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61.
High-throughput approaches for the discovery and optimization of new olefin polymerization catalysts
Murphy V Bei X Boussie TR Brümmer O Diamond GM Goh C Hall KA Lapointe AM Leclerc M Longmire JM Shoemaker JA Turner H Weinberg WH 《Chemical record (New York, N.Y.)》2002,2(4):278-289
The discovery of new olefin polymerization catalysts is currently a time-intensive trial-and-error process with no guarantee of success. A fully integrated high-throughput screening workflow for the discovery of new catalysts for polyolefin production has been implemented at Symyx Technologies. The workflow includes the design of the metal-ligand libraries using custom-made computer software, automated delivery of metal precursors and ligands into the reactors using a liquid-handling robot, and a rapid primary screen that serves to assess the potential of each metalligand-activator combination as an olefin polymerization catalyst. "Hits" from the primary screen are subjected to secondary screens using a 48-cell parallel polymerization reactor. Individual polymerization reactions are monitored in real time under conditions that provide meaningful information about the performance capabilities of each catalyst. Rapid polymer characterization techniques support the primary and secondary screens. We have discovered many new and interesting catalyst classes using this technology. 相似文献
62.
Koga T Seo YS Zhang Y Shin K Kusano K Nishikawa K Rafailovich MH Sokolov JC Chu B Peiffer D Occhiogrosso R Satija SK 《Physical review letters》2002,89(12):125506
We report an anomalous swelling of polymer thin films in carbon dioxide (CO(2)) which is associated (in both locus and form) with the density fluctuation ridge that forms along the extension of the coexistence curve of gas and liquid in the P-T phase diagram. Neutron reflectivity results showed that CO(2) could be sorbed to a large extent ( approximately 60%) in thin polymer films even when the bulk miscibility of the polymer with CO(2) is very poor. The anomalous swelling is found to scale with the polymer radius of gyration (R(g)) and extends to a distance approximately 10 R(g). 相似文献
63.
Deepa M. Goli Dennis M. Dishong Craig J. Diamond George W. Gokel 《Tetrahedron letters》1982,23(50):5243-5246
The first compelling evidence for intramolecular sidearm involvement in sodium and potassium cation complexation by carbon-pivot lariat ethers is presented. 相似文献
64.
Aequationes mathematicae - 相似文献
65.
The microwave spectrum of trimethylbromosilane (trimethylsilylbromide) has been investigated in the 26.5–40.0-GHz region. Spectra of several isotopic species have been observed, including the previously unreported spectrum of the 1H12C30Si81Br species, which yielded a B rotational constant of 1440.92 ± 0.02 MHz. From the experimental data it has been possible to derive the following structural parameters: SiBr = 2.235 ± 0.002 Å, SiC = 1.856 ± 0.010 Å, and ∠CSiBr = 107.5 ± 0.1°. The results have been compared to other relevant data and discussed in terms of prevailing chemical bonding principles. 相似文献
66.
Khalil H Mahajan D Rafailovich M Gelfer M Pandya K 《Langmuir : the ACS journal of surfaces and colloids》2004,20(16):6896-6903
Concurrent sonolysis of iron pentacarbonyl and poly(ethylene glycol)-400 (PEG-400) in hexadecane solvent proceeds via zero-order kinetics and results in Fe nanoparticles encapsulated in PEG-400 (Fe-PEG). The transmission electron microscopy images show Fe-PEG consisting of <3 nm Fe particles that are evenly dispersed in the PEG matrix. M?ssbauer and X-ray absorption fine structure/X-ray absorption near-edge structure data reveal an ordered PEG assembly that helps protect the zerovalent Fe core. The Fe nanoparticles in Fe-PEG are superparamagnetic with a magnetization value of 45 emu/g-Fe at 10 KOe. The rheology of the synthesized material shows an unusual increase in viscosity with temperature that is likely due to lower critical saturation temperature phase segregation over 40 degrees C. The low-temperature mobility of the PEG-400 moiety in Fe-PEG would allow facile ligation of the Fe0 core with biologically and chemically active groups. 相似文献
67.
Patwardhan SV Mukherjee N Steintz-Kannan M Clarson SJ 《Chemical communications (Cambridge, England)》2003,(10):1122-1123
Silicon and oxygen are the two most abundant elements in the Earth's crust but despite the vast scientific literature on crystalline and amorphous silica, new chemistries, structures and applications continue to be discovered for compounds formed from these elements--thus we present here for the first time the formation of new amorphous silica structures that were uniquely synthesized by a bioinspired synthetic system. 相似文献
68.
69.
A simple colorimetric technique is implemented in a polymer microfluidic manifold. The simple chemistry aids an uncomplicated microchannel design, which is fabricated by CO(2) laser ablation. Issues such as bonding of multiple layers, alignment of micro-fabricated structures and integration of optical components are addressed. A demonstration of a stopped flow regime in the microfluidic manifold is also presented. 相似文献
70.
N. S. Kelsall C. E. Svensson S. Fischer D. E. Appelbe R. A. E. Austin D. P. Balamuth G. C. Ball J. A. Cameron M. P. Carpenter R. M. Clark M. Cromaz M. A. Deleplanque R. M. Diamond P. Fallon D. F. Hodgson R. V. F. Janssens D. G. Jenkins G. J. Lane C. J. Lister A. O. Macchiavelli C. D. O’Leary D. G. Sarantities F. S. Stephens D. C. Schmidt D. Seweryniak K. Vetter J. C. Waddington R. Wadsworth D. Ward A. N. Wilson A. V. Afanasjev S. Frauendorf I. Ragnarsson 《The European Physical Journal A - Hadrons and Nuclei》2003,20(1):131-132
High-spin states have been studied in 72Kr and 72Br using the 40Ca + 40Ca and 36Ar + 40Ca reactions at 164 and 145 MeV, respectively. The properties and configurations of the high-spin bands observed have been interpreted using unpaired cranked Nilsson-Strutinsky (CNS), and for 72Kr, paired cranked relativistic Hartree-Bogoliubov (CRHB) calculations. In 72Kr a new band has been identified that has the properties expected for the doubly aligned S-band configuration. In 72Br the previously known bands have been extended to higher spin. This has lead to a re-interpretation of the configurations.Received: 31 October 2002, Published online: 24 February 2004PACS:
21.10.Re Collective levels - 23.20.Lv
transitions and level energies - 27.50. + e
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