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681.
Emma Dichi Mehrez Sghaier Nicolas Guiblin 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2141-2155
Many drug candidates are poorly soluble. The formation of solid dispersion can improve their solubility, consequently their bioavailability. For this purpose, the use of eutectic mixtures is well known in the pharmaceutical field. At the eutectic composition, both components are in reduced particle size and well dispersed. In this work, we focus on the combination of paracetamol, aspirin, and caffeine, which is highly effective for the treatment of migraine headache pain. We have reinvestigated the paracetamol–caffeine, aspirin–caffeine, and paracetamol–aspirin phase equilibria diagrams taking into account the polymorphism of caffeine, paracetamol, and aspirin. The three phase diagrams are determined using X-ray diffraction and the differential scanning calorimetry from the binary mixtures. It is concluded that the paracetamol–caffeine and aspirin–caffeine systems are similar and exhibit two invariants, one eutectic and one metatectic. The paracetamol–aspirin phase diagram reveals the formation of one eutectic. The composition of the three eutectics formed is confirmed by the related Tamman’s triangles. No compound formation is found in the three systems. 相似文献
682.
683.
Preparing to read the ubiquitin code: characterization of ubiquitin trimers by top‐down mass spectrometry
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Amanda E. Lee Lucia Geis‐Asteggiante Emma K. Dixon Yeji Kim Tanuja R. Kashyap Yan Wang David Fushman Catherine Fenselau 《Journal of mass spectrometry : JMS》2016,51(4):315-321
The profound effects of ubiquitination on the movement and processing of cellular proteins depend exquisitely on the structures of monoubiquitin and polyubiquitin modifications. Unconjugated polyubiquitins also have a variety of intracellular functions. Structures and functions are not well correlated yet, because the structures of polyubiquitins and polyubiquitin modifications of proteins are difficult to decipher. We are moving towards a robust strategy to provide that structural information. In this report electron transfer dissociation mass spectra of six synthetic ubiquitin trimers (multiply branched proteins with molecular masses exceeding 25 600 Da) are examined using an Orbitrap Fusion Lumos instrument to determine how top‐down mass spectrometry can characterize the chain topology and linkage sites in a single, facile workflow. The efficacy of this method relies on the formation, detection, and interpretation of extensive fragmentation. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
684.
Leong TG Lester PA Koh TL Call EK Gracias DH 《Langmuir : the ACS journal of surfaces and colloids》2007,23(17):8747-8751
We discuss finite element simulations and experiments involving the surface tension-driven self-folding of patterned polyhedra. Two-dimensional (2D) photolithographically patterned templates folded spontaneously when solder hinges between adjacent faces were liquefied. Minimization of interfacial free energy of the molten solder with the surrounding fluidic medium caused the solder to ball up, resulting in a torque that rotated adjacent faces and drove folding. The simulations indicate that the folding process can be precisely controlled, has fault tolerance, and can be used to fold polyhedra composed of a variety of materials, ranging in size from the millimeter scale down to the nanometer scale. Experimentally, we have folded metallic, arbitrarily patterned polyhedra ranging in size from 2 mm to 15 microm. 相似文献
685.
Griffiths-Jones CM Hopkin MD Jönsson D Ley SV Tapolczay DJ Vickerstaffe E Ladlow M 《Journal of combinatorial chemistry》2007,9(3):422-430
A fully automated flow-through process for the production of secondary sulfonamides is presented. Primary sulfonamides were monoalkylated using a two-step "catch and release" protocol to generate library products of high purity. The automated flow synthesis platform incorporates four independent reactor columns and is able to perform automated column regeneration. A 48-member sulfonamide library was prepared as two 24-member sublibraries, affording library compounds in good yields and high purities without the need for further column chromatographic purification. 相似文献
686.
Walter Navarrini Francesco Venturini Maurizio Ursini Giuseppe Resnati Emma Barchiesi 《Journal of fluorine chemistry》2008,129(8):680-685
In the reaction between perfluoroolefins and perfluoroalkylhypofluorites the existence of two different free radical reaction mechanisms is demonstrated by the presence of characteristic byproducts. These kinetic schemes can be experimentally controlled by tuning the hypofluorite concentration in the reaction media.In particular, in the reactions between trifluoromethyl hypofluorite and highly reactive perfluoroolefins like CF2CFOCF3 and CF2CF2, the free radical oligomerization and dimerization products can be suppressed by utilizing the opportune experimental conditions.The pure perfluorinated ethers obtained, having low Ostwald coefficient, can be utilized as contrast agents for diagnostic ultrasound imaging injectable microbubbles composition. 相似文献
687.
Emma H. Chukhajian Martiros K. Nalbandyan Hasmik R. Gevorkyan Eliza H. Chukhajian Henrik A. Panosyan Armen G. Ayvazyan Rafael A. Tamazyan 《Journal of heterocyclic chemistry》2008,45(3):687-692
688.
The synthesis and photophysical evaluations of two new fluorescent photoinduced electron-transfer (PET) anion sensors, 1 and 2, is described. These are based on 4-amino-1,8-naphthalimide fluorophores and diarylthiourea anion receptors, connected via a methylene spacer to the imide. The sensing of acetate, phosphate, and fluoride, on all occasions, gave rise to quenching in the fluorescence of 1 and 2, similar to that seen for the structural isomer 3. These results demonstrate that bidirectional PET sensing occurs in such naphthalimide-based anion sensors. 相似文献
689.
Atomistic modelling studies of the apatite-type oxide ion conductor La9.33(GeO4)6O2 show that a key role of the O4 channel oxygen atoms appears to be as a reservoir for the creation of interstitial oxide ion defects, while the migration of these defects proceeds via the GeO4 tetrahedra. 相似文献
690.