Symmetries of Cauchy-Riemann spaces

We simplify and generalize Cartan's results on Cauchy-Riemann spaces admitting continuous groups of automorphisms. We describe all such spaces in terms of local coordinates.     

Photochemical synthesis of 7H-indolo[1,2-a]quinolinium salts - a new ring system

Photodehydrocyclization of 1-phenyl-2-/2-arylethenyl/-3,3-dialkyl-3H-indolium cations leads in very good yield to 7H-indolo[1,2-a]quinolinium cations.     

Preparation and semiconducting properties of Th3As4

The resistivity, thermoelectric power and Hall constant in the temperature range of 78–830 K were determined for polycrystalline Th₃As₄ samples obtained by annealing thin thorium slabs in arsenic vapour. The samples examined were n-type semiconductors with a carrier concentration ranging from 1.0 × 10¹⁸cm^?3 to 2.8 × 10¹⁸ cm^?3 for which the effective mass was found to be equal to 0.55–0.76m₀. The Hall mobility, about 450cm²V^?1s^?1 at room temperature, obeys a $\text{T}{}^{\mathrm{<mtext>?3</mtext><mtext>2</mtext>}}$ law at high temperatures. On the basis of the electrical measurements the forbidden gap of Th₃As₄ was found to be equal to 0.43 eV.     

Surface photovoltage spectroscopy and surface piezoelectric effect in GaAs

“Real” (111) surfaces of n-type GaAs were investigated employing surface photovoltage spectroscopy and the surface piezoelectric effect. Surface states at the energy position E_c ? E_t ? 0.72 eV were found on both the Ga and the As surfaces. Both types of surfaces exhibited a barrier of about 0.55 V. No variations in the surface barrier or the energy position of the surface states were observed in various ambients at atmospheric pressure (dry air, wet air, ammonia and ozone). However, the capture cross-section of the surface states for electrons, as determined from the surface piezoelectric effect transients (of the order of 10^?13 cm²), was found to be sensitive to the ambient. It decreased in wet air and increased in ozone. This effect was more pronounced on the As than on the Ga surfaces. Additional surface states were found to be present in the energy region of 0.9 to 1.0 eV, below the bottom of the conduction band. However, their exact energy positions could not be determined due to interference caused by the carrier trapping of the surface states at E_c ? E_t ? 0.72 eV.     

Determination of nonsteroidal antiinflammatory drugs in water samples using liquid chromatography coupled with diode-array detector and mass spectrometry

An analytical method for the determination of trace levels of six different nonsteroidal antiinflammatory drugs (NSAIDs) in water samples has been developed and validated. Environmentally relevant pharmaceuticals were chosen according to human consumption in Poland. Final analysis of the target compounds was performed by RP LC-diode-array detection-MS, whereas sample preparation included an SPE step. For this SPE step, a number of packing materials, such as LiChrolut RP-18, calixarene, Strata-X, BAKERBOND Narc-2, BAKERBOND Polar Plus, BAKERBOND styrene divinylbenzene-1, and Discovery DSC-18, were used, and their respective advantages and disadvantages in this study were discussed. The RP-18 phase was found to be the most retentive for all analytes. The detection limits for compounds in surface waters were varied from 0.005 for diflunisal to 0.095 microg/L for ibuprofen. The average recoveries of NSAIDs from the surface water samples ranged from 80 up to 103%. RSD value is relatively low (from 4% for fenoprofen up to 8% for ibuprofen). The performance of the method was tested with several environmental water samples.     

Nucleation of Pd dimers at defect sites of the MgO(100) surface

Point defects on oxide surfaces are presumed to be preferential nucleation sites for supported metal clusters. Under typical growth conditions, dimers constitute the first step in island nucleation. First-principles calculations on the formation of Pd dimers on regular and defect sites of the MgO(100) surface show that nucleation occurs with large dimer binding energies at divacancies and charged oxygen vacancies (F+ centers), while it is less favorable on steps and neutral F centers. The extensive database of defect trapping/attachment properties gives a firm basis to rationalize recent atomic-force microscopy findings and provides guidelines valid, in general, for ionic substrates.     

Arithmetic Progressions,Prime Numbers,and Squarefree Integers

In this paper we establish the distribution of prime numbers in a given arithmetic progression p l for which ap + b is squarefree.     

May GSH and L-His contribute to intracellular binding of zinc? Thermodynamic and solution structural study of a ternary complex

GSH and L-His are abundant biomolecules and likely biological ligands for Zn(II) under certain conditions. Potentiometric titrations provide evidence of formation of ternary Zn(II) complexes with GSH and L-His or D-His with slight stereoselectivity in favour of L-His (ca. 1 log unit of stability constant). The solution structure of the ZnH(GSH)(L-His)(H2O) complex at pH 6.8, determined by NMR, includes tridentate L-His, monodentate (sulfur) GSH, and weak interligand interactions. Calculations of competitivity of this complex for Zn(II) binding at pH 7.4 indicate that it is likely to be formed in vivo under conditions of GSH depletion. Otherwise, GSH alone emerges as a likely Zn(II) carrier.