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PubMed Journal Database | Nano letters RSS

15:00 EDT 28th September 2016 | 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 3,100+ from Nano letters

Al-Pd Nanodisk Heterodimers as Antenna-Reactor Photocatalysts.

Photocatalysis uses light energy to drive chemical reactions. Conventional industrial catalysts are made of transition metal nanoparticles that interact only weakly with light, while metals such as Au, Ag, and Al that support surface plasmons interact strongly with light but are poor catalysts. By combining plasmonic and catalytic metal nanoparticles, the plasmonic "antenna" can couple light into the catalytic "reactor". This interaction induces an optical polarization in the reactor nanoparticle, forcing a...

Ternary FexCo1-xP Nanowire Array as a Robust Hydrogen Evolution Reaction Electrocatalyst with Pt-like Activity: Experimental and Theoretical Insight.

Replacement of precious Pt with earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) holds great promise for clean energy devices, but the development of low-cost and durable HER catalysts with Pt-like activity is still a huge challenge. In this communication, we report on the development of self-standing ternary FexCo1-xP nanowire array on carbon cloth (FexCo1-xP/CC) as a Pt-free HER catalyst with activities being strongly related to Fe substitution ratio. Electrochemical tests show th...

Value and Anisotropy of the Electron and Hole Mass in Pure Wurtzite InP Nanowires.

The effective mass of electrons and holes in semiconductors is pivotal in determining the dynamics of carriers and their confinement energy in nanostructured materials. Surprisingly, this quantity is still unknown in wurtzite (WZ) nanowires (NWs) made of III-V compounds (e.g., GaAs, InAs, GaP, InP), where the WZ phase has no bulk counterpart. Here, we investigate the magneto-optical properties of InP WZ NWs grown by selective-area epitaxy that provides perfectly ordered NWs featuring high-crystalline qualit...

Graphene as a promising electrode for low current attenuation in asymmetric molecular junctions.

We have measured the single molecule conductance of 1,n-alkanedithiol molecular bridges (n = 4, 6, 8, 10, 12) on a graphene substrate using STM formed electrical junctions. The conductance values of this homologous series ranged from 2.3 nS (n=12) to 53 nS (n=4), with a decay constant βN of 0.40 per methylene (-CH2) group. This result is explained by a combination of density functional theory (DFT) and Keldysh-Green function calculations. The obtained decay, which is much lower than the one obtained for sy...

Atomistic design of CdSe/CdS core-shell quantum dots with suppressed Auger recombination.

We design quasi-type-II CdSe/CdS core-shell colloidal quantum dots (CQDs) ex- hibiting a suppressed Auger recombination rate. We do so using fully atomistic tight- binding wavefunctions and microscopic Coulomb interactions. The recombination rate as a function of the core and shell size and shape is tested against experiments. Due to a higher density of deep hole states and stronger hole confinement, Auger recombi- nation is found to be up to six times faster for positive trions compared to negative ones in...

Engineering topological surface states of Cr-doped Bi2Se3 films by spin reorientation and electric field.

Tailoring of topological surface states in topological insulators is essential for device applications and for exploring new topological phase. Here, we propose a practical way to induce the quantum anomalous Hall phase and unusual metal-insulator transition in Cr-doped Bi2Se3 films based on model Hamiltonian and the first-principles calculations. Using the combination of in-plane and plane-normal components of the spin along with external electric fields, we demonstrate that the topological state and band ...

A Nanoscale Tool for Photoacoustic-based Measurements of Clotting Time and Therapeutic Drug Monitoring of Heparin.

Heparin anticoagulation therapy is an indispensable feature of clinical care yet has a narrow therapeutic window and is the second most common intensive care unit (ICU) medication error. The active partial thromboplastin time (aPTT) monitors heparin, but suffers from long turnaround times, a variable reference range, limited utility with low molecular weight heparin, and poor correlation to dose. Here, we describe a photoacoustic imaging technique to monitor heparin concentration using methylene blue as a s...

RNAi screening of the Glucose Regulated Chaperones in Cancer with Self-Assembled siRNA Nanostructures.

The emerging field of RNA nanotechnology has been used to design well-programmed, self-assembled nanostructures for applications in chemistry, biology and medicine. At the forefront of its utility in cancer is the unrestricted ability to self-assemble multiple siRNAs within a single nanostructure formulation for the RNAi screening of a wide range of oncogenes while potentiating the gene therapy of malignant tumors. In our RNAi nanotechnology approach, V- and Y-shape RNA templates were designed and construct...

Absorption Spectroscopy of an Individual Fano Cluster.

Plasmonic clusters can exhibit Fano resonances with unique and tunable asymmetric lineshapes, which arise due to the coupling of bright and dark plasmon modes within each multi-particle structure. These structures are capable of generating remarkably large local electromagnetic field enhancements, and should give rise to high hot carrier yields relative to other plasmonic nanostructures. While the scattering properties of individual plasmonic Fano resonances have been characterized extensively both experime...

Plasmonic Crystals for Strong Light-Matter Coupling in Carbon Nanotubes.

Their high oscillator strength and large exciton binding energies make single-walled carbon nanotubes (SWCNTs) highly promising materials for the investigation of strong-light matter interactions in the near-infrared and at room temperature. To explore their full potential, high-quality cavities - possibly with nanoscale field localization - are required. Here, we demonstrate the room temperature formation of plasmon-exciton polaritons in monochiral (6,5) SWCNTs coupled to the sub-diffraction nanocavities o...

Nanodomain Engineering in Ferroelectric Capacitors with Graphene Electrodes.

Polarization switching in ferroelectric capacitors is typically realized by application of an electrical bias to the capacitor electrodes and occurs via a complex process of domain structure reorganization. As the domain evolution in real devices is governed by the distribution of the nucleation centers, obtaining a domain structure of a desired configuration by electrical pulsing is challenging, if not impossible. Recent discovery of polarization reversal via the flexoelectric effect has opened a possibili...

Atomic Migration Induced Crystal Structure Transformation and Core-Centered Phase Transition in Single Crystal Ge2Sb2Te5 Nanowires.

A phase change nanowire holds a promise for nonvolatile memory applications, but its transition mechanism has remained unclear due to the analytical difficulties at atomic resolution. Here we obtain a deeper understanding on the phase transition of a single crystalline Ge2Sb2Te5 nanowire (GST NW) using atomic scale imaging, diffraction, and chemical analysis. Our cross-sectional analysis has shown that the as-grown hexagonal close-packed (HCP) structure of the single crystal GST NW transforms to a metastabl...

Photo-detection and Photoswitch based on Polarized Optical Response of Macroscopically Aligned Carbon Nanotubes.

Light polarization is extensively applied in optical detection, industry processing and tele communication. Although aligned carbon nanotube naturally suppresses the transmittance of light polarized parallel to its axial direction, there is little application regarding the photodetection of carbon nanotube based on this anisotropic interaction with linearly polarized light. Here, we report a photo-detection device realized by aligned carbon nanotube. Due to the different absorption behavior of polarized lig...

Polar Second-Harmonic Imaging to Resolve Pure and Mixed Crystal Phases Along GaAs Nanowires.

In this work, we report an optical method to characterize crystal phases along single semiconductor III-V nanowires, based on the measurement of polarization-dependent second-harmonic generation. This powerful imaging method is based on a per-pixel analysis of the second-harmonic generated signal on the incoming excitation polarization. The dependence of the second-harmonic generation responses on the nonlinear second-order susceptibility tensor allows to distinguish areas of pure wurtzite, zinc blende, mix...

Spatio-Temporal Imaging of the Acoustic Field Emitted by a Single Copper Nanowire.

The monochromatic and geometrically anisotropic acoustic field generated by 400 nm and 120 nm diameter copper nanowires simply dropped on a 10 µm silicon membrane is investigated in transmission using three-dimensional time-resolved femtosecond pump-probe experiments. Two pump-probe time-resolved experiments are carried out at the same time on both side of the silicon substrate. In reflection, the first radial breathing mode of the nanowire is excited and detected. In transmission, the longitudinal and she...

Substrate-Induced Nanoscale Undulations of Borophene on Silver.

Two-dimensional (2D) materials tend to be mechanically flexible yet planar, especially when adhered on metal substrates. Here, we show by first-principles calculations that periodic nanoscale one-dimensional undulations can be preferred in borophenes on concertedly reconstructed Ag(111). This "wavy" configuration is more stable than its planar form on flat Ag(111) due to anisotropic high bending flexibility of borophene that is also well described by a continuum model. Atomic-scale ultra-high vacuum scannin...

Direct intertube crosslinking of carbon nanotubes at room temperature.

Carbon nanotubes (CNTs) have long been regarded as efficient free radical scavenger because of the large-conjugation system in their electronic structures. Hence, in spite of abundant reports on CNT reacting with incoming free radical species, current research has not seen CNT itself displaying the chemical reactivity of free radicals. Here we show that reactive free radicals can in fact be generated on carbon nanotubes via reductive defluorination of highly fluorinated single-walled carbon nanotubes (FSWNT...

Two Dimensional Antiferromagnetic Chern Insulator: NiRuCl6.

Density functional theory (DFT) and Berry curvature calculations show that quantum anomalous Hall effect (QAHE) can be realized in two-dimensional anti-ferromagnetic (AFM) NiRuCl6. The results indicate that NiRuCl6 behaves as an AFM Chern insulator and its spin-polarized electronic structure and strong spin-orbits coupling (SOC) are responsible for the QAHE. By tuning SOC, we found that the topological property of NiRuCl6 arises from its energy band reversal. Considering the compatibility between the AFM an...

Blue Phosphorene Oxide: Strain-tunable Quantum Phase Transitions and Novel 2D Emergent Fermions.

Tunable quantum phase transitions and novel emergent fermions in solid state materials are fascinating subjects of research. Here, we propose a new stable two-dimensional (2D) material, the blue phosphorene oxide (BPO), which exhibits both. Based on first-principles calculations, we show that its equilibrium state is a narrow-bandgap semiconductor with three bands at low energy. Remarkably, a moderate strain can drive a semiconductor-to-semimetal quantum phase transition in BPO. At the critical transition p...

Light-induced Polarization-directed Growth of Optically Printed Gold Nanoparticles.

Optical printing has been proved a versatile and simple method to fabricate arbitrary arrays of colloidal nanoparticles (NPs) on substrates. Here we show that is also a powerful tool for studying chemical reactions at the single NP level. We demonstrate that 60 nm gold NPs immobilized by optical printing can be used as seeds to obtain larger NPs by plasmon-assisted reduction of aqueous HAuCl4. The final size of each NP is simply controlled by the irradiation time. Moreover, we show conditions for which the ...

Fano interference in the optical absorption of an individual gold-silver nanodimer.

Fano resonances are central features in the responses of many systems including atoms, molecules, and nanomaterials. They are consequences of interferences between two channels, most frequently associated to two system modes. In plasmonic materials, Fano interferences between optical modes have been shown, experimentally and theoretically, to induce narrow features in their scattering spectra. By investigating individual silver-gold heterodimers, we first experimentally demonstrate that Fano interference is...

Auxetic Black Phosphorus: A 2D Material with Negative Poisson's Ratio.

The Poisson's ratio of a material characterizes its response to uniaxial strain. Materials normally possess a positive Poisson's ratio - they contract laterally when stretched, and expand laterally when compressed. A negative Poisson's ratio is theoretically permissible but has not, with few exceptions of man-made bulk structures, been experimentally observed in any natural materials. Here, we show that the negative Poisson's ratio exists in the low-dimensional natural material black phosphorus, and that ou...

Electron excess doping and effective Schottky barrier reduction on MoS2/h-BN heterostructure.

Layered hexagonal boron nitride (h-BN) thin film is a dielectric that surpasses carrier mobility by reducing charge scattering with silicon oxide in diverse electronics formed with graphene and transition metal dichalcogenides. However, the h-BN effect on electron doping concentration and Schottky barrier is little known. Here, we report that use of h-BN thin film as a substrate for monolayer MoS2 can induce ~6.5 × 10(11) cm(-2) electron doping at room temperature which was determined using theoretical fla...

Long-Circulating Au-TiO2 Nanocomposite as a Sonosensitizer for ROS-Mediated Eradication of Cancer.

Although sonodynamic therapy (SDT) has emerged as a potential alternative to conventional photodynamic therapy, the low quantum yield of the sonosensitizer such as TiO2 nanoparticles (NPs) is still a major concern. Here, we have developed hydrophilized Au-TiO2 nanocomposites (HAu-TiO2 NCs) as sonosensitizers for improved SDT. The physicochemical properties of HAu-TiO2 NCs were thoroughly studied and compared with their counterparts without gold deposition. Upon exposure of HAu-TiO2 NCs to ultrasound, a larg...

Ultrasensitive pH Triggered Charge/Size Dual-Rebound Gene Delivery System.

A facile strategy is developed to construct an ultrasensitive pH triggered charge/size dual-rebound gene delivery system for efficient tumor treatment. Therapeutic gene is complexed by polyethylenimine (PEI) and poly-L-glutamate (PLG), further in situ tightened by aldehyde modified polyethylene glycol (PEG) via Schiff base reaction. The generated Schiff base bonds are stable in neutral pH but cleavable in tumor extracellular pH. This gene delivery system possesses following favorable properties: (1) the tun...


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