Mathematical modeling of random coupling between polarization modes in single-mode optical fibers: XIII. Conditions of applicability of the ergodic hypothesis for fiber ring interferometers

Some additional conditions of applicability of the ergodic hypothesis to fiber ring interferometers (FRIs) with a loop consisting of a single-mode optical fiber (SMOF) with random inhomogeneities are considered. It is shown by mathematical modeling that the change in the phase difference of counterpropagating waves at the FRI output with the SMOF temperature is not a stationary random process. However, in a fairly narrow temperature range, this dependence can be assumed to be locally stationary. The conditions determining this temperature range are formulated. It is shown for a fairly large ensemble of independent realizations of random inhomogeneities in an SMOF that, even when all conditions of ergodicity are satisfied with a large margin, there will always be at least one realization violating strict ergodicity. Thus, only conditional (approximate) ergodicity occurs in this case. Nevertheless, in calculation of the FRI zero drift in this situation, averaging over an ensemble of independent realizations of random inhomogeneities in the SMOF of an FRI loop can be performed with sufficient accuracy. As a result, calculations are simplified significantly. In the general case, when at least one of the conditions of ergodicity is not satisfied, averaging over temperature for each realization with subsequent averaging over the entire ensemble should be performed. It is shown also that, within this problem, we can speak only about quasi-ergodicity or emulation of ergodicity, since a change in the temperature of the SMOF of an FRI loop and successive enumeration of independent realizations of random inhomogeneities in the SMOF loop are radically different random processes. The parameters characterizing quasiperiodic temperature changes in the phase difference of counterpropagating waves at the FRI output are refined.     

Application of size exclusion chromatography to the structural study of polyorganometallosiloxanes

Size exclusion chromatography was employed to elucidate the structure of the organosiloxane moiety in trimethylsiloxy derivatives of organometallosiloxanes containing Na, K, Ni, Mn, Cu, and Fe. An efficient technique of trimethylsilylation of organometallosiloxanes was developed to minimize alterations in their structure. The TMS derivatives of organometallosiloxanes were found to exist mostly as a more or less polydisperse mixture of cyclic poly[phenyltrimethylsiloxy siloxane]s. The preferred size of the cycles depends primarily on the nature of the metal in organometallosiloxane.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1057–1062, June, 1994.This work was performed with the financial support of the Russian Foundation for Basic Research (Grant No. 93-03-18121).     

The Maraner effect as a particular case of the quadratic Sagnac effect

Optics and Spectroscopy - The quadratic Sagnac effect consists in a Michelson interferometer (MI) being located on a rotating base with a phase difference in its arms arising, the value of which...     

Aerodynamic levitation and laser heating:

Aerodynamic levitation is an effective way to suspend samples which can be heated with CO₂ lasers. The advantages of this containerless technique are the simplicity and compactness of the device, making it possible to integrate it easily in different kinds of experiments. In addition, all types of materials can be used, including metals and oxides. The integration of aerodynamic levitation at synchrotron and neutron sources provides powerful tools to study the structure and dynamics of molten materials. We present here an overview of the existing techniques and of the developments made at the CEMHTI in Orléans, as well as a few examples of experimental results already obtained.     

Applications of nanodiamonds for separation and purification of proteins

Recombinant apoobelin and recombinant luciferase are separated from bacterial cells of Escherichia coli with the use of detonation nanodiamonds. The application of nanodiamonds has a number of points in its favor, namely, (i) simplifies the procedures for purifying the proteins, (ii) decreases the time of their separation to 30–40 min, (iii) eliminates the necessity of using special chromatographic equipment, and (iv) makes it possible to prepare high-purity apoobelin and luciferase materials with protein yields of 35–45 and 45–60%, respectively. The possible mechanisms of interaction of protein molecules and nanodiamond particles are analyzed.     

Production of a humanized Fab fragment of a neutralizing antibody against rabies virus

This paper describes the production of a functional humanized Fab fragment of a neutralizing antibody against the rabies virus. It is a prototype of a therapeutic agent that could be an alternative to equine anti-rabies immunoglobulins and anti-rabies serum immunoglobulins obtained from the blood of vaccinated human donors. Variable fragments of the high-affinity light and heavy chains neutralizing an antibody against the rabies virus were cloned and sequenced. Mouse constant regions were replaced by human constant regions followed by expression of the humanized Fab fragments in a yeast expression system. The immunochemical properties of the Fab fragments were evaluated using ELISA, polyacrylamide gel electrophoresis, and the Western blot assay. The binding capability of the produced humanized Fab fragments surpasses that of the parental antibody. A high degree of humanization was confirmed using sera against human immunoglobulins. The yield of the humanized Fab fragments was 21 mg per liter of culture medium. The purified Fab fragment preparation did not contain traces of the isolated light and heavy chains of the humanized Fab fragments.     

Selective extraction-photometric redox determination of low concentrations of sulfur(IV), selenium(IV), tellurium(IV), and arsenic(III)

A procedure is proposed for the selective extraction-photometric determination of the acid-forming elements S(IV), Se(IV), Te(IV), and As(III) in their mixtures containing molecular forms or anions with different electron densities on donor atoms. The procedure is based on the difference in the oxidizability of analytes with the [SbCl₆]^? complex. The analytical ranges are found at different pHs of the medium, affecting the potential of the two-phase redox systems. The detection limits for sulfite, selenite, tellurite, and arsenite are 1 × 10^?3, 5 × 10^?5, 7 × 10^?5, and 1 μg/mL, respectively. The procedure is applied to the determination of selenium in H₂SO₄ of high-purity grade, which is used in the production of microelectronics items and in some agricultural samples. The error of analysis is no worse than 20%.     

Mathematical modeling of random coupling between polarization modes in single-mode optical fibers: XII. Dependence of the zero drift in fiber ring interferometers in orthogonal polarization modes on the range of temperature variation in an optical fiber

Temperature dependences of the zero drift in a fiber ring interferometer (FRI) without a polarizer in the presence of random inhomogeneities in a single-mode optical fiber in the FRI loop are obtained by numerical simulation. The results are compared with known experimental data. It is shown that FRIs using a superluminescent diode as a source of nonmonochromatic radiation and a loop made of a single-mode optical fiber with weak linear birefringence can find application as low-accuracy fiber-optic gyroscopes and FRIs with a loop made of a single-mode optical fiber with strong linear birefringence can be used as medium-accuracy fiber-optic gyroscopes.