Nano-scale Materials and Nano-technology Processes in Environmental Protection

International Nuclear Information System (INIS)

Vissokov, Gh; Tzvetkoff, T.

2003-01-01

A number of environmental and energy technologies have benefited substantially from nano-scale technology: reduced waste and improved energy efficiency; environmentally friendly composite structures; waste remediation; energy conversion. In this report examples of current achievements and paradigm shifts are presented: from discovery to application; a nano structured materials; nanoparticles in the environment (plasma chemical preparation); nano-porous polymers and their applications in water purification; photo catalytic fluid purification; hierarchical self-assembled nano-structures for adsorption of heavy metals, etc. Several themes should be considered priorities in developing nano-scale processes related to environmental management: 1. To develop understanding and control of relevant processes, including protein precipitation and crystallisation, desorption of pollutants, stability of colloidal dispersion, micelle aggregation, microbe mobility, formation and mobility of nanoparticles, and tissue-nanoparticle interaction. Emphasis should be given to processes at phase boundaries (solid-liquid, solid-gas, liquid-gas) that involve mineral and organic soil components, aerosols, biomolecules (cells, microbes), bio tissues, derived components such as bio films and membranes, and anthropogenic additions (e.g. trace and heavy metals); 2. To carry out interdisciplinary research that initiates Noel approaches and adopts new methods for characterising surfaces and modelling complex systems to problems at interfaces and other nano-structures in the natural environment, including those involving biological or living systems. New technological advances such as optical traps, laser tweezers, and synchrotrons are extending examination of molecular and nano-scale processes to the single-molecule or single-cell level; 3. To integrate understanding of the roles of molecular and nano-scale phenomena and behaviour at the meso- and/or macro-scale over a period of time

Evaporation of nanoscale water on a uniformly complete wetting surface at different temperatures.

Science.gov (United States)

Guo, Yuwei; Wan, Rongzheng

2018-05-03

The evaporation of nanoscale water films on surfaces affects many processes in nature and industry. Using molecular dynamics (MD) simulations, we show the evaporation of a nanoscale water film on a uniformly complete wetting surface at different temperatures. With the increase in temperature, the growth of the water evaporation rate becomes slow. Analyses show that the hydrogen bond (H-bond) lifetimes and orientational autocorrelation times of the outermost water film decrease slowly with the increase in temperature. Compared to a thicker water film, the H-bond lifetimes and orientational autocorrelation times of a monolayer water film are much slower. This suggests that the lower evaporation rate of the monolayer water film on a uniformly complete wetting surface may be caused by the constriction of the water rotation due to the substrate. This finding may be helpful for controlling nanoscale water evaporation within a certain range of temperatures.

Quantum Transport Simulations of Nanoscale Materials

KAUST Repository

Obodo, Tobechukwu Joshua

2016-01-07

Nanoscale materials have many potential advantages because of their quantum confinement, cost and producibility by low-temperature chemical methods. Advancement of theoretical methods as well as the availability of modern high-performance supercomputers allow us to control and exploit their microscopic properties at the atomic scale, hence making it possible to design novel nanoscale molecular devices with interesting features (e.g switches, rectifiers, negative differential conductance, and high magnetoresistance). In this thesis, state-of-the-art theoretical calculations have been performed for the quantum transport properties of nano-structured materials within the framework of Density Functional Theory (DFT) and the Nonequilibrium Green\\'s Function (NEGF) formalism. The switching behavior of a dithiolated phenylene-vinylene oligomer sandwiched between Au(111) electrodes is investigated. The molecule presents a configurational bistability, which can be exploited in constructing molecular memories, switches, and sensors. We find that protonation of the terminating thiol groups is at the origin of the change in conductance. H bonding at the thiol group weakens the S-Au bond, and thus lowers the conductance. Our results allow us to re-interpret the experimental data originally attributing the conductance reduction to H dissociation. Also examined is current-induced migration of atoms in nanoscale devices that plays an important role for device operation and breakdown. We studied the migration of adatoms and defects in graphene and carbon nanotubes under finite bias. We demonstrate that current-induced forces within DFT are non-conservative, which so far has only been shown for model systems, and can lower migration barrier heights. Further, we investigated the quantum transport behavior of an experimentally observed diblock molecule by varying the amounts of phenyl (donor) and pyrimidinyl (acceptor) rings under finite bias. We show that a tandem configuration of

Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

Science.gov (United States)

Bond, Tiziana C; Miles, Robin; Davidson, James; Liu, Gang Logan

2015-11-03

Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

Science.gov (United States)

Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

2014-07-22

Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

Science.gov (United States)

Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

2015-07-14

Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

Selective nanoscale growth of lattice mismatched materials

Science.gov (United States)

Lee, Seung-Chang; Brueck, Steven R. J.

2017-06-20

Exemplary embodiments provide materials and methods of forming high-quality semiconductor devices using lattice-mismatched materials. In one embodiment, a composite film including one or more substantially-single-particle-thick nanoparticle layers can be deposited over a substrate as a nanoscale selective growth mask for epitaxially growing lattice-mismatched materials over the substrate.

Engineering of silicon surfaces at the micro- and nanoscales for cell adhesion and migration control

Directory of Open Access Journals (Sweden)

Torres-Costa V

2012-02-01

Full Text Available Vicente Torres-Costa1, Gonzalo Martínez-Muñoz2, Vanessa Sánchez-Vaquero3, Álvaro Muñoz-Noval1, Laura González-Méndez3, Esther Punzón-Quijorna1,4, Darío Gallach-Pérez1, Miguel Manso-Silván1, Aurelio Climent-Font1,4, Josefa P García-Ruiz3, Raúl J Martín-Palma11Department of Applied Physics, 2Department of Computer Science, 3Department of Molecular Biology, 4Centre for Micro Analysis of Materials, Universidad Autónoma de Madrid, Madrid, SpainAbstract: The engineering of surface patterns is a powerful tool for analyzing cellular communication factors involved in the processes of adhesion, migration, and expansion, which can have a notable impact on therapeutic applications including tissue engineering. In this regard, the main objective of this research was to fabricate patterned and textured surfaces at micron- and nanoscale levels, respectively, with very different chemical and topographic characteristics to control cell–substrate interactions. For this task, one-dimensional (1-D and two-dimensional (2-D patterns combining silicon and nanostructured porous silicon were engineered by ion beam irradiation and subsequent electrochemical etch. The experimental results show that under the influence of chemical and morphological stimuli, human mesenchymal stem cells polarize and move directionally toward or away from the particular stimulus. Furthermore, a computational model was developed aiming at understanding cell behavior by reproducing the surface distribution and migration of human mesenchymal stem cells observed experimentally.Keywords: surface patterns, silicon, hMSCs, ion-beam patterning

Spatial Manipulation of Heat Flow by Surface Boundaries at the Nanoscale

Science.gov (United States)

Malhotra, Abhinav; Maldovan, Martin

The precise manipulation of phonon transport properties is central to controlling thermal transport in semiconductor nanostructures. The physical understanding, prediction, and control of thermal phonon heat spectra and thermal conductivity accumulation functions - which establish the proportion of heat transported by phonons with different frequencies and mean-free-paths - has attracted significant attention in recent years. In this talk, we advance the possibilities of manipulating heat by spatially modulating thermal transport in nanostructures. We show that phonon scattering at interfaces impacts the most preferred physical pathway used by heat energy flow in thermal transport in nanostructures. The role of introducing boundaries with different surface conditions on resultant thermal flux is presented and methodologies to enhance these spatial modulations are discussed. This talk aims to advance the fundamental understanding on the nature of heat transport at nanoscale with potential applications in multiple research areas ranging from energy materials to optoelectronics.

Nanoscale footprints of self-running gallium droplets on GaAs surface.

Directory of Open Access Journals (Sweden)

Jiang Wu

Full Text Available In this work, the nanoscale footprints of self-driven liquid gallium droplet movement on a GaAs (001 surface will be presented and analyzed. The nanoscale footprints of a primary droplet trail and ordered secondary droplets along primary droplet trails are observed on the GaAs surface. A well ordered nanoterrace from the trail is left behind by a running droplet. In addition, collision events between two running droplets are investigated. The exposed fresh surface after a collision demonstrates a superior evaporation property. Based on the observation of droplet evolution at different stages as well as nanoscale footprints, a schematic diagram of droplet evolution is outlined in an attempt to understand the phenomenon of stick-slip droplet motion on the GaAs surface. The present study adds another piece of work to obtain the physical picture of a stick-slip self-driven mechanism in nanoscale, bridging nano and micro systems.

Organisation and Control of Nanoscale Structures on Au(111)

DEFF Research Database (Denmark)

Zhang, Jingdong; Chi, Qijin; Andersen, Jens Enevold Thaulov

2001-01-01

system is IDe arnino acid cystine in the adsorbed state. Af ter dissociation of its disulfide band cystine farms a highly ordered pattem controlled by adsorption via IDe liberated sulfur atoms and intermolecular hydrogen bonding. Further organisation at three different leveis by lateral interactions can...... constitutes a new case for the lise of in situ STM as a tool for manufacturing nanoscale pit structures on IDe Au(lll) surface at small bias voltage. Individually and in combination these data hold perspectives for preparation of atornically planar electrochernical surfaces willi controlled functionalisation...

Surface patterning for brittle amorphous material using nanoindenter-based mechanochemical nanofabrication

Energy Technology Data Exchange (ETDEWEB)

Park, Jeong Woo; Choi, Soo Chang; Kim, Yong Woo [Department of Nano Fusion Technology, Pusan National University, Miryang 627-706 (Korea, Republic of); Lee, Chae Moon [Samsung Electro-Mechanics, Busan 618-721 (Korea, Republic of); Lee, Deug Woo [Department of Nano System and Process Engineering, Pusan National University, Miryang 627-706 (Korea, Republic of)], E-mail: dwoolee@pusan.ac.kr

2008-02-27

This paper demonstrates a micro/nanoscale surface patterning technology for brittle material using mechanical and chemical processes. Fused silica was scratched with a Berkovich tip under various normal loads from several mN to several tens of mN with various tip rotations. The scratched substrate was then chemically etched in hydrofluoric solution to evaluate the chemical properties of the different deformed layers produced under various mechanical scratching conditions. Our results showed that either protruding or depressed patterns could be generated on the scratched surface after chemical etching by controlling the tip rotation, the normal load and the etching condition. In addition, the mask effect of amorphous material after mechanical scratching was controlled by conventional mechanical machining conditions such as contact area, chip formation, plastic flow and material removal.

Nanoscale surface characterization using laser interference microscopy

Science.gov (United States)

Ignatyev, Pavel S.; Skrynnik, Andrey A.; Melnik, Yury A.

2018-03-01

Nanoscale surface characterization is one of the most significant parts of modern materials development and application. The modern microscopes are expensive and complicated tools, and its use for industrial tasks is limited due to laborious sample preparation, measurement procedures, and low operation speed. The laser modulation interference microscopy method (MIM) for real-time quantitative and qualitative analysis of glass, metals, ceramics, and various coatings has a spatial resolution of 0.1 nm for vertical and up to 100 nm for lateral. It is proposed as an alternative to traditional scanning electron microscopy (SEM) and atomic force microscopy (AFM) methods. It is demonstrated that in the cases of roughness metrology for super smooth (Ra >1 nm) surfaces the application of a laser interference microscopy techniques is more optimal than conventional SEM and AFM. The comparison of semiconductor test structure for lateral dimensions measurements obtained with SEM and AFM and white light interferometer also demonstrates the advantages of MIM technique.

Quantum Materials at the Nanoscale - Final Report

Energy Technology Data Exchange (ETDEWEB)

Cooper, Stephen Lance [Univ. of Illinois, Urbana, IL (United States). Dept. of Physics

2016-01-11

The central aim of the Quantum Materials at the Nanoscale (QMN) cluster was to understand and control collective behavior involving the interplay of spins, orbitals, and charges, which governs many scientifically interesting and technologically important phenomena in numerous complex materials. Because these phenomena involve various competing interactions, and influence properties on many different length and energy scales in complex materials, tackling this important area of study motivated a collaborative effort that combined the diverse capabilities of QMN cluster experimentalists, the essential theoretical analysis provided by QMN cluster theorists, and the outstanding facilities and staff of the FSMRL. During the funding period 2007-2014, the DOE cluster grant for the Quantum Materials at the Nanoscale (QMN) cluster supported, at various times, 15 different faculty members (14 in Physics and 1 in Materials Science and Engineering), 7 postdoctoral research associates, and 57 physics and materials science PhD students. 41 of these PhD students have since graduated and have gone on to a variety of advanced technical positions at universities, industries, and national labs: 25 obtained postdoctoral positions at universities (14), industrial labs (2 at IBM), DOE national facilities (3 at Argonne National Laboratory, 1 at Brookhaven National Lab, 1 at Lawrence Berkeley National Lab, and 1 at Sandia National Lab), and other federal facilities (2 at NIST); 13 took various industrial positions, including positions at Intel (5), Quantum Design (1), Lasque Industries (1), Amazon (1), Bloomberg (1), and J.P. Morgan (1). Thus, the QMN grant provided the essential support for training a large number of technically advanced personnel who have now entered key national facilities, industries, and institutions. Additionally, during the period 2007-2015, the QMN cluster produced 159 publications (see pages 14-23), including 23 papers published in Physical Review Letters; 16

Nanoscale measurement of Nernst effect in two-dimensional charge density wave material 1T-TaS2

Science.gov (United States)

Wu, Stephen M.; Luican-Mayer, Adina; Bhattacharya, Anand

2017-11-01

Advances in nanoscale material characterization on two-dimensional van der Waals layered materials primarily involve their optical and electronic properties. The thermal properties of these materials are harder to access due to the difficulty of thermal measurements at the nanoscale. In this work, we create a nanoscale magnetothermal device platform to access the basic out-of-plane magnetothermal transport properties of ultrathin van der Waals materials. Specifically, the Nernst effect in the charge density wave transition metal dichalcogenide 1T-TaS2 is examined on nano-thin flakes in a patterned device structure. It is revealed that near the commensurate charge density wave (CCDW) to nearly commensurate charge density wave (NCCDW) phase transition, the polarity of the Nernst effect changes. Since the Nernst effect is especially sensitive to changes in the Fermi surface, this suggests that large changes are occurring in the out-of-plane electronic structure of 1T-TaS2, which are otherwise unresolved in just in-plane electronic transport measurements. This may signal a coherent evolution of out-of-plane stacking in the CCDW → NCCDW transition.

Tip-Enhanced Raman Scattering Microscopy: A Step toward Nanoscale Control of Intrinsic Molecular Properties

Science.gov (United States)

Yano, Taka-aki; Hara, Masahiko

2018-06-01

Tip-enhanced Raman scattering microscopy, a family of scanning probe microscopy techniques, has been recognized as a powerful surface analytical technique with both single-molecule sensitivity and angstrom-scale spatial resolution. This review covers the current status of tip-enhanced Raman scattering microscopy in surface and material nanosciences, including a brief history, the basic principles, and applications for the nanoscale characterization of a variety of nanomaterials. The focus is on the recent trend of combining tip-enhanced Raman scattering microscopy with various external stimuli such as pressure, voltage, light, and temperature, which enables the local control of the molecular properties and functions and also enables chemical reactions to be induced on a nanometer scale.

Nanoscale roughness and morphology affect the IsoElectric Point of titania surfaces.

Directory of Open Access Journals (Sweden)

Francesca Borghi

Full Text Available We report on the systematic investigation of the role of surface nanoscale roughness and morphology on the charging behaviour of nanostructured titania (TiO2 surfaces in aqueous solutions. IsoElectric Points (IEPs of surfaces have been characterized by direct measurement of the electrostatic double layer interactions between titania surfaces and the micrometer-sized spherical silica probe of an atomic force microscope in NaCl aqueous electrolyte. The use of a colloidal probe provides well-defined interaction geometry and allows effectively probing the overall effect of nanoscale morphology. By using supersonic cluster beam deposition to fabricate nanostructured titania films, we achieved a quantitative control over the surface morphological parameters. We performed a systematical exploration of the electrical double layer properties in different interaction regimes characterized by different ratios of characteristic nanometric lengths of the system: the surface rms roughness Rq, the correlation length ξ and the Debye length λD. We observed a remarkable reduction by several pH units of IEP on rough nanostructured surfaces, with respect to flat crystalline rutile TiO2. In order to explain the observed behavior of IEP, we consider the roughness-induced self-overlap of the electrical double layers as a potential source of deviation from the trend expected for flat surfaces.

Experimental Study of Electron and Phonon Dynamics in Nanoscale Materials by Ultrafast Laser Time-Domain Spectroscopy

Science.gov (United States)

Shen, Xiaohan

less than 100 nm was observed. The longitudinal acoustic phonon transport in silicon (Si) nanorod with confined diameter and length was investigated. The guided phonon modes in Si nanorod with different frequencies and wave vectors were observed. The mean-free-path of the guided phonons in Si nanorod was found to be larger than the effective phonon mean-free-path in Si film, because of the limited phonon scattering channels in Si nanorod. The phonon density of states and dispersion relation strongly depend on the size and boundary conditions of nanorod. Our work demonstrates the possibility of modifying the phonon transport properties in nanoscale materials by designing the size and boundary conditions, hence the control of thermal conductivity. In addition, the periodicity effect of nanostructures on acoustic phonon transport was investigated in silicon dioxide (SiO2) nanorod arrays. The lattice modes and mechanical eigenmodes were observed, and the pitch effect on lattice modes was discussed. A narrowband acoustic phonon spectroscopic technique with tunable frequency and spectral width throughout GHz frequency range has been developed to investigate the frequency-dependent acoustic phonon transport in nanoscale materials. The quadratic frequency dependence of acoustic attenuation of SiO2 and indium tin oxide (ITO) thin films was observed, and the acoustic attenuation of ITO was found to be larger than SiO2. Moreover, the acoustic control on mechanical resonance of nanoscale materials using the narrowband acoustic phonon source was demonstrated in tungsten thin film.

DOE A9024 Final Report Functional and Nanoscale Materials Systems: Frontier Programs of Science at the Frederick Seitz Materials Research Laboratory

Energy Technology Data Exchange (ETDEWEB)

Lewis, Jennifer A.

2009-03-24

The scientific programs of the FSMRL supported under the DOE A9024 Grant consisted of four interdisciplinary research clusters, as described. The clusters were led by Professors Tai Chiang (Physics), Jeffrey Moore (Chemistry), Paul Goldbart (Physics), and Steven Granick (Materials Science and Engineering). The completed work followed a dominant theme--Nanoscale Materials Systems--and emphasized studies of complex phenomena involving surfaces, interfaces, complex materials, dynamics, energetics, and structures and their transformations. A summary of our key accomplishments is provided for each cluster.

Quantum Transport Simulations of Nanoscale Materials

KAUST Repository

Obodo, Tobechukwu Joshua

2016-01-01

-performance supercomputers allow us to control and exploit their microscopic properties at the atomic scale, hence making it possible to design novel nanoscale molecular devices with interesting features (e.g switches, rectifiers, negative differential conductance, and high

Investigating Nanoscale Electrochemistry with Surface- and Tip-Enhanced Raman Spectroscopy.

Science.gov (United States)

Zaleski, Stephanie; Wilson, Andrew J; Mattei, Michael; Chen, Xu; Goubert, Guillaume; Cardinal, M Fernanda; Willets, Katherine A; Van Duyne, Richard P

2016-09-20

The chemical sensitivity of surface-enhanced Raman spectroscopy (SERS) methodologies allows for the investigation of heterogeneous chemical reactions with high sensitivity. Specifically, SERS methodologies are well-suited to study electron transfer (ET) reactions, which lie at the heart of numerous fundamental processes: electrocatalysis, solar energy conversion, energy storage in batteries, and biological events such as photosynthesis. Heterogeneous ET reactions are commonly monitored by electrochemical methods such as cyclic voltammetry, observing billions of electrochemical events per second. Since the first proof of detecting single molecules by redox cycling, there has been growing interest in examining electrochemistry at the nanoscale and single-molecule levels. Doing so unravels details that would otherwise be obscured by an ensemble experiment. The use of optical spectroscopies, such as SERS, to elucidate nanoscale electrochemical behavior is an attractive alternative to traditional approaches such as scanning electrochemical microscopy (SECM). While techniques such as single-molecule fluorescence or electrogenerated chemiluminescence have been used to optically monitor electrochemical events, SERS methodologies, in particular, have shown great promise for exploring electrochemistry at the nanoscale. SERS is ideally suited to study nanoscale electrochemistry because the Raman-enhancing metallic, nanoscale substrate duly serves as the working electrode material. Moreover, SERS has the ability to directly probe single molecules without redox cycling and can achieve nanoscale spatial resolution in combination with super-resolution or scanning probe microscopies. This Account summarizes the latest progress from the Van Duyne and Willets groups toward understanding nanoelectrochemistry using Raman spectroscopic methodologies. The first half of this Account highlights three techniques that have been recently used to probe few- or single-molecule electrochemical

Tuning the Friction of Silicon Surfaces Using Nanopatterns at the Nanoscale

Directory of Open Access Journals (Sweden)

Jing Han

2017-12-01

Full Text Available Friction and wear become significant at small scale lengths, particularly in MEMS/NEMS. Nanopatterns are regarded as a potential approach to solve these problems. In this paper, we investigated the friction behavior of nanopatterned silicon surfaces with a periodical rectangular groove array in dry and wear-less single-asperity contact at the nanoscale using molecular dynamics simulations. The synchronous and periodic oscillations of the normal load and friction force with the sliding distance were determined at frequencies defined by the nanopattern period. The linear load dependence of the friction force is always observed for the nanopatterned surface and is independent of the nanopattern geometry. We show that the linear friction law is a formal Amontons’ friction law, while the significant linear dependence of the friction force-versus-real contact area and real contact area-versus-normal load captures the general features of the nanoscale friction for the nanopatterned surface. Interestingly, the nanopattern increases the friction force at the nanoscale, and the desired friction reduction is also observed. The enlargement and reduction of the friction critically depended on the nanopattern period rather than the area ratio. Our simulation results reveal that the nanopattern can modulate the friction behavior at the nanoscale from the friction signal to the friction law and to the value of the friction force. Thus, elaborate nanopatterning is an effective strategy for tuning the friction behavior at the nanoscale.

The synthesis and properties of nanoscale ionic materials

KAUST Repository

Rodriguez, Robert Salgado; Herrer, Rafael; Bourlinos, Athanasios B.; Li, Ruipeng; Amassian, Aram; Archer, Lynden A.; Giannelis, Emmanuel P.

2010-01-01

In this article we discuss the effect of constituents on structure, flow, and thermal properties of nanoscale ionic materials (NIMs). NIMs are a new class of nanohybrids consisting of a nanometer-sized core, a charged corona covalently attached

Nanoscale/multilayer gradient materials for application in electromagnetic gun systems

Energy Technology Data Exchange (ETDEWEB)

Otooni, M.A. [Army Armament Research, Development and Engineering Center, Picatinny Arsenal, NJ (United States); Brown, I.G.; Anders, S.; Wang, Z. [Lawrence Berkeley Lab., CA (United States)

1996-12-31

Analysis of fired rails from electromagnetic railguns indicates severe surface damage occurs due to high current arcing and tribological mismatch. The authors have explored the behavior of several nanoscale multilayered materials as possible routes to improve the thermomechanical properties of the rail and armature materials. Structures investigated include (i) Ti-Co alloy on Ta-Cu alloy on dlc (diamond-like carbon) on stainless steel; (ii) Ti-Co alloy on Ta-Cu alloy on dlc on Cu, (iii) Ti-Co alloy on Ta-Cu on Cu; and (iv) Ti-Co on Ta-Cu alloy on Al. The alloys were all 50:50 at% and film thicknesses were fin the range 400--1,000 {angstrom}. The films were formed using a repetitively pulsed vacuum arc plasma deposition method with substrate biasing- and IBAD-like techniques. The surfaces were characterized by scanning electron microscopy, transmission electron microscopy, Rutherford backscattering spectroscopy, optical microscopy, microhardness measurements, arc erosion resistance and scratch resistance tests. Preliminary results show improvement in the microhardness, arc erosion resistance and scratch resistance, most especially for the dlc-coated surfaces. This kind of multilayered approach to the fabrication of electromagnetic railgun and armature surfaces could be important for future advanced Electromagnetic EM Gun systems.

Patterning high explosives at the nanoscale

Energy Technology Data Exchange (ETDEWEB)

Nafday, Omkar A.; Pitchimani, Rajasekar; Weeks, Brandon L. [Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409 (United States); Haaheim, Jason [NanoInk Inc., 8025 Lamon Ave., Skokie, IL 60077 (United States)

2006-10-15

For the first time, we have shown that spin coating and Dip pen nanolithography (DPN trademark) are simple methods of preparing energetic materials such as PETN and HMX on the nanoscale, requiring no heating of the energetic material. Nanoscale patterning has been demonstrated by the DPN method while continuous thin films were produced using the spin coating method. Results are presented for preparing continuous PETN thin films of nanometer thickness by the spin coating method and for controlling the architecture of arbitrary nanoscale patterns of PETN and HMX by the DPN method. These methods are simple for patterning energetic materials and can be extended beyond PETN and HMX, opening the door for fundamental studies at the nanoscale. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Radiation synthesis of the nano-scale materials

Energy Technology Data Exchange (ETDEWEB)

Yonghong, Ni; Zhicheng, Zhang; Xuewu, Ge; Xiangling, Xu [Department of Applied Chemistry, Univ. of Science and Technology of China, Hefei (China)

2000-03-01

Some recent research jobs on fabricating the nano-scale materials via {gamma}-irradiation in our laboratory are simply summarized in this paper. The main contents contain four aspects: (1) the preparation of metal alloy - powders; (2) the fabrication of polymer -metal nano-composites in aqueous solution, micro-emulsion and emulsion systems; (3) the synthesis of metal sulfide nano-particles and (4) the preparation of the ordered nano-structure materials. The corresponding preparation processes are also simply described. (author)

Radiation synthesis of the nano-scale materials

International Nuclear Information System (INIS)

Ni Yonghong; Zhang Zhicheng; Ge Xuewu; Xu Xiangling

2000-01-01

Some recent research jobs on fabricating the nano-scale materials via γ-irradiation in our laboratory are simply summarized in this paper. The main contents contain four aspects: (1) the preparation of metal alloy - powders; (2) the fabrication of polymer -metal nano-composites in aqueous solution, micro-emulsion and emulsion systems; (3) the synthesis of metal sulfide nano-particles and (4) the preparation of the ordered nano-structure materials. The corresponding preparation processes are also simply described. (author)

Biological Response of Human Bone Marrow-Derived Mesenchymal Stem Cells to Commercial Tantalum Coatings with Microscale and Nanoscale Surface Topographies

Science.gov (United States)

Skoog, Shelby A.; Kumar, Girish; Goering, Peter L.; Williams, Brian; Stiglich, Jack; Narayan, Roger J.

2016-06-01

Tantalum is a promising orthopaedic implant coating material due to its robust mechanical properties, corrosion resistance, and excellent biocompatibility. Previous studies have demonstrated improved biocompatibility and tissue integration of surface-treated tantalum coatings compared to untreated tantalum. Surface modification of tantalum coatings with biologically inspired microscale and nanoscale features may be used to evoke optimal tissue responses. The goal of this study was to evaluate commercial tantalum coatings with nanoscale, sub-microscale, and microscale surface topographies for orthopaedic and dental applications using human bone marrow-derived mesenchymal stem cells (hBMSCs). Tantalum coatings with different microscale and nanoscale surface topographies were fabricated using a diffusion process or chemical vapor deposition. Biological evaluation of the tantalum coatings using hBMSCs showed that tantalum coatings promote cellular adhesion and growth. Furthermore, hBMSC adhesion to the tantalum coatings was dependent on surface feature characteristics, with enhanced cell adhesion on sub-micrometer- and micrometer-sized surface topographies compared to hybrid nano-/microstructures. Nanostructured and microstructured tantalum coatings should be further evaluated to optimize the surface coating features to promote osteogenesis and enhance osseointegration of tantalum-based orthopaedic implants.

Crystallization of high-strength nano-scale leucite glass-ceramics.

Science.gov (United States)

Theocharopoulos, A; Chen, X; Wilson, R M; Hill, R; Cattell, M J

2013-11-01

Fine-grained, high strength, translucent leucite dental glass-ceramics are synthesized via controlled crystallization of finely milled glass powders. The objectives of this study were to utilize high speed planetary milling of an aluminosilicate glass for controlled surface crystallization of nano-scale leucite glass-ceramics and to test the biaxial flexural strength. An aluminosilicate glass was synthesized, attritor or planetary milled and heat-treated. Glasses and glass-ceramics were characterized using particle size analysis, X-ray diffraction and scanning electron microscopy. Experimental (fine and nanoscale) and commercial (Ceramco-3, IPS Empress Esthetic) leucite glass-ceramics were tested using the biaxial flexural strength (BFS) test. Gaussian and Weibull statistics were applied. Experimental planetary milled glass-ceramics showed an increased leucite crystal number and nano-scale median crystal sizes (0.048-0.055 μm(2)) as a result of glass particle size reduction and heat treatments. Experimental materials had significantly (p0.05) strength difference. All other groups' mean BFS and characteristic strengths were found to be significantly different (pglass-ceramics with high flexural strength. These materials may help to reduce problems associated with brittle fracture of all-ceramic restorations and give reduced enamel wear. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Inherent wettability of different rock surfaces at nanoscale: a theoretical study

Science.gov (United States)

Chang, Xiao; Xue, Qingzhong; Li, Xiaofang; Zhang, Jianqiang; Zhu, Lei; He, Daliang; Zheng, Haixia; Lu, Shuangfang; Liu, Zilong

2018-03-01

Investigating the inherent wettability of rock surfaces at nanoscale is of great importance in ore floatation and oil recovery field. Using molecular dynamics simulations, we systematically study the wetting behavior of water on different rock surfaces (silica, calcite, gypsum, halite and graphite) at nanoscale. It is demonstrated that the inherent rock wettability follows the order of gypsum > calcite > halite > silica > graphite. Remarkably, we also manifest that the polarity of oil molecules can affect the water contact angles on silica surface. For example, the water contact angles on silica surface in hexane, dodecane, thiophene and toluene are 58 ± 2°, 63 ± 3°, 90 ± 1°, 118 ± 1°, respectively. Furthermore, we investigate the wetting behavior of water on heterogeneous rock surfaces and find that water molecules can move from hydrophobic surface to hydrophilic surface.

Nanoscale surface modifications of medically relevant metals: state-of-the art and perspectives

Science.gov (United States)

Variola, Fabio; Brunski, John B.; Orsini, Giovanna; Tambasco de Oliveira, Paulo; Wazen, Rima; Nanci, Antonio

2011-02-01

Evidence that nanoscale surface properties stimulate and guide various molecular and biological processes at the implant/tissue interface is fostering a new trend in designing implantable metals. Cutting-edge expertise and techniques drawn from widely separated fields, such as nanotechnology, materials engineering and biology, have been advantageously exploited to nanoengineer surfaces in ways that control and direct these processes in predictable manners. In this review, we present and discuss the state-of-the-art of nanotechnology-based approaches currently adopted to modify the surface of metals used for orthopedic and dental applications, and also briefly consider their use in the cardiovascular field. The effects of nanoengineered surfaces on various in vitro molecular and cellular events are firstly discussed. This review also provides an overview of in vivo and clinical studies with nanostructured metallic implants, and addresses the potential influence of nanotopography on biomechanical events at interfaces. Ultimately, the objective of this work is to give the readership a comprehensive picture of the current advances, future developments and challenges in the application of the infinitesimally small to biomedical surface science. We believe that an integrated understanding of the in vitro and particularly of the in vivo behavior is mandatory for the proper exploitation of nanostructured implantable metals and, indeed, of all biomaterials.

Alternative surfacing materials for weed control at BC Hydro substations

International Nuclear Information System (INIS)

Wells, T.C.; Shrimpton, G.M.

1997-01-01

A two year study was conducted by BC Hydro in which a variety of surfacing materials were tested for their suitability for use in substations. Ideally, surfacing materials should have the following characteristics: high electrical resistivity in both dry and wet conditions, resistance to invasion by weeds, good driveability, good drainage, non-flammable, reasonably priced, no dust to foul conductors, and be aesthetically pleasing. Trials at Vernon Koksilah, and Ingledow substations were conducted to test the materials. A qualitative estimate of the amount of weed control provided by each material was recorded. The trials were meant to provide operational recommendations and screening information to allow for future testing of promising materials or combination of materials. Results showed that no single material meets all the desired criteria. The surfaces that best combined good weed control, electrical resistance and surface stability was a 15 cm deep layer of crushed gravel, especially if underlain by a layer of geotextile. 4 refs., 3 tabs., 1 fig

Simulations of surface stress effects in nanoscale single crystals

Science.gov (United States)

Zadin, V.; Veske, M.; Vigonski, S.; Jansson, V.; Muszinsky, J.; Parviainen, S.; Aabloo, A.; Djurabekova, F.

2018-04-01

Onset of vacuum arcing near a metal surface is often associated with nanoscale asperities, which may dynamically appear due to different processes ongoing in the surface and subsurface layers in the presence of high electric fields. Thermally activated processes, as well as plastic deformation caused by tensile stress due to an applied electric field, are usually not accessible by atomistic simulations because of the long time needed for these processes to occur. On the other hand, finite element methods, able to describe the process of plastic deformations in materials at realistic stresses, do not include surface properties. The latter are particularly important for the problems where the surface plays crucial role in the studied process, as for instance, in the case of plastic deformations at a nanovoid. In the current study by means of molecular dynamics (MD) and finite element simulations we analyse the stress distribution in single crystal copper containing a nanovoid buried deep under the surface. We have developed a methodology to incorporate the surface effects into the solid mechanics framework by utilizing elastic properties of crystals, pre-calculated using MD simulations. The method leads to computationally efficient stress calculations and can be easily implemented in commercially available finite element software, making it an attractive analysis tool.

Capillary-induced crack healing between surfaces of nanoscale roughness.

Science.gov (United States)

Soylemez, Emrecan; de Boer, Maarten P

2014-10-07

Capillary forces are important in nature (granular materials, insect locomotion) and in technology (disk drives, adhesion). Although well studied in equilibrium state, the dynamics of capillary formation merit further investigation. Here, we show that microcantilever crack healing experiments are a viable experimental technique for investigating the influence of capillary nucleation on crack healing between rough surfaces. The average crack healing velocity, v̅, between clean hydrophilic polycrystalline silicon surfaces of nanoscale roughness is measured. A plot of v̅ versus energy release rate, G, reveals log-linear behavior, while the slope |d[log(v̅)]/dG| decreases with increasing relative humidity. A simplified interface model that accounts for the nucleation time of water bridges by an activated process is developed to gain insight into the crack healing trends. This methodology enables us to gain insight into capillary bridge dynamics, with a goal of attaining a predictive capability for this important microelectromechanical systems (MEMS) reliability failure mechanism.

Fabrication of ordered arrays of micro- and nanoscale features with control over their shape and size via templated solid-state dewetting.

Science.gov (United States)

Ye, Jongpil

2015-05-08

Templated solid-state dewetting of single-crystal films has been shown to be used to produce regular patterns of various shapes. However, the materials for which this patterning method is applicable, and the size range of the patterns produced are still limited. Here, it is shown that ordered arrays of micro- and nanoscale features can be produced with control over their shape and size via solid-state dewetting of patches patterned from single-crystal palladium and nickel films of different thicknesses and orientations. The shape and size characteristics of the patterns are found to be widely controllable with varying the shape, width, thickness, and orientation of the initial patches. The morphological evolution of the patches is also dependent on the film material, with different dewetting behaviors observed in palladium and nickel films. The mechanisms underlying the pattern formation are explained in terms of the influence on Rayleigh-like instability of the patch geometry and the surface energy anisotropy of the film material. This mechanistic understanding of pattern formation can be used to design patches for the precise fabrication of micro- and nanoscale structures with the desired shapes and feature sizes.

Processing used nuclear fuel with nanoscale control of uranium and ultrafiltration

Energy Technology Data Exchange (ETDEWEB)

Wylie, Ernest M.; Peruski, Kathryn M.; Prizio, Sarah E. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Bridges, Andrea N.A.; Rudisill, Tracy S.; Hobbs, David T. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Phillip, William A. [Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States); Burns, Peter C., E-mail: pburns@nd.edu [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States)

2016-05-15

Current separation and purification technologies utilized in the nuclear fuel cycle rely primarily on liquid–liquid extraction and ion-exchange processes. Here, we report a laboratory-scale aqueous process that demonstrates nanoscale control for the recovery of uranium from simulated used nuclear fuel (SIMFUEL). The selective, hydrogen peroxide induced oxidative dissolution of SIMFUEL material results in the rapid assembly of persistent uranyl peroxide nanocluster species that can be separated and recovered at moderate to high yield from other process-soluble constituents using sequestration-assisted ultrafiltration. Implementation of size-selective physical processes like filtration could results in an overall simplification of nuclear fuel cycle technology, improving the environmental consequences of nuclear energy and reducing costs of processing. - Highlights: • Nanoscale control in irradiated fuel reprocessing. • Ultrafiltration to recover uranyl cage clusters. • Alternative to solvent extraction for uranium purification.

Nanoscale measurement of Nernst effect in two-dimensional charge density wave material 1T-TaS₂

Energy Technology Data Exchange (ETDEWEB)

Wu, Stephen M. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA; Luican-Mayer, Adina [Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada; Bhattacharya, Anand [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439, USA

2017-11-27

Advances in nanoscale material characterization on two-dimensional van der Waals layered materials primarily involve their optical and electronic properties. The thermal properties of these materials are harder to access due to the difficulty of thermal measurements at the nanoscale. In this work, we create a nanoscale magnetothermal device platform to access the basic out-of-plane magnetothermal transport properties of ultrathin van der Waals materials. Specifically, the Nernst effect in the charge density wave transition metal dichalcogenide 1T-TaS₂ is examined on nano-thin flakes in a patterned device structure. It is revealed that near the commensurate charge density wave (CCDW) to nearly commensurate charge density wave (NCCDW) phase transition, the polarity of the Nernst effect changes. Since the Nernst effect is especially sensitive to changes in the Fermi surface, this suggests that large changes are occurring in the out-of-plane electronic structure of 1T-TaS₂, which are otherwise unresolved in just in-plane electronic transport measurements. This may signal a coherent evolution of out-of-plane stacking in the CCDW! NCCDW transition.

Using mathematical models to understand the effect of nanoscale roughness on protein adsorption for improving medical devices

Directory of Open Access Journals (Sweden)

Ercan B

2013-09-01

Full Text Available Batur Ercan,1 Dongwoo Khang,2 Joseph Carpenter,3 Thomas J Webster1 1Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 2School of Materials Science and Engineering and Center for PRC and RIGET, Gyeongsang National University, Jinju, South Korea; 3School of Medicine, Stanford University, Stanford, CA, USA Abstract: Surface roughness and energy significantly influence protein adsorption on to biomaterials, which, in turn, controls select cellular adhesion to determine the success and longevity of an implant. To understand these relationships at a fundamental level, a model was originally proposed by Khang et al to correlate nanoscale surface properties (specifically, nanoscale roughness and energy to protein adsorption, which explained the greater cellular responses on nanostructured surfaces commonly reported in the literature today. To test this model for different surfaces from what was previously used to develop that model, in this study we synthesized highly ordered poly(lactic-co-glycolic acid surfaces of identical chemistry but altered nanoscale surface roughness and energy using poly(dimethylsiloxane molds of polystyrene beads. Fibronectin and collagen type IV adsorption studies showed a linear adsorption behavior as the surface nanoroughness increased. This supported the general trends observed by Khang et al. However, when fitting such data to the mathematical model established by Khang et al, a strong correlation did not result. Thus, this study demonstrated that the equation proposed by Khang et al to predict protein adsorption should be modified to accommodate for additional nanoscale surface property contributions (ie, surface charge to make the model more accurate. In summary, results from this study provided an important step in developing future mathematical models that can correlate surface properties (such as nanoscale roughness and surface energy to initial protein adsorption events important to

Nanoscale crystallinity modulates cell proliferation on plasma sprayed surfaces

Energy Technology Data Exchange (ETDEWEB)

Smith, Alan M. [School of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH (United Kingdom); Paxton, Jennifer Z.; Hung, Yi-Pei; Hadley, Martin J.; Bowen, James; Williams, Richard L. [School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom); Grover, Liam M., E-mail: l.m.grover@bham.ac.uk [School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom)

2015-03-01

Calcium phosphate coatings have been applied to the surface of metallic prostheses to mediate hard and soft tissue attachment for more than 40 years. Most coatings are formed of high purity hydroxyapatite, and coating methods are often designed to produce highly crystalline surfaces. It is likely however, that coatings of lower crystallinity can facilitate more rapid tissue attachment since the surface will exhibit a higher specific surface area and will be considerably more reactive than a comparable highly crystalline surface. Here we test this hypothesis by growing a population of MC3T3 osteoblast-like cells on the surface of two types of hip prosthesis with similar composition, but with differing crystallinity. The surfaces with lower crystallinity facilitated more rapid cell attachment and increased proliferation rate, despite having a less heterogeneous surface topography. This work highlights that the influence of the crystallinity of HA at the nano-scale is dominant over macro-scale topography for cell adhesion and growth. Furthermore, crystallinity could be easily adjusted by without compromising coating purity. These findings could facilitate designing novel coated calcium phosphate surfaces that more rapidly bond tissue following implantation. - Highlights: • Crystallinity of HA at the nano-scale was dominant over macro-scale topography. • Lower crystallinity caused rapid cell attachment and proliferation rate. • Crystallinity could be easily adjusted by without compromising coating purity.

Nanoscale crystallinity modulates cell proliferation on plasma sprayed surfaces

International Nuclear Information System (INIS)

Smith, Alan M.; Paxton, Jennifer Z.; Hung, Yi-Pei; Hadley, Martin J.; Bowen, James; Williams, Richard L.; Grover, Liam M.

2015-01-01

Calcium phosphate coatings have been applied to the surface of metallic prostheses to mediate hard and soft tissue attachment for more than 40 years. Most coatings are formed of high purity hydroxyapatite, and coating methods are often designed to produce highly crystalline surfaces. It is likely however, that coatings of lower crystallinity can facilitate more rapid tissue attachment since the surface will exhibit a higher specific surface area and will be considerably more reactive than a comparable highly crystalline surface. Here we test this hypothesis by growing a population of MC3T3 osteoblast-like cells on the surface of two types of hip prosthesis with similar composition, but with differing crystallinity. The surfaces with lower crystallinity facilitated more rapid cell attachment and increased proliferation rate, despite having a less heterogeneous surface topography. This work highlights that the influence of the crystallinity of HA at the nano-scale is dominant over macro-scale topography for cell adhesion and growth. Furthermore, crystallinity could be easily adjusted by without compromising coating purity. These findings could facilitate designing novel coated calcium phosphate surfaces that more rapidly bond tissue following implantation. - Highlights: • Crystallinity of HA at the nano-scale was dominant over macro-scale topography. • Lower crystallinity caused rapid cell attachment and proliferation rate. • Crystallinity could be easily adjusted by without compromising coating purity

Nanoscale deformation measurements for reliability assessment of material interfaces

Science.gov (United States)

Keller, Jürgen; Gollhardt, Astrid; Vogel, Dietmar; Michel, Bernd

2006-03-01

With the development and application of micro/nano electronic mechanical systems (MEMS, NEMS) for a variety of market segments new reliability issues will arise. The understanding of material interfaces is the key for a successful design for reliability of MEMS/NEMS and sensor systems. Furthermore in the field of BIOMEMS newly developed advanced materials and well known engineering materials are combined despite of fully developed reliability concepts for such devices and components. In addition the increasing interface-to volume ratio in highly integrated systems and nanoparticle filled materials are challenges for experimental reliability evaluation. New strategies for reliability assessment on the submicron scale are essential to fulfil the needs of future devices. In this paper a nanoscale resolution experimental method for the measurement of thermo-mechanical deformation at material interfaces is introduced. The determination of displacement fields is based on scanning probe microscopy (SPM) data. In-situ SPM scans of the analyzed object (i.e. material interface) are carried out at different thermo-mechanical load states. The obtained images are compared by grayscale cross correlation algorithms. This allows the tracking of local image patterns of the analyzed surface structure. The measurement results are full-field displacement fields with nanometer resolution. With the obtained data the mixed mode type of loading at material interfaces can be analyzed with highest resolution for future needs in micro system and nanotechnology.

Environmental, Health, and Safety Research Needs for Engineered Nanoscale Materials

National Research Council Canada - National Science Library

Alderson, Norris; Alexander, Catherine; Merzbacher, Celia; Chernicoff, William; Middendorf, Paul; Beck, Nancy; Chow, Flora; Poster, Dianne; Danello, Mary Ann; Barrera, Enriqueta

2006-01-01

...) research and information needs related to understanding and management of potential risks of engineered nanoscale materials that may be used, for example, in commercial or consumer products, medical...

Multifunctional-layered materials for creating membrane-restricted nanodomains and nanoscale imaging

Energy Technology Data Exchange (ETDEWEB)

Srinivasan, P., E-mail: prasri@ece.ucsb.edu, E-mail: srinivasan@lifesci.ucsb.edu [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA and Neuroscience Research Institute, University of California, Santa Barbara, California 93106 (United States)

2016-01-18

Experimental platform that allows precise spatial positioning of biomolecules with an exquisite control at nanometer length scales is a valuable tool to study the molecular mechanisms of membrane bound signaling. Using micromachined thin film gold (Au) in layered architecture, it is possible to add both optical and biochemical functionalities in in vitro. Towards this goal, here, I show that docking of complementary DNA tethered giant phospholiposomes on Au surface can create membrane-restricted nanodomains. These nanodomains are critical features to dissect molecular choreography of membrane signaling complexes. The excited surface plasmon resonance modes of Au allow label-free imaging at diffraction-limited resolution of stably docked DNA tethered phospholiposomes, and lipid-detergent bicelle structures. Such multifunctional building block enables realizing rigorously controlled in vitro set-up to model membrane anchored biological signaling, besides serving as an optical tool for nanoscale imaging.

Formation and Characterization of Stacked Nanoscale Layers of Polymers and Silanes on Silicon Surfaces

Science.gov (United States)

Ochoa, Rosie; Davis, Brian; Conley, Hiram; Hurd, Katie; Linford, Matthew R.; Davis, Robert C.

2008-10-01

Chemical surface patterning at the nanoscale is a critical component of chemically directed assembly of nanoscale devices or sensitive biological molecules onto surfaces. Complete and consistent formation of nanoscale layers of silanes and polymers is a necessary first step for chemical patterning. We explored methods of silanizing silicon substrates for the purpose of functionalizing the surfaces. The chemical functionalization, stability, flatness, and repeatability of the process was characterized by use of ellipsometry, water contact angle, and Atomic Force Microscopy (AFM). We found that forming the highest quality functionalized surfaces was accomplished through use of chemical vapor deposition (CVD). Specifically, surfaces were plasma cleaned and hydrolyzed before the silane was applied. A polymer layer less then 2 nm in thickness was electrostatically bound to the silane layer. The chemical functionalization, stability, flatness, and repeatability of the process was also characterized for the polymer layer using ellipsometry, water contact angle, and AFM.

Stochastic clustering of material surface under high-heat plasma load

Science.gov (United States)

Budaev, Viacheslav P.

2017-11-01

The results of a study of a surface formed by high-temperature plasma loads on various materials such as tungsten, carbon and stainless steel are presented. High-temperature plasma irradiation leads to an inhomogeneous stochastic clustering of the surface with self-similar granularity - fractality on the scale from nanoscale to macroscales. Cauliflower-like structure of tungsten and carbon materials are formed under high heat plasma load in fusion devices. The statistical characteristics of hierarchical granularity and scale invariance are estimated. They differ qualitatively from the roughness of the ordinary Brownian surface, which is possibly due to the universal mechanisms of stochastic clustering of material surface under the influence of high-temperature plasma.

Nanoscale inhomogeneity and photoacid generation dynamics in extreme ultraviolet resist materials

Science.gov (United States)

Wu, Ping-Jui; Wang, Yu-Fu; Chen, Wei-Chi; Wang, Chien-Wei; Cheng, Joy; Chang, Vencent; Chang, Ching-Yu; Lin, John; Cheng, Yuan-Chung

2018-03-01

The development of extreme ultraviolet (EUV) lithography towards the 22 nm node and beyond depends critically on the availability of resist materials that meet stringent control requirements in resolution, line edge roughness, and sensitivity. However, the molecular mechanisms that govern the structure-function relationships in current EUV resist systems are not well understood. In particular, the nanoscale structures of the polymer base and the distributions of photoacid generators (PAGs) should play a critical roles in the performance of a resist system, yet currently available models for photochemical reactions in EUV resist systems are exclusively based on homogeneous bulk models that ignore molecular-level details of solid resist films. In this work, we investigate how microscopic molecular organizations in EUV resist affect photoacid generations in a bottom-up approach that describes structure-dependent electron-transfer dynamics in a solid film model. To this end, molecular dynamics simulations and stimulated annealing are used to obtain structures of a large simulation box containing poly(4-hydroxystyrene) (PHS) base polymers and triphenylsulfonium based PAGs. Our calculations reveal that ion-pair interactions govern the microscopic distributions of the polymer base and PAG molecules, resulting in a highly inhomogeneous system with nonuniform nanoscale chemical domains. Furthermore, the theoretical structures were used in combination of quantum chemical calculations and the Marcus theory to evaluate electron transfer rates between molecular sites, and then kinetic Monte Carlo simulations were carried out to model electron transfer dynamics with molecular structure details taken into consideration. As a result, the portion of thermalized electrons that are absorbed by the PAGs and the nanoscale spatial distribution of generated acids can be estimated. Our data reveal that the nanoscale inhomogeneous distributions of base polymers and PAGs strongly affect the

Quantitative nanoscale surface voltage measurement on organic semiconductor blends

International Nuclear Information System (INIS)

Cuenat, Alexandre; Muñiz-Piniella, Andrés; Muñoz-Rojo, Miguel; Murphy, Craig E; Tsoi, Wing C

2012-01-01

We report on the validation of a method based on Kelvin probe force microscopy (KPFM) able to measure the different phases and the relative work function of polymer blend heterojunctions at the nanoscale. The method does not necessitate complex ultra-high vacuum setup. The quantitative information that can be extracted from the topography and the Kelvin probe measurements is critically analysed. Surface voltage difference can be observed at the nanoscale on poly(3-hexyl-thiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) blends and dependence on the annealing condition and the regio-regularity of P3HT is observed. (paper)

Scanning microwave microscopy technique for nanoscale characterization of magnetic materials

Energy Technology Data Exchange (ETDEWEB)

Joseph, C.H., E-mail: hadlee.joseph@artov.imm.cnr.it [National Research Council, Institute for Microelectronics and Microsystems (CNR-IMM), Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Department of Electronics Engineering, University of Rome “Tor Vergata”, Via del Politecnico 1, 00133 Rome (Italy); Sardi, G.M. [National Research Council, Institute for Microelectronics and Microsystems (CNR-IMM), Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Tuca, S.S.; Gramse, G. [Johannes Kepler University, Institute for Biophysics, Gruberstrasse 40, A-4020 Linz (Austria); Lucibello, A.; Proietti, E. [National Research Council, Institute for Microelectronics and Microsystems (CNR-IMM), Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Kienberger, F. [Keysight Technologies Austria GmbH, Keysight Laboratories, Gruberstrasse 40, A-4020 Linz (Austria); Marcelli, R. [National Research Council, Institute for Microelectronics and Microsystems (CNR-IMM), Via del Fosso del Cavaliere 100, 00133 Rome (Italy)

2016-12-15

In this work, microwave characterization of magnetic materials using the scanning microwave microscopy (SMM) technique is presented. The capabilities of the SMM are employed for analyzing and imaging local magnetic properties of the materials under test at the nanoscale. The analyses are performed by acquiring both amplitude and phase of the reflected microwave signal. The changes in the reflection coefficient S{sub 11} are related to the local properties of the material under investigation, and the changes in its magnetic properties have been studied as a function of an external DC magnetic bias. Yttrium iron garnet (YIG) films deposited by RF sputtering and grown by liquid phase epitaxial (LPE) on gadolinium gallium garnet (GGG) substrates and permalloy samples have been characterized. An equivalent electromagnetic transmission line model is discussed for the quantitative analysis of the local magnetic properties. We also observed the hysteretic behavior of the reflection coefficient S{sub 11} with an external bias field. The imaging and spectroscopy analysis on the experimental results are evidently indicating the possibilities of measuring local changes in the intrinsic magnetic properties on the surface of the material.

Nanoscale surface modification of Li-rich layered oxides for high-capacity cathodes in Li-ion batteries

Science.gov (United States)

Lan, Xiwei; Xin, Yue; Wang, Libin; Hu, Xianluo

2018-03-01

Li-rich layered oxides (LLOs) have been developed as a high-capacity cathode material for Li-ion batteries, but the structural complexity and unique initial charging behavior lead to several problems including large initial capacity loss, capacity and voltage fading, poor cyclability, and inferior rate capability. Since the surface conditions are critical to electrochemical performance and the drawbacks, nanoscale surface modification for improving LLO's properties is a general strategy. This review mainly summarizes the surface modification of LLOs and classifies them into three types of surface pre-treatment, surface gradient doping, and surface coating. Surface pre-treatment usually introduces removal of Li2O for lower irreversible capacity while surface doping is aimed to stabilize the structure during electrochemical cycling. Surface coating layers with different properties, protective layers to suppress the interface side reaction, coating layers related to structural transformation, and electronic/ionic conductive layers for better rate capability, can avoid the shortcomings of LLOs. In addition to surface modification for performance enhancement, other strategies can also be investigated to achieve high-performance LLO-based cathode materials.

Canopy Dynamics in Nanoscale Ionic Materials

KAUST Repository

Jespersen, Michael L.

2010-07-27

Nanoscale ionic materials (NIMS) are organic - inorganic hybrids in which a core nanostructure is functionalized with a covalently attached corona and an ionically tethered organic canopy. NIMS are engineered to be liquids under ambient conditions in the absence of solvent and are of interest for a variety of applications. We have used nuclear magnetic resonance (NMR) relaxation and pulse-field gradient (PFG) diffusion experiments to measure the canopy dynamics of NIMS prepared from 18-nm silica cores modified by an alkylsilane monolayer possessing terminal sulfonic acid functionality, paired with an amine-terminated ethylene oxide/propylene oxide block copolymer canopy. Carbon NMR studies show that the block copolymer canopy is mobile both in the bulk and in the NIMS and that the fast (ns) dynamics are insensitive to the presence of the silica nanoparticles. Canopy diffusion in the NIMS is slowed relative to the neat canopy, but not to the degree predicted from the diffusion of hard-sphere particles. Canopy diffusion is not restricted to the surface of the nanoparticles and shows unexpected behavior upon addition of excess canopy. Taken together, these data indicate that the liquid-like behavior in NIMS is due to rapid exchange of the block copolymer canopy between the ionically modified nanoparticles. © 2010 American Chemical Society.

Canopy Dynamics in Nanoscale Ionic Materials

KAUST Repository

Jespersen, Michael L.; Mirau, Peter A.; Meerwall, Ernst von; Vaia, Richard A.; Rodriguez, Robert; Giannelis, Emmanuel P.

2010-01-01

Nanoscale ionic materials (NIMS) are organic - inorganic hybrids in which a core nanostructure is functionalized with a covalently attached corona and an ionically tethered organic canopy. NIMS are engineered to be liquids under ambient conditions in the absence of solvent and are of interest for a variety of applications. We have used nuclear magnetic resonance (NMR) relaxation and pulse-field gradient (PFG) diffusion experiments to measure the canopy dynamics of NIMS prepared from 18-nm silica cores modified by an alkylsilane monolayer possessing terminal sulfonic acid functionality, paired with an amine-terminated ethylene oxide/propylene oxide block copolymer canopy. Carbon NMR studies show that the block copolymer canopy is mobile both in the bulk and in the NIMS and that the fast (ns) dynamics are insensitive to the presence of the silica nanoparticles. Canopy diffusion in the NIMS is slowed relative to the neat canopy, but not to the degree predicted from the diffusion of hard-sphere particles. Canopy diffusion is not restricted to the surface of the nanoparticles and shows unexpected behavior upon addition of excess canopy. Taken together, these data indicate that the liquid-like behavior in NIMS is due to rapid exchange of the block copolymer canopy between the ionically modified nanoparticles. © 2010 American Chemical Society.

Boiling and quenching heat transfer advancement by nanoscale surface modification.

Science.gov (United States)

Hu, Hong; Xu, Cheng; Zhao, Yang; Ziegler, Kirk J; Chung, J N

2017-07-21

All power production, refrigeration, and advanced electronic systems depend on efficient heat transfer mechanisms for achieving high power density and best system efficiency. Breakthrough advancement in boiling and quenching phase-change heat transfer processes by nanoscale surface texturing can lead to higher energy transfer efficiencies, substantial energy savings, and global reduction in greenhouse gas emissions. This paper reports breakthrough advancements on both fronts of boiling and quenching. The critical heat flux (CHF) in boiling and the Leidenfrost point temperature (LPT) in quenching are the bottlenecks to the heat transfer advancements. As compared to a conventional aluminum surface, the current research reports a substantial enhancement of the CHF by 112% and an increase of the LPT by 40 K using an aluminum surface with anodized aluminum oxide (AAO) nanoporous texture finish. These heat transfer enhancements imply that the power density would increase by more than 100% and the quenching efficiency would be raised by 33%. A theory that links the nucleation potential of the surface to heat transfer rates has been developed and it successfully explains the current finding by revealing that the heat transfer modification and enhancement are mainly attributed to the superhydrophilic surface property and excessive nanoscale nucleation sites created by the nanoporous surface.

Report of the 2nd RCM on nanoscale radiation engineering of advanced materials for potential biomedical applications

International Nuclear Information System (INIS)

2010-01-01

There are critical needs for advanced materials in the area of biomaterial engineering, primarily in generating biomaterials of enhanced specific functionalities, improved biocompatibility, and minimal natural rejection but with enhanced interfacial adhesion. These can be achieved by introduction of proper functionalities at the nanoscale dimensions for which, due to their characteristics, radiation techniques are uniquely suited. Accordingly, many of the IAEA Member States (MS) have interest in creating advanced materials for various health-care applications using a wide array of radiation sources and their broad expertise. In seeking new knowledge to advance the field and tackle this specific problem, to collaborate to enhance the quality of the scientific research and improve their efficiency and effectiveness, MS had requested the support of the IAEA for such collaboration. Based on these requests, and the conclusions and recommendations of the Consultant's meeting on Advanced Materials on the Nano-scale Synthesized by Radiation-Induced Processes, held on 10-14 December 2007, the present CRP was formulated and started in 2009. The first RCM was held in 30 March – 3 April 2009, in Vienna, where the work plan for both individual participants and collaborations were discussed and accepted, as reported in the Meeting Report published as IAEA Working Material (http://www-naweb.iaea.org/napc/iachem/working_materials.html). The second RCM was held on 15-19 November 2010, Paris, France, and was attended by 17 participants (chief scientific investigators or team members) and one cost-free observer from Brazil. The participants presented their research achievements since the first RCM, centred on the main expected outputs of this CRP: a. Methodologies to prepare and characterize nanogels; nanoparticles and nanoporous membranes, as well as to synthesize and modify nanoparticle surfaces by attaching organic ligands by radiation; b. Methodologies to radiation synthesize

Nanoscale protein arrays of rich morphologies via self-assembly on chemically treated diblock copolymer surfaces

International Nuclear Information System (INIS)

Song Sheng; Milchak, Marissa; Zhou Hebing; Lee, Thomas; Hanscom, Mark; Hahm, Jong-in

2013-01-01

Well-controlled assembly of proteins on supramolecular templates of block copolymers can be extremely useful for high-throughput biodetection. We report the adsorption and assembly characteristics of a model antibody protein to various polystyrene-block-poly(4-vinylpyridine) templates whose distinctive nanoscale structures are obtained through time-regulated exposure to chloroform vapor. The strong adsorption preference of the protein to the polystyrene segment in the diblock copolymer templates leads to an easily predictable, controllable, rich set of nanoscale protein morphologies through self-assembly. We also demonstrate that the chemical identities of various subareas within individual nanostructures can be readily elucidated by investigating the corresponding protein adsorption behavior on each chemically distinct area of the template. In our approach, a rich set of intricate nanoscale morphologies of protein arrays that cannot be easily attained through other means can be generated straightforwardly via self-assembly of proteins on chemically treated diblock copolymer surfaces, without the use of clean-room-based fabrication tools. Our approach provides much-needed flexibility and versatility for the use of block copolymer-based protein arrays in biodetection. The ease of fabrication in producing well-defined and self-assembled templates can contribute to a high degree of versatility and simplicity in acquiring an intricate nanoscale geometry and spatial distribution of proteins in arrays. These advantages can be extremely beneficial both for fundamental research and biomedical detection, especially in the areas of solid-state-based, high-throughput protein sensing. (paper)

Rocket Science at the Nanoscale.

Science.gov (United States)

Li, Jinxing; Rozen, Isaac; Wang, Joseph

2016-06-28

Autonomous propulsion at the nanoscale represents one of the most challenging and demanding goals in nanotechnology. Over the past decade, numerous important advances in nanotechnology and material science have contributed to the creation of powerful self-propelled micro/nanomotors. In particular, micro- and nanoscale rockets (MNRs) offer impressive capabilities, including remarkable speeds, large cargo-towing forces, precise motion controls, and dynamic self-assembly, which have paved the way for designing multifunctional and intelligent nanoscale machines. These multipurpose nanoscale shuttles can propel and function in complex real-life media, actively transporting and releasing therapeutic payloads and remediation agents for diverse biomedical and environmental applications. This review discusses the challenges of designing efficient MNRs and presents an overview of their propulsion behavior, fabrication methods, potential rocket fuels, navigation strategies, practical applications, and the future prospects of rocket science and technology at the nanoscale.

Achieving atomistic control in materials processing by plasma–surface interactions

International Nuclear Information System (INIS)

Chang, Jeffrey; Chang, Jane P

2017-01-01

The continuous down-scaling of electronic devices and the introduction of functionally improved novel materials require a greater atomic level controllability in the synthesis and patterning of thin film materials, especially with regards to deposition uniformity and conformality as well as etching selectivity and anisotropy. The richness of plasma chemistry and the corresponding plasma–surface interactions provide the much needed processing flexibility and efficacy. To achieve the integration of the novel materials into devices, plasma-enhanced atomic layer processing techniques are emerging as the enabling factors to obtain atomic scale control of complex materials and nanostructures. This review focuses on an overview of the role of respective plasma species involved in plasma–surface interactions, addressing their respective and synergistic effects, which is followed by two distinct applications: plasma-enhanced atomic layer deposition (ALD) and atomic layer etching (ALE). For plasma-enhanced ALD, this review emphasizes the use of plasma chemistry to enable alternative pathways to synthesize complex materials at low temperatures and the challenges associated with deposition conformality. For plasma enabled ALE processes, the review focuses on the surface-specific chemical reactions needed to achieve desirable selectivity and anisotropy. (topical review)

Controlling high-throughput manufacturing at the nano-scale

Science.gov (United States)

Cooper, Khershed P.

2013-09-01

Interest in nano-scale manufacturing research and development is growing. The reason is to accelerate the translation of discoveries and inventions of nanoscience and nanotechnology into products that would benefit industry, economy and society. Ongoing research in nanomanufacturing is focused primarily on developing novel nanofabrication techniques for a variety of applications—materials, energy, electronics, photonics, biomedical, etc. Our goal is to foster the development of high-throughput methods of fabricating nano-enabled products. Large-area parallel processing and highspeed continuous processing are high-throughput means for mass production. An example of large-area processing is step-and-repeat nanoimprinting, by which nanostructures are reproduced again and again over a large area, such as a 12 in wafer. Roll-to-roll processing is an example of continuous processing, by which it is possible to print and imprint multi-level nanostructures and nanodevices on a moving flexible substrate. The big pay-off is high-volume production and low unit cost. However, the anticipated cost benefits can only be realized if the increased production rate is accompanied by high yields of high quality products. To ensure product quality, we need to design and construct manufacturing systems such that the processes can be closely monitored and controlled. One approach is to bring cyber-physical systems (CPS) concepts to nanomanufacturing. CPS involves the control of a physical system such as manufacturing through modeling, computation, communication and control. Such a closely coupled system will involve in-situ metrology and closed-loop control of the physical processes guided by physics-based models and driven by appropriate instrumentation, sensing and actuation. This paper will discuss these ideas in the context of controlling high-throughput manufacturing at the nano-scale.

EXAFS and XANES analysis of oxides at the nanoscale

Directory of Open Access Journals (Sweden)

Alexei Kuzmin

2014-11-01

Full Text Available Worldwide research activity at the nanoscale is triggering the appearance of new, and frequently surprising, materials properties in which the increasing importance of surface and interface effects plays a fundamental role. This opens further possibilities in the development of new multifunctional materials with tuned physical properties that do not arise together at the bulk scale. Unfortunately, the standard methods currently available for solving the atomic structure of bulk crystals fail for nanomaterials due to nanoscale effects (very small crystallite sizes, large surface-to-volume ratio, near-surface relaxation, local lattice distortions etc.. As a consequence, a critical reexamination of the available local-structure characterization methods is needed. This work discusses the real possibilities and limits of X-ray absorption spectroscopy (XAS analysis at the nanoscale. To this end, the present state of the art for the interpretation of extended X-ray absorption fine structure (EXAFS is described, including an advanced approach based on the use of classical molecular dynamics and its application to nickel oxide nanoparticles. The limits and possibilities of X-ray absorption near-edge spectroscopy (XANES to determine several effects associated with the nanocrystalline nature of materials are discussed in connection with the development of ZnO-based dilute magnetic semiconductors (DMSs and iron oxide nanoparticles.

Hierarchical Canopy Dynamics of Electrolyte-Doped Nanoscale Ionic Materials

KAUST Repository

Jespersen, Michael L.

2013-12-23

Nanoscale ionic materials (NIMs) are organic-inorganic hybrids prepared from ionically functionalized nanoparticles (NP) neutralized by oligomeric polymer counterions. NIMs are designed to behave as liquids under ambient conditions in the absence of solvent and have no volatile organic content, making them useful for a number of applications. We have used nuclear magnetic resonance relaxation and pulsed-field gradient NMR to probe local and collective canopy dynamics in NIMs based on 18-nm silica NPs with a covalently bound anionic corona, neutralized by amine-terminated ethylene oxide/propylene oxide block copolymers. The NMR relaxation studies show that the nanosecond-scale canopy dynamics depend on the degree of neutralization, the canopy radius of gyration, and crowding at the ionically modified NP surface. Two canopy populations are observed in the diffusion experiments, demonstrating that one fraction of the canopy is bound to the NP surface on the time scale (milliseconds) of the diffusion experiment and is surrounded by a more mobile layer of canopy that is unable to access the surface due to molecular crowding. The introduction of electrolyte ions (Na+ or Mg2+) screens the canopy-corona electrostatic interactions, resulting in a reduced bulk viscosity and faster canopy exchange. The magnitude of the screening effect depends upon ion concentration and valence, providing a simple route for tuning the macroscopic properties of NIMs. © 2013 American Chemical Society.

Hierarchical Canopy Dynamics of Electrolyte-Doped Nanoscale Ionic Materials

KAUST Repository

Jespersen, Michael L.; Mirau, Peter A.; von Meerwall, Ernst D.; Koerner, Hilmar; Vaia, Richard A.; Fernandes, Nikhil J.; Giannelis, Emmanuel P.

2013-01-01

Nanoscale ionic materials (NIMs) are organic-inorganic hybrids prepared from ionically functionalized nanoparticles (NP) neutralized by oligomeric polymer counterions. NIMs are designed to behave as liquids under ambient conditions in the absence of solvent and have no volatile organic content, making them useful for a number of applications. We have used nuclear magnetic resonance relaxation and pulsed-field gradient NMR to probe local and collective canopy dynamics in NIMs based on 18-nm silica NPs with a covalently bound anionic corona, neutralized by amine-terminated ethylene oxide/propylene oxide block copolymers. The NMR relaxation studies show that the nanosecond-scale canopy dynamics depend on the degree of neutralization, the canopy radius of gyration, and crowding at the ionically modified NP surface. Two canopy populations are observed in the diffusion experiments, demonstrating that one fraction of the canopy is bound to the NP surface on the time scale (milliseconds) of the diffusion experiment and is surrounded by a more mobile layer of canopy that is unable to access the surface due to molecular crowding. The introduction of electrolyte ions (Na+ or Mg2+) screens the canopy-corona electrostatic interactions, resulting in a reduced bulk viscosity and faster canopy exchange. The magnitude of the screening effect depends upon ion concentration and valence, providing a simple route for tuning the macroscopic properties of NIMs. © 2013 American Chemical Society.

Investigation of graphene-based nanoscale radiation sensitive materials

Science.gov (United States)

Robinson, Joshua A.; Wetherington, Maxwell; Hughes, Zachary; LaBella, Michael, III; Bresnehan, Michael

2012-06-01

Current state-of-the-art nanotechnology offers multiple benefits for radiation sensing applications. These include the ability to incorporate nano-sized radiation indicators into widely used materials such as paint, corrosion-resistant coatings, and ceramics to create nano-composite materials that can be widely used in everyday life. Additionally, nanotechnology may lead to the development of ultra-low power, flexible detection systems that can be embedded in clothing or other systems. Graphene, a single layer of graphite, exhibits exceptional electronic and structural properties, and is being investigated for high-frequency devices and sensors. Previous work indicates that graphene-oxide (GO) - a derivative of graphene - exhibits luminescent properties that can be tailored based on chemistry; however, exploration of graphene-oxide's ability to provide a sufficient change in luminescent properties when exposed to gamma or neutron radiation has not been carried out. We investigate the mechanisms of radiation-induced chemical modifications and radiation damage induced shifts in luminescence in graphene-oxide materials to provide a fundamental foundation for further development of radiation sensitive detection architectures. Additionally, we investigate the integration of hexagonal boron nitride (hBN) with graphene-based devices to evaluate radiation induced conductivity in nanoscale devices. Importantly, we demonstrate the sensitivity of graphene transport properties to the presence of alpha particles, and discuss the successful integration of hBN with large area graphene electrodes as a means to provide the foundation for large-area nanoscale radiation sensors.

Report of the 2nd RCM on nanoscale radiation engineering of advanced materials for potential biomedical applications

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-07-01

There are critical needs for advanced materials in the area of biomaterial engineering, primarily in generating biomaterials of enhanced specific functionalities, improved biocompatibility, and minimal natural rejection but with enhanced interfacial adhesion. These can be achieved by introduction of proper functionalities at the nanoscale dimensions for which, due to their characteristics, radiation techniques are uniquely suited. Accordingly, many of the IAEA Member States (MS) have interest in creating advanced materials for various health-care applications using a wide array of radiation sources and their broad expertise. In seeking new knowledge to advance the field and tackle this specific problem, to collaborate to enhance the quality of the scientific research and improve their efficiency and effectiveness, MS had requested the support of the IAEA for such collaboration. Based on these requests, and the conclusions and recommendations of the Consultant's meeting on Advanced Materials on the Nano-scale Synthesized by Radiation-Induced Processes, held on 10-14 December 2007, the present CRP was formulated and started in 2009. The first RCM was held in 30 March – 3 April 2009, in Vienna, where the work plan for both individual participants and collaborations were discussed and accepted, as reported in the Meeting Report published as IAEA Working Material (http://www-naweb.iaea.org/napc/iachem/working{sub m}aterials.html). The second RCM was held on 15-19 November 2010, Paris, France, and was attended by 17 participants (chief scientific investigators or team members) and one cost-free observer from Brazil. The participants presented their research achievements since the first RCM, centred on the main expected outputs of this CRP: a. Methodologies to prepare and characterize nanogels; nanoparticles and nanoporous membranes, as well as to synthesize and modify nanoparticle surfaces by attaching organic ligands by radiation; b. Methodologies to radiation

Surface roughness control by extreme ultraviolet (EUV) radiation

Science.gov (United States)

Ahad, Inam Ul; Obeidi, Muhannad Ahmed; Budner, Bogusław; Bartnik, Andrzej; Fiedorowicz, Henryk; Brabazon, Dermot

2017-10-01

Surface roughness control of polymeric materials is often desirable in various biomedical engineering applications related to biocompatibility control, separation science and surface wettability control. In this study, Polyethylene terephthalate (PET) polymer films were irradiated with Extreme ultraviolet (EUV) photons in nitrogen environment and investigations were performed on surface roughness modification via EUV exposure. The samples were irradiated at 3 mm and 4 mm distance from the focal spot to investigate the effect of EUV fluence on topography. The topography of the EUV treated PET samples were studied by AFM. The detailed scanning was also performed on the sample irradiated at 3 mm. It was observed that the average surface roughness of PET samples was increased from 9 nm (pristine sample) to 280 nm and 253 nm for EUV irradiated samples. Detailed AFM studies confirmed the presence of 1.8 mm wide period U-shaped channels in EUV exposed PET samples. The walls of the channels were having FWHM of about 0.4 mm. The channels were created due to translatory movements of the sample in horizontal and transverse directions during the EUV exposure. The increased surface roughness is useful for many applications. The nanoscale channels fabricated by EUV exposure could be interesting for microfluidic applications based on lab-on-a-chip (LOC) devices.

Dynamic structural disorder in supported nanoscale catalysts

International Nuclear Information System (INIS)

Rehr, J. J.; Vila, F. D.

2014-01-01

We investigate the origin and physical effects of “dynamic structural disorder” (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale

Dynamic structural disorder in supported nanoscale catalysts

Energy Technology Data Exchange (ETDEWEB)

Rehr, J. J.; Vila, F. D. [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)

2014-04-07

We investigate the origin and physical effects of “dynamic structural disorder” (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale.

A nanoscale ordered materials diffractometer for the SNS

International Nuclear Information System (INIS)

Neuefeind, Joerg; Chipley, Kenneth K.; Tulk, Chris A.; Simonson, J. Michael; Winokur, Michael J.

2006-01-01

The Nanoscale Ordered Materials Diffractometer (NOMAD) is one of five neutron scattering instruments being managed within the Spallation Neutron Source (SNS) Instruments-Next Generation (SING) project. NOMAD is designed as a high-flux, medium-resolution diffractometer using a large bandwidth of neutron energies and extensive detector coverage to perform structural determinations of local order in crystalline and amorphous materials. The instrument will enable studies of a large variety of samples ranging from liquids, solutions, glasses, polymers, and nanocrystalline materials to long-range ordered crystals and will allow unprecedented access to high-resolution pair distribution functions, small-contrast isotope substitution experiments, small sample sizes, and parametric studies. Project completion for the instrument is anticipated in 2010 and a review of the design status will be given

One-pot Synthesis of Soluble Nanoscale CIGS Photoactive Functional Materials

Directory of Open Access Journals (Sweden)

Yan Aixia

2007-01-01

Full Text Available Abstract Promising alternatives for solar energy utilization are thin film technologies involving various new materials. This contribution describes an easy and inexpensive synthetic method that can be used to prepare soluble nanoscale triphenyl phosphine-coordinated CIGS (TPP-CIGS photoactive functional materials. This complex is stable in the solid state under the irradiation of the ambient light, but its solution becomes a little bit unstable under the illumination of the low intensity laser.

Molecular and nanoscale materials and devices in electronics.

Science.gov (United States)

Fu, Lei; Cao, Lingchao; Liu, Yunqi; Zhu, Daoben

2004-12-13

Over the past several years, there have been many significant advances toward the realization of electronic computers integrated on the molecular scale and a much greater understanding of the types of materials that will be useful in molecular devices and their properties. It was demonstrated that individual molecules could serve as incomprehensibly tiny switch and wire one million times smaller than those on conventional silicon microchip. This has resulted very recently in the assembly and demonstration of tiny computer logic circuits built from such molecular scale devices. The purpose of this review is to provide a general introduction to molecular and nanoscale materials and devices in electronics.

Molecular dynamics investigation of nanoscale substrate topography and its interaction with liquids

Science.gov (United States)

Cordeiro Rodrigues, Jhonatam

Nanotechnology has been presenting successful applications in several areas. However, experimentation with nanoscale materials is costly and limited in analysis capability. This research investigates the use of molecular dynamics (MD) simulations to model and study nanomaterials and manufacturing processes. MD simulations are employed to reduce cost, optimize design, increase productivity and allow for the investigation of material interactions not yet observable through experimentation. This work investigates the interaction of water with substrates at the nanoscale. The effect of temperature, droplet impingement velocities and size, as well as substrate material, are investigated at the nanoscale. Several substrate topography designs were modeled to reveal their influence on the wettability of the substrate. Nanoscale gold and silicon substrates are more hydrophilic at higher temperatures than at room temperature. The reduction in droplet diameter increases its wettability. High impingement velocity of droplets does not influence final wettability of substrates but induces higher diffusion rates of droplets in a heated environment. Droplets deposited over a gradient of surface exposure presents spontaneous movement. The Leidenfrost effect was investigated at the nanoscale. Droplets of 4 and 10nm in diameter presented behaviors pertinent to the Leidenfrost effect at 373K, significantly lower than at micro scale and of potential impact to the field. Topographical features were manipulated using superhydrophobic coating resulting in micro whiskers. Nanoimprint lithography (NIL) was used to manufacture substrate topographies at the nanoscale. Water droplets were deposited on the substrates and their wettability was measured using droplet contact angles. Lower surface area exposure resulted in higher contact angles. The experimental relationships between surface topography and substrate wettability were used to validate the insights gained from MD simulations for

Atomic layer deposition: an enabling technology for the growth of functional nanoscale semiconductors

Science.gov (United States)

Biyikli, Necmi; Haider, Ali

2017-09-01

In this paper, we present the progress in the growth of nanoscale semiconductors grown via atomic layer deposition (ALD). After the adoption by semiconductor chip industry, ALD became a widespread tool to grow functional films and conformal ultra-thin coatings for various applications. Based on self-limiting and ligand-exchange-based surface reactions, ALD enabled the low-temperature growth of nanoscale dielectric, metal, and semiconductor materials. Being able to deposit wafer-scale uniform semiconductor films at relatively low-temperatures, with sub-monolayer thickness control and ultimate conformality, makes ALD attractive for semiconductor device applications. Towards this end, precursors and low-temperature growth recipes are developed to deposit crystalline thin films for compound and elemental semiconductors. Conventional thermal ALD as well as plasma-assisted and radical-enhanced techniques have been exploited to achieve device-compatible film quality. Metal-oxides, III-nitrides, sulfides, and selenides are among the most popular semiconductor material families studied via ALD technology. Besides thin films, ALD can grow nanostructured semiconductors as well using either template-assisted growth methods or bottom-up controlled nucleation mechanisms. Among the demonstrated semiconductor nanostructures are nanoparticles, nano/quantum-dots, nanowires, nanotubes, nanofibers, nanopillars, hollow and core-shell versions of the afore-mentioned nanostructures, and 2D materials including transition metal dichalcogenides and graphene. ALD-grown nanoscale semiconductor materials find applications in a vast amount of applications including functional coatings, catalysis and photocatalysis, renewable energy conversion and storage, chemical sensing, opto-electronics, and flexible electronics. In this review, we give an overview of the current state-of-the-art in ALD-based nanoscale semiconductor research including the already demonstrated and future applications.

Controlled heat flux measurement across a closing nanoscale gap and its comparison to theory

Energy Technology Data Exchange (ETDEWEB)

Ma, Y.; Ghafari, A.; Budaev, B. V.; Bogy, D. B., E-mail: dbogy@berkeley.edu [Department of mechanical Engineering, Computer Mechanics Lab, University of California, Berkeley, California 94720 (United States)

2016-05-23

We present here a controlled measurement of heat flux across a closing gap that is initially less than 10 nm wide between two solid surfaces at different temperatures. The measured heat transfer is compared with our published theoretical analyses of this phenomenon that show thermal radiation dominates the heat transfer for gaps wider than about 1–2 nm, but phonon conduction dominates between 1 and 2 nm and contact. The experiments employ a thermal actuator mounted on a rocking base block for coarse positioning that supplies Joule heating to an embedded element to cause thermal expansion of a localized region for less than 10 nm spacing control, together with an embedded near-surface resistive temperature sensor to measure its temperature change due to the heat flux across the gap. The measured results are in general agreement with the theoretical predictions, and they also agree with common sense expectations. This paper not only shows nano-scale heat transfer measurement across a closing gap, it also lends additional strong support to the validity of the referenced theoretical developments. The proposed experimental approach can provide support to design of future devices for nano-scale heat transfer measurement.

Friction and Surface Dynamics of Polymers on the Nanoscale by AFM

NARCIS (Netherlands)

Schönherr, Holger; Schónherr, Holger; Samori, Paolo; Tocha, E.; Vancso, Gyula J.

2008-01-01

In this article the measurement and understanding of friction forces and surface dynamics of polymers on the one hand and the importance of molecular relaxation processes and viscoelasticity in polymers for advanced micro- and nanoscale applications on the other hand are discussed. Particular

Measurements of stiff-material compliance on the nanoscale using ultrasonic force microscopy

Science.gov (United States)

Dinelli, F.; Biswas, S. K.; Briggs, G. A. D.; Kolosov, O. V.

2000-05-01

Ultrasonic force microscopy (UFM) was introduced to probe nanoscale mechanical properties of stiff materials. This was achieved by vibrating the sample far above the first resonance of the probing atomic force microscope cantilever where the cantilever becomes dynamically rigid. By operating UFM at different set force values, it is possible to directly measure the absolute values of the tip-surface contact stiffness. From this an evaluation of surface elastic properties can be carried out assuming a suitable solid-solid contact model. In this paper we present curves of stiffness as a function of the normal load in the range of 0-300 nN. The dependence of stiffness on the relative humidity has also been investigated. Materials with different elastic constants (such as sapphire lithium fluoride, and silicon) have been successfully differentiated. Continuum mechanics models cannot however explain the dependence of stiffness on the normal force and on the relative humidity. In this high-frequency regime, it is likely that viscous forces might play an important role modifying the tip-surface interaction. Plastic deformation might also occur due to the high strain rates applied when ultrasonically vibrating the sample. Another possible cause of these discrepancies might be the presence of water in between the two bodies in contact organizing in a solidlike way and partially sustaining the load.

Controlling the Nanoscale Patterning of AuNPs on Silicon Surfaces

Directory of Open Access Journals (Sweden)

Chris J. Allender

2013-03-01

Full Text Available This study evaluates the effectiveness of vapour-phase deposition for creating sub-monolayer coverage of aminopropyl triethoxysilane (APTES on silicon in order to exert control over subsequent gold nanoparticle deposition. Surface coverage was evaluated indirectly by observing the extent to which gold nanoparticles (AuNPs deposited onto the modified silicon surface. By varying the distance of the silicon wafer from the APTES source and concentration of APTES in the evaporating media, control over subsequent gold nanoparticle deposition was achievable to an extent. Fine control over AuNP deposition (AuNPs/μm2 however, was best achieved by adjusting the ionic concentration of the AuNP-depositing solution. Furthermore it was demonstrated that although APTES was fully removed from the silicon surface following four hours incubation in water, the gold nanoparticle-amino surface complex was stable under the same conditions. Atomic force microscopy (AFM and X-ray photoelectron spectroscopy (XPS were used to study these affects.

Curcumin induced nanoscale CD44 molecular redistribution and antigen-antibody interaction on HepG2 cell surface

Energy Technology Data Exchange (ETDEWEB)

Wang Mu [Department of Chemistry, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China); Ruan Yuxia [Department of Ophthalmology, The First Affiliated Hospital, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China); Xing Xiaobo; Chen Qian; Peng, Yuan [Department of Chemistry, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China); Cai Jiye, E-mail: tjycai@jnu.edu.cn [Department of Chemistry, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China)

2011-07-04

Graphical abstract: Highlights: > In this study, we investigate the changes of CD44 expression and distribution on HepG2 cells after curcumin treatment. > We find curcumin is able to change the morphology and ultrastructure of HepG2 cells. > Curcumin can reduce the expression of CD44 molecules and induce the nanoscale molecular redistribution on cell surface. > The binding force between CD44-modified AFM tip and the HepG2 cell surface decreases after curcumin-treatment. - Abstract: The cell surface glycoprotein CD44 was implicated in the progression, metastasis and apoptosis of certain human tumors. In this study, we used atomic force microscope (AFM) to monitor the effect of curcumin on human hepatocellular carcinoma (HepG2) cell surface nanoscale structure. High-resolution imaging revealed that cell morphology and ultrastructure changed a lot after being treated with curcumin. The membrane average roughness increased (10.88 {+-} 4.62 nm to 129.70 {+-} 43.72 nm) and the expression of CD44 decreased (99.79 {+-} 0.16% to 75.14 {+-} 8.37%). Laser scanning confocal microscope (LSCM) imaging showed that CD44 molecules were located on the cell membrane. The florescence intensity in control group was weaker than that in curcumin treated cells. Most of the binding forces between CD44 antibodies and untreated HepG2 cell membrane were around 120-220 pN. After being incubated with curcumin, the major forces focused on 70-150 pN (10 {mu}M curcumin-treated) and 50-120 pN (20 {mu}M curcumin-treated). These results suggested that, as result of nanoscale molecular redistribution, changes of the cell surface were in response to external treatment of curcumin. The combination of AFM and LSCM could be a powerful method to detect the distribution of cell surface molecules and interactions between molecules and their ligands.

Curcumin induced nanoscale CD44 molecular redistribution and antigen-antibody interaction on HepG2 cell surface

International Nuclear Information System (INIS)

Wang Mu; Ruan Yuxia; Xing Xiaobo; Chen Qian; Peng, Yuan; Cai Jiye

2011-01-01

Graphical abstract: Highlights: → In this study, we investigate the changes of CD44 expression and distribution on HepG2 cells after curcumin treatment. → We find curcumin is able to change the morphology and ultrastructure of HepG2 cells. → Curcumin can reduce the expression of CD44 molecules and induce the nanoscale molecular redistribution on cell surface. → The binding force between CD44-modified AFM tip and the HepG2 cell surface decreases after curcumin-treatment. - Abstract: The cell surface glycoprotein CD44 was implicated in the progression, metastasis and apoptosis of certain human tumors. In this study, we used atomic force microscope (AFM) to monitor the effect of curcumin on human hepatocellular carcinoma (HepG2) cell surface nanoscale structure. High-resolution imaging revealed that cell morphology and ultrastructure changed a lot after being treated with curcumin. The membrane average roughness increased (10.88 ± 4.62 nm to 129.70 ± 43.72 nm) and the expression of CD44 decreased (99.79 ± 0.16% to 75.14 ± 8.37%). Laser scanning confocal microscope (LSCM) imaging showed that CD44 molecules were located on the cell membrane. The florescence intensity in control group was weaker than that in curcumin treated cells. Most of the binding forces between CD44 antibodies and untreated HepG2 cell membrane were around 120-220 pN. After being incubated with curcumin, the major forces focused on 70-150 pN (10 μM curcumin-treated) and 50-120 pN (20 μM curcumin-treated). These results suggested that, as result of nanoscale molecular redistribution, changes of the cell surface were in response to external treatment of curcumin. The combination of AFM and LSCM could be a powerful method to detect the distribution of cell surface molecules and interactions between molecules and their ligands.

Nanoscale ferroelectrics and multiferroics key processes and characterization issues, and nanoscale effects

CERN Document Server

Alguero, Miguel

2016-01-01

This book reviews the key issues in processing and characterization of nanoscale ferroelectrics and multiferroics, and provides a comprehensive description of their properties, with an emphasis in differentiating size effects of extrinsic ones like boundary or interface effects. Recently described nanoscale novel phenomena are also addressed. Organized into three parts it addresses key issues in processing (nanostructuring), characterization (of the nanostructured materials) and nanoscale effects. Taking full advantage of the synergies between nanoscale ferroelectrics and multiferroics, it covers materials nanostructured at all levels, from ceramic technologies like ferroelectric nanopowders, bulk nanostructured ceramics and thick films, and magnetoelectric nanocomposites, to thin films, either polycrystalline layer heterostructures or epitaxial systems, and to nanoscale free standing objects with specific geometries, such as nanowires and tubes at different levels of development. The book is developed from t...

Expressions of the radius and the surface tension of surface of tension in terms of the pressure distribution for nanoscale liquid threads

International Nuclear Information System (INIS)

Yan Hong; Wei Jiu-An; Cui Shu-Wen; Zhu Ru-Zeng

2013-01-01

The expressions of the radius and the surface tension of surface of tension R s and γ s in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics (MD) simulations of the interfacial phenomena of nanoscale fluids; these two basic expressions are derived in this paper. Although these expressions were derived first in the literature [Kim B G, Lee J S, Han M H, and Park S, 2006 Nanoscale and Microscale Thermophysical Engineering, 10, 283] and used widely thereafter, the derivation is wrong both in logical structure and physical thought. In view of the importance of these basic expressions, the logic and physical mistakes appearing in that derivation are pointed out. (condensed matter: structural, mechanical, and thermal properties)

Numerical analysis of micro-/nanoscale gas-film lubrication of sliding surface with complicated structure

International Nuclear Information System (INIS)

Kawagoe, Yoshiaki; Isono, Susumu; Takeno, Takanori; Yonemura, Shigeru; Takagi, Toshiyuki; Miki, Hiroyuki

2014-01-01

It has been reported that the friction between a partially polished diamond-coated surface and a metal surface was drastically reduced to zero when they are slid at a few m/s. Since the sliding was noiseless, it seems that the diamond-coated surface was levitated over the counter surface and the sliding mechanism was the gas film lubrication. Recently, the mechanism of levitation of a slider with a micro/nanoscale surface structure on a rotating disk was theoretically clarified [S. Yonemura et al., Tribol. Lett., (2014), doi:10.1007/s11249-014-0368-2]. Probably, the partially polished diamond-coated surface may be levitated by high gas pressure generated by the micro/nanoscale surface structure on it. In this study, in order to verify our deduction, we performed numerical simulations of sliding of partially polished diamond-coated surface by reproducing its complicated surface structure using the data measured by an atomic force microscope (AFM). As a result, we obtained the lift force which is large enough to levitate the slider used in the experiment

Numerical analysis of micro-/nanoscale gas-film lubrication of sliding surface with complicated structure

Energy Technology Data Exchange (ETDEWEB)

Kawagoe, Yoshiaki; Isono, Susumu; Takeno, Takanori [Department of Nanomechanics, Graduate School of Engineering, Tohoku University, 6-6-01 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Yonemura, Shigeru; Takagi, Toshiyuki [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Miki, Hiroyuki [Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578 (Japan)

2014-12-09

It has been reported that the friction between a partially polished diamond-coated surface and a metal surface was drastically reduced to zero when they are slid at a few m/s. Since the sliding was noiseless, it seems that the diamond-coated surface was levitated over the counter surface and the sliding mechanism was the gas film lubrication. Recently, the mechanism of levitation of a slider with a micro/nanoscale surface structure on a rotating disk was theoretically clarified [S. Yonemura et al., Tribol. Lett., (2014), doi:10.1007/s11249-014-0368-2]. Probably, the partially polished diamond-coated surface may be levitated by high gas pressure generated by the micro/nanoscale surface structure on it. In this study, in order to verify our deduction, we performed numerical simulations of sliding of partially polished diamond-coated surface by reproducing its complicated surface structure using the data measured by an atomic force microscope (AFM). As a result, we obtained the lift force which is large enough to levitate the slider used in the experiment.

Defect Characterization, Imaging, and Control in Wide-Bandgap Semiconductors and Devices

Science.gov (United States)

Brillson, L. J.; Foster, G. M.; Cox, J.; Ruane, W. T.; Jarjour, A. B.; Gao, H.; von Wenckstern, H.; Grundmann, M.; Wang, B.; Look, D. C.; Hyland, A.; Allen, M. W.

2018-03-01

Wide-bandgap semiconductors are now leading the way to new physical phenomena and device applications at nanoscale dimensions. The impact of defects on the electronic properties of these materials increases as their size decreases, motivating new techniques to characterize and begin to control these electronic states. Leading these advances have been the semiconductors ZnO, GaN, and related materials. This paper highlights the importance of native point defects in these semiconductors and describes how a complement of spatially localized surface science and spectroscopy techniques in three dimensions can characterize, image, and begin to control these electronic states at the nanoscale. A combination of characterization techniques including depth-resolved cathodoluminescence spectroscopy, surface photovoltage spectroscopy, and hyperspectral imaging can describe the nature and distribution of defects at interfaces at both bulk and nanoscale surfaces, their metal interfaces, and inside nanostructures themselves. These features as well as temperature and mechanical strain inside wide-bandgap device structures at the nanoscale can be measured even while these devices are operating. These advanced capabilities enable several new directions for describing defects at the nanoscale, showing how they contribute to device degradation, and guiding growth processes to control them.

Nanoscale defect architectures and their influence on material properties

Science.gov (United States)

Campbell, Branton

2006-10-01

Diffraction studies of long-range order often permit one to unambiguously determine the atomic structure of a crystalline material. Many interesting material properties, however, are dominated by nanoscale crystal defects that can't be characterized in this way. Fortunately, advances in x-ray detector technology, synchrotron x-ray source brightness, and computational power make it possible to apply new methods to old problems. Our research group uses multi-megapixel x-ray cameras to map out large contiguous volumes of reciprocal space, which can then be visually explored using graphics engines originally developed by the video-game industry. Here, I will highlight a few recent examples that include high-temperature superconductors, colossal magnetoresistors and piezoelectric materials.

Evaporation characteristics of a hydrophilic surface with micro-scale and/or nano-scale structures fabricated by sandblasting and aluminum anodization

International Nuclear Information System (INIS)

Kim, Hyungmo; Kim, Joonwon

2010-01-01

This paper presents the results of evaporation experiments using water droplets on aluminum sheets that were either smooth or had surface structures at the micro-scale, at the nano-scale or at both micro- and nano-scales (dual-scale). The smooth surface was a polished aluminum sheet; the surface with micro-scale structures was obtained by sandblasting; the surface with nano-scale structures was obtained using conventional aluminum anodization and the surface with dual-scale structures was prepared using sandblasting and anodization sequentially. The wetting properties and evaporation rates were measured for each surface. The evaporation rates were affected by their static and dynamic wetting properties. Evaporation on the surface with dual-scale structures was fastest and the evaporation rate was analyzed quantitatively.

Plant virus directed fabrication of nanoscale materials and devices

Science.gov (United States)

2015-03-26

Structural features within the internal and external PVN surfaces are amenable to either chemi- cal or genetic modifications for the display of novel moieties...structures: from nanoboomerangs to tetrapods. Nanoscale 7, 344–355. Eggen, R., Verver, J., Wellink, J., De Jong, A., Goldbach, R., van Kammen, A., 1989...in planta expression and for templates for synthetic biology applica- tions. New Phytol. 200, 16–26. Saunders, K., Sainsbury, F., Lomonossoff, G.P

Nanoscale electron transport at the surface of a topological insulator

Science.gov (United States)

Bauer, Sebastian; Bobisch, Christian A.

2016-04-01

The use of three-dimensional topological insulators for disruptive technologies critically depends on the dissipationless transport of electrons at the surface, because of the suppression of backscattering at defects. However, in real devices, defects are unavoidable and scattering at angles other than 180° is allowed for such materials. Until now, this has been studied indirectly by bulk measurements and by the analysis of the local density of states in close vicinity to defect sites. Here, we directly measure the nanoscale voltage drop caused by the scattering at step edges, which occurs if a lateral current flows along a three-dimensional topological insulator. The experiments were performed using scanning tunnelling potentiometry for thin Bi2Se3 films. So far, the observed voltage drops are small because of large contributions of the bulk to the electronic transport. However, for the use of ideal topological insulating thin films in devices, these contributions would play a significant role.

The mechanical properties modeling of nano-scale materials by molecular dynamics

NARCIS (Netherlands)

Yuan, C.; Driel, W.D. van; Poelma, R.; Zhang, G.Q.

2012-01-01

We propose a molecular modeling strategy which is capable of mod-eling the mechanical properties on nano-scale low-dielectric (low-k) materials. Such modeling strategy has been also validated by the bulking force of carbon nano tube (CNT). This modeling framework consists of model generation method,

Controlling the nanoscale morphology of organic films deposited by polyatomic ions

CERN Document Server

Hanley, L; Fuoco, E R; Ahu-Akin, F; Wijesundara, M B J; Li, Maozhen; Tikhonov, A; Schlossman, M

2003-01-01

Hyperthermal polyatomic ion beams can be used to fabricate thin film nanostructures with controlled morphology. Several experiments are described in which mass-selected and non-mass-selected polyatomic ion beams are used to create nanometer thick films with controlled surface and buried interface morphologies. Fluorocarbon and thiophenic films are grown on silicon wafers and/or polystyrene from 5 to 200 eV C sub 3 F sub 5 sup + or C sub 4 H sub 4 S sup + ions, respectively. X-ray photoelectron spectroscopy, atomic force microscopy, X-ray reflectivity, and scanning electron microscopy are utilized to analyze the morphology and chemistry of these films. Polyatomic ions are found to control film morphology on the nanoscale through variation of the incident ion energy, ion structure and/or substrate.

Molecular Clusters: Nanoscale Building Blocks for Solid-State Materials.

Science.gov (United States)

Pinkard, Andrew; Champsaur, Anouck M; Roy, Xavier

2018-04-17

spectroscopy, to ascertain features about the constituent superatomic building blocks, such as the charge of the cluster cores, by analysis of bond distances from the SCXRD data. The combination of atomic precision and intercluster interactions in these SACs produces novel collective properties, including tunable electrical transport, crystalline thermal conductivity, and ferromagnetism. In addition, we have developed a synthetic strategy to insert redox-active guests into the superstructure of SACs via single-crystal-to-single-crystal intercalation. This intercalation process allows us to tune the optical and electrical transport properties of the superatomic crystal host. These properties are explored using a host of techniques, including Raman spectroscopy, SQUID magnetometry, electrical transport measurements, electronic absorption spectroscopy, differential scanning calorimetry, and frequency-domain thermoreflectance. Superatomic crystals have proven to be both robust and tunable, representing a new method of materials design and architecture. This Account demonstrates how precisely controlling the structure and properties of nanoscale building blocks is key in developing the next generation of functional materials; several examples are discussed and detailed herein.

Super-Resolution Molecular and Functional Imaging of Nanoscale Architectures in Life and Materials Science

KAUST Repository

Habuchi, Satoshi

2014-06-12

Super-resolution (SR) fluorescence microscopy has been revolutionizing the way in which we investigate the structures, dynamics, and functions of a wide range of nanoscale systems. In this review, I describe the current state of various SR fluorescence microscopy techniques along with the latest developments of fluorophores and labeling for the SR microscopy. I discuss the applications of SR microscopy in the fields of life science and materials science with a special emphasis on quantitative molecular imaging and nanoscale functional imaging. These studies open new opportunities for unraveling the physical, chemical, and optical properties of a wide range of nanoscale architectures together with their nanostructures and will enable the development of new (bio-)nanotechnology.

Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

KAUST Repository

Andrew Lin, Kun-Yi

2014-11-11

© The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

KAUST Repository

Andrew Lin, Kun-Yi; Park, Youngjune; Petit, Camille; Park, Ah-Hyung Alissa

2014-01-01

© The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

Fungal nanoscale metal carbonates and production of electrochemical materials.

Science.gov (United States)

Li, Qianwei; Gadd, Geoffrey Michael

2017-09-01

Fungal biomineralization of carbonates results in metal removal from solution or immobilization within a solid matrix. Such a system provides a promising method for removal of toxic or valuable metals from solution, such as Co, Ni, and La, with some carbonates being of nanoscale dimensions. A fungal Mn carbonate biomineralization process can be applied for the synthesis of novel electrochemical materials. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Mechanism of the nanoscale localization of Ge quantum dot nucleation on focused ion beam templated Si(001) surfaces

International Nuclear Information System (INIS)

Portavoce, A; Kammler, M; Hull, R; Reuter, M C; Ross, F M

2006-01-01

We investigate the fundamental mechanism by which self-assembled Ge islands can be nucleated at specific sites on Si(001) using ultra-low-dose focused ion beam (FIB) pre-patterning. Island nucleation is controlled by a nanotopography that forms after the implantation of Ga ions during subsequent thermal annealing of the substrate. This nanotopography evolves during the annealing stage, changing from a nanoscale annular depression associated with each focused ion beam spot to a nanoscale pit, and eventually disappearing (planarizing). The correspondence of Ge quantum dot nucleation sites to the focused ion beam features requires a growth surface upon which the nanotopography is preserved. A further key observation is that the Ge wetting layer thickness is reduced in patterned regions, allowing the formation of islands on the templated regions without nucleation elsewhere. These results provide routes to the greatly enhanced design and control of quantum dot distributions and dimensions

Ion beam modification of biological materials in nanoscale

Science.gov (United States)

Yu, L. D.; Anuntalabhochai, S.

2012-07-01

Ion interaction with biological objects in nanoscale is a novel research area stemming from applications of low-energy ion beams in biotechnology and biomedicine. Although the ion beam applications in biotechnology and biomedicine have achieved great successes, many mechanisms remain unclear and many new applications are to be explored. We have carried out some research on exploring the mechanisms and new applications besides attaining ion beam induction of mutation breeding and gene transformation. In the studies on the mechanisms, we focused our investigations on the direct interaction in nanoscale between ions and biological living materials. Our research topics have included the low-energy ion range in DNA, low-energy ion or neutral beam bombardment effect on DNA topological form change and mutation, low-energy ion or neutral beam bombardment effect on the cell envelope and gene transformation, and molecular dynamics simulation of ultra-low-energy ion irradiation of DNA. In the exploration of new applications, we have started experiments on ion irradiation or bombardment, in the nanoscaled depth or area, of human cells for biomedical research. This paper introduces our experiments and reports interesting results.

Ion beam modification of biological materials in nanoscale

International Nuclear Information System (INIS)

Yu, L.D.; Anuntalabhochai, S.

2012-01-01

Ion interaction with biological objects in nanoscale is a novel research area stemming from applications of low-energy ion beams in biotechnology and biomedicine. Although the ion beam applications in biotechnology and biomedicine have achieved great successes, many mechanisms remain unclear and many new applications are to be explored. We have carried out some research on exploring the mechanisms and new applications besides attaining ion beam induction of mutation breeding and gene transformation. In the studies on the mechanisms, we focused our investigations on the direct interaction in nanoscale between ions and biological living materials. Our research topics have included the low-energy ion range in DNA, low-energy ion or neutral beam bombardment effect on DNA topological form change and mutation, low-energy ion or neutral beam bombardment effect on the cell envelope and gene transformation, and molecular dynamics simulation of ultra-low-energy ion irradiation of DNA. In the exploration of new applications, we have started experiments on ion irradiation or bombardment, in the nanoscaled depth or area, of human cells for biomedical research. This paper introduces our experiments and reports interesting results.

Nonplanar Nanoscale Fin Field Effect Transistors on Textile, Paper, Wood, Stone, and Vinyl via Soft Material-Enabled Double-Transfer Printing.

Science.gov (United States)

Rojas, Jhonathan P; Torres Sevilla, Galo A; Alfaraj, Nasir; Ghoneim, Mohamed T; Kutbee, Arwa T; Sridharan, Ashvitha; Hussain, Muhammad Mustafa

2015-05-26

The ability to incorporate rigid but high-performance nanoscale nonplanar complementary metal-oxide semiconductor (CMOS) electronics with curvilinear, irregular, or asymmetric shapes and surfaces is an arduous but timely challenge in enabling the production of wearable electronics with an in situ information-processing ability in the digital world. Therefore, we are demonstrating a soft-material enabled double-transfer-based process to integrate flexible, silicon-based, nanoscale, nonplanar, fin-shaped field effect transistors (FinFETs) and planar metal-oxide-semiconductor field effect transistors (MOSFETs) on various asymmetric surfaces to study their compatibility and enhanced applicability in various emerging fields. FinFET devices feature sub-20 nm dimensions and state-of-the-art, high-κ/metal gate stacks, showing no performance alteration after the transfer process. A further analysis of the transferred MOSFET devices, featuring 1 μm gate length, exhibits an ION value of nearly 70 μA/μm (VDS = 2 V, VGS = 2 V) and a low subthreshold swing of around 90 mV/dec, proving that a soft interfacial material can act both as a strong adhesion/interposing layer between devices and final substrate as well as a means to reduce strain, which ultimately helps maintain the device's performance with insignificant deterioration even at a high bending state.

Fast heat flux modulation at the nanoscale

OpenAIRE

van Zwol, P. J.; Joulain, K.; Abdallah, P. Ben; Greffet, J. J.; Chevrier, J.

2011-01-01

We introduce a new concept for electrically controlled heat flux modulation. A flux contrast larger than 10 dB is expected with switching time on the order of tens of nanoseconds. Heat flux modulation is based on the interplay between radiative heat transfer at the nanoscale and phase change materials. Such large contrasts are not obtainable in solids, or in far field. As such this opens up new horizons for temperature modulation and actuation at the nanoscale.

Single molecules and single nanoparticles as windows to the nanoscale

Science.gov (United States)

Caldarola, Martín; Orrit, Michel

2018-05-01

Since the first optical detection of single molecules, they have been used as nanometersized optical sensors to explore the physical properties of materials and light-matter interaction at the nanoscale. Understanding nanoscale properties of materials is fundamental for the development of new technology that requires precise control of atoms and molecules when the quantum nature of matter cannot be ignored. In the following lines, we illustrate this journey into nanoscience with some experiments from our group.

Ellipsometry at the nanoscale

CERN Document Server

Hingerl, Kurt

2013-01-01

This book presents and introduces ellipsometry in nanoscience and nanotechnology making a bridge between the classical and nanoscale optical behaviour of materials. It delineates the role of the non-destructive and non-invasive optical diagnostics of ellipsometry in improving science and technology of nanomaterials and related processes by illustrating its exploitation, ranging from fundamental studies of the physics and chemistry of nanostructures to the ultimate goal of turnkey manufacturing control. This book is written for a broad readership: materials scientists, researchers, engineers, as well as students and nanotechnology operators who want to deepen their knowledge about both basics and applications of ellipsometry to nanoscale phenomena. It starts as a general introduction for people curious to enter the fields of ellipsometry and polarimetry applied to nanomaterials and progresses to articles by experts on specific fields that span from plasmonics, optics, to semiconductors and flexible electronics...

Nanoscale surface modification for enhanced biosensing a journey toward better glucose monitoring

CERN Document Server

Zhang, Guigen

2015-01-01

This book gives a comprehensive overview of electrochemical-based biosensors and their crucial components. Practical examples are given throughout the text to illustrate how the performance of electrochemical-based biosensors can be improved by nanoscale surface modification and how an optimal design can be achieved. All essential aspects of biosensors are considered, including electrode functionalization, efficiency of the mass transport of reactive species, and long term durability and functionality of the sensor. This book also: ·       Explains how the performance of an electrochemical-based biosensor can be improved by nanoscale surface modification ·       Gives readers the tools to evaluate and improve the performance of a biosensor with a multidisciplinary approach that considers electrical, electrostatic, electrochemical, chemical, and biochemical events ·       Links the performance of a sensor to the various governing physical and chemical principles so readers can fully unders...

The synthesis and properties of nanoscale ionic materials

KAUST Repository

Rodriguez, Robert Salgado

2010-02-17

In this article we discuss the effect of constituents on structure, flow, and thermal properties of nanoscale ionic materials (NIMs). NIMs are a new class of nanohybrids consisting of a nanometer-sized core, a charged corona covalently attached to the core, and an oppositely charged canopy. The hybrid nature of NIMs allows for their properties to be engineered by selectively varying their components. The unique properties associated with these systems can help overcome some of the issues facing the implementation of nanohybrids to various commercial applications, including carbon dioxide capture,water desalinization and as lubricants. Copyright © 2010 John Wiley & Sons, Ltd.

Surface Effects on Nanoscale Gas Flows

Science.gov (United States)

Beskok, Ali; Barisik, Murat

2010-11-01

3D MD simulations of linear Couette flow of argon gas confined within nano-scale channels are performed in the slip, transition and free molecular flow regimes. The velocity and density profiles show deviations from the kinetic theory based predictions in the near wall region that typically extends three molecular diameters (s) from each surface. Utilizing the Irwin-Kirkwood theorem, stress tensor components for argon gas confined in nano-channels are investigated. Outside the 3s region, three normal stress components are identical, and equal to pressure predicted using the ideal gas law, while the shear stress is a constant. Within the 3s region, the normal stresses become anisotropic and the shear stress shows deviations from its bulk value due to the surface virial effects. Utilizing the kinetic theory and MD predicted shear stress values, the tangential momentum accommodation coefficient for argon gas interacting with FCC structured walls (100) plane facing the fluid is calculated to be 0.75; this value is independent of the Knudsen number. Results show emergence of the 3s region as an additional characteristic length scale in nano-confined gas flows.

Control of friction at the nanoscale

Science.gov (United States)

Barhen, Jacob; Braiman, Yehuda Y.; Protopopescu, Vladimir

2010-04-06

Methods and apparatus are described for control of friction at the nanoscale. A method of controlling frictional dynamics of a plurality of particles using non-Lipschitzian control includes determining an attribute of the plurality of particles; calculating an attribute deviation by subtracting the attribute of the plurality of particles from a target attribute; calculating a non-Lipschitzian feedback control term by raising the attribute deviation to a fractionary power .xi.=(2m+1)/(2n+1) where n=1, 2, 3 . . . and m=0, 1, 2, 3 . . . , with m strictly less than n and then multiplying by a control amplitude; and imposing the non-Lipschitzian feedback control term globally on each of the plurality of particles; imposing causes a subsequent magnitude of the attribute deviation to be reduced.

Uncovering Design Principles of Intermediate Filaments, a Self-Assembling Biomaterial: Lessons in Nanoscale Materials Design

National Research Council Canada - National Science Library

Lee, David H

2007-01-01

.... Such proteins may be harnessed for military purposes (eg. protective self-healing materials or nanoscale scaffolds) if one had a better understanding of how molecular structure determines material properties. In this final progress report, we summarize our studies on these systems.

Synthesis, dynamics and photophysics of nanoscale systems

Science.gov (United States)

Mirkovic, Tihana

The emerging field of nanotechnology, which spans diverse areas such as nanoelectronics, medicine, chemical and pharmaceutical industries, biotechnology and computation, focuses on the development of devices whose improved performance is based on the utilization of self-assembled nanoscale components exhibiting unique properties owing to their miniaturized dimensions. The first phase in the conception of such multifunctional devices based on integrated technologies requires the study of basic principles behind the functional mechanism of nanoscale components, which could originate from individual nanoobjects or result as a collective behaviour of miniaturized unit structures. The comprehensive studies presented in this thesis encompass the mechanical, dynamical and photophysical aspects of three nanoscale systems. A newly developed europium sulfide nanocrystalline material is introduced. Advances in synthetic methods allowed for shape control of surface-functionalized EuS nanocrystals and the fabrication of multifunctional EuS-CdSe hybrid particles, whose unique structural and optical properties hold promise as useful attributes of integrated materials in developing technologies. A comprehensive study based on a new class of multifunctional nanomaterials, derived from the basic unit of barcoded metal nanorods is presented. Their chemical composition affords them the ability to undergo autonomous motion in the presence of a suitable fuel. The nature of their chemically powered self-propulsion locomotion was investigated, and plausible mechanisms for various motility modes were presented. Furthermore functionalization of striped metallic nanorods has been realized through the incorporation of chemically controlled flexible hinges displaying bendable properties. The structural aspect of the light harvesting machinery of a photosynthetic cryptophyte alga, Rhodomonas CS24, and the mobility of the antenna protein, PE545, in vivo were investigated. Information obtained

Feedback System Control Optimized Electrospinning for Fabrication of an Excellent Superhydrophobic Surface.

Science.gov (United States)

Yang, Jian; Liu, Chuangui; Wang, Boqian; Ding, Xianting

2017-10-13

Superhydrophobic surface, as a promising micro/nano material, has tremendous applications in biological and artificial investigations. The electrohydrodynamics (EHD) technique is a versatile and effective method for fabricating micro- to nanoscale fibers and particles from a variety of materials. A combination of critical parameters, such as mass fraction, ratio of N, N-Dimethylformamide (DMF) to Tetrahydrofuran (THF), inner diameter of needle, feed rate, receiving distance, applied voltage as well as temperature, during electrospinning process, to determine the morphology of the electrospun membranes, which in turn determines the superhydrophobic property of the membrane. In this study, we applied a recently developed feedback system control (FSC) scheme for rapid identification of the optimal combination of these controllable parameters to fabricate superhydrophobic surface by one-step electrospinning method without any further modification. Within five rounds of experiments by testing totally forty-six data points, FSC scheme successfully identified an optimal parameter combination that generated electrospun membranes with a static water contact angle of 160 degrees or larger. Scanning electron microscope (SEM) imaging indicates that the FSC optimized surface attains unique morphology. The optimized setup introduced here therefore serves as a one-step, straightforward, and economic approach to fabricate superhydrophobic surface with electrospinning approach.

Modeling investigation of the stability and irradiation-induced evolution of nanoscale precipitates in advanced structural materials

International Nuclear Information System (INIS)

Wirth, Brian

2015-01-01

Materials used in extremely hostile environment such as nuclear reactors are subject to a high flux of neutron irradiation, and thus vast concentrations of vacancy and interstitial point defects are produced because of collisions of energetic neutrons with host lattice atoms. The fate of these defects depends on various reaction mechanisms which occur immediately following the displacement cascade evolution and during the longer-time kinetically dominated evolution such as annihilation, recombination, clustering or trapping at sinks of vacancies, interstitials and their clusters. The long-range diffusional transport and evolution of point defects and self-defect clusters drive a microstructural and microchemical evolution that are known to produce degradation of mechanical properties including the creep rate, yield strength, ductility, or fracture toughness, and correspondingly affect material serviceability and lifetimes in nuclear applications. Therefore, a detailed understanding of microstructural evolution in materials at different time and length scales is of significant importance. The primary objective of this work is to utilize a hierarchical computational modeling approach i) to evaluate the potential for nanoscale precipitates to enhance point defect recombination rates and thereby the self-healing ability of advanced structural materials, and ii) to evaluate the stability and irradiation-induced evolution of such nanoscale precipitates resulting from enhanced point defect transport to and annihilation at precipitate interfaces. This project will utilize, and as necessary develop, computational materials modeling techniques within a hierarchical computational modeling approach, principally including molecular dynamics, kinetic Monte Carlo and spatially-dependent cluster dynamics modeling, to identify and understand the most important physical processes relevant to promoting the ''selfhealing'' or radiation resistance in advanced

Modeling investigation of the stability and irradiation-induced evolution of nanoscale precipitates in advanced structural materials

Energy Technology Data Exchange (ETDEWEB)

Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States)

2015-04-08

Materials used in extremely hostile environment such as nuclear reactors are subject to a high flux of neutron irradiation, and thus vast concentrations of vacancy and interstitial point defects are produced because of collisions of energetic neutrons with host lattice atoms. The fate of these defects depends on various reaction mechanisms which occur immediately following the displacement cascade evolution and during the longer-time kinetically dominated evolution such as annihilation, recombination, clustering or trapping at sinks of vacancies, interstitials and their clusters. The long-range diffusional transport and evolution of point defects and self-defect clusters drive a microstructural and microchemical evolution that are known to produce degradation of mechanical properties including the creep rate, yield strength, ductility, or fracture toughness, and correspondingly affect material serviceability and lifetimes in nuclear applications. Therefore, a detailed understanding of microstructural evolution in materials at different time and length scales is of significant importance. The primary objective of this work is to utilize a hierarchical computational modeling approach i) to evaluate the potential for nanoscale precipitates to enhance point defect recombination rates and thereby the self-healing ability of advanced structural materials, and ii) to evaluate the stability and irradiation-induced evolution of such nanoscale precipitates resulting from enhanced point defect transport to and annihilation at precipitate interfaces. This project will utilize, and as necessary develop, computational materials modeling techniques within a hierarchical computational modeling approach, principally including molecular dynamics, kinetic Monte Carlo and spatially-dependent cluster dynamics modeling, to identify and understand the most important physical processes relevant to promoting the “selfhealing” or radiation resistance in advanced materials containing

76 FR 41178 - Pesticides; Policies Concerning Products Containing Nanoscale Materials; Opportunity for Public...

Science.gov (United States)

2011-07-13

... Pesticides; Policies Concerning Products Containing Nanoscale Materials; Opportunity for Public Comment; Extension of Comment Period AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed policy statement; extension of comment period. SUMMARY: EPA issued a proposed policy statement in the Federal Register of June...

Nanoscale heat transfer in carbon nanotube - sugar alcohol composites as heat storage materials

NARCIS (Netherlands)

Zhang, H.; Rindt, C.C.M.; Smeulders, D.M.J.; Gaastra - Nedea, S.V.

2016-01-01

Nanoscale carbon structures such as graphene and carbon nanotubes (CNTs) can greatly improve the effective thermal conductivity of thermally sluggish heat storage materials, such as sugar alcohols (SAs). The specific improvement depends on the heat transfer rate across the carbon structure. Besides,

Dynamics at the nanoscale

International Nuclear Information System (INIS)

Stoneham, A.M.; Gavartin, J.L.

2007-01-01

However fascinating structures may be at the nanoscale, time-dependent behaviour at the nanoscale has far greater importance. Some of the dynamics is random, with fluctuations controlling rate processes and making thermal ratchets possible. Some of the dynamics causes the transfer of energy, of signals, or of charge. Such transfers are especially efficiently controlled in biological systems. Other dynamical processes occur when we wish to control the nanoscale, e.g., to avoid local failures of gate dielectrics, or to manipulate structures by electronic excitation, to use spin manipulation in quantum information processing. Our prime purpose is to make clear the enormous range and variety of time-dependent nanoscale phenomena

Supercapacitors - nanostructured materials and nanoscale processes contributing to the next mobile generation

International Nuclear Information System (INIS)

Mahon, P.J.; Drummond, C.J.

2001-01-01

Supercapacitors, alternatively known as ultracapacitors, electrical double-layer capacitors or electrochemical capacitors, are energy storage devices that have considerably more specific capacitance than conventional capacitors. In recent years there have been major advancements in the design of low impedance (low resistance) Supercapacitors, which are ideally suited for high-power applications for mobile devices, particularly those using GSM (Global System for Mobile communication) and GPRS (General Packet Radio Service) wireless technologies. Cap-XX Pty Ltd is a global leader in supercapacitor technology. Cap-XX was established in 1997 and evolved from a collaboration that began in 1994 between Plessey Ducon Pty Ltd, a company that manufactured metallized film capacitors, and what is now CSIRO Energy Technology. In this article we outline the physical chemistry, and in particular, the colloid and surface, electro-, and polymer chemistry, elements that underpin supercapacitor performance. The emphasis is placed on high surface area, particulate-carbon-based supercapacitor technology. This is the cap-XX technology. It is a good example of nanostructured materials and nanoscale processes governing device performance. Some application areas for Supercapacitors are highlighted at the end of this article. Copyright (2001) CSIRO Australia

Real-Space Imaging of Carrier Dynamics of Materials Surfaces by Second-Generation Four-Dimensional Scanning Ultrafast Electron Microscopy

KAUST Repository

Sun, Jingya

2015-09-14

In the fields of photocatalysis and photovoltaics, ultrafast dynamical processes, including carrier trapping and recombination on material surfaces, are among the key factors that determine the overall energy conversion efficiency. A precise knowledge of these dynamical events on the nanometer (nm) and femtosecond (fs) scales was not accessible until recently. The only way to access such fundamental processes fully is to map the surface dynamics selectively in real space and time. In this study, we establish a second generation of four-dimensional scanning ultrafast electron microscopy (4D S-UEM) and demonstrate the ability to record time-resolved images (snapshots) of material surfaces with 650 fs and ∼5 nm temporal and spatial resolutions, respectively. In this method, the surface of a specimen is excited by a clocking optical pulse and imaged using a pulsed primary electron beam as a probe pulse, generating secondary electrons (SEs), which are emitted from the surface of the specimen in a manner that is sensitive to the local electron/hole density. This method provides direct and controllable information regarding surface dynamics. We clearly demonstrate how the surface morphology, grains, defects, and nanostructured features can significantly impact the overall dynamical processes on the surface of photoactive-materials. In addition, the ability to access two regimes of dynamical probing in a single experiment and the energy loss of SEs in semiconductor-nanoscale materials will also be discussed.

Quantified Differentiation of Surface Topography for Nano-materials As-Obtained from Atomic Force Microscopy Images

Science.gov (United States)

Gupta, Mousumi; Chatterjee, Somenath

2018-04-01

Surface texture is an important issue to realize the nature (crest and trough) of surfaces. Atomic force microscopy (AFM) image is a key analysis for surface topography. However, in nano-scale, the nature (i.e., deflection or crack) as well as quantification (i.e., height or depth) of deposited layers is essential information for material scientist. In this paper, a gradient-based K-means algorithm is used to differentiate the layered surfaces depending on their color contrast of as-obtained from AFM images. A transformation using wavelet decomposition is initiated to extract the information about deflection or crack on the material surfaces from the same images. Z-axis depth analysis from wavelet coefficients provides information about the crack present in the material. Using the above method corresponding surface information for the material is obtained. In addition, the Gaussian filter is applied to remove the unwanted lines, which occurred during AFM scanning. Few known samples are taken as input, and validity of the above approaches is shown.

Non-Planar Nano-Scale Fin Field Effect Transistors on Textile, Paper, Wood, Stone, and Vinyl via Soft Material-Enabled Double-Transfer Printing

KAUST Repository

Rojas, Jhonathan Prieto; Sevilla, Galo T.; Alfaraj, Nasir; Ghoneim, Mohamed T.; Kutbee, Arwa T.; Sridharan, Ashvitha; Hussain, Muhammad Mustafa

2015-01-01

The ability to incorporate rigid but high-performance nano-scale non-planar complementary metal-oxide semiconductor (CMOS) electronics with curvilinear, irregular, or asymmetric shapes and surfaces is an arduous but timely challenge in enabling the production of wearable electronics with an in-situ information-processing ability in the digital world. Therefore, we are demonstrating a soft-material enabled double-transfer-based process to integrate flexible, silicon-based, nano-scale, non-planar, fin-shaped field effect transistors (FinFETs) and planar metal-oxide-semiconductor field effect transistors (MOSFETs) on various asymmetric surfaces to study their compatibility and enhanced applicability in various emerging fields. FinFET devices feature sub-20 nm dimensions and state-of-the-art, high-κ/metal gate stack, showing no performance alteration after the transfer process. A further analysis of the transferred MOSFET devices, featuring 1 μm gate length exhibits ION ~70 μA/μm (VDS = 2 V, VGS = 2 V) and a low sub-threshold swing of around 90 mV/dec, proving that a soft interfacial material can act both as a strong adhesion/interposing layer between devices and final substrate as well as a means to reduce strain, which ultimately helps maintain the device’s performance with insignificant deterioration even at a high bending state.

Non-Planar Nano-Scale Fin Field Effect Transistors on Textile, Paper, Wood, Stone, and Vinyl via Soft Material-Enabled Double-Transfer Printing

KAUST Repository

Rojas, Jhonathan Prieto

2015-05-01

The ability to incorporate rigid but high-performance nano-scale non-planar complementary metal-oxide semiconductor (CMOS) electronics with curvilinear, irregular, or asymmetric shapes and surfaces is an arduous but timely challenge in enabling the production of wearable electronics with an in-situ information-processing ability in the digital world. Therefore, we are demonstrating a soft-material enabled double-transfer-based process to integrate flexible, silicon-based, nano-scale, non-planar, fin-shaped field effect transistors (FinFETs) and planar metal-oxide-semiconductor field effect transistors (MOSFETs) on various asymmetric surfaces to study their compatibility and enhanced applicability in various emerging fields. FinFET devices feature sub-20 nm dimensions and state-of-the-art, high-κ/metal gate stack, showing no performance alteration after the transfer process. A further analysis of the transferred MOSFET devices, featuring 1 μm gate length exhibits ION ~70 μA/μm (VDS = 2 V, VGS = 2 V) and a low sub-threshold swing of around 90 mV/dec, proving that a soft interfacial material can act both as a strong adhesion/interposing layer between devices and final substrate as well as a means to reduce strain, which ultimately helps maintain the device’s performance with insignificant deterioration even at a high bending state.

Micro- and nanoscale characterization of hydrophobic and hydrophilic leaf surfaces

International Nuclear Information System (INIS)

Bhushan, Bharat; Jung, Yong Chae

2006-01-01

Superhydrophobic surfaces as well as low adhesion and friction are desirable for various industrial applications. Certain plant leaves are known to be hydrophobic in nature due to their roughness and the presence of a thin wax film on the surface of the leaf. The purpose of this study is to fully characterize the leaf surfaces on the micro- and nanoscale while separating out the effects of the micro- and the nanobumps of hydrophobic leaves on the hydrophobicity. Hydrophilic leaves were also studied to better understand the role of wax and roughness. Furthermore, the adhesion and friction properties of hydrophobic and hydrophilic leaves were studied. Using an optical profiler and an atomic/friction force microscope (AFM/FFM), measurements were made to fully characterize the leaf surfaces. It is shown that the nanobumps play a more important role than the microbumps in the hydrophobic nature as well as friction of the leaf. This study will be useful in developing superhydrophobic surfaces

Creating nanoscale emulsions using condensation.

Science.gov (United States)

Guha, Ingrid F; Anand, Sushant; Varanasi, Kripa K

2017-11-08

Nanoscale emulsions are essential components in numerous products, ranging from processed foods to novel drug delivery systems. Existing emulsification methods rely either on the breakup of larger droplets or solvent exchange/inversion. Here we report a simple, scalable method of creating nanoscale water-in-oil emulsions by condensing water vapor onto a subcooled oil-surfactant solution. Our technique enables a bottom-up approach to forming small-scale emulsions. Nanoscale water droplets nucleate at the oil/air interface and spontaneously disperse within the oil, due to the spreading dynamics of oil on water. Oil-soluble surfactants stabilize the resulting emulsions. We find that the oil-surfactant concentration controls the spreading behavior of oil on water, as well as the peak size, polydispersity, and stability of the resulting emulsions. Using condensation, we form emulsions with peak radii around 100 nm and polydispersities around 10%. This emulsion formation technique may open different routes to creating emulsions, colloidal systems, and emulsion-based materials.

Synthesis, fabrication, and spectroscopy of nano-scale photonic noble metal materials

Science.gov (United States)

Egusa, Shunji

Nanometer is an interesting scale for physicists, chemists, and materials scientists, in a sense that it lies between the macroscopic and the atomic scales. In this regime, materials exhibit distinct physical and chemical properties that are clearly different from those of atoms or macroscopic bulk. This thesis is concerned about both physics and chemistry of noble metal nano-structures. Novel chemical syntheses and physical fabrications of various noble metal nano-structures, and the development of spectroscopic techniques for nano-structures are presented. Scanning microscopy/spectroscopy techniques inherently perturbs the true optical responses of the nano-structures. However, by using scanning tunneling microscope (STM) tip as the nanometer-confined excitation source of surface plasmons in the samples, and subsequently collecting the signals in the Fourier space, it is shown that the tip-perturbed part of the signals can be deconvoluted. As a result, the collected signal in this approach is the pure response of the sample. Coherent light is employed to study the optical response of nano-structures, in order to avoid complication from tip-perturbation as discussed above. White-light super-continuum excites the nano-structure, the monolayer of Au nanoparticles self-assembled on silicon nitride membrane substrates. The coherent excitation reveals asymmetric surface plasmon resonance in the nano-structures. One of the most important issues in nano-scale science is to gain control over the shape, size, and assembly of nanoparticles. A novel method is developed to chemically synthesize ligand-passivated atomic noble metal clusters in solution phase. The method, named thermal decomposition method, enables facile yet robust synthesis of fluorescent atomic clusters. Thus synthesized atomic clusters are very stable, and show behaviors of quantum dots. A novel and versatile approach for creation of nanoparticle arrays is developed. This method is different from the

Forces that Drive Nanoscale Self-assembly on Solid Surfaces

International Nuclear Information System (INIS)

Suo, Z.; Lu, W.

2000-01-01

Experimental evidence has accumulated in the recent decade that nanoscale patterns can self-assemble on solid surfaces. A two-component monolayer grown on a solid surface may separate into distinct phases. Sometimes the phases select sizes about 10 nm, and order into an array of stripes or disks. This paper reviews a model that accounts for these behaviors. Attention is focused on thermodynamic forces that drive the self-assembly. A double-welled, composition-dependent free energy drives phase separation. The phase boundary energy drives phase coarsening. The concentration-dependent surface stress drives phase refining. It is the competition between the coarsening and the refining that leads to size selection and spatial ordering. These thermodynamic forces are embodied in a nonlinear diffusion equation. Numerical simulations reveal rich dynamics of the pattern formation process. It is relatively fast for the phases to separate and select a uniform size, but exceedingly slow to order over a long distance, unless the symmetry is suitably broken

Light-matter interaction physics and engineering at the nanoscale

CERN Document Server

Weiner, John

2013-01-01

This book draws together the essential elements of classical electrodynamics, surface wave physics, plasmonic materials, and circuit theory of electrical engineering to provide insight into the essential physics of nanoscale light-matter interaction and to provide design methodology for practical nanoscale plasmonic devices. A chapter on classical and quantal radiation also highlights the similarities (and differences) between the classical fields of Maxwell's equations and the wave functions of Schrodinger's equation. The aim of this chapter is to provide a semiclassical picture of atomic absorption and emission of radiation, lending credence and physical plausibility to the "rules" of standard wave-mechanical calculations.

Revealing Nanoscale Passivation and Corrosion Mechanisms of Reactive Battery Materials in Gas Environments.

Science.gov (United States)

Li, Yuzhang; Li, Yanbin; Sun, Yongming; Butz, Benjamin; Yan, Kai; Koh, Ai Leen; Zhao, Jie; Pei, Allen; Cui, Yi

2017-08-09

Lithium (Li) metal is a high-capacity anode material (3860 mAh g -1 ) that can enable high-energy batteries for electric vehicles and grid-storage applications. However, Li metal is highly reactive and repeatedly consumed when exposed to liquid electrolyte (during battery operation) or the ambient environment (throughout battery manufacturing). Studying these corrosion reactions on the nanoscale is especially difficult due to the high chemical reactivity of both Li metal and its surface corrosion films. Here, we directly generate pure Li metal inside an environmental transmission electron microscope (TEM), revealing the nanoscale passivation and corrosion process of Li metal in oxygen (O 2 ), nitrogen (N 2 ), and water vapor (H 2 O). We find that while dry O 2 and N 2 (99.9999 vol %) form uniform passivation layers on Li, trace water vapor (∼1 mol %) disrupts this passivation and forms a porous film on Li metal that allows gas to penetrate and continuously react with Li. To exploit the self-passivating behavior of Li in dry conditions, we introduce a simple dry-N 2 pretreatment of Li metal to form a protective layer of Li nitride prior to battery assembly. The fast ionic conductivity and stable interface of Li nitride results in improved battery performance with dendrite-free cycling and low voltage hysteresis. Our work reveals the detailed process of Li metal passivation/corrosion and demonstrates how this mechanistic insight can guide engineering solutions for Li metal batteries.

Nuclear Magnetic Resonance Study of Nanoscale Ionic Materials

KAUST Repository

Oommen, Joanna Mary

2010-08-13

Nanoscale ionic materials (NIMs) are a new class of nanomaterials that exhibit interesting properties including negligible vapor pressures and tunable physical states, among others. In this study, we analyzed the temperature-wise performance of NIMs using nuclear magnetic resonance (NMR) spectroscopy. NIMs are relatively stable over a temperature range from 300 to 383 K, rendering them usable in high temperature applications. We confirmed the presence of covalent bonds between the SiO2 core and the sulfonate group and determined relative concentrations of aromatic and aliphatic hydrocarbons. These findings serve as first hand proof-of-concept for the usefulness of NMR analyses in further studies on the diffusive properties of NIMs. © 2010 The Electrochemical Society.

Two-dimensional Cu2Si sheet: a promising electrode material for nanoscale electronics

Science.gov (United States)

Meng Yam, Kah; Guo, Na; Zhang, Chun

2018-06-01

Building electronic devices on top of two-dimensional (2D) materials has recently become one of most interesting topics in nanoelectronics. Finding high-performance 2D electrode materials is one central issue in 2D nanoelectronics. In the current study, based on first-principles calculations, we compare the electronic and transport properties of two nanoscale devices. One device consists of two single-atom-thick planar Cu2Si electrodes, and a nickel phthalocyanine (NiPc) molecule in the middle. The other device is made of often-used graphene electrodes and a NiPc molecule. Planer Cu2Si is a new type of 2D material that was recently predicted to exist and be stable under room temperature [11]. We found that at low bias voltages, the electric current through the Cu2Si–NiPc–Cu2Si junction is about three orders higher than that through graphene–NiPc–graphene. Detailed analysis shows that the surprisingly high conductivity of Cu2Si–NiPc–Cu2Si originates from the mixing of the Cu2Si state near Fermi energy and the highest occupied molecular orbital of NiPc. These results suggest that 2D Cu2Si may be an excellent candidate for electrode materials for future nanoscale devices.

Nanoscale Electrical Potential and Roughness of a Calcium Phosphate Surface Promotes the Osteogenic Phenotype of Stromal Cells

Directory of Open Access Journals (Sweden)

Igor A. Khlusov

2018-06-01

Full Text Available Mesenchymal stem cells (MSCs and osteoblasts respond to the surface electrical charge and topography of biomaterials. This work focuses on the connection between the roughness of calcium phosphate (CP surfaces and their electrical potential (EP at the micro- and nanoscales and the possible role of these parameters in jointly affecting human MSC osteogenic differentiation and maturation in vitro. A microarc CP coating was deposited on titanium substrates and characterized at the micro- and nanoscale. Human adult adipose-derived MSCs (hAMSCs or prenatal stromal cells from the human lung (HLPSCs were cultured on the CP surface to estimate MSC behavior. The roughness, nonuniform charge polarity, and EP of CP microarc coatings on a titanium substrate were shown to affect the osteogenic differentiation and maturation of hAMSCs and HLPSCs in vitro. The surface EP induced by the negative charge increased with increasing surface roughness at the microscale. The surface relief at the nanoscale had an impact on the sign of the EP. Negative electrical charges were mainly located within the micro- and nanosockets of the coating surface, whereas positive charges were detected predominantly at the nanorelief peaks. HLPSCs located in the sockets of the CP surface expressed the osteoblastic markers osteocalcin and alkaline phosphatase. The CP multilevel topography induced charge polarity and an EP and overall promoted the osteoblast phenotype of HLPSCs. The negative sign of the EP and its magnitude at the micro- and nanosockets might be sensitive factors that can trigger osteoblastic differentiation and maturation of human stromal cells.

Towards Realization of Intelligent Medical Treatment at Nanoscale by Artificial Microscopic Swarm Control Systems

Directory of Open Access Journals (Sweden)

Alireza Rowhanimanesh

2017-07-01

Full Text Available Background: In this paper, the novel concept of artificial microscopic swarm control systems is proposed as a promising approach towards realization of intelligent medical treatment at nanoscale. In this new paradigm, treatment is done autonomously at nanoscale within the patient’s body by the proposed swarm control systems.Methods: From control engineering perspective, medical treatment can be considered as a control problem, in which the ultimate goal is to find the best feasible way to change the state of diseased tissue from unhealthy to healthy in presence of uncertainty. Although a living tissue is a huge swarm of microscopic cells, nearly all of the common treatment methods are based on macroscopic centralized control paradigm. Inspired by natural microscopic swarm control systems such as nervous, endocrine and immune systems that work based on swarm control paradigm, medical treatment needs a paradigm shift from macroscopic centralized control to microscopic swarm control. An artificial microscopic swarm control system consists of a huge number of very simple autonomous microscopic agents that exploit swarm intelligence to realize sense, control (computing and actuation at nanoscale in local, distributed and decentralized manner. This control system can be designed based on mathematical analysis and computer simulation.Results: The proposed approach is used for treatment of atherosclerosis and cancer based on mathematical analysis and in-silico study.Conclusion: The notion of artificial microscopic swarm control systems opens new doors towards realization of autonomous and intelligent medical treatment at nanoscale within the patient’s body.

Directed transport by surface chemical potential gradients for enhancing analyte collection in nanoscale sensors.

Science.gov (United States)

Sitt, Amit; Hess, Henry

2015-05-13

Nanoscale detectors hold great promise for single molecule detection and the analysis of small volumes of dilute samples. However, the probability of an analyte reaching the nanosensor in a dilute solution is extremely low due to the sensor's small size. Here, we examine the use of a chemical potential gradient along a surface to accelerate analyte capture by nanoscale sensors. Utilizing a simple model for transport induced by surface binding energy gradients, we study the effect of the gradient on the efficiency of collecting nanoparticles and single and double stranded DNA. The results indicate that chemical potential gradients along a surface can lead to an acceleration of analyte capture by several orders of magnitude compared to direct collection from the solution. The improvement in collection is limited to a relatively narrow window of gradient slopes, and its extent strongly depends on the size of the gradient patch. Our model allows the optimization of gradient layouts and sheds light on the fundamental characteristics of chemical potential gradient induced transport.

Investigations on a nano-scale periodical waveguide structure taking surface plasmon polaritons into consideration

International Nuclear Information System (INIS)

Liu Weihao; Zhong Renbin; Zhou Jun; Zhang Yaxin; Hu Min; Liu Shenggang

2012-01-01

Detailed theoretical analysis and computer simulations on the electromagnetic characteristics of a nano-scale periodical waveguide structure, taking surface plasmon polaritons (SPPs) into consideration, are carried out in this paper. The results show that SPPs will significantly influence the electromagnetic characteristics of the structure. When the operation frequency is in a certain band—the ‘radial confinement band’, neither radial surface plasmon waves nor guided waves, which both will lead to radial energy loss, can be excited in the structure. And the electromagnetic waves are completely confined within the longitudinal waveguide and propagate along it with little attenuation. The radial energy loss is then significantly reduced. These results are of great significance not only for increasing the efficiency of the radiation sources based on the nano-scale periodical waveguide structure but also for the development of high-efficiency waveguides and wide-band filters in the infrared and visible light regimes. (paper)

Deconvoluting the effects of surface chemistry and nanoscale topography: Pseudomonas aeruginosa biofilm nucleation on Si-based substrates.

Science.gov (United States)

Zhang, Jing; Huang, Jinglin; Say, Carmen; Dorit, Robert L; Queeney, K T

2018-06-01

The nucleation of biofilms is known to be affected by both the chemistry and topography of the underlying substrate, particularly when topography includes nanoscale (topography vs. chemistry is complicated by concomitant variation in both as a result of typical surface modification techniques. Analyzing the behavior of biofilm-forming bacteria exposed to surfaces with systematic, independent variation of both topography and surface chemistry should allow differentiation of the two effects. Silicon surfaces with reproducible nanotopography were created by anisotropic etching in deoxygenated water. Surface chemistry was varied independently to create hydrophilic (OH-terminated) and hydrophobic (alkyl-terminated) surfaces. The attachment and proliferation of Psuedomonas aeruginosa to these surfaces was characterized over a period of 12 h using fluorescence and confocal microscopy. The number of attached bacteria as well as the structural characteristics of the nucleating biofilm were influenced by both surface nanotopography and surface chemistry. In general terms, the presence of both nanoscale features and hydrophobic surface chemistry enhance bacterial attachment and colonization. However, the structural details of the resulting biofilms suggest that surface chemistry and topography interact differently on each of the four surface types we studied. Copyright © 2018 Elsevier Inc. All rights reserved.

Nanoscale Ionic Liquids

Science.gov (United States)

2006-11-01

Technical Report 11 December 2005 - 30 November 2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Nanoscale Ionic Liquids 5b. GRANT NUMBER FA9550-06-1-0012...Title: Nanoscale Ionic Liquids Principal Investigator: Emmanuel P. Giannelis Address: Materials Science and Engineering, Bard Hall, Cornell University...based fluids exhibit high ionic conductivity. The NFs are typically synthesized by grafting a charged, oligomeric corona onto the nanoparticle cores

Nanoscale form dictates mesoscale function in plasmonic DNA–nanoparticle superlattices

Energy Technology Data Exchange (ETDEWEB)

Ross, Michael B.; Ku, Jessie C.; Vaccarezza, Victoria M.; Schatz, George C.; Mirkin , Chad A. (NWU)

2016-06-15

The nanoscale manipulation of matter allows properties to be created in a material that would be difficult or even impossible to achieve in the bulk state. Progress towards such functional nanoscale architectures requires the development of methods to precisely locate nanoscale objects in three dimensions and for the formation of rigorous structure–function relationships across multiple size regimes (beginning from the nanoscale). Here, we use DNA as a programmable ligand to show that two- and three-dimensional mesoscale superlattice crystals with precisely engineered optical properties can be assembled from the bottom up. The superlattices can transition from exhibiting the properties of the constituent plasmonic nanoparticles to adopting the photonic properties defined by the mesoscale crystal (here a rhombic dodecahedron) by controlling the spacing between the gold nanoparticle building blocks. Furthermore, we develop a generally applicable theoretical framework that illustrates how crystal habit can be a design consideration for controlling far-field extinction and light confinement in plasmonic metamaterial superlattices.

Recent Approaches to Controlling the Nanoscale Morphology of Polymer-Based Bulk-Heterojunction Solar Cells

Directory of Open Access Journals (Sweden)

Abdulra'uf Lukman Bola

2013-11-01

Full Text Available The need for clean, inexpensive and renewable energy has increasingly turned research attention towards polymer photovoltaic cells. However, the performance efficiency of these devices is still low in comparison with silicon-based devices. The recent introduction of new materials and processing techniques has resulted in a remarkable increase in power-conversion efficiency, with a value above 10%. Controlling the interpenetrating network morphology is a key factor in obtaining devices with improved performance. This review focuses on the influence of controlled nanoscale morphology on the overall performance of bulk-heterojunction (BHJ photovoltaic cells. Strategies such as the use of solvents, solvent annealing, polymer nanowires (NWs, and donor–acceptor (D–A blend ratios employed to control the active-layer morphologies are all discussed.

The role of energetic ions from plasma in the creation of nanostructured materials and stable polymer surface treatments

International Nuclear Information System (INIS)

Bilek, M.M.M.; Newton-McGee, K.; McKenzie, D.R.; McCulloch, D.G.

2006-01-01

Plasma processes for the synthesis of new materials as thin films have enabled the production of a wide variety of new materials. These include meta-stable phases, which are not readily found in nature, and more recently, materials with structure on the nanoscale. Study of plasma synthesis processes at the fundamental level has revealed that ion energy, depositing flux and growth surface temperature are the critical parameters affecting the microstructure and the properties of the thin film materials formed. In this paper, we focus on the role of ion flux and impact energy in the creation of thin films with nanoscale structure in the form of multilayers. We describe three synthesis strategies, based on the extraction of ions from plasma sources and involving modulation of ion flux and ion energy. The microstructure, intrinsic stress and physical properties of the multilayered samples synthesized are studied and related back to the conditions at the growth surface during deposition. When energetic ions of a non-condensing species are used, it is possible to place active groups on the surfaces of materials such as polymers. These active groups can then be used as bonding sites in subsequent chemical attachment of proteins or other macromolecules. If the energy of the non-condensing ions is increased to a few keV then modified layers buried under the surface can be produced. Here we describe a method by which the aging effect, which is often observed in plasma surface modifications on polymers, can be reduced and even eliminated using high energy ion bombardment

Analytical TEM investigations of nanoscale magnetic materials

International Nuclear Information System (INIS)

Meingast, A.

2015-01-01

Analytical transmission electron microscopy has been applied within this thesis to investigate several novel approaches to design and fabricate nanoscale magnetic materials. As the size of the features of interest rank in the sub-nanometer range, it is necessary to employ techniques with a resolution – both spatial and analytical – well below this magnitude. Only at this performance level it is possible to examine material properties, necessary for the further tailoring of materials. Within this work two key aspects have been covered: First, analytical TEM (transmission electron microscopy) investigations were carried out to get insight into novel magnetic materials with high detail. Second, new analytical and imaging possibilities enabled with the commissioning of the new ASTEM (Austrian scanning transmission electron microscope) were explored. The aberration corrected TITAN® microscope (© FEI Company) allows resolving features in scanning transmission mode (STEM) with 70 pm distance. Thereby, direct imaging of light elements in STEM mode by using the annular bright field method becomes possible. Facilitated through high beam currents within the electron probe, an increased acquisition speed of analytical signals is possible. For energy dispersive X-ray spectroscopy (EDXS) a new four detector disc geometry around the specimen was implemented, which increases the accessible collection angle. With the integration of the latest generation of image filter and electron spectrometer (GIF QuantumERS), electron energy loss spectroscopy (EELS) is boosted through the high acquisition speed and the dual spectroscopy mode. The high acquisition speed allows to record up to 1000 spectra per second and the possibility to record atomically resolved EELS maps is at hand. Hereby it is important to avoid beam damage and alteration of the material during imaging and analysis. With the simultaneous acquisition of the low and the high loss spectral region, an extended range for

Band-gap measurements of bulk and nanoscale hematite by soft x-ray spectroscopy

DEFF Research Database (Denmark)

Gilbert, B.; Frandsen, Cathrine; Maxey, E.R.

2009-01-01

Chemical and photochemical processes at semiconductor surfaces are highly influenced by the size of the band gap, and ability to control the band gap by particle size in nanomaterials is part of their promise. The combination of soft x-ray absorption and emission spectroscopies provides band......-gap determination in bulk and nanoscale itinerant electron semiconductors such as CdS and ZnO, but this approach has not been established for materials such as iron oxides that possess band-edge electronic structure dominated by electron correlations. We performed soft x-ray spectroscopy at the oxygen K...

Surface Plasmon-Mediated Nanoscale Localization of Laser-Driven sub-Terahertz Spin Dynamics in Magnetic Dielectrics

Science.gov (United States)

Chekhov, Alexander L.; Stognij, Alexander I.; Satoh, Takuya; Murzina, Tatiana V.; Razdolski, Ilya; Stupakiewicz, Andrzej

2018-05-01

Ultrafast all-optical control of spins with femtosecond laser pulses is one of the hot topics at the crossroads of photonics and magnetism with a direct impact on future magnetic recording. Unveiling light-assisted recording mechanisms for an increase of the bit density beyond the diffraction limit without excessive heating of the recording medium is an open challenge. Here we show that surface plasmon-polaritons in hybrid metal-dielectric structures can provide spatial confinement of the inverse Faraday effect, mediating the excitation of localized coherent spin precession with 0.41 THz frequency. We demonstrate a two orders of magnitude enhancement of the excitation efficiency at the surface plasmon resonance within the 100 nm layer in dielectric garnet. Our findings broaden the horizons of ultrafast spin-plasmonics and open pathways towards non-thermal opto-magnetic recording at the nano-scale.

Nanoscale thermal transport

Science.gov (United States)

Cahill, David G.; Ford, Wayne K.; Goodson, Kenneth E.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Merlin, Roberto; Phillpot, Simon R.

2003-01-01

Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding of thermal transport in nanoscale devices, individual nanostructures, and nanostructured materials. This review emphasizes developments in experiment, theory, and computation that have occurred in the past ten years and summarizes the present status of the field. Interfaces between materials become increasingly important on small length scales. The thermal conductance of many solid-solid interfaces have been studied experimentally but the range of observed interface properties is much smaller than predicted by simple theory. Classical molecular dynamics simulations are emerging as a powerful tool for calculations of thermal conductance and phonon scattering, and may provide for a lively interplay of experiment and theory in the near term. Fundamental issues remain concerning the correct definitions of temperature in nonequilibrium nanoscale systems. Modern Si microelectronics are now firmly in the nanoscale regime—experiments have demonstrated that the close proximity of interfaces and the extremely small volume of heat dissipation strongly modifies thermal transport, thereby aggravating problems of thermal management. Microelectronic devices are too large to yield to atomic-level simulation in the foreseeable future and, therefore, calculations of thermal transport must rely on solutions of the Boltzmann transport equation; microscopic phonon scattering rates needed for predictive models are, even for Si, poorly known. Low-dimensional nanostructures, such as carbon nanotubes, are predicted to have novel transport properties; the first quantitative experiments of the thermal conductivity of nanotubes have recently been achieved using microfabricated measurement systems. Nanoscale porosity decreases the permittivity of amorphous dielectrics but porosity also strongly decreases the thermal conductivity. The

Enhancement of Water Evaporation on Solid Surfaces with Nanoscale Hydrophobic-Hydrophilic Patterns.

Science.gov (United States)

Wan, Rongzheng; Wang, Chunlei; Lei, Xiaoling; Zhou, Guoquan; Fang, Haiping

2015-11-06

Using molecular dynamics simulations, we show that the evaporation of nanoscale water on hydrophobic-hydrophilic patterned surfaces is unexpectedly faster than that on any surfaces with uniform wettability. The key to this phenomenon is that, on the patterned surface, the evaporation rate from the hydrophilic region only slightly decreases due to the correspondingly increased water thickness; meanwhile, a considerable number of water molecules evaporate from the hydrophobic region despite the lack of water film. Most of the evaporated water from the hydrophobic region originates from the hydrophilic region by diffusing across the contact lines. Further analysis shows that the evaporation rate from the hydrophobic region is approximately proportional to the total length of the contact lines.

Micro- and nanoscale phenomena in tribology

CERN Document Server

Chung, Yip-Wah

2011-01-01

Drawn from presentations at a recent National Science Foundation Summer Institute on Nanomechanics, Nanomaterials, and Micro/Nanomanufacturing, Micro- and Nanoscale Phenomena in Tribology explores the convergence of the multiple science and engineering disciplines involved in tribology and the connection from the macro to nano world. Written by specialists from computation, materials science, mechanical engineering, surface physics, and chemistry, each chapter provides up-to-date coverage of both basic and advanced topics and includes extensive references for further study.After discussing the

Monolithic integration of nanoscale tensile specimens and MEMS structures

International Nuclear Information System (INIS)

Yilmaz, Mehmet; Kysar, Jeffrey W

2013-01-01

Nanoscale materials often have stochastic material properties due to a random distribution of material defects and an insufficient number of defects to ensure a consistent average mechanical response. Current methods to measure the mechanical properties employ MEMS-based actuators. The nanoscale specimens are typically mounted manually onto the load platform, so the boundary conditions have random variations, complicating the experimental measurement of the intrinsic stochasticity of the material properties. Here we show methods for monolithic integration of a nanoscale specimen co-fabricated with the loading platform. The nanoscale specimen is gold with dimensions of ∼40 nm thickness, 350 ± 50 nm width, and 7 μm length and the loading platform is an interdigitated electrode electrostatic actuator. The experiment is performed in a scanning electron microscope and digital image correlation is employed to measure displacements to determine stress and strain. The ultimate tensile strength of the nanocrystalline nanoscale specimen approaches 1 GPa, consistent with measurements made by other nanometer scale sample characterization methods on other material samples at the nanometer scale, as well as gold samples at the nanometer scale. The batch-compatible microfabrication method can be used to create nominally identical nanoscale specimens and boundary conditions for a broad range of materials. (paper)

Programmed assembly of nanoscale structures using peptoids.

Energy Technology Data Exchange (ETDEWEB)

Ren, Jianhua (University of the Pacific, Stockton, CA); Russell, Scott (California State University, Stanislaus, Turlock, CA); Morishetti, Kiran (University of the Pacific, Stockton, CA); Robinson, David B.; Zuckermann, Ronald N. (Lawrence Berkeley National Laboratory, Berkeley, CA); Buffleben, George M.; Hjelm, Rex P. (Los Alamos National Laboratory, Los Alamos, NM); Kent, Michael Stuart (Sandia National Laboratories, Albuquerque, NM)

2011-02-01

Sequence-specific polymers are the basis of the most promising approaches to bottom-up programmed assembly of nanoscale materials. Examples include artificial peptides and nucleic acids. Another class is oligo(N-functional glycine)s, also known as peptoids, which permit greater sidegroup diversity and conformational control, and can be easier to synthesize and purify. We have developed a set of peptoids that can be used to make inorganic nanoparticles more compatible with biological sequence-specific polymers so that they can be incorporated into nucleic acid or other biologically based nanostructures. Peptoids offer degrees of modularity, versatility, and predictability that equal or exceed other sequence-specific polymers, allowing for rational design of oligomers for a specific purpose. This degree of control will be essential to the development of arbitrarily designed nanoscale structures.

Nanoscale transformation of sp2 to sp3 of graphite by slow highly charged ion irradiation

International Nuclear Information System (INIS)

Meguro, T.; Hida, A.; Koguchi, Y.; Miyamoto, S.; Yamamoto, Y.; Takai, H.; Maeda, K.; Aoyagi, Y.

2003-01-01

Nanoscale transformation of electronic states by highly charged ion (HCI) impact on graphite surfaces is described. The high potential energy of slow HCI, which induces multiple emission of electrons from the surface, provides a strong modification of the electronic states of the local area upon graphite surfaces. The HCI impact and the subsequent surface treatment either by electron injection from a scanning tunneling microscopy tip or by He-Cd laser irradiation induce a localized transition from sp 2 to sp 3 hybridization in graphite, resulting in the formation of nanoscale diamond-like structures (nanodiamond) at the impact region. From Raman spectroscopic measurements on sp 2 related peaks, it is found that the HCI irradiation creates vacancy complexes in contrast to ions having a lower charge state, which generate single vacancies. It is of interest that a single impact of HCI creates one nanodiamond structure, suggesting potential applications of HCI in nanoscale material processing

Surface effects on the electroelastic responses of a thin piezoelectric plate with nanoscale thickness

International Nuclear Information System (INIS)

Yan Zhi; Jiang Liying

2012-01-01

This work aims to investigate the electroelastic responses of a thin piezoelectric plate under mechanical and electrical loads with the consideration of surface effects. Surface effects, including surface elasticity, residual surface stress and surface piezoelectricity, are incorporated into the conventional Kirchhoff plate theory for a piezoelectric plate via the surface piezoelectricity model and the generalized Young-Laplace equations. Different from the results predicted by the conventional plate theory ignoring the surface effects, the proposed model predicts size-dependent behaviours of the piezoelectric thin plate with nanoscale thickness. It is found that surface effects have significant influence on the electroelastic responses of the piezoelectric nanoplate. This work is expected to provide more accurate predictions on characterizing nanofilm or nanoribbon based piezoelectric devices in nanoelectromechanical systems. (paper)

Localized temperature and chemical reaction control in nanoscale space by nanowire array.

Science.gov (United States)

Jin, C Yan; Li, Zhiyong; Williams, R Stanley; Lee, K-Cheol; Park, Inkyu

2011-11-09

We introduce a novel method for chemical reaction control with nanoscale spatial resolution based on localized heating by using a well-aligned nanowire array. Numerical and experimental analysis shows that each individual nanowire could be selectively and rapidly Joule heated for local and ultrafast temperature modulation in nanoscale space (e.g., maximum temperature gradient 2.2 K/nm at the nanowire edge; heating/cooling time chemical reactions such as polymer decomposition/cross-linking and direct and localized hydrothermal synthesis of metal oxide nanowires were demonstrated.

Early Career. Harnessing nanotechnology for fusion plasma-material interface research in an in-situ particle-surface interaction facility

Energy Technology Data Exchange (ETDEWEB)

Allain, Jean Paul [Univ. of Illinois, Champaign, IL (United States)

2014-08-08

This project consisted of fundamental and applied research of advanced in-situ particle-beam interactions with surfaces/interfaces to discover novel materials able to tolerate intense conditions at the plasma-material interface (PMI) in future fusion burning plasma devices. The project established a novel facility that is capable of not only characterizing new fusion nanomaterials but, more importantly probing and manipulating materials at the nanoscale while performing subsequent single-effect in-situ testing of their performance under simulated environments in fusion PMI.

Enhanced electrochemical properties of LiNiO{sub 2}-based cathode materials by nanoscale manganese carbonate treatment

Energy Technology Data Exchange (ETDEWEB)

Zhao, Junkai; Wang, Zhixing, E-mail: zxwang.csu@hotmail.com; Guo, Huajun; Li, Xinhai

2017-05-01

Highlights: • Li residuals are consumed during the process of modification. • MnO{sub 2} coating layer can protect bulk material from the erosion of electrolyte. • The electrochemical performance is enhanced by the nanosacle MnCO{sub 3} treatment. • The enhancement of coating can be strengthened by the removal of lithium impurities. - Abstract: LiNiO{sub 2}-based layered oxides are of great importance as cathode materials for rechargeable batteries. In this paper, illustrating LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} as an example, the effect of nanoscale MnCO{sub 3} treatment on LiNiO{sub 2}-based materials is investigated for the first time. The structures of materials and the properties about the object surface are characterized by XRD, SEM, TEM, EDAX and XPS. The results demonstrate that a part of MnCO{sub 3} is able to react with lithium impurities to form nonstoichiometric Li{sub x}Mn{sub y}O{sub 4} and the rest of MnCO{sub 3} is converted to MnO{sub 2} coating on the surface of the material in situ. After 100 repeated cycles at 1C, the modified material exhibits a capacity retention rate of 91.2%, while the bare material only remains 84.8%. And the modified material exhibits more significantly improved cycling stability when cycling at 60 °C, maintaining 85.7% of its initial capacity at 1C after 100th cycles. The consumption of Li impurities can decelerate the decomposition of electrolyte during cycling, thus result in less resistive byproducts. Moreover, the obtained MnO{sub 2} coating layer acts as an isolating layer to suppress the drastic reaction between active material and electrolyte. This synergistic effect is responsible for the excellent properties of MnCO{sub 3}-modified material.

Self-assembly of fatty acids on hydroxylated Al surface and effects of their stability on wettability and nanoscale organization.

Science.gov (United States)

Liascukiene, Irma; Steffenhagen, Marie; Asadauskas, Svajus J; Lambert, Jean-François; Landoulsi, Jessem

2014-05-27

The self-assembly of fatty acids (FA) on the surfaces of inorganic materials is a relevant way to control their wetting properties. While the mechanism of adsorption on model flat substrate is well described in the literature, interfacial processes remain poorly documented on nanostructured surfaces. In this study, we report the self-assembly of a variety of FA on a hydroxylated Al surface which exhibits a random nanoscale organization. Our results revealed a peculiar fingerprint due to the FA self-assembly which consists in the formation of aligned nanopatterns in a state of hierarchical nanostructuration, regardless of the molecular structure of the FA (chain length, level of unsaturation). After a significant removal of adsorbed FA using UV/O3 treatment, a complete wetting was reached, and a noticeable disturbance of the surface morphology was observed, evidencing the pivotal role of FA molecules to maintain these nanostructures. The origin of wetting properties was investigated prior to and after conditioning of FA-modified samples taking into account key parameters, namely the surface roughness and its composition. For this purpose, the Wenzel roughness, defined as the third moment of power spectral density, was used, as it is sensitive to high spatial frequency and thus to the obtained hierarchical level of nanostructuration. Our results revealed that no correlation can be made between water contact angles (θ(w)) and the Wenzel roughness. By contrast, θ(w) strongly increased with the amount of -CHx- groups exhibited by adsorbed FA. These findings suggest that the main origin of hydrophobization is the presence of self-assembled molecules and that the surface roughness has only a small contribution to the wettability.

Patterned self-assembled monolayers for nanoscale lithography and the control of catalytically produced electroosmosis

Science.gov (United States)

Subramanian, Shyamala

This thesis explores two applications of self-assembled monolayers (SAMs) (a) for developing novel molecular assembly based nanolithography techniques and (b) for tailoring zeta-potential of surfaces towards achieving directional control of catalytically induced fluid flow. The first half of the thesis develops the process of molecular ruler lithography using sacrificial host structures. This is a novel hybrid nanolithography technique which combines chemical self-assembly with conventional fabrication methods for improving the resolution of existing lithography tools to sub-50 nm. Previous work related to molecular ruler lithography have shown the use of thiol-SAMs, placed one on top of the other like a molecular resist, for scaling down feature sizes. In this thesis various engineering solutions for improving the reproducibility, yield, nanoscale roughness and overall manufacturability of the process are introduced. This is achieved by introducing a sacrificial inert layer underneath the gold parent structure. This bilayer sacrificial host allows for preferential, easy and quick removal of the parent structures, isolates the parent metal from the underlying substrate and improves reproducibility of the lift-off process. Also it opens avenues for fabrication of high aspect ratio features. Also molecular layer vapor deposition method is developed for building the multilayer molecular resist via vapor phase to reduce contaminations and yield issues associated with solution phase deposition. The smallest isolated metal features produced using this process were 40 nm in width. The second half of the thesis describes application of thiol-SAMs to tailor surface properties of gold, specifically the surface charge or zeta potential. Previous work has demonstrated that the direction of movement of fluid in the vicinity of a catalytically active bimetallic junction placed in a solution of dilute hydrogen peroxide depends on the charge of the gold surface. SAMs with

Nanoscale thermal transport. II. 2003-2012

Science.gov (United States)

Cahill, David G.; Braun, Paul V.; Chen, Gang; Clarke, David R.; Fan, Shanhui; Goodson, Kenneth E.; Keblinski, Pawel; King, William P.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Phillpot, Simon R.; Pop, Eric; Shi, Li

2014-03-01

A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ˜ 1 nm , the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and thermal

Universal deformation pathways and flexural hardening of nanoscale 2D-material standing folds

Science.gov (United States)

Chacham, Helio; Barboza, Ana Paula M.; de Oliveira, Alan B.; de Oliveira, Camilla K.; Batista, Ronaldo J. C.; Neves, Bernardo R. A.

2018-03-01

In the present work, we use atomic force microscopy nanomanipulation of 2D-material standing folds to investigate their mechanical deformation. Using graphene, h-BN and talc nanoscale wrinkles as testbeds, universal force-strain pathways are clearly uncovered and well-accounted for by an analytical model. Such universality further enables the investigation of each fold bending stiffness κ as a function of its characteristic height h 0. We observe a more than tenfold increase of κ as h 0 increases in the 10-100 nm range, with power-law behaviors of κ versus h 0 with exponents larger than unity for the three materials. This implies anomalous scaling of the mechanical responses of nano-objects made from these materials.

Nanoscale-Agglomerate-Mediated Heterogeneous Nucleation.

Science.gov (United States)

Cha, Hyeongyun; Wu, Alex; Kim, Moon-Kyung; Saigusa, Kosuke; Liu, Aihua; Miljkovic, Nenad

2017-12-13

Water vapor condensation on hydrophobic surfaces has received much attention due to its ability to rapidly shed water droplets and enhance heat transfer, anti-icing, water harvesting, energy harvesting, and self-cleaning performance. However, the mechanism of heterogeneous nucleation on hydrophobic surfaces remains poorly understood and is attributed to defects in the hydrophobic coating exposing the high surface energy substrate. Here, we observe the formation of high surface energy nanoscale agglomerates on hydrophobic coatings after condensation/evaporation cycles in ambient conditions. To investigate the deposition dynamics, we studied the nanoscale agglomerates as a function of condensation/evaporation cycles via optical and field emission scanning electron microscopy (FESEM), microgoniometric contact angle measurements, nucleation statistics, and energy dispersive X-ray spectroscopy (EDS). The FESEM and EDS results indicated that the nanoscale agglomerates stem from absorption of sulfuric acid based aerosol particles inside the droplet and adsorption of volatile organic compounds such as methanethiol (CH 3 SH), dimethyl disulfide (CH 3 SSCH), and dimethyl trisulfide (CH 3 SSSCH 3 ) on the liquid-vapor interface during water vapor condensation, which act as preferential sites for heterogeneous nucleation after evaporation. The insights gained from this study elucidate fundamental aspects governing the behavior of both short- and long-term heterogeneous nucleation on hydrophobic surfaces, suggest previously unexplored microfabrication and air purification techniques, and present insights into the challenges facing the development of durable dropwise condensing surfaces.

Coherent Femtosecond Spectroscopy and Nonlinear Optical Imaging on the Nanoscale

Science.gov (United States)

Kravtsov, Vasily

Optical properties of many materials and macroscopic systems are defined by ultrafast dynamics of electronic, vibrational, and spin excitations localized on the nanoscale. Harnessing these excitations for material engineering, optical computing, and control of chemical reactions has been a long-standing goal in science and technology. However, it is challenging due to the lack of spectroscopic techniques that can resolve processes simultaneously on the nanometer spatial and femtosecond temporal scales. This thesis describes the fundamental principles, implementation, and experimental demonstration of a novel type of ultrafast microscopy based on the concept of adiabatic plasmonic nanofocusing. Simultaneous spatio-temporal resolution on a nanometer-femtosecond scale is achieved by using a near-field nonlinear optical response induced by ultrafast surface plasmon polaritons nanofocused on a metal tip. First, we study the surface plasmon response in metallic structures and evaluate its prospects and limitations for ultrafast near-field microscopy. Through plasmon emission-based spectroscopy, we investigate dephasing times and interplay between radiative and non-radiative decay rates of localized plasmons and their modification due to coupling. We identify a new regime of quantum plasmonic coupling, which limits the achievable spatial resolution to several angstroms but at the same time provides a potential channel for generating ultrafast electron currents at optical frequencies. Next, we study propagation of femtosecond wavepackets of surface plasmon polaritons on a metal tip. In time-domain interferometric measurements we detect group delays that correspond to slowing of the plasmon polaritons down to 20% of the speed of light at the tip apex. This provides direct experimental verification of the plasmonic nanofocusing mechanism and suggests enhanced nonlinear optical interactions at the tip apex. We then measure a plasmon-generated third-order nonlinear optical

Controllable nanoscale rotating actuator system based on carbon nanotube and graphene

International Nuclear Information System (INIS)

Huang, Jianzhang; Han, Qiang

2016-01-01

A controllable nanoscale rotating actuator system consisting of a double carbon nanotube and graphene driven by a temperature gradient is proposed, and its rotating dynamics performance and driving mechanism are investigated through molecular dynamics simulations. The outer tube exhibits stable pure rotation with certain orientation under temperature gradient and the steady rotational speed rises as the temperature gradient increases. It reveals that the driving torque is caused by the difference of atomic van der Waals potentials due to the temperature gradient and geometrical features of carbon nanotube. A theoretical model for driving torque is established based on lattice dynamics theory and its predicted results agree well with molecular dynamics simulations. Further discussion is taken according to the theoretical model. The work in this study would be a guide for design and application of controllable nanoscale rotating devices based on carbon nanotubes and graphene. (paper)

A study on a nano-scale materials simulation using a PC cluster

International Nuclear Information System (INIS)

Choi, Deok Kee; Ryu, Han Kyu

2002-01-01

Not a few scientists have paid attention to application of molecular dynamics to chemistry, biology and physics. With recent popularity of nano technology, nano-scale analysis has become a major subject in various engineering fields. A underlying nano scale analysis is based on classical molecular theories representing molecular dynamics. Based on Newton's law of motions of particles, the movement of each particles is to be determined by numerical integrations. As the size of computation is closely related with the number of molecules, materials simulation takes up huge amount of computer resources so that it is not until recent days that the application of molecular dynamics to materials simulations draw some attention from many researchers. Thanks to high-performance computers, materials simulation via molecular dynamics looks promising. In this study, a PC cluster consisting of multiple commodity PCs is established and nano scale materials simulations are carried out. Micro-sized crack propagation inside a nano material is displayed by the simulation

A surface evolution scheme to identify nanoscale intrinsic geometry from AFM experimental data

International Nuclear Information System (INIS)

Jang, Hong-Lae; Kim, Hyun-Seok; Park, Youmie; Cho, Seonho

2013-01-01

The geometrical properties of metallic nanoparticles such as the size and morphology have significant impacts on the structure and stability of the adsorbed biological entities as well as the nanoscale structural performances. To identify the nanoscale intrinsic geometry from the height images by atomic force microscopy (AFM), we developed a curvature-dependent evolution scheme that can eliminate the noise and smoothen the surfaces. The principal curvatures are computed directly from the first and second derivatives of the discrete AFM height data. The principal curvatures and directions correspond to the eigenvalues and eigenvectors of shape operator matrix, respectively. The evolution equation using the principal curvature flows smoothens the images in the corresponding principal directions. For an idealized model, κ 2 flow successfully identifies the major valley lines to represent the boundary of nanoparticles without referring to the phase information, whereas the mean curvature flow eliminates all the minor ones leaving only the major feature of the boundary. To demonstrate the capability of noise removal, smoothing surfaces, the identification of ridge and valley lines, and the extraction of intrinsic geometry, the developed numerical scheme is applied to real AFM data that include the silver nanoparticles of 24 nm diameter and the gold nanoparticles of 33–56 nm diameters

Nanoscale zero-valent iron impregnation of covalent organic polymer grafted activated carbon for water treatment

DEFF Research Database (Denmark)

Mines, Paul D.; Uthuppu, Basil; Thirion, Damien

2016-01-01

The use of nanoscale zero valent iron (nZVI) has quickly become a leading research material for the treatment of typically hard to degrade contaminants found in groundwater. These contaminants include antibiotics, pesticides, halogenated organics, heavy metals, among others. However, the effectiv......The use of nanoscale zero valent iron (nZVI) has quickly become a leading research material for the treatment of typically hard to degrade contaminants found in groundwater. These contaminants include antibiotics, pesticides, halogenated organics, heavy metals, among others. However...... polymeric network already previously proven to stabilize nZVI and a long-standing water treatment material,1 activated carbon; we have developed an advanced material that allows for the not only the stabilization of nZVI, but also the improved degradation of various water contaminants. This was done...... by performing a series of surface modification techniques to the surface of the activated carbon, then physically grafting the covalent organic polymer to the carbon in a shell-like manner, and ultimately synthesizing nZVI in situ within the pores of both the activated carbon and the polymeric network. Not only...

The Role of Membrane Curvature in Nanoscale Topography-Induced Intracellular Signaling.

Science.gov (United States)

Lou, Hsin-Ya; Zhao, Wenting; Zeng, Yongpeng; Cui, Bianxiao

2018-05-15

Over the past decade, there has been growing interest in developing biosensors and devices with nanoscale and vertical topography. Vertical nanostructures induce spontaneous cell engulfment, which enhances the cell-probe coupling efficiency and the sensitivity of biosensors. Although local membranes in contact with the nanostructures are found to be fully fluidic for lipid and membrane protein diffusions, cells appear to actively sense and respond to the surface topography presented by vertical nanostructures. For future development of biodevices, it is important to understand how cells interact with these nanostructures and how their presence modulates cellular function and activities. How cells recognize nanoscale surface topography has been an area of active research for two decades before the recent biosensor works. Extensive studies show that surface topographies in the range of tens to hundreds of nanometers can significantly affect cell functions, behaviors, and ultimately the cell fate. For example, titanium implants having rough surfaces are better for osteoblast attachment and host-implant integration than those with smooth surfaces. At the cellular level, nanoscale surface topography has been shown by a large number of studies to modulate cell attachment, activity, and differentiation. However, a mechanistic understanding of how cells interact and respond to nanoscale topographic features is still lacking. In this Account, we focus on some recent studies that support a new mechanism that local membrane curvature induced by nanoscale topography directly acts as a biochemical signal to induce intracellular signaling, which we refer to as the curvature hypothesis. The curvature hypothesis proposes that some intracellular proteins can recognize membrane curvatures of a certain range at the cell-to-material interface. These proteins then recruit and activate downstream components to modulate cell signaling and behavior. We discuss current technologies

Progress in nanoscale dry processes for fabrication of high-aspect-ratio features: How can we control critical dimension uniformity at the bottom?

Science.gov (United States)

Ishikawa, Kenji; Karahashi, Kazuhiro; Ishijima, Tatsuo; Cho, Sung Il; Elliott, Simon; Hausmann, Dennis; Mocuta, Dan; Wilson, Aaron; Kinoshita, Keizo

2018-06-01

In this review, we discuss the progress of emerging dry processes for nanoscale fabrication of high-aspect-ratio features, including emerging design technology for manufacturability. Experts in the fields of plasma processing have contributed to addressing the increasingly challenging demands of nanoscale deposition and etching technologies for high-aspect-ratio features. The discussion of our atomic-scale understanding of physicochemical reactions involving ion bombardment and neutral transport presents the major challenges shared across the plasma science and technology community. Focus is placed on advances in fabrication technology that control surface reactions on three-dimensional features, as well as state-of-the-art techniques used in semiconductor manufacturing with a brief summary of future challenges.

Controllable Nanoscale Inverted Pyramids for High-Efficient Quasi-Omnidirectional Crystalline Silicon Solar Cells.

Science.gov (United States)

Xu, Haiyuan; Zhong, Sihua; Zhuang, Yufeng; Shen, Wenzhong

2017-11-14

Nanoscale inverted pyramid structures (NIPs) have always been regarded as one of the most paramount light management schemes to achieve the extraordinary performance in various devices, especially in solar cells, due to their outstanding antireflection ability with relative lower surface enhancement ratio. However, the current approaches to fabricating the NIPs are complicated and not cost-effective for the massive cell production in the photovoltaic industry. Here, controllable NIPs are fabricated on crystalline silicon (c-Si) wafers by Ag catalyzed chemical etching and alkaline modification, which is a preferable all-solution-processed method. Through applying the NIPs to c-Si solar cells and optimizing the cell design, we have successfully achieved highly efficient NIPs textured solar cells with the champion efficiency of 20.5%. Importantly, the NIPs textured solar cells are further demonstrated to possess the quasi-omnidirectional property over the broad sunlight incident angles of approximately 0°-60°. Moreover, the NIPs are theoretically revealed to offer light trapping advantage for ultrathin c-Si solar cells. Hence, the NIPs formed by the controllable method exhibit a great potential to be used in the future photovoltaic industry as surface texture. © 2017 IOP Publishing Ltd.

Nanoscale control of energy and matter: challenges and opportunities for plasma science

International Nuclear Information System (INIS)

Ostrikov, Kostya

2013-01-01

Multidisciplinary challenges and opportunities in the ultimate ability to achieve nanoscale control of energy and matter are discussed using an example of the Plasma Nanoscience. This is an emerging multidisciplinary research field at the cutting edge of a large number of disciplines including but not limited to physics and chemistry of plasmas and gas discharges, materials science, surface science, nanoscience and nanotechnology, solid state physics, space physics and astrophysics, photonics, optics, plasmonics, spintronics, quantum information, physical chemistry, biomedical sciences and related engineering subjects. The origin, progress and future perspectives of this research field driven by the global scientific and societal challenges, is examined. The future potential of the Plasma Nanoscience to remain as a highly topical area in the global research and technological agenda in the Age of Fundamental-Level Control for a Sustainable Future is assessed using a framework of the five Grand Challenges for Basic Energy Sciences recently mapped by the US Department of Energy. It is concluded that the ongoing research is very relevant and is expected to substantially expand to competitively contribute to the solution of all of these Grand Challenges. The approach to control energy and matter at nano- and subnanoscales is based on identifying the prevailing carriers and transfer mechanisms of the energy and matter at the spatial and temporal scales that are most relevant to any particular nanofabrication process. Strong accent is made on the competitive edge of the plasma-based nanotechnology in applications related to the major socio-economic issues (energy, food, water, health and environment) that are crucial for a sustainable development of humankind. Several important emerging topics, opportunities and multidisciplinary synergies for the Plasma Nanoscience are highlighted. The main nanosafety issues are also discussed and the environment- and human health

High Performance Nano-Crystalline Oxide Fuel Cell Materials. Defects, Structures, Interfaces, Transport, and Electrochemistry

Energy Technology Data Exchange (ETDEWEB)

Barnett, Scott [Northwestern Univ., Evanston, IL (United States); Poeppelmeier, Ken [Northwestern Univ., Evanston, IL (United States); Mason, Tom [Northwestern Univ., Evanston, IL (United States); Marks, Lawrence [Northwestern Univ., Evanston, IL (United States); Voorhees, Peter [Northwestern Univ., Evanston, IL (United States)

2016-09-07

This project addresses fundamental materials challenges in solid oxide electrochemical cells, devices that have a broad range of important energy applications. Although nano-scale mixed ionically and electronically conducting (MIEC) materials provide an important opportunity to improve performance and reduce device operating temperature, durability issues threaten to limit their utility and have remained largely unexplored. Our work has focused on both (1) understanding the fundamental processes related to oxygen transport and surface-vapor reactions in nano-scale MIEC materials, and (2) determining and understanding the key factors that control their long-term stability. Furthermore, materials stability has been explored under the “extreme” conditions encountered in many solid oxide cell applications, i.e, very high or very low effective oxygen pressures, and high current density.

Nanoscale patterning of two metals on silicon surfaces using an ABC triblock copolymer template.

Science.gov (United States)

Aizawa, Masato; Buriak, Jillian M

2006-05-03

Patterning technologically important semiconductor interfaces with nanoscale metal films is important for applications such as metallic interconnects and sensing applications. Self-assembling block copolymer templates are utilized to pattern an aqueous metal reduction reaction, galvanic displacement, on silicon surfaces. Utilization of a triblock copolymer monolayer film, polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO), with two blocks capable of selective transport of different metal complexes to the surface (PEO and P2VP), allows for chemical discrimination and nanoscale patterning. Different regions of the self-assembled structure discriminate between metal complexes at the silicon surface, at which time they undergo the spontaneous reaction at the interface. Gold deposition from gold(III) compounds such as HAuCl4(aq) in the presence of hydrofluoric acid mirrors the parent block copolymer core structure, whereas silver deposition from Ag(I) salts such as AgNO3(aq) does the opposite, localizing exclusively under the corona. By carrying out gold deposition first and silver second, sub-100-nm gold features surrounded by silver films can be produced. The chemical selectivity was extended to other metals, including copper, palladium, and platinum. The interfaces were characterized by a variety of methods, including scanning electron microscopy, scanning Auger microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy.

Osteogenic response of human mesenchymal stem cells to well-defined nanoscale topography in vitro

Directory of Open Access Journals (Sweden)

de Peppo GM

2014-05-01

Full Text Available Giuseppe Maria de Peppo,1–3 Hossein Agheli,2,3 Camilla Karlsson,2,3 Karin Ekström,2,3 Helena Brisby,3,4 Maria Lennerås,2,3 Stefan Gustafsson,3,5 Peter Sjövall,3,5,6 Anna Johansson,2,3 Eva Olsson,3,5 Jukka Lausmaa,3,6 Peter Thomsen,2,3 Sarunas Petronis3,6 1The New York Stem Cell Foundation Research Institute, New York, NY, USA; 2Department of Biomaterials, Sahlgrenska Academy, University of Gothenburg, 3BIOMATCELL VINN Excellence Center of Biomaterials and Cell Therapy, 4Department of Orthopaedics, Sahlgrenska Academy, University of Gothenburg, 5Applied Physics, Chalmers University of Technology, Göteborg, Sweden; 6Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden, Borås, Sweden Background: Patterning medical devices at the nanoscale level enables the manipulation of cell behavior and tissue regeneration, with topographic features recognized as playing a significant role in the osseointegration of implantable devices. Methods: In this study, we assessed the ability of titanium-coated hemisphere-like topographic nanostructures of different sizes (approximately 50, 100, and 200 nm to influence the morphology, proliferation, and osteogenic differentiation of human mesenchymal stem cells (hMSCs. Results: We found that the proliferation and osteogenic differentiation of hMSCs was influenced by the size of the underlying structures, suggesting that size variations in topographic features at the nanoscale level, independently of chemistry, can be exploited to control hMSC behavior in a size-dependent fashion. Conclusion: Our studies demonstrate that colloidal lithography, in combination with coating technologies, can be exploited to investigate the cell response to well defined nanoscale topography and to develop next-generation surfaces that guide tissue regeneration and promote implant integration. Keywords: colloidal lithography, nanotopography, human mesenchymal stem cells, cell proliferation, osteogenic

Spintronics in nanoscale devices

CERN Document Server

Hedin, Eric R

2013-01-01

By exploiting the novel properties of quantum dots and nanoscale Aharonov-Bohm rings together with the electronic and magnetic properties of various semiconductor materials and graphene, researchers have conducted numerous theoretical and computational modeling studies and experimental tests that show promising behavior for spintronics applications. Spin polarization and spin-filtering capabilities and the ability to manipulate the electron spin state through external magnetic or electric fields have demonstrated the promise of workable nanoscale devices for computing and memory applications.

Controlling coverage of solution cast materials with unfavourable surface interactions

KAUST Repository

Burlakov, V. M.; Eperon, G. E.; Snaith, H. J.; Chapman, S. J.; Goriely, A.

2014-01-01

Creating uniform coatings of a solution-cast material is of central importance to a broad range of applications. Here, a robust and generic theoretical framework for calculating surface coverage by a solid film of material de-wetting a substrate is presented. Using experimental data from semiconductor thin films as an example, we calculate surface coverage for a wide range of annealing temperatures and film thicknesses. The model generally predicts that for each value of the annealing temperature there is a range of film thicknesses leading to poor surface coverage. The model accurately reproduces solution-cast thin film coverage for organometal halide perovskites, key modern photovoltaic materials, and identifies processing windows for both high and low levels of surface coverage. © 2014 AIP Publishing LLC.

Controlling coverage of solution cast materials with unfavourable surface interactions

KAUST Repository

Burlakov, V. M.

2014-03-03

Creating uniform coatings of a solution-cast material is of central importance to a broad range of applications. Here, a robust and generic theoretical framework for calculating surface coverage by a solid film of material de-wetting a substrate is presented. Using experimental data from semiconductor thin films as an example, we calculate surface coverage for a wide range of annealing temperatures and film thicknesses. The model generally predicts that for each value of the annealing temperature there is a range of film thicknesses leading to poor surface coverage. The model accurately reproduces solution-cast thin film coverage for organometal halide perovskites, key modern photovoltaic materials, and identifies processing windows for both high and low levels of surface coverage. © 2014 AIP Publishing LLC.

Enhanced nanoscale friction on fluorinated graphene.

Science.gov (United States)

Kwon, Sangku; Ko, Jae-Hyeon; Jeon, Ki-Joon; Kim, Yong-Hyun; Park, Jeong Young

2012-12-12

Atomically thin graphene is an ideal model system for studying nanoscale friction due to its intrinsic two-dimensional (2D) anisotropy. Furthermore, modulating its tribological properties could be an important milestone for graphene-based micro- and nanomechanical devices. Here, we report unexpectedly enhanced nanoscale friction on chemically modified graphene and a relevant theoretical analysis associated with flexural phonons. Ultrahigh vacuum friction force microscopy measurements show that nanoscale friction on the graphene surface increases by a factor of 6 after fluorination of the surface, while the adhesion force is slightly reduced. Density functional theory calculations show that the out-of-plane bending stiffness of graphene increases up to 4-fold after fluorination. Thus, the less compliant F-graphene exhibits more friction. This indicates that the mechanics of tip-to-graphene nanoscale friction would be characteristically different from that of conventional solid-on-solid contact and would be dominated by the out-of-plane bending stiffness of the chemically modified graphene. We propose that damping via flexural phonons could be a main source for frictional energy dissipation in 2D systems such as graphene.

Programming the Assembly of Unnatural Materials with Nucleic Acids

Science.gov (United States)

Mirkin, Chad

Nature directs the assembly of enormously complex and highly functional materials through an encoded class of biomolecules, nucleic acids. The establishment of a similarly programmable code for the construction of synthetic, unnatural materials would allow researchers to impart functionality by precisely positioning all material components. Although it is exceedingly difficult to control the complex interactions between atomic and molecular species in such a manner, interactions between nanoscale components can be directed through the ligands attached to their surface. Our group has shown that nucleic acids can be used as highly programmable surface ligands to control the spacing and symmetry of nanoparticle building blocks in structurally sophisticated and functional materials. These nucleic acids function as programmable ``bonds'' between nanoparticle ``atoms,'' analogous to a nanoscale genetic code for assembling materials. The sequence and length tunability of nucleic acid bonds has allowed us to define a powerful set of design rules for the construction of nanoparticle superlattices with more than 30 unique lattice symmetries, tunable defect structures and interparticle spacings, and several well-defined crystal habits. Further, the nature of the nucleic acid bond enables an additional level of structural control: temporal regulation of dynamic material response to external biomolecular and chemical stimuli. This control allows for the reversible transformation between thermodynamic states with different crystal symmetries, particle stoichiometries, thermal stabilities, and interparticle spacings on demand. Notably, our unique genetic approach affords functional nanoparticle architectures that, among many other applications, can be used to systematically explore and manipulate optoelectronic material properties, such as tunable interparticle plasmonic interactions, microstructure-directed energy emission, and coupled plasmonic and photonic modes.

Decreased bacterial growth on titanium nanoscale topographies created by ion beam assisted evaporation

Directory of Open Access Journals (Sweden)

Stolzoff M

2017-02-01

Full Text Available Michelle Stolzoff,1 Jason E Burns,2 Arash Aslani,2 Eric J Tobin,2 Congtin Nguyen,1 Nicholas De La Torre,3 Negar H Golshan,3 Katherine S Ziemer,3 Thomas J Webster1,3,4 1Department of Bioengineering, Northeastern University, Boston, 2N2 Biomedical, Bedford, MA, 3Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 4Center of Excellence for Advanced Materials Research, University of King Abdulaziz, Jeddah, Saudi Arabia Abstract: Titanium is one of the most widely used materials for orthopedic implants, yet it has exhibited significant complications in the short and long term, largely resulting from poor cell–material interactions. Among these many modes of failure, bacterial infection at the site of implantation has become a greater concern with the rise of antibiotic-resistant bacteria. Nanostructured surfaces have been found to prevent bacterial colonization on many surfaces, including nanotextured titanium. In many cases, specific nanoscale roughness values and resulting surface energies have been considered to be “bactericidal”; here, we explore the use of ion beam evaporation as a novel technique to create nanoscale topographical features that can reduce bacterial density. Specifically, we investigated the relationship between the roughness and titanium nanofeature shapes and sizes, in which smaller, more regularly spaced nanofeatures (specifically 40–50 nm tall peaks spaced ~0.25 µm apart were found to have more effect than surfaces with high roughness values alone. Keywords: titanium, nanostructures, bacteria, bone ingrowth, surface roughness, IBAD 

Nanoscale definition of substrate materials to direct human adult stem cells towards tissue specific populations.

Science.gov (United States)

Curran, Judith M; Chen, Rui; Stokes, Robert; Irvine, Eleanor; Graham, Duncan; Gubbins, Earl; Delaney, Deany; Amro, Nabil; Sanedrin, Raymond; Jamil, Haris; Hunt, John A

2010-03-01

The development of homogenously nano-patterned chemically modified surfaces that can be used to initiate a cellular response, particularly stem cell differentiation, in a highly controlled manner without the need for exogenous biological factors has never been reported, due to that fact that precisely defined and reproducible systems have not been available that can be used to study cell/material interactions and unlock the potential of a material driven cell response. Until now material driven stem cell (furthermore any cell) responses have been variable due to the limitations in definition and reproducibility of the underlying substrate and the lack of true homogeneity of modifications that can dictate a cellular response at a sub-micron level that can effectively control initial cell interactions of all cells that contact the surface. Here we report the successful design and use of homogenously molecularly nanopatterned surfaces to control initial stem cell adhesion and hence function. The highly specified nano-patterned arrays were compared directly to silane modified bulk coated substrates that have previously been proven to initiate mesenchymal stem cell (MSC) differentiation in a heterogenous manner, the aim of this study was to prove the efficiency of these previously observed cell responses could be enhanced by the incorporation of nano-patterns. Nano-patterned surfaces were prepared by Dip Pen Nanolithography (DPN) to produce arrays of 70 nm sized dots separated by defined spacings of 140, 280 and 1000 nm with terminal functionalities of carboxyl, amino, methyl and hydroxyl and used to control cell growth. These nanopatterned surfaces exhibited unprecedented control of initial cell interactions and will change the capabilities for stem cell definition in vitro and then cell based medical therapies. In addition to highlighting the ability of the materials to control stem cell functionality on an unprecedented scale this research also introduces the

Nanoscale reference materials for environmental, health and safety measurements: needs, gaps and opportunities.

Science.gov (United States)

Stefaniak, Aleksandr B; Hackley, Vincent A; Roebben, Gert; Ehara, Kensei; Hankin, Steve; Postek, Michael T; Lynch, Iseult; Fu, Wei-En; Linsinger, Thomas P J; Thünemann, Andreas F

2013-12-01

The authors critically reviewed published lists of nano-objects and their physico-chemical properties deemed important for risk assessment and discussed metrological challenges associated with the development of nanoscale reference materials (RMs). Five lists were identified that contained 25 (classes of) nano-objects; only four (gold, silicon dioxide, silver, titanium dioxide) appeared on all lists. Twenty-three properties were identified for characterisation; only (specific) surface area appeared on all lists. The key themes that emerged from this review were: 1) various groups have prioritised nano-objects for development as "candidate RMs" with limited consensus; 2) a lack of harmonised terminology hinders accurate description of many nano-object properties; 3) many properties identified for characterisation are ill-defined or qualitative and hence are not metrologically traceable; 4) standardised protocols are critically needed for characterisation of nano-objects as delivered in relevant media and as administered to toxicological models; 5) the measurement processes being used to characterise a nano-object must be understood because instruments may measure a given sample in a different way; 6) appropriate RMs should be used for both accurate instrument calibration and for more general testing purposes (e.g., protocol validation); 7) there is a need to clarify that where RMs are not available, if "(representative) test materials" that lack reference or certified values may be useful for toxicology testing and 8) there is a need for consensus building within the nanotechnology and environmental, health and safety communities to prioritise RM needs and better define the required properties and (physical or chemical) forms of the candidate materials.

Sub-nanoscale surface ruggedness provides a water-tight seal for exposed regions in soluble protein structure.

Directory of Open Access Journals (Sweden)

Erica Schulz

2010-09-01

Full Text Available Soluble proteins must maintain backbone hydrogen bonds (BHBs water-tight to ensure structural integrity. This protection is often achieved by burying the BHBs or wrapping them through intermolecular associations. On the other hand, water has low coordination resilience, with loss of hydrogen-bonding partnerships carrying significant thermodynamic cost. Thus, a core problem in structural biology is whether natural design actually exploits the water coordination stiffness to seal the backbone in regions that are exposed to the solvent. This work explores the molecular design features that make this type of seal operative, focusing on the side-chain arrangements that shield the protein backbone. We show that an efficient sealing is achieved by adapting the sub-nanoscale surface topography to the stringency of water coordination: an exposed BHB may be kept dry if the local concave curvature is small enough to impede formation of the coordination shell of a penetrating water molecule. Examination of an exhaustive database of uncomplexed proteins reveals that exposed BHBs invariably occur within such sub-nanoscale cavities in native folds, while this level of local ruggedness is absent in other regions. By contrast, BHB exposure in misfolded proteins occurs with larger local curvature promoting backbone hydration and consequently, structure disruption. These findings unravel physical constraints fitting a spatially dependent least-action for water coordination, introduce a molecular design concept, and herald the advent of water-tight peptide-based materials with sufficient backbone exposure to remain flexible.

Nanoscale Electrochemistry of sp(2) Carbon Materials: From Graphite and Graphene to Carbon Nanotubes.

Science.gov (United States)

Unwin, Patrick R; Güell, Aleix G; Zhang, Guohui

2016-09-20

-sphere redox processes. (ii) Demonstration of the high activity of basal plane HOPG toward other reactions, with no requirement for catalysis by step edges or defects, as exemplified by studies of proton-coupled electron transfer, redox transformations of adsorbed molecules, surface functionalization via diazonium electrochemistry, and metal electrodeposition. (iii) Rationalization of the complex interplay of different factors that determine electrochemistry at graphene, including the source (mechanical exfoliation from graphite vs chemical vapor deposition), number of graphene layers, edges, electronic structure, redox couple, and electrode history effects. (iv) New methodologies that allow nanoscale electrochemistry of 1D materials (SWNTs) to be related to their electronic characteristics (metallic vs semiconductor SWNTs), size, and quality, with high resolution imaging revealing the high activity of SWNT sidewalls and the importance of defects for some electrocatalytic reactions (e.g., the oxygen reduction reaction). The experimental approaches highlighted for carbon electrodes are generally applicable to other electrode materials and set a new framework and course for the study of electrochemical and interfacial processes.

Nanoscale thermal transport. II. 2003–2012

International Nuclear Information System (INIS)

Cahill, David G.; Braun, Paul V.; Chen, Gang; Clarke, David R.; Fan, Shanhui; Goodson, Kenneth E.; Keblinski, Pawel; King, William P.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Phillpot, Simon R.; Pop, Eric; Shi, Li

2014-01-01

A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ∼1 nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and

A hard X-ray nanoprobe beamline for nanoscale microscopy

Energy Technology Data Exchange (ETDEWEB)

Winarski, Robert P., E-mail: winarski@anl.gov; Holt, Martin V. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60441 (United States); Rose, Volker [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60441 (United States); Fuesz, Peter; Carbaugh, Dean; Benson, Christa; Shu, Deming; Kline, David; Stephenson, G. Brian; McNulty, Ian [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60441 (United States); Maser, Jörg [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60441 (United States)

2012-11-01

The Hard X-ray Nanoprobe Beamline is a precision platform for scanning probe and full-field microscopy with 3–30 keV X-rays. A combination of high-stability X-ray optics and precision motion sensing and control enables detailed studies of the internal features of samples with resolutions approaching 30 nm. The Hard X-ray Nanoprobe Beamline (or Nanoprobe Beamline) is an X-ray microscopy facility incorporating diffraction, fluorescence and full-field imaging capabilities designed and operated by the Center for Nanoscale Materials and the Advanced Photon Source at Sector 26 of the Advanced Photon Source at Argonne National Laboratory. This facility was constructed to probe the nanoscale structure of biological, environmental and material sciences samples. The beamline provides intense focused X-rays to the Hard X-ray Nanoprobe (or Nanoprobe) which incorporates Fresnel zone plate optics and a precision laser sensing and control system. The beamline operates over X-ray energies from 3 to 30 keV, enabling studies of most elements in the periodic table, with a particular emphasis on imaging transition metals.

Chemistry and Materials Science progress report, first half FY 1992

International Nuclear Information System (INIS)

1992-07-01

This report contains sections on: Fundamentals of the physics and processing of metals; interfaces, adhesion, and bonding; energetic materials; plutonium research; synchrotron radiation-based materials science; atomistic approach to the interaction of surfaces with the environment: actinide studies; properties of carbon fibers; buried layer formation using ion implantation; active coherent control of chemical reaction dynamics; inorganic and organic aerogels; synthesis and characterization of melamine-formaldehyde aerogels; structural transformation and precursor phenomena in advanced materials; magnetic ultrathin films, surfaces, and overlayers; ductile-phase toughening of refractory-metal intermetallics; particle-solid interactions; electronic structure evolution of metal clusters; and nanoscale lithography induced chemically or physically by modified scanned probe microscopy

Nanoscale biomemory composed of recombinant azurin on a nanogap electrode

International Nuclear Information System (INIS)

Chung, Yong-Ho; Lee, Taek; Choi, Jeong-Woo; Park, Hyung Ju; Yun, Wan Soo; Min, Junhong

2013-01-01

We fabricate a nanoscale biomemory device composed of recombinant azurin on nanogap electrodes. For this, size-controllable nanogap electrodes are fabricated by photolithography, electron beam lithography, and surface catalyzed chemical deposition. Moreover, we investigate the effect of gap distance to optimize the size of electrodes for a biomemory device and explore the mechanism of electron transfer from immobilized protein to a nanogap counter-electrode. As the distance of the nanogap electrode is decreased in the nanoscale, the absolute current intensity decreases according to the distance decrement between the electrodes due to direct electron transfer, in contrast with the diffusion phenomenon of a micro-electrode. The biomemory function is achieved on the optimized nanogap electrode. These results demonstrate that the fabricated nanodevice composed of a nanogap electrode and biomaterials provides various advantages such as quantitative control of signals and exclusion of environmental effects such as noise. The proposed bioelectronics device, which could be mass-produced easily, could be applied to construct a nanoscale bioelectronics system composed of a single biomolecule. (paper)

Viscoelastic nanoscale properties of cuticle contribute to the high-pass properties of spider vibration receptor (Cupiennius salei Keys)

OpenAIRE

McConney, Michael E; Schaber, Clemens F; Julian, Michael D; Barth, Friedrich G; Tsukruk, Vladimir V

2007-01-01

Atomic force microscopy (AFM) and surface force spectroscopy were applied in live spiders to their joint pad material located distal of the metatarsal lyriform organs, which are highly sensitive vibration sensors. The surface topography of the material is sufficiently smooth to probe the local nanomechanical properties with nanometre elastic deflections. Nanoscale loads were applied in the proximad direction on the distal joint region simulating the natural stimulus situation. The force curve...

Contributions of chemical and mechanical surface properties and temperature effect on the adhesion at the nanoscale

International Nuclear Information System (INIS)

Awada, Houssein; Noel, Olivier; Hamieh, Tayssir; Kazzi, Yolla; Brogly, Maurice

2011-01-01

The atomic force microscope (AFM) is a powerful tool to investigate surface properties of model systems at the nanoscale. However, to get semi-quantitative and reproducible data with the AFM, it is necessary to establish a rigorous experimental procedure. In particular, a systematic calibration procedure of AFM measurements is necessary before producing reliable semi-quantitative data. In this paper, we study the contributions of the chemical and mechanical surface properties or the temperature influence on the adhesion energy at a local scale. To reach this objective, two types of model systems were considered. The first one is composed of rigid substrates (silicon wafers or AFM tips covered with gold) which were chemically modified by molecular self-assembling monolayers to display different surface properties (methyl and hydroxyl functional groups). The second one consists of model polymer networks (cross-linked polydimethylsiloxane) of variable mechanical properties. The comparison of the force curves obtained from the two model systems shows that the viscoelastic contributions dominate for the adhesion with polymer substrates, whereas, chemical contributions dominate for the rigid substrates. The temperature effect on the adhesion energy is also reported. Finally, we propose a relation for the adhesion energy at the nanoscale. This relation relates the energy measured during the separation of the contact to the three parameters: the surface properties of the polymer, the energy dissipated within the contact zone and the temperature.

Controlled manipulation of oxygen vacancies using nanoscale flexoelectricity

Energy Technology Data Exchange (ETDEWEB)

Das, Saikat [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Wang, Bo [Pennsylvania State Univ., University Park, PA (United States).Dept. of Materials Science and Engineering; Cao, Ye [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Inst. for; Rae Cho, Myung [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Jae Shin, Yeong [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Mo Yang, Sang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Sookmyung Women' s Univ., Seoul (Republic of Korea). Dept. of Physics; Wang, Lingfei [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Kim, Minu [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Kalinin, Sergei V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Inst. for Functional Imaging of Materials; Chen, Long-Qing [Pennsylvania State Univ., University Park, PA (United States).Dept. of Materials Science and Engineering; Noh, Tae Won [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy

2017-09-20

Oxygen vacancies, especially their distribution, are directly coupled to the electromagnetic properties of oxides and related emergent functionalities that have implications for device applications. Here using a homoepitaxial strontium titanate thin film, we demonstrate a controlled manipulation of the oxygen vacancy distribution using the mechanical force from a scanning probe microscope tip. By combining Kelvin probe force microscopy imaging and phase-field simulations, we show that oxygen vacancies can move under a stress-gradient-induced depolarisation field. When tailored, this nanoscale flexoelectric effect enables a controlled spatial modulation. In motion, the scanning probe tip thereby deterministically reconfigures the spatial distribution of vacancies. Finally, the ability to locally manipulate oxygen vacancies on-demand provides a tool for the exploration of mesoscale quantum phenomena and engineering multifunctional oxide devices.

Nanoscale volcanoes: accretion of matter at ion-sculpted nanopores.

Science.gov (United States)

Mitsui, Toshiyuki; Stein, Derek; Kim, Young-Rok; Hoogerheide, David; Golovchenko, J A

2006-01-27

We demonstrate the formation of nanoscale volcano-like structures induced by ion-beam irradiation of nanoscale pores in freestanding silicon nitride membranes. Accreted matter is delivered to the volcanoes from micrometer distances along the surface. Volcano formation accompanies nanopore shrinking and depends on geometrical factors and the presence of a conducting layer on the membrane's back surface. We argue that surface electric fields play an important role in accounting for the experimental observations.

Friction laws at the nanoscale.

Science.gov (United States)

Mo, Yifei; Turner, Kevin T; Szlufarska, Izabela

2009-02-26

Macroscopic laws of friction do not generally apply to nanoscale contacts. Although continuum mechanics models have been predicted to break down at the nanoscale, they continue to be applied for lack of a better theory. An understanding of how friction force depends on applied load and contact area at these scales is essential for the design of miniaturized devices with optimal mechanical performance. Here we use large-scale molecular dynamics simulations with realistic force fields to establish friction laws in dry nanoscale contacts. We show that friction force depends linearly on the number of atoms that chemically interact across the contact. By defining the contact area as being proportional to this number of interacting atoms, we show that the macroscopically observed linear relationship between friction force and contact area can be extended to the nanoscale. Our model predicts that as the adhesion between the contacting surfaces is reduced, a transition takes place from nonlinear to linear dependence of friction force on load. This transition is consistent with the results of several nanoscale friction experiments. We demonstrate that the breakdown of continuum mechanics can be understood as a result of the rough (multi-asperity) nature of the contact, and show that roughness theories of friction can be applied at the nanoscale.

Organic molecules as tools to control the growth, surface structure, and redox activity of colloidal quantum dots.

Science.gov (United States)

Weiss, Emily A

2013-11-19

In order to achieve efficient and reliable technology that can harness solar energy, the behavior of electrons and energy at interfaces between different types or phases of materials must be understood. Conversion of light to chemical or electrical potential in condensed phase systems requires gradients in free energy that allow the movement of energy or charge carriers and facilitate redox reactions and dissociation of photoexcited states (excitons) into free charge carriers. Such free energy gradients are present at interfaces between solid and liquid phases or between inorganic and organic materials. Nanostructured materials have a higher density of these interfaces than bulk materials. Nanostructured materials, however, have a structural and chemical complexity that does not exist in bulk materials, which presents a difficult challenge: to lower or eliminate energy barriers to electron and energy flux that inevitably result from forcing different materials to meet in a spatial region of atomic dimensions. Chemical functionalization of nanostructured materials is perhaps the most versatile and powerful strategy for controlling the potential energy landscape of their interfaces and for minimizing losses in energy conversion efficiency due to interfacial structural and electronic defects. Colloidal quantum dots are semiconductor nanocrystals synthesized with wet-chemical methods and coated in organic molecules. Chemists can use these model systems to study the effects of chemical functionalization of nanoscale organic/inorganic interfaces on the optical and electronic properties of a nanostructured material, and the behavior of electrons and energy at interfaces. The optical and electronic properties of colloidal quantum dots have an intense sensitivity to their surface chemistry, and their organic adlayers make them dispersible in solvent. This allows researchers to use high signal-to-noise solution-phase spectroscopy to study processes at interfaces. In this

A molecular dynamics investigation into the mechanisms of subsurface damage and material removal of monocrystalline copper subjected to nanoscale high speed grinding

International Nuclear Information System (INIS)

Li, Jia; Fang, Qihong; Liu, Youwen; Zhang, Liangchi

2014-01-01

This paper investigates the mechanisms of subsurface damage and material removal of monocrystalline copper when it is under a nanoscale high speed grinding of a diamond tip. The analysis was carried out with the aid of three-dimensional molecular dynamics simulations. The key factors that would influence the deformation of the material were carefully explored by analyzing the chip, dislocation movement, and workpiece deformation, which include grinding speed, depth of cut, grid tip radius, crystal orientation and machining angle of copper. An analytical model was also established to predict the emission of partial dislocations during the nanoscale high speed grinding. The investigation showed that a higher grinding velocity, a larger tip radius or a larger depth of cut would result in a larger chipping volume and a greater temperature rise in the copper workpiece. A lower grinding velocity would produce more intrinsic stacking faults. It was also found that the transition of deformation mechanisms depends on the competition between the dislocations and deformation twinning. There is a critical machining angle, at which a higher velocity, a smaller tip radius, or a smaller depth of cut will reduce the subsurface damage and improve the smoothness of a ground surface. The established analytical model showed that the Shockley dislocation emission is most likely to occur with the crystal orientations of (0 0 1)[1 0 0] at 45° angle.

The Role of Isolation Methods on a Nanoscale Surface Structure and Its Effect on the Size of Exosomes

Directory of Open Access Journals (Sweden)

JungReem Woo

2016-06-01

Full Text Available Exosomes are ~100 nanometre diameter vesicles secreted by mammalian cells. These emerging disease biomarkers carry nucleic acids, proteins and lipids specific to the parental cells that secrete them. Exosomes are typically isolated in bulk by ultracentrifugation, filtration or immu‐ noaffinity precipitation for downstream proteomic, genomic, or lipidomic analysis. However, the structural properties and heterogeneity of isolated exosomes at the single vesicle level are not well characterized due to their small size. In this paper, by using high-resolution atomic force microscope imaging, we show the nanoscale mor‐ phology and structural heterogeneity in exosomes derived from U87 cells. Quantitative assessment of single exosomes reveals nanoscale variations in morphology, surface roughness and counts isolated by ultracentrifugation (UC and immunoaffinity (IA purification. Both methods produce intact globular, 30-120 nm sized vesicles when imaged under fluid and in air. However, IA exosomes had higher surface roughness and bimodal size population compared to UC exosomes. The study highlights the differences in size and surface topography of exosomes purified from a single cell type using different isolation methods.

Field limit and nano-scale surface topography of superconducting radio-frequency cavity made of extreme type II superconductor

OpenAIRE

Kubo, Takayuki

2014-01-01

The field limit of superconducting radio-frequency cavity made of type II superconductor with a large Ginzburg-Landau parameter is studied with taking effects of nano-scale surface topography into account. If the surface is ideally flat, the field limit is imposed by the superheating field. On the surface of cavity, however, nano-defects almost continuously distribute and suppress the superheating field everywhere. The field limit is imposed by an effective superheating field given by the pro...

Physical controls on directed virus assembly at nanoscale chemical templates

International Nuclear Information System (INIS)

Cheung, C L; Chung, S; Chatterji, A; Lin, T; Johnson, J E; Hok, S; Perkins, J; De Yoreo, J

2006-01-01

Viruses are attractive building blocks for nanoscale heterostructures, but little is understood about the physical principles governing their directed assembly. In-situ force microscopy was used to investigate organization of Cowpea Mosaic Virus engineered to bind specifically and reversibly at nanoscale chemical templates with sub-30nm features. Morphological evolution and assembly kinetics were measured as virus flux and inter-viral potential were varied. The resulting morphologies were similar to those of atomic-scale epitaxial systems, but the underlying thermodynamics was analogous to that of colloidal systems in confined geometries. The 1D templates biased the location of initial cluster formation, introduced asymmetric sticking probabilities, and drove 1D and 2D condensation at subcritical volume fractions. The growth kinetics followed a t 1/2 law controlled by the slow diffusion of viruses. The lateral expansion of virus clusters that initially form on the 1D templates following introduction of polyethylene glycol (PEG) into the solution suggests a significant role for weak interaction

The control of human mesenchymal cell differentiation using nanoscale symmetry and disorder

Science.gov (United States)

Dalby, Matthew J.; Gadegaard, Nikolaj; Tare, Rahul; Andar, Abhay; Riehle, Mathis O.; Herzyk, Pawel; Wilkinson, Chris D. W.; Oreffo, Richard O. C.

2007-12-01

A key tenet of bone tissue engineering is the development of scaffold materials that can stimulate stem cell differentiation in the absence of chemical treatment to become osteoblasts without compromising material properties. At present, conventional implant materials fail owing to encapsulation by soft tissue, rather than direct bone bonding. Here, we demonstrate the use of nanoscale disorder to stimulate human mesenchymal stem cells (MSCs) to produce bone mineral in vitro, in the absence of osteogenic supplements. This approach has similar efficiency to that of cells cultured with osteogenic media. In addition, the current studies show that topographically treated MSCs have a distinct differentiation profile compared with those treated with osteogenic media, which has implications for cell therapies.

Controlling friction in a manganite surface by resistive switching

OpenAIRE

Schmidt, Hendrik; Krisponeit, Jon-Olaf; Samwer, Konrad; Volkert, Cynthia A.

2016-01-01

We report a significant change in friction of a $\\rm La_{0.55}Ca_{0.45}MnO_3$ thin film measured as a function of the materials resistive state under ultrahigh vacuum conditions at room temperature by friction force microscopy. While friction is high in the insulating state, it clearly changes to lower values if the probed local region is switched to the conducting state via nanoscale resistance switching. Thus we demonstrate active control of friction without having to change the temperature...

Direct optical imaging of nanoscale internal organization of polymer films

Science.gov (United States)

Suran, Swathi; Varma, Manoj

2018-02-01

Owing to its sensitivity and precise control at the nanoscale, polyelectrolytes have been immensely used to modify surfaces. Polyelectrolyte multilayers are generally water made and are easy to fabricate on any surface by the layer-by-layer (LbL) self-assembly process due to electrostatic interactions. Polyelectrolyte multilayers or PEMs can be assembled to form ultrathin membranes which can have potential applications in water filtration and desalination [1-3]. Hydration in PEMs is a consequence of both the bulk and surface phenomenon [4-7]. Bulk behavior of polymer membranes are well understood. Several techniques including reflectivity and contact angle measurements were used to measure the hydration in the bulk of polymer membranes [4, 8]. On the other hand their internal organization at the molecular level which can have a profound contribution in the transport mechanism, are not understood well. Previously, we engineered a technique, which we refer to as Bright-field Nanoscopy, which allows nanoscale optical imaging using local heterogeneities in a water-soluble germanium (Ge) thin film ( 25 nm thick) deposited on gold [8]. We use this technique to study the water transport in PEMs. It is understood that the surface charge and outer layers of the PEMs play a significant role in water transport through polymers [9-11]. This well-known `odd-even' effect arising on having different surface termination of the PEMs was optically observed with a spatial resolution unlike any other reported previously [12]. In this communication, we report that on increasing the etchant's concentration, one can control the lateral etching of the Ge film. This allowed the visualization of the nanoscale internal organization in the PEMs. Knowledge of the internal structure would allow one to engineer polymer membranes specific to applications such as drug delivering capsules, ion transport membranes and barriers etc. We also demonstrate a mathematical model involving a surface

Tip-Enhanced Nano-Spectroscopy, Imaging, and Control: From Single Molecules to van der Waals Materials

Science.gov (United States)

Park, Kyoung-Duck

near-field probe. We reveal nanoscale correlations between surface biomolecules and intracellular organelle structures through near-field imaging of the spatial distribution of EGFRs on the membrane of A431 cancer cells. In addition, to understand modified spontaneous emission properties of single quantum dots coupled strongly with localized plasmon, we perform tip-enhanced photoluminescence (TEPL) spectroscopy of the single CdSe/ZnS quantum dots on gold film. We probe and control nanoscale processes in van der Waals two-dimensional (2D) materials. To understand lattice and electronic structure as well as elastic and phonon scattering properties of grain boundaries (GBs) in large-area graphene, we perform TERS imaging. Through correlated analysis of multispectral TERS images with corresponding topography and near-field scattering image, we reveal bilayer structure of GBs in the form of twisted stacking. In addition, we determine the misorientation angles of the bilayer GBs from a detailed quantitative investigation of the Raman modes. In addition, we present a new hybrid nano-optomechanical tip-enhanced spectroscopy and imaging approach combining TERS, TEPL, and atomic force local strain manipulation to probe the heterogeneous PL responses at nanoscale defects and control the local bandgap in transition metal dichalcogenide (TMD) monolayer. We further extend this approach to probe and control the radiative emission of dark excitons and localized excitons. Based on nano-tip enhanced spectroscopy with 600,000-fold PL enhancement induced by the plasmonic Purcell effect and few-fs radiative dynamics of the optical antenna tip, we can directly probe and actively modulate the dark exciton and localized exciton emissions in time ( ms) and space (<15 nm) at room temperature. Lastly, to extend the range of tip-enhanced microscopy applications to nano-crystallography and nonlinear optics, we present a generalizable approach controlling the excitation polarizability for both in

Fabrication of Superhydrophobic Surfaces with Controllable Electrical Conductivity and Water Adhesion.

Science.gov (United States)

Ye, Lijun; Guan, Jipeng; Li, Zhixiang; Zhao, Jingxin; Ye, Cuicui; You, Jichun; Li, Yongjin

2017-02-14

A facile and versatile strategy for fabricating superhydrophobic surfaces with controllable electrical conductivity and water adhesion is reported. "Vine-on-fence"-structured and cerebral cortex-like superhydrophobic surfaces are constructed by filtering a suspension of multiwalled carbon nanotubes (MWCNTs), using polyoxymethylene nonwovens as the filter paper. The nonwovens with micro- and nanoporous two-tier structures act as the skeleton, introducing a microscale structure. The MWCNTs act as nanoscale structures, creating hierarchical surface roughness. The surface topography and the electrical conductivity of the superhydrophobic surfaces are controlled by varying the MWCNT loading. The vine-on-fence-structured surfaces exhibit "sticky" superhydrophobicity with high water adhesion. The cerebral cortex-like surfaces exhibit self-cleaning properties with low water adhesion. The as-prepared superhydrophobic surfaces are chemically resistant to acidic and alkaline environments of pH 2-12. They therefore have potential in applications such as droplet-based microreactors and thin-film microextraction. These findings aid our understanding of the role that surface topography plays in the design and fabrication of superhydrophobic surfaces with different water-adhesion properties.

Nanoscale surface characterization of aqueous copper corrosion: Effects of immersion interval and orthophosphate concentration

Energy Technology Data Exchange (ETDEWEB)

Daniels, Stephanie L. [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); United States Environmental Protection Agency, National Risk Management Research Laboratory (NRMRL), Water Supply and Water Resource Division (WSWRD), Cincinnati, OH 45268 (United States); Sprunger, Phillip T. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Center for Advanced Microstructures and Devices, Synchrotron Radiation Facility of Louisiana State University, Baton Rouge, LA 70803 (United States); Kizilkaya, Orhan [Center for Advanced Microstructures and Devices, Synchrotron Radiation Facility of Louisiana State University, Baton Rouge, LA 70803 (United States); Lytle, Darren A. [United States Environmental Protection Agency, National Risk Management Research Laboratory (NRMRL), Water Supply and Water Resource Division (WSWRD), Cincinnati, OH 45268 (United States); Garno, Jayne C., E-mail: jgarno@lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States)

2013-11-15

Morphology changes for copper surfaces exposed to different water parameters were investigated at the nanoscale with atomic force microscopy (AFM), as influenced by changes in pH and the levels of orthophosphate ions. Synthetic water samples were designed to mimic physiological chemistries for drinking water, both with and without addition of orthophosphate over a pH range 6.5–9. Copper surfaces treated with orthophosphate as a corrosion inhibitor after 6 and 24 h were evaluated. Tapping mode AFM images revealed dosing of the water with 6 mg/L of orthophosphate was beneficial in retarding the growth of copper by-products. The chemical composition and oxidation state of the surface deposits were characterized with X-ray diffraction (XRD), near edge X-ray absorption fine structure (NEXAFS) spectroscopy and Fourier transform infrared spectroscopy (FTIR).

Solvothermal coating LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 microspheres with nanoscale Li_2TiO_3 shell for long lifespan Li-ion battery cathode materials

International Nuclear Information System (INIS)

Wu, Naiteng; Wu, Hao; Liu, Heng; Zhang, Yun

2016-01-01

LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 (NCA) microspheres covered by a nanoscale Li_2TiO_3-based shell were synthesized by a facile strategy based on a solvothermal pre-coating treatment combined with a post-sintering lithiation process. The morphology, structure and composition of the Li_2TiO_3-coated NCA samples were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning scanning electron microscope (SEM) with an energy-dispersive X-ray spectroscope (EDS), and transmission electron microscopy (TEM). Owing to the complete, uniform and nanoscale Li_2TiO_3 coating shell, the resultant surface-modified NCA microspheres used as Li-ion battery cathode materials manifest remarkably enhanced cycling performances, attaining 94% and 84% capacity retention after 200 and 400 cycles at 0.5 C, respectively, which is much better than the pristine NCA counterpart (60% retention, 200 cycles). More impressively, the surface-modified NCA also shows an intriguing storage stability. After being stored at 30 °C for 50 days, the coated NCA-based cells are subjected to be cycled both at room and elevated temperatures, in which the aged cells can still remain 84% capacity retention after 200 cycles at 25 °C and 77% capacity retention after 200 cycles at 55 °C, respectively. All these results demonstrate that the Li_2TiO_3-coated LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 microsphere is a promising cathode material for Li-ion batteries with long lifespan. - Graphical abstract: Nanoscale Li_2TiO_3-based shell encapsulated LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 (NCA) microspheres are fabricated through a solvothermal pre-coating treatment combined with post-lithiation process. The surface-coated NCA as cathode materials shows a remarkably enhanced cycling performance and storage stability for long lifespan Li-ion batteries. - Highlights: • Li_2TiO_3 is used as coating materials for layer structured LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 cathode. • Solvothermal coating

Micro- and nano-scale damage on the surface of W divertor component during exposure to high heat flux loads with He

International Nuclear Information System (INIS)

Li, C.; Greuner, H.; Zhao, S.X.; Böswirth, B.; Luo, G.N.; Zhou, X.; Jia, Y.Z.; Liu, X.; Liu, W.

2015-01-01

Micro- and nano-scale surface damage on a W divertor component sample exposed to high heat flux loads generated with He atoms has been investigated through SEM, EBSD, AFM and FIB-SEM. The component sample was supplied by the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) and AT&M company, China, and the loading experiment was performed in the GLADIS facility at IPP Garching, Germany. Two typical damage structures were observed on the surface: the first one is characterized by obvious blisters and some grooves formed from ruptured blisters, and the other one is a kind of porous structure accompanying with at least ∼25 nm surface material loss. As the grain orientation is further away from , the damage morphology gradually changes from the former structure to the latter. The possible damage mechanism is discussed. - Highlights: • Two damage structures were observed on W component surface under He beam heating. • Blistering was more obvious in near grains. • Porous structure appeared in the grains away from . • A loose layer caused by He aggregation was formed in near-surface region.

Non-oxidic nanoscale composites: single-crystalline titanium carbide nanocubes in hierarchical porous carbon monoliths.

Science.gov (United States)

Sonnenburg, Kirstin; Smarsly, Bernd M; Brezesinski, Torsten

2009-05-07

We report the preparation of nanoscale carbon-titanium carbide composites with carbide contents of up to 80 wt%. The synthesis yields single-crystalline TiC nanocubes 20-30 nm in diameter embedded in a hierarchical porous carbon matrix. These composites were generated in the form of cylindrical monoliths but can be produced in various shapes using modern sol-gel and nanocasting methods in conjunction with carbothermal reduction. The monolithic material is characterized by a combination of microscopy, diffraction and physisorption. Overall, the results presented in this work represent a concrete design template for the synthesis of non-oxidic nanoscale composites with high surface areas.

Depositing Materials on the Micro- and Nanoscale

DEFF Research Database (Denmark)

Mar, Mikkel Dysseholm; Herstrøm, Berit; Shkondin, Evgeniy

2014-01-01

on sequential introduction of precursor pulses with intermediate purging steps. The process proceeds by specific surface ligand-exchange reactions and this leads to layer-by-layer growth control. No other thin film deposition technique can approach the conformity achieved by ALD on high aspect ratio structures....... In these systems thin films of different kind are important parts of giving the system the properties needed. This can be properties like light absorbing layers, antireflection coatings or conductive layers in solar cells. It can be low stress layers in membranes, chemicals resistant layers in chemical sensors......, layers with specific optical properties in optical sensors, piezoelectric thin films or insulating layers in many other applications. These different materials and properties impose a demand for different kind of deposition techniques. At DTU Danchip we have a large variety of these deposition techniques...

Structure and tensile properties of Fe-Cr model alloy strengthened by nano-scale NbC particles derived from controlled crystallization of Nb-rich clusters

Energy Technology Data Exchange (ETDEWEB)

Dai, Lei [College of Materials and Chemical Engineering, Three Gorges University, Yichang 443002 (China); Guo, Qianying [State Key Lab of Hydraulic Engineering Simulation and Safety, School of Material Science and Engineering, Tianjin University, Tianjin 300354 (China); Liu, Yongchang, E-mail: licmtju@163.com [State Key Lab of Hydraulic Engineering Simulation and Safety, School of Material Science and Engineering, Tianjin University, Tianjin 300354 (China); Yu, Liming; Li, Huijun [State Key Lab of Hydraulic Engineering Simulation and Safety, School of Material Science and Engineering, Tianjin University, Tianjin 300354 (China)

2016-09-30

This article describes the microstructural evolution and tensile properties of Fe-Cr model alloy strengthened by nano-scale NbC particles. According to the results obtained from X-ray diffraction and transmission electron microscope with Energy Dispersive Spectrometer, the bcc ultrafine grains and the disordered phase of Nb-rich nano-clusters were observed in the milled powders. The hot pressing (HP) resulted in a nearly equiaxed ferritic grains and dispersed nano-scale NbC (~8 nm) particles. The microstructure studies reveal that the formation of NbC nanoparticles is composed of nucleation and growth of the Nb-rich nano-clusters involving diffusion of their component. At room temperature the material exhibits an ultimate tensile strength of 700 MPa, yield strength of 650 MPa, and total elongation of 11.7 pct. The fracture surface studies reveal that a typical ductile fracture mode has occurred during tensile test.

Surface modification of food contact materials for processing and packaging applications

Science.gov (United States)

Barish, Jeffrey A.

This body of work investigates various techniques for the surface modification of food contact materials for use in food packaging and processing applications. Nanoscale changes to the surface of polymeric food packaging materials enables changes in adhesion, wettability, printability, chemical functionality, and bioactivity, while maintaining desirable bulk properties. Polymer surface modification is used in applications such as antimicrobial or non-fouling materials, biosensors, and active packaging. Non-migratory active packagings, in which bioactive components are tethered to the package, offer the potential to reduce the need for additives in food products while maintaining safety and quality. A challenge in developing non-migratory active packaging materials is the loss of biomolecular activity that can occur when biomolecules are immobilized. Polyethylene glycol (PEG), a biocompatible polymer, is grafted from the surface of ozone treated low-density polyethylene (LDPE) resulting in a surface functionalized polyethylene to which a range of amine-terminated bioactive molecules can be immobilized. The grafting of PEG onto the surface of polymer packaging films is accomplished by free radical graft polymerization, and to covalently link an amine-terminated molecule to the PEG tether, demonstrating that amine-terminated bioactive compounds (such as peptides, enzymes, and some antimicrobials) can be immobilized onto PEG-grafted LDPE in the development of non-migratory active packaging. Fouling on food contact surfaces during food processing has a significant impact on operating efficiency and can promote biofilm development. Processing raw milk on plate heat exchangers results in significant fouling of proteins as well as minerals, and is exacerbated by the wall heating effect. An electroless nickel coating is co-deposited with polytetrafluoroethylene onto stainless steel to test its ability to resist fouling on a pilot plant scale plate heat exchanger. Further

Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

Energy Technology Data Exchange (ETDEWEB)

Borghi, F.; Lenardi, C.; Podestà, A.; Milani, P., E-mail: pmilani@mi.infn.it [CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Sogne, E. [CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); European School of Molecular Medicine (SEMM), IFOM-IEO, Milano (Italy); Merlini, M. [Dipartimento di Scienze della Terra “Ardito Desio”, Università degli Studi di Milano, via Mangiagalli 32, 20133 Milano (Italy); Ducati, C. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

2016-08-07

Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments.

Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

International Nuclear Information System (INIS)

Borghi, F.; Lenardi, C.; Podestà, A.; Milani, P.; Sogne, E.; Merlini, M.; Ducati, C.

2016-01-01

Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments.

Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

KAUST Repository

Borghi, F.

2016-08-05

Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments. Published by AIP Publishing.

Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

KAUST Repository

Borghi, F.; Sogne, Elisa; Lenardi, C.; Podestà , A.; Merlini, M.; Ducati, C.; Milani, P.

2016-01-01

Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments. Published by AIP Publishing.

Effect of UV/ozone treatment on the nanoscale surface properties of gold implanted polyethylene

Energy Technology Data Exchange (ETDEWEB)

Kisić, Danilo; Nenadović, Miloš [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade (Serbia); Štrbac, Svetlana [ICTM Institute of Electrochemistry, University of Belgrade, Njegoseva 12, 11001 Belgrade (Serbia); Adnadjević, Borivoj [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Rakočević, Zlatko, E-mail: zlatkora@vinca.rs [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade (Serbia)

2014-07-01

The effect of ultraviolet (UV) ozone treatment on the surface properties of gold implanted high density polyethylene (HDPE) was investigated at a nanoscale using Atomic Force Microscopy (AFM). HDPE samples were modified by the implantation of gold ions at a dose of 5 × 10{sup 15} ions/cm{sup 2}, using energies of 50, 100, 150, and 200 keV, and subsequently treated with UV/ozone. AFM surface topography images revealed that after UV/ozone treatment, the surface roughness of all Au/HDPE samples increased, while Power Spectral Density function increased only for samples implanted using higher energies, with a maximum for 150 keV. The chemical surface composition was homogenous in all cases, which was evidenced by the appearance of single peaks in the histograms obtained from the phase AFM images. For UV/ozone treated samples, the shift of the peaks positions in the histograms to the higher values of the phase lag with respect to untreated ones indicated the decrease of surface hardness. Besides, a significant change of fractal dimension of surface grains is observed after UV/ozone treatment.

Interface chemistry of nanostructured materials: ion adsorption on mesoporous alumina.

Science.gov (United States)

Wang, Yifeng; Bryan, Charles; Xu, Huifang; Pohl, Phil; Yang, Yi; Brinker, C Jeffrey

2002-10-01

This paper presents a part of our work on understanding the effect of nanoscale pore space confinement on ion sorption by mesoporous materials. Acid-base titration experiments were performed on both mesoporous alumina and alumina particles under various ionic strengths. The point of zero charge (PZC) for mesoporous alumina was measured to be approximately 9.1, similar to that for nonmesoporous alumina materials, indicating that nanoscale pore space confinement does not have a significant effect on the PZC of pore surfaces. However, for a given pH deviation from the PZC, (pH-PZC), the surface charge per mass on mesoporous alumina was as much as 45 times higher than that on alumina particles. This difference cannot be fully explained by the surface area difference between the two materials. Our titration data have demonstrated that nanoscale confinement has a significant effect, most likely via the overlap of the electric double layer (EDL), on ion sorption onto mesopore surfaces. This effect cannot be adequately modeled by existing surface complexation models, which were developed mostly for an unconfined solid-water interface. Our titration data have also indicated that the rate of ion uptake by mesoporous alumina is relatively slow, probably due to diffusion into mesopores, and complete equilibration for sorption could take 4-5 min. A molecular simulation using a density functional theory was performed to calculate ion adsorption coefficients as a function of pore size. The calculation has shown that as pore size is reduced to nanoscales (<10 nm), the adsorption coefficients of ions can vary by more than two orders of magnitude relative to those for unconfined interfaces. The prediction is supported by our experimental data on Zn sorption onto mesoporous alumina. Owing to their unique surface chemistry, mesoporous materials can potentially be used as effective ion adsorbents for separation processes and environmental cleanup.

Cold atmospheric plasma (CAP) surface nanomodified 3D printed polylactic acid (PLA) scaffolds for bone regeneration.

Science.gov (United States)

Wang, Mian; Favi, Pelagie; Cheng, Xiaoqian; Golshan, Negar H; Ziemer, Katherine S; Keidar, Michael; Webster, Thomas J

2016-12-01

Three-dimensional (3D) printing is a new fabrication method for tissue engineering which can precisely control scaffold architecture at the micron-scale. However, scaffolds not only need 3D biocompatible structures that mimic the micron structure of natural tissues, they also require mimicking of the nano-scale extracellular matrix properties of the tissue they intend to replace. In order to achieve this, the objective of the present in vitro study was to use cold atmospheric plasma (CAP) as a quick and inexpensive way to modify the nano-scale roughness and chemical composition of a 3D printed scaffold surface. Water contact angles of a normal 3D printed poly-lactic-acid (PLA) scaffold dramatically dropped after CAP treatment from 70±2° to 24±2°. In addition, the nano-scale surface roughness (Rq) of the untreated 3D PLA scaffolds drastically increased (up to 250%) after 1, 3, and 5min of CAP treatment from 1.20nm to 10.50nm, 22.90nm, and 27.60nm, respectively. X-ray photoelectron spectroscopy (XPS) analysis showed that the ratio of oxygen to carbon significantly increased after CAP treatment, which indicated that the CAP treatment of PLA not only changed nano-scale roughness but also chemistry. Both changes in hydrophilicity and nano-scale roughness demonstrated a very efficient plasma treatment, which in turn significantly promoted both osteoblast (bone forming cells) and mesenchymal stem cell attachment and proliferation. These promising results suggest that CAP surface modification may have potential applications for enhancing 3D printed PLA bone tissue engineering materials (and all 3D printed materials) in a quick and an inexpensive manner and, thus, should be further studied. Three-dimensional (3D) printing is a new fabrication method for tissue engineering which can precisely control scaffold architecture at the micron-scale. Although their success is related to their ability to exactly mimic the structure of natural tissues and control mechanical

In vivo micronucleus studies with 6 titanium dioxide materials (3 pigment-grade & 3 nanoscale) in orally-exposed rats.

Science.gov (United States)

Donner, E M; Myhre, A; Brown, S C; Boatman, R; Warheit, D B

2016-02-01

Six pigment-grade (pg) or ultrafine (uf)/nanoscale (anatase and/or rutile) titanium dioxide (TiO2) particulates were evaluated for in vivo genotoxicity (OECD 474 Guidelines) in male and female rats by two different laboratories. All test materials were robustly characterized. The BET surface areas of the pg and uf samples ranged from 7 to 17 m(2)/g and 50 to 82 m(2)/g respectively. The materials were assessed for induction of micronuclei and toxicity in bone marrow by analyzing peripheral blood reticulocytes (RETs) by flow cytometry. Single oral gavage doses of 500, 1000 or 2000 mg/kg body weight (bw) of each material were implemented with concurrent negative (water) and positive controls (cyclophosphamide). Approximately 48 and 72 h after exposure, blood samples were collected and 20,000 RETs per animal were analyzed. For each of the six tests, there were no biologically or toxicologically relevant increases in the micronucleated RET frequency in any TiO2 exposed group at either time point at any dose level. In addition, there were a lack of biologically relevant decreases in %RETs among total erythrocytes. All six TiO2 test substances were negative for in vivo genotoxicity effects; however, it is noted that the exposure to target tissues was likely negligible. One pigment grade and one ultrafine material each were evaluated for potential systemic exposure/uptake from the gastrointestinal tract by analysis of TiO2 into blood and liver. No significant increases in TiO2 over controls were measured in blood (48 or 72 h) or liver (72 h) following exposures to 2000 mg/kg bw TiO2. These data indicate that there was no absorption of the test material from the gastrointestinal tract into the blood circulation and the lack of genotoxic effects is therefore attributed to a lack of exposure due to the inability of the test material to migrate from the gastrointestinal tract into the blood and then into target tissues. Copyright © 2015 Elsevier Inc. All rights

Exchange-coupled nanoscale SmCo/NdFeB hybrid magnets

Energy Technology Data Exchange (ETDEWEB)

Wang Dapeng; Poudyal, Narayan; Rong, Chuanbing [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Zhang Ying [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Materials Science and Engineering, Ames Laboratory, USDOE, Iowa State University, Ames, IA 50011 (United States); Kramer, M.J. [Materials Science and Engineering, Ames Laboratory, USDOE, Iowa State University, Ames, IA 50011 (United States); Liu, J. Ping, E-mail: pliu@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

2012-09-15

Nanoscale hybrid magnets containing SmCo{sub 5} and Nd{sub 2}Fe{sub 14}B hard magnetic phases have been produced via a novel 'in-one-pot' processing route. The grain size of the processed bulk composite materials is controlled below 20 nm. The refinement of the nanoscale morphology leads to effective inter-phase exchange coupling that results in single-phase like magnetic properties. Energy product of 14 MGOe was obtained in the isotropic nanocomposite magnets at room temperature. At elevated temperatures, the hybrid magnets have greatly improved thermal stability compared to the Nd{sub 2}Fe{sub 14}B single-phase counterpart and have substantially increased magnetization and energy products compared to the single-phase SmCo{sub 5} counterpart. - Highlights: Black-Right-Pointing-Pointer We realize interphase exchange coupling in nanoscale SmCo{sub 5}/Nd{sub 2}Fe{sub 14}B magnets. Black-Right-Pointing-Pointer We observe homogenously distributed two-phase grains with size smaller than 20 nm. Black-Right-Pointing-Pointer We observe a common Curie temperature in the hybrid magnet. Black-Right-Pointing-Pointer High-temperature magnetic properties of the hybrid magnets greatly improved. Black-Right-Pointing-Pointer Plastic deformation of composite materials leads to self-nanoscaling of grains.

Molecular dynamics simulation of nanoscale surface diffusion of heterogeneous adatoms clusters

International Nuclear Information System (INIS)

Imran, Muhammad; Hussain, Fayyaz; Ullah, Hafeez; Ahmad, Ejaz; Rashid, Muhammad; Ismail, Muhammad; Cai, Yongqing; Javid, M Arshad; Ahmad, S A

2016-01-01

Molecular dynamics simulation employing the embedded atom method potential is utilized to investigate nanoscale surface diffusion mechanisms of binary heterogeneous adatoms clusters at 300 K, 500 K, and 700 K. Surface diffusion of heterogeneous adatoms clusters can be vital for the binary island growth on the surface and can be useful for the formation of alloy-based thin film surface through atomic exchange process. The results of the diffusion process show that at 300 K, the diffusion of small adatoms clusters shows hopping, sliding, and shear motion; whereas for large adatoms clusters (hexamer and above), the diffusion is negligible. At 500 K, small adatoms clusters, i.e., dimer, show almost all possible diffusion mechanisms including the atomic exchange process; however no such exchange is observed for adatoms clusters greater than dimer. At 700 K, the exchange mechanism dominates for all types of clusters, where Zr adatoms show maximum tendency and Ag adatoms show minimum or no tendency toward the exchange process. Separation and recombination of one or more adatoms are also observed at 500 K and 700 K. The Ag adatoms also occupy pop-up positions over the adatoms clusters for short intervals. At 700 K, the vacancies are also generated in the vicinity of the adatoms cluster, vacancy formation, filling, and shifting can be observed from the results. (paper)

Grain size and nanoscale effects on the nonlinear pull-in instability and vibrations of electrostatic actuators made of nanocrystalline material

Science.gov (United States)

Gholami, R.; Ansari, R.

2018-01-01

Presented herein is the study of grain size, grain surface energy and small scale effects on the nonlinear pull-in instability and free vibration of electrostatic nanoscale actuators made of nanocrystalline silicon (Nc-Si). A Mori-Tanaka micromechanical model is utilized to calculate the effective material properties of Nc-Si considering material structure inhomogeneity, grain size and grain surface energy. The small-scale effect is also taken into account using Mindlin’s strain gradient theory. Governing equations are derived in the discretized weak form using the variational differential quadrature method based on the third-order shear defamation beam theory in conjunction with the von Kármán hypothesis. The electrostatic actuation is modeled considering the fringing field effects based upon the parallel plate approximation. Moreover, the Casimir force effect is considered. The pseudo arc-length continuation technique is used to obtain the applied voltage-deflection curve of Nc-Si actuators. Then, a time-dependent small disturbance around the deflected configuration is assumed to solve the free vibration problem. By performing a numerical study, the influences of various factors such as length scale parameter, volume fraction of the inclusion phase, density ratio, average inclusion radius and Casimir force on the pull-in instability and free vibration of Nc-Si actuators are investigated.

Molecular insight into nanoscale water films dewetting on modified silica surfaces.

Science.gov (United States)

Zhang, Jun; Li, Wen; Yan, Youguo; Wang, Yefei; Liu, Bing; Shen, Yue; Chen, Haixiang; Liu, Liang

2015-01-07

In this work, molecular dynamics simulations are adopted to investigate the microscopic dewetting mechanism of nanoscale water films on methylated silica surfaces. The simulation results show that the dewetting process is divided into two stages: the appearance of dry patches and the quick contraction of the water film. First, the appearance of dry patches is due to the fluctuation in the film thickness originating from capillary wave instability. Second, for the fast contraction of water film, the unsaturated electrostatic and hydrogen bond interactions among water molecules are the driving forces, which induce the quick contraction of the water film. Finally, the effect of film thickness on water films dewetting is studied. Research results suggest that upon increasing the water film thickness from 6 to 8 Å, the final dewetting patterns experience separate droplets and striation-shaped structures, respectively. But upon further increasing the water film thickness, the water film is stable and there are no dry patches. The microscopic dewetting behaviors of water films on methylated silica surfaces discussed here are helpful in understanding many phenomena in scientific and industrial processes better.

Nanoscale Structural/Chemical Characterization of Manganese Oxide Surface Layers and Nanoparticles, and the Associated Implications for Drinking Water

Science.gov (United States)

Michel Eduardo Vargas Vallejo

Water treatment facilities commonly reduce soluble contaminants, such as soluble manganese (Mn2+), in water by oxidation and subsequent filtration. Previous studies have shown that conventional porous filter system removes Mn2+ from drinking water by developing Mn-oxides (MnO x(s)) bearing coating layers on the surface of filter media. Multiple models have been developed to explain this Mn2+ removal process and the formation mechanism of MnOx(s) coatings. Both, experimental and theoretical studies to date have been largely focused on the micrometer to millimeter scale range; whereas, coating layers are composed of nanoscale particles and films. Hence, understanding the nanoscale particle and film formation mechanisms is essential to comprehend the complexity of soluble contaminant removal processes. The primary objective of this study was to understand the initial MnOx(s) coating formation mechanisms and evaluate the influence of filter media characteristics on these processes. We pursued this objective by characterizing at the micro and nanoscale MnO x(s) coatings developed on different filter media by bench-scale column tests with simulating inorganic aqueous chemistry of a typical coagulation fresh water treatment plant, where free chlorine is present across filter bed. Analytical SEM and TEM, powder and synchrotron-based XRD, XPS, and ICPMS were used for characterization of coatings, filter media and water solution elemental chemistry. A secondary objective was to model how surface coating formation occurred and its correlation with experimentally observed physical characteristics. This modeling exercise indicates that surface roughness and morphology of filtering media are the major contributing factors in surface coating formation process. Contrary to previous models that assumed a uniform distribution and growth of surface coating, the experimental results showed that greater amounts of coating were developed in rougher areas. At the very early stage of

Nanoscale organization of {beta}{sub 2}-adrenergic receptor-Venus fusion protein domains on the surface of mammalian cells

Energy Technology Data Exchange (ETDEWEB)

Vobornik, Dusan; Rouleau, Yanouchka; Haley, Jennifer [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Bani-Yaghoub, Mahmud [Institute for Biological Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Taylor, Rod [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Johnston, Linda J., E-mail: Linda.Johnston@nrc-cnrc.gc.ca [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Pezacki, John Paul, E-mail: John.Pezacki@nrc-cnrc.gc.ca [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada)

2009-04-24

Adrenergic receptors are a key component of nanoscale multiprotein complexes that are responsible for controlling the beat rate in a mammalian heart. We demonstrate the ability of near-field scanning optical microscopy (NSOM) to visualize {beta}{sub 2}-adrenergic receptors ({beta}{sub 2}AR) fused to the GFP analogue Venus at the nanoscale on HEK293 cells. The expression of the {beta}{sub 2}AR-Venus fusion protein was tightly controlled using a tetracycline-induced promoter. Both the size and density of the observed nanoscale domains are dependent on the level of induction and thus the level of protein expression. At concentrations between 100 and 700 ng/ml of inducer doxycycline, the size of domains containing the {beta}{sub 2}AR-Venus fusion protein appears to remain roughly constant, but the number of domains per cell increase. At 700 ng/ml doxycycline the functional receptors are organized into domains with an average diameter of 150 nm with a density similar to that observed for the native protein on primary murine cells. By contrast, larger micron-sized domains of {beta}{sub 2}AR are observed in the membrane of the HEK293 cells that stably overexpress {beta}{sub 2}AR-GFP and {beta}{sub 2}AR-eYFP. We conclude that precise chemical control of gene expression is highly advantageous for the use {beta}{sub 2}AR-Venus fusion proteins as models for {beta}{sub 2}AR function. These observations are critical for designing future cell models and assays based on {beta}{sub 2}AR, since the receptor biology is consistent with a relatively low density of nanoscale receptor domains.

Nanoscale shape-memory alloys for ultrahigh mechanical damping.

Science.gov (United States)

San Juan, Jose; Nó, Maria L; Schuh, Christopher A

2009-07-01

Shape memory alloys undergo reversible transformations between two distinct phases in response to changes in temperature or applied stress. The creation and motion of the internal interfaces between these phases during such transformations dissipates energy, making these alloys effective mechanical damping materials. Although it has been shown that reversible phase transformations can occur in nanoscale volumes, it is not known whether these transformations have a sample size dependence. Here, we demonstrate that the two phases responsible for shape memory in Cu-Al-Ni alloys are more stable in nanoscale pillars than they are in the bulk. As a result, the pillars show a damping figure of merit that is substantially higher than any previously reported value for a bulk material, making them attractive for damping applications in nanoscale and microscale devices.

Nanoscale photoelectron ionisation detector based on lanthanum hexaboride

International Nuclear Information System (INIS)

Zimmer, C.M.; Kunze, U.; Schubert, J.; Hamann, S.; Doll, T.

2011-01-01

A nanoscale ioniser is presented exceeding the limitation of conventional photoionisation detectors. It employs accelerated photoelectrons that allow obtaining molecule specificity by the tuning of ionisation energies. The material lanthanum hexaboride (LaB 6 ) is used as air stable photo cathode. Thin films of that material deposited by pulsed laser deposition (PLD) show quantum efficiency (QE) in the range of 10 -5 which is comparable to laser photo stimulation results. A careful treatment of the material yields reasonable low work functions even after surface reoxidation which opens up the possibility of using ultraviolet light emitting diodes (UV LEDs) in replacement of discharge lamps. Schematic diagram of a photoelectron ionisation detector (PeID) operating by an electron emitter based on the photoelectric effect of lanthanum hexaboride. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

In-situ X-ray absorption spectroscopy analysis of capacity fade in nanoscale-LiCoO2

International Nuclear Information System (INIS)

Patridge, Christopher J.; Love, Corey T.; Swider-Lyons, Karen E.; Twigg, Mark E.; Ramaker, David E.

2013-01-01

The local structure of nanoscale (∼10–40 nm) LiCoO 2 is monitored during electrochemical cycling utilizing in-situ X-ray absorption spectroscopy (XAS). The high surface area of the LiCoO 2 nanoparticles not only enhances capacity fade, but also provides a large signal from the particle surface relative to the bulk. Changes in the nanoscale LiCoO 2 metal-oxide bond lengths, structural disorder, and chemical state are tracked during cycling by adapting the delta mu (Δμ) technique in complement with comprehensive extended X-ray absorption fine structure (EXAFS) modeling. For the first time, we use a Δμ EXAFS method, and by comparison of the difference EXAFS spectra, extrapolate significant coordination changes and reduction of cobalt species with cycling. This combined approach suggests Li–Co site exchange at the surface of the nanoscale LiCoO 2 as a likely factor in the capacity fade and irreversible losses in practical, microscale LiCoO 2 . - Graphical abstract: Electrochemical cycling of Li-ion batteries has strong impact on the structure and integrity of the cathode active material particularly near the surface/electrolyte interface. In developing a new method, we have used in-situ X-ray absorption spectroscopy during electrochemical cycling of nanoscale LiCoO 2 to track changes during charge and discharge and between subsequent cycles. Using difference spectra, several small changes in Co-O bond length, Co-O and Co-Co coordination, and site exchange between Co and Li sites can be tracked. These methods show promise as a new technique to better understand processes which lead to capacity fade and loss in Li-ion batteries. - Highlights: • A new method is developed to understand capacity fade in Li-ion battery cathodes. • Structural changes are tracked during Li intercalation/deintercalation of LiCoO 2 . • Surface structural changes are emphasized using nanoscale-LiCoO 2 and difference spectra. • Full multiple scattering calculations are used to

Probing the nanoscale interaction forces and elastic properties of organic and inorganic materials using force-distance (F-D) spectroscopy

Science.gov (United States)

Vincent, Abhilash

Due to their therapeutic applications such as radical scavenging, MRI contrast imaging, Photoluminescence imaging, drug delivery, etc., nanoparticles (NPs) have a significant importance in bio-nanotechnology. The reason that prevents the utilizing NPs for drug delivery in medical field is mostly due to their biocompatibility issues (incompatibility can lead to toxicity and cell death). Changes in the surface conditions of NPs often lead to NP cytotoxicity. Investigating the role of NP surface properties (surface charges and surface chemistry) on their interactions with biomolecules (Cells, protein and DNA) could enhance the current understanding of NP cytotoxicity. Hence, it is highly beneficial to the nanotechnology community to bring more attention towards the enhancement of surface properties of NPs to make them more biocompatible and less toxic to biological systems. Surface functionalization of NPs using specific ligand biomolecules have shown to enhance the protein adsorption and cellular uptake through more favorable interaction pathways. Cerium oxide NPs (CNPs also known as nanoceria) are potential antioxidants in cell culture models and understanding the nature of interaction between cerium oxide NPs and biological proteins and cells are important due to their therapeutic application (especially in site specific drug delivery systems). The surface charges and surface chemistry of CNPs play a major role in protein adsorption and cellular uptake. Hence, by tuning the surface charges and by selecting proper functional molecules on the surface, CNPs exhibiting strong adhesion to biological materials can be prepared. By probing the nanoscale interaction forces acting between CNPs and protein molecules using Atomic Force Microscopy (AFM) based force-distance (F-D) spectroscopy, the mechanism of CNP-protein adsorption and CNP cellular uptake can be understood more quantitatively. The work presented in this dissertation is based on the application of AFM in

Nanoscale MOS devices: device parameter fluctuations and low-frequency noise (Invited Paper)

Science.gov (United States)

Wong, Hei; Iwai, Hiroshi; Liou, J. J.

2005-05-01

It is well-known in conventional MOS transistors that the low-frequency noise or flicker noise is mainly contributed by the trapping-detrapping events in the gate oxide and the mobility fluctuation in the surface channel. In nanoscale MOS transistors, the number of trapping-detrapping events becomes less important because of the large direct tunneling current through the ultrathin gate dielectric which reduces the probability of trapping-detrapping and the level of leakage current fluctuation. Other noise sources become more significant in nanoscale devices. The source and drain resistance noises have greater impact on the drain current noise. Significant contribution of the parasitic bipolar transistor noise in ultra-short channel and channel mobility fluctuation to the channel noise are observed. The channel mobility fluctuation in nanoscale devices could be due to the local composition fluctuation of the gate dielectric material which gives rise to the permittivity fluctuation along the channel and results in gigantic channel potential fluctuation. On the other hand, the statistical variations of the device parameters across the wafer would cause the noise measurements less accurate which will be a challenge for the applicability of analytical flicker noise model as a process or device evaluation tool for nanoscale devices. Some measures for circumventing these difficulties are proposed.

Acute toxicity of quantum dots on late pregnancy mice: Effects of nanoscale size and surface coating

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wanyi [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); The Second Affiliated Hospital of Nanchang University, Nanchang 330000 (China); Yang, Lin; Kuang, Huijuan; Yang, Pengfei [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Aguilar, Zoraida P.; Wang, Andrew [Ocean NanoTech, LLC, Springdale, AR72764 (United States); Fu, Fen, E-mail: fu_fen@163.com [The Second Affiliated Hospital of Nanchang University, Nanchang 330000 (China); Xu, Hengyi, E-mail: kidyxu@163.com [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China)

2016-11-15

Graphical abstract: In spite of the immense benefits from quantum dots (QDs), there is scanty information regarding their toxicity mechanisms against late pregnancy. - Highlights: • QDs and CdCl{sub 2} were effectively blocked by the placental barrier. • CdSe QDs more effectively altered the expression levels of susceptive genes. • Nanoscale size of QDs is more important than free Cd in inducing toxicity. • Outer surface shell coating of QDs played a protective role. - Abstract: In this study, the effects of cadmium containing QDs (such as CdSe/ZnS and CdSe QDs) and bulk CdCl{sub 2} in pregnant mice, their fetuses, and the pregnancy outcomes were investigated. It was shown that although the QDs and bulk CdCl{sub 2} were effectively blocked by the placental barrier, the damage on the placenta caused by CdSe QDs still led to fetus malformation, while the mice in CdSe/ZnS QDs treatment group exhibited slightly hampered growth but showed no significant abnormalities. Moreover, the Cd contents in the placenta and the uterus of CdSe QDs and CdSe/ZnS QDs treatment groups showed significantly higher than the CdCl{sub 2} treated group which indicated that the nanoscale size of the QDs allowed relative ease of entry into the gestation tissues. In addition, the CdSe QDs more effectively altered the expression levels of susceptive genes related to cell apoptosis, dysplasia, metal transport, cryptorrhea, and oxidative stress, etc. These findings suggested that the nanoscale size of the QDs were probably more important than the free Cd in inducing toxicity. Furthermore, the results indicated that the outer surface shell coating played a protective role in the adverse effects of QDs on late pregnancy mice.

Surface Characteristics and Biofilm Development on Selected Dental Ceramic Materials

Directory of Open Access Journals (Sweden)

Kyoung H. Kim

2017-01-01

Full Text Available Background. Intraoral adjustment and polishing of dental ceramics often affect their surface characteristics, promoting increased roughness and consequent biofilm growth. This study correlated surface roughness to biofilm development with four commercially available ceramic materials. Methods. Four ceramic materials (Vita Enamic®, Lava™ Ultimate, Vitablocs Mark II, and Wieland Reflex® were prepared as per manufacturer instructions. Seventeen specimens of each material were adjusted and polished to simulate clinical intraoral procedures and another seventeen remained unaltered. Specimens were analysed by SEM imaging, confocal microscopy, and crystal violet assay. Results. SEM images showed more irregular surface topography in adjusted specimens than their respective controls. Surface roughness (Ra values were greater in all materials following adjustments. All adjusted materials with the exception of Vitablocs Mark II promoted significantly greater biofilm growth relative to controls. Conclusion. Simulated intraoral polishing methods resulted in greater surface roughness and increased biofilm accumulation.

Advanced energy materials (Preface)

Science.gov (United States)

Titus, Elby; Ventura, João; Araújo, João Pedro; Campos Gil, João

2017-12-01

Advances in material science make it possible to fabricate the building blocks of an entirely new generation of hierarchical energy materials. Recent developments were focused on functionality and areas connecting macroscopic to atomic and nanoscale properties, where surfaces, defects, interfaces and metastable state of the materials played crucial roles. The idea is to combine both, the top-down and bottom-up approach as well as shape future materials with a blend of both the paradigms.

Nanoscale indent formation in shape memory polymers using a heated probe tip

Energy Technology Data Exchange (ETDEWEB)

Yang, F [Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801 (United States); Wornyo, E [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Gall, K [Department of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); King, W P [Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801 (United States)

2007-07-18

This paper presents experimental investigation of nanoscale indentation formation in shape memory polymers. The polymers were synthesized by photopolymerizing a tert-butyl acrylate (tBA) monomer with a poly(ethylene glycol dimethacrylate) (PEGDMA) crosslinker. The concentration and the molecular weight of the crosslinker were varied to produce five polymers with tailored properties. Nanoscale indentations were formed on the polymer surfaces by using a heated atomic force microscope (AFM) cantilever at various temperatures near or above the glass transition (between 84 and 215 deg. C) and a range of heating durations from 100 {mu}s to 8 ms. The images of the indents were obtained with the same probe tip at room temperature. The contact pressure, a measure of transient hardness, was derived from the indentation height data as a function of time and temperature for different polymers. With increasing crosslinker molecular weight and decreasing crosslinker concentration, the contact pressures decreased at a fixed maximum load due to increased crosslink spacing in the polymer system. The results provide insight into the nanoscale response of these novel materials.

A review of nanostructured surfaces and materials for dental implants: surface coating, patterning and functionalization for improved performance.

Science.gov (United States)

Rasouli, Rahimeh; Barhoum, Ahmed; Uludag, Hasan

2018-05-10

The emerging field of nanostructured implants has enormous scope in the areas of medical science and dental implants. Surface nanofeatures provide significant potential solutions to medical problems by the introduction of better biomaterials, improved implant design, and surface engineering techniques such as coating, patterning, functionalization and molecular grafting at the nanoscale. This review is of an interdisciplinary nature, addressing the history and development of dental implants and the emerging area of nanotechnology in dental implants. After a brief introduction to nanotechnology in dental implants and the main classes of dental implants, an overview of different types of nanomaterials (i.e. metals, metal oxides, ceramics, polymers and hydrides) used in dental implant together with their unique properties, the influence of elemental compositions, and surface morphologies and possible applications are presented from a chemical point of view. In the core of this review, the dental implant materials, physical and chemical fabrication techniques and the role of nanotechnology in achieving ideal dental implants have been discussed. Finally, the critical parameters in dental implant design and available data on the current dental implant surfaces that use nanotopography in clinical dentistry have been discussed.

Fabrication of all diamond scanning probes for nanoscale magnetometry

OpenAIRE

Appel Patrick; Neu Elke; Ganzhorn Marc; Barfuss Arne; Batzer Marietta; Gratz Micha; Tschoepe Andreas; Maletinsky Patrick

2016-01-01

The electronic spin of the nitrogen vacancy (NV) center in diamond forms an atomically sized, highly sensitive sensor for magnetic fields. To harness the full potential of individual NV centers for sensing with high sensitivity and nanoscale spatial resolution, NV centers have to be incorporated into scanning probe structures enabling controlled scanning in close proximity to the sample surface. Here, we present an optimized procedure to fabricate single-crystal, all-diamond scanning probes s...

Enhancement of critical current density of YBa2Cu3O7-δ thin films by nanoscale CeO2 pretreatment of substrate surfaces

International Nuclear Information System (INIS)

Cui, X.M.; Liu, G.Q.; Wang, J.; Huang, Z.C.; Zhao, Y.T.; Tao, B.W.; Li, Y.R.

2007-01-01

YBa 2 Cu 3 O 7-δ (YBCO) films were prepared on single-crystal SrTiO 3 substrates with metal-organic deposition using trifluoroacetates (TFA-MOD). Positive results have been acquired in controlled study to investigate the effects of substrate surface modification on the growth-induced flux-pinning nanostructures in YBCO films. Nanoscale CeO 2 particles were applied to single-crystal SrTiO 3 substrate surfaces using pulsed laser deposition before YBCO precursors coating. Superconducting properties of the YBCO films grown on the controlled CeO 2 -modified substrates have shown substantial improvement in the critical current densities (J c ) at 77 K over those grown on untreated substrates in almost all the field (78% increment at 1 T, 77 K). We think the reason is that the CeO 2 nanoparticles act as pinning centers

Scanning nanoscale multiprobes for conductivity measurements

DEFF Research Database (Denmark)

Bøggild, Peter; Hansen, Torben Mikael; Kuhn, Oliver

2000-01-01

We report fabrication and measurements with two- and four-point probes with nanoscale dimensions, for high spatial resolution conductivity measurements on surfaces and thin films. By combination of conventional microfabrication and additive three-dimensional nanolithography, we have obtained...... electrode spacings down to 200 nm. At the tips of four silicon oxide microcantilevers, narrow carbon tips are grown in converging directions and subsequently coated with a conducting layer. The probe is placed in contact with a conducting surface, whereby the electrode resistance can be determined....... The nanoelectrodes withstand considerable contact force before breaking. The probe offers a unique possibility to position the voltage sensors, as well as the source and drain electrodes in areas of nanoscale dimensions. ©2000 American Institute of Physics....

Development of Self-Assembled Nanoscale Templates via Microphase Separation Induced by Polymer Brushes

Science.gov (United States)

Chu, Elza

Phase separation in soft matter has been the crucial element in generating hybrid materials, such as polymer blends and mixed polymer brushes. This dissertation discusses two methods of developing self-assembled nanoscale templates via microphase separation induced by polymer brush synthesis. This work introduces a novel soft substrate approach with renewable grafting sites where polyacrylamide is "grafted through" chitosan soft substrates. The mechanism of grafting leads to ordered arrays of filament-like nanostructures spanning the chitosan-air interface. Additionally, the chemical composition of the filaments allows for post-chemical modification to change the physical properties of the filaments, and subsequently tailor surfaces for specific application. Unlike traditional materials, multi-functional or "smart" materials, such as binary polymer brushes (BPB) are capable of spontaneously changing the spatial distribution of functional groups and morphology at the surface upon external stimuli. Although promising in principle, the limited range of available complementary polymers with common non-selective solvents confines the diversity of usable materials and restricts any further advancement in the field. This dissertation also covers the fabrication and characterization of responsive nanoscale polystyrene templates or "mosaic" brushes that are capable of changing interfacial composition upon exposure to varying solvent qualities. Using a "mosaic" brush template is a unique approach that allows the fabrication of strongly immiscible polymer BPB without the need for a common solvent. The synthesis of such BPB is exemplified by two strongly immiscible polymers, i.e. polystyrene (polar) and polyacrylamide (non-polar), where polyacrylamide brush is "graft through" a Si-substrate modified with the polystyrene collapsed "mosaic" brush. The surface exhibits solvent-triggered responses, as well as application potential for anti-biofouling.

Study of nanoscale structural biology using advanced particle beam microscopy

Science.gov (United States)

Boseman, Adam J.

This work investigates developmental and structural biology at the nanoscale using current advancements in particle beam microscopy. Typically the examination of micro- and nanoscale features is performed using scanning electron microscopy (SEM), but in order to decrease surface charging, and increase resolution, an obscuring conductive layer is applied to the sample surface. As magnification increases, this layer begins to limit the ability to identify nanoscale surface structures. A new technology, Helium Ion Microscopy (HIM), is used to examine uncoated surface structures on the cuticle of wild type and mutant fruit flies. Corneal nanostructures observed with HIM are further investigated by FIB/SEM to provide detailed three dimensional information about internal events occurring during early structural development. These techniques are also used to reconstruct a mosquito germarium in order to characterize unknown events in early oogenesis. Findings from these studies, and many more like them, will soon unravel many of the mysteries surrounding the world of developmental biology.

Symmetry Breaking by Surface Blocking: Synthesis of Bimorphic Silver Nanoparticles, Nanoscale Fishes and Apples

Science.gov (United States)

Cathcart, Nicole; Kitaev, Vladimir

2016-09-01

A powerful approach to augment the diversity of well-defined metal nanoparticle (MNP) morphologies, essential for MNP advanced applications, is symmetry breaking combined with seeded growth. Utilizing this approach enabled the formation of bimorphic silver nanoparticles (bi-AgNPs) consisting of two shapes linked by one regrowth point. Bi-AgNPs were formed by using an adsorbing polymer, poly(acrylic acid), PAA, to block the surface of a decahedral AgNP seed and restricting growth of new silver to a single nucleation point. First, we have realized 2-D growth of platelets attached to decahedra producing nanoscale shapes reminiscent of apples, fishes, mushrooms and kites. 1-D bimorphic growth of rods (with chloride) and 3-D bimorphic growth of cubes and bipyramids (with bromide) were achieved by using halides to induce preferential (100) stabilization over (111) of platelets. Furthermore, the universality of the formation of bimorphic nanoparticles was demonstrated by using different seeds. Bi-AgNPs exhibit strong SERS enhancement due to regular cavities at the necks. Overall, the reported approach to symmetry breaking and bimorphic nanoparticle growth offers a powerful methodology for nanoscale shape design.

In-situ X-ray absorption spectroscopy analysis of capacity fade in nanoscale-LiCoO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Patridge, Christopher J. [NRC/NRL Cooperative Research Associate, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Love, Corey T., E-mail: corey.love@nrl.navy.mil [Chemistry Division, Code 6113, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Swider-Lyons, Karen E. [Chemistry Division, Code 6113, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Twigg, Mark E. [Electronics Science and Technology Division, Code 6812, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Ramaker, David E. [Chemistry Division, Code 6189, U.S. Naval Research laboratory, Washington, DC 20375 (United States)

2013-07-15

The local structure of nanoscale (∼10–40 nm) LiCoO{sub 2} is monitored during electrochemical cycling utilizing in-situ X-ray absorption spectroscopy (XAS). The high surface area of the LiCoO{sub 2} nanoparticles not only enhances capacity fade, but also provides a large signal from the particle surface relative to the bulk. Changes in the nanoscale LiCoO{sub 2} metal-oxide bond lengths, structural disorder, and chemical state are tracked during cycling by adapting the delta mu (Δμ) technique in complement with comprehensive extended X-ray absorption fine structure (EXAFS) modeling. For the first time, we use a Δμ EXAFS method, and by comparison of the difference EXAFS spectra, extrapolate significant coordination changes and reduction of cobalt species with cycling. This combined approach suggests Li–Co site exchange at the surface of the nanoscale LiCoO{sub 2} as a likely factor in the capacity fade and irreversible losses in practical, microscale LiCoO{sub 2}. - Graphical abstract: Electrochemical cycling of Li-ion batteries has strong impact on the structure and integrity of the cathode active material particularly near the surface/electrolyte interface. In developing a new method, we have used in-situ X-ray absorption spectroscopy during electrochemical cycling of nanoscale LiCoO{sub 2} to track changes during charge and discharge and between subsequent cycles. Using difference spectra, several small changes in Co-O bond length, Co-O and Co-Co coordination, and site exchange between Co and Li sites can be tracked. These methods show promise as a new technique to better understand processes which lead to capacity fade and loss in Li-ion batteries. - Highlights: • A new method is developed to understand capacity fade in Li-ion battery cathodes. • Structural changes are tracked during Li intercalation/deintercalation of LiCoO{sub 2}. • Surface structural changes are emphasized using nanoscale-LiCoO{sub 2} and difference spectra. • Full multiple

Spinel-structured surface layers for facile Li ion transport and improved chemical stability of lithium manganese oxide spinel

Energy Technology Data Exchange (ETDEWEB)

Lee, Hae Ri [Center for Energy Convergence Research, Korea Institute of Science Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701 (Korea, Republic of); Seo, Hyo Ree; Lee, Boeun; Cho, Byung Won [Center for Energy Convergence Research, Korea Institute of Science Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Lee, Kwan-Young [Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701 (Korea, Republic of); Oh, Si Hyoung, E-mail: sho74@kist.re.kr [Center for Energy Convergence Research, Korea Institute of Science Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)

2017-01-15

Graphical abstract: Strategically-designed spinel-structured nano-scale surface layer, LiM{sub x}Mn{sup IV}{sub 1−x}O{sub 4}, featuring a high Li{sup +} ion conductivity and a good chemical stability was applied on Al-doped LiMn{sub 2}O{sub 4} spinel for the drastic improvement of the electrochemical performance at the elevated temperature as a promising cathode material for lithium rechargeable batteries. - Highlights: • Spinel-structured surface layer with a high Li-ion conductivity and a good chemical stability was prepared. • Simple wet process was developed to apply nano-scale surface layer on aluminum doped lithium manganese oxide spinel. • The properties of nano-scale surface layer were characterized by analytical tools including GITT, HR-TEM and XAS. • Materials with surface coating layer exhibit an excellent electrochemical performance at the elevated temperature. - Abstract: Li-ion conducting spinel-structured oxide layer with a manganese oxidation state close to being tetravalent was prepared on aluminum-doped lithium manganese oxide spinel for improving the electrochemical performances at the elevated temperatures. This nanoscale surface layer provides a good ionic conduction path for lithium ion transport to the core and also serves as an excellent chemical barrier for protecting the high-capacity core material from manganese dissolution into the electrolyte. In this work, a simple wet process was employed to prepare thin LiAlMnO{sub 4} and LiMg{sub 0.5}Mn{sub 1.5}O{sub 4} layers on the surface of LiAl{sub 0.1}Mn{sub 1.9}O{sub 4}. X-ray absorption studies revealed an oxidation state close to tetravalent manganese on the surface layer of coated materials. Materials with these surface coating layers exhibited excellent capacity retentions superior to the bare material, without undermining the lithium ion transport characteristics and the high rate performances.

Extremely flexible nanoscale ultrathin body silicon integrated circuits on plastic.

Science.gov (United States)

Shahrjerdi, Davood; Bedell, Stephen W

2013-01-09

In recent years, flexible devices based on nanoscale materials and structures have begun to emerge, exploiting semiconductor nanowires, graphene, and carbon nanotubes. This is primarily to circumvent the existing shortcomings of the conventional flexible electronics based on organic and amorphous semiconductors. The aim of this new class of flexible nanoelectronics is to attain high-performance devices with increased packing density. However, highly integrated flexible circuits with nanoscale transistors have not yet been demonstrated. Here, we show nanoscale flexible circuits on 60 Å thick silicon, including functional ring oscillators and memory cells. The 100-stage ring oscillators exhibit the stage delay of ~16 ps at a power supply voltage of 0.9 V, the best reported for any flexible circuits to date. The mechanical flexibility is achieved by employing the controlled spalling technology, enabling the large-area transfer of the ultrathin body silicon devices to a plastic substrate at room temperature. These results provide a simple and cost-effective pathway to enable ultralight flexible nanoelectronics with unprecedented level of system complexity based on mainstream silicon technology.

Approaches for Achieving Superlubricity in Two-Dimensional Materials.

Science.gov (United States)

Berman, Diana; Erdemir, Ali; Sumant, Anirudha V

2018-03-27

Controlling friction and reducing wear of moving mechanical systems is important in many applications, from nanoscale electromechanical systems to large-scale car engines and wind turbines. Accordingly, multiple efforts are dedicated to design materials and surfaces for efficient friction and wear manipulation. Recent advances in two-dimensional (2D) materials, such as graphene, hexagonal boron nitride, molybdenum disulfide, and other 2D materials opened an era for conformal, atomically thin solid lubricants. However, the process of effectively incorporating 2D films requires a fundamental understanding of the atomistic origins of friction. In this review, we outline basic mechanisms for frictional energy dissipation during sliding of two surfaces against each other, and the procedures for manipulating friction and wear by introducing 2D materials at the tribological interface. Finally, we highlight recent progress in implementing 2D materials for friction reduction to near-zero values-superlubricity-across scales from nano- up to macroscale contacts.

Maintaining the pluripotency of mouse embryonic stem cells on gold nanoparticle layers with nanoscale but not microscale surface roughness

Science.gov (United States)

Lyu, Zhonglin; Wang, Hongwei; Wang, Yanyun; Ding, Kaiguo; Liu, Huan; Yuan, Lin; Shi, Xiujuan; Wang, Mengmeng; Wang, Yanwei; Chen, Hong

2014-05-01

Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction.Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold

Electrochemical Properties of High Surface Area Vanadium Oxide Aerogels

National Research Council Canada - National Science Library

Dong, Winny

2001-01-01

.... Traditional composite electrode structures have prevented truly quantitative analysis of surface area effects in nanoscale battery materials, as well as a study of their innate electrochemical behavior...

Nanoscale Mechanical Stimulation of Human Mesenchymal Stem Cells

Directory of Open Access Journals (Sweden)

H Nikukar

2014-05-01

We observed significant responses after 1 and 2-week stimulations in cell number, cell shapes and phenotypical markers. Microarray was performed for all groups. Cell count showed normal cell growth with stimulation. However, cell surface area, cell perimeter, and arboration after 1-week stimulation showed significant increases. Immunofluorescent studies have showed significant increase in osteocalcin production after stimulation. Conclusions: Nanoscale mechanical vibration showed significant changes in human mesenchymal stem cell behaviours. Cell morphology changed to become more polygonal and increased expression of the osteoblast markers were noted. These findings with gene regulation changes suggesting nanoscale mechanostimulation has stimulated osteoblastogenesis.  Keywords:  Mesenchymal, Nanoscale, Stem Cells.

Nano-scale patterning on sulfur terminated GaAs (0 0 1) surface by scanning tunneling microscope

International Nuclear Information System (INIS)

Yagishita, Yuki; Toda, Yusuke; Hirai, Masakazu; Fujishiro, Hiroki Inomata

2004-01-01

We perform nano-scale patterning on a sulfur (S) terminated GaAs (0 0 1) surface by a scanning tunneling microscope (STM) in ultra-high vacuum (UHV). A multi-layer of S deposited by using (NH 4 ) 2 S x solution is changed to a mono-layer after annealing at 560 deg. C for 15 h, which terminates the GaAs (0 0 1) surface. Groove structures with about 0.23 nm in depth and about 5 nm in width are patterned successfully on the S-terminated surface. We investigate dependences of both depth and width of the patterned groove on the tunneling current and the scanning speed of tip. It is observed that topmost S atoms are extracted together with first-layer Ga atoms, because of the larger binding energy of S-Ga bond

Grain Structure Control of Additively Manufactured Metallic Materials

Directory of Open Access Journals (Sweden)

Fuyao Yan

2017-11-01

Full Text Available Grain structure control is challenging for metal additive manufacturing (AM. Grain structure optimization requires the control of grain morphology with grain size refinement, which can improve the mechanical properties of additive manufactured components. This work summarizes methods to promote fine equiaxed grains in both the additive manufacturing process and subsequent heat treatment. Influences of temperature gradient, solidification velocity and alloy composition on grain morphology are discussed. Equiaxed solidification is greatly promoted by introducing a high density of heterogeneous nucleation sites via powder rate control in the direct energy deposition (DED technique or powder surface treatment for powder-bed techniques. Grain growth/coarsening during post-processing heat treatment can be restricted by presence of nano-scale oxide particles formed in-situ during AM. Grain refinement of martensitic steels can also be achieved by cyclic austenitizing in post-processing heat treatment. Evidently, new alloy powder design is another sustainable method enhancing the capability of AM for high-performance components with desirable microstructures.

Control surface wettability with nanoparticles from phase-change materials

NARCIS (Netherlands)

Ten Brink, G. H.; van het Hof, P. J.; Chen, B.; Sedighi, M.; Kooi, B. J.; Palasantzas, G.

2016-01-01

The wetting state of surfaces can be controlled physically from the highly hydrophobic to hydrophilic states using the amorphous-to-crystalline phase transition of Ge2Sb2Te5 (GST) nanoparticles as surfactant. Indeed, contact angle measurements show that by increasing the surface coverage of the

Visualizing copper assisted graphene growth in nanoscale

Science.gov (United States)

Rosmi, Mohamad Saufi; Yusop, Mohd Zamri; Kalita, Golap; Yaakob, Yazid; Takahashi, Chisato; Tanemura, Masaki

2014-01-01

Control synthesis of high quality large-area graphene on transition metals (TMs) by chemical vapor deposition (CVD) is the most fascinating approach for practical device applications. Interaction of carbon atoms and TMs is quite critical to obtain graphene with precise layer number, crystal size and structure. Here, we reveal a solid phase reaction process to achieve Cu assisted graphene growth in nanoscale by in-situ transmission electron microscope (TEM). Significant structural transformation of amorphous carbon nanofiber (CNF) coated with Cu is observed with an applied potential in a two probe system. The coated Cu particle recrystallize and agglomerate toward the cathode with applied potential due to joule heating and large thermal gradient. Consequently, the amorphous carbon start crystallizing and forming sp2 hybridized carbon to form graphene sheet from the tip of Cu surface. We observed structural deformation and breaking of the graphene nanoribbon with a higher applied potential, attributing to saturated current flow and induced Joule heating. The observed graphene formation in nanoscale by the in-situ TEM process can be significant to understand carbon atoms and Cu interaction. PMID:25523645

Improving Neural Recording Technology at the Nanoscale

Science.gov (United States)

Ferguson, John Eric

Neural recording electrodes are widely used to study normal brain function (e.g., learning, memory, and sensation) and abnormal brain function (e.g., epilepsy, addiction, and depression) and to interface with the nervous system for neuroprosthetics. With a deep understanding of the electrode interface at the nanoscale and the use of novel nanofabrication processes, neural recording electrodes can be designed that surpass previous limits and enable new applications. In this thesis, I will discuss three projects. In the first project, we created an ultralow-impedance electrode coating by controlling the nanoscale texture of electrode surfaces. In the second project, we developed a novel nanowire electrode for long-term intracellular recordings. In the third project, we created a means of wirelessly communicating with ultra-miniature, implantable neural recording devices. The techniques developed for these projects offer significant improvements in the quality of neural recordings. They can also open the door to new types of experiments and medical devices, which can lead to a better understanding of the brain and can enable novel and improved tools for clinical applications.

Nanoscale mechanical and tribological properties of fluorocarbon films grafted onto plasma-treated low-density polyethylene surfaces

International Nuclear Information System (INIS)

Cheng, Q; Komvopoulos, K

2012-01-01

Fluorocarbon (FC) films were grafted onto Ar plasma-treated low-density polyethylene (LDPE) surfaces by plasma polymerization and deposition. The evolution of the surface morphology of the grafted FC films was investigated at different scales with an atomic force microscope. Nanoscale sliding experiments performed with a surface force microscope provided insight into the nanotribological properties of Ar plasma-treated LDPE, with and without grafted FC films, in terms of applied normal load and number of sliding cycles. The observed trends are explained in the context of microstructure models accounting for morphological and structure changes at the LDPE surface due to the effects of plasma treatment (e.g., selective etching of amorphous phase, chain crosslinking and FC film grafting) and surface sliding (e.g., crystalline lamellae alignment along the sliding direction). Nanoindentation experiments elucidated the effect of plasma treatment on surface viscoelasticity and global contact stiffness. The results of this study demonstrate that plasma-assisted grafting of FC films is an effective surface modification method for tuning the nanomechanical/tribological properties of polymers. (paper)

Controlling Chemistry in Dynamic Nanoscale Systems

DEFF Research Database (Denmark)

Jesorka, Aldo; Lizana, Ludvig; Konkoli, Zoran

2011-01-01

Spatial organization and shape dynamics are inherent properties of biological cells and cell interiors. There are strong indications that these features are important for the in vivo control of reaction parameters in biochemical transformations. Nanofluidic model devices founded on surfactant...... of the concept. Controlled release of chol-DNA molecules from SU-8 surfaces gives the possibility to dynamically change surface and/or solution properties in micro and nanoreactor applications, opening access to stable 2D chemistry on surface-based devices with potential for easy interfacing with conventional...

Synthesis of nanoscale copper nitride thin film and modification of the surface under high electronic excitation.

Science.gov (United States)

Ghosh, S; Tripathi, A; Ganesan, V; Avasthi, D K

2008-05-01

Nanoscale (approximately 90 nm) Copper nitride (Cu3N) films are deposited on borosilicate glass and Si substrates by RF sputtering technique in the reactive environment of nitrogen gas. These films are irradiated with 200 MeV Au15+ ions from Pelletron accelerator in order to modify the surface by high electronic energy deposition of heavy ions. Due to irradiation (i) at incident ion fluence of 1 x 10(12) ions/cm2 enhancement of grains, (ii) at 5 x 10912) ions/cm2 mass transport on the films surface, (iii) at 2 x 10(13) ions/cm2 line-like features on Cu3N/glass and nanometallic structures on Cu3N/Si surface are observed. The surface morphology is examined by atomic force microscope (AFM). All results are explained on the basis of a thermal spike model of ion-solid interaction.

Enhancement of CNT/PET film adhesion by nano-scale modification for flexible all-solid-state supercapacitors

Science.gov (United States)

Kang, Yu Jin; Chung, Haegeun; Kim, Min-Seop; Kim, Woong

2015-11-01

We demonstrate the fabrication of high-integrity flexible supercapacitors using carbon nanotubes (CNTs), polyethylene terephthalate (PET) films, and ion gels. Although both CNTs and PET films are attractive materials for flexible electronics, they have poor adhesion properties. In this work, we significantly improve interfacial adhesion by introducing nanostructures at the interface of the CNT and PET layers. Simple reactive ion etching (RIE) of the PET substrates generates nano-scale roughness on the PET surface. RIE also induces hydrophilicity on the PET surface, which further enhances adhesive strength. The improved adhesion enables high integrity and excellent flexibility of the fabricated supercapacitors, demonstrated over hundreds of bending cycles. Furthermore, the supercapacitors show good cyclability with specific capacitance retention of 87.5% after 10,000 galvanostatic charge-discharge (GCD) cycles. Our demonstration may be important for understanding interfacial adhesion properties in nanoscale and for producing flexible, high-integrity, high-performance energy storage systems.

Nanoscale synthesis and characterization of graphene-based objects

Directory of Open Access Journals (Sweden)

Daisuke Fujita

2011-01-01

Full Text Available Graphene-based nano-objects such as nanotrenches, nanowires, nanobelts and nanoscale superstructures have been grown by surface segregation and precipitation on carbon-doped mono- and polycrystalline nickel substrates in ultrahigh vacuum. The dominant morphologies of the nano-objects were nanowire and nanosheet. Nucleation of graphene sheets occurred at surface defects such as step edges and resulted in the directional growth of nanowires. Surface analysis by scanning tunneling microscopy (STM has clarified the structure and functionality of the novel nano-objects at atomic resolution. Nanobelts were detected consisting of bilayer graphene sheets with a nanoscale width and a length of several microns. Moiré patterns and one-dimensional reconstruction were observed on multilayer graphite terraces. As a useful functionality, application to repairable high-resolution STM probes is demonstrated.

Nano-scale surface modification of materials with slow, highly charged ion beams

International Nuclear Information System (INIS)

Sakurai, M.; Tona, M.; Takahashi, S.; Watanabe, H.; Nakamura, N.; Yoshiyasu, N.; Yamada, C.; Ohtani, S.; Sakaue, H.A.; Kawase, Y.; Mitsumori, K.; Terui, T.; Mashiko, S.

2007-01-01

Some results on surface modification of Si and graphite with highly charged ions (HCIs) are presented. Modified surfaces were observed using scanning tunneling microscopy. Crater-like structure with a diameter in nm region is formed on a Si(1 1 1)-(7 x 7) surface by the incidence of a single HCI. The protrusion structure is formed on a highly oriented pyrolytic graphite surface on the other hand, and the structure becomes an active site for molecular adsorption. A new, intense HCI source and an experimental apparatus are under development in order to process and observe aligned nanostructures created by the impact of collimated HCI beam

Influence of surface treatment on preparing nanosized TiO2 supported on carbon nanotubes

International Nuclear Information System (INIS)

Wang Shuo; Ji Lijun; Wu Bin; Gong Qianming; Zhu Yuefeng; Liang Ji

2008-01-01

In this paper, nanosize titanium dioxide (TiO 2 ) deposited on pristine and acid treated carbon nanotubes (CNTs) were prepared by a modified sol-gel method. The nanoscale materials were extensively characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and Raman spectra. The results indicated that about 6.8 nm TiO 2 nanoparticles were successfully deposited on acid-treated CNTs surface homogeneously and densely, which was smaller than TiO 2 coated on pristine CNTs. The surface state of CNTs was a critical factor in obtaining a homogeneous distribution of nanoscale TiO 2 particles. Acid oxidization could etch the surface of CNTs and introduce functional groups, which were beneficial to controllable homogeneous deposition. The TiO 2 coated on acid-treated CNTs was used as photocatalyst for Reactive Brilliant Red X-3B dye degradation under UV irradiation, which showed higher efficiency than that of TiO 2 coated on pristine CNTs and commercial photocatalyst P25.

Pinning of the Contact Line during Evaporation on Heterogeneous Surfaces: Slowdown or Temporary Immobilization? Insights from a Nanoscale Study.

Science.gov (United States)

Zhang, Jianguo; Müller-Plathe, Florian; Leroy, Frédéric

2015-07-14

The question of the effect of surface heterogeneities on the evaporation of liquid droplets from solid surfaces is addressed through nonequilibrium molecular dynamics simulations. The mechanism behind contact line pinning which is still unclear is discussed in detail on the nanoscale. Model systems with the Lennard-Jones interaction potential were employed to study the evaporation of nanometer-sized cylindrical droplets from a flat surface. The heterogeneity of the surface was modeled through alternating stripes of equal width but two chemical types. The first type leads to a contact angle of 67°, and the other leads to a contact angle of 115°. The stripe width was varied between 2 and 20 liquid-particle diameters. On the surface with the narrowest stripes, evaporation occurred at constant contact angle as if the surface was homogeneous, with a value of the contact angle as predicted by the regular Cassie-Baxter equation. When the width was increased, the contact angle oscillated during evaporation between two boundaries whose values depend on the stripe width. The evaporation behavior was thus found to be a direct signature of the typical size of the surface heterogeneity domains. The contact angle both at equilibrium and during evaporation could be predicted from a local Cassie-Baxter equation in which the surface composition within a distance of seven fluid-particle diameters around the contact line was considered, confirming the local nature of the interactions that drive the wetting behavior of droplets. More importantly, we propose a nanoscale explanation of pinning during evaporation. Pinning should be interpreted as a drastic slowdown of the contact line dynamics rather than a complete immobilization of it during a transition between two contact angle boundaries.

Direct Probing of Polarization Charge at Nanoscale Level

Energy Technology Data Exchange (ETDEWEB)

Kwon, Owoong [Sungkyunkwan Univ., Suwon (Republic of Korea). School of Advanced Materials and Engineering; Seol, Daehee [Sungkyunkwan Univ., Suwon (Republic of Korea). School of Advanced Materials and Engineering; Lee, Dongkyu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Han, Hee [Korea Research Inst. of Standards and Science (KRISS), Daejeon (South Korea); Lindfors-Vrejoiu, Ionela [Univ. of Cologne (Germany). Physics Inst.; Lee, Woo [Korea Research Inst. of Standards and Science (KRISS), Daejeon (South Korea); Jesse, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences; Lee, Ho Nyung [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Kalinin, Sergei V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences; Alexe, Marin [Univ. of Warwick, Coventry (United Kingdom). Dept. of Physics; Kim, Yunseok [Sungkyunkwan Univ., Suwon (Republic of Korea). School of Advanced Materials and Engineering

2017-11-14

Ferroelectric materials possess spontaneous polarization that can be used for multiple applications. Owing to a long-term development of reducing the sizes of devices, the preparation of ferroelectric materials and devices is entering the nanometer-scale regime. In order to evaluate the ferroelectricity, there is a need to investigate the polarization charge at the nanoscale. Nonetheless, it is generally accepted that the detection of polarization charges using a conventional conductive atomic force microscopy (CAFM) without a top electrode is not feasible because the nanometer-scale radius of an atomic force microscopy (AFM) tip yields a very low signal-to-noise ratio. But, the detection is unrelated to the radius of an AFM tip and, in fact, a matter of the switched area. In this work, the direct probing of the polarization charge at the nanoscale is demonstrated using the positive-up-negative-down method based on the conventional CAFM approach without additional corrections or circuits to reduce the parasitic capacitance. The polarization charge densities of 73.7 and 119.0 µC cm^-2 are successfully probed in ferroelectric nanocapacitors and thin films, respectively. The results we obtained show the feasibility of the evaluation of polarization charge at the nanoscale and provide a new guideline for evaluating the ferroelectricity at the nanoscale.

Two-dimensional linear elasticity theory of magneto-electro-elastic plates considering surface and nonlocal effects for nanoscale device applications

Science.gov (United States)

Wang, Wenjun; Li, Peng; Jin, Feng

2016-09-01

A novel two-dimensional linear elastic theory of magneto-electro-elastic (MEE) plates, considering both surface and nonlocal effects, is established for the first time based on Hamilton’s principle and the Lee plate theory. The equations derived are more general, suitable for static and dynamic analyses, and can also be reduced to the piezoelectric, piezomagnetic, and elastic cases. As a specific application example, the influences of the surface and nonlocal effects, poling directions, piezoelectric phase materials, volume fraction, damping, and applied magnetic field (i.e., constant applied magnetic field and time-harmonic applied magnetic field) on the magnetoelectric (ME) coupling effects are first investigated based on the established two-dimensional plate theory. The results show that the ME coupling coefficient has an obvious size-dependent characteristic owing to the surface effects, and the surface effects increase the ME coupling effects significantly when the plate thickness decreases to its critical thickness. Below this critical thickness, the size-dependent effect is obvious and must be considered. In addition, the output power density of a magnetic energy nanoharvester is also evaluated using the two-dimensional plate theory obtained, with the results showing that a relatively larger output power density can be achieved at the nanoscale. This study provides a mathematical tool which can be used to analyze the mechanical properties of nanostructures theoretically and numerically, as well as evaluating the size effect qualitatively and quantitatively.

Roughness modification of surfaces treated by a pulsed dielectric barrier discharge

CERN Document Server

Dumitrascu, N; Apetroaei, N; Popa, G

2002-01-01

Local modifications of surface roughness are very important in many applications, as this surface property is able to generate new mechano-physical characteristics of a large category of materials. Roughness is one of the most important parameters used to characterize and control the surface morphology, and techniques that allow modifying and controlling the surface roughness present increasing interest. In this respect we propose the dielectric barrier discharge (DBD) as a simple and low cost method that can be used to induce controlled roughness on various surfaces in the nanoscale range. DBD is produced in helium, at atmospheric pressure, by a pulsed high voltage, 28 kV peak to peak, 13.5 kHz frequency and 40 W power. This type of discharge is a source of energy capable of modifying the physico-chemical properties of the surfaces without affecting their bulk properties. The discharge is characterized by means of electrical probes and, in order to analyse the heat transfer rate from the discharge to the tre...

Oxide films at the nanoscale: new structures, new functions, and new materials.

Science.gov (United States)

Giordano, Livia; Pacchioni, Gianfranco

2011-11-15

We all make use of oxide ultrathin films, even if we are unaware of doing so. They are essential components of many common devices, such as mobile phones and laptops. The films in these ubiquitous electronics are composed of silicon dioxide, an unsurpassed material in the design of transistors. But oxide films at the nanoscale (typically just 10 nm or less in thickness) are integral to many other applications. In some cases, they form under normal reactive conditions and confer new properties to a material: one example is the corrosion protection of stainless steel, which is the result of a passive film. A new generation of devices for energy production and communications technology, such as ferroelectric ultrathin film capacitors, tunneling magnetoresistance sensors, solar energy materials, solid oxide fuel cells, and many others, are being specifically designed to exploit the unusual properties afforded by reduced oxide thickness. Oxide ultrathin films also have tremendous potential in chemistry, representing a rich new source of catalytic materials. About 20 years ago, researchers began to prepare model systems of truly heterogeneous catalysts based on thin oxide layers grown on single crystals of metal. Only recently, however, was it realized that these systems may behave quite differently from their corresponding bulk oxides. One of the phenomena uncovered is the occurrence of a spontaneous charge transfer from the metal support to an adsorbed species through the thin insulating layer (or vice versa). The importance of this property is clear: conceptually, the activation and bond breaking of adsorbed molecules begin with precisely the same process, electron transfer into an antibonding orbital. But electron transfer can also be harnessed to make a supported metal particle more chemically active, increase its adhesion energy, or change its shape. Most importantly, the basic principles underlying electron transfer and other phenomena (such as structural

Report of the 1st RCM on ''Nanoscale radiation engineering of advanced materials for potential biomedical applications''. Working document

Energy Technology Data Exchange (ETDEWEB)

NONE

2009-07-01

There are critical needs for advanced materials in the area of biomaterial engineering, primarily in generating biomaterials of enhanced specific functionalities, improved biocompatibility, and minimal natural rejection but with enhanced interfacial adhesion. These can be achieved by introduction of proper functionalities at the nanoscale dimensions and radiation techniques are uniquely suited for such a task, due to their favorable characteristics, and in most cases, not possible by other methods of synthesis. Accordingly, many of the developing and developed Member States have an interest in creating advanced materials for various health-care applications using a wide array of radiation sources and their broad expertise. The proposal for this CRP was formulated based on the requests and information received from the member states and the conclusions and recommendations of the Consultant’s meeting on “Advanced Materials on the Nano-scale Synthesized by Radiation-Induced Processes”, held on 10-14 December 2007, in Vienna. Based on these conclusions, this CRP aims to support MS to develop methodologies for the use of radiation in the synthesis, modification, and characterization of nanomaterials - nanogels, nanoparticles, nanovehicles, nanoporous membranes, and surfaces with enhanced biocompatibility for potential biomedical applications, such as cell-sheet engineering and artificial tissue construction; diagnostics and imaging; and drug delivery. Additionally, this CRP facilitates networking between radiation technologists and biomedical scientists for the development of such applications. The CRP generated a huge interest, but due to funding constrains, many good proposals had to be rejected. The first RCM of the CRP was convened in Vienna on 30 March - 03 April 2009. It was attended by 14 representatives and two observers. The participants presented and discussed the status of the field, the needs for further research, and various application possibilities

Report of the 1st RCM on ''Nanoscale radiation engineering of advanced materials for potential biomedical applications''. Working document

International Nuclear Information System (INIS)

2009-01-01

There are critical needs for advanced materials in the area of biomaterial engineering, primarily in generating biomaterials of enhanced specific functionalities, improved biocompatibility, and minimal natural rejection but with enhanced interfacial adhesion. These can be achieved by introduction of proper functionalities at the nanoscale dimensions and radiation techniques are uniquely suited for such a task, due to their favorable characteristics, and in most cases, not possible by other methods of synthesis. Accordingly, many of the developing and developed Member States have an interest in creating advanced materials for various health-care applications using a wide array of radiation sources and their broad expertise. The proposal for this CRP was formulated based on the requests and information received from the member states and the conclusions and recommendations of the Consultant’s meeting on “Advanced Materials on the Nano-scale Synthesized by Radiation-Induced Processes”, held on 10-14 December 2007, in Vienna. Based on these conclusions, this CRP aims to support MS to develop methodologies for the use of radiation in the synthesis, modification, and characterization of nanomaterials - nanogels, nanoparticles, nanovehicles, nanoporous membranes, and surfaces with enhanced biocompatibility for potential biomedical applications, such as cell-sheet engineering and artificial tissue construction; diagnostics and imaging; and drug delivery. Additionally, this CRP facilitates networking between radiation technologists and biomedical scientists for the development of such applications. The CRP generated a huge interest, but due to funding constrains, many good proposals had to be rejected. The first RCM of the CRP was convened in Vienna on 30 March - 03 April 2009. It was attended by 14 representatives and two observers. The participants presented and discussed the status of the field, the needs for further research, and various application possibilities

Surfaces and interfaces of electronic materials

CERN Document Server

Brillson, Leonard J

2012-01-01

An advanced level textbook covering geometric, chemical, and electronic structure of electronic materials, and their applications to devices based on semiconductor surfaces, metal-semiconductor interfaces, and semiconductor heterojunctions. Starting with the fundamentals of electrical measurements on semiconductor interfaces, it then describes the importance of controlling macroscopic electrical properties by atomic-scale techniques. Subsequent chapters present the wide range of surface and interface techniques available to characterize electronic, optical, chemical, and structural propertie

Bio-inspired water repellent surfaces produced by ultrafast laser structuring of silicon

International Nuclear Information System (INIS)

Barberoglou, M.; Zorba, V.; Stratakis, E.; Spanakis, E.; Tzanetakis, P.; Anastasiadis, S.H.; Fotakis, C.

2009-01-01

We report here an efficient method for preparing stable superhydrophobic and highly water repellent surfaces by irradiating silicon wafers with femtosecond laser pulses and subsequently coating them with chloroalkylsilane monolayers. By varying the laser pulse fluence on the surface one can successfully control its wetting properties via a systematic and reproducible variation of roughness at micro- and nano-scale, which mimics the topology of natural superhydrophobic surfaces. The self-cleaning and water repellent properties of these artificial surfaces are investigated. It is found that the processed surfaces are among the most water repellent surfaces ever reported. These results may pave the way for the implementation of laser surface microstructuring techniques for the fabrication of superhydrophobic and self-cleaning surfaces in different kinds of materials as well

Molecular tailoring of solid surfaces

Energy Technology Data Exchange (ETDEWEB)

Evenson, Simon Alan

1997-07-01

The overall performance of a material can be dramatically improved by tailoring its surface at the molecular level. The aim of this project was to develop a universal technique for attaching dendrimers (well-defined, nanoscale, functional polymers) and Jeffamines (high molecular weight polymer chains) to the surface of any shaped solid substrate. This desire for controlled functionalization is ultimately driven by the need to improve material compatibility in various biomedical applications. Atomic force microscopy (AFM) was used initially to study the packing and structure of Langmuir-Blodgett films on surfaces, and subsequently resulted in the first visualization of individual, spherically shaped, nanoscopic polyamidoamine dendrimers. The next goal was to develop a methodology for attaching such macromolecules to inert surfaces. Thin copolymer films were deposited onto solid substrates to produce materials with a fixed concentration of surface anhydride groups. Vapor-phase functionalization reactions were then carried out with trifluorinated amines to confirm the viability of this technique to bond molecules to surfaces. Finally, pulsed plasma polymerization of maleic anhydride took this approach one stage further, by forming well-adhered polymer films containing a predetermined concentration of reactive anhydride groups. Subsequent functionalization reactions led to the secure attachment of dendrimers and Jeffamines at any desired packing density. An alternative route to biocompatibilization used 1,2-ethanedithiol to yield thiolated surfaces containing very high polymeric sulfur : carbon ratios. (author)

Molecular tailoring of solid surfaces

International Nuclear Information System (INIS)

Evenson, Simon Alan

1997-01-01

The overall performance of a material can be dramatically improved by tailoring its surface at the molecular level. The aim of this project was to develop a universal technique for attaching dendrimers (well-defined, nanoscale, functional polymers) and Jeffamines (high molecular weight polymer chains) to the surface of any shaped solid substrate. This desire for controlled functionalization is ultimately driven by the need to improve material compatibility in various biomedical applications. Atomic force microscopy (AFM) was used initially to study the packing and structure of Langmuir-Blodgett films on surfaces, and subsequently resulted in the first visualization of individual, spherically shaped, nanoscopic polyamidoamine dendrimers. The next goal was to develop a methodology for attaching such macromolecules to inert surfaces. Thin copolymer films were deposited onto solid substrates to produce materials with a fixed concentration of surface anhydride groups. Vapor-phase functionalization reactions were then carried out with trifluorinated amines to confirm the viability of this technique to bond molecules to surfaces. Finally, pulsed plasma polymerization of maleic anhydride took this approach one stage further, by forming well-adhered polymer films containing a predetermined concentration of reactive anhydride groups. Subsequent functionalization reactions led to the secure attachment of dendrimers and Jeffamines at any desired packing density. An alternative route to biocompatibilization used 1,2-ethanedithiol to yield thiolated surfaces containing very high polymeric sulfur : carbon ratios. (author)

Surface self-organization in multilayer film coatings

Science.gov (United States)

Shuvalov, Gleb M.; Kostyrko, Sergey A.

2017-12-01

It is a recognized fact that during film deposition and subsequent thermal processing the film surface evolves into an undulating profile. Surface roughness affects many important aspects in the engineering application of thin film materials such as wetting, heat transfer, mechanical, electromagnetic and optical properties. To accurately control the morphological surface modifications at the micro- and nanoscale and improve manufacturing techniques, we design a mathematical model of the surface self-organization process in multilayer film materials. In this paper, we consider a solid film coating with an arbitrary number of layers under plane strain conditions. The film surface has a small initial perturbation described by a periodic function. It is assumed that the evolution of the surface relief is governed by surface and volume diffusion. Based on Gibbs thermodynamics and linear theory of elasticity, we present a procedure for constructing a governing equation that gives the amplitude change of the surface perturbation with time. A parametric study of the evolution equation leads to the definition of a critical undulation wavelength that stabilizes the surface. As a numerical result, the influence of geometrical and physical parameters on the morphological stability of an isotropic two-layered film coating is analyzed.

Surface physics of materials materials science and technology

CERN Document Server

Blakely, J M

2013-01-01

Surface Physics of Materials presents accounts of the physical properties of solid surfaces. The book contains selected articles that deal with research emphasizing surface properties rather than experimental techniques in the field of surface physics. Topics discussed include transport of matter at surfaces; interaction of atoms and molecules with surfaces; chemical analysis of surfaces; and adhesion and friction. Research workers, teachers and graduate students in surface physics, and materials scientist will find the book highly useful.

A nanoscale friction investigation during the manipulation of nanoparticles in controlled environments

International Nuclear Information System (INIS)

Palacio, Manuel; Bhushan, Bharat

2008-01-01

Future micro/nanodevices will contain very small features such that liquid lubrication is not practical and inherent lubricity is needed. In this study, a nanoscale friction investigation was carried out during the manipulation of Au and SiO 2 nanoparticles on silicon using atomic force microscopy (AFM). Nanoparticle sliding was characterized by quantifying the lateral force associated with the AFM tip twisting as it hits the particle edge. The friction force varies with particle area and humidity, illustrating how meniscus forces on nanoparticles affect friction. A large tip slid on the nanoparticle-coated surface exhibited friction reduction due to nanoparticle sliding and contact area reduction

Surface interactions between nanoscale iron and organic material: Potential uses in water treatment process units

Science.gov (United States)

Storms, Max

Membrane systems are among the primary emergent technologies in water treatment process units due to their ease of use, small physical footprint, and high physical rejection. Membrane fouling, the phenomena by which membranes become clogged or generally soiled, is an inhibitor to optimal efficiency in membrane systems. Novel, composite, and modified surface materials must be investigated to determine their efficacy in improving fouling behavior. Ceramic membranes derived from iron oxide nanoparticles called ferroxanes were coated with a superhydrophillic, zwitterionic polymer called poly (sulfobetaine methacrylate) (polySBMA) to form a composite ceramic-polymeric membrane. Membrane samples with and without polySBMA coating were subjected to fouling with a bovine serum albumin solution and fouling was observed by measuring permeate flux at 10 mL intervals. Loss of polySBMA was measured using total organic carbon analysis, and membrane samples were characterized using x-ray diffraction, scanning electron microscopy, and optical profilometry. The coated membrane samples decreased initial fouling rate by 27% and secondary fouling rate by 24%. Similarly, they displayed a 30% decrease in irreversible fouling during the initial fouling stage, and a 27% decrease in irreversible fouling in the secondary fouling stage; however, retention of polySBMA sufficient for improved performance was not conclusive. The addition of chemical disinfectants into drinking water treatment processes results in the formation of compounds called disinfection by-products (DBPs). The formation of DBPs occurs when common chemical disinfectants (i.e. chlorine) react with organic material. The harmful effects of DBP exposure require that they be monitored and controlled for public safety. This work investigated the ability of nanostructured hematite derived from ferroxane nanoparticles to remove organic precursors to DBPs in the form of humic acid via adsorption processes. The results show that p

Kinetics of the melting front movement in process of centrifugal induction surfacing of powder material with nanoscale modificaters

Science.gov (United States)

Sasnouski, I.; Kurylionak, A.

2018-03-01

For solving the problem of improving the powder coatings modified by nanostructure components obtained by induction surfacing method tribological characteristics it is necessary to study the kinetics of the powdered layer melting and define the minimum time of melting. For powdered layer predetermined temperature maintenance at sintering mode stage it is required to determine the temperature difference through blank thickness of the for one hundred-day of the define the warm-up swing on of the stocking up by solving the thermal conductivity stationary problem for quill (hollow) cylinder with internal heat source. Herewith, since in practice thickness of the cylinder wall is much less then its diameter and the temperature difference is comparatively small, the thermal conductivity dependence upon the temperature can be treated as negligible. As it was shown by our previous studies, in the induction heating process under powdered material centrifugal surfacing (i.e. before achieving the melting temperature) the temperature distribution in powdered layer thickness may be considered even. Hereinafter, considering the blank part induction heating process quasi-stationarity under Fo big values, it is possible to consider its internal surface heating as developing with constant velocity. As a result of development the melting front movement mathematical model in a powdered material with nanostructure modifiers the minimum surfacing time is defined. It allows to minimize negative impact of thermal influence on formation of applied coating structure, to raise productivity of the process, to lower power inputs and to ensure saving of nonferrous and high alloys by reducing the allowance for machining. The difference of developed mathematical model of melting front movement from previously known is that the surface temperature from which the heat transfer occures is a variable and varies with a time after the linear law.

Nanoscale Characterization for the Classroom

International Nuclear Information System (INIS)

Carroll, D.L.

1999-01-01

This report describes the development of a semester course in 'nano-scale characterization'. The interdisciplinary course is opened to both advanced undergraduate and graduate students with a standard undergraduate preparation in Materials Science, Chemistry, or Physics. The approach is formal rather than the typical 'research seminar' and has a laboratory component

Tribology of Si/SiO2 in humid air: transition from severe chemical wear to wearless behavior at nanoscale.

Science.gov (United States)

Chen, Lei; He, Hongtu; Wang, Xiaodong; Kim, Seong H; Qian, Linmao

2015-01-13

Wear at sliding interfaces of silicon is a main cause for material loss in nanomanufacturing and device failure in microelectromechanical system (MEMS) applications. However, a comprehensive understanding of the nanoscale wear mechanisms of silicon in ambient conditions is still lacking. Here, we report the chemical wear of single crystalline silicon, a material used for micro/nanoscale devices, in humid air under the contact pressure lower than the material hardness. A transmission electron microscopy (TEM) analysis of the wear track confirmed that the wear of silicon in humid conditions originates from surface reactions without significant subsurface damages such as plastic deformation or fracture. When rubbed with a SiO2 ball, the single crystalline silicon surface exhibited transitions from severe wear in intermediate humidity to nearly wearless states at two opposite extremes: (a) low humidity and high sliding speed conditions and (b) high humidity and low speed conditions. These transitions suggested that at the sliding interfaces of Si/SiO2 at least two different tribochemical reactions play important roles. One would be the formation of a strong "hydrogen bonding bridge" between hydroxyl groups of two sliding interfaces and the other the removal of hydroxyl groups from the SiO2 surface. The experimental data indicated that the dominance of each reaction varies with the ambient humidity and sliding speed.

Topology optimization for nano-scale heat transfer

DEFF Research Database (Denmark)

Evgrafov, Anton; Maute, Kurt; Yang, Ronggui

2009-01-01

We consider the problem of optimal design of nano-scale heat conducting systems using topology optimization techniques. At such small scales the empirical Fourier's law of heat conduction no longer captures the underlying physical phenomena because the mean-free path of the heat carriers, phonons...... in our case, becomes comparable with, or even larger than, the feature sizes of considered material distributions. A more accurate model at nano-scales is given by kinetic theory, which provides a compromise between the inaccurate Fourier's law and precise, but too computationally expensive, atomistic...

Solvothermal coating LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} microspheres with nanoscale Li{sub 2}TiO{sub 3} shell for long lifespan Li-ion battery cathode materials

Energy Technology Data Exchange (ETDEWEB)

Wu, Naiteng; Wu, Hao; Liu, Heng; Zhang, Yun, E-mail: y_zhang@scu.edu.cn

2016-04-25

LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} (NCA) microspheres covered by a nanoscale Li{sub 2}TiO{sub 3}-based shell were synthesized by a facile strategy based on a solvothermal pre-coating treatment combined with a post-sintering lithiation process. The morphology, structure and composition of the Li{sub 2}TiO{sub 3}-coated NCA samples were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning scanning electron microscope (SEM) with an energy-dispersive X-ray spectroscope (EDS), and transmission electron microscopy (TEM). Owing to the complete, uniform and nanoscale Li{sub 2}TiO{sub 3} coating shell, the resultant surface-modified NCA microspheres used as Li-ion battery cathode materials manifest remarkably enhanced cycling performances, attaining 94% and 84% capacity retention after 200 and 400 cycles at 0.5 C, respectively, which is much better than the pristine NCA counterpart (60% retention, 200 cycles). More impressively, the surface-modified NCA also shows an intriguing storage stability. After being stored at 30 °C for 50 days, the coated NCA-based cells are subjected to be cycled both at room and elevated temperatures, in which the aged cells can still remain 84% capacity retention after 200 cycles at 25 °C and 77% capacity retention after 200 cycles at 55 °C, respectively. All these results demonstrate that the Li{sub 2}TiO{sub 3}-coated LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} microsphere is a promising cathode material for Li-ion batteries with long lifespan. - Graphical abstract: Nanoscale Li{sub 2}TiO{sub 3}-based shell encapsulated LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} (NCA) microspheres are fabricated through a solvothermal pre-coating treatment combined with post-lithiation process. The surface-coated NCA as cathode materials shows a remarkably enhanced cycling performance and storage stability for long lifespan Li-ion batteries. - Highlights: • Li{sub 2}TiO{sub 3} is used as coating

Unraveling atomic-level self-organization at the plasma-material interface

Science.gov (United States)

Allain, J. P.; Shetty, A.

2017-07-01

The intrinsic dynamic interactions at the plasma-material interface and critical role of irradiation-driven mechanisms at the atomic scale during exposure to energetic particles require a priori the use of in situ surface characterization techniques. Characterization of ‘active’ surfaces during modification at atomic-scale levels is becoming more important as advances in processing modalities are limited by an understanding of the behavior of these surfaces under realistic environmental conditions. Self-organization from exposure to non-equilibrium and thermalized plasmas enable dramatic control of surface morphology, topography, composition, chemistry and structure yielding the ability to tune material properties with an unprecedented level of control. Deciphering self-organization mechanisms of nanoscale morphology (e.g. nanodots, ripples) and composition on a variety of materials including: compound semiconductors, semiconductors, ceramics, polymers and polycrystalline metals via low-energy ion-beam assisted plasma irradiation are critical to manipulate functionality in nanostructured systems. By operating at ultra-low energies near the damage threshold, irradiation-driven defect engineering can be optimized and surface-driven mechanisms controlled. Tunability of optical, electronic, magnetic and bioactive properties is realized by reaching metastable phases controlled by atomic-scale irradiation-driven mechanisms elucidated by novel in situ diagnosis coupled to atomistic-level computational tools. Emphasis will be made on tailored surface modification from plasma-enhanced environments on particle-surface interactions and their subsequent modification of hard and soft matter interfaces. In this review, we examine current trends towards in situ and in operando surface and sub-surface characterization to unravel atomic-scale mechanisms at the plasma-material interface. This work will emphasize on recent advances in the field of plasma and ion

Nano-scale pattern formation on the surface of HgCdTe produced by ion bombardment

Energy Technology Data Exchange (ETDEWEB)

Smirnov, A.B.; Gudymenko, A.I.; Kladko, V.P.; Korchevyi, A.A.; Savkina, R.K.; Sizov, F.F.; Udovitska, R.S. [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kiev (Ukraine)

2015-08-15

Presented in this work are the results concerning formation of nano-scale patterns on the surface of a ternary compound Hg{sub 1-x}Cd{sub x}Te (x ∝ 0.223). Modification of this ternary chalcogenide semiconductor compound was performed using the method of oblique-incidence ion bombardment with silver ions, which was followed by low-temperature treatment. The energy and dose of implanted ions were 140 keV and 4.8 x 10{sup 13} cm{sup -2}, respectively. Atomic force microscopy methods were used for the surface topography characterization. The structural properties of MCT-based structure was analyzed using double and triple crystal X-ray diffraction to monitor the disorder and strain of the implanted region as a function of processing conditions. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

EDITORIAL: Mastering matter at the nanoscale Mastering matter at the nanoscale

Science.gov (United States)

Forchel, Alfred

2009-10-01

In the early 1980s, the development of scanning probe techniques gave scientists a titillating view of surfaces with nanometre resolution, igniting activity in research at the nanoscale. Images at unprecedented resolution were unveiled with the aid of various types of nanosized tips, including the scanning tunnelling (Binnig G, Rohrer H, Gerber C and Weibel E 1982 Appl. Phys. Lett. 40 178-80) the atomic force (Binnig G, Quate C F and Gerber C 1986 Phys. Rev. Lett. 56 930-3) and the near-field scanning microscopes (Dürig U, Pohl D W and Rohner F 1986 J. Appl. Phys. 59 3318-27). From the magnitude of tunnelling currents between conductive surfaces and van der Waals forces between dielectrics to the non-propagating evanescent fields at illuminated surfaces, a range of signal responses were harnessed enabling conductive, dielectric and even biological systems to be imaged. But it may be argued that it was the ability to manipulate matter at the nanoscale that really empowered nanotechnology. From the inception of the scanning probe revolution, these probes used to image nanostructures were also discovered to be remarkable tools for the manipulation of nanoparticles. Insights into the mechanism behind such processes were reported by a team of researchers at UCLA over ten years ago in 1998 (Baur C et al 1998 Nanotechnology 9 360-4). In addition, lithography and etching methods of patterning continue to evolve into ever more sophisticated techniques for exerting design over the structure of matter at the nanoscale. These so-called top-down methods, such as photolithography, electron-beam lithography and nanoimprint lithography, now provide control over features with a resolution of a few nanometres. Bottom-up fabrication techniques that exploit the self-assembly of constituents into desired structures have also stimulated extensive research. These techniques, such as the electrochemically assembled quantum-dot arrays reported by a team of US reasearchers over ten years

Nanoscale structural order from the atomic pair distribution function (PDF): There's plenty of room in the middle

International Nuclear Information System (INIS)

Billinge, Simon J.L.

2008-01-01

Emerging materials of scientific and technological interest are generally complex and often nanostructured: they have atomic orderings that extend on nanometer length-scales. These can be discrete nanoparticles; bulk crystals with nanoscale chemical or displacive order within them; mesoporous materials that are bulk materials containing nanoscale holes; and nanocomposites that are intimate heterogeneous mixtures of nano-sized constituents. As always, a quantitative knowledge of the atomic structure within these materials is a prerequisite to understanding and engineering their properties. Traditional crystallographic methods for obtaining this information break down at the nanoscale, sometimes referred to as 'the nanostructure problem'. We describe here some emerging methods for studying nanoscale structure. We present some examples of recent successes. Finally, we discuss future directions and opportunities and draw attention to limitations and potential problems. -

Superhydrophobic surfaces

Science.gov (United States)

Wang, Evelyn N; McCarthy, Matthew; Enright, Ryan; Culver, James N; Gerasopoulos, Konstantinos; Ghodssi, Reza

2015-03-24

Surfaces having a hierarchical structure--having features of both microscale and nanoscale dimensions--can exhibit superhydrophobic properties and advantageous condensation and heat transfer properties. The hierarchical surfaces can be fabricated using biological nanostructures, such as viruses as a self-assembled nanoscale template.

Surface profile gradient in amorphous Ta{sub 2}O{sub 5} semi conductive layers regulates nanoscale electric current stability

Energy Technology Data Exchange (ETDEWEB)

Cefalas, A.C., E-mail: ccefalas@eie.gr [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635 (Greece); Kollia, Z.; Spyropoulos-Antonakakis, N.; Gavriil, V. [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635 (Greece); Christofilos, D.; Kourouklis, G. [Physics Division, School of Technology, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Semashko, V.V.; Pavlov, V. [Kazan Federal University, Institute of Physics, 18 Kremljovskaja str., Kazan 420008 (Russian Federation); Sarantopoulou, E. [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635 (Greece); Kazan Federal University, Institute of Physics, 18 Kremljovskaja str., Kazan 420008 (Russian Federation)

2017-02-28

Highlights: • The work links the surface morphology of amorphous semiconductors with both their electric-thermal properties and current stability at the nanoscale (<1 μm). • Measured high correlation value between surface morphological spatial gradient and conductive electron energy spatial gradient or thermal gradient. • Unidirectional current stability is associated with asymmetric nanodomains along nanosize conductive paths. • Bidirectional current stability is inherent with either long conductive paths or nanosize conductive paths along symmetric nanodomains. • Conclusion: Surface design improves current stability across nanoelectonic junctions. - Abstract: A link between the morphological characteristics and the electric properties of amorphous layers is established by means of atomic, conductive, electrostatic force and thermal scanning microscopy. Using amorphous Ta{sub 2}O{sub 5} (a-Ta{sub 2}O{sub 5}) semiconductive layer, it is found that surface profile gradients (morphological gradient), are highly correlated to both the electron energy gradient of trapped electrons in interactive Coulombic sites and the thermal gradient along conductive paths and thus thermal and electric properties are correlated with surface morphology at the nanoscale. Furthermore, morphological and electron energy gradients along opposite conductive paths of electrons intrinsically impose a current stability anisotropy. For either long conductive paths (L > 1 μm) or along symmetric nanodomains, current stability for both positive and negative currents i is demonstrated. On the contrary, for short conductive paths along non-symmetric nanodomains, the set of independent variables (L, i) is spanned by two current stability/intability loci. One locus specifies a stable state for negative currents, while the other locus also describes a stable state for positive currents.

Voltage tunability of thermal conductivity in ferroelectric materials

Science.gov (United States)

Ihlefeld, Jon; Hopkins, Patrick Edward

2016-02-09

A method to control thermal energy transport uses mobile coherent interfaces in nanoscale ferroelectric films to scatter phonons. The thermal conductivity can be actively tuned, simply by applying an electrical potential across the ferroelectric material and thereby altering the density of these coherent boundaries to directly impact thermal transport at room temperature and above. The invention eliminates the necessity of using moving components or poor efficiency methods to control heat transfer, enabling a means of thermal energy control at the micro- and nano-scales.

Improved laser damage threshold performance of calcium fluoride optical surfaces via Accelerated Neutral Atom Beam (ANAB) processing

Science.gov (United States)

Kirkpatrick, S.; Walsh, M.; Svrluga, R.; Thomas, M.

2015-11-01

contaminants, nano-scale scratches, bumps, particles and other asperities under low energy physical sputtering conditions. ANAB may be used to remove a precisely controlled, uniform thickness of material without any increase of surface roughness, regardless of the total amount of material removed. The ANAB process does not involve the use of slurries or other abrasive polishing compounds and therefore does not require any post process cleaning. ANAB can be integrated as an in-situ surface preparation method for other process steps in the uninterrupted fabrication of optical devices.

Superhydrophobic surfaces by electrochemical processes.

Science.gov (United States)

Darmanin, Thierry; Taffin de Givenchy, Elisabeth; Amigoni, Sonia; Guittard, Frederic

2013-03-13

This review is an exhaustive representation of the electrochemical processes reported in the literature to produce superhydrophobic surfaces. Due to the intensive demand in the elaboration of superhydrophobic materials using low-cost, reproducible and fast methods, the use of strategies based on electrochemical processes have exponentially grown these last five years. These strategies are separated in two parts: the oxidation processes, such as oxidation of metals in solution, the anodization of metals or the electrodeposition of conducting polymers, and the reduction processed such as the electrodeposition of metals or the galvanic deposition. One of the main advantages of the electrochemical processes is the relative easiness to produce various surface morphologies and a precise control of the structures at a micro- or a nanoscale. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon Quantum Dot Surface-Engineered VO2 Interwoven Nanowires: A Flexible Cathode Material for Lithium and Sodium Ion Batteries.

Science.gov (United States)

Balogun, Muhammad-Sadeeq; Luo, Yang; Lyu, Feiyi; Wang, Fuxin; Yang, Hao; Li, Haibo; Liang, Chaolun; Huang, Miao; Huang, Yongchao; Tong, Yexiang

2016-04-20

The use of electrode materials in their powdery form requires binders and conductive additives for the fabrication of the cells, which leads to unsatisfactory energy storage performance. Recently, a new strategy to design flexible, binder-, and additive-free three-dimensional electrodes with nanoscale surface engineering has been exploited in boosting the storage performance of electrode materials. In this paper, we design a new type of free-standing carbon quantum dot coated VO2 interwoven nanowires through a simple fabrication process and demonstrate its potential to be used as cathode material for lithium and sodium ion batteries. The versatile carbon quantum dots that are vastly flexible for surface engineering serve the function of protecting the nanowire surface and play an important role in the diffusion of electrons. Also, the three-dimensional carbon cloth coated with VO2 interwoven nanowires assisted in the diffusion of ions through the inner and the outer surface. With this unique architecture, the carbon quantum dot nanosurface engineered VO2 electrode exhibited capacities of 420 and 328 mAh g(-1) at current density rate of 0.3 C for lithium and sodium storage, respectively. This work serves as a milestone for the potential replacement of lithium ion batteries and next generation postbatteries.

Nanoscale Topographical Characterization of Orbital Implant Materials

Directory of Open Access Journals (Sweden)

Marco Salerno

2018-04-01

Full Text Available The search for an ideal orbital implant is still ongoing in the field of ocular biomaterials. Major limitations of currently-available porous implants include the high cost along with a non-negligible risk of exposure and postoperative infection due to conjunctival abrasion. In the effort to develop better alternatives to the existing devices, two types of new glass-ceramic porous implants were fabricated by sponge replication, which is a relatively inexpensive method. Then, they were characterized by direct three-dimensional (3D contact probe mapping in real space by means of atomic force microscopy in order to assess their surface micro- and nano-features, which were quantitatively compared to those of the most commonly-used orbital implants. These silicate glass-ceramic materials exhibit a surface roughness in the range of a few hundred nanometers (Sq within 500–700 nm and topographical features comparable to those of clinically-used “gold-standard” alumina and polyethylene porous orbital implants. However, it was noted that both experimental and commercial non-porous implants were significantly smoother than all the porous ones. The results achieved in this work reveal that these porous glass-ceramic materials show promise for the intended application and encourage further investigation of their clinical suitability.

Tribo-functionalizing Si and SU8 materials by surface modification for application in MEMS/NEMS actuator-based devices

International Nuclear Information System (INIS)

Singh, R A; Satyanarayana, N; Sinha, S K; Kustandi, T S

2011-01-01

Micro/nano-electro-mechanical-systems (MEMS/NEMS) are miniaturized devices built at micro/nanoscales. At these scales, the surface/interfacial forces are extremely strong and they adversely affect the smooth operation and the useful operating lifetimes of such devices. When these forces manifest in severe forms, they lead to material removal and thereby reduce the wear durability of the devices. In this paper, we present a simple, yet robust, two-step surface modification method to significantly enhance the tribological performance of MEMS/NEMS materials. The two-step method involves oxygen plasma treatment of polymeric films and the application of a nanolubricant, namely perfluoropolyether. We apply the two-step method to the two most important MEMS/NEMS structural materials, namely silicon and SU8 polymer. On applying surface modification to these materials, their initial coefficient of friction reduces by ∼4-7 times and the steady-state coefficient of friction reduces by ∼2.5-3.5 times. Simultaneously, the wear durability of both the materials increases by >1000 times. The two-step method is time effective as each of the steps takes the time duration of approximately 1 min. It is also cost effective as the oxygen plasma treatment is a part of the MEMS/NEMS fabrication process. The two-step method can be readily and easily integrated into MEMS/NEMS fabrication processes. It is anticipated that this method will work for any kind of structural material from which MEMS/NEMS are or can be made.

Tribo-functionalizing Si and SU8 materials by surface modification for application in MEMS/NEMS actuator-based devices

Science.gov (United States)

Singh, R. A.; Satyanarayana, N.; Kustandi, T. S.; Sinha, S. K.

2011-01-01

Micro/nano-electro-mechanical-systems (MEMS/NEMS) are miniaturized devices built at micro/nanoscales. At these scales, the surface/interfacial forces are extremely strong and they adversely affect the smooth operation and the useful operating lifetimes of such devices. When these forces manifest in severe forms, they lead to material removal and thereby reduce the wear durability of the devices. In this paper, we present a simple, yet robust, two-step surface modification method to significantly enhance the tribological performance of MEMS/NEMS materials. The two-step method involves oxygen plasma treatment of polymeric films and the application of a nanolubricant, namely perfluoropolyether. We apply the two-step method to the two most important MEMS/NEMS structural materials, namely silicon and SU8 polymer. On applying surface modification to these materials, their initial coefficient of friction reduces by ~4-7 times and the steady-state coefficient of friction reduces by ~2.5-3.5 times. Simultaneously, the wear durability of both the materials increases by >1000 times. The two-step method is time effective as each of the steps takes the time duration of approximately 1 min. It is also cost effective as the oxygen plasma treatment is a part of the MEMS/NEMS fabrication process. The two-step method can be readily and easily integrated into MEMS/NEMS fabrication processes. It is anticipated that this method will work for any kind of structural material from which MEMS/NEMS are or can be made.

Nanoscale Metal Oxide Semiconductors for Gas Sensing

Science.gov (United States)

Hunter, Gary W.; Evans, Laura; Xu, Jennifer C.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.

2011-01-01

A report describes the fabrication and testing of nanoscale metal oxide semiconductors (MOSs) for gas and chemical sensing. This document examines the relationship between processing approaches and resulting sensor behavior. This is a core question related to a range of applications of nanotechnology and a number of different synthesis methods are discussed: thermal evaporation- condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed, providing a processing overview to developers of nanotechnology- based systems. The results of a significant amount of testing and comparison are also described. A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. The TECsynthesized single-crystal nanowires offer uniform crystal surfaces, resistance to sintering, and their synthesis may be done apart from the substrate. The TECproduced nanowire response is very low, even at the operating temperature of 200 C. In contrast, the electrospun polycrystalline nanofiber response is high, suggesting that junction potentials are superior to a continuous surface depletion layer as a transduction mechanism for chemisorption. Using a catalyst deposited upon the surface in the form of nanoparticles yields dramatic gains in sensitivity for both nanostructured, one-dimensional forms. For the nanowire materials, the response magnitude and response rate uniformly increase with increasing operating temperature. Such changes are interpreted in terms of accelerated surface diffusional processes, yielding greater access to chemisorbed oxygen species and faster dissociative chemisorption, respectively. Regardless of operating temperature, sensitivity of the nanofibers is a factor of 10 to 100 greater than that of nanowires with the same catalyst for the same test condition. In summary, nanostructure appears critical to governing the reactivity, as measured by electrical

Boiling performance and material robustness of modified surfaces with multi scale structures for fuel cladding development

Energy Technology Data Exchange (ETDEWEB)

Jo, HangJin; Kim, Jin Man [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784, Gyungbuk (Korea, Republic of); Yeom, Hwasung [Department of Nuclear Engineering and Engineering physics, UW-Madison, Madison, WI 53706, Unities States (United States); Lee, Gi Cheol [Department of Mechanical Engineering, POSTECH, Pohang 790-784, Gyungbuk (Korea, Republic of); Park, Hyun Sun, E-mail: hejsunny@postech.ac.kr [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784, Gyungbuk (Korea, Republic of); Kiyofumi, Moriyama; Kim, Moo Hwan [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784, Gyungbuk (Korea, Republic of); Sridharan, Kumar; Corradini, Michael [Department of Nuclear Engineering and Engineering physics, UW-Madison, Madison, WI 53706, Unities States (United States)

2015-09-15

Highlights: • We improved boiling performance and material robustness using surface modification. • We combined micro/millimeter post structures and nanoparticles with heat treatments. • Compactly-arranged micrometer posts had improved boiling performance. • CHF increased significantly due to capillary pumping by the deposited NP layers. • Sintering procedure increased mechanical strength of the NP coating surface. - Abstract: By regulating the geometrical characteristics of multi-scale structures and by adopting heat treatment for protective layer of nanoparticles (NPs), we improved critical heat flux (CHF), boiling heat transfer (BHT), and mechanical robustness of the modified surface. We fabricated 1-mm and 100-μm post structures and deposited NPs on the structured surface as a nano-scale structured layer and protective layer at the same time, then evaluated the CHF and BHT and material robustness of the modified surfaces. On the structured surfaces without NPs, the surface with compactly-arranged micrometer posts had improved CHF (118%) and BHT (41%). On the surface with structures on which NPs had been deposited, CHF increased significantly (172%) due to capillary pumping by the deposited NP layers. The heat treatment improved robustness of coating layer in comparison to the one of before heat treatment. In particular, low-temperature sintering increased the hardness of the modified surface by 140%. The increased mechanical strength of the NP coating is attributed to reduction in coating porosity during sintering. The combination of micrometer posts structures and sintered NP coating can increase the safety, efficiency and reliability of advanced nuclear fuel cladding.

Boiling performance and material robustness of modified surfaces with multi scale structures for fuel cladding development

International Nuclear Information System (INIS)

Jo, HangJin; Kim, Jin Man; Yeom, Hwasung; Lee, Gi Cheol; Park, Hyun Sun; Kiyofumi, Moriyama; Kim, Moo Hwan; Sridharan, Kumar; Corradini, Michael

2015-01-01

Highlights: • We improved boiling performance and material robustness using surface modification. • We combined micro/millimeter post structures and nanoparticles with heat treatments. • Compactly-arranged micrometer posts had improved boiling performance. • CHF increased significantly due to capillary pumping by the deposited NP layers. • Sintering procedure increased mechanical strength of the NP coating surface. - Abstract: By regulating the geometrical characteristics of multi-scale structures and by adopting heat treatment for protective layer of nanoparticles (NPs), we improved critical heat flux (CHF), boiling heat transfer (BHT), and mechanical robustness of the modified surface. We fabricated 1-mm and 100-μm post structures and deposited NPs on the structured surface as a nano-scale structured layer and protective layer at the same time, then evaluated the CHF and BHT and material robustness of the modified surfaces. On the structured surfaces without NPs, the surface with compactly-arranged micrometer posts had improved CHF (118%) and BHT (41%). On the surface with structures on which NPs had been deposited, CHF increased significantly (172%) due to capillary pumping by the deposited NP layers. The heat treatment improved robustness of coating layer in comparison to the one of before heat treatment. In particular, low-temperature sintering increased the hardness of the modified surface by 140%. The increased mechanical strength of the NP coating is attributed to reduction in coating porosity during sintering. The combination of micrometer posts structures and sintered NP coating can increase the safety, efficiency and reliability of advanced nuclear fuel cladding

Deep eutectic solvents: sustainable media for nanoscale and functional materials.

Science.gov (United States)

Wagle, Durgesh V; Zhao, Hua; Baker, Gary A

2014-08-19

Deep eutectic solvents (DESs) represent an alternative class of ionic fluids closely resembling room-temperature ionic liquids (RTILs), although, strictly speaking, they are distinguished by the fact that they also contain an organic molecular component (typically, a hydrogen bond donor like a urea, amide, acid, or polyol), frequently as the predominant constituent. Practically speaking, DESs are attractive alternatives to RTILs, sharing most of their remarkable qualities (e.g., tolerance to humidity, negligible vapor pressure, thermostability, wide electrochemical potential windows, tunability) while overcoming several limitations associated with their RTIL cousins. Particularly, DESs are typically, less expensive, more synthetically accessible (typically, from bulk commodity chemicals using solvent/waste-free processes), nontoxic, and biodegradable. In this Account, we provide an overview of DESs as designer solvents to create well-defined nanomaterials including shape-controlled nanoparticles, electrodeposited films, metal-organic frameworks, colloidal assemblies, hierarchically porous carbons, and DNA/RNA architectures. These breakthroughs illustrate how DESs can fulfill multiple roles in directing chemistry at the nanoscale: acting as supramolecular template, metal/carbon source, sacrificial agent (e.g., ammonia release from urea), and/or redox agent, all in the absence of formal stabilizing ligand (here, solvent and stabilizer are one and the same). The ability to tailor the physicochemical properties of DESs is central to controlling their interfacial behavior. The preorganized "supramolecular" nature of DESs provides a soft template to guide the formation of bimodal porous carbon networks or the evolution of electrodeposits. A number of essential parameters (viscosity, polarity, surface tension, hydrogen bonding), plus coordination with solutes/surfaces, all play significant roles in modulating species reactivity and mass transport properties governing the

Nitrogen and oxygen co-doped carbon nanofibers with rich sub-nanoscale pores as self-supported electrode material of high-performance supercapacitors

International Nuclear Information System (INIS)

Li, Qun; Xie, Wenhe; Liu, Dequan; Wang, Qi; He, Deyan

2016-01-01

Self-supported porous carbon nanofibers (CNFs) network has been prepared by electrospinning technology assisted with template method. The as-prepared material is rich in sub-nanoscale pores and nitrogen and oxygen functional groups, which can serve as a fast conductive network with abundant electrochemical active sites and greatly facilitates the transport of electrons and ions. When the porous CNFs network is used as an electrode for supercapacitor in a three electrode system, it displays a high capacitance of 233.1 F/g at 0.2 A/g, and a capacitance of 130.2 F/g even at 14 A/g. It maintains a capacitance of 154.0 F/g with 90.17% retention after 4000 cycles at 2 A/g. Moreover, the assembled symmetric supercapacitor not only exhibits excellent rate capability and cycle performance, but also delivers an energy density of 4.17 Wh/kg and a power density of 2500 W/kg. The experimental results demonstrate that the prepared N, O co-doped carbon nanofibers with rich sub-nanoscale pores are a promising electrode material for high-performance supercapacitors.

A Study of the Surface Structure of Polymorphic Graphene and Other Two-Dimensional Materials for Use in Novel Electronics and Organic Photovoltaics

Science.gov (United States)

Grady, Maxwell

For some time there has been interest in the fundamental physical properties of low- dimensional material systems. The discovery of graphene as a stable two-dimensional form of solid carbon lead to an exponential increase in research in two-dimensional and other re- duced dimensional systems. It is now known that there is a wide range of materials which are stable in two-dimensional form. These materials span a large configuration space of struc- tural, mechanical, and electronic properties, which results in the potential to create novel electronic devices from nano-scale heterostructures with exactly tailored device properties. Understanding the material properties at the nanoscale level requires specialized tools to probe materials with atomic precision. Here I present the growth and analysis of a novel graphene-ruthenium system which exhibits unique polymorphism in its surface structure, hereby referred to as polymorphic graphene. Scanning Tunneling Microscopy (STM) investigations of the polymorphic graphene surface reveal a periodically rippled structure with a vast array of domains, each exhibiting xvia unique moire period. The majority of moire domains found in this polymorphic graphene system are previously unreported in past studies of the structure of graphene on ruthenium. To better understand many of the structural properties of this system, characterization methods beyond those available at the UNH surface science lab are employed. Further investigation using Low Energy Electron Microscopy (LEEM) has been carried out at Sandia National Laboratory's Center for Integrated Nanotechnology and the Brookhaven National Laboratory Center for Functional Nanomaterials. To aid in analysis of the LEEM data, I have developed an open source software package to automate extraction of electron reflectivity curves from real space and reciprocal space data sets. This software has been used in the study of numerous other two-dimensional materials beyond graphene. When

Chitosan capped nanoscale Fe-MIL-88B-NH2 metal-organic framework as drug carrier material for the pH responsive delivery of doxorubicin

Science.gov (United States)

Sivakumar, P.; Priyatharshni, S.; Nagashanmugam, K. B.; Thanigaivelan, A.; Kumar, K.

2017-08-01

In recent years nanoscale metal-organic frameworks (NMOFs) are contributing as an effective material for use in drug delivery and imaging applications due to their porous surfaces and easy surface modifications. In this work, Fe-MIL-88B-NH2 NMOFs were successfully synthesized on facile hydrothermal route and 2-aminoterephthalic acid (NH2-BDC) was employed as a bridging ligand to activate amine functional groups on the surface. Amine functional groups not only serve as a structure stabilizing agent but also enhance the loading efficiency of the doxorubicin (DOX) anticancer drug. A pH responsive DOX release was realized by introducing a positively charged chitosan (Chi) capping layer. Upon Chi-coating, cleavage was observed in the Fe-MIL-88B-NH2 structure at acidic pH, while gel-like insoluble structure was formed at basic pH. By utilizing this phenomenon, a pH responsive DOX release system was developed by using Chi capped Fe-MIL-88B-NH2 NMOFs under the designed pH (4.0-8.0). The results suggest the Chi capped Fe-MIL-88B-NH2 can be a promising candidate for future pH responsive drug delivery systems.

Real time macrophage migration analysis and associated pro-inflammatory cytokine release on transparent carbon nanotube/polymer composite nano-film

International Nuclear Information System (INIS)

Khang, Dongwoo

2015-01-01

Surface chemistry and nanoscale surface morphology are both influential factors for cell adhesion, growth, and differentiation. In particular, cell migration is one of the major markers of initial immune response activation to implanted biomaterials. Despite their indication, it has been difficult to directly examine macrophages on nanoscale materials, because most nanomaterials possess greater thicknesses than nanoscale. This study developed transparent films comprising a carbon nanotube and polymer composite with controlled surface stiffness and nanoscale roughness. As nanoscale surface topography can incite immune cell activation, analysis of the real-time cell migration (including velocity) of macrophages due to changes in nanoscale surface topography of a biopolymer can support the direct relationship between initial macrophage dynamics and corresponding pro-inflammatory responses. Through real-time analysis, we have identified that surface chemistry and surface nanoscale topography are both independent factors mediating macrophage interactions, and, thus, immune cell behavior can be further controlled by the systematic variation of nanoscale surface topography for a given surface chemistry. Considering that the initial immune response can determine the fate and lifetime of implanted biomaterials, this study presents the direct relationship between initial macrophage dynamics and subsequent inflammatory cytokine release on transparent carbon nanotube polymer composites. (paper)

Tailoring the nanoscale morphology of HKUST-1 thin films via codeposition and seeded growth.

Science.gov (United States)

Brower, Landon J; Gentry, Lauren K; Napier, Amanda L; Anderson, Mary E

2017-01-01

Integration of surface-anchored metal-organic frameworks (surMOFs) within hierarchical architectures is necessary for potential sensing, electronic, optical, or separation applications. It is important to understand the fundamentals of film formation for these surMOFs in order to develop strategies for their incorporation with nanoscale control over lateral and vertical dimensions. This research identified processing parameters to control the film morphology for surMOFs of HKUST-1 fabricated by codeposition and seeded deposition. Time and temperature were investigated to observe film formation, to control film thickness, and to tune morphology. Film thickness was investigated by ellipsometry, while film structure and film roughness were characterized by atomic force microscopy. Films formed via codeposition resulted in nanocrystallites anchored to the gold substrate. A dynamic process at the interface was observed with a low density of large particulates (above 100 nm) initially forming on the substrate; and over time these particulates were slowly replaced by the prevalence of smaller crystallites (ca. 10 nm) covering the substrate at a high density. Elevated temperature was found to expedite the growth process to obtain the full range of surface morphologies with reasonable processing times. Seed crystals formed by the codeposition method were stable and nucleated growth throughout a subsequent layer-by-layer deposition process. These seed crystals templated the final film structure and tailor the features in lateral and vertical directions. Using codeposition and seeded growth, different surface morphologies with controllable nanoscale dimensions can be designed and fabricated for integration of MOF systems directly into device architectures and sensor platforms.

Tailoring the nanoscale morphology of HKUST-1 thin films via codeposition and seeded growth

Directory of Open Access Journals (Sweden)

Landon J. Brower

2017-11-01

Full Text Available Integration of surface-anchored metal-organic frameworks (surMOFs within hierarchical architectures is necessary for potential sensing, electronic, optical, or separation applications. It is important to understand the fundamentals of film formation for these surMOFs in order to develop strategies for their incorporation with nanoscale control over lateral and vertical dimensions. This research identified processing parameters to control the film morphology for surMOFs of HKUST-1 fabricated by codeposition and seeded deposition. Time and temperature were investigated to observe film formation, to control film thickness, and to tune morphology. Film thickness was investigated by ellipsometry, while film structure and film roughness were characterized by atomic force microscopy. Films formed via codeposition resulted in nanocrystallites anchored to the gold substrate. A dynamic process at the interface was observed with a low density of large particulates (above 100 nm initially forming on the substrate; and over time these particulates were slowly replaced by the prevalence of smaller crystallites (ca. 10 nm covering the substrate at a high density. Elevated temperature was found to expedite the growth process to obtain the full range of surface morphologies with reasonable processing times. Seed crystals formed by the codeposition method were stable and nucleated growth throughout a subsequent layer-by-layer deposition process. These seed crystals templated the final film structure and tailor the features in lateral and vertical directions. Using codeposition and seeded growth, different surface morphologies with controllable nanoscale dimensions can be designed and fabricated for integration of MOF systems directly into device architectures and sensor platforms.

Surface and Interface Physics of Correlated Electron Materials

Energy Technology Data Exchange (ETDEWEB)

Millis, Andrew [Columbia Univ., New York, NY (United States)

2004-09-01

The {\\it Surface and Interface Physics of Correlated Electron Materials} research program provided conceptual understanding of and theoretical methodologies for understanding the properties of surfaces and interfaces involving materials exhibiting strong electronic correlations. The issues addressed in this research program are important for basic science, because the behavior of correlated electron superlattices is a crucial challenge to and crucial test of our understanding of the grand-challenge problem of correlated electron physics and are important for our nation's energy future because correlated interfaces offer opportunities for the control of phenomena needed for energy and device applications. Results include new physics insights, development of new methods, and new predictions for materials properties.

Polymer microfilters with nanostructured surfaces for the culture of circulating cancer cells

International Nuclear Information System (INIS)

Makarova, Olga V.; Adams, Daniel L.; Divan, Ralu; Rosenmann, Daniel; Zhu, Peixuan; Li, Shuhong; Amstutz, Platte; Tang, Cha-Mei

2016-01-01

There is a critical need to improve the accuracy of drug screening and testing through the development of in vitro culture systems that more effectively mimic the in vivo environment. Surface topographical features on the nanoscale level, in short nanotopography, effect the cell growth patterns, and hence affect cell function in culture. We report the preliminary results on the fabrication, and subsequent cellular growth, of nanoscale surface topography on polymer microfilters using cell lines as a precursor to circulating tumor cells (CTCs). To create various nanoscale features on the microfilter surface, we used reactive ion etching (RIE) with and without an etching mask. An anodized aluminum oxide (AAO) membrane fabricated directly on the polymer surface served as an etching mask. Polymer filters with a variety of modified surfaces were used to compare the effects on the culture of cancer cell lines in blank culture wells, with untreated microfilters or with RIE-treated microfilters. We then report the differences of cell shape, phenotype and growth patterns of bladder and glioblastoma cancer cell lines after isolation on the various types of material modifications. Our data suggest that RIE modified polymer filters can isolate model cell lines while retaining ell viability, and that the RIE filter modification allows T24 monolayering cells to proliferate as a structured cluster. - Highlights: • Surface topographical effects the growth patterns and cell function of cancer cells • Nanoscale surface topography on polymer filters for circulating tumor cell culture • Membrane fabricated directly on polymer surfaces utilized for polymer etching • Nanotopography alters cell shape, phenotype and growth patterns of cancer cells • Nanoscale surface topography dictates monolayering or 3D structured cell culture

Polymer microfilters with nanostructured surfaces for the culture of circulating cancer cells

Energy Technology Data Exchange (ETDEWEB)

Makarova, Olga V. [Creatv MicroTech, Inc., 2242 West Harrison St., Chicago 60612, IL (United States); Adams, Daniel L., E-mail: dan@creatvmicrotech.com [Creatv MicroTech, Inc., 1 Deer Park Drive, Monmouth Junction, NJ 08852 (United States); Divan, Ralu; Rosenmann, Daniel [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Ave., Argonne 60439, IL (United States); Zhu, Peixuan; Li, Shuhong; Amstutz, Platte; Tang, Cha-Mei [Creatv MicroTech, Inc., 11609 Lake Potomac Drive, Potomac 20854, MD (United States)

2016-09-01

There is a critical need to improve the accuracy of drug screening and testing through the development of in vitro culture systems that more effectively mimic the in vivo environment. Surface topographical features on the nanoscale level, in short nanotopography, effect the cell growth patterns, and hence affect cell function in culture. We report the preliminary results on the fabrication, and subsequent cellular growth, of nanoscale surface topography on polymer microfilters using cell lines as a precursor to circulating tumor cells (CTCs). To create various nanoscale features on the microfilter surface, we used reactive ion etching (RIE) with and without an etching mask. An anodized aluminum oxide (AAO) membrane fabricated directly on the polymer surface served as an etching mask. Polymer filters with a variety of modified surfaces were used to compare the effects on the culture of cancer cell lines in blank culture wells, with untreated microfilters or with RIE-treated microfilters. We then report the differences of cell shape, phenotype and growth patterns of bladder and glioblastoma cancer cell lines after isolation on the various types of material modifications. Our data suggest that RIE modified polymer filters can isolate model cell lines while retaining ell viability, and that the RIE filter modification allows T24 monolayering cells to proliferate as a structured cluster. - Highlights: • Surface topographical effects the growth patterns and cell function of cancer cells • Nanoscale surface topography on polymer filters for circulating tumor cell culture • Membrane fabricated directly on polymer surfaces utilized for polymer etching • Nanotopography alters cell shape, phenotype and growth patterns of cancer cells • Nanoscale surface topography dictates monolayering or 3D structured cell culture.

Is there an optimal topographical surface in nano-scale affecting protein adsorption and cell behaviors? Part II

Energy Technology Data Exchange (ETDEWEB)

Wang Huajie, E-mail: wanghuajie972001@163.com; Sun Yuanyuan; Cao Ying, E-mail: caoying1130@sina.com; Wang Kui; Yang Lin [Henan Normal University, College of Chemistry and Environmental Science (China); Zhang Yidong; Zheng Zhi [Xuchang University, Institute of Surface Micro and Nano Materials (China)

2012-05-15

Although nano-structured surfaces exhibit superior biological activities to the smooth or micro-structured surfaces, whether there is an optimal topographical surface in nano-scale affecting protein adsorption and cell behaviors is still controversial. In this study, porous aluminum oxide membranes with different pore sizes ranging from 25 to 120 nm were prepared by the anodic oxidation technique. The surface morphology, topography and wettability were analyzed by scanning electron microscope, atomic force microscope and water contact angle measurement, respectively. The results indicated that the synergistic action of the nano-topography structure and hydrophilic/hydrophobic properties resulted in a highest protein adsorption on the aluminum oxide membrane with 80 nm pore size. Additionally, the morphological, metabolic and cell counting methods showed that cells had different sensitivity to porous aluminum oxide membranes with different surface features. Furthermore, this sensitivity was cell type dependent. The optimal pore size of aluminum oxide membranes for cell growth was 80 nm for PC12 cells and 50 nm for NIH 3T3 cells.

Surface Treatment of Polymeric Materials Controlling the Adhesion of Biomolecules

Directory of Open Access Journals (Sweden)

Willy Zorzi

2012-08-01

Full Text Available This review describes different strategies of surface elaboration for a better control of biomolecule adsorption. After a brief description of the fundamental interactions between surfaces and biomolecules, various routes of surface elaboration are presented dealing with the attachment of functional groups mostly thanks to plasma techniques, with the grafting to and from methods, and with the adsorption of surfactants. The grafting of stimuli-responsive polymers is also pointed out. Then, the discussion is focused on the protein adsorption phenomena showing how their interactions with solid surfaces are complex. The adsorption mechanism is proved to be dependent on the solid surface physicochemical properties as well as on the surface and conformation properties of the proteins. Different behaviors are also reported for complex multiple protein solutions.

Surface Treatment of Polymeric Materials Controlling the Adhesion of Biomolecules

Science.gov (United States)

Poncin-Epaillard, Fabienne; Vrlinic, Tjasa; Debarnot, Dominique; Mozetic, Miran; Coudreuse, Arnaud; Legeay, Gilbert; El Moualij, Benaïssa; Zorzi, Willy

2012-01-01

This review describes different strategies of surface elaboration for a better control of biomolecule adsorption. After a brief description of the fundamental interactions between surfaces and biomolecules, various routes of surface elaboration are presented dealing with the attachment of functional groups mostly thanks to plasma techniques, with the grafting to and from methods, and with the adsorption of surfactants. The grafting of stimuli-responsive polymers is also pointed out. Then, the discussion is focused on the protein adsorption phenomena showing how their interactions with solid surfaces are complex. The adsorption mechanism is proved to be dependent on the solid surface physicochemical properties as well as on the surface and conformation properties of the proteins. Different behaviors are also reported for complex multiple protein solutions. PMID:24955631

Understanding and exploiting nanoscale surface heterogeneity for particle and cell manipulation

Science.gov (United States)

Kalasin, Surachate

This thesis explores the impact of surface heterogeneities on colloidal interactions and translates concepts to biointerfacial systems, for instance, microfluidic and biomedical devices. The thesis advances a model system, originally put forth by Kozlova: Tunable electrostatic surface heterogeneity is produced by adsorbing small amounts of cationic polyelectrolyte on a silica flat. The resulting positive electrostatic patches possess a density that is tuned from a saturated carpet down to average spacings on the order of a few hundred nanometers. At these length-scales, multiple adhesive elements (from tens to thousands) are present in the area of contact between a particle and a surface, a distinguishing feature of the thesis. Much of the literature addressing surface "heterogeneity" engineers surfaces with micron-scale features, almost always larger than the contact area between a particle and a second surface. With a nanoscale heterogeneity model, this thesis reports and quantitatively explains particle interaction behavior not typical of homogeneous interfaces. This includes (1) an adhesion threshold, a minimum average surface density of cationic patches needed for particle capture, (previously observed by Kozlova); (2) a crossover, from salt-destabilized to salt-stabilized interactions between heterogeneous surfaces with net-negative charge; (3) a shift of the adhesion threshold with shear, reducing adhesion; (4) a crossover from shear-enhanced to shear-hindered particle adhesion; (5) a range of surface compositions and processing parameters that sustain particle rolling; and (6) conditions where particles arrest immediately on contact. Through variations in ionic strength and particle size, the particle-surface contact area is systematically varied relative to the heterogeneity lengthscale. This provides a semi-quantitative explanation for the shifting of the adhesion threshold, in terms of the statistical probability of a particle being able to find a

Carbon Nanotube Templated Microfabrication of Porous Silicon-Carbon Materials

Science.gov (United States)

Song, Jun; Jensen, David; Dadson, Andrew; Vail, Michael; Linford, Matthew; Vanfleet, Richard; Davis, Robert

2010-10-01

Carbon nanotube templated microfabrication (CNT-M) of porous materials is demonstrated. Partial chemical infiltration of three dimensional carbon nanotube structures with silicon resulted in a mechanically robust material, precisely structured from the 10 nm scale to the 100 micron scale. Nanoscale dimensions are determined by the diameter and spacing of the resulting silicon/carbon nanotubes while the microscale dimensions are controlled by lithographic patterning of the CNT growth catalyst. We demonstrate the utility of this hierarchical structuring approach by using CNT-M to fabricate thin layer chromatography (TLC) separations media with precise microscale channels for fluid flow control and nanoscale porosity for high analyte capacity.

Active material, optical mode and cavity impact on nanoscale electro-optic modulation performance

Science.gov (United States)

Amin, Rubab; Suer, Can; Ma, Zhizhen; Sarpkaya, Ibrahim; Khurgin, Jacob B.; Agarwal, Ritesh; Sorger, Volker J.

2017-10-01

Electro-optic modulation is a key function in optical data communication and possible future optical compute engines. The performance of modulators intricately depends on the interaction between the actively modulated material and the propagating waveguide mode. While a variety of high-performance modulators have been demonstrated, no comprehensive picture of what factors are most responsible for high performance has emerged so far. Here we report the first systematic and comprehensive analytical and computational investigation for high-performance compact on-chip electro-optic modulators by considering emerging active materials, model considerations and cavity feedback at the nanoscale. We discover that the delicate interplay between the material characteristics and the optical mode properties plays a key role in defining the modulator performance. Based on physical tradeoffs between index modulation, loss, optical confinement factors and slow-light effects, we find that there exist combinations of bias, material and optical mode that yield efficient phase or amplitude modulation with acceptable insertion loss. Furthermore, we show how material properties in the epsilon near zero regime enable reduction of length by as much as by 15 times. Lastly, we introduce and apply a cavity-based electro-optic modulator figure of merit, Δλ/Δα, relating obtainable resonance tuning via phase shifting relative to the incurred losses due to the fundamental Kramers-Kronig relations suggesting optimized device operating regions with optimized modulation-to-loss tradeoffs. This work paves the way for a holistic design rule of electro-optic modulators for high-density on-chip integration.

III-V nanoelectronics and related surface/interface issues

International Nuclear Information System (INIS)

Hasegawa, Hideki

2003-01-01

The conventional logic gate architecture is not suitable for high-density integration of quantum devices which are non-robust and extremely structure- and charge-sensitive. In this paper, our novel hexagonal binary-decision-diagram (BDD) quantum circuit approach for III-V nanoelectronics is reviewed and related critical surface/interface issues for high-density integration are discussed. First, the basic concept and actual implementation method of our approach are explained, giving examples of novel BDD quantum integrated circuits where nanowire networks are controlled by nanoscale Schottky wrap gates. For high-density integration, growth of embedded sub-10 nm III-V quantum wire networks by selective molecular beam epitaxy (MBE) on patterned substrates is described, including effects of atomic hydrogen irradiation and kinetic control of wire width. The key processing issue lies in understanding and control of nanostructure surfaces/interfaces. Behavior of nanoscale Schottky gates, recent scanning tunneling microscopy (STM)/scanning tunneling spectroscopy (STS) studies of surface states, and successful removal of surface states by MBE-grown silicon interface control layer are discussed

A poly(vinyl alcohol)/sodium alginate blend monolith with nanoscale porous structure.

Science.gov (United States)

Sun, Xiaoxia; Uyama, Hiroshi

2013-10-04

A stimuli-responsive poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend monolith with nanoscale porous (mesoporous) structure is successfully fabricated by thermally impacted non-solvent induced phase separation (TINIPS) method. The PVA/SA blend monolith with different SA contents is conveniently fabricated in an aqueous methanol without any templates. The solvent suitable for the fabrication of the present blend monolith by TINIPS is different with that of the PVA monolith. The nanostructural control of the blend monolith is readily achieved by optimizing the fabrication conditions. Brunauer Emmett Teller measurement shows that the obtained blend monolith has a large surface area. Pore size distribution plot for the blend monolith obtained by the non-local density functional theory method reveals the existence of the nanoscale porous structure. Fourier transform infrared analysis reveals the strong interactions between PVA and SA. The pH-responsive property of the blend monolith is investigated on the basis of swelling ratio in different pH solutions. The present blend monolith of biocompatible and biodegradable PVA and SA with nanoscale porous structure has large potential for applications in biomedical and environmental fields.

In situ nanoscale refinement by highly controllable etching of the (111) silicon crystal plane and its influence on the enhanced electrical property of a silicon nanowire

International Nuclear Information System (INIS)

Gong Yibin; Dai Pengfei; Gao Anran; Li Tie; Zhou Ping; Wang Yuelin

2011-01-01

Nanoscale refinement on a (100) oriented silicon-on-insulator (SOI) wafer was introduced by using tetra-methyl-ammonium hydroxide (TMAH, 25 wt%) anisotropic silicon etchant, with temperature kept at 50 °C to achieve precise etching of the (111) crystal plane. Specifically for a silicon nanowire (SiNW) with oxide sidewall protection, the in situ TMAH process enabled effective size reduction in both lateral (2.3 nm/min) and vertical (1.7 nm/min) dimensions. A sub-50 nm SiNW with a length of microns with uniform triangular cross-section was achieved accordingly, yielding enhanced field effect transistor (FET) characteristics in comparison with its 100 nm-wide pre-refining counterpart, which demonstrated the feasibility of this highly controllable refinement process. Detailed examination revealed that the high surface quality of the (111) plane, as well as the bulk depletion property should be the causes of this electrical enhancement, which implies the great potential of the as-made cost-effective SiNW FET device in many fields. (semiconductor materials)

Nanoscale visualization of redox activity at lithium-ion battery cathodes.

Science.gov (United States)

Takahashi, Yasufumi; Kumatani, Akichika; Munakata, Hirokazu; Inomata, Hirotaka; Ito, Komachi; Ino, Kosuke; Shiku, Hitoshi; Unwin, Patrick R; Korchev, Yuri E; Kanamura, Kiyoshi; Matsue, Tomokazu

2014-11-17

Intercalation and deintercalation of lithium ions at electrode surfaces are central to the operation of lithium-ion batteries. Yet, on the most important composite cathode surfaces, this is a rather complex process involving spatially heterogeneous reactions that have proved difficult to resolve with existing techniques. Here we report a scanning electrochemical cell microscope based approach to define a mobile electrochemical cell that is used to quantitatively visualize electrochemical phenomena at the battery cathode material LiFePO4, with resolution of ~100 nm. The technique measures electrode topography and different electrochemical properties simultaneously, and the information can be combined with complementary microscopic techniques to reveal new perspectives on structure and activity. These electrodes exhibit highly spatially heterogeneous electrochemistry at the nanoscale, both within secondary particles and at individual primary nanoparticles, which is highly dependent on the local structure and composition.

Interfibrillar stiffening of echinoderm mutable collagenous tissue demonstrated at the nanoscale.

Science.gov (United States)

Mo, Jingyi; Prévost, Sylvain F; Blowes, Liisa M; Egertová, Michaela; Terrill, Nicholas J; Wang, Wen; Elphick, Maurice R; Gupta, Himadri S

2016-10-18

The mutable collagenous tissue (MCT) of echinoderms (e.g., sea cucumbers and starfish) is a remarkable example of a biological material that has the unique attribute, among collagenous tissues, of being able to rapidly change its stiffness and extensibility under neural control. However, the mechanisms of MCT have not been characterized at the nanoscale. Using synchrotron small-angle X-ray diffraction to probe time-dependent changes in fibrillar structure during in situ tensile testing of sea cucumber dermis, we investigate the ultrastructural mechanics of MCT by measuring fibril strain at different chemically induced mechanical states. By measuring a variable interfibrillar stiffness (E IF ), the mechanism of mutability at the nanoscale can be demonstrated directly. A model of stiffness modulation via enhanced fibrillar recruitment is developed to explain the biophysical mechanisms of MCT. Understanding the mechanisms of MCT quantitatively may have applications in development of new types of mechanically tunable biomaterials.

Simple Methods for Production of Nanoscale Metal Oxide Films from Household Sources

Science.gov (United States)

Campbell, Dean J.; Baliss, Michelle S.; Hinman, Jordan J.; Ziegenhorn, John W.; Andrews, Mark J.; Stevenson, Keith J.

2013-01-01

Production of thin metal oxide films was recently explored as part of an outreach program with a goal of producing nanoscale structures with household items. Household items coated with various metals or titanium compounds can be heated to produce colorful films with nanoscale thicknesses. As part of a materials chemistry laboratory experiment…

The creation of nanoscale structures on copper surfaces

International Nuclear Information System (INIS)

Parker, T.M.

1997-11-01

Epitaxial growth of metals onto the Cu(100) surface is shown to be controlled by the presence of c(2x2)N islands. At sub-saturation coverages the nitrogen islands have a very uniform size and shape. Deposition of metals such as Cu and Co onto the Cu(100)-c(2x2)N system results in epitaxial growth only on areas of the substrate left clean by the nitrogen islands. The nitrogen islands therefore act as a template to the epitaxially grown metal. The nature of the Cu(100)-c(2x2)N template is discussed in terms of the different preparation conditions. Two key factors are identified; the nitrogen coverage on the surface and the amount of annealing the surface receives after nitrogen dosing. A possible theoretical explanation for the unique properties of the Cu(100)-c(2x2)N system is also discussed. It is shown that the size and shape of epitaxially grown Cu and Co islands on the Cu(100)-c(2x2)N system are controlled by the template. Growth is controlled through a number of monolayers. As the amount of nitrogen on the surface is varied so the size and shape distributions of the epitaxially grown metal is changed. Finally, it is shown that sub-saturation coverages of oxygen on the Cu(110) surface also alters the growth mode of epitaxially grown Co. The island morphology is different depending on whether the island nucleates on the bare substrate or on an oxygen island. (author)

Nanoscale Ionic Materials

KAUST Repository

Rodriguez, Robert; Herrera, Rafael; Archer, Lynden A.; Giannelis, Emmanuel P.

2008-01-01

Polymer nanocomposites (nanoparticles dispersed in a polymer matrix) have been the subject of intense research for almost two decades in both academic and industrial settings. This interest has been fueled by the ability of nanocomposites to not only improve the performance of polymers, but also by their ability to introduce new properties. Yet, there are still challenges that polymer nanocomposites must overcome to reach their full potential. In this Research News article we discuss a new class of hybrids termed nanoparticle ionic materials (NIMS). NIMS are organic-inorganic hybrid materials comprising a nanoparticle core functionalized with a covalently tethered ionic corona. They are facilely engineered to display flow properties that span the range from glassy solids to free flowing liquids. These new systems have unique properties that can overcome some of the challenges facing nanocomosite materials. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.

Nanoscale Ionic Materials

KAUST Repository

Rodriguez, Robert

2008-11-18

Polymer nanocomposites (nanoparticles dispersed in a polymer matrix) have been the subject of intense research for almost two decades in both academic and industrial settings. This interest has been fueled by the ability of nanocomposites to not only improve the performance of polymers, but also by their ability to introduce new properties. Yet, there are still challenges that polymer nanocomposites must overcome to reach their full potential. In this Research News article we discuss a new class of hybrids termed nanoparticle ionic materials (NIMS). NIMS are organic-inorganic hybrid materials comprising a nanoparticle core functionalized with a covalently tethered ionic corona. They are facilely engineered to display flow properties that span the range from glassy solids to free flowing liquids. These new systems have unique properties that can overcome some of the challenges facing nanocomosite materials. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.

Nanoscale mechanical surface properties of single crystalline martensitic Ni-Mn-Ga ferromagnetic shape memory alloys

International Nuclear Information System (INIS)

Jakob, A M; Müller, M; Rauschenbach, B; Mayr, S G

2012-01-01

Located beyond the resolution limit of nanoindentation, contact resonance atomic force microscopy (CR-AFM) is employed for nano-mechanical surface characterization of single crystalline 14M modulated martensitic Ni-Mn-Ga (NMG) thin films grown by magnetron sputter deposition on (001) MgO substrates. Comparing experimental indentation moduli-obtained with CR-AFM-with theoretical predictions based on density functional theory (DFT) indicates the central role of pseudo plasticity and inter-martensitic phase transitions. Spatially highly resolved mechanical imaging enables the visualization of twin boundaries and allows for the assessment of their impact on mechanical behavior at the nanoscale. The CR-AFM technique is also briefly reviewed. Its advantages and drawbacks are carefully addressed. (paper)

Opto-nanomechanical spectroscopic material characterization

Science.gov (United States)

Tetard, L.; Passian, A.; Farahi, R. H.; Thundat, T.; Davison, B. H.

2015-10-01

The non-destructive, simultaneous chemical and physical characterization of materials at the nanoscale is an essential and highly sought-after capability. However, a combination of limitations imposed by Abbe diffraction, diffuse scattering, unknown subsurface, electromagnetic fluctuations and Brownian noise, for example, have made achieving this goal challenging. Here, we report a hybrid approach for nanoscale material characterization based on generalized nanomechanical force microscopy in conjunction with infrared photoacoustic spectroscopy. As an application, we tackle the outstanding problem of spatially and spectrally resolving plant cell walls. Nanoscale characterization of plant cell walls and the effect of complex phenotype treatments on biomass are challenging but necessary in the search for sustainable and renewable bioenergy. We present results that reveal both the morphological and compositional substructures of the cell walls. The measured biomolecular traits are in agreement with the lower-resolution chemical maps obtained with infrared and confocal Raman micro-spectroscopies of the same samples. These results should prove relevant in other fields such as cancer research, nanotoxicity, and energy storage and production, where morphological, chemical and subsurface studies of nanocomposites, nanoparticle uptake by cells and nanoscale quality control are in demand.

Nanoscale Organic Hybrid Electrolytes

KAUST Repository

Nugent, Jennifer L.

2010-08-20

Nanoscale organic hybrid electrolytes are composed of organic-inorganic hybrid nanostructures, each with a metal oxide or metallic nanoparticle core densely grafted with an ion-conducting polyethylene glycol corona - doped with lithium salt. These materials form novel solvent-free hybrid electrolytes that are particle-rich, soft glasses at room temperature; yet manifest high ionic conductivity and good electrochemical stability above 5V. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoscale Organic Hybrid Electrolytes

KAUST Repository

Nugent, Jennifer L.; Moganty, Surya S.; Archer, Lynden A.

2010-01-01

Nanoscale organic hybrid electrolytes are composed of organic-inorganic hybrid nanostructures, each with a metal oxide or metallic nanoparticle core densely grafted with an ion-conducting polyethylene glycol corona - doped with lithium salt. These materials form novel solvent-free hybrid electrolytes that are particle-rich, soft glasses at room temperature; yet manifest high ionic conductivity and good electrochemical stability above 5V. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Charge separation at nanoscale interfaces: energy-level alignment including two-quasiparticle interactions.

Science.gov (United States)

Li, Huashan; Lin, Zhibin; Lusk, Mark T; Wu, Zhigang

2014-10-21

The universal and fundamental criteria for charge separation at interfaces involving nanoscale materials are investigated. In addition to the single-quasiparticle excitation, all the two-quasiparticle effects including exciton binding, Coulomb stabilization, and exciton transfer are considered, which play critical roles on nanoscale interfaces for optoelectronic applications. We propose a scheme allowing adding these two-quasiparticle interactions on top of the single-quasiparticle energy level alignment for determining and illuminating charge separation at nanoscale interfaces. Employing the many-body perturbation theory based on Green's functions, we quantitatively demonstrate that neglecting or simplifying these crucial two-quasiparticle interactions using less accurate methods is likely to predict qualitatively incorrect charge separation behaviors at nanoscale interfaces where quantum confinement dominates.

The tritium confinement and surface chemistry of plasma facing materials in controlled D-T fusion devices

International Nuclear Information System (INIS)

Wu, C.H.

1987-01-01

Tritium permeation through first walls, limiters or divertors subjected to energetic tritium charge exchange neutral bombardment is a potentially serious problem area for advanced D-T reactors operating at elevated temperatures. High concentrations of tritium in the near surface region can be reached by implantation of the charge neutral flux combined with a relatively slow recombination of these atoms into molecules at the plasma/ first wall interface. A concentration gradient is established, causing tritium to diffuse into the bulk and essentially to the outer wall surface where it can enter the first wall coolant. Since tritium separation from cooling water is very costly, release of even a small fraction of tritium to the environment could pose undesirable safety problems. Therefore, it is necessary to reduce the tritium permeation. An analysis of the way of inhibition has been made. The tritium interacts with the solid surface of the plasma facing components, resulting in trapping and material erosion, and posing problems with respect to plasma density control. The erosion of the plasma facing component materials is mainly caused by physical and chemical erosion. A detailed analysis of chemical erosion by tritium has been performed and the results are described. (author)

Surface-Enhanced Raman Spectroscopy as a Probe of the Surface Chemistry of Nanostructured Materials.

Science.gov (United States)

Dick, Susan; Konrad, Magdalena P; Lee, Wendy W Y; McCabe, Hannah; McCracken, John N; Rahman, Taifur M D; Stewart, Alan; Xu, Yikai; Bell, Steven E J

2016-07-01

Surface-enhanced Raman spectroscopy (SERS) is now widely used as a rapid and inexpensive tool for chemical/biochemical analysis. The method can give enormous increases in the intensities of the Raman signals of low-concentration molecular targets if they are adsorbed on suitable enhancing substrates, which are typically composed of nanostructured Ag or Au. However, the features of SERS that allow it to be used as a chemical sensor also mean that it can be used as a powerful probe of the surface chemistry of any nanostructured material that can provide SERS enhancement. This is important because it is the surface chemistry that controls how these materials interact with their local environment and, in real applications, this interaction can be more important than more commonly measured properties such as morphology or plasmonic absorption. Here, the opportunity that this approach to SERS provides is illustrated with examples where the surface chemistry is both characterized and controlled in order to create functional nanomaterials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Note: Detector collimators for the nanoscale ordered materials diffractometer instrument at the Spallation Neutron Source

Energy Technology Data Exchange (ETDEWEB)

Tamalonis, A. [Materials Development, Inc., Arlington Heights, Illinois 60004 (United States); Weber, J. K. R., E-mail: rweber@anl.gov; Alderman, O. L. G. [Materials Development, Inc., Arlington Heights, Illinois 60004 (United States); Argonne National Laboratory, Argonne, Illinois 60439 (United States); Neuefeind, J. C.; Carruth, J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States); Skinner, L. B. [Materials Development, Inc., Arlington Heights, Illinois 60004 (United States); Argonne National Laboratory, Argonne, Illinois 60439 (United States); Stony Brook University, Stony Brook, New York 11794 (United States); Benmore, C. J. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2015-09-15

Five neutron collimator designs were constructed and tested at the nanoscale ordered materials diffractometer (NOMAD) instrument. Collimators were made from High Density PolyEthylene (HDPE) or 5% borated HDPE. In all cases, collimators improved the signal to background ratio and reduced detection of secondary scattering. In the Q-range 10-20 Å{sup −1}, signal to background ratio improved by factors of approximately 1.6 and 2.0 for 50 and 100 mm deep collimators, respectively. In the Q-range 40-50 Å{sup −1}, the improvement factors were 1.8 and 2.7. Secondary scattering as measured at Q ∼ 9.5 Å{sup −1} was significantly decreased when the collimators were installed.

Sharp Morphological Transitions from Nanoscale Mixed-Anchoring Patterns in Confined Nematic Liquid Crystals

Energy Technology Data Exchange (ETDEWEB)

Armas-Pérez, Julio C. [Institute; División; Li, Xiao [Institute; Martínez-González, José A. [Institute; Smith, Coleman [Institute; Hernández-Ortiz, J. P. [Departamento; Nealey, Paul F. [Institute; Materials; de Pablo, Juan J. [Institute; Materials

2017-08-17

Liquid crystals are known to be particularly sensitive to orientational cues provided at surfaces or interfaces. In this work, we explore theoretically, computationally, and experimentally the behavior of liquid crystals on isolated nanoscale patterns with controlled anchoring characteristics at small length scales. The orientation of the liquid crystal is controlled through the use of chemically patterned polymer brushes that are tethered to a surface. This system can be engineered with remarkable precision, and the central question addressed here is whether a characteristic length scale exists at which information encoded on a surface is no longer registered by a liquid crystal. To do so, we adopt a tensorial description of the free energy of the hybrid liquidcrystal surface system, and we investigate its morphology in a systematic manner. For long and narrow surface stripes, it is found that the liquid crystal follows the instructions provided by the pattern down to 100 nm widths. This is accomplished through the creation of line defects that travel along the sides of the stripes. We show that a "sharp" morphological transition occurs from a uniform undistorted alignment to a dual uniform/splay-bend morphology. The theoretical and numerical predictions advanced here are confirmed by experimental observations. Our combined analysis suggests that nanoscale patterns can be used to manipulate the orientation of liquid crystals at a fraction of the energetic cost that is involved in traditional liquid crystal-based devices. The insights presented in this work have the potential to provide a new fabrication platform to assemble low power bistable devices, which could be reconfigured upon application of small external fields.

Nanoscale chirality in metal and semiconductor nanoparticles.

Science.gov (United States)

Kumar, Jatish; Thomas, K George; Liz-Marzán, Luis M

2016-10-18

The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided.

Protein-material interactions: From micro-to-nano scale

International Nuclear Information System (INIS)

Tsapikouni, Theodora S.; Missirlis, Yannis F.

2008-01-01

The article presents a survey on the significance of protein-material interactions, the mechanisms which control them and the techniques used for their study. Protein-surface interactions play a key role in regenerative medicine, drug delivery, biosensor technology and chromatography, while it is related to various undesired effects such as biofouling and bio-prosthetic malfunction. Although the effects of protein-surface interaction concern the micro-scale, being sometimes obvious even with bare eyes, they derive from biophysical events at the nano-scale. The sequential steps for protein adsorption involve events at the single biomolecule level and the forces driving or inhibiting protein adsorption act at the molecular level too. Following the scaling of protein-surface interactions, various techniques have been developed for their study both in the micro- and nano-scale. Protein labelling with radioisotopes or fluorescent probes, colorimetric assays and the quartz crystal microbalance were the first techniques used to monitor protein adsorption isotherms, while the surface force apparatus was used to measure the interaction forces between protein layers at the micro-scale. Recently, more elaborate techniques like total internal reflection fluorescence (TIRF), Fourier transform infrared spectroscopy (FTIR), surface plasmon resonance, Raman spectroscopy, ellipsometry and time of flight secondary ion mass spectrometry (ToF-SIMS) have been applied for the investigation of protein density, structure or orientation at the interfaces. However, a turning point in the study of protein interactions with the surfaces was the invention and the wide-spread use of atomic force microscopy (AFM) which can both image single protein molecules on surfaces and directly measure the interaction force

Laser surface texturing of polymers for biomedical applications

Science.gov (United States)

Riveiro, Antonio; Maçon, Anthony L. B.; del Val, Jesus; Comesaña, Rafael; Pou, Juan

2018-02-01

Polymers are materials widely used in biomedical science because of their biocompatibility, and good mechanical properties (which, in some cases, are similar to those of human tissues); however, these materials are, in general, chemically and biologically inert. Surface characteristics, such as topography (at the macro-, micro, and nanoscale), surface chemistry, surface energy, charge or wettability are interrelated properties, and they cooperatively influence the biological performance of materials when used for biomedical applications. They regulate the biological response at the implant/tissue interface (e.g., influencing the cell adhesion, cell orientation, cell motility, etc.). Several surface processing techniques have been explored to modulate these properties for biomedical applications. Despite their potentials, these methods have limitations that prevent their applicability. In this regard, laser-based methods, in particular laser surface texturing (LST), can be an interesting alternative. Different works have showed the potentiality of this technique to control the surface properties of biomedical polymers and enhance their biological performance; however, more research is needed to obtain the desired biological response. This work provides a general overview of the basics and applications of LST for the surface modification of polymers currently used in the clinical practice (e.g. PEEK, UHMWPE, PP, etc.). The modification of roughness, wettability, and their impact on the biological response is addressed to offer new insights on the surface modification of biomedical polymers.

Contact materials for nanoelectronics

KAUST Repository

Alshareef, Husam N.

2011-02-01

In this article, we review current research activities in contact material development for electronic and nanoelectronic devices. A fundamental issue in contact materials research is to understand and control interfacial reactions and phenomena that modify the expected device performance. These reactions have become more challenging and more difficult to control as new materials have been introduced and as device sizes have entered the deep nanoscale. To provide an overview of this field of inquiry, this issue of MRS Bulletin includes articles on gate and contact materials for Si-based devices, junction contact materials for Si-based devices, and contact materials for alternate channel substrates (Ge and III-V), nanodevices. © 2011 Materials Research Society.

Electroless deposition and nanolithography can control the formation of materials at the nano-scale for plasmonic applications

KAUST Repository

Coluccio, Maria Laura; Gentile, Francesco; Francardi, Marco; Perozziello, Gerardo; Malara, Natalia; Candeloro, Patrizio; Di Fabrizio, Enzo M.

2014-01-01

The new revolution in materials science is being driven by our ability to manipulate matter at the molecular level to create structures with novel functions and properties. The aim of this paper is to explore new strategies to obtain plasmonic metal nanostructures through the combination of a top down method, that is electron beam lithography, and a bottom up technique, that is the chemical electroless deposition. This technique allows a tight control over the shape and size of bi- and three-dimensional metal patterns at the nano scale. The resulting nanostructures can be used as constituents of Surface Enhanced Raman Spectroscopy (SERS) substrates, where the electromagnetic field is strongly amplified. Our results indicate that, in electroless growth, high quality metal nanostructures with sizes below 50 nm may be easily obtained. These findings were explained within the framework of a diffusion limited aggregation (DLA) model, that is a simulation model that makes it possible to decipher, at an atomic level, the rules governing the evolution of the growth front; moreover, we give a description of the physical echanisms of growth at a basic level. In the discussion, we show how these findings can be utilized to fabricate dimers of silver nanospheres where the size and shape of those spheres is controlled with extreme precision and can be used for very large area SERS substrates and nano-optics, for single molecule detection. 2014 by the authors; licensee MDPI, Basel, Switzerland.

Electroless deposition and nanolithography can control the formation of materials at the nano-scale for plasmonic applications

KAUST Repository

Coluccio, Maria Laura

2014-03-27

The new revolution in materials science is being driven by our ability to manipulate matter at the molecular level to create structures with novel functions and properties. The aim of this paper is to explore new strategies to obtain plasmonic metal nanostructures through the combination of a top down method, that is electron beam lithography, and a bottom up technique, that is the chemical electroless deposition. This technique allows a tight control over the shape and size of bi- and three-dimensional metal patterns at the nano scale. The resulting nanostructures can be used as constituents of Surface Enhanced Raman Spectroscopy (SERS) substrates, where the electromagnetic field is strongly amplified. Our results indicate that, in electroless growth, high quality metal nanostructures with sizes below 50 nm may be easily obtained. These findings were explained within the framework of a diffusion limited aggregation (DLA) model, that is a simulation model that makes it possible to decipher, at an atomic level, the rules governing the evolution of the growth front; moreover, we give a description of the physical echanisms of growth at a basic level. In the discussion, we show how these findings can be utilized to fabricate dimers of silver nanospheres where the size and shape of those spheres is controlled with extreme precision and can be used for very large area SERS substrates and nano-optics, for single molecule detection. 2014 by the authors; licensee MDPI, Basel, Switzerland.

Electroless Deposition and Nanolithography Can Control the Formation of Materials at the Nano-Scale for Plasmonic Applications

Directory of Open Access Journals (Sweden)

Maria Laura Coluccio

2014-03-01

Full Text Available The new revolution in materials science is being driven by our ability to manipulate matter at the molecular level to create structures with novel functions and properties. The aim of this paper is to explore new strategies to obtain plasmonic metal nanostructures through the combination of a top down method, that is electron beam lithography, and a bottom up technique, that is the chemical electroless deposition. This technique allows a tight control over the shape and size of bi- and three-dimensional metal patterns at the nano scale. The resulting nanostructures can be used as constituents of Surface Enhanced Raman Spectroscopy (SERS substrates, where the electromagnetic field is strongly amplified. Our results indicate that, in electroless growth, high quality metal nanostructures with sizes below 50 nm may be easily obtained. These findings were explained within the framework of a diffusion limited aggregation (DLA model, that is a simulation model that makes it possible to decipher, at an atomic level, the rules governing the evolution of the growth front; moreover, we give a description of the physical mechanisms of growth at a basic level. In the discussion, we show how these findings can be utilized to fabricate dimers of silver nanospheres where the size and shape of those spheres is controlled with extreme precision and can be used for very large area SERS substrates and nano-optics, for single molecule detection.

Nanoscale Synthesis and Characterization Laboratory Annual Report 2005

Energy Technology Data Exchange (ETDEWEB)

Hamza, A V; Lesuer, D R

2006-01-03

The Nanoscale Synthesis and Characterization Laboratory's (NSCL) primary mission is to create and advance interdisciplinary research and development opportunities in nanoscience and technology. The initial emphasis of the NSCL has been on development of scientific solutions in support of target fabrication for the NIF laser and other stockpile stewardship experimental platforms. Particular emphasis has been placed on the design and development of innovative new materials and structures for use in these targets. Projects range from the development of new high strength nanocrystalline alloys to graded density materials to high Z nanoporous structures. The NSCL also has a mission to recruit and train personnel for Lab programs such as the National Ignition Facility (NIF), Defense and Nuclear Technologies (DNT), and Nonproliferation, Arms control and International security (NAI). The NSCL continues to attract talented scientists to the Laboratory.

Advancing Risk Analysis for Nanoscale Materials: Report from an International Workshop on the Role of Alternative Testing Strategies for Advancement: Advancing Risk Analysis for Nanoscale Materials

Energy Technology Data Exchange (ETDEWEB)

Shatkin, J. A. [Vireo Advisors, Boston MA USA; Ong, Kimberly J. [Vireo Advisors, Boston MA USA; Beaudrie, Christian [Compass RM, Vancouver CA USA; Clippinger, Amy J. [PETA International Science Consortium Ltd, London UK; Hendren, Christine Ogilvie [Center for the Environmental Implications of NanoTechnology, Duke University, Durham NC USA; Haber, Lynne T. [TERA, Cincinnati OH USA; Hill, Myriam [Health Canada, Ottawa Canada; Holden, Patricia [UC Santa Barbara, Bren School of Environmental Science & Management, ERI, and UC CEIN, University of California, Santa Barbara CA USA; Kennedy, Alan J. [U.S. Army Engineer Research and Development Center, Environmental Laboratory, Vicksburg MS USA; Kim, Baram [Independent, Somerville MA USA; MacDonell, Margaret [Argonne National Laboratory, Environmental Science Division, Argonne IL USA; Powers, Christina M. [U.S. Environmental Protection Agency, Office of Air and Radiation, Office of Transportation and Air Quality, Ann Arbor MI USA; Sharma, Monita [PETA International Science Consortium Ltd, London UK; Sheremeta, Lorraine [Alberta Ingenuity Labs, Edmonton Alberta Canada; Stone, Vicki [John Muir Building Gait 1 Heriot-Watt University, Edinburgh Scotland UK; Sultan, Yasir [Environment Canada, Gatineau QC Canada; Turley, Audrey [ICF International, Durham NC USA; White, Ronald H. [RH White Consultants, Silver Spring MD USA

2016-08-01

The Society for Risk Analysis (SRA) has a history of bringing thought leadership to topics of emerging risk. In September 2014, the SRA Emerging Nanoscale Materials Specialty Group convened an international workshop to examine the use of alternative testing strategies (ATS) for manufactured nanomaterials (NM) from a risk analysis perspective. Experts in NM environmental health and safety, human health, ecotoxicology, regulatory compliance, risk analysis, and ATS evaluated and discussed the state of the science for in vitro and other alternatives to traditional toxicology testing for NM. Based on this review, experts recommended immediate and near-term actions that would advance ATS use in NM risk assessment. Three focal areas-human health, ecological health, and exposure considerations-shaped deliberations about information needs, priorities, and the next steps required to increase confidence in and use of ATS in NM risk assessment. The deliberations revealed that ATS are now being used for screening, and that, in the near term, ATS could be developed for use in read-across or categorization decision making within certain regulatory frameworks. Participants recognized that leadership is required from within the scientific community to address basic challenges, including standardizing materials, protocols, techniques and reporting, and designing experiments relevant to real-world conditions, as well as coordination and sharing of large-scale collaborations and data. Experts agreed that it will be critical to include experimental parameters that can support the development of adverse outcome pathways. Numerous other insightful ideas for investment in ATS emerged throughout the discussions and are further highlighted in this article.

Highly repeatable nanoscale phase coexistence in vanadium dioxide films

Science.gov (United States)

Huffman, T. J.; Lahneman, D. J.; Wang, S. L.; Slusar, T.; Kim, Bong-Jun; Kim, Hyun-Tak; Qazilbash, M. M.

2018-02-01

It is generally believed that in first-order phase transitions in materials with imperfections, the formation of phase domains must be affected to some extent by stochastic (probabilistic) processes. The stochasticity would lead to unreliable performance in nanoscale devices that have the potential to exploit the transformation of physical properties in a phase transition. Here we show that stochasticity at nanometer length scales is completely suppressed in the thermally driven metal-insulator transition (MIT) in sputtered vanadium dioxide (V O2 ) films. The nucleation and growth of domain patterns of metallic and insulating phases occur in a strikingly reproducible way. The completely deterministic nature of domain formation and growth in films with imperfections is a fundamental and unexpected finding about the kinetics of this material. Moreover, it opens the door for realizing reliable nanoscale devices based on the MIT in V O2 and similar phase-change materials.

Ultrafast Bessel beams: advanced tools for laser materials processing

Science.gov (United States)

Stoian, Razvan; Bhuyan, Manoj K.; Zhang, Guodong; Cheng, Guanghua; Meyer, Remy; Courvoisier, Francois

2018-05-01

Ultrafast Bessel beams demonstrate a significant capacity of structuring transparent materials with a high degree of accuracy and exceptional aspect ratio. The ability to localize energy on the nanometer scale (bypassing the 100-nm milestone) makes them ideal tools for advanced laser nanoscale processing on surfaces and in the bulk. This allows to generate and combine micron and nano-sized features into hybrid structures that show novel functionalities. Their high aspect ratio and the accurate location can equally drive an efficient material modification and processing strategy on large dimensions. We review, here, the main concepts of generating and using Bessel non-diffractive beams and their remarkable features, discuss general characteristics of their interaction with matter in ablation and material modification regimes, and advocate their use for obtaining hybrid micro and nanoscale structures in two and three dimensions (2D and 3D) performing complex functions. High-throughput applications are indicated. The example list ranges from surface nanostructuring and laser cutting to ultrafast laser welding and the fabrication of 3D photonic systems embedded in the volume.

Nanoscale Engineering in VO2 Nanowires via Direct Electron Writing Process.

Science.gov (United States)

Zhang, Zhenhua; Guo, Hua; Ding, Wenqiang; Zhang, Bin; Lu, Yue; Ke, Xiaoxing; Liu, Weiwei; Chen, Furong; Sui, Manling

2017-02-08

Controlling phase transition in functional materials at nanoscale is not only of broad scientific interest but also important for practical applications in the fields of renewable energy, information storage, transducer, sensor, and so forth. As a model functional material, vanadium dioxide (VO 2 ) has its metal-insulator transition (MIT) usually at a sharp temperature around 68 °C. Here, we report a focused electron beam can directly lower down the transition temperature of a nanoarea to room temperature without prepatterning the VO 2 . This novel process is called radiolysis-assisted MIT (R-MIT). The electron beam irradiation fabricates a unique gradual MIT zone to several times of the beam size in which the temperature-dependent phase transition is achieved in an extended temperature range. The gradual transformation zone offers to precisely control the ratio of metal/insulator phases. This direct electron writing technique can open up an opportunity to precisely engineer nanodomains of diversified electronic properties in functional material-based devices.

Physical adsorption at the nanoscale: Towards controllable scaling of the substrate-adsorbate van der Waals interaction

Science.gov (United States)

Ambrosetti, Alberto; Silvestrelli, Pier Luigi; Tkatchenko, Alexandre

2017-06-01

The Lifshitz-Zaremba-Kohn (LZK) theory is commonly considered as the correct large-distance limit for the van der Waals (vdW) interaction of adsorbates (atoms, molecules, or nanoparticles) with solid substrates. In the standard approximate form, implicitly based on local dielectric functions, the LZK approach predicts universal power laws for vdW interactions depending only on the dimensionality of the interacting objects. However, recent experimental findings are challenging the universality of this theoretical approach at finite distances of relevance for nanoscale assembly. Here, we present a combined analytical and numerical many-body study demonstrating that physical adsorption can be significantly enhanced at the nanoscale. Regardless of the band gap or the nature of the adsorbate specie, we find deviations from conventional LZK power laws that extend to separation distances of up to 10-20 nm. Comparison with recent experimental observations of ultra-long-ranged vdW interactions in the delamination of graphene from a silicon substrate reveals qualitative agreement with the present theory. The sensitivity of vdW interactions to the substrate response and to the adsorbate characteristic excitation frequency also suggests that adsorption strength can be effectively tuned in experiments, paving the way to an improved control of physical adsorption at the nanoscale.

Molecular dynamics simulation of self-diffusion processes in titanium in bulk material, on grain junctions and on surface.

Science.gov (United States)

Sushko, Gennady B; Verkhovtsev, Alexey V; Yakubovich, Alexander V; Schramm, Stefan; Solov'yov, Andrey V

2014-08-21

The process of self-diffusion of titanium atoms in a bulk material, on grain junctions and on surface is explored numerically in a broad temperature range by means of classical molecular dynamics simulation. The analysis is carried out for a nanoscale cylindrical sample consisting of three adjacent sectors and various junctions between nanocrystals. The calculated diffusion coefficient varies by several orders of magnitude for different regions of the sample. The calculated values of the bulk diffusion coefficient correspond reasonably well to the experimental data obtained for solid and molten states of titanium. Investigation of diffusion in the nanocrystalline titanium is of a significant importance because of its numerous technological applications. This paper aims to reduce the lack of data on diffusion in titanium and describe the processes occurring in bulk, at different interfaces and on surface of the crystalline titanium.

Nanoscale surface modifications to control capillary flow characteristics in PMMA microfluidic devices

Directory of Open Access Journals (Sweden)

Mukhopadhyay Subhadeep

2011-01-01

Full Text Available Abstract Polymethylmethacrylate (PMMA microfluidic devices have been fabricated using a hot embossing technique to incorporate micro-pillar features on the bottom wall of the device which when combined with either a plasma treatment or the coating of a diamond-like carbon (DLC film presents a range of surface modification profiles. Experimental results presented in detail the surface modifications in the form of distinct changes in the static water contact angle across a range from 44.3 to 81.2 when compared to pristine PMMA surfaces. Additionally, capillary flow of water (dyed to aid visualization through the microfluidic devices was recorded and analyzed to provide comparison data between filling time of a microfluidic chamber and surface modification characteristics, including the effects of surface energy and surface roughness on the microfluidic flow. We have experimentally demonstrated that fluid flow and thus filling time for the microfluidic device was significantly faster for the device with surface modifications that resulted in a lower static contact angle, and also that the incorporation of micro-pillars into a fluidic device increases the filling time when compared to comparative devices.

Comparison of Micro- and Nanoscale Fe+3-Containing (Hematite) Particles for Their Toxicological Properties in Human Lung Cells In Vitro

NARCIS (Netherlands)

Bhattacharya, K.; Hoffmann, E.; Schins, R.F.P.; Boertz, J.; Prantl, E.M.; Alink, G.M.; Byrne, H.J.; Kuhlbusch, T.A.J.; Rahman, Q.; Wiggers, H.; Schulz, C.; Dopp, E.

2012-01-01

The specific properties of nanoscale particles, large surface-to-mass ratios and highly reactive surfaces, have increased their commercial application in many fields. However, the same properties are also important for the interaction and bioaccumulation of the nonbiodegradable nanoscale particles

Nanoscale materials in chemistry

National Research Council Canada - National Science Library

Klabunde, Kenneth J; Richards, Ryan

2009-01-01

...: Disordered, Porous Nanostructures Stephanie L. Brock 209 9 Ordered Microporous and Mesoporous Materials Freddy Kleitz 243 10 Applications of Microporous and Mesoporous Materials Anirban Ghosh,...

Systems engineering at the nanoscale

Science.gov (United States)

Benkoski, Jason J.; Breidenich, Jennifer L.; Wei, Michael C.; Clatterbaughi, Guy V.; Keng, Pei Yuin; Pyun, Jeffrey

2012-06-01

Nanomaterials have provided some of the greatest leaps in technology over the past twenty years, but their relatively early stage of maturity presents challenges for their incorporation into engineered systems. Perhaps even more challenging is the fact that the underlying physics at the nanoscale often run counter to our physical intuition. The current state of nanotechnology today includes nanoscale materials and devices developed to function as components of systems, as well as theoretical visions for "nanosystems," which are systems in which all components are based on nanotechnology. Although examples will be given to show that nanomaterials have indeed matured into applications in medical, space, and military systems, no complete nanosystem has yet been realized. This discussion will therefore focus on systems in which nanotechnology plays a central role. Using self-assembled magnetic artificial cilia as an example, we will discuss how systems engineering concepts apply to nanotechnology.

Enhancement of CNT/PET film adhesion by nano-scale modification for flexible all-solid-state supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Kang, Yu Jin [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Chung, Haegeun [Department of Environmental Engineering, Konkuk University, Seoul 143-701 (Korea, Republic of); Kim, Min-Seop [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Kim, Woong, E-mail: woongkim@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

2015-11-15

Graphical abstract: - Highlights: • High integrity supercapacitors are achieved by improving adhesion of CNTs on PET. • Nanostructures on PET substrate significantly enhances the adhesion strength. • A simple RIE process generates the nanostructures on PET surface. • RIE induces hydrophilicity on the PET and further enhances the adhesive strength. • The supercapacitors show good cyclability with high specific capacitance retention. - Abstract: We demonstrate the fabrication of high-integrity flexible supercapacitors using carbon nanotubes (CNTs), polyethylene terephthalate (PET) films, and ion gels. Although both CNTs and PET films are attractive materials for flexible electronics, they have poor adhesion properties. In this work, we significantly improve interfacial adhesion by introducing nanostructures at the interface of the CNT and PET layers. Simple reactive ion etching (RIE) of the PET substrates generates nano-scale roughness on the PET surface. RIE also induces hydrophilicity on the PET surface, which further enhances adhesive strength. The improved adhesion enables high integrity and excellent flexibility of the fabricated supercapacitors, demonstrated over hundreds of bending cycles. Furthermore, the supercapacitors show good cyclability with specific capacitance retention of 87.5% after 10,000 galvanostatic charge–discharge (GCD) cycles. Our demonstration may be important for understanding interfacial adhesion properties in nanoscale and for producing flexible, high-integrity, high-performance energy storage systems.

Enhancement of CNT/PET film adhesion by nano-scale modification for flexible all-solid-state supercapacitors

International Nuclear Information System (INIS)

Kang, Yu Jin; Chung, Haegeun; Kim, Min-Seop; Kim, Woong

2015-01-01

Graphical abstract: - Highlights: • High integrity supercapacitors are achieved by improving adhesion of CNTs on PET. • Nanostructures on PET substrate significantly enhances the adhesion strength. • A simple RIE process generates the nanostructures on PET surface. • RIE induces hydrophilicity on the PET and further enhances the adhesive strength. • The supercapacitors show good cyclability with high specific capacitance retention. - Abstract: We demonstrate the fabrication of high-integrity flexible supercapacitors using carbon nanotubes (CNTs), polyethylene terephthalate (PET) films, and ion gels. Although both CNTs and PET films are attractive materials for flexible electronics, they have poor adhesion properties. In this work, we significantly improve interfacial adhesion by introducing nanostructures at the interface of the CNT and PET layers. Simple reactive ion etching (RIE) of the PET substrates generates nano-scale roughness on the PET surface. RIE also induces hydrophilicity on the PET surface, which further enhances adhesive strength. The improved adhesion enables high integrity and excellent flexibility of the fabricated supercapacitors, demonstrated over hundreds of bending cycles. Furthermore, the supercapacitors show good cyclability with specific capacitance retention of 87.5% after 10,000 galvanostatic charge–discharge (GCD) cycles. Our demonstration may be important for understanding interfacial adhesion properties in nanoscale and for producing flexible, high-integrity, high-performance energy storage systems.

Gas Selectivity Control in Co3O4 Sensor via Concurrent Tuning of Gas Reforming and Gas Filtering using Nanoscale Hetero-Overlayer of Catalytic Oxides.

Science.gov (United States)

Jeong, Hyun-Mook; Jeong, Seong-Yong; Kim, Jae-Hyeok; Kim, Bo-Young; Kim, Jun-Sik; Abdel-Hady, Faissal; Wazzan, Abdulaziz A; Al-Turaif, Hamad Ali; Jang, Ho Won; Lee, Jong-Heun

2017-11-29

Co 3 O 4 sensors with a nanoscale TiO 2 or SnO 2 catalytic overlayer were prepared by screen-printing of Co 3 O 4 yolk-shell spheres and subsequent e-beam evaporation of TiO 2 and SnO 2 . The Co 3 O 4 sensors with 5 nm thick TiO 2 and SnO 2 overlayers showed high responses (resistance ratios) to 5 ppm xylene (14.5 and 28.8) and toluene (11.7 and 16.2) at 250 °C with negligible responses to interference gases such as ethanol, HCHO, CO, and benzene. In contrast, the pure Co 3 O 4 sensor did not show remarkable selectivity toward any specific gas. The response and selectivity to methylbenzenes and ethanol could be systematically controlled by selecting the catalytic overlayer material, varying the overlayer thickness, and tuning the sensing temperature. The significant enhancement of the selectivity for xylene and toluene was attributed to the reforming of less reactive methylbenzenes into more reactive and smaller species and oxidative filtering of other interference gases, including ubiquitous ethanol. The concurrent control of the gas reforming and oxidative filtering processes using a nanoscale overlayer of catalytic oxides provides a new, general, and powerful tool for designing highly selective and sensitive oxide semiconductor gas sensors.

Control of the Shell Thickness of TiO{sub 2} SiO{sub 2} Particles and Its Surface Functionalization

Energy Technology Data Exchange (ETDEWEB)

Ahn, Junho; Jung, Sung Ho; Lee, Ji Ha; Kwon, Kiyoung; Jung, Jong Hwa [Gyeongsang National Univ., Jinju (Korea, Republic of)

2013-11-15

TiO{sub 2} SiO{sub 2} yolk/core shell particles were obtained by a sol-gel polymerization. The shell thickness of TiO{sub 2} SiO{sub 2} can successfully be controlled by sol-gel reaction times. The anatase structure of TiO{sub 2} SiO{sub 2} was more stable than that of TiO{sub 2} particles calcinated at higher temperature. Moreover, acrylate-functionalized TiO{sub 2} SiO{sub 2} particles were also successfully synthesized using the TiO{sub 2} SiO{sub 2} particles as building blocks by copolymerization of trimethoxysilyl groups of MPA with the existing hydroxyl groups on the surface of TiO{sub 2} SiO{sub 2} particles. Furthermore, TEM, EDX, and FTIR studies confirmed that MPA had been successfully grafted to the surface of TiO{sub 2} SiO{sub 2} particles. Finally, we believe that the present results showing the development of surface functionalized particles can be very useful in the fields of various functional applications, and could be extended to more sophisticated hybrid materials.The fabrication of functional hollow particles is of great scientific and technological interest for purposes of applications ranging from drug delivery, coatings, photonic devices, and nanoscale reaction vessels. Various methods, including approaches such as spray drying, emulsion templating techniques, and self-assembly processes, have been described for the preparation of hollow spheres out of latex, metal, and inorganic materials.

Nanoscale electron manipulation in metals with intense THz electric fields

Science.gov (United States)

Takeda, Jun; Yoshioka, Katsumasa; Minami, Yasuo; Katayama, Ikufumi

2018-03-01

Improved control over the electromagnetic properties of metals on a nanoscale is crucial for the development of next-generation nanoelectronics and plasmonic devices. Harnessing the terahertz (THz)-electric-field-induced nonlinearity for the motion of electrons is a promising method of manipulating the local electromagnetic properties of metals, while avoiding undesirable thermal effects and electronic transitions. In this review, we demonstrate the manipulation of electron delocalization in ultrathin gold (Au) films with nanostructures, by intense THz electric-field transients. On increasing the electric-field strength of the THz pulses, the transmittance in the THz-frequency region abruptly decreases around the percolation threshold. The observed THz-electric-field-induced nonlinearity is analysed, based on the Drude-Smith model. The results suggest that ultrafast electron delocalization occurs by electron tunnelling across the narrow insulating bridge between the Au nanostructures, without material breakdown. In order to quantitatively discuss the tunnelling process, we perform scanning tunnelling microscopy with carrier-envelope phase (CEP)-controlled single-cycle THz electric fields. By applying CEP-controlled THz electric fields to the 1 nm nanogap between a metal nanotip and graphite sample, many electrons could be coherently driven through the quantum tunnelling process, either from the nanotip to the sample or vice versa. The presented concept, namely, electron tunnelling mediated by CEP-controlled single-cycle THz electric fields, can facilitate the development of nanoscale electron manipulation, applicable to next-generation ultrafast nanoelectronics and plasmonic devices.

Surface-modified multifunctional MIP nanoparticles

Science.gov (United States)

Moczko, Ewa; Poma, Alessandro; Guerreiro, Antonio; Perez de Vargas Sansalvador, Isabel; Caygill, Sarah; Canfarotta, Francesco; Whitcombe, Michael J.; Piletsky, Sergey

2013-04-01

The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as a protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity (PEG methacrylate); electro-activity (vinylferrocene); fluorescence (eosin acrylate); thiol groups (pentaerythritol tetrakis(3-mercaptopropionate)). The method has broad applicability and can be used to produce multifunctional imprinted nanoparticles with potential for further application in the biosensors, diagnostics and biomedical fields and as an alternative to natural receptors.The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as a protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity

In-situ materials characterization across spatial and temporal scales

CERN Document Server

Graafsma, Heinz; Zhang, Xiao; Frenken, Joost

2014-01-01

The behavior of nanoscale materials can change rapidly with time either because the environment changes rapidly, or because the influence of the environment propagates quickly across the intrinsically small dimensions of nanoscale materials. Extremely fast time resolution studies using X-rays, electrons and neutrons are of very high interest to many researchers and is a fast-evolving and interesting field for the study of dynamic processes. Therefore, in situ structural characterization and measurements of structure-property relationships covering several decades of length and time scales (from atoms to millimeters and femtoseconds to hours) with high spatial and temporal resolutions are crucially important to understand the synthesis and behavior of multidimensional materials. The techniques described in this book will permit access to the real-time dynamics of materials, surface processes, and chemical and biological reactions at various time scales. This book provides an interdisciplinary reference for res...

The use of abrasive polishing and laser processing for developing polyurethane surfaces for controlling fibroblast cell behaviour

Energy Technology Data Exchange (ETDEWEB)

Irving, Michael; Murphy, Mark F; Lilley, Francis; French, Paul W; Burton, David R [General Engineering Research Institute, Liverpool John Moores University, Liverpool, L3 3AF (United Kingdom); Dixon, Simon [Biomer Technology LTD, 10 Seymour Court, Tudor Road, Manor Park, Runcorn, Cheshire, WA7 1SY (United Kingdom); Sharp, Martin C [General Engineering Research Institute, Liverpool John Moores University, Liverpool, L3 3AF (United Kingdom)

2017-02-01

Studies have shown that surfaces having micro and nano-scale features can be used to control cell behaviours including; cell proliferation, migration and adhesion. The aim of this work was to compare the use of laser processing and abrasive polishing to develop micro/nano-patterned polyurethane substrates for controlling fibroblast cell adhesion, migration and proliferation. Laser processing in a directional manner resulted in polyurethane surfaces having a ploughed field effect with micron-scale features. In contrast, abrasive polishing in a directional and random manner resulted in polyurethane surfaces having sub-micron scale features orientated in a linear or random manner. Results show that when compared with flat (non-patterned) polymer, both the laser processed and abrasive polished surface having randomly organised features, promoted significantly greater cell adhesion, while also enhancing cell proliferation after 72 h. In contrast, the abrasive polished surface having linear features did not enhance cell adhesion or proliferation when compared to the flat surface. For cell migration, the cells growing on the laser processed and abrasively polished random surface showed decreased levels of migration when compared to the flat surface. This study shows that both abrasive polishing and laser processing can be used to produce surfaces having features on the nano-scale and micron-scale, respectively. Surfaces produced using both techniques can be used to promote fibroblast cell adhesion and proliferation. Thus both methods offer a viable alternative to using lithographic techniques for developing patterned surfaces. In particular, abrasive polishing is an attractive method due to it being a simple, rapid and inexpensive method that can be used to produce surfaces having features on a comparable scale to more expensive, multi-step methods. - Highlights: • Abrasive polishing can generate nano-scratches on stainless steel to cast polymer films for cell

The use of abrasive polishing and laser processing for developing polyurethane surfaces for controlling fibroblast cell behaviour

International Nuclear Information System (INIS)

Irving, Michael; Murphy, Mark F; Lilley, Francis; French, Paul W; Burton, David R; Dixon, Simon; Sharp, Martin C

2017-01-01

Studies have shown that surfaces having micro and nano-scale features can be used to control cell behaviours including; cell proliferation, migration and adhesion. The aim of this work was to compare the use of laser processing and abrasive polishing to develop micro/nano-patterned polyurethane substrates for controlling fibroblast cell adhesion, migration and proliferation. Laser processing in a directional manner resulted in polyurethane surfaces having a ploughed field effect with micron-scale features. In contrast, abrasive polishing in a directional and random manner resulted in polyurethane surfaces having sub-micron scale features orientated in a linear or random manner. Results show that when compared with flat (non-patterned) polymer, both the laser processed and abrasive polished surface having randomly organised features, promoted significantly greater cell adhesion, while also enhancing cell proliferation after 72 h. In contrast, the abrasive polished surface having linear features did not enhance cell adhesion or proliferation when compared to the flat surface. For cell migration, the cells growing on the laser processed and abrasively polished random surface showed decreased levels of migration when compared to the flat surface. This study shows that both abrasive polishing and laser processing can be used to produce surfaces having features on the nano-scale and micron-scale, respectively. Surfaces produced using both techniques can be used to promote fibroblast cell adhesion and proliferation. Thus both methods offer a viable alternative to using lithographic techniques for developing patterned surfaces. In particular, abrasive polishing is an attractive method due to it being a simple, rapid and inexpensive method that can be used to produce surfaces having features on a comparable scale to more expensive, multi-step methods. - Highlights: • Abrasive polishing can generate nano-scratches on stainless steel to cast polymer films for cell

Surface PEGylation of mesoporous silica materials via surface-initiated chain transfer free radical polymerization: Characterization and controlled drug release.

Science.gov (United States)

Huang, Long; Liu, Meiying; Mao, Liucheng; Huang, Qiang; Huang, Hongye; Wan, Qing; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

2017-12-01

As a new type of mesoporous silica materials with large pore diameter (pore size between 2 and 50nm) and high specific surface areas, SBA-15 has been widely explored for different applications especially in the biomedical fields. The surface modification of SBA-15 with functional polymers has demonstrated to be an effective way for improving its properties and performance. In this work, we reported the preparation of PEGylated SBA-15 polymer composites through surface-initiated chain transfer free radical polymerization for the first time. The thiol group was first introduced on SBA-15 via co-condensation with γ-mercaptopropyltrimethoxysilane (MPTS), that were utilized to initiate the chain transfer free radical polymerization using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and itaconic acid (IA) as the monomers. The successful modification of SBA-15 with poly(PEGMA-co-IA) copolymers was evidenced by a series of characterization techniques, including 1 H NMR, FT-IR, TGA and XPS. The final SBA-15-SH- poly(PEGMA-co-IA) composites display well water dispersity and high loading capability towards cisplatin (CDDP) owing to the introduction of hydrophilic PEGMA and carboxyl groups. Furthermore, the CDDP could be released from SBA-15-SH-poly(PEGMA-co-IA)-CDDP complexes in a pH dependent behavior, suggesting the potential controlled drug delivery of SBA-15-SH-poly(PEGMA-co-IA). More importantly, the strategy should be also useful for fabrication of many other functional materials for biomedical applications owing to the advantages of SBA-15 and well monomer adoptability of chain transfer free radical polymerization. Copyright © 2017 Elsevier B.V. All rights reserved.

Formation of patterned arrays of Au nanoparticles on SiC surface by template confined dewetting of normal and oblique deposited nanoscale films

Energy Technology Data Exchange (ETDEWEB)

Ruffino, F., E-mail: francesco.ruffino@ct.infn.it; Grimaldi, M.G.

2013-06-01

We report on the formation of patterned arrays of Au nanoparticles (NPs) on 6H SiC surface. To this end, we exploit the thermal-induced dewetting properties of a template confined deposited nanoscale Au film. In this approach, the Au surface pattern order, on the SiC substrate, is established by a template confined deposition using a micrometric template. Then, a dewetting process of the patterned Au film is induced by thermal processes. We compare the results, about the patterns formation, obtained for normal and oblique deposited Au films. We show that the normal and oblique depositions, through the same template, originate different patterns of the Au film. As a consequence of these different starting patterns, after the thermal processes, different patterns for the arrays of NPs originating from the dewetting mechanisms are obtained. For each fixed deposition angle α, the pattern evolution is analyzed, by scanning electron microscopy, as a function of the annealing time at 1173 K (900 °C). From these analyses, quantitative evaluations on the NPs size evolution are drawn. - Highlights: • Micrometric template-confined nanoscale gold films are deposited on silicon carbide. • The dewetting process of template-confined gold films on silicon carbide is studied. • Comparison of dewetting process of normal and oblique deposited gold films is drawn. • Patterned arrays of gold nanoparticles on silicon carbide surface are produced.

Formation of patterned arrays of Au nanoparticles on SiC surface by template confined dewetting of normal and oblique deposited nanoscale films

International Nuclear Information System (INIS)

Ruffino, F.; Grimaldi, M.G.

2013-01-01

We report on the formation of patterned arrays of Au nanoparticles (NPs) on 6H SiC surface. To this end, we exploit the thermal-induced dewetting properties of a template confined deposited nanoscale Au film. In this approach, the Au surface pattern order, on the SiC substrate, is established by a template confined deposition using a micrometric template. Then, a dewetting process of the patterned Au film is induced by thermal processes. We compare the results, about the patterns formation, obtained for normal and oblique deposited Au films. We show that the normal and oblique depositions, through the same template, originate different patterns of the Au film. As a consequence of these different starting patterns, after the thermal processes, different patterns for the arrays of NPs originating from the dewetting mechanisms are obtained. For each fixed deposition angle α, the pattern evolution is analyzed, by scanning electron microscopy, as a function of the annealing time at 1173 K (900 °C). From these analyses, quantitative evaluations on the NPs size evolution are drawn. - Highlights: • Micrometric template-confined nanoscale gold films are deposited on silicon carbide. • The dewetting process of template-confined gold films on silicon carbide is studied. • Comparison of dewetting process of normal and oblique deposited gold films is drawn. • Patterned arrays of gold nanoparticles on silicon carbide surface are produced

Controlling Beryllium Contaminated Material And Equipment For The Building 9201-5 Legacy Material Disposition Project

International Nuclear Information System (INIS)

Reynolds, T.D.; Easterling, S.D.

2010-01-01

This position paper addresses the management of beryllium contamination on legacy waste. The goal of the beryllium management program is to protect human health and the environment by preventing the release of beryllium through controlling surface contamination. Studies have shown by controlling beryllium surface contamination, potential airborne contamination is reduced or eliminated. Although there are areas in Building 9201-5 that are contaminated with radioactive materials and mercury, only beryllium contamination is addressed in this management plan. The overall goal of this initiative is the compliant packaging and disposal of beryllium waste from the 9201-5 Legacy Material Removal (LMR) Project to ensure that beryllium surface contamination and any potential airborne release of beryllium is controlled to levels as low as practicable in accordance with 10 CFR 850.25.

Surface reconstruction: An effective method for the growth of mismatched materials

Energy Technology Data Exchange (ETDEWEB)

Sun, Yu; Zheng, Beining; Wu, Xiaofeng; Yuan, Long; Wu, Jie; Guo, Hongping; Huang, Keke; Feng, Shouhua, E-mail: shfeng@mail.jlu.edu.cn

2016-01-01

Graphical abstract: High quality thin film of GaSb was fabricated with molecular beam epitaxy technique on the reconstructed Si(1 1 1) surface. - Highlights: • Surface reconstruction formed by different surface treatments controls the heteroepitaxial growth. • Mismatched stress can be effectively released when the mismatched material epi-film tilts out of the epitaxial interface plane to create a coincidence-site lattice. • GaSb films grown on Si(1 1 1)-(5√3 × 5√3)-Sb surface show better crystal quality and morphology for its self-assembled 2D fishbone structure. - Abstract: The crystalline quality of epitaxial films depends on the degree of lattice match between substrates and films. Here, we report a growth strategy for large mismatched epi-films to grow GaSb films on Si(1 1 1) substrates. The epitaxial strategy can be influenced by controlling the surface reconstructions of Sb-treated Si(1 1 1). The film with the best quality was grown on Si(1 1 1)-(5√3 × 5√3)-Sb surface due to the stress release and the formation of a self-assembled 2D fishbone structure. Controlled surface engineering provides an effective pathway towards the growth of the large mismatched materials.

Microprocessor-controlled surface testing

Energy Technology Data Exchange (ETDEWEB)

Droscha, H

1982-09-01

For the quality inspection on continuous flow material webs with transverse scanning laser beam, the microprocessor control, realized now for the first time in combination with appropriate units, shows a considerable progress. Thanks to the here used electronics, surface errors can be localized within the web according to their x-y-position, quantitative analysis can be carried out and automatic sorting and registration functions can be used.

Spatiotemporal control over molecular delivery and cellular encapsulation from electropolymerized micro- and nanopatterned surfaces.

Science.gov (United States)

Stern, Eric; Jay, Steven M; Demento, Stacey L; Murelli, Ryan P; Reed, Mark A; Malinski, Tadeusz; Spiegel, David A; Mooney, David J; Fahmy, Tarek M

2009-07-13

Bioactive, patterned micro- and nanoscale surfaces that can be spatially engineered for three-dimensional ligand presentation and sustained release of signaling molecules represent a critical advance for the development of next-generation diagnostic and therapeutic devices. Lithography is ideally suited to patterning such surfaces due to its precise, easily scalable, high-throughput nature; however, to date polymers patterned by these techniques have not demonstrated the capacity for sustained release of bioactive agents. We demonstrate here a class of lithographically-defined, electropolymerized polymers with monodisperse micro- and nanopatterned features capable of sustained release of bioactive drugs and proteins. We show that precise control can be achieved over the loading capacity and release rates of encapsulated agents and illustrate this aspect using a fabricated surface releasing a model antigen (ovalbumin) and a cytokine (interleukin-2) for induction of a specific immune response. We further demonstrate the ability of this technique to enable three-dimensional control over cellular encapsulation. The efficacy of the described approach is buttressed by its simplicity, versatility, and reproducibility, rendering it ideally suited for biomaterials engineering.

Methods and devices for fabricating three-dimensional nanoscale structures

Science.gov (United States)

Rogers, John A.; Jeon, Seokwoo; Park, Jangung

2010-04-27

The present invention provides methods and devices for fabricating 3D structures and patterns of 3D structures on substrate surfaces, including symmetrical and asymmetrical patterns of 3D structures. Methods of the present invention provide a means of fabricating 3D structures having accurately selected physical dimensions, including lateral and vertical dimensions ranging from 10s of nanometers to 1000s of nanometers. In one aspect, methods are provided using a mask element comprising a conformable, elastomeric phase mask capable of establishing conformal contact with a radiation sensitive material undergoing photoprocessing. In another aspect, the temporal and/or spatial coherence of electromagnetic radiation using for photoprocessing is selected to fabricate complex structures having nanoscale features that do not extend entirely through the thickness of the structure fabricated.

NANOINTERACT: A rational approach to the interaction between nanoscale materials and living matter?

International Nuclear Information System (INIS)

Lynch, Iseult; Linse, Sara; Howard, C Vyvyan; Stepnik, Maciej; Rydzynski, Konrad; Hanrahan, John; Jong, Wim de; Langevin, Dominique; Raedler, Joachim; Parak, Wolfgang; Volkov, Yuri; Radomski, Marek; Thomas, Robert; Klein, Jacob; Barron, Andrew A; Janssen, Colin; Lyons, Fiona M; Quinn, Francis; Swennen, Bert; Cuypers, Peter

2009-01-01

The importance of understanding the interactions between nanoscale materials and living matter has now begun to be appreciated by an extraordinaryly large range of stakeholders, including researchers, industry, governments and society, all of whom appreciate both the opportunities presented by and challenges raised by this arena of research. Not only does it open up new directions in nanomedicine and nanodiagnostics, but it also offers the chance to implement nanotechnology across all industry in a safe and responsible manner. The underlying reasons for this arena as a new scientific paradigm are real and durable. Less than 100 nm nanoparticles can enter cells, less that 40 nm they can enter cell nucleus, and less that 35 nm they can pass through the blood brain barrier. These are fundamental length scales of biological relevance that will ensure that engineered nanoscience will impinge on biology and medicine for many decades to come. One important issue is the current lack of reproducibility of the outcomes of many experiments in this arena. Differences are likely a consequence of such things as uncontrolled nanoparticle aggregation leading to unpredictable doses being presented to cells, interference of the nanoparticles themselves with many of the tests being applied, differences in the degree of confluency of the cells used, and a host of other factors. NanoInteract has shown how careful control of all aspects of the test system, combined with round robin type approaches, can help resolve these issues and begin to ensure that the field can become a quantitative science. The basic principle of NanoInteract is that given identical nanomaterials, cells and biological materials, and using a common protocol, experiments must yield identical answers. Thus, any deviations result from errors in (applying) the protocol which can be tracked and eliminated, until quantitatively reproducible results are obtained by any researcher in any location. This paper outlines the

NANOINTERACT: A rational approach to the interaction between nanoscale materials and living matter?

Science.gov (United States)

Lynch, Iseult; Linse, Sara; Vyvyan Howard, C.; Stepnik, Maciej; Rydzynski, Konrad; Hanrahan, John; de Jong, Wim; Langevin, Dominique; Rädler, Joachim; Parak, Wolfgang; Volkov, Yuri; Radomski, Marek; Thomas, Robert; Klein, Jacob; Barron, Andrew A.; Janssen, Colin; Lyons, Fiona M.; Quinn, Francis; Swennen, Bert; Cuypers, Peter; Duffy, Angela; Dawson, Kenneth A.

2009-05-01

The importance of understanding the interactions between nanoscale materials and living matter has now begun to be appreciated by an extraordinaryly large range of stakeholders, including researchers, industry, governments and society, all of whom appreciate both the opportunities presented by and challenges raised by this arena of research. Not only does it open up new directions in nanomedicine and nanodiagnostics, but it also offers the chance to implement nanotechnology across all industry in a safe and responsible manner. The underlying reasons for this arena as a new scientific paradigm are real and durable. Less than 100 nm nanoparticles can enter cells, less that 40 nm they can enter cell nucleus, and less that 35 nm they can pass through the blood brain barrier. These are fundamental length scales of biological relevance that will ensure that engineered nanoscience will impinge on biology and medicine for many decades to come. One important issue is the current lack of reproducibility of the outcomes of many experiments in this arena. Differences are likely a consequence of such things as uncontrolled nanoparticle aggregation leading to unpredictable doses being presented to cells, interference of the nanoparticles themselves with many of the tests being applied, differences in the degree of confluency of the cells used, and a host of other factors. NanoInteract has shown how careful control of all aspects of the test system, combined with round robin type approaches, can help resolve these issues and begin to ensure that the field can become a quantitative science. The basic principle of NanoInteract is that given identical nanomaterials, cells and biological materials, and using a common protocol, experiments must yield identical answers. Thus, any deviations result from errors in (applying) the protocol which can be tracked and eliminated, until quantitatively reproducible results are obtained by any researcher in any location. This paper outlines the

Nano-scale characterization of white layer in broached Inconel 718

Energy Technology Data Exchange (ETDEWEB)

Chen, Zhe, E-mail: zhe.chen@liu.se [Division of Engineering Materials, Linköping University, 58183 Linköping (Sweden); Colliander, Magnus Hörnqvist; Sundell, Gustav [Department of Physics, Chalmers University of Technology, 41296 Gothenburg (Sweden); Peng, Ru Lin [Division of Engineering Materials, Linköping University, 58183 Linköping (Sweden); Zhou, Jinming [Division of Production and Materials Engineering, Lund University, 22100 Lund (Sweden); Johansson, Sten; Moverare, Johan [Division of Engineering Materials, Linköping University, 58183 Linköping (Sweden)

2017-01-27

The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718. TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale.

Sb-Te Phase-change Materials under Nanoscale Confinement

Science.gov (United States)

Ihalawela, Chandrasiri A.

Size, speed and efficiency are the major challenges of next generation nonvolatile memory (NVM), and phase-change memory (PCM) has captured a great attention due to its promising features. The key for PCM is rapid and reversible switching between amorphous and crystalline phases with optical or electrical excitation. The structural transition is associated with significant contrast in material properties which can be utilized in optical (CD, DVD, BD) and electronic (PCRAM) memory applications. Importantly, both the functionality and the success of PCM technology significantly depend on the core material and its properties. So investigating PC materials is crucial for the development of PCM technology to realized enhanced solutions. In regards to PC materials, Sb-Te binary plays a significant role as a basis to the well-known Ge-Sb-Te system. Unlike the conventional deposition methods (sputtering, evaporation), electrochemical deposition method is used due to its multiple advantages, such as conformality, via filling capability, etc. First, the controllable synthesis of Sb-Te thin films was studied for a wide range of compositions using this novel deposition method. Secondly, the solid electrolytic nature of stoichiometric Sb2Te3 was studied with respect to precious metals. With the understanding of 2D thin film synthesis, Sb-Te 1D nanowires (18 - 220 nm) were synthesized using templated electrodeposition, where nanoporous anodic aluminum oxide (AAO) was used as a template for the growth of nanowires. In order to gain the controllability over the deposition in high aspect ratio structures, growth mechanisms of both the thin films and nanowires were investigated. Systematic understanding gained thorough previous studies helped to formulate the ultimate goal of this dissertation. In this dissertation, the main objective is to understand the size effect of PC materials on their phase transition properties. The reduction of effective memory cell size in conjunction with

Thermal control surfaces on the MSFC LDEF experiments

International Nuclear Information System (INIS)

Wilkes, D.R.; Whitaker, A.F.; Zwiener, J.M.; Linton, R.C.; Shular, D.; Peters, P.N.; Gregory, J.C.

1992-01-01

There were five Marshall Space Flight Center (MSFC) experiments on the LDEF. Each of those experiments carried thermal control surfaces either as test samples or as operational surfaces. These materials experienced varying degrees of mechanical and optical damage. Some materials were virtually unchanged by the extended exposure while others suffered extensive degradation. The synergistic effects due to the constituents of the space environment are evident in the diversity of these material changes. The sample complement for the MSFC experiments is described along with results of the continuing analyses efforts

Field limit and nano-scale surface topography of superconducting radio-frequency cavity made of extreme type II superconductor

Science.gov (United States)

Kubo, Takayuki

2015-06-01

The field limit of a superconducting radio-frequency cavity made of a type II superconductor with a large Ginzburg-Landau parameter is studied, taking the effects of nano-scale surface topography into account. If the surface is ideally flat, the field limit is imposed by the superheating field. On the surface of cavity, however, nano-defects almost continuously distribute and suppress the superheating field everywhere. The field limit is imposed by an effective superheating field given by the product of the superheating field for an ideal flat surface and a suppression factor that contains the effects of nano-defects. A nano-defect is modeled by a triangular groove with a depth smaller than the penetration depth. An analytical formula for the suppression factor of bulk and multilayer superconductors is derived in the framework of the London theory. As an immediate application, the suppression factor of the dirty Nb processed by electropolishing is evaluated by using results of surface topographic study. The estimated field limit is consistent with the present record field of nitrogen-doped Nb cavities. Suppression factors of surfaces of other bulk and multilayer superconductors, and those after various surface processing technologies, can also be evaluated by using the formula.

Dopant atoms as quantum components in silicon nanoscale devices

Science.gov (United States)

Zhao, Xiaosong; Han, Weihua; Wang, Hao; Ma, Liuhong; Li, Xiaoming; Zhang, Wang; Yan, Wei; Yang, Fuhua

2018-06-01

Recent progress in nanoscale fabrication allows many fundamental studies of the few dopant atoms in various semiconductor nanostructures. Since the size of nanoscale devices has touched the limit of the nature, a single dopant atom may dominate the performance of the device. Besides, the quantum computing considered as a future choice beyond Moore's law also utilizes dopant atoms as functional units. Therefore, the dopant atoms will play a significant role in the future novel nanoscale devices. This review focuses on the study of few dopant atoms as quantum components in silicon nanoscale device. The control of the number of dopant atoms and unique quantum transport characteristics induced by dopant atoms are presented. It can be predicted that the development of nanoelectronics based on dopant atoms will pave the way for new possibilities in quantum electronics. Project supported by National Key R&D Program of China (No. 2016YFA0200503).

Nanoscale thermoelectric materials

International Nuclear Information System (INIS)

Failamani, F.

2015-01-01

Thermoelectric (TE) materials directly convert thermal energy to electrical energy when subjected to a temperature gradient, whereas if electricity is applied to thermoelectric materials, a temperature gradient is formed. The performance of thermoelectric materials is characterized by a dimensionless figure of merit (ZT = S2T/ρλ), which consists of three parameters, Seebeck coefficient (S), electrical resistivity (ρ) and thermal conductivity (λ). To achieve good performance of thermoelectric power generation and cooling, ZT's of thermoelectric materials must be as high as possible, preferably above unity. This thesis comprises three main parts, which are distributed into six chapters: (i) nanostructuring to improve TE performance of trivalent rare earth-filled skutterudites (chapter 1 and 2), (ii) interactions of skutterudite thermolectrics with group V metals as potential electrode or diffusion barrier for TE devices (chapter 3 and 4), and (iii) search for new materials for TE application (chapter 5 and 6). Addition of secondary phases, especially nano sized phases can cause additional reduction of the thermal conductivity of a filled skutterudite which improves the figure of merit (ZT) of thermoelectric materials. In chapter 1 we investigated the effect of various types of secondary phases (silicides, borides, etc.) on the TE properties of trivalent rare earth filled Sb-based skutterudites as commercially potential TE materials. In this context the possibilty to introduce borides as nano-particles (via ball-milling in terms of a skutterudite/boride composite) is also elucidated in chapter 2. As a preliminary study, crystal structure of novel high temperature FeB-type phases found in the ternary Ta-{Ti,Zr,Hf,}-B systems were investigated. In case of Ti and Hf this phase is the high temperature stabilization of binary group IV metal monoborides, whereas single crystal study of (Ta,Zr)B proves that it is a true ternary phase as no stable monoboride exist in the

Modeling of nanoscale liquid mixture transport by density functional hydrodynamics

Science.gov (United States)

Dinariev, Oleg Yu.; Evseev, Nikolay V.

2017-06-01

Modeling of multiphase compositional hydrodynamics at nanoscale is performed by means of density functional hydrodynamics (DFH). DFH is the method based on density functional theory and continuum mechanics. This method has been developed by the authors over 20 years and used for modeling in various multiphase hydrodynamic applications. In this paper, DFH was further extended to encompass phenomena inherent in liquids at nanoscale. The new DFH extension is based on the introduction of external potentials for chemical components. These potentials are localized in the vicinity of solid surfaces and take account of the van der Waals forces. A set of numerical examples, including disjoining pressure, film precursors, anomalous rheology, liquid in contact with heterogeneous surface, capillary condensation, and forward and reverse osmosis, is presented to demonstrate modeling capabilities.

Nanoscale roughness contact in a slider-disk interface.

Science.gov (United States)

Hua, Wei; Liu, Bo; Yu, Shengkai; Zhou, Weidong

2009-07-15

The nanoscale roughness contact between molecularly smooth surfaces of a slider-disk interface in a hard disk drive is analyzed, and the lubricant behavior at very high shear rate is presented. A new contact model is developed to study the nanoscale roughness contact behavior by classifying various forms of contact into slider-lubricant contact, slider-disk elastic contact and plastic contact. The contact pressure and the contact probabilities of the three types of contact are investigated. The new contact model is employed to explain and provide insight to an interesting experimental result found in a thermal protrusion slider. The protrusion budget for head surfing in the lubricant, which is the ideal state for contact recording, is also discussed.

Nanoscale roughness contact in a slider-disk interface

International Nuclear Information System (INIS)

Hua Wei; Liu Bo; Yu Shengkai; Zhou Weidong

2009-01-01

The nanoscale roughness contact between molecularly smooth surfaces of a slider-disk interface in a hard disk drive is analyzed, and the lubricant behavior at very high shear rate is presented. A new contact model is developed to study the nanoscale roughness contact behavior by classifying various forms of contact into slider-lubricant contact, slider-disk elastic contact and plastic contact. The contact pressure and the contact probabilities of the three types of contact are investigated. The new contact model is employed to explain and provide insight to an interesting experimental result found in a thermal protrusion slider. The protrusion budget for head surfing in the lubricant, which is the ideal state for contact recording, is also discussed.

Nanoscale multiple gaseous layers on a hydrophobic surface.

Science.gov (United States)

Zhang, Lijuan; Zhang, Xuehua; Fan, Chunhai; Zhang, Yi; Hu, Jun

2009-08-18

The nanoscale gas state at the interfaces of liquids (water, acid, and salt solutions) and highly oriented pyrolytic graphite (HOPG) was investigated via tapping-mode atomic force microscopy (AFM). For the first time, we report that the interfacial gases could form bilayers and trilayers, i.e., on the top of a flat gas layer, there are one or two more gas layers. The formation of these gas layers could be induced by a local supersaturation of gases, which can be achieved by (1) temperature difference between the liquids and the HOPG substrates or (2) exchange ethanol with water. Furthermore, we found that the gas layers were less stable than spherical bubbles. They could transform to bubbles with time or under the perturbation of the AFM tip.

Nanoscale control of reversible chemical reaction between fullerene C60 molecules using scanning tunneling microscope.

Science.gov (United States)

Nakaya, Masato; Kuwahara, Yuji; Aono, Masakazu; Nakayama, Tomonobu

2011-04-01

The nanoscale control of reversible chemical reactions, the polymerization and depolymerization between C60 molecules, has been investigated. Using a scanning tunneling microscope (STM), the polymerization and depolymerization can be controlled at designated positions in ultrathin films of C60 molecules. One of the two chemical reactions can be selectively induced by controlling the sample bias voltage (V(s)); the application of negative and positive values of V(s) results in polymerization and depolymerization, respectively. The selectivity between the two chemical reactions becomes extremely high when the thickness of the C60 film increases to more than three molecular layers. We conclude that STM-induced negative and positive electrostatic ionization are responsible for the control of the polymerization and depolymerization, respectively.

Facilitation of Nanoscale Thermal Transport by Hydrogen Bonds

OpenAIRE

Zhang, Lin

2017-01-01

Thermal transport performance at the nanoscale and/or of biomaterials is essential to the success of many new technologies including nanoelectronics, biomedical devices, and various nanocomposites. Due to complicated microstructures and chemical bonding, thermal transport process in these materials has not been well understood yet. In terms of chemical bonding, it is well known that the strength of atomic bonding can significantly affect thermal transport across materials or across interfaces...

Surface morphology effects on the light-controlled wettability of ZnO nanostructures

Energy Technology Data Exchange (ETDEWEB)

Khranovskyy, V., E-mail: volkh@ifm.liu.se [Department of Physics, Chemistry and Biology (IFM), Linkoping University (Sweden); Ekblad, T.; Yakimova, R.; Hultman, L. [Department of Physics, Chemistry and Biology (IFM), Linkoping University (Sweden)

2012-08-01

ZnO nanostructures of diverse morphology with shapes of corrals and cabbages as well as open and filled hexagons and sheaves prepared by APMOCVD technique, are investigated with water contact angle (CA) analysis. The as-grown ZnO nanostructures exhibit pure hydrophobic behavior, which is enhanced with the increase of the nanostructure's surface area. The most hydrophobic structures (CA = 124 Degree-Sign ) were found to be the complex nanosheaf, containing both the macro-and nanoscale features. It is concluded that the nanoscale roughness contributes significantly to the hydrophobicity increase. The character of wettability was possible to switch from hydrophobic-to-superhydrophilic state upon ultra violet irradiation. Both the rate and amplitude of the contact angle depend on the characteristic size of nanostructure. The observed effect is explained due to the semiconductor properties of zinc oxide enhanced by increased surface chemistry effect in nanostructures.

Nanoscale mechanical stimulation method for quantifying C. elegans mechanosensory behavior and memory

OpenAIRE

Kiso, Kaori; Sugi, Takuma; Okumura, Etsuko; Igarashi, Ryuji

2016-01-01

Here, we establish a novel economic system to quantify C. elegans mechanosensory behavior and memory by a controllable nanoscale mechanical stimulation. Using piezoelectric sheet speaker, we can flexibly change the vibration properties at a nanoscale displacement level and quantify behavioral responses and memory under the control of each vibration property. This system will facilitate understanding of physiological aspects of C. elegans mechanosensory behavior and memory.

The Functionalization, Size Control and Properties of Metal-Organic Frameworks

DEFF Research Database (Denmark)

Xu, Hui; Iversen, Bo Brummerstedt

Recent years, Metal-Organic Framework (MOF) materials have drawn great attentions due to their potential applications in gas sorption/separation and luminescent sensing. In this dissertation, the recent progress of MOF materials is reviewed, with specific focus on the functionalization, size....... A nanoscale MOF material with controllable size was realized whose morphology has been simulated base on the BFDH method, and the sensing of bacteria endospores was research in detail. We also report the synthesis and sensing of nitroaromatic explosives of a nanoscale MOF material....

Nanofluidics: A New Arena for Materials Science.

Science.gov (United States)

Xu, Yan

2018-01-01

A significant growth of research in nanofluidics is achieved over the past decade, but the field is still facing considerable challenges toward the transition from the current physics-centered stage to the next application-oriented stage. Many of these challenges are associated with materials science, so the field of nanofluidics offers great opportunities for materials scientists to exploit. In addition, the use of unusual effects and ultrasmall confined spaces of well-defined nanofluidic environments would offer new mechanisms and technologies to manipulate nanoscale objects as well as to synthesize novel nanomaterials in the liquid phase. Therefore, nanofluidics will be a new arena for materials science. In the past few years, burgeoning progress has been made toward this trend, as overviewed in this article, including materials and methods for fabricating nanofluidic devices, nanofluidics with functionalized surfaces and functional material components, as well as nanofluidics for manipulating nanoscale materials and fabricating new nanomaterials. Many critical challenges as well as fantastic opportunities in this arena lie ahead. Some of those, which are of particular interest, are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Static electric field enhancement in nanoscale structures

Energy Technology Data Exchange (ETDEWEB)

Lepetit, Bruno, E-mail: bruno.lepetit@irsamc.ups-tlse.fr; Lemoine, Didier, E-mail: didier.lemoine@irsamc.ups-tlse.fr [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Márquez-Mijares, Maykel, E-mail: mmarquez@instec.cu [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Instituto Superior de Tecnologías y Ciencias Aplicadas, Avenida Salvador Allende 1110, Quinta de los Molinos, La Habana (Cuba)

2016-08-28

We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.

Reduced wear of enamel with novel fine and nano-scale leucite glass-ceramics.

Science.gov (United States)

Theocharopoulos, Antonios; Chen, Xiaohui; Hill, Robert; Cattell, Michael J

2013-06-01

Leucite glass-ceramics used to produce all-ceramic restorations can suffer from brittle fracture and wear the opposing teeth. High strength and fine crystal sized leucite glass-ceramics have recently been reported. The objective of this study is to investigate whether fine and nano-scale leucite glass-ceramics with minimal matrix microcracking are associated with a reduction in in vitro tooth wear. Human molar cusps (n=12) were wear tested using a Bionix-858 testing machine (300,000 simulated masticatory cycles) against experimental fine crystal sized (FS), nano-scale crystal sized (NS) leucite glass-ceramics and a commercial leucite glass-ceramic (Ceramco-3, Dentsply, USA). Wear was imaged using Secondary Electron Imaging (SEI) and quantified using white-light profilometry. Both experimental groups were found to produce significantly (pceramic) loss than the FS group. Increased waviness and damage was observed on the wear surfaces of the Ceramco-3 glass-ceramic disc/tooth group in comparison to the experimental groups. This was also indicated by higher surface roughness values for the Ceramco-3 glass-ceramic disc/tooth group. Fine and nano-sized leucite glass-ceramics produced a reduction in in vitro tooth wear. The high strength low wear materials of this study may help address the many problems associated with tooth enamel wear and restoration failure. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

Science.gov (United States)

Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

2015-12-01

The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites. Here we show for a bifunctional catalyst—comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder—that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil, should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.

Zwitterionic materials for antifouling membrane surface construction.

Science.gov (United States)

He, Mingrui; Gao, Kang; Zhou, Linjie; Jiao, Zhiwei; Wu, Mengyuan; Cao, Jialin; You, Xinda; Cai, Ziyi; Su, Yanlei; Jiang, Zhongyi

2016-08-01

Membrane separation processes are often perplexed by severe and ubiquitous membrane fouling. Zwitterionic materials, keeping electric neutrality with equivalent positive and negative charged groups, are well known for their superior antifouling properties and have been broadly utilized to construct antifouling surfaces for medical devices, biosensors and marine coatings applications. In recent years, zwitterionic materials have been more and more frequently utilized for constructing antifouling membrane surfaces. In this review, the antifouling mechanisms of zwitterionic materials as well as their biomimetic prototypes in cell membranes will be discussed, followed by the survey of common approaches to incorporate zwitterionic materials onto membrane surfaces including surface grafting, surface segregation, biomimetic adhesion, surface coating and so on. The potential applications of these antifouling membranes are also embedded. Finally, we will present a brief perspective on the future development of zwitterionic materials modified antifouling membranes. Membrane fouling is a severe problem hampering the application of membrane separation technology. The properties of membrane surfaces play a critical role in membrane fouling and antifouling behavior/performance. Antifouling membrane surface construction has evolved as a hot research issue for the development of membrane processes. Zwitterionic modification of membrane surfaces has been recognized as an effective strategy to resist membrane fouling. This review summarizes the antifouling mechanisms of zwitterionic materials inspired by cell membranes as well as the popular approaches to incorporate them onto membrane surfaces. It can help form a comprehensive knowledge about the principles and methods of modifying membrane surfaces with zwitterionic materials. Finally, we propose the possible future research directions of zwitterionic materials modified antifouling membranes. Copyright © 2016 Acta Materialia Inc

Near-surface processing on AlGaN/GaN heterostructures: a nanoscale electrical and structural characterization

Directory of Open Access Journals (Sweden)

Greco Giuseppe

2011-01-01

Full Text Available Abstract The effects of near-surface processing on the properties of AlGaN/GaN heterostructures were studied, combining conventional electrical characterization on high-electron mobility transistors (HEMTs, with advanced characterization techniques with nanometer scale resolution, i.e., transmission electron microscopy, atomic force microscopy (AFM and conductive atomic force microscopy (C-AFM. In particular, a CHF3-based plasma process in the gate region resulted in a shift of the threshold voltage in HEMT devices towards less negative values. Two-dimensional current maps acquired by C-AFM on the sample surface allowed us to monitor the local electrical modifications induced by the plasma fluorine incorporated in the material. The results are compared with a recently introduced gate control processing: the local rapid thermal oxidation process of the AlGaN layer. By this process, a controlled thin oxide layer on surface of AlGaN can be reliably introduced while the resistance of the layer below increase locally.

Near-surface processing on AlGaN/GaN heterostructures: a nanoscale electrical and structural characterization.

Science.gov (United States)

Greco, Giuseppe; Giannazzo, Filippo; Frazzetto, Alessia; Raineri, Vito; Roccaforte, Fabrizio

2011-02-11

The effects of near-surface processing on the properties of AlGaN/GaN heterostructures were studied, combining conventional electrical characterization on high-electron mobility transistors (HEMTs), with advanced characterization techniques with nanometer scale resolution, i.e., transmission electron microscopy, atomic force microscopy (AFM) and conductive atomic force microscopy (C-AFM). In particular, a CHF3-based plasma process in the gate region resulted in a shift of the threshold voltage in HEMT devices towards less negative values. Two-dimensional current maps acquired by C-AFM on the sample surface allowed us to monitor the local electrical modifications induced by the plasma fluorine incorporated in the material.The results are compared with a recently introduced gate control processing: the local rapid thermal oxidation process of the AlGaN layer. By this process, a controlled thin oxide layer on surface of AlGaN can be reliably introduced while the resistance of the layer below increase locally.

The nanoscale organization of the B lymphocyte membrane☆

Science.gov (United States)

Maity, Palash Chandra; Yang, Jianying; Klaesener, Kathrin; Reth, Michael

2015-01-01

The fluid mosaic model of Singer and Nicolson correctly predicted that the plasma membrane (PM) forms a lipid bi-layer containing many integral trans-membrane proteins. This model also suggested that most of these proteins were randomly dispersed and freely diffusing moieties. Initially, this view of a dynamic and rather unorganized membrane was supported by early observations of the cell surfaces using the light microscope. However, recent studies on the PM below the diffraction limit of visible light (~ 250 nm) revealed that, at nanoscale dimensions, membranes are highly organized and compartmentalized structures. Lymphocytes are particularly useful to study this nanoscale membrane organization because they grow as single cells and are not permanently engaged in cell:cell contacts within a tissue that can influence membrane organization. In this review, we describe the methods that can be used to better study the protein:protein interaction and nanoscale organization of lymphocyte membrane proteins, with a focus on the B cell antigen receptor (BCR). Furthermore, we discuss the factors that may generate and maintain these membrane structures. PMID:25450974

On the influence of surface patterning on tissue self-assembly and mechanics.

Science.gov (United States)

Coppola, Valerio; Ventre, Maurizio; Natale, Carlo F; Rescigno, Francesca; Netti, Paolo A

2018-04-28

Extracellular matrix assembly and composition influence the biological and mechanical functions of tissues. Developing strategies to control the spatial arrangement of cells and matrix is of central importance for tissue engineering-related approaches relying on self-assembling and scaffoldless processes. Literature reports demonstrated that signals patterned on material surfaces are able to control cell positioning and matrix orientation. However, the mechanisms underlying the interactions between material signals and the structure of the de novo synthesized matrix are far from being thoroughly understood. In this work, we investigated the ordering effect provided by nanoscale topographic patterns on the assembly of tissue sheets grown in vitro. We stimulated MC3T3-E1 preosteoblasts to produce and assemble a collagen-rich matrix on substrates displaying patterns with long- or short-range order. Then, we investigated microstructural features and mechanical properties of the tissue in uniaxial tension. Our results demonstrate that patterned material surfaces are able to control the initial organization of cells in close contact to the surface; then cell-generated contractile forces profoundly remodel tissue structure towards mechanically stable spatial patterns. Such a remodelling effect acts both locally, as it affects cell and nuclear shape and globally, by affecting the gross mechanical response of the tissue. Such an aspect of dynamic interplay between cells and the surrounding matrix must be taken into account when designing material platform for the in vitro generation of tissue with specific microstructural assemblies. Copyright © 2018 John Wiley & Sons, Ltd.

Computational design of surfaces, nanostructures and optoelectronic materials

Science.gov (United States)

Choudhary, Kamal

Properties of engineering materials are generally influenced by defects such as point defects (vacancies, interstitials, substitutional defects), line defects (dislocations), planar defects (grain boundaries, free surfaces/nanostructures, interfaces, stacking faults) and volume defects (voids). Classical physics based molecular dynamics and quantum physics based density functional theory can be useful in designing materials with controlled defect properties. In this thesis, empirical potential based molecular dynamics was used to study the surface modification of polymers due to energetic polyatomic ion, thermodynamics and mechanics of metal-ceramic interfaces and nanostructures, while density functional theory was used to screen substituents in optoelectronic materials. Firstly, polyatomic ion-beams were deposited on polymer surfaces and the resulting chemical modifications of the surface were examined. In particular, S, SC and SH were deposited on amorphous polystyrene (PS), and C2H, CH3, and C3H5 were deposited on amorphous poly (methyl methacrylate) (PMMA) using molecular dynamics simulations with classical reactive empirical many-body (REBO) potentials. The objective of this work was to elucidate the mechanisms by which the polymer surface modification took place. The results of the work could be used in tailoring the incident energy and/or constituents of ion beam for obtaining a particular chemistry inside the polymer surface. Secondly, a new Al-O-N empirical potential was developed within the charge optimized many body (COMB) formalism. This potential was then used to examine the thermodynamic stability of interfaces and mechanical properties of nanostructures composed of aluminum, its oxide and its nitride. The potentials were tested for these materials based on surface energies, defect energies, bulk phase stability, the mechanical properties of the most stable bulk phase, its phonon properties as well as with a genetic algorithm based evolution theory of

Photomobile polymer materials towards eight driven plastic motors

International Nuclear Information System (INIS)

Tomi Ikeda

2007-01-01

We present the first report of working photomechanical devices, and simple plastic motors, driven only by light. The size scale of the energy transduction systems here is mm for demonstration, but is not principle material-limited, so numerous applications on the nano-scale are possible where efficient power supply to mechanical systems is battery-free and non-contact. The photomobile polymers function with a minimum of moving parts which minimizes the friction and surface contact difficulties on the small scale, and one can further envisage applications as direct solar-to-mechanical energy conversion and storage systems, and use in devices requiring through-space power transmission such as microfluidic device control, bio-interfaces, or other remote power supply. (Author)

Feasibility Study of Nanoscale Semiconductor Manufacture Using Thermal Dip Pen Nanolithography

National Research Council Canada - National Science Library

King, William P

2006-01-01

...) for the purpose of nanoscale electronics manufacturing. In this project, we have demonstrated that using the thermal DPN technique that both indium metal, and semiconducting organic materials (PDDT, PVDF...

The development of the American national standard, ''control of radioactive surface contamination on materials, equipment and facilities to be released for uncontrolled use''

International Nuclear Information System (INIS)

Shapiro, J.

1980-01-01

The American National Standard, Control of Radioactive Surface Contamination on Materials, Equipment and Facilities to be Released for Uncontrolled Use, was developed under the procedures of ANSI for ANSI Main Committee N13 (Radiation Protection) by a working group of the Health Physics Society Standards Committee. This standard provides criteria for the control of materials, equipment and facilities contaminated with radioactivity proposed to be released for uncontrolled use. Permissible contamination limits are specified as well as methods assessing the levels of contamination. This paper reviews the proceedings of the Subcommittee on Radioactive Surface Contamination, the comments received by reviewers of the standard, the resolution of the committee, and the bases for reaching the final limits, recommendations, and measurement procedures. (H.K.)

Suitability of dredged material for reclamation of surface-mined land. Final report

Energy Technology Data Exchange (ETDEWEB)

Harrison, W.; Van Luik, A.

1979-12-01

Eroding ridges of acidic coal-mine spoil in La Salle County, Illinois, were leveled to form a gently-sloped raised plateau. Four test plots were constructed: a control plot and three treatment plots that received a 0.9-m-thick cover of dredged material obtained from the Metropolitan Sanitary District of Greater Chicago. Two treatment plots received lime applications and all plots were seeded with a mixture of grasses. Pressure-vacuum soil water samplers were installed, in duplicate, at two levels in the control plot and at three levels in each treatment plot. The three levels in the treatment plots coincided with dredged material, the dredged-material mine-spoil interface, and the underlying mine spoil. Surface water, soil water, and groundwater were monitored for 29 water-quality parameters for one year. Rainfall, air temperature, runoff, and water-level elevation data were collected also. Detailed analysis of the data indicates that the dredged material used in this study does not adversely affect water quality; it supports abundant plant growth, lessens groundwater contamination, and controls acid runoff. The dredged material is judged to be a suitable material for use in reclamation of surface-mined land.

Computer design of porous active materials at different dimensional scales

Science.gov (United States)

Nasedkin, Andrey

2017-12-01

The paper presents a mathematical and computer modeling of effective properties of porous piezoelectric materials of three types: with ordinary porosity, with metallized pore surfaces, and with nanoscale porosity structure. The described integrated approach includes the effective moduli method of composite mechanics, simulation of representative volumes, and finite element method.

Fourth International Conference on Nanoscale Magnetism

CERN Document Server

Aktas, Bekir; Advances in Nanoscale Magnetism

2009-01-01

The book aims to provide an overview of recent progress in the understanding of magnetic properties in nanoscale through recent results of various theoretical and experimental investigations. The papers describe a wide range of physical aspects, together with theoretical and experimental methods. It is of central interest to researchers and specialists in magnetism and magnetic materials science, both in academic and industrial research, as well as advanced students.

Bioinspired Functional Surfaces for Technological Applications

Science.gov (United States)

Sharma, Vipul; Kumar, Suneel; Reddy, Kumbam Lingeshwar; Bahuguna, Ashish; Krishnan, Venkata

2016-08-01

Biological matters have been in continuous encounter with extreme environmental conditions leading to their evolution over millions of years. The fittest have survived through continuous evolution, an ongoing process. Biological surfaces are the important active interfaces between biological matters and the environment, and have been evolving over time to a higher state of intelligent functionality. Bioinspired surfaces with special functionalities have grabbed attention in materials research in the recent times. The microstructures and mechanisms behind these functional biological surfaces with interesting properties have inspired scientists to create artificial materials and surfaces which possess the properties equivalent to their counterparts. In this review, we have described the interplay between unique multiscale (micro- and nano-scale) structures of biological surfaces with intrinsic material properties which have inspired researchers to achieve the desired wettability and functionalities. Inspired by naturally occurring surfaces, researchers have designed and fabricated novel interfacial materials with versatile functionalities and wettability, such as superantiwetting surfaces (superhydrophobic and superoleophobic), omniphobic, switching wettability and water collecting surfaces. These strategies collectively enable functional surfaces to be utilized in different applications such as fog harvesting, surface-enhanced Raman spectroscopy (SERS), catalysis, sensing and biological applications. This paper delivers a critical review of such inspiring biological surfaces and artificial bioinspired surfaces utilized in different applications, where material science and engineering have merged by taking inspiration from the natural systems.

Advances in Surface Plasmon Resonance Imaging enable quantitative measurement of laterally heterogeneous coatings of nanoscale thickness

Science.gov (United States)

Raegen, Adam; Reiter, Kyle; Clarke, Anthony; Lipkowski, Jacek; Dutcher, John

2013-03-01

The Surface Plasmon Resonance (SPR) phenomenon is routinely exploited to qualitatively probe changes to the optical properties of nanoscale coatings on thin metallic surfaces, for use in probes and sensors. Unfortunately, extracting truly quantitative information is usually limited to a select few cases - uniform absorption/desorption of small biomolecules and films, in which a continuous ``slab'' model is a good approximation. We present advancements in the SPR technique that expand the number of cases for which the technique can provide meaningful results. Use of a custom, angle-scanning SPR imaging system, together with a refined data analysis method, allow for quantitative kinetic measurements of laterally heterogeneous systems. We first demonstrate the directionally heterogeneous nature of the SPR phenomenon using a directionally ordered sample, then show how this allows for the calculation of the average coverage of a heterogeneous sample. Finally, the degradation of cellulose microfibrils and bundles of microfibrils due to the action of cellulolytic enzymes will be presented as an excellent example of the capabilities of the SPR imaging system.

Light-responsive smart surface with controllable wettability and excellent stability.

Science.gov (United States)

Zhou, Yin-Ning; Li, Jin-Jin; Zhang, Qing; Luo, Zheng-Hong

2014-10-21

Novel fluorinated gradient copolymer was designed for smart surface with light-responsive controllable wettability and excellent stability. The switchable mechanism and physicochemical characteristics of the as-prepared surface decorated by designed polymeric material were investigated by ultraviolet-visible (UV-vis) spectrum, scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). Thanks to the functional film and surface roughening, etched silicon surface fabricated by copolymer involving spiropyran (Sp) moieties possesses a fairly large variation range of WCA (28.1°) and achieves the transformation between hydrophilicity (95.2° 109.2°) relative to blank sample (109.2°). The synthetic strategy and developed smart surface offer a promising application in coating with controllable wettability, which bridge the gap between chemical structure and material properties.

Nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys

Energy Technology Data Exchange (ETDEWEB)

Tashlykova-Bushkevich, Iya I. [Belarusian State University of Informatics and Radioelectronics, Minsk (Belarus)

2015-12-31

The present work summarizes recent progress in the investigation of nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys foils produced at exceptionally high cooling rates. We focus here on the potential of modification of hydrogen desorption kinetics in respect to weak and strong trapping sites that could serve as hydrogen sinks in Al materials. It is shown that it is important to elucidate the surface microstructure of the Al alloy foils at the submicrometer scale because rapidly solidified microstructural features affect hydrogen trapping at nanostructured defects. We discuss the profound influence of solute atoms on hydrogen−lattice defect interactions in the alloys. with emphasis on role of vacancies in hydrogen evolution; both rapidly solidified pure Al and conventionally processed aluminum samples are considered.

Nanoscale luminescent lanthanide-based metal–organic frameworks: properties, synthesis, and applications

Energy Technology Data Exchange (ETDEWEB)

Hu, Dongqin; Song, Yonghai; Wang, Li, E-mail: lwanggroup@aliyun.com [Jiangxi Normal University, Key Laboratory of Functional Small Organic Molecule, Ministry of Education, Key Laboratory of Chemical Biology, Jiangxi Province, College of Chemistry and Chemical Engineering (China)

2015-07-15

Nanoscale luminescent lanthanide-based metal–organic frameworks (NLLn-MOFs) possess superior optical and physical properties such as higher luminescent lifetime, quantum yield, high stability, high surface area, high agent loading, and intrinsic biodegradability, and therefore are regarded as a novel generation of luminescent material compared with bulk lanthanide-based metal–organic frameworks (Ln-MOFs). Traditional luminescent Ln-MOFs have been well studied; however, NLLn-MOFs taking the advantages of nanomaterials have attracted extensive investigations for applications in optical imaging in living cells, light-harvesting, and sensing. In this review, we provide a survey of the latest progresses made in developing NLLn-MOFs, which contains the fundamental optical features, synthesis, and their potential applications. Finally, the future prospects and challenges of the rapidly growing field are summarized.

Basic reactions of osteoblasts on structured material surfaces

Directory of Open Access Journals (Sweden)

U. Meyer

2005-04-01

Full Text Available In order to assess how bone substitute materials determine bone formation in vivo it is useful to understand the mechanisms of the material surface/tissue interaction on a cellular level. Artificial materials are used in two applications, as biomaterials alone or as a scaffold for osteoblasts in a tissue engineering approach. Recently, many efforts have been undertaken to improve bone regeneration by the use of structured material surfaces. In vitro studies of bone cell responses to artificial materials are the basic tool to determine these interactions. Surface properties of materials surfaces as well as biophysical constraints at the biomaterial surface are of major importance since these features will direct the cell responses. Studies on osteoblast-like cell reactivity towards materials will have to focus on the different steps of protein and cell reactions towards defined surface properties. The introduction of new techniques allows nowadays the fabrication of materials with ordered surface structures. This paper gives a review of present knowledge on the various stages of osteoblast reactions on material surfaces, focused on basic cell events under in vitro conditions. Special emphasis is given to cellular reactions towards ordered nano-sized topographies.