Improved procedures have been proposed for fast and selective hydrogenation of aromatic nitro compounds with the goal of obtaining practically important amines.
Application of time-variable feedback to the input amplifier of pulse magnetic resonance spectrometers: Experimental studies
摘要:
Experimental research on the improvement of the sensitivity and time resolution of pulsed magnetic resonance spectrometers is discussed. It is shown that application of a time-variable feedback of a signal to the input of the receiver amplifier can decouple the "fixed" relationship between the quality factor Q and the ringdown time of the resonance system. Experiments were performed with low-frequency, radio-frequency and microwave pulse-type magnetic resonance receivers. Modifications of an S/C-band electron spin echo modulation spectrometer carried out to check the "time-variable feedback" performance are described. It is demonstrated that the application of a time-variable feedback can significantly reduce the ringdown time and improve the recovery properties of the magnetic resonance receiver system. It is also demonstrated that the time-variable feedback can improve the overall receiver sensitivity due to the fact that the working bandwidth of the resonance system can be optimized separately for the transmitting and the receiving mode. Signal values could be increased at least three times and the signal-to-noise ratio about 1.5-2 times. The largest improvement is achieved with the initially overcoupled resonator. Experimental spectra of test samples for different settings of the time-variable feedback are shown.
Substitution controlled aryne insertion: synthesis of diarylmethane/chromones
作者:Jadhav Rahul Dhanaji、Polasani Samatha、Silver Raju、Prathama S. Mainkar、Raju Adepu、Srivari Chandrasekhar
DOI:10.1039/d2cc05992d
日期:——
Aryne insertion reaction with 2-aroyl malonates/cyanoesters lead to the formation of diarylmethane or chromones depending on the substitution on the aryne ring. The presence of an electronegative atom at the ortho position of arynes generates chromones, whereas other arynes lead to the formation of diarylmethanes, via a cascade double aryne insertion.
Dornow; Fust, Chemische Berichte, 1954, vol. 87, p. 985,989
作者:Dornow、Fust
DOI:——
日期:——
Application of time-variable feedback to the input amplifier of pulse magnetic resonance spectrometers: Experimental studies
作者:A. V. Koptioug、E. J. Reijerse、A. A. K. Klaassen
DOI:10.1007/bf03166126
日期:2002.12
Experimental research on the improvement of the sensitivity and time resolution of pulsed magnetic resonance spectrometers is discussed. It is shown that application of a time-variable feedback of a signal to the input of the receiver amplifier can decouple the "fixed" relationship between the quality factor Q and the ringdown time of the resonance system. Experiments were performed with low-frequency, radio-frequency and microwave pulse-type magnetic resonance receivers. Modifications of an S/C-band electron spin echo modulation spectrometer carried out to check the "time-variable feedback" performance are described. It is demonstrated that the application of a time-variable feedback can significantly reduce the ringdown time and improve the recovery properties of the magnetic resonance receiver system. It is also demonstrated that the time-variable feedback can improve the overall receiver sensitivity due to the fact that the working bandwidth of the resonance system can be optimized separately for the transmitting and the receiving mode. Signal values could be increased at least three times and the signal-to-noise ratio about 1.5-2 times. The largest improvement is achieved with the initially overcoupled resonator. Experimental spectra of test samples for different settings of the time-variable feedback are shown.