Sterically hindered phenols in negative ion mobility spectrometry–mass spectrometry

Negative corona discharge atmospheric pressure chemical ionization (APCI) was used to investigate phenols with varying numbers of tert‐butyl groups using ion mobility spectrometry–mass spectrometry (IMS‐MS). The main characteristic ion observed for all the phenolic compounds was the deprotonated molecule [M–H]⁻. 2‐tert‐Butylphenol showed one main mobility peak in the mass‐selected mobility spectrum of the [M–H]⁻ ion measured under nitrogen atmosphere. When air was used as a nebulizer gas an oxygen addition ion was seen in the mass spectrum and, interestingly, this new species [M–H+O]⁻ had a shorter drift time than the lighter [M–H]⁻ ion. Other phenolic compounds primarily produced two IMS peaks in the mass‐selected mobility spectra measured using the [M–H]⁻ ion. It was also observed that two isomeric compounds, 2,4‐di‐tert‐butylphenol and 2,6‐di‐tert‐butylphenol, could be separated with IMS. In addition, mobilities of various characteristic ions of 2,4,6‐trinitrotoluene were measured, since this compound was previously used as a mobility standard. The possibility of using phenolic compounds as mobility standards is also discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Generation of intense x-rays during ejection of a fast water jet from a metal channel to atmosphere

The radiation processes associated with a supersonic water jet exhausting from a narrow channel are considered. It has been found for the first time that the output of the channel and the initial portion of the jet are sources of intense X-radiation, generation of which is related to cavitation processes in the water jet bulk and subsequent excitation of shock waves. The frequency of X-radiation depends on the types of atoms on a radiating surface (for a jet, it is water; for a channel, the metal atoms on the surface) and increases with the charge of atoms. The total X-ray activity of an experimental setup in the mode of jet exhaust reaches 0.1 Ci. It is found for the first time that the impact of shock acoustic waves, which are formed in the air as a result of cavitation jets of water, on distant screens leads to the generation of a quasi-coherent directional X-ray emission from the back side of these screens. The spatial parameters of this radiation depend on the shape and cross section of the screen and the spatial characteristics of the shock wave.     

Magnetooptical visualization of stray magnetic fields of sample rocks using magnetouniaxial garnet ferrite film

The stray magnetic fields of rock samples with inclusions of the magnetic grains and magnetic crystals were observed using epitaxial (Bi,Lu)₃(Fe,Ga)₅O₁₂ films with uniaxial magnetic anisotropy. Basalt rocks with inclusions of titano-magnetite and native elsen but also crystals of titano-magnetite and pyrrhotin were investigated. Stray magnetic fields were visualized with the Faraday Effect.     

Calculating the chemical potential of components of a binary solution in a plane-parallel pore

The chemical potential of components of a binary solution is calculated using the expansion of the external field potential in a Taylor series. An expansion of the chemical potential in terms of concentration-concentration direct correlation functions of all orders is obtained. For a plane-parallel pore with an exponential near-wall potential, a solution to the obtained differential equation is constructed in the smooth-inhomogeneity approximation.     

Determination of parameters of elements and coupling architecture in ensembles of coupled time-delay systems from their time series

We propose a method for reconstructing model differential equations with time delay for ensembles of coupled time-delay systems from their time series. The method has made it possible to recover the parameters of elements of the ensemble as well as the architecture and strength of couplings in ensembles of nonidentical systems with delay with an arbitrary number of unidirectional and bidirectional couplings between them. The effectiveness of the method is demonstrated for chaotic and periodic time series of model equations for ensembles of diffusively coupled systems with time delay in the presence of noise, as well as experimental time series for resistively coupled radiotechnical oscillators with delayed feedback.     

Effect of thermal expansion on the heat transfer in hexafluoroethane β-C2F6

Physics of the Solid State - The thermal conductivity of solid hexafluoroethane C2F6 has been investigated by the plane-layer steady-state method under saturated vapor pressure at temperatures...     

Optical absorption in cobalt-containing single-crystal epitaxial films of gadolinium gallium garnets

Cobalt-containing single-crystal garnet films are grown by liquid-phase epitaxy from supercooled PbO-B₂O₃-and Bi₂O₃-B₂O₃-based solution melts on Gd₃Ga₅O₁₂ substrates. It is shown that cobalt in the films is in a trivalent state. Upon introduction of GeO₂ into the initial solution melt, cobalt transforms into a bivalent state. It is revealed that the absorption spectrum of the grown films exhibits two broad bands in the wavelength ranges 450–800 and 900–1800 nm. Each of these bands contains three components. The spin-orbit splitting of the observed bands is determined.     

Non-local symmetries of first-order equations

It is shown how one can transform scalar first-order ordinarydifferential equations which admit non-local symmetries of theexponential type to integrable equations admitting canonicalexponential non-local symmetries. As examples we invoke theAbel equation of the second kind, the Riccati equation and naturalgeneralizations of these. Moreover, our method describes howa double reduction of order for a second-order ordinary differentialequation which admits a two-dimensional Lie algebra of generatorsof point symmetries can be affected if the second-order equationis first reduced in order once by a symmetry which does notspan an ideal of the two-dimensional Lie algebra.     

Thermal properties of mixed-ligand magnesium complexes with beta-diketonates and diamimes as potential MOCVD precursors

The series of adducts of magnesium beta-diketonates with diamimes namely Mg(thd)₂(tmeda) 1 and four new complexes Mg(thd)₂(tmpda) 2, Mg(thd)₂(pda) 3, Mg(ptac)₂(tmeda) 4, Mg(tfac)₂(tmeda) 5 [beta-diketonates = R₁C(O)CHC(O)R₂: thd (R₁ = R₂ =  ^t Bu), ptac (R₁ =  ^t Bu, R₂ = CF₃), tfac (R₁ = Me, R₂ = CF₃); diamines = R₂N(CH₂) _n NR₂: tmeda (n = 2, R = Me), tmpda (n = 3, R = Me), pda (n = 3, R = H)] were synthesized in order to investigate the influence of both ligand types on the thermochemical properties of these compounds. The thermal behavior of the complexes in the condensed phase was investigated by thermogravimetry and differential scanning calorimetry; the thermodynamic parameters of phase transitions were determined. The saturated vapor pressure of solid complexes Mg(thd)₂(tmeda) and Mg(tfac)₂(tmeda) were measured by the transmission method giving the enthalpies and entropies of sublimation processes. The reliable thermodynamic data for compound Mg(thd)₂(tmeda) were obtained with the assistance of X-ray diffraction and the static method of saturated and unsaturated vapor pressure measurements.