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991.
Jeong Won Kim Byoungchul Son Hyunung Yu Hyun Min Park Youn‐Seoung Lee 《Surface and interface analysis : SIA》2014,46(3):193-196
A micro‐beam scanning X‐ray photoelectron spectroscopy (XPS) has been utilized to obtain information about the attachment of ligand to nanoparticles in solution by measuring the ligand components relative to nanoparticle components. CdSe/ZnS core/shell nanoparticles capped with three different kinds of ligand molecules are drop‐casted on a substrate and led to dry into self‐agglomerated micropatterns. Those specimens are mapped out by element‐sensitive XPS imaging. The spatial correlation between surface ligand molecules and core nanoparticle atoms is statistically analysed using Pearson correlation function, which provides with a useful assessment of the ligand binding to nanoparticle surfaces. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
992.
Lin Li Haijun Dang Qichu Xu Wengang Jiang Mei Li Jihong Zhang 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(3):789-795
The extraction behavior of Pu(III), Pu(IV), Np(IV) and Np(V) with di(chlorophenyl)-dithiophosphinic acid (DCPDTPA) in toluene from nitric acid solutions was studied systematically. In aqueous solution with high nitric acid concentration, the extraction capability (represented by distribution ratio D) for Pu and Np in different valences with DCPDTPA comes as D Np(IV) > D Pu(IV) > D Np(V) > D Pu(III). A new radiochemical procedure for Np/Pu separation based on DCPDTPA extraction was proposed and tested with simulated samples. The recoveries of Np and Pu are as high as 80 % after the whole separation procedure, with the decontamination factor of trivalent lanthanide fission product element (e.g. Eu) greater than 1.5 × 104. The decontamination factor of Pu–Np is 2.0 × 103, while the decontamination factor of Np–Pu is greater than 4.8 × 103 after additional purification. 相似文献
993.
994.
本文证明了平面上一类自相似集的共形维数为1.此外还证明了这些自相似集与任何Hausdorff维数为1的度量空间都不是拟对称等价的.这表明,对于这些自相似集而言,共形维数定义中的下确界不能达到. 相似文献
995.
Tung YS Vlachos F Feshitan JA Borden MA Konofagou EE 《The Journal of the Acoustical Society of America》2011,130(5):3059-3067
The activation of bubbles by an acoustic field has been shown to temporarily open the blood-brain barrier (BBB), but the trigger cause responsible for the physiological effects involved in the process of BBB opening remains unknown. Here, the trigger cause (i.e., physical mechanism) of the focused ultrasound-induced BBB opening with monodispersed microbubbles is identified. Sixty-seven mice were injected intravenously with bubbles of 1-2, 4-5, or 6-8 μm in diameter and the concentration of 10(7) numbers/ml. The right hippocampus of each mouse was then sonicated using focused ultrasound (1.5 MHz frequency, 100 cycles pulse length, 10 Hz pulse repetition frequency, 1 min duration). Peak-rarefactional pressures of 0.15, 0.30, 0.45, or 0.60 MPa were applied to identify the threshold of BBB opening and inertial cavitation (IC). Our results suggest that the BBB opens with nonlinear bubble oscillation when the bubble diameter is similar to the capillary diameter and with inertial cavitation when it is not. The bubble may thus have to be in contact with the capillary wall to induce BBB opening without IC. BBB opening was shown capable of being induced safely with nonlinear bubble oscillation at the pressure threshold and its volume was highly dependent on both the acoustic pressure and bubble diameter. 相似文献
996.
Under homogeneous uniaxial strains, the Raman 2D band of graphene involving two-phonon double-resonance scattering processes splits into two peaks and they altogether redshift strongly depending on the direction and magnitude of the strain. Through polarized micro-Raman measurements and first-principles calculations, the effects are shown to originate from significant changes in resonant conditions owing to both the distorted Dirac cones and anisotropic modifications of phonon dispersion under uniaxial strains. Quantitative agreements between the calculation and experiment enable us to determine the dominant double-resonance Raman scattering path, thereby answering a fundamental question concerning this key experimental analyzing tool for graphitic systems. 相似文献
997.
Grassberger P Christensen C Bizhani G Son SW Paczuski M 《Physical review letters》2011,106(22):225701
We study four Achlioptas-type processes with "explosive" percolation transitions. All transitions are clearly continuous, but their finite size scaling functions are not entirely holomorphic. The distributions of the order parameter, i.e., the relative size s(max)/N of the largest cluster, are double humped. But-in contrast to first-order phase transitions-the distance between the two peaks decreases with system size N as N(-η) with η>0. We find different positive values of β (defined via (s(max)/N)~(p-p(c))β for infinite systems) for each model, showing that they are all in different universality classes. In contrast, the exponent Θ (defined such that observables are homogeneous functions of (p-p(c))N(Θ)) is close to-or even equal to-1/2 for all models. 相似文献
998.
SmFeO3, a family of centrosymmetric rare-earth orthoferrites, is known to be nonferroelectric. However, we have found that SmFeO3 is surprisingly ferroelectric at room temperature with a small polarization along the b axis of Pbnm. First-principles calculations indicate that the canted antiferromagnetic ordering with two nonequivalent spin pairs is responsible for this extraordinary polarization and that the reverse Dzyaloshinskii-Moriya interaction dominates over the exchange-striction mechanism in the manifestation of the improper ferroelectricity. SmFeO3 further exhibits an interesting phenomenon of spontaneous magnetization reversal at cryogenic temperatures. This reversal is attributed to the activation of the Sm-spin moment which is antiparallel to the Fe-spin moment below ~5 K. 相似文献
999.
The multiwavelength anomalous diffraction (MAD) method is used to determine phase information in x-ray crystallography by employing anomalous scattering from heavy atoms. X-ray free-electron lasers (FELs) show promise for revealing the structure of single molecules or nanocrystals, but the phase problem remains largely unsolved. Because of the ultrabrightness of x-ray FEL, samples experience severe electronic radiation damage, especially to heavy atoms, which hinders direct implementation of MAD with x-ray FELs. Here, we propose a generalized version of MAD phasing at high x-ray intensity. We demonstrate the existence of a Karle-Hendrickson-type equation in the high-intensity regime and calculate relevant coefficients with detailed electronic damage dynamics of heavy atoms. The present method offers a potential for ab initio structural determination in femtosecond x-ray nanocrystallography. 相似文献
1000.