95Tc and96Tc production by (γ, xn) reactions

The⁹⁹Tc (, 3n)⁹⁶Tc and⁹⁹Tc (, 4n)⁹⁵Tc reactions were studied by irradiation of target⁹⁹Tc with bremsstrahlung from the linear electron accelerator of Tohoku University, up to 50 MeV -energy. The resulting⁹⁶Tc (4.3 d) and⁹⁵Tc (20 h) activities were determined by -spectrometry. The -flux was monitored by the⁹⁹Tc (, )^99mTc reaction. Metallic copper and gold foils were used as additional flux monitors in front of and behind the samples. Their measured radioactivity was utilized for normalizing bremsstrahlung flux calculations, in order to determine reaction cross sections. Cross sections were also determined theoretically, performing calculations in the framework of a neutron cascade evaporation model. Above the (, 3n) and (, 4n) threshold energies the neutron emission channel was supposed to be the only open channel for deexcitation following photoabsorption. The preeguilibrium contribution was considered negligible. The experimental results obtained for the integrated cross section at 30 and 50 MeV fit reasonably well the calculated curves.     

Separation of rare earth elements from uranium by solvent extraction and ion exchange

The detection limit of⁹⁹Tc in (,) radio-activation analysis was determined in the presence of molybdenum and compared with that of⁹⁹Tc in pure materials in the previous paper. The isotopic ratio of molybdenum in a⁹⁹Mo–^99mTc generator column could be simultaneously determined by photon activation analysis.     

Study of CO oxidation on the (111) face of nickel during Ni?NiO phase transition

CO oxidation on the (111) face of Ni has been studied over a wide temperature range and reactant ratio in CO+O₂ reaction mixtures. A significant nonstationary increase in the reaction rate due to the formation of a two-dimensional surface oxide has been found. Subsequent formation of threedimensional NiO(111) phase sharply decreases the CO oxidation rate.

---

CO (111) Ni (CO+O₂). , . , NiO(111) CO.

     

The predictive accuracy for estimating infinite dilution activity coefficients by γ∞-based UNIFAC

The predictive accuracy for estimating infinite dilution activity coefficients by a modification of the UNIFAC method wherein the group interaction parameters were based on only data (referred to as -based UNIFAC) has been studied. Estimates and measured values were compared for six prototypical solutes in a series of homologous n-alkanes, l-alcohols and alkanenitrile solvents. Despite the fact that the interaction parameters were derived using only data, this approach still gave serious errors due to several inherent problems in the original UNIFAC model. Its performance is sometimes even poorer than that of the original UNIFAC method. For example for nitromethane in alcohols and p-dioxane in nitriles values predicted by the -based UNIFAC are essentially zero. The large errors for these systems are most likely due to inaccurate interaction parameters in the -based UNIFAC method.     

Integral cross section of the99Tc(γ,γ′)99mTc reaction at 4 MeV

^99mTc production was studied with the aid of photoexcitation by a 4 MeV endpoint energy bremsstrahlung from the LINAC of the Institute of Isotopes, Budapest. The intensity of the -flux was monitored by disc-shaped natural indium plates, placed in front of and behind the small cylindrical aluminium holders containing TcO₂ samples in a powder form. Isomeric activities were measured through the 140 keV -line by a Ge spectrometer. The integral cross section at 4 MeV was found to be 63.3±7.1 bMeV, which can be considered reasonable compared to the corresponding value of 55.3 bMeV established for the¹¹⁵In (,)^115mIn reaction. We also attempted the photoexcitation of^99mTc by irradiation with -rays from a 1.5×10¹⁵ Bq⁶⁰Co source, but no isomeric activity could be observed. This places the first activation level between 1.33 and 4 MeV.     

The role of induced secondary radiation in in situ sorption studies using β-, γ-emitting radionuclides

This article is focused on the effect of -induced radiation in in situ sorption measurements of⁶⁰Co (emitting -and -radiation). The results presented show that the intensity of solution background is primarily due to the -induced radiation (possibly caused by photoeffect and Compton-scattering) and does not change during cobalt accumulation. Experiments were carried out with a pure -emitting isotope (⁹⁹Tc) in order to elaborate a method for the separation of the intensities originating from -and -induced radiations. Various methods of evaluation of sorption measurements are discussed. The extension of the method to application of different radioactive nuclides is considered.     

Competitive hydrogenation of 2-methyl-3-butene-2-ol and 1-hexene on a platinum catalyst modified by amines

The effect of the amount of diethylamine and triethylamine on the degree of poisoning of a hydrogenation catalyst 10% Pt on silica gel was examined. The dependence of the selectivity of competitive catalytic hydrogenation of 2-methyl-3-butene-2-ol and 1-hexene in methanol and cyclohexane on the degree of poisoning was investigated.

---

(10% Pt ), 2--3--2- 1- .

     

Study of solid-phase reaction of RbNO3 with V2O5

Using DTA, TG and DTG methods, the reaction between RbNO₃ and V₂O₅ in the molar ratio 65 in air atmosphere was studied. The reaction proceeds stepwise. In individual steps of the reaction the formation of RbV₃O₈, RbVO₃ and Rb₃V₅O₁₄ was observed. Rubidium pentavanadate is thermally unstable. At 1000°, RbVO₃ and Rb₂V₄O₁₁ were identified as products of its thermal decomposition. Rubidium tetravanadate was also prepared by the isothermal reaction of RbNO₃ with V₂O₅ in the molar ratio 11.

---

Zusammenfassung Unter Anwendung der DTA-, TG- und DTG-Methoden wurde die Reaktion RbNO₃-V₂O₆ bei dem Molverhältnis von 65 in Luft untersucht. Die Reaktion verläuft stufenweise. Bei den einzelnen Stufen der Reaktion wurde die Bildung von RbV₃O₈, RbVO₃ und Rb₃V₅O₁₄ beobachtet. Rubidiumpentavanadat ist thermisch instabil. Bei 1000° wurden RbVO₃ und Rb₂V₄O₁₁ als Produkte seiner thermischen Zersetzung beobachtet. Rubidiumtetravanadat wurde auch durch die isotherme Reaktion von RbNO₃-V₂O₅ bei dem Molverhältnis von 11 hergestellt.

---

Résumé On a étudié par ATD, TG et TGD dans l'air, la réaction RbNO₃-V₂O₅ (rapport molaire 65). La réaction s'effectue par étapes, avec formation de RbV₃O₈, RbVO₃ et Rb₃V₅O₁₄. Le pentavanadate de rubidium est thermiquement instable. A 1000°, RbVO₃ et Rb₂V₄O₁₁ ont été identifiés comme produits de la décomposition thermique. Le tétravanadate de rubidium a également été préparé par voie isotherme en faisant réagir RbNO₃-V₂O₅ (rapport molaire 11).

---

, , RbNO₃-V₂O₅ 6 5. . RbV₃O₈, RbVO₃ Rb₃V₅O₁₄. 1000° RbVO₃ Rb₂V₄O₁₁, . RbVO₃-V₂O₅ 11.

     

α,β-Butenolides

,-Dibromo--('-carbethoxyacetony)-^,-butenolide (I) reacts with amines in diethyl ether solution to give -bromo-amino--('-carbethoxyacetony)-^,-butenolides. Compounds n are converted to -bromo-amino--('-carbethoxyacetony)-^,-butenolides on reaction with amines. The corresponding arylhydrazones (VI and VII) are obtained by the reaction of I and II with p-nitro- and 2,4-dinitrophenylhydrazines. Compound I reacts with phenylhydrazine to give furopyridazine VIII.See [1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–871, July, 1972.     

Matrix effects on Kβ/Kα X-ray intensity ratios of technetium-molybdenum systems

The K/K X-ray intensity ratios of^99mTc produced in molybdenum compounds by the /n,/^– processes were found different from those of chemically separated^99mTc. Chemical states of molybdenum seem to have an effect on the X-ray ratio K ₂ /K. The X-ray intensity ratios were investigated with other technetium nuclides^95mTc and^97mTc. The Mo X-rays and Tc X-rays emitted from these nuclides in molybdenum matrix showed smaller values of K ₁ /K and K ₂ /K than those for chemically separated ones. Influence of electronic structure on the ratios by surrounding matrix was discussed.     

Characterization and use of a gamma radiation TLC scanner for radiochemical purity measurements of radiopharmaceutical kit preparations of99mTc(dmpe)2Cl 2 +

A simple, low cost TLC scanner system for the characterization of -emitting radiopharmaceuticals is described. The TLC scanner has a linear response range of 0.074 Mbq up to 2.94 Mbq. The accuracy and reproducibility of measurement is better than ±5% (relative). The utility of this TLC scanner system is demonstrated by application to the radioanalytical evaluation of^99mTc(dmpe)₂Cl ₂ ⁺ preparations. A comparison with HPLC radioanalytical separations is made.     

Adsorption behavior of polymers having phosphoric acid group on γ-Fe2O3 and magnetic characteristics in magnetic coatings

Polymers having phosphoric acid groups were prepared as a model binder for magnetic coatings, and the correlation among the adsorption behavior of the polymers onto-Fe₂O₃ particles and the dispersibility, the orientation, and the packing density of-Fe₂O₃ particles in the magnetic coatings was investigated.PMMA homopolymer molecules hardly adsorbed on-Fe₂O₃, and the interfacial tension at a water/polymer solution (toluene) interface ( _W/T) was scarcely changed compared with a water/toluene interface. Increasing with the content of polymeric phosphoric acid group, the adsorbance of polymer increased and the interfacial tension ( _W/T) decreased. When the content of polymeric phosphoric acid groups was over 0.4 mol%, the adsorbance of polymer and interfacial tension ( _W/T ) remained constant. When these polymers were used as a binder for magnetic tapes, the dispersibility of-Fe₂O₃ in the magnetic coatings was improved, increasing with the content of polymeric phosphoric acid group; however, when the content of phosphoric acid group was over 0.2 mol%, its dispersibility decreased abruptly.Studies on Recording Magnetic Materials and Magnetic Composite. XVIII.     

Mass spectrometric study of monoalkyl-substituted thiacyclanes

Monosubstituted - and -alkylthiophans and -, -, and -alkylthiacyclohexanes were subjected to a comparative mass spectrometric study. The stability of the M⁺ ion increases on passing from - to -alkylthiophans and from - to - and -alkylthiacyclohexanes. In the case of -alkylthiophans and - and -alkylthia-cyclohexanes the principal process is associated with ejection of the substituent as a whole, whereas a portion of the alkyl substituent, with retention of one CH₂ group in the composition of the charged fragment, is eliminated from the molecular ions of -alkylthiophans and -alkylthiacyclohexanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 176–181, February, 1978.     

Solubility Study of Nimodipine Inclusion Complexation with α- and β-Cyclodextrin and some Substituted Cyclodextrins

The solubility of nimodipine was measured in aqueous solutions of the following cyclodextrins: -cyclodextrin (-CD), hydroxypropyl--CD (HP--CD), -cyclodextrin (-CD), random substituted methyl--CD (M--CD), three hydroxypropyl--CDs (HP--CD) with mutually different average degree of substitution, and hydroxypropyl--cyclodextrin (HP--CD). From the determined linear solubility diagrams the values of the binding constant K₁₁ of the inclusion complexes of nimodipine with the respective CDs were evaluated. The -CDs efficiently solubilized sparingly soluble nimodipine, the highest value of K₁₁ was found for M--CD (1680 M^-1), followed by -CD (550 M^-1) and HP--CDs, where the higher degree of substitution lowered K₁₁. Only slight solubilization of nimodipine was observed in the solutions of the -CDs and HP--CD.     

Fast non-destructive determination of silicon in coal by means of /n,n′ γ/ and /n, γ/ processes

The possibilities were evaluated of nondestructive determination of silicon content in large-scale samples of coal /about 20–50 kg/, based on the spectrometry of prompt -radiation from processes /n, n /, E=1779 keV and /n, /, E=3539 keV and 4935 keV. The neutron sources were either²⁴¹Am–Be or²⁵²Cf located additionally in D₂O moderator. A Ge/Li/ detector was used for -radiation detection. In exposure times of up to 2 h, the detection limits of 1.3% and 0.9% and accuracies of silicon determination of 0.66% and 0.40% have been achieved in case of /n, / and /n, n / processes, respectively.     

Aqueous solubilities and octanol-water partition coefficients of binary liquid mixtures of organic compounds at 25°C

From thermodynamics and certain assumptions it is shown that, under the usual experimental conditions, the octanol-water partition coefficient (K_o/w) of a given organic liquid should be the same whether the substance is partitioned neat or as part of a mixture. Measurements of several mixtures of n-propylbenzene (log K_o/w=3.71±0.04)+ethylbenzene (log K_o/w=3.16±0.01) clearly confirm this. It is also shown that the aqueous solubility (S_w) of a neat organic liquid can be related to its aqueous solubility (S _w ), when it is present at volume fraction in an organic liquid mixture, by S _w =S_w, where is its activity coefficient in the organic mixture. The measured S _w values for n-propylbenzene + ethylbenzene (1), n-hexane + nitrobenzene (>1) and di-isopropyl ether + chloroform (<1) are found to be in good agreement with the predicted values (average differences of, respectively, <2%, 8% and 6%). In general, the bounds on S _w are expected to be 0w w.     

Synthesis of biphenyl derivatives by coupling reaction of halobenzenes with organonickel (0) complexes

A study of the coupling reaction of substituted halobenzenes with a zero valent pyridine-nickel complex as catalyst, leading to biphenyl derivatives, has been made. Electron-releasing groups as substituents favor the formation of coupling products in low yields, while electron-withdrawing groups as substituents suppress the formation of dimers.

---

, , . , .

     

Microcalorimetric Evaluation of Precipitation in Cu–2Be–0.2Mg

Beryllium precipitation from the Cu-rich matrix in a Cu–2 mass% Be–0.2 mass% Mg alloy homogenized and quenched from 1073 K was studied by differential scanning calorimetry (DSC). The DSC traces showed two main exothermic effects, A and B, each comprising two subeffects: A₁ and A₂ , and B₁ and B₂ respectively. Effects A₁ and A₂ correspond to the precipitation of GP zones and subsequent overlapping and independent precipitation of the phase. Only at very low heating rates can be inherited from GP zones. Effects B₁ and B₂ correspond to heat evolved during transitions to the states with and phases, respectively. Heat effect A can be quantitatively described in terms of solid solubilities before and after precipitation, and of the precipitation heats of the phases involved. The heat content of the combined GP zone/ phase precipitation effect was proportional to the number of beryllium atoms precipitated, yielding an average value of 21 kJ mol^–1 beryllium for beryllium precipitation. It was shown that the phase arises from the combined transition from states with GP zones and phases, whereas arises from the transition of states with and phases. The apparent activation energies associated with GP zones and , and phases are 1.16±0.08, 1.18±0.07, 1.37±0.08 and 1.74±0.09 eV, respectively. These values are discussed in terms of the mobility of dissolved atoms related to the concentrations of excess vacancies and solute-vacancy complexes, and the direction of plate-like precipitate growth (either normal or perpendicular to the plate). It is inferred that the main roles of magnesium are to decrease the amount and rate of GP formation, to enhance the volume fraction of and to suppress the discontinuous precipitation of .This revised version was published online in November 2005 with corrections to the Cover Date.     

Effect of ageing atmospheres on the changes in surface free energies of oxygen plasma-treated polyethylene films

The changes in the surface properties of oxygen plasma-treated polyethylene films during ageing in various atmospheres (water, dry nitrogen gas, and hexane) were studied from the viewpoint of the interaction of the surface functional groups formed on the films and the ageing media. The XPS (x-ray photoelectron spectroscopy) and the SSIMS (static secondary ion mass spectrometry) spectra indicated the formation of polar groups containing oxygen such as C=O on the film surface. The changes in the critical surface tension (_C) of the film with ageing time were largely affected by the ageing atmospheres: the _C value of the film aged in water increased, and those of the films aged in nitrogen gas and hexane decreased with an increase in ageing time. These different tendencies among the ageing media could be understood reasonably with examining the surface free energy ratios (the total energy, _S ^tot , the dispersion force component, _S ^d / _S ^tot , the polar component, _S ^p / _S ^tot , the hydrogen bonding component, _S ^h / _S ^tot ) of the films. The ageing in water of which _L is large gave the films with higher _S ^p / _S ^tot values, suggeting that the overturn and/or the orientation of the polar groups toward the water phase occurred so as to minimize the discrepancy of the surface free energy between the polymer surface and water. On the other hand, the ageing in nitrogen gas and hexane media of which _L are small gave the films with lower _S ^p / _S ^tot and _S ^h / _S ^tot values, suggesting the overturn and/or the orientation of the polar groups into the bulk polymer.     

Kinetics of oxidation of vanadium(III) by hydroxylamine in acid medium

The kinetics of oxidation of vanadium(III) by hydroxylamine have been investigated at high acidities in the temperature range 25–30 °C. Rates decreased with increasing acidity of the medium. Both NH₂OH and NH₃OH⁺ are capable of oxidizing V(III) in parallel reactions, the order being unity each in oxidant and reductant.

---

(III) 25–30 °C. . NH₂OH NH₃OH⁺ V(III) , , .