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131.
Francis M. Wampler Arthur T. Blades Paul Kebarle 《Journal of the American Society for Mass Spectrometry》1993,4(4):289-295
The total current and selected ion currents from the electrospray ionization (ES1) of 10?5 M solutions of cocaine hydrochloride and deoxycytidine monophosphate (dCMP) monosodium salt in methanol and water solvents were compared in positive and negative ion modes, respectively, without and with SF6, gas as a discharge suppressant. The ESI onset voltages (Von), were the same for the positive and negative ion modes. The Von, for methanol was much lower than that for water and in agreement with the equation of D. P. H. Smith, who attributes the difference to the higher surface tension of water. The onset of electric discharge (Vdis) without SF6, occurred at lower capillary voltages for the negative relative to the positive ion mode for methanol; but Vdis is much higher than Von for methanol, and discharges do not interfere with ESI operation. For water, Von ≈ Vdis in the absence of SF6, in the negative ion mode, and ESI operation is impossible without SF6, discharge suppression. The discharge problem in the positive ion mode is less severe, but SF6, is still very useful. A dynamic range of 10 ?7–10?5 M was obtained by selected ion monitoring of [dCMP - H]? at 4.5 and 20 μL/min. flows. Subpicomole detection limits for the nucleotide salt were obtained under these conditions. 相似文献
132.
Polyetheretherketone (PEEK) is a thermoplastic material with outstanding properties and high potential for biomedical applications, including hermetic encapsulation of active implantable devices. Different biomedical grade PEEK films with initial degree of crystallinity ranging from 8% to 32% (with or without mineral filling) were inspected. PEEK surfaces were treated with nitrogen RF plasma and the effects on materials crystallinity and self‐bonding were evaluated. In particular, the relationship between auto‐adhesive properties and crystalline content of PEEK before and after plasma treatment was examined. PEEK samples showed different bonding strength depending on their degree of crystallinity, with higher self‐bonding performance of mineral‐filled semi‐crystalline films. XRD did not show any modification of the PEEK microstructure as a result of plasma treatment, excluding a significant influence of crystallinity on the self‐bonding mechanisms. Nevertheless, plasma surface treatment successfully improved the self‐bonding strength of all the PEEK films tested, with larger increase in the case of semi‐crystalline unfilled materials. This could be interpreted to the increase in chain mobility that led to interfacial interpenetration of the amorphous phase. 相似文献
133.
Following the initial synthesis of the fuchsones1I, (α, η -diphenyl-1,4-benzoquinone methides), numerous substituted members of this series have been described by workers interested in triphenylmethane dyes. The fuchsones have been synthesized by the sulfuric acid condensation of benzilic acid and appropriate phenol1, by dehydration of 4-hydroxytriphenylcarbinol2, by oxidation 4-hydroxytri-phenylmethane and by photochemically induced reactions benzophenones with 2,6-dialkylphenols4. 相似文献
134.
Francis R. Costa Sudip Pradhan Udo Wagenknecht Anil K. Bhowmick Gert Heinrich 《Journal of Polymer Science.Polymer Physics》2010,48(22):2302-2311
In elastomer/organo clay nanocomposites, the morphological characteristics, and hence the mechanical properties, of the vulcanizates are strongly influenced by the organic modifier and the vulcanization process. When the elastomer itself undergoes strain‐induced crystallization, both the organic modifier and the dispersed filler particles could significantly influence the crystallization process. These phenomena are very common in case of natural rubber‐based vulcanizates. In this study, the similar effects have been demonstrated with carboxylated nitrile rubber (XNBR) and organically modified layered double hydroxide (O‐LDH)‐based nanocomposites. The effect of size of the organic modifier was obviously visible on the interlayer distance of O‐LDH and also on the morphological reorganization of the dispersed O‐LDH particles during vulcanization process. The strain‐induced crystallization of the XNBR was found to be strongly dependent on the morphological change that occurs during vulcanization process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010 相似文献
135.
Annabelle Ballesta Jean Clairambault Sandrine Dulong Francis Levi 《Applied Mathematics Letters》2011,24(7):1251-1256
The anticancer drug Irinotecan (CPT11) is known to trigger the induction of ATP-Binding Cassette (ABC) transporters, responsible for the efflux of the drug and its metabolites outside of the cells. The drug-modulated overexpression of those transporters prevents its accumulation in the intracellular medium, therefore decreasing its efficacy. A critical clinical concern lies in the design of CPT11-based therapeutic strategies which eradicate a maximum number of cancer cells despite their ability to become resistant. In order to address this issue, we supplemented an existing mathematical model of CPT11 molecular pharmacokinetics–pharmacodynamics (PK–PD) with a new model of CPT11-induced overexpression of ABC transporters. We then theoretically optimized exposure to CPT11 given as a single agent or combined either with ABC transporter inhibitors, or with inhibitors of nuclear factors whose activation is responsible for transporter overexpression. We firstly considered a cancer cell population endowed with the ability of inducing their transporters. For any drug combination, we concluded that the highest concentration of CPT11 should be administered in order to kill a maximum number of cancer cells, despite the triggering of resistance. We then considered a population of healthy cells which were assumed to be identical to cancer cells except that they were not able to become resistant. Optimal schemes were defined as the ones which maximized DNA damage in cancer cells under the constraint of DNA damage in healthy cells not exceeding a tolerability threshold. The optimal therapeutic strategy consisted in combining CPT11 with ABC transporter inhibitors as it achieved a complete reversal of resistance by means of the lowest concentrations of CPT11. 相似文献
136.
137.
Francis E. Burstall Udo Hertrich-Jeromin Wayne Rossman 《Comptes Rendus Mathematique》2010,348(11-12):661-664
We propose a Lie geometric point of view on flat fronts in hyperbolic space as special Ω-surfaces and discuss the Lie geometric deformation of flat fronts. 相似文献
138.
To establish the validity of the boundary-element method (BEM) for modeling scattering by swimbladder-bearing fish, the BEM is exercised in several ways. In a computation of backscattering by a 50-mm-diam spherical void in sea water at the four frequencies 38.1, 49.6, 68.4, and 120.4 kHz, agreement with the analytical solution is excellent. In computations of target strength as a function of tilt angle for each of 15 surface-adapted gadoids for which the swimbladders were earlier mapped, BEM results are in close agreement with Kirchhoff-approximation-model results at each of the same four frequencies. When averaged with respect to various tilt angle distributions and combined by regression analysis, the two models yield similar results. Comparisons with corresponding values derived from measured target strength functions of the same 15 gadoid specimens are fair, especially for the tilt angle distribution with the greatest standard deviation, namely 16 degrees. 相似文献
139.
Let ( G) be a flag-transitive c.c*-geometry whose point-stabilizer is not an affine group. We list all known examples and show that, if (, G) is a minimal unknown example, then G is an almost simple group and the commutator subgroup G is a simple group of Lie type. 相似文献
140.
M. De Micheli J. Botineau P. Sibillot D.B. Ostrowsky M. Papuchon 《Optics Communications》1982,42(2):101-103
We report the fabrication and characterization of optical waveguides realized in LiNbO3 by a combined titanium indiffusion proton exchange (TIPE) process. These guides provide several unique advantages which include permitting tailorong of guide birefringence, realizing proton exchanged Y-cut plates of good optical quality, and the realization of imbedded TM guides due to a lowering of no caused by proton exchange. 相似文献