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Hisashi Sugime, Lorenzo D'Arsié, Santiago Esconjauregui, Guofang Zhong, Xingyi Wu, Eugen Hildebrandt, Hikmet Sezen, Matteo Amati, Luca Gregoratti, Robert S Weatherup, John Robertson
A bimetallic CoCu alloy thin-film catalyst is developed that enables the growth of uniform, high-quality graphene at 750 °C in 3 min by chemical vapour deposition. The growth outcome is found to vary significantly as the Cu concentration is varied, with ∼1 at% Cu added to Co yielding complete coverage single-layer graphene growth for the conditions used. The suppression of multilayer formation is attributable to Cu decoration of high reactivity sites on the Co surface which otherwise serve as preferential nucleation sites for multilayer graphene...
September 19, 2017: Nanoscale
Writam Banerjee, Qi Liu, Hangbing Lv, Shibing Long, Ming Liu
Seeking an effective electronic synapse to emulate biological synaptic behavior is fundamental for building brain-inspired computers. An emerging two-terminal memristor, in which the conductance can be gradually modulated by external electrical stimuli, is widely considered as the strongest competitor of the electronic synapse. Here, we show the capability of TiOx/Al2O3-based memristor devices to imitate synaptic behaviors. Along with analog resistive switching performances, the devices replicate the bio-synapse behaviors of potentiation/depression, short-term-plasticity, and long-term-potentiation, which show that TiOx/Al2O3-based memristors may be useful as electronic synapses...
September 19, 2017: Nanoscale
Krishna P Acharya, Alexandre Titov, Jake Hyvonen, Chenggong Wang, Jean Tokarz, Paul H Holloway
Colloidal quantum dot-polymer hybrid light emitting diodes (QLEDs) that exhibit external quantum efficiencies >12% for all three primary colors (21% from green) have been demonstrated. These high efficiencies result in part from a positive aging effect reported here for the first time, where positive aging means the efficiency of the QLED increased with time. We have achieved 470 h operational life time (T90) at 2550 nits for red QLEDs. At longer times, negative aging phenomena lead to lower luminance and limit the lifetime of the QLEDs...
September 19, 2017: Nanoscale
Maria Koifman Khristosov, Shiri Dishon, Imrit Noi, Alex Katsman, Boaz Pokroy
Nanoporous gold is widely used in research and nanotechnology because of its diverse properties, including high surface area and catalytic activity. The ligament size is usually considered as one of the main parameters controlling thermal stability and mechanical properties of nanoporous gold. Recently we developed a method for creating nanoporous single crystal gold particles using eutectic decomposition of Au-Ge, followed by selective etching of Ge. Here, we used this novel method to create nanoporous gold particles with controlled ligament sizes by changing the initial sample's relative concentrations of gold and germanium...
September 19, 2017: Nanoscale
Zheguan Lin, Jinjin Lin, Lingting Huang, Xiaoyan Zhang, Ying Wang, Zizhong Zhang, Huaxiang Lin, Xuxu Wang
Developing a heterostructure on the surface of a "sandwich" structure semiconductor is essential for full utilization of its heterojunction function and hence for designing efficient solar energy conversion systems. Here, we show that 2D-2D MoS2/MnSb2S4 heterostructure composites are designed for the first time and successfully synthesized by a simple in situ calcination pathway. Under visible light irradiation, the ca. 3.3 wt% MoS2/MnSb2S4 samples exhibited the highest activity for H2 evolution, which was 7...
September 18, 2017: Nanoscale
Hongyu Sun, Yanyan Zhao, Kristian Mølhave, Minwei Zhang, Jingdong Zhang
We developed a facile solution reductive method to simultaneously tune the surface composition, oxygen vacancies and three dimensional assembly in Co3O4 hierarchical nanostructures. The controllable surface composition, oxygen vacancies together with hierarchical micro/nanoarchitectures resulted in superior electrochemical properties when used as the anode materials for lithium-ion batteries and as an electrocatalyst for the oxygen evolution reaction. The excellent electrochemical performance is attributed to the synergistic effects of novel hierarchical morphology, crystal structure of the active materials, the improvement of intrinsic conductivity and inner surface area induced by the oxygen vacancies...
September 18, 2017: Nanoscale
Kyu-Tae Lee, Ji-Yun Jang, Sang Jin Park, Song Ah Ok, Hui Joon Park
See-through perovskite solar cells with high efficiency and iridescent colors are demonstrated by employing a multilayer dielectric mirror. A certain amount of visible light is used for wide color gamut semitransparent color generation, which can be easily tuned by changing an angle of incidence, and a wide range of visible light is efficiently reflected back toward a photoactive layer of the perovskite solar cells by the dielectric mirror for highly efficient light-harvesting performance, thus achieving 10...
September 18, 2017: Nanoscale
Harshida Parmar, T Xiao, V Chaudhary, Y Zhong, R V Ramanujan
The excellent hard magnetic properties of Nd2Fe14B based magnets have an enormous range of technological applications. Exchange-coupled Nd2Fe14B/α-Fe magnets were chemically synthesized by a microwave assisted combustion process to produce mixed oxides, followed by a reduction diffusion process to form magnetic nano-composite powder. This synthesis technique offers an inexpensive and facile platform to produce exchange coupled hard magnets. The size dependent magnetic properties were investigated. The formation mechanisms of the oxide powders and the reduction diffusion mechanism were identified...
September 18, 2017: Nanoscale
Camilla La Torre, Andreas Kindsmüller, Dirk J Wouters, Catherine E Graves, Gary A Gibson, John Paul Strachan, R Stanley Williams, Rainer Waser, Stephan Menzel
Current-voltage characteristics of oxide-based resistive switching memories often show a pronounced asymmetry with respect to the voltage polarity in the high resistive state (HRS), where the HRS after the RESET is more conducting than the one before the SET. Here, we report that most of this HRS asymmetry is a volatile effect as the HRS obtained from a read operation differs from the one taken from the switching cycle at identical polarity and voltages. Transitions between the relaxed and the volatile excited states can be achieved via voltage sweeps, which are named subloops...
September 18, 2017: Nanoscale
Dennis Wang, Kori Smyser, Daniel Rhodes, Luis Balicas, Abhay Pasupathy, Irving P Herman
Several-layer 1T'-MoTe2 decomposes very little during heating up to ∼550 °C under flowing argon when encapsulated by multilayer hBN, as monitored by Raman scattering and optical microscopy, but largely decomposes at much lower temperatures in incompletely covered and uncovered regions. In covered regions there are small amounts of tellurium product above ∼250 °C.
September 18, 2017: Nanoscale
Sunmog Yeo, Hyunkyung Choi, Chul Sung Kim, Gyeong Tae Lee, Jeong Hyun Seo, Hyung Joon Cha, Jeong Chan Park
We have demonstrated that the Verwey transition, which is highly sensitive to impurities, survives in anisotropic Gd-doped magnetite nanoparticles. Transmission electron microscopy analysis shows that the nanoparticles are uniformly distributed. X-ray photoelectron spectroscopy and EDS mapping analysis confirm Gd-doping on the nanoparticles. The Verwey transition of the Gd-doped magnetite nanoparticles is robust and the temperature dependence of the magnetic moment (zero field cooling and field cooling) shows the same behaviour as that of the Verwey transition in bulk magnetite, at a lower transition temperature (∼110 K)...
September 18, 2017: Nanoscale
Chong Liu, Wenzhe Li, Hongliang Li, Cuiling Zhang, Jiandong Fan, Yaohua Mai
The development of hybrid tin (Sn)-lead (Pb) perovskite solar cells likely tackles the toxic problem with the power conversion efficiency (PCE) exceeding 17%. However, the stability problems, e.g. hysteresis effect, degeneration and oxidation, appear to be the bottleneck that limit its further development. Here, we innovatively introduced C60 at the grain boundaries throughout the CH3NH3Pb0.75Sn0.25I3 (MAPb0.75Sn0.25I3) thin film, playing a role not only in in situ passivating the interfaces and reducing the pinholes of perovskite thin films, but also in preventing the penetration of moisture and oxygen from ambient atmosphere...
September 18, 2017: Nanoscale
Vikash Malik, Antara Pal, Olivier Pravaz, Jérôme J Crassous, Simon Granville, Bernard Grobety, Ann M Hirt, Hervé Dietsch, Peter Schurtenberger
We describe the synthesis of hybrid magnetic ellipsoidal nanoparticles that consist of a mixture of two different iron oxide phases, hematite (α-Fe2O3) and maghemite (γ-Fe2O3), and characterize their magnetic field-driven self-assembly. We demonstrate that the relative amount of the two phases can be adjusted in a continuous way by varying the reaction time during the synthesis, leading to strongly varying magnetic properties of the particles. Not only does the saturation magnetization increase dramatically as the composition of the spindles changes from hematite to maghemite, but also the direction of the induced magnetic moment changes from being parallel to the short axis of the spindle to being perpendicular to it...
September 18, 2017: Nanoscale
Hamed Eskandarloo, Arkaye Kierulf, Alireza Abbaspourrad
Nano- and micromotors are machines designed to self-propel and-in the process of propelling themselves-perform specialized tasks like cleaning polluted waters. These motors offer distinct advantages over conventionally static decontamination methods, owing to their ability to move around and self-mix-which heightens the interaction between their active sites and target pollutants-thus improving their speed and efficiency, which could potentially decrease treatment times and costs. In the last decade, considerable research efforts have been expended on exploring various mechanisms by which these motors can self-propel and remove pollutants, proving that the removal of oil droplets, heavy metals, and organic compounds using these synthetic motors is possible...
September 18, 2017: Nanoscale
Xu Wu, Shengpeng Wang, Mingxing Li, Anqi Wang, Yangyang Zhou, Peng Li, Yitao Wang
Since its initial identification, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has been shown to be capable of selectively inducing apoptosis in cancer cells. However, translation of the encouraging preclinical studies of this cytokine into the clinic has been restricted by its extremely short half-life, the presence of resistant cancer cell populations, and its inefficient in vivo delivery. Recently, there has been exceptional progress in developing novel formulations to increase the circulatory half-life of TRAIL and new combinations to treat cancers that are resistant to TRAIL...
September 15, 2017: Nanoscale
Swathi Murthy, Henrik Pranov, Nikolaj A Feidenhans'l, Jonas S Madsen, Poul Erik Hansen, Henrik C Pedersen, Rafael Taboryski
Lab-scale plasmonic color printing using nano-structured and subsequently metallized surfaces have been demonstrated to provide vivid colors. However, upscaling these structures for large area manufacturing is extremely challenging due to the requirement of nanometer precision of metal thickness. In this study, we have investigated a plasmonic color meta-surface design that can be easily upscaled. We have demonstrated the feasibility of fabrication of these plasmonic color surfaces by a high-speed roll-to-roll method, comprising roll-to-roll extrusion coating at 10 m min(-1) creating a polymer foil having 100 nm deep pits of varying sub-wavelength diameter and pitch length...
September 15, 2017: Nanoscale
Akash Bachhuka, Bahman Delalat, Soraya Rasi Ghaemi, Stan Gronthos, Nicolas H Voelcker, Krasimir Vasilev
Advanced medical devices, treatments and therapies demand an understanding of the role of interfacial properties on the cellular response. This is particularly important in the emerging fields of cell therapies and tissue regeneration. In this study, we evaluate the role of surface nanotopography on the fate of human dental pulp derived stem cells (hDPSC). These stem cells have attracted interest because of their capacity to differentiate to a range of useful lineages but are relatively easy to isolate. We generated and utilized density gradients of gold nanoparticles which allowed us to examine, on a single substrate, the influence of nanofeature density and size on stem cell behavior...
September 15, 2017: Nanoscale
Zhi Jiang, Zhongti Sun, Yuqi Yang, Siyu Chen, Wenfeng Shangguan, Xiaojun Wu
First-principles calculations and experiments with PtOx on TiO2 surfaces were performed together to understand the interactions of metal oxides during the calcination process and their influence on the growth pattern of Pt on the TiO2 surface. Our calculations indicate that PtOx with a high concentration of oxygen binds more strongly to rutile than to anatase, indicating the formation of stronger interactions between Pt oxide and the rutile surface compared with anatase during the calcination stage under an oxidative atmosphere...
September 15, 2017: Nanoscale
B Sikora, P Kowalik, J Mikulski, K Fronc, I Kamińska, M Szewczyk, A Konopka, K Zajdel, R Minikayev, K Sobczak, W Zaleszczyk, A Borodziuk, J Rybusiński, J Szczytko, A Sienkiewicz, T Wojciechowski, P Stępień, M Frontczak-Baniewicz, M Łapiński, G Wilczyński, W Paszkowicz, A Twardowski, D Elbaum
Water-soluble upconversion nanoparticles (UCNPs), based on polyvinylpyrrolidone (PVP)-coated NaYF4:Er(3+),Yb(3+),Gd(3+), with various concentrations of Gd(3+) ions and relatively high upconversion efficiencies, were synthesized. The internalization and cytotoxicity of the thus obtained UCNPs were evaluated in three cell lines (HeLa, HEK293 and astrocytes). No cytotoxicity was observed even at concentrations of UCNPs up to 50 μg ml(-1). The fate of the UCNPs within the cells was studied by examining their upconversion emission spectra with confocal microscopy and confirming these observations with transmission electron microscopy...
September 15, 2017: Nanoscale
Kai Yin, Dongkai Chu, Xinran Dong, Cong Wang, Ji-An Duan, Jun He
Marine oil spills have induced severe water pollution and threatened sea ecosystems, which also result in a loss of energy resources. To deal with this problem, much work has been done for using superhydrophobic or superhydrophilic mesh for oil-water separation. Nevertheless, there are still great challenges in the rapid fabrication of extremely durable mesh with superwetting properties, particularly considering the highly efficient oil-water separation. In this study, we present a simple, efficient method to fabricate superhydrophilic and underwater superoleophobic stainless steel mesh surfaces with one-step femtosecond laser induced periodic nanoripple structures...
September 15, 2017: Nanoscale
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