bluuebunny/crossref_metadata_2025_split huggingface dataset:
Imaging And Spectroscopy Of Nanostructures Through Aberration-Corrected Stem
Authors: Pennycook S. J. , Chisholm M. F. , Lupini A. R. , Borisevich A. , Sohlberg K. , Mcbride J. R. , Rosenthal S. J. , Kumar D. , Franceschetti A. , Rashkeev S. , Wang S. , Pantelides S. T. 
Published: June 2019

SummaryThe aberration-corrected STEM allows nanostructures to be investigated with greater resolution and sensitivity than ever before. Single atom sensitivity is achieved both in imaging and also for spectroscopy, for atoms on surfaces or within the bulk. Nanocrystal size, shape, surface termination, 3D structure and the presence of any defects can be seen with unprecedented ease. The improved sensitivity provides improved input for theory, allowing new insights into nanostructure properties and the origin of their unique functionality. Furthermore, the larger aperture available with aberration-corrected STEM improves the depth resolution dramatically. Nanometer depth resolution can be achieved by simply taking a focal series of images, which may then be reconstructed into a 3D rendering of the material in the same manner as with confocal optical microscopy but maintaining sensitivity to individual atoms.
Controlled Synthesis and Characterization of Co-Au Core-shell Nanoparticles
Authors: Bao Yuping , Calderon Hector , Krishnan Kannan M. 
Published: June 2019

AbstractCo-Au Core-shell nanoparticles are synthesized by slowly reducing an organo-gold compound on pre-made cobalt seeds with a weak reducer at mild condition. For the first time, these coreshell nanoparticles are generated in non-polar solvent in a controlled manner. The formation theory of core-shell structure, especially the seed size effect, is addressed as well. These coreshell structures are confirmed with a wide range of transmission electron microscopy (TEM) methods, which includes routine TEM images, high resolution TEM, and z-contrast imaging.
Size Effect Study of the L10Phase Transformation in FePt Nanoparticles
Authors: Ding Yi , Majetich Sara A. 
Published: June 2019

AbstractThe relation between particle size and anisotropy in the fcc to L10phase transformation in FePt nanoparticles is described. After annealing to partially sinter the particles, the volume distribution was found by transmission electron microscopy, and related to the magnetic switching field distribution. With the assumption that larger particles have higher switching fields, we find a consistent size threshold,d*, of about 12 nm for high anisotropy, independent of the annealing conditions. Our analysis shows that the phase transformation is limited by the lack of nucleation sites in small particles rather than by the chemical inhomogeneity.
Manipulation of Non-Magnetic Materials in Ferrofluid Containing Media
Authors: Halverson Derek , Yellen Ben , Friedman Gary 
Published: June 2019

AbstractA novel method is proposed whereby non-magnetic objects can be moved along a surface at the microscale and nanoscale. It uses a negative magnetophoretic force, explained in the caption for figure one, on the non-magnetic objects which results from stabilized 10nm diameter iron oxide particles (ferrofluid) being attracted to regions of field maxima around magnetic islands on a surface, which pushes the non-magnetic objects to regions of field minima. By varying an external magnetic field we can control where these minima are and thus control how objects will position themselves with static fields and by using rotating time varying fields we can control how they move across the surface. This method does not require the objects to be initially in contact with the surface, as they will be pulled down to the surface from solution. While this paper deals with beads, any arbitrarily shaped object should be manipuable using this method. Additionally, while we address non-magnetic objects in this work similar methods could easily manipulate objects that are magnetic.
Synthesis of Well-aligned ZnO Nanowires Using Simple Physical Vapor Deposition without Catalysts or Additives
Authors: Wang Lisheng , Zhang Xiaozhong , Zhao Songqing , Zhou Guoyuan , Zhou Yueliang , Qi Junjie 
Published: June 2019

AbstractWell-aligned ZnO nanowires were synthesized by simple physical vapor deposition using c-oriented ZnO thin films as substrate without catalysts or additives. The synthesized ZnO nanowires have two typical average diameters: 60 nm in majority and 120 nm in minority. They are about 4ím in length and well aligned along the normal direction of the substrate. Most of the synthesized ZnO nanowires are single crystalline in a hexagonal structure and grow along the [001] direction. The c-oriented ZnO thin films control the growth direction. Photoluminescence spectrum was measured showing a single strong ultraviolet emission (380 nm). Such result indicates that the ZnO nanowire arrays can be applied to excellent optoelectronic devices.
Shadow Nanosphere Lithography: Simulation and Experiment
Authors: Giersig Michael 
Published: June 2019

AbstractThe creation of two dimensional large-areas of nanoparticles of different morphology and ordering is still a not fully solved problem. The presented paper shows new outstanding methods based on nanosphere lithography for controlling the mask morphology to improve fabrication of nanoscales perfectly ordered over some cm2 dots, rods and rings. An annealed mask with 30nm aperatures was used for the fabrication of ferromagnetic iron nanorings. These nanosystems are expected to find various unique applications. Our method permitted fabrication of nanostructured materials with unique morphology and properties. This field is expected to open new venues in science and technology.
Mechanical Properties of Amorphous Al85Ni10La5 Alloy by Indentations
Authors: Zhang Zhihui , Ajdelsztajn Leonardo , Zhou Yizhang , Lavernia Enrique J. 
Published: June 2019

AbstractIndentation techniques have been carried out to study the mechanical behavior of amorphous Al85Ni10La5 alloy powders produced by inert gas atomization. The present work reveals that this amorphous alloy undergoes a three-stage crystallization process in the temperature range of 250°C ~ 390°C, with a glass transition temperature of approximately 259°C. In this study, the influence of devitrification on mechanical response was investigated via indentation of the Al85Ni10La5 alloy powders annealed at various temperatures, for instance, at temperatures well below or close to glass transition (235°C, 245°C, 250°C), and well above glass transition (283°C). Moreover, the microstructure evolution and the formation of nanoscale crystallites were studied using TEM and XRD. The influence of devitrification on the indentation response was characterized, paying particular attention to shear band formation and variations in hardness. The hardening behavior was analyzed on the basis of a rule-of-mixtures approach by treating the partially crystallized alloy as a nanocomposite.
Thermal Plasma Chemical Vapor Deposition of Superhard Nanostructured Si-C-N Coatings
Authors: Wagner Nicole J. , Cordill Megan J. , Zajickova Lenka , Gerberich William W. , Heberlein Joachim V. R. 
Published: June 2019

AbstractA triple torch plasma reactor was used to synthesize Si—C—N composite films via the thermal plasma chemical vapor deposition process. The argon-nitrogen plasma provided atomic nitrogen to carbon- and silicon-based reactants, which were injected through a central injection probe and ring configuration. Films were deposited with variations of the total nitrogen flow through the torches (1.5-4.5slm), reactant mixture (silicon tetrachloride and acetylene or hexamethyldisilazane) and substrate material (silicon and molybdenum). Micro X-ray diffraction was used to determine that both α-Si3N4 and β-Si3N4 were dominant in most of the depositions. Composites of silicon nitride and silicon carbide were synthesized on molybdenum. The bonding of amorphous phases was investigated using Fourier transform infrared spectroscopy, which indicated the presence of N—H, CHx and CΞ in various films. Indentation tests on the polished film cross-sections determined that large variations in hardness and elastic modulus existed for minor changes in film composition. Correlations between indentation results and scanning electron and optical microscope images showed that the mechanical properties greatly depend on the film morphology; the denser, smoother, and more crystalline films tended to display enhanced mechanical properties.
Investigation of the deformation behavior in nanoindented metal/nitride multilayers by coupling FIB-TEM and AFM observations
Authors: Abadias G. , Tromas C. , Tse Y.Y. , Michel A. 
Published: June 2019

AbstractEpitaxial TiN/Cu bilayers and multilayers with periods L between 5 and 50 nm have been grown by ultrahigh vacuum ion beam sputtering on Si and MgO(001) substrates at room temperature. The deformation modes induced by a Berkovich nanoindent have been imaged using Focused Ion Beam – Transmission Electron Microscopy (FIB-TEM) and Atomic Force Microscopy (AFM). The observations suggest that the mechanical response of the multilayers is essentially governed by an extensive plastic flow inside the Cu layers, which is confined by a bending of the more rigid TiN layers. This specific deformation behavior, with no contribution of the interfaces as a barrier for dislocation motion could explain the absence of significant hardness enhancement in this system.
Optimum Integrated Heterodyne Photoreceiver for Coherent Lidar Applications
Authors: Amzajerdian Farzin , Pierrottet Diego , Singh Upendra , Kavaya Michael 
Published: June 2019

AbstractMany coherent lidar applications, particularly airborne and space-based applications, impose stringent power and size constraints while requiring high levels of sensitivity. For this reason, optimization of the lidar heterodyne photoreceiver is one of the critical steps in ensuring full utilization of limited resources to achieve the required sensitivity. The analysis of 2-micron heterodyne receivers shows that substantial improvement of the order of 3 dB can be obtained by proper optimization of the receiver key control parameters and elimination of its parasitic capacitances by integrating the detector, its bias circuit, and the preamplifier on a single substrate. This paper describes analytical steps for defining optimum heterodyne receiver design parameters and development of experimental devices operating at 2-micron wavelength.
Measurement of Stress-strain Curves of PECVD Silicon Oxide Thin Films by Means of Nanoindentation
Authors: Cao Zhiqiang , Zhang Xin 
Published: June 2019

AbstractIn this paper, we explore the use of nanoindentation techniques as a method of measuring equivalent stress-strain curves of the PECVD SiOx thin films. Three indenter tips with different geometries were adopted in our experiments, enabling us to probe different regimes of plastic deformation in the PECVD SiOx thin films. A shear transformation zone (STZ) based amorphous plasticity theory is applied to depict the underlying plastic deformation mechanism.
Wear Resistance and Mechanical Properties of Polymeric Fibers Filled with Inorganic Fillers
Authors: Irisawa Toshihira , Shioya Masatoshi , Kobayashi Haruki , Kaneko Junichi 
Published: June 2019

AbstractThe wear resistance and the mechanical properties of polymer matrix composite fibers filled with inorganic fillers have been investigated in order to find out the way to increase the wear resistance of the fibers without losing tensile modulus and strength. Nylon 6 and poly(ethylene terephthalate) have been used as the matrix polymer and aluminum borate whisker and carbon nanotube have been used as the fillers. The wear resistance of the fibers has been evaluated by observing the fiber cross section after the side of the fiber was worn using a rotating drum covered with abrasive paper. The wear resistance of the nylon 6 and PET fibers was increased by the addition of these fillers without the loss of tensile modulus and strength. The effects of the addition of the fillers on the wear resistance have been compared with the effects of stretching and heat treatment of the fibers.
Helically Perforated Thin Films -- Dependence of Mechanical Properties on Microstructure
Authors: Fernando Sumudu P. , Elias Anastasia L. , Brett Michael J. 
Published: June 2019

AbstractThe effects of several microstructural parameters on the mechanical behaviour of a helically perforated thin film structure, or inverse microspring, were investigated using a finite element model[1]. The parameters investigated were the helical pitch angle, the cross-section radius, and the coil spacing. The elastic modulus was found to depend most strongly on the helical pitch angle (changing by a factor of 1.3 as the pitch angle went from 35° to 70°). Variations in the coil radius and the film thickness had a minor effect on the modulus. It was also found that using a finite size model (as opposed to an infinite model using periodic boundary conditions) produced better conditioned results. A preliminary confirmation of the model's validity was performed by comparison to nanoindentation results of a nickel helically perforated thin film.
Multipolar Expansion Methods for Coarse Grained Force Fields [PowerPoint Submission]
Authors: Chao Sheng D. 
Published: June 2019

AbstractCurrent large scale atomistic simulations remain too computationally demanding to be generally applicable to industrial and bioengineering materials. It is desirable to develop multiscale modeling algorithms to perform efficient and informative mesoscopic simulations. Here we present a multipolar expansion method to construct coarse grained force fields (CGFF) for polymer nanostructures and nanocomposites. This model can effectively capture the stereochemical response to anisotropic long-range interactions and can be systematically improved upon adding higher order terms. The coarse-graining procedure forms the basis to perform a hierarchy of multiscale simulations starting with the quantum chemistry calculations to coarse grained molecular dynamics, hopefully toward continuum modeling. We have applied this procedure to molecular clusters such as alkane, benzene, and fullerene. For liquid alkane, molecular dynamics simulations using the CGFF can reproduce the pair distribution functions using atomistic force fields. Molecular mechanics simulations using the CGFF can well reproduce the energetics of benzene clusters from quantum chemistry electronic structure calculations. Subtle anisotropy in the interaction potentials of the fullerene dimer using the Brenner force field can also be well represented by the model. It is promising this procedure can be standardized and further extended.
Effect of Surface Roughness on Remelting and Stresses During Splat Solidification [PowerPoint Submission]
Authors: Ye Guosheng , Khare Rajesh , Wroblewski Donald , Gevelber Michael , Basu Soumendra 
Published: June 2019

AbstractIn order to understand the microstructural evolution in plasma sprayed coatings, the solidification process was modeled using a 2-D FEM model based on enthalpy formation. Studies of the surface of the coatings showed surface roughnesses across multiple length scales. The model was used to examine the effects of the substrate and splat temperatures and the surface roughness features on the onset of remelting of the underlying surface on which the splat solidifies. The surface roughness was found to promote remelting, indicating that it was an important parameter that determines splat solidification. The temperatures of the splat and substrate were consolidated into one non-dimensional parameter that captured the onset of remelting with a non-dimensional remelting point.A fully coupled thermo-mechanical finite element model was also run for a single splat case, to provide more insight stress buildup during solidification. An important result was that the relative size of the surface roughness features, as compared to the splat thickness, is very important. Very large wavelengths compared to splat thickness lead to smaller stresses, since the solidification and the interface are essentially 1-D. Very small wavelengths compared to splat thickness also leads to reduced stresses, since the solidification front quickly becomes 1-D. Only roughness features on the scale of splat thickness are important in providing locations of maximum stress concentration, which are locations of microcrack formation.
Modeling of Atomistic Processes in Semiconductors: from Defect Signatures to a Hierarchy of Annealing Mechanisms
Authors: Bockstedte Michel 
Published: June 2019

AbstractThe modeling of atomistic processes in semiconductors based on the density functional theory is outlined. The role of intrinsic defects in the self and dopant diffusion, as well as in the dopant activation is investigated for the case of silicon carbide. A hierarchy of annealing mechanisms for vacancies and interstitials is proposed. The identification of the microscopic origin of experimental defect centers by calculated defect signatures establishes a link between theoretical modeling and experiments.
Computation of Temperature-Pressure Phase Diagrams of High-Pressure Nitrides
Authors: Kroll Peter 
Published: June 2019

AbstractWe propose an explicit scheme to include the fugacity of nitrogen in computations of phase diagrams of nitride compounds at high-temperature/high-pressure conditions. The assessment is based on available thermochemical data and two kind of extrapolating functions to provide upper and lower boundary for the fugacity coefficient as a funtion of p and T. The procedure is applied to investigate the synthesis of novel nitrides of tantalum, tungsten, and platinum. The combination of first-principle and thermochemical calculations let us predict the synthesis of a new high-pressure phase of Ta3N5 at about 27 GPa. Synthesis of WN2 becomes feasible at about 45 GPa. We furthermore explain why the synthesis of the noble metal subnitride, PtN2, occurs at about 40 GPa, and why PtN is not accessible in high-pressure experiments.
Does Osmium Carbide Exist? Ab initio Investigation
Authors: Zemzemi M. , Hebbache M. , Zivkovic D. , Stuparevic L 
Published: June 2019

AbstractTransition metals of the platinum group (Os, Ir, Pt, Ru, Re, Rh) do not form carbides and nitrides at ambient pressure. Osmium carbide seems to have been synthesized at zero pressure by Kempter and Nadler forty six years ago. According to the authors, OsC crystallizes in WC-type structure and has a hardness equal to 2000 kg mm-2. Up to date, no other experimental confirmation is available. We studied the electronic and mechanical properties of this hypothetical carbide using an approach based on the density-functional theory. We found that the work of the above mentioned authors is sound. The calculated lattice parameters are in good agreement with that given by those authors and a rough estimate also showed that the hardness given by them is reasonable. However, we found that the hexagonal structure of osmium carbide is electronically and mechanically unstable.
High-Pressure Studies of the Rotor-Stator Compound C60-Cubane
Authors: Sundqvist Bertil , Iwasiewicz-Wabnig Agnieszka , Kovats Eva , Pekker Sandor 
Published: June 2019

AbstractInsertion of cubane (C8H8) into the octahedral voids of the C60 lattice leads to the formation of an interesting rotor-stator compound which can be converted into a C60 co-polymer by heating. We have treated a number of C60·C8H8 samples for up to 3 h each in the range 380-875 K under pressures up to 2 GPa. The resulting materials were investigated by Raman spectroscopy and X-ray diffraction. Depending on treatment conditions, at least five different structural phases can be found. In addition to the four structural phases observed at atmospheric pressure and different temperatures we find that a new polymeric state is created at pressures above 1 GPa, and we tentatively identify its structure as pseudo-orthorhombic. The cubic-orthorhombic phase transition line is found to have a slope of 295 K GPa-1, much larger than the slope of the fcc-sc line in pure C60.
Some characterizations of inner product spaces based on angle
Authors: NABAVİ SALES S.m.s. 
Published: June 2019

A problem in functional analysis that arises naturally is about finding necessary and sufficient conditions for a normed space to be an inner product space. By answering this question, mathematicians try to understand the inner product and normed spaces features. In this note, we have discussed this issue and we prove some results concerned with it. We introduce a notion of angle between two vectors in a normed space, denoted by $A_\theta(.,.)$ where $\theta\neq{k\pi\over2}$. We also speak about a notion of orthogonality concerning it, we call it $\theta$-orthogonality.
Ruptura de la latencia física y germinación de semillas de Chiranthodendron pentadactylon (Malvaceae)
Authors: Apodaca-Martínez Maribel , Cetina Alcalá Victor Manuel , Jasso-Mata Jesús , López-López Miguel Ángel , González-Rosas Héctor , Uscanga-Mortera Ebandro , García-Esteva Antonio 
Published: June 2019

Antecedentes: Los problemas para propagar C. pentadactylon por semilla se deben a su poca disponibilidad, bajo porcentaje de germinación, plagas y periodo juvenil mayor a 25 años.Hipótesis: Existe variación morfofisiológica de la semilla entre árboles y los tratamientos pregerminativos incrementan el porcentaje y la velocidad de germinación en semillas con seis meses de almacenamiento a temperatura ambiente . Especie en estudio: Chiranthodendron pentadactylon Larreat.Sitio de estudio y fechas: Colegio de Postgraduados, Campus Montecillo, Estado de México, Méx. Junio, 2016.Métodos: Se determinó el contenido de humedad, la viabilidad y el efecto de tratamientos pregerminativos en el porcentaje y velocidad de germinación de las semillas . Se utilizó un diseño de bloques al azar. Los bloques al azar con los tratamientos: 1 (escarificación mecánica + estratificación en frío a 5 °C durante 5 días), 2 (escarificación mecánica + imbibición durante 12 h), 3 (escarificación mecánica + corte en la base de la semilla) y 4 (testigo). Los tratamientos se aleatorizaron dentro de cada bloque.Resultados: El contenido de humedad fue menor a 10 % y la viabilidad de 100 %. Se encontraron diferencias significativas en la germinación entre tratamientos. La prueba de Tukey (? = 0.05) mostró diferencias entre los tratamientos pregerminativos 1, 2 y 3 con respecto al T4. La velocidad de germinación registró el mayor valor en el tratamiento 3.Conclusiones: Con los tratamientos 1, 2 o 3 se obtuvo más de 77 % germinación. El tratamiento 3 mostró mayor velocidad de germinación, lo que resulta importante en la producción de plántulas.
Projecting the external health costs of a coal-fired power plant: The case of Kusile
Authors: Riekert Johannes W. , Koch Steven F. 
Published: June 2019

We examine an important subset of the expected health costs associated with the commissioning of Kusile, a new coal-fired electricity generation plant in South Africa. The subset of health impacts focuses on sulphur dioxides, nitrous oxides and large particulate matter (greater than 10 mm). The analysis makes use of the Impact Pathway Approach combined with the data transfer methodology. The plant, which is expected to contribute 4 800 MW of additional electricity to the South African grid is found to have modest health impacts, partly due to the limited additional pollutant emissions expected at the plant. Specifically, additional localised external health costs are found to be in the region of 0.09c/kWh to 6.08c/kWh. Limitations of the analysis are also examined.