Analytic wave functions and energies for two-dimensional \mathcal{P}\mathcal{T} -symmetric quartic potentials

Analytic wave functions and the corresponding energies for a class of the $ \mathcal{P}\mathcal{T} $ -symmetric two-dimensional quartic potentials are found. The general form of the solutions is discussed.     

Positive-ion fragmentation in matrix-assisted laser desorption/ionization tandem time of flight mass spectrometry of synthetic analogs of the O-specific polysaccharide of Vibrio cholerae O:1

Saccharides (mono- to hexamers) that mimic the terminal epitopes of O-antigens of Vibrio cholerae O:1, serotypes Ogawa and Inaba have been studied by matrix-assisted laser desorption/ionization tandem time-of-flight (MALDI ToF/ToF) mass spectrometry (MS). Cationized adducts are the characteristic ions formed through the capture of sodium or potassium cations under MALDI MS conditions. Three characteristic pathways dominate in the fragmentation of model substances under MALDI ToF/ToF collision-induced dissociation MS/MS conditions of measurement. The first is the elimination which shortens the length of the oligosaccharide. In this way, conversion of the Ogawa to Inaba fragments takes place under the conditions of measurement. In the second, the conjugated transfer of electrons in the upstream unit of oligosaccharides takes place. The third route brings about the elimination of one alpha-hydroxy-gamma-butyrolactone molecule from the 4-(3-deoxy-L-glycero-tetronamido) group. The MALDI ToF/ToF MS/MS provided sufficient information about molecular mass, the number of saccharide residues, the structure of saccharides, the C(4)- amide of 3-deoxy-L-glycero-tetronic acid (DGT) of the compounds investigated, and allows to distinguish between Ogawa and Inaba serotypes.     

Negative electrospray, ion trap multistage mass spectrometry of synthetic fragments of the O-PS of Vibrio cholerae O:1

Saccharides (mono through hexasaccharides) that mimic the terminal epitopes of O-antigens of Vibrio cholerae O:1, serotypes Ogawa and Inaba, were studied by electrospray ion trap (ESI IT) mass spectrometry (MS) in the negative mode. Anionized adducts are the characteristic ions formed by the capture of H(3)O(2)(-) under the condition of ESI MS analysis. The reactive species are produced by reaction of hydroxyl anions with the molecule of water. Thus the [M + H(3)O(2)](-) have the highest m/z value in the ESI IT negative mass spectra. After dissociation of adducts by loss of 2H(2)O the [M-H](-) ions are produced. The fragmentation pathways were confirmed by multistage measurements (MS(n)). The predominant pathway of fragmentation of the mono- and oligomers is the elimination of a molecule of alpha- hydroxy--gammabutyrolactone from the 4-(3-deoxy-L-glycero-tetronamido) group. The other characteristic pathway occurs by shortening the length of oligosaccharides. In this way, conversion of the Ogawa to Inaba fragments takes place under the conditions of measurement. Negative ESI MS/MS provided sufficient information about molecular mass, the number of saccharide residues, basic structure of saccharides, about the tetronamide part of the compounds investigated and allowed Ogawa and Inaba serotypes to be distinguished.     

Optical sensing system for ATP using porphyrin-alkaloid conjugates

Tetrabrucin-porphyrin as a sensor for ATP was designed and tested; selectivity for ATP was proved in the presence of ADP and AMP.     

Conformational flexibility of L-alanine zwitterion determines shapes of Raman and Raman optical activity spectral bands

Detailed analysis of Raman and Raman optical activity (ROA) of L-alanine zwitterion (ALAZW) revealed that shapes of the spectral bands are to a large extent determined by the rotation of the NH(3)(+), CO(2)(-), and CH(3) groups. Aqueous solution ALAZW spectra were measured down to 100 cm(-1) and compared to complex simulations based on ab initio (B3LYP/CPCM/6-31++G**) computations of molecular energies and spectral parameters. The bands exhibit different sensitivities to the motion of the rotating group; typically, for more susceptible bands the Raman signal becomes broader and the ROA intensity decreases. When these dynamical factors are taken into account in Boltzmann averaging of conformer contributions, simulated spectra not only better agree with the experiment, but shapes of the rotational potentials can be estimated. Effects of the molecular flexibility could be also demonstrated on differences in Raman spectra of the solution, crystalline, and glass (gellike) solid states of ALAZW. Experimental Raman and ROA spectra of four model dipeptides of different rigidities (Ala-Pro, Pro-Ala, Pro-Gly, and Gly-Pro) indicate that the broadening of spectral lines can be used as a general site-specific indicator of molecular rigidity or flexibility.     

A photoelectron spectroscopy study of ultra-thin epitaxial alumina layers grown on Cu(111) surface

Thin epitaxial alumina layers were grown on the Cu(111) surface using simultaneous aluminum deposition and oxygen exposure. Different substrate temperatures during the deposition resulted in layers with different thicknesses, growth rates, crystallinity and epitaxy. Low energy electron diffraction measurements confirmed the epitaxial growth for substrate temperatures above 870 K. The Al 2p doublet was studied by means of photoelectron spectroscopy in order to determine the alumina termination at the metal-oxide interface. A strong dependence on the preparation temperature was found and both aluminum and oxygen terminated interfaces were created.     

Modification of terminating species and band alignment at the interface between alumina films and metal single crystals

Thin epitaxial alumina films were grown on Cu(111), Cu–9 at.%Al(111), Ni(111) and NiAl(110) single crystals. The alumina films grew in such a manner that hexagonal or pseudo-hexagonal oxygen lattices were parallel to the surface of the substrates. Photoelectron spectra were obtained either with synchrotron or Al K-alpha radiation. We measured Al 2p spectra and determined the atomic species that terminated the interface between the alumina films and the substrates. The influence of Al in the substrates on the species that terminated the interface has been discussed based on thermodynamics. From valence band spectra, p-type Schottky barrier height (energy difference between the Fermi level of the metallic substrates and the valence band maximum of the alumina films, band offset) was determined. Differences in interface terminating species resulted in variations in p-type Schottky barrier height, or band alignment.     

Are economically advanced countries more efficient in basic and applied research?

Research and development (R&D) of countries play a major role in a long-term development of the economy. We measure the R&D efficiency of all 28 member countries of the European Union in the years 2008–2014. Super-efficient data envelopment analysis (DEA) based on robustness of classification into efficient and inefficient units is adopted. We use the number of citations as output of basic research, the number of patents as output of applied research and R&D expenditures with manpower as inputs. To meet DEA assumptions and to capture R&D characteristics, we analyze a homogeneous sample of countries, adjust prices using purchasing power parity and consider time lag between inputs and outputs. We find that the efficiency of general R&D is higher for countries with higher GDP per capita. This relation also holds for specialized efficiencies of basic and applied research. However, it is much stronger for applied research suggesting its outputs are more easily distinguished and captured. Our findings are important in the evaluation of research and policy making.     

Structure and NMR properties of 6‐substituted‐5,6‐dihydrobenzo[c]phenanthridine alkaloids

We report a preparation of new 6‐substituted‐5,6‐dihydrobenzo[c]phenanthridines by the reaction of azoles with quaternary benzo[c]phenanthridine alkaloids sanguinarine and chelerythrine. The prepared compounds have been characterized by NMR spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction. Conformational behaviors of carbazole derivatives in solution have been investigated by low‐temperature NMR experiments. Barriers to rotation around newly formed C6–N bonds were determined to be 12–13 kcal/mol. Quantum chemical calculations have been used to reproduce the experimental observations. Large structural effects on several ¹H NMR resonances were observed experimentally, analyzed by Density Functional Theory (DFT) calculations at B3LYP/6‐311+G(d,p)/PCM level, and interpreted by ring‐current effects of the benzo[c]phenanthridine and carbazole units. Copyright © 2013 John Wiley & Sons, Ltd.