tt *-Geometry on the Big Phase Space

The big phase space, the geometric setting for the study of quantum cohomology with gravitational descendants, is a complex manifold and consists of an infinite number of copies of the small phase space. The aim of this paper is to define a Hermitian geometry on the big phase space. Using the approach of Dijkgraaf and Witten (Nucl Phys B 342:486–522, 1990), we lift various geometric structures of the small phase space to the big phase space. The main results of our paper state that various notions from tt ^*-geometry are preserved under such liftings.     

Uniqueness properties of higher order dispersive equations

In this paper we study unique continuation properties of solutions to higher (fifth) order nonlinear dispersive models. The aim is to show that if the difference of two solutions of the equations, u₁−u₂, decays sufficiently fast at infinity at two different times, then u₁≡u₂.     

Properties of cucurbit[8]uril adsorption layer at the electrode/solution interface

1. Download high-res image (190KB)
2. Download full-size image

     

Ultrafast nuclear dynamics induced by photodetachment of Ag2- and Ag2O2-: oxygen desorption from a molecular silver surface

Femtosecond nuclear dynamics of mass-selected neutral Ag2 and Ag2O2 clusters are investigated with the 'negative ion-to neutral-to positive ion'(NeNePo) technique. For the bare silver dimer, wave packet dynamics occurring in the neutral electronic ground state and in the first excited triplet state are observed after photodetachment from the anion with 3.05 eV photon energy. While the dynamics in the ground state lead to an oscillatory structure in the NeNePo-pump-probe spectra with a vibrational constant of 185 cm-1, the dynamics in the triplet state are assigned to a bound-free transition leading to dissociation. Photodetachment from the Ag2O2- complex results in the desorption of O2. The experimental data clearly show the influence of the desorbing oxygen ligand on the nuclear dynamics of the silver dimer inducing a red shift in the vibrational frequency and an intensity enhancement of the oscillatory signal.     

HOMOPOLYMERIZATION AND COPOLYMERIZATION OF VINYL ACETATE IN NON-IONIC ICROEMULSIONS. I. A STUDY OF HOMOGENEITY DOMAINS

Abstract

The homogeneity ranges of the systems consisting of the monomer (vinyl acetate or vinyl acetate + di-2-ethyl hexil maleate), cosurfactant (ethanol, n-propanol, n-butanol), surfactant (nonylphenol ethoxylate with 25 moles of ethylene oxide) and water were studied. Addition of the more hydrophobic comonomer requires utilization of a more hydrophobic cosurfactant. The increase of surfactant concentration entails the widening of the homogeneity range. The effect of the cosurfactants mentioned is accounted for by the modification of the cluster structure of water. Therefore the refractive indexes and the signals of protons in NMR spectra vary non-linearly with the composition of homogeneous systems. DSC analysis of the systems obtained has come out with two crystallization temperatures of water undercooled to ?60°C in systems of concentrations close to those of organic and aqueous phases. The results plead for the existence of a structure which differs from that of the ideal solutions of the systems studied.     

Electronic and structural properties of black phosphorene doped with Si,B and N

The electronic and structural properties of substitutional and doped phosphorene with B, N and Si were studied using first principles calculations based on density functional theory. Moreover, electronic and structural properties of functionalized phosphorene slowly increasing the concentration of doping was investigated. Phosphorene strongly binds with doped functionalization; B doped phosphorene is the most stable configuration studied. Si doped phosphorene maintains the semiconductor characteristic. B and N doped phosphorene present n-type and p-type semiconductors, respectively. Doped phosphorene with odd number of Si is a semiconductor material, doped phosphorene with an odd number of B has n-type semiconductor characteristic, and doped phosphorene with odd number of N atoms has a p-type semiconductor behaviour. Doped phosphorene with even number of Si has a metallic characteristic, while B and N doped phosphorene with even number present a semiconductor behaviour. This work reveals that phosphorene electronic properties could be changed by introducing the dopants on the system, and the properties are affected by the increasing number of dopants on phosphorene sheet.     

Synthesis of Nb2O5·nH2O nanoparticles by water-in-oil microemulsion

Hydrous niobium oxide (Nb₂O₅·nH₂O) nanoparticles had been successfully prepared by water-in-oil microemulsion. They were characterized by X-ray diffraction (XRD), thermal analysis (TG/DTG), Fourier transform infrared spectroscopy (FTIR), BET surface area measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the nanoparticle was exactly Nb₂O₅·nH₂O with spherical shape. Their BET surface area was 60 m² g⁻¹. XRD results showed that Nb₂O₅·nH₂O nanoparticles with crystallite size in nanometer scale were formed. The crystallinity and crystallity size increased with increasing annealing temperature. TT-phase of Nb₂O₅ was obtained when the sample is annealed at 550 °C.     

The Crystal and Molecular Structure of Atipamezole Base and Atipamezole Hydrochloride

Abstract  

Crystal structures of alpha₂-adrenergic antagonist atipamezole base (1) and its hydrochloric acid salt (2) have been determined using X-ray diffraction methods. Atipamezole base crystallized in the monoclinic space group P2₁, with unit cell parameters a = 13.238(4), b = 9.747(4), c = 14.609(5) ?, β = 107.75(4)o, V = 1,795.3(12) ?³ and Z = 6 (three independent molecules of 1). Atipamezole hydrochloride crystallized in the monoclinic space group Cc, with unit cell parameters a = 12.052(1), b = 32.561(9), c = 13.668(5) ?, β = 102.64(1)o, V = 5,233(2) ?³ and Z = 16 (four independent molecules of 2). Each of the three atipamezole moieties in 1 has an intramolecular C–H···N H-bond. In both structures the molecules are H-bonded to form extended chains.