Binuclear Osmium μ-Oxocarboxylate Complexes [Os2(μ-O)(μ-O2CR)2Cl4L2] (R = CH3, CCl3; L = PPh3, AsPh3) and Their Electrochemical Behavior in Dichloromethane

Cyclic voltammetry and galvanostatic coulometry techniques were used to determine how the redox properties of osmium binuclear -oxocarboxylates [Os₂ ^IV(-O)(-O₂CR)₂Cl₄L₂] (R = CH₃, CCl₃; L = PPh₃ and R = CH₃; L = AsPh₃) are influenced by the nature of the bridging carboxylate ligand RCOO^– and ligand L. It was shown that all compounds in solution of dichloromethane undergo two single-electron reduction processes. The data obtained were compared with the DFT calculations of the electronic structure of the model complexes [Os₂ ^IV(-O)(-O₂CR)₂Cl₄L₂] (R = CH₃, CCl₃; L = PH₃ and R = CH₃; L = AsH₃).     

The dependence of build-up233U,232U,233Pa and fission products from ThO2 irradiated in HFETR on integral thermal neutron fluxes and neutron spectra

In this paper the dependence of build-up²³³U,²³²U,²³³Pa and fission products from ThO₂ irradiated in HFETR on integral thermal neutron fluxes and neutron spectra have been investigated. The yields of all above nuclides in ThO₂ increase with the increase of integral thermal neutron fluxes at different neutron spectra. The values of²³³U/²³²Th increase with the increases of _th and decreases with the increase of fast/thermal neutron ratios (_f/_th). The values of²³²U/²³³U increase with the increase of both _th and _f/_th ratio. The amount of fission products relative to original irradiated thorium decreases with the increase of _f/_th ratios. These results could be used to evaluate the behaviour of thorium-based nuclear fuel in reactor.     

Arenobufagin and gamabufotalin from the venom of the Central Asian green toadBufo viridis. Introduction,structural—functional features

Two bufodienolides have been isolated in the individual form from the Central Asian green toadBufo viridis for the first time. It has been established by₁H NMR, mass spectrometry, and x-ray structural analysis that these compounds are gamabufotalin (3, 11, 14-trihydroxy-5, 14ß-bufa-20,22-dienolide) and a crystalline modification of arenobufagin (3, 11, 14-trihydroxy-12-oxo-5, 14-bufa-20,22-dienolide). The biological activity of Bakagin — the total bufadienolides of the venom ofB. viridis, consisting predominantly of the compounds named — has been studied. The promising nature of a further study of Bakagin as a cardiotonic drug has been shown.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 260–268, March–April, 1995. Original article submitted October 10, 1994.     

Production of anomalous polymer microspheres having uneven surfaces by “stepwise” heterocoagulation technique

Anomalous polymer microspheres having uneven surfaces were produced by stepwise heterocoagulation technique of small polymer particles (SPs) onto large polymer particles (LPs).SPs andLPs have surface charges opposite to each other in the emulsion states.SPs were produced by emulsion copolymerization of styrene and methacryloyloxyethyltrimethylammonium chloride, andLPs by emulsion terpolymerization of styrene, butyl acrylate and methacrylic acid, with nonionic emulsifier being used in both cases. Maximum covering ofLP bySPs was obtained under the conditions that both emulsions were blended without the coagulation at pH 3 at room temperature and then left stand to coagulate with each other at 70 °C for 4 h at pH 9.Part CXI of the series Studies on Suspension and Emulsion.     

The biological half-life of137Cs in snails

The biological half-life of¹³⁷Cs in snails Helix pomatia after a single administration of contaminated diet has been investigated. The calculation was based on the retention of¹³⁷Cs in snails in vivo. It was found that loss of cesium from snails can be explained by a two-exponential retention curve leading to biological loss constants _{B 1}=0.27 d^–1 and _{B 2}=0.024 d^–1, which correspond to biological half-lives of T_{B 1}=2.5 d and T_{B 2}=28.5 d respectively. The equation describing the retention of¹³⁷Cs in snails is also presented.     

Structure of casein micelles I. Small angle neutron scattering and light scattering fromβ- andχ-casein

Casein is the main protein component of milk and is of remarkable colloidal stability. Under the influence of milk clotting enzymes casein shows the striking behaviour of coagulation. This clotting process has already been studied by other groups, neglecting the fact that casein is not a homogeneous protein. The purpose of the present study is focused, in this first stage, on the determination of the structure of the various casein components. In cooperation with other laboratories we have been able to obtain the well separated individual proteins. Studies have been performed so far with- and-casein. For detailed structural information we carried out small angle neutron scattering and combined static and dynamic light scattering measurements and determined the molecular weight,M _w, the radius of gyration, S ² the hydrodynamic radius,R _H, the-value and the particle scattering factor, P_z(q). The two caseins show a strikingly different behaviour. For the-casein we found a star-like structure, i. e. an aggregation pattern that is expected for a common micelle. The micelle consists of about 38 monomer chains. The aggregates of-casein appear to be composed of star-like submicelles, where each submicelle contains nine-casein chains and the total degree of aggregation is about 140.     

Thek 0 calibration of the IRI system for INAA of samples in the kg range

The feasibility of the INAA of samples in the kg range has been demonstrated in 1994 byOverwater et al. In his studies, however, he demonstrated only the agreement between the corrected -ray spectrum of large samples and that of small samples of the same material. In this paper, thek ₀-calibration of the IRI facilities for large samples is described, and some ofOverwater's results for homogeneous materials are presented again, this time in tems of (trace) element concentrations. It is concluded that large sample INAA can be as accurate as ordinary INAA.     

Bestimmung kleiner Gehalte an Zink, Nickel nnd Eisen in Titan-, Zirkonium- und Thoriumdioxid, sowie an Uran in Thoriumdioxid mittels R?ntgenfluorescenzanalyse

Zusammenfassung Die Untersuchungen zur Bestimmung kleiner Gehalte an Zink, Nickel und Eisen in den Dioxiden von Titan, Zirkonium und Thorium mittels Röntgenfluorescenzanalyse haben gezeigt, daß die Eichkurven für Zn, Ni und Fe in TiO₂ in dem untersuchten Bereich (bis 0,1%) geradlinig verlaufen. Beim ZrO₂ wurde Geradinigkeit für Zn und Fe bis etwa 0,4% für Ni nur bis etwa 0,1% gefunden. Beim ThO₂ war die Nettoimpulszahl D der Konzentration c proportional für Zn, Fe und U bis zur untersuchten Konzentration von 1,288%, für Ni nur bis etwa 0,4%. Die Nachweisgrenzen der Elemente für eine Zählzeit von 5 min und eine statistische Sicherheit von 99,7% ergaben sich wie folgt: TiO₂ Zn 0,001, Ni 0,001, Fe 0,003; ZrO₂ Zn 0,002, Ni 0,002, Fe 0,007; ThO₂ Zn 0,006, Ni 0,005, Fe 0,015, U 0,02 Gew.-%.

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Summary Investigations on the determination of low concentrations of zinc nickel and iron in TiO₂, ZrO₂, and ThO₂ and of uranium in ThO₂ by means of X-ray fluorescence analysis have shown that the calibration curves are linear for Zn, Ni, and Fe in TiO₂ in the investigated range of 0.1%, for Zn and Fe in ZrO₂ of 0.4%, for Ni in ZrO₂ of 0.1%, for Zn, Fe, and U in ThO₂ in the investigated range of 1.288% and for Ni in ThO₂ of 0.4%. The calculated limits of detections for a counting time of 5 min and 99.7% confidence are: TiO₂: Zn 0.001, Ni 0.001, Fe 0.003; ZrO₂: Zn 0.002, M 0.002, Fe 0.007; ThO₂: Zn 0.006, Ni 0.005, Fe 0.015, U 0.02 w.-%.

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Herrn Prof. Dr. F. Strassmann zum 65. Geburtstag gewidmet.

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Herrn Prof. Dr. Ing. F. Strassmann, dem Bundesministerium für Wissenschaftliche Forschung und der Deutschen Forschungsgemeinschaft danken wir für die Überlassung von Instituts- bzw. Forschungsmitteln.     

Phase behavior and dynamic properties in mixed systems of anionic and cationic surfactants: lithium perfluorooctanesulfonate/diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) and lithium dodecyl sulfate/DEFUMAC aqueous mixtures

Two ternary phase diagrams of the cationic perfluorosurfactant diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) with an anionic perfluorosurfactant lithium perfluorooctanesulfonate (LiFOS) and an anionic hydrocarbon surfactant lithium dodecyl sulfate (LiDS) have been established at 25°C. The total surfactant concentration was less than 20wt%. In a wide mixing region of the LiFOS/DEFUMAC system, a lamellar-type phase,P , was identified by its texture under a polarization microscope and by its x-ray diffraction pattern. Dispersed fragments ofP -phase are present in the dilute solutions in which one surfactant was in excess. The anisotropy of electrical conductivity, flow birefringence, dynamic light scattering, and electric briefringence demonstrate that theP fragments are disk-like with a radius of 0.7 m. The disk-likeP particles are transformed by shear into a spherical aggregate ofL above a critical shear gradient. LiDS/DEFUMAC mixed solution forms dispersed and precipitatedL in the dominant region. Radius and micropolarity of the dispersedL aggregates are decreased as the ratio of LiDS:DEFUMAC approaches 1:1. On the basis of x-ray diffraction measurement the structure of precipitatedL -phase seems to consist of monolayers.     

The structures of macrocyclic heterocyclophane inclusion complexes

Crystal and molecular structures of (1:1) molecular complexes of N,N,N,N-tetramethyl-2, 11, 20, 29-tetraaza [3.3.3.3] paracyclophane (1) with CHCl₃, CH₂Cl₂, CH₃CN and CO₂ are reported. The macrocycle has square-box structure, giving hydrophobic cavity surrounded by four benzene rings. The guest molecules are included in the cavity. The uncomplexed1 was found to have a rectangular form, indicating large conformational flexibility of1. In solution,1 is achiral because rapid RS interconversion, but in solid, the macrocyclic conformation is frozen as R-conformer or S-conformer. The macrocycles with the same chirality are stacked alongb-axis to form chiral molecular columns, R-colums or S-columns. Complexes of1 crystallize differently depending on the guest molecules. R-columns (S-columns) packed alonga-axis produce R-layers (S-layers), which are further packed alongc-axis using R-layer to R-layer contact (RR) or SS and RS or SR. The crystals of1·CHCl₃ are formulated as--RRR--=[R]_n (Type I, chiral) and those of1·CH₃CN or1·CO₂ and1·CH₂Cl₂ are represented by [RS]_n (Type IIA, racemic) and [RRSS]_n (Type IIB, racemic), respectively.     

Physicochemical characterization of boro- and gallo-silicate isomorphs ofβ-zeolite

The crystalline isomorphs of-zeolite containing boron or gallium in the framework positions have been synthesized and the products characterized by comparing them with Al- zeolite. Evidence for the presence of B or Ga in the zeolite lattice framework has been confirmed by spectroscopic (XRD, IR and²⁹Si,²⁷Al and¹¹B MASNMR), DTA/TG, ion exchange, sorption and catalytic activity results. Chemical analysis and NMR confirm the absence of any significant amount of Al in the zeolite (SiO₂/Al₂O₃=2000). The XRD pattern of the as-synthesized B- and Ga- compounds matched well with that of Al- zeolite. Lattice B and Ga leads to a change in the X-rayd values. Framework and bridging hydroxyl stretching IR bands of-zeolite are shifted due to incorporation of gallium and boron into the zeolitic framework. MASNMR spectra of¹¹B and²⁹Si also suggest the presence of tetrahedrally coordinated B(III) or Ga(III) ions in the-zeolite framework. B and Ga-zeolites exhibit significant ion exchange capacity and catalytic activity in them-xylene isomerization reaction. The shifts in the IR bands towards higher frequency in B- and lower frequency in Ga-, the observed ion exchange capacities and catalytic properties, indicate the presence of B³⁺ or Ga³⁺ ions in the framework of-zeolite.     

Entropy in dissimilarity and chirality measures

Within the prospect of quantifying the geometrical dissimilarity of molecular models on the basis of a thermodynamical formalism, the algebra of stereogenic pairing equilibria is reviewed and applied to molecular geometry: developing Rassat's proposition, an interaction energy of two figures F and F is taken as proportional tod _H ^Emphasis>/2 (F, F), whered _H denotes the Hausdorff distance. IfG is a group of rotations in E _n the geometrical version of the general equation (E) of the chemical algebra defines a distance extensionD _p(F,F) ofd _H(F,F), which is independent of the orientations of F and F, and where the coefficientp is interpreted as the reciprocal of a temperature-like parameter:p 1/T. At K (p = ), no formal entropy contributes to the definition of the uniform distanceD . At K (p = 0), the discrimination between homo- and hetero-pairing of figures by the harmonic distance Do is averaged over orientation states. Temperature-dependent chirality measuresc _p are derived fromD _p, andc is analogous to Mislow's chirality measure. If T and oT are normalized enantiomorphic triangles with coincident centroids inE ₂,c _p(T) =D _p (T, T) is calculated forp = 0 andp = , and discussed for 0 <p < . Finally, the Hausdorff interaction model is putatively related to energy profiles versus dihedral angle inmeso- anddl-molecules.     

Simple statistical mechanics of electrolytes with a concentration dependent dielectric constant. Part 1. The pressure equation

We have used an approximation of the Adelman's theory of solutions to take into account the non-pairwise additive effects on the interaction potentials for a real electrolyte solution. As a result, a solute concentration dependent dielectric constant appears. The comparison with experimental data is done by means of the pressure equation. The influence of on solution properties is analyzed in two molality ranges using as a reference simplified models but with the dielectric constant of the pure solvent instead of .     

Phenazine, 3. Mitt.: N-(o-Aminophenyl)-benzo[a]phenazin-5-amin,das vermeintliche “Dihydronaphthodiphenazin”Kehrmanns,und seine Derivate

The dihydronaphthodiphenazine ofKehrmann, which is according toBadger andPettit reported to be 14-o-aminophenyl-13,14-dihydro-5,8,13,14-tetraaza-6,7-benzopentaphene, is N-(o-aminophenyl)-benzo[a]phenazin-5-amine. This was proved by chemical and spectroscopic investigations. The structures of the derivatives prepared byBadger andPettit are also corrected and the acetylation processes are cleared up.     

The synthesis and structure of the [2.2]paracyclophane cluster Ru6C(CO)13(μ 3-η 2:η 2:η 2-C16H16)(PPh3) and a study of the 1H-n.m.r. spectra of [2.2]paracyclophane and benzene clusters

Summary The [2.2]paracyclophane cluster, Ru₆C(CO)₁₄( ₃- ^{2 2 2}-C₁₆H₁₆) (1), undergoes reaction with Me₃NO and triphenylphosphine to yield Ru₆C(CO)₁₃( ₃- ^{2 2 2}-C₁₆H₁₆)(PPh₃) (2), which may also be produced from (1) by thermolysis with PPh₃ in THF. Compound (2) has been fully characterized in solution by spectroscopy and in the solid state by a single crystal X-ray diffraction analysis at 277 K, and its structure is compared with that of the parent cluster, (1). Using the same synthetic procedures, the tricyclohexylphosphine analogue, Ru₆C(CO)₁₃( ₃- ^{2 2 2}-C₁₆H₁₆)(PCy₃) (3), has also been prepared and characterized spectroscopically. A comparison of the chemical shifts of the 577-01 protons in the ¹H-n.m.r. spectra of compounds (1)–(3) together with a variety of other [2.2]paracyclophane and benzene clusters has been made.     

Isotope effect in retention value between55Cr and51Cr in recoll chemistry of Cr/acac/3

Recoiling behaviour of⁵⁵Cr produced by⁵⁴Cr/n, /⁵⁵Cr reaction was studied by choosing solid Cr/acac/₃ or its benzene solution as target material and by using rapid separation technique. The approximate retention value /R-value/ of⁵⁵Cr, defined as the percentage of the activity retained in the benzene phase which was not extracted with an oxalic acid solution, was found to be higher than that of⁵⁵Cr for practically all experimental runs tested /15 runs/. The ratio (⁵⁵Cr/⁵¹Cr) was 1.115±0.027.     

Dielectric study of poly(methyl methacrylate) microcapsules in particular reference to the effect of the frequency dependence of the permittivity of the capsule wall

The dielectric behavior of poly(methyl methacrylate) (PMMA) microcapsules was analyzed theoretically by taking account of the frequency dependence of the relative permittivity _s and the electrical conductivity _s of the capsule wall. For comparison, similar analysis was applied to polystyrene (PS) microcapsules which have frequency-independent _s and _s . The behavior of _s and _s of the PMMA microcapsules was assumed to be represented by a dielectric relaxation of them-th power type on the basis of dielectric data on underwater PMMA films. By means of a theory of the interfacial polarization, some consideration was carried out regarding the effect of the frequency dependence of _s and _s on the dielectric behavior of the PMMA microcapsules. The consideration led to predictions that the frequency dependence of _s and _s causes (i) the variation in the relaxation intensity with the change in the conductivity of suspending medium, (ii) the frequency dependence of the permittivity at low frequencies and (iii) the frequency dependence of the conductivity at high frequencies. The theoretical prediction (i) was verified by observed data, (ii) and (iii) remaining unverified owing to the experimental difficulty.     

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.     

Efficiency calibration and summation effects in gamma-ray spectrometry

Precise, absolute -ray efficiences ( ) and total efficiences ( _T), have been measured at various distances from the detector, using a set of standards. The observed linear variation of and _T as well as / _T with E and provides a simple means of interpolation and extrapolation. Experimental coincidence summation effects were determined for various nuclides and compared with calculated values. The results are found to be in good agreement with each other.