On studying methods for cleaning dielectric oil for impregnation of high-voltage pulse capacitors with film dielectric

Methods for cleaning commercial T-1500 dielectric oil with different adsorbents are studied. The oil is intended for impregnation of high-voltage pulse capacitors with film dielectric.     

Environmentally friendly, heterogeneous acid and base catalysis for the methylation of catechol: Chances for the control of chemo-selectivity

The properties of catalysts with (i) Brønsted-type acidity (H-mordenite and Al/P mixed oxide), (ii) Lewis-type acidity (Al trifluoride) or (iii) basic characteristics (Mg/Fe mixed oxide) were investigated in the gas-phase methylation of catechol. When methanol was used as the methylating agent, H-mordenite and AlF₃ gave high selectivities to guaiacol (the product of O-methylation) under mild reaction conditions, that is at very low catechol conversions. An increase in temperature led to the transformation of guaiacol to phenol and cresols, and to considerable catalyst deactivation. The basic catalyst Mg/Fe/O also favored an extensive degradation of guaiacol to phenol. On the mildly acidic catalyst Al/P mixed oxide a stable catalytic performance and a high selectivity to guaiacol at 40% catechol conversion were obtained. When methylformate, a more reactive methylating agent, was used with AlF₃ and Mg/Fe mixed oxide as catalysts, higher catechol conversions and slower deactivation rates could be achieved under mild reaction conditions, with a low extent of guaiacol degradation. However, methylformate rapidly decomposed when temperatures above 350 °C were used. Finally, tests were made by reacting catechol and diethoxymethane with acid catalysts, with the aim of synthesizing methylenedioxybenzene. The latter product was obtained with high selectivity, but with very low yield, due to both catalyst deactivation and decomposition of diethoxymethane.     

Strain aging of tube steels during operation of overland oil pipelines

We applied the methods of fatigue failure in pure bending and of impact toughness to investigate the tube steels 17GS, 19G, 14GN, 14KhGS, 10G2S, and Kh52 (Czechoslovakia) of oil pipelines after different service times, and we also determined the stress intensity factors and strain aging co-effecients. The article shows that with loinger service time the tube steels become embrittled: the number of load cycles to failure decreases, impact toughness drops abruptly, and the strain-aging coefficient increases. In embrittled steels fatigue cracks become more ramified than in nonaged steels. It was established that in proportion to the length of operation of oil pipelines the residual life of the tube steels decreases in consequence of the embrittlement of structurally inhomogeneous regions of the metal. It is shown that specimens with welding seams fail 2–2.5 times more rapidly; this testifies to the intense aging in structurally inhomogeneous regions.All-Union Research Institute for the Construction and Planning of Oil Pipelines (VNIISPTnefti), Ufa. Translated from Problemy Prochnosti, No. 11, pp. 125–128, November, 1989.     

Comparison of the Compaction Characterisitics of Selected Food Powders by Vibration, Tapping and Mechanical Compression

The compaction characteristics of selected powders in tapping could be described by either Sone's model or by a single term exponential equation. The Hausner ratio, i.e., the ratio between tapped and loose density, calculated by using these models was found to be a sensitive and useful indictor of the compaction mechanism in different types of tapping tests. The latter, especially where particle attrition was evident, could produce distinctly different compaction patterns. No correlation was found between these powders, Hausner's ratio, and their compressibility in mechanical compaction.     

N-Acetyl-B-D-glucosaminidase in milk and blood plasma during dry and early postpartum periods

Milk and plasma N-acetyl-B-D-glucosaminidase activity was determined for cows during the dry and early postpartum periods. Milk samples were taken from individual quarters of 12 cows from 7 d preceding dry off until calving. Weigh jar milk samples were taken daily for 28 d postpartum from 9 of the 12 cows. Somatic cell concentration was also measured in the postpartum samples. N-Acetyl-B-D-glucosaminidase activity of mammary secretions was significantly elevated in the dry period. Activity in mammary secretions was significantly higher than blood plasma concentrations during the dry period, which suggests that the enzyme present in mammary secretions comes mainly from within the gland. Milk enzyme concentrations declined sharply by 4 d postpartum and gradually declined through 28 d postpartum. Activity was still slightly elevated at 28 d postpartum as compared with normal lactation. Greater daily variability was seen with somatic cells than with N-acetyl-B-D-glucosaminidase. However, somatic cells were more responsive to clinical infections postpartum, showing significant elevations in both clinical episodes. The enzyme was elevated in one clinical case, but relatively unchanged in the other. Plasma levels were constant throughout both trials.     

An experimental superconducting magnetic system with an adjustable winding inductance and a 5 MJ energy capacity

An experimental superconducting magnetic system (MS) with an energy capacity of 5 MJ and an output power of no less than 130 MW is described. The MS winding is sectioned in the axial and radial directions. Owing to sectioning in radial direction, the MS may be used as an adjustable inductance enabling the stabilization of the amperage. The adjustable inductance may also be used as an efficient instrument for leveling the ratio of the active and reactive power in electric mains intended for different purposes (transport, energy industry, and emergency systems).     

Ultrastructure of a bio-electrolytic methanogenic/methanotrophic granular biofilm for the complete degradation of tetrachloroethylene in contaminated groundwater.

The electrolytical methanogenic/methanotrophic coupling (eMaMoC) process was tested in a laboratory-scale single-stage reactor for the treatment of tetrachloroethene (PCE)-contaminated waters. A water electrolysis cell was placed directly in the effluent recirculation loop for the supply of both O2 and H2 to the system: H2 serving as the electron donor for both carbonate reduction into CH4 and reductive dechlorination. The concurrent presence of O2 and CH4 could be used by the methanotrophs for co-metabolically oxidising the chlorinated intermediates left over by the anaerobic transformation of PCE. At a PCE inlet of 33-52 microM and a hydraulic residence time (HRT) of 5.6 days, PCE reductive dechlorination to dichloroethene (DCE) was over 95% with a maximum DCE mineralisation of 83%. Fluorescence in situ hybridisation with 16S rRNA probes related to type I and type II methanotrophic bacteria were utilised to localise the methanotrophic communities in the anaerobic/aerobic granules. It evidenced that with operational time, along with increasing oxygenation rate, methanotrophic communities were specifically colonising onto the outermost layer of the anaerobic/aerobic granule.