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121.
Dr. Subrata Saha Dr. Brice Kauffmann Dr. Yann Ferrand Dr. Ivan Huc 《Angewandte Chemie (International ed. in English)》2018,57(41):13542-13546
Xylobiose sequestration in a helical aromatic oligoamide capsule was evidenced by circular dichroism, NMR spectroscopy, and crystallography. The preparation of the 5 kDa oligoamide sequence was made possible by the transient use of acid‐labile dimethoxybenzyl tertiary amide substituents that disrupt helical folding and prevent double helix formation. Binding of other disaccharides was not detected. Crystallographic data revealed a complex composed of a d ‐xylobiose α anomer and two water molecules accommodated in the right‐handed helix. The disaccharide was found to adopt an unusual all‐axial compact conformation. A dense network of 18 hydrogen bonds forms between the guest, the cavity wall, and the two water molecules. 相似文献
122.
Yann Bugeaud 《Proceedings of the American Mathematical Society》1997,125(11):3203-3208
One of the purposes of this note is to correct the proof of a recent result of Y. Guo & M. Le on the equation . Moreover, we prove that the diophantine equation , , , , , gcd, , has only finitely many solutions, all of which satisfying .
123.
Favre F Villieras F Duval Y McRae E Rapin C 《Journal of colloid and interface science》2005,286(2):615-620
The influence of humidity on the electrical properties of alpha-Al2O3 powders has been investigated using adsorption isotherms, DC resistivity, and electrochemical impedance spectroscopy. Samples of two alpha-Al2O3 particle sizes were examined, both individually and mixed together. The results show that the grain-bed resistivity decreases with humidity, whereas the grain capacitance is almost constant. The resistivity difference between the two particle sizes is of several orders of magnitude, while the capacitance values are not very different. These results are interpreted in terms of the layer-by-layer growth of water adsorbed on the grain surfaces. The first, more tightly bound adsorbed layer does not provoke the same effects as those layers adsorbed at higher relative humidity. 相似文献
124.
The solid and solution structures of a new optically active aminopyridine compound, 2‐[(1S)‐(+)‐10‐camphorsulfonamino]‐6‐aminopyridine [(S)‐csaap], 1 , are reported. Crystal data: space group P21, a = 8.9729 (5), b = 10.9447 (6), c = 36.693 (2) Å, β = 96.435 (1)°, V = 3580.8 (3) Å3, Z = 8, R1 = 0.0673 and wR2 = 0.1600 with I > 2σ(I). This chiral compound shows an unprecedented cocrystallization of four stereoisomers, which are characterized by X‐ray crystallography and NMR spectroscopy. 相似文献
125.
Maw‐Cherng Suen Ymg‐Yann Wu Guo‐Chung Dong Jhy‐Der Chen Tai‐Chiun Keng Ju‐Chun Wang 《中国化学会会志》2002,49(3):331-334
The reaction of Zn(NO3)2·6H2O and bpp (bpp = 1,3‐Bis(4‐pyridyl)pronpane) in CH3OH afforded the complex [Zn(bpp)(NO3)2]n, 1 . The IR has been recorded and the structure has been determined. Crystal data for 1: Space group P2(1)/n, a = 11.749(1), b = 11.413(1), c = 11.942(1) Å, β = 96.06(6)°. V = 1592.5(3) Å3, Z = 4 with final residuals R1 = 0.0484 and wR2 = 0.0984. The complexes show supramolecular structure in the solid state by intermolecular hydrogen bonding interaction. 相似文献
126.
The binding of amyloid beta peptides (Abeta) to plasma membranes appears to be a promising point of intervention in the events leading to the development of Alzheimer's disease (AD). This binding has been studied as regards the direct toxicity of Abeta on neurons, and the activation of a local inflammation phase involving microglia. By virtue of its structure, Abeta is able to bind to a variety of biomolecules, including lipids, proteoglycans and proteins. This review focuses on the membrane proteins that can mediate the interaction between Abeta and the plasma membranes in AD. On neurons, these are APP (amyloid precursor protein), the NMDA-R (N-methyl-D-aspartate receptor), integrins, the alpha7nicotinic acetylcholine receptor (alpha7nAChR), the P75 neurotrophin receptor (P75NTR) and the CLAC-P/collagen type XXV (collagen-like Alzheimer amyloid plaque component precursor/collagen XXV). On glial cells, FPRL1 (formyl peptide receptor-like 1), the scavenger receptors A, BI (SR-A, SR-BI) and CD36, a complex involving CD36, alpha(6)beta(1)-integrin and CD47, and heparan sulfate proteoglycans have been reported to bind Abeta. It should be noted that integrins, RAGE (receptor for advanced glycosylation end-products), the Serpin-enzyme complex receptor (SEC-R) and the insulin receptor can bind Abeta and are present on neurons and on glial cells. After a presentation of the structure and the function of each of these proteins, the method used to prove their binding to Abeta is described, and the implication of this binding in AD is discussed. Finally, it is underlined that multireceptor complexes containing integrins may be involved in this interaction. 相似文献
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Rotating mechanical systems such as gearbox are known to generate vibrations at specific frequencies. The generation of asymmetric frequency sidebands around gear meshing frequencies is typical of rotating systems, and often results in amplitude-modulated disturbances. In addition, when the angular speed of such systems exhibits small time variations, a frequency-modulation of the disturbance tones is observed. Such conditions may result in difficulties for feedforward active control systems based on short, finite impulse response control filters, as was observed by previous researchers. This is mainly due to the fact that the reference signal may not provide all the gear meshing frequencies and sidebands found in the disturbance. This work investigates adaptive notch filters in the principal component space to cancel multi-harmonic gearbox vibrations. Experimental results obtained with these adaptive notch filters show good control attenuations at targeted gearbox tones, without amplification of other closely located, unreferenced tones. 相似文献