Fragmentation and Isomerization Due to Field Heating in Traveling Wave Ion Mobility Spectrometry

During their travel inside a traveling wave ion mobility cell (TW IMS), ions are susceptible to heating because of the presence of high intensity electric fields. Here, we report effective temperatures T _eff,vib obtained at the injection and inside the mobility cell of a SYNAPT G2 HDMS spectrometer for different probe ions: benzylpyridinium ions and leucine enkephalin. Using standard parameter sets, we obtained a temperature of ~800 K at injection and 728?±?2 K into the IMS cell for p-methoxybenzylpyridinium. We found that T _eff,vib inside the cell was dependent on the separation parameters and on the nature of the analyte. While the mean energy of the Boltzmann distributions increases with ion size, the corresponding temperature decreases because of increasing numbers of vibrational normal modes. We also investigated conformational rearrangements of 7+ ions of cytochrome c and reveal isomerization of the most compact structure, therefore highlighting the effects of weak heating on the gas-phase structure of biologically relevant ions.

Production and Characterization of β-Glucanase Secreted by the Yeast Kluyveromyces marxianus

An extracellular β-glucanase secreted by Kluyveromyces marxianus was identified for the first time. The optimal conditions for the production of this enzyme were evaluated by response surface methodology. The optimal conditions to produce β-glucanase were a glucose concentration of 4 % (w/v), a pH of 5.5, and an incubation temperature of 35 °C. Response surface methodology was also used to determine the pH and temperature required for the optimal enzymatic activity. The highest enzyme activity was obtained at a pH of 5.5 and a temperature of 55 °C. Furthermore, the enzyme was partially purified and sequenced, and its specificity for different substrates was evaluated. The results suggest that the enzyme is an endo-β-1,3(4)-glucanase. After optimizing the conditions for β-glucanase production, the culture supernatant was found to be effective in digesting the cell wall of the yeast Saccharomyces cerevisiae, showing the great potential of β-glucanase in the biotechnological production of soluble β-glucan.     

Structure and properties of copper coatings electrodeposited under X-ray radiation

142-145The influence of X-ray radiation of different wave lengths on the structure and properties of electrodeposited copper coatings is found. It is determined by the methods of X-ray structure analysis and optical and scanning microscopy that, in the process of electrodeposition, X-ray radiation changes the primary structure of electrolyte and leads to a decrease in the grain size of deposits and an increase in the microhardness and degree of dispersion of mosaic blocks. The radiation effect on the process of electrodeposition is accompanied by an increase in the rate of material deposition on the cathode due to intensification of the diffusion of electrolyte components to the cathode.     

Effects of electron inelastic transport through the potential relief of a spin dimer in a magnetic field

The influence of inelastic effects on electron quantum transport through the potential relief of a dimer system was studied by exact solution of the Schrodinger equation. The nature of this problem is due to the coherent superposition of the different potential profiles through which the spin-polarized electron tunnels. It was found that the low magnetic field initiates new peaks of resonant tunneling. In high magnetic fields, the transport of electrons with opposite spin polarization is qualitatively different.     

A study of structuring of a microdisperse filler in oligomer formulations in a flow

Method for analysis of the evolution of microstructural formations of a disperse filler in transparent oligomer formulations in a flow is suggested. The method enables studies of microstructural changes in formulations in a wide range of viscosities, temperatures of the medium, shear stresses, and filler dispersities.     

Influence of nonlinear effects on destruction of active elements of electron-beam-pumped lasers Based on ZnSe-containing quantum-size structures

The fracture patterns of active elements of pulsed green lasers with transverse electron-beam pumping, based on ZnSe-containing quantum-size structures, have been investigated. The fracture in the form of thin (～1 μm) and long (to 100–150 μm) filaments can be explained by the self-focusing of the intrinsic laser radiation in the semiconductor structure.     

Characteristic electron loss spectra and electronic structure of thallium chloride

The bands, state densities N(E), and permittivity are theoretically found for TlCl crystals. On the basis of the experimental characteristic electron loss spectra, the spectra of the complete set of optical functions including permittivity and bulk electron loss spectra are calculated and decomposed into components. The obtained data are compared with the well-known theoretical results. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 8–11, June, 2008.     

The specific contribution of phosphorus in dendrimer chemistry

Besides properties commonly found for all types of dendrimers, phosphorus-containing dendrimers possess some specific properties seldom or never found for other types of dendrimers. Emphasis will be put on these specificities.