General purpose centrifugal compressor 32VTs-100/9

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 4, pp. 14–15, April, 1989.     

A Device for Measurements of Dielectric Characteristics of Liquid Crystalline Materials, Solid Substances, and Their Melts

The device developed allows one to measure the dielectric characteristics of solid substances and their melts at frequencies of 20–20000 Hz and in a wide temperature range of 20–250°C. The measured temperature dependencies of the dielectric permittivities of several molecular and liquid crystals (stilbene, diphenyl, naphthalene, cholesterylpelargonate, and 8OCB) are presented.     

Extended analysis of ground impedance measurement using the fall-of-potential method

An extended analysis of ground impedance measurement using the fall-of-potential method will be presented. An interesting curve that represents the exact locations of the potential probe when the potential and current probes are in different directions is obtained for the first time. Curves representing measurement error are also presented for the case when the potential probe is placed in locations where the correct ground impedance cannot be measured. A similar analysis for ground impedance measurements in multilayer soils is also discussed. The study presented in this paper has extended the theory of the conventional fall-of-potential method and the results obtained can serve as a practical guide for ground impedance measurements made using this method.     

Subkilohertz fluctuations and mode hopping in high-powergrating-stabilized 980-nm pumps

The behavior of fiber Bragg grating (FBG)-stabilized 980-nm pump lasers is experimentally and theoretically investigated. The subkilohertz noise in the emitted power is related to the coexistence and oscillation between coherence collapsed state and narrow linewidth single-mode (SM) operation. These findings are theoretically discussed by using a multimode time-domain model that accounts for spatial harmonics and includes nonlinear gain. One additional result is an indication that kinks in the L-I curve can be explained by nonlinear mode competition     

RF Reference Signal Transport by Optical Fibers

Among the various applications of optical fibers, the transmission of time or frequency reference signals seems to have some interest in view of the immunity of the fibers from electromagnetic disturbances. An analysis of the possible causes of phase fluctuation in a link and a feasibility test for the transmission of a local oscillator signal in a receiving system are reported.     

Cyclic variations in the permeability of the cell wall of Saccharomyces cerevisiae.

To study cell-cycle-related variations in wall permeability of Saccharomyces cerevisiae, two approaches were used. First, an asynchronous culture was fractionated by centrifugal elutriation into subpopulations containing cells of increasing size. The subpopulations represented different stages of the cell cycle as judged by light microscopy. Cell wall porosity increased when these subpopulations became enriched with budded cells. Secondly, synchronous cultures were obtained by releasing MATa cells from alpha-factor induced G1-arrest. These cultures grew synchronously for at least two generations. The cell wall porosity increased sharply in these cultures, shortly before buds became visible and was maximal during the initial stages of bud growth. It decreased in cells which had completed nuclear migration and before abscission of the bud had occurred. The porosity reached its lowest value during abscission and in unbudded cells. We examined the incorporation of mannoproteins into the wall during the cell cycle. SDS-extractable mannoproteins were incorporated continuously. However, the incorporation of glucanase-extractable mannoproteins, which are known to affect cell wall porosity, showed cyclic oscillations and reached its maximum after nuclear migration. This coincided with a rapid decrease in cell wall porosity, indicating that glucanase-extractable mannoproteins might contribute to this decrease.