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排序方式: 共有80条查询结果,搜索用时 531 毫秒
71.
Hyunki Kim Nicholas Hight‐Huf Ji‐Hwan Kang Phoebe Bisnoff Suvin Sundararajan Theo Thompson Michael Barnes Ryan C. Hayward Todd Emrick 《Angewandte Chemie (International ed. in English)》2020,59(27):10802-10806
Functional polymers with sulfobetaine or phosphorylcholine zwitterions as pendent groups are demonstrated as both ligands and host matrices for CsPbBr3 perovskite nanoparticles (PNPs). These polymers produce nanocomposite films with excellent NP dispersion, optical transparency, and impressive resistance to NP degradation upon exposure to water. Multidentate interactions of the zwitterion‐containing copolymers with the PNPs induce dispersed or weakly aggregated nanocomposite morphologies, depending on the extent of zwitterionic functionality in the polymer. Incorporating additional functionality into the polymers, such as benzophenone pendent groups, yields lithographically patternable films, while time‐resolved photoluminescence measurements provide insight into the electronic impact of PNPs in zwitterionic polymer matrices. 相似文献
72.
73.
This paper deals with a bulk input-batch service queueing system and (r,N)-hysteretic control, i.e., under N-policy and r-quorum discipline. The model also includes state dependent service. The goal of such global control is to reduce the waste
of server capacity (r-quorum), an unwanted number of switchovers between idle and busy modes (N-policy), and the queue length (by means of variable service rates). The analysis of the system is based on first excess level
technique developed by the second author. This approach enables the authors to obtain major characteristics for the queueing
process in a closed analytical form.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
74.
The enthalpies of formation of a series of high and low temperature phases in the ternary oxide system LixV2O5 have been determined by solution calorimetry. Samples of the former, α-Li0.04V2O5, β-Li0.30V2O5, β'-Li0.48V2O5 and γ-LiV2O5, were prepared by solid state reaction at 650°C. The ambient temperature materials Li0.1V2O5(I), Li0.45V2O5(II) and Li1.03V2O5(III) were prepared by n-butyl lithiation in hexane. The thermochemistries of the two classes of material were examined and related to structural features and to the observed behaviour of V2O5 as a battery cathode material in lithium cells. 相似文献
75.
Performance parameters for focusing of radial polarization 总被引:1,自引:0,他引:1
Performance parameters are presented for high-aperture radially polarized focusing systems. These can be used for comparing the focusing performance of different optical systems, including the effect of pupil filters. 相似文献
76.
Fagan JA Simpson JR Landi BJ Richter LJ Mandelbaum I Bajpai V Ho DL Raffaelle R Walker AR Bauer BJ Hobbie EK 《Physical review letters》2007,98(14):147402
We report measurements of the full intrinsic optical anisotropy of isolated single-wall carbon nanotubes (SWNTs). By combining absorption spectroscopy with transmission ellipsometry and polarization-dependent resonant Raman scattering, we obtain the real and imaginary parts of the SWNT permittivity from aligned semiconducting SWNTs dispersed in stretched polymer films. Our results are in agreement with theoretical predictions, highlighting the limited polarizability of excitons in a quasi-1D system. 相似文献
77.
We examine the effects of tightly focusing a radially polarized beam with uniform, Gaussian, or Bessel-Gauss pupil functions. The resulting FWHM is smallest for the case of a uniform amplitude profile, while the Bessel-Gauss beam results in the largest FWHM. The uniform amplitude profile also results in an axial field component that increases fastest with increasing NA. The ratio of the axial component to the transverse component is also the greatest for the uniform pupil function. On the other hand, the Bessel-Gauss beam benefits the most from the use of an annulus. 相似文献
78.
Weissman H Shirman E Ben-Moshe T Cohen R Leitus G Shimon LJ Rybtchinski B 《Inorganic chemistry》2007,46(12):4790-4792
We prepared the first sigma-bonded metal complexes of widely utilized organic dyes, perylene tetracarboxylic acid diimides (PDIs). These 1,7-dipalladium PDI complexes were synthesized by C-Br oxidative addition of 1,7-dibromo-N,N'-dicyclohexyl PDI (Br2PDI) to Pd(0) phosphine complexes bearing triphenylphosphine and bischelating 1,2-bis(diphenylphosphino)ethane (dppe). The structures of Pd-PDI complexes were elucidated by single-crystal X-ray analysis. Surprisingly, despite direct attachement of two late transition metal centers, Pd-PDI systems are highly fluorescent (Phi=0.65 and 0.22 for triphenylphosphine and dppe systems, respectively). This is rationalized in terms of weak electronic interactions between the metal centers and PDI pi-system, as revealed by TD-DFT calculations. 相似文献
79.
Grotjahn DB Miranda-Soto V Kragulj EJ Lev DA Erdogan G Zeng X Cooksy AL 《Journal of the American Chemical Society》2008,130(1):20-21
Experiment and theory have been used to study reactive alkyne pi complexes, intermediates in anti-Markovnikov alkyne hydration by CpRu bis(phosphine) catalysts with heterocyclic substituents. Each heterocycle accepts a hydrogen bond from an acetylene C-H, as revealed by NMR coupling constants between alkyne 13C and 1H nuclei as well as between alkyne 13C and pyridine 15N (2hJCN). Moreover, further alkyne transformations occur at temperatures from 50 to 90 degrees C below what is needed to convert a control compound without the heterocycles. 相似文献
80.
Fagan JA Landi BJ Mandelbaum I Simpson JR Bajpai V Bauer BJ Migler K Walker AR Raffaelle R Hobbie EK 《The journal of physical chemistry. B》2006,110(47):23801-23805
Model composites of DNA-wrapped single-wall carbon nanotubes in poly(acrylic acid) are used to evaluate metrics of nanotube dispersion. By varying the pH of the precursor solutions, we introduce a controlled deviation from ideal behavior. On the basis of small-angle neutron scattering, changes in near-infrared fluorescence intensity are strongly correlated with dispersion, while optical absorption spectroscopy and resonant Raman scattering are less definitive. Our results represent the first systematic comparison of currently accepted measures of nanotube dispersion. 相似文献