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.     

Researches on 2, 1, 3-thia- and selenadiazole

4-Hydroxy-, 4-hydroxy-5-methyl-, 4-hydroxy-7-methylbenzo-2,1,3-thiadiazoles are polymorphous.4-Hydroxybenzo-2,1,3-thiadiazole (I), 4-hydroxy-5-methyl- and 4-hydroxy-7-methylbenzo-2, 1, 3-thiadiazoles (II and III) melt at 114–115°, 110–112°, 100–102° C, respectively, after recrystallization from water [2–4], but after recrystallization from petrol ether [5] they melt at 128–129°, 124–125°, and 119–120° C [5]. In this connection we recrystallized these phenols repeatedly from petrol ether after recrystallizing them from water, and their melting points rose as expected [5]. On the other hand, the compounds with melting points 128–129°, 124–125°, 119–120° C (ex petrol ether), after repeated crystallization from water melted at 114–115°, 110–112°, 100–102° C, respectively.For Part XXXVIII see [1].     

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.     

Synthesis and absorption spectra of 3,5-diaryl-1,2,4-triazoles

1,2,4-Triazoles with symmetrical tolyl substituents were obtained from the corresponding 1,3,4-oxadiazoles by reaction with formamide and subsequent hydrolysis of the resulting formyl derivatives; 1,2,4-triazoles with unsymmetrical substituents were obtained from iminoesters and hydrazides of acids. A set of bands of the triazole ring at 1470–1480, 1390, 1270–1290, 1140–1150, and 725–750 cm^–1 and of NH vibrations at 2400–3200, 1580–1620, and 830–900 cm^–1 are characteristic for the IR spectra of these triazoles. The UV spectra of the triazoles are characterized by phenyl ring absorption at about 200 nm and a band of electron transitions between the phenyl and triazole rings at 230–290 nm.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1682–1685, December, 1977.     

Determination of 19 elements in mineral waters by coprecipitation with PbS and by neutron activation analysis

Concentrations of Ag, Al, Ba, Br, Cl, Cu, I, In, K, La, Mg, Mn, Na, Sb, Sn, Sr, U, V and Zn were determined in 34 samples of mineral waters from Canada and from 9 other countries. The concentrations of elements which were frequently determined ranged (in ppb): Ag 0.1–6, Al 3–173, Cu 2–137, La 0.04–10, Mg 9–1140, Mn 0.1–99, Sb 1–50, V 0.01–2.6 and Zn 3–613.     

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.     

Negative ion formation in compounds relevant to SF6 decomposition in electrical discharges

Dissociative and nondissociative electron attachment in the electron impact energy range 0–14 eV are reported for SOF₂ SOF₄, SO₂F₂, SF₄, SO₂, and SiF₄ compounds which can be formed by electrical discharges in SF₆. The electron energy dependences of the mass-identified negative ions were determined in a time-of-flight mass spectrometer. The ions studied include F^– and SOF ₂ ^–* from SOF₂; SOF ₃ ^– and F^– from SOF₄; SO₂F ₂ ^–* , SO₂F^–, F ₂ ^– , and F^– from SO₂F₂; SF ₄ ^–* and F^– from SF₄; O^–, SO^–, and S^– from SO₂; and SiF ₃ ^– and F^– from SiF₄. Thermochemical data have been determined from the threshold energies of some of the fragment negative ions. Lifetimes of the anions SOF ₂ ^–* , SO₂F ₂ ^–* , and SF ₄ ^–* are also reported.     

Extraction of actinium with di (2-ethylhexyl) phosphoric acid from hydrochloric and nitric acid solutions

The extraction of actinium with HDEHP from Cl^– and NO ₃ ^– systems has been investigated. It was found that extraction of actinium from HCl solutions is much better than from HNO₃ solutions. Stability constants of the actinium complexes Ac(X^–)²⁺, X^–=Cl^– or NO ₃ ^– , were determined. Our results show that actinium formed less stable complexes with Cl^– than with NO ₃ ^– ligands.     

Oxomolybdenum(VI) and (V) complexes with 6–methyl-4–hydroxypyrimidinyl hydrazones

Dioxomolybdenum(VI) complexes [MoO2(L)H2O] and oxomolybdenum(V) complexes [Mo2O3(LH)2Cl2] (where LH2=hydrazones derived from 6–methyl-4–hydroxy-2–hydrazinopyrimidine with salicylaldehyde, 5–methyl-, 5–chloro-, 5–bromo-, 3–methoxy-salilcylaldehyde, or 2–hydroxy-1–naphthaldehyde) have been prepared and characterised by spectroscopic and physico-chemical methods. The MoVI complexes are diamagnetic octahedral structures, whilst the MoV complexes are paramagnetic and probably dimeric, via oxobridging.     

Über die Synthese eines im Gift von Bombina variegata vorkommenden hexapeptid-diamids

Zusammenfassung Mittels der p-Nitrophenylestermethode wurde das Hexapeptiddiamid der Sequenz Ala–Glu–His–Phe–Ala–Asp(NH₂)₂, durchwegsl-Aminosäure, stufenweise aufgebaut. Das synthetische Produkt war mit einem aus Unkengift (Bombina variegata) isolierten Peptid strukturell identisch.

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Using the p-nitrophenylester method the hexapeptide diamide Ala–Glu–His–Phe–Ala–Asp(NH₂)₂ was synthesized froml-amino acids. This product was identical with a natural peptide, which had previously been isolated from the venom ofBombina variegata.

     

Trace element determination in seawater by ICP-SFMS coupled with a microflow nebulization/desolvation system

Direct and simultaneous determination of Al, Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Sb, U, V and Zn in diluted (1:10 v:v) seawater from the Antarctic Ocean and the Venice Lagoon at the ng mL^–1 and pg mL^–1 level has been performed by using an inductively coupled plasma sector field mass spectrometer (ICP-SFMS). Samples were analysed by using a PFA microflow nebulizer coupled with a desolvation system or a PFA microflow nebulizer coupled with a Teflon spray chamber, respectively. Measurements were carried out at low (LR, m/m=300), medium (MR, m/m=3,000) and high (HR, m/m=7,500) resolutions depending on the studied isotope. To avoid contamination, sample pre-treatment was carried out in a clean laboratory equipped with a Class 100 vertical laminar flow hood. Concentration ranges (minimum–maximum in ng mL^–1) found in the Antarctic seawater samples (in depth profiles) were: Ag 0.0004–0.0018, As 0.69–1.32, Cd 0.031–0.096, Co 0.018–0.065, Cr 0.18–0.46, Cu 0.04–1.58, Fe 0.13–1.63, Mn 0.02–0.12, Mo 5.97–12.46, Pb 0.007–0.074, Sb 0.033–0.088, U 0.5–1.9, V 0.6–2.5 and Zn 0.16–0.80. Concentration ranges (min–max in ng mL^–1) found in the Venice Lagoon water samples (temporal profile from a benthic chamber experiment) were: Al 0.24–0.61, Ag 0.007–0.031, As 1.42–2.27, Cd 0.050–0.182, Co 0.440–1.461, Cr 0.15–0.34, Cu 0.81–2.46, Fe 0.25–1.66, Mn 11.6–31.7, Mo 6.50–10.6, Pb 0.047–0.225, Sb 0.240–0.492, U 1.7–3.3, V 1.3–2.8 and Zn 5.20–21.5. The detection limits range between 0.06 pg mL^–1 for Ag and U to 15 pg mL^–1 for Fe. In order to check the accuracy of the analytical procedure, measurements of the trace elements in a certified reference material (coastal Atlantic seawater, CASS-4-NRCC) were compared with the certified values. In addition, the results from the Antarctic and Venice Lagoon samples were compared with those obtained by using different analytical techniques.     

Trace elements analysis in rice

Various rice species, marketed in Austria, were analyzed for their Se, Cr, Ni, Rb, Fe, Co, Cs, Ag and Hg contents by neutron activation analysis. The concentration values found for Se ranged between 0.023 and 0.265 ppm, for Cr 0.540–1.875 ppm, for Ni 0.359–0.965 ppm, for Rb 1.604–6.400 ppm, for Fe 24.3–139.8 ppm, for Co 0.026–0.055 ppm, for Cs 0.016–0.032 ppm, for Ag 0.0006–0.0034 ppm, for Hg 0.003–0.023 ppm. Statistical analysis showed in the majority of cases that there is a significant difference in Se, Cr, Ni, Rb, Fe, Co, Hg contents but not in Cs. Highest values of Se and Fe were found in rice from Belgium /long seed, super patna/, whereas the Cr concentration was the highest in rice from Thailand /siam patna/. Ni was highest in rice from Uncle Ben's, Rb in Kresto from USA.     

Phase Equilibria and Nonequilibrium Structures in the Sodium Di-2-Ethylhexyl Phosphate–Decane–Water System

Phase equilibria and nonequilibrium structures in the sodium di-2-ethylhexyl phosphate (NaSDEHP)–decane–water system were studied. It was found that, at a certain component ratio, a microemulsion and a liquid crystal phase are present in the system. The phase diagram was plotted, describing two- and three-phase equilibria: NaSDEHP and water solution in decane–microemulsion, microemulsion–liquid crystals, NaSDEHP and water solution in decane–microemulsion–liquid crystals, and NaSDEHP and water solution in decane–liquid crystals. The viscosity of NaSDEHP microemulsion was measured. It was shown that the viscosity increases significantly with an increase in the ratio of sodium hydroxide and di-2-ethyhexyl phosphoric acid molar concentrations from 0.6 to 1.0. Formation of the third liquid (microemulsion) phase in the vicinity of the oil–water interface was found upon the transfer of NaSDEHP from one phase to the other.     

Magnetische Untersuchungen an Übergangsmetallarseniden

Zusammenfassung Die magnetischen Susceptibilitäten von Legierungen aus den quasibinären Systemen TiAs(h)–VAs, TiAs(h)–CrAs und VAs–CrAs werden mittels einer magnetischen Waage im Bereich von 293° K–1423° K gemessen. Insbesondere wird der Übergang von Paramagnetismus zu Antiferromagnetismus, der mit dem Wechsel von der NiAs- zur MnP-Struktur einhergeht, studiert.

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By means of a magnetic balance magnetic susceptibilities of alloys from the quasi-binary systems TiAs(h)–VAs, TiAs(h)–CrAs, and VAs–CrAs were measured in the range from 293° K–1423° K. The transition from paramagnetism to antiferromagnetism, connected with the change from the NiAs-type to the MnP-type, was closely studied.

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Mit 7 Abbildungen     

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.     

Voltammetric Determination of Rubeanic Acid

Procedures for the voltammetric determination of rubeanic acid (RA) at a mercury-film electrode were proposed. They are based on the oxidation of RA at –0.70 to –0.80 V or on the reduction of mercury sulfide, the product of RA oxidation, at –0.82 to –0.85 V (versus a saturated silver–silver chloride electrode) in a 1 M NaOH solution. The oxidation and reduction currents are linear functions of RA concentration in the ranges from 9 × 10^–6 to 3 × 10^–4 M and from 5 × 10^–6 to 3 × 10^–4 M, respectively.     

Radioisotope excited EDXRF analysis of sediment core samples from the southern part of the Black Sea +

In all 43 sediment samples were collected as gravity cores in depthfrom 70 to 150 cm, from the 20 sampling sites of the continental slope ofthe southern part of the Black Sea, during 1978. The samples were quantitativelyanalyzed by radioisotope excited energy dispersive X-ray fluorescence spectrometry(EDXRF) using fundamental parameter technique (FTP). The investigated sedimentsamples were the organic rich-mud components of the core samples, which wereknown as rich in metals. The metal concentration ranges were as follows: Ca(3.1–12.9%), Ti (1000–2000 µg/g), V (40–150 µg/g),Cr (30–200 µg/g), Mn (200–1500 µg/g), Ni (25–100µg/g), Cu (20–70 µg/g), Zn (20–50 µg/g), Br(15–670 µg/g), Rb (5–90 µg/g), Sr (80–700 µg/g),Y (10–20 µg/g), Mo (10–111 µg/g), Zr (20–190µg/g), Cd ( <1–5 µg/g), Sb ( <1–5 µg/g),I (10–430 µg/g), Ba (100–1650 µg/g), La (5–18µg/g), Ce (12–38 µg/g) and Nd (6–17 µg/g). Thesediment cores systematically collected in 1978 by Mineral Research and ExplorationInstitute of Turkey (MTA) are the oldest available sediment samples from theTurkish coastline of the Black Sea. Therefore, the results may be used asreferences for monitoring possible future metal pollution.     

Selective Oxidation of Glucose to Gluconic Acid over Bimetallic Pd–Me Catalysts (Me = Bi,Tl, Sn,Co)

Catalytic properties of bimetallic Pd–Bi, Pd–Tl, Pd–Sn, and Pd–Co catalysts supported on C (from plum stones) and SiO₂ were studied in the reaction of glucose oxidation to gluconic acid. Catalysts modified with Bi show the best selectivity and activity. The results obtained from research on 5% Pd–5% Bi/C and 5% Pd–5% Bi/SiO₂ catalytic systems were compared with the results for a commercial catalyst containing 1% Pt–4% Pd–5% Bi supported on active carbon (Degussa). For both Pd–Bi/support catalysts and 1% Pt–4% Pd–5% Bi/C, similar selectivity in the reaction of glucose oxidation was observed. XRD studies proved the presence of intermetallic compounds BiPd and Bi₂Pd, which probably increase the selectivity of PdBi/SiO₂ catalysts.     

Effect of temperature on the selectivity of the extraction of lanthanides with dibutylphosphoric acid from thiocyanate solution

Extraction coefficients and separation factors of all lanthanides were determined in the system: dibutylphosphoric acid /HDBP/ - 3M NH₄NCS, in the temperature range of 15–50 °C. The values for the separation factors for such pairs as: Gd–Tb and Er–Tm, are higher than 4, those for the pair of Tb–Dy are higher than 3, and those for the La–Ce, Pm–Sm, Dy–Ho, Ho–Er and Tm–Yb pairs are higher than 2. The influence of temperature on the separation factors of light /La–Gd/ and heavy /Gd–Lu/ lanthanides is discussed and compared with that observed for the extraction from the nitric acid solutions. The results are also discussed in the light of the double-double effect and outer-, vs. inner-sphere complexation in the lanthanide series.