Advertisement

Topics

PubMed Journal Database | Nano letters RSS

16:50 EDT 29th March 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 3,300+ from Nano letters

Chemical Transformation of Colloidal Nanostructures with Morphological Preservation by Surface-Protection with Capping Ligands.

When nanocrystals are made to undergo chemical transformations, there are often accompanying large mechanical deformations and changes to overall particle morphology. These effects can constrain development of multistep synthetic methods through loss of well-defined particle morphology and functionality. Here, we demonstrate a surface protection strategy for solution phase chemical conversion of colloidal nanostructures that allows for preservation of overall particle morphology despite large volume changes...

Ultra-low surface recombination velocity in passivated InGaAs/InP nanopillars.

The III-V semiconductor InGaAs is a key material for photonics since it provides optical emission and absorption in the 1.55 μm telecommunication wavelength window. However, InGaAs suffers from pronounced non-radiative effects associated with its surface states, which affect the performance of nanophotonic devices for optical interconnects, namely nanolasers and nanodetectors. This work reports the strong suppression of surface recombination of undoped InGaAs/InP nanostructured semiconductor pillars using ...

Atomic Scale Snapshots of the Formation and Growth of Hollow PtNi/C Nanocatalysts.

Determining the formation and growth mechanism of bimetallic nanoparticles (NPs) with atomic detail is fundamental to synthesize efficient 'catalysts by design'. However, the understanding of the elementary steps, which take place during their synthesis remains elusive. Herein, we have exploited scanning transmission electron microscopy coupled to energy dispersive X-ray spectroscopy, operando wide angle and small angle X-ray scattering and electrochemistry to unveil the formation and growth mechanism of ho...

Ballistic one-dimensional InAs nanowire cross-junction interconnects.

Coherent interconnection of quantum bits remains an ongoing challenge in quantum information technology. Envisioned hardware to achieve this goal is based on semiconductor nanowire (NW) circuits, comprising individual NW devices that are linked through ballistic interconnects. However, maintaining the sensitive ballistic conduction and confinement conditions across NW intersections is a non-trivial problem. Here, we go beyond the characterization of a single NW device and demonstrate ballistic 1D quantum tr...

Morphology and Doping Engineering of Sn-Doped Hematite Nanowire Photoanodes.

High temperature activation has been commonly used to boost the photoelectrochemical (PEC) performance of hematite nanowires for water oxidation, by inducing Sn diffusion from fluorine-doped tin oxide (FTO) substrate into hematite. Yet, hematite nanowires thermally annealed at high temperature suffer from two major drawbacks that negatively affect their performance. First, the structural deformation reduces light absorption capability of nanowire. Second, this "passive" doping method leads to non-uniform di...

Nanoscale Vacuum Channel Transistor.

Vacuum tubes that sparked the electronics era had given way to semiconductor transistors. Despite their faster operation and better immunity to noise and radiation compared to the transistors, the vacuum device technology became extinct due to the high power consumption, integration difficulties, and short lifetime of the vacuum tubes. We combine the best of vacuum tubes and modern silicon nanofabrication technology here. The surround gate nanoscale vacuum channel transistor consists of sharp source and dra...

An ultrafast switchable terahertz polarization modulator based on III--V semiconductor nanowires.

Progress in the terahertz (THz) region of the electromagnetic spectrum is undergoing major advances, with advanced THz sources and detectors being developed at a rapid pace. Yet, ultrafast THz communication is still to be realised, owing to the lack of practical and effective THz modulators. Here, we present a novel ultrafast active THz polarization modulator based on GaAs semiconductor nanowires arranged in a wire-grid configuration. We utilise an optical pump--terahertz probe spectroscopy system and vary ...

Atomic Scale Dynamics of Contact Formation in the Cross-section of InGaAs Nanowire Channels.

Alloyed and compound contacts between metal and semiconductor transistor channels enable self-aligned gate processes which play a significant role in transistor scaling. At nanoscale dimensions and for nanowire channels, prior experiments focused on reactions along the channel length, but the early stage of reaction in their cross-sections remains unknown. Here, we report on the dynamics of the solid-state reaction between metal (Ni) and semiconductor (In0.53Ga0.47As), along the cross-section of nanowires t...

Diode characteristics approaching bulk limits in GaAs nanowire array photodetectors.

We present the electrical properties of p-n junction photodetectors comprised of vertically oriented p-GaAs nanowire arrays on n-GaAs substrate. We measure an ideality factor as low as n = 1.0 and a rectification ratio > 10(8) across all devices, with some > 10(9), comparable to the best GaAs thin film photodetectors. Analysis of the Arrhenius plot of the saturation current yields an activation energy of 690 meV - approximately half the bandgap of GaAs - indicating generation-recombination current from mid-...

Nanoscale imaging of current density with a single-spin magnetometer.

Charge transport in nanostructures and thin films is fundamental to many phenomena and processes in science and technology, ranging from quantum effects and electronic correlations in mesoscopic physics, to integrated charge- or spin-based electronic circuits, to photoactive layers in energy research. Direct visualization of the charge flow in such structures is challenging due to their nanometer size and the itinerant nature of currents. In this work, we demonstrate non-invasive magnetic imaging of current...

Twisting Fluorescence through Extrinsic Chiral Antennas.

Plasmonic antennas and planar structures have been undergoing intensive developments in order to control the scattering and absorption of light. One specific class, extrinsic chiral surfaces, that does not possess twofold rotational symmetry exhibits strong asymmetric transmission for different circular polarizations under obliquely incident illumination. In this work, we show that the design of those surfaces can be optimized with complex multipolar resonances in order to twist the fluorescence emission fr...

Correlating Carrier Density and Emergent Plasmonic Features in Cu2-xSe Nanoparticles.

Recently, a wide variety of new nanoparticle compositions have been identified as potential plasmonic materials including earth-abundant metals such as aluminum, highly doped semiconductors, as well as metal pnictides. For semiconductor compositions, plasmonic properties may be tuned not only by nanoparticle size and shape, but also by charge carrier density which can be controlled via a variety of intrinsic and extrinsic doping strategies. Current methods to quantitatively determine charge carrier density ...

Coulomb Blockade Plasmonic Switch.

Tunnel resistance can be modulated by the bias voltage via the Coulomb blockade effect, which gives a highly nonlinear response current. Here we investigate the optical response of metal-insulator-nanoparticle-insulator-metal structure and show switching of plasmonic gap from insulator to conductor via conquering Coulomb blockade. By introducing a sufficiently large charging energy in tunnelling gap, the Coulomb blockade allows for a metal (tunneling) to insulator (capacitor) transition. The tunnelling elec...

Revealing the Electronic Structure of Silicon Intercalated Armchair Graphene Nanoribbons by Scanning Tunneling Spectroscopy.

The electronic properties of graphene nanoribbons grown on metal substrates are significantly masked by the ones of the supporting metal surface. Here, we introduce a novel approach to access the frontier states of armchair graphene nanoribbons (AGNRs). The in situ intercalation of Si at the AGNR/Au(111) interface through surface alloying suppresses the strong contribution of the Au(111) surface state and allows for an unambiguous determination of the frontier electronic states of both wide and narrow band ...

Opto-mechanics of single aluminum nanodisks.

Aluminum nanostructures support tunable surface plasmon resonances and have become an alternative to gold nanoparticles. While gold is the most-studied plasmonic material, aluminum has the advantage of high earth abundance and hence low cost. In addition to understanding the size and shape tunability of the plasmon resonance, the fundamental relaxation processes in aluminum nanostructures after photo-excitation must be understood, to take full advantage of applications such as photocatalysis and photodetect...

Nanoimprint-Transfer-Patterned Solids Enhance Light Absorption in Colloidal Quantum Dot Solar Cells.

Colloidal quantum dot (CQD) materials are of interest in thin-film solar cells due to their size-tunable bandgap and low-cost solution-processing. However, CQD solar cells suffer from inefficient charge extraction over the film thicknesses required for complete absorption of solar light. Here we show a new strategy to enhance light absorption in CQD solar cells by nanostructuring the CQD film itself at the back interface. We use two-dimensional finite-difference time-domain (FDTD) simulations to study quant...

Mediating Passive Tumor Accumulation through Particle Size, Tumor Type and Location.

As the enhanced permeation and retention (EPR) effect continues to be a controversial topic in nanomedicine, we sought to examine EPR as a function of nanoparticle size, tumor model and tumor location, while also evaluating tumors for EPR mediating factors such as microvessel density, vascular permeability, lymphatics, stromal content, and tumor associated immune cells. Tumor accumulation was evaluated for 55x60 nm, 80x180 nm, and 80x320 nm PRINT particles, in four subcutaneous flank tumor models (SKOV3 hum...

Heterogeneous pyrolysis: a route for epitaxial growth of hBN atomic layers on copper using separate boron and nitrogen precursors.

Growth of hBN on metal substrates is often performed via chemical vapor deposition from a single precursor (e.g., borazine), and results in hBN monolayers limited by the substrates catalyzing effect. Departing from this paradigm, we demonstrate close control over the growth of mono- , bi-, and trilayers of hBN on copper using triethylborane and ammonia as independent sources of boron and nitrogen. Using density functional theory (DFT) calculations and reactive force field molecular dynamics, we show that th...

Design of heterogeneous chalcogenide nanostructures with pressure-tunable gaps and without electronic trap states.

Heterogeneous nanostructures, such as quantum dots (QDs) embedded in solid matrices or core-shell nanoparticles, are promising platforms for a wide variety of applications, including phosphors with increased quantum yield, photocatalysis and solar energy conversion. However characterizing and controlling their interfacial morphology and defects, which greatly influence their electronic properties, have proven difficult in numerous cases. Here we carried out atomistic calculations on chalcogenides nanostruct...

Assessment of Gold Nano-particle mediated Enhanced Hyperthermia using MR Guided High-Intensity Focused Ultrasound Ablation Procedure.

High-intensity focused ultrasound (HIFU) has gained increasing popularity as a non-invasive therapeutic procedure to treat solid tumors. However, collateral damage due to the use of high acoustic powers during HIFU procedures remains a challenge. The objective of this study is to assess the utility of using gold nano-particles (gNPs) during HIFU procedures to locally enhance heating at low powers, thereby reducing the likelihood of collateral damage. Phantoms containing tissue-mimicking material (TMM) and p...

Colossal terahertz magnetoresistance at room temperature in epitaxial La0.7Sr0.3MnO3 nanocomposites and single-phase thin films.

Colossal magnetoresistance (CMR) is demonstrated at terahertz (THz) frequencies by using terahertz time-domain magnetospectroscopy to examine nanocolumns and planar thin films of La0.7Sr0.3MnO3. At the metal-insulator transition the THz conductivity of the nanocolumn film was dramatically enhanced by the application of a magnetic field, creating a non-Drude conductivity that increased with frequency. The colossal magnetoresistance at 1.0THz is -99.9% at the Curie temperature (room temperature), far exceedin...

Boron Doping of Multi-walled Carbon Nanotubes Significantly Enhances Hole Extraction in Carbon-based Perovskite Solar Cells.

Compared with the conventional perovskite solar cells (PSCs) containing hole-transport materials (HTM), carbon materials based HTM-free PSCs (C-PSCs) have often suffered from inferior power conversion efficiencies (PCEs) arising at least partially from the inefficient hole extraction at perovskite/carbon interface. Here, we show that boron (B) doping of multi-walled carbon nanotubes (B-MWNTs) electrodes are superior in enabling enhanced hole extraction and transport by increasing work function, carrier conc...

Defect Coupling and Sub-Angstrom Structural Distortions in W1-xMoxS2 Monolayers.

Two-dimensional materials offer a remarkably rich materials platform to study the origin of different material behaviors at the atomic level, and doping provides a key means of tailoring such materials' functional properties. The local atomic structure around such dopants can be critically important in determining the material behavior as it could modulate scattering, catalytic activity, electronic and magnetic properties, etc. Here, using aberration-corrected scanning transmission electron microscopy with ...

Efficient Third Harmonic Generation from Metal-Dielectric Hybrid Nanoantennas.

High refractive index dielectric nanoantennas are expected to become key elements for nonlinear nano-optics applications due to their large nonlinearities, low energy losses and ability to produce high electric field enhancements in relatively large nanoscale volumes. In this work, we show that the nonlinear response from a high-index dielectric nanoantenna can be significantly improved by adding a metallic component to build metal-dielectric hybrid nanostructures. We demonstrate that the plasmonic resonanc...

Robust whispering-gallery-mode microbubble lasers from colloidal quantum dots.

Microlasers hold great promise for the development of photonics and optoelectronics. Among the discovered optical gain materials, colloidal quantum dots (CQDs) have been recognized as the most appealing candidate due to the facile emission tunability and solution processibility. However, to date, it is still challenging to develop CQD-based microlasers with low cost yet high performance. Moreover, the poor long-term stability of CQDs remains to be the most critical issue, which may block their laser aspirat...


Quick Search
Advertisement