Sydnon-äthylene. I Stereoselektive Darstellung von Sydnon-äthylenen aus Sydnon-aldehyden

Sydnone Ethylenes. I Stereoselective Synthesis of Sydnone Ethylenes from Sydnone Aldehydes Sydnones are formylated in 4-position by the VILSMEIER -HAAK reaction. N(3)-Methyl- and N(3)-(p-Anisyl)-sydnone-(4)-carboxaldehyde react stereoselectively to sydnone ethylenes with diethyl ethoxycarbonylmethanephosphonate by HORNER reaction and with arylmethylphosphonium salts by WITTIG reaction in the presence of strong bases. In the latter case, especially in the absence of lithium cations, Z-selectivity is observed which is explained by electronic interaction between the sydnone cyclus and the aromatic substituent of the phosphine ylid in the first step of the reaction. The configuration of the obtained Z- and E-sydnone ethylenes is determined by means of ¹H-NMR- and IR-spectra.     

Shift Register Graphs and Permutation/Reset Automata

Abstract

This note completes the author's study of embedding of cascade products of permutation or reset automata in so-called shift register graphs.     

On the search for low correlated binary sequences

The construction of binary sequences with low aperiodic correlation is one of the most famous, but also one of the most challenging, problems in signal design theory. In recent decades, many approaches from different mathematical disciplines have been used to tackle the problem. This paper summarizes the known results and adds some new results on the peak correlation of extended Legendre sequences and on binary arrays.     

Sequential activation of a segmented ground pad reduces skin heating during radiofrequency tumor ablation: optimization via computational models

Radiofrequency (RF) ablation has become an accepted treatment modality for unresectable tumors. The need for larger ablation zones has resulted in increased RF generator power. Skin burns due to ground pad heating are increasingly limiting further increases in generator power, and thus, ablation zone size. We investigated a method for reducing ground pad heating in which a commercial ground pad is segmented into multiple ground electrodes, with sequential activation of ground electrode subsets. We created finite-element method computer models of a commercial ground pad (14 times 23 cm) and compared normal operation of a standard pad to sequential activation of a segmented pad (two to five separate ground electrode segments). A constant current of 1 A was applied for 12 min in all simulations. Time periods during sequential activation simulations were adjusted to keep the leading edge temperatures at each ground electrode equal. The maximum temperature using standard activation of the commercial pad was 41.7degC. For sequential activation of a segmented pad, the maximum temperature ranged from 39.3degC (five segments) to 40.9degC (two segments). Sequential activation of a segmented ground pad resulted in lower tissue temperatures. This method may reduce the incidence of ground pad burns and enable the use of higher power generators during RF tumor ablation.     

Gaschromatographische Bestimmung der h?heren Ester in Weindestillat, Weinbrand, Branntwein und Wein. II

Zusammenfassung Auf Grund der Beobachtung, daß freie Fettsäuren die Bestimmung höherer Äthylester \ bei gaschromatographischer Trennung an Carbowax 20 M stören können, wurden Reihenversuche zur Eliminierung dieser Störpartner durchgeführt. Dabei erwies sich Natriumhydrogencarbonat günstiger als Natriumcarbonat. Eine geeignete Methode zur Bestimmung der gradkettigen Äthylester der Capron- bis Stearinsäure, die auch für die Äthylester von ungesättigten C₁₆- und C₁₈-Säuren verwendet werden kann, wird angegeben.

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Determination of the ethyl esters of long chain fatty acids in wine distillate, brandy, and wine. II

Summary Free fatty acids are able to interfere the determination of the ethyl esters by gas chromatography on Carbowax 20 M. Therefore series of tests were made to remove the fatty acids. Sodium hydrogen carbonate was found to be more suitable than sodium carbonate. A method is described to determine the ethyl esters of fatty acids of caproic to stearic acid and of the unsaturated fatty acids with 16 and 18 carbon atoms.

     

A queueing model of an energy harvesting sensor node with data buffering

Battery lifetime is a key impediment to long-lasting low power sensor nodes and networks thereof. Energy harvesting—conversion of ambient energy into electrical energy—has emerged as a viable alternative to battery power. Indeed, the harvested energy mitigates the dependency on battery power and can be used to transmit data. However, unfair data delivery delay and energy expenditure among sensors remain important issues for such networks. We study performance of sensor networks with mobile sinks: a mobile sink moves towards the transmission range of the different static sensor nodes to collect their data. We propose and analyse a Markovian queueing system to study the impact of uncertainty in energy harvesting, energy expenditure, data acquisition and data transmission. In particular, the energy harvesting sensor node is described by a system with two queues, one queue corresponding to the battery and the other to the data buffer. We illustrate our approach by numerical examples which show that energy harvesting correlation considerably affects performance measures like the mean data delay and the effective data collection rate.     

激光技术在刚挠性HDI板的应用——微导通孔形成，图形成形，外型加工

概述了采用一个激光源能够加工刚性和挠性板的一种新型激光技术,PCB制造商可能采用最小的投资和提高生产率而进入HDI市场。