Novel Crescent-Shaped Cavity Resonator Based on Fano Resonance Spectrum

Plasmonics - World is rich in unconventional oil and various alternatives to petroleum. However, conventional oil production declines so quickly that it is likely these unconventional oil resources...     

Quad-Band Terahertz Absorber Based on Dipolar Resonances of Metamaterial Resonator

Plasmonics - A novel design of a quad-band metamaterial absorber, which consisted of only a metallic resonator on top of a dielectric spacing layer and a metallic board on the bottom, is presented...     

Double Directions Nanoscale Range Finding Using Fano Resonance in Coupled Gratings

In this paper, a theoretical demonstration is given of nanoscale range finding by exciting Fano resonance in coupled gratings. Metallic ridges induce oscillation mode, whose interference with surface plasmon polartions generate narrow Fano resonance. The concept of hybridization is employed to understand the coupling effect of surface plasmon polartions and the oscillation due to metallic ridges. Fano behavior in this structure is captured by using the temporal coupled-mode theory. The gained fundamental understanding opens up new ways to control nanoscale spacing distances and tailor Fano resonance, thus facilitating rational design of nanosensors to improve the performance of nanomotion control systems.

     

Nanoscale Environment Sensing Scheme with Brownian Nanorod and Plasmon Resonator

Tracking a Brownian particle’s motion allows localized parameters at its immediate vicinity to be measured. In this, the introduction of a rod that is drawn by a tunable attractive force to a cylindrical pillar overcomes the problems of the particle drifting away from the venue of measurement as well as colliding with other particles. With nanoscale particles, fluorescence labeling suffers from photobleaching and erratic signal due to blinking, while monitoring the polarization of scattered light is limited by the accuracy of correlating the rotational state of the rod to intensity changes. Here, we advance having the cylindrical pillar operate as a surface plasmon-based optical resonator to sense the contacts of nanorods. Simulations with a one-dimensional summed difference expression developed to reduce the difficulty of analyzing a three-dimensional dataset comprising wavelength, rod orientation, and gap distance allowed us to confirm distinct changes in transmission at 600 nm across all orientation angles with contact to noncontact or vice versa. This allows application of a cutoff transmission threshold. The metric f, which defines the proportion of incidences when the nanorod moves freely under Brownian motion influence, showed reduction with normalized charge increase. Good linear sensitivity responses were found at specific ranges in the f versus normalized charge relationship, which when correlated with temperature T, showed df/dT to be maximal when the normalized charge product value was ?200. From an uncertainty estimation conducted, a restriction to 1 standard deviation variation necessitated only O(10^?2) seconds of sampling using standard photodetectors. This portends significant advantages when sensing environments that are changing temporally rapidly.     

Tunable Fano Resonance Based Mode Interference in Waveguide-Cavity-Graphene Hybrid Structure

In this paper, a graphene strip is introduced into a metal-insulator-metal (MIM)-integrated square cavity hybrid structure; the transmission spectra are theoretically investigated by the finite different time domain (FDTD) methods. An asymmetric Fano resonance dip that has high figure of merit (FOM) value appears in the transmission band. According to the multimode interference coupled mode theory (MICMT) analytical method, the Fano resonance originates from the coherent coupling between TM₁₀ cavity magnetic mode and graphene plasmonic resonance electric mode. The center wavelength, full width at half maximum (FWHM), and FOM value of the Fano resonance can be tuned dynamically by altering the Fermi level of the graphene. Through breaking the symmetry of the hybrid structure or introducing double graphene strips with different Fermi level into hybrid structure, double Fano resonance are realized. This study can provide some theoretical basis and design reference for designing ultrahigh sensitivity plasmonic sensor.

     

Ultra-High Sensitivity Nanosensor Based on Multiple Fano Resonance in the MIM Coupled Plasmonic Resonator

This paper proposes a compact plasmonic structure that is composed of a metal-insulator-metal (MIM) waveguide coupled with a groove and stub resonators, and then investigates it by utilizing the finite element method (FEM). Simulation results show that the interaction between the local discrete state caused by the stub resonator and the continuous spectrum caused by the groove resonator gives rise to one of the two Fano resonances, while the generation of the other resonance relies only on the groove. Meanwhile, the asymmetrical linear shape and the resonant wavelength can be easily tuned by changing the parameters of the structure. By adding stubs on the groove, we excited multiple Fano resonances. The proposed structure can serve as an excellent plasmonic sensor with a sensitivity of 2000 nm/RIU and a figure of merit of about 3.04?×?10³, which can find extensive applications for nanosensors.     

Interference between Cross-correlated Relaxation and the Measurement of Scalar and Dipolar Couplings by Quantitative J

The effects of cross-correlated relaxation in Quantitative J methods are analyzed. One-bond ¹H–¹³C scalar and dipolar couplings of protein methine and methylene sites are obtained by monitoring proton and carbon magnetization in Quantitative J experiments. We find that scalar and dipolar couplings of the same pair of nuclei vary depending on the type of magnetization involved. These discrepancies can be as large as several Hz for methylene moieties. The contribution of dynamic frequency shifts, which are known to affect J couplings, is too small to explain the observed differences. We show that processes of magnetization transfer originated by cross-correlated relaxation are largely responsible for these discrepancies. We estimate the error transferred to methylene J values by cross-correlation interference, and show that is close to the experimentally observed one. Furthermore, this analysis indicates that cross-correlated relaxation effects under isotropic and anisotropic media differ, indicating that errors are not cancelled in residual dipolar coupling measurements.     

Universal Near-Field Interference Patterns of Fano Resonances in Two-Dimensional Plasmonic Crystals

Plasmonics - We have demonstrated directly that the physical origin of Fano resonances in two-dimensional (2D) plasmonic crystals (PCs) is a wave-interference phenomenon. This is achieved by...     

Optical Manipulation of Dielectric Nanoparticles with Au Micro-racetrack Resonator by Constructive Interference of Surface Plasmon Waves

We design a gold micro-racetrack resonator (Au-MRR) which can tightly trap and drive the dielectric nanoparticle to rotate around the circuit of racetrack with an adjustable velocity. Since the surface plasmon waves can be excited and obey the resonance condition of the Au-MRR, the optics force can be strengthened observably due to the resonance. The optical forces applied on dielectric nanoparticle are discussed by utilizing the Maxwell’s stress tensor integration with a numerical finite element method. The depth of longitudinal trapping potential well in the Au-MRR is four times as large as that of a straight waveguide. At the same level of input power, the velocity of particle with radius of 50 nm driven by optical forces on Au-MRR is 200 times larger than that on a straight waveguide. Further, we explore the motion behavior of single nanoparticle lies on different position of Au-MRR, which can provide the details to trap and manipulate multiple nanoparticles and predict their trace of movement. This optimum geometry of Au-MRR allows further enhancement of the optical forces which is expected to realize all-optical on-chip manipulation of nanoparticles, biomolecules, and many other nanomanipulation applications.     

Analysis of the Precision,Robustness, and Speed of Elastic Resonator Interference Stress Microscopy

Localization-microscopy-based methods are widely used to map the forces that cells apply to their substrates and to study important questions of cellular biomechanics. By contrast, elastic resonator interference stress microscopy (ERISM) uses an interference-based approach, which requires low light intensity and facilitates imaging of cellular forces with extreme precision (down to pN forces) and robustness (e.g., for continuous force monitoring over weeks). Here, the measurement trade-offs and numerical considerations required to optimize the performance of ERISM are described. The crucial parts of the fitting algorithm and the computational tools used to evaluate the data are explained in detail, and the precision and accuracy achievable with ERISM are analyzed. Additional features that can improve the robustness of ERISM further are discussed. The implementation of the analysis algorithm is verified with simulated test data and with experimental data. In addition, an approach to increase the acquisition speed of ERISM by a factor of four compared to the original implementation is described. In combination, these strategies allow us to measure the forces generated by a neural growth cone with high temporal resolution and continuously over several hours.     

Magnetic-Based Fano Resonance by a Trimer with Y-shaped Gap

We introduce a Y-shaped gap into a silver disk to break the structure symmetry which can be looked as a loop-linked structure. Magnetic resonances are excited by incident light when incident electric field is parallel to the trimer plane. Fano resonance is generated by the coupling between bright electric mode and dark magnetic mode. These resonances can be adjusted by tuning the gap size, the radius of trimer, and the position of Y-shaped gap. The extinction cross section of the structure is calculated with the finite element method (FEM). The maximum figure of merit (FOM) is 37.8. Both the magnetic and electric field are greatly enhanced at the Fano dip and the magnetic resonance peak.     

A Thorough Dynamic Interpretation of Residual Dipolar Couplings in Ubiquitin

The presence of slow motions with large amplitudes, as detected by measurements based on residual dipolar couplings [Peti, W., Meiler, J., Brueschweiler, R. and Griesinger, C. (2002) J. Am. Chem. Soc., 124, 5822–5833], has stirred up much discussion in recent years. Based on ubiquitin NH residual dipolar couplings (rdcs) measured in 31 different alignment conditions, a model-free analysis of structure and dynamics [Meiler, J., Peti, W., Prompers, J., Griesinger, C. and Brueschweiler, R. (2001) J. Am. Chem. Soc., 123, 6098–6107] is presented. Starting from this broad experimental basis, rdc-based order parameters with so far unattained accuracy were determined. These rdc-based order parameters underpin the presence of new modes of motion slower than the inverse overall tumbling correlation time. Amplitudes and anisotropies of the motion were derived. The effect of structural noise on the results was proven to be negligible. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Interference of hepatitis A virus replication by small interfering RNAs

The rate of acute liver failure due to hepatitis A virus (HAV) has not decreased, and therapy of severe infections is still of major interest. Using a DNA-based HAV replicon cell culture system, we demonstrate that small interfering RNAs (siRNAs) targeted against viral sequences or a reporter gene contained in the viral genome specifically inhibit HAV RNA replication in HuhT7 cells. Combinations of siRNAs were more effective suppressors of HAV RNA replication. Also, siRNAs targeted against HAV 2C and 3D inhibited the expression of the respective protein. Expressions of endogenous beta-actin and double-stranded-specific RNA-activated serin/threonine kinase (PKR) were unaltered, demonstrating that the siRNA inhibitory effect was not connected to interferon inhibition, but rather was specifically targeted against HAV RNA. These results suggest that RNA interference might ultimately be useful in treatment of severe HAV infection with or without chronic liver diseases.     

A Novel Plasmonic Nanolaser Based on Fano Resonances with Super Low Threshold

Plasmonics - A novel plasmonic nanolaser is proposed based on a heptamer of silver nanoparticles surrounded by gain material. Optical properties of the proposed laser are analyzed using the finite...     

dsRNA 介导的RNA干扰

在多种生物中 ,外源或内源性的双链ＲＮＡ(ｄｏｕｂｌｅ ｓｔｒａｎｄｅｄＲＮＡ ,ｄｓＲＮＡ)导入细胞中 ,与ｄｓＲＮＡ同源的ｍＲＮＡ则受到降解 ,因而其相应的基因受到抑制。这种转录后基因沉默 (ｐｏｓｔ ｔｒａｎｓｃｒｉｐｔｉｏｎａｌｇｅｎｅｓｉｌｅｎｃｉｎｇ ,ＰＴＧＳ)机制首先在线虫 (Ｃ .ｅｌｅｇａｎｓ)中得以证实。由于这是一种在ＲＮＡ水平的基因表达抑制 ,故也称为ＲＮＡ干扰 (ＲＮＡｉｎｔｅｒｆｅｒ ｅｎｃｅ) ,简称ＲＮＡｉ[1] 。随后发现 ,在各种生物 ,如果蝇[2 ] 、拟南芥菜[3 ] 、及小鼠[4] 等均存在ｄｓＲＮＡ介导…     

Transportation of Nanoscale Cargoes by Myosin Propelled Actin Filaments

Myosin II propelled actin filaments move ten times faster than kinesin driven microtubules and are thus attractive candidates as cargo-transporting shuttles in motor driven lab-on-a-chip devices. In addition, actomyosin-based transportation of nanoparticles is useful in various fundamental studies. However, it is poorly understood how actomyosin function is affected by different number of nanoscale cargoes, by cargo size, and by the mode of cargo-attachment to the actin filament. This is studied here using biotin/fluorophores, streptavidin, streptavidin-coated quantum dots, and liposomes as model cargoes attached to monomers along the actin filaments (“side-attached”) or to the trailing filament end via the plus end capping protein CapZ. Long-distance transportation (>100 µm) could be seen for all cargoes independently of attachment mode but the fraction of motile filaments decreased with increasing number of side-attached cargoes, a reduction that occurred within a range of 10–50 streptavidin molecules, 1–10 quantum dots or with just 1 liposome. However, as observed by monitoring these motile filaments with the attached cargo, the velocity was little affected. This also applied for end-attached cargoes where the attachment was mediated by CapZ. The results with side-attached cargoes argue against certain models for chemomechanical energy transduction in actomyosin and give important insights of relevance for effective exploitation of actomyosin-based cargo-transportation in molecular diagnostics and other nanotechnological applications. The attachment of quantum dots via CapZ, without appreciable modulation of actomyosin function, is useful in fundamental studies as exemplified here by tracking with nanometer accuracy.     

Interference Among Group A Arboviruses

Interference among group A arboviruses is described which does not involve the mediation of interferon. Interference was observed only if the interfering virus had an advantage over the challenge virus, either in time or in multiplicity of infection. Adsorption, penetration, and uncoating of challenge virus did not appear to be inhibited, but the synthesis of infectious viral ribonucleic acid of the challenge virus was significantly retarded. It was shown with temperature-sensitive viruses or mutants that the replication of viral ribonucleic acid by the interfering virus was required to establish interference. A mechanism of interference based on a competition for replication sites or substrates is compared with other possible explanations.     

A MIM Filter Based on a Side-Coupled Crossbeam Square-Ring Resonator

In this paper, a surface plasmon polarition filter based on a side-coupled crossbeam square-ring resonator is presented and the transmission characteristics of the filter are analyzed by using the finite difference time domain method. The simulation results indicate that the proposed resonator supports multiple resonant modes, and these resonant modes can be adjusted all together by varying the length and refractive index of the outer square ring or partially adjusted by changing the width and refractive index of the crossbeam. By adding two coupled waveguides to the structure, we further demonstrate that a multiple wavelength download filter can be achieved via different coupled waveguides. The proposed structure has potential applications in plasmonic integrated circuits.