Preparation of antimony-doped nanoparticles by hydrothermal method

Institute of Scientific and Technical Information of China (English)

JIANG Ming-xi; YANG Tian-zu; GU Ying-ying; DU Zuo-juan; LIU Jian-ling

2005-01-01

Antimony-doped tin oxide(ATO) nanoparticles were prepared by the mild hydrothermal method at 200 ℃ using sodium stannate, antimony oxide, sodium hydroxide and sulfuric acid as the starting materials. The doped powders were examined by differential thermal analysis(DTA), X-ray diffractometry(XRD) and transmission electron microscopy(TEM). The doping levels of antimony were determined by volumetric method and iodimetry.The results show that antimony is incorporated into the crystal lattice of tin oxide and the doping levels of antimony in the resulting powders are 2.4%, 4.3 % and 5.1 % (molar fraction). The mean particle size of ATO nanoparticles is in the range of 25 - 30 nm. The effects of antimony doping level on the crystalline size and crystallinity were also discussed.

Sorption of antimony on human teeth

International Nuclear Information System (INIS)

Nofal, M.; Amin, H.; Alian, G.

1997-01-01

The study of the uptake of toxic elements on human teeth represents an interesting research area, as the fate of these elements when present in the human food is of health significance. Since antimony is one of the common toxic elements and since, the chemical behaviour of antimony is similar to that of arsenic, one of the most important toxic elements commonly encountered in cases of food poisoning, it has been decided to investigate its uptake on human teeth and on other restoration materials. The radioactive tracer technique was used to evaluate the concentration of antimony sorbed on teeth. This tracer was obtained by irradiation of antimony metal in the reactor, subsequent dissolution in concentrated sulphuric acid, evaporation to dryness and making the solution 6 M in Hydrochloric acid (1). Antimony prepared in this way is in the trivalent state (Sb III). Sorption was studied in water, tea, coffee, red tea and chicken soup. The highest sorption was achieved from water and chicken soup and least sorption was noticed in case of coffee. The results are presented in the form of the depletion of the radioactivity (A) of antimony with time in presence of a tooth in water and other drinks

Preparation and properties of antimony thin film anode materials

Institute of Scientific and Technical Information of China (English)

SU Shufa; CAO Gaoshao; ZHAO Xinbing

2004-01-01

Metallic antimony thin films were deposited by magnetron sputtering and electrodeposition. Electrochemical properties of the thin film as anode materials for lithium-ion batteries were investigated and compared with those of antimony powder. It was found that both magnetron sputtering and electrodeposition are easily controllable processes to deposit antimony films with fiat charge/discharge potential plateaus. The electrochemical performances of antimony thin films, especially those prepared with magnetron sputtering, are better than those of antimony powder. The reversible capacities of the magnetron sputtered antimony thin film are above 400 mA h g-1 in the first 15 cycles.

Solubility behaviour of antimony(III) and antimony(V) solids in basic aqueous solutions at 300{sup o}C

Energy Technology Data Exchange (ETDEWEB)

Lemire, R.J.; Tosello, N.B.; Halliday, J.D

1999-12-01

The major contributions of the isotopes {sup 122}Sb and {sup 124}Sb to activity transport in a CANDU reactor primary heat transport system (HTS), have been associated with oxygen ingress during reactor shutdown. As part of a program to minimize the release and redeposition of these isotopes, the solubilities of antimony(III) and (V) oxides and salts have been measured in basic solutions at temperatures from 25 to 300{sup o}C. The results provide information on the charge and the stability as a function of temperature of antimony solution species and, hence, a guide to the trends in the temperature dependence of the solubilities of antimony solids. In solutions in which oxidation of antimony(III) to antimony(V) is minimized, the solubility of Sb{sub 2}O{sub 3} increases by about two orders of magnitude between 25 and 200{sup o}C, and then levels out or decreases slightly. At 250{sup o}C, in oxidizing solutions, Sb{sub 2}O{sub 5}{center_dot}xH{sub 2}O and simple sodium antimonate(V) were found to be unstable in sodium hydroxide solutions with respect to the solid, Na{sub 2{alpha}}[H(H{sub 2}O)]{sub 2-2{alpha}}Sb{sub 2}O{sub 6}, which has a pyrochlore structure. The solubility of this partially protonated sodium antimonate increases from 25 to 200{sup o}C and decreases at temperatures above 250{sup o}C. These solubility changes for the antimony (V) solids reflect changes in the stability of the anionic antimony solution species (SbO{sub 3}{sup -} or Sb(OH){sub 6}{sup -}), even though the compositions of antimony-containing solids in basic oxidizing solutions are strongly dependent on the cations and their aqueous phase concentrations. All solids used in the present experiments would be expected to generate total solution antimony concentrations {>=} 0.00005 mol{center_dot}dm{sup -3} in any neutral or basic aqueous solutions (assuming no added sodium salts). Therefore, under HTS conditions, precipitation of any antimony oxides or mixed oxides is unlikely. It cannot be

Perspectives of antimony compounds in oncology

Institute of Scientific and Technical Information of China (English)

Pankaj SHARMA; Diego PEREZ; Armando CABRERA; Nee ROSAS; Jose Luis ARIAS

2008-01-01

Antimony, a natural element that has been used as a drug for over more than 100 years, has remarkable therapeutic efficacy in patients with acute promyelocytic leukemia. This review focuses on recent advances in developing antimony anti- cancer agents with an emphasis on antimony coordination complexes, Sb (Ⅲ) and Sb (V). These complexes, which include many organometallic complexes, may provide a broader spectrum of antitumoral activity. They were compared with classical platinum anticancer drugs. The review covers the literature data pub- lished up to 2007. A number of antimonials with different antitumoral activities are known and have diverse applications, even though little research has been done on their possibilities. It might be feasible to develop more specific and effective inhibitors for phosphatase-targeted, anticancer therapeutics through the screen- ing of sodium stibogluconate (SSG) and potassium antimonyltartrate-related compounds, which are comprised of antimony conjugated to different organic moieties. For example, SSG appears to be a better inhibitor than suramin which is a compound known for its antineoplastic activity against several types of cancers.

Antimony: a flame fighter

Science.gov (United States)

Wintzer, Niki E.; Guberman, David E.

2015-01-01

Antimony is a brittle, silvery-white semimetal that conducts heat poorly. The chemical compound antimony trioxide (Sb2O3) is widely used in plastics, rubbers, paints, and textiles, including industrial safety suits and some children’s clothing, to make them resistant to the spread of flames. Also, sodium antimonate (NaSbO3) is used during manufacturing of high-quality glass, which is found in cellular phones.

Pharmacokinetic of antimony in mice with cutaneous Leishmaniasis

Energy Technology Data Exchange (ETDEWEB)

Borborema, Samanta E.T.; Nascimento, Nanci do [Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN-SP, Sao Paulo, SP (Brazil). Lab. de Biologia Molecular]. E-mails: samanta@usp.br; nnascime@ipen.br; Andrade Junior, Heitor F. de [Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN-SP, Sao Paulo, SP (Brazil). Lab. de Biologia Molecular; Instituto de Medicina Tropical de Sao Paulo, Sao Paulo, SP (Brazil); E-mail: hfandrad@usp.br; Osso Junior, Joao A. [Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN-SP, Sao Paulo, SP (Brazil). Centro de Radiofarmacia]. E-mail: jaosso@ipen.br

2007-07-01

Cutaneous Leishmaniasis (CL) remains a major world health problem, with about 1.5 million new cases each year. Caused by protozoa Leishmania, in South America, this infection can vary from a chronic skin ulcer, to an erosive mucosal disease and severe facial disfigurement. Pentavalent antimony (Sb{sup +5}) as sodium stibogluconate (Pentostam) or meglumine antimoniate (Glucantime) are main drugs for treating most forms of human leishmaniasis. For six decades, despite the recent developments, the effective therapy to cutaneous leishmaniasis has been based on long parenteral courses of such drugs, even though these are fairly costly, toxic and inconvenient to use, without adequate knowledge on their pharmacokinetics or mechanism of action. Pharmacokinetics studies could be based on bioactive traceable drugs, usually with radioactive isotopes, but antimony radioisotopes are unavailable commercially. Neutron irradiation is a powerful tool in the analysis of mineral content of samples, for antimony, there are at least two main isotopes that could be formed after neutron irradiation in nuclear reactor. The aim of the present study was to construct antimony salts with those radioisotopes to obtain tracers to compare the pharmacokinetic and the tissue distribution of neutron irradiated meglumine antimoniate in healthy and cutaneous leishmaniasis experimentally infected mice. Meglumine antimoniate, (Glucantime, Aventis, S.P, Brazil), was neutron irradiated inside the IEA-R1 nuclear reactor (IPEN/CNEN-SP), producing two radioisotopes {sup 122}Sb and {sup 124}Sb. Its biodistribution was verified in BALB/c mice experimentally infected with Leishmania (Leishmania) Amazonensis, which received a single intraperitoneal dose of the drug. At different times after injection, the tissues and blood were excised and activity measured in a NaI (Tl) scintillation counter. Compared with the healthy mice, experimentally infected mice had significantly lower maximum concentration of antimony

Pharmacokinetic of antimony in mice with cutaneous Leishmaniasis

International Nuclear Information System (INIS)

Borborema, Samanta E.T.; Nascimento, Nanci do; Osso Junior, Joao A.

2007-01-01

Cutaneous Leishmaniasis (CL) remains a major world health problem, with about 1.5 million new cases each year. Caused by protozoa Leishmania, in South America, this infection can vary from a chronic skin ulcer, to an erosive mucosal disease and severe facial disfigurement. Pentavalent antimony (Sb +5 ) as sodium stibogluconate (Pentostam) or meglumine antimoniate (Glucantime) are main drugs for treating most forms of human leishmaniasis. For six decades, despite the recent developments, the effective therapy to cutaneous leishmaniasis has been based on long parenteral courses of such drugs, even though these are fairly costly, toxic and inconvenient to use, without adequate knowledge on their pharmacokinetics or mechanism of action. Pharmacokinetics studies could be based on bioactive traceable drugs, usually with radioactive isotopes, but antimony radioisotopes are unavailable commercially. Neutron irradiation is a powerful tool in the analysis of mineral content of samples, for antimony, there are at least two main isotopes that could be formed after neutron irradiation in nuclear reactor. The aim of the present study was to construct antimony salts with those radioisotopes to obtain tracers to compare the pharmacokinetic and the tissue distribution of neutron irradiated meglumine antimoniate in healthy and cutaneous leishmaniasis experimentally infected mice. Meglumine antimoniate, (Glucantime, Aventis, S.P, Brazil), was neutron irradiated inside the IEA-R1 nuclear reactor (IPEN/CNEN-SP), producing two radioisotopes 122 Sb and 124 Sb. Its biodistribution was verified in BALB/c mice experimentally infected with Leishmania (Leishmania) Amazonensis, which received a single intraperitoneal dose of the drug. At different times after injection, the tissues and blood were excised and activity measured in a NaI (Tl) scintillation counter. Compared with the healthy mice, experimentally infected mice had significantly lower maximum concentration of antimony and high

Microbial antimony biogeochemistry: Enzymes, regulation, and related metabolic pathways

Science.gov (United States)

Li, Jingxin; Qian Wang,; Oremland, Ronald S.; Kulp, Thomas R.; Rensing, Christopher; Wang, Gejiao

2016-01-01

Antimony (Sb) is a toxic metalloid that occurs widely at trace concentrations in soil, aquatic systems, and the atmosphere. Nowadays, with the development of its new industrial applications and the corresponding expansion of antimony mining activities, the phenomenon of antimony pollution has become an increasingly serious concern. In recent years, research interest in Sb has been growing and reflects a fundamental scientific concern regarding Sb in the environment. In this review, we summarize the recent research on bacterial antimony transformations, especially those regarding antimony uptake, efflux, antimonite oxidation, and antimonate reduction. We conclude that our current understanding of antimony biochemistry and biogeochemistry is roughly equivalent to where that of arsenic was some 20 years ago. This portends the possibility of future discoveries with regard to the ability of microorganisms to conserve energy for their growth from antimony redox reactions and the isolation of new species of “antimonotrophs.”

Inhibition of DNA-double strand break repair by antimony compounds

International Nuclear Information System (INIS)

Takahashi, Sentaro; Sato, Hiroshi; Kubota, Yoshihisa; Utsumi, Hiroshi; Bedford, Joel S.; Okayasu, Ryuichi

2002-01-01

DNA double strand breaks (DSBs), induced by γ-irradiation in Chinese hamster ovary cells, were used to examine whether antimony compounds affect the repair of DNA damage. The cells were first incubated with antimony trichloride or antimony potassium tartrate (both Sb(III)) for 2 h, and then irradiated with γ-rays at a dose of 40 Gy. The DNA DSB was quantified with pulsed field gel electrophoresis immediately after irradiation (non-repair group) as well as at 30 min post-irradiation (repair group). The degree of repair inhibition was determined by the differences in the amount of DNA DSB between non-repair and repair groups. Both antimony compounds inhibited repair of DNA DSB in a dose dependent manner. In trichloride, 0.2 mM antimony significantly inhibited the rejoining of DSB, while 0.4 mM was necessary in potassium antimony tartrate. The mean lethal doses, D 0 , for the treatment with antimony trichloride and antimony potassium tartrate, were approximately 0.21 and 0.12 mM, respectively. This indicates that the repair inhibition by antimony trichloride occurred in the dose range near D 0 , but the antimony potassium tartrate inhibited the repair at doses where most cells lost their proliferating ability. This is the first report to indicate that antimony compounds may inhibit the repair of radiation-induced DNA DSB

Research on the Characteristics and Mechanism of the Cumulative Release of Antimony from an Antimony Smelting Slag Stacking Area under Rainfall Leaching

Science.gov (United States)

Zhou, Yingying; Deng, Renjian

2017-01-01

We aimed to study the characteristics and the mechanism of the cumulative release of antimony at an antimony smelting slag stacking area in southern China. A series of dynamic and static leaching experiments to simulate the effects of rainfall were carried out. The results showed that the release of antimony from smelting slag increased with a decrease in the solid-liquid ratio, and the maximum accumulated release was found to be 42.13 mg Sb/kg waste and 34.26 mg Sb/kg waste with a solid/liquid ratio of 1 : 20; the maximum amount of antimony was released within 149–420 μm size fraction with 7.09 mg/L of the cumulative leaching. Also, the antimony release was the greatest and most rapid at pH 7.0 with the minimum release found at pH 4.0. With an increase in rainfall duration, the antimony release increased. The influence of variation in rainfall intensity on the release of antimony from smelting slag was small. PMID:28804669

FIRST REPORT ON OTOTOXICITY OF MEGLUMINE ANTIMONIATE

Directory of Open Access Journals (Sweden)

Cláudia Maria Valete-Rosalino

2014-09-01

Full Text Available Introduction: Pentavalent antimonials are the first drug of choice in the treatment of tegumentary leishmaniasis. Data on ototoxicity related with such drugs is scarcely available in literature, leading us to develop a study on cochleovestibular functions. Case Report: A case of a tegumentary leishmaniasis patient, a 78-year-old man who presented a substantial increase in auditory threshold with tinnitus and severe rotatory dizziness during the treatment with meglumine antimoniate, is reported. These symptoms worsened in two weeks after treatment was interrupted. Conclusion: Dizziness and tinnitus had already been related to meglumine antimoniate. However, this is the first well documented case of cochlear-vestibular toxicity related to meglumine antimoniate.

How can we adapt to geological scarcity of antimony? Investigation of antimony's substitutability and of other measures to achieve a sustainable use

NARCIS (Netherlands)

Henckens, M.L.C.M.; Driessen, P.P.J.; Worrell, E.

Abstract Antimony is an element that is applied in many useful applications for mankind. However, antimony resources are very scarce, when comparing the current extraction rates with the availability of antimony containing ores. From an inter-temporal sustainability perspective, current generations

The exposure to and health effects of antimony

DEFF Research Database (Denmark)

Cooper, Ross G.; Harrison, Adrian Paul

2009-01-01

. Antimony toxicity is dependent on the exposure dose, duration, route (breathing, eating, drinking, or skin contact), other chemical exposures, age, sex, nutritional status, family traits, life style, and state of health. Chronic exposure to antimony in the air at levels of 9 mg/m3 may exacerbate irritation...... of the eyes, skin, and lungs. Long-term inhalation of antimony can potentiate pneumoconiosis, altered electrocardiograms, stomach pain, diarrhea, vomiting, and stomach ulcers, results which were confirmed in laboratory animals. Although there were investigations of the effect of antimony in sudden infant...

Effect of antimony on lead-acid battery negative

International Nuclear Information System (INIS)

Mahato, B.K.; Bullock, K.R.; Strebe, J.L.; Wilkinson, D.F.

1985-01-01

The role of antimony on the lead-acid battery negative in terms of its effect on charge efficiency, its effect on gassing overpotential, its interactive influence with lignin expander in controlling the charge efficiency, and its retentive behavior or purging characteristics as SbH 3 in the overcharge gas stream was investigated. Linear potential sweep (LPS) cycling of Plante-type lead electrodes were used to determine the effect of antimony on gassing overpotential and to monitor its concentration either in the active material or the exit gas stream. Results showed a significant contribution of antimony in decreasing charge efficiency and an overwhelming role of lignin expander in suppressing the effect of antimony on charge efficiency. The critical lead-electrode potential for purging antimony from the electrode is close to -1275 mV (vs. Hg/Hg 2 SO 4 )

[Pollution characteristics of antimony, arsenic and mercury in human hair at Xikuangshan antimony mining area and Guiyang City, China].

Science.gov (United States)

Liu, Bi-Jun; Wu, Feng-Chang; Deng, Qiu-Jing; Mo, Chang-Li; Zhu, Jing; Zeng, Li; Fu, Zhi-You; Li, Wen

2009-03-15

The concentration levels of antimony, arsenic and mercury in human hair collected from Xikuangshan antimony mining area and Guiyang City were determined by hydride generation-atomic fluorescence spectrometry after having been digested by nitric acid and perchloric acid. The contents of Sb, As and Hg are 15.9, 4.21, 1.79 microg/g in the samples from Xikuangshan antimony mining area and 0.532, 0.280, 0.338 microg/g in the samples from Guiyang City respectively. The contents of Sb, As and Hg in human hair of Xikuangshan antimony area are much higher than those of Guiyang City. The independent-samples t-test shows that there are no marked differences in the contents of Sb and As between male and female hair samples from both Xikuangshan antimony mining area and Guiyang City (p > 0.05), while Hg contents in male hair are apparently higher than those in female hair from Guiyang City (p mining area may significantly affect human health than in the un-mining areas.

Effect of precipitation route on the properties of antimony trioxide

International Nuclear Information System (INIS)

Abdullah, Abdul Halim; Noor, Nor Hayati Mohd; Ramli, Irmawati; Hashim, Mansor

2008-01-01

Antimony trioxide was prepared, using antimony potassium tartarate as starting material, via forward and reverse precipitation technique. The characteristics of the resulting antimony oxides were determined by BET surface area method, differential thermogravimetry analysis (DTG), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and SEM. The DTG curves for all uncalcined samples showed only a single endothermic peak which indicated that the sample is antimony trioxide. Unlike forward precipitation technique which resulted in a single antimony trioxide phase which is senarmontite, reverse precipitation technique produced antimony trioxide with both senarmontite and valentinite phase. Upon calcinations at 723 K, a small amount of Sb 2 O 4 with cervantite phase was formed at the expense of Sb 2 O 3 senarmontite phase as detected from the XRD pattern and infrared spectrum of RSb. The effect of preparation route on the properties of the antimony trioxide produced was clearly demonstrated

Antimony and sleep-related disorders: NHANES 2005-2008.

Science.gov (United States)

Scinicariello, Franco; Buser, Melanie C; Feroe, Aliya G; Attanasio, Roberta

2017-07-01

Antimony is used as a flame-retardant in textiles and plastics, in semiconductors, pewter, and as pigments in paints, lacquers, glass and pottery. Subacute or chronic antimony poisoning has been reported to cause sleeplessness. The prevalence of short sleep duration (sleep apnea (OSA) affects 12-28 million US adults. Insufficient sleep and OSA have been linked to the development of several chronic conditions including diabetes, cardiovascular disease, obesity and depression, conditions that pose serious public health threats. To investigate whether there is an association between antimony exposure and sleep-related disorders in the US adult population using the National Health and Nutrition Examination Survey (NHANES) 2005-2008. We performed multivariate logistic regression to analyze the association of urinary antimony with several sleep disorders, including insufficient sleep and OSA, in adult (ages 20 years and older) participants of NHANES 2005-2008 (n=2654). We found that participants with higher urinary antimony levels had higher odds to experience insufficient sleep (≤6h/night) (OR 1.73; 95%CI; 1.04, 2.91) as well as higher odds to have increased sleep onset latency (>30min/night). Furthermore, we found that higher urinary antimony levels in participants were associated with OSA (OR 1.57; 95%CI; 1.05, 2.34), sleep problems, and day-time sleepiness. In this study, we found that urinary antimony was associated with higher odds to have insufficient sleep and OSA. Because of the public health implications of sleep disorders, further studies, especially a prospective cohort study, are warranted to evaluate the association between antimony exposure and sleep-related disorders. Copyright © 2017. Published by Elsevier Inc.

Antimony removal from aqueous solutions using Zirconium hydroxide

International Nuclear Information System (INIS)

Petrescu, D.; Velciu, L.; Bucur, C.

2016-01-01

In this paper it is presented an experimental test for non-radioactive antimony removal from aqueous solutions using zirconium hydroxide powder. Also, it was studied how the temperature and pH influences antimony adsorption onto zirconium hydroxide surface. After the adsorption, solutions were filtered on Cellulose Mixed Ester Membrane with 0.2 μm pore size to remove the zirconium powder and then the aqueous solutions were sent to Inductively Coupled Plasma Optic Emission Spectrometry (ICP-OES) for quantitative analysis of Sb. Zirconium hydroxide powders were examined by optical microscopy. For the solutions that were tested at pH 4.5 and 10.2 the antimony concentration dropped below the detection limit of ICP-OES device, proof of antimony adsorption on zirconium hydroxide. Also, for the other tested solutions which had pH=12 the antimony concentration reduced with 77% and 80%. The temperature had no influence upon adsorption mechanism. (authors)

In vitro antileishmanial properties of neutron-irradiated meglumine antimoniate

Energy Technology Data Exchange (ETDEWEB)

Borborema, Samanta Etel Treiger; Nascimento, Nanci do [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), SP (Brazil). Lab. de Biologia Molecular]. E-mail: samanta@usp.br; Osso Junior, Joao Alberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), SP (Brazil). Centro de Radiofarmacia]. E-mail: jaosso@ipen.br; Andrade Junior, Heitor Franco de [Instituto de Medicina Tropical de Sao Paulo (IMT-SP), SP (Brazil). Lab. de Protozoologia]. E-mail:hfandrad@usp.br

2005-10-15

Pentavalent antimony, as meglumine antimoniate (Glucantime) or sodium stibogluconate (Pentostam), is the main treatment for leishmaniasis, a complex of diseases caused by the protozoan Leishmania, and an endemic and neglected threat in Brazil. Despite over half a century of clinical use, their mechanism of action, toxicity and pharmacokinetic data remain unknown. The analytical methods for determination of antimony in biological systems remain complex and have low sensitivity. Radiotracer studies have a potential in pharmaceutical development. The aim of this study was to obtain a radiotracer for antimony, with suitable physical and biological properties. Meglumine antimoniate was neutron irradiated inside the IEA-R1 nuclear reactor, producing two radioisotopes {sup 122} Sb and {sup 124} Sb, with high radionuclidic purity and good specific activity. This compound showed the same antileishmanial activity as the native compound. The use of the radiotracers, easily created by neutron irradiation, could be an interesting tool to solve important questions in antimonial pharmacology. (author)

Mineral resource of the month: antimony

Science.gov (United States)

,

2008-01-01

The article describes the characteristics and industrial uses of antimony. Antimony, which is produced as a byproduct of mining other metals such as gold, lead or silver, is used in everything from flame retardants, batteries, ceramics and glass. It is also used in glass for television picture tubes, computer monitors, pigments and catalysts.

ANTIMONY INDUCED CRYSTALLIZATION OF AMORPHOUS SILICON

Institute of Scientific and Technical Information of China (English)

Y. Wang; H.Z. Li; C.N. Yu; G.M. Wu; I. Gordon; P. Schattschneider; O. Van Der Biest

2007-01-01

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE(molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.

Arsenic and Antimony Transporters in Eukaryotes

Directory of Open Access Journals (Sweden)

Ewa Maciaszczyk-Dziubinska

2012-03-01

Full Text Available Arsenic and antimony are toxic metalloids, naturally present in the environment and all organisms have developed pathways for their detoxification. The most effective metalloid tolerance systems in eukaryotes include downregulation of metalloid uptake, efflux out of the cell, and complexation with phytochelatin or glutathione followed by sequestration into the vacuole. Understanding of arsenic and antimony transport system is of high importance due to the increasing usage of arsenic-based drugs in the treatment of certain types of cancer and diseases caused by protozoan parasites as well as for the development of bio- and phytoremediation strategies for metalloid polluted areas. However, in contrast to prokaryotes, the knowledge about specific transporters of arsenic and antimony and the mechanisms of metalloid transport in eukaryotes has been very limited for a long time. Here, we review the recent advances in understanding of arsenic and antimony transport pathways in eukaryotes, including a dual role of aquaglyceroporins in uptake and efflux of metalloids, elucidation of arsenic transport mechanism by the yeast Acr3 transporter and its role in arsenic hyperaccumulation in ferns, identification of vacuolar transporters of arsenic-phytochelatin complexes in plants and forms of arsenic substrates recognized by mammalian ABC transporters.

Arsenic and Antimony Transporters in Eukaryotes

Science.gov (United States)

Maciaszczyk-Dziubinska, Ewa; Wawrzycka, Donata; Wysocki, Robert

2012-01-01

Arsenic and antimony are toxic metalloids, naturally present in the environment and all organisms have developed pathways for their detoxification. The most effective metalloid tolerance systems in eukaryotes include downregulation of metalloid uptake, efflux out of the cell, and complexation with phytochelatin or glutathione followed by sequestration into the vacuole. Understanding of arsenic and antimony transport system is of high importance due to the increasing usage of arsenic-based drugs in the treatment of certain types of cancer and diseases caused by protozoan parasites as well as for the development of bio- and phytoremediation strategies for metalloid polluted areas. However, in contrast to prokaryotes, the knowledge about specific transporters of arsenic and antimony and the mechanisms of metalloid transport in eukaryotes has been very limited for a long time. Here, we review the recent advances in understanding of arsenic and antimony transport pathways in eukaryotes, including a dual role of aquaglyceroporins in uptake and efflux of metalloids, elucidation of arsenic transport mechanism by the yeast Acr3 transporter and its role in arsenic hyperaccumulation in ferns, identification of vacuolar transporters of arsenic-phytochelatin complexes in plants and forms of arsenic substrates recognized by mammalian ABC transporters. PMID:22489166

Determining arsenic in elemental antimony containing selenium and tellurium

International Nuclear Information System (INIS)

Mogileva, M.G.; Kozlova, E.L.

1986-01-01

The authors have developed a method of determining arsenic in metallic antimony containing selenium, tellurium, and mercury, in which they isolated it in elementary form for separation from the antimony and the associated elements (silicon and phosphorus), followed by colorimetric determination of the arsenic from arsenic-molbdenum blue. The reducing agents to reduce the arsenic were sodium hypophosphite and tin(II) chloride, which do not reduce antimony and which do not interfere with the determination. This method of determining arsenic in metallic antimony without preliminary separation of the selenium and tellurium is in no way inferior in accuracy to the method given in All-Union State Standard (GOST) 1367.4-83

Electrical properties of cadmium telluride films doped with antimony

International Nuclear Information System (INIS)

Atdaev, B.S.; Garyagdyev, G.; Grin', V.F.; Noskov, A.I.

1989-01-01

Effect of cadmium telluride doping with antimony on electric and photoelectric properties is investigated. Temperature dependence of dark (σ d ) and photoconductivity (σ p ) during excitation from the range of proper absorption in the temperature range 77-300 K and spectral distribution of photoconductivity at 300 K are investigated. It is shown that in the process of doping antimony diffusses intensively over CdTe grain boundaries, decreasing potential barriers between them and due to diffusion into CdTe grains it changes their electrical properties. The acceptor character of antimony impurity can be caused by antimony diffusion into tellurium sublattice owing to proximity of their ionic and covalent radii

40 CFR 721.5547 - Antimony double oxide.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Antimony double oxide. 721.5547 Section 721.5547 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.5547 Antimony double oxide. (a)...

Antimony measurement in high pressure reactor water loop

International Nuclear Information System (INIS)

Svarc, V.; Dudjakova, K.; Martykan, M.; Sus, F.; Kysela, J.

2005-01-01

RVS 3 loop is highly contaminated due to antimony main circulating pump bearings. Antimony is one of the major contaminant in PWR units. Different technologies to remove Sb from the systems have been tried. (N.T.)

Potential of rice husks for antimony removal

International Nuclear Information System (INIS)

Khalid, Nasir; Ahmad, Shujaat; Toheed, Aqidat; Ahmed, Jamil

2000-01-01

The adsorption behavior of rice husks for antimony ions from aqueous solutions has been investigated as a function of appropriate electrolyte, equilibration time, hydrogen ions, amount of adsorbent, concentration of adsorbate, effect of diverse ions and temperature. The best conditions in which this material can be used as adsorbent have been explored. The radiotracer technique was employed to determine the distribution of antimony ( 122 Sb) using a batch method. Maximum adsorption was observed at 0.01 mol L -1 acid solutions (HNO 3 , HCl, H 2 SO 4 and HClO 4 ) using 1.0 g of adsorbent for 1.92x10 -5 mol L -1 antimony concentration in 10 min equilibration time. Studies show that the adsorption decreases with the increase in the concentrations of all the acids. The adsorption data follow the Freundlich isotherm over the range of 1.92x10 -5 to 2.05x10 -4 mol L -1 antimony concentration. The characteristic Freundlich constants i.e., 1/n=0.82±0.05 and K=4.61±0.07 m mol g -1 have been computed for the sorption system. The uptake of antimony increases with the rise in temperature (299-323 K). Thermodynamic quantities i.e., ΔG 0 , ΔS 0 and ΔH 0 have also been calculated for the system. The sorption process was found to be endothermic

Thermodynamic Behavior of Lead-Antimony Alloy in Vacuum Distillation

Institute of Scientific and Technical Information of China (English)

1989-01-01

The distribution of metals in Pb-Sb ailoy during vacuum distillation was calculated.The composition curve of vapor-liquid phases determined by this work is different from those of. other researchers.The curve intersects the diagonal at C.The compositions of vapor and liquid at C are identical.The antimony content of vapor on the left of C is less than that of liquid,and the vapor on the right-side of C contains more antimony.These characteristics can be applied to the elimination of antimony from crude lead or the elimination of lead from crude antimony.The position of C moves rightwards with temperature increment.The discrepency among the compositions of C suggested by diffrent authors was explained.

The potential DNA toxic changes among workers exposed to antimony trioxide.

Science.gov (United States)

El Shanawany, Safaa; Foda, Nermine; Hashad, Doaa I; Salama, Naglaa; Sobh, Zahraa

2017-05-01

Occupational exposure to antimony has gained much interest when specific toxic effects were noticed among workers processing antimony. Thus, the aim of the present work was to investigate the potential DNA oxidative damage occurring among Egyptian workers occupationally exposed to antimony trioxide. The study was conducted on 25 subjects exposed to antimony trioxide while working in the polymerization process of polyester in Misrayon and Polyester Fiber Company, KafrEldawwar, Beheira, Egypt. Urinary antimony levels were assessed using inductive coupled plasma-optical emission spectrometry (ICP-OES) and considered as a biological exposure index. DNA damage and total oxidant capacity (TOC) were assessed using ELISA. DNA damage was detected in the form of increased apurinic/apyrimidinic (AP) sites among antimony trioxide-exposed workers compared to control subjects, but it could not be explained by oxidative mechanisms due to lack of significant correlation between DNA damage and measured TOC. Antimony trioxide might have a genotoxic impact on occupationally exposed workers which could not be attributed to oxidative stress in the studied cases.

21 CFR 862.3110 - Antimony test system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Antimony test system. 862.3110 Section 862.3110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Toxicology Test Systems § 862.3110 Antimony test system. (a) Identification. A...

Blocking of indium incorporation by antimony in III-V-Sb nanostructures

International Nuclear Information System (INIS)

Sanchez, A M; Beltran, A M; Ben, T; Molina, S I; Beanland, R; Gass, M H; De la Pena, F; Walls, M; Taboada, A G; Ripalda, J M

2010-01-01

The addition of antimony to III-V nanostructures is expected to give greater freedom in bandgap engineering for device applications. One of the main challenges to overcome is the effect of indium and antimony surface segregation. Using several very high resolution analysis techniques we clearly demonstrate blocking of indium incorporation by antimony. Furthermore, indium incorporation resumes when the antimony concentration drops below a critical level. This leads to major differences between nominal and actual structures.

Studies on the dissolution of antimony doped ferrites

International Nuclear Information System (INIS)

Keny, S.J.; Kumbhar, A.G.; Sanjukta, A.; Pandey, S.; Venkateswaran, G.; Ramanathan, S.

2008-01-01

Antimony (Sb) present in the PHT (primary heat transport) pump seals and bearings of PHWRs (Pressurized Heavy Water Reactor) is released during operation of the reactor and gets deposited on the in-core zircaloy surfaces. Neutron flux in the reactor core activates this Sb to 122 Sb (t 1/2 2.6 days) and 124 Sb (t 1/2 60 days). Release of this Sb (radioactive antimony) and its deposition on out of core surfaces occurs due to oxygen ingress in the system during shutdown periods and off normal conditions. Sb deposition on the magnetite bearing carbon steel surface of the PHT system results in increase of radiation fields. The consequence of this is low apparent decontamination factors observed after system decontamination. Once Sb is deposited on bare carbon steel (CS) surface or magnetite bearing carbon steel surface it is not amenable for removal by normal reductive decontamination process. It has to decay by its own half-life or has to be removed by oxidative dissolution. To understand the role of antimony and its removal on the ion exchange column, antimony doped ferrites were prepared and their dissolution in CNA (citric acid, NTA, Ascorbic acid; 1.4+1.4+1.7 mM) formulation was studied. The time taken for the dissolution of antimony-doped ferrites was found to increase with increasing Sb content in the ferrite. The point of zero charge (pzc) value of Sb substituted magnetite was determined to understand its adsorption on carbon steel surfaces of the PHT system. The pzc values for Fe 3 O 4 and Sb 2 O 3 , with H + / OH - as only potential determining ions in the aqueous medium, were 6.5 and 1.7 respectively. While, pzc of magnetite in typical decontamination formulations was below 3. The pzc for aqueous suspension of antimony-substituted magnetite (sintered at 1173 K) was 4.4. On the other hand, in CEA (citric acid, EDTA, Ascorbic acid) formulation up to a pH of 1.5, surface charge on the antimony-substituted magnetite was negative. Hence, even at this low pH, pzc

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

Antimony distribution and environmental mobility at an historic antimony smelter site, New Zealand

International Nuclear Information System (INIS)

Wilson, N.J.; Craw, D.; Hunter, K.

2004-01-01

A historic antimony smelter site at Endeavour Inlet, New Zealand has smelter residues with up to 17 wt.% antimony. Residues include coarse tailings (cm scale particles, poorly sorted), sand tailings (well sorted) and smelter slag (blocks up to 30 cm across). All of this material has oxidised to some degree over the ca. 100 years since the site was abandoned. Oxidation has resulted in acidification of the residues down to pH 2-5. Smelter slag contains pyrrhotite (FeS) and metallic antimony, and oxidation is restricted to surfaces only. The coarse tailings are the most oxidised, and few sulfide grains persist. Unoxidised sand tailings contain 10-20 vol.% stibnite (Sb 2 S 3 ) containing up to 5% As, with subordinate arsenopyrite (FeAsS), and minor pyrite (FeS 2 ). The sand tailings are variably oxidised on a scale of 2-10 cm, but original depositional layering is preserved during oxidation and formation of senarmontite (Sb 2 O 3 ). Oxidation of sand tailings has resulted in localised mobility of both Sb and As on the cm scale, resulting in redistribution of these metalloids with iron oxyhydroxide around sand grain boundaries. Experiments demonstrate that Sb mobility decreases with time on a scale of days. Attenuation of both As and Sb occurs due to adsorption on to iron oxyhydroxides which are formed during oxidation of the smelter residues. There is no detectable loss of Sb or As from the smelter site into the adjacent river, <50 m away, which has elevated Sb (ca. 20 μg/l) and As (ca. 7 μg /l) from mineralised rocks upstream. Despite the high concentrations of Sb and As in the smelter residues, these metalloids are not being released into the environment. - High levels of antimony in primitive smelter soils remain largely immobile on the metre scale

Antimony leaching from polyethylene terephthalate (PET) plastic used for bottled drinking water.

Science.gov (United States)

Westerhoff, Paul; Prapaipong, Panjai; Shock, Everett; Hillaireau, Alice

2008-02-01

Antimony is a regulated contaminant that poses both acute and chronic health effects in drinking water. Previous reports suggest that polyethylene terephthalate (PET) plastics used for water bottles in Europe and Canada leach antimony, but no studies on bottled water in the United States have previously been conducted. Nine commercially available bottled waters in the southwestern US (Arizona) were purchased and tested for antimony concentrations as well as for potential antimony release by the plastics that compose the bottles. The southwestern US was chosen for the study because of its high consumption of bottled water and elevated temperatures, which could increase antimony leaching from PET plastics. Antimony concentrations in the bottled waters ranged from 0.095 to 0.521 ppb, well below the US Environmental Protection Agency (USEPA) maximum contaminant level (MCL) of 6 ppb. The average concentration was 0.195+/-0.116 ppb at the beginning of the study and 0.226+/-0.160 ppb 3 months later, with no statistical differences; samples were stored at 22 degrees C. However, storage at higher temperatures had a significant effect on the time-dependent release of antimony. The rate of antimony (Sb) release could be fit by a power function model (Sb(t)=Sb 0 x[Time, h]k; k=8.7 x 10(-6)x[Temperature ( degrees C)](2.55); Sb 0 is the initial antimony concentration). For exposure temperatures of 60, 65, 70, 75, 80, and 85 degrees C, the exposure durations necessary to exceed the 6 ppb MCL are 176, 38, 12, 4.7, 2.3, and 1.3 days, respectively. Summertime temperatures inside of cars, garages, and enclosed storage areas can exceed 65 degrees C in Arizona, and thus could promote antimony leaching from PET bottled waters. Microwave digestion revealed that the PET plastic used by one brand contained 213+/-35 mgSb/kg plastic; leaching of all the antimony from this plastic into 0.5L of water in a bottle could result in an antimony concentration of 376 ppb. Clearly, only a small

Effect of temperature during ion sputtering on the surface segregation rate of antimony in an iron-antimony alloy at higher temperatures

International Nuclear Information System (INIS)

Oku, M.; Hirokawa, K.; Kimura, H.; Suzuki, S.

1986-01-01

The surface segregation of antimony in an iron-0.23 at% antimony alloy was studied by XPS. The segregation rate in the temperature range between 800 and 900 K depends on the temperature during sputtering with argon ion of kinetic energy of 1 keV. The sputtering at room temperature or 473 K gives higher values of the segregation rate than those at 673 K. Both cases give the activation energy of 170 kJmol -1 for the surface segregation rate. The segregation of antimony is not observed after the sample is heated at 1000 K. (author)

The investigation of antimony extraction with tributyl phosphate from nitric acid solutions

International Nuclear Information System (INIS)

Lakaev, V.S.; Smelov, V.S.

1988-01-01

Experimental data on trivalent antimony extraction with tributyl phosphate from nitric acid solutions containing (3.2-4.3)x10 -6 mol/l of antimony-125 isotope are presented. Possible mechanism of antimony (3) extraction is determined and the concentration constant for this process is calculated. Effect of temperature on the extraction of trivalent antimony is estimated. The values of enthalpy, free enthalpy and entropy are determined

Electron irradiation effects in amorphous antimony thin films obtained by cluster-beam deposition

Energy Technology Data Exchange (ETDEWEB)

Fuchs, G.; Treilleux, M.; Santos Aires, F.; Cabaud, B.; Melinon, P.; Hoareau, A. (Lyon-1 Univ., 69 - Villeurbanne (France))

1991-03-01

In order to understand the differences existing between films obtained with a classical molecular beam deposition (MBD) and the new low-energy cluster beam deposition (LECBD), transmission electron microscopy has been used to characterize the first stages of antimony LECBD. Antimony deposits are discontinuous and amorphous up to 2 nm in thickness. They are formed with isolated amorphous antimony particles surrounded by an amorphous antimony oxide shell. Moreover, under electron beam exposure in the microscope, an amorphous-crystal transformation has been observed in the oxide shell. Electron irradiation induces the formation of a crystallized antimony oxide (Sb{sub 2}O{sub 3}) around the amorphous antimony core. (author).

Investigation of antimony extraction from nitric acid solutions by tributyl phosphate

International Nuclear Information System (INIS)

Lakaev, V.S.; Smelov, V.S.

1988-01-01

The effect of iodide, hydrogen and pertechnetate ions on antimony extraction by tri-n-butyl phosphate (TBP) from aqueous nitric acid solutions under irradiated nuclear fuel processing is investigated at room temperature. The coefficients of antimony distribution are shown to increase at the presence of technetium ions 2-3 times and iodine ions - 100 and more times. Variation of hydrogen ion concentration does not affect antimony extraction. The schemes of the mechanism of antimony extraction at the pressence of iodide and pertechnetate ions are presented. Compositions of the formed compounds are given

Thermodynamic analysis of separating lead and antimony in chloride system

Institute of Scientific and Technical Information of China (English)

CHEN Jin-zhong; CAO Hua-zhen; LI Bo; YUAN Hai-jun; ZHENG Guo-qu; YANG Tian-zu

2009-01-01

In chloride system, thermodynamic analysis is a useful guide to separate lead and antimony as well as to understand the separation mechanism. An efficient and feasible way for separating lead and antimony was discussed. The relationships of [Pb2+][Cl-]2-lg[Cl]T and E-lg[Cl]T in Pb-Sb-Cl-H2O system were studied, and the solubilities of lead chloride at different antimony concentrations were calculated based on principle of simultaneous equilibrium. The results show that insoluble salt PbCl2 will only exist stably in a certain concentration range of chlorine ion. This concentration range of chlorine ion expands a little with increasing the concentration of antimony in the system while narrows as the system acidity increases. The solubility of Pb2+ in solution decreases with increasing the concentration of antimony in the system, whereas increases with increasing the concentration of total chlorine. The concentration range of total chlorine causing lead solubility less than 0.005 mol/L increases monotonically.

Assessment of Industrial Antimony Exposure and Immunologic Function for Workers in Taiwan.

Science.gov (United States)

Wu, Chin-Ching; Chen, Yi-Chun

2017-06-26

This study investigated antimony exposure among employees in industries in Taiwan and evaluated whether their immunologic markers were associated with antimony exposure. We recruited 91 male workers and 42 male office administrators from 2 glass manufacturing plants, 1 antimony trioxide manufacturing plants, and 2 engineering plastic manufacturing plants. Air samples were collected at worksites and administrative offices, and each participant provided specimens of urine, blood, and hair to assay antimony levels. We also determined white blood cells, lymphocyte, and monocyte, IgA, IgE, and IgG in blood specimens. The mean antimony concentration in the air measured at worksites was much higher in the antimony trioxide plant (2.51 ± 0.57 mg/m³) than in plastic plants (0.21 ± 0.06 mg/m³) and glass plants (0.14 ± 0.01 mg/m³). Antimony levels in blood, urine, and hair measured for participants were correlated with worksites and were higher in workers than in administrators. The mean serum IgG, IgA, and IgE levels were lower in workers than in administrators ( p industrial plants than for administrators. This study suggests serum IgG, IgA, and IgE levels are negatively associated with antimony exposure.

Controls on the Mobility of Antimony in Mine Waste from Three Deposit Types

Science.gov (United States)

Jamieson, H.; Radková, A. B.; Fawcett, S.

2017-12-01

Antimony can be considered both a critical metal and an environmental hazard, with a toxicity similar to arsenic. It is concentrated in stibnite deposits, but also present in polymetallic and precious metal ores, frequently accompanied by arsenic. We have studied the mineralogical controls on the mobility of antimony in three types of mine waste: stibnite tailings from an antimony mine, tetrahedrite-bearing waste rock from copper mining, and gold mine tailings and ore roaster waste. Our results demonstrate that the tendency of antimony to leach into the aqueous environment or remain sequestered in solid phases depends on the primary host minerals and conditions governing the precipitation of secondary antimony-hosting phases. In tailings at the Beaver Brook antimony mine in Newfoundland, Canada, stibnite oxidizes rapidly, and secondary minerals such as the relatively insoluble Sb-Fe tripuhyite-like phase and Sb-bearing goethite. However, under dry conditions, the most important secondary Sb host is the Mg-Sb hydroxide brandholzite, but this easily soluble mineral disappears when it rains. Antimony that was originally hosted in tetrahedrite, a complex multi-element sulfosalt, in the historic waste rock piles at Špania Dolina-Piesky, Slovakia, is not as mobile as Cu and As during weathering but reprecipiates to a mixture of tripuhyite and romeite. Finally, the original antimony-hosting minerals, both stibnite and sulphosalts, in the gold ore at Giant Mine, Yellowknife, Canada were completely destroyed during ore roasting. In tailings-contaminated sediments, antimony persists in roaster-generated iron oxide phases, except under reducing conditions where some of the antimony forms a Sb-S phase. The combined presence of antimony and arsenic in mine waste complicates risk assessment but in general, our findings suggest that antimony is less mobile than arsenic in the environment.

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....

Behaviour of antimony during thermal treatment of Sb-rich halogenated waste

International Nuclear Information System (INIS)

Klein, J.; Dorge, S.; Trouve, G.; Venditti, D.; Durecu, S.

2009-01-01

Antimony compounds have a wide range of industrial applications, particularly as additives in flame retardants. To ensure environmentally friendly waste incineration of Sb-rich wastes, it is essential to strengthen the knowledge about the fate of antimony and the potential formation of harmful species. Investigations should be conducted particularly in relation with the main operational parameters controlling the process, chiefly temperature, residence time and air supply in the oven and in the post-combustion zone, prior final adapted cleaning of the flue-gas stream. Experimental studies focusing on antimony behaviour were undertaken through laboratory-scale thermal treatment at 850 deg. C and 1100 deg. C of a Sb-rich halogenated waste, originating from the sector of flame retardants formulation. The configuration of our laboratory experimental device allowed to achieve only low oxidative conditions in the waste bed, but high oxidative strength coupled with high temperature and sufficient gas residence time in the post-combustion zone, as prescribed during the incineration of hazardous wastes. Atomic absorption spectroscopy was used to assess the partition of antimony in the different compartments of the process. The oxidation degree of antimony in the gas-phase was determined by the use of electrochemical techniques, namely polarography coupled with anodic stripping voltamperometry. The partition of antimony between the residual ash and the gas-phase under moderate oxidative conditions in the waste bed was constant, whatever the temperature: the volatilization rate for antimony was ∼64%, while a ∼36% fraction remained in the residual bottom ashes. But interestingly, while at 850 o C, antimony was mainly present in the gas-phase at a +III oxidation degree, an increase in temperature of 250 o C favoured the presence of antimony to its highest oxidation degree +V in the flue-gas stream, a valence known to be involved in less toxic species.

Behaviour of antimony during thermal treatment of Sb-rich halogenated waste

Energy Technology Data Exchange (ETDEWEB)

Klein, J. [Laboratoire Gestion des Risques et Environnement, 25 rue de Chemnitz, 68200 Mulhouse (France); Dorge, S., E-mail: sophie.dorge@uha.fr [Laboratoire Gestion des Risques et Environnement, 25 rue de Chemnitz, 68200 Mulhouse (France); Trouve, G. [Laboratoire Gestion des Risques et Environnement, 25 rue de Chemnitz, 68200 Mulhouse (France); Venditti, D.; Durecu, S. [TREDI Departement de Recherche, Technopole de Nancy-Brabois, 9 avenue de la Foret de Haye, BP 184, 54505 Vandoeuvre-les-Nancy (France)

2009-07-30

Antimony compounds have a wide range of industrial applications, particularly as additives in flame retardants. To ensure environmentally friendly waste incineration of Sb-rich wastes, it is essential to strengthen the knowledge about the fate of antimony and the potential formation of harmful species. Investigations should be conducted particularly in relation with the main operational parameters controlling the process, chiefly temperature, residence time and air supply in the oven and in the post-combustion zone, prior final adapted cleaning of the flue-gas stream. Experimental studies focusing on antimony behaviour were undertaken through laboratory-scale thermal treatment at 850 deg. C and 1100 deg. C of a Sb-rich halogenated waste, originating from the sector of flame retardants formulation. The configuration of our laboratory experimental device allowed to achieve only low oxidative conditions in the waste bed, but high oxidative strength coupled with high temperature and sufficient gas residence time in the post-combustion zone, as prescribed during the incineration of hazardous wastes. Atomic absorption spectroscopy was used to assess the partition of antimony in the different compartments of the process. The oxidation degree of antimony in the gas-phase was determined by the use of electrochemical techniques, namely polarography coupled with anodic stripping voltamperometry. The partition of antimony between the residual ash and the gas-phase under moderate oxidative conditions in the waste bed was constant, whatever the temperature: the volatilization rate for antimony was {approx}64%, while a {approx}36% fraction remained in the residual bottom ashes. But interestingly, while at 850 {sup o}C, antimony was mainly present in the gas-phase at a +III oxidation degree, an increase in temperature of 250 {sup o}C favoured the presence of antimony to its highest oxidation degree +V in the flue-gas stream, a valence known to be involved in less toxic species.

First principles calculation of two dimensional antimony and antimony arsenide

Energy Technology Data Exchange (ETDEWEB)

Pillai, Sharad Babu, E-mail: sbpillai001@gmail.com; Narayan, Som; Jha, Prafulla K. [Department. of Physics, Faculty of Science, The M. S. University of Baroda, Vadodara-390002 (India); Dabhi, Shweta D. [Department of Physics, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar-364001 (India)

2016-05-23

This work focuses on the strain dependence of the electronic properties of two dimensional antimony (Sb) material and its alloy with As (SbAs) using density functional theory based first principles calculations. Both systems show indirect bandgap semiconducting character which can be transformed into a direct bandgap material with the application of relatively small strain.

Heavy weight vehicle traffic and its relationship with antimony content in human blood.

Science.gov (United States)

Quiroz, Waldo; De Gregori, Ida; Basilio, Paola; Bravo, Manuel; Pinto, Marcela; Lobos, Maria Gabriela

2009-05-01

Brake pads systems are nowadays considered as one of the most important sources of antimony in airborne particulate matter. One way that antimony can enter the body is through the lungs and specially by the interaction of antimony with -SH groups present in erythrocyte membrane cells. In spite of that, there are no studies about antimony enrichment in blood of workers exposed to high vehicle traffic. Port workers are generally exposed to heavy weight vehicle traffic. In Chile the biggest marine port is found in Valparaíso City. In this study antimony in whole blood and its fractions (erythrocytes-plasma and erythrocytes membranes-cytoplasm) of 45 volunteers were determined. The volunteers were port workers from Valparaíso city, and two control groups, one from Valparaíso and another from Quebrada Alvarado, the latter being a rural area located about 100 Km away from Valparaíso. The results demonstrate that port workers are highly impacted by antimony emissions from heavy weight vehicle traffic showing an average concentration of 27 +/- 9 ng Sb kg(-1), 5-10 times higher than the concentration of antimony in the blood of control groups. These are the highest antimony levels in blood ever reported in the literature. The highest antimony percentages (>60%) were always found in the erythrocyte fractions. However, the exposure degree to vehicle traffic is significant over antimony distribution in plasma, erythrocytes and cytoplasm. This results shows that the antimony mass in the erythrocyte membranes, was approximately constant at 1.0 +/- 0.1 ng Sb g(-1) of whole blood in all blood samples analyzed.

Determination of phosphorus contamination during antimony implantation by measurement and simulation

International Nuclear Information System (INIS)

Kuruc, M.; Hulenyi, L.; Kinder, R.

2006-01-01

Experimental determination of phosphorus cross-contamination during antimony implantation is presented. As a suitable structure for this experiment, a buried layer was employed which is created by implanting antimony followed by a long diffusion process. The samples implanted in different implanters were analysed by secondary ion mass spectrometry (SIMS), four-point probe and spreading resistance methods. The obtained results were compared with those calculated by program SUPREM-IV. Methods that can and cannot be used to determine phosphorus contamination during antimony implantation and to estimate the fluence of phosphorus being co-implanted with antimony are described in detail

Self-standing nanoribbons of antimony selenide and antimony sulfide with well-defined size and band gap

International Nuclear Information System (INIS)

Vadapoo, Rajasekarakumar; Krishnan, Sridevi; Yilmaz, Hulusi; Marin, Carlos

2011-01-01

Sub-10 nm semiconducting nanostructures are crucial for the realization of nanoscale devices. Fabrication of nanostructures at this scale with homogeneous properties is challenging. Using ab initio calculations, we show that self-standing ribbons of antimony selenide and antimony sulfide of width 1.1 nm exhibit well-defined bandgaps of 1.66 and 2.16 eV, respectively. Molecular dynamics studies show that these ribbons are stable at 500 K. The one-dimensional (1D) heterostructure of these nanoribbons (Sb 2 Se 3 /Sb 2 S 3 ) along the [001] direction shows a straddling type behavior.

Increased thiol levels in antimony-resistant Leishmania infantum isolated from treatment-refractory visceral leishmaniasis in Brazil.

Science.gov (United States)

Magalhães, Lucas S; Bomfim, Lays Gs; Mota, Sthefanne G; Cruz, Geydson S; Corrêa, Cristiane B; Tanajura, Diego M; Lipscomb, Michael W; Borges, Valéria M; Jesus, Amélia R de; Almeida, Roque P de; Moura, Tatiana R de

2018-02-01

BACKGROUND Treatment-refractory visceral leishmaniasis (VL) has become an important problem in many countries. OBJECTIVES We evaluated the antimony-resistance mechanisms of Leishmania infantum isolated from VL patients refractory or responsive to treatment with pentavalent antimony. METHODS Strains isolated from antimony-refractory patients (in vitro antimony-resistant isolates) and antimony-responsive patients (in vitro antimony-sensitive isolates) were examined. Morphological changes were evaluated by transmission electron microscopy after trivalent antimony exposure. P-glycoprotein (P-gp) efflux pump activity was evaluated using the pump-specific inhibitor verapamil hydrochloride, and the role of thiol in trivalent antimony resistance was investigated using the enzymatic inhibitor L-buthionine sulfoximine. FINDINGS Antimony treatment induced fewer alterations in the cellular structure of L. infantum resistant isolates than in that of sensitive isolates. P-gp efflux activity was not involved in antimony resistance in these isolates. Importantly, the resistant isolates contained higher levels of thiol compared to the sensitive isolates, and inhibition of thiol synthesis in the resistant isolates recovered their sensitivity to trivalent antimony treatment, and enhanced the production of reactive oxygen species in promastigotes exposed to the drug. MAIN CONCLUSIONS Our results demonstrate that isolates from patients with antimony-refractory VL exhibited higher thiol levels than antimony-sensitive isolates. This indicates that redox metabolism plays an important role in the antimony-resistance of New World VL isolates.

Effects of antimony additions on the fracture of nickel at 600 C

International Nuclear Information System (INIS)

White, C.L.; Padgett, R.A.

1983-01-01

Antimony additions (about 1 wt pct) are found to drastically lower tensile ductility and induce extensive intergranular cracking in nickel at 600 C. This effect is most pronounced at lower strain rates. These results are contrasted to results for pure nickel where ductility is high and failure occurs via plastic instability. Scanning electron microscopy revealed faceting of crack and cavity surfaces in the antimony doped nickel. Auger electron spectroscopy revealed segregation of antimony and (residual) sulfur to both grain boundaries and to the internal free surfaces of cracks and cavities. Inert ion sputter profiling showed that most of the antimony and sulfur enrichment on these surfaces is confined within a few atom layers of the interface. The embrittling influence of antimony is discussed in terms of the observed antimony and sulfur segregation to internal interfaces. Possible connections between the segregation and the observed embrittlement involve segregation effects on grain boundary sliding, grain boundary and surface diffusivities, and interfacial energetics

Complex processing of antimony-mercury gold concentrates of Dzhizhikrut Deposit

International Nuclear Information System (INIS)

Abdusalyamova, M.N.; Gadoev, S.A.; Dreisinger, D.; Solozhenkin, P.M.

2013-01-01

Present article is devoted to complex processing of antimony-mercury gold concentrates of Dzhizhikrut Deposit. The purpose of research was obtaining the metallic mercury and antimony with further gold and thallium extraction.

Protection of cesium-antimony photocathodes

International Nuclear Information System (INIS)

Buzulutskov, A.; Breskin, A.; Chechik, R.; Prager, M.; Shefer, E.

1996-06-01

In order to operate gaseous photomultipliers in the visible range it was suggested to protect sensitive photocathodes against contact to air and counting gases by their coating with a thin solid dielectric film. We present data on coating of cesium- antimony photocathodes with alkali-halide (NaI, CsI, CsF, NaF), oxide (SiO) and organic (hexatriacontane, calcium stearate) films. The photoelectron transmission through these films and their protection capability have been studied in detail. Cesium-antimony photocathodes are shown to withstand exposure to considerable doses of oxygen and dry air when coated with Nal films. This opens ways to their operation in gas media. (authors), 11 refs., 6 figs

Correlation of CsK2Sb photocathode lifetime with antimony thickness

Energy Technology Data Exchange (ETDEWEB)

Mamun, M. A. [Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, Virginia 23529, USA; The Applied Research Center, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA; Hernandez-Garcia, C. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA; Poelker, M. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA; Elmustafa, A. A. [Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, Virginia 23529, USA; The Applied Research Center, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA

2015-06-01

CsK2Sb photocathodes with quantum efficiency on the order of 10% at 532 nm, and lifetime greater than 90 days at low voltage, were successfully manufactured via co-deposition of alkali species emanating from an effusion source. Photocathodes were characterized as a function of antimony layer thickness and alkali consumption, inside a vacuum chamber that was initially baked, but frequently vented without re-baking. Photocathode lifetime measured at low voltage is correlated with the antimony layer thickness. Photocathodes manufactured with comparatively thick antimony layers exhibited the best lifetime. We speculate that the antimony layer serves as a reservoir, or sponge, for the alkali.

Correlation of CsK2Sb photocathode lifetime with antimony thickness

Directory of Open Access Journals (Sweden)

M. A. Mamun

2015-06-01

Full Text Available CsK2Sb photocathodes with quantum efficiency on the order of 10% at 532 nm, and lifetime greater than 90 days at low voltage, were successfully manufactured via co-deposition of alkali species emanating from an effusion source. Photocathodes were characterized as a function of antimony layer thickness and alkali consumption, inside a vacuum chamber that was initially baked, but frequently vented without re-baking. Photocathode lifetime measured at low voltage is correlated with the antimony layer thickness. Photocathodes manufactured with comparatively thick antimony layers exhibited the best lifetime. We speculate that the antimony layer serves as a reservoir, or sponge, for the alkali.

Speciation of antimony in polyethylene terephthalate bottles

International Nuclear Information System (INIS)

Martin, R.R.; Ablett, J.; Shotyk, W.S.; Naftel, S.; Northrup, P.

2010-01-01

Antimony contamination has been reported in drinking water from polyethylene terephthalate (PET) bottles. Micro-X-ray fluorescence (XRF) analysis has been used to identify the distribution and chemical form of residual antimony used as a catalyst in the manufacture of PET bottles. The results are consistent with clusters of Sb(III) having dimensions of the order of tens of micrometers, clearly showing the ability of synchrotron radiation analyses to both map elemental distribution and determine oxidation state.

Tissue distribution of residual antimony in rats treated with multiple doses of meglumine antimoniate

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Deise Riba Coelho

2014-07-01

Full Text Available Meglumine antimoniate (MA and sodium stibogluconate are pentavalent antimony (SbV drugs used since the mid-1940s. Notwithstanding the fact that they are first-choice drugs for the treatment of leishmaniases, there are gaps in our knowledge of their toxicological profile, mode of action and kinetics. Little is known about the distribution of antimony in tissues after SbV administration. In this study, we evaluated the Sb content of tissues from male rats 24 h and three weeks after a 21-day course of treatment with MA (300 mg SbV/kg body wt/d, subcutaneous. Sb concentrations in the blood and organs were determined by inductively coupled plasma-mass spectrometry. In rats, as with in humans, the Sb blood levels after MA dosing can be described by a two-compartment model with a fast (t1/2 = 0.6 h and a slow (t1/2 >> 24 h elimination phase. The spleen was the organ that accumulated the highest amount of Sb, while bone and thyroid ranked second in descending order of tissues according to Sb levels (spleen >> bone, thyroid, kidneys > liver, epididymis, lungs, adrenals > prostate > thymus, pancreas, heart, small intestines > skeletal muscle, testes, stomach > brain. The pathophysiological consequences of Sb accumulation in the thyroid and Sb speciation in the liver, thyroid, spleen and bone warrant further studies.

Synthesis, characterisation and electrochemical evaluation of reduced graphene oxide modified antimony nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Silwana, Bongiwe; Horst, Charlton van der [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa); SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Iwuoha, Emmanuel [SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Somerset, Vernon, E-mail: vsomerset@csir.co.za [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa)

2015-10-01

This paper demonstrates some aspects on the synthesis and characterisation of nanoparticles of metallic alloys using polyvinyl alcohol as a stabiliser, which combines high surface area and superior hybrid properties. The present experimental design was to synthesise a nanocomposite of reduced graphene oxide and antimony nanoparticles to be used as thin films for macro- and micro-carbon electrodes for enhancing sensing of different toxic metal pollutants in the environment. The synthetic process of reduced graphene oxide was done using the modified Hummers method while antimony pentachloride was reduced with sodium borohydride into nanoparticles of antimony using polyvinyl-alcohol as a stabiliser. The systematic investigation of morphology was done by scanning electron microscopy and high resolution-transmission electron microscope, which revealed the synthesis of a product, consists of reduced graphene oxide antimony nanoparticles. The electrochemical behaviour of the reduced graphene oxide antimony nanoparticles coated on a glassy carbon electrode was performed using voltammetric and impedance techniques. Electrochemical impedance measurements showed that the overall resistance, including the charge–transfer resistance, was smaller with reduced graphene oxide antimony nanoparticles than reduced graphene oxide and antimony nanoparticles, on their own. Evaluation of the reduced graphene oxide antimony nanoparticle sensor in the stripping voltammetry has shown a linear working range for concentration of platinum (II) between 6.0 × 10{sup −6}–5.4 × 10{sup −5} μg L{sup −1} with limit of detection of 6 × 10{sup −6} μg L{sup −1} (signal-to-noise ratio = 3), which is below the World Health Organisation guidelines for freshwater. - Highlights: • Reduced graphene oxide modified antimony nanoparticles were chemically synthesised. • TEM results show rGO-Sb nanoparticles with a diameter range of between 2 and 20 nm. • Impedance results confirm

The presence of antimony in various dental filling materials

International Nuclear Information System (INIS)

Molokhia, Anat; Combe, E.C.; Lilley, J.D.

1985-01-01

Antimony was determined in a number of non-metallic dental materials currently used for tooth restoration. The method applied was instrumental neutron activation analysis. The concentration of antimony in some of the brands tested was found to be as high as 900 fold that in the normal hard dental tissues. (author)

Sorbents for effective removal of radioactive antimony during chemical decontamination

International Nuclear Information System (INIS)

Nishad, Padala Abdul; Bhaskarapillai, Anupkumar; Velmurugan, Sankaralingam

2014-01-01

Removal of radioactive antimony is a challenging problem. Often, during decontamination, they get mobilized around the system and redeposit in different areas thus offsetting the reduction in the radiation field obtained by removing other activities such as 60 Co. Thus, there is a clear need for better antimony removing materials/strategies for effective reactor decontamination. In this regard, six commercially available sorbents namely, Tulsion A33 (strong base anion (-OH) resin), Amberlite IRC-718 (chelating resin), Radex ® Sb-1000, nano TiO 2 -special grade (Inorganic type IX), Chitosan (biosorbent) and Aeroxide p25 (nano TiO 2 , Inorganic type IX) were evaluated for their antimony sorption properties. Radex ® and TiO 2 based materials were found to be more effective in removing both Sb(V) and Sb(III). Solution pH was seen to significantly influence the antimony sorption and the effect was more prominent in anion resin, when tested under column conditions. Apart from the commercial sorbents, we have synthesised a robust high performing sorbent (TA-Chitosan beads) in the form of stable beads, using nano-TiO 2 and chitosan. The beads were found to retain the antimony sorption properties of the nano-TiO 2 , while adapting a physical format suitable for large scale operations. The sorbent exhibited almost complete sorption of antimony both in low (ppb level) as well as high concentrations of antimony. The suitability of the beads for use in column mode has been established and its radiation stability was probed in detail. The beads were found to be stable to irradiations as ascertained from the TOC values and unchanged sorption properties. The sorption properties of the CHITA beads in typical decontamination formulation containing mixture of complexing agents have been investigated in detail. (author)

Antimony susceptibility of Leishmania isolates collected over a 30-year period in Algeria.

Science.gov (United States)

Eddaikra, Naouel; Ait-Oudhia, Khatima; Kherrachi, Ihcen; Oury, Bruno; Moulti-Mati, Farida; Benikhlef, Razika; Harrat, Zoubir; Sereno, Denis

2018-03-01

In Algeria, the treatment of visceral and cutaneous leishmanioses (VL and CL) has been and continues to be based on antimony-containing drugs. It is suspected that high drug selective pressure might favor the emergence of chemoresistant parasites. Although treatment failure is frequently reported during antimonial therapy of both CL and VL, antimonial resistance has never been thoroughly investigated in Algeria. Determining the level of antimonial susceptibility, amongst Leishmania transmitted in Algeria, is of great importance for the development of public health policies. Within the framework of the knowledge about the epidemiology of VL and CL amassed during the last 30 years, we sampled Leishmania isolates to determine their susceptibility to antimony. We analyzed a total of 106 isolates including 88 isolates collected between 1976 and 2013 in Algeria from humans, dogs, rodents, and phlebotomines and 18 collected from dogs in France. All the Algerian isolates were collected in 14 localities where leishmaniasis is endemic. The 50% inhibitory concentrations (IC50) of potassium antimony tartrate (the trivalent form of antimony, Sb(III)) and sodium stibogluconate (the pentavalent form of antimony, Sb(V)) were determined in promastigotes and intramacrophage amastigotes, respectively. The epidemiological cutoff (ECOFF) that allowed us to differentiate between Leishmania species causing cutaneous or visceral leishmaniases that were susceptible (S+) or insusceptible (S-) to the trivalent form of antimony was determined. The computed IC50 cutoff values were 23.83 μg/mL and 15.91 μg/mL for VL and CL, respectively. We report a trend of increasing antimony susceptibility in VL isolates during the 30-year period. In contrast, an increase in the frequency of S- phenotypes in isolates causing CL was observed during the same period. In our study, the emergence of S- phenotypes correlates with the inclusion of L. killicki (syn: L. tropica) isolates that cause cutaneous

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.

Simple and effective method for nuclear tellurium isomers separation from antimony cyclotron targets

International Nuclear Information System (INIS)

Bondarevskij, S.I.; Eremin, V.V.

1999-01-01

Simple and effective method of generation of tellurium nuclear isomers from irradiated on cyclotron metallic antimony is suggested. Basically this method consists in consideration of the big difference in volatilities of metallic forms of antimony, tin and tellurium. Heating of the tin-antimony alloy at 1200 K permits to separate about 90 % of produced quantity of 121m Te and 123m Te (in this case impurity of antimony radionuclides is not more than 1 % on activity) [ru

Structural and electrical characterization of zinc oxide doped with antimony

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G. Juárez Díaz

2014-08-01

Full Text Available In this work we report the results of structural and electrical characterization realized on zinc oxide single crystal samples with (001 orientation, which were doped with antimony. Doping was carried out by antimony thermal diffusion at 1000 °C for periods of 1 and 2 hours under nitrogen environment from a solid source formed by antimony oxide. Electrical characterization by I-V curves and Hall effect shown an increase in acceptor concentration which demonstrates that doping is effective and create holes in zinc oxide samples.

Antimony Resistance in Leishmania, Focusing on Experimental Research

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Fakhri Jeddi

2011-01-01

Full Text Available Leishmaniases are parasitic diseases that spread in many countries with a prevalence of 12 million cases. There are few available treatments and antimonials are still of major importance in the therapeutic strategies used in most endemic regions. However, resistance toward these compounds has recently emerged in areas where the replacement of these drugs is mainly limited by the cost of alternative molecules. In this paper, we reviewed the studies carried out on antimonial resistance in Leishmania. Several common limitations of these works are presented before prevalent approaches to evidence antimonial resistance are related. Afterwards, phenotypic determination of resistance is described, then confronted to clinical outcome. Finally, we detail molecular mechanisms and targets involved in resistance and already identified in vitro within selected mutant strains or in clinical isolates.

Removing antimony from waste lead storage batteries alloy by vacuum displacement reaction technology.

Science.gov (United States)

Liu, Tiantian; Qiu, Keqiang

2018-04-05

With the wide application of lead acid battery, spent lead acid battery has become a serious problem to environmental protection and human health. Though spent battery can be a contaminant if not handled properly, it is also an important resource to obtain refined lead. Nowadays, the Sb-content in lead storage batteries is about 0.5-3 wt%, which is higher than the Sb-content in the crude lead. However, there are few reports about the process of removing antimony from high-antimony lead bullion. In this study, vacuum displacement reaction technology, a new process for removing antimony from high-antimony lead melts, was investigated. During this process, lead oxide was added to the system and antimony from lead melts was converted into antimony trioxide, which easily was evaporated under vacuum so that antimony was removed from lead melts. The experimental results demonstrated that Sb-content in lead melts decreased from 2.5% to 23 ppm under following conditions: mass ratio of PbO/lead bullion of 0.33, residual gas pressure of 30 Pa, melt temperature of 840 °C, reaction time of 60 min. The distillate gotten can be used as by-product to produce antimony white. Moreover, this study is of importance to recycling of waste lead storage batteries alloy. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of antimony trioxide in fire-retardant conveyor belts

Energy Technology Data Exchange (ETDEWEB)

Rytych-Witwicka, B.; Szmyd, E.

1976-12-01

Two methods for the determination of antimony trioxide in rubber and pvc are described. One is a colorimetric method based on the reaction of antimony with rhodamine B; the other is a polarographic method. The results of the two methods show a satisfactory consistency and the methods themselves appear rapid and effective.

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 ...

Complexation of HSA with different forms of antimony (Sb): An application of fluorescence spectroscopy

International Nuclear Information System (INIS)

Song, Wenjuan; Zhang, Daoyong; Pan, Xiangliang; Lee, Duu-Jong

2013-01-01

Antimony (Sb) pollution has been of a great environmental concern in some areas in China. Sb enters human body via drinking water, inhalation and food chain, unavoidably interacts with human serum albumin (HSA) in blood plasma, and consequently does harm to human health. The harmful effects of Sb on human health depend on the Sb species and their binding ability to HSA. In the present study, binding of three forms of Sb with HSA was investigated by excitation-emission matrix (EEM) spectroscopy. All of antimony potassium tartrate, antimony trichloride and potassium pyroantimonate quenched fluorescence of HSA. Values of conditional stability constant K a (×10 5 /M) for Sb and HSA systems were 8.13–9.12 for antimony potassium tartrate, 2.51–4.27 for antimony trichloride and 3.63–9.77 for potassium pyroantimonate. The binding constant K b (×10 4 /M) values of HSA with antimony potassium tartrate, antimony trichloride and potassium pyroantimonate were 0.02–0.07, 3.55–5.01, and 0.07–1.08, respectively. There was one independent class of binding site for antimony trichloride towards HSA. There was more than one Sb binding site and negative cooperativity between multiple binding sites for potassium pyroantimonate and antimony potassium tartrate towards HSA. The binding ability of HSA to complex Sb followed the order: antimony trichloride>potassium pyroantimonate>antimony potassium tartrate. -- Highlights: ► The first study reporting interaction of Sb with HSA. ► Sb can effectively quench the fluorescence of HSA. ► The binding ability of HSA to Sb was dependent on the form of Sb. ► Binding differences indicate differences in toxicity of various forms Sb to human. ► HAS-Sb binding parameters are important for understanding toxicity of Sb

Complexation of HSA with different forms of antimony (Sb): An application of fluorescence spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Song, Wenjuan [State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011 (China); Zhang, Daoyong [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002 (China); Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Pan, Xiangliang, E-mail: xlpan@ms.xjb.ac.cn [State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011 (China); Lee, Duu-Jong [State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011 (China); Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China)

2013-04-15

Antimony (Sb) pollution has been of a great environmental concern in some areas in China. Sb enters human body via drinking water, inhalation and food chain, unavoidably interacts with human serum albumin (HSA) in blood plasma, and consequently does harm to human health. The harmful effects of Sb on human health depend on the Sb species and their binding ability to HSA. In the present study, binding of three forms of Sb with HSA was investigated by excitation-emission matrix (EEM) spectroscopy. All of antimony potassium tartrate, antimony trichloride and potassium pyroantimonate quenched fluorescence of HSA. Values of conditional stability constant K{sub a} (×10{sup 5}/M) for Sb and HSA systems were 8.13–9.12 for antimony potassium tartrate, 2.51–4.27 for antimony trichloride and 3.63–9.77 for potassium pyroantimonate. The binding constant K{sub b} (×10{sup 4}/M) values of HSA with antimony potassium tartrate, antimony trichloride and potassium pyroantimonate were 0.02–0.07, 3.55–5.01, and 0.07–1.08, respectively. There was one independent class of binding site for antimony trichloride towards HSA. There was more than one Sb binding site and negative cooperativity between multiple binding sites for potassium pyroantimonate and antimony potassium tartrate towards HSA. The binding ability of HSA to complex Sb followed the order: antimony trichloride>potassium pyroantimonate>antimony potassium tartrate. -- Highlights: ► The first study reporting interaction of Sb with HSA. ► Sb can effectively quench the fluorescence of HSA. ► The binding ability of HSA to Sb was dependent on the form of Sb. ► Binding differences indicate differences in toxicity of various forms Sb to human. ► HAS-Sb binding parameters are important for understanding toxicity of Sb.

REACTION PRODUCTS AND CORROSION OF MOLYBDENUM ELECTRODE IN GLASS MELT CONTAINING ANTIMONY OXIDES AND SODIUM SULFATE

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JIŘÍ MATĚJ

2012-09-01

Full Text Available The products on the interface of a molybdenum electrode and glass melt were investigated primarily at 1400°C in three model glass melts without ingredients, with 1 % Sb2O3 and with 1 % Sb2O3 and 0.5 % SO3 (wt. %, both under and without load by alternating current. Corrosion of the molybdenum electrode in glass melt without AC load is higher by one order of magnitude if antimony oxides are present. The corrosion continues to increase if sulfate is present in addition to antimony oxides. Isolated antimony droplets largely occur on the electrode-glass melt interface, and numerous droplets are also dissipated in the surrounding glass if only antimony oxides are present in the glass melt. A comparatively continuous layer of antimony occurs on the interface if SO3 is also present, antimony being always in contact with molybdenum sulfide. Almost no antimony droplets are dissipated in the glass melt. The total amount of precipitated antimony also increases. The presence of sulfide on the interface likely facilitates antimony precipitation. The reaction of molybdenum with antimony oxides is inhibited in sites covered by an antimony layer. The composition of sulfide layers formed at 1400°C approximates that of Mo2S3. At 1100°C, the sulfide composition approximates that of MoS4. Corrosion multiplies in the glass melt without additions through the effect of AC current, most molybdenum being separated in the form of metallic particles. Corrosion also increases in the glass melt containing antimony oxides. This is due to increased corrosion in the neighborhood of the separated antimony droplets. This mechanism also results in the loosening of molybdenum particles. The amount of precipitated antimony also increases through the effect of the AC current. AC exerts no appreciable effect on either corrosion, the character of the electrode-glass interface, or antimony precipitation in the glass melt containing SO3.

Correlation of CsK{sub 2}Sb photocathode lifetime with antimony thickness

Energy Technology Data Exchange (ETDEWEB)

Mamun, M. A., E-mail: mmamu001@odu.edu; Elmustafa, A. A. [Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States); The Applied Research Center, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Hernandez-Garcia, C.; Poelker, M. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)

2015-06-01

CsK{sub 2}Sb photocathodes with quantum efficiency on the order of 10% at 532 nm, and lifetime greater than 90 days at low voltage, were successfully manufactured via co-deposition of alkali species emanating from an effusion source. Photocathodes were characterized as a function of antimony layer thickness and alkali consumption, inside a vacuum chamber that was initially baked, but frequently vented without re-baking. Photocathode lifetime measured at low voltage is correlated with the antimony layer thickness. Photocathodes manufactured with comparatively thick antimony layers exhibited the best lifetime. We speculate that the antimony layer serves as a reservoir, or sponge, for the alkali.

The Evaluation of the Corrosion Resistance of the Al-Si Alloys Antimony Alloyed

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Svobodova J.

2014-06-01

Full Text Available This paper deals with the evaluation of the corrosion resistance of the Al-Si alloys alloyed with the different amount of antimony. Specifically it goes about the alloy AlSi7Mg0,3 which is antimony alloyed in the concentrations 0; 0,001; 0,005; 0,01 a 0,05 wt. % of antimony. The introduction of the paper is dedicated to the theory of the aluminium alloys corrosion resistance, testing and evaluation of the corrosion resistance. The influence of the antimony to the Al-Si alloys properties is described further in the introduction. The experimental part describes the experimental samples which were prepared for the experiment and further they were exposed to the loading in the atmospheric conditions for a period of the 3 months. The experimental samples were evaluated macroscopically and microscopically. The results of the experiment were documented and the conclusions in terms of the antimony impact to the corrosion resistance of the Al-Si alloy were concluded. There was compared the corrosion resistance of the Al-Si alloy antimony alloyed (with the different antimony content with the results of the Al-Si alloy without the alloying after the corrosion load in the atmospheric conditions in the experiment.

Effect of antimony substitution in iron pnictide compounds

OpenAIRE

Schmidt, D.; Braun, H. F.

2015-01-01

In the present study we have examined the effect of negative chemical pressure in iron pnictides. We have synthesized substitution series replacing arsenic by antimony in a number of 1111- and 122-iron arsenides and present their crystallographic and physical properties. The SDW transition temperature in LaFeAs$_{\\mathrm{1-x}}$Sb$_{\\mathrm{x}}$O decreases with increasing antimony content, while the superconducting transition temperature in LaFeAs$_{\\mathrm{1-x}}$Sb$_{\\mathrm{x}}$O$_{\\mathrm{0...

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...

Efficiency of manganese dioxide for the removal of antimony from aqueous solutions

International Nuclear Information System (INIS)

Hasany, S.M.; Najamuddin; Ikram, M.

1993-01-01

The sorption of antimony onto manganese dioxide from aqueous solution has been investigated as a function of shaking time, composition of electrolyte, concentration of sorbent and sorbate, Maximum sorption of antimony has been achieved from deionized water after 15 minutes shaking at 45 cm/sup 3/g/sup -1/ V/W ratio. The influence of different anions and cations on the sorption has also been examined. EDTA, tartrate, citrate and Fe(II) decreased the sorption significantly. Among the metal ions tested only Se (IV) has shown strong sorption than antimony whereas Co(II), Hf (IV) and Te(IV) indicated low sorption affinity under similar experimental conditions. The sorption of antimony was also tested by different isotherms. The data fitted only to Freyndlich and D-R models. The sorption capacity of 7.71 m mole g/sup -1/, mean energy of sorption of 8.9 kJ mole/sup -1/ and of B = 0.00632 mole/sup 2/kJ/sup -2/ have been system. It is concluded that manganese dioxide can be used for the removal of antimony from industrial effluents and for its recovery from very dilute solutions. The oxide can also be applied for the separation of antimony, selenium and arsenic from Te(IV). (author)

Extended solubility and martensitic hcp nickel formation in antimony implanted nickel

International Nuclear Information System (INIS)

Johnson, E.; Sarholt-Kristensen, L.; Johansen, A.

1982-01-01

Radiation damage microstructure and associated disorder have been investigated in antimony implanted nickel crystals using combined RBS and TEM analyses. In crystals implanted at and below room temperature with 80 keV Sb + ions to a fluence of 5x10 20 m -2 , the retained antimony concentration in the implantation zone is approaching 15 at.%, with nearly all the antimony located substitutionally. The associated disorder as seen in the RBS analysis is insignificant. Annealing up to 600 0 C has little influence on the antimony distribution, whilst the dechanneling level is reduced. TEM and diffraction analysis of room temperature implanted samples show that the radiation damage consists of dense distributions of dislocation clusters and tangles, superimposed on a rather homogeneous background of new phase particles, identified as hcp nickel. The particles have a size 0.1-0.2 μm. The high substitutional antimony concentration at and below room temperature, which exceeds the solubility limit, indicates that its formation is thermally diffusionless and rather an effect of radiation enhanced solubility. The diffusionless nature of the microstructure is also indicated from the presence of martensitic hcp nickel, believed to form due to relief of radiation induced internal stress. (Auth.)

Distribution of liposome-encapsulated antimony in dogs

Directory of Open Access Journals (Sweden)

D.A. Schettini

2003-02-01

Full Text Available The achievement of complete cure in dogs with visceral leishmaniasis is currently a great challenge, since dogs are the main reservoir for the transmission of visceral leishmaniasis to humans and they respond poorly to conventional treatment with pentavalent antimonials. In order to improve the efficacy of treatment, we developed a novel formulation for meglumine antimoniate based on the encapsulation of this drug in freeze-dried liposomes (LMA. The aim of the present study was to evaluate the biodistribution of antimony (Sb in dogs following a single intravenous bolus injection of LMA. Four healthy male mongrel dogs received LMA at 3.8 mg Sb/kg body weight and were sacrificed 3, 48 and 96 h and 7 days later. Antimony was determined in the blood, liver, spleen and bone marrow. In the bone marrow, the highest Sb concentration was observed at 3 h (2.8 µg/g wet weight whereas in the liver and spleen it was demonstrated at 48 h (43.6 and 102.4 µg/g, respectively. In these organs, Sb concentrations decreased gradually and reached levels of 19.1 µg/g (liver, 28.1 µg/g (spleen and 0.2 µg/g (bone marrow after 7 days. Our data suggest that the critical organ for the treatment with LMA could be the bone marrow, since it has low Sb levels and, presumably, high rates of Sb elimination. A multiple dose treatment with LMA seems to be necessary for complete elimination of parasites from bone marrow in dogs with visceral leishmaniasis.

The promotion on cell growth of androgen-dependent prostate cancer by antimony via mimicking androgen activity.

Science.gov (United States)

Zhang, Changwen; Li, Penghao; Wen, Yingwu; Feng, Guowei; Liu, Yu; Zhang, Yangyi; Xu, Yong; Zhang, Zhihong

2018-05-15

Antimony is a widely used heavier pnictogens in industry, and its toxicity has been a matter of concern. Although previous studies have suggested that antimony may have the function as either a tumor suppressor or an oncogene in several cancers, the molecular basis underlying antimony-mediated transformation is still unclear. In the current study, we attempt to elucidate the potential role of antimony in the development of prostate cancer. Our results showed that the concentration of antimony was much higher in serum of prostate cancer patients, and was closely associated with poor outcome of patients who underwent radical prostatectomy. Additionally, low dose of antimony could promote proliferation and invasion of androgen-dependent prostate cancer cell line LNCaP cells in vitro and in vivo. The mechanistic studies demonstrated that exposure to antimony triggered the phosphorylation of androgen receptor (AR), which transcriptionally regulates the expression of androgen-related targets, including PSA and NKX3.1. Overall, our results unearthed that antimony could promote tumor growth by mimicking androgen activity in androgen-dependent prostate cancer cells. Therefore, these findings expanded our understanding on the molecular mechanism of antimony in tumorigenesis and tumor progression of prostate cancer, and it appears to be an inspiring strategy to restrain prostate cancer by inhibiting antimony-induced androgen-like effects. Copyright © 2018 Elsevier B.V. All rights reserved.

In Vitro Antiparasitic and Apoptotic Effects of Antimony Sulfide Nanoparticles on Leishmania infantum

Directory of Open Access Journals (Sweden)

Saied Soflaei

2012-01-01

Full Text Available Visceral leishmaniasis is one of the most important sever diseases in tropical and subtropical countries. In the present study the effects of antimony sulfide nanoparticles on Leishmania infantum in vitro were evaluated. Antimony sulfide NPs (Sb2S5 were synthesized by biological method from Serratia marcescens bacteria. Then the cytotoxicity effects of different concentrations (5, 10, 25, 50, and 100 μg/mL of this nanoparticle were assessed on promastigote and amastigote stages of L. infantum. MTT method was used for verification results of promastigote assay. Finally, the percentages of apoptotic, necrotic, and viable cells were determined by flow cytometry. The results indicated the positive effectiveness of antimony sulfide NPs on proliferation of promastigote form. The IC50 (50% inhibitory concentration of antimony sulfide NPs on promastigotes was calculated 50 μg/mL. The cytotoxicity effect was dose-dependent means by increasing the concentration of antimony sulfide NPs, the cytotoxicity curve was raised and the viability curve of the parasite dropped simultaneously. Moreover, the IC50 of antimony sulfide NPs on amastigote stage was calculated 25 μg/mL. On the other hand, however, antimony sulfide NPs have a low cytotoxicity effect on uninfected macrophages but it can induce apoptosis in promastigote stage at 3 of 4 concentrations.

Leishmania donovani isolates with antimony-resistant but not -sensitive phenotype inhibit sodium antimony gluconate-induced dendritic cell activation.

Directory of Open Access Journals (Sweden)

Arun Kumar Haldar

2010-05-01

Full Text Available The inability of sodium antimony gluconate (SAG-unresponsive kala-azar patients to clear Leishmania donovani (LD infection despite SAG therapy is partly due to an ill-defined immune-dysfunction. Since dendritic cells (DCs typically initiate anti-leishmanial immunity, a role for DCs in aberrant LD clearance was investigated. Accordingly, regulation of SAG-induced activation of murine DCs following infection with LD isolates exhibiting two distinct phenotypes such as antimony-resistant (Sb(RLD and antimony-sensitive (Sb(SLD was compared in vitro. Unlike Sb(SLD, infection of DCs with Sb(RLD induced more IL-10 production and inhibited SAG-induced secretion of proinflammatory cytokines, up-regulation of co-stimulatory molecules and leishmanicidal effects. Sb(RLD inhibited these effects of SAG by blocking activation of PI3K/AKT and NF-kappaB pathways. In contrast, Sb(SLD failed to block activation of SAG (20 microg/ml-induced PI3K/AKT pathway; which continued to stimulate NF-kappaB signaling, induce leishmanicidal effects and promote DC activation. Notably, prolonged incubation of DCs with Sb(SLD also inhibited SAG (20 microg/ml-induced activation of PI3K/AKT and NF-kappaB pathways and leishmanicidal effects, which was restored by increasing the dose of SAG to 40 microg/ml. In contrast, Sb(RLD inhibited these SAG-induced events regardless of duration of DC exposure to Sb(RLD or dose of SAG. Interestingly, the inhibitory effects of isogenic Sb(SLD expressing ATP-binding cassette (ABC transporter MRPA on SAG-induced leishmanicidal effects mimicked that of Sb(RLD to some extent, although antimony resistance in clinical LD isolates is known to be multifactorial. Furthermore, NF-kappaB was found to transcriptionally regulate expression of murine gammaglutamylcysteine synthetase heavy-chain (mgammaGCS(hc gene, presumably an important regulator of antimony resistance. Importantly, Sb(RLD but not Sb(SLD blocked SAG-induced mgammaGCS expression in DCs by

Neutrons and antimony physical measurements and interpretations

International Nuclear Information System (INIS)

Smith, A. B.

2000-01-01

New experimental information for the elastic and inelastic scattering of ∼ 4--10 MeV neutrons from elemental antimony is presented. The differential measurements are made at ∼ 40 or more scattering angles and at incident neutron-energy intervals of ∼ 0.5 MeV. The present experimental results, those previously reported from this laboratory and as found in the literature are comprehensively interpreted using spherical optical-statistical and dispersive-optical models. Direct vibrational processes via core-excitation, isospin and shell effects are discussed. Antimony models for applications are proposed and compared with global, regional, and specific models reported in the literature

Lattice dynamics of femtosecond laser-excited antimony

Energy Technology Data Exchange (ETDEWEB)

Abdel-Fattah, Mahmoud Hanafy [Applied Research Center, Old Dominion University, Newport News, VA 23606 (United States); Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529 (United States); Bugayev, Aleksey [Applied Research Center, Old Dominion University, Newport News, VA 23606 (United States); Elsayed-Ali, Hani E., E-mail: helsayed@odu.edu [Applied Research Center, Old Dominion University, Newport News, VA 23606 (United States); Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529 (United States)

2016-07-01

Ultrafast electron diffraction is used to probe the lattice dynamics of femtosecond laser-excited antimony thin film. The temporal hierarchies of the intensity and position of diffraction orders are monitored. The femtosecond laser excitation of antimony film was found to lead to initial compression after the laser pulse, which gives way to tension vibrating at new equilibrium displacement. A damped harmonic oscillator model, in which the hot electron-blast force contributes to the driving force of oscillations in lattice spacing, is used to interpret the data. The electron–phonon energy-exchange rate and the electronic Grüneisen parameter were obtained.

Enrichment of Gold in Antimony Matte by Direct Smelting of Refractory Gold Concentrate

Science.gov (United States)

Yang, Tianzu; Xie, Boyi; Liu, Weifeng; Zhang, Duchao; Chen, Lin

2018-06-01

Conventional cyanidation technology achieves low gold recovery when used to process refractory gold concentrate. Based on the geochemical characteristics of gold deposit mineralization, a new method is proposed herein for gold enrichment in antimony matte by smelting of refractory gold concentrate. The effects of the FeO/SiO2 and CaO/SiO2 ratios, smelting temperature, and smelting time on the gold recovery were investigated in detail. The optimum conditions were determined to be FeO/SiO2 ratio of 1.2, CaO/SiO2 ratio of 0.4, smelting temperature of 1200°C, and smelting time of 45 min. The gold content in antimony matte and smelting slag was 96.68 and 1.13 g/t, respectively. The gold, antimony, and arsenic recovery was 97.72%, 26.89%, and 6.56%, respectively, with most of the antimony and arsenic volatilized into dust. Mineral liberation analyzer results showed that the antimony matte mainly consisted of FeS and FeO, with three phases, viz. FeAs, SbAs, and AuSb, embedded between them, indicating that gold was easily enriched with antimony and arsenic during smelting of refractory gold concentrate.

Enrichment of Gold in Antimony Matte by Direct Smelting of Refractory Gold Concentrate

Science.gov (United States)

Yang, Tianzu; Xie, Boyi; Liu, Weifeng; Zhang, Duchao; Chen, Lin

2018-04-01

Conventional cyanidation technology achieves low gold recovery when used to process refractory gold concentrate. Based on the geochemical characteristics of gold deposit mineralization, a new method is proposed herein for gold enrichment in antimony matte by smelting of refractory gold concentrate. The effects of the FeO/SiO2 and CaO/SiO2 ratios, smelting temperature, and smelting time on the gold recovery were investigated in detail. The optimum conditions were determined to be FeO/SiO2 ratio of 1.2, CaO/SiO2 ratio of 0.4, smelting temperature of 1200°C, and smelting time of 45 min. The gold content in antimony matte and smelting slag was 96.68 and 1.13 g/t, respectively. The gold, antimony, and arsenic recovery was 97.72%, 26.89%, and 6.56%, respectively, with most of the antimony and arsenic volatilized into dust. Mineral liberation analyzer results showed that the antimony matte mainly consisted of FeS and FeO, with three phases, viz. FeAs, SbAs, and AuSb, embedded between them, indicating that gold was easily enriched with antimony and arsenic during smelting of refractory gold concentrate.

Alkaline sulfide pretreatment of an antimonial refractory Au-Ag ore for improved cyanidation

Science.gov (United States)

Alp, Ibrahim; Celep, Oktay; Deveci, Haci

2010-11-01

This paper presents the alkaline sulfide pretreatment of an antimonial refractory gold and silver ore. In the ore, gold occurs mainly as gold-silver alloys and as associated with quartz and framboidal pyrite grains, and, to a small extent, as the inclusions within antimonial sulfides. Silver is present extensively as antimonial sulfides such as andorite. Alkaline sulfide pretreatment was shown to allow the decomposition of the antimonial sulfide minerals (up to 98% Sb removal) and to remarkably improve the amenability of gold (e.g., from leaching. An increase in reagent concentration (1-4 mol/L Na2S or NaOH) and temperature (20-80°C), and a decrease in particle size seem to produce an enhancing effect on metal extraction. These findings suggest that alkaline sulfide leaching can be suitably used as a chemical pretreatment method prior to the conventional cyanidation for antimonial refractory gold and silver ores.

Oligosilanylated Antimony Compounds

OpenAIRE

Zitz, Rainer; Gatterer, Karl; Reinhold, Crispin R. W.; M?ller, Thomas; Baumgartner, Judith; Marschner, Christoph

2015-01-01

By reactions of magnesium oligosilanides with SbCl3, a number of oligosilanylated antimony compounds were obtained. When oligosilanyl dianions were used, either the expected cyclic disilylated halostibine was obtained or alternatively the formation of a distibine was observed. Deliberate formation of the distibine from the disilylated halostibine was achieved by reductive coupling with C8K. Computational studies of Sb?Sb bond energies, barriers of pyramidal inversion at Sb, and the conformati...

Synthesis of Antimony Doped Amorphous Carbon Films

Science.gov (United States)

Okuyama, H.; Takashima, M.; Akasaka, H.; Ohtake, N.

2013-06-01

We report the effects of antimony (Sb) doping on the electrical and optical properties of amorphous carbon (a-C:H) films grown on silicon and copper substrates by magnetron sputtering deposition. For film deposition, the mixture targets fabricated from carbon and antimony powders was used. The atomic concentration of carbon, hydrogen, and antimony, in the film deposited from the 1.0 mol% Sb containing target were 81, 17, 2 at.%, respectively. These elements were homogeneously distributed in the film. On the structural effect, the average continuous sp2 carbon bonding networks decreased with Sb concentration increasing, and defects in the films were increased with the Sb incorporation because atomic radius of Sb atoms is twice larger size than that of carbon. The optical gap and the electrical resistivity were carried out before and after the Sb doping. The results show that optical gap dropped from 3.15 to 3.04 eV corresponding to non-doping to Sb-doping conditions, respectively. The electrical resistivity reduced from 10.5 to 1.0 MΩm by the Sb doping. These results suggest the doping level was newly formed in the forbidden band.

Synthesis of Antimony Doped Amorphous Carbon Films

International Nuclear Information System (INIS)

Okuyama, H; Takashima, M; Akasaka, H; Ohtake, N

2013-01-01

We report the effects of antimony (Sb) doping on the electrical and optical properties of amorphous carbon (a-C:H) films grown on silicon and copper substrates by magnetron sputtering deposition. For film deposition, the mixture targets fabricated from carbon and antimony powders was used. The atomic concentration of carbon, hydrogen, and antimony, in the film deposited from the 1.0 mol% Sb containing target were 81, 17, 2 at.%, respectively. These elements were homogeneously distributed in the film. On the structural effect, the average continuous sp 2 carbon bonding networks decreased with Sb concentration increasing, and defects in the films were increased with the Sb incorporation because atomic radius of Sb atoms is twice larger size than that of carbon. The optical gap and the electrical resistivity were carried out before and after the Sb doping. The results show that optical gap dropped from 3.15 to 3.04 eV corresponding to non-doping to Sb-doping conditions, respectively. The electrical resistivity reduced from 10.5 to 1.0 MΩm by the Sb doping. These results suggest the doping level was newly formed in the forbidden band.

Electrodeposition of antimony, tellurium and their alloys from molten acetamide mixtures

NARCIS (Netherlands)

Nguyen, H.P.; Peng, X.; Murugan, G.; Vullers, R.J.M.; Vereecken, P.M.; Fransaer, J.

2013-01-01

We examine the electrodeposition of antimony (Sb), tellurium (Te) and their alloys from molten mixtures of acetamide - antimony chloride and tellurium chloride. The binary mixtures of acetamide with SbCl3 and TeCl 4 exhibit eutectic formation with large depressions of freezing points to below room

40 CFR 421.140 - Applicability: Description of the primary antimony subcategory.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability: Description of the primary antimony subcategory. 421.140 Section 421.140 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Antimony Subcategory § 421.140...

Antimony recycling in the United States in 2000

Science.gov (United States)

Carlin, James F.

2006-01-01

The importance of recycling has become more obvious as concerns about the environment and import dependence have grown in recent years. When materials are recycled, fewer natural resources are consumed, and less waste products go to landfills or pollute the water and air. This study, one of a series of reports on metals recycling in 2000, discusses the flow of antimony from mining through its uses and disposal with emphasis on recycling. In 2000, the recycling efficiency for antimony was estimated to be 89 percent, and the recycling rate was about 20 percent.

40 CFR 440.90 - Applicability; description of the antimony ore subcategory.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Applicability; description of the antimony ore subcategory. 440.90 Section 440.90 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Antimony Ore Subcategory § 440.90 Applicability;...

Surface area of antimony oxide by isotope exchange and other methods

Energy Technology Data Exchange (ETDEWEB)

Rao, Y.K.; Acharya, B.V.; Rangamannar, B.

1985-06-17

Specific surface areas of antimony oxide samples, one commercial, the other prepared from antimony trichloride were measured by heterogeneous isotope exchange, gas adsorption, air permeability and microscopic methods. Specific surface areas obtained by these four methods for the two samples were compared and the observed differences are explained.

Selective oxidation of propene on bismuth molybdate and mixed oxides of tin and antimony and of uranium and antimony

International Nuclear Information System (INIS)

Pendleton, P.; Taylor, D.

1976-01-01

Propene + 18 0 2 reactions have been studied in a static reaction system on bismuth molybdate and mixed oxides of tin and antimony and of uranium and antimony. The [ 16 0] acrolein content of the total acrolein formed and the proportion of 16 0 in the oxygen of the carbon dioxide by-product have been determined. The results indicate that for each catalyst the lattice is the only direct source of the oxygen in the aldehyde, and that lattice and/or gas phase oxygen is used in carbon dioxide formation. Oxygen anion mobility appears to be greater in the molybdate catalyst than in the other two. (author)

Copper-promoted cementation of antimony in hydrochloric acid system: A green protocol

Energy Technology Data Exchange (ETDEWEB)

Wu, Lian-Kui; Li, Ying-Ying; Cao, Hua-Zhen; Zheng, Guo-Qu, E-mail: zhenggq@zjut.edu.cn

2015-12-15

Highlights: • Antimony can be efficiently removed by cementation with copper powder. • Cemented antimony is in the form of Cu{sub 2}Sb. • Consumed copper powder is transformed to CuCl. • The cementation is a chemically controlled step. • No toxic stibine generates during the cementation process. - Abstract: A new method of recovering antimony in hydrochloric acid system by cementation with copper powder was proposed and carried out at laboratory scale. Thermodynamic analysis and cyclic voltammetry test were conducted to study the cementation process. This is a novel antimony removal technology and quite meets the requirements of green chemistry. The main cement product Cu{sub 2}Sb is a promising anodic material for lithium and sodium ion battery. And nearly all consumed copper powder are transformed into CuCl which is an important industrial material. The effect of reaction temperature, stoichiometric ratio of Cu to Sb(III), stirring rate and concentration of HCl on the cementation efficiency of antimony were investigated in detail. Optimized cementation condition is obtained at 60 °C for 120 min and stirring rate of 600 rpm with Cu/Sb(III) stoichiometric ratio of 6 in 3 mol L{sup −1} HCl. At this time, nearly all antimony can be removed by copper powder and the cementation efficiency is over 99%. The structure and morphologies of the cement products were characterized by X-ray diffraction and scanning electron microscopy, respectively. Results show that the reaction temperature has little influence on the morphology of the cement products which consist of particles with various sizes. The activation energy of the cementation antimony on copper is 37.75 kJ mol{sup −1}, indicating a chemically controlled step. Inductively coupled plasma mass spectrometry results show that no stibine generates during the cementation process.

Investigation of Antimony Leaching from Bottles (PET into the Bottled Waters in Fars Province

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Masoud Noshadi

2015-05-01

Full Text Available Polyethylene Terephthalate (PET is the most common material used in manufacturing mineral water bottles. Antimony trioxide (Sb2O3 used to form the PET containers may pollute water with their ingredients. In this research, graphite furnance atomic absorption spectrometry was used to investigate the effects of storage time (1 to 8 weeks, storage temperature (-20 to 80 °C, pH (6.3 to 8.3, exposure to sunlight, and UV radiation on leaching antimony from PET bottles into the mineral water of 15 bottled water brands available in Fars Province. Concentrations of antimony in the first and second weeks were lower than the maximum standard limit (5 ppb recommended by Iranian regulations. Antimony concentration in one sample (brand A rose above the standard limit after four weeks and in 3 samples (brands A, F, and J with antimony concentrations of 5.48, 5.08, and 5.06 µg/L, respectively exceeded the standard limit after 8 weeks. Sunlight, UV radiation, changes in pH, and storage at temperatures of -20 ℃, 60 ℃, and 80℃ were also found to increase antimony concentrations to levels above the maximum standard limit. Clearly, storing bottled mineral water in ambient conditions may lead to the release of antimony into bottled water, which is a serious threat to public health.

Montmorillonite Supported Titanium/Antimony Catalyst:Preparation, Characterization and Immobilization

Institute of Scientific and Technical Information of China (English)

CHEN Guiyong; WANG Xiaoqun; ZHAO Chuan; DU Shanyi

2014-01-01

Montmorillonite supported titanium (Ti-MMT) or antimony catalyst (Sb-MMT) has been a hot area of research on preparing polyethylene terephthalate/montmorillonite (PET/MMT) nanocomposites by in situ polymerization. So removal of Ti or Sb from Ti-MMT or Sb-MMT is not expected during in situ polymerization. Studies on immobilization of Ti or Sb on Ti-MMT or Sb-MMT are seldom reported. In this work, a series of montmorillonite supported catalysts of titanium (Ti-MMT) or antimony (Sb-MMT) and co-intercalated montmorillonite of titanium and antimony (Ti/Sb-MMT) were prepared by (1) the reaction of sodium bentonite suspension with intercalating solution containing titanium tetrachloride and/or antimony chloride, and (2) drying or calcinating the products at different temperature (100, 150, 240, 350 and 450℃). The physicochemical properties of these MMT supported catalysts were studied by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma optical emission spectrometer (ICPOES), N2 adsorption/desorption isotherms, UV-visible diffuse reflectance spectroscopy(UV-vis) and transmission electron microscopy (TEM). The immobile character of Ti or Sb on MMT supported catalysts was evaluated by a two-step method in deionized water or ethylene glycol. Several results were obtained, i e, (a) during the preparation, with an increase in drying or calcinating temperature, the amount of titanium and/or antimony species remained on these MMT supported catalysts decreased, (b) the experiments about immobile character of Ti or/and Sb showed that with an increase in drying or calcinating temperature, the immobilization of Ti and/or Sb species remained on these MMT supported catalysts increased gradually, (c) Ti-MMT calcinated at 450℃had the biggest pore volume, which means Ti-MMT had the best adsorption application prospect.

Antimony-121 Moessbauer spectra of antimony(III) compounds with a stereochemically active lone pair

International Nuclear Information System (INIS)

Takeda, Masuo; Takahashi, Masashi; Ohyama, Ryuhichi

1986-01-01

The Sb-121 Moessbauer parameters at 20 K for 23 antimony(III) compounds were obtained and the data are discussed in terms of known crystal structures. The isomer shifts and quadrupole coupling constants depend strongly on the type of configuration around the Sb(III) atoms with stereochemically active lone pair electrons. (Auth.)

Vapor transport deposition of antimony selenide thin film solar cells with 7.6% efficiency.

Science.gov (United States)

Wen, Xixing; Chen, Chao; Lu, Shuaicheng; Li, Kanghua; Kondrotas, Rokas; Zhao, Yang; Chen, Wenhao; Gao, Liang; Wang, Chong; Zhang, Jun; Niu, Guangda; Tang, Jiang

2018-06-05

Antimony selenide is an emerging promising thin film photovoltaic material thanks to its binary composition, suitable bandgap, high absorption coefficient, inert grain boundaries and earth-abundant constituents. However, current devices produced from rapid thermal evaporation strategy suffer from low-quality film and unsatisfactory performance. Herein, we develop a vapor transport deposition technique to fabricate antimony selenide films, a technique that enables continuous and low-cost manufacturing of cadmium telluride solar cells. We improve the crystallinity of antimony selenide films and then successfully produce superstrate cadmium sulfide/antimony selenide solar cells with a certified power conversion efficiency of 7.6%, a net 2% improvement over previous 5.6% record of the same device configuration. We analyze the deep defects in antimony selenide solar cells, and find that the density of the dominant deep defects is reduced by one order of magnitude using vapor transport deposition process.

Synthesis of barium mercaptides and application of antimony/barium mercaptides

Institute of Scientific and Technical Information of China (English)

瞿龙; 张露露; 舒万艮

2001-01-01

Mercaptoacetic acid, isooctyl thioglycolate and barium hydroxide used as start materials, barium bis (2-ethylhexyl thioglycolate) (Ba(2EHTG)2), barium thioglycolate (Ba(TG)) and barium bisthioglycolate (Ba(TG)2) were synthesized. Their optimum synthetic techniques were discussed, and some physicochemical data were reported. Infrared spectroscopy and elemental analysis methods were used to identify the structures. They were put into PVC plastic products together with antimony tris (2-ethylhexyl thioglycolate) (Sb(2EHTG)3) under the suitable compounding, and their heat stability to PVC was studied. It is shown that these barium mercaptides have remarkable synergisms with antimony mercaptides and the long-term stabilizing effect of organoantimony stabilizer can be effectively improved, reducing the amount of antimony compounds so as to avoid the decrease of its stabilizing effect.

Antimony sorption properties of chitosan - nano TiO2 composite beads

International Nuclear Information System (INIS)

Nishad, Padala Abdul; Bhaskarapillai, Anupkumar; Velmurugan, Sankaralingam

2015-01-01

Routine decontamination campaigns of nuclear reactors are generally effective in removing various radionuclides such as cobalt, caesium, etc., and bring down the radiation field. However, during some of the decontamination campaigns, the radiation field at some surfaces was seen to have actually gone up. This was found to be due to lack of removal of antimony isotopes by the regular ion exchange resins used, which subsequently deposited over out of core surfaces leading to increased radiation field on those surfaces. Thus there exists a need for efficient antimony removal system. We have synthesised nano titania impregnated - epichlorohydrin crosslinked chitosan beads, which were found to have high sorption capacity for antimony. The beads, which were synthesised in formats suitable for large scale (column mode) applications, were shown to be effective sorbent of antimony in both +3 and +5 oxidation states. The sorbent exhibited complete removal of antimony from its aqueous solutions of concentration ranging from 150 ppb to 120 ppm. In order to understand the sorption mechanism and to fine tune the bead composition, the effect of crosslinker concentration used during the synthesis on the swelling and sorption properties of the beads was investigated in detail. The variation effected significant changes in physical parameters such as bead diameter, swelling ratio, equilibrium water content and true wet density. Sorption capacity, unlike with regular resins, was found to increase with increase in crosslinker amount. The antimony sorption capacity of the crosslinked beads prepared by crosslinking 0.3 g uncrosslinked beads with 6.4 mmol epichlorohydrin (crosslinker) was 493 μmol/g. Non-crosslinked beads showed a capacity of 75 μmol/g, while the crosslinked beads made with the least amount of crosslinker (0.64 mmol per 0.3 g beads) showed a capacity of 133 μmol/g. These results indicate the possible involvement of the crosslinker in the sorption. (author)

Radiochemical studies of the separation of some chloro-complexes of tin, antimony, cadmium and indium

International Nuclear Information System (INIS)

Ramamoorthy, N.; Mani, R.S.

1976-01-01

Radioisotopes of tin, antimony, cadmium and indium such as tin-113, antimony-124, antimony-125, cadmium-109, cadmium-115, indium-113m and indium-111 find extensive applications as tracers in various fields. These isotopes are produced by irradiation of targets in a reactor or a cyclotron. It is usually observed that in addition to the nuclear reactions giving rise to the desired isotopes, side reactions also take place giving rise to radionuclidic contaminants. Thus, antimony-125, indium-114m and indium-114 will be present in the cyclotron produced indium-111. The authors have studied column chromatography over hydrous zirconia for the separation of antimony from tin and indium, and cadmium from indium. These studies have thrown light on the role and behaviour of antimony-125 present as an impurity in tin-113 during the preparation of tin-113-indium-113m generators and have indicated methods for the preparation of 115 Cd-sup(115m)In generators and for separation of 111 In from proton irradiated cadmium targets. (Authors)

Synthesis and tribological properties of antimony N, N-diethanoldithiocarbamate

Institute of Scientific and Technical Information of China (English)

李丽; 黄可龙; 瞿龙; 舒万艮

2001-01-01

Antimony N, N-diethanoldithiocarbamate was synthesized with diethanolamine, antimony trioxide and carbon disulfide. The influences of temperature, reaction time, solvents and their dosages were investigated, and the optimum synthesis conditions were: reaction temperature 15～20 ℃, reaction time 2.5 h, 250 mL CH3OH as solvent and the hot CH3OH as recrystallization solvent. Element analysis, IR, 1HNMR and 13CNMR spectra were used to study its chemical composition and molecular structure. Antimony N, N-diethanol-dithiocarbamate was added in the base oil, and its properties of wear resistance and extreme pressure were studied by FB, FD and WSD. The synthesis product behaves per fectly as wear resistance and extreme pressure additive and its extreme pressure property is superior to its wear resistance property. The mechanism of tribological action was discussed by using XPS and AES spectra, and the reason of good wear resistance and extreme pressure properties is that the synthesis product decompose element C, S and N.

New fluorescent polymeric nanocomposites synthesized by antimony dodecyl-mercaptide thermolysis in polymer

Directory of Open Access Journals (Sweden)

2009-04-01

Full Text Available In this work, the formation of semiconductive Sb2S3 nanoparticles inside amorphous polystyrene has been achieved by thermal degradation of the corresponding antimony dodecyl-mercaptide, Sb(SC12H253. The thermolysis of the dodecyl-mercaptide precursor was studied as both pure phase and mercaptide solution in polystyrene. The thermal decomposition of the antimony mercaptide precursor at 350°C, under vacuum, showed the formation of a mixture of antimony trisulfide (stibnite, Sb2S3 and zero-valent antimony (Sb phase. X-ray Powder Diffraction (XRD and Rietveld analysis carried out on the obtained nanostructured powder confirmed the presence of Sb and Sb2S3 phases in 10.4 wt% and 89.6 wt% amount, respectively. The same pyrolysis reaction was carried out in the polymer and the resulting nanocomposite material was characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, UV-VIS spectroscopy, and fluorescence spectroscopy. The nanocomposite structural characterization indicated the presence of well-dispersed nanoclusters of antimony and stibnite (15–30 nm in size inside the amorphous polymeric phase. Optical measurements on the obtained nanocomposite films showed a strong emission at 432 nm upon excitation at 371 nm, probably related to the presence of Sb2S3 nanoclusters.

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 ...

Removal of lead from crude antimony by using NaPo3 as lead elimination reagent

Directory of Open Access Journals (Sweden)

Ye L.G.

2015-01-01

Full Text Available In order to solve the shortcomings when removing lead from crude antimony in the traditional antimony smelting, a new process was provided using NaPO3 as lead elimination reagent to yield phosphate slag, and it was removed by floating on the surface of the liquid antimony. Reaction mechanism was clarified by using the TG-DTA and XRD techniques and single factor experiments of removal lead from crude antimony were engaged. The results show that PbO and NaPO3 begin endothermic reaction at 863K (590°C, and the reaction mainly form NaPb4(PO43 and NaPbPO4 below 1123K (850°C and above 1123K (850°C, respectively. Sb2O3 and NaPO3 start the reaction at 773K (500°C and generate an antimonic salt compound. The reaction product of the mixture of PbO, Sb2O3 and NaPO3 show that NaPO3 reacted with PbO prior when NaPO3 was insufficient, amorphous antimony glass will be generated only when NaPO3 was adequate. Single factor experiments were taken with NaNO3 as oxidizing agent under argon, effect of reaction time, reaction temperature and dosage of NaPO3 and NaNO3 on smelting results. The average content of lead in refined antimony was 0.05340% and 98.85% of lead were removed under optimal conditions; the content of lead in antimony have meet the requirements of commercial antimony.

Patrick Air Force Base Storm Water Pollution Prevention Plan.

Science.gov (United States)

1994-09-01

7758987 Cupric sulfate 77-47-4 Hexachlorocyclopentadliene 10380297 Cupric sulfate, ammoniated 67-72-1 H-exachloroethane 815827 Cupric tartrate 76-47-01...28300745 Antimony potassium 75-00-3 Chloroethane (Ethyl chlo- tartrate ride) 7789619 Antimony tribromide 67-66-3 Chloroform 10025919 Antimony...5 p-Cresol 7787475 Beryllium chloride 1319-77-3 Cresol (mixed isomers) 7787497 Beryllium fluoride 142712 Cupric acetate 7787555 Beryllium nitrate

Neutron activation analysis of arsenic and antimony in human hair

International Nuclear Information System (INIS)

Kanda, Yukio; Isono, Hideo; Kozuka, Hiroshi.

1975-01-01

A radiochemical neutron activation method for the determination of trace amounts of arsenic and antimony in human hair samples is studied. The sample of hair (100 mg) irradiated for 5 hours with a neutron flux of 2.1x10 12 n/cm 2 s was decomposed with a sulfuric-nitric acid mixture after addition of each 5 mg of arsenic and antimony as carrier. Arsine and stibine were evolved from the solution of decomposed hair by reduction with 3 g of granular zinc and were absorbed in 0.1N iodine solution for half an hour. Metal arsenic was separated from iodine solution by precipitation with sodium hypophosphite, followed by precipitation of antimony as sulfide with thioacetamide. These precipitates were dissolved and their gamma-ray spectra were measured with a well type 3''x3'' NaI(TI) detector equipped with a 200 channel pulse-height analyzer. After the measurement of gamma-ray spectra, the chemical yields were determined by colorimetric methods. The relative standard deviations were 7% and 4% for 0.01 μg As and 0.024 μg Sb, respectively. The sensitivity of this method was estimated to be 1x10 -3 μg for arsenic and 2x10 -3 μg for antimony. (auth.)

The acidic properties of mixed tin and antimony oxide catalysts

Energy Technology Data Exchange (ETDEWEB)

Irving, E.A.; Taylor, D.

1978-01-01

The acidic properties of mixed tin + antimony oxide catalysts were studied in the isomerization of 3,3-dimethyl-1-butene, cyclopropane, 1-butene, and cis-2-butene and the dehydration of isopropanol over the mixed oxides outgassed at room temperature and 698/sup 0/K. Only the zero-order portions of the reaction were used for calculations. With catalysts outgassed at room temperature, weakly acidic sites were present, and all the reactions probably occurred by a carbonium ion mechanism with Broensted acid sites as a source of protons. The rates increased with increasing antimony content to a maximum at approx. 50 at. % and then decreased with further increase in the antimony content. Outgassing of the catalysts at 698/sup 0/K increased the isomerization rate of 3,3-dimethyl-1-butene, but decreased those for cyclopropane and isopropanol due to poisoning by the propylene produced. For 1-butene and cis-2-butene and catalysts outgassed at 698/sup 0/K, only catalysts with less than 50Vertical Bar3< antimony were active. The catalysts were poisoned by treatment with bases or with sodium acetate. A proposed correlation between rates and acidity led to the conclusion that the catalyst composition corresponding to maximum acidity differs from that for maximum selective oxidation activity. Graphs and 10 references.

In Vitro antileishmanial properties of neutron-irradiated meglumine antimoniate

Directory of Open Access Journals (Sweden)

Samanta Etel Treiger Borborema

2005-10-01

Full Text Available Pentavalent antimony, as meglumine antimoniate (Glucantime® or sodium stibogluconate (Pentostam® , is the main treatment for leishmaniasis, a complex of diseases caused by the protozoan Leishmania, and an endemic and neglected threat in Brazil. Despite over half a century of clinical use, their mechanism of action, toxicity and pharmacokinetic data remain unknown. The analytical methods for determination of antimony in biological systems remain complex and have low sensitivity. Radiotracer studies have a potential in pharmaceutical development. The aim of this study was to obtain a radiotracer for antimony, with suitable physical and biological properties. Meglumine antimoniate was neutron irradiated inside the IEA-R1 nuclear reactor, producing two radioisotopes 122Sb and 124Sb, with high radionuclidic purity and good specific activity. This compound showed the same antileishmanial activity as the native compound. The use of the radiotracers, easily created by neutron irradiation, could be an interesting tool to solve important questions in antimonial pharmacology.Os antimoniais pentavalentes, como o antimoniato de meglumina (Glucantime® ou estibogluconato de sódio (Pentostam® , são o principal tratamento para a leishmaniose, um complexo de doenças causadas pelo protozoário parasita Leishmania, uma doença endêmica e negligenciada no Brasil. Apesar do seu uso clínico por mais de meio século, seu mecanismo de ação, toxicidade e dados de farmacocinética permanecem desconhecidos. Os métodos analíticos para determinação de antimônio em sistemas biológicos são complexos e apresentam baixa sensibilidade. Estudos utilizando radiotraçadores têm papel potencial no desenvolvimento farmacológico. O objetivo deste estudo foi desenvolver um radiotraçador de antimônio, com propriedades físicas e biológicas adequadas. O antimoniato de meglumina foi irradiado por nêutrons no reator nuclear IEA-R1, produzindo dois radioisótopos: 122

Arsenic and antimony removal from drinking water by adsorption on granular ferric oxide.

Science.gov (United States)

Sazakli, Eleni; Zouvelou, Stavroula V; Kalavrouziotis, Ioannis; Leotsinidis, Michalis

2015-01-01

Arsenic and antimony occur in drinking water due to natural weathering or anthropogenic activities. There has been growing concern about their impact on health. The aim of this study was to assess the efficiency of a granular ferric oxide adsorbent medium to remove arsenic and antimony from drinking water via rapid small-scale column tests (RSSCTs). Three different water matrices - deionized, raw water treated with a reverse osmosis domestic device and raw water - were spiked with arsenic and/or antimony to a concentration of 100 μg L⁻¹. Both elements were successfully adsorbed onto the medium. The loadings until the guideline value was exceeded in the effluent were found to be 0.35-1.63 mg g⁻¹ for arsenic and 0.12-2.11 mg g⁻¹ for antimony, depending on the water matrix. Adsorption of one element was not substantially affected by the presence of the other. Aeration did not affect significantly the adsorption capacity. Granular ferric oxide could be employed for the simultaneous removal of arsenic and antimony from drinking water, whereas full-scale systems should be assessed via laboratory tests before their implementation.

Standardization of intralesional meglumine antimoniate treatment for cutaneous leishmaniasis.

Science.gov (United States)

Duque, Maria Cristina de Oliveira; Vasconcellos, Érica de Camargo Ferreira E; Pimentel, Maria Inês Fernandes; Lyra, Marcelo Rosandiski; Pacheco, Sandro Javier Bedoya; Marzochi, Mauro Celio de Almeida; Rosalino, Cláudia Maria Valete; Schubach, Armando de Oliveira

2016-01-01

Intralesional treatment for cutaneous leishmaniasis has been applied for over 30 years at the Oswaldo Cruz Foundation, Rio de Janeiro, with good therapeutic results and without relevant systemic toxicity. Meglumine antimoniate was injected subcutaneously, using a long medium-caliber needle (for example, 30mm × 0.8mm); patients received 1-3 injections, with 15-day intervals. The technique is described in detail sufficient to enable replication. The treatment of cutaneous leishmaniasis with intralesional meglumine antimoniate is a simple, effective, and safe technique, which may be used in basic healthcare settings.

Preparation and characterization of antimony barium composite oxide photocatalysts

Science.gov (United States)

Han, X. P.; Yao, B. H.; Pan, Q. H.; Pen, C.; Zhang, C. L.

2018-01-01

In this paper, two kinds of antimony barium composite oxide photocatalysts have been prepared by two methods and characterized by XRD and SEM. The photocatalytic activity was evaluated by a photocatalytic reactor and an ultraviolet spectrophotometer. The results showed that-BaSb2O5•4H2O, BaSb2O6 two kinds of antimony barium composite oxide photocatalysts were successfully prepared in this experiment and they showed good photocatalytic properties. In addition, BaSb2O6 morphology showed more regular, microstructure and better catalytic performance.

Pilot plant studies on the extraction of antimony metal from lower grade krinj stibnite ore

International Nuclear Information System (INIS)

Rehman, W.; Riaz, M.; Ishaq, M.

2013-01-01

Antimony is a silvery white, brittle and crystalline solid which is extensively consumed in lead acid batteries, antimonial lead alloys, flame retardants and a variety of metallic products. The antimony content of commercial ores range from 5-60% and determines the method of extraction, either pyrometallurgical or hydrometallurgical. The present study focuses on pilot plant scale extraction of antimony metal from lower grade stibnite ore of Krinj (Chitral) without the use of iron scrap, thus eliminating the second step of iron removal in conventional direct reduction method. A tilting gas fired furnace with digital temperature control system and a heat recuperator was designed to optimize the operating parameters for extraction of antimony metal. Weight ratios of flux and reductant, operating time and operating temperature were optimized. Highest percentage recovery and purity were achieved using soda ash as a flux, at a temperature of 900 degree C for 2 hours. (author)

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 ...

Leishmania donovani: an in vitro study of antimony-resistant amphotericin B-sensitive isolates

DEFF Research Database (Denmark)

Sharief, Abdalla Hassan; Gasim Khalil, Eltahir Awad; Theander, Thor G

2006-01-01

Drug sensitivity of clinically antimony-unresponsive Leishmania donovani isolates from Eastern Sudan was evaluated in an in vitro culture system against sodium stibogluconate (Pentostam) and Amphotericin B. Eight isolates, six from antimony-resistant and two from clinically responsive patients were...

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.

Antimony and arsenic exhibit contrasting spatial distributions in the sediment and vegetation of a contaminated wetland.

Science.gov (United States)

Warnken, Jan; Ohlsson, Rohana; Welsh, David T; Teasdale, Peter R; Chelsky, Ariella; Bennett, William W

2017-08-01

Antimony is a priority environmental contaminant that is relatively poorly studied compared to other trace metal(loid)s. In particular, the behaviour of antimony in wetland sediments, where anaerobic conditions often dominate, has received considerably less attention compared to well-drained terrestrial soil environments. Here we report the results of a spatial assessment of antimony in the sediments and vegetation of a freshwater wetland exposed to stibnite tailings for the past forty years. The concentration of antimony in the sediment decreased rapidly with distance from the tailings deposit, from a maximum of ∼22,000 mg kg -1 to ∼1000 mg kg -1 at a distance of ∼150 m. In contrast, arsenic was distributed more evenly across the wetland, indicating that it was more mobile under the prevailing hypoxic/anoxic conditions. Less clear trends were observed in the tissues of wetland plants, with the concentrations of antimony in waterlilies (2.5-195 mg kg -1 ) showing no clear trends with distance from the tailings deposit, and no correlation with sediment concentrations. Sedges and Melaleuca sp. trees had lower antimony concentrations (<25 mg kg -1 and 5 mg kg -1 , respectively) compared to waterlilies, but showed a non-significant trend of higher concentrations closer to the tailings. For all vegetation types sampled, antimony concentrations were consistently lower than arsenic concentrations (Sb:As = 0.27-0.31), despite higher concentrations of antimony in the sediment. Overall, the results of this study highlight clear differences in the behaviour of antimony and arsenic in freshwater wetlands, which should be considered during the management and remediation of such sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effects of antimony doping on the surface structure of rutile TiO2(110)

International Nuclear Information System (INIS)

Bechstein, Ralf; Schuette, Jens; Kuehnle, Angelika; Kitta, Mitsunori; Onishi, Hiroshi

2009-01-01

Titanium dioxide represents a very important wide bandgap photocatalyst that is known to be sensitized to visible light by transition metal doping. Antimony doping has been demonstrated to provide photocatalytic activity when codoped with chromium at an optimum dopant ratio [Sb]/[Cr] of about 1.5. Here, the role of antimony doping on the surface structure of rutile TiO 2 (110) is studied using non-contact atomic force microscopy (NC-AFM) under ultra-high vacuum conditions. At first glance, the surface structure of antimony-doped TiO 2 (110) resembles the structure of pristine TiO 2 (110). However, in contrast to what is found in pristine TiO 2 (110), a dense layer of protruding features is observed upon antimony doping, which is tentatively ascribed to antimony-rich clusters. Moreover, homogeneously distributed holes are found on the surface, which differ in depth and shape depending on the preparation conditions. Holes with depths ranging from a few up to more than a hundred monatomic steps are observed. These holes are explained by surface segregation of antimony during annealing, as the ionic radius of Sb 3+ is considerably larger than the ionic radius of Ti 4+ . Our finding provides an indication of why an antimony concentration larger than the optimum ratio results in decreased photocatalytic activity. Moreover, controlling annealing temperature seems to constitute a promising strategy for creating nanosized holes on TiO 2 surfaces.

Exposure to antimony from polyethylene terephthalate (PET) trays used in ready-to-eat meals.

Science.gov (United States)

Haldimann, M; Blanc, A; Dudler, V

2007-08-01

Antimony residues, a result of the use of a polycondensation catalyst in the production of polyethylene terephthalate (PET) oven-proof trays, were analysed in ready-to-eat meals. The toxicity of antimony has raised concerns about consumer safety; therefore, the migration of small fractions of these residues into ready meals and foods as a result of cooking directly in the PET trays was studied. A straightforward approach of measuring real samples was selected to obtain accurate exposure data. Background antimony concentration was determined separately from a series of lunch meals, which ranged from not detectable to 3.4 microg kg(-1). Microwave and conventional oven-cooking caused a distinct increase in the concentration of antimony in food and ready meals of 0-17 and 8-38 microg kg(-1), respectively, depending, to a certain extent, on the industrial preparations. The migrated quantities of antimony corresponded to 3-13 microg. For comparison, PET roasting bags and ready-made dough products in PET baking dishes were also evaluated. About half of the products prepared at a temperature of 180 degrees C exceeded the specific migration limit set for food contact material by the European Commission. However, the migrated amounts of antimony relative to the accepted tolerable daily intake (TDI) show that exposure from this type of food is currently not of toxicological concern.

Effect of antimony nano-scale surface-structures on a GaSb/AlAsSb distributed Bragg reflector

International Nuclear Information System (INIS)

Husaini, S.; Shima, D.; Ahirwar, P.; Rotter, T. J.; Hains, C. P.; Dang, T.; Bedford, R. G.; Balakrishnan, G.

2013-01-01

Effects of antimony crystallization on the surface of GaSb during low temperature molecular beam epitaxy growth are investigated. The geometry of these structures is studied via transmission electron and atomic force microscopies, which show the surface metal forms triangular-shaped, elongated nano-wires with a structured orientation composed entirely of crystalline antimony. By depositing antimony on a GaSb/AlAsSb distributed Bragg reflector, the field is localized within the antimony layer. Polarization dependent transmission measurements are carried out on these nano-structures deposited on a GaSb/AlAsSb distributed Bragg reflector. It is shown that the antimony-based structures at the surface favor transmission of light polarized perpendicular to the wires.

Adsorption of antimony onto iron oxyhydroxides: Adsorption behavior and surface structure

Energy Technology Data Exchange (ETDEWEB)

Guo, Xuejun; Wu, Zhijun [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875 (China); He, Mengchang, E-mail: hemc@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875 (China); Meng, Xiaoguang [Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Jin, Xin [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875 (China); Qiu, Nan; Zhang, Jing [Beijing Synchrotron Radiation Facility (BSRF), Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2014-07-15

Graphical abstract: - Highlights: • Antimony adsorption depended on the Sb species, pH, and the type of iron oxides. • Sb(V) adsorption favored at acidic pH, Sb(III) adsorption optimized in wider pH. • Antimony was adsorbed onto the iron oxides by the inner-sphere surface complex. • Bidentate mononuclear ({sup 2}E) was the dominant form of Sb incorporated into HFO. • XAFS and XPS indicated Sb(III) adsorbed was slowly oxidized to Sb(V). - Abstract: Antimony is detected in soil and water with elevated concentration due to a variety of industrial applications and mining activities. Though antimony is classified as a pollutant of priority interest by the United States Environmental Protection Agency (USEPA) and Europe Union (EU), very little is known about its environmental behavior and adsorption mechanism. In this study, the adsorption behaviors and surface structure of antimony (III/V) on iron oxides were investigated using batch adsorption techniques, surface complexation modeling (SCM), X-ray photon spectroscopy (XPS) and extended X-ray absorption fine structure spectroscopy (EXAFS). The adsorption isotherms and edges indicated that the affinity of Sb(V) and Sb(III) toward the iron oxides depended on the Sb species, solution pH, and the characteristics of iron oxides. Sb(V) adsorption was favored at acidic pH and decreased dramatically with increasing pH, while Sb(III) adsorption was constant over a broad pH range. When pH is higher than 7, Sb(III) adsorption by goethite and hydrous ferric oxide (HFO) was greater than Sb(V). EXAFS analysis indicated that the majority of Sb(III), either adsorbed onto HFO or co-precipitated by FeCl{sub 3}, was oxidized into Sb(V) probably due to the involvement of O{sub 2} in the long duration of sample preservation. Only one Sb–Fe subshell was filtered in the EXAFS spectra of antimony adsorption onto HFO, with the coordination number of 1.0–1.9 attributed to bidentate mononuclear edge-sharing ({sup 2}E) between Sb and

Redox speciation analysis of antimony in soil extracts by hydride generation atomic fluorescence spectrometry

International Nuclear Information System (INIS)

Fuentes, Edwar; Pinochet, Hugo; Gregori, Ida de; Potin-Gautier, Martine

2003-01-01

A sensitive atomic spectrometric method for the redox speciation analysis of antimony in soils is described. The method is based on the selective generation of stibine from Sb(III) in a continuous flow system using atomic fluorescence spectrometry for detection. Sb(V) is masked by citric or oxalic acid in HCl medium. The procedure was optimized with synthetic solutions of Sb(III) and Sb(V). The effect of carboxylic acid and HCl concentration on the recovery of Sb(III) and Sb(V) species from standard solutions, and on the fluorescence signal were studied. Both species were extracted from soil with H 2 O, 0.05 mol l -1 EDTA and 0.25 mol l -1 H 2 SO 4 . Since the soil samples were collected from sites impacted by copper mining activities, the effect of Cu 2+ on the determination of antimony in synthetic solutions and soil extracts was studied. Cu 2+ decreased the Sb(III) signal, but had no effect on the total antimony determination. Therefore, the selective determination of Sb(III) was carried out in citric acid-HCl medium, using the analyte addition technique. Total antimony in soil extracts was determined using the standard calibration technique after reducing Sb(V) to Sb(III) at room temperature with KI-ascorbic acid. The Sb(V) concentration was calculated from the difference between total antimony and Sb(III). The limits of detection (PS Analytical, Excalibur Millennium model) were 17 and 10 ng l -1 for Sb(III) and total antimony, respectively, and the R.S.D. at the 0.5-μg l -1 level were 2.5 and 2.4%, respectively. The total antimony concentration of soils is in the mg kg -1 range; the Sb recovery from the different soils by the extracting solutions was between less than 0.02% and approximately 10%. Similar recoveries were obtained using EDTA and sulfuric acid solutions. Sb(V) was found to be the main antimony species extracted from soils

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...

Possibilities of using neutron activation analysis to discovery antimony aureoles at near-surface deposits

International Nuclear Information System (INIS)

Voin, M.I.; Kuligin, V.M.; Rakovskij, Eh.E.

1978-01-01

Described is the technique for determining antimony in rock and ore samples by instrumental neutron activation method with the sensitivity of 0.5 g/t from the 0.3-0.5 g weighed amount. Antimony was determined using the photopeak of antimony-124 isotope with the energy of 1692 keV. For analysis, 0.1 g samples were packed in aluminium foil and irradiated for 22 hours by reactor neutron fluence of 1.2x10 13 neutron/cm 2 xs. After cooling for 7 days induced activity of samples was measured using multichannel analizer with semiconductor detector with sensitive zone volume of 40 cm 3 . Real sensitivity while determining antimony was 1g/t, mean square error in the content range of 1-10 g/t is 14%

Antimony production by carbothermic reduction of stibnite in the presence of lime

Directory of Open Access Journals (Sweden)

Padilla R.

2014-01-01

Full Text Available Experimental work on the carbothermic reduction of Sb2S3 in the presence of lime was carried out in the temperature range of 973 to 1123 K to produce antimony in an environmentally friendly manner. The results demonstrated the technical feasibility of producing antimony by this method without producing SO2 gas. Complete conversion of Sb2S3 was obtained at 1023 K in about 1000 seconds and at 1123 K in less than 250 seconds using stibnite-carbon-lime mixtures with molar ratios Sb2S3:CaO:C = 1:3:3. It was found that the reduction proceeds through the formation of an intermediate oxide SbO2, which is subsequently reduced by CO(g to yield antimony metal and CaS. The kinetics of the Sb2S3 reduction was analyzed by using the equation ln(1-X = -kt. The activation energy was 233 kJ mol-1 in the temperature range of 973 to 1123 K. This value would correspond to an antimony catalyzed carbon oxidation by CO2.

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.

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.

Development of Na/sup 123/I pharmaceutical from antimony target

Energy Technology Data Exchange (ETDEWEB)

Yongjian, L.; Qixun, S.; Dequn, S. (Shanghai Inst. of Nuclear Research, Academia Sinica, Shanghai (China))

A new method for the production of Na/sup 123/I is described. It is produced by the /sup 121/Sb(..cap alpha..,2n)/sup 123/I nuclear reaction and using a natural antimony target prepared by electroplating in a bath of antimony oxide and hydrofluoric acid. The target is irradiated with 32MeV ..cap alpha..-beams then transferred to a dry distillation apparatus and the iodide evolved and absorbed in NaOH. Quality control is by paper chromatography.

Influence of antimony on the elctrochemical behaviour and the structure of the lead dioxide active mass of lead/acid batteries

Energy Technology Data Exchange (ETDEWEB)

Pavlov, D. (Central Lab. of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia (Bulgaria)); Dakhouche, A. (Central Lab. of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia (Bulgaria)); Rogachev, T. (Central Lab. of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia (Bulgaria))

1993-01-29

The effect of antimony on the formation of the skeleton structure of tubular electrodes filled with lead dioxide active mass (PAM) is investigated. Antimony is added as ions to the solution, as Sb[sub 2]O[sub 3] or Sb[sub 2]O[sub 5] to PAM, or as an additive to the electrode spine alloy. The effect of antimony on the crystallinity of PAM particles and agglomerates is examined. It is established that antimony increases the capacity of tubular powder electrodes when added either to the alloy or as antimony oxide to the PAM. It accelerates the processes of formation of the PAM skeleton structure and decreases the crystallinity of PAM particles and agglomerates. These effects of antimony are explained based on the concept of a gel-crystal structure for the PAM. Antimony improves the electron conductivity of gel zones. Its effect depends on the type and valency of the antimony ions, and on the density of the PAM. (orig.)

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...

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.

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...

Influence of sulfur, phosphorus, and antimony segregation on the intergranular hydrogen embrittlement of nickel

International Nuclear Information System (INIS)

Bruemmer, S.M.; Baer, D.R.; Jones, R.H.; Thomas, M.T.

1983-01-01

The effectiveness of sulfur, phosphorus, and antimony in promoting the intergranular embrittlement of nickel was investigated using straining electrode tests in 1N H 2 SO 4 at cathodic potentials. Sulfur was found to be the critical grain boundary segregant due to its large enrichment at grain boundaries (10 4 to 10 5 times the bulk content) and the direct relationship between sulfur coverage and hydrogeninduced intergranular failure. Phosphorus was shown to be significantly less effective than sulfur or antimony in inducing the intergranular hydrogen embrittlement of nickel. The addition of phosphoru to nickel reduced the tendency for intergranular fracture and improved ductility because phosphoru segregated strongly to grain interfaces and limited sulfur enrichment. The hydrogen embrittling potency of antimony was also less than that of sulfur while its segregation propensity was considerably less. It was found that the effectiveness of segregated phosphorus and antimony in prompting inter granular embrittlement vs that of sulfur could be expressed in terms of an equivalent grain boundary sulfur coverage. The relative hydrogen embrittling potencies of sulfur, phosphorus, and antimony are discussed in reference to general mechanisms for the effect of impurity segregation on hydrogeninduced intergranular fracture

The cariostatic mechanisms of fluoride

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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.

Characteristic electron energy losses in monoatomic antimony films on (110) and (112) tungsten faces

International Nuclear Information System (INIS)

Gorodetskij, D.A.; Gorchinskij, A.D.; Shevlyakov, S.A.

1981-01-01

Complex investigations of antimony condensation on a monoatomical clean surface of tungsten monocrystals are carried out. The completion of a physical antimony monolayer has been controlled by the methods of Auger-electron spectroscopy and slow electron diffraction. It is shown that at submonolayer coatings a collectivization of valent electrons occurs leading to appearance of peaks of surface and volumetric plasmons in the energy losses spectrum. The anomalous cencentrational dependence of antimony ionization peak intensity has been found. The origin of previously unexplored peaks in the energy losses spectrum is discussed [ru

Levels and risk factors of antimony contamination in human hair from an electronic waste recycling area, Guiyu, China.

Science.gov (United States)

Huang, Yue; Ni, Wenqing; Chen, Yaowen; Wang, Xiaoling; Zhang, Jingwen; Wu, Kusheng

2015-05-01

The primitive electronic waste (e-waste) recycling has brought a series of environmental pollutants in Guiyu, China. Antimony is one of the important metal contaminants and has aroused the global concerns recently. We aimed to investigate concentrations of antimony in human hair from Guiyu and compared them with those from a control area where no e-waste recycling exists, and assessed the potential risk factors. A total of 205 human hair samples from Guiyu and 80 samples from Jinping were collected for analysis. All volunteers were asked to complete a questionnaire including socio-demographic characteristics and other possible factors related to hair antimony exposure. The concentrations of hair antimony were analyzed using atomic absorption spectrophotometer. Our results indicated that the level of hair antimony in volunteers from Guiyu (median, 160.78; range, 6.99-4412.59 ng/g) was significantly higher than those from Jinping (median, 61.74; range, 2.98-628.43 ng/g). The residents who engaged in e-waste recycling activities in Guiyu had higher hair antimony concentrations than others (P recycling. Multiple stepwise regression analysis indicated that hair antimony concentrations were associated with education level (β = -0.064), the time of residence in Guiyu (β = 0.112), living house also served as e-waste workshop (β = 0.099), the work related to e-waste (β = 0.169), and smoking (β = 0.018). The elevated hair antimony concentrations implied that the residents in Guiyu might be at high risk of antimony contamination, especially the e-waste recycling workers. Work related to e-waste recycling activities and long-time residence in Guiyu contributed to the high hair antimony exposure.

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.

The effects of antimony doping on the surface structure of rutile TiO{sub 2}(110)

Energy Technology Data Exchange (ETDEWEB)

Bechstein, Ralf; Schuette, Jens; Kuehnle, Angelika [Fachbereich Physik, Universitaet Osnabrueck, Barbarastrasse 7, D-49076 Osnabrueck (Germany); Kitta, Mitsunori; Onishi, Hiroshi [Department of Chemistry, Kobe University, Rokko-dai, Nada-ku, Kobe 657-8501 (Japan)], E-mail: kuehnle@uos.de

2009-07-01

Titanium dioxide represents a very important wide bandgap photocatalyst that is known to be sensitized to visible light by transition metal doping. Antimony doping has been demonstrated to provide photocatalytic activity when codoped with chromium at an optimum dopant ratio [Sb]/[Cr] of about 1.5. Here, the role of antimony doping on the surface structure of rutile TiO{sub 2}(110) is studied using non-contact atomic force microscopy (NC-AFM) under ultra-high vacuum conditions. At first glance, the surface structure of antimony-doped TiO{sub 2}(110) resembles the structure of pristine TiO{sub 2}(110). However, in contrast to what is found in pristine TiO{sub 2}(110), a dense layer of protruding features is observed upon antimony doping, which is tentatively ascribed to antimony-rich clusters. Moreover, homogeneously distributed holes are found on the surface, which differ in depth and shape depending on the preparation conditions. Holes with depths ranging from a few up to more than a hundred monatomic steps are observed. These holes are explained by surface segregation of antimony during annealing, as the ionic radius of Sb{sup 3+} is considerably larger than the ionic radius of Ti{sup 4+}. Our finding provides an indication of why an antimony concentration larger than the optimum ratio results in decreased photocatalytic activity. Moreover, controlling annealing temperature seems to constitute a promising strategy for creating nanosized holes on TiO{sub 2} surfaces.

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

Redox substoichiometric isotope dilution analysis of metallic arsenic for antimony

International Nuclear Information System (INIS)

Kambara, Tomihisa; Yoshioka, Hiroe; Suzuki, Junsuke; Shibata, Yasue.

1979-01-01

In 1 M HCl solution Sb(III) reacts with N-benzoyl-N-phenylhydroxylamine (BPHA) to form a complex extractable into chloroform while the extraction of Sb(V) is negligible. The redox substoichiometric isotope dilution analysis based on this reaction was applied to the determination of antimony in metallic arsenic. After the dissolution of metallic arsenic, Sb(V) was separated from As(V) by a tribenzylamine extraction from 8 M HCl solution and the extracted Sb(V) was stripped into 0.5 M NaOH solution. Thereafter, all the Sb(V) were completely reduced to Sb(III) by bubbling SO 2 gas through 3 M HCl solution. As the substoichiometric reaction, the oxidation of Sb(III) to Sb(V) by a substoichiometric amount of potassium dichromate was used, followed by separation of these species by the BPHA extraction of Sb(III). The substoichiometric oxidation of Sb(III) was found to be quantitative over HCl concentration range from 0.8 to 1.2 M. The amount of antimony was determined by isotope dilution analysis using the method of carrier amount variation. By the present method the determination of as small as 0.36 μg antimony was accomplished with a good accuracy (relative error; 5.6%) and also the method was successfully applied to the determination of antimony in arsenic samples containing known amounts of Sb(III) and in metallic arsenic. The present method gives reliable results with the good accuracy and precision. (author)

High dose implantations of antimony for buried layer applications

International Nuclear Information System (INIS)

Gailliard, J.P.; Dupuy, M.; Garcia, M.; Roussin, J.C.

1978-01-01

Electrical and physical properties of high dose implantations of antimony in silicon have been studied for use in buried layer applications. The results have been obtained both on and oriented silicon wafers. Following implantations which lead to amorphization we perform an annealing at 600 0 C for 10 mn in order to recrystallize the layer. The observed electrical properties (μ, R) show that the concentration of electrically active antimony ions is greater than that predicted from the solubility of antimony in silicon. Further annealing (in the range 1050 0 - 1200 0 ) induces: firstly a precipitation of the Sb and secondly a diffusion and dissolution of the precipitates. There is a different evolution of the defects in the and silicon slices. T.E.M. reveals no defects in the wafers after one hour annealing at 1200 0 C, whereas defects and twins remain in wafers. Having obtained the evolution of R with time and temperature it is then determined the implantation and annealing conditions which lead to the low resistivity (R = 10) needed for buried layer applications. Results with very many industrially made devices are discussed

Study on antimony oxide self-assembled inside HZSM-5

International Nuclear Information System (INIS)

Li Bin; Li Shijie; Wang Yingxia; Li Neng; Liu Xiyao; Lin Bingxiong

2005-01-01

Sb/ZSM-5 was obtained by solid-state reaction with the mixture of Sb 2 O 3 and zeolite HZSM-5 under a dry nitrogen flow at 773K. Characterization of the treated zeolite was undertaken with XRD, 27 Al MAS NMR, BET, TGA and FT-IR. The results revealed that part of the antimony oxides migrated into the channels of zeolite, and decreased the Bronsted acid sites in Sb/ZSM-5 remarkably. The other part of antimony oxides together with the amorphous alumino-silicate in the products distributed on the external surface of zeolite ZSM-5 and modified it, while the framework of ZSM-5 in crystal phase was retained. The structure of occluded antimony oxide inside the channels of ZSM-5 was studied by XRD Rietveld method. The result showed that their structure can be described as a chain of non-perfect [Sb 5 O 5 (H 2 O) 2 ] n 5n+ , which is parallel to the straight channel of ZSM-5. There is about 0.6 [Sb 5 O 5 (H 2 O) 2 ] 5+ unit in every cell of the ZSM-5 on an average

Proton-activation technique for the determination of antimony

International Nuclear Information System (INIS)

Krivan, V.; Barth, P.

1979-01-01

Photon-activation analysis has been applied to the determination of antimony. Thick-target yields and analytical sensitivities are given for the indicator-radionuclides sup(119m)Te, sup(119g)Te, sup(121m)Te, sup(121g)Te, sup(123m)Te, sup(120m)Sb and sup(122g)Sb for proton energies between 9 and 25 MeV. In irradiations with a 5-μA beam for 5 hr, followed by a specific separation of the indicator-radionuclides, limits of detection at the ppm level can be achieved. Data are given for the most significant interfering reactions. Antimony was determined instrumentally in bismuth of very pure grade and the results are compared with those obtained from two independent techniques. (author)

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.

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

Varicella zoster virus reactivation during or immediately following treatment of tegumentary leishmaniasis with antimony compounds

Directory of Open Access Journals (Sweden)

Andrea Barbieri Barros

2014-07-01

Full Text Available Antimony compounds are the cornerstone treatments for tegumentary leishmaniasis. The reactivation of herpes virus is a side effect described in few reports. We conducted an observational study to describe the incidence of herpes zoster reactivation during treatment with antimony compounds. The global incidence of herpes zoster is approximately 2.5 cases per 1,000 persons per month (or 30 cases per 1,000 persons per year. The estimated incidence of herpes zoster in patients undergoing antimony therapy is higher than previously reported.

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.

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.

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 ...

Distribution of antimony in the oxide layer formed by potentiostatic oxidation of Pb-Sb alloy

Energy Technology Data Exchange (ETDEWEB)

Arifuku, F.; Yoneyama, H.; Tamura, H.

1979-09-01

The distribution of antimony within the oxide films on Pb-Sb alloy prepared by potentiostatic oxidation in H/sub 2/SO/sub 4/ solutions was examined by SIMS. The study of oxide films prepared by applying different potentials for three hours showed that two types of film were obtained depending on whether the potential was more negative or more positive than 1.5 V. Antimony profiles were obtained for films at several stages in the initial growth. It was found that antimony was retained in the oxide film at 1.5 V during both nucleation and two- or three-dimensional growth of PbO/sub 2/ and at 1.6 V during the lateral overlaps of three-dimensional centers of PbO/sub 2/. Relationships between the antimony distribution profiles and the oxide film growth are discussed. 8 figures, 1 table.

Antimony contamination, consequences and removal techniques: A review.

Science.gov (United States)

Li, Jiayu; Zheng, BoHong; He, Yangzhuo; Zhou, Yaoyu; Chen, Xiao; Ruan, Shan; Yang, Yuan; Dai, Chunhao; Tang, Lin

2018-07-30

A significant amount of antimony (Sb) enters into the environment every year because of the wide use of Sb compounds in industry and agriculture. The exposure to Sb, either direct consumption of Sb or indirectly, may be fatal to the human health because both antimony and antimonide are toxic. Firstly, the introduction of Sb chemistry, distribution and health threats are presented in this review, which is essential to the removal techniques. Then, we provide the recent and common techniques to remove Sb, including adsorption, coagulation/flocculation, membrane separation, electrochemical methods, ion exchange and extraction. Removal techniques concentrate on the advantages, drawbacks, economical efficiency and the recent achievements of each technique. We also take an overall consideration of experimental conditions, comparison criteria, and economic aspects. Copyright © 2018 Elsevier Inc. All rights reserved.

On-line lab-in-syringe cloud point extraction for the spectrophotometric determination of antimony.

Science.gov (United States)

Frizzarin, Rejane M; Portugal, Lindomar A; Estela, José M; Rocha, Fábio R P; Cerdà, Victor

2016-02-01

Most of the procedures for antimony determination require time-consuming sample preparation (e.g. liquid-liquid extraction with organic solvents), which are harmful to the environment. Because of the high antimony toxicity, a rapid, sensitive and greener procedure for its determination becomes necessary. The goal of this work was to develop an analytical procedure exploiting for the first time the cloud point extraction on a lab-in-syringe flow system aiming at the spectrophotometric determination of antimony. The procedure was based on formation of an ion-pair between the antimony-iodide complex and H(+) followed by extraction with Triton X-114. The factorial design showed that the concentrations of ascorbic acid, H2SO4 and Triton X-114, as well as second and third order interactions were significant at the 95% confidence level. A Box-Behnken design was applied to obtain the response surfaces and to identify the critical values. System is robust at the 95% confidence level. A linear response was observed from 5 to 50 µg L(-1), described by the equation A=0.137+0.050C(Sb) (r=0.998). The detection limit (99.7% confidence level), the coefficient of variation (n=5; 15 µg L(-1)) and the sampling rate was estimated at 1.8 µg L(-1), 1.6% and 16 h(-1), respectively. The procedure allows quantification of antimony in the concentrations established by environmental legislation (6 µg L(-1)) and it was successfully applied to the determination of antimony in freshwater samples and antileishmanial drugs, yielding results in agreement with those obtained by HGFAAS at the 95% confidence level. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

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.

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.

Treatment of visceral leishmaniasis: model-based analyses on the spread of antimony-resistant L. donovani in Bihar, India.

Directory of Open Access Journals (Sweden)

Anette Stauch

Full Text Available BACKGROUND: Pentavalent antimonials have been the mainstay of antileishmanial therapy for decades, but increasing failure rates under antimonial treatment have challenged further use of these drugs in the Indian subcontinent. Experimental evidence has suggested that parasites which are resistant against antimonials have superior survival skills than sensitive ones even in the absence of antimonial treatment. METHODS AND FINDINGS: We use simulation studies based on a mathematical L. donovani transmission model to identify parameters which can explain why treatment failure rates under antimonial treatment increased up to 65% in Bihar between 1980 and 1997. Model analyses suggest that resistance to treatment alone cannot explain the observed treatment failure rates. We explore two hypotheses referring to an increased fitness of antimony-resistant parasites: the additional fitness is (i disease-related, by causing more clinical cases (higher pathogenicity or more severe disease (higher virulence, or (ii is transmission-related, by increasing the transmissibility from sand flies to humans or vice versa. CONCLUSIONS: Both hypotheses can potentially explain the Bihar observations. However, increased transmissibility as an explanation appears more plausible because it can occur in the background of asymptomatically transmitted infection whereas disease-related factors would most probably be observable. Irrespective of the cause of fitness, parasites with a higher fitness will finally replace sensitive parasites, even if antimonials are replaced by another drug.

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

Antimony leaching in plastics from waste electrical and electronic equipment (WEEE) with various acids and gamma irradiation.

Science.gov (United States)

Tostar, Sandra; Stenvall, Erik; Boldizar, Antal; Foreman, Mark R St J

2013-06-01

There has been a recent interest in antimony since the availability in readily mined areas is decreasing compared to the amounts used. It is important in many applications such as flame retardants and in the production of polyester, which can trigger an investigation of the leachability of antimony from plastics using different acids. In this paper, different types of acids are tested for their ability to leach antimony from a discarded computer housing, made of poly(acrylonitrile butadiene styrene), which is a common plastic type used in electrical and electronic equipment. The acid solutions included sodium hydrogen tartrate (0.5M) dissolved in either dimethyl sulfoxide or water (at ca. 23°C and heated to ca. 105°C). The metal content after leaching was determined by inductively coupled plasma optical emission spectroscopy. The most efficient leaching medium was the heated solution of sodium hydrogen tartrate in dimethyl sulfoxide, which leached almost half of the antimony from the poly(acrylonitrile butadiene styrene). Gamma irradiation, which is proposed to improve the mechanical properties in plastics, was used here to investigate the influence of antimony leaching ability. No significant change in the amount of leached antimony could be observed. Copyright © 2013 Elsevier Ltd. All rights reserved.

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.

Predictors of an unsatisfactory response to pentavalent antimony in the treatment of American visceral leishmaniasis

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Santos Mácia A.

2002-01-01

Full Text Available Although treatment of visceral leishmaniasis with pentavalent antimony is usually successful, some patients require second-line drug therapy, most commonly with amphotericin B. To identify the clinical characteristics that predict an inadequate response to pentavalent antimony, a case-control study was undertaken in Teresina, Piaui, Brazil. Over a two-year period, there were 19 cases of VL in which the staff physicians of a hospital prescribed second-line therapy with amphotericin B after determining that treatment with pentavalent antimony had failed. The control group consisted of 97 patients that were successfully treated with pentavalent antimony. A chart review using univariate and multivariate analysis was performed. The cure rate was 90% with amphotericin B. The odds ratio for the prescription of amphotericin B was 10.2 for children less than one year old, compared with individuals aged over 10 years. Patients who presented coinfection had an OR of 7.1 while those on antibiotics had an OR of 2.8. These data support either undertaking a longer course of therapy with pentavalent antimony for children or using amphotericin B as a first-line agent for children and individuals with coinfections. It also suggests that chemoprophylaxis directed toward bacterial coinfection in small children with VL may be indicated.

Species-Specific Antimonial Sensitivity in Leishmania Is Driven by Post-Transcriptional Regulation of AQP1

Science.gov (United States)

Mandal, Goutam; Mandal, Srotoswati; Sharma, Mansi; Charret, Karen Santos; Papadopoulou, Barbara; Bhattacharjee, Hiranmoy; Mukhopadhyay, Rita

2015-01-01

Leishmania is a digenetic protozoan parasite causing leishmaniasis in humans. The different clinical forms of leishmaniasis are caused by more than twenty species of Leishmania that are transmitted by nearly thirty species of phlebotomine sand flies. Pentavalent antimonials (such as Pentostam or Glucantime) are the first line drugs for treating leishmaniasis. Recent studies suggest that pentavalent antimony (Sb(V)) acts as a pro-drug, which is converted to the more active trivalent form (Sb(III)). However, sensitivity to trivalent antimony varies among different Leishmania species. In general, Leishmania species causing cutaneous leishmaniasis (CL) are more sensitive to Sb(III) than the species responsible for visceral leishmaniasis (VL). Leishmania aquaglyceroporin (AQP1) facilitates the adventitious passage of antimonite down a concentration gradient. In this study, we show that Leishmania species causing CL accumulate more antimonite, and therefore exhibit higher sensitivity to antimonials, than the species responsible for VL. This species-specific differential sensitivity to antimonite is directly proportional to the expression levels of AQP1 mRNA. We show that the stability of AQP1 mRNA in different Leishmania species is regulated by their respective 3’-untranslated regions. The differential regulation of AQP1 mRNA explains the distinct antimonial sensitivity of each species. PMID:25714343

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...

LUMINESCENT PROPERTIES OF SILICATE GLASSES WITH CERIUM IONS AND ANTIMONY

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A. M. Klykova

2014-05-01

Full Text Available The paper deals with the results of an experimental study of luminescence excitation spectra and luminescence of silicate glasses containing cerium ions and antimony. The aim of this work was to study the features of the luminescence and the effect of UV irradiation and heat treatment on luminescence and the state of cerium ions and antimony in glass. We investigated glass system Na2O-ZnO-Al2O3-SiO2-NaF-NaBr with additives CeO2 and Sb2O3. Synthesis was carried out in platinum crucibles in the air at 14500C. The samples were polished glass plates with a thickness of 0.5-1 mm. UV irradiation was carried out with a mercury lamp having a wide range of radiation in the spectral range 240-390 nm. It was conducted in a Nabertherm muffle furnaces. Luminescence spectra and excitation spectra were measured using a spectrofluorimeter MPF-44A (PerkinElmer at the room temperature. Measured luminescence spectra were corrected in view of the spectral sensitivity of the photodetector for spectrofluorimeter. Adjustment of the excitation spectra for the spectral dependence of the intensity of the excitation source was not carried out. During the experiments it was found that in silicate glasses Sb3+ ions can exist in two energy states, which corresponds to a different environment with oxygen ions. Heat treatment of these glasses in an oxidizing atmosphere leads to an increase in ion concentration of Sb3+ ions with a greater amount of oxygen in the environment. In glasses containing antimony and cerium ions, ultraviolet irradiation causes a change in the valence of cerium ions and antimony, which is accompanied by luminescence quenching. Subsequent heat treatment of glass leads to the inverse processes and restore luminescence excitation spectra. The study of fluorescent properties of silicate glasses with cerium and antimony ions led to the conclusion of the practical significance of this work. Promising multifunctional materials can be created on the basis of

Zinc depletion promotes apoptosis-like death in drug-sensitive and antimony-resistance Leishmania donovani.

Science.gov (United States)

Saini, Shalini; Bharati, Kavita; Shaha, Chandrima; Mukhopadhyay, Chinmay K

2017-09-05

Micronutrients are essential for survival and growth for all the organisms including pathogens. In this manuscript, we report that zinc (Zn) chelator N,N,N',N'-tetrakis(2-pyridinylmethyl)-1,2-ethylenediamine (TPEN) affects growth and viability of intracellular pathogen Leishmania donovani (LD) by a concentration and time dependent manner. Simultaneous addition of zinc salt reverses the effect of TPEN. Further experiments provide evidence of apoptosis-like death of the parasite due to Zn-depletion. TPEN treatment enhances caspase-like activity suggesting increase in apoptosis-like events in LD. Specific inhibitors of cathepsin B and Endoclease G block TPEN-induced leishmanial death. Evidences show involvement of reactive oxygen species (ROS) potentially of extra-mitochondrial origin in TPEN-induced LD death. Pentavalent antimonials remained the prime source of treatment against leishmaniasis for several decades; however, antimony-resistant Leishmania is now common source of the disease. We also reveal that Zn-depletion can promote apoptosis-like death in antimony-resistant parasites. In summary, we present a new finding about the role of zinc in the survival of drug sensitive and antimony-resistant LD.

Morphology and photoresponse of crystalline antimony film grown on mica by physical vapor deposition

Directory of Open Access Journals (Sweden)

Shafa Muhammad

2016-09-01

Full Text Available Antimony is a promising material for the fabrication of photodetectors. This study deals with the growth of a photosensitive thin film by the physical vapor deposition (PVD of antimony onto mica surface in a furnace tube. The geometry of the grown structures was studied via scanning electron microscopy (SEM, X-ray diffraction (XRD, energy-dispersive X-ray spectroscopy (EDX and elemental diffraction analysis. XRD peaks of the antimony film grown on mica mostly matched with JCPDF Card. The formation of rhombohedral crystal structures in the film was further confirmed by SEM micrographs and chemical composition analysis. The Hall measurements revealed good electrical conductivity of the film with bulk carrier concentration of the order of 1022 Ω·cm-3 and mobility of 9.034 cm2/Vs. The grown film was successfully tested for radiation detection. The photoresponse of the film was evaluated using its current-voltage characteristics. These investigations revealed that the photosensitivity of the antimony film was 20 times higher than that of crystalline germanium.

Treatment of antimony mine drainage: challenges and opportunities with special emphasis on mineral adsorption and sulfate reducing bacteria.

Science.gov (United States)

Li, Yongchao; Hu, Xiaoxian; Ren, Bozhi

2016-01-01

The present article summarizes antimony mine distribution, antimony mine drainage generation and environmental impacts, and critically analyses the remediation approach with special emphasis on iron oxidizing bacteria and sulfate reducing bacteria. Most recent research focuses on readily available low-cost adsorbents, such as minerals, wastes, and biosorbents. It is found that iron oxides prepared by chemical methods present superior adsorption ability for Sb(III) and Sb(V). However, this process is more costly and iron oxide activity can be inhibited by plenty of sulfate in antimony mine drainage. In the presence of sulfate reducing bacteria, sulfate can be reduced to sulfide and form Sb(2)S(3) precipitates. However, dissolved oxygen and lack of nutrient source in antimony mine drainage inhibit sulfate reducing bacteria activity. Biogenetic iron oxide minerals from iron corrosion by iron-oxidizing bacteria may prove promising for antimony adsorption, while the micro-environment generated from iron corrosion by iron oxidizing bacteria may provide better growth conditions for symbiotic sulfate reducing bacteria. Finally, based on biogenetic iron oxide adsorption and sulfate reducing bacteria followed by precipitation, the paper suggests an alternative treatment for antimony mine drainage that deserves exploration.

Antimony distribution and mobility in topsoils and plants (Cytisus striatus, Cistus ladanifer and Dittrichia viscosa) from polluted Sb-mining areas in Extremadura (Spain)

International Nuclear Information System (INIS)

Murciego, A. Murciego; Sanchez, A. Garcia; Gonzalez, M.A. Rodriguez; Gil, E. Pinilla; Gordillo, C. Toro; Fernandez, J. Cabezas; Triguero, T. Buyolo

2007-01-01

A study about topsoil antimony distribution and mobility from the soils to the biomass has been afforded in three abandoned Sb mining areas located at Extremadura. Physico-chemical characteristics of the soils and total antimony levels were measured in soils and autochthonous plant species (Cytisus striatus, Cistus ladanifer and Dittrichia viscosa). Comparison with corresponding values in reference areas isolated from the mining activities is discussed. Antimony mobility in the soils was estimated by measuring the water extractable fraction; low results were obtained for the three soil areas, with no statistical differences. Plant ability to accumulate antimony was estimated by use of plant accumulation coefficients (PAC). Seasonal (spring vs. autumn) effects on the antimony content in the plant species. Cytisus striatus from Mari Rosa mine presented antimony excluder characteristics, whereas Dittrichia viscosa specimens growing in San Antonio mine showed a significant antimony bioaccumulation. - Bioaccumulation of antimony in vegetal species growing in mining areas

Antimony distribution and mobility in topsoils and plants (Cytisus striatus, Cistus ladanifer and Dittrichia viscosa) from polluted Sb-mining areas in Extremadura (Spain)

Energy Technology Data Exchange (ETDEWEB)

Murciego, A. Murciego [Area de Cristalografia y Mineralogia, Universidad de Extremadura, Avda. Elvas, s/n, E-06071 Badajoz (Spain); Sanchez, A. Garcia [IRNA-CSIC, Departamento de Geoquimica Ambiental, Aptdo. 257, Salamanca (Spain); Gonzalez, M.A. Rodriguez [Area de Cristalografia y Mineralogia, Universidad de Extremadura, Avda. Elvas, s/n, E-06071 Badajoz (Spain); Gil, E. Pinilla [Departamento de Quimica Analitica y Electroquimica, Facultad de Ciencias, Universidad de Extremadura, Avda. Elvas, s/n, E-06071 Badajoz (Spain)]. E-mail: epinilla@unex.es; Gordillo, C. Toro [Departamento de Quimica Analitica y Electroquimica, Facultad de Ciencias, Universidad de Extremadura, Avda. Elvas, s/n, E-06071 Badajoz (Spain); Fernandez, J. Cabezas [Area de Ecologia, Universidad de Extremadura, Avda. Elvas, s/n, E-06071 Badajoz (Spain); Triguero, T. Buyolo [Area de Ecologia, Universidad de Extremadura, Avda. Elvas, s/n, E-06071 Badajoz (Spain)

2007-01-15

A study about topsoil antimony distribution and mobility from the soils to the biomass has been afforded in three abandoned Sb mining areas located at Extremadura. Physico-chemical characteristics of the soils and total antimony levels were measured in soils and autochthonous plant species (Cytisus striatus, Cistus ladanifer and Dittrichia viscosa). Comparison with corresponding values in reference areas isolated from the mining activities is discussed. Antimony mobility in the soils was estimated by measuring the water extractable fraction; low results were obtained for the three soil areas, with no statistical differences. Plant ability to accumulate antimony was estimated by use of plant accumulation coefficients (PAC). Seasonal (spring vs. autumn) effects on the antimony content in the plant species. Cytisus striatus from Mari Rosa mine presented antimony excluder characteristics, whereas Dittrichia viscosa specimens growing in San Antonio mine showed a significant antimony bioaccumulation. - Bioaccumulation of antimony in vegetal species growing in mining areas.

Study of upscaling possibilities for antimony sulfide solid state sensitized solar cells

Science.gov (United States)

Nikolakopoulou, Archontoula; Raptis, Dimitrios; Dracopoulos, Vasilios; Sygellou, Lamprini; Andrikopoulos, Konstantinos S.; Lianos, Panagiotis

2015-03-01

Solid state solar cells of inverted structure were constructed by successive deposition of nanoparticulate titania, antimony sulfide sensitizer and P3HT on FTO electrodes with PEDOT:PSS:Ag as counter electrode. Sensitized photoanode electrodes were characterized by XRD, Raman, XPS, FESEM and UV-vis. Small laboratory scale cells were first constructed and optimized. Functional cells were obtained by annealing the antimony sulfide film either in air or in inert atmosphere. High short-circuit currents were recorded in both cases with air-annealed sample producing more current but lower voltage. Small unit cells were combined to form cell modules. Connection of unit cells in parallel increased current but not proportionally to that of the unit cell. Connection in series preserved current and generated voltage multiplication. Cells were constructed and studied under ambient conditions, without encapsulation. The results encourage upscaling of antimony sulfide solar cells.

Uranium accumulation in valentinite within the oxidation zone of an antimony occurrence

International Nuclear Information System (INIS)

Sergeev, I.P.; Kurilo, M.V.

1985-01-01

As a result of mineralogic-radiogeochemical study of real composition of oxidation zone of antimony occurrence represented by quartz - antimonite vien in silicificated sandstones the previousy undescribed phenomenon of uranium concentration in valentinite Sb 2 O 3 one of antimonite oxidation products has been found. According to the data of fission radiography the enrichment of valentinite with uranium is clearly seen, particularly of its concentrically zonal aggregates. The valentinite is the basic uranium mineral-concentrator in the oxidation zone, whereas in the initial mineral - antimonite as well as in the product of its more complete oxidation - stibiconite - uranium is lacking. Probably the crystallochemical properties of anhydrous antimony oxide (valentinite) by analogy with those for iron (goethite hematite) and titanium (leucoxene) are the most favourable for uranium adsorption as compared with high-water antimony oxides (stibiconite) or iron (limonite), which do not usually sorb uranium

Uranium accumulation in valentinite within the oxidation zone of an antimony occurrence

Energy Technology Data Exchange (ETDEWEB)

Sergeev, I.P.; Kurilo, M.V.

1985-01-01

As a result of mineralogic-radiogeochemical study of real composition of oxidation zone of antimony occurrence represented by quartz - antimonite vien in silicificated sandstones the previousy undescribed phenomenon of uranium concentration in valentinite Sb/sub 2/O/sub 3/ one of antimonite oxidation products has been found. According to the data of fission radiography the enrichment of valentinite with uranium is clearly seen, particularly of its concentrically zonal aggregates. The valentinite is the basic uranium mineral-concentrator in the oxidation zone, whereas in the initial mineral - antimonite as well as in the product of its more complete oxidation - stibiconite - uranium is lacking. Probably the crystallochemical properties of anhydrous antimony oxide (valentinite) by analogy with those for iron (goethite hematite) and titanium (leucoxene) are the most favourable for uranium adsorption as compared with high-water antimony oxides (stibiconite) or iron (limonite), which do not usually sorb uranium.

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

Leachability of antimony from energy ashes. Total contents, leachability and remedial suggestions; Lakning av antimon fraan energiaskor. Totalhalter, lakbarhet samt foerslag till aatgaerder

Energy Technology Data Exchange (ETDEWEB)

Baeckstroem, Mattias [Oerebro Univ. (Sweden)

2006-01-15

In the current project total concentrations for antimony in 31 energy ashes have been compiled. The average concentration of antimony in boiler fly ash and grate boiler fly ash is 192 and 1,140 mg/kg, respectively. The corresponding antimony concentrations for boiler ashes and grate bottom ashes are 86,5 and 61,8 mg/kg, respectively. Multivariate calculations clearly pointed out waste as the major source for antimony in ashes. The difference between total antimony concentration in fly ash and bottom ash is greatest for grate boilers, in average 18 times higher in the fly ash. The difference for CFB/BFB-boilers is only slightly more than 2. However, based on amount, 75% of the total antimony inventory is recovered in the fly ashes for both CFB/BFB and grate boilers. Eleven (eight of which were bottom ashes) out of the 31 samples exceeded the guidelines for inert waste. It is clear that the higher ionic strength in the solutions from the fly ashes contribute to decrease the solubility for critical minerals retaining antimony. In addition, the fly ashes have considerably larger effective surface able to sorb trace elements. A clear and positive covariance was discovered between aluminium and antimony. Furthermore, it was noted that antimony showed no typical anionic behaviour despite the fact that it according to the geochemical calculations should be present as SbO{sub 3}{sup -}. At L/S 10, a maximum of 1% of the total antimony concentration is leached. This should be compared to chloride that had 94% of the total concentration leached at L/S 10. There was no correlation between the leached antimony concentrations and the total antimony concentrations. The sequential extractions also suggest a low leachability for antimony from the ashes. In average only 9,6% is released at pH 7, 7,3% at pH 5, 3,6% during reducing conditions and 3,2% during oxidising conditions. In total, only 24% of the total antimony concentrations is released during the four extraction steps. The

Specific features of doping with antimony during the ion-beam crystallization of silicon

Energy Technology Data Exchange (ETDEWEB)

Pashchenko, A. S., E-mail: as.pashchenko@gmail.com; Chebotarev, S. N.; Lunin, L. S. [Russian Academy of Sciences, Southern Scientific Center (Russian Federation); Irkha, V. A. [Special Engineering and Technology Department “Inversiya” Ltd. (Russian Federation)

2016-04-15

A method of doping during the growth of thin films by ion-beam crystallization is proposed. By the example of Si and Sb, the possibility of controllably doping semiconductors during the ion-beam crystallization process is shown. A calibrated temperature dependence of the antimony vapor flow rate in the range from 150 to 400°C is obtained. It is established that, an increase in the evaporator temperature above 200°C brings about the accumulation of impurities in the layer growth direction. Silicon layers doped with antimony to a concentration of 10{sup 18} cm{sup –3} are grown. It is shown that, as the evaporator temperature is increased, the efficiency of the activation of antimony in silicon nonlinearly decreases from ~10{sup 0} to ~10{sup –3}.

Anodic stripping voltammetry of antimony using gold nanoparticle-modified carbon screen-printed electrodes

International Nuclear Information System (INIS)

Dominguez Renedo, Olga; Arcos Martinez, M. Julia

2007-01-01

Carbon screen-printed electrodes (CSPE) modified with gold nanoparticles present an interesting alternative in the determination of antimony using differential pulse anodic stripping voltammetry. Metallic gold nanoparticles deposits have been obtained by direct electrochemical deposition. Scanning electron microscopy measurements show that the electrochemically synthesized gold nanoparticles are deposited in aggregated form. Any undue effects caused by the presence of foreign ions in the solution were also analyzed to ensure that common interferents in the determination of antimony by ASV. The detection limit for Sb(III) obtained was 9.44 x 10 -10 M. In terms of reproducibility, the precision of the above mentioned method in %R.S.D. values was calculated at 2.69% (n = 10). The method was applied to determine levels of antimony in seawater samples and pharmaceutical preparations

Co-doping with antimony to control phosphorous diffusion in germanium

KAUST Repository

Tahini, H. A.

2013-02-15

In germanium, phosphorous and antimony diffuse quickly and as such their transport must be controlled in order to design efficient n-typed doped regions. Here, density functional theory based calculations are used to predict the influence of double donor co-doping on the migration activation energies of vacancy-mediated diffusion processes. The migration energy barriers for phosphorous and antimony were found to be increased significantly when larger clusters involving two donor atoms and a vacancy were formed. These clusters are energetically stable and can lead to the formation of even larger clusters involving a number of donor atoms around a vacancy, thereby affecting the properties of devices.

Increased biliary excretion of glutathione is generated by the glutathione-dependent hepatobiliary transport of antimony and bismuth.

Science.gov (United States)

Gyurasics, A; Koszorús, L; Varga, F; Gregus, Z

1992-10-06

We have recently demonstrated that the hepatobiliary transport of arsenic is glutathione-dependent and is associated with a profound increase in biliary excretion of glutathione (GSH), hepatic GSH depletion and diminished GSH conjugation (Gyurasics A, Varga F and Gregus Z, Biochem Pharmacol 41: 937-944 and Gyurasics A, Varga F and Gregus Z, Biochem Pharmacol 42: 465-468, 1991). The present studies in rats aimed to determine whether antimony and bismuth, other metalloids in group Va of the periodic table, also possess similar properties. Antimony potassium tartrate (25-100 mumol/kg, i.v.) and bismuth ammonium citrate (50-200 mumol/kg, i.v.) increased up to 50- and 4-fold, respectively, the biliary excretion of non-protein thiols (NPSH). This resulted mainly from increased hepatobiliary transport of GSH as suggested by a close parallelism in the biliary excretion of NPSH and GSH after antimony or bismuth administration. Within 2 hr, rats excreted into bile 55 and 3% of the dose of antimony (50 mumol/kg, i.v.) and bismuth (150 mumol/kg, i.v.), respectively. The time courses of the biliary excretion of these metalloids and NPSH or GSH were strikingly similar suggesting co-ordinate hepatobiliary transport of the metalloids and GSH. However, at the peak of their excretion, each molecule of antimony or bismuth resulted in a co-transport of approximately three molecules of GSH. Diethyl maleate, indocyanine green and sulfobromophthalein (BSP), which decreased biliary excretion of GSH, significantly diminished excretion of antimony and bismuth into bile indicating that hepatobiliary transport of these metalloids is GSH-dependent. Administration of antimony, but not bismuth, decreased hepatic GSH level by 30% and reduced the GSH conjugation and biliary excretion of BSP. These studies demonstrate that the hepatobiliary transport of trivalent antimony and bismuth is GSH-dependent similarly to the hepatobiliary transport of trivalent arsenic. Proportionally to their biliary

Phosphors for X-ray intensification screens

International Nuclear Information System (INIS)

Rebatin, J.G.

1980-01-01

An improved rare earth oxyhalide phosphor for x-ray intensification screens is described. The phosphors, of formula LnOX.T where Ln = La or Gd, X = Cl or Br and T = Tm or Tb, are mixed with a small amount of a trivalent antimony compound. The addition of antimony overcomes ageing due to attack by atmospheric moisture and renders the phosphor freeflowing so that dispersions can be readily made. Preferably the phosphor is washed with an aqueous solution of the antimony compound and the compound is the fluoride, chloride or butoxide, or potassium antimony tartrate. (U.K.)

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.

Influence of cooling rate and antimony addition content on graphite morphology and mechanical properties of a ductile iron

Directory of Open Access Journals (Sweden)

Liu Zhe

2012-05-01

Full Text Available Cooling rate and inoculation practice can greatly affect the graphite morphology of ductile irons. In the present research, the effects of the cooling rate and antimony addition on the graphite morphology and mechanical properties of ductile irons have been studied. Three ductile iron castings were prepared through solidification under cooling conditions S (slow, M (medium and F (fast. The cooling rates around the equilibrium eutectic temperature (1,150 ℃ for these cooling conditions (S, M and F were set at 0.21 ℃·min-1, 0.32 ℃·min-1 and 0.37 ℃·min-1, respectively. In addition, four ductile iron castings were prepared by adding 0.01%, 0.02%, 0.03% and 0.04% (by weight antimony, respectively under the slow cooling condition. The results show that the nodularity index, tensile strength and hardness of the ductile iron castings without antimony addition are all improved with the increase of cooling rate, while the ductile iron casting solidified under the medium cooling rate possesses the largest number of graphite nodules. Furthermore, for the four antimony containing castings, the graphite morphology and tensile strength are also improved by the antimony additions, and the effect of antimony addition is intensified when the addition increases from 0.01% to 0.03%. Moreover, the rare earth elements (REE/antimony ratio of 2 appears to be the most effective for fine nodular graphite formation in ductile iron.

Alimentary fluoride intake in preschool children

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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

Antimony sulfide thin films prepared by laser assisted chemical bath deposition

International Nuclear Information System (INIS)

Shaji, S.; Garcia, L.V.; Loredo, S.L.; Krishnan, B.

2017-01-01

Highlights: • Antimony sulfide thin films were prepared by normal CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • These films were photoconductive. - Abstract: Antimony sulfide (Sb_2S_3) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb_2S_3 thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb_2S_3 thin films for optoelectronic applications.

Antimony sulfide thin films prepared by laser assisted chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); Garcia, L.V. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); Loredo, S.L. [Centro de Investigación en Materiales Avanzados (CIMAV), Unidad Monterrey, PIIT, Apodaca, Nuevo León (Mexico); Krishnan, B. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); and others

2017-01-30

Highlights: • Antimony sulfide thin films were prepared by normal CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • These films were photoconductive. - Abstract: Antimony sulfide (Sb{sub 2}S{sub 3}) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb{sub 2}S{sub 3} thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb{sub 2}S{sub 3} thin films for optoelectronic applications.

Simultaneous analysis of arsenic, antimony, selenium and tellurium in environmental samples using hydride generation ICPMS

International Nuclear Information System (INIS)

Jankowski, L.M.; Breidenbach, R.; Bakker, I.J.I.; Epema, O.J.

2009-01-01

Full text: A quantitative method for simultaneous analysis of arsenic, antimony, selenium and tellurium in environmental samples is being developed using hydride generation ICPMS. These elements must be first transformed into hydride-forming oxidation states. This is particularly challenging for selenium and antimony because selenium is susceptible to reduction to the non-hydride-forming elemental state and antimony requires strong reducing conditions. The effectiveness of three reducing agents (KI, thiourea, cysteine) is studied. A comparison is made between addition of reducing agent to the sample and addition of KI to the NaBH 4 solution. Best results were obtained with the latter approach. (author)

Extraction of antimony and arsenic from sulphidic concentrates

Directory of Open Access Journals (Sweden)

BalហPeter

2000-09-01

Full Text Available The efficiency of both mineral processing and extractive metallurgy of minerals depends on the separation of individual mineral components and on the exposure of their surface. The production of flotation concentrates, with particle sizes of tens of microns, is not sufficient for many hydrometallurgical processes to operate at their optimum. As a consequence, metallurgical plants require for the effective processing high temperatures and pressures and some sort of concentrate pretreatment. Mechanical activation is an innovative procedure where an improvement in hydrometallurgical processes can be attained via a combination of new surface area and formation of crystalline defects in minerals. The lowering of reaction temperatures, the increase of rate and amount of solubility, preparation of water soluble compounds, the necessity for simpler and less expensive reactors and shorter reaction times are some of the advantages of mechanical activation. The environmental aspects of these processes are particularly attractive.This paper is devoted to the examples of application of mechanochemical treatment in the processing of sulfidic concentrates. The sulphide concentrates of various origin (Peru, Chile, Slovakia were succesfully tested for antimony and arsenic extraction. The mechanochemical treatment improve the degree of recovery and the rate of leaching of both metals. Two modes of mechanochemical treatment were tested: the mechanical activation before leaching and the mechanochemical leaching which integrates mechanical activation and leaching into a common step. The flowsheet consisted of mechanochemical leaching in an attritor and further operations as filtration, cementation, antimony precipitation, crystallization and arsenic precipitation. The pilot plant unit was designed for 500 kg per day feed of tetrahedrite concentrate. For the antimony extraction, electrowinning has also been considered. The residue which is a CuAgAu concentrate was

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

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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.

Investigation of the effect of some parameters on the degree of leaching antimony from stibnite

Directory of Open Access Journals (Sweden)

Remeteiová Dagmar

1998-12-01

Full Text Available The paper presents results of experiments of agitation leaching of antimony from stibnite in alkaline solutions of Na2S +NaOH. The influence of different solution solutions ratio of the reacting phases and of different rate of stirring on the degree of leaching of antimony was investigated.

Comparison of modification with strontium and the refining with antimony in A 356 aluminium alloys

International Nuclear Information System (INIS)

Fuoco, Ricardo; Correa, Edison Roberto; Correa, Alzira V.O.; Bocalini Junior, Mario

1992-01-01

Strontium and Antimony treated A356 aluminium alloy samples were metallographically characterized in the as cast and solution and aged conditions. Antimony treated alloy has shown slower spheroidizing kinetics of the Silicon particles during solution treatment, lower porosity level and higher tensile strength and elongation than Strontium treated one. (author)

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 CHARACTERIZATION OF STRONTIUM FLUORIDE POWDERS ACTIVATED BY NEODYMIUM FLUORIDE

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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

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 ...

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 ...

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 ...

Dehydrogenation and concurrent isomerization of n-butenes on mixed tin and antimony oxide catalysts

Energy Technology Data Exchange (ETDEWEB)

Irvine, E.A.; Taylor, D.

1978-01-01

The dehydrogenation and concurrent isomerization of n-butenes on mixed tin and antimony oxide catalysts which had been outgassed at 698/sup 0/K were carried out in the presence of oxygen at 474/sup 0/K, and the initial approximately zero-order rates of 1,3-butadiene formation and rates of isomerization were used as a measure of catalytic activity to construct activity patterns as a function of catalyst composition. A comparison of the patterns with those for the isomerization of 3,3-dimethyl-1-butene and for the selective oxidation of propane on the same catalysts indicated that the dehydrogenation of 1-butene involves a m-allyl intermediate, but isomerization occurs through carbonium ion formation. For the cis- and trans-isomers, both reactions apparently occurred via a common allyl (but not m-allyl) intermediate. Dehydrogenation to butadiene decreased in the order 1-butene > cis-2-butene trans-2-butene and was maximum at 10% antimony for 1-butene and 21% antimony for 2-butene. Isomerization was always slower than dehydrogenation and showed two maEima, at 21 (or 27%) and at 75% antimony.

Antimony doped barium strontium ferrite perovskites as novel cathodes for intermediate-temperature solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Ling, Yihan, E-mail: lyhyy@mail.ustc.edu.cn [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, 221116 (China); Lu, Xiaoyong [China Anhui Key Laboratory of Low Temperature Co-fired Materials, Department of Chemistry, Huainan Normal University, Huainan, Anhui, 232001 (China); Niu, Jinan; Chen, Hui [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, 221116 (China); Ding, Yanzhi [China Anhui Key Laboratory of Low Temperature Co-fired Materials, Department of Chemistry, Huainan Normal University, Huainan, Anhui, 232001 (China); Ou, Xuemei [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, 221116 (China); Zhao, Ling [Department of Material Science and Chemistry, China University of Geosciences, Wuhan, 430074 (China)

2016-05-05

Antimony was doped to barium strontium ferrite to produce ferrite-based perovskites with a composition of Ba{sub 0.5}Sr{sub 0.5}Fe{sub 1−x}Sb{sub x}O{sub 3−δ} (x = 0.0, 0.05, 0.1) as novel cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The perovskite properties including oxygen nonstoichiometry (δ), mean valence of B-site, tolerance factors, thermal expansion coefficient (TEC) and electrical conductivity (σ) are explored as a function of antimony content. By defect chemistry analysis, the TECs decrease since the variable oxygen vacancy concentration is decreased by Sb doping, and σ decreases with x due to the reduced charge concentration of Fe{sup 4+} content. Consequently, the electrochemical performance was substantially improved and the interfacial polarization resistance was reduced from 0.213 to 0.120 Ωcm{sup 2} at 700 °C with Sb doping. The perovskite with x = 1.0 is suggested as the most promising composition as SOFC cathode material. - Highlights: • Antimony is doped to barium strontium ferrite to produce novel cathodes. • δ, TECs and σ are evaluated as a function of antimony content. • The electrochemical performance is substantially improved with antimony doping.

Tin dioxide sol-gel derived films doped with platinum and antimony deposited on porous silicon

NARCIS (Netherlands)

Savaniu, C.; Arnautu, A.; Cobianu, C.; Craciun, G.; Flueraru, C.; Zaharescu, M.; Parlog, C.; Paszti, F.; van den Berg, Albert

1999-01-01

SnO2 sol-gel derived thin films doped simultaneously with Pt and Sb are obtained and reported for the first time. The Sn sources were tin(IV) ethoxide or tin(II) ethylhexanoate, while hexachloroplatinic acid (H2PtCl6) and antimony chloride (SbCl3) were used as platinum and antimony sources,

Molecular Preadaptation to Antimony Resistance in Leishmania donovani on the Indian Subcontinent.

Science.gov (United States)

Dumetz, F; Cuypers, B; Imamura, H; Zander, D; D'Haenens, E; Maes, I; Domagalska, M A; Clos, J; Dujardin, J-C; De Muylder, G

2018-04-25

Antimonials (Sb) were used for decades for chemotherapy of visceral leishmaniasis (VL). Now abandoned in the Indian subcontinent (ISC) because of Leishmania donovani resistance, this drug offers a unique model for understanding drug resistance dynamics. In a previous phylogenomic study, we found two distinct populations of L. donovani : the core group (CG) in the Gangetic plains and ISC1 in the Nepalese highlands. Sb resistance was only encountered within the CG, and a series of potential markers were identified. Here, we analyzed the development of resistance to trivalent antimonials (Sb III ) upon experimental selection in ISC1 and CG strains. We observed that (i) baseline Sb III susceptibility of parasites was higher in ISC1 than in the CG, (ii) time to Sb III resistance was higher for ISC1 parasites than for CG strains, and (iii) untargeted genomic and metabolomic analyses revealed molecular changes along the selection process: these were more numerous in ISC1 than in the CG. Altogether these observations led to the hypothesis that CG parasites are preadapted to Sb III resistance. This hypothesis was experimentally confirmed by showing that only wild-type CG strains could survive a direct exposure to the maximal concentration of Sb III The main driver of this preadaptation was shown to be MRPA , a gene involved in Sb III sequestration and amplified in an intrachromosomal amplicon in all CG strains characterized so far. This amplicon emerged around 1850 in the CG, well before the implementation of antimonials for VL chemotherapy, and we discuss here several hypotheses of selective pressure that could have accompanied its emergence. IMPORTANCE The "antibiotic resistance crisis" is a major challenge for scientists and medical professionals. This steady rise in drug-resistant pathogens also extends to parasitic diseases, with antimony being the first anti- Leishmania drug that fell in the Indian subcontinent (ISC). Leishmaniasis is a major but neglected infectious

Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: arsenic, manganese, fluoride, iron, and uranium.

Science.gov (United States)

Bacquart, Thomas; Frisbie, Seth; Mitchell, Erika; Grigg, Laurie; Cole, Christopher; Small, Colleen; Sarkar, Bibudhendra

2015-06-01

In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic

Spectrophotometric procedure using rhodamine B for determination of submicrogram quantities of antimony in rocks

Science.gov (United States)

Schnepfe, M.M.

1973-01-01

A spectrophotometric procedure using Rhodamine B is given for the determination of antimony in mineralized rocks after its separation as stibine. A study of the Rhodamine B reaction points to the importance of the order of addition of reagents in enhancing sensitivity and increasing the stability of the system. The tolerance of some 26 elements is established for the overall procedure. Although the limit of determination is approximately 0??5 ppm Sb in a 0??2-g sample, the procedure is intended primarily for screening samples containing more than 1 ppm Sb. In pure solutions 0??1 ??g of antimony can be determined with a relative standard deviation of 25%. For >0??2 ??g of antimony a relative standard deviation of 15% or less can be expected. ?? 1973.

Conceptual design for treatment of mining and metallurgical wastewaters which contains arsenic and antimony

Directory of Open Access Journals (Sweden)

Željko Kamberović

2012-12-01

Full Text Available This paper presents a preliminary design for treatment of mining and metallurgical wastewaters (MMW from the basin of antimony “Zajača“, which contains high concentrations of arsenic and antimony. MMW have been investigated in laboratory, due to large difference in concentrations of pollutants. Metallurgical wastewaters were treated using iron (II-sulfate and lime milk used to adjust the pH value at 7. After chemical treatment of metallurgical wastewater and its joining with mining wastewater, residual amount of arsenic in water was below maximum allowed concentrations, while the concentration of antimony, remained above the maximum allowed value. The final phase of purification process was performed using ion exchange resin. After treatment of MMW, they can be used as technical water in the smelting process of secondary raw lead materials.

Antimony content of macrofungi from clean and polluted areas

Czech Academy of Sciences Publication Activity Database

Borovička, J.; Řanda, Zdeněk; Jelínek, E.

2006-01-01

Roč. 64, č. 11 (2006), s. 1837-1844 ISSN 0045-6535 Institutional research plan: CEZ:AV0Z10480505 Keywords : mushrooms * antimony pollution * bioaccumulation Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.442, year: 2006

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.

Science.gov (United States)

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

Science.gov (United States)

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.

Segregation of antimony in InP in MOVPE

Energy Technology Data Exchange (ETDEWEB)

Weeke, Stefan

2008-07-01

In this work the segregation of antimony in indium phosphide in metal organic vapour phase epitaxy (MOVPE)was systematically investigated. Therefore phosphine stabilized InP surfaces were treated with tri-methyl-antimony (TMSb) in MOVPE. An antimony rich Sb/InP surface was established, showing a typical spectra for the antimonides observed in reflectance anisotropy spectroscopy (RAS).Adsorption and desorption of antimony are investigated, as well as the incorporation of Sb during overgrowth of the Sb/InP surface with InP. Therefore the growth parameters temperature, TMSb partial pressure and treatment time are varied and their influence investigated. The experiments are monitored in-situ with RAS, the achieved data is correlated with ex-situ characterisation such as X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS). It is shown that under treatment with TMSb a stable Sb/InP surface is formed within seconds, which does not change under further TMSb treatment. This process is rarely influenced by the TMSb partial pressure. On the contrary, the desorption of Sb is a very slow process. Two main processes can be distinguished: The desorption of excess Sb from the surface and the formation of the MOVPE prepared InP (2 x 1) surface. The reaction velocity of adsorption and desorption increases with temperature. Above a critical value the increase of TMSb partial pressure has no influence on the time for desorption. During overgrowth of the Sb/InP surface the opposite temperature dependence is observed: with increasing growth temperature the typical spectra for antimonides is observed longer. An analysis of the grown samples with XRD and SIMS showed the formation of an InPSb double quantum well. One layer is formed at the interface, the second one 50 nm-120 nm deep in the InP. The location of the 2nd InPSb layer can be correlated with the vanishing of the Sb signature in RAS. The distance between the quantum wells increases with growth temperature, until it

Segregation of antimony in InP in MOVPE

International Nuclear Information System (INIS)

Weeke, Stefan

2008-01-01

In this work the segregation of antimony in indium phosphide in metal organic vapour phase epitaxy (MOVPE)was systematically investigated. Therefore phosphine stabilized InP surfaces were treated with tri-methyl-antimony (TMSb) in MOVPE. An antimony rich Sb/InP surface was established, showing a typical spectra for the antimonides observed in reflectance anisotropy spectroscopy (RAS).Adsorption and desorption of antimony are investigated, as well as the incorporation of Sb during overgrowth of the Sb/InP surface with InP. Therefore the growth parameters temperature, TMSb partial pressure and treatment time are varied and their influence investigated. The experiments are monitored in-situ with RAS, the achieved data is correlated with ex-situ characterisation such as X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS). It is shown that under treatment with TMSb a stable Sb/InP surface is formed within seconds, which does not change under further TMSb treatment. This process is rarely influenced by the TMSb partial pressure. On the contrary, the desorption of Sb is a very slow process. Two main processes can be distinguished: The desorption of excess Sb from the surface and the formation of the MOVPE prepared InP (2 x 1) surface. The reaction velocity of adsorption and desorption increases with temperature. Above a critical value the increase of TMSb partial pressure has no influence on the time for desorption. During overgrowth of the Sb/InP surface the opposite temperature dependence is observed: with increasing growth temperature the typical spectra for antimonides is observed longer. An analysis of the grown samples with XRD and SIMS showed the formation of an InPSb double quantum well. One layer is formed at the interface, the second one 50 nm-120 nm deep in the InP. The location of the 2nd InPSb layer can be correlated with the vanishing of the Sb signature in RAS. The distance between the quantum wells increases with growth temperature, until it

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.

First-Principles Study of Antimony Doping Effects on the Iron-Based Superconductor CaFe(SbxAs1-x)2

Science.gov (United States)

Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; Kuroki, Kazuhiko

2015-09-01

We study antimony doping effects on the iron-based superconductor CaFe(SbxAs1-x)2 by using the first-principles calculation. The calculations reveal that the substitution of a doped antimony atom into As of the chainlike As layers is more stable than that into FeAs layers. This prediction can be checked by experiments. Our results suggest that doping homologous elements into the chainlike As layers, which only exist in the novel 112 system, is responsible for rising up the critical temperature. We discuss antimony doping effects on the electronic structure. It is found that the calculated band structures with and without the antimony doping are similar to each other within our framework.

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

Determination of barium and antimony in gun shot residues by neutron activation analysis

International Nuclear Information System (INIS)

Charuchinda, A.

1975-01-01

The antimony contents on both hands of 7 persons before and after firing an automatic pistol were determined by instrumental neutron activation analysis. The gun shot residues were removed from hands by a 4% solution of cellulose acetate in acetone. The average content of antimony on both hands before firing obtained from 70 measurements (35 from each hand) was 0.040 ± 0.010 micro gram, whereas the average contents on the right and the left hands after 1 firing were 0.385 ± 0.036 and 0.144 ± 0.029 micro gram respectively. The ration of the antimony contents after 1 firing to the normal level (before firing) was 9.9 for the right and 3.6 for the left. No significant difference was observed between male and female, smoker and non-smoker. The antimony content after several firings was not much different from that of 1 firing and it reduced to the normal level within 2 days after firing. The barium contents before and after firing were studied from one person. Barium was precipitated as Ba SO 4 before counting. An average contents of 0.936 ± 0.551 micro gram for both hands before firing, 4.092 ± 2.687 micro gram for the right hand and 1.363 ± 0.879 micro gram for the left hand after 1 firing were found

Zhao Tiancong——A MONUMENT TO ANTIMONY IN CHINA

Institute of Scientific and Technical Information of China (English)

无

1992-01-01

Professor Zhao Tiancong is a famous specialist of our country in nonferrous merallurgy field and a doctoral teacher of Central South University of Technology. He has been devoting diligently his life to the development of the antimony metallurgy.

Intrachromosomal amplification, locus deletion and point mutation in the aquaglyceroporin AQP1 gene in antimony resistant Leishmania (Viannia guyanensis.

Directory of Open Access Journals (Sweden)

Rubens Monte-Neto

2015-02-01

Full Text Available Antimony resistance complicates the treatment of infections caused by the parasite Leishmania.Using next generation sequencing, we sequenced the genome of four independent Leishmania guyanensis antimony-resistant (SbR mutants and found different chromosomal alterations including aneuploidy, intrachromosomal gene amplification and gene deletion. A segment covering 30 genes on chromosome 19 was amplified intrachromosomally in three of the four mutants. The gene coding for the multidrug resistance associated protein A involved in antimony resistance was also amplified in the four mutants, most likely through chromosomal translocation. All mutants also displayed a reduced accumulation of antimony mainly due to genomic alterations at the level of the subtelomeric region of chromosome 31 harboring the gene coding for the aquaglyceroporin 1 (LgAQP1. Resistance involved the loss of LgAQP1 through subtelomeric deletions in three mutants. Interestingly, the fourth mutant harbored a single G133D point mutation in LgAQP1 whose role in resistance was functionality confirmed through drug sensitivity and antimony accumulation assays. In contrast to the Leishmania subspecies that resort to extrachromosomal amplification, the Viannia strains studied here used intrachromosomal amplification and locus deletion.This is the first report of a naturally occurred point mutation in AQP1 in antimony resistant parasites.

Determination of total antimony and inorganic antimony species by hydride generation in situ trapping flame atomic absorption spectrometry: a new way to (ultra)trace speciation analysis

Energy Technology Data Exchange (ETDEWEB)

Henryk Matusiewicz; Magdalena Krawczyk

2008-07-01

The analytical performance of non-chromatographic coupled hydride generation, integrated atom trap (HG-IAT) atomizer flame absorption spectrometry (FAAS) systems were evaluated for the speciation analysis of antimony in environmental samples. Antimony, using formation of stibine (SbH{sub 3}) vapors were atomized in an air-acetylene flame-heated IAT. A new design of HG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangements was investigated. For the estimation of Sb(III) and Sb(V) concentrations in samples, the difference between the analytical sensitivities of the absorbance signals obtained for antimony hydride without and with previous treatment of samples with L-cysteine can be used. The concentration of Sb(V) was calculated by the difference between total Sb and Sb(III). A dramatic improvement in detection limit was achieved compared with that obtained using either of the atom trapping techniques, presented above, separately. This novel approach decreases the detection limit down to low pg mL{sup -1} levels. The concentration detection limit, defined as 3 times the blank standard deviation was 0.2 ng mL{sup -1}. For a 120 s in situ pre-concentration time , sensitivity enhancement compared to flame AAS, was 550 fold for Sb, using hydride generation-atom trapping technique. The accuracy of the method was verified by the use of certified reference materials (NIST SRM 2704 Buffalo River Sediment, SRM 2710 Montana Soil, SRM 1633a Coal Fly Ash, SRM 1575 Pine Needles, SRM 1643e Trace Elements in Water) and by aqueous standard calibration technique. The measured Sb content, in reference materials, were in satisfactory agreement with the certified values. The hyphenated technique was applied for antimony determinations in soil, sediment, coal fly ash, sewage and river water.

Organic ligand-induced dissolution kinetics of antimony trioxide

Institute of Scientific and Technical Information of China (English)

Xingyun Hu; Mengchang He

2017-01-01

The influence of low-molecular-weight dissolved organic matter (LMWDOM) on the dissolution rate of Sb2O3 was investigated.Some representative LMWDOMs with carboxyl,hydroxyl,hydrosulfuryl and amidogen groups occurring naturally in the solution were chosen,namely oxalic acid,citric acid,tartaric acid,EDTA,salicylic acid,phthalandione,glycine,thiolactic acid,xylitol,glucose and catechol.These LMWDOMs were dissolved in inert buffers at pH =3.7,6.6 and 8.6 and added to powdered Sb2O3 in a stirred,thermostatted reactor (25℃).The addition of EDTA,tartaric acid,thiolactic acid,citric acid and oxalic acid solutions at pH 3.7 and catechol at pH 8.6 increased the rate of release of antimony.In the 10 mmol/L thiolactic acid solution,up to 97％ by mass of the antimony was released after 120 min reaction.There was no effect on the dissolution of Sb2O3 for the other ligands.A weak correlation between dissolution rate with the dissociation constant of ligands and the stability of the dissolved complex was also found.All the results showed that the extent of the promoting effect of ligands on the dissolution of Sb2O3 was not determined by the stability of the dissolved complex,but by the dissociation constant of ligands and detachment rate of surface chelates from the mineral surface.This study can not only help in further understanding the effect of individual low-molecular-weight organic ligands,but also provides a reference to deduce the effect of natural organic matters with oxygen-bearing functional groups on the dissolution of antimony oxide minerals.

Review on fluoride-releasing restorative materials--fluoride release and uptake characteristics, antibacterial activity and influence on caries formation.

Science.gov (United States)

Wiegand, Annette; Buchalla, Wolfgang; Attin, Thomas

2007-03-01

The purpose of this article was to review the fluoride release and recharge capabilities, and antibacterial properties, of fluoride-releasing dental restoratives, and discuss the current status concerning the prevention or inhibition of caries development and progression. Information from original scientific full papers or reviews listed in PubMed (search term: fluoride release AND (restorative OR glass-ionomer OR compomer OR polyacid-modified composite resin OR composite OR amalgam)), published from 1980 to 2004, was included in the review. Papers dealing with endodontic or orthodontic topics were not taken into consideration. Clinical studies concerning secondary caries development were only included when performed in split-mouth design with an observation period of at least three years. Fluoride-containing dental materials show clear differences in the fluoride release and uptake characteristics. Short- and long-term fluoride releases from restoratives are related to their matrices, setting mechanisms and fluoride content and depend on several environmental conditions. Fluoride-releasing materials may act as a fluoride reservoir and may increase the fluoride level in saliva, plaque and dental hard tissues. However, clinical studies exhibited conflicting data as to whether or not these materials significantly prevent or inhibit secondary caries and affect the growth of caries-associated bacteria compared to non-fluoridated restoratives. Fluoride release and uptake characteristics depend on the matrices, fillers and fluoride content as well as on the setting mechanisms and environmental conditions of the restoratives. Fluoride-releasing materials, predominantly glass-ionomers and compomers, did show cariostatic properties and may affect bacterial metabolism under simulated cariogenic conditions in vitro. However, it is not proven by prospective clinical studies whether the incidence of secondary caries can be significantly reduced by the fluoride release of

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.

49 CFR 173.163 - Hydrogen fluoride.

Science.gov (United States)

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned in...

FLUORIDE TOXICITY – A HARSH REALITY

OpenAIRE

Bandlapalli Pavani; Mandava Ragini; David Banji; Otilia J F Banji; N Gouri Pratusha

2011-01-01

There are many incidents of fluoride toxicity whether it is acute or chronic. Fluoride toxicity is an environmental hazard which arises from the upper layers of geological crust and is dissolved in water. Prolonged drinking of such water causes chronic fluoride toxicity. Use of fluoride containing compounds for various purposes such as dental products, metal, glass, refrigerator and chemical industries act as a source of fluoride poisoning and increase the risk of toxicity. This review reflec...

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.

Mannosylated thiolated polyethylenimine nanoparticles for the enhanced efficacy of antimonial drug against Leishmaniasis.

Science.gov (United States)

Sarwar, Hafiz S; Ashraf, Sehreen; Akhtar, Sohail; Sohail, Muhammad F; Hussain, Syed Z; Rafay, Muhammad; Yasinzai, Masoom; Hussain, Irshad; Shahnaz, Gul

2018-01-01

Our aim was to inhibit trypanothione reductase (TR) and P-gp efflux pump of Leishmania by the use of thiolated polymers. Thus, increasing the intracellular accumulation and therapeutic effectiveness of antimonial compounds. Mannosylated thiolated chitosan and mannosylated thiolated chitosan-polyethyleneimine graft were synthesized and characterized. Meglumine antimoniate-loaded nanoparticles were prepared and evaluated for TR and P-gp efflux pump inhibition, biocompatibility, macrophage uptake and antileishmanial potential. Thiomers inhibited TR with Ki 2.021. The macrophage uptake was 33.7- and 18.9-fold higher with mannosylated thiolated chitosan-polyethyleneimine graft and mannosylated thiolated chitosan nanoparticles, respectively, as compared with the glucantime. Moreover, the in vitro antileishmanial activity showed 14.41- and 7.4-fold improved IC 50 for M-TCS-g-PEI and M-TCS, respectively as compared with glucantime. These results encouraged the concept that TR and P-gp inhibition by the use of thiomers improves the therapeutic efficacy of antimonial drugs.

Molecular epidemiology and in vitro evidence suggest that Leishmania braziliensis strain helps determine antimony response among American tegumenary leishmaniasis patients.

Science.gov (United States)

Silva, Silvana C; Guimarães, Luiz Henrique; Silva, Juliana A; Magalhães, Viviane; Medina, Lilian; Queiroz, Adriano; Machado, Paulo Roberto L; Schriefer, Albert

2018-02-01

Antimony is the first line drug for treating American tegumentary leishmaniasis (ATL) in Brazil. In this country, Leishmania braziliensis causes at least three distinct forms of disease: localized cutaneous (CL), mucosal (ML) and disseminated leishmaniasis (DL). All forms can be found in Corte de Pedra, Northeast Brazil. ML and DL respond poorly to antimony, in contrast to CL. The L. braziliensis population causing ATL in Corte de Pedra is genetically very diverse, with strains of the parasite associating with the clinical form of leishmaniasis. We tested the hypotheses that antimony refractoriness is associated with L. braziliensis genotypes, and that parasites from ML and DL present greater in vitro resistance to antimony than L. braziliensis from CL. Comparison of geographic coordinates of living sites between antimony responders and non-responders by Cusick and Edward́s test showed that refractoriness and responsiveness to the drug were similarly wide spread in the region (p>0.05). Parasites were then genotyped by sequencing a locus starting at position 425,451 on chromosome 28, which is polymorphic among L. braziliensis of Corte de Pedra. Haplotype CC- in CHR28/425,451 was associated with risk of treatment failure among CL patients (Fisheŕs exact test, p=0.03, odds ratio=4.65). This haplotype could not be found among parasites from ML or DL. Finally, sensitivity to antimony was evaluated exposing L. braziliensis promastigotes to increasing concentrations of meglumine antimoniate in vitro. Parasites from ML and DL were more resistant to antimony at doses of 2mg/100μL and beyond than those isolated from CL (Fisher's exact test, p=0.02 and p=0.004, respectively). The intrinsically lower susceptibility of L. brazliensis from ML and DL to antimony parallels what is observed for patients' responsiveness in the field. This finding reinforces that ML and DL patients would benefit from initiating treatment with drugs currently considered as second line, like

Improved Long-Term Stability of Transparent Conducting Electrodes Based on Double-Laminated Electrosprayed Antimony Tin Oxides and Ag Nanowires

Directory of Open Access Journals (Sweden)

Koo B.-R.

2017-06-01

Full Text Available We fabricated double-laminated antimony tin oxide/Ag nanowire electrodes by spin-coating and electrospraying. Compared to pure Ag nanowire electrodes and single-laminated antimony tin oxide/Ag nanowire electrodes, the double-laminated antimony tin oxide/Ag nanowire electrodes had superior transparent conducting electrode performances with sheet resistance ~19.8 Ω/□ and optical transmittance ~81.9%; this was due to uniform distribution of the connected Ag nanowires because of double lamination of the metallic Ag nanowires without Ag aggregation despite subsequent microwave heating at 250°C. They also exhibited excellent and superior long-term chemical and thermal stabilities and adhesion to substrate because double-laminated antimony tin oxide thin films act as the protective layers between Ag nanowires, blocking Ag atoms penetration.

Speciation analysis of antimony in extracts of size-classified volcanic ash by HPLC-ICP-MS.

Science.gov (United States)

Miravet, R; López-Sánchez, J F; Rubio, R; Smichowski, P; Polla, G

2007-03-01

Although there is concern about the presence of toxic elements and their species in environmental matrices, for example water, sediment, and soil, speciation analysis of volcanic ash has received little attention. Antimony, in particular, an emerging element of environmental concern, has been less studied than other potentially toxic trace elements. In this context, a study was undertaken to assess the presence of inorganic Sb species in ash emitted from the Copahue volcano (Argentina). Antimony species were extracted from size-classified volcanic ash (<36 microm, 35-45 microm, 45-150 microm, and 150-300 microm) by use of 1 mol L(-1) citrate buffer at pH 5. Antimony(III) and (V) in the extracts were separated and quantified by high-performance liquid chromatography combined on-line with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Antimony species concentrations (microg g(-1)) in the four fractions varied from 0.14 to 0.67 for Sb(III) and from 0.02 to 0.03 for Sb(V). The results reveal, for the first time, the occurrence of both inorganic Sb species in the extractable portion of volcanic ash. Sb(III) was always the predominant species.

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

Electrical conductivity of uranium-antimony oxide catalysts

International Nuclear Information System (INIS)

Golunski, S.E.; Nevell, T.G.; Hucknall, D.J.

1985-01-01

The relative ionic and electronic contributions to the electrical conductivity of a uranium-antimony oxide catalyst and of USbO 5 have been determined from measurements of a.c. and d.c. conductance. Under inert atmospheres (390 to 775 K) conduction in the catalyst (predominantly USb 3 O 10 together with small proportions of Sb 2 O 4 and USbO 5 ) is associated with both electronic and effectively charged atomic point defects. Only electronic conduction occurs in USbO 5 . Under oxygen (10 to 70 kPa, 493 to 682 K) both materials are n-type semiconductors at higher temperatures, but at lower temperatures semiconducting behaviour varies with the pressure of oxygen. Heating USbO 5 in oxygen induces an ionic contribution to conductivity. Ionic conduction in the catalyst is eliminated by heating in hydrogen or propene at 470 K but is restored by heating in oxygen. It is suggested that both charged oxygen vacancies and interstitial oxide ions are involved in interactions of gaseous components with uranium-antimony oxides. With alkenes, interstitial oxide ions give rise to the products of selective partial oxidation. (author)

Electrical conductivity of uranium-antimony oxide catalysts

Energy Technology Data Exchange (ETDEWEB)

Golunski, S.E.; Nevell, T.G. (Portsmouth Polytechnic (UK)); Hucknall, D.J. (Southampton Univ. (UK). Dept. of Chemistry)

1985-05-01

The relative ionic and electronic contributions to the electrical conductivity of a uranium-antimony oxide catalyst and of USbO/sub 5/ have been determined from measurements of a.c. and d.c. conductance. Under inert atmospheres (390 to 775 K) conduction in the catalyst (predominantly USb/sub 3/O/sub 10/ together with small proportions of Sb/sub 2/O/sub 4/ and USbO/sub 5/) is associated with both electronic and effectively charged atomic point defects. Only electronic conduction occurs in USbO/sub 5/. Under oxygen (10 to 70 kPa, 493 to 682 K) both materials are n-type semiconductors at higher temperatures, but at lower temperatures semiconducting behaviour varies with the pressure of oxygen. Heating USbO/sub 5/ in oxygen induces an ionic contribution to conductivity. Ionic conduction in the catalyst is eliminated by heating in hydrogen or propene at 470 K but is restored by heating in oxygen. It is suggested that both charged oxygen vacancies and interstitial oxide ions are involved in interactions of gaseous components with uranium-antimony oxides. With alkenes, interstitial oxide ions give rise to the products of selective partial oxidation.

Enhanced electrochemical stability of carbon-coated antimony nanoparticles with sodium alginate binder for sodium-ion batteries

Directory of Open Access Journals (Sweden)

Jianmin Feng

2018-04-01

Full Text Available The poor cycling stability of antimony during a repeated sodium ion insertion and desertion process is the key issue, which leads to an unsatisfactory application as an anode material in a sodium-ion battery. Addressed at this, we report a facile two-step method to coat antimony nanoparticles with an ultrathin carbon layer of few nanometers (denoted Sb@C NPs for sodium-ion battery anode application. This carbon layer could buffer the volume change of antimony in the charge-discharge process and improve the battery cycle performance. Meanwhile, this carbon coating could also enhance the interfacial stability by firmly connecting the sodium alginate binders through its oxygen-rich surface. Benefitted from these advantages, an improved initial discharge capacity (788.5 mA h g−1 and cycling stability capacity (553 mA h g−1 after 50 times cycle have been obtained in a battery using Sb@C NPs as anode materials at 50 mA g−1. Keywords: Sodium-ion battery, Antimony, Sodium alginate, Liquid-phase reduction, Carbon coating

Physiology and toxicity of fluoride

OpenAIRE

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 mineralizat...

Assessment of alternate ion exchange resins for improved antimony removal from the primary heat transport system

Energy Technology Data Exchange (ETDEWEB)

Burany, R.; Suryanarayan, S.; Husain, A. [Kinectrics, Inc., Toronto, ON (Canada)

2015-07-01

Radiation fields around the CANDU heat transport system are a major contributor to worker dose during inspection, maintenance and refurbishment activities. While Co-60 is typically the dominant contributor to radiation fields in CANDU reactors, Sb-124, an activation product of antimony, is also a significant contributor, accounting for 5-20% of the radiation fields. The goal of this research project was to investigate resins for improved removal of antimony under both oxidizing and reducing conditions.Several candidate resins were tested and short-listed through a sequence of iterative testing. The results of the laboratory testing have identified potential candidates for improved antimony removal. Further testing is required to ensure compatibility with existing station resin specifications. (author)

Ultrafast photoinduced structure phase transition in antimony single crystals

NARCIS (Netherlands)

Fausti, Daniele; Misochko, Oleg V.; van Loosdrecht, Paul H. M.

2009-01-01

Picosecond Raman scattering is used to study the photoinduced ultrafast dynamics in Peierls distorted antimony. We find evidence for an ultrafast nonthermal reversible structural phase transition. Most surprisingly, we find evidence that this transition evolves toward a lower symmetry in contrast to

Uptake and Transformation of Methylated and Inorganic Antimony in Plants.

Science.gov (United States)

Ji, Ying; Mestrot, Adrien; Schulin, Rainer; Tandy, Susan

2018-01-01

Used as a hardening agent in lead bullets, antimony (Sb) has become a major contaminant in shooting range soils of some countries including Switzerland. Soil contamination by Sb is also an environmental problem in countries with Sb-mining activities such as China and Bolivia. Because of its toxicity and relatively high mobility, there is concern over the risk of Sb transfer from contaminated soils into plants, and thus into the food chain. In particular there is very little information on the environmental behavior of methylated antimony, which can be produced by microbial biomethylation of inorganic Sb in contaminated soils. Using a new extraction and high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method, we investigated antimony speciation in roots and shoots of wheat, fescue, rye, and ryegrass plants exposed to trimethyl antimony(V) (TMSb), antimonite (Sb(III)), and antimonate (Sb(V)) in hydroponics. The total root Sb concentrations followed the order Sb(III) treatment > Sb(V) treatment > TMSb treatment, except for fescue. Shoot Sb concentrations, however, did not differ among the three treatments. In the Sb(V) treatment small quantities of TMSb were found in the roots, whereas no TMSb was detected in the roots of Sb(III)-treated plants. In contrast, similar concentrations of TMSb were found in the shoots in both inorganic Sb treatments. The results indicate that biomethylation of Sb may occur in plants. In the TMSb treatment TMSb was the major Sb species, but the two inorganic Sb species were also found both in shoots and roots along with some unknown Sb species, suggesting that also TMSb demethylation may occur within plant tissues. The results furthermore indicate that methylated Sb is more mobile in plants than inorganic Sb species. Knowledge about this is important in risk assessments of Sb-contaminated sites, as methylation may render Sb more toxic than inorganic Sb, as it is known for arsenic (As).

The Effect of Calcium Pre-Rinse on Salivary Fluoride After 900 ppm Fluoride Mouthwash: A Randomized Clinical Trial

Directory of Open Access Journals (Sweden)

Nahid Ramazani

2013-01-01

Full Text Available Objective: Calcium fluoride deposit during fluoride application. Uptake and retention of fluoride by saliva depends generally on the concentration of calcium. In this study, the ef-fect of calcium pre-rinse on salivary fluoride concentration after a 900 ppm fluoride mouthwash was investigated.Materials and Methods: This cross-over double-blind randomized clinical trial was con-ducted in a girls' dormitory in Zahedan University of Medical Sciences, southeast Iran. In this study, 42 female dental students were chosen using simple randomization. During the first phase, 21 subjects (group A used fluoride rinse (F regimen and the remaining (group B used calcium pre-rinse followed immediately by fluoride rinse (Ca + F regi-men. In the second phase, participants rinsed using the mouthwashes not previously used. Prior to each phase prophylaxis was performed and no fluoridated product was used dur-ing a two-week interval between the phases. Salivary samples were taken immediately be-fore (baseline, 1 and 12 hours after rinsing. The salivary fluoride concentration was de-termined using fluoride sensitive electrode. Repeated measures ANOVA was used for sta-tistical analysis and the significance level was set at P<0.05.Results: There was significant difference between fluoride concentrations at different time points (P< 0.001. Significant differences were observed when the different time points of two regimens were examined. In contrast to this, the baseline before using F regimen and the baseline before using Ca + F regimen did not show any significance (P= 0.070.Conclusion: Pre-rinsing with calcium before fluoride is recommended because of signifi-cant increases in salivary fluoride concentration.

Review of the prevalence and causes of antimony compounds resistance in different societies review article

Directory of Open Access Journals (Sweden)

Fariba Jaffary

2017-09-01

Full Text Available Cutaneous leishmaniasis (CL is an endemic parasitic disease of major health impact in many parts of the world and is caused by several species of the protozoan parasite Leishmania. Antimonial compounds (i.e glucantime and pentostam are the first-line treatment for cutaneous leishmaniasis with emerging drug resistance as a problem. The control of Leishmania is further complicated by the emergence of drug-resistant parasites. In the clinical settings, resistance to SbV containing drugs is now well established and it was found to occur in South America, Europe, the Middle East and most notably in India. Clinical resistance to organic pentavalent antimonials, in the form of sodium stibogluconate (pentostam or N-methylglucamine antimoniate (glucantime, has long been recognized. However, it is unknown whether the clinical failure of chemotherapy is attributable to the development of drug resistance mechanisms in the parasite or to a variety of host factors that might also contribute to low drug response. Reported rate of drug-resistance to antimonial compounds in Iran varies from 9.4% to 94.2% and there is not any comprehensive study on this issue. Indeed, in the endemic region treatment with SbV fails in more cases; thus, in general patients infected with resistant parasites are unresponsive although exceptions have been reported. This article aims to review the mechanisms of drug resistance to these compounds. The main resistance factors include genetical, enzymatic, intracellular (such as apoptosis and cytoskeleton changes and resistance proteins. Also, mechanisms related to drug transport and intracellular activation are discussed. Various methods of drug resistance detection such as culture and molecular methods (i.e polymerase chain reaction are reviewed. Although the exact mechanism of action glucantime is not clear, it seems that protein and gene factors involved in cellular drug entry are the main causes of drug resistance. Cross

Fluoride resistance in Streptococcus mutans

NARCIS (Netherlands)

Liao, Ying

2017-01-01

Fluoride has been used as the most effective anti-caries agent for over five decades. It functions not only on the dental hard tissues, but also as an antimicrobial agent. It is known that oral bacteria are able to develop resistance to fluoride, which may affect the effectiveness of fluoride in

Molecular mechanisms of fluoride toxicity.

Science.gov (United States)

Barbier, Olivier; Arreola-Mendoza, Laura; Del Razo, Luz María

2010-11-05

Halfway through the twentieth century, fluoride piqued the interest of toxicologists due to its deleterious effects at high concentrations in human populations suffering from fluorosis and in in vivo experimental models. Until the 1990s, the toxicity of fluoride was largely ignored due to its "good reputation" for preventing caries via topical application and in dental toothpastes. However, in the last decade, interest in its undesirable effects has resurfaced due to the awareness that this element interacts with cellular systems even at low doses. In recent years, several investigations demonstrated that fluoride can induce oxidative stress and modulate intracellular redox homeostasis, lipid peroxidation and protein carbonyl content, as well as alter gene expression and cause apoptosis. Genes modulated by fluoride include those related to the stress response, metabolic enzymes, the cell cycle, cell-cell communications and signal transduction. The primary purpose of this review is to examine recent findings from our group and others that focus on the molecular mechanisms of the action of inorganic fluoride in several cellular processes with respect to potential physiological and toxicological implications. This review presents an overview of the current research on the molecular aspects of fluoride exposure with emphasis on biological targets and their possible mechanisms of involvement in fluoride cytotoxicity. The goal of this review is to enhance understanding of the mechanisms by which fluoride affects cells, with an emphasis on tissue-specific events in humans. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

First-principles study of antimony doping effects on the iron-based superconductor CaFe(SbxAs1−x)2

International Nuclear Information System (INIS)

Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; Kuroki, Kazuhiko

2015-01-01

We study antimony doping effects on the iron-based superconductor CaFe(Sb x As 1−x ) 2 by using the first-principles calculation. The calculations reveal that the substitution of a doped antimony atom into As of the chainlike As layers is more stable than that into FeAs layers. This prediction can be checked by experiments. Our results suggest that doping homologous elements into the chainlike As layers, which only exist in the novel 112 system, is responsible for rising up the critical temperature. We discuss antimony doping effects on the electronic structure. It is found that the calculated band structures with and without the antimony doping are similar to each other within our framework. (author)

An investigation of inorganic antimony species and antimony associated with soil humic acid molar mass fractions in contaminated soils

International Nuclear Information System (INIS)

Steely, Sarah; Amarasiriwardena, Dulasiri; Xing Baoshan

2007-01-01

The presence of antimony compounds is often suspected in the soil of apple orchards contaminated with lead arsenate pesticide and in the soil of shooting ranges. Nitric acid (1 M) extractable Sb from the shooting range (8300 μg kg -1 ) and the apple orchard (69 μg kg -1 ) had considerably higher surface Sb levels than the control site ( -1 ), and Sb was confined to the top ∼30 cm soil layer. Sb(V) was the principal species in the shooting range and the apple orchard surface soils. Size exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS) analysis of humic acids isolated from the two contaminated soils demonstrated that Sb has complexed to humic acid molar mass fractions. The results also indicate that humic acids have the ability to arrest the mobility of Sb through soils and would be beneficial in converting Sb(III) to a less toxic species, Sb(V), in contaminated areas. - The soil surface and depth distribution Sb(V) and Sb(III) species in a contaminated apple orchard and a shooting range, and the effect soil humic acids on inorganic antimony species is reported

EVALUAION OF NEUTRON DATA FOR NATURAL ANTIMONY

Institute of Scientific and Technical Information of China (English)

1991-01-01

<正> The complete neutron nuclear data of natural antimony have been per-formed for CENDL-2 in neutron energy range from 10-5eV to 20 MeV.Someof the data have been calculated by means of theoretical model.A good agree-ment was obtained with measured values.The recommended data were com-pared with the evaluations of JENDL-3 and ENDF/B-6.

Fluoride-releasing restorative materials and secondary caries.

Science.gov (United States)

Hicks, John; Garcia-Godoy, Franklin; Donly, Kevin; Flaitz, Catherine

2003-03-01

Secondary caries is responsible for 60 percent of all replacement restorations in the typical dental practice. Risk factors for secondary caries are similar to those for primary caries development. Unfortunately, it is not possible to accurately predict which patients are at risk for restoration failure. During the past several decades, fluoride-releasing dental materials have become a part of the dentist's armamentarium. Considerable fluoride is released during the setting reaction and for periods up to eight years following restoration placement. This released fluoride is readily taken up by the cavosurface tooth structure, as well as the enamel and root surfaces adjacent to the restoration. Resistance against caries along the cavosurface and the adjacent smooth surface has been shown in both in vitro and in vivo studies. Fluoride-releasing dental materials provide for improved resistance against primary and secondary caries in coronal and root surfaces. Plaque and salivary fluoride levels are elevated to a level that facilitates remineralization. In addition, the fluoride released to dental plaque adversely affects the growth of lactobacilli and mutans streptococci by interference with bacterial enzyme systems. Fluoride recharging of these dental materials is readily achieved with fluoridated toothpastes, fluoride mouthrinses, and other sources of topical fluoride. This allows fluoride-releasing dental materials to act as intraoral fluoride reservoirs. The improvement in the properties of dental materials with the ability to release fluoride has improved dramatically in the past decade, and it is anticipated that in the near future the vast majority of restorative procedures will employ fluoride-releasing dental materials as bonding agents, cavity liners, luting agents, adhesives for orthodontic brackets, and definitive restoratives.

Antimony Adsorption from Zarshouran Gold Mineral Processing Plant Wastewater by Nano Zero Valent Iron Coated on Bentonite

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nader nosrati

2015-03-01

Full Text Available The effluent from Zarshouran gold mineral processing plant contains high quantities of arsenic, antimony, mercury, and bismuth. These metals and metalloids are soluble in water and very toxic when they enter the environment. Their solubility in water causes the polluted area to extend beyond their point of origin. In this article, different methods of antimony removal from water and wastewater were reviewed and the zero-valent iron nanoparticles coated on Bentonite were selected as an effective and low cost material for removing antimony from wastewater. For the purposes of this study, zero-valent iron nanoparticles of 40-100 nanometers in size were synthesized by dropwise addition of sodium borohydride solution to an Iron (III aqueous solution at  ambient temperature and mixed with nitrogen gas. To avoid particle agglomeration and to enhance the product’s environmentally safe application, the  nanoparticles were coated on Bentonite and characterized by SEM/EDAX and BET. The experiments were carried out by intense mixing of the adsorbent with 10ml of real/synthtic wastewater samples in 20ml bottles.  The effects of pH, contact time, temperature, and adsorbent dosage on antimony removal efficiency were investigated under intense mixing using a magnetic mixer. Finally, the effluents were filtered upon completion of the experiments and used for atomic adsorption analysis. The results of the experiments showed that the adsorption isotherms of the synthesized nanoparticles obeyed the Langmuir and Freundlich models. The experiments carried out on real samples showed that antimony adsorption capacity for B-nZVI was 2.6 mg/g of the adsorbent and that the highest antimony removal efficiency was 99.56%.

Sequestration of Antimony on Calcite Observed by Time-Resolved Nanoscale Imaging.

Science.gov (United States)

Renard, François; Putnis, Christine V; Montes-Hernandez, German; King, Helen E; Breedveld, Gijs D; Okkenhaug, Gudny

2018-01-02

Antimony, which has damaging effects on the human body and the ecosystem, can be released into soils, ground-, and surface waters either from ore minerals that weather in near surface environments, or due to anthropogenic releases from waste rich in antimony, a component used in batteries, electronics, ammunitions, plastics, and many other industrial applications. Here, we show that dissolved Sb can interact with calcite, a widespread carbonate mineral, through a coupled dissolution-precipitation mechanism. The process is imaged in situ, at room temperature, at the nanometer scale by using an atomic force microscope equipped with a flow-through cell. Time-resolved imaging allowed following the coupled process of calcite dissolution, nucleation of precipitates at the calcite surface and growth of these precipitates. Sb(V) forms a precipitate, whereas Sb(III) needs to be oxidized to Sb(V) before being incorporated in the new phase. Scanning-electron microscopy and Raman spectroscopy allowed identification of the precipitates as two different calcium-antimony phases (Ca 2 Sb 2 O 7 ). This coupled dissolution-precipitation process that occurs in a boundary layer at the calcite surface can sequester Sb as a solid phase on calcite, which has environmental implications as it may reduce the mobility of this hazardous compound in soils and groundwaters.

Interplay of single particle and collective excitations in antimony nuclei

International Nuclear Information System (INIS)

Stan-Sion, C.

1987-01-01

The antimony nuclei are considered classical examples for coexisting spherical and well-deformed structures. The electromagnetic moment measurements presented in this paper provide direct evidence for shape coexistence. 8 refs., 3 figs. (M.F.W.)

Organic ligand-induced dissolution kinetics of antimony trioxide.

Science.gov (United States)

Hu, Xingyun; He, Mengchang

2017-06-01

The influence of low-molecular-weight dissolved organic matter (LMWDOM) on the dissolution rate of Sb 2 O 3 was investigated. Some representative LMWDOMs with carboxyl, hydroxyl, hydrosulfuryl and amidogen groups occurring naturally in the solution were chosen, namely oxalic acid, citric acid, tartaric acid, EDTA, salicylic acid, phthalandione, glycine, thiolactic acid, xylitol, glucose and catechol. These LMWDOMs were dissolved in inert buffers at pH=3.7, 6.6 and 8.6 and added to powdered Sb 2 O 3 in a stirred, thermostatted reactor (25°C). The addition of EDTA, tartaric acid, thiolactic acid, citric acid and oxalic acid solutions at pH3.7 and catechol at pH8.6 increased the rate of release of antimony. In the 10mmol/L thiolactic acid solution, up to 97% by mass of the antimony was released after 120min reaction. There was no effect on the dissolution of Sb 2 O 3 for the other ligands. A weak correlation between dissolution rate with the dissociation constant of ligands and the stability of the dissolved complex was also found. All the results showed that the extent of the promoting effect of ligands on the dissolution of Sb 2 O 3 was not determined by the stability of the dissolved complex, but by the dissociation constant of ligands and detachment rate of surface chelates from the mineral surface. This study can not only help in further understanding the effect of individual low-molecular-weight organic ligands, but also provides a reference to deduce the effect of natural organic matters with oxygen-bearing functional groups on the dissolution of antimony oxide minerals. Copyright © 2016. Published by Elsevier B.V.

Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: Arsenic, manganese, fluoride, iron, and uranium

Energy Technology Data Exchange (ETDEWEB)

Bacquart, Thomas [Better Life Laboratories, Calais, VT (United States); Frisbie, Seth [Better Life Laboratories, Calais, VT (United States); Department of Chemistry and Biochemistry, Norwich University, Northfield, VT (United States); Mitchell, Erika [Better Life Laboratories, Calais, VT (United States); Grigg, Laurie [Department of Earth and Environmental Science, Norwich University, Northfield, VT (United States); Cole, Christopher [Department of Chemistry and Biochemistry, Norwich University, Northfield, VT (United States); Small, Colleen [Vermont Department of Health Laboratory, Burlington, VT (United States); Sarkar, Bibudhendra, E-mail: bsarkar@sickkids.ca [Department of Molecular Structure and Function, The Research Institute of The Hospital for Sick Children, University of Toronto, Toronto, Ontario (Canada); Department of Biochemistry, University of Toronto, Toronto, Ontario (Canada)

2015-06-01

In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic

Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: Arsenic, manganese, fluoride, iron, and uranium

International Nuclear Information System (INIS)

Bacquart, Thomas; Frisbie, Seth; Mitchell, Erika; Grigg, Laurie; Cole, Christopher; Small, Colleen; Sarkar, Bibudhendra

2015-01-01

In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic

Thermal decomposition kinetics of antimony oxychloride in air

Institute of Scientific and Technical Information of China (English)

阳卫军; 唐谟堂; 金胜明

2002-01-01

The DTA and XRD techniques were employed to study thermal decomposition mechanism of antimony oxychloride SbOCl in the air. The thermal decomposition reaction occurs in four steps, and the former three steps as: SbOCl(s)→Sb4O5Cl2(s)+SbCl3(g)→Sb8O11Cl2(s)+SbCl3(g)→Sb2O3(s)+SbCl3(g). The forth step is the oxidation of Sb2O3 by air, Sb2O3(s)+O2→Sb2O4(s). The activation energy and the order of the thermal decomposition reaction of antimony oxychloride in three steps presented in DTA curves were calculated according to Kinssinger methods from DTA curves. The values of activation energy and the order are respectively 91.97kJ/mol, 0.73 in the first step, 131.14kJ/mol, 0.63 in the second step and 146.94kJ/mol, 1.58 in the third step.

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

Influence of the method of fluoride administration on toxicity and fluoride concentrations in Japanese quail

Science.gov (United States)

Fleming, W.J.; Schuler, C.A.

1988-01-01

Young Japanese quail (Coturnix japonica) were administered NaF for 16 d either in their diet or by esophageal intubation. Based on the total fluoride ion (Emg F-) intake over the l6-d experimental period, fluoride administered by intubation was at least six times more toxic than that fed in the diet. Dietary concentrations of 1,000 ppm F- (Emg F- for 16 d = approx. 144) produced no mortality, whereas intubated doses produced 73% or greater mortality in all groups administered 54 mg F- /kg/d or more (Emg F- for 16 d _ approx. 23 mg). GraphIc companson of the regression of log F- ppm in femurs/mg F- intake showed that fluoride levels in the femurs of quail administered fluoride by intubation were higher than in those administered fluoride in the diet.

Co-doping with antimony to control phosphorous diffusion in germanium

KAUST Repository

Tahini, H. A.; Chroneos, Alexander; Grimes, R. W.; Schwingenschlö gl, Udo

2013-01-01

donor co-doping on the migration activation energies of vacancy-mediated diffusion processes. The migration energy barriers for phosphorous and antimony were found to be increased significantly when larger clusters involving two donor atoms and a vacancy

Dismantling and chemical characterization of spent Peltier thermoelectric devices for antimony, bismuth and tellurium recovery.

Science.gov (United States)

Balva, Maxime; Legeai, Sophie; Garoux, Laetitia; Leclerc, Nathalie; Meux, Eric

2017-04-01

Major uses of thermoelectricity concern refrigeration purposes, using Peltier devices, mainly composed of antimony, bismuth and tellurium. Antimony was identified as a critical raw material by EU and resources of bismuth and tellurium are not inexhaustible, so it is necessary to imagine the recycling of thermoelectric devices. That for, a complete characterization is needed, which is the aim of this work. Peltier devices were manually dismantled in three parts: the thermoelectric legs, the alumina plates on which remain the electrical contacts and the silicone paste used to connect the plates. The characterization was performed using five Peltier devices. It includes mass balances of the components, X-ray diffraction analysis of the thermoelectric legs and elemental analysis of each part of the device. It appears that alumina represents 45% of a Peltier device in weight. The electrical contacts are mainly composed of copper and tin, and the thermoelectric legs of bismuth, tellurium and antimony. Thermoelectric legs appear to be Se-doped Bi 2 Te 3 and (Bi 0,5 Sb 1,5 )Te 3 for n type and p type semiconductors, respectively. This work shows that Peltier devices can be considered as a copper ore and that thermoelectric legs contain high amounts of bismuth, tellurium and antimony compared to their traditional resources.

Sorption-desorption of antimony species onto calcined hydrotalcite: Surface structure and control of competitive anions.

Science.gov (United States)

Constantino, Leonel Vinicius; Quirino, Juliana Nunes; Abrão, Taufik; Parreira, Paulo Sérgio; Urbano, Alexandre; Santos, Maria Josefa

2018-02-15

Calcined hydrotalcite can be applied to remove anionic contaminants from aqueous systems such as antimony species due to its great anion exchange capacity and high surface area. Hence, this study evaluated antimonite and antimonate sorption-desorption processes onto calcined hydrotalcite in the presence of nitrate, sulfate and phosphate. Sorption and desorption experiments of antimonite and antimonate were carried out in batch equilibrium and the post-sorption solids were analyzed by X-ray fluorescence (EDXRF). Sorption data were better fitted by dual-mode Langmuir-Freundlich model (R 2 >0.99) and desorption data by Langmuir model. High maximum sorption capacities were found for the calcined hydrotalcite, ranging from 617 to 790meqkg -1 . The competing anions strongly affected the antimony sorption. EDXRF analysis and mathematical modelling showed that sulfate and phosphate presented higher effect on antimonite and antimonate sorption, respectively. High values for sorption efficiency (SE=99%) and sorption capacity were attributed to the sorbent small particles and the large surface area. Positive hysteresis indexes and low mobilization factors (MF>3%) suggest very low desorption capacity to antimony species from LDH. These calcined hydrotalcite characteristics are desirable for sorption of antimony species from aqueous solutions. Copyright © 2017. Published by Elsevier B.V.

Identification of Potential Biomarkers for Antimony Susceptibility ...

Indian Academy of Sciences (India)

Identification of Potential Biomarkers for Antimony Susceptibility/Resistance in L. donovani Rentala Madhubala School of Life Sciences Jawaharlal Nehru University New Delhi, India · Slide 2 · Slide 3 · Slide 4 · Slide 5 · Slide 6 · Slide 7 · Slide 8 · Slide 9 · Slide 10 · Slide 11 · Slide 12 · Slide 13 · Slide 14 · Slide 15 · Slide 16.

Application of Titanium Compounds to Reduce Fluoride Ion in Water Resources with High Fluoride Ion Contents

Directory of Open Access Journals (Sweden)

Fariborz Riahi

2005-06-01

Full Text Available The present work describes studies on the sorption of fluoride ions from water by titanium compounds used in water treatment to reduce fluoride content in water resources. There are different methods of reducing fluoride ion in water, each associated with specific problems such as secondary contamination, environmental contamination, high costs, or the need for primary and secondary treatment. In this study, application of titanium sulfate and Metatitanic acid produced from titanium ore concentrate (ileminite is investigated in the removal of fluoride ion and the possibility of complete purification of fluorine containing wastewater is examined to determine the optimal conditions. Metatitanic acid has a great sorption property for fluoride ion. Also titanium sulfate is a suitable and more effective material for this purpose. Efficiency of this material in reducing fluoride ion content is 99.9% and it is possible to refresh sorbet material for reuse without problems arising from Ti+4 ion contamination.

Toxic effects of fluoride on organisms.

Science.gov (United States)

Zuo, Huan; Chen, Liang; Kong, Ming; Qiu, Lipeng; Lü, Peng; Wu, Peng; Yang, Yanhua; Chen, Keping

2018-04-01

Accumulation of excess fluoride in the environment poses serious health risks to plants, animals, and humans. This endangers human health, affects organism growth and development, and negatively impacts the food chain, thereby affecting ecological balance. In recent years, numerous studies focused on the molecular mechanisms associated with fluoride toxicity. These studies have demonstrated that fluoride can induce oxidative stress, regulate intracellular redox homeostasis, and lead to mitochondrial damage, endoplasmic reticulum stress and alter gene expression. This paper reviews the present research on the potential adverse effects of overdose fluoride on various organisms and aims to improve our understanding of fluoride toxicity. Copyright © 2018 Elsevier Inc. All rights reserved.

Magnetic interactions through fluoride

DEFF Research Database (Denmark)

Pedersen, Kasper Steen; Sigrist, Marc; Weihe, Høgni

2014-01-01

support the parameter values and resolve |E| ≈ 0.04 cm(-1). The exchange coupling constant (J) is 1 order of magnitude smaller than that found in comparable systems with linear oxide bridging but comparable to typical magnitudes through cyanide, thus underlining the potential of fluoride complexes......The nature of the magnetic interaction through fluoride in a simple, dinuclear manganese(III) complex (1), bridged by a single fluoride ion in a perfectly linear fashion, is established by experiment and density functional theory. The magnitude of the antiferromagnetic exchange interaction...

Application of KWU antimony removal process at Gentilly-2

International Nuclear Information System (INIS)

Dundar, Y.; Odar, S.; Streit, K.; Allsop, H.; Guzonas, D.

1996-09-01

This paper describes the work performed to adapt the KWU PWR antimony removal process to CANDU plant conditions, and the application of the process at the Hydro Quebec unit, Gentilly-2. The results of the application will be presented and the 'lessons learned' will be discussed in detail. (author)

Differential pulse polarographic determination of trace antimony in standard biological samples after preconcentration using 2-nitroso-1-naphthol-4-sulfonic acid

International Nuclear Information System (INIS)

Taher, M. A.

2003-01-01

A highly selective, rapid and economical differential polarographic method has been developed for the determination of trace amounts of antimony in various standard alloys and biological samples after of its 2-naphthol-4 sulfonic acid tetradecyl dimethylbenzylammonium chloride on microcrystalline naphthalene in the ph range of 7.5-11.0. After filtration, the solid mass is shaken with 8-10 ml of 1 M hydrochloric acid (with preconcentration factor of 10) and antimony is determined by differential pulse polarography. Antimony can alternatively be quantitatively absorbed on 2-nitroso-1-naphthol-4-sulfonic acid tetradecyl dimethylbenzylammonium-naphthalene absorbed packed in a column (with preconcentration factor of 30) and determined similarly. In this case, 1.5 μg of antimony can be concentrated in a column from 300 ml of aqueous sample, where its concentration is as low as 5 ng/ml. Characterization of the electro active process included an examination of the degree of reversibility. The results show that the irreversibility of antimony. Various parameters such as the effect of ph, volume of aqueous phase, HCl concentration, reagent concentration, naphthalene concentration, shaking time and interference of a number of metal ions on the determination of antimony have been studied in detail to optimize the conditions for determination in standard alloys and standard biological samples

[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)

Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

Directory of Open Access Journals (Sweden)

Richard Sauerheber

2013-01-01

Full Text Available The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings.

Physiologic conditions affect toxicity of ingested industrial fluoride.

Science.gov (United States)

Sauerheber, Richard

2013-01-01

The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings.

The Effect of Adding Antimony Trioxide (Sb2O3 ‎On A.C Electrical Properties of (PVA-PEG Films

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Akeel Shakir Alkelaby

2017-12-01

Full Text Available In this work, many samples have been prepared by adding Antimony Trioxide (Sb2O3 to the polyvinyl alcohol-poly ethylene glycol (PVA-PEG. The effect of the Sb2O3 added as a filler with different weight percentages on the A.C electrical properties have been investigated. The samples were prepared as films by solution cast technique. The experimental results of the A.C electrical properties show that the dielectric constant increase with the increasing frequency of applied electrical field and concentration of the Antimony Trioxide. Dielectric loss decrease with the increasing the frequency, while it increases with the increase of the concentration of the Antimony Trioxide. The A.C electrical conductivity increase with increasing the Antimony Trioxide contain and frequency for the composition.

One-Step Extraction of Antimony in Low Temperature from Stibnite Concentrate Using Iron Oxide as Sulfur-Fixing Agent

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Yun Li

2016-07-01

Full Text Available A new process for one-step extraction of antimony in low temperature from stibnite concentrate by reductive sulfur-fixation smelting in sodium molten salt, using iron oxide as sulfur-fixing agent, was presented. The influences of molten salt addition and composition, ferric oxide dosage, smelting temperature and duration on extraction efficiency of antimony were investigated in details, respectively. The optimum conditions were determined as follows: 1.0 time stoichiometric requirement (α of mixed sodium salt (αsalt = 1.0, WNaCl:Wsalt = 40%, αFe2O3 = 1.0, Wcoke:Wstibnite = 40%, where W represents weight, smelting at 850 °C (1123 K for 60 min. Under the optimum conditions, the direct recovery rate of antimony can reach 91.48%, and crude antimony with a purity of 96.00% has been achieved. 95.31% of sulfur is fixed in form of FeS in the presence of iron oxide. Meanwhile, precious metals contained in stibnite concentrate are enriched and recovered comprehensively in crude antimony. In comparison to traditional antimony pyrometallurgical process, the smelting temperature of present process is reduced from 1150–1200 °C (1423–1473 K to 850–900 °C (1123–1173 K. Sulfur obtained in stibnite is fixed in FeS which avoids SO2 emission owing to the sulfur-fixing agent. Sodium salt can be regenerated and recycled in smelting system when the molten slag is operated to filter solid residue. The solid residue is subjected to mineral dressing operation to obtain iron sulfide concentrate which can be sold directly or roasted to regenerate into iron oxide.

Potential fluoride toxicity from oral medicaments: A review.

Science.gov (United States)

Ullah, Rizwan; Zafar, Muhammad Sohail; Shahani, Nazish

2017-08-01

The beneficial effects of fluoride on human oral health are well studied. There are numerous studies demonstrating that a small amount of fluoride delivered to the oral cavity decreases the prevalence of dental decay and results in stronger teeth and bones. However, ingestion of fluoride more than the recommended limit leads to toxicity and adverse effects. In order to update our understanding of fluoride and its potential toxicity, we have described the mechanisms of fluoride metabolism, toxic effects, and management of fluoride toxicity. The main aim of this review is to highlight the potential adverse effects of fluoride overdose and poorly understood toxicity. In addition, the related clinical significance of fluoride overdose and toxicity has been discussed.

Effects of hydrogen fluoride on plants

Energy Technology Data Exchange (ETDEWEB)

Yamazoe, F

1970-07-15

Symptoms of fluorosis in plants are chlorotic markings around the tip or edges of young leaves. Examples of damage to plants and livestock by fluorides are listed, including the retarded growth of silkworms fed on mulberry leaves polluted by more than 30 ppm fluorides. Plants can be classified into six groups according to their resistance to hydrogen fluoride. Threshold values of the fluoride concentration range from 5-10 ppb for the plants. Gladiolus is normally employed as a plant indicator for hydrogen fluoride and silkworms as indicator insects. The relationship between plant damage by fluorides and exposure time, density, soil, fertilizer, meteorology and location are examined. Several preventive measures are listed, including the spraying of water or lime on plant leaves. It is concluded that the establishment of an environmental standard is difficult because of the extremely high sensitivity of the plants to the gas. 8 references.

Studies on optical properties of antimony doped SnO{sub 2} films

Energy Technology Data Exchange (ETDEWEB)

Gürakar, Sibel, E-mail: sgurakar@eng.ankara.edu.tr; Serin, Tülay, E-mail: serin@eng.ankara.edu.tr; Serin, Necmi, E-mail: nserin@eng.ankara.edu.tr

2015-10-15

Highlights: • Antimony doped tin oxide thin films were grown by spray method on glass substrates. • The antimony doping was varied from 0 to 4 at%. • The structural properties of the films were investigated by X-ray diffraction method. • A simple analysis according to Swanepoel's method was applied to derive the real and imaginary parts of the complex index of refraction plus film thickness. • The dispersion of refractive index was investigated in terms of the single-oscillator Wemple and DiDomenico model to determine the optical parameters. - Abstract: Antimony doped tin oxide thin films were grown by spray method on microscope glass substrates. The antimony doping was varied from 0 to 4 at%. The structural properties of the films were investigated by X-ray diffraction method. The optical transmittances of thin films were measured with UV-Vis-NIR spectrometer in the 300–2000 nm wavelength range. A simple analysis according to Swanepoel's method was applied to derive the real and imaginary parts of the complex index of refraction plus film thickness. The dispersion of refractive index was investigated in terms of the single-oscillator Wemple and DiDomenico model and the important oscillating parameters such as the dispersion energy E{sub d}, the oscillation energy E{sub o}, the high frequency dielectric constant ε{sub ∞} were determined. The analysis of the refractive index has been carried out to calculate the lattice dielectric constant ε{sub L} and the ratio of carrier concentration to the effective mass N/m*. The real and imaginary parts of the electronic dielectric constant and optical conductivity were analyzed. The optical band gap, E{sub g} values of the films were obtained from the spectral dependence of the absorption coefficient, using the Tauc relation.

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.

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

OpenAIRE

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

2013-01-01

Although fluoride is plentiful in the environment and is commonly used at high concentrations in oral hygiene products, little has been known about how biological systems overcome the toxic effects of this anion. We demonstrate that a protein called FEX in many fungi is essential for cell survival in the presence of high fluoride concentrations. The protein is required for the rapid expulsion of cytoplasmic fluoride, indicating that many eukaryotic species that carry FEX genes likely avoid fl...

Gramicidin D enhances the antibacterial activity of fluoride

OpenAIRE

Nelson, James W.; Zhou, Zhiyuan; Breaker, Ronald R.

2014-01-01

Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in B. subtilis and that the antibacterial activity of this compound...

40 CFR 721.1930 - Butanoic acid, antimony (3=) salt.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Butanoic acid, antimony (3=) salt. 721.1930 Section 721.1930 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.1930 Butanoic acid,...

Accumulation of fluoride by plants and vegetables

International Nuclear Information System (INIS)

Njenga, L.W.; Kariuki, D.N.

1994-01-01

Fluoride in plant and vegetable samples has been determined using ion selective electrode. The analysis was carried out after ashing the sample on an open flame, adding perchloric acid and allowing the hydrogen fluoride to diffuse into sodium hydroxide layer.The results obtained show that kale and pumpkins can accumulate more than ten times their normal values of fluoride while plants were found to accumulate upto 100μg/g fluoride when exposed to highlevels of fluoride in water or soil. (author)

Highly active and stable Pt electrocatalysts promoted by antimony-doped SnO2 supports for oxygen reduction reactions

DEFF Research Database (Denmark)

Yin, Min; Xu, Junyuan; Li, Qingfeng

2014-01-01

Alternative composite supports for platinum catalysts were synthesized from antimony doped tin dioxide (ATO) nanoparticles. In the range of the antimony content from 0 to 11mol%, the highest electrical conductivity of 1.1Scm-1 at 130°C was obtained for the 5mol% Sb ATO, from which composite...

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

Gramicidin D enhances the antibacterial activity of fluoride.

Science.gov (United States)

Nelson, James W; Zhou, Zhiyuan; Breaker, Ronald R

2014-07-01

Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in Bacillus subtilis and that the antibacterial activity of this compound is potentiated by fluoride. Polymyxin B, another membrane-targeting antibiotic with a different mechanism of action, shows no such improvement. These results, along with previous findings, indicate that certain compounds that destabilize bacterial cell envelopes can enhance the toxicity of fluoride. Copyright © 2014 Elsevier Ltd. All rights reserved.

Potential fluoride toxicity from oral medicaments: A review

Directory of Open Access Journals (Sweden)

Rizwan Ullah

2017-08-01

Full Text Available The beneficial effects of fluoride on human oral health are well studied. There are numerous studies demonstrating that a small amount of fluoride delivered to the oral cavity decreases the prevalence of dental decay and results in stronger teeth and bones. However, ingestion of fluoride more than the recommended limit leads to toxicity and adverse effects. In order to update our understanding of fluoride and its potential toxicity, we have described the mechanisms of fluoride metabolism, toxic effects, and management of fluoride toxicity. The main aim of this review is to highlight the potential adverse effects of fluoride overdose and poorly understood toxicity. In addition, the related clinical significance of fluoride overdose and toxicity has been discussed.

Growth of fluoride treated Kalanchoe pinnata plants

Energy Technology Data Exchange (ETDEWEB)

Johnson, H N; Applegate, H G

1962-01-01

Kalanchoe pinnata plants can absorb fluoride through roots. The absorption is related to the amount of fluoride applied to the soil. There appeared to be a relationship between the amount of fluoride adsorbed and the subsequent growth of the plants. Plants which adsorbed the largest amounts of fluoride had the greatest increase in growth.

Well Waters Fluoride in Enugu, Nigeria

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ISI Ogbu

2012-03-01

Full Text Available Abnormal fluoride levels in drinking water have been associated with adverse health effects. To determine the fluoride content of well waters in Enugu, southeastern Nigeria, water samples from 50 artisan wells chosen by multistage sampling procedure from the 5 zones of Enugu municipality were analyzed in duplicates for their fluoride content. The zonal mean values were 0.60, 0.70, 0.62, 0.62, and 0.63 mg/L for Abakpa Nike, Achara Layout, Obiagu/ Ogui, Trans Ekulu and Uwani, respectively (p<0.05. The mean value for the whole city was 0.63 mg/L. Although, the mean level of fluoride recorded in this study is currently within safe limits (1.5 mg/L, WHO 2011, it is important to monitor continuously the fluoride content of well waters in the municipality in view of the increasing industrial activities going on in the city and heavy reliance on well water for domestic purposes and the widespread use of consumer products containing fluoride.

Enhancing the antimony sorption properties of nano titania-chitosan beads using epichlorohydrin as the crosslinker.

Science.gov (United States)

Nishad, Padala Abdul; Bhaskarapillai, Anupkumar; Velmurugan, Sankaralingam

2017-07-15

Antimony is classified as a pollutant of priority importance by USEPA. We have earlier reported the synthesis of nano-titania impregnated epichlorohydrin crosslinked chitosan (TA-Cts-Epi) beads, in a format suitable for large scale applications with high sorption capacity for antimony. To understand the sorption mechanism, and to fine tune the bead composition, the effect of crosslinking density on the swelling and sorption properties of the beads was investigated in detail. Epichlorohydrin effected significant changes in physical and sorption properties of the beads. The antimony sorption capacity of the TA-Cts-Epi beads prepared by crosslinking 0.3g non-crosslinked titania-chitosan beads (TA-Cts-NCL) with 6.4mmol epichlorohydrin was 493μmol/g, while those crosslinked with 0.64mmol showed a capacity of 133μmol/g. Whereas, TA-Cts-NCL beads showed a capacity of 75μmol/g. The increase in uptake capacity with increase in crosslinking demonstrated the active involvement of the epichlorohydrin moieties in antimony binding leading to enhanced sorption. Apart from altering the stability, swelling behaviour and sorption kinetics of the beads, crosslinking significantly increased the uptake of the anionic species via electrostatic interactions. Epichlorohydrin crosslinked chitosan beads prepared without TiO 2 also showed similar behaviour. The results demonstrated the involvement of chitosan, TiO 2 and epichlorohydrin in sorption. Copyright © 2017 Elsevier B.V. All rights reserved.

Antimony in the Contaminated Site of El Triunfo, Baja California Sur, Mexico

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Marmolejo-Rodríguez A. J.

2013-04-01

Full Text Available Antimony has properties similar to arsenic with some of its compounds toxic to humans. Therefore it is necessary to control the wastes accumulated by anthropogenic activities, such as mining, where it is in tailings to be released to the environment. According to the Environment Protection Agency, the maximum value in sediments is 11.2 mg Sb kg–1 and the Earth’s crust average is 0.2 mg Sb kg–1. In this semiarid area, the drainage basin El Carrizal is impacted with wastes of an abandoned gold mine at the Mining District El Triunfo (MD – ET which have tailings with 17,600 mg kg–1 of antimony. In the main dry river (arroyo, the Sb content is between 0.6 and 122 mg kg–1. This element is transported from the source throughout the fluvial basin to discharge into the Pacific Ocean. In the arroyo mouth we collected one sedimentary core and the sediment from dunes (28.6 – 45.7 and 6.43 – 7.74 mg Sb kg–1. This research concluded the antimony is enriched in this semiarid system, with Normalized Enrichment Factors severely enriched mainly in arroyo sediments close to the MD-ET

Morphology and antimony segregation of spangles on batch hot-dip galvanized coatings

Science.gov (United States)

Peng, Shu; Lu, Jintang; Che, Chunshan; Kong, Gang; Xu, Qiaoyu

2010-06-01

Spangles produced by batch hot-dip galvanizing process have a rougher surface and a greater surface segregation of alloying element compared with those in continuous hot-dip galvanizing line (CGL), owing to the cooling rate of the former is much smaller than that of the later. Therefore, typical spangles on a batch hot-dipped Zn-0.05Al-0.2Sb alloy coating were investigated. The chemical, morphological characterization and identification of the phases on the spangles were examined by scanning electron microscopy (SEM), backscattered electron imaging (BSE), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The results showed that the coating surface usually exhibited three kinds of spangles: shiny, feathery and dull spangle, of which extensively antimony surface segregation was detected. The nature of precipitate on the coating surface was identified as β-Sb 3Zn 4, The precipitated β-Sb 3Zn 4 particles distributed randomly on the shiny spangle surface, both β-Sb 3Zn 4 particles and dentritic segregation of antimony dispersed in the dendritic secondary arm spacings of the feathery spangle and on the whole dull spangle surface. The dentritic segregation of antimony and precipitation of Sb 3Zn 4 compound are discussed by a proposed model.

Selective liquid-liquid extraction of antimony(III from hydrochloric acid media by N-n-octylaniline in xylene

Directory of Open Access Journals (Sweden)

M. A. ANUSE

2004-04-01

Full Text Available N-n-Octylaniline in xylene was used for the extraction separation of antimony(III from hydrochloric acid media. Antimony(III was extracted quantitatively with 10 mL 4 % N-n-octylaniline in xylene. It was stripped from the organic phase with 0.5 M ammonia and estimated photometrically by the iodide method. The effect of metal ion, acid, reagent concentration and various foreign ions was investigated. The method affords binary and ternary separation of antimony(III from tellurium(IV, selenium(IV, lead(II, bismuth(III, tin(IV, germanium(IV, copper(II, gold(III, iron(III and zinc(II. The method is applicable for the analysis of synthetic mixtures, alloys and semiconductor thin films. It is fast, accurate and precise.

Synthesis, characterization and single crystal X-ray analysis of chlorobis(N,N-dimethyldithiocarbamato-S,S′antimony(III

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H.P.S. Chauhan

2015-07-01

Full Text Available The title compound chlorobis(N,N-dimethyldithiocarbamato-S,S′antimony(III has been prepared in distilled acetonitrile and characterized by physicochemical [melting point and molecular weight determination, elemental analysis (C, H, N, S & Sb], spectral [FT–IR, far IR, NMR (1H & 13C] studies. The crystal and molecular structure was further confirmed using single crystal X-ray diffraction analysis which features a five-coordinate geometry for antimony(III within a ClS4 donor set. The distortion in the co-planarity of ClSbS3 evidences the stereochemical influence exerts by the lone pair of electrons on antimony(III. Two centrosymmetrically related molecule held together via C–H···Cl secondary interaction result in molecular aggregation of the compound.

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.

Low concentrations of antimony impair DNA damage signaling and the repair of radiation-induced DSB in HeLa S3 cells.

Science.gov (United States)

Koch, Barbara; Maser, Elena; Hartwig, Andrea

2017-12-01

Antimony is utilized in a large variety of industrial applications, leading to significant environmental and occupational exposure. Mainly based on animal experiments, the IARC and MAK Commission have classified antimony and its inorganic compounds as Group 2B or 2 carcinogens, respectively. However, the underlying mode(s) of action are still largely unknown. In the present study, we investigated the impact of non-cytotoxic up to cytotoxic concentrations of SbCl 3 on DNA DSB repair and cell cycle control in HeLa S3 cells. We induced DSB by γ-irradiation and analyzed inhibitory actions of antimony on potential molecular targets of the DSB repair machinery. Antimony disturbed cell cycle control, affecting phosphorylation of Chk1. Furthermore, the repair of DSB was impaired in the presence of antimony, as monitored by pulsed-field gel electrophoresis and γH2AX foci formation of cells in G1 and G2 phase. Specifically, BRCA1 and RAD51 were identified as molecular targets. Our results point towards an interference with both non-homologous end-joining (NHEJ) and homologous recombination (HR), and inhibitory effects may be explained by interactions with critical cysteine groups; this needs to be further investigated. Altogether, the results provide further evidence for the impairment of DNA repair processes as one underlying mechanism in antimony-induced carcinogenicity.

Comparative study of the influence of antimony oxide additives (III) and nickel hydroxide (II) on electrochemical behavior of cadmium electrodes

Energy Technology Data Exchange (ETDEWEB)

Kadnikova, N.V.; Lvova, L.A.; Ryabskaya, I.A.

1983-01-01

Comparative study of the influence of additives indicated that with partial or complete replacement in the active mass of the cadmium electrode of nickel hydroxide (II) by antimony oxide (III), the electrochemical characteristics do not significantly change. During prolonged storage of charged cadmium electrodes the presence of nickel hydroxide (II) and intermetal compound (IMC) of cadmium with nickel is formed and the specific surface increases. In the case of adding antimony (III) formation of noticeable quantities of IMC of cadmium with antimony is not observed. The specific surface is reduced during storage.

Preconcentration and Determination of Antimony in Drinking Water Bottled by Modified Nano-Alumina

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M Mohammad Zakizade

2016-01-01

Full Text Available Abstract Introduction: Antimony trioxide (Sb2O3 has been utilized as a catalyst in polyethylene terephtalate (PET production, and the studies conducted on the bottled water has demonstrated that antimony can be leached from PET bottles into drinking water. Methods: In this study, a simple method was applied in order to determine the trace amount of antimony in bottled drinking water based on preconcentration /solid phase extraction. The nano alumina modified with Schiff base ligand was used in regard with Sb preconcentration. The experiments were performed in a continuous system and HCI was used as eluent of Sb ion. Several chemical and flow variables were optimized for a quantitative preconcentration and determination of Sb ion. The atomic absorption spectroscopy was used to determine Sb ion concentration. In order to study the keeping conditions on the leaching of Sb ion from PET plastic, drinking water bottles were kept in different conditions(room temperature, sunny light and -18˚C. Results: The calibration graph was linear in the range of 0.5 to 15.0 ppm Sb with detection limit of 0.055 ppm. The flow rate of sample was optimized in range of 1.0-9.0 mLmin-1 and Sb ion can be quantitatively eluted at 90 Vsample: Veluent retio. Conclusion: The study results revealed that the modified nano alumina is an effective sorbent in regard with absorbing Sb ion from water and HCI 1M can be used as an appropriate eluent. Maximum leaching of Sb ion is observed when the bottled drinking water was exposed to the sun light. Keywords: Antimony; Bottled drinking water; Modified alumina; Preconcentration

The Potential for the Treatment of Antimony-Containing Wastewater by Iron-Based Adsorbents

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Ren-Jian Deng

2017-10-01

Full Text Available Antimony (Sb and its compounds are considered as global priority pollutants. Elevated concentrations of antimony in natural and industrial process wastewater are of global concern, particularly given interest in the potential toxicity and harm to the environment from aquatic exposure. Iron-based materials for treatment by adsorption are widely regarded to have potential merit for the removal of trace contaminants from water and especially in the search for efficient and low-cost techniques. In this paper, we review the application of iron-based materials in the sorption treatment of antimony contaminated water. The interaction of Sb is discussed in relation to adsorption performance, influencing factors, mechanism, modelling of adsorption (isotherm, kinetic and thermodynamic models, advantages, drawbacks and the recent achievements in the field. Although iron-based adsorbents show promise, the following three aspects are in need of further study. Firstly, a select number of iron based binary metal oxide adsorbents should be further explored as they show superior performance compared to other systems. Secondly, the possibility of redox reactions and conversion between Sb(III and Sb(V during the adsorption process is unclear and requires further investigation. Thirdly, in order to achieve optimized control of preferential adsorption sites and functional groups, the mechanism of antimony removal has to be qualitatively and quantitatively resolved by combining the advantages of advanced characterization techniques such as Fourier transform infrared spectroscopy(FTIR, X-ray photoelectron spectroscopy (XPS, Atomic force microscope(AFM, X-ray absorption near edge structure(XANES, and other spectroscopic methods. We provide details on the achievements and limitations of each of these stages and point to the need for further research.

Effect of Annealing on the Properties of Antimony Telluride Thin Films and Their Applications in CdTe Solar Cells

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Zhouling Wang

2014-01-01

Full Text Available Antimony telluride alloy thin films were deposited at room temperature by using the vacuum coevaporation method. The films were annealed at different temperatures in N2 ambient, and then the compositional, structural, and electrical properties of antimony telluride thin films were characterized by X-ray fluorescence, X-ray diffraction, differential thermal analysis, and Hall measurements. The results indicate that single phase antimony telluride existed when the annealing temperature was higher than 488 K. All thin films exhibited p-type conductivity with high carrier concentrations. Cell performance was greatly improved when the antimony telluride thin films were used as the back contact layer for CdTe thin film solar cells. The dark current voltage and capacitance voltage measurements were performed to investigate the formation of the back contacts for the cells with or without Sb2Te3 buffer layers. CdTe solar cells with the buffer layers can reduce the series resistance and eliminate the reverse junction between CdTe and metal electrodes.

Dissimilatory antimonate reduction and production of antimony trioxide microcrystals by a novel microorganism.

Science.gov (United States)

Abin, Christopher A; Hollibaugh, James T

2014-01-01

Antimony (Sb) is a metalloid that has been exploited by humans since the beginning of modern civilization. The importance of Sb to such diverse industries as nanotechnology and health is underscored by the fact that it is currently the ninth-most mined metal worldwide. Although its toxicity mirrors that of its Group 15 neighbor arsenic, its environmental chemistry is very different, and, unlike arsenic, relatively little is known about the fate and transport of Sb, especially with regard to biologically mediated redox reactions. To further our understanding of the interactions between microorganisms and Sb, we have isolated a bacterium that is capable of using antimonate [Sb(V)] as a terminal electron acceptor for anaerobic respiration, resulting in the precipitation of antimonite [Sb(III)] as microcrystals of antimony trioxide. The bacterium, designated strain MLFW-2, is a sporulating member of a deeply branching lineage within the order Bacillales (phylum Firmicutes). This report provides the first unequivocal evidence that a bacterium is capable of conserving energy for growth and reproduction from the reduction of antimonate. Moreover, microbiological antimonate reduction may serve as a novel route for the production of antimony trioxide microcrystals of commercial significance to the nanotechnology industry.

A review of slow-release fluoride devices.

Science.gov (United States)

Toumba, K J; Al-Ibrahim, N S; Curzon, M E J

2009-09-01

Fluoride has been used to combat dental caries using a number of different clinical approaches. An exciting relatively new development is fluoride slow-releasing devices that consistently elevate intra-oral fluoride levels of plaque and saliva for prolonged periods of up to two years. The literature on the use of slow-releasing fluoride devices in dentistry were reviewed. A Medline search on key words was carried out. All papers in English were individually reviewed. Slow-releasing fluoride devices have been shown to be effective in elevating salivary fluoride levels in both animals and human studies and to enhance the remineralisation of dental enamel. They have been demonstrated to be safe to use and without the risk of fluoride toxicity. A double blind randomised clinical trial demonstrated 76% fewer new carious surface increment in high caries-risk children after two years. These devices have a number of potential uses in dentistry and in particular have great potential for caries prevention of non-compliant high caries-risk groups.

Effects of fluoridated milk on root dentin remineralization.

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Wolfgang H Arnold

Full Text Available The prevalence of root caries is increasing with greater life expectancy and number of retained teeth. Therefore, new preventive strategies should be developed to reduce the prevalence of root caries. The aim of this study was to investigate the effects of fluoridated milk on the remineralization of root dentin and to compare these effects to those of sodium fluoride (NaF application without milk.Thirty extracted human molars were divided into 6 groups, and the root cementum was removed from each tooth. The dentin surface was demineralized and then incubated with one of the following six solutions: Sodium chloride NaCl, artificial saliva, milk, milk+2.5 ppm fluoride, milk+10 ppm fluoride and artificial saliva+10 ppm fluoride. Serial sections were cut through the lesions and investigated with polarized light microscopy and quantitative morphometry, scanning electron microscopy (SEM and energy-dispersive X-ray spectroscopy (EDS. The data were statistically evaluated using a one-way ANOVA for multiple comparisons.The depth of the lesion decreased with increasing fluoride concentration and was the smallest after incubation with artificial saliva+10 ppm fluoride. SEM analysis revealed a clearly demarcated superficial remineralized zone after incubation with milk+2.5 ppm fluoride, milk+10 ppm fluoride and artificial saliva+10 ppm fluoride. Ca content in this zone increased with increasing fluoride content and was highest after artificial saliva+10 ppm fluoride incubation. In the artificial saliva+10 ppm fluoride group, an additional crystalline layer was present on top of the lesion that contained elevated levels of F and Ca.Incubation of root dentin with fluoridated milk showed a clear effect on root dentin remineralization, and incubation with NaF dissolved in artificial saliva demonstrated a stronger effect.

Fluoride Increase in Saliva and Dental Biofilm due to a Meal Prepared with Fluoridated Water or Salt: A Crossover Clinical Study.

Science.gov (United States)

Lima, Carolina V; Tenuta, Livia M A; Cury, Jaime A

2018-06-07

Knowledge about fluoride delivery to oral fluids from foods cooked with fluoridated water and salt is scarce, and no study has evaluated fluoride concentrations in saliva or biofilm during meal consumption. In this randomized double-blind crossover study, 12 volunteers ingested meals (rice, beans, meat, and legumes) prepared with nonfluoridated water and salt (control group), fluoridated water (0.70 mg F/L; water group), and fluoridated salt (183.7 mg F/kg; salt group). Whole saliva was collected before meal ingestion, during mastication, and up to 2 h after meal ingestion. Dental biofilm was collected before and immediately after meal ingestion. Fluoride concentrations in saliva and dental biofilm were determined by an ion-specific electrode. The mean (±standard deviation; n = 4) fluoride concentrations in meals prepared for the control, water, and salt groups were 0.039 ± 0.01, 0.43 ± 0.04, and 1.71 ± 0.32 μg F/g, respectively. The three groups had significantly different fluoride concentrations in saliva collected during mastication (p water > control). The fluoride concentration in saliva returned to baseline 30 min after meal ingestion in the water group but remained high for up to 2 h in the salt group (p = 0.002). The fluoride concentration in biofilm fluid differed only between the salt and control groups (p = 0.008). The mastication of foods cooked with fluoridated water and salt increases fluoride concentrations in oral fluids and may contribute to the local effect of these community-based fluoride interventions on caries control. © 2018 S. Karger AG, Basel.

Comprehensive thermal and structural characterization of antimony-phosphate glass

Science.gov (United States)

Moustafa, S. Y.; Sahar, M. R.; Ghoshal, S. K.

For the first time, we prepare new ternary glass systems of composition (95-x)Sb2O3-xP2O5-5MgO, where x = 45, 40, 35 mol%; (85-x)Sb2O3-xP2O5-15MgO, where x = 55, 35, 25 mol%; (75-x)Sb2O3-xP2O5-25MgO, where x = 45, 35, 25 mol%; and 60Sb2O3-(40-x)P2O5-xMgO, where x = 10, 20 mol% via melt-quenching method. Synthesized glasses are characterized using XRD, FESEM, EDX, and TG/DTA measurements. The influence of varying modifier concentrations on their thermal properties is evaluated. The XRD patterns confirmed the amorphous nature of samples. SEM images demonstrated interesting phase formation with ribbons-like texture. Five crystalline phases are evidenced in the ternary diagram which are antimony phosphate and antimony orthophosphate as major phases as well as magnesium phosphate, magnesium cyclo-tetraphosphate and cervantite as minor phases. EDX spectra detected the right elemental traces. Detailed thermal analysis of these glasses revealed their high-molecular polymer character for Sb2O3 content greater than 50 mol%. Three different glass transition temperatures are achieved around 276, 380-381 and 422-470 °C depending on the composition. Furthermore, the solidus and liquidus temperature are found to decrease with increasing Sb2O3 and increases for MgO contents till 15 mol% and then decrease, where the lowest recorded solidus temperature is 426 °C. This observation may open up new research avenues for antimony based ternary glasses and an exploitation of the derived results for optoelectronics applications, photonic devices and non-linear optical devices.

Estimation of atmospheric fluoride by limed filter papers

International Nuclear Information System (INIS)

Smith, D.R.

1988-09-01

The limed filter paper method of static sampling of atmospheric fluoride is reviewed in this report. Use of the technique, in conjunction with precise measurement of the absorbed fluoride and calibration with dynamic air sampling techniques, to estimate atmospheric fluoride levels, is considered to give only qualitative data (± 50%). The limed filter paper method is site specific due to variations in meteorological conditions. Its main value is to indicate seasonal and annual trends in fluoride exposure of vegetation. Subject to these considerations, the lower and upper limits of atmospheric fluoride exposure and the applicability to atmospheric fluoride estimation under routine or emergency fluoride release conditions are discussed, with special emphasis on the limiting factors

Vapor pressures of dimethylcadmium, trimethylbismuth, and tris(dimethylamino)antimony

Czech Academy of Sciences Publication Activity Database

Morávek, Pavel; Fulem, Michal; Pangrác, Jiří; Hulicius, Eduard; Růžička, K.

2013-01-01

Roč. 360, Dec (2013), s. 106-110 ISSN 0378-3812 R&D Projects: GA ČR GA13-15286S; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : vapor pressure * dimethylcadmium * trimethylbismuth * tris(dimethylamino)antimony * sublimation and vaporization enthalpy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.241, year: 2013

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.)

Atmospheric fluoride levels in some Ontario peach orchards

Energy Technology Data Exchange (ETDEWEB)

Drowley, W B; Rayner, A C; Jephcott, C M

1963-10-01

As a result of suture injury to peaches, a survey was taken to determine monthly atmospheric fluoride levels in the soft fruit-growing area of the Niagara Peninsula of Ontario. Although the injury was confined to a few orchards, it was found necessary to locate stations for fluoride sampling over a wide area. The limed-paper candle method was used for fluoride collection. Unwashed and washed peach leaves were analyzed for fluoride content. Fluoride was separated from all samples by the Willard-Winter distillation procedure and estimated colorimetrically. It was found that a general background level of atmospheric fluoride existed in the whole surveyed area and that the levels were highest in and near the area of peach injury. The fluoride content of peach leaves was also highest in this area. The coincidence of high fluoride levels and suture injury to peaches suggests that atmospheric fluoride was the causal agent. When lime sprays were applied to peach trees in the damaged area, a reduction in the incidence of suture injury was observed.

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.

Bacterial Communities in the Groundwater of Xikuangshan Antimony Mine, China

Science.gov (United States)

Wu, M.; Wang, H.; Wang, N.; Wang, M.

2017-12-01

Xikuangshan (XKS) is the biggest antimony (Sb) mine around the word, which causes serious environmental contamination due to the mining actives. To fully understand the bacterial compositions in the groundwater around the mining area in XKS and their correlation with environmental factors, groundwater samples were collected and subject to 16S rDNA high throughput sequencing. Results indicated that Proteobacteria (especially Gamma-Proteobacteria) dominated bacterial communities in high-Sb groundwater samples, whereas Bacteroidetes predominated in low-Sb groundwater. Furthermore, antimony concentration was found to be the most significant factor shaping bacterial communities (P=0.002) with an explanation of 9.16% of the variation. Other factors such as pH, contents of Mg, Ca and orthophosphate were also observed to significantly correlate with bacterial communities. This was the first report to show the important impact of Sb concentration on bacterial community structure in the groundwater in the mining area. Our results will enhance the understanding of subsurface biogeochemical processes mediated by microbes.

First-line therapy for human cutaneous leishmaniasis in Peru using the TLR7 agonist imiquimod in combination with pentavalent antimony.

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Cesar Miranda-Verastegui

2009-07-01

Full Text Available Current therapies for cutaneous leishmaniasis are limited by poor efficacy, long-term course of treatment, and the development of resistance. We evaluated if pentavalent antimony (an anti-parasitic drug combined with imiquimod (an immunomodulator was more effective than pentavalent antimony alone in patients who had not previously been treated.A randomized double-blind clinical trial involving 80 cutaneous leishmaniasis patients was conducted in Peru. The study subjects were recruited in Lima and Cusco (20 experimental and 20 control subjects at each site. Experimental arm: Standard dose of pentavalent antimony plus 5% imiquimod cream applied to each lesion three times per week for 20 days. Control arm: Standard dose of pentavalent antimony plus placebo (vehicle cream applied as above. The primary outcome was cure defined as complete re-epithelization with no inflammation assessed during the 12 months post-treatment period.Of the 80 subjects enrolled, 75 completed the study. The overall cure rate at the 12-month follow-up for the intention-to-treat analysis was 75% (30/40 in the experimental arm and 58% (23/40 in the control arm (p = 0.098. Subgroup analyses suggested that combination treatment benefits were most often observed at the Cusco site, where L. braziliensis is the prevalent species. Over the study period, only one adverse event (rash was recorded, in the experimental arm.The combination treatment of imiquimod plus pentavalent antimony performed better than placebo plus pentavalent antimony, but the difference was not statistically significant.Clinical Trials.gov NCT00257530.

Fluoride and Water (For Parents)

Science.gov (United States)

... risk of tooth decay" on the label. The Controversy Over Fluoride Opponents of water fluoridation have questioned ... Us Contact Us Partners Editorial Policy Permissions Guidelines Privacy Policy & Terms of Use Notice of Nondiscrimination Visit ...

Failure of both azithromycin and antimony to treat cutaneous leishmaniasis in Manaus, AM, Brazil Falha da azitromicina e do antimonial no tratamento da leishmaniose cutânea em Manaus, AM, Brasil

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Alan César Teixeira

2008-06-01

Full Text Available A non-randomized controlled clinical trial was carried outin order to evaluate both azithromycin and antimony efficacy in cutaneous leishmaniasis in Manaus, AM, Brazil. Forty nine patients from both genders, aged 14 to 70, with cutaneous ulcers for less than three months and a positive imprint for Leishmania spp. amastigotes were recruited into two groups. Group I (26 patients received a daily-single oral dose of 500 mg of azithromycin for 20 days and Group II (23 patients received a daily-single intramuscular dose of 20 mg/kg of meglumine antimony, also for 20 days. Azithromycin cured three of 24 (12.5% patients on days 60, 90 and 120 respectively whereas therapeutic failure was considered in 21 of 24 (87.5% cases. In group II, antimony cured eight of 19 (42.1% cases as follows: three on day 30, one each on day 60 and day 90, and three on day 120. Therapeutic failure occurred in 11 of 19 (57.9% individuals. The efficacy of antimony for leishmaniasis was better than azithromycin but analysis for the intention-to-treat response rate did not show statistical difference between them. Although azithromycin was better tolerated, it showed a very low efficacy to treat cutaneous leishmaniasis in Manaus.Com o objetivo de avaliar a eficácia da azitromicina no tratamento da leishmaniose cutânea, foi realizado ensaio comparativo, em Manaus. Foram recrutados 49 pacientes de ambos os sexos, com idades entre 14 e 70 anos que apresentassem úlceras cutâneas com menos de três meses de evolução e que tivessem exame direto positivo para amastigotas de leishmânia. Estes pacientes foram alocados em dois grupos assim: Grupo I (26 recebeu uma dose diária de 500 mg de azitromicina pela via oral durante 20 dias e o Grupo II, recebeu uma dose diária de 20 mg/kg de antimoniato de meglumina por via intramuscular, durante 20 dias. Do grupo da azitromicina, três (12,5% de 24 pacientes curaram 60, 90 e 120 dias, respectivamente, enquanto, em 21 (87,5% de 24 houve

Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

OpenAIRE

Richard Sauerheber

2013-01-01

The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity ...

Theoretical and experimental studies for selective removal of antimony from zircaloy using thiourea grafted polystyrene adsorbent. Contributed Paper MS-01

International Nuclear Information System (INIS)

Arora, Jyotsna S.; Gaikar, Vilas G.

2014-01-01

During the dissolution step in nuclear fuel reprocessing, hulls consisting of essentially zircaloy clad are produced as high active solid waste. For recovery and reuse of zircaloy from this solid waste, 58 Co and 125 Sb which are present as the activation products of cobalt and tin in zircaloy tubes need to be separated. The present work involves selective sorption of antimony on thiourea grafted polymeric adsorbent in the presence of cobalt and zirconium. The effect of pH for the optimum uptake of antimony ions was studied. Since the variation in pH influences the antimony species formed in the solution, density functional theoretical (DFT) studies were performed in order to understand the complexation of the metal species with the grafted adsorbent at the molecular level. The highest occupied molecular orbital (HOMO) of the adsorbent which is located on S atom of loaded thiourea interacts with lowest unoccupied molecular orbital (LUMO) of Sb(V). The grafted adsorbent exhibits higher interaction with antimony species as compared to cobalt and zirconium. The metal-S bond distances are in good agreement with the XRD values for similar systems. Including the effect of solvation model helps in validation of simulation results with experimental adsorption data suggesting the application of thiourea grafted adsorbent for antimony separation. (author)

Diffuse x-ray scattering and transmission electron microscopy study of defects in antimony-implanted silicon

Science.gov (United States)

Takamura, Y.; Marshall, A. F.; Mehta, A.; Arthur, J.; Griffin, P. B.; Plummer, J. D.; Patel, J. R.

2004-04-01

Ion implantation followed by laser annealing has been used to create supersaturated and electrically active concentrations of antimony in silicon. Upon subsequent thermal annealing, however, these metastable dopants deactivate towards the equilibrium solubility limit. In this work, the formation of inactive antimony structures has been studied with grazing incidence diffuse x-ray scattering, and transmission electron microscopy, and the results are correlated to previous high-resolution x-ray diffraction data. We find that at a concentration of 6.0×1020 cm-3, small, incoherent clusters of radius 3-4 Å form during annealing at 900 °C. At a higher concentration of 2.2×1021 cm-3, deactivation at 600 °C occurs through the formation of small, antimony aggregates and antimony precipitates. The size of these precipitates from diffuse x-ray scattering is roughly 15 Å in radius for anneal times from 15 to 180 seconds. This value is consistent with the features observed in high-resolution and mass contrast transmission electron microscopy images. The coherent nature of the aggregates and precipitates causes the expansion of the surrounding silicon matrix as the deactivation progresses. In addition, the sensitivity of the diffuse x-ray scattering technique has allowed us to detect the presence of small clusters of radius ˜2 Å in unprocessed Czochralski silicon wafers. These defects are not observed in floating zone silicon wafers, and are tentatively attributed to thermal donors.

Fluoride Removal from Water by Reverse Osmosis Membrane

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Sara Namavar

2013-09-01

Full Text Available As fluoride concentration in drinking water is one of the effective parameters in human health, finding the way to remove excess amount of fluoride from drinking water is very important in water supply projects. Today, with developing in technology and finding new methods, the use of membrane technology for producing fresh water get improved. In this study the efficiency of reverse osmosis method to remove fluoride from water was investigated. Initial concentration of fluoride, sulfate and electrical conductivity in feed water and the effect of associated cation with fluoride ion were studied. All tests adapted from “Standard Methods for Examination of Water and Wastewater”. Determination of fluoride concentration was done according the standard SPANDS method by using a spectrophotometer DR/5000. Obtain results show that with increasing in concentration of fluoride and sulfate and electrical conductivity in feed water the efficiency of RO membrane to remove fluoride reduced. In addition, this efficiency for CaF2 was higher than NaF.

Liquid-liquid extraction of arsenic, antimony, selenium and tellurium by zinc diethyldithiocarbamate

International Nuclear Information System (INIS)

Bajo, S.; Wyttenbach, A.

1978-03-01

The authors report the solvent extraction, oxidation, reduction, extraction in the presence of iron, and reextraction of arsenic, antimony, selenium and tellurium. These processes were studied using radioactive tracers. (G.T.H.)

FLUORIDE: A REVIEW OF USE AND EFFECTS ON HEALTH.

Science.gov (United States)

Kanduti, Domen; Sterbenk, Petra; Artnik, Barbara

2016-04-01

Appropriate oral health care is fundamental for any individual's health. Dental caries is still one of the major public health problems. The most effective way of caries prevention is the use of fluoride. The aim of our research was to review the literature about fluoride toxicity and to inform physicians, dentists and public health specialists whether fluoride use is expedient and safe. Data we used in our review were systematically searched and collected from web pages and documents published from different international institutions. Fluoride occurs naturally in our environment but we consume it in small amounts. Exposure can occur through dietary intake, respiration and fluoride supplements. The most important factor for fluoride presence in alimentation is fluoridated water. Methods, which led to greater fluoride exposure and lowered caries prevalence, are considered to be one of the greatest accomplishments in the 20th century`s public dental health. During pregnancy, the placenta acts as a barrier. The fluoride, therefore, crosses the placenta in low concentrations. Fluoride can be transmitted through the plasma into the mother's milk; however, the concentration is low. The most important action of fluoride is topical, when it is present in the saliva in the appropriate concentration. The most important effect of fluoride on caries incidence is through its role in the process of remineralization and demineralization of tooth enamel. Acute toxicity can occur after ingesting one or more doses of fluoride over a short time period which then leads to poisoning. Today, poisoning is mainly due to unsupervised ingestion of products for dental and oral hygiene and over-fluoridated water. Even though fluoride can be toxic in extremely high concentrations, it`s topical use is safe. The European Academy of Paediatric Dentistry (EAPD) recommends a preventive topical use of fluoride supplements because of their cariostatic effect.

Strontium-90 fluoride data sheet

Energy Technology Data Exchange (ETDEWEB)

Fullam, H.T.

1981-06-01

This report is a compilation of available data and appropriate literature references on the properties of strontium-90 fluoride and nonradioactive strontium fluoride. The objective of the document is to compile in a single source pertinent data to assist potential users in the development, licensing, and use of /sup 90/SrF/sub 2/-fueled radioisotope heat sources for terrestrial power conversion and thermal applications. The report is an update of the Strontium-90 Fluoride Data Sheet (BNWL-2284) originally issued in April 1977.

Decreased antimony uptake and overexpression of genes of thiol metabolism are associated with drug resistance in a canine isolate of Leishmania infantum

Directory of Open Access Journals (Sweden)

Verónica Gómez Pérez

2016-08-01

Full Text Available Visceral leishmaniasis (VL caused by the protozoan parasite Leishmania infantum, is one of the most important zoonotic diseases affecting dogs and humans in the Mediterranean area. The presence of infected dogs as the main reservoir host of L. infantum is regarded as the most significant risk for potential human infection. We have studied the susceptibility profile to antimony and other anti-leishmania drugs (amphotericin B, miltefosine, paromomycin in Leishmania infantum isolates extracted from a dog before and after two therapeutic interventions with meglumine antimoniate (subcutaneous Glucantime®, 100 mg/kg/day for 28 days. After the therapeutic intervention, these parasites were significantly less susceptible to antimony than pretreatment isolate, presenting a resistance index of 6-fold to SbIII for promastigotes and >3-fold to SbIII and 3-fold to SbV for intracellular amastigotes. The susceptibility profile of this resistant L. infantum line is related to a decreased antimony uptake due to lower aquaglyceroporin-1 expression levels. Additionally, other mechanisms including an increase in thiols and overexpression of enzymes involved in thiol metabolism, such as ornithine decarboxylase, trypanothione reductase, mitochondrial tryparedoxin and mitochondrial tryparedoxin peroxidase, could contribute to the resistance as antimony detoxification mechanisms. A major contribution of this study in a canine L. infantum isolate is to find an antimony-resistant mechanism similar to that previously described in other human clinical isolates.

Morphology and antimony segregation of spangles on batch hot-dip galvanized coatings

Energy Technology Data Exchange (ETDEWEB)

Peng Shu, E-mail: shu.peng@mail.scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, No. 371 Wushan Road, Tianhe District, Guangzhou 510640 (China); Lu Jintang; Che Chunshan; Kong Gang; Xu Qiaoyu [School of Materials Science and Engineering, South China University of Technology, No. 371 Wushan Road, Tianhe District, Guangzhou 510640 (China)

2010-06-01

Spangles produced by batch hot-dip galvanizing process have a rougher surface and a greater surface segregation of alloying element compared with those in continuous hot-dip galvanizing line (CGL), owing to the cooling rate of the former is much smaller than that of the later. Therefore, typical spangles on a batch hot-dipped Zn-0.05Al-0.2Sb alloy coating were investigated. The chemical, morphological characterization and identification of the phases on the spangles were examined by scanning electron microscopy (SEM), backscattered electron imaging (BSE), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The results showed that the coating surface usually exhibited three kinds of spangles: shiny, feathery and dull spangle, of which extensively antimony surface segregation was detected. The nature of precipitate on the coating surface was identified as {beta}-Sb{sub 3}Zn{sub 4}, The precipitated {beta}-Sb{sub 3}Zn{sub 4} particles distributed randomly on the shiny spangle surface, both {beta}-Sb{sub 3}Zn{sub 4} particles and dentritic segregation of antimony dispersed in the dendritic secondary arm spacings of the feathery spangle and on the whole dull spangle surface. The dentritic segregation of antimony and precipitation of Sb{sub 3}Zn{sub 4} compound are discussed by a proposed model.

Potential fluoride toxicity from oral medicaments: A review

OpenAIRE

Rizwan Ullah; Muhammad Sohail Zafar; Nazish Shahani

2017-01-01

The beneficial effects of fluoride on human oral health are well studied. There are numerous studies demonstrating that a small amount of fluoride delivered to the oral cavity decreases the prevalence of dental decay and results in stronger teeth and bones. However, ingestion of fluoride more than the recommended limit leads to toxicity and adverse effects. In order to update our understanding of fluoride and its potential toxicity, we have described the mechanisms of fluoride metabolism, tox...

Low-levels of fluoride in plaque and saliva and their effects on the demineralisation and remineralisation of enamel; role of fluoride toothpastes.

Science.gov (United States)

Lynch, R J M; Navada, R; Walia, R

2004-01-01

To summarise support for current consensus on the likely means by which fluoride toothpastes reduce caries and review some relevant studies of the effect of low levels of fluoride on the demineralisation and remineralisation of enamel. The major anti-caries effect of fluoride toothpastes is thought to result from small but protracted elevations in levels of fluoride in plaque and saliva. Fluoride incorporated into enamel systemically does not reduce enamel solubility sufficiently to exert an anti-caries effect. Fluoride has the potential to exert an anti-caries benefit largely through three mechanisms; inhibition of demineralisation, promotion of remineralisation and interference with bacterial growth and metabolism. However, the low levels of fluoride thought to influence caries are insufficient to have a significant effect via the latter mechanism. Thus reductions in caries resulting from the use of fluoride toothpastes can be linked to modification of the demineralisation/remineralisation balance by direct effects on dental mineral exerted topically by low levels of fluoride. Numerous in vitro studies have shown that low levels of fluoride, typical of those found after many hours in resting plaque and saliva, and resulting from the regular use of fluoride toothpastes, can have a profound effect on enamel demineralisation and remineralisation.

Behavior of ruthenium, cesium and antimony during simulated HLLW vitrification

International Nuclear Information System (INIS)

Klein, M.; Weyers, C.; Goossens, W.R.A.

1985-01-01

The behavior of ruthenium, cesium, and antimony during the vitrification of simulated high-level radioactive liquid wastes (HLLW) in a liquid fed melter was studied on a laboratory scale and on a semi-pilot scale. In the laboratory melter of a 2.5 kg capacity, a series of tests with the simulate traced with 103 Ru, 134 Cs and 124 Sb, has shown that the Ru and Cs losses to the melter effluent are generally higher than 10% whereas the antimony losses remain lower than 0.4%. A wet purification system comprising in series, a dust scrubber, a condenser, an ejector venturi and an NOx washing column retains most of the activity present in the off-gas so that the release fractions for Ru at the absolute filter inlet ranges between 5.10 -3 to 5.10 -5 % of the Ru fed, for Cs the corresponding release fraction ranges between 3.10 -3 to 10 -4 % and for Sb the release fraction ranges between 1.7 10 -4 to 1.7 10 -5 %. The same experiments were performed at a throughput of 1 to 2 1 h -1 of simulated solution in the semi-pilot scale unit RUFUS. The RUFUS unit comprises a glass melter with a 50 kg molten glass capacity and the wet purification train comprises in series a dust scrubber, a condenser, an ejector venturi and an NOx washing column. The tracer tests were restricted to 103 Ru and 134 Cs since the laboratory tests had shown that the antimony losses were very low. The results of the tests are presented

Study of the behaviour of some heavy elements in solvents containing hydrogen fluoride; Etude du comportement de quelques elements lourds dans des solvants a base d'acide fluorhydrique

Energy Technology Data Exchange (ETDEWEB)

Tarnero, M [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1967-01-01

The anhydrous liquid mixtures: dinitrogen tetroxide-hydrogen fluoride and antimony pentafluoride-hydrogen fluoride were studied as solvents for heavy elements interesting nuclear energy: uranium, thorium, zirconium and for some of their compounds. For N{sub 2}O{sub 4}-HF mixtures, electric conductivity measurements and liquid phase infrared spectra were also obtained. Uranium and zirconium tetrafluoride are much more soluble in N{sub 2}O{sub 4}-HF mixtures than in pure hydrogen fluoride. Uranium dissolved in these mixtures is pentavalent. In SbF{sub 5}-HF mixtures, uranium dissolves with hydrogen evolution and becomes trivalent. The solid compound resulting from the dissolution is a fluoro-antimonate: U(SbF{sub 6}){sub 3}. (author) [French] On a etudie les melanges liquides anhydres: peroxyde d'azote-acide fluorhydrique et pentafluorure d'antimoine-acide fluorhydrique comme solvants d'elements lourds interessant l'energie nucleaire: uranium, thorium, zirconium et de quelques uns de leurs composes. Pour les melanges N{sub 2}O{sub 4}-HF on a egalement effectue des mesures de conductivite electrique, ainsi que des spectres d'absorption infrarouge en phase liquide. Le tetrafluorure d'uranium et le tetrafluorure de zirconium sont beaucoup plus solubles dans les melanges N{sub 2}O{sub 4}-HF que dans l'acide fluorhydrique. L'uranium dissous dans ces melanges est a l'etat pentavalent. Dans les melanges SbF{sub 5}-HF l'uranium se dissout avec degagement d'hydrogene et passe a l'etat trivalent. Le compose solide resultant de la dissolution est un fluoantimoniate: U(SbF{sub 6}){sub 3}. (auteur)

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;

Direct separation of arsenic and antimony oxides by high-temperature filtration with porous FeAl intermetallic.

Science.gov (United States)

Zhang, Huibin; Liu, Xinli; Jiang, Yao; Gao, Lin; Yu, Linping; Lin, Nan; He, Yuehui; Liu, C T

2017-09-15

A temperature-controlled selective filtration technology for synchronous removal of arsenic and recovery of antimony from the fume produced from reduction smelting process of lead anode slimes was proposed. The chromium (Cr) alloyed FeAl intermetallic with an asymmetric pore structure was developed as the high-temperature filter material after evaluating its corrosive resistance, structural stability and mechanical properties. The results showed that porous FeAl alloyed with 20wt.% Cr had a long term stability in a high-temperature sulfide-bearing environment. The separation of arsenic and antimony trioxides was realized principally based on their disparate saturated vapor pressures at specific temperature ranges and the asymmetric membrane of FeAl filter elements with a mean pore size of 1.8μm. Pilot-scale filtration tests showed that the direct separation of arsenic and antimony can be achieved by a one-step or two-step filtration process. A higher removal percentage of arsenic can reach 92.24% at the expense of 6∼7% loss of antimony in the two-step filtration process at 500∼550°C and 300∼400°C. The FeAl filters had still good permeable and mechanical properties with 1041h of uninterrupted service, which indicates the feasibility of this high-temperature filtration technology. Copyright © 2017. Published by Elsevier B.V.

Acute toxicity of ingested fluoride.

Science.gov (United States)

Whitford, Gary Milton

2011-01-01

This chapter discusses the characteristics and treatment of acute fluoride toxicity as well as the most common sources of overexposure, the doses that cause acute toxicity, and factors that can influence the clinical outcome. Cases of serious systemic toxicity and fatalities due to acute exposures are now rare, but overexposures causing toxic signs and symptoms are not. The clinical course of systemic toxicity from ingested fluoride begins with gastric signs and symptoms, and can develop with alarming rapidity. Treatment involves minimizing absorption by administering a solution containing calcium, monitoring and managing plasma calcium and potassium concentrations, acid-base status, and supporting vital functions. Approximately 30,000 calls to US poison control centers concerning acute exposures in children are made each year, most of which involve temporary gastrointestinal effects, but others require medical treatment. The most common sources of acute overexposures today are dental products - particularly dentifrices because of their relatively high fluoride concentrations, pleasant flavors, and their presence in non-secure locations in most homes. For example, ingestion of only 1.8 ounces of a standard fluoridated dentifrice (900-1,100 mg/kg) by a 10-kg child delivers enough fluoride to reach the 'probably toxic dose' (5 mg/kg body weight). Factors that may influence the clinical course of an overexposure include the chemical compound (e.g. NaF, MFP, etc.), the age and acid-base status of the individual, and the elapsed time between exposure and the initiation of treatment. While fluoride has well-established beneficial dental effects and cases of serious toxicity are now rare, the potential for toxicity requires that fluoride-containing materials be handled and stored with the respect they deserve. Copyright © 2011 S. Karger AG, Basel.

Inhibition of cellular oxidation by fluoride

Energy Technology Data Exchange (ETDEWEB)

Borei, H

1945-01-01

An attempt has been made to investigate the inhibition by fluoride of the oxidative processes which occur in the cell by way of the cytochrome oxidase-cytochrome system. Some chemical and physical properties of the fluoride ion are discussed, together with certain quantitative methods for the determination of fluoride. An exhaustive review of the literature concerning the effect of fluoride on enzymic processes has been compiled. The experiments have shown that the point of the attack by fluoride is to be found among the cytochromes. The inhibitory mechanism appears to be such that the haemoprotein is prevented from taking part in the preceding and succeeding links in the reaction chain. The blocking action leaves the prosthetic group of the haemoprotein completely unchanged. The experimental results indicate the formation of a fluorophosphoprotein complex, analogous to that found in the case of enolase. Magnesium may possibly play a part in this process.

Acute toxicity of uranium hexafluoride, uranyl fluoride and hydrogen fluoride

International Nuclear Information System (INIS)

Just, R.A.

1988-01-01

Uranium hexafluoride (UF 6 ) released into the atmosphere will react rapidly with moisture in the air to form the hydrolysis products uranyl fluoride (UO 2 F 2 ) and hydrogen fluoride (HF). Uranium compounds such as UF 6 and UO 2 F 2 exhibit both chemical toxicity and radiological effects, while HF exhibits only chemical toxicity. This paper describes the development of a methodology for assessing the human health consequences of a known acute exposure to a mixture of UF 6 , UO 2 F 2 , and HF. 4 refs., 2 figs., 5 tabs

Evaluation of toxic action of fluorides on agricultural plants

Directory of Open Access Journals (Sweden)

V. N. Grishko

2007-03-01

Full Text Available The toxicity of potassium fluoride, sodium fluoride and ammonium fluoride for pea, maize, oat and onion was studied. It was found that the level of the toxic influence had grown with increase of fluoride concentration in the media of growth (from 5 to 100 mg of F–/l. By increase of the toxic influence the agricultural crops are disposed in the following row: oat < onion < maize < pea. Ammonium fluoride demonstrates lesser toxicity, than potassium and sodium fluorides. Under low concentrations of fluoride compounds (5 and 10 mg of F–/l stimulation of roots growth is noted only for the oat.

Determination of Fluoride in Different Toothpaste Formulations

International Nuclear Information System (INIS)

Kamau, N.G.; Njoroge, M.; Njau, M.

1998-01-01

Fluoride ion selective electrode was used to determine fluoride ion concentrations in seven brands of toothpaste. These were the only available formulations found in Kenya. The brands were classified into three groups-fluoridated, non fluoridated or not indicated. However, there was no independent indication of their quantitative composition. The analysed brands had fluoride content between 0.0033% and 0.096%. These values compared favourably with those obtained elsewhere. The calculated lowest limit of detection (LLD) was 0.01 ppmF- . The mean calibration curve gave a slope of of -50.0mV. which was not significantly different from the theoretical value of 5.88mV at 23 degrees celsius at 95% confidence level

Anhydrous hydrogen fluoride electrolyte battery. [Patent application

Science.gov (United States)

Not Available

1972-06-26

It is an object of the invention to provide a primary cell or battery using ammonium fluoride--anhydrous hydrogen fluoride electrolyte having improved current and power production capabilities at low temperatures. It is operable at temperatures substantially above the boiling point of hydrogen fluoride. (GRA)

Fluoride ions vs removal technologies: A study

Directory of Open Access Journals (Sweden)

Jagvir Singh

2016-11-01

Full Text Available Literature reported that drinking water is a precious and scarce resource and it has to be protected and kept free from any kind of contamination. Further, it has to be used carefully without wasting. Literature also reported that fluoride bearing rocks are abundant in India, as a result, fluoride leaches out and contaminates the adjacent water and soil resources. A high concentration of fluoride ions in ground water increases up to more than 30 mg/L. This high concentration of fluoride ions causes many harmful and dangerous effects on our datum. Fluoride ions in larger quantities i.e. 20–80 mg/day taken over a period of 10–20 years result in crippling and skeletal fluorosis, severely damaging the bone. In the present scenario, there is a continuously increasing worldwide concern for the development of fluoride treatment technologies. Possibilities of reducing the high fluorine content in groundwater are by defluorination process/dilution with the surface water which is a very simple technique but the addition of Ca2+ ions to a solution in contact with fluorite when experimented in distilled water caused an appreciable decrease in fluoride concentration. In this review article, we emphasized the relationship between high concentrations of fluoride ions and their compounds and their health impact.

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

Preparation and properties of organo(acetylacetonato)antimony(V) compounds

NARCIS (Netherlands)

Meinema, H.A.; Noltes, J.G.

Organo(acetylacetonato)antimony(V) compounds of the types R2SbCl2Acac, R4SbAcac, PhSbCl3Acac and Cl4SbAcac have been synthesized. The compounds are monomeric in solution. IR and PMR data of these compounds, which contain a chelated Acac ligand have been discussed. Ph2SbCl2Acac shows abnormal

Structural study of chlorine tri-fluoride and bromine penta-fluoride in liquid and solid phase

International Nuclear Information System (INIS)

Rousson, R.

1973-01-01

This research thesis reports the structural study of chlorine tri-fluoride and bromine penta-fluoride between 20 C and about -265 C. After some generalities on these compounds and a presentation of the experimental technique, the author reports and discusses results obtained with these both compounds: Raman spectrum for the liquid and for the solid phase, infrared spectrum for the solid phase, calorimetric measurements. In the case of chlorine tri-fluoride, the author studies the evolution of the liquid spectrum with temperature, shows the existence of an intermediate solid phase, and compares results obtained by Raman spectroscopy and nuclear magnetic resonance. He also applies to bromine penta-fluoride an analysis of normal coordinates of a XF 5 molecule: relationship between force constants and vibration frequencies, application of Wilson method, resolution of the molecular equation, determination of normal vibration modes [fr

Current status of fluoride volatility method development

Energy Technology Data Exchange (ETDEWEB)

Uhlir, J.; Marecek, M.; Skarohlid, J. [UJV - Nuclear Research Institute, Research Centre Rez, CZ-250 68 Husinec - Rez 130 (Czech Republic)

2013-07-01

The Fluoride Volatility Method is based on a separation process, which comes out from the specific property of uranium, neptunium and plutonium to form volatile hexafluorides whereas most of fission products (mainly lanthanides) and higher transplutonium elements (americium, curium) present in irradiated fuel form nonvolatile tri-fluorides. Fluoride Volatility Method itself is based on direct fluorination of the spent fuel, but before the fluorination step, the removal of cladding material and subsequent transformation of the fuel into a powdered form with a suitable grain size have to be done. The fluorination is made with fluorine gas in a flame fluorination reactor, where the volatile fluorides (mostly UF{sub 6}) are separated from the non-volatile ones (trivalent minor actinides and majority of fission products). The subsequent operations necessary for partitioning of volatile fluorides are the condensation and evaporation of volatile fluorides, the thermal decomposition of PuF{sub 6} and the finally distillation and sorption used for the purification of uranium product. The Fluoride Volatility Method is considered to be a promising advanced pyrochemical reprocessing technology, which can mainly be used for the reprocessing of oxide spent fuels coming from future GEN IV fast reactors.

Fluoride ions vs removal technologies: A study

OpenAIRE

Singh, Jagvir; Singh, Prashant; Singh, Anuradha

2016-01-01

Literature reported that drinking water is a precious and scarce resource and it has to be protected and kept free from any kind of contamination. Further, it has to be used carefully without wasting. Literature also reported that fluoride bearing rocks are abundant in India, as a result, fluoride leaches out and contaminates the adjacent water and soil resources. A high concentration of fluoride ions in ground water increases up to more than 30 mg/L. This high concentration of fluoride ions ...

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.

Polycrystalline thin films of antimony selenide via chemical bath deposition and post deposition treatments

International Nuclear Information System (INIS)

Rodriguez-Lazcano, Y.; Pena, Yolanda; Nair, M.T.S.; Nair, P.K.

2005-01-01

We report a method for obtaining thin films of polycrystalline antimony selenide via chemical bath deposition followed by heating the thin films at 573 K in selenium vapor. The thin films deposited from chemical baths containing one or more soluble complexes of antimony, and selenosulfate initially did not show X-ray diffraction (XRD) patterns corresponding to crystalline antimony selenide. Composition of the films, studied by energy dispersive X-ray analyses indicated selenium deficiency. Heating these films in presence of selenium vapor at 573 K under nitrogen (2000 mTorr) resulted in an enrichment of Se in the films. XRD peaks of such films matched Sb 2 Se 3 . Evaluation of band gap from optical spectra of such films shows absorption due to indirect transition occurring in the range of 1-1.2 eV. The films are photosensitive, with dark conductivity of about 2 x 10 -8 (Ω cm) -1 and photoconductivity, about 10 -6 (Ω cm) -1 under tungsten halogen lamp illumination with intensity of 700 W m -2 . An estimate for the mobility life time product for the film is 4 x 10 -9 cm 2 V -1

Experimental determination of the energy levels of the antimony atom (Sb II), ions of the antimony (Sb II, Sb III), mercury (Hg IV) and cesium (Cs X)

International Nuclear Information System (INIS)

Arcimowicz, B.

1993-01-01

The thesis concerns establishing the energy scheme of the electronic levels, obtained from the analysis of the investigated spectra of antimony atom and ions (Sb I, Sb II, Sb III) and higher ionized mercury (Hg IV) and cesium (Cs X) atoms. The experimental studies were performed with optical spectroscopy methods. The spectra of the elements under study obtained in the spectral range from visible (680 nm) to vacuum UV (40 nm) were analysed. The classification and spectroscopic designation of the experimentally established 169 energy levels were obtained on the basis of the performed calculations and the fine structure analysis. The following configurations were considered: 5s 2 5p 2 ns, 5s 2 5p 2 n'd, 5s5p 4 of the antimony atom, 5s 2 5pns, 5s 2 5pn'd, 5s5p 3 of the ion Sb II, 5s 2 ns, 5s 2 n'd, 5s5p 2 of the on Sb III, 5d 8 6p of the ion Hg IV 4d 9 5s and 4d 9 5p Cs X. A reclassification was performed and some changes were introduced to the existing energy level scheme of the antimony atom, with the use of the information obtained from the absorption spectrum taken in the VUV region by the ''flash pyrolysis'' technique. The measurements of the hyperfine splittings in 19 spectral lines belonging to the antimony atom and ions additionally confirmed the assumed classification of the levels involved in these lines. The energy level scheme, obtained for Sb III, was compared to the other ones in the isoelectronic sequence starting with In I. On the basis of the analysis of the Hg IV spectrum it was proved that ground configuration of the three times ionized mercury atom is 5d 9 not 5d 8 6s as assumed until now. The fine structure, established from the analysis of the spectra of the elements under study was examined in multiconfiguration approximation. As a result of the performed calculations the fine structure parameters and wavefunctions were determined for the levels whose energy values were experimentally established in the thesis. (author). 140 refs, 22 figs, 17

THE USE OF FLUORIDE AND ITS EFFECT ON HEALTH

Directory of Open Access Journals (Sweden)

Domen Kanduti

2016-07-01

Full Text Available Appropriate oral health care is fundamental for any individual’s health. Dental caries is still one of the major public health problems. The most effective way of caries prevention is the use of fluoride. Fluoride occurs naturally in our environment and is always present in our lives. However, the concentration differs from area to area. Exposure can occur through diet, respiration and fluoride supplements. During pregnancy, the placenta acts as a barrier. The fluoride, therefore, crosses the placenta in low concentrations. Drinking water in Slovenia is not fluoridated; the amount of naturally present fluoride is very low. Fluoride can be toxic in extremely high concentrations. The most important effect of fluoride on caries incidence is through its role in the process of remineralisation and demineralisation of tooth enamel. The European Academy of Paediatric Dentistry (EAPD recommends a preventive topical use of fluoride supplements because of their cariostatic effect. 

Reaction of Antimony-Uranium Composite Oxide in the Chlorination Treatment of Waste Catalyst - 13521

Energy Technology Data Exchange (ETDEWEB)

Sawada, Kayo [EcoTopia Science Institute (Japan); Hirabayashi, Daisuke; Enokida, Youichi [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan)

2013-07-01

The effect of oxygen gas concentration on the chlorination treatment of antimony-uranium composite oxide catalyst waste was investigated by adding different concentrations of oxygen at 0-6 vol% to its chlorination agent of 0.6 or 6 vol% hydrogen chloride gas at 1173 K. The addition of oxygen tended to prevent the chlorination of antimony in the oxide. When 6 vol% hydrogen chloride gas was used, the addition of oxygen up to 0.1 vol% could convert the uranium contained in the catalyst to U{sub 3}O{sub 8} without any significant decrease in the reaction rate compared to that of the treatment without oxygen. (authors)

Reaction of Antimony-Uranium Composite Oxide in the Chlorination Treatment of Waste Catalyst - 13521

International Nuclear Information System (INIS)

Sawada, Kayo; Hirabayashi, Daisuke; Enokida, Youichi

2013-01-01

The effect of oxygen gas concentration on the chlorination treatment of antimony-uranium composite oxide catalyst waste was investigated by adding different concentrations of oxygen at 0-6 vol% to its chlorination agent of 0.6 or 6 vol% hydrogen chloride gas at 1173 K. The addition of oxygen tended to prevent the chlorination of antimony in the oxide. When 6 vol% hydrogen chloride gas was used, the addition of oxygen up to 0.1 vol% could convert the uranium contained in the catalyst to U 3 O 8 without any significant decrease in the reaction rate compared to that of the treatment without oxygen. (authors)

Histopathological changes of renal tissue following sodium fluoride administration in two consecutive generations of mice. Correlation with the urinary elimination of fluoride.

Science.gov (United States)

Dimcevici Poesina, Nicoleta; Bălălău, Cristian; Nimigean, Vanda Roxana; Nimigean, Victor; Ion, Ion; Baconi, Daniela; Bârcă, Maria; Băran Poesina, Violeta

2014-01-01

The present study was designed to investigate the toxic effects (evaluated as histopathological changes) of sodium fluoride on the kidney in two consecutive generations of NMRI mice. An attempt to correlate the toxicity with the urinary elimination of fluoride has been made, as urinary fluoride excretion has been widely used as an indicator of fluoride intake and exposure. Six mixed (males and females) animal groups have been constituted by dividing the populations of mice derived from pregnant females (named "mothers" 0.5 mg sodium fluoride) treated with 0.5 mg sodium fluoride by daily gavage and pregnant females (named "mothers" 0.25 mg sodium fluoride) treated with 0.25 mg sodium fluoride by daily gavage; three types of sodium fluoride treatments were administrated: homeopathic, allopathic-homeopathic and allopathic. When the animals reached the adulthood, by randomization, they were selected in pairs for giving birth to the second generation of mice. No treatments were administrated to the second generation of mice; thus, the urinary elimination of fluoride in the second generation is attributed to exposure at sodium fluoride before birth. The administration of sodium fluoride to the first generation (F1) is realized until the mice reached the adulthood. For the first generation, the urine was collected at three times, every three weeks: at the age of four weeks, seven weeks and 11 weeks; single sampling urine, at the age of four weeks, has been conducted for the second generation. The urine samples have been analyzed using the ion selective electrode method for fluoride. For the histopathological examination, the animals were killed by cervical dislocation; the kidneys were collected in a 10% formalin solution. The preparation of samples for optical microscopy was realized with Hematoxylin-Eosin staining. The results indicate that the elimination of fluoride was similar (at the second evaluation, at 7-week-old of the first generation) for the both generations

Method for identifying particulate fluoride compounds

Energy Technology Data Exchange (ETDEWEB)

Tufts, B J

1960-01-01

A method is described for identifying particulates containing fluorides and other complex fluorine compounds such as fluorosilicate in samples collected on membrane filters. The filter is treated with lead chloride to precipitate lead chlorofluoride at each fluoride-containing spot. This microspot is identified by examination in a light microscope. Sulfate and phosphate, which also precipitate if present, can be distinguished and do not interfere. Calibrations are given for the fluorides and the more insoluble salts, relating the original particle size to the reaction site size. Thus, the mass of the particles can be calculated. Results of some field tests in an area of fluoride pollution are given, and compared with standard testing procedures.

Community water fluoridation on the Internet and social media.

Science.gov (United States)

Mertz, Aaron; Allukian, Myron

2014-01-01

In the United States, 95 percent of teens and 85 percent of adults use the Internet. Two social media outlets, Facebook and Twitter, reach more than 150 billion users. This study describes anti-fluoridation activity and dominance on the Internet and social media, both of which are community water fluoridation (CWF) information sources. Monthly website traffic to major fluoridation websites was determined from June 2011 to May 2012. Facebook, Twitter, and YouTube fluoridation activity was categorized as "proCWF" or "anti-CWF." Twitter's anti-CWF tweets were further subcategorized by the argument used against CWF. Anti-CWF website traffic was found to exceed proCWF activity five- to sixty-fold. Searching "fluoride" and "fluoridation" on Facebook resulted in 88 to 100 percent anti-CWF groups and pages; "fluoridation" on Twitter and YouTube resulted in 64 percent anti-CWF tweets and 99 percent anti-CWF videos, respectively. "Cancer, " "useless, " and "poisonous" were the three major arguments used against fluoridation. Anti-fluoridation information significantly dominates the Internet and social media. Thousands of people are being misinformed daily about the safety, health, and economic benefits of fluoridation.

Biomonitoring Equivalents for interpretation of urinary fluoride.

Science.gov (United States)

Aylward, L L; Hays, S M; Vezina, A; Deveau, M; St-Amand, A; Nong, A

2015-06-01

Exposure to fluoride is widespread due to its natural occurrence in the environment and addition to drinking water and dental products for the prevention of dental caries. The potential health risks of excess fluoride exposure include aesthetically unacceptable dental fluorosis (tooth mottling) and increased skeletal fragility. Numerous organizations have conducted risk assessments and set guidance values to represent maximum recommended exposure levels as well as recommended adequate intake levels based on potential public health benefits of fluoride exposure. Biomonitoring Equivalents (BEs) are estimates of the average biomarker concentrations corresponding to such exposure guidance values. The literature on daily urinary fluoride excretion rates as a function of daily fluoride exposure was reviewed and BE values corresponding to the available US and Canadian exposure guidance values were derived for fluoride in urine. The derived BE values range from 1.1 to 2.1mg/L (1.2-2.5μg/g creatinine). Concentrations of fluoride in single urinary spot samples from individuals, even under exposure conditions consistent with the exposure guidance values, may vary from the predicted average concentrations by several-fold due to within- and across-individual variation in urinary flow and creatinine excretion rates and due to the rapid elimination kinetics of fluoride. Thus, the BE values are most appropriately applied to screen population central tendency estimates for biomarker concentrations rather than interpretation of individual spot sample concentrations. Copyright © 2015. Published by Elsevier Inc.

FLUORIDE SORPTION USING MORRINGA INDICA-BASED ACTIVATED CARBON

Directory of Open Access Journals (Sweden)

G. Karthikeyan, S. Siva Ilango

2007-01-01

Full Text Available Batch adsorption experiments using activated carbon prepared from Morringa Indica bark were conducted to remove fluoride from aqueous solution. A minimum contact time of 25 min was required for optimum fluoride removal. The influence of adsorbent, dose, pH, co-ions (cations and anions on fluoride removal by the activated carbon has been experimentally verified. The adsorption of fluoride was studied at 30 C, 40 C and 50 C. The kinetics of adsorption and adsorption isotherms at different temperatures were studied. The fluoride adsorption obeyed both Langmuir and Freundlich isotherms and followed a pseudo first order kinetic model. The thermodynamic studies revealed that the fluoride adsorption by Morringa Indica is an endothermic process indicating an increase in sorption rate at higher temperatures. The negative values of G indicate the spontaneity of adsorption. SEM and XRD studies confirmed the surface morphological characteristics of the adsorbent and the deposition of fluoride on the surface of the material.

Localization of the antimony impurity atoms in the PbTe lattice determined by the Moessbauer emission spectroscopy

International Nuclear Information System (INIS)

Masterov, V.F.; Nasredinov, F.S.; Nemov, S.A.; Seregin, P.P.; Troitskaya, N.N.; Bondarevskij, S.I.

1997-01-01

The 119 Sb ( 119m Sn) emission Moessbauer spectroscopy has shown that a localization of the antimony impurity atoms in the PbTe lattice is affected by the conductivity type of the host material, the antimony atoms occupied mainly anion and cation sites in n-type and p-type samples, respectively. The 119 Sn impurity in the anion sublattice of PbTe formed an decay. Its charge state was shown to be independent of the Fermi level position

Effect of titanium tetrafluoride, amine fluoride and fluoride varnish on enamel erosion in vitro

NARCIS (Netherlands)

Vieira, A; Ruben, JL; Huysmans, MCDNJM

2005-01-01

This study aimed at evaluating the effect of 1 and 4% titanium tetrafluoride (TiF4) gels, amine fluoride (AmF) 1 and 0.25% and a fluoride varnish (FP) on the prevention of dental erosion. Two experimental groups served as controls, one with no pretreatment and another one pre-treated with a

Extraction-radiochemical study of the ion-association complex of antimony (V) with tetrazolium violet and its thermal behavior

International Nuclear Information System (INIS)

Kostova, S.G.; Boyanov, B.S.

1995-01-01

The optimum conditions for extraction of ion-associated complexes (IAS) formed from the tetrazolium salt - tetrazolium violet and Sb(V) in hydrochloric acid medium have been studied. An isotope of antimony ( 125 Sb) was used for determination of the recovery factor (R%) and distribution ratio (D S b). The thermal behavior of the antimony complex with tetrazole violet was studied using differential thermal and thermogravimetric analysis. (author) 12 refs.; 3 figs

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

4-phenylbutyrate Mitigates Fluoride-Induced Cytotoxicity in ALC Cells

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Maiko Suzuki

2017-05-01

Full Text Available Chronic fluoride over-exposure during pre-eruptive enamel development can cause dental fluorosis. Severe dental fluorosis is characterized by porous, soft enamel that is vulnerable to erosion and decay. The prevalence of dental fluorosis among the population in the USA, India and China is increasing. Other than avoiding excessive intake, treatments to prevent dental fluorosis remain unknown. We previously reported that high-dose fluoride induces endoplasmic reticulum (ER stress and oxidative stress in ameloblasts. Cell stress induces gene repression, mitochondrial damage and apoptosis. An aromatic fatty acid, 4-phenylbutyrate (4PBA is a chemical chaperone that interacts with misfolded proteins to prevent ER stress. We hypothesized that 4PBA ameliorates fluoride-induced ER stress in ameloblasts. To determine whether 4PBA protects ameloblasts from fluoride toxicity, we analyzed gene expression of Tgf-β1, Bcl2/Bax ratio and cytochrome-c release in vitro. In vivo, we measured fluorosis levels, enamel hardness and fluoride concentration. Fluoride treated Ameloblast-lineage cells (ALC had decreased Tgf-β1 expression and this was reversed by 4PBA treatment. The anti-apoptotic Blc2/Bax ratio was significantly increased in ALC cells treated with fluoride/4PBA compared to fluoride treatment alone. Fluoride treatment induced cytochrome-c release from mitochondria into the cytosol and this was inhibited by 4PBA treatment. These results suggest that 4PBA mitigates fluoride-induced gene suppression, apoptosis and mitochondrial damage in vitro. In vivo, C57BL/6J mice were provided fluoridated water for six weeks with either fluoride free control-chow or 4PBA-containing chow (7 g/kg 4PBA. With few exceptions, enamel microhardness, fluorosis levels, and fluoride concentrations of bone and urine did not differ significantly between fluoride treated animals fed with control-chow or 4PBA-chow. Although 4PBA mitigated high-dose fluoride toxicity in vitro, a diet

4-phenylbutyrate Mitigates Fluoride-Induced Cytotoxicity in ALC Cells.

Science.gov (United States)

Suzuki, Maiko; Everett, Eric T; Whitford, Gary M; Bartlett, John D

2017-01-01

Chronic fluoride over-exposure during pre-eruptive enamel development can cause dental fluorosis. Severe dental fluorosis is characterized by porous, soft enamel that is vulnerable to erosion and decay. The prevalence of dental fluorosis among the population in the USA, India and China is increasing. Other than avoiding excessive intake, treatments to prevent dental fluorosis remain unknown. We previously reported that high-dose fluoride induces endoplasmic reticulum (ER) stress and oxidative stress in ameloblasts. Cell stress induces gene repression, mitochondrial damage and apoptosis. An aromatic fatty acid, 4-phenylbutyrate (4PBA) is a chemical chaperone that interacts with misfolded proteins to prevent ER stress. We hypothesized that 4PBA ameliorates fluoride-induced ER stress in ameloblasts. To determine whether 4PBA protects ameloblasts from fluoride toxicity, we analyzed gene expression of Tgf -β 1, Bcl2 / Bax ratio and cytochrome-c release in vitro . In vivo , we measured fluorosis levels, enamel hardness and fluoride concentration. Fluoride treated Ameloblast-lineage cells (ALC) had decreased Tgf -β 1 expression and this was reversed by 4PBA treatment. The anti-apoptotic Blc2 / Bax ratio was significantly increased in ALC cells treated with fluoride/4PBA compared to fluoride treatment alone. Fluoride treatment induced cytochrome-c release from mitochondria into the cytosol and this was inhibited by 4PBA treatment. These results suggest that 4PBA mitigates fluoride-induced gene suppression, apoptosis and mitochondrial damage in vitro . In vivo , C57BL/6J mice were provided fluoridated water for six weeks with either fluoride free control-chow or 4PBA-containing chow (7 g/kg 4PBA). With few exceptions, enamel microhardness, fluorosis levels, and fluoride concentrations of bone and urine did not differ significantly between fluoride treated animals fed with control-chow or 4PBA-chow. Although 4PBA mitigated high-dose fluoride toxicity in vitro , a diet rich

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

Health effects of fluoride pollution caused by coal burning

Energy Technology Data Exchange (ETDEWEB)

Ando, M.; Tadano, M.; Yamamoto, S.; Tamura, K.; Chen, X. [Regional Environment Division, National Institute for Environmental Studies, Tsukuba, 305-0083 Ibaraki (Japan); Asanuma, S. [Japan Institute of Rural Medicine, Usuda, Nagano (Japan); Watanabe, T. [Saku Central Hospital, Usuda, Nagano (Japan); Kondo, T. [Matsumoto Dental College, Shiojiri, Nagano (Japan); Sakurai, S. [Otsuma Women' s University, Tama, Tokyo (Japan); Ji, R.; Liang, C.; Cao, S. [Institute of Environmental Health and Engineering, Beijing (China); Hong, Z. [Shanxi Maternity and Children' s Hospital, Taiyuan (China)

2001-04-23

Recently a huge amount of fluoride in coal has been released into indoor environments by the combustion of coal and fluoride pollution seems to be increasing in some rural areas in China. Combustion of coal and coal bricks is the primary source of gaseous and aerosol fluoride and these forms of fluoride can easily enter exposed food products and the human respiratory tract. Major human fluoride exposure was caused by consumption of fluoride contaminated food, such as corn, chilies and potatoes. For each diagnostic syndrome of dental fluorosis, a log-normal distribution was observed on the logarithm of urinary fluoride concentration in students in China. Urinary fluoride content was found to be a primary health indicator of the prevalence of dental fluorosis in the community. In the fluorosis areas, osteosclerosis in skeletal fluorosis patients was observed with a high prevalence. A biochemical marker of bone resorption, urinary deoxypyridinoline content was much higher in residents in China than in residents in Japan. It was suggested that bone resorption was stimulated to a greater extent in residents in China and fluoride may stimulate both bone resorption and bone formation. Renal function especially glomerular filtration rate was very sensitive to fluoride exposure. Inorganic phosphate concentrations in urine were significantly lower in the residents in fluorosis areas in China than in non-fluorosis area in China and Japan. Since airborne fluoride from the combustion of coal pollutes extensively both the living environment and food, it is necessary to reduce fluoride pollution caused by coal burning.

Health and ecological risk assessment of heavy metals pollution in an antimony mining region: a case study from South China.

Science.gov (United States)

Fei, Jiang-Chi; Min, Xiao-Bo; Wang, Zhen-Xing; Pang, Zhi-Hua; Liang, Yan-Jie; Ke, Yong

2017-12-01

In recent years, international research on the toxicity of the heavy metal, antimony, has gradually changed focus from early medical and pharmacological toxicology to environmental toxicology and ecotoxicology. However, little research has been conducted for sources identification and risk management of heavy metals pollution by long-term antimony mining activities. In this study, a large number of investigations were conducted on the temporal and spatial distribution of antimony and related heavy metal contaminants (lead, zinc, and arsenic), as well as on the exposure risks for the population for the Yuxi river basin in the Hunan province, China. The scope of the investigations included mine water, waste rock, tailings, agricultural soil, surface water, river sediments, and groundwater sources of drinking water. Health and ecological risks from exposure to heavy metal pollution were evaluated. The main pollution sources of heavy metals in the Yuxi River basin were analyzed. Remediation programs and risk management strategies for heavy metal pollution were consequently proposed. This article provides a scientific basis for the risk assessment and management of heavy metal pollution caused by antimony basin ore mining.

Deciphering lead and cadmium stripping peaks for porous antimony deposited electrodes

Directory of Open Access Journals (Sweden)

Taimoor Aqeel Ahmad

2016-06-01

Full Text Available Cadmium and lead are generally taken as model heavy metal ions in water to scale the detection limit of various electrode sensors, using electrochemical sensing techniques. These ions interact with the electrochemically deposited antimony electrodes depending on the diffusion limitations. The phenomenon acts differently for the in-situ and ex-situ deposition as well as for porous and non-porous electrodes. A method has been adopted in this study to discourage the stripping and deposition of the working ions (antimony to understand the principle of heavy metal ion detection. X-ray photoelectron spectroscopy (XPS technique was used to establish the interaction between the working and dissolved ions. In addition to the distinct peaks for each analyte, researchers also observed a shoulder peak. A possible reason for the presence of this peak was provided. Different electrochemical tests were performed to ascertain the theory on the basis of the experimental observations.

Thermodynamic properties of liquid silver-antimony alloys determined from emf measurements

International Nuclear Information System (INIS)

Krzyzak, Agnieszka; Fitzner, Krzysztof

2004-01-01

The thermodynamic properties of the liquid Ag-Sb alloys were determined using solid oxide galvanic cells with zirconia electrolyte. The emfs of the cells:Ag x Sb (1-x), Sb 2 O 3 /O 2- /airwere measured in the temperatures range 950-1100K in the whole range of the alloy compositions.First, the Gibbs free energy of formation of liquid Sb 2 O 3 from pure elements was derived:ΔG o f(Sb2O3) (J/mol)=-687100+243.23T.Next, the activities of antimony were measured as a function of the alloy compositions, x. Redlich-Kister polynomial expansion was used to describe the thermodynamic properties of the liquid phase. From the model equations the limiting value of the logarithm of activity coefficient of antimony in silver was obtained as a function of temperature:lnγ Sb 0 =-3812.5/T+0.4112.The obtained results were compared with the experimental values reported in the literature

Thermodynamic data-base for metal fluorides

Energy Technology Data Exchange (ETDEWEB)

Yoo, Jae Hyung; Lee, Byung Gik; Kang, Young Ho and others

2001-05-01

This study is aimed at collecting useful data of thermodynamic properties of various metal fluorides. Many thermodynamic data for metal fluorides are needed for the effective development, but no report of data-base was published. Accordingly, the objective of this report is to rearrange systematically the existing thermodynamic data based on metal fluorides and is to use it as basic data for the development of pyrochemical process. The physicochemical properties of various metal fluorides and metals were collected from literature and such existing data base as HSC code, TAPP code, FACT code, JANAF table, NEA data-base, CRC handbook. As major contents of the thermodynamic data-base, the physicochemical properties such as formation energy, viscosity, density, vapor pressure, etc. were collected. Especially, some phase diagrams of eutectic molten fluorides are plotted and thermodynamic data of liquid metals are also compiled. In the future, the technical report is to be used as basic data for the development of the pyrochemical process which is being carried out as a long-term nuclear R and D project.

Thermodynamic data-base for metal fluorides

International Nuclear Information System (INIS)

Yoo, Jae Hyung; Lee, Byung Gik; Kang, Young Ho and others

2001-05-01

This study is aimed at collecting useful data of thermodynamic properties of various metal fluorides. Many thermodynamic data for metal fluorides are needed for the effective development, but no report of data-base was published. Accordingly, the objective of this report is to rearrange systematically the existing thermodynamic data based on metal fluorides and is to use it as basic data for the development of pyrochemical process. The physicochemical properties of various metal fluorides and metals were collected from literature and such existing data base as HSC code, TAPP code, FACT code, JANAF table, NEA data-base, CRC handbook. As major contents of the thermodynamic data-base, the physicochemical properties such as formation energy, viscosity, density, vapor pressure, etc. were collected. Especially, some phase diagrams of eutectic molten fluorides are plotted and thermodynamic data of liquid metals are also compiled. In the future, the technical report is to be used as basic data for the development of the pyrochemical process which is being carried out as a long-term nuclear R and D project

Antimony to Cure Visceral Leishmaniasis Unresponsive to Liposomal Amphotericin B.

Directory of Open Access Journals (Sweden)

Gloria Morizot

2016-01-01

Full Text Available We report on 4 patients (1 immunocompetent, 3 immunosuppressed in whom visceral leishmaniasis had become unresponsive to (or had relapsed after treatment with appropriate doses of liposomal amphotericin B. Under close follow-up, full courses of pentavalent antimony were administered without life-threatening adverse events and resulted in rapid and sustained clinical and parasitological cure.

Metal fluoride complexes of Na,K-ATPase: characterization of fluoride-stabilized phosphoenzyme analogues and their interaction with cardiotonic steroids.

Science.gov (United States)

Cornelius, Flemming; Mahmmoud, Yasser A; Toyoshima, Chikashi

2011-08-26

The Na,K-ATPase belongs to the P-type ATPase family of primary active cation pumps. Metal fluorides like magnesium-, beryllium-, and aluminum fluoride act as phosphate analogues and inhibit P-type ATPases by interacting with the phosphorylation site, stabilizing conformations that are analogous to specific phosphoenzyme intermediates. Cardiotonic steroids like ouabain used in the treatment of congestive heart failure and arrhythmias specifically inhibit the Na,K-ATPase, and the detailed structure of the highly conserved binding site has recently been described by the crystal structure of the shark Na,K-ATPase in a state analogous to E2·2K(+)·P(i) with ouabain bound with apparently low affinity (1). In the present work inhibition, and subsequent reactivation by high Na(+), after treatment of shark Na,K-ATPase with various metal fluorides are characterized. Half-maximal inhibition of Na,K-ATPase activity by metal fluorides is in the micromolar range. The binding of cardiotonic steroids to the metal fluoride-stabilized enzyme forms was investigated using the fluorescent ouabain derivative 9-anthroyl ouabain and compared with binding to phosphorylated enzyme. The fastest binding was to the Be-fluoride stabilized enzyme suggesting a preformed ouabain binding cavity, in accord with results for Ca-ATPase where Be-fluoride stabilizes the E2-P ground state with an open luminal ion access pathway, which in Na,K-ATPase could be a passage for ouabain. The Be-fluoride stabilized enzyme conformation closely resembles the E2-P ground state according to proteinase K cleavage. Ouabain, but not its aglycone ouabagenin, prevented reactivation of this metal fluoride form by high Na(+) demonstrating the pivotal role of the sugar moiety in closing the extracellular cation pathway.

Molten fluoride fuel salt chemistry

International Nuclear Information System (INIS)

Toth, L.M.; Del Cul, G.D.; Dai, S.; Metcalf, D.H.

1995-01-01

The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed. copyright American Institute of Physics 1995

Milk fluoridation for the prevention of dental caries

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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.

Poisoning by coal smoke containing arsenic and fluoride

Energy Technology Data Exchange (ETDEWEB)

An, D.; He, Y.G.; Hu, Q.X. [Guizhou Sanitary and Epidemiological Station, Guiyang (China)

1997-02-01

An investigation was made into a disease involving skin pigmentation, keratosis of the hands and feet, dental discoloration, and generalized bone and joint pain, stiffness and rigidity, in the village of Bazhi, Zhijin County, Ghizhou Province, People`s Republic of China. Measurements were made of the arsenic and fluoride levels of coal, water, air, food, urine and hair in Bazhi and a control village, Xinzhai, in which coal with a low arsenic content was used. Up to 188 people, including children, in Bazhi and 752 in Xinzhai, were examined for the presence of chronic arsenium, skeletal fluorosis, dental fluorosis and electrocardiogram abnormalities. The coal in Bazhi was found to contain high levels of arsenic and fluoride resulting, after burning in homes without an adequate chimney systems, in pollution of air and food with arsenic and fluoride. The coal in Xinzhai did not cause arsenic pollution but did produce a higher level of fluoride pollution. It was concluded that the endemic disease in Bazhi was caused by pollution by coal smoke containing arsenic and fluoride. It is suggested that arsenic may act synergistically with fluoride so that a lower level of fluoride may produce fluoride toxicity with dental and skeletal fluorosis.

Dielectric Losses and Charge Transfer in Antimony-Doped TlGaS2 Single Crystal

Science.gov (United States)

Asadov, S. M.; Mustafaeva, S. N.

2018-03-01

Effect of semimetallic antimony (0.5 mol % Sb) on the dielectric properties and ac-conductivity of TlGaS2-based single crystals grown by the Bridgman-Stockbarger method has been studied. The experimental results on the frequency dispersion of dielectric coefficients and the conductivity of TlGa0.995Sb0.005S2 single crystals allowed the revealing of the dielectric loss nature, the charge transfer mechanism, and the estimation of the parameters of the states localized in the energy gap. The antimony-doping of the TlGaS2 single crystal leads to an increase in the density of states near the Fermi level and a decrease in the average time and average distance of hopes.

New Insight on the Response of Bacteria to Fluoride

Science.gov (United States)

Breaker, R.R.

2012-01-01

Fluoride has been used for decades to prevent caries and it is well established that this anion can inhibit the growth of bacteria. However, the precise effects that fluoride has on bacteria and the mechanisms that bacteria use to overcome fluoride toxicity have largely remained unexplored. Recently, my laboratory reported the discovery of biological systems that bacteria use to sense fluoride and reduce fluoride toxicity. These sensors and their associated genes are very widespread in biology, which has implications for a number of issues that are central to the use of fluoride for dental care. Below I provide a summary of our findings, comment on some of the key prospects for expanding our understanding of fluoride's effects on biology, and propose some future uses of this knowledge. PMID:22327376

New insight on the response of bacteria to fluoride.

Science.gov (United States)

Breaker, R R

2012-01-01

Fluoride has been used for decades to prevent caries and it is well established that this anion can inhibit the growth of bacteria. However, the precise effects that fluoride has on bacteria and the mechanisms that bacteria use to overcome fluoride toxicity have largely remained unexplored. Recently, my laboratory reported the discovery of biological systems that bacteria use to sense fluoride and reduce fluoride toxicity. These sensors and their associated genes are very widespread in biology, which has implications for a number of issues that are central to the use of fluoride for dental care. Below I provide a summary of our findings, comment on some of the key prospects for expanding our understanding of fluoride's effects on biology, and propose some future uses of this knowledge. Copyright © 2012 S. Karger AG, Basel.

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

Solubility and fluoride release in ionomers and compomers.

Science.gov (United States)

Bertacchini, S M; Abate, P F; Blank, A; Baglieto, M F; Macchi, R L

1999-03-01

The degree of solubility and the fluoride release of glass-ionomer cements and "compomers" were determined as a function of time. Three conventional glass-ionomer cements, three hybrid ionomers, and two compomers were included in the study. Disk-shaped specimens were prepared and immersed in a lactic acid solution. Solubility was evaluated from determinations of loss of mass as a function of time. To evaluate fluoride release, similar specimens were immersed in 50 mL of deionized water to which 50 mL of buffer solution was added. A fluoride ion detector was used to read the concentration of fluoride ion in the overall solution at different times after immersion. Material and time factors had a significant influence on results. The compomers showed less corrosion and fluoride release than the ionomers. Some correlation was found between solubility and fluoride leakage values. Components of both the ionomers and compomers that were studied can dissolve in water. The materials leak fluoride ions in amounts that differ according to the characteristics of the individual products.

Sustainable approach for recycling waste lamb and chicken bones for fluoride removal from water followed by reusing fluoride-bearing waste in concrete.

Science.gov (United States)

Ismail, Zainab Z; AbdelKareem, Hala N

2015-11-01

Sustainable management of waste materials is an attractive approach for modern societies. In this study, recycling of raw waste lamb and chicken bones for defluoridation of water has been estimated. The effects of several experimental parameters including contact time, pH, bone dose, fluoride initial concentration, bone grains size, agitation rate, and the effect of co-existing anions in actual samples of wastewater were studied for fluoride removal from aqueous solutions. Results indicated excellent fluoride removal efficiency up to 99.4% and 99.8% using lamb and chicken bones, respectively at fluoride initial concentration of 10 mg F/L and 120 min contact time. Maximum fluoride uptake was obtained at neutral pH range 6-7. Fluoride removal kinetic was well described by the pseudo-second order kinetic model. Both, Langmuir and Freundlich isotherm models could fit the experimental data well with correlation coefficient values >0.99 suggesting favorable conditions of the process. Furthermore, for complete sustainable management of waste bones, the resulted fluoride-bearing sludge was reused in concrete mixes to partially replace sand. Tests of the mechanical properties of fluoride sludge-modified concrete mixes indicated a potential environmentally friendly approach to dispose fluoride sludge in concrete and simultaneously enhance concrete properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antimony Trioxide (ATO) - Summary of External Peer Review and Public Comments and Disposition

Science.gov (United States)

This document summarizes the public and external peer review comments that the EPA’s Office of Pollution Prevention and Toxics (OPPT) received for the draft work plan risk assessment for Antimony Trioxide (ATO).

Mixing of phosphorus and antimony ions in silicon by recoil implantation

International Nuclear Information System (INIS)

Kwok, H.L.; Lam, Y.W.; Wong, S.P.; Poon, M.C.

1986-01-01

The effects of mixing phosphorus and antimony ions in silicon by recoil implantation were examined. The electrical properties after ion mixing were investigated, and the results were compared with those obtained using other techniques. Different degrees of activation were also studied, by investigating the annealing behaviour. (U.K.)

New Insight on the Response of Bacteria to Fluoride

OpenAIRE

Breaker, R.R.

2012-01-01

Fluoride has been used for decades to prevent caries and it is well established that this anion can inhibit the growth of bacteria. However, the precise effects that fluoride has on bacteria and the mechanisms that bacteria use to overcome fluoride toxicity have largely remained unexplored. Recently, my laboratory reported the discovery of biological systems that bacteria use to sense fluoride and reduce fluoride toxicity. These sensors and their associated genes are very widespread in biolog...

Widespread genetic switches and toxicity resistance proteins for fluoride.

Science.gov (United States)

Baker, Jenny L; Sudarsan, Narasimhan; Weinberg, Zasha; Roth, Adam; Stockbridge, Randy B; Breaker, Ronald R

2012-01-13

Most riboswitches are metabolite-binding RNA structures located in bacterial messenger RNAs where they control gene expression. We have discovered a riboswitch class in many bacterial and archaeal species whose members are selectively triggered by fluoride but reject other small anions, including chloride. These fluoride riboswitches activate expression of genes that encode putative fluoride transporters, enzymes that are known to be inhibited by fluoride, and additional proteins of unknown function. Our findings indicate that most organisms are naturally exposed to toxic levels of fluoride and that many species use fluoride-sensing RNAs to control the expression of proteins that alleviate the deleterious effects of this anion.

Influence of film thickness on structural, optical, and electrical properties of spray deposited antimony doped SnO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Yadav, Abhijit A., E-mail: aay_physics@yahoo.co.in

2015-09-30

Transparent conducting antimony doped SnO{sub 2} thin films with varying thickness were deposited by chemical spray pyrolysis technique from non-aqueous solvent Propan-2-ol. The effect of film thickness on the properties of antimony doped SnO{sub 2} thin films have been studied. X-ray diffraction measurements showed tetragonal crystal structure of as-deposited antimony doped SnO{sub 2} films irrespective of film thickness. The surface morphology of antimony doped SnO{sub 2} thin film is spherical with the continuous distribution of grains. Electrical and optical properties were investigated by Hall Effect and optical measurements. The average optical transmittance of films decreased from 89% to 73% within the visible range (350–850 nm) with increase in film thickness. The minimum value of sheet resistance observed is 4.81 Ω/cm{sup 2}. The lowest resistivity found is 3.76 × 10{sup −4} Ω cm at 660 nm film thickness. - Highlights: • Effect of film thickness on the properties of antimony doped SnO{sub 2} thin films • Crystalline size in the range of 34–37 nm • Average transmittance decreased from 89% to 73% in the visible region. • Minimum sheet resistance of 4.81 Ω/cm{sup 2} • Lowest resistivity is found to be 3.76 × 10{sup −4} Ω cm at 660 nm film thickness.

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.

Effect of antimony oxide on magnesium vanadates for the selective oxidation of hydrogen sulfide to sulfur

Energy Technology Data Exchange (ETDEWEB)

Li, K.T.; Chi, Z.H. [Department of Chemical Engineering, Tunghai University, ROC Taichung (Taiwan)

2001-05-17

The effect of antimony oxide addition to MgV{sub 2}O{sub 6} and Mg{sub 3}V{sub 2}O{sub 8} was studied in the selective oxidation of hydrogen sulfide to sulfur. Significant improvements in sulfur selectivity and yield were observed for the uncalcined mechanical mixtures of magnesium vanadates with {alpha}-Sb{sub 2}O{sub 4}. Calcination of the mechanical mixtures resulted in the much stronger synergy in catalytic activity and sulfur selectivity. For the uncalcined samples, XRD, TPR and XPS studies indicated that antimony reduction behaviors in the mechanical mixtures differed very much from those in {alpha}-Sb{sub 2}O{sub 4} alone, suggested that their selectivity improvements might be due to the interactions (probably oxygen transfer) between {alpha}-Sb{sub 2}O{sub 4} and magnesium vanadates. For the calcined samples, XRD results indicated that their better catalytic performances in H{sub 2}S oxidation were primarily attributed to the formation of VSbO{sub 4} compound from antimony oxide and magnesium vanadates.

Comparison of oral itraconazole and intramuscular meglumine antimoniate in the treatment of cutaneous leishmaniasis

International Nuclear Information System (INIS)

Saleem, K.; Rahman, A.

2007-01-01

To compare the efficacy and tolerability of oral itraconazole against intramuscular meglumine antimoniate in the treatment of Cutaneous Leishmaniasis (CL). Two hundred eligible and consenting patients of Cutaneous Leishmaniasis (CL) were divided in two groups with 100 patients in each. The number and location of the lesions were documented and clinical types of cutaneous leishmaniasis were noted. The diagnosis was confirmed by skin slit smear and histopathology of the lesional skin. Culture on Nicolle Novy MacNeal (NNN) medium and Leishmanin test was done in all patients. All the patients in both groups were subjected to complete blood picture, urine examination, serum urea and creatinine levels and ECG examination. One group was given itraconazole 100 mg twice daily orally for a duration of 6-8 weeks. The other group was given meglumine antimoniate 10 cc in the form of deep intramuscular injections for 15-30 days. The efficacy of the treatment was judged by clinical and parasitological response. Side effects of the agents were also noted during treatment. Out of 200 patients studied, 185 were males and 15 were females. The mean age of presentation was 30 + 6.6 years. Single lesion was seen in 132 (66%) subjects whereas 68 (34%) subjects had multiple lesions. Slit skin smears were positive in 50 (25%) of the patients. Skin biopsy yielded the presence of LT bodies in 150 (75%) subjects. The culture was positive in 102 (51%) cases. Leishmanin test was positive in 94% subjects. Seventy-five (75%) patients on itraconazole therapy showed complete clinical and parasitological cure in 4-8 weeks duration. A rise in ALT was seen in 12% subjects. Five (5%) subjects did not show any improvement till the end of therapy. Sixty-five (65%) subjects on meglumine antimoniate showed complete healing in 15-30 days. In 35 (35%) of the patients, the treatment had to be stopped due to intolerable side-effects. Four cases of lupoid leishmaniasis and 4 cases of sporotrichoid leishmaniasis

Risk perception, psychological heuristics and the water fluoridation controversy.

Science.gov (United States)

Perrella, Andrea M L; Kiss, Simon J

2015-04-29

Increasingly, support for water fluoridation has come under attack. We seek an explanation, focusing on the case of Waterloo, Ontario, where a 2010 referendum overturned its water fluoridation program. In particular, we test whether individuals perceive the risks of water fluoridation based not on 'hard' scientific evidence but on heuristics and cultural norms. A sample of 376 residents in Waterloo were surveyed in June 2012 using random digit dialing. We use factor analysis, OLS regression, as well as t-tests to evaluate a survey experiment to test the credibility hypothesis. Perceptions of fluoride as a risk are lower among those who perceive fluoride's benefits (B = .473, p < 0.001) and those whose cultural view is 'egalitarian' (B = .156, p < 0.05). The experiment shows a lower level of perception of fluoride's benefits among respondents who are told that water fluoridation is opposed by a national advocacy group (Group A) compared to those who are told that the government and the World Health Organization support fluoridation (Group B) (t = 1.6547, p < 0.05), as well as compared to the control group (t = 1.8913, p < 0.05). There is no difference between Group B and the control, possibly because people's already general support for fluoridation is less prone to change when told that other public organizations also support fluoridation. Public health officials should take into account cultural norms and perceptions when individuals in a community appear to rise up against water fluoridation, with implications for other public health controversies.

Antibacterial Effect of Silver Diamine Fluoride on Cariogenic Organisms.

Science.gov (United States)

Lou, Yali; Darvell, Brain W; Botelho, Michael G

2018-05-01

To screen the possible antimicrobial activity of a range of clinically used, silver-based compounds on cariogenic organisms: silver diamine fluoride (SDF), silver fluoride, and silver nitrate. Preliminary screening disk-diffusion susceptibility tests were conducted on Mueller-Hinton agar plates inoculated with Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces naeslundii, organisms known to be cariogenic. In order to identify which component of the silver compounds was responsible for any antibacterial (AB) effect, and to provide controls, the following were also investigated at high and low concentrations: sodium fluoride, ammonium fluoride, ammonium chloride, sodium fluoride, sodium chloride, and sodium nitrate, as well as deionized water as control. A volume of 10 pL of a test solution was dispensed onto a paper disk resting on the inoculated agar surface, and the plate incubated anaerobically at 37°C for 48 hours. The zones of inhibition were then measured. Silver diamine fluoride, silver fluoride, silver nitrate, and ammonium fluoride had significant AB effect (p effect at low concentration; the remaining other compounds had no effect. Silver ions appear to be the principal AB agent at both high and low concentration; fluoride ions only have an AB effect at high concentration, while ammonium, nitrate, chloride and sodium ions have none. The anticaries effect of topical silver solutions appears restricted to that of the silver ions. Silver compounds, such as SDF, silver fluoride, and silver nitrate have AB effect against cariogenic organisms and these may have clinical impact in arresting or preventing dental decay. Sodium fluoride did not have AB effect under the conditions tested.

High Fluoride Dentifrices for Elderly and Vulnerable Adults

DEFF Research Database (Denmark)

Ekstrand, Kim Rud

2016-01-01

The primary aim of this work is to present the available evidence that toothpastes containing >1,500 ppm fluoride (2,500-2,800 and 5,000 ppm F) provide an additional caries preventive effect on root caries lesions in elderly patients compared to traditional dentifrices (1,000-1,450 ppm F......). The secondary aim of this paper is to discuss why high fluoride dentifrices in general should perform better than traditional F-containing toothpaste. When examining the few studies that have considered the preventive benefits of high fluoride products on root caries the relative risk appears to be around 0.......5, and the risk can thus be halved by exchanging traditional F-containing toothpaste for toothpaste containing 5,000 ppm F. There is reasonable evidence that high fluoride dentifrices significantly increase the fluoride concentration in saliva during the day and the fluoride concentration in plaque compared...

Approaches to the accurate characterization of high purity metal fluorides and fluoride glasses

Science.gov (United States)

Beary, E. S.; Paulsen, P. J.; Rains, T. C.; Ewing, K. J.; Jaganathan, J.; Aggarwal, I.

1990-11-01

The analytical challenges posed by the measurement of trace contaminants in high purity metal fluorides require that innovative chemical preparation procedures be used to enhance existing instrumental techniques. The instrumental techniques used to analyze these difficult matrices must be sensitive enough to detect extremely low levels of trace impurities, and the background interferences derived from the matrix (metal fluoride or glass) must be minimized. A survey of analytical techniques that have the necessary characteristics to analyze these materials will be given. In addition, means of controlling the chemical blank will be presented. Mass and atomic spectrometric techniques will be discussed, specifically graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma-mass spectrometry (ICP-MS). Analytical procedures using GFAAS and ICP-MS have been developed to determine sub ppb (part per billion) levels of contaminants in high purity fluoride materials.

A facile and fast route to prepare antimony (Sb) nanostructures without additives

KAUST Repository

Shah, M.A.

2011-01-01

is based on a reaction of antimony powder and pure water at ∼210 °C without using any harmful additives and amines. The XRD pattern confirmed the composition and crystallinity of the grown nanostructures. The reported method besides being organics free

A facile and fast route to prepare antimony (Sb) nanostructures without additives

KAUST Repository

Shah, M.A.

2011-12-01

Herein, we report a safe, low cost and reproducible approach for the synthesis of antimony (Sb) nanostructures with most of them having prism like morphology and having well defined faces in the range of ∼70210 nm. The organics free approach is based on a reaction of antimony powder and pure water at ∼210 °C without using any harmful additives and amines. The XRD pattern confirmed the composition and crystallinity of the grown nanostructures. The reported method besides being organics free is economical, fast and free of pollution, which will make it suitable for large scale production. Furthermore, it is well expected that such a technique could be extended to prepare many other important metal and metal oxide nanostructures. The prospects of the process are bright and promising. © 2012 Sharif University of Technology. Production and hosting by Elsevier B.V. All rights reserved.

Antimony Influence on Shape of Eutectic Silicium in Al-Si Based Alloys

Directory of Open Access Journals (Sweden)

Bolibruchová D.

2017-12-01

Full Text Available Liquid AI-Si alloys are usually given special treatments before they are cast to obtain finer or modified matrix and eutectic structures, leading to improved properties. For many years, sodium additions to hypoeutectic and eutectic AI-Si melts have been recognized as the most effective method of modifying the eutectic morphology, although most of the group IA or IIA elements have significant effects on the eutectic structure. Unfortunately, many of these approaches also have associated several founding difficulties, such as fading, forming dross in presence of certain alloying elements, reduced fluidity, etc. ln recent years, antimony additions to AI-Si castings have attracted considerable attention as an alternative method of refining the eutectic structure. Such additions eliminate many of the difficulties listed above and provide permanent (i.e. non-fading refining ability. In this paper, the authors summarize work on antimony treatment of Al-Si based alloys.

Adsorption and exhaustion device for gaseoue uranium fluorides

International Nuclear Information System (INIS)

Kida, Yasuo; Nakamura, Yuichi.

1984-01-01

Purpose: To prevent gaseous uranium fluorides from passing through the adsorption layer upon exhausting the gaseous uranium, fluorides from a uranium fluoride processing facility through adsorption traps, by controlling the flow rate of the gaseous uranium fluorides passing through the layer constant. Constitution: An adsorption trap is connected by way of pipeways to a uranium fluoride processing facility, and a flow rate detector for detecting the flow rate of gaseous uranium fluorides and a pressure gauge for detecting the pressure at the inlet of the adsorption trap are disposed to the pipeways. The setting value for the pressure control is calculated from the detection value of the flow rate detector by the pressure control gage. Then, an operation amount for the pressure control valve is calculated based on the deviatoin between the setting value for the pressure control and the inlet pressure at the adsorption trap. This enables to control the flow rate of the gaseous uranium fluorides passing through the adsorption layer always constant thereby enabling to prevent excess increase in the flow rate which results in damages in the adsorption layer. (Moriyama, K.)

The effective use of fluorides in public health

DEFF Research Database (Denmark)

Jones, Sheila; Burt, Brian A; Petersen, Poul Erik

2005-01-01

, systematic reviews summarizing these extensive databases have indicated that water fluoridation and fluoride toothpastes both substantially reduce the prevalence and incidence of dental caries. We present four case studies that illustrate the use of fluoride in modern public health practice, focusing on......Dental caries remain a public health problem for many developing countries and for underprivileged populations in developed countries. This paper outlines the historical development of public health approaches to the use of fluoride and comments on their effectiveness. Early research...

Absorption, distribution and excretion of inhaled hydrogen fluoride in the rat

Energy Technology Data Exchange (ETDEWEB)

Morris, J.B.

1979-01-01

Rats were subjected to whole body HF exposure for 6 hrs or to nose-only HF exposure for 1 hr. Total and/or ionic fluoride concentrations in selected tissues were determined at various times following exposure. In rats sacrificed 6 hrs after whole body exposure, dose-dependent increases in lung, plasma, and kidney total and ionic fluoride concentration occurred. Rats excreted more fluoride in the urine after whole body exposure than could be explained by the amount of HF inhaled. Considerable evidence suggests that airborne HF deposits on fur and is then ingested due to preening activity. Urinary fluoride excretion was increased by nose-only exposure. The urinary fluoride excretion accounted for approximately twice the fluoride estimated to be inhaled during exposure. Tissue fluoride concentrations were elevated immediately after nose-only exposure. Fluoride concentrations in lung and kidney returned to control levels within 12 hrs. Plasma fluoride concentration was slightly elevated 24 hrs after the start of the 1 hr exposure but was at control levels at 96 hrs. Immediately following nose-only exposure, lung ionic fluoride concentrations were less than plasma ionic fluoride concentrations suggesting that the fluoride in the lung had reached that site via plasma transport rather than by inhalation. A dose-dependent increase in plasma ionic fluoride concentration occurred after upper respiratory tract HF exposure providing strong evidence that fluoride is absorbed systemically from that site. The plasma ionic fluoride concentration after upper respiratory tract exposure was of sufficient magnitude to account for the plasma fluoride concentrations observed in intact nose-only exposed rats. (ERB)

Preconcentration of ultra-trace amounts of iron and antimony using ion pair solid phase extraction with modified multi-walled carbon nanotubes

International Nuclear Information System (INIS)

Fazelirad, Hamid; Taher, Mohammad Ali

2014-01-01

Ion pair solid phase extraction was applied to the simultaneous preconcentration of iron and antimony. The ion pairs consisting of FeCl 4 − or SbCl 4 − anions and the benzyldimethyltetradecyl ammonium cation were formed on the surface of multi-walled carbon nanotubes, then eluted with nitric acid, and the elements finally quantified by ETAAS. The adsorption capacities of the impregnated MWCNTs are 9.2 mg g −1 for iron and 27.5 mg g −1 for antimony. The following analytical figures of merit were determined for iron and antimony, respectively: Enrichment factors of 210 and 230, assay precisions of ±5.3 % and ±4.8 %, linear calibration plots from 0.7 to 9.4 and 13.0 to 190 ng L −1 , and detection limits of 0.17 and 3.5 ng L −1 . The method was applied to the determination of iron and antimony in human hair, synthetic sample, and to the certified reference materials gold ore (MA-1b) and trace elements in water (SRM 1643d). (author)

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.

Fluoridation Basics

Science.gov (United States)

... return on investment for community water fluoridation (including productivity losses) ranged from $4 in small communities of ... National Center for Chronic Disease Prevention and Health Promotion Email Recommend Tweet YouTube Instagram Listen Watch RSS ...

Fluoride removal performance of phosphoric acid treated lime ...

African Journals Online (AJOL)

Fluoride in drinking water above permissible levels is responsible for dental and skeletal fluorosis. In this study, removal of fluoride ions from water using phosphoric acid treated lime was investigated in continuous and point-of-use system operations. In the continuous column operations, fluoride removal performance was ...

Determination of concentration levels of arsenic, gold and antimony in particle-size fractions of gold ore using Neutron Activation Analysis

International Nuclear Information System (INIS)

Nyarku, M.

2009-02-01

Instrumental Neutron Activation Analysis (INAA) has been used to quantify the concentrations of arsenic, gold and antimony in particle-size fractions of a gold ore. The ore, which was taken from the Ahafo project site of Newmont Ghana Gold Ltd, was first fractionated into fourteen (14) particle-size fractions using state-of-the-art analytical sieve machine. The minimum sieve mesh size used was 36 microns and grains >2000 microns were not considered for analysis. Results of the sieving were analysed with easysieve software. The < 36 microns sub fraction was found to be the optimum, hosting bulk of all three elements. For arsenic, the element was found to be highly concentrated in < 36 to +100 microns size fractions and erratically distributed from +150 microns fraction and above. For gold, in exception of the sub fraction <36 which had exceptionally high concentration, the element is distributed in all the size fractions but slightly 'plays out' in the +150 to +400 microns fractions. Antimony occurrence in the sample was relatively high in <36 microns size fraction followed by 600 - 800, 800 - 1000, 400 - 600 and 36 - 40 microns size fractions in that order. Gold content in the sample was far higher than that of arsenic and antimony. Gold concentration in the composite sample was in the range 564 - 8420 ppm. Arsenic levels were higher as compared to antimony. The range of arsenic concentration in the composite sample was 14.33 - 186.92 ppm. Antimony concentration was in the range 1.09 - 9.48 ppm. (au)

Fluoride uptake from restorative dental materials by human enamel

International Nuclear Information System (INIS)

Forsten, L.; Rytoemaa, I.; Anttila, A.; Keinonen, J.

1976-01-01

The purpose of the study was to determine the uptake in vitro of fluoride from restorative materials by tooth enamel and whether prior etching of the enamel causes a change of uptake. The outermost layer of the labial surface of extracted canines was removed by grinding and the enamel was covered with five different fluoride-containing materials ; a silicate, a composite resin, an amalgam, a silicophosphate, and a polycarboxylate luting cement. The material was either removed immediately or after storing the tooth in distilled water. The fluoride content was determined using a sensitive physical method based on the 19 F (p, αγ) 16 O reaction. In addition, the fluoride content of enamel after etching for different periods of time and of etched enamel which had been in contact with silicate cement was determined. The mean fluoride content of uncovered interior enamel was 226 parts 10 6 . All materials, except the composite, increased clearly the fluoride content of the underlying enamel. Etching of interior enamel also increased the fluoride values. No difference could be shown in fluoride uptake from silicate and composite resin between etched and unetched enamel. (author)

Chronic exposure to arsenic in drinking water can lead to resistance to antimonial drugs in a mouse model of visceral leishmaniasis.

Science.gov (United States)

Perry, Meghan R; Wyllie, Susan; Raab, Andrea; Feldmann, Joerg; Fairlamb, Alan H

2013-12-03

The Indian subcontinent is the only region where arsenic contamination of drinking water coexists with widespread resistance to antimonial drugs that are used to treat the parasitic disease visceral leishmaniasis. We have previously proposed that selection for parasite resistance within visceral leishmaniasis patients who have been exposed to trivalent arsenic results in cross-resistance to the related metalloid antimony, present in the pentavalent state as a complex in drugs such as sodium stibogluconate (Pentostam) and meglumine antimonate (Glucantime). To test this hypothesis, Leishmania donovani was serially passaged in mice exposed to arsenic in drinking water at environmentally relevant levels (10 or 100 ppm). Arsenic accumulation in organs and other tissues was proportional to the level of exposure and similar to that previously reported in human liver biopsies. After five monthly passages in mice exposed to arsenic, isolated parasites were found to be completely refractory to 500 μg · mL(-1) Pentostam compared with the control passage group (38.5 μg · mL(-1)) cultured in vitro in mouse peritoneal macrophages. Reassessment of resistant parasites following further passage for 4 mo in mice without arsenic exposure showed that resistance was stable. Treatment of infected mice with Pentostam confirmed that resistance observed in vitro also occurred in vivo. We conclude that arsenic contamination may have played a significant role in the development of Leishmania antimonial resistance in Bihar because inadequate treatment with antimonial drugs is not exclusive to India, whereas widespread antimonial resistance is.

Structural, magnetic and dielectric investigations in antimony doped nano-phased nickel-zinc ferrites

Energy Technology Data Exchange (ETDEWEB)

Lakshmi, Ch.S. [Department of Physics, Regency Institute of Technology, Adivipolam Yanam 533464, Pondicherry (India); Sridhar, Ch.S.L.N. [Department of Physics, Vignana Bharathi Institute of Technology, Aushapur(v) Ghatkesar (M), Hyderabad 501301, Telangana (India); Govindraj, G. [Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, R.V.Nagar, Kalapet, Pondicherry 605014 (India); Bangarraju, S. [Department of Physics, Andhra University, Visakhapatnam 530003, Andhrapradesh (India); Potukuchi, D.M., E-mail: potukuchidm@yahoo.com [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University:Kakinada, Kakinada 533003 (India)

2015-02-15

Nanocrystalline Ni–Zn–Sb ferrites synthesized by hydrothermal method are reported. Influence of Sb{sup 5+} ions on structural, magnetic and dielectric properties of ferrites is studied. Phase identification, lattice parameter and crystallite size studies are carried out using by X-ray diffraction (XRD). Addition of dopant resulted for decrease in lattice parameter. Crystallite size gets reduced from 62 nm to 38 nm with doping of Antimony. Crystallite size and porosity exhibit similar trends with doping. Morphological study is carried out by Field Emission Scanning Electron Microscopy (FESEM). Strong FTIR absorption bands at 400–600 cm{sup −1} confirm the formation of ferrite structure. Increase of porosity is attributed to the grain size. Doping with Antimony results for decrease in saturation magnetization and increase in coercivity. An initial increase of saturation magnetization for x=0.1 is attributed to the unusually high density. Reversed trend of coercivity with crystallite size are observed. Higher value of dielectric constant ε′(ω) is attributed to the formation of excess of Fe{sup 2+} ions caused by aliovalent doping of Sb{sup 5+} ions. Variation of dielectric constant infers hopping type of conductivity mechanism. The dielectric loss factor tanδ attains lower values of ∼10{sup −2}. High ac resistivity ρ(ω) of 10{sup 8} Ω cm is witnessed for antimony doped ferrites. Higher saturation magnetization and enhanced dielectric response directs for a possible utility as microwave oscillators and switches.

Fluoride ion recognition by chelating and cationic boranes.

Science.gov (United States)

Hudnall, Todd W; Chiu, Ching-Wen; Gabbaï, François P

2009-02-17

Because of the ubiquity of fluoride ions and their potential toxicity at high doses, researchers would like to design receptors that selectively detect this anion. Fluoride is found in drinking water, toothpaste, and osteoporosis drugs. In addition, fluoride ions also can be detected as an indicator of uranium enrichment (via hydrolysis of UF(6)) or of the chemical warfare agent sarin, which releases the ion upon hydrolysis. However, because of its high hydration enthalpy, the fluoride anion is one of the most challenging targets for anion recognition. Among the various recognition strategies that are available, researchers have focused a great deal of attention on Lewis acidic boron compounds. These molecules typically interact with fluoride anions to form the corresponding fluoroborate species. In the case of simple triarylboranes, the fluoroborates are formed in organic solvents but not in water. To overcome this limitation, this Account examines various methods we have pursued to increase the fluoride-binding properties of boron-based receptors. We first considered the use of bifunctional boranes, which chelate the fluoride anion, such as 1,8-diborylnaphthalenes or heteronuclear 1-boryl-8-mercurio-naphthalenes. In these molecules, the neighboring Lewis acidic atoms can cooperatively interact with the anionic guest. Although the fluoride binding constants of the bifunctional compounds exceed those of neutral monofunctional boranes by several orders of magnitude, the incompatibility of these systems with aqueous media limits their utility. More recently, we have examined simple triarylboranes whose ligands are decorated by cationic ammonium or phosphonium groups. These cationic groups increase the electrophilic character of these boranes, and unlike their neutral analogs, they are able to complex fluoride in aqueous media. We have also considered cationic boranes, which form chelate complexes with fluoride anions. Our work demonstrates that Coulombic and chelate

Mechanisms of antimony adsorption onto soybean stover-derived biochar in aqueous solutions

Science.gov (United States)

Limited mechanistic knowledge is available to understand how biochar interacts with trace elements that exist predominantly as oxoanions, such as antimony (Sb). Soybean stover biochars were produced at 300 degrees C (SBC300) and 700 degrees C (SBC700), and were characterized by BET, Boehm titration,...

Fluoride reactions with dental enamel following different forms of fluoride supply

International Nuclear Information System (INIS)

Hellstroem, I.; Ericsson, Y.

1976-01-01

The reactions with dental enamel of NaF as tablets dissolved in different beverages or supplied with NaCl, simulating domestic salt fluoridation, were studied in tests with enamel surfaces and enamel powder. It was confirmed that powdered enamel can react quite differently from enamel surfaces under certain conditions. Enamel surfaces took up much more fluoride (F) from orange juice than from water or milk, and neither the low pH nor the citrate content of the juice increased the formation of unstable CaF 2 in the enamel, as judged from a KOH leaching test. The F uptake by enamel surfaces from 0.25 mM NaF in 175 mM NaCl, corresponding to a dish prepared with salt containing 500 parts/10 6 F, was about 80 percent greater than from the same NaF concentration in water. This NaCl concentration did not increase the formation of CaF 2 in the enamel, as judged from the KOH test, while 350 mM NaCl caused a moderate increase. The investigations support the administration of NaF tablets with orange juice and the plans for domestic salt fluoridation. (author)

Growth of antimony doped P-type zinc oxide nanowires for optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhong Lin; Pradel, Ken

2016-09-27

In a method of growing p-type nanowires, a nanowire growth solution of zinc nitrate (Zn(NO.sub.3).sub.2), hexamethylenetetramine (HMTA) and polyethylenemine (800 M.sub.w PEI) is prepared. A dopant solution to the growth solution, the dopant solution including an equal molar ration of sodium hydroxide (NaOH), glycolic acid (C.sub.2H.sub.4O.sub.3) and antimony acetate (Sb(CH.sub.3COO).sub.3) in water is prepared. The dopant solution and the growth solution combine to generate a resulting solution that includes antimony to zinc in a ratio of between 0.2% molar to 2.0% molar, the resulting solution having a top surface. An ammonia solution is added to the resulting solution. A ZnO seed layer is applied to a substrate and the substrate is placed into the top surface of the resulting solution with the ZnO seed layer facing downwardly for a predetermined time until Sb-doped ZnO nanowires having a length of at least 5 .mu.m have grown from the ZnO seed layer.

Fluoride use in Controlling Dental Caries and Fluorosis

Directory of Open Access Journals (Sweden)

Gaurav Solanki

2012-07-01

Full Text Available Policy were introduced to control fluoride exposure and to reduce the prevalence of fluorosis. The study aimed of describing the prevalence, severity and risk factors for fluorosis, and to describe the trend of fluorosis among Indian children. The study also aimed of exploring the effect of the change in fluoride exposure on dental fluorosis and caries. Establishing an appropriate use of fluoride toothpaste could be successful in reducing fluorosis without a significant increase in caries experience. The use of fluorides for oral health has always involved a balance between the protective benefit against dental caries and the risk of developing fluorosis. The link between fluoride and dental health was established to determining the causes of dental fluorosis or enamel mottling. Fluorosis in Indian children was highly prevalent in the early 1990s.

Fluoride remediation using floating macrophytes

Directory of Open Access Journals (Sweden)

Naba Kumar Mondal

2014-04-01

Full Text Available Six aquatic macrophytes, such as Pistia stratiotes, Ceratophyllum demersum, Nymphoides indica, Lemna major, Azolla pinnata,and Eichhornia crassipes were considered for remove fluoride from aqueous solution. Five different concentrations (10, 30, 50, and 100 ppm of fluoride solution were taken in 1 L plastic container. Fixed weight (20 g of macrophytes along with 500 ml fluoride solution was taken in each plastic container for 72 hours observation. Results demonstrated all the macrophytes show highest fluoride removal during 24 h to 48 h, but after 72 h their efficiency reduced drastically. The species N. indica showed better removal efficiency than other experimental macrophytes. In general, pigment measurement data indicated higher concentration at 72 h. However, Pistia sp. showed higher concentration of pigmentation at intermediate time interval (48 h. Higher level of dry weight to fresh weight ratio was recorded for L. major and A. pinnata at all concentrations, excepting at 10 ppm. In addition, all macrophytes showed lower RGR at higher concentration. Isotherm study indicated that macrophyte C. demersum is a good fitted with Freundlich and Langmuir isotherm whereas L. major with Langmuir isotherm during 24 hours.

pH-regulated antimony oxychloride nanoparticle formation on titanium oxide nanostructures: a photocatalytically active heterojunction

KAUST Repository

Buchholcz, Balázs

2017-02-06

Improving the catalytic activity of heterogeneous photocatalysts has become a hot topic recently. To this end, considerable progress has been made in the efficient separation of photogenerated charge carriers by e.g. the realization of heterojunction photocatalysts. V-VI-VII compound semiconductors, namely, bismuth oxyhalides, are popular photocatalysts. However, results on antimony oxyhalides [SbOX (X = Br, Cl, I)], the very promising alternatives to the well-known BiOX photomodifiers, are scarce. Here, we report the successful decoration of titanium oxide nanostructures with 8-11 nm diameter SbOX nanoparticles for the first time ever. The product size and stoichiometry could be controlled by the pH of the reactant mixture, while subsequent calcination could transform the structure of the titanate nanotube (TiONT) support and the prepared antimony oxychloride particles. In contrast to the ease of composite formation in the SbOX/TiONT case, anatase TiO could not facilitate the formation of antimony oxychloride nanoparticles on its surface. The titanate nanotube-based composites showed activity in a generally accepted quasi-standard photocatalytic test reaction (methyl orange dye decolorization). We found that the SbOCl/TiONT synthesized at pH = 1 is the most active sample in a broad temperature range.

Density and surface tension of melts of zirconium and hafnium fluorides with lithium fluoride

International Nuclear Information System (INIS)

Katyshev, S.F.; Artemov, V.V.; Desyatnik, V.N.

1988-01-01

A study was conducted to determine the temperature dependence of the density and surface tension of melts of LiF-ZrF 4 and LiF-HfF 4 . Density and surface tension were determined by the method of maximum pressure in an argon bubble. On the basis of experimental data over the entire concentration range the molar volumes and their relative deviations from the additive molar volumes were calculated for 1100 0 K. The positive deviations of the molar volumes from additivity in the LiF-HfF 4 system (22.45%) were greater than in the LiF-ZrF 4 system (15.75%). This indicated that the reaction with lithium fluoride is intensified with the switch to the hafnium fluoride. Results also demonstrated that the fluorides are surface-active components in the molten mixtures

Determination of antimony compounds in waters and juices using ion chromatography-inductively coupled plasma mass spectrometry.

Science.gov (United States)

Lin, Ya-An; Jiang, Shiuh-Jen; Sahayam, A C

2017-09-01

A method was developed by coupling ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS) for the speciation of antimony. In this study, antimony species such as antimonite [Sb(III)], antimonate [Sb(V)] and trimethyl antimony(V) (TMeSb) were separated in less than 8min using anion exchange chromatography with a Hamilton PRP-X100 column as the stationary phase. Mobile phase A was 20mmolL -1 ethylenediaminetetraacetic acid (EDTA), 2mmolL -1 potassium hydrogen phthalate (KHP) in 1% v/v methanol (pH 5.5) and 20mmolL -1 EDTA, 2mmolL -1 KHP, 40mmolL -1 (NH 4 ) 2 CO 3 in 1% v/v methanol (pH 9.0) formed mobile phase B. Detection limits and relative standard deviations (RSD) were 0.012-0.032ngmL -1 and 2.2-2.8% respectively. This method was applied to bottled waters and fruit juices purchased in Kaohsiung, Taiwan. In water samples, Sb(V) was the major species where as in juices organometallic Sb species were also present. Copyright © 2017 Elsevier Ltd. All rights reserved.

Differences in antimony and arsenic releases from lead smelter fly ash in soils

Czech Academy of Sciences Publication Activity Database

Ettler, V.; Mihaljevič, M.; Šebek, O.; Valigurova, R.; Klementová, Mariana

2012-01-01

Roč. 72, Supp. 4 (2012), s. 15-22 ISSN 0009-2819 Institutional research plan: CEZ:AV0Z40320502 Keywords : Antimony * Arsenic * Lead smelting * Fly ash * Soil * Mobility Subject RIV: CA - Inorganic Chemistry Impact factor: 1.351, year: 2012

Polymorphism and properties of Bi{sub 2}WO{sub 6} doped with pentavalent antimony

Energy Technology Data Exchange (ETDEWEB)

Kharitonova, E.P.; Belov, D.A. [M.V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Gagor, A.B.; Pietraszko, A.P. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-950 Wrocław (Poland); Alekseeva, O.A. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow (Russian Federation); Voronkova, V.I., E-mail: voronk@polly.phys.msu.ru [M.V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation)

2014-04-05

Highlights: • The limit of Bi{sub 2}W{sub 1−x}Sb{sub x}O{sub 6−y} solid solutions is at x = 0.05. • Bi{sub 2}W{sub 1−x}Sb{sub x}O{sub 6−y} does not fully transform into high-temperature monoclinic phase. • Sb{sup 5+} has a weak effect on the temperatures of the ferroelectric transitions. • γ→γ{sup ‴} transition near 650 °C was observed as strong permittivity peak at 0.01–8 Hz. • The conductivity of Bi{sub 2}W{sub 0.96}Sb{sub 0.04}O{sub 6−y} at 800 °C reaches 0.02 S/cm. -- Abstract: Antimony-containing solid solutions isostructural with bismuth tungstate, Bi{sub 2}WO{sub 6}, have been prepared in air as polycrystalline samples by solid-state reactions and as single crystals by unseeded flux growth. The antimony in the solid solutions is in a pentavalent state and substitutes for tungsten in the structure of Bi{sub 2}WO{sub 6}. The Bi{sub 2}W{sub 1−x}Sb{sub x}O{sub 6−y} solid solutions have been shown to exist in the composition range 0 ⩽ x ⩽ 0.05. We have examined the effect of Sb{sup 5+} doping on the polymorphism and properties of Bi{sub 2}WO{sub 6}. In contrast to undoped Bi{sub 2}WO{sub 6}, antimony-substituted bismuth tungstate does not completely transform into its high-temperature, monoclinic phase at 960 °C and remains two-phase up to temperatures approaching its melting point. Antimony substitution for tungsten has a weak effect on the temperatures of the ferroelectric phase transitions. Heterovalent substitution of Sb{sup 5+} for W{sup 6+} is accompanied by the formation of extra oxygen vacancies and an increase in the electrical conductivity of the solid solutions by one to two orders of magnitude relative to undoped Bi{sub 2}WO{sub 6}.

Coprecipitation of iron and silver with barium fluoride

International Nuclear Information System (INIS)

Kopilova, N.V.; Khamidov, B.O.; Kashina, Z.A.; Ikrami, D.D.

1986-01-01

Distribution of trace contaminants of iron and silver at coprecipitation of barium fluoride is studied in present work. It is defined that iron almost completely coprecipitated with barium fluoride in wide range of ph 5.5-12. Silver coprecipitated with barium fluoride in ph range 4-7. The value of coprecipitation varies from 94% to 100%.

Improvement of hydrogen storage kinetics in ball-milled magnesium doped with antimony

Czech Academy of Sciences Publication Activity Database

Čermák, Jiří; Král, Lubomír; Roupcová, Pavla

2017-01-01

Roč. 42, č. 9 (2017), s. 6144-6151 ISSN 0360-3199 R&D Projects: GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : Hydrogen * Hydrogen storage * Storage capacity * Magnesium alloys * Antimony Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering Impact factor: 3.582, year: 2016

Data on fluoride concentration level in villages of Asara (Alborz, Iran) and daily fluoride intake based on drinking water consumption.

Science.gov (United States)

Akhavan, Giti; Dobaradaran, Sina; Borazjani, Jaleh Mohajeri

2016-12-01

In the present data article, fluoride concentration levels of drinking water (with spring or groundwater sources) in 10 villages of Asara area located in Alborz province were determined by the standard SPADNS method using a spectrophotometer (DR/2000 Spectrophotometer, USA). Daily fluoride intakes were also calculated based on daily drinking water consumption. The fluoride content were compared with EPA and WHO guidelines for drinking water.

ADSORPTIVE REMOVAL OF FLUORIDE FROM WATER USING ...

African Journals Online (AJOL)

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Currently available treatment methods for removal of excess fluoride from water are broadly divided into three ... the application of nanoparticles as sorbents for fluoride removal. Sundaram [26] studied the ... Characterization of adsorbent.

Process development for treatment of fluoride containing wastes

Energy Technology Data Exchange (ETDEWEB)

Singh, Mahesh; Kanvinde, V Y [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

Many chemical and metallurgical industries generate liquid wastes containing high values of fluorides in association of nitrates and other metals. Due to harmful effects of fluorides these type of wastes can not be disposed off in the environment without proper treatment. Bench-scale laboratory experiments were conducted to develop a process scheme to fix the fluorides as non-leachable solid waste and fluoride free treated liquid waste for their disposal. To optimize the important parameters, simulated synthetic and actual wastes were used. For this study, three waste streams were collected from Nuclear Fuel Complex, Hyderabad. (author). 6 tabs., 1 fig.

Toxicity of fluoride to microorganisms in biological wastewater treatment systems.

Science.gov (United States)

Ochoa-Herrera, Valeria; Banihani, Qais; León, Glendy; Khatri, Chandra; Field, James A; Sierra-Alvarez, Reyes

2009-07-01

Fluoride is a common contaminant in a variety of industrial wastewaters. Available information on the potential toxicity of fluoride to microorganisms implicated in biological wastewater treatment is very limited. The objective of this study was to evaluate the inhibitory effect of fluoride towards the main microbial populations responsible for the removal of organic constituents and nutrients in wastewater treatment processes. The results of short-term batch bioassays indicated that the toxicity of sodium fluoride varied widely depending on the microbial population. Anaerobic microorganisms involved in various metabolic steps of anaerobic digestion processes were found to be very sensitive to the presence of fluoride. The concentrations of fluoride causing 50% metabolic inhibition (IC(50)) of propionate- and butyrate-degrading microorganisms as well as mesophilic and thermophilic acetate-utilizing methanogens ranged from 18 to 43 mg/L. Fluoride was also inhibitory to nitrification, albeit at relatively high levels (IC(50)=149 mg/L). Nitrifying bacteria appeared to adapt rapidly to fluoride, and a near complete recovery of their metabolic activity was observed after only 4d of exposure to high fluoride levels (up to 500 mg/L). All other microbial populations evaluated in this study, i.e., glucose fermenters, aerobic glucose-degrading heterotrophs, denitrifying bacteria, and H(2)-utilizing methanogens, tolerated fluoride at very high concentrations (>500 mg/L).

Laboratory investigations into the potential anticaries efficacy of fluoride varnishes.

Science.gov (United States)

Lippert, Frank; Hara, Anderson Takeo; Martinez-Mier, Esperanza Angeles; Zero, Domenick T

2014-01-01

The purpose of this study was to investigate the potential anticaries efficacy of fluoride varnishes (FVs) by studying their ability to reharden and deliver fluoride to carious lesions and to release fluoride into saliva. Enamel carious lesions were created and allocated to 24 groups (11 FVs with two FV incubation times and two control groups) based on Knoop microhardness test values. FVs were applied to lesions, which were incubated in artificial saliva for two or six hours, with saliva being renewed hourly. FV was removed and lesions were remineralized in artificial saliva for 22 hours. Microhardness was measured and enamel fluoride uptake (EFU) was determined. Saliva samples (six-hour groups) were analyzed to determine fluoride release characteristics. Data were analyzed using analysis of variance. FVs differed considerably in their ability to reharden and deliver fluoride to carious lesions and in their fluoride release characteristics. Little consistency was found between investigated study variables for virtually all tested FVs. For example, a particular FV showed the highest EFU and fluoride release values but the lowest rehardening value. A longer FV contact time led to increased EFU for five of the 11 FVs. Some FVs delivered more fluoride to lesions in two hours than others did in six hours. Fluoride varnishes differ greatly in their in vitro anticaries efficacy.

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.

Field-portable-XRF reveals the ubiquity of antimony in plastic consumer products.

Science.gov (United States)

Turner, Andrew; Filella, Montserrat

2017-04-15

Very little systematic information exists on the occurrence and concentrations of antimony (Sb) in consumer products. In this study, a Niton XL3t field-portable-X-ray fluorescence (FP-XRF) spectrometer was deployed in situ and in the laboratory to provide quantitative information on Sb dissipated in plastic items and fixtures (including rubber, textile and foamed materials) from the domestic, school, vehicular and office settings. The metalloid was detected in 18% of over 800 measurements performed, with concentrations ranging from about 60 to 60,000μgg -1 . The highest concentrations were encountered in white, electronic casings and in association with similar concentrations of Br, consistent with the use of antimony oxides (e.g. Sb 2 O 3 ) as synergistic flame retardants. Concentrations above 1000μgg -1 , and with or without Br, were also encountered in paints, piping and hosing, adhesives, whiteboards, Christmas decorations, Lego blocks, document carriers, garden furniture, upholstered products and interior panels of private motor vehicles. Lower concentrations of Sb were encountered in a wide variety of items but its presence (without Br) in food tray packaging, single-use drinks bottles, straws and small toys were of greatest concern from a human health perspective. While the latter observations are consistent with the use of antimony compounds as catalysts in the production of polyethylene terephthalate, co-association of Sb and Br in many products not requiring flame retardancy suggests that electronic casings are widely recycled. Further research is required into the mobility of Sb when dissipated in new, recycled and aged polymeric materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Water fluoridation for the prevention of dental caries.

Science.gov (United States)

Iheozor-Ejiofor, Zipporah; Worthington, Helen V; Walsh, Tanya; O'Malley, Lucy; Clarkson, Jan E; Macey, Richard; Alam, Rahul; Tugwell, Peter; Welch, Vivian; Glenny, Anne-Marie

2015-06-18

Dental caries is a major public health problem in most industrialised countries, affecting 60% to 90% of school children. Community water fluoridation was initiated in the USA in 1945 and is currently practised in about 25 countries around the world; health authorities consider it to be a key strategy for preventing dental caries. Given the continued interest in this topic from health professionals, policy makers and the public, it is important to update and maintain a systematic review that reflects contemporary evidence. To evaluate the effects of water fluoridation (artificial or natural) on the prevention of dental caries.To evaluate the effects of water fluoridation (artificial or natural) on dental fluorosis. We searched the following electronic databases: The Cochrane Oral Health Group's Trials Register (to 19 February 2015); The Cochrane Central Register of Controlled Trials (CENTRAL; Issue 1, 2015); MEDLINE via OVID (1946 to 19 February 2015); EMBASE via OVID (1980 to 19 February 2015); Proquest (to 19 February 2015); Web of Science Conference Proceedings (1990 to 19 February 2015); ZETOC Conference Proceedings (1993 to 19 February 2015). We searched the US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization's WHO International Clinical Trials Registry Platform for ongoing trials. There were no restrictions on language of publication or publication status in the searches of the electronic databases. For caries data, we included only prospective studies with a concurrent control that compared at least two populations - one receiving fluoridated water and the other non-fluoridated water - with outcome(s) evaluated at at least two points in time. For the assessment of fluorosis, we included any type of study design, with concurrent control, that compared populations exposed to different water fluoride concentrations. We included populations of all ages that received fluoridated water (naturally or artificially

Nanoscaled hydrated antimony (V oxide as a new approach to first-line antileishmanial drugs

Directory of Open Access Journals (Sweden)

Franco AMR

2016-12-01

Full Text Available Antonia MR Franco,1 Iryna Grafova,2 Fabiane V Soares,1,3 Gennaro Gentile,4 Claudia DC Wyrepkowski,1,3 Marcos A Bolson,5 Ézio Sargentini Jr,5 Cosimo Carfagna,4 Markku Leskelä,2 Andriy Grafov2 1Laboratory of Leishmaniasis and Chagas Disease, National Institute of Amazonian Research (INPA, Manaus, Amazonas, Brazil; 2Department of Chemistry, University of Helsinki, Helsinki, Finland; 3Multi-Institutional Post-Graduate Program in Biotechnology, Federal University of Amazonas, Manaus, Amazonas, Brazil; 4Institute for Polymers, Composites, and Biomaterials, National Research Council, Pozzuoli, Naples Province, Italy; 5Laboratory of Environmental Chemistry, National Institute of Amazonian Research (INPA, Manaus, Amazonas, Brazil Background: Coordination compounds of pentavalent antimony have been, and remain, the first-line drugs in leishmaniasis treatment for >70 years. Molecular forms of Sb (V complexes are commercialized as sodium stibogluconate (Pentostam® and meglumine antimoniate (MA (Glucantime®. Ever-increasing drug resistance in the parasites limits the use of antimonials, due to the low drug concentrations being administered against high parasitic counts. Sb5+ toxicity provokes severe side effects during treatment. To enhance therapeutic potency and to increase Sb (V concentration within the target cells, we decided to try a new active substance form, a hydrosol of Sb2O5⋅nH2O nanoparticles (NPs, instead of molecular drugs. Methodology/principal findings: Sb2O5⋅nH2O NPs were synthesized by controlled SbCl5 hydrolysis in a great excess of water. Sb2O5⋅nH2O phase formation was confirmed by X-ray diffraction. The surface of Sb (V NPs was treated with ligands with a high affinity for target cell membrane receptors. The mean particle size determined by dynamic light scattering and transmission electron microscopy was ~35–45 nm. In vitro tests demonstrated a 2.5–3 times higher antiparasitic activity of Sb (V nanohybrid hydrosols

Water Fluoridation Reporting System (Public Water Systems)

Data.gov (United States)

U.S. Department of Health & Human Services — The Water Fluoridation Reporting System (WFRS) has been developed to provide tools to assist states in managing fluoridation programs. WFRS is designed to track all...

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.

Comparative evaluation of fluoride release and recharge of pre-reacted glass ionomer composite and nano-ionomeric glass ionomer with daily fluoride exposure: An in vitro study

Directory of Open Access Journals (Sweden)

Jayanthi Mungara

2013-01-01

Full Text Available Aim: This in vitro study was designed to investigate the effects of daily fluoride exposures on fluoride release and recharge by prereacted glass ionomer (PRG composite and nano-ionomeric glass ionomer. Materials and Methods: Seventy-two specimens (36 of each material were prepared and by placing the restorative materials into Teflon mold. Each specimen was subjected to one of three daily treatments (n = 12: (1 No fluoride treatment (control; (2 application of a fluoride dentifrice (1,000 ppm once daily; and (3 the same regimen as (2, plus immersion in a 0.05% sodium fluoride (NaF mouth rinse (225 ppm immediately following the dentifrice application. Specimens were suspended in a storage vial containing 10 ml demineralizing solution for 6 h and transferred to a new test tube containing 10 ml remineralizing solution for 18 h. Fluoride treatments of the specimens were completed every day prior to their immersion in the demineralizing solution. Media solutions were buffered with equal volumes of total ionic strength adjustment buffer (TISAB II; fluoride levels were measured using a digital ion analyzer and fluoride electrode throughout the 21 day duration of the experiment. Results: Nano-ionomeric glass ionomer showed a better amount of fluoride release than PRG composite irrespective of the fluoride treatment supplementation (P < 0.01. Additional fluoride supplementation improved fluoride release and recharge ability for both the materials when compared to their respective control groups. The fluoride recharge for both materials did not show any sustained pattern of release. Conclusion: Nano-ionomeric glass ionomer demonstrated a greater ability to release and recharge compared with that of PRG composite.

Fluoride removal from water by nano filtration

International Nuclear Information System (INIS)

Bejaoui, Imen; Mnif, Amine; Hamrouni, Bechir

2009-01-01

As any oligo element, fluoride is necessary and beneficial for human health to low concentrations, but an excess amount of fluoride ions in drinking water has been known to cause undesirable effects, especially tooth and bones fluoro sis. The maximum acceptable concentration of fluoride in drinking water was fixed by the World Health Organization according to the climate in the range of 1 mg.L -1 to 1,2 mg.L -1 . Many methods have been used to remove fluoride from water such as precipitation, adsorption, electrocoagulation and membrane processes. Technologies using membrane processes are being used in many applications, particularly for brackish water desalination. Nano filtration seems to be the best process for a good selective defluorination of fluorinated waters. The main objective of this work was to investigate the retention of fluoride anions by nano filtration. The first part of this study deals with the characterisation of the NF HL2514TF membrane. The influence of various experimental parameters such as initial fluoride content, feed pressure, permeate flux, ionic strength, type of cation associated to fluoride and pH were studied in the second part. Results show that the retention order for the salts tested was TR(Na 2 SO 4 ) > TR(CaCl 2 ) > TR(NaCl), showing a retention sequence inversely proportional to the salt diffusion coefficients in water. It was also shown that charge effects could not be neglected, and a titration experiments confirmed that the NF membrane carry a surplus of negatively charged groups. Fluoride retention exceeds 60 pour cent, and increases with increasing concentration, where the rejection mechanism is related to the dielectric effects. Speigler-Kedem model was applied to experimental results in the aim to determine phenomenological parametersσand P s respectively, the reflexion coefficient of the membrane and the solute permeability of ions. The convective and diffusive parts of the mass transfer were quantified with

Studies on the comparative effect of sodium fluoride on collagen ...

African Journals Online (AJOL)

Fluoride is an essential element for the normal development and growth of human beings. The main source of fluoride for humans is the intake of groundwater. At high levels, fluoride causes dental and skeletal fluorosis. In this study, control and sodium fluoride (NaF) treated groups of rats had significant (p < 0.05) higher ...

Study on Stereochemical Activity of Lone Pair Electrons in Sulfur and Halogen Coordinated Antimony(III) Complexes by 121Sb Moessbauer Spectroscopy

International Nuclear Information System (INIS)

Ohyama, Ryuhichi; Takahashi, Masashi; Takeda, Masuo

2005-01-01

We have measured 121 Sb Moessbauer spectra at 20 K for 52 compounds of antimony(III). An Sb(III) atom with the electron configuration [Kr] 4d 10 5s 2 has a lone pair electrons. The stereochemical property of the lone pair has been found to depend very much on the kinds of atoms surrounding the antimony atom and the configurations of the coordinating atoms.

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.

Removal of fluoride from water using aluminium containing compounds

Institute of Scientific and Technical Information of China (English)

M. Karthikeyan; K. P. Elango

2009-01-01

Batch adsorption studies were undertaken to assess the suitability of aluminium titanate (AT) and bismuth aluminate (BA) to remove fluoride ions from water.The effect of pH,dose of adsorbent,contact time,initial concentration,co-ions and temperature on fluoride removal efficiency were studied.The amounts of fluoride ions adsorbed,at 30℃ from 4 mg/L of fluoride ion solution,by AT and BA are 0.85 and 1.55 mg/g,respectively.The experimental data fitted well to the Freundlich and Langmuir isotherms.Thermodynamic parameters such as △H~0,△S~0 and △G~0 indicated that the removal of fluoride ions by AT is exothermic and non-spontaneous while that by BA is endothermic and spontaneous.Furrier transform infrared (FT-IR) analysis and X-ray diffraction (XRD) patterns of the adsorbent before and after adsorption indicated that fluoride ions are chemisorbed by these adsorbents.

Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

International Nuclear Information System (INIS)

Meublat, L.

1989-10-01

The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), CIO 2 + RuF 6 - , a new compound well identified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

International Nuclear Information System (INIS)

Meublat, L.

1989-01-01

The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), ClO 2 + RuF 6 - , a new compound well idendified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

Purification of Drinking Water from Fluorides by Reverse Osmosis

Directory of Open Access Journals (Sweden)

Aleksander A.

2018-03-01

Full Text Available Introduction: An important task in the sphere of sanitary and epidemiological welfare of the population of the Russian Federation is provision of drinking water. Tap water must not contain pathogenic bacteria and dangerous chemicals. Purification systems regulate the concentration of fluoride ions in drinking water. The aim of this paper is to study the possibility of purifying tap water from fluoride ions by reverse osmosis. Materials and Methods: We used the Alfa Laval PilotUnit 2.5 "RO/NF with a set of spiral-type membrane elements RO99-2517/48 to remove fluoride ions. We measured the concentration of fluoride ions by the potentiometric method using the Hanna HI 2211 (pH/mV/T. Fluoride-selective electrode ELIS 131 F was used as an indicator electrode and the standard chloride-silver electrode EVL-1M3 was used as a reference electrode. Both the calibration and buffer solutions were prepared from chemically pure reagents and A. R. purity for analysis reagents according to GOST 4386-89. Results: A single passage of water through the reverse osmosis membrane reduced the concentration of fluoride ions from 2.29 ± 0.02 to 0.240 ± 0.015 mg/l. Double passage of water reduced the concentration by a factor of two. As the concentration of fluoride ions increased in the retentate, the concentration in the filtrate slightly increased too. Purification of water reduced the concentration of fluoride ions from 20 mg/l, to 0.5 mg/l. Discussion and Conclusions: Thus, using the Alfa Laval PilotUnit 2.5" RO/NF with a set of spiral-type membrane elements RO99-2517/48 filters tap water of ions of fluoride to the maximum allowable concentration. This study opens the perspective of using reverse osmosis to purify tap water with high concentration of fluoride ions.

Influence of nanosized inclusions on the room temperature thermoelectrical properties of a p-type bismuth–tellurium–antimony alloy

International Nuclear Information System (INIS)

Bernard-Granger, Guillaume; Addad, Ahmed; Navone, Christelle; Soulier, Mathieu; Simon, Julia; Szkutnik, Pierre-David

2012-01-01

Transmission electron microscopy observations and thermoelectrical property measurements (electrical conductivity, Seebeck coefficient and thermal conductivity) at room temperature have been completed on two fully dense polycrystalline p-type bismuth–tellurium–antimony alloy samples. It is shown that the presence of antimony oxide-based nanosized inclusions (controlled as to volume fraction and size distribution), homogeneously dispersed in the surrounding matrix leads to a dimensionless figure of merit (ZT) of ∼1.3 at room temperature. For comparison, when such inclusions are missing the ZT value is only 0.6.

Field-based scanning tunneling microscope manipulation of antimony dimers on Si(001)

NARCIS (Netherlands)

Rogge, S.; Timmerman, R.H.; Scholte, P.M.L.O.; Geerligs, L.J.; Salemink, H.W.M.

2001-01-01

The manipulation of antimony dimers, Sb2, on the silicon (001) surface by means of a scanning tunneling microscope (STM) has been experimentally investigated. Directed hopping of the Sb2 dimers due the STM tip can dominate over the thermal motion at temperatures between 300 and 500 K. Statistics on

Theoretical Analysis of Rydberg and Autoionizing State Spectra of Antimony

Institute of Scientific and Technical Information of China (English)

Shuang-Fei Lv; Ruohong Li; Feng-Dong Jia; Xiao-Kang Li; Jens Lassen; Zhi-Ping Zhong

2017-01-01

We calculate the Rydberg and autoionization Rydberg spectra of antimony (Sb) from first principles by relativistic multichannel theory within the framework of multichannel quantum defect theory.Our calculation can be used to classify and assign the atomic states described in recently reported three Rydberg series and four autoionizing states.The perturbation effects on line intensity,variation and line profile are discussed.Assignments of the perturber states and autoionizing states are presented.