Investigation of a correlation fiber-optic ring interferometer based on a multimode optical fiber

Khar'kov Institute of Radio Electronics. Translated from Izvestiya Vysshykh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 5, pp. 607–610, May, 1991.     

Applicability of the critical chromatography concept to proteomics problems: Dependence of retention time on the sequence of amino acids

A peptide separation model based on the technique of liquid chromatography of macromolecules at the critical condition was proposed. In terms of this model, the array of experimental data on the separation of peptides is considered. The main phenomenological parameters of the model—effective adsorption energies of amino acid residues—were determined, thus allowing the influence of character of their alternation in the chain on retention times to be predicted. The model is applicable to investigation into the feasibility of separation in different chromatographic modes of not only peptides with the same amino acid composition and different sequences of units in the chain but also peptides containing amino acid isomers and mirror sequences with different terminal groups.     

Stability of liquid-metal ion sources

In this paper we find the parameters (radii, lengths, velocities) of the jets produced in liquid-metal ion sources. The jet stability with respect to developing sausages (Rayleigh instability) is studied. The Rayleight instability is shown to occur for rather large currents (in long jets). The currents critical for the instability initiation are calculated for Ga and Au sources. The results are in accordance with the experimental data available. In the case of Ga, the accordance is achieved only for the hot jet model (TT _m , whereT _m is the melting temperature), when the viscosity is appreciably lower.     

A chemical investigation ofMatteuccia struthiopteris

Irkutsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 608–609, July–August, 1993.     

Simple Concentration Boundaries and Their Role in the Formation of a Stationary Ionic Boundary in Isotachophoresis

It is shown that processes that are associated with the formation or non-formation of a concentration boundary during isotachophoresis substantially affect the terminator adjustment to a steady-state concentration.     

A novel high-performance fourier transform ion cyclotron resonance cell for improved biopolymer characterization

A new trapped ion cell design for use with Fourier transform ion cyclotron resonance mass spectrometry is described. The design employs 15 cylindrical ring electrodes to generate trapping potential wells and 32 separately assignable rod electrodes for excitation and detection. The rod electrodes are positioned internal to the ring electrodes and provide excitation fields that are thereby linearized along the magnetic field over the entire trapped ion volume. The new design also affords flexibility in the shaping of the trapping field using the 15 ring electrodes. Many different trapping well shapes can be generated by applying different voltages to the individual ring electrodes, ranging from quadratic to linearly ramped along the magnetic field axis, to a shape that is nearly flat over the entire trap volume, but rises very steeply near the ends of the trap. This feature should be useful for trapping larger ion populations and extension of the useful range of ion manipulation and dissociation experiments since the number of stages of ion manipulation or dissociation is limited in practice by the initial trapped ion population size. Predicted trapping well shapes for two different ring electrode configurations are presented, and these and several other possible configurations are discussed, as are the predicted excitation fields based on the use of rod electrodes internal to the trapping ring electrodes. Initial results are presented from an implementation of the design using a 3.5 T superconducting magnet. It was found that ions can be successfully trapped and detected with this cell design and that selected ion accumulation can be performed with the utilization of four rods for quadrupolar excitation. The initial results presented here illustrate the feasibility of this cell design and demonstrate differences in observed performance based upon different trapping well shapes.     

Electrophysical characteristics and stability of solid apatite-like electrolytes La x Si6O12 + 1.5x and La x Ge6O12 + 1.5x

Oxygen-ion conduction in apatite-like compounds based on silicates and germanates of lanthanum La _x A₆O_{12 + 1.5x} (A = Si, Ge; x = 9.11–10.22) is studied. The compounds are shown to be purely ionic conductors at 600–900°C and partial oxygen pressures 10^?16 to 10⁵ Pa. The electroconductivity of the best conducting specimens of La _x A₆O_{12 + 1.5x} (A = Si, Ge; x = 9.77–10) exceeds that of electrolyte YSZ at moderate temperatures. The electroconductivity of lanthanum germanate is substantially greater than that of lanthanum silicate, specifically, 7.85 × 10^?2 and 2.35 × 10^?2 S cm^?1, respectively, at 800°C. An inflection is discovered at ～750°C in the temperature dependences of electroconductivity of La _x Ge₆O_{12 + 1.5x} (x = 9.77–10.22). A dilatometric examination points to a second-kind phase transition that may be due to the oxygen sublattice disordering. The behavior of apatite-like electrolytes La _x A₆O_{12 + 1.5x} (A = Si, Ge) during long exploitation periods in the interval of working temperatures of electrochemical devices is studied for the first time ever. The electrolytes’ aging at 800°C in air for 1000 h was investigated by the electroconductivity method. The electroconductivity of lanthanum germanates decayed with time by 5% and that of lanthanum silicates, by 9.5%. The steady-state values of electroconductivity of all compounds studied is reached after 600–700 h. The compounds studied form a class of materials that hold some promise as solid electrolytes for medium-temperature fuel cells and other electrochemical devices.     

Analysis of functionality-type distributions as a method for studying the kinetics of chemical reactions involving reactive oligomers

Critical chromatography is used to study the kinetics of reactions between polypropylene glycols and phenyl butyl isocyanate that simulate the production of polyester urethanes. The use of a two-detector version of chromatography makes it possible to monitor the concentration of the original, intermediate, and final oligomers and reveal the effect of one end group on the reactivity of the other separated by a long chain. The processing of the kinetic data makes it possible to determine the reaction-rate constants for macromolecules of different functionalities and to quantitatively describe the process behavior.