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91.
Peter Wick Anna E. Louw‐Gaume Melanie Kucki Harald F. Krug Kostas Kostarelos Bengt Fadeel Kenneth A. Dawson Anna Salvati Ester Vzquez Laura Ballerini Mauro Tretiach Fabio Benfenati Emmanuel Flahaut Laury Gauthier Maurizio Prato Alberto Bianco 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(30):7846-7850
92.
Potential energy calculations on the 2∶1 inclusion compound between deoxycholic acid and (+)-camphor
Sofia Candeloro De Sanctis Ester Chiessi Edoardo Giglio 《Journal of inclusion phenomena and macrocyclic chemistry》1985,3(1):55-64
The crystal structure of the 21 inclusion compound between deoxycholic acid and (+)-camphor has been solved by other authors. We have studied its crystal packing by potential energy calculations. Four arrangements of camphor, satisfactory from an energy point of view, were found and used to refine the crystal structure by a least-squares procedure. The results seem to indicate that more than one orientation is possible for the guest molecule and that the X-ray data do not allow us to establish which guest-molecule arrangements are actually present. 相似文献
93.
Tubaro M Marotta E Seraglia R Traldi P 《Rapid communications in mass spectrometry : RCM》2003,17(21):2423-2429
Benzene and toluene have been proposed previously as dopants in atmospheric pressure photoionization (APPI) experiments on compounds exhibiting ionization energies higher than the energy of photons used for irradiation. Their low ionization energies lead to their easy photoionization and the ions so formed lead to the ionization of analytes through charge exchange. However, some measurements have shown that some protonation reactions also take place, and a series of experiments was undertaken to investigate this unexpected behavior. It was shown that, when benzene is irradiated in the APPI source, the odd-electron molecular ions of phenol, diphenyl ether and phenoxyphenol are produced in high yield, together with protonated diphenyl ether and protonated phenoxyphenol. These results have been confirmed by deuterium labelling and MS(n) experiments. A possible mechanism is proposed, based on a radical attack by benzene molecular ions on oxygen molecules present inside the APPI source, analogous to that proposed in the literature for phenyl radicals. Similar results have been obtained with toluene, proving that APPI is able to activate a series of reactions leading to highly reactive species which are highly effective in promoting ionization of molecules with ionization energies higher than the photon energy. 相似文献
94.
Marotta E Scorrano G Paradisi C 《Rapid communications in mass spectrometry : RCM》2005,19(11):1447-1453
The positive ion chemistry occurring within an ion trap mass spectrometer upon electron ionization of 1-bromo-1-chloro-2,2,2-trifluoroethane, the important anaesthetic halothane, has been mapped by means of collision-induced decomposition and ion/molecule self-reaction experiments. Ionized halothane (M+*) reacts with neutral halothane to form the ionized olefin [ClBrC=CF2]+*. via HF elimination. Among the ionic fragments, [M-Br]+ and [M-F]+ react with halothane via chloride abstraction while [M-Cl]+ is unreactive under the same experimental conditions. Substituted methyl cations CHFX+ and CF2X+ (X = F, Cl, Br) undergo halide transfer processes, their reactivity being highest for X = F. Ionized carbenes CXY+ (X,Y = F,F; H,Br; H,Cl; H,F) react with halothane to form CClXY+ and CBrXY+, whereas CF+ inserts into the C-Cl bond to form CF3+ and CClF2+. Finally, Br+ and Cl+ react with halothane by charge transfer. Collision-induced dissociation experiments disclosed interesting rearrangements involved in the dissociations of +CHX-CF3 ions (X = Br, Cl), which undergo fluorine migration and elimination of CF2, as already observed for +CCl2-CF3 in a previous investigation. 相似文献
95.
Stable polymeric microballoons as multifunctional device for biomedical uses: synthesis and characterization 总被引:3,自引:0,他引:3
Cavalieri F El Hamassi A Chiessi E Paradossi G 《Langmuir : the ACS journal of surfaces and colloids》2005,21(19):8758-8764
Gas filled hollow microparticles, i.e., microbubbles and microballoons, are soft matter devices used in a number of diverse applications ranging from protein separation and purification in food science to drilling technology and ultrasound imaging. Aqueous dispersions of these mesoscopic systems are characterized by the stabilization of the air/water interface by a thin shell of phospholipid bilayer or multilayers or by a denatured and cross-linked proteic matrix. We present a study of a type of microballoons based on modified poly(vinyl alcohol), PVA, a synthetic biocompatible polymer, with new structural features. A cross-linking reaction carried out at the air/water interface provides polymeric air-filled microbubbles with average dimensions depending on the reaction temperature. Characterization of diameters and shell thicknesses for microbubbles obtained at different temperatures has been carried out. Conversion to solvent-filled hollow microcapsules is possible by soaking microbubbles in dimethyl sulfoxide. Microcapsules permeability to fluorescent labeled dextran molecular weight standards was correlated to the mesh size of the polymer network of the shell. Microbubbles were covalently grafted under very mild conditions with beta-cyclodextrin and poly-l-lysine with a view to assay the capability of the device for delivery of hydrophobic drugs or DNA. PVA based microballoons show a remarkable shelf life of several months, their external surface can be decorated with many biologically relevant molecules. These features, together with a tested biocompatibility, make them attractive candidates for use as multifunctional device for diagnosis and therapeutic purposes, i.e., as ultrasound reflectors in ecographic investigation and as drug platforms for in situ sonoporation. 相似文献
96.
Blanco M González JM Torras E Valverde I 《Analytical and bioanalytical chemistry》2003,375(1):157-163
A simple, fast capillary electrophoresis method for determining the total ketoprofen content in an oral pharmaceutical formulation is proposed. The addition of 75 mM of heptakis(tri- O-methyl)-beta-cyclodextrin to the background electrolyte allows the quantitation of the enantiomeric impurity of ( R)-(-)-ketoprofen contained in the formulation. A relative limit of detection is proposed as a measure of the lowest detectable enantiomeric impurity and the results show that the method can detect the minor enantiomer at levels as low as 0.04% in ( S)-(+)-ketoprofen. The chiral method was validated following ICH recommendations and the quality parameters obtained show the suitability of the proposed method. The analysis of samples examined during the course of a stability study under chiral and achiral conditions revealed that the total ketoprofen content did not change significantly with time and the enantiomeric impurity range was 0.1-0.4%. 相似文献
97.
Olaf D. Kinzel Edith Monteagudo Ester Muraglia Federica Orvieto Giovanna Pescatore Maria del Rosario Rico Ferreira Michael Rowley Vincenzo Summa 《Tetrahedron letters》2007,48(37):6552-6555
An efficient synthesis of methyl 9-amino-3-hydroxy-4-oxo-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidine-2-carboxylate as a late stage intermediate for a new class of HIV-1 integrase inhibitors is described. After construction of the bicyclic core scaffold, a stereoselective introduction of the chiral amino group in the 9-position is achieved. 相似文献
98.
Ester Giarrusso 《manuscripta mathematica》1986,54(4):381-390
We extend a method of K. Uhlenbeck for proving the partial regularity of solutions of nonlinear elliptic systems. We do not employ reverse Hölder type inequalities. 相似文献
99.
Otero L Folch C Barriga G Rigol C Opazo L Vieites M Gambino D Cerecetto H Norambuena E Olea-Azar C 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(3):519-523
Cyclic voltammetry (CV) and electron spin resonance (ESR) techniques were used in the investigation of novel palladium complexes with bioactive thiosemicarbazones derived from 5-nitrofurane or 5-nitrofurylacroleine. Sixteen palladium complexes grouped in two series of the formula [PdCl(2)HL] or [PdL(2)] were studied. ESR spectra of the free radicals obtained by electrolytic reduction were characterized and analyzed. The ESR spectra showed two different hyperfine patterns. The stoichiometry of the complexes does not seem to affect significantly the hyperfine constants however we observed great differences between 5-nitrofurane and 5-nitrofurylacroleine derivatives. The scavenger properties of this family of compounds were lower than Trolox. 相似文献
100.
Michela Di Giannantonio Dr. Mathieu A. Ayer Dr. Ester Verde‐Sesto Prof. Dr. Marco Lattuada Prof. Dr. Christoph Weder Prof. Dr. Katharina M. Fromm 《Angewandte Chemie (International ed. in English)》2018,57(35):11445-11450
The introduction of mechanophores into polymers makes it possible to transduce mechanical forces into chemical reactions that can be used to impart functions such as self‐healing, catalytic activity, and mechanochromic response. Here, an example of mechanically induced metal ion release from a polymer is reported. Ferrocene (Fc) was incorporated as an iron ion releasing mechanophore into poly(methyl acrylate)s (PMAs) and polyurethanes (PUs). Sonication triggered the preferential cleavage of the polymers at the Fc units over other bonds, as shown by a kinetic study of the molar mass distribution of the cleaved Fc‐containing and Fc‐free reference polymers. The released and oxidized iron ions can be detected with KSCN to generate the red‐colored [Fe(SCN)n(H2O)6?n)](3?n)+ complex or reacted with K4[Fe(CN)6] to afford Prussian blue. 相似文献