WorldWideScience

Sample records for nano-scale material structure

  1. STRUCTURE AND DYNAMICS OF POLYMERIC MATERIALS IN NANO-SCALE

    Institute of Scientific and Technical Information of China (English)

    Toshio Nishi; So Fujinami; Dong Wang; Hao Liu; Ken Nakajima

    2011-01-01

    The nano-palpation technique, i.e., nanometer-scale elastic and viscoelastic measurements based on atomic force microscope, is introduced. It is demonstrated to be very useful in analyzing nanometer-scale materials properties for the surfaces and interfaces of various types of soft materials. It enables us to obtain not only structural information but also mechanical information about a material at the same place and at the same time.

  2. Ultrafast Laser Pulses for Structuring Materials at Micro/Nano Scale: From Waveguides to Superhydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Daniel S. Correa

    2017-01-01

    Full Text Available The current demand for fabricating optical and photonic devices displaying high performance, using low-cost and time-saving methods, prompts femtosecond (fs-laser processing as a promising methodology. High and low repetition femtosecond lasers enable surface and/or bulk modification of distinct materials, which can be used for applications ranging from optical waveguides to superhydrophobic surfaces. Herein, some fundamental aspects of fs-laser processing of materials, as well as the basics of their most common experimental apparatuses, are introduced. A survey of results on polymer fs-laser processing, resulting in 3D waveguides, electroluminescent structures and active hybrid-microstructures for luminescence or biological microenvironments is presented. Similarly, results of fs-laser processing on glasses, gold and silicon to produce waveguides containing metallic nanoparticles, analytical chemical sensors and surface with modified features, respectively, are also described. The complexity of fs-laser micromachining involves precise control of material properties, pushing ultrafast laser processing as an advanced technique for micro/nano devices.

  3. Monolithic silica aerogel - material design on the nano-scale

    DEFF Research Database (Denmark)

    Jensen, Karsten Ingerslev; Schultz, Jørgen Munthe; Kristiansen, Finn Harken

    By means of a production process in two major steps - a sol/gel process and a supercritical drying – open-cell, monolithic silica aerogel can be made. This material can have a density in the range of 30- to 300 kg/m3, corresponding to porosities between 86 and 98 %. The solid structure has...... of piezoelectric transducers. - Other applications could be; waste encapsulation, spacers for vacuum insulation panels, membranes, etc. Department of Civil Engineering is co-ordinator of a current EU FP5 research project1, which deals with the application of aerogel as transparent insulation materials in windows....... Due to the excellent optical and thermal properties of aerogel, it is possible to develop windows with both high insulation and high transmittance, which is impossible applying the conventional window techniques, i.e. extra layers of glass, low-e coatings and gas fillings. It can be shown...

  4. Nano-scale spinning detonation in condensed phase energetic materials

    Science.gov (United States)

    Zhakhovsky, Vasily; Budzevich, Mikalai; Landerville, Aaron; White, Carter; Oleynik, Ivan

    2013-06-01

    Single- and multi-headed spinning detonation waves are observed in molecular dynamics simulations of a condensed phase detonation of an energetic material (EM) confined in round tubes of different radii. The EM is modeled using a modified AB Reactive Empirical Bond Order potential. The thermochemistry and reactive equation of state are varied by adjusting the barrier height for the exothermic reaction AB +B --> A +BB. This allows us to study the evolution of the detonation-wave structure as a function of physico-chemical properties of the AB explosive. The detonation wave is found to exhibit a pulsating planar front in a tube of 8 nm radius, which later collapses due to the development of longitudinal perturbations. Upon increase of the tube's radius to 16 nm, the detonation wave structure is stabilized through the development of a single-headed spinning detonation. The spinning detonation displays a four-wave configuration, including incident, oblique, transverse, and contact shock waves. The contact shock generated by a contact discontinuity is observed for the first time in our MD simulations. A multi-headed turbulent-like detonation structure develops within tubes of larger radii, and exhibit features similar to those observed in gases.

  5. Micro to Nano Scale Heat Conduction in Thermoelectric Materials

    Science.gov (United States)

    Maldovan, Martin

    2011-03-01

    Understanding and controlling heat transfer in solids is very important for increasing the efficiency of thermoelectric materials such as skutterudites, clatharates, superlattices, nanowires, and quantum dots. Although the mechanisms governing the thermal conductivity have been understood for years, a comprehensive theoretical method to calculate heat transfer, particularly at small scales, has not been available. This is mainly due to the complexity of anharmonic processes and phonon boundary scattering. We present a comprehensive theoretical model to calculate the thermal conductivity of thermoelectric materials at small length scales. The approach involves an exact calculation of the reduction of the phonon mean free paths due to boundary scattering and removes the need to solve the Boltzmann equation or to use adjustable terms as in the Callaway or Holland models. The analysis is based on the kinetic theory of transport processes and considers general expressions for dispersion relations, phonon mean free paths, and surface specularity parameters. The results show an excellent agreement with experiments for thin films, nanowires, and superlattices over a wide range of temperature and across multiple length scales. The theoretical approach can further be applied to a wide variety of problems involving the conduction of heat in micro/nanostructured thermoelectrics. This research was funded by the MIT Energy Initiative.

  6. Mechanical properties of materials at micro/nano scales

    Science.gov (United States)

    Xu, Wei-Hua

    Mechanical properties of materials in small dimensions, including the depth-dependent hardness at the nano/micrometer scales, and the mechanical characterization of thin films and nanotubes, are reported. The surface effect on the depth-dependent nano/microhardness was studied and an apparent surface stress was introduced to represent the energy dissipated per unit area of a solid surface. A plastic bearing ratio model was proposed for the nanoindentation of rough surfaces. The energy dissipation occurring at the indented surface is among the factors that cause the Indentation Size Effect (ISE) at the micro/nanometer scales. Furthermore, an elastic-plastic bearing ratio model was developed for nanoindentation of rough surfaces with a flat indenter tip. The theoretical predictions agree with the experimental results and finite element simulations, from which the elastic constant and the surface hardness were extracted. The surface hardness exhibits an inverse ISE due to the interaction of asperities. The nanoindentation tests on Highly Oriented Pyrolytic Graphite (HOPG) may lead to the formation of carbon tubes, which are rolled up by the delaminated graphite layers. The nanoindentation loading-unloading curves reveal single pop-in and multiple pop-in phenomena, which is induced by fracture of the graphite layers and/or by delamination between the layers. From the load at pop-in, the fracture strength of the layers and/or the bonding strength between the layers can be estimated by the elastic field model for Hertzian contact including sliding friction for transverse isotropy. Two novel methods were developed to estimate the mechanical properties of films, including the Raman spectra method for the estimation of residual stresses in thin ferroelectric films and the microbridge testing method for the mechanical characterization of trilayer thin films. Mechanical characterization was also carried out on Tobacco Mosaic Virus (TMV) nanotubes with each being comprised of

  7. Relationship between nano-scale deformation of coal structure and metamorphic-deformed environments

    Institute of Scientific and Technical Information of China (English)

    JU Yiwen; JIANG Bo; HOU Quanlin; WANG Guiliang

    2005-01-01

    There is a more consanguineous relation between nano-scale deformation of coal structure and metamorphic-deformed environment. In different metamorphic-deformed environments, deformation in the coal structure can occur not only at micro-scale, but also at nano-scale, and even leads to the change of molecular structure and nano-scale pore (<100 nm) structure. The latter is the main space absorbing coalbed methane. Through X-ray diffraction (XRD) and liquid-nitrogen absorption methods, the characteristics of macromolecular and nano-scale pore structures of coals in different metamorphic-deformed environments and deformational series of coals have been studied. By combining with high-resolution transmission electron microcopy (HRTEM), the macromolecular and nano-scale pore structures are also directly observed. These results demonstrate that the stacking Lc of the macromolecular BSU in tectonic coals increases quickly from the metamorphic-deformed environment of low rank coals to that of high rank coals. For different deformed tectonic coals, in the same metamorphic-deformed environment, the difference of Lc is obvious. These changes reflect chiefly the difference of different temperature and stress effect of nano-scale deformation in tectonic coals. The factor of temperature plays a greater role in the increase of macromolecular structure parameters Lc, the influence of stress factor is also important. With the stress strengthening, Lc shows an increasing trend, and La /Lc shows a decreasing trend. Therefore, Lc and La /Lc can be used as the indicator of nano-scale deformation degree of tectonic coals. With increasing temperature and pressure, especially oriented stress, the orientation of molecular structure becomes stronger, and ordering degree of C-nets and the arrangement of BSU are obviously enhanced. For the deformation of nano-scale pore structure, in the same metamorphic-deformed environment, along with the strengthening of stress, the ratio of mesopores to

  8. In situ thermomechanical testing methods for micro/nano-scale materials.

    Science.gov (United States)

    Kang, Wonmo; Merrill, Marriner; Wheeler, Jeffrey M

    2017-02-23

    The advance of micro/nanotechnology in energy-harvesting, micropower, electronic devices, and transducers for automobile and aerospace applications has led to the need for accurate thermomechanical characterization of micro/nano-scale materials to ensure their reliability and performance. This persistent need has driven various efforts to develop innovative experimental techniques that overcome the critical challenges associated with precise mechanical and thermal control of micro/nano-scale specimens during material characterization. Here we review recent progress in the development of thermomechanical testing methods from miniaturized versions of conventional macroscopic test systems to the current state of the art of in situ uniaxial testing capabilities in electron microscopes utilizing either indentation-based microcompression or integrated microsystems. We discuss the major advantages/disadvantages of these methods with respect to specimen size, range of temperature control, ease of experimentation and resolution of the measurements. We also identify key challenges in each method. Finally, we summarize some of the important discoveries that have been made using in situ thermomechanical testing and the exciting research opportunities still to come in micro/nano-scale materials.

  9. Structure-mechanical function relations at nano-scale in heat-affected human dental tissue.

    Science.gov (United States)

    Sui, Tan; Sandholzer, Michael A; Le Bourhis, Eric; Baimpas, Nikolaos; Landini, Gabriel; Korsunsky, Alexander M

    2014-04-01

    The knowledge of the mechanical properties of dental materials related to their hierarchical structure is essential for understanding and predicting the effect of microstructural alterations on the performance of dental tissues in the context of forensic and archaeological investigation as well as laser irradiation treatment of caries. So far, few studies have focused on the nano-scale structure-mechanical function relations of human teeth altered by chemical or thermal treatment. The response of dental tissues to thermal treatment is thought to be strongly affected by the mineral crystallite size, their spatial arrangement and preferred orientation. In this study, synchrotron-based small and wide angle X-ray scattering (SAXS/WAXS) techniques were used to investigate the micro-structural alterations (mean crystalline thickness, crystal perfection and degree of alignment) of heat-affected dentine and enamel in human dental teeth. Additionally, nanoindentation mapping was applied to detect the spatial and temperature-dependent nano-mechanical properties variation. The SAXS/WAXS results revealed that the mean crystalline thickness distribution in dentine was more uniform compared with that in enamel. Although in general the mean crystalline thickness increased both in dentine and enamel as the temperature increased, the local structural variations gradually reduced. Meanwhile, the hardness and reduced modulus in enamel decreased as the temperature increased, while for dentine, the tendency reversed at high temperature. The analysis of the correlation between the ultrastructure and mechanical properties coupled with the effect of temperature demonstrates the effect of mean thickness and orientation on the local variation of mechanical property. This structural-mechanical property alteration is likely to be due to changes of HAp crystallites, thus dentine and enamel exhibit different responses at different temperatures. Our results enable an improved understanding of

  10. Nano-scale Interfacial Friction Behavior between Two Kinds of Materials in MEMS Based on Molecular Dynamics Simulations

    Institute of Scientific and Technical Information of China (English)

    YANG Ping; LIAO Linbo; DING Jianning; YANG Jichang; LI Changsheng; FAN Zen; LIN Zhiyong

    2006-01-01

    The aim of this article was to provide a systematic method to perform molecular dynamics simulation or evaluation for nano-scale interfacial friction behavior between two kinds of materials in MEMS design. Friction is an important factor affecting the performance and reliability of MEMS. The model of the nano-scale interfacial friction behavior between two kinds of materials was presented based on the Newton's equations of motion. The Morse potential function was selected for the model. The improved Verlet algorithm was employed to resolve the model, the atom trajectories and the law of the interfacial friction behavior. Comparisons with experimental data in other paper confirm the validity of the model. Using the model it is possible to simulate or evaluate the importance of different factors for designing of the nano-scale interfacial friction behavior between two kinds of materials in MEMS.

  11. The electrical conductivity characteristics of Fe/Cu nano-scale multilayer materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A mathematical model for describing the relationship betweenelectrical conductivity and the thickness of bilayer, ratio of sublayer thickness of a nano-scale multilayer material (MLM) is presented. Fe/Cu MLM was synthesized by electron beam physical vapor deposition (EB-PVD) technique, and the dependence of electrical conductivity of Fe/Cu MLM on the bilayer thickness and ratio of sublayer thickness were investigated. It is shown that the electrical conductivity of Fe/Cu MLM with fixed ratio of sublayer thickness decreases sharply when the thickness of bilayer becomes thinner than 30 nm. When the bilayer thickness is kept constant, the electrical conductivity linearly decreases with the increasing ratio of sublayer thickness. The values of parameters in the model were obtained by fitting the measured results of electrical conductivity of Fe/Cu MLM with fixed ratio of sublayer thickness. It is found that the calculated values agree well with measured ones.

  12. Assembly and structural analysis of a covalently closed nano-scale DNA cage

    DEFF Research Database (Denmark)

    Andersen, Felicie F; Knudsen, Bjarne; Oliveira, Cristiano Luis Pinto De

    2008-01-01

     The inherent properties of DNA as a stable polymer with unique affinity for partner molecules determined by the specific Watson-Crick base pairing makes it an ideal component in self-assembling structures. This has been exploited for decades in the design of a variety of artificial substrates...... be described as a nano-scale DNA cage, Hence, in theory it could hold proteins or other bio-molecules to enable their investigation in certain harmful environments or even allow their organization into higher order structures...

  13. Nano-scale structure in membranes in relation to enzyme action - computer simulation vs. experiment

    DEFF Research Database (Denmark)

    Høyrup, P.; Jørgensen, Kent; Mouritsen, O.G.

    2002-01-01

    There is increasing theoretical and experimental evidence indicating that small-scale domain structure and dynamical heterogeneity develop in lipid membranes as a consequence of the the underlying phase transitions and the associated density and composition fluctuations. The relevant coherence le...... mixtures show that the enzyme activity is modulated by nano-scale lipid-domain formation in the lipid bilayer and lead to a characteristic lag-burst behavior. The simulations are found to be in semi-quantitative agreement with experimental data....

  14. Nano-scale structure in membranes in relation to enzyme action - computer simulation vs. experiment

    DEFF Research Database (Denmark)

    Høyrup, P.; Jørgensen, Kent; Mouritsen, O.G.

    2002-01-01

    lengths are in the nano-meter range. The nano-scale structure is believed to be important for controlling the activity of enzymes, specifically phospholipases, which act at bilayer membranes. We propose here a lattice-gas statistical mechanical model with appropriate dynamics to account for the non......There is increasing theoretical and experimental evidence indicating that small-scale domain structure and dynamical heterogeneity develop in lipid membranes as a consequence of the the underlying phase transitions and the associated density and composition fluctuations. The relevant coherence......-equilibrium action of the enzyme phospholipase A(2) which hydrolyses lipid-bilayer substrates. The resulting product molecules are assumed to induce local variations in the membrane interfacial pressure. Monte Carlo simulations of the non-equilibrium properties of the model for one-component as well as binary lipid...

  15. Process nano scale mechanical properties measurement of thin metal films using a novel paddle cantilever test structure

    CERN Document Server

    Tong, Chi-Jia

    2008-01-01

    A new technique was developed for studying the mechanical behavior of nano-scale thin metal films on substrate is presented. The test structure was designed on a novel "paddle" cantilever beam specimens with dimensions as few hundred nanometers to less than 10 nanometers. This beam is in triangle shape in order to provide uniform plane strain distribution. Standard clean room processing was used to prepare the paddle sample. The experiment can be operated by using the electrostatic deflection on the paddle uniform distributed stress cantilever beam and then measure the deposited thin metal film materials on top of it. A capacitance technique was used to measurement on the other side of the deflected plate to measure its deflection with respect to the force. The measured strain was converted through the capacitance measurement for the deflection of the cantilever. System performance on the residual stress measurement of thin films are calculated with three different forces on the "paddle" cantilever beam, incl...

  16. 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.

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

    Science.gov (United States)

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

    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 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.

  18. 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.

  19. Water soluble nano-scale transient material germanium oxide for zero toxic waste based environmentally benign nano-manufacturing

    Science.gov (United States)

    Almuslem, A. S.; Hanna, A. N.; Yapici, T.; Wehbe, N.; Diallo, E. M.; Kutbee, A. T.; Bahabry, R. R.; Hussain, M. M.

    2017-02-01

    In the recent past, with the advent of transient electronics for mostly implantable and secured electronic applications, the whole field effect transistor structure has been dissolved in a variety of chemicals. Here, we show simple water soluble nano-scale (sub-10 nm) germanium oxide (GeO2) as the dissolvable component to remove the functional structures of metal oxide semiconductor devices and then reuse the expensive germanium substrate again for functional device fabrication. This way, in addition to transiency, we also show an environmentally friendly manufacturing process for a complementary metal oxide semiconductor (CMOS) technology. Every year, trillions of complementary metal oxide semiconductor (CMOS) electronics are manufactured and billions are disposed, which extend the harmful impact to our environment. Therefore, this is a key study to show a pragmatic approach for water soluble high performance electronics for environmentally friendly manufacturing and bioresorbable electronic applications.

  20. Water soluble nano-scale transient material germanium oxide for zero toxic waste based environmentally benign nano-manufacturing

    KAUST Repository

    Almuslem, A. S.

    2017-02-14

    In the recent past, with the advent of transient electronics for mostly implantable and secured electronic applications, the whole field effect transistor structure has been dissolved in a variety of chemicals. Here, we show simple water soluble nano-scale (sub-10 nm) germanium oxide (GeO) as the dissolvable component to remove the functional structures of metal oxide semiconductor devices and then reuse the expensive germanium substrate again for functional device fabrication. This way, in addition to transiency, we also show an environmentally friendly manufacturing process for a complementary metal oxide semiconductor (CMOS) technology. Every year, trillions of complementary metal oxide semiconductor (CMOS) electronics are manufactured and billions are disposed, which extend the harmful impact to our environment. Therefore, this is a key study to show a pragmatic approach for water soluble high performance electronics for environmentally friendly manufacturing and bioresorbable electronic applications.

  1. Large scale molecular simulations with application to polymers and nano-scale materials

    Science.gov (United States)

    Gao, Guanghua

    There remain practical problems to predicting structures and properties of materials from first principles, though the foundation, quantum mechanics, has been established for many years. The goals of this research are to develop methods and tools that are accurate and practical, and apply them to important problems. Two aspects of the methodology are focused. (1) The development of accurate force fields based on ab initio quantum mechanical calculations on prototype systems. Procedures were developed on polyvinyl chloride (PVC) and successfully applied on other types of polymers. They are very important to studying of amorphous polymers materials, for which current methods have not been useful in predicting important properties (e.g. moduli and glass temperature). (2) The development of Massive Parallel Simulation (MPSim) Software. MPSim is suitable for large systems (millions of atoms). It has the ability of including environmental variables (temperature, pressure, tension, and shear) and extracting physical properties (moduli and glass temperatures). The theories and algorithms implemented are summarized in the Appendix. These methods and tools are applied to the accurate simulation of structures and properties of amorphous polymer materials and nano-materials. Molecular dynamics (MD) simulation on polyethylene (chapter 6) was used to develop a general strategy for predicting glass transition temperatures which is expected to be very important in polymer industry. In chapter 7, these strategies were successfully applied to three important fluoro polymers. Single-walled carbon nanotubes (SWNT), recently discovered but not very well characterized, is an interesting new class of materials. Using an accurate force field, structures and mechanical properties of these systems are studied. Chapter 2 shows that the dominating factor for deciding stable structures and mechanical properties is the tube size, not chirality. The behavior of (10, 10) nano-tube under bending

  2. Nano-scale gap filling and mechanism of deposit-etch-deposit process for phase-change material

    Institute of Scientific and Technical Information of China (English)

    Ren Wan-Chun; Liu Bo; Song Zhi-Tang; Xiang Yang-Hui; Wang Zong-Tao; Zhang Bei-Chao; Feng Song-Lin

    2012-01-01

    Ge2Sb2Te5 gap filling is one of the key processes for phase-change random access memory manufacture.Physical vapor deposition is the mainstream method of Ge2Sb2Te5 film deposition due to its advantages of film quality,purity,and accurate composition control.However,the conventional physical vapor deposition process cannot meet the gapfilling requirement with the critical device dimension scaling down to 90 nm or below.In this study,we find that the deposit-etch-deposit process shows better gap-filling capability and scalability than the single-step deposition process,especially at the nano-scale critical dimension.The gap-filling mechanism of the deposit-etch-deposit process was briefly discussed.We also find that re-deposition of phase-change material from via the sidewall to via the bottom by argon ion bombardment during the etch step was a key ingredient for the final good gap filling.We achieve void-free gap filling of phase-change material on the 45-nm via the two-cycle deposit-etch-deposit process.We gain a rather comprehensive insight into the mechanism of deposit-etch-deposit process and propose a potential gap-filling solution for over 45-nm technology nodes for phase-change random access memory.

  3. Construction of Binary Cooperative Nano-scale Interfacial Materials with Special Wettability (Superhydrophobicity/Superhydrophilicity)

    Institute of Scientific and Technical Information of China (English)

    JIANG Lei; ZHAI Jin; SONG Yanlin; LI Yuliang; ZHU Daoben

    2007-01-01

    @@ This project was started by learning the biological surface structures with special wettabilities in nature at first, and selects some typical ones to reveal the mechanism about the special wettabilities on their surface. Via scrutinizing the micro-structure on the surface of a lotus leaf, the project's scientists discover that the coordinated role exerted by the leaf surface's micro-/nano- composite structure and the wax-like secretion is the key point that gives rise to the self-clearance of the leaf.

  4. Micro/nano Scale Mechanics and Intelligent Material-The First Creative Research Group in Mechanics

    Institute of Scientific and Technical Information of China (English)

    Kezhi Huang; Wei Yang; Quangshui Zheng; Daining Fang

    2006-01-01

    @@ As the first Creative Research Group sponsored by Division of Mechanics of Department of Mathematical and Physical Sciences of NSFC,a project team,including two CAS members (Porf.Kezhi Huang,Prof.Wei Yang) and two Changjiang scholars (Prof.Quanshui Zheng,Prof.Daining Fang) from Tsinghua University,focused their research on "Micro/nanoscale mechanics and smart materials",and progressed in the following:

  5. 3-Dimensional Nano-Scale Reinforcement Architecture for Advanced Composite Structures

    Science.gov (United States)

    2008-10-01

    principal mechanism which makes polybenzoxazoles , polyimides, polybenzimidazoles, as well as aramids (to a lesser extent) heat resistant fibers . In order to...Geometrical, Structural and Mechanical Characterizations of the Dry CNT Yarns and 3-D raids 77 6.1. Baseline Tensile Testing of Carbon Fiber ...Fabricate on 3TEX\\s micro-braiding apparatus continuous samples of 3-D braided preform made of carbon nanotube yarns and their hybrid with glass fibers

  6. Structure Analysis and Optical Parameters of Nano-scale ZnSe/Flexible Substrate Thin Film

    Science.gov (United States)

    Shaaban, E. R.; Yahia, I. S.; Sharaf, E. R.

    2016-09-01

    The ZnSe thin films with different thicknesses have been deposited on polymer substrates for flexible optical devices applications. The XRD of different thicknesses for ZnSe films reveals the cubic structure of the films oriented along the (1 1 1) direction. The structural parameters such as particle size (40.41-105.24 nm) and lattice strain (6.5 × 10-3-14.7 × 10-3 lin-2m-4) were evaluated. Also AFM was used in order to obtain quantitative information on microstructure properties. The optical constants, the refractive index n and the absorption index k have been calculated from transmittance T and reflectance R through the spectral range of 400-2500 nm using Swanepoel's method. The optical constants (n, k) were calculated in medium and transparent regions. The energy gap of direct transition for polycrystalline ZnSe thin films was calculated in the strong absorption region and found to be increased from 2.55 eV to 2.70 eV with the increasing the film thickness. ZnSe/flexible substrates are good candidates for optoelectronic devices.

  7. Nano-scale structure and mechanical properties of the human dentine-enamel junction.

    Science.gov (United States)

    Chan, Y L; Ngan, A H W; King, N M

    2011-07-01

    Despite being an interface between two mechanically mismatched phases of the soft dentine and hard enamel, the dentine-enamel junction (DEJ) in a human tooth is in general capable of withstanding a long working life of repeated dynamic loading. The current poor understanding of the structure and properties of the DEJ has presented a major obstacle to designing better therapeutic protocols for complications concerning the DEJ. In this investigation, it was discovered that the DEJ is a thin, but gradual interface with characteristics transiting from those of dentine to those of enamel. The collagen fibres in dentine enter into the enamel side of the DEJ and terminate in a region in which the hydroxyapatite crystals begin to show enamel characteristics. Using focused ion beam machining, micro-beams were fabricated from regions within 50 μm of the DEJ and were subjected to bend tests. In spite of the similarity in the flexural strength of the DEJ and enamel, fractographs revealed cracks in the DEJ that propagated along structures with dentine characteristics. To the best of our knowledge, this is the first report on the testing of the mechanical properties of the DEJ.

  8. Pulse-biased etching of Si3N4-layer in capacitively-coupled plasmas for nano-scale patterning of multi-level resist structures.

    Science.gov (United States)

    Lee, Hyelim; Kim, Sechan; Choi, Gyuhyun; Lee, Nae-Eung

    2014-12-01

    Pulse-biased plasma etching of various dielectric layers is investigated for patterning nano-scale, multi-level resist (MLR) structures composed of multiple layers via dual-frequency, capacitively-coupled plasmas (CCPs). We compare the effects of pulse and continuous-wave (CW) biasing on the etch characteristics of a Si3N4 layer in CF4/CH2F2/O2/Aretch chemistries using a dual-frequency, superimposed CCP system. Pulse-biasing conditions using a low-frequency power source of 2 MHz were varied by controlling duty ratio, period time, power, and the gas flow ratio in the plasmas generated by the 27.12 MHz high-frequency power source. Application of pulse-biased plasma etching significantly affected the surface chemistry of the etched Si3N4 surfaces, and thus modified the etching characteristics of the Si3N4 layer. Pulse-biased etching was successfully applied to patterning of the nano-scale line and space pattern of Si3N4 in the MLR structure of KrF photoresist/bottom anti-reflected coating/SiO2/amorphous carbon layer/Si3N4. Pulse-biased etching is useful for tuning the patterning of nano-scale dielectric hard-mask layers in MLR structures.

  9. 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.

  10. Characterizing the nano-structure and defect structure of nano-scaled non-ferrous structural alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ghamarian, Iman, E-mail: imanghamarian@yahoo.com [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Samimi, Peyman; Liu, Yue [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Center for Advanced Non-Ferrous Structural Alloys, an NSF-I/UCRC between the University of North Texas (Denton, TX, 76203) and the Colorado School of Mines (Golden, CO, 80401) (United States); Poorganji, Behrang; Vasudevan, Vijay K. [Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221 (United States); Collins, Peter C. [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Center for Advanced Non-Ferrous Structural Alloys, an NSF-I/UCRC between the University of North Texas (Denton, TX, 76203) and the Colorado School of Mines (Golden, CO, 80401) (United States)

    2016-03-15

    The presence and interaction of nanotwins, geometrically necessary dislocations, and grain boundaries play a key role in the mechanical properties of nanostructured crystalline materials. Therefore, it is vital to determine the orientation, width and distance of nanotwins, the angle and axis of grain boundary misorientations as well as the type and the distributions of dislocations in an automatic and statistically meaningful fashion in a relatively large area. In this paper, such details are provided using a transmission electron microscope-based orientation microscopy technique called ASTAR™/precession electron diffraction. The remarkable spatial resolution of this technique (~ 2 nm) enables highly detailed characterization of nanotwins, grain boundaries and the configuration of dislocations. This orientation microscopy technique provides the raw data required for the determination of these parameters. The procedures to post-process the ASTAR™/PED datasets in order to obtain the important (and currently largely hidden) details of nanotwins as well as quantifications of dislocation density distributions are described in this study. - Highlights: • EBSD cannot characterize defects such as dislocations, grain boundaries and nanotwins in severely deformed metals. • TEM based orientation microscopy technique called ASTAR™/PED was used to resolve the problem. • Locations and orientations of nanotwins, dislocation density distribution and grain boundary characters can be resolved. • This work provides the bases for further studies on the interactions between dislocations, grain boundaries and nanotwins. • The computation part is explained sufficiently which helps the readers to post process their own data.

  11. Investigation of the Structural, Electrical, and Optical Properties of the Nano-Scale GZO Thin Films on Glass and Flexible Polyimide Substrates

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2016-05-01

    Full Text Available In this study, Ga2O3-doped ZnO (GZO thin films were deposited on glass and flexible polyimide (PI substrates at room temperature (300 K, 373 K, and 473 K by the radio frequency (RF magnetron sputtering method. After finding the deposition rate, all the GZO thin films with a nano-scale thickness of about 150 ± 10 nm were controlled by the deposition time. X-ray diffraction patterns indicated that the GZO thin films were not amorphous and all exhibited the (002 peak, and field emission scanning electron microscopy showed that only nano-scale particles were observed. The dependences of the structural, electrical, and optical properties of the GZO thin films on different deposition temperatures and substrates were investigated. X-ray photoemission spectroscopy (XPS was used to measure the elemental composition at the chemical and electronic states of the GZO thin films deposited on different substrates, which could be used to clarify the mechanism of difference in electrical properties of the GZO thin films. In this study, the XPS binding energy spectra of Ga2p3/2 and Ga2p1/2 peaks, Zn2p3/2 and Zn2p1/2 peaks, the Ga3d peak, and O1s peaks for GZO thin films on glass and PI substrates were well compared.

  12. Characterization of multi-scale porous structure of fly ash/phosphate geopolymer hollow sphere structures: from submillimeter to nano-scale.

    Science.gov (United States)

    Li, Ruifeng; Wu, Gaohui; Jiang, Longtao; Sun, Dongli

    2015-01-01

    In the present work, the porous structure of fly ash/phosphate geopolymer hollow sphere structures (FPGHSS), prepared by pre-bonding and curing technology, has been characterized by multi-resolution methods from sub-millimeter to nano-scale. Micro-CT and confocal microscopy could provide the macroscopic distribution of porous structure on sub-millimeter scale, and hollow fly ashes with sphere shape and several sub-millimeter open cells with irregular shape were identified. SEM is more suitable to illustrate the distribution of micro-sized open and closed cells, and it was found that the open cells of FPGHSS were mainly formed in the interstitial porosity between fly ashes. Mercury porosimeter measurement showed that the micro-sized open cell of FPGHSS demonstrated a normal/bimodal distribution, and the peaks of pore size distribution were mainly around 100 and 10 μm. TEM observation revealed that the phosphate geopolymer was mainly composed of the porous area with nano-pores and dense areas, which were amorphous Al-O-P phase and α-Al2O3 respectively. The pore size of nano-pores demonstrated a quasi-normal distribution from about 10 to 100 nm. Therefore, detailed information of the porous structure of FPGHSS could be revealed using multiple methods.

  13. Nano-Scale Au Supported on Carbon Materials for the Low Temperature Water Gas Shift (WGS Reaction

    Directory of Open Access Journals (Sweden)

    Paula Sánchez

    2011-12-01

    Full Text Available Au-based catalysts supported on carbon materials with different structures such as graphite (G and fishbone type carbon nanofibers (CNF-F were prepared using two different methods (impregnation and gold-sol to be tested in the water gas shift (WGS reaction. Atomic absorption spectrometry, transmission electron microscopy (TEM, temperature-programmed oxidation (TPO, X-ray diffraction (XRD, Raman spectroscopy, elemental analyses (CNH, N2 adsorption-desorption analysis, temperature-programmed reduction (TPR and temperature-programmed decomposition were employed to characterize both the supports and catalysts. Both the crystalline nature of the carbon supports and the method of gold incorporation had a strong influence on the way in which Au particles were deposited on the carbon surface. The higher crystallinity and the smaller and well dispersed Au particle size were, the higher activity of the catalysts in the WGS reaction was noted. Finally, catalytic activity showed an important dependence on the reaction temperature and steam-to-CO molar ratio.

  14. MOLECULAR DYNAMICS SIMULATION OF SELF-ORGANIZED STRUCTURE IN MICRO-PHASE SEPARATION OF NANO-SCALE FILM

    Institute of Scientific and Technical Information of China (English)

    Dexiang Tang; Wei Ge; Jinghai Li

    2004-01-01

    Self-organization in thin micro-films has shown potential for the production of microelements with specific structures and functions; however, little is known about its mechanism of formation. A 2-D molecular dynamics (MD)simulation on this process is carried out in this paper for films between two parallel walls (substrates) under different initial conditions. The films consist of two immiscible components (A and B). The simulation results in alternative columns perpendicular to the walls, which are rich either in A or in B molecules, respectively, apparently owing to their different interactions with the walls. The characteristic breadths of the columns depend on the distance between the two walls. By providing microscopic details of the self-organization processes and the resulted structures, MD simulation proves itself as a unique way for analyzing the dynamics of thin films.

  15. Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy for mapping nano-scale distribution of organic carbon forms in soil: Application to black carbon particles

    Science.gov (United States)

    Lehmann, Johannes; Liang, Biqing; Solomon, Dawit; Lerotic, Mirna; LuizãO, Flavio; Kinyangi, James; SchäFer, Thorsten; Wirick, Sue; Jacobsen, Chris

    2005-03-01

    Small-scale heterogeneity of organic carbon (C) forms in soils is poorly quantified since appropriate analytical techniques were not available up to now. Specifically, tools for the identification of functional groups on the surface of micrometer-sized black C particles were not available up to now. Scanning Transmission X-ray Microscopy (STXM) using synchrotron radiation was used in conjunction with Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy to investigate nano-scale distribution (50-nm resolution) of C forms in black C particles and compared to synchrotron-based FTIR spectroscopy. A new embedding technique was developed that did not build on a C-based embedding medium and did not pose the risk of heat damage to the sample. Elemental sulfur (S) was melted to 220°C until it polymerized and quenched with liquid N2 to obtain a very viscous plastic S in which the black C could be embedded until it hardened to a noncrystalline state and was ultrasectioned. Principal component and cluster analysis followed by singular value decomposition was able to resolve distinct areas in a black carbon particle. The core of the studied biomass-derived black C particles was highly aromatic even after thousands of years of exposure in soil and resembled the spectral characteristics of fresh charcoal. Surrounding this core and on the surface of the black C particle, however, much larger proportions of carboxylic and phenolic C forms were identified that were spatially and structurally distinct from the core of the particle. Cluster analysis provided evidence for both oxidation of the black C particle itself as well as adsorption of non-black C. NEXAFS spectroscopy has great potential to allow new insight into black C properties with important implications for biogeochemical cycles such as mineralization of black C in soils and sediments, and adsorption of C, nutrients, and pollutants as well as transport in the geosphere, hydrosphere, and atmosphere.

  16. Micro-and/or nano-scale patterned porous membranes, methods of making membranes, and methods of using membranes

    KAUST Repository

    Wang, Xianbin

    2015-01-22

    Embodiments of the present disclosure provide for materials that include a pre-designed patterned, porous membrane (e.g., micro- and/or nano-scale patterned), structures or devices that include a pre-designed patterned, porous membrane, methods of making pre-designed patterned, porous membranes, methods of separation, and the like.

  17. Failure and deformation mechanisms at macro- and nano-scales of alkali activated clay

    Science.gov (United States)

    Sekhar Das, Pradip; Bhattacharya, Manjima; Chanda, Dipak Kr; Dalui, Srikanta; Acharya, Saikat; Ghosh, Swapankumar; Mukhopadhyay, Anoop Kumar

    2016-06-01

    Here we report two qualitative models on failure and deformation mechanisms at macro- and nano-scales of alkali activated clay (AACL), a material of extraordinary importance as a low cost building material. The models were based on experimental data of compressive failure and nanoindentation response of the AACL materials. A 420% improvement in compressive strength (σ c) of the AACL was achieved after 28 days (d) of curing at room temperature and it correlated well with the decrements in the residual alkali and pH concentrations with the increase in curing time. Based on extensive post-mortem FE-SEM examinations, a schematic model for the compressive failure mechanism of AACL was proposed. In addition, the nanoindentation results of AACL provided the first ever experimental evidence of the presence of nano-scale plasticity and a nano-scale contact deformation resistance that increased with the applied load. These results meant the development of a unique strain tolerant microstructure in the AACL of Indian origin. The implications of these new observations were discussed in terms of a qualitative model based on the deformation of layered clay structure.

  18. CATALYST TECHNOLOGY DEVELOPMENT FROM MACRO-,MICRO- DOWN TO NANO-SCALE

    Institute of Scientific and Technical Information of China (English)

    Wei Liu

    2005-01-01

    Catalyst and catalytic process technology has been an ever-growing field that involves chemical engineering, chemistry, and material science. A number of excellent review articles and books have been published on the subject. In this work, the author reviews the evolution and development of catalyst products with multi-scale methodology.The catalyst technologies are classified into three levels, macro-scale (reactor size), mini- and micro-scale (catalyst unit),and nano-scale (catalyst intrinsic structures). Innovation at different scales requires different sets of expertise, method,and knowledge. Specific examples of significant impact to practical application are used to illustrate technology development at each scale. The multi-scale analysis enables clear delineation of technology components and their relationship for a catalyst product and catalytic process. Manipulation of catalyst structures at nano-scale to increase intrinsic activity and/or selectivity is considered of large potential for future catalyst product development. Recent research results on Cu-CeO2 and Au-CeO2 composite catalysts for air pollution control and hydrogen production are used to show how novel catalytic properties can be discovered by unique combination of different but common materials at the nano-scale.

  19. Thermoelectric effect in nano-scaled lanthanides doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Otal, E H; Canepa, H R; Walsoee de Reca, N E [Centro de Investigacion en Solidos, CITEFA, San Juan Bautista de La Salle 4397 (B1603ALO) Villa Martelli, Buenos Aires (Argentina); Schaeuble, N; Aguirre, M H, E-mail: canepa@citefa.gov.a, E-mail: myriam.aguirre@empa.c [Solid State Chemistry and Catalysis, Empa, Swiss Federal Laboratories for Materials Testing and Research, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)

    2009-05-01

    Start Nano-scaled ZnO with 1% Er doping was prepared by soft chemistry methods. The synthesis was carried out in anhydrous polar solvent to achieve a crystal size of a few nanometers. Resulting particles were processed as precipitates or multi layer films. Structural characterization was evaluated by X-Ray diffraction and transmission and scanning electron microscopy. In the case of films, UV-Vis characterization was made. The thermoelectrical properties of ZnO:Er were evaluated and compared with a typical good thermoelectric material ZnO:Al. Both materials have also shown high Seebeck coefficients and they can be considered as potential compounds for thermoelectric conversion.

  20. Programmable Technologies for Micro- and Nano-Scale Pattern and Material Transfer and Possible Applications for Control of Self-Assembly

    Science.gov (United States)

    2003-04-01

    is sometimes a consideration. INFORMATION MATERIAL INFORMATION INFORMATION MATERIAL ENERGY INFORMATION E ATERGY ENERGY MATERIA ,," MATERIAL ENsERGY...50 cm/sec MANY FLOW-GUIDED 25 Few 0lSmm 3 Ise4 MANY THERMAL SPRAY >500 -50 5-50 cm/sec MANY PLASMA SPRAY >500 >5 1_ _ MANY Figure 9. Characteristics

  1. Modeling nano-scale grain growth of intermetallics

    Indian Academy of Sciences (India)

    Mohsen Kazeminezhad

    2009-02-01

    The Monte Carlo simulation is utilized to model the nano-scale grain growth of two nanocrystalline materials, Pd81Zr19 and RuAl. In this regard, the relationship between the real time and the time unit of simulation, i.e. Monte Carlo step (MCS), is determined. The results of modeling show that with increasing time of heating, the grain sizes of both nano-crystalline materials increased as in the case of conventional materials. Moreover, it is found that for both nano-crystalline materials the relationship between the real time and MCS is in power law form, which is linear for the conventional materials.

  2. Method of producing exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    Science.gov (United States)

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z.

    2010-11-02

    The present invention provides a method of exfoliating a layered material (e.g., graphite and graphite oxide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm. The method comprises (a) dispersing particles of graphite, graphite oxide, or a non-graphite laminar compound in a liquid medium containing therein a surfactant or dispersing agent to obtain a stable suspension or slurry; and (b) exposing the suspension or slurry to ultrasonic waves at an energy level for a sufficient length of time to produce separated nano-scaled platelets. The nano-scaled platelets are candidate reinforcement fillers for polymer nanocomposites. Nano-scaled graphene platelets are much lower-cost alternatives to carbon nano-tubes or carbon nano-fibers.

  3. Nano-scale Electrodes for Molecular/Organic Electronics

    Institute of Scientific and Technical Information of China (English)

    K.Tsukagoshi

    2007-01-01

    1 Results Nanometer-scale electrodes with a nano-junction allow us to investigate conduction properties of nano-materials. Because many nano-materials usually form grain boundaries or domain boundaries with high tunneling resistance, it is difficult to investigate the intrinsic properties through a series of tunneling resistance. To make direct contact with the single nano-material, such as a single polymer string, we developed nano-scale electrodes. By using these nano-electrodes as new tool, we invest...

  4. Mechanics over micro and nano scales

    CERN Document Server

    Chakraborty, Suman

    2011-01-01

    Discusses the fundaments of mechanics over micro and nano scales in a level accessible to multi-disciplinary researchers, with a balance of mathematical details and physical principles Covers life sciences and chemistry for use in emerging applications related to mechanics over small scales Demonstrates the explicit interconnection between various scale issues and the mechanics of miniaturized systems

  5. Current Progress of Mechanical Properties of Metals with Nano-scale Twins

    Institute of Scientific and Technical Information of China (English)

    Lei LU

    2008-01-01

    Focus on face-centered cubic (fcc) metals with nano-scale twins lamellar structure, this paper presents a brief overview of the recent progress made in improving mechanical properties, including strength, ductility, work hardening, strain rate sensitivities, and in mechanistically understanding the underling deformation mechanisms. Significant developments have been achieved in nano-twinned fcc metals with a combination of high strength and considerable ductility at the same time, enhanced work hardening ability and enhanced rate sensitivity. The findings elucidate the role of interactions between dislocations and twin boundaries (TBs) and their contribution to the origin of outstanding properties. The computer simulation analysis accounts for high plastic anisotropy and rate sensitivity anisotropy by treating TBs as internal interfaces and allowing special slip geometry arrangements that involve soft and hard modes of deformation. Parallel to the novel mechanical behaviors of the nano-twinned materials, the investigation and developments of nanocrystalline materials are also discussed in this overview for comparing the contribution of grain boundaries/TBs and grain size/twin lamellar spacing to the properties. The recent advances in the experimental and computational studies of plastic deformation of the fcc metals with nano-scale twin lamellar structures provide insights into the possible means of optimizing comprehensive mechanical properties through interfacial engineering.

  6. Probing the structure and nano-scale mechanical properties of polymer surfaces with scanning force microscopy and sum frequency vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gracias, David Hugo [Univ. of California, Berkeley, CA (United States)

    1999-05-01

    Scanning Force Microscopy (SFM) has been used to quantitatively measure the elastic modulus, friction and hardness of polymer surfaces with special emphasis on polyethylene and polypropylene. In the experiments, tips of different radii of curvature ranging from 20 nm to 1000 nm have been used and the high pressure applied by the SFM have been observed to affect the values obtained in the measurements. The contact of the SFM tip with the polymer surface is explained by fitting the experimental curves to theoretical predictions of contact mechanics. Sum Frequency Generation (SFG) Vibrational Spectroscopy has been used to measure vibrational spectra of polymer surfaces in the vibrational range of 2700 to 3100 cm-1. Strong correlations are established between surface chemistry and surface structure as probed by SFG and mechanical properties measured by SFM on the surfaces. In these studies segregation of low surface energy moieties, from the bulk of the polymer to the surface have been studied. It was found that surface segregation occurs in miscible polymer blends and a small concentration of surface active polymer can be used to totally modify the surface properties of the blend. A novel high vacuum SFM was built to do temperature dependent measurements of mechanical changes occurring at the surface of polypropylene during the glass transition of the polymer. Using this instrument the modulus and friction of polypropylene was measured in the range of room temperature to ˜-60°C. An increase in the ordering of the backbone of the polymer chains below the glass transition measured by SFG correlates well with the increase in modulus measured on the same surface with SFM. Friction measurements have been done on polyethylene with three different instruments by applying loads ranging from nN to sub newton i.e. over eight orders of magnitude. Pressure and contact area effects were observed to play a significant role in determining the frictional response of the polymer

  7. Mechanisms of heat transport across a nano-scale gap in heat assisted magnetic recording

    Science.gov (United States)

    Budaev, Bair V.; Bogy, David B.

    2012-06-01

    This paper compares different mechanisms of heat transport across nano-scale gaps and discusses the role of electromagnetic phenomena in heat transport in general nano-scale layered structures. The results of the analysis suggest that heat transfer across sub-5 nm gaps like that appearing in prototypes of heat assisted magnetic recording (HAMR) systems is dominated by direct intermolecular interactions between the separated bodies and is little affected by electromagnetic radiation. The analysis further suggests that local heating for HAMR with sub-5 nm spacing can be more efficiently achieved by a Joule heater that is simpler to fabricate than laser-based optical systems and is less destructive for the nano-scale transducers than laser radiation, which may lead to their structural damage and short duration life of nanoscale transducers.

  8. Investigation of the Static and Dynamic Mechanical Properties of Nano-scale Water

    Science.gov (United States)

    Stambaugh, Corey; Kwon, Soyoung; Jhe, Wonho

    2011-03-01

    The behavior of liquids on the nano-scale has become an area of interest as new fabrication techniques have allowed for increasingly smaller structures to be made. While much work has been done on the interactions forces at liquid and solid interfaces, questions still remain regarding the behavior of nano-scale liquids. By incorporating a micro-electromechanical force sensor (MEMS) into the quartz tuning fork based atomic force microscope (QTF-AFM) probe setup we are able to both manipulate and measure nano-scale water, which in turn provides information beyond the standard AFM approach. Here we look at both the static and dynamic mechanical properties of water formed between the tip of a (QTF-AFM) probe and the polysilicon surface of a MEMS device. Work supported by NSF grant OISE #0853104.

  9. Issues of structure formation of multi-component construction materials

    Directory of Open Access Journals (Sweden)

    Sidorenko Yulia

    2017-01-01

    Full Text Available Growing volumes of construction result in the rising demand for high-quality wall materials and products, growing relevance of availability of resource and raw-material base of natural and industrial products for the construction industry. Structural, physical and mechanical qualities of these products can be improved through systematical selection of compositions based on natural and raw materials, including nano-scale products. The goal of this paper is to provide rationale for structure formation mechanisms of multicomponent materials (silica-lime, silicate, cement materials, with the possibility of using nano-scale products in their production. The primary mechanism of directed structure formation at the interface boundaries of binders are nano- and ultra-disperse particles with high absorption and adhesion properties, which are primarily intended to strengthen the contact area (one of the key structural units of multicomponent binders. The knowledge of genesis, chemical, mineralogical, and phase compositions, as well as specific features of formation of nano-technological raw materials, enables optimization of construction product properties. Using the small-angle neutron scattering method, we identified granulometric and surface properties of a series of nano-technological products (binary and sludge and materials where such products are used, which enabled us to design optimal mixture compositions and parameters of pressing operations.

  10. 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.

  11. EFFICIENT NANO-SCALE ADMIXTURE FOR FOAM STABILITY IMPROVEMENT OF CELLULAR CONCRETES

    Directory of Open Access Journals (Sweden)

    Grishina Аnna Nikolaevna

    2012-10-01

    Full Text Available The authors present their methodology of synthesis of a nano-scale additive designated for the stabilization of synthetic foaming agents. The nano-scale admixture is composed of iron hydroxide (III sol and aqueous sodium hydro silicates (water glass. Besides the above method, the topological structural model of the nano-scale additive is proposed. The additive stability was assessed upon its one-day storage (with the foaming agent added, and the assessment data are provided in the article. The authors have discovered that it is advisable to use an iron chloride solution in the concentration of 1 % to manufacture the iron hydroxide (III sol. The authors have also discovered that the rate of jellification goes up in the process of injecting the foaming agent into the foam that contains the nano-scale admixture developed by the authors. Dependence between the amount of sodium hydro silicate and the viscosity of the system composed of the water glass and the sol of iron hydroxide (III is examined in detail. The authors have identified that the average water glass viscosity curve demonstrates an extreme nature. The additive is used for the stabilization of the foam generated by synthetic foaming agents. The injection of the proposed additive improves foam stability. It is noteworthy that this positive result is free from any negative side effects.

  12. Contact engineering for nano-scale CMOS

    KAUST Repository

    Hussain, Muhammad Mustafa

    2012-09-10

    High performance computation with longer battery lifetime is an essential component in our today\\'s digital electronics oriented life. To achieve these goals, field effect transistors based complementary metal oxide semiconductor play the key role. One of the critical requirements of transistor structure and fabrication is efficient contact engineering. To catch up with high performance information processing, transistors are going through continuous scaling process. However, it also imposes new challenges to integrate good contact materials in a small area. This can be counterproductive as smaller area results in higher contact resistance thus reduced performance for the transistor itself. At the same time, discovery of new one or two-dimensional materials like nanowire, nanotube, or atomic crystal structure materials, introduces new set of challenges and opportunities. In this paper, we are reviewing them in a synchronized fashion: fundamentals of contact engineering, evolution into non-planar field effect transistors, opportunities and challenges with one and two-dimensional materials and a new opportunity of contact engineering from device architecture perspective. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 锂离子电池纳米锂锰氧化物正极材料的研究进展%Research Progress in Nano-scale Lithium Manganese Oxide as Cathode Material for Lithium Ion Batteries

    Institute of Scientific and Technical Information of China (English)

    曾丽珍

    2012-01-01

    综述了近年来锂离子电池正极材料锂锰氧化物的研究现状,重点对锂锰氧化物的结构和性能的关系,尖晶石锂锰氧化物的制备以及其改性研究进行了阐述。%New progress of nanotechnology applied in lithium ion battery of lithium manganese oxide as cathode material was summarized during recent years,focusing on the relationship between structure and properties of lithium manganese oxide,the preparation methods of nanometer lithium manganese oxide materials cathode material and modification of spinel lithium manganese oxide materials were described.

  14. Fabrication of nano scaled protein monolayer consisting of cytochrome c on self-assembled 11-MUA layer for bioelectronic device.

    Science.gov (United States)

    Lee, Taek; Kim, Sang-Uk; Lee, Jin-Ho; Min, Junhong; Choi, Jeong-Woo

    2009-12-01

    The biomolecular/organic hetero-structure films (cytochrome c/11-mercapto-undecanoic acid) on gold substrates were controlled and fabricated with molecular level for developing valuable molecular electronic devices. Cytochrome c is a metalloprotein having redox property, which can be directly applicable to biomemory device as a active element. For efficient immobilization of the protein on the gold substrate, 11-mercapto-undecanoic acid (11-MUA) was used as a linker material between protein and inorganic substrate. The proposed nano scaled biomolecular/organic hetero-structure layer (cytochrome c/11-MUA) on gold surface was investigated by using surface plasmon resonance technique. The molecular morphology of the fabricated protein layer was confirmed by scanning tunneling microscopy. Electrochemical properties of fabricated biomolecular/organic hetero layer were verified using cyclic voltammetry. Their redox properties was sustained over 1000 cycles of cyclic voltametry. It proved that the fabricated film was a suitable platform for the bioelectronic device application.

  15. Deposition of Nano-Scaled Coatings Using Inductively Coupled Plasma

    Institute of Scientific and Technical Information of China (English)

    D H Jung; B Park; J J Lee

    2004-01-01

    Nano-scaled Ti-B-N coatings could be produced by inductively coupled plasma (ICP) assisted magnetron spurtering. The properties and microstructure of the coating can be changed drastically by applying ICP to conventional magnetron sputtering. In this work, an internal type rf ICP process is used. The core of this technology is the efficient production and control of self-depositing ions and reactive gas ions by an induced electric field. Ti-B-N coatings were prepared by using a TiB2 target and a gas mixture of N2 and Ar at 200 ℃ and a pressure of 60 mTorr. In addition to ICP, the effect of the substrate bias voltage on the structure and properties of the coating was investigated. By applying ICP and a bias voltage to the substrate the hardness of the Ti-B-N coating is increased by more than 75 GPa, as a result of enhanced ionization in the plasma. The Ti-B-N coating, which has the highest hardness, shows the best surface uniformity and a very dense structure with a grain size of 3 nm. This sample also shows a high crystallinity compared to the coating prepared using other deposition parameters.

  16. Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review

    Directory of Open Access Journals (Sweden)

    Enrico Bernardo

    2014-03-01

    Full Text Available Preceramic polymers, i.e., polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings or functional (bioactive ceramics, luminescent materials, mainly relies on modifications of the polymers at the nano-scale, i.e., on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs, or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix.

  17. Nano-scaled graphene platelets with a high length-to-width aspect ratio

    Science.gov (United States)

    Zhamu, Aruna; Guo, Jiusheng; Jang, Bor Z.

    2010-09-07

    This invention provides a nano-scaled graphene platelet (NGP) having a thickness no greater than 100 nm and a length-to-width ratio no less than 3 (preferably greater than 10). The NGP with a high length-to-width ratio can be prepared by using a method comprising (a) intercalating a carbon fiber or graphite fiber with an intercalate to form an intercalated fiber; (b) exfoliating the intercalated fiber to obtain an exfoliated fiber comprising graphene sheets or flakes; and (c) separating the graphene sheets or flakes to obtain nano-scaled graphene platelets. The invention also provides a nanocomposite material comprising an NGP with a high length-to-width ratio. Such a nanocomposite can become electrically conductive with a small weight fraction of NGPs. Conductive composites are particularly useful for shielding of sensitive electronic equipment against electromagnetic interference (EMI) or radio frequency interference (RFI), and for electrostatic charge dissipation.

  18. Volume changes at macro- and nano-scale in epoxy resins studied by PALS and PVT experimental techniques

    Energy Technology Data Exchange (ETDEWEB)

    Somoza, A. [IFIMAT-UNCentro, Pinto 399, B7000GHG Tandil (Argentina) and CICPBA, Pinto 399, B7000GHG Tandil (Argentina)]. E-mail: asomoza@exa.unicen.edu.ar; Salgueiro, W. [IFIMAT-UNCentro, Pinto 399, B7000GHG Tandil (Argentina); Goyanes, S. [LPMPyMC, Depto. de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); Ramos, J. [Materials and Technology Group, Departamento de Ingenieria Quimica y M. Ambiente, Escuela University Politecnica, Universidad Pais Vasco/Euskal Herriko Unibertsitatea, Pz. Europa 1, 20018 Donostia/San Sebastian (Spain); Mondragon, I. [Materials and Technology Group, Departamento de Ingenieria Quimica y M. Ambiente, Escuela University Politecnica, Universidad Pais Vasco/Euskal Herriko Unibertsitatea, Pz. Europa 1, 20018 Donostia/San Sebastian (Spain)

    2007-02-15

    A systematic study on changes in the volumes at macro- and nano-scale in epoxy systems cured with selected aminic hardeners at different pre-cure temperatures is presented. Free- and macroscopic specific-volumes were measured by PALS and pressure-volume-temperature techniques, respectively. An analysis of the relation existing between macro- and nano-scales of the thermosetting networks developed by the different chemical structures is shown. The result obtained indicates that the structure of the hardeners governs the packing of the molecular chains of the epoxy network.

  19. Role of Interface Charges on High-k Based Poly-Si and Metal Gate Nano-Scale MOSFETs

    Directory of Open Access Journals (Sweden)

    N. Shashank

    2011-01-01

    Full Text Available The characteristics of typical sub-100 nm high K gate dielectrics MOSFET with different gate materials are simulated by two dimensional device simulators (ATLAS and ATHENA. The impact of interface charges on the characteristics of Poly-Si and TiN metal gate MOSFETs are investigated. The simulation results shows that, at high interface charge densities, the devices with Poly-Si gate degrade much compared to metal gate MOSFET structures. Emphasis is given to study the mobility degradation which stands as a major hurdle with the implementation of high-k dielectrics in nano-scale devices. The advantages of using Watt model over other models for the extraction of channel mobility is also clearly explained. The performance of the high-k MOSFET with metal electrode and poly-silicon electrode is also compared for various interface state charges.

  20. Spin Coated Nano Scale PMMA Films for Organic Thin Film Transistors

    Science.gov (United States)

    Shekar, B. Chandar; Sathish, S.; Sengoden, R.

    Nano scale poly methyl methacrylate (PMMA) films are prepared by spin coating the solution of PMMA on to p-Si substrate. The thickness of the films coated is measured by Ellipsometry. The SA-XRD spectrum of the as grown and annealed films indicated the amorphous nature. The SEM analysis revealed no pinholes, pits and dendritic features on the surface. Both as grown and annealed films indicated smooth surface and amorphous structure. The capacitance-voltage (C-V) behaviour of the metal-insulator-semiconductor (MIS) structure with Al/PMMA/p-Si has been studied. The C-V behaviour carried out for various frequencies (f) ranging from 20 kHz to 1 MHz and for a bias voltage range of -20 V to +20 V. Both as grown and annealed films showed a small flat band voltage (VFB) shift towards the negative voltage. The small shift in the VFB observed may be due to charge traps and de-traps. The obtained C-V behaviour for as grown and annealed films indicated that as grown PMMA nano scale thin films do not have many defects such as voids and inhomogeneity etc. The observed C-V behavior, a very low shift in the flat band voltage (VFB 0); reasonably higher dielectric constant values; thermal stability up to 2800C; amorphous and smooth surface implies that nano scale thin PMMA film coated by spin coating could be used as an efficient dielectric layer in field effect organic thin film transistors (OTFTs).

  1. The need for nano-scale modeling in solid oxide fuel cells.

    Science.gov (United States)

    Ryan, E M; Recknagle, K P; Liu, W; Khaleel, M A

    2012-08-01

    Solid oxide fuel cells (SOFCs) are high temperature fuel cells, which are being developed for large scale and distributed power systems. SOFCs promise to provide cleaner, more efficient electricity than traditional fossil fuel burning power plants. Research over the last decade has improved the design and materials used in SOFCs to increase their performance and stability for long-term operation; however, there are still challenges for SOFC researchers to overcome before SOFCs can be considered competitive with traditional fossil fuel burning and renewable power systems. In particular degradation due to contaminants in the fuel and oxidant stream is a major challenge facing SOFCs. In this paper we discuss ongoing computational and experimental research into different degradation and design issues in SOFC electrodes. We focus on contaminants in gasified coal which cause electrochemical and structural degradation in the anode, and chromium poisoning which affects the electrochemistry of the cathode. Due to the complex microstructures and multi-physics of SOFCs, multi-scale computational modeling and experimental research is needed to understand the detailed physics behind different degradation mechanisms, the local conditions within the cell which facilitate degradation, and its effects on the overall SOFC performance. We will discuss computational modeling research of SOFCs at the macro-, meso- and nano-scales which is being used to investigate the performance and degradation of SOFCs. We will also discuss the need for a multi-scale modeling framework of SOFCs, and the application of computational and multi-scale modeling to several degradation issues in SOFCs.

  2. 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...

  3. Comparative structural biology of the genome: nano-scale imaging of single nucleus from different kingdoms reveals the common physicochemical property of chromatin with a 40 nm structural unit.

    Science.gov (United States)

    Kobori, Toshiro; Kodama, Mami; Hizume, Kohji; Yoshimura, Shige H; Ohtani, Toshio; Takeyasu, Kunio

    2006-01-01

    Genome function is closely linked to the higher-order chromatin structures. To reveal a structural basis for the interphase chromatin organization, the 'on-substrate' lysis procedure was applied to nuclei isolated from human HeLa cells, chicken erythrocyte cells and yeast Schizosaccharomyces pombe, which possessed different intrinsic properties of the genomes such as histone composition and inter-nucleosomal distance. The isolated nuclei on a coverslip were successively treated with a detergent and a high-salt solution to extract the nuclear membrane and the nucleoplasm, and therefore, atomic force microscopy (AFM) visualized the structural changes in response to the lysis procedure. After the nucleoplasm was extracted, AFM clarified that chromatin fibers, approximately 40 nm in width, were partially released out of the nuclei and that the other chromatin still remaining in the nuclei was composed of granular structures with diameter of 80-100 nm. Thus, these results suggest that the approximately 40 nm fiber would be a stable structural unit and fold the 80-100 nm granules into a one-step higher unit. A common mechanism could be implied regardless of the intrinsic properties of the eukaryotic genomes.

  4. "Nano" Scale Biosignatures and the Search for Extraterrestrial Life

    Science.gov (United States)

    Oehler, D. Z.; Robert, F.; Meibom, A.; Mostefaoui, S.; Selo, M.; Walter, M. R.; Sugitani, K.; Allwood, A.; Mimura, K.; Gibson, E. K.

    2008-01-01

    A critical step in the search for remnants of potential life forms on other planets lies in our ability to recognize indigenous fragments of ancient microbes preserved in some of Earth's oldest rocks. To this end, we are building a database of nano-scale chemical and morphological characteristics of some of Earth's oldest organic microfossils. We are primarily using the new technology of Nano-Secondary ion mass spectrometry (NanoSIMS) which provides in-situ, nano-scale elemental analysis of trace quantities of organic residues. The initial step was to characterize element composition of well-preserved, organic microfossils from the late Proterozoic (0.8 Ga) Bitter Springs Formation of Australia. Results from that work provide morphologic detail and nitrogen/carbon ratios that appear to reflect the well-established biological origin of these 0.8 Ga fossils.

  5. Dynamic contact angle at nano-scale: a unified view

    OpenAIRE

    Lukyanov, Alex V.; Likhtman, Alexei E.

    2016-01-01

    Generation of dynamic contact angle in the course of wetting is a fundamental phenomenon of nature. Dynamic wetting processes have a direct impact on flows at nano-scale, and therefore their understanding is exceptionally important to emerging technologies. Here, we reveal the microscopic mechanism of dynamic contact angle generation. It has been demonstrated using large-scale molecular dynamics simulations of bead-spring model fluids that the main cause of local contact angle variations is t...

  6. Nano-Scale Secondary Ion Mass Spectrometry - A new analytical tool in biogeochemistry and soil ecology

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, A M; Ritz, K; Nunan, N; Clode, P L; Pett-Ridge, J; Kilburn, M R; Murphy, D V; O' Donnell, A G; Stockdale, E A

    2006-10-18

    Soils are structurally heterogeneous across a wide range of spatio-temporal scales. Consequently, external environmental conditions do not have a uniform effect throughout the soil, resulting in a large diversity of micro-habitats. It has been suggested that soil function can be studied without explicit consideration of such fine detail, but recent research has indicated that the micro-scale distribution of organisms may be of importance for a mechanistic understanding of many soil functions. Due to a lack of techniques with adequate sensitivity for data collection at appropriate scales, the question 'How important are various soil processes acting at different scales for ecological function?' is challenging to answer. The nano-scale secondary ion mass spectrometer (NanoSIMS) represents the latest generation of ion microprobes which link high-resolution microscopy with isotopic analysis. The main advantage of NanoSIMS over other secondary ion mass spectrometers is the ability to operate at high mass resolution, whilst maintaining both excellent signal transmission and spatial resolution ({approx}50 nm). NanoSIMS has been used previously in studies focusing on presolar materials from meteorites, in material science, biology, geology and mineralogy. Recently, the potential of NanoSIMS as a new tool in the study of biophysical interfaces in soils has been demonstrated. This paper describes the principles of NanoSIMS and discusses the potential of this tool to contribute to the field of biogeochemistry and soil ecology. Practical considerations (sample size and preparation, simultaneous collection of isotopes, mass resolution, isobaric interference and quantification of the isotopes of interest) are discussed. Adequate sample preparation avoiding biases in the interpretation of NanoSIMS data due to artifacts and identification of regions-of interest are of most concerns in using NanoSIMS as a new tool in biogeochemistry and soil ecology. Finally, we review

  7. Materials and structures

    Science.gov (United States)

    Saito, Theodore T.; Langenbeck, Sharon L.; Al-Jamily, Ghanim; Arnold, Joe; Barbee, Troy; Coulter, Dan; Dolgin, Ben; Fichter, Buck; George, Patricia; Gorenstein, Paul

    1992-08-01

    Materials and structures technology covers a wide range of technical areas. Some of the most pertinent issues for the Astrotech 21 missions include dimensionally stable structural materials, advanced composites, dielectric coatings, optical metallic coatings for low scattered light applications, low scattered light surfaces, deployable and inflatable structures (including optical), support structures in 0-g and 1-g environments, cryogenic optics, optical blacks, contamination hardened surfaces, radiation hardened glasses and crystals, mono-metallic telescopes and instruments, and materials characterization. Some specific examples include low coefficients of thermal expansion (CTE) structures (0.01 ppm/K), lightweight thermally stable mirror materials, thermally stable optical assemblies, high reliability/accuracy (1 micron) deployable structures, and characterization of nanometer level behavior of materials/structures for interferometry concepts. Large filled-aperture concepts will require materials with CTE's of 10(exp 9) at 80 K, anti-contamination coatings, deployable and erectable structures, composite materials with CTE's less than 0.01 ppm/K and thermal hysteresis, 0.001 ppm/K. Gravitational detection systems such as LAGOS will require rigid/deployable structures, dimensionally stable components, lightweight materials with low conductivity, and high stability optics. The Materials and Structures panel addressed these issues and the relevance of the Astrotech 21 mission requirements by dividing materials and structures technology into five categories. These categories, the necessary development, and applicable mission/program development phasing are summarized. For each of these areas, technology assessments were made and development plans were defined.

  8. Writing to and reading from a nano-scale crossbar memory based on memristors

    Science.gov (United States)

    Vontobel, Pascal O.; Robinett, Warren; Kuekes, Philip J.; Stewart, Duncan R.; Straznicky, Joseph; Williams, R. Stanley

    2009-10-01

    We present a design study for a nano-scale crossbar memory system that uses memristors with symmetrical but highly nonlinear current-voltage characteristics as memory elements. The memory is non-volatile since the memristors retain their state when un-powered. In order to address the nano-wires that make up this nano-scale crossbar, we use two coded demultiplexers implemented using mixed-scale crossbars (in which CMOS-wires cross nano-wires and in which the crosspoint junctions have one-time configurable memristors). This memory system does not utilize the kind of devices (diodes or transistors) that are normally used to isolate the memory cell being written to and read from in conventional memories. Instead, special techniques are introduced to perform the writing and the reading operation reliably by taking advantage of the nonlinearity of the type of memristors used. After discussing both writing and reading strategies for our memory system in general, we focus on a 64 × 64 memory array and present simulation results that show the feasibility of these writing and reading procedures. Besides simulating the case where all device parameters assume exactly their nominal value, we also simulate the much more realistic case where the device parameters stray around their nominal value: we observe a degradation in margins, but writing and reading is still feasible. These simulation results are based on a device model for memristors derived from measurements of fabricated devices in nano-scale crossbars using Pt and Ti nano-wires and using oxygen-depleted TiO2 as the switching material.

  9. A nano-scale alignment method for imprint lithography

    Institute of Scientific and Technical Information of China (English)

    WANG Li; LU Bing-heng; DING Yu-cheng; QIU Zhi-hui; LIU Hong-zhong

    2006-01-01

    A novel nano-scale alignment technique based generated by two pairs of quadruple gratings on mold and wafer are optically projected onto two photo-detector arrays,alignment errors in the x and y directions.The experiment sensitive to relative displacement of the mold and wafer,and the alignment accuracy obtained in the x and y directions and in θare ±20 nm,±25 nm and ±1 μrad (3σ),respectively.They can meet the requirements of alignment accuracy for submicron imprint lithography.

  10. Bioinspired structural materials

    Science.gov (United States)

    Wegst, Ulrike G. K.; Bai, Hao; Saiz, Eduardo; Tomsia, Antoni P.; Ritchie, Robert O.

    2015-01-01

    Natural structural materials are built at ambient temperature from a fairly limited selection of components. They usually comprise hard and soft phases arranged in complex hierarchical architectures, with characteristic dimensions spanning from the nanoscale to the macroscale. The resulting materials are lightweight and often display unique combinations of strength and toughness, but have proven difficult to mimic synthetically. Here, we review the common design motifs of a range of natural structural materials, and discuss the difficulties associated with the design and fabrication of synthetic structures that mimic the structural and mechanical characteristics of their natural counterparts.

  11. Aspects of Characterisation of Thin Coating Adhesion at the Nano-Scale

    Institute of Scientific and Technical Information of China (English)

    Jisheng E; Aiyang Zhang; Ben D. Beake

    2002-01-01

    In response to current development of materials in nano-science,characterisation of thin coating adhesion on a nano-scale becomes one of the most important research areas,as new coatings get ever thinner and more technologically advanced. With a review of technology and mechanisms of evaluating the adhesion failure of coatings,three techniques,nano impact ,nano-scratch and nano-indentation techniques ,for charactering the adhesion of thin coatings on a nano scale are described.Results of charactering the adhesion faliure of thin coatings using three different techniques indicate that the nano-scratch and nano-indentation techniques are very useful tools ,particularly in charactering the performance of thin coatings under nano-abra sive wear conditions. However,results from these types of tests cannot be easily applied to predict the performance of coatings whose are subject to nano-erosive wear,cyclic nano-fatigue or multiple nano-impacts during service. Instead,results of the new dynamic testing technique ,impact technique ,are found to correlate well with the coating performance under fatigue conditions,precisely because the impact test more closely simulates the actual contact (adhesion failure and wear)conditions of thin coatings occurring in nano-erosive/nano-fatigue/nano-impact wear.

  12. Auxetic materials and structures

    CERN Document Server

    Lim, Teik-Cheng

    2015-01-01

    This book describes the fundamentals of the mechanics and design of auxetic solids and structures, which possess a negative Poisson’s ratio. It will benefit two groups of readers: (a) industry practitioners, such as product and structural designers, who need to control mechanical stress distributions using auxetic materials, and (b) academic researchers and students who intend to produce structures with unique mechanical and other physical properties using auxetic materials.

  13. Structural model for the first wall W-based material in ITER project

    Institute of Scientific and Technical Information of China (English)

    Dehua Xu; Xinkui He; Shuiquan Deng; Yong Zhao

    2014-01-01

    The preparation, characterization, and test of the first wall materials designed to be used in the fusion reactor have remained challenging problems in the material science. This work uses the first-principles method as implemented in the CASTEP package to study the influ-ences of the doped titanium carbide on the structural sta-bility of the W–TiC material. The calculated total energy and enthalpy have been used as criteria to judge the structural models built with consideration of symmetry. Our simulation indicates that the doped TiC tends to form its own domain up to the investigated nano-scale, which implies a possible phase separation. This result reveals the intrinsic reason for the composite nature of the W–TiC material and provides an explanation for the experimen-tally observed phase separation at the nano-scale. Our approach also sheds a light on explaining the enhancing effects of doped components on the durability, reliability, corrosion resistance, etc., in many special steels.

  14. Wear properties of H13 with micron scale and nano scale grains bionic units processed by laser remelting

    Science.gov (United States)

    Zhang, Peng; Zhou, Hong; Wang, Cheng-tao; Liu, Yan; Ren, Lu-quan

    2013-12-01

    By simulating the cuticles of some soil animals, a combination of soft part (untreated substrate) and hard part (laser remelting area) structure was designed on metal surface to get an improved performance. Different specimens were prepared which contained units with micro and nano scale grains. The microstructures were observed by environmental field emission scanning electron microscopy. X-ray diffraction was used to identify the phases. The results of these tests indicate that due to the rapid solidification condition in the water, nano scale grains have a high microhardness between 1300 and 1000 HV. Retained austenite was found in it. Some of them transform to martensite in block on ring wear test. Specimens with bionic unit have a better wear resistance. Especially, the units with nano grains bring a further enhancement. The alternate soft and hard in macroscopic (substrate and laser remelting area) and microscopic (austenite and martensite) structure played a key role in improving the H13 wear resistance.

  15. Intelligent Design of Nano-Scale Molecular Imaging Agents

    Directory of Open Access Journals (Sweden)

    Takeaki Ozawa

    2012-12-01

    Full Text Available Visual representation and quantification of biological processes at the cellular and subcellular levels within living subjects are gaining great interest in life science to address frontier issues in pathology and physiology. As intact living subjects do not emit any optical signature, visual representation usually exploits nano-scale imaging agents as the source of image contrast. Many imaging agents have been developed for this purpose, some of which exert nonspecific, passive, and physical interaction with a target. Current research interest in molecular imaging has mainly shifted to fabrication of smartly integrated, specific, and versatile agents that emit fluorescence or luminescence as an optical readout. These agents include luminescent quantum dots (QDs, biofunctional antibodies, and multifunctional nanoparticles. Furthermore, genetically encoded nano-imaging agents embedding fluorescent proteins or luciferases are now gaining popularity. These agents are generated by integrative design of the components, such as luciferase, flexible linker, and receptor to exert a specific on–off switching in the complex context of living subjects. In the present review, we provide an overview of the basic concepts, smart design, and practical contribution of recent nano-scale imaging agents, especially with respect to genetically encoded imaging agents.

  16. Controlling mechanical properties of bio-inspired hydrogels by modulating nano-scale, inter-polymeric junctions

    Directory of Open Access Journals (Sweden)

    Seonki Hong

    2014-06-01

    Full Text Available Quinone tanning is a well-characterized biochemical process found in invertebrates, which produce diverse materials from extremely hard tissues to soft water-resistant adhesives. Herein, we report new types of catecholamine PEG derivatives, PEG-NH-catechols that can utilize an expanded spectrum of catecholamine chemistry. The PEGs enable simultaneous participation of amine and catechol in quinone tanning crosslinking. The intermolecular reaction between PEG-NH-catechols forms a dramatic nano-scale junction resulting in enhancement of gelation kinetics and mechanical properties of PEG hydrogels compared to results obtained by using PEGs in the absence of amine groups. Therefore, the study provides new insight into designing new crosslinking chemistry for controlling nano-scale chemical reactions that can broaden unique properties of bulk hydrogels.

  17. Electrochemical performance of nano-scale β-Ni(OH)2 prepared at different transformations of pH value

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li; ZHANG Li-jun; HAN Xi-jiang; ZHANG Cui-fen

    2008-01-01

    The influence of transforming pH values on the electrochemical performance of nano-scale Ni(OH)2was analyzed. The measurement results of XRD indicate that the nano-scale Ni (OH)2 prepared at different transformations of pH value is β( Ⅱ )-phase with different crystal lattice parameters. Cyclic voltammograms (CV) and electrochemical impedance spectroscopy(EIS) measurement results show that transformations of pH value affect the proton diffusion coefficient (D) and charge-transfer resistance (Rct) of the material. The simu-lation of cell experiment shows that the sample prepared at a pH of 10. 1 exhibits the maximum specific capacity(327. 8 mAh/g) and higher discharge platform, the discharge performance of electrodes depends on both D and Rct, so the kinetics characteristics that electrodes reaction is controlled by both mass-transfer step and charge-transfer step are put forward.

  18. Synthesis and Characterization of Tb-incorporated Apatite Nano-scale Powders

    Institute of Scientific and Technical Information of China (English)

    L.J. Sun; P.F. Ni; D.G. Guo; C.Q. Fang; J. Wang; F. Yang; X.F. Huang; Y.Z. Hao; H. Zhu; K.W. Xu

    2012-01-01

    Nano-scale Tb-incorporated apatite (nano-Tb-AP) particles with different Tb contents (Tb/(Tb+Ca)) of 0%, 5%, 10% and 20% were synthesized through a simple wet chemical method in this study. The crystal structure, thermal stabilities, chemical groups, crystal morphologies and crystal sizes of the nano--Tb-AP particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM), respectively. It was found that lattice constants, particle sizes, crystalline and thermal stability varied with the doped Tb contents. With the increasing of Tb content, the lattice constants, particle size, length/diameter ratio, crystalline and thermal stability of nano-Tb-AP gradually decrease. Especially, almost all the 20%Tb-AP nano particles had been decomposed at 1200 ℃ while only a few of the decomposed products (β-TCP) were detected in the Tb-free nano apatite powders: This kind of nano-scale Tb-incorporated apatite exhibits an extremely potential clinic application because it integrates both the excellent biological functions of Tb element and apatite in human body.

  19. Prepare dispersed CIS nano-scale particles and spray coating CIS absorber layers using nano-scale precursors.

    Science.gov (United States)

    Liou, Jian-Chiun; Diao, Chien-Chen; Lin, Jing-Jenn; Chen, Yen-Lin; Yang, Cheng-Fu

    2014-01-01

    In this study, the Mo-electrode thin films were deposited by a two-stepped process, and the high-purity copper indium selenide-based powder (CuInSe2, CIS) was fabricated by hydrothermal process by Nanowin Technology Co. Ltd. From the X-ray pattern of the CIS precursor, the mainly crystalline phase was CIS, and the almost undetectable CuSe phase was observed. Because the CIS powder was aggregated into micro-scale particles and the average particle sizes were approximately 3 to 8 μm, the CIS power was ground into nano-scale particles, then the 6 wt.% CIS particles were dispersed into isopropyl alcohol to get the solution for spray coating method. Then, 0.1 ml CIS solution was sprayed on the 20 mm × 10 mm Mo/glass substrates, and the heat treatment for the nano-scale CIS solution under various parameters was carried out in a selenization furnace. The annealing temperature was set at 550°C, and the annealing time was changed from 5 to 30 min, without extra Se content was added in the furnace. The influences of annealing time on the densification, crystallization, resistivity (ρ), hall mobility (μ), and carrier concentration of the CIS absorber layers were well investigated in this study.

  20. Density functional theory studies on the nano-scaled composites consisted of graphene and acyl hydrazone molecules

    Science.gov (United States)

    Ren, J. L.; Zhou, L.; Lv, Z. C.; Ding, C. H.; Wu, Y. H.; Bai, H. C.

    2016-07-01

    Graphene, which is the first obtained single atomic layer 2D materials, has drawn a great of concern in nano biotechnology due to the unique property. On one hand, acyl hydrazone compounds belonging to the Schif bases have aroused considerable attention in medicine, pharmacy, and analytical reagent. However, few understanding about the interaction between graphene and acyl hydrazone molecules is now available. And such investigations are much crucial for the applications of these new nano-scaled composites. The current work revealed theoretical investigations on the nano-scaled composites built by acyl hydrazone molecules loaded on the surface of graphene. The relative energy, electronic property and the interaction between the counterparts of graphene/acyl hydrazone composites are investigated based on the density functional theory calculations. According to the obtained adsorption energy, the formation of the nano-scaled composite from the isolated graphene and acyl hydrazone molecule is exothermic, and thus it is energetically favorable to form these nano composites in viewpoint of total energy change. The frontier molecular orbital for the nano composite is mainly distributed at the graphene part, leading to that the energy levels of the frontier molecular orbital of the nano composites are very close to that of isolated graphene. Moreover, the counterpart interaction for the graphene/acyl hydrazone composites is also explored based on the discussions of orbital hybridization, charge redistribution and Van der Waals interaction.

  1. Effect of transformation pH on performance of nano-scale β-Ni(OH)2

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li; WANG Shou-jun; SHENG Jun; HAN Xi-jiang

    2007-01-01

    The influence of transformation pH value on the performance of nano-scale Ni(OH)2 was analyzed. The measurement results of XRD and TEM indicate that the samples are composed of β-Ni(OH)2 with crystal size of 20-50 nm, and the crystal lattice parameters of nano-scale Ni(OH)2 prepared at different transformation pH values are different. With the increase of transformation pH value, the agglomeration of nano-scale Ni(OH)2 becomes obvious. Cyclic voltammograms(CV) and electrochemical impedance spectroscopy(EIS) measurement results show that transformation pH value affects the proton diffusion coefficient(D) and charge-transfer resistance(Rct) of the material. The specific capacity is up to 327.8 mA-h/g, and the discharge performance of electrodes depends on both D and Rct, so the kinetic characteristics that electrodes reaction is controlled by both mass-transfer step and charge-transfer step was put forward.

  2. Phy-chemical Attributes of Nano-scale V2O5/TiO2 Catalyst and Its’ Effect on Soot Oxidation

    OpenAIRE

    Deqing Mei; Lichang Li; Chen Zhu; Xiang Zhao; Yinnan Yuan

    2016-01-01

    The V2O5 catalysts which supported on nano-scale TiO2 with variation of vanadium contents (5%, 10%, 20% and 40%) were prepared by an incipient-wetness impregnation method. The phase structures of nano-scale V2O5/TiO2 catalysts with different loading rates were characterized by Scanning electron microscope (SEM), X-Ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectra. The oxidation activities of catalysts over diesel soot were performed in a themogravimetric analysis (TGA) syst...

  3. Modeling and simulation of electronic structure, material interface and random doping in nano electronic devices

    Science.gov (United States)

    Chen, Duan; Wei, Guo-Wei

    2010-01-01

    The miniaturization of nano-scale electronic devices, such as metal oxide semiconductor field effect transistors (MOSFETs), has given rise to a pressing demand in the new theoretical understanding and practical tactic for dealing with quantum mechanical effects in integrated circuits. Modeling and simulation of this class of problems have emerged as an important topic in applied and computational mathematics. This work presents mathematical models and computational algorithms for the simulation of nano-scale MOSFETs. We introduce a unified two-scale energy functional to describe the electrons and the continuum electrostatic potential of the nano-electronic device. This framework enables us to put microscopic and macroscopic descriptions in an equal footing at nano scale. By optimization of the energy functional, we derive consistently-coupled Poisson-Kohn-Sham equations. Additionally, layered structures are crucial to the electrostatic and transport properties of nano transistors. A material interface model is proposed for more accurate description of the electrostatics governed by the Poisson equation. Finally, a new individual dopant model that utilizes the Dirac delta function is proposed to understand the random doping effect in nano electronic devices. Two mathematical algorithms, the matched interface and boundary (MIB) method and the Dirichlet-to-Neumann mapping (DNM) technique, are introduced to improve the computational efficiency of nano-device simulations. Electronic structures are computed via subband decomposition and the transport properties, such as the I-V curves and electron density, are evaluated via the non-equilibrium Green's functions (NEGF) formalism. Two distinct device configurations, a double-gate MOSFET and a four-gate MOSFET, are considered in our three-dimensional numerical simulations. For these devices, the current fluctuation and voltage threshold lowering effect induced by the discrete dopant model are explored. Numerical convergence

  4. Modeling and simulation of electronic structure, material interface and random doping in nano-electronic devices

    Science.gov (United States)

    Chen, Duan; Wei, Guo-Wei

    2010-06-01

    The miniaturization of nano-scale electronic devices, such as metal oxide semiconductor field effect transistors (MOSFETs), has given rise to a pressing demand in the new theoretical understanding and practical tactic for dealing with quantum mechanical effects in integrated circuits. Modeling and simulation of this class of problems have emerged as an important topic in applied and computational mathematics. This work presents mathematical models and computational algorithms for the simulation of nano-scale MOSFETs. We introduce a unified two-scale energy functional to describe the electrons and the continuum electrostatic potential of the nano-electronic device. This framework enables us to put microscopic and macroscopic descriptions in an equal footing at nano-scale. By optimization of the energy functional, we derive consistently coupled Poisson-Kohn-Sham equations. Additionally, layered structures are crucial to the electrostatic and transport properties of nano-transistors. A material interface model is proposed for more accurate description of the electrostatics governed by the Poisson equation. Finally, a new individual dopant model that utilizes the Dirac delta function is proposed to understand the random doping effect in nano-electronic devices. Two mathematical algorithms, the matched interface and boundary (MIB) method and the Dirichlet-to-Neumann mapping (DNM) technique, are introduced to improve the computational efficiency of nano-device simulations. Electronic structures are computed via subband decomposition and the transport properties, such as the I- V curves and electron density, are evaluated via the non-equilibrium Green's functions (NEGF) formalism. Two distinct device configurations, a double-gate MOSFET and a four-gate MOSFET, are considered in our three-dimensional numerical simulations. For these devices, the current fluctuation and voltage threshold lowering effect induced by the discrete dopant model are explored. Numerical

  5. Ultra-fast nano-scale phase transitions in systems driven far from equilibrium

    Science.gov (United States)

    Caro, A.; Lopasso, E. M.; Caro, M.; Turchi, P. E. A.

    2004-03-01

    We study the thermodynamic forces acting on the evolution of the nanoscale regions excited by laser shots into solid targets. We analyze the role of diffusion, thermo-migration, and the liquidus-solidus two-phase field crossing, as the system cools down from the induced melt under different conditions of energy deposition. To determine the relevance of these thermodynamic forces, solute redistribution is evaluated using molecular dynamics simulations of equilibrium Au-Ni solid solutions. Our results show the combined effects of thermo-migration and solute redistribution that, depending on the material, can reinforce or cancel each other. These effects show that the combination of ultra-fast but nano-scale characteristics of these processes can be used to produce nanoscale modifications of composition in alloys

  6. Low-temperature method of producing nano-scaled graphene platelets and their nanocomposites

    Science.gov (United States)

    Zhamu, Aruna [Centerville, OH; Shi, Jinjun [Columbus, OH; Guo, Jiusheng [Centerville, OH; Jang, Bor Z [Centerville, OH

    2012-03-13

    A method of exfoliating a layered material to produce separated nano-scaled platelets having a thickness smaller than 100 nm. The method comprises: (a) providing a graphite intercalation compound comprising a layered graphite containing expandable species residing in an interlayer space of the layered graphite; (b) exposing the graphite intercalation compound to an exfoliation temperature lower than 650.degree. C. for a duration of time sufficient to at least partially exfoliate the layered graphite without incurring a significant level of oxidation; and (c) subjecting the at least partially exfoliated graphite to a mechanical shearing treatment to produce separated platelets. The method can further include a step of dispersing the platelets in a polymer or monomer solution or suspension as a precursor step to nanocomposite fabrication.

  7. Nano-scale machining of polycrystalline coppers - effects of grain size and machining parameters.

    Science.gov (United States)

    Shi, Jing; Wang, Yachao; Yang, Xiaoping

    2013-11-22

    In this study, a comprehensive investigation on nano-scale machining of polycrystalline copper structures is carried out by molecular dynamics (MD) simulation. Simulation cases are constructed to study the impacts of grain size, as well as various machining parameters. Six polycrystalline copper structures are produced, which have the corresponding equivalent grain sizes of 5.32, 6.70, 8.44, 13.40, 14.75, and 16.88 nm, respectively. Three levels of depth of cut, machining speed, and tool rake angle are also considered. The results show that greater cutting forces are required in nano-scale polycrystalline machining with the increase of depth of cut, machining speed, and the use of the negative tool rake angles. The distributions of equivalent stress are consistent with the cutting force trends. Moreover, it is discovered that in the grain size range of 5.32 to 14.75 nm, the cutting forces and equivalent stress increase with the increase of grain size for the nano-structured copper, while the trends reserve after the grain size becomes even higher. This discovery confirms the existence of both the regular Hall-Petch relation and the inverse Hall-Petch relation in polycrystalline machining, and the existence of a threshold grain size allows one of the two relations to become dominant. The dislocation-grain boundary interaction shows that the resistance of the grain boundary to dislocation movement is the fundamental mechanism of the Hall-Petch relation, while grain boundary diffusion and movement is the reason of the inverse Hall-Petch relation.

  8. Nanocellulose as a sustainable biomass material: structure, properties, present status and future prospects in biomedical applications.

    Science.gov (United States)

    Xue, Yan; Mou, Zihao; Xiao, Huining

    2017-10-02

    Nanocellulose, extracted from the most abundant biomass material cellulose, has proved to be an environmentally friendly material with excellent mechanical performance owing to its unique nano-scaled structure, and has been used in a variety of applications as engineering and functional materials. The great biocompatibility and biodegradability, in particular, render nanocellulose promising in biomedical applications. In this review, the structure, treatment technology and properties of three different nanocellulose categories, i.e., nanofibrillated cellulose (NFC), nanocrystalline cellulose (NCC) and bacterial nanocellulose (BNC), are introduced and compared. The cytotoxicity, biocompatibility and frontier applications in biomedicine of the three nanocellulose categories were the focus and are detailed in each section. Future prospects concerning the cytotoxicity, applications and industrial production of nanocellulose are also discussed in the last section.

  9. Nano-scale electron bunching in laser-triggered ionization injection in plasma accelerators

    CERN Document Server

    Xu, X L; Li, F; Wan, Y; Wu, Y P; Hua, J F; Pai, C -H; Lu, W; An, W; Yu, P; Mori, W B; Joshi, C

    2015-01-01

    Ionization injection is attractive as a controllable injection scheme for generating high quality electron beams using plasma-based wakefield acceleration. Due to the phase dependent tunneling ionization rate and the trapping dynamics within a nonlinear wake, the discrete injection of electrons within the wake is nonlinearly mapped to discrete final phase space structure of the beam at the location where the electrons are trapped. This phenomenon is theoretically analyzed and examined by three-dimensional particle-in-cell simulations which show that three dimensional effects limit the wave number of the modulation to between $> 2k_0$ and about $5k_0$, where $k_0$ is the wavenumber of the injection laser. Such a nano-scale bunched beam can be diagnosed through coherent transition radiation upon its exit from the plasma and may find use in generating high-power ultraviolet radiation upon passage through a resonant undulator.

  10. Line edge roughness induced threshold voltage variability in nano-scale FinFETs

    Science.gov (United States)

    Rathore, Rituraj Singh; Sharma, Rajneesh; Rana, Ashwani K.

    2017-03-01

    In aggressively scaled devices, the FinFET technology has become more prone to line edge roughness (LER) induced threshold voltage variability. As a result, nano scale FinFET structures face the problem of intrinsic statistical fluctuations in the threshold voltage. This paper describes the all LER induced variability of threshold voltage for 14 nm underlap FinFET using 3-D numerical simulations. It is concluded that percentage threshold voltage (VTH) fluctuations referenced with respect to rectangular FinFET can go up to 8.76%. This work has also investigated the impact of other sources of variability such as random dopant fluctuation, work function variation and oxide thickness variation on threshold voltage.

  11. Structure - materials - production

    DEFF Research Database (Denmark)

    Gammelgaard Nielsen, Anders; Gammel, Peder; Busch, Jens

    2002-01-01

    For the last six years th Aarhus School of Architecture has introduced the first year students (there are about 200 students admitted each year) to structure, materials, design and production through a five week course in collaboration with a group of local companies....

  12. GaN nanowire tip for high aspect ratio nano-scale AFM metrology (Conference Presentation)

    Science.gov (United States)

    Behzadirad, Mahmoud; Dawson, Noel; Nami, Mohsen; Rishinaramangalam, Ashwin K.; Feezell, Daniel F.; Busani, Tito L.

    2016-09-01

    In this study we introduce Gallium Nitride (GaN) nanowire (NW) as high aspect ratio tip with excellent durability for nano-scale metrology. GaN NWs have superior mechanical property and young modulus compare to commercial Si and Carbon tips which results in having less bending issue during measurement. The GaN NWs are prepared via two different methods: i) Catalyst-free selected area growth, using Metal Organic Chemical Vapor Deposition (MOCVD), ii) top-down approach by employing Au nanoparticles as the mask material in dry-etch process. To achieve small diameter tips, the semipolar planes of the NWs grown by MOCVD are etched using AZ400k. The diameter of the NWs fabricated using the top down process is controlled by using different size of nanoparticles and by Inductively Coupled Plasma etching. NWs with various diameters were manipulated on Si cantilevers using Focus Ion Beam (FIB) to make tips for AFM measurement. A Si (110) substrate containing nano-scale grooves with vertical 900 walls were used as a sample for inspection. AFM measurements were carried out in tapping modes for both types of nanowires (top-down and bottom-up grown nanowires) and results are compared with conventional Si and carbon nanotube tips. It is shown our fabricated tips are robust and have improved edge resolution over conventional Si tips. GaN tips made with NW's fabricated using our top down method are also shown to retain the gold nanoparticle at tip, which showed enhanced field effects in Raman spectroscopy.

  13. Nano-scale processes behind ion-beam cancer therapy

    Science.gov (United States)

    Surdutovich, Eugene; Garcia, Gustavo; Mason, Nigel; Solov'yov, Andrey V.

    2016-04-01

    This topical issue collates a series of papers based on new data reported at the third Nano-IBCT Conference of the COST Action MP1002: Nanoscale Insights into Ion Beam Cancer Therapy, held in Boppard, Germany, from October 27th to October 31st, 2014. The Nano-IBCT COST Action was launched in December 2010 and brought together more than 300 experts from different disciplines (physics, chemistry, biology) with specialists in radiation damage of biological matter from hadron-therapy centres, and medical institutions. This meeting followed the first and the second conferences of the Action held in October 2011 in Caen, France and in May 2013 in Sopot, Poland respectively. This conference series provided a focus for the European research community and has highlighted the pioneering research into the fundamental processes underpinning ion beam cancer therapy. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey V. Solov'yov, Nigel Mason, Gustavo Garcia and Eugene Surdutovich.

  14. Structural and Material Instability

    DEFF Research Database (Denmark)

    Cifuentes, Gustavo Cifuentes

    This work is a small contribution to the general problem of structural and material instability. In this work, the main subject is the analysis of cracking and failure of structural elements made from quasi-brittle materials like concrete. The analysis is made using the finite element method. Three...... use of interface elements) is used successfully to model cases where the path of the discontinuity is known in advance, as is the case of the analysis of pull-out of fibers embedded in a concrete matrix. This method is applied to the case of non-straight fibers and fibers with forces that have....... Numerical problems associated with the use of elements with embedded cracks based on the extended finite element method are presented in the next part of this work. And an alternative procedure is used in order to successfully remove these numerical problems. In the final part of this work, a computer...

  15. Nano-scale CMOS analog circuits models and CAD techniques for high-level design

    CERN Document Server

    Pandit, Soumya; Patra, Amit

    2014-01-01

    Reliability concerns and the limitations of process technology can sometimes restrict the innovation process involved in designing nano-scale analog circuits. The success of nano-scale analog circuit design requires repeat experimentation, correct analysis of the device physics, process technology, and adequate use of the knowledge database.Starting with the basics, Nano-Scale CMOS Analog Circuits: Models and CAD Techniques for High-Level Design introduces the essential fundamental concepts for designing analog circuits with optimal performances. This book explains the links between the physic

  16. Method of producing nano-scaled graphene and inorganic platelets and their nanocomposites

    Science.gov (United States)

    Jang, Bor Z.; Zhamu, Aruna

    2011-02-22

    Disclosed is a method of exfoliating a layered material (e.g., graphite and graphite oxide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm, and often between 0.34 nm and 1.02 nm. The method comprises: (a) subjecting the layered material in a powder form to a halogen vapor at a first temperature above the melting point or sublimation point of the halogen at a sufficient vapor pressure and for a duration of time sufficient to cause the halogen molecules to penetrate an interlayer space of the layered material, forming a stable halogen-intercalated compound; and (b) heating the halogen-intercalated compound at a second temperature above the boiling point of the halogen, allowing halogen atoms or molecules residing in the interlayer space to exfoliate the layered material to produce the platelets. Alternatively, rather than heating, step (a) is followed by a step of dispersing the halogen-intercalated compound in a liquid medium which is subjected to ultrasonication for exfoliating the halogen-intercalated compound to produce the platelets, which are dispersed in the liquid medium. The halogen can be readily captured and re-used, thereby significantly reducing the impact of halogen to the environment. The method can further include a step of dispersing the platelets in a polymer or monomer solution or suspension as a precursor step to nanocomposite fabrication.

  17. Micro- and nano-scale optoelectronic devices using vanadium dioxide

    Science.gov (United States)

    Joushaghani, Arash

    Miniaturization has the potential to reduce the size, cost, and power requirements of active optical devices. However, implementing (sub)wavelength-scale electro-optic switches with high efficiency, low insertion loss, and high extinction ratios remains challenging due to their small active volumes. Here, we use the insulator-metal phase transition of vanadium dioxide (VO2), which exhibits a large and reversible change in the refractive index across the phase transition to demonstrate compact, broadband, and efficient switches and photodetectors with record-setting characteristics. We begin by analyzing the electrical and optical properties of VO2 thin films across the phase transition and discuss the fabrication processes that yield micron- and nano-scale VO2 devices. We then demonstrate a surface plasmon thermo-optic switch, which achieves an extinction ratio of 10 dB in a 5 um long device, a record for plasmonic devices. The switch operates over a 100 nm optical bandwidth, and exhibits a thermally limited switching time of 40 mus. We investigate the current and voltage induced switching of VO2 in nano-gap junctions and show optical switching times as short as 20 ns. The two terminal VO2 junctions are incorporated in a silicon photonics platform to yield silicon-VO2 hybrid waveguide devices with a record extinction ratio of 12 dB in a 1 mum long device. In photodetector mode, the devices exhibit a nonlinear responsivity greater than 12 A/W for optical powers less than 1 muW. This device is the smallest electrically controlled and integrated switch and photodetector capable of achieving extinction ratios > 10 dB/mum. We finally investigate the ultra-fast thermal heating in gold nano-apertures and demonstrate that electron heating can change the gold lattice temperature by 300 K in tens of picoseconds. These nano-apertures can be hybridized with VO2 to demonstrate high extinction and ultrafast optical switches.

  18. Nano-scaled semiconductor devices physics, modelling, characterisation, and societal impact

    CERN Document Server

    Gutiérrez-D, Edmundo A

    2016-01-01

    This book describes methods for the characterisation, modelling, and simulation prediction of these second order effects in order to optimise performance, energy efficiency and new uses of nano-scaled semiconductor devices.

  19. Treatment of distillery wastewater by the nano-scale zero-valent iron and the supported nano-scale zero-valent iron.

    Science.gov (United States)

    Homhoul, Phatkanok; Pengpanich, Sitthiphong; Hunsom, Mali

    2011-01-01

    The treatment of wastewater from the distillery industry was carried out by using nano-scale- and supported nano-scale zero-valent iron at a laboratory scale and ambient temperature. Effects of dilution, pH, mixing rate, zero-valent iron dosage, and amount of support for the zero-valent iron were investigated. All parameters had a significant effect on the removal efficiency of all investigated pollutants. Increasing the number of dilutions and the nano-scale zero-valent iron dosage led to the increase of removal efficiency of pollutants. Higher removal efficiency was achieved in an acidic initial pH of wastewater. The reduction of all pollutants was limited by the kinetics of the pollutant destruction/reduction by nano-scale zero-valent iron particles at a mixing rate greater than 170 rpm. At optimum condition, greater than 95, 94, and 64% of color, chemical oxygen demand, and biochemical oxygen demand were removed, respectively, within 6 hours. Additionally, the presence of a support had a significant effect on pollutant removal.

  20. Cooperative Research Alliance Multiscale Modeling of Electronic Materials (MSME)

    Science.gov (United States)

    2010-11-19

    transport characterization in nano-scale structures DC-40GHz environmental cryogenic I/V probe station Spectral dissection of bacteria and thin-films...Sensors and actuators for microrobots Graphene Flexible Displays Family of UGS Compact Radar Carbon Nanotubes Environmental Sensing Reformed...simulations • Develop innovative experimentation & validation techniques • Define multiscale material metrics • Perform processing & synthesis Multi

  1. Nano Scale Mechanical Analysis of Biomaterials Using Atomic Force Microscopy

    Science.gov (United States)

    Dutta, Diganta

    The atomic force microscope (AFM) is a probe-based microscope that uses nanoscale and structural imaging where high resolution is desired. AFM has also been used in mechanical, electrical, and thermal engineering applications. This unique technique provides vital local material properties like the modulus of elasticity, hardness, surface potential, Hamaker constant, and the surface charge density from force versus displacement curve. Therefore, AFM was used to measure both the diameter and mechanical properties of the collagen nanostraws in human costal cartilage. Human costal cartilage forms a bridge between the sternum and bony ribs. The chest wall of some humans is deformed due to defective costal cartilage. However, costal cartilage is less studied compared to load bearing cartilage. Results show that there is a difference between chemical fixation and non-chemical fixation treatments. Our findings imply that the patients' chest wall is mechanically weak and protein deposition is abnormal. This may impact the nanostraws' ability to facilitate fluid flow between the ribs and the sternum. At present, AFM is the only tool for imaging cells' ultra-structure at the nanometer scale because cells are not homogeneous. The first layer of the cell is called the cell membrane, and the layer under it is made of the cytoskeleton. Cancerous cells are different from normal cells in term of cell growth, mechanical properties, and ultra-structure. Here, force is measured with very high sensitivity and this is accomplished with highly sensitive probes such as a nano-probe. We performed experiments to determine ultra-structural differences that emerge when such cancerous cells are subject to treatments such as with drugs and electric pulses. Jurkat cells are cancerous cells. These cells were pulsed at different conditions. Pulsed and non-pulsed Jurkat cell ultra-structures were investigated at the nano meter scale using AFM. Jurkat cell mechanical properties were measured under

  2. Inkjet-based deposition of polymer thin films enabled by a lubrication model incorporating nano-scale parasitics

    Science.gov (United States)

    Singhal, Shrawan; Meissl, Mario J.; Bonnecaze, Roger T.; Sreenivasan, S. V.

    2013-09-01

    Thin film lubrication theory has been widely used to model multi-scale fluid phenomena. Variations of the same have also found application in fluid-based manufacturing process steps for micro- and nano-scale devices over large areas where a natural disparity in length scales exists. Here, a novel inkjet material deposition approach has been enabled by an enhanced thin film lubrication theory that accounts for nano-scale substrate parasitics. This approach includes fluid interactions with a thin flexible superstrate towards a new process called Jet and Coat of Thin-films (JCT). Numerical solutions of the model have been verified, and also validated against controlled experiments of polymer film deposition with good agreement. Understanding gleaned from the experimentally validated model has then been used to facilitate JCT process synthesis resulting in substantial reduction in the influence of parasitics and a concomitant improvement in the film thickness uniformity. Polymer films ranging from 20 to 500 nm mean thickness have been demonstrated with standard deviation of less than 2% of the mean film thickness. The JCT process offers advantages over spin coating which is not compatible with roll-to-roll processing and large area processing for displays. It also improves over techniques such as knife edge coating, slot die coating, as they are limited in the range of thicknesses of films that can be deposited without compromising uniformity.

  3. Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes.

    Science.gov (United States)

    Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi

    2017-05-23

    This work describes the measurement procedure and principles of a sampling moiré technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moiré method or the spatial phase-shifting sampling moiré method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moiré fringes are generated to reconstruct a multiplication moiré pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moiré method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moiré fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moiré techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

  4. Performance characteristic of a Stirling refrigeration cycle in micro/nano scale

    Science.gov (United States)

    Nie, Wenjie; He, Jizhou; Du, Jianqiang

    2009-02-01

    The aim of the paper is to present the performance characteristics of a Stirling refrigeration cycle in micro/nano scale, in which the working substance of cycle is an ideal Maxwellian gas. Due to the quantum boundary effect on the gas particles confined in the finite domain, the cycle no longer possesses the condition of perfect regeneration. The inherent regenerative losses, the refrigeration heat and coefficient of performance (COP) of the cycle are derived. It is found that, for the micro/nano scaled Stirling refrigeration cycle devices, the refrigeration heat and COP of cycle all depend on the surface area of the system (boundary of cycle) besides the temperature of the heat reservoirs, the volume of system and other parameters, while for the macro scaled refrigeration cycle devices, the refrigeration heat and COP of cycle are independent of the surface area of the system. Variations of the refrigeration heat ratio rR and the COP ratio rε with the temperature ratio τ and volume ratio rV for the different surface area ratio rA are examined, which reveals the influence of the boundary of cycle on the performance of a micro/nano scaled Stirling refrigeration cycle. The results are useful for designing of a micro/nano scaled Stirling cycle device and may conduce to confirming experimentally the quantum boundary effect in the micro/nano scaled devices.

  5. Nonreciprocal lasing and polarization selectivity in silicon ring Raman lasers based on micro- and nano-scale waveguides

    Science.gov (United States)

    Vermeulen, N.

    2012-06-01

    In this paper I present a generic model that describes the lasing characteristics of continuous-wave circular and racetrack-shaped ring Raman lasers based on micro- and nano-scale silicon waveguides, including their lasing directionality and polarization behavior. This model explicitly takes into account the effective Raman gain values for forward and backward lasing, the Raman amplification in the bus waveguide, and the spatial gain variations for different polarization states in the ring structure. I show numerically that ring lasers based on micro-scale waveguides generate unidirectional lasing in either the forward or backward direction because of an asymmetry in nonlinear losses at near-infrared telecommunication wavelengths, whereas those based on nanowires yield only backward lasing due to a non-reciprocity in effective gain. Furthermore, the model indicates that backward lasing can yield a significantly higher lasing output at the bus waveguide facets than lasing in the forward direction. Finally, considering a TE-polarized pump input for a (100) grown silicon ring Raman laser, I demonstrate numerically that the polarization state of the lasing radiation strongly depends on whether micro-scale or nano-scale waveguides are used.

  6. Observation of multiple superconducting gaps in Fe1+yTe1-xSex via a nano-scale approach to point-contact spectroscopy

    OpenAIRE

    Peng, Haibing; De, Debtanu; Wu, Zheng; Diaz-Pinto, Carlos

    2012-01-01

    We report a distinct experimental approach to point-contact Andreev reflection spectroscopy with diagnostic capability via a unique design of nano-scale normal metal/superconductor devices with excellent thermo-mechanical stability, and have employed this method to unveil the existence of two superconducting energy gaps in iron chalcogenide Fe1+yTe1-xSex which is crucial for understanding its pairing mechanism. This work opens up new opportunities to study gap structures in superconductors an...

  7. Droplets and the three-phase contact line at the nano-scale. Statics and dynamics

    Science.gov (United States)

    Yatsyshin, Petr; Sibley, David; Savva, Nikos; Kalliadasis, Serafim

    2014-11-01

    Understanding the behaviour of the solid-liquid-vapour contact line at the scale of several tens of molecular diameters is important in wetting hydrodynamics with applications in micro- and nano-fluidics, including the design of lab-on-a-chip devices and surfaces with specific wetting properties. Due to the fluid inhomogeneity at the nano-scale, the application of continuum-mechanical approaches is limited, and a natural way to remedy this is to seek descriptions accounting for the non-local molecular-level interactions. Density Functional Theory (DFT) for fluids offers a statistical-mechanical framework based on expressing the free energy of the fluid-solid pair as a functional of the spatially varying fluid density. DFT allows us to investigate small drops deposited on planar substrates whilst keeping track of the microscopic structural details of the fluid. Starting from a model of intermolecular forces, we systematically obtain interfaces, surface tensions, and the microscopic contact angle. Using a dynamic extension of equilibrium DFT, we investigate the diffusion-driven evolution of the three-phase contact line to gain insight into the dynamic behaviour of the microscopic contact angle, which is still under debate.

  8. Dynamic hydrophobicity of heterogeneous pillared surfaces at the nano-scale

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Tae Woo; Ha, Man Yeong; Jang, Joon Kyoung [Pusan National University, Busan (Korea, Republic of); Ambrosia, Matthew Stanley [Catholic University of Pusan, Busan (Korea, Republic of)

    2015-04-15

    In this study, the static and dynamic behaviors of nano-scale water droplets on heterogeneous surfaces were investigated using molecular dynamics simulations. The surface consisted of a flat plate and pillar structures. The surface was designed with four pillar heights and three pillar characteristic energies. Simulations were first run so that the water droplet reached the static equilibrium state. Once the static water droplets were in Cassie-Baxter state, increasing the pillar height had very little effect on the contact angle. Droplets on the surface with the strongest pillar characteristic energy never reached the Cassie-Baxter state and contact angles tended to decrease with increasing pillar height. Then five forces were applied to the water droplets parallel to the surface to observe the dynamic behavior of the droplets. Then, the effect of the pillar characteristic energy on the behavior of the dynamic water droplet was discussed using the contact angle hysteresis ( cosθ{sub Re} - cosθ{sub Ad}) as the pillar height and the magnitude of the applied force varied. When compared to the homogeneous cases, it was found that except at the lowest pillar height all of the lower pillar characteristic energy cases were hydrophobic and did not depend much on pillar height or magnitude of force. Whereas the higher pillar characteristic energy cases were generally hydrophilic and the hydrophobicity depended greatly on the magnitude of the force.

  9. High-Bandwidth Dynamic Full-Field Profilometry for Nano-Scale Characterization of MEMS

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L-C [Graduate Institute of Automation Technology, National Taipei University of Technology, 1 Sec. 3 Chung-Hsiao East Rd., Taipei, 106, Taiwan (China); Huang, Y-T [Graduate Institute of Automation Technology, National Taipei University of Technology, 1 Sec. 3 Chung-Hsiao East Rd., Taipei, 106, Taiwan (China); Chang, P-B [Graduate Institute of Mechanical and Electrical Engineering, National Taipei University of Technology, 1 Sec. 3 Chung-Hsiao East Rd., Taipei, 106, Taiwan (China)

    2006-10-15

    The article describes an innovative optical interferometric methodology to delivery dynamic surface profilometry with a measurement bandwidth up to 10MHz or higher and a vertical resolution up to 1 nm. Previous work using stroboscopic microscopic interferometry for dynamic characterization of micro (opto)electromechanical systems (M(O)EMS) has been limited in measurement bandwidth mainly within a couple of MHz. For high resonant mode analysis, the stroboscopic light pulse is insufficiently short to capture the moving fringes from dynamic motion of the detected structure. In view of this need, a microscopic prototype based on white-light stroboscopic interferometry with an innovative light superposition strategy was developed to achieve dynamic full-field profilometry with a high measurement bandwidth up to 10MHz or higher. The system primarily consists of an optical microscope, on which a Mirau interferometric objective embedded with a piezoelectric vertical translator, a high-power LED light module with dual operation modes and light synchronizing electronics unit are integrated. A micro cantilever beam used in AFM was measured to verify the system capability in accurate characterisation of dynamic behaviours of the device. The full-field seventh-mode vibration at a vibratory frequency of 3.7MHz can be fully characterized and nano-scale vertical measurement resolution as well as tens micrometers of vertical measurement range can be performed.

  10. Three-dimensional phase segregation of micro-porous layers for fuel cells by nano-scale X-ray computed tomography

    Science.gov (United States)

    Andisheh-Tadbir, Mehdi; Orfino, Francesco P.; Kjeang, Erik

    2016-04-01

    Modern hydrogen powered polymer electrolyte fuel cells (PEFCs) utilize a micro-porous layer (MPL) consisting of carbon nanoparticles and polytetrafluoroethylene (PTFE) to enhance the transport phenomena and performance while reducing cost. However, the underlying mechanisms are not yet completely understood due to a lack of information about the detailed MPL structure and properties. In the present work, the 3D phase segregated nanostructure of an MPL is revealed for the first time through the development of a customized, non-destructive procedure for monochromatic nano-scale X-ray computed tomography visualization. Utilizing this technique, it is discovered that PTFE is situated in conglomerated regions distributed randomly within connected domains of carbon particles; hence, it is concluded that PTFE acts as a binder for the carbon particles and provides structural support for the MPL. Exposed PTFE surfaces are also observed that will aid the desired hydrophobicity of the material. Additionally, the present approach uniquely enables phase segregated calculation of effective transport properties, as reported herein, which is particularly important for accurate estimation of electrical and thermal conductivity. Overall, the new imaging technique and associated findings may contribute to further performance improvements and cost reduction in support of fuel cell commercialization for clean energy applications.

  11. A novel analytical thermal model for multilevel nano-scale interconnects considering the via effect

    Institute of Scientific and Technical Information of China (English)

    Zhu Zhang-Ming; Li Ru; Hao Bao-Tian; Yang Yin-Tang

    2009-01-01

    Based on the heat diffusion equation of multilevel interconnects, a novel analytical thermal model for multilevel nano-scale interconnects considering the via effect is presented, which can compute quickly the temperature of multilevel interconnects, with substrate temperature given. Based on the proposed model and the 65 nm complementary metal oxide semiconductor (CMOS) process parameter, the temperature of nano-scale interconnects is computed. The computed results show that the via effect has a great effect on local interconnects, but the reduction of thermal conductivity has little effect on local interconnects. With the reduction of thermal conductivity or the increase of current density, however, the temperature of global interconnects rises greatly, which can result in a great deterioration in their performance. The proposed model can be applied to computer aided design (CAD) of very large-scale integrated circuits (VLSIs) in nano-scale technologies.

  12. Shock induced chemical reactions in energetic structural materials

    Science.gov (United States)

    Reding, Derek J.

    Energetic structural materials (ESMs) constitute a new class of materials that provide dual functions of strength and energetic characteristics. ESMs are typically composed of micron-scale or nano-scale intermetallic mixtures or mixtures of metals and metal oxides, polymer binders, and structural reinforcements. Voids are included to produce a composite with favorable chemical reaction characteristics. In this thesis, a continuum approach is used to simulate gas-gun or explosive loading experiments where a strong shock is induced in the ESM by an impacting plate. Algorithms are developed to obtain equations of state of mixtures. It is usually assumed that the shock loading increases the energy of the ESM and causes the ESM to reach the transition state. It is also assumed that the activation energy needed to reach the transition state is a function of the temperature of the mixture. In this thesis, it is proposed that the activation energy is a function of temperature and the stress state of the mixture. The incorporation of such an activation energy is selected in this thesis. Then, a multi-scale chemical reaction model for a heterogeneous mixture is introduced. This model incorporates reaction initiation, propagation, and extent of completed reaction in spatially heterogeneous distributions of reactants. A new model is proposed for the pore collapse of mixtures. This model is formulated by modifying the Carol, Holt, and Nesterenko spherically symmetric model to include mixtures and compressibility effects. Uncertainties in the model result from assumptions in formulating the models for continuum relationships and chemical reactions in mixtures that are distributed heterogeneously in space and in numerical integration of the resulting equations. It is important to quantify these uncertainties. In this thesis, such an uncertainty quantification is investigated by systematically identifying the physical processes that occur during shock compression of ESMs which are

  13. [Study on preparation of composite nano-scale Fe3O4 for phosphorus control].

    Science.gov (United States)

    Li, Lei; Pan, Gang; Chen, Hao

    2010-03-01

    Composite nano-scale Fe3O4 particles were prepared in sodium carboxymethyl cellulose (CMC) solution by the oxidation deposition method. The adsorptions of phosphorus by micro-scale Fe3O4 and composite nano-scale Fe3O4 were investigated in water and soil, and the role of cellulase in the adsorption of composite nano-scale Fe3O4 was studied. Kinetic tests indicated that the equilibrium adsorption capacity of phosphorous on the composite nano-scale Fe3O4 (2.1 mg/g) was less than that of micro-scale Fe3O4 (3.2 mg/g). When cellulase was added to the solution of composite nano-scale Fe3O4 to degrade CMC, the removal rate of P by the nanoparticles (86%) was enhanced to the same level as the microparticles (90%). In the column tests, when the composite nano-scale Fe3O4 suspension was introduced in the downflow mode through the soil column, 72% of Fe3O4 penetrated through the soil bed under gravity. In contrast, the micro-scale Fe3O4 failed to pass through the soil column. The retention rate of P was 45% in the soil column when treated by the CMC-stabilized nanoparticles, in comparison with only 30% for the untreated soil column, however it could be improved to 74% in the soil column when treated by both the CMC-stabilized nanoparticles and cellulase, which degraded CMC after the nanoparticles were delivered into the soil.

  14. LATTICE DEFORMATION AND PHASE TRANSFORMATION FROM NANO-SCALE ANATASE TO NANO-SCALE RUTILE TiO2 PREPARED BY A SOL-GEL TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    Yanqun Shao; Dian Tang; Jinghua Sun; Yekun Lee; Weihao Xiong

    2004-01-01

    Nano-scale rutile phase was transformed from nano-scale anatase upon heating, which was prepared by a sol-gel technique. The XRD data corresponding to the anatase and rutile phases were analyzed and the grain sizes of as-derived phases were calculated by Sherrer equation. The lattice parameters of the as-derived anatase and rutile unit cells were calculated and compared with those of standard lattice parameters on PDF cards. It was shown that the smaller the grain sizes, the larger the lattice deformation. The lattice parameter a has the negative deviation from the standard and the lattice parameter c has the positive deviation for both phases. The particles sizes had preferential influence on the longer parameter between the lattice parameters of a and c. With increasing temperatures, the lattice parameters of a and c in both phases approached to the equilibrium state. The larger lattice deformation facilitated the nucleation process, which lowered the transformation temperature. During the transformation from nano-scale anatase to rutile, besides the mechanism involving retention of the {112} pseudo-close-packed planes of oxygen in anatase as the{100} pseudo-close-packed planes in rutile, the new phase occurred by relaxation of lattice deformation and adjustment of the atomic sites in parent phase. The orientation relationships were suggested to be anatase {101}//rutile {101} and anatase //rutile, and the habit plane was anatase (101),

  15. Nano-scale simulative measuring model for tapping mode atomic force microscopy and analysis for measuring a nano-scale ladder-shape standard sample.

    Science.gov (United States)

    Lin, Zone-Ching; Chou, Ming-Ho

    2010-07-01

    This study proposes to construct a nano-scale simulative measuring model of Tapping Mode Atomic Force Microscopy (TM-AFM), compare with the edge effect of simulative and measurement results. It combines with the Morse potential and vibration theory to calculate the tip-sample atomic interaction force between probe and sample. Used Silicon atoms (Si) arrange the shape of the rectangular cantilever probe and the nano-scale ladder-shape standard sample atomic model. The simulative measurements are compared with the results for the simulative measurements and experimental measurement. It is found that the scan rate and the probe tip's bevel angle are the two reasons to cause the surface error and edge effect of measuring the nano-scale ladder-shape standard sample by TM-AFM. And the bevel angle is about equal to the probe tip's bevel angle from the results of simulated and experimented on the vertical section of the sample edge. To compare with the edge effect between the simulation and experimental measurement, its error is small. It could be verified that the constructed simulative measuring model for TM-AFM in this article is reasonable.

  16. Strength of Materials and Structures

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@ All engineering structures designed according to modern principles have to be strong and sufficiently rigid. Scientists and engineers have long recognized the importance of the strength of materials and structures, and dedicated much their efforts to both fundamental and industrial research into the theory for vast engineering materials and various structures. A lot of engineers need to be familiar with the fundamental principles of strength in materials and structures in order to design structures to resist failures. This book is a very good one to provide them with these principles.

  17. The Influence of Fluorination on Nano-Scale Phase Separation and Photovoltaic Performance of Small Molecular/PC71BM Blends

    Directory of Open Access Journals (Sweden)

    Zhen Lu

    2016-04-01

    Full Text Available To investigate the fluorination influence on the photovoltaic performance of small molecular based organic solar cells (OSCs, six small molecules based on 2,1,3-benzothiadiazole (BT, and diketopyrrolopyrrole (DPP as core and fluorinated phenyl (DFP and triphenyl amine (TPA as different terminal units (DFP-BT-DFP, DFP-BT-TPA, TPA-BT-TPA, DFP-DPP-DFP, DFP-DPP-TPA, and TPA-DPP-TPA were synthesized. With one or two fluorinated phenyl as the end group(s, HOMO level of BT and DPP based small molecular donors were gradually decreased, inducing high open circuit voltage for fluorinated phenyl based OSCs. DFP-BT-TPA and DFP-DPP-TPA based blend films both displayed stronger nano-scale aggregation in comparison to TPA-BT-TPA and TPA-DPP-TPA, respectively, which would also lead to higher hole motilities in devices. Ultimately, improved power conversion efficiency (PCE of 2.17% and 1.22% was acquired for DFP-BT-TPA and DFP-DPP-TPA based devices, respectively. These results demonstrated that the nano-scale aggregation size of small molecules in photovoltaic devices could be significantly enhanced by introducing a fluorine atom at the donor unit of small molecules, which will provide understanding about the relationship of chemical structure and nano-scale phase separation in OSCs.

  18. Nicholas Metropolis Award for Outstanding Doctoral Thesis Work in Computational Physics Talk: Understanding Nano-scale Electronic Systems via Large-scale Computation

    Science.gov (United States)

    Cao, Chao

    2009-03-01

    Nano-scale physical phenomena and processes, especially those in electronics, have drawn great attention in the past decade. Experiments have shown that electronic and transport properties of functionalized carbon nanotubes are sensitive to adsorption of gas molecules such as H2, NO2, and NH3. Similar measurements have also been performed to study adsorption of proteins on other semiconductor nano-wires. These experiments suggest that nano-scale systems can be useful for making future chemical and biological sensors. Aiming to understand the physical mechanisms underlying and governing property changes at nano-scale, we start off by investigating, via first-principles method, the electronic structure of Pd-CNT before and after hydrogen adsorption, and continue with coherent electronic transport using non-equilibrium Green’s function techniques combined with density functional theory. Once our results are fully analyzed they can be used to interpret and understand experimental data, with a few difficult issues to be addressed. Finally, we discuss a newly developed multi-scale computing architecture, OPAL, that coordinates simultaneous execution of multiple codes. Inspired by the capabilities of this computing framework, we present a scenario of future modeling and simulation of multi-scale, multi-physical processes.

  19. 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.

  20. Microstructure Charaterization of a Hardened and Tempered Tool Steel: from Macro to Nano Scale

    DEFF Research Database (Denmark)

    Højerslev, Christian; Somers, Marcel A. J.; Carstensen, Jesper V.

    2002-01-01

    The microstructure of a conventionally heat treated PM AISI M3:2 tool steel, was characterised by a combination of light optical and electron microscopy, covering the range from micro to nano scale. Dilatometry and X-ray diffractometry were used for an overall macro characterisation of the phases...

  1. Biased transportations in a spatially asymmetric system at the nano-scale under thermal noise

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Under the theory of ratchet effect for mesoand macro-scale systems, the additional perturbation with a long time correlation and the breaking of spatial inversion symmetry are two main ingredients to bring unidirected transportations. With the help of a simple model system, we show that a spatially asymmetric system of the nano-scale length may induce biased transportations under thermal noise.

  2. Measurement of the Resonant Frequency of Nano-Scale Cantilevers by Hard Contact Readout

    DEFF Research Database (Denmark)

    Dohn, Søren; Hansen, Ole; Bolsen, A.

    2008-01-01

    It is shown that detection of the resonant frequency of a nano-scale cantilever is possible by measuring the time average current flowing from an electrode to the cantilever during hard contact occurring twice every cycle of the cantilever vibration. The electronic detection method is insensitive....... The readout method is thereby ideally suited for portable sensor systems....

  3. Hypersonic Materials and Structures

    Science.gov (United States)

    Glass, David E.

    2016-01-01

    Thermal protection systems (TPS) and hot structures are required for a range of hypersonic vehicles ranging from ballistic reentry to hypersonic cruise vehicles, both within Earth's atmosphere and non-Earth atmospheres. The focus of this presentation is on air breathing hypersonic vehicles in the Earth's atmosphere. This includes single-stage to orbit (SSTO), two-stage to orbit (TSTO) accelerators, access to space vehicles, and hypersonic cruise vehicles. This paper will start out with a brief discussion of aerodynamic heating and thermal management techniques to address the high heating, followed by an overview of TPS for rocket-launched and air-breathing vehicles. The argument is presented that as we move from rocket-based vehicles to air-breathing vehicles, we need to move away from the insulated airplane approach used on the Space Shuttle Orbiter to a wide range of TPS and hot structure approaches. The primary portion of the paper will discuss issues and design options for CMC TPS and hot structure components, including leading edges, acreage TPS, and control surfaces. The current state-of-the-art will be briefly discussed for some of the components.

  4. Study on Cutting Performance of Nano-scale Zirconia Toughening Alumina Matrix Ceramic Tool Materials (Ⅱ)%纳米氧化锆增韧氧化铝基陶瓷刀具切削性能的研究(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    钟金豹

    2014-01-01

    研究新型陶瓷刀具A15Zc和A20Z(c+m)切削淬硬40Cr合金钢时的切削性能,并与已经商业化的陶瓷刀具SG4的切削性能进行了对比。结果表明:刀具后刀面磨损量随切削深度的增加而增大,而切削速度对刀具后刀面磨损量的影响较小;在较小的切削深度下切削时刀具具有良好的切削性能,A15Zc和A20Z(c+m)的抗磨损能力都好于SG4刀具;刀具的主要磨损形态为前后刀面磨损,主要磨损机制为前刀面的黏结磨损和后刀面的磨粒磨损。%Compared to the commercial ceramic tool SG4,the performances of nano-scale ZrO2 toughening Al2O3 matrix ceram-ics tool in machining the hardened 40Cr alloy steel,such as A15Zc and A20Z(c+m),were studied. When the hardened 40Cr alloy steel is machined,the tool flank wear widthes of A15Zc and A20Z(c+m)are increased with an increase of the cut depth and the effect of cutting speed on cutting performance is small. A15Zc and A20Z(c+m)have stronger wear resistance than SG4 at the smaller cut depth. The main wear patterns are tool wear on the rake face and flank,and the main wear mechanisms are bonding wear on tool rake face and abrasive wear on tool flank.

  5. Porous Materials - Structure and Properties

    DEFF Research Database (Denmark)

    Nielsen, Anders

    1997-01-01

    The paper presents some viewpoints on the description of the pore structure and the modelling of the properties of the porous building materials. Two examples are given , where it has been possible to connect the pore structure to the properties: Shrinkage of autoclaved aerated concrete and the p......The paper presents some viewpoints on the description of the pore structure and the modelling of the properties of the porous building materials. Two examples are given , where it has been possible to connect the pore structure to the properties: Shrinkage of autoclaved aerated concrete...

  6. Optimal lattice-structured materials

    Science.gov (United States)

    Messner, Mark C.

    2016-11-01

    This work describes a method for optimizing the mesostructure of lattice-structured materials. These materials are periodic arrays of slender members resembling efficient, lightweight macroscale structures like bridges and frame buildings. Current additive manufacturing technologies can assemble lattice structures with length scales ranging from nanometers to millimeters. Previous work demonstrates that lattice materials have excellent stiffness- and strength-to-weight scaling, outperforming natural materials. However, there are currently no methods for producing optimal mesostructures that consider the full space of possible 3D lattice topologies. The inverse homogenization approach for optimizing the periodic structure of lattice materials requires a parameterized, homogenized material model describing the response of an arbitrary structure. This work develops such a model, starting with a method for describing the long-wavelength, macroscale deformation of an arbitrary lattice. The work combines the homogenized model with a parameterized description of the total design space to generate a parameterized model. Finally, the work describes an optimization method capable of producing optimal mesostructures. Several examples demonstrate the optimization method. One of these examples produces an elastically isotropic, maximally stiff structure, here called the isotruss, that arguably outperforms the anisotropic octet truss topology.

  7. Direct electrochemistry and electrocatalytic activity of catalase immobilized onto electrodeposited nano-scale islands of nickel oxide.

    Science.gov (United States)

    Salimi, Abdollah; Sharifi, Ensiyeh; Noorbakhsh, Abdollah; Soltanian, Saied

    2007-02-01

    Cyclic voltammetry was used for simultaneous formation and immobilization of nickel oxide nano-scale islands and catalase on glassy carbon electrode. Electrodeposited nickel oxide may be a promising material for enzyme immobilization owing to its high biocompatibility and large surface. The catalase films assembled on nickel oxide exhibited a pair of well defined, stable and nearly reversible CV peaks at about -0.05 V vs. SCE at pH 7, characteristic of the heme Fe (III)/Fe (II) redox couple. The formal potential of catalase in nickel oxide film were linearly varied in the range 1-12 with slope of 58.426 mV/pH, indicating that the electron transfer is accompanied by single proton transportation. The electron transfer between catalase and electrode surface, (k(s)) of 3.7(+/-0.1) s(-1) was greatly facilitated in the microenvironment of nickel oxide film. The electrocatalytic reduction of hydrogen peroxide at glassy carbon electrode modified with nickel oxide nano-scale islands and catalase enzyme has been studied. The embedded catalase in NiO nanoparticles showed excellent electrocatalytic activity toward hydrogen peroxide reduction. Also the modified rotating disk electrode shows good analytical performance for amperometric determination of hydrogen peroxide. The resultant catalase/nickel oxide modified glassy carbon electrodes exhibited fast amperometric response (within 2 s) to hydrogen peroxide reduction (with a linear range from 1 microM to 1 mM), excellent stability, long term life and good reproducibility. The apparent Michaelis-Menten constant is calculated to be 0.96(+/-0.05)mM, which shows a large catalytic activity of catalase in the nickel oxide film toward hydrogen peroxide. The excellent electrochemical reversibility of redox couple, high stability, technical simplicity, lake of need for mediators and short preparations times are advantages of this electrode. Finally the activity of biosensor for nitrite reduction was also investigated.

  8. Multi-objective optimization and exergetic-sustainability of an irreversible nano scale Braysson cycle operating with Ma

    Directory of Open Access Journals (Sweden)

    Mohammad H. Ahmadi

    2016-06-01

    Full Text Available Nano technology is developed in this decade and changes the way of life. Moreover, developing nano technology has effect on the performance of the materials and consequently improves the efficiency and robustness of them. So, nano scale thermal cycles will be probably engaged in the near future. In this paper, a nano scale irreversible Braysson cycle is studied thermodynamically for optimizing the performance of the Braysson cycle. In the aforementioned cycle an ideal Maxwell–Boltzmann gas is used as a working fluid. Furthermore, three different plans are used for optimizing with multi-objectives; though, the outputs of the abovementioned plans are assessed autonomously. Throughout the first plan, with the purpose of maximizing the ecological coefficient of performance and energy efficiency of the system, multi-objective optimization algorithms are used. Furthermore, in the second plan, two objective functions containing the ecological coefficient of performance and the dimensionless Maximum available work are maximized synchronously by utilizing multi-objective optimization approach. Finally, throughout the third plan, three objective functions involving the dimensionless Maximum available work, the ecological coefficient of performance and energy efficiency of the system are maximized synchronously by utilizing multi-objective optimization approach. The multi-objective evolutionary approach based on the non-dominated sorting genetic algorithm approach is used in this research. Making a decision is performed by three different decision makers comprising linear programming approaches for multidimensional analysis of preference and an approach for order of preference by comparison with ideal answer and Bellman–Zadeh. Lastly, analysis of error is employed to determine deviation of the outcomes gained from each plan.

  9. Nano-scale experimental investigation of in-situ wettability and spontaneous imbibition in ultra-tight reservoir rocks

    Science.gov (United States)

    Akbarabadi, Morteza; Saraji, Soheil; Piri, Mohammad; Georgi, Dan; Delshad, Mohammad

    2017-09-01

    We investigated spontaneous imbibition behavior, three-dimensional fluid occupancy maps, and in-situ wettability at the nano scale in five ultra-tight and shale reservoir rock samples. For this purpose, we developed a novel technique by integrating a custom-built in-situ miniature fluid-injection module with a non-destructive high-resolution X-ray imaging system. Small cylindrical core samples (15-60 μm in diameter) were prepared from reservoir rocks using Focused-Ion Beam (FIB) milling technique. The pore network inside the samples were first characterized using ultra-high resolution three-dimensional images obtained at initial state by X-ray nano-tomography (Nano-CT) and FIB-Scanning Electron Microscopy (FIB-SEM) techniques at the nano scale. The petrophysical parameters, including porosity, permeability, pore-size distribution, and organic content were computed for each sample using image analysis. We then performed series of imbibition experiments using brine, oil, and surfactant solutions on each core sample. We observed that both oil and brine phases spontaneously imbibe into the pore network of the rock samples at various quantities. We also, for the first time, examined fluid distribution in individual pores and found a complex wettability behavior at the pore scale in the reservoir rock samples. Three pore types were identified with water-wet, oil-wet, and fractionally-wet behaviors. This work opens a new path to developing an improved understanding of the pore-level physics involved in multi-phase flow and transport not only in tight rock samples but also in other nanoporous material used in different science and engineering applications.

  10. Carbopol 934, 940 and Ultrez 10 as viscosity modifiers of palm olein esters based nano-scaled emulsion containing ibuprofen.

    Science.gov (United States)

    Abdullah, Ghassan Zuhair; Abdulkarim, Muthanna Fawzy; Mallikarjun, Chitneni; Mahdi, Elrashid Saleh; Basri, Mahiran; Sattar, Munavvar Abdul; Noor, Azmin Mohd

    2013-01-01

    Micro-emulsions and sometimes nano-emulsions are well known candidates to deliver drugs locally. However, the poor rheological properties are marginally affecting their acceptance pharmaceutically. This work aimed to modify the poor flow properties of a nano-scaled emulsion comprising palm olein esters as the oil phase and ibuprofen as the active ingredient for topical delivery. Three Carbopol ® resins: 934, 940 and Ultrez 10, were utilized in various concentrations to achieve these goals. Moreover, phosphate buffer and triethanolamine solutions pH 7.4 were used as neutralizing agents to assess their effects on the gel-forming and swelling properties of Carbopol ® 940. The addition of these polymers caused the produced nano-scaled emulsion to show a dramatic droplets enlargement of the dispersed globules, increased intrinsic viscosity, consistent zeta potential and transparent-to-opaque change in appearance. These changes were relatively influenced by the type and the concentration of the resin used. Carbopol ® 940 and triethanolamine appeared to be superior in achieving the proposed tasks compared to other materials. The higher the pH of triethanolamine solution, the stronger the flow-modifying properties of Carbopol ® 940. Transmission electron microscopy confirmed the formation of a well-arranged gel network of Carbopol ® 940, which was the major cause for all realized changes. Later in vitro permeation studies showed a significant decrease in the drug penetration, thus further modification using 10% w/w menthol or limonene as permeation promoters was performed. This resulted in in vitro and in vivo pharmacodynamics properties that are comparably higher than the reference chosen for this study.

  11. Polarization Engineering in Nano-Scale Waveguides Using Lossless Media

    CERN Document Server

    Chang, PoHan; Helmy, Amr S

    2016-01-01

    A device that achieves controllable rotation of the state of polarization by rotating the orientation of the eigenmodes of a waveguide by 45$^{\\circ}$ is introduced and analyzed. The device can be implemented using lossless materials on a nanoscale and helps circumvent the inherent polarization dependence of photonic devices realized within the silicon on insulator platform. We propose and evaluate two novel polarization rotator-based schemes to achieve polarization engineering functions: (1) A multi-purpose device, with dimensions on the order of a few wavelengths which can function as a polarization splitter or an arbitrary linear polarization state generator. (2) An energy efficient optical modulator that utilizes eigenmode rotation and epsilon near zero (ENZ) effects to achieve high extinction ratio, polarization insensitive amplitude modulation without the need to sweep the device geometry to match the TE and TM mode attributes. By using indium tin oxide (ITO) as an example for a tunable material, the pr...

  12. Structural Chemistry of Functional Materials

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ This innovative research group on structural chemistry of functional materials was approved by NSFC in 2005.Headed by Prof.HONG Maochun, the team consists of several young research scientists from the CAS Fujian Institute of Research on the Structures of Matter, including Profs CAO Rong, LU Canzhong, GUO Guocong, CHEN Zhongning, MAO Jianggao Mao and CHEN Ling.

  13. The surface parameters modifications at nano scale for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Safonov, V; Zykova, A; Smolik, J; Rogovska, R; Donkov, N; Georgieva, V, E-mail: zykov@bi.com.u

    2010-11-01

    Functional coatings deposition is an effective way of surface modification with direct control of stoichiometry, impurity elements, functional groups and surface charges. Modified surface properties such as composition, roughness, wettability have effect on the most important processes at biomaterial interface. The aim of present study was the analysis of surface roughness and surface free energy parameters of oxide Al{sub 2}O{sub 3} and Ta{sub 2}O{sub 5} coatings and the possibility to separate the influence of such factors on the regularities and mechanisms of nano materials interactions with the biological objects.

  14. Nano-scale orientation mapping of graphite in cast irons

    Energy Technology Data Exchange (ETDEWEB)

    Theuwissen, Koenraad; Lacaze, Jacques [Institut CARNOT CIRIMAT, Université de Toulouse, ENSIACET, CS 44362, 31030 Toulouse Cedex 4 (France); Véron, Muriel [SIMAP, CNRS-Grenoble INP, BP 46 101 rue de la Physique, 38402 Saint Martin d' Hères (France); Laffont, Lydia, E-mail: lydia.laffont@ensiacet.fr [Institut CARNOT CIRIMAT, Université de Toulouse, ENSIACET, CS 44362, 31030 Toulouse Cedex 4 (France)

    2014-09-15

    A diametrical section of a graphite spheroid from a ductile iron sample was prepared using the focused ion beam-lift out technique. Characterization of this section was carried out through automated crystal orientation mapping in a transmission electron microscope. This new technique automatically collects electron diffraction patterns and matches them with precalculated templates. The results of this investigation are crystal orientation and phase maps of the specimen, which bring new light to the understanding of growth mechanisms of this peculiar graphite morphology. This article shows that mapping the orientation of carbon-based materials such as graphite, which is difficult to achieve with conventional techniques, can be performed automatically and at high spatial resolution using automated crystal orientation mapping in a transmission electron microscope. - Highlights: • ACOM/TEM can be used to study the crystal orientation of carbon-based materials. • A spheroid is formed by conical sectors radiating from a central nuclei. • Misorientations exist within the conical sectors, defining various orientation domains.

  15. Shake-Rattle-and-Roll: A Model of Dynamic Structural Disorder in Supported Nanoscale Catalysts

    CERN Document Server

    Rehr, J J

    2013-01-01

    We investigate the effects of "dynamic structural disorder" (DSD) on the behavior of 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 energy, charge, and other extensive quantities as well as large surface effects. The DSD is driven 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 DSD is based on a combination of statistical mechanics, transient coupled-oscillator models, and real-time DFT/MD simulations. This approach treats thermal and dynamic effects over multiple time-scales, including bond-stretching and -bending vibrations, DSD, and transient tethering to the substrate at longer ps time-scales. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the ...

  16. Nano-Scale Devices for Frequency-Based Magnetic Biosensing

    Science.gov (United States)

    2017-01-31

    electrically contact a spin torque oscillator on a small rectangular silicon wafer which is mounted above one of the (silver) poles of a projected field...versus those induced by large particles which sit on top of the nanopatterened structure (Sec. IIIC in [3]). 1b. Using magnonic crystals for particle...or perhaps a slightly angled device wafer. DISTRIBUTION A. Approved for public release: distribution unlimited. Fig. 4. (a) Top -down SEM

  17. 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.

  18. Quantum Boltzmann equation solved by Monte Carlo method for nano-scale semiconductor devices simulation

    Institute of Scientific and Technical Information of China (English)

    Du Gang; Liu Xiao-Yan; Han Ru-Qi

    2006-01-01

    A two-dimensional (2D) full band self-consistent ensemble Monte Carlo (MC) method for solving the quantum Boltzmann equation, including collision broadening and quantum potential corrections, is developed to extend the MC method to the study of nano-scale semiconductor devices with obvious quantum mechanical (QM) effects. The quantum effects both in real space and momentum space in nano-scale semiconductor devices can be simulated. The effective mobility in the inversion layer of n and p channel MOSFET is simulated and compared with experimental data to verify this method. With this method 50nm ultra thin body silicon on insulator MOSFET are simulated. Results indicate that this method can be used to simulate the 2D QM effects in semiconductor devices including tunnelling effect.

  19. Investigation on the special Smith-Purcell radiation from a nano-scale rectangular metallic grating

    Science.gov (United States)

    Li, Weiwei; Liu, Weihao; Jia, Qika

    2016-03-01

    The special Smith-Purcell radiation (S-SPR), which is from the radiating eigen modes of a grating, has remarkable higher intensity than the ordinary Smith-Purcell radiation. Yet in previous studies, the gratings were treated as perfect conductor without considering the surface plasmon polaritons (SPPs) which are of significance for the nano-scale gratings especially in the optical region. In present paper, the rigorous theoretical investigations on the S-SPR from a nano-grating with SPPs taken into consideration are carried out. The dispersion relations and radiation characteristics are obtained, and the results are verified by simulations. According to the analyses, the tunable light radiation can be achieved by the S-SPR from a nano-grating, which offers a new prospect for developing the nano-scale light sources.

  20. Nano-Scale Interpenetrating Phase Composites (IPC S) for Industrial and Vehicle Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hemrick, James Gordon [ORNL; Hu, Michael Z. [ORNL

    2010-06-01

    A one-year project was completed at Oak Ridge National Laboratory (ORNL) to explore the technical and economic feasibility of producing nano-scale Interpenetrating Phase Composite (IPC) components of a usable size for actual testing/implementation in a real applications such as high wear/corrosion resistant refractory shapes for industrial applications, lightweight vehicle braking system components, or lower cost/higher performance military body and vehicle armor. Nano-scale IPC s with improved mechanical, electrical, and thermal properties have previously been demonstrated at the lab scale, but have been limited in size. The work performed under this project was focused on investigating the ability to take the current traditional lab scale processes to a manufacturing scale through scaling of these processes or through the utilization of an alternative high-temperature process.

  1. Stabilizing the body centered cubic crystal in titanium alloys by a nano-scale concentration modulation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H. L.; Shah, S. A. A.; Hao, Y. L.; Prima, F.; Li, T.; Cairney, J. M.; Wang, Y. D.; Wang, Y.; Obbard, E. G.; Li, S. J.; Yang, R.

    2017-04-01

    It is well-known that the body centered cubic (bcc) crystal in titanium alloys reaches its stability limit as the electron-to-atom (e/a) ratio of the alloy drops down to ~4.24. This critical value, however, is much higher than that of a multifunctional bcc type alloy (e/a = 4.15). Here we demonstrate that a nano-scale concentration modulation created by spinodal decomposition is what stabilizes the bcc crystal of the alloy. Aided by such a nano-scale concentration heterogeneity, unexpected properties from its chemically homogeneous counterpart are obtained. This provides a new strategy to design functional titanium alloys by tuning the spinodal decomposition.

  2. Emulsified Zero-Valent Nano-Scale Iron Treatment of Chlorinated Solvent DNAPL Source Areas

    Science.gov (United States)

    2010-09-01

    value nZVI nano -scale ZVI O&M operation and maintenance ORP oxidation-reduction potential P&T pump -and-treat PCE tetrachloroethene PRB...grade surfactant, biodegradable oil, water, and ZVI particles (either nano - or micro -scale iron, nZVI, or mZVI), which form emulsion particles. The...is composed of food- grade surfactant, biodegradable oil, water, and ZVI particles (either nano - or micro -scale iron, nZVI, or mZVI), which form

  3. Novel Nano-scale Overlay Alignment Method for Room-temperature Imprint Lithography

    Institute of Scientific and Technical Information of China (English)

    WANG Li; DING Yu-cheng; LU Bing-heng; LI Han-song; YAN Le; QIU Zhi-hui; LIU Hong-zhong; YIN Lie

    2005-01-01

    A novel nano-scale alignment technique based on Moiré signal for room-temperature imprint are used to estimate the alignment errors in x and y directions. The experiment result indicates that complex and the alignment resolutions obtained in x and y directions are ±20 nm(3σ) and ±24 nm(3σ). They can meet the requirement of alignment accuracy for submicron imprint lithography.

  4. Characterization of nano-scale protective oxide films: application on metal chemical mechanical planarization

    OpenAIRE

    Karagöz, Ayşe; Craciun, V.; Başım, Gül Bahar

    2015-01-01

    This study focuses on the characterization of nano-scale metal oxide films for chemical mechanical planarization (CMP) applications. The protective nature of the self-grown metal oxide layers in the CMP slurry environment enable topographic selectivity required for metallization of interconnects. Tungsten was selected as the model metal film to study the formation and characteristics of the metal oxide nano-layers since tungsten CMP is very well-established in conventional semiconductor manuf...

  5. Design exploration of emerging nano-scale non-volatile memory

    CERN Document Server

    Yu, Hao

    2014-01-01

    This book presents the latest techniques for characterization, modeling and design for nano-scale non-volatile memory (NVM) devices.  Coverage focuses on fundamental NVM device fabrication and characterization, internal state identification of memristic dynamics with physics modeling, NVM circuit design, and hybrid NVM memory system design-space optimization. The authors discuss design methodologies for nano-scale NVM devices from a circuits/systems perspective, including the general foundations for the fundamental memristic dynamics in NVM devices.  Coverage includes physical modeling, as well as the development of a platform to explore novel hybrid CMOS and NVM circuit and system design.   • Offers readers a systematic and comprehensive treatment of emerging nano-scale non-volatile memory (NVM) devices; • Focuses on the internal state of NVM memristic dynamics, novel NVM readout and memory cell circuit design, and hybrid NVM memory system optimization; • Provides both theoretical analysis and pr...

  6. Nano-scaled iron-carbon precipitates in HSLC and HSLA steels

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper studies the composition, quantity and particle size distribution of nano-scaled precipitates with size less than 20 nm in high strength low carbon (HSLC) steel and their effects on mechanical properties of HSLC steel by means of mass balance calculation of nano-scaled precipitates measured by chemical phase analysis plus SAXS method, high-resolution TEM analysis and thermodynamics calculation, as well as temper rapid cooling treatment of ZJ330. It is found that there existed a large quantity of nano-scaled iron-carbon precipitates with size less than 18 nm in low carbon steel produced by CSP and they are mainly Fe-O-C and Fe-Ti-O-C precipitates formed below temperature A1. These precipitates have ob- vious precipitation strengthening effect on HSLC steel and this may be regarded as one of the main reasons why HSLC steel has higher strength. There also existed a lot of iron-carbon precipitates with size less than 36 nm in HSLA steels.

  7. Nano-scaled iron-carbon precipitates in HSLC and HSLA steels

    Institute of Scientific and Technical Information of China (English)

    FU Jie; WU HuaJie; LIU YangChun; KANG YongLin

    2007-01-01

    This paper studies the composition, quantity and particle size distribution of nano-scaled precipitates with size less than 20 nm in high strength Iow carbon (HSLC) steel and their effects on mechanical properties of HSLC steel by means of mass balance calculation of nano-scaled precipitates measured by chemical phase analysis plus SAXS method, high-resolution TEM analysis and thermodynamics calculation, as well as temper rapid cooling treatment of ZJ330. It is found that there existed a large quantity of nano-scaled iron-carbon precipitates with size less than 18 nm in Iow carbon steel produced by CSP and they are mainly Fe-O-C and Fe-Ti-O-C precipitates formed below temperature A1. These precipitates have obvious precipitation strengthening effect on HSLC steel and this may be regarded as one of the main reasons why HSLC steel has higher strength. There also existed a lot of iron-carbon precipitates with size less than 36 nm in HSLA steels.

  8. Carbopol 934, 940 and Ultrez 10 as viscosity modifiers of palm olein esters based nano-scaled emulsion containing ibuprofen

    National Research Council Canada - National Science Library

    Abdullah, Ghassan Zuhair; Abdulkarim, Muthanna Fawzy; Mallikarjun, Chitneni; Mahdi, Elrashid Saleh; Basri, Mahiran; Sattar, Munavvar Abdul; Noor, Azmin Mohd

    2013-01-01

    .... This work aimed to modify the poor flow properties of a nano-scaled emulsion comprising palm olein esters as the oil phase and ibuprofen as the active ingredient for topical delivery. Three Carbopol ® resins...

  9. Anodized 3D-printed titanium implants with dual micro- and nano-scale topography promote interaction with human osteoblasts and osteocyte-like cells.

    Science.gov (United States)

    Gulati, Karan; Prideaux, Matthew; Kogawa, Masakazu; Lima-Marques, Luis; Atkins, Gerald J; Findlay, David M; Losic, Dusan

    2016-12-07

    The success of implantation of materials into bone is governed by effective osseointegration, requiring biocompatibility of the material and the attachment and differentiation of osteoblastic cells. To enhance cellular function in response to the implant surface, micro- and nano-scale topography have been suggested as essential. In this study, we present bone implants based on 3D-printed titanium alloy (Ti6Al4V), with a unique dual topography composed of micron-sized spherical particles and vertically aligned titania nanotubes. The implants were prepared by combination of 3D-printing and anodization processes, which are scalable, simple and cost-effective. The osseointegration properties of fabricated implants, examined using human osteoblasts, showed enhanced adhesion of osteoblasts compared with titanium materials commonly used as orthopaedic implants. Gene expression studies at early (day 7) and late (day 21) stages of culture were consistent with the Ti substrates inducing an osteoblast phenotype conducive to effective osseointegration. These implants with the unique combination of micro- and nano-scale topography are proposed as the new generation of multi-functional bone implants, suitable for addressing many orthopaedic challenges, including implant rejection, poor osseointegration, inflammation, drug delivery and bone healing. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Radiation damage of structural materials

    CERN Document Server

    Koutsky, Jaroslav

    1994-01-01

    Maintaining the integrity of nuclear power plants is critical in the prevention or control of severe accidents. This monograph deals with both basic groups of structural materials used in the design of light-water nuclear reactors, making the primary safety barriers of NPPs. Emphasis is placed on materials used in VVER-type nuclear reactors: Cr-Mo-V and Cr-Ni-Mo-V steel for RPV and Zr-Nb alloys for fuel element cladding. The book is divided into 7 main chapters, with the exception of the opening one and the chapter providing a phenomenological background for the subject of radiation damage. Ch

  11. Fast multi-particle scattering: a hybrid solver for the Maxwell equations in microstructured materials

    CERN Document Server

    Gimbutas, Zydrunas

    2011-01-01

    A variety of problems in device and materials design require the rapid forward modeling of Maxwell's equations in complex micro-structured materials. By combining high-order accurate integral equation methods with classical multiple scattering theory, we have created an effective simulation tool for materials consisting of an isotropic background in which are dispersed a large number of micro- or nano-scale metallic or dielectric inclusions.

  12. Atomic and nano-scale characterization of a 50-year-old hydrated C3S paste

    KAUST Repository

    Geng, Guoqing

    2015-07-15

    This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C-S-H fibers are composed of particles that are 1.5-2 nm thick and several tens of nanometers long. 29Si NMR shows 47.9% Q1 and 52.1% Q2, with a mean SiO4 tetrahedron chain length (MCL) of 4.18, indicating a limited degree of polymerization after 50 years\\' hydration. A Scanning Transmission X-ray Microscopy (STXM) study was conducted on this late-age paste and a 1.5 year old hydrated C3S solution. Near Edge X-ray Absorption Fine Structure (NEXAFS) at Ca L3,2-edge indicates that Ca2 + in C-S-H is in an irregular symmetric coordination, which agrees more with the atomic structure of tobermorite than that of jennite. At Si K-edge, multi-scattering phenomenon is sensitive to the degree of polymerization, which has the potential to unveil the structure of the SiO44 - tetrahedron chain. © 2015 Elsevier Ltd. All rights reserved.

  13. Two-step preparation of nano-scaled magnetic chitosan particles using Triton X-100 reversed-phase water-in-oil microemulsion system

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhengkun; Jiang, Feihong [College of Food Science and Engineering, Northwest A and F University, Yangling, Shaanxi 712100 (China); Lee, Tung-Ching, E-mail: lee@aesop.rutgers.edu [Department of Food Science, Rutgers, the State University of New Jersey, 65 Dudley Road, New Brunswick, NJ 08901 (United States); Yue, Tianli, E-mail: yuetl305@nwsuaf.edu.cn [College of Food Science and Engineering, Northwest A and F University, Yangling, Shaanxi 712100 (China)

    2013-12-25

    Highlights: •A new two-step route for nano-scaled magnetic chitosan particles preparation. •Triton X-100 reversed-phase microemulsion system was used for chitosan coating. •Narrow size distribution of magnetic chitosan nanoparticles was achieved. •Quantitative evaluation of recoverability for the magnetic chitosan nanoparticles. -- Abstract: A new two-step route for the preparation of nano-scaled magnetic chitosan particles has been developed, different from reported one-step in situ preparation and two-step preparation method of reversed-phase suspension, Triton X-100 reversed-phase water-in-oil microemulsion encapsulation method was employed in coating the pre-prepared Fe{sub 3}O{sub 4} nanoparticles with chitosan. The resultant magnetic chitosan particles owned a narrow size distribution ranging from 50 to 92 nm. X-ray diffraction patterns (XRD) indicated that the chitosan coating procedure did not change the spinal structure of Fe{sub 3}O{sub 4} magnetic nanoparticles. The results of Fourier transform infrared (FTIR) analysis and thermogravimetric analysis (TGA) demonstrated that the chitosan was coated on Fe{sub 3}O{sub 4} nanoparticles and its average mass content was ∼50%. The saturated magnetization of the magnetic Fe{sub 3}O{sub 4}/chitosan nanoparticles reached 18.62 emu/g, meanwhile, the nanoparticles showed the characteristics of superparamagnetism. The magnetic chitosan nanoparticles showed a high recoverability of 99.99% in 10 min when pH exceeded 4. The results suggested that the as-prepared magnetic chitosan particles were nano-scaled with a narrow size distribution and a high recoverability.

  14. High voltage stability of LiCoO2 particles with a nano-scale Lipon coating

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yoongu [ORNL; Veith, Gabriel M [ORNL; Nanda, Jagjit [ORNL; Unocic, Raymond R [ORNL; Dudney, Nancy J [ORNL

    2011-01-01

    For high-voltage cycling of rechargeable Li batteries, a nano-scale amorphous Li-ion conductor, lithium phosphorus oxynitride (Lipon), has been coated on surfaces of LiCoO{sub 2} particles by combining a RF-magnetron sputtering technique and mechanical agitation of LiCoO{sub 2} powders. LiCoO{sub 2} particles coated with 0.36 wt% ({approx}1 nm thick) of the amorphous Lipon, retain 90% of their original capacity compared to non-coated cathode materials that retain only 65% of their original capacity after more than 40 cycles in the 3.0-4.4 V range with a standard carbonate electrolyte. The reason for the better high-voltage cycling behavior is attributed to reduction in the side reactions that cause increase of the cell resistance during cycling. Further, Lipon coated particles are not damaged, whereas uncoated particles are badly cracked after cycling. Extending the charge of Lipon-coated LiCoO{sub 2} to higher voltage enhances the specific capacity, but more importantly the Lipon-coated material is also more stable and tolerant of high voltage excursions. A drawback of Lipon coating, particularly as thicker films are applied to cathode powders, is the increased electronic resistance that reduces the power performance.

  15. Characterization of Nano-scale Aluminum Oxide Transport Through Porous Media

    Science.gov (United States)

    Norwood, Sasha Norien

    Land application of biosolids has become common practice in the United States as an alternative to industrial fertilizers. Although nutrient rich, biosolids have been found to contain high concentrations of unregulated and/or unrecognized emerging contaminants (e.g., pharmaceuticals, personal care products) while containing a significant fraction of inorganic nano-scale colloidal materials such as oxides of iron, titanium, and aluminum. Given their reactivity and small size, there are many questions concerning the potential migration of these nano-sized colloidal materials through the soil column and into our surface and groundwater bodies. Transport of emerging pollutants of concern through the soil column, at minimum, is impacted by colloidal properties (e.g., chemical composition, shape, aggregation kinetics), solution chemistry (e.g., pH, ionic strength, natural organic matter), and water flow velocity. The purpose of this current research was to characterize the long-term transport behavior of aluminum oxide nanoparticles (Al 2O3) through a natural porous media with changes in pH, aqueous-phase concentration, pore-water velocity and electrolyte valence. Additionally, deposition rates during the initial stages of deposition were compared to several models developed based on colloid filtration theory and DLVO stability theory. Benchtop column laboratory experiments showed that, under environmentally relevant groundwater conditions, Al2O3 nanoparticles are mobile through saturated porous media. Mobility increased under conditions in which the nanoparticles and porous media were of like charge (pH 9). Changes in linear pore water velocity, under these same high pH conditions, showed similar transport behavior with little mass retained in the system. Deposition is believed to be kinetically controlled at pH 9, as evidenced by the slightly earlier breakthrough as flow rate increased and was further supported by observed concentration effects on the arrival wave

  16. 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.

  17. Nano scale modal confinement in 3D gap plasmon polariton cavities

    CERN Document Server

    Feigenbaum, E; Feigenbaum, Eyal; Orenstein, Meir

    2006-01-01

    Modal volumes at the nano-scale, much smaller than the "diffraction limit", with moderate quality factors, are demonstrated for a dielectric cylinder embedded in between metal plates. The modal field is bounded between the metal interfaces and can be reduced in size almost indefinitely in this dimension. But more controversial - due to the "plasmonic" effect - this reduction is accompanied by a similar in-plane modal size reduction. Another intriguing result is that higher order cavity modes exhibit lower radiation loss. The scheme is studied with effective index analysis, validated by FDTD simulations.

  18. Design and synthesis of new polyaromatic scaffolds for nano-scale applications

    OpenAIRE

    de Mendoza Bonmatí, Paula

    2010-01-01

    Design and Synthesis of New Polyaromatic Scaffolds for Nano-Scale ApplicationsResumen: En la última década, el diseño y la síntesis de nuevos sistemas poliaromáticos han resultado de gran interés gracias a sus propiedades únicas y sus aplicaciones potenciales para la obtención de dispositivos electrónicos, y como precursores de fullerenos. Hemos estudiado el mecanismo que procede a través de la activación del enlace C-H en la reacción intramolecular de arilación directa catalizada por paladio...

  19. Detecting Nano-Scale Vibrations in Rotating Devices by Using Advanced Computational Methods

    Directory of Open Access Journals (Sweden)

    Raúl M. del Toro

    2010-05-01

    Full Text Available This paper presents a computational method for detecting vibrations related to eccentricity in ultra precision rotation devices used for nano-scale manufacturing. The vibration is indirectly measured via a frequency domain analysis of the signal from a piezoelectric sensor attached to the stationary component of the rotating device. The algorithm searches for particular harmonic sequences associated with the eccentricity of the device rotation axis. The detected sequence is quantified and serves as input to a regression model that estimates the eccentricity. A case study presents the application of the computational algorithm during precision manufacturing processes.

  20. 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.

  1. Developing an Effective Model for Shale Gas Flow in Nano-scale Pore Clusters based on FIB-SEM Images

    Science.gov (United States)

    Jiang, W. B.; Lin, M.; Yi, Z. X.; Li, H. S.

    2016-12-01

    Nano-scale pores existed in the form of clusters are the controlling void space in shale gas reservoir. Gas transport in nanopores which has a significant influence on shale gas' recoverability displays multiple transport regimes, including viscous, slippage flow and Knudsen diffusion. In addition, it is also influenced by pore space characteristics. For convenience and efficiency consideration, it is necessary to develop an upscaling model from nano pore to pore cluster scale. Existing models are more like framework functions that provide a format, because the parameters that represent pore space characteristics are underdetermined and may have multiple possibilities. Therefore, it is urgent to make them clear and obtained a model that is closer to reality. FIB-SEM imaging technology is able to acquire three dimensional images with nanometer resolution that nano pores can be visible. Based on the images of two shale samples, we used a high-precision pore network extraction algorithm to generate equivalent pore networks and simulate multiple regime (non-Darcy) flow in it. Several structural parameters can be obtained through pore network modelling. It is found that although the throat-radius distributions are very close, throat flux-radius distributions of different samples can be divided into two categories. The variation of tortuosity with pressure and the overall trend of throat-flux distribution changes with pressure are disclosed. A deeper understanding of shale gas flow in nano-scale pore clusters is obtained. After all, an upscaling model that connects absolute permeability, apparent permeability and other characteristic parameters is proposed, and the best parameter scheme considering throat number-radius distribution and flowing porosity for this model is selected out of three schemes based on pore scale results, and it can avoid multiple-solution problem and is useful in reservoir modelling and experiment result analysis, etc. This work is supported by

  2. Temperature variations at nano-scale level in phase transformed nanocrystalline NiTi shape memory alloys adjacent to graphene layers.

    Science.gov (United States)

    Amini, Abbas; Cheng, Chun; Naebe, Minoo; Church, Jeffrey S; Hameed, Nishar; Asgari, Alireza; Will, Frank

    2013-07-21

    The detection and control of the temperature variation at the nano-scale level of thermo-mechanical materials during a compression process have been challenging issues. In this paper, an empirical method is proposed to predict the temperature at the nano-scale level during the solid-state phase transition phenomenon in NiTi shape memory alloys. Isothermal data was used as a reference to determine the temperature change at different loading rates. The temperature of the phase transformed zone underneath the tip increased by ∼3 to 40 °C as the loading rate increased. The temperature approached a constant with further increase in indentation depth. A few layers of graphene were used to enhance the cooling process at different loading rates. Due to the presence of graphene layers the temperature beneath the tip decreased by a further ∼3 to 10 °C depending on the loading rate. Compared with highly polished NiTi, deeper indentation depths were also observed during the solid-state phase transition, especially at the rate dependent zones. Larger superelastic deformations confirmed that the latent heat transfer through the deposited graphene layers allowed a larger phase transition volume and, therefore, more stress relaxation and penetration depth.

  3. An Overview on Gripping Force Measurement at the Micro and Nano-Scales Using Two-Fingered Microrobotic Systems

    Directory of Open Access Journals (Sweden)

    Mokrane Boudaoud

    2014-03-01

    Full Text Available Two-fingered micromanipulation systems with an integrated force sensor are widely used in robotics to sense and control gripping forces at the micro and nano-scales. They became of primary importance for an efficient manipulation and characterization of highly deformable biomaterials and nanostructures. This paper presents a chronological overview of gripping force measurement using two-fingered micromanipulation systems. The work summarizes the major achievements in this field from the early 90s to the present, focusing in particular on the evolution of measurement technologies regarding the requirements of microrobotic applications. Measuring forces below the microNewton for the manipulation of highly deformable materials, embedding force sensors within microgrippers to increase their dexterity, and reducing the influence of noise to improve the measurement resolution are among the addressed challenges. The paper shows different examples of how these challenges have been addressed. Resolution, operating range and signal/noise ratio of gripping force sensors are reported and compared. A discussion about force measurement technologies and gripping force control is performed and future trends are highlighted.

  4. An Overview on Gripping Force Measurement at the Micro and Nano-scales Using Two-fingered Microrobotic Systems

    Directory of Open Access Journals (Sweden)

    Mokrane Boudaoud

    2014-03-01

    Full Text Available Two-fingered micromanipulation systems with an integrated force sensor are widely used in robotics to sense and control gripping forces at the micro and nano-scales. They became of primary importance for an efficient manipulation and characterization of highly deformable biomaterials and nanostructures. This paper presents a chronological overview of gripping force measurement using two-fingered micromanipulation systems. The work summarizes the major achievements in this field from the early 90s to the present, focusing in particular on the evolution of measurement technologies regarding the requirements of microrobotic applications. Measuring forces below the microNewton for the manipulation of highly deformable materials, embedding force sensors within microgrippers to increase their dexterity, and reducing the influence of noise to improve the measurement resolution are among the addressed challenges. The paper shows different examples of how these challenges have been addressed. Resolution, operating range and signal/noise ratio of gripping force sensors are reported and compared. A discussion about force measurement technologies and gripping force control is performed and future trends are highlighted.

  5. Evaporation characteristics of thin film liquid argon in nano-scale confinement: A molecular dynamics study

    Science.gov (United States)

    Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

    2016-07-01

    Molecular dynamics simulation has been carried out to explore the evaporation characteristics of thin liquid argon film in nano-scale confinement. The present study has been conducted to realize the nano-scale physics of simultaneous evaporation and condensation inside a confined space for a three phase system with particular emphasis on the effect of surface wetting conditions. The simulation domain consisted of two parallel platinum plates; one at the top and another at the bottom. The fluid comprised of liquid argon film at the bottom plate and vapor argon in between liquid argon and upper plate of the domain. Considering hydrophilic and hydrophobic nature of top and bottom surfaces, two different cases have been investigated: (i) Case A: Both top and bottom surfaces are hydrophilic, (ii) Case B: both top and bottom surfaces are hydrophobic. For all cases, equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. Then the lower wall was set to four different temperatures such as 110 K, 120 K, 130 K and 140 K to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat fluxes normal to top and bottom walls were estimated and discussed to illuminate the effectiveness of heat transfer in both hydrophilic and hydrophobic confinement at various boundary temperatures of the bottom plate.

  6. Introducing a nano-scale crossed hot-wire for high Reynolds number measurements

    Science.gov (United States)

    Fan, Yuyang; Fu, Matthew; Hultmark, Marcus

    2016-11-01

    Hot-wire anemometry is commonly used for high Reynolds number flow measurements, mainly because of its continuous signal and high bandwidth. However, measuring two components of velocity in high Reynolds number wall-bounded flows has proven to be quite challenging with conventional crossed hot-wires, especially close to the wall, due to insufficient resolution and obstruction from the probe. The Nano-Scale Thermal Anemometry Probe (NSTAP) is a miniature hot-wire that drastically increased the spatial and temporal resolutions for single-component measurements by using a nano-scale platinum wire. Applying a novel combining method and reconfiguration of the NSTAP design, we created a sensor (x-NSTAP) that is capable of two-component velocity measurements with a sensing volume of approximately 50 × 50 × 50 μ m, providing spatial and temporal resolutions similar to the single component NSTAP. The x-NSTAP is deployed in the Superpipe facility for accurate measurements of the Reynolds stresses at very high Reynolds numbers. Supported under NSF Grant CBET-1510100 (program manager Dimitrios Papavassiliou).

  7. 3D positioning scheme exploiting nano-scale IR-UWB orthogonal pulses

    Science.gov (United States)

    Kim, Nammoon; Kim, Youngok

    2011-10-01

    In these days, the development of positioning technology for realizing ubiquitous environments has become one of the most important issues. The Global Positioning System (GPS) is a well-known positioning scheme, but it is not suitable for positioning in in-door/building environments because it is difficult to maintain line-of-sight condition between satellites and a GPS receiver. To such problem, various positioning methods such as RFID, WLAN, ZigBee, and Bluetooth have been developed for indoor positioning scheme. However, the majority of positioning schemes are focused on the two-dimension positioning even though three-dimension (3D) positioning information is more useful especially in indoor applications, such as smart space, U-health service, context aware service, etc. In this paper, a 3D positioning system based on mutually orthogonal nano-scale impulse radio ultra-wideband (IR-UWB) signals and cross array antenna is proposed. The proposed scheme uses nano-scale IR-UWB signals providing fine time resolution and high-resolution multiple signal specification algorithm for the time-of-arrival and the angle-of-arrival estimation. The performance is evaluated over various IEEE 802.15.4a channel models, and simulation results show the effectiveness of proposed scheme.

  8. An integrated nano-scale approach to profile miRNAs in limited clinical samples

    Science.gov (United States)

    Seumois, Grégory; Vijayanand, Pandurangan; Eisley, Christopher J; Omran, Nada; Kalinke, Lukas; North, Mal; Ganesan, Asha P; Simpson, Laura J; Hunkapiller, Nathan; Moltzahn, Felix; Woodruff, Prescott G; Fahy, John V; Erle, David J; Djukanovic, Ratko; Blelloch, Robert; Ansel, K Mark

    2012-01-01

    Profiling miRNA expression in cells that directly contribute to human disease pathogenesis is likely to aid the discovery of novel drug targets and biomarkers. However, tissue heterogeneity and the limited amount of human diseased tissue available for research purposes present fundamental difficulties that often constrain the scope and potential of such studies. We established a flow cytometry-based method for isolating pure populations of pathogenic T cells from bronchial biopsy samples of asthma patients, and optimized a high-throughput nano-scale qRT-PCR method capable of accurately measuring 96 miRNAs in as little as 100 cells. Comparison of circulating and airway T cells from healthy and asthmatic subjects revealed asthma-associated and tissue-specific miRNA expression patterns. These results establish the feasibility and utility of investigating miRNA expression in small populations of cells involved in asthma pathogenesis, and set a precedent for application of our nano-scale approach in other human diseases. The microarray data from this study (Figure 7) has been submitted to the NCBI Gene Expression Omnibus (GEO; http://ncbi.nlm.nih.gov/geo) under accession no. GSE31030. PMID:23304658

  9. 3D positioning scheme exploiting nano-scale IR-UWB orthogonal pulses

    Directory of Open Access Journals (Sweden)

    Kim Nammoon

    2011-01-01

    Full Text Available Abstract In these days, the development of positioning technology for realizing ubiquitous environments has become one of the most important issues. The Global Positioning System (GPS is a well-known positioning scheme, but it is not suitable for positioning in in-door/building environments because it is difficult to maintain line-of-sight condition between satellites and a GPS receiver. To such problem, various positioning methods such as RFID, WLAN, ZigBee, and Bluetooth have been developed for indoor positioning scheme. However, the majority of positioning schemes are focused on the two-dimension positioning even though three-dimension (3D positioning information is more useful especially in indoor applications, such as smart space, U-health service, context aware service, etc. In this paper, a 3D positioning system based on mutually orthogonal nano-scale impulse radio ultra-wideband (IR-UWB signals and cross array antenna is proposed. The proposed scheme uses nano-scale IR-UWB signals providing fine time resolution and high-resolution multiple signal specification algorithm for the time-of-arrival and the angle-of-arrival estimation. The performance is evaluated over various IEEE 802.15.4a channel models, and simulation results show the effectiveness of proposed scheme.

  10. Application of exergetic sustainability index to a nano-scale irreversible Brayton cycle operating with ideal Bose and Fermi gasses

    Energy Technology Data Exchange (ETDEWEB)

    Açıkkalp, Emin, E-mail: eacikkalp@gmail.com [Department of Mechanical and Manufacturing Engineering, Engineering Faculty, Bilecik S.E. University, Bilecik (Turkey); Caner, Necmettin [Department of Chemistry, Faculty of Arts and Sciences, Eskisehir Osmangazi University, Eskisehir (Turkey)

    2015-09-25

    Highlights: • An irreversible Brayton cycle operating quantum gasses is considered. • Exergetic sustainability index is derived for nano-scale cycles. • Nano-scale effects are considered. • Calculation are conducted for irreversible cycles. • Numerical results are presented and discussed. - Abstract: In this study, a nano-scale irreversible Brayton cycle operating with quantum gasses including Bose and Fermi gasses is researched. Developments in the nano-technology cause searching the nano-scale machines including thermal systems to be unavoidable. Thermodynamic analysis of a nano-scale irreversible Brayton cycle operating with Bose and Fermi gasses was performed (especially using exergetic sustainability index). In addition, thermodynamic analysis involving classical evaluation parameters such as work output, exergy output, entropy generation, energy and exergy efficiencies were conducted. Results are submitted numerically and finally some useful recommendations were conducted. Some important results are: entropy generation and exergetic sustainability index are affected mostly for Bose gas and power output and exergy output are affected mostly for the Fermi gas by x. At the high temperature conditions, work output and entropy generation have high values comparing with other degeneracy conditions.

  11. Characterization of Mechanical Properties at the Micro/Nano Scale: Stiction Failure of MEMS, High-Frequency Michelson Interferometry and Carbon NanoFibers

    Science.gov (United States)

    Kheyraddini Mousavi, Arash

    Different forces scale differently with decreasing length scales. Van der Waals and surface tension are generally ignored at the macro scale, but can become dominant at the micro and nano scales. This fact, combined with the considerable compliance and large surface areas of micro and nano devices, can leads to adhesion in MicroElectroMechanical Systems (MEMS) and NanoElectroMechanical Systems (NEMS) - a.k.a. stiction-failure. The adhesive forces between MEMS devices leading to stiction failure are characterized in this dissertation analytically and experimentally. Specifically, the adhesion energy of poly-Si μcantilevers are determined experimentally through Mode II and mixed Mode I&II crack propagation experiments. Furthermore, the description of a high-frequency Michelson Interferometer is discussed for imaging of crack propagation of the μcantilevers with their substrate at the nano-scale and harmonic imaging of MEMS/NEMS. Van der Waals forces are also responsible for the adhesion in nonwoven carbon nanofiber networks. Experimental and modeling results are presented for the mechanical and electrical properties of nonwoven (random entanglements) of carbon nanofibers under relatively low and high-loads, both in tensions and compression. It was also observed that the structural integrity of these networks is controlled by mechanical entanglement and flexural rigidity of individual fibers as well as Hertzian forces at the fiber/fiber interface.

  12. Effect of Nano-Scale and Micro-Scale Yttria Reinforcement on Powder Forged AA-7075 Composites

    Science.gov (United States)

    Joshi, Tilak C.; Prakash, U.; Dabhade, Vikram V.

    2016-05-01

    The present investigation deals with the development of AA-7075 metal matrix composites reinforced with nano yttria particles (0.1 to 3 vol.%) and micron yttria particles (1 to 15 vol.%) by powder forging. Matrix powders (AA-7075) and reinforcement powders (yttria) were blended, cold compacted, sintered under pure nitrogen, and finally hot forged in a closed floating die. The hot forged samples were artificially age hardened at 121 °C for various time durations to determine the peak aging time. The mechanical properties in the peak-aged condition as well as density and microstructure were determined and correlated with the reinforcement size and content. The nano composites exhibited a well-densified structure as well as better hardness and tensile/compressive strength as compared to micro-scale composites. The mechanical properties in nano-scale composites peaked at 0.5 vol.% yttria addition while for micro-scale composites these properties peaked at 5 vol.% yttria addition.

  13. The influence of nano-scale second-phase particles on deformation of fine grained calcite mylonites

    Science.gov (United States)

    Herwegh, Marco; Kunze, Karsten

    2002-09-01

    Grey and white carbonate mylonites were collected along thrust planes of the Helvetic Alps. They are characterised by very small grain sizes and non-random grain shape (SPO) and crystallographic preferred orientation (CPO). Presumably they deformed in the field of grain size sensitive flow by recrystallisation accommodated intracrystalline deformation in combination with granular flow. Both mylonites show a similar mean grain size, but in the grey mylonites the grain size range is larger, the grain shapes are more elongate and the dynamically recrystallised calcite grains are more often twinned. Grey mylonites have an oblique CPO, while the CPO in white mylonites is symmetric with respect to the shear plane. Combustion analysis and TEM investigations revealed that grey mylonites contain a higher amount of highly structured kerogens with particle sizes of a few tens of nanometers, which are finely dispersed at the grain boundaries. During deformation of the rock, nano-scale particles reduced the migration velocity of grain boundaries by Zener drag resulting in slower recrystallisation rates of the calcite aggregate. In the grey mylonites, more strain increments were accommodated by individual grains before they became refreshed by dynamic recrystallisation than in white mylonites, where grain boundary migration was less hindered and recrystallisation cycles were faster. Consequently, grey mylonites represent 'deformation' microfabrics while white mylonites are characterised by 'recrystallisation' microfabrics. Field geologists must utilise this different deformation behavior when applying the obliquity in CPO and SPO of the respective mylonites as reliable shear sense indicators.

  14. Nano-Scale Secondary Ion Mass Spectrometry: Potential And Pitfalls Of This Technique For Soil Organic Matter Stabilization

    Science.gov (United States)

    Herrmann, A. M.

    2007-12-01

    The mechanisms by which organic matter is stabilized in soils are still poorly understood, and it is notable that some postulated mechanisms are currently only weakly supported by data. A major obstacle to progress is the lack of techniques of adequate sensitivity and resolution for data collection needed to further our understanding of soil organic matter stabilization at relevant scales. Nano-Secondary Ion Mass Spectrometry (NanoSIMS) is a cutting edge technology linking high resolution microscopy with isotopic analysis, which allows precise, spatially-explicit, elemental and isotopic analysis at micro-and nanoscale. The power of NanoSIMS lies in the ability of the instrument to distinguish stable isotopes of elements with a high sensitivity, i.e. concentrations in parts per million can be detected. The level of spatial resolution achievable is better than 50 nm (133Cs+ primary beam) with NanoSIMS, a significant improvement on other SIMS instruments and on X-ray micro-analytical techniques. These instruments have been applied to studies of presolar materials from meteorites, in material science, geology and mineralogy as well as biology. Recently, the potential of NanoSIMS has been demonstrated to explore in situ the biophysical interface in soils (Herrmann et al., 2007). I will present recent findings illustrating the capacity of NanoSIMS to improve our fundamental understanding of soil processes at the nano- and micro-scale, along with my experiences in the methodological approaches that need consideration with respect to experimental design and sample preparation. Herrmann, AM, Clode, PL, Fletcher, IR, Nunan N, Stockdale, EA, O'Donnell, AG, Murphy, DV, 2007. A novel method for the study of the biophysical interface in soils using nano-scale secondary ion mass spectrometry. Rapid Communications in Mass Spectrometry 21, 29-34.

  15. Fabrication of ordered micro- and nano-scale patterns based on optical discs and nanoimprint

    Science.gov (United States)

    Guo, Hui-jing; Zhang, Xiao-liang; Li, Xiao-chun

    2016-07-01

    A simple method to fabricate one-dimensional (1-D) and two-dimensional (2-D) ordered micro- and nano-scale patterns is developed based on the original masters from optical discs, using nanoimprint technology and soft stamps. Polydimethylsiloxane (PDMS) was used to replicate the negative image of the 1-D grating pattern on the masters of CD-R, DVD-R and BD-R optical discs, respectively, and then the 1-D pattern on one of the PDMS stamps was transferred to a blank polycarbonate (PC) substrate by nanoimprint. The 2-D ordered patterns were fabricated by the second imprinting using another PDMS stamp. Different 2-D periodic patterns were obtained depending on the PDMS stamps and the angle between the two times of imprints. This method may provide a way for the fabrication of complex 2-D patterns using simple 1-D masters.

  16. Nano-scaled diffusional or dislocation creep analysis of single-crystal ZnO

    Directory of Open Access Journals (Sweden)

    P. H. Lin

    2016-09-01

    Full Text Available The nanoindentation time-dependent creep experiments with different peak loads are conducted on c-plane (0001, a-plane (112¯0 and m-plane (101¯0 of single-crystal ZnO. Under nano-scaled indentation, the creep behavior is crystalline orientation-dependent. For the creep on (0001, the stress exponent at low loads is ∼1 and at high loads ∼4. The stress exponents under all loads are within 3∼7 for the creep on (112¯0 and (101¯0. This means that diffusion mechanism and dislocation mechanism is operative for different planes and loads. The relative difficulty of dislocations activation is an additional factor leading to the occurring of diffusion creep on the c-plane of single-crystal ZnO.

  17. A New Reforming Reaction Mechanism of Carbon Dioxide with Methane on Nano Scale Nickel catalyst

    Directory of Open Access Journals (Sweden)

    Long Wei

    2016-01-01

    Full Text Available The reforming mechanism of CO2-CH4 on Nano scale Ni metal catalyst was investigated using the B3LYP density functional method and MP2/Lanl2dz method. It was found that the reaction include thirteen steps and the activation energy of each step was 44.7175, 200.4707, 171.0781, 307.2596, 124.5252, 330.7904, 593.9056, 177.5526, 226.6793, 277.789 2, 394.5525,399.5340 and 105.4115 kJ·mol−1. The rate determining step was the fourth step. The enthalpy value of each step was 31.6136, 106.7138, −104.2589, 79.9641, 93.5573,174.6 121, 259.6409, −141.9192, −439.9338, −265.4756, −208.3245, 131.6561 and −86.1765 kJ·mol−1.

  18. Effects of nano-scaled fish bone on the gelation properties of Alaska pollock surimi.

    Science.gov (United States)

    Yin, Tao; Park, Jae W

    2014-05-01

    Gelation properties of Alaska pollock surimi as affected by addition of nano-scaled fish bone (NFB) at different levels (0%, 0.1%, 0.25%, 0.5%, 1% and 2%) were investigated. Breaking force and penetration distance of surimi gels after setting increased significantly as NFB concentration increased up to 1%. The first peak temperature and value of storage modulus (G'), which is known to relate to the unfolding and aggregation of light meromyosin, increased as NFB concentration increased. In addition, 1% NFB treatment demonstrated the highest G' after gelation was completed. The activity of endogenous transglutaminase (TGase) in Alaska pollock surimi increased as NFB calcium concentration increased. The intensity of myosin heavy chain cross-links also increased as NFB concentration increased indicating the formation of more ε-(γ-glutamyl) lysine covalent bond by endogenous TGase and calcium ions from NFB. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Turbulence measurements in pipe flow using a nano-scale thermal anemometry probe

    Energy Technology Data Exchange (ETDEWEB)

    Vallikivi, M.; Hultmark, M.; Smits, A.J. [Princeton University, Department of Mechanical and Aerospace Engineering, Princeton, NJ (United States); Bailey, S.C.C. [University of Kentucky, Department of Mechanical Engineering, Lexington, KY (United States)

    2011-12-15

    A new nano-scale thermal anemometry probe (NSTAP) has been developed using a novel procedure based on deep reactive ion etching. The performance of the new probe is shown to be superior to that of the previous design by Bailey (J Fluid Mech 663:160-179, 2010). It is then used to measure the streamwise velocity component of fully developed turbulent pipe flow, and the results are compared with data obtained using conventional hot-wire probes. The NSTAP agrees well with the hot-wire at low Reynolds numbers, but it is shown that it has better spatial resolution and frequency response. The data demonstrate that significant spatial filtering effects can be seen in the hot-wire data for probes as small as 7 viscous units in length. (orig.)

  20. Morphology of Nano-scale Silica and Titania from Flames Distorted by Electric Coronas

    Science.gov (United States)

    Hyeon-Lee, J.; Beaucage, G.; Vemury, S.; Pratsinis, S.

    1997-03-01

    Flame synthesis of ultrafine titania and silica particles in the presence of a gaseous electric discharge leads to nano-sized powders with controlled size and crystallinity. Charging during particle formation reduces the particle size and narrows the size distribution, breaking the limit posed by the self-preserving theory for coagulation (S. Vemur, S. E. Pratsinis, Appl. Phys. Lett. 66, 2275-7 (1995)). The work presented here focuses on the nano-scale morphology of these ultrafine particles using microscopy, SAXS and Bonse-Hart SAXS. The powders form mass-fractal morphologies with variation in the primary particle, mass-fractal dimension and aggregate size with the electric discharge strength. Under some conditions the particles display a transition from mass to surface fractal.

  1. Investigation of MEMS force sensors for nano-scale water measurements

    Science.gov (United States)

    Kwon, Soyoung; Jhe, Wonho; Stambaugh, Corey

    2011-03-01

    Nanoscale water formed by capillary condensation has typically been studied by means of an atomic force microscope (AFM). While this approach can provide details about the dynamic visco-elastic properties, it is limited in the type of information that can be measured. Here we propose replacing the fixed sample surface generally used in AFM systems with movable micro-mechanical force sensors (MEMS) fabricated specifically for tapping mode or shear mode. By incorporating a MEMS device we can directly measure the adhesion force, pull-in distance and capillary force of nano confined water while the AFM collects information pertaining to the dynamic visco-elastic properties. In this talk, we will characterize the force measurement in the system and discuss the behavior of the device in the presence of nano-scale water. Work supported NRF of Korea and NSF grant OISE #0853104.

  2. A combined method for correlative 3D imaging of biological samples from macro to nano scale

    Science.gov (United States)

    Kellner, Manuela; Heidrich, Marko; Lorbeer, Raoul-Amadeus; Antonopoulos, Georgios C.; Knudsen, Lars; Wrede, Christoph; Izykowski, Nicole; Grothausmann, Roman; Jonigk, Danny; Ochs, Matthias; Ripken, Tammo; Kühnel, Mark P.; Meyer, Heiko

    2016-10-01

    Correlative analysis requires examination of a specimen from macro to nano scale as well as applicability of analytical methods ranging from morphological to molecular. Accomplishing this with one and the same sample is laborious at best, due to deformation and biodegradation during measurements or intermediary preparation steps. Furthermore, data alignment using differing imaging techniques turns out to be a complex task, which considerably complicates the interconnection of results. We present correlative imaging of the accessory rat lung lobe by combining a modified Scanning Laser Optical Tomography (SLOT) setup with a specially developed sample preparation method (CRISTAL). CRISTAL is a resin-based embedding method that optically clears the specimen while allowing sectioning and preventing degradation. We applied and correlated SLOT with Multi Photon Microscopy, histological and immunofluorescence analysis as well as Transmission Electron Microscopy, all in the same sample. Thus, combining CRISTAL with SLOT enables the correlative utilization of a vast variety of imaging techniques.

  3. Optimizing Cr(VI) and Tc(VII) remediation through nano-scale biomineral engineering

    Energy Technology Data Exchange (ETDEWEB)

    Cutting, R. S.; Coker, V. S.; Telling, N. D.; Kimber, R. L.; Pearce, C. I.; Ellis, B.; Lawson, R; van der Laan, G.; Pattrick, R.A.D.; Vaughan, D.J.; Arenholz, E.; Lloyd, J. R.

    2009-09-09

    To optimize the production of biomagnetite for the bioremediation of metal oxyanion contaminated waters, the reduction of aqueous Cr(VI) to Cr(III) by two biogenic magnetites and a synthetic magnetite was evaluated under batch and continuous flow conditions. Results indicate that nano-scale biogenic magnetite produced by incubating synthetic schwertmannite powder in cell suspensions of Geobacter sulfurreducens is more efficient at reducing Cr(VI) than either biogenic nano-magnetite produced from a suspension of ferrihydrite 'gel' or synthetic nano-scale Fe{sub 3}O{sub 4} powder. Although X-ray Photoelectron Spectroscopy (XPS) measurements obtained from post-exposure magnetite samples reveal that both Cr(III) and Cr(VI) are associated with nanoparticle surfaces, X-ray Magnetic Circular Dichroism (XMCD) studies indicate that some Cr(III) has replaced octahedrally coordinated Fe in the lattice of the magnetite. Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) measurements of total aqueous Cr in the associated solution phase indicated that, although the majority of Cr(III) was incorporated within or adsorbed to the magnetite samples, a proportion ({approx}10-15 %) was released back into solution. Studies of Tc(VII) uptake by magnetites produced via the different synthesis routes also revealed significant differences between them as regards effectiveness for remediation. In addition, column studies using a {gamma}-camera to obtain real time images of a {sup 99m}Tc(VII) radiotracer were performed to visualize directly the relative performances of the magnetite sorbents against ultra-trace concentrations of metal oxyanion contaminants. Again, the magnetite produced from schwertmannite proved capable of retaining more ({approx}20%) {sup 99m}Tc(VII) than the magnetite produced from ferrihydrite, confirming that biomagnetite production for efficient environmental remediation can be fine-tuned through careful selection of the initial Fe(III) mineral

  4. Radiation effects on structural materials

    Energy Technology Data Exchange (ETDEWEB)

    Ghoniem, N.M.

    1991-06-28

    This report discusses the following topics on the effect radiation has on thermonuclear reactor materials: Atomic Displacements; Microstructure Evolution; Materials Engineering, Mechanics, and Design; Research on Low-Activation Steels; and Research Motivated by Grant Support.

  5. Materials research at Stanford University. [composite materials, crystal structure, acoustics

    Science.gov (United States)

    1975-01-01

    Research activity related to the science of materials is described. The following areas are included: elastic and thermal properties of composite materials, acoustic waves and devices, amorphous materials, crystal structure, synthesis of metal-metal bonds, interactions of solids with solutions, electrochemistry, fatigue damage, superconductivity and molecular physics and phase transition kinetics.

  6. Materials Science and Physics at Micro/Nano-Scales. FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Judy Z

    2009-09-07

    The scope of this project is to study nanostructures of semiconductors and superconductors, which have been regarded as promising building blocks for nanoelectronic and nanoelectric devices. The emphasis of this project is on developing novel synthesis approaches for fabrication of nanostructures with desired physical properties. The ultimate goal is to achieve a full control of the nanostructure growth at microscopic scales. The major experimental achievements obtained are summarized

  7. The electrical conductivity characteristics of Fe/Cu nano-scale multilayer materials

    Institute of Scientific and Technical Information of China (English)

    JIN; Xuesong

    2001-01-01

    [1]Schmidt, R., Multiple emitter location and signal parameter estimation, IEEE Trans., 1986, AP-34(2): 267.[2]Ziskind, I., Wax, M., Maximum likelihood localization of multiple sources by alternating projection, IEEE Trans., 1988, ASSP-36(10): 1553.[3]Viberg, M., Ottersten, B., Detection and estimation in sensor arrays using weighted subspace fitting, IEEE Trans., 1991, SP-39(11): 2431.[4]Shan, T., Wax, M., Kailath, T. K., On spatial smoothing for direction of arrival estimation of coherent signals, IEEE Trans., 1985, ASSP-33(4): 806.[5]Williams, R. T., An improved spatial smoothing technique for bearing estimation on a multipath environment, IEEE Trans., 1989, ASSP-36(4): 425.[6]Zoltowski, M. D., Mathews, C. P., Real-time frequency and 2-D angle estimation with sub-nyquist spatio-temporal sampling, IEEE Trans., 1994, SP-42(10): 2781.[7]Haykin, S., P. Reiliy, J., Kezys, V. et al., Some aspects of array signal processing, IEEE Proc. F., 1992, 139(1): 1.[8]Eiges, R., Griffiths, H. D., Mode-space spatial spectral estimation for circular arrays, IEEE Proc. Radar, Sonar Navig., 1994, 14(6): 300.[9]Friedlander, B., Direction finding using spatial smoothing with interpolated arrays, IEEE Trans., 1992, AES-28(2): 574.[10]Cadzow, J. A., Signal enhancement——a composite property mapping algorithm, IEEE Trans., 1988, ASSP-36(1): 49.[11]Stoica, P., Nehorai, A., MUSIC, Maximum likelihood, and Cramer-Rao bound, ASSP-37, 1989, IEEE Trans. on ASSP-37(5): 720.

  8. A novel nano-scale non-contact temperature measurement technique for crystalline materials.

    Science.gov (United States)

    Wu, Xiaowei; Hull, Robert

    2012-11-23

    A new high spatial resolution non-contact temperature measurement technique (thermal scanning electron microscopy, ThSEM) is demonstrated. It employs temperature dependent thermal diffuse scattering in electron backscatter diffraction (EBSD) in a scanning electron microscope (SEM). Unlike conventional scanning thermal microscopy, which uses contact probes, ThSEM is a non-contact method. In contrast to optical temperature mapping techniques, ThSEM does not have the spatial resolution limitation that arises from the optical wavelength and theoretically can reach a resolution of <10 nm. The hardware setup is very similar to the EBSD system in an SEM, which can make the integration of temperature mapping into an SEM relatively straightforward. Moreover, multiple signals or contrast mechanisms, such as temperature distributions, grain orientation maps, topographic images and elemental maps can be obtained from the same sample area depending on the specific SEM capability. This technique thus adds a new channel-the temperature signal-to the collection of existing SEM signals.

  9. NASICON-Structured Materials for Energy Storage.

    Science.gov (United States)

    Jian, Zelang; Hu, Yong-Sheng; Ji, Xiulei; Chen, Wen

    2017-05-01

    The demand for electrical energy storage (EES) is ever increasing, which calls for better batteries. NASICON-structured materials represent a family of important electrodes due to its superior ionic conductivity and stable structures. A wide range of materials have been considered, where both vanadium-based and titanium-based materials are recommended as being of great interest. NASICON-structured materials are suitable for both the cathode and the anode, where the operation potential can be easily tuned by the choice of transition metal and/or polyanion group in the structure. NASICON-structured materials also represent a class of solid electrolytes, which are widely employed in all-solid-state ion batteries, all-solid-state air batteries, and hybrid batteries. NASICON-structured materials are reviewed with a focus on both electrode materials and solid-state electrolytes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Bio-inspired variable structural color materials.

    Science.gov (United States)

    Zhao, Yuanjin; Xie, Zhuoying; Gu, Hongcheng; Zhu, Cun; Gu, Zhongze

    2012-04-21

    Natural structural color materials, especially those that can undergo reversible changes, are attracting increasing interest in a wide variety of research fields. Inspired by the natural creatures, many elaborately nanostructured photonic materials with variable structural colors were developed. These materials have found important applications in switches, display devices, sensors, and so on. In this critical review, we will provide up-to-date research concerning the natural and bio-inspired photonic materials with variable structural colors. After introducing the variable structural colors in natural creatures, we will focus on the studies of artificial variable structural color photonic materials, including their bio-inspired designs, fabrications and applications. The prospects for the future development of these fantastic variable structural color materials will also be presented. We believe this review will promote the communications among biology, bionics, chemistry, optical physics, and material science (196 references).

  11. Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Guangze; Luo, Dian; Fan, Guohua [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin, E-mail: maxin@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-05-01

    Highlights: • Ta alloying layer are fabricated by magnetron sputtering and high current pulsed electron beam. • Nano-scaled TaC precipitates forms within the δ-Fe grain after tempering treatment. • The mean diameter of TaC particles is about 5–8 nm. • The hardness of alloying layer increased by over 50% after formation of nano-scaled TaC particle. - Abstract: In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

  12. Structural Materials for Innovative Nuclear Systems

    Energy Technology Data Exchange (ETDEWEB)

    Yvon, Pascal [Commissariat a l' energie atomique - CEA (France)

    2011-07-01

    This series of slides deal with: the goals for advanced fission reactor systems; the requirements for structural materials; a focus on two important types of materials: ODS and CMC; a focus on materials under irradiation (multiscale modelling, experimental simulation, 'smart' experiments in materials testing reactors); some concluding remarks.

  13. Building Investigation: Material or Structural Performance

    Directory of Open Access Journals (Sweden)

    Yusof M.Z.

    2014-03-01

    Full Text Available Structures such as roof trusses will not suddenly collapse without ample warning such as significant deflection, tilting etc. if the designer manages to avoid the cause of structural failure at the material level and the structural level. This paper outlines some principles and procedures of PDCA circle and QC tools which can show some clues of structural problems in terms of material or structural performance

  14. Composite Materials for Structural Design.

    Science.gov (United States)

    1982-03-01

    Introduction to Composite Materials , Technomic, Westport, Connecticut, 1980, pp. 19-20, 388-401. 8. W.D. Bascom, J.L. Bitner, R.J. Moulton, and A.R. Siebert...34 Introduction to Composite Materials ", Technomic Publishing Co., pp. 8-18,(1980). [6] Beckwith, S. W., "Viscoelastic Characterization of a Nonlinear Glass

  15. Laser direct writing of micro- and nano-scale medical devices

    OpenAIRE

    Gittard, Shaun D; Narayan, Roger J.

    2010-01-01

    Laser-based direct writing of materials has undergone significant development in recent years. The ability to modify a variety of materials at small length scales and using short production times provides laser direct writing with unique capabilities for fabrication of medical devices. In many laser-based rapid prototyping methods, microscale and submicroscale structuring of materials is controlled by computer-generated models. Various laser-based direct write methods, including selective las...

  16. Field- to nano-scale evidence for weakening mechanisms along the fault of the 2016 Amatrice and Norcia earthquakes, Italy

    Science.gov (United States)

    Smeraglia, Luca; Billi, Andrea; Carminati, Eugenio; Cavallo, Andrea; Doglioni, Carlo

    2017-08-01

    In August and October 2016, two normal fault earthquakes (Mw 6.0 and Mw 6.5, respectively) struck the Amatrice-Norcia area in the central Apennines, Italy. The mainshocks nucleated at depths of 7-9 km with the co-seismic slip propagating upward along the Mt. Gorzano Fault (MGF) and Mt. Vettore Fault System (MVFS). To recognize possible weakening mechanisms along the carbonate-hosted seismogenic faults that generated the Amatrice-Norcia earthquakes, the fresh co-seismic fault exposure (i.e., ;nastrino;) exposed along the Mt. Vettoretto Fault was sampled and analyzed. This exposed fault belongs to the MVFS and was exhumed from 2-3 km depth. Over the fresh fault surface, phyllosilicates concentrated and localized along mm- to μm-thick layers, and truncated clasts and fluid-like structures were found. At the nano-scale, instead of their common platy-lamellar crystallographic texture, the analyzed phyllosilicates consist of welded nm-thick nanospherules and nanotubes similar to phyllosilicates deformed in rotary shear apparatus at seismic velocities or altered under high hydrothermal temperatures (> 250 °C). Moreover, the attitude of the Mt. Vettoretto Fault and its kinematics inferred from exposed slickenlines are consistent with the co-seismic fault and slip vectors obtained from the focal mechanisms computed for the 2016 mainshocks. All these pieces of evidence suggest that the Mt. Vettoretto Fault slipped seismically during past earthquakes and that co-seismic slip was assisted and facilitated at depths of < 3 km by phyllosilicate-rich layers and overpressured fluids. The same weakening processes may also have been decisive in facilitating the co-seismic slip propagation during the 2016 Mw 6.0 Amatrice and Mw 6.5 Norcia earthquakes. The microstructures found along the Mt. Vettoretto Fault, which is certainly a seismogenic fault, provide a realistic synoptic picture of co-seismic processes and weakening mechanisms that may occur in carbonate-hosted seismogenic

  17. Hierarchical Engineered Materials and Structures

    Science.gov (United States)

    2012-11-30

    Kheng, A. Kaushik, Y. Qi, H. Kim, S. Noh, E. Arruda, A. Waas, N. Kotov. Highly Ductile Multilayered Films by Layer-by-Layer Assembly of Oppositely...940, 1983. [2] Z. Bažant and B. Oh, "Crack band theory for fracture of concrete ," Materials and Struc- tures, Vol. 16, pp. 155-177, 1983. [3] W.E Baker... concrete ," Heron, Vol. 30, No. 1, 1985. [27] C. W. Schwingshackl, G. S. Aglietti and P. R. Cunningham, "Determination of honey- comb material properties

  18. Single-electron tunneling by using a two-dimensional Corbino nano-scale disk

    Energy Technology Data Exchange (ETDEWEB)

    Taira, H., E-mail: taira.hisao@s.hokkyodai.ac.jp [Faculty of Education, Hokkaido University of Education, Kita-ku, Sapporo 002-8502 (Japan); Suzuki, A., E-mail: asuzuki@rs.kagu.tus.ac.jp [Department of Physics, Faculty of Science, Tokyo University of Science, Tokyo 162-8601 (Japan)

    2015-09-15

    We investigate a single-electron tunneling effect of two-dimensional electron systems formed in the Corbino nano-scale disk. By controlling bias and gate voltages, the transistor using this effect is able to control electrons one by one. The present study focuses on the electronic transmission probability affected by the charging energy in the Corbino-type single-electron transistor. We reformulated the Schrödinger equation for an electron in the Corbino disk in order to consider the effect of the curvature of the disk, taking into account the charging effect on the performance of the Corbino-type single-electron transistor. We formulated the transmission probability of the electron by applying the Wentzel-Kramers-Brillouin (WKB) method. The electron’s energy in the formula of the transmission probability is then associated to the energy eigenvalue of the Schrödinger equation for an electron in an effective confining potential. We numerically solved the Schrödinger equation to evaluate the transmission probability. Our results show that the transmission probability strongly depends on the charging energy stored in the Corbino disk depending on its size.

  19. Design and test challenges in Nano-scale analog and mixed CMOS technology

    Directory of Open Access Journals (Sweden)

    Mouna Karmani

    2011-07-01

    Full Text Available The continuous increase of integration densities in Complementary Metal–Oxide–Semiconductor (CMOStechnology has driven the rapid growth of very large scale integrated (VLSI circuit for today's high-techelectronics industries from consumer products to telecommunications and computers. As CMOStechnologies are scaled down into the nanometer range, analog and mixed integrated circuit (IC design andtesting have become a real challenge to ensure the functionality and quality of the product. The first part ofthe paper presents the CMOS technology scaling impact on design and reliability for consumer and criticalapplications. We then propose a discussion on the role and challenges of testing analog and mixed devicesin the nano-scale era. Finally we present the IDDQ testing technique used to detect the most likely defects ofbridging type occurring in analog CMOS circuits during the manufacturing process and creating a resistivepath between VDD supply and the ground.To prove the efficiency of the proposed technique we design a CMOS 90nm operational amplifier (Opamp and a Built in Current Sensor (BICS to validate the technique and correlate it with post layoutsimulation results.

  20. Design and test challenges in Nano-scale analog and mixed CMOS technology

    Directory of Open Access Journals (Sweden)

    Mouna Karmani

    2011-06-01

    Full Text Available The continuous increase of integration densities in Complementary Metal–Oxide–Semiconductor (CMOStechnology has driven the rapid growth of very large scale integrated (VLSI circuit for today's high-tech electronics industries from consumer products to telecommunications and computers. As CMOS technologies are scaled down into the nano meter range, analog and mixed integrated circuit (IC design and testing have become a real challenge to ensure the functionality and quality of the product. The first part of the paper presents the CMOS technology scaling impact on design and reliability for consumer and critical applications. We then propose a discussion on the role and challenges of testing analog and mixed devices in the nano-scale era. Finally we present the IDDQ testing technique used to detect the most likely defects of bridging type occurring in analog CMOS circuits during the manufacturing process and creating a resistive path between VDD supply and the ground.To prove the efficiency of the proposed technique we design a CMOS 90nm operational amplifier (Opamp and a Built in Current Sensor (BICS to validate the technique and correlate it with post layout simulation results.

  1. Analysis and Correction of Dynamic Geometric Misalignment for Nano-Scale Computed Tomography at BSRF.

    Directory of Open Access Journals (Sweden)

    Jian Fu

    Full Text Available Due to its high spatial resolution, synchrotron radiation x-ray nano-scale computed tomography (nano-CT is sensitive to misalignments in scanning geometry, which occurs quite frequently because of mechanical errors in manufacturing and assembly or from thermal expansion during the time-consuming scanning. Misalignments degrade the imaging results by imposing artifacts on the nano-CT slices. In this paper, the geometric misalignment of the synchrotron radiation nano-CT has been analyzed by partial derivatives on the CT reconstruction algorithm and a correction method, based on cross correlation and least-square sinusoidal fitting, has been reported. This work comprises a numerical study of the method and its experimental verification using a dataset measured with the full-field transmission x-ray microscope nano-CT at the beamline 4W1A of the Beijing Synchrotron Radiation Facility. The numerical and experimental results have demonstrated the validity of the proposed approach. It can be applied for dynamic geometric misalignment and needs neither phantom nor additional correction scanning. We expect that this method will simplify the experimental operation of synchrotron radiation nano-CT.

  2. Nano-scale islands of ruthenium oxide as an electrochemical sensor for iodate and periodate determination.

    Science.gov (United States)

    Chatraei, Fatemeh; Zare, Hamid R

    2013-03-01

    In this study, a promising electrochemical sensor was fabricated by the electrodeposition of nano-scale islands of ruthenium oxide (ruthenium oxide nanoparticles, RuON) on a glassy carbon electrode (RuON-GCE). Then, the electrocatalytic oxidation of iodate and periodate was investigated on it, using cyclic voltammetry, chronoamperometry and amperometry as diagnostic techniques. The charge transfer coefficient, α, and the charge transfer rate constant, ks, for electron transfer between RuON and GCE were calculated as 0.5 ± 0.03 and 9.0 ± 0.7 s(-1) respectively. A comparison of the data obtained from the electrocatalytic reduction of iodate and periodate at a bare GCE (BGCE) and RuON-GCE clearly shows that the unique electronic properties of nanoparticles definitely improve the characteristics of iodate and periodate electrocatalytic reduction. The kinetic parameters such as the electron transfer coefficient, α, and the heterogeneous electron transfer rate constant, k', for the reduction of iodate and periodate at RuON-GCE surface were determined using cyclic voltammetry. Amperometry revealed a good linear relationship between the peak current and the concentration of iodate and periodate. The detection limits of 0.9 and 0.2 μM were calculated for iodate and periodate respectively.

  3. Improvements of a nano-scale crossed hot-wire for high Reynolds number measurements

    Science.gov (United States)

    Fan, Yuyang; Hultmark, Marcus

    2015-11-01

    Hot-wire anemometry, despite its limited spatial and temporal resolution, is still the preferred tool for high Reynolds number flow measurements, mainly due to the continuous signal. To address the resolution issues, the Nano-Scale Thermal Anemometry Probe (NSTAP) was developed at Princeton University. The NSTAP has a sensing volume more than one order of magnitude smaller than conventional hot-wires, and it has displayed superior performance. However, the NSTAP can only measure a single component of the velocity. Using a novel combining method, a probe that enables two-component velocity measurements has been created (the x-NSTAP). The measurement volume is approximately 50 × 50 × 50 μ m, more than one order of magnitude smaller in all directions compared to conventional crossed hot-wires. The x-NSTAP has been further improved to allow more accurate measurements with the help of flow visualization using a scaled model but matching Reynolds number. Results from turbulent flow measurements with the new x-NSTAP are also presented. Supported under NSF grant CBET-1510100 (program manager Dimitrios Papavassiliou).

  4. Quasicontinuum simulations of geometric effect on onset plasticity of nano-scale patterned lines

    Science.gov (United States)

    Jin, Jianfeng; Cao, Jingyi; Zhou, Siyuan; Yang, Peijun; Guo, Zhengxiao

    2017-09-01

    Onset plasticity of metallic nano-lines or nano-beams is of considerable scientific and technological interest in micro-/nano- mechanics and interconnects of patterned lines in electronic devices, where capability of resistance to deformation is important. In this study, a multiscale quasicontinuum (QC) method was used to explore such an issue in a nano-scale copper (Cu) line protruding from a relatively large single crystal Cu substrate during compression. The results show that the yield stress of a rectangular beam on the substrate can be greatly reduced compared with that of a flat surface of the same area. For the rectangular line, the aspect ratio (width/height) affects dislocation morphology at the onset plasticity without much change of yield stress. However, for the trapezoidal line, the yield stress decreases with the base angle (α), especially when the α is over 54.7°. As the sidewall orientation changes from at α = 0°, then to at α = 54.7° and finally to at α = 90°, a higher surface energy could enable easier dislocation formation and lower yield stress. Meanwhile, it is found that the interaction between the line and the support substrate also shows a great effect on yield stress. Moreover, although it is possible to open two extra dislocation slip planes inside from the two bottom corners of the Cu line with the α over 54.7°, dislocation nucleation derived from them is only observed at α = 90°.

  5. Nano-scale chemical evolution in a proton-and neutron-irradiated Zr alloy

    Science.gov (United States)

    Harte, Allan; Topping, M.; Frankel, P.; Jädernäs, D.; Romero, J.; Hallstadius, L.; Darby, E. C.; Preuss, M.

    2017-04-01

    Proton-and neutron-irradiated Zircaloy-2 are compared in terms of the nano-scale chemical evolution within second phase particles (SPPs) Zr(Fe,Cr)2 and Zr2(Fe,Ni). This is accomplished through ultra-high spatial resolution scanning transmission electron microscopy and the use of energy-dispersive X-ray spectroscopic methods. Fe-depletion is observed from both SPP types after irradiation with both irradiative species, but is heterogeneous in the case of Zr(Fe,Cr)2, predominantly from the edge region, and homogeneously in the case of Zr2(Fe,Ni). Further, there is evidence of a delay in the dissolution of the Zr2(Fe,Ni) SPP with respect to the Zr(Fe,Cr)2. As such, SPP dissolution results in matrix supersaturation with solute under both irradiative species and proton irradiation is considered well suited to emulate the effects of neutron irradiation in this context. The mechanisms of solute redistribution processes from SPPs and the consequences for irradiation-induced growth phenomena are discussed.

  6. Nano-scale characterization of the dynamics of the chloroplast Toc translocon.

    Science.gov (United States)

    Reddick, L Evan; Chotewutmontri, Prakitchai; Crenshaw, Will; Dave, Ashita; Vaughn, Michael; Bruce, Barry D

    2008-01-01

    Translocons are macromolecular nano-scale machines that facilitate the selective translocation of proteins across membranes. Although common in function, different translocons have evolved diverse molecular mechanisms for protein translocation. Subcellular organelles of endosymbiotic origin such as the chloroplast and mitochondria had to evolve/acquire translocons capable of importing proteins whose genes were transferred to the host genome. These gene products are expressed on cytosolic ribosomes as precursor proteins and targeted back to the organelle by an N-terminal extension called the transit peptide or presequence. In chloroplasts the transit peptide is specifically recognized by the Translocon of the Outer Chloroplast membrane (Toc) which is composed of receptor GTPases that potentially function as gate-like switches, where GTP binding and hydrolysis somehow facilitate preprotein binding and translocation. Compared to other translocons, the dynamics of the Toc translocon are probably more complex and certainly less understood. We have developed biochemical/biophysical, imaging, and computational techniques to probe the dynamics of the Toc translocon at the nanoscale. In this chapter we provide detailed protocols for kinetic and binding analysis of precursor interactions in organeller, measurement of the activity and nucleotide binding of the Toc GTPases, native electrophoretic analysis of the assembly/organization of the Toc complex, visualization of the distribution and mobility of Toc apparatus on the surface of chloroplasts, and conclude with the identification and molecular modeling Toc75 POTRA domains. With these new methodologies we discuss future directions of the field.

  7. Development of a Cryostat to Characterize Nano-scale Superconducting Quantum Interference Devices

    Science.gov (United States)

    Longo, Mathew; Matheny, Matthew; Knudsen, Jasmine

    2016-03-01

    We have designed and constructed a low-noise vacuum cryostat to be used for the characterization of nano-scale superconducting quantum interference devices (SQUIDs). Such devices are very sensitive to magnetic fields and can measure changes in flux on the order of a single electron magnetic moment. As a part of the design process, we calculated the separation required between the cryogenic preamplifier and superconducting magnet, including a high-permeability magnetic shield, using a finite-element model of the apparatus. The cryostat comprises a vacuum cross at room temperature for filtered DC and shielded RF electrical connections, a thin-wall stainless steel support tube, a taper-sealed cryogenic vacuum can, and internal mechanical support and wiring for the nanoSQUID. The Dewar is modified with a room-temperature flange with a sliding seal for the cryostat. The flange supports the superconducting 3 Tesla magnet and thermometry wiring. Upon completion of the cryostat fabrication and Dewar modifications, operation of the nanoSQUIDs as transported from our collaborator's laboratory in Israel will be confirmed, as the lead forming the SQUID is sensitive to oxidation and the SQUIDs must be shipped in a vacuum container. After operation of the nanoSQUIDs is confirmed, the primary work of characterizing their high-speed properties will begin. This will include looking at the measurement of relaxation oscillations at high bandwidth in comparison to the theoretical predictions of the current model.

  8. Effect of nano-scale characteristics of graphene on electrochemical performance of activated carbon supercapacitor electrodes

    Science.gov (United States)

    Jasni, M. R. M.; Deraman, M.; Suleman, M.; Hamdan, E.; Sazali, N. E. S.; Nor, N. S. M.; Shamsudin, S. A.

    2016-02-01

    Graphene with its typical nano-scale characteristic properties has been widely used as an additive in activated carbon electrodes in order to enhance the performance of the electrodes for their use in high performance supercapacitors. Activated carbon monoliths (ACMs) electrodes have been prepared by carbonization and activation of green monoliths (GMs) of pre-carbonized fibers of oil palm empty fruit bunches or self-adhesive carbon grains (SACGs) and SACGs added with 6 wt% of KOH-treated multi-layer graphene. ACMs electrodes have been assembled in symmetrical supercapacitor cells that employed aqueous KOH electrolyte (6 M). The cells have been tested with cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge discharge methods to investigate the effect of graphene addition on the specific capacitance (Csp), specific energy (E), specific power (P), equivalent series resistance (ESR) and response time (τo) of the supercapacitor cells. The results show that the addition of graphene in the GMs change the values of Csp, Emax, Pmax, ESR and τo from (61-96) F/g, 2 Wh/kg, 104 W/kg, 2.6 Ω and 38 s, to the respective values of (110-124) F/g, 3 Wh/kg, 156 W/kg, 3.4 Ω and 63 s. This study demonstrates that the graphene addition in the GMs has a significant effect on the electrochemical behavior of the electrodes.

  9. Bilayer lipid membrane (BLM) based ion selective electrodes at the meso-, micro-, and nano-scales.

    Science.gov (United States)

    Liu, Bingwen; Rieck, Daniel; Van Wie, Bernard J; Cheng, Gary J; Moffett, David F; Kidwell, David A

    2009-03-15

    This paper presents a novel method for making micron-sized apertures with tapered sidewalls and nano-sized apertures. Their use in bilayer lipid membrane-based ion selective electrode design is demonstrated and compared to mesoscale bilayers and traditional PVC ion selective electrodes. Micron-sized apertures are fabricated in SU-8 photoresist films and vary in diameter from 10 to 40 microm. The tapered edges in SU-8 films are desired to enhance bilayer lipid membrane (BLM) formation and are fabricated by UV-light overexposure. Nano-apertures are made in boron diffused silicon film. The membranes are used as septa to separate two potassium chloride solutions of different concentrations. Lecithin BLMs are assembled on the apertures by ejecting lipid solution. Potassium ionophore, dibenzo-18-crown-6, is incorporated into BLMs by dissolving it in the lipid solution before membrane assembly. Voltage changes with increasing potassium ion concentrations are recorded with an A/D converter. Various ionophore concentrations in BLMs are investigated. At least a 1% concentration is needed for consistent slopes. Electrode response curves are linear over the 10(-6) to 0.1M range with a sub-Nernstian slope of 20mV per Log concentration change. This system shows high selectivity to potassium ions over potential interfering sodium ions. BLMs on the three different aperture sizes at the meso-, micro-, and nano-scales all show similar linear ranges and limits of detection (LODs) as PVC ion selective membranes.

  10. Euro hybrid materials and structures. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hausmann, Joachim M.; Siebert, Marc (eds.)

    2016-08-01

    In order to use the materials as best as possible, several different materials are usually mixed in one component, especially in the field of lightweight design. If these combinations of materials are joined inherently, they are called multi material design products or hybrid structures. These place special requirements on joining technology, design methods and manufacturing and are challenging in other aspects, too. The eight chapters with manuscripts of the presentations are: Chapter 1- Interface: What happens in the interface between the two materials? Chapter 2 - Corrosion and Residual Stresses: How about galvanic corrosion and thermal residual stresses in the contact zone of different materials? Chapter 3 - Characterization: How to characterize and test hybrid materials? Chapter 4 - Design: What is a suitable design and dimensioning method for hybrid structures? Chapter 5 - Machining and Processing: How to machine and process hybrid structures and materials? Chapter 6 - Component Manufacturing: What is a suitable manufacturing route for hybrid structures? Chapter 7 - Non-Destructive Testing and Quality Assurance: How to assure the quality of material and structures? Chapter 8 - Joining: How to join components of different materials?.

  11. Smart materials-based actuators at the micronano-scale characterization, control, and applications

    CERN Document Server

    2013-01-01

    Smart Materials-Based Actuators at the Micro/Nano-Scale: Characterization, Control, and Applications gives a state of the art of emerging techniques to the characterization and control of actuators based on smart materials working at the micro/nano scale. The book aims to characterize some commonly used structures based on piezoelectric and electroactive polymeric actuators and also focuses on various and emerging techniques employed to control them. This book also includes two of the most emerging topics and applications: nanorobotics and cells micro/nano-manipulation. This book: Provides both theoretical and experimental results Contains complete information from characterization, modeling, identification, control to final applications for researchers and engineers that would like to model, characterize, control and apply their own micro/nano-systems Discusses applications such as microrobotics and their control, design and fabrication of microsystems, microassembly and its automation, nanorobotics and thei...

  12. Toward new fuel cell support materials: a theoretical and experimental study of nitrogen-doped graphene.

    Science.gov (United States)

    Seo, Min Ho; Choi, Sung Mook; Lim, Eun Ja; Kwon, In Hye; Seo, Joon Kyo; Noh, Seung Hyo; Kim, Won Bae; Han, Byungchan

    2014-09-01

    Nano-scale Pt particles are often reported to be more electrochemically active and stable in a fuel cell if properly displaced on support materials; however, the factors that affect their activity and stability are not well understood. We applied first-principles calculations and experimental measurements to well-defined model systems of N-doped graphene supports (N-GNS) to reveal the fundamental mechanisms that control the catalytic properties and structural integrity of nano-scale Pt particles. DFT calculations predict thermodynamic and electrochemical interactions between N-GNS and Pt nanoparticles in the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). Moreover, the dissolution potentials of the Pt nanoparticles supported on GNS and N-GNS catalysts are calculated under acidic conditions. Our results provide insight into the design of new support materials for enhanced catalytic efficiency and long-term stability.

  13. Structure and properties of layered inorganic materials

    Institute of Scientific and Technical Information of China (English)

    Xue Duan

    2010-01-01

    @@ Inorganic layered materials are a class of advanced functional materials that have attracted considerable attention by virtue of their practical applications in a wide variety of fields. Sys-tematic studies of structure, design, synthesis, and fabrication processing may extend the range of practical utility of inor-ganic layered functional materials, in areas such as food industry,chemical industry, energy engineering, environmental engineer-ing, drug and gene delivery, electronics technology, and materials protection.

  14. Magnetism and Structure in Functional Materials

    CERN Document Server

    Planes, Antoni; Saxena, Avadh

    2005-01-01

    Magnetism and Structure in Functional Materials addresses three distinct but related topics: (i) magnetoelastic materials such as magnetic martensites and magnetic shape memory alloys, (ii) the magnetocaloric effect related to magnetostructural transitions, and (iii) colossal magnetoresistance (CMR) and related magnanites. The goal is to identify common underlying principles in these classes of materials that are relevant for optimizing various functionalities. The emergence of apparently different magnetic/structural phenomena in disparate classes of materials clearly points to a need for common concepts in order to achieve a broader understanding of the interplay between magnetism and structure in this general class of new functional materials exhibiting ever more complex microstructure and function. The topic is interdisciplinary in nature and the contributors correspondingly include physicists, materials scientists and engineers. Likewise the book will appeal to scientists from all these areas.

  15. Micromechanics of Damage Accumulation in Micro- and Nano-Scale Laminates for Microelectromechanical Systems

    Science.gov (United States)

    2009-04-06

    Romasco, A.L., “Deformation and Fatigue of Platinum Structural Filims (Invited),” Mini-workshop on MEMS/ NEMS : Characterization and Modeling, Sensor and...Laboratory’s Specialty Electronic Materials and Sensors Cleanroom Facility in Adelphi, MD. Fabrication began with a 100mm diameter single crystal silicon wafer...weakened by the presence of a secondary phase or atomic species 12, “active” (i.e., corrosive ) service environments 13, or gross structural defects such

  16. Biomimetic photonic materials with tunable structural colors.

    Science.gov (United States)

    Xu, Jun; Guo, Zhiguang

    2013-09-15

    Nature is a huge gallery of art involving nearly perfect structures and forms over the millions of years developing. Inspiration from natural structures exhibiting structural colors is first discussed. We give some examples of natural one-, two-, and three-dimensional photonic structures. This review article presents a brief summary of recent progress on bio-inspired photonic materials with variable structural colors, including the different facile and efficient routes to construct the nano-architectures, and the development of the artificial variable structural color photonic materials. Besides the superior optical properties, the excellent functions such as robust mechanical strength, good wettability are also mentioned, as well as the technical importance in various applications. This review will provide significant insight into the fabrication, design and application of the structural color materials.

  17. A nano-scale mirror-like surface of Ti-6Al-4V attained by chemical mechanical polishing

    Science.gov (United States)

    Chenliang, Liang; Weili, Liu; Shasha, Li; Hui, Kong; Zefang, Zhang; Zhitang, Song

    2016-05-01

    Metal Ti and its alloys have been widely utilized in the fields of aviation, medical science, and micro-electro-mechanical systems, for its excellent specific strength, resistance to corrosion, and biological compatibility. As the application of Ti moves to the micro or nano scale, however, traditional methods of planarization have shown their short slabs. Thus, we introduce the method of chemical mechanical polishing (CMP) to provide a new way for the nano-scale planarization method of Ti alloys. We obtain a mirror-like surface, whose flatness is of nano-scale, via the CMP method. We test the basic mechanical behavior of Ti-6Al-4V (Ti64) in the CMP process, and optimize the composition of CMP slurry. Furthermore, the possible reactions that may take place in the CMP process have been studied by electrochemical methods combined with x-ray photoelectron spectroscopy (XPS). An equivalent circuit has been built to interpret the dynamic of oxidation. Finally, a model has been established to explain the synergy of chemical and mechanical effects in the CMP of Ti-6Al-4V. Project supported by the National Major Scientific and Technological Special Project during the Twelfth Five-year Plan Period of China (Grant No. 2009ZX02030-1), the National Natural Science Foundation of China (Grant No. 51205387), the Support by Science and Technology Commission of Shanghai City, China (Grant No. 11nm0500300), and the Science and Technology Commission of Shanghai City, China (Grant No. 14XD1425300).

  18. Synthesis and structural evolution of vanadium carbide in nano scale during mechanical alloying

    Directory of Open Access Journals (Sweden)

    Mohsen Hossein-Zadeh

    2016-07-01

    Full Text Available In this study, nano crystalline vanadium carbide was synthesized by mechanical alloying method. V2O5, C and Mg powders were placed in a planetary ball mill and sampled after different milling times. XRD and FESEM were used for characterization of synthesized powder. Studies showed that crystalline V8C7 has been synthesized by 24 h milling and subsequently heat treatment at 800 °C. It was concluded that the V8C7 crystallites were nano sized and the lattice parameter deviated slightly from the standard size. Furthermore, milling led to increase in strain and decrease of vanadium carbide particle size.

  19. Steels from materials science to structural engineering

    CERN Document Server

    Sha, Wei

    2013-01-01

    Steels and computer-based modelling are fast growing fields in materials science as well as structural engineering, demonstrated by the large amount of recent literature. Steels: From Materials Science to Structural Engineering combines steels research and model development, including the application of modelling techniques in steels.  The latest research includes structural engineering modelling, and novel, prototype alloy steels such as heat-resistant steel, nitride-strengthened ferritic/martensitic steel and low nickel maraging steel.  Researchers studying steels will find the topics vital to their work.  Materials experts will be able to learn about steels used in structural engineering as well as modelling and apply this increasingly important technique in their steel materials research and development. 

  20. Impact of Subsurface Heterogeneities on nano-Scale Zero Valent Iron Transport

    Science.gov (United States)

    Krol, M. M.; Sleep, B. E.; O'Carroll, D. M.

    2011-12-01

    Nano-scale zero valent iron (nZVI) has been applied as a remediation technology at sites contaminated with chlorinated compounds and heavy metals. Although laboratory studies have demonstrated high reactivity for the degradation of target contaminants, the success of nZVI in the field has been limited due to poor subsurface mobility. When injected into the subsurface, nZVI tends to aggregate and be retained by subsurface soils. As such nZVI suspensions need to be stabilized for increased mobility. However, even with stabilization, soil heterogeneities can still lead to non-uniform nZVI transport, resulting in poor distribution and consequently decreased degradation of target compounds. Understanding how nZVI transport can be affected by subsurface heterogeneities can aid in improving the technology. This can be done with the use of a numerical model which can simulate nZVI transport. In this study CompSim, a finite difference groundwater model, is used to simulate the movement of nZVI in a two-dimensional domain. CompSim has been shown in previous studies to accurately predict nZVI movement in the subsurface, and is used in this study to examine the impact of soil heterogeneity on nZVI transport. This work also explores the impact of different viscosities of the injected nZVI suspensions (corresponding to different stabilizing polymers) and injection rates on nZVI mobility. Analysis metrics include travel time, travel distance, and average nZVI concentrations. Improving our understanding of the influence of soil heterogeneity on nZVI transport will lead to improved field scale implementation and, potentially, to more effective remediation of contaminated sites.

  1. Nano-Scale Sample Acquisition Systems for Small Class Exploration Spacecraft

    Science.gov (United States)

    Paulsen, G.

    2015-12-01

    The paradigm for space exploration is changing. Large and expensive missions are very rare and the space community is turning to smaller, lighter, and less expensive missions that could still perform great exploration. These missions are also within reach of commercial companies such as the Google Lunar X Prize teams that develop small scale lunar missions. Recent commercial endeavors such as "Planet Labs inc." and Sky Box Imaging, inc. show that there are new benefits and business models associated with miniaturization of space hardware. The Nano-Scale Sample Acquisition System includes NanoDrill for capture of small rock cores and PlanetVac for capture of surface regolith. These two systems are part of the ongoing effort to develop "Micro Sampling" systems for deployment by the small spacecraft with limited payload capacities. The ideal applications include prospecting missions to the Moon and Asteroids. The MicroDrill is a rotary-percussive coring drill that captures cores 7 mm in diameter and up to 2 cm long. The drill weighs less than 1 kg and can capture a core from a 40 MPa strength rock within a few minutes, with less than 10 Watt power and less than 10 Newton of preload. The PlanetVac is a pneumatic based regolith acquisition system that can capture surface sample in touch-and-go maneuver. These sampling systems were integrated within the footpads of commercial quadcopter for testing. As such, they could also be used by geologists on Earth to explore difficult to get to locations.

  2. Nano-scale islands of ruthenium oxide as an electrochemical sensor for iodate and periodate determination

    Energy Technology Data Exchange (ETDEWEB)

    Chatraei, Fatemeh; Zare, Hamid R., E-mail: hrzare@yazd.ac.ir

    2013-03-01

    In this study, a promising electrochemical sensor was fabricated by the electrodeposition of nano-scale islands of ruthenium oxide (ruthenium oxide nanoparticles, RuON) on a glassy carbon electrode (RuON-GCE). Then, the electrocatalytic oxidation of iodate and periodate was investigated on it, using cyclic voltammetry, chronoamperometry and amperometry as diagnostic techniques. The charge transfer coefficient, {alpha}, and the charge transfer rate constant, k{sub s}, for electron transfer between RuON and GCE were calculated as 0.5 {+-} 0.03 and 9.0 {+-} 0.7 s{sup -1} respectively. A comparison of the data obtained from the electrocatalytic reduction of iodate and periodate at a bare GCE (BGCE) and RuON-GCE clearly shows that the unique electronic properties of nanoparticles definitely improve the characteristics of iodate and periodate electrocatalytic reduction. The kinetic parameters such as the electron transfer coefficient, {alpha}, and the heterogeneous electron transfer rate constant, k Prime , for the reduction of iodate and periodate at RuON-GCE surface were determined using cyclic voltammetry. Amperometry revealed a good linear relationship between the peak current and the concentration of iodate and periodate. The detection limits of 0.9 and 0.2 {mu}M were calculated for iodate and periodate respectively. Highlights: Black-Right-Pointing-Pointer Ruthenium oxide nanoparticles, RuON, were used for electrocatalytic reduction iodate and periodate. Black-Right-Pointing-Pointer Formal potential, E{sup 0} Prime , of the surface redox couple of RuON is pH-dependent. Black-Right-Pointing-Pointer The heterogeneous electron transfer rate constant values between both analytes and RuON were calculated.

  3. Smart materials and structures: what are they?

    Science.gov (United States)

    Spillman, W. B., Jr.; Sirkis, J. S.; Gardiner, P. T.

    1996-06-01

    There has been considerable discussion in the technical community on a number of questions concerned with smart materials and structures, such as what they are, whether smart materials can be considered a subset of smart structures, whether a smart structure and an intelligent structure are the same thing, etc. This discussion is both fueled and confused by the technical community due to the truly multidisciplinary nature of this new field. Smart materials and structures research involves so many technically diverse fields that it is quite common for one field to completely misunderstand the terminology and start of the art in other fields. In order to ascertain whether a consensus is emerging on a number of questions, the technical community was surveyed in a variety of ways including via the internet and by direct contact. The purpose of this survey was to better define the smart materials and structures field, its current status and its potential benefits. Results of the survey are presented and discussed. Finally, a formal definition of the field of smart materials and structures is proposed.

  4. Laser direct writing of micro- and nano-scale medical devices.

    Science.gov (United States)

    Gittard, Shaun D; Narayan, Roger J

    2010-05-01

    Laser-based direct writing of materials has undergone significant development in recent years. The ability to modify a variety of materials at small length scales and using short production times provides laser direct writing with unique capabilities for fabrication of medical devices. In many laser-based rapid prototyping methods, microscale and submicroscale structuring of materials is controlled by computer-generated models. Various laser-based direct write methods, including selective laser sintering/melting, laser machining, matrix-assisted pulsed-laser evaporation direct write, stereolithography and two-photon polymerization, are described. Their use in fabrication of microstructured and nanostructured medical devices is discussed. Laser direct writing may be used for processing a wide variety of advanced medical devices, including patient-specific prostheses, drug delivery devices, biosensors, stents and tissue-engineering scaffolds.

  5. Structural materials for fission & fusion energy

    Directory of Open Access Journals (Sweden)

    Steven J. Zinkle

    2009-11-01

    Full Text Available Structural materials represent the key for containment of nuclear fuel and fission products as well as reliable and thermodynamically efficient production of electrical energy from nuclear reactors. Similarly, high-performance structural materials will be critical for the future success of proposed fusion energy reactors, which will subject the structures to unprecedented fluxes of high-energy neutrons along with intense thermomechanical stresses. Advanced materials can enable improved reactor performance via increased safety margins and design flexibility, in particular by providing increased strength, thermal creep resistance and superior corrosion and neutron radiation damage resistance. In many cases, a key strategy for designing high-performance radiation-resistant materials is based on the introduction of a high, uniform density of nanoscale particles that simultaneously provide good high temperature strength and neutron radiation damage resistance.

  6. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    B S Murty; M K Datta; S K Pabi

    2003-02-01

    Nanocrystalline materials, which are expected to play a key role in the next generation of human civilization, are assembled with nanometre-sized “building blocks” consisting of the crystalline and large volume fractions of intercrystalline components. In order to predict the unique properties of nanocrystalline materials, which are a combination of the properties of the crystalline and intercrystalline regions, it is essential to understand precisely how the structures of crystalline and intercrystalline regions vary with decrease in crystallite size. In addition, study of the thermal stability of nanocrystalline materials against significant grain growth is both scientific and technological interest. A sharp increase in grain size (to micron levels) during consolidation of nanocrystalline powders to obtain fully dense materials may consequently result in the loss of some unique properties of nanocrystalline materials. Therefore, extensive interest has been generated in exploring the size effects on the structure of crystalline and intercrystalline region of nanocrystalline materials, and the thermal stability of nanocrystalline materials against significant grain growth. The present article is aimed at understanding the structure and stability of nanocrystalline materials.

  7. Preparation of Nickel Materials with Fractal Structure

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A way of manufacturing nickel material with fractal structure has been studied. Some algae with natural fractalstructure were used as the basic substrates. The nickel was coated on the substrates by both electroless depositionand electrodeposition. After elimination of the foundational algae by erosion, dissolution etc, the pure nickel materialswith fractal structure were obtained. At last, the specific surface area was analyzed by BET analyses and the fractaldimension of the nickel material was calculated by means of box-counting technique. The comparison of fractaldimension between Ni structure and natural algae was also given.

  8. Freeze Casting for Assembling Bioinspired Structural Materials.

    Science.gov (United States)

    Cheng, Qunfeng; Huang, Chuanjin; Tomsia, Antoni P

    2017-08-23

    Nature is very successful in designing strong and tough, lightweight materials. Examples include seashells, bone, teeth, fish scales, wood, bamboo, silk, and many others. A distinctive feature of all these materials is that their properties are far superior to those of their constituent phases. Many of these natural materials are lamellar or layered in nature. With its "brick and mortar" structure, nacre is an example of a layered material that exhibits extraordinary physical properties. Finding inspiration in living organisms to create bioinspired materials is the subject of intensive research. Several processing techniques have been proposed to design materials mimicking natural materials, such as layer-by-layer deposition, self-assembly, electrophoretic deposition, hydrogel casting, doctor blading, and many others. Freeze casting, also known as ice-templating, is a technique that has received considerable attention in recent years to produce bioinspired bulk materials. Here, recent advances in the freeze-casting technique are reviewed for fabricating lamellar scaffolds by assembling different dimensional building blocks, including nanoparticles, polymer chains, nanofibers, and nanosheets. These lamellar scaffolds are often infiltrated by a second phase, typically a soft polymer matrix, a hard ceramic matrix, or a metal matrix. The unique architecture of the resultant bioinspired structural materials displays excellent mechanical properties. The challenges of the current research in using the freeze-casting technique to create materials large enough to be useful are also discussed, and the technique's promise for fabricating high-performance nacre-inspired structural materials in the future is reviewed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Electronic structure studies of topological materials

    Science.gov (United States)

    Zhou, Shuyun

    Three-dimensional (3D) Dirac fermions are a new class of topological quantum materials. In 3D Dirac semimetals, the conduction and valence bands touch each other at discrete points in the momentum space and show linear dispersions along all momentum directions, forming 3D Dirac cones which are protected by the crystal symmetry. Here I will present our recent studies of the electronic structures of novel materials which host 3D Dirac fermions by using angle-resolved photoemission spectroscopy.

  10. Understanding structural conservation through materials science:

    DEFF Research Database (Denmark)

    Fuster-López, Laura; Krarup Andersen, Cecil

    2014-01-01

    Mechanical properties and the structure of materials are key elements in understanding how structural interventions in conservation treatments affect cultural heritage objects. In this context, engineering mechanics can help determine the strength and stability found in art objects as it can...... with tools to avoid future problems, it should be present in all conservation-restoration training programs to help promote students’ understanding of the degradation mechanisms in cultural materials (and their correlation with chemical and biological degradation) as well as the implications behind...

  11. Electrochemical Characterization of Semiconductor Materials and Structures

    Science.gov (United States)

    1997-01-01

    For a period covering October 1, 1995 through August 12, 1996, the research group at CSU has conducted theoretical and experimental research on "Electrochemical Characterization of Semiconductor Materials and Structures. " The objective of this investigation was to demonstrate the applicability of electrochemical techniques for characterization of complex device structures based on InP and GaAs, Ge, InGaAs, InSb, InAs and InSb, including: (1) accurate EC-V net majority carrier concentration depth profiling, and (2) surface and bulk structural and electrical type defect densities. Our motivation for this R&D effort was as follows: "Advanced space solar cells and ThermoPhotoVoltaic (TPV) cells are fabricated using a large variety of III-V materials based on InP and GaAs for solar cells and low bandgap materials such as Ge, InGaAs, InAs and InSb for TPV applications. At the present time for complex device structures using these materials, however, there is no simple way to assess the quality of these structures prior to device fabrication. Therefore, process optimization is a very time consuming and a costly endeavor". Completion of this R&D effort would have had unquestionable benefits for space solar cell and TPV cells, since electrochemical characterization of the above cell structures, if properly designed can provide many useful structural and electrical material information virtually at any depth inside various layers and at the interfaces. This, could have been applied for step-by-step process optimization, which could have been used for fabrication of new generation high efficiency, low cost space PV and TPV cells.

  12. Nano-Scale Characterization of a Piezoelectric Polymer (Polyvinylidene Difluoride, PVDF

    Directory of Open Access Journals (Sweden)

    Rodrigo Cooper

    2008-11-01

    Full Text Available The polymer polyvinylidene difluoride (PVDF has unique piezoelectric properties favorable for Micro-Electro-Mechanical Systems (MEMS and Nano-Electro-Mechanical Systems (NEMS applications. In the present research, we conducted nanometer-length scale characterization of this material using several high-resolution techniques. Specifically, we used an atomic force microscope (AFM to study the nanoand microstructures of the PVDF under stress and to measure their nanoscale conductivity and piezoelectricity. We found that the surface morphology, electronic structure, and microstructure are profoundly affected under electrical potential. Such a behavior is important for the properties and performance of MEMS and NEMS.

  13. Analysis of Voltage Transfer Characteristics of Nano-scale SOI CMOS Inverter with Variable Channel Length and Doping Concentration

    Directory of Open Access Journals (Sweden)

    A. Daniyel Raj

    2015-03-01

    Full Text Available During many decades, continuous device performance improvement has been made possible only through device scaling. But presently, due to aggressive scaling at the sub-micron or nanometer region, the conventional planner silicon technology is suffering from the fundamental physical limits. Such imposed limits on further downscaling of silicon planner technology have lead to alternative device technology like Silicon-On-Insulator (SOI technology. Due-to some of its inherent advantages, the Silicon-On-Insulator (SOI technology has reduced the Short-channel-effects (SCEs and thus increased transistor scalability. Till now, intense research interests have been paid in practical fabrication and theoretical modeling of SOI MOSFETs but a little attention has been paid to understand the circuit level performance improvement with nano-scale SOI MOSFETs. The circuit level performance analysis of SOI MOSFET is highly essential to understand the impact of SOI technology on next level VLSI circuit and chip design and for doing so device compact models are high on demand. In such scenario, under present research, a physics based compact device model of SOI MOSFET has been developed. At the first phase of the compact model development, a physics based threshold voltage model has been developed by solving 2-D Poisson’s equation at the channel region and at the second phase, a current-voltage model has been developed with drift-diffusion analysis. Different SCEs, valid at nano-scale, are effectively incorporated in threshold voltage and Current-Voltage model. At the third phase, using the compact model, the Voltage Transfer Characteristics (VTC for a nano-scale SOI CMOS inverter has been derived with graphical analysis. The impacts of different device parameters e.g.; channel length and channel doping concentration on VTC has been investigated through simulation and the results have been analyzed.

  14. Preparation of Nano-Scale Biopolymer Extracted from Coconut Residue and Its Performance as Drag Reducing Agent (DRA

    Directory of Open Access Journals (Sweden)

    Hasan Muhammad Luqman Bin

    2017-01-01

    Full Text Available Drag or frictional force is defined as force that acts opposite to the object’s relative motion through a fluid which then will cause frictional pressure loss in the pipeline. Drag Reducing Agent (DRA is used to solve this issue and most of the DRAs are synthetic polymers but has some environmental issues. Therefore for this study, biopolymer known as Coconut Residue (CR is selected as the candidate to replace synthetic polymers DRA. The objective of this study is to evaluate the effectiveness of Nano-scale biopolymer DRA on the application of water injection system. Carboxymethyl cellulose (CMC is extracted by synthesizing the cellulose extracted from CR under the alkali-catalyzed reaction using monochloroacetic acid. The synthesize process is held in controlled condition whereby the concentration of NaOH is kept at 60%wt, 60 °C temperature and the reaction time is 4 hours. For every 25 g of dried CR used, the mass of synthesized CMC yield is at an average of 23.8 g. The synthesized CMC is then grinded in controlled parameters using the ball milling machine to get the Nano-scale size. The particle size obtained from this is 43.32 Nm which is in range of Nano size. This study proved that Nano-size CMC has higher percentage of drag reduction (%DR and flow increase (%FI if compared to normal-size CMC when tested in high and low flow rate; 44% to 48% increase in %DR and %FI when tested in low flow rate, and 16% to 18% increase in %DR and %FI when tested in high flow rate. The success of this research shows that Nano-scale DRA can be considered to be used to have better performance in reducing drag.

  15. Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    Science.gov (United States)

    Zhamu, Aruna; Jang, Bor Z.

    2014-06-17

    A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

  16. Study on thin film lubrication in the nano scale%纳米薄膜润滑研究

    Institute of Scientific and Technical Information of China (English)

    温诗铸; 雒建斌

    2001-01-01

    该文是近年来作者关于纳米薄膜润滑的研究的全面总结。首先介绍了纳米量级润滑膜厚度测量技术,进而系统地阐述了润滑理论中存在的两个尚未完全弄清的问题,即弹流润滑和边界润滑之间润滑状态的形态特征以及润滑膜的失效准则,包括:1)薄膜润滑作为弹流润滑与边界润滑之间一种新的润滑状态的性能特征;2)薄膜润滑的物理模型,弹流润滑与薄膜润滑间的转化关系以及膜厚与工况因子的相关性;3)纳米润滑膜时间效应及其产生原因;4)电场对纳米润滑膜特性的影响;5)纳米润滑膜的失效准则;6)新的润滑状态判断准则。%he summary of recent research about thin film lubrication (TFL)in the nano scale is made. First, the measuring technique of film thickness in the nano scale is introduced. Then, the two problems unsettled completely in lubrication theory, such as the characteristics of the lubrication regime between elasto- hydrodynamic lubrication (EHL) and boundary lubrication (BL), and the failure criterion of the lubricant film, are expounded systematically. They include: 1) the characteristics of TFL as a new lubrication regime between EHL and BL, 2) physical model of TFL, transition conditions from EHL to TFL and the relationship between the film thickness and operating parameters, 3) the time effect of lubricating film in the nano scale and the reason of its creation, 4) the effect of external electric field on the nanotribological properties of lubricant film, 5) the failure criterion of lubricant film in the nano scale, 6) a new method distinguishing lubrication regimes.

  17. Theory, synthesis and characterization of nano-scale architectures for solid-state hydrogen storage

    Science.gov (United States)

    Miller, Michael A.

    Traditional materials discovery and development techniques have not yet yielded the necessary breakthroughs needed for practical utilization of hydrogen storage. An integrated theoretical-experimental approach to the development of novel materials capable of hydrogen storage under the narrow thermodynamic regime suitable for automotive applications is undertaken. The viability of engineering two-part nano-architectures (heterostructures) to enhance the binding energy between molecular hydrogen and solid-state nanostructures, or to evince dissociation and uptake of hydrogen into the architecture, was explored. First, exceptional hydrogen uptake (7.5 wt.%) was validated in a metal organic framework compound, MOF-177, at low temperature (77 K), and a thermodynamic model for physisorption was established as a benchmark for all such structures. A chemisorptive pathway for enhanced hydrogen uptake (2.2 wt.%) at room temperature in heterostructures of metal-organic-frameworks (MOFs), via a mechanism now referred to as hydrogen spillover, was experimentally validated and further studied through computations. Ab initio computations at the level of Hartree-Fock (HF) and density functional theories (DFT) made it possible to calculate the thermochemical properties of hydrogen uptake in Pt-doped MOF heterostructures, which verified the thermodynamic plausibility of hydrogen spillover. Furthermore, the hydrogen spillover mechanism was successfully elicited from heterostructures consisting of metal-doped carbon materials, which yielded the highest uptake of hydrogen ever measured at room temperature (8.0 wt.%) for carbon-based material. The theoretical foundation was formed for a new way of considering how binding interactions between small molecules, such as dihydrogen, and an engineered surface may be influenced by coupling molecular vibrations with low-frequency surface plasmons in clusters of a metal compound. Finally, new MOF-based heterostructures in which a metal dopant is

  18. Structural engineering, mechanics and materials: Final report

    Energy Technology Data Exchange (ETDEWEB)

    1988-01-01

    This report on structural engineering, mechanics and materials is divided into three parts: a discussion on using Lanczos vectors and Ritz vectors for computing dynamic responses: solution of viscously damped linear systems using a finite element displacement formulation; and vibration analysis of fluid-solid systems using a finite element displacement formulation. (JF)

  19. Failure Analysis of Composite Structure Materials.

    Science.gov (United States)

    1986-05-01

    8MATERIAL STRUCTURES DISCONTINUITY T•R PLY DROPOFF i 7ARC LAP/GAP . PRPAATION A, ,OM LY , 1e, ’ •INS ERVICE MAINTENANCE DAMAGE SVv , S IMPACT \\\\ CHESIE ...composite joints such as box beam members, for example, are difficult to inspect by ultrasonic techniques, and the X-ray attenuation coefficients of

  20. Life of structures of composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Koznetsov, N.D.; Stepanenko, N.D.

    1986-06-01

    The introduction of composite materials in gas turbine engines is rationally done in stages. It is desirable to concentrate efforts on the use of them for production of vanes, sound deadening panes, the reverse rod, and other elements of the stator. The authors use compressor blades as an example of the basic principles of design, the selection of the reinforcing structure, and inspection of the quality of structures of composite materials. A method of determination of the elastodamping properties of polymer composite materials on specimens with free ends in high frequency flexural vibrations excited by a modulated jet of compressed air has been developed and standardized. With the use of this method such defects as separations, cracks, disorientation of the reinforcing, deviations in the order of alternation and the angular orientation of the layers are revealed.

  1. Influence of gradual cobalt substitution on lithium nickel phosphate nano-scale composites for high voltage applications

    Energy Technology Data Exchange (ETDEWEB)

    Örnek, Ahmet, E-mail: ahmetornek0302@hotmail.com [Kafkas University, Atatürk Vocational School of Healthcare, 36100 Kars (Turkey); Bulut, Emrah [Sakarya University, Department of Chemistry, 54187 Sakarya (Turkey); Can, Mustafa [Sakarya University, Arifiye Vocational School, 54580 Sakarya (Turkey)

    2015-08-15

    The carbon-free LiNiPO{sub 4} and cobalt doped LiNi{sub 1−x}Co{sub x}PO{sub 4}/C (x = 0.0–1.0) were synthesized and investigated for high voltage applications (> 4 V) for Li-ion batteries. Nano-scale composites were prepared by handy sol–gel approach using citric acid under slightly reductive gas atmosphere (Ar-H{sub 2}, 85:15%). Structural and morphological characteristics of the powders were revealed by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and inductively coupled plasma (ICP). Except for a small impurity phase (Ni{sub 3}P), phase pure samples crystallized in the olivine-lattice structure with a linear relationship between lattice parameters (a, b and c) and chemical composition. The FE-SEM images proved that LiNiPO{sub 4}/C particles (50–80 nm) did not agglomerate, and showed that as the cobalt content was higher agglomeration had increased. The electrochemical properties of all electrodes were investigated by galvanostatic charge–discharge measurements. Substitution of Ni{sup 2} {sup +} by Co{sup 2} {sup +} caused higher electronic conductivities and showed more effective Li{sup +} ion mobility. When the cobalt content is 100%, the capacity reached to a higher level (146.2 mA h g{sup −} {sup 1}) and good capacity retention of 85.1% at the end of the 60 cycles was observed. The cycling voltammogram (CV) revealed that LiCoPO{sub 4}/C electrode improved the electrochemical properties. The Ni{sup 3} {sup +}–Ni{sup 2} {sup +} redox couple was not observed for carbon free LiNiPO{sub 4}. Nevertheless, it was observed that carbon coated LiNiPO{sub 4} sample exhibits a significant oxidation (5.26 V)–reduction (5.08 V) peaks. With this study, characteristics of the LiNi{sub 1−x}Co{sub x}PO{sub 4}/C series were deeply evaluated and discussed. - Highlights: • Structural, morphological and electrochemical effects of Co doped LiNi{sub 1−} {sub x

  2. Ordered mesoporous silica materials with complicated structures

    KAUST Repository

    Han, Yu

    2012-05-01

    Periodically ordered mesoporous silicas constitute one of the most important branches of porous materials that are extensively employed in various chemical engineering applications including adsorption, separation and catalysis. This short review gives an introduction to recently developed mesoporous silicas with emphasis on their complicated structures and synthesis mechanisms. In addition, two powerful techniques for solving complex mesoporous structures, electron crystallography and electron tomography, are compared to elucidate their respective strength and limitations. Some critical issues and challenges regarding the development of novel mesoporous structures as well as their applications are also discussed. © 2011 Elsevier Ltd.

  3. Focus issue introduction: synergy of structured light and structured materials.

    Science.gov (United States)

    Omatsu, Takashige; Litchinitser, Natalia M; Brasselet, Etienne; Morita, Ryuji; Wang, Jian

    2017-07-10

    Structured light beams, such as optical vortices, vector beams, and non-diffracting beams, have been recently studied in a variety of fields, such as optical manipulations, optical telecommunications, nonlinear interactions, quantum physics, and 'super resolution' microscopy.. Their unique physical properties, such as annular intensity profile, helical wavefront and orbital angular momentum, give rise to a plethora of new, fundamental light-matter interactions and device applications. Recent progress in nanostructured materials, including metamaterials and metasurfaces, opened new opportunities for structured light generation on the microscale that exceed the capabilities of bulk-optics approaches such as computer generated holography and diffractive optics. Furthermore, structured optical fields may interact with matters on the subwavelength scale to yield new physical effects, such as spin-orbital momentum coupling. This special issue of Optics Express focuses on the state-of-the-art fundamental research and emerging technologies and applications enabled by the interplay of "structured light" and "structured materials".

  4. Determination of crystal growth rates during rapid solidification of polycrystalline aluminum by nano-scale spatio-temporal resolution in situ transmission electron microscopy

    Science.gov (United States)

    Zweiacker, K.; McKeown, J. T.; Liu, C.; LaGrange, T.; Reed, B. W.; Campbell, G. H.; Wiezorek, J. M. K.

    2016-08-01

    In situ investigations of rapid solidification in polycrystalline Al thin films were conducted using nano-scale spatio-temporal resolution dynamic transmission electron microscopy. Differences in crystal growth rates and asymmetries in melt pool development were observed as the heat extraction geometry was varied by controlling the proximity of the laser-pulse irradiation and the associated induced melt pools to the edge of the transmission electron microscopy support grid, which acts as a large heat sink. Experimental parameters have been established to maximize the reproducibility of the material response to the laser-pulse-related heating and to ensure that observations of the dynamical behavior of the metal are free from artifacts, leading to accurate interpretations and quantifiable measurements with improved precision. Interface migration rate measurements revealed solidification velocities that increased consistently from ˜1.3 m s-1 to ˜2.5 m s-1 during the rapid solidification process of the Al thin films. Under the influence of an additional large heat sink, increased crystal growth rates as high as 3.3 m s-1 have been measured. The in situ experiments also provided evidence for development of a partially melted, two-phase region prior to the onset of rapid solidification facilitated crystal growth. Using the experimental observations and associated measurements as benchmarks, finite-element modeling based calculations of the melt pool evolution after pulsed laser irradiation have been performed to obtain estimates of the temperature evolution in the thin films.

  5. Performance assessment and optimization of an irreversible nano-scale Stirling engine cycle operating with Maxwell-Boltzmann gas

    Science.gov (United States)

    Ahmadi, Mohammad H.; Ahmadi, Mohammad-Ali; Pourfayaz, Fathollah

    2015-09-01

    Developing new technologies like nano-technology improves the performance of the energy industries. Consequently, emerging new groups of thermal cycles in nano-scale can revolutionize the energy systems' future. This paper presents a thermo-dynamical study of a nano-scale irreversible Stirling engine cycle with the aim of optimizing the performance of the Stirling engine cycle. In the Stirling engine cycle the working fluid is an Ideal Maxwell-Boltzmann gas. Moreover, two different strategies are proposed for a multi-objective optimization issue, and the outcomes of each strategy are evaluated separately. The first strategy is proposed to maximize the ecological coefficient of performance (ECOP), the dimensionless ecological function (ecf) and the dimensionless thermo-economic objective function ( F . Furthermore, the second strategy is suggested to maximize the thermal efficiency ( η), the dimensionless ecological function (ecf) and the dimensionless thermo-economic objective function ( F). All the strategies in the present work are executed via a multi-objective evolutionary algorithms based on NSGA∥ method. Finally, to achieve the final answer in each strategy, three well-known decision makers are executed. Lastly, deviations of the outcomes gained in each strategy and each decision maker are evaluated separately.

  6. Rheology, microrheology and structure of soft materials

    Science.gov (United States)

    Oppong, Felix K.

    We study the relationship between the bulk rheological properties and the micron-scale structure and rheology of different types of soft materials. The materials studied are Laponite, a colloidal clay suspension; Carbopol, a dispersion of microgel particles; hydroxyethyl cellulose, a linear polymer solution; and hydrophobically modified hydroxyethyl cellulose, an associative polymer. Bulk properties are measured using conventional shear rheometry. The micron-scale measurements are performed using techniques based on multiple particle tracking and dynamic light scattering. From the thermal motion of suspended tracer particles, we obtain information about the local structure and viscoelastic properties of the materials. We investigate the evolution of Laponite from a liquid to a gel and find that the process is length-scale dependent. We study the properties of Carbopol as a function of microgel concentration and find that as concentration increases, a jamming transition occurs which is related to the onset of yield stress on the bulk scale. We compare the viscoelastic properties of hydroxyethylcellulose and its associative derivative and observe that the hydrophobic interactions in the latter lead to much slower dynamics than in the unmodified polymer. A study of the stress relaxation in hydroxyethylcellulose showed that it depended on both the wait time after the application and removal of a large strain and on the type and magnitude of the deformation applied. Our work exploits the unique ability of microrheological techniques to probe both the rheology and structure of soft materials on the microscopic scale, which enables a better understanding of the relationship between bulk scale properties and microscopic structure in these systems. Keywords. Rheology, microrheology, soft materials, particle tracking, dynamic light scattering, viscoelasticity, yield stress, gelation, polymers.

  7. Structural materials challenges for advanced reactor systems

    Science.gov (United States)

    Yvon, P.; Carré, F.

    2009-03-01

    Key technologies for advanced nuclear systems encompass high temperature structural materials, fast neutron resistant core materials, and specific reactor and power conversion technologies (intermediate heat exchanger, turbo-machinery, high temperature electrolytic or thermo-chemical water splitting processes, etc.). The main requirements for the materials to be used in these reactor systems are dimensional stability under irradiation, whether under stress (irradiation creep or relaxation) or without stress (swelling, growth), an acceptable evolution under ageing of the mechanical properties (tensile strength, ductility, creep resistance, fracture toughness, resilience) and a good behavior in corrosive environments (reactor coolant or process fluid). Other criteria for the materials are their cost to fabricate and to assemble, and their composition could be optimized in order for instance to present low-activation (or rapid desactivation) features which facilitate maintenance and disposal. These requirements have to be met under normal operating conditions, as well as in incidental and accidental conditions. These challenging requirements imply that in most cases, the use of conventional nuclear materials is excluded, even after optimization and a new range of materials has to be developed and qualified for nuclear use. This paper gives a brief overview of various materials that are essential to establish advanced systems feasibility and performance for in pile and out of pile applications, such as ferritic/martensitic steels (9-12% Cr), nickel based alloys (Haynes 230, Inconel 617, etc.), oxide dispersion strengthened ferritic/martensitic steels, and ceramics (SiC, TiC, etc.). This article gives also an insight into the various natures of R&D needed on advanced materials, including fundamental research to investigate basic physical and chemical phenomena occurring in normal and accidental operating conditions, lab-scale tests to characterize candidate materials

  8. Materials and structures under shock and impact

    CERN Document Server

    Bailly, Patrice

    2013-01-01

    In risk studies, engineers often have to consider the consequences of an accident leading to a shock on a construction. This can concern the impact of a ground vehicle or aircraft, or the effects of an explosion on an industrial site.This book presents a didactic approach starting with the theoretical elements of the mechanics of materials and structures, in order to develop their applications in the cases of shocks and impacts. The latter are studied on a local scale at first. They lead to stresses and strains in the form of waves propagating through the material, this movement then extending

  9. Application of smart materials in automotive structures

    Science.gov (United States)

    Manz, Holger; Breitbach, Elmar J.

    2001-06-01

    The demand in the automobile sector for greater comfort in the vehicle is of a high importance alongside the requirements for a low emission of pollutants. With regard to a higher comfort the reduction of the interior noise level is mostly associated with a higher structural weight. It is for this reason that the application of so-called intelligent materials is appropriate since these can be used to realize an overall adaptive system. The materials under discussion are pizeceramic foils and fibers which can easily be fitted to thin-walled structures like a roof panel or a dash-board. Investigations have shown that the knowledge of the dynamic structural behavior is vital at the design of an adaptive system. Mostly this knowledge can only be gained by using sophisticated numerical models associated with a great effort of computing time. In order not to expand the computing time a model has been developed which allows a fast assessment of the dynamic behavior of a structure with integrated smart materials. The results of this model are presented for a flat steel plate with bonded piezoceramic foils. The accuracy of this model is being proved by the presentation of experimental results.

  10. Coherent Fe-rich nano-scale perovskite oxide phase in epitaxial Sr2FeMoO6 films grown on cubic and scandate substrates

    Science.gov (United States)

    Deniz, Hakan; Preziosi, Daniele; Alexe, Marin; Hesse, Dietrich

    2017-01-01

    We report the growth of high-quality epitaxial Sr2FeMoO6 (SFMO) thin films on various unconventional oxide substrates, such as TbScO3, DyScO3, and Sr2Al0.3Ga0.7TaO6 (SAGT) as well as on the most commonly used one, SrTiO3 (STO), by pulsed laser deposition. The films were found to contain a foreign nano-scale phase coherently embedded inside the SFMO film matrix. Through energy dispersive X-ray spectroscopy and scanning transmission electron microscopy, we identified the foreign phase to be Sr2-xFe1+yMo1-yO6, an off-stoichiometric derivative of the SFMO compound with Fe rich content (y ≈ 0.6) and a fairly identical crystal structure to SFMO. The films on STO and SAGT exhibited very good magnetic properties with high Curie temperature values. All the samples have fairly good conducting behavior albeit the presence of a foreign phase. Despite the relatively large number of items of the foreign phase, there is no significant deterioration in the properties of the SFMO films. We discuss in detail how magneto-transport properties are affected by the foreign phase.

  11. Scientific Challenges of Producing Natural Gas from Organic-Rich Shales - From the Nano-Scale to the Reservoir Scale (Louis Néel Medal Lecture)

    Science.gov (United States)

    Zoback, Mark D.

    2013-04-01

    In this talk I will discuss several on-going research projects with the PhD students and post-Docs in my group that are investigating the wide variety of factors affecting the success of stimulating gas production from extremely low permeability organic-rich shales. First, I will present laboratory measurements of pore structure, adsorption and nano-scale fluid transport on samples of the Barnett, Eagle Ford, Haynesville, Marcellus and Horn River shale (all in North America). I will also discuss how these factors affect ultimate gas recovery. Second, I present several lines of evidence that indicate that during hydraulic fracturing stimulation of shale gas reservoirs there is pervasive slow slip occurring on pre-existing fractures and faults that are not detected by standard microseismic monitoring. I will also present laboratory and modeling studies that demonstrate why slowly slipping faults are to be expected. In many cases, slow slip on faults may be the most important process responsible for stimulating gas production in the reservoirs. Finally, I discuss our research on the viscoplastic behavior of the shales and what viscoplasticity implies for the evolution of the physical properties of the reservoir and in situ stress magnitudes.

  12. On Structure and Properties of Amorphous Materials

    Directory of Open Access Journals (Sweden)

    Zbigniew H. Stachurski

    2011-09-01

    Full Text Available Mechanical, optical, magnetic and electronic properties of amorphous materials hold great promise towards current and emergent technologies. We distinguish at least four categories of amorphous (glassy materials: (i metallic; (ii thin films; (iii organic and inorganic thermoplastics; and (iv amorphous permanent networks. Some fundamental questions about the atomic arrangements remain unresolved. This paper focuses on the models of atomic arrangements in amorphous materials. The earliest ideas of Bernal on the structure of liquids were followed by experiments and computer models for the packing of spheres. Modern approach is to carry out computer simulations with prediction that can be tested by experiments. A geometrical concept of an ideal amorphous solid is presented as a novel contribution to the understanding of atomic arrangements in amorphous solids.

  13. Nondestructive Testing of Materials and Structures

    CERN Document Server

    Akkaya, Yılmaz

    2013-01-01

    Condition assessment and characterization of materials and structures by means of nondestructive testing (NDT) methods is a priority need around the world to meet the challenges associated with the durability, maintenance, rehabilitation, retrofitting, renewal and health monitoring of new and existing infrastructures including historic monuments. Numerous NDT methods that make use of certain components of the electromagnetic and acoustic spectra are currently in use to this effect with various levels of success and there is an intensive worldwide research effort aimed at improving the existing methods and developing new ones. The knowledge and information compiled in this book captures the current state-of-the-art in NDT methods and their application to civil and other engineering materials and structures. Critical reviews and advanced interdisciplinary discussions by world-renowned researchers point to the capabilities and limitations of the currently used NDT methods and shed light on current and future res...

  14. Electronic structure and magnetism of complex materials

    CERN Document Server

    Papaconstantopoulos, D A

    2003-01-01

    Recent developments in electronic structure theory have led to a new understanding of magnetic materials at the microscopic level. This enables a truly first-principles approach to investigations of technologically important magnetic materials. Among these advances have been practical schemes for handling non-collinear magnetic systems, including relativity, understanding of the origins and role of orbital magnetism within band structure formalisms, density functional approaches for magnons and low-lying spin excitations, understanding of the interplay of orbital, spin and lattice orderings in complex oxides, transport theories for layered systems, and the theory of magnetic interactions in doped semiconductors. The book covers these recent developments with review articles by some of the main originators of these advances.

  15. Structure of grain boundaries in hexagonal materials

    CERN Document Server

    Sarrazit, F

    1998-01-01

    which allows the behaviour of line-defects to be studied in complex interfacial processes. The work presented in this thesis describes experimental and theoretical aspects associated with the structure of grain boundaries in hexagonal materials. It has been found useful to classify grain boundaries as low-angle, special or general on the basis of their structure. High-angle grain boundaries were investigated in tungsten carbide (WC) using conventional electron microscopy techniques, and three examples characteristic of the interfaces observed in this material were studied extensively. Three-dimensionally periodic patterns are proposed as plausible reference configurations, and the Burgers vectors of observed interfacial dislocations were predicted using a theory developed recently. The comparison of experimental observations with theoretical predictions proved to be difficult as contrast simulation techniques require further development for analysis to be completed confidently. Another part of this work invol...

  16. Organic photosensitive cells grown on rough electrode with nano-scale morphology control

    Science.gov (United States)

    Yang, Fan; Forrest, Stephen R.

    2011-06-07

    An optoelectronic device and a method for fabricating the optoelectronic device includes a first electrode disposed on a substrate, an exposed surface of the first electrode having a root mean square roughness of at least 30 nm and a height variation of at least 200 nm, the first electrode being transparent. A conformal layer of a first organic semiconductor material is deposited onto the first electrode by organic vapor phase deposition, the first organic semiconductor material being a small molecule material. A layer of a second organic semiconductor material is deposited over the conformal layer. At least some of the layer of the second organic semiconductor material directly contacts the conformal layer. A second electrode is deposited over the layer of the second organic semiconductor material. The first organic semiconductor material is of a donor-type or an acceptor-type relative to the second organic semiconductor material, which is of the other material type.

  17. Micro/nano-scale investigation on tin alloys and tin dioxide nanowires

    Science.gov (United States)

    Sun, Yong

    Tin (Sn) and its alloys have been at people's service since 3000 BC when bronze (alloy of tin and copper) was produced in large scale. They have unique properties and find applications in various engineering fields. Correspondingly, there is abundant information waiting to be clarified surrounding these Sn-related materials. As the key element used for solder alloys, the properties of Sn alloys have been of great interest to the electronic packaging community. At the same time, the intriguing phenomenon of spontaneous Sn whisker growth from Sn / Sn-alloy thin films have bothered, yet also inspired materials scientists for over 60 years. The most commonly seen Sn-containing compound, SnO 2, is in high demand as well due to its exceptional electronic and chemical properties. In addition, nanostructures of SnO2 are intensively studied for their potential applications as solid-state sensors, transparent conducting materials, lithium-ion batteries, high-efficiency solar cell and recently, supercapacitors. The objective of this proposed research is to explore the amazing properties of Sn and Sn-alloys from several different perspectives. Firstly, ever since the banish of lead in solder alloys, lead-free alloys such as Sn-Ag-Cu (SAC) has been put under the spotlight. We intend to use our expertise in nanomechanics to give an in-depth and thorough investigation on a popular SAC387 alloy. The mechanical properties of each phase and the local deformation mechanisms have been considered. Secondly, the Sn whisker growth phenomenon is to be re-visited. With the aid of digital image correlation (DIC) techniques, it was found that magnitude of the strain gradient plays an important role in whisker growth. Moreover, DIC helps to visualize the dynamic growth process in which the alteration of strain field has been identified to cause growth of subsequent whiskers. Last but not least, the performance of SnO2 nanowires is to be evaluated in several aspects including mechanical

  18. Nonlinear Dynamics of Structures with Material Degradation

    Science.gov (United States)

    Soltani, P.; Wagg, D. J.; Pinna, C.; Whear, R.; Briody, C.

    2016-09-01

    Structures usually experience deterioration during their working life. Oxidation, corrosion, UV exposure, and thermo-mechanical fatigue are some of the most well-known mechanisms that cause degradation. The phenomenon gradually changes structural properties and dynamic behaviour over their lifetime, and can be more problematic and challenging in the presence of nonlinearity. In this paper, we study how the dynamic behaviour of a nonlinear system changes as the thermal environment causes certain parameters to vary. To this end, a nonlinear lumped mass modal model is considered and defined under harmonic external force. Temperature dependent material functions, formulated from empirical test data, are added into the model. Using these functions, bifurcation parameters are defined and the corresponding nonlinear responses are observed by numerical continuation. A comparison between the results gives a preliminary insight into how temperature induced properties affects the dynamic response and highlights changes in stability conditions of the structure.

  19. Novel Engineered Refractory Materials for Advanced Reactor Applications

    Energy Technology Data Exchange (ETDEWEB)

    Shannon, Steven [North Carolina State Univ., Raleigh, NC (United States); Eapen, Jacob [North Carolina State Univ., Raleigh, NC (United States); Maria, Jon-Paul [North Carolina State Univ., Raleigh, NC (United States); Weber, William [Univ. of Tennessee, Knoxville, TN (United States)

    2016-03-14

    This report summarizes the results of DOE-NEUP grant 10-853. The project spanned 48 months (36 months under the original grant plus a 12 month no cost extension). The overarching goal of this work was to fabricate and characterize refractory materials engineered at the atomic scale with emphasis on their tolerance to accumulated radiation damage. With an emphasis on nano-scale structure, this work included atomic scale simulation to study the underlying mechanisms for modified radiation tolerance at these atomic scales.

  20. Non-linear optics of nano-scale pentacene thin film

    Science.gov (United States)

    Yahia, I. S.; Alfaify, S.; Jilani, Asim; Abdel-wahab, M. Sh.; Al-Ghamdi, Attieh A.; Abutalib, M. M.; Al-Bassam, A.; El-Naggar, A. M.

    2016-07-01

    We have found the new ways to investigate the linear/non-linear optical properties of nanostructure pentacene thin film deposited by thermal evaporation technique. Pentacene is the key material in organic semiconductor technology. The existence of nano-structured thin film was confirmed by atomic force microscopy and X-ray diffraction. The wavelength-dependent transmittance and reflectance were calculated to observe the optical behavior of the pentacene thin film. It has been observed the anomalous dispersion at wavelength λ 800. The non-linear refractive index of the deposited films was investigated. The linear optical susceptibility of pentacene thin film was calculated, and we observed the non-linear optical susceptibility of pentacene thin film at about 6 × 10-13 esu. The advantage of this work is to use of spectroscopic method to calculate the liner and non-liner optical response of pentacene thin films rather than expensive Z-scan. The calculated optical behavior of the pentacene thin films could be used in the organic thin films base advanced optoelectronic devices such as telecommunications devices.

  1. Electronic Structure of Strongly Correlated Materials

    CERN Document Server

    Anisimov, Vladimir

    2010-01-01

    Electronic structure and physical properties of strongly correlated materials containing elements with partially filled 3d, 4d, 4f and 5f electronic shells is analyzed by Dynamical Mean-Field Theory (DMFT). DMFT is the most universal and effective tool used for the theoretical investigation of electronic states with strong correlation effects. In the present book the basics of the method are given and its application to various material classes is shown. The book is aimed at a broad readership: theoretical physicists and experimentalists studying strongly correlated systems. It also serves as a handbook for students and all those who want to be acquainted with fast developing filed of condensed matter physics.

  2. On Optimal Shapes in Materials and Structures

    DEFF Research Database (Denmark)

    Pedersen, Pauli

    2000-01-01

    In the micromechanics design of materials, as well as in the design of structural connections, the boundary shape plays an important role. The objective may be the stiffest design, the strongest design or just a design of uniform energy density along the shape. In an energy formulation it is proven...... that these three objectives have the same solution, at least within the limits of geometrical constraints, including the parametrization. Without involving stress/strain fields, the proof holds for 3D-problems, for power-law nonlinear elasticity and for anisotropic elasticity. To clarify the importance...... of parametrization, the problem of material/hole design for maximum bulk modulus is analysed. A simple optimality criterion is derived and with a simple superelliptic parametrization, agreement with Hashin-Shtrikman bounds are found. More general examples including nonequal principal strains, nonlinear elasticity...

  3. Ageing in civil engineering materials and structures

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, Jean-Marc [SETEC TPI, Tour Gamma D 58, quai de la Rapee, 75583 Paris (France)

    2005-07-01

    SETEC TPI will address the 'Aging' topic of the Dijon Symposium by talking about: aging in civil engineering materials and structures, prevention of aging phenomena, in-operation monitoring of degradations related to aging and compensatory measures required to maintain a good safety level. Works as the Millau viaduct, the EdF skyscraper at La Defense - Paris, the renovation of the Grand Palais of Paris and special structures with Monaco's floating dam as well as the 'number 10' shaped gateway boat at Marseilles are illustrations for the issues discussed. The durability of civil engineering structures has become a major concern for designers. The Millau viaduct is designed for a service life of 120 years, and the Monaco dam for 100 years. Calculation rules have been evolving toward the incorporation of the concept of life cycle, for example, the Eurocodes 2 rules (reinforced concrete). The talk will expose the factors which are being taken into account to delay aging versus structure types. This part will be focused towards materials and corresponding regulations: - Reinforced concrete (coating of reinforcements, opening of cracks, choice of reinforcement types), BAEL and Eurocodes 2 rules; - Frame steel (protection, sacrificial anode), CM66 and Eurocodes 3 rules. New materials will also be mentioned: - Ultra high-performance fiber/concrete, with the example of CERACEM applied at Millau for the covering of the toll area barrier; - Titanium, which is starting to appear in the building trades, as for instance for the Beijing China Opera House shell. The second part of the talk will be devoted to a specific case namely, the 'number 10' shaped gateway bridge, a prestressed concrete structure immersed in the Port of Marseilles, which will be used to illustrate the aging phenomenon in a corrosive environment. We will focus on the types of inspection series performed by the Autonomous Port Authority of Marseilles to check the behavior of

  4. Entransy analysis and optimization of performance of nano-scale irreversible Otto cycle operating with Maxwell-Boltzmann ideal gas

    Science.gov (United States)

    Ahmadi, Mohammad H.; Ahmadi, Mohammad Ali; Pourfayaz, Fathollah; Bidi, Mokhtar

    2016-08-01

    This paper made attempt to investigate thermodynamically a nano scale irreversible Otto cycle for optimizing its performance. This system employed an ideal Maxwell-Boltzmann gas as a working fluid. Two different scenarios were proposed in the multi-objective optimization process and the results of each of the scenarios were examined separately. The first scenario made attempt to maximize the dimensionless ecological function and minimize the dimensionless entransy dissipation of the system. Furthermore, the second scenario tried to maximize the ecological coefficient of performance and minimize the dimensionless entransy dissipation of the system. The multi objective evolutionary method integrated with non-dominated sorting genetic algorithm was used to optimize the proposed objective functions. To determine the final output of each scenario, three efficient decision makers were employed. Finally, error analysis was employed to determine the deviation of solutions chosen by decision makers.

  5. Signal Processing for Wireless Communication MIMO System with Nano- Scaled CSDG MOSFET based DP4T RF Switch.

    Science.gov (United States)

    Srivastava, Viranjay M

    2015-01-01

    In the present technological expansion, the radio frequency integrated circuits in the wireless communication technologies became useful because of the replacement of increasing number of functions, traditional hardware components by modern digital signal processing. The carrier frequencies used for communication systems, now a day, shifted toward the microwave regime. The signal processing for the multiple inputs multiple output wireless communication system using the Metal- Oxide-Semiconductor Field-Effect-Transistor (MOSFET) has been done a lot. In this research the signal processing with help of nano-scaled Cylindrical Surrounding Double Gate (CSDG) MOSFET by means of Double- Pole Four-Throw Radio-Frequency (DP4T RF) switch, in terms of Insertion loss, Isolation, Reverse isolation and Inter modulation have been analyzed. In addition to this a channel model has been presented. Here, we also discussed some patents relevant to the topic.

  6. Optical waveguide materials, structures, and dispersion modulation

    Science.gov (United States)

    Zhang, Hao; Liu, Jiaming; Lin, Jian; Li, Wenxiu; Xue, Xia; Huang, Anping; Xiao, Zhisong

    2016-11-01

    Optical waveguide is used in most integrated optic devices to confine and guide light in higher refractive index channels. The structures and materials of slot waveguides are reviewed in this paper. Coupled resonator optical waveguides (CROWs) can be used for a rotation sensor with compact size, low power consumption and low cost. The loss determines the ultimate sensitivity of CROW gyros. Resonator-based optical gyroscope's sensitivity for measuring rotation is enhanced via using the anomalous dispersion characteristic of superluminal light propagation, which can be also generated by using passive optical resonators.

  7. Simulation of self-organized waveguides for self-aligned coupling between micro- and nano-scale devices

    Science.gov (United States)

    Yoshimura, Tetsuzo

    2015-05-01

    We propose an optical coupling technique based on the reflective self-organized lightwave network (R-SOLNET), where optical devices with different core sizes are connected, for nano-scale-waveguide-based optical interconnects. Growth of R-SOLNET between a 3-μm-wide waveguide and a 600-nm-wide waveguide, on the core edge of which a luminescent target has been deposited, is simulated by the finite-difference time-domain method. The two waveguides are placed with gap distances ranging from 16 to 64 μm in a photopolymer with a refractive index that increases upon exposure to a write beam and luminescence. When a 400 nm wavelength write beam is introduced from the micro-scale waveguide, 470 nm luminescence is generated from the target. In the area where the write beam and the luminescence overlap, the refractive index increases rapidly. The write beam and the luminescence thus attract each other to merge into one through the self-focusing, forming a self-aligned coupling waveguide of R-SOLNET with a coupling loss of 1.5-1.8 dB, even when a lateral misalignment of 600 nm exists between them. This indicates that the R-SOLNET can be used as an optical solder to connect a micro-scale waveguide to a nano-scale waveguide. The optimum writing time required to attain the minimum coupling loss increases with increasing lateral misalignment. The dependence of the optimum writing time on the misalignment is reduced with increasing gap distance, and it almost vanishes when the distance is 64 μm, enabling unmonitored optical solder formation. R-SOLNET utilizing the two-photon photochemistry is briefly described as the next-generation SOLNET.

  8. 纳米级润滑与表面改性研究%Lubrication and Surface Modification in Nano Scale

    Institute of Scientific and Technical Information of China (English)

    张朝辉; 雒建斌

    2004-01-01

    A great improvement in nano technology has been witnessed in recent years. Major advances in two branches are discussed here: one is thin film lubrication (TFL) in nano scale and the other is nano-scale surface modification. The advancements of researches on TFL involve measuring techniques, film versus working parameter relations, mechanism exploration, and predicable numerical models. Surface modification to reduce pole-tip-recession (PTR) is introduced. The usage of a partial fluorinated hexaphenoxy cyclotriphosphazene, X-1P, in improving the thermal stability of the lube, and chemical mechanical polishing process coupled with nano particles are introduced. The results given will provide some insights of the modem nano technology.%纳米技术在过去的几年里取得了巨大的进展.关注其两个主要方面:纳米级的薄膜润滑与纳米表面改性研究.薄膜润滑(thin film lubrication,TFL)的研究进展包括薄膜润滑测试技术、薄膜润滑的膜厚-工况相关特性、机理探索以及数学计算预测模型等方面.介绍了降低极尖沉降(pole-tip-recession,PTR)的技术,使用含有氮磷的环状化合物--X-1P来提高润滑剂的热稳定性的方法,以及使用纳米粒子的化学机械抛光技术.这些研究成果揭示了现代纳米技术的一些重要特征.

  9. Characterization, engineering, and reliability of nano-scale high-k dielectrics and semiconductors interfaces

    Science.gov (United States)

    Seo, Kang-Ill

    The continued scaling of silicon complementary metal-oxide-semiconductor devices has lead to a need to replace the SiO2 gate insulator with high-k dielectric oxides, such as ZrO2 and HfO 2-based materials, to maintain a smaller leakage current without losing electrostatic gate control of the channel region. The main objectives of this dissertation are to understand the physical and electronic structure of the high-k/semiconductor interfaces, and based on that understanding, to develop new techniques that can modify or passivate the high-k /semiconductor interfaces for improved performance and reliability. First, we investigated chemical bonding structures and valence band alignments at the high-k (HfO2) and semiconductor (Si, Ge) interfaces using Synchrotron radiation photoemission spectroscopy. We found that highly non-stoichiometric GeOx exists at the HfO2/Ge interface, while stoichiometric SiOx was analyzed at the HfO 2/Si interface. From the valence band spectra the valence band offsets between HfO2 and Si or Ge were determined. Second, we demonstrated that the Zr-silicate interfacial layer (IL) can be formed between ZrO2 and a Si substrate by controlling the solid state reaction between Zr and an underlying SiO2/Si substrate. Incorporation of the metal-silicate layer improved the electrical properties, and reduced the stack equivalent oxide thickness. We also determined changes in chemical bonding at the HfO2/Si interface and associated electrical properties after the SiO2 IL is gettered by a Ti metal overlayer. We found that the removal of a part of SiO2 IL by oxygen-gettering Ti electrodes may be a promising approach for engineering ultrathin EOT without provoking a significant increase in interface trap density. Finally, for the first time, we developed a new technique to incorporate fluorine in high-k stack (HfO2/SiO2), and discovered that the negative bias temperature instability problems, such as positive charge trapping, interface trap generation, and C

  10. MATERIALS WITH COMPLEX ELECTRONIC/ATOMIC STRUCTURES

    Energy Technology Data Exchange (ETDEWEB)

    D. M. PARKIN; L. CHEN; ET AL

    2000-09-01

    We explored both experimentally and theoretically the behavior of materials at stresses close to their theoretical strength. This involves the preparation of ultra fine scale structures by a variety of fabrication methods. In the past year work has concentrated on wire drawing of in situ composites such as Cu-Ag and Cu-Nb. Materials were also fabricated by melting alloys in glass and drawing them into filaments at high temperatures by a method known as Taylor wire technique. Cu-Ag microwires have been drawn by this technique to produce wires 10 {micro}m in diameter that consist of nanoscale grains of supersaturated solid solution. Organogels formed from novel organic gelators containing cholesterol tethered to squaraine dyes or trans-stilbene derivatives have been studied from several different perspectives. The two types of molecules are active toward several organic liquids, gelling in some cases at w/w percentages as low as 0.1. While relatively robust, acroscopically dry gels are formed in several cases, studies with a variety of probes indicate that much of the solvent may exist in domains that are essentially liquid-like in terms of their microenvironment. The gels have been imaged by atomic force microscopy and conventional and fluorescence microscopy, monitoring both the gelator fluorescence in the case of the stilbene-cholesterol gels and, the fluorescence of solutes dissolved in the solvent. Remarkably, our findings show that several of the gels are composed of similarly appearing fibrous structures visible at the nano-, micro-, and macroscale.

  11. Methods of using structures including catalytic materials disposed within porous zeolite materials to synthesize hydrocarbons

    Science.gov (United States)

    Rollins, Harry W.; Petkovic, Lucia M.; Ginosar, Daniel M.

    2011-02-01

    Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

  12. Basalt: structural insight as a construction material

    Indian Academy of Sciences (India)

    SMRITI RAJ; V RAMESH KUMAR; B H BHARATH KUMAR; NAGESH R IYER

    2017-01-01

    The need for the development of novel and innovative materials is instrumental at every stage of societal improvements, leading to the overall development of a country. One such material of abundant source is basalt. The use of basalt in different forms like fibre, rod, grid and laminates has captured the interest of society from the 20th century onwards. Lately, basalt fibre has attracted attention as a possible construction material due to its properties such as high modulus of elasticity, high elastic strength, corrosion resistance, high-temperature resistance, extended operating temperature range and ease of handling. This paper explores the state of the art of basalt used in the construction industry with the overall layout of different subcategories of historical background starting from fibre development and different chemical and mechanical fibre properties to its applications in the field. Comparative studies have also been reported with respect to other high-strength fibre like glass, steel and carbon fibre based on different physical, chemical and mechanical properties. Along with these, a review hasbeen done on the usage of different basalt products like aggregate, rod, fibre, mesh, etc. in structural applications. The review also tends to identify critical constraints that restrain the implementation of basalt as a global construction material, thereby opening avenues of needed research. An insight on inconsistency reported in the literature with respect to the behaviour of basalt-fibre-reinforced composites is also expressed in this paper. The overall idea is to gain information and identify and prioritize research areas of the possible applications of basalt towards sustainable construction.

  13. Kinetics of nitrate adsorption and reduction by nano-scale zero valent iron (NZVI): Effect of ionic strength and initial pH

    DEFF Research Database (Denmark)

    Kim, Do-Gun; Hwang, Yuhoon; Shin, Hang-Sik

    2016-01-01

    Kinetic models for pollutants reduction by Nano-scale Zero Valent Iron (NZVI) were tested in this study to gain a better understanding and description of the reaction. Adsorption kinetic models and a heterogeneous catalytic reaction kinetic equation were proposed for nitrate removal and for ammon...

  14. Structural integrity--Searching the key factor to suppress the voltage fade of Li-rich layered cathode materials through 3D X-ray imaging and spectroscopy techniques

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yahong; Hu, Enyuan; Yang, Feifei; Corbett, Jeff; Sun, Zhihong; Lyu, Yingchun; Yu, Xiqian; Liu, Yijin; Yang, Xiao-Qing; Li, Hong (BNL); (SLAC); (UCSF); (Donghua); (Chinese Aca. Sci.)

    2016-10-24

    Li-rich layered materials are important cathode compounds used in commercial lithium ion batteries, which, however, suffers from some drawbacks including the so-called voltage fade upon electrochemical cycling. Here, our study employs novel transmission X-ray microscopy to investigate the electrochemical reaction induced morphological and chemical changes in the Li-rich Li2Ru0.5Mn0.5O3 cathode particles at the meso to nano scale. We performed combined X-ray spectroscopy, diffraction and microscopy experiments to systematically study this cathode material's evolution upon cycling as well as to establish a comprehensive understanding of the structural origin of capacity fade through 2D and 3D fine length scale morphology and heterogeneity change of this material. This work suggests that atomic manipulation (e.g. doping, substitution etc.) or nano engineering (e.g. nano-sizing, heterogeneous structure) are important strategies to mitigate the internal strain and defects induced by extensive lithium insertion/extraction. It also shows that maintaining the structural integrity is the key in designing and synthesizing lithium-rich layered materials with better cycle stability.

  15. Producing and optimizing novel materials and structures

    Science.gov (United States)

    Ashrafi, Mahdi

    2011-12-01

    A series of detailed experimental and finite element investigations were carried out to study the response of selected objects which are currently utilized for load carrying. These investigations were later applied to optimize the mechanical performance of the studied structures and materials. First, a number of experiments and detailed finite element simulations were carried out to study the response and failure of single lap joints with non-flat interface under uniaxial tension. The adherents were made from fiber reinforced epoxy composite and the custom-made mold allowed the fibers to follow the profile of the bonded joint interface. The experiments showed that the interface shape has significant effect on the mechanical behavior and strength of the bonded joints. Finite element simulations were performed to estimate the distribution of shear and peeling stresses along the bonded joints and the results were linked to the experimental investigations. Additional parametric calculations were also carried out to highlight the role of interface shape on the distribution of stresses, and inherently the overall strength and behavior of the bonded joints. In addition, the role of a central void on the distribution of the stresses in a bonded joint with flat and non-flat sinusoidal interfaces was investigated. The second topic concerns Wood Plastic Composites (WPC) which are widely used in the industry due to its durability, low cost, and anti-moisture properties in comparison with the natural wood. In this research, we have produced flout shaped WPC samples using African black wood powder and Phenolic resin in a hot compression molding set-up. Initial WPC composites were produced by systematically changing the wood volume fraction. Based on these results the optimum temperature, pressure and wood volume fraction for developing WPC in a form of a flute is developed. A series of experimental procedures were performed to improve mechanical properties of WPC samples by

  16. Mechanics and properties of composed materials and structures

    CERN Document Server

    Öchsner, Andreas; Altenbach, Holm

    2014-01-01

    This volume details the latest trends in characterization and developments of composed materials and structures, including textile composites, sandwich plates, hollow sphere structures, reinforced concrete as well as classical fibre reinforced materials.

  17. Comments on "Entransy analysis and optimization of performance of nano-scale irreversible Otto cycle operating with Maxwell-Boltzmann ideal gas"

    Science.gov (United States)

    Awad, M. M.

    2017-03-01

    The purpose of this discussion is to increase the awareness of the divergent views on the entransy concept among the readers of chemical physics. Comments are presented in particular on the paper by Ahmadi et al. (2016) where the authors used entransy dissipation in their analysis. Based on the view points of independent different groups of researchers world wide, I draw the attention of readers to the reality that entransy has no physical meaning. In this study, comments on the entransy, and in particular on the paper by Ahmadi et al. [1], are presented to increase the awareness of the divergent views on the entransy concept among the readers of chemical physics. Details of these comments are given below. Ahmadi et al. [1] applied the entransy analysis on the nano scale irreversible Otto cycle. The researchers considered five separate variables including compression process efficiency (ηC), the pressure ratio (x), expansion process efficiency (ηE), temperature of state point 1 (T1) and temperature of state point 3 (T3), as the decision parameters to assess the dimensionless ecological function, the dimensionless entransy dissipation, the ecological coefficient of performance and the energy efficiency of the nano scale irreversible Otto cycle executing thermodynamic analysis. During their analysis, they used entransy dissipation. It is well known that entransy dissipation analysis is a duplicate of entropy generation analysis as shown by Grazzini et al. [2]. Also, Lucia [3] showed that there is a link between the entropy generation and the entransy dissipation, underlining that the two approaches are similar. In addition, Bejan [4] showed that entransy dissipation is a number proportional to well known measures of irreversibility like lost exergy (destroyed available work) and entropy generation. Furthermore, Awad [5] mentioned that irreversibility (entropy generation, or exergy destruction) is a universal tendency in nature that is recognized as the second law

  18. Effects of Bias Pulsing on Etching of SiO2 Pattern in Capacitively-Coupled Plasmas for Nano-Scale Patterning of Multi-Level Hard Masks.

    Science.gov (United States)

    Kim, Sechan; Choi, Gyuhyun; Chae, Heeyeop; Lee, Nae-Eung

    2016-05-01

    In order to study the effects of bias pulsing on the etching characteristics of a silicon dioxide (SiO2) layer using multi-level hard mask (MLHM) structures of ArF photoresist/bottom anti-reflected coating/SiO2/amorphous carbon layer (ACL)/SiO2, the effects of bias pulsing conditions on the etch characteristics of a SiO2 layer with an ACL mask pattern in C4F8/CH2F2/O2/Ar etch chemistries were investigated in a dual-frequency capacitively-coupled plasma (CCP) etcher. The effects of the pulse frequency, duty ratio, and pulse-bias power in the 2 MHz low-frequency (LF) power source were investigated in plasmas generated by a 27.12 MHz high-frequency (HF) power source. The etch rates of ACL and SiO2 decreased, but the etch selectivity of SiO2/ACL increased with decreasing duty ratio. When the ACL and SiO2 layers were etched with increasing pulse frequency, no significant change was observed in the etch rates and etch selectivity. With increasing LF pulse-bias power, the etch rate of ACL and SiO2 slightly increased, but the etch selectivity of SiO2/ACL decreased. Also, the precise control of the critical dimension (CD) values with decreasing duty ratio can be explained by the protection of sidewall etching of SiO2 by increased passivation. Pulse-biased etching was successfully applied to the patterning of the nano-scale line and space of SiO2 using an ACL pattern.

  19. 纳米氢氧化镁的合成及其形貌控制%Synthesis and Morphology Control of Nano-Scaled Magnesium Hydroxide

    Institute of Scientific and Technical Information of China (English)

    徐林林; 张华; 杜喜玲; 祝建; 钟新华

    2009-01-01

    用乙醇和水的混合溶剂热法合成氢氧化镁纳米材料,并用透射电镜(TEM)和X射线衍射(XRD)表征其形貌和结构,同时考察了镁源、温度、反应时间、反应物浓度和溶剂热体系对氢氧化镁纳米材料形貌的影响,探索其生长机理.镁源通过改变氢氧化镁纳米粒子的结晶习性从而影响形貌,温度和反应时间受热力学和动力学的控制使氢氧化镁纳米材料的生长从六个等价面的取向生长向各向同性生长转变,从而导致形貌由六边形片状结构向圆形变化,反应物浓度和溶剂热体系影响成核快慢,从而影响氢氧化镁纳米材料的晶型.%The solvothermal synthesis and morphology control of nano-scaled magnesium hydroxide are reported. The impacts of a variety of factors, such as magnesium source, temperature, reaction time, concentration and solvent thermal system on the morphologies and crystal structure of Mg(OH)_2 are studied in detail. The mechanism of crystal growth is also explored. TEM and XRD results indicate that magnesium source with different anions could affect the morphology because of the polarity. Temperature, reaction time, concentration and solution system could result in the hexagon- and round- shaped nanosheets due to the kinetic and thermodynamic control, respectively, thus tuning the size of nanosheets.

  20. Mechanical and materials engineering of modern structure and component design

    CERN Document Server

    Altenbach, Holm

    2015-01-01

    This book presents the latest findings on mechanical and materials engineering as applied to the design of modern engineering materials and components. The contributions cover the classical fields of mechanical, civil and materials engineering, as well as bioengineering and advanced materials processing and optimization. The materials and structures discussed can be categorized into modern steels, aluminium and titanium alloys, polymers/composite materials, biological and natural materials, material hybrids and modern nano-based materials. Analytical modelling, numerical simulation, state-of-the-art design tools and advanced experimental techniques are applied to characterize the materials’ performance and to design and optimize structures in different fields of engineering applications.

  1. Corpuscle-Wave Duality of Discrete Systems at Nano-Scale Level

    Directory of Open Access Journals (Sweden)

    Kharkhardin Аnatolii Nikolaevich

    2016-09-01

    Full Text Available In the paper the results of study of wave properties for discrete systems with using of mathematical apparatus of discrete topology and application of its basic regularities for disperse materials, micro- and nanoparticles, topological and phase transportations as well as resulting effects and prognosis.

  2. Optimization of Structure and Material Properties for Solids Composed of Softening Material

    DEFF Research Database (Denmark)

    Bendsøe, Martin P.; Guedes, J.M.; J.M., Plaxton;

    1996-01-01

    Recent results on the design of material properties in the context of global structural optimization provide, in analytical form, a prediction of the optimal material tensor distributions for two or three dimensional continuum structures. The model developed for that purpose is extended here...... to cover the design of a structure and associated material properties for a system composed of a generic form of nonlinear softening material. As was established in the earlier study on design with linear materials, the formulation for combined 'material and structure' design with softening materials can...

  3. Engineered Nano-scale Ceramic Supports for PEM Fuel Cells. Tech Team Meeting Presentaion

    Energy Technology Data Exchange (ETDEWEB)

    Brosha, Eric L. [Los Alamos National Laboratory; Elbaz Alon, Lior [Los Alamos National Laboratory; Henson, Neil J. [Los Alamos National Laboratory; Rockward, Tommy [Los Alamos National Laboratory; Roy, Aaron [University of New Mexico; Serov, Alexey [University of New Mexico; Ward, Timothy [University of New Mexico

    2012-08-13

    Catalyst support durability is currently a technical barrier for commercialization of polymer electrolyte membrane (PEM) fuel cells, especially for transportation applications. Degradation and corrosion of the conventional carbon supports leads to losses in active catalyst surface area and, consequently, reduced performance. As a result, the goal of this work is to develop support materials that interact strongly with Pt, yet sustain bulk-like catalytic activities with very highly dispersed particles. Ceramic materials that are prepared using conventional solid-state methods have large grain sizes and low surface areas that can only be minimally ameliorated through grinding and ball milling. Other synthesis routes to produce ceramic materials must be investigated and utilized in order to obtain desired surface areas. In this work, several different synthesis methods are being utilized to prepare electronically conductive ceramic boride, nitride, and oxide materials with high surface areas and have the potential for use as PEMFC catalyst supports. Polymer-assisted deposition (PAD) and aerosol-through plasma (A-T-P) torch are among several methods used to obtain ceramic materials with surface areas that are equal to, or exceed Vulcan XC-72R supports. Cubic Mo-based ceramic phases have been prepared with average XRD-determined crystallite sizes as low as 1.6 nm (from full profile, XRD fitting) and a BET surface area exceeding 200 m{sup 2}/g. Additionally, black, sub-stoichiometric TiO{sub 2-x}, have been prepared with an average crystallite size in the 4 nm range and surface areas exceeding 250 m{sup 2}/gr. Pt disposition using an incipient wetness approach produced materials with activity for hydrogen redox reactions and ORR. Cyclic voltammetry data will be shown for a variety of potential Pt/ceramic catalysts. Initial experiments indicate enhanced Pt metal-support interactions as well. Plane wave periodic density functional calculations (VASP) are being used to

  4. A New Light Weight Structural Material for Nuclear Structures

    Energy Technology Data Exchange (ETDEWEB)

    Rabiei, Afsaneh [North Carolina State Univ., Raleigh, NC (United States)

    2016-01-14

    Radiation shielding materials are commonly used in nuclear facilities to attenuate the background ionization radiations to a minimum level for creating a safer workplace, meeting regulatory requirements and maintaining high quality performance. The conventional radiation shielding materials have a number of drawbacks: heavy concrete contains a high amount of elements that are not desirable for an effective shielding such as oxygen, silicon, and calcium; a well known limitation of lead is its low machinability and toxicity, which is causing a major environmental concern. Therefore, an effective and environmentally friendly shielding material with increased attenuation and low mass density is desirable. Close-cell composite metal foams (CMFs) and open-cell Al foam with fillers are light-weight candidate materials that we have studied in this project. Close-cell CMFs possess several suitable properties that are unattainable by conventional radiation shielding materials such as low density and high strength for structural applications, high surface area to volume ratio for excellent thermal isolation with an extraordinary energy absorption capability. Open-cell foam is made up of a network of interconnected solid struts, which allows gas or fluid media to pass through it. This unique structure provided a further motive to investigate its application as radiation shields by infiltrating original empty pores with high hydrogen or boron compounds, which are well known for their excellent neutron shielding capability. The resulting open-cell foam with fillers will not only exhibit light weight and high specific surface area, but also possess excellent radiation shielding capability and good processability. In this study, all the foams were investigated for their radiation shielding efficiency in terms of X-ray, gamma ray and neutron. X-ray transmission measurements were carried out on a high-resolution microcomputed tomography (microCT) system. Gamma-emitting sources: 3.0m

  5. Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite.

    Science.gov (United States)

    Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, Jürgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem

    2014-09-30

    The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties.

  6. Nano-structured support materials, their characterisation and serum protein profiling through MALDI/TOF-MS.

    Science.gov (United States)

    Najam-Ul-Haq, M; Rainer, M; Heigl, N; Szabo, Z; Vallant, R; Huck, C W; Engelhardt, H; Bischoff, K-D; Bonn, G K

    2008-02-01

    In the bioanalytical era, novel nano-materials for the selective extraction, pre-concentration and purification of biomolecules prior to analysis are vital. Their application as affinity binding in this regard is needed to be authentic. We report here the comparative application of derivatised materials and surfaces on the basis of nano-crystalline diamond, carbon nanotubes and fullerenes for the analysis of marker peptides and proteins by material enhanced laser desorption ionisation mass spectrometry MELDI-MS. In this particular work, the emphasis is placed on the derivatization, termed as immobilised metal affinity chromatography (IMAC), with three different support materials, to show the effectiveness of MELDI technique. For the physicochemical characterisation of the phases, near infrared reflectance spectroscopy (NIRS) is used, which is a well-established method within the analytical chemistry, covering a wide range of applications. NIRS enables differentiation between silica materials and different fullerenes derivatives, in a 3-dimensional factor-plot, depending on their derivatizations and physical characteristics. The method offers a physicochemical quantitative description in the nano-scale level of particle size, specific surface area, pore diameter, pore porosity, pore volume and total porosity with high linearity and improved precision. The measurement takes only a few seconds while high sample throughput is guaranteed.

  7. Achieving Thin Films with Micro/Nano-Scale Controllable Morphology by Glancing Angle Deposition Technique

    Institute of Scientific and Technical Information of China (English)

    JIANG Shao-Ji; WANG Chao-Yi; TANG Ji-Jia; HU Lin-Xin

    2008-01-01

    @@ We demonstrate that thin films with micro/nanometre controllable morphology can be fabricated by the glancing angle deposition (GLAD) technique which is a physical vapour deposition technique.In this technique, there are parameters which determine the morphology of the thin films: the incident angle, ratio of the deposition rate with respect to the substrate rotation rate, nature of the material being deposited, etc.We fabricate the morphology of column, pillar, helices, zigzag and study the parameters which determine morphology by given some examples of SEM.

  8. Micromachining And Pattering In Micro/Nano Scale On Macroscopic Areas

    Directory of Open Access Journals (Sweden)

    Marczak J.

    2015-09-01

    Full Text Available This paper presents detailed discussion of selected examples of laser technologies for the modification of solid surfaces, including topographic and microstructural changes as well as both these alterations simultaneously. Laser surface micromachining has just entered the new generation of technologies that are used in surface engineering. It will be shown on the examples of applications in bioengineering, on the base of the author’s own research, in modification of materials such as titanium and its alloys, diamond-like layers (DLC deposited on silicon and polymer substrates.

  9. Laser Materials Processing for NASA's Aerospace Structural Materials

    Science.gov (United States)

    Nagarathnam, Karthik; Hunyady, Thomas A.

    2001-01-01

    Lasers are useful for performing operations such as joining, machining, built-up freeform fabrication, and surface treatment. Due to the multifunctional nature of a single tool and the variety of materials that can be processed, these attributes are attractive in order to support long-term missions in space. However, current laser technology also has drawbacks for space-based applications. Specifically, size, power efficiency, lack of robustness, and problems processing highly reflective materials are all concerns. With the advent of recent breakthroughs in solidstate laser (e.g., diode-pumped lasers) and fiber optic technologies, the potential to perform multiple processing techniques in space has increased significantly. A review of the historical development of lasers from their infancy to the present will be used to show how these issues may be addressed. The review will also indicate where further development is necessary to realize a laser-based materials processing capability in space. The broad utility of laser beams in synthesizing various classes of engineering materials will be illustrated using state-of-the art processing maps for select lightweight alloys typically found on spacecraft. Both short- and long-term space missions will benefit from the development of a universal laser-based tool with low power consumption, improved process flexibility, compactness (e.g., miniaturization), robustness, and automation for maximum utility with a minimum of human interaction. The potential advantages of using lasers with suitable wavelength and beam properties for future space missions to the moon, Mars and beyond will be discussed. The laser processing experiments in the present report were performed using a diode pumped, pulsed/continuous wave Nd:YAG laser (50 W max average laser power), with a 1064 nm wavelength. The processed materials included Ti-6AI-4V, Al-2219 and Al-2090. For Phase I of this project, the laser process conditions were varied and optimized

  10. Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale

    Science.gov (United States)

    Hossain, R.; Pahlevani, F.; Quadir, M. Z.; Sahajwalla, V.

    2016-10-01

    Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels’ performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a combination of standard compression testing, X-ray diffraction, optical microstructure, electron backscattering diffraction imaging, electron probe micro-analysis, nano-indentation and micro-indentation measurements, we determined the mechanical stability of retained austenite and martensite in high carbon steel under compressive stress and identified the phase transformation mechanism, from the macro to the nano level. We found at the early stage of plastic deformation hexagonal close-packed (HCP) martensite formation dominates, while higher compression loads trigger body-centred tetragonal (BCT) martensite formation. The combination of this phase transformation and strain hardening led to an increase in the hardness of high carbon steel of around 30%. This comprehensive characterisation of stress induced phase transformation could enable the precise control of the microstructures of high carbon martensitic steels, and hence their properties.

  11. Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale.

    Science.gov (United States)

    Hossain, R; Pahlevani, F; Quadir, M Z; Sahajwalla, V

    2016-10-11

    Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels' performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a combination of standard compression testing, X-ray diffraction, optical microstructure, electron backscattering diffraction imaging, electron probe micro-analysis, nano-indentation and micro-indentation measurements, we determined the mechanical stability of retained austenite and martensite in high carbon steel under compressive stress and identified the phase transformation mechanism, from the macro to the nano level. We found at the early stage of plastic deformation hexagonal close-packed (HCP) martensite formation dominates, while higher compression loads trigger body-centred tetragonal (BCT) martensite formation. The combination of this phase transformation and strain hardening led to an increase in the hardness of high carbon steel of around 30%. This comprehensive characterisation of stress induced phase transformation could enable the precise control of the microstructures of high carbon martensitic steels, and hence their properties.

  12. Addressing the Recalcitrance of Cellulose Degradation through Cellulase Discovery, Nano-scale Elucidation of Molecular Mechanisms, and Kinetic Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Larry P., Bergstrom, Gary; Corgie, Stephane; Craighead, Harold; Gibson, Donna; Wilson, David

    2011-06-13

    This research project was designed to play a vital role in the development of low cost sugars from cellulosic biomass and contributing to the national effort to displace fossil fuel usage in the USA transportation sector. The goal was to expand the portfolio of cell wall degrading enzymes through innovative research at the nano-scale level, prospecting for novel cellulases and building a kinetic framework for the development of more effective enzymatic conversion processes. More precisely, the goal was to elucidate the molecular mechanisms for some cellulases that are very familiar to members of our research team and to investigate what we hope are novel cellulases or new enzyme combinations from the world of plant pathogenic fungi and bacteria. Hydrolytic activities of various cellulases and cellulase cocktails were monitored at the nanoscale of cellulose fibrils and the microscale of pretreated cellulose particles, and we integrated this insight into a heterogeneous reaction framework. The over-riding approach for this research program was the application of innovative and cutting edge optical and high-throughput screening and analysis techniques for observing how cellulases hydrolyze real substrates.

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

    CERN Document Server

    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 product of the superheating field for ideal flat surface and a suppression factor that contains 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 are derived in the framework of the London theory. As an immediate application, the suppression factor of the dirty Nb processed by the electropolishing is evaluated by using results of surface topographic study. The estimat...

  14. Opto-Electronic Characterization CdTe Solar Cells from TCO to Back Contact with Nano-Scale CL Probe

    Energy Technology Data Exchange (ETDEWEB)

    Moseley, John; Al-Jassim, Mowafak M.; Paudel, Naba; Mahabaduge, Hasitha; Kuciauskas, Darius; Guthrey, Harvey L.; Duenow, Joel; Yan, Yanfa; Metzger, Wyatt K.; Ahrenkiel, Richard K.

    2015-06-14

    We used cathodoluminescence (CL) (spectrum-per-pixel) imaging on beveled CdTe solar cell sections to investigate the opto-electronic properties of these devices from the TCO to the back contact. We used a nano-scale CL probe to resolve luminescence from grain boundary (GB) and grain interior (GI) locations near the CdS/CdTe interface where the grains are very small. As-deposited, CdCl2-treated, Cu-treated, and (CdCl2+Cu)-treated cells were analyzed. Color-coded CL spectrum imaging maps on bevels illustrate the distribution of the T=6 K luminescence transitions through the depth of devices with unprecedented spatial resolution. The CL at the GBs and GIs is shown to vary significantly from the front to the back of devices and is a sensitive function of processing. Supporting D-SIMS depth profile, TRPL lifetime, and C-V measurements are used to link the CL data to the J-V performance of devices.

  15. On the moving interface effect in the stimulated Brillouin scattering in a nano-scale photonic waveguide

    CERN Document Server

    Su, Xiao-Xing; Li, Xiao-Shuang

    2016-01-01

    We present a theoretical research on the moving interface (MI) effect that may exist as a nonnegligible surface complementarity to the bulk photoelastic effect in the stimulated Brillouin scattering (SBS) process in a nano-scale photonic waveguide. Compared with the existing literature, we gain a deeper insight into the detailed physical mechanism on how the MI effect come into play in the three-wave interaction process of SBS, by arguing that the field changes of an optical wave caused by the motion of a sharp interface are further amplitude-modulated by a rectangular-wave envelop synchronizing with the acoustic wave that drives the interface motion. Based on a detailed theoretical analysis on the amplitude-modulation process, the rigorous expressions of the field perturbations on a participating optical wave in SBS caused by the interface motion are derived. As a direct application of the obtained rigorous expressions of the optical field perturbations, we further derive the opto-acoustical coupling coeffic...

  16. Synthesis of nano-scale fast ion conducting cubic Li7La3Zr2O12

    Science.gov (United States)

    Sakamoto, Jeff; Rangasamy, Ezhiylmurugan; Kim, Hyunjoung; Kim, Yunsung; Wolfenstine, Jeff

    2013-10-01

    A solution-based process was investigated for synthesizing cubic Li7La3Zr2O12 (LLZO), which is known to exhibit the unprecedented combination of fast ionic conductivity, and stability in air and against Li. Sol-gel chemistry was developed to prepare solid metal-oxide networks consisting of 10 nm cross-links that formed the cubic LLZO phase at 600 ° C. Sol-gel LLZO powders were sintered into 96% dense pellets using an induction hot press that applied pressure while heating. After sintering, the average LLZO grain size was 260 nm, which is 13 times smaller compared to LLZO prepared using a solid-state technique. The total ionic conductivity was 0.4 mS cm-1 at 298 K, which is the same as solid-state synthesized LLZO. Interestingly, despite the same room temperature conductivity, the sol-gel LLZO total activation energy is 0.41 eV, which 1.6 times higher than that observed in solid-state LLZO (0.26 eV). We believe the nano-scale grain boundaries give rise to unique transport phenomena that are more sensitive to temperature when compared to the conventional solid-state LLZO.

  17. Dielectric strength of voidless BaTiO{sub 3} films with nano-scale grains fabricated by aerosol deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong-Ki; Lee, Young-Hie, E-mail: yhlee@kw.ac.kr [Department of Electronics Materials Engineering, Kwangwoon University, Seoul (Korea, Republic of); Lee, Seung-Hwan [Department of Electronics Materials Engineering, Kwangwoon University, Seoul (Korea, Republic of); R and D Center, Samwha Capacitor, Yongin (Korea, Republic of); In Kim, Soo; Woo Lee, Chang [Department of Nano and Electronic Physics, Kookmin University, Seoul (Korea, Republic of); Rag Yoon, Jung [R and D Center, Samwha Capacitor, Yongin (Korea, Republic of); Lee, Sung-Gap [Department of Ceramic Engineering, Engineering Research Institute, Gyeongsang National University, Jinju (Korea, Republic of)

    2014-01-07

    In order to investigate the dielectric strength properties of the BaTiO{sub 3} films with nano-scale grains with uniform grain size and no voids, BaTiO{sub 3} films were fabricated with a thickness of 1 μm by an AD process, and the fabricated films were sintered at 800, 900, and 1000 °C in air and reducing atmosphere. The films have superior dielectric strength properties due to their uniform grain size and high density without any voids. In addition, based on investigation of the leakage current (intrinsic) properties, it was confirmed that the sintering conditions of the reducing atmosphere largely increase leakage currents due to generated electrons and doubly ionized oxygen vacancies following the Poole-Frenkel emission mechanism, and increased leakage currents flow at grain boundary regions. Therefore, we conclude that the extrinsic breakdown factors should be eliminated for superior dielectric strength properties, and it is important to enhance grain boundaries by doping acceptors and rare-earth elements.

  18. Effects of nano-scaled particles on endothelial cell function in vitro: studies on viability, proliferation and inflammation.

    Science.gov (United States)

    Peters, Kirsten; Unger, Ronald E; Kirkpatrick, C James; Gatti, Antonietta M; Monari, Emanuela

    2004-04-01

    Recent studies give support for a connection between the presence of inorganic particles (of microm and nm size) in different organs and tissues and the development of inflammatory foci, called granulomas. As the potential source of particles (e.g. porcelain dental bridges) and the location of particle detection were topographically far apart, a distribution via the blood stream appears highly probable. Thus, endothelial cells, which line the inner surface of blood vessels, would come into direct contact with these particles, making particle-endothelial interactions potentially pathogenically relevant. The objective of this study was to evaluate the effects that five different nano-scaled particles (PVC, TiO2, SiO2, Co, Ni) have on endothelial cell function and viability. Therefore, human endothelial cells were exposed to different amounts of the above-mentioned particles. Although most particle types are shown to be internalised (except Ni-particles), only Co-particles possessed cytotoxic effects. Furthermore, an impairment of the proliferative activity and a pro-inflammatory stimulation of endothelial cells were induced by exposure to Co- and, to a lesser extent, by SiO2-particles. If a pro-inflammatory stimulation of endothelial cells occurs in vivo, a chronic inflammation could be a possible consequence.

  19. Longitudinal chirality, enhanced non-reciprocity, and nano-scale planar one-way guiding

    CERN Document Server

    Mazor, Yarden

    2012-01-01

    When a linear chain of plasmonic nano-particles is exposed to a transverse DC magnetic field, the chain modes are elliptically polarized, in a single plane parallel to the chain axis; hence, a novel longitudinal plasmon-rotation is created. If, in addition, the chain geometry possesses longitudinal rotation, e.g. by using ellipsoidal particles that rotate in the same plane as the plasmon rotation, strong non-reciprocity is created. The structure possesses a new kind of chirality--the longitudinal chirality--and supports one-way guiding. Since all particles rotate in the same plane, the geometry is planar and can be fabricated by printing leaf-like patches on a single plane. Furthermore, the magnetic field is significantly weaker than in previously reported one-way guiding structures. These properties are examined for ideal (lossless) and for lossy chains.

  20. Nano-scale optical actuation based on two-dimensional heterostructure photonic crystal cavities

    Science.gov (United States)

    Lin, Tong; Zhou, Guangya; Chau, Fook Siong; Tian, Feng; Deng, Jie

    2015-03-01

    Nowadays, nano-electro-mechanical systems (NEMS) actuators using electrostatic forces are facing the bottleneck of the electromagnetic interference which greatly degrades their performances. On the contrary, the hybrid circuits driven by optical gradient forces which are immune to the electromagnetic interference show prominent advantages in communication, quantum computation, and other application systems. In this paper we propose an optical actuator utilizing the optical gradient force generated by a hetero-structure photonic crystal cavity. This type of cavity has a longitudinal air-slot and characteristics of ultrahigh quality factor (Q) and ultra-small mode volume (V) which is capable of producing a much larger force compared with the waveguide-based structures. Due to the symmetry property, attractive optical gradient force is generated. Additionally, the optomechanical coefficient (gom) of this cavity is two orders of magnitude larger than that of the coupled nanobeam photonic crystal cavities. The 2D hetero-structure cavity, comb drives, folded beam suspensions and the displacement sensor compose the whole device. The cavity serves as the optical actuator whilst the butt-coupled waveguide acts as the displacement sensor which is theoretically proved to be insensitive to the temperature variations. As known, the thermo-optic effect prevails especially in the cavity-based structures. The butt-coupled waveguide can be used to decouple the thermal effect and the optoemchanical effect (OM) with the aid of comb drives. The results demonstrate that the proposed optical gradient force actuator show great potential in the future of all-optical reconfigurable circuits.

  1. Integration of Piezoelectric Sensing and Control for Nano-Scale Vibration Suppression in Hard Disk Drives

    OpenAIRE

    Felix, Sarah Helen

    2010-01-01

    This work takes an integrated mechatronic approach to combine a novel sensing scheme with appropriate control methods to improve vibration suppression in hard disk drives (HDDs). Thin-film piezoelectric ZnO strain sensors were integrated into a PZT-actuated HDD suspension by fabricating the sensors directly onto the steel suspension structure that carries the read/write head. This technology allowed for the addition of sensors at arbitrary locations without significantly altering the dynami...

  2. Integration of Piezoelectric Sensing and Control for Nano-Scale Vibration Suppression in Hard Disk Drives

    OpenAIRE

    Felix, Sarah Helen

    2010-01-01

    This work takes an integrated mechatronic approach to combine a novel sensing scheme with appropriate control methods to improve vibration suppression in hard disk drives (HDDs). Thin-film piezoelectric ZnO strain sensors were integrated into a PZT-actuated HDD suspension by fabricating the sensors directly onto the steel suspension structure that carries the read/write head. This technology allowed for the addition of sensors at arbitrary locations without significantly altering the dynami...

  3. Reversible Hydrogen Storage MaterialsStructure, Chemistry, and Electronic Structure

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Ian M. [University of Wisconsin-Madison; Johnson, Duane D. [Ames Lab., Iowa

    2014-06-21

    To understand the processes involved in the uptake and release of hydrogen from candidate light-weight metal hydride storage systems, a combination of materials characterization techniques and first principle calculation methods have been employed. In addition to conventional microstructural characterization in the transmission electron microscope, which provides projected information about the through thickness microstructure, electron tomography methods were employed to determine the three-dimensional spatial distribution of catalyst species for select systems both before and after dehydrogenation. Catalyst species identification as well as compositional analysis of the storage material before and after hydrogen charging and discharging was performed using a combination of energy dispersive spectroscopy, EDS, and electron energy loss spectroscopy, EELS. The characterization effort was coupled with first-principles, electronic-structure and thermodynamic techniques to predict and assess meta-stable and stable phases, reaction pathways, and thermodynamic and kinetic barriers. Systems studied included:NaAlH4, CaH2/CaB6 and Ca(BH4)2, MgH2/MgB2, Ni-Catalyzed Magnesium Hydride, TiH2-Catalyzed Magnesium Hydride, LiBH4, Aluminum-based systems and Aluminum

  4. LDRD final report on nano-scale engineering of smart membranes

    Energy Technology Data Exchange (ETDEWEB)

    Loy, D.A.; Jamison, G.M.; Assink, R.A. [and others

    1997-09-01

    A new approach to the fabrication of porous, amorphous inorganic membranes using organic pore templates was investigated. The pore templates were a new family of hybrid organic-inorganic monomers. As background for membrane work, the monomers were polymerized by sol-gel techniques to make crosslinked polymers. Molecular modeling was used to create computer simulations of the materials and provide insight into their composites, were then converted into porous silicas using low temperature oxygen plasma techniques. A select few of the monomers were copolymerized with silica monomers to form non-porous thin films on mesoporous substrates. The films were converted into porous silica thin films with thermal oxidations and the resulting membranes were tested for gas selectivities and flux.

  5. Size effects of nano-scale pinning centers on the superconducting properties of YBCO single grains

    Science.gov (United States)

    Moutalbi, Nahed; Noudem, Jacques G.; M'chirgui, Ali

    2014-08-01

    High pinning superconductors are the most promising materials for power engineering. Their superconducting properties are governed by the microstructure quality and the vortex pinning behavior. We report on a study of the vortex pinning in YBa2Cu3O7-x (YBCO) single grain with defects induced through the addition of insulating nano-particles. In order to improve the critical current density, YBCO textured bulk superconductors were elaborated using the Top Seeded Melt Texture and Growth process with different addition amounts of Al2O3 nano-particles. Serving as strong pinning centers, 0.05% excess of Al2O3 causes a significant enhancement of the critical current density Jc under self field and in magnetic fields at 77 K. The enhanced flux pinning achieved with the low level of alumina nano-particles endorses the effectiveness of insulating nano-inclusions to induce effectives pinning sites within the superconducting matrix. On the other side, we focused on the effect of the size of pinning centers on the critical current density. This work was carried out using two batches of alumina nano-particles characterized by two different particle size distributions with mean diameters PSD1 = 20 nm and PSD2 = 2.27 μm. The matching effects of the observed pinning force density have been compared. The obtained results have shown that the flux pinning is closely dependent on the size of the artificial pinning centers. Our results suggest that the optimization of the size of the artificial pinning centers is crucial to a much better understanding of the pinning mechanisms and therefore to insure high superconducting performance for the practical application of superconducting materials.

  6. Nano-scale morphology of melanosomes revealed by small-angle X-ray scattering.

    Directory of Open Access Journals (Sweden)

    Thomas Gorniak

    Full Text Available Melanosomes are highly specialized organelles that produce and store the pigment melanin, thereby fulfilling essential functions within their host organism. Besides having obvious cosmetic consequences--determining the color of skin, hair and the iris--they contribute to photochemical protection from ultraviolet radiation, as well as to vision (by defining how much light enters the eye. Though melanosomes can be beneficial for health, abnormalities in their structure can lead to adverse effects. Knowledge of their ultrastructure will be crucial to gaining insight into the mechanisms that ultimately lead to melanosome-related diseases. However, due to their small size and electron-dense content, physiologically intact melanosomes are recalcitrant to study by common imaging techniques such as light and transmission electron microscopy. In contrast, X-ray-based methodologies offer both high spatial resolution and powerful penetrating capabilities, and thus are well suited to study the ultrastructure of electron-dense organelles in their natural, hydrated form. Here, we report on the application of small-angle X-ray scattering--a method effective in determining the three-dimensional structures of biomolecules--to whole, hydrated murine melanosomes. The use of complementary information from the scattering signal of a large ensemble of suspended organelles and from single, vitrified specimens revealed a melanosomal sub-structure whose surface and bulk properties differ in two commonly used inbred strains of laboratory mice. Whereas melanosomes in C57BL/6J mice have a well-defined surface and are densely packed with 40-nm units, their counterparts in DBA/2J mice feature a rough surface, are more granular and consist of 60-nm building blocks. The fact that these strains have different coat colors and distinct susceptibilities to pigment-related eye disease suggest that these differences in size and packing are of biological significance.

  7. A demonstration of simple airfoils: Structural design and materials choices

    Energy Technology Data Exchange (ETDEWEB)

    Bunnell, L.R. (Pacific Northwest Lab., Richland, WA (United States)); Piippo, S.W. (Richland School District, WA (United States))

    1993-01-01

    An educational unit is presented for building and evaluating simple wing structures, in order to learn about materials choice and lightweight construction. This unit is appropriate for a high school materials science class or lower-division college courses in structural engineering, materials science, or aeronautical engineering.

  8. Direct optical imaging of structural inhomogeneities in crystalline materials.

    Science.gov (United States)

    Grigorev, A M

    2016-05-10

    A method for optical imaging of structural inhomogeneities in crystalline materials is proposed, based on the differences in the optical properties of the structural inhomogeneity and the homogeneous material near the fundamental absorption edge of the crystalline material. The method can be used to detect defects in both semiconductors and insulators.

  9. Ordered nano-scale dimple pattern formation on a titanium alloy (Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    Yue Wang

    2012-09-01

    Full Text Available Due to the many applications of nanostructured surfaces – including in biomaterials – there is a strong interest in cost- and time-efficient methods for their fabrication. Previously, our group established a simple electrochemical method generating nanoscale patterns on large areas of a number of different metal surfaces. They consist of dimples that are around 6-10 nm deep and hexagonally closed packed with a tunable periodicity of around 50 nm. Ordering requires careful tuning of the surface chemistry, which makes the translation of these findings to multi-component alloys non-obvious. Here, we demonstrate for the first time that such a pattern can also be achieved on the surface of an alloy, namely Ti-6Al-4V. This alloy is of particular interest for biomedical implants. While dimple formation on the main component metals titanium and aluminum has previously been reported (albeit under conditions that differ from each other, we now also report dimple formation on pure vanadium surfaces to occur under very different conditions. Dimple formation occurs preferentially on the (dominant α-phase grains of the alloy. The size of dimples of the alloy material is subject to the electropolishing potential, electrolyte concentration and surface chemical composition, which gives us the opportunity to control the surface features. Since a main application of this alloy are biomedical implants, this level of control will be an important tool for accommodating cell growth.

  10. Nano-scale analysis of titanium dioxide fingerprint-development powders

    Science.gov (United States)

    Reynolds, A. J.; Jones, B. J.; Sears, V.; Bowman, V.

    2008-08-01

    Titanium dioxide based powders are regularly used in the development of latent fingerprints on dark surfaces. For analysis of prints on adhesive tapes, the titanium dioxide is suspended in a surfactant and used in the form of a small particle reagent (SPR). Analysis of commercially available products shows varying levels of effectiveness of print development, with some powders adhering to the background as well as the print. Scanning electron microscopy (SEM) images of prints developed with different powders show a range of levels of aggregation of particles. Analytical transmission electron microscopy (TEM) of the fingerprint powder shows TiO2 particles with a surrounding coating, tens of nanometres thick, consisting of Al and Si rich material. X ray photoelectron spectroscopy (XPS) is used to determine the composition and chemical state of the surface of the powders; with a penetration depth of approximately 10nm, this technique demonstrates differing Ti: Al: Si ratios and oxidation states between the surfaces of different powders. Levels of titanium detected with this technique demonstrate variation in the integrity of the surface coating. The thickness, integrity and composition of the Al/Si-based coating is related to the level of aggregation of TiO2 particles and efficacy of print development.

  11. Nano-scale composition of commercial white powders for development of latent fingerprints on adhesives.

    Science.gov (United States)

    Jones, B J; Reynolds, A J; Richardson, M; Sears, V G

    2010-09-01

    Titanium dioxide based powders are regularly used in the development of latent fingerprints on dark surfaces. For analysis of prints on adhesive tapes, the titanium dioxide can be suspended in a surfactant and used in the form of a powder suspension. Commercially available products, whilst having nominally similar composition, show varying levels of effectiveness of print development, with some powders adhering to the background as well as the print. X-ray fluorescence (XRF), analytical transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and laser particle sizing of the fingerprint powders show TiO(2) particles with a surrounding coating, tens of nanometres thick, consisting of Al and Si rich material, with traces of sodium and sulphur. Such aluminosilicates are commonly used as anti-caking agents and to aid adhesion or functionality of some fingerprint powders; however, the morphology, thickness, coverage and composition of the aluminosilicates are the primary differences between the white powder formulations and could be related to variation in the efficacy of print development.

  12. Nano-scale analysis of titanium dioxide fingerprint-development powders

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, A J; Jones, B J [Experimental Techniques Centre, Brunei University, Kingston Lane, Uxbridge, Middlesex, UB8 3PH (United Kingdom); Sears, V; Bowman, V [Fingerprint and Footwear Forensics, Home Office Scientific Development Branch, Sandridge, St Albans, Hertfordshire, AL4 9HQ (United Kingdom)], E-mail: b.j.jones@physics.org

    2008-08-15

    Titanium dioxide based powders are regularly used in the development of latent fingerprints on dark surfaces. For analysis of prints on adhesive tapes, the titanium dioxide is suspended in a surfactant and used in the form of a small particle reagent (SPR). Analysis of commercially available products shows varying levels of effectiveness of print development, with some powders adhering to the background as well as the print. Scanning electron microscopy (SEM) images of prints developed with different powders show a range of levels of aggregation of particles. Analytical transmission electron microscopy (TEM) of the fingerprint powder shows TiO{sub 2} particles with a surrounding coating, tens of nanometres thick, consisting of Al and Si rich material. X ray photoelectron spectroscopy (XPS) is used to determine the composition and chemical state of the surface of the powders; with a penetration depth of approximately 10nm, this technique demonstrates differing Ti: Al: Si ratios and oxidation states between the surfaces of different powders. Levels of titanium detected with this technique demonstrate variation in the integrity of the surface coating. The thickness, integrity and composition of the Al/Si-based coating is related to the level of aggregation of TiO{sub 2} particles and efficacy of print development.

  13. Oxidation performance of nano-scale multilayer coatings on {gamma}-TiAl

    Energy Technology Data Exchange (ETDEWEB)

    Ross, I M; Rainforth, W M; Zhou, Z; Walker, J C [Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Reinhard, C; Ehiasarian, A P; Hovsepian, P E [Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield, S1 1WB (United Kingdom); Braun, R [German Aerospace Centre, Institute of Materials Research, 51170 Koeln (Germany)], E-mail: i.ross@shef.ac.uk

    2008-08-15

    There is a major drive to introduce {gamma}-TiAl into gas turbine engines in order to reduce weight. However, this will require the development of coatings that protect against oxidation at high temperature, but do not adversely affect the mechanical properties. This work reports the high temperature degradation mechanisms of a nanoscale CrAlYN/CrN multilayer coating deposited on {gamma}-TiAl(8Nb) by a combined high power impulse magnetron sputtering / unbalanced magnetron sputtering. Detailed TEM/STEM of FIB prepared specimens from isothermal static oxidation tests at 850 deg. C for up to 1030 hours is presented. The evolution of the complex oxide structure and the implications for future coating development is discussed.

  14. Magnetotransport in Graphene on the Nano Scale measured by Scanning Tunneling Potentiometry

    Science.gov (United States)

    Willke, Philip; Druga, Thomas; Kotzott, Thomas; Ulbrich, Rainer; Schneider, Alexander; Wenderoth, Martin

    The method of scanning tunneling potentiometry (STP) has been introduced by Muralt and Pohl as a technique for mapping the electrochemical potential locally. Here we present a new home-built low-temperature STP setup with applicable magnetic field of up to 6T to study the spatial evolution of the voltage drop at extended defects in graphene with high-resolution. We show that the voltage drop at a monolayer-bilayer boundary in graphene clearly extends spatially up to a few nanometers into the bilayer and hence is not located strictly at the structural defect. Moreover, different scattering mechanisms can be disentangled. Besides, we perform magnetotransport STP measurements mapping the local electrochemical potential as a function of the applied magnetic field. This allows us to identify localized and delocalized contributions to the magnetoresistance in epitaxial-grown graphene and to reveal the contribution of defects. This work was supported by the priority program 1459 ``Graphene'' of the German Science Foundation.

  15. Non-linear, non-monotonic effect of nano-scale roughness on particle deposition in absence of an energy barrier: Experiments and modeling

    Science.gov (United States)

    Jin, Chao; Glawdel, Tomasz; Ren, Carolyn L.; Emelko, Monica B.

    2015-12-01

    Deposition of colloidal- and nano-scale particles on surfaces is critical to numerous natural and engineered environmental, health, and industrial applications ranging from drinking water treatment to semi-conductor manufacturing. Nano-scale surface roughness-induced hydrodynamic impacts on particle deposition were evaluated in the absence of an energy barrier to deposition in a parallel plate system. A non-linear, non-monotonic relationship between deposition surface roughness and particle deposition flux was observed and a critical roughness size associated with minimum deposition flux or “sag effect” was identified. This effect was more significant for nanoparticles (surface roughness on particle deposition by unifying hydrodynamic forces (using the most current approaches for describing flow field profiles and hydrodynamic retardation effects) with appropriately modified expressions for DLVO interaction energies, and gravity forces in one model and 2) a foundation for further describing the impacts of more complicated scales of deposition surface roughness on particle deposition.

  16. Unique micro- and nano-scale mineralization pattern of human osteogenesis imperfecta type VI bone.

    Science.gov (United States)

    Fratzl-Zelman, Nadja; Schmidt, Ingo; Roschger, Paul; Roschger, Andreas; Glorieux, Francis H; Klaushofer, Klaus; Wagermaier, Wolfgang; Rauch, Frank; Fratzl, Peter

    2015-04-01

    Osteogenesis imperfecta (OI) is a heterogeneous group of inheritable connective tissue disorders characterized by mutation in genes involved in collagen synthesis and leading to increased bone fragility, low bone mass, impaired bone material properties and abnormally high bone matrix mineralization. Recessive OI type VI is caused by mutation in SERPINF1 leading to a loss-of-function of pigment epithelium-derived factor (PEDF) a collagen-binding protein with potent antiangiogenic activity. Affected patients develop a severe OI phenotype with a striking histological characteristic, rare in other OI types, of an excess of osteoid tissue and prolonged mineralization lag time. To get insights into matrix mineralization, we evaluated biopsies from 9 affected children by quantitative and by high-resolution backscattered electron imaging and assessed bone mineralization density distribution. Thickness, shape and arrangement of mineral particles were measured in a subset of 4 patients by synchrotron small angle X-ray scattering. Typical calcium content in the bone matrix was found to be increased compared to controls, even exceeding values found previously in OI patients with collagen-gene mutations. A main characteristic however, is the coexistence of this highly mineralized bone matrix with seams showing abnormally low mineral content. Atypical collagen fibril organization was found in the perilacunar region of young osteocytes, suggesting a disturbance in the early steps of mineralization. These observations are consistent with the presence of a heterogeneous population of mineral particles with unusual size, shape and arrangement, especially in the region with lower mineral content. The majority of the particles in the highly mineralized bone areas were less disorganized, but smaller and more densely packed than in controls and in previously measured OI patients. These data suggest that the lack of PEDF impairs a proper osteoblast-osteocyte transition and consequently

  17. Iron and aluminum hydroxide nanoparticles in the environment: from nano-scale to the field processes

    Science.gov (United States)

    Bazilevskaya, Ekaterina

    The objective of this doctoral research was to increase scientific understanding of the behavior of Fe and Al hydroxide nanoparticles in soils. These particles are of great environmental importance due to their ability to retain and transport nutrients and contaminants. Three studies were undertaken at different scales, which are documented in three manuscripts included in this dissertation. The first study examined the rate constants for goethite (alpha-FeOOH) crystallization from nano-particulate Fe hydroxide suspensions in the absence (0% Al) and presence (2% Al) of aluminum. One of the merits of this study was the application of a multivariate curve resolution analysis (MCR) of infrared spectra to environmentally important mixed Fe-Al hydroxide colloids in order to quantify goethite content in poorly-crystalline mixtures. Obtained rate constants were found to be equal to (7.64+/-0.67)x10-7 s-1 for 0% Al and (4.5+/-0.21) x10-7 s-1 for 2% Al hydroxides. Dissolution-precipitation mechanism was dominant in the process of goethite transformation to ferrihydrite. Further growth of goethite crystals took place either by aggregation mechanism to form polycrystalline agglomerates or alternatively by Oswald ripening to form large single crystals. The presence of aqueous Al species "poisoned" goethite's surface by disrupting the formation of hydrogen bonds thus increasing the number of non-stoichiometric hydroxyls. The second study addressed changes of mineral composition in mixed Fe-Al hydroxide nanoparticles as a function of Al-substitution and reaction time. It was found that low Al concentrations (2-8 mol. %) lead to formation of moderately crystalline Al-goethite upon ageing, while at medium Al concentrations (10-20%) colloidal suspensions remained stable for the duration of the whole experiment (54 days), goethite formation was completely retarded, and less crystalline intermediate structure were formed. At 25% Al substitution, gibbsite Al(OH)3 microcrystalline

  18. Nano-scale engineering using lead chalcogenide nanocrystals for opto-electronic applications

    Science.gov (United States)

    Xu, Fan

    Colloidal quantum dots (QDs) or nanocrystals of inorganic semiconductors exhibit exceptional optoelectronic properties such as tunable band-gap, high absorption cross-section and narrow emission spectra. This thesis discusses the characterizations and physical properties of lead-chalcogenide nanocrystals, their assembly into more complex nanostructures and applications in solar cells and near-infrared light-emitting devices. In the first part of this work, we demonstrate that the band edge emission of PbS quantum dots can be tuned from the visible to the mid-infrared region through size control, while the self-attachment of PbS nanocrystals can lead to the formation of 1-D nanowires, 2-D quantum dot monolayers and 3-D quantum dot solids. In particular, the assembly of closely-packed quantum dot solids has attracted enormous attention. A series of distinctive optoelectronic properties has been observed, such as superb multiple exciton generation efficiencies, efficient hot-electron transfer and cold-exciton recycling. Since the surfactant determines the quantum dot surface passivation and inter dot electronic coupling, we examine the influence of different cross-linking surfactants on the optoelectronic properties of the quantum dot solids. Then, we discuss the ability to tune the quantum dot band-gap combined with the controllable assembly of lead-chalcogenide quantum dots, which opens new possibilities to engineer the properties of quantum dot solids. The PbS and PbSe quantum dot cascade structures and PbS/PbSe quantum dot heterojunctions are assembled using the layer-by-layer deposition method. We show that exciton funnelling and trap state-bound exciton recycling in the quantum dot cascade structure dramatically enhances the quantum dots photoluminescence. Moreover, we show that both type-I and type-II PbS/PbSe quantum dot heterojunctions can be assembled by carefully choosing the quantum dot sizes. In type-I heterojunctions, the excited electron-hole pairs tend

  19. Contribution of nano-scale effects to the total efficiency of converters of thermal neutrons on the basis of gadolinium foils

    CERN Document Server

    Abdushukurov, D A; Muminov, Kh Kh; Chistyakov, D Yu

    2008-01-01

    We study the influence of nano-scale layers of converters made from natural gadolinium and its 157 isotope into the total efficiency of registration of thermal neutrons. Our estimations show that contribution of low-energy Auger electrons with the runs about nanometers in gadolinium, to the total efficiency of neutron converters in this case is essential and results in growth of the total efficiency of converters. The received results are in good consent to the experimental data.

  20. Amended Electric Field Distribution: A Reliable Technique for Electrical Performance Improvement in Nano scale SOI MOSFETs

    Science.gov (United States)

    Ramezani, Zeinab; Orouji, Ali A.

    2017-04-01

    To achieve reliable transistors, we propose a new silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistor (MOSFET) with an amended electric field in the channel for improved electrical and thermal performance, with an emphasis on current leakage improvement. The amended electric field leads to lower electric field crowding and thereby we assume enhanced reliability, leakage current, gate-induced drain leakage (GIDL), and electron temperature. To modify the electric field distribution, an additional rectangular metal region (RMR) is utilized in the buried oxide of the SOI MOSFET. The location and dimensions of the RMR have been carefully optimized to achieve the best results. The electrical, thermal, and radiofrequency characteristics of the proposed structure were analyzed using two-dimensional (2-D) numerical simulations and compared with the characteristics of the conventional, fully depleted SOI MOSFET (C-SOI). Also, critical short-channel effects (SCEs) such as threshold voltage, drain-induced barrier lowering (DIBL), subthreshold slope degradation, hot-carrier effect, GIDL, and leakage power consumption are improved. According to the results obtained, the proposed nano SOI MOSFET is a reliable device, especially for use in low-power and high-temperature applications.

  1. Thermodynamically induced particle transport: Order-by-induction and entropic trapping at the nano-scale

    Science.gov (United States)

    Patitsas, S. N.

    2015-10-01

    A theory for thermodynamic induction (TI) under isothermal conditions is presented. This includes a treatment of the Helmholtz free energy budget available for a gate variable to utilize towards aiding another variable's approach towards thermodynamic equilibrium. This energy budget could be used to help create interesting physical structures and examples of order-by-induction. I also show how to treat TI in the continuum limit which can be obtained from a variational principle. Several important examples of isothermal TI have been discussed, including a type of electromigration that may be detectable in electrolytes, superfluids and semiconductors. As an example of a bottlenecked system exhibiting enhanced TI, manipulation of atoms and molecules by STM has been discussed in detail. My considerations provide strong support for microscopic bond-breaking mechanisms being governed by a general thermodynamic principle. In particular, I show that induced entropy trapping can explain the level of control that sliding-type manipulations demonstrate. The most reasonable choices for the parameters input into the simple formula give a threshold condition for STM manipulations that is strikingly close to what is required to match results reported in the literature. My continuum model predicts the shape of the adsorbate potential well for the STM case and from this I predict a level of force detectable by AFM. A final proposal, and example of order-by-induction, predict a long tether may be constructed between sample and tip that is just one atom thick.

  2. Hierarchical Optimization of Material and Structure

    DEFF Research Database (Denmark)

    Rodrigues, Helder C.; Guedes, Jose M.; Bendsøe, Martin P.

    2002-01-01

    This paper describes a hierarchical computational procedure for optimizing material distribution as well as the local material properties of mechanical elements. The local properties are designed using a topology design approach, leading to single scale microstructures, which may be restricted...... in various ways, based on design and manufacturing criteria. Implementation issues are also discussed and computational results illustrate the nature of the procedure....

  3. Structured Piezoelectric Composites: Materials and Applications

    NARCIS (Netherlands)

    Van den Ende, D.A.

    2012-01-01

    The piezoelectric effect, which causes a material to generate a voltage when it deforms, is very suitable for making integrated sensors, and (micro-) generators. However, conventional piezoelectric materials are either brittle ceramics or certain polymers with a low thermal stability, which limits t

  4. Structural materials: What can we learn from nature?

    Directory of Open Access Journals (Sweden)

    Taylor David

    2013-11-01

    Full Text Available The mechanical properties of materials are of vital importance in the natural world. Over millions of years of evolution, Nature has created materials capable of resisting mechanical forces, in our bodies and in those of other animals and plants. Throughout history human beings have created new materials; in particular many materials developed over the last 100 years have greatly surpassed natural materials in their mechanical properties and durability. So is there anything which Nature can still teach us about making and maintaining structural materials? This talk will consider some of the “tricks” which Nature uses, such as bottom-up fabrication processes, functionally graded structures and materials with the capacity for continual self-monitoring and repair. It will be shown that some of these tricks can be used by materials scientists, but some aspects of the behaviour of natural materials are not suitable for copying into manmade structures.

  5. Perspective: Role of structure prediction in materials discovery and design

    Science.gov (United States)

    Needs, Richard J.; Pickard, Chris J.

    2016-05-01

    Materials informatics owes much to bioinformatics and the Materials Genome Initiative has been inspired by the Human Genome Project. But there is more to bioinformatics than genomes, and the same is true for materials informatics. Here we describe the rapidly expanding role of searching for structures of materials using first-principles electronic-structure methods. Structure searching has played an important part in unraveling structures of dense hydrogen and in identifying the record-high-temperature superconducting component in hydrogen sulfide at high pressures. We suggest that first-principles structure searching has already demonstrated its ability to determine structures of a wide range of materials and that it will play a central and increasing part in materials discovery and design.

  6. Structured materials for catalytic and sensing applications

    Science.gov (United States)

    Hokenek, Selma

    The optical and chemical properties of the materials used in catalytic and sensing applications directly determine the characteristics of the resultant catalyst or sensor. It is well known that a catalyst needs to have high activity, selectivity, and stability to be viable in an industrial setting. The hydrogenation activity of palladium catalysts is known to be excellent, but the industrial applications are limited by the cost of obtaining catalyst in amounts large enough to make their use economical. As a result, alloying palladium with a cheaper, more widely available metal while maintaining the high catalytic activity seen in monometallic catalysts is, therefore, an attractive option. Similarly, the optical properties of nanoscale materials used for sensing must be attuned to their application. By adjusting the shape and composition of nanoparticles used in such applications, very fine changes can be made to the frequency of light that they absorb most efficiently. The design, synthesis, and characterization of (i) size controlled monometallic palladium nanoparticles for catalytic applications, (ii) nickel-palladium bimetallic nanoparticles and (iii) silver-palladium nanoparticles with applications in drug detection and biosensing through surface plasmon resonance, respectively, will be discussed. The composition, size, and shape of the nanoparticles formed were controlled through the use of wet chemistry techniques. After synthesis, the nanoparticles were analyzed using physical and chemical characterization techniques such as X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Scanning Transmission Electron Microscopy- Energy-Dispersive Spectrometry (STEM-EDX). The Pd and Ni-Pd nanoparticles were then supported on silica for catalytic testing using mass spectrometry. The optical properties of the Ag-Pd nanoparticles in suspension were further investigated using ultraviolet-visible spectrometry (UV-Vis). Monometallic palladium particles have

  7. Particles from a Diesel ship engine: Mixing state on the nano scale and cloud condensation abilities

    Science.gov (United States)

    Lieke, K. I.; Rosenørn, T.; Fuglsang, K.; Frederiksen, T.; Butcher, A. C.; King, S. M.; Bilde, M.

    2012-04-01

    . Results of transmission electron microscopy revealed salt condensates of nanometer size attached to soot particles. High resolution structural analysis of single particles shows that three different phases (graphitic soot, crystalline salt and amorphous condensed organic matter) may be present in the same particle volume. A closure between CCN activation curves, EM samples, and SMPS size distribution will be presented and used to identify climate active parts in single particles. ACKNOWLEDGEMENTS We thank the Danish Agency for Science, Technology and Innovation for support through the NaKIM project (www.nakim.dk).

  8. Lectures on Composite Materials for Aircraft Structures,

    Science.gov (United States)

    1982-10-01

    lectures are related to structural applications of composites . In Lecture 7, the basic theory that is needed for composite structural analysis is...which composites have been taken up for aeronautical applications. Several specific applications of composites in aircraft structures am described in

  9. Material with core-shell structure

    Science.gov (United States)

    Luhrs, Claudia; Richard, Monique N.; Dehne, Aaron; Phillips, Jonathan; Stamm, Kimber L.; Fanson, Paul T.

    2011-11-15

    Disclosed is a material having a composite particle, the composite particle including an outer shell and a core. The core is made from a lithium alloying material and the outer shell has an inner volume that is greater in size than the core of the lithium alloying material. In some instances, the outer mean diameter of the outer shell is less than 500 nanometers and the core occupies between 5 and 99% of the inner volume. In addition, the outer shell can have an average wall thickness of less than 100 nanometers.

  10. Nano-scale zero valent iron transport in a variable aperture dolomite fracture and a glass fracture

    Science.gov (United States)

    Mondal, P.; Sleep, B. E.; Cui, Z.; Zhou, Z.

    2014-12-01

    Experiments and numerical simulations are being performed to understand the transport behavior of carboxymethyl cellulose polymer stabilized nano-scale zero valent iron (nZVI) in a variable aperture dolomite rock fracture and a variable aperture glass replica of a fractured slate. The rock fracture was prepared by artificially inducing a fracture in a dolomite block along a stylolite, and the glass fracture was prepared by creating molds with melted glass on two opposing sides of a fractured slate rock block. Both of the fractures were 0.28 m in length and 0.21 m in width. Equivalent hydraulic apertures are about 110 microns for the rock fracture and 250 microns for the glass replica fracture. Sodium bromide and lissamine green B (LGB) serve as conservative tracers in the rock fracture and glass replica fracture, respectively. A dark box set-up with a light source and digital camera is being used to visualize the LGB and CMC-nZVI movement in the glass fracture. Experiments are being performed to determine the effects of water specific discharge and CMC concentration on nZVI transport in the fractures. Transmission electron microscopy, dynamic light scattering, and UV-visual spectrophotometry were performed to determine the stability and characteristics of the CMC-nZVI mixture. The transport of bromide, LGB, CMC, and CMC-nZVI in both fractures is being evaluated through analysis of the effluent concentrations. Time-lapse images are also being captured for the glass fracture. Bromide, LGB, and CMC recoveries have exceeded 95% in both fractures. Significant channeling has been observed in the fractures for CMC transport due to viscous effects.

  11. Nano scale dynamics of bubble nucleation in confined liquid subjected to rapid cooling: Effect of solid-liquid interfacial wettability

    Science.gov (United States)

    Hasan, Mohammad Nasim; Rabbi, Kazi Fazle; Mukut, K. M.; Tamim, Saiful Islam; Faisal, A. H. M.

    2017-06-01

    This study focuses on the occurrence of bubble nucleation in a liquid confined in a nano scale confinement and subjected to rapid cooling at one of its wall. Due to the very small size scale of the present problem, we adopt the molecular dynamics (MD) approach. The liquid (Argon) is confined within two solid (Platinum) walls. The temperature of the upper wall of the confinement is maintained at 90 K while the lower wall is being cooled rapidly to 50 K from initial equilibrium temperature of 90 K within 0.1 ns. This results in the nucleation and formation of nanobubbles in the liquid. The pattern of bubble nucleation has been studied for three different conditions of solid-liquid interfacial wettability such as hydrophilic, hydrophobic and neutral. Behavior of bubble nucleation is significantly different in the three case of solid-liquid interfacial wettability. In case of the hydrophobic confinement (weakly adsorbing), the liquid cannot achieve deeper metastability; vapor layers appear immediately on the walls. In case of the neutral confinement (moderately adsorbing), bubble nucleation is promoted by the walls where the nucleation is heterogeneous. In case of the hydrophilic walls (strongly adsorbing) bubbles are developed inside the liquid; that is the nucleation process is homogeneous. The variation in bubble nucleation under different conditions of surface wettability has been studied by the analysis of number density distribution, spatial temperature distribution, spatial number density distribution and heat flux through the upper and lower walls of the confinement. The present study indicates that the variation of heat transfer efficiency due to different surface wettability has significant effect on the size, shape and location of bubble nucleation in case rapid cooling of liquid in nano confinement.

  12. Computational Design of Ageless Structural Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Crack initiation and propagation is a dominant failure mode for many materials and applications – usually managed via damage tolerance approaches." ...

  13. Effects of Particle-Wall Interactions on the Thermodynamic Behavior of Gases at the Nano Scale

    Directory of Open Access Journals (Sweden)

    Fatih Ozturk

    2011-11-01

    ="Subtle Emphasis" /> The thermodynamic behavior of gases confined in nano structures is considerably different than those in macro ones due to the effects of both particle-wall interactions and the wave character of particles. The homogeneous density distribution of a gas at thermodynamic equilibrium is disturbed by these effects. Because of particle-wall interactions, the local density of a gas changes drastically near the domain boundaries. Also, the wave character of the particles causes an inhomogeneous density distribution, especially near the boundaries. Consequently, the apparent density (number of particles over the domain volume is different than the real one. All the density-dependent thermodynamic

  14. 2nd Generation RLV Airframe Structures and Materials

    Science.gov (United States)

    Johnson, Theodore F.

    2000-01-01

    The goals and objectives of the project summarized in this viewgraph presentation are the following: (1) Develop and demonstrate verified airframe and cryotank structural design and analysis technologies, including damage tolerance, safety, reliability, and residual strength technologies, robust nonlinear shell and cryotank analysis technologies, high-fidelity analysis and design technologies for local structural detail features and joints, and high-fidelity analysis technologies for sandwich structures; (2) Demonstrate low cost, robust materials and processing, including polymeric matrix composite (PMC) and metallic materials and processing, and refractory composite and metallic hot structures materials and processing; (3) Develop and demonstrate robust airframe structures and validated integrated airframe structural concepts, including low cost fabrication and joining, operations efficient designs and inspection techniques (non-destructive evaluation), scale-up and integrated thermal structure tests, and airframe structures IVHM; (4) Demonstrate low cost, robust repair techniques; and (5) Develop verified integrated airframe structural concepts, including integrated structural concepts.

  15. Development of Steel Foam Materials and Structures

    Energy Technology Data Exchange (ETDEWEB)

    Kenneth Kremer; Anthony Liszkiewicz; James Adkins

    2004-10-20

    In the past few years there has been a growing interest in lightweight metal foams. Demands for weight reduction, improved fuel efficiency, and increased passenger safety in automobiles now has manufacturers seriously considering the use of metal foams, in contrast to a few years ago, when the same materials would have been ruled out for technical or economical reasons. The objective of this program was to advance the development and use of steel foam materials, by demonstrating the advantages of these novel lightweight materials in selected generic applications. Progress was made in defining materials and process parameters; characterization of physical and mechanical properties; and fabrication and testing of generic steel foam-filled shapes with compositions from 2.5 wt.% to 0.7 wt.% carbon. A means of producing steel foam shapes with uniform long range porosity levels of 50 to 60 percent was demonstrated and verified with NDE methods. Steel foam integrated beams, cylinders and plates were mechanically tested and demonstrated advantages in bend stiffness, bend resistance, and crush energy absorption. Methods of joining by welding, adhesive bonding, and mechanical fastening were investigated. It is important to keep in mind that steel foam is a conventional material in an unconventional form. A substantial amount of physical and mechanical properties are presented throughout the report and in a properties database at the end of the report to support designer's in applying steel foam in unconventional ways.

  16. Optical Spectroscopy of Nano Materials and Structures

    Science.gov (United States)

    Guo, Wenhao

    In this thesis, nanostructures and nanomaterials ranging from 3D to OD will be studied compresively, by using optical methods. Firstly, for 3D and 2D nanomaterials, nanoporous zeolite crystals, such as AFI and AEL are introduced as host materials to accommodate diatomic iodine molecules. Polarized Raman spectroscopy is utilized to identify the two configurations of iodine molecules to stay in the channels of AEL: the lying mode (the bond of the two atoms is parallel to the direction of the channels) and the standing mode (the bond is perpendicular to the direction of the channels). The lying mode and standing mode are switchable and can be well controlled by the amount of water molecules inside the crystal, revealed by both molecule dynamics simulation and experiment observation. With more water molecules inside, iodine molecules choose to stay in the standing mode, while with less water molecules, iodine molecules prefer to lie along the channel. Therefore, the configurations of molecules could be precisely controlled, globally by the surrounding pressure and temperature, and locally by the laser light. Ii is believed that this easy and reversible control of single molecule will be valuable in nanostructured devices, such as molecular sieving or molecular detection. Secondly, for 1D case, the PL spectrum of ZnO nanowire under uniaxial strain is studied. When a ZnO nanowire is bent, besides the lattice constant induced bandgap change on the tensile and compressive sides, there is a piezoelectric field generated along the cross section. This piezoelectric potential, together with the bandgap changes induced by the deformation, will redistribute the electrons excited by incident photons from valence band to conduction band. As a result, the electrons occupying the states at the tensile side will largely outnumbered the ones at the compressive side. Therefore, the PL spectrum we collected at the whole cross section will manifest a redshift, other than the peak

  17. Fea04/PNIPAM纳米复合微球的制备%Preparation of Fe304/PNIPAM Nano-scale Composite-microspheres

    Institute of Scientific and Technical Information of China (English)

    温裕乾; 蔡力锋; 林志勇; 钱浩; 韩惠琴; 林现水

    2012-01-01

    Magnetic Fe304 nanoparticles were prepared by co-precipitation, and further encapsulated with poly(N-isopropylacrylamide) via seeded emulsion polymerization to form Fe3Oa/PNIPAM nano-scale composite-microspheres. The microspheres were characterized by FTIR, TEM, TGA and DTS. Herewith the effects of the concentration of monomer (NIPAM), cross-linker (MBA) and emulsifier (SDBS) on the diameter, magnetic Fe304 content of the microspheres were investigated. The reaction parameters show notable influence on the structure and morphology of the microspheres, and as a result, the diameter and magnetite content of the microspheres decreased with the decrease of monomer concentration and the increase of cross-linker concentration and emulsifier concentration.%用化学共沉淀法制备Fe304磁性纳米粒子,以N-异丙基丙烯酰胺(NIPAM)、N,N’-亚甲基双丙烯酰胺(MBA)和偶氮二异丁腈(AIBN)为原料,用种子乳液聚合法制备了具有温敏性的Fea04/PNIPAM纳米复合微球。用红外光谱仪(FTIR)、透射电镜(TEM)、热重分析仪(TGA)及Zeta粒度仪(DTS)等手段对复合微球进行了表征,研究了单体(NIPAM)、交联剂(MBA)、乳化剂(SDBS)用量对复合微球粒径及磁含量的影响。结果表明:Fea04/PNIPAM纳米复合微球呈球形,具有温敏性,反应条件对复合微球的结构和形貌有较为显著的影响,其粒径和磁含量随着单体浓度的减少、交联剂和乳化剂用量的增加而变小。

  18. Effect of nano-scaled styrene butadiene rubber based nucleating agent on the thermal, crystallization and physical properties of isotactic polypropylene

    Energy Technology Data Exchange (ETDEWEB)

    Petchwattana, Nawadon [Division of Polymer Materials Technology, Faculty of Agricultural Product Innovation and Technology, Srinakharinwirot University, Sukhumvit 23, Wattana, Bangkok 10110 (Thailand); Covavisaruch, Sirijutaratana, E-mail: sirijutaratana.c@chula.ac.th [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Pathumwan, Bangkok 10330 (Thailand); Sripanya, Panjapong [Thai Oleochemicals Company Limited (A Subsidiary of PTT Global Chemical Public Company Limited), Mueang Rayong, Rayong 21150 (Thailand)

    2014-01-05

    Highlights: • The effect of a SBR based β-NA on the properties iPP was investigated. • The addition of β-NA led to higher population of nuclei and smaller spherulites. • β to α phase transformation was observed when re-extrusion process was applied. • Impact strength was increased when the β-NA was added from 0.10 to 0.20 wt%. -- Abstract: The influence of a specific nano-scaled styrene butadiene rubber based β-nucleating agent (β-NA) on the properties of isotactic polypropylene (iPP) was investigated in the current research. β-NA was applied at the concentration ranged from 0.05 to 0.50 wt%. Microscopic observation revealed that the neat iPP crystals grew very slowly; they ranged in size from 100 to 200 μm. The addition of β-NA led to higher population of nuclei and smaller spherulites than those found in neat iPP. The addition of only 0.05 wt% β-NA significantly decreased the sizes of the spherulites down to 5 μm; the crystal grew very rapidly, leading to extremely fine morphology. Analysis by X-ray diffraction (XRD) confirmed that iPP/β-NA constituted mainly of β-crystal structure. The transformation of β to α phase was observed upon re-extrusion, it was verified by the lowered fraction of the β-crystalline phase (K{sub β}) although the total degree of crystallinity remained unchanged. A significant improvement in the impact strength of the iPP/β-NA was observed when the β-NA was employed from 0.10 to 0.20 wt%, leading to the formation of tough β-crystals in the β-NA nucleated iPP. The color measurement implied that the iPP nucleated with β-NA was superior in terms of whiteness but it was less transparent, as was evident by the increased haze.

  19. Course Modules on Structural Health Monitoring with Smart Materials

    Science.gov (United States)

    Shih, Hui-Ru; Walters, Wilbur L.; Zheng, Wei; Everett, Jessica

    2009-01-01

    Structural Health Monitoring (SHM) is an emerging technology that has multiple applications. SHM emerged from the wide field of smart structures, and it also encompasses disciplines such as structural dynamics, materials and structures, nondestructive testing, sensors and actuators, data acquisition, signal processing, and possibly much more. To…

  20. Fatigue Prediction for Composite Materials and Structures

    Science.gov (United States)

    2005-10-01

    Teoría de Mezclas Serie-Paralelo Avanzada para el Análisis de Materiales Compuestos ” V Congreso de la Asociacion Española de Materiales Compuestos ...Computational Materials Science 32, 175–195 [2] Rastellini, F.; Oller, S. (2004). Modelado numérico de no linealidad constitutiva en laminados compuestos

  1. Understanding structural conservation through materials science:

    DEFF Research Database (Denmark)

    Fuster-López, Laura; Krarup Andersen, Cecil

    2014-01-01

    with tools to avoid future problems, it should be present in all conservation-restoration training programs to help promote students’ understanding of the degradation mechanisms in cultural materials (and their correlation with chemical and biological degradation) as well as the implications behind...

  2. Materials for Adaptive Structural Acoustic Controls

    Science.gov (United States)

    1994-01-31

    found in ing atoms collapse systematically around ultrasonic motors . Electrooptic materials the small B ions. will become future key components in dis...electromechanical devices (piezoelectric ac- aries by thermal treatment so as to make tuators, ultrasonic motors ) the boundary layer highly-resistive

  3. SRM (Solid Rocket Motor) propellant and polymer materials structural modeling

    Science.gov (United States)

    Moore, Carleton J.

    1988-01-01

    The following investigation reviews and evaluates the use of stress relaxation test data for the structural analysis of Solid Rocket Motor (SRM) propellants and other polymer materials used for liners, insulators, inhibitors, and seals. The stress relaxation data is examined and a new mathematical structural model is proposed. This model has potentially wide application to structural analysis of polymer materials and other materials generally characterized as being made of viscoelastic materials. A dynamic modulus is derived from the new model for stress relaxation modulus and is compared to the old viscoelastic model and experimental data.

  4. Properties of structural materials in liquid metal environment. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Borgstedt, H.U. [ed.

    1991-12-15

    The International Working Group on Fast Reactors (IWGFR) Specialists Meeting on Properties of Structural Materials in Liquid Metal Environment was held during June 18 to June 20, 1991, at the Nuclear Research Centre (Kernforschungszentrum) in Karlsruhe, Germany. The Specialists Meeting was divided into five technical sessions which addressed topics as follows: Creep-Rupture Behaviour of Structural Materials in Liquid Metal Environment; Behaviour of Materials in Liquid Metal Environments under Off-Normal Conditions;Fatigue and Creep-Fatigue of Structural Materials in Liquid Metal Environment; Crack Propagation in Liquid Sodium; and Conclusions and recommendations. Individual papers have been cataloged separately.

  5. Information and computer-aided system for structural materials

    Energy Technology Data Exchange (ETDEWEB)

    Nekrashevitch, Yu.G.; Nizametdinov, Sh.U.; Polkovnikov, A.V.; Rumjantzev, V.P.; Surina, O.N. (Engineering Physics Inst., Moscow (Russia)); Kalinin, G.M.; Sidorenkov, A.V.; Strebkov, Yu.S. (Research and Development Inst. of Power Engineering, Moscow (Russia))

    1992-09-01

    An information and computer-aided system for structural materials data has been developed to provide data for the fusion and fission reactor system design. It is designed for designers, industrial engineers, and material science specialists and provides a friendly interface in an interactive mode. The database for structural materials contains the master files: Chemical composition, physical, mechanical, corrosion, technological properties, regulatory and technical documentation. The system is implemented on a PC/AT running the PS /2 operating system. (orig.).

  6. Graphene materials having randomly distributed two-dimensional structural defects

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Harold H.; Zhao, Xin; Hayner, Cary M.; Kung, Mayfair C.

    2016-05-31

    Graphene-based storage materials for high-power battery applications are provided. The storage materials are composed of vertical stacks of graphene sheets and have reduced resistance for Li ion transport. This reduced resistance is achieved by incorporating a random distribution of structural defects into the stacked graphene sheets, whereby the structural defects facilitate the diffusion of Li ions into the interior of the storage materials.

  7. Graphene materials having randomly distributed two-dimensional structural defects

    Science.gov (United States)

    Kung, Harold H; Zhao, Xin; Hayner, Cary M; Kung, Mayfair C

    2013-10-08

    Graphene-based storage materials for high-power battery applications are provided. The storage materials are composed of vertical stacks of graphene sheets and have reduced resistance for Li ion transport. This reduced resistance is achieved by incorporating a random distribution of structural defects into the stacked graphene sheets, whereby the structural defects facilitate the diffusion of Li ions into the interior of the storage materials.

  8. Structural materials for large superconducting magnets for tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Long, C.J.

    1976-12-01

    The selection of structural materials for large superconducting magnets for tokamak-type fusion reactors is considered. The important criteria are working stress, radiation resistance, electromagnetic interaction, and general feasibility. The most advantageous materials appear to be face-centered-cubic alloys in the Fe-Ni-Cr system, but high-modulus composites may be necessary where severe pulsed magnetic fields are present. Special-purpose structural materials are considered briefly.

  9. Development of Ultra-High Mechanical Damping Structures Based on the Nano-Scale Properties of Shape Memory Alloys

    Science.gov (United States)

    2013-07-29

    Condensada Facultad de Ciencia y Tecnologia Aptdo 644 Bilbao, Spain 48080 EOARD Grant 10-3074 Report Date: July 2013 Final Report... Ciencia y Tecnologia Aptdo 644 Bilbao, Spain 48080 8. PERFORMING ORGANIZATION REPORT NUMBER N/A 9. SPONSORING/MONITORING AGENCY... Ciencia y Tecnologia, Aptdo 644, 48080 Bilbao, Spain. E-mail: jose.sanjuan@ehu.es Summary In recent years it was discovered that micro and nano

  10. Development of Ultra-high Mechanical Damping Structures Based on Nano-scale Properties of Shape Memory Alloys

    Science.gov (United States)

    2011-07-27

    Alloys Jose San Juan Universidad del Pais Vasco Department of Physics of Condensed Matter Facultd de Ciencia y Tecnologia Bilbao...Facultd de Ciencia y Tecnologia Bilbao, Spain 48080 8. PERFORMING ORGANIZATION REPORT NUMBER N/A 9. SPONSORING/MONITORING AGENCY NAME(S

  11. Composite Materials and Sandwich Structures - A Primer

    Science.gov (United States)

    2010-05-01

    quality and protects prepreg from handling damage. Non - woven unidirectional tapes can otherwise split between fibers. Clean, white lint-free cotton ...applications and S glass fibers are used in strength critical situations. S glass fibers are sometimes woven in composite materials to increase toughness...A woven form of the reinforcements (Figure 1b) is also used in certain cases, depending on the application of the composite. Figure 1a- Fiber

  12. Research on Composite Materials for Structural Design.

    Science.gov (United States)

    1984-04-01

    Residual Stresses in Composite Laminates", (August 1983); the M.Sc. thesis of E.J. Porth , titled "Effect of an External Stress on Moisture Diffusion in...Rates in OUnidirectional Double Cantilevered Beam Fracture Toughness Specimens", December 1982. 4. Porth , E.J., "Effect of an External Stress on...Composite Materials (December 1983) Edward John Porth , B.S., University of Colorado Chairman of Advisory Committee: Dr. Y. Weitsman This work concerns

  13. Structural materials for the next generation of technologies

    CERN Document Server

    Van de Voorde, Marcel Hubert

    1996-01-01

    1. Overview of advanced technologies; i.e. aerospace-aeronautics; automobile; energy technology; accelerator engineering etc. and the need for new structural materials. 2. Familiarisation with polymers, metals and alloys, structural ceramics, composites and surface engineering. The study of modern materials processing, generation of a materials data base, engineering properties includind NDE, radiation damage etc. 3. Development of new materials for the next generation of technologies; including the spin-off of materials developed for space and military purposes to industrial applications. 4. Materials selection for modern accelerator engineering. 5. Materials research in Europe, USA and Japan. Material R & D programmes sponsored by the European Union and the collaboration of CERN in EU sponsored programmes.

  14. Lightweight Materials and Structures (LMS): Inflatable Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Inflatable Structures (InSTAR) project goal is to demonstrate long term durability of inflatable habitat structures for potential utilization as either in-space...

  15. Types of architectural structures and the use of smart materials

    Science.gov (United States)

    Tavşan, Cengiz; Sipahi, Serkan

    2017-07-01

    The developments in technology following the industrial revolution had their share of impact on both construction techniques, and material technologies. The change in the materials used by the construction industry brought along numerous innovations, which, in turn, took on an autonomous trend of development given the rise of nano-tech materials. Today, nano-tech materials are used extensively in numerous construction categories. Nano-tech materials, in general, are characterized by their reactionary nature, with the intent of repeating the reactions again and again under certain conditions. That is why nano-tech materials are often called smart materials. In construction industry, smart materials are categorized under 4 major perspectives: Shape-shifting smart materials, power generating smart materials, self-maintenance smart materials, and smart materials providing a high level of insulation. In architecture, various categories of construction often tend to exhibit their own approaches to design, materials, and construction techniques. This is a direct consequence of the need for different solutions for different functions. In this context, the use of technological materials should lead to the use of a set of smart materials for a given category of structures, while another category utilizes yet another set. In the present study, the smart materials used in specific categories of structures were reviewed with reference to nano-tech practices implemented in Europe, with a view to try and reveal the changes in the use of smart materials with reference to categories of structures. The study entails a discussion to test the hypothesis that nano-tech materials vary with reference to structure categories, on the basis of 18 examples from various structure categories, built by the construction firms with the highest level of potential in terms of doing business in Europe. The study comprises 3 major sections: The first section reiterates what the literature has to say

  16. Smart Materials in Structural Health Monitoring, Control and Biomechanics

    CERN Document Server

    Soh, Chee-Kiong; Bhalla, Suresh

    2012-01-01

    "Smart Materials in Structural Health Monitoring, Control and Biomechanics" presents the latest developments in structural health monitoring, vibration control and biomechanics using smart materials. The book mainly focuses on piezoelectric, fibre optic and ionic polymer metal composite materials. It introduces concepts from the very basics and leads to advanced modelling (analytical/ numerical), practical aspects (including software/ hardware issues) and case studies spanning civil, mechanical and aerospace structures, including bridges, rocks and underground structures. This book is intended for practicing engineers, researchers from academic and R&D institutions and postgraduate students in the fields of smart materials and structures, structural health monitoring, vibration control and biomedical engineering. Professor Chee-Kiong Soh and Associate Professor Yaowen Yang both work at the School of Civil and Environmental Engineering, Nanyang Technological University, Singapore. Dr. Suresh Bhalla is an A...

  17. Anisotropy and optical gain improvement in type-II In0.3Ga0.7As/GaAs0.4Sb0.6 nano-scale heterostructure under external uniaxial strain

    Science.gov (United States)

    Singh, A. K.; Riyaj, Md.; Anjum, S. G.; Yadav, Nisha; Rathi, Amit; Siddiqui, M. J.; Alvi, P. A.

    2016-10-01

    Alterations in optical transitions and distortions in wave symmetry in nano-scale QW (quantum well) heterostructures are seen due to external uniaxial strain under different polarizations. This paper reports the anisotropy phenomena and optical gain improvement realized in In0.3Ga0.7As/GaAs0.4Sb0.6 type-II QW-heterostructure (well width = 20 Å) under uniaxial strain in the SWIR (short wave infra red) region. The detailed study of the band structure, wave functions associated with the charge carriers in the respective bands and optical gain under electromagnetic field perturbation is reported. The 6 × 6 diagonal k → ·p → Hamiltonian matrix is evaluated and Luttinger-Kohn model is used for the band structure calculation. Optical gain spectrum in the QW-heterostructure under uniaxial strain along [110] for different polarizations of light is calculated. For a charge carrier injection of 5 × 1012/cm2 the optical gain is ∼1600/cm under input z-polarization, ∼14500/cm under x-polarization and ∼15700/cm under y-polarization without external uniaxial strain applied. A significant improvement in optical gain is observed under uniaxial strain along [110] direction under different input polarizations. Keeping in views its utilization in optoelectronics due its very high optical gain in near-infra-red region in x- or y-polarization mode, such structure can be considered as a novel structure.

  18. Modeling Polymer Stabilized Nano-scale Zero Valent Iron Transport Experiments in Porous Media to Understand the Transport Behavior

    Science.gov (United States)

    Mondal, P.; Krol, M.; Sleep, B. E.

    2015-12-01

    A wide variety of groundwater contaminants can be treated with nano-scale zero valent iron (nZVI). However, delivery of nZVI in the subsurface to the treatment zones is challenging as the bare nZVI particles have a higher tendency to agglomerate. The subsurface mobility of nZVI can be enhanced by stabilizing nZVI with polymer, such as carboxymethyl cellulose (CMC). In this study, numerical simulations were conducted to evaluate CMC stabilized nZVI transport behavior in porous media. The numerical simulations were based on a set of laboratory-scale transport experiments that were conducted in a two-dimensional water-saturated glass-walled sandbox (length - 55 cm; height - 45 cm; width - 1.4 cm), uniformly packed with silica sand. In the transport experiments: CMC stabilized nZVI and a non-reactive dye tracer Lissamine Green B (LGB) were used; water specific discharge and CMC concentration were varied; movements of LGB, and CMC-nZVI in the sandbox were tracked using a camera, a light source and a dark box. The concentrations of LGB, CMC, and CMC-nZVI at the sandbox outlet were analyzed. A 2D multiphase flow and transport model was applied to simulate experimental results. The images from LGB dye transport experiments were used to determine the pore water velocities and media permeabilities in various layers in the sand box. These permeability values were used in the subsequent simulations of CMC-nZVI transport. The 2D compositional simulator, modified to include colloid filtration theory (CFT), treated CMC as a solute and nZVI as a colloid. The simulator included composition dependent viscosity to account for CMC injection and mixing, and attachment efficiency as a fitting parameter for nZVI transport modeling. In the experiments, LGB and CMC recoveries were greater than 95%; however, CMC residence time was significantly higher than the LGB residence time and the higher CMC concentration caused higher pressure drops in the sandbox. The nZVI recovery was lower than 40

  19. Micro-and nano-structured conducting polymeric materials

    Institute of Scientific and Technical Information of China (English)

    LU Gewu; CHEN Feng'en; WU Xufeng; QU Liangti; ZHANG Jiaxin; SHI Gaoquan

    2005-01-01

    Conducting polymeric materials with micro-/nano-structures have potential applications in fabrication of various optical, electronic, sensing and electrochemical devices. This is mainly because these materials not only possess the characteristics of conducting polymers, but also have special functions based on their micro- or nano-structures. In this review, we summarize the recent work on "soft" and "hard" template-guided syntheses of micro-/nano-structured conducting polymers and open up the prospects of the main trends in this field.

  20. Design of Spintronic Materials with Simple Structures

    Energy Technology Data Exchange (ETDEWEB)

    Fong, C Y; Qian, M C; Liu, K; Yang, L H; Pask, J E

    2007-05-03

    A brief comparison of conventional electronics and spintronics is given. The key features of half metallic binary compounds with the zincblende structure are presented, using MnAs as an example. We discuss the interactions responsible for the half metallic properties. Special properties of superlattices and a digital ferromagnetic heterostructure incorporating zincblende half metals are also discussed.

  1. Manufacture of Nano Structures in Polymer Material

    DEFF Research Database (Denmark)

    Hansen, Hans Nørgaard; Pedersen, H.C.; Staun, Jacob

    2003-01-01

    components are to be used in a microsystem, subsequent handling and assembly is necessary. The present paper describes the process chain related to the manufacture of optical gratings with nanometer-sized structures. The problems of each process step and the challenges of establishing a coherent production...

  2. NONLINEAR BUCKLING CHARACTERISTIC OF GRADED MULTIWEB STRUCTURE OF HETEROGENEOUS MATERIALS

    Institute of Scientific and Technical Information of China (English)

    LI Yong; ZHANG Zhi-min

    2005-01-01

    The graded multiweb structure of heterogeneous anisotropic materials, which makes full use of the continuous, gradual and changing physical mechanical performance of material properties, has a widespread application in aeroplane aerofoil structure and automobile lightweight structure. On the basis of laminate buckling theory,the equivalent rigidity method is adopted to establish the corresponding constitutive relation and the non-linear buckling governing equation for the graded multiweb structure. In finding the solution, the critical load of buckling under different complicated boundary conditions together with combined loads were obtained and testification of the experimental analysis shows that the calculation results can satisfy the requirements of engineering design in a satisfactory way. Results obtained from the research say that: graded materials can reduce the concentrated stress on the interface in an effective way and weaken the effect of initial defect in materials and thereby improve the strength and toughness of materials.

  3. Surface structure and electronic properties of materials

    Science.gov (United States)

    Siekhaus, W. J.; Somorjai, G. A.

    1975-01-01

    A surface potential model is developed to explain dopant effects on chemical vapor deposition. Auger analysis of the interaction between allotropic forms of carbon and silicon films has shown Si-C formation for all forms by glassy carbon. LEED intensity measurements have been used to determine the mean square displacement of surface atoms of silicon single crystals, and electron loss spectroscopy has shown the effect of structure and impurities on surface states located within the band gap. A thin film of Al has been used to enhance film crystallinity at low temperature.

  4. Neutron Scattering Studies of Nanomagnetism and Artificially Structured Materials

    Energy Technology Data Exchange (ETDEWEB)

    Fitzsimmons, M.R.; Bader, S.D.; Borchers, J.A.; Felcher, G.P.; Furdyna, J.K.; Hoffmann, A.; Kortright, J.B.; Schuller, Ivan K.; Schulthess, T.C.; Sinha, S.K.; Toney, M.F.; Weller, D.; Wolf, S.

    2003-02-01

    Nanostructured magnetic materials are intensively studied due to their unusual properties and promise for possible applications. The key issues in these materials relate to the connection between their physical properties (transport, magnetism, mechanical, etc.) and their chemical-physical structure. In principle, a detailed knowledge of the chemical and physical structure allows calculation of their physical properties. Theoretical and computational methods are rapidly evolving so that magnetic properties of nanostructured materials might soon be predicted. Success in this endeavor requires detailed quantitative understanding of the magnetic structure and properties.

  5. In-situ nano-crystal-to-crystal transformation synthesis of energetic materials based on three 5,5′-azotetrazolate Cr(III) salts

    Science.gov (United States)

    Miao, Yu; Qiu, Yanxuan; Cai, Jiawei; Wang, Zizhou; Yu, Xinwei; Dong, Wen

    2016-01-01

    The in-situ nano-crystal-to-crystal transformation (SCCT) synthesis provides a powerful approach for tailoring controllable feature shapes and sizes of nano crystals. In this work, three nitrogen-rich energetic nano-crystals based on 5,5′-azotetrazolate(AZT2−) Cr(III) salts were synthesized by means of SCCT methodology. SEM and TEM analyses show that the energetic nano-crystals feature a composition- and structure-dependent together with size-dependent thermal stability. Moreover, nano-scale decomposition products can be obtained above 500 °C, providing a new method for preparing metallic oxide nano materials. PMID:27869221

  6. In-situ nano-crystal-to-crystal transformation synthesis of energetic materials based on three 5,5'-azotetrazolate Cr(III) salts.

    Science.gov (United States)

    Miao, Yu; Qiu, Yanxuan; Cai, Jiawei; Wang, Zizhou; Yu, Xinwei; Dong, Wen

    2016-11-21

    The in-situ nano-crystal-to-crystal transformation (SCCT) synthesis provides a powerful approach for tailoring controllable feature shapes and sizes of nano crystals. In this work, three nitrogen-rich energetic nano-crystals based on 5,5'-azotetrazolate(AZT(2-)) Cr(III) salts were synthesized by means of SCCT methodology. SEM and TEM analyses show that the energetic nano-crystals feature a composition- and structure-dependent together with size-dependent thermal stability. Moreover, nano-scale decomposition products can be obtained above 500 °C, providing a new method for preparing metallic oxide nano materials.

  7. Assessment of nano-scale Stirling refrigerator using working fluid as Maxwell-Boltzmann gases by thermo-ecological and sustainability criteria

    Science.gov (United States)

    Açıkkalp, Emin; Savaş, Ahmet Fevzi; Caner, Necmettin; Yamık, Hasan

    2016-08-01

    Purpose of this paper is to investigate a nano scale irreversible Stirling refrigerator regarding size effects and presents one novel thermo-ecological criteria. System is researched by using four thermo-ecological and sustainable criteria. One novel criteria called modified ecological coefficient of performance (MECOP) is presented. Calculations are performed for irreversible cycle and results are obtained numerically. Finally, performance of the considered cycle is discussed and regarded criteria are compared. According to results, ESI is the most stable ecological criteria and MECOP is more stable than ECOP and x should be chosen as big as possible.

  8. Plasmonic Structural Colors for Plastic Consumer Products

    DEFF Research Database (Denmark)

    Højlund-Nielsen, Emil; Mortensen, N. Asger; Kristensen, Anders

    2014-01-01

    Today colorants, such as pigments or dyes, are used to color plastic-based consumer products, either as base for solid colored bulk polymer or in inks for surface decoration. After usage, the products must be mechanically sorted by color before recycling, limiting any large-scale efficient...... recycling effort. As an alternative to chemistry-based coloring, nano-scale structural coloring has been proposed to reduce the number of materials needed and to increase pattern resolution. Here colors are created by structural based light-matter interactions in the surface. Thereby, the sorting by color...... can be avoided in the recycling state. Plasmon color technology based on aluminum has recently been firmly established as a route towards structural coloring of polymeric materials. We report on the fabrication of colors by localized surface plasmon resonances (LSPR) using roll-to-roll printing...

  9. Composite materials applied to the E-ELT structure

    Science.gov (United States)

    Pajuelo, Eugenio; Gómez, José Ramón; Ronquillo, Bernardo; Brunetto, Enzo; Koch, Fran

    2008-07-01

    The upper part of the European Extremely Large Telescope (E-ELT) altitude structure is one of the most critical areas of the telescope's structure. This part hosts sensitive optical elements of the telescope. Its structural performance has a major impact on the whole system. The most critical requirements are low optical path obscuration, high static and dynamic performance (high specific modulus), high mechanical safety (high specific strength), low wind cross section and low weight. Composite materials are ideally suited to meet these requirements. This study is carried out in order to quantify the relative advantage of composite material over mild steel, in terms of performance and costs. The mechanical behavior of the steel structure can be easily improved with a structure manufactured with composite materials. This structure is significantly lighter than the steel one and reduces relative displacements between primary and secondary mirror. Consequently, optical performance is improved, assembly process is simplified and transport cost is reduced.

  10. Structural materials issues for the next generation fission reactors

    Science.gov (United States)

    Chant, I.; Murty, K. L.

    2010-09-01

    Generation-IV reactor design concepts envisioned thus far cater to a common goal of providing safer, longer lasting, proliferation-resistant, and economically viable nuclear power plants. The foremost consideration in the successful development and deployment of Gen-W reactor systems is the performance and reliability issues involving structural materials for both in-core and out-of-core applications. The structural materials need to endure much higher temperatures, higher neutron doses, and extremely corrosive environments, which are beyond the experience of the current nuclear power plants. Materials under active consideration for use in different reactor components include various ferritic/martensitic steels, austenitic stainless steels, nickel-base superalloys, ceramics, composites, etc. This article addresses the material requirements for these advanced fission reactor types, specifically addressing structural materials issues depending on the specific application areas.

  11. 7th ECCOMAS Thematic Conference on Smart Structures and Materials

    CERN Document Server

    Soares, Carlos

    2017-01-01

    This work was compiled with expanded and reviewed contributions from the 7th ECCOMAS Thematic Conference on Smart Structures and Materials, that was held from 3 to 6 June 2015 at Ponta Delgada, Azores, Portugal. The Conference provided a comprehensive forum for discussing the current state of the art in the field as well as generating inspiration for future ideas specifically on a multidisciplinary level. The scope of the Conference included topics related to the following areas: Fundamentals of smart materials and structures; Modeling/formulation and characterization of smart actuators, sensors and smart material systems; Trends and developments in diverse areas such as material science including composite materials, intelligent hydrogels, interfacial phenomena, phase boundaries and boundary layers of phase boundaries, control, micro- and nano-systems, electronics, etc. to be considered for smart systems; Comparative evaluation of different smart actuators and sensors; Analysis of structural concepts and des...

  12. Low Cost, Lightweight, Multifunctional Structural Shielding Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR involves the development of a lightweight innovative material for use as structure and radiation shielding in one. APS has assembled a uniquely qualified...

  13. Application of Advanced Radiation Shielding Materials to Inflatable Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This innovation is a weight-optimized, inflatable structure that incorporates radiation shielding materials into its construction, for use as a habitation module or...

  14. Classic and New Materials Used for Structural Rehabilitation. Case Study

    Science.gov (United States)

    Lute, M.

    2016-06-01

    New materials development with different combination of properties were always a challenge in terms of their adequate use in civil engineering. Introduction of carbon fibres as strength material for structures was a beginning of a new approach in structural rehabilitation, and sometimes meant the end of classic rehabilitation solution use. The present paper gives an example of a building rehabilitation that use a melt of both new and old solutions in order to achieve the optimum result for building itself. The problem was even more challenging, because the structure considered is only 22 years old, but having some design faults in terms of seismic behaviour and, in addition, one floor was added to existing structure. The chosen solution was a compromise between the use of old and new materials in places where their qualities were best suitable and their minuses could be compensated by the other material.

  15. Research on applications of piezoelectric materials in smart structures

    Science.gov (United States)

    Qiu, Jinhao; Ji, Hongli

    2011-03-01

    Piezoelectric materials have become the most attractive functional materials for sensors and actuators in smart structures because they can directly convert mechanical energy to electrical energy and vise versa. They have excellent electromechanical coupling characteristics and excellent frequency response. In this article, some research activities on the applications of piezoelectric materials in smart structures, including semi-active vibration control based on synchronized switch damping using negative capacitance, energy harvesting using new electronic interfaces, structural health monitoring based on a new type of piezoelectric fibers with metal core, and active hysteresis control based on new modified Prandtl-Ishlinskii model at the Aeronautical Science Key Laboratory for Smart Materials and Structures, Nanjing University of Aeronautics and Astronautics are introduced.

  16. Mesoscopic hydrothermodynamics of complex-structured materials

    Science.gov (United States)

    Vasconcellos, Áurea R.; Silva, A. A. P.; Luzzi, Roberto; Casas-Vázquez, J.; Jou, David

    2013-10-01

    Some experimental results in the study of disordered systems, polymeric fluids, solutions of micelles and surfactants, ionic-glass conductors, and others show a hydrodynamic behavior labeled “anomalous” with properties described by some kind of fractional power laws in place of the standard ones. This is a consequence of the fractal-like structure that is present in these systems of which we do not have a detailed description, thus impairing the application of the conventional ensemble formalism of statistical mechanics. In order to obtain a physical picture of the phenomenon for making predictions which may help with technological and industrial decisions, one may resort to different styles (so-called nonconventional) in statistical mechanics. In that way can be introduced a theory for handling such impaired situations, a nonconventional mesoscopic hydrothermodynamics (MHT). We illustrate the question presenting an application in a contracted description of such nonconventional MHT, consisting in the use of the Renyi approach to derive a set of coupled nonstandard evolution equations, one for the density, a nonconventional Maxwell-Cattaneo equation, which in a limiting case goes over a non-Fickian diffusion equation, and other for the velocity in fluids under forced flow. For illustration the theory is applied to the study of the hydrodynamic motion in several soft-matter systems under several conditions such as streaming flow appearing in electrophoretic techniques and flow generated by harmonic forces arising in optical traps. The equivalence with Lévy processes is discussed and comparison with experiment is done.

  17. Tunable structural color in organisms and photonic materials for design of bioinspired materials

    Directory of Open Access Journals (Sweden)

    Hiroshi Fudouzi

    2011-01-01

    Full Text Available In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites.

  18. Tunable structural color in organisms and photonic materials for design of bioinspired materials.

    Science.gov (United States)

    Fudouzi, Hiroshi

    2011-12-01

    In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites.

  19. Material design and structural color inspired by biomimetic approach

    Directory of Open Access Journals (Sweden)

    Akira Saito

    2011-01-01

    Full Text Available Generation of structural color is one of the essential functions realized by living organisms, and its industrial reproduction can result in numerous applications. From this viewpoint, the mechanisms, materials, analytical methods and fabrication technologies of the structural color are reviewed in this paper. In particular, the basic principles of natural photonic materials, the ideas developed from these principles, the directions of applications and practical industrial realizations are presented by summarizing the recent research results.

  20. Material design and structural color inspired by biomimetic approach.

    Science.gov (United States)

    Saito, Akira

    2011-12-01

    Generation of structural color is one of the essential functions realized by living organisms, and its industrial reproduction can result in numerous applications. From this viewpoint, the mechanisms, materials, analytical methods and fabrication technologies of the structural color are reviewed in this paper. In particular, the basic principles of natural photonic materials, the ideas developed from these principles, the directions of applications and practical industrial realizations are presented by summarizing the recent research results.

  1. Extended propagation model for interfacial crack in composite material structure

    Institute of Scientific and Technical Information of China (English)

    闫相桥; 冯希金

    2002-01-01

    An interfacial crack is a common damage in a composite material structure . An extended propaga-tion model has been established for an interfacial crack to study the dependence of crack growth on the relativesizes of energy release rates at left and right crack tips and the properties of interfacial material characterize thegrowth of interfacial crack better.

  2. Simultaneous dynamic electrical and structural measurements of functional materials

    Energy Technology Data Exchange (ETDEWEB)

    Vecchini, C.; Stewart, M.; Muñiz-Piniella, A.; Wooldridge, J. [National Physical Laboratory, Hampton Road, Teddington TW11 0LW (United Kingdom); Thompson, P.; McMitchell, S. R. C.; Bouchenoire, L.; Brown, S.; Wermeille, D.; Lucas, C. A. [XMaS, The UK-CRG, ESRF-The European Synchrotron, CS40220, F-38043, Grenoble Cedex 09 (France); Department of Physics, University of Liverpool, Liverpool L69 3BX (United Kingdom); Lepadatu, S. [National Physical Laboratory, Hampton Road, Teddington TW11 0LW (United Kingdom); Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom); Bikondoa, O.; Hase, T. P. A. [XMaS, The UK-CRG, ESRF-The European Synchrotron, CS40220, F-38043, Grenoble Cedex 09 (France); Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Lesourd, M. [ESRF-The European Synchrotron, CS40220, F-38043, Grenoble Cedex 09 (France); Dontsov, D. [SIOS Meßtechnik GmbH, Am Vogelherd 46, 98693 Ilmenau (Germany); Cain, M. G. [National Physical Laboratory, Hampton Road, Teddington TW11 0LW (United Kingdom); Electrosciences Ltd., Farnham, Surrey GU9 9QT (United Kingdom)

    2015-10-15

    A new materials characterization system developed at the XMaS beamline, located at the European Synchrotron Radiation Facility in France, is presented. We show that this new capability allows to measure the atomic structural evolution (crystallography) of piezoelectric materials whilst simultaneously measuring the overall strain characteristics and electrical response to dynamically (ac) applied external stimuli.

  3. Analysis and Design of Biological Materials and Structures

    CERN Document Server

    Öchsner, Andreas; Altenbach, Holm

    2012-01-01

    This collection provides researchers and scientists with advanced analyses and materials design techniques in Biomaterials and presents mechanical studies of biological structures. In 16 contributions well known experts present their research on Stress and Strain Analysis, Material Properties, Fluid and Gas mechanics and they show related problems.

  4. Structural parameter effect of porous material on sound absorption performance of double-resonance material

    Science.gov (United States)

    Fan, C.; Tian, Y.; Wang, Z. Q.; Nie, J. K.; Wang, G. K.; Liu, X. S.

    2017-06-01

    In view of the noise feature and service environment of urban power substations, this paper explores the idea of compound impedance, fills some porous sound-absorption material in the first resonance cavity of the double-resonance sound-absorption material, and designs a new-type of composite acoustic board. We conduct some acoustic characterizations according to the standard test of impedance tube, and research on the influence of assembly order, the thickness and area density of the filling material, and back cavity on material sound-absorption performance. The results show that the new-type of acoustic board consisting of aluminum fibrous material as inner structure, micro-porous board as outer structure, and polyester-filled space between them, has good sound-absorption performance for low frequency and full frequency noise. When the thickness, area density of filling material and thickness of back cavity increase, the sound absorption coefficient curve peak will move toward low frequency.

  5. FIRE PROTECTION OF TIMBER STRUCTURES STRENGTHENED WITH FRP MATERIALS

    Directory of Open Access Journals (Sweden)

    Radek Zigler

    2015-12-01

    Full Text Available Modern, progressive methods of structures’ strengthening based on the use of composite materials composed of high strength fibers (carbon, glass, aramid or basalt and matrices based on epoxy resins brings, among many indisputable advantages (low weight, high effectiveness, easy application etc. also some disadvantages. One of the major disadvantages is a low fire resistance of these materials due to the low glass transition temperature Tg of the resin used. Based on an extensive research of strengthening of historic structures with FRP materials [1], the article outlines possible approaches to this problem, especially while strengthening timber load- bearing structures of historic buildings.

  6. Recent developments of discrete material optimization of laminated composite structures

    DEFF Research Database (Denmark)

    Lund, Erik; Sørensen, Rene

    2015-01-01

    This work will give a quick summary of recent developments of the Discrete Material Optimization approach for structural optimization of laminated composite structures. This approach can be seen as a multi-material topology optimization approach for selecting the best ply material and number....... The different interpolation schemes used are described, and it is briefly outlined how design rules/manufacturing constraints can be included in the optimization. The approach has been demonstrated for a number of global design criteria like mass, compliance, buckling load factors, etc., but recent work makes...

  7. Time-Dependent Measure of a Nano-Scale Force-Pulse Driven by the Axonemal Dynein Motors in Individual Live Sperm Cells

    Energy Technology Data Exchange (ETDEWEB)

    Allen, M J; Rudd, R E; McElfresh, M W; Balhorn, R

    2009-04-23

    Nano-scale mechanical forces generated by motor proteins are crucial to normal cellular and organismal functioning. The ability to measure and exploit such forces would be important to developing motile biomimetic nanodevices powered by biological motors for Nanomedicine. Axonemal dynein motors positioned inside the sperm flagellum drive microtubule sliding giving rise to rhythmic beating of the flagellum. This force-generating action makes it possible for the sperm cell to move through viscous media. Here we report new nano-scale information on how the propulsive force is generated by the sperm flagellum and how this force varies over time. Single cell recordings reveal discrete {approx}50 ms pulses oscillating with amplitude 9.8 {+-} 2.6 nN independent of pulse frequency (3.5-19.5 Hz). The average work carried out by each cell is 4.6 x 10{sup -16} J per pulse, equivalent to the hydrolysis of {approx}5,500 ATP molecules. The mechanochemical coupling at each active dynein head is {approx}2.2 pN/ATP, and {approx}3.9 pN per dynein arm, in agreement with previously published values obtained using different methods.

  8. Topology optimization of coated structures and material interface problems

    DEFF Research Database (Denmark)

    Clausen, Anders; Aage, Niels; Sigmund, Ole

    2015-01-01

    This paper presents a novel method for including coated structures and prescribed material interface properties into the minimum compliance topology optimization problem. Several elements of the method are applicable to a broader range of interface problems. The approach extends the standard SIMP...... method by including the normalized norm of the spatial gradient of the design field into the material interpolation function, enforcing coating material at interfaces by attributing particular properties. The length scales of the base structure and the coating are separated by introducing a two......-step filtering/projection approach. The modeled coating thickness is derived analytically, and the coating is shown to be accurately controlled and applied in a highly uniform manner over the structure. An alternative interpretation of the model is to perform single-material design for additive manufacturing...

  9. Topology optimization of coated structures and material interface problems

    DEFF Research Database (Denmark)

    Clausen, Anders; Aage, Niels; Sigmund, Ole

    2015-01-01

    This paper presents a novel method for including coated structures and prescribed material interface properties into the minimum compliance topology optimization problem. Several elements of the method are applicable to a broader range of interface problems. The approach extends the standard SIMP...... method by including the normalized norm of the spatial gradient of the design field into the material interpolation function, enforcing coating material at interfaces by attributing particular properties. The length scales of the base structure and the coating are separated by introducing a two......-step filtering/projection approach. The modeled coating thickness is derived analytically, and the coating is shown to be accurately controlled and applied in a highly uniform manner over the structure. An alternative interpretation of the model is to perform single-material design for additive manufacturing...

  10. 3D Images of Materials Structures Processing and Analysis

    CERN Document Server

    Ohser, Joachim

    2009-01-01

    Taking and analyzing images of materials' microstructures is essential for quality control, choice and design of all kind of products. Today, the standard method still is to analyze 2D microscopy images. But, insight into the 3D geometry of the microstructure of materials and measuring its characteristics become more and more prerequisites in order to choose and design advanced materials according to desired product properties. This first book on processing and analysis of 3D images of materials structures describes how to develop and apply efficient and versatile tools for geometric analysis

  11. Composite Structures and Materials Research at NASA Langley Research Center

    Science.gov (United States)

    Starnes, James H., Jr.; Dexter, H. Benson; Johnston, Norman J.; Ambur, Damodar R.; Cano, roberto J.

    2003-01-01

    A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI), Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.

  12. Untethered micro-robotic coding of three-dimensional material composition

    Science.gov (United States)

    Tasoglu, S.; Diller, E.; Guven, S.; Sitti, M.; Demirci, U.

    2014-01-01

    Complex functional materials with three-dimensional micro- or nano-scale dynamic compositional features are prevalent in nature. However, the generation of three-dimensional functional materials composed of both soft and rigid microstructures, each programmed by shape and composition, is still an unsolved challenge. Here we describe a method to code complex materials in three-dimensions with tunable structural, morphological and chemical features using an untethered magnetic micro-robot remotely controlled by magnetic fields. This strategy allows the micro-robot to be introduced to arbitrary microfluidic environments for remote two- and three-dimensional manipulation. We demonstrate the coding of soft hydrogels, rigid copper bars, polystyrene beads and silicon chiplets into three-dimensional heterogeneous structures. We also use coded microstructures for bottom-up tissue engineering by generating cell-encapsulating constructs.

  13. Point Defect Phenomena of Crystalline Structure in Some Common Structural Materials

    Institute of Scientific and Technical Information of China (English)

    RUAN Yu-Zhong; WU Ren-Ping; YU Yan

    2005-01-01

    The existence and its movement rule of crystalline structure defect are closely related to the diffusion, solid phase reaction, sintering, phase transformation as well as the physical and chemical properties of materials. Point defect theory has been widely applied in material mineralization research, unfavorable transformation controlling, material modification,the research and development of new materials and so on. Point defect theory is one of the important theories for new material research and development. Herein we mainly discuss the application of point defect theory in some structural material researches.

  14. Computational methods to determine the structure of hydrogen storage materials

    Science.gov (United States)

    Mueller, Tim

    2009-03-01

    To understand the mechanisms and thermodynamics of material-based hydrogen storage, it is important to know the structure of the material and the positions of the hydrogen atoms within the material. Because hydrogen can be difficult to resolve experimentally computational research has proven to be a valuable tool to address these problems. We discuss different computational methods for identifying the structure of hydrogen materials and the positions of hydrogen atoms, and we illustrate the methods with specific examples. Through the use of ab-initio molecular dynamics, we identify molecular hydrogen binding sites in the metal-organic framework commonly known as MOF-5 [1]. We present a method to identify the positions of atomic hydrogen in imide structures using a novel type of effective Hamiltonian. We apply this new method to lithium imide (Li2NH), a potentially important hydrogen storage material, and demonstrate that it predicts a new ground state structure [2]. We also present the results of a recent computational study of the room-temperature structure of lithium imide in which we suggest a new structure that reconciles the differences between previous experimental and theoretical studies. [4pt] [1] T. Mueller and G. Ceder, Journal of Physical Chemistry B 109, 17974 (2005). [0pt] [2] T. Mueller and G. Ceder, Physical Review B 74 (2006).

  15. Layer Structured Materials for Advanced Energy Storage and Conversion.

    Science.gov (United States)

    Guo, Yanpeng; Wei, Yaqing; Li, Huiqiao; Zhai, Tianyou

    2017-09-13

    Owing to the strong in-plane chemical bonds and weak van der Waals force between adjacent layers, investigations of layer structured materials have long been the hotspots in energy-related fields. The intrinsic large interlayer space endows them capabilities of guest ion intercalation, fast ion diffusion, and swift charge transfer along the channels. Meanwhile, the well-maintained in-plane integrity contributes to exceptional mechanical properties. This anisotropic structural feature is also conducive to effective chemical combination, exfoliation, or self-assembly into various nanoarchitectures, accompanied by the introduction of defects, lattice strains, and phase transformation. This review starts with a brief introduction of typical layered materials and their crystal structures, then the structural characteristics and structure oriented unique applications in batteries, capacitors, catalysis, flexible devices, etc., are highlighted. It is surprising to observe that layered materials possess: (1) high reactivity, high reversibility, and enhanced performance via forming additional chemical bonds in alkali-metal ion batteries; (2) facile phase modulation, great feasibility for in-plane/sandwich device design, and cation intercalation enabled high capacitance in supercapacitors; (3) promoted structural diversity, effective strain engineering, and capabilities to function as ideal supporting materials/templates in electrocatalysis field. Finally, the future prospects and challenges faced by layered materials are also outlined. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. NASA Subsonic Rotary Wing Project - Structures and Materials Discipline

    Science.gov (United States)

    Halbig, Michael C.; Johnson, Susan M.

    2008-01-01

    The Structures & Materials Discipline within the NASA Subsonic Rotary Wing Project is focused on developing rotorcraft technologies. The technologies being developed are within the task areas of: 5.1.1 Life Prediction Methods for Engine Structures & Components 5.1.2 Erosion Resistant Coatings for Improved Turbine Blade Life 5.2.1 Crashworthiness 5.2.2 Methods for Prediction of Fatigue Damage & Self Healing 5.3.1 Propulsion High Temperature Materials 5.3.2 Lightweight Structures and Noise Integration The presentation will discuss rotorcraft specific technical challenges and needs as well as details of the work being conducted in the six task areas.

  17. Basic reactions of osteoblasts on structured material surfaces

    Directory of Open Access Journals (Sweden)

    B�chter A.

    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 osteoblastlike 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.

  18. Measurement Methods of Micro-structure of Porous Materials

    Directory of Open Access Journals (Sweden)

    Xingli Jiao

    2015-07-01

    Full Text Available Porous media is used in many areas of applied science and engineering and its characterization of porosity and micro-structure is very important, therefore, it is very necessary to know the measurements of pore structure of porous materials. In this study, some traditional methods that are used to measure micro-structure of porous material were briefly introduced in this study, including mercury porosimetry method, gas adsorption method, electronic microscope method, small angle X-ray scattering method and bubbling test method, followed by some emerging technology, including the combination of different methods, medical imaging technology and image processing software. Meanwhile merits and drawbacks as well as the existing problems of methods mentioned were analyzed and application range was described. At last, the developing trends and prospect of newly emerging methods, which is used to measure micro-structure of porous material, are also described briefly.

  19. Materials for Alternative Energies: Computational Materials Discovery and Crystal Structure Prediction

    Science.gov (United States)

    Wolverton, Chris

    2013-03-01

    Many of the key technological problems associated with alternative energies may be traced back to the lack of suitable materials. The materials discovery process may be greatly aided by the use of computational methods, particular those atomistic methods based on density functional theory. In this talk, we present an overview of recent work on energy-related materials from density-functional based approaches. We have developed novel computational tools which enable accurate prediction of crystal structures for new materials (using both Monte Carlo and Genetic Algorithm based approaches), materials discovery via high-throughput, data mining techniques, and automated phase diagram calculations. We highlight applications in the area of Li battery materials and hydrogen storage materials.

  20. Materializing a responsive interior: designing minimum energy structures

    DEFF Research Database (Denmark)

    Mossé, Aurélie; Kofod, Guggi; Ramsgaard Thomsen, Mette

    2011-01-01

    This paper discusses a series of design-led experiments investigating future possibilities for architectural materialization relying on minimum energy structures as an example of adaptive structure. The structures have been made as laminates of elastic membrane under high tension with flexible......-active structures based on dielectric-elastomer, where energy-minimization and self-organization principles become central processes for the realization of shape-changing architectural surfaces. In Reef, a concept for self-actuated ceiling surface, we examine the integration of these dynamic structures...

  1. Advanced structural analysis of nanoporous materials by thermal response measurements.

    Science.gov (United States)

    Oschatz, Martin; Leistner, Matthias; Nickel, Winfried; Kaskel, Stefan

    2015-04-07

    Thermal response measurements based on optical adsorption calorimetry are presented as a versatile tool for the time-saving and profound characterization of the pore structure of porous carbon-based materials. This technique measures the time-resolved temperature change of an adsorbent during adsorption of a test gas. Six carbide and carbon materials with well-defined nanopore architecture including micro- and/or mesopores are characterized by thermal response measurements based on n-butane and carbon dioxide as the test gases. With this tool, the pore systems of the model materials can be clearly distinguished and accurately analyzed. The obtained calorimetric data are correlated with the adsorption/desorption isotherms of the materials. The pore structures can be estimated from a single experiment due to different adsorption enthalpies/temperature increases in micro- and mesopores. Adsorption/desorption cycling of n-butane at 298 K/1 bar with increasing desorption time allows to determine the pore structure of the materials in more detail due to different equilibration times. Adsorption of the organic test gas at selected relative pressures reveals specific contributions of particular pore systems to the increase of the temperature of the samples and different adsorption mechanisms. The use of carbon dioxide as the test gas at 298 K/1 bar provides detailed insights into the ultramicropore structure of the materials because under these conditions the adsorption of this test gas is very sensitive to the presence of pores smaller than 0.7 nm.

  2. DEM modeling of flexible structures against granular material avalanches

    Science.gov (United States)

    Lambert, Stéphane; Albaba, Adel; Nicot, François; Chareyre, Bruno

    2016-04-01

    This article presents the numerical modeling of flexible structures intended to contain avalanches of granular and coarse material (e.g. rock slide, a debris slide). The numerical model is based on a discrete element method (YADE-Dem). The DEM modeling of both the flowing granular material and the flexible structure are detailed before presenting some results. The flowing material consists of a dry polydisperse granular material accounting for the non-sphericity of real materials. The flexible structure consists in a metallic net hanged on main cables, connected to the ground via anchors, on both sides of the channel, including dissipators. All these components were modeled as flexible beams or wires, with mechanical parameters defined from literature data. The simulation results are presented with the aim of investigating the variability of the structure response depending on different parameters related to the structure (inclination of the fence, with/without brakes, mesh size opening), but also to the channel (inclination). Results are then compared with existing recommendations in similar fields.

  3. Fluctuation electron microscopy studies of complex structured materials

    Science.gov (United States)

    Zhao, Gongpu; Rougée, Annick; Buseck, Peter; Treacy, Michael

    2008-03-01

    Fluctuation electron microscopy (FEM) is a hybrid imaging-diffraction technique. This technique is particularly sensitive to paracrystalline structures of dimension 0.5-2 nm, which are difficult to detect by either imaging or diffraction techniques alone. It has been successfully deployed to study paracrystalline structures in amorphous silicon, germanium thin film. This technique has also been used to study metallic glasses and oxide glasses. Until now, FEM has not been used to study disordered geological materials. In this talk we present our FEM studies of shungite, a naturally occurring disordered carbonaceous material, reveal that trace quantities of tightly curved graphene structures such as C60, or fragments of C60, is present in shungite. We also present results from our study of metamict zircon, whose crystal structure is destroyed by self-radiation during naturally occurring α decay events. Work is in progress to study the structural evolution during the metamictization process.

  4. Use of geonics scientific positions for designing of building composites for protective (fortification) structures

    Science.gov (United States)

    Fediuk, R. S.; Yevdokimova, Yu G.; Smoliakov, A. K.; Stoyushko, N. Yu; Lesovik, V. S.

    2017-07-01

    The examples of the implementation of the geological (geomimetic) positions in construction materials science are given in the work. The wall materials obtained with this technology have a much more developed surface than traditional wall materials. The second example of using such approaches is the development of internal care systems that will create a more highly organized structure of cement stone at the macro-, micro- and nano-scale levels and concrete in general at all stages: the stage of mixing, hardening and exploitation of the material. The regularities of the structure formation processes are revealed and the principles for increasing the efficiency of non-autoclaved aerated concrete due to application of composite binders, process control in a three-phase disperse porous system and the development of technological methods for the production of protective (fortification) structures are developed.

  5. Structure and dynamics in network-forming materials

    Science.gov (United States)

    Wilson, Mark

    2016-12-01

    The study of the structure and dynamics of network-forming materials is reviewed. Experimental techniques used to extract key structural information are briefly considered. Strategies for building simulation models, based on both targeting key (experimentally-accessible) materials and on systematically controlling key model parameters, are discussed. As an example of the first class of materials, a key target system, SiO2, is used to highlight how the changing structure with applied pressure can be effectively modelled (in three dimensions) and used to link to both experimental results and simple structural models. As an example of the second class the topology of networks of tetrahedra in the MX2 stoichiometry are controlled using a single model parameter linked to the M-X-M bond angles. The evolution of ordering on multiple length-scales is observed as are the links between the static structure and key dynamical properties. The isomorphous relationship between the structures of amorphous Si and SiO2 is discussed as are the similarities and differences in the phase diagrams, the latter linked to potential polyamorphic and ‘anomalous’ (e.g. density maxima) behaviour. Links to both two-dimensional structures for C, Si and Ge and near-two-dimensional bilayers of SiO2 are discussed. Emerging low-dimensional structures in low temperature molten carbonates are also uncovered.

  6. Deformation mechanisms in negative Poisson's ratio materials - Structural aspects

    Science.gov (United States)

    Lakes, R.

    1991-01-01

    Poisson's ratio in materials is governed by the following aspects of the microstructure: the presence of rotational degrees of freedom, non-affine deformation kinematics, or anisotropic structure. Several structural models are examined. The non-affine kinematics are seen to be essential for the production of negative Poisson's ratios for isotropic materials containing central force linkages of positive stiffness. Non-central forces combined with pre-load can also give rise to a negative Poisson's ratio in isotropic materials. A chiral microstructure with non-central force interaction or non-affine deformation can also exhibit a negative Poisson's ratio. Toughness and damage resistance in these materials may be affected by the Poisson's ratio itself, as well as by generalized continuum aspects associated with the microstructure.

  7. Compatibility of structural materials with liquid bismuth, lead, and mercury

    Energy Technology Data Exchange (ETDEWEB)

    Weeks, J.R. [Brookhaven National Lab., Upton, NY (United States)

    1996-06-01

    During the 1950s and 1960s, a substantial program existed at Brookhaven National Laboratory as part of the Liquid Metal Fuel reactor program on the compatibility of bismuth, lead, and their alloys with structural materials. Subsequently, compatibility investigations of mercury with structural materials were performed in support of development of Rankine cycle mercury turbines for nuclear applications. The present talk will review present understanding of the corrosion/mass-transfer reactions of structural materials with these liquid metal coolants. Topics to be discussed include the basic solubility relationships of iron, chromium, nickel, and refractory metals in these liquid metals, the results of inhibition studies, the role of oxygen on the corrosion processes, and specialized topics such as cavitation-corrosion and liquid metal embrittlement. Emphasis will be placed on utilizing the understanding gained in this earlier work on the development of heavy liquid metal targets in spallation neutron sources.

  8. Porous structures of natural materials and bionic design

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This investigation and morphology analysis of porous structure of some kinds of natural materials such as chicken eggshell, partridge eggshell, pig bone, and seeds of mung bean, soja, ginkgo, lotus seed, as well as the epidermis of apples, with SEM (Scanning Electronic Microscope) showed that natural structures' pores can be classified into uniform pores, gradient pores and multi pores from the viewpoint of the distribution variation of pore density, size and geometry. Furthermore, an optimal design of porous bearings was for the first time developed based on the gradient configuration of natural materials. The bionic design of porous structures is predicted to be widely developed and applied in the fields of materials and mechanical engineering in the future.

  9. Structural integrity of materials in nuclear service: a bibliography

    Energy Technology Data Exchange (ETDEWEB)

    Heddleson, F.A.

    1977-06-07

    This report contains 679 abstracts from the Nuclear Safety Information Center (NSIC) computer file dated 1973 through 1976 covering material properties with respect to structural integrity. All materials important to the nuclear industry (except concrete) are covered for mechanical properties, chemical properties, corrosion, fracture or failure, radiation damage, creep, cracking, and swelling. Keyword, author, and permuted-title indexes are included for the convenience of the user.

  10. Code qualification of structural materials for AFCI advanced recycling reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Li, M.; Majumdar, S.; Nanstad, R.K.; Sham, T.-L. (Nuclear Engineering Division); (ORNL)

    2012-05-31

    This report summarizes the further findings from the assessments of current status and future needs in code qualification and licensing of reference structural materials and new advanced alloys for advanced recycling reactors (ARRs) in support of Advanced Fuel Cycle Initiative (AFCI). The work is a combined effort between Argonne National Laboratory (ANL) and Oak Ridge National Laboratory (ORNL) with ANL as the technical lead, as part of Advanced Structural Materials Program for AFCI Reactor Campaign. The report is the second deliverable in FY08 (M505011401) under the work package 'Advanced Materials Code Qualification'. The overall objective of the Advanced Materials Code Qualification project is to evaluate key requirements for the ASME Code qualification and the Nuclear Regulatory Commission (NRC) approval of structural materials in support of the design and licensing of the ARR. Advanced materials are a critical element in the development of sodium reactor technologies. Enhanced materials performance not only improves safety margins and provides design flexibility, but also is essential for the economics of future advanced sodium reactors. Code qualification and licensing of advanced materials are prominent needs for developing and implementing advanced sodium reactor technologies. Nuclear structural component design in the U.S. must comply with the ASME Boiler and Pressure Vessel Code Section III (Rules for Construction of Nuclear Facility Components) and the NRC grants the operational license. As the ARR will operate at higher temperatures than the current light water reactors (LWRs), the design of elevated-temperature components must comply with ASME Subsection NH (Class 1 Components in Elevated Temperature Service). However, the NRC has not approved the use of Subsection NH for reactor components, and this puts additional burdens on materials qualification of the ARR. In the past licensing review for the Clinch River Breeder Reactor Project (CRBRP

  11. Multi-Material Design Optimization of Composite Structures

    DEFF Research Database (Denmark)

    Hvejsel, Christian Frier

    properties. The modeling encompasses discrete orientationing of orthotropic materials, selection between different distinct materials as well as removal of material representing holes in the structure within a unified parametrization. The direct generalization of two-phase topology optimization to any number...... of phases including void as a choice using the well-known material interpolation functions is novel. For practical multi-material design problems the parametrization leads to optimization problems with a large number of design variables limiting the applicability of combinatorial solution approaches...... or random search techniques. Thus, a main issue is the question of how to parametrize the originally discrete optimization problem in a manner making it suitable for solution using gradient-based algorithms. This is a central theme throughout the thesis and in particular two gradient-based approaches...

  12. Chemical compatibility of structural materials in alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Rink, D.L.; Haglund, R. [Argonne National Lab., Chicago, IL (United States)] [and others

    1995-04-01

    The objectives of this task are to (a) evaluate the chemical compatibility of structural alloys such as V-5 wt.%Cr-5 wt.%Ti alloy and Type 316 stainless steel for application in liquid alkali metals such as lithium and sodium-78 wt.% potassium (NaK) at temperatures in the range that are of interest for International Thermonuclear Experimental Reactor (ITER); (b) evaluate the transfer of nonmetallic elements such as oxygen, nitrogen, carbon, and hydrogen between structural materials and liquid metals; and (c) evaluate the effects of such transfers on the mechanical and microstructural characteristics of the materials for long-term service in liquid-metal-environments.

  13. Modeling high temperature materials behavior for structural analysis

    CERN Document Server

    Naumenko, Konstantin

    2016-01-01

    This monograph presents approaches to characterize inelastic behavior of materials and structures at high temperature. Starting from experimental observations, it discusses basic features of inelastic phenomena including creep, plasticity, relaxation, low cycle and thermal fatigue. The authors formulate constitutive equations to describe the inelastic response for the given states of stress and microstructure. They introduce evolution equations to capture hardening, recovery, softening, ageing and damage processes. Principles of continuum mechanics and thermodynamics are presented to provide a framework for the modeling materials behavior with the aim of structural analysis of high-temperature engineering components.

  14. Cell-based composite materials with programmed structures and functions

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-03-01

    The present invention is directed to the use of silicic acid to transform biological materials, including cellular architecture into inorganic materials to provide biocomposites (nanomaterials) with stabilized structure and function. In the present invention, there has been discovered a means to stabilize the structure and function of biological materials, including cells, biomolecules, peptides, proteins (especially including enzymes), lipids, lipid vesicles, polysaccharides, cytoskeletal filaments, tissue and organs with silicic acid such that these materials may be used as biocomposites. In many instances, these materials retain their original biological activity and may be used in harsh conditions which would otherwise destroy the integrity of the biological material. In certain instances, these biomaterials may be storage stable for long periods of time and reconstituted after storage to return the biological material back to its original form. In addition, by exposing an entire cell to form CSCs, the CSCs may function to provide a unique system to study enzymes or a cascade of enzymes which are otherwise unavailable.

  15. Laser-matter structuration of optical and biological materials

    Energy Technology Data Exchange (ETDEWEB)

    Hallo, L., E-mail: hallo@celia.u-bordeaux1.fr [CELIA, Universite Bordeaux 1 (France); Mezel, C., E-mail: candice.mezel@cea.fr [CELIA, Universite Bordeaux 1 (France); CEA Le Ripault, 37260 Monts (France); Guillemot, F., E-mail: fabien.guillemot@inserm.fr [UMR 577 INSERM, Universite Bordeaux 2 (France); Chimier, B., E-mail: chimier@celia.u-bordeaux1.fr [CELIA, Universite Bordeaux 1 (France); Bourgeade, A., E-mail: antoine.bourgeade@cea.fr [CEA-CESTA, Le Barp (France); Regan, C., E-mail: regan@celia.u-bordeaux1.fr [CELIA, Universite Bordeaux 1 (France); Duchateau, G., E-mail: duchateau@celia.u-bordeaux1.fr [CELIA, Universite Bordeaux 1 (France); Souquet, A., E-mail: agnes.souquet@inserm.fr [UMR 577 INSERM, Universite Bordeaux 2 (France); Hebert, D., E-mail: david.hebert@cea.fr [CEA-CESTA, Le Barp (France)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer In this study we model nanomaterial structuring. Black-Right-Pointing-Pointer The laser energy deposition is discussed first. Black-Right-Pointing-Pointer Full and approximate models are discussed. Black-Right-Pointing-Pointer Dynamic material response is addressed via hydrodynamics. Black-Right-Pointing-Pointer Sild effects are accounted for - Abstract: Interaction of ultrafast laser, i.e. from the femtosecond (fs) to the nanosecond (ns) regime, with initially transparent matter may produce very high energy density hot spots in the bulk as well as at the material surface, depending on focusing conditions. In the fs regime, absorption is due to ionisation of the dielectric, which enables absorption process to begin, and then hydrodynamic to take place. In the ns regime both absorption and hydrodynamic are coupled to each other, which complexifies considerably the comprehension but matter structuration looks similar. A numerical tool including solution of 3D Maxwell equations and a rate equation for free electrons is first compared to some available simple models of laser energy absorption. Then, subsequent material deformation, i.e. structuration, is determined by solving hydrodynamic equations, including or not solid behaviour. We show that nature of the final structures strongly depends on the amount of deposited energy and on the shape of the absorption zone. Then we address some problems related to laser-matter structuration of optical and biological materials in the fs, ps and ns regimes.

  16. The effects of coagulants on the structure of PBO materials

    Institute of Scientific and Technical Information of China (English)

    LI Jin-huan; HUANG Yu-dong; MENG Lin

    2006-01-01

    PBO materials possess super mechanical properties and high thermal and chemical resistance due to their special rigid-rod backbones with heterocyclic chemical structure and supermolecular microstructure. But these structures may be affected by a series of preparing technologies, among which the coagulant is even more important. In this paper the chemical and microstructure changes of PBO materials coagulated with different solvents were investigated. Analyses of molecular weight and chemical structure of PBO coagulated indicate that the heterocyclic ring of PBO will experience cleavage in coagulation and in this stage water plays an important role. The final structure of PBO materials may involve several intermediate structures lying between benzoxazole and the open ring. Wide-angle X-ray diffraction (WAXD) 2θ scans and scanning probe microscope (SPM) show that the microstructure of PBO materials coagulated in solvents with different properties will change a lot and those coagulants with the smaller rate of diffusion like methanol can cause more ordered molecule alignment containing fewer voids.

  17. Investigation of 6T SRAM memory circuit using high-k dielectrics based nano scale junctionless transistor

    Science.gov (United States)

    Charles Pravin, J.; Nirmal, D.; Prajoon, P.; Mohan Kumar, N.; Ajayan, J.

    2017-04-01

    In this paper the Dual Metal Surround Gate Junctionless Transistor (DMSGJLT) has been implemented with various high-k dielectric. The leakage current in the device is analysed in detail by obtaining the band structure for different high-k dielectric material. It is noticed that with increasing dielectric constant the device provides more resistance for the direct tunnelling of electron in off state. The gate oxide capacitance also shows 0.1 μF improvement with Hafnium Oxide (HfO2) than Silicon Oxide (SiO2). This paved the way for a better memory application when high-k dielectric is used. The Six Transistor (6T) Static Random Access Memory (SRAM) circuit implemented shows 41.4% improvement in read noise margin for HfO2 than SiO2. It also shows 37.49% improvement in write noise margin and 30.16% improvement in hold noise margin for HfO2 than SiO2.

  18. Phosphorus recovery by mesoporous structure material from wastewater.

    Science.gov (United States)

    Lee, S H; Lee, B C; Lee, K W; Lee, S H; Choi, Y S; Park, K Y; Iwamoto, M

    2007-01-01

    This study was designed to investigate the fundamental aspects of a possible removal of phosphorous from wastewater by using the mesoporous structure materials for wastewater reuse. The zirconium sulphate with mesoporous structure as a new type of ion exchangers was synthesised by hydrothermal reaction. From the results of X-ray diffraction and transmission electron microscope, it was discovered that the synthesised material had hexagonal mesoporous structure with a pore size of approximately 40-50A. Experimental results showed that the zirconium sulphate with mesoporous structure had very high sorption capacity for the phosphorus. The novel ion exchange occurred between PO4(3-) and SO4(2-), OH-. The amount of phosphate ions exchanged into the solid was as great as 3.4 mmol/g-ZS. Furthermore, it is possible to obtain a higher removal efficiency than other ion exchange media and adsorbents.

  19. CALCULATION OF TRANSFORMATION DRIVING FORCE FOR THE PRECIPITATION OF NANO-SCALED CEMENTITES IN THE HYPOEUTECTOID STEELS THROUGH ULTRA FAST COOLING%超快速冷却条件下亚共析钢中纳米级渗碳体析出的相变驱动力计算

    Institute of Scientific and Technical Information of China (English)

    王斌; 刘振宇; 周晓光; 王国栋

    2013-01-01

    rolling on the precipitation behavior of nano-scale cementite particles was investigated. Based on the calculation results, the driving force of degenerated pearlitic transformation is the most negative in the three transformation mechanisms, at the same undercooled temperature, which theoretically indicates that the degenerated pearlitic transformation of undercooled austenite can easily occur to form cementite and ferrite with the equilibrium concentrations. In practical manufacturing, the diffusion of carbon atoms could be restrained by decreasing temperature in short time in the application of UFC, as a result that cementites would most likely dispersed in the form of nano-scaled particles directly, rather than being fully grown up into lamellar pealites. Due to the UFC, a large number of dispersed nano-scaled cementite areas were found in the microstructure of hot-rolled hypoeutectoid experiment steels, where the size of the cementites was within the range often to tens nanometers. The precipitation of nano-scaled cementites was realized without the micro-alloying elements. Moreover, there were a lot of carbon-rich areas in the microstructure of undercooled austenite, based on the equilibrium concentration calculation, in which the local mole fraction of carbon could be from 0.04 to 0.08, and this part of austenite with the high carbon concentration was apt to decompose and form likely the precipitation of nano-scaled cementites.

  20. New smart materials to address issues of structural health monitoring.

    Energy Technology Data Exchange (ETDEWEB)

    Chaplya, Pavel Mikhail

    2004-12-01

    Nuclear weapons and their storage facilities may benefit from in-situ structural health monitoring systems. Appending health-monitoring functionality to conventional materials and structures has been only marginally successful. The purpose of this project was to evaluate feasibility of a new smart material that includes self-sensing health monitoring functions similar to that of a nervous system of a living organism. Reviews of current efforts in the fields of heath-monitoring, nanotechnology, micro-electromechanical systems (MEMS), and wireless sensor networks were conducted. Limitations of the current nanotechnology methods were identified and new approaches were proposed to accelerate the development of self-sensing materials. Wireless networks of MEMS sensors have been researched as possible prototypes of self-sensing materials. Sensor networks were also examined as enabling technologies for dense data collection techniques to be used for validation of numerical methods and material parameter identification. Each grain of the envisioned material contains sensors that are connected in a dendritic manner similar to networks of neurons in a nervous system. Each sensor/neuron can communicate with the neighboring grains. Both the state of the sensor (on/off) and the quality of communication signal (speed/amplitude) should indicate not only a presence of a structural defect but the nature of the defect as well. For example, a failed sensor may represent a through-grain crack, while a lost or degraded communication link may represent an inter-granular crack. A technology to create such material does not exist. While recent progress in the fields of MEMS and nanotechnology allows to envision these new smart materials, it is unrealistic to expect creation of self-sensing materials in the near future. The current state of MEMS, nanotechnology, communication, sensor networks, and data processing technologies indicates that it will take more than ten years for the

  1. Low-density, polymer foams as structural models for phase-separation in polymer solutions

    Energy Technology Data Exchange (ETDEWEB)

    Beaucage, G. [Univ. of Cincinnati, OH (United States); Lagasse, R.R.; Aubert, J.H. [Sandia National Labs., Albuquerque, NM (United States)] [and others

    1995-12-31

    Low density polymer foams are produced through nano-scale phase separation of 5 to 15% solutions yielding gels. The gels are solvent exchanged and dried by supercritical extraction. We have found that the morphology of the phase separated gel, the intermediate solvent exchanged gels and the final foams are essentially identical over a wide range of size. Through the combination of several scattering techniques covering many decades of size we can distinguish structural levels in these low-density foams. The combined scattering data spans sizes ranging from 10{mu}m to 1{Angstrom}. A recently developed global fitting approach can describe the multiple levels of structure observed in these complex materials. Several morphological classes of foams are observed. A perplexing feature in the scattering patterns from all of the foams is a 3-dimensional structure with a radius of gyration from 40 to 100{Angstrom}. By variation of the polymer molecular-weight, scattering data supports a model describing this nano-scale structure as partially isolated, collapsed polymer coils. This model indicates that collapsed base structural unit in these morphologies.

  2. Modelling of advanced structural materials for GEN IV reactors

    Science.gov (United States)

    Samaras, M.; Hoffelner, W.; Victoria, M.

    2007-09-01

    The choice of suitable materials and the assessment of long-term materials damage are key issues that need to be addressed for the safe and reliable performance of nuclear power plants. Operating conditions such as high temperatures, irradiation and a corrosive environment degrade materials properties, posing the risk of very expensive or even catastrophic plant damage. Materials scientists are faced with the scientific challenge to determine the long-term damage evolution of materials under service exposure in advanced plants. A higher confidence in life-time assessments of these materials requires an understanding of the related physical phenomena on a range of scales from the microscopic level of single defect damage effects all the way up to macroscopic effects. To overcome lengthy and expensive trial-and-error experiments, the multiscale modelling of materials behaviour is a promising tool, bringing new insights into the fundamental understanding of basic mechanisms. This paper presents the multiscale modelling methodology which is taking root internationally to address the issues of advanced structural materials for Gen IV reactors.

  3. Materializing a responsive interior: designing minimum energy structures

    DEFF Research Database (Denmark)

    Mossé, Aurélie; Kofod, Guggi; Ramsgaard Thomsen, Mette

    2011-01-01

    -active structures based on dielectric-elastomer, where energy-minimization and self-organization principles become central processes for the realization of shape-changing architectural surfaces. In Reef, a concept for self-actuated ceiling surface, we examine the integration of these dynamic structures...... (Lendlein, Kelch 2002) or light (van Oosten, Bastiaansen et al. 2009). All in all, this approach could form a whole new design paradigm, in which efficient 2D-manufacturing can lead to highly flexible, low weight and adaptable 3D-structures. This is illustrated by the design and manufacture of electro......This paper discusses a series of design-led experiments investigating future possibilities for architectural materialization relying on minimum energy structures as an example of adaptive structure. The structures have been made as laminates of elastic membrane under high tension with flexible...

  4. Feeding of nano scale oats β-glucan enhances the host resistance against Edwardsiella tarda and protective immune modulation in zebrafish larvae.

    Science.gov (United States)

    Udayangani, R M C; Dananjaya, S H S; Fronte, Baldassare; Kim, Cheol-Hee; Lee, Jehee; De Zoysa, Mahanama

    2017-01-01

    In this study, we prepared and characterized the oats origin of nano scale β-glucan (NBG) and investigated the immunomodulatory properties in zebrafish larvae. Newly prepared NBG (average particle size of 465 nm) was fully soluble in water. Zebrafish larvae survival rate was increased against pathogenic bacteria Edwardsiella tarda, when NBG was added to the water (500 μg/mL) compared to NBG non-exposed controls. Moreover, quantitative real time PCR (qRT-PCR) results showed up-regulation of immune functional genes including TNF-α, IL-1β, β-defensin, lysozyme, IL 10, IL 12 and C-Rel indicating higher survival rate could be due to stronger immunomodulatory function of NBG (500 μg/mL). Thus, non-toxic, water soluble and biodegradable NBG from oats could be considered as the potential immunostimulant for larval aquaculture. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. An investigation of the effects of history dependent damage in time dependent fracture mechanics: nano-scale studies of damage evolution

    Energy Technology Data Exchange (ETDEWEB)

    Brust, F.W. (Bud) Jr; Mohan, R.; Yang, Y.P.; Oh, J.; Katsube, N.

    2002-12-01

    High-temperature operation of technical engineering systems is critical for system efficiency, and will be a key driver in the future US DOE energy policy. Developing an understanding of high-temperature creep and creep-fatigue failure processes is a key driver for the research work described here. The focus is on understanding the high-temperature deformation and damage development on the nano-scale (50 to 500 nm) level. The high-temperature damage development process, especially with regard to low and high cyclic loading, which has received little attention to date, is studied. Damage development under cyclic loading develops in a fashion quite different from the constant load situation. The development of analytical methodologies so that high-temperature management of new systems can be realized is the key goal of this work.

  6. An in-situ nano-scale swelling-filling strategy to improve overall performance of Nafion membrane for direct methanol fuel cell application

    Science.gov (United States)

    Li, Jing; Fan, Kun; Cai, Weiwei; Ma, Liying; Xu, Guoxiao; Xu, Sen; Ma, Liang; Cheng, Hansong

    2016-11-01

    A novel in-situ nano-scale swelling-filling (SF) strategy is proposed to modify commercial Nafion membranes for performance enhancement of direct methanol fuel cells (DMFCs). A Nafion membrane was filled in-situ with proton conductive macromolecules (PCMs) in the swelling process of a Nafion membrane in a PCM solution. As a result, both proton conductivity and methanol-permeation resistivity of the SF-treated Naifion membrane was substantially improved with the selectivity nearly doubled compared to the original Nafion membrane. The mechanical strength of the optimal SF treated Nafion membrane was also enforced due to the strong interaction between the PCM fillers and the Nafion molecular chains. As a result, a DMFC equipped with the SF-treated membrane yielded a 33% higher maximum power density than that offered by the DMFC with the original Nafion membrane.

  7. Radiation damage of biomolecular systems: Nano-scale insights into Ion-beam cancer therapy. 2nd Nano-IBCT conference

    Science.gov (United States)

    Śmiałek, Małgorzata A.; Limão-Vieira, Paulo; Mason, Nigel J.; Solov'yov, Andrey V.

    2014-10-01

    The second Nano-IBCT conference of the COST Action MP1002: Nanoscale Insights into Ion Beam Cancer Therapy was held in Sopot, Poland, from May 20th to May 24th, 2013. The Nano-IBCT action had been launched in December 2010 and brings together experts from different disciplines (physics, chemistry, biology, hadron-therapy centres, medical institutions), with specialisms in the radiation damage of biological matter. This meeting follows up the first one that was held in October, 2011 in Caen, France and we were pleased to see again so many of the participants of the previous meeting as well as to welcome some new colleagues joining and sharing their knowledge and expertise in this field. Contribution to the Topical Issue "Nano-scale Insights into Ion-beam Cancer Therapy", edited by Andrey V. Solov'yov, Nigel Mason, Paulo Limão-Vieira and Malgorzata Smialek-Telega.

  8. Nanoscale dose deposition in cell structures under X-ray irradiation treatment assisted with nanoparticles of a set of elements: an analytical approach to cell survival

    Energy Technology Data Exchange (ETDEWEB)

    Melo B, W.; Barboza F, M. [Universidad de Sonora, Departamento de Investigacion en Fisica, 83000 Hermosillo, Sonora (Mexico); Chernov, G., E-mail: g.chernovch@gmail.com [Universidad de Sonora, Departamento de Fisica, 83000 Hermosillo, Sonora (Mexico)

    2016-10-15

    The goal of combining nanoparticles (Nps) with radiation therapy is to increase the differential effect between healthy and tumor tissues. Only some elements have been investigated to be used as radiosensitizers and no systematic experimental or theoretical comparisons between different materials have been developed. MacMahon, et al. (Nano scale, 2016, 8, 581) presents the first systematic computational study of the impact of elemental composition on nanoparticle radiation interaction for kilo voltage and megavoltage X-ray exposure, for a range of elements (Z = 14 - 80). In this study we present and analytical model to assess the cell survival modification responses of cell cultures under irradiation treatments with keV X-rays assisted with Nps of different materials as platinum, hafnium, gadolinium, gold, germanium, iodine and iron. This model starts from the data of radial dose deposition around a single 20 nm diameter Np irradiated with photons of an energy 20 keV higher than the element K-shell binding energy to the nano scale probability of dose distribution inside cell structures with embedded Nps (the assessment of the average dose and the average squared dose in cell structure). Also based on the Local Effect Model we estimate potential biological effects, as is the case of the Relative Biological Effectiveness (RBE). Nano scale dose deposition exhibits a complex dependence on atomic number, as a consequence of the variations in secondary Auger electron spectra, this is manifested in significant variations in RBE. Upon in vitro experiments RBE varies from 1 to 1.6. Values representative of a high radiosensitization were observed for lower energies, ones that are well reproduced by our analytical analysis for cell cultures with a homogeneous distribution of different material Nps. (Author)

  9. Effects on electrochemical performances for host material caused by structure change of modifying material.

    Science.gov (United States)

    Zhang, Yantao; Zhou, Enlou; Song, Dawei; Shi, Xixi; Wang, Xiaoqing; Guo, Jian; Zhang, Lianqi

    2014-09-01

    High ionic conductive lithium niobium oxides were selected as the modifying material to investigate the effects on the electrochemical performances for host material LiNi1/3Co1/3Mn1/3O2 caused by the structure change of the modifying material at various calcination temperatures and modifying amounts. X-ray diffraction (XRD) studies revealed that the structure of the modifying material was single LiNbO3 phase after being calcined at 500 °C and changed to LiNbO3-Li3NbO4 mixture phases at 600 and 700 °C, and further changed to single Li3NbO4 phase at 800 °C. Electrochemical tests displayed that both LiNbO3 and Li3NbO4 phases of modifying material could contribute to the improvement of the cycle performances for the host material, but the improvement degree of Li3NbO4 phase was more evident. The cycle performances and high rate performances of the modified host material (calcined at 700 °C) electrodes were improved with the right modifying amount.

  10. Continuum theory of defects - Structural-analytical mechanics of materials

    Science.gov (United States)

    Likhachev, V. A.; Volkov, A. E.; Shudegov, V. E.

    The fundamental concepts of the continuum theory of defects in crystals are examined including dislocations, disclinations, and planar defects. The principal plastic characteristics of materials are then calculated using these concepts. Elements of deformation theory for piecewise inhomogeneous bodies with a structural hierarchy and phase transformations are examined. The nature of the amorphous state is discussed.

  11. Highlighting material structure with transmission electron diffraction correlation coefficient maps.

    Science.gov (United States)

    Kiss, Ákos K; Rauch, Edgar F; Lábár, János L

    2016-04-01

    Correlation coefficient maps are constructed by computing the differences between neighboring diffraction patterns collected in a transmission electron microscope in scanning mode. The maps are shown to highlight material structural features like grain boundaries, second phase particles or dislocations. The inclination of the inner crystal interfaces are directly deduced from the resulting contrast.

  12. The structure of the "amorphous" matrix of keratins.

    Science.gov (United States)

    Kadir, Murat; Wang, Xinwei; Zhu, Bowen; Liu, Jing; Harland, Duane; Popescu, Crisan

    2017-05-01

    Various keratin fibers, particularly human hairs, were investigated by transmission electron microscopy, TEM, solid-state (1)H NMR and Transient Electro-Thermal Technique, TET. The results converge to suggest that the matrix of keratin fiber cortex, far from being amorphous, has a well-defined nano-scale grainy structure, the size of these grains being around 2-4nm. The size of the grains appears to strongly depend on the chemical treatment of the fiber, on the temperature and on the relative humidity of the environment, as well as on the physiological factors at the level of fiber production in follicle. By suggesting an organization at the nano-scale of the protein chains in these grains, likely to be Keratin Associated Proteins, the results challenge the view of matrix as a homogeneous glassy material. Moreover, they indicate the potential of further investigating the purpose of this structure that appears to reflect not only chemical treatments of keratins but also biological processes at the level of the follicle. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. RILEM International Symposium on Materials and Joints in Timber Structures

    CERN Document Server

    Reinhardt, H-W; Garrecht, Harald

    2014-01-01

    This book contains the contributions from the RILEM International Symposium on Materials and Joints in Timber Structures that was held in Stuttgart, Germany from October 8 to 10, 2013. It covers recent developments in the materials and the joints used in modern timber structures. Regarding basic wooden materials, the contributions highlight the widened spectrum of products comprising cross-laminated timber, glulam and LVL from hardwoods and block glued elements. Timber concrete compounds, cement bonded wood composites and innovative light-weight constructions represent increasingly employed alternatives for floors, bridges and facades. With regard to jointing technologies, considerable advances in both mechanical connections and glued joints are presented. Self-tapping screws have created unprecedented options for reliable, strong as well as ductile joints and reinforcement technologies. Regarding adhesives, which constitute the basis of the jointing/laminating technology of modern timber products, extended o...

  14. Identification of material properties of sandwich structure with piezoelectric patches

    Directory of Open Access Journals (Sweden)

    Zemčík R.

    2008-11-01

    Full Text Available The work focuses on light-weight sandwich structures made of carbon-epoxy skins and foam core which have unique bending stiffness compared to conventional materials. The skins are manufactured by vacuum autoclave technology from unidirectional prepregs and the sandwich is then glued together. The resulting material properties of the structure usually differ from those provided by manufacturer or even those obtained from experimental tests on separate materials, which makes computational models unreliable. Therefore, the properties are identified using the combination of experimental analysis of the sandwich with attached piezoelectric transducer and corresponding static and modal finite element analyses. Simple mathematical optimization with repetitive finite element solution is used. The model is then verified by transient analysis when the piezoelectric patch is excited by harmonic signals covering the first two eigen-frequencies and the induced oscillations are measured by laser sensor.

  15. Material Properties Analysis of Structural Members in Pumpkin Balloons

    Science.gov (United States)

    Sterling, W. J.

    2003-01-01

    The efficient design, service-life qualification, and reliability predictions for lightweight aerospace structures require careful mechanical properties analysis of candidate structural materials. The demand for high-quality laboratory data is particularly acute when the candidate material or the structural design has little history. The pumpkin-shaped super-pressure balloon presents both challenges. Its design utilizes load members (tendons) extending from apex to base around the gas envelope to achieve a lightweight structure. The candidate tendon material is highly weight-efficient braided HM cord. Previous mechanical properties studies of Zylon have focused on fiber and yarn, and industrial use of the material in tensile applications is limited. For high-performance polymers, a carefully plamed and executed properties analysis scheme is required to ensure the data are relevant to the desired application. Because no directly-applicable testing standard was available, a protocol was developed based on guidelines fiom professional and industry organizations. Due to the liquid-crystalline nature of the polymer, the cord is very stiff, creeps very little, and does not yield. Therefore, the key material property for this application is the breaking strength. The pretension load and gauge length were found to have negligible effect on the measured breaking strength over the ranges investigated. Strain rate was found to have no effect on breaking strength, within the range of rates suggested by the standards organizations. However, at the lower rate more similar to ULDB operations, the strength was reduced. The breaking strength increased when the experiment temperature was decreased from ambient to 183K which is the lowest temperature ULDB is expected to experience. The measured strength under all test conditions was well below that resulting from direct scale-up of fiber strength based on the manufacturers data. This expected result is due to the effects of the

  16. Evaluation of structural safety of existing structures, based on actual material properties and geometry

    NARCIS (Netherlands)

    Bijlaard, F.S.K.

    1999-01-01

    This paper presents an overview of the structural assessment of existing structures in comparison to that of newly designed structures. The role of measuring geometrical data and testing the material properties is explained. The method provides objective criteria to judge the safety of existing stru

  17. Structural integrity of engineering composite materials: a cracking good yarn.

    Science.gov (United States)

    Beaumont, Peter W R; Soutis, Costas

    2016-07-13

    Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Where human life depends upon engineering ingenuity, the burden of testing to prove a 'fracture safe design' is immense. Fitness considerations for long-life implementation of large composite structures include understanding phenomena such as impact, fatigue, creep and stress corrosion cracking that affect reliability, life expectancy and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined, and takes service duty into account. However, there are conflicting aims in the complete design process of designing simultaneously for high efficiency and safety assurance throughout an economically viable lifetime with an acceptable level of risk. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

  18. On the Mechanical Behavior of Advanced Composite Material Structures

    Science.gov (United States)

    Vinson, Jack

    During the period between 1993 and 2004, the author, as well as some colleagues and graduate students, had the honor to be supported by the Office of Naval Research to conduct research in several aspects of the behavior of structures composed of composite materials. The topics involved in this research program were numerous, but all contributed to increasing the understanding of how various structures that are useful for marine applications behaved. More specifically, the research topics focused on the reaction of structures that were made of fiber reinforced polymer matrix composites when subjected to various loads and environmental conditions. This included the behavior of beam, plate/panel and shell structures. It involved studies that are applicable to fiberglass, graphite/carbon and Kevlar fibers imbedded in epoxy, polyester and other polymeric matrices. Unidirectional, cross-ply, angle ply, and woven composites were involved, both in laminated, monocoque as well as in sandwich constructions. Mid-plane symmetric as well as asymmetric laminates were studied, the latter involving bending-stretching coupling and other couplings that only can be achieved with advanced composite materials. The composite structures studied involved static loads, dynamic loading, shock loading as well as thermal and hygrothermal environments. One major consideration was determining the mechanical properties of composite materials subjected to high strain rates because the mechanical properties vary so significantly as the strain rate increases. A considerable number of references are cited for further reading and study for those interested.

  19. Light thermal structures and materials for high speed flight

    Science.gov (United States)

    Thornton, Earl A.

    1992-01-01

    Over the last twenty years, unified viscoplastic constitutive models have evolved to meet this need. These constitutive models provide a means for representing a material's response from the elastic through the plastic range including strain-rate dependent plastic flow, creep, and stress relaxation. Rate-dependent plasticity effects are known to be important at elevated temperatures. The purpose of this paper is to describe computational and experimental research programs underway at the Light Thermal Structures Center focused on the investigation of the response of structures and materials to local heating. In the first part of the paper, finite element thermoviscoplastic analysis is highlighted. In the second part of the paper, the thermal-structures experimental program is outlined.

  20. Basic materials and structures aspects for hypersonic transport vehicles (HTV)

    Science.gov (United States)

    Steinheil, E.; Uhse, W.

    A Mach 5 transport design is used to illustrate structural concepts and criteria for materials selections and also key technologies that must be followed in the areas of computational methods, materials and construction methods. Aside from the primary criteria of low weight, low costs, and conceivable risks, a number of additional requirements must be met, including stiffness and strength, corrosion resistance, durability, and a construction adequate for inspection, maintenance and repair. Current aircraft construction requirements are significantly extended for hypersonic vehicles. Additional consideration is given to long-duration temperature resistance of the airframe structure, the integration of large-volume cryogenic fuel tanks, computational tools, structural design, polymer matrix composites, and advanced manufacturing technologies.

  1. Pelamis WEC - main body structural design and materials selection

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, C.

    2003-07-01

    This report summarises the results of a study evaluating the potential use of rolled steel, glass reinforced plastic, wood-epoxy laminate, and different forms of concrete as primary structural materials for the Pelamis Wave Energy Converter (WEC) as part of a strategy to refine the design by highlighting cost savings for long-term manufacture. Details are given of the drawing up of a load spectrum in order to assess the candidate structures, the choice of glass reinforced plastic, concrete, and steel for further evaluation based on preliminary screening, the assessment of the material requirements for each candidate structure, and cost estimates. The advantages of the use of concrete are discussed and recommendations are presented.

  2. Global Materials Structure Search with Chemically Motivated Coordinates.

    Science.gov (United States)

    Panosetti, Chiara; Krautgasser, Konstantin; Palagin, Dennis; Reuter, Karsten; Maurer, Reinhard J

    2015-12-01

    Identification of relevant reaction pathways in ever more complex composite materials and nanostructures poses a central challenge to computational materials discovery. Efficient global structure search, tailored to identify chemically relevant intermediates, could provide the necessary first-principles atomistic insight to enable a rational process design. In this work we modify a common feature of global geometry optimization schemes by employing automatically generated collective curvilinear coordinates. The similarity of these coordinates to molecular vibrations enhances the generation of chemically meaningful trial structures for covalently bound systems. In the application to hydrogenated Si clusters, we concomitantly observe a significantly increased efficiency in identifying low-energy structures and exploit it for an extensive sampling of potential products of silicon-cluster soft landing on Si(001) surfaces.

  3. Interpenetration in coordination polymers: structural diversities toward porous functional materials

    Directory of Open Access Journals (Sweden)

    Ritesh Haldar

    2015-03-01

    Full Text Available Interpenetration is a natural phenomenon frequently encountered in porous coordination polymers (PCPs or metal-organic frameworks (MOFs. Traditionally interpenetration has been considered as a threat to permanent porosity and several strategies have been adopted to control the framework interpenetration. Recent literature reports have unveiled that interpenetration has paramount importance in several material properties particularly in storage and separation of small gas molecules. Such frameworks also show interesting structural flexibility based on shearing or movement of the nets and also reveals guest induced dynamic structural transformation for modulated specific functions. In this review, we will emphasize several interpenetration phenomena observed in coordination polymers, their intriguing structural aspects and fascinating material properties.

  4. Functional materials discovery using energy-structure-function maps

    Science.gov (United States)

    Pulido, Angeles; Chen, Linjiang; Kaczorowski, Tomasz; Holden, Daniel; Little, Marc A.; Chong, Samantha Y.; Slater, Benjamin J.; McMahon, David P.; Bonillo, Baltasar; Stackhouse, Chloe J.; Stephenson, Andrew; Kane, Christopher M.; Clowes, Rob; Hasell, Tom; Cooper, Andrew I.; Day, Graeme M.

    2017-03-01

    Molecular crystals cannot be designed in the same manner as macroscopic objects, because they do not assemble according to simple, intuitive rules. Their structures result from the balance of many weak interactions, rather than from the strong and predictable bonding patterns found in metal-organic frameworks and covalent organic frameworks. Hence, design strategies that assume a topology or other structural blueprint will often fail. Here we combine computational crystal structure prediction and property prediction to build energy-structure-function maps that describe the possible structures and properties that are available to a candidate molecule. Using these maps, we identify a highly porous solid, which has the lowest density reported for a molecular crystal so far. Both the structure of the crystal and its physical properties, such as methane storage capacity and guest-molecule selectivity, are predicted using the molecular structure as the only input. More generally, energy-structure-function maps could be used to guide the experimental discovery of materials with any target function that can be calculated from predicted crystal structures, such as electronic structure or mechanical properties.

  5. Failure modes and materials design for biomechanical layer structures

    Science.gov (United States)

    Deng, Yan

    Ceramic materials are finding increasing usage in the area of biomechanical replacements---dental crowns, hip and bone implants, etc.---where strength, wear resistance, biocompatibility, chemical durability and even aesthetics are critical issues. Aesthetic ceramic crowns have been widely used in dentistry to replace damaged or missing teeth. However, the failure rates of ceramic crowns, especially all-ceramic crowns, can be 1%˜6% per year, which is not satisfactory to patients. The materials limitations and underlying fracture mechanisms of these prostheses are not well understood. In this thesis, fundamental fracture and damage mechanisms in model dental bilayer and trilayer structures are studied. Principle failure modes are identified from in situ experimentation and confirmed by fracture mechanics analysis. In bilayer structures of ceramic/polycarbonate (representative of ceramic crown/dentin structure), three major damage sources are identified: (i) top-surface cone cracks or (ii) quasiplasticity, dominating in thick ceramic bilayers; (iii) bottom-surface radial cracks, dominating in thin ceramic bilayers. Critical load P for each damage mode are measured in six dental ceramics: Y-TZP zirconia, glass-infiltrated zirconia and alumina (InCeram), glass-ceramic (Empress II), Porcelain (Mark II and Empress) bonded to polymer substrates, as a function of ceramic thickness d in the range of 100 mum to 10 mm. P is found independent of d for mode (i) and (ii), but has a d 2 relations for mode (iii)---bottom surface radial cracking. In trilayer structures of glass/core-ceramic/polycarbonate (representing veneer porcelain/core/dentin structures), three inner fracture origins are identified: radial cracks from the bottom surface in the (i) first and (ii) second layers; and (iii) quasiplasticity in core-ceramic layer. The role of relative veneer/core thickness, d1/d 2 and materials properties is investigated for three core materials with different modulus (114--270GPa

  6. Biologically inspired autonomous structural materials with controlled toughening and healing

    Science.gov (United States)

    Garcia, Michael E.; Sodano, Henry A.

    2010-04-01

    The field of structural health monitoring (SHM) has made significant contributions in the field of prognosis and damage detection in the past decade. The advantageous use of this technology has not been integrated into operational structures to prevent damage from propagating or to heal injured regions under real time loading conditions. Rather, current systems relay this information to a central processor or human operator, who then determines a course of action such as altering the mission or scheduling repair maintenance. Biological systems exhibit advanced sensory and healing traits that can be applied to the design of material systems. For instance, bone is the major structural component in vertebrates; however, unlike modern structural materials, bone has many properties that make it effective for arresting the propagation of cracks and subsequent healing of the fractured area. The foremost goal for the development of future adaptive structures is to mimic biological systems, similar to bone, such that the material system can detect damage and deploy defensive traits to impede damage from propagating, thus preventing catastrophic failure while in operation. After sensing and stalling the propagation of damage, the structure must then be repaired autonomously using self healing mechanisms motivated by biological systems. Here a novel autonomous system is developed using shape memory polymers (SMPs), that employs an optical fiber network as both a damage detection sensor and a network to deliver stimulus to the damage site initiating adaptation and healing. In the presence of damage the fiber optic fractures allowing a high power laser diode to deposit a controlled level of thermal energy at the fractured sight locally reducing the modulus and blunting the crack tip, which significantly slows the crack growth rate. By applying a pre-induced strain field and utilizing the shape memory recovery effect, thermal energy can be deployed to close the crack and return

  7. Advanced composite structural concepts and materials technologies for primary aircraft structures: Advanced material concepts

    Science.gov (United States)

    Lau, Kreisler S. Y.; Landis, Abraham L.; Chow, Andrea W.; Hamlin, Richard D.

    1993-01-01

    To achieve acceptable performance and long-term durability at elevated temperatures (350 to 600 F) for high-speed transport systems, further improvements of the high-performance matrix materials will be necessary to achieve very long-term (60,000-120,000 service hours) retention of mechanical properties and damage tolerance. This report emphasizes isoimide modification as a complementary technique to semi-interpenetrating polymer networks (SIPN's) to achieve greater processibility, better curing dynamics, and possibly enhanced thermo-mechanical properties in composites. A key result is the demonstration of enhanced processibility of isoimide-modified linear and thermo-setting polyimide systems.

  8. Local structure probes of nanoscale heterogeneity in crystalline materials.

    Science.gov (United States)

    Conradson, S; Espinosa, F; Villella, P

    2001-03-01

    In the conventional model of condensed matter increasing numbers of defects break down the order and ultimately convert perfect periodic crystals into aperiodic glasses. Local structure probes of a variety of materials with non-stoichiometric compositions, multiple degenerate ordering modes, or other symmetry breaking factors identify multiple ordered arrangements of atoms that render the materials heterogeneous on the nanometer scale. While exerting apparently negligible effects on bulk properties, this heterogeneity or phase separation does influence correlated or collective properties such as magnetism and phase stability.

  9. Fast Detection of Material Deformation through Structural Dissimilarity

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela; Perciano, Talita; Parkinson, Dilworth

    2015-10-29

    Designing materials that are resistant to extreme temperatures and brittleness relies on assessing structural dynamics of samples. Algorithms are critically important to characterize material deformation under stress conditions. Here, we report on our design of coarse-grain parallel algorithms for image quality assessment based on structural information and on crack detection of gigabyte-scale experimental datasets. We show how key steps can be decomposed into distinct processing flows, one based on structural similarity (SSIM) quality measure, and another on spectral content. These algorithms act upon image blocks that fit into memory, and can execute independently. We discuss the scientific relevance of the problem, key developments, and decomposition of complementary tasks into separate executions. We show how to apply SSIM to detect material degradation, and illustrate how this metric can be allied to spectral analysis for structure probing, while using tiled multi-resolution pyramids stored in HDF5 chunked multi-dimensional arrays. Results show that the proposed experimental data representation supports an average compression rate of 10X, and data compression scales linearly with the data size. We also illustrate how to correlate SSIM to crack formation, and how to use our numerical schemes to enable fast detection of deformation from 3D datasets evolving in time.

  10. Focusing of Acoustic Waves through Acoustic Materials with Subwavelength Structures

    KAUST Repository

    Xiao, Bingmu

    2013-05-01

    In this thesis, wave propagation through acoustic materials with subwavelength slits structures is studied. Guided by the findings, acoustic wave focusing is achieved with a specific material design. By using a parameter retrieving method, an effective medium theory for a slab with periodic subwavelength cut-through slits is successfully derived. The theory is based on eigenfunction solutions to the acoustic wave equation. Numerical simulations are implemented by the finite-difference time-domain (FDTD) method for the two-dimensional acoustic wave equation. The theory provides the effective impedance and refractive index functions for the equivalent medium, which can reproduce the transmission and reflection spectral responses of the original structure. I analytically and numerically investigate both the validity and limitations of the theory, and the influences of material and geometry on the effective spectral responses are studied. Results show that large contrasts in impedance and density are conditions that validate the effective medium theory, and this approximation displays a better accuracy for a thick slab with narrow slits in it. Based on the effective medium theory developed, a design of a at slab with a snake shaped" subwavelength structure is proposed as a means of achieving acoustic focusing. The property of focusing is demonstrated by FDTD simulations. Good agreement is observed between the proposed structure and the equivalent lens pre- dicted by the theory, which leads to robust broadband focusing by a thin at slab.

  11. Uncertainty Quantification in Experimental Structural Dynamics Identification of Composite Material Structures

    DEFF Research Database (Denmark)

    Luczak, Marcin; Peeters, Bart; Kahsin, Maciej

    2014-01-01

    Aerospace and wind energy structures are extensively using components made of composite materials. Since these structures are subjected to dynamic environments with time-varying loading conditions, it is important to model their dynamic behavior and validate these models by means of vibration...... for uncertainty evaluation in experimentally estimated models. Investigated structures are plates, fuselage panels and helicopter main rotor blades as they represent different complexity levels ranging from coupon, through sub-component up to fully assembled structures made of composite materials. To evaluate...

  12. Structural Materials and Fuels for Space Power Plants

    Science.gov (United States)

    Bowman, Cheryl; Busby, Jeremy; Porter, Douglas

    2008-01-01

    A fission reactor combined with Stirling convertor power generation is one promising candidate in on-going Fission Surface Power (FSP) studies for future lunar and Martian bases. There are many challenges for designing and qualifying space-rated nuclear power plants. In order to have an affordable and sustainable program, NASA and DOE designers want to build upon the extensive foundation in nuclear fuels and structural materials. This talk will outline the current Fission Surface Power program and outline baseline design options for a lunar power plant with an emphasis on materials challenges. NASA first organized an Affordable Fission Surface Power System Study Team to establish a reference design that could be scrutinized for technical and fiscal feasibility. Previous papers and presentations have discussed this study process in detail. Considerations for the reference design included that no significant nuclear technology, fuels, or material development were required for near term use. The desire was to build upon terrestrial-derived reactor technology including conventional fuels and materials. Here we will present an overview of the reference design, Figure 1, and examine the materials choices. The system definition included analysis and recommendations for power level and life, plant configuration, shielding approach, reactor type, and power conversion type. It is important to note that this is just one concept undergoing refinement. The design team, however, understands that materials selection and improvement must be an integral part of the system development.

  13. TRADITIONAL METALLURGY, NANOTECHNOLOGIES AND STRUCTURAL MATERIALS: A SORBY AWARD LECTURE

    Energy Technology Data Exchange (ETDEWEB)

    Louthan, M

    2007-07-17

    Traditional metallurgical processes are among the many ''old fashion'' practices that use nanoparticles to control the behavior of materials. Many of these practices were developed long before microscopy could resolve nanoscale features, yet the practitioners learned to manipulate and control microstructural elements that they could neither see nor identify. Furthermore, these early practitioners used that control to modify microstructures and develop desired material properties. Centuries old colored glass, ancient high strength steels and medieval organ pipes derived many of their desirable features through control of nanoparticles in their microstructures. Henry Sorby was among the first to recognize that the properties of rocks, minerals, metals and organic materials were controlled by microstructure. However, Mr. Sorby was accused of the folly of trying to study mountains with a microscope. Although he could not resolve nanoscale microstructural features, Mr. Sorby's observations revolutionized the study of materials. The importance of nanoscale microstructural elements should be emphasized, however, because the present foundation for structural materials was built by manipulating those features. That foundation currently supports several multibillion dollar industries but is not generally considered when the nanomaterials revolution is discussed. This lecture demonstrates that using nanotechnologies to control the behavior of metallic materials is almost as old as the practice of metallurgy and that many of the emergent nanomaterials technologists are walking along pathways previously paved by traditional metallurgists.

  14. Fiber Optic Thermal Health Monitoring of Aerospace Structures and Materials

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.; Allison, Sidney G.

    2009-01-01

    A new technique is presented for thermographic detection of flaws in materials and structures by performing temperature measurements with fiber Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of structures with subsurface defects or thickness variations. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. The data obtained from grating sensors were further analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with those from conventional thermography techniques. Limitations of the technique were investigated using both experimental and numerical simulation techniques. Methods for performing in-situ structural health monitoring are discussed.

  15. Nanomanufacturing : nano-structured materials made layer-by-layer.

    Energy Technology Data Exchange (ETDEWEB)

    Cox, James V.; Cheng, Shengfeng; Grest, Gary Stephen; Tjiptowidjojo, Kristianto (University of New Mexico); Reedy, Earl David, Jr.; Fan, Hongyou; Schunk, Peter Randall; Chandross, Michael Evan; Roberts, Scott A.

    2011-10-01

    Large-scale, high-throughput production of nano-structured materials (i.e. nanomanufacturing) is a strategic area in manufacturing, with markets projected to exceed $1T by 2015. Nanomanufacturing is still in its infancy; process/product developments are costly and only touch on potential opportunities enabled by growing nanoscience discoveries. The greatest promise for high-volume manufacturing lies in age-old coating and imprinting operations. For materials with tailored nm-scale structure, imprinting/embossing must be achieved at high speeds (roll-to-roll) and/or over large areas (batch operation) with feature sizes less than 100 nm. Dispersion coatings with nanoparticles can also tailor structure through self- or directed-assembly. Layering films structured with these processes have tremendous potential for efficient manufacturing of microelectronics, photovoltaics and other topical nano-structured devices. This project is designed to perform the requisite R and D to bring Sandia's technology base in computational mechanics to bear on this scale-up problem. Project focus is enforced by addressing a promising imprinting process currently being commercialized.

  16. Structural integrity of engineering composite materials: a cracking good yarn

    Science.gov (United States)

    Beaumont, Peter W. R.

    2016-01-01

    Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Where human life depends upon engineering ingenuity, the burden of testing to prove a ‘fracture safe design’ is immense. Fitness considerations for long-life implementation of large composite structures include understanding phenomena such as impact, fatigue, creep and stress corrosion cracking that affect reliability, life expectancy and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined, and takes service duty into account. However, there are conflicting aims in the complete design process of designing simultaneously for high efficiency and safety assurance throughout an economically viable lifetime with an acceptable level of risk. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’. PMID:27242293

  17. Application of fracture mechanics to materials and structures

    Energy Technology Data Exchange (ETDEWEB)

    Sih, G.C.; Sommer, E.; Dahl, W.

    1984-01-01

    The general theme is the interplay between material and design requirements, and this was underlined in many of the technical presentations. A panel discussion further clarified the objectives of fracture mechanics as a discipline and tool to guard structural and machine components against premature failure. Numerical and experimental techniques were shown to be essential in compiling laboratory data on fracture testing, and the need for the development of rational procedures to ensure safety and reliability in the design of modern structures was very strongly emphasized.

  18. Some Material Characteristics of Cold-Sprayed Structures

    Directory of Open Access Journals (Sweden)

    Victor K. Champagne

    2007-01-01

    Full Text Available The deposition and consolidation of metal powders by means of cold spray are methods whereby powder particles are accelerated to high velocity through entrainment in a gas undergoing expansion in a rocket nozzle and are subsequently impacted upon a surface. The impacted powder particles form a consolidated structure which can be several centimeters thick. The characteristics of this structure depend on the initial characteristics of the metal powder and upon impact velocity. The influence of impact velocity on strain hardening and porosity are examined. A materials model is proposed for these phenomena, and model calculation is compared with experiment for the cold spraying of aluminum.

  19. Structure/property relationships in non-linear optical materials

    Energy Technology Data Exchange (ETDEWEB)

    Cole, J.M. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)]|[Durham Univ. (United Kingdom); Howard, J.A.K. [Durham Univ. (United Kingdom); McIntyre, G.J. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    The application of neutrons to the study of structure/property relationships in organic non-linear optical materials (NLOs) is described. In particular, charge-transfer effects and intermolecular interactions are investigated. Charge-transfer effects are studied by charge-density analysis and an example of one such investigation is given. The study of intermolecular interactions concentrates on the effects of hydrogen-bonding and an example is given of two structurally similar molecules with very disparate NLO properties, as a result of different types of hydrogen-bonding. (author). 3 refs.

  20. Structural features of carbon materials synthesized by different methods

    Science.gov (United States)

    Streletskii, O. A.; Ivanenko, I. P.; Khvostov, V. V.; Savchenko, N. F.; Nishchak, O. Yu.; Aleksandrov, A. F.

    2016-10-01

    This paper presents the results of investigations of three types of carbon structures synthesized by different methods, such as arc discharge plasma enhanced chemical vapor deposition of carbon in a magnetic field, chemical dehydrohalogenation of the poly(vinyl chloride)/poly(vinylidene chloride) precursor, and pulsed plasma ion assisted deposition. It has been found that the samples prepared by different methods have a common feature, i.e., the presence of three-dimensional clusters based on sp 2- or sp 3-bonds surrounded by quasi-one-dimensional carbon chains. It has been shown that the structure of carbon materials changes depending on the synthesis conditions.

  1. Structure-property relationships in silica-siloxane nanocomposite materials

    Energy Technology Data Exchange (ETDEWEB)

    Ulibarri, T.A.; Derzon, D.K.; Wang, L.C.

    1997-03-01

    The simultaneous formation of a filler phase and a polymer matrix via in situ sol-gel techniques provides silica-siloxane nanocomposite materials of high strength. This study concentrates on the effects of temperature and relative humidity on a trimodal polymer system in an attempt to accelerate the reaction as well as evaluate subtle process- structure-property relations. It was found that successful process acceleration is only viable for high humidity systems when using the tin(IV) catalyst dibutyltin dilaurate. Processes involving low humidity were found to be very temperature and time dependent. Bimodal systems were investigated and demonstrated that the presence of a short-chain component led to enhanced material strength. This part of the study also revealed a link between the particle size and population density and the optimization of material properties.

  2. Use of UHPC in Bridge Structures: Material Modeling and Design

    Directory of Open Access Journals (Sweden)

    Oguz Gunes

    2012-01-01

    Full Text Available Ultra-high-performance concrete (UHPC is a promising new class of concrete material that is likely to make a significant contribution to addressing the challenges associated with the load capacity, durability, sustainability, economy, and environmental impact of concrete bridge infrastructures. This paper focuses on the material modeling of UHPC and design of bridge girders made of UHPC. A two-phase model used for modeling the behavior of UHPC was briefly discussed, and the model was implemented in a preliminary design case study. Based on the implemented design and the reported use of UHPC in bridge applications, the advantages, limitations, and future prospects of UHPC bridges were discussed, highlighting the need for innovative research and design to make optimum use of the favorable properties of the material in bridge structures.

  3. Innovative Structural Materials and Sections with Strain Hardening Cementitious Composites

    Science.gov (United States)

    Dey, Vikram

    The motivation of this work is based on development of new construction products with strain hardening cementitious composites (SHCC) geared towards sustainable residential applications. The proposed research has three main objectives: automation of existing manufacturing systems for SHCC laminates; multi-level characterization of mechanical properties of fiber, matrix, interface and composites phases using servo-hydraulic and digital image correlation techniques. Structural behavior of these systems were predicted using ductility based design procedures using classical laminate theory and structural mechanics. SHCC sections are made up of thin sections of matrix with Portland cement based binder and fine aggregates impregnating continuous one-dimensional fibers in individual or bundle form or two/three dimensional woven, bonded or knitted textiles. Traditional fiber reinforced concrete (FRC) use random dispersed chopped fibers in the matrix at a low volume fractions, typically 1-2% to avoid to avoid fiber agglomeration and balling. In conventional FRC, fracture localization occurs immediately after the first crack, resulting in only minor improvement in toughness and tensile strength. However in SHCC systems, distribution of cracking throughout the specimen is facilitated by the fiber bridging mechanism. Influence of material properties of yarn, composition, geometry and weave patterns of textile in the behavior of laminated SHCC skin composites were investigated. Contribution of the cementitious matrix in the early age and long-term performance of laminated composites was studied with supplementary cementitious materials such as fly ash, silica fume, and wollastonite. A closed form model with classical laminate theory and ply discount method, coupled with a damage evolution model was utilized to simulate the non-linear tensile response of these composite materials. A constitutive material model developed earlier in the group was utilized to characterize and

  4. Geometric and material nonlinear analysis of tensegrity structures

    Institute of Scientific and Technical Information of China (English)

    Hoang Chi Tran; Jaehong Lee

    2011-01-01

    A numerical method is presented for the large deflection in elastic analysis of tensegrity structures including both geometric and material nonlinearities.The geometric nonlinearity is considered based on both total Lagrangian and updated Lagrangian formulations,while the material nonlinearity is treated through elastoplastic stressstrain relationship.The nonlinear equilibrium equations are solved using an incremental-iterative scheme in conjunction with the modified Newton-Raphson method.A computer program is developed to predict the mechanical responses of tensegrity systems under tensile,compressive and flexural loadings.Numerical results obtained are compared with those reported in the literature to demonstrate the accuracy and efficiency of the proposed program.The flexural behavior of the double layer quadruplex tensegrity grid is sufficiently good for lightweight large-span structural applications.On the other hand,its bending strength capacity is not sensitive to the self-stress level.

  5. Controllability and reliability issues related to electrorheological material adaptive structures

    Energy Technology Data Exchange (ETDEWEB)

    Shiang, A.; Coulter, J. [Lehigh Univ., Bethlehem, PA (United States). Mechanical Engineering and Mechanics--Packard Lab.

    1994-12-31

    The present investigation focused on the controllability and reliability of an electrorheological (ER) material filled adaptive beam. An AC ER material-filled composite beam was constructed and tested over a period of 500 hours. Attention was focused on changes in fundamental vibration frequencies and modal loss factor over the test period. Controllability in terms of beam vibration response time to both increasing and decreasing field strengths was also studied. Response times at the first two fundamental frequencies of 15 and 35 Hertz were focused on. The results indicated that at 35 Hertz, the structural response time was faster for both switching on and switching off of the electric field. In switching off the electric field, the structure returned to zero-field behavior within three seconds on all occasions. The duration of the electric field application did not affect beam response time.

  6. Welcome to the 2014 volume of Smart Materials and Structures

    Science.gov (United States)

    Garcia, Ephrahim

    2014-01-01

    Welcome to Smart Materials and Structures (SMS). Smart materials and structures are comprised of structural matter that responds to a stimulus. These materials can be controlled or have properties that can be altered in a prescribed manner. Smart materials generate non-traditional forms of transduction. We are all familiar with common forms of transduction, electromechanical motors. Lorenz's forces utilize permanent and variable magnets, controlled by current, to generate magnetically generated forces that oppose each other. Utilizing this simple principal we have advanced the industrial revolution of the 19th Century by the creation of the servo-mechanism. Controlled velocity and position generation systems that have automated manufacturing, our machines and the very environs in which we dwell. Smart materials often rely on a variety of new and different methods of transduction. Piezoelectric, magnetostrictive, electrostrictive, and phase-change materials, such as shape memory alloys, are among the most common smart materials. Other approaches such as polymer actuators that rely on complex three-dimensional chemical-based composites are also emerging. The trinity of engineering research is analysis, simulation and experimentation. To perform analyses we must understand the physical phenomena at hand in order to develop a mathematical model for the problem. These models form the basis of simulation and complex computational modeling of a system. It is from these models that we begin to expand our understanding about what is possible, ultimately developing simulation-based tools that verify new designs and insights. Experimentation offers the opportunity to verify our analyses and simulations in addition to providing the 'proof of the pudding' so to speak. But it is our ability to simulate that guides us and our expectations, predicting the behavior of what we may see in the lab or in a prototype. Experimentation ultimately provides the feedback to our modeling

  7. Neutron Cross Section Covariances for Structural Materials and Fission Products

    Science.gov (United States)

    Hoblit, S.; Cho, Y.-S.; Herman, M.; Mattoon, C. M.; Mughabghab, S. F.; Obložinský, P.; Pigni, M. T.; Sonzogni, A. A.

    2011-12-01

    We describe neutron cross section covariances for 78 structural materials and fission products produced for the new US evaluated nuclear reaction library ENDF/B-VII.1. Neutron incident energies cover full range from 10 eV to 20 MeV and covariances are primarily provided for capture, elastic and inelastic scattering as well as (n,2n). The list of materials follows priorities defined by the Advanced Fuel Cycle Initiative, the major application being data adjustment for advanced fast reactor systems. Thus, in addition to 28 structural materials and 49 fission products, the list includes also 23Na which is important fast reactor coolant. Due to extensive amount of materials, we adopted a variety of methodologies depending on the priority of a specific material. In the resolved resonance region we primarily used resonance parameter uncertainties given in Atlas of Neutron Resonances and either applied the kernel approximation to propagate these uncertainties into cross section uncertainties or resorted to simplified estimates based on integral quantities. For several priority materials we adopted MF32 covariances produced by SAMMY at ORNL, modified by us by adding MF33 covariances to account for systematic uncertainties. In the fast neutron region we resorted to three methods. The most sophisticated was EMPIRE-KALMAN method which combines experimental data from EXFOR library with nuclear reaction modeling and least-squares fitting. The two other methods used simplified estimates, either based on the propagation of nuclear reaction model parameter uncertainties or on a dispersion analysis of central cross section values in recent evaluated data files. All covariances were subject to quality assurance procedures adopted recently by CSEWG. In addition, tools were developed to allow inspection of processed covariances and computed integral quantities, and for comparing these values to data from the Atlas and the astrophysics database KADoNiS.

  8. Neutron Cross Section Covariances for Structural Materials and Fission Products

    Energy Technology Data Exchange (ETDEWEB)

    Hoblit, S.; Hoblit,S.; Cho,Y.-S.; Herman,M.; Mattoon,C.M.; Mughabghab,S.F.; Oblozinsky,P.; Pigni,M.T.; Sonzogni,A.A.

    2011-12-01

    We describe neutron cross section covariances for 78 structural materials and fission products produced for the new US evaluated nuclear reaction library ENDF/B-VII.1. Neutron incident energies cover full range from 10{sup -5} eV to 20 MeV and covariances are primarily provided for capture, elastic and inelastic scattering as well as (n,2n). The list of materials follows priorities defined by the Advanced Fuel Cycle Initiative, the major application being data adjustment for advanced fast reactor systems. Thus, in addition to 28 structural materials and 49 fission products, the list includes also {sup 23}Na which is important fast reactor coolant. Due to extensive amount of materials, we adopted a variety of methodologies depending on the priority of a specific material. In the resolved resonance region we primarily used resonance parameter uncertainties given in Atlas of Neutron Resonances and either applied the kernel approximation to propagate these uncertainties into cross section uncertainties or resorted to simplified estimates based on integral quantities. For several priority materials we adopted MF32 covariances produced by SAMMY at ORNL, modified by us by adding MF33 covariances to account for systematic uncertainties. In the fast neutron region we resorted to three methods. The most sophisticated was EMPIRE-KALMAN method which combines experimental data from EXFOR library with nuclear reaction modeling and least-squares fitting. The two other methods used simplified estimates, either based on the propagation of nuclear reaction model parameter uncertainties or on a dispersion analysis of central cross section values in recent evaluated data files. All covariances were subject to quality assurance procedures adopted recently by CSEWG. In addition, tools were developed to allow inspection of processed covariances and computed integral quantities, and for comparing these values to data from the Atlas and the astrophysics database KADoNiS.

  9. Development of fuels and structural materials for fast breeder reactors

    Indian Academy of Sciences (India)

    Baldev Raj; S L Mannan; P R Vasudeva Rao; M D Mathew

    2002-10-01

    Fast breeder reactors (FBRs) are destined to play a crucial role inthe Indian nuclear power programme in the foreseeable future. FBR technology involves a multi-disciplinary approach to solve the various challenges in the areas of fuel and materials development. Fuels for FBRs have significantly higher concentration of fissile material than in thermal reactors, with a matching increase in burn-up. The design of the fuel is an important aspect which has to be optimised for efficient, economic and safe production of power. FBR components operate under hostile and demanding environment of high neutron flux, liquid sodium coolant and elevated temperatures. Resistance to void swelling, irradiation creep, and irradiation embrittlement are therefore major considerations in the choice of materials for the core components. Structural and steam generator materials should have good resistance to creep, low cycle fatigue, creep-fatigue interaction and sodium corrosion. The development of carbide fuel and structural materials for the Fast Breeder Test Reactor at Kalpakkam was a great technological challenge. At the Indira Gandhi Centre for Atomic Research (IGCAR), advanced research facilities have been established, and extensive studies have been carried out in the areas of fuel and materials development. This has laid the foundation for the design and development of a 500 MWe Prototype Fast Breeder Reactor. Highlights of some of these studies are discussed in this paper in the context of our mission to develop and deploy FBR technology for the energy security of India in the 21st century.

  10. Electromagnetic wave propagation in alternating material-metamaterial layered structures

    CERN Document Server

    Carrera-Escobedo, V H

    2016-01-01

    Using the transfer matrix method, we examine the parametric behavior of the transmittance of an electromagnetic plane wave propagating in the lossless regime through a periodic multilayered system as a function of the frequency and angle of incidence of the electromagnetic wave for the case in which the periodic structure comprises alternating material-metamaterial layers. A specific example of high transmittance at any angle of incidence in the visible region of the spectrum is identified

  11. Health sociology from post-structuralism to the new materialisms.

    Science.gov (United States)

    Fox, Nick J

    2016-01-01

    The article reviews the impact of post-structuralism and postmodern social theory upon health sociology during the past 20 years. It then addresses the emergence of new materialist perspectives, which to an extent build upon insights of post-structuralist concerning power, but mark a turn away from a textual or linguistic focus to address the range of materialities that affect health, illness and health care. I conclude by assessing the impact of these movements for health sociology.

  12. Target and structural materials under dual-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Camus, E.; Wanderka, N.; Wollenberger, H. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1995-11-01

    The European Spallation Source (ESS) is planned to have a beam power of 5 MW (3.75 mA of 1.334 GeV protons). This is by a factor 30 higher than the available most powerful spallation source ISIS at Rutherford-Appleton Lab. (RAL) in Great-Britain. This causes a damage rate of approx. 10 dpa (displacements per atom) per month in target materials (W or Ta) or structural materials. The problem of radiation damage by high energy protons in different alloys has been recently reviewed. At HMI, simulation irradiation using heavy ions and helium or hydrogen ions at the dual-beam facility are being out. Here, we report on some preliminary results obtained on tantalum as target material and on ferritic/martensitic steels (HT9 type steels or comparable steels), which are proposed to be used as structural materials. Goal of these investigations is to correlate the results with those obtained at spallation irradiated specimens and to investigate the unexplored field of simultaneous production of damage, helium and hydrogen at high levels. (author) 4 figs., 1 tab., 9 refs.

  13. New materials for structural restoration: an old debate

    Directory of Open Access Journals (Sweden)

    Federica Ottoni

    2015-12-01

    Full Text Available The use of composites in architectural restoration is becoming more and more widespread, due to their technical advantages, in many cases. However, using these materials in the field of cultural heritage creates not only technical problems but also cultural issues. The paper deals with these issues, starting from some considerations on the use of “new” materials in the past, when – just to mention some examples – iron, steel and reinforced concrete were considered innovative. From Ruskin’s idea of  “crutch”, passing to the “hidden reinforcement” expressed in the Athens Charter, to some more recent examples, the past experiences offer once again the opportunity to evaluate new techniques and theoretical approaches. The authors underline the opportunity to identify a “correct methodology” rather than a “correct solution” in restoration.  Further knowledge and comprehension of a monument and – at the same time - a deep awareness of the limits and weaknesses of recent technologies and materials, may guide architects to a more efficient, respectful structural restoration project. Keywords: restoration, structure, materials, reinforcement, technique

  14. New smart materials to address issues of structural health monitoring.

    Energy Technology Data Exchange (ETDEWEB)

    Chaplya, Pavel Mikhail

    2004-12-01

    Nuclear weapons and their storage facilities may benefit from in-situ structural health monitoring systems. Appending health-monitoring functionality to conventional materials and structures has been only marginally successful. The purpose of this project was to evaluate feasibility of a new smart material that includes self-sensing health monitoring functions similar to that of a nervous system of a living organism. Reviews of current efforts in the fields of heath-monitoring, nanotechnology, micro-electromechanical systems (MEMS), and wireless sensor networks were conducted. Limitations of the current nanotechnology methods were identified and new approaches were proposed to accelerate the development of self-sensing materials. Wireless networks of MEMS sensors have been researched as possible prototypes of self-sensing materials. Sensor networks were also examined as enabling technologies for dense data collection techniques to be used for validation of numerical methods and material parameter identification. Each grain of the envisioned material contains sensors that are connected in a dendritic manner similar to networks of neurons in a nervous system. Each sensor/neuron can communicate with the neighboring grains. Both the state of the sensor (on/off) and the quality of communication signal (speed/amplitude) should indicate not only a presence of a structural defect but the nature of the defect as well. For example, a failed sensor may represent a through-grain crack, while a lost or degraded communication link may represent an inter-granular crack. A technology to create such material does not exist. While recent progress in the fields of MEMS and nanotechnology allows to envision these new smart materials, it is unrealistic to expect creation of self-sensing materials in the near future. The current state of MEMS, nanotechnology, communication, sensor networks, and data processing technologies indicates that it will take more than ten years for the

  15. Oxide Thermoelectric Materials: A Structure-Property Relationship

    Science.gov (United States)

    Nag, Abanti; Shubha, V.

    2014-04-01

    Recent demand for thermoelectric materials for power harvesting from automobile and industrial waste heat requires oxide materials because of their potential advantages over intermetallic alloys in terms of chemical and thermal stability at high temperatures. Achievement of thermoelectric figure of merit equivalent to unity ( ZT ≈ 1) for transition-metal oxides necessitates a second look at the fundamental theory on the basis of the structure-property relationship giving rise to electron correlation accompanied by spin fluctuation. Promising transition-metal oxides based on wide-bandgap semiconductors, perovskite and layered oxides have been studied as potential candidate n- and p-type materials. This paper reviews the correlation between the crystal structure and thermoelectric properties of transition-metal oxides. The crystal-site-dependent electronic configuration and spin degeneracy to control the thermopower and electron-phonon interaction leading to polaron hopping to control electrical conductivity is discussed. Crystal structure tailoring leading to phonon scattering at interfaces and nanograin domains to achieve low thermal conductivity is also highlighted.

  16. Characterization of ion-exchange membrane materials: properties vs structure.

    Science.gov (United States)

    Berezina, N P; Kononenko, N A; Dyomina, O A; Gnusin, N P

    2008-06-22

    This review focuses on the preparation, structure and applications of ion-exchange membranes formed from various materials and exhibiting various functions (electrodialytic, perfluorinated sulphocation-exchange and novel laboratory-tested membranes). A number of experimental techniques for measuring electrotransport properties as well as the general procedure for membrane testing are also described. The review emphasizes the relationships between membrane structures, physical and chemical properties and mechanisms of electrochemical processes that occur in charged membrane materials. The water content in membranes is considered to be a key factor in the ion and water transfer and in polarization processes in electromembrane systems. We suggest the theoretical approach, which makes it possible to model and characterize the electrochemical properties of heterogeneous membranes using several transport-structural parameters. These parameters are extracted from the experimental dependences of specific electroconductivity and diffusion permeability on concentration. The review covers the most significant experimental and theoretical research on ion-exchange membranes that have been carried out in the Membrane Materials Laboratory of the Kuban State University. These results have been discussed at the conferences "Membrane Electrochemistry", Krasnodar, Russia for many years and were published mainly in Russian scientific sources.

  17. Code qualification of structural materials for AFCI advanced recycling reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Li, M.; Majumdar, S.; Nanstad, R.K.; Sham, T.-L. (Nuclear Engineering Division); (ORNL)

    2012-05-31

    This report summarizes the further findings from the assessments of current status and future needs in code qualification and licensing of reference structural materials and new advanced alloys for advanced recycling reactors (ARRs) in support of Advanced Fuel Cycle Initiative (AFCI). The work is a combined effort between Argonne National Laboratory (ANL) and Oak Ridge National Laboratory (ORNL) with ANL as the technical lead, as part of Advanced Structural Materials Program for AFCI Reactor Campaign. The report is the second deliverable in FY08 (M505011401) under the work package 'Advanced Materials Code Qualification'. The overall objective of the Advanced Materials Code Qualification project is to evaluate key requirements for the ASME Code qualification and the Nuclear Regulatory Commission (NRC) approval of structural materials in support of the design and licensing of the ARR. Advanced materials are a critical element in the development of sodium reactor technologies. Enhanced materials performance not only improves safety margins and provides design flexibility, but also is essential for the economics of future advanced sodium reactors. Code qualification and licensing of advanced materials are prominent needs for developing and implementing advanced sodium reactor technologies. Nuclear structural component design in the U.S. must comply with the ASME Boiler and Pressure Vessel Code Section III (Rules for Construction of Nuclear Facility Components) and the NRC grants the operational license. As the ARR will operate at higher temperatures than the current light water reactors (LWRs), the design of elevated-temperature components must comply with ASME Subsection NH (Class 1 Components in Elevated Temperature Service). However, the NRC has not approved the use of Subsection NH for reactor components, and this puts additional burdens on materials qualification of the ARR. In the past licensing review for the Clinch River Breeder Reactor Project (CRBRP

  18. Photonic materials, structures and devices for Reststrahlen optics.

    Science.gov (United States)

    Feng, K; Streyer, W; Zhong, Y; Hoffman, A J; Wasserman, D

    2015-11-30

    We present a review of existing and potential next-generation far-infrared (20-60 μm) optical materials and devices. The far-infrared is currently one of the few remaining frontiers on the optical spectrum, a space underdeveloped and lacking in many of the optical and optoelectronic materials and devices taken for granted in other, more technologically mature wavelength ranges. The challenges associated with developing optical materials, structures, and devices at these wavelengths are in part a result of the strong phonon absorption in the Reststrahlen bands of III-V semiconductors that collectively span the far-infrared. More than just an underexplored spectral band, the far-IR may also be of potential importance for a range of sensing applications in astrochemistry, biology, and industrial and geological processes. Additionally, with a suitable far-IR optical infrastructure, it is conceivable that even more applications could emerge. In this review, we will present recent progress on far-infrared materials and phenomena such as phononic surface modes, engineered composite materials, and optoelectronic devices that have the potential to serve as the next generation of components in a far-infrared optical tool-kit.

  19. Protection and Reinforcement of Tooth Structures by Dental Coating Materials

    Directory of Open Access Journals (Sweden)

    Toru Nikaido

    2012-10-01

    Full Text Available It has been proposed that a resin coating can serve as a means to protect dental structure after preparation of the tooth for indirect restorations, sealing the exposed dentin. The resin coating is applied on the cut surfaces immediately after tooth preparation and before making an impression by assembling a dentin bonding system and a flowable composite. Resin coatings minimize pulp irritation and improve the bond strength between a resin cement and tooth when bonding the restoration to tooth. Recently, thin-film coating dental materials based on all-in-one adhesive technology were introduced for resin coating of indirect restorations. The thin coating materials are applied in a single clinical step and create a barrier-like film layer on the prepared dentin. The thin coatings play an important role in protecting the dentin from physical, chemical, and biological irritation. In addition, these thin-film coating materials reportedly prevent marginal leakage beneath inlays or crown restorations. In light of the many benefits provided by such a protective layer, these all-in-one adhesive materials may therefore also have the potential to cover exposed root dentin surfaces and prevent caries formation. In this paper, recent progress of the dental coating materials and their clinical applications are reviewed.

  20. Modeling of oxidation of structural materials in LBE systems

    Science.gov (United States)

    Steiner, H.; Schroer, C.; Voß, Z.; Wedemeyer, O.; Konys, J.

    2008-02-01

    In recent years, liquid metal alloys have been examined in the light of various applications in technical systems the most famous example is the sodium cooled Fast Breeder Reactor. One major problem in non-isothermal heavy liquid metal systems lies in the corrosion of their structural components. The formation of oxide scales on the structural components is considered as a viable measure in limiting the dissolution rates in the hot parts in lead and lead-bismuth loops. Models for oxide scale growth under the action of flowing liquid metals have been implemented in the newly developed code MATLIM, which allow calculating the evolution of the oxide scales on structural materials in multi-modular loops. There are thermo-hydraulic limitations on oxygen supply from the liquid metal to the structural materials, the oxygen mass transfer coefficient in the liquid metal, which depends on the flow conditions, being rate-determining. This seems to explain, for example, why in the first stage of oxidation of stainless steels slowly growing, dense single layer Fe/Cr spinel scales are formed.

  1. The use of advanced materials in space structure applications

    Science.gov (United States)

    Eaton, D. C. G.; Slachmuylders, E. J.

    The last decade has seen the Space applications of composite materials become almost commonplace in the construction of configurations requiring high stiffness and/or dimensional stability, particularly in the field of antennas. As experience has been accumulated, applications for load carrying structures utilizing the inherent high specific strength/stiffness of carbon fibres have become more frequent. Some typical examples of these and their design development criteria are reviewed. As these structures and the use of new plastic matrices emerge, considerable attention has to be given to establishing essential integrity control requirements from both safety and cost aspects. The advent of manned European space flight places greater emphasis on such requirements. Attention is given to developments in the fields of metallic structures with discussion of the advantages and disadvantages of their application. The design and development of hot structures, thermal protection systems and air-breathing engines for future launch vehicles necessitates the use of the emerging metal/matrix and other advanced materials. Some of their important features are outlined. Means of achieving such objectives by greater harmonization within Europe are emphasized. Typical examples of on-going activities to promote such collaboration are described.

  2. First-principles structural design of superhard materials.

    Science.gov (United States)

    Zhang, Xinxin; Wang, Yanchao; Lv, Jian; Zhu, Chunye; Li, Qian; Zhang, Miao; Li, Quan; Ma, Yanming

    2013-03-21

    We reported a developed methodology to design superhard materials for given chemical systems under external conditions (here, pressure). The new approach is based on the CALYPSO algorithm and requires only the chemical compositions to predict the hardness vs. energy map, from which the energetically preferable superhard structures are readily accessible. In contrast to the traditional ground state structure prediction method where the total energy was solely used as the fitness function, here we adopted hardness as the fitness function in combination with the first-principles calculation to construct the hardness vs. energy map by seeking a proper balance between hardness and energy for a better mechanical description of given chemical systems. To allow a universal calculation on the hardness for the predicted structure, we have improved the earlier hardness model based on bond strength by applying the Laplacian matrix to account for the highly anisotropic and molecular systems. We benchmarked our approach in typical superhard systems, such as elemental carbon, binary B-N, and ternary B-C-N compounds. Nearly all the experimentally known and most of the earlier theoretical superhard structures have been successfully reproduced. The results suggested that our approach is reliable and can be widely applied into design of new superhard materials.

  3. Superamphiphobic overhang structured coating on a biobased material

    Science.gov (United States)

    Tuominen, Mikko; Teisala, Hannu; Haapanen, Janne; Mäkelä, Jyrki M.; Honkanen, Mari; Vippola, Minnamari; Bardage, Stig; Wålinder, Magnus E. P.; Swerin, Agne

    2016-12-01

    A superamphiphobic coating on a biobased material shows extreme liquid repellency with static contact angles (CA) greater than 150° and roll-off angles less than 10° against water, ethylene glycol, diiodomethane and olive oil, and a CA for hexadecane greater than 130°. The coating consisting of titania nanoparticles deposited by liquid flame spray (LFS) and hydrophobized using plasma-polymerized perfluorohexane was applied to a birch hardwood. Scanning electron microscopy (SEM) imaging after sample preparation by UV laser ablation of coated areas revealed that capped structures were formed and this, together with the geometrically homogeneous wood structure, fulfilled the criteria for overhang structures to occur. The coating showed high hydrophobic durability by still being non-wetted after 500 000 water drop impacts, and this is discussed in relation to geometrical factors and wetting forces. The coating was semi-transparent with no significant coloration. A self-cleaning effect was demonstrated with both water and oil droplets. A self-cleanable, durable and highly transparent superamphiphobic coating based on a capped overhang structure has a great potential for commercial feasibility in a variety of applications, here exemplified for a biobased material.

  4. Structured Light-Matter Interactions Enabled By Novel Photonic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Litchinitser, Natalia [Univ. at Buffalo, NY (United States); Feng, Liang [Univ. at Buffalo, NY (United States)

    2017-05-02

    The synergy of complex materials and complex light is expected to add a new dimension to the science of light and its applications [1]. The goal of this program is to investigate novel phenomena emerging at the interface of these two branches of modern optics. While metamaterials research was largely focused on relatively “simple” linearly or circularly polarized light propagation in “complex” nanostructured, carefully designed materials with properties not found in nature, many singular optics studies addressed “complex” structured light transmission in “simple” homogeneous, isotropic, nondispersive transparent media, where both spin and orbital angular momentum are independently conserved. However, if both light and medium are complex so that structured light interacts with a metamaterial whose optical materials properties can be designed at will, the spin or angular momentum can change, which leads to spin-orbit interaction and many novel optical phenomena that will be studied in the proposed project. Indeed, metamaterials enable unprecedented control over light propagation, opening new avenues for using spin and quantum optical phenomena, and design flexibility facilitating new linear and nonlinear optical properties and functionalities, including negative index of refraction, magnetism at optical frequencies, giant optical activity, subwavelength imaging, cloaking, dispersion engineering, and unique phase-matching conditions for nonlinear optical interactions. In this research program we focused on structured light-matter interactions in complex media with three particularly remarkable properties that were enabled only with the emergence of metamaterials: extreme anisotropy, extreme material parameters, and magneto-electric coupling–bi-anisotropy and chirality.

  5. Real-time probing of structural dynamics in perovskite materials

    Energy Technology Data Exchange (ETDEWEB)

    Elsaesser, Thomas [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin (Germany)

    2009-07-01

    Femtosecond x-ray diffraction probes structural dynamics of solids in real-time and gives insight into reversible geometry changes on atomic length and time scales. After a brief introduction into this field, recent results on the lattice dynamics of ferroelectric SrRuO{sub 3}/PbZr{sub 0.2}Ti{sub 0.8}O{sub 3} superlattice structures and their interplay with the electric polarization of the material are presented. Ultrafast optical generation of mechanical stress allows for switching-off the polarization on a time scale of a few picoseconds. As a second example, magnetostriction in a ferromagnetic SrRuO{sub 3}/SrTiO{sub 3} superlattice structure is analyzed in real time.

  6. Disaster mitigation based on smart structures/materials

    Science.gov (United States)

    Asanuma, H.; Su, J.; Shahinpoor, M.; Felli, F.; Paolozzi, A.; Nejhad, M.; Hihara, L.; Aimmanee, S.; Furuya, Y.; Adachi, K.; Yanaseko, T.

    2016-04-01

    The concept "Disaster Mitigation and Sustainable Engineering" is introduced comprehensively and several examples are shown in this paper. It is emphasized that it can be effectively realized in the field "smart materials and structural systems." As serious disasters may not occur for a long period of time, and the structures for disaster mitigation suffer from vast amount of maintenance cost etc., they are better to be used daily. Their compactness and deploying function are also very useful. In order to demonstrate the concept, two examples having been experimentally tried are introduced, that is, artificial forests and deployable structure based on honeycomb to be used against flooding. Other examples and products in the world are also introduced and future directions are discussed.

  7. Abrasion test of flexible protective materials on hydraulic structures

    Directory of Open Access Journals (Sweden)

    Xin WANG

    2014-01-01

    Full Text Available In this study, several kinds of flexible protective materials sprayed with polyurea elastomers (hereinafter referred to as polyurea elastomer protective material were adopted to meet the abrasion resistance requirement of hydraulic structures, and their abrasion resistances against the water flow with suspended load or bed load were studied systematically through tests. Natural basalt stones were adopted as the abrasive for simulation of the abrasion effect of the water flow with bed load, and test results indicate that the basalt stone is suitable for use in the abrasion resistance test of the flexible protective material. The wear process of the polyurea elastomer protective material is stable, and the wear loss is linear with the time of abrasion. If the wear thickness is regarded as the abrasion resistance evaluation factor, the abrasion resistance of the 351 pure polyurea is about twice those of pure polyurea with a high level of hardness and aliphatic polyurea, and over five times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with suspended load. It is also about 50 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load. Overall, the abrasion resistance of pure polyurea presented a decreasing trend with increasing hardness. Pure polyurea with a Shore hardness of D30 has the best abrasion resistance, which is 60 to 70 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load, and has been recommended, among the five kinds of pure polyurea materials with different hardness, in anti-abrasion protection of hydraulic structures.

  8. Continuation of tailored composite structures of ordered staple thermoplastic material

    Science.gov (United States)

    Santare, Michael H.; Pipes, R. Byron

    1992-01-01

    The search for the cost effective composite structure has motivated the investigation of several approaches to develop composite structure from innovative material forms. Among the promising approaches is the conversion of a planar sheet to components of complex curvature through sheet forming or stretch forming. In both cases, the potential for material stretch in the fiber direction appears to offer a clear advantage in formability over continuous fiber systems. A framework was established which allows the simulation of the anisotropic mechanisms of deformation of long discontinuous fiber laminates wherein the matrix phase is a viscous fluid. Predictions for the effective viscosities of a hyper-anisotropic medium consisting of collimated, discontinuous fibers suspended in viscous matrix were extended to capture the characteristics of typical polymers including non-Newtonian behavior and temperature dependence. In addition, the influence of fiber misorientation was also modeled by compliance averaging to determine ensemble properties for a given orientation distribution. A design tool is presented for predicting the effect of material heterogeneity on the performance of curved composite beams such as those used in aircraft fuselage structures. Material heterogeneity can be induced during manufacturing processes such as sheet forming and stretch forming of thermoplastic composites. This heterogeneity can be introduced in the form of fiber realignment and spreading during the manufacturing process causing radial and tangential gradients in material properties. Two analysis procedures are used to solve the beam problems. The first method uses separate two-dimensional elasticity solutions for the stresses in the flange and web sections of the beam. The separate solutions are coupled by requiring that forces and displacements match section boundaries. The second method uses an approximate Rayleigh-Ritz technique to find the solutions for more complex beams. Analyses

  9. Materials, structures, and devices for high-speed electronics

    Science.gov (United States)

    Woollam, John A.; Snyder, Paul G.

    1992-01-01

    Advances in materials, devices, and instrumentation made under this grant began with ex-situ null ellipsometric measurements of simple dielectric films on bulk substrates. Today highly automated and rapid spectroscopic ellipsometers are used for ex-situ characterization of very complex multilayer epitaxial structures. Even more impressive is the in-situ capability, not only for characterization but also for the actual control of the growth and etching of epitaxial layers. Spectroscopic ellipsometry has expanded from the research lab to become an integral part of the production of materials and structures for state of the art high speed devices. Along the way, it has contributed much to our understanding of the growth characteristics and material properties. The following areas of research are summarized: Si3N4 on GaAs, null ellipsometry; diamondlike carbon films; variable angle spectroscopic ellipsometry (VASE) development; GaAs-AlGaAs heterostructures; Ta-Cu diffusion barrier films on GaAs; GaAs-AlGaAs superlattices and multiple quantum wells; superconductivity; in situ elevated temperature measurements of III-V's; optical constants of thermodynamically stable InGaAs; doping dependence of optical constants of GaAs; in situ ellipsometric studies of III-V epitaxial growth; photothermal spectroscopy; microellipsometry; and Si passivation and Si/SiGe strained-layer superlattices.

  10. Structure-Interaction Effects In Novel Nanostructured Materials

    Science.gov (United States)

    Le, Nam B.

    Recent advances in experimental and computational methods have opened up new directions in graphene fundamental studies. In addition to understanding the basic properties of this material and its quasi-one dimensional structures, significant efforts are devoted to describing their long ranged dispersive interactions. Other two-dimensional materials, such as silicene, germanene, and transition metal dichalcogenides, are also being investigated aiming at finding complementary to graphene systems with other "wonder" properties. The focus of this work is to utilize first principles simulations methods to build our basic knowledge of structure-interaction relations in two-dimensional materials and design their properties. In particular, mechanical folding and extended defects in zigzag and armchair graphene nanoribbons can be used to modulate their electronic and spin polarization characteristics and achieve different stacking patterns. Our simulations concerning zigzag silicene nanoribbons show width-dependent antiferromagnetic-ferromagnetic transitions unlike the case of zigzag graphene nanoribbons, which are always antiferromagnetic. Heterostructures, build by stacking graphene, silicene, and MoS2, are also investigated. It is found that hybridization alters the electronic properties of the individual layers and new flexural and breathing phonon modes display unique behaviors in the heterostructure compositions. Anchored to SiC substrate graphene nanoribbons are also proposed as possible systems to be used in graphene electronics. Our findings are of importance not only for fundamental science, but they could also be used for future experimental developments.

  11. Embrittlement and Flow Localization in Reactor Structural Materials

    Energy Technology Data Exchange (ETDEWEB)

    Xianglin Wu; Xiao Pan; James Stubbins

    2006-10-06

    Many reactor components and structural members are made from metal alloys due, in large part, to their strength and ability to resist brittle fracture by plastic deformation. However, brittle fracture can occur when structural material cannot undergo extensive, or even limited, plastic deformation due to irradiation exposure. Certain irradiation conditions lead to the development of a damage microstructure where plastic flow is limited to very small volumes or regions of material, as opposed to the general plastic flow in unexposed materials. This process is referred to as flow localization or plastic instability. The true stress at the onset of necking is a constant regardless of the irradiation level. It is called 'critical stress' and this critical stress has strong temperature dependence. Interrupted tensile testes of 316L SS have been performed to investigate the microstructure evolution and competing mechanism between mechanic twinning and planar slip which are believed to be the controlling mechanism for flow localization. Deformation twinning is the major contribution of strain hardening and good ductility for low temperatures, and the activation of twinning system is determined by the critical twinning stress. Phases transform and texture analyses are also discussed in this study. Finite element analysis is carried out to complement the microstructural analysis and for the prediction of materaials performance with and without stress concentration and irradiation.

  12. Giant Mechanocaloric Effects in Fluorite-Structured Superionic Materials

    Science.gov (United States)

    Cazorla, Claudio; Errandonea, Daniel

    2016-05-01

    Mechanocaloric materials experience a change in temperature when a mechanical stress is adiabatically applied on them. Thus far, only ferroelectrics and superelastic metallic alloys have been considered as potential mechanocaloric compounds to be exploited in solid-state cooling applications. Here we show that giant mechanocaloric effects occur in hitherto overlooked fast ion conductors (FIC), a class of multicomponent materials in which above a critical temperature, Ts, a constituent ionic species undergoes a sudden increase in mobility. Using first-principles and molecular dynamics simulations, we found that the superionic transition in fluorite-structured FIC, which is characterised by a large entropy increase of the order of 100 J/K*Kg, can be externally tuned with hydrostatic, biaxial or uniaxial stresses. In particular, Ts can be reduced several hundreds of degrees through the application of moderate tensile stresses due to the concomitant drop in the formation energy of Frenkel pair defects. We predict that the adiabatic temperature change in CaF2 and PbF2, two archetypal fluorite-structured FIC, close to their critical points are of the order of 100 and 10 K, respectively. This work advocates that FIC constitute a new family of mechanocaloric materials showing great promise for prospective solid-state refrigeration applications.

  13. Synergetic material and structure optimization yields robust spider web anchorages.

    Science.gov (United States)

    Pugno, Nicola M; Cranford, Steven W; Buehler, Markus J

    2013-08-26

    Millions of years of evolution have adapted spider webs to achieve a range of properties, including the well-known capture of prey, with efficient use of materials. One feature that remains poorly understood is the attachment disc, a network of silk fibers that mechanically anchors a web to its environment. Experimental observations suggest that one possible attachment disc adheres to a substrate through multiple symmetrically branched structures composed of sub-micrometer scale silk fibers. Here, a theoretical model is used to explore the adaptation of the strength of attachment of such an anchorage, and complementary mesoscale simulations are applied to demonstrate a novel mechanism of synergetic material and structural optimization, such that the maximum anchorage strength can be achieved regardless of the initial anchor placement or material type. The optimal delamination (peeling) angle is facilitated by the inherent extensibility of silk, and is attained automatically during the process of delamination. This concept of self-optimizing peeling angle suggests that attachment discs do not require precise placement by the spider, irrespective of adhesion strength. Additional hierarchical branching of the anchorage increases efficiency, where both the delamination force and toughness modulus increase with a splitting of the cross-sectional area.

  14. Structural analysis of bioceramic materials for denture application

    Energy Technology Data Exchange (ETDEWEB)

    Rauf, Nurlaela, E-mail: n-rauf@fmipa.unhas.ac.id; Tahir, Dahlang; Arbiansyah, Muhammad [Dept of Physics, FMIPA-Univ. Hasanuddin Makassar Indonesia (Indonesia)

    2016-03-11

    Structural analysis has been performed on bioceramic materials for denture application by using X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscopy (SEM). XRF is using for analysis chemical composition of raw materials. XRF shows the ratio 1 : 1 : 1 : 1 between feldspar, quartz, kaolin and eggshell, respectively, resulting composition CaO content of 56.78 %, which is similar with natural tooth. Sample preparation was carried out on temperature of 800 °C, 900 °C and 1000 °C. X-ray diffraction result showed that the structure is crystalline with trigonal crystal system for SiO{sub 2} (a=b=4.9134 Å and c=5.4051 Å) and CaH{sub 2}O{sub 2} (a=b=3.5925 Å and c=4.9082 Å). Based on the Scherrer’s equation showed the crystallite size of the highest peak (SiO{sub 2}) increase with increasing the temperature preparation. The highest hardness value (87 kg/mm{sup 2}) and match with the standards of dentin hardness. The surface structure was observed by using SEM also discussed.

  15. Defect Physics of Structural Materials under Extreme Conditions

    Science.gov (United States)

    Stocks, G. Malcolm

    2010-03-01

    ``Crystals are like people: it is the defects in them that make them interesting.'' This oft quoted quip of Sir Charles Frank speaks to the heart of structural alloys. Indeed, the extent to which the collective effects of defects can be manipulated and controlled determines the combination of structural materials properties that underpins modern energy and transportation technologies. Furthermore, the bounds on performance of current structural materials generally result from limitations in our understanding of defects, rather than insurmountable physical principles. I will describe research in the Center for Defect PhysicsfootnotetextThe CDP is an Energy Frontier Research Center (EFRC), DOE Office of Basic Energy Sciences. in three thrust areas: *Fundamental Physics of Defect Formation and Evolution during Irradiation *Fundamental Physics of Defect Interactions during Deformation *Quantum Theory of Defects and Interactions Specifically, I will described ongoing and planned research that is based on the realization that we are on the verge of a new era of ``quantitative measurement'' and ``direct quantum simulation'' of defects and their interactions enabled by major national facilities (APS, SNS, and LCLS) and the PFlop/s computing (NCCS and NERSC).

  16. Development and mechanical properties of structural materials from lunar simulants

    Science.gov (United States)

    Desai, Chandra S.; Girdner, K.; Saadatmanesh, H.; Allen, T.

    1991-01-01

    Development of the technologies for manufacture of structural and construction materials on the Moon, utilizing local lunar soil (regolith), without the use of water, is an important element for habitats and explorations in space. Here, it is vital that the mechanical behavior such as strength and flexural properties, fracture toughness, ductility and deformation characteristics be defined toward establishment of the ranges of engineering applications of the materials developed. The objective is to describe the research results in two areas for the above goal: (1) liquefaction of lunar simulant (at about 100 C) with different additives (fibers, powders, etc.); and (2) development and use of a new triaxial test device in which lunar simulants are first compressed under cycles of loading, and then tested with different vacuums and initial confining or in situ stress.

  17. Direct methods for limit states in structures and materials

    CERN Document Server

    Weichert, Dieter

    2014-01-01

    Knowing the safety factor for limit states such as plastic collapse, low cycle fatigue or ratcheting is always a major design consideration for civil and mechanical engineering structures that are subjected to loads. Direct methods of limit or shakedown analysis that proceed to directly find the limit states offer a better alternative than exact time-stepping calculations as, on one hand, an exact loading history is scarcely known, and on the other they are much less time-consuming. This book presents the state of the art on various topics concerning these methods, such as theoretical advances in limit and shakedown analysis, the development of relevant algorithms and computational procedures, sophisticated modeling of inelastic material behavior like hardening, non-associated flow rules, material damage and fatigue, contact and friction, homogenization and composites.

  18. Structure and Property Characterization of Oyster Shell Cementing Material

    Institute of Scientific and Technical Information of China (English)

    钟彬杨; 周强; 单昌锋; 于岩

    2012-01-01

    Oyster shell powder was used as the admixture of ordinary portland cement.The effects of different addition amounts and grinding ways on the strength and stability of cement mortar were discussed and proper addition amount of oyster shell powder was determined.The structure and property changes of cementing samples with different oyster shell powder contents were tested by XRD and SEM means.The results revealed that compressive and rupture strengths of the sample with 10% oyster shell powder was close to those of the original one without addition.Stability experiment showed that the sample prepared by pat method had smooth surface without crack and significant expansion or shrinkage after pre-curing and boiling,which indicated that cementing material dosed with oyster shell powder had fine stability.XRD and SEM observation showed that oyster shell independently exists in the cementing material.

  19. Hierarchical structuring of liquid crystal polymer-Laponite hybrid materials.

    Science.gov (United States)

    Tritschler, Ulrich; Zlotnikov, Igor; Zaslansky, Paul; Aichmayer, Barbara; Fratzl, Peter; Schlaad, Helmut; Cölfen, Helmut

    2013-09-03

    Biomimetic organic-inorganic composite materials were fabricated via one-step self-organization on three hierarchical levels. The organic component was a polyoxazoline with pendent cholesteryl and carboxyl (N-Boc-protected amino acid) side chains that was able to form a chiral nematic lyotropic phase and bind to positively charged inorganic faces of Laponite. The Laponite particles formed a mesocrystalline arrangement within the liquid-crystal (LC) polymer phase upon shearing a viscous dispersion of Laponite nanoparticles and LC polymer in DMF. Complementary analytical and mechanical characterization techniques (AUC, POM, TEM, SEM, SAXS, μCT, and nanoindentation) covering the millimeter, micrometer, and nanometer length scales reveal the hierarchical structures and properties of the composite materials consisting of different ratios of Laponite nanoparticles and liquid-crystalline polymer.

  20. Ablative thermal management structural material on the hypersonic vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Shortland, H.; Tsai, C. [Rockwell International Corporation, Seal Beach, CA (United States)

    1995-09-01

    A hypersonic vehicle is designed to fly at high Mach number in the earth`s atmosphere that will result in higher aerodynamic heating loads on specific areas of the vehicle. A thermal protection system is required for these areas that may exceed the operating temperature limit of structural materials. This paper delineates the application of ablative material as the passive type of thermal protection system for the nose or wing leading edges. A simplified quasi-steady-state one-dimensional computer model was developed to evaluate the performance and thermal design of a leading edge. The detailed description of the governing mathematical equations and results are presented. This model provides a quantitative information to support the design estimate, performance optimization, and assess preliminary feasibility of using ablation as a design approach.