912 resultados para Substitution of Components
Resumo:
"10 March 1981."
Resumo:
"31 March 1981."
Resumo:
"October 1981."
Resumo:
"1 October 1980."
Resumo:
"November 1989."
Resumo:
"March 1981."
Resumo:
"May 1983."
Resumo:
In ionic liquids [Bmim][PF6] or [Bmim][BF4], pyrrole replaced the halogen atom of an alkyl halide to give the corresponding N-substituted pyrrole in excellent yield. Benzenesulfonyl chloride, p-methylbenzenesulfonyl chloride and benzoyl chloride reacted similarly with pyrroles to afford the N-substituted pyrroles in quantitative yield. Michael addition reaction of pyrrole with electrophilic olefins was completed in a highly regioselective manner to afford the N-alkylpyrroles.
Resumo:
A sudden change applied to a single component can cause its segregation from an ongoing complex tone as a pure-tone-like percept. Three experiments examined whether such pure-tone-like percepts are organized into streams by extending the research of Bregman and Rudnicky (1975). Those authors found that listeners struggled to identify the presentation order of 2 pure-tone targets of different frequency when they were flanked by 2 lower frequency “distractors.” Adding a series of matched-frequency “captor” tones, however, improved performance by pulling the distractors into a separate stream from the targets. In the current study, sequences of discrete pure tones were substituted by sequences of brief changes applied to an otherwise constant 1.2-s complex tone. Pure-tone-like percepts were evoked by applying 6-dB increments to individual components of a complex comprising harmonics 1–7 of 300 Hz (Experiment 1) or 0.5-ms changes in interaural time difference to individual components of a log-spaced complex (range 160–905 Hz; Experiment 2). Results were consistent with the earlier study, providing clear evidence that pure-tone-like percepts are organized into streams. Experiment 3 adapted Experiment 1 by presenting a global amplitude increment either synchronous with, or just after, the last captor prior to the 1st distractor. In the former case, for which there was no pure-tone-like percept corresponding to that captor, the captor sequence did not aid performance to the same extent as previously. It is concluded that this change to the captor-tone stream partially resets the stream-formation process, and so the distractors and targets became likely to integrate once more. (PsycINFO Database Record (c) 2011 APA, all rights reserved)
Resumo:
Two ways to improve efficiency of components based on Talbot effect are considered in the present paper. One way is based on optimization of waveguide wall impedance, another one consists in modification of waveguide cross-section shape. Both methods allow correction of waveguide modes spectrum and lead to efficiency enhancement. For the important application of Talbot effect-remote steering antenna of a wavebeam in plasma-the steering band is expanded by 40-50%. © 2007 Springer Science+Business Media, LLC.
Resumo:
Two ways to increase efficiency of components based on Talbot effect are considered: optimization of waveguide wall impedance and corrections of waveguide cross-section. It is shown that for many cases undesired scattering losses can be made several times less than that for usual cases of infinite of zero impedance and rectangular waveguide cross-section.
Resumo:
Cigarette smoke is a complex mixture of more than 4000 hazardous chemicals including the carcinogenic benzopyrenes. Nicotine, the most potent component of tobacco, is responsible for the addictive nature of cigarettes and is a major component of e-cigarette cartridges. Our study aims to investigate the toxicity of nicotine with special emphasis on the replacement of animals. Furthermore, we intend to study the effect of nicotine, cigarette smoke and e-cigarette vapours on human airways. In our current work, the BEAS 2B human bronchial epithelial cell line was used to analyse the effect of nicotine in isolation, on cell viability. Concentrations of nicotine from 1.1µM to 75µM were added to 5x105 cells per well in a 96 well plate and incubated for 24 hours. Cell titre blue results showed that all the nicotine treated cells were more metabolically active than the control wells (cells alone). These data indicate that, under these conditions, nicotine does not affect cell viability and in fact, suggests that there is a stimulatory effect of nicotine on metabolism. We are now furthering this finding by investigating the pro-inflammatory response of these cells to nicotine by measuring cytokine secretion via ELISA. Further work includes analysing nicotine exposure at different time points and on other epithelial cells lines like Calu-3.
