Monaural and binaural parameters of Rudolfinum concert halls in Prague

Objective parameters for the evaluation of the Rudolfinum concert hall in Prague, Czech Republic are the focus of the present article. The measured results for Reverberation parameters, Energy parameters, Intelligibility parameters, and Spatial parameters of the building’s two halls are presented and discussed including a comparison with recommended values or theory, as well as several unique architectural and acoustical qualities of the halls. The early lateral energy fraction parameter is measured by the intensity probe method discussed in the supplement. The performance is verified by tests in anechoic and reverberant rooms.     

Tribological properties of heat-treated electroless Ni-P coatings on AZ91 alloy

Influence of heat treatment regime on adhesion and wear resistance of Ni-P electroless coating on AZ91 magnesium alloy is investigated in this work. The pretreated substrate was plated using a bath containing nickel sulphate, sodium hypophosphite and sodium acetate as main constituents. The coated samples were heat treated at 400-450 °C for 1-8 h. Adhesion of coating was estimated from the scratch test with an initial load of 8.80 N. Wear resistance was studied using the pin-on-disc method. It was found that there is no significant dependence of the coating wear resistance on heat treatment regime, as the formation of Al-Ni intermetallic sub-layers that reduce coating adhesion is limited to regions where Al₁₇Mg₁₂ phase is present in the substrate. Moreover, the coating shows good sliding properties due to the formation of oxide glazes in the wear track.     

Three-dimensional potential energy surface of selected carbohydrates' CH/π dispersion interactions calculated by high-level quantum mechanical methods

In this study we present the first systematic computational three‐dimensional scan of carbohydrate hydrophobic patches for the ability to interact through CH/π dispersion interactions. The carbohydrates β‐d‐ glucopyranose, β‐d‐ mannopyranose and α‐l‐ fucopyranose were studied in a complex with a benzene molecule, which served as a model of the CH/π interaction in carbohydrate/protein complexes. The 3D relaxed scans were performed at the SCC‐DFTB‐D level with 3 757 grid points for both carbohydrate hydrophobic sides. The interaction energy of all grid points was recalculated at the DFT‐D BP/def2‐TZVPP level. The results obtained clearly show highly delimited and separated areas around each CH group, with an interaction energy up to ?5.40 kcal mol^?1. The results also show that with increasing H???π distance these delimited areas merge and form one larger region, which covers all hydrogen atoms on that specific carbohydrate side. Simultaneously, the interaction becomes weaker with an energy of ?2.5 kcal mol^?1. All local energy minima were optimized at the DFT‐D BP/def2‐TZVPP level and the interaction energies of these complexes were refined by use of the high‐level ab initio computation at the CCSD(T)/CBS level. Results obtained from the optimization suggest that the CH group hydrogen atoms are not equivalent and the interaction energy at the CCSD(T)/CBS level range from ?3.54 to ?5.40 kcal mol^?1. These results also reveal that the optimal H???π distance for the CH/π dispersion interaction is approximately (2.310±0.030) Å, and the angle defined as carbon‐hydrogen‐benzene geometrical centre is (180±30)°. These results reveal that whereas the dispersion interactions with the lowest interaction energies are quite strictly located in space, the slightly higher interaction energy regions adopt a much larger space.     

Effect of configurational averaging on observables

Effect of the distribution of the structural parameters on the time evolution of the fluorescence intensity is discussed. The influence of this distribution in two limit regimes of the excitation energy transfer — coherent and incoherent one are compared. It is shown that in many cases the fluorescence intensity measurements do not enable to decide between the two regimes. Presented at the Czech-Israeli-German Symposium “Dynamical Processes in Condensed Molecular Systems”, Prague, Czech Republic, 26–30 May 1997.     

Admissible Orders of Jordan Loops

A commutative loop is Jordan if it satisfies the identity x²(yx) = (x²y)x. Using an amalgam construction and its generalizations, we prove that a nonassociative Jordan loop of order n exists if and only if n≧ 6 and n≠ 9. We also consider whether powers of elements in Jordan loops are well‐defined, and we construct an infinite family of finite simple nonassociative Jordan loops. © 2008 Wiley Periodicals, Inc. J Combin Designs 17: 103–118, 2009     

Über Gitterpunkte in mehrdimensionalen Ellipsoiden

Ohne Zusammenfassung