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251.
252.
Mario Luzón Teresa Corrales Fernando Catalina Verónica San Miguel Carmen Ballesteros Carmen Peinado 《Journal of polymer science. Part A, Polymer chemistry》2010,48(22):4909-4921
A series of amphiphilic triblock copolymers, poly[oligo(ethylene glycol) methacrylate]x‐block‐poly(ε‐caprolactone)‐block‐poly[oligo(ethylene glycol) methacrylate]x, POEGMACo(x), were synthesized. Formation of hydrophobic domains as cores of the micelles was studied by fluorescence spectroscopy. The critical micelle concentrations in aqueous solution were found to be in the range of circa 10?6 M. A novel methodology by modulated temperature differential scanning calorimetry was developed to determine critical micelle temperature. A significant concentration dependence of cmt was found. Dynamic light scattering measurements showed a bidispersed size distribution. The micelles showed reversible dispersion/aggregation in response to temperature cycles with lower critical solution temperature between 75 and 85 °C. The interplay of the two hydrophobic and one thermoresponsive macromolecular chains offers the chance to more complex morphologies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
253.
Julieta I. Paez Pablo Froimowicz Katharina Landfester Verónica Brunetti Miriam Strumia 《Journal of polymer science. Part A, Polymer chemistry》2014,52(22):3185-3197
The synthesis of nanoparticle‐cored dendrimers (NCDs) through surface functionalization of iron oxide nanoparticles (γ‐Fe2O3) by combining the conventional silane coupling agent 3‐(aminopropyl) triethoxysilane (APS) with dendritic moieties is studied and presented. Much emphasis has been put on the role played by each modifier and how they interact not only between themselves, but also with the dispersing media wherein the resulting NCDs are. As a part of the functionalization, redox‐active nitro groups were introduced onto the surface of each synthesized NCD thus making them electrochemically active. Then, the obtained NCDs were immobilized onto glassy carbon electrodes. Both the NCDs and modified electrodes are expected to be eventually exploited in analytical and sensing applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3185–3197 相似文献
254.
255.
Verónica Salazar-Pereda Francisco Javier Martínez-Martínez Rosalinda Contreras Angelina Flores-Parra 《Journal of carbohydrate chemistry》2013,32(9):1479-1507
Abstract We have determined the preferred conformers in solution by a detailed NMR analysis using COSY and HETCOR experiments of three inositol isomers: myo (1), scyllo (2) and epi (3) plus sixteen derivatives of myo-inositol: 1,2,3,4,5,6-hexa-O-acetyl-myo-inositol (4), 1,2,-O-isopropylidene-myo-inositol (5), 1,2:4,5-di-O-isopropylidene-myo-inositol (6), 3,4,5,6-tetra-O-acetyl-1,2-O-isopropylidene-myo-inositol (7), 3,4,5,6-tetra-O-acetyl-myo-inositol (8), 1,2-O-isopropylidene-3,6-di-O-tosyl-myo-inositol (9), 1,2-O-isopropylidene-3,4,6-tri-O-tosyl-myo-inositol (10), 1,2:4,5-di-O-isopropylidene-3-O-tosyl-myo-inositol (11), 3,6-di-O-benzyl, 1,2:4,5-di-O-isopropylidene-myo-inositol (12), 3,6-di-O-benzyl-1,2-O-isopropylidene-myo-inositol (13), 3,6-di-O-benzyl-myo-inositol (14), 1,2-O-cyclohexylidene-myo-inositol (15), 1,2:4,5-di-O-cyclohexylidene-myo-inositol (16), 1,2:5,6-di-O-cyclohexylidene-myo-inositol (17), 1,3,5-O-(orthoformate)-myo-inositol (18) and 2-benzyl-1,3,5-O-(orthoformate)-myo-inositol (19). The X-ray diffraction structure of compounds 2, 6-8, 18 and 19 are reported. 相似文献
256.
A sensitive and selective voltammetric method for simultaneous determination of Sb(III) and Mo(VI) using Quercetin (Q) as complexing agent is described. Optimal conditions were found to be: pH 3.7, CQ=6.0 µmol L?1 and Eacc=?0.10 V. The LOD (3σ) for Sb(III) are 0.076 and 0.040 µg L?1, whereas for Mo(VI) are 0.086 and 0.048 µg L?1 with tacc of 60 and 120 s, respectively. The method was validated using synthetic sea water (ASTM D665) and was applied to the determination of Sb(III) and Mo(VI) in natural waters with satisfactory results. 相似文献
257.
A general theory of limit orders for ideals of multilinear forms is developed. We relate the limit order of an ideal to those
of its maximal hull and its adjoint ideal. We study the limit orders of the ideals of dominated and multiple summing multilinear
forms. Finally, estimates of the diagonal of a (non-necessarily diagonal) multilinear form are presented, in terms of the
limit order of the ideals to which it belongs.
The third author was supported by the MCYT and FEDER Project BFM2002-01423 and grant GV-GRUPOS04/45. The first and second
authors were supported by CONICET-PIP 5272. The first author was also supported by UBACyT-X108 and ANPCyT-PICT 0315033. 相似文献
258.
I. V. Ajinenko Yu. A. Belokopytov H. Bialkowska H. Boettcher F. Botterweck P. V. Chliapnikov F. Crijns A. De Roeck E. A. De Wolf K. Dziunikowska A. Eskreys W. Friebel Z. C. Garutchava G. V. Gevorkyan H. Graessler P. van Hal T. Haupt Z. A. Kirakosyan W. Kittel J. M?kel? F. Meijers A. B. Michalowska V. I. Nikolaenko L. C. S. Oliveira K. Olkiewicz L. P. Petrovikh V. M. Ronjin A. M. Rybin H. M. T. Saarikko W. Schmitz L. Scholten N. N. Sotnikova O. G. Tchikilev L. A. Tikhonova A. G. Tomaradze V. A. Uvarov F. Verbeure R. Wischnewski Y. V. Yarba EHS-NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,43(1):15-23
Data on the reactions (K +/π+)p→(K +/π+)pπ+π- and (K +/π+)p→(K +/π+)p2π+2π-, obtained with the European Hybrid Spectrometer, are presented and compared with data at lower energies. The contribution of beam and target diffractive dissociation and double Pomeron exchange, and porperties of these reactions are discussed. 相似文献
259.
Ricardo J Cassella Ver?nica A Salim Salvador Garrigues Ricardo E Santelli Miguel de la Guardia 《Analytical sciences》2002,18(11):1253-1256
This paper reports on a new strategy for the slurry sampling determination of dithiocarbamate pesticide zineb [[ethylenebis(dithiocarbamato)]zinc] employing a FIA system with a flame atomic absorption spectrometry detector. In the flow system, an on-line alkaline hydrolysis of the pesticide is performed, allowing the release of Zn(II) ions to the solution, which are easily detected by a flame AAS technique. Several parameters that could affect the performance of the analytical methodology were studied, such as the concentration of NH3(aq) used in the hydrolysis step, the effect of the presence of Triton X-100 on the sensitivity and precision, and the FIA parameters (carrier flow rate and mixing coil volume). Under optimized conditions, aqueous slurries containing 2.5 to 25 microg ml(-1) zineb provided good linear calibration fits. From the obtained data, a detection limit (3sigma) of 1.0 microg ml(-1) zineb was found and a repeatability of 2.7% was obtained from 12 measurements of a slurry containing 2.5 microg m(-1) zineb. On the other hand, a precision (reproducibility) of 7.8% was achieved from three determinations of a sample containing 128 mg g(-1) of the pesticide. Also, the developed system provides a sampling frequency of 72 h(-1). 相似文献
260.
Faraldos JA Antonczak AK González V Fullerton R Tippmann EM Allemann RK 《Journal of the American Chemical Society》2011,133(35):13906-13909
Stabilization of the reaction intermediate eudesmane cation (3) through interaction with Trp 334 during catalysis by aristolochene synthase from Penicillium roqueforti was investigated by site-directed incorporation of proteinogenic and non-canonical aromatic amino acids. The amount of germacrene A (2) generated by the mutant enzymes served as a measure of the stabilization of 3. 2 is a neutral intermediate, from which 3 is formed during PR-AS catalysis by protonation of the C6,C7 double bond. The replacement of Trp 334 with para-substituted phenylalanines of increasing electron-withdrawing properties led to a progressive accumulation of 2 that showed a good correlation with the interaction energies of simple cations such as Na(+) with substituted benzenes. These results provide compelling evidence for the stabilizing role played by Trp 334 in aristolochene synthase catalysis for the energetically demanding transformation of 2 to 3. 相似文献