Physical and chemical forms of radionuclides of 38S, 38Cl, 39Cl, and 82Br, produced at a high-energy proton accelerator facility

High-energy protons and neutrons produce various radionuclides in the air, mainly through the nuclear spallation of atmospheric elements. Air samples were collected from the EP-2 tunnel of the KEK 12 GeV proton synchrotron facility with a filter pack, which consisted of a membrane filter for aerosols, a Na₂CO₃-impregnated filter for acidic gases, and an activated carbon fiber filter for non-acidic gases. Sulfur-38 was found on the membrane and Na₂CO₃-impregnated filters, ³⁸Cl and ³⁹Cl were on the membrane, Na₂CO₃-impregnated, and ACF filters, and ⁸²Br was only on the ACF filter. The results on the relative abundances of aerosol and gaseous acidic components have indicated that ³⁸Cl produced by thermal neutron capture, which is the main reaction for ³⁸Cl production in the EP-2 tunnel air, are likely not to be present as aerosol or acidic gas. This was similar to the case of ⁸²Br produced by thermal neutron capture.     

The determination of boron in zirconium and zircaloy by proton activation analysis based on the 10B(p, α)7Be reaction

The determination of boron in zirconium and zircaloy based on the ¹⁰B(p, α)⁷Be reaction is described. At the 100 and 20 μg g^-1 concentration level (doped samples), instrumental analysis is feasible. At lower concentrations, ⁷Be is separated from the activities formed from zirconium and its alloying elements or impurities, by anion-exchange in hydrofluoric acid medium followed by precipitation of YF₃ and of BaBeF₄. The chemical yield of the separation was determined in several ways. The sensitivity of the method was 15 ng g^-1. For concentrations ranging from 100 to 0.15 μg g^-1, the precision ranged from 3.5 to 10.7%. The results are compared with results obtained by other methods.     

Wassergehalte von 10?2 bis 10?3% in aromatischen Kohlenwasserstoffen

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HPLC preparation of nitrate from ice cores for mass spectrometric 15N/14N measurements

Summary A method for the analysis of ¹⁵N-data of nitrate at ultratrace levels in ice cores is described. Samples are pre-concentrated using a HPLC-system. Nitrate is then reduced using the Dumas method to molecular nitrogen, which is analysed by mass spectrometry. The overall analytical precision of the method is ±0.4¹⁵N at a sample size of 35 bar l N₂. First results of deep ice-core analyses from Dome Summit, Greenland, are given.     

Myosin-catalyzed ATP hydrolysis elucidated by 31P NMR kinetic studies and 1H PFG-diffusion measurements

We conducted ³¹P NMR kinetic studies and ¹H-diffusion measurements on myosin-catalyzed hydrolysis of adenosine triphosphate (ATP) under varied conditions. The data elucidate well the overall hydrolysis rate and various factors that significantly impact the reaction. We found that the enzymatic hydrolysis of ATP to adenosine diphosphate (ADP) was followed by ADP hydrolysis, and different nucleotides such as ADP and guanosine triphosphate acted as competitors of ATP. Increasing ATP or Mg²⁺ concentration resulted in decreased hydrolysis rate, and such effect can be related to the decrease of ATP diffusion constants. Below 50 °C, the hydrolysis was accelerated by increasing temperature following the Arrhenius’ law, but the hydrolysis rate was significantly lowered at higher temperature (~60 °C), due to the thermal–denaturation of myosin. The optimal pH range was around pH 6–8. These results are important for characterization of myosin-catalyzed ATP hydrolysis, and the method is also applicable to other enzymatic nucleotide reactions.     

Spuren von Antimon (10?2 bis 10?6 %) in Tellur als Halbleitermaterial

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Measurement of the radioactivity of 238U, 226Ra, 210Pb, 228Th, 232Th, 228Ra, 137Cs and 40K in tea using gamma-spectrometry

The aim of the present work was to determine the concentration of radionuclides in all kinds of tea available at the local Egyptian market. Radioactivity of the nuclides ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²²⁸Th, ²³²Th, ²²⁶Ra, ¹³⁷Cs and ⁴⁰K were measured in tea by direct γ-ray spectrometry using HPGe detector and their mean values were 16.0±5.3, 3.1±0.7, 34.3±3.4, 3.4±1.2, 3.0±0.6, 3.1±0.8, 0.9±0.2 and 623±25 Bq·kg⁻¹, respectively.     

Die Bestimmung von 175Hf, 172Hf, 172Lu und 169Yb

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Tacticity measurements on polypropylene sulphide by 13C-NMR spectroscopy

Determination of tacticity of polypropylene sulphide is studied by NMR. The measurements made by ¹³C-NMR are compared with those obtained by ¹H 100 MHz NMR on corresponding selectively deuterated polymers. The good correlation between the two sets of results shows that stereoregularity of polypropylene sulphide can be easily found with 5 per cent precision.     

Helium-3 in Argon im Konzentrationsbereich von 10?5 bis 10?6 ppm (Volumen)

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Molecular structure of methyl-10,14,19,19-tetramethyl-4-oxo-20-oxahexacyclo [15.3.1.16.18.06.15.09.14017.21]docosane-10-carboxylate

The synthesis of methyl-10,14,19,19-tetramethyl-4-oxo-20-oxahexacyclo[15.3.1.1^6.18.0^6.15.0^9.140^17.21] docosane-10-carboxylate III is performed and its molecular structure is determined. Compound III C₂₇H₄₀O₄ crystallizes in the monoclinic system with the cell parameters as follows: a = 12.8081(11) ?, b = 7.0384(6) ?, c = 12.8904(12) ?, β = 105.828(2)^o, P2₁ space group, Z = 2, d = 1.273 mg/m³.     

Surface-enhanced Raman spectroscopy of 12CN− and 13CN− adsorbed at silver electrodes

Measurements are reported of the surface-enhanced Raman of ¹²CN and ¹³CN (and of isotopically labelled mixtures) adsorbed at silver electrodes. The spectra are shown to arise from a complex species whose coordination number does not change with electrode potential. This species is probably a [Ag(CN₂)]^? entity having C_2v symmetry; at very negative potentials a reduced form of this complex [Ag(CN)₂]^2? coexists with the formally Ag¹ species at the surface. The shifts in band position are interpreted in terms of changes in the bond character of the adsorbed CN^? species. The spectrum of water coadsorbed with CN^? is also markedly dependent on the charge density of the adsorbed CN^? groups.     

Die chromatographische Trennung und Bestimmung von 51Cr, 54Mn, 60Co und 59Fe

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13C relaxation measurements of molecular motion in micellar solutions

Measurements have been made of the ¹³C nuclear magnetic resonance longitudinal relaxation time T₁ in micellar solutions of sodium lauryl sulphate with different concentration of added sodium chloride. The purpose of the experiment was to see what effect added electrolyte had on the motion of the paraffin chains. It is shown that the methylene group next to the polar head gains more freedom as the electrolyte concentration is increased. The molecular motions inside the micelle do not change.     

CAS SCF Cl calculations for the 3Σ−g, 1Σ+g, 3Σ+u, and 5Δu states of Sc2

CAS SCF CI (SD) calculations have been carried out for the ³Σ^?_g, ¹Σ⁺_g, ³Σ⁺_u, and ⁵Δ_u states of Sc₂ using large gaussian basis sets. The ³Σ^?_g, ¹Σ⁺_g, and ³Σ⁺_u states arise from the ²D(4s² 3d¹) + ²D(4s² 3d¹) limit of Sc₂ and are found to be only weakly bound (D_c ≈ 0.06 eV and R_c ≈ 8.0a₀). The ⁵Δ_u state arises from the ²D(4s² 3d¹) + ⁴F(4s¹ 3d¹ 4p¹) atomic limit. This state is found to be strongly bound relative to its limits (D_c ≈ 0.8 eV and R_c ≈ 7.0a₀).     

A simplified polarographic determination of dissolved Cd(II) at the 10?10 M level

Summary To simplify the determination of dissolved Cd(II) in water and sea water-like solutions at the 10^–10–10^–9 M level an automated concentration step was developed consisting of percolating about 21 of sample over a column with an immobilized reagent (ED₃A) and dissolving the trapped cadmium in 0.1 M nitric acid. A concentration factor of 50 or more is easily obtained. Recoveries are about 90%. With anodic stripping differential pulse polarography as a final determination technique overall standard deviations are in the range of 0.1–0.4·10^–10 Mol of Cd.On leave from Lisbon University, Portugal     

Zur Darstellung von hochspezifischem 64Cu, 65Ni und 56Mn

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