-doped silicate glass for ~2 µm fiber lasers

Energy Technology Data Exchange (ETDEWEB)

Liu, Xueqiang; Huang, Feifei; Cheng, Jimeng; Fan, Xiaokang; Gao, Song [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of Chinese Academy of Science, Beijing 100039 (China); Zhang, Junjie [College of Materials Science and Technology, China Jiliang University, Hangzhou 310018 (China); Hu, Lili [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Chen, Danping, E-mail: dpchen2008@aliyun.com [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2015-06-15

A stable Er{sup 3+}/Ho{sup 3+} co-doped lead silicate glass is developed. Luminescent properties are recorded under pumping with 808 and 1550 nm lasers. Energy-transfer mechanism and efficiency are analyzed. Energy-transfer efficiency from Er{sup 3+}:{sup 4}I{sub 13/2} to Ho{sup 3+}:{sup 5}I{sub 7} reaches 93.8% at 3 mol% Ho{sub 2}O{sub 3} doping concentration. Strong luminescence is detected when pumped at 1550 nm because of efficient energy transfer from Er{sup 3+}:{sup 4}I{sub 13/2} to Ho{sup 3+}:{sup 5}I{sub 7}. Peak gain coefficient at 2056 nm is detected as 1.62 cm{sup −1}. The excellent luminescent property and high stability indicate that Er{sup 3+}/Ho{sup 3+} co-doped lead silicate glass can be applied in 2 µm fiber lasers. - Highlights: • Er{sup 3+}/Ho{sup 3+} co-doped silicate glasses with high stability are prepared. • Strong luminescence is detected under pump of 1550 nm lasers owing to efficient energy transfer from Er{sup 3+} to Ho{sup 3+}. • Transfer efficiency is calculated to be 93.8% when Ho{sub 2}O{sub 3} doping concentration is up to 3 mol%. • Gain coefficient peaks at 2056 nm to be 1.62 cm{sup −1}.

Broadband ˜2μm emission in Tm3+/Ho3+ co-doped TeO2-WO3-La2O3 glass

Science.gov (United States)

Li, Kefeng; Wang, Guonian; Zhang, Junjie; Hu, Lili

2010-10-01

In this work, we report the infrared emission properties of Tm 3+/Ho 3+ co-doped TeO 2-WO 3-La 2O 3 (TWL) glass under 808 nm laser excitation. A broad and flat emission from 1600 to 2200 nm corresponding to the Tm 3+ ( 3F 4→ 3H 6) and Ho 3+ ( 5I 7→ 5I 8) emissions is observed. The full width at half maximum (FWHM) of this broadband increases up to a value of ˜370 nm with an optimal [Tm 3+]/[Ho 3+] concentration ratio. The energy transfer processes of Tm 3+↔Ho 3+ are analyzed and the results show that energy transfer between Tm 3+ and Ho 3+ plays an important role in the luminescence mechanism. The OH - influence on the broadband emission is also discussed. These results indicate that Tm 3+-Ho 3+ co-doped TWL glass could be a promising material for widely tunable laser or broadband amplifier applications.

Tuning into single-band red upconversion luminescence in Yb(3+)/Ho(3+) activated nano-glass-ceramics through Ce(3+) doping.

Science.gov (United States)

Chen, Daqin; Zhou, Yang; Wan, Zhongyi; Ji, Zhenguo; Huang, Ping

2015-03-28

Yb(3+)/Ho(3+) activated glass ceramics containing β-YF3 nanocrystals were successfully fabricated. The green ((5)S2/(5)F4→(5)I8) upconversion emission is dominant in the glass ceramics and is about 160 times stronger than that of the precursor glass, resulting from the partition of lanthanide activators into a low-phonon-energy crystalline lattice and the subsequent low probability of multi-phonon nonradiative relaxation from the (5)S2/(5)F4 and (5)I6 states to the lower ones. Upon the introduction of Ce(3+) ions into nano-glass-ceramics, two efficient cross-relaxation processes between Ho(3+) and Ce(3+), i.e., Ho(3+):(5)S2/(5)F4 + Ce(3+):(2)F5/2→Ho(3+):(5)F5 + Ce(3+):(2)F7/2 and Ho(3+):(5)I6 + Ce(3+):(2)F5/2→Ho(3+):(5)I7 + Ce(3+):(2)F7/2, are demonstrated to greatly suppress the population of the green-emitting (5)S2/(5)F4 state and to enhance the population of the red-emitting (5)F5 one, leading to the intense single-band red UC radiation of Ho(3+).

Upconversion dynamics in Yb3+-Ho3+-doped fluoroindate glasses

International Nuclear Information System (INIS)

Martin, I.R.; Rodriguez, V.D.; Lavin, V.; Rodriguez-Mendoza, U.R.

1998-01-01

The mechanisms and dynamics of the upconversion emissions in Yb 3+ -Ho 3+ -doped fluoroindate glasses by exciting at 975 nm have been analysed. The upconversion efficiencies have been measured as a function of temperature in the range from 12 to 295 K. The temporal evolution of the 545- and 650-nm upconversion emissions obtained under flash excitation at 975 nm in codoped samples with 2.25 mol.% of Yb 3+ and 0.75 mol.% of Ho 3+ cannot be described using the energy migration model. This indicates that at this concentration of Yb 3+ the rapid migration regimen between these ions has not been reached. A model is proposed in order to explain the temporal evolution of these emissions taking into account energy migration between donors and backtransfer processes. (orig.)

A Ho(III) potentiometric polymeric membrane sensor based on a new four dentate neutral ion carrier.

Science.gov (United States)

Zamani, Hassan Ali; Zanganeh-Asadabadi, Abbas; Rohani, Mitra; Zabihi, Mohammad Saleh; Fadaee, Javad; Ganjali, Mohammad Reza; Faridbod, Farnoush; Meghdadi, Soraia

2013-03-01

In this research, we report a new Ho(3+)-PVC membrane electrode based on N-(4,5-dimethyl-2-(picolinamido)phenyl)picolinamide (H(2)Me(2)bpb) as a suitable ion carrier. Poly vinylchloride (PVC)-based membrane composed of H(2)Me(2)bpb with oleic acid (OA) as anionic additives, and o-nitrophenyloctyl ether (NPOE) as plasticized solvent mediator. The sensor exhibits a Nernstian slope of 20.1 ± 0.2 mV decade(-1) over the concentration range of 1.0 × 10(-6) to 1.0 × 1(-2) mol L(-1), and a detection limit of 5.0 × 10(-7) mol L(-1) of Ho(3+) ions. The potentiometric response of the sensor is independent of the solution pH in the range of 3.5-9.4. It has a very short response time, in the whole concentration range (titration of Ho(3+) ion solutions in certified reference materials, alloy samples and for the determination of the fluoride ion in two mouthwash preparations. Copyright © 2012 Elsevier B.V. All rights reserved.

Hydrothermal synthesis, characterization and up/down-conversion luminescence of barium rare earth fluoride nanocrystals

International Nuclear Information System (INIS)

Jia, Li-Ping; Zhang, Qiang; Yan, Bing

2014-01-01

Graphical abstract: Lanthanide ions doped bare earth rare earth fluoride nanocrystals are synthesized by hydrothermal technology and characterized. The down/up-conversion luminescence of them are discussed. - Highlights: • Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is used for synthesis. • Barium rare earth fluoride nanocrystals are synthesized comprehensively. • Luminescence for down-conversion and up-conversion are obtained for these systems. - Abstract: Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is developed to synthesize barium rare earth fluorides nanocrystals (OA = oleylamine, EDA = ethylenediamine, O-A = oleic acid and LO-A = linoleic acid). They are presented as BaREF 5 (RE = Ce, Pr, Nd, Eu, Gd, Tb, Dy, Y, Tm, Lu) and Ba 2 REF 7 (RE = La, Sm, Ho, Er, Yb). The influence of reaction parameters (rare earth species, hydrothermal system and temperature) is checked on the phase and shape evolution of the fluoride nanocrystals. It is found that reaction time and temperature of these nanocrystals using EDA (180 °C, 6 h) is lower than those of them using OA (220 °C, 10 h). The photoluminescence properties of these fluorides activated by some rare earth ions (Nd 3+ , Eu 3+ , Tb 3+ ) are studied, and especially up-conversion luminescence of the four fluoride nanocrystal systems (Ba 2 LaF 7 :Yb, Tm(Er), Ba 2 REF 7 :Yb, Tm(Er) (RE = Gd, Y, Lu)) is observed

Lattice effects in HoVo3 single crystal

International Nuclear Information System (INIS)

Sikora, M.; Marquina, C.; Ibarra, M.R.; Nugroho, A.A.; Palstra, T.T.M.

2007-01-01

We report the study of lattice effects in the Mott insulator HoVO 3 performed by means of linear thermal expansion on a single crystal in the temperature range 10-290 K. The holmium orthovanadate HoVO 3 reveals gradual orbital ordering (OO) below T OO =200 K and orders antiferromagnetically at T N =113 K. A first-order structural phase transition takes place at T S ∼38 K, which is probably accompanied by change of the OO type and hence the type of antiferromagnetic spin ordering

Tunable multicolor and white-light upconversion luminescence in Yb3+/Tm3+/Ho3+ tri-doped NaYF4 micro-crystals.

Science.gov (United States)

Lin, Hao; Xu, Dekang; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

2015-09-01

NaYF4 micro-crystals with various concentrations of Yb(3+) /Tm(3+) /Ho(3+) were prepared successfully via a simple and reproducible hydrothermal route using EDTA as the chelating agent. Their phase structure and surface morphology were studied using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns revealed that all the samples were pure hexagonal phase NaYF4. SEM images showed that Yb(3+)/Tm(3+)/Ho(3+) tri-doped NaYF4 were hexagonal micro-prisms. Upconversion photoluminescence spectra of Yb(3+)/Tm(3+)/Ho(3+) tri-doped NaYF4 micro-crystals with various dopant concentrations under 980 nm excitation with a 665 mW pump power were studied. Tunable multicolor (purple, purplish blue, yellowish green, green) and white light were achieved by simply adjusting the Ho(3+) concentration in 20%Yb(3+)/1%Tm(3+)/xHo(3+) tri-doped NaYF4 micro-crystals. Furthermore, white-light emissions could be obtained using different pump powers in 20%Yb(3+)/1%Tm(3+)/1%Ho(3+) tri-doped NaYF4 micro-crystals at 980 nm excitation. The pump power-dependent intensity relationship was studied and relevant energy transfer processes were discussed in detail. The results suggest that Yb(3+)/Tm(3+) Ho(3+) tri-doped NaYF4 micro-crystals have potential applications in optoelectronic devices such as photovoltaic, plasma display panel and white-light-emitting diodes. Copyright © 2014 John Wiley & Sons, Ltd.

The reactions of SO3 with HO2 radical and H2O...HO2 radical complex. Theoretical study on the atmospheric formation of HSO5 and H2SO4.

Science.gov (United States)

Gonzalez, Javier; Torrent-Sucarrat, Miquel; Anglada, Josep M

2010-03-07

The influence of a single water molecule on the gas-phase reactivity of the HO(2) radical has been investigated by studying the reactions of SO(3) with the HO(2) radical and with the H(2)O...HO(2) radical complex. The naked reaction leads to the formation of the HSO(5) radical, with a computed binding energy of 13.81 kcal mol(-1). The reaction with the H(2)O...HO(2) radical complex can give two different products, namely (a) HSO(5) + H(2)O, which has a binding energy that is computed to be 4.76 kcal mol(-1) more stable than the SO(3) + H(2)O...HO(2) reactants (Delta(E + ZPE) at 0K) and an estimated branching ratio of about 34% at 298K and (b) sulfuric acid and the hydroperoxyl radical, which is computed to be 10.51 kcal mol(-1) below the energy of the reactants (Delta(E + ZPE) at 0K), with an estimated branching ratio of about 66% at 298K. The fact that one of the products is H(2)SO(4) may have relevance in the chemistry of the atmosphere. Interestingly, the water molecule acts as a catalyst, [as it occurs in (a)] or as a reactant [as it occurs in (b)]. For a sake of completeness we have also calculated the anharmonic vibrational frequencies for HO(2), HSO(5), the HSO(5)...H(2)O hydrogen bonded complex, H(2)SO(4), and two H(2)SO(4)...H(2)O complexes, in order to help with the possible experimental identification of some of these species.

Color tunable emission through energy transfer from Yb3+ co-doped SrSnO3: Ho3+ perovskite nano-phosphor

Science.gov (United States)

Jain, Neha; Singh, Rajan Kr.; Sinha, Shriya; Singh, R. A.; Singh, Jai

2018-04-01

First time color tunable lighting observed from Ho3+ and Yb3+ co-doped SrSnO3 perovskite. Down-conversion and up-conversion (UC) photoluminescence emission spectra were recorded to understand the whole mechanism of energy migration between Ho3+ and Yb3+ ions. The intensity of green and red emission varies with Yb3+ doping which causes multicolour emissions from nano-phosphor. The intensity of UC red emission (654 nm) obtained from 1 at.% Ho3+ and 3 at.% Yb3+ co-doped nano-phosphor is nine times higher than from 1 at.% Ho3+ doped SrSnO3 nano-phosphor. Enhanced brightness of 654 nm in UC process belongs in biological transparency window so that it might be a promising phosphor in the bio-medical field. Moreover, for the other Yb3+ co-doped nano-phosphor, Commission Internationale de l'Éclairage chromaticity co-ordinates were found near the white region and their CCT values lie in the range 4900-5100 K indicating cool white. Decay time was measured for 545 nm emission of Ho3+ ion found in 7.652 and 8.734 µs at 355 nm excitation. The variation in lifetime was observed in ascending order with increasing Yb3+ concentration which supports PL emission spectra observation that with increasing Yb3+ concentration, rate of transition has changed. These studies reveal that Ho3+ and Yb3+ co-doped phosphor is useful for fabrication of white LEDs.

Fluoride release from fluoride varnishes under acidic conditions.

Science.gov (United States)

Lippert, F

2014-01-01

The aim was to investigate the in vitro fluoride release from fluoride varnishes under acidic conditions. Poly(methyl methacrylate) blocks (Perspex, n=3 per group) were painted with 80 ± 5 mg fluoride varnish (n=10) and placed into artificial saliva for 30 min. Then, blocks were placed into either 1% citric acid (pH 2.27) or 0.3% citric acid (pH 3.75) solutions (n=3 per solution and varnish) for 30 min with the solutions being replaced every 5 min. Saliva and acid solutions were analyzed for fluoride content. Data were analyzed using three-way ANOVA (varnish, solution, time). The three-way interaction was significant (p>0.0001). Fluoride release and release patterns varied considerably between varnishes. Fluoride release in saliva varied by a factor of more than 10 between varnishes. Some varnishes (CavityShield, Nupro, ProFluorid, Vanish) showed higher fluoride release in saliva than during the first 5 min of acid exposure, whereas other varnishes (Acclean, Enamel-Pro, MI Varnish, Vella) showed the opposite behavior. There was little difference between acidic solutions. Fluoride release from fluoride varnishes varies considerably and also depends on the dissolution medium. Bearing in mind the limitations of laboratory research, the consumption of acidic drinks after fluoride varnish application should be avoided to optimize the benefit/risk ratio.

Formation enthalpies of LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) interlanthanide perovskites

Energy Technology Data Exchange (ETDEWEB)

Qi, Jianqi [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Laboratory of High Energy Density Physics of Ministry of Education, Sichuan University, Chengdu 610064 (China); Guo, Xiaofeng [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); Mielewczyk-Gryn, Aleksandra [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); Faculty of Applied Physics and Mathematics, Department of Solid State Physics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.edu [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States)

2015-07-15

High-temperature oxide melt solution calorimetry using 3Na{sub 2}O·MoO{sub 3} at 802 °C was performed for interlanthanide perovskites LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) and lanthanide oxides (La{sub 2}O{sub 3}, Ho{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, Tm{sub 2}O{sub 3} and Yb{sub 2}O{sub 3}). The enthalpies of formation of these interlanthanide perovskites from binary lanthanide oxides at room temperature (25 °C) were determined to be −8.3±3.4 kJ/mol for LaHoO{sub 3}, −9.9±3.0 kJ/mol for LaErO{sub 3}, −10.8±2.7 kJ/mol for LaTmO{sub 3} and −12.3±2.9 kJ/mol for LaYbO{sub 3}. There is a roughly linear relationships between these enthalpy values and the tolerance factor for these and for other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites, confirming that the distortion of the perovskites as results from ionic radius difference of A-site and B-site cations, is the main factor determining the stability of these compounds. - Graphical abstract: A linear relationship between the enthalpy of formation and the tolerance factor for interlanthanide LaLn'O{sub 3} (Ln'=Ho, Er, Tm, and Yb) and other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites. - Highlights: • Interlanthanide perovskites were synthesized by solid state reactions. • Their enthalpies of formation were measured by oxide melt solution calorimetry. • ΔH{sub f,ox} shows a linear relationship with tolerance factor.

Magnetic and crystallographic properties of HoCo3B2

International Nuclear Information System (INIS)

Caspi, E.N.; Dubman, M.; Ettedgui, H.; Shaked, H.; Short, S.; Jorgensen, J.D.

2005-01-01

AC-susceptibility measurements for HoCo 3 B 2 show paramagnetism below room temperature and a small, and large anomalies at 150 and 10K, respectively. Neutron powder diffraction measurements show a ferromagnetic order below 10K, where the ferromagnetic Ho and Co sublattices are ferromagnetically coupled. The magnetic axis direction is perpendicular to the c axis. The observed magnitudes of the magnetic moments at 4.5K are 5.08(4) and 0.11(2) μ B for Ho and Co, respectively. No long range magnetic order was detected above 10K

Concentration effect of Tm3+ on cathodoluminescence properties of SiO2: Tm3+ and SiO2:Ho3+, Tm3+ systems

CSIR Research Space (South Africa)

Dhlamini, MS

2012-05-01

Full Text Available .physb.2011.09.091 Concentration effect of Tm3+ on cathodoluminescence properties of SiO2: Tm 3+ and SiO2:Ho 3+, Tm3+ systems M.S. Dhlamini, G.H. Mhlongo, H.C. Swart, O.M. Ntwaeaborwa, K.T. Hillie ABSTRACT: Cathodoluminescence (CL) properties of Si...O2 powders activated with thulium (Tm3+) and holmium (Ho3+) ions prepared by a sol–gel process were investigated. Different molar concentrations of Tm3+ co-doped with Ho3+ were studied. The 460 nm peak was monitored and the influence of the beam...

Electronic transitions of Ho in Pb2Sr2HoCu3O8 observed by inelastic neutron scattering

International Nuclear Information System (INIS)

Soderholm, L.; Loong, C.; Xue, J.S.; Hammonds, J.P.; Greedan, J.E.; Maric, M.

1993-01-01

The electronic behavior of the 5 I 8 Russell Saunders ground multiplet of Ho 3+ in Pb 2 Sr 2 HoCu 3 O 8 has been investigated using inelastic neutron scattering. We observe ten peaks in the excitation spectra that are associated with crystal field transitions. The peaks are only slightly broader than expected from instrument resolution, indicating that there are no strong interactions between the local Ho f states and the CuO conduction states. Comparing the energies and intensities of the experimental peaks with those expected from modeling convinces us that there are at least three states populated at the temperature of our experiment (15 K), making the assignments of transitions very difficult in the absence of further data

Broad band and enhanced photocatalytic behaviour of Ho3+-doped Bi2O3 micro-rods

Science.gov (United States)

Prasad, Neena; Karthikeyan, Balasubramanian

2018-06-01

Band-gap-tuned Bi2O3 micro-rods were synthesized using simple co-precipitation method by doping 5 wt% Ho3+ to mitigate the concentration of toxic dye from the polluted water using it as a photocatalyst. Structure and morphology of the prepared samples were identified using powder X-ray diffraction technique and scanning electron microscopy (SEM). Elemental composition and chemical state of the prepared samples were analyzed from the X-ray photoelectron spectroscopy (XPS). Considerable absorption in IR region was observed for Ho3+ doped Bi2O3 due to the electronic transitions of 5I8→5F4, 5I8→5F5, and 5I8→5I5, 5I6. The excellent ultra-violet (UV), white and infrared light (IR)-driven photocatalytic activity were suggested for pure and doped Bi2O3 samples. Ho3+-doped Bi2O3 micro-rods exhibits a better photocatalytic activity under white light irradiation. The consequence of the bandgap and the synergetic effect of Ho3+ and Bi2O3 on the photocatalytic degradation of MB were investigated.

IUPAC-NIST Solubility Data Series. 100. Rare Earth Metal Fluorides in Water and Aqueous Systems. Part 3. Heavy Lanthanides (Gd–Lu)

Energy Technology Data Exchange (ETDEWEB)

Mioduski, Tomasz [Institute of Nuclear Chemistry and Technology, 03195 Warszawa (Poland); Gumiński, Cezary, E-mail: cegie@chem.uw.edu.pl [Department of Chemistry, University of Warsaw, 02093 Warszawa (Poland); Zeng, Dewen, E-mail: dewen-zeng@hotmail.com [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

2015-06-15

This is the third part of the volume devoted to solubility data for the rare earth metal (REM) fluorides in water and in aqueous ternary and multicomponent systems. It covers experimental results of trivalent fluorides of Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu (so-called heavy lanthanides), since no quantitative data on solubilities of TbF{sub 4} and YbF{sub 2} (the most stable compounds at these valencies) are available. The related literature has been covered through the end of 2014. Compilations of all available papers with the solubility data are introduced for each REM fluoride with a corresponding critical evaluation. Every such assessment contains a collection of all solubility results in aqueous solution, a selection of suggested solubility data, a solubility equation, and a brief discussion of the multicomponent systems. Only simple fluorides (no complexes or double salts) are treated as the input substances in this report. General features of the systems, such as nature of the equilibrium solid phases, solubility as a function of temperature, influence of ionic strength, solution pH, mixed solvent medium on the solubility, quality of the solubility results, and the solubility as a function of REM atomic number, have already been presented in Part 1 of the volume.

Spectroscopic investigation of 2.0 μm emission in Ho3+-doped fluoroindate glasses

International Nuclear Information System (INIS)

Oliveira, S L; Bell, M J V; Florez, A; Nunes, L A O

2006-01-01

In this paper we report the optical characterization of Ho 3+ -doped fluoroindate glasses with the following composition (40 - x)InF 3 -20SrF 2 -16BaF 2 -20ZnF 2 -2GdF 3 -2NaF-xHoF 3 with x = 1.0, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 8.0 and 9.0 mol%. This investigation was done by means of absorption, fluorescence and lifetime measurements. The phenomenological intensity parameters Ω λ (λ = 2, 4, 6) were calculated using the standard Judd-Ofelt theory. In order to evaluate potential applications of the 5 I 7 → 5 I 8 Ho 3+ emission at 2.0 μm, the radiative lifetime, total transition rate and emission cross section were determined. The effect of Ho 3+ concentration on the fluorescence intensity and lifetimes was analysed. It was concluded that the non-radiative losses of the 5 I 7 level are mainly due to energy migration among Ho 3+ ions followed by energy transfer to quenching impurities

Magnetic excitations in Ho2Co17 and Ho2Fe17

International Nuclear Information System (INIS)

Clausen, K.N.

1981-01-01

The low energy part ( 2 Co 17 and Ho 2 Fe 17 have been measured along the three high symmetry directions at a temperature of 4.2 K, using the inelastic neutron scattering technique. The resulting magnon dispersion relations have been interpreted using linear spin wave theory with a Hamiltonian including single ion crystal field anisotropy and isotropic exchange between spatially well localized spins. The R 2 T 17 structure contains two different Ho sites, with the same point symmetry, and from the spin wave results it was concluded that the crystal field anisotropy of the two Ho sites in both Ho 2 Co 17 and Ho 2 Fe 17 were identical. The deduced crystal field parameters for Ho 2 Fe 17 were slightly larger than for Ho 2 Co 17 , and the parameters were of the same order of magnitude as for pure Ho. For Ho 2 Fe 17 the Fe-Fe exchange was found to be anisotropic, and for both compounds the magnetic ordering temperatures of 1178 K for Ho 2 Co 17 and 335 K for Ho 2 Fe 17 were determined by the strong positive 3d-3d exchange. (Auth.)

Antiperovskite nitridophosphate oxide Ho{sub 3}[PN{sub 4}]O by high-pressure metathesis

Energy Technology Data Exchange (ETDEWEB)

Kloss, Simon D.; Weidmann, Niels; Schnick, Wolfgang [Department of Chemistry, University of Munich (LMU), Butenandtstrasse 5-13, 81377, Munich (Germany)

2017-04-03

Rare-earth nitridophosphates are a recently discovered class of materials, which are accessible by high-pressure metathesis. Antiperovskite-type Ho{sub 3}[PN{sub 4}]O was synthesized from HoF{sub 3}, LiPN{sub 2}, Li{sub 3}N, and Li{sub 2}O at 5 GPa and ca. 1025 C by this method and the multianvil technique. Ho{sub 3}[PN{sub 4}]O contains rarely observed isolated PN{sub 4} tetrahedra and can be derived by the hierarchical substitution of the ABX{sub 3} perovskite, in which Ho occupies the X positions, O occupies the B position, and the PN{sub 4} tetrahedra occupy the A position. The structure was refined on the basis of powder diffraction data [I4/mcm, a = 6.36112(3), c = 10.5571(1) Aa, Z = 4, R{sub wp} = 0.04, R{sub Bragg} = 0.01, χ{sup 2} = 2.275] starting from the structural model of isotypic Gd{sub 3}[SiN{sub 3}O]O. To characterize Ho{sub 3}[PN{sub 4}]O, elemental analyses were performed through energy-dispersive X-ray spectroscopy (EDX) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Ho{sub 3}[PN{sub 4}]O is paramagnetic down to low temperatures with μ{sub eff} = 10.43(1) μ{sub B} and a Curie temperature (Θ) of 0.11(4) K. It shows the optical characteristics of Ho{sup 3+} ions and vibrations corresponding to isolated PN{sub 4} tetrahedra. On the basis of DFT calculations [generalized gradient approximation (GGA)], Ho{sub 3}[PN{sub 4}]O has an indirect band gap of 1.87 eV. We demonstrate the versatility of high-pressure metathesis by attaining the low end of the P/N atomic ratio κ = 1/4. This confirms the previous assumption that rare-earth nitridophosphates with κ = 1/2 to 1/4 are feasible by this method. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

2.05 xB5m emission properties and energy transfer mechanism of germanate glass doped with Ho3+, Tm3+, and Er3+

Science.gov (United States)

Xu, Rongrong; Wang, Meng; Tian, Ying; Hu, Lili; Zhang, Junjie

2011-03-01

A new GeO2-Ga2O3-Na2O-BaO-La2O3 germanate glass doped with Ho2O3, Tm2O3, and Er2O3 has been investigated for application as a laser material at the 2 μm region. The spectroscopic properties and energy transfer mechanisms of Ho3+ sensitized by Tm3+ and Er3+ are analyzed. Based on the measurement of absorption spectra, the Judd-Ofelt intensity parameters, radiation emission probability, branching ratio, and lifetime of Ho3+ are calculated to evaluate the spectroscopic properties. The maximum value of emission cross section of Ho3+ around 2.05 μm is 8.003×10-21 cm2, which indicates that the germanate glass may provide high gain as a good medium in high-power level laser system. It is also found that the 2.05 μm emission of Ho3+:5I7→5I8 can be greatly enhanced by adding the proper amount of Er2O3 and Tm2O3 under excitation at 808 nm. With the large energy transfer coefficient, the high efficient energy transfer process among Ho3+, Tm3+, and Er3+ ions is proven.

Technical note: Evaluation of the simultaneous measurements of mesospheric OH, HO2, and O3 under a photochemical equilibrium assumption - a statistical approach

Science.gov (United States)

Kulikov, Mikhail Y.; Nechaev, Anton A.; Belikovich, Mikhail V.; Ermakova, Tatiana S.; Feigin, Alexander M.

2018-05-01

This Technical Note presents a statistical approach to evaluating simultaneous measurements of several atmospheric components under the assumption of photochemical equilibrium. We consider simultaneous measurements of OH, HO2, and O3 at the altitudes of the mesosphere as a specific example and their daytime photochemical equilibrium as an evaluating relationship. A simplified algebraic equation relating local concentrations of these components in the 50-100 km altitude range has been derived. The parameters of the equation are temperature, neutral density, local zenith angle, and the rates of eight reactions. We have performed a one-year simulation of the mesosphere and lower thermosphere using a 3-D chemical-transport model. The simulation shows that the discrepancy between the calculated evolution of the components and the equilibrium value given by the equation does not exceed 3-4 % in the full range of altitudes independent of season or latitude. We have developed a statistical Bayesian evaluation technique for simultaneous measurements of OH, HO2, and O3 based on the equilibrium equation taking into account the measurement error. The first results of the application of the technique to MLS/Aura data (Microwave Limb Sounder) are presented in this Technical Note. It has been found that the satellite data of the HO2 distribution regularly demonstrate lower altitudes of this component's mesospheric maximum. This has also been confirmed by model HO2 distributions and comparison with offline retrieval of HO2 from the daily zonal means MLS radiance.

Spectroscopic properties of Ho{sup 3+}-doped K-Sr-Al phosphate glasses

Energy Technology Data Exchange (ETDEWEB)

Linganna, K.; Rathaiah, M.; Venkatramu, V. [Yogi Vemana University, Department of Physics, Kadapa (India); Jayasankar, C.K. [Sri Venkateswara University, Department of Physics, Tirupati (India)

2014-05-15

Trivalent holmium-doped K-Sr-Al phosphate glasses (P{sub 2}O{sub 5}-K{sub 2}O-SrO-Al{sub 2}O{sub 3}-Ho{sub 2}O{sub 3}) were prepared, and their spectroscopic properties have been evaluated using absorption, emission, and excitation measurements. The Judd-Ofelt theory has been used to derive spectral intensities of various absorption bands from measured absorption spectrum of 1.0 mol% Ho{sub 2}O{sub 3}-doped K-Sr-Al phosphate glass. The Judd-Ofelt intensity parameters (Ω{sub λ}, x 10{sup -20} cm{sup 2}) have been determined of the order of Ω{sub 2} = 11.39, Ω{sub 4} = 3.59, and Ω{sub 6} = 2.92, which in turn used to derive radiative properties such as radiative transition probability, radiative lifetime, branching ratios, etc. for excited states of Ho{sup 3+} ions. The radiative lifetimes for the {sup 5}F{sub 4}, {sup 5}S{sub 2}, and {sup 5}F{sub 5} levels of Ho{sup 3+} ions are found to be 169, 296, and 317 μs, respectively. The stimulated emission cross-section for 2.05-μm emission was calculated by the McCumber theory and found to be 9.3 x 10{sup -21} cm{sup 2}. The wavelength-dependent gain coefficient with population inversion rate has been evaluated. The results obtained in the titled glasses are discussed systematically and compared with other Ho{sup 3+}-doped systems to assess the possibility for visible and infrared device applications. (orig.)

Application of N-Quinoline-2-carboxamido-8-aminoquinoline in Fabrication of a Ho(III-PVC Membrane Sensor

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Hassan Ali Zamani

2011-01-01

Full Text Available The N-quinoline-2-carboxamido-8-aminoquinoline (QCA was used as a suitable ion carrier in the construction of a Ho(III PVC-based membrane sensor. This sensor demonstrated good selectivity and sensitivity towards the holmium ion for a broad variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The proposed electrode exhibits a linear dynamic range between 1.0×10-6 and 1.0×10-2 M, with a near Nernstian slope of 20.4±0.3 mV per decade and a detection limit of 4.2×10-7 M. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride, 56% nitrobenzene, 2% sodium tetraphenyl borate, 10% oleic acid and 2% QCA. The potentiometric response of the constructed electrode is pH independent in the range of 2.4-7.4. The sensor possesses the advantages of short conditioning time, fast response time (∼ 5 s and especially, good selectivity towards transition and heavy metal and some mono, di and trivalent cations. The Ho3+ sensor was successfully applied as an indicator electrode in the potentiometric titration of Ho(III ions with EDTA. The electrode was also used for the determination of Ho3+ ions in mixtures of different ions and the determination of the fluoride ion in mouth wash solutions.

Magnetocaloric properties of the hexagonal HoMnO{sub 3} single crystal revisited

Energy Technology Data Exchange (ETDEWEB)

Balli, M., E-mail: Mohamed.balli@Usherbrooke.ca [Regroupement québécois sur les matériaux de pointe, Département de physique, Université de Sherbrooke, QC, Canada J1K 2R1 (Canada); Roberge, B.; Vermette, J.; Jandl, S. [Regroupement québécois sur les matériaux de pointe, Département de physique, Université de Sherbrooke, QC, Canada J1K 2R1 (Canada); Fournier, P. [Regroupement québécois sur les matériaux de pointe, Département de physique, Université de Sherbrooke, QC, Canada J1K 2R1 (Canada); Canadian Institute for Advanced Research, Toronto, Ontario, Canada M5G 1Z8 (Canada); Gospodinov, M.M. [Institute of Solid State Physics, Bulgarian Academy of Science, Sofia 1184 (Bulgaria)

2015-12-01

Magnetic and magnetocaloric properties of the hexagonal HoMnO{sub 3} single crystal have been revisited. It was found that the magnetocaloric effect shown by HoMnO{sub 3} strongly depends on the crystal orientation in respect to the applied magnetic field. Consequently, a large thermal effect can be induced by spinning the single crystal HoMnO{sub 3} around the a (or b) axis in a constant magnetic field instead of the conventional magnetization–demagnetization process. Under 7 T, the maximum rotating entropy change was evaluated to be about 8 J/kg K. The associated adiabatic temperature change reaches a value of about 5 K. These values are comparable to those of the other oxides exhibiting a large rotating magnetocaloric effect. The presence of both conventional and rotating thermal effects makes the hexagonal HoMnO{sub 3} more interesting from a practical point of view.

High-power and highly efficient diode-cladding-pumped holmium-doped fluoride fiber laser operating at 2.94 microm.

Science.gov (United States)

Jackson, Stuart D

2009-08-01

A high-power diode-cladding-pumped Ho(3+), Pr(3+)-doped fluoride glass fiber laser is demonstrated. The laser produced a maximum output power of 2.5 W at a slope efficiency of 32% using diode lasers emitting at 1,150 nm. The long-emission wavelength of 2.94 microm measured at maximum pump power, which is particularly suited to medical applications, indicates that tailoring of the proportion of Pr(3+) ions can provide specific emission wavelengths while providing sufficient de-excitation of the lower laser level.

Development of technology and equipment for manufacturing fluorides rare-earths via non-aqueous method

International Nuclear Information System (INIS)

Chatalov, V.V.; Kozlov, O.I.; Machirev, V.P.; Zvonarev, E.N.

1998-01-01

fluorination of was at the least 99,9% and the content of the main material RE F 3 (RE- Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm and Lu) at the least 99,95%. The process for anhydrous fluorides production required reactors of various types in accordance to the given capacity. In a vertical apparatus with vibroplate, the process goes in a counterflow manner and the working temperature reaches 850 deg C. The apparatus with an endless screw stirring produces up to 15 kg / h RE-fluorides by the gaseous method. The third type is the reactor with a conveyer worm stirring of the anhydrous fluorides manufacture. The capacity of the reactor reaches over 50 kg / h of anhydrous RE-fluorides

Optical spectroscopy and luminescence properties of Ho3+ doped zinc fluorophosphate (ZFP) glasses for green luminescent device applications

Science.gov (United States)

Reddy Prasad, V.; Damodaraiah, S.; Ratnakaram, Y. C.

2018-04-01

Ho3+ doped zinc fluorophosphate (ZFP) glasses with molar chemical compositions, (60-x) NH4H2PO4+20ZnO+10BaF2+10NaF+xHo2O3 (where x = 0.1, 0.3, 0.5, 1.0 and 1.5 mol%) were prepared by melt quenching technique. These glasses were characterized through physical, structural, optical, excitation, luminescence and decay curve analysis. From the absorption spectra, spectral intensities (fexp and fcal), Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6), radiative transition probabilities (AT), radiative lifetimes (τR) and branching ratios (βR) were evaluated for all Ho3+ doped ZFP glass matrices. From the photoluminescence spectra, peak stimulated emission cross-sections (σP) were calculated for all Ho3+ doped ZFP glasses. The Ho3+ doped ZFP glasses show strong green emission at 545 nm and red emission at 656 nm under excitation, 450 nm. The measured lifetimes (τmeas) of (5S2)5F4 level of Ho3+ doped ZFP glasses were obtained from decay profiles. The CIE color coordinates of Ho3+ doped ZFP glasses were calculated from emission spectra and 1.0 mol% of Ho3+ doped ZFP glass matrix gives green emission. Hence, these results confirm that the Ho3+ doped ZFP glasses could be considered as a promising candidate for visible green laser applications.

Optical and Physical Investigations of Lanthanum Bismuth Borate glasses doped with Ho2O3

Science.gov (United States)

Ramesh, P.; Jagannath, G.; Eraiah, B.; Kokila, M. K.

2018-02-01

Holmium doped 10La2O3-15Bi2O3-(75-x) B2O3 (Ho3+: LBB) glasses have been prepared by melt quench technique and the impact of holmium ions concentration on optical and physical properties of present glasses have been examined. Ho3+ dependent density, molar volume, refractive index, rare earth ion concentration, polaron radius, inter ionic distance, field strength and energy band gap are calculated and tabulated. Amorphous nature of the all glasses has been confirmed by XRD patterns. The room temperature (RT) Uv-Vis absorption spectrum doped with 1 mol% of Ho2O3 exhibit eight prominent bands centred at 895, 641, 537, 486, 472, 467, 451 and 416 due to transition between ground state to various excited states. The results show that, the density is increases and molar volume of the glasses is decreases with an increase in Ho2O3 concentration and consequently generate more non-bridging oxygen (NBOs) in the glass matrix. The Urbach energy is increases with holmium concentration which exemplifies the degree of disorder present in the LBB glasses. The considerable increase in field strength observed in present glasses is attributed to occurrence of strong bridge between Ho3+ and B- ions and this strong bridge is possibly due to the displacement between Ho3+ and oxygen atoms which are generated from the conversion BO3-BO4 units.

Ho2O3 additive effects on BaTiO3 ceramics microstructure and dielectric properties

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Paunović Vesna

2012-01-01

Full Text Available Doped BaTiO3-ceramics is very interesting for their application as PTCR resistors, multilayer ceramic capacitors, thermal sensors etc. Ho doped BaTiO3 ceramics, with different Ho2O3 content, ranging from 0.01 to 1.0 wt% Ho, were investigated regarding their microstructural and dielectric characteristics. The samples were prepared by the conventional solid state reaction and sintered at 1320° and 1380°C in an air atmosphere for 4 hours. The grain size and microstructure characteristics for various samples and their phase composition was carried out using a scanning electron microscope (SEM equipped with EDS system. SEM analysis of Ho/BaTiO3 doped ceramics showed that in samples doped with a rare-earth ions low level, the grain size ranged from 20-30μm, while with the higher dopant concentration the abnormal grain growth is inhibited and the grain size ranged between 2- 10μm. Dielectric measurements were carried out as a function of temperature up to 180°C. The low doped samples sintered at 1380°C, display the high value of dielectric permittivity at room temperature, 2400 for 0.01Ho/BaTiO3. A nearly flat permittivity-response was obtained in specimens with higher additive content. Using a Curie-Weiss low and modified Curie-Weiss low the Curie constant (C, Curie temperature (Tc and a critical exponent of nonlinearity (γ were calculated. The obtained value of γ pointed out that the specimens have almost sharp phase transition. [Projekat Ministarstva nauke Republike Srbije, br. 172057: Directed synthesis, structure and properties of multifunctional materials

Fluoride Alteration of [3H]Glucose Uptake in Wistar Rat Brain and Peripheral Tissues.

Science.gov (United States)

Rogalska, Anna; Kuter, Katarzyna; Żelazko, Aleksandra; Głogowska-Gruszka, Anna; Świętochowska, Elżbieta; Nowak, Przemysław

2017-04-01

The present study was designed to investigate the role of postnatal fluoride intake on [3H]glucose uptake and transport in rat brain and peripheral tissues. Sodium fluoride (NaF) in a concentration of 10 or 50 ppm was added to the drinking water of adult Wistar rats. The control group received distilled water. After 4 weeks, respective plasma fluoride levels were 0.0541 ± 0.0135 μg/ml (control), 0.0596 ± 0.0202 μg/ml (10 ppm), and 0.0823 ± 0.0199 μg/ml (50 ppm). Although plasma glucose levels were not altered in any group, the plasma insulin level in the fluoride (50 ppm) group was elevated (0.72 ± 0.13 μg/ml) versus the control group (0.48 ± 0.24 μg/ml) and fluoride (10 ppm) group. In rats receiving fluoride for 4 weeks at 10 ppm in drinking water, [3H]glucose uptake was unaltered in all tested parts of the brain. However, in rats receiving fluoride at 50 ppm, [3H]glucose uptake in cerebral cortex, hippocampus, and thalamus with hypothalamus was elevated, versus the saline group. Fluoride intake had a negligible effect on [3H]glucose uptake by peripheral tissues (liver, pancreas, stomach, small intestine, atrium, aorta, kidney, visceral tissue, lung, skin, oral mucosa, tongue, salivary gland, incisor, molars, and jawbone). In neither fluoride group was glucose transporter proteins 1 (GLUT 1) or 3 (GLUT 3) altered in frontal cortex and striatum versus control. On the assumption that increased glucose uptake (by neural tissue) reasonably reflects neuronal activity, it appears that fluoride damage to the brain results in a compensatory increase in glucose uptake and utilization without changes in GLUT 1 and GLUT 3 expression.

A comprehensive phononics of phonon assisted energy transfer in the Yb3+ aided upconversion luminescence of Tm3+ and Ho3+ in solids

International Nuclear Information System (INIS)

Debnath, Radhaballabh; Bose, Saptasree

2015-01-01

The theory of phonon assisted energy transfer is being widely used to explain the Yb 3+ ion aided normal and upconversion emission of various rare earth ions in different Yb 3+ co-doped solids. The reported phonon dynamics in many of these studies are either incomplete or erroneous. Here we report Yb 3+ aided upconversion luminescence properties of Tm 3+ and Ho 3+ in (Yb 3+ /Tm 3+ ) and (Yb 3+ /Ho 3+ ) co-doped two BaO–tellurite glasses and explain their phononics in the light of Dexter's theory by proposing a comprehensive scheme. The approach is valid for other systems of different phonon structures. - Highlights: • Yb 3+ aided upconversion luminescence properties of Tm 3+ and Ho 3+ in (Yb 3+ /Tm 3+ ) and (Yb 3+ /Ho 3+ ) co-doped two BaO–tellurite glasses, are reported. • Phonon assisted energy transfer in these systems are explained in the light of Dexter's theory by proposing a comprehensive scheme of phononics. • The approach is valid for other systems of different phonon structures

Diffusion of fluoride in bovine enamel

International Nuclear Information System (INIS)

Flim, G.J.; Arends, J.; Kolar, Z.

1976-01-01

The uptake of 18 F and the penetration of both F and 18 F in bovine enamel was investigated. Sodium fluoride solutions buffered at pH 7 were employed. The uptake of 18 F was measured by a method described by R. Duckworth and M. Braden, Archs. Oral. Biol., 12(1967), pp. 217-230. The penetration concentration profiles of fluoride (F, 18 F) in the enamel were measured by a sectioning technique. The 18 F uptake in enamel was proportional to approximately tsup(3/4); t being the uptake time. The 18 F concentration as a function of the position in the enamel can be described by: c*(x,t) = c 0 *(t)exp[-α*(t)x]. After correction for the initial fluoride concentration in enamel, for unlabelled fluoride the same dependency is obtained. A model based on simultaneous diffusion and chemical reaction in the pores and diffusion into the hydroxyapatite crystallites will be presented. The results show that diffusion coefficients of the pores are approximately equal to 10 -10 cm 2 s -1 and in the apatite crystallites approximately equal to 10 -17 cm 2 s -1 . The limitations and the approximations of the model are discussed

em cristais de Ho:YLF e Er:YLF na região de 3m

Directory of Open Access Journals (Sweden)

Fábio Henrique Jagosich

2006-01-01

Full Text Available In this work, the deactivation energy transfer mechanisms of 4I13/2 of Er3+ and 5I7 of Ho3+ levels in crystals of LiYF4 (YLF co-doped with Nd3+, Tb3+ and Eu3+ are studied. It was determined the best combination with deactivator ions, capable to maximize the laser gain in the middle of the Ho3+ in 2.9 micrometers (mm and the Er3+ in 2.75 mm operation. The results showed that the Tb3+ and Eu3+ are the best deactivators to the Ho3+ laser operation, while for the Ho3+ laser operation, the best ion deactivator is the Nd3+. The energy transfer characterizations were carried out using the Förster-Dexter method, which consists in the determination of the interaction critic ray, to start from the integral superposition of the absorption cross section spectrum and the involved ions emission.

{sup 166} Ho-EDTMP in detecting bone metastases: preliminary results

Energy Technology Data Exchange (ETDEWEB)

Achando, S.S.; Fernandes, L.; Herrerias, R.; Muramoto, E.; Almeida, M.A.T.; Pereira, N.S. de; Mengatti, J. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

1995-12-31

Holmium-166-EDTMP (ethylene-dimine-tetra methylene phosphonic acid) due to its promising biological properties, has proved to be a palliating therapeutic agent for bone cancer in human beings. In a basic medium, {sup 166} Ho-EDTMP can be readily prepared with a complexing molar ratio EDTMP/Ho 4.34. The radiochemical purity of the complex was higher than 98%. The biodistribution in rats and mice, showed a high skeletal uptake, a fast blood clearance and a low soft tissue uptake and a lesion to normal bone ratio equal to 2. (author). 3 refs., 4 tabs.

Microstructural and dielectrical characterization of Ho doped BaTiO3 ceramics

Directory of Open Access Journals (Sweden)

Marjanović Miloš

2014-01-01

Full Text Available The Ho doped BaTiO3 ceramics, with different Ho2O3 content, ranging from 0.01 to 1.0 wt % Ho, were investigated regarding their microstructural and dielectric characteristics. Doped BaTiO3 were prepared using conventional solid state reaction and sintered at 1380°C for four hours. SEM analysis of Ho/BaTiO3 doped ceramics showed that the low doped samples exhibit mainly fairly uniform and homogeneous microstructure with the grain size ranged from 20-40 μm. In the samples with the higher dopant concentration the abnormal grain growth is inhibited and the grain size ranged between 2-10 μm. Measurements of dielectric properties were carried out as a function of temperature up to 180 °C at different frequencies. The samples doped with 0.01wt % of Ho, exhibit the high value of dielectric permittivity (εr = 2160 at room temperature. A nearly flat permittivity-response was obtained in specimens with higher additive content. Using a Curie-Weiss law and modified Curie-Weiss law the Curie constant (C, Curie temperature (Tc and a critical exponent of nonlinearity (g were calculated. The Curie temperature of doped samples were ranged from 128 to 130°C. The Curie constant for all series of samples decrease with increase of dopant concentration and the lowest values were observed on samples doped with 0.01 wt % of holmium. [Projekat Ministarstva nauke Republike Srbije, br. OI 172057: Directed synthesis, structure and properties of multifunctional materials i br. TR 32026

Energy transfer characteristics of silicate glass doped with Er{sup 3+}, Tm{sup 3+}, and Ho{sup 3+} for ∼2 μm emission

Energy Technology Data Exchange (ETDEWEB)

Li, Ming; Liu, Xueqiang [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Guo, Yanyan [College of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Hu, Lili [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhang, Junjie [College of Materials Science and Engineering, China Jiliang University, Hangzhou 310 018 (China)

2013-12-28

A Er{sup 3+}/Tm{sup 3+}/Ho{sup 3+} tri-doped silicate glass with good thermal stability is prepared by melt-quenching method. Efficient ∼2 μm emission is observed under 808 nm laser excitation. It is found that the 2.0 μm emission of Ho{sup 3+} can be enhanced under the excitation at 808 nm by incorporating Er{sup 3+} and Tm{sup 3+}. Based on the measurement of absorption spectra, the Judd–Ofelt intensity parameters, radiation emission probability, and branching ratio are calculated to evaluate the spectroscopic properties simultaneously. The maximum value of emission cross section of Ho{sup 3+} is 3.54 × 10{sup −21} cm{sup 2} at 2008 nm. Additionally, the phonon assistance and the micro-parameters in the energy transfer process are quantitatively analyzed by using Dexter model. The energy transfer coefficient from Tm{sup 3+} to Ho{sup 3+} can reach as high as 21.44 × 10{sup −40} cm{sup 6}/s, respectively. The emission property together with good thermal property indicates that Er{sup 3+}/Tm{sup 3+}/Ho{sup 3+} tri-doped silicate glass is a potential kind of laser glass for efficient 2 μm laser.

Preparation, characterization and luminescence of nanocrystalline Y2O3:Ho

International Nuclear Information System (INIS)

Biljan, Tomislav; Gajovic, Andreja; Meic, Zlatko; Mestrovic, Ernest

2007-01-01

Nanocrystalline Y 2 O 3 :Ho was synthesized by solution combustion method with ethylene glycol as fuel. Material was characterized using powder X-ray diffraction and transmission electron microscopy (TEM). X-ray diffraction and TEM showed that the material is nanostructured. Luminescence properties were studied using Raman spectrometers with excitation in near infrared (NIR) and visible regions. The visible and NIR luminescence spectra of nanocrystalline Y 2 O 3 :Ho show some important differences from those of bulk material. The convenience of using Raman instruments for studying luminescence of lanthanide ions is demonstrated

Omega-3 polyunsaturated fatty acid has an anti-oxidant effect via the Nrf-2/HO-1 pathway in 3T3-L1 adipocytes

International Nuclear Information System (INIS)

Kusunoki, Chisato; Yang, Liu; Yoshizaki, Takeshi; Nakagawa, Fumiyuki; Ishikado, Atsushi; Kondo, Motoyuki; Morino, Katsutaro; Sekine, Osamu; Ugi, Satoshi; Nishio, Yoshihiko; Kashiwagi, Atsunori; Maegawa, Hiroshi

2013-01-01

Highlights: ► Omega-3 PUFA has a direct anti-oxidant effect in adipocytes. ► EPA and DHA induce HO-1 expression in 3T3-L1 adipocytes. ► Omega-3 PUFA and its end-product, 4-HHE, activates the Nrf-2/HO-1 pathway. ► Omega-3 PUFA protects against oxidative stress-induced cytotoxicity. -- Abstract: Oxidative stress is produced in adipose tissue of obese subjects and has been associated with obesity-related disorders. Recent studies have shown that omega-3 polyunsaturated fatty acid (ω3-PUFA) has beneficial effects in preventing atherosclerotic diseases and insulin resistance in adipose tissue. However, the role of ω3-PUFA on adipocytes has not been elucidated. In this study, 3T3-L1 adipocytes were treated with ω3-PUFA and its metabolites, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or 4-hydroxy hexenal (4-HHE). ω3-PUFA and its metabolites dose-dependently increased mRNA and protein levels of the anti-oxidative enzyme, heme oxygenase-1 (HO-1); whereas no changes in the well-known anti-oxidant molecules, superoxide dismutase, catalase, and glutathione peroxidase, were observed. Knockdown of nuclear factor erythroid 2-related factor 2 (Nrf-2) significantly reduced EPA, DHA or 4-HHE-induced HO-1 mRNA and protein expression. Also, pretreatment with ω3-PUFA prevented H 2 O 2 -induced cytotoxicity in a HO-1 dependent manner. In conclusion, treatment with EPA and DHA induced HO-1 through the activation of Nrf-2 and prevented oxidative stress in 3T3-L1 adipocytes. This anti-oxidant defense may be of high therapeutic value for clinical conditions associated with systemic oxidative stress.

Electronic absorption bands of HoCl3 and SmCl3 complexes in alcohols

International Nuclear Information System (INIS)

Ramesh Babu, V.; Buddhudu, S.; Rangarajan, V.N.

1987-01-01

The normal absorption and second derivative spectra of ten alcoholic complexes of HoCl 3 and SmCl 3 were recorded. From the observed bands, energies and intensity values were measured. To fit in these measured values with the theoretical values, a set of spectroscopic parameters namely, Judd-Ofelt (T 2 , T 4 , T 6 ), intensity (Ω 2 , Ω 4 , Ω 6 ) had been computed. A good fit of intensities was obtained between the experimental and theoretical data. The environmental influences on the intensities of the hypersensitive transitions of Sm(III) and Ho(III) ions were found to be noteworthy. (author). 7 tables, 20 refs

Urinary fluoride excretion after application of fluoride varnish and use of fluoride toothpaste in young children

DEFF Research Database (Denmark)

Lockner, Frida; Twetman, Svante; Stecksén-Blicks, Christina

2017-01-01

BACKGROUND: The efficacy and safety of combined use of topical fluoride products are essential issues that must be monitored. AIM: To assess urinary excretion of fluoride after application of two different dental varnishes containing 2.26% fluoride in 3- to 4-year-old children and to compare...... the levels with and without parallel use of fluoride toothpaste. DESIGN: Fifteen healthy children were enrolled to a randomized crossover trial that was performed in two parts: Part I with twice-daily tooth brushing with fluoride toothpaste and Part II with twice-daily brushing with a non-fluoride toothpaste....... After a 1-week run-in period, 0.1 mL of the two fluoride varnishes (Duraphat and Profluorid Varnish) was topically applied in a randomized order. Baseline and experimental urine was collected during 6-h periods. The fluoride content was determined with an ion-sensitive electrode. RESULTS...

Magnetic properties of pure and Fe doped HoCrO{sub 3} thin films fabricated via a solution route

Energy Technology Data Exchange (ETDEWEB)

Yin, Shiqi; Sauyet, Theodore [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Guild, Curt [Department of Chemistry, University of Connecticut, Storrs, CT 06269 (United States); Suib, S.L. [Department of Chemistry, University of Connecticut, Storrs, CT 06269 (United States); Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Jain, Menka, E-mail: menka.jain@uconn.edu [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States)

2017-04-15

Multiferroic properties of orthorhombically distorted perovskite rare-earth chromites, such as HoCrO{sub 3}, are being investigated extensively in recent years. In the present work, we report on the effect of Fe substitution on the magnetic properties of HoCrO{sub 3} thin films. Thin films of HoCrO{sub 3} and HoCr{sub 0.7}Fe{sub 0.3}O{sub 3} were fabricated via a solution route on platinized silicon substrates. Structural properties of the films were evaluated by X-ray diffraction and Raman spectroscopy techniques. The surface morphology and cross-sections of the films were examined using scanning electron microscopy. Optical band gaps of pure and Fe doped HoCrO{sub 3} films are found to be 3.45 eV and 3.39 eV, respectively. The magnetization measurements show that the Néel temperatures (where Cr{sup 3+} orders) for the HoCrO{sub 3} and HoCr{sub 0.7}Fe{sub 0.3}O{sub 3} films are 134 and 148 K, respectively. In a magnetic field of 2 T, the maximum entropy change and relative cooling power, two parameters to evaluate the magnetocaloric properties of a material, were 0.813 J/kg K at 11 K and 21.1 J/kg for HoCrO{sub 3} film, in comparison with 0.748 J/kg K at 15 K and 26.8 J/kg for HoCr{sub 0.7}Fe{sub 0.3}O{sub 3} film. To our knowledge, this is the first work exploring the band gap and magnetocaloric properties of rare-earth chromite thin films. These findings should inspire the development of rare-earth chromite thin films for temperature control of nanoscale electronic devices and sensors in the low temperature region (< 30 K). - Highlights: • Phase-pure HoCrO{sub 3} and HoCr{sub 0.7}Fe{sub 0.3}O{sub 3}films were fabricated on platinized Sivia a solution route. • This is the first work on the exploration of band gap and magnetocaloric properties of rare-earth chromitefilms. • From 0-2 T, maximum entropy change for the HoCrO{sub 3} film was 0.813 J/kg K at 11 K.From 0-2 T, maximum entropy change for HoCr{sub 0.7}Fe{sub 0.3}O{sub 3} film was 0.748 J/kg K at 15

Controllable upconversion luminescence and temperature sensing behavior in NaGdF4:Yb3+/Ho3+/Ce3+ nano-phosphors

Science.gov (United States)

Pang, Tao; Wang, Jiajun

2018-01-01

The hexagonal NaGdF4:Yb3+/Ho3+/Ce3+ nano-phosphors are synthesized by a hydrothermal method. Under 980 nm excitation, the phosphor emits green, red and far-red light in the visible wavelength region, corresponding to the 5S2/5F4 → 5I8, 5F5 → 5I8 and 5S2/5F4 → 5I7 transitions of Ho3+ ions, respectively. When adjusting the Ce3+ concentration from 0% to 16%, the dominant wavelength shifts ˜43 nm toward the longer wavelength. Two cross-relaxation processes between Ho3+ and Ce3+ are responsible for the change in chromaticity. Also, the ability of the Ce3+ concentration to regulate the luminescence color depends on the pumping power and temperature of samples. More interestingly, the phosphors are potentially applicable as the optical thermometric materials. In the case of 16% Ce3+ doping, the maximum sensitivity (0.1446 K-1) about 4-35 times as high as the reported values of several typical thermometric materials is obtained.

Energy transfer and 2.0 μm emission in Tm{sup 3+}/Ho{sup 3+} co-doped α-NaYF{sub 4} single crystals

Energy Technology Data Exchange (ETDEWEB)

Feng, Zhigang; Yang, Shuo [Key laboratory of Photo-electronic Materials, Ningbo University, Ningbo, Zhejiang 315211 (China); Xia, Haiping, E-mail: hpxcm@nbu.edu.cn [Key laboratory of Photo-electronic Materials, Ningbo University, Ningbo, Zhejiang 315211 (China); Wang, Cheng; Jiang, Dongsheng; Zhang, Jian; Gu, Xuemei; Zhang, Yuepin [Key laboratory of Photo-electronic Materials, Ningbo University, Ningbo, Zhejiang 315211 (China); Chen, Baojiu, E-mail: bjchen@dlmu.edu.cn [Department of Physics, Dalian Maritime University, Dalian, Liaoning Province 116026 (China); Jiang, Haochuan [Ningbo Institute of Materials Technology and Engineering, the Chinese Academy of Sciences, Ningbo, Zhejiang 315211 (China)

2016-04-15

Highlights: • Cubic NaYF{sub 4} single crystals co-doped with ∼1.90 mol% Tm{sup 3+} and various Ho{sup 3+} concentrations were grown by Bridgman method. • The maximum fluorescence lifetime was 23.23 ms for Tm{sup 3+} (1.90 mol%)/Ho{sup 3+} (3.89 mol%) co-doped α-NaYF{sub 4}. • The obtained energy transfer rate (W{sub ET}) and energy transfer efficiency (η) of Tm{sup 3+}:{sup 3}F{sub 4} are 1077 s{sup −1} and 95.0%, respectively. • The maximum emission cross section reached 1.06 × 10{sup −20} cm{sup 2}. - Abstract: Cubic NaYF{sub 4} single crystals co-doped with ∼1.90 mol% Tm{sup 3+} and various Ho{sup 3+} concentrations were grown by Bridgman method. The energy transfer from Tm{sup 3+} to Ho{sup 3+} and the optimum fluorescence emission around 2.04 μm of Ho{sup 3+} ion were investigated based on the measured absorption spectra, emission spectra, emission cross section and decay curves under excitation of 800 nm LD. The emission intensity at 2.04 μm increased with the increase of Ho{sup 3+} concentration from 0.96 mol% to 3.89 mol% when the concentration of Tm{sup 3+} was held constantly at ∼1.90 mol%. Moreover, the maximum emission cross section reached 1.06 × 10{sup −20} cm{sup 2} and the maximum fluorescence lifetime was 23.23 ms for Tm{sup 3+}(1.90 mol%)/Ho{sup 3+}(3.89 mol%) co-doped one. According to the measured lifetime of Tm{sup 3+} single-doped and Tm{sup 3+}/Ho{sup 3+} co-doped samples, the maximum energy transfer efficiency of Tm{sup 3+}:{sup 3}F{sub 4} level was 95.0%. Analysis on the fluorescence dynamics indicated that electric dipole–dipole is dominant for the energy transfer from Tm{sup 3+} to Ho{sup 3+}.

Omega-3 polyunsaturated fatty acid has an anti-oxidant effect via the Nrf-2/HO-1 pathway in 3T3-L1 adipocytes

Energy Technology Data Exchange (ETDEWEB)

Kusunoki, Chisato, E-mail: yosizaki@belle.shiga-med.ac.jp [Department of Medicine, Shiga University of Medical Science, Seta Tsukinowa-Cho, Otsu, Shiga 520-2192 (Japan); Yang, Liu; Yoshizaki, Takeshi; Nakagawa, Fumiyuki; Ishikado, Atsushi; Kondo, Motoyuki; Morino, Katsutaro; Sekine, Osamu; Ugi, Satoshi [Department of Medicine, Shiga University of Medical Science, Seta Tsukinowa-Cho, Otsu, Shiga 520-2192 (Japan); Nishio, Yoshihiko [Division of Diabetes, Metabolism and Endocrinology, Department of Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544 (Japan); Kashiwagi, Atsunori; Maegawa, Hiroshi [Department of Medicine, Shiga University of Medical Science, Seta Tsukinowa-Cho, Otsu, Shiga 520-2192 (Japan)

2013-01-04

Highlights: Black-Right-Pointing-Pointer Omega-3 PUFA has a direct anti-oxidant effect in adipocytes. Black-Right-Pointing-Pointer EPA and DHA induce HO-1 expression in 3T3-L1 adipocytes. Black-Right-Pointing-Pointer Omega-3 PUFA and its end-product, 4-HHE, activates the Nrf-2/HO-1 pathway. Black-Right-Pointing-Pointer Omega-3 PUFA protects against oxidative stress-induced cytotoxicity. -- Abstract: Oxidative stress is produced in adipose tissue of obese subjects and has been associated with obesity-related disorders. Recent studies have shown that omega-3 polyunsaturated fatty acid ({omega}3-PUFA) has beneficial effects in preventing atherosclerotic diseases and insulin resistance in adipose tissue. However, the role of {omega}3-PUFA on adipocytes has not been elucidated. In this study, 3T3-L1 adipocytes were treated with {omega}3-PUFA and its metabolites, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or 4-hydroxy hexenal (4-HHE). {omega}3-PUFA and its metabolites dose-dependently increased mRNA and protein levels of the anti-oxidative enzyme, heme oxygenase-1 (HO-1); whereas no changes in the well-known anti-oxidant molecules, superoxide dismutase, catalase, and glutathione peroxidase, were observed. Knockdown of nuclear factor erythroid 2-related factor 2 (Nrf-2) significantly reduced EPA, DHA or 4-HHE-induced HO-1 mRNA and protein expression. Also, pretreatment with {omega}3-PUFA prevented H{sub 2}O{sub 2}-induced cytotoxicity in a HO-1 dependent manner. In conclusion, treatment with EPA and DHA induced HO-1 through the activation of Nrf-2 and prevented oxidative stress in 3T3-L1 adipocytes. This anti-oxidant defense may be of high therapeutic value for clinical conditions associated with systemic oxidative stress.

γ-Aminobutyric acid ameliorates fluoride-induced hypothyroidism in male Kunming mice.

Science.gov (United States)

Yang, Haoyue; Xing, Ronge; Liu, Song; Yu, Huahua; Li, Pengcheng

2016-02-01

This study evaluated the protective effects of γ-aminobutyric acid (GABA), a non-protein amino acid and anti-oxidant, against fluoride-induced hypothyroidism in mice. Light microscope sample preparation technique and TEM sample preparation technique were used to assay thyroid microstructure and ultrastructure; enzyme immunoassay method was used to assay hormone and protein levels; immunohistochemical staining method was used to assay apoptosis of thyroid follicular epithelium cells. Subacute injection of sodium fluoride (NaF) decreased blood T4, T3 and thyroid hormone-binding globulin (TBG) levels to 33.98 μg/l, 3 2.8 ng/ml and 11.67 ng/ml, respectively. In addition, fluoride intoxication induced structural abnormalities in thyroid follicles. Our results showed that treatment of fluoride-exposed mice with GABA appreciably decreased metabolic toxicity induced by fluoride and restored the microstructural and ultrastructural organisation of the thyroid gland towards normalcy. Compared with the negative control group, GABA treatment groups showed significantly upregulated T4, T3 and TBG levels (42.34 μg/l, 6.54 ng/ml and 18.78 ng/ml, respectively; Plevel and apoptosis inhibition in thyroid follicular epithelial cells. To the best of our knowledge, this is the first study to establish the therapeutic efficacy of GABA as a natural antioxidant in inducing thyroprotection against fluoride-induced toxicity. Copyright © 2015 Elsevier Inc. All rights reserved.

Magnetic ordering of Hf{sub 3}Ni{sub 2}Si{sub 3}-type {Sm, Tb, Er}{sub 3}Co{sub 2}Ge{sub 3} and {Tb, Ho}{sub 3}Ni{sub 2}Ge{sub 3} compounds

Energy Technology Data Exchange (ETDEWEB)

Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, Moscow, GSP-1, 119991 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India); Quezado, S.; Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil); Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Isnard, O. [CNRS, Institut. Néel, 25 rue des Martyrs BP166 x, F-38042 Grenoble (France); Université Grenoble Alpes, Inst. Néel, F-38042 Grenoble (France)

2017-02-15

The magnetic ordering of Hf{sub 3}Ni{sub 2}Si{sub 3}-type {Sm, Tb, Er}{sub 3}Co{sub 2}Ge{sub 3} and {Tb, Ho}{sub 3}Ni{sub 2}Ge{sub 3} compounds (space group Cmcm, oC32) was investigated via magnetization measurements and neutron diffraction study in a zero-applied field. {Sm, Tb, Er}{sub 3}Co{sub 2}Ge{sub 3} and Ho{sub 3}Ni{sub 2}Ge{sub 3} exhibit field sensitive complex antiferromagnetic orderings with T{sub N}=51 K, T{sub m}=10 K for Sm{sub 3}Co{sub 2}Ge{sub 3}, T{sub N}=34 K, T{sub m}=13 K for Tb{sub 3}Co{sub 2}Ge{sub 3}, T{sub N}=7 K for Er{sub 3}Co{sub 2}Ge{sub 3} and T{sub N}=11 K for Ho{sub 3}Ni{sub 2}Ge{sub 3}. At 2 K and above the critical field of ~5 kOe, 20 kOe, 4 kOe and 7 kOe for Sm{sub 3}Co{sub 2}Ge{sub 3}, Tb{sub 3}Co{sub 2}Ge{sub 3}, Er{sub 3}Co{sub 2}Ge{sub 3} and Ho{sub 3}Ni{sub 2}Ge{sub 3}, respectively, saturation magnetizations per rare-earth atom are 6.5 μ{sub B} for Tb{sub 3}Co{sub 2}Ge{sub 3}, 7.0 μ{sub B} for Er{sub 3}Co{sub 2}Ge{sub 3} and 8.0 μ{sub B} for Ho{sub 3}Ni{sub 2}Ge{sub 3} in the field of 140 kOe, whereas magnetization of Sm{sub 3}Co{sub 2}Ge{sub 3} has an antiferromagnetic behaviour. The isothermal magnetic entropy change, ΔS{sub m}, indicates a field-induced ferromagnetic ordering in Sm{sub 3}Co{sub 2}Ge{sub 3}, Tb{sub 3}Co{sub 2}Ge3, Er{sub 3}Co{sub 2}Ge{sub 3} and Ho{sub 3}Ni{sub 2}Ge{sub 3} with a maximal ΔS{sub m} value of −10.9 J/kg K for Ho{sub 3}Ni{sub 2}Ge{sub 3} at 11 K for a field change of 50 kOe. In a zero-applied magnetic field, below T{sub N}=33 K and down to T{sub m}{sup ND}=15 K Tb{sub 3}Ni{sub 2}Ge{sub 3} shows an ac-antiferromagnetic ordering with the C2′/c magnetic space group, a K{sub 0}=[0, 0, 0] propagation vector and a a{sub Tb3Ni2Ge3}×b{sub Tb3Ni2Ge3}×c{sub Tb3Ni2Ge3} magnetic unit cell. Below T{sub m}{sup ND}=15 K, its magnetic structure is a sum of the ac-antiferromagnetic component with the C2′/c magnetic space group of the K{sub 0} vector and a sine-modulated a

Zwei Briefe auf Guaraní in Alexander von Humboldts Handschrift

Directory of Open Access Journals (Sweden)

Manfred Ringmacher

2014-12-01

Full Text Available Gegenstand des Aufsatzes von Manfred Ringmacher sind zwei Briefe auf Guaraní in Alexander von Humboldts Handschrift. Die Originale der Abschriften wurden im Jahr 1800 in der ehemals jesuitisch betreuten Indianersiedlung Santa María la Mayor am Río Uruguay geschrieben und an den Vizekönig des spanischen Vizekönigreichs La Plata gesandt. Sie sind mit einer zeitgenössischen spanischen Übersetzung versehen; außerdem hat Alexander von Humboldt in französischer Sprache noch einige Erläuterungen gegeben.

Synthesis and characterization of Ho{sup 3+}-doped strontium titanate downconversion nanocrystals and its application in dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Li, Y.Y. [Department of Inorganic Nonmetallic Materials Engineering, Dalian Polytechnic University, Dalian 116034 (China); Liaoning Provincial College Key Laboratory of New Materials and Material Modification, Dalian Polytechnic University, Dalian 116034 (China); Hao, H.S., E-mail: beike1952@163.com [Department of Inorganic Nonmetallic Materials Engineering, Dalian Polytechnic University, Dalian 116034 (China); Liaoning Provincial College Key Laboratory of New Materials and Material Modification, Dalian Polytechnic University, Dalian 116034 (China); Qin, L. [National Engineering Research Center of Seafood, Dalian Polytechnic University, Dalian 116034 (China); Wang, H.L.; Nie, M.Q.; Hu, Z.Q.; Gao, W.Y.; Liu, G.S. [Department of Inorganic Nonmetallic Materials Engineering, Dalian Polytechnic University, Dalian 116034 (China); Liaoning Provincial College Key Laboratory of New Materials and Material Modification, Dalian Polytechnic University, Dalian 116034 (China)

2015-02-15

Highlights: • A new downconversion (DC) nanocrystal (SrTiO{sub 3}:Ho{sup 3+}) was synthesized. • The effect of SrTiO{sub 3}:Ho{sup 3+} as a photoanode in DSSCs was investigated. • SrTiO{sub 3}:Ho{sup 3+} absorb ultraviolet light and downconvert it to visible light. • DC SrTiO{sub 3}:Ho{sup 3+} as a photoanode achieve the higher photoelectric conversion efficiency. - Abstract: Ho{sup 3+}-doped strontium titanate (SrTiO{sub 3}:Ho{sup 3+}) downconversion (DC) nanocrystals are synthesized by the solid state interaction of titanium dioxide, strontium nitrate, holmium oxide and sodium chloride and then used as a photoanode in dye-sensitized solar cells (DSSCs) to investigate the effect of DC nanocrystals in DSSCs. Differential thermal analysis, X-ray diffraction, scanning electronic microscope, energy dispersive spectroscopy and Brunauer-Emmet-Teller analysis confirmed the formation of cubic structured SrTiO{sub 3}:Ho{sup 3+} nanocrystals with diameters of 40-400 nm, pore size of ∼45 nm, sintering temperature of 950 °C. The photofluorescence and UV-Vis absorption spectra of the SrTiO{sub 3}:Ho{sup 3+} nanocrystals revealed strong emission intensity and visible light absorption when doped content of holmium oxide was between 1 wt% and 3 wt%. Compared with the pure SrTiO{sub 3} photoanode, SrTiO{sub 3}:Ho{sup 3+} DC photoanode showed a greater photovoltaic efficiency. The photoelectric conversion efficiency (η) of the DSSCs with a SrTiO{sub 3}:Ho{sup 3+} photoanode doped with 1 wt% holmium oxide was 59% higher than that with a pure SrTiO{sub 3} photoanode. This phenomenon could be explained by SrTiO{sub 3}:Ho{sup 3+} nanocrystals’ ability to absorb ultraviolet light and downconvert it to visible light, which extends spectral response range of DSSC to the ultraviolet region and increased the short-circuit current density (Jsc) of DSSCs.

Controlled synthesis, formation mechanism, and carbon oxidation properties of Ho{sub 2}Cu{sub 2}O{sub 5} nanoplates prepared with a coordination-complex method

Energy Technology Data Exchange (ETDEWEB)

Guo, Rui [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); School of Metallurgy, Northeastern University, Shenyang 110004 (China); You, Junhua [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870 (China); Han, Fei; Li, Chaoyang; Zheng, Guiyuan; Xiao, Weicheng [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); Liu, Xuanwen, E-mail: lxw@mail.neuq.edu.cn [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); School of Metallurgy, Northeastern University, Shenyang 110004 (China)

2017-02-28

Highlights: • The crystallization mechanism relies on Ho{sup 3+} and Cu{sup 2+} diffusion. • The Ho{sub 2}Cu{sub 2}O{sub 5} particles are refined by the coordination complex method under N{sub 2} environment. • The catalytic oxidation activity of Ho{sub 2}Cu{sub 2}O{sub 5} samples for carbon is enhanced. - Abstract: Ho{sub 2}Cu{sub 2}O{sub 5} nanoplates with perovskite structures were synthesized via a simple solution method (SSM) and a coordination-complex method (CCM) using [HoCu(3,4-pdc){sub 2}(OAc)(H{sub 2}O){sub 3}]·8H{sub 2}O (L = 3,4-pyridinedicarboxylic acid) as a precursor. The CCM was also performed in an N{sub 2} environment (CCMN) under various calcination conditions. The crystallization processes were characterized using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. Ho{sub 2}Cu{sub 2}O{sub 5} formed through the diffusion of CuO into Ho{sub 2}O{sub 3} particles. Cu{sup 2+} diffused faster than Ho{sup 3+} during this process. The initial products of CCMN (along with the thermal decomposition products) were initially laminarized in the N{sub 2} atmosphere, which prevented the growth of CuO particles and decreased the size of the Ho{sub 2}Cu{sub 2}O{sub 5} particles. The final Ho{sub 2}Cu{sub 2}O{sub 5} particles from CCMN had a nanoplate morphology with an average thickness of 75 nm. The decomposition of organic molecules and protection from N{sub 2} played important roles in determining the morphology of the resulting Ho{sub 2}Cu{sub 2}O{sub 5}. The catalytic oxidation activity of Ho{sub 2}Cu{sub 2}O{sub 5} samples for carbon was characterized using a specific surface area measurement and thermogravimetric analysis, which revealed that the samples produced by CCMN had the highest catalytic activity.

Comparison of concentrations of drugs between blood samples with and without fluoride additive-important findings for Δ9-tetrahydrocannabinol and amphetamine.

Science.gov (United States)

Wiedfeld, Christopher; Krueger, Julia; Skopp, Gisela; Musshoff, Frank

2018-02-17

Fluoride is a common stabilizing agent in forensic toxicology to avoid the frequent problem of degradation of drugs in blood samples especially described for cocaine. In cases only samples with addition of fluoride are available, it is a crucial question if also concentrations of common drugs other than cocaine (amphetamines, opiates and cannabinoids) are affected by fluoride. So far, there are only rare literature data available on discrepant results especially for Δ 9 -tetrahydrocannabinol (THC). In this study, comparative analysis of positive tested paired routine plasma/serum samples (n = 375), collected at the same time point (one device with and one without fluoride), was carried out with special focus on cannabinoids. Samples were measured with validated routine liquid chromatography-tandem mass spectrometry methods for THC, 11-hydroxy-THC (THC-OH), 11-nor-9-carboxy-THC (THC-COOH), cocaine, benzoylecgonine, ecgonine methyl ester, morphine, codeine, amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, and 3,4-methylenedioxyethylamphetamine, and results were statistically evaluated. Beside the expected stabilization effect on cocaine and the consequently reduced concentration of ecgonine methyl ester in fluoride samples, benzoylecgonine was elevated compared to respective samples without fluoride. Most importantly, new findings were significantly reduced mean concentrations of THC (- 17%), THC-OH (- 17%), and THC-COOH (- 22%) in fluoride samples. Mean amphetamine concentration was significantly higher in samples with the additive (+ 6%). For the other amphetamine type of drugs as well as for morphine and codeine, no significant differences could be seen. Whenever specified thresholds have been set, such as in most European countries, the use of different blood sample systems may result in a motorist being differently charged or prosecuted. The findings will support forensic toxicologists at the

Fluoride concentration in urine after silver diamine fluoride application on tooth enamel

Science.gov (United States)

Sari, D. L.; Bahar, A.; Gunawan, H. A.; Adiatman, M.; Rahardjo, A.; Maharani, D. A.; Toptanci, I. R.; Yavuz, I.

2017-08-01

Silver Diammine Fluoride (SDF), which contains fluoride, is known to inhibit tooth enamel demineralization and increase fluoride concentrations in saliva and urine. The aim of this study is to analyze the fluoride concentration in urine after application of SDF on tooth enamel. Urine from four subjects was collected prior to, 30 minutes after, and two and three hours after the application of SDF, and an ion-selective electrode was used to measure the fluoride concentrations. There was no significant difference between time 1 and time 2, time 1 and time 3, time 1 and time 4, time 2 and 3 (p > 0.05), and there was a significant difference between time 2 and time 4 as well as time 3 and time 4 (p < 0.05). There was a decrease in the concentration of fluoride ions in urine from the baseline to 30 minutes after application, and an increase from baseline to two and three hours after the application of SDF.

Magnetic and magnetocaloric properties of HoCr0.75Fe0.25O3 compound

Science.gov (United States)

Kotnana, Ganesh; Babu, P. D.; Jammalamadaka, S. Narayana

2018-05-01

We report on the magnetic and magnetocaloric properties of HoCr0.75Fe0.25O3 compound around the Néel temperature (TN), which is due to Cr3+ ordering. Susceptibility (χ) vs. temperature (T) graph of HoCr0.75Fe0.25O3 compound infer two transitions due to the ordering of Cr3+ moments (TN ˜ 155 K) and Ho3+ moments (TNHo ˜ 8 K). Magnetic entropy (-ΔSM) value of 1.14 J kg-1 K-1 around 157.5 K with a magnetic field (H) of 90 kOe is attributed to antiferromagnetic (AFM) ordering of Cr3+ moments. A maximum value of adiabatic temperature (ΔTad) ˜ 0.41 K around TN is obtained and is found to increases with applied magnetic field. Negative slope for H/M vs. M2 graph is evident for HoCr0.75Fe0.25O3 compound below TN, which indicates the first order phase transition. Quantified values of -ΔSM and ΔTad open the way to explore rare earth orthochromites for the MCE properties and refrigeration applications.

Investigation of upconversion luminescence in antimony–germanate double-clad two cores optical fiber co-doped with Yb{sup 3+}/Tm{sup 3+} and Yb{sup 3+}/Ho{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Zmojda, J.; Kochanowicz, M.; Miluski, P.; Dorosz, J. [Bialystok University of Technology, Wiejska 45 Street, 15-351 Bialystok (Poland); Pisarska, J.; Pisarski, W.A. [Institute of Chemistry, University of Silesia, Szkolna 9, 40-007 Katowice (Poland); Dorosz, D., E-mail: d.dorosz@pb.edu.pl [Bialystok University of Technology, Wiejska 45 Street, 15-351 Bialystok (Poland)

2016-02-15

In the paper double-clad optical fiber with two off-set cores co-doped with 1Yb{sub 2}O{sub 3}–0.1Tm{sub 2}O{sub 3} and 1Yb{sub 2}O{sub 3}–0.5Ho{sub 2}O{sub 3} has been investigated. Antimony–germanate glass was melted as a matrix for active cores. The concentration of lanthanides and their ratio have been optimized to achieve maximum upconversion emission intensity at 478 nm ({sup 1}G{sub 4}→{sup 3}H{sub 6}) and 650 nm ({sup 1}G{sub 4}→{sup 3}F{sub 4}) in glasses doped with Tm{sup 3+} ions and 545 nm and 655 nm, corresponding to the {sup 5}F{sub 5}→{sup 5}I{sub 8} and {sup 5}F{sub 4}→{sup 5}I{sub 8} transitions in holmium ions. The energy transfer efficiency in glasses used as optical fiber cores was η{sub Tm}=56% (0.1 mol% Tm{sub 2}O{sub 3}) and η{sub Ho}=85% (0.5 mol% Ho{sub 2}O{sub 3}), respectively. As a result of excitation of the fabricated optical fiber (λ{sub exc}=976 nm), a UC luminescence spectra was obtained. Superposition of three emission bands at the wavelengths of 481 nm (Tm{sup 3+}: blue), 545 nm (Ho{sup 3+}:green) and 665 nm (Tm{sup 3+}, Ho{sup 3+}: red) from two separated cores was measured. Influence of fiber length and excitation power on the color coordinates (CIE-1931) have been also investigated. - Highlights: • Antimony-germanate glasses co-doped with Yb{sup 3+}/Tm{sup 3+} and Yb{sup 3+}/Ho{sup 3+} were presented. • UC luminescence in double-clad, two off-set core co-doped with Yb{sup 3+}/Tm{sup 3+} and Yb{sup 3+}/Ho{sup 3+} optical fiber was presented. • The chromatic coordinates shift in the blue region at CIE scheme as a function of pump power and length of optical fiber was observed.

Molecular Fluoride-Bridged 3d-4f Complexes and Their Magnetic Properties

DEFF Research Database (Denmark)

Pedersen, K. S.; Bendix, J.

2016-01-01

trifluorides with very high lattice enthalpies, building block approaches are not limited to robust systems and use of labile transition metal fluoride complexes has met with unexpected success. The physical properties of fluoride-bridged 3d-4f systems are crucially dependent on coordination geometries, which...... be utilized efficiently in tailored synthesis of polynuclear complexes and extended structures. In particular, the strong affinity of the lanthanides for fluoride makes it a good choice for directed synthesis of mixed lanthanide-transition metal complexes. Despite the competition from formation of lanthanide...

Study of Ho-doped Bi{sub 2}Te{sub 3} topological insulator thin films

Energy Technology Data Exchange (ETDEWEB)

Harrison, S. E. [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Collins-McIntyre, L. J.; Zhang, S. L.; Chen, Y. L.; Hesjedal, T., E-mail: Thorsten.Hesjedal@physics.ox.ac.uk [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Baker, A. A. [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Figueroa, A. I.; Laan, G. van der [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Kellock, A. J.; Pushp, A.; Parkin, S. S. P. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States); Harris, J. S. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

2015-11-02

Breaking time-reversal symmetry through magnetic doping of topological insulators has been identified as a key strategy for unlocking exotic physical states. Here, we report the growth of Bi{sub 2}Te{sub 3} thin films doped with the highest magnetic moment element Ho. Diffraction studies demonstrate high quality films for up to 21% Ho incorporation. Superconducting quantum interference device magnetometry reveals paramagnetism down to 2 K with an effective magnetic moment of ∼5 μ{sub B}/Ho. Angle-resolved photoemission spectroscopy shows that the topological surface state remains intact with Ho doping, consistent with the material's paramagnetic state. The large saturation moment achieved makes these films useful for incorporation into heterostructures, whereby magnetic order can be introduced via interfacial coupling.

Penetration of fluoride-containing self-gelling liquids into human molar occlusal fissures in vitro.

Science.gov (United States)

Bottenberg, P; Slop, D; Coomans, D

1989-01-01

In this in vitro study the ability and speed of self-gelling liquid compositions to penetrate into fissures were evaluated. Two formulations containing either tetraethylsilicate, ammonium fluoride, and sodium lauryl sulfate or tetraethylsilicate, sodium fluoride, and cetylpyridinium chloride at different concentrations were used. It is shown that fissure penetration occurs when a certain minimum content of surface-active agent is present. Fissure penetration is achieved within 3-4 s, according to the fissure morphology.

Red, green, blue and white light upconversion emission in Yb3+/Tm3+/Ho3+ co-doped tellurite glasses

International Nuclear Information System (INIS)

Desirena, H; De la Rosa, E; Meza, O; Salas, P

2011-01-01

Several Yb 3+ /Tm 3+ /Ho 3+ co-doped transparent TeO 2 -ZnO-Na 2 O-Yb 2 O 3 -Ho 2 O 3 -Tm 2 O 3 glasses were prepared and luminescence properties were characterized. Simultaneous red, green and blue (RGB) emission were obtained after excitation at 970 nm. Colour emission was tuned from multicolour to white light with colour coordinate (0.32, 0.33) matching very well with the white reference (0.33, 0.33). Changes in colour emission were obtained by varying the intensity ratios between RGB bands that are strongly concentration dependent because of the interaction of co-dopants. The colour tunability, high quality of white light and high intensity of the emitted signal make these transparent glasses excellent candidates for applications in solid-state lighting.

A comprehensive phononics of phonon assisted energy transfer in the Yb{sup 3+} aided upconversion luminescence of Tm{sup 3+} and Ho{sup 3+} in solids

Energy Technology Data Exchange (ETDEWEB)

Debnath, Radhaballabh, E-mail: drdebnathr@gmail.com; Bose, Saptasree

2015-05-15

The theory of phonon assisted energy transfer is being widely used to explain the Yb{sup 3+} ion aided normal and upconversion emission of various rare earth ions in different Yb{sup 3+} co-doped solids. The reported phonon dynamics in many of these studies are either incomplete or erroneous. Here we report Yb{sup 3+} aided upconversion luminescence properties of Tm{sup 3+} and Ho{sup 3+} in (Yb{sup 3+}/Tm{sup 3+}) and (Yb{sup 3+}/Ho{sup 3+}) co-doped two BaO–tellurite glasses and explain their phononics in the light of Dexter's theory by proposing a comprehensive scheme. The approach is valid for other systems of different phonon structures. - Highlights: • Yb{sup 3+} aided upconversion luminescence properties of Tm{sup 3+} and Ho{sup 3+} in (Yb{sup 3+}/Tm{sup 3+}) and (Yb{sup 3+}/Ho{sup 3+}) co-doped two BaO–tellurite glasses, are reported. • Phonon assisted energy transfer in these systems are explained in the light of Dexter's theory by proposing a comprehensive scheme of phononics. • The approach is valid for other systems of different phonon structures.

Impact of Drinking Water Fluoride on Human Thyroid Hormones: A Case- Control Study.

Science.gov (United States)

Kheradpisheh, Zohreh; Mirzaei, Masoud; Mahvi, Amir Hossein; Mokhtari, Mehdi; Azizi, Reyhane; Fallahzadeh, Hossein; Ehrampoush, Mohammad Hassan

2018-02-08

The elevated fluoride from drinking water impacts on T 3 , T 4 and TSH hormones. The aim was study impacts of drinking water fluoride on T 3 , T 4 and TSH hormones inYGA (Yazd Greater Area). In this case- control study 198 cases and 213 controls were selected. Fluoride was determined by the SPADNS Colorimetric Method. T 3 , T 4 and TSH hormones tested in the Yazd central laboratory by RIA (Radio Immuno Assay) method. The average amount of TSH and T 3 hormones based on the levels of fluoride in two concentration levels 0-0.29 and 0.3-0.5 (mg/L) was statistically significant (P = 0.001 for controls and P = 0.001 for cases). In multivariate regression logistic analysis, independent variable associated with Hypothyroidism were: gender (odds ratio: 2.5, CI 95%: 1.6-3.9), family history of thyroid disease (odds ratio: 2.7, CI 95%: 1.6-4.6), exercise (odds ratio: 5.34, CI 95%: 3.2-9), Diabetes (odds ratio: 3.7, CI 95%: 1.7-8), Hypertension (odds ratio: 3.2, CI 95%: 1.3-8.2), water consumption (odds ratio: 4, CI 95%: 1.2-14). It was found that fluoride has impacts on TSH, T 3 hormones even in the standard concentration of less than 0.5 mg/L. Application of standard household water purification devices was recommended for hypothyroidism.

Histopathological Effects of Varied Fluoride Concentration on Cerebrum in Albino Rats

Directory of Open Access Journals (Sweden)

Sajad Hamid

2012-02-01

Full Text Available Fluorides have been a cause of concern for scientists and environmentalists for the long because of their harmful effects on the human and animal life but the problem was highlighted during the twentieth century because of great increase in the human population and industrialization. Since fluorides accumulate in calcified and hard tissues of the body such as bone and teeth and can be detected easily in these tissues, so most of the previous studies focused on the effects of fluorides on these tissues. However, during the past decade researchers all over the world have felt that there is a need to study the effects of fluorides on various other tissues of the body including CNS as fluoride intake for prolonged period is known to cause abnormal behavioural pattern, grave implications for Alzheimer’s Disease, Dementia, Attention deficit disorder and reduced I.Q in children as the fluorides are known to cross blood brain barrier. Hence the present study has thrown light on the involvement of brain in chronic fluoride toxicity. The target organ of studied was cerebrum. In the Study, albino rats were exposed to 30 or 100 ppm fluoride (asNaF in drinking water for 3 months. Rats exposed to 30 ppm fluoride did not show any notable alterations in brain histology, whereas rats exposed to 100 ppm fluoride showed significant neurodegenerative changes in lhe motor cortex.Changes included decrease in size and number of neurons in all the regions, signs of chromatolysis and gliosis in the motor cortex. These histological changes suggest a toxic effect of high-fluoride intake & on chronic use. [J Interdiscipl Histopathol 2012; 1(1.000: 30-34

Spectral properties and anti-Stokes luminescence of TeO2-BaF2:Ho3+, Ho3+/Yb3+ ceramics and glass excited by 1.9-μm radiation of a Tm:LiYF4 laser

Science.gov (United States)

Savikin, A. P.; Egorov, A. S.; Budruev, A. V.; Perunin, I. Yu.; Krasheninnikova, O. V.; Grishin, I. A.

2017-07-01

We demonstrate the up-conversion of Tm:LiYF4 infrared (IR) laser radiation with 1908-nm wavelength into visible light with a spectral maximum at 650 nm by ceramics with a composition of (100 - x)TeO2- xBaF2 - 1 wt % HoF3- yYbF3, where x = 20, 30, or 40 mol % and y = 0 or 0.5 wt %. The samples of 60TeO2-40BaF2 - 1 wt % HoF3 - 0.5 wt % YbF3 exhibited anti-Stokes luminescence at a threshold radiation power density of 1.0-1.5 W cm-2.

Industrial fluoride pollution: chronic fluoride poisoning in Cornwall Island cattle

Energy Technology Data Exchange (ETDEWEB)

Krook, L.; Maylin, G.A.

1979-04-01

An aluminum plant on the south bank of the St. Lawrence River, southwest of Cornwall Island, Ontario, Canada, has emitted 0.816 metric tons of fluoride daily since 1973. Considerably higher amounts were emitted from 1959 to 1973. The plant was designated as the major source of fluoride emissions impacting on Cornwall Island. Cattle located on this island showed signs of chronic fluoride poisoning. This poisoning was manifested clinically by stunted growth and dental fluorosis to a degree of severe interference with drinking and mastication. This Cornwall Island herds study indicates that the established tolerance level of fluoride for performance of dairy and beef cattle is not valid since the tolerance level was set based on experiments with healthy calves which were exposed to dietary fluoride from 3 to 4 months of age and not on cattle which were chronically exposed to fluoride from conception to death. 56 references.

The reaction of fluorine atoms with methanol: yield of CH3O/CH2OH and rate constant of the reactions CH3O + CH3O and CH3O + HO2.

Science.gov (United States)

Assaf, Emmanuel; Schoemaecker, Coralie; Vereecken, Luc; Fittschen, Christa

2018-04-25

Xenondifluoride, XeF2, has been photolysed in the presence of methanol, CH3OH. Two reaction pathways are possible: F + CH3OH → CH2OH + HF and F + CH3OH → CH3O + HF. Both products, CH2OH and CH3O, will be converted to HO2 in the presence of O2. The rate constants for the reaction of both radicals with O2 differ by more than 3 orders of magnitude, which allows an unequivocal distinction between the two reactions when measuring HO2 concentrations in the presence of different O2 concentrations. The following yields have then been determined from time-resolved HO2 profiles: φCH2OH = (0.497 ± 0.013) and φCH3O = (0.503 ± 0.013). Experiments under low O2 concentrations lead to reaction mixtures containing nearly equal amounts of HO2 (converted from the first reaction) and CH3O (from the second reaction). The subsequent HO2 decays are very sensitive to the rate constants of the reaction between these two radicals and the following rate constants have been obtained: k(CH3O + CH3O) = (7.0 ± 1.4) × 10-11 cm3 s-1 and k(CH3O + HO2) = (1.1 ± 0.2) × 10-10 cm3 s-1. The latter reaction has also been theoretically investigated on the CCSD(T)//M06-2X/aug-cc-pVTZ level of theory and CH3OH + O2 have been identified as the main products. Using μVTST, a virtually pressure independent rate constant of k(CH3O + HO2) = 4.7 × 10-11 cm3 s-1 has been obtained, in good agreement with the experiment.

Fluoride release, recharge and flexural properties of polymethylmethacrylate containing fluoridated glass fillers.

Science.gov (United States)

Al-Bakri, I A; Swain, M V; Naoum, S J; Al-Omari, W M; Martin, E; Ellakwa, A

2014-06-01

The purpose of this study was to investigate the effect of fluoridated glass fillers on fluoride release, recharge and the flexural properties of modified polymethylmethacrylate (PMMA). Specimens of PMMA denture base material with various loading of fluoridated glass fillers (0%, 1%, 2.5%, 5% and 10% by weight) were prepared. Flexural properties were evaluated on rectangular specimens (n = 10) aged in deionized water after 24 hours, 1 and 3 months. Disc specimens (n = 10) were aged for 43 days in deionized water and lactic acid (pH 4.0) and fluoride release was measured at numerous intervals. After ageing, specimens were recharged and fluoride re-release was recorded at 1, 3 and 7 days after recharge. Samples containing 2.5%, 5% and 10% glass fillers showed significantly (p glass fillers specimens. All experimental specimens exhibited fluoride release in both media. The flexural strength of specimens decreased in proportion to the percentage filler inclusion with the modulus of elasticity values remaining within ISO Standard 1567. The modified PMMA with fluoridated glass fillers has the ability to release and re-release fluoride ion. Flexural strength decreased as glass filler uploading increased. © 2014 Australian Dental Association.

DFT study of the interaction between 3-nitro-1,2,4-triazole-5-one and hydrogen fluoride

International Nuclear Information System (INIS)

Fang Guoyong; Xu Lina; Hu Xingen; Li Xinhua

2008-01-01

Three fully optimized geometries of 3-nitro-1,2,4-triazol-5-one-hydrogen fluoride (NTO-HF) complexes have been obtained with density functional theory (DFT) method at the B3LYP/6-311++G** level. The intermolecular interaction energy is calculated with zero point energy (ZPE) correction and basis set superposition error (BSSE) correction. The greatest corrected intermolecular interaction of the NTO-HF complexes is -34.155 kJ/mol. Electrons in complex systems transfer from NTO to HF. Natural bond orbital (NBO) analysis is performed to reveal the origin of the interaction. The strong hydrogen bonds contribute to the interaction energies dominantly. Frequency calculations are carried out on each optimized structure, and their IR spectra are discussed. Vibrational analysis show that there are large red-shifts for H-X (X = N and F) stretching vibrational frequencies in the NTO and hydrogen fluoride complexes. The changes of thermodynamic properties from the monomer to complexes with the temperature ranging from 200 K to 1500 K have been obtained using the statistical thermodynamic method. It is found that two of three NTO-HF complexes can be produced spontaneously from NTO and HF at room temperature

DFT study of the interaction between 3-nitro-1,2,4-triazole-5-one and hydrogen fluoride

Energy Technology Data Exchange (ETDEWEB)

Fang Guoyong [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Xu Lina [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China)], E-mail: ahxulina@sohu.com; Hu Xingen; Li Xinhua [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China)

2008-12-15

Three fully optimized geometries of 3-nitro-1,2,4-triazol-5-one-hydrogen fluoride (NTO-HF) complexes have been obtained with density functional theory (DFT) method at the B3LYP/6-311++G** level. The intermolecular interaction energy is calculated with zero point energy (ZPE) correction and basis set superposition error (BSSE) correction. The greatest corrected intermolecular interaction of the NTO-HF complexes is -34.155 kJ/mol. Electrons in complex systems transfer from NTO to HF. Natural bond orbital (NBO) analysis is performed to reveal the origin of the interaction. The strong hydrogen bonds contribute to the interaction energies dominantly. Frequency calculations are carried out on each optimized structure, and their IR spectra are discussed. Vibrational analysis show that there are large red-shifts for H-X (X = N and F) stretching vibrational frequencies in the NTO and hydrogen fluoride complexes. The changes of thermodynamic properties from the monomer to complexes with the temperature ranging from 200 K to 1500 K have been obtained using the statistical thermodynamic method. It is found that two of three NTO-HF complexes can be produced spontaneously from NTO and HF at room temperature.

White upconversion luminescence in Tm3+/Ho3+/Yb3+ triply doped K+-Na+ ion-exchanged aluminum germanate glass channel waveguide

Science.gov (United States)

Liu, Xiao; Chen, Baojie; Pun, Edwin Yue Bun; Lin, Hai

2013-01-01

Rare-earth ions doped K+-Na+ ion-exchanged aluminum germanate (NMAG) glass channel waveguides have been designed and fabricated. Under 980 nm laser pumping, an intense upconversion white light transmission trace was observed in Tm3+/Ho3+/Yb3+ triply doped NMAG glass channel waveguide and a high-brightness light spot was achieved from the output end of the fiber connected to the waveguide channel. The fluorescent colors were diverse and located within or near the white region in CIE chromaticity diagram under various pumping powers. These admirable results indicate that Tm3+/Ho3+/Yb3+ triply doped NMAG channel waveguide is a promising light source for medical and high-precision processing illumination.

Fluoride absorption: independence from plasma fluoride levels

International Nuclear Information System (INIS)

Whitford, G.M.; Williams, J.L.

1986-01-01

The concept that there are physiologic mechanisms to homeostatically regulate plasma fluoride concentrations has been supported by results in the literature suggesting an inverse relationship between plasma fluoride levels and the absorption of the ion from the gastrointestinal tract of the rat. The validity of the relationship was questioned because of possible problems in the experimental design. The present work used four different methods to evaluate the effect of plasma fluoride levels on the absorption of the ion in rats: (i) the percentage of the daily fluoride intake that was excreted in the urine; (ii) the concentration of fluoride in femur epiphyses; (iii) the net areas under the time-plasma fluoride concentration curves after intragastric fluoride doses; and (iv) the residual amounts or fluoride in the gastrointestinal tracts after the intragastric fluoride doses. None of these methods indicated that plasma fluoride levels influence the rate or the degree or fluoride absorption. It was concluded that, unless extremely high plasma fluoride levels are involved (pharmacologic or toxic doses), the absorption of the ion is independent of plasma levels. The results provide further evidence that plasma fluoride concentrations are not homeostatically regulated

Synthesis and characterization of composites HoMn_1_-_x(Ni,Co)_xO_3

International Nuclear Information System (INIS)

Santos, Cassio Morilla dos

2011-01-01

In this work was accomplished the synthesis process and structural and magnetic characterization of HoMn_1_-_X(Ni,Co)_XO_3 compounds of perovskite structure. The samples synthesis were performed through modified polymeric precursor method. After synthesis and solvent removal, the polymer resin formed was treated at 350 deg C/4h for organic constituents removal, followed by heating treatment at 500 deg C/4h and 900 deg C/20h to obtain the crystalline phase. For structural characterization, it was used D10B-XPD beam line of Laboratorio Nacional de Luz Sincrotron (LNLS), where X-rays wavelengths below cobalt, manganese and nickel absorption edge, were used. The formation of HoNi_0_._5_0Mn_0_._5_0O_3, HoCo_0_._5_0Mn_0_._5_0O_3 and HoNi_0_._2_5Co_0_._2_5Mn_0_._5_0O_3 phases were observed by X-ray diffraction technique. By Rietveld refinement method for sample HoNi_0_._2_5Co_0_._2_5Mn_0_._5_0O_3, it was determined that cobalt and nickel had similar occupations at the top and bottom of unit cell, while the manganese preferentially occupied plan 002. The magnetic response of samples was studied through magnetization curves according to the temperature function and the applied magnetic field. The ZFC curves showed a paramagnetic response associated to holmium magnetic moment, and ferromagnetism, antiferromagnetism and ferrimagnetism coexistence, due to sublattices formed by transition metals. The FC curves evidenced the spin reversal phenomenon, associated to the interaction between the sublattice formed by transition metals with sublattices formed by rare-earth, considering a mechanism of antiferromagnetic exchange interaction. (author)

Effects of the Ho{sup 3+}/Yb{sup 3+} concentration ratio on the structure and photoluminescence of ZnO films

Energy Technology Data Exchange (ETDEWEB)

Xu, Boxu [School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Wang, Pei [Auditing Department, Tianjin Polytechnic University, Tianjin 300387 (China); Meng, Xiaoqi; Zou, Kaishun [School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Liu, Juncheng, E-mail: jchliu@tjpu.edu.cn [School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

2016-07-15

To improve the efficiency of photoluminescent films, this study investigates the effects of the Ho{sup 3+}/Yb{sup 3+} concentration ratio on the structure and up-conversion photoluminescence of ZnO films prepared by the sol–gel method and the spin-coating technique. ZnO maintained its hexagonal wurtzite structure after doping with rare earth ions. The ZnO films consist of round granules, the average size of which increases as the Ho{sup 3+}/Yb{sup 3+} concentration ratio increases. Once the ratio exceeds 1:2, the film's granules significantly coarsen, and the surface roughness slightly increases. When the film is pumped with a 980-nm laser, two intense emission bands are observed in the up-conversion emission spectrum, with a green band centered at 550 nm and a red band centered at 660 nm, corresponding to the Ho{sup 3+}: {sup 5}S{sub 2}/{sup 5}F{sub 4}→{sup 5}I{sub 8}, and {sup 5}F{sub 5}→{sup 5}I{sub 8} transitions, respectively. In addition, as the Ho{sup 3+}/Yb{sup 3+} concentration ratio increases, the intensity of the film's upconversion luminescence first increases and then decreases, reaching a maximum at a concentration ratio of 1:2, with a peak of about four times the minimum value.

Positive and negative exchange bias effects from magnetization reversal in Ho{sup 3+} doped YFe{sub 0.5}Cr{sub 0.5}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Shi, L.R., E-mail: shiliran1127@126.com [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Wei, C.X.; Wang, Z.; Ju, L.; Xu, T.S.; Li, T.X.; Yan, X.W. [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Xia, Z.C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

2017-07-01

Highlights: • The dual magnetization reversal is observed in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. • The EB field transforms from negative to positive and then to negative. • A large exchange bias effect induced by Ho{sup 3+} doping is obtained in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. - Abstract: The polycrystalline ceramics of Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3} (x = 0, 0.05 and 0.1) are synthesized by a sol-gel method. The magnetization reversal and exchange bias effect are investigated in single phase bulk Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. Magnetic Ho{sup 3+} ion as a dopant is introduced into the system to confirm the influence of A-site ion on the magnetic interactions. The dual reversal of exchange bias field for x = 0.05 is observed, and its characteristic temperatures are corresponding to the compensation temperatures of magnetization reversal. The exchange bias field of x = 0.1 is found to be ∼10.03 kOe at 4 K, revealing a large value compared with that of x = 0. A schematic diagram based on the competition between the single ion anisotropy and Dzyaloshinsky-Moriya interaction, and the antiparallel coupling between the Ho{sup 3+} moments and the canted Cr{sup 3+}/Fe{sup 3+} moments, is used to understand the dual reversal phenomenon of magnetization and exchange bias effect.

Dynamics of ligand exchange and association processes in solutions of transition 3d-metal fluorides

International Nuclear Information System (INIS)

Nazmutdinova, G.A.; Shtyrlin, V.G.; Zakharov, A.V.; Sal'nikov, Yu.I.

1993-01-01

By 19 NMR in combination with ESR spectroscopy rate constants and activation parameters of fluoride-ion exchange reactions in solutions of VOF 5 3- and FeF 6 3- complexes were determined. Associative character of the studied reactions of ligand exchange is shown. Dependence of fluoride complex reactivity on the charge, electron structure of the central ion and formation of hydrogen bonds of coordinated F - ions with solvent molecules was demonstrated. Stability constants, rates of formation and dissociation of intercomplex associates in fluoride solutions were ascertained

The system HoCl3-YCl3-H2O (25 deg C)

International Nuclear Information System (INIS)

Sorokina, A.A.; Yudina, N.G.

1981-01-01

By solubility method the system HoCl 3 -YCl 3 -H 2 O at 25 deg C has been studied. It is shown that in this system the continuous serie of solid solutions is formed. The liquid solutions of this system have been investigated by the isopiestic method. The values of activity coefficients, activity, free energy formation and excess free energy of solid solutions are calculated [ru

Effective tuning of the ratio of red to green emission of Ho"3"+ ions in single LiLuF_4 microparticle via codoping Ce"3"+ ions

International Nuclear Information System (INIS)

Gao, Wei; Dong, Jun; Liu, Jihong; Yan, Xuewen

2016-01-01

Yb"3"+/Ho"3"+ codoped LiLuF_4 microparticles have been successfully prepared via a facile hydrothermal method. The crystal phase and morphology of LiLuF_4 microparticles were inspected by x-ray diffraction and scanning electron microscope, respectively. The upconversion emission of single LiLuF_4: Yb"3"+/Ho"3"+ microparticle was carefully studied by a confocal microscopy setup under NIR 980 nm excitation. With the increase of Ce"3"+ ion concentrations of 12%, the ratio of red to green emission of the Ho"3"+ ions of single LiLuF_4 microparticle was boosted about 17-fold, and the output colors were tuned from green to red, which is due to the two efficient cross-relaxation between Ho"3"+ and Ce"3"+ ions enhances the red and suppresses the green in the emission processes. To investigate the optical properties of the single microparticle or nanoparticle through the confocal microscopy setup can effectively avoid the influence of surrounding particle or environment, and could provide more precise information for better exploring the emission mechanisms of rare earth ions. The tunable upconversion emission of Ho"3"+ in single LiLuF_4 microparticle in this work will have great potential applications in the micro optoelectronic devices and color display applications. - Highlights: • The optical properties of the single LiLuF4: Yb3+/Ho3+/Ce3+ microparticle were studied. • The output colors of single LiLuF4 microparticle were tuned from green to red. • The upconversion mechanisms between Ho3+ and Ce3+ ions were discussed based on emission spectrum.

Studies of the energy transfer processes from Er3+ and Ho3+ to Nd3+, Tb3+ or Eu3+ in LiYF4 crystal and ZBLAN glass for the laser media optimization operating near 3μm region

International Nuclear Information System (INIS)

Jagosich, Fabio Henrique

2006-01-01

The energy transfer processes (ET) from the 4 I 13/2 ; 4 I 11/2 levels of Er 3+ and 5 I 6 levels of Ho 3+ ions in LiYF 4 (YLF) crystal and ZBLAN glass to Nd 3+ , Tb 3+ or Eu 3+ deactivators ions were studied. The micro parameters of these energy transfer processes were determined using the overlap integral method, and showed that Eu 3+ ion is the best deactivator of the first excited state of the Ho 3+ in YLF, and Nd 3+ is the best deactivator of the Er 3+ in YLF and ZBLAN materials. The 1.5 and 2.7μm emissions of Er 3+ and 2.1 and 2.9μm fluorescence of Ho 3+ were measured using short laser pulses excitations from a tunable OPO pumped 2w-Nd:YAG laser system. We proposed a criterion for discriminating the energy transfer processes assisted by excitation migration (diffusion or hopping) among donors. It was observed that diffusion model describes the ET process from the second excited state of the donor (Er 3+ or Ho 3+ ) independently of the C D-D /C D-A ratio, while the hopping model can describe the ET process involving the first excited state of donor. We proposed a modification of the hopping model in order to describe the experimental results for systems having C D-D /C D-A ≥ 10. Using the ET parameters, we determined that the best systems for laser action at 3μm are the Ho:Eu:YLF, Ho:Nd:YLF and Er:Nd:YLF systems. On the other hand, we found that Er 3+ doped (1.5 mol%) ZBLAN glasses, single and co-doped with Nd 3+ , Tb 3+ or Eu 3+ , do not show potential for laser action at 2.8μm. The up-conversion processes were studied in Er:YLF systems as a function of the Er 3+ concentration, and the excited state absorption (ESA) and up conversion by energy transfer (ETU) processes were discriminated using a time resolved fluorescence decays. It was observed that 980 nm is the most convenient wavelength for pumping the Er:YLF system for quasi cw laser operation at 2.8μm. The pump-probe technique was used to investigate the lifetime effects in Er:YLF system showing

Fluoride Rinses, Gels and Foams

DEFF Research Database (Denmark)

Twetman, Svante; Keller, Mette K

2016-01-01

AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after...... (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse......, moderate for fluoride gel and very low for acidulated fluoride foam. No conclusions could be drawn on the cost-effectiveness. CONCLUSIONS: This review, covering the recent decade, has further substantiated the evidence for a caries-preventive effect of fluoride mouth rinse, fluoride gel and foam...

Beryllium fluoride exchange rate accelerated by Mg²⁺ as discovered by ¹⁹F NMR.

Science.gov (United States)

Liu, Yixiang; Mao, Xi-an; Liu, Maili; Jiang, Ling

2015-01-08

Beryllium fluoride is widely used as a phosphoryl analogue in macromolecular studies, which are not only fluoride-sensitive but also magnesium-dependent. The beryllium fluorides are a mixture of different species including BeF3(-) and BeF4(2-) exchanging under thermodynamic equilibrium in neutral aqueous solutions. In the cases of mimicking phosphate group transfer, both beryllium fluoride and the magnesium ion are generally needed. However, the impact of magnesium on the bioactivity of beryllium fluoride is not clear. We have found by (19)F NMR spectroscopy that Mg(2+) can severely affect the chemical exchange kinetics between BeF3(-) and BeF4(2-). When the F(-) concentration is relatively low, the presence of 10.0 mM Mg(2+) can accelerate the exchange rate 3-4 fold. However, when the F(-) concentration is relatively high, the Mg(2+) effect on the chemical exchange vanishes. On the basis of these findings, we proposed a possible mechanism that BeF4(2-) and Mg(2+) form an ion pair that affects the distribution of beryllium fluoride species and thus the activity in the solution.

Structural properties and sensing characteristics of high-k Ho2O3 sensing film-based electrolyte-insulator-semiconductor

International Nuclear Information System (INIS)

Pan, Tung-Ming; Huang, Ming-De

2011-01-01

Highlights: → We report the structural properties and sensing characteristics of Ho 2 O 3 sensing membranes deposited on Si substrates by reactive sputtering. → We applied X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy to study the structural and morphological features of these films after they had been subjected to annealing at various temperatures (700 deg. C, 800 deg. C, and 900 deg. C). → The Ho 2 O 3 electrolyte-insulator-semiconductor device annealed at 800 deg. C exhibited a higher sensitivity, a lower hysteresis voltage, and a smaller drift rate than other annealing temperatures. - Abstract: In this study, we report a Ho 2 O 3 electrolyte-insulator-semiconductor (EIS) device films deposited on Si substrates through reactive sputtering. The effect of thermal annealing (700, 800, and 900 deg. C) on the structural and surface properties of Ho 2 O 3 sensing film was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy. We found that the EIS device with a Ho 2 O 3 sensing film annealed at 800 deg. C exhibited a higher sensitivity of ∼57 mV/pH, a lower hysteresis voltage of 2.68 mV, and a smaller drift rate of 2.83 mV h -1 compared to those at other annealing conditions. This improvement can be attributed to the well-crystallized Ho 2 O 3 structure and the large surface roughness.

Rare-Earth Oxide Ion (Tm3+, Ho3+, and U3+) Doped Glasses and Fibres for 1.8 to 4 Micrometer Coherent and Broadband Sources

Science.gov (United States)

2006-07-24

oxide ( TeO2 ) , fluorine- containing silicate (SiOF2) and germanate (GeOF2) glass hosts for each dopant by characterising the spectroscopic properties...Earth Oxide Ion (Tm3+, Ho3+, And U3+) Doped Glasses And Fibres For 1.8 To 4 Micrometer Coherent And Broadband Sources 5c. PROGRAM ELEMENT NUMBER 5d...Rare-earth oxide ion (Tm3+, Ho3+, and U3+) doped glasses and fibres for 1.8 to 4 micrometer coherent and broadband sources Report prepared

Silver diamine fluoride: a caries "silver-fluoride bullet".

Science.gov (United States)

Rosenblatt, A; Stamford, T C M; Niederman, R

2009-02-01

The antimicrobial use of silver compounds pivots on the 100-year-old application of silver nitrate, silver foil, and silver sutures for the prevention and treatment of ocular, surgical, and dental infections. Ag(+) kills pathogenic organisms at concentrations of linings, water purification systems, hospital gowns, and caries prevention. To distill the current best evidence relative to caries, this systematic review asked: Will silver diamine fluoride (SDF) more effectively prevent caries than fluoride varnish? A five-database search, reference review, and hand search identified 99 human clinical trials in three languages published between 1966 and 2006. Dual review for controlled clinical trials with the patient as the unit of observation, and excluding cross-sectional, animal, in vitro studies, and opinions, identified 2 studies meeting the inclusion criteria. The trials indicated that SDF's lowest prevented fractions for caries arrest and caries prevention were 96.1% and 70.3%, respectively. In contrast, fluoride varnish's highest prevented fractions for caries arrest and caries prevention were 21.3% and 55.7%, respectively. Similarly, SDF's highest numbers needed to treat for caries arrest and caries prevention were 0.8 (95% CI=0.5-1.0) and 0.9 (95% CI=0.4-1.1), respectively. For fluoride varnish, the lowest numbers needed to treat for caries arrest and prevention were 3.7 (95% CI=3.4-3.9) and 1.1 (95% CI=0.7-1.4), respectively. Adverse events were monitored, with no significant differences between control and experimental groups. These promising results suggest that SDF is more effective than fluoride varnish, and may be a valuable caries-preventive intervention. As well, the availability of a safe, effective, efficient, and equitable caries-preventive agent appears to meet the criteria of both the WHO Millennium Goals and the US Institute of Medicine's criteria for 21st century medical care.

Pulsed laser deposited KY3F10: Ho3+ thin films: Influence of target to substrate

CSIR Research Space (South Africa)

Debelo, NG

2017-04-01

Full Text Available The influence of target to substrate distance (dts) on the structural, morphological and photoluminescence (PL) properties of commercially obtained KY3F10 : Ho3+ phosphor thin films prepared by pulsed laser deposition is investigated for dts values...

Spinal metastases of malignant gliomas; Spinale Metastasierung bei malignen Gliomen. Zwei Fallbeschreibungen

Energy Technology Data Exchange (ETDEWEB)

Materlik, B; Steidle-Katic, U; Feyerabend, T; Richter, E [Medizinische Univ. Luebeck (Germany). Klinik fuer Strahlentherapie und Nuklearmedizin; Wauschkuhn, B [Medizinische Univ. Luebeck (Germany). Klinik fuer Neurologie

1998-09-01

Purpose: Extracranial metastases of malignant gliomas are rare. We report 2 cases with spinal metastases in patients suffering from glioma. Patients and Method: Two patients (33 and 57 years old) developed spinal canal metastases of a glioblastoma multiforme and anaplastic astrocytoma Grade III respectively 25 and 9 months after surgical resection and radiotherapy. Both metastases were confirmed pathohistologically. Results: Intraspinal metastases were irradiated with a total dose of 12.6 Gy and 50 Gy. Treatment withdrawal was necessary in one patient due to reduced clinical condition. Regression of neurological symptoms was observed in the second patient. Conclusions: Spinal spread of malignant glioma should be considered during care and follow-up in glioma patients with spinal symptoms. (orig.) [Deutsch] Hintergrund: Maligne Gliome metastasieren aeusserst selten extrakraniell. Wir stellen zwei Faelle einer spinalen Filialisierung bei Gliompatienten vor. Patientengut und Methode: Zwei Patienten (33 und 57 Jahre alt) entwickelten 25 bzw. neun Monate nach Resektion und postoperativer Radiatio eines Glioblastoma multiforme und eines anaplastischen Astrozytoms WHO-Grad III histologisch gesicherte intraspinale Metastasen, welche durch Sensibilitaetsstoerungen der Beine symptomatisch wurden. Ergebnisse: Die intraspinalen Filiae wurden mit 12,6 Gy bzw. 50 Gy bestrahlt. Bei einem Patienten musste die Radiatio wegen zunehmender Verschlechterung des Allgemeinzustandes abgebrochen werden, bei dem zweiten Patienten besserte sich die neurologische Symptomatik. Schlussfolgerung: Bei der Betreuung von Gliompatienten sollte, insbesondere in der Nachsorge, an die Moeglichkeit der spinalen Metastasierung mit entsprechender Symptomatik gedacht werden. (orig.)

Ho:YAG laser: intervertebral disk cell interaction using three-dimensional cell culture system

Science.gov (United States)

Sato, Masato; Ishihara, Miya; Arai, Tsunenori; Asazuma, Takashi; Kikuchi, Toshiyuki; Kikuchi, Makoto; Fujikawa, Kyosuke

2000-06-01

The purpose of this study is to evaluate the influence on the intervertebral disc cells after laser irradiation using three- dimensional culture system and to clarify the optimum Ho:YAG laser irradiation condition on percutaneous laser disc decompression (PLDD) for lumbar disc herniation. Since the Ho:YAG laser ablation is characterized by water-vapor bubble dynamics, not only thermal effect but also acoustic effect on cell metabolism might occur in the intervertebral disc. We studied the disc cell reaction from the metabolic point of view to investigate photothermal and photoacoustic effects on three-dimensional cultured disc cell. Intervertebral discs were obtained from female 30 Japanese white rabbits weighing about 1 kg. A pulsed Ho:YAG laser (wavelength: 2.1 micrometer, pulse width: about 200 microseconds) was delivered through a 200 micrometer-core diameter single silica glass fiber. We used the Ho:YAG laser irradiation fluence ranging from 60 to approximately 800 J/cm2 at the fiber end. To investigate acoustic effect, the acoustic transducer constructed with polyvinylidene fluoride (PVdF) film and acoustic absorber was used to detect the stress wave. Thermocouple and thermography were used to investigate thermal effect. Concerning damage of plasma membrane and ability of matrix synthesis, thermal effect might mainly affect cell reaction in total energy of 54 J (closed to practically used condition), but in 27 J, acoustic effect might contribute to it. We found that total energy was key parameter among the optimum condition, so that temperature and/or stress wave may influence Ho:YAG laser-disc cell interactions.

Magnetic interactions in HoCr{sub 1-x}Fe{sub x}O{sub 3} (x = 0, 0.2) investigated by neutron powder diffraction

Energy Technology Data Exchange (ETDEWEB)

Liu, Xinzhi, E-mail: liuxinzhi1984.cn@163.com [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Hao, Lijie; Ma, Xiaobai [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Wang, Chin-Wei [Neutron Group, National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan (China); Klose, Frank [Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Liu, Yuntao, E-mail: ytliu@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Sun, Kai; Li, Yuqing [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Chen, Dongfeng, E-mail: dongfeng@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China)

2017-07-01

Highlights: • The temperature dependent magnetism of HoCr{sub 1-x}Fe{sub x}O{sub 3} (x = 0, 0.2) were investigated by neutron diffraction. • Cr{sup 3+} moment follows a mean field theory while Ho{sup 3+} follows a spin 1/2 model. • An magneto-elastic strain was observed accompanying with the ordering of Cr{sup 3+}. - Abstract: The temperature dependent magnetism of Fe-doped rare earth orthochromite HoCr{sub 1-x}Fe{sub x}O{sub 3}(x = 0, 0.2) was investigated by neutron powder diffraction. It is found that the magnetism of Cr(Fe){sup 3+} can be well understood within mean field theory, while the ordering of Ho{sup 3+} was induced by the Cr(Fe){sup 3+} sublattice and can be satisfyingly described by an effective S = 1/2 model. The absences of both the most common G{sub x}F{sub z} configuration of Cr{sup 3+} and the ordering of Ho{sup 3+} caused by Ho-Ho interaction evidence a strong Ho{sup 3+}-Cr{sup 3+} interaction which dominates this system. On the other hand, a remarkable magnetoelastic strain was observed accompanying the Cr(Fe){sup 3+} ordering. An analysis based on the equation of state with a Grüneisen approximation was performed and revealed magnetic origin of this strain.

Fluoride varnish or fluoride mouth rinse?

DEFF Research Database (Denmark)

Keller, M K; Klausen, BJ; Twetman, S

2016-01-01

OBJECTIVE: In many Danish communities, school-based fluoride programs are offered to children with high caries risk in adjunct to tooth brushing. The purpose of this field trial was to compare the caries-preventive effectiveness of two different fluoride programs in 6-12 year olds. BASIC RESEARCH...... different schools were enrolled after informed consent and their class unit was randomly allocated to one of two fluoride programs. INTERVENTIONS: One group received a semi-annual fluoride varnish applications (FV) and the other group continued with an existing program with fluoride mouth rinses once per...... in caries development over two years among children participating in a school-based fluoride varnish or mouth rinse program....

Evaluation of a redesigned 3/4-inch uranium hexafluoride cylinder valve stem

International Nuclear Information System (INIS)

Zonner, L.A.; Wamsley, S.D.

1978-01-01

The performance of a redesigned 3/4-in. uranium hexafluoride cylinder valve stem has been evaluated at the Portsmouth Gaseous Diffusion Plant. Prototypes, machined from Monel bar stock and having a 45 0 tip angle instead of the 15 0 tip angle of the standard valve stem, were fabricated. Tests included: cyclic leak evaluation; flow restriction determination; wear testing with uranyl fluoride deposits in the valve seat; stress corrosion testing; field testing (in previously rejected valve bodies); and production leak testing. Because their overall test performance was excellent, actual production usage of the redesigned stems was initiated. The in-service performance of valves fitted with redesigned stems has been significantly superior to that of valves having the standard stems: rejection rates have been 0.7 and 16.6 percent, respectively. Recommendations are made to replace all 15 0 angle tip stems presently in service with new stems having a 45 0 angle tip and to specify the new stem tip design for future 3/4-in. valve purchases

Studies of the rare earth-iron interactions in the orthoferrites GdFeO3 and HoFeO3

International Nuclear Information System (INIS)

Sakata, T.; Enomura, A.

1979-01-01

The magnetic behaviour of GdFeO 3 and HoFeO 3 is investigated by means of a Faraday type magnetic balance in a temperature range where rare earth ions are in the paramagnetic state. The results are analyzed in terms of an effective field at a rare earth ion site. Thereby the isotropic exchange field as well as the magnetic dipole field are taken into account. By this means the exchange integral, J/k(K), between an iron ion and a rare earth ion may be estimated to be 0.23 for GdFeO 3 and 0.25 for HoFeO 3 , respectively. (author)

Efficient energy extraction from a diode-pumped Q-switched Tm,Ho:YLiF4 laser

Science.gov (United States)

Mcguckin, B. T.; Menzies, R. T.; Hemmati, H.

1991-01-01

The operation of a diode-laser pumped thulium, holmium yttrium-lithium-fluoride laser (Tm,Ho:YLF) in Q-switched mode is reported. Output energies of 200 microjoules in pulses of 22 ns duration are recorded at Q-switch frequencies commensurate with an effective upper laser level lifetime of 6 ms. This lifetime is appreciably longer than that observed in other hosts permitting stored energy extraction of 64 percent, close to the projected maximum performance from these materials.

A Case of 3,4-Dimethoxyamphetamine (3,4-DMA) and 3,4-Methylenedioxymethamphetamine (MDMA) Toxicity with Possible Metabolic Interaction.

Science.gov (United States)

Darracq, Michael A; Thornton, Stephen L; Minns, Alicia B; Gerona, Roy R

2016-01-01

We present a case of "ecstasy" ingestion revealing 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-dimethoxyamphetamine (3,4-DMA) and absence of cytochrome P450 (CYP)-2D6 MDMA metabolites. A 19-year-old presented following a seizure. Initial vital signs were normal. Laboratories were normal with the exception of sodium 127 mEq/L and urine drugs of abuse screen positive for amphetamines. Twelve hours later, serum sodium was 114 mEq/L and a second seizure occurred. After receiving hypertonic saline (3%), the patient had improvement in mental status and admitted to taking "ecstasy" at a rave prior to her initial presentation. Liquid chromatography-time-of-flight mass spectrometry (LC-TOF/MS) of serum and urine revealed MDMA, 3,4-DMA, and the CYP-2B6 MDMA metabolites 3,4-methylendioxyamphetamine (MDA) and 4-hydroxy-3-methoxyamphetamine (HMA). The CYP2D6 metabolites of MDMA, 3,4-dihydromethamphetamine (HHMA) and 4-hydroxy-3-methoxymethamphetamine (HMMA), were detected at very low levels. This case highlights the polypharmacy which may exist among users of psychoactive illicit substances and demonstrates that concurrent use of MDMA and 3,4-DMA may predispose patients to severe toxicity. Toxicologists and other healthcare providers should be aware of this potential toxicity.

Density-functional study of the structures and properties of holmium-doped silicon clusters HoSi n (n = 3-9) and their anions.

Science.gov (United States)

Hou, Liyuan; Yang, Jucai; Liu, Yuming

2017-04-01

The structures and properties of Ho-doped Si clusters, including their adiabatic electron affinities (AEAs), simulated photoelectron spectra (PESs), stabilities, magnetic moments, and charge-transfer characteristics, were systematically investigated using four density-functional methods. The results show that the double-hybrid functional (which includes an MP2 correlation component) can accurately predict the ground-state structure and properties of Ho-doped Si clusters. The ground-state structures of HoSi n (n = 3-9) are sextuplet electronic states. The structures of these Ho-doped Si clusters (aside from HoSi 7 ) are substitutional. The ground-state structures of HoSi n - are quintuplet electronic states. Their predicted AEAs are in excellent agreement with the experimental ones. The mean absolute error in the theoretical AEAs of HoSi n (n = 4-9) is only 0.04 eV. The simulated PESs for HoSi n - (n = 5-9) are in good agreement with the experimental PESs. Based on its simulated PES and theoretical AEA, we reassigned the experimental PES of HoSi 4 - and obtained an experimental AEA of 2.2 ± 0.1 eV. The dissociation energies of Ho from HoSi n and HoSi n - (n = 3-9) were evaluated to test the relative stabilities of the clusters. HOMO-LUMO gap analysis indicated that doping the Si clusters with the rare-earth metal atom significantly increases their photochemical reactivity. Natural population analysis showed that the magnetic moments of HoSi n (n = 3-9) and their anions derive mainly from the Ho atom. It was also found that the magnetic moments of Ho in the HoSi n clusters are larger than the magnetic moment of an isolated Ho atom.

Selective degradation of lignin and elimination of HO radicals in pulps by O3 and UV laser flash irradiation

Institute of Scientific and Technical Information of China (English)

林鹿; 周贤涛; 邱玉桂

2002-01-01

HO radical is an aggressive reagent to abstract hydrogen from diverse substitutes and lead them to degradation, however, in reaction of active oxygen species with lignins, complex phenolic polymers, in dispersed lignocellulose such as pulp for environment-benign delignification, HO radicals should be eliminated as more as possible to prevent cellulose from unfavorably concomitant degradation. A reaction system of O3 is constructed under UV laser flash irradiation, and HO radicals are controlled efficiently by it. A new mechanism is proposed, for the first time, that O radicals generated from reaction of O3 with UV laser flash irradiation might be the contributor to scavenge HO radicals.

Estimation of human absorbed dose for (166)Ho-PAM: comparison with (166)Ho-DOTMP and (166)Ho-TTHMP.

Science.gov (United States)

Vaez-Tehrani, Mahdokht; Zolghadri, Samaneh; Yousefnia, Hassan; Afarideh, Hossein

2016-10-01

In this study, the human absorbed dose of holmium-166 ((166)Ho)-pamidronate (PAM) as a potential agent for the management of multiple myeloma was estimated. (166)Ho-PAM complex was prepared at optimized conditions and injected into the rats. The equivalent and effective absorbed doses to human organs after injection of the complex were estimated by radiation-absorbed dose assessment resource and methods proposed by Sparks et al based on rat data. The red marrow to other organ absorbed dose ratios were compared with these data for (166)Ho-DOTMP, as the only clinically used (166)Ho bone marrow ablative agent, and (166)Ho-TTHMP. The highest absorbed dose amounts are observed in the bone surface and bone marrow with 1.11 and 0.903 mGy MBq(-1), respectively. Most other organs would receive approximately insignificant absorbed dose. While (166)Ho-PAM demonstrated a higher red marrow to total body absorbed dose ratio than (166)Ho-1,4,7,10-tetraazacyclo dodecane-1,4,7,10 tetra ethylene phosphonic acid (DOTMP) and (166)Ho-triethylene tetramine hexa (methylene phosphonic acid) (TTHMP), the red marrow to most organ absorbed dose ratios for (166)Ho-TTHMP and (166)Ho-PAM are much higher than the ratios for (166)Ho-DOTMP. The result showed that (166)Ho-PAM has significant characteristics than (166)Ho-DOTMP and therefore, this complex can be considered as a good agent for bone marrow ablative therapy. In this work, two separate points have been investigated: (1) human absorbed dose of (166)Ho-PAM, as a potential bone marrow ablative agent, has been estimated; and (2) the complex has been compared with (166)Ho-DOTMP, as the only clinically used bone marrow ablative radiopharmaceutical, showing significant characteristics.

In vitro evaluation of fluoride products in the development of carious lesions in deciduous teeth.

Science.gov (United States)

Santos, Lucineide de Melo; Reis, José Ivo Limeira dos; Medeiros, Maria Perolina de; Ramos, Sheyla Moreira; Araújo, Juliane Mendes de

2009-01-01

The purpose of this study was to evaluate the effect of the application of fluoride products on the development of enamel caries in deciduous teeth. A total of 108 deciduous teeth were chosen for the study. Acid-resistant varnish was applied on the teeth, leaving only one area of 5 mm x 1 mm of dental enamel exposed. The teeth were allocated randomly to one of the following groups: 1) control - toothpaste without fluoride; 2) 1.23% fluoride gel; 3) Duraflur fluoride varnish; 4) Duraphat fluoride varnish; 5) Fluorniz fluoride varnish; 6) Fluorphat fluoride varnish; 7) varnish with Duofluorid; 8) 12% silver fluoride diamine (Cariestop); 9) children's fluoride toothpaste (500 ppm). The tested products were applied on the teeth according to the manufacturer's recommendations and the teeth were stored in a moist environment for 24 hours. Each group of teeth was then subjected to a pH cycling model for 14 days, after which the teeth were cut through the center for an analysis of the depth of the carious lesion by polarized light microscopy. Comparisons were made between the treatments and the control group. The mean lesion depth values were 318 microm +/- 39 (control), 213 microm +/- 27 (fluoride gel), 203 microm +/- 34 (Duraflur), 133 microm +/- 25 (Duraphat), 207 microm +/- 27 (Fluor-niz), 212 microm +/- 27 (Fluorphat), 210 +/- 28 (Duofluorid), 146 +/- 31 (Cariestop) and 228 +/- 24 (fluoride toothpaste). None of the products used here was able to completely prevent the formation of lesions. The highest cariostatic effect was achieved by fluoride varnish Duraphat and the lowest by the fluoride toothpaste.

Clinical study of liver cancer (Hepatocellular carcinoma) by 166 Ho-CHICO

Energy Technology Data Exchange (ETDEWEB)

Lee, J. T.; Yoo, H. S.; Lee, J. D.; Lee, D. Y.; Kim, E. K.; Yoo, N. C.; Shin, S. J.; Han, K. H. [Yonsei University, Seoul (Korea); Park, K. B. [Korea Atomic Energy Research Institute, Taejeon (Korea)

2000-04-01

As having used Ho-166 Chitosan complex, this study was designed for the development of new therapeutic agent in the treatment of liver cancer (hepatocellular carcinoma). During the period of 3 years from April 1, 1997 to March 31, 2000, this project was successfully performed on the base of clinical experience with percutaneous Ho-166 CHICO injection in the treatment of liver cancer'. In order to evaluate the biodistribution and effect of Ho-166 CHICO was performed in 50 patients, who had the progressed liver cancer with range of 3-10cm in diameter. After the administration of the complex materials, we evaluated the therapeutic effect as well as complication by the follow-up study that included laboratory examination, radioactivity counting and various imaging modalities. 1) In animal experiment, radioactivity of target liver was ranged between 27-33% of total body one, urine excretion between 0.17-0.24 %. White blood cell and platelet counts start diminishing within 7 days and at maximum within 4 weeks after administration of complex materials. In tissue changes of target liver was revealed no significant change in the tumor dose of Ho-166, but periportal fibrosis and massive tissue necrosis in the high ones. 2) In clinical study, total necrosis of tumor is 66%, partial 10% and non-response 24% among 50 patients' liver cancer. The most important complication were leukopenia and thrombocytopenia (82%), the remained was abdominal pain(34%), skin reaction(12%), bile duct obstruction(10%), liver abscess(6%) etc. Conclusively intraarterial injection of Ho-166 CHICO was effective in the treatment of larger and progressed liver cancer. 19 refs., 14 figs., 8 tabs. (Author)

Synthesis and electrical characterization of BaZr0.9Ho0.1O3-δ electrolyte ceramic for IT - SOFCs

Science.gov (United States)

Saini, Deepash S.; Singh, Lalit K.; Bhattacharya, D.

2018-04-01

A cost-effective modified combustion method using citric acid and glycine has recently been developed to synthesize high quality, and nanosized BaZr0.9Ho0.1O3 ceramic powder. BaZr0.9Ho0.1O3-δ ceramic powder was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). XRD pattern of BaZr0.9Ho0.1O3-δ ceramic sintered at 1600 °C has shown that pure phase of BaZr0.9Ho0.1O3-δ with cubic Pm3¯m space group symmetry. The transmission electron microscopic investigation has shown that the particle size of the powder calcined at 1100 °C was in the range 30-80 nm. The FESEM image of sintered pellet at 1600 °C for 4 h reveals porous nature of BaZr0.9Ho0.1O3-δ with 83.7 relative density. Impedance analysis reveal three type relaxations in the temperature range 250 °C to 500 °C as studied at different frequencies over 100 Hz to 1 MHz in air. The grain boundary conductivity of BaZr0.9Ho0.1O3-δ ceramic is found lower then grain (bulk) conductivity due to core-space charge layer behavior in grain boundary.

Towards diode-pumped mid-infrared praseodymium-ytterbium-doped fluoride fiber lasers

Science.gov (United States)

Woodward, R. I.; Hudson, D. D.; Jackson, S. D.

2018-02-01

We explore the potential of a new mid-infrared laser transition in praseodymium-doped fluoride fiber for emission around 3.4 μm, which can be conveniently pumped by 0.975 μm diodes via ytterbium sensitizer co-doping. Optimal cavity designs are determined through spectroscopic measurements and numerical modeling, suggesting that practical diode-pumped watt-level mid-infrared fiber sources beyond 3 μm could be achieved.

Infrared to near-infrared and visible upconversion mechanisms in LiYF 4: Yb3+, Ho3+

NARCIS (Netherlands)

Martín-Rodríguez, R.; Meijerink, A.|info:eu-repo/dai/nl/075044986

2014-01-01

Upconversion materials have regained interest in recent years due to their potential to enhance the efficiency of solar cells. The research has focused on lanthanide based upconverters, especially Er3+- and Yb 3+-doped materials. In this paper we report Ho3+ and Yb3+ upconversion after excitation

Fluoride release and recharge abilities of contemporary fluoride-containing restorative materials and dental adhesives.

Science.gov (United States)

Dionysopoulos, Dimitrios; Koliniotou-Koumpia, Eugenia; Helvatzoglou-Antoniades, Maria; Kotsanos, Nikolaos

2013-01-01

The aim of this study was to evaluate the fluoride release of five fluoride-releasing restorative materials and three dental adhesives, before and after NaF solution treatment. Five restorative materials (Fuji IX GP, GC Corp.; Ketac N100, 3M ESPE; Dyract Extra, Dentsply; Beautifil II, Shofu Inc.; Wave, SDI) and three dental adhesives (Stae, SDI; Fluorobond II - Shofu Inc.; Prime & Bond NT, Dentsply) were investigated before and after NaF solution treatment. A fluoride ion-selective electrode was to measure fluoride concentrations. During the 86-day period before NaF solution treatment, Fuji IX GP released the highest amount of fluoride among the restorative materials while Prime & Bond NT was the highest among the dental adhesives. After NaF solution treatment, Fuji IX GP again ranked the highest in fluoride release among the restorative materials while Fluorobond II ranked the highest among dental adhesives. It was concluded that the compositions and setting mechanisms of fluoride-containing dental materials influenced their fluoride release and recharge abilities.

Valence band electronic structure of Ho-doped La0.67Ca0.33MnO3 using ultra-violet photoemission spectroscopy

Science.gov (United States)

Rout, S. K.; Mukharjee, R. N.; Mishra, D. K.; Roul, B. K.; Sekhar, B. R.; Dalai, M. K.

2017-05-01

In this manuscript we report the valence band electronic structure of Ho doped La0.67Ca0.33MnO3 using ultraviolet photoemission spectroscopy. We compared the density of states of La0.67Ca0.33MnO3, La0.67Ca0.3Ho0.03MnO3 and La0.64Ho0.03Ca0.33MnO3 near the Fermi level at various temperatures. Significant amount of changes have been observed at higher temperatures (220 K and 300 K) where the near Fermi level density of states increases with Ho doping into La0.67Ca0.33MnO3 indicating the enhancement of magnitude of change in metallicity (conductivity).

Ho3+-doped AlF3-TeO2-based glass fibers for 2.1 µm laser applications

Science.gov (United States)

Wang, S. B.; Jia, Z. X.; Yao, C. F.; Ohishi, Y.; Qin, G. S.; Qin, W. P.

2017-05-01

Ho3+-doped AlF3-TeO2-based glass fibers based on AlF3-BaF2-CaF2-YF3-SrF2-MgF2-TeO2 glasses are fabricated by using a rod-in-tube method. The glass rod including a core and a thick cladding layer is prepared by using a suction method, where the thick cladding layer is used to protect the core from the effect of surface crystallization during the fiber drawing. By inserting the glass rod into a glass tube, the glass fibers with relatively low loss (~2.3 dB m-1 @ 1560 nm) are prepared. By using a 38 cm long Ho3+-doped AlF3-TeO2-based glass fiber as the gain medium and a 1965 nm fiber laser as the pump source, 2065 nm lasing is obtained for a threshold pump power of ~220 mW. With further increasing the pump power to ~325 mW, the unsaturated output power of the 2065 nm laser is about 82 mW and the corresponding slope efficiency is up to 68.8%. The effects of the gain fiber length on the lasing threshold, the slope efficiency, and the operating wavelength are also investigated. Our experimental results show that Ho3+-doped AlF3-TeO2-based glass fibers are promising gain media for 2.1 µm laser applications.

Application of fluorides as reagents in exothermal reducing processes

International Nuclear Information System (INIS)

Solov'ev, A.I.; Maksimov, Yu.M.; Dedov, N.V.; Malyutina, V.M.; Avramchik, A.N.

2002-01-01

Thermodynamic calculations were made and the process of calcium-thermic reduction of titanium and zirconium tetrafluorides and their mixtures was experimentally studied. Compound TiF 4 and its mixture with ZrF 4 in amount no more than 34.3 % are reduced producing a well-formed ingot. When ZrF 4 content is exceeded in the mixture to be reduced as well as during reduction of pure ZrF 4 and the mixture of unseparated rare earth metal fluorides, metal and alloys are produced as embedded particles in solidified slag. Additional heat should be brought to produce qualitative ingot during the reducing process. Qualitative ingots of metal in weight up to 10 kg were produced during calcium-thermic reduction of zirconium and rare earth fluorides with application of high-frequency induction heating [ru

A highly efficient Ho:YAG laser in-band pumped by a linewidth-narrowed Tm:YLF laser

International Nuclear Information System (INIS)

Duan, X M; Yang, C H; Yao, B Q; Wang, Y Z; Zhang, W S

2013-01-01

A highly efficient Tm:YLF-Ho:YAG laser system is presented in this paper. To obtain the narrow linewidth 1908 nm laser output, a volume Bragg grating combined with a Fabry–Perot (FP) etalon were used as wavelength selection devices. The maximum output power of 28.7 W was obtained with a slope efficiency of 42.3% in the Tm:YLF laser. An output wavelength of 1908.1 nm and FWHM linewidth of 60 pm were achieved at the maximum output level. Using this Tm:YLF laser as the pump source, high efficiency continuous wave and Q-switched operation of a Ho:YAG laser was demonstrated. Operating at continuous wave mode, up to 73.3% slope efficiency and 67.4% optical conversion efficiency were obtained in the Ho:YAG laser, corresponding to a diode-to-Ho optical conversion efficiency of 23.7%. For the Q-switched mode, when the incident Tm power was 27.3 W, the maximum single pulse energy of 3.4 mJ, pulse width of 15 ns and peak power of 229.3 kW were achieved at the pulse repetition rate of 5 kHz. The maximum average power of 18.3 W, pulse width of 18 ns and peak power of 103.6 kW were obtained at the pulse repetition rate of 10 kHz. (paper)

Calculated high-pressure structural properties, lattice dynamics and quasi particle band structures of perovskite fluorides KZnF3, CsCaF3 and BaLiF3.

Science.gov (United States)

Vaitheeswaran, G; Kanchana, V; Zhang, Xinxin; Ma, Yanming; Svane, A; Christensen, N E

2016-08-10

A detailed study of the high-pressure structural properties, lattice dynamics and band structures of perovskite structured fluorides KZnF3, CsCaF3 and BaLiF3 has been carried out by means of density functional theory. The calculated structural properties including elastic constants and equation of state agree well with available experimental information. The phonon dispersion curves are in good agreement with available experimental inelastic neutron scattering data. The electronic structures of these fluorides have been calculated using the quasi particle self-consistent [Formula: see text] approximation. The [Formula: see text] calculations reveal that all the fluorides studied are wide band gap insulators, and the band gaps are significantly larger than those obtained by the standard local density approximation, thus emphasizing the importance of quasi particle corrections in perovskite fluorides.

New transition metal oxide fluorides with ReO{sub 3}-type structure

Energy Technology Data Exchange (ETDEWEB)

Nakhal, Suliman; Lerch, Martin [Technische Universitaet Berlin (Germany). Inst. fuer Chemie

2016-08-01

The new niobium oxide fluorides MNbO{sub 2}F{sub 4} [M = (Cr, Fe)], CrNb{sub 2}O{sub 4}F{sub 5}, and Fe{sub 2}Nb{sub 3}O{sub 6}F{sub 9} were prepared by treatment of chromium or iron nitrate with Nb-containing hydrofluoric acid solutions. Crystal structures were investigated by means of X-ray powder diffraction. All new compounds can be structurally refined in the cubic ReO{sub 3}-type. The iron niobium oxide fluorides are reddish orange, and chromium containing phases exhibit a light green color. The niobium atoms are in the highest formal oxidation state.

Tunable band gap in epitaxial ferroelectric Ho(Mn,Ga)O{sub 3} films

Energy Technology Data Exchange (ETDEWEB)

Lee, Daesu; Noh, Tae Won, E-mail: twnoh@snu.ac.kr [Center for Correlated Electron Systems, Institute for Basic Science, Seoul 151-742 (Korea, Republic of); Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Choi, Woo Seok [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2016-05-09

Ferroelectrics have recently attracted attention as a new class of materials for use in optical and photovoltaic devices. We studied the electronic properties in epitaxially stabilized ferroelectric hexagonal Ho(Mn{sub 1−x}Ga{sub x})O{sub 3} (x = 0, 0.33, 0.67, and 1) thin films. Our films exhibited systematic changes in electronic structures, such as bandgap and optical transitions, according to the Ga concentration. In particular, the bandgap increased systematically from 1.4 to 3.2 eV, including the visible light region, with increasing Ga concentration from x = 0 to 1. These systematic changes, attributed to lattice parameter variations in epitaxial Ho(Mn{sub 1−x}Ga{sub x})O{sub 3} films, should prove useful for the design of optoelectronic devices based on ferroelectrics.

Electric-field gradients at 181Ta impurity sites in Ho2O3 and Eu2O3 bixbyites

International Nuclear Information System (INIS)

Errico, Leonardo A.; Renteria, Mario; Bibiloni, Anibal G.; Freitag, Kristian

2007-01-01

The time-differential γ-γ perturbed-angular-correlation (PAC) technique with ion-implanted 181 Hf tracers has been applied to study the hyperfine interactions of 181 Ta impurities in the cubic bixbyite structure of Ho 2 O 3 and Eu 2 O 3 . The PAC experiments were performed in air in the temperature range 300-1373 K (in the case of Ho 2 O 3 ) and 77-1273 K (in the case of Eu 2 O 3 ). For both oxides, two electric-quadrupole interactions were found and attributed to the electric-field gradients (EFGs) acting on 181 Ta probes substitutionally located at the two free-of-defects nonequivalent cation sites of the bixbyite structure. In the case of Ho 2 O 3 , two additional interactions were found in the temperature range 300-573 K. These results, as well as previous characterizations of the EFG at 181 Ta sites in bixbyites, were compared to those obtained in experiments using 111 Cd as probe, and to point-charge model calculations. Very recent ab initio predictions for the EFG tensor at impurities sites in binary oxides are also discussed. All these results enable us to discuss the validity of the widely used ionic model to describe the EFG in these highly ionic compounds

In vitro evaluation of fluoride products in the development of carious lesions in deciduous teeth

Directory of Open Access Journals (Sweden)

Lucineide de Melo Santos

2009-09-01

Full Text Available The purpose of this study was to evaluate the effect of the application of fluoride products on the development of enamel caries in deciduous teeth. A total of 108 deciduous teeth were chosen for the study. Acid-resistant varnish was applied on the teeth, leaving only one area of 5 mm x 1 mm of dental enamel exposed. The teeth were allocated randomly to one of the following groups: 1 control - toothpaste without fluoride; 2 1.23% fluoride gel; 3 Duraflur fluoride varnish; 4 Duraphat fluoride varnish; 5 Fluorniz fluoride varnish; 6 Fluorphat fluoride varnish; 7 varnish with Duofluorid; 8 12% silver fluoride diamine (Cariestop; 9 children's fluoride toothpaste (500 ppm. The tested products were applied on the teeth according to the manufacturer's recommendations and the teeth were stored in a moist environment for 24 hours. Each group of teeth was then subjected to a pH cycling model for 14 days, after which the teeth were cut through the center for an analysis of the depth of the carious lesion by polarized light microscopy. Comparisons were made between the treatments and the control group. The mean lesion depth values were 318 μm ± 39 (control, 213 μm ± 27 (fluoride gel, 203 μm ± 34 (Duraflur, 133 μm ± 25 (Duraphat, 207 μm ± 27 (Fluor-niz, 212 μm ± 27 (Fluorphat, 210 ± 28 (Duofluorid, 146 ± 31 (Cariestop and 228 ± 24 (fluoride toothpaste. None of the products used here was able to completely prevent the formation of lesions. The highest cariostatic effect was achieved by fluoride varnish Duraphat and the lowest by the fluoride toothpaste.

Purification process of uranium hexafluoride containing traces of plutonium fluoride and/or neptunium fluoride

International Nuclear Information System (INIS)

Aubert, J.; Bethuel, L.; Carles, M.

1983-01-01

In this process impure uranium hexafluoride is contacted with a metallic fluoride chosen in the group containing lead fluoride PbF 2 , uranium fluorides UFsub(4+x) (0 3 at a temperature such as plutonium and/or neptunium are reduced and pure uranium hexafluoride is recovered. Application is made to uranium hexafluoride purification in spent fuel reprocessing [fr

Ho3+-Yb3+ codoped tellurite based glasses in visible lasers and optical devices: Judd-Ofelt analysis and frequency upconversion

Science.gov (United States)

Azam, Mohd; Rai, Vineet Kumar

2017-04-01

The optical absorption and frequency upconversion emission in the Ho3+/Yb3+ codoped TeO2-ZnO (TZ), TeO2-ZnO-WO3 (TZW) and TeO2-ZnO-WO3-TiO2 (TZWTi) glasses prepared by melting and quenching method has been studied. Judd-Ofelt theory has been used to calculate the Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6), transition probabilities, radiative lifetimes, absorption cross sections and the branching ratios. Upconversion (UC) emission bands centered at ∼ 549 nm, ∼658 nm and ∼754 nm are observed upon 980 nm excitation. On codoping with the Yb3+ ions at 3.0 mol% the upconversion emission intensity enhancement of about ∼57 times, ∼342 times and ∼480 times for the green band whereas for the red band arising from the Ho3+ ions it is about ∼71 times, ∼438 times and ∼707 times respectively have been observed. The enhancement observed in the UC emission intensity is explained on the basis of efficient energy transfer from Yb3+ to Ho3+, larger absorption cross section, larger oscillator strengths and increase in the local field corrections factor. The spectroscopic quality factor Ω4/Ω6 has been calculated to get the information about the developed materials for laser applications. The upconversion emission cross section determined on the basis of Judd-Ofelt analysis is found to be maximum for Ho-Yb-TZWTi glass. The nephelauxetic ratio, bonding and covalency parameters have been calculated to know the nature of bonding between the rare earth ions and neighbouring oxygen atoms. The high color purity 83.8% has been reported in the codoped glasses at ∼81.2 W/cm2 pump power density.

Self-propagating high temperature synthesis, structural morphology and magnetic interactions in rare earth Ho{sup 3+} doped CoFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Lohar, K.S. [Materials Research Laboratory, Srikrishna Mahavidyalaya Gunjoti, Omerga, Osmanabad 413 613, MS (India); Pachpinde, A.M.; Langade, M.M. [Department of Chemistry, Jawahar Art Science and Commerce College Andur, Osmanabad, MS (India); Kadam, R.H. [Materials Research Laboratory, Srikrishna Mahavidyalaya Gunjoti, Omerga, Osmanabad 413 613, MS (India); Shirsath, Sagar E., E-mail: shirsathsagar@hotmail.com [Spin Device Technology Center, Department of Information Engineering, Shinshu University, Nagano 380-8553 (Japan)

2014-08-01

Highlights: • Rare earth Ho{sup 3+} substituted CoFe{sub 2}O{sub 4.} • XRD and IR spectra reveal the spinel structure. • Magnetization and coercivity increased with Ho{sup 3+} substitution. - Abstract: Substitution effect of rare earth trivalent Ho{sup 3+} ions on the composition, Ho{sub x}CoFe{sub 2−x}O{sub 4}, with x varying from 0.0 to 0.1 in steps of 0.025 using sol–gel auto combustion route has been investigated. Examination of X-ray diffraction (XRD) patterns shows that all the samples consisted of ferrite phases of typical spinel cubic structure, and when Ho{sup 3+} ion content was x ⩾ 0.075, orthoferrite–HoFeO{sub 3} phase was detected. The micro and nanostructure of the synthesized Ho doped CoFe{sub 2}O{sub 4} ferrites were investigated by scanning and transmission electron microscopy respectively. With increasing doping content of Ho{sup 3+} ions, the lattice constant, particle size and bulk density increased, and after an increase to its maximum value, the sample particle size and density dropped down. Cation distribution estimated from XRD patter revealed that the Co{sup 2+} and Ho{sup 3+} ions prefer to occupy octahedral B-site whereas Fe{sup 3+} ions are distributed over tetra- and octa-hedral site. Oxygen positional parameter shows larger values than its ideal value. The analysis of magnetic properties revealed that the saturation magnetization and coercivity of CoFe{sub 2}O{sub 4} increased with the rare earth Ho{sup 3+} substitution.

Magnetic properties of lithium rare-earth fluorides: Ferromagnetism in LiErF4 and LiHoF4 and crystal-field parameters at the rare-earth and Li sites

DEFF Research Database (Denmark)

Hansen, P. E.; Johansson, Torben; Nevald, Rolf

1975-01-01

Single crystals of LiErF4 and LiHoF4 have been grown and their magnetic properties measured from 1.3 K to 300 K. LiHoF4 turned out to be a nearly ideal Ising ferromagnet with TC=1.30±0.05 K and a saturation magnetization along the crystalline c axis of (6.98±0.02)μB. In LiErF4 no ordering...... was observed, but extrapolation indicates that below 0.5 K it will be ferromagnetic with the magnetic moments in the crytalline ab plane. From the susceptibilities the crystal-field parameters Bnm with (n, m)=(2, 0), (4, 0), (4, 4), (6, 0), (6, 4) have been extracted giving for Er3+ in LiErF4: 430., -985......., 1185., -5., 740.+i135. (cm-1) and for Ho3+ in LiHoF4: 470., -825., 1050., -10., 760.+i150 (cm-1). The exchange constants were found to be small compared to the dipole interactions. Furthermore the 7Li NMR spectra have been obtained in these materials as well as in LiTbF4 thereby determining the second...

Fluoridated Water

Science.gov (United States)

... Genetics Services Directory Cancer Prevention Overview Research Fluoridated Water On This Page What is fluoride, and where is it found? What is water fluoridation? When did water fluoridation begin in the ...

CsSc{sub 3}F{sub 6}[SeO{sub 3}]{sub 2}. A new rare-earth metal(III) fluoride oxoselenate(IV) with sections of the ReO{sub 3}-type structure

Energy Technology Data Exchange (ETDEWEB)

Greiner, Stefan; Schleid, Thomas [Institut fuer Anorganische Chemie, Universitaet Stuttgart (Germany)

2017-09-04

A new representative of rare-earth metal(III) fluoride oxoselenates(IV) derivatized with alkali metals could be synthesized via solid-state reactions. Colorless single crystals of CsSc{sub 3}F{sub 6}[SeO{sub 3}]{sub 2} were obtained through the reaction of Sc{sub 2}O{sub 3}, ScF{sub 3}, and SeO{sub 2} (molar ratio 1:1:3) with CsBr as reactant and fluxing agent. For this purpose, corundum crucibles embedded as liners into evacuated silica ampoules were applied as containers for these reactions at 700 C for seven days. The new quintenary compound crystallizes in the trigonal space group P3m1 with a = 565.34(4) and c = 1069.87(8) pm (c/a = 1.892) for Z = 1. The crystal structure of CsSc{sub 3}F{sub 6}[SeO{sub 3}]{sub 2} contains two crystallographically different Sc{sup 3+} cations. Each (Sc1){sup 3+} is surrounded by six fluoride anions as octahedron, while the octahedra about (Sc2){sup 3+} are formed by three fluoride anions and three oxygen atoms from three terminal [SeO{sub 3}]{sup 2-} anions. The [(Sc1)F{sub 6}]{sup 3-} octahedra link via common F{sup -} vertices to six fac-[(Sc2)F{sub 3}O{sub 3}]{sup 6-} octahedra forming {sup 2}{sub ∞}{[Sc_3F_6O_6]"9"-} layers parallel to (001). These layers are separated by oxygen-coordinated Cs{sup +} cations (C.N. = 12), arranging for the charge compensation, while Se{sup 4+} cations within the layers surrounded by three oxygen atoms as ψ{sup 1}-tetrahedral [SeO{sub 3}]{sup 2-} units complete the structure. EDX measurements confirmed the composition of the title compound and single-crystal Raman studies showed the typical vibrational modes of isolated [SeO{sub 3}]{sup 2-} anions with ideal C{sub 3v} symmetry. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

3D nuclear organization of telomeres in the Hodgkin cell lines U-HO1 and U-HO1-PTPN1: PTPN1 expression prevents the formation of very short telomeres including "t-stumps"

Directory of Open Access Journals (Sweden)

Lemieux Bruno

2010-12-01

Full Text Available Abstract Background In cancer cells the three-dimensional (3D telomere organization of interphase nuclei into a telomeric disk is heavily distorted and aggregates are found. In Hodgkin's lymphoma quantitative FISH (3D Q-FISH reveals a major impact of nuclear telomere dynamics during the transition form mononuclear Hodgkin (H to diagnostic multinuclear Reed-Sternberg (RS cells. In vitro and in vivo formation of RS-cells is associated with the increase of very short telomeres including "t-stumps", telomere loss, telomeric aggregate formation and the generation of "ghost nuclei". Results Here we analyze the 3D telomere dynamics by Q-FISH in the novel Hodgkin cell line U-HO1 and its non-receptor protein-tyrosine phosphatase N1 (PTPN1 stable transfectant U-HO1-PTPN1, derived from a primary refractory Hodgkin's lymphoma. Both cell lines show equally high telomerase activity but U-HO1-PTPN differs from U-HO1 by a three times longer doubling time, low STAT5A expression, accumulation of RS-cells (p As expected, multinuclear U-HO1-RS-cells and multinuclear U-HO1-PTPN1-RS-cells differ from their mononuclear H-precursors by their nuclear volume (p Conclusion Abundant RS-cells without additional very short telomeres including "t-stumps", high rate of apoptosis, but low STAT5A expression, are hallmarks of the U-HO1-PTPN1 cell line. These characteristics are independent of telomerase activity. Thus, PTPN1 induced dephosphorylation of STAT5 with consecutive lack of Akt/PKB activation and cellular arrest in G2, promoting induction of apoptosis, appears as a possible pathogenetic mechanism deserving further experimental investigation.

Violet and visible up-conversion emission in Yb{sup 3+}-Ho{sup 3+} co-doped germanium-borate glasses

Energy Technology Data Exchange (ETDEWEB)

Yang Yanmin, E-mail: mihuyym@163.co [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Zhang Meixin [Forensic Science Lab, Hebei University, Baoding 071002 (China); Yang Zhiping [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Fu Zuoling [Key Laboratory of Coherent Light, Atomic and Molecular Spectroscopy, College of physics, Jilin University, Ministry of Education, Changchun 130023 (China)

2010-10-15

The up-conversion emission properties of Yb{sup 3+}-Ho{sup 3+} co-doped germanium-borate glasses have been investigated with 980 nm excitation. The violet, blue, green and red emission bands at about 350, 485, 544 and 653 nm can be identified, respectively. Experimental results indicated that the relative intensity ratios of the peaks I{sub Red}/I{sub Green} increased with increasing B{sub 2}O{sub 3} concentration, which led to changing color of up-conversion emission from green at x=0 to yellow at x=40, to red at x=60. The violet emission at 350 nm was first reported in germanium-borate glass host and up-conversion mechanisms of the emissions were discussed. The Yb{sup 3+}-Ho{sup 3+} co-doped germanium-borate glasses could be an alternative for the generation of violet and primary colors for application in solid-state displays.

Fluoride retention by kaolin clay

DEFF Research Database (Denmark)

Kau, P. M. H.; Smith, D. W.; Binning, Philip John

1997-01-01

To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p......H and available fluoride concentration with equilibrium being achieved within 24 h. A site activation process involving the uptake of fluoride was also observed at the initial stages of sorption. This behaviour was attributed to a layer expansion process of the clay during sorption. The maximum fluoride sorption...... capacity was found to be 18.3 meq/100 g at pH 6 and 8.6 meq/100 g at pH 7. A competitive Langmuir sorption isotherm where sorption is dependant on both pH and fluoride concentration is employed to characterise the experimental sorption and desorption data. The sorption and desorption isotherms revealed...

Preparation and Quality Control of 166Ho Labelled Polylactic Acid Microspheres for radiotherapy

Czech Academy of Sciences Publication Activity Database

Kropáček, Martin; Melichar, František; Klejzarová, Michaela; Ventruba, Jiří; Tomeš, Marek; Mirzajevová, Marcela

2007-01-01

Roč. 2, č. 332 (2007), s. 34-34 ISSN 1619-7070 R&D Projects: GA AV ČR 1QS100480501 Institutional research plan: CEZ:AV0Z10480505 Keywords : polylactic acid microspheres * 166Ho * liver tumour therapy Subject RIV: FR - Pharmacology ; Medidal Chemistry

Tunable multicolor and enhanced red emission of monodisperse CaF2:Yb3+/Ho3+ microspheres via Mn2+ doping

Science.gov (United States)

Wang, Rui; Yuan, Maohui; Zhang, Chaofan; Wang, Hongyan; Xu, Xiaojun

2018-05-01

Transition metal ions (e.g. Mn2+) and lanthanide co-doped upconversion (UC) materials have attracted wide attention in recent years due to their promising application in multicolor display. Here, we report the hydrothermal synthesis and characterization of Mn2+ doped monodisperse CaF2:Yb3+/Ho3+ microspheres. The results of X-ray diffraction (XRD) revealed that Mn2+ doping does not change the cubic phase of CaF2 material but will lead to diffraction peaks shifting slightly towards higher angle due to the substitution of larger Ca2+ by the relatively smaller Mn2+. Under the excitation of 980 nm continuous wave (CW) laser, these microspheres exhibit green-yellow-red tuning colors and remarkable enhancement of both red to green ratio (R/G) and red to blue ratio (R/B) when increasing Mn2+ concentration from 0 to 30 mol%. The energy migration process between Ho3+ and Mn2+ was proposed and supported by time-decay and power dependence measurements of Ho3+ UC emission. These upconversion materials may have potential applications in optical devices, color display, nanoscale lasers and biomedical imaging.

Effective tuning of the ratio of red to green emission of Ho{sup 3+} ions in single LiLuF{sub 4} microparticle via codoping Ce{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Gao, Wei, E-mail: gaowei@xupt.edu.cn; Dong, Jun; Liu, Jihong; Yan, Xuewen

2016-09-15

Yb{sup 3+}/Ho{sup 3+} codoped LiLuF{sub 4} microparticles have been successfully prepared via a facile hydrothermal method. The crystal phase and morphology of LiLuF{sub 4} microparticles were inspected by x-ray diffraction and scanning electron microscope, respectively. The upconversion emission of single LiLuF{sub 4}: Yb{sup 3+}/Ho{sup 3+} microparticle was carefully studied by a confocal microscopy setup under NIR 980 nm excitation. With the increase of Ce{sup 3+} ion concentrations of 12%, the ratio of red to green emission of the Ho{sup 3+} ions of single LiLuF{sub 4} microparticle was boosted about 17-fold, and the output colors were tuned from green to red, which is due to the two efficient cross-relaxation between Ho{sup 3+} and Ce{sup 3+} ions enhances the red and suppresses the green in the emission processes. To investigate the optical properties of the single microparticle or nanoparticle through the confocal microscopy setup can effectively avoid the influence of surrounding particle or environment, and could provide more precise information for better exploring the emission mechanisms of rare earth ions. The tunable upconversion emission of Ho{sup 3+} in single LiLuF{sub 4} microparticle in this work will have great potential applications in the micro optoelectronic devices and color display applications. - Highlights: • The optical properties of the single LiLuF4: Yb3+/Ho3+/Ce3+ microparticle were studied. • The output colors of single LiLuF4 microparticle were tuned from green to red. • The upconversion mechanisms between Ho3+ and Ce3+ ions were discussed based on emission spectrum.

Fluoride adsorption from aqueous solution by magnetic core-shell Fe_3O_4@alginate-La particles fabricated via electro-coextrusion

International Nuclear Information System (INIS)

Zhang, Yahui; Lin, Xiaoyan; Zhou, Quisheng; Luo, Xuegang

2016-01-01

Graphical abstract: The magnetic core-shell Fe_3O_4@Alg-La particles were fabricated successfully by a simple method of electro-coextrusion, and employed as an adsorbent for separation of fluoride from aqueous solution. - Highlights: • Magnetic core-shell Fe_3O_4@Alg-La particles were prepared by electro-coextrusion. • The maximum adsorption capacity for fluoride at 298.15 K was 45.230 mg/g. • The adsorbent has a good saturation magnetization value. • The adsorbent has a great potential in removing the fluoride. - Abstract: The magnetic core-shell Fe_3O_4@Alg-La particles were fabricated successfully by a simple method of electro-coextrusion, and employed as an adsorbent for separation of fluoride from aqueous solution. Main factors affecting the removal of fluoride, including pH, adsorbent dosage, initial concentration, temperature and contact time were investigated. The adsorption isotherm and adsorption kinetics were studied to understand the adsorption process in detail. The experimental data were fitted well by the non-linear Freundlich isotherm and linear pseudo-second-order model, the maximum fluoride adsorption capacity was 45.230 mg/g at pH 4, 298.15 K. Thermodynamic parameters indicated that the fluoride adsorption process was feasible and spontaneous. The presence of other anions like Cl"−, SO_4"2"−, HCO_3"− and PO_4"3"− had almost no effect on the fluoride adsorption. The adsorbent can be easily separated from the solution by a magnet. The magnetic core-shell Fe_3O_4@Alg-La particles before and after fluoride adsorption were studied by SEM, FTIR, EDX and XPS, which indicated that the adsorption mechanism may be related to electrostatic attraction and Lewis acid-base interaction.

Daily Fluoride Intake from Iranian Green Tea: Evaluation of Various Flavorings on Fluoride Release

Directory of Open Access Journals (Sweden)

Afshin Maleki

2016-01-01

Full Text Available With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan. The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea and 3.29 mg/L (bagged peach-flavored green tea, respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas ( P 0.05. Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers.

Magnetic properties and magnetocaloric effect of HoCo3B2 compound

Science.gov (United States)

Zheng, X. Q.; Xu, J. W.; Zhang, H.; Zhang, J. Y.; Wang, S. G.; Zhang, Y.; Xu, Z. Y.; Wang, L. C.; Shen, B. G.

2018-05-01

A sample of HoCo3B2 compound was synthesized, and the magnetic and MCE properties were investigated. Compound shows a change corresponding to R-R (R = rare earth) sublattice magnetic order transition and the transition temperature is determined to be 11.8 K (TC). The characteristic of Arrott plots with positive slope around TC was observed, indicating a second-order phase transition. Based on isothermal magnetization data, together with Maxwell's relationship, the magnetic entropy change (-ΔSM) was calculated. The maximum -ΔSM reaches 7.8, 12.7 and 14.4 J/kg K for field range of 0-2 T, 0-5 T and 0-7 T, respectively. Accordingly, the value of RC (refrigerant capacity) is 99, 289 and 432 J/kg for above field ranges. The large MCE of HoCo3B2 compound indicates its potential application for magnetic refrigeration in low temperature range.

Magnetism of cyano-bridged Ln3+-M3+ complexes. Part II: one-dimensional complexes (Ln3+ = Eu, Tb, Dy, Ho, Er, Tm; M3+ = Fe or Co) with bpy as blocking ligand.

Science.gov (United States)

Figuerola, Albert; Ribas, Joan; Casanova, David; Maestro, Miguel; Alvarez, Santiago; Diaz, Carmen

2005-10-03

The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to 13 one-dimensional complexes: trans-[M(CN)4(mu-CN)2Ln(H2O)4(bpy)]n.4nH2O.1.5nbpy (Ln = Eu3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Lu3+; M = Fe3+, Co3+). The structures for [EuFe]n (1), [TbFe]n (2), [DyFe]n (3), [HoFe]n (4), [ErFe]n (5), [TmFe]n (6), [LuFe]n (7), [EuCo]n (8), [TbCo]n (9), [DyCo]n (10), [HoCo]n (11), [ErCo]n (12), and [TmCo]n (13) have been solved: they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular architecture created by the interplay of coordinative, hydrogen bonding, and pi-pi interactions. A stereochemical study of the eight-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. The Ln3+-Fe3+ interaction is antiferromagnetic in [DyFe]n and [TbFe]n. For [EuFe]n, [HoFe]n, [ErFe]n, and [TmFe]n, there is no sign of any significant interaction. The magnetic behavior of [DyFe]n suggests the onset of weak long-range ferromagnetic ordering at 2.5 K.

Investigation of Chemical Durability Mechanisms and Structure of Fluoride Glasses.

Science.gov (United States)

1988-03-01

Compositions of fluorozirconate glasses (mol%) mnemonic ZrF 4 BaF 2 LaF 3 A1F 3 LiF source ZBLA 57 36 3 4 -- RADC* ZBLA-F 51.16 38.62 5.66 4.56 -- Le Verre ...Fluore4 ZBLAL 51.8 20.0 5.3 3.3 19.6 NRL * Rome Air Development Center, Hanscom AFB, MA (Dr. El Bayoumi) # Le Verre Fluore’ Co., LeMans, France &#34 Naval...Maine, LeMans, France, (with partial support from the French Foreign Office), studied corrosion of UF4 -based fluorides. - Michel Le Toullec - 10/86

Energy transfer between doubly doped Er3+, Tm3+and Ho3+ rare earth ions in SiO2 nanoparticles

CSIR Research Space (South Africa)

Dhlamini, MS

2011-04-01

Full Text Available + and Ho3+ ions are reported. Another emission peak in the near infra-red (NIR) region at 875 nm from Er3+ was also measured. Blue emission at 460 nm, red at 705 nm and a NIR peak in the region of 865 nmfrom Tm3+ were observed. Red, green and blue (RGB...

Controllable synthesis of Eu{sup 3+}/Tb{sup 3+} activated lutetium fluorides nanocrystals and their photophysical properties

Energy Technology Data Exchange (ETDEWEB)

Lin, Jintai; Huo, Jiansheng [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Cai, Yuepeng [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Wang, Qianming, E-mail: qmwang@scnu.edu.cn [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China)

2013-12-15

In this paper, phosphors of LuF{sub 3}:Eu{sup 3+}/Tb{sup 3+} have been successfully synthesized with small chelator ethylenediaminetetra acetic acid (EDTA) or amphiphilic polymer (polyethylene glycol, PEG-1000) as templates via a hydrothermal method. X-ray powder diffraction (XRD), scanning electronic microscope (SEM), and photo-luminescent spectra techniques (PL) were used to characterize the as-prepared samples. XRD patterns showed that well crystallized lanthanide fluorides with hexagonal phase were achieved. SEM images revealed that different regular microstructures were achieved. The photo-luminescent properties of LuF{sub 3}:Eu{sup 3+} demonstrated that there are significant energy transfers from fluorides to Eu{sup 3+}. The results presented that EDTA as the template will lead to the highest emission intensities. -- Highlights: • Various templates were used to synthesize LuF{sub 3}:Eu{sup 3+}/Tb{sup 3+}. • All the phosphors were red or green emissive. • Different morphologies were acquired and controllable.

Relationship of Heme Oxygenase-1 (HO-1 Level with Onset and Severity in Normotensive Pregnancy and Severe Preeclampsia

Directory of Open Access Journals (Sweden)

John Johannes Wantania

2016-08-01

Full Text Available Background: Preeclampsia still becomes a major problem in pregnancies. Various evidences showed that heme oxygenase-1 (HO-1 is very important in pregnancy. This study aims to understand the relationship of heme oxygenase-1 level with onset and severity in normotensive pregnancy and severe preeclampsia. Methods: This is a cross sectional analytic comparative study, the subjects consisted of 26 patients with normotensive pregnancies and 26 patients with severe preeclampsia. Blood samples from women with < 34 / ≥ 34 weeks’ normotensive pregnancies and women with severe preeclampsia were taken. HO-1 ELISA kit used to quantitate heme oxygenase-1 level in samples. Results: The level of heme oxygenase-1 in normotensive pregnant women < 34 weeks lower than severe preeclampsia pregnant women < 34 weeks (3.28 ± 0.46 ng/mL vs 4.20 ± 0.64 ng/mL, p=0.003, respectively. The median level of heme oxygenase-1 in normotensive pregnant women ≥ 34 weeks was 2.96 (2.41–4.39 ng/mL, while severe preeclampsia pregnant women ≥ 34 weeks was 3.52 (2.88–5.43 ng/mL, (p=0.040. The median level of heme oxygenase-1 in normotensive pregnant women was 3.04 (2.41–4.39 ng/mL, while severe preeclampsia pregnant women was 3.68 (2.88–5.67 ng/mL, (p=0.001. Conclusions: There is correlation between the incidence of severe preeclampsia with heme oxygenase-1 level in < 34 and ≥ 34 weeks of pregnancy. There is a significant difference between the level of heme oxygenase-1 in pregnant women with severe preeclampsia and in women with normotensive pregnancy. 

Factors influencing the removal of fluoride from aqueous solution by calcined Mg-Al-CO{sub 3} layered double hydroxides

Energy Technology Data Exchange (ETDEWEB)

Lv Liang [Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Box 98, 15 Bei San Huan Dong Lu, Chao Yang District, Beijing 100029 (China); West Branch of Zhejiang University of Technology, Zhejiang 324006 (China); He Jing [Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Box 98, 15 Bei San Huan Dong Lu, Chao Yang District, Beijing 100029 (China); Wei Min [Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Box 98, 15 Bei San Huan Dong Lu, Chao Yang District, Beijing 100029 (China); Evans, D.G. [Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Box 98, 15 Bei San Huan Dong Lu, Chao Yang District, Beijing 100029 (China); Duan Xue [Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Box 98, 15 Bei San Huan Dong Lu, Chao Yang District, Beijing 100029 (China)]. E-mail: duanx@mail.buct.edu.cn

2006-05-20

Layered double hydroxides (LDH) calcined at different temperatures (denoted as CLDH) have been demonstrated to recover their original layered structure in the presence of appropriate anions. In the light of this so-called 'memory effect', a study of removal of fluoride from aqueous solution by calcined Mg-Al-CO{sub 3}-LDH has been carried out. The LDH calcined at 500 deg. C had the highest capacity of removal of fluoride ion, because of retention of its intrinsic structure. The CLDH with an Mg/Al ratio of 2 has a remarkable ability to adsorb anions. The adsorption loading is higher for the calcined Mg-Al-LDH than for calcined Zn-Al and Ni-Al-LDH. The influence of varying the conditions for removal of fluoride, such as the pH of aqueous solution, the initial fluoride concentration, the dosage of adsorbent, and temperature on removal of fluoride have been investigated. The influence of co-existing anions in fluoride aqueous solution indicates that the percentage of removal of fluoride increased in order PO{sub 4} {sup 3-} < Cl{sup -} {approx} SO{sub 4} {sup 2-} < Br{sup -} << NO{sub 3} {sup -}. It was found that maximum removal of fluoride from aqueous solutions was obtained in 6 h at pH 6.0 with an initial concentration of 50 mg/L, and that the retention of fluoride ions by the CLDH material was 98% or higher. The residual fluoride concentration was found to be 0.4 mg/L with an initial concentration of 20 mg/L, which meets the national standard for drinking water quality. The Freundlich isotherm and Langmuir isotherm were used to fit the data of equilibrium experiments. The results of X-ray diffraction, FT-IR and TG-MS demonstrate that the adsorption phenomenon is accompanied by rehydration with concomitant uptake of fluoride ions to rebuild the initial layered structure.

Magnetic ordering in Ho-doped Bi{sub 2}Te{sub 3} topological insulator

Energy Technology Data Exchange (ETDEWEB)

Figueroa, A.I.; Van der Laan, G.; Hesjedal, T. [Magnetic Spectroscopy Group, Diamond Light Source, Didcot (United Kingdom); Harrison, S.E. [Department of Physics, Clarendon Laboratory, University of Oxford (United Kingdom); Department of Electrical Engineering, Stanford University, Stanford, CA (United States); Collins-McIntyre, L.J. [Department of Physics, Clarendon Laboratory, University of Oxford (United Kingdom)

2016-06-15

We investigate the magnetic properties of Ho-doped Bi{sub 2}Te{sub 3} thin films grown by molecular beam epitaxy. Analysis of the polarized X-ray absorption spectra at the Ho M{sub 5} absorption edge gives an effective 4f magnetic moment which is ∝45% of the Hund's rule ground state value. X-ray magnetic circular dichroism (XMCD) shows no significant anisotropy, which suggests that the reduced spin moment is not due to the crystal field effects, but rather the presence of non-magnetic or antiferromagnetic Ho sites. Extrapolating the temperature dependence of the XMCD measured in total electron yield and fluorescence yield mode in a field of 7 T gives a Curie-Weiss temperature of and vartheta;{sub CW} ∼ -30 K, which suggests antiferromagnetic ordering, in contrast to the paramagnetic behavior observed with SQUID magnetometry. From the anomaly of the XMCD signal at low temperatures, a Neel temperature T{sub N} between 10 K and 25 K is estimated. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Magnetic properties of two new compounds: Pr2Ni3Si5 and Ho2Ni3Si5

International Nuclear Information System (INIS)

Mazumdar, C.; Padalia, B.D.; Godart, C.

1994-01-01

Formation of two more new materials, Pr 2 Ni 3 Si 5 and Ho 2 Ni 3 Si 5 , of the series, R 2 Ni 3 Si 5 (R = rare earth and Y) and their magnetic properties are reported here. These materials crystallize in the orthorhombic U 2 Co 3 Si 5 -type structure (space group Ibam). Magnetic susceptibility measurement in the temperature range 5 K--300 K show that the compound Pr 2 Ni 3 Si 5 order antiferromagnetically at T N ∼ 8.5 K and Ho 2 Ni 3 Si 5 at ∼ 6 K. Considering T N (Gd 2 Ni 3 Si 5 ) ∼ 15 K, T N (Pr 2 Ni 3 Si 5 ) ∼ 8.5 K is rather high. The magnetic susceptibility of both of the materials, in the paramagnetic state, follows a Curie-Weiss law with effective moment close to that of the corresponding free trivalent rare earth ion

Effect of concentration variation on 2.0 µm emission of Ho3+-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 oxyfluorosilicate glasses

Science.gov (United States)

Gelija, Devarajulu; Borelli, Deva Prasad Raju

2018-02-01

The concentration variation of Ho3+ ion-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 glasses has been prepared by conventional melt quenching method. The thermal stability of 1 mol % of Ho3+-doped oxyfluorosilicate glass has been calculated using the differential thermal analysis (DTA) spectra. The phenomenological Judd-Ofelt intensity parameters Ωλ ( λ = 2, 4 and 6) were calculated for all concentrations of Ho3+ ions. The luminescence spectra in visible region of Ho3+ ion-doped glasses were recorded under the excitation wavelength of 452 nm. The spectra consists of several intense emission bands (5F4, 5S2) → 5I8 (547 nm), 5F3 → 5I8 (647 nm), 5F5 → 5I7 (660 nm) and (5F4, 5S2) → 5I7 (750 nm) in the range 500-780 nm. The fluorescence emission at ˜2.0 µm (5I7 → 5I8) was observed under the excitation of 488 nm Ar-ion laser. The stimulated emission cross section for 5I7 → 5I8 transition (˜2.0 µm) varies from 8.46 to 9.52 × 10-21 cm2, as calculated by the Fuchtbauer-Ladenburg (FL) theory. However, Mc-Cumber theory was used to calculate emission cross section values about 4.24-5.75 × 10-21 cm2 for the 5I7 → 5I8 transition in all concentrations of Ho3+-doped oxyfluorosilicate glasses. Therefore, these results reveal that the 0.5 mol % of Ho3+-doped oxyfluorosilicate glasses, exhibiting higher emission cross section, has potentially been used for laser applications at ˜ 2.0 µm.

Metabolomic Effects of Xylitol and Fluoride on Plaque Biofilm in Vivo

Science.gov (United States)

Takahashi, N.; Washio, J.

2011-01-01

Dental caries is initiated by demineralization of the tooth surface through acid production from sugar by plaque biofilm. Fluoride and xylitol have been used worldwide as caries-preventive reagents, based on in vitro-proven inhibitory mechanisms on bacterial acid production. We attempted to confirm the inhibitory mechanisms of fluoride and xylitol in vivo by performing metabolome analysis on the central carbon metabolism in supragingival plaque using the combination of capillary electrophoresis and a time-of-flight mass spectrometer. Fluoride (225 and 900 ppm F−) inhibited lactate production from 10% glucose by 34% and 46%, respectively, along with the increase in 3-phosphoglycerate and the decrease in phosphoenolpyruvate in the EMP pathway in supragingival plaque. These results confirmed that fluoride inhibited bacterial enolase in the EMP pathway and subsequently repressed acid production in vivo. In contrast, 10% xylitol had no effect on acid production and the metabolome profile in supragingival plaque, although xylitol 5-phosphate was produced. These results suggest that xylitol is not an inhibitor of plaque acid production but rather a non-fermentative sugar alcohol. Metabolome analyses of plaque biofilm can be applied for monitoring the efficacy of dietary components and medicines for plaque biofilm, leading to the development of effective plaque control. PMID:21940519

Metabolomic effects of xylitol and fluoride on plaque biofilm in vivo.

Science.gov (United States)

Takahashi, N; Washio, J

2011-12-01

Dental caries is initiated by demineralization of the tooth surface through acid production from sugar by plaque biofilm. Fluoride and xylitol have been used worldwide as caries-preventive reagents, based on in vitro-proven inhibitory mechanisms on bacterial acid production. We attempted to confirm the inhibitory mechanisms of fluoride and xylitol in vivo by performing metabolome analysis on the central carbon metabolism in supragingival plaque using the combination of capillary electrophoresis and a time-of-flight mass spectrometer. Fluoride (225 and 900 ppm F(-)) inhibited lactate production from 10% glucose by 34% and 46%, respectively, along with the increase in 3-phosphoglycerate and the decrease in phosphoenolpyruvate in the EMP pathway in supragingival plaque. These results confirmed that fluoride inhibited bacterial enolase in the EMP pathway and subsequently repressed acid production in vivo. In contrast, 10% xylitol had no effect on acid production and the metabolome profile in supragingival plaque, although xylitol 5-phosphate was produced. These results suggest that xylitol is not an inhibitor of plaque acid production but rather a non-fermentative sugar alcohol. Metabolome analyses of plaque biofilm can be applied for monitoring the efficacy of dietary components and medicines for plaque biofilm, leading to the development of effective plaque control.

Magnetic properties and magnetocaloric effect of HoCo3B2 compound

Directory of Open Access Journals (Sweden)

X. Q. Zheng

2018-05-01

Full Text Available A sample of HoCo3B2 compound was synthesized, and the magnetic and MCE properties were investigated. Compound shows a change corresponding to R-R (R = rare earth sublattice magnetic order transition and the transition temperature is determined to be 11.8 K (TC. The characteristic of Arrott plots with positive slope around TC was observed, indicating a second-order phase transition. Based on isothermal magnetization data, together with Maxwell’s relationship, the magnetic entropy change (-ΔSM was calculated. The maximum -ΔSM reaches 7.8, 12.7 and 14.4 J/kg K for field range of 0-2 T, 0-5 T and 0-7 T, respectively. Accordingly, the value of RC (refrigerant capacity is 99, 289 and 432 J/kg for above field ranges. The large MCE of HoCo3B2 compound indicates its potential application for magnetic refrigeration in low temperature range.

Temperature dependent luminescence Cr3+doped GdAl3(BO3)4 and YAl3(BO3)4

NARCIS (Netherlands)

Malysa, B.; Meijerink, A; Jüstel, Thomas

Chromium activated YAl3(BO3)4 (YAB) and GdAl3(BO3)4 (GAB) were synthesized and show efficient broad band near infrared emission under excitation in the UV, blue and orange spectral regions. Temperature dependent luminescence measurements for GAB:1%Cr3+ and YAB:1%Cr3+ reveal high quenching

Preparation of Ti3C2 and Ti2C MXenes by fluoride salts etching and methane adsorptive properties

Science.gov (United States)

Liu, Fanfan; Zhou, Aiguo; Chen, Jinfeng; Jia, Jin; Zhou, Weijia; Wang, Libo; Hu, Qianku

2017-09-01

Here we reported the preparation of Ti3C2 MXene and Ti2C MXene by etching Ti3AlC2 and Ti2AlC with various fluoride salts in hydrochloric acid (HCl), including lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF), and ammonium fluoride (NH4F). As-prepared Ti2C was further delaminated by urea, dimethylsulfoxide or ammonium hydroxide. Based on theoretical calculation and XPS results, the type of positive ions (Li+, Na+, K+, or NH4+) in etchant solution affect the surface structure of prepared MXene, which, in turn, affects the methane adsorption properties of MXene. The highest methane adsorption capacity is 8.5 cm3/g for Ti3C2 and 11.6 cm3/g for Ti2C. MXenes made from LiF and NH4F can absorb methane under high pressure and can keep methane under normal pressure, these MXenes may have important application on capturing methane or other hazardous gas molecules. MXenes made from NaF and KF can absorb methane under high pressure and release methane under low pressure. They can have important application in the adsorb storage of nature gas.

Fluoride Stimulates the Proliferation of Osteoclasts in vitro by Upregulating MCM3

Directory of Open Access Journals (Sweden)

Shengbin Bai

2016-06-01

Full Text Available We have previously shown that the expression of the minichromosome maintenance protein 3 (MCM3 gene was upregulated in lymphocytes of patients with skeletal fluorosis. We speculated that increased MCM3 expression may be contribute to osteopathy in patients with skeletal fluorosis. Here, we investigated the effect of fluoride on the proliferation of osteoclasts derived from RAW264.7 cells and the involvement of MCM3. Our MTT assays showed that 0.25 mM NaF markedly stimulated the proliferation of RAW264.7 cells. The RT-PCR and immunoblotting assays revealed that 0.25 mM NaF upregulated MCM3 expression in RAW264.7 cells. The MTT assays additionally demonstrated that stimulation with MCM3 potentiated the effect of fluorine on the proliferation of RAW264.7 cells. These results demonstrated that fluoride at clinical relevant concentration upregulates MCM3 expression in osteoclasts in vitro. We are currently conducting a series of experiments to examine whether increased MCM3 in osteoclasts indeed contributes to osteopathy in skeletal fluorosis.

Relationship between water, urine and serum fluoride and fluorosis in school children of Jhajjar District, Haryana, India

Science.gov (United States)

Kumar, Sunil; Lata, Suman; Yadav, Jyoti; Yadav, J. P.

2017-10-01

The present study was undertaken to determine the relationship between fluoride in water, urine and serum and dental fluorosis. The fluoride level in water and urine were measured spectrophotometrically by using acid zirconyl and SPADNS reagents, while the fluoride level in serum was determined by ion selective electrode meter. Dental fluorosis survey was conducted with the help of Performa prescribed by Rajiv Gandhi Drinking Water Mission and the use of Tooth Surface Index for Fluorosis. Mean fluoride values in water samples of Jhajjar City and Dadanpur and Dariyapur villages of Jhajjar District were measured to be 2.17 (range from 1.92 to 2.60 mg/L), 2.81 (range from 2.53 to 3.14 mg/L) and 2.22 mg/L (range from 1.63 to 3.33 mg/L), respectively. The mean fluoride values in the urine samples of children were found to be 1.51 (range from 0.05 to 2.64 mg/L), 1.71 (range from 0.69 to 2.80 mg/L) and 1.45 mg/L (range from 0.31 to 2.50 mg/L) at Jhajjar City and Dadanpur and Dariyapur sites, respectively. Serum fluoride was detected in the blood samples of children, who have high urinary fluoride at these three sites. The mean serum fluoride level was reported to be 0.15, 0.34 and 0.17 mg/L, respectively. A total of 842 children were also analyzed for dental fluorosis. The mean values of fluorosis-affected children in Jhajjar, Dadanpur and Dariyapur were 51.90, 94.63 and 36.84 %, respectively. A significantly positive correlation between water, urine, serum fluoride concentration and fluorosis was seen.

Studies of the energy transfer processes from Er{sup 3+} and Ho{sup 3+} to Nd{sup 3+}, Tb{sup 3+} or Eu{sup 3+} in LiYF{sub 4} crystal and ZBLAN glass for the laser media optimization operating near 3{mu}m region; Estudos dos processos de transferencia de energia dos ions de Er{sup 3+} e Ho{sup 3+} para os ions de Nd{sup 3+}, Tb{sup 3+} e Eu{sup 3+} no cristal de LiYF{sub 4} e no vidro ZBLAN para a otimizacao de meios laser ativos que operam na regiao de 3{mu}m

Energy Technology Data Exchange (ETDEWEB)

Jagosich, Fabio Henrique

2006-07-01

The energy transfer processes (ET) from the {sup 4}I{sub 13/2}; {sup 4}I{sub 11/2} levels of Er{sup 3+} and {sup 5}I{sub 6} levels of Ho{sup 3+} ions in LiYF{sub 4} (YLF) crystal and ZBLAN glass to Nd{sup 3+}, Tb{sup 3+} or Eu{sup 3+} deactivators ions were studied. The micro parameters of these energy transfer processes were determined using the overlap integral method, and showed that Eu{sup 3+} ion is the best deactivator of the first excited state of the Ho{sup 3+} in YLF, and Nd{sup 3+} is the best deactivator of the Er{sup 3+} in YLF and ZBLAN materials. The 1.5 and 2.7{mu}m emissions of Er{sup 3+} and 2.1 and 2.9{mu}m fluorescence of Ho{sup 3+} were measured using short laser pulses excitations from a tunable OPO pumped 2w-Nd:YAG laser system. We proposed a criterion for discriminating the energy transfer processes assisted by excitation migration (diffusion or hopping) among donors. It was observed that diffusion model describes the ET process from the second excited state of the donor (Er{sup 3+} or Ho{sup 3+}) independently of the C{sub D-D}/C{sub D-A} ratio, while the hopping model can describe the ET process involving the first excited state of donor. We proposed a modification of the hopping model in order to describe the experimental results for systems having C{sub D-D}/C{sub D-A} {>=} 10. Using the ET parameters, we determined that the best systems for laser action at 3{mu}m are the Ho:Eu:YLF, Ho:Nd:YLF and Er:Nd:YLF systems. On the other hand, we found that Er{sup 3+} doped (1.5 mol%) ZBLAN glasses, single and co-doped with Nd{sup 3+}, Tb{sup 3+} or Eu{sup 3+}, do not show potential for laser action at 2.8{mu}m. The up-conversion processes were studied in Er:YLF systems as a function of the Er{sup 3+} concentration, and the excited state absorption (ESA) and up conversion by energy transfer (ETU) processes were discriminated using a time resolved fluorescence decays. It was observed that 980 nm is the most convenient wavelength for pumping the Er

Fabrication of Y{sub 2}Ti{sub 2}O{sub 7}:Yb{sup 3+},Ho{sup 3+} nanoparticles by a gel-combustion approach and upconverting luminescent properties

Energy Technology Data Exchange (ETDEWEB)

Chen, Zhongsheng, E-mail: zhshcheng@ecit.cn [State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China Institute of Technology, Nanchang, Jiangxi 330013 (China); Wang, Min; Wang, Haiqing; Le, Zhanggao; Huang, Guolin; Zou, Lixia; Liu, Zhirong [State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China Institute of Technology, Nanchang, Jiangxi 330013 (China); Wang, Dianyuan; Wang, Qingkai [College of Science, Jiujiang University, Jiujiang, Jiangxi 332005 (China); Gong, Weiping [Electronic Science Department, Huizhou University, Huizhou, Guangdong 516001 (China)

2014-09-01

Highlights: • Co-doped (Y{sub 0.99−x}Ho{sub 0.01}Yb{sub x}){sub 2}Ti{sub 2}O{sub 7} nanophosphors were fabricated by gel-combustion method. • The effect of calcination and Yb{sup 3+} doping on upconverting spectra of nanophosphors was studied. • The dependence of upconverting intensity on the excitation power was examined. - Abstract: Yb{sup 3+}, Ho{sup 3+} co-doped pyrochlore-structured (Y{sub 0.99−x}Ho{sub 0.01}Yb{sub x}){sub 2}Ti{sub 2}O{sub 7} (x = 0, 2.5, 5.0, 7.5, 10.0 and 12.5 mol%) nanoparticles (NPs) were successfully fabricated via a gel-combustion approach. The products as-obtained were characterized by various techniques, i.e. X-ray diffraction, transmission electron microscope, Fourier transformed infrared spectra and upconverting spectra. The results indicate that the bright green (∼540 nm) and red (∼660 nm) emissions are observed in Y{sub 2}Ti{sub 2}O{sub 7}:Ho{sup 3+},Yb{sup 3+} NPs under the 980 nm excitation, which is ascribed to the radiative transitions ({sup 5}F{sub 4},{sup 5}S{sub 2}) → {sup 5}I{sub 8} and {sup 5}F{sub 5} → {sup 5}I{sub 8} of Ho{sup 3+} ions, respectively. It is also found that the calcining temperature and Yb{sup 3+} ion doping level have a great influence on the upconverting spectra of (Y{sub 0.99−x}Ho{sub 0.01}Yb{sub x}){sub 2}Ti{sub 2}O{sub 7} NPs. The emission intensities increase initially and then fall down from 800 to 1000 °C. The optimum doping level of Yb{sup 3+} ions is 7.5 mol%, and the intensity of upconverting emissions for (Y{sub 0.915}Ho{sub 0.01}Yb{sub 0.075}){sub 2}Ti{sub 2}O{sub 7} NPs is enhanced by the fold of 32 compared to the Yb{sup 3+}-free samples. The dependence of upconverting intensity on the excitation power reveals the contribution of two photons to both the green and red upconverting process under lower excitation power, and the possible upconverting mechanisms have been proposed accordingly.

Single crystal polarized neutron diffraction study of the magnetic structure of HoFeO3.

Science.gov (United States)

Chatterji, T; Stunault, A; Brown, P J

2017-09-27

Polarised neutron diffraction measurements have been made on HoFeO 3 single crystals magnetised in both the [0 0 1] and [1 0 0] directions (Pbnm setting). The polarisation dependencies of Bragg reflection intensities were measured both with a high field of [Formula: see text] T parallel to [0 0 1] at [Formula: see text] K and with the lower field [Formula: see text] T parallel to [1 0 0] at [Formula: see text] K. A Fourier projection of magnetization induced parallel to [0 0 1], made using the hk0 reflections measured in 9 T, indicates that almost all of it is due to alignment of Ho moments. Further analysis of the asymmetries of general reflections in these data showed that although, at 70 K, 9 T applied parallel to [0 0 1] hardly perturbs the antiferromagnetic order of the Fe sublattices, it induces significant antiferromagnetic order of the Ho sublattices in the [Formula: see text] plane, with the antiferromagnetic components of moment having the same order of magnitude as the induced ferromagnetic ones. Strong intensity asymmetries measured in the low temperature [Formula: see text] structure with a lower field, 0.5 T [Formula: see text] [1 0 0] allowed the variation of the ordered components of the Ho and Fe moments to be followed. Their absolute orientations, in the [Formula: see text] domain stabilised by the field were determined relative to the distorted perovskite structure. This relationship fixes the sign of the Dzyalshinski-Moriya (D-M) interaction which leads to the weak ferromagnetism. Our results indicate that the combination of strong y-axis anisotropy of the Ho moments and Ho-Fe exchange interactions breaks the centrosymmetry of the structure and could lead to ferroelectric polarization.

Effect of concentration variation on 2.0 μm emission of Ho3+-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 oxyfluorosilicate glasses

International Nuclear Information System (INIS)

Gelija, Devarajulu; Borelli, Deva Prasad Raju

2018-01-01

The concentration variation of Ho 3+ ion-doped SiO 2 -Al 2 O 3 -Na 2 CO 3 -SrF 2 -CaF 2 glasses has been prepared by conventional melt quenching method. The thermal stability of 1 mol % of Ho 3+ -doped oxyfluorosilicate glass has been calculated using the differential thermal analysis (DTA) spectra. The phenomenological Judd-Ofelt intensity parameters Ω λ (λ = 2, 4 and 6) were calculated for all concentrations of Ho 3+ ions. The luminescence spectra in visible region of Ho 3+ ion-doped glasses were recorded under the excitation wavelength of 452 nm. The spectra consists of several intense emission bands ( 5 F 4 , 5 S 2 ) → 5 I 8 (547 nm), 5 F 3 → 5 I 8 (647 nm), 5 F 5 → 5 I 7 (660 nm) and ( 5 F 4 , 5 S 2 ) → 5 I 7 (750 nm) in the range 500-780 nm. The fluorescence emission at ∝ 2.0 μm ( 5 I 7 → 5 I 8 ) was observed under the excitation of 488 nm Ar-ion laser. The stimulated emission cross section for 5 I 7 → 5 I 8 transition (∝ 2.0 μm) varies from 8.46 to 9.52 x 10 -21 cm 2 , as calculated by the Fuchtbauer-Ladenburg (FL) theory. However, Mc-Cumber theory was used to calculate emission cross section values about 4.24-5.75 x 10 -21 cm 2 for the 5 I 7 → 5 I 8 transition in all concentrations of Ho 3+ -doped oxyfluorosilicate glasses. Therefore, these results reveal that the 0.5 mol % of Ho 3+ -doped oxyfluorosilicate glasses, exhibiting higher emission cross section, has potentially been used for laser applications at ∝ 2.0 μm. (orig.)

Fluoride release and cariostatic potential of orthodontic adhesives with and without daily fluoride rinsing.

NARCIS (Netherlands)

Chin, M.Y.; Sandham, A.; Rumachik, E.N.; Ruben, J.L.; Huysmans, M.C.D.N.J.M.

2009-01-01

INTRODUCTION: In this study, we aimed to evaluate the fluoride-release profiles and caries lesion development in an enamel model with brackets cemented with 4 orthodontic adhesives with and without daily fluoride exposure. METHODS: Four orthodontic adhesives (Ketac Cem mu, 3M ESPE, Seefeld, Germany;

Fluoride release and cariostatic potential of orthodontic adhesives with and without daily fluoride rinsing

NARCIS (Netherlands)

Chin, Yeen; Sandham, John; Rumachik, Elena N.; Ruben, Jan L.; Huysmans, Marie-Charlotte D. N. J. M.

2009-01-01

Introduction: In this study, we aimed to evaluate the fluoride-release profiles and caries lesion development in an enamel model with brackets cemented with 4 orthodontic adhesives with and without daily fluoride exposure. Methods: Four orthodontic adhesives (Ketac Cem mu, 3M ESPE, Seefeld, Germany;

Lanthanide recognition: A Ho3+ potentiometric membrane sensor as a probe for determination of terazosin

International Nuclear Information System (INIS)

Ganjali, Mohammad Reza; Shams, Haniyeh; Faridbod, Farnoush; Hajiaghababaei, Leila; Norouzi, Parviz

2009-01-01

In this study, complexation of N'-(1-pyridin-2-ylmethylene)-2-furohydrazide (NFH) with some metal ions was investigated by conductometry and spectroscopy. Then, a Ho 3+ potentiometric membrane sensor was prepared based on the highly selective complexation between this ionophore and Ho 3+ . These new ionophores are more selective than the previously reported ones. In this work, for the first time, the proposed sensor was applied in indirect determination of the terazocine in its pharmaceutical formulation. The interest in constructing lanthanide sensors arises because they have similar ionic radii to calcium, but a higher charge density, which allows them to be used as probes to find the interactions between Ca 2+ and biologically important molecules.

Spectroscopic characterization and temporal dynamics of energy transfer process between Tm3+ -Ho3+ and Yb3+ -Tm3+ ions in LiYF4 and LiLuF4 crystals

International Nuclear Information System (INIS)

Tarelho, Luiz Vicente Gomes

2001-01-01

In this work, we perform spectroscopic studies to characterize the energy transfer processes occurring in rare-earth doped lithium fluoride systems, aiming the optimization of the population inversion of these media. Yb 3+ ion was used in order to probe the electron-phonon coupling in LiYF 4 , LiGdF 4 and LiLuF 4 matrices. In these systems it was obtained the average phononenergy, the vibronic transition probability and Huang-Rhys coupling constant. These parameters are dependent on the crystal host and the LiLuF 4 system presents excluded correlation effects, an electronic repulsion that weakens the vibronic coupling. The Tm:Ho:LiYF 4 system was studied under diode laser pumping at 796 nm, aiming the 2 μm emission optimization. The ideal conditions of concentration and laser power were determined favouring the latter emission. Upconversion processes of two photons were identified besides the energy transfer among ions. The dynamic processes of luminescence of donors and acceptors allowed one to classify the energy transfer process as an energy transfer process assisted by fast diffusion among donors. The spectroscopic study of the Yb:Tm:LiYF 4 allowed the determination of efficient non resonant transfer mechanisms between ( 2 F 5/2 ) Ytterbium level and ( 3 H 5 ) Thulium level, assisted by two phonon with hopping migration among donors ( Foerster-Burshtein model). The repopulation process of the Yb donor level is due to a cooperative sensitization between Yb-Tm pairs followed by an energy transfer process. (author)

Impact of ytterbium on photoluminescence from the modifier in TeO{sub 2}–ZnO:Ho{sup 3+} glass

Energy Technology Data Exchange (ETDEWEB)

Pandey, Anurag, E-mail: anuragpandey439@gmail.com; Kroon, R.E.; Kumar, Vinod; Swart, Hendrik C., E-mail: swarthc@ufs.ac.za

2016-01-01

The effect of incorporation of Yb{sup 3+} ions in Ho{sup 3+} doped TeO{sub 2}–ZnO glass prepared by a melt quenching method is discussed. The amorphous nature of the prepared glass was confirmed by X-ray diffraction analysis. The optical absorption spectrum displayed several peaks, which correspond to the dopant ions embedded into the TeO{sub 2}–ZnO glass. The photoluminescence emission spectra measured upon excitation with a 325 nm He–Cd laser revealed a broad emission band of the modifier (ZnO) along with other peaks of the Ho{sup 3+} ions. A comparison of codoped glass emission with the singly Ho{sup 3+} doped system showed significant enhancement of the ZnO emissions while the Ho{sup 3+} peaks were reduced. This may be due to the energy transfer involved between the dopant ions and the glass modifier at an excitation wavelength of 325 nm. The energy transfer mechanism is discussed with a suitable energy level structure and the colour of the light emitted from the glass has been examined by calculating the corresponding colour coordinates.

Luminescent lanthanide coordination polymers synthesized via in-situ hydrolysis of dimethyl-3,4-furandicarboxylate

International Nuclear Information System (INIS)

Greig, Natalie E.; Einkauf, Jeffrey D.; Clark, Jessica M.; Corcoran, Eric J.; Karram, Joseph P.; Kent, Charles A.; Eugene, Vadine E.; Chan, Benny C.; Lill, Daniel T. de

2015-01-01

Dimethyl-3,4-furandicarboxylate undergoes hydrolysis under hydrothermal conditions with lanthanide (Ln) ions to form two-dimensional coordination polymers, [Ln(C 6 H 2 O 5 )(C 6 H 3 O 5 )(H 2 O)] n (Ln=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). The resulting materials exhibit luminescent properties with quantum yields and lifetimes for the Eu(III) and Tb(III) compounds of 1.1±0.3% and 0.387±0.0001 ms, and 3.3±0.8% and 0.769±0.006 ms, respectively. Energy values for the singlet and triplet states were determined for dimethyl-3,4-furandicarboxylate and 3,4-furandicarboxylic acid. Excited state dynamics and structural features are examined to explicate the reported quantum yields. A series of other FDC structures is briefly presented. - Graphical abstract: A new two-dimensional coordination polymer derived from the in-situ hydrolysis of a furan dimethyl ester with lanthanide(III) ions was obtained in order to study its photophysical behavior when constructed from trivalent Eu and Tb. Quantum yields, lifetime measurements, and singlet/triplet state energies values were obtained. The nature of the material's excited state dynamics is examined and correlated to its structure in order to explain the overall luminescent efficiency of the system. - Highlights: • A new lanthanide–furandicarboxylate coordination polymer is presented. • Eu and Tb compounds display luminescent properties, albeit with low quantum yields. • Photophysical behavior explained through the compound's triplet state and structure. • Nonradiative deactivation of luminescence through high-energy oscillators was noted. • Molecular modeling of the organic moiety was conducted

Luminescent lanthanide coordination polymers synthesized via in-situ hydrolysis of dimethyl-3,4-furandicarboxylate

Energy Technology Data Exchange (ETDEWEB)

Greig, Natalie E.; Einkauf, Jeffrey D.; Clark, Jessica M.; Corcoran, Eric J.; Karram, Joseph P.; Kent, Charles A.; Eugene, Vadine E. [Department of Chemistry & Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 (United States); Chan, Benny C. [Department of Chemistry, The College of New Jersey, 2000 Pennington Road, Ewing, NJ 08628 (United States); Lill, Daniel T. de, E-mail: ddelill@fau.edu [Department of Chemistry & Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 (United States)

2015-05-15

Dimethyl-3,4-furandicarboxylate undergoes hydrolysis under hydrothermal conditions with lanthanide (Ln) ions to form two-dimensional coordination polymers, [Ln(C{sub 6}H{sub 2}O{sub 5})(C{sub 6}H{sub 3}O{sub 5})(H{sub 2}O)]{sub n} (Ln=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). The resulting materials exhibit luminescent properties with quantum yields and lifetimes for the Eu(III) and Tb(III) compounds of 1.1±0.3% and 0.387±0.0001 ms, and 3.3±0.8% and 0.769±0.006 ms, respectively. Energy values for the singlet and triplet states were determined for dimethyl-3,4-furandicarboxylate and 3,4-furandicarboxylic acid. Excited state dynamics and structural features are examined to explicate the reported quantum yields. A series of other FDC structures is briefly presented. - Graphical abstract: A new two-dimensional coordination polymer derived from the in-situ hydrolysis of a furan dimethyl ester with lanthanide(III) ions was obtained in order to study its photophysical behavior when constructed from trivalent Eu and Tb. Quantum yields, lifetime measurements, and singlet/triplet state energies values were obtained. The nature of the material's excited state dynamics is examined and correlated to its structure in order to explain the overall luminescent efficiency of the system. - Highlights: • A new lanthanide–furandicarboxylate coordination polymer is presented. • Eu and Tb compounds display luminescent properties, albeit with low quantum yields. • Photophysical behavior explained through the compound's triplet state and structure. • Nonradiative deactivation of luminescence through high-energy oscillators was noted. • Molecular modeling of the organic moiety was conducted.

Electronic excitation-induced structural, optical, and magnetic properties of Ni-doped HoFeO3 thin films

International Nuclear Information System (INIS)

Habib, Zubida; Ikram, Mohd; Mir, Sajad A.; Sultan, Khalid; Abida; Majid, Kowsar; Asokan, K.

2017-01-01

Present study investigates the electronic excitation-induced modifications in the structural, optical, and magnetic properties of Ni-doped HoFeO 3 thin films grown by pulsed laser deposition on LaAlO 3 substrates. Electronic excitations were induced by 200 MeV Ag 12+ ion beam. These thin films were then characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), UV-Vis spectroscopy, and magnetic measurements. X-ray diffraction analysis confirms that the crystallite growth occurs in the preferred (111) orientation with orthorhombic structure. The XRD results also show that the crystallite size decreases with ion irradiation. AFM results after irradiation show significant changes in the surface roughness and morphology of these films. The optical parameters measured from absorption measurements reveal reduction in the band gap with Ni doping and enhancement of band gap after irradiation. The magnetization vs field measurement at 75 K shows enhancement in saturation magnetization after irradiation for HoFe 1-x Ni x O 3 (x = 0.1 and 0.3) films compared to HoFeO 3 film. Present study shows electronic excitation induces significant changes in the physical properties of these films. (orig.)

Preparation and photophysical properties of luminescent nanoparticles based on lanthanide doped fluorides (LaF3:Ce3+, Gd3+, Eu3+), obtained in the presence of different surfactants

International Nuclear Information System (INIS)

Runowski, Marcin; Lis, Stefan

2014-01-01

Highlights: • Synthesis of nanocrystalline lanthanide fluorides doped with Eu 3+ ions. • Inorganic nanomaterials exhibiting bright red luminescence. • Luminescence enhancement by energy transfer (ET) from Ce 3+ → Gd 3+ to Eu 3+ ions. • Decreased agglomeration and morphology control using organic modifiers/surfactants. • Absolute and relative quantum yield (QY) comparison. - Abstract: A series of nanomaterials composed of LaF 3 :Ce 3+ 10%, Gd 3+ 30%, Eu 3+ 1% was synthesized via a facile co-precipitation approach. The reaction between appropriate lanthanide (Ln 3+ ) and fluoride ions resulted in the formation of crystalline, Ln 3+ doped fluorides and was performed in the presence of a series of organic modifiers, acting as surfactants and anti-agglomeration agents. Modifiers such as polyacrylic acid (PAA), ethylenediaminetetraacetic acid (EDTA), citric acid and oleylamine most significantly influenced the morphology and spectroscopic properties of the products. The product obtained in the presence of PAA was composed of the smallest nanoparticles (ca. 5–6 nm), with narrow size/shape distribution. All fluorides synthesized exhibited intensive, bright red luminescence under UV irradiation (λ ex ≈ 250 nm), because of the presence of Eu 3+ ions in their structure. The efficient intensity of luminescence was a result of indirect excitation, via energy transfer (ET) phenomena occurring in the system (Ce 3+ → Gd 3+ → Eu 3+ ). The structure and morphology of the obtained nanomaterials were established by powder X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) measurements. Optical properties of the obtained compounds were studied and discussed on the basis of excitation emission spectra and luminescence decay curves. On the basis of the performed measurements, luminescence quantum yield (absolute and relative) and radiative lifetimes were calculated and analyzed. FT-IR spectroscopy was applied to examine the presence of molecules of

Fluoride adsorption from aqueous solution by magnetic core-shell Fe{sub 3}O{sub 4}@alginate-La particles fabricated via electro-coextrusion

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yahui [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China); Engineering Research Center of Biomass Materials, Ministry of Education, Mianyang 621010, Sichuan (China); Lin, Xiaoyan, E-mail: lxy20100205@163.com [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China); Engineering Research Center of Biomass Materials, Ministry of Education, Mianyang 621010, Sichuan (China); Zhou, Quisheng [A State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Luo, Xuegang [Engineering Research Center of Biomass Materials, Ministry of Education, Mianyang 621010, Sichuan (China)

2016-12-15

Graphical abstract: The magnetic core-shell Fe{sub 3}O{sub 4}@Alg-La particles were fabricated successfully by a simple method of electro-coextrusion, and employed as an adsorbent for separation of fluoride from aqueous solution. - Highlights: • Magnetic core-shell Fe{sub 3}O{sub 4}@Alg-La particles were prepared by electro-coextrusion. • The maximum adsorption capacity for fluoride at 298.15 K was 45.230 mg/g. • The adsorbent has a good saturation magnetization value. • The adsorbent has a great potential in removing the fluoride. - Abstract: The magnetic core-shell Fe{sub 3}O{sub 4}@Alg-La particles were fabricated successfully by a simple method of electro-coextrusion, and employed as an adsorbent for separation of fluoride from aqueous solution. Main factors affecting the removal of fluoride, including pH, adsorbent dosage, initial concentration, temperature and contact time were investigated. The adsorption isotherm and adsorption kinetics were studied to understand the adsorption process in detail. The experimental data were fitted well by the non-linear Freundlich isotherm and linear pseudo-second-order model, the maximum fluoride adsorption capacity was 45.230 mg/g at pH 4, 298.15 K. Thermodynamic parameters indicated that the fluoride adsorption process was feasible and spontaneous. The presence of other anions like Cl{sup −}, SO{sub 4}{sup 2−}, HCO{sub 3}{sup −} and PO{sub 4}{sup 3−} had almost no effect on the fluoride adsorption. The adsorbent can be easily separated from the solution by a magnet. The magnetic core-shell Fe{sub 3}O{sub 4}@Alg-La particles before and after fluoride adsorption were studied by SEM, FTIR, EDX and XPS, which indicated that the adsorption mechanism may be related to electrostatic attraction and Lewis acid-base interaction.

Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses for ∼1.2 μm laser applications

Science.gov (United States)

Wang, Shunbin; Li, Chengzhi; Yao, Chuanfei; Jia, Shijie; Jia, Zhixu; Qin, Guanshi; Qin, Weiping

2017-02-01

Intense ∼1.2 μm fluorescence is observed in Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses under 915 nm laser diode excitation. The 1.2 μm emission can be ascribed to the transition 5I6→5I8 of Ho3+. With the introducing of BaF2, the content of OH in the glasses drops markedly, and the 1.2 μm emission intensity increases gradually as increasing the concentration percentage of BaF2. Furthermore, microstructured fibers based on the TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method, and a relative positive gain of ∼9.42 dB at 1175.3 nm is obtained in a 5 cm long fiber.

Removal of fluoride from aqueous nitric acid

International Nuclear Information System (INIS)

Pruett, D.J.; Howerton, W.B.; Mailen, J.C.

1981-06-01

Several methods for removing fluoride from aqueous nitric acid were investigated and compared with the frequently used aluminum nitrate-calcium nitrate (Ca 2+ -Al 3+ ) chemical trap-distillation system. Zirconium oxynitrate solutions were found to be superior in preventing volatilization of fluoride during distillation of the nitric acid, producing decontamination factors (DFs) on the order of 2 x 10 3 (vs approx. 500 for the Ca 2+ -Al 3+ system). Several other metal nitrate systems were tested, but they were less effective. Alumina and zirconia columns proved highly effective in removing HF from HF-HNO 3 vapors distilled through the columns; fluoride DFs on the order of 10 6 and 10 4 , respectively, were obtained. A silica gel column was very effective in adsorbing HF from HF-HNO 3 solutions, producing a fluoride DF of approx. 10 4

Fluoride in groundwater: toxicological exposure and remedies.

Science.gov (United States)

Jha, S K; Singh, R K; Damodaran, T; Mishra, V K; Sharma, D K; Rai, Deepak

2013-01-01

Fluoride is a chemical element that is found most frequently in groundwater and has become one of the most important toxicological environmental hazards globally. The occurrence of fluoride in groundwater is due to weathering and leaching of fluoride-bearing minerals from rocks and sediments. Fluoride when ingested in small quantities (dental health by reducing dental caries, whereas higher concentrations (>1.5 mg/L) may cause fluorosis. It is estimated that about 200 million people, from among 25 nations the world over, may suffer from fluorosis and the causes have been ascribed to fluoride contamination in groundwater including India. High fluoride occurrence in groundwaters is expected from sodium bicarbonate-type water, which is calcium deficient. The alkalinity of water also helps in mobilizing fluoride from fluorite (CaF2). Fluoride exposure in humans is related to (1) fluoride concentration in drinking water, (2) duration of consumption, and (3) climate of the area. In hotter climates where water consumption is greater, exposure doses of fluoride need to be modified based on mean fluoride intake. Various cost-effective and simple procedures for water defluoridation techniques are already known, but the benefits of such techniques have not reached the rural affected population due to limitations. Therefore, there is a need to develop workable strategies to provide fluoride-safe drinking water to rural communities. The study investigated the geochemistry and occurrence of fluoride and its contamination in groundwater, human exposure, various adverse health effects, and possible remedial measures from fluoride toxicity effects.

Theoretical evaluation of a continues-wave Ho3+:BaY2F8 laser with mid-infrared emission

Science.gov (United States)

Rong, Kepeng; Cai, He; An, Guofei; Han, Juhong; Yu, Hang; Wang, Shunyan; Yu, Qiang; Wu, Peng; Zhang, Wei; Wang, Hongyuan; Wang, You

2018-01-01

In this paper, we build a theoretical model to study a continues-wave (CW) Ho3+:BaY2F8 laser by considering both energy transfer up-conversion (ETU) and cross relaxation (CR) processes. The influences of the pump power, reflectance of an output coupler (OC), and crystal length on the output features are systematically analyzed for an end-pumped configuration, respectively. We also investigate how the processes of ETU and CR in the energy-level system affect the output of a Ho3+:BaY2F8 laser by use of the kinetic evaluation. The simulation results show that the optical-to-optical efficiency can be promoted by adjusting the parameters such as the reflectance of an output coupler, crystal length, and pump power. It has been theoretically demonstrated that the threshold of a Ho3+:BaY2F8 laser is very high for the lasing operation in a CW mode.

Spectroscopy and microchip laser operation of Tm, Ho:KYW crystals with different Ho concentrations

Science.gov (United States)

Gusakova, N. V.; Kurilchik, S. V.; Yasukevich, A. S.; Kisel, V. E.; Dashkevich, V. I.; Orlovich, V. A.; Pavlyuk, A. A.; Vatnik, S. M.; Bagaev, S. N.; Kuleshov, N. V.

2018-02-01

The spectroscopic properties of Tm, Ho:KYW crystals with different Ho concentrations were investigated. The diode-pumped microchip laser operation of Tm (5 at.%), Ho (0.5 at.%):KYW and Tm (5 at.%), Ho (1 at.%):KYW was demonstrated. The highest, to our knowledge, output power of 480 mW with slope efficiency of 31% for CW Tm (5 at.%), Ho (0.5 at.%):KYW microchip laser was obtained.

Scandium fluorides

International Nuclear Information System (INIS)

Melnikov, P.; Nalin, M.; Messaddeq, Y.

1997-01-01

A new modification of scandium fluoride has been synthesised. The compound is deficient in fluorine, with the composition ScF 2.76 . It belongs to the tetragonal system, lattice parameters being a=3.792 and c=6.740 A and may be obtained at low temperatures by the decomposition of the precursor NH 4 ScF 4 . The reaction is topotactic, tetragonal parameters of the precursor are a=4.021 and c=6.744 A. Structural relationships with various fluorides and ammonium aminofluorides are discussed. This synthesis route with IR-assisted decomposition should be considered as a soft-chemistry approach. (orig.)

Removal of fluoride from aqueous solution by adsorption on hydroxyapatite (HAp using response surface methodology

Directory of Open Access Journals (Sweden)

M. Mourabet

2015-11-01

Full Text Available A study on the adsorption of fluoride onto hydroxyapatite was conducted and the process parameters were optimized using Response Surface Methodology (RSM. Hydroxyapatite has been characterized by using different physicochemical methods. In order to determine the effects of process parameters namely temperature (20–40 °C, initial solution pH (4–11, adsorbent dose (0.1–0.3 g and initial fluoride concentration (10–20 mg L−1 on fluoride uptake from aqueous solution, a three-level, four-factor, Box–Behnken design has been employed. The second order mathematical model was developed by regression analysis of the experimental data obtained from 29 batch runs. The optimum pH, temperature, adsorbent dose and initial concentration were found by desirability function to be 4.16, 39.02 °C, 0.28 g and 20 mg L−1, respectively. Fluoride removal was 86.34% at the optimum combination of process parameters. Dynamic adsorption data were applied to pseudo-first-order and pseudo-second-order rate equations. The time data fitted well to pseudo second order kinetic model. According to the correlation coefficients, the adsorption of fluoride on the hydroxyapatite was correlated well with the Langmuir and Freundlich models.

Sulfochlorphenol S as reagent for direct photometric determination of fluorides

International Nuclear Information System (INIS)

Dzhashi, D.O.; Dedkova, V.P.; Savvin, S.B.

1978-01-01

The system of zirconium-sulfochlorphenol S-fluoride was studied by the spectrophotometry method. The effect of pH, temperature and time on the formation of zirconium complexes with sulfochlorphenol S was investigated. A comparison of the above method of determining fluorides with other methods (using alizarinecomplexonate, quinalizarincomplexonate, cerium chelates, lanthanum, arsenazo 3) is presented. The sensitivity of determining fluorides with arsenazo 3 is lower than that with sulfochlorphenol S. The molar absorption coefficient is 3x10 4 , the reaction of determining fluorides with the aid of sulfochlorphenol S is highly selective. The method was used to determine fluorides in the supply water, zirconium solutions and electrolyzer cell. The range of concentration determination for fluorides is 0-3 μg/25 ml

Fluoride exposure and indicators of thyroid functioning in the Canadian population: implications for community water fluoridation.

Science.gov (United States)

Barberio, Amanda M; Hosein, F Shaun; Quiñonez, Carlos; McLaren, Lindsay

2017-10-01

There are concerns that altered thyroid functioning could be the result of ingesting too much fluoride. Community water fluoridation (CWF) is an important source of fluoride exposure. Our objectives were to examine the association between fluoride exposure and (1) diagnosis of a thyroid condition and (2) indicators of thyroid functioning among a national population-based sample of Canadians. We analysed data from Cycles 2 and 3 of the Canadian Health Measures Survey (CHMS). Logistic regression was used to assess associations between fluoride from urine and tap water samples and the diagnosis of a thyroid condition. Multinomial logistic regression was used to examine the relationship between fluoride exposure and thyroid-stimulating hormone (TSH) level (low/normal/high). Other available variables permitted additional exploratory analyses among the subset of participants for whom we could discern some fluoride exposure from drinking water and/or dental products. There was no evidence of a relationship between fluoride exposure (from urine and tap water) and the diagnosis of a thyroid condition. There was no statistically significant association between fluoride exposure and abnormal (low or high) TSH levels relative to normal TSH levels. Rerunning the models with the sample constrained to the subset of participants for whom we could discern some source(s) of fluoride exposure from drinking water and/or dental products revealed no significant associations. These analyses suggest that, at the population level, fluoride exposure is not associated with impaired thyroid functioning in a time and place where multiple sources of fluoride exposure, including CWF, exist. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

White light emission and effect of annealing on the Ho3+–Yb3+ codoped BaCa2Al8O15 phosphor

International Nuclear Information System (INIS)

Kumari, Astha; Rai, Vineet Kumar

2015-01-01

Graphical abstract: The upconversion emission spectra of the Ho 3+ /Yb 3+ doped/codoped BaCa 2 Al 8 O 15 phosphors with different doping concentrations of Ho 3+ /Yb 3+ ions along with UC emission spectrum of the white light emitting phosphor annealed at 800 °C. - Highlights: • BaCa 2 Al 8 O 15 phosphors codoped with Ho 3+ –Yb 3+ have been prepared by combustion method. • Phosphor annealed at 800 °C, illuminate an intense white light upon NIR excitation. • The sample annealed at higher temperatures emits in the pure green region. • The colour emitted persists in the white region even at high pump power density. • Developed phosphor is suitable for making upconverters and WLEDs. - Abstract: The BaCa 2 Al 8 O 15 (BCAO) phosphors codoped with suitable Ho 3+ –Yb 3+ dopant concentration prepared by combustion method illuminate an intense white light upon near infrared diode laser excitation. The structural analysis of the phosphors and the detection of impurity contents have been performed by using the X-Ray Diffraction, FESEM and FTIR analysis. The purity of white light emitted from the sample has been confirmed by the CIE chromaticity diagram. Also, the white light emitted from the sample persists with the variation of pump power density. The phosphors emit upconversion (UC) emission bands in the blue, green and red region (three primary colours required for white light emission) along with one more band in the near infrared region of the electromagnetic spectrum. On annealing the white light emitting sample at higher temperatures, the sample starts to emit green colour and also the intensity of green and red UC emission bands get enhanced largely.

Holmium laser lithotripsy (HoLL) of ureteral calculi

Science.gov (United States)

Kuntz, Rainer M.; Lehrich, Karin; Fayad, Amr

2001-05-01

The effectiveness and side effects of ureteroscopic HoLL of ureteral stones should be evaluated. In 63 patients (17 female, 46 males) a total of 75 stones of 3-20 mm diameter were treated with ureteroscopic HoLL. 18.7 percent of stones were located in the proximal third, 24.0 percent in the middle third and 57.3 percent in the distal third of the ureter. HoLL was performed with small diameter semirigid and flexible ureteroscopes, 220 or 365 nm flexible laser fibers and a holmium:YAG laser at a power of 5-15 W (0.5-1.0 J, 10- 15 Hz). 47 of 63 patients (74.6 percent) were immediately free of stones, and 8 others (12.6 percent) lost their residual fragments spontaneously within two weeks. Another 2 patients received additional chmolitholysis for uric acid stone fragments, i.e. 90.5 percent of patients were stone free by one sitting of ureterscopic HoLL. Of the remaining 6 patients (9.5 percent) who still had residual calculi 4 weeks after HoLL, 2 asymptomatic patients refused any additional treatment, 2 patients preferred treatment with ESWL, and 2 patients had a successful second HoLL, thereby raising the success rate of ureteroscopic HoLL to 93.7 percent. 2 patients showed contrast medium extravasation on retrograde ureterograms, due to guide wire perforation. No ureteral stricture occurred. In conclusion, transurethral ureteroscopic HoLL proved to be a safe and successful minimal invasive treatment of ureteral calculi.

Fluoride uptake into the developing enamel and dentine of sheep incisors following daily ingestion of fluoridated milk or water

International Nuclear Information System (INIS)

Cuttress, T.W.; Suckling, G.W.; Gao, J.; Coote, G.E.

1996-01-01

The caries preventive action of fluoride is common knowledge, although some of the mechanisms involved remain equivocal. At present, raised local levels of fluoride at, or in, the surface of tooth enamel is the most commonly accepted explanation of the anti-cariogenic action of fluoride. However, fluoride incorporated as fluorapatite into the tooth during its formation remains a possible alternative or complementary anti-cariogenic mechanism. If so, regular ingestion of fluoride during tooth formation is beneficial. Although use of fluoridated water is the preferred method in public health programmes, access to suitable potable water is required, and often this in not feasible. Fresh, preserved, or dried cow's milk products are widely used as nutritional and dietary items in most populations, particularly for young children. Milk is a practical, controllable means for regular delivery of fluoride. Processing of milk is commonly centralised and uses standardised conditions, allowing easy supplementation of fluoride for distribution to communities. The purpose of this study was to resolve the question of availability of fluoride ingested in milk compared with fluoride ingested in water by measuring fluoride deposition in the developing permanent incisors of young sheep. Incisors were analysed using a proton microprobe. (author). 18 refs., 1 tabs., 3 figs

Direct observation of low energy nuclear spin excitations in HoCrO3 by high resolution neutron spectroscopy.

Science.gov (United States)

Chatterji, T; Jalarvo, N; Kumar, C M N; Xiao, Y; Brückel, Th

2013-07-17

We have investigated low energy nuclear spin excitations in the strongly correlated electron compound HoCrO3. We observe clear inelastic peaks at E = 22.18 ± 0.04 μeV in both energy loss and gain sides. The energy of the inelastic peaks remains constant in the temperature range 1.5-40 K at which they are observed. The intensity of the inelastic peak increases at first with increasing temperature and then decreases at higher temperatures. The temperature dependence of the energy and intensity of the inelastic peaks is very unusual compared to that observed in other Nd, Co, V and also simple Ho compounds. Huge quasielastic scattering appears at higher temperatures presumably due to the fluctuating electronic moments of the Ho ions that get increasingly disordered at higher temperatures. The strong quasielastic scattering may also originate in the first Ho crystal-field excitations at about 1.5 meV.

Direct detection of OH formation in the reactions of HO2 with CH3C(OO2 and other substituted peroxy radicals

Directory of Open Access Journals (Sweden)

J. N. Crowley

2008-08-01

Full Text Available This work details the first direct observation of OH as a product from (R1: HO2+CH3C(OO2→(products, which has generally been considered an atmospheric radical termination process. The technique of pulsed laser photolysis radical generation, coupled to calibrated laser induced fluorescence detection was used to measure an OH product yield for (R1 of α1(298 K=(0.5±0.2. This study of (R1 included the measurement of a rate coefficient k1(298 K=(1.4±0.5×10−11cm3 molecule−1 s−1, substantially reducing the uncertainties in modelling this important atmospheric reaction. OH was also detected as a product from the reactions of HO2 with three other carbonyl-containing peroxy radicals, albeit at smaller yield, e.g. (R2: HO2+CH3C(OCH2O2→(products, α2≈0.15. By contrast, OH was not observed (α<0.06 as a major product from reactions where carbonyl functionality was absent, e.g. HO2+HOCH2CH2O2 (R8, and HO2+CH3CH(OHCH2O2 (R9.

Risk Assessment of Fluoride Intake from Tea in the Republic of Ireland and its Implications for Public Health and Water Fluoridation

Science.gov (United States)

Waugh, Declan T.; Potter, William; Limeback, Hardy; Godfrey, Michael

2016-01-01

The Republic of Ireland (RoI) is the only European Country with a mandatory national legislation requiring artificial fluoridation of drinking water and has the highest per capita consumption of black tea in the world. Tea is a hyperaccumulator of fluoride and chronic fluoride intake is associated with multiple negative health outcomes. In this study, fifty four brands of the commercially available black tea bag products were purchased and the fluoride level in tea infusions tested by an ion-selective electrode method. The fluoride content in all brands tested ranged from 1.6 to 6.1 mg/L, with a mean value of 3.3 mg/L. According to our risk assessment it is evident that the general population in the RoI is at a high risk of chronic fluoride exposure and associated adverse health effects based on established reference values. We conclude that the culture of habitual tea drinking in the RoI indicates that the total cumulative dietary fluoride intake in the general population could readily exceed the levels known to cause chronic fluoride intoxication. Evidence suggests that excessive fluoride intake may be contributing to a wide range of adverse health effects. Therefore from a public health perspective, it would seem prudent and sensible that risk reduction measures be implemented to reduce the total body burden of fluoride in the population. PMID:26927146

Fluoride

Science.gov (United States)

Opalescence® ... Fluoride is used to prevent tooth decay. It is taken up by teeth and helps to strengthen ... and block the cavity-forming action of bacteria. Fluoride usually is prescribed for children and adults whose ...

FLUORIDE CONTENT OF COMMERCIALLY AVAILABLE SOY MILK PRODUCTS IN THAILAND.

Science.gov (United States)

Rirattanapong, Opas; Rirattanapong, Praphasri

2016-01-01

Abstract. In Thailand, the consumption of soy milk products is common but there is limited data about their fluoride content. The purpose of this study was to es- timate the fluoride content of soy milk products available in Thailand. Fluoride content was determined for 76 brands of soy milk using a F-ion-specific electrode. The fluoride concentrations ranged from 0.01 to 3.78 μg/ml. The fluoride content was not related to sugar content, soy bean content or the sterilization process. Among 3 brands of soy milk containing tea powder extract, the fluoride content was high (1.25 to 3.78 μg/ml). Most brands of soy milk tested in our study had fluoride content below the optimal daily intake but brands containing tea powder extract if consumed by children may increase their risk for fluorosis.

PREPARATION AND CHARACTERIZATION OF STRONTIUM FLUORIDE POWDERS ACTIVATED BY NEODYMIUM FLUORIDE

Directory of Open Access Journals (Sweden)

S. V. Kuznetsov

2015-07-01

Full Text Available Subject of Study. The paper deals with preparation processes of ultradisperse, homogeneous powder Sr1-хNdхF2+х (х= 0.003-0.2, with use of ammonium fluoride as the fluorinating agent taken over 114-120 % from stoichiometry. Method. Nitrate of strontium, neodymium nitrate hexahydrate, with the content equal to 99. 99 % of the basic substance and ammonium fluoride were used as the source of substances. Activated powders of strontium fluoride were obtained by the method of deposition from aqueous solutions by washing the precipitate with a solution of ammonium fluoride, taken over 114 - 120% from stoichiometry. The washed precipitate was centrifuged for 5-7 min, dried in the air at 30-350 C. Heat treatment of the dried precipitate was carried out in two stages: the first stage at the temperature of 200- 2500 C for 0.5-1 hour, the second one at 550- 6000 C for 2-3 hours. X-ray analysis of the synthesized samples was carried out on a Bruker D8 Advance diffractometer, radiation Cu K. The size and shape measuring of the particles of activated strontium fluoride was carried out by means of electron microscope Carl Zeiss NVision 40. The content of neodymium in activated powders of strontium fluoride was determined by the method of spectral emission analysis on the device LEA - S500. Chemical analysis for determination of ammonium ion (NH4+ content in the obtained samples was performed by the method of Kjeldahl. Calculations of lattice parameters, size of coherent scattering regions and the values of micro-deformations were carried out by TOPAS program. Main Results. Preparation processes of ultradisperse, homogeneous powder Sr1-хNdхF2+х (х= 0.003-0.2, with use of ammonium fluoride as the fluorinating agent taken over 114-120 % from stoichiometry, provides obtaining the firm solution Sr1-x-yNdx(NH4yF2+x-y of the cubic fluorite structure. It has been found out that the morphology and size of the resulting product depend on the quantity of

The electron capture in 163Ho experiment - ECHo

Science.gov (United States)

Gastaldo, L.; Blaum, K.; Chrysalidis, K.; Day Goodacre, T.; Domula, A.; Door, M.; Dorrer, H.; Düllmann, Ch. E.; Eberhardt, K.; Eliseev, S.; Enss, C.; Faessler, A.; Filianin, P.; Fleischmann, A.; Fonnesu, D.; Gamer, L.; Haas, R.; Hassel, C.; Hengstler, D.; Jochum, J.; Johnston, K.; Kebschull, U.; Kempf, S.; Kieck, T.; Köster, U.; Lahiri, S.; Maiti, M.; Mantegazzini, F.; Marsh, B.; Neroutsos, P.; Novikov, Yu. N.; Ranitzsch, P. C. O.; Rothe, S.; Rischka, A.; Saenz, A.; Sander, O.; Schneider, F.; Scholl, S.; Schüssler, R. X.; Schweiger, Ch.; Simkovic, F.; Stora, T.; Szücs, Z.; Türler, A.; Veinhard, M.; Weber, M.; Wegner, M.; Wendt, K.; Zuber, K.

2017-06-01

Neutrinos, and in particular their tiny but non-vanishing masses, can be considered one of the doors towards physics beyond the Standard Model. Precision measurements of the kinematics of weak interactions, in particular of the 3H β-decay and the 163Ho electron capture (EC), represent the only model independent approach to determine the absolute scale of neutrino masses. The electron capture in 163Ho experiment, ECHo, is designed to reach sub-eV sensitivity on the electron neutrino mass by means of the analysis of the calorimetrically measured electron capture spectrum of the nuclide 163Ho. The maximum energy available for this decay, about 2.8 keV, constrains the type of detectors that can be used. Arrays of low temperature metallic magnetic calorimeters (MMCs) are being developed to measure the 163Ho EC spectrum with energy resolution below 3 eV FWHM and with a time resolution below 1 μs. To achieve the sub-eV sensitivity on the electron neutrino mass, together with the detector optimization, the availability of large ultra-pure 163Ho samples, the identification and suppression of background sources as well as the precise parametrization of the 163Ho EC spectrum are of utmost importance. The high-energy resolution 163Ho spectra measured with the first MMC prototypes with ion-implanted 163Ho set the basis for the ECHo experiment. We describe the conceptual design of ECHo and motivate the strategies we have adopted to carry on the present medium scale experiment, ECHo-1K. In this experiment, the use of 1 kBq 163Ho will allow to reach a neutrino mass sensitivity below 10 eV/ c 2. We then discuss how the results being achieved in ECHo-1k will guide the design of the next stage of the ECHo experiment, ECHo-1M, where a source of the order of 1 MBq 163Ho embedded in large MMCs arrays will allow to reach sub-eV sensitivity on the electron neutrino mass.

Fluoride Concentration in Water, Cow Milk and Cow Urine from Smallholder Dairy Farms in Kiambu- Kenya

International Nuclear Information System (INIS)

Gikunju, J.K.; Maitho, T.E.; Kyule, M.N.; Mitema, E.S.; Mugera, G.M.

1999-01-01

Kiambu district is situated in central part of Kenya. most of the available land is suitable for agricultural use. majority of the farmers are small scale or subsistence farmers and they are involve in a variety of livestock activities e.g. dairy production, pig production and others in combination or as separate operations. excessive fluoride ingestion can cause specific dental and skeletal lesions and in severe cases adversely influence the health and productivity performance of domestic animals.therefore a study was designed to investigate the levels of flouride in urine, milk and water samples from small scale dairy farms in Kiambu. Water, cow urine and milk samples were collected in clean plastic containers from 84 small scale farms belonging to 6 dairy farmers co-operative societies (DFCs). The DFCs in this study were Kiambaa, Lari, Nderi, Kikuyu, Chania and Limuru. The fluoride concentration in water milk and urine were analysed using the potentiometric method of fluoride ion specific electrode. overall urine contained the highest fluoride concentration while milk contained the lowest fluoride levels. Fluoride levels in water, milk and urine were significantly different, (P>0.05). The mean fluoride concentration in water from all societies was 0.29 ppm while the mean fluoride concentration in milk 0.05 ppm. urine samples had the highest fluoride concentration, (1.5 ppm). The cooperative specific mean fluoride concentrations arranged in descending order were as follow: Nderi (2.8 ppm), Kikuyu (2.4 ppm), Kiambaa(1.9 ppm), Chania (1.6 ppm), Limuru (1.3 ppm) and Lari (1.0 ppm). The maximum fluoride concentration encountered in water in this study was 3.4 ppm, however adverse productivity has been reported in dairy animals consuming as low as 2.15 ppm in drinking water. The mean milk production in in kilograms per day per cow ranged from 2.5 to 6.9 when all six dairy co-operative societies were taken into consideration. this is far below the expected production

Adverse effects of fluoride towards thyroid hormone metabolism

Directory of Open Access Journals (Sweden)

Enggar Abdullah Idris MZ

2008-03-01

Full Text Available An easily ionized fluoride compound like Sodium Fluoride (NaF has been used thus far as a dental caries prevention substance. However, fluoride ions also have a negative effect because it is very toxic. Several types of research on the effect of fluoride on guinea pigs and human beings indicate the presence synthesis obstruction of T3 and T4 that causes declined production, known as hypothyroidism. Hypothyroidism condition may obstruct tissue growth process and metabolism so as to impact various body organ systems. Preventive efforts against hypothyroidism caused by fluoride include avoiding diffusible fluoride compound intake, like NaF, in a long run systemic use, whereas efforts to overcome fluoride intoxication include consuming food that is rich in calcium, vitamin D, and antioxidant.

Atmospheric chemistry of CH3CHF2 (R-152a): mechanism of the CH3CF2O2+HO2 reaction

DEFF Research Database (Denmark)

Hashikawa, Y; Kawasaki, M; Andersen, Mads Peter Sulbæk

2004-01-01

FTIR smog chamber techniques have been used to investigate the mechanism of the reaction of CH3CF2O2 with HO2 radicals in 100-700 Torr of synthetic air at 296 K. The reaction gives CH3CF2OOH and COF2 in molar yields of 0.53 +/- 0.05 and 0.47 +/- 0.05, respectively. Results are discussed with resp......FTIR smog chamber techniques have been used to investigate the mechanism of the reaction of CH3CF2O2 with HO2 radicals in 100-700 Torr of synthetic air at 296 K. The reaction gives CH3CF2OOH and COF2 in molar yields of 0.53 +/- 0.05 and 0.47 +/- 0.05, respectively. Results are discussed...

Electronic excitation-induced structural, optical, and magnetic properties of Ni-doped HoFeO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Habib, Zubida [National Institute of Technology, Department of Chemistry, Srinagar (India); National Institute of Technology, Department of Physics, Srinagar (India); Ikram, Mohd; Mir, Sajad A. [National Institute of Technology, Department of Physics, Srinagar (India); Sultan, Khalid [Central University of Kashmir, Department of Physics, Srinagar (India); Abida [Govt Degree College for Women, Department of Physics, Anantnag, Kashmir (India); Majid, Kowsar [National Institute of Technology, Department of Chemistry, Srinagar (India); Asokan, K. [Inter University Accelerator Centre, New Delhi (India)

2017-06-15

Present study investigates the electronic excitation-induced modifications in the structural, optical, and magnetic properties of Ni-doped HoFeO{sub 3} thin films grown by pulsed laser deposition on LaAlO{sub 3} substrates. Electronic excitations were induced by 200 MeV Ag{sup 12+} ion beam. These thin films were then characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), UV-Vis spectroscopy, and magnetic measurements. X-ray diffraction analysis confirms that the crystallite growth occurs in the preferred (111) orientation with orthorhombic structure. The XRD results also show that the crystallite size decreases with ion irradiation. AFM results after irradiation show significant changes in the surface roughness and morphology of these films. The optical parameters measured from absorption measurements reveal reduction in the band gap with Ni doping and enhancement of band gap after irradiation. The magnetization vs field measurement at 75 K shows enhancement in saturation magnetization after irradiation for HoFe{sub 1-x}Ni{sub x}O{sub 3} (x = 0.1 and 0.3) films compared to HoFeO{sub 3} film. Present study shows electronic excitation induces significant changes in the physical properties of these films. (orig.)

Photoluminescence properties of aeschynite-type LaNbTiO6:RE3+ (RE = Tb, Dy, Ho) down-converting phosphors.

Science.gov (United States)

Ma, Qian; Lu, Mengkai; Yang, Ping; Zhang, Aiyu; Cao, Yongqiang

2014-06-01

In this study, a series of LaNbTiO6:RE(3+) (RE = Tb, Dy, Ho) down-converting phosphors were synthesized using a modified sol-gel combustion method, and their photoluminescence (PL) properties were investigated as a function of activator concentration and annealing temperature. The resultant particles were characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, UV/Vis diffuse reflectance spectroscopy and PL spectra. The highly crystalline LaNbTiO6:RE(3+) (RE = Tb, Dy, Ho) phosphors with an average size of 200-300 nm obtained at 1100°C have an orthorhombic aeschynite-type structure and exhibit the highest luminescent intensity in our study range. The emission spectra of LaNbTiO6:RE(3+) (RE = Tb, Dy, Ho) phosphors under excitations at UV/blue sources are mainly composed of characteristic peaks arising from the f-f transitions of RE(3+), including 489 nm ((5) D4 → (7) F6) and 545 nm ((5) D4 → (7) F5) for Tb(3+), 476 and 482 nm ((4) F9/2 → (6) H15/2) and 571 nm ((4) F9/2 → (6) H13/2) for Dy(3+), and 545 nm ((5) F4 + (5) S2 → (5) I8) for Ho(3+), respectively. The luminescent mechanisms were further investigated. It can be expected that these phosphors are of intense interest and potential importance for many optical applications. Copyright © 2013 John Wiley & Sons, Ltd.

Magnetic and hyperfine interactions in HoFe{sub 1−x}Cr{sub x}O{sub 3} (0≤x≤1) compounds

Energy Technology Data Exchange (ETDEWEB)

Kotnana, Ganesh [Magnetic Materials and Device Physics Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, Hyderabad 502285 (India); Reddy, V. Raghavendra [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001 (India); Jammalamadaka, S. Narayana, E-mail: surya@iith.ac.in [Magnetic Materials and Device Physics Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, Hyderabad 502285 (India)

2017-05-01

We report on the magnetic and Mössbauer properties of polycrystalline HoFe{sub 1-x}Cr{sub x}O{sub 3} (0≤x≤1) compounds. Magnetization data reveals the continuous tailoring of magnetic transition due to weakening of Ho{sup 3+}-Fe{sup 3+} and Fe{sup 3+}-Fe{sup 3+} interactions in the entire temperature range by replacing the Fe{sup 3+} ions with Cr{sup 3+} ions. The observed decrease in Néel temperature (T{sub N}) and increase in spin re-orientation transition temperature (T{sub SR}) with the replacement of Fe{sup 3+} with Cr{sup 3+} is ascribed to the weakening of Fe(Cr)-O-Fe(Cr) antiferromagnetic exchange interaction. In addition, we also attribute such a change in T{sub N} to the enhancement of ferromagnetic interaction of adjacent Cr{sup 3+} moments through t-e hybridization as a result of the structural distortion. The decrease in isomer shift (IS) suggests enhancement of the interaction between nuclear charge with the 3s electrons as a result of decrease in radial part of 3d wave function with Cr addition. In this paper we also discuss about the variation of quadrupole splitting (QS) and hyperfine fields (H{sub hf}) with Cr addition in HoFe{sub 1-x}Cr{sub x}O{sub 3} (0≤x≤1) compounds. - Highlights: • Magnetic and Mössbauer properties of HoFe{sub 1-x}Cr{sub x}O{sub 3} (0≤x≤1) compounds. • T{sub N} changes due to weakening of Ho{sup 3+}-Fe{sup 3+} and Fe{sup 3+}-Fe{sup 3+} interactions with Cr. • The decrease in isomer shift (IS) is due to decrease in radial part of 3d wavefunction. • Octahedral distortion leads to increase in quadrupole splitting.

Absorption and luminescence characteristics of {sup 5}I{sub 7} ↔ {sup 5}I{sub 8} transitions of the holmium ion in Ho{sup 3+}-doped aluminosilicate preforms and fibres

Energy Technology Data Exchange (ETDEWEB)

Ryabochkina, P A; Chabushkin, A N [N.P. Ogarev Mordovian State University, Saransk (Russian Federation); Kosolapov, A F [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Kurkov, A S [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2015-02-28

We have obtained the spectral dependences of the absorption cross sections for the Ho{sup 3+} {sup 5}I{sub 8} → {sup 5}I{sub 6} and {sup 5}I{sub 8} → {sup 5}I{sub 7} transitions in Ho{sup 3+}-doped aluminosilicate fibres and the spectral dependence of the stimulated emission cross section for the Ho{sup 3+} {sup 5}I{sub 7} → {sup 5}I{sub 8} laser transition in Ho{sup 3+}-doped aluminosilicate fibre preforms. The lifetime of the Ho{sup 3+} {sup 5}I{sub 7} upper laser level in the preforms has been determined. (lasers)

The quantitative analysis of 163Ho source by PIXE

International Nuclear Information System (INIS)

Sera, K.; Ishii, K.; Fujioka, M.; Izawa, G.; Omori, T.

1984-01-01

We have been studying the electron-capture in 163 Ho as a method for determining the mass of electron neutrino. The 163 Ho sources were produced with the 164 Dy(p,2n) reaction by means of a method of internal irradiation 2 ). We applied the PIXE method to determine the total number of 163 Ho atoms in the source. Proton beams of 3 MeV and a method of ''external standard'' were employed for nondestructive analysis of the 163 Ho source as well as an additional method of ''internal standard''. (author)

Kundalini Yoga, Yogi Tee und das Wassermannzeitalter: Bibliografische Einblicke in die Healthy, Happy, Holy Organization (3HO) des Yogi Bhajan

OpenAIRE

Laue, Thorsten

2008-01-01

Obwohl seit 40 Jahren im Westen aktiv, ist die Healthy, Happy, Holy Organization (3HO) des Yogi Bhajan (1929-2004) von der deutschen wie internationalen Forschung weitestgehend übersehen worden. Um dieser Forschungslücke entgegenzuwirken, verfasste ich 2003 meine religionswissenschaftlich begründete Magisterarbeit Darstellung und Quellen der 3HO Deutschland e.V. Aus dem Darstellungsteil entstand die 2007 im Münsteraner LIT-Verlag publizierte Monographie Kundalini Yoga, Yogi Tee und das Wasser...

Other Fluoride Products

Science.gov (United States)

... Private Wells Infant Formula Fluorosis Public Health Service Recommendation Water Operators & Engineers Water Fluoridation Additives Shortages of Fluoridation Additives Drinking Water Pipe Systems CDC-Sponsored Water Fluoridation Training Links to Other ...

Preparation of polycrystalline lithium-yttrium fluoride for subsequent mono crystallization

International Nuclear Information System (INIS)

Kowalczyk, E.; Radomski, J.; Diduszko, R.; Iwanejko, J.; Kowalczyk, Z.; Grasza, K.

1994-01-01

High purity lithium-yttrium (YLF) doped with rare earth elements (Nd, Pr, Ho or Tm) was obtained in a two-stage synthesis consisting of (1) reaction of ammonium fluoride with a mixture of lithium carbonate, yttrium oxide, and oxides of lanthanides, and (2) heating of the obtained reaction products at a temperature of about 700 C in an inert gas atmosphere. The phase and chemical purities of the obtained materials were characterized by X-ray diffraction and mass spectrometry techniques. Single crystal growth tests were carried out by means of the Bridgman method. The results showed that the proposed method for manufacture of polycrystalline YLF doped with rare earth elements is appropriate in principle but some parameters of the preparation process are to be more strictly defined. (author). 9 refs, 4 figs, 1 tab

Preparation of polycrystalline lithium-yttrium fluoride for subsequent mono crystallization

Energy Technology Data Exchange (ETDEWEB)

Kowalczyk, E.; Radomski, J.; Diduszko, R.; Iwanejko, J. [Institute of Vacuum Technology, Warsaw (Poland); Kowalczyk, Z. [Warsaw Univ. (Poland); Grasza, K. [Polska Akademia Nauk, Warsaw (Poland). Inst. Fizyki

1994-12-31

High purity lithium-yttrium (YLF) doped with rare earth elements (Nd, Pr, Ho or Tm) was obtained in a two-stage synthesis consisting of (1) reaction of ammonium fluoride with a mixture of lithium carbonate, yttrium oxide, and oxides of lanthanides, and (2) heating of the obtained reaction products at a temperature of about 700 C in an inert gas atmosphere. The phase and chemical purities of the obtained materials were characterized by X-ray diffraction and mass spectrometry techniques. Single crystal growth tests were carried out by means of the Bridgman method. The results showed that the proposed method for manufacture of polycrystalline YLF doped with rare earth elements is appropriate in principle but some parameters of the preparation process are to be more strictly defined. (author). 9 refs, 4 figs, 1 tab.

Spectroscopic analysis of LiHoF4 and LiErF4

DEFF Research Database (Denmark)

Christensen, H.P.

1979-01-01

The polarized absorption spectra for Ho3+ and Er3+ in LiHoF4 and LiErF4, respectively, have been recorded in the spectral interval 4000-26 000 cm-1 at 2 K. Parts of the spectra were examined at higher temperatures. The experimental levels for Ho3+ and Er3+ in LiRF4 were close to those found in Li...

Fluoride-induced disruption of reproductive hormones in men

International Nuclear Information System (INIS)

Ortiz-Perez, Deogracias; Rodriguez-Martinez, Manuel; Martinez, Flavio; Borja-Aburto, V.H.; Castelo, Julio; Grimaldo, J.I.; Cruz, Esperanza de la; Carrizales, Leticia; Diaz-Barriga, Fernando

2003-01-01

Fluoride-induced reproductive effects have been reported in experimental models and in humans. However, these effects were found in heavily exposed scenarios. Therefore, in this work our objective was to study reproductive parameters in a population exposed to fluoride at doses of 3-27 mg/day (high-fluoride-exposed group--HFEG). Urinary fluoride levels, semen parameters, and reproductive hormones in serum (LH, FSH, estradiol, prolactin, inhibin-B, free and total testosterone) were measured. Results were compared with a group of individuals exposed to fluoride at lower doses: 2-13 mg/day (low-fluoride-exposed group-LFEG). A significant increase in FSH (P<0.05) and a reduction of inhibin-B, free testosterone, and prolactin in serum (P<0.05) were noticed in the HFEG. When HFEG was compared to LFEG, a decreased sensitivity was found in the FSH response to inhibin-B (P<0.05). A significant negative partial correlation was observed between urinary fluoride and serum levels of inhibin-B (r=-0.333, P=0.028) in LFEG. Furthermore, a significant partial correlation was observed between a chronic exposure index for fluoride and the serum concentrations of inhibin-B (r=-0.163, P=0.037) in HFEG. No abnormalities were found in the semen parameters studied in the present work, neither in the HFEG, nor in the LFEG. The results obtained indicate that a fluoride exposure of 3-27 mg/day induces a subclinical reproductive effect that can be explained by a fluoride-induced toxic effect in both Sertoli cells and gonadotrophs

[The influence of high fluoride exposure in drinking water on endocrine hormone in female].

Science.gov (United States)

Hou, Jia-xiang; Yang, Yue-jin; Gong, Biao; Li, Shi-hong; Ding, Zhong; Wen, Shi-bao; Li, Shi-qun; Cheng, Xue-min; Cui, Liu-xin; Ba, Yue

2013-02-01

To explore the influence of water fluoride exposure on reproductive hormones in female. Cross-sectional study was conducted in seven villages of a county in Henan province by using simple random sampling including high fluoride area, defluoridation project area and control area on April, 2011 based on the preliminary study results of fluoride concentration in drinking water. Women who were born and growth or lived in the village at least 5 years and aged 18-48 years old were recruited using cluster sampling. They were divided into high fluoride group (HFG, 116 subjects), defluoridation project group (DFPG, 132 subjects) and control group (CG, 227 subjects) in accordance with the above areas. All subjects accepted questionnaire and physical checkup. Fasting blood and morning urine samples were collected. The concentration of fluoride in urine was determined by fluoride ion selective electrode method. The serum level of GnRH was detected using enzyme linked immunosorbent assay (ELISA). The serum level of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), estradiol (E2) were determined by chemiluminesence immunoassay (CLIA). The average age was (39.44 ± 7.34), (38.84 ± 8.03), (37.45 ± 7.70) years old in female from DFPG, HFG and CG respectively, there were no significant differences among the three groups (F = 3.02, P = 0.05). The urine fluoride levels were (1.34 ± 1.07), (2.59 ± 1.57), (0.92 ± 0.46) mg/ml in female from DFPG, HFG and CG respectively, there was a significant difference among three groups (F = 105.38, P 0.05). The serum levels of E2 in Ovulatory period were 67.73, 58.09, 84.96 pg/ml in female from DFPG, HFG and CG respectively. It was lower in HFG than that in CG (H = 4.00, P 0.05). The serum levels of GnRH in Luteal phase were 24.09, 20.16, 23.50 ng/ml in female from DFPG, HFG and CG respectively. It was lower in HFG than that in DFPG (H = 14.14, P 0.05 respectively). The abnormal rates of E2 level were 22.73 (30

Preparation and properties of Y{sub 1-x}Ho{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films by TFA-MOD method

Energy Technology Data Exchange (ETDEWEB)

Jian Hongbin [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Li Qi; Shi Dongqi [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong 2522 (Australia); Zhang Li [Department of Mathematic and Physics, Anhui University of Architecture, Hefei 230022 (China); Yang Zhaorong [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Dou Shixue [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong 2522 (Australia); Zhu Xuebin, E-mail: xbzhu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Sun Yuping [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2011-12-15

Y{sub 1-x}Ho{sub x}BCO thin films were prepared by TFA-MOD. The best performances were obtained for the Y{sub 0.6}Ho{sub 0.4}BCO thin film. The pinning mechanism was {delta}l-type for all derived thin films. Y{sub 1-x}Ho{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) thin films were prepared on LaAlO{sub 3} (0 0 1) substrates by trifluoroacetate metal organic deposition (TFA-MOD) without change of the processing parameters. The highest J{sub c} was attributed to the sample of Y{sub 0.6}Ho{sub 0.4}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} thin film, whose critical current density is about 1.6 times as compared to that of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin film at 77 K and self field. The flux pinning type was not varied with Ho substitution and can be attributed to {delta}l pinning model, which is attributed to the close ionic radius between the Y{sup 3+} and Ho{sup 3+} ions. The improvement of J{sub c} by Ho substitution without change of the processing parameters will provide an effective route to enhance the J{sub c} of YBCO-based thin films using TFA-MOD method.

Phase- and size-controllable synthesis of hexagonal upconversion rare-earth fluoride nanocrystals through an oleic acid/ionic liquid two-phase system.

Science.gov (United States)

He, Meng; Huang, Peng; Zhang, Chunlei; Ma, Jiebing; He, Rong; Cui, Daxiang

2012-05-07

Herein, we introduce a facile, user- and environmentally friendly (n-octanol-induced) oleic acid (OA)/ionic liquid (IL) two-phase system for the phase- and size-controllable synthesis of water-soluble hexagonal rare earth (RE = La, Gd, and Y) fluoride nanocrystals with uniform morphologies (mainly spheres and elongated particles) and small sizes (size are discussed in detail. More importantly, the mechanism of the (n-octanol-induced) OA/IL two-phase system, the formation of the RE fluoride nanocrystals, and the distinctive size- and morphology-controlling capacity of the system are presented. BmimPF(6) is versatile in term of crystal-phase manipulation, size and shape maintenance, and providing water solubility in a one-step reaction. The luminescent properties of Er(3+)-, Ho(3+)-, and Tm(3+)-doped LaF(3), NaGdF(4), and NaYF(4) nanocrystals were also studied. It is worth noting that the as-prepared products can be directly dispersed in water due to the hydrophilic property of Bmim(+) (cationic part of the IL) as a capping agent. This advantageous feature has made the IL-capped products favorable in facile surface modifications, such as the classic Stober method. Finally, the cytotoxicity evaluation of NaYF(4):Yb,Er nanocrystals before and after silica coating was conducted for further biological applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Urinary fluoride excretion in preschool children after intake of fluoridated milk and use of fluoride-containing toothpaste

DEFF Research Database (Denmark)

Norman, M; Twetman, S; Hultgren Talvilahti, A

2017-01-01

Objective: To assess the urinary fluoride excretion in preschool children after drinking fluoridated milk with 0.185 mg F and 0.375 mg F and to study the impact of use of fluoride toothpaste. Basic research design: Double-blind cross-over study. Participants: Nine healthy children, 2.5-4.5 years...

Effects of different amine fluoride concentrations on enamel remineralization.

Science.gov (United States)

Naumova, E A; Niemann, N; Aretz, L; Arnold, W H

2012-09-01

The aim of this study was to investigate the effects of decreasing fluoride concentrations on repeated demineralizing challenges on human enamel. In 24 teeth, 3mm×3mm windows were prepared on the buccal and lingual sides and treated in a cycling demineralization-remineralization model. Remineralization was achieved with 100, 10 and 0.1 ppm fluoride from anime fluoride. Coronal sections were cut through the artificial lesions, and three sections per tooth were investigated using polarized light microscopy and scanning electron microscopy with quantitative element analysis. The morphology of the lesions was studied, and the extensions of the superficial layer and the body of the lesion were measured. Using element analysis, the Ca, P and F content were determined. The body of the lesion appeared remineralized after application of 100 ppm fluoride, while remineralization of the lesion was less successful after application of 10 and 0.1 ppm fluoride. The thickness of the superficial layer increased with decreasing fluoride concentrations, and also the extension of the body of the lesion increased. Ca and P content increased with increasing fluoride concentrations. The effectiveness of fluoride in enamel remineralization increased with increasing fluoride concentration. A consistently higher level of fluoride in saliva should be a goal in caries prevention. Copyright © 2012 Elsevier Ltd. All rights reserved.

[The effect of fluoride-containing tooth paste on dental plaque and on fluoride level in the mouth].

Science.gov (United States)

Oomori, H

1989-01-01

Various kinds of fluoride have been used for a long time and there are many reports concerning fluorides and their effects. Recently, the caries-inhibiting action of fluoride-containing tooth paste has been given much attention. In this study, I tried to clarify the residual time and amount of fluoride derived from the fluoride-containing tooth paste in the mouth, as well as to assess possible variation in bacterial composition in the dental plaque bacteriologically and biochemically. In the study on the fluoride clearance from the mouth, both 1.0 g and 0.5 g of paste showed the same reduction rates; and about an 80% reduction was recognized between the value at 3 minutes and that at 30 minutes, and about a 40% reduction from the 30-minute to the 60-minute interval. Next, a study on the variation in plaque bacteria was carried out. The total number of the CFU on each plate was not different between samples obtained before and after the use of the tooth paste; moreover, no difference was noted between aerobic and anaerobic culture. However, when plaque before and after brushing with fluoride-containing tooth paste were cultured in 10% sucrose solution, the differences of acid production such as lactic acid, acetic acid, and formic acid were demonstrated. Namely, these acid productions were inhibited after the use of fluoride, especially lactic acid was strongly inhibited. On the other hand, when Str. mutans from the plaque obtained after the use of fluoride-containing tooth paste was cultured in fluoride-free BHI broth, the inhibition of acid from carbohydrates was not shown clearly.(ABSTRACT TRUNCATED AT 250 WORDS)

Oral fluoride retention after professional topical application in children with caries activity: comparison between 1.23% fluoride foam and fluoride gel

Directory of Open Access Journals (Sweden)

Cecília Claudia Costa Ribeiro

2008-01-01

Full Text Available Objective: This study evaluated fluoride retention in the saliva of children with caries activity after topical fluoride application in the form of gel and foam. Methods: A cross-sectional, blind and randomized study, conducted with ten caries-active children aged between 8 and 10 years, in two stage, with a washout interval of two weeks between them. The treatments consisted of: a application of 2mL acidulated phosphate fluoride of the gel type in a mold and b application of 2mL acidulated phosphate fluoride of the foam type in a mold. After the washout, the treatments were inverted. Non-stimulated saliva was collected from the children at the times of 5, 15, 30 and 60 minutes after topical fluoride application. For statistical analysis the Student’s-t test was used, with a level of significance of 5%. Results: Saliva analysis was performed using a fluoride-specific electrode (ISE25F/ Radiometer, Copenhagen, Denmark at the Aquatic Science Center of the Federal University of Marana, which revealed differences after 5 minutes (p=0.0055 and 15 minutes (p=0.0208. The topical application of fluoride in the gel form revealed a higher concentration of fluoride in the saliva. Conclusion: There were differences in the retention of fluoride in the saliva of children with caries activity after the topical application of fluoride gel and the topical application of fluoride foam after 5 and 15 minutes of their application. The topical application of fluoride foam is recommended, on the basis of the lower probability of toxicity during its use.

Nanosecond Tm:Y2O3 ceramic laser passively Q-switched by a Ho:LuAG ceramic

Science.gov (United States)

Wang, Hui; Huang, Haitao; Wang, Shiqiang; Shen, Deyuan

2018-02-01

A passively Q-switched 2.05-μm Tm:Y2O3 ceramic laser, employing Ho:LuAG ceramic as a saturable absorber, was demonstrated for the first time. Under the absorbed pump power of 20.5 W, a maximum output power of 497 mW was obtained. Pulses with a minimum pulse width of 642 ns under the repetition rate of 33 kHz were achieved. Our works validate that Ho-doped materials have good potential for passive Q-switching of Tm-doped lasers at 2-μm wavelength region.

Assessment of fluoride in groundwater and urine, and prevalence of fluorosis among school children in Haryana, India

Science.gov (United States)

Haritash, A. K.; Aggarwal, Ankur; Soni, Jigyasa; Sharma, Khyati; Sapra, Mohnish; Singh, Bhupinder

2018-05-01

Considering the health effects of fluoride, the present study was undertaken to assess the concentration of fluoride in groundwater, and urine of school children in Bass region of Haryana state. Fluoride in groundwater was observed to vary from 0.5 to 2.4 mg/l with an average concentration of 0.46 mg/l. On the other hand, F- in urine ranged from below the detection limit to 1.8 mg/l among girls and 0.17-1.2 mg/l among the boys. Higher average concentration of fluoride in urine (0.65 mg/l for boys and 0.34 mg/l for girls) may be ascribed to exposure to bioavailable fluoride through food, milk, tea, toothpaste, etc., in addition to intake through groundwater. Relatively more intake of water and food by the boys might be the reason for more cases of severe dental fluorosis (44%) among boys compared to girls (29% cases of moderate to severe dental fluorosis). The groundwater quality for drinking was compromised with respect to dissolved solids, hardness, magnesium ions, and dissolved iron. Hydro-geochemical investigation revealed that rock-water interaction, in terms of direct cation exchange, dominantly regulates groundwater chemistry, and groundwater is of Ca-Na-HCO3 type.

Eukaryotic resistance to fluoride toxicity mediated by a widespread family of fluoride export proteins.

Science.gov (United States)

Li, Sanshu; Smith, Kathryn D; Davis, Jared H; Gordon, Patricia B; Breaker, Ronald R; Strobel, Scott A

2013-11-19

Fluorine is an abundant element and is toxic to organisms from bacteria to humans, but the mechanisms by which eukaryotes resist fluoride toxicity are unknown. The Escherichia coli gene crcB was recently shown to be regulated by a fluoride-responsive riboswitch, implicating it in fluoride response. There are >8,000 crcB homologs across all domains of life, indicating that it has an important role in biology. Here we demonstrate that eukaryotic homologs [renamed FEX (fluoride exporter)] function in fluoride export. FEX KOs in three eukaryotic model organisms, Neurospora crassa, Saccharomyces cerevisiae, and Candida albicans, are highly sensitized to fluoride (>200-fold) but not to other halides. Some of these KO strains are unable to grow in fluoride concentrations found in tap water. Using the radioactive isotope of fluoride, (18)F, we developed an assay to measure the intracellular fluoride concentration and show that the FEX deletion strains accumulate fluoride in excess of the external concentration, providing direct evidence of FEX function in fluoride efflux. In addition, they are more sensitive to lower pH in the presence of fluoride. These results demonstrate that eukaryotic FEX genes encode a previously unrecognized class of fluoride exporter necessary for survival in standard environmental conditions.

Spectrophotometric determination of fluoride with alizarin complexone

Energy Technology Data Exchange (ETDEWEB)

Marczenko, Z; Lenarczyk, L [Politechnika Warszawska (Poland)

1976-01-01

The modification of direct spectrophotometric method of fluoride determination by alizarin complexone has been developed. It was shown that the lanthanum alizarin complexone chelate is more convenient than that of cerium (3). The influence of acetone, dioxane and dimethyl sulphoxide in water solution on the increase of sensitivity of the method and the rate of colour reaction has been determined. The optimal pH ranges for the reaction with lanthanum and cerium (3) have been estimated. Some amines having a large molecule are useful for extraction of blue fluoride complex with isobutanol. Dioctylamine was applied in a new extraction spectrophotometric procedure of fluoride determination. Conditions in reagent have been established. Both variants of the method have been applied to the fluoride determination in several chemicals. The obtained results show a good precision and accuracy.

Emissions of fluorides from welding processes.

Science.gov (United States)

Szewczyńska, Małgorzata; Pągowska, Emilia; Pyrzyńska, Krystyna

2015-11-01

The levels of fluoride airborne particulates emitted from welding processes were investigated. They were sampled with the patented IOM Sampler, developed by J. H. Vincent and D. Mark at the Institute of Occupational Medicine (IOM), personal inhalable sampler for simultaneous collection of the inhalable and respirable size fractions. Ion chromatography with conductometric detection was used for quantitative analysis. The efficiency of fluoride extraction from the cellulose filter of the IOM sampler was examined using the standard sample of urban air particle matter SRM-1648a. The best results for extraction were obtained when water and the anionic surfactant N-Cetyl-N-N-N-trimethylammonium bromide (CTAB) were used in an ultrasonic bath. The limits of detection and quantification for the whole procedure were 8μg/L and 24μg/L, respectively. The linear range of calibration was 0.01-10mg/L, which corresponds to 0.0001-0.1mg of fluorides per m(3) in collection of a 20L air sample. The concentration of fluorides in the respirable fraction of collected air samples was in the range of 0.20-1.82mg/m(3), while the inhalable fraction contained 0.23-1.96mg/m(3) of fluorides during an eight-hour working day in the welding room. Copyright © 2015. Published by Elsevier B.V.

Arsenic and fluoride removal from groundwater by electrocoagulation using a continuous filter-press reactor.

Science.gov (United States)

Guzmán, Athziri; Nava, José L; Coreño, Oscar; Rodríguez, Israel; Gutiérrez, Silvia

2016-02-01

We investigated simultaneous arsenic and fluoride removal from ground water by electrocoagulation (EC) using aluminum as the sacrificial anode in a continuous filter-press reactor. The groundwater was collected at a depth of 320 m in the Bajío region in Guanajuato Mexico (arsenic 43 µg L(-1), fluoride 2.5 mg L(-1), sulfate 89.6 mg L(-1), phosphate 1.8 mg L(-1), hydrated silica 112.4 mg L(-1), hardness 9.8 mg L(-1), alkalinity 31.3 mg L(-1), pH 7.6 and conductivity 993 µS cm(-1)). EC was performed after arsenite was oxidized to arsenate by addition of 1 mg L(-1) hypochlorite. The EC tests revealed that at current densities of 4, 5 and 6 mA cm(-2) and flow velocities of 0.91 and 1.82 cm s(-1), arsenate was abated and residual fluoride concentration satisfies the WHO standard (CF < 1.5 mg L(-1)). Spectrometric analyses performed on aluminum flocs indicated that these are mainly composed of aluminum-silicates of calcium and magnesium. Arsenate removal by EC involves adsorption on aluminum flocs, while fluoride replaces a hydroxyl group from aluminum aggregates. The best EC was obtained at 4 mA cm(-2) and 1.82 cm s(-1) with electrolytic energy consumption of 0.34 KWh m(-3). Copyright © 2015 Elsevier Ltd. All rights reserved.

No Calcium-Fluoride-Like Deposits Detected in Plaque Shortly after a Sodium Fluoride Mouthrinse

OpenAIRE

Vogel, G.L.; Tenuta, L.M.A.; Schumacher, G.E.; Chow, L.C.

2010-01-01

Plaque ‘calcium-fluoride-like’ (CaF2-like) and fluoride deposits held by biological/bacterial calcium fluoride (Ca-F) bonds appear to be the source of cariostatic concentrations of fluoride in plaque fluid. The aim of this study was to quantify the amounts of plaque fluoride held in these reservoirs after a sodium fluoride rinse. 30 and 60 min after a 228 μg/g fluoride rinse, plaque samples were collected from 11 volunteers. Each sample was homogenized, split into 2 aliquots (aliquots 1 and 2...

Removal of phosphorus, fluoride and metals from a gypsum mining leachate using steel slag filters.

Science.gov (United States)

Claveau-Mallet, Dominique; Wallace, Scott; Comeau, Yves

2013-03-15

The objective of this work was to evaluate the capacity of steel slag filters to treat a gypsum mining leachate containing 11-107 mg P/L ortho-phosphates, 9-37 mg/L fluoride, 0.24-0.83 mg/L manganese, 0.20-3.3 zinc and 1.7-8.2 mg/L aluminum. Column tests fed with reconstituted leachates were conducted for 145-222 days and sampled twice a week. Two types of electric arc furnace (EAF) slags and three filter sequences were tested. The voids hydraulic retention time (HRT(v)) of columns ranged between 4.3 and 19.2 h. Precipitates of contaminants present in columns were sampled and analyzed with X-ray diffraction at the end of tests. The best removal efficiencies over a period of 179 days were obtained with sequential filters that were composed of Fort Smith EAF slag operated at a total HRT(v) of 34 h which removed 99.9% of phosphorus, 85.3% of fluoride, 98.0% of manganese and 99.3% of zinc. Mean concentration at this system's effluent was 0.04 mg P/L ortho-phosphates, 4 mg/L fluoride, 0.02 mg/L manganese, 0.02 zinc and 0.5 mg/L aluminum. Thus, slag filters are promising passive and economical systems for the remediation of mining effluents. Phosphorus was removed by the formation of apatite (hydroxyapatite, Ca(5)(PO(4))(3)OH or fluoroapatite, Ca(5)(PO(4))(3)F) as confirmed by visual and X-ray diffraction analyses. The growth rate of apatite was favored by a high phosphorus concentration. Calcite crystals were present in columns and appeared to be competing for calcium and volume needed for apatite formation. The calcite crystal growth rate was higher than that of apatite crystals. Fluoride was removed by precipitation of fluoroapatite and its removal was favored by a high ratio of phosphorus to fluoride in the wastewater. Copyright © 2012 Elsevier Ltd. All rights reserved.

Hans Werner Richter - Wolfgang Borchert : zwei Schriftsteller im 2. Weltkrieg ; ihre Kriegseinsätze und die Umsetzung in Literatur

OpenAIRE

Brandes, Katrein

2018-01-01

Hans Werner Richter und Wolfgang Borchert, zwei der bekanntesten deutschen Nachkriegsschriftsteller, waren selbst auf erbittert umkämpften Schauplätzen des 2. Weltkrieges eingesetzt: Richter in Italien bei Cassino, Borchert an der Ostfront südlich Moskaus. Trotz der Auseinandersetzung mit ihren literarischen Zeugnissen aus dieser Zeit, wie Richters Roman „Die Geschlagenen“ und Borcherts Kurzgeschichten, ist die Frage nach ihrem eigenen Kriegserleben, nach Schuldbewusstsein und dem Niederschla...

Urinary fluoride output in children following the use of a dual-fluoride varnish formulation

Directory of Open Access Journals (Sweden)

Kelly Polido Kaneshiro Olympio

2009-06-01

Full Text Available OBJECTIVE: This study evaluated the bioavailability of fluoride after topical application of a dual-fluoride varnish commercially available in Brazil, when compared to DuraphatTM. MATERIAL AND METHODS: The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I, children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, sodium fluoride, FGM TM. After 1-month interval (phase II, the same amount (0.2 mL of the fluoride varnish Duraphat (2.26% fluorine, sodium fluoride, ColgateTM was applied. Before each application all the volunteers brushed their teeth with placebo dentifrice for 7 days. Urinary collections were carried out 24 h prior up to 48 h after the applications. Fluoride intake from the diet was also estimated. Fluoride concentration in diet samples and urine was analyzed with the fluoride ion-specific electrode and a miniature calomel reference electrode coupled to a potentiometer. Data were tested by ANOVA and Tukey's post hoc test (p<0.05. RESULTS: There were significant differences in the urinary fluoride output between phases I and II. The use of Duofluorid XII did not significantly increase the urinary fluoride output, when compared to baseline levels. The application of Duraphat caused a transitory increase in the urinary fluoride output, returning to baseline levels 48 h after its use. CONCLUSIONS: The tested varnish formulation, which has been shown to be effective in in vitro studies, also can be considered safe.

Caries arrest by topical fluorides in preschool children: 30-month results.

Science.gov (United States)

Duangthip, D; Wong, M C M; Chu, C H; Lo, E C M

2018-03-01

To compare the effectiveness of three applications of silver diammine fluoride (SDF) solution at yearly interval and three applications of SDF solution or sodium fluoride (NaF) varnish at weekly interval at baseline in arresting active caries in the primary teeth of preschool children. Children aged 3-4 years (n = 371) who had at least one active caries lesion (ICDAS codes 3-6) in their primary teeth were randomly allocated into three groups: Group 1 - annual application of 30% SDF solution; Group 2 - three applications of 30% SDF at weekly intervals; and Group 3 - three applications of 5% NaF varnish at weekly intervals. Follow-up examinations were performed every 6 mo nths by the same masked examiner. After 30 months, 309 (83%) children with 1877 caries lesions remained in the study. For cavitated lesions (ICDAS code 5 or 6), the caries arrest rate of Group 1 (48%) was significantly higher than those of Group 2 (33%) and Group 3 (34%), (p  0.05). Presence of plaque on caries lesion, tooth type and tooth surface type had an influence on caries arrest. Over a 30-month period, annual applications of SDF solution is more effective than three weekly applications of NaF varnish or SDF solution at baseline in arresting active cavitated dentine caries lesions in primary teeth. As annual application of SDF solution was found to be more effective than 3 weekly applications of NaF varnish or SDF solution at baseline in arresting active cavitated dentine caries lesions, the former application protocol is preferred for young children who are available for regular caries arrest treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of the new HNO3-forming channel of the HO2+NO reaction on tropospheric HNO3, NOx, HOx and ozone

Directory of Open Access Journals (Sweden)

A. Kukui

2008-07-01

Full Text Available We have studied the impact of the recently observed reaction NO+HO2→HNO3 on atmospheric chemistry. A pressure and temperature-dependent parameterisation of this minor channel of the NO+HO2→NO2+OH reaction has been included in both a 2-D stratosphere-troposphere model and a 3-D tropospheric chemical transport model (CTM. Significant effects on the nitrogen species and hydroxyl radical concentrations are found throughout the troposphere, with the largest percentage changes occurring in the tropical upper troposphere (UT. Including the reaction leads to a reduction in NOx everywhere in the troposphere, with the largest decrease of 25% in the tropical and Southern Hemisphere UT. The tropical UT also has a corresponding large increase in HNO3 of 25%. OH decreases throughout the troposphere with the largest reduction of over 20% in the tropical UT. The mean global decrease in OH is around 13%, which is very large compared to the impact that typical photochemical revisions have on this modelled quantity. This OH decrease leads to an increase in CH4 lifetime of 5%. Due to the impact of decreased NOx on the OH:HO2 partitioning, modelled HO2 actually increases in the tropical UT on including the new reaction. The impact on tropospheric ozone is a decrease in the range 5 to 12%, with the largest impact in the tropics and Southern Hemisphere. Comparison with observations shows that in the region of largest changes, i.e. the tropical UT, the inclusion of the new reaction tends to degrade the model agreement. Elsewhere the model comparisons are not able to critically assess the impact of including this reaction. Only small changes are calculated in the minor species distributions in the stratosphere.

A model to determine the economic viability of water fluoridation.

Science.gov (United States)

Kroon, Jeroen; van Wyk, Philippus Johannes

2012-01-01

In view of concerns expressed by South African local authorities the aim of this study was to develop a model to determine whether water fluoridation is economically viable to reduce dental caries in South Africa. Microsoft Excel software was used to develop a model to determine economic viability of water fluoridation for 17 water providers from all nine South African provinces. Input variables for this model relate to chemical cost, labor cost, maintenance cost of infrastructure, opportunity cost, and capital depreciation. The following output variables were calculated to evaluate the cost of water fluoridation: per capita cost per year, cost-effectiveness and cost-benefit. In this model it is assumed that the introduction of community water fluoridation can reduce caries prevalence by an additional 15 percent and that the savings in cost of treatment will be equal to the average fee for a two surface restoration. Water providers included in the study serve 53.5 percent of the total population of South Africa. For all providers combined chemical cost contributes 64.5 percent to the total cost, per capita cost per year was $0.36, cost-effectiveness was calculated as $11.41 and cost-benefit of the implementation of water fluoridation was 0.34. This model confirmed that water fluoridation is an economically viable option to prevent dental caries in South African communities, as well as conclusions over the last 10 years that water fluoridation leads to significant cost savings and remains a cost-effective measure for reducing dental caries, even when the caries-preventive effectiveness is modest. © 2012 American Association of Public Health Dentistry.

Isolation of {sup 163}Ho from dysprosium target material by HPLC for neutrino mass measurements

Energy Technology Data Exchange (ETDEWEB)

Mocko, Veronika; Taylor, Wayne A.; Nortier, Francois M.; Engle, Jonathan W.; Pollington, Anthony D.; Kunde, Gerd J.; Rabin, Michael W.; Birnbaum, Eva R. [Los Alamos National Laboratory, Los Alamos, NM (United States). Chemistry Div.; Barnhart, Todd E.; Nickles, Robert J. [Univ. Wisconsinn, Madison, WI (United States). Dept. of Medical Physics

2015-07-01

The rare earth isotope {sup 163}Ho is of interest for neutrino mass measurements. This report describes the isolation of {sup 163}Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, {sup 163}Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm{sup -3} α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized by MC-ICP-MS to determine the {sup 163}Ho/{sup 165}Ho ratio, {sup 163}Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4 x 10{sup 5} for Dy. The isolated Ho fraction contained 24.8 ± 1.3 ng of {sup 163}Ho corresponding to holmium recovery of 72 ± 3%.

High-pressure phase transition in Ho2O3

International Nuclear Information System (INIS)

Lonappan, Dayana; Shekar, N.V. Chandra; Ravindran, T.R.; Sahu, P. Ch.

2010-01-01

High-pressure X-ray diffraction and Raman studies on holmium sesquioxide (Ho 2 O 3 ) have been carried out up to a pressure of ∼17 GPa in a diamond-anvil cell at room temperature. Holmium oxide, which has a cubic or bixbyite structure under ambient conditions, undergoes an irreversible structural phase transition at around 9.5 GPa. The high-pressure phase has been identified to be low symmetry monoclinic type. The two phases coexist to up to about 16 GPa, above which the parent phase disappears. The high-pressure laser-Raman studies have revealed that the prominent Raman band ∼370 cm -1 disappears around the similar transition pressure. The bulk modulus of the parent phase is reported.

The cariostatic mechanisms of fluoride

Directory of Open Access Journals (Sweden)

Kata Rošin-Grget

2013-11-01

Full Text Available This article discusses the possible cariostatic mechanisms of the action of fluoride. In the past, fluoride inhibition of caries was ascribed to reduced solubility of enamel due to incorporation of fluoride (F– into the enamel minerals. The present evidence from clinical and laboratory studies suggests that the caries-preventive mode of action of fluoride is mainly topical. There is convincing evidence that fluoride has a major effect on demineralisation and remineralisation of dental hard tissue. The source of this fluoride could either be fluorapatite (formed due to the incorporation of fluoride into enamel or calcium fluoride (CaF2-like precipitates, which are formed on the enamel and in the plaque after application of topical fluoride. Calcium fluoride deposits are protected from rapid dissolution by a phosphate –protein coating of salivary origin. At lower pH, the coating is lost and an increased dissolution rate of calcium fluoride occurs. The CaF2, therefore, act as an efficient source of free fluoride ions during the cariogenic challenge. The current evidence indicates that fluoride has a direct and indirect effect on bacterial cells, although the in vivo implications of this are still not clear. Conclusion. A better understanding of the mechanisms of the action of fluoride is very important for caries prevention and control. The effectiveness of fluoride as a cariostatic agent depends on the availability of free fluoride in plaque during cariogenic challenge, i.e. during acid production. Thus, a constant supply of low levels of fluoride in biofilm/saliva/dental interference is considered the most beneficial in preventing dental caries.

The cariostatic mechanisms of fluoride.

Science.gov (United States)

Rošin-Grget, Kata; Peroš, Kristina; Sutej, Ivana; Bašić, Krešimir

2013-11-01

This article discusses the possible cariostatic mechanisms of the action of fluoride. In the past, fluoride inhibition of caries was ascribed to reduced solubility of enamel due to incorporation of fluoride (F-) into the enamel minerals. The present evidence from clinical and laboratory studies suggests that the caries-preventive mode of action of fluoride is mainly topical. There is convincing evidence that fluoride has a major effect on demineralisation and remineralisation of dental hard tissue. The source of this fluoride could either be fluorapatite (formed due to the incorporation of fluoride into enamel) or calcium fluoride (CaF2)-like precipitates, which are formed on the enamel and in the plaque after application of topical fluoride. Calcium fluoride deposits are protected from rapid dissolution by a phosphate -protein coating of salivary origin. At lower pH, the coating is lost and an increased dissolution rate of calcium fluoride occurs. The CaF2, therefore, act as an efficient source of free fluoride ions during the cariogenic challenge. The current evidence indicates that fluoride has a direct and indirect effect on bacterial cells, although the in vivo implications of this are still not clear. A better understanding of the mechanisms of the action of fluoride is very important for caries prevention and control. The effectiveness of fluoride as a cariostatic agent depends on the availability of free fluoride in plaque during cariogenic challenge, i.e. during acid production. Thus, a constant supply of low levels of fluoride in biofilm/saliva/dental interference is considered the most beneficial in preventing dental caries. Copyright © 2013 by Academy of Sciences and Arts of Bosnia and Herzegovina.

Protective effect of fluoride varnish and fluoride gel on enamel erosion: roughness, SEM-EDS, and µ-EDXRF studies.

Science.gov (United States)

Soares, Luís Eduardo Silva; De Carvalho Filho, Antonio Carlos Belfort

2015-03-01

The effects of fluoride treatment on bovine enamel subjected to acid erosion were studied by roughness (Ra) measurements, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and microenergy-dispersive X-ray fluorescence spectrometry (μ-EDXRF). Enamel samples (63) were divided into nine groups (n = 7): artificial saliva (AS), Pepsi Twist(®) (PT), orange juice (OJ), Duraphat(®)  + Pepsi Twist(®) (DPH/PT), Duraphat(®)  + orange juice (DPH/OJ), Duofluorid(®)  + Pepsi Twist(®) (DUO/PT), Duofluorid(®)  + orange juice (DUO/OJ), fluoride gel + Pepsi Twist(®) (FG/PT), and fluoride gel + orange juice (FG/OJ). Fluoride was applied and the samples were submitted to six cycles (demineralization: Pepsi Twist(®) or orange juice, 10 min; remineralization: saliva, 1 h). The enamel surface in depth was exposed and 63 line-scan maps were performed. The elemental analysis by EDS revealed that only fluoride treated groups had any detectable fluorine after erosion cycles (DPH/PT: 3.50 wt%; DPH/OJ: 3.37 wt%; DUO/PT: 2.69 wt%; DUO/OJ: 3.54 wt%; FG/PT: 2.17 wt%; FG/OJ: 2.77 wt%). PT treatment resulted in significantly higher Ra values than the artificial saliva (P < 0.001). Scanning electron microscopy (SEM) analysis of fluoride protected enamel showed areas with some globular structures or a residual layer of varnish. The enamel thickness was significantly lower in PT (0.63 ± 0.087 mm) than in DPH/PT (0.87 ± 0.16 mm) and DUO/PT (0.92 ± 0.14 mm) groups (P < 0.01). Fluoride treatments protected enamel without Ra increase and loss of enamel tissue. © 2015 Wiley Periodicals, Inc.

Fluoride content and labelling of toothpastes marketed in India.

Science.gov (United States)

Thakkar, V P; Rao, A; Rajesh, G; Shenoy, R; Pai, M

2015-09-01

To enumerate the fluoride content and labelling practices of toothpastes marketed in India and to determine if the content is in accordance with the information provided on the packaging. In vitro analysis of total and free available fluoride in 5 adult and 5 children's fluoride toothpastes in India using fluoride ion electrode. Information on the tube and carton was checked to assess the labelling. The mean Total Fluoride concentrations (TF) in the toothpastes labelled 1,000 ppm, 500ppm and 458 ppm were 1,000, 500 and 449mg/L (sd values 3, 5 and 4mg/L) respectively. The toothpastes' Total Soluble Fluoride (TSF) concentration was generally slightly less than the TF concentration. Overall mean percentage of TSF concentration was 94% sd 9%. The mean percentage of TSF concentration in SMFP (sodium monofluorophosphate)/CaCO3 (calcium carbonate) containing toothpastes was 86% sd 16% while that in NaF (sodium fluoride)/Si (silica) based toothpastes was 98% sd 1% and 95% sd 1% in the remaining toothpastes with unknown abrasive. NaF/Si based toothpastes had more TSF concentration than the others (plabelled following the guidelines of the regulatory body of India, 3 of the 10 failed to mention the abrasive present.

Laser excited fluorescence spectrum of Ho3+:SrF2 single crystal

International Nuclear Information System (INIS)

Lal, Bansi; Ramachandra Rao, D.

1980-01-01

The fluorescence spectrum of Ho 3+ : SrF 2 single crystal excited by the various lines of an Ar + laser, is reported. The three fluorescence groups recorded in the region 5300-7700 A, correspond to the transitions from ( 5 F 4 , 5 S 2 ) to 5 I 8 , 5 F 5 to 5 I 8 , 5 F 3 to 5 I 7 and ( 5 F 4 , 5 S 2 ) to 5 I 7 . Marked changes in the total integrated intensity of the various fluorescence groups with the change in the exciting wavelength are observed. (author)

Fluoride and Oral Health.

Science.gov (United States)

O'Mullane, D M; Baez, R J; Jones, S; Lennon, M A; Petersen, P E; Rugg-Gunn, A J; Whelton, H; Whitford, G M

2016-06-01

The discovery during the first half of the 20th century of the link between natural fluoride, adjusted fluoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fluoride in improving oral health. Epidemiological studies of fluoridation programmes have confirmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fluoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fluoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fluorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fields of knowledge required to successfully implement complex interventions such as the use of fluorides to improve dental and oral health. Financial support for research into the development of these new fluoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fluoride vehicles and strategies is noteworthy. This updated version of 'Fluoride and Oral Health' has adopted an evidence-based approach to its commentary on the different fluoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature.

FAGE measurements of tropospheric HO with measurements and model of interferences

Science.gov (United States)

Hard, T. M.; Mehrabzadeh, A. A.; Chan, C. Y.; O'Brien, R. J.

1992-01-01

Ambient HO measurements by low-pressure laser-excited fluorescence with chemical modulation, and supporting ozone and water-vapor data, are presented for periods in May and August 1987. The observed peak daytime ambient HO concentrations are in the range (2.5 to 8) x 10 exp 6 molecules/cu cm and show small negative offsets due to photochemical interference. Direct measurements of the interference at fixed (O3) give the dependence on ambient (H2O) and on the modulating reagent (isobutane). At ambient (O3) = 30 ppb and 10 torr H2O, with excitation and detection at a total pressure of 4 torr, the net interference is equal to (HO) = -1.3 x 10 exp 6 molecules/cu cm. Production of HO by the reaction of isobutane with O(1D) accounts for the negative interference. Quenching of HO fluorescence by the modulating reagent contributes a smaller positive term to the interference; kinetic measurements of the quenching rate coefficient are reported. The experimental interference results are compared with a detailed kinetic model of HO production, excitation, relaxation, and detection; reasonable agreement is found.

Fluoride level in saliva after bonding orthodontic brackets with a fluoride containing adhesive

NARCIS (Netherlands)

Ogaard, B; Arends, J; Helseth, H; Dijkman, G; vanderKuijl, M

The fluoride level in saliva is considered an important parameter in caries prevention. Elevation of the salivary fluoride level by a fluoride-releasing orthodontic bonding adhesive would most likely be beneficial in the prevention of enamel caries. In this study, the fluoride level in saliva was

The effects of fluoride, strontium, theobromine and their combinations on caries lesion rehardening and fluoridation.

Science.gov (United States)

Lippert, Frank

2017-08-01

The aim was to investigate the effects of fluoride, strontium, theobromine and their combinations on caries lesion rehardening and fluoridation (EFU) under pH cycling conditions. Human enamel specimens were demineralized at 37°C for 24h using a pH 5.0 solution containing 50mM lactic acid and 0.2% Carbopol 907 which was 50% saturated with respect to hydroxyapatite. Lesions were assigned to nine treatment groups (n=16) based on Knoop surface microhardness indentation length. aqueous solutions were: placebo, 11.9mM sodium fluoride (F), 23.8mM sodium fluoride (2×F), 1.1mM strontium chloride hexahydrate (Sr), 1.1mM F theobromine, Sr+theobromine, F+Sr, F+theobromine, F+Sr+theobromine. Lesions were pH cycled for 5d (daily protocol: 3×1min-treatment; 2×60min-demineralization; 4×60min & overnight-artificial saliva). Knoop indentation length was measured again and%surface microhardness recovery (%SMHr) calculated. EFU was determined using the acid-etch technique. Data were analysed using ANOVA. Model showed fluoride dose-response for both variables (2×F>F>placebo). For%SMHr, F+Sr+/-theobromine resulted in more rehardening than F, however less than 2×F. F+theobromine was similar to F. For EFU, F+Sr was inferior to F, F+theobromine and F+Sr+theobromine which were similar and inferior to 2×F. In absence of fluoride, Sr, theobromine or Sr+theobromine were virtually indistinguishable from placebo and inferior to F. It can be concluded that a) strontium aids rehardening but not EFU and only in presence of fluoride; b) theobromine does not appear to offer any anti-caries benefits in this model; c) there are no synergistic effects between strontium and theobromine in the presence or absence of fluoride. Copyright © 2017 Elsevier Ltd. All rights reserved.

Návrh ubytovacího rezervačního internetového portálu

OpenAIRE

Čurilla, Miroslav

2010-01-01

Táto diplomová práca sa zaoberá návrhom ubytovacieho rezervačného internetového portálu. Cieľom práce je navrhnutie systému rezervovania ubytovania v ubytovacích zariadenia optimálnym spôsobom. Vedľajšími cieľmi je navrhnutie hardvérových, softvérových, bezpečnostných, marketingových a ekonomických riešení pri návrhu ubytovacieho rezervačné internetového portálu. This master’s thesis deals with the design of the internet portal for the reservation of accommodation. Its objective is the pro...

Spatial distribution mapping of drinking water fluoride levels in Karnataka, India: fluoride-related health effects.

Science.gov (United States)

Chowdhury, Chitta R; Shahnawaz, Khijmatgar; Kumari, Divya; Chowdhury, Avidyuti; Bedi, Raman; Lynch, Edward; Harding, Stewart; Grootveld, Martin

2016-11-01

(1) To estimate the concentrations of fluoride in drinking water throughout different zones and districts of the state of Karnataka. (2) To investigate the variation of fluoride concentration in drinking water from different sources, and its relationships to daily temperature and rainfall status in the regional districts. (3) To develop an updated fluoride concentration intensity map of the state of Karnataka, and to evaluate these data in the context of fluoride-related health effects such as fluorosis and their prevalence. Aqueous standard solutions of 10, 100 and 1,000 ppm fluoride (F - ) were prepared with analytical grade Na + /F - and a buffer; TISAB II was incorporated in both calibration standard and analysis solutions in order to remove the potentially interfering effects of trace metal ions. This analysis was performed using an ion-selective electrode (ISE), and mean determination readings for n = 5 samples collected at each Karnataka water source were recorded. The F - concentration in drinking water in Karnataka state was found to vary substantially, with the highest mean values recorded being in the north-eastern zone (1.61 ppm), and the lowest in the south-western one (only 0.41 ppm). Analysis of variance (ANOVA) demonstrated that there were very highly significant 'between-zone' and 'between-districts-within-zones' sources of variation (p water source F - levels within this state. The southern part of Karnataka has low levels of F - in its drinking water, and may require fluoridation treatment in order to mitigate for dental caries and further ailments related to fluoride deficiency. However, districts within the north-eastern region have contrastingly high levels of fluoride, an observation which has been linked to dental and skeletal fluorosis. This highlights a major requirement for interventional actions in order to ensure maintenance of the recommended range of fluoride concentrations (0.8-1.5 ppm) in Karnataka's drinking water

Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

Directory of Open Access Journals (Sweden)

Timothy A. DeVol

2010-03-01

Full Text Available This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminescent properties. We discuss the synthesis, properties, and application of heavy metal fluorides; specifically LaF3:RE and PbF2, and group IIA fluorides. Particular attention is given to the synthesis of core/shell nanoparticles, including selectively RE-doped LaF3/LaF3, and CaF2/CaF2 core/(multi-shell nanoparticles, and the CaF2-LaF3 system.

[Monograph for 3-(4-methylbenzylidene)camphor (4-MBC)--HBM values for the sum of metabolites 3-(4-carboxybenzylidene)camphor (3-4CBC) and 3-(4-carboxybenzylidene)-6-hydroxycamphor (3-4 CBHC) in the urine of adults and children. Statement of the HBM Commission of the German Federal Environment Agency].

Science.gov (United States)

2016-01-01

The substance 3-(4-methylbenzylidene)camphor (4-MBC, CAS-No. 36861-47-9 as well as 38102-62-4) is used as UV-filter in cosmetics, mainly in sunscreen lotions. National as well as European evaluations are available for the substance, especially from the Scientific Committee on Consumer Products (SCCP). The SCCP did not derive a TDI-value, but used for a MoS assessment a NOAEL of 25 mg/(kg bw · d) based on effects on the thyroid gland of rats in a subchronic study with oral administration. Newer studies, however, indicate lower NOAEL values, leading to tolerable daily intakes of 0,01 mg/kg bw. The HBM Commission established for the metabolite 3-(4-carboxybenzylidene)camphor (3-4CBC) HBM-I values of 0,09 mg/l urine for adults and 0,06 mg/l urine for children. HBM-I values for the metabolite 3-(4-carboxybenzylidene)-6-hydroxycamphor (3-4CBHC) were set at 0,38 mg/l urine for adults and 0,25 mg/l urine for children. The rounded HBM-I value for the sum of metabolites 3-4CBC und 3-4CBHC is accordingly 0,5 mg/l urine for adults and 0,3 mg/l urine for children.

Sirt1 overexpression suppresses fluoride-induced p53 acetylation to alleviate fluoride toxicity in ameloblasts responsible for enamel formation.

Science.gov (United States)

Suzuki, Maiko; Ikeda, Atsushi; Bartlett, John D

2018-03-01

Low-dose fluoride is an effective caries prophylactic, but high-dose fluoride is an environmental health hazard that causes skeletal and dental fluorosis. Treatments to prevent fluorosis and the molecular pathways responsive to fluoride exposure remain to be elucidated. Previously we showed that fluoride activates SIRT1 as an adaptive response to protect cells. Here, we demonstrate that fluoride induced p53 acetylation (Ac-p53) [Lys379], which is a SIRT1 deacetylation target, in ameloblast-derived LS8 cells in vitro and in enamel organ in vivo. Here we assessed SIRT1 function on fluoride-induced Ac-p53 formation using CRISPR/Cas9-mediated Sirt1 knockout (LS8 Sirt/KO ) cells or CRISPR/dCas9/SAM-mediated Sirt1 overexpressing (LS8 Sirt1/over ) cells. NaF (5 mM) induced Ac-p53 formation and increased cell cycle arrest via Cdkn1a/p21 expression in Wild-type (WT) cells. However, fluoride-induced Ac-p53 was suppressed by the SIRT1 activator resveratrol (50 µM). Without fluoride, Ac-p53 persisted in LS8 Sirt/KO cells, whereas it decreased in LS8 Sirt1/over . Fluoride-induced Ac-p53 formation was also suppressed in LS8 Sirt1/over cells. Compared to WT cells, fluoride-induced Cdkn1a/p21 expression was elevated in LS8 Sirt/KO and these cells were more susceptible to fluoride-induced growth inhibition. In contrast, LS8 Sirt1/over cells were significantly more resistant. In addition, fluoride-induced cytochrome-c release and caspase-3 activation were suppressed in LS8 Sirt1/over cells. Fluoride induced expression of the DNA double strand break marker γH2AX in WT cells and this was augmented in LS8 Sirt1/KO cells, but was attenuated in LS8 Sirt1/over cells. Our results suggest that SIRT1 deacetylates Ac-p53 to mitigate fluoride-induced cell growth inhibition, mitochondrial damage, DNA damage and apoptosis. This is the first report implicating Ac-p53 in fluoride toxicity.

Electric-field gradients at {sup 181}Ta impurity sites in Ho{sub 2}O{sub 3} and Eu{sub 2}O{sub 3} bixbyites

Energy Technology Data Exchange (ETDEWEB)

Errico, Leonardo A. [Departamento de Fisica-IFLP(CONICET), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Renteria, Mario [Departamento de Fisica-IFLP(CONICET), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina)]. E-mail: renteria@fisica.unlp.edu.ar; Bibiloni, Anibal G. [Departamento de Fisica-CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Freitag, Kristian [Helmholtz-Institut fuer Strahlen-und Kernphysik (H-ISKP) der Universitaet Bonn, Nussallee 14-16, D 53115 Bonn (Germany)

2007-02-01

The time-differential {gamma}-{gamma} perturbed-angular-correlation (PAC) technique with ion-implanted {sup 181}Hf tracers has been applied to study the hyperfine interactions of {sup 181}Ta impurities in the cubic bixbyite structure of Ho{sub 2}O{sub 3} and Eu{sub 2}O{sub 3}. The PAC experiments were performed in air in the temperature range 300-1373 K (in the case of Ho{sub 2}O{sub 3}) and 77-1273 K (in the case of Eu{sub 2}O{sub 3}). For both oxides, two electric-quadrupole interactions were found and attributed to the electric-field gradients (EFGs) acting on {sup 181}Ta probes substitutionally located at the two free-of-defects nonequivalent cation sites of the bixbyite structure. In the case of Ho{sub 2}O{sub 3}, two additional interactions were found in the temperature range 300-573 K. These results, as well as previous characterizations of the EFG at {sup 181}Ta sites in bixbyites, were compared to those obtained in experiments using {sup 111}Cd as probe, and to point-charge model calculations. Very recent ab initio predictions for the EFG tensor at impurities sites in binary oxides are also discussed. All these results enable us to discuss the validity of the widely used ionic model to describe the EFG in these highly ionic compounds.

Photosynthesis of ammonium uranous fluoride

International Nuclear Information System (INIS)

El-Fekey, S.A.; Zaki, M.R.; Farah, M.Y.

1975-01-01

This study pertains to utilisation of solar energy for ethanol photosynthesis of ammonium uranous fluoride, that satisfies nuclear specifications needed for calcio- or magnesiothermy. Insolation in autumn using 4-10% ethanol in 5-20 g uranium/litre at initial pH 3.25 gave practically 99.8% yield in two hours, independant of 1.0 to 2.0 stoichiometric NH 4 F. With ultraviolet light, the yield varied between 30 and 60%, even after four hours irradiation. Stirring and heating to 60 0 C raised the tap density of the dried double fluorides from 1.48 at 30 0 C, to 1.85 g/cm 3 at 60 0 C. The texture increased also in fineness to 100% 50μ aggregates. The powders satisfy nuclear purity specifications. Thermograms indicated preferential decomposition of double fluoride at 375 0 C in controlled atmosphere to obtain nuclear pure anhydrous uranium tetrafluoride

Experimental Investigation of Phase Equilibria in the Ho-Ti-Si Ternary System at 973 K (700 °C)

Science.gov (United States)

Han, Feng; Zhan, Yongzhong

2018-02-01

Phase equilibrium relations of the Ho-Ti-Si ternary system at 973 K (700 °C) were experimentally researched by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometer (EDS). The isothermal section of the system at 973 K (700 °C) consists of 14 three-phase regions, 27 two-phase regions, and 14 single-phase regions. The phases Ti5Si3, Ti5Si4, TiSi, TiSi2, Ho5Si3, Ho5Si4, HoSi, αHoSi2-b, and βHoSi2-a are proved to exist at 973 K (700 °C). Previously reported HoTiSi and Ho2Ti3Si4 ternary compounds were confirmed to exist at this temperature. The solubility of Ho in the intermediate phases (i.e., TiSi2, TiSi, Ti5Si4, and Ti5Si3) at the Ti-Si side is extremely small. The maximum solubilities of Ti in HoSi2-b, Ho5Si4, and Ho5Si3 are confirmed to be 8.0, 7.2, and 6.0 at. pct, respectively.

Synthesis, structural characterization and fluctuation conductivity of HoBa2Cu3O7-δ-SrTiO3 composites

International Nuclear Information System (INIS)

Uribe Laverde, M.A.; Landinez Tellez, D.A.; Roa-Rojas, J.

2010-01-01

Single-phase polycrystalline samples of HoBa 2 Cu 3 O 7-δ superconductor and SrTiO 3 isolator were produced by means of the solid state reaction technique. After structural characterization of both materials, superconductor-isolator composites were produced with nominal isolator volume percentages between 0% and 10%. Resistivity measurements for the composites and the HoBa 2 Cu 3 O 7-δ sample with different currents evidenced a superconducting transition with critical temperature T C = 92 K, with wider transitions with increasing either isolator content or measurement current. Fluctuation conductivity analyses were carried out to obtain the exponents characterizing the conductivity divergence. Above T C , apart from the typical Gaussian and critical fluctuations an atypical regime with critical exponent about 0.14 is observed as a precursor of the transition. Below T C , it is observed that the coherence transition characteristic exponent increases rapidly with increasing isolator percentage in the composites and does not show important changes when modifying the current in the pure superconductor sample.

Optical spectroscopy of Ho{sup 3+}-doped SrWO{sub 4} scheelite crystal

Energy Technology Data Exchange (ETDEWEB)

Li Jianfu; Jia Guohua; Zhu Zhaojie; You Zhenyu; Wang Yan; Wu Baichang; Tu Chaoyang [Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, State Key Laboratory of Structural Chemistry and National Engineering Research Center for Optoelectronic Crystalline Materials, Fuzhou, Fujian 350002 (China)

2007-04-07

Ho{sup 3+}-doped SrWO{sub 4} crystal was grown by the Czochralski method. The polarized absorption and emission spectra together with the fluorescent decay curve were measured at room temperature. The intensity parameters, radiative lifetimes and branching ratios were calculated based on the Judd-Ofelt theory. The stimulated emission cross-sections of the potential laser transitions were determined using the reciprocity method.

Spectroscopic characterization and temporal dynamics of energy transfer process between Tm{sup 3+} -Ho{sup 3+} and Yb{sup 3+} -Tm{sup 3+} ions in LiYF{sub 4} and LiLuF{sub 4} crystals; Caracterizacao espectroscopica e dinamica temporal dos processos de transferencia de energia entre os ions Tm{sup 3+} -Ho{sup 3+} e Yb{sup 3+} -Tm{sup 3+} em cristais de LiYF{sub 4} and LiLuF{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Tarelho, Luiz Vicente Gomes

2001-07-01

In this work, we perform spectroscopic studies to characterize the energy transfer processes occurring in rare-earth doped lithium fluoride systems, aiming the optimization of the population inversion of these media. Yb{sup 3+} ion was used in order to probe the electron-phonon coupling in LiYF{sub 4}, LiGdF{sub 4} and LiLuF{sub 4} matrices. In these systems it was obtained the average phononenergy, the vibronic transition probability and Huang-Rhys coupling constant. These parameters are dependent on the crystal host and the LiLuF{sub 4} system presents excluded correlation effects, an electronic repulsion that weakens the vibronic coupling. The Tm:Ho:LiYF{sub 4} system was studied under diode laser pumping at 796 nm, aiming the 2 {mu}m emission optimization. The ideal conditions of concentration and laser power were determined favouring the latter emission. Upconversion processes of two photons were identified besides the energy transfer among ions. The dynamic processes of luminescence of donors and acceptors allowed one to classify the energy transfer process as an energy transfer process assisted by fast diffusion among donors. The spectroscopic study of the Yb:Tm:LiYF{sub 4} allowed the determination of efficient non resonant transfer mechanisms between ({sup 2}F{sub 5/2}) Ytterbium level and ({sup 3}H{sub 5}) Thulium level, assisted by two phonon with hopping migration among donors ( Foerster-Burshtein model). The repopulation process of the Yb donor level is due to a cooperative sensitization between Yb-Tm pairs followed by an energy transfer process. (author)

29 CFR 34.3 - Discrimination prohibited.

Science.gov (United States)

2010-07-01

... 29 Labor 1 2010-07-01 2010-07-01 true Discrimination prohibited. 34.3 Section 34.3 Labor Office of... THE JOB TRAINING PARTNERSHIP ACT OF 1982, AS AMENDED (JTPA) General Provisions § 34.3 Discrimination... participation in JTPA, be excluded from participation in, denied the benefits of, subjected to discrimination...

Single-Mode, High Repetition Rate, Compact Ho:YLF Laser for Space-Borne Lidar Applications

Science.gov (United States)

Bai, Yingxin; Yu, Jirong; Wong, Teh-Hwa; Chen, Songsheng; Petros, Mulugeta; Singh, Upendra N.

2014-01-01

A single transverse/longitudinal mode, compact Q-switched Ho:YLF laser has been designed and demonstrated for space-borne lidar applications. The pulse energy is between 34-40 mJ for 100-200 Hz operation. The corresponding peak power is >1 MW.

Fluoride glass fiber optics

CERN Document Server

Aggarwal, Ishwar D

1991-01-01

Fluoride Glass Fiber Optics reviews the fundamental aspects of fluoride glasses. This book is divided into nine chapters. Chapter 1 discusses the wide range of fluoride glasses with an emphasis on fluorozirconate-based compositions. The structure of simple fluoride systems, such as BaF2 binary glass is elaborated in Chapter 2. The third chapter covers the intrinsic transparency of fluoride glasses from the UV to the IR, with particular emphasis on the multiphonon edge and electronic edge. The next three chapters are devoted to ultra-low loss optical fibers, reviewing methods for purifying and

A simple and colorimetric fluoride receptor and its fluoride-responsive organogel

Energy Technology Data Exchange (ETDEWEB)

Yu Xudong, E-mail: 081022009@fudan.edu.cn [College of Science, Hebei University of Science and Technology, Yuhua Road 70, Shijiazhuang 050080 (China); Li Yajuan [College of Science, Hebei University of Science and Technology, Yuhua Road 70, Shijiazhuang 050080 (China); Yin Yaobing; Yu Decai [College of Science, Hebei University of Engineering, 199 South street of Guangming, Handan 056038 (China)

2012-08-01

In this paper, a new p-nitrophenylhydrozine-based anion receptor 1 containing cholesterol group had been designed and synthesized. It could selectively recognize fluoride among different anions tested with color changes from pale yellow to red for visual detection. Simultaneously, it could gel in cyclohexane, and the gel was also fluoride-responsive. When treated with TBAF (tetra-n-butylammonium fluoride), the gel could undergo gel-sol transition accompanied by color, morphology and surface changes. The binding mechanism had been investigated by UV-vis and {sup 1}HNMR (proton nuclear magnetic resonance spectra) titrations. From SEM (scanning electron microscope), SAXS (small-angle X-ray scattering), IR (Infrared Spectroscopy) and CA (contact angle) experiments, it was indicated that the addition of F{sup -} could destroy the molecule assembly of host 1 in the gel state, thus resulting in the gel-to-sol transition due to the binding site competition effect. To the best of our knowledge, this was the simplest fluoride-responsive organogel with high selectivity. Highlights: Black-Right-Pointing-Pointer A novel kind receptor for selective recognition of fluoride had been designed. Black-Right-Pointing-Pointer Its organogel was also fluoride-responsive. Black-Right-Pointing-Pointer This is the simplest fluoride-responsive organogel with high selectivity.

Biochemical studies on the effect of fluoride on higher plants. 3. The effect of fluoride on dark carbon dioxide fixation

Energy Technology Data Exchange (ETDEWEB)

Yang, S F; Miller, G W

1963-01-01

Dark CO/sub 2/ fixation and phosphoenolpyruvate-carboxylase activity were studied in fluoride-necrotic and control soya-bean leaves. Necrotic leaves had a higher rate of dark CO/sub 2/ fixation than control leaves both in vivo and in vitro (phosphoenolpyruvate carboxylase). Results suggested that the accumulation of organic acids and amino acids in necrotic leaves resulted from an increased rate of dark CO/sub 2/ fixation. The possible role of fluoride in stimulating the carboxylation and its implication to necrosis are discussed.

Fluoride metabolism in plants

Energy Technology Data Exchange (ETDEWEB)

Peters, R; Shorthouse, M

1964-04-04

Grass seedlings exposed to inorganic fluoride solutions do not take up appreciable amounts of fluoride until concentrations of more than 1.0 mM (19 p.p.m.) are used. No formation of organic fluoride has been found, even with exposure to 15.75 mM fluoride, indicating that there is no formation of fluoroacetate or similar compounds. 8 references, 2 tables.

Solvothermal indium fluoride chemistry: Syntheses and crystal structures of K5In3F14, β-(NH4)3InF6 and [NH4]3[C6H21N4]2[In4F21

International Nuclear Information System (INIS)

Jayasundera, Anil C.A.; Goff, Richard J.; Li Yang; Finch, Adrian A.; Lightfoot, Philip

2010-01-01

The solvothermal syntheses and crystal structures of three indium fluorides are presented. K 5 In 3 F 14 (1) and β-(NH 4 ) 3 InF 6 (2) are variants on known inorganic structure types chiolite and cryolite, respectively, with the latter exhibiting a complex and apparently novel structural distortion. [NH 4 ] 3 [C 6 H 21 N 4 ] 2 [In 4 F 21 ] (3) represents a new hybrid composition displaying a unique trimeric metal fluoride building unit. - Graphical abstract: Solvothermal synthesis has been used to prepare three indium fluorides, including a novel hybrid material containing a unique [In 3 F 15 ] trimer templated by tren.

Bottled Water and Fluoride

Science.gov (United States)

... Private Wells Infant Formula Fluorosis Public Health Service Recommendation Water Operators & Engineers Water Fluoridation Additives Shortages of Fluoridation Additives Drinking Water Pipe Systems CDC-Sponsored Water Fluoridation Training Links to Other ...

Does acetone react with HO2 in the upper-troposphere?

Directory of Open Access Journals (Sweden)

J. Lelieveld

2012-02-01

Full Text Available Recent theoretical calculations showed that reaction with HO2 could be an important sink for acetone (CH3C(OCH3 and source of acetic acid (CH3C(OOH in cold parts of the atmosphere (e.g. the tropopause region. This work details studies of HO2 + CH3C(OCH3 (CH32C(OHOO (R1 in laboratory-based and theoretical chemistry experiments; the atmospheric significance of Reaction (R1 was assessed in a global 3-D chemical model. Pulsed laser-kinetic experiments were conducted, for the first time, at the low-temperatures representative of the tropopause. Reaction with NO converted HO2 to OH for detection by laser induced fluorescence. Reduced yields of OH at T 2 by CH3C(OCH3 with a forward rate coefficient greater than 2 × 10−12 cm3 molecule−1 s−1. No evidence for Reaction (R1 was observed at T > 230 K, probably due to rapid thermal dissociation back to HO2 + CH3C(OCH3. Numerical simulations of the data indicate that these experiments were sensitive to only (R1a HO2-CH3C(OCH3 complex formation, the first step in (R1. Rearrangement (R1b of the complex to form peroxy radicals, and hence the atmospheric significance of (R1 has yet to be rigorously verified by experiment. Results from new quantum chemical calculations indicate that K1 is characterised by large uncertainties of at least an order of magnitude at T 3C(OCH3 near the tropopause, it cannot explain observations of CH3C(OOH throughout the troposphere.

Observations of OH and HO2 radicals in coastal Antarctica

Directory of Open Access Journals (Sweden)

S. J.-B. Bauguitte

2007-08-01

Full Text Available OH and HO2 radical concentrations have been measured in the boundary layer of coastal Antarctica for a six-week period during the austral summer of 2005. The measurements were performed at the British Antarctic Survey's Halley Research Station (75° 35' S, 26° 19' W, using the technique of on-resonance laser-induced fluorescence to detect OH, with HO2 measured following chemical conversion through addition of NO. The mean radical levels were 3.9×105 molecule cm−3 for OH, and 0.76 ppt for HO2 (ppt denotes parts per trillion, by volume. Typical maximum (local noontime levels were 7.9×105 molecule cm−3 and 1.50 ppt for OH and HO2 respectively. The main sources of HOx were photolysis of O3 and HCHO, with potentially important but uncertain contributions from HONO and higher aldehydes. Of the measured OH sinks, reaction with CO and CH4 dominated, however comparison of the observed OH concentrations with those calculated via the steady state approximation indicated that additional co-reactants were likely to have been present. Elevated levels of NOx resulting from snowpack photochemistry contributed to HOx cycling and enhanced levels of OH, however the halogen oxides IO and BrO dominated the CH3O2 – HO2 – OH conversion in this environment, with associated ozone destruction.

Line Identification of Atomic and Ionic Spectra of Holmium in the Near-UV. Part I. Spectrum of Ho i

Energy Technology Data Exchange (ETDEWEB)

Al-Labady, N.; Özdalgiç, B. [Graduate School of Engineering and Sciences, Istanbul University, TR-34452 Beyazıt, Istanbul (Turkey); Er, A.; Güzelçimen, F.; Öztürk, I. K.; Başar, Gö. [Faculty of Science, Department of Physics, Istanbul University, TR-34134 Vezneciler, Istanbul (Turkey); Kröger, S. [Hochschule für Technik und Wirtschaft Berlin, Wilhelminenhofstr. 75A, D-12459 Berlin (Germany); Kruzins, A.; Tamanis, M.; Ferber, R., E-mail: ikanat@istanbul.edu.tr [Laser Centre, The University of Latvia, Rainis Boulevard 19, LV-1586 Riga (Latvia)

2017-02-01

The Fourier Transform spectra of a Holmium hollow cathode discharge lamp have been investigated in the UV spectral range from 25,000 up to 31,530 cm{sup −1} (317 to 400 nm). Two Ho spectra have been measured with neon and argon as buffer gases. Based on the intensity ratios from these two spectra, a distinction was made between atomic and ionic lines (ionic lines are discussed in an accompanying paper). Using the known Ho i energy levels, 71 lines could be classified as transitions of atomic Ho, 34 of which have not been published previously. Another 32 lines, which could not be classified, are listed in the literature and assigned as atomic Ho. An additional 370 spectral lines have been assigned to atomic Ho based on the signal-to-noise ratio in the two spectra measured under different discharge conditions, namely with buffer gases argon and neon, respectively. These 370 lines have not been previously listed in the literature.

Výložník kombinovaného skládkového stroje

OpenAIRE

Štursa, Martin

2013-01-01

Tato diplomová práce se zabývá konstrukcí částí kombinovaného skládkového stroje určeného pro obsluhu skládky hnědého uhlí u uhelné elektrárny. Nejprve jsou nadefinovány základní parametry stroje a silové účinky zatěžující stroj během provozu. Práce dále obsahuje návrh ocelové konstrukce kolesového výložníku, kolesa, korečků, pohonu kolesa, hřídele, ložisek a dalších částí kolesového výložníku. Tyto součásti jsou ověřeny analytickými nebo konečnoprvkovými výpočty. This master’s thesis deal...

Magnetic properties and magnetocaloric effect in the HoNi1−xCuxIn (x=0, 0.1, 0.3, 0.4) intermetallic compounds

International Nuclear Information System (INIS)

Mo, Zhao-Jun; Shen, Jun; Yan, Li-Qin; Tang, Cheng-Chun; He, Xiao-Nan; Zheng, Xinqi; Wu, Jian-Feng; Sun, Ji-Rong; Shen, Bao-Gen

2014-01-01

The magnetic properties and magnetocaloric effect (MCE) in HoNi 1−x Cu x In (x=0, 0.1, 0.3, 0.4) compounds have been investigated. With the substitution of Cu for Ni, the Ho magnetic moment will cant from the c-axis, and form a complicated magnetic structure. These compounds exhibit two successive magnetic transitions with the increase in temperature. The large reversible magnetocaloric effects have been observed in HoNi 1−x Cu x In compounds around T ord , with no thermal and magnetic hysteresis loss. The large reversible isothermal magnetic entropy change (−ΔS M ) is 20.2 J/kg K and the refrigeration capacity (RC) reaches 356.7 J/kg for field changes of 5 T for HoNi 0.7 Cu 0.3 In. Especially, the value of −ΔS M (12.5 J/kg K) and the large RC (132 J/kg) are observed for field changes of 2 T for HoNi 0.9 Cu 0.1 In. Additionally, the values of RC are improved to 149 J/K for the field changes of 2 T due to a wide temperature span for the mix of HoNi 0.9 Cu 0.1 In and HoNi 0.7 Cu 0.3 In compounds with the mass ratio of 1:1. These compounds with excellent MCE are expected to have effective applications in magnetic refrigeration around 20 K. - Highlights: • For magnetic-field changes of 2 T, the values of RC are improved to 149 J/K. • MCEs of these compounds show no thermal and magnetic hysteresis. • Compounds show two successive magnetic transitions with the increase in temperature. • With the substitution of Cu for Ni, compounds form a complicated magnetic structure

Bone fluoride determination for clinical investigation of osteoporosis

International Nuclear Information System (INIS)

Krishnan, S.S.; McNeill, K.G.; Hitchman, A.J.W.; Mernagh, J.R.; Lin, S.C.; Harrison, J.E.

1984-01-01

Sodium fluoride is the therapeutic agent known to stimulate bone growth with net increase in bone mineral mass in patients afflicted with osteoporosis, a common crippling bone disease. In order to study the effect of sodium fluoride treatment, a method of analysis for fluoride in bone has been developed using Neutron Activation Analysis (NAA). The technique proved to be simple, fast, reliable and non-destructive. Thus the sample, often bone biopsy specimen, is available, after fluoride analysis, for further histological studies. NAA was used to analyze both fluoride and calcium in the bone and the results expressed as F/Ca ratio was meaningful since it normalizes the fluoride to bone mineral mass which is the important factor in this study. Four years of fluoride treatment of osteoporotics showed significant increase of bone mass (up to 30%) in several patients. These increases were associated with histological bone picture of fluorosis. In the case of patients with renal osteodystrophy, there was evidence that fluorosis contributes to the bone disease. 3 references, 2 figures, 2 tables

2,3-trans-3,4-trans-3,4-Dihydroxy-L-proline: An amino acid in toxic peptides of Amanita virosa mushrooms

Science.gov (United States)

Buku, A.; Faulstich, H.; Wieland, T.; Dabrowski, J.

1980-01-01

Among the four possible stereoisomers of 3,4-dihydroxy-L-proline,2,3-trans-3,4-trans-3,4-dihydroxy-L-proline (IV) had not been found in nature previously. It has now been detected as a component of virotoxins, toxic peptides of Amanita virosa mushrooms. Because periodate failed to effect an oxidative glycol splitting reaction, the two hydroxyl groups in positions 3 and 4 were expected to be in a trans configuration. Furthermore, the formation of a 4-lactone on treatment with acids pointed to the carboxyl group and the hydroxyl group at position 4 being in a cis configuration. These results are in agreement with structure IV only. Final proof for structure IV was given by NMR spectroscopy and direct comparison with the 2,3-cis-3,4-trans-3,4-dihydroxy-L-proline isomer. PMID:16592813

Electroacupuncture Ameliorates Acute Renal Injury in Lipopolysaccharide-Stimulated Rabbits via Induction of HO-1 through the PI3K/Akt/Nrf2 Pathways.

Science.gov (United States)

Yu, Jian-Bo; Shi, Jia; Zhang, Yuan; Gong, Li-Rong; Dong, Shu-An; Cao, Xin-Shun; Wu, Li-Li; Wu, Li-Na

2015-01-01

Electroacupuncture at select acupoints have been verified to protect against organ dysfunctions during endotoxic shock. And, heme oxygenase (HO)-1 as a phase II enzyme and antioxidant contributed to the protection of kidney in septic shock rats. The phosphatidylinositol 3-kinase (PI3K)-Akt pathway mediated the activation of NF-E2 related factor-2 (Nrf2), which was involved in HO-1 induction. To understand the efficacy of electroacupuncture stimulation in ameliorating acute kidney injury (AKI) through the PI3K/Akt/Nrf2 pathway and subsequent HO-1 upregulation, a dose of LPS 5mg/kg was administered intravenously to replicate the rabbit model of AKI induced by endotoxic shock. Electroacupuncture pretreatment was handled bilaterally at Zusanli and Neiguan acupoints for five consecutive days while sham electroacupuncture at non-acupoints as control. Results displayed that electroacupuncture stimulation significantly alleviated the morphologic renal damage, attenuated renal tubular apoptosis, suppressed the elevated biochemical indicators of AKI caused by LPS, enhanced the expressions of phospho-Akt, HO-1protein, Nrf2 total and nucleoprotein, and highlighted the proportions of Nrf2 nucleoprotein as a parallel. Furthermore, partial protective effects of elecroacupuncture were counteracted by preconditioning with wortmannin (the selective PI3K inhibitor), indicating a direct involvement of PI3K/Akt pathway. Inconsistently, wortmannin pretreatment made little difference to the expressions of HO-1, Nrf2 nucleoprotein and total protein, which indicated that PI3K/Akt may be not the only pathway responsible for electroacupuncture-afforded protection against LPS-induced AKI. These findings provide new insights into the potential future clinical applications of electroacupuncture for AKI induced by endotoxic shock instead of traditional remedies.

Synthesis of Multicolor Core/Shell NaLuF4:Yb3+/Ln3+@CaF2 Upconversion Nanocrystals

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Hui Li

2017-02-01

Full Text Available The ability to synthesize high-quality hierarchical core/shell nanocrystals from an efficient host lattice is important to realize efficacious photon upconversion for applications ranging from bioimaging to solar cells. Here, we describe a strategy to fabricate multicolor core @ shell α-NaLuF4:Yb3+/Ln3+@CaF2 (Ln = Er, Ho, Tm upconversion nanocrystals (UCNCs based on the newly established host lattice of sodium lutetium fluoride (NaLuF4. We exploited the liquid-solid-solution method to synthesize the NaLuF4 core of pure cubic phase and the thermal decomposition approach to expitaxially grow the calcium fluoride (CaF2 shell onto the core UCNCs, yielding cubic core/shell nanocrystals with a size of 15.6 ± 1.2 nm (the core ~9 ± 0.9 nm, the shell ~3.3 ± 0.3 nm. We showed that those core/shell UCNCs could emit activator-defined multicolor emissions up to about 772 times more efficient than the core nanocrystals due to effective suppression of surface-related quenching effects. Our results provide a new paradigm on heterogeneous core/shell structure for enhanced multicolor upconversion photoluminescence from colloidal nanocrystals.

Crystal growth, spectroscopic characterization and laser operation of Tm3+ and Ho3+ codoped LiLuF4 crystal

Science.gov (United States)

Zhao, C. C.; Hang, Y.; Zhang, L. H.; He, X. M.; Yin, J. G.; Gong, J.; Yu, T.; Chen, W. B.

2012-02-01

Laser crystal Tm3+ and Ho3+ codoped LiLuF4 with high optical quality was grown by Czochralski technique. Its absorption and fluorescence spectra were investigated. A continuous wave output power of 1.12 W at 2066 nm was obtained with a slope efficiency of 24% by use of diode pumping. In the Q-switched mode, a slope efficiency of 18.9% and a maximum average power of 0.65 W were obtained.

No calcium-fluoride-like deposits detected in plaque shortly after a sodium fluoride mouthrinse.

Science.gov (United States)

Vogel, G L; Tenuta, L M A; Schumacher, G E; Chow, L C

2010-01-01

Plaque 'calcium-fluoride-like' (CaF(2)-like) and fluoride deposits held by biological/bacterial calcium fluoride (Ca-F) bonds appear to be the source of cariostatic concentrations of fluoride in plaque fluid. The aim of this study was to quantify the amounts of plaque fluoride held in these reservoirs after a sodium fluoride rinse. 30 and 60 min after a 228 microg/g fluoride rinse, plaque samples were collected from 11 volunteers. Each sample was homogenized, split into 2 aliquots (aliquots 1 and 2), centrifuged, and the recovered plaque fluid combined and analyzed using microelectrodes. The plaque mass from aliquot 1 was retained. The plaque mass from aliquot 2 was extracted several times with a solution having the same fluoride, calcium and pH as the plaque fluid in order to extract the plaque CaF(2)-like deposits. The total fluoride in both aliquots was then determined. In a second experiment, the extraction completeness was examined by applying the above procedure to in vitro precipitates containing known amounts of CaF(2)-like deposits. Nearly identical fluoride concentrations were found in both plaque aliquots. The extraction of the CaF(2)-like precipitates formed in vitro removed more than 80% of these deposits. The results suggest that either CaF(2)-like deposits were not formed in plaque or, if these deposits had been formed, they were rapidly lost. The inability to form persistent amounts of CaF(2)-like deposits in plaque may account for the relatively rapid loss of plaque fluid fluoride after the use of conventional fluoride dentifrices or rinses. (c) 2010 S. Karger AG, Basel.

Sirtuin1 and autophagy protect cells from fluoride-induced cell stress

Science.gov (United States)

Suzuki, Maiko; Bartlett, John D.

2014-01-01

Sirtuin1 (SIRT1) is an (NAD+)-dependent deacetylase functioning in the regulation of metabolism, cell survival and organismal lifespan. Active SIRT1 regulates autophagy during cell stress, including calorie restriction, endoplasmic reticulum stress and oxidative stress. Previously, we reported that fluoride induces endoplasmic reticulum (ER) stress in ameloblasts responsible for enamel formation, suggesting that ER-stress plays a role in dental fluorosis. However, the molecular mechanism of how cells respond to fluoride-induced cell stress is unclear. Here, we demonstrate that fluoride activates SIRT1 and initiates autophagy to protect cells from fluoride exposure. Fluoride treatment of ameloblast-derived cells (LS8) significantly increased Sirt1 expression and induced SIRT1 phosphorylation resulting in the augmentation of SIRT1 deacetylase activity. To demonstrate that fluoride exposure initiates autophagy, we characterized the expression of autophagy related genes (Atg); Atg5, Atg7 and Atg8/LC3 and showed that both their transcript and protein levels were significantly increased following fluoride treatment. To confirm that SIRT1 plays a protective role in fluoride toxicity, we used resveratrol (RES) to augmented SIRT1 activity in fluoride treated LS8 cells. RES increased autophagy, inhibited apoptosis, and decreased fluoride cytotoxicity. Rats treated with fluoride (0, 50 and 100 ppm) in drinking water for 6 weeks had significantly elevated expression levels of Sirt1, Atg5, Atg7 and Atg8/LC3 in their maturation stage enamel organs. Increased protein levels of p-SIRT1, ATG5 and ATG8/LC3 were present in fluoride-treated rat maturation stage ameloblasts. Therefore, the SIRT1/autophagy pathway may play a critical role as a protective response to help prevent dental fluorosis. PMID:24296261

Sirtuin1 and autophagy protect cells from fluoride-induced cell stress.

Science.gov (United States)

Suzuki, Maiko; Bartlett, John D

2014-02-01

Sirtuin1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD(+))-dependent deacetylase functioning in the regulation of metabolism, cell survival and organismal lifespan. Active SIRT1 regulates autophagy during cell stress, including calorie restriction, endoplasmic reticulum (ER) stress and oxidative stress. Previously, we reported that fluoride induces ER-stress in ameloblasts responsible for enamel formation, suggesting that ER-stress plays a role in dental fluorosis. However, the molecular mechanism of how cells respond to fluoride-induced cell stress is unclear. Here, we demonstrate that fluoride activates SIRT1 and initiates autophagy to protect cells from fluoride exposure. Fluoride treatment of ameloblast-derived cells (LS8) significantly increased Sirt1 expression and induced SIRT1 phosphorylation resulting in the augmentation of SIRT1 deacetylase activity. To demonstrate that fluoride exposure initiates autophagy, we characterized the expression of autophagy related genes (Atg); Atg5, Atg7 and Atg8/LC3 and showed that both their transcript and protein levels were significantly increased following fluoride treatment. To confirm that SIRT1 plays a protective role in fluoride toxicity, we used resveratrol (RES) to augment SIRT1 activity in fluoride treated LS8 cells. RES increased autophagy, inhibited apoptosis, and decreased fluoride cytotoxicity. Rats treated with fluoride (0, 50, 100 and 125ppm) in drinking water for 6weeks had significantly elevated expression levels of Sirt1, Atg5, Atg7 and Atg8/LC3 in their maturation stage enamel organs. Increased protein levels of p-SIRT1, ATG5 and ATG8/LC3 were present in fluoride-treated rat maturation stage ameloblasts. Therefore, the SIRT1/autophagy pathway may play a critical role as a protective response to help prevent dental fluorosis. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis of the Complex Fluoride LiBaF3 through a Solvothermal Process

Institute of Scientific and Technical Information of China (English)

无

2002-01-01

The complex fluoride LiBaF3 is solvothermally synthesized at 180℃ and characterized by means of X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis and infrared spectroscopy. In the solvothermal process, the solvents, mole ratios of initial mixtures and reaction temperature play important roles in the growth of the single crystal.

Ozone decomposition in water studied by pulse radiolysis. 2. OH and HO4 as chain intermediates

International Nuclear Information System (INIS)

Staehelin, J.; Buehler, R.E.; Hoigne, J.

1984-01-01

Ozone decomposition in pure water involves a chain mechanism, initiated by the reaction OH - +O 3 and propogated by O 2 - and OH. In the present studies this chain is initiated by pulse radiolysis of aqueous solutions of ozone. The chain propogation steps were studied in two parts. By computer simulation of the rate curves, it is shown that from OH + O 3 and intermediate HO 4 must be formed, most likely a charge-transfer complex (HO.O 3 ), which eventually decays into HO 2 . The derived rate constants for the formation of the various species are included. The spectrum of HO 4 is derived. It is similar to the one of ozone, but the absorption coefficients are about 50% larger. In the presence of high ozone concentration, the dominant chain termination reactions are HO 4 + HO 4 and HO 4 + HO 3 . The effect on chain length, dose, overall rate, and pH and of added scavengers is described. The implications for the natural ozone decay mechanism are discussed

Water fluoridation in 40 Brazilian cities: 7 year analysis

Directory of Open Access Journals (Sweden)

Suzely Adas Saliba MOIMAZ

2013-01-01

Full Text Available Objectives Fluoride levels in the public water supplies of 40 Brazilian cities were analyzed and classified on the basis of risk/benefit balance. Material and Methods Samples were collected monthly over a seven-year period from three sites for each water supply source. The samples were analyzed in duplicate in the laboratory of the Center for Research in Public Health - UNESP using an ion analyzer coupled to a fluoride-specific electrode. Results A total of 19,533 samples were analyzed, of which 18,847 were artificially fluoridated and 686 were not artificially fluoridated. In samples from cities performing water fluoridation, 51.57% (n=9,720 had fluoride levels in the range of 0.55 to 0.84 mg F/L; 30.53% (n=5,754 were below 0.55 mg F/L and 17.90% (n=3,373 were above 0.84 mg F/L (maximum concentration=6.96 mg F/L. Most of the cities performing fluoridation that had a majority of samples with fluoride levels above the recommended parameter had deep wells and more than one source of water supply. There was some variability in the fluoride levels of samples from the same site and between collection sites in the same city. Conclusions The majority of samples from cities performing fluoridation had fluoride levels within the range that provides the best combination of risks and benefits, minimizing the risk of dental fluorosis while preventing dental caries. The conduction of studies about water distribution systems is suggested in cities with high natural fluoride concentrations in order to optimize the use of natural fluoride for fluoridation costs and avoid the risk of dental fluorosis.

Chronic Fluoride Toxicity: Dental Fluorosis

OpenAIRE

DenBesten, Pamela; Li, Wu

2011-01-01

Dental fluorosis occurs as a result of excess fluoride ingestion during tooth formation. Enamel fluorosis and primary dentin fluorosis can only occur when teeth are forming, and therefore fluoride exposure (as it relates to dental fluorosis) occurs during childhood. In the permanent dentition, this would begin with the lower incisors, which complete mineralization at approximately 2–3 years of age, and end after mineralization of the third molars. The white opaque appearance of fluorosed enam...

Water Fluoridation Statistics - Percent of PWS population receiving fluoridated water

Data.gov (United States)

U.S. Department of Health & Human Services — 2000-2014. Water Fluoridation Statistics is a biennial report of the percentage and number of people receiving fluoridated water from 2000 through 2014, originally...

Water Fluoridation Statistics - Percent of PWS population receiving fluoridated water

Data.gov (United States)

U.S. Department of Health & Human Services — 2000-2014 Water Fluoridation Statistics is a biennial report of the percentage and number of people receiving fluoridated water from 2000 through 2014, originally...

Fluoride releasing and enamel demineralization around orthodontic brackets by fluoride-releasing composite containing nanoparticles.

Science.gov (United States)

Melo, Mary A S; Morais, Weslanny A; Passos, Vanara F; Lima, Juliana P M; Rodrigues, Lidiany K A

2014-05-01

Fluoride-containing materials have been suggested to control enamel demineralization around orthodontic brackets during the treatment with fixed appliances. The improvement of their properties has been made through innovations, such as the application of nanotechnology by incorporation of nanofillers. This in vitro study evaluated the capacity of fluoride releasing and enamel demineralization inhibition of fluoride-releasing nanofilled cement around orthodontic brackets using an artificial caries biofilm model. Forty bovine enamel discs were selected by evaluating surface microhardness and randomized into four groups (n = 10): non-fluoride-releasing microfilled composite, fluoride-releasing microfilled composite, resin-modified glass ionomer cement (RMGI), and fluoride-releasing nanofilled composite (FN). After brackets bonding in each disc, the specimens were subjected to a cariogenic challenge through a Streptococcus mutans biofilm model. After the experimental period, the biofilm formed around the brackets was collected for fluoride analysis and the mineral loss around the brackets was determined by integrated demineralization via cross-sectional microhardness measurement at 20 and 70 μm from the bracket margin. Additionally, samples of each group were subjected to energy-dispersive X-ray spectroscopy (EDX) analysis examined under a scanning electron microscopy (SEM). ANOVA followed by Tukey test were applied for fluoride concentration and mineral loss data, respectively. At both distances, only RMGI statistically differed from the other groups presenting the lowest demineralization, although there was a trend to a lower demineralization of enamel around brackets in FN group. Similar condition was found to fluoride concentration and EDX/SEM analysis. Under the cariogenic exposure condition of this study, the fluoride-releasing nanofilled material had similar performance to fluoride-releasing microfilled materials. The presence of nanofillers in the fluoride

Comparative proteomic analysis of fluoride treated rat bone provides new insights into the molecular mechanisms of fluoride toxicity.

Science.gov (United States)

Wei, Yan; Zeng, Beibei; Zhang, Hua; Chen, Cheng; Wu, Yanli; Wang, Nanlan; Wu, Yanqiu; Zhao, Danqing; Zhao, Yuxi; Iqbal, Javed; Shen, Liming

2018-07-01

Long-term excessive intake of fluoride (F) could lead to chronic fluorosis. To explore the underlying molecular mechanisms, present study is designed to elucidate the effect of fluoride on proteome expression of bone in sodium fluoride (NaF)-treated SD rats. Hematoxylin and eosin (H&E) staining was used to determine the severity of osteofluorosis, and bone samples were submitted for iTRAQ analysis. The results showed that the cortical thickness and trabecular area of femur bone in medium- and high-dose groups were higher than in control group. Contrary to this, trabecular area was reduced in the low-dose group, indicating that the bone mass was increased in medium- and high-dose groups, and decreased in the low-dose group. Thirteen (13), 35, and 34 differentially expressed proteins were identified in low-, medium-, and high-dose group, respectively. The medium- and high-dose groups shared a more similar protein expression pattern. These proteins were mainly associated with collagen metabolism, proteoglycans (PGs), matrix metalloproteinases (MMPs), etc. The results suggested that the effect of NaF on SD rats is in a dose-dependent manner. Some key proteins found here may be involved in affecting the bone tissues and bone marrow or muscle, and account for the complex pathology and clinical symptoms of fluorosis. Copyright © 2018 Elsevier B.V. All rights reserved.

Giant Magnetic Fluctuations at the Critical Endpoint in Insulating HoMnO3

Science.gov (United States)

Choi, Y. J.; Lee, N.; Sharma, P. A.; Kim, S. B.; Vajk, O. P.; Lynn, J. W.; Oh, Y. S.; Cheong, S.-W.

2013-04-01

Although abundant research has focused recently on the quantum criticality of itinerant magnets, critical phenomena of insulating magnets in the vicinity of critical endpoints (CEP’s) have rarely been revealed. Here we observe an emergent CEP at 2.05 T and 2.2 K with a suppressed thermal conductivity and concomitant strong critical fluctuations evident via a divergent magnetic susceptibility (e.g., χ''(2.05T,2.2K)/χ''(3T,2.2K)≈23,500%, comparable to the critical opalescence in water) in the hexagonal insulating antiferromagnet HoMnO3.

Oral fluoride levels 1 h after use of a sodium fluoride rinse: effect of sodium lauryl sulfate.

Science.gov (United States)

Vogel, Gerald L; Schumacher, Gary E; Chow, Laurence C; Tenuta, Livia M A

2015-01-01

Increasing the concentration of free fluoride in oral fluids is an important goal in the use of topical fluoride agents. Although sodium lauryl sulfate (SLS) is a common dentifrice ingredient, the influence of this ion on plaque fluid and salivary fluid fluoride has not been examined. The purpose of this study was to investigate the effect of SLS on these parameters and to examine the effect of this ion on total (or whole) plaque fluoride, an important source of plaque fluid fluoride after a sufficient interval following fluoride administration, and on total salivary fluoride, a parameter often used as a surrogate measure of salivary fluid fluoride. Ten subjects accumulated plaque for 48 h before rinsing with a 12 mmol/l NaF (228 µg/g F) rinse containing or not containing 0.5% (w/w) SLS. SLS had no statistically significant effect on total plaque and total saliva fluoride but significantly increased salivary fluid and plaque fluid fluoride (by 147 and 205%, respectively). These results suggest that the nonfluoride components of topical agents can be manipulated to improve the fluoride release characteristics from oral fluoride reservoirs and that statistically significant change may be observed in plaque fluid and salivary fluid fluoride concentrations that may not be observed in total plaque and total saliva fluoride concentrations.

The cariostatic mechanisms of fluoride

OpenAIRE

Kata Rošin-Grget; Kristina Peroš; Ivana Šutej; Krešimir Bašić

2013-01-01

This article discusses the possible cariostatic mechanisms of the action of fluoride. In the past, fluoride inhibition of caries was ascribed to reduced solubility of enamel due to incorporation of fluoride (F–) into the enamel minerals. The present evidence from clinical and laboratory studies suggests that the caries-preventive mode of action of fluoride is mainly topical. There is convincing evidence that fluoride has a major effect on demineralisation and remineralisation of dental hard t...

A role for PERK in the mechanism underlying fluoride-induced bone turnover

International Nuclear Information System (INIS)

Sun, Fei; Li, Xining; Yang, Chen; Lv, Peng; Li, Guangsheng; Xu, Hui

2014-01-01

While it has been well-documented that excessive fluoride exposure caused the skeletal disease and osteoblasts played a critical role in the advanced skeletal fluorosis, the underlying mechanism that mediated these effects remain poorly understood. The present study was undertaken to examine the effect of fluoride on bone of rats and MC3T3-E1 cells in vitro. Herein we found pathological features of high bone turnover in fluoride-treated rats, which was supported by an increase of osteogenic and osteoclastogenic genes expression in different stages of fluoride exposure. The skeletal toxicity of fluoride was accompanied by activation of endoplasmic reticulum (ER) stress and subsequent unfolded protein response (UPR). A novel finding of this study was that expression of PKR-like endoplasmic reticulum kinase (PERK) was the same trend with receptor activator for nuclear factor-κ B ligand (RANKL), and NF-E2 p45-related factor 2 (Nrf2) was the same trend with Runt-related transcription factor 2 (Runx2) in bones of rats exposed to varied fluoride condition. Based on these data, we hypothesized that up-regulation of PERK probably played a role in mediating bone turnover induced by fluoride. Action of fluoride on MC3T3-E1 cells differentiation was demonstrated through analysis of alkaline phosphatase (ALP) activity and mineralized nodules formation. Meantime, an increase of binding immunoglobulin protein (BiP) expression indicated the active ER stress in cells exposed to various dose of fluoride. Blocking PERK expression using siRNA showed the obvious decrease of osteogenic and osteoclastogenic factors expression in MC3T3-E1 cells exposed to certain dose of fluoride that could positively stimulate osteoblastic viability. In conclusion these findings underscore the importance of PERK in modulating fluoride induced bone formation and bone resorption. Understanding the link between PERK and bone turnover could probe into the mechanism underlying different bone lesion of

Epigallocatechin-3-gallate (EGCG) protects skin cells from ionizing radiation via heme oxygenase-1 (HO-1) overexpression

International Nuclear Information System (INIS)

Zhu Wei; Xu Jing; Ge Yangyang

2014-01-01

Epigallocatechin-3-gallate (EGCG), the major polyphenolic constituent of green tea, is a potent antioxidant and free radical scavenger that may have therapeutic applications for the treatment of many disorders. Radiation therapy is widely used for the treatment of various types of cancers; however, radiation-induced skin injury remains a serious concern. EGCG has not yet been reported as protecting skin cells against ionizing radiation. In the present study, we investigated whether EGCG confers cytoprotection against ionizing radiation. We found that, compared with the control, pretreatment with EGCG significantly enhanced the viability of human skin cells that were irradiated with X-rays, and decreased apoptosis induced by X-ray irradiation. Mito-Tracker assay showed that EGCG suppressed the damage to mitochondria induced by ionizing radiation via upregulation of SOD2. Reactive oxygen species (ROS) in HaCaT cells were significantly reduced when pretreated with EGCG before irradiation. Radiation-induced γH2AX foci, which are representative of DNA double-strand breaks, were decreased by pretreatment with EGCG. Furthermore, EGCG induced the expression of the cytoprotective molecule heme oxygenase-1 (HO-1) in a dose-dependent manner via transcriptional activation. HO-1 knockdown or treatment with the HO-1 inhibitor tin protoporphyrin (SnPPIX) reversed the protective role of EGCG, indicating an important role for HO-1. These results suggest that EGCG offers a new strategy for protecting skin against ionizing radiation. (author)

Caries and fluoridated water in two Brazilian municipalities with low prevalence of the disease

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Mariângela Guanaes Bortolo da Cruz

2018-04-01

Full Text Available ABSTRACT OBJECTIVE To analyze the association between exposure to fluoridated water and dental caries in a context of widespread use of fluoride toothpaste in Brazil, in a scenario of low prevalence of the disease. METHODS This is a cross-sectional observational study, of the census type, in the form of a double population-based epidemiological survey carried out in two municipalities of the state of São Paulo in 2014. The sample consisted of adolescents aged 11 and 12 years, exposed (n = 184 or not exposed (n = 128 to fluoridated water for at least five years. The populations studied lived in communities of the same geographic region and had small demographic size and similar socioeconomic classification, differing only in the exposure (Silveiras or not exposure (São José do Barreiro to fluoridated water. The experience, magnitude, and degree of polarization of dental caries in these populations were analyzed using the DMFT and SiC indexes, and the association was tested using Pearson’s chi-square statistics and prevalence ratio between those not exposed and those exposed to fluoridated water. RESULTS Although caries experience (DMFT ≥ 1 was not associated with exposure to fluoridated water (chi-square = 1.78; p = 0.18; α = 5%, a significant difference was observed in the magnitude with which the disease reached the population: the means of DMFT were 1.76 in those exposed and 2.60 in those not exposed and the means of SiC were 4.04 and 6.16, respectively. The degree of polarization, indicated by the percentage of subjects with DMFT = 0, was different, being it higher (41.8% in subjects exposed and lower (34.3% in subjects not exposed. The prevalence ratio between those not exposed and those exposed was 1.13, indicating little expressiveness in prevalence difference. CONCLUSIONS Exposure to fluoridated water implied lower mean values for the DMFT and SiC indexes, even in the presence of the concomitant exposure to fluoridated toothpaste

Small molecule fluoride toxicity agonists.

Science.gov (United States)

Nelson, James W; Plummer, Mark S; Blount, Kenneth F; Ames, Tyler D; Breaker, Ronald R

2015-04-23

Fluoride is a ubiquitous anion that inhibits a wide variety of metabolic processes. Here, we report the identification of a series of compounds that enhance fluoride toxicity in Escherichia coli and Streptococcus mutans. These molecules were isolated by using a high-throughput screen (HTS) for compounds that increase intracellular fluoride levels as determined via a fluoride riboswitch reporter fusion construct. A series of derivatives were synthesized to examine structure-activity relationships, leading to the identification of compounds with improved activity. Thus, we demonstrate that small molecule fluoride toxicity agonists can be identified by HTS from existing chemical libraries by exploiting a natural fluoride riboswitch. In addition, our findings suggest that some molecules might be further optimized to function as binary antibacterial agents when combined with fluoride. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fluoride varnishes and enamel caries

NARCIS (Netherlands)

Bruyn, Hugo de

1987-01-01

Topical fluoride applications have the aim of increasing the fluoride uptake in enamel and consequently reducing caries. In the early ‘60s fluoride varnishes were introduced because they had a long contact period with the enamel which resulted in a higher fluoride uptake than from other topical

Comparison of La3+ and mixed rare earths-loaded magnetic chitosan beads for fluoride adsorption

DEFF Research Database (Denmark)

Liang, Peng; An, Ruiqi; Li, Ruifen

2018-01-01

La3+ and mixed-rare earth magnetic chitosan beads (MCLB and MCLRB) were successfully prepared for fluoride removal, respectively. The adsorbents were characterized by scanning electron microscope and magnetic response. Batch experiments were carried out to investigate the adsorbent performance...

Competitive adsorption characteristics of fluoride and phosphate on calcined Mg-Al-CO{sub 3} layered double hydroxides

Energy Technology Data Exchange (ETDEWEB)

Cai, Peng [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Zheng, Hong, E-mail: zhengh@cugb.edu.cn [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Wang, Chong; Ma, Hongwen; Hu, Jianchao; Pu, Yubing; Liang, Peng [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China)

2012-04-30

Highlights: Black-Right-Pointing-Pointer The influences of pH, contact time and order of addition of the anions were obtained. Black-Right-Pointing-Pointer The kinetic data were found to fit very well the pseudo second-order kinetic model. Black-Right-Pointing-Pointer Data of equilibrium experiments were fitted well to Langmuir isotherm. Black-Right-Pointing-Pointer The competitive monolayer adsorption capacities obviously decreased. Black-Right-Pointing-Pointer ATR-FTIR proofs of competitive adsorption were obtained. - Abstract: With synthetic wastewater, competitive adsorption characteristics of fluoride and phosphate on calcined Mg-Al-CO{sub 3} layered double hydroxides (CLDH) were investigated. A series of batch experiments were performed to study the influence of various experimental parameters, such as pH, contact time, and order of addition of the anions on the competitive adsorption of fluoride and phosphate on CLDH. It was found that the optimal pH is around 6 and it took 24 h to attain equilibrium when fluoride and phosphate were simultaneous added. The order of addition of anions influenced the adsorption of fluoride and phosphate on CLDH. The kinetic data were analyzed using the pseudo first-order and pseudo second-order models and they were found to fit very well the pseudo second-order kinetic model. Data of equilibrium experiments were fitted well to Langmuir isotherm and the competitive monolayer adsorption capacities of fluoride and phosphate were found to be obviously lower than those of single anion at 25 Degree-Sign C. The results of X-ray diffraction, Scanning Electron Microscopy with energy-dispersive X-ray analyses, and ATR-FTIR demonstrate that the adsorption mechanism involves the rehydration of mixed metal oxides and concomitant intercalation of fluoride and phosphate ions into the interlayer to reconstruct the initial LDHs structure.

Properties of sodium borosilicate glasses/Al2O3 sintered composites containing fluorides. Gan Fukkabutsu hokei san natoriumu garasu to alumina fukugo shoketsutai no bussei

Energy Technology Data Exchange (ETDEWEB)

Ryu, Bonggi; Yasui, I [The Univ. of Tokyo, Tokyo (Japan). Inst. of Industrial Science

1993-06-01

Glass/alumina sintered composites were synthesized from sodium borosilicate glass powder containing fluorides like AlF3 and NaF3, and Al2O3, and change in material properties was examined. Glass compositions of B2O3 and Na2O greatly affected the crystal phase and material properties. Nephelin crystal phase was extracted by the reaction of Na2O, NaF2, SiO2 and Al2O3 when B/Na<1. Coefficient of thermal expansion increased with the increase of Na/Si ratio. The residual amount of fluorides of sintered materials in nitrogen atmosphere was higher than that of air, and differed with the type of fluoride. The F[sup -] of NaF is bonded with Si of glass network and forms quiet stable glass structure, whereas, F[sup -] of AlF3 reacts with Si[sup 4+] forming SiF4 which is vaporized. Sintering temperature and dielectric constant of sintered materials containing fluoride was lower than the sintered materials without fluorides addition, however, at a sintering temperature range of 100 to 150[degree]C, it was inferred that this was because of the increase in voids due to SiF4 formed in the reaction. 16 refs., 17 figs., 3 tabs.

Determination of zirconium by fluoride ion selective electrode

International Nuclear Information System (INIS)

Mahanty, B.N.; Sonar, V.R.; Gaikwad, R.; Raul, S.; Das, D.K.; Prakash, A.; Afzal, Md.; Panakkal, J.P.

2010-01-01

Full text: Zirconium is used in a wide range of applications including nuclear clad, catalytic converters, surgical appliances, metallurgical furnaces, superconductors, ceramics, lamp filaments, anti corrosive alloys and photographical purposes. Irradiation testing of U-Zr and U-Pu-Zr fuel pins has also demonstrated their feasibility as fuel in liquid metal reactors. Different methods that are employed for the determination of zirconium are spectrophotometry, potentiometry, neutron activation analysis and mass spectrometry. Ion-selective electrode (ISE), selective to zirconium ion has been studied for the direct potentiometric measurements of zirconium ions in various samples. In the present work, an indirect method has been employed for the determination of zirconium in zirconium nitrate sample using fluoride ion selective electrode. This method is based on the addition of known excess amount of fluoride ion to react with the zirconium ion to produce zirconium tetra fluoride at about pH 2-3, followed by determination of residual fluoride ion selective electrode. The residual fluoride ion concentrations were determined from the electrode potential data using calibration plot. Subsequently, zirconium ion concentrations were determined from the concentration of consumed fluoride ions. A precision of about 2% (RSD) with the mean recovery of more than 94% has been achieved for the determination of zirconium at the concentration of 4.40 X 10 -3 moles lit -1

White light emission and effect of annealing on the Ho{sup 3+}–Yb{sup 3+} codoped BaCa{sub 2}Al{sub 8}O{sub 15} phosphor

Energy Technology Data Exchange (ETDEWEB)

Kumari, Astha; Rai, Vineet Kumar, E-mail: vineetkrrai@yahoo.co.in

2015-12-15

Graphical abstract: The upconversion emission spectra of the Ho{sup 3+}/Yb{sup 3+} doped/codoped BaCa{sub 2}Al{sub 8}O{sub 15} phosphors with different doping concentrations of Ho{sup 3+}/Yb{sup 3+} ions along with UC emission spectrum of the white light emitting phosphor annealed at 800 °C. - Highlights: • BaCa{sub 2}Al{sub 8}O{sub 15} phosphors codoped with Ho{sup 3+}–Yb{sup 3+} have been prepared by combustion method. • Phosphor annealed at 800 °C, illuminate an intense white light upon NIR excitation. • The sample annealed at higher temperatures emits in the pure green region. • The colour emitted persists in the white region even at high pump power density. • Developed phosphor is suitable for making upconverters and WLEDs. - Abstract: The BaCa{sub 2}Al{sub 8}O{sub 15} (BCAO) phosphors codoped with suitable Ho{sup 3+}–Yb{sup 3+} dopant concentration prepared by combustion method illuminate an intense white light upon near infrared diode laser excitation. The structural analysis of the phosphors and the detection of impurity contents have been performed by using the X-Ray Diffraction, FESEM and FTIR analysis. The purity of white light emitted from the sample has been confirmed by the CIE chromaticity diagram. Also, the white light emitted from the sample persists with the variation of pump power density. The phosphors emit upconversion (UC) emission bands in the blue, green and red region (three primary colours required for white light emission) along with one more band in the near infrared region of the electromagnetic spectrum. On annealing the white light emitting sample at higher temperatures, the sample starts to emit green colour and also the intensity of green and red UC emission bands get enhanced largely.

Phase equilibria of the Mo-Al-Ho ternary system

Energy Technology Data Exchange (ETDEWEB)

Li, Yitai; Chen, Xiaoxian; Liu, Hao [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials; Zhan, Yongzhong [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials; Guangxi Univ., Nanning (China). Center of Ecological Collaborative Innovation for Aluminum Industry

2017-08-15

Investigation into the reactions and phase equilibria of transition metal elements (i.e. Mo, Zr, Cr, V and Ti), Al and rare earths is academically and industrially important for the development of both refractory alloys and lightweight high-temperature materials. In this work, the equilibria of the Mo-Al-Ho ternary system at 773 K have been determined by using X-ray powder diffraction and scanning electron microscopy equipped with energy dispersive X-ray analysis. A new ternary phase Al{sub 4}Mo{sub 2}Ho has been found and the other ternary phase Al{sub 43}Mo{sub 4}Ho{sub 6} is observed. Ten binary phases in the Al-Mo and Al-Ho systems, including Al{sub 17}Mo{sub 4} rather than Al{sub 4}Mo, have been determined to exist at 773 K. The homogeneity ranges of AlMo{sub 3} and Al{sub 8}Mo{sub 3} phase are 7.5 at.% and 1 at.%, respectively. According to the phase-disappearing method, the maximum solubility of Al in Mo is about 16 at.%.

Alimentary fluoride intake in preschool children

Directory of Open Access Journals (Sweden)

Lencova Erika

2011-10-01

Full Text Available Abstract Background The knowledge of background alimentary fluoride intake in preschool children is of utmost importance for introducing optimal and safe caries preventive measures for both individuals and communities. The aim of this study was to assess the daily fluoride intake analyzing duplicate samples of food and beverages. An attempt was made to calculate the daily intake of fluoride from food and swallowed toothpaste. Methods Daily alimentary fluoride intake was measured in a group of 36 children with an average age of 4.75 years and an average weight of 20.69 kg at baseline, by means of a double plate method. This was repeated after six months. Parents recorded their child's diet over 24 hours and collected duplicated portions of food and beverages received by children during this period. Pooled samples of food and beverages were weighed and solid food samples were homogenized. Fluoride was quantitatively extracted from solid food samples by a microdiffusion method using hexadecyldisiloxane and perchloric acid. The content of fluoride extracted from solid food samples, as well as fluoride in beverages, was measured potentiometrically by means of a fluoride ion selective electrode. Results Average daily fluoride intake at baseline was 0.389 (SD 0.054 mg per day. Six months later it was 0.378 (SD 0.084 mg per day which represents 0.020 (SD 0.010 and 0.018 (SD 0.008 mg of fluoride respectively calculated per kg bw/day. When adding the values of unwanted fluoride intake from the toothpaste shown in the literature (0.17-1.21 mg per day the estimate of the total daily intake of fluoride amounted to 0.554-1.594 mg/day and recalculated to the child's body weight to 0.027-0.077 mg/kg bw/day. Conclusions In the children studied, observed daily fluoride intake reached the threshold for safe fluoride intake. When adding the potential fluoride intake from swallowed toothpaste, alimentary intake reached the optimum range for daily fluoride intake

Combined electrocoagulation and electroflotation for removal of fluoride from drinking water.

Science.gov (United States)

Zuo, Qianhai; Chen, Xueming; Li, Wei; Chen, Guohua

2008-11-30

A combined electrocoagulation (EC) and electroflotation (EF) process was proposed to remove fluoride from drinking water. Its efficacy was investigated under different conditions. Experimental results showed that the combined process could remove fluoride effectively. The total hydraulic retention time required was only 30 min. After treatment, the fluoride concentration was reduced from initial 4.0-6.0mg/L to lower than 1.0mg/L. The influent pH value was found to be a very important variable that affected fluoride removal significantly. The optimal influent pH range is 6.0-7.0 at which not only can effective defluoridation be achieved, but also no pH readjustment is needed after treatment. In addition, it was found that SO(4)(2-) had negative effect; Ca(2+) had positive effect; while Cl(-) had little effect on the fluoride removal. The EC charge loading, EF charge loading and energy consumption were 3.0 Faradays/m(3), 1.5 Faradays/m(3), and 1.2 kWh/m(3), respectively, under typical conditions where fluoride was reduced from initial 4.0 to 0.87 mg/L.

Diode-pumped efficient laser operation and spectroscopy of Tm,Ho:YVO 4

Science.gov (United States)

Li, G.; Yao, B. Q.; Meng, P. B.; Duan, X. M.; Ju, Y. L.; Wang, Y. Z.

2011-04-01

Spectroscopic characterization of co-doped Tm,Ho:YVO 4 crystal grown by the Czochralski method has been performed including absorption spectrum, emitting spectrum and luminescence decay lifetime. The polarization emitting spectrum around 2 μm is accomplished by exciting a singly Ho 3+ doped YVO 4 crystal to exclude the influence of Tm 3+3F 4- 3H 6 transition and the emission cross section is deduced from both Fuchtbauer-Ladenburg (F-L) equation and reciprocity method (RM). In addition, we report up to 10.4 W continuous wave (CW) output with a conversion efficiency of 40% and 10.3 W Q-Switch output with 12.5 kHz pulse repetition rate of diode-pumped cryogenic Tm,Ho:YVO 4 laser. For Q-Switch operation, the minimum pulse width of 28.2 ns is obtained, all of which demonstrate that the Tm,Ho:YVO 4 is excellent laser material for 2 μm radiation.

Short-wavelength luminescence in Ho{sup 3+}-doped KGd(WO{sub 4}){sub 2} crystals

Energy Technology Data Exchange (ETDEWEB)

Malinowski, M., E-mail: m.malinowski@elka.pw.edu.p [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland); Kaczkan, M.; Stopinski, S.; Piramidowicz, R. [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland); Majchrowski, A. [Institute of Applied Physics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland)

2009-12-15

Emissions from the high-lying excited states, energy transfer and upconversion processes are investigated in Ho{sup 3+}-activated KGd(WO{sub 4}){sub 2} crystal. The spectral assignment based on time-resolved emission spectra allowed to identify various near ultra-violet (UV), blue and green emissions starting from the excited {sup 3}H{sub 5}, {sup 5}G{sub 4}, {sup 5}G{sub 5}, {sup 5}F{sub 3} and {sup 5}S{sub 2} levels. The temporal behavior of these transitions after pulsed excitation was analyzed as a function of temperature and holmium ions concentration. The shortening and nonexponentiality of the decays, observed with increasing activator concentrations, indicated cross-relaxation (CR) among the Ho{sup 3+} ions. Cross-relaxation rates were experimentally determined as a function of activator concentration and used to evaluate the values of the nearest-neighbor trapping rates X{sub 01} and to model the decays. It was observed that KGW, despite higher than in YAG maximum phonon energy of about 900 cm{sup -1}, is more efficient short-wavelength emitter than YAG. Examples of the excited-state absorption (ESA) and energy transfer (ET) mechanisms responsible for the upconverted, short-wavelength emissions were identified by analyzing fluorescence dynamics and possible energy resonances.

Milk fluoridation for the prevention of dental caries

Directory of Open Access Journals (Sweden)

Jolán Bánóczy

2013-11-01

Full Text Available The aim of this review is to give an overview of 55 years experience of milk fluoridation and draw conclusions about the applicability of the method. Fluoridated milk was first investigated in the early 1950s, almost simultaneously in Switzerland, the USA and Japan. Stimulated by the favourable results obtained from these early studies, the establishment of The Borrow Dental Milk Foundation (subsequently The Borrow Foundation in England gave an excellent opportunity for further research, both clinical and non-clinical, and a productive collaboration with the World Health Organization which began in the early 1980s. Numerous peer-reviewed publications in international journals showed clearly the bioavailability of fluoride in various types of milk. Clinical trials were initiated in the 1980s – some of these can be classed as randomised controlled trials, while most of the clinical studies were community preventive programmes. Conclusion. These evaluations showed clearly that the optimal daily intake of fluoride in milk is effective in preventing dental caries. The amount of fluoride added to milk depends on background fluoride exposure and age of the children: commonly in the range 0.5 to 1.0 mg per day. An advantage of the method is that a precise amount of fluoride can be delivered under controlled conditions. The cost of milk fluoridation programmes is low, about € 2 to 3 per child per year. Fluoridation of milk can be recommended as a caries preventive measure where the fluoride concentration in drinking water is suboptimal, caries experience in children is significant, and there is an existing school milk programme.

Milk fluoridation for the prevention of dental caries.

Science.gov (United States)

Bánóczy, Jolán; Rugg-Gunn, Andrew; Woodward, Margaret

2013-11-01

The aim of this review is to give an overview of 55 years experience of milk fluoridation and draw conclusions about the applicability of the method. Fluoridated milk was first investigated in the early 1950s, almost simultaneously in Switzerland, the USA and Japan. Stimulated by the favourable results obtained from these early studies, the establishment of The Borrow Dental Milk Foundation (subsequently The Borrow Foundation) in England gave an excellent opportunity for further research, both clinical and non-clinical, and a productive collaboration with the World Health Organization which began in the early 1980s. Numerous peer-reviewed publications in international journals showed clearly the bioavailability of fluoride in various types of milk. Clinical trials were initiated in the 1980s - some of these can be classed as randomised controlled trials, while most of the clinical studies were community preventive programmes. These evaluations showed clearly that the optimal daily intake of fluoride in milk is effective in preventing dental caries. The amount of fluoride added to milk depends on background fluoride exposure and age of the children: commonly in the range 0.5 to 1.0 mg per day. An advantage of the method is that a precise amount of fluoride can be delivered under controlled conditions. The cost of milk fluoridation programmes is low, about € 2 to 3 per child per year. Fluoridation of milk can be recommended as a caries preventive measure where the fluoride concentration in drinking water is suboptimal, caries experience in children is significant, and there is an existing school milk programme. Copyright © 2013 by Academy of Sciences and Arts of Bosnia and Herzegovina.

Preparation of Ho3+/Tm3+ Co-doped Lanthanum Tungsten Germanium Tellurite Glass Fiber and Its Laser Performance for 2.0 μm

Science.gov (United States)

Zhou, Dechun; Bai, Xuemei; Zhou, Hang

2017-03-01

Ho3+/Tm3+ co-doped 50TeO2-25GeO2-3WO3-5La2O3-3Nb2O5-5Li2O-9BaF2 glass fiber is prepared with the rod-tube drawing method of 15 μm core diameter and 125 μm inner cladding diameter applied in the 2.0 μm-infrared laser. The 2.0 μm luminescence properties of the core glass are researched and the fluorescence intensity variation for different Tm3+ doping concentration is systematically analyzed. The results show that the 2.0 μm luminescence of Ho3+ is greatly influenced by the doping concentration ratio of Ho3+ to Tm3+ and that the maximum fluorescence intensity of the core glass can be obtained and its emission cross section can reach 0.933 × 10-21 cm2 when the sensitized proportion of holmium to thulium is 0.3 to 0.7 (mol%). Simultaneously, the maximum phonon energy of the core glass sample is 753 cm-1, which is significantly lower than that of silicate, gallate and germanate glass and the smaller matrix phonon energy can be conductive to the increase 2.0 μm-band emission intensity. The continuous laser with the maximum laser output power of 0.993 W and 2051 nm -wavelength of 31.9%-slope efficiency is output within the 0.5 m glass fiber and the experiment adopts 1560 nm erbium-doped fiber laser(EDFL) as the pump source and the self-built all-fiber laser. Therefore, the glass fiber has excellent laser characteristics and it is suitable for the 2.0 μm-band laser.

Preparation and study of chlorine mono-fluoride and of chlorine oxi-fluorides; Preparation et etude du monofluorure et des oxyfluorures de chlore

Energy Technology Data Exchange (ETDEWEB)

Macheteau, Yves

1969-07-01

The objective of this engineering school report was to be a contribution to the study of a family of fluorine compounds: chlorine mono-fluoride (ClF), chlorine fluoride oxide (ClOF), chloryl fluoride (ClO{sub 2}F), perchloryl fluoride (ClO{sub 3}F) and perchloryl oxi-fluoride (ClO{sub 4}F). Such a study required very pure products to be obtained in order to be able to characterize them by different methods (infrared, micro-sublimation, and chromatography). The thermolysis of ClO{sub 2}F and ClO{sub 4}F has been particularly studied, and magnetic resonance has been used to establish a relationship between fluorine chemical displacement and the electro-negativity of the F-X bond where X represents the atom group to which fluorine is bonded.

Comparative evaluation of fluoride release from PRG-composites and compomer on application of topical fluoride: An in-vitro study

Directory of Open Access Journals (Sweden)

Dhull K

2009-03-01

Full Text Available Aims and Objective: To determine the fluoride release from Giomer and Compomer, using different topical fluoride regimes, and to compare the amount of fluoride release from giomer with that of compomer. Materials and Method: Forty-eight specimens of each giomer and compomer were divided into four treatment groups, namely, control group, fluoridated dentifrice (500 ppm once daily group, fluoridated dentifrice (500 ppm twice daily group, fluoridated dentifrice (500 ppm once daily + fluoridated mouthwash (225 ppm group. Each specimen was suspended in demineralizing solution for six hours and remineralizing solution for 18 hours. Fluoride release was measured in both the demineralizing solution and remineralizing solution daily for seven days. Total daily fluoride release for each specimen was calculated by adding the amount released in the demineralizing solution to that released in remineralizing solution. Results and Conclusion: The fluoride release (ppm was found to be more in Giomer when compared to Compomer. The fluoride released from Giomer and Compomer was significantly greater in the acidic demineralizing solution than in the neutral remineralizing solution. It was found that increasing fluoride exposure significantly increased fluoride release from the giomer and compomer. It was found that the fluoride release from the subgroups of giomer and compomer was in the following order: fluoridated dentifrice twice daily > fluoridated dentifrice once daily + fluoridated mouthwash > fluoridated dentifrice once daily > control group. It was found that the giomer showed a greater fluoride uptake than the compomer.

3' Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] by voltage-sensing phosphatase (VSP).

Science.gov (United States)

Kurokawa, Tatsuki; Takasuga, Shunsuke; Sakata, Souhei; Yamaguchi, Shinji; Horie, Shigeo; Homma, Koichi J; Sasaki, Takehiko; Okamura, Yasushi

2012-06-19

Voltage-sensing phosphatases (VSPs) consist of a voltage-sensor domain and a cytoplasmic region with remarkable sequence similarity to phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a tumor suppressor phosphatase. VSPs dephosphorylate the 5' position of the inositol ring of both phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P(3)] and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)] upon voltage depolarization. However, it is unclear whether VSPs also have 3' phosphatase activity. To gain insights into this question, we performed in vitro assays of phosphatase activities of Ciona intestinalis VSP (Ci-VSP) and transmembrane phosphatase with tensin homology (TPTE) and PTEN homologous inositol lipid phosphatase (TPIP; one human ortholog of VSP) with radiolabeled PI(3,4,5)P(3). TLC assay showed that the 3' phosphate of PI(3,4,5)P(3) was not dephosphorylated, whereas that of phosphatidylinositol 3,4-bisphosphate [PI(3,4)P(2)] was removed by VSPs. Monitoring of PI(3,4)P(2) levels with the pleckstrin homology (PH) domain from tandem PH domain-containing protein (TAPP1) fused with GFP (PH(TAPP1)-GFP) by confocal microscopy in amphibian oocytes showed an increase of fluorescence intensity during depolarization to 0 mV, consistent with 5' phosphatase activity of VSP toward PI(3,4,5)P(3). However, depolarization to 60 mV showed a transient increase of GFP fluorescence followed by a decrease, indicating that, after PI(3,4,5)P(3) is dephosphorylated at the 5' position, PI(3,4)P(2) is then dephosphorylated at the 3' position. These results suggest that substrate specificity of the VSP changes with membrane potential.

Chronic fluoride toxicity: dental fluorosis.

Science.gov (United States)

Denbesten, Pamela; Li, Wu

2011-01-01

Dental fluorosis occurs as a result of excess fluoride ingestion during tooth formation. Enamel fluorosis and primary dentin fluorosis can only occur when teeth are forming, and therefore fluoride exposure (as it relates to dental fluorosis) occurs during childhood. In the permanent dentition, this would begin with the lower incisors, which complete mineralization at approximately 2-3 years of age, and end after mineralization of the third molars. The white opaque appearance of fluorosed enamel is caused by a hypomineralized enamel subsurface. With more severe dental fluorosis, pitting and a loss of the enamel surface occurs, leading to secondary staining (appearing as a brown color). Many of the changes caused by fluoride are related to cell/matrix interactions as the teeth are forming. At the early maturation stage, the relative quantity of amelogenin protein is increased in fluorosed enamel in a dose-related manner. This appears to result from a delay in the removal of amelogenins as the enamel matures. In vitro, when fluoride is incorporated into the mineral, more protein binds to the forming mineral, and protein removal by proteinases is delayed. This suggests that altered protein/mineral interactions are in part responsible for retention of amelogenins and the resultant hypomineralization that occurs in fluorosed enamel. Fluoride also appears to enhance mineral precipitation in forming teeth, resulting in hypermineralized bands of enamel, which are then followed by hypomineralized bands. Enhanced mineral precipitation with local increases in matrix acidity may affect maturation stage ameloblast modulation, potentially explaining the dose-related decrease in cycles of ameloblast modulation from ruffle-ended to smooth-ended cells that occur with fluoride exposure in rodents. Specific cellular effects of fluoride have been implicated, but more research is needed to determine which of these changes are relevant to the formation of fluorosed teeth. As further

Is HO3 minimum cis or trans? An analytic full-dimensional ab initio isomerization path.

Science.gov (United States)

Varandas, A J C

2011-05-28

The minimum energy path for isomerization of HO(3) has been explored in detail using accurate high-level ab initio methods and techniques for extrapolation to the complete basis set limit. In agreement with other reports, the best estimates from both valence-only and all-electron single-reference methods here utilized predict the minimum of the cis-HO(3) isomer to be deeper than the trans-HO(3) one. They also show that the energy varies by less than 1 kcal mol(-1) or so over the full isomerization path. A similar result is found from valence-only multireference configuration interaction calculations with the size-extensive Davidson correction and a correlation consistent triple-zeta basis, which predict the energy difference between the two isomers to be of only Δ = -0.1 kcal mol(-1). However, single-point multireference calculations carried out at the optimum triple-zeta geometry with basis sets of the correlation consistent family but cardinal numbers up to X = 6 lead upon a dual-level extrapolation to the complete basis set limit of Δ = (0.12 ± 0.05) kcal mol(-1). In turn, extrapolations with the all-electron single-reference coupled-cluster method including the perturbative triples correction yield values of Δ = -0.19 and -0.03 kcal mol(-1) when done from triple-quadruple and quadruple-quintuple zeta pairs with two basis sets of increasing quality, namely cc-cpVXZ and aug-cc-pVXZ. Yet, if added a value of 0.25 kcal mol(-1) that accounts for the effect of triple and perturbative quadruple excitations with the VTZ basis set, one obtains a coupled cluster estimate of Δ = (0.14 ± 0.08) kcal mol(-1). It is then shown for the first time from systematic ab initio calculations that the trans-HO(3) isomer is more stable than the cis one, in agreement with the available experimental evidence. Inclusion of the best reported zero-point energy difference (0.382 kcal mol(-1)) from multireference configuration interaction calculations enhances further the relative

Stabilization of fluoroindate glasses by magnesium fluoride and other heavy metal fluorides

Directory of Open Access Journals (Sweden)

B. J. Costa

1998-06-01

Full Text Available Their extended transparency in the IR makes them attractive for use as optical fibers for CO laser power delivery and optical amplification. This paper firstly describes the spectacular stabilizing effect of MgF2 on the binary system InF3-BaF2. The investigation of the InF3-BaF2-MgF2 system led to samples up to 5mm in thickness. Further optimization of this system was achieved by incorporation of limited amounts of other fluorides and resulted in increased resistence to devitrification. The second approach of this work was concerned to the investigation of the pseudo-ternary system InF3-GdF3-GaF3 at constant concentrations of ZnF2-SrF2-BaF2-NaF. Several compositions were studied in this system. The samples presented a better thermal stability when compared to other families of fluoride glasses. Therefore, these glasses seem to be very promising for the fabrication of special optical fibers. Thermal data are reported.

Fluoride analysis

Energy Technology Data Exchange (ETDEWEB)

Brandt, C S

1963-01-01

The methods and procedures for the detection and estimation of fluoride are varied and numerous. The problems of sampling, contamination, and loss in sampling waters, plant and animal tissues and atmospheres are discussed, along with brief descriptors of methods most commonly used. Techniques for separating fluorides from matrixes are discussed, as well as gravimetric, calorimetric, and spectrophotometric analytical techniques.

Story of Fluoridation

Science.gov (United States)

... Home Health Info Health Topics Fluoride Share The Story of Fluoridation It started as an observation, that ... this time using photospectrographic analysis, a more sophisticated technology than that used by McKay. Churchill asked an ...

Labeling of biotin with 166Dy/166Ho as a stable in vivo generator system

International Nuclear Information System (INIS)

Ferro-Flores, G.; Monroy-Guzman, F.; Tendilla, J.I.; Garcia-Salinas, L.; Villarreal-Barajas, J.E.; Arteaga-Murphy, C.

2002-01-01

Biotin (cis-tetrahydro-2-oxothieno[3,4-d]imidazoline-4-valeric acid) is a 244 Da vitamin found in low concentration in blood and tissue (vitamin H). The aim of this work was to synthesize 166 Dy/ 166 Ho-DTPA-bisBiotin to evaluate its potential as a new radiopharmaceutical for targeted radiotherapy. Dysprosium-166/ holmium-166 chloride was obtained by neutron irradiation of 20 mg of enriched Dy 2 O 3 ( 164 Dy, 99 %, from Oak Ridge NL) in a Triga Mark III reactor at a flux in the central thimble of 3.10 13 n. cm -2 s -1 for 20 h. Following irradiation, the target was allowed to decay for 2 days, then 100 μL of 12 N chloride acid were added and stirred for 1 min. To this solution was added 500 μL of injectable water and the whole was also stirred for 2 min. The average radioactive concentration was 332 MBq/ml. The biotin used in this investigation was covalently conjugated to diethylenetriamine pentaacetic acid (DTPA) through the use of the cyclic anhydride and lysine conjugate to biotin (biocytin) to produce DTPA-α,ω-bis(biocytin amide)(DTPA-bisBiotin). Sterile and apyrogenic V-vial was prepared to contain 2.0 mg (1.9 x 10 -3 mmol) of the DTPA-bisbiotin compound in 1.0 ml of 0.05 M bicarbonate buffer (pH 8.0) and then 20 μL of 166 Dy2Cl3 solution were added to the preparation. Thin Layer Chromatography aluminum cellulose sheets were utilised as the stationary phase and a ternary mixture of methanol:water:ammonium hydroxide (20:40:2) as the mobile phase. 166 Dy/ 166 Ho-DTPA-bisBiotin travelled with the solvent front R f 0.9-1.0 and the Dy +3 /Ho +3 species remained at the origin (R f = 0). The biological integrity of labelled biotin was achieved evaluating its avidity for avidin in an agarose column. Stability studies against dilution were carried out by diluting the radiocomplex solution with saline and with human serum at 310 K. After 10 min and 24 h the radiochemical purity of each 166 Dy/ 166 Ho complex solution was determined by TLC. The complex 166 Dy/ 166

Production, Quality Control and Biological Evaluation of 166Ho-PDTMP as a Possible Bone Palliation Agent

Directory of Open Access Journals (Sweden)

Samaneh Zolghadri

2013-05-01

Full Text Available Objective(s:In this study, 166Ho-1,2-propylene di-amino tetra(methy1enephosphonicAcid (166Ho-PDTMP complex  was prepared as a bone palliation agent. Materials and Methods:The complex was successfully prepared using an in-house synthesized EDTMP ligand and 166HoCl3. Ho-166 chloride was obtained by thermal neutron irradiation (1 × 1013 n.cm-2.s-1 of natural Ho(NO33 samples  followed by radiolabeling and stability studies. Biodistribution in wild type rats was also peformed. Results: The complex was prepared with thespecific activity of 278 GBq/mg and high radiochemical purity (>99%, checked by ITLC. 166Ho-PDTMP complex was stabilized in the final preparation and in the presence of human serum (>90% up to 72 hr. The biodistribution of 166Ho-PDTMP in wild-type rats demonstrated significant bone uptake was up to 48 hr compared to 166HoCl3. Conclusion: The produced 166Ho-PDTMP properties suggest a possible new bone palliative therapeutic to overcome the metastatic bone pains.  

Private Well Water and Fluoride

Science.gov (United States)

... Private Wells Infant Formula Fluorosis Public Health Service Recommendation Water Operators & Engineers Water Fluoridation Additives Shortages of Fluoridation Additives Drinking Water Pipe Systems CDC-Sponsored Water Fluoridation Training Links to Other ...

Short term serum pharmacokinetics of diammine silver fluoride after oral application.

Science.gov (United States)

Vasquez, Elsa; Zegarra, Graciela; Chirinos, Edgar; Castillo, Jorge L; Taves, Donald R; Watson, Gene E; Dills, Russell; Mancl, Lloyd L; Milgrom, Peter

2012-12-31

There is growing interest in the use of diammine silver fluoride (DSF) as a topical agent to treat dentin hypersensitivity and dental caries as gauged by increasing published research from many parts of the world. While DSF has been available in various formulations for many years, most of its pharmacokinetic aspects within the therapeutic concentration range have never been fully characterized. This preliminary study determined the applied doses (3 teeth treated), maximum serum concentrations, and time to maximum serum concentration for fluoride and silver in 6 adults over 4 h. Fluoride was determined using the indirect diffusion method with a fluoride selective electrode, and silver was determined using inductively coupled plasma-mass spectrometry. The mean amount of DSF solution applied to the 3 teeth was 7.57 mg (6.04 μL). Over the 4 hour observation period, the mean maximum serum concentrations were 1.86 μmol/L for fluoride and 206 nmol/L for silver. These maximums were reached 3.0 h and 2.5 h for fluoride and silver, respectively. Fluoride exposure was below the U.S. Environmental Protection Agency (EPA) oral reference dose. Silver exposure exceeded the EPA oral reference dose for cumulative daily exposure over a lifetime, but for occasional use was well below concentrations associated with toxicity. This preliminary study suggests that serum concentrations of fluoride and silver after topical application of DSF should pose little toxicity risk when used in adults. NCT01664871.

Fluoride release and recharge behavior of a nano-filled resin-modified glass ionomer compared with that of other fluoride releasing materials.

Science.gov (United States)

Mitra, Sumita B; Oxman, Joe D; Falsafi, Afshin; Ton, Tiffany T

2011-12-01

To compare the long-term fluoride release kinetics of a novel nano-filled two-paste resin-modified glass-ionomer (RMGI), Ketac Nano (KN) with that of two powder-liquid resin-modified glass-ionomers, Fuji II LC (FLC) and Vitremer (VT) and one conventional glass-ionomer, Fuji IX (FIX). Fluoride release was measured in vitro using ion-selective electrodes. Kinetic analysis was done using regression analysis and compared with existing models for GIs and compomers. In a separate experiment the samples of KN and two conventional glass-ionomers, FIX and Ketac Molar (KM) were subjected to a treatment with external fluoride source (Oral-B Neutra-Foam) after 3 months of fluoride release and the recharge behavior studied for an additional 7-day period. The cumulative amount of fluoride released from KN, VT and FLC and the release profiles were statistically similar but greater than that for FIX at P coating of KN with its primer and of DY with its adhesive did not significantly alter the fluoride release behavior of the respective materials. The overall rate for KN was significantly higher than for the compomer DY. DY showed a linear rate of release vs. t and no burst effect as expected for compomers. The nanoionomer KN showed fluoride recharge behavior similar to the conventional glass ionomers FIX and KM. Thus, it was concluded that the new RMGI KN exhibits fluoride ion release behavior similar to typical conventional and RMGIs and that the primer does not impede the release of fluoride.

Fluoride in diet

Science.gov (United States)

Diet - fluoride ... bones and teeth. Too much fluoride in the diet is very rare. Rarely, infants who get too ... of essential vitamins is to eat a balanced diet that contains a variety of foods from the ...

Low temperature fluorination of Sr3Fe2O7−x with polyvinylidine fluoride: An X-ray powder diffraction and Mössbauer spectroscopy study

International Nuclear Information System (INIS)

Hancock, Cathryn A.; Herranz, Tirma; Marco, Jose F.; Berry, Frank J.; Slater, Peter R.

2012-01-01

Fluorination of the Ruddlesden Popper phase, Sr 3 Fe 2 O 7−x by heat treatment with polyvinylidine fluoride (PVDF) gives a range of novel oxide fluoride compounds. Fluorination with 1 mol equivalent PVDF leads to a filling of the normal Ruddlesden Popper structure anion sites and a material of composition Sr 3 Fe 2 O 5+x F 2−x (x≈0.28(4)) which contains both Fe 4+ and Fe 3+ . Increasing the amount of PVDF to 2 mol equivalent leads to an increase in anion content due to filling of half the interstitial sites within the structure, with iron being completely reduced to Fe 3+ leading to a composition Sr 3 Fe 2 O 4 F 4 . An increase in the amount of PVDF to ≈3 mol equivalent leads to a further increase in unit cell volume, attributed to complete filling of the interstitial sites and a composition Sr 3 Fe 2 O 3 F 6 . 57 Fe Mössbauer spectra in the temperature range 10–300 K demonstrated the complexity of the magnetic interactions in each of the three phases which reflect different local compositions of oxygen and fluorine around the iron ions thus influencing the superexchange pathways. - Graphical abstract: Low temperature (375 °C) fluorination of Sr 3 Fe 2 O 7−x with poly(vinylidene fluoride) leads to the production of three new Ruddlesden Popper oxide fluorides with progressive filling of the anion sites within the structure. Highlights: ► The fluorination of Sr 3 Fe 2 O 7−x using PVDF. ► The control of the fluorine content with amount of PVDF used. ► The synthesis of three new Fe based oxide fluorides. ► The identification of the structures of these oxide fluorides.

36 W Q-switched Ho:YAG laser at 2097 nm pumped by a Tm fiber laser: evaluation of different Ho3+ doping concentrations

Science.gov (United States)

Antipov, O. L.; Eranov, I. D.; Kositsyn, R. I.

2017-01-01

A laser oscillator based on Ho:YAG crystal pumped by a Tm fiber laser with an acousto-optical Q-switch was optimized for maximum output power and pulse-to-pulse stability. Stable operation at 2097 nm in Q-switched mode is demonstrated, with pulse repetition rates from 10 to 30 kHz, and output power of 36 W (at 55 W of pump power at 1908 nm) in the good quality beam. The influence of Ho ion up-conversion and thermal lensing on the oscillation efficiency is discussed.

Different diffusion mechanisms of oxygen in ReBa{sub 2}Cu{sub 3}O{sub 7−x} (Re = Y, Ho) single crystals

Energy Technology Data Exchange (ETDEWEB)

Vovk, R.V.; Boiko, Y.I.; Bogdanov, V.V.; Kamchatnaya, S.N.; Goulatis, I.L. [V. N. Karazin Kharkiv National University, 4 Svobody sq., 61077 Kharkiv (Ukraine); Chroneos, A. [Faculty of Engineering, Environment and Computing, Coventry University, Priory Street, Coventry CV1 5FB (United Kingdom); Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom)

2017-05-15

Highlights: • Single file diffusion mechanism of oxygen ions. • Ho modifies the diffusion mechanism in the oxygen sublattice. • Ho changes the efficient interaction of ions in CuO-planes. - Abstract: In the present study, the time dependencies of the resistivity of ReBa{sub 2}Cu{sub 3}O{sub 7−x} (Re=Y, Ho) single crystals with varying degree of deviation from oxygen stoichiometry was investigated. It was shown that the accelerated transport of oxygen ions in the initial stage of the process can be carried out along the one-dimensional non-stoichiometric vacancies’ accumulation by the single file diffusion mechanism. The final phase redistribution of oxygen ions in ReBa{sub 2}Cu{sub 3}O{sub 7−x} (Re = Y, Ho) is described by the classical mechanism of volume diffusion. The substitution of yttrium by holmium significantly affects the charge redistribution and changes the efficient interaction of ions in CuO-planes, thereby modifying the mass transfer diffusion mechanisms in the oxygen sublattice. Thus, a significant length change of the time intervals occurs, corresponding to the oxygen ions’ single file and volume diffusion mechanisms.

An In-Vitro Study on the Release of Fluoride from Two Restorative Materials and Their Rechargeability after Exposure to Daily 1000 ppm Fluoride

Directory of Open Access Journals (Sweden)

A. Kowsari

2005-09-01

Full Text Available Statement of Problem: Since the fluoride releases from materials with the property of releasing fluoride are decreasing gradually, it seems that probably the material rechargeability is more important than their long-term fluoride release.Purpose: the objective of this study was to asses the fluoride release and rechargeability of 2 types of fluoride releasing restorative materials, a resin modified glass ionomer(Vitremer and a compomer (Compoglass F, after exposure to daily NaF solutionscontaining 1000 ppm F, for 1 minute.Materials and Methods: Twelve discs ( 8 mm ×2 mm of each of the materials were fabricated, and divided into 2 groups (test and control. All discs were stored in 4 mL artificial saliva at 37°C. In group 1 (N=6, the specimens were immersed in artificialsaliva which was changed daily for 25 days. In group 2 (N=6, in addition to receiving the same treatment as group 1, the specimens were immersed in NaF solution (1000ppm F, ph=6.9 for 1 minute before daily saliva change. A potentiometer was used to determine the amount of fluoride released on days 1, 2, 3, 5, 10, 15, 20 and 25, after the daily saliva change, in all study groups. Data were analyzed by the t-student test after confirmation of the equality of variances by Leven’s test.Results: Both materials continued releasing fluoride throughout the whole study period. For each material, the release was highest on day one. During the first 3 days,glass ionomer released significantly higher amounts of fluoride as compared to compomer (p0.05. After exposure to NaF solution, none of the materials showed statistically significant rechargeability (p>0.05 and the amount of fluoride-releasecontinued to drop during the study period in similar patterns for both the test and the control groups.Conclusion: It may be concluded that rechargeability of glass ionomer and compomer,using daily neutral fluoride mouth rinses and toothpastes does not occur in reliable amounts.

Application of a new adsorbent for fluoride removal from aqueous solutions

International Nuclear Information System (INIS)

Srivastav, Arun Lal; Singh, Prabhat K.; Srivastava, Varsha; Sharma, Yogesh C.

2013-01-01

Highlights: • A new adsorbent has been prepared. • The adsorbent is non-toxic and easy to synthesize. • HBO 1 has displayed best capacity for the removal of fluoride. • Unlike most adsorbents, HBO 1 is suitable for the removal of fluoride from water. • The process of removal has been optimized. -- Abstract: Hydrous bismuth oxides (HBOs) have been investigated as a possible adsorbent for fluoride removal from water. Apart from bismuth trioxide (Bi 2 O 3 ) compound, three additional HBOs, named as HBO 1 , HBO 2 , and HBO 3 were synthesized in the laboratory and examined for their relative potentials for fluoride removal from aqueous solutions. HBO 1 was observed to have highest fluoride removal at 10 mg/L initial concentration in aqueous environment. Among competitive anions, sulfate and chloride affect the fluoride removal by HBO 1 more adversely than bicarbonate. Characterization of HBOs using X-ray diffraction (XRD) pattern analyses indicated crystalline structures, and the broad chemical composition of materials showed successive increase of Bi(OH) 3 from HBO 1 to HBO 3 , with decrease of BiOCl in the same order. Fourier Transform Infrared (FTIR) spectroscopy analyses indicated presence of Bi-O bond and successively increasing number of peaks corresponding to OH ion from HBO 1 to HBO 3 . Scanning Electron Microscopic (SEM) images of HBOs show rough and porous structure of the materials. Presence of higher proportion of chloride compound in HBO 1 with respect to others appears to be the factor responsible for its better performance in fluoride removal from aqueous solutions

Growth, spectroscopy and laser operation of Ho:KY(WO{sub 4}){sub 2}

Energy Technology Data Exchange (ETDEWEB)

Jambunathan, V. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); HiLASE Centre, Institute of Physics ASCR, Za Radnicí 828, 25241 Dolní Břežany (Czech Republic); Mateos, X., E-mail: xavier.mateos@urv.cat [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., D-12489 Berlin (Germany); Loiko, P.A. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., 220013 Minsk (Belarus); Serres, J.M. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); Griebner, U.; Petrov, V. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., D-12489 Berlin (Germany); Yumashev, K.V. [Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., 220013 Minsk (Belarus); and others

2016-11-15

Monoclinic Ho:KY(WO{sub 4}){sub 2} crystals doped with up to 7.5 at.% Ho are grown by the Top Seeded Solution Growth-Slow Cooling method. The evolution of their unit cell parameters in dependence on the Ho doping and temperature is studied. The polarized low-temperature (6 K) optical absorption of the Ho{sup 3+} ion is investigated in detail to determine the energy of the Stark sub-levels. Room-temperature absorption, stimulated-emission and gain cross-section spectra of Ho:KY(WO{sub 4}){sub 2} crystals are derived for polarizations parallel to the principal optical axes, E||N{sub p}, N{sub m} and N{sub g}. The maximum absorption cross-section for the {sup 5}I{sub 8}→{sup 5}I{sub 7} transition is 1.60×10{sup −20} cm{sup 2} at 1961.0 nm and the maximum stimulated-emission cross-section for the {sup 5}I{sub 7}→{sup 5}I{sub 8} transition is 2.65×10{sup −20} cm{sup 2} at 2056.3 nm (for E||N{sub m}). The radiative lifetime of the upper laser level of the Ho{sup 3+} ion ({sup 5}I{sub 7}) amounts to 4.8 ms. Continuous-wave Ho{sup 3+} laser operation is achieved under in-band pumping by a Tm laser at 1946 nm. In the microchip configuration, the maximum output power reached 205 mW at 2105 nm with a slope efficiency as high as 85%.

Study on preparation of 166Ho-Chitosan oriented in the treatment of liver cancer

International Nuclear Information System (INIS)

Dang Ho Hong Quang; Duong Van Dong; Bui Van Cuong; Nguyen Thanh Binh; Nguyen Thanh Nhan; Nguyen Dinh Lam; Nguyen Thi Thu

2017-01-01

This study describes the process for the preparation and quality control of 166 Ho-Chitosan product. The labeling conditions of chitosan with 166 Ho radioisotope were carried out such as the concentration of chitosan, pH, temperature and reaction time to create 166 Ho-Chitosan compositions. Product quality inspection 166 Ho-Chitosan on the criteria as nuclide purity, radiochemical purity, tested for sterility and bacterial endotoxin. The results of survey showed that 166 Ho labeled with chitosan were completed in 1% acetic acid, 3 mCi: 30 mg ratio at pH = 3, marking time at room temperature for 30 minutes. The results of quality test have shown radionuclide purity ≥ 99%, radiochemical purity ≥ 98%, meeting the criteria for the aseptic and bacterial endotoxin according to IV Vietnam pharmacopoeia. From the above mentioned, 166 Ho-Chitosan compositions meet the quality criteria of the radiopharmaceuticals, therefore, it can be used in pre-clinical research and its application in clinical treatment. (author)

An in situ caries study on the interplay between fluoride dose and concentration in milk.

Science.gov (United States)

Lippert, F; Martinez-Mier, E A; Zero, D T

2014-07-01

This randomized, cross-over in situ study investigated the impact of sodium fluoride dose and concentration in milk on caries lesion rehardening, fluoridation and acid resistance. Twenty-eight subjects wore two gauze-covered enamel specimens with preformed lesions placed buccally on their mandibular partial dentures for three weeks. Participants used fluoride-free dentifrice throughout the study and consumed once daily one of the five study treatments: no fluoride in 200 ml milk (0F-200), 1.5 or 3 mg fluoride in either 100 (1.5F-100; 3F-100) or 200 ml milk (1.5F-200; 3F-200). After three weeks, specimens were retrieved. Knoop hardness was used to determine rehardening and resistance to a secondary acid challenge. Enamel fluoride uptake (EFU) was determined using a microbiopsy technique. A linear fluoride dose-response was observed for all study variables which exhibited similar overall patterns. All the treatments resulted in rehardening, with 0F-200 inducing the least and 3F-100 the most. Apart from 1.5F-200, all the treatments resulted in statistically significantly more rehardening compared to 0F-200. The fluoride doses delivered in 100 ml provided directionally although not statistically significantly more rehardening than those delivered in 200 ml milk. EFU data exhibited better differentiation between treatments: all fluoridated milk treatments delivered more fluoride to lesions than 0F-200; fluoride in 100 ml demonstrated statistically significantly higher EFU than fluoride in 200 ml milk. Findings for acid resistance were also more discerning than rehardening data. The present study has provided further evidence for the anti-caries benefits of fluoridated milk. Both fluoride dose and concentration appear to impact the cariostatic properties of fluoride in milk. Copyright © 2014 Elsevier Ltd. All rights reserved.

A single crystal study of RE{sub 14}Co{sub 3}In{sub 3} (RE = Y, Tb, Dy, Ho, Er)

Energy Technology Data Exchange (ETDEWEB)

Zaremba, V.I.; Kalychak, Y.M.; Dzevenko, M.V. [Inorganic Chemistry Dept., Ivan Franko National Univ. of Lviv (Ukraine); Rodewald, U.Ch.; Heying, B.; Poettgen, R. [Inst. fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Univ. Muenster (Germany)

2006-01-01

The rare earth-cobalt-indides RE{sub 14}Co{sub 3}In{sub 3} (RE = Y, Tb, Dy, Ho, Er) were prepared in polycrystalline form from the elements by arc-melting. Small single crystals were grown through a special annealing sequence. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu{sub 14}Co{sub 2}In{sub 3} (Gd{sub 14}Co{sub 3}In{sub 2.7}) type, P4{sub 2}/nmc, Z = 4, a = 959.0(1), c = 2319.1(5) pm, wR2 = 0.055, 2289 F{sup 2} values, 65 variables for Y{sub 13.90}Co{sub 2.99}In{sub 3.02}, a = 953.8(1), c = 2315.8(5) pm, wR2 = 0.108, 2357 F{sup 2} values, 65 variables for Tb{sub 13.92}Co{sub 3.01}In{sub 2.92}, a = 949.24(3), c = 2296.5(1) pm, wR2 = 0.129, 2518 F{sup 2} values, 65 variables for Dy{sub 13.90}Co{sub 2.97}In{sub 2.95}, a = 946.3(1), c = 2289.0(5) pm, wR2 = 0.099, 2297 F{sup 2} values, 64 variables for Ho{sub 14}Co{sub 2.80}In{sub 2.89}, and a = 941.0(1), c = 2274.2(5) pm, wR2 = 0.140, 2450 F{sup 2} values, 65 variables for Er{sub 13.83}Co{sub 2.88}In{sub 3.10}. All RE{sub 14}Co{sub 3}In{sub 3} indides show a small degree of In/Co mixing (between 7 and 16% Co) on the 4c In1 site and defects on the 8g Co1 positions (between 84 and 95% Co). Except for the holmium compound, the RE{sub 14}Co{sub 3}In{sub 3} intermetallics also reveal RE/In mixing on the 4c RE1 sites, leading to the refined compositions. The seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE{sub 14}Co{sub 3}In{sub 3} structures consist of a complex intergrowth of rare earth based polyhedra. Both cobalt sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2-In2 dumb-bell with an In2-In2 distance of 300 pm (for Ho{sub 14}Co{sub 2.80}In{sub 2.89}). The crystal chemistry of the RE{sub 14}Co{sub 3}In{sub 3} indides is discussed. (orig.)

Protection From Dental Erosion: All Fluorides are Not Equal.

Science.gov (United States)

Faller, Robert V; Noble, Warden H

2018-03-01

All fluoride sources help strengthen teeth against bacterial acids that cause caries. However, excessive exposure to dietary acids, which can result in dental erosion, presents a more aggressive level of challenge compared to caries. Despite the fact that almost all toothpastes contain fluoride, both the incidence and prevalence of dental erosion appear to be on the rise. This article: (1) describes key differences between caries and dental erosion and the ability of different fluoride sources to help prevent erosion; (2) discusses the importance of the evaluation of patients for dental erosion at the earliest stages using the Basic Erosive Wear Examination scoring system to help assess and educate patients; and (3) provides evidence-based information for making specific recommendations to patients with dental erosion. The objective of this article is to assess the comparative ability of fluoride agents to protect against dental erosion. Though all fluorides are able to help strengthen teeth against cariogenic acids, not all available sources of fluoride provide the same level of erosion protection. Daily use of a stabilized stannous fluoride dentifrice has been shown to provide the most effective means of protecting teeth against the increasing risk of dental erosion and erosive tooth wear.

The effect of supplementation of calcium, vitamin D, boron, and increased fluoride intake on bone mechanical properties and metabolic hormones in rat.

Science.gov (United States)

Ghanizadeh, G; Babaei, M; Naghii, Mohammad Reza; Mofid, M; Torkaman, G; Hedayati, M

2014-04-01

Evidence indicates that optimal nutrition plays a role in bone formation and maintenance. Besides major components of mineralization such as calcium, phosphorus, and vitamin D, other nutrients like boron and fluoride have beneficial role, too. In this study, 34 male Wistar rats were divided into five groups: control diet, fluoride, fluoride + boron, fluoride + calcium + vitamin D, and fluoride + boron + calcium + vitamin D. Boron equal to 1.23 mg, calcium and vitamin D equal to 210 mg + 55 IU and fluoride equal to 0.7 mg/rat/day was added to their drinking water for 8 weeks. Plasma blood samples and bones were collected. Findings are evidence that fluoride + boron intake revealed significant positive effects on bone mechanical properties and bone metabolic hormones. These findings suggest that combined intake of these two elements has beneficial effects on bone stiffness and breaking strength comparing to even calcium + vitamin D supplementation. This evidence dealing with health problems related to bone and skeletal system in humans should justify further investigation of the role of boron and fluoride with other elements in relation to bone.

Determination of the stability constants of a number of metal fluoride complexes and their rates of formation

International Nuclear Information System (INIS)

Hammer, R.R.

1979-08-01

The stability constants of the fluoride complexes of Al +3 , H 3 BO 3 , Cr +3 , Cr +6 , Fe +3 , Gd +3 , Nb +5 , UO 2 +2 , and Zr +4 were determined in 0.96 and 2.88 M HNO 3 solutions in the temperature range 25 to 60 0 C with a fluoride specific ion electrode. These data can be used to calculate the concentration of chemical species in solution and will be used to correlate solution properties with solution composition. The solubilities of some fluoride precipitates were also measured in nitric acid solutions. The rates of formation of the fluoborates, aluminum fluoride, and zirconium fluoride complexes were measured with a fluoride specific ion electrode at 25, 35, and 45 0 C. The rates of formation of all complexes, except BF 4 - , AlF +2 , and a fluoride complex with aluminum containing more than three fluorides associated with it, were too fast to measure with the instrumentation used

Řízení procesu reaktivního magnetronového naprašování

OpenAIRE

Dušek, Jan

2014-01-01

Bakalářská práce stručně popisuje technologii reaktivního magnetronového naprašování a zabývá se návrhem a realizací programu k jeho ovládání. K tomuto účelu byl vytvořen ovládací program pro řízení jednotlivých komponent aparatury PLS160 v programovacím prostředí LabView. Na základě znalostí technologického procesu a postupu reaktivního magnetronového naprašování byl vytvořen automatický program. Tento automatický program je možné modifikovat pomocí receptů. Vedle programové skladby byly pro...

Modification of radiation effect by sodium fluoride in Tradescantia

International Nuclear Information System (INIS)

Cebulska-Wasilewska, A.; Guminska, M.; Huczkowski, J.; Kuternozinska, W.

1988-01-01

Frequency of somatic mutations in the Tradescantia stamen hairs served as a measure of biological effect of gamma irradiation with single and split doses and of modifications caused by sodium fluoride. It was found that treatment of plants with fluoride before irradiation affects considerably radiation-induced mutations. The changed peak mutation frequency in plants treated with fluoride suggests that it vitally influences the repair processes of DNA and possibly modifies the mutation spectrum. 14 refs., 3 figs. (author)

Measurement of transvers spin effects by means of two-hadron correlations in the COMPASS experiment; Messung transversaler Spineffekte mittels zwei Hadronen Korrelation am COMPASS-Experiment

Energy Technology Data Exchange (ETDEWEB)

Massmann, Frank Michael

2008-06-23

Helizitaets- Verteilungsfunktion {delta}q(x) und die transversale Quarkspin Verteilungsfunktion {delta}{sub T}q(x). Diese letztgenannte Funktion, genannt ''Transversity'' Funktion, ist chiral ungerade und kann deshalb nur in Kombination mit einer anderen chiral ungeraden Funktion gemessen werden. Eine Zugangsmoeglichkeit zur ''Transversity'' Funktion {delta}{sub T}q(x) ist die semi-inklusive zwei Hadronenproduktion in tief inelastischer Streuung an einem transversal polarisierten Target. Dabei misst man die Faltung der chiral ungeraden zwei Hadronen Interferenz Fragmentationsfunktion (IFF) H{sub 1} {sup angle} (z,M{sub h}{sup 2}) und der chiral ungeraden ''Transversity'' Funktion. Die IFF H{sub 1} {sup angle} (z,M{sub h}{sup 2}) ist der spinabhaengige Teil einer Fragmentationsfunktion, die die Fragmentation eines transversal polarisierten Quarks in zwei unpolarisierte Hadronen beschreibt. Die Produktion der zwei Hadronen erfolgt in einer Interferenz zwischen verschiedenen Wellenzustaenden der Hadronenpaare. Man misst azimuthale Asymmetrien in den erzeugten Hadronenpaaren. Die Messungen, die in dieser Arbeit beschrieben werden, wurden am COMPASS Experiment am CERN in den Jahren 2002-2004 durchgefuehrt, welches ein Feststoff Target Experiment am SPS Beschleuniger ist. Nach einer Einfuehrung werden in Kapitel 2 die zugrundeliegenden theoretischen Konzepte zur Messung der ''Transversity'' Funktion vorgestellt. In Kapitel 3 wird das COMPASS Experiment beschrieben. Schliesslich werden in Kapitel 4 die Auswertemethoden besprochen, die Ergebnisse der azimuthalen Asymmetrien gezeigt und mit theoretischen Vorhersagen verglichen. (orig.)

Physiology and toxicity of fluoride

Directory of Open Access Journals (Sweden)

Dhar Vineet

2009-01-01

Full Text Available Fluoride has been described as an essential element needed for normal development and growth of animals and extremely useful for human beings. Fluoride is abundant in the environment and the main source of fluoride to humans is drinking water. It has been proved to be beneficial in recommended doses, and at the same time its toxicity at higher levels has also been well established. Fluoride gets accumulated in hard tissues of the body and has been know to play an important role in mineralization of bone and teeth. At high levels it has been known to cause dental and skeletal fluorosis. There are suggested effects of very high levels of fluoride on various body organs and genetic material. The purpose of this paper is to review the various aspects of fluoride and its importance in human life.

Physiology and toxicity of fluoride.

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Dhar, Vineet; Bhatnagar, Maheep

2009-01-01

Fluoride has been described as an essential element needed for normal development and growth of animals and extremely useful for human beings. Fluoride is abundant in the environment and the main source of fluoride to humans is drinking water. It has been proved to be beneficial in recommended doses, and at the same time its toxicity at higher levels has also been well established. Fluoride gets accumulated in hard tissues of the body and has been know to play an important role in mineralization of bone and teeth. At high levels it has been known to cause dental and skeletal fluorosis. There are suggested effects of very high levels of fluoride on various body organs and genetic material. The purpose of this paper is to review the various aspects of fluoride and its importance in human life.

Fluoride barriers in Nb/Pb Josephson junctions

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Asano, H.; Tanabe, K.; Michikami, O.; Igarashi, M.; Beasley, M. R.

1985-03-01

Josephson tunnel junctions are fabricated using a new class of artificial barriers, metal fluorides (Al fluoride and Zr fluoride). These fluoride barriers are deposited on the surface of a Nb base electrode, which are previously cleaned using a CF4 cleaning process, and covered by a Pb counterelectrode. The junctions with both Al fluoride and Zr fluoride barriers exhibit good tunneling characteristics and have low specific capacitance. In the case of Zr fluoride, it is observed that reasonable resistances are obtained even at thickness greater than 100 A. This phenomenon might be explained by tunneling via localized states in Zr fluoride.

Short term serum pharmacokinetics of diammine silver fluoride after oral application

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Vasquez Elsa

2012-12-01

Full Text Available Abstract Background There is growing interest in the use of diammine silver fluoride (DSF as a topical agent to treat dentin hypersensitivity and dental caries as gauged by increasing published research from many parts of the world. While DSF has been available in various formulations for many years, most of its pharmacokinetic aspects within the therapeutic concentration range have never been fully characterized. Methods This preliminary study determined the applied doses (3 teeth treated, maximum serum concentrations, and time to maximum serum concentration for fluoride and silver in 6 adults over 4 h. Fluoride was determined using the indirect diffusion method with a fluoride selective electrode, and silver was determined using inductively coupled plasma-mass spectrometry. The mean amount of DSF solution applied to the 3 teeth was 7.57 mg (6.04 μL. Results Over the 4 hour observation period, the mean maximum serum concentrations were 1.86 μmol/L for fluoride and 206 nmol/L for silver. These maximums were reached 3.0 h and 2.5 h for fluoride and silver, respectively. Conclusions Fluoride exposure was below the U.S. Environmental Protection Agency (EPA oral reference dose. Silver exposure exceeded the EPA oral reference dose for cumulative daily exposure over a lifetime, but for occasional use was well below concentrations associated with toxicity. This preliminary study suggests that serum concentrations of fluoride and silver after topical application of DSF should pose little toxicity risk when used in adults. Clinical trials registration NCT01664871.

Polarization tunable photogenerated carrier transfer of CH3NH3PbI3/polyvinylidene fluoride heterostructure

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Yang, Kang; Deng, Zun-Yi; Feng, Hong-Jian

2017-10-01

The integration of ferroelectrics and organic-inorganic halide perovskites could be a promising way to facilitate the separation of electron-hole pairs and charge extraction for the application of solar cells. To explore the effect of the external ferroelectric layer on the CH3NH3PbI3 (MAPbI3) side, we perform first-principles calculations to study the charge transfer properties of the MAPbI3/polyvinylidene fluoride (PVDF) heterostructure. Our calculations demonstrate that the ferroelectric polarization pointing to the PVDF side can clearly facilitate the separation of photo-induced carriers and enhance charge extraction from MAPbI3, while opposite polarization direction hinders the charge extraction and collection. Notably, the carrier behavior at the interface is strongly tuned by the electric field associated with the ferroelectric polarization. In addition, excited state simulation confirms the tunable charge transfer of the MAPbI3/PVDF heterojunction. Therefore, the polarization-driven charge transfer mechanism provides a route for fabricating the ferroelectrics-based high-efficiency photovoltaics and switchable diode devices.

Water Fluoridation: A Critical Review of the Physiological Effects of Ingested Fluoride as a Public Health Intervention

Science.gov (United States)

2014-01-01

Fluorine is the world's 13th most abundant element and constitutes 0.08% of the Earth crust. It has the highest electronegativity of all elements. Fluoride is widely distributed in the environment, occurring in the air, soils, rocks, and water. Although fluoride is used industrially in a fluorine compound, the manufacture of ceramics, pesticides, aerosol propellants, refrigerants, glassware, and Teflon cookware, it is a generally unwanted byproduct of aluminium, fertilizer, and iron ore manufacture. The medicinal use of fluorides for the prevention of dental caries began in January 1945 when community water supplies in Grand Rapids, United States, were fluoridated to a level of 1 ppm as a dental caries prevention measure. However, water fluoridation remains a controversial public health measure. This paper reviews the human health effects of fluoride. The authors conclude that available evidence suggests that fluoride has a potential to cause major adverse human health problems, while having only a modest dental caries prevention effect. As part of efforts to reduce hazardous fluoride ingestion, the practice of artificial water fluoridation should be reconsidered globally, while industrial safety measures need to be tightened in order to reduce unethical discharge of fluoride compounds into the environment. Public health approaches for global dental caries reduction that do not involve systemic ingestion of fluoride are urgently needed. PMID:24719570

Magneto-optical study of holmium iron garnet Ho3Fe5O12

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Kalashnikova, A. M.; Pavlov, V. V.; Kimel, A. V.; Kirilyuk, A.; Rasing, Th.; Pisarev, R. V.

2012-09-01

Bulk holmium iron garnet Ho3Fe5O12 is a cubic ferrimagnet with Curie temperature TC = 567 K and magnetization compensation point in the range 130-140 K. The magneto-optical data are presented for a holmium iron garnet Ho3Fe5O12 film, ˜10 μm thick, epitaxially grown on a (111)-type gadolinium-gallium garnet Gd3Ga5O12 substrate. A specific feature of this structure is that the parameters of the bulk material, from which the film was grown, closely match the substrate ones. The temperature and field dependences of Faraday rotation as well as the temperature dependence of the domain structure in zero field were investigated. The compensation point of the structure was found to be Tcomp = 127 K. It was shown that the temperature dependence of the characteristic size of domain structure diverges at this point. Based on the obtained results we established that the magnetic anisotropy of the material is determined by both uniaxial and cubic contributions, each characterized by different temperature dependence. A complex shape of hysteresis loops and sharp changes of the domain pattern with temperature indicate the presence of collinear-noncollinear phase transitions. Study of the optical second harmonic generation was carried out using 100 fs laser pulses with central photon energy E = 1.55 eV. The electric dipole contribution (both crystallographic and magnetic) to the second harmonic generation was observed with high reliability despite a small mismatch of the film and substrate parameters.

The Impact of Selected Fluoridated Toothpastes on Dental Erosion in Profilometric Measurement.

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Fita, Katarzyna; Kaczmarek, Urszula

2016-01-01

Some fluoridated toothpastes, available commercially, are described to have a protective effect against dental erosion. To evaluate the influence of the selected marketed toothpastes on the human enamel exposed to acid beverages. Enamel specimens from extracted human teeth were prepared (n = 40). Specimens were randomly divided into 10 experimental groups, 4 specimens each, which were subjected to acid challenge for 10 min using orange juice (pH 3.79) or Pepsi Cola (pH 2.58) and then immersed for 2 min into a slurry of five marketed toothpastes with distilled water (1 : 3 w/w). The tested toothpastes contained 1450 or 5000 ppm fluoride, CPP-ACP with 900 ppm fluoride, 1450 ppm fluoride with potassium nitrate 5%, all of them as sodium fluoride, and 700 ppm fluoride as amine and sodium fluoride with 3500 ppm SnCl2. Enamel roughness (Ra parameter) by contact profilometer at baseline and after exposure onto soft drinks and slurry was measured. Exposure to both beverages caused a similar increase of enamel surface roughness. After the specimens immersion into slurries of toothpastes with 1450 or 5000 ppm fluoride, 1450 ppm fluoride with potassium nitrate 5% and CPP-ACP with 900 ppm fluoride the significant decrease of Ra values were found, reaching the baseline values. However, toothpaste with 700 ppm fluoride and 3500 ppm SnCl2 did not cause any fall in Ra value, probably due to other mechanism of action. Within the limitation of the study we can conclude that the sodium fluoride toothpastes are able to restore the surface profile of enamel exposed shortly to acidic soft drinks.

Comparison of the toxicity of fluoridation compounds in the nematode Caenorhabditis elegans.

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Rice, Julie R; Boyd, Windy A; Chandra, Dave; Smith, Marjolein V; Den Besten, Pamela K; Freedman, Jonathan H

2014-01-01

Fluorides are commonly added to drinking water in the United States to decrease the incidence of dental caries. Silicofluorides, such as sodium hexafluorosilicate (Na2 SiF6 ) and fluorosilicic acid (H2 SiF6 ), are mainly used for fluoridation, although fluoride salts such as sodium fluoride (NaF) are also used. Interestingly, only the toxicity of NaF has been examined and not that of the more often used silicofluorides. In the present study, the toxicities of NaF, Na2 SiF6 , and H2 SiF6 were compared. The toxicity of these fluorides on the growth, feeding, and reproduction in the alternative toxicological testing organism Caenorhabditis elegans was examined. Exposure to these compounds produced classic concentration-response toxicity profiles. Although the effects of the fluoride compounds varied among the 3 biological endpoints, no differences were found between the 3 compounds, relative to the fluoride ion concentration, in any of the assays. This suggests that silicofluorides have similar toxicity to NaF. © 2013 SETAC.

Reaction rate constants of HO2 + O3 in the temperature range 233-400 K

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Wang, Xiuyan; Suto, Masako; Lee, L. C.

1988-01-01

The reaction rate constants of HO2 + O3 were measured in the temperature range 233-400 K using a discharge flow system with photofragment emission detection. In the range 233-253 K, the constants are approximately a constant value, and then increase with increasing temperature. This result suggests that the reaction may have two different channels. An expression representing the reaction rate constants is presented.

AN ELISA ASSAY FOR HEME OXYGENASE (HO-1)

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An ELISA assay for heme oxygenase (HO-l ) Abstract A double antibody capture ELISA for the HO-l protein has been developed to separately quantitate HO-I protein. The use of 2.5% NP40 detergent greatly assists in freeing HO-l protein from membranes and/or other cel...