Controlling the reproducibility of Coulomb blockade phenomena for gold nanoparticles on an organic monolayer/silicon system

Two types of highly ordered organic layers were prepared on silicon modified with an amine termination for binding gold nanoparticles (AuNPs). These two grafted organic monolayers (GOMs), consisting of alkyl chains with seven or 11 carbon atoms, were grafted on oxide-free Si(111) surfaces as tunnel barriers between the silicon electrode and the AuNPs. Three kinds of colloidal AuNPs were prepared by reducing HAuCl 4 with three different reactants: citrate (Turkevich synthesis, diameter ∼16 nm), ascorbic acid (diameter ∼9 nm), or NaBH 4 (Natan synthesis, diameter ∼7 nm). Scanning tunnel spectroscopy (STS) was performed in a UHV STM at 40 K, and Coulomb blockade behaviour was observed. The reproducibility of the Coulomb behavior was analysed as a function of several chemical and physical parameters: size, crystallinity of the AuNPs, influence of surrounding surfactant molecules, and quality of the GOM/Si interface (degree of oxidation after the full processing). ...

L Caillard, S Sattayaporn, A-F Lamic-Humblot, S Casale, P Campbell, Y J Chabal and O Pluchery

Click for full article

DNA motion induced by electrokinetic flow near an Au coated nanopore surface as voltage controlled gate

We used fluorescence microscopy to investigate the diffusion and drift motion of λ DNA molecules on an Au-coated membrane surface near nanopores, prior to their translocation through solid-state nanopores. With the capability of controlling electric potential at the Au surface as a gate voltage, V gate , the motions of DNA molecules, which are presumably generated by electrokinetic flow, vary dramatically near the nanopores in our observations. We carefully investigate these DNA motions with different values of V gate in order to alter the densities and polarities of the counterions, which are expected to change the flow speed or direction, respectively. Depending on V gate , our observations have revealed the critical distance from a nanopore for DNA molecules to be attracted or repelled—DNA’s anisotropic and unsteady drifting motions and accumulations of DNA molecules near the nanopore entrance. Further finite element method (FEM) numerical si...

Manabu Sugimoto, Yuta Kato, Kentaro Ishida, Changbae Hyun, Jiali Li and Toshiyuki Mitsui

Click for full article

Unusual ferromagnetism in CoSi nanowires from internal and interfacial defects

The diamagnetic semimetal CoSi presents unanticipated ferromagnetism as CoSi/SiO 2 nanowires (NWs). Using first-principles calculations, we offer physical insights into the origins of this unusual magnetism. Due to the distorted and dangling bonds near the NW surface with different bond lengths, the transition metal (Co) d-orbital electron spin up and spin down populations become asymmetric from the exchange interactions, providing the mechanism for some of the measured magnetization. However, the distorted and dangling bonds are clearly not the only factor contributing to the magnetization of the NWs. The transmission electron microscopy selected area electron diffraction analysis of the CoSi region suggested a superlattice structure existed in the cubic CoSi, and defects existing as ordered vacancies in the CoSi were present. The simulation’s results for the Co moment in the CoSi NWs without these ordered vacancies, but incorporating the surface and internal spin mome...



Click for full article

Freestanding polyaniline nanorods grown on graphene for highly capacitive energy storage

Freestanding polyaniline (PANI) nanorods grown in situ on microwave-expanded graphene oxide (MEGO) sheets were prepared through a facile solution method. The morphological characterization indicates that large quantity of free-standing PANI nanorods with average diameter of 50 nm were uniformly deposited onto the double sides of the MEGO nanosheets to form a sandwich structure. The hybrid of PANI/MEGO (GPANI) exhibit high specific surface area and high electrical conductivity, compared with pristine PANI nanorods. When evaluated as electrodes for supercapacitors, the GPANI demonstrate high specific capacitance of 628 F g −1 at a current density of 1.1 A g −1 , high-rate performance, and excellent cycle stability compared to individual component. Such excellent electrochemical performance should be attributed to the combined double-layer capacitance and pseudo -capacitance mechanisms from the MEGO sheets and PANI nanorods.

Zijiong Li, Zhen Qin, Baocheng Yang, Jian Guo, Haiyan Wang, Weiyang Zhang, Xiaowei Lv and Alison Stack

Click for full article

Micropatterned nanostructures: a bioengineered approach to mass-produce functional myocardial grafts

Cell-based therapies are a recently established path for treating a wide range of human disease. Tissue engineering of contractile heart muscle for replacement therapy is among the most exciting and important of these efforts. However, current in vitro techniques of cultivating functional mature cardiac grafts have only been moderately successful due to the poor capability of traditional two-dimensional cell culture systems to recapitulate necessary in vivo conditions. In this issue, Kiefer et al [1] introduce a laser-patterned nanostructured substrate (Al/Al 2 O 3 nanowires) for efficient maintenance of oriented human cardiomyocytes, with great potential to open new roads to mass-production of contractile myocardial grafts for cardiovascular tissue engineering.



Click for full article

Reduced graphene oxide supported platinum nanocubes composites: one-pot hydrothermal synthesis and enhanced catalytic activity

Reduced graphene oxide (rGO) supported platinum nanocubes (Pt-NCs) composites (Pt-NCs/rGO) were synthesized successfully by a water-based co-chemical reduction method, in which polyallylamine hydrochloride acted as a multi-functional molecule for the functionalization of graphene oxide, anchorage of Pt II precursor, and control of Pt crystal facets. The morphology, structure, composition, and catalytic property of Pt-NCs/rGO composites were characterized in detail by various spectroscopic techniques. Transmission electron microscopy images showed well-defined Pt-NCs with an average size of 9 nm uniformly distributed on the rGO surface. The as-prepared Pt-NCs/rGO composites had excellent colloidal stability in the aqueous solution, and exhibited superior catalytic activity towards the hydrogenation reduction of nitro groups compared to commercial Pt black. The improved catalytic activity originated from the abundant exposed Pt{100} facets of Pt-NCs, excellent dispersion ...

Fumin Li, Xueqing Gao, Qi Xue, Shuni Li, Yu Chen and Jong-Min Lee

Click for full article

Titanium nanostructures for biomedical applications

Titanium and titanium alloys exhibit a unique combination of strength and biocompatibility, which enables their use in medical applications and accounts for their extensive use as implant materials in the last 50 years. Currently, a large amount of research is being carried out in order to determine the optimal surface topography for use in bioapplications, and thus the emphasis is on nanotechnology for biomedical applications. It was recently shown that titanium implants with rough surface topography and free energy increase osteoblast adhesion, maturation and subsequent bone formation. Furthermore, the adhesion of different cell lines to the surface of titanium implants is influenced by the surface characteristics of titanium; namely topography, charge distribution and chemistry. The present review article focuses on the specific nanotopography of titanium, i.e. titanium dioxide (TiO 2 ) nanotubes, using a simple electrochemical anodisation method of the metallic subst...

M Kulkarni, A Mazare, E Gongadze, ? Perutkova, V Kralj-Igli?, I Milo?ev, P Schmuki, A Igli? and M Mozeti?

Click for full article

A simple strategy for synthesizing highly luminescent carbon nanodots and application as effective down-shifting layers

We propose a novel strategy to prepare highly luminescent carbon nanodots (C-dots) by employing a hydrothermal method with citric acid as the carbon source and ethylenediamine as the nitrogen source, together with adding moderate ammonia water (AW) to achieve both appropriate inner structure and excellent N passivation. The effect of pH value and AW amount on the luminescence properties has been thoroughly investigated. The photoluminescence quantum yield of the resultant C-dots reaches as high as 84.8%, which is of 10.56% higher than that of the C-dots synthesized in the absence of AW in the reaction precursors. We have further combined the highest luminescent C-dots with polyvinyl alcohol to form luminescent down-shifting layers on silicon nanowire solar cells. An effective enhancement of short-circuit current density has been realized and the contribution of the down-shifting has been extracted quantitatively from the deterioration of surface reflectance and the gain of the op...

Xugen Han, Sihua Zhong, Wei Pan and Wenzhong Shen

Click for full article

Semiconductor to metal transition in bilayer phosphorene under normal compressive strain

Phosphorene, a two-dimensional analog of black phosphorous, has been a subject of immense interest recently, due to its high carrier mobilities and a tunable bandgap. So far, tunability has been predicted to be obtained with very high compressive/tensile in-plane strains, and vertical electric field, which are difficult to achieve experimentally. Here, we show using density functional theory based calculations the possibility of tuning electronic properties by applying normal compressive strain in bilayer phosphorene. A complete and fully reversible semiconductor to metal transition has been observed at ##IMG## [http://ift.tt/15dTGeF] {$\sim 13.35\%$} strain, which can be easily realized experimentally. Furthermore, a direct to indirect bandgap transition has also been observed at ##IMG## [http://ift.tt/1BJQJAL] {$\sim 3\%$} strain, which is a sign...

Aaditya Manjanath, Atanu Samanta, Tribhuwan Pandey and Abhishek K Singh

Click for full article

Synthesis and characterization of FeCo nanowires with high coercivity

Ferromagnetic FeCo nanocrystals with high coercivity have been synthesized using a reductive decomposition method. The sizes and shapes of the nanocrystals were found to be dependent on reaction parameters such as the surfactant ratio, the precursor concentration and the heating rate. Synthesized nanocrystals have a body-centered cubic crystal structure for both particles and nanowires and the (110) crystalline direction is along the long axis of the nanowires. The coercivity and magnetization of the FeCo nanocrystals are found to be dependent on morphology. Nanowires of Fe 60 Co 40 with saturation magnetization of 92 emu g −1 and coercive force of 1.2 kOe have been obtained in this study.



Click for full article

Efficient Bifunctional Fe/C/N Electrocatalysts for Oxygen Reduction and Evolution Reaction

The Journal of Physical Chemistry C

DOI: 10.1021/jp511515q

Yong Zhao, Kazuhide Kamiya, Kazuhito Hashimoto and Shuji Nakanishi

Click for full article

Laser Desorption Mass Spectrometry of End Group-Protected Linear Polyynes: Evidence of Laser-Induced Cross-Linking

The Journal of Physical Chemistry C

DOI: 10.1021/jp5112444

Rolf W. Kirschbaum, Dominik Prenzel, Stephanie Frankenberger, Rik R. Tykwinski and Thomas Drewello

Click for full article

High-Performance Microsupercapacitors Based on Two-Dimensional Graphene/Manganese Dioxide/Silver Nanowire Ternary Hybrid Film

ACS Nano

DOI: 10.1021/nn5060442

Wenwen Liu, Congxiang Lu, Xingli Wang, Roland Yingjie Tay and Beng Kang Tay

Click for full article

Engineering Poly(ethylene glycol) Particles for Improved Biodistribution

ACS Nano

DOI: 10.1021/nn5061578

Jiwei Cui, Robert De Rose, Karen Alt, Sheilajen Alcantara, Brett M. Paterson, Kang Liang, Ming Hu, Joseph J. Richardson, Yan Yan, Charmaine M. Jeffery, Roger I. Price, Karlheinz Peter, Christoph E. Hagemeyer, Paul S. Donnelly, Stephen J. Kent and Frank Caruso

Click for full article

Nanotubular J-Aggregates and Quantum Dots Coupled for Efficient Resonance Excitation Energy Transfer

ACS Nano

DOI: 10.1021/nn506095g

Yan Qiao, Frank Polzer, Holm Kirmse, Egon Steeg, Sergei Kühn, Sebastian Friede, Stefan Kirstein and Jürgen P. Rabe

Click for full article

Coincident Site Epitaxy at the Junction of Au–Cu2ZnSnS4 Heteronanostructures

Chemistry of Materials

DOI: 10.1021/cm504434q

Biplab K Patra, Arnab Shit, Amit K Guria, Suresh Sarkar, Gyanaranjan Prusty and Narayan Pradhan

Click for full article

Doping Controls Plasmonics, Electrical Conductivity, and Carrier-Mediated Magnetic Coupling in Fe and Sn Codoped In2O3 Nanocrystals: Local Structure Is the Key

Chemistry of Materials

DOI: 10.1021/cm5040936

G. Shiva Shanker, Bharat Tandon, Tomohiro Shibata, Soma Chattopadhyay and Angshuman Nag

Click for full article

Effect of Hydrate Shell Formation on the Stability of Dry Water

The Journal of Physical Chemistry C

DOI: 10.1021/jp510603q

Juwoon Park, Kyuchul Shin, Jakyung Kim, Huen Lee, Yutaek Seo, Nobuo Maeda, Wendy Tian and Colin D. Wood

Click for full article

Segregation of In to Dislocations in InGaN

Nano Letters

DOI: 10.1021/nl5036513

Matthew K. Horton, Sneha Rhode, Suman-Lata Sahonta, Menno J. Kappers, Sarah J. Haigh, Timothy J. Pennycook, Colin J. Humphreys, Rajiv O. Dusane and Michelle A. Moram

Click for full article

Electropolymerization: Further Insight into the Formation of Conducting Polyindole Thin Films

The Journal of Physical Chemistry C

DOI: 10.1021/jp512208s

Balázs B. Berkes, Aliaksandr S. Bandarenka and György Inzelt

Click for full article