XPS and factor analysis study of initial stages of cerium oxide growth on polycrystalline tungsten

The initial stages of growth of the nanostructured cerium oxide deposited on the polycrystalline tungsten surface by pulsed laser deposition are studied using XPS technique. The population of Ce (III) and Ce (IV) oxidation states in the deposited CeO_2?x layers is determined applying factor analysis method. Tungsten atoms react with oxygen from the cerium oxide nanoparticles already at the room temperature, and a layer of tungsten trioxide is formed at the interface. Gradual heating of the samples up to 900 K leads to the increase of the thickness of WO₃ oxide layer and a partial reduction of Ce (IV) to Ce (III). The spectra of O (1s) photoelectrons are composed from a signal originating from metal oxides and a signal of surface superoxide and hydroxyl groups. Factor analysis was performed on the spectra of Ce (3d) photoelectrons to determine the position, shape, and intensity of the spectral components belonging to Ce (III) and Ce (IV) oxidation states. We propose a new simple method to generate components of the spectroscopic meaning. The basic idea of our method consists in the use of the slightly positive values instead of zeros to the needle test vector. Two components are required to reproduce the original data within the experimental errors. Copyright © 2015 John Wiley & Sons, Ltd.     

Excimer source of radiation for photobiology

A gas-discharge excimer source of visible radiation employing a mixture of mercury diiodide vapor, mercury dibromide vapor, and helium is studied. The emission spectrum of the source covers the range from 370 to 510 nm. About 90% of the radiation power is concentrated in the blue-green spectral region.     

Optical characteristics of barrier discharge plasma based on mixtures of cadmium diiodide vapors with gases

The spectral, integrated, and working life characteristics of the radiation from atmospheric pressure gas discharge plasma based on multicomponent mixtures (cadmium diiodide with helium and small admixtures of molecular nitrogen and xenon) are analyzed. A pulsed barrier discharge (pulse repetition rates 5000, 5500, and 6000 Hz; pulse duration ～150 ns) is used both to produce the gas discharge plasma and to excite the components of the working mixture. Visible radiation is detected from excimer molecules of cadmium monoiodide and cadmium, xenon, and krypton atoms. Regular features are found in the variations of optical plasma characteristics with pumping pulse repetition rate and with component and quantitative mixture composition.     

Frequency domain criteria for robust stability of a family of linear difference equations 1

We provide necessary and sufficient conditions for stability of solutions to linear difference equations with coefficients in a prescribed set. The conditions encompass classes of uncertainty such as interval familiesl^p families, affine families.     

Chiroptical properties of the nonplanar amide chromophore in n-acylaziridines

The optically active 1-acyl-substituted (1R,2R)-2-methyl- and (1R,2S)-2-methoxycarbonylaziridines were synthesized. The nonplanarity of the amide chromophore in them and its high conformational mobility, which was caused by the rotation around the N-C(O) bond, were shown on the basis of the investigation of the CD spectra and the calculations of simple models by the MNDO method. The possible correlation of the sign of the Cotton effect of the long-wave p-* transition with the intrinsic chirality of the chromophore was studied.Communication 64 in the series Asymmetric Nitrogen, for Communication 63, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 41–47, January, 1989.     

Mass spectrometry study of the kinetics of CdTe molecular-beam epitaxy: Part II. Cd, Te2, Te, and CdTe

The results of an in situ mass-spectrometric study of surface processes occurring during CdTe molecular beam epitaxy are presented. The measurements of kinetic parameters are performed with modulated Cd and Te₂ molecular beams with an intensity of 0.1–5.0 ML/s at a crystal temperature of 550–730 K. The experimental results are treated using a model in which condensation and evaporation proceed through adsorption and desorption steps. The desorption rates are 2–15 and 150 s^?1 for Te₂ and Cd, respectively. The activation energy of CdTe “evaporation” is found to be 1.2 eV; the desorption energies are E _d(Cd) = 1.0 eV and E _d(Te₂) = 0.3 eV. The adsobate coverage with cadmium atoms and tellurium molecules is estimated to be n(Cd) < 0.01, n(Te₂) = 0.02–0.20, and n(Te) = 0.2–1.0.     

A template guided approach to generating cell permeable inhibitors of Staphylococcus aureus biotin protein ligase

Inhibitors of biotin protein ligase (BPL) are novel antimicrobial compounds with the potential to treat infections caused by bacteria resistant to current antibiotics. A novel BPL inhibitor (12, K_i 1.4 μM) was synthesized from biotin acetylene and an azide-functionalized analogue of fluorescent nitrobenzofurazan by Cu(I) catalysed cycloaddition and also by template guided synthesis using wild-type BPL from Staphylococcus aureus. LC/HRMS-based detection provides improved sensitivity over previous reports using a mutant BPL, with demonstrated applicability to other BPLs. Super-imaging fluorescence microscopy demonstrated the accumulation of 12 in the cytoplasm of S. aureus, but not Escherichia coli. This novel fluorescent probe can be used to gain new insights into the mechanism of uptake, efflux and metabolism of BPL inhibitors in S. aureus.     

Convexity of Quadratic Transformations and Its Use in Control and Optimization

Quadratic transformations have the hidden convexity property which allows one to deal with them as if they were convex functions. This phenomenon was encountered in various optimization and control problems, but it was not always recognized as consequence of some general property. We present a theory on convexity and closedness of a 3D quadratic image of ⁿ, n3, which explains many disjoint known results and provides some new ones.