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排序方式: 共有137条查询结果,搜索用时 211 毫秒
71.
72.
Jie Yang Ji‐Inn Song Qiao Song Julia Y. Rho Edward D. H. Mansfield Stephen C. L. Hall Megan Sambrook Feihe Huang Sbastien Perrier 《Angewandte Chemie (International ed. in English)》2020,59(23):8860-8863
Typically, the morphologies of the self‐assembled nanostructures from block copolymers are limited to spherical micelles, wormlike micelles and vesicles. Now, a new generation of materials with unique shape and structures, cylindrical soft matter particles (tubisomes), are obtained from the hierarchical self‐assembly of cyclic peptide‐bridged amphiphilic diblock copolymers. The capacity of obtained photo‐responsive tubisomes as potential drug carriers is evaluated. The supramolecular tubisomes pave an alternative way for fabricating polymeric tubular structures, and will expand the toolbox for the rational design of functional hierarchical nanostructures. 相似文献
73.
Dr. Amit Kumar Dr. Nitee Kumari Dr. Sateesh Dubbu Dr. Sumit Kumar Taewan Kwon Dr. Jung Hun Koo Jongwon Lim Inki Kim Prof. Yoon-Kyoung Cho Prof. Junsuk Rho Prof. In Su Lee 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(24):9547-9556
Interest and challenges remain in designing and synthesizing catalysts with nature-like complexity at few-nm scale to harness unprecedented functionalities by using sustainable solar light. We introduce “nanocatalosomes”—a bio-inspired bilayer-vesicular design of nanoreactor with metallic bilayer shell-in-shell structure, having numerous controllable confined cavities within few-nm interlayer space, customizable with different noble metals. The intershell-confined plasmonically coupled hot-nanospaces within the few-nm cavities play a pivotal role in harnessing catalytic effects for various organic transformations, as demonstrated by “acceptorless dehydrogenation”, “Suzuki–Miyaura cross-coupling” and “alkynyl annulation” affording clean conversions and turnover frequencies (TOFs) at least one order of magnitude higher than state-of-the-art Au-nanorod-based plasmonic catalysts. This work paves the way towards next-generation nanoreactors for chemical transformations with solar energy. 相似文献
74.
Jae-Young Rho 《Ultrasonics》1996,34(8):777-783
Ultrasonic techniques have been used to measure the elastic properties of bone. Eight human tibiae were used to determine and map the elastic properties of cortical and cancellous bone. The present study shows cortical bone to be at least orthotropic in its material symmetry. The mechanical properties of cortical bone are more homogeneous along the length than around the circumference. The variations in the properties around the quadrant of cortical bone are small, less than 10%, while differences in the properties around the circumference of cancellous bone are more apparent, approximately 5 times those of cortical bone. The elastic properties of cancellous bone exhibited inhomogeneity and some consistency pattern along both the length and the circumference. 相似文献
75.
Resolving the different silicon clusters in Li12Si7 by 29Si and (6,7)Li solid-state NMR spectroscopy
Köster TK Salager E Morris AJ Key B Seznec V Morcrette M Pickard CJ Grey CP 《Angewandte Chemie (International ed. in English)》2011,50(52):12591-12594
Structural signatures: The analysis of Si-Si and Si-Li connectivities by solid-state NMR spectroscopy allows the different types of silicon clusters to be discriminated in the model lithium silicide compound Li(12)Si(7) (see picture, Si clusters red and blue, Li ions gray). The results provide new NMR spectroscopic strategies with which to differentiate and study the structures formed in silicon-based electrode materials. 相似文献
76.
Two new sesterterpenoids, phorbasones A (1) and B (2), were isolated from the Korean marine sponge Phorbas sp. Their complete structures were elucidated by spectral data and chemical reactions. Phorbasone A exhibited a positive effect on the calcium deposition activity in C3H10T1/2 cells. The biogenic origin of the core structure is believed to be through a novel rearrangement from the ansellone carbon structure. 相似文献
77.
Eun Joo Jung Woo-Jin Lee Myung Jin Kim Sung Hwan Hwang Byung Sup Rho 《Optical and Quantum Electronics》2014,46(10):1373-1378
A hybrid optical waveguide with a \(90^{\circ }\) sharp bend comprising a dielectric straight waveguide, a tapered dielectric strip waveguide, and a microscale metal gap waveguide is proposed, modeled, fabricated, and characterized with the aim of improving the efficiency of light coupling between the dielectric and plasmonic waveguides. The simulation result using the full-vector finite-difference time domain shows a total transmissivity of about 63 % at a wavelength of 1,550 nm. A set of hybrid optical waveguide with a \(90^{\circ }\) bend is fabricated via the two-step photolithography and a metal lift-off process. From the measured result for the characteristics of the fabricated hybrid optical waveguide, the transmission loss was estimated to be about 17 dB, which is in stark contrast with the simulation value. Nevertheless, such a novel coupling scheme may be of potential use in high-density photonic integration applications. 相似文献
78.
We report spatially resolved Raman scattering from Si-doped epitaxial laterally overgrown GaN structures to investigate spatial variations in stress and free electron concentration. The doping-induced increase in the free electron concentration is relatively higher in the laterally overgrown regions than in the coherently grown regions due to the increased contribution of the high-energy A1 longitudinal optical phonon–plasmon coupled mode. In addition, the E2(high) [E2(low)] phonon energy shifts downward (upward) more significantly in the laterally overgrown regions than in the coherently grown regions. The doping-induced Raman shifts of the E2(high) and E2(low) phonons in the laterally overgrown regions are approximately ?0.6 and 0.11 cm?1, respectively, corresponding to the in-plane stress of ~0.22 GPa. 相似文献
79.
80.
The time course of an epidemic can be modeled using the differential equations that describe the spread of disease and by dividing people into “patches” of different sizes with the migration of people between these patches. We used these multi-patch, flux-based models to determine how the time course of infected and susceptible populations depends on the disease parameters, the geometry of the migrations between the patches, and the addition of infected people into a patch. We found that there are significantly longer lived transients and additional “ancillary” epidemics when the reproductive rate R is closer to 1, as would be typical of SARS (Severe Acute Respiratory Syndrome) and bird flu, than when R is closer to 10, as would be typical of measles. In addition we show, both analytical and numerical, how the time delay between the injection of infected people into a patch and the corresponding initial epidemic that it produces depends on R. 相似文献