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1.
Anette Munch Elmr Patric Jannasch 《Journal of polymer science. Part A, Polymer chemistry》2006,44(7):2195-2205
Methacrylate‐functionalized poly(ethylene oxide‐co‐ethylene carbonate) macromonomers were prepared in two steps by the anionic ring‐opening polymerization of ethylene carbonate at 180 °C, with potassium methoxide as the initiator, followed by the reaction of the terminal hydroxyl groups of the polymers with methacryloyl chloride. The molecular weight of the polymer went through a maximum after approximately 45 min of polymerization, and the content of ethylene carbonate units in the polymer decreased with the reaction time. A polymer having a number‐average molecular weight of 2650 g mol?1 and an ethylene carbonate content of 28 mol % was selected and used to prepare a macromonomer, which was subsequently polymerized by UV irradiation in the presence of different concentrations of lithium bis(trifluoromethanesulfonyl)imide salt. The resulting self‐supportive crosslinked polymer electrolyte membranes reached ionic conductivities of 6.3 × 10?6 S cm?1 at 20 °C. The coordination of the lithium ions by both the ether and carbonate oxygens in the polymer structure was indicated by Fourier transform infrared spectroscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2195–2205, 2006 相似文献
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Mikkelsen LM Hernáiz MJ Martín-Pastor M Skrydstrup T Jiménez-Barbero J 《Journal of the American Chemical Society》2002,124(50):14940-14951
The conformational properties of the C-glycosyl analogue of the core trisaccharide alpha-D-Man-(1 --> 3)-[alpha-D-Man-(1 --> 6)]-D-Man in solution have been carefully analyzed by a combination of NMR spectroscopy and time-averaged restrained molecular dynamics. It has been found that both the alpha-1,3- and the alpha-1,6-glycosidic linkages show a major conformational averaging. Unusual Phi ca. 60 degrees orientations for both Phi torsion angles are found. Moreover, a major conformational distinction between the natural compound and the glycomimetic affects to the behavior of the omega(16) torsion angle around the alpha-1 --> 6-linkage. Despite this increased flexibility, the C-glycosyl analogue is recognized by three mannose binding lectins, as shown by NMR (line broadening, TR-NOE, and STD) and surface plasmon resonance (SPR) methods. Moreover, a process of conformational selection takes place, so that these lectins probably bind the glycomimetic similarly to the way they recognize the natural analogue. Depending upon the architecture and extension of the binding site of the lectin, loss or gain of binding affinity with respect to the natural analogue is found. 相似文献
4.
Wagner HP Pepich BV Frebis CP Hautman DP Munch DJ Jackson PE 《Journal of chromatographic science》2001,39(6):255-259
The development of the U.S. Environmental Protection Agency (EPA) Method 317.0 is initiated to provide a sufficiently sensitive and fundamental technique for the compliance monitoring of trace levels of bromate in drinking water. After a comparative evaluation of Method 317.0 and elimination of a chlorite interference, this method is tested by a collaborative study in order to determine the precision and bias of the method and evaluate its potential role as a future compliance-monitoring method for inorganic disinfection by-products (DBPs) and trace bromate. This technique provides a practical method for future compliance monitoring for all of the inorganic oxyhalide DBPs including trace concentrations of bromate. 相似文献
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The development of US Environmental Protection Agency (EPA) Method 317.0 provided a more sensitive, acceptable alternative to EPA Method 300.1 to be proposed as one of the recommended compliance monitoring methods for Stage II of the Disinfectants/Disinfection By-Products (DBP) Rule. This work was initiated to evaluate other postcolumn reagents (PCRs) that might be utilized to provide an additional, alternative method in order to augment compliance monitoring flexibility for inorganic oxyhalide DBP anions. Modifications of the method reported by Salhi and von Gunten, which included adjustment and optimization of flow-rates, reaction temperature, and delivery of the PCR, improved the method performance. Method 326.0 incorporates an acidic solution of potassium iodide containing catalytic amounts of molybdenum(VI) as the PCR and provides acceptable precision and accuracy for all analytes and a postcolumn bromate detection limit in reagent water of 0.17 microg/l. 相似文献
6.
W. Meysahn F. Löwe G. A. Shook R. C. Emmons J. C. Munch H. G. Fisk J. E. Verschaffelt R. Crombez und G. Kortiim 《Fresenius' Journal of Analytical Chemistry》1931,85(1-3):64-67
Ohne Zusammenfassung 相似文献
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Consider a Hilbert space
equipped with a time-structure, i.e., a resolution E of the identity on
defined on subsets of some linearly ordered set Λ. For which x and y in
is it possible to find a causal (time respecting) compact operator T, so that Tx = y? When T is required to be a Hilbert-Schmidt operator and (Λ, E) is sufficiently regular, this question is answered in terms of the “time-densities” of x and y. The condition is that the integral ∝gLμx({s t})−1 dμy(t) should be finite, where μx and μy are the measures on Λ given by μx(Ω) = ¦|E(Ω)x¦|2 and μy(Ω) = ¦|E(Ω)y¦|2. Further a solution is given for the related problem of minimizing the sum of ¦|Tx − y¦|2 and the squared Hilbert-Schmidt norm ¦|R¦|22 of T. 相似文献
9.
Munch HK Heide ST Christensen NJ Hoeg-Jensen T Thulstrup PW Jensen KJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(26):7198-7204
Self-assembly of proteins mediated by metal ions is crucial in biological systems and a better understanding and novel strategies for its control are important. An abiotic metal ion ligand in a protein offers the prospect of control of the oligomeric state, if a selectivity over binding to the native side chains can be achieved. Insulin binds Zn(II) to form a hexamer, which is important for its storage in vivo and in drug formulations. We have re-engineered an insulin variant to control its self-assembly by covalent attachment of 2,2'-bipyridine. The use of Fe(II) provided chemoselective binding over the native site, forming a homotrimer in a reversible manner, which was easily followed by the characteristic color of the Fe(II) complex. This provided the first well-defined insulin trimer and the first insulin variant for which self-assembly can be followed visually. 相似文献
10.
The aqueous solution chemistry of niobium is rather unexplored, and well characterized aqua complexes are scarce. In this work, a new niobium aqua ion is obtained upon treatment of Zn-reduced ethanolic solutions of NbCl5 with HCl in the presence of a sulfide source. The red aqua ion, obtained upon cation-exchange chromatography, forms readily the thiocyanate complex which has been crystallized as Cs(4.26)Na(1.74)[Nb4SO5(NCS)10] . 0.33H2O. X-ray crystallography revealed an unprecedented metal-metal bonded tetranuclear Nb4(mu4-S)(mu2-O)5(4+) core with a capping mu4-S ligand. 相似文献