Prompt gamma rays from triton-induced reactions on oxygen and their use for analysis

Triton-induced reactions on oxygen were studied with a view to using the prompt γ-rays for analytical purposes. Five γ-rays were found to be potentially useful, of which three had a high intensity, the n(1, 0), n(2, 0) and p(1, 0) γ-rays, the other two being the n(3, 0) and the unresolved pair α(1, 0)–α(2, 0). The γ-rays are labelled according to the conventions(a,b), wheres is the light prompt product and the γ-photon is emitted by de-excitation from levela tob in the heavy product nucleus. The method had a relative precision of 2 to 3.5% for surface oxygen concentrations from 50 to 3 μg/cm². The sensitivity with 1 900 keV tritons was 0.13 μg/cm² on surfaces of steel or copper which did not yield interfering γ-rays, but 0.45 μg/cm² on aluminium where interfering γ-rays were emitted.     

Die Bestimmung von53Mn,Welches in Meteoritischem Material Durch Kosmische Strahlung Erzeugt Wurde,mit Hilfe der Neutronenaktivierung

Among a number of stable and unstable nuclides formed in material exposed to cosmic radiation the spallation nuclide⁵³Mn (T=2·10⁶ a) is investigated in meteoritic manganese by combined techniques of neutron activation and advanced γ-spectrometry. The need for an economic use of precious meteorites is so ensured best. Intense neutron bombardment transforms the long-livedK-emitter⁵³Mn into⁵⁴Mn, which is detected by its 0.84 MeV γ-rays. Using the (n,γ) cross section—recently derived byMillard—⁵³Mn-values in the range of 60–600 dpm/kg (10⁻¹¹ g/g) are found in a larger number of iron meteorite samples, which are only 1–3 g in weight. The determination is very specific and under appropriate conditions unaffected by side reactions. The attempt to use the⁴⁴Ti (n,γ)⁴⁵Ti reactions for the analysis of spallogenic titanium failed, because the σ_therm of⁴⁴Ti was found to be unexpectedly low (10 barns). Additionally,⁴⁵Sc was determined after (n,γ) reaction by the⁴⁶Sc γ,γ-cascades.      

Modifying silica with viologenic groups

Modification of silica with viologenic groups is described. N,N′-Diallyl-γ,γ′-dipyridinium dibromide obtained by the reaction of allyl bromide with γ,γ′-dipyridyl was hydrosilylated with triethoxysilane followed by copolycondensation of the synthesized bis(3-triethoxysilylpropyl)-γ,γ′-dipyridinium dibromide with tetraethoxysilane.     

Carbon-carbon bond formation and annulation reactions using trimethyl and triethyl orthoformates

Synthetic utility of trimethyl and triethyl orthoformates for carbon-carbon bond formation is briefly surveyed, particularly in relation to dialkoxymethylation, carbonyl transposition-homologation, and cycloalkenone annulation reactions recently reported from the authors’ and other laboratories. The complex mechanisms involved in the one-step and two-step annulations of rigid β,γ- and γ, δ-unsaturated ketones have been discussed.     

Measurements of the thermal neutron cross-sections and resonance integrals for 186W (n,γ) 187W and 98Mo (n,γ) 99Mo reactions

The thermal neutron cross-sections and resonance integrals of the ¹⁸⁶W (n,γ) ¹⁸⁷W and ⁹⁸Mo (n,γ) ⁹⁹Mo reactions in the thermal and 1/E regions, respectively, of a thermal reactor neutron spectrum have been experimentally determined by the activation method using ¹⁹⁷Au (n,γ) ¹⁹⁸Au reaction as a single comparator. The high purity natural W, Mo, and Zr foils; and Au wire diluted in aluminum, were irradiated without Cd shield in two neutron irradiation sites, characterized with different values for the thermal-to-epithermal flux ratios, f at the Second Egyptian Research Reactor (ETRR-2). The induced activities in the samples were measured by high-resolution γ-ray spectrometry with a calibrated germanium detector. Thermal neutron cross-sections for 2200 m/s neutrons and resonance integrals for the ¹⁸⁶W (n,γ) ¹⁸⁷W and ⁹⁸Mo (n,γ) ⁹⁹Mo reactions have been obtained relative to the reference values, σ₀ = 98.65 ± 0.09 b and I ₀ = 1500 ± 28 b for the ¹⁹⁷Au (n,γ) ¹⁹⁸Au reaction. The necessary correction factors for thermal neutron and resonance neutron self-shielding effects, and the epithermal flux index (α) were taken into account in the determinations. The results obtained were: σ₀ = 38.43 ± 0.4 b and I ₀ = 502 ± 65 b for ¹⁸⁶W (n,γ) ¹⁸⁷W, and σ₀ = 0.137 ± 0.014 band I ₀ = 6.47 ± 0.8 for ⁹⁸Mo (n,γ) ⁹⁹Mo. These results are discussed and compared with previous measurements and evaluated data in literature. The traditional method of determining thermal cross-sections and resonance integrals via neutron irradiation with and without Cd shield in one irradiation position was avoided in this work by neutron irradiation without Cd shield in at least two different neutron irradiation positions. This method provides alternative way for determining thermal cross-sections and resonance integrals simultaneously.     

The isomeric ratios in photonuclear reactions of natural tellurium induced by bremsstrahlungs with endpoint energies in the giant dipole resonance region

We have determined the isomeric ratios in ¹²⁰Te(γ, n)^119m,gTe, ¹²²Te(γ, n)^121m,gTe, ¹²⁸Te(γ, n)^127m,gTe and ¹³⁰Te(γ, n)^129m,gTe photonuclear reactions of natural tellurium induced by bremsstrahlungs with end-point energies in the giant dipole resonance (GDR) region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated were measured with spectroscopic system consisting of 8192 channel analyzer and high-energy resolution (180 keV at gamma ray 1,332 keV of ⁶⁰Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results were discussed and compared with those of other authors.     

Integral invariants for high-symmetry open-shell molecules

A method for calculating the energies of electronic states arising from a degenerate open shellγ ^N in terms of integral invariants H^k(γ,γ) is presented. The calculation proceeds from expansions for the electron repulsion integrals 〈mm/nn〉 on degenerate orbitals ofγ symmetry in terms of H^k(γ,γ). The energies of states for theγ ^N electronic configurations with dimγ≤3 (e^N and t^N configurations) are tabulated. Institute of Catalysis, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 2, pp. 183–195, March–April, 1998. This work was supported by RFFR grants No. 96-03-01167 and 96-03-34035.     

The isomeric ratios in photonuclear reactions of natural barium induced by bremsstrahlungs with endpoint energies in the giant dipole resonance region

We have determined the isomeric ratios in ¹³⁰Ba(γ, n)^129m,gBa, ¹³²Ba(γ, n)^131m,gBa and ¹³⁴Ba(γ, n)^133m,gBa photonuclear reactions of natural barium induced by bremsstrahlungs with end-point energies in the giant dipole resonance region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated were measured with spectroscopic system consisting of 8192 channel analyzer and high-energy resolution (180 keV at gamma ray 1332 keV of ⁶⁰Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results were discussed and compared with those of other authors.     

Dibenzo-18-crown-6 modified with kojic acid fragments

Diazonium salts were prepared by diazotization of 4′-amino-, 4′,4″-, and 4′,5″-diaminodibenzo-18-crown-6. Their coupling products with kojic acid (5-hydroxy-2-hydroxymethyl-γ-pyrone) were synthesized for the first time: 4′-(6-aza-5-hydroxy-2-hydroxymethyl-γ-pyronyl)-, 4′,4″-di-(6-aza-5-hydroxy-2-hydroxymethyl-γ-pyronyl)-, and 4′,5″-di-(6-aza-5-hydroxy-2-hydroxymethyl-γ-pyronyl)-dibenzo-18-crown-6. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 415–416, September–October, 2006.     

Enantiocontrol in intramolecular cyclopropanation of diazoketones. Conformational control of metal carbene alignment

Diazo ketones with γ or δ double bonds undergo catalytic intramolecular cyclopropanation. These reactions occur with high enantiocontrol when catalyzed by copper semicorrins and bis-oxazolines, but low enantiocontrol characterizes reactions catalyzed by a broad selection of chiral dirhodium(ii) carboxamidates. The reverse stereocontrol occurs for intramolecular cyclopropanation of allylic and homoallytic diazoacetates and diazoacetamides. This divergence is explained by conformational control of carbonyl alignment (syn oranti to the metal) of the metal carbene intermediate. Dedicated to Academician of the RAS O. M. Nefedov (on his 65th birthday). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 995–998, May, 1997.     

Photon activation analysis of carbon in glasses for fiber amplifiers by using the flow method for the rapid separation of 11C

Summary We have studied the photon activation analysis of carbon in InF₃-based fluoride, chalcogenide and tellurite glasses for fiber amplifiers, and especially the nuclear interference from a matrix produced by (γ,n), (γ,2n), (γ,p) and (n,γ) reactions and a flow method for the rapid and simple separation of ¹¹C. A chemical separation technique is indispensable for determining carbon, because seventeen radionuclides are observed in these glasses. The flow method can sequentially be undertaken, the fusion of an irradiated sample with an oxidizer, the conversion of ¹¹C into ¹¹CO₂, and the absorption of ¹¹C in ethanolamine solution. We used a mixture of Pb₃O₄ and B₂O₃ as the oxidizer. There is interference with the ¹¹C measurement because ¹⁸F and ⁶⁸Ga are produced in fluoride and chalcogenide glasses by the ¹⁹F(γ,n), ²³Na(γ,αn) and ⁶⁹Ga(γ,n) reactions, respectively, and also absorbed in ethanolamine solution. Therefore, this flow method can only be applied to tellurite glasses. The chemical yield provided by the flow method was close to 100% when determining carbon in Japanese Iron and Steel Certified Reference Materials (JSS) by using lithium carbonate as a standard sample. We determined that the carbon concentrations in four kinds of tellurite glass were 7 to 14 ppm.     

Enhanced ternary 1:2 host–guest complexation of amino-γ-cyclodextrins with 2-anthracenecarboxylic acid

The complexation behavior of 6-amino-6-deoxy-γ-cyclodextrin (CD), 6^A,6^X-diamino-6^A,6^X-deoxy-γ-CDs and 3^A-amino-3^A-deoxy-altro-γ-CD with 2-anthracenecarboxylic acid (AC) was studied by NMR, UV–vis and circular dichroism spectroscopy. These modified γ-CD derivatives were found to form stable 1:2 host-guest ternary complexes with AC in aqueous solution. Compared with native γ-CD, the primary-face-aminated γ-CDs exhibited remarkably enhanced overall association constants as a result of the additional electrostatic interactions between the oppositely charged host and guest. In contrast, the ternary complex formation of the secondary-face-aminated γ-CD with AC was hindered.     

Integral invariants for high-symmetry open-shell molecules.

A numerical procedure for expanding electron repulsion integrals 〈mm|nn〉 on degenerate molecular orbitals of γ symmetry (γ=e, t, g, h) into integral invariants (reduced matrix elements) H^k(γ, γ) is suggested. The latter are analogous in their sense to Slater-Condon parameters F^k(l, l) for atoms with an electronic configuration l^N. The method is applicable to nonlinear molecules of arbitrary symmetries, including “not readily reducible” groups. G. K. Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 1, pp. 3–17, January–February, 1998. This work was supported by RFFR grants No. 96-03-01167 and 96-03-34035.     

Impact of environmental conditions on the sorption behavior of radionuclide 63Ni(II) onto hierarchically structured γ-MnO2

A novel hierarchically structured γ-MnO₂ has been synthesized using a simple chemical reaction between MnSO₄ and KMnO₄ in aqueous solution without using any templates, surfactants, catalysts, calcination and hydrothermal processes. As an example of potential applications, hierarchically structured γ-MnO₂ was used as adsorbent in radionuclide ⁶³Ni(II) treatment, and showed an excellent ability. The effects of pH, ionic strength, temperature, humic acid (HA) and fulvic acid (FA) on the sorption of radionuclide ⁶³Ni(II) to hierarchically structured γ-MnO₂ have been investigated by using batch techniques. The results indicated that the sorption of ⁶³Ni(II) on γ-MnO₂ is obviously dependent on pH values but independent of ionic strength. The presence of HA/FA strongly enhances the sorption of ⁶³Ni(II) on γ-MnO₂ at low pH values, whereas reduces ⁶³Ni(II) sorption at high pH values. The sorption of ⁶³Ni(II) on γ-MnO₂ is attributed to inner-sphere surface complexation rather than outer-sphere surface complexation or ion exchange. The thermodynamic parameters (ΔH ⁰, ΔS ⁰, ΔG ⁰) are also calculated from the temperature dependent sorption isotherms, and the results suggest that the sorption of ⁶³Ni(II) on γ-MnO₂ is a spontaneous and endothermic process.     

Synthesis and phase behavior of aqueous poly(N-isopropylacrylamide-co-acrylamide), poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) and poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate)

Poly(N-isopropylacrylamide) (PNIPAM) and random copolymers of Poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) (PNIPAM-HEMA), poly(N-isopropylacrylamide-co-acrylamide) (PNIPAM-AAm), and poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) (PNIPAM-DMAA) with various volume fractions γ of NIPAM were synthesized by radical polymerization. The phase behavior of the polymers in water was investigated by means of optical transmittance and dynamic light scattering. With decreasing γ, the cloud point temperature T _cp for PNIPAM-HEMA decreased whereas the T _cp for both PNIPAM-AAm and PNIPAM-DMAA increased. Increase of hydrodynamic radius around T _cp, which resulted from the aggregation of the globules of each polymer, was observed from dynamic light scattering. The relationships between the reciprocal of T _cp of the polymer solutions and 1-γ were linear for the three copolymers in the experimental range of 0.65<γ<1. The results are discussed from the aspect of the interaction parameters of copolymer solutions.     

Partitioning technique procedure revisited II: Application to the Stark and Zeeman problems in light atoms

We show that the modified partitioning procedure can be applied to study the spherical and nonspherical Stark effect in the hydrogen atom and the spherical quadratic Zeeman effect in H^-, the helium atom and He‐like ions: Li⁺⁺, Be⁺⁺, etc. We present ground‐state energy values for γ (in a.u.) in the interval 0.001 ≤ λ ≤ 0.2 (a.u.= 5.142·10⁹ volts/cm) and for magnetic field γ (in a.u.) in the interval 0.1 ≤ γ ≤ 1.0 (a.u. = 2.353·10⁹ gauss). We compare our results to values available in the literature; they are, in general, better than those obtained by other methods. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study of the isomeric ratios in photonuclear reactions of natural holmium and lutetium induced by bremsstrahlungs with endpoint energies in the giant dipole resonance region

We have determined the isomeric ratios in ¹⁶⁵Ho(γ, n)^164m,gHo and ¹⁷⁵Lu(γ, n)^174m,gLu photonuclear reactions of natural holmium and lutetium induced by bremsstrahlungs with end-point energies in the giant dipole resonance (GDR) region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated were measured with spectroscopic system consisting of 8192 channel analyzer and high-energy resolution (180 keV at gamma ray 1332 keV of ⁶⁰Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results were discussed and compared with those of other authors.     

Discontinuities in the surface structure of alcohol-water mixtures

Summary Surface tension determinations by the capillary rise method were obtained, at 25 ‡C and at frequent concentration intervals, for two binary systems: methyl alcohol-water and ethyl alcohol-water. The data were plotted as a function of (γ_w−γ _a ) X_b ^a/(γ_w−γ) versus 100 X _b ^a , where X _b ^a denotes the mole fraction of alcohol in the bulk of the solution, and γ _w , γ _a , and γ are surface tensions of water, alcohol, and alcohol-water mixture, respectively. The plots display twelve and eleven straight-line segments for MeOH-H₂O and EtOH-H₂O system, respectively, over their entire concentration ranges. For each concentration range for which the plot is rectilinear, the alcohol-water aggregates in the surface are of one composition. Tentative stoichiometric compositions of the binary aggregates are derived.

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Zusammenfassung Die Oberfl?chenspannung von zahlreichen bin?ren Methyl- und ?thylalkohol-Wasser-Gemischen wurde innerhalb weiter Konzentrationsgrenzen bei 25 ‡C bestimmt, wobei die Kapillarsteigh?henmethode angewandt wurde. Die Daten wurden als folgende Funktion des Molprozents, 100 X _b ^a , des Alkohols graphisch dargestellt: (γ_w−γ _a ) X_b ^a/(γ_w−γ), wobei γ _w , γ _a und γ für die Oberfl?chenspannung des Wassers, des Alkohols und des Gemisches stehen. Die Kurve des Methylalkohol-Wasser-Gemisches besteht aus zw?lf, die des ?thylalkohol-Wasser-Gemisches aus elf linearen Bereichen. Jedem Bereich entspricht ein genau definiertes Alkohol-Wasser-Aggregat in der Oberfl?che der L?sung. Versuchsweise sind verschiedene st?chiometrische Zusammensetzungen der bin?ren Alkohol-Wasser-Aggregate abgeleitet.

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Research supported by the Bureau of Ships, U.S. Navy, and communicated at the XXth International Congress of Pure and Applied Chemistry, Moscow. U.S.S.R., 12–18 July, 1965.     

Non-selectivity in the reaction of levoglucosenone with the sulfinyl allyl carbanion

Condensation of levoglucosenone with the carbanion ofrac-allyl phenyl sulfoxide, in contrast with reactions of this anion with the majority of other unsaturated ketones, proceeds without regio- or enantioselectivity to give a (1.0–1.8): 1 mixture of products of both 1,2- and 1,4-γ-addition of the allylic residue. Each product is a (1.2–1.6): 1 mixture of epimers at the asymmetric sulfur atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 157–159, January, 1999.     

Measurement of reaction cross-sections for 64Ni(n, γ) 65Ni at E n = 0.025 eV and 58Ni(n, p) 58Co at E n = 3.7 MeV

The reaction cross-sections for ⁶⁴Ni(n, γ) ⁶⁵Ni at E _n  = 0.025 eV and ⁵⁸Ni (n, p) ⁵⁸Co at E _n  = 3.7 MeV have been experimentally determined using activation and off-line γ-ray spectrometric technique. The thermal neutron flux used is from the thermal Column of the reactor APSARA at BARC, Mumbai, whereas the neutron energy of 3.7 MeV is from the ⁷Li(p, n) reaction at Pelletron facility, TIFR, Mumbai. The ⁶⁴Ni(n, γ) ⁶⁵Ni and ⁵⁸Ni(n, p) ⁵⁸Co reactions cross-sections from present work are compared with the available literature data and found to be in good agreement. The ⁵⁸Ni(n, p) ⁵⁸Co reaction as a function of neutron energy is also calculated theoretically using TALYS computer code version 1.2 and found to be higher than the experimental data.