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Heng Xie, Han-Xiong Huang, Yu-Jiang Peng
The fine nanostructure on the cicada wing of Cryptotympana atrata fabricius, which exhibits hydrophobicity and antireflectivity, is carefully examined. A promising strategy is proposed for facilely and successively replicating the natural functional nanostructure of the cicada wing onto polystyrene (PS) surfaces. First, a nickel replica with tapered nanopores is fabricated by combining electroless plating and subsequent electroplating with the natural cicada wing as an original template. Then, using microinjection compression molding, with the nickel replica as a template, the tapered nanopores are transcribed onto the PS surface, resulting in orderly and densely arranged nanopillars with a mean diameter of about 156 nm and a mean pitch of about 180 nm...
August 9, 2017: Nanoscale
Chaoran Liu, Jing Sun, Jing Li, Chenghao Xiang, Lufeng Che, Zuankai Wang, Xiaofeng Zhou
The directional and long-range droplet transportation is of great importance in microfluidic systems. However, it usually requires external energy input. Here we designed a wettability gradient surface that can drive droplet motion by structural topography. The surface has a wettability gradient range of over 150° from superhydrophobic to hydrophilic, which was achieved by etching silicon nanopillars and adjusting the area of hydrophilic silicon dioxide plane. We conducted force analysis to further reveal the mechanism for droplet self-propulsion, and found that the nanostructures are critical to providing a large driving force and small resistance force...
August 8, 2017: Scientific Reports
Aleksei Kabedev, Mark Ross-Lonergan, Vladimir Lobaskin
We study solute transport in a microfluidic channel, where the walls hold an array of tilted rigid nanopillars. By solving numerically the flow equations in the channel, we show that a combination of hydrodynamic effects with excluded volume interactions between the solute particles and the pillars leads to a hydrodynamic lift effect, which varies with the particle size, and depends in a strongly nonlinear fashion on the flow rate. We show that the lift force can be sufficiently strong to drive the solute accumulation or removal from the pillar region and can be switched to the opposite direction by variation of the shear rate or driving pressure...
July 28, 2017: Electrophoresis
Aron Hakonen, FengChao Wang, Per Ola Andersson, Håkan Wingfors, Tomas Rindzevicius, Michael Stenbæk Schmidt, Venugopal Rao Soma, Shicai Xu, YingQi Li, Anja Boisen, HengAn Wu
Picric acid (PA) is a severe environmental and security risk due to its unstable, toxic, and explosive properties. It is also challenging to detect in trace amounts and in situ because of its highly acidic and anionic character. Here, we assess sensing of PA under nonlaboratory conditions using surface-enhanced Raman scattering (SERS) silver nanopillar substrates and hand-held Raman spectroscopy equipment. The advancing elasto-capillarity effects are explained by molecular dynamics simulations. We obtain a SERS PA detection limit on the order of 20 ppt, corresponding attomole amounts, which together with the simple analysis methodology demonstrates that the presented approach is highly competitive for ultrasensitive analysis in the field...
February 24, 2017: ACS Sensors
Megan D Mulroe, Bernadeta R Srijanto, S Farzad Ahmadi, C Patrick Collier, Jonathan B Boreyko
It was recently discovered that condensation growing on a nanostructured superhydrophobic surface can spontaneously jump off the surface, triggered by naturally occurring coalescence events. Many reports have observed that droplets must grow to a size of order 10 μm before jumping is enabled upon coalescence; however, it remains unknown how the critical jumping size relates to the topography of the underlying nanostructure. Here, we characterize the dynamic behavior of condensation growing on six different superhydrophobic nanostructures, where the topography of the nanopillars was systematically varied...
July 18, 2017: ACS Nano
Liang Zhao, Huy Q Ta, Arezoo Dianat, Akash Soni, Artem Fediai, Wanjian Yin, Thomas Gemming, Barbara Trzebicka, Gianaurelio Cuniberti, Zhongfan Liu, Alicja Bachmatiuk, Mark H Rummeli
The promise of sp(2) nanomaterials remains immense, and ways to strategically combine and manipulate these nanostructures will further enhance their potential as well as advance nanotechnology as a whole. The scale of these structures requires precision at the atomic scale. In this sense electron microscopes are attractive as they offer both atomic imaging and a means to structurally modify structures. Here we show how Cr atoms can be used as physical linkers to connect carbon nanotubes and fullerenes to graphene...
July 12, 2017: Nano Letters
José Francisco Algorri, Braulio García-Cámara, Alexander Cuadrado, José Manuel Sánchez-Pena, Ricardo Vergaz
Dielectric metasurfaces based on high refractive index materials have been proposed recently. This type of structure has several advantages over their metallic counterparts. In this work, we demonstrate that dielectric metasurfaces can be theoretically designed satisfying Kerker's zero-forward condition. This is the first time that a dielectric metasurface based on this principle has been designed. A selective dielectric metasurface of silicon nanopillars is designed to work at 632.8 nm. This structure could work both as a dielectric mirror and a reject band filter...
July 7, 2017: Nanomaterials
Hidetaka Asoh, Ryota Imai, Hideki Hashimoto
GaAs nanopillar arrays were successfully fabricated by metal-assisted chemical etching using Au nanodot arrays. The nanodot arrays were formed on substrates by vacuum deposition through a porous alumina mask with an ordered array of openings. By using an etchant with a high acid concentration and low oxidant concentration at a relatively low temperature, the area surrounding the Au/GaAs interface could be etched selectively. Under the optimum conditions, Au-capped GaAs nanopillar arrays were formed with an ordered periodicity of 100 nm and pillar heights of 50 nm...
December 2017: Nanoscale Research Letters
Xiaoyin Sun, Takao Yasui, Takeshi Yanagida, Noritada Kaji, Sakon Rahong, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
Here, we developed a device integrated with a nanochannel and nanostructures to slow DNA translocation velocity. We found that translocation velocity of a single DNA molecule inside a nanochannel was decreased by pre-elongating it using some nanostructures, such as a shallow channel or nanopillars. This decrease of the translocation velocity was associated with the DNA mobility change, which is an intrinsic parameter of DNA molecules and unaffected by an electric field.
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Daren Xu, Fei Teng, Zhongshun Wang, Nan Lu
Surface-enhanced Raman scattering spectroscopy (SERS) is a nondestructive testing technique. To increase reproducibility of the SERS measurement is the key issue for improving the performance of SERS. In this article, we demonstrate an efficient method to improve the reproducibility, using confined silver nanoparticles (AgNPs) as a substrate. The AgNPs are formed uniformly on the tops of the prepared nanopillars by droplet-confined electroless deposition on the hydrophobic Si nanopillar arrays. The AgNPs present an excellent reproducibility in Raman measurement; the relative standard deviation is down to 3...
June 15, 2017: ACS Applied Materials & Interfaces
Jijie Huang, Leigang Li, Ping Lu, Zhimin Qi, Xing Sun, Xinghang Zhang, Haiyan Wang
A simple one-step pulsed laser deposition (PLD) method has been applied to grow self-assembled metal-oxide nanocomposite thin films. The as-deposited Co-BaZrO3 films show high epitaxial quality with ultra-fine vertically aligned Co nanopillars (diameter <5 nm) embedded in a BZO matrix. The diameter of the nanopillars can be further tuned by varying the deposition frequency. The metal and oxide phases grow separately without inter-diffusion or mixing. Taking advantage of this unique structure, a high saturation magnetization of ∼1375 emu cm(-3) in the Co-BaZrO3 nanocomposites has been achieved and further confirmed by Lorentz microscopy imaging in TEM...
June 2, 2017: Nanoscale
H C Cheng, M S Chen, B Y Peng, W T Lin, Y K Shen, Y H Wang
The conventional orthodontic power chain, often composed of polymer materials, has drawbacks such as a reduction of elasticity owing to water absorption as well as surface discoloration and staining resulting from food or beverages consumed by the patient. The goal of this study was to develop a surface treatment (nanoimprinting) for orthodontic power chains and to alleviate their shortcomings. A concave template (anodic alumina) was manufactured by anodization process using pure aluminum substrate by employing the nanoimprinting process...
2017: BioMed Research International
Tahta Amrillah, Yugandhar Bitla, Kwangwoo Shin, Tiannan Yang, Ying-Hui Hsieh, Yu-You Chiou, Heng-Jui Liu, Thi Hien Do, Dong Su, Yi-Chun Chen, Shien-Uang Jen, Long-Qing Chen, Kee Hoon Kim, Jenh-Yih Juang, Ying-Hao Chu
Magnetoelectric nanocomposites have been a topic of intense research due to their profound potential in the applications of electronic devices based on spintronic technology. Nevertheless, in spite of significant progress made in the growth of high-quality nanocomposite thin films, the substrate clamping effect still remains a major hurdle in realizing the ultimate magnetoelectric coupling. To overcome this obstacle, an alternative strategy of fabricating a self-assembled ferroelectric-ferrimagnetic bulk heterojunction on a flexible muscovite via van der Waals epitaxy is adopted...
June 27, 2017: ACS Nano
Yanbin Wang, Joseph Eugene Andrews, Liangbing Hu, Siddhartha Das
In this study, we employ molecular dynamics (MD) simulations to probe the spreading of a drop on a superhydrophobic (SH) surface. The SH surface consists of nanopillars and the drop spreads while being in the Cassie-Baxter (CB) state on the nanopillared surface. Most remarkably, unlike the spreading on non-SH surfaces, we witness that the spreading on SH surfaces is not dominated by the motion of the three-phase contact line (TPCL). Rather, the TPCL remains pinned at the edge of a nanopillar and the spreading is ensured by the liquid surface or the liquid-vapor interface (of this pinned TPCL) bending down and wetting the solid adjacent to the TPCL...
June 7, 2017: Physical Chemistry Chemical Physics: PCCP
Carmen Palacios-Berraquero, Dhiren M Kara, Alejandro R-P Montblanch, Matteo Barbone, Pawel Latawiec, Duhee Yoon, Anna K Ott, Marko Loncar, Andrea C Ferrari, Mete Atatüre
Quantum light emitters have been observed in atomically thin layers of transition metal dichalcogenides. However, they are found at random locations within the host material and usually in low densities, hindering experiments aiming to investigate this new class of emitters. Here, we create deterministic arrays of hundreds of quantum emitters in tungsten diselenide and tungsten disulphide monolayers, emitting across a range of wavelengths in the visible spectrum (610-680 nm and 740-820 nm), with a greater spectral stability than their randomly occurring counterparts...
May 22, 2017: Nature Communications
Artur Branny, Santosh Kumar, Raphaël Proux, Brian D Gerardot
An outstanding challenge in quantum photonics is scalability, which requires positioning of single quantum emitters in a deterministic fashion. Site positioning progress has been made in established platforms including defects in diamond and self-assembled quantum dots, albeit often with compromised coherence and optical quality. The emergence of single quantum emitters in layered transition metal dichalcogenide semiconductors offers new opportunities to construct a scalable quantum architecture. Here, using nanoscale strain engineering, we deterministically achieve a two-dimensional lattice of quantum emitters in an atomically thin semiconductor...
May 22, 2017: Nature Communications
Ha-Rim Seo, Hyung Joon Joo, Dae Hwan Kim, Long-Hui Cui, Seung-Cheol Choi, Jong-Ho Kim, Sung Woo Cho, Kyu Back Lee, Do-Sun Lim
Nanoscaled surface patterning is an emerging potential method of directing the fate of stem cells. We adopted nanoscaled pillar gradient patterned cell culture plates with three diameter gradients [280-360 (GP 280/360), 200-280 (GP 200/280), and 120-200 nm (GP 120/200)] and investigated their cell fate-modifying effect on multipotent fetal liver kinase 1-positive mesodermal precursor cells (Flk1(+) MPCs) derived from embryonic stem cells. We observed increased cell proliferation and colony formation of the Flk1(+) MPCs on the nanopattern plates...
May 12, 2017: ACS Applied Materials & Interfaces
Estela Baquedano, Ramses V Martinez, José M Llorens, Pablo A Postigo
Soft lithography allows for the simple and low-cost fabrication of nanopatterns with different shapes and sizes over large areas. However, the resolution and the aspect ratio of the nanostructures fabricated by soft lithography are limited by the depth and the physical properties of the stamp. In this work, silicon nanobelts and nanostructures were achieved by combining soft nanolithography patterning with optimized reactive ion etching (RIE) in silicon. Using polymethylmethacrylate (PMMA) nanopatterned layers with thicknesses ranging between 14 and 50 nm, we obtained silicon nanobelts in areas of square centimeters with aspect ratios up to ~1...
May 11, 2017: Nanomaterials
Xiaoyue Ni, Stefanos Papanikolaou, Gabriele Vajente, Rana X Adhikari, Julia R Greer
In small-scale metallic systems, collective dislocation activity has been correlated with size effects in strength and with a steplike plastic response under uniaxial compression and tension. Yielding and plastic flow in these samples is often accompanied by the emergence of multiple dislocation avalanches. Dislocations might be active preyield, but their activity typically cannot be discerned because of the inherent instrumental noise in detecting equipment. We apply alternate current load perturbations via dynamic mechanical analysis during quasistatic uniaxial compression experiments on single crystalline Cu nanopillars with diameters of 500 nm and compute dynamic moduli at frequencies 0...
April 14, 2017: Physical Review Letters
Ke Xiao, Yanping Zhao, Gang Ouyang, Xinlei Li
An analytic thermodynamic model has been established to quantitatively investigate the wetting states of droplets on nanopatterned surfaces. Based on the calculations for the free energies of droplets with the Wenzel state and the Cassie-Baxter state, it is found that the size and shape of nanostructured surfaces play crucial roles in wetting states. In detail, for nanohole-patterned surfaces, the deep and thin nanoholes lead to the Cassie-Baxter state, and contrarily, the shallow and thick nanoholes result in the Wenzel state...
December 2017: Nanoscale Research Letters
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