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951.
A novel graphical presentation is proposed to convey information about relevant dynamic phenomena and behaviour of a rotor. The orbital tube is a three-dimensional plot in which the orbits are stacked in the third dimension at various rotating speeds. It may be conveniently used to represent and analyse data obtained from analytical, numerical and experimental means. Some illustrating examples are reported. 相似文献
952.
Ricci GB De Carli D Colonnese C Di Gennaro G Quarato PP Cantore G Esposito V Garreffa G Maraviglia B 《Magnetic resonance imaging》2004,22(10):1487-1492
We studied a new procedure of BOLD/fMRI acquisition in epilepsy. They use the benzodiazepine effect to achieve a more reliable baseline for statistical analysis. The method works only in the MR domain without EEG correlation. It compares the EPI images during interictal epileptic discharges and the images “inactivated” by benzodiazepine.
The results in five out of eight patients show that this procedure in comparison with the EEG/fMRI method gives a net improvement of spatial definition of BOLD areas. These preliminary results seem to confirm the hypothesis that the better BOLD/fMRI procedure in epilepsy is to make use of physical features of MR that, unlike EEG, is not influenced by the distance of intercerebral sources and consequently allows a more complete and undistorted display of BOLD areas. 相似文献
953.
Edward Clutton Valerie Rose Giancarlo Capaccio 《Journal of Macromolecular Science: Physics》2013,52(3-4):629-636
Recent advances in the analysis of the fracture behavior of polyethylene have been reviewed specifically to establish the nature and extent of morphological changes. It has been shown that in the case of linear low-density polyethylene (LLDPE), reorganization and orientation of lamellae occur in the shear lips region, the pattern being influenced by differences in molecular structure. Crazes, on the other hand, are characterized by the presence of voiding, with no significant effect on the original morphology. 相似文献
954.
Jean Colombani Guillaume Galliéro Bernard Duguay Jean-Paul Caltagirone François Montel Philippe A. Bopp 《哲学杂志》2013,93(17-18):2087-2095
We have used direct non-equilibrium molecular dynamics computer simulations to study the influence of an aluminosilicate slit pore on thermal diffusion in equimolar methane- n -decane. We have computed the Soret coefficient S T as a function of the pore width. The S T values deviate from those in a pore-free situation only for pores narrower than 35 Å. We have then investigated the possible causes for this deviation. We have noticed that the solid behaves as a thermal short circuit for the liquid but this has no consequence on the thermal and solutal profiles in the mixture. The main influence of the confinement of the liquid lies in the 'freezing' of the layer of molecules in contact with the pore walls. Outside this layer, the thermal diffusive behaviour of the mixture does not depart from that in the bulk fluid. This finding has enabled us to compute a 'corrected' Soret coefficient where the influence of the porous medium is eliminated. 相似文献
955.
Giancarlo Jug † 《哲学杂志》2013,93(33):3599-3615
An explanation is put forward for the early findings of Zeller and Pohl (, Phys. Rev. B, 4, 2029) and, in particular, Stephens (, Phys. Rev. B, 13, 852), and then for the more comprehensive recent findings of Meißner and Strehlow () for the anomalous magnetic-field-dependent behaviour of the heat capacity of some multicomponent glasses at low temperature (0.1?<?T?<?4?K) and in weak-to-moderate fields (0?<?B?<?8T). An essential new ingredient of this theory, together with the standard two-level system approach for cold glasses, is a multi-minima local potential for the quantum motion of metallic ions between near-degenerate wells, separated by relatively shallow barriers. Taking the tunneling entities as independent and assuming a novel probability distribution for the parameters of the multi-welled potential, an expression for the heat capacity C(T,B) is obtained with features that match rather well the reported unusual experimental data for the glasses. The indication coming from this theory for the data available is that the entities involved in tunnelling are nanoclusters of coherent ions. 相似文献
956.
Michele A. Forastiere Giancarlo C. Righini Massimo Brenci Stefano Pelli Monica Ferraris Daniel Milanese 《Optics and Lasers in Engineering》2003,39(3):333-344
The photorefractive properties of Ge-doped glasses are routinely exploited for the production of Bragg gratings in optical fibres. Today, the most common fabrication procedure relies on the phase-mask technique, which allows to produce (through UV irradiation) a periodical refractive index variation in Ge-doped fibre cores. The same methodology can be applied to integrated optical components in photorefractive glass planar substrates. If rare earth ions (such as erbium and ytterbium) are included in the glass matrix, both active and photorefractive properties can be combined in the same material. This fact allows for the possibility of realizing complex integrated optical components, such as Bragg-reflection lasers and amplifiers. In this work, a numerical analysis of a waveguide Bragg reflector is presented based on a homemade modelling technique. 相似文献
957.
Katalin Fodor-Csorba Antal Jákli Anikó Vajda S Krishna Prasad Doddamane S Shankar Rao Ronald Y Dong Jiadi Xu Giancarlo Galli 《Chemphyschem》2006,7(10):2184-2188
Novel, symmetrical, bent-core mesogens, namely substituted 1,3-phenylenebis{4'-[(ethoxycarbonyl)oxy]-1,1'-biphenyl}-4-carboxylates, are prepared with carbonate groups at both ends of the molecules. The mesophase properties are investigated for different electron-donating and -withdrawing substituents connected to the central ring at different positions. These compounds exhibit nematic and/or smectic A intercalated (SmA(int)) mesophases. Electro-optical studies show a very significant electric-field-induced biaxiality that is fast (<1 ms) and large (0.03) associated with a high birefringence (0.33 at 500 nm, 10 V mum(-1) field) for the unsubstituted analogue. For one substance this effect is observable from above 100 degrees C down to room temperature. Such electric-field-induced biaxiality may find practical applications in fast electro-optic modulation devices. 相似文献
958.
Maura Pellei Giancarlo Gioia Lobbia Riccardo Spagna 《Journal of organometallic chemistry》2006,691(8):1615-1621
New mono-, di- and tri-organotin(IV) derivatives containing the neutral bis(2-pyridylthio)methane ligand, [(pyS)2CH2] and tris(2-pyridylthio)methane ligand, [(pyS)3CH] have been synthesized from reaction with SnRnCl4−n (R = Me, nBu, Ph and Cy, n = 1-3) acceptors. Mono-nuclear adducts of the type {[(pyS)2CH2]RnSnCl4−n} and {[(pyS)3CH]RnSnCl4−n} have been obtained and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear (1H and 119Sn) NMR spectral data. The 1H and 119Sn NMR and ESI-MS data suggest for the triorganotin(IV) derivatives a complete dissociation of the compounds in solution. The mono- and di-organotin(IV) derivatives show a greater stability in solution, and their spectroscopic data are in accordance with the existence of six-coordinated RSnCl3N2 or R2SnCl2N2 species. 相似文献
959.
Gelson Perin Raquel G. Jacob Giancarlo V. Botteselle Rogério A. Freitag 《Tetrahedron letters》2005,46(10):1679-1682
A simple, clean, and efficient solvent-free protocol was developed for hydrochalcogenation of methyl propiolate derivatives with phenylchalcogenolate anion generated in situ from the respective diphenyl dichalcogenide (S, Se, Te) using alumina supported sodium borohydride. This efficient and improved method is general and furnishes the (Z)-β-phenylchalcogeno-α,β-unsaturated esters in yields and with selectivity comparable to those using organic solvent and inert atmosphere. The use of MW irradiation facilitates the procedure and accelerates the reaction. 相似文献
960.
Giuseppe Carlucci Paola Palumbo Piera Iuliani Giancarlo Palumbo 《Biomedical chromatography : BMC》2009,23(7):759-763
A simple high‐performance liquid chromatographic (HPLC) method with photometric detection is described for the determination of vardenafil hydrochloride, a phosphodiesterase V inhibitor, in human plasma. Chromatographic separation of the analyte and internal standard was achieved on an analytical 250 × 4.6 mm i.d. reversed‐phase Kromasil KR 100 C18 (5 µm particle size) column using a mobile phase of acetonitrile–potassium dihydrogen phosphate (30:70 v/v). The run time was less than 15 min. Column eluate was monitored at 230 nm. The linearity over the concentration range of 10–1500 ng/mL for vardenafil was obtained and the limit of quantification (LOQ) was 10 ng/mL. The method has been applied to analysis of the vardenafil concentrations for application in pharmacokinetic studies. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献