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nano pillar

Patrice Simon
In this issue of ACS Nano, Luo et al. report the preparation of pillared two-dimensional (2D) Ti3C2 MXenes with controllable interlayer spacings between 1 and 2.708 nm. These materials were further intercalated by ion exchange with Sn(+IV) ions. The results show improved electrochemical performance due to improved ion accessibility into the 2D structure as well as the confinement effect, which limits volume expansion during the Li-alloying reaction. Beyond this specific example, the demonstration that the interlayer spacings of MXenes can be fine-tuned by creating pillared structures based on the spontaneous intercalation of surfactants opens new perspectives in the field of electrochemical energy storage...
March 10, 2017: ACS Nano
Jaime J Hernández, Miguel A Monclús, Iván Navarro-Baena, Felipe Viela, Jon M Molina-Aldareguia, Isabel Rodríguez
This paper presents a multifunctional polymer surface that provides superhydrophobicity and self-cleaning functions together with an enhancement in mechanical and electrical performance. These functionalities are produced by nanoimprinting high aspect ratio pillar arrays on polymeric matrix incorporating functional reinforcing elements. Two distinct matrix-filler systems are investigated specifically, Carbon Nanotube reinforced Polystyrene (CNT-PS) and Reduced Graphene Oxide reinforced Polyvinylidene Difluoride (RGO-PVDF)...
March 6, 2017: Scientific Reports
Haijie Zuo, Duk-Yong Choi, Xin Gai, Barry Luther-Davies, Baoping Zhang
We present a novel CMOS-compatible fabrication technique for convex micro-nano lens arrays (MNLAs) with high packing density on the wafer scale. By means of conformal chemical vapor deposition (CVD) of hydrogenated amorphous silicon (a-Si:H) following patterning of silicon pillars via electron beam lithography (EBL) and plasma etching, large areas of a close packed silicon lens array with the diameter from a few micrometers down to a few hundred nanometers was fabricated. The resulting structure shows excellent surface roughness and high uniformity...
February 20, 2017: Optics Express
Nazanin Farokhnia, Seyed Mohammad Sajadi, Peyman Irajizad, Hadi Ghasemi
Thermal management of high temperature systems through cooling droplets is limited by the existence of the Leidenfrost point (LFP), at which the formation of a continuous vapor film between a hot solid and a cooling droplet diminishes the heat transfer rate. This limit results in a bottleneck for the advancement of the wide spectrum of systems including high-temperature power generation, electronics/photonics, reactors, and spacecraft. Despite a long time effort on development of surfaces for suppression of this phenomenon, this limit has only shifted to higher temperatures, but still exists...
March 14, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Lei Tao, Sreeprasad Theruvakkattil Sreenivasan, Rouzbeh Shahsavari
Improving heat transfer in hybrid nano/microelectronic systems is a challenge, mainly due to the high thermal boundary resistance (TBR) across the interface. Herein, we focus on gallium nitride (GaN)/diamond interface-as a model system with various high power, high temperature, and optoelectronic applications-and perform extensive reverse nonequilibrium molecular dynamics simulations, decoding the interplay between the pillar length, size, shape, hierarchy, density, arrangement, system size, and the interfacial heat transfer mechanisms to substantially reduce TBR in GaN-on-diamond devices...
January 11, 2017: ACS Applied Materials & Interfaces
Muhammad Rizwan, Gary S L Peh, Heng-Pei Ang, Nyein Chan Lwin, Khadijah Adnan, Jodhbir S Mehta, Wui Siew Tan, Evelyn K F Yim
Naturally-bioactive hydrogels like gelatin provide favorable properties for tissue-engineering but lack sufficient mechanical strength for use as implantable tissue engineering substrates. Complex fabrication or multi-component additives can improve material strength, but often compromises other properties. Studies have shown gelatin methacrylate (GelMA) as a bioactive hydrogel with diverse tissue growth applications. We hypothesize that, with suitable material modifications, GelMA could be employed for growth and implantation of tissue-engineered human corneal endothelial cell (HCEC) monolayer...
March 2017: Biomaterials
Rui Hao, Aleksander A Tedstone, David J Lewis, Chris P Warrens, Kevin R West, Philip Howard, Sander Gaemers, Shen J Dillon, Paul O'Brien
Knowledge of their bulk physical properties often guides selection of appropriate tribological coating materials. However, these properties as well as the microstructure evolve dramatically under the extreme conditions imposed during mechanical wear. The dynamic response ultimately governs the material's wear performance; thus, understanding the dynamic evolution of the system is critical. This work characterizes the change in mechanical properties and microstructure as a function of wear cycles in model MoS2 films using a combination of nanowear testing, transmission electron microscopy, and site-specific nanopillar compression...
January 18, 2017: ACS Applied Materials & Interfaces
Xiaoyue Ni, Julia R Greer, Kaushik Bhattacharya, Richard D James, Xian Chen
Shape memory alloys that produce and recover from large deformation driven by martensitic transformation are widely exploited in biomedical devices and microactuators. Generally their actuation work degrades significantly within first a few cycles and is reduced at smaller dimensions. Further, alloys exhibiting unprecedented reversibility have relatively small superelastic strain, 0.7%. These raise the questions of whether high reversibility is necessarily accompanied by small work and strain and whether high work and strain is necessarily diminished at small scale...
December 14, 2016: Nano Letters
Yingnan Wu, Zheng Yang, Jaslyn Bee Khuan Law, Ai Yu He, Azlina A Abbas, Vinitha Denslin, Tunku Kamarul, James H P Hui, Eng Hin Lee
Stem cell differentiation is guided by contact with the physical microenvironment, influence by both topography and mechanical properties of the matrix. In this study, the combined effect of substratum nano-topography and mechanical stiffness in directing mesenchymal stem cell (MSC) chondrogenesis was investigated. Three polyesters of varying stiffness were thermally imprinted to create nano-grating or pillar patterns of the same dimension. The surface of the nano-patterned substrate was coated with chondroitin sulfate (CS) to provide an even surface chemistry, with cell-adhesive and chondro-inductive properties, across all polymeric substrates...
January 2017: Tissue Engineering. Part A
Zohar A Arnon, Andreas Vitalis, Aviad Levin, Thomas C T Michaels, Amedeo Caflisch, Tuomas P J Knowles, Lihi Adler-Abramovich, Ehud Gazit
The dynamic nature of supramolecular polymers has a key role in their organization. Yet, the manipulation of their dimensions and polarity remains a challenge. Here, the minimalistic diphenylalanine building block was applied to demonstrate control of nano-assemblies growth and shrinkage using microfluidics. To fine-tune differential local environments, peptide nanotubes were confined by micron-scale pillars and subjected to monomer flows of various saturation levels to control assembly and disassembly. The small-volume device allows the rapid adjustment of conditions within the system...
October 25, 2016: Nature Communications
Frances J Harding, Salvatore Surdo, Bahman Delalat, Chiara Cozzi, Roey Elnathan, Stan Gronthos, Nicolas H Voelcker, Giuseppe Barillaro
Ordered arrays of silicon nano- to microscale pillars are used to enable biomolecular trafficking into primary human cells, consistently demonstrating high transfection efficiency can be achieved with broader and taller pillars that reported to date. Cell morphology on the pillar arrays is often strikingly elongated. Investigation of the cellular interaction with the pillar reveals that cells are suspended on pillar tips and do not interact with the substrate between the pillars. While cells remain suspended on pillar tips, acute local deformation of the cell membrane was noted, allowing pillar tips to penetrate the cell interior, while retaining cell viability...
October 17, 2016: ACS Applied Materials & Interfaces
Zhenggang Zhang, Xiaoyue Xu, Shuwei Wang, Zhe Peng, Meng Liu, Jingjing Zhou, Cai Shen, Deyu Wang
A nanostructured protective structure, pillared by the copper nanoclusters and in situ filled with lithium oxide in the interspace, is constructed to efficiently improve the cyclic stability and lifetime of lithium metal electrodes. The porous structure of copper nanoclusters enables high specific surface area, locally reduced current density, and dendrite suppressing, while the filled lithium oxide leads to the structural stability and largely extends the electrode lifespan. As a result of the synergetic protection of the proposed structure, lithium metal could be fully discharged with efficiency ∼97% for more than 150 cycles in corrosive alkyl carbonate electrolytes, without dendrite formation...
October 12, 2016: ACS Applied Materials & Interfaces
Zeinab Jahed, Ramin Zareian, Yeung Yeung Chau, Brandon B Seo, Mary West, Ting Y Tsui, Weijia Wen, Mohammad R K Mofrad
Three-dimensional vertically aligned nano- and micropillars have emerged as promising tools for a variety of biological applications. Despite their increasing usage, the interaction mechanisms of cells with these rigid structures and their effect on single- and collective-cell behaviors are not well understood for different cell types. In the present study, we examine the response of glioma cells to micropillar arrays using a new microfabricated platform consisting of rigid silicon micropillar arrays of various shapes, sizes, and configurations fabricated on a single platform...
September 14, 2016: ACS Applied Materials & Interfaces
Benjamin H Wunsch, Joshua T Smith, Stacey M Gifford, Chao Wang, Markus Brink, Robert L Bruce, Robert H Austin, Gustavo Stolovitzky, Yann Astier
Deterministic lateral displacement (DLD) pillar arrays are an efficient technology to sort, separate and enrich micrometre-scale particles, which include parasites, bacteria, blood cells and circulating tumour cells in blood. However, this technology has not been translated to the true nanoscale, where it could function on biocolloids, such as exosomes. Exosomes, a key target of 'liquid biopsies', are secreted by cells and contain nucleic acid and protein information about their originating tissue. One challenge in the study of exosome biology is to sort exosomes by size and surface markers...
August 1, 2016: Nature Nanotechnology
Dinesh Kumar, K Konishi, Nikhil Kumar, S Miwa, A Fukushima, K Yakushiji, S Yuasa, H Kubota, C V Tomy, A Prabhakar, Y Suzuki, A Tulapurkar
The transfer of spin angular momentum to a nanomagnet from a spin polarized current provides an efficient means of controlling the magnetization direction in nanomagnets. A unique consequence of this spin torque is that the spontaneous oscillations of the magnetization can be induced by applying a combination of a dc bias current and a magnetic field. Here we experimentally demonstrate a different effect, which can drive a nanomagnet into spontaneous oscillations without any need of spin torque. For the demonstration of this effect, we use a nano-pillar of magnetic tunnel junction (MTJ) powered by a dc current and connected to a coplanar waveguide (CPW) lying above the free layer of the MTJ...
2016: Scientific Reports
Shuguang Wang, Tong Zhou, Dehui Li, Zhenyang Zhong
The scalable array of ordered nano-pillars with precisely controllable quantum nanostructures (QNs) are ideal candidates for the exploration of the fundamental features of cavity quantum electrodynamics. It also has a great potential in the applications of innovative nano-optoelectronic devices for the future quantum communication and integrated photon circuits. Here, we present a synthesis of such hybrid system in combination of the nanosphere lithography and the self-assembly during heteroepitaxy. The precise positioning and controllable evolution of self-assembled Ge QNs, including quantum dot necklace(QDN), QD molecule(QDM) and quantum ring(QR), on Si nano-pillars are readily achieved...
2016: Scientific Reports
Hadi Nazaripoor, Charles R Koch, Mohtada Sadrzadeh, Subir Bhattacharjee
To improve the electrically assisted patterning process and create smaller sized features with the higher active surface area, the combined thermocapillary-electrohydrodynamic (TC-EHD) instability of liquid nanofilms is considered. First, the 3-D thin film equation is rederived for nonisothermal films and then the influential factors on the dynamics and stability of thin liquid film are found using linear stability (LS) analysis. Nonlinear studies are also conducted to investigate the long-time evolution of the interface using an in-house developed Fortran code employing high order finite difference and adaptive time step solver for the spatial and time derivatives...
June 14, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Xin Yan, Pradeep Sharma
Conventional molecular dynamics simulations enable the elucidation of an astonishing array of phenomena inherent in the mechanical and chemical behavior of materials. Unfortunately, current computational limitations preclude accounting for processes whose transition times exceed, at best, microseconds. This limitation severely impacts, among others, a realistic assessment of slow-strain-rate mechanical behavior. In this work, using a simple paradigmatical model of a metallic nanopillar that is often the subject of experimental works, we attempt to circumvent the time-scale bottleneck of conventional molecular dynamics and provide novel physical insights into the rate-dependence of mechanical behavior of nanostructures...
June 8, 2016: Nano Letters
Jinxi Huang, Hao Hu, Zhewei Wang, Wenyuan Li, Ji Cang, Jianqi Shen, Hui Ye
In this paper, a nano-pillar array integrated near quantum dots (QDs), which serves as a Purcell cavity as well as a column antenna, is studied in order to enhance the spontaneous emission (SE) rate of low emission efficiency QDs. A systematic analysis for treating the isolated nano-pillar and loose ordered pillar is demonstrated by solving the electromagnetic field equations. As an illustrative example of potential applications, we proposed a new structure that Germanium (Ge) QDs are located in close proximity to the isolated Indium Tin Oxide (ITO) nano-pillar to raise its efficiency...
April 18, 2016: Optics Express
Cholho Lee, Kyung-Hoon Han, Kwon-Hyeon Kim, Jang-Joo Kim
We have demonstrated a simple and efficient method to fabricate OLEDs with enhanced out-coupling efficiencies and with low pixel blurring by inserting nano-pillar arrays prepared through the lateral phase separation of two immiscible polymers in a blend film. By selecting a proper solvent for the polymer and controlling the composition of the polymer blend, the nano-pillar arrays were formed directly after spin-coating of the polymer blend and selective removal of one phase, needing no complicated processes such as nano-imprint lithography...
March 21, 2016: Optics Express
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