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891.
892.
The paper reports the results of a study carried out to evaluate the use of three 1‐alkyl‐3‐methylimidazolium‐based ionic liquids as non‐covalent coating agents for bare fused‐silica capillaries and additives of the electrolyte solutions (BGE) for CE of basic proteins in the co‐EOF separation mode. The three ionic liquids are differentiated from each other by the length of the alkyl group on the imidazolium cation, consisting of either an ethyl, butyl or octyl substituent, whereas tetrafluoroborate is the common anionic component of the ionic liquids. Coating the capillary with the ionic liquid resulted in improved peak shape and protein separation, while the EOF was maintained cathodic. This indicates that each ionic liquid is effective at masking the protein interaction sites on the inner surface of the capillary, also when its adsorption onto the capillary wall has not completely neutralized all the negative charges arising from the ionization of the silanol groups and the ionic liquid is not incorporated into the BGE employed for separation. Using the coated capillaries with BGE containing the ionic liquid employed for the coating, at concentration low enough to maintaining the EOF cathodic, both peak shape and protein separation varied to different extents, based on the particular ionic liquid used and its concentration. Fast and efficient separation of the model basic protein mixture in co‐electroosmotic CE is obtained with the 1‐butyl‐3‐methylimidazolium tetrafluoroborate coated capillary and 100 mM acetate buffer (pH 4.0) containing 4.4 mM 1‐butyl‐3‐methylimidazolium tetrafluoroborate as the BGE. 相似文献
893.
Giuseppe Alì Vidar Furuholt Roberto Natalini Isabella Torcicollo 《Transport in Porous Media》2007,69(2):175-188
We present a numerical investigation of a degenerate nonlinear parabolic–elliptic system, which describes the chemical aggression
of limestones under the attack of SO2, in high permeability regime. This system has been introduced in the first part of this paper. We present a finite element
scheme for our model and its numerical stability is given under suitable CFL conditions. Numerical tests are discussed as
well as some examples of the numerical behavior of the solutions. 相似文献
894.
895.
896.
This paper is devoted to some selected topics relating Combinatorial Optimization and Hierarchical Classification. It is oriented
toward extensions of the standard classification schemes (the hierarchies): pyramids, quasi-hierarchies, circular clustering,
rigid clustering and others. Bijection theorems between these models and dissimilarity models allow to state some clustering
problems as optimization problems. Within the galaxy of optimization we have especially discussed the following: NP-completeness
results and search for polynomial instances; problems solved in a polynomial time (e.g. subdominant theory); design, analysis
and applications of algorithms. In contrast with the orientation to “new” clustering problems, the last part discusses some
standard algorithmic approaches.
This article appeared in 4OR 2, 179–219, 2004. 相似文献
897.
Isabella Nicotera Ameesh Khalfan Gabriel Goenaga Tao Zhang Andrew Bocarsly Steve Greenbaum 《Ionics》2008,14(3):243-253
Water and methanol transport behavior, morphology, and solvent adsorption of filler-free Nafion membrane, Nafion–SiO2, Nafion–TiO2, and two Nafion–Zr(HPO4)2 composites were investigated using nuclear magnetic resonance methods, including spin-lattice relaxation and pulsed-field-gradient
spin-echo diffusion conducted under both variable temperature and variable hydrostatic pressure conditions and scanning electron
microscopy analysis. A comparison between water and methanol self-diffusion coefficients reveals that the water mobility is
higher than the methanol mobility in all the membranes. Additionally, the inclusion of inorganic fillers improves both the
solvent uptakes and the transport properties of the composite membranes relative to filler-free Nafion, with the exception
of one of the Nafion–Zr(HPO4)2 composite. Nafion–Zr(HPO4)2 composites were prepared by two different procedures, in situ and ex situ. Although phosphorus-31 magic-angle spinning nuclear
magnetic resonance spectra show the same structures of the particles in both kinds of membranes, the morphology, solvent absorption
properties, and solvent mobilities are very different.
Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur Mer, Sept. 9–15, 2007. 相似文献
898.
H-start for exclusively heteronuclear NMR spectroscopy: The case of intrinsically disordered proteins 总被引:1,自引:1,他引:0
Wolfgang Bermel Ivano Bertini Veronika Csizmok Isabella C. Felli Roberta Pierattelli Peter Tompa 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2009,198(2):275-281
Here, we present a series of exclusively heteronuclear multidimensional NMR experiments, based on 13C direct detection, which exploit the 1H polarization as a starting source to increase the signal-to-noise ratio. This contributes to make this spectroscopy more useful and usable. Examples are reported for a suitable system such as securin, an intrinsically disordered protein of 22 kDa. 相似文献
899.
Julia Rousseau Jean‐Fran?ois Adam Pierre Deman Ting‐Di Wu Jean‐Luc Guerquin‐Kern Barbara Gouget Rolf F. Barth Fran?ois Estève Hélène Elleaume 《Journal of synchrotron radiation》2009,16(4):573-581
Iodine‐enhanced synchrotron stereotactic radiotherapy takes advantage of the radiation dose‐enhancement produced by high‐Z elements when irradiated with mono‐energetic beams of synchrotron X‐rays. In this study it has been investigated whether therapeutic efficacy could be improved using a thymidine analogue, 5‐iodo‐2′‐deoxyuridine (IUdR), as a radiosentizing agent. IUdR was administered intracerebrally over six days to F98 glioma‐bearing rats using Alzet osmotic pumps, beginning seven days after tumor implantation. On the 14th day, a single 15 Gy dose of 50 keV synchrotron X‐rays was delivered to the brain. Animals were followed until the time of death and the primary endpoints of this study were the mean and median survival times. The median survival times for irradiation alone, chemotherapy alone or their combination were 44, 32 and 46 days, respectively, compared with 24 days for untreated controls. Each treatment alone significantly increased the rats' survival in comparison with the untreated group. Their combination did not, however, significantly improve survival compared with that of X‐irradiation alone or chemotherapy alone. Further studies are required to understand why the combination of chemoradiotherapy was no more effective than X‐irradiation alone. 相似文献
900.
In the past seven years the size of the known protein sequence universe has been rapidly expanding. At present, more then five million entries are included in the UniProtKB/TrEMBL protein database. In this context, a retrospective evaluation of recent X‐ray absorption studies is undertaken to assess its potential role in metalloproteomics. Metalloproteomics is the structural and functional characterization of metal‐binding proteins. This is a new area of active research which has particular relevance to biology and for which X‐ray absorption spectroscopy is ideally suited. In the last three years, biological X‐ray absorption spectroscopy (BioXAS) has been included among the techniques used in post‐genomics initiatives for metalloprotein characterization. The emphasis of this review is on the progress in BioXAS that has emerged from recent meetings in 2007–2008. Developments required to enable BioXAS studies to better contribute to metalloproteomics throughput are also discussed. Overall, this paper suggests that X‐ray absorption spectroscopy could have a higher impact on metalloproteomics, contributing significantly to the understanding of metal site structures and of reaction mechanisms for metalloproteins. 相似文献