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Sample records for iodometry

  1. Redox-iodometry: a new potentiometric method.

    PubMed

    Gottardi, Waldemar; Pfleiderer, Jörg

    2005-07-01

    A new iodometric method for quantifying aqueous solutions of iodide-oxidizing and iodine-reducing substances, as well as plain iodine/iodide solutions, is presented. It is based on the redox potential of said solutions after reaction with iodide (or iodine) of known initial concentration. Calibration of the system and calculations of unknown concentrations was performed on the basis of developed algorithms and simple GWBASIC-programs. The method is distinguished by a short analysis time (2-3 min) and a simple instrumentation consisting of pH/mV meter, platinum and reference electrodes. In general the feasible concentration range encompasses 0.1 to 10(-6) mol/L, although it goes down to 10(-8) mol/L (0.001 mg Cl2/L) for oxidants like active chlorine compounds. The calculated imprecision and inaccuracy of the method were found to be 0.4-0.9% and 0.3-0.8%, respectively, resulting in a total error of 0.5-1.2%. Based on the experiments, average imprecisions of 1.0-1.5% at c(Ox)>10(-5) M, 1.5-3% at 10(-5) to 10(-7) M, and 4-7% at <10(-7) M were found. Redox-iodometry is a simple, precise, and time-saving substitute for the more laborious and expensive iodometric titration method, which, like other well-established colorimetric procedures, is clearly outbalanced at low concentrations; this underlines the practical importance of redox-iodometry.

  2. Determination of Free Lime in Clinker and Cement by Iodometry. An Undergraduate Experiment in Redox Titrimetry

    NASA Astrophysics Data System (ADS)

    Lau, Oi-Wah; Luk, Shiu-Fai; Cheng, Nina L. N.; Woo, Hoi-Yin

    2001-12-01

    An interesting application of the determination of acid by iodometry is proposed for the determination of free lime in clinker and cement. Free lime in the sample is first extracted with nonaqueous ethylene glycol at 70 °C for 15 minutes. The filtered suspension is reacted with a known excess of hydrochloric acid. The excess acid is determined by iodometry. The proposed method is better than the classical British Standard method in terms of speed, sensitivity, and precision. It is an excellent addition to the undergraduate analytical experiments currently available, where within a single experiment students can make use of analytical techniques such as nonaqueous extraction, filtration, and iodometry as well as some statistical methods in analysis. It also gives students an opportunity to become familiar with the cement industry. The method is suitable to be adopted for the analysis of free lime in clinker and cement in a cement plant or a commercial laboratory.

  3. Determination of the reduced sulfur species in the anoxic zone of the Black Sea: A comparison of the spectrophotometry and iodometry techniques

    NASA Astrophysics Data System (ADS)

    Dubinin, A. V.; Demidova, T. P.; Kremenetskii, V. V.; Kokryatskaya, N. M.; Rimskaya-Korsakova, M. N.; Yakushev, E. V.

    2012-04-01

    The report presents the results of the studies of the reduced sulfur species in the water of the anoxic zone of the Black Sea. The content of hydrogen sulfide was determined by means of spectrophotometry using dilution with oxygen-free distilled water. The detection limit of the H2S amounted to 0.3 μM with the method's precision below 3%. The accuracy of the spectrophotometric determination was verified by iodometry after the fixation of the hydrogen sulfide in zinc acetate under the distillation with argon from the acidified seawater sample.

  4. Determination of oxygen contents of Bi1.9-xPbxSb0.1Sr2Ca2Cu3Oy by iodometry and its relevance to superconducting transition

    NASA Astrophysics Data System (ADS)

    Alauddin, M.; Vigdorchik, L. V.; Akbar, S. A.; Chaudhury, Z. A.; Ehmann, W. D.; Ni, B.-F.

    1992-02-01

    The effect of metal doping on the transition temperature (Tc) of Bi1.9-xPbxSb0.1Sr2Ca2Cu3Oy (0.05≤×≤0.40) was investigated. Doping with 10 atom% Pb produced a sample with maximum Tc in the series. The oxidation state of Cu and oxygen stoichiometry in these cuprates were determined by iodometry and fast neutron activation analysis (FNAA). Excellent agreement in oxygen data derived from iodometry and FNAA were observed. An apparent relationship between the average oxidation state of Cu and Tc values of these materials were observed.

  5. Polyvinyl alcohol as a useful indicator on iodometry: volumetric and spectrophotometric studies on iodine-PVA and iodine-starch complexes.

    PubMed

    Yoshinaga, T; Shirakata, T; Dohtsu, H; Hiratsuka, H; Hasegawa, M; Kobayashi, M; Hoshi, T

    2001-02-01

    Iodometry is one of the easiest, most rapid and accurate methods for the determination of a relatively small amount of oxidizing agent, such as residual chlorine. Starch has long been used as a useful color indicator in iodometry. However, we found that PVA (polyvinyl alcohol with partially saponificated; e.g., saponification degree of 88%) is a more useful color indicator than starch. For example, at 20 degrees C, the PVA indicator gave similar profiles of iodine concentration vs. titration efficiencies (percent recoveries) to those of starch at 0 degrees C. At 0 degrees C, the PVA indicator detected 1.1 mg I2/L (11 microg I2: with 10 mL sample volume) with a high percentage of recovery (=95%). Furthermore, at 20 degrees C an iodine concentration of 0.36 mg/L (which corresponds to a residual chlorine concentration of 0.1 mg Cl2/L) could be detected using PVA color indicator assuming an appropriate correction.

  6. Dependence of superconducting properties on the Cu-valence determined by iodometry in HgBa 2CuO 4+δ

    NASA Astrophysics Data System (ADS)

    Fukuoka, A.; Tokiwa-Yamamoto, A.; Itoh, M.; Usami, R.; Adachi, S.; Yamauchi, H.; Tanabe, K.

    1996-02-01

    We have synthesized nearly single-phase HgBa 2CuO 4+δ samples with various oxygen contents, and systematically investigated the relationship between the lattice parameters, the superconductivity transition temperature ( Tc) and the oxygen content determined by iodometry. Furthermore, the nominal copper valence values were calculated from the oxygen content data by assuming constant valence values of +2.00 and -2.00 for mercury and oxygen, respectively. Both the a and c lattice parameters were found to decrease monotonically with the Cu valence over a wide range of +2.05-2.28. The obtained Tc versus Cu valence curve exhibits a “bell shaped” correlation with the maximum in Tc at the Cu valence of ∼ +2.18.

  7. Application of direct thermometric analysis in iodometry.

    PubMed

    Marik-Korda, P; Erdey, L

    1970-12-01

    Elementary chlorine was determined by a thermometric method using potassium iodide as reagent. The temperature rise corresponding to the heat of reaction was proportional to the chlorine content. Iodine formed in the reaction was also determined with sodium thiosulphate. The heat of the chlorine-iodide reaction is about five times that of the iodine-thiosulphate reaction. Direct determination with potassium iodide is simpler and more rapid than the indirect one.

  8. [Quantitative determination of penicillins by iodometry using potassium hydrogen peroxymonosulfate].

    PubMed

    Blazhevskiĭ, N E; Karpova, S P; Kabachyĭ, V I

    2013-01-01

    The kinetics and stoichiometry of S-oxidation of semisynthetic penicillins (amoxicillin trihydrate, ampicillin trihydrate, sodium salt of oxacillin and ticarcillin disodium salt) by potassium hydrogen peroxymonosulfate in aqueous solutions at pH 3-6 was studied by iodometric titration: 1 mol of KNSO5 per 1 mol of penicillin, the quantitative interaction is achieved in 1 min (time of observation). A unified method was developed and the possibility of quantification of penicillins by the iodometric method using potassium hydrogen peroxymonosulfate as an analytical reagent was shown.

  9. Determination of lipid hydroperoxides in serum iodometry and high performance liquid chromatography compared.

    PubMed

    Wieland, E; Schettler, V; Diedrich, F; Schuff-Werner, P; Oellerich, M

    1992-06-01

    It is postulated that lipid peroxidation plays a role in the pathogenesis of a variety of diseases. Efforts have therefore been made to develop reliable and practicable procedures for quantifying lipid peroxidation products such as lipid hydroperoxides in biological specimens. An iodometric cholesterol colour reagent (Merck, Darmstadt, Germany) can be used to measure lipid hydroperoxides in isolated low density lipoproteins without lipid extraction. This method has been validated with respect to its analytical performance and suitability for serum samples by comparing it with a high performance liquid chromatography technique. The method was found to have acceptable performance characteristics with aqueous fatty acid hydroperoxide solutions (linoleic acid) and isolated low density lipoproteins, but it cannot be applied to native serum samples without extraction of lipids.

  10. Polyvinyl alcohol as a useful indicator on iodometry. (II): Temperature dependence of iodine recovery and the correction method of iodine concentration in the lower detection limit region.

    PubMed

    Yoshinaga, Tetsutaro; Tsuchida, Makoto; Toyose, Yasushi; Hiratsuka, Hiroshi; Yamaye, Makoto

    2004-03-01

    In an iodometric titration method for iodine (or chlorine) analysis, the percent recovery of iodine (or chlorine) decreases in the low concentration region and at the relatively higher temperature range. We have shown that the percent recovery vs. concentration curve can be expressed by a simple empirical formula. The empirical formula contains parameters that depend on temperature and those parameters were obtained as a function of temperature. The empirical formula can be used as a correction function for experimental iodine (or chlorine) concentrations. By applying the correction function with the parameters to the experimentally obtained concentrations, we can estimate the reliable concentration in the low concentration region. Estimated concentrations were within 10% (as RSD) of the exact values after the correction in the range of 0.4 mg I2 L(-1) ([triple bond] ca. 0.1 mg as Cl2 L9-1)) - 4.4 mg I2 L(-1) ([triple bond] ca. 1.2 mg as Cl2 L(-1)) in the temperature range of 0 to 30 degrees C.

  11. The study of a new method to determine copper ion by square-wave voltammetry-extraction iodometry at the liquid/liquid interfaces.

    PubMed

    Shi, Changyan; Xie, Shaoai; Jia, Jinping

    2008-01-01

    A new method of indirect determination of Cu(2+) was developed based on square-wave voltammetry by the oxidation of iodide in organic solvent at the liquid/liquid (L/L) interface. The limit of detection for the determination of Cu(2+) in this method was found to be 5 x 10(-4) mol/L, and the concentration ranged up to 1 x 10(-2) mol/L gave a linear limiting current versus concentration response. For the same simulated wastewater, this method showed high accuracy compared with the result tested by sodium diethyldithiocarbamate extraction spectrophotometry. This approach could be applied to the indirect determination of the oxidative heavy metals in the industrial wastewater.

  12. The Study of a New Method to Determine Copper Ion by Square-Wave Voltammetry-Extraction Iodometry at the Liquid/Liquid Interfaces

    PubMed Central

    Shi, Changyan; Xie, Shaoai; Jia, Jinping

    2008-01-01

    A new method of indirect determination of Cu2+ was developed based on square-wave voltammetry by the oxidation of iodide in organic solvent at the liquid/liquid (L/L) interface. The limit of detection for the determination of Cu2+ in this method was found to be 5 × 10−4 mol/L, and the concentration ranged up to 1 × 10−2 mol/L gave a linear limiting current versus concentration response. For the same simulated wastewater, this method showed high accuracy compared with the result tested by sodium diethyldithiocarbamate extraction spectrophotometry. This approach could be applied to the indirect determination of the oxidative heavy metals in the industrial wastewater. PMID:19096710

  13. Preparation and Properties of Non-Crystalline Glasses in the System Se-I

    DTIC Science & Technology

    2001-06-01

    34Transylvania", 2200-Brasov, Romania Vitreous Sexl-., samples (x=0.1; 0.15; 0.20) have been prepared and studied by thermal analysis, iodometry , X-ray...thermogravimetric curves reveal important loss of material (iodine) of the same order of magnitude as for the losses observed by iodometry measurements. 3.3

  14. PH Dependent Interactions between Aqueous Iodide Ion and Selected Oxidizers.

    DTIC Science & Technology

    1985-12-06

    COSATI CODES I&. SUBJECT IERMS (Continue an evven d mocesaey and idoetfy by 510&k number) C’ ELD GROUP SUB-ROUP >Oxidize Iodometry Titration Oxidation... iodometry : hypochlorite interacts instantly with iodide ion. However, a kinetically rapid decon reaction may not be best for all possible situations. An

  15. A Simple Fluorometry of Hydroperoxides in Oils and Foods.

    PubMed

    Akasaka, K; Sasaki, I; Ohrui, H; Meguro, H

    1992-01-01

    A fluorometry of hydroperoxides in oil and food samples was developed using diphenyl-1-pyrenylphosphine (DPPP) with a sample size of less than 20 mg by a batch method. The sensitivity was more than 10,000 times that of the conventional iodometry. A good accordance was obtained between peroxide values (POV) measured this way and by iodometry (r = 0.9995, n = 41, POV = 0.04-240).

  16. Modern Chemical Technology, Volume 5.

    ERIC Educational Resources Information Center

    Pecsok, Robert L., Ed.; Chapman, Kenneth, Ed.

    This volume contains chapters 26-31 for the American Chemical Society (ACS) "Modern Chemical Technology" (ChemTeC) instructional material intended to prepare chemical technologists. Chapter 26 reviews oxidation and reduction, including applications in titrations with potassium permanganate and iodometry. Coordination compounds are…

  17. [Spectrophotometric determination of phenol and sodium tosylchloramide].

    PubMed

    Kovacević, G; Bodiroga, M; Jasminka, O

    1991-01-01

    A possible quantitative analysis of oil injections of phenol and tosylchloramide sodium solution using the spectrophotometric method in the UV field has been examined. The results have been compared with results of official methods, bromometry and iodometry. The proposed spectrophotometric method is suitable due to its speed and simplicity in work giving precise and reproducible results.

  18. Selective assay of benzoyl peroxide in lotions and creams.

    PubMed

    Daly, R E; Lomner, J J; Chafetz, L

    1975-12-01

    A selective titrimetric method for the determination of benzoyl peroxide in lotions and creams was developed. It is based on the work of Horner and Jürgens, in which diacylperoxides, dialkylperoxides, peracids, and alkylhydroperoxides can be determined selectively by iodometry and acidimetry. The proposed assay is stability indicating with respect to peracids. Good recovery data were obtained.

  19. Determination of organically bound iodine by reductive mineralization with aluminium powder. Analytical methods of pharmacopoeias with DBH in respect to environmental and economical concern. Part 16.

    PubMed

    Hilp, M

    2002-07-01

    PH. EUR. 2002, JAP 1996 and USP 2000 mineralize organically bound iodine in x-ray contrast media by boiling under reflux with zinc powder in alkaline solution. The reductive mineralization can be performed at room temperature without filtration, when aluminium powder is used. Resulting iodide is titrated by argentometry and potentiometric indication according to the pharmacopoeia or after oxidation with 1,3-dibromo-5,5-dimethylhydantoin by iodometry.

  20. Titrimetric determination of hydrogen peroxide in alkaline solution.

    PubMed

    McCurdy, W H; Bell, H F

    1966-07-01

    Direct titration of hydrogen peroxide in alkaline bromide media has been accomplished with sodium hypochlorite. The relative standard deviation is 0.2%. A photometric end-point is recommended for the determination of 0.10-1.0 mequiv of peroxide. Larger samples are evaluated by use of Bordeaux Red as visual indicator. The hypochlorite procedure compares favourably with iodometry and permanganate in the analysis of commercial peroxides.

  1. Relationship between hydroperoxide concentration and average molar mass in thermo-oxidized polyethylene

    NASA Astrophysics Data System (ADS)

    Da Cruz, Manuela; Van Schoors, Laetitia; Colin, Xavier; Benzarti, Karim

    2014-05-01

    The aim of this research project is to investigate the oxidation mechanism of high density polyethylene (HDPE) used in outdoor applications, in order to establish in a near future, a non-empirical kinetic model for lifetime prediction. The present paper focuses on the changes in the hydroperoxide (POOH) concentration induced by thermo-oxidative ageing, and on their relationship with the evolution of the weight average molar mass (Mw) due both to chain scission and crosslinking processes. Thin HDPE films were aged at 110 and 140°C in air under atmospheric pressure. In a first part, changes in the POOH concentration versus ageing time were assessed by three different analytical methods previously reported in the literature: modulated differential scattering calorimetry (MDSC), Fourier transform Infra-Red spectrometry after chemical derivatization treatment with gaseous sulfur dioxide (SO2-FTIR), and iodometry. A comparison of experimental results revealed that these three methods provide very similar quantitative data on POOH accumulation, whereas iodometry tends to strongly underestimate the subsequent stage of POOH decomposition. It was thus suspected that iodometry does not only titrate POOH, but also other chemical species (presumably double bonds) formed when POOH decompose. Therefore, only MDSC and SO2-FTIR were considered as relevant methods for POOH titration. In a second part, changes in Mw versus ageing time were monitored by size exclusion chromatography (SEC). A sharp drop of Mw was first observed at the beginning of exposure, which was assigned to an intensive chain scission process. Then, in a second stage, a stabilization or even a substantial re-increase in Mw was observed, suggesting a competition between chain scission and crosslinking processes. As this second stage starts at the same time as POOH decomposition, it was concluded that there is a strong correlation between both phenomena, occurring respectively at the macromolecular and molecular

  2. [The Ascorbic Acid Reference Standard (Control 931) of the National Institute of Health Sciences].

    PubMed

    Kitajima, A; Yoshii, K; Komatsu, H; Ishimitsu, S; Okada, S

    1994-01-01

    Raw ascorbic acid material was tested for preparation of the "Ascorbic Acid Reference Standard (Control 931)". Analytical data obtained were as follows: infrared spectrum, the same as that of the JP Ascorbic Acid Reference Standard; optical rotation -alpha-20D, + 21.4 degrees; melting point, 190.3 degrees C (decomposition); loss on drying, 0.02%; assay result, 100.1% by iodometry. Based on the above findings, the raw material was authorized as the JP Ascorbic Acid Reference Standard (Control 931).

  3. Morphology and etching studies on YBCO and CuO single crystals

    NASA Astrophysics Data System (ADS)

    Prabhakaran, D.; Subramanian, C.; Balakumar, S.; Ramasamy, P.

    1999-06-01

    Single crystals of YBCO (Y123) and CuO have been grown from a BaO-CuO (28:72) flux using a low axial gradient furnace (∼1°C/cm). Growth morphology of the grown crystals was studied using an optical microscope, scanning electron microscopy and atomic force microscopy. Cell parameter values and chemical composition of the grown crystals were determined from the X-ray diffraction data and inductively coupled plasma analysis, respectively. Etching studies were done for both the crystals using different etchants. Oxygen stoichiometry of the YBCO crystal was determined by iodometry titration analysis.

  4. Neutron Diffraction Study of Nonstoichiometry in Ba1.5La1.5Cu3Oy

    NASA Astrophysics Data System (ADS)

    Izumi, Fujio; Takayama-Muromachi, Eiji; Kobayashi, Michiko; Uchida, Yoshishige; Asano, Hajime; Ishigaki, Tōru; Watanabe, Noboru

    1988-05-01

    The structure parameters of annealed and quenched samples of Ba1.5La1.5Cu3Oy were refined by the Rietveld analysis of TOF neutron powder diffraction data. Partial occupation of an oxygen site at (0, 1/2, 0) causes nonstoichiometry in the oxide. The y values calculated from the occupation factors of oxygen at this site are 7.20 (annealed) and 6.76 (quenched), which are in fair agreement with those determined by iodometry: 7.15 (annealed) and 6.74 (quenched).

  5. Superconductivity of Bi 2-xPb xSr 2-xLn xCuO y(Ln=La,Nd) and valence analysis of Bi and Cu

    NASA Astrophysics Data System (ADS)

    Kikuchi, M.; Nameki, H.; Syono, Y.; Suzuki, R.; Nagoshi, M.; Awaji, S.; Kobayashi, N.

    1991-12-01

    Bi 2-ZPb zSr 2-x(La/Nd) xCuO y (z=0 and 0.4, x=0.2-1.0) was synthesized in air and nitrogen atmosphere. Valence analyses by dichromate titration and iodometry showed Bi valence larger than 3.0 and Cu valence close to 2+ over the wide range of x, being difficult to explain superconductivity. The Tc depends on substituent lanthanoid, La or Nd. The maximum Tc was achieved at x=0.4-0.5 in all these series.

  6. In situ quantitative and kinetic study by Fourier transform raman spectroscopy of reaction between nitriles and hydroperoxides

    NASA Astrophysics Data System (ADS)

    Vacque, V.; Dupuy, N.; Sombret, B.; Huvenne, J. P.; Legrand, P.

    1997-06-01

    The reaction of nitrile with alkaline hydrogen peroxide has been studied kinetically by means of iodometry several times. We proposed to set up an in situ analytical method to follow the consumption of nitrile. We applied FT-Raman spectroscopy coupled with a partial least-squares quantitative method to the study the reactions of hydrogen peroxide or tert-butyl hydroperoxide on benzonitrile and acetonitrile. The results obtained led us to conclusions on the reactivity of the hydroperoxides and on the rate of consumption of nitrile. Our study made also clear that FT-Raman spectroscopy was a convenient tool for controlling industrial processes.

  7. The oxidation of linoleic acid in the Udenfriend's system.

    PubMed

    Wakizaka, A; Imai, Y

    1974-11-01

    The autocatalytic oxidation of linoleate was observed in the incubation mixture containing ferrous ion and ascorbic acid as the catalysts (Undenfriend's system). The rate of oxidation of linoleate was estimated wither by the TBA method, iodometry or by the measurement of the absorbance at 235 nm. Reaction products were analyzed by TLC, GLC and UV-, IR-, NMR- and mass spectrometries. The main oxidized products were assumed to have one oxygen atom at the position of carbon 9 or 13 of linoleate or two oxygen atoms at the both positions of the original acid. The conjugated double bond was formed at carbon 10 and 12 of the carbon chain of linoleate.

  8. Determination of 1 x 10/sup -2/-1 x 10/sup 2/ g/dm/sup 3/ hydrazine in aqueous solutions with EPV-1 and EO-01 electrodes

    SciTech Connect

    Dracheva, L.V.

    1987-09-01

    The corrosion of copper alloy structures in thermal power plants is inhibited by treating aggressive media with highly reductive hydrazine hydrate. The hydrazine combines chemically with oxygen in the coolant used for steam condensation. The present iodometric method for monitoring and controlling high hydrazine levels in the coolant is lengthy, painstaking, and difficult to automate. This paper describes a potentiometric method for this determination and tests the electrochemical and redox behavior of two electrode materials--glass and platinum--in several electrolytes for this purpose. The potentiometric method is also compared to that of iodometry and found to be much more efficient, simple, and automatable.

  9. Superconducting properties and their relation with the hole concentration of La 1+ xBa 2- xCu 3O 7- δ system

    NASA Astrophysics Data System (ADS)

    Akinaga, H.; Takita, K.; Asano, H.; Masuda, K.

    1989-12-01

    The relation between superconducting transition temperature Tc and the hole concentration was investigated in single-phase samples of the La 1+ xBa 2- xCu 3O 7- δ solid solution system, where the hole concentration was changed by La-substitution for Ba ion. Hole concentration was determined by two different methods: Hall effect measurement and iodometry. T c decreased with decreased of pH(= {1}/{R He }). The hole concentration 3 p determined by the iodometry, where p is the average charge of [ shows no correlation with Tc. The hole concentration (2 ps in Cu-O sheets between La and Ba sites calculated based on Tokura's assumption gives a similar value to p H. This Tc-2 ps relation is almost the same to that of Ln 1+ xBa 2- xCu 3O 7- δ (Ln = Nd, Sm and Eu) reported previously. In spite of that the x-dependence of p in the present system is rather different from those of Nd-, Sm-and Eu-systems.

  10. Changes in modulation period of Bi 2Sr 2 (Ca 1- xNd x) Cu 2O a + δ and their relations to oxygen content

    NASA Astrophysics Data System (ADS)

    Onozuka, Takashi; Tokiwa, Ayako; Syono, Yasuhiko; Koike, Yoji; Saito, Yoshitami

    1991-12-01

    Structural changes of long-period modulated structure (LPMS) of the Bi 2Sr 2(Ca 1- xNd x) Cu 2O a + δ ceramics with x are investigated by means of electron diffraction. Increasing x, the modulation mode of the mixing of domains of two modulation periods with b=4.5b o and b=5b o changes to that with b=4.5b o and b=4b o through the modulation mode with only b=4.5b o at x=0.4-0.5. The wavenumber of the superlattice reflection shows a stepwise increase rather than a linear increase with x. Excess oxygen in a LPMS model with the site of excess oxygen is shown to be consistent with excess oxygen analyzed chemically by iodometry and its change with x.

  11. Simultaneous flow-injection measurement of hydroxide, chloride, hypochlorite and chlorate in Chlor-alkali cell effluents.

    PubMed

    Tian, K; Dasgupta, P K

    2000-07-31

    A flow injection method is reported for the simultaneous determination of hydroxide, chloride, hypochlorite, and chlorate ions that exist in Chlor-alkali cell effluents in concentrations ranging from sub-millimolar to several molar. The hydroxide concentration is determined by the heat of neutralization of the injected sample into an acidic carrier stream and the chloride concentration is calculated from the measured conductance data. For the measurement of hypochlorite and chlorate, colorimetric iodometry is used. Iodide is oxidized to iodine by OCl(-) and ClO(3)(-) in acid solutions. While room temperature is sufficient for the reaction between OCl(-) and I(-), the reaction between ClO(3)(-) and I(-) requires an elevated temperature. The different reaction requirements are utilized to differentiate between NaOCl and NaClO(3), respectively.

  12. Physicochemical properties and inhibition effect on iron deficiency anemia of a novel polysaccharide-iron complex (LPPC).

    PubMed

    Zhang, Zhong-Shan; Wang, Xiao-Mei; Han, Zhi-Ping; Yin, Li; Zhao, Ming-Xing; Yu, Shu-Chi

    2012-01-01

    Porphyran (P) was extracted from red algae Porphyra by boiling water. A novel polysaccharide-iron complex (LPPC) was prepared under the alkaline condition by adding a ferric chloride solution to the low molecular weight porphyran (LP) solution. Physicochemical properties and inhibition effect on iron deficiency anemia of this complex were studied. The content of iron(III) in the complex is 21.57% determined with iodometry. The results indicate that LPPC was product required. The complex can increase red blood cell count (RBC), hemoglobin (Hb), Serum iron (SI), spleen index, spleen mass and mass of mice with iron deficiency anemia (IDA). Although the structure and deeper mechanisms on hemolytic anemia of LPPC should be further studied, LPPC is hoped to be developed as a late-model iron supplement which has a synergism on anemia.

  13. Determination of sulphide by anion-exchange with lead iodate.

    PubMed

    Verma, K K; Gupta, D; Sanghi, S K; Jain, A

    1988-11-01

    A quick anion-exchange reaction, suitable for the determination of sulphide, has been found to occur on stirring a suspension of lead iodate (solubility product, K(s0) = 1.2 x 10(-13)) with sulphide solution at pH 5-8. After removal of the precipitates of lead iodate and lead sulphide (K(s0) = 3.4 x 10(-28)), the iodate released can be determined by its reaction with acidified iodide to give tri-iodide which is either titrated with thiosulphate or measured spectrophotometrically as its blue complex with starch. Chloride, bromide, iodide, fluoride, oxalate, sulphate, thiocyanate and phosphate do not interfere. Thiosulphate, sulphite, nitrite and thiols do not give an anion-exchange reaction but do interfere in the redox reaction of iodate with acidified iodide. However, this is avoided if they are first oxidized with bromine (the liberated iodate remains unaffected before iodometry.

  14. Glucose: Detection and analysis.

    PubMed

    Galant, A L; Kaufman, R C; Wilson, J D

    2015-12-01

    Glucose is an aldosic monosaccharide that is centrally entrenched in the processes of photosynthesis and respiration, serving as an energy reserve and metabolic fuel in most organisms. As both a monomer and as part of more complex structures such as polysaccharides and glucosides, glucose also plays a major role in modern food products, particularly where flavor and or structure are concerned. Over the years, many diverse methods for detecting and quantifying glucose have been developed; this review presents an overview of the most widely employed and historically significant, including copper iodometry, HPLC, GC, CZE, and enzyme based systems such as glucose meters. The relative strengths and limitations of each method are evaluated, and examples of their recent application in the realm of food chemistry are discussed.

  15. Some features of the oxidative conversion of Mo(CO)/sub 6/ in a medium of hydroperoxide or tert-butyl hydroperoxide and an aromatic hydrocarbon

    SciTech Connect

    Fomin, V.M.; Lunin, A.V.; Aleksandrov, Yu.A.

    1988-03-10

    Occurrence of the reaction under study was followed from the decrease in hydroperoxide or of Mo(CO)/sub 6/. The Mo(CO)/sub 6/ content of the reaction was found by determining either the concentration of this compound directly or by determining the concentration of the gaseous products from its transformations (CO + CO/sub 2/). Hydroperoxides (I) and (II) were determined iodometrically. Metal-containing products of the oxidation of Mo(CO)/sub 6/, molybdenum oxides and peroxides, were analyzed by IR and ESR spectroscopy, elemental analysis, and iodometry. Analysis of transformation products of the hydroperoxides (phenol, acetone, dimethylphenylcarbinol, acetophenone, tert-butyl alcohol, water, and oxygen) was performed using gas chromatography. Results are presented.

  16. Hydroperoxide formation in model collagens and collagen type I.

    PubMed

    Madison, S A; McCallum, J E B; Rojas Wahl, R U

    2002-02-01

    Protein hydroperoxides represent a relatively new concept in understanding biological oxidation chemistry. Here, we show with post-column-chemiluminescence that this sometimes remarkably stable and yet reactive species can be formed in collagen models and collagen type I when submitted to oxidative stress as exemplified by the Fenton reaction. These findings are supported by mass spectrometry and iodometry. Using (Proline-hydroxyproline-glycine)(10) (POG)(10), those hydroperoxides are stable for hours at room temperature and can give rise to free radicals in the presence of ferrous sulphate, as evidenced by EPR spin trapping with DMPO. Possible implications for biological systems are discussed with emphasis on collagen in the extracellular matrix in skin as a major type of connective tissue.

  17. Texturing studies on ? bulk crystals

    NASA Astrophysics Data System (ADS)

    Prabhakaran, D.; Subramanian, C.

    1998-08-01

    Textured crystals of 0953-2048/11/8/013/img2 have been grown by the platinum strip heater-floating zone technique. Texturing ratio and phase purity (Bi-2212) of the grown crystals were calculated from the x-ray diffraction data. Chemical compositions of the grown crystals were quantified from the inductively coupled plasma analysis. 0953-2048/11/8/013/img3 was found to be increased by 2 K for a lower level of substitution and a superconductor to semiconductor transition was observed for the higher order Y substitution. Oxygen stoichiometries of the Y substituted crystals were quantified from the iodometry titration method. Micro-twinning along the growth axis was revealed during etching studies for the cleaved crystals.

  18. Room-temperature high-spin organic single molecule: nanometer-sized and hyperbranched poly[1,2,(4)-phenylenevinyleneanisylaminium].

    PubMed

    Fukuzaki, Eiji; Nishide, Hiroyuki

    2006-01-25

    Poly[1,2,(4)-phenylenevinyleneanisylaminium] 1 was synthesized by one-pot palladium-catalyzed polycondensation of N-(3-bromo-4-vinylphenyl)-N-(4-methoxyphenyl)-N-(4-vinylphenyl)amine 3 and subsequent oxidation with the thianthrene cation radical tetrafluoroborate: compound 1 three-directionally satisfies a non-Kekulé-type pi-conjugation and the ferromagnetic connectivity of the unpaired electrons of the triarylaminium cationic radical. The average molecular weight of the polymer was 4700-5900 (degree of polymerization = 11-14), which gave a single molecular-based and globular-shaped image of ca. 15 nm diameter by atomic and magnetic force microscopies under ambient conditions. The aminium polyradical 1 with a spin concentration (determined by iodometry) of 0.65 spin/unit displayed an average S (spin quantum number) value of 7/2 even at 70 degrees C according to NMR and magnetization measurements.

  19. Analytical applications of condensed phosphoric acid-III Iodometric determination of sulphur after reduction of sulphate with sodium hypophosphite and either tin metal or potassium iodide in condensed phosphoric acid.

    PubMed

    Mizoguchi, T; Iwahori, H; Ishii, H

    1980-06-01

    Novel methods for the reduction of sulphate to hydrogen sulphide with hypophosphite-tin metal or hypophosphite-iodide in condensed phosphoric acid (CPA) are proposed. The reduction of sulphate with hypophosphite alone does not proceed quantitatively. Sulphate, however, is quantitatively decomposed with hypophosphite when tin metal or potassium iodide is used together with it. The determination of sulphur by the hypophosphite-tin metal-CPA and tin(II)-CPA methods is interfered with by copper on account of the stabilization of copper(I) sulphide, but this interference can be eliminated by adding iodide, e.g. potassium and lead salts. Alum and barytes are quantitatively decomposed within 15 min at 140 and 280 degrees , respectively. The hydrogen sulphide evolved is absorbed in zinc acetate solution at pH 4.5 and then determined by iodometry.

  20. The superconducting properties and crystal structure of YSr 2(Cu 0.9Ti 0.1) 3O 7+δ

    NASA Astrophysics Data System (ADS)

    Wuu, S. J.; Chen, D. H.; Liu, T. W.; Cheng, C. H.; Chang, C. T.; Sheen, S. R.; Wu, M. K.

    1994-06-01

    The superconducting properties and crystal structure of YSr 2(Cu 0.9Ti 0.1) 3O 7+δ were investigated. These ceramic samples were prepared in air via the solid-state method. Single-phase samples were obtained and annealed at different temperature between 300-700°C. After the annealing, YSr 2(Cu 0.9Ti 0.1) 3O 7+δ exhibited superconductivity with a transition temperature of 35 K. The magnetic susceptibility measurement and iodometry titration have revealed that the superconducting transition temperature of YSr 2(Cu 0.9Ti 0.1) 3O 7+δ increases as the hole concentration, (Cu-O) + p, and the oxygen content increase. All these samples with different oxygen content are tetragonal and in the powder X-ray results it was indicated that the Ti atoms preferentially occupy the sites of the chain copper atoms.

  1. Tc enhancement of excess Sr-doped Bi-2223 oxides by control of oxygen content

    NASA Astrophysics Data System (ADS)

    Miura, N.; Sakata, F.; Shimizu, Y.; Deshimaru, Y.; Yamazoe, N.

    1994-12-01

    The superconducting properties of excess Sr-doped 2223 phase samples, Bi 1.84Pb 0.34Sr 1.91+xCa 2.03Cu 3.06O y ( x=0.1, 0.3, 0.5, 1.0, 1.5), were examined. All the oxides as-prepared showed almost the same Tc of 109∼110 K, After heat-treatment in He at 600 °C for 3h, however, Tc increased up to 114∼115 K for the oxides with x=0.3∼, and decreased down to 102∼106 K for x=0∼0.1. The oxygen contents of the oxides as determined by iodometry increased with increasing x and slightly decreased with the heat-treatment in He. The heat treatment also brough about small increases in lattice constant of c-axis.

  2. A simple assay for lipid hydroperoxides based on triphenylphosphine oxidation and high-performance liquid chromatography.

    PubMed

    Nakamura, T; Maeda, H

    1991-09-01

    A simple and sensitive method was developed to measure total hydroperoxides. After the reduction of hydroperoxides with triphenylphosphine (TP) in cyclohexane at 30°C, the amount of triphenylphosphine oxide (TPO) produced is determined by reverse-phase or normal-phase high-performance liquid chromatography (HPLC) in combination with an ultraviolet (UV)-detector by measuring absorption at 220 or 260 nm. TPO was shown to be gener-ated stoichiometrically by reduction of known amounts of either cumene hydroperoxide or methyl 13-hydroper-oxyoctadecadienoate. For various lipids at low levels of oxidation, the peroxide values determined by this method were in good agreement with those obtained by conventional iodometry. The detection limit of TPO in HPLC using absorption at 220 nm was less than 10 pmol. Consequently, total hydroperoxides in lipids at levels corresponding to less than a peroxide value of 1 can be estimated by the TP method on a 10-mg sample.

  3. Enhanced thermoelectric figure-of-merit ZT for hole-doped Bi2Sr2Co2Oy through Pb substitution

    NASA Astrophysics Data System (ADS)

    Hsu, H. C.; Lee, W. L.; Wu, K. K.; Kuo, Y. K.; Chen, B. H.; Chou, F. C.

    2012-05-01

    Single crystals of Bi2-xPbxSr2Co2Oy (0 ≤ x ≤ 0.55) have been grown using optical floating-zone method. The chemical compositions were determined using combined electron probe microanalysis and iodometric titration. Physical properties including electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) were measured using single crystal specimens. Successful hole doping through Pb substitution is confirmed through combined iodometry titration, electrical transport, and Seebeck coefficient measurements. Significant reduction on both in-plane resistivity and thermal conductivity was found as a result of Pb substitution to the Bi site. The thermoelectric figure-of-merit ZT for x ˜ 0.55 is raised 20 folds from the undoped sample at room temperature.

  4. Voltammetric iodometric titration of ascorbic acid with dead-stop end-point detection in fresh vegetables and fruit samples.

    PubMed

    Verdini, R A; Lagier, C M

    2000-07-01

    The present work describes a method for determining ascorbic acid, which combines iodometry with a voltammetric technique to detect the end point of the titration. In addition, the validity of the method applied to natural vegetable or fruit samples was assessed. The results were compared with those obtained by an accurate method such as HPLC using UV detection. Similar values of ascorbic acid for different natural samples were obtained by means of this approach (p > 0.05). The limit of quantification was 0.1 mg. This technique presents the advantage of other electroanalytical methods such as avoiding filtration or ultracentrifugation steps, with the additional benefit of using the platinum electrodes, which are routinely used in the laboratory. These facts allow a rapid and efficient quantification of ascorbic acid with very low cost of reagents and equipment.

  5. [Investigations of centrifugal penetration of the tooth root hard substances by hydrogen peroxide].

    PubMed

    Hille, J; Glockmann, E; Lange, G

    1991-01-01

    After application of hydrogen peroxide into the root canal of extracted teeth of patients between the ages of 18 and 30 years the antiseptic could be detected on the root surface by means of iodometry and in tooth cross sections in dentine and cementum by means of staining reaction (benzidine-peroxidase solution). Out of the root canals which were apically not passable and coronally closed the first traces of the instilled 5% hydrogen peroxide appeared after 14 min 45 sec on the root surface. In the dentine a mean penetration depth of hydrogen peroxide up to 1.28 mm (apical root area), 1.45 mm (middle root third) and 1.95 mm (coronal root area) could be measured. Best results were obtained after rinsing/suction treatment of the root canal, especially in combination with low-frequency ultrasound.

  6. Critical current density and flux pinning in La 2- xPr xCa 2 x Ba 2Cu 4+2 xO z ( x=0.1-0.5) superconductors

    NASA Astrophysics Data System (ADS)

    Rayaprol, S.; Thaker, C. M.; Shah, N. A.; Kuberkar, D. G.

    2004-07-01

    Polycrystalline La 2- xPr xCa 2 xBa 2Cu 4+2 xO z (LPCaBCO) compounds with x=0.1-0.5 were synthesized by solid-state reaction method and studied by room temperature X-ray diffraction, dc resistivity, dc magnetization and iodometry. The superconducting transition temperatures in these tetragonal triple perovskite compounds increases from 32 to 62 K ( Tconset values) with increasing dopant concentration. The mixing of rare earth La 3+ and Pr 3+/4+ ions at rare earth site (La 3+) along with substitution of divalent Ca 2+ results in the shrinkage of unit cell volume. The contraction of unit cell volume due to larger ion being substituted by smaller ions, gives rise to creation of pinning centres in the unit cell leading to increase in critical current density and flux pinning.

  7. Effect of impurities in polybutene on the quality of alkenylsuccinic anhydrides

    SciTech Connect

    Yarmolyuk, B.M.; Pustovit, V.E.; Bereza, L.I.; Antonov, V.N.; Shablii, V.I.; Vititneva, L.A.

    1984-03-01

    Synthesis of alkenylsuccini anhydrides (ASAs) was carried out in thermostable ampules at 230/sup 0/C in the course of 12 hours at an MA:PB molar ratio of 1.3:1 in a medium of prepurified petroleum xylene (30%). Freshly distilled maleic anhydride and industrial specimens of polybutene were used in the experiments. It was established that the main impurities which are formed in the production of polybutene and in its processing are ions of sodium, peroxide compounds and products of decomposition of the polymerization catalyst. The concentration of sodium ion was determined by an atomic adsorption method on an A-3000 instrument, the concentration of peroxides was determined by iodometry (3), and the concentration of catalyst decomposition products was determined from the amount of mechanical impurities.

  8. Chemical amplification methods for the sequential determination of trace amounts of ruthenium by titrimetric and spectrophotometric procedures.

    PubMed

    El-Shahawi, M S; Barakat, S A

    1995-11-01

    Two simple, inexpensive and rapid iodometric and spectrophotometric procedures were developed for trace amount determination of ruthenium. The proposed methods were based on the oxidation of ruthenium(II or III) with sodium periodate at pH 2.4-3.6, masking the excess periodate with sodium molybdate. The released iodate was then allowed to react with KI at pH 3, with subsequent determination of the released iodine spectrophotometry as triiodide at 350 nm or iodometry with 0.005 M sodium thiosulphate. This procedure offers an 18- and 15-fold amplification per Ru(II) or Ru(III) ion, respectively. Alternatively, the produced iodine was extracted with CHCl(3), shaken with an aqueous solution of sodium sulphite and the produced iodide ion was then allowed to react with bromine (or sodium periodate). The released iodate was subsequently determined by iodometry or spectrophotometry after addition of KI. The bromine and sodium periodate oxidation procedures offered 90- and 360-fold amplification per ruthenium(III) ion, and 108- and 432-fold amplification per ruthenium(II) ion. Ruthenium(IV) content was determined by these procedures after prior reduction to Ru(III) with sulphurous acid. The binary mixtures Ru(II)-Ru(III); Ru(III)-Ru(IV) and Ru(II)-Ru(IV) in aqueous solution at concentration 0.05 mug ml(-1) were successfully analyzed by the developed procedures. The utility of the proposed methods for the analysis of ruthenium in its complexes was demonstrated. Natural seawater and seawater spiked with ruthenium were analyzed satisfactorily.

  9. Analytical chemistry of the citrate process for flue gas desulfurization

    SciTech Connect

    Marchant, W.N.; May, S.L.; Simpson, W.W.; Winter, J.K.; Beard, H.R.

    1980-01-01

    The citrate process for flue gas desulfurization (FGD) is a product of continuing research by the US Bureau of Mines to meet the goal of minimizing the objectionable effects of minerals industry operations upon the environment. The reduction of SO/sub 2/ in solution by H/sub 2/S to produce elemental sulfur by the citrate process is extremely complex and results in solutions that contain at least nine different sulfur species. Process solution analysis is essential to a clear understanding of process chemistry and its safe, efficient operation. The various chemical species, the approximate ranges of their concentrations in citrate process solutions, and the analytical methods evolved to determine them are hydrogen sulfide (approx. 0M to 0.06M) by specific ion electrode, polysulfides (unknown) by ultraviolet (uv) spectrophotometry, elemental sulfur (approx. 0M to approx. 0.001M dissolved, approx. 0M to approx. 0.1M suspended) by uv spectrophotometry, thiosulfate (approx. 0M to approx. 0.25M) by iodometry or high performance liquid chromatography (HPLC), polythionates (approx. 0M to approx. 0.01M) by thin layer chromatography (TLC), dithionite (searched for but not detected in process solutions) by polarography or TLC, bisulfite (approx. 0M to 0.2M) by iodometry, sulfate (approx. 0M to 1M) by a Bureau-developed gravimetric procedure, citric acid (approx. 0M to 0.5M) by titration or visible colorimetry, glycolic acid (approx. 0M to 1M) by HPLC, sodium (approx. 1.5M) by flame photometry, and chloride by argentometric titration.

  10. Insight of an easy topochemical oxidative reaction in obtaining high performance electrochemical capacitor based on CoIICoIII monometallic cobalt Layered Double Hydroxide

    NASA Astrophysics Data System (ADS)

    Vialat, Pierre; Rabu, Pierre; Mousty, Christine; Leroux, Fabrice

    2015-10-01

    A series of monometallic Layered Double Hydroxides (LDH) using electroactive cation, i.e. divalent or trivalent cobalt, was prepared by Topochemical Oxidation Reaction (TOR) under O2 atmosphere at 40 °C from pristine β-Co(OH)2 platelets. The oxidation state of the ill-defined layered materials was evaluated by coupling thermal measurements and chemical titration (iodometry). Their characterization by ancillary techniques was completed by the study of their magnetic behavior. The obtained magnetic moments suggest the presence of structural local deformation around the CoII ions, unhomogeneous charge distribution yielding to clustering effects cannot be discarded. Their pseudo-faradic properties as supercapacitor in KOH solution was thoroughly investigated by using Cyclic Voltammetry (CV), Galvanostatic Cycling with Potential Limitation (GCPL) and Electrochemical Impedance Spectroscopy (EIS) techniques. As a function of the oxygen treatment, the relative amount of CoII/CoIII was found to range into 5.3 and 13.3, which is unusually high when compared to classical LDH charge distribution. Pseudocapacitance as high as 1540 F g-1 was obtained underlining a high percentage of CoII, ≈40%, involved in electrochemical process. This high percentage is tentatively explained by an extended outer-active electrochemical surface which demonstrates that TOR is a quick and easy process to get a high pseudocapacitive performance.

  11. Iodometric microdetermination of boric acid and borax separately or in a mixture.

    PubMed

    Saxena, R; Verma, R M

    1983-05-01

    Boric acid is determined by first treating it with mannitol and then with solid potassium iodate and potassium iodide. The iodine liberated is titrated with thiosulphate. Borax is determined by reacting it with a known and excessive volume of hydrochloric acid and determining the surplus acid by iodometry. From the amount of acid consumed, the quantity of borax is calculated. Mixtures of borax and boric acid are analysed by combination of the two methods. Borax is determined first, then the mannitol procedure is applied to a second sample and the total boric acid (original plus that produced in the borax-HCl reaction) is determined iodometrically. The boric acid content of the sample is obtained by difference. The procedures can be used for determining 0.01-0.1 mmole of these substances with an average deviation of 0.1-0.4%. The end-points obtained are sharper than those for potentiometric acid-base titrations. Furthermore, the procedures are applicable at much lower concentrations.

  12. Improving the electrochemical behavior of LiCoO 2 electrode by mixed Zr-Mg doping

    NASA Astrophysics Data System (ADS)

    Xu, H. Y.; Xie, S.; Zhang, C. P.; Chen, C. H.

    A new class of LiCo 1- xZr x/2 Mg x/2 O 2 ( x = 0, 0.02, 0.06, 0.10, 0.20) materials has been synthesized using a solution-combustion method with mixed acetates/nitrates as the starting materials. The structure of the synthesized oxides was analyzed using X-ray diffraction (XRD). Iodometry titration was used to measure the oxidation state of cobalt. The electrochemical performance of LiCo 1- xZr x/2 Mg x/2 O 2 electrodes was analyzed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge cycling studies in the voltage range 2.7-4.2 V (versus Li metal). It is found that the maximum doping level ( x) is around 0.06, above which Li 2MgZrO 4 is formed as an impurity phase. The use of combined Zr-Mg doping has resulted in the decrease of the electrode impedance and increase of the specific capacity and the stability of 3.6 V plateau efficiency.

  13. An Intelligent Optical Dissolved Oxygen Measurement Method Based on a Fluorescent Quenching Mechanism.

    PubMed

    Li, Fengmei; Wei, Yaoguang; Chen, Yingyi; Li, Daoliang; Zhang, Xu

    2015-12-09

    Dissolved oxygen (DO) is a key factor that influences the healthy growth of fishes in aquaculture. The DO content changes with the aquatic environment and should therefore be monitored online. However, traditional measurement methods, such as iodometry and other chemical analysis methods, are not suitable for online monitoring. The Clark method is not stable enough for extended periods of monitoring. To solve these problems, this paper proposes an intelligent DO measurement method based on the fluorescence quenching mechanism. The measurement system is composed of fluorescent quenching detection, signal conditioning, intelligent processing, and power supply modules. The optical probe adopts the fluorescent quenching mechanism to detect the DO content and solves the problem, whereas traditional chemical methods are easily influenced by the environment. The optical probe contains a thermistor and dual excitation sources to isolate visible parasitic light and execute a compensation strategy. The intelligent processing module adopts the IEEE 1451.2 standard and realizes intelligent compensation. Experimental results show that the optical measurement method is stable, accurate, and suitable for online DO monitoring in aquaculture applications.

  14. Oxygen Knock-Out and Other Studies in -Irradiated Polycrystalline Bi-2212 Superconductor

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, S. K.; Ghosh, A. K.; Barat, P.; Sen, Pintu; Basu, A. N.; Ghosh, B.

    1997-08-01

    Bulk polycrystalline samples of Bi2Sr2CaCu2O8+x (Bi-2212) have been irradiated with 40 MeV -particles. Tc increases up to a certain dose. The increase in Tc is correlated with the knock-out of oxygen, which has been verified by the determination of the oxygen contents of the irradiated samples by iodometry. A model of the knock-out of oxygen is proposed on the basis of Monte-Carlo TRIM calculations. Resistivity versus temperature of the irradiated samples shows fairly metallic behaviour up to a certain dose. Excess conductivity analysis shows a cross-over from 2D to 3D behaviour in conductivity for the unirradiated sample. However, for irradiated samples, the critical fluctuation regime sets in. The interlayer coupling strengths decrease with the increase in the irradiation dose. The sample with the highest dose shows a nonmetallic behaviour in resistivity. A detailed analysis shows a conductivity behaviour in the nonmetallic region characteristic of three-dimensional variable range hopping of charge carriers.

  15. Search for the origin of giant Tc suppression in YBa 2Cu 3O 7- d doped simultaneously with Fe and Zn

    NASA Astrophysics Data System (ADS)

    Ogale, S. B.; Gapchup, K. M.; Lele, Pramada; Choughule, D. D.; Chikate, R. C.; Marest, G.

    1996-02-01

    In a recent paper [S.B. Ogale et al., Solid State Commun 89 (1994) 1] we reported that the superconducting transition temperature ( Tc) is suppressed drastically in YBa 2Cu 3O 7- d (YBCO) doped simultaneously with Fe and Zn as compared to an equivalent total doping of Zn or Fe, on the higher side of dopant concentration (approximately 3% or more substitution at Cu sites). In this paper, we report the results of our studies on this co-doped system, performed using the techniques of Mössbauer spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and iodometry, to explore the origin of the reported observation. The Tc suppression appears to be caused by a drop in the concentration of mobile holes in the CuO 2 planes as well as to be due to a reduced dimensionality of the system resulting from the suppression of the order parameter between the CuO 2 planes by the Fe atoms.

  16. Cefoxitin sodium compatibility with intravenous infusions and additives.

    PubMed

    O'Brien, M J; Portnoff, J B; Cohen, E M

    1979-01-01

    The compatibility and stability of cefoxitin sodium in solution with a series of frequently used intravenous infusion fluids and injectable additives were studied. Cefoxitin sodium's stability in various solutions was measured by ultraviolet spectrophotometry, iodometry, thin-layer chromatography, high-pressure liquid chromatography, ion-exchange chromatography and microbiological assay. Cefoxitin sodium was shown to maintain 90% of its initial concentration in aqueous solution for 40 hours at room temperature (25 C) and about 30 days at 5 C. The stability of cefoxitin sodium in common i.v. infusion fluids was independent of the concentrations (1 mg/ml to 400 mg/ml) and containers used, and was retained after 30 weeks storage at -20 C. Similar stability patterns were demonstrated for cefoxitin sodium in protein hydrolysate solutions and multivitamin formulations. Cefoxitin sodium was chemically and visually compatible with amikacin sulfate, gentamicin sulfate, kanamycin sulfate and tobramycin sulfate when admixed with normal saline or 5% dextrose in water injections. Cefoxitin sodium (397 mg/ml) in 0.5% lidocaine hydrochloride was stable after 26 weeks of storage at -20 C. Sodium cefoxitin is compatible with a wide variety of commonly used infusion solutions. Its stability is independent of concentration or pH within the ranges studied, and of types of common containers.

  17. Comparison of methods for inorganic sulfur speciation in a petroleum production effluent

    SciTech Connect

    Witter, A.E.; Jones, A.D.

    1998-11-01

    Multiple analytical techniques were compared for identification and quantification of inorganic sulfur species present in a sulfidic waste effluent (produced water) generated during offshore oil production. Inorganic sulfur species including sulfide, polysulfides, thiosulfate, sulfite, and sulfate were measured in produced water samples using sampled direct current polarography, differential pulse polarography, iodometry, spectrophotometry after derivatization with Ellman`s reagent, high-performance liquid chromatography after derivatization with 2,2{prime}-dithiobis(5-nitropyridine), and barium chloride precipitation of sulfate. Sulfide was determined in seven produced water samples at concentrations of 1 to 8 mM, as well as sulfate, polysulfides, and thiosulfate; sulfite was detected only occasionally in lower concentrations. Comparison of four methods used for sulfide measurement demonstrated systematic differences in results generated by various methods. Measurements of inorganic sulfur species in produced water are influenced by coupled equilibria between different chemical forms. Polysulfides exert an important role in coupling reactions between sulfur in intermediate oxidation states, and their presence can affect quantitation of these species when physical separations or standard additions perturb solution equilibria.

  18. Variation of the oxygen content of lead-containing cuprates

    NASA Astrophysics Data System (ADS)

    Hauck, J.; Altenburg, H.; Bischof, B.; Denker, S.; Droste, E.; Ipta, S.; Plewa, J.

    1991-08-01

    The variation of oxygen content with temperature and oxygen partial pressure has been studied by DTA, TGA, X-ray diffraction and iodometry for Pb 0.5SrLaCu 1.5O x, x∼5, (La, Pb) 2 SrCu 2O x, x∼5.6, Pb 2SrLaCu 2O x, x=6-7.9, Pb 2Sr 2Y 0.5Ca 0.5Cu 3O x, x=8-9.6 and PbBaSrYCu 3O x, x=7-8. The compounds Pb 2SrLaCu 2O x and Pb 2Sr 2Y 0.5Ca 0.5Cu 3O x containing CuO chains as in Ba 2YCu 3O 7 behave differently - they are semiconducting at high oxygen content. Pb 0.5SrLaCu 1.5O x and (La, Pb) 2SrCu 2O x with little volatilization of PbO can be used as precursors for the preparation of Pb 2SrLaCu 2O x.

  19. Enthalpies of Formation of La 1- xAxMnO 3± δ ( A=Ca and Sr) Measured by High-Temperature Solution Calorimetry

    NASA Astrophysics Data System (ADS)

    Rørmark, Lisbeth; Stølen, Svein; Wiik, Kjell; Grande, Tor

    2002-01-01

    High-temperature reaction calorimetry using molten lead borate as a solvent has been used to study the thermochemistry of La1-xAxMnO3 (A=Ca and Sr, 0≤x≤1). The structural properties and the oxygen stoichiometry of the calcined powders were characterized by powder X-ray diffraction, thermogravimetry, and iodometry. The enthalpy of formation of the materials from their binary constituents has been calculated from measured enthalpy of solutions. The enthalpy of formation of La1-xCaxMnO3 from the component oxides becomes more exothermic with increasing substitution level x due to the increasing valence state of Mn, and demonstrates a nearly linear dependence of the average valence state of manganese. La1-xSrxMnO3 has a significantly more exothermic enthalpy of formation from the binary constituents than the Ca-substituted materials, and demonstrates a negative deviation from ideal behavior. The present thermodynamic data are discussed in relation to the Goldschmidt tolerance factor for the perovskite structure. Finally, the phase stability of Sr- and Ca-substituted LaMnO3 is addressed in relation to the application of these materials in solid oxide fuel cells.

  20. Spectrophotometric measurement of mercaptans with 4,4'-dithiodipyridine.

    PubMed

    Egwim, I O; Gruber, H J

    2001-01-15

    In a preceding study, 4,4'-dithiodipyridine (DTDP) was shown to be superior to 5,5'-dithio-bis(2-nitrobenzoic acid) (Ellman's reagent) for spectrophotometric measurement of thiol groups in aqueous solution. (i) Sensitivity is higher because a larger absorbance increase is seen at a given thiol concentration. (ii) The intrinsic reactivity of thiolate anions for DTDP is much higher than for Ellman's reagent; thus, the reaction can be carried out at pH > or = 4.5 instead of at pH 8.0. In the present study, these advantages of DTDP were exploited for spectrophotometric measurement of thiols in organic solvent. DTDP was found to quantitatively react with nonpolar thiols when triethylamine was used as catalyst, intense light absorption (between 344 and 360 nm) was seen when the reaction was terminated with acetic acid, and the spectrophotometric responses were independent of the nonthiol portions of the mercaptans. The determination limit (10x the standard deviation of the reagent blank) was 3 microM, and the upper limit was approximately 40 microM on a typical spectrophotometer. The thiol contents of the mercaptans were independently verified by a modification of standard iodometry in which toluene/butanol or chloroform/butanol was included to dissolve nonpolar mercaptans.

  1. Triiodothyronine and thyroxine content of desiccated thyroid tablets.

    PubMed

    Rees-Jones, R W; Larsen, P R

    1977-11-01

    Triiodothyronine (T3) and thyroxine (T4) were measured by radioimmunoassay in Pronase hydrolysates of four lots each of 1- and 2-grain tablets of desiccated thyroid (Thyroid, Armour) and thyroglobulin (Proloid, Warner-Chilcott). The methodology used was verified by studies of tablets containing known quantities of T4 and T3. One grain of desiccated thyroid contained 12 +/- 1 and 64 +/- 3 microgram (mean +/- SD) of T3 and T4 per tablet, respectively (T4/T3 molar ratio, 4.3). A 1-grain tablet of thyroglobulin contained 16 +/- 2 and 55 +/- 5 microgram of T3 and T4, respectively with a T4/T3 ratio of 2.9. Two-grain tablets generally contained twice the quantity of T3 and T4 in the 1-grain preparations. The variation in T3 and T4 content between the four lots of each tablet strength for each product was 10% or less. These estimates of T3 and T4 content are 1.5- to 2-fold greater than those previously published. This difference probably results from the more sophisticated methodology now available which does not require chromatographic separation of T3 and T4 or iodometry. Using calculations based on published estimates of T4 and T3 absorption and of the T3/T4 potency ratio, it would appear that the T3 content of desiccated thyroid and thyroglobulin provide approximately 39% and 51%, respectively, of the thyromimetic activity of these two medications.

  2. Dependence of lattice parameters and T sub c on the hole concentration determined by precise measurement of the oxygen content of M sub x La sub 2 minus x CuO sub 4 minus y (M = Ba, Sr, Ca)

    SciTech Connect

    Oh-Ishi, K.; Syono, Y. )

    1991-11-01

    Systematic precise measurements of oxygen content have been performed on sintered samples of M{sub x}La{sub 2{minus}x}CuO{sub 4{minus}y} (M = Ba, Sr, Ca) superconducting oxides by both thermogravimetry and iodometry. The hole concentration, P, has been estimated by using the obtained oxygen content on the basis of charge neutrality. Lattice parameters and superconductivity of the samples have been measured by X-ray powder diffraction analysis and electrical resistivity or ac magnetic susceptibility measurement, respectively. The lattice parameter, a, depended, on both P and the average ionic radius of the La{sup 3+} site and c depended on the average ionic radius of the La{sup 3+} site, volume compensation, and oxygen defect. Orthorhombicity (defined by 2(b{minus}a)/(a+b)) depended on P. Superconductivity appeared at the same hole concentration, P = 0.10, regardless of the kind of alkaline-earth metal used. A linear relation between T{sub c} and Cu-O{sub 1} bond length within the basal plane in the structure was recognized only in the case where the hole quantity, P, was constant.

  3. An Intelligent Optical Dissolved Oxygen Measurement Method Based on a Fluorescent Quenching Mechanism

    PubMed Central

    Li, Fengmei; Wei, Yaoguang; Chen, Yingyi; Li, Daoliang; Zhang, Xu

    2015-01-01

    Dissolved oxygen (DO) is a key factor that influences the healthy growth of fishes in aquaculture. The DO content changes with the aquatic environment and should therefore be monitored online. However, traditional measurement methods, such as iodometry and other chemical analysis methods, are not suitable for online monitoring. The Clark method is not stable enough for extended periods of monitoring. To solve these problems, this paper proposes an intelligent DO measurement method based on the fluorescence quenching mechanism. The measurement system is composed of fluorescent quenching detection, signal conditioning, intelligent processing, and power supply modules. The optical probe adopts the fluorescent quenching mechanism to detect the DO content and solves the problem, whereas traditional chemical methods are easily influenced by the environment. The optical probe contains a thermistor and dual excitation sources to isolate visible parasitic light and execute a compensation strategy. The intelligent processing module adopts the IEEE 1451.2 standard and realizes intelligent compensation. Experimental results show that the optical measurement method is stable, accurate, and suitable for online DO monitoring in aquaculture applications. PMID:26690176

  4. Effet du traitement thermique sur la structure cristalline, la température critique et la ligne d'irréversibilité de Lm(SrBa)Cu 3O 6+ z (Lm=Sm, Nd)

    NASA Astrophysics Data System (ADS)

    Bellioua, Mohammed; Nafidi, Abdelhakim; El Kaaouachi, Abdelhamid; Nafidi, Ahmed

    2004-03-01

    We have studied the structural and superconducting properties of Lm(SrBa)Cu 3O 6+ z (Lm=Sm, Nd). Each of the two samples was submitted to two types of heat treatment: an annealing in oxygen [O] and a heated in argon followed by oxygen annealing [A, O]. Our iodometry measurements indicate the same total oxygen constant 6+ z, which was around 6.95±0.04 in each sample. In the case of SmSrBaCu 3O 6+ z, the treatment [A, O] increased the orthorhombicity ɛ= b- a/( b+ a) from 0 to 5.34×10 -3, indicating a tetragonal to orthorhombic structural phase transition, accompanied by an increase of 6 K in critical temperature Tc to Tc[A, O]=85 K. While in the case of NdSrBaCu 3O 6+ z, ɛ[O]= ɛ[A, O]=0 but the Tc[O]=68 K increase by 10 K. Further, there was an enhancement of the irreversibility Tp/ Tc line whatever Lm. A combination of several factors such as the change of the ionic size of the rare earth Lm, its disorder on the (Sr, Ba) site, chain oxygen ordering and increase in phase purity for the [A, O] samples may qualitatively account for the observed data. To cite this article: M. Bellioua et al., C. R. Physique 5 (2004).

  5. Effects of supersonic treatment on the electrochemical properties and crystal structure of LiMn 1.5Ni 0.5O 4 as a cathode material for Li ion batteries

    NASA Astrophysics Data System (ADS)

    Saruwatari, Hidesato; Ishikawa, Tadaomi; Korechika, Yoshiyuki; Kitamura, Naoto; Takami, Norio; Idemoto, Yasushi

    The electrochemical properties and crystal structure of LiMn 1.5Ni 0.5O 4 treated with supersonic waves in an aqueous Ni-containing solution were investigated by performing charge-discharge tests, inductively coupled plasma (ICP) analysis, scanning electron microscopy (SEM), iodometry, X-ray diffraction (XRD), powder neutron diffraction and synchrotron powder XRD. The charge-discharge curve of LiMn 1.5Ni 0.5O 4 versus Li/Li + has plateaus at 4.1 and 4.7 V. The 4.1 V versus Li/Li + plateau due to the oxidation of Mn 3+/4+ was reduced by the supersonic treatment. During the charge-discharge cycling test at 25 °C, the supersonic treatment increased the discharge capacity of the 50th cycle. Rietveld analysis of the neutron diffraction patterns revealed that the Ni occupancy of the 4b site in LiMn 1.5Mn 0.5O 4, which is mainly occupied by Ni, was increased by the supersonic treatment. This result suggests that Ni 2+ is partially substituted for Mn 3+/4+ during the supersonic treatment.

  6. Valence analysis of Pb and Cu and superconductivity of (Pb,Cu)(Sr,La) 2CuO y

    NASA Astrophysics Data System (ADS)

    Minako Shida; Eriko Ohshima; Masae Kikuchi; Masayasu Nagoshi; Yasuhiko Syono

    1996-02-01

    The Pb 1201 phases, Pb 0.5Cu 0.5Sr 2- xLa xCuO y, with x = 1.0-1.2 and Pb 0.6Cu 0.4Sr 2- xLa x CuO y, with x = 0.9-1.2 have been prepared at 1010-1015°C for 1.7-2.0 hours in flowing oxygen. To evaluate the Cu valence in the CuO 2 sheet, the Pb valence is separately determined by K 2Cr 2O 7 titration, in addition to the oxygen content determination by iodometry. The Tc (onset) rises as the oxygen content decreases due to release of the overdoping, but was not affected by La 3+ substitution for Sr 2+ and by the Pb content in the (Pb,Cu)O layer. The explanation is that the Cu valence in the CuO 2 sheet decreases as the oxygen content decreases, while the Pb valence is reduced by La 3+ substitution or the Pb content increases.

  7. Reverse flow injection spectrophotometric determination of iodate and iodide in table salt.

    PubMed

    Xie, Zhihai; Zhao, Jingchan

    2004-05-28

    A very simple and sensitive reverse flow injection method is described for the determination of iodate and iodide. The iodate reacts with excess iodide in acidic medium to form tri-iodide, which can be spectrophotometrically monitored at 351nm, and the absorbance is directly related to the concentration of iodate in the sample. The determination of iodide is based on oxidizing iodide to iodate. The calibration curve is linear in the range of 0.02-3.0mugml(-1) I with r(2)=0.9998, and the limit of detection is 0.008mugml(-1) I. The chemical and flow injection variables were studied and optimized to make the procedure suitable for quantitating iodate and iodide in table salts. It is shown that the reverse flow injection analysis could greatly improve the sensitivity and precision for determination of iodate with a relative standard deviation of 0.9%. A complete analysis, including sampling and washing, could be performed in 35s. The procedure was applied successfully to the determination of iodate and iodide in table salts, and the results were statistically compared with results determined by standard iodometry method.

  8. Synthesis and properties of disodium tetraethyleneglycol-bis-(alpha-carboxybenzylpenicillin).

    PubMed

    Kim, Y T; Jung, Y J; Kim, Y M

    1999-04-01

    Disodium tetraethyleneglycol-bis-(alpha-carboxybenzylpenicillin) (TEG-carbenicillin), a tetraethyleneglycol (TEG) diester of carbenicillin, was synthesized to develop a carbenicillin prodrug with enhanced acid stability for oral administration. Antimicrobial activities of TEG-carbenicillin tested against gram-negative Escherichia coli (TG-1) and gram-positive Staphylococcus aureus (ATCC-12228) and Bacillus subtilis (NA-1) were comparable to that of carbenicillin. Stability of the beta-lactam ring of TEG-carbenicillin was determined by iodometry at pH 6.8, pH 4.5, and pH 2.0 at varied time intervals and was compared to that of carbenicillin. In 26 hr, both of the compounds were stable at pH 6.8. At pH 4.5, about 41% of the carbenicillin was decomposed, while TEG-carbenicillin was not appreciably decomposed. At pH 2.0, carbenicillin was decomposed about 61% after 6 hr, while TEG-carbenicillin was decomposed about 21% during the same period.

  9. Structural properties of the copper oxide carbonate Ba 4CaCu 2O 6 + δCO 3 ( δ ≈ 0)

    NASA Astrophysics Data System (ADS)

    Kikuchi, Mami; Izumi, Fujio; Kikuchi, Masae; Ohshima, Eriko; Morii, Yukio; Shimojo, Yutaka; Syono, Yasuhiko

    1995-02-01

    The structure parameters of Ba 4CaCu 2O 6 + δCO 3 were refined by Rietveld analysis of angle-dispersive neutron powder diffraction data. The stoichiometric metal composition was confirmed by X-ray microanalysis. Iodometry showed that the amount of excess oxygen, δ, was nearly zero. The carbon content and infrared absorption spectrum of the compound gave evidence for the inclusion of CO 32- ions in its crystal lattice. Ba 4CaCu 2O 6CO 3 is tetragonal with the P4/mmm space group and lattice parameters of a = 5.7879(2) Å and c = 8.1409(3) Å. Ba atoms occupy positions corresponding to the A site in ABO 3 whereas Ca, Cu and C atoms are located at positions corresponding to the B site. Two copper sites are contained in the structure of Ba 4CaCu 2O 6CO 3: Cu(1) and Cu(2). If weak bonds between the Cu atoms and O atoms in the CO 32- ion are neglected, Cu(1) and Cu(2) are taken as coordinated to four O(1) atoms and two O(2) atoms, respectively. Bond-valence sum calculations showed that the oxidation state of Cu is 2.48 for Cu(1) and 1.66 for Cu(2). The splitting and large thermal parameters of O atoms contained in the CO 32- ion revealed its highly disordered orientation.

  10. Superconductivity above 30 K in [(Bi1-xMox)0.33Cu0.67]Sr2YCu2Oy: Appearance of superconductivity by transfer of holes from a block layer to a CuO2 layer

    NASA Astrophysics Data System (ADS)

    Kambe, Shiro; Sato, Eiji; Akao, Takahiro; Ohshima, Shigetoshi; Okuyama, Katsuro; Sekine, Rika

    1999-07-01

    Attention has been paid to a (Bi0.33Cu0.67)Sr2YCu2Oy compound for its uncertain superconductivity in spite of having a large Cu valence. By conducting combined experiments of iodometry, and chlorinemetry, Hall voltage measurement, Rietveld analysis, and a Discrete vibrational (DV)-Xα calculation for (Bi0.33Cu0.67)Sr2YCu2Oy, evidence of localization of holes in a (Bi0.33Cu0.67)Oy block layer was found. Those experiments suggest that about 90% of holes estimated from the Mott-Hubbard theory are localized. DV-Xα calculation revealed that the localized holes in (Bi0.33Cu0.67)Sr2YCu2Oy are not located at the apical or planar oxygen of a CuO2 layer but in the block layer. In order to transfer the localized holes from the block layer to the CuO2 layer, substitution of Mo for Bi was performed, resulting in an increase of the itinerant holes from 10 to 60 %. A bond valence sum calculation also suggested the transfer of holes from the block layer to the CuO2 layer with changes in occupancies of the oxygen sites in the block layer. Eventually, in a range of x>=0.55, it showed superconductivity above 30 K. We also discuss the origin of nonsuperconductivity of cuprates with a high Cu valence.

  11. Characterisation of Incommensurate Bi2+xSr2-xCuOz by X-Ray Powder Diffraction and Oxygen Content Determinations

    NASA Astrophysics Data System (ADS)

    Sinclair, D. C.; Irvine, J. T. S.; West, A. R.

    1990-11-01

    The composition-temperature stability region of the solid solution Bi2+xSr2-xCuOz, phase R, has been determined. At 800°C, 0.15iodometry and was independent of x. The total oxygen content z, given by z{=}6+x/2+α, was confirmed to be 6.33± 0.04, for x{=}0.30, by hydrogen reduction thermogravimetry.

  12. The physical properties of oxygen-deficient perovskite SrPbO(3-δ).

    PubMed

    Hadjarab, B; Bouguelia, A; Kadi-Hanifi, M; Trari, M

    2006-09-20

    The transport properties of oxygen-deficient perovskite SrPbO(3-δ) with mixed lead valency were investigated down to 4.2 K. The small δ-value (0.059), determined from iodometry, is due to the inert lone pair Pb(2+) that does not enjoy regular octahedral coordination in spite of collective electron behaviour. The oxide exhibits a temperature-independent magnetic susceptibility consistent with itinerant electrons. The sign of carriers like polarons is that of n-type conductivity coming from the balance charge via oxygen extraction. The thermal variation of conductivity and thermopower reveal the existence of an energy gap. The conduction mechanism occurs by polaron hopping in conformity with small activation energy. The metal-insulating transition seems to be of Anderson type, resulting from the disorder of oxygen vacancies. At low temperature, the conductivity was fitted to a variable range hopping [Formula: see text]. A comparison with SrSnO(3) will be reported. The covalency of Sn-O raises the antibonding conduction state of 5s parentage and increases the forbidden gap from 1.78 to 3.30 eV.

  13. Characteristics, Properties and Analytical Methods of Amoxicillin: A Review with Green Approach.

    PubMed

    de Marco, Bianca Aparecida; Natori, Jéssica Sayuri Hisano; Fanelli, Stefany; Tótoli, Eliane Gandolpho; Salgado, Hérida Regina Nunes

    2017-01-12

    Bacterial infections are the second leading cause of global mortality. Considering this fact, it is extremely important studying the antimicrobial agents. Amoxicillin is an antimicrobial agent that belongs to the class of penicillins; it has bactericidal activity and is widely used in the Brazilian health system. In literature, some analytical methods are found for the identification and quantification of this penicillin, which are essential for its quality control, which ensures maintaining the product characteristics, therapeutic efficacy and patient's safety. Thus, this study presents a brief literature review on amoxicillin and the analytical methods developed for the analysis of this drug in official and scientific papers. The major analytical methods found were high-performance liquid chromatography (HPLC), ultra-performance liquid chromatography (U-HPLC), capillary electrophoresis and iodometry and diffuse reflectance infrared Fourier transform. It is essential to note that most of the developed methods used toxic and hazardous solvents, which makes necessary industries and researchers choose to develop environmental-friendly techniques to provide enhanced benefits to environment and staff.

  14. Dependence of lattice parameters and Tc on the hole concentration determined by precise measurement of the oxygen content of MxLa 2- xCuO 4- y ( M = Ba, Sr, Ca)

    NASA Astrophysics Data System (ADS)

    Oh-Ishi, K.; Syono, Y.

    1991-11-01

    Systematic precise measurements of oxygen content have been performed on sintered samples of MxLa 2- xCuO 4- y ( M = Ba, Sr, Ca) superconducting oxides by both thermogravimetry and iodometry. The hole concentration, P, has been estimated by using the obtained oxygen content on the basis of charge neutrality. Lattice parameters and superconductivity of the samples have been measured by X-ray powder diffraction analysis and electrical resistivity or ac magnetic susceptibility measurement, respectively. The lattice parameter, a, depended on both P and the average ionic radius of the La 3+ site and c depended on the average ionic radius of the La 3+ site, volume compensation, and oxygen defect. Orthorhombicity (defined by {2(b - a)}/{(a + b)}) depended on P. Superconductivity appeared at the same hole concentration, P = 0.10, regardless of the kind of alkaline-earth metal used. A linear relation between Tc and CuO I bond length within the basal plane in the structure was recognized only in the case where the hole quantity, P, was constant.

  15. Effect of paste humidity on kinetics of carbothermal reduction of extruded barite and coke mixture

    NASA Astrophysics Data System (ADS)

    Salem, A.; Jamshidi, S.

    2012-08-01

    The effect of the moisture content of barite-coke paste on the kinetics of carbothermal reduction was investigated to understand the role of extrusion technique on this type of solid-gas reaction. The pastes were formulated using the typical natural barite and coke powders normally used in the industrial scale. 0.65 wt.% carboxyl methyl cellulose and different amounts of distilled water, ranging 24.3-34.4% were added to the mixed powders. The obtained pastes were then shaped by a laboratory extruder. The extrusion process was assessed by determining the total porosity of dry samples. The samples in the form of disc were isothermally heated at different temperatures in the range of 800-950 °C and the conversion of barite into barium sulfide was measured by the iodometry. The reduction data were analyzed by a modified kinetic model and the frequency factor and activation energy were calculated to evaluate the reduction mechanism. It was found that the moisture content of the paste significantly affects the active site density due to increasing contact surface area between coke and barite particles.

  16. Synthesis, physical-chemical characterization and electrochemical performance of GdBaCo2-xNixO5+δ (x = 0-0.8) as cathode materials for IT-SOFC application

    NASA Astrophysics Data System (ADS)

    Hu, Y.; Bogicevic, C.; Bouffanais, Y.; Giot, M.; Hernandez, O.; Dezanneau, G.

    2013-11-01

    GdBaCo2-xNixO5+δ (x = 0-0.8) cathode materials have been synthesized by a citrate-gel modified chemical route, by which we have achieved a high level of substitution up to x = 0.8. Oxygen stoichiometry at room temperature has been determined by iodometry and the structural evolution as a function of Ni content has been extracted from XRD patterns analysis. All compounds are orthorhombic at room temperature and a DSC analysis reveals that the high-temperature orthorhombic-to-tetragonal phase transition is observed at lower temperature as Ni substitution increases. Three compositions, with x = 0, 0.3 and 0.6, were then chosen for further characterization: high-temperature XRD has been performed confirming the abovementioned structural evolution with temperature and allowing to determine that Ni doping diminishes slightly the thermal expansion coefficient. According to 4-probe measurements, we show that these compounds present a high electronic conductivity, suitable for cathode materials. Finally, electrochemical characterization has been performed by AC impedance spectroscopy with symmetric cells using composite electrode showing an improvement of performance at intermediate substitution levels.

  17. [Qualitative and quantitative analysis of ammonium salts of hexamethylenetetramine and 1,10-phenanthroline].

    PubMed

    Bernatoniene, Rūta; Stankeviciene, Laimute; Stankevicius, Antanas; Janusiene, Laima

    2003-01-01

    By use of chemical and physicochemical methods the qualitative and quantitative analysis of bacteriostatic agents N-carbamoylmethylhexamethylenetetraamonium chloride (U-77) and 1-propyl-1,10-phenanthrolinium iodide (X-50) was carried out. The color reactions of these salts with various agents, e. g., concentrated acids, precipitants, oxidizers, indicators, ninhydrin, salts of heavy metals were assesssed. Some characteristic color reactions were found for analysis of quaternary ammonium salts. Experimental results indicate that interaction of N-carbamoylmethyhexamethylenetetraammonium chloride with silver nitrate leads to precipitate of the free silver in the form of a mirror under the proper conditions. It is a result of degradation of hexamethylenetetramine to formaldehyde and its oxidation, which is accompanied by reduction of silver ion to free silver. By use of thin-layer chromatography and ultraviolet spectrophotometry the physicochemical properties of compounds were tested. The suitability of qualitative methods, such as argentometry, mercurimetry, iodometry, extraction photometric analysis was detected. The results suggest, that the most suitable and precise method is argentometry.

  18. Study of the Effectivity of Several Tree Canopy Types on Roadside Green Belt in Influencing The Distribution Vertically and Horizontally of CO gas Emitted from Transportation Activities to Vicinity of The Road

    NASA Astrophysics Data System (ADS)

    Sulistyantara, Bambang; Nasrullah, Nizar; Sitti Fatimah, Indung; Indah Pratiwi, Prita

    2016-01-01

    High volume of vehicle leads to the increase of emission of pollutants level in major cities of Indonesia. Carbon monoxide (CO) is categorized as the main gas pollutants from transportation that are harmful to human health. Plants could be used as roadside green belt to reduce the level of pollutants emitted from the transportation. The purpose of this research is to determine tree canopy type that effectively reduce CO gas concentration, to determine the relation between tree canopy types and pollutant distribution vertically and horizontally. The research was conducted on roadside green belt of Jagorawi Highway, especially on the plot of glodogan (Polyanthea fragrans), plot of mahogany (Swietenia macrophylla) and a control plot (open filed). Air sampling was conducted to measure the concentration of CO at three elevation 1.5 m, 5 m, and 10 m at each distance 0 m, 10 m, and 30 m. Concentration of CO was analysed using Iodometri method. Vertical distribution of CO gas shows that the concentration increases with the increasing of sampling elevation on the plot of Polyalthia fragrans and Swietenia mahogany, but the control plot shows the opposite. Horizontal distribution shows that the concentration decreases at the distance 10 m on the plot of Polyalthia fragrans and Swietenia mahogany, but the concentration increases again at the distance 30 m. At the distance 10 m and an elevation 1.5 m, the highest decline percentage of CO occurs on the plot of Swietenia mahogany (45.1%), on the plot of Polyalthia fragrans is just 22.2%, while in control plot, it increases by 2.2%. At the distance 30 m and elevation 1.5 m, the concentration increased again on all of the plots. Thus roadside green belt with a thickness 10 m is not effective in reducing the concentration of CO at the distance 30 m or in residential areas.

  19. Development of a sensitive long pathlength absorbance photometer to quantify peroxides in aerosol particles (Peroxide-LOPAP)

    NASA Astrophysics Data System (ADS)

    Mertes, P.; Pfaffenberger, L.; Dommen, J.; Kalberer, M.; Baltensperger, U.

    2012-02-01

    A new off-line instrument to quantify peroxides in aerosol particles using iodometry in long pathlength absorption spectroscopy has been developed and is called peroxide long pathlength absorbance photometer (Peroxide-LOPAP). The new analytical setup features important technical innovations compared to hitherto published iodometric peroxide measurements. Firstly, the extraction, chemical conversion and measurement of the aerosol samples are performed in a closed oxygen-free (∼1 ppb) environment. Secondly, a 50-cm optical detection cell is used for an increased photometric sensitivity. The limit of detection was 0.1 μM peroxide in solution or 0.25 nmol m-3 with respect to an aerosol sample volume of 1000 l. The test reaction was done at a constant elevated temperature of 40 °C and the reaction time was 60 min. Calibration experiments showed that the test reaction with all reactive peroxides, i.e. hydrogen peroxide (H2O2), peracids and peroxides with vicinal carbonyl groups (e.g. lauroyl peroxide) goes to completion and their sensitivity (slope of calibration curve) varies by only ±5%. However, very stable peroxides have a lower sensitivity. For example tert-butyl hydroperoxide shows only 37% sensitivity compared to H2O2 after 1h. A kinetic study revealed that even after 5 h only 85% of this stable compound had reacted. The time trends of the peroxide content in secondary organic aerosol (SOA) from the ozonolysis and photo-oxidation of α-pinene in smog chamber experiments were measured. The highest amount of peroxides with 34% (assuming a MW of 300 g mol-1) was found in freshly generated SOA from α-pinene ozonolysis. Contents decreased with increasing NO levels in the photo-oxidation experiments. A decrease of the peroxide content was observed with aging of the aerosol indicating a decomposition of peroxides in the particles.

  20. Chemical pressure and other effects of strontium substitution in YBa 2Cu 3O 9-δ

    NASA Astrophysics Data System (ADS)

    Karen, P.; Fjellvåg, H.; Kjekshus, A.; Andresen, A. F.

    1991-05-01

    High quality samples of the Y(Ba 1- ySr y) 2Cu 3O 6.948(6) solid solution phase were prepared via citrate gels by mixing the components on an atomic level. The range of solid solubility is 0.00 ≤ y ≤ 0.35(3) for a 910°C firing temperature and constant oxygen content, as determined by iodometry. At standardized conditions, the limiting phase with y = 0.35(3) is in equilibrium with Y 2(Ba 0.9Sr 0.1)CuO 5 and (Sr, Y) 14Cu 24O 41, and the situation is described in terms of a tetrahedral four-component phase diagram. The slightly enhanced (anisotropic) contraction along the c axis of the unit cell, observed upon introduction of the smaller Sr atoms, is associated with apical compression of the coordination square pyramids of copper. Both the volume contraction and its anisotropy can be compared with the effects of applied pressure. In terms of chemical pressure P∗ = ɛ · y, coefficients of ɛV = 6.8(2) GPa or ɛDt = 2.4(4) GPa are obtained, depending on whether ɛ is deduced from unit cell volume V or its (tetragonal) distortion Dt. The responses of the superconducting state upon the applied and chemical pressure (the latter exerted at the Ba site) are, however, quite different, with {ΔT c}/{ΔP} = 0.7 K/GPa and {ΔT c}/{Δy} = -20(2) K. A specific feature must hence either be introduced by the real pressure (e.g., increase in carrier concentration) or by the chemical pressure [e.g., local strain effects and/or redistribution of oxygen around Cu(1) site].

  1. Remarkable influence of heat treatment on the structural and superconducting properties of (Y1-x Prx )(BaSr)Cu3O6+z

    NASA Astrophysics Data System (ADS)

    Bouallal, B.; Nafidi, A.; El Abidi, A.; El Kaaouachi, A.

    2006-09-01

    We report here on the preparation, X-ray diffraction (XRD), Seebeck effect, AC magnetic susceptibility, resistivity measurements and effect of heat treatments in the high Tc superconductor (Y1-x Prx)(BaSr)Cu3O6+z . Each sample was subject to two types of heat treatment: oxygen annealing [O] and argon annealing followed by oxygen annealing [AO]. When x increase, the oxygen content (6+z) of the samples decrease slightly from 6.9 to 6.8 as determined by our iodometry measurements. The orthorhombicity = (b -a)/(b +a) decreases to zero at xt [O] = 0.6 and xt [AO] = 0.75. These indicate a structural phase transition from orthorhombic to tetragonal at xt. Whereas, Tc decrease to zero at xc [O] = 0.7 and xc [A,O] = 0.75. Therefore the [A,O] heat treatment increase xc. Note that decrease with Tc as foreseen. However, for a given x the [AO] heat treatment makes increase (Tc). Independently of heat treatment, a increase with x, whereas b decreased to its minimum at xt. For a given x < xt, the heat treatment [AO] makes decrease a and increase. A remarkable correlations were observed between Tc (x) and (x); and between the variation δTc (x) = Tc [AO]-Tc [O] and δ (x). A combination of several factors such as decrease in the Cu (1)-apical oxygen distance; cationic order of Prx on the (Sr,Ba) site along c axis, chain oxygen ordering on (O4,O5) sites; increase in p and in-phase purity for the [AO] samples may qualitatively account for the observed data.

  2. Design of Edible Oil Degradation Tool by Using Electromagnetic Field Absorbtion Principle which was Characterized to Peroxide Number

    NASA Astrophysics Data System (ADS)

    Isnen, M.; Nasution, T. I.; Perangin-angin, B.

    2016-08-01

    The identification of changes in oil quality has been conducted by indicating the change of dielectric constant which was showed by sensor voltage. Sensor was formed from two parallel flats that worked by electromagnetic wave propagation principle. By measuring its amplitude of electromagnetic wave attenuation caused by interaction between edible oil samples and the sensor, dielectric constant could be identified and estimated as well as peroxide number. In this case, the parallel flats were connected to an electric oscillator 700 kHz. Furthermore, sensor system could showed measurable voltage differences for each different samples. The testing carried out to five oil samples after undergoing an oxidation treatment at fix temperature of 235oC for 0, 5, 10, 15 and 20 minutes. Iodometry method testing showed peroxide values about 1.99, 9.95, 5.96, 11.86, and 15.92 meq/kg respectively with rising trend. Besides that, the testing result by sensor system showed voltages values 1.139, 1.147, 1.165, 1.173, and 1.176 volts with rising trend, respectively. It means that the higher sensor voltages showed the higher damage rate of edible oil when the change in sensor voltage was caused by the change in oil dielectric constant in which heating process caused damage in edible oil molecules structure. The more damage of oil structure caused the more difficulties of oil molecules to polarize and it is indicated by smaller dielectric constant. Therefore electric current would be smaller when sensor voltage was higher. On the other side, the higher sensor voltage means the smaller dielectric constant and the higher peroxide number.

  3. Secondary organic aerosol formation during the photooxidation of toluene: NOx dependence of chemical composition.

    PubMed

    Sato, Kei; Hatakeyama, Shiro; Imamura, Takashi

    2007-10-04

    The photooxidation of toluene is a potential source of secondary organic aerosol (SOA) in urban air, but only a small portion of the compounds present in SOA have been identified. In this study, we analyzed the chemical compositions of SOA produced by photoirradiation of the toluene/NOx/air system in laboratory chamber experiments by a combination of liquid chromatography-mass spectrometry, hybrid high-performance liquid chromatography-mass spectrometry, and iodometry-spectrophotometry. The dependence of the chemical composition on the initial NOx concentration was examined at initial NO concentrations ([NO]0) of 0.2 and 1 ppmv. Fifteen semivolatile products, including aromatic and ring-cleavage compounds, were quantified. However, the quantified products comprised only a small portion ( approximately 1 wt %) of the total aerosol mass. The total SOA yield ( approximately 13 wt %), the ratio of organic peroxides to total SOA mass ( approximately 17 wt %), and the density of SOA ( approximately 1.4 g cm-3) were independent of the NOx level, suggesting that the reaction mechanisms of the formation of major SOA products at [NO]0 = 0.2 and 1 ppmv are essentially the same. The negative-ion mass spectra of SOA samples showed that ion signals attributed to hemiacetal oligomers and/or decomposition products of peroxy hemiacetal oligomers were detected in the range of mass-to-charge ratios (m/z) between 200 and 500. The highest signals were detected at m/z = 155 and 177, and these were tentatively assigned to C7 unsaturated oxacyclic oxocarboxylic acids and C7 unsaturated oxacyclic dicarboxylic acids, respectively. We conclude that the major chemical components of the aerosol are hemiacetal and peroxy hemiacetal oligomers and low-molecular-weight dicarboxylic acids.

  4. Development of a sensitive long path absorption photometer to quantify peroxides in aerosol particles (Peroxide-LOPAP)

    NASA Astrophysics Data System (ADS)

    Mertes, P.; Pfaffenberger, L.; Dommen, J.; Kalberer, M.; Baltensperger, U.

    2012-10-01

    A new off-line instrument to quantify peroxides in aerosol particles using iodometry in long path absorption spectroscopy has been developed and is called peroxide long path absorption photometer (Peroxide-LOPAP). The new analytical setup features important technical innovations compared to hitherto published iodometric peroxide measurements. Firstly, the extraction, chemical conversion and measurement of the aerosol samples are performed in a closed oxygen-free (~ 1 ppb) environment. Secondly, a 50-cm optical detection cell is used for an increased photometric sensitivity. The limit of detection was 0.1 μM peroxide in solution or 0.25 nmol m-3 with respect to an aerosol sample volume of 1 m3. The test reaction was done at a constant elevated temperature of 40 °C and the reaction time was 60 min. Calibration experiments showed that the test reaction with all reactive peroxides, i.e. hydrogen peroxide (H2O2), peracids and peroxides with vicinal carbonyl groups (e.g. lauroyl peroxide) goes to completion and their sensitivity (slope of calibration curve) varies by only ±5%. However, very inert peroxides have a lower sensitivity. For example, tert-butyl hydroperoxide shows only 37% sensitivity compared to H2O2 after 1 h. A kinetic study revealed that even after 5 h only 85% of this inert compound had reacted. The time trends of the peroxide content in secondary organic aerosol (SOA) from the ozonolysis and photo-oxidation of α-pinene in smog chamber experiments were measured. The highest mass fraction of peroxides with 34% (assuming a molecular weight of 300 g mol-1) was found in freshly generated SOA from α-pinene ozonolysis. Mass fractions decreased with increasing NO levels in the photo-oxidation experiments. A decrease of the peroxide content was also observed with aging of the aerosol, indicating a decomposition of peroxides in the particles.

  5. Poly(N-vinyl-2-pyrrolidone) elution from polysulfone dialysis membranes by varying solvent and wall shear stress.

    PubMed

    Namekawa, Koki; Matsuda, Masato; Fukuda, Makoto; Kaneko, Ami; Sakai, Kiyotaka

    2012-06-01

    Some dialysis patients are treated with post-hemodiafiltration (HDF); the blood viscosity of the patients who undergo post-HDF is higher than that of the patients who undergo conventional hemodialysis. This study aims to evaluate poly(N-vinyl-2-pyrrolidone) (PVP) elution from PSf dialysis membranes by varying solvents and high wall shear stress caused by blood viscosity. We tested three commercial membranes: APS-15SA (Asahi Kasei Kuraray), CX-1.6U (Toray) and FX140 (Fresenius). Dialysate and blood sides of the dialyzers were primed with reverse osmosis (RO) water and saline. RO water, saline and dextran solution (2.9 and 5.8 mPa s) were circulated in the blood side. The amount of eluted PVP was determined by 0.02 N iodometry. The hardness and adsorption force of human serum albumin (HSA) on the membrane surfaces were measured by the atomic force microscope. When wall shear stress was increased using dextran, the amount of PVP eluted by the 2.9 mPa s solution equaled that eluted by the 5.8 mPa s solution with APS-15SA and CX-1.6U sterilized by gamma rays. The amount of PVP eluted by the 5.8 mPa s solution was higher than that eluted by the 2.9 mPa s solution with FX140 sterilized by autoclaving. The wall shear stress increased the PVP elution from the surface, hardness and adsorption force of HSA. Sufficient gamma-ray irradiation is effective in decreasing PVP elution.

  6. Synthesis of zinc-crosslinked thiolated alginic acid beads and their in vitro evaluation as potential enteric delivery system with folic acid as model drug.

    PubMed

    Taha, M O; Aiedeh, K M; Al-Hiari, Y; Al-Khatib, H

    2005-10-01

    The aim of this study is to explore the potential of synthetic modifications of alginic acid as a method to enhance the stability of its complexes with divalent cations under physiological conditions. A fraction of algin's carboxylic acid moieties was substituted with thiol groups to different substitution degrees through conjugating alginate to cysteine to produce alginate-cysteine (AC) conjugates. Infrared spectrophotometry and iodometry were used to characterize the resulting polymeric conjugates in terms of structure and degree of substitution. Moreover, zinc ions were used to crosslink the resulting AC polymers. Folic acid loaded beads were prepared from Zinc-crosslinked AC polymers (AC-Zn) of different cysteine substitution degrees. The generated beads were then investigated in vitro for their capacity to modify folic acid release. AC-Zn polymeric beads resisted drug release under acidic conditions (pH 1.0). However, upon transfer to a phosphate buffer solution (pH 7.0) they released most of their contents almost immediately. This change in drug release behavior is most probably due to the sequestering of zinc cations by phosphate ions within the buffer solution to form insoluble chelates and, to a lesser extent, the ionization of the carboxylic acid and thiol moieties. Removal of zinc ions from the polymeric matrix seems to promote polymeric disintegration and subsequent drug release. A similar behavior is expected in vivo due to the presence of natural zinc sequestering agents in the intestinal fluids. AC-Zn polymers provided a novel approach for enteric drug delivery as drug release from these matrices complied with the USP specifications for enteric dosage forms.

  7. Structural studies of the superconducting La 3.5- x- yY yCa 2 xBa 3.5- xCu 7O z system

    NASA Astrophysics Data System (ADS)

    Subbarao, M. V.; Rajagopal, H.; Sequeira, A.; Kulkarni, R. G.

    1999-06-01

    We have investigated the influence of incorporation of Ca and Y ions on the structural and superconducting properties of La 3.5- x- yY yCa 2 xBa 3.5- xCu 7O z (0.0≤ x= y≤0.7) system by Rietveld refinement using the neutron diffraction data on five samples viz. x= y=0.0 (#1), 0.20 (#2), 0.40 (#3), 0.50 (#4) and 0.70 (#5) along with X-ray diffraction (XRD), resistivity, AC susceptibility and oxygen-content measurements. Samples with 0.20≤ x= y≤0.70 are superconducting and TcR=0 is between 56 and 79 K. Neutron data confirms (i) the occurrence of a single phase tetragonal structure with space group P4/ mmm for all the five samples, (ii) Ca and Y ions substitute onto the La sites, with concomitant displacement of La on to Ba sites, and (iii) increasing x= y from 0.0 to 0.50 decreases La-O(3) bond length from 2.516 to 2.446 Å and increases Cu(2)-O(2) bond length from 2.200 to 2.292 Å with corresponding increase in Tc from 0 to 79 K due to increasing occupancy of Y/Ca at La site. A correlation exists between the Cu(2)-O(2) and La-O(3) bond lengths and the measured Tc values of five samples. Rietveld analysis of XRD data for x= y=0.50 (#4) sample clearly shows the occupancy of Ca ions in the La sites and to small extent 0.03 in Ba sites. Such cation disordering between Ca and La,Ba may give different oxygen contents obtained from neutron data and iodometry.

  8. Chemical pressure and other effects of strontium substitution in YBa sub 2 Cu sub 3 O sub 9-. delta

    SciTech Connect

    Karen, P.; Fjellvaag, H.; Kjekshus, A. ); Andresen, A.F. )

    1991-05-01

    High quality samples of the Y(Ba{sub 1-y}Sr{sub y}){sub 2}Cu{sub 3}O{sub 6.948(6)} solid solution phase were prepared via citrate gels by mixing the components on an atomic level. The range of solid solubility is 0.00 {le}y{le}0.35(3) for a 910C firing temperature and constant oxygen content, as determined by iodometry. At standardized conditions, the limiting phase with y=0.35(3) is in equilibrium with Y{sub 2}(Ba{sub 0.9}Sr{sub 0.1})CuO{sub 5} and (Sr, Y){sub 14}Cu{sub 24}O{sub 41}, and the situation is described in terms of a tetrahedral four-component phase diagram. The slightly enhanced (anisotropic) concentration along the c axis of the unit cell, observed upon introduction of the smaller Sr atoms, is associated with apical compression of the coordination square pyramids of copper. Both the volume contraction and its anisotropy can be compared with the effects of applied pressure. In terms of chemical pressure P{sup *} = e{center dot}y, coefficients of e{sub v} = 6.8(2) GPa or e{sub D{sub t}}=2.4(4) GPa are obtained, depending on whether e is deduced from unit cell volume V or its (tetragonal) distortion D{sub t}. The responses of the superconducting state upon the applied and chemical pressure (the latter exerted at the Ba site) are, however, quite different, with {Delta}T{sub c}/{Delta}P = 0.7 K/GPa and {Delta}T{sub c}/{Delta}y = -20(2) K. A specific feature must hence either be introduced by the real pressure (e.g., increase in carrier concentration) or by the chemical pressure (e.g., local strain effects and/or redistribution of oxygen around Cu(1) site).

  9. Lanthanum substitution for barium in YBa 2Cu 3O 9-δ

    NASA Astrophysics Data System (ADS)

    Karen, P.; FjellvÅg, H.; Kjekshus, A.; Andresen, A. F.

    1991-07-01

    A detailed mapping is given for the existence range of the Y(Ba 1- yLa y) 2Cu 3O 9-δ solid solution phase with respect to y and δ. The findings are presented in the tetrahedral phase diagram of the Y(O) sbnd Ba(O) sbnd La(O) sbnd Cu(O) system. All samples were carefully prepared by citrate methods and gettering techniques giving high resolution in the degree of substitution y and oxygen content 9 - δ. The upper substitution limit of y = 0.36(2) can notably be exceeded if one at the same time allows substitution of Y by La, viz., by extending the phase region to include (Y 1- xLa x)(Ba 1- yLa y) 2Cu 3O 9-δ. For Y(Ba 1- yLa y) 2Cu 3O 9-δ, the lower limit for the oxygen content 9 - δ increases strongly with y, from 6.00(3) for y = 0.00 to, say, 6.45(3) for y = 0.20. The upper limit is approximately given as 9 - δ = 6.95 + y O,T [0.00 < y < 0.36(2)], i.e., the maximum formal Cu valency remains constant. Hence, oxygen contents well above seven per formula can be achieved, and for such samples the crystal symmetry eventually turns tetragonal, as seen by X-ray and neutron diffraction. A three-dimensional representation of the degree of orthorhombic distortion together with the parameters y and 9 - δ is made in the range where orthorhombic symmetry is adopted. For fully oxygenated samples (saturation at 340°C; PO 2 = 100 kPa; Cu valence constant: 2.30(1) according to iodometry), the symmetry change occurs at y O,T = 0.140(5); 9 - δ = 7.10. At the somewhat lower oxygen contents between 6.9 and 7.0, the domain of the orthorhombic state extends, e.g, to y O,T = 0.160(5) for 9 - δ = 6.98. An interesting consequence of this is that oxygen rich samples from the intermediate composition interval 0.14 < y < 0.16 undergo the phase transition sequence tetragonal to orthorhombic to tetragonal upon thermal removal of oxygen.

  10. [In vitro study of the antifungal activity of two chlorine derivatives to be used in antisepsis].

    PubMed

    Bianchi, P; Repetto, A; Bulletti, S; Mattiacci, P; Rossi, J; Pagiotti, R; Ribaldi, M; Schiaffella, F

    1989-01-01

    chlorine contents of the two compounds was evaluated by iodometry simultaneously with the pH of the different solutions. Useful data were obtained from the comparison of the two systems of activity assessment of the fluid and agarized substrate. It was thus found that the two compounds were equally active against the species tested. Some of these (A. fumigatus, M. gypseum, A. niger, C. albicans, C. neoformans) were less sensitive to the compounds examined (doses for cell inactivation 0.62-2.5% for product A, and O.15-1.25% for product B) where at any rate product B was more active.(ABSTRACT TRUNCATED AT 400 WORDS)

  11. Electrical conduction mechanism of LaNi{sub x}Me{sub 1−x}O{sub 3−δ} (Me = Fe, Mn)

    SciTech Connect

    Niwa, Eiki; Maeda, Hiroki; Uematsu, Chie; Hashimoto, Takuya

    2015-10-15

    Graphical abstract: Compositional dependence of (a) electrical conductivity and (b) E{sub a} for hopping conduction of LaNi{sub x}Me{sub 1−x}O{sub 3} (Me = Fe, Mn). - Highlights: • Electrical conduction mechanism of LaNi{sub x}Me{sub 1−x}O{sub 3} (Me = Fe, Mn) was investigated. • Hopping conduction model could be applied for conductivity of both specimens. • The difference of E{sub a} due to that of energy level of Fe and Mn was observed. • Hole concentration estimated by iodimetry increases with increasing Ni content. - Abstract: Electrical conduction mechanism of LaNi{sub x}Fe{sub 1−x}O{sub 3−δ} and LaNi{sub x}Mn{sub 1−x}O{sub 3+δ} expected as Sr-free new cathode material for solid oxide fuel cells was analyzed. Electrical conduction behaviors of both specimens could be well fitted by small polaron hopping conduction model. The electrical conductivity of LaNi{sub x}Fe{sub 1−x}O{sub 3−δ} increased with increasing Ni content, showing agreement with decrease of activation energy for hopping conduction. The decrease of electrical conductivity and increase of activation energy of LaNi{sub x}Mn{sub 1−x}O{sub 3+δ} were observed with increasing Ni content for 0.0 ≤ x ≤ 0.4. Further Ni substitution increased electrical conductivity and decreased activation energy for 0.4 ≤ x ≤ 0.6. It was revealed using iodometry that the difference of hole carrier density between LaNi{sub x}Fe{sub 1−x}O{sub 3−δ} and LaNi{sub x}Mn{sub 1−x}O{sub 3+δ} was small. It was suspected that the origin of the difference of electrical conduction behavior of LaNi{sub x}Fe{sub 1−x}O{sub 3−δ} and LaNi{sub x}Mn{sub 1-x}O{sub 3+δ} was difference of energy level of e{sub g} band composed of Fe 3d or Mn 3d orbitals and their overlapping quantity with O 2p and Ni 3d band.