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...     

Near-Field Optical Analysis of Plasmonic Nano-Probes for Top-Illumination Tip-Enhanced Raman Scattering

Top-illumination tip-enhanced Raman scattering (TI-TERS) has recently emerged as a promising near-field vibrational spectroscopy method that can be adapted on an upright optical microscope. With a relatively simplified optics, TI-TERS can probe both opaque and transparent samples making them a promising tool in nanoscale chemical analysis. One of the critical components of TI-TERS is the plasmonic nano-tip used to enhance the Raman spectroscopic signature. Herein, we numerically studied the near-field optical properties of conventional gold tip (20 nm radius of curvature) and two varieties of optical antenna-based tips in the context of TI-TERS. Optical antenna-based tips included a 40-nm gold nanoparticle attached to a dielectric tip and a 50-nm equilateral gold nanotriangle attached to a dielectric tip. We evaluated the Raman enhancement spectra as a function of experimental variables such as underlying substrate and angle of the tip with respect to substrate normal. Our analysis revealed that conventional gold tip facilitates superior enhancement and optical antenna-based tips facilitate superior spectral bandwidth and lateral resolution in TI-TERS configuration. Tips with higher enhancement can be harnessed for ultra-sensitive measurements, and tips with broader spectral bandwidth can be utilized to enhance both Stokes and anti-Stokes component of the Raman spectra.     

Plasmonic Near-Field Effect on Visible and Near-Infrared Emissions from Self-Assembled Gold Nanoparticle Films

Plasmonics - In this work, we have performed a systematic investigation of the plasmon near-field effect on photoluminescence (PL) behavior of the annealed self-assembled gold nanostructured films....     

Quantifying and Comparing the Near-Field Enhancement,Photothermal Conversion,and Local Heating Performance of Plasmonic SiO2@Au Core-Shell Nanoparticles

Plasmonics - In this work, the finite element method and two-temperature model were used to optimize the near electric field, photothermal conversion efficiency, and local heating of SiO2@Au...     

Morphology and Development of Mirror-Image Doublets of Stylonychia mytilus

This paper describes the cortical anatomy and development of mirror-image doublets of Stylonychia mytilus, analyzed using the protargol technique. The reversed, or “left-handed” (LH) component of these doublets is a mirror image of the normal or “right handed” (RH) component with regard to the arrangement of cortical structures. The mirror-image patterning is imperfect, however, as the individual ciliary structures of the LH component all are of normal internal asymmetry, and the orientation of membranelles is inverted. Certain structures that would be expected to form near the line of symmetry are absent. During cell division and cortical reorganization, ciliary primordia arise and become arranged in a mirror-image pattern that is more perfect than that exhibited by the mature structures. Deviations from a mirror-image pattern appear at late stages when organelle sets differentiate within ciliary primordia: for example, the membranelle set differentiates within the oral primordium of the LH component in a sequence that is an inversion rather than a mirror image of the corresponding sequence of the RH component. This mixed control of oral development by different cortical “informational systems” accounts for some of the characteristic abnormalities of the mature oral structures of the LH component.     

Nonlocal Plasmonic Modes and Plasmonic Band Structures in Cylindrically Curved Graphene

Plasmonics - In this paper, hydrodynamic model has been analytically solved to investigate the nonlocal plasmons in cylindrically curved graphene layers. Within the quasi-static approximation, the...     

Tunable Ultrahigh Order Surface Plasmonic Resonance in Multi-Ring Plasmonic Nanocavities

Optical properties of multi-ring with spatial symmetry breaking are investigated theoretically. Tunable ultrahigh order surface plasmonic resonance is achieved, which is found to be sensitive to geometric parameters. Certain high-order surface plasmonic resonances can be either suppressed or enhanced when geometrical parameters are adjusted. Moreover, more than one quadrupolar-dipolar, octupolar-dipolar, and hexadecapolar-dipolar mode of the surface plasmonic resonance can be achieved. The asymmetry also allows the generation of strong electric field enhancement with these nanostructures that can be applied in the field of surface-enhanced spectroscopy and biosensing.     

Pattern Formation in Mirror-Image Doublets of the Ciliate Stylonychia pustulata

ABSTRACT. Mirror-image symmetry doublets of the ciliate Stylonychia pustulata were obtained from the progenies of dividing cells in which cell division was inhibited by heat-shocks. In two components consisting of the doublet, the left (cell's) component possessed ciliary organelles arranged in almost the same pattern as in normal singlets, while the right one had surface organelles located in a mirror-image symmetry of those of the left component. In cell division of the doublet, two sets of ciliary primordia that were arranged in a mirror-image symmetry developed synchronously in both components. In about 80% of oral primordia (OP) of the right components, the arrangement of the membranellar bands became abnormal. In some cases, OP of the right component were occasionally separated into two longitudinal halves, each consisting of normal membranelles and inverted membranelles. A set of primordia of the paroral membranelles and fronto-ventro-transverse cirri was rarely derived from the basal bodies of the right half with a band of normal membranelles. As a result, a third component with the ciliary organelles normally arranged emerged on the right side of the original right component. The differentiation of membranelles and segmentation of the primordial streaks into cim proceeded from anterior to posterior. A cytoplasmic bulge with multiple right marginal cirral rows was frequently formed at the right margin of the doublet. The behavior in the separation of third and fourth streaks from a primordial streak of dorsal cirri was not mirror-image symmetrical in each component.     

Localizing triplet periodicity in DNA and cDNA sequences

Background  

The protein-coding regions (coding exons) of a DNA sequence exhibit a triplet periodicity (TP) due to fact that coding exons contain a series of three nucleotide codons that encode specific amino acid residues. Such periodicity is usually not observed in introns and intergenic regions. If a DNA sequence is divided into small segments and a Fourier Transform is applied on each segment, a strong peak at frequency 1/3 is typically observed in the Fourier spectrum of coding segments, but not in non-coding regions. This property has been used in identifying the locations of protein-coding genes in unannotated sequence. The method is fast and requires no training. However, the need to compute the Fourier Transform across a segment (window) of arbitrary size affects the accuracy with which one can localize TP boundaries. Here, we report a technique that provides higher-resolution identification of these boundaries, and use the technique to explore the biological correlates of TP regions in the genome of the model organism C. elegans.     

Plasmonic Focusing in Nanostructures

In this review, we show that by designing the metallic nanostructures, the surface plasmon (SP) focusing has been achieved, with the focusing spot at a subwavelength scale. The central idea is based on the principle of optical interference that the constructive superposition of SPs with phase matching can result in a considerable electric-field enhancement of SPs in the near field, exhibiting a pronounced focusing spot. We first reviewed several new designs for surface plasmon focusing by controlling the metallic geometry or incident light polarization: We made an in-plane plasmonic Fresnel zone plates, a counterpart in optics, which produces an obvious SP focusing effect; We also fabricated the symmetry broken nanocorrals which can provide the spatial phase difference for SPs, and then we propose another plasmon focusing approach by using semicircular nanoslits, which gives rise to the phase difference through changing refractive index of the medium in the nanoslits. Further, we showed that the spiral metallic nanostructure can be severed as plasmonic lens to control the plasmon focusing under a linearly polarized light with different angles.

     

Ascertaining Plasmonic Hot Electrons Generation from Plasmon Decay in Hybrid Plasmonic Modes

Plasmonics - In the propagating process along metal surface, surface plasmon polaritons (SPPs) mainly decay into thermal loss or release into photons, while a part of them were converted into...     

Improvements in the Synthesis of L-Ribonucleosides for the Preparation of Mirror-Image Oligoribonucleotides

Abstract

Different improvements are described for the chemical synthesis of L-ribonucleosides corresponding to the four natural bases. These nucleosides properly protected were used to synthesize successfully a 27-base long L-oligoribonucleotide.     

Morphology and Development of Left-Handed Singlets Derived from Mirror-Image Doublets of Stylonychia mytilus

Mirror-image doublets of Stylonychia mytilus include 2 sets of cortical structures, one with the normal “right-handed” (RH) arrangement, the other with a reversed “left-handed” (LH) arrangement. These sets, however, are incomplete, with certain structures, most notably cirri of the right marginal type, missing near the line of symmetry. When a mirror-image doublet is bisected longitudinally to separate the RH and LH components physically, each fragment undergoes a regeneration process that restores a complete set of cortical structures, including the previously missing cirri of the right marginal type. In the resulting LH cell, all ciliary structures are present in an arrangement that is globally reversed in relation to that found in RH cells; in particular, marginal cirri of the left-marginal type are formed at the cell's right margin, and marginal cirri of the right-marginal type are produced at the cell's left margin. Whereas the regenerated RH fragment always divides and initiates a clone of normal singlets, the LH fragment, though structurally nearly complete, in all cases eventually dies without dividing. The cause of death is starvation due to the formation of an abnormal oral apparatus. In the Discussion, we consider the nature and consequences of a reversal of global positional information.     

Localizing a-Amylase Gene Expression in Germinated Rice Grains

In situ hybridization was used to localize the sites of expressionfor two a-amylase genes (RAmy1A and RAmy3D) in rice (Oryza sativaL.) over five days of germination. Messenger RNAs from bothgenes were initially detected in the scutellar epithelium andappeared at later stages of germination in the aleurone layer.RAmy3D mRNA reached its peak of accumulation 2 days(d) earlierin the scutellar epithelium than RAmy1A mRNA. Both mRNAs continuedto accumulate in the aleurone layer up to 5 d of germination,although RAmy1A mRNA reached significantly higher levels thanRAmy3D mRNA. Overall, the aleurone layer was responsible forproducing the majority of the total grain a-amylase mRNA. (Received July 27, 1991; Accepted November 6, 1991)     

Electromagnetic-Induced Transparency and Slow Light in Plasmonic Metasurfaces

Plasmonics - We report numerically electromagnetic-induced transparency (EIT) and Fano resonances in simple plasmonic metasurfaces consisting of gold nanobars arranged in pi, H, and four-shaped...     

Complex Polarization Response in Plasmonic Nanospirals

Archimedean nanospirals exhibit many far-field resonances that result from the lack of symmetry and strong intra-spiral plasmonic interactions. Here, we present a computational study, with corroborating experimental results, on the plasmonic response of the 4π Archimedean spiral as a function of incident polarization, for spirals in which the largest linear dimension is less than 550 nm. We discuss the modulation of the near-field structure for linearly and circularly polarized light in typical nanospiral configurations. Computational studies of the near-field distributions excited by circularly polarized light illustrate the effects of chirality on plasmonic mechanisms, while rotation of linearly polarized light provides a detailed view of the effects of broken symmetry on nanospiral fields in any given direction in the plane of the spiral. The rotational geometry exhibits a preference for circular polarization that increases near-field enhancement compared to excitation with linearly polarized light and exchanges near-field configurations and resonant modes. By analyzing the effects of polarization and wavelength on the near-field configurations, we also show how the nanospiral could be deployed in applications such as tunable near-field enhancement of nonlinear optical signals from chiral molecules.     

Boosting and suppressing mitotic phosphorylation

Reversible protein phosphorylation is an essential aspect of mitosis and forms the basis of nuclear envelope breakdown, chromosome condensation and spindle assembly. Through global phosphoproteomic analysis, it has become clear that overall protein phosphorylation and phosphosite occupancy is most abundant during mitosis. At mitotic exit, this abundant phosphorylation must be reversed, and this process requires massive and rapid protein dephosphorylation. In addition to this global shift in protein phosphorylation, careful spatial control of protein (de)phosphorylation is equally important for spindle assembly, chromosome disjunction and chromosome alignment. In this review, we discuss the underlying mechanisms that enforce the dramatic global shift in protein phosphorylation as well as the mechanisms that allow for highly localized substrate phosphorylation in mitosis.     

Surface-Assisted Carrier Excitation in Plasmonic Nanostructures

We present a quantum-mechanical model for surface-assisted carrier excitation by optical fields in plasmonic nanostructures of arbitrary shape. We derive an explicit expression, in terms of local fields inside the metal structure, for surface absorbed power and surface scattering rate that determine the enhancement of carrier excitation efficiency near the metal-dielectric interface. We show that surface scattering is highly sensitive to the local field polarization and can be incorporated into metal-dielectric function along with phonon and impurity scattering. We also show that the obtained surface scattering rate describes surface-assisted plasmon decay (Landau damping) in nanostructures larger than the nonlocality scale. Our model can be used for calculations of plasmon-assisted hot carrier generation rates in photovoltaics and photochemistry applications.