Molecular aggregation in liquid water: Laplace spectra and spectral clustering of H-bonded network

Application of the spectral clustering method based on the analyses of the Laplace matrix is an acceptable indicator of the global properties of H-bonded network. The first peak of the Laplace spectra contains six eigenvalues. These results suggest that six communities are always formed in our simulated systems independently of the number of molecules in the cubic box. We showed that the H-bonded environment on the surface of the clusters is different from what can be found inside of the clusters. The fraction of four-coordinated molecules is significantly larger in the case of surface molecules. Our work emphasizes that the periodic boundary conditions always cause clustering in the system

Quantum chaos in one dimension?

In this work we investigate the inverse of the celebrated Bohigas-Giannoni-Schmit conjecture. Using two inversion methods we compute a one-dimensional potential whose lowest N eigenvalues obey random matrix statistics. Our numerical results indicate that in the asymptotic limit, N->infinity, the solution is nowhere differentiable and most probably nowhere continuous. Thus such a counterexample does not exist.Comment: 7 pages, 10 figures, minor correction, references extende

Okos, fenntartható és biztonságos városok = Smart sustainable and safe cities

Smart, sustainable and safe cities. But how can a traditional metropolis achieve this complex aim? What facts are go handed together with the sustainability and the safety expected by the townsmen? How could we improve our city better all by ourselves? What kinds of technological side has got a smart city’s construction and development? We could easily illustrate the answers several numbers from among the urban infrastructures. At the same time in our sight the urban traffic infrastructure in the city's fabric such as the vascular system which encompassed human bodies. The vehicular traffic in cities is almost look likes the flow of the blood in our body. Accordingly, we will point out the local transport system of the city only subjective way. The reason of the above applied method is that we would like to analyse the main qualities of the clever city transport subsystem

Okos, fenntartható és biztonságos városok = Smart sustainable and safe cities

Smart, sustainable and safe cities. But how can a traditional metropolis achieve this complex aim? What facts are go handed together with the sustainability and the safety expected by the townsmen? How could we improve our city better all by ourselves? What kinds of technological side has got a smart city’s construction and development? We could easily illustrate the answers several numbers from among the urban infrastructures. At the same time in our sight the urban traffic infrastructure in the city's fabric such as the vascular system which encompassed human bodies. The vehicular traffic in cities is almost look likes the flow of the blood in our body. Accordingly, we will point out the local transport system of the city only subjective way. The reason of the above applied method is that we would like to analyse the main qualities of the clever city transport subsystem

The influence of cations on the dipole moments of neighboring polar molecules

It is shown that the dipole moment of polar (water, methanol, formamide, acetone and acetonitrile) molecules in the neighborhood of a cation is increased primarily by polarization from the bare electrostatic charge of the cation, although the effective value of the latter is somewhat reduced by "back donation" of electrons from neighbouring polar molecules. In other words, the classical picture may be viewed as if a point charge slightly smaller than the nominal charge of the cation would be placed at the cation site. It was found that the geometrical arrangement of the polar molecules in the first solvation shell is such that their mutual polarization reduces the dipole moments of individual molecules, so that in some cases they become smaller than the dipole moment of the free protic or aprotic molecule. We conjecture that this behavior is essentially a manifestation of the Le Chatellier-Braun principle

Composition, morphology and electrical transport properties of Co-Pb electrodeposits

Bath compositions were elaborated for the codeposition of Co and Pb by taking into account the chemical compatibility of Co2+ and Pb2+ with the appropriate anions. Electrolytes containing either acetate, chloride or nitrate anions were tested, but only the acetate bath proved to be appropriate for the preparation of compact Co-Pb films. Deposits were obtained with constant current, with constant potential or by using various current and potential pulses in order to investigate the possibility of multilayer formation. The variation in deposit composition as a function of the deposition parameters was elucidated by using cyclic voltammetry, current transient measurements and gravimetry. X-ray diffraction (XRD) patterns recorded for two-pulse plated deposits revealed a nanocrystalline structure with grain sizes in the range 5 to 20 nm. The XRD peaks could be well indexed to pure face-centered cubic Co and Pb, indicating that the Pb codeposited with Co is not dissolved in Co but is segregated. Both the d.c.-plated and the two-pulse plated deposits exhibited anisotropic magnetoresistance without an indication for a noticeable giant magnetoresistance contribution. This means that the observed magnetoresistance arises from spin-dependent electron scattering events dominantly within the sufficiently large Co regions and not along electron paths between two Co regions via the Pb regions. Low-temperature resistivity measurements revealed a superconducting transition slightly below that of pure Pb. This may be ascribed to a proximity effect: the ferromagnetic Co grains suppress somewhat the superconductivity of the Pb phase due to the nanoscale phase mixture of the two constituents