Microdistributions of Electrolytic Alloys and Their Components

Microdistributions of Cu–Ni and Cu–Co alloys electrodeposited from pyrophosphate; Ni–Cu, from sulfate–chloride and pyrophosphate–ammonium; Cu–Zn, from pyrophosphate and cyanide; Cu–Cd, from sulfate and pyrophosphate; and Ni–Cd, Ni–Co–Cd, and Zn–Cd, from sulfate, sulfate–chloride, pyrophosphate, chloride–ammonium, and acetate electrolytes are studied. The coatings' microprofile depends on the kinetics of reduction of each component and mutual influence of electrochemical processes at the cathode. Copper accelerates and cadmium inhibits the reduction of the second component of alloys, no matter the electrolyte type, reduction kinetics, and metal nature. In antileveling conditions, the diffusion-controlled Cu reduction accelerates the reduction of the second component of alloys and ensures deposition of coatings whose microprofiles are more uniform than expected from diffusion limitations only. Depolarizing action of Cu during the Cu–Zn deposition from a cyanide electrolyte can completely neutralize differences in the rates of supply of reduced metal ions; hence a constant chemical composition of the coating over its microprofile. Inhibiting action of the diffusion-controlled Cd deposition provides for leveling properties of electrolytes from which Ni–Cd, Ni–Co–Cd, and Zn–Cd alloys are deposited; the chemical composition of these deposits is nonuniform over their microprofiles.     

Towards the understanding of the spectroscopic behaviour of the C–H oscillator in C–HO hydrogen bonds: the effect of solvent polarity

The effect of solvent polarity versus specific C–HO contacts on the vibrational νC–H mode is studied using CHCl₃ as a model system. Ab initio SCI–PCM calculations show that the overall shift of the νC–H band, sometimes ascribed to the C–HO hydrogen bonding, can in fact be explained by the electrostatic interaction with a dielectric environment. The presence of a new νC–H band – assigned to the C–HO bonded forms – remains as the most reliable evidence of C–HO hydrogen bonding.     

Polarographic and voltammetric determination of trace amounts of 2-nitronaphthalene

The polarographic behaviour of 2-nitronaphthalene was investigated by DC tast polarography (DCTP) and differential pulse polarography (DPP), both at a dropping mercury electrode, and differential pulse voltammetry and adsorptive stripping voltammetry, both at a hanging mercury drop electrode. Optimum conditions have been found for the determination of 2-nitronaphthalene by the given methods in the concentration ranges of 2×10^–6–1×10^–4, 2×10^–7–1×10^–4, 1×10^–8–1×10^–4 and 2×10^–9–1×10^–8 M, respectively. Practical applicability of these techniques was demonstrated by the determination of 2-nitronaphthalene in drinking and river water after its preliminary separation and preconcentration using liquid–liquid and solid-phase extraction with limits of determination of 3×10^–10 M (drinking water) and 3×10^–9 M (river water).     

Nanoaggregates of ABC-type triple hydrophilic block copolymers by binding of cationic surfactant

A triple hydrophilic block copolymer comprised of poly(ethylene oxide), poly(sodium 2-acrylamido-2-methylpropanesulfonate), and poly(methacrylic acid) (PEO–PAMPS–PMAA) does not form a micelle by itself when it is dissolved in water. However, in the previous paper, we fabricated the nanoaggregates of PEO–PAMPS–PMAA and cationic surfactant, such as cetyltrimethylammonium chloride (CTAC), by insolubilizing the anionic PAMPS and/or PMAA blocks of the polymer with CTAC only at high pH. In this paper, we fabricated the nanoaggregates of dodecyltrimethylammonium chloride (DTAC) and PEO–PAMPS–PMAA in a wide range of pH to examine the effect of ionization of the PMAA blocks of the polymer on the aggregates formation of PEO–PAMPS–PMAA. The properties of the nanoaggregates are affected by the ionization of PMAA block of the polymer. DTAC (C12 alkyl chain) was employed instead of CTAC (C16 alkyl chain) to reveal the effect of alkyl chain length of surfactant on the aggregate formation of PEO–PAMPS–PMAA. The properties of PEO–PAMPS–PMAA nanoaggregates also depend on the structure of surfactant. The binding of DTAC to PEO–PAMPS–PMAA was monitored by electrophoresis measurements, while the formation of DTAC/PEO–PAMPS–PMAA nanoaggregates was confirmed by scanning electron microscopy, dynamic light scattering measurements and fluorescence spectroscopy.     

Neutron activation analysis of asbestos from Canada

Concentrations of Al, Au, Br, Ce, Cl, Co, Cr, Fe, K, La, Mg, Mn, Na, Ni, Sb, Sc, Sm, Srm and V were determined in 6 samples of asbestos from Canada. They were equal to (in ppm): Al 1660–3430; Au 0.03–0.04; Br 3.1–11.7; Ce 1.7–4.8; Cl 116–331; Co 35–83; Cr 200–2060; Fe 29300–42200; K 125–867; La 0.28–1.03; Mg 24–25.9%; Mn 418–545; Na 364–1610; Sb 0.65–1.46; Sc 3.73–5.57; Sm 0.09–0.3; Sr 26.7–41.4; V 8.4–14.3. Five toxic elements were found in asbestos; Cr, Mn, Ni, Sb and V.     

ZnO nanorods decorated calcined Mg–Al layered double hydroxides as photocatalysts with a high adsorptive capacity

The nanocomposites of magnesium–aluminium–carbonate–layered double hydroxides (Mg–Al–CO₃–LDHs) and ZnO nanorods were prepared via a homogeneous precipitation process. The presence of ZnO nanorods made the calcined Mg–Al–CO₃–LDHs, the strong adsorptive adsorbents for anions, have a photocatalytic activity. Both Mg–Al–CO₃–LDHs and the nanocomposites with various ZnO/Mg–Al–CO₃–LDHs mass ratios from 0.5:1 to 3:1 were characterized by X-ray diffraction, transmission electron microscope and UV–vis diffuse reflectance spectra. The nanocomposites quickly adsorbed the anionic dyes such as acid red G (ARG) without the light illumination, and the adsorbed dyes on the recovered nanocomposites were then degraded in a separated photocatalytic reactor. The adsorption ability of the nanocomposites and their photocatalytic activities for the removal of ARG were evaluated by the Fourier transform infrared spectra and UV–vis extinction spectra. The sample at 3:1 ZnO/Mg–Al–CO₃–LDHs mass ratio was shown to have higher photocatalytic efficiencies.     

Spectroscopic studies of the behaviour of the AgNO3−HNO3 — Tetrabutyl dithiopyrophosphate extraction system

A very efficient extraction of silver with tetrabutyl dithiopyrophosphate (TBDTPP) is followed by dramatic changes in the structure of the extractant molecule. The IR and NMR spectroscopic studies have revealed that in the presence of Ag⁺ and NO ₃ ^– ions the TBDTPP molecule rearranges first into a molecule containing a P–S–P bridge and one P=O group instead of P–O–P and P=S, respectively, and then into a molecule containing two P–S–C and two P=O groups at a P–O–P bridge.     

Preparation of conjugates of peptides imitating part of the antigen-determinant section of protein VP1 of foot-and-mouth disease virus A12 with various supports

The preparation of conjugates of peptides 143–148, 153–159, 149–159, 146–159, and 143–159, imitating a section of a protein of the foot-and-mouth disease (FMD) virus of type A₁₂, with bovine serum albumin, with. a copolymer of N-vinylpyrrolidone with acrylic acid, and with a copolymer of N-vinylpyrrolidone with maleic anhydride is described. The dependence of the degree of conjugation on various factors is discussed.V. I. Lenin Tadzhik State University, Dushanbe. Institute of Immunology, Ministry of Public Health of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 516–519, July–August, 1990.     

Voltammetric Determination of Sulfide Ions

Procedures were proposed for the voltammetric determination of S^2– at a mercury-film electrode. They are based on the oxidation of S^2– at –0.79 to –0.80 V and on the reduction of HgS, the product of the oxidation of S^2–, at –0.76 to –0.96 V in a 1 M NaOH solution. The anodic and cathodic currents are linear functions of S^2– concentration in the ranges from 1 × 10^–5 to 1 × 10^–4 M and from 2 × 10^–6 to 1 × 10^–4 M, respectively.     

A study of the chemiluminescence behavior of myoglobin with luminol and its analytical applications

A chemiluminescence signal at 425 nm was observed when ferric state myoglobin was mixed with luminol in alkaline medium. Because the signal was remarkably enhanced in the presence of Fe(CN)₆ ^4–, analytical applications were investigated in a flow-injection system. The increase in chemiluminescence was linearly dependent on myoglobin concentration in the range 0.1 to 100 nmol L^–1, and the limit of detection was 0.04 nmol L^–1 with relative standard deviation 3.2% (3). It was also found that binding of Mb with the ligands CN^–, SCN^–, and F^– significantly inhibited the chemiluminescence reaction. The linear dynamic ranges for the ligands were 1.0–300.0, 0.1–3.0, and 0.5–100.0 nmol L^–1, and the limits of detection (S/N=3) 0.4, 0.04, and 0.2 nmol L^–1, for F^–, CN^–, and SCN^–, respectively. The relative standard deviations were 5.32%, 6.13%, and 3.38% for 0.1 nmol L^–1 CN^–, 0.5 nmol L^–1 SCN^–, and 1.0 nmol L^–1 F^–, respectively. At a flow rate of 2.0 mL min^–1 the assay could be accomplished in 1 min, including sampling and washing. The method has been successfully applied to the determination of myoglobin in human urine and F^– in water samples. A possible mechanism of chemiluminescence production by myoglobin and luminol is presented.     

Synthesis,electrochemical and magnetic properties of new macrocyclic copper(II) complexes derived from 2,6-diacetyl-4-4-methylphenol

A series of binuclear macrocyclic copper(II) complexes [Cu2Lm,n](ClO4)2·xH2O have been prepared in which the two copper(II) ions are placed in two geometrically distinct co-ordination environments. The macrocycles with two 2,6-bis(iminomethyl)-4-methylphenol entities combined through two different lateral chains, –(–CH2–)–m and –(–CH2–)–n (m = 2 or 3, n = 2 to 5) were synthesized by stepwise cyclization. Cyclic voltammetry shows the presence of two reduction couples: CuIICuII CuICuII and CuIICuI CuICuI. The comproportionation constants, Kcom, for the mixed valence CuICuII complexes have been determined electrochemically. The Kcom value increases in the order of the macrocycles: (L2,2)^2–<(L2,3)^2–<(L2,4)^2–<(L2,5)^2– and (L3,3)^2–<(L3,4)^2–<(L3,5)^2–. Cryomagnetic investigations (80–300K) reveal a moderately strong antiferromagnetic spin exchange between the copper(II) ions within each complex (J = –210 to –390 cm–1).     

Determination of131I,134Cs,137Cs in plants and cheese after Chernobyl accident in Roumania

Various samples from the south-east region of Roumania/greens, fodder, cheese/were analyzed for¹³¹I,¹³⁴Cs and¹³⁷Cs concentrations in May and July 1986 by -ray spectrometry. The concentrations are reported in nCi. kg^–1 wet weight. For greens, a considerable decrease was observed for¹³¹I/to 3.0–7.0 nCi. kg^–1/,¹³⁴Cs/to 0.5–2.0 nCi.kg^–1/ and¹³⁷Cs /to 1.0–4.0 nCi. kg^–1/ from the first half /5–15 May/ till the end of May 1986. For cheese, maximum values were measured between 5 and 15 May /sheep cottage cheese: 500–800 nCi.kg^–1 for¹³¹I, 25–50 nCi. kg^–1 for¹³⁴Cs, 40–80 nCi. kg^–1 for¹³⁷Cs/; at the beginning of July a considerable decrease /to 5–10 nCi. kg^–1 for¹³¹I, 1.2–2.0 nCi.kg^–1 for¹³⁴Cs, 2.2–3.0 nCi. kg^–1 for¹³⁷Cs/ was observed. In autumn 1986 a small increase up to 2.0–3.0 nCi. kg^–1 for¹³⁴Cs and 3.4–5.0 nCi. kg^–1 for¹³⁷Cs /in November/ was reported. The population's internal possible contamination was strongly limited by the authorities' severe control of the food-stuff.     

Comparison of GC-ICP-MS and HPLC-ICP-MS for species-specific isotope dilution analysis of tributyltin in sediment after accelerated solvent extraction

This study describes a direct comparison of GC and HPLC hyphenated to ICP–MS determination of tributyltin (TBT) in sediment by species-specific isotope dilution analysis (SS-IDMS). The certified reference sediment PACS-2 (NRC, Canada) and a candidate reference sediment (P-18/HIPA-1) were extracted using an accelerated solvent extraction (ASE) procedure. For comparison of GC and LC methods an older bottle of PACS-2 was used, whilst a fresh bottle was taken for demonstration of the accuracy of the methods. The data obtained show good agreement between both methods for both the PACS-2 sediment (LC–ICP–IDMS 828±87 ng g^–1 TBT as Sn, GC–ICP–IDMS 848±39 ng g^–1 TBT as Sn) and the P-18/ HIPA-1 sediment (LC–ICP–IDMS 78.0±9.7 ng g^–1 TBT as Sn, GC–ICP–IDMS 79.2±3.8 ng g^–1 TBT as Sn). The analysis by GC–ICP–IDMS offers a greater signal-to-noise ratio and hence a superior detection limit of 0.03 pg TBT as Sn, in the sediment extracts compared to HPLC–ICP–IDMS (3 pg TBT as Sn). A comparison of the uncertainties associated with both methods indicates superior precision of the GC approach. This is related to the better reproducibility of the peak integration, which affects the isotope ratio measurements used for IDMS. The accuracy of the ASE method combined with HPLC–ICP–IDMS was demonstrated during the international interlaboratory comparison P-18 organised by the Comité Consultatif pour la Quantité de Matière (CCQM). The results obtained by GC–ICP–IDMS for a newly opened bottle of PACS-2 were 1087±77 ng g^–1 Sn for DBT and 876±51 ng g^–1 Sn for TBT (expanded uncertainties with a coverage factor of 2), which are in good agreement with the certified values of 1090±150 ng g^–1 Sn and 980±130 ng g^–1 Sn, respectively.     

Solvent extraction and separation of some lanthanides and americium by extraction chromatography in the system Aliquat-336 — LiNO3 and HNO3

Summary The liquid-liquid extraction of Nd, Eu, Ho, and Am nitrates by means of the radiotracer method in the system tri-caprylmonomethyl ammonium nitrate /Aliquat-336/ — lithium nitrate and nitric acid was investigated.The mixture of tracer quantities of Eu–Am, Nd–Pr, Sm–Pm, Gd–Eu, Er–Ho, Tm–Er, Yb–Tm, and Lu–Tm were separated by column partition chromatography.

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Lösungsmittelextraktion und Trennung einiger Lanthanide und Americium durch Extraktions-chromatographie im System Aliquat-336 — LiNO₃ und HNO₃

Zusammenfassung Es wurde die Flüssig-Flüssig-Extraktion von Nd-, Eu-, Ho- und Am-Nitraten mit Hilfe radioaktiver Markierung im System Tri-caprylmonomethyl-ammoniumnitrat-/Aliquat-336/-Lithiumnitrat und Salpetersäure untersucht.Die Markierungsgemische von Eu–Am, Nd–Pr, Sm–Pm, Gd–Eu, Er–Ho, Tm–Er, Yb–Tm und Lu–Tm wurden durch Säulen-Verteilungs-Chromatographie getrennt.

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Extraction par solvant et separation de quelques lanthanides et d'americium par chromatographie d'éxtraction dans le système «Aliquat-336, LiNO₃, HNO₃»

Sommaire On a étudié, au moyen de la méthode des radiotraceurs, l'éxtraction liquide-liquide de nitrates de Nd, Eu, Ho et Am dans le système «nitrate de tri-caprylmonométhyl ammonium [Aliquat-336], nitrate de lithium, acide nitrique».Les mélanges de Eu–Am, Nd–Pr, Sm–Pm, Gd–Eu, Er–Ho, Tm–Er, Yb–Tm et Lu–Tm à la dose des traceurs radioactifs, ont été résolus en leurs composants chromatographie de partage sur colonne.

     

The effect of high pressure on the ion pair equilibrium constant of alkali metal fluorides: A spectrophotometric study

Bromophenol blue indicator was used in UV-visible spectrophotometric measurements to study ion association constants of alkali metal fluorides. The equilibrium constants for the ion pair formation of the alkali metal fluorides were determined as a function of ionic strength at one atmosphere pressure and 25°C. The effect of pressure on these association constants was measured at a constant total ionic strength of 1.0 mol-kg^–1 over a pressure range of 1 to 2000 atmospheres at 25°C. The pressure dependences of the stoichiometric association constants of the alkali metal fluorides are given by: lnK _LiF ^* =0.77–2.47×10^–4P–2.12×10^–8P²; lnK _NaF ^* =0.53–1.08×10^–4P–1.66×10^–8P²; lnK _KF ^* =0.24–4.41×10^–5P–7.15×10^–8P²; lnK _RbF ^* =–0.17–8.65×10^–5P–4.51×10^–8P²; and lnK _CsF ^* = –0.37–1.14×10^–4P–6.82×10^–8P², where P is the pressure in atmospheres. The stoichiometric molar volume and compressibility changes for ion pair formation of the alkali metal fluorides were evaluated from the pressure dependence of K _MF ^* data. The thermodynamic association constants were also calculated making use of activity coefficient data from the Pitzer equations. The partial molal volume and compressibility changes for ion pair formation of each alkali metal fluoride are reported.     

Analysis of High-Purity Volatile Compounds

The current status of the analysis of high-purity volatile substances is considered. Two types of impurities in high-purity volatile substances were distinguished: molecularly dissolved substances and suspended particles. The main factors that restrict the limiting capabilities of analytical techniques were revealed. The attained detection limits were 10^–8–10^–10% for metal impurities, 10^–4–10^–8% for organic substances, 10^–5–10^–9% for water, and 10^–5–10^–7 for permanent gases. Suspended particles of 0.04–0.003 m in size were determined by light scattering.     

Capacitance of the Electrical Double Layer on Liquid Hg–Ga Alloy in Aqueous Solutions

Differential capacitance curves on an Hg–Ga electrode are obtained in aqueous solutions of various composition. An Hg–Ga electrode containing 2.1 at. % Hg to a high accuracy models electrochemical properties of a liquid Hg electrode at negative charges. This result can justify the approach according to which studying liquid In–Ga, Tl–Ga, Cd–Ga, and Pb–Ga alloys permit qualitative characterization of lyophilic properties of corresponding solid alloys.     

Determination of oxygen in fluoride glass by proton activation analysis

Oxygen was determined in three kinds of ZrF₄-based fluoride glass [ZrF₄–BaF₂–GdF₃–AlF₃ (ZBGA), ZrF₄–BaF₂–LaF₃–YF₃–AlF₃–LiF–NaF (ZBLYALN) and ZrF₄–BaF₂–LaF₃–YF₃–AlF₃–LiF (ZBLYAL)] used for fabricating optical fiberby¹⁸O(p, n)¹⁸F reaction without significant nuclear interference. The main long life⁹⁶Nb nuclide was produced by the⁹⁶Zr(p,n) reaction in a non-destructive analysis of ZBGA-fluoride glass and reduced by using a coincidence system with Ge(Li) and NaI(T1) detectors. Substoichiometric separation of¹⁸F was also used to determine oxygen in fluoride glass, especially in glass containing yttrium as a component element because the⁸⁹Zr produced by the⁸⁹Y(p,n) reaction is a positron emitter, the same as¹⁸F. It was confirmed that the oxygen concentration in fluoride glass was 13–2460 ppm related to the loss by scattering.     

Neutron Activation Analysis of Bottom and Fly Oil Ash Leachates

Seven samples of oil fly and bottom ashes were leached with water using a Canadian standard test method for shake extraction of solid waste. The concentrations of 20 elements in the leachates were determined by the computerized systematic instrumental absolute neutron activation analysis. The ranges of concentrations (in ppm) found for the elements in the leachates were: Al (3–526), Ba (0.5–6), Ca (100–695), Cl (13–59), Co (1–6.3), Cr (0.2–6.6), Cs (0.03–0.4), Eu (0.003–0.01), Fe (28–690), K (42–464), La (0.3–49), Mg (214–3150), Mn (1.2–20), Na (88–4050), Sb (0.04–0.4), Sc (0.003–0.07), Sr (1.2–23), U (0.07–1), V (1.2–4540) and Zn (2.3–200). These findings were compared with the maximum concentrations allowed for these elements by Canadian regulations. The concentrations of Cr and U were found to be higher than their permissible limits on 7 occasions. The purpose of this study was to determine the background levels of different elements in oil ash leachates, in order to evaluate their potential impact on underground water.     

Sizes and Conformation of the Molecules of DNA–Surfactant Complexes in Dilute Solutions and on the Atomic Smooth Substrates

The conformations of the molecules of DNA–surfactant complexes in dilute solutions and on the atomic smooth surfaces of mica and highly oriented pyrolytic graphite were comparatively studied by the methods of isothermal diffusion, electric birefringence, and atomic force microscopy. The DNA–surfactant complexes were deposited onto the substrates from a chloroform solution. The number of particles of the DNA–surfactant complex on the substrate was changed by varying the concentration of the initial solution within three orders of magnitude. The particles of a shape close to ellipsoidal, 25–70 nm in diameter and 2–4 nm high, were observed at the lowest concentration of DNA–surfactant solution on the mica substrate. The shape and size of these particles correspond to those of a single DNA–surfactant complex, calculated from its translational diffusion coefficient and the time of orientational relaxation in dilute solutions. An increase in the number of molecules deposited onto the substrate leads to an increase in the characteristic sizes of DNA–surfactant complex particles observed by the atomic force microscopy. This may be associated with the aggregation of DNA–surfactant complexes.