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951.
Daniel Nystrm Per Antoni Eva Malmstrm Mats Johansson Michael Whittaker Anders Hult 《Macromolecular rapid communications》2005,26(7):524-528
Summary: Organic‐inorganic hybrid materials consisting of nanosized silica particles with surface grafted PS or PS‐b‐PMMA were synthesized using ATRP. These hybrid materials were used in the fabrication of highly‐ordered isoporous membranes. Optical characterization revealed that the membranes consisted of hexagonally ordered pores of uniform size. The combination of an open pore structure and high surface area makes isoporous membranes into materials of high interest in fields as biotechnology and photonics.
952.
L. Degiorgi F.B.B. Anders G. Grüner 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):167-170
We show that the optical response of metals with strong electron-electron correlation consists of two excitations, a renormalized
Drude response at zero energy and a mid-infrared peak occurring at frequencies around 2000 cm-1. The latter originates from a dynamical, correlation-induced gap, as evinced from a many body theoretical approach based
on the periodic Anderson model. At very low temperatures, it can be viewed as optical gap between two renormalized quasi-particle
bands. The gap size is proportional to the geometric mean of the characteristic lattice Kondo temperature of the material
and its bandwidth.
Received 28 August 2000 and Received in final form 31 October 2000 相似文献
953.
Dr. Abdul Malik Puthan Peedikakkal Hasan Al-Mohsin Dr. Almaz Jalilov Prof. Theis I. Sølling Dr. Anders B. Skov 《Chemphyschem》2021,22(11):1088-1093
Polymorphic salts of trans-1,2-bis(4-pyridyl)ethylene (bpe), 2 [bpeH2] ⋅ (SO4)(2HSO4) ( 1 ) and [bpeH2] ⋅ 2HSO4 ( 2 ) have been synthesized and their structures determined by X-ray crystallography. The Schmidt postulate predicts that neither of the salts will give rise to photodimerization so they can both potentially be applied as green light emitters. Despite the predictions, 1 undergoes a stereospecific solid-state photodimerization reaction with 100 % yield. This is due to UV induced combination of sliding and pedal-like movement of the pyridyl ring system that influences the alignment of C=C bonds. The sliding motion is restricted in 2 . Consequently, the green emission from 1 is completely quenched after photodimerization. It is evident that counter ions play a dominant role in dis- and enabling photodimerization; their degree of protonization and lattice placement are important solvent controlled design parameters towards crystal structures that can act as future light emitters. 相似文献
954.
955.
D. Lichtblau M. Strli T. Trafela J. Kolar M. Anders 《Applied Physics A: Materials Science & Processing》2008,92(1):191-195
Due to sampling restrictions in the analysis of cultural heritage materials, non-destructive approaches are intensively sought
for. While NIR spectrometry has rarely been used for this purpose due to the complexity of the spectra, chemometric methods
can be used to extract the necessary information. For the purpose of determination of mechanical properties of historical
paper, partial least squares approach was used and it is shown that tensile strength, and tensile strength after folding,
can be estimated based on NIR spectra. As the mechanical properties of paper-based objects define their accessibility, a new
dispersive portable instrument was built, which will enable us to rapidly survey the condition of library and archival collections.
PACS 82.80.Gk; 28.52.Fa; 28.52.Lf 相似文献
956.
K. S. Yeo F. R. Mahamd Adikan M. Mokhtar S. Hitam M. A. Mahdi 《Applied physics. B, Lasers and optics》2013,110(3):353-357
We demonstrate a continuous wave tunable fiber optical parametric oscillator in a Fabry–Perot cavity consisting of a 500-m highly nonlinear fiber. In this work, the pump propagates in both directions together with the signal, thus making full use of its parametric gain. The resultant laser peak power is uneven across the wavelength range of interest due to wavelength-dependent phase modulation by the single-mode fiber sections in the cavity. This can be solved by filtering the idler spectral component from the oscillating cavity. 相似文献
957.
A new pulse sequence for high-resolution T2-weighted (T2-w) imaging is proposed — image domain propeller fast spin echo (iProp-FSE). Similar to the T2-w PROPELLER sequence, iProp-FSE acquires data in a segmented fashion, as blades that are acquired in multiple TRs. However, the iProp-FSE blades are formed in the image domain instead of in the k-space domain. Each iProp-FSE blade resembles a single-shot fast spin echo (SSFSE) sequence with a very narrow phase-encoding field of view (FOV), after which N rotated blade replicas yield the final full circular FOV. Our method of combining the image domain blade data to a full FOV image is detailed, and optimal choices of phase-encoding FOVs and receiver bandwidths were evaluated on phantom and volunteers. The results suggest that a phase FOV of 15–20%, a receiver bandwidth of ± 32–63 kHz and a subsequent readout time of about 300 ms provide a good tradeoff between signal-to-noise ratio (SNR) efficiency and T2 blurring. Comparisons between iProp-FSE, Cartesian FSE and PROPELLER were made on single-slice axial brain data, showing similar T2-w tissue contrast and SNR with great anatomical conspicuity at similar scan times — without colored noise or streaks from motion. A new slice interleaving order is also proposed to improve the multislice capabilities of iProp-FSE. 相似文献
958.
959.