scholarly journals Role of bianisotropy in negative permeability and left-handed metamaterials

2002 ◽  
Vol 65 (14) ◽  
Author(s):  
Ricardo Marqués ◽  
Francisco Medina ◽  
Rachid Rafii-El-Idrissi
Keyword(s):  
Negative Permeability ◽  
Left Handed

scholarly journals Role of Histone N-Terminal Tails and Their Acetylation in Nucleosome Dynamics

2000 ◽  
Vol 20 (19) ◽  
pp. 7230-7237 ◽  
Author(s):  
Violette Morales ◽  
Hélène Richard-Foy
Keyword(s):  
Topoisomerase I ◽  
Globular Domain ◽  
Histone Tail ◽  
Histone Tails ◽  
Nucleosome Dynamics ◽  
Nucleosome Structure ◽  
Left Handed ◽  
Negative Supercoiling ◽  
And Function

ABSTRACT Histone N-terminal tails are central to the processes that modulate nucleosome structure and function. We have studied the contribution of core histone tails to the structure of a single nucleosome and to a histone (H3-H4)2 tetrameric particle assembled on a topologically constrained DNA minicircle. The effect of histone tail cleavage and histone tail acetylation on the structure of the nucleoprotein particle was investigated by analyzing the DNA topoisomer equilibrium after relaxation of DNA torsional stress by topoisomerase I. Removal of the H3 and H4 N-terminal tails, as well as their acetylation, provoked a dramatic change in the linking-number difference of the (H3-H4)2 tetrameric particle, with a release of up to 70% of the negative supercoiling previously constrained by this structure. The (H3-H4)2 tetramers containing tailless or hyperacetylated histones showed a striking preference for relaxed DNA over negatively supercoiled DNA. This argues in favor of a change in tetramer structure that constrains less DNA and adopts a relaxed flat conformation instead of its left-handed conformation within the nucleosome. In contrast neither removal or hyperacetylation of H3 and H4 tails nor removal or hyperacetylation of H2A and H2B N-terminal tails affected the nucleosome structure. This indicates that the globular domain of H2A and H2B is sufficient to stabilize the tailless or the hyperacetylated (H3-H4)2tetramer in a left-handed superhelix conformation. These results suggest that the effect of histone tail acetylation that facilitates transcription may be mediated via transient formation of an (H3-H4)2 tetrameric particle that could adopt an open structure only when H3 and/or H4 tails are hyperacetylated.

scholarly journals A Novel Tunable Triple-Band Left-Handed Metamaterial

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Si Li ◽  
Atef Z. Elsherbeni ◽  
Wenhua Yu ◽  
Wenxing Li ◽  
Yunlong Mao
Keyword(s):  
Current Density ◽  
Surface Current ◽  
Wide Band ◽  
The Other ◽  
Negative Permittivity ◽  
Negative Permeability ◽  
Surface Current Density ◽  
Density Distributions ◽  
Left Handed ◽  
Triple Band

A novel tunable triple-band left-handed metamaterial (LHM) composed of a single-loop resonator (SLR) and a variable capacitor-loaded short wire pair (CL-SWP) printed on both sides of a substrate is presented in this paper. The CL-SWP-based metamaterial (MTM) is a novel single-sided LHM. It is theoretically analyzed capable of extracting tunable negative permeability and a wide-band negative permittivity. We ran simulations for the CL-SWP-based MTM, the SLR-based MTM, and the proposed LHM. Together with the measured results, it is identified that this novel LHM exhibits a tunable triple-band left-handed (LH) property. With the increase of the loaded capacitance, one LH band is relatively stable, while the other two are moving towards lower frequencies with their bandwidth getting wider and narrower, respectively. The surface current density distributions indicate that the first LH band is mainly decided by the SLR, one of the rest 2 LH bands is mainly decided by the CL-SWP, and the other one is decided by the SLR and CL-SWP together.

POSSIBLE EXISTENCE OF GRANULAR LEFT-HANDED MATERIALS BASED ON BRUGGEMAN FORMALISM

2010 ◽  
Vol 24 (27) ◽  
pp. 5469-5474
Author(s):  
WEIKAI XU ◽  
YANZHANG DONG ◽  
SHUTIAN LIU
Keyword(s):  
Negative Permittivity ◽  
Negative Permeability ◽  
Left Handed ◽  
Two Component ◽  
Current Stage

In the current stage, left-handed material (LHM) has aroused wide interest based on several basic prototypes such as metamaterials. In this work, we have theoretically investigated the possible existence of granular LHM by using the Bruggeman formalism. The Wiener bounds and the Hashin–Shtrikman bounds were invoked and some examples were represented. We had found that when the dissipations are increased adequately, the estimates of the Bruggeman formalism will lie within the two bounds rigorously, even if the two permittivities have real parts of opposite signs. Thus, one particulate LHM may be achieved by choosing the two component mediums with negative permittivity and negative permeability, respectively.

Double Negative Optical Metamaterial with All-Dielectric Fishnet Structure

2013 ◽  
Vol 873 ◽  
pp. 813-818 ◽  
Author(s):  
Chu Wen Lan ◽  
Xiao Jian Fu ◽  
Xiao Ming Liu ◽  
Bo Li ◽  
Ji Zhou
Keyword(s):  
High Performance ◽  
Figure Of Merit ◽  
Negative Refraction ◽  
Wide Band ◽  
Negative Permeability ◽  
Double Negative ◽  
Negative Index ◽  
Left Handed ◽  
Silicon Based ◽  
Multilayer Dielectric

An all-dielectric fishnet metamaterial (DFM) composed of multilayer dielectric structure with periodically patterned holes is proposed to generate left-handed behavior in optical frequency region. Different from the metallic fishnet negative index metamaterial realized by coupling the neighbouring functional layers along the propagation direction, this DFM owes its simultaneous negative permeability and permittivity to the hybrid coupled resonances in the same layer. Based on this configration, a wide-band and polarization-independent negative refraction with maximum figure of merit as large as 13.85 is obtained by a silicon-based DFM at 450 nm wavelength. Simple and easy to fabricate, this concept is believed to provide an alternative route to realize high-performance negative index metamateirals at optical frequencies.

scholarly journals The role of dispersion in the propagation of rotating beams in left-handed materials

2009 ◽  
Vol 17 (7) ◽  
pp. 5645 ◽  
Author(s):  
Qiang Lv ◽  
Hongyao Liu ◽  
Hailu Luo ◽  
Shuangchun Wen ◽  
Weixing Shu ◽  
...  
Keyword(s):  
Rotating Beams ◽  
Left Handed
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