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21.
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《Physics letters. A》2014,378(5-6):480-483
We have shown in [1] that the invariant varieties of periodic points (IVPP) of all periods of some higher dimensional rational maps can be derived, iteratively, from the singularity confinement (SC). We generalize this algorithm, in this paper, to apply to any birational map, which has more invariants than the half of the dimension. 相似文献
23.
Anna Doppler Leo D.M. Nicholls Christopher Golz Manuel Alcarazo Michael John 《Magnetic resonance in chemistry : MRC》2019,57(11):961-967
Two functionalized [6]carbohelicenes, one of which was also available in its two enantiomeric pure forms, were oriented in stretched polystyrene in CDCl3, and in a recently introduced chiral thermoresponsive lyotropic polyaspartate (poly(benzyl)0.5(phenethyl)0.5-L-aspartate) in C2D2Cl4. From the resulting 1H,13C residual dipolar couplings, the helical pitch of a methylated [6]carbohelicene was determined and found to be in agreement with theoretical predictions and existing crystal structures (d(C2,C2′) ≈ 4.3 Å). For a second [6]carbohelicene with para-methoxyphenyl substituents, a clear conformational preference of the substituents was observed. The orientational properties of the two helicene enantiomers in the chiral polyaspartate are very similar, but both drastically change around 306 K. We suggest this behavior is due to an unusual phase transition in the liquid crystal. 相似文献
24.
Using fermionic basis we conjecture the exact formulae for the expectation values of local fields in sinh-Gordon model. The conjecture is checked against previously known results. 相似文献
25.
26.
Dionisia Sanz Rosa M. Claramunt François Mathey Ibon Alkorta Goar Sánchez-Sanz José Elguero 《Comptes Rendus Chimie》2013,16(10):937-944
This paper reports the study by NMR spectroscopy and ab initio methods of the structure of 3,4-dimethyl-1-cyanophosphole and its dimer. The dimer presents a P···P interaction of the pnictogen type due to the presence of σ-holes. NMR of the monomer was recorded in CDCl3 solution while NMR of the dimer corresponds to the solid state (CPMAS) experiments. The 2pJPP spin–spin coupling constant has not been measured, but calculated at the B3LYP level. AIM, NBO and ELF methodologies have been used to describe the electronic structure of the dimer. 相似文献
27.
J.R. Samaca Martinez J.-B. Le Cam X. Balandraud E. Toussaint J. Caillard 《Polymer Testing》2013,32(5):835-841
This paper deals with the calorimetric analysis of deformation processes in filled styrene-butadiene rubbers. More especially, the study focuses on the effects of the addition of carbon black fillers on the calorimetric response of “demullinized” SBR. Temperature variations are measured by infrared thermography during cyclic uniaxial tensile tests at ambient temperature. Heat sources1 produced or absorbed by the material due to deformation processes are deduced from temperature fields by using the heat diffusion equation. First, the results show that no mechanical (intrinsic) dissipation is detected for weakly filled SBR, meaning that the heat produced and absorbed over one mechanical cycle is the same whatever the stretch ratio reached. Second, the mechanical dissipation in highly filled SBR is significant. The quantitative analysis carried out highlights the fact that it increases quasi-linearly with the stretch ratio. Finally, a simplified framework is proposed to discuss the identification of the heat sources, in particular the mechanical dissipation. 相似文献
28.
Xiang Ying Shi Jue Lin Ziyang Li Tao Jin-Wang Huang Liang-Nian Ji 《Liquid crystals》2013,40(2):211-214
We observed that the planar aligned nematic liquid crystal (5CB) doped with a volume fraction of 1% of FeTPPCl [5,10,15,20-tetraphenylporphyriniron(III)chloride] or MnTPPCl [5,10,15,20-tetraphenylporphyrinmanganese(III)chloride] dramatically decreased the critical magnetic field for the magnetic field induced Freedericksz transition, while 5CB doped with ZnTPP [5,10,15,20-tetraphenylporphyrinzinc(II)] revealed no such effect, when compared with pure 5CB. In the guest-host (5CB) system, FeTPPCl and MnTPPCl as guests are both strong paramagnetic materials with an interaction through coordination of the -CN group in 5CB onto the metal ion of the porphyrin. As a result, the 5CB molecules are dragged to reorientate under a static magnetic field, while ZnTPP is a diamagnetic material without such a property. This phenomenon concerning magneto-optical components could be useful in liquid crystal displays. 相似文献
29.
Dr. Pablo Trigo‐Mouriño Dr. M. Carmen de la Fuente Dr. Roberto R. Gil Dr. Víctor M. Sánchez‐Pedregal Dr. Armando Navarro‐Vázquez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14989-14997
The conformational state of 8‐chloro‐1‐methyl‐2,3,4,5‐tetrahydro‐1H‐3‐benzazepine hydrochloride (lorcaserin) in water has been determined on the basis of one‐bond and long‐range C? H residual dipolar coupling (RDC) data along with DFT computations and 3JHH coupling‐constant analysis. According to this analysis, lorcaserin exists as a conformational equilibrium of two crown‐chair forms, of which the preferred conformation has the methyl group in an equatorial orientation. 相似文献
30.
Xanthine derivatives, caffeine (L1), theobromine (L2), theophylline (L3), 7-(β-hydroxyethyltheophylline) (L4), (7-(2,3-dihydroxypropyl)theophylline) (L5), and theophylline 7-acetic acid (L6) and the acetylated derivatives of the later three (L7–L9) were employed as ligands for the in situ palladium catalyzed Suzuki–Miyaura cross couplings of a series of halogenated pyridines. Optimized conditions were found where the diacetylated ligand (L8) was determined to be the best for this process, producing good to excellent yields in the couplings of halogenated anilines with phenylboronic acid under mild reaction conditions in water using microwave irradiation. 相似文献