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PubMed Journal Database | Nano letters RSS

03:35 EDT 26th September 2017 | BioPortfolio

The US National Library of Medicine and National Institutes of Health manage PubMed.gov which comprises of more than 21 million records, papers, reports for biomedical literature, including MEDLINE, life science and medical journals, articles, reviews, reports and  books.  BioPortfolio aims to publish relevant information on published papers, clinical trials and news associated with users selected topics.

For example view all recent relevant publications on Epigenetics and associated publications and clincial trials.

Showing PubMed Articles 1–25 of 3,600+ from Nano letters

Terahertz Light-Matter Interaction beyond Unity Coupling Strength.

Achieving control over light-matter interaction in custom-tailored nanostructures is at the core of modern quantum electrodynamics. In strongly and ultrastrongly coupled systems, the excitation is repeatedly exchanged between a resonator and an electronic transition at a rate known as the vacuum Rabi frequency ΩR. For ΩR approaching the resonance frequency ωc, novel quantum phenomena including squeezed states, Dicke superradiant phase transitions, the collapse of the Purcell effect, and a population of t...

Giant enhancement of cathodoluminescence of monolayer transitional metal dichalcogenides semiconductors.

Monolayer two-dimensional transitional metal dichalcogenides, such as MoS2, WS2 and WSe2, are direct band gap semiconductors with large exciton binding energy. They attract growing attentions for opto-electronic applications including solar cells, photo-detectors, light-emitting diodes and photo-transistors, capacitive energy storage, photodynamic cancer therapy and sensing on flexible platforms. While light-induced luminescence has been widely studied, luminescence induced by injection of free electrons co...

Contact dependence and velocity crossover in friction between microscopic solid/solid contacts.

Friction at the nanoscale differs markedly from that between surfaces of macroscopic extent. Characteristically, the velocity dependence of friction between apparent solid/solid contacts can strongly deviate from the classically assumed velocity independence. Here, we show that a non-destructive friction between solid tips with radius on the scale of hundreds of nanometers, and solid, hydrophobic selfassembled monolayers has a strong velocity dependence. Specifically, using laterally oscillatingquartztuni...

Copper sulfide perfluorocarbon nanodroplets as clinically relevant photoacoustic/ultrasound imaging agents.

We have developed laser-activated perfluorocarbon nanodroplets containing copper sulfide nanoparticles (CuS NPs) for contrast-enhanced ultrasound and photoacoustic imaging. As potential clinical contrast agents, CuS NPs have favorable properties including biocompatibility, biodegradability and enhance contrast in photoacoustic images at clinically relevant depths. However, CuS NPs are not efficient optical absorbers when compared to plasmonic nanoparticles and therefore, contrast enhancement with CuS NPs is...

An Ultra-Thin Nanoporous Membrane Evaporator.

Evaporation is a ubiquitous phenomenon found in nature and widely used in industry. Yet fundamental understanding of interfacial transport during evaporation remains limited to date owing to the difficulty of characterizing the heat and mass transfer at the interface, especially at high heat fluxes ( > 100 W/cm(2)). In this work, we elucidated evaporation into an air ambient with an ultra-thin (≈ 200 nm thick) nanoporous (≈ 130 nm pore diameter) membrane. With our evaporator design, we accurately monito...

Collective lasing behavior of monolithic GaN-InGaN core-shell nanorod lattice under room temperature.

We demonstrated a monolithic GaN-InGaN core-shell nanorod lattice lasing under room temperature. The threshold pumping density was as low as 140 kW/cm2 with a quality factor as high as 1940. The narrow mode spacing between lasing peaks suggested a strong coupling between adjacent whisper gallery modes (WGM), which was confirmed with the far-field patterns. Excitation area dependent photoluminescence revealed that the long-wavelength lasing modes dominated the collective lasing behavior under a large excitat...

Mapping Photoemission and Hot-Electron Emission from Plasmonic Nanoantennas.

Understanding plasmon-mediated electron emission and energy transfer on the nanometer length scale is critical to controlling light-matter interactions at nanoscale dimensions. In a high-resolution lithographic material, electron emission and energy transfer lead to chemical transformations. In this work, we employ such chemical transformations in two different high-resolution electron-beam lithography resists, poly(methyl methacrylate) (PMMA) and hydrogen silsesquioxane (HSQ), to map local electron emissio...

Polypyrrole Coated Perfluorocarbon Nanoemulsions as a Sono-Photoacoustic Contrast Agent.

A new contrast agent for combined photoacoustic and ultrasound imaging is presented. It has a liquid perfluorocarbon (PFC) core of about 250 nm diameter coated by a 30 nm thin polypyrrole (PPy) doped polymer shell emulsion which represents a broadband absorber covering the visible and near-infrared ranges (peak optical extinction at 1050 nm). When exposed to a sufficiently high intensity optical or acoustic pulse, the droplets vaporize to form microbubbles providing a strong increase in imaging sensitivity ...

Planar Optical Nano-Antennas Resolve Cholesterol-Dependent Nanoscale Heterogeneities in the Plasma Membrane of Living Cells.

Optical nano-antennas can efficiently confine light into nanoscopic hotspots enabling single-molecule detection sensitivity at biological relevant conditions. This innovative approach to breach the diffraction limit offers a versatile platform to investigate the dynamics of individual biomolecules in living cell membranes and their partitioning into cholesterol-dependent lipid nanodomains. Here, we present optical nano-antenna arrays with accessible surface hotspots to study the characteristic diffusion dyn...

Optical Forging of Graphene into Three-Dimensional Shapes.

Atomically thin materials, such as graphene, are the ultimate building blocks for nanoscale devices. But although their synthesis and handling today are routine, all efforts thus far have been restricted to flat natural geometries, since the means to control their three-dimensional (3D) morphology has remained elusive. Here we show that, just as a blacksmith uses a hammer to forge a metal sheet into 3D shapes, a pulsed laser beam can forge graphene sheet into controlled 3D shapes in the nanoscale. The forgi...

Anisotropic Cracking of Nanocrystal Superlattices.

The synthesis colloidal nanocrystals in non-polar organic solvents has led to exceptional size- and shape-control, enabling the formation of nanocrystal superlattices isostructural to atomic lattices built with nanocrystals rather than atoms. The long aliphatic ligands (e.g. oleic acid) used to achieve this control separate nanocrystals too far in the solid-state for most charge-transporting devices. Solid-state ligand exchange, which brings particles closer together and enhances conductivity, necessitates ...

Phonon Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface.

The van der Waals (vdW) interfaces of two-dimensional (2D) semiconductor are central to new device concepts and emerging technologies in light-electricity transduction where the efficient charge separation is a key factor. Contrary to general expectation, efficient electron-hole separation can occur in vertically stacked transition-metal dichalcogenide (TMD) heterostructure bilayers through ultrafast charge transfer between the neighboring layers despite their weak vdW bonding. In this report, we show by ab...

Gigahertz optomechanical modulation by split-ring-resonator nanophotonic meta-atom arrays.

Using polarization-resolved transient reflection spectroscopy, we investigate the ultrafast modulation of light interacting with a metasurface consisting of coherently vibrating nanophotonic meta-atoms in the form of U-shaped split-ring resonators, that exhibit co-localized optical and mechanical resonances. With a two-dimensional square-lattice array of these resonators formed of gold on a glass substrate, we monitor the visible-pump-pulse induced gigahertz oscillations in intensity of reflected linearly-p...

Hydration friction in nano-confinement: from bulk via interfacial to dry friction.

The viscous properties of nanoscopically confined water are important when hydrated surfaces in close contact are sheared against each other. Numerous experiments have probed the friction between atomically flat hydrated surfaces in the sub-nanometer separation regime and suggested an increased water viscosity, but the value of the effective viscosity of ultra-confined water, the mechanism of hydration layer friction and the crossover to the dry friction limit are unclear. We study the shear friction betwee...

Enhancing organic semiconductor-surface plasmon polariton coupling with molecular orientation.

Due to strong electric field enhancements, surface plasmon polaritons (SPPs) are capable of drastically increasing light-molecule coupling in organic optoelectronic devices. The electric field enhancement, however, is anisotropic, offering maximal functional benefits if molecules are oriented perpendicular to the interface. To provide a clear demonstration of this orientation dependence, we study SPP dispersion and SPP-mediated photoluminescence at a model Au/small-molecule interface where identical molecul...

Te monolayer-driven spontaneous van der Waals epitaxy of two-dimensional pnictogen chalcogenide film on sapphire.

Demands on high-quality layer structured two-dimensional (2D) thin films such as pnictogen chalcogenides and transition metal dichalcogenides are growing due to the findings of exotic physical properties and potentials for device applications. However, the difficulties in controlling epitaxial growth and the unclear understanding of van der Waals epitaxy (vdWE) for 2D chalcogenide film on three-dimensional (3D) substrate have been major obstacles for the further advances of 2D materials. Here, we exploit th...

Asymmetric nanoantennas for ultra-high angle broadband visible light bending.

Wavefront manipulation in metasurfaces typically relies on phase mapping with a finite number of elements. In particular, a discretized linear phase profile may be used to obtain a beam bending functionality. However, discretization limits the applicability of this approach for high angle bending due to the drastic efficiency drop when the phase is mapped by a small number of elements. In this work, we discuss a novel concept for energy redistribution in diffraction gratings and its application in the visib...

Theoretical Discovery of Superconducting Two-Dimensional Metal-Organic Framework.

Superconductivity is a fascinating quantum phenomenon characterized by zero electrical resistance and the Meissner effect. To date, several distinct families of superconductors (SCs) have been discovered. These include three-dimensional (3D) bulk SCs in both inorganic and organic materials as well as two-dimensional (2D) thin film SCs but only in inorganic materials. Here we predict superconductivity in 2D and 3D organic metal-organic frameworks by using first-principles calculations. We show that the highl...

A novel intrinsic interface state controlled by atomic stacking sequence at interfaces of SiC/SiO2.

On the basis of ab-initio total-energy electronic-structure calculations, we find that electron states localized at the SiC/SiO2 interface emerge in the energy region between 0.3 eV below and 1.2 eV above the bulk conduction-band minimum (CBM) of SiC, being sensitive to the sequence of atomic bilayers in SiC near the interface. These new interface states unrecognized in the past are due to the peculiar characteristics of the CBM states which are distributed along the crystallographic channels. We also find ...

Directed Two-Photon Absorption in CdSe Nanoplatelets Revealed by k-Space Spectroscopy.

We show that two-photon absorption (TPA) is highly anisotropic in CdSe nanoplatelets, thus promoting them as a new class of directional two-photon absorbers with large cross-sections. Comparing two-dimensional k-space spectroscopic measurements of the one-photon and two-photon excitation of an oriented monolayer of platelets, it is revealed that TPA into the continuum is a directional phenomenon. This is in contrast to one-photon absorption. The observed directional TPA is shown to be related to fundamental...

Micrometre-sized magnesium whitlockite crystals in micropetrosis of bisphosphonate-exposed human alveolar bone.

Osteocytes are contained within spaces called lacunae and play a central role in bone remodelling. Administered frequently to prevent osteoporotic fractures, anti-resorptive agents such as bisphosphonates suppress osteocyte apoptosis and may be localised within osteocyte lacunae. Bisphosphonates also reduce osteoclast viability, and thereby hinder the repair of damaged tissue. Osteocyte lacunae contribute to toughening mechanisms. Following osteocyte apoptosis, the lacunar space undergoes mineralisation, te...

Crystal phase quantum well emission with digital control.

One of the major challenges in the growth of quantum well and quantum dot heterostructures is the realization of atomically sharp interfaces. Nanowires provide a new opportunity to engineer the band structure as they facilitate the controlled switching of the crystal structure between the zinc-blende (ZB) and wurtzite (WZ) phases. Such a crystal phase switching results in the formation of crystal phase quantum wells (CPQWs) and quantum dots (CPQDs). For GaP CPQWs, the inherent electric fields due to the dis...

GaN metalens for pixel-level full-color routing at visible light.

Metasurface-based components are known to be one of the promising candidates for developing flat optical systems. However, their low working efficiency highly limits the use of such flat components for feasible applications. Although the introduction of the metallic mirror has been demonstrated to successfully enhance the efficiency, it is still somehow limited for imaging and sensing applications because they are only available for devices operating in a reflection fashions. Here, we demonstrate three indi...

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals.

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating ...

Functional Circuitry on Commercial Fabric via Textile-Compatible Nanoscale Film Coating Process for Fibertronics.

Fabric-based electronic textiles (e-textiles) are the fundamental components of wearable electronic systems, which can provide convenient hand-free access to computer and electronics applications. However, e-textile technologies presently face significant technical challenges. These challenges include difficulties of fabrication due to the delicate nature of the materials, and limited operating time, a consequence of the conventional normally-on computing architecture, with volatile power-hungry electronic ...


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