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Estelle Mossou Susana C. M. Teixeira Edward P. Mitchell Sax A. Mason Lihi Adler‐Abramovich Ehud Gazit V. Trevor Forsyth 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(3):326-331
The title zwitterion (2S)‐2‐azaniumyl‐1‐hydroxy‐3‐phenylpropan‐1‐olate, C9H11NO2, also known as L‐phenylalanine, was characterized using synchrotron X‐rays. It crystallized in the monoclinic space group P21 with four molecules in the asymmetric unit. The 0.62 Å resolution structure is assumed to be closely related to the fibrillar form of phenylalanine, as observed by electron microscopy and electron diffraction. The structure exists in a zwitterionic form in which π–π stacking and hydrogen‐bonding interactions are believed to form the basis of the self‐assembling properties. 相似文献
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Julien Ramier Meyssoun Ben Boubaker Mohamed Guerrouache Valérie Langlois Daniel Grande Estelle Renard 《Journal of polymer science. Part A, Polymer chemistry》2014,52(6):816-824
Straightforward and versatile routes to functionalize the surface of poly(3‐hydroxyalkanoate) (PHA) electrospun fibers for improving cell compatibility are reported under relatively mild conditions. The modification of nanofibrous PHAs is implemented through two different methodologies to introduce epoxy groups on the fiber surface: (1) preliminary chemical conversion of double bonds of unsaturated PHAs into epoxy groups, followed by electrospinning of epoxy‐functionalized PHAs blended with nonfunctionalized PHAs, (2) electrospinning of nonfunctionalized PHAs, followed by glycidyl methacrylate grafting polymerization under UV irradiation. The latter approach offers the advantage to generate a higher density of epoxy groups on the fiber surface. The successful modification is confirmed by ATR‐FTIR, Raman spectroscopy, and TGA measurements. Further, epoxy groups are chemically modified via the attachment of a peptide sequence such as Arg‐Gly‐Asp (RGD), to obtain biomimetic scaffolds. Human mesenchymal stromal cells exhibit a better adhesion on the latter scaffolds than that on nonfunctionalized PHA mats. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 816–824 相似文献
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Richard Li Erica F. Antunes Estelle Kalfon‐Cohen Akira Kudo Luiz Acauan Wei‐Chang D. Yang Canhui Wang Kehang Cui Andrew H. Liotta Ananth Govind Rajan Jules Gardener David C. Bell Michael S. Strano J. Alexander Liddle Renu Sharma Brian L. Wardle 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(27):9302-9307
Synthesis of low‐dimensional carbon nanomaterials such as carbon nanotubes (CNTs) is a key driver for achieving advances in energy storage, computing, and multifunctional composites, among other applications. Here, we report high‐yield thermal chemical vapor deposition (CVD) synthesis of CNTs catalyzed by reagent‐grade common sodium‐containing compounds, including NaCl, NaHCO3, Na2CO3, and NaOH, found in table salt, baking soda, and detergents, respectively. Coupled with an oxidative dehydrogenation reaction to crack acetylene at reduced temperatures, Na‐based nanoparticles have been observed to catalyze CNT growth at temperatures below 400 °C. Ex situ and in situ transmission electron microscopy (TEM) reveal unique CNT morphologies and growth characteristics, including a vaporizing Na catalyst phenomenon that we leverage to create CNTs without residual catalyst particles for applications that require metal‐free CNTs. Na is shown to synthesize CNTs on numerous substrates, and as the first alkali group metal catalyst demonstrated for CNT growth, holds great promise for expanding the understanding of nanocarbon synthesis. 相似文献
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Cornelia Weber Estelle Gauda Boris Mizaikoff Christine Kranz 《Analytical and bioanalytical chemistry》2009,395(6):1729-1735
A novel concept for a dual-enzyme-based microbiosensor for the detection of adenosine-5′-triphosphate (ATP) was developed. The employed enzymes pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) and hexokinase were entrapped, using pH-shift-induced precipitation of electrodeposition paint (EDP) at platinum microelectrodes (diameter of 25 µm). PQQ-GDH is known showing a superior activity for glucose conversion at the relevant conditions (low oxygen concentration) for ATP detection in targeted biomedical studies. For immobilizing the two enzymes PQQ-GDH and hexokinase, the deposition conditions of EDP Resydrol AY498w/35WA were adapted to ensure high immobilization rates. Prior to ATP sensing, the conversion of glucose, which is the co-substrate for both enzymatic reactions, was optimized. Optimization was targeted towards ATP measurements in biomedical environments by optimizing the PQQ-GDH sensor for glucose. Therefore, different mediators were tested regarding their electron transfer rate and their compatibility with the enzyme: free-diffusing N-methylphenazonium methyl sulfate (PMS) and ferrocenemethanol, and an immobilized chromium hexacyanoferrate layer at platinum electrode. Free-diffusing ferrocenemethanol reveals high sensitivity towards glucose of 1.5?±?0.4 nA/mM. In a next step, hexokinase was co-entrapped in the polymer film resulting in a sensitivity of up to 290 pA/µM. 相似文献
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A spectral collocation method is used to solve the linearized Euler equations in a duct with shear flow and lined walls in order to identify a possible hydrodynamic instability observed in published experiments. This method is first checked against a reference test case in a cylindrical duct. Then a theoretical test case in a plane bi-dimensional duct with no-slip flow is considered: the Briggs-Bers stability criterion is proved to be valid and it shows that the hydrodynamic instability does correspond to a right-running amplified wave. Eigenmode analyses are then performed on the experimental configuration. An unstable hydrodynamic surface mode is found, with an axial wavenumber and velocity eigenfunctions which are in good agreement with the experimental ones. Acoustic energy calculations show that the hydrodynamic instability paradoxically carries noticeable levels of acoustic energy in the upstream direction. Finally, the influence of Mach number and frequency is investigated. 相似文献
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Enzymatic desulfation of stable glucoraphenin affords desulfoglucoraphenin, which unexpectedly undergoes further transformations into cyclic nitrone-type derivatives. 相似文献
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We report a new method for preparation of hydroxyacids as precursors of benzolactones using a simple and an efficient electrochemical step. This gives in only four steps six- to eleven-membered lactones with high isolated yields from conveniently substituted aryl bromides. The lactonisation was performed according to the Yamamoto's process. 相似文献