Correlation between damping of sea ripples and other physico-chemical properties in coastal marine water

Summary Rheological data of the marine surface obtained from frequency wave spectra are compared with physico-chemical analyses of water samples drawn simultaneously from half a meter below the interface in fifteen preselected locations along a stretch of Tuscan Coast located between the Arno and Serchio rivers. The study has proved the presence of adsorption films tightly related to the rivers' plumes. A good correlation between the anionic surfactants detected in gas-bubble-enriched samples and the adsorbent excess measured at the surface has been observed. Implications of the multifrequency radar remote-sensing technique are here discussed.     

The electron transfer rate of large TPA based compounds: a joint theoretical and electrochemical approach

A series of triphenylamine (TPA) based compounds is investigated by means of density functional theory and cyclic voltammetry. Using the Nicholson's formalism, the measured deltaE(p) are correlated with B3LYP/6-31G* calculated reorganisation energies (lambda), elucidating the trend followed by the electron transfer rate of these compounds. Besides the direct dependency upon the dimension of the cationic fragment contributing to the hole stabilisation, the lambdas are tuned by the symmetry local to the TPA units, as evidenced by the structural relaxation of the cations. MDTAB shows the interesting combination of low ionisation potential (IP) and low lambda. This can make this compound interesting for practical applications in organic light emitting diode (OLEDs) devices, due to the direct correlation of the IP and lambda with the hole transfer efficiency to the anode, along with the hole mobility.     

Investigation of quantum phase transitions using multi-target DMRG methods

In this paper we examine how the predictions of conformal invariance can be widely exploited to overcome the difficulties of the density-matrix renormalization group near quantum critical points. The main idea is to match the set of low-lying energy levels of the lattice Hamiltonian, as a function of the systems size, with the spectrum expected for a given conformal field theory in two dimensions. As in previous studies this procedure requires an accurate targeting of various excited states. Here we discuss how this can be achieved within the DMRG algorithm by means of the recently proposed Thick-restart Lanczos method. As a nontrivial benchmark we use an anisotropic spin-1 Hamiltonian with special attention to the transitions from the Haldane phase. Nonetheless, we think that this procedure could be generally valid in the study of quantum critical phenomena.Received: 20 May 2004, Published online: 5 November 2004PACS: 75.40.Mg Numerical simulation studies - 05.10.Cc Renormalization group methods - 75.10.Pq Spin chain models     

Rising of gas bubbles in an aqueous medium in presence of surfactants

Summary Experiments based on the direct comparison of the gas-bubble rising times in a surfactant aqueous solution, in respect to those in pure water, give support to the hypothesis that a rising path of many metres is needed to reach the saturation of the adsorption process on bubbles (0.2÷0.3) cm in diameter. A maximum is evidenced in thet/t ₀ ratiovs. surfactant concentration at the highest concentrations tested. An explanation, on a qualitative basis, of the appearance of the observed maximum is proposed. Work presented at the IV Congress of the CNR (National Research Council) National Group of the Atmosphere and Ocean Physics, Rome, June 22–24, 1987.     

High-Resolution Infrared Spectrum of BrCN in the nu(2) and nu(1)/2nu(2) Regions

The vibrational excitations of bent triatomic molecules, including both bending and stretching vibrations, are studied in the framework of the U(4) algebra. For the bent triatomic molecules H(2)O and H(2)S, the highly excited vibrational levels (up to 14) are obtained using the U(4) algebraic approach. We have found that the spectra are made up of clustering structure. The number of levels in one cluster depends on the total quanta of stretching and bending. In addition, some other properties are also discussed. Copyright 2000 Academic Press.     

In situ isobaric lipid mapping by MALDI–ion mobility separation–mass spectrometry imaging

The highly diverse chemical structures of lipids make their analysis directly from biological tissue sections extremely challenging. Here, we report the in situ mapping and identification of lipids in a freshwater crustacean Gammarus fossarum using matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) in combination with an additional separation dimension using ion mobility spectrometry (IMS). The high‐resolution trapped ion mobility spectrometry (TIMS) allowed efficient separation of isobaric/isomeric lipids showing distinct spatial distributions. The structures of the lipids were further characterized by MS/MS analysis. It is demonstrated that MALDI MSI with mobility separation is a powerful tool for distinguishing and localizing isobaric/isomeric lipids.