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Chansik Yang, Sugyeong Kwon, Se-Jong Kim, Minseon Jeong, Ji-Young Park, Dongeun Park, Soon Jun Hong, Jong-Wha Jung, Chungho Kim
Cardiovascular disease, which is caused by unregulated platelet aggregation, is one of the main causes of deaths worldwide. Many studies have focused on natural products with antiplatelet effects as a safe alternative therapy in order to prevent the disease. In this context, an in-house chemical library was screened to find natural products capable of inhibiting the interaction between platelet integrin αIIbβ3 and fibrinogen, which is an essential step in platelet aggregation. On the basis of the screening results, indothiazinone, an alkaloid found in microbial cultures, was identified as a potential antiplatelet agent...
April 22, 2017: Chemical Biology & Drug Design
Stefano Stassi, Alessandro Chiadò, Giuseppe Calafiore, Gianluca Palmara, Stefano Cabrini, Carlo Ricciardi
Fano resonance refers to an interference between localized and continuum states that was firstly reported for atomic physics and solid-state quantum devices. In recent years, Fano interference gained more and more attention for its importance in metamaterials, nanoscale photonic devices, plasmonic nanoclusters and surface-enhanced Raman scattering (SERS). Despite such interest in nano-optics, no experimental evidence of Fano interference was reported up to now for purely nanomechanical resonators, even if classical mechanical analogies were referred from a theoretical point of view...
April 21, 2017: Scientific Reports
Wuyun Shang, Fajun Xiao, Weiren Zhu, Hongsen He, Malin Premaratne, Ting Mei, Jianlin Zhao
Being an enabling technology for applications such as ultrasensitive biosensing and surface enhanced spectroscopy, enormous research interests have been focused on further boosting the local field enhancement at Fano resonance. Here, we demonstrate a plasmonic Fano resonance resulting from the interference between a narrow magnetic dipole mode and a broad electric dipole mode in a split-ring resonator (SRR) coupled to a nanoarc structure. Strikingly, when subjected to an azimuthally polarized beam (APB) excitation, the intensity enhancement becomes more than 60 times larger than that for a linearly polarized beam (LPB)...
April 21, 2017: Scientific Reports
Haitong Yu, Dong Liu, Zhen Yang, Yuanyuan Duan
We show theoretically that 2D rectangular gratings on the surface of GaSb can serve as an "anti-reflection" pattern for nano-gap thermophotovoltaic (TPV) devices, which significantly enhances near-field radiative flux from the emitter to a GaSb cell, thus improving output power and conversion efficiency. The system in this study is a 200-nm gap TPV power generation system with a planar infrared plasmonic emitter and GaSb cell. Rigorous coupled-wave analysis is used to calculate the spectral near-field radiative flux involving periodic structures...
April 21, 2017: Scientific Reports
Šarūnas Meškinis, Domantas Peckus, Andrius Vasiliauskas, Arvydas Čiegis, Rimantas Gudaitis, Tomas Tamulevičius, Iryna Yaremchuk, Sigitas Tamulevičius
Ultrafast relaxation dynamics of diamond-like carbon (DLC) films with embedded Ag nanoparticles (DLC:Ag) and photovoltaic properties of heterojunctions consisting of DLC:Ag and crystalline silicon (DLC:Ag/Si) were investigated by means of transient absorption (TAS) spectroscopy and photovoltaic measurements. The heterojunctions using both p type and n type silicon were studied. It was found that TAS spectra of DLC:Ag films were dependent on the used excitation wavelength. At wavelengths where Ag nanoparticles absorbed light most intensively, only DLC signal was registered...
December 2017: Nanoscale Research Letters
Haidong Zhang, Hanyu Liu, Kaya Wei, Oleksandr O Kurakevych, Yann Le Godec, Zhenxian Liu, Joshua Martin, Michael Guerrette, George S Nolas, Timothy A Strobel
Large-volume, phase-pure synthesis of BC8 silicon (Ia3[over ¯], cI16) has enabled bulk measurements of optical, electronic, and thermal properties. Unlike previous reports that conclude BC8-Si is semimetallic, we demonstrate that this phase is a direct band gap semiconductor with a very small energy gap and moderate carrier concentration and mobility at room temperature, based on far- and midinfrared optical spectroscopy, temperature-dependent electrical conductivity, Seebeck and heat capacity measurements...
April 7, 2017: Physical Review Letters
Xiaolin Kang, Qifeng Ruan, Han Zhang, Feng Bao, Jun Guo, Minghua Tang, Si Cheng, Jianfang Wang
Concave nanocrystals usually exhibit a large electromagnetic-field enhancement and superior catalytic performance due to their sharp corners, negative curvature and high-index facets. Conventional gold bipyramids (AuBPs) possess intriguing plasmonic properties which are attractive for various applications while the surface curvature of the reported bipyramids has not been fine-tuned to concave or convex structures to date. Additionally, the longitudinal surface plasmon resonance (LSPR) wavelengths of conventional AuBPs are mostly located in the range of 650-1350 nm and the sizes of these nanoparticles are usually not beyond 350 nm, which are not facilitated to some nano-focusing and nanophotonic applications...
April 21, 2017: Nanoscale
Naema Othman, Pierre Berini
We propose and investigate a Schottky contact detector where the contact metal is a nanoscale metal stripe waveguide supporting surface plasmons with strong localization along the Schottky contact. We consider Au for the metal stripe, p-doped silicon for the semiconductor, operation in the infrared (at λ<sub>0</sub>=1550  nm), and internal photoemission as the sub-bandgap detection mechanism. We find that the main surface plasmon mode of operation of the Au stripe exhibits diverging real and imaginary parts of n<sub>eff</sub> with decreasing stripe dimensions, commensurate with increasing confinement...
April 20, 2017: Applied Optics
Jeeban Kumar Nayak, Rajan Jha
A graphene-based surface plasmon resonance sensor using D-shaped fiber in anti-crossing has been designed. Silver as a plasmon active metal is followed by graphene, which helps in preventing oxidation and shows better adsorption efficiency to biomolecules. A wavelength interrogation technique based on the finite element method has been used to evaluate performance parameters. Design parameters such as thickness of silver, residual cladding, and GeO<sub>2</sub> dopant concentration have been optimized...
April 20, 2017: Applied Optics
D Y Wan, Y L Zhao, Y Cai, T C Asmara, Z Huang, J Q Chen, J Hong, S M Yin, C T Nelson, M R Motapothula, B X Yan, D Xiang, X Chi, H Zheng, W Chen, R Xu, Ariando, A Rusydi, A M Minor, M B H Breese, M Sherburne, M Asta, Q-H Xu, T Venkatesan
Semiconductor compounds are widely used for photocatalytic hydrogen production applications, where photogenerated electron-hole pairs are exploited to induce catalysis. Recently, powders of a metallic oxide (Sr1-xNbO3, 0.03<x<0.20) were reported to show competitive photocatalytic efficiencies under visible light, which was attributed to interband absorption. This discovery expanded the range of materials available for optimized performance as photocatalysts. Here we study epitaxial thin films of SrNbO3+δ and find that their bandgaps are ∼4...
April 19, 2017: Nature Communications
Debabrata Sikdar, Alwin Bucher, Cristian Zagar, Alexei A Kornyshev
Self-assembling arrays of metallic nanoparticles at liquid|liquid or liquid|solid interfaces could deliver new platforms for tuneable optical systems. Such systems can switch between very-high and very-low reflectance states upon assembly and disassembly of nanoparticles at the interface, respectively. This encourages creation of electro-variably reversible mirror/window nanoplasmonic devices. However, the response time of these systems is usually limited by the rate-of-diffusion of the nanoparticles in the liquid, towards the interface and back...
April 21, 2017: Faraday Discussions
Dandan Tang, Gaoke Zhang
The AgFeO2 delafossite was reported as a potential photocatalyst as well as its intense recombination rate of photogeneration charge carriers. In this work, we utilized plasmon modification method to enhance the photocatalytic activity of AgFeO2. Silkworm cocoon like Ag/AgFeO2 nanocatalyst was synthesized by an ultrasonic enhanced reduction method. XRD, HRTEM and XPS results demonstrated the well dispersed Ag(0) on the surface of AgFeO2. Under visible light irradiation, 20mg/L of ARG solution was completely degraded by 0...
July 2017: Ultrasonics Sonochemistry
Andrea E Schlather, Alejandro Manjavacas, Adam Lauchner, Valeria Spolon Marangoni, Christopher J DeSantis, Peter Nordlander, Naomi J Halas
There is currently a worldwide need to develop efficient photocatalytic materials that can reduce the high energy cost of common industrial chemical processes. One possible solution focuses on metallic nanoparticles (NPs) that can act as efficient absorbers of light due to their surface plasmon resonance. Recent work indicates that small NPs, when photoexcited, may allow for efficient electron or hole transfer necessary for photocatalysis. Here we investigate the mechanisms behind hot hole carrier dynamics by studying the photo-driven oxidation of citrate ions on Au@SiO2@Au core-shell nanoparticles...
April 20, 2017: Journal of Physical Chemistry Letters
Vincenzo Amendola, Roberto Pilot, Marco Frasconi, Onofrio M Maragò, Maria Antonia Iatì
In the last two decades, plasmon resonance in gold nanoparticles (Au NPs) has been the subject of intense research efforts. Plasmon physics is intriguing and its precise modelling proved to be challenging. In fact, plasmons are highly responsive to a multitude of factors, either intrinsic to the Au NPs or from the environment, and recently the need emerged for the correction of standard electromagnetic approaches with quantum effects. Applications related to plasmon absorption and scattering in Au NPs are impressively numerous, ranging from sensing to photothermal effects to cell imaging...
May 24, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Hirokazu Tanoue, Norifumi L Yamada, Kohzo Ito, Hideaki Yokoyama
Polymer brush formation kinetics was measured by quartz crystal microbalance (QCM). In the QCM measurement anomalous complex frequency shift as a function of graft density was observed: dissipation rate shift ΔΓ first increased, showed a peak and then decreased despite the graft density of the polymer brush was increasing monotonically. We calculated the shear modulus of the brush layer from the measured complex frequency shift and revealed that the peak of ΔΓ described the crossover from a viscous brush layer to elastic brush layer...
April 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Wei Ma, Liguang Xu, André F de Moura, Xiaoling Wu, Hua Kuang, Chuanlai Xu, Nicholas A Kotov
The field of chiral inorganic nanostructures is rapidly expanding. It started from the observation of strong circular dichroism during the synthesis of simple nanoparticles (NPs) and their assemblies mediated by biomolecules and expanded to sophisticated synthetic protocols involving nanostructures from metals, semiconductors, ceramics, and nanocarbons. Besides the well-established chirality transfer from bioorganic molecules, other methods to impart handedness to nanoscale matter specific to inorganic materials were discovered, including three-dimentional lithography, multiphoton chirality transfer, polarization effects in nanoscale assemblies, and others...
April 20, 2017: Chemical Reviews
A Le Beulze, S Gomez-Graña, H Gehan, S Mornet, S Ravaine, M Correa-Duarte, L Guerrini, R A Alvarez-Puebla, E Duguet, E Pertreux, A Crut, P Maioli, F Vallée, N Del Fatti, O Ersen, M Treguer-Delapierre
Raspberry-like nano-objects made of large plasmonic satellites (>10 nm) covering a central dielectric particle have many potential applications as photonic materials, superlenses and (bio-) sensors, but their synthesis remains challenging. Herein, we show how to build stable and robust raspberry-like nano-systems with close-packed satellites, by combining monodisperse silica particles (80 or 100 nm diameter) and oppositely charged noble metal nanoparticles (Au or Ag) with well-defined sizes (10-50 nm). The spectral characteristics of their associated plasmonic resonances (wavelength, linewidth, extinction cross-section) and the electromagnetic coupling between satellites were observed using the spatial modulation spectroscopy technique and interpreted through a numerical model...
April 20, 2017: Nanoscale
Weixuan Zhang, Tong Wu, Rongyao Wang, Xiangdong Zhang
We report here the chiroptical amplification effect occurring in the hybrid systems consisting of chiral molecules and Si nanostructures. Under resonant excitation of circularly polarized light, the hybrid systems show strong CD induction signals at the optical frequency, which arise from both the electric and magnetic responses of the Si nanostructures. More interestingly, the induced CD signals from Si-based dielectric nanoantennas are always larger than that from Au-based plasmonic counterparts. The related physical origin was disclosed...
April 20, 2017: Nanoscale
Amr Shebl Ahmed, Hye Jin Kim, Jinsik Kim, Kyo Seon Hwang, Seonghwan Kim
A lead zirconate titanate (PZT;Pb(Zr0.52Ti0.48)O₃) layer embedded infrared (IR) detector decorated with wavelength-selective plasmonic crystals has been investigated for high-performance non-dispersive infrared (NDIR) spectroscopy. A plasmonic IR detector with an enhanced IR absorption band has been designed based on numerical simulations, fabricated by conventional microfabrication techniques, and characterized with a broadly tunable quantum cascade laser. The enhanced responsivity of the plasmonic IR detector at specific wavelength band has improved the performance of NDIR spectroscopy and pushed the limit of detection (LOD) by an order of magnitude...
April 20, 2017: Sensors
Ovidio Peña-Rodríguez, Alejandro Prada, José Olivares, Alicia Oliver, Luis Rodríguez-Fernández, Héctor G Silva-Pereyra, Eduardo Bringa, José Manuel Perlado, Antonio Rivera
In this work we have studied the elongation of silver nanoparticles irradiated with 40 MeV Bromine ions by means of in situ optical measurements, transmission electron microscopy and molecular dynamics simulations. The localized surface plasmon resonance of silver nanoparticles has a strong dependence on the particle shape and size, which allowed us to obtain the geometrical parameters with remarkable accuracy by means of a fit of the optical spectra. Optical results have been compared with transmission electron microscopy images and molecular dynamics simulations and the agreement is excellent in both cases...
April 19, 2017: Scientific Reports
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