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51.
Králik M Kratky V De Rosso M Tonelli M Lora S Corain B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(1):209-214
The polymer framework of a resin-based catalyst built up with Pd nanoclusters (ca. 3 nm) dispersed inside the nanoporous domains of a thermally stable gel-type polyacrylic resin exhibits a good chemical stability under 5 bar H(2) at 40 degrees C for reasonable contact times. Chemical and physico-chemical integrity of the polymer framework are checked with a variety of instrumental analytical methods. Catalyst reusability turns out to be quite good. 相似文献
52.
C. Balarew D. Rabadjieva S. Tepavitcharova C. Christov O. Angelova 《Journal of solution chemistry》1999,28(7):949-958
Crystallization of 2RbBr · MnBr2 · 2H2O, the only double salt obtained under standard conditions from saturated aqueous rubidium–manganese bromide solutions, was theoretically predicted using the hard and soft Lewis acids and bases concept and Pauling's rules. The RbBr—MnBr2—H2O system was thermodynamically simulated by the Pitzer model assuming a solubility diagram of three branches only: RbBr, 2RbBr · MnBr2 · 2H2O and MnBr2 · 4H2O. The theoretical result was experimentally proved at 25°C by the physicochemical analysis method and formation of the new double salt 2RbBr · MnBr2 · 2H2O was established. It was found to crystallize in a triclinic crystal system, space group –P1, a = 5.890(1) Å, b = 6.885(1) Å, c = 7.367(2) Å, = 66.01(1)°, = 87.78(2)°, = 84.93(2)°, V = 271.8(1) Å3, Z = 1, D
x = 3.552 g-cm–3. The binary and ternary ion interaction parameters were calculated and the solubility isotherm was plotted. The standard molar Gibbs energy of the synthesis reaction, rG
m
o
, of the double salt 2RbBr · MnBr2 · 2H2O from the corresponding simple salts RbBr and MnBr2 · 4H2O, as well as the standard molar Gibbs energy of formation, fG
m
o
, and standard molar enthalpy of formation fH
m
o
of the simple and double salts were calculated. 相似文献
53.
Toms de las Casas Engel Beatriz Lora Maroto Antonio García Martínez Santiago de la Moya Cerero 《Tetrahedron: Asymmetry》2008,19(17):2003-2006
Two series of structurally related enantiopure isoborneols (10-amino- and 10-amino-10-oxoisoborneols) have been obtained from ketopinic acid and compared as chiral ligands for the enantioselective addition of diethylzinc to benzaldehyde in the absence of Ti(O-i-Pr)4. The results obtained (chemical yields and enantiomeric excesses) show that identical structural factors (functionalization grade and symmetry group) exert very different effects on both series. The observed differences have been rationalized on the basis of the coordination ability of each ligand type to form the corresponding reactive zinc-chelate catalyst. 相似文献
54.
For the first time symmetrized Clebsch-Gordan coefficients for corepresentations, the so called 2D- and 3D-symbols (analogous to the Wigner 2j- and 3j-symbols correspondingly) are calculated, and tabulated for all single- and double-valued corepresentations of all 90 antiunitary magnetic point groups. 相似文献
55.
Maia Angelova 《Acta Physica Hungarica A》2004,19(3-4):347-351
An algebraic model based on Lie-algebraic techniques is applied to vibrational molecular thermodynamics. The model uses the isomorphism between the SU(2) algebra and the one-dimensional Morse oscillator. A vibrational high-temperature partition function and the related thermodynamic properties are derived in terms of the parameters of the model. The anharmonic vibrations are described as anharmonic q-bosons using a first-order expansion of a quantum deformation. It is shown, that this quantum deformation is related to the shape of the Morse potential. 相似文献
56.
Larsson M Ehlerding A Geppert WD Hellberg F Kalhori S Thomas RD Djuric N Osterdahl F Angelova G Semaniak J Novotny O Arnold ST Viggiano AA 《The Journal of chemical physics》2005,122(15):156101
Product branching ratios and thermal rate coefficients for the dissociative recombination of C3D(+)7 and C4D(+)9 have been measured in the ion storage ring CRYRING. The results for C3D(+)7 are believed to be slightly more accurate than those obtained earlier for C3H(+)7. Only the C-C bond breaking channels could be measured for C4D(+)9 and were found to be in excellent agreement with earlier data. 相似文献
57.
Many mechanical systems consist of continuum mechanical structures, having either linear or nonlinear elasticity or geometry, coupled to nonlinear oscillators. In this paper, we consider the class of linear continua coupled to mechanical pendula. In such mechanical systems, there often exist several natural time scales determined by the physics of the problem. Using a time scale splitting, we analyze a prototypical structural-mechanical system consisting of a planar nonlinear pendulum coupled to a flexible rod made of linear viscoelastic material. In this system both low-dimensional and high-dimensional chaos is observed. The low-dimensional chaos appears in the limit of small coupling between the continua and oscillator, where the natural frequency of the primary mode of the rod is much greater than the natural frequency of the pendulum. In this case, the motion resides on a slow manifold. As the coupling is increased, global motion moves off of the slow manifold and high-dimensional chaos is observed. We present a numerical bifurcation analysis of the resulting system illustrating the mechanism for the onset of high-dimensional chaos. Constrained invariant sets are computed to reveal a process from low-dimensional to high-dimensional transitions. Applications will be to both deterministic and stochastic bifurcations. Practical implications of the bifurcation from low-dimensional to high-dimensional chaos for detection of damage as well as global effects of noise will also be discussed. 相似文献
58.
G. Poletti F. Orsini D. Batani A. Bernardinello T. Desai J. Ullschmied J. Skala B. Kralikova E. Krousky L. Juha M. Pfeifer Ch. Kadlec T. Mocek A. Präg O. Renner F. Cotelli C. Lora Lamia A. Zullini 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2004,30(2):235-241
Soft X-ray Contact Microscopy (SXCM) of Caenorhabditis elegans nematodes with typical length
m and diameter
m has been performed using the PALS laser source of wavelength
m and pulse duration
ps. Pulsed soft X-rays were generated using molybdenum and gold targets with laser intensities
W/cm2. Images have been recorded on PMMA photo resists and analyzed using an atomic force microscope operating in contact mode. Cuticle features and several internal organs have been identified in the SXCM images including lateral field, cuticle annuli, pharynx, and hypodermal and neuronal cell nuclei.Received: 18 February 2004, Published online: 29 June 2004PACS:
42.62.Be Biological and medical applications - 07.85.Tt X-ray microscopes - 87.59.Bh X-ray radiographyA color version of the figures is available in electronic form at . 相似文献
59.
A quasianalytical theory of tunnel ionization is developed that is applicable to general complex systems, such as large molecules. Our analysis reveals strong deviations from conventional tunnel ionization theories, dependent upon the system's geometry, angular momentum, and polarizability. A comparison of our theory with recent C(60) ionization experiments yields reasonable agreement. 相似文献
60.
A simple model extending Lie algebraic techniques is applied to the analysis of thermodynamic vibrational properties of diatomic molecules. Local anharmonic effects are described by means of a Morse-like potential and the corresponding anharmonic bosons are associated with the SU(2) algebra. The total number of anharmonic bosons, fixed by the potential shape, is determined for a large number of diatomic molecules. A vibrational high-temperature partition function and the related thermodynamic functions are derived and studied in terms of the parameters of the model. The idea of a critical temperature is introduced in relation to the specific heat. A physical interpretation in terms of a quantum deformation associated with the model is given. 相似文献