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301.
Jong Hwa Jung Jeong Ah Rim Soo Jin Lee Naohiro Kameda Toshimi Shimizu 《Tetrahedron》2007,63(31):7449-7456
Asymmetric bolaamphiphilic sugar-based hydrogelators (1-3) were synthesized and their gelation ability with and without alkylammonium ions was investigated by CD, TEM, FTIR and NMR. These compounds acted as versatile gelators for organic solvents and water. The xerogels 1-3 obtained from water showed well-developed structures of fibrils with diameters of 10-38 nm and length of several hundred micrometers. Particularly, the gelation ability of crown-appended gelator 1 was drastically enhanced by addition of alkylammonium ions 4 and 5, suggesting that the bridging effect of alkyldiammonium ions could be the primary driving-force for the stabilization due to the intermolecular hydrogen bonding and electrostatic interactions. The present result is a rare case of a hydrogel being stabilized by a host-guest interaction. In addition, the hydrogel 1 with AgNO3 and KClO4 induced the formation of nanotubular and vesicular structures of silica by sol-gel polymerization of TEOS, respectively. These results indicate that hydrogel 1 acted as a template to produce inorganic nanomaterials. 相似文献
302.
Ah. Dhahri E. Dhahri E. K. Hlil 《Applied Physics A: Materials Science & Processing》2014,116(4):2077-2085
The effect of Cr doping on the structural, magnetic and magnetocaloric properties of perovskite manganites La0.75Sr0.25Mn1–x Cr x O3 (x = 0.15, 0.20, and 0.25) has been investigated. Crystalline structure and magnetic properties are investigated by using X-ray powder diffraction and magnetization measurements, respectively. All samples show a single phase and are found to crystallize in the distorted rhombohedral system with \( R\overline{3} \,c \) space group. A monotonous change of Curie temperature (T C), from 314 to 253 K, is observed when content doping increases. Substantial magnetic entropy change reaching 4.20 J/kg K is revealed. Relative cooling power was estimated as well. It was found to reach 289, 323, and 386 J/kg for x = 0.15, 0.20, and 0.25, respectively. Field dependence of the magnetic entropy change showing the power law dependence \( \Delta S_{\rm M} \propto \,\,\left( {\mu_{ 0} \rm H} \right)^{n} \) is also analyzed and discussed. 相似文献
303.
Jeong S Won N Lee J Bang J Yoo J Kim SG Chang JA Kim J Kim S 《Chemical communications (Cambridge, England)》2011,47(28):8022-8024
A new multiplexed NIR in vivo imaging is showcased by using quantum dots and NaYF(4):Yb(3+),Tm(3+) nanoparticles. The 'temporal' multiplexing is demonstrated by alternating the excitation wavelengths and unmixing the emissions of different probes. Multiplexed cellular imaging and the cellular trafficking in animal models are shown. 相似文献
304.
Voranuch Somsongkul Felix Lang Ah Reum Jeong Marin Rusu Marisa Arunchaiya Thomas Dittrich 《固体物理学:研究快报》2014,8(9):763-766
Modulated charge separation across (MO)/CH3NH3PbI3 and (MO)/PbI2/CH3NH3PbI3 (MO = TiO2, MoO3) interfaces was investigated by surface photovoltage (SPV) spectroscopy. Perovskite layers were deposited by solution‐based one‐step preparation and two‐step preparation methods. An unreacted PbI2 layer remained at the interface between the metal oxide and CH3NH3PbI3 for two‐step preparation. For the two‐step preparation on TiO2, the SPV signal related to absorption in CH3NH3PbI3 increased in comparison to the one‐step preparation due to electron transfer from CH3NH3PbI3 via PbI2 into TiO2 whereas the SPV signal related to defect transitions decreased. For the one‐step preparation on MoO3, holes photogenerated in CH3NH3PbI3 recombined with electrons in MoO3. In contrast, a hole transfer from CH3NH3PbI3 towards MoO3 was blocked by the PbI2 interlayer for the two‐step preparation on MoO3. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
305.
Sang-Han Lee Sun Ah Lee Jong Man Lee Tae Soon Park K. B. Lee 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):721-725
137Cs was measured in soil samples collected in Korea from 2006 to 2008 using a low-level background gamma-ray spectrometer that was designed and developed by KRISS (Korea Research Institute of Standards and Science). The objectives of this study are to evaluate the newly developed low-level background gamma-ray spectrometer and, consequently, to provide information on the horizontal and vertical distribution of 137Cs in Korean soil. 137Cs concentrations in surface soil varied from 12.8 ± 0.9 to 108 ± 4 Bq kg?1, and the vertical profiles of 137Cs from the Nari basin in Ulleung Island in the East Sea/Sea of Japan and Seongsan Ilchulbong Peak, Jeju Island, showed a higher concentration in the surface layer that gradually decreased with depth. On the other hand, the 137Cs concentration in soil samples collected from Bukhan Mountain National Park in Seoul showed a subsurface maximum and decreased with depth. The 137Cs inventories in the soil column were calculated to be 1,830–4,360 Bq m?2 with a mean of 2,770 Bq m?2, which was the same order of magnitude as the global fallout inventories in the mid-latitude region of the Northern Hemisphere. 相似文献
306.