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PubMed Journal Database | Nano letters RSS

15:51 EDT 26th July 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 3,000+ from Nano letters

Vertical Single-Crystalline Organic Nanowires on Graphene: Solution-Phase Epitaxy and Optical Microcavities.

Vertically aligned nanowires (NWs) of single crystal semiconductors have attracted a great deal of interest in the past few years. They have strong potential to be used in device structures with high density and with intriguing optoelectronic properties. However, fabricating such nanowire structures using organic semiconducting materials remains technically challenging. Here we report a simple procedure for the synthesis of crystalline 9,10-bis(phenylethynyl) anthracene (BPEA) NWs on a graphene surface util...

Diffusion-Mediated Synthesis of MoS2/WS2 Lateral Heterostructures.

Controlled growth of two-dimensional transition metal dichalcogenide (TMD) lateral heterostructures would enable on-demand tuning of electronic and optoelectronic properties in this new class of materials. Prior to this work, compositional modulations in lateral TMD heterostructures have been considered to depend solely on the growth chronology. We show that in-plane diffusion can play a significant role in the chemical vapor deposition of MoS2/WS2 lateral heterostructures leading to a variety of non-trivia...

Terahertz Spectroscopy of Individual Single-Walled Carbon Nanotubes as a Probe of Luttinger Liquid Physics.

Luttinger liquid theory predicts that collective electron excitations due to strong electron-electron interactions in a one-dimensional (1D) system will result in a modification of the collective charge-propagation velocity. By utilizing a circuit model for an individual metallic single-walled carbon nanotube as a nanotransmission line, it has been shown that the frequency-dependent terahertz impedance of a carbon nanotube can probe this expected 1D Luttinger liquid behavior. We excite terahertz standing-wa...

The interplay of symmetry and scattering phase in second harmonic generation from gold nano-antennas.

Nonlinear phenomena are central to modern photonics but, being inherently weak, typically require gradually accumulation over several millimetres. For example, second harmonic generation (SHG) is typically achieved in thick transparent nonlinear crystals by phase-matching energy exchange between light at initial, ω, and final, 2ω, frequencies. Recently, metamaterials imbued with artificial nonlinearity from their constituent nano-antennas have generated excitement by opening the possibility of wavelength-...

A Tuneable Magnetic Domain Wall Conduit Regulating Nanoparticle Diffusion.

We demonstrate a general and robust method to confine on a plane strongly diffusing nanoparticles in water by using size tunable magnetic channels. These virtual conduits are realized with pairs of movable Bloch walls (BWs) located within an epitaxially grown ferrite garnet film. We show that, once inside the magnetic conduit, nanoparticles experience an effective local parabolic potential in the transverse direction, while freely diffusing along the conduit. The stiffness of the magnetic potential is deter...

On-chip clonal analysis of glioma stem cell motility and therapy resistance.

Enhanced glioma stem cell (GSC) motility and therapy resistance are considered to play key roles in tumor cell dissemination and life-threatening recurrence. As such, a better understanding of the mechanisms by which these cells disseminate and withstand therapy could lead to more efficacious treatments for this devastating disease. Here we introduce a novel micro/nanotechnology-based chip platform for performing live-cell interrogation of patient-derived GSC cultures with single-clone resolution. On-chip a...

BROADBAND ENHANCEMENT OF SPONTANEOUS EMISSION IN 2D SEMICONDUCTORS USING PHOTONIC HYPERCRYSTALS.

The low quantum yield observed in two-dimensional semiconductors of transition metal dichalcogenides (TMDs) has motivated the quest for approaches that can enhance the light emission from these systems. Here, we demonstrate broadband enhancement of spontaneous emission and increase in Raman signature from archetype two-dimensional semiconductors: molybdenum disulfide (MoS2) and tungsten disulfide (WS2) by placing the monolayers in the near field of a photonic hypercrystal (PHC) having hyperbolic dispersion....

Tailoring Vacancies Far Beyond Intrinsic Levels Changes the Carrier Type in Monolayer MoSe2-x Crystals.

Defect engineering has been a critical step in controlling the transport characteristics of electronic devices, and ability to create, tune, and annihilate defects is essential to enable the range of next-generation devices. Whereas defect formation has been well demonstrated in three-dimensional semiconductors, similar exploration of the heterogeneity in atomically-thin two-dimensional semiconductors and the link between their atomic structures, defects, and properties has not yet been extensively studied....

Effects of Electrode Layer Band Structure on the Performance of Multi-Layer Graphene-hBN-Graphene Interlayer Tunnel Field Effect Transistors.

Interlayer tunnel field-effect transistors based on graphene and hexagonal boron nitride (hBN) have recently attracted much interest for their potential as beyond-CMOS devices. Using a recently developed method for fabricating rotationally aligned two-dimensional heterostructures, we show experimental results for devices with varying thicknesses and stacking order of the graphene electrode layers, and also model the current-voltage behavior. We show that an increase in the graphene layer thickness results i...

Building Diatomic and Triatomic Superatom Molecules.

In this study, we have developed a method to create Co6Se8 superatoms in which we program the metal-ligand bonds. We exclusively form the Co6Se8 core under simple reaction conditions with a facile separation of products that contain differential substitution of the core. The combination of Co2(CO)8 and PR3 with excess Se gives the differentially and directionally substituted superatoms, Co6Se8(CO)x(PR3)(6-x). The CO groups on the superatom can be exchanged quantitatively with phosphines and isonitriles. Sub...

Mechanisms of local stress sensing in multifunctional polymer films using fluorescent tetrapod nanocrystals.

Nanoscale stress-sensing can be used across fields ranging from detection of incipient cracks in structural mechanics to monitoring forces in biological tissues. We demonstrate how tetrapod quantum dots (tQDs) embedded in block-copolymers act as sensors of tensile/compressive stress. Remarkably, tQDs can detect their own composite dispersion and mechanical properties, with a switch in optomechanical response when tQDs are in direct contact. Using experimental characterizations, atomistic simulations and fin...

Synthesis of group IV nanowires on graphene - the case of Ge nanocrawlers.

In recent years, there has been a growing interest in using graphene as a synthesis platform for polymers, zero-dimensional (0D) materials, one-dimensional materials (1D), and two-dimensional (2D) materials. Here, we report the investigation of the growth of germanium nanowires (GeNWs) and germanium nanocrawlers (GeNCs) on single-layer graphene surfaces. GeNWs and GeNCs are synthesized on graphene films by gold nanoparticles catalyzed vapor-liquid-solid growth mechanism. The addition of hydrogen chloride ga...

Transformation optics: a time- and frequency-domain analysis of electron-energy loss spectroscopy.

Electron energy loss spectroscopy (EELS) and Cathodoluminescence (CL) play a pivotal role in many of the cutting edge experiments in plasmonics. EELS and CL experiments are usually supported by numerical simulations, which, whilst accurate, may not provide as much physical insight as analytical calculations do. Fully analytical solutions to EELS and CL systems in plasmonics are rare and difficult to obtain. This paper aims to narrow this gap by introducing a new method based on Transformation optics that al...

Electrochemically formed ultrafine metal oxide nano-catalysts for high-performance lithium-oxygen batteries.

Lithium-oxygen (Li-O2) batteries have an extremely high theoretical specific energy density when compared with conventional energy-storage systems. However, practical application of the Li-O2 battery system still faces significant challenges. In this work, we report a new approach for synthesis of ultrafine metal oxide nano-catalysts through an electrochemical pre-lithiation process. This process reduces the size of NiCo2O4 (NCO) particles from 20~30 nm to a uniformly distributed domain of ~2 nm and signifi...

Active nanorheology with plasmonics.

Nanoplasmonic systems are valued for their strong optical response and their small size. Most plasmonic sensors and systems to date have been rigid and passive. However, rendering these structures dynamic opens new possibilities for applications. Here we demonstrate that dynamic plasmonic nanoparticles can be used as mechanical sensors to selectively probe the rheological properties of a fluid in situ at the nanoscale and in microscopic volumes. We fabricate chiral magneto-plasmonic nanocolloids that can be...

THz conductivity within colloidal CsPbBr3 perovskite nanocrystals: remarkably high carrier mobilities and large diffusion lengths.

Colloidal CsPbBr3 perovskite nanocrystals (NCs) have emerged as an excellent light emitting material in last one year. Using time domain and time-resolved THz spectroscopy and density functional theory based calculations, we establish three fold free carrier recombination mechanism, namely, non-radiative Auger, bi-molecular electron-hole recombination and inefficient trap-assisted recombination in 11 nm sized colloidal CsPbBr3 NCs. Our results confirm a negligible influence of surface defects in trapping ch...

Controlling the Reversible Assembly of Liposomes through a Multistimuli Responsive Anchored DNA.

We present a novel approach to reversibly control the assembly of liposomes through an anchored multistimuli responsive DNA oligonucleotide decorated with an azobenzene moiety (AZO-ON1). We show that liposomes assembly can be simultaneously controlled by three external stimuli: light, Mg(2+), and temperature. (i) Light alters the interaction of AZO-ON1 with liposomes, which influences DNA coating and consequently liposomes assembly. (ii) Mg(2+) induces the assembly, hence variation in its concentration enab...

Graphene-templated supported lipid bilayer nanochannels.

The use of patterned substrates to impose geometrical restriction on the lateral mobility of molecules in supported lipid membranes has found widespread utility in studies of cell membranes. Here, we template-pattern supported lipid membranes with nano-patterned graphene. We utilize focused ion beam milling to pattern graphene on its growth substrate, then transfer the patterned graphene to fresh glass substrates for subsequent supported membrane formation. We observe that graphene functions as an excellent...

Metal-semiconductor nanoparticle hybrids formed by self-organization: a platform to address exciton-plasmon coupling.

Hybrid nanosystems composed of excitonic and plasmonic constituents can have different properties than the sum of both, due to the exciton-plasmon interaction. To promote understanding of such hybrid systems, connected experiments and universal theoretical descriptions are desired. Here, we report on a flexible model system based on colloidal nanoparticles that can form hybrid combinations by self-organization. The system allows to tune the interparticle distance and to combine nanoparticles of different si...

Intercalation-based single-molecule fluorescence assay to study DNA supercoil dynamics.

DNA supercoiling crucially affects cellular processes such as DNA replication, gene expression, and chromatin organization. However, mechanistic understanding of DNA supercoiling and the related DNA-processing enzymes has remained limited, mainly due to the lack of convenient experimental tools to probe these phenomena. Here, we report a novel high-throughput single-molecule assay for real-time visualization of supercoiled DNA molecules, named ISD (Intercalation-induced Supercoiling of DNA). We use an inter...

Conformational Changes and Flexibility of DNA Devices Observed by Small-Angle X-Ray Scattering.

Self-assembled DNA origami nanostructures enable the creation of precisely defined shapes at the molecular scale. Dynamic DNA devices that are capable of switching between defined conformations could afford completely novel functionalities for diagnostic, therapeutic, or engineering applications. Developing such objects benefits strongly from experimental feedback about conformational changes and 3D structures, ideally in solution, free of potential biases from surface attachment or labeling. Here we demons...

Doping-Induced Tunable Wettability and Adhesion of Graphene.

We report that substrate doping-induced charge carrier density modulation leads to the tunable wettability and adhesion of graphene. Graphene's water contact angle changes by as much as 13˚ as a result of a 300-meV change in doping level. Upon either n- or p-type doping with subsurface polyelectrolytes, graphene exhibits increased hydrophilicity. Adhesion force measurements using a hydrophobic self-assembled monolayer-coated atomic force microscopy probe reveal enhanced attraction toward undoped graphene, ...

High Cycle Fatigue in the Transmission Electron Microscope.

One of the most common causes of structural failure in metals is fatigue induced by cyclic loading. Historically, microstructure-level analysis of fatigue cracks has primarily been performed post mortem. However, such investigations do not directly reveal the internal structural processes at work near micro- and nanoscale fatigue cracks, and thus do not provide direct evidence of active microstructural mechanisms. In this study the tension-tension fatigue behavior of nanocrystalline Cu was monitored in real...

Direct Optical Visualization of Graphene and Its Nanoscale Defects on Transparent Substrates.

The discovery and rise of graphene were historically enabled by its ∼10% optical contrast on specialized substrates like oxide-capped silicon. However, substantially lower contrast is obtained on transparent substrates. Moreover, it remains difficult to visualize nanoscale defects in graphene, including voids, cracks, wrinkles, and multilayers, on most device substrates. We report the use of interference reflection microscopy (IRM), a facile, label-free optical microscopy method originated in cell biology...

Nanotwin Detection and Domain Polarity Determination via optical second harmonic generation polarimetry.

We demonstrate that optical second harmonic generation (SHG) can be utilized to determine the exact nature of nanotwins in noncentrosymmetric crystals, which is challenging to resolve via conventional transmission electron or scanned probe microscopies. Using single-crystalline nanotwinned CdTe nanobelts and nanowires as a model system, we show that SHG polarimetry can distinguish between upright (Cd-Te bonds) and inverted (Cd-Cd or Te-Te bonds) twin boundaries in the system. Inverted twin boundaries are ge...


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