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41.
Polson MI Loiseau F Campagna S Hanan GS 《Chemical communications (Cambridge, England)》2006,(12):1301-1303
The dinuclear ruthenium complex of a large, planar bis-tridentate bridging ligand has been prepared; to the best of our knowledge, this species is the near IR-emitting Ru(II) complex exhibiting the longest-lived emission and highest quantum yield reported so far, due to the dramatic reduction in its radiationless decay rate constant. 相似文献
42.
Howard H. D. Lee Fredrick J. Mc Garry 《Journal of Macromolecular Science: Physics》2013,52(2-3):185-202
Volume recovery in the temperature range of above Tg to below T β has been studied for two atactic polystyrene specimens (M w = 210,000 and 300,000 g/mol). Observations clearly disclose the collapse of free volume even at temperatures well below Tβ. In an excess free volume sufficient environment, as the aging temperature is lowered through Tβ, the retardation of the initial volume recovery becomes progressively longer, forming a variation in the nonlinearity of the isotherms. Indeed, it is this variation that leads to the observation of the β transition in the V-T plot. The β transition is time dependent, but molecular weight independent. On the other hand, in addition to well-known molecular weight and time dependence, the glass transition has another important feature: The difference in thermal expansion coefficients above and below Tg increases slightly with aging time. Thus, time cannot alter the existence of Tg. Consequently, this study favors thermodynamic theories for the formation of Tg. 相似文献
43.
In this paper we present a super-resolved Raman spectroscopy configuration where, due to the proposed resolution improvement, more chemical species can be simultaneously detected. The idea includes usage of the basic property of Raman in which shifting the excitation wavelength will shift the absolute wavelength of the Raman spectral lines. Thus, encoding the spectra prior to analysis by the spectrometer allows obtaining spectral super-resolved sensing via time multiplexing super-resolution concepts applied over the spectral domain. 相似文献
44.
Wu Y Zhou Y Ouari O Woods M Zhao P Soesbe TC Kiefer GE Sherry AD 《Journal of the American Chemical Society》2008,130(42):13854-13855
Linear polymers of PARACEST agents were prepared by using classical free radical chain polymerization conditions. The Eu3+-polymers exhibited similar intermediate-to-slow water exchange and CEST characteristics as the Eu3+-monomers. This provided an avenue to lower the detection limit of these imaging agents substantially and makes them potentially useful as MRI sensors for molecular imaging. 相似文献
45.
Dewberry CT Etchison KC Grubbs Ii GS Powoski RA Serafin MM Peebles SA Cooke SA 《Physical chemistry chemical physics : PCCP》2007,9(44):5897-5901
Hyperfine structures arising from the couplings of the nuclear spin angular momentum of (17)O (I = 5/2) with the end over end rotation of several metal-containing diatomic monoxides have been observed using a Fourier transform microwave spectrometer. The molecules have been produced by reacting (17)O(2) with laser ablated metal atoms. The oxygen-17 nuclear quadrupole coupling constants have been determined for the title molecules and are interpreted in terms of a simple Townes-Dailey model. Also, the oxygen-17 nuclear spin-rotation constants have been determined and used to calculate the oxygen-17 shieldings for each molecule. 相似文献
46.
This tutorial review consists of five main sections. The first gives a general introduction and then a discussion about the need for luminescent assemblies. The next four sections present the various assemblies based on the metal ions used to assemble the final structures. Each of these sections gives a brief overview of the design principles, synthesis, and ground and excited-state properties of the ligands and complexes in question. The review concludes with some suggestions for future avenues of research. 相似文献
47.
Chariya Chao Waraporn Pratchayawutthirat Piyasan Praserthdam Takeshi Shiono Garry L. Rempel 《Macromolecular rapid communications》2002,23(12):672-675
For the copolymerization of ethylene with propylene or a higher α‐olefin, using Et[Ind]2ZrCl2 metallocene catalyst, modification of silica with silicon tetrachloride prior to MAO adsorption can increase the activity, which is more pronounced for ethylene/1‐hexene copolymerization at higher pressure and temperature. The molecular weight of the copolymer produced was lower and the polydispersity tends to be decreased. No significant effect of SiCl4 addition on the microstructure and the chemical composition distribution of the copolymer produced was observed. 相似文献
48.
Jung Dae Kim Joo B. P. Soares Garry L. Rempel 《Journal of polymer science. Part A, Polymer chemistry》1999,37(3):331-339
Tailoring of the molecular weight distribution (MWD) in ethylene polymerization was attempted by selectively combining different types of metallocene catalysts onto a single support. The catalyst produced by supporting Et[Ind]2ZrCl2 and Cp2HfCl2 onto a single MAO pretreated silica support was able to produce polymers with unimodal or bimodal MWD's. This approach permits the synthesis of polyethylene with different MWD's using the same catalyst as a function of the polymerization conditions. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 331–339, 1999 相似文献
49.
Kieran F. Scott Timothy J. Mann Shadma Fatima Mila Sajinovic Anshuli Razdan Ryung Rae Kim Adam Cooper Aflah Roohullah Katherine J. Bryant Kasuni K. Gamage David G. Harman Fatemeh Vafaee Garry G. Graham W. Bret Church Pamela J. Russell Qihan Dong Paul de Souza 《Molecules (Basel, Switzerland)》2021,26(23)
Phospholipase A2 (PLA2) enzymes were first recognized as an enzyme activity class in 1961. The secreted (sPLA2) enzymes were the first of the five major classes of human PLA2s to be identified and now number nine catalytically-active structurally homologous proteins. The best-studied of these, group IIA sPLA2, has a clear role in the physiological response to infection and minor injury and acts as an amplifier of pathological inflammation. The enzyme has been a target for anti-inflammatory drug development in multiple disorders where chronic inflammation is a driver of pathology since its cloning in 1989. Despite intensive effort, no clinically approved medicines targeting the enzyme activity have yet been developed. This review catalogues the major discoveries in the human group IIA sPLA2 field, focusing on features of enzyme function that may explain this lack of success and discusses future research that may assist in realizing the potential benefit of targeting this enzyme. Functionally-selective inhibitors together with isoform-selective inhibitors are necessary to limit the apparent toxicity of previous drugs. There is also a need to define the relevance of the catalytic function of hGIIA to human inflammatory pathology relative to its recently-discovered catalysis-independent function. 相似文献
50.
Anna S. Gardberg Brian S. Potter Rex A. Palmer Garry J. McIntyre Dean A. A. Myles 《Journal of chemical crystallography》2011,41(4):470-480