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101.
Choi M Lee SH Kim Y Kang SB Shin J Kwak MH Kang KY Lee YH Park N Min B 《Nature》2011,470(7334):369-373
Controlling the electromagnetic properties of materials, going beyond the limit that is attainable with naturally existing substances, has become a reality with the advent of metamaterials. The range of various structured artificial 'atoms' has promised a vast variety of otherwise unexpected physical phenomena, among which the experimental realization of a negative refractive index has been one of the main foci thus far. Expanding the refractive index into a high positive regime will complete the spectrum of achievable refractive index and provide more design flexibility for transformation optics. Naturally existing transparent materials possess small positive indices of refraction, except for a few semiconductors and insulators, such as lead sulphide or strontium titanate, that exhibit a rather high peak refractive index at mid- and far-infrared frequencies. Previous approaches using metamaterials were not successful in realizing broadband high refractive indices. A broadband high-refractive-index metamaterial structure was theoretically investigated only recently, but the proposed structure does not lend itself to easy implementation. Here we demonstrate that a broadband, extremely high index of refraction can be realized from large-area, free-standing, flexible terahertz metamaterials composed of strongly coupled unit cells. By drastically increasing the effective permittivity through strong capacitive coupling and decreasing the diamagnetic response with a thin metallic structure in the unit cell, a peak refractive index of 38.6 along with a low-frequency quasi-static value of over 20 were experimentally realized for a single-layer terahertz metamaterial, while maintaining low losses. As a natural extension of these single-layer metamaterials, we fabricated quasi-three-dimensional high-refractive-index metamaterials, and obtained a maximum bulk refractive index of 33.2 along with a value of around 8 at the quasi-static limit. 相似文献
102.
B. C. Yoo S-H. Hong J-L. Ku Y-H. Kim Y-K. Shin S-G. Jang I-J. Kim S-Y. Jeong J-G. Park 《Cellular and molecular life sciences : CMLS》2009,66(2):350-364
Comparative analysis of proteomes using 5-fluorouracil (5-FU)-resistant human colon cancer cell line revealed that decreased
galectin-3 expression was significantly associated with retarded proliferation. However, in the presence of 5-FU proliferation
rate of cells with suppressed galectin-3 expression did not differ from that of cells with normal galectin-3 expression, even
galectin-3 suppression augmented apoptosis. Mechanism by which galectin-3 regulates cancer cell proliferation has been identified
in immunoprecipitates of the anti-galectin-3 antibody. Heterogeneous nuclear ribonucleoprotein Q (hnRNP Q) was identified
as a protein interacting with galectin-3. Interestingly, while galectin-3 protein was not affected by the hnRNP Q level, its
suppression was accompanied by a decrease in hnRNP Q expression. The present study demonstrates that galectin-3 stabilizes
hnRNP Q via complex formation, and reduction in the hnRNP Q level leads to slow proliferation and less susceptibility to 5-FU.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
B.C.Yoo; S-H.Hong; These two authors contributed equally to this work.
Received 10 September 2008; received after revision 19 October 2008; accepted 07 November 2008 相似文献
103.
Watson DM Bohac CJ Hull C Forrest WJ Furlan E Najita J Calvet N d'Alessio P Hartmann L Sargent B Green JD Kim KH Houck JR 《Nature》2007,448(7157):1026-1028
Class 0 protostars, the youngest type of young stellar objects, show many signs of rapid development from their initial, spheroidal configurations, and therefore are studied intensively for details of the formation of protoplanetary disks within protostellar envelopes. At millimetre wavelengths, kinematic signatures of collapse have been observed in several such protostars, through observations of molecular lines that probe their outer envelopes. It has been suggested that one or more components of the proto-multiple system NGC 1333-IRAS 4 (refs 1, 2) may display signs of an embedded region that is warmer and denser than the bulk of the envelope. Here we report observations that reveal details of the core on Solar System dimensions. We detect in NGC 1333-IRAS 4B a rich emission spectrum of H2O, at wavelengths 20-37 microm, which indicates an origin in extremely dense, warm gas. We can model the emission as infall from a protostellar envelope onto the surface of a deeply embedded, dense disk, and therefore see the development of a protoplanetary disk. This is the only example of mid-infrared water emission from a sample of 30 class 0 objects, perhaps arising from a favourable orientation; alternatively, this may be an early and short-lived stage in the evolution of a protoplanetary disk. 相似文献
104.
105.
106.
Choline acetyltransferase and acetylcholinesterase in spinal motor neurons cultured in vitro 总被引:1,自引:0,他引:1
S U Kim 《Experientia》1972,28(5):537-538
107.
An active queue management (AQM) algorithm called MCHOKeM is presented, which is borrowed from CHOKeW that draws multi-packets at random from the buffer, the multi-packets are compared with an arriving packet and abandoned if they are from the same flow. But MCHOKeM uses multiple virtual queues for different priority packets and enhances the drawing function by adjusting the maximum number of draws based on the current status of virtual queue length. The number of parameters that MCHOKeM needs to maintain is determined by the number of priority levels being supported by the router, which usually has a small limited value. In order to explain the features of MCHOKeM, an analytical model is used. A series of simulation tests to evaluate the performance are given. 相似文献
108.
K. Oomagari H. Uchimura T. Matsumoto H. Yokoo M. Hirano J. S. Kim T. Nakahara 《Cellular and molecular life sciences : CMLS》1984,40(11):1288-1290
Summary Serotonin and 5-hydroxyindoleacetic acid (5-HIAA) were measured in individual nuclei of rat hypothalamus and other brain areas using HPLC with electrochemical detection. 5-HIAA levels were first demonstrated in hypothalamic and some discrete brain areas. The 5-HIAA/5-HT ratio was highest in the n. caudatus putamen, high in the n. ventromedialis and lowest in the n. suprachiasmaticus. 相似文献
109.
Adenyl cyclase stimulation by aspirin in rat gastric mucosa 总被引:1,自引:0,他引:1
110.
Following thyroidectomy, monoamine oxidase (MAO) activities toward tyramine decreased significantly by 20% in the nucleus periventricularis and the nucleus arcuatus among the 3 hypothalamic nuclei of the rat, while MAO activity toward serotonin decreased significantly by 10% only in the nucleus periventricularis. It is suggested that thyroidectomy induced selective changes on the multiple forms of MAO in the discrete circumventricular nuclei. 相似文献