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21.
Dielectric studies are presented of a banana-shaped compound that exhibits the antiferroelectric B2 phase. Upon application and subsequent removal of strong electric fields the textures and dielectric properties of the phase drastically change. Most notable is the huge increase of the low frequency permittivity. This behaviour would suggest the induction of ferroelectricity by the electric field. 相似文献
22.
23.
A. Saxena D. Fabris G. Prete D. V. Shetty G. Viesti B. K. Nayak D. C. Biswas R. K. Choudhury S. S. Kapoor M. Lunardon S. Moretto G. Nebbia S. Pesente V. Rizzi A. M. Samant M. Barbui E. Fioretto M. Cinausero A. Brondi G. La Rana R. Moro E. Vardaci N. Gelli F. Lucarelli 《Nuclear Physics A》2004,730(3-4):299-315
Pre-scission and post-scission multiplicities of neutrons and alpha particles have been simultaneously measured for the fission-like reactions of 340 MeV 28Si on 232Th. Dynamical model calculations using HICOL code predict that about 90% of the observed events are of quasi-fission type while the remaining 10% are from compound nucleus fission decay. Moving source fits were carried out to the observed neutron and alpha particle spectra, measured at different angles with respect to the fragment directions. The pre-scission and post-scission neutron multiplicities are deduced to be 8.7±2.0 and 9.4±2.0, respectively. The corresponding multiplicity values for alpha particles are found to be 0.22±0.08 and 0.1±0.03. From the measured post-scission neutron multiplicity, it is inferred that about 65±20 MeV of the initial excitation energy remains at scission. This may be compared to the value of 85±30 MeV estimated from PACE2 statistical model calculations, adjusted to reproduce the measured pre-scission neutron multiplicity. From a comparison of the Statistical Model predictions with the measured pre-scission neutron multiplicity, the fission delay is estimated to be of 5+7−3×10−20 s which overlaps with the average duration of fission-like process from the contact to the scission point (2×10−20 s) as determined from HICOL-based dynamical calculations. For the delay time deduced as above, the pre-scission alpha particle multiplicity calculated by the PACE2 code is about a factor two larger than the experimental one, demonstrating the difficulties in modelling the alpha particle emission from highly elongated shapes that characterize the fissioning system from the contact point to scission. 相似文献
24.
Prof. Guido Barone Prof. Aldo La Ginestra 《Journal of Thermal Analysis and Calorimetry》1992,38(12):2563-2563
25.
A novel approach to H-phosphonates from hypophosphorous acid using a transfer hydrogenation process was developed. This method is atom-economical, environmentally friendly, catalytic, and efficient, leading easily to H-phosphonate monoesters or ammonium salt in moderate to good yields. 相似文献
26.
Andrea Lodi Monica Caselli Alessandro Casnati Fabio Momicchioli Francesco Sansone Davide Vanossi Glauco Ponterini 《Journal of Molecular Structure》2007,846(1-3):49-54
The sulfonated calixarene I8C12 acts as a host for homologous merocyanines Mc1 and Mc2 in organic solvents, exhibiting neither selectivity towards the guest dyes nor solvent dependence of the complexation equilibria. In water, on the contrary, only the lower homologue, Mc1, is solubilized in the presence of the calixarene. A combination of UV–visible and fluorescence spectroscopic and photophysical analysis and MD structural simulation of the calixarene-dye complexes was employed to account for the observations, and suggests that a radical change in the complexation mode occurs upon moving from an organic to an aqueous environment. 相似文献
27.
V. N. Manuilov T. Idehara M. Kamada T. Hayashi La Agusu T. Kanemaki K. Yatsui Wiehua Jiang 《International Journal of Infrared and Millimeter Waves》2006,27(9):1183-1193
High power Large Orbit Gyrotron (LOG) [1] is now under development at FIR FU. First version of this device was recently manufactured
and then assembled with power supply ETIGO-IV [2]. Results of preliminary tests of electron-optic system are presented. The
conditions when stableflat form of current pulse realized are discussed. Analytical estimations of cathode-anode distance
to achieve small influence of cathode plasma during high voltage (HV) pulse are performed.
Two new electron gun versions with decreased influence of the cathode plasma on its impedance and pulse form are suggested
and optimized. New optimal magnetic field distributions are found. First gun has quiasi-flat cathode configuration near the
anode diaphragm and provides operating current about 60 A. Second one uses blade cathode with operating current about 30 A.
Beam quality for both guns is suitable for LOG operation. 相似文献
28.
J. Lí nares M. V. P Rez R. E. La Fuente X. Prieto C. Montero L. Gato J. I. Rodriguez C. G mez-Reino 《Fiber and Integrated Optics》1993,12(3):231-245
An experimental analysis of graded-index (GRIN) planar waveguides produced by ion exchange in soda-lime glass is presented. This study is based on a recent model describing nonlinear diffusion. Likewise the modal coupling between planar waveguides, produced in the same substrate, is analyzed in order to design efficient integrated optical components. Finally, waveguiding structures induced by Kerr effect in glass are proposed and analyzed. 相似文献
29.
An automatic continuous-flow photometric method for the determination of ammonia is proposed. It is based on the Berthelot reaction, the product of which is temporarily immobilized on a suitable support (Sephadex QAE) located in the flow-cell. The retained product is eluted after measurement by a cationic surfactant contained in the carrier solution. The method allows the determination of the analyte between 0.4 and 20.0 gmg/ml, with an RSD of 0.8%, at a sampling frequency of 13/hr. The determination limit can be reduced by a factor of ten by using a flow-cell with a two-fold longer path length, but the sampling frequency is also reduced as a result. The method was applied to the determination of this analyte in agricultural samples (plants and soils) and compared with standard methods for these types of samples. 相似文献
30.