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561.
Rauwald U del Barrio J Loh XJ Scherman OA 《Chemical communications (Cambridge, England)》2011,47(21):6000-6002
The chain end complexation of a functional PNIPAM by a cucurbit[8]uril-viologen complex causes a shift in its lower critical solution temperature (LCST) by over 5 °C. An instantaneous phase change of the thermally responsive polymer beyond its LCST can be induced by addition of the aqueous cucurbituril host-guest complex. Subsequent decomplexation upon addition of a competitive guest releases the PNIPAM terminus and triggers complete reversibility. 相似文献
562.
563.
Florian Fusseis Holger Steeb Xianghui Xiao Wen‐lu Zhu Ian B. Butler Stephen Elphick Urs Mäder 《Journal of synchrotron radiation》2014,21(1):251-253
A new modular X‐ray‐transparent experimental cell enables tomographic investigations of fluid rock interaction under natural reservoir conditions (confining pressure up to 20 MPa, pore fluid pressure up to 15 MPa, temperature ranging from 296 to 473 K). The portable cell can be used at synchrotron radiation sources that deliver a minimum X‐ray flux density of 109 photons mm?2 s?1 in the energy range 30–100 keV to acquire tomographic datasets in less than 60 s. It has been successfully used in three experiments at the bending‐magnet beamline 2BM at the Advanced Photon Source. The cell can be easily machined and assembled from off‐the‐shelf components at relatively low costs, and its modular design allows it to be adapted to a wide range of experiments and lower‐energy X‐ray sources. 相似文献
564.
Electron deficient purines can be reduced to 7,8-dihydropurines when treated with cheap and easy-to-handle sodium borohydride in methanol. The dihydropurine formed by reduction of tris-Boc-protected adenine is a useful intermediate in efficient syntheses of 7-alkyladenines and tetrahydro[1,4]diazepino[1,2,3-gh]purines. 相似文献
565.
566.
This Letter reports on the fabrication and characterization of silicon heterojunction solar cells with silicon oxide based buffer (intrinsic amorphous silicon oxide) and contact layers (doped microcrystalline silicon oxide) on flat p‐type wafers. The critical dependency of the cell performance on the front and rear buffer layer thickness reveals a trade‐off between the open circuit voltage Voc and the fill factor FF. At the optimum, the highest efficiency of 18.5% (active area = 0.67 cm2) was achieved with Voc = 664 mV, short circuit current Jsc = 35.7 mA/cm2 and FF = 78.0%. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
567.
Graham Smith Urs D. Wermuth 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(9):o327-o331
The structures of the open‐chain amide carboxylic acid rac‐cis‐2‐[(2‐methoxyphenyl)carbamoyl]cyclohexane‐1‐carboxylic acid, C15H19NO4, (I), and the cyclic imides rac‐cis‐2‐(4‐methoxyphenyl)‐3a,4,5,6,7,7a‐hexahydroisoindole‐1,3‐dione, C15H17NO3, (II), chiral cis‐3‐(1,3‐dioxo‐3a,4,5,6,7,7a‐hexahydroisoindol‐2‐yl)benzoic acid, C15H15NO4, (III), and rac‐cis‐4‐(1,3‐dioxo‐3a,4,5,6,7,7a‐hexahydroisoindol‐2‐yl)benzoic acid monohydrate, C15H15NO4·H2O, (IV), are reported. In the amide acid (I), the phenylcarbamoyl group is essentially planar [maximum deviation from the least‐squares plane = 0.060 (1) Å for the amide O atom] and the molecules form discrete centrosymmetric dimers through intermolecular cyclic carboxy–carboxy O—H...O hydrogen‐bonding interactions [graph‐set notation R22(8)]. The cyclic imides (II)–(IV) are conformationally similar, with comparable benzene ring rotations about the imide N—Car bond [dihedral angles between the benzene and isoindole rings = 51.55 (7)° in (II), 59.22 (12)° in (III) and 51.99 (14)° in (IV)]. Unlike (II), in which only weak intermolecular C—H...Oimide hydrogen bonding is present, the crystal packing of imides (III) and (IV) shows strong intermolecular carboxylic acid O—H...O hydrogen‐bonding associations. With (III), these involve imide O‐atom acceptors, giving one‐dimensional zigzag chains [graph‐set C(9)], while with the monohydrate (IV), the hydrogen bond involves the partially disordered water molecule which also bridges molecules through both imide and carboxy O‐atom acceptors in a cyclic R44(12) association, giving a two‐dimensional sheet structure. The structures reported here expand the structural database for compounds of this series formed from the facile reaction of cis‐cyclohexane‐1,2‐dicarboxylic anhydride with substituted anilines, in which there is a much larger incidence of cyclic imides compared to amide carboxylic acids. 相似文献
568.
In this note we prove that the space of linear anti-symplectic involutions is the homogenous space ${{{\rm Gl}(n, \mathbb{R})\backslash{\rm Sp}(n)}}$ . This result is motivated by the study of symmetric periodic orbits in the restricted 3-body problem. 相似文献
569.
In [EH89, Theorem 1] Ekeland-Hofer prove that for a centrally symmetric, restricted contact type hypersurface in ℝ2n
and for any global, centrally symmetric Hamiltonian perturbation there exists a leaf-wise intersection point. In this note
we show that if we replace restricted contact type by star-shaped, there exist infinitely many leaf-wise intersection points
or a leaf-wise intersection point on a closed characteristic. 相似文献
570.
If the homology of the free loop space of a closed manifold B is infinite dimensional then generically there exist infinitely many leaf-wise intersection points for fiberwise star-shaped hypersurfaces in T∗B. We illustrate this in the case of the restricted three body problem. 相似文献