Infrared spectral analysis during the thermal decomposition of pure and irradiated crystalline NH4ClO4

Variable temperature /303–553 K/ IR spectroscopic studies are made during thermal decomposition of pure and -treated ammonium perchlorate /AP/. Decomposition is enhanced by radiation or in the presence of an additive /Gd₂O₃/. Intensity of the stretching /1100 cm^–1/ and bending /625 cm^–1/ frequencies of ClO ₄ ^– decrease on heating the KBr matrix even below 360 K. Above this temperature, a broad band develops over 480–510 cm^–1 in the pure and -treated AP which is attributed to ClO ₃ ^– /₄/.     

A new improved expression for gamma-ray detection efficiency of Ge(Li) detectors

In the present paper, a new improved expression for -ray detection efficiency of Ge(Li) detectors, ⁰ , is given. It is represented as a continuous function of x (viz. E ^–1) with a maximum and decreases very rapidly to a small positive value as -ray energy, E, drops to 40 keV or lower, but slowly as E rises to 1.7 MeV or higher. Since it can well represent the whole physical process of the -ray detection, this expression may be one of the simplest and most precise representations, for ⁰ at the present time.     

New Molybdenum(V) Complexes Prepared by the Oxidation of Dinuclear Quadruply-Bonded Molybdenum(II) Monothiocarboxylates

Oxidation of molybdenum(II) thiopivalate and thiobenzoate in the presence of -picoline or pyridine results in the formation of dinuclear molybdenum(V) complexes of the general formulae [Mo₂O₂(-O)₂(-SO₄)L₄] with L = -picoline or pyridine and [Mo₂O₂(-O)(-S)(-SO₄)L₄] with L = -picoline. As determined by X-ray structure analysis, two complexes with -picoline differ in their bridging cores: In one complex, two Mo atoms are doubly bridged through two oxygen atoms; in the other, one Mo atom is doubly bridged through oxygen and sulfur atoms. However, they both crystallize together. The product is solvated with -picoline and water molecules. Molybdenum atoms exhibit distorted octahedral coordinations. The same complexes were prepared also through direct reactions of [Mo₂O₃(O₂CCH₃)₄] with thiopivalic and thiobenzoic acid in the presence of -picoline or pyridine. The appearance of the oxo-oxygens and sulfido-sulfur as well as sulfato ligand is explained by the molybdenum-catalyzed oxidation of thiocarboxylates.     

Further study on parametric standardization in reactor NAA

A post-K_o study of parametric reactor NAA is described including the determination and applications of working K_oS for non-1/V reactions¹⁵¹Eu(n,)¹⁵²Eu and¹⁷⁶Lu(n,)¹⁷⁷Lu; parametric corrections for²³⁵U fission, threshold reaction and -spectral interferences; and parametric normalizations for different counting geometries. The analytical significance, the principles, the experimental confirmations, and the application examples of these methods are briefly introduced.     

A new detection method of99Tc by nuclear excitation

A new nuclear excitation process,⁹⁹Tc (, )^99mTc reaction, was applied for the first time to radioactivation analysis of technetium. Bremsstrahlung irradiation of⁹⁹Tc samples gave the reaction product^99mTc which emits -ray measurable with ease by a semiconductor detector. The production rate of^99mTc per g⁹⁹Tc was linearly correlated with the flux of bremsstrahlung. The detection limit of⁹⁹Tc was estimated to be nanogram order (0.63 Bq⁹⁹Tc) under the optimum irradiation condition. Possible interference by¹⁰⁰Ru(, p)^99mTc reaction was also studied, which could be discriminated from the (, ) reaction by simultaneously occurring⁹⁸Ru (, p)⁹⁷Ru reaction.     

Gamma radiolysis of Methyl Red solution and reaction induced by γ-irradiated NaCl in Methyl Red

The -radiolysis of Methyl Red solution in HCl medium at pH=2 has been studied along with energy transfer reaction brought about byF and hole centers of -irradiated NaCl. The G-values for degradation of the azo dye indicator by radiolysis and -irradiated salt were determined as 9·10^–1 and 4.8·10^–3, respectively. The kinetic rate constants (k) of degradation are evaluated as 2·10^–5 rad^–1 in the case of direct radiolysis, while for the irradiated salt it is 2·10^–7 rad^–1. The extent of degradation by direct -radiolysis is 100–200 times greater as compared to that by the -irradiated salt. The same mechanism is proposed for radiolysis as well as the reaction induced by -irradiated sodium chloride.     

Preparation and Characterization of Thin Optically Transparent Alumina and Ce-doped Alumina

Transparent and porous boehmite, -Al₂O₃ (500°C) and -Al₂O₃ (900° and 1000°C) thin sheets (50–100 m) have been prepared from boehmite sols. -Al₂O₃ shows about 48% porosity and 292 m²/g surface area. On transformation from -Al₂O₃ (500°C) to -Al₂O₃ (900°C), the porosity still remains high, i.e. 45%; however, the surface area becomes 138 m²/g. The porosity and surface area of -Al₂O₃ become about 41% and 97 m²/g respectively on further heating to 1000°C. A gradual increase of average pore radius during this thermal treatment suggests that coarsening of the pore occurred during the densification process. Both -Al₂O₃ and -Al₂O₃ show high degree of transmission from UV to NIR wavelength region. Cerium exists in +4 oxidation state in the boehmite as well as in the - and -Al₂O₃. The ultraviolet absorption edge of the alumina was tailored by varying the concentration of cerium.     

/α, γ/ reaction on197Au

The excitation funcntion has been measured for the /, / reaction on¹⁹⁷Au. The nuclide produced was determination by gamma spectrometry with a Ge intrinsic detector. Irradiation was carried out in the Karlsruhe Isochronous Cyclotron with -particles of energies up to 40 MeV.     

Fluorescent Molecular Sensing System Based on Tri-Pyrenes-Labeled γ-Cyclodextrin at the Hetero Rim

Fluorescent active host labeled at the upper and lower rims of -cyclodextrin, namely, mono-3^A-deoxy-3^A-pyrenebutylamido-6^X,Y-O-bis-pyrenebutylate-mono-altro--cyclodextrin (-3) has been synthesized as a chemosensor for steroidal guests using fluorescence spectra change upon a guest addition. The -3 shows monomer and excimer fluorescence, which results in an increase of the intensity of monomer and decrease of excimer fluorescence with a host–guest binding in the cyclodextrin cavity. The extent of monomer and excimer fluorescence variations of -3 was used as an indication for the sensing ability for the guests examined. The guest-induced fluorescence changes were measured for 10^–7 M solutions of -3. The sensing parameters (I_ex/I⁰_ex and I_mon/I⁰_mono) were used to describe the sensing ability of -3. The values of I_ex/I⁰_ex describe that -3 shows less selectivity for guests than that of mono-3^A-deoxy-3^A-pyrenebutylamido-6^X-O-mono-pyrenebutylate-mono-altro--cyclodextrin (-2), and the values of I_mon/I⁰_mono show that -3 shows higher sensitivity and selectivity than that of -2.     

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.     

Environmental importance of the107Ag(n,γ)108Agm reaction in nuclear power reactors,and new 327-1327-1327-1and Iγ measurements

127-year¹⁰⁸Ag^m is an (n,) activation product of¹⁰⁷Ag and is produced in nuclear power reactors. Due to the wide range of reported values for the o ⁰ cross section of the¹⁰⁷Ag(n,)¹⁰⁸Ag^m reaction new measurements were made—resulting in a o ⁰ value of 0.477±0.033 barn, and an I value of 0.80±0.15 barn. The environmental importance of the¹¹⁰Ag^m and¹⁰⁸Ag^m radionuclides is discussed.     

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.     

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.     

Activation cross sections for some isotopes of Zr,Mo, Br,Ta and Ce at 14.7 MeV neutrons

The (n,p), (n, ), (n, 2n) and (n, ) reaction cross sections on^90,92Zr,^92,97,98,100Mo,^78,81Br,¹⁸¹Ta,¹⁴⁰Ce target nuclei have been measured forE _n=14.73±0.05 MeV neutrons using the activation technique. The induced -ray activities of the irradiated samples and their monitor foils were measured by using HPGe detector. The cross sections are compared with the existing results. The experimental uncertainties are between 3% and 10% in most cases.     

Adsorption Isotherm Accounting for the Electrode Elasticity: Special Solutions

The single-phase adsorption on a solid electrode out of a dilute solution is investigated. As a continuation of the previous paper, on the basis of the complete electrocapillarity equation, an adsorption isotherm equation is derived and supplemented by equations of compatibility of the physical quantities. The equations contain a new parameter, , which is a derivative of the dimensionless surface adsorbate concentration by the relative variation of the electrode surface area. Their solution is obtained in relation to the dimensionless charge density of the electrode surface q for the case of = (). As a result of employing a linear model for q by , the problem of determination of the unknown model functions is reduced to common differential equations that use the capacitance or estance curves as the boundary conditions. In the first case, we suggest to calculate the unknown integration parameter by the method of mathematical optimization, employing coulometric data.     

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.     

NAA with gamma-line related (k o) and isotope related (k i) analytical factors

Thek _o-standardization method is based on analytical constants, which are -line related and the results are calculated from the peak areas of the -ray spectrum. Consequently, prerequisites of this method are the correct identification of the -lines and the avoidance of unresolved peak interferences. Because these problems are already solved with nuclide identification programs, a new variant of thek ^o-method was developed, using the activities of the nuclides instead of the peak areas. We introduced isotope related factors,k _i, calculated fromk _o-factors. The procedure is described and results are compared with those obtained by the -line based method.     

Role of multiple bonds of tetracoordinated phosphorus atom in the magnetic shielding of its nucleus

On the basis of a previously proposed approach to investigation of the nature of the chemical shift ³¹P, it has been shown that the dependence of shielding of the ³¹P nucleus on the multiplicity of one of the bonds (PM) of the phosphorus atom in the molecule is not monotonic over the entire interval of variation of the corresponding parameter _PM. When _PM is smaller than a certain value ₀, which is determined by the difference between interactions of the P atom with the atom in question (M) and other substituents, the dependence of ³¹P nuclear shielding on _PM should be antibatic, and when _PM > ₀ symbatic.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 4, pp. 439–446, July– August, 1989.     

γ-Cyclodextrin-enhanced dimerization of viologen radicals

The effects of cyclodextrins (CDs) on the monomer-dimer equilibria of 1,1-dialkylviologen radical cations (Cn Cn V^.+ :n = 1–5) and one-electron reduced 1,1-bis(3-sulfopropyl)viologen (SPV) were investigated spectroelectrochemically. The dimerization is enhanced upon addition of-CD, while the addition of-CD and-CD suppresses the dimerization. This is attributed to the stabilization of dimers by the inclusion of the dimer in the cavity of-CD From the dependence of the apparent dimerization constants (K _D ) on the concentration of-CD the association constants of the monomer (K _C1) and dimer (K _C2) with--CD were determined. TheK _C1 value increases slightly, from 5 M^–1 forn = 1 to 35 M^–1 forn = 5, as the length of the alkyl substituents of viologen increases. TheK _C2 value depends strongly on the alkyl substituents giving the smallest value of 85 M^–1 for (SPV^.–)₂ and the largest one of 3500 M^–1 for (C₄C₄V^.+)₂. These results, together with the difference in UV-vis absorption spectra obtained in the absence and in the presence of-CD, suggest that the alkyl substituents and part of the bipyridine ring of viologen radicals are included in the-CD cavity forming dimers in which the bipyridine rings are stacked at an oblique angle.     

Molekülbewegung in Polymeren

Zusammenfassung Die 2g1-Kinke wird als Baufehler mit 4 möglichen Lagen im idealisierten PÄ-Kristall elastizitätstheoretisch durch je einen Kräftedipol beschrieben. Die Berechnung des Relaxationsbetrags für den -Prozeß in PÄ — Kinkschritt (_II) und Kinksprung (_II) — ergibt mit h·c=0,0006 Übereinstimmung mit der in (7) verwendeten paraelastischen Abgleitvorstellung und mit dem Experiment. Mittlere 2g1-Kinkblockgrößeh und Defektanteil der thermischen Ausdehnung werden unter der Nebenbedingung konstanter 2g1-Kinkkonzentrationc diskutiert.

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Summary The 2g1-Kink is considered as an elastic dipole in the idealized PE-crystal, with 4 possible positions, that is 4 dipol-tensors. The calculated relaxation strength for the -process in PE — kinkstep (_II) and kinkjump (_II) — agrees with the results obtained by considering a simple shear displacement (7) and with experiment, assuming h. The mean number h of 2g1-kinks in a bloc and the thermal expansion due to these kink defects are discussed under the additional condition that 2g1-kinkconcentrationc is constant.

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Mit 2 Abbildungen in 3 Einzeldarstellungen und 5 Tabellen

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Herrn Dr.H. Oberst zum 65. Geburtstag gewidmet.