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1.
We observe that a term of the WZW-type can be added to the Lagrangian of the Poisson σ-model in such a way that the algebra of the first class constraints remains closed. This leads to a natural generalization of the concept of Poisson geometry. The resulting “WZW–Poisson” manifold M is characterized by a bivector Π and by a closed three-form H such that 1/2[Π,Π]Schouten=H,ΠΠΠ. 相似文献
2.
Dorota G?azowska Janusz Matkowski 《Journal of Mathematical Analysis and Applications》2007,331(2):1187-1199
The invariance of the geometric mean G with respect to the Lagrangian mean-type mapping (Lf,Lg), i.e. the equation G○(Lf,Lg)=G, is considered. We show that the functions f and g must be of high class regularity. This fact allows to reduce the problem to a differential equation and determine the second derivatives of the generators f and g. 相似文献
3.
Gravimetric measurements of thermodesorption of n-hexane and n-heptane were performed under quasi-equilibrium conditions. Differential thermodesorption profiles for ZSM-5 and ZSM-11 showed two peaks, but for Y zeolites, only one thermodesorption peak was observed. A model function, derived from the Langmiur adsorption model, was fitted to the experimental data, and the model parameters (the adsorption entropy and enthalpy) were estimated. The two-step desorption profiles observed for ZSM-5 and ZSM-11 were attributed to the commensurate freezing effect, i.e. a transition in the adsorbed phase resulting in ordering of the adsorbed molecules in the zeolite channels. The results observed for ZSM-11 indicate that the zigzag channels typical for ZSM-5 micropore system are not necessary for this transition to occur. 相似文献
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6.
Maria Nowakowska Mirosława Smoluch Dorota Sendor 《Journal of inclusion phenomena and macrocyclic chemistry》2001,40(3):213-219
The effect of -, - and -cyclodextrin onthe photochemical stability of 7-amino-4-methylcoumarin (C120)was studied. Using spectroscopic techniques (UV/Vis absorption spectroscopy, fluorescence, fluorescence anisotropy and circular dichroism) combined with HPLC/MS and MS analysis it was demonstrated that addition of -cyclodextrin to the aqueoussolution of C120 markedly inhibits the photodegradation of that dye. This results from theformation of an inclusion complex between C120 and -cyclodextrin. 相似文献
7.
Grażyna Janowska Teresa Mikołajczyk Dorota Wołowska-Czapnik M. Boguń 《Journal of Thermal Analysis and Calorimetry》2005,82(1):129-135
The paper discusses the thermal properties of alginate fibres made from alginic acid or sodium alginate and from alginates
substituted with divalent metal ions during the fibre-forming stage. Alginate fibres with an addition of silica nanoparticles
have also been examined. The selection of fibre-forming parameters was intended to obtain the best either sorption or strength
properties depending on the specific fibre application. Thermal curves of the fibres under investigations obtained by under
air atmosphere and differential scanning calorimetry (DSC) under neutral gas atmosphere have been interpreted from the view
of physical and chemical changes in the fibre-forming material. Based on thermogravimetric curves, the fibre thermal stability
indices have been determined. It has been found that the addition of silica nanoparticles exerts a positive influence on the
thermal properties of the examined fibres. 相似文献
8.
The aim of present study is to select the best methodology in the frame of the Density Functional Theory (DFT), which may be employed to study the cobalamin complexes. Our discussion is limited to two approaches, one in which hybrid B3LYP and UB3LYP functionals are used, and the second in which geometry parameters are calculated within LDA-VWN functional, and energies of the investigated systems are computed within RPBE functional. Results of performed calculations show that both methodologies can be successfully applied to study cobalamin derivatives. Probably because of the small ligand binding energies in the studied complexes, the B3LYP and UB3LYP functionals may be used only to predict the pattern of changes in the binding energies. The use of the RPBE functional, originally parameterized to reproduce in a proper way the chemisorption energies of the small molecules on the metallic surfaces, allows to improve their values so as they fit into experimental data. Geometry parameters of the investigated complexes computed within both approaches are in good agreement with the experimental values. Interatomic distances are a little overestimated while calculated within both hybrid functionals, what is in contrast to VWN functional results. The latter, in general, gives shorter distances as observed experimentally. 相似文献
9.
Dorota Gryko DanielT. Gryko Hanna Sierzputowska‐Gracz Piotr Piatek Janusz Jurczak 《Helvetica chimica acta》2004,87(1):156-166
The efficient synthesis of eight new macrocyclic amides (lactams) via reaction of diesters with diamines under normal dilution conditions is described. The role of intermolecular H‐bond formation and steric hindrance is discussed based on 1H‐ and 15N‐NMR studies of appropriate model compounds. Principles for the optimal choice of esters that can be efficiently transformed into diamides have been developed. 相似文献
10.
In the framework of noncommutative geometry we describe spinor fields with nonvanishing winding number on a truncated (fuzzy) sphere. The corresponding field theory actions conserve all basic symmetries of the standard commutative version (space isometries and global chiral symmetry), but due to the noncommutativity of the space the fields are regularized and they contain only a finite number of modes.Part of the Project P8916-PHY of the Fonds zur Förderung der wissenschaftlichen Forschung in Österreich. 相似文献