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111.
Nilson PM Willingale L Kaluza MC Kamperidis C Minardi S Wei MS Fernandes P Notley M Bandyopadhyay S Sherlock M Kingham RJ Tatarakis M Najmudin Z Rozmus W Evans RG Haines MG Dangor AE Krushelnick K 《Physical review letters》2006,97(25):255001
We present measurements of a magnetic reconnection in a plasma created by two laser beams (1 ns pulse duration, 1 x 10(15) W cm(-2)) focused in close proximity on a planar solid target. Simultaneous optical probing and proton grid deflectometry reveal two high velocity, collimated outflowing jets and 0.7-1.3 MG magnetic fields at the focal spot edges. Thomson scattering measurements from the reconnection layer are consistent with high electron temperatures in this region. 相似文献
112.
Predicting solvent effects in ionic liquids: Extension of a nucleophilic aromatic substitution reaction on a benzene to a pyridine
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Rebecca R. Hawker Ronald S. Haines Jason B. Harper 《Journal of Physical Organic Chemistry》2018,31(10)
A nucleophilic aromatic substitution reaction involving a halopyridine electrophile was examined in a series of ionic liquid solvents. This reaction was chosen to test the known solvent effects of ionic liquids on this type of reaction mechanism, previously described with a halobenzene electrophile. The effect of varying the proportion of the ionic liquid in solution was determined, and it was shown that the more ionic liquid present in the reaction mixture, the greater the rate constant enhancement. Temperature‐dependent kinetic analyses yielded activation parameters that showed that the rate constant enhancements are controlled by a balance between enthalpic and entropic effects, depending upon the proportion of ionic liquid present. Overall, the rate enhancement is entropically driven, due to organisation of the ionic liquid about the electrophile. These results are consistent with what has been observed previously for the nucleophilic aromatic substitution reaction involving a halobenzene electrophile, demonstrating that the solvent effects observed for ionic liquids are general for this type of reaction mechanism and opening the possibility for extending their use through rational selection for reaction control. 相似文献
113.
T. B. Pierce C. R. Boswell K. Haines 《Journal of Radioanalytical and Nuclear Chemistry》1972,10(1):83-88
Magnesium, almuinium and iron have been determined in sand at levels of >1% by inelastic neutron scattering. Neutrons were
obtained from a 1 Ci polonium-beryllium neutron source and analytical determination was based on measurement of the characteristic
γ-lines emitted during nuclear de-excitation. 相似文献
114.
alpha-quartz, which has been reported to undergo pressure-induced amorphization, was found to transform to a monoclinic, crystalline phase when compressed to 45 GPa at room temperature in a close to hydrostatic, helium pressure medium. The x-ray powder diffraction data obtained could be indexed based on a monoclinic cell, and the intensities are in agreement with a P2(1)/c model structure built up of 3x2 zigzag chains of SiO6 octahedra. This new polymorph of silica, which is metastable under ambient conditions, has been isolated for the first time and is one of several possible competing dense forms containing octahedrally coordinated silicon. 相似文献
115.
The development of the m = 0 instability in a Z pinch was followed and the measured growth rates compared with 2D MHD simulations. Where MHD is valid, the measured growth rates agree well with simulation. Where the ions are magnetized, i.e., where the ion-cyclotron frequency is smaller than the ion-collision frequency and the ratio of the ion Larmor radius to pinch radius is of the order of 0.1, the growth rate was smaller than expected by a factor of 2.5. This is as predicted by finite-Larmor-radius theory. The product of the wave number and the pinch radius was ka approximately 2pi and was the same for all conditions. Perturbations as large as 30% of the pinch radius were observed; no nonlinear saturation was evident. 相似文献
116.
Lebedev SV Beg FN Bland SN Chittenden JP Dangor AE Haines MG Pikuz SA Shelkovenko TA 《Physical review letters》2000,85(1):98-101
We present the first measurements by x-ray radiography of the development of instabilities during the implosion phase of wire array Z pinches. The seeding of perturbations on the dense core of each wire is provided by nonuniform sweeping of the low-density coronal plasma from the cores by the global JxB force. The spatial scale of these perturbations ( approximately 0.5 mm for Al and approximately 0.25 mm for W) is determined by the size of the wire cores ( approximately 0.25 mm for Al and approximately 0.1 mm for W). A qualitative change in implosion dynamics, with transition to 0D-like trajectory, was observed in Al arrays when the ratio of interwire gap to wire core size was decreased to approximately 3. 相似文献
117.
Lebedev SV Aliaga-Rossel R Bland SN Chittenden JP Dangor AE Haines MG Zakaullah M 《Physical review letters》2000,84(8):1708-1711
Two different modes of nested wire array implosion driven by a 1-MA, 240-ns current pulse were observed, determined by the fraction of total current induced in the inner array. Penetration by the outer array through the inner with switching of current occurred if current in the inner array was initially suppressed. Simultaneous implosion of arrays with apparent compression of magnetic flux between the arrays was observed if approximately 20% of the current was in the inner array. In both cases the x-ray pulse rise time of approximately 10 ns (for 260-ns implosion time) was considerably smaller than for a single array. 相似文献
118.
A High‐Temperature Molecular Ferroelectric Zn/Dy Complex Exhibiting Single‐Ion‐Magnet Behavior and Lanthanide Luminescence
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Dr. Jérôme Long Dr. Jérôme Rouquette Jean‐Marc Thibaud Dr. Rute A. S. Ferreira Prof. Dr. Luís D. Carlos Bruno Donnadieu Veaceslav Vieru Prof. Dr. Liviu F. Chibotaru Dr. Leszek Konczewicz Dr. Julien Haines Dr. Yannick Guari Prof. Dr. Joulia Larionova 《Angewandte Chemie (International ed. in English)》2015,54(7):2236-2240
Multifunctional molecular ferroelectrics are exciting materials synthesized using molecular chemistry concepts, which may combine a spontaneous electrical polarization, switched upon applying an electric field, with another physical property. A high‐temperature ferroelectric material is presented that is based on a chiral Zn2+/Dy3+ complex exhibiting Dy3+ luminescence, optical activity, and magnetism. We investigate the correlations between the electric polarization and the crystal structure as well as between the low‐temperature magnetic slow relaxation and the optical properties. 相似文献
119.
Thomas J. Haines 《manuscripta mathematica》2000,101(2):167-174
We consider the matrix for the Satake isomorphism with respect to natural bases. We give a simple proof in the case of Chevalley
groups that the matrix coefficients which are not obviously zero are in fact positive numbers. We also relate the matrix coefficients
to Kazhdan–Lusztig polynomials and to Bernstein functions.
Received: 29 June 1999 / Revised version: 7 September 1999 相似文献
120.