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PubMed Journal Database | Nano letters RSS

16:30 EST 19th January 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.

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Showing PubMed Articles 1–25 of 3,200+ from Nano letters

Novel Two-Dimensional Silicon Dioxide with in-plane Negative Poisson's Ratio.

Silicon dioxide or silica, normally existing in various bulk crystalline and amorphous forms, is recently found to possess a two-dimensional structure. In this work, we use ab initio calculation and evolutionary algorithm to unveil three new 2D silica structures whose themal, dynamical and mechanical stabilities are compared with many typical bulk silica. In particular, we find that all these three 2D silica have large in-plane negative Poisson's ratios with the largest one being double of penta-graphene an...

Level Spectrum and Charge Relaxation in a Silicon Double Quantum Dot Probed by Dual-Gate Reflectometry.

We report on dual-gate reflectometry in a metal-oxide-semiconductor double-gate silicon transistor operating at low temperature as a double quantum dot device. The reflectometry setup consists of two radio frequency resonators respectively connected to the two gate electrodes. By simultaneously measuring their dispersive responses, we obtain the complete charge stability diagram of the device. Electron transitions between the two quantum dots and between each quantum dot and either the source or the drain c...

Solution Synthesis of Iodine-Doped Red Phosphorus Nanoparticles for Lithium-Ion Battery Anodes.

Red Phosphorus (RP) is a promising anode material for lithium-ion battery due to its earth abundance and a high theoretical capacity of 2596 mA h g-1. Although RP-based anodes for lithium-ion batteries have been reported, they were all in the form of carbon/P composites, including P-graphene, P-graphite, P-CNTs and P-carbon black, in order to improve P's extremely low conductivity and large volume change during cycling process. Here we report the large-scale synthesis of red phosphorus nanoparticles (RPNPs)...

Nanoscale Engineering in VO2 nanowires via Direct Electron Writing Process.

Controlling phase transition in functional materials at nano-scale is not only of broad scientific interest, but also important for practical applications in the fields of renewable energy, information storage, transducer, sensor, etc. As a model functional material, vanadium dioxide (VO2) has its metal-insulator transition (MIT) usually at a sharp temperature around 68 °C. Here we report a focused electron beam can directly lower down the transition temperature of a nano-area to room temperature without p...

Formation of nickel clusters wrapped in carbon cages: towards new endohedral metallofullerene synthesis.

In spite of the high potential of endohedral metallofullerenes (EMFs) for application in biology, medicine and molecular electronics and recent efforts in EMF synthesis, the variety of EMFs accessible by conventional synthetic methods remains limited and does not include, for example, EMFs of late transition metals. We propose a method in which EMF formation is initiated by electron irradiation in aberration-corrected high-resolution transmission electron spectroscopy (AC-HRTEM) of a metal cluster surrounde...

High-Curvature Nanostructuring Enhances Probe Display for Biomolecular Detection.

High-curvature electrodes facilitate rapid and sensitive detection of a broad class of molecular analytes. These sensors have reached detection limits not attained using bulk macroscale materials. It has been proposed that immobilized DNA probes are displayed at a high deflection angle on the sensor surface, allowing greater accessibility and more efficient hybridization. Here we report the first use of all-atom molecular dynamics simulations coupled with electrochemical experiments to explore the dynamics ...

Yeast Microcapsule-Mediated Targeted Delivery of Diverse Nanoparticles for Imaging and Therapy via the Oral Route.

Targeting of nanoparticles to distant diseased sites after oral delivery remains highly challenging, due to the existence of many biological barriers in the gastrointestinal tract. Here we report targeted oral delivery of diverse nanoparticles in multiple disease models, via a 'Trojan horse' strategy based on a bioinspired yeast capsule (YC). Diverse charged nanoprobes including quantum dots (QDs), iron oxide nanoparticles (IONPs), and assembled organic fluorescent nanoparticles can be effectively loaded in...

Stereoelectronic Effect-Induced Conductance Switching in Aromatic Chain Single-Molecule Junctions.

Biphenyl, as the elementary unit of organic functional materials, has been widely used in electronic and optoelectronic devices. However, over decades little has been fundamentally understood regarding how the intramolecular conformation of biphenyl dynamically affects its transport properties at the single-molecule level. Here, we establish the stereoelectronic effect of biphenyl on its electrical conductance based on the platform of graphene-molecule single-molecule junctions, where a specifically-designe...

Side gate tunable Josephson junctions at the LaAlO3/SrTiO3 interface.

Novel physical phenomena arising at the interface of complex oxide heterostructures offer exciting opportunities for the development of future electronic devices. Using the prototypical LaAlO3/SrTiO3 interface as a model system, we employ a single-step lithographic process to realize gate tunable Josephson junctions through a combination of lateral confinement and local side gating. The action of the side gates is found to be comparable to that of a local back gate, constituting a robust and efficient way t...

Proximity Effect Transfer from NbTi into a Semiconductor Heterostructure via Epitaxial Aluminum.

We demonstrate the transfer of the superconducting properties of NbTi---a large-gap high-critical-field superconductor---into an InAs heterostructure via a thin intermediate layer of epitaxial Al. Two device geometries, a Josephson junction and a gate-defined quantum point contact, are used to characterize interface transparency and the two-step proximity effect. In the Josephson junction, multiple Andreev reflection reveal near-unity transparency, with an induced gap Δ*=0.50 meV and a critical temperature...

Insights into the Distinct Lithiation/Sodiation of Porous Cobalt Oxide by in Operando Synchrotron X-ray Techniques and ab initio Molecular Dynamics Simulations.

Sodium-ion batteries (SIBs) have been considered as one of the promising power source candidates for the stationary storage industries owing to the much lower cost of sodium than lithium. It's well known that the electrode materials largely determine the energy density of the battery systems. However, recent discoveries on the electrode materials showed that most of them present distinct lithium and sodium storage performance, which is not yet well understood. In this work, we performed a comparative unders...

Nanoscale Nucleation and Growth of Electrodeposited Lithium Metal.

Lithium metal has re-emerged as an exciting anode for high energy lithium-ion batteries due to its high specific capacity of 3,860 mAh g(-1) and lowest electrochemical potential of all known materials. However, lithium has been plagued by the issues of dendrite formation, high chemical reactivity with electrolyte, and infinite relative volume expansion during plating and stripping, which present safety hazards and low cycling efficiency in batteries with lithium metal electrodes. There have been a lot of re...

Three-Dimensional Integration of Black Phosphorus Photodetector with Silicon Photonics and Nanoplasmonics.

We demonstrate the integration of black phosphorus photodetector in a hybrid, three-dimensional architecture of silicon photonics and metallic nanoplasmonics structures. This integration approach combines the advantages of low propagation loss of silicon waveguides, high field confinement of a plasmonic nanogap, and the narrow bandgap of black phosphorus to achieve high responsivity for detection of telecom-band near-infrared light. Benefitting from an ultrashort channel (~60 nm) and near-field enhancement ...

Coherent phonon Rabi oscillations with a high frequency carbon nanotube phonon cavity.

Phonon-cavity electromechanics allows the manipulation of mechanical oscillations similar to photon-cavity systems. Many advances on this subject have been achieved in various materials. In addition, the coherent phonon transfer (phonon Rabi oscillations) between the phonon cavity mode and another oscillation mode has attracted many interest in nano-science. Here we demonstrate coherent phonon transfer in a carbon nanotube phonon-cavity system with two mechanical modes exhibiting strong dynamical coupling. ...

Directed Self-Assembly of Polystyrene-b-poly(propylene carbonate) on Chemical Patterns via Thermal Annealing for Next-Generation Lithography.

Directed self-assembly (DSA) of block copolymers (BCPs) combines advantages of conventional photolithography and polymeric materials and shows competence in semiconductors and data storage applications. Driven by the more integrated, much smaller and higher performance of the electronics, however, the industry standard polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) in DSA strategy cannot meet the rapid development of lithography technology because its intrinsic limited Flory-Huggins interaction par...

Core/Shell Nanocomposites Produced by Superfast Sequential Microfluidic Nanoprecipitation.

Although a number of techniques exist for generating structured organic nanocomposites, it is still challenging to fabricate them in a controllable, yet universal and scalable manner. In this work, a microfluidic platform, exploiting superfast (milliseconds) time intervals between sequential nanoprecipitation processes, has been developed for high-throughput production of structured core/shell nanocomposites. The extremely short time interval between the sequential nanoprecipitation processes, facilitated b...

Integration of Quantum Confinement and Alloy Effect to Modulate Electronic Properties of RhW Nanocrystals for Improved Catalytic Performance towards CO2 Hydrogenation.

The d-band center and surface negative charge density generally determine the adsorption and activation of CO2, thus serving as important descriptors of the catalytic activity towards CO2 hydrogenation. Herein, we engineered the d-band center and negative charge density of Rh-based catalysts by tuning their dimensions and introducing non-noble metals to form an alloy. During the hydrogenation of CO2 into methanol, the catalytic activity of Rh75W25 nanosheets was 5.9, 4.0, and 1.7 times as high as that of Rh...

Quantum-Confined and Enhanced Optical Absorption of Colloidal PbS Quantum Dots at Wavelengths with Expected Bulk Behavior.

Nowadays it is well-accepted to attribute bulk-like optical absorption properties to colloidal PbS quantum dots (QDs) at wavelengths above 400 nm. This assumption permits to describe PbS QD light absorption by using bulk optical constants and to determine QD concentration in colloidal solutions from simple spectrophotometric measurements. Here we demonstrate that PbS QDs experience the quantum confinement regime across the entire near UV-Vis-NIR spectral range, therefore also between 350 and 400 nm already ...

Discovering A First-order Phase Transition in Li-CeO2 System.

An in-depth understanding of (de)lithiation induced phase transition in electrode materials is crucial to grasp their structure-property relationships and provide guidance to the design of more desirable electrodes. By operando synchrotron XRD (SXRD) measurement and Density Functional Theory (DFT) based calculations, we discover a reversible first-order phase transition for the first time during (de)lithiation of CeO2 nanoparticles. The LixCeO2 compound phase is identified to possess the same fluorite cryst...

Critical Behavior in Doping-Driven Metal-Insulator Transition on Single-Crystalline Organic Mott-FET.

We present the carrier transport properties in the vicinity of a doping-driven Mott transition observed at a field-effect transistor (FET) channel using a single crystal of the typical two-dimensional organic Mott insulator κ-(BEDT-TTF)2CuN(CN)2Cl (κ-Cl). The FET shows a continuous metal-insulator transition (MIT) as electrostatic doping proceeds. The phase transition appears to involve two-step crossovers, one in Hall measurement and the other in conductivity measurement. The crossover in conductivity oc...

Spin orientation of two-dimensional electrons driven by temperature-tunable competition of spin-orbit and exchange magnetic interactions.

Finding ways to create and control the spin-dependent properties of two-dimensional electron states (2DESs) is a major challenge for the elaboration of novel spin-based devices. Spin-orbit and exchange-magnetic interactions (SOI & EMI) are two fundamental mechanisms that enable access to the tunability of spin-dependent properties of carriers. The silicon surface of HoRh2Si2 appears to be a unique model system, where concurrent SOI and EMI can be visualized and controlled by varying the temperature. The bea...

Torsional Resonators Based on Inorganic Nanotubes.

We study for the first time the resonant torsional behaviors of inorganic nanotubes, specifically tungsten disulfide (WS2) and boron nitride (BN) nanotubes, and compare them to that of carbon nanotubes. We have found WS2 nanotubes to have the highest quality factor (Q) and torsional resonance frequency, followed by BN nanotubes and carbon nanotubes. Dynamic and static torsional spring constants of the various nanotubes were found to be different, especially in the case of WS2, possibly due to a velocity-dep...

Tunable positive to negative magnetoresistance in atomically thin WTe2.

Transitional metal ditelluride WTe2 has been extensively studied owing to its intriguing physical properties like non-saturating positive magnetoresistance and being possibly a type-II Weyl semimetal. While surging research activities were devoted to the understanding of its bulk properties, it remains a substantial challenge to explore the pristine physics in atomically thin WTe2. Here, we report a successful synthesis of mono- to few-layer WTe2 via chemical vapor deposition. Using atomically thin WTe2 nan...

Enhanced Structural Stability of Nickel-Cobalt Hydroxide via Intrinsic Pillar Effect of Metaborate for High-Power and Long-Life Supercapacitor Electrodes.

Layered α-Ni(OH)2 and its derivative bimetallic hydroxides (e.g., α-(Ni/Co)(OH)2) have attracted much attention due to their high specific capacitance, although their insufficient cycling stability has blocked their wide application in various technologies. In this work, we demonstrate that the cycling performance of α-(Ni/Co)(OH)2 can be obviously enhanced via the intrinsic pillar effect of metaborate. Combining the high porosity feature of the metaborate stabilized α-(Ni/Co)(OH)2 and the improved elec...

The Use of Graphene and Its Derivatives for Liquid-Phase Transmission Electron Microscopy of Radiation-Sensitive Specimens.

One of the key challenges facing liquid-phase transmission electron microscopy (TEM) of biological specimens has been the damaging effects of electron beam irradiation. The strongly ionizing electron beam is known to induce radiolysis of surrounding water molecules, leading to the formation of reactive radical species. In this study, we employ DNA-assembled Au nanoparticle superlattices (DNA-AuNP superlattices) as a model system to demonstrate that graphene and its derivatives can be used to mitigate electr...


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