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991.
Christian Schramm Beate Rinderer Richard Tessadri Heinz Duelli 《Journal of Sol-Gel Science and Technology》2010,53(3):579-586
Based on differential scanning calorimetry data, it was shown that the reaction of (3-triethoxysilylpropyl)succinic anhydride
and (3-amino)propyltriethoxysilane at 110 °C resulted in the formation of polyamic acid, whereas the thermal treatment at
220 °C led to the generation of an aliphatic monoimide-bridged polysilsesquioxane as proved by FT-IR. X-ray powder diffraction
studies showed a prominent reflection at 2θ = 6.66° (d = 1.32 nm) revealing that a crystalline area is formed. 29Si CP-MAS-NMR and 13C CP-TOSS-MAS-NMR measurements proved that no cleavage of the Si–C bond occurred, and a highly condensed material was obtained. 相似文献
992.
Sun Hwa Lee Daniel R. Dreyer Jinho An Aruna Velamakanni Richard D. Piner Sungjin Park Yanwu Zhu Sang Ouk Kim Christopher W. Bielawski Rodney S. Ruoff 《Macromolecular rapid communications》2010,31(3):281-288
A method for growing polymers directly from the surface of graphene oxide is demonstrated. The technique involves the covalent attachment of an initiator followed by the polymerization of styrene, methyl methacrylate, or butyl acrylate using atom transfer radical polymerization (ATRP). The resulting materials were characterized using a range of techniques and were found to significantly improve the solubility properties of graphene oxide. The surface‐grown polymers were saponified from the surface and also characterized. Based on these results, the ATRP reactions were determined to proceed in a controlled manner and were found to leave the structure of the graphene oxide largely intact.
993.
994.
995.
Graeme J. Gainsford Richard H. Furneaux Peter C. Tyler Anthony Sauve Vern L. Shramm 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(3):m65-m68
The sodium salt of [immucillin‐A–CO2H]− (Imm‐A), namely catena‐poly[[[triaquadisodium(I)](μ‐aqua)[μ‐(1S)‐N‐carboxylato‐1‐(9‐deazaadenin‐9‐yl)‐1,4‐dideoxy‐1,4‐imino‐d ‐ribitol][triaquadisodium(I)][μ‐(1S)‐N‐carboxylato‐1‐(9‐deazaadenin‐9‐yl)‐1,4‐dideoxy‐1,4‐imino‐d ‐ribitol]] tetrahydrate], {[Na2(C12H13N4O6)2(H2O)7]·4H2O}n, (I), forms a polymeric chain via Na+—O interactions involving the carboxylate and keto O atoms of two independent Imm‐A molecules. Extensive N,O—H...O hydrogen bonding utilizing all water H atoms, including four waters of crystallization, provides crystal packing. The structural definition of this novel compound was made possible through the use of synchrotron radiation utilizing a minute fragment (volume ∼2.4 × 10−5 mm−3) on a beamline optimized for protein data collection. A summary of intra‐ring conformations for immucillin structures indicates considerable flexibility while retaining similar intra‐ring orientations. 相似文献
996.
Daniella Morgos Ivan Geroy Richard G. Sevier Molly M. Gribb Kevin P. Ryan Herbert H. Hill 《International Journal for Ion Mobility Spectrometry》2010,13(1):1-7
An ion mobility spectrometer (IMS) probe system for real-time, subsurface soil-gas sampling applications is presented. The
system includes an IMS and supporting electronics encased in a 51 mm diameter stainless steel probe housing. The IMS was challenged
in the laboratory with 2,6-di-tert-butylpyridine (DtBP) and tetrachloroethylene (PCE) in zero air yielding reduced ion mobility
constants (Ko) values of 1.42 cm2/Vs (n = 3) and 1.79 ± 0.01 cm2/Vs (n = 3), respectively. A resolving power of 38 and 31 was obtained for DtBP and PCE, respectively. The system was deployed at
a PCE-contaminated site to demonstrate its performance under field conditions. PCE was detected in the vapor samples as evidenced
by peaks with a Ko value of 1.80 ± 0.01 cm2/Vs for two measurements that were taken 6 min apart. The presence of PCE at the contaminated site was confirmed by GC-MS
analysis of a gas sample at an EPA-certified laboratory, suggesting that this IMS system can be used to detect PCE under field
conditions. 相似文献
997.
V. Costa K. Leyssens A. Adriaens N. Richard F. Scholz 《Journal of Solid State Electrochemistry》2010,14(3):449-451
The characterization of materials constituting cultural artefacts is a challenging step in their conservation, due to the object’s uniqueness and the reduced number of conservation institutes able to supply non-destructive analysis. We propose an alternative analytical tool, which combines accessibility (low cost and portable) and high sensitivity, based on electrochemical linear sweep voltammetry (LSV) with paraffin impregnated graphite electrode (PIGE). To investigate the composition of “white alloys” that certainly have been used as decoration on copper-based Roman fibulae, sampling was done very locally by gently rubbing the selected areas with the PIGE. LSV results evidence the presence of silver, lead, and tin, supporting the argument provided by typological analysis that these metals were used for decoration. 相似文献
998.
Ming-Lai Fu Norma L. Rangel Richard D. Adams Jorge M. Seminario 《Journal of Cluster Science》2010,21(4):867-878
Abstract
Thiacalix[4]arenes are a unique family of polydentate ligands that offer a combination of four soft sulfur atoms together with four hard phenol oxygen atoms for binding to metal ions. In this study, the tetranuclear cadmium (II) complex Cd4II(tca)2·1.5CH2Cl2 (tca4− = tetra-anionic p-tert-butylthiacalix[4]arene) (1) was synthesized by reaction of a deprotonated p-tert-butylthiacalix[4]arene and various CdII salts. The structure of 1 was established by single crystal X-ray diffraction analysis. The neutral complex 1 contains a square arrangement of four cadmium (II) ions sandwiched between two tca4− ligands that have a ‘cone’ conformation similar to that of the free ligand. The absorption and emission properties of the free ligand H4tca and complex 1 have been recorded and explained by DFT calculations of the molecular orbitals and electronic transitions between them. 相似文献999.
Richard Law Oliver Barker John J. Barker Thomas Hesterkamp Robert Godemann Ole Andersen Tara Fryatt Steve Courtney Dave Hallett Mark Whittaker 《Journal of computer-aided molecular design》2009,23(8):459-473
Fragment-based drug discovery (FBDD) represents a change in strategy from the screening of molecules with higher molecular
weights and physical properties more akin to fully drug-like compounds, to the screening of smaller, less complex molecules.
This is because it has been recognised that fragment hit molecules can be efficiently grown and optimised into leads, particularly
after the binding mode to the target protein has been first determined by 3D structural elucidation, e.g. by NMR or X-ray
crystallography. Several studies have shown that medicinal chemistry optimisation of an already drug-like hit or lead compound
can result in a final compound with too high molecular weight and lipophilicity. The evolution of a lower molecular weight
fragment hit therefore represents an attractive alternative approach to optimisation as it allows better control of compound
properties. Computational chemistry can play an important role both prior to a fragment screen, in producing a target focussed
fragment library, and post-screening in the evolution of a drug-like molecule from a fragment hit, both with and without the
available fragment-target co-complex structure. We will review many of the current developments in the area and illustrate
with some recent examples from successful FBDD discovery projects that we have conducted. 相似文献
1000.
Kwok RK Linet MS Chodick G Kleinerman RA Freedman DM Fears T Johnson RE Alexander BH 《Photochemistry and photobiology》2009,85(1):45-49
Skin cancer studies depend on questionnaires to estimate exposure to ultraviolet light and subsequent risk but are limited by recall bias. We investigate the feasibility of developing a short checklist of categories comprising outdoor activities that can improve sun exposure questionnaires for use in epidemiologic studies. We recruited 124 working and retired U.S. radiologic technologists (52% women). Each subject was instructed to complete a daily activity diary, listing main indoor and outdoor activities between 9:00 A.M. and 5:00 P.M. during a 7 day period. A total of 4697 entries were associated with 1408 h (21.1%) of the total 6944 h spent outdoors. We were able to classify the activities into seven main activity categories: driving, yard work, home-maintenance, walking or performing errands, water activities, other recreational or sports activities and leisure activities or relaxing outside. These activities accounted for more than 94% of time spent outdoors both for working and retired men and women. Our data document the feasibility and guidance for developing a short checklist of outdoor activities for use in epidemiologic questionnaires for estimating sunlight exposures of working and retired indoor workers. 相似文献