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41.
Guy Koeckelberghs Leen De Groof Isabel Picard Thierry Verbiest Andr Persoons Celest Samyn 《Macromolecular rapid communications》2005,26(11):905-910
Summary: In this paper two new donor‐embedded polybinaphthalenes prepared by the Heck reaction are presented. By introducing a double bond in the polymer backbone, the supramolecular structure was altered in comparison with polymers without the double bond. Comparison between the CD/UV‐Vis spectra of polymers, with and without the double bond (previously synthesized in our laboratory) proved this change in a supramolecular structure. The double bonds also allow crosslinking upon heat treatment. NLO experiments demonstrated a more stable nonlinearity over time depending on the degree of crosslinking.
42.
Phase field modelling has proven to be a versatile tool for simulating microstructural evolution phenomena, such as grain growth in polycrystalline materials. However, the computational requirements of a phase field model impose strong limitations on the number of phase field variables employed in a practical implementation. In this paper, a bounding box algorithm is proposed allowing the use of a large number of phase field variables without excessive computational requirements. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
43.
Nele De Schepper Dixan Peña Peña Frank Sommen 《Mathematical Methods in the Applied Sciences》2014,37(17):2704-2715
In this paper, we investigate a Cauchy–Kowalevski (CK) extension problem that arises naturally within the framework of Hermitian Clifford analysis, which concerns the study of Dirac‐like operators in several complex variables. The work presented here includes CK extensions of higher codimension and in particular the CK extension of the Gauss distribution in several complex variables. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
44.
A.D. Naik G. Fontaine F. Samyn X. Delva Y. Bourgeois S. Bourbigot 《Polymer Degradation and Stability》2013
An integrated multicomponent molecule, Melamine-poly(aluminium phosphate) (Safire®200), its zinc and magnesium analogues namely Safire®400 and Safire®600 respectively were used as flame retardants for glass fiber reinforced polyamide 66 in combination with aluminium phosphinate. Characterisation, thermal stability, combustion properties, glow-wire flammability index and glow-wire ignition temperature and cone calorimetry results are reported. Lower threshold of loading of flame retardants that pass V0 rating in UL-94 vertical burning test have been determined. Effect of Zinc borate (Firebrake®500 grade) in these formulations was investigated. Influence of additives on endothermic and exothermic transitions of polyamide 66 in these formulations were studied by differential scanning calorimetry. The formulations were evaluated against the properties and fire performances of classical commercial combination of aluminium phosphinate and melamine polyphosphate. All the new formulations down to 15% of additives loading achieve V0 rating according to UL-94 protocol. This synergistic combination of additives significantly reduces the peak of heat release rate (pHRR) and total heat release (THR) in formulations exhibiting various degrees of intumescence. 相似文献
45.
Hendrik De Bie Nele De Schepper Frank Sommen 《Journal of Fourier Analysis and Applications》2011,17(6):1198-1231
Recently, there has been an increasing interest in the study of hypercomplex signals and their Fourier transforms. This paper
aims to study such integral transforms from general principles, using 4 different yet equivalent definitions of the classical
Fourier transform. This is applied to the so-called Clifford-Fourier transform (see Brackx et al., J. Fourier Anal. Appl.
11:669–681, 2005). The integral kernel of this transform is a particular solution of a system of PDEs in a Clifford algebra, but is, contrary
to the classical Fourier transform, not the unique solution. Here we determine an entire class of solutions of this system
of PDEs, under certain constraints. For each solution, series expressions in terms of Gegenbauer polynomials and Bessel functions
are obtained. This allows to compute explicitly the eigenvalues of the associated integral transforms. In the even-dimensional
case, this also yields the inverse transform for each of the solutions. Finally, several properties of the entire class of
solutions are proven. 相似文献
46.
Braunschweig H Buggisch N Englert U Homberger M Kupfer T Leusser D Lutz M Radacki K 《Journal of the American Chemical Society》2007,129(15):4840-4846
The homoleptic sandwich complex bis(benzene)molybdenum, [Mo(eta6-C6H6)2], was successfully dilithiated by employing an excess of BuLi in the presence of N,N,N',N'-tetramethylethylenediamine (up to 6 equiv each) at slightly elevated temperatures furnishing the highly reactive, ring metalated species [Mo(eta6-C6H5Li)2].tmeda in high yields. Alternatively, this compound was synthesized upon prolonged sonication with 5 equiv of tBuLi/tmeda without heating. An X-ray crystal structure determination revealed a symmetrical, dimeric composition in the solid state, i.e., a formula of [Mo(eta6-C6H5Li)2]2.(thf)6, where the six-membered rings are connected by two pairs of bridging lithium atoms. The synthesis of an elusive ansa-bridged complex failed in the case of a [1]bora and a [1]sila bridge due to the thermal lability of the resulting compounds. Instead, reverse addition of the dilithio precursor to an excess of the appropriate element dihalide facilitated the isolation of several unstrained, 1,1'-disubstituted derivatives, namely, [Mo{eta6-C6H5(BN(SiMe3)2X)}2] (X = Cl, Br) and [Mo{eta6-C6H5(SiiPr2Cl)}2], respectively. However, the incorporation of a less congesting [2]sila bridge was accomplished. In addition to the formation of [Mo{(eta6-C6H5)2Si2Me4}], a molybdenum-containing paracylophane complex was isolated and characterized by means of crystal structure analysis. The ancillary formation of 1 equiv of bis(benzene)molybdenum strongly suggests that this species is generated by deprotonation of the ansa-bridged complex by the dilithiated precursor and subsequent reaction with a second equivalent of the disilane. 相似文献
47.
In this work, we explain our astrophysical motivations for deriving a mass formula based on HFB calculations with a Skyrme
interaction. We give an overview of existing mass formulae and present briefly the last HF+BCS mass formula [1]. The Skyrme
force MSk7 [1] is considered in the study of shell effects at N=82, in the neutron-rich region far from stability, within the HFB and HF+BCS theories, and compared with results obtained
using the forces SkPδ and SkPδρ [2].
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
48.
49.
50.
The thermal behaviour of a mixture containing an ammonium polyphosphate based compound (AP760) and zinc borate (ZB) is investigated. After an investigation of the degradation of the pure components, the interactions between them are examined by thermogravimetry. Then, X-ray diffraction (XRD) and 11B and 31P solid-state nuclear magnetic resonance (NMR) measurements have been carried out on residues of mixtures of AP760 and FBZB heat treated at different characteristic temperatures. It reveals the nature of the interactions taking place between the two components. It is demonstrated that reactions lead to the formation of zinc phosphate and of borophosphates. Mechanisms of thermal degradation are proposed. 相似文献