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21.
Sébastien Bau Denis Bémer Florence Grippari Jean-Christophe Appert-Collin Dominique Thomas 《Journal of nanoparticle research》2014,16(10):1-13
The cysteamine-modified hyaluronic acid (HA) polymer was employed to coat quantum dots (QDs) through a convenient one-step reverse micelle method, with the final QDs hydrodynamic size of around 22.6 nm. The HA coating renders the QDs with very good stability in PBS for more than 140 days and resistant to large pH range of 2–12. Besides, the HA-coated QDs also show excellent fluorescence stability in BSA-containing cell culture medium. In addition, the cell culture assay indicates no significant cytotoxicity for MD-MB-231 breast cancer cells, and its targeting ability to cancer receptor CD44 has been demonstrated on two breast cancer cell lines. The targeting mechanism was further proved by the HA competition experiment. This work has established a new approach to help solve the stability and toxicity problems of QDs, and moreover render the QDs cancer targeting property. The current results indicate that the HA polymer-coated QDs hold the potential application for both in vitro and in vivo cancer imaging researches. 相似文献
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23.
Reactivities of mixed organozinc and mixed organocopper reagents. Part 13 Kinetic study for phosphine‐catalyzed acylation of alkylarylzincs and effect of residual group on the transfer rate of alkyl group 下载免费PDF全文
Özgen Ömür Pekel 《Journal of Physical Organic Chemistry》2016,29(4):190-195
Kinetics of reactions of di‐n‐butylzinc, n‐Bu2Zn, and mixed n‐butyl(substituted phenyl)zinc reagents and n‐Bu(functional group (FG)?C6H4)Zn with benzoyl chloride in the presence of tri‐n‐butylphosphine have been investigated. Reaction rates of transferable n‐butyl group have been determined in tetrahydrofuran at 0 °C to compare the transfer rate of n‐butyl group in homo and mixed diorganozincs. Rate law is consistent with a third‐order reaction, which is first order in diorganozinc, benzoyl chloride, and n‐Bu3P, and a mechanism was proposed. The lower reaction rate of n‐BuPhZn than that of n‐Bu2Zn and negative reaction constant in Hammett plot are in accordance with the carbanionic charge of transferable n‐butyl group in the acylation reaction. These findings support the hypothesis that the reaction rate of transferable group, RT, changes depending upon the residual group, RR, in RRRTZn reagents. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
24.
Yusuf Öztürk Asım Egemen Yılmaz Evrim Çolak Ekmel Özbay 《Photonics and Nanostructures》2012,10(4):624-631
Planar metamaterials, which have incident to normal plane excitation unlike SRR-type structures and that are easily fabricated in multilayer form, have received great interest in recent years. In this paper, one-dimensional and polarization independent circular fishnet metamaterials and their equivalent discontinuous slab-pair modeling for tuning resonance frequencies are introduced. After the numerical and experimental demonstration of the inclusions, the standard retrieval characterization methods and the correspondent/related backward-wave propagation observation are realized in order to check the physical explanation mentioned in the paper. In addition, a detailed phase analysis is performed in order to demonstrate the application of the suggested structure as a phase compensator. 相似文献
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M. Isakov J. Kokkonen K. Östman V.-T. Kuokkala 《The European physical journal. Special topics》2016,225(2):231-242
In this paper, methods to produce rapid strain rate changes for strain rate sensitivity measurements in Split Hopkinson Bar arrangements are presented and discussed. Two different cases are considered: a strain rate change test within the high strain rate region in compression, and a tension test incorporating a large strain rate jump directly from the low strain rate region to high strain rates. The former method is based on the loading wave amplitude manipulation, while the latter method is based on the incorporation of a low strain rate loading device into a Tensile Split Hopkinson Bar apparatus. 相似文献
28.
J. C. Van't Spijker P. Dorenbos J. T. M. De Haas C. W. E. Van Eijk H. U. Güdel K. Krmer 《Radiation measurements》1995,24(4):379-381
In this work we present the scintillation properties of K2LaCl5 doped with Ce3+ concentrations of 0, 0.1, 1 and 10%. Under X-ray excitation the crystals show the efficient Ce3+ (5d–4f) luminescence between 340 and 400 nm. Depending on the Ce concentration, the light yields vary between 24,000 and 50,000 photons/MeV (ph/MeV). Experiments with 662 KeV gamma ray excitation show light yields varying between 13,000 and 30,000 ph/MeV. For Ce luminescence a single exponential decay time of approximately 40 ns is expected. However, for K2LaCl5:10%Ce, the decay is not single exponential. As a function of the time t, it can be described by a 1/t1.63 behaviour for large t. With a crystal of K2LaCl5:10%Ce we obtained an energy resolution of 5.1% for 662 KeV gamma ray excitation of 137Cs. 相似文献
29.
T. Ludziejewski T. Stöhlker S. Keller H. Beyer F. Bosch O. Brinzanescu C. Kozhuharov A. Krämer D. Liesen P.H. Mokler R.H. Pratt P. Rymuza C.D. Shaffer Z. Stachura P. Świat A. Warczak 《Hyperfine Interactions》1998,114(1-4):165-169
Electron bremsstrahlung has been investigated for collisions of 223.2 MeV/amu He-like uranium ions with N2 and Ar gaseous targets. The doubly differential cross-sections for bremsstrahlung are compared to the predictions of relativistic
first order Born calculations (Bethe-Heitler formula with Elwert correction factor) and to the calculations based on the exact
wavefunctions for electrons moving in the external point-Coulomb potential of the projectile. Whereas the “exact” IPA calculations
give an improved agreement with experimental data, as compared to the Bethe-Heitler theory, in particular at the end-point
region of the bremsstrahlung spectra, discrepancies still remain at lower photon energies.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
30.
We have examined a solution to the FRW model of the Einstein and de Sitter Universe, often termed the standard model of cosmology, using wide values for the normalized cosmic constant (Ω∧) and spacetime curvature (Ω
k
) with proposed values of normalized matter density. These solutions were evaluated using a combination of the third type of elliptical equations and were found to display critical points for redshift z, between 1 and 3, when Ω∧ is positive. These critical points occur at values for normalized cosmic constant higher than those currently thought important, though we find this solution interesting because the Ω∧ term may increase in dominance as the Universe evolves bringing this discontinuity into importance. We also find positive Ω∧tends towards attractive at values of z which are commonly observed for distant galaxies. 相似文献