Crystallization behavior of nanocomposites based on poly(L-lactide) and layered double hydroxides - Unbiased determination of the rigid amorphous phases due to the crystals and the nanofiller

Science.gov (United States)

Schoenhals, Andreas; Leng, Jing; Wurm, Andreas; Schick, Christoph

Semicrystalline polymers have to be described by a three phase model consisting of a mobile amorphous (MAF), a crystalline (CF), and a rigid amorphous fraction (RAF). For nanocomposites based on a semicrystalline polymer the RAF is due to both the crystallites (RAFcrystal) and the filler (RAFfiller) . In most cases a separation of both contributions is not possible without further assumptions. Here polymer nanocomposite based on poly(L-lactide) and layered double hydroxide nanofiller were prepared. Due to the low crystallization rate of PLA its crystallization can be suppressed by a high enough cooling rate, and the RAF is due only to the nanofiller. The MAF, CF, and RAF were estimated by Temperature Modulated DSC. For the first time CF, MAF, RAFcrystal, and RAFfiller could be estimated without any assumption. Two different systems with a different degree of exfoliation were prepared and discussed in detail.

Amorphous/crystal and polymer/filler interphases in biocomposites from poly(butylene succinate)

Energy Technology Data Exchange (ETDEWEB)

Signori, Francesca [Consiglio Nazionale delle Ricerche - Istituto per i Processi Chimico-Fisici (CNR-IPCF), Via G. Moruzzi 1, I-56124 Pisa (Italy); Pelagaggi, Martina [Universita di Pisa - Dipartimento di Chimica e Chimica Industriale, Via Risorgimento 35, I-56126 Pisa (Italy); Bronco, Simona [Consiglio Nazionale delle Ricerche - Istituto per i Processi Chimico-Fisici (CNR-IPCF), Via G. Moruzzi 1, I-56124 Pisa (Italy); Righetti, Maria Cristina, E-mail: righetti@ipcf.cnr.it [Consiglio Nazionale delle Ricerche - Istituto per i Processi Chimico-Fisici (CNR-IPCF), Via G. Moruzzi 1, I-56124 Pisa (Italy)

2012-09-10

Highlights: Black-Right-Pointing-Pointer The existence of intermolecular interactions between poly(butylene succinate) and hemp fibres was proved from specific heat capacities data. Black-Right-Pointing-Pointer Different degrees of mobility of the poly(butylene succinate) amorphous segments were evidenced at the amorphous/crystal interphase. Black-Right-Pointing-Pointer Devitrification of the rigid amorphous fraction in poly(butylene succinate) was found to occur before and simultaneously with the fusion. - Abstract: Poly(butylene succinate)-hemp composites (PBS-hemp), with hemp content in the range 0-40 wt.%, were prepared in the melt and characterized. This paper focuses on the detailed analysis of the thermal behaviour of the PBS-hemp composites, investigated by differential scanning calorimetry (DSC), to enlighten the polymer/fibre interphase features. The occurrence of specific intermolecular interactions between PBS and hemp was assessed from specific heat capacity data. Different degrees of mobility of the PBS amorphous segments were found at the amorphous/crystal interphases. A broadening of the bulk glass transition was observed, and attributed to the presence of polymer segments slightly constrained. Moreover, a rigid amorphous fraction that devitrifies at temperatures higher than the bulk glass transition, partly before the melting region and partly simultaneously with the fusion, was observed and quantified, and attributed to the presence of major constraints probably occurring in geometrically restricted areas.

Template-based CTA to x-ray angio rigid registration of coronary arteries in frequency domain with automatic x-ray segmentation

Energy Technology Data Exchange (ETDEWEB)

Aksoy, Timur; Unal, Gozde [Sabanci University, Tuzla, Istanbul 34956 (Turkey); Demirci, Stefanie; Navab, Nassir [Computer Aided Medical Procedures (CAMP), Technical University of Munich, Garching, 85748 (Germany); Degertekin, Muzaffer [Yeditepe University Hospital, Istanbul 34752 (Turkey)

2013-10-15

Purpose: A key challenge for image guided coronary interventions is accurate and absolutely robust image registration bringing together preinterventional information extracted from a three-dimensional (3D) patient scan and live interventional image information. In this paper, the authors present a novel scheme for 3D to two-dimensional (2D) rigid registration of coronary arteries extracted from preoperative image scan (3D) and a single segmented intraoperative x-ray angio frame in frequency and spatial domains for real-time angiography interventions by C-arm fluoroscopy.Methods: Most existing rigid registration approaches require a close initialization due to the abundance of local minima and high complexity of search algorithms. The authors' method eliminates this requirement by transforming the projections into translation-invariant Fourier domain for estimating the 3D pose. For 3D rotation recovery, template Digitally Reconstructed Radiographs (DRR) as candidate poses of 3D vessels of segmented computed tomography angiography are produced by rotating the camera (image intensifier) around the DICOM angle values with a specific range as in C-arm setup. The authors have compared the 3D poses of template DRRs with the segmented x-ray after equalizing the scales in three domains, namely, Fourier magnitude, Fourier phase, and Fourier polar. The best rotation pose candidate was chosen by one of the highest similarity measures returned by the methods in these domains. It has been noted in literature that frequency domain methods are robust against noise and occlusion which was also validated by the authors' results. 3D translation of the volume was then recovered by distance-map based BFGS optimization well suited to convex structure of the authors' objective function without local minima due to distance maps. A novel automatic x-ray vessel segmentation was also performed in this study.Results: Final results were evaluated in 2D projection space for

Template-based CTA to x-ray angio rigid registration of coronary arteries in frequency domain with automatic x-ray segmentation

International Nuclear Information System (INIS)

Aksoy, Timur; Unal, Gozde; Demirci, Stefanie; Navab, Nassir; Degertekin, Muzaffer

2013-01-01

Purpose: A key challenge for image guided coronary interventions is accurate and absolutely robust image registration bringing together preinterventional information extracted from a three-dimensional (3D) patient scan and live interventional image information. In this paper, the authors present a novel scheme for 3D to two-dimensional (2D) rigid registration of coronary arteries extracted from preoperative image scan (3D) and a single segmented intraoperative x-ray angio frame in frequency and spatial domains for real-time angiography interventions by C-arm fluoroscopy.Methods: Most existing rigid registration approaches require a close initialization due to the abundance of local minima and high complexity of search algorithms. The authors' method eliminates this requirement by transforming the projections into translation-invariant Fourier domain for estimating the 3D pose. For 3D rotation recovery, template Digitally Reconstructed Radiographs (DRR) as candidate poses of 3D vessels of segmented computed tomography angiography are produced by rotating the camera (image intensifier) around the DICOM angle values with a specific range as in C-arm setup. The authors have compared the 3D poses of template DRRs with the segmented x-ray after equalizing the scales in three domains, namely, Fourier magnitude, Fourier phase, and Fourier polar. The best rotation pose candidate was chosen by one of the highest similarity measures returned by the methods in these domains. It has been noted in literature that frequency domain methods are robust against noise and occlusion which was also validated by the authors' results. 3D translation of the volume was then recovered by distance-map based BFGS optimization well suited to convex structure of the authors' objective function without local minima due to distance maps. A novel automatic x-ray vessel segmentation was also performed in this study.Results: Final results were evaluated in 2D projection space for patient data; and

Fiscal 2000 survey report. Basic research on hot molding of amorphous ceramics; 2000 nendo amorphous netsukan ceramics seikeiho ni kansuru kiso kenkyu chosa hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Experiments were conducted on the plasticity processing of heat resistant ceramics making use of the viscous deformation of amorphous ceramics in the supercooled liquid temperature domain. Concerning the preparation of powder of amorphous ceramics, the plasma rotating electrode method of Institute for Materials Research, Tohoku University, was employed, and a bamboo leaf shaped amorphous flake was successfully fabricated by increasing the arc discharge current. In a search of texture easy to turn amorphous, it was observed that Al{sub 2}O{sub 3}-La{sub 2}O{sub 3} had a supercooled liquid domain of as large as 70K, and this enabled a conclusion that it was a promising candidate for hot molding in a supercooled liquid domain. In an experiment of molding in a supercooled liquid domain, Al{sub 2}O{sub 3}-Gd{sub 2}O{sub 3} was used in a press molding process. As the result, a compact bulk mold was obtained in a temperature domain far lower than in the case of conventional sintering. Crystallization had already advanced in all the molds experimentally fabricated by press molding, and this disabled a study of characteristics to be exhibited by an amorphous mold, but it was found that they had a compressive strength of approximately 1,800MPa. (NEDO)

Features of a time domain simulation tool for rigid riser design

Energy Technology Data Exchange (ETDEWEB)

Morooka, Celso K.; Brandt, Dustin M. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia de Petroleo; Matt, Cyntia G.C.; Franciss, Ricardo [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

2008-07-01

This paper present a number of numerical implementations designed for the analysis of rigid riser's static and dynamic behavior that includes the effects of vortex induced vibrations (VIV) and marine hydrodynamic loads in time domain. Features include the ability to consider pipe with a free-span utilizing a soil/riser interaction model. An implementation of a numerical coupling scheme to couple the vertical riser and platform dynamics was developed to allow prediction of the sub sea Blow-Out Preventer (BOP) re-entry into a sub sea petroleum well when drilling different phases of deep and ultra-deep wells. The developments contains support for the consideration of the Self Standing Hybrid Riser (SSHR) configuration which has been shown to be a promising riser configuration in deep and ultra-deep waters. A graphical interface was also created to better grasp the results and aid in the modeling, processing and to help analyze the numerical simulations, contributing to enhance agility and quality of the riser design and analysis processes. (author)

Terahertz time domain spectroscopy of amorphous and crystalline aluminum oxide nanostructures synthesized by thermal decomposition of AACH

Energy Technology Data Exchange (ETDEWEB)

Mehboob, Shoaib, E-mail: smehboob@pieas.edu.pk [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan); Mehmood, Mazhar [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan); Ahmed, Mushtaq [National Institute of Lasers and Optronics (NILOP), Nilore 45650, Islamabad (Pakistan); Ahmad, Jamil; Tanvir, Muhammad Tauseef [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan); Ahmad, Izhar [National Institute of Lasers and Optronics (NILOP), Nilore 45650, Islamabad (Pakistan); Hassan, Syed Mujtaba ul [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan)

2017-04-15

The objective of this work is to study the changes in optical and dielectric properties with the transformation of aluminum ammonium carbonate hydroxide (AACH) to α-alumina, using terahertz time domain spectroscopy (THz-TDS). The nanostructured AACH was synthesized by hydrothermal treatment of the raw chemicals at 140 °C for 12 h. This AACH was then calcined at different temperatures. The AACH was decomposed to amorphous phase at 400 °C and transformed to δ* + α-alumina at 1000 °C. Finally, the crystalline α-alumina was achieved at 1200 °C. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were employed to identify the phases formed after calcination. The morphology of samples was studied using scanning electron microscopy (SEM), which revealed that the AACH sample had rod-like morphology which was retained in the calcined samples. THz-TDS measurements showed that AACH had lowest refractive index in the frequency range of measurements. The refractive index at 0.1 THZ increased from 2.41 for AACH to 2.58 for the amorphous phase and to 2.87 for the crystalline α-alumina. The real part of complex permittivity increased with the calcination temperature. Further, the absorption coefficient was highest for AACH, which reduced with calcination temperature. The amorphous phase had higher absorption coefficient than the crystalline alumina. - Highlights: • Aluminum oxide nanostructures were obtained by thermal decomposition of AACH. • Crystalline phases of aluminum oxide have higher refractive index than that of amorphous phase. • The removal of heavier ionic species led to the lower absorption of THz radiations.

Melting and Pressure-Induced Amorphization of Quartz

OpenAIRE

Badro, James; Gillet, Philippe; Barrat, Jean-Louis

1997-01-01

It has recently been shown that amorphization and melting of ice were intimately linked. In this letter, we infer from molecular dynamics simulations on the SiO2 system that the extension of the quartz melting line in the metastable pressure-temperature domain is the pressure-induced amorphization line. It seems therefore likely that melting is the physical phenomenon responsible for pressure induced amorphization. Moreover, we show that the structure of a "pressure glass" is similar to that ...

Rigidity of Glasses and Macromolecules

Science.gov (United States)

Thorpe, M. F.

1998-03-01

The simple yet powerful ideas of percolation theory have found their way into many different areas of research. In this talk we show how RIGIDITY PERCOLATION can be studied at a similar level of sophistication, using a powerful new program THE PEBBLE GAME (D. J. Jacobs and M. F. Thorpe, Phys. Rev. E) 53, 3682 (1996). that uses an integer algorithm. This program can analyse the rigidity of two and three dimensional networks containing more than one million bars and joints. We find the total number of floppy modes, and find the critical behavior as the network goes from floppy to rigid as more bars are added. We discuss the relevance of this work to network glasses, and how it relates to experiments that involve the mechanical properties like hardness and elasticity of covalent glassy networks like Ge_xAs_ySe_1-x-y and dicuss recent experiments that suggest that the rigidity transition may be first order (Xingwei Feng, W. J.Bresser and P. Boolchand, Phys. Rev. Lett 78), 4422 (1997).. This approach is also useful in macromolecules and proteins, where detailed information about the rigid domain structure can be obtained.

Understanding geological processes: Visualization of rigid and non-rigid transformations

Science.gov (United States)

Shipley, T. F.; Atit, K.; Manduca, C. A.; Ormand, C. J.; Resnick, I.; Tikoff, B.

2012-12-01

Visualizations are used in the geological sciences to support reasoning about structures and events. Research in cognitive sciences offers insights into the range of skills of different users, and ultimately how visualizations might support different users. To understand the range of skills needed to reason about earth processes we have developed a program of research that is grounded in the geosciences' careful description of the spatial and spatiotemporal patterns associated with earth processes. In particular, we are pursuing a research program that identifies specific spatial skills and investigates whether and how they are related to each other. For this study, we focus on a specific question: Is there an important distinction in the geosciences between rigid and non-rigid deformation? To study a general spatial thinking skill we employed displays with non-geological objects that had been altered by rigid change (rotation), and two types of non-rigid change ("brittle" (or discontinuous) and "ductile" (or continuous) deformation). Disciplinary scientists (geosciences and chemistry faculty), and novices (non-science faculty and undergraduate psychology students) answered questions that required them to visualize the appearance of the object before the change. In one study, geologists and chemists were found to be superior to non-science faculty in reasoning about rigid rotations (e.g., what an object would look like from a different perspective). Geologists were superior to chemists in reasoning about brittle deformations (e.g., what an object looked like before it was broken - here the object was a word cut into many fragments displaced in different directions). This finding is consistent with two hypotheses: 1) Experts are good at visualizing the types of changes required for their domain; and 2) Visualization of rigid and non-rigid changes are not the same skill. An additional important finding is that there was a broad range of skill in both rigid and non-rigid

Designing heavy metal oxide glasses with threshold properties from network rigidity.

Science.gov (United States)

Chakraborty, Shibalik; Boolchand, P; Malki, M; Micoulaut, M

2014-01-07

Here, we show that a new class of glasses composed of heavy metal oxides involving transition metals (V2O5-TeO2) can surprisingly be designed from very basic tools using topology and rigidity of their underlying molecular networks. When investigated as a function of composition, such glasses display abrupt changes in network packing and enthalpy of relaxation at Tg, underscoring presence of flexible to rigid elastic phase transitions. We find that these elastic phases are fully consistent with polaronic nature of electronic conductivity at high V2O5 content. Such observations have new implications for designing electronic glasses which differ from the traditional amorphous electrolytes having only mobile ions as charge carriers.

Density of states in Mo-Ru amorphous alloys

International Nuclear Information System (INIS)

Miyakawa, W.

1985-01-01

The density of states is calculated for several compositions of amorphous Mo 1-x Ru x . In order to simulate amorphous clusters, the structures (atomic positions) utilized in the calculations were built from a small dense randomly packed unit of hard spheres with periodic boundary conditions. The density of states is calculated from a tight-binding Hamiltonian with hopping integrals parametrized in terms of the ddσ, ddΠ and ddδ molecular integrals. The results for pure Mo and pure Ru, compared in the canonical band aproximation, agree well with the literature. For binary alloys, the comparison of the calculated density of states with the rigid band aproximation results indicates that a more complex approach than the rigid band model must be used, even when the two atoms have similar bands, with band centers at nearly the same energy. The results also indicate that there is no relation between the peak in the superconducting critical temperature as a function of the number of valence eletrons per atom (e/a) in the region near Mo(e/a=6) and the peak of the density of states at the Fermi level in the same region, as has been sugested by some authors. (Author) [pt

Bringing nanomagnetism to the mesoscale with artificial amorphous structures

Science.gov (United States)

Muscas, G.; Brucas, R.; Jönsson, P. E.

2018-05-01

In the quest for materials with emergent or improved properties, an effective route is to create artificial superstructures. Novel properties emerge from the coupling between the phases, but the strength of this coupling depends on the quality of the interfaces. Atomic control of crystalline interfaces is notoriously complicated and to elude that obstacle, we suggest here an all-amorphous design. Starting from a model amorphous iron alloy, we locally tune the magnetic behavior by creating boron-doped regions by means of ion implantation through a lithographic mask. This process preserves the amorphous environment, creating a non-topographic magnetic superstructure with smooth interfaces and no structural discontinuities. The absence of inhomogeneities acting as pinning centers for the magnetization reversal is demonstrated by the formation of magnetic vortexes for ferromagnetic disks as large as 20 µm in diameter embedded within a paramagnetic matrix. Rigid exchange coupling between two amorphous ferromagnetic phases in a microstructured sample is evidenced by an investigation involving first-order reversal curves. The sample consists of a soft matrix with embedded elements constituting a hard phase where the anisotropy originates from an elongated shape of the elements. We provide an intuitive explanation for the micrometer-range exchange coupling mechanism and discuss how to tailor the properties of all-amorphous superstructures.

Analysis of an ideal amorphous solid

International Nuclear Information System (INIS)

To, L.T.; Stachurski, Z.H.

2004-01-01

Full text: In geometrical terms, amorphous solids are fundamentally different from crystalline solids in that they can not be constructed by the crystallographic method of translation of the basis along a lattice. Therefore, to study amorphous structures we must invoke concepts and use measures different to those used for ordered structures. Nevertheless, an ideal amorphous solid must share together with the ideal crystalline solid in the same definition of the term 'ideal'. In both cases it must be a perfect body, in which perfection is carried through in every detail to an unlimited (infinite) size without fault or defect. The latest results on this research will be presented. To qualify for a solid, rigid body, close packing of the spheres is required. For an ideal amorphous solids composed of hard spheres of identical size, we impose a stricter condition for the packing, namely, to be such that all spheres are in fixed positions (no loose spheres). To define the ideal solid, we must define what we mean by a perfect amorphous structure. Here, perfection is defined by, first the definition of imperfections, and next by the requirement of absence of imperfections of any kind. We envisage two types of defects: (i) geometrical, and (ii) statistical. Geometrical defects are: a sphere of different size, a loose sphere, and a vacancy. A statistical defect is defined with respect to two statistical functions: Ψ(N C ), and Φ(S β ). The former describes the probability of a given sphere having nc number of touching contacts, and the latter describes the disposition of the contacts on the surface of the sphere. Defects relating to the two functions will be described. The results for the functions, Ψ(N C ), and Φ(S β ), for the corresponding radial distribution function, and so called blocking number will be presented from simulations of an ideal amorphous solid

Amino propynyl benzoic acid building block in rigid spacers of divalent ligands binding to the Syk SH2 domains with equally high affinity as the natural ligand

NARCIS (Netherlands)

Dekker, Frank J; de Mol, Nico J; Fischer, Marcel J E; Liskamp, Rob M J; Dekker, Frank

2003-01-01

The construction of rigid spacers composed of amino propynyl benzoic acid building blocks is described. These spacers were used to link two phosphopeptide ligand sites towards obtaining divalent ligands with a high affinity for Syk tandem SH2 domains, which are important in signal transduction. The

Hydrolysis of the amorphous cellulose in cotton-based paper.

Science.gov (United States)

Stephens, Catherine H; Whitmore, Paul M; Morris, Hannah R; Bier, Mark E

2008-04-01

Hydrolysis of cellulose in Whatman no. 42 cotton-based paper was studied using gel permeation chromatography (GPC), electrospray ionization-mass spectrometry (ESI-MS), and uniaxial tensile testing to understand the course and kinetics of the reaction. GPC results suggested that scission reactions passed through three stages. Additionally, the evolution of soluble oligomers in the ESI-MS data and the steady course of strength loss showed that the hydrolysis reaction occurred at a constant rate. These findings are explained with a more detailed description of the cellulose hydrolysis, which includes multiple chain scissions on amorphous segments. The breaks occur with increasing frequency near the ends of amorphous segments, where chains protrude from crystalline domains. Oligomers unattached to crystalline domains are eventually created. Late-stage reactions near the ends of amorphous segments produce a kinetic behavior that falsely suggests that hydrolysis had ceased. Monte Carlo simulations of cellulose degradation corroborated the experimental findings.

A 3D, fully Eulerian, VOF-based solver to study the interaction between two fluids and moving rigid bodies using the fictitious domain method

Science.gov (United States)

Pathak, Ashish; Raessi, Mehdi

2016-04-01

We present a three-dimensional (3D) and fully Eulerian approach to capturing the interaction between two fluids and moving rigid structures by using the fictitious domain and volume-of-fluid (VOF) methods. The solid bodies can have arbitrarily complex geometry and can pierce the fluid-fluid interface, forming contact lines. The three-phase interfaces are resolved and reconstructed by using a VOF-based methodology. Then, a consistent scheme is employed for transporting mass and momentum, allowing for simulations of three-phase flows of large density ratios. The Eulerian approach significantly simplifies numerical resolution of the kinematics of rigid bodies of complex geometry and with six degrees of freedom. The fluid-structure interaction (FSI) is computed using the fictitious domain method. The methodology was developed in a message passing interface (MPI) parallel framework accelerated with graphics processing units (GPUs). The computationally intensive solution of the pressure Poisson equation is ported to GPUs, while the remaining calculations are performed on CPUs. The performance and accuracy of the methodology are assessed using an array of test cases, focusing individually on the flow solver and the FSI in surface-piercing configurations. Finally, an application of the proposed methodology in simulations of the ocean wave energy converters is presented.

Interface-mediated amorphization of coesite by 200 keV electron irradiation

International Nuclear Information System (INIS)

Gong, W.L.; Wang, L.M.; Ewing, R.C.; Xie, H.S.

1997-01-01

Electron-induced amorphization of coesite was studied as a function of irradiation temperature by in situ transmission electron microscopy at an incident energy of 200 keV. Electron-induced amorphization of coesite is induced by an ionization mechanism and is mainly dominated by an interface-mediated, heterogeneous nucleation-and-growth controlled process. Amorphous domains nucleate at surfaces, crystalline-amorphous (c-a) interfaces, and grain boundaries. This is the same process as the interface-mediated vitrification of coesite by isothermal annealing above the thermodynamic melting temperature (875 K), but below the glass transition temperature (1480 K). The interface-mediated amorphization of coesite by electron irradiation is morphologically similar to interface-mediated thermodynamic melting. copyright 1997 American Institute of Physics

Molecular simulation of freestanding amorphous nickel thin films

Energy Technology Data Exchange (ETDEWEB)

Dong, T.Q. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, UMR 8208 CNRS, 5 Boulevard Descartes, 77454 Marne-la-Vallée, Cedex 2 (France); Hoang, V.V., E-mail: vvhoang2002@yahoo.com [Department of Physics, Institute of Technology, National University of Ho Chi Minh City, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City (Viet Nam); Lauriat, G. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, UMR 8208 CNRS, 5 Boulevard Descartes, 77454 Marne-la-Vallée, Cedex 2 (France)

2013-10-31

Size effects on glass formation in freestanding Ni thin films have been studied via molecular dynamics simulation with the n-body Gupta interatomic potential. Atomic mechanism of glass formation in the films is determined via analysis of the spatio-temporal arrangements of solid-like atoms occurred upon cooling from the melt. Solid-like atoms are detected via the Lindemann ratio. We find that solid-like atoms initiate and grow mainly in the interior of the film and grow outward. Their number increases with decreasing temperature and at a glass transition temperature they dominate in the system to form a relatively rigid glassy state of a thin film shape. We find the existence of a mobile surface layer in both liquid and glassy states which can play an important role in various surface properties of amorphous Ni thin films. We find that glass formation is size independent for models containing 4000 to 108,000 atoms. Moreover, structure of amorphous Ni thin films has been studied in details via coordination number, Honeycutt–Andersen analysis, and density profile which reveal that amorphous thin films exhibit two different parts: interior and surface layer. The former exhibits almost the same structure like that found for the bulk while the latter behaves a more porous structure containing a large amount of undercoordinated sites which are the origin of various surface behaviors of the amorphous Ni or Ni-based thin films found in practice. - Highlights: • Glass formation is analyzed via spatio-temporal arrangements of solid-like atoms. • Amorphous Ni thin film exhibits two different parts: surface and interior. • Mobile surface layer enhances various surface properties of the amorphous Ni thin films. • Undercoordinated sites play an important role in various surface activities.

Optical response of thin amorphous films to infrared radiation

Science.gov (United States)

Orosco, J.; Coimbra, C. F. M.

2018-03-01

We briefly review the electrical-optical response of materials to radiative forcing within the formalism of the Kramers-Kronig relations. A commensurate set of criteria is described that must be met by any frequency-domain model representing the time-domain response of a real (i.e., physically possible) material. The criteria are applied to the Brendel-Bormann (BB) oscillator, a model that was originally introduced for its fidelity at reproducing the non-Lorentzian peak broadening experimentally observed in the infrared absorption by thin amorphous films but has since been used for many other common materials. We show that the BB model fails to satisfy the established physical criteria. Taking an alternative approach to the model derivation, a physically consistent model is proposed. This model provides the appropriate line-shape broadening for modeling the infrared optical response of thin amorphous films while adhering strictly to the Kramers-Kronig criteria. Experimental data for amorphous alumina (Al2O3 ) and amorphous quartz silica (SiO2) are used to obtain model parametrizations for both the noncausal BB model and the proposed causal model. The proposed model satisfies consistency criteria required by the underlying physics and reproduces the experimental data with better fidelity (and often with fewer parameters) than previously proposed permittivity models.

Amorphous surface layer versus transient amorphous precursor phase in bone - A case study investigated by solid-state NMR spectroscopy.

Science.gov (United States)

Von Euw, Stanislas; Ajili, Widad; Chan-Chang, Tsou-Hsi-Camille; Delices, Annette; Laurent, Guillaume; Babonneau, Florence; Nassif, Nadine; Azaïs, Thierry

2017-09-01

phosphate (ACP) environments could also arise from a transient amorphous precursor phase of apatite. Here, we provide an NMR spectroscopy methodology to reveal the origin of these ACP environments in bone mineral or in biomimetic apatite. The 1 H magnetization exchange between protons arising from amorphous and crystalline domains shows unambiguously that an ACP layer coats the apatitic crystalline core of bone et biomimetic apatite platelets. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Coercivities of hot-deformed magnets processed from amorphous and nanocrystalline precursors

International Nuclear Information System (INIS)

Tang, Xin; Sepehri-Amin, H.; Ohkubo, T.; Hioki, K.; Hattori, A.; Hono, K.

2017-01-01

Hot-deformed magnets have been processed from amorphous and nanocrystalline precursors and their hard magnetic properties and microstructures have been investigated in order to explore the optimum process route. The hot-deformed magnets processed from an amorphous precursor exhibited the coercivity of 1.40 T that is higher than that processed from nanocrystalline powder, ∼1.28 T. The average grain size was larger in the magnets processed from amorphous precursor. Detailed microstructure analyses by aberration corrected scanning transmission electron microscopy revealed that the Nd + Pr concentrations in the intergranular phases were higher in the hot-deformed magnet processed from the amorphous precursor, which is considered to lead to the enhanced coercivity due to a stronger pinning force against magnetic domain wall motion.

Kinetically Controlled Two-Step Amorphization and Amorphous-Amorphous Transition in Ice

Science.gov (United States)

Lin, Chuanlong; Yong, Xue; Tse, John S.; Smith, Jesse S.; Sinogeikin, Stanislav V.; Kenney-Benson, Curtis; Shen, Guoyin

2017-09-01

We report the results of in situ structural characterization of the amorphization of crystalline ice Ih under compression and the relaxation of high-density amorphous (HDA) ice under decompression at temperatures between 96 and 160 K by synchrotron x-ray diffraction. The results show that ice Ih transforms to an intermediate crystalline phase at 100 K prior to complete amorphization, which is supported by molecular dynamics calculations. The phase transition pathways show clear temperature dependence: direct amorphization without an intermediate phase is observed at 133 K, while at 145 K a direct Ih-to-IX transformation is observed; decompression of HDA shows a transition to low-density amorphous ice at 96 K and ˜1 Pa , to ice Ic at 135 K and to ice IX at 145 K. These observations show that the amorphization of compressed ice Ih and the recrystallization of decompressed HDA are strongly dependent on temperature and controlled by kinetic barriers. Pressure-induced amorphous ice is an intermediate state in the phase transition from the connected H-bond water network in low pressure ices to the independent and interpenetrating H-bond network of high-pressure ices.

Numerical procedure for fluid-structure interaction with structure displacements limited by a rigid obstacle

Directory of Open Access Journals (Sweden)

Yakhlef O.

2017-06-01

Full Text Available A fixed point algorithmis proposed to solve a fluid-structure interaction problem with the supplementary constraint that the structure displacements are limited by a rigid obstacle. Fictitious domain approach with penalization is used for the fluid equations. The surface forces from the fluid acting on the structure are computed using the fluid solution in the structure domain. The continuity of the fluid and structure velocities is imposed through the penalization parameter. The constraint of non-penetration of the elastic structure into the rigid obstacle is treated weakly. A convex constrained optimization problem is solved in order to get the structure displacements. Numerical results are presented.

MFM observations of domain wall creep and pinning effects in amorphous CoxSi1-x films with diluted arrays of antidots

International Nuclear Information System (INIS)

Rodriguez-Rodriguez, G; Perez-Junquera, A; Velez, M; Anguita, J V; Martin, J I; Rubio, H; Alameda, J M

2007-01-01

Magnetic force microscopy (MFM) has been used to analyse the behaviour of domain walls in uniaxial amorphous Co x Si 1-x films patterned with diluted arrays of antidots by electron beam lithography. The walls are found to be pinned by the antidot array when the antidot density is high enough along the easy axis. The expansion of reversed nuclei under the influence of the tip stray field has been observed in several consecutive MFM images of the same area, showing how the competition between line tension effects and pinning by the patterned holes governs the creep motion of the 180 0 walls across the array of antidots

Structure and properties of bulk amorphous magnetically soft coatings prepared by plasma spraying

International Nuclear Information System (INIS)

Kalita, V.I.; Kekalo, I.B.; Komlev, D.I.; Taranichev, V.E.

1995-01-01

Co-Ni-Fe-Si-B composition plasma coatings consisting of amorphous disk-shaped particles forming the bulk of a coating, of crystalline particles and of a threshold space, were studied. Iron and metalloid distribution heterogeneous by the thickness represents a peculiar feature for coating amorphous particles. Structure of coatings and their magnetic properties depend on some technological parameters. Conclusion is made that at annealing the variation of magnetic properties is determined by the processes of directed ordering and stratification of amorphous phase, while the low level of the initial magnetic properties of coatings is caused alongside with structure peculiarities, by occurrence of independent fine-dispersive domain structure in each disk-shaped amorphous phase. 14 refs., 8 figs., 6 tabs

Neutron depolarization study of internal stresses in amorphous Fe40Ni40B20

International Nuclear Information System (INIS)

de Jong, M.; Sietsma, J.; Rekveldt, M.T.; van den Beukel, A.

1997-01-01

The magnetic domain structure of amorphous ferromagnets with nonzero magnetostriction is mainly determined by the internal stress state because of the magneto-elastic coupling. The stress and field dependence of the domain structure contains important information on the internal stresses in the material. The three-dimensional neutron depolarization technique has been used to study the stress- and field-dependence of the bulk domain structures in both as-quenched and annealed ribbons of the metallic glass Fe 40 Ni 40 B 20 . A three-layer domain structure model corresponding to compressive and tensile internal stresses is presented to explain the measured data. The influence of surface roughness on the interpretation of neutron depolarization measurements in amorphous ribbons is discussed. Finally, the internal stress relaxation due to the annealing is explained in terms of the viscous behaviour of the glass. copyright 1997 American Institute of Physics

1H-detected MAS solid-state NMR experiments enable the simultaneous mapping of rigid and dynamic domains of membrane proteins

Science.gov (United States)

Gopinath, T.; Nelson, Sarah E. D.; Veglia, Gianluigi

2017-12-01

Magic angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy is emerging as a unique method for the atomic resolution structure determination of native membrane proteins in lipid bilayers. Although 13C-detected ssNMR experiments continue to play a major role, recent technological developments have made it possible to carry out 1H-detected experiments, boosting both sensitivity and resolution. Here, we describe a new set of 1H-detected hybrid pulse sequences that combine through-bond and through-space correlation elements into single experiments, enabling the simultaneous detection of rigid and dynamic domains of membrane proteins. As proof-of-principle, we applied these new pulse sequences to the membrane protein phospholamban (PLN) reconstituted in lipid bilayers under moderate MAS conditions. The cross-polarization (CP) based elements enabled the detection of the relatively immobile residues of PLN in the transmembrane domain using through-space correlations; whereas the most dynamic region, which is in equilibrium between folded and unfolded states, was mapped by through-bond INEPT-based elements. These new 1H-detected experiments will enable one to detect not only the most populated (ground) states of biomacromolecules, but also sparsely populated high-energy (excited) states for a complete characterization of protein free energy landscapes.

Novel trends in the study of magnetically soft Co-based amorphous glass-coated wires

International Nuclear Information System (INIS)

Chiriac, H.; Ovari, T.-A.

2011-01-01

An overview of the recent progress and state-of-the-art results in the investigation of the amorphous glass-coated wires with nearly zero magnetostriction is presented. These versatile microwires display enhanced soft magnetic properties, which make them suitable as sensing elements in various sensors for biomedical and automotive applications. Current results on their magnetic characteristics refer to a major refinement of their core-shell magnetic structure by taking into account the interdomain wall and to the thorough analysis of the magnetization within the outer shell. Experimental techniques such as giant magneto-impedance, magneto-resistance, and magneto-optical Kerr effect measurements are employed to prove the outcome of the theoretical calculations. The impact of the magnetic structure of the outer shell on the propagation of domain walls in bistable amorphous wires is analyzed. Very recent results on the magnetization process in nearly zero magnetostrictive amorphous glass-coated wires with submicron dimensions are also reviewed. - Highlights: → The most recent advances in the study of amorphous glass-coated wires with nearly zero magnetostriction are surveyed. → Major progress in the study of their domain structure: the wide interdomain wall, which affects high frequency phenomena. → The magnetization of the outer shell depends on wire diameter and affects the wall propagation in bistable samples. → These novel results are important for future sensor applications of nearly zero magnetostrictive amorphous microwires.

Effort Flow Analysis: A Methodology for Directed Product Evolution Using Rigid Body and Compliant Mechanisms

National Research Council Canada - National Science Library

Greer, James

2002-01-01

This dissertation presents a systematic design methodology for directed product evolution that uses both rigid body and compliant mechanisms to facilitate component combination in the domain of mechanical products...

The Stabilization of Amorphous Zopiclone in an Amorphous Solid Dispersion.

Science.gov (United States)

Milne, Marnus; Liebenberg, Wilna; Aucamp, Marique

2015-10-01

Zopiclone is a poorly soluble psychotherapeutic agent. The aim of this study was to prepare and characterize an amorphous form of zopiclone as well as the characterization and performance of a stable amorphous solid dispersion. The amorphous form was prepared by the well-known method of quench-cooling of the melt. The solid dispersion was prepared by a solvent evaporation method of zopiclone, polyvinylpyrrolidone-25 (PVP-25), and methanol, followed by freeze-drying. The physico-chemical properties and stability of amorphous zopiclone and the solid dispersion was studied using differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), hot-stage microscopy (HSM), X-ray diffractometry (XRD), solubility, and dissolution studies. The zopiclone amorphous solid-state form was determined to be a fragile glass; it was concluded that the stability of the amorphous form is influenced by both temperature and water. Exposure of amorphous zopiclone to moisture results in rapid transformation of the amorphous form to the crystalline dihydrated form. In comparison, the amorphous solid dispersion proved to be more stable with increased aqueous solubility.

Rigid multibody system dynamics with uncertain rigid bodies

Energy Technology Data Exchange (ETDEWEB)

Batou, A., E-mail: anas.batou@univ-paris-est.fr; Soize, C., E-mail: christian.soize@univ-paris-est.fr [Universite Paris-Est, Laboratoire Modelisation et Simulation Multi Echelle, MSME UMR 8208 CNRS (France)

2012-03-15

This paper is devoted to the construction of a probabilistic model of uncertain rigid bodies for multibody system dynamics. We first construct a stochastic model of an uncertain rigid body by replacing the mass, the center of mass, and the tensor of inertia by random variables. The prior probability distributions of the stochastic model are constructed using the maximum entropy principle under the constraints defined by the available information. The generators of independent realizations corresponding to the prior probability distribution of these random quantities are further developed. Then several uncertain rigid bodies can be linked to each other in order to calculate the random response of a multibody dynamical system. An application is proposed to illustrate the theoretical development.

Coupling between Current and Dynamic Magnetization : from Domain Walls to Spin Waves

Science.gov (United States)

Lucassen, M. E.

2012-05-01

So far, we have derived some general expressions for domain-wall motion and the spin motive force. We have seen that the β parameter plays a large role in both subjects. In all chapters of this thesis, there is an emphasis on the determination of this parameter. We also know how to incorporate thermal fluctuations for rigid domain walls, as shown above. In Chapter 2, we study a different kind of fluctuations: shot noise. This noise is caused by the fact that an electric current consists of electrons, and therefore has fluctuations. In the process, we also compute transmission and reflection coefficients for a rigid domain wall, and from them the linear momentum transfer. More work on fluctuations is done in Chapter 3. Here, we consider a (extrinsically pinned) rigid domain wall under the influence of thermal fluctuations that induces a current via spin motive force. We compute how the resulting noise in the current is related to the β parameter. In Chapter 4 we look into in more detail into the spin motive forces from field driven domain walls. Using micro magnetic simulations, we compute the spin motive force due to vortex domain walls explicitly. As mentioned before, this gives qualitatively different results than for a rigid domain wall. The final subject in Chapter 5 is the application of the general expression for spin motive forces to magnons. Although this might seem to be unrelated to domain-wall motion, this calculation allows us to relate the β parameter to macroscopic transport coefficients. This work was supported by Stichting voor Fundamenteel Onderzoek der Materie (FOM), the Netherlands Organization for Scientific Research (NWO), and by the European Research Council (ERC) under the Seventh Framework Program (FP7).

Thickness dependence of magnetic anisotropy and domains in amorphous Co{sub 40}Fe{sub 40}B{sub 20} thin films grown on PET flexible substrates

Energy Technology Data Exchange (ETDEWEB)

Tang, Zhenhua, E-mail: tangzhenhua1988@163.com [Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006 (China); Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Ni, Hao [Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China); College of science, China university of petroleum, Qingdao, Shandong 266580 China (China); Lu, Biao [Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006 (China); Zheng, Ming [Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Huang, Yong-An [Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006 (China); Lu, Sheng-Guo, E-mail: sglu@gdut.edu.cn [Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006 (China); Tang, Minghua [Key Laboratory of Low Dimensional Materials and Application Technology, Ministry of Education (Xiangtan University), Xiangtan, Hunan 411105 (China); Gao, Ju [Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China)

2017-03-15

The amorphous Co{sub 40}Fe{sub 40}B{sub 20} (CoFeB) films (5–200 nm in thickness) were grown on flexible polyethylene terephthalate (PET) substrates using the DC magnetron-sputtering method. The thickness dependence of structural and magnetic properties of flexible CoFeB thin films was investigated in detail. The in-plane uniaxial magnetic anisotropy induced by strain as a function of thickness was obtained in flexible CoFeB thin films, and a critical thickness of ~150 nm for in-plane magnetic anisotropy was observed. Moreover, the domains and the uniaxial anisotropy as a function of angular direction of applied magnetic field were characterized. The results show potential for designing CoFeB-based flexible spintronic devices in which the physical parameters could be tailored by controlling the thickness of the thin film. - Graphical abstract: The in-plane uniaxial magnetic anisotropy induced by strain as a function of thickness was obtained in flexible CoFeB thin films, and a critical thickness of ~150 nm for in-plane magnetic anisotropy was observed. Moreover, the domains and the uniaxial anisotropy as a function of angular direction of applied magnetic field were characterized. - Highlights: • The thickness effect on the magnetic properties in amorphous CoFeB thin films grown on flexible substrates was investigated. • The in-plane uniaxial magnetic anisotropy induced by strains was observed. • A critical thickness of ~ 150 nm for the flexible CoFeB thin film on PET substrate was obtained.

Amorphous metal composites

International Nuclear Information System (INIS)

Byrne, M.A.; Lupinski, J.H.

1984-01-01

This patent discloses an improved amorphous metal composite and process of making the composite. The amorphous metal composite comprises amorphous metal (e.g. iron) and a low molecular weight thermosetting polymer binder. The process comprises placing an amorphous metal in particulate form and a thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite

Magnetic structure of Fe-based amorphous and thermal annealed microwires

International Nuclear Information System (INIS)

Olivera, J.; Provencio, M.; Prida, V.M.; Hernando, B.; Santos, J.D.; Perez, M.J.; Gorria, P.; Sanchez, M.L.; Belzunce, F.J.

2005-01-01

The magnetic structure of amorphous and thermal annealed glass coated microwires is studied by thermomagnetic, DSC, and Bitter domain pattern techniques. The long-range dipolar interaction between parallel aligned microwires and the appearance of large Barkhausen jumps steps in the axially magnetized loops are discussed in terms of reversal magnetization process

High-density amorphous ice: nucleation of nanosized low-density amorphous ice

Science.gov (United States)

Tonauer, Christina M.; Seidl-Nigsch, Markus; Loerting, Thomas

2018-01-01

The pressure dependence of the crystallization temperature of different forms of expanded high-density amorphous ice (eHDA) was scrutinized. Crystallization at pressures 0.05-0.30 GPa was followed using volumetry and powder x-ray diffraction. eHDA samples were prepared via isothermal decompression of very high-density amorphous ice at 140 K to different end pressures between 0.07-0.30 GPa (eHDA0.07-0.3). At 0.05-0.17 GPa the crystallization line T x (p) of all eHDA variants is the same. At pressures  >0.17 GPa, all eHDA samples decompressed to pressures  <0.20 GPa exhibit significantly lower T x values than eHDA0.2 and eHDA0.3. We rationalize our findings with the presence of nanoscaled low-density amorphous ice (LDA) seeds that nucleate in eHDA when it is decompressed to pressures  <0.20 GPa at 140 K. Below ~0.17 GPa, these nanosized LDA domains are latent within the HDA matrix, exhibiting no effect on T x of eHDA<0.2. Upon heating at pressures  ⩾0.17 GPa, these nanosized LDA nuclei transform to ice IX nuclei. They are favored sites for crystallization and, hence, lower T x . By comparing crystallization experiments of bulk LDA with the ones involving nanosized LDA we are able to estimate the Laplace pressure and radius of ~0.3-0.8 nm for the nanodomains of LDA. The nucleation of LDA in eHDA revealed here is evidence for the first-order-like nature of the HDA  →  LDA transition, supporting water’s liquid-liquid transition scenarios.

The use of ionic salt dyes as amorphous, thermally stable emitting layers in organic light-emitting diodes

Science.gov (United States)

Chondroudis, Konstantinos; Mitzi, David B.

2000-01-01

The conversion of two neutral dye molecules (D) to ionic salts (H2N-D-NH2ṡ2HX) and their utilization as emitting layers in organic light-emitting diodes (OLEDs) is described. The dye salts, AEQTṡ2HCl and APTṡ2HCl, can be deposited as amorphous films using conventional evaporation techniques. X-ray diffraction and scanning electron microscopy analysis, coupled with thermal annealing studies, demonstrate the resistance of the films to crystallization. This stability is attributed to strong ionic forces between the relatively rigid molecules. OLEDs incorporating such salts for emitting layers exhibit better thermal stability compared with devices made from the corresponding neutral dyes (H2N-D-NH2). These results suggest that ionic salts may more generally enable the formation of thermally stable, amorphous emitting, and charge transporting layers.

Topological classification of the Goryachev integrable case in rigid body dynamics

International Nuclear Information System (INIS)

Nikolaenko, S S

2016-01-01

A topological analysis of the Goryachev integrable case in rigid body dynamics is made on the basis of the Fomenko-Zieschang theory. The invariants (marked molecules) which are obtained give a complete description, from the standpoint of Liouville classification, of the systems of Goryachev type on various level sets of the energy. It turns out that on appropriate energy levels the Goryachev case is Liouville equivalent to many classical integrable systems and, in particular, the Joukowski, Clebsch, Sokolov and Kovalevskaya-Yehia cases in rigid body dynamics, as well as to some integrable billiards in plane domains bounded by confocal quadrics -- in other words, the foliations given by the closures of generic solutions of these systems have the same structure. Bibliography: 15 titles

Radiation amorphization of materials

International Nuclear Information System (INIS)

Neklyudov, I.M.; Chernyaeva, T.P.

1993-01-01

The results of experimental and theoretical research on radiation amorphization are presented in this analytical review. Mechanism and driving forces of radiation amorphization are described, kinetic and thermodynamic conditions of amorphization are formulated. Compositional criteria of radiation amorphization are presented, that allow to predict irradiation behaviour of materials, their tendency to radiation amorphization. Mechanism of transition from crystalline state to amorphous state are considered depending on dose, temperature, structure of primary radiation damage and flux level. (author). 134 refs., 4 tab., 25 fig

Methods of amorphization and investigation of the amorphous state

OpenAIRE

EINFALT, TOMAŽ; PLANINŠEK, ODON; HROVAT, KLEMEN

2013-01-01

The amorphous form of pharmaceutical materials represents the most energetic solid state of a material. It provides advantages in terms of dissolution rate and bioavailability. This review presents the methods of solid-state amorphization described in literature (supercooling of liquids, milling, lyophilization, spray drying, dehydration of crystalline hydrates), with the emphasis on milling. Furthermore, we describe how amorphous state of pharmaceuticals differ depending on method of prepara...

Blind source separation based on time-frequency morphological characteristics for rigid acoustic scattering by underwater objects

Science.gov (United States)

Yang, Yang; Li, Xiukun

2016-06-01

Separation of the components of rigid acoustic scattering by underwater objects is essential in obtaining the structural characteristics of such objects. To overcome the problem of rigid structures appearing to have the same spectral structure in the time domain, time-frequency Blind Source Separation (BSS) can be used in combination with image morphology to separate the rigid scattering components of different objects. Based on a highlight model, the separation of the rigid scattering structure of objects with time-frequency distribution is deduced. Using a morphological filter, different characteristics in a Wigner-Ville Distribution (WVD) observed for single auto term and cross terms can be simplified to remove any cross-term interference. By selecting time and frequency points of the auto terms signal, the accuracy of BSS can be improved. An experimental simulation has been used, with changes in the pulse width of the transmitted signal, the relative amplitude and the time delay parameter, in order to analyzing the feasibility of this new method. Simulation results show that the new method is not only able to separate rigid scattering components, but can also separate the components when elastic scattering and rigid scattering exist at the same time. Experimental results confirm that the new method can be used in separating the rigid scattering structure of underwater objects.

Mechanistic insights into phosphoprotein-binding FHA domains.

Science.gov (United States)

Liang, Xiangyang; Van Doren, Steven R

2008-08-01

of FHA domains by a bioinformatics approach. The phosphopeptide-dependent dynamics of an FHA domain, SH2 domain, and PTB domain suggest a common theme: rigid, preformed binding surfaces support van der Waals contacts that provide favorable binding enthalpy. Despite the lack of pronounced conformational changes in FHA domains linked to binding events, more subtle adjustments may be possible. In the one FHA domain tested, phosphothreonine peptide binding is accompanied by increased flexibility just outside the binding site and increased rigidity across the beta-sandwich. The folding of the same FHA domain progresses through near-native intermediates that stabilize the recognition loops in the center of the phosphoprotein-binding surface; this may promote rigidity in the interface and affinity for targets phosphorylated on threonine.

A Momentum-Exchange/Fictitious Domain-Lattice Boltzmann Method for Solving Particle Suspensions

Energy Technology Data Exchange (ETDEWEB)

Jeon, Seok Yun; Yoon, Joon Yong [Hanyang Univ., Seoul (Korea, Republic of); Kim, Chul Kyu [Korea Institute of Civil Engineering and Building Technology, Goyang (Korea, Republic of); Shin, Myung Seob [Korea Intellectual Property Office(KIPO), Daejeon (Korea, Republic of)

2016-06-15

This study presents a Lattice Boltzmann Method (LBM) coupled with a momentum-exchange approach/fictitious domain (MEA/FD) method for the simulation of particle suspensions. The method combines the advantages of the LB and the FD methods by using two unrelated meshes, namely, a Eulerian mesh for the flow domain and a Lagrangian mesh for the solid domain. The rigid body conditions are enforced by the momentum-exchange scheme in which the desired value of velocity is imposed directly in the particle inner domain by introducing a pseudo body force to satisfy the constraint of rigid body motion, which is the key idea of a fictitious domain (FD) method. The LB-MEA/FD method has been validated by simulating two different cases, and the results have been compared with those through other methods. The numerical evidence illustrated the capability and robustness of the present method for simulating particle suspensions.

Theory of amorphous ices.

Science.gov (United States)

Limmer, David T; Chandler, David

2014-07-01

We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two amorphous solids. The phase diagram we predict includes a nonequilibrium triple point where two amorphous phases and the liquid coexist. Whereas the amorphous solids are long-lived and slowly aging glasses, their melting can lead quickly to the formation of crystalline ice. Further, melting of the higher density amorphous solid at low pressures takes place in steps, transitioning to the lower-density glass before accessing a nonequilibrium liquid from which ice coarsens.

Si-H bond dynamics in hydrogenated amorphous silicon

Science.gov (United States)

Scharff, R. Jason; McGrane, Shawn D.

2007-08-01

The ultrafast structural dynamics of the Si-H bond in the rigid solvent environment of an amorphous silicon thin film is investigated using two-dimensional infrared four-wave mixing techniques. The two-dimensional infrared (2DIR) vibrational correlation spectrum resolves the homogeneous line shapes ( 4ps waiting times. The Si-H stretching mode anharmonic shift is determined to be 84cm-1 and decreases slightly with vibrational frequency. The 1→2 linewidth increases with vibrational frequency. Frequency dependent vibrational population times measured by transient grating spectroscopy are also reported. The narrow homogeneous line shape, large inhomogeneous broadening, and lack of spectral diffusion reported here present the ideal backdrop for using a 2DIR probe following electronic pumping to measure the transient structural dynamics implicated in the Staebler-Wronski degradation [Appl. Phys. Lett. 31, 292 (1977)] in a-Si:H based solar cells.

Low-frequency magnetization processes in chemically etched Co-based amorphous ribbons

International Nuclear Information System (INIS)

Betancourt, I.; Martinez, L.A.; Valenzuela, R.

2005-01-01

In this report we present a study of the magnetization processes for Co-based amorphous ribbons at low frequencies (10 Hz-13 MHz) as a function of decreasing thicknesses attained by chemical etching. Reversible domain-wall bulging, characterized by initial permeability and relaxation frequency, was monitored by means of inductance measurements. The real part of inductance (proportional to initial permeability) exhibited a decreasing trend with diminishing ribbon thickness, together with an increasing tendency for the relaxation frequency. For high amplitude of the ac field (leading to domain-wall unpinning), reduced ribbon thickness showed a deleterious-enhancement effect on irreversible domain-wall displacement, which was observed for both real and imaginary inductance spectroscopic plots. Results are interpreted in terms of reduced domain-wall pinning distances resulting from thinner alloy samples

Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

Science.gov (United States)

Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

2016-05-03

A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

The two-body problem of a pseudo-rigid body and a rigid sphere

DEFF Research Database (Denmark)

Kristiansen, Kristian Uldall; Vereshchagin, M.; Gózdziewski, K.

2012-01-01

n this paper we consider the two-body problem of a spherical pseudo-rigid body and a rigid sphere. Due to the rotational and "re-labelling" symmetries, the system is shown to possess conservation of angular momentum and circulation. We follow a reduction procedure similar to that undertaken...... in the study of the two-body problem of a rigid body and a sphere so that the computed reduced non-canonical Hamiltonian takes a similar form. We then consider relative equilibria and show that the notions of locally central and planar equilibria coincide. Finally, we show that Riemann's theorem on pseudo......-rigid bodies has an extension to this system for planar relative equilibria....

A multibody motorcycle model with rigid-ring tyres: formulation and validation

Science.gov (United States)

Leonelli, Luca; Mancinelli, Nicolò

2015-06-01

The aim of this paper is the development and validation of a three-dimensional multibody motorcycle model including a rigid-ring tyre model, taking into account both the slopes and elevation of the road surface. In order to achieve accurate assessment of ride and handling performances of a road racing motorcycle, a tyre model capable of reproducing the dynamic response to actual road excitation is required. While a number of vehicle models with such feature are available for car application, the extension to the motorcycle modelling has not been addressed yet. To do so, a novel parametrisation for the general motorcycle kinematics is proposed, using a mixed reference point and relative coordinates approach. The resulting description, developed in terms of dependent coordinates, makes it possible to include the rigid-ring kinematics as well as road elevation and slopes, without affecting computational efficiency. The equations of motion for the whole multibody system are derived symbolically and the constraint equations arising from the dependent coordinate formulation are handled using the position and velocity vector projection technique. The resulting system of equations is integrated in time domain using a standard ordinary differential equation (ODE) algorithm. Finally, the model is validated with respect to experimentally measured data in both time and frequency domains.

Hydrogen in amorphous silicon

International Nuclear Information System (INIS)

Peercy, P.S.

1980-01-01

The structural aspects of amorphous silicon and the role of hydrogen in this structure are reviewed with emphasis on ion implantation studies. In amorphous silicon produced by Si ion implantation of crystalline silicon, the material reconstructs into a metastable amorphous structure which has optical and electrical properties qualitatively similar to the corresponding properties in high-purity evaporated amorphous silicon. Hydrogen studies further indicate that these structures will accomodate less than or equal to 5 at.% hydrogen and this hydrogen is bonded predominantly in a monohydride (SiH 1 ) site. Larger hydrogen concentrations than this can be achieved under certain conditions, but the excess hydrogen may be attributed to defects and voids in the material. Similarly, glow discharge or sputter deposited amorphous silicon has more desirable electrical and optical properties when the material is prepared with low hydrogen concentration and monohydride bonding. Results of structural studies and hydrogen incorporation in amorphous silicon were discussed relative to the different models proposed for amorphous silicon

An amorphous silicon photodiode with 2 THz gain-bandwidth product based on cycling excitation process

Science.gov (United States)

Yan, Lujiang; Yu, Yugang; Zhang, Alex Ce; Hall, David; Niaz, Iftikhar Ahmad; Raihan Miah, Mohammad Abu; Liu, Yu-Hsin; Lo, Yu-Hwa

2017-09-01

Since impact ionization was observed in semiconductors over half a century ago, avalanche photodiodes (APDs) using impact ionization in a fashion of chain reaction have been the most sensitive semiconductor photodetectors. However, APDs have relatively high excess noise, a limited gain-bandwidth product, and high operation voltage, presenting a need for alternative signal amplification mechanisms of superior properties. As an amplification mechanism, the cycling excitation process (CEP) was recently reported in a silicon p-n junction with subtle control and balance of the impurity levels and profiles. Realizing that CEP effect depends on Auger excitation involving localized states, we made the counter intuitive hypothesis that disordered materials, such as amorphous silicon, with their abundant localized states, can produce strong CEP effects with high gain and speed at low noise, despite their extremely low mobility and large number of defects. Here, we demonstrate an amorphous silicon low noise photodiode with gain-bandwidth product of over 2 THz, based on a very simple structure. This work will impact a wide range of applications involving optical detection because amorphous silicon, as the primary gain medium, is a low-cost, easy-to-process material that can be formed on many kinds of rigid or flexible substrates.

Non-rigid ultrasound image registration using generalized relaxation labeling process

Science.gov (United States)

Lee, Jong-Ha; Seong, Yeong Kyeong; Park, MoonHo; Woo, Kyoung-Gu; Ku, Jeonghun; Park, Hee-Jun

2013-03-01

This research proposes a novel non-rigid registration method for ultrasound images. The most predominant anatomical features in medical images are tissue boundaries, which appear as edges. In ultrasound images, however, other features can be identified as well due to the specular reflections that appear as bright lines superimposed on the ideal edge location. In this work, an image's local phase information (via the frequency domain) is used to find the ideal edge location. The generalized relaxation labeling process is then formulated to align the feature points extracted from the ideal edge location. In this work, the original relaxation labeling method was generalized by taking n compatibility coefficient values to improve non-rigid registration performance. This contextual information combined with a relaxation labeling process is used to search for a correspondence. Then the transformation is calculated by the thin plate spline (TPS) model. These two processes are iterated until the optimal correspondence and transformation are found. We have tested our proposed method and the state-of-the-art algorithms with synthetic data and bladder ultrasound images of in vivo human subjects. Experiments show that the proposed method improves registration performance significantly, as compared to other state-of-the-art non-rigid registration algorithms.

Amorphous nanophotonics

CERN Document Server

Scharf, Toralf

2013-01-01

This book represents the first comprehensive overview over amorphous nano-optical and nano-photonic systems. Nanophotonics is a burgeoning branch of optics that enables many applications by steering the mould of light on length scales smaller than the wavelength with devoted nanostructures. Amorphous nanophotonics exploits self-organization mechanisms based on bottom-up approaches to fabricate nanooptical systems. The resulting structures presented in the book are characterized by a deterministic unit cell with tailored geometries; but their spatial arrangement is not controlled. Instead of periodic, the structures appear either amorphous or random. The aim of this book is to discuss all aspects related to observable effects in amorphous nanophotonic material and aspects related to their design, fabrication, characterization and integration into applications. The book has an interdisciplinary nature with contributions from scientists in physics, chemistry and materials sciences and sheds light on the topic fr...

Rigid Body Sampling and Individual Time Stepping for Rigid-Fluid Coupling of Fluid Simulation

Directory of Open Access Journals (Sweden)

Xiaokun Wang

2017-01-01

Full Text Available In this paper, we propose an efficient and simple rigid-fluid coupling scheme with scientific programming algorithms for particle-based fluid simulation and three-dimensional visualization. Our approach samples the surface of rigid bodies with boundary particles that interact with fluids. It contains two procedures, that is, surface sampling and sampling relaxation, which insures uniform distribution of particles with less iterations. Furthermore, we present a rigid-fluid coupling scheme integrating individual time stepping to rigid-fluid coupling, which gains an obvious speedup compared to previous method. The experimental results demonstrate the effectiveness of our approach.

Rigidly foldable origami gadgets and tessellations

Science.gov (United States)

Evans, Thomas A.; Lang, Robert J.; Magleby, Spencer P.; Howell, Larry L.

2015-01-01

Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented. PMID:26473037

Three-dimensional nanomechanical mapping of amorphous and crystalline phase transitions in phase-change materials.

Science.gov (United States)

Grishin, Ilja; Huey, Bryan D; Kolosov, Oleg V

2013-11-13

The nanostructure of micrometer-sized domains (bits) in phase-change materials (PCM) that undergo switching between amorphous and crystalline phases plays a key role in the performance of optical PCM-based memories. Here, we explore the dynamics of such phase transitions by mapping PCM nanostructures in three dimensions with nanoscale resolution by combining precision Ar ion beam cross-sectional polishing and nanomechanical ultrasonic force microscopy (UFM) mapping. Surface and bulk phase changes of laser written submicrometer to micrometer sized amorphous-to-crystalline (SET) and crystalline-to-amorphous (RESET) bits in chalcogenide Ge2Sb2Te5 PCM are observed with 10-20 nm lateral and 4 nm depth resolution. UFM mapping shows that the Young's moduli of crystalline SET bits exceed the moduli of amorphous areas by 11 ± 2%, with crystalline content extending from a few nanometers to 50 nm in depth depending on the energy of the switching pulses. The RESET bits written with 50 ps pulses reveal shallower depth penetration and show 30-50 nm lateral and few nanometer vertical wavelike topography that is anticorrelated with the elastic modulus distribution. Reverse switching of amorphous RESET bits results in the full recovery of subsurface nanomechanical properties accompanied with only partial topography recovery, resulting in surface corrugations attributed to quenching. This precision sectioning and nanomechanical mapping approach could be applicable to a wide range of amorphous, nanocrystalline, and glass-forming materials for 3D nanomechanical mapping of amorphous-crystalline transitions.

Rigid Residue Scan Simulations Systematically Reveal Residue Entropic Roles in Protein Allostery.

Directory of Open Access Journals (Sweden)

Robert Kalescky

2016-04-01

Full Text Available Intra-protein information is transmitted over distances via allosteric processes. This ubiquitous protein process allows for protein function changes due to ligand binding events. Understanding protein allostery is essential to understanding protein functions. In this study, allostery in the second PDZ domain (PDZ2 in the human PTP1E protein is examined as model system to advance a recently developed rigid residue scan method combining with configurational entropy calculation and principal component analysis. The contributions from individual residues to whole-protein dynamics and allostery were systematically assessed via rigid body simulations of both unbound and ligand-bound states of the protein. The entropic contributions of individual residues to whole-protein dynamics were evaluated based on covariance-based correlation analysis of all simulations. The changes of overall protein entropy when individual residues being held rigid support that the rigidity/flexibility equilibrium in protein structure is governed by the La Châtelier's principle of chemical equilibrium. Key residues of PDZ2 allostery were identified with good agreement with NMR studies of the same protein bound to the same peptide. On the other hand, the change of entropic contribution from each residue upon perturbation revealed intrinsic differences among all the residues. The quasi-harmonic and principal component analyses of simulations without rigid residue perturbation showed a coherent allosteric mode from unbound and bound states, respectively. The projection of simulations with rigid residue perturbation onto coherent allosteric modes demonstrated the intrinsic shifting of ensemble distributions supporting the population-shift theory of protein allostery. Overall, the study presented here provides a robust and systematic approach to estimate the contribution of individual residue internal motion to overall protein dynamics and allostery.

A comparative study of velocity increment generation between the rigid body and flexible models of MMET

Energy Technology Data Exchange (ETDEWEB)

Ismail, Norilmi Amilia, E-mail: aenorilmi@usm.my [School of Aerospace Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia)

2016-02-01

The motorized momentum exchange tether (MMET) is capable of generating useful velocity increments through spin–orbit coupling. This study presents a comparative study of the velocity increments between the rigid body and flexible models of MMET. The equations of motions of both models in the time domain are transformed into a function of true anomaly. The equations of motion are integrated, and the responses in terms of the velocity increment of the rigid body and flexible models are compared and analysed. Results show that the initial conditions, eccentricity, and flexibility of the tether have significant effects on the velocity increments of the tether.

Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

KAUST Repository

Chaieb, Sahraoui

2015-04-09

Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

KAUST Repository

Chaieb, Saharoui; Mughal, Asad Jahangir

2015-01-01

Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

Tile-based rigidization surface parametric design study

Science.gov (United States)

Giner Munoz, Laura; Luntz, Jonathan; Brei, Diann; Kim, Wonhee

2018-03-01

Inflatable technologies have proven useful in consumer goods as well as in more recent applications including civil structures, aerospace, medical, and robotics. However, inflatable technologies are typically lacking in their ability to provide rigid structural support. Particle jamming improves upon this by providing structures which are normally flexible and moldable but become rigid when air is removed. Because these are based on an airtight bladder filled with loose particles, they always occupy the full volume of its rigid state, even when not rigidized. More recent developments in layer jamming have created thin, compact rigidizing surfaces replacing the loose volume of particles with thinly layered surface materials. Work in this area has been applied to several specific applications with positive results but have not generally provided the broader understanding of the rigidization performance as a function of design parameters required for directly adapting layer rigidization technology to other applications. This paper presents a parametric design study of a new layer jamming vacuum rigidization architecture: tile-based vacuum rigidization. This form of rigidization is based on layers of tiles contained within a thin vacuum bladder which can be bent, rolled, or otherwise compactly stowed, but when deployed flat, can be vacuumed and form a large, flat, rigid plate capable of supporting large forces both localized and distributed over the surface. The general architecture and operation detailing rigidization and compliance mechanisms is introduced. To quantitatively characterize the rigidization behavior, prototypes rigidization surfaces are fabricated and an experimental technique is developed based on a 3-point bending test. Performance evaluation metrics are developed to describe the stiffness, load-bearing capacity, and internal slippage of tested prototypes. A set of experimental parametric studies are performed to better understand the impact of

Domain walls dynamics in the amorphous ribbon with a helical magnetic anisotropy

International Nuclear Information System (INIS)

Zhmetko, D.N.; Savin, V.V.; Lemish, P.V.; Troschenkov, Y.N.

2006-01-01

The damping mechanism for motion of domain walls, which form the sandwich structure and move from the middle plane of the ribbon to opposite surfaces during the dynamic magnetization reversal, have been investigated. The difference between the real and ideal sandwich domain structure, the actual distribution of the anisotropy easy directions through the ribbon thickness and the M-bar s deviation from local easy directions under the action of applied magnetic field have been taken into account. It was revealed that the maximum of the total damping coefficient β tot (x) near the half-way of the domain wall run is due to the influence of the magnetic stray fields. These fields have a character of irregular oscillations and are directed approximately perpendicular to the local easy direction of the ribbon layer through which the domain wall propagates. The damping coefficient β e.c. (x) determined by eddy-currents has the maximal value close to the ribbon middle and decreases linearly to zero when the domain wall approaches the ribbon surface

Chemical bonding modifications of tetrahedral amorphous carbon and nitrogenated tetrahedral amorphous carbon films induced by rapid thermal annealing

International Nuclear Information System (INIS)

McCann, R.; Roy, S.S.; Papakonstantinou, P.; Bain, M.F.; Gamble, H.S.; McLaughlin, J.A.

2005-01-01

Tetrahedral amorphous carbon (ta-C) and nitrogenated tetrahedral amorphous carbon films (ta-CN x ), deposited by double bend off plane Filtered Vacuum Cathodic Arc were annealed up to 1000 deg. C in flowing argon for 2 min. Modifications on the chemical bonding structure of the rapidly annealed films, as a function of temperature, were investigated by NEXAFS, X-ray photoelectron and Raman spectroscopies. The interpretation of these spectra is discussed. The results demonstrate that the structure of undoped ta-C films prepared at floating potential with an arc current of 80 A remains stable up to 900 deg. C, whereas that of ta-CN x containing 12 at.% nitrogen is stable up to 700 deg. C. At higher temperatures, all the spectra indicated the predominant formation of graphitic carbon. Through NEXAFS studies, we clearly observed three π* resonance peaks at the ' N K edge structure. The origin of these three peaks is not well established in the literature. However our temperature-dependant study ascertained that the first peak originates from C=N bonds and the third peak originates from the incorporation of nitrogen into the graphite like domains

Ion implantation and amorphous metals

International Nuclear Information System (INIS)

Hohmuth, K.; Rauschenbach, B.

1981-01-01

This review deals with ion implantation of metals in the high concentration range for preparing amorphous layers (>= 10 at%, implantation doses > 10 16 ions/cm 2 ). Different models are described concerning formation of amorphous phases of metals by ion implantation and experimental results are given. The study of amorphous phases has been carried out by the aid of Rutherford backscattering combined with the channeling technique and using transmission electron microscopy. The structure of amorphous metals prepared by ion implantation has been discussed. It was concluded that amorphous metal-metalloid compounds can be described by a dense-random-packing structure with a great portion of metal atoms. Ion implantation has been compared with other techniques for preparing amorphous metals and the adventages have been outlined

Rigidity and symmetry

CERN Document Server

Weiss, Asia; Whiteley, Walter

2014-01-01

This book contains recent contributions to the fields of rigidity and symmetry with two primary focuses: to present the mathematically rigorous treatment of rigidity of structures, and to explore the interaction of geometry, algebra, and combinatorics. Overall, the book shows how researchers from diverse backgrounds explore connections among the various discrete structures with symmetry as the unifying theme.  Contributions present recent trends and advances in discrete geometry, particularly in the theory of polytopes. The rapid development of abstract polytope theory has resulted in a rich theory featuring an attractive interplay of methods and tools from discrete geometry, group theory, classical geometry, hyperbolic geometry and topology.  The volume will also be a valuable source as an introduction to the ideas of both combinatorial and geometric rigidity theory and its applications, incorporating the surprising impact of symmetry. It will appeal to students at both the advanced undergraduate and gradu...

CFA Films in Amorphous Substrate: Structural Phase Induction and Magnetization Dynamics

Science.gov (United States)

Correa, M. A.; Bohn, F.; Escobar, V. M.

We report a systematic study of the structural and quasi-static magnetic properties, as well as of the dynamic magnetic response through MI effect, in Co2FeAl and MgO//Co2FeAl single layers and a MgO//Co2FeAl/Ag/Co2FeAl trilayered film, all grown onto an amorphous substrate. We present a new route to induce the crystalline structure in the Co2FeAl alloy and verify that changes in the structural phase of this material leads to remarkable modifications of the magnetic anisotropy and, consequently, dynamic magnetic behavior. Considering the electrical and magnetic properties of the Co2FeAl, our results open new possibilities for technological applications of this full-Heusler alloy in rigid and flexible spintronic devices.

Corrosion resistance of Fe-based amorphous alloys

International Nuclear Information System (INIS)

Botta, W.J.; Berger, J.E.; Kiminami, C.S.; Roche, V.; Nogueira, R.P.; Bolfarini, C.

2014-01-01

Highlights: ► We report corrosion properties of Fe-based amorphous alloys in different media. ► The Cr-containing alloys had corrosion resistance close to that of Pt in all media. ► The wide range of electrochemical stability is relevant in many industrial domains. -- Abstract: Fe-based amorphous alloys can be designed to present an attractive combination of properties with high corrosion resistance and high mechanical strength. Such properties are clearly adequate for their technological use as coatings, for example, in steel pipes. In this work, we studied the corrosion properties of amorphous ribbons of the following Fe-based compositions: Fe 66 B 30 Nb 4 , [(Fe 0.6 Co 0.4 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , [(Fe 0.7 Co 0.3 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , Fe 56 Cr 23 Ni 5.7 B 16 , Fe 53 Cr 22 Ni 5.6 B 19 and Fe 50 Cr 22 Ni 5.4 B 23 . The ribbons were obtained by rapid solidification using the melt-spinning process, and were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and optical (OM) and scanning electron microscopy (SEM). The corrosion properties were evaluated by corrosion potential survey and potentiodynamic polarization. The Cr containing alloys, that is the FeCrNiB type of alloys, showed the best corrosion resistance properties with the formation of a stable passive film that ensured a very large passivation plateau

Birationally rigid varieties

CERN Document Server

Pukhlikov, Aleksandr

2013-01-01

Birational rigidity is a striking and mysterious phenomenon in higher-dimensional algebraic geometry. It turns out that certain natural families of algebraic varieties (for example, three-dimensional quartics) belong to the same classification type as the projective space but have radically different birational geometric properties. In particular, they admit no non-trivial birational self-maps and cannot be fibred into rational varieties by a rational map. The origins of the theory of birational rigidity are in the work of Max Noether and Fano; however, it was only in 1970 that Iskovskikh and Manin proved birational superrigidity of quartic three-folds. This book gives a systematic exposition of, and a comprehensive introduction to, the theory of birational rigidity, presenting in a uniform way, ideas, techniques, and results that so far could only be found in journal papers. The recent rapid progress in birational geometry and the widening interaction with the neighboring areas generate the growing interest ...

In situ observation of magnetic vortex manipulation by external fields in amorphous CeFeB ribbon

International Nuclear Information System (INIS)

Zuo, Shulan; Zhang, Ming; Li, Rui; Zhang, Ying; Peng, Licong; Xiong, Jiefu; Liu, Dan; Zhao, Tongyun; Hu, Fengxia; Shen, Baogen; Sun, Jirong

2017-01-01

In this study, we show the real-space observation of the magnetic domain configuration in amorphous Ce 14 Fe 80 B 6 ribbon using Lorentz transmission electron microscopy. Cross-tie domain walls composed of magnetic vortices (Vs) and antivortices (AVs) are observed. The evolution of Vs/AVs manipulated by temperature, in-plane magnetic field, and electrical current is clearly demonstrated. Magnetic V nucleation and annihilation in pair are observed because of the stimulus of external fields.

Corrosion resistant amorphous metals and methods of forming corrosion resistant amorphous metals

Science.gov (United States)

Farmer, Joseph C [Tracy, CA; Wong, Frank M. G. [Livermore, CA; Haslam, Jeffery J [Livermore, CA; Yang, Nancy [Lafayette, CA; Lavernia, Enrique J [Davis, CA; Blue, Craig A [Knoxville, TN; Graeve, Olivia A [Reno, NV; Bayles, Robert [Annandale, VA; Perepezko, John H [Madison, WI; Kaufman, Larry [Brookline, MA; Schoenung, Julie [Davis, CA; Ajdelsztajn, Leo [Walnut Creek, CA

2009-11-17

A system for coating a surface comprises providing a source of amorphous metal, providing ceramic particles, and applying the amorphous metal and the ceramic particles to the surface by a spray. The coating comprises a composite material made of amorphous metal that contains one or more of the following elements in the specified range of composition: yttrium (.gtoreq.1 atomic %), chromium (14 to 18 atomic %), molybdenum (.gtoreq.7 atomic %), tungsten (.gtoreq.1 atomic %), boron (.ltoreq.5 atomic %), or carbon (.gtoreq.4 atomic %).

Positrons in amorphous alloys

International Nuclear Information System (INIS)

Moser, Pierre.

1981-07-01

Positron annihilation techniques give interesting informations about ''empty spaces'' in amorphous alloys. The results of an extensive research work on the properties of either pre-existing or irradiation induced ''empty spaces'' in four amorphous alloys are presented. The pre-existing empty spaces appear to be small vacancy-like defects. The irradiation induced defects are ''close pairs'' with widely distributed configurations. There is a strong interaction between vacancy like and interstitial like components. A model is proposed, which explains the radiation resistance mechanism of the amorphous alloys. An extensive joint research work to study four amorphous alloys, Fe 80 B 20 ,Fe 40 Ni 40 P 14 B 6 , Cu 50 Ti 50 , Pd 80 Si 20 , is summarized

Rigidity-tuning conductive elastomer

Science.gov (United States)

Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel

2015-06-01

We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE-PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ˜6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE-PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE-PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation.

Rigidity-tuning conductive elastomer

International Nuclear Information System (INIS)

Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel

2015-01-01

We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE–PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ∼6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE–PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE–PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation. (paper)

On flexible and rigid nouns

DEFF Research Database (Denmark)

Rijkhoff, Jan

2010-01-01

classes. Finally this article wants to claim that the distinction between rigid and flexible noun categories (a) adds a new dimension to current classifications of parts of speech systems, (b) correlates with certain grammatical phenomena (e.g. so-called number discord), and (c) helps to explain the parts......This article argues that in addition to the major flexible lexical categories in Hengeveld’s classification of parts of speech systems (Contentive, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members...... by the flexible item in the external world. I will then argue that flexible word classes constitute a proper category (i.e. they are not the result of a merger of some rigid word classes) in that members of flexible word categories display the same properties regarding category membership as members of rigid word...

The photoexcitation of crystalline ice and amorphous solid water: A molecular dynamics study of outcomes at 11 K and 125 K

Energy Technology Data Exchange (ETDEWEB)

Crouse, J.; Loock, H.-P., E-mail: hploock@chem.queensu.ca; Cann, N. M., E-mail: ncann@chem.queensu.ca [Department of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6 (Canada)

2015-07-21

Photoexcitation of crystalline ice Ih and amorphous solid water at 7-9 eV is examined using molecular dynamics simulations and a fully flexible water model. The probabilities of photofragment desorption, trapping, and recombination are examined for crystalline ice at 11 K and at 125 K and for amorphous solid water at 11 K. For 11 K crystalline ice, a fully rigid water model is also employed for comparison. The kinetic energy of desorbed H atoms and the distance travelled by trapped fragments are correlated to the location and the local environment of the photoexcited water molecule. In all cases, H atom desorption is found to be the most likely outcome in the top bilayer while trapping of all photofragments is most probable deeper in the solid where the likelihood for recombination of the fragments into H{sub 2}O molecules also rises. Trajectory analysis indicates that the local hydrogen bonding network in amorphous solid water is more easily distorted by a photodissociation event compared to crystalline ice. Also, simulations indicate that desorption of OH radicals and H{sub 2}O molecules are more probable in amorphous solid water. The kinetic energy distributions for desorbed H atoms show a peak at high energy in crystalline ice, arising from photoexcited water molecules in the top monolayer. This peak is less pronounced in amorphous solid water. H atoms that are trapped may be displaced by up to ∼10 water cages, but migrate on average 3 water cages. Trapped OH fragments tend to stay near the original solvent cage.

CT-3DRA registration for radiosurgery treatments: a comparison among rigid, affine and non rigid approaches

International Nuclear Information System (INIS)

Stancanello, J.; Loeckx, D.; Francescon, P.; Calvedon, C.; Avanzo, M.; Cora, S.; Scalchi, P.; Cerveri, P.; Ferrigno, G.

2004-01-01

This work aims at comparing rigid, affine and Local Non Rigid (LNR) CT-3D Rotational Angiography (CT-3DRA) registrations based on mutual information. 10 cranial and 1 spinal cases have been registered by rigid and affine transformations; while LNR has been applied to the cases where residual deformation must be corrected. An example of CT-3DRA registration without regularization term and an example of LNR using the similarity criterion and the regularization term as well as 3D superposition of the 3DRA before and after the registration without the regularization term are presented. All the registrations performed by rigid transformation converged to an acceptable solution. The results about the robustness test in axial direction are reported. Conclusions: For cranial cases, affine transformation endowed with threshold-segmentation pre-processing can be considered the most favourable solution for almost all registrations; for some cases, LNR provides more accurate results. For the spinal case rigid transformation is the most suitable when immobilizing patient during examinations; in this case the increase of accuracy by using LNR registrations seems to be not significant

Magnetic force microscopy: advanced technique for the observation of magnetic domains

International Nuclear Information System (INIS)

Asenjo, A.; Garcia, J. M.; Vazquez, M.

2001-01-01

An overview on the Magnetic Force Microscopy, MFM, as an advanced technique to observe magnetic domains and walls is displayed. Basic concepts are first introduced on the domain structure formation as well as on other techniques to observe magnetic domains. Afterwards, the MFM instrumentation is described making also an emphasis in micro magnetic consideration to interpret the images. Finally, a set of selected advanced magnetic materials with different domain structures is chosen to show the wide possibilities of this techniques to characterise the surface magnetic behaviour. The domain structure of materials as commercial magnetic recording media, thin films and multilayers, amorphous micro tubes, nanocrystalline ribbons, perovskites or magnetic nano wires is shown. (Author) 16 refs

Structural amorphous steels

International Nuclear Information System (INIS)

Lu, Z.P.; Liu, C.T.; Porter, W.D.; Thompson, J.R.

2004-01-01

Recent advancement in bulk metallic glasses, whose properties are usually superior to their crystalline counterparts, has stimulated great interest in fabricating bulk amorphous steels. While a great deal of effort has been devoted to this field, the fabrication of structural amorphous steels with large cross sections has remained an alchemist's dream because of the limited glass-forming ability (GFA) of these materials. Here we report the discovery of structural amorphous steels that can be cast into glasses with large cross-section sizes using conventional drop-casting methods. These new steels showed interesting physical, magnetic, and mechanical properties, along with high thermal stability. The underlying mechanisms for the superior GFA of these materials are discussed

Thermomagnetically written domains in TbFeCo thin films

International Nuclear Information System (INIS)

Reim, W.; Weller, D.

1988-01-01

Characteristic features of thermomagnetically written domains in amorphous Tb x (Fe 90 Co 10 ) 100-x alloy thin films having different magnetic properties are reported. In particular, the writing process in materials with low Tb content chi ≤ 21 dominated by the demagnetizing field is compared to the bias field dominated process in Tb rich samples 22 ≤ chi ≤ 25. Domain wall movement over lateral dimensions of the bit size is found for Tb poor materials while for chi ≥ 22 domain boundaries are primarily determined by the area heated up to the Curie-temperature. The importance of mechanical stress on domain formation and irreversible changes of the storage medium due to overheating in the writing process are reported

Flexible and rigid cystoscopy in women.

Science.gov (United States)

Gee, Jason R; Waterman, Bradley J; Jarrard, David F; Hedican, Sean P; Bruskewitz, Reginald C; Nakada, Stephen Y

2009-01-01

Previous studies have evaluated the tolerability of rigid versus flexible cystoscopy in men. Similar studies, however, have not been performed in women. We sought to determine whether office-based flexible cystoscopy was better tolerated than rigid cystoscopy in women. Following full IRB approval, women were prospectively randomized in a single-blind manner. Patients were randomized to flexible or rigid cystoscopy and draped in the lithotomy position to maintain blinding of the study. Questionnaires evaluated discomfort before, during, and after cystoscopy. Thirty-six women were randomized to flexible (18) or rigid (18) cystoscopy. Indications were surveillance (16), hematuria (15), recurrent UTIs (2), voiding dysfunction (1), and other (2). All questionnaires were returned by 31/36 women. Using a 10-point visual analog scale (VAS), median discomfort during the procedure for flexible and rigid cystoscopy were 1.4 and 1.8, respectively, in patients perceiving pain. Median recalled pain 1 week later was similar at 0.8 and 1.15, respectively. None of these differences were statistically significant. Flexible and rigid cystoscopy are well tolerated in women. Discomfort during and after the procedure is minimal in both groups. Urologists should perform either procedure in women based on their preference and skill level.

Vision based tunnel inspection using non-rigid registration

Science.gov (United States)

Badshah, Amir; Ullah, Shan; Shahzad, Danish

2015-04-01

Growing numbers of long tunnels across the globe has increased the need for safety measurements and inspections of tunnels in these days. To avoid serious damages, tunnel inspection is highly recommended at regular intervals of time to find any deformations or cracks at the right time. While following the stringent safety and tunnel accessibility standards, conventional geodetic surveying using techniques of civil engineering and other manual and mechanical methods are time consuming and results in troublesome of routine life. An automatic tunnel inspection by image processing techniques using non rigid registration has been proposed. There are many other image processing methods used for image registration purposes. Most of the processes are operation of images in its spatial domain like finding edges and corners by Harris edge detection method. These methods are quite time consuming and fail for some or other reasons like for blurred or images with noise. Due to use of image features directly by these methods in the process, are known by the group, correlation by image features. The other method is featureless correlation, in which the images are converted into its frequency domain and then correlated with each other. The shift in spatial domain is the same as in frequency domain, but the processing is order faster than in spatial domain. In the proposed method modified normalized phase correlation has been used to find any shift between two images. As pre pre-processing the tunnel images i.e. reference and template are divided into small patches. All these relative patches are registered by the proposed modified normalized phase correlation. By the application of the proposed algorithm we get the pixel movement of the images. And then these pixels shifts are converted to measuring units like mm, cm etc. After the complete process if there is any shift in the tunnel at described points are located.

Characterization of Amorphous and Co-Amorphous Simvastatin Formulations Prepared by Spray Drying

Directory of Open Access Journals (Sweden)

Goedele Craye

2015-12-01

Full Text Available In this study, spray drying from aqueous solutions, using the surface-active agent sodium lauryl sulfate (SLS as a solubilizer, was explored as a production method for co-amorphous simvastatin–lysine (SVS-LYS at 1:1 molar mixtures, which previously have been observed to form a co-amorphous mixture upon ball milling. In addition, a spray-dried formulation of SVS without LYS was prepared. Energy-dispersive X-ray spectroscopy (EDS revealed that SLS coated the SVS and SVS-LYS particles upon spray drying. X-ray powder diffraction (XRPD and differential scanning calorimetry (DSC showed that in the spray-dried formulations the remaining crystallinity originated from SLS only. The best dissolution properties and a “spring and parachute” effect were found for SVS spray-dried from a 5% SLS solution without LYS. Despite the presence of at least partially crystalline SLS in the mixtures, all the studied formulations were able to significantly extend the stability of amorphous SVS compared to previous co-amorphous formulations of SVS. The best stability (at least 12 months in dry conditions was observed when SLS was spray-dried with SVS (and LYS. In conclusion, spray drying of SVS and LYS from aqueous surfactant solutions was able to produce formulations with improved physical stability for amorphous SVS.

Characterization of Amorphous and Co-Amorphous Simvastatin Formulations Prepared by Spray Drying.

Science.gov (United States)

Craye, Goedele; Löbmann, Korbinian; Grohganz, Holger; Rades, Thomas; Laitinen, Riikka

2015-12-03

In this study, spray drying from aqueous solutions, using the surface-active agent sodium lauryl sulfate (SLS) as a solubilizer, was explored as a production method for co-amorphous simvastatin-lysine (SVS-LYS) at 1:1 molar mixtures, which previously have been observed to form a co-amorphous mixture upon ball milling. In addition, a spray-dried formulation of SVS without LYS was prepared. Energy-dispersive X-ray spectroscopy (EDS) revealed that SLS coated the SVS and SVS-LYS particles upon spray drying. X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) showed that in the spray-dried formulations the remaining crystallinity originated from SLS only. The best dissolution properties and a "spring and parachute" effect were found for SVS spray-dried from a 5% SLS solution without LYS. Despite the presence of at least partially crystalline SLS in the mixtures, all the studied formulations were able to significantly extend the stability of amorphous SVS compared to previous co-amorphous formulations of SVS. The best stability (at least 12 months in dry conditions) was observed when SLS was spray-dried with SVS (and LYS). In conclusion, spray drying of SVS and LYS from aqueous surfactant solutions was able to produce formulations with improved physical stability for amorphous SVS.

Influence of Weak External Magnetic Field on Amorphous and Nanocrystalline Fe-based Alloys

Science.gov (United States)

Degmová, J.; Sitek, J.

2010-07-01

Nanoperm, Hitperm and Finamet amorphous and nanocrystalline alloys were measured by Mössbauer spectrometry in a weak external magnetic field of 0.5 T. It was shown that the most sensitive parameters of Mössbauer spectra are the intensities of the 2nd and the 5th lines. Rather small changes were observed also in the case of internal magnetic field values. The spectrum of nanocrystalline Nanoperm showed the increase in A23 parameter (ratio of line intensities) from 2.4 to 3.7 and decrease of internal magnetic field from 20 to 19 T for amorphous subspectrum under the influence of magnetic field. Spectrum of nanocrystalline Finemet shown decrease in A23 parameter from 3.5 to 2.6 almost without a change in the internal magnetic field value. In the case of amorphous Nanoperm and Finemet samples, the changes are almost negligible. Hitperm alloy showed the highest sensitivity to the weak magnetic field, when the A23 parameter increased from 0.4 to 2.5 in the external magnetic fields. The A23 parameter of crystalline subspectrum increased from 2.7 to 3.8 and the value of internal magnetic field corresponding to amorphous subspectrum increased from 22 to 24 T. The behavior of nanocrystalline alloys under weak external magnetic field was analyzed within the three-level relaxation model of magnetic dynamics in an assembly of single-domain particles.

Hydrogen in disordered and amorphous solids

International Nuclear Information System (INIS)

Bambakidis, G; Bowman, R.C.

1986-01-01

This book presents information on the following topoics: elements of the theory of amorphous semiconductors; electronic structure of alpha-SiH; fluctuation induced gap states in amorphous hydrogenated silicon; hydrogen on semiconductor surfaces; the influence of hydrogen on the defects and instabilities in hydrogenated amorphous silicon; deuteron magnetic resonance in some amorphous semiconductors; formation of amorphous metals by solid state reactions of hydrogen with an intermetallic compound; NMR studies of the hydrides of disordered and amorphous alloys; neutron vibrational spectroscopy of disordered metal-hydrogen system; dynamical disorder of hydrogen in LaNi /SUB 5-y/ M /SUB y/ hydrides studied by quasi-elastic neutron scattering; recent studies of intermetallic hydrides; tritium in Pd and Pd /SUB 0.80/ Sg /SUB 0.20/ ; and determination of hydrogen concentration in thin films of absorbing materials

Analysis of Switched-Rigid Floating Oscillator

Directory of Open Access Journals (Sweden)

Prabhakar R. Marur

2009-01-01

Full Text Available In explicit finite element simulations, a technique called deformable-to-rigid (D2R switching is used routinely to reduce the computation time. Using the D2R option, the deformable parts in the model can be switched to rigid and reverted back to deformable when needed during the analysis. The time of activation of D2R however influences the overall dynamics of the system being analyzed. In this paper, a theoretical basis for the selection of time of rigid switching based on system energy is established. A floating oscillator problem is investigated for this purpose and closed-form analytical expressions are derived for different phases in rigid switching. The analytical expressions are validated by comparing the theoretical results with numerical computations.

Fundamentals of amorphous solids structure and properties

CERN Document Server

Stachurski, Zbigniew H

2014-01-01

Long awaited, this textbook fills the gap for convincing concepts to describe amorphous solids. Adopting a unique approach, the author develops a framework that lays the foundations for a theory of amorphousness. He unravels the scientific mysteries surrounding the topic, replacing rather vague notions of amorphous materials as disordered crystalline solids with the well-founded concept of ideal amorphous solids. A classification of amorphous materials into inorganic glasses, organic glasses, glassy metallic alloys, and thin films sets the scene for the development of the model of ideal amorph

Physics of amorphous metals

CERN Document Server

Kovalenko, Nikolai P; Krey, Uwe

2008-01-01

The discovery of bulk metallic glasses has led to a large increase in the industrial importance of amorphous metals, and this is expected to continue. This book is the first to describe the theoretical physics of amorphous metals, including the important theoretical development of the last 20 years.The renowned authors stress the universal aspects in their description of the phonon or magnon low-energy excitations in the amorphous metals, e.g. concerning the remarkable consequences of the properties of these excitations for the thermodynamics at low and intermediate temperatures. Tunneling

Amorphous nanoparticles — Experiments and computer simulations

International Nuclear Information System (INIS)

Hoang, Vo Van; Ganguli, Dibyendu

2012-01-01

The data obtained by both experiments and computer simulations concerning the amorphous nanoparticles for decades including methods of synthesis, characterization, structural properties, atomic mechanism of a glass formation in nanoparticles, crystallization of the amorphous nanoparticles, physico-chemical properties (i.e. catalytic, optical, thermodynamic, magnetic, bioactivity and other properties) and various applications in science and technology have been reviewed. Amorphous nanoparticles coated with different surfactants are also reviewed as an extension in this direction. Much attention is paid to the pressure-induced polyamorphism of the amorphous nanoparticles or amorphization of the nanocrystalline counterparts. We also introduce here nanocomposites and nanofluids containing amorphous nanoparticles. Overall, amorphous nanoparticles exhibit a disordered structure different from that of corresponding bulks or from that of the nanocrystalline counterparts. Therefore, amorphous nanoparticles can have unique physico-chemical properties differed from those of the crystalline counterparts leading to their potential applications in science and technology.

Domain-wall dynamics in glass-coated magnetic microwires

International Nuclear Information System (INIS)

Varga, R.; Zhukov, A.; Usov, N.; Blanco, J.M.; Gonzalez, J.; Zhukova, V.; Vojtanik, P.

2007-01-01

Glass-coated magnetic microwires with positive magnetostriction show peculiar domain structure that consists mostly of one large domain with magnetization-oriented axially. It was shown that small closure domains appear at the end of the microwire in order to decrease the stray fields. As a result of such domain structure, the magnetization reversal in axial direction runs through the depinning of one of such closure domains and subsequent propagation of the corresponding domain wall. Quite unusual domain-wall (DW) dynamics of the DW propagation predicted previously from the theory has been found in such amorphous microwires. In this paper, we are dealing with the DW dynamics of glass-coated microwires with small positive magnetostriction. The DW damping coming from the structural relaxation dominates at low temperatures as a result of the decrease of the mobility of the structural atomic-level defects. Negative critical propagation field points to the possible DW propagation without applied magnetic field. Probable explanation could be in terms of the effective mass of the DW

Research Progress on Fe-based Amorphous Coatings

Directory of Open Access Journals (Sweden)

LIANG Xiu-bing

2017-09-01

Full Text Available The latest research progresses on Fe-based amorphous coatings were reviewed. The typical alloy system and the classification of Fe-based amorphous coatings were clarified. The status, progress and development of the Fe-based amorphous coatings prepared by thermal spray processing and laser cladding process were discussed. The main mechanical properties and potential applications of the Fe-based amorphous coatings were also described. Furthermore, based on the main problems mentioned above, the future development of the Fe-based amorphous coatings was discussed, including the exploitation preparation technologies of high amorphous content of the Fe-based coatings, the development of the low cost and high performance Fe-based coating alloys system, the broadening application of Fe-based amorphous coatings, and so on.

Amorphous drugs and dosage forms

DEFF Research Database (Denmark)

Grohganz, Holger; Löbmann, K.; Priemel, P.

2013-01-01

The transformation to an amorphous form is one of the most promising approaches to address the low solubility of drug compounds, the latter being an increasing challenge in the development of new drug candidates. However, amorphous forms are high energy solids and tend to recry stallize. New...... formulation principles are needed to ensure the stability of amorphous drug forms. The formation of solid dispersions is still the most investigated approach, but additional approaches are desirable to overcome the shortcomings of solid dispersions. Spatial separation by either coating or the use of micro-containers...... before single molecules are available for the formation of crystal nuclei, thus stabilizing the amorphous form....

Influence of torsion and tensile stress on magnetoimpedance effect in Fe-rich amorphous microwires at high frequencies

Energy Technology Data Exchange (ETDEWEB)

Garcia, C. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, 20018 San Sebastian (Spain)]. E-mail: wubgagac@sc.ehu.es; Chizhik, A. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, 20018 San Sebastian (Spain); Zhukov, A. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, 20018 San Sebastian (Spain); Zhukova, V. [TAMAG Iberica S. L. Parque Tecnologico de Miramon, Paseo Mikeletegi 56, 1a Planta, 20009 San Sebastian (Spain); Gonzalez, J. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, 20018 San Sebastian (Spain); Blanco, J.M. [Dpto. Fisica Aplicada I. EUPDS, UPV/EHU, Plaza Europa 1, 20018 San Sebastian (Spain); Panina, L.V. [University of Plymouth, Drakes Circus, Plymouth (United Kingdom)

2007-09-15

In this work, we study the magnetoimpedance response under tensile and torsional stress of Fe{sub 76}B{sub 13}Si{sub 11} glass-coated amorphous microwires (with the metallic nucleus diameter of 17 {mu}m) prepared by Taylor-Ulitovski method. The impedance was evaluated using a Network Analyser in the frequency range of 10-500 MHz. In order to induce a helical magnetic anisotropy that modifies the magnetic domain structure and the magnetic response of the sample, the torsion stresses have been applied. The effect of such torsion on giant magnetoimpedance (GMI) has been studied in a Fe-rich amorphous microwire as a function of the driving current frequency. Unusual behaviour of the GMI with torsion has been observed up to 500 MHz: at this frequency, the change from double-peak to single-peak behaviour has been observed. It could be ascribed to changes on domain structures and surface anisotropy induced by applied torsion. For this frequency range, an abrupt decrease of the impedance with torsion has been observed. We have also studied the tensile-induced changes of GMI effect in a Fe-rich amorphous microwire. The GMI effect increases with applied tensile stress and with the frequency of AC current. Observed dependences could be attributed to the change of the overall magnetic anisotropy under applied torsion.

Rigidity of monodromies for Appell's hypergeometric functions

Directory of Open Access Journals (Sweden)

Yoshishige Haraoka

2015-01-01

Full Text Available For monodromy representations of holonomic systems, the rigidity can be defined. We examine the rigidity of the monodromy representations for Appell's hypergeometric functions, and get the representations explicitly. The results show how the topology of the singular locus and the spectral types of the local monodromies work for the study of the rigidity.

Amorphous iron (II) carbonate

DEFF Research Database (Denmark)

Sel, Ozlem; Radha, A.V.; Dideriksen, Knud

2012-01-01

Abstract The synthesis, characterization and crystallization energetics of amorphous iron (II) carbonate (AFC) are reported. AFC may form as a precursor for siderite (FeCO3). The enthalpy of crystallization (DHcrys) of AFC is similar to that of amorphous magnesium carbonate (AMC) and more...

Amorphization of ceramics by ion beams

International Nuclear Information System (INIS)

McHargue, C.J.; Farlow, G.C.; White, C.W.; Williams, J.M.; Appleton, B.R.; Naramoto, H.

1984-01-01

The influence of the implantation parameters fluence, substrate temperature, and chemical species on the formation of amorphous phases in Al 2 O 3 and α-SiC was studied. At 300 0 K, fluences in excess of 10 17 ions.cm -2 were generally required to amorphize Al 2 O 3 ; however, implantation of zirconium formed the amorphous phase at a fluence of 4 x 10 16 Zr.cm -2 . At 77 0 K, the threshold fluence was lowered to about 2 x 10 15 Cr.cm -2 . Single crystals of α-SiC were amorphized at 300 0 K by a fluence of 2 x 10 14 Cr.cm -2 or 1 x 10 15 N.cm -2 . Implantation at 1023 0 K did not produce the amorphous phase in SiC. The micro-indentation hardness of the amorphous material was about 60% of that of the crystalline counterpart

Amorphization within the tablet

DEFF Research Database (Denmark)

Doreth, Maria; Hussein, Murtadha Abdul; Priemel, Petra A.

2017-01-01

, the feasibility of microwave irradiation to prepare amorphous solid dispersions (glass solutions) in situ was investigated. Indomethacin (IND) and polyvinylpyrrolidone K12 (PVP) were tableted at a 1:2 (w/w) ratio. In order to study the influence of moisture content and energy input on the degree of amorphization......, tablet formulations were stored at different relative humidity (32, 43 and 54% RH) and subsequently microwaved using nine different power-time combinations up to a maximum energy input of 90 kJ. XRPD results showed that up to 80% (w/w) of IND could be amorphized within the tablet. mDSC measurements...

Crystalline to amorphous transformation in silicon

International Nuclear Information System (INIS)

Cheruvu, S.M.

1982-09-01

In the present investigation, an attempt was made to understand the fundamental mechanism of crystalline-to-amorphous transformation in arsenic implanted silicon using high resolution electron microscopy. A comparison of the gradual disappearance of simulated lattice fringes with increasing Frenkel pair concentration with the experimental observation of sharp interfaces between crystalline and amorphous regions was carried out leading to the conclusion that when the defect concentration reaches a critical value, the crystal does relax to an amorphous state. Optical diffraction experiments using atomic models also supported this hypothesis. Both crystalline and amorphous zones were found to co-exist with sharp interfaces at the atomic level. Growth of the amorphous fraction depends on the temperature, dose rate and the mass of the implanted ion. Preliminary results of high energy electron irradiation experiments at 1.2 MeV also suggested that clustering of point defects occurs near room temperature. An observation in a high resolution image of a small amorphous zone centered at the core of a dislocation is presented as evidence that the nucleation of an amorphous phase is heterogeneous in nature involving clustering or segregation of point defects near existing defects

Amorphous titanium-oxide supercapacitors

Science.gov (United States)

Fukuhara, Mikio; Kuroda, Tomoyuki; Hasegawa, Fumihiko

2016-10-01

The electric capacitance of an amorphous TiO2-x surface increases proportionally to the negative sixth power of the convex diameter d. This occurs because of the van der Waals attraction on the amorphous surface of up to 7 mF/cm2, accompanied by extreme enhanced electron trapping resulting from both the quantum-size effect and an offset effect from positive charges at oxygen-vacancy sites. Here we show that a supercapacitor, constructed with a distributed constant-equipment circuit of large resistance and small capacitance on the amorphous TiO2-x surface, illuminated a red LED for 37 ms after it was charged with 1 mA at 10 V. The fabricated device showed no dielectric breakdown up to 1,100 V. Based on this approach, further advances in the development of amorphous titanium-dioxide supercapacitors might be attained by integrating oxide ribbons with a micro-electro mechanical system.

Amorphous silicon based particle detectors

OpenAIRE

Wyrsch, N.; Franco, A.; Riesen, Y.; Despeisse, M.; Dunand, S.; Powolny, F.; Jarron, P.; Ballif, C.

2012-01-01

Radiation hard monolithic particle sensors can be fabricated by a vertical integration of amorphous silicon particle sensors on top of CMOS readout chip. Two types of such particle sensors are presented here using either thick diodes or microchannel plates. The first type based on amorphous silicon diodes exhibits high spatial resolution due to the short lateral carrier collection. Combination of an amorphous silicon thick diode with microstrip detector geometries permits to achieve micromete...

From Wage Rigidities to Labour Market Rigidities: A Turning-Point in Explaining Equilibrium Unemployment?

OpenAIRE

Marco Guerrazzi; Nicola Meccheri

2009-01-01

This paper offers a critical discussion of the concept of labour market rigidity relevant to explaining unemployment. Starting from Keynes’s own view, we discuss how the concept of labour market flexibility has changed over time, involving nominal or real wage flexibility, contract flexibility or labour market institution flexibility. We also provide a critical assessment of the factors that lead the search framework highlighting labour market rigidities (frictions) to challenge the more wide...

Origins of amorphous interstellar grains

International Nuclear Information System (INIS)

Hasegawa, H.

1984-01-01

The existence of amorphous interstellar grains has been suggested from infrared observations. Some carbon stars show the far infrared emission with a lambda -1 wavelength dependence. Far infrared emission supposed to be due to silicate grains often show the lambda -1 wavelength dependence. Mid infrared spectra around 10 μm have broad structure. These may be due to the amorphous silicate grains. The condition that the condensed grains from the cosmic gas are amorphous is discussed. (author)

Identifying Floppy and Rigid Regions in Proteins

Science.gov (United States)

Jacobs, D. J.; Thorpe, M. F.; Kuhn, L. A.

1998-03-01

In proteins it is possible to separate hard covalent forces involving bond lengths and bond angles from other weak forces. We model the microstructure of the protein as a generic bar-joint truss framework, where the hard covalent forces and strong hydrogen bonds are regarded as rigid bar constraints. We study the mechanical stability of proteins using FIRST (Floppy Inclusions and Rigid Substructure Topography) based on a recently developed combinatorial constraint counting algorithm (the 3D Pebble Game), which is a generalization of the 2D pebble game (D. J. Jacobs and M. F. Thorpe, ``Generic Rigidity: The Pebble Game'', Phys. Rev. Lett.) 75, 4051-4054 (1995) for the special class of bond-bending networks (D. J. Jacobs, "Generic Rigidity in Three Dimensional Bond-bending Networks", Preprint Aug (1997)). This approach is useful in identifying rigid motifs and flexible linkages in proteins, and thereby determines the essential degrees of freedom. We will show some preliminary results from the FIRST analysis on the myohemerythrin and lyozyme proteins.

Recent advances in co-amorphous drug formulations

DEFF Research Database (Denmark)

Dengale, Swapnil Jayant; Grohganz, Holger; Rades, Thomas

2016-01-01

with other amorphous stabilization techniques. Because of this, several research groups started to investigate the co-amorphous formulation approach, resulting in an increasing amount of scientific publications over the last few years. This study provides an overview of the co-amorphous field and its recent......Co-amorphous drug delivery systems have recently gained considerable interest in the pharmaceutical field because of their potential to improve oral bioavailability of poorly water-soluble drugs through drug dissolution enhancement as a result of the amorphous nature of the material. A co...... findings. In particular, we investigate co-amorphous formulations from the viewpoint of solid dispersions, describe their formation and mechanism of stabilization, study their impact on dissolution and in vivo performance and briefly outline the future potentials....

Colors and the evolution of amorphous galaxies

International Nuclear Information System (INIS)

Gallagher, J.S. III; Hunter, D.A.

1987-01-01

UBVRI and H-alpha photometric observations are presented for 16 amorphous galaxies and a comparison sample of Magellanic irregular (Im) and Sc spiral galaxies. These data are analyzed in terms of star-formation rates and histories in amorphous galaxies. Amorphous galaxies have mean global colors and star-formation rates per unit area that are similar to those in giant Im systems, despite differences in spatial distributions of star-forming centers in these two galactic structural classes. Amorphous galaxies differ from giant Im systems in having somewhat wider scatter in relationships between B - V and U - B colors, and between U - B and L(H-alpha)/L(B). This scatter is interpreted as resulting from rapid variations in star-formation rates during the recent past, which could be a natural consequence of the concentration of star-forming activity into centrally located, supergiant young stellar complexes in many amorphous galaxies. While the unusual spatial distribution and intensity of star formation in some amorphous galaxies is due to interactions with other galaxies, several amorphous galaxies are relatively isolated and thus the processes must be internal. The ultimate evolutionary fate of rapidly evolving amorphous galaxies remains unknown. 77 references

The BID Domain of Type IV Secretion Substrates Forms a Conserved Four-Helix Bundle Topped with a Hook.

Science.gov (United States)

Stanger, Frédéric V; de Beer, Tjaart A P; Dranow, David M; Schirmer, Tilman; Phan, Isabelle; Dehio, Christoph

2017-01-03

The BID (Bep intracellular delivery) domain functions as secretion signal in a subfamily of protein substrates of bacterial type IV secretion (T4S) systems. It mediates transfer of (1) relaxases and the attached DNA during bacterial conjugation, and (2) numerous Bartonella effector proteins (Beps) during protein transfer into host cells infected by pathogenic Bartonella species. Furthermore, BID domains of Beps have often evolved secondary effector functions within host cells. Here, we provide crystal structures for three representative BID domains and describe a novel conserved fold characterized by a compact, antiparallel four-helix bundle topped with a hook. The conserved hydrophobic core provides a rigid scaffold to a surface that, despite a few conserved exposed residues and similarities in charge distribution, displays significant variability. We propose that the genuine function of BID domains as T4S signal may primarily depend on their rigid structure, while the plasticity of their surface may facilitate adaptation to secondary effector functions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Soft soils reinforced by rigid vertical inclusions

Directory of Open Access Journals (Sweden)

Iulia-Victoria NEAGOE

2013-12-01

Full Text Available Reinforcement of soft soils by rigid vertical inclusions is an increasingly used technique over the last few years. The system consists of rigid or semi-rigid vertical inclusions and a granular platform for the loads transfer from the structure to the inclusions. This technique aims to reduce the differential settlements both at ground level as below the structure. Reinforcement by rigid inclusions is mainly used for foundation works for large commercial and industrial platforms, storage tanks, wastewater treatment plants, wind farms, bridges, roads, railway embankments. The subject is one of interest as it proves the recently concerns at international level in research and design; however, most studies deal more with the static behavior and less with the dynamic one.

Micromagnetic analysis of current-induced domain wall motion in a bilayer nanowire with synthetic antiferromagnetic coupling

Energy Technology Data Exchange (ETDEWEB)

Komine, Takashi, E-mail: komine@mx.ibaraki.ac.jp; Aono, Tomosuke [Faculty of Engineering, Ibaraki University 4-12-1, Nakanarusawa, Hitachi, Ibaraki, 316-8511 (Japan)

2016-05-15

We demonstrate current-induced domain wall motion in bilayer nanowire with synthetic antiferromagnetic (SAF) coupling by modeling two body problems for motion equations of domain wall. The influence of interlayer exchange coupling and magnetostatic interactions on current-induced domain wall motion in SAF nanowires was also investigated. By assuming the rigid wall model for translational motion, the interlayer exchange coupling and the magnetostatic interaction between walls and domains in SAF nanowires enhances domain wall speed without any spin-orbit-torque. The enhancement of domain wall speed was discussed by energy distribution as a function of wall angle configuration in bilayer nanowires.

The sandwich domain structure in a Fe-based amorphous ribbon with uniaxial magnetic anisotropy

International Nuclear Information System (INIS)

Zhmetko, D.N.; Matsura, A.V.; Troschenkov, Y.N.; Seidametov, S.V.

2011-01-01

The formation and motion of two domain walls parallel to the ribbon surface are discovered during its dynamic magnetic reversal. The domain walls form near by the middle plane of a ribbon and move to its opposite main surfaces with different velocities.

A thermodynamic approach to model the caloric properties of semicrystalline polymers

Science.gov (United States)

Lion, Alexander; Johlitz, Michael

2016-05-01

It is well known that the crystallisation and melting behaviour of semicrystalline polymers depends in a pronounced manner on the temperature history. If the polymer is in the liquid state above the melting point, and the temperature is reduced to a level below the glass transition, the final degree of crystallinity, the amount of the rigid amorphous phase and the configurational state of the mobile amorphous phase strongly depend on the cooling rate. If the temperature is increased afterwards, the extents of cold crystallisation and melting are functions of the heating rate. Since crystalline and amorphous phases exhibit different densities, the specific volume depends also on the temperature history. In this article, a thermodynamically based phenomenological approach is developed which allows for the constitutive representation of these phenomena in the time domain. The degree of crystallinity and the configuration of the amorphous phase are represented by two internal state variables whose evolution equations are formulated under consideration of the second law of thermodynamics. The model for the specific Gibbs free energy takes the chemical potentials of the different phases and the mixture entropy into account. For simplification, it is assumed that the amount of the rigid amorphous phase is proportional to the degree of crystallinity. An essential outcome of the model is an equation in closed form for the equilibrium degree of crystallinity in dependence on pressure and temperature. Numerical simulations demonstrate that the process dependences of crystallisation and melting under consideration of the glass transition are represented.

Structure, thermodynamics, and crystallization of amorphous hafnia

International Nuclear Information System (INIS)

Luo, Xuhui; Demkov, Alexander A.

2015-01-01

We investigate theoretically amorphous hafnia using the first principles melt and quench method. We identify two types of amorphous structures of hafnia. Type I and type II are related to tetragonal and monoclinic hafnia, respectively. We find type II structure to show stronger disorder than type I. Using the phonon density of states, we calculate the specific heat capacity for type II amorphous hafnia. Using the nudged elastic band method, we show that the averaged transition barrier between the type II amorphous hafnia and monoclinic phase is approximately 0.09 eV/HfO 2 . The crystallization temperature is estimated to be 421 K. The calculations suggest an explanation for the low thermal stability of amorphous hafnia

Amorphous-crystalline transition in thermoelectric NbO2

International Nuclear Information System (INIS)

Music, Denis; Chen, Yen-Ting; Bliem, Pascal; Geyer, Richard W

2015-01-01

Density functional theory was employed to design enhanced amorphous NbO 2 thermoelectrics. The covalent-ionic nature of Nb–O bonding is identical in amorphous NbO 2 and its crystalline counterpart. However, the Anderson localisation occurs in amorphous NbO 2 , which may affect the transport properties. We calculate a multifold increase in the absolute Seebeck coefficient for the amorphous state. These predictions were critically appraised by measuring the Seebeck coefficient of sputtered amorphous and crystalline NbO 2 thin films with the identical short-range order. The first-order phase transition occurs at approximately 550 °C, but amorphous NbO 2 possesses enhanced transport properties at all temperatures. Amorphous NbO 2 , reaching  −173 μV K −1 , exhibits up to a 29% larger absolute Seebeck coefficient value, thereby validating the predictions. (paper)

Hydrogels from Amorphous Calcium Carbonate and Polyacrylic Acid: Bio-Inspired Materials for "Mineral Plastics".

Science.gov (United States)

Sun, Shengtong; Mao, Li-Bo; Lei, Zhouyue; Yu, Shu-Hong; Cölfen, Helmut

2016-09-19

Given increasing environmental issues due to the large usage of non-biodegradable plastics based on petroleum, new plastic materials, which are economic, environmentally friendly, and recyclable are in high demand. One feasible strategy is the bio-inspired synthesis of mineral-based hybrid materials. Herein we report a facile route for an amorphous CaCO3 (ACC)-based hydrogel consisting of very small ACC nanoparticles physically cross-linked by poly(acrylic acid). The hydrogel is shapeable, stretchable, and self-healable. Upon drying, the hydrogel forms free-standing, rigid, and transparent objects with remarkable mechanical performance. By swelling in water, the material can completely recover the initial hydrogel state. As a matrix, thermochromism can also be easily introduced. The present hybrid hydrogel may represent a new class of plastic materials, the "mineral plastics". © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural, dynamic, electronic, and vibrational properties of flexible, intermediate, and stressed rigid As-Se glasses and liquids from first principles molecular dynamics

International Nuclear Information System (INIS)

Bauchy, M.; Kachmar, A.; Micoulaut, M.

2014-01-01

The structural, vibrational, electronic, and dynamic properties of amorphous and liquid As x Se 1-x (0.10 rigidity within the network, while also providing a much more complex picture than the one derived from mean-field approaches of stiffness transitions

Model for amorphous aggregation processes

Science.gov (United States)

Stranks, Samuel D.; Ecroyd, Heath; van Sluyter, Steven; Waters, Elizabeth J.; Carver, John A.; von Smekal, Lorenz

2009-11-01

The amorphous aggregation of proteins is associated with many phenomena, ranging from the formation of protein wine haze to the development of cataract in the eye lens and the precipitation of recombinant proteins during their expression and purification. While much literature exists describing models for linear protein aggregation, such as amyloid fibril formation, there are few reports of models which address amorphous aggregation. Here, we propose a model to describe the amorphous aggregation of proteins which is also more widely applicable to other situations where a similar process occurs, such as in the formation of colloids and nanoclusters. As first applications of the model, we have tested it against experimental turbidimetry data of three proteins relevant to the wine industry and biochemistry, namely, thaumatin, a thaumatinlike protein, and α -lactalbumin. The model is very robust and describes amorphous experimental data to a high degree of accuracy. Details about the aggregation process, such as shape parameters of the aggregates and rate constants, can also be extracted.

Superplasticity of amorphous alloy

International Nuclear Information System (INIS)

Levin, Yu.B.; Likhachev, V.L.; Sen'kov, O.N.

1988-01-01

Results of mechanical tests of Co 57 Ni 10 Fe 5 Si 11 B 17 amorphous alloy are presented and the effect of crystallization, occurring during deformation process, on plastic low characteristics is investiagted. Superplasticity of amorphous tape is investigated. It is shown, that this effect occurs only when during deformation the crystallization takes place. Process model, based on the usage disclination concepts about glass nature, is suggested

Amorphous silicon ionizing particle detectors

Science.gov (United States)

Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

1988-01-01

Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

Emerging trends in the stabilization of amorphous drugs.

Science.gov (United States)

Laitinen, Riikka; Löbmann, Korbinian; Strachan, Clare J; Grohganz, Holger; Rades, Thomas

2013-08-30

The number of active pharmaceutical substances having high therapeutic potential but low water solubility is constantly increasing, making it difficult to formulate these compounds as oral dosage forms. The solubility and dissolution rate, and thus potentially the bioavailability, of these poorly water-soluble drugs can be increased by the formation of stabilized amorphous forms. Currently, formulation as solid polymer dispersions is the preferred method to enhance drug dissolution and to stabilize the amorphous form of a drug. The purpose of this review is to highlight emerging alternative methods to amorphous polymer dispersions for stabilizing the amorphous form of drugs. First, an overview of the properties and stabilization mechanisms of amorphous forms is provided. Subsequently, formulation approaches such as the preparation of co-amorphous small-molecule mixtures and the use of mesoporous silicon and silica-based carriers are presented as potential means to increase the stability of amorphous pharmaceuticals. Copyright © 2012 Elsevier B.V. All rights reserved.

Operating method of amorphous thin film semiconductor element

Energy Technology Data Exchange (ETDEWEB)

Mori, Koshiro; Ono, Masaharu; Hanabusa, Akira; Osawa, Michio; Arita, Takashi

1988-05-31

The existing technologies concerning amorphous thin film semiconductor elements are the technologies concerning the formation of either a thin film transistor or an amorphous Si solar cell on a substrate. In order to drive a thin film transistor for electronic equipment control by the output power of an amorphous Si solar cell, it has been obliged to drive the transistor weth an amorphous solar cell which was formed on a substrate different from that for the transistor. Accordingly, the space for the amorphous solar cell, which was formed on the different substrate, was additionally needed on the substrate for the thin film transistor. In order to solve the above problem, this invention proposes an operating method of an amorphous thin film semiconductor element that after forming an amorphous Si solar cell through lamination on the insulation coating film which covers the thin film transistor formed on the substrate, the thin film transistor is driven by the output power of this solar cell. The invention eliminates the above superfluous space and reduces the size of the amorphous thin film semiconductor element including the electric source. (3 figs)

Crystallization inhibitors for amorphous oxides

International Nuclear Information System (INIS)

Reznitskij, L.A.; Filippova, S.E.

1993-01-01

Data for the last 10 years, in which experimental results of studying the temperature stabilization of x-ray amorphous oxides (including R 3 Fe 5 O 12 R-rare earths, ZrO 2 , In 2 O 3 , Sc 2 O 3 ) and their solid solution are presented, are generalized. Processes of amorphous oxide crystallization with the production of simple oxides, solid solutions and chemical compounds with different polyhedral structure, are investigated. Energy and crystallochemical criteria for selecting the doping inhibitor-components stabilizing the amorphous state are ascertained, temperatures and enthalpies of amorpous oxide crystallization are determined, examination of certain provisions of iso,orphous miscibility theory is conducted

Thermostability in rubredoxin and its relationship to mechanical rigidity

Science.gov (United States)

Rader, A. J.

2010-03-01

The source of increased stability in proteins from organisms that thrive in extreme thermal environments is not well understood. Previous experimental and theoretical studies have suggested many different features possibly responsible for such thermostability. Many of these thermostabilizing mechanisms can be accounted for in terms of structural rigidity. Thus a plausible hypothesis accounting for this remarkable stability in thermophilic enzymes states that these enzymes have enhanced conformational rigidity at temperatures below their native, functioning temperature. Experimental evidence exists to both support and contradict this supposition. We computationally investigate the relationship between thermostability and rigidity using rubredoxin as a case study. The mechanical rigidity is calculated using atomic models of homologous rubredoxin structures from the hyperthermophile Pyrococcus furiosus and mesophile Clostridium pasteurianum using the FIRST software. A global increase in structural rigidity (equivalently a decrease in flexibility) corresponds to an increase in thermostability. Locally, rigidity differences (between mesophilic and thermophilic structures) agree with differences in protection factors.

Thermostability in rubredoxin and its relationship to mechanical rigidity

International Nuclear Information System (INIS)

Rader, A J

2010-01-01

The source of increased stability in proteins from organisms that thrive in extreme thermal environments is not well understood. Previous experimental and theoretical studies have suggested many different features possibly responsible for such thermostability. Many of these thermostabilizing mechanisms can be accounted for in terms of structural rigidity. Thus a plausible hypothesis accounting for this remarkable stability in thermophilic enzymes states that these enzymes have enhanced conformational rigidity at temperatures below their native, functioning temperature. Experimental evidence exists to both support and contradict this supposition. We computationally investigate the relationship between thermostability and rigidity using rubredoxin as a case study. The mechanical rigidity is calculated using atomic models of homologous rubredoxin structures from the hyperthermophile Pyrococcus furiosus and mesophile Clostridium pasteurianum using the FIRST software. A global increase in structural rigidity (equivalently a decrease in flexibility) corresponds to an increase in thermostability. Locally, rigidity differences (between mesophilic and thermophilic structures) agree with differences in protection factors

49 CFR 587.18 - Dimensions of fixed rigid barrier.

Science.gov (United States)

2010-10-01

... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) DEFORMABLE BARRIERS Offset Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not... 49 Transportation 7 2010-10-01 2010-10-01 false Dimensions of fixed rigid barrier. 587.18 Section...

RIGIDITY, SENSITIVITY AND QUALITY OF ATTACHMENT - THE ROLE OF MATERNAL RIGIDITY IN THE EARLY SOCIOEMOTIONAL DEVELOPMENT OF PREMATURE-INFANTS

NARCIS (Netherlands)

BUTCHER, PR; KALVERBOER, A; MINDERAA, RB; VANDOORMAAL, EF; TENWOLDE, Y

1993-01-01

The associations between a mother's rigidity, her sensitivity in early (3 month) interaction and the quality of her premature infant's attachment at 13 months were investigated. Rigidity as a personality characteristic was not found to be significantly associated with sensitivity or quality of

Ab initio simulation of amorphous silicon

International Nuclear Information System (INIS)

Cooper, N.C.; McKenzie, D.R.; Goringe, C.M.

1999-01-01

Full text: A first-principles Car-Parrinello molecular dynamics simulation of amorphous silicon is presented. Density Functional Theory is used to describe the forces between the atoms in a 64 atom supercell which is periodically repeated throughout space in order to generate an infinite network of atoms (a good approximation to a real solid). A quench from the liquid phase is used to achieve a quenched amorphous structure, which is subjected to an annealing cycle to improve its stability. The final, annealed network is in better agreement with experiment than any previous simulation of amorphous silicon. Significantly, the predicted average first-coordination numbers of 3.56 and 3.84 for the quenched and annealed structures from this simulation agree very closely with the experimental values of 3.55 and 3.90 respectively, whereas all previous simulations yielded first coordination numbers greater than 4. This improved agreement in coordination numbers is important because it supports the experimental finding that dangling bonds (which are associated with under-coordinated atoms) are more prevalent than floating bonds (the strained, longer bond of a five coordinate atom) in pure amorphous silicon. Finally, the effect of adding hydrogen to amorphous silicon was investigated by specifically placing hydrogen atoms at the likely defect sites. After a structural relaxation to optimise the positions of these hydrogen atoms, the localised electronic states associated with these defects are absent. Thus hydrogen is responsible for removing these defect states (which are able to trap carriers) from the edge of the band gap of the amorphous silicon. These results confirm the widely held ideas about the effect of hydrogen in producing remarkable improvements in the electronic properties of amorphous silicon

Neutron irradiation induced amorphization of silicon carbide

International Nuclear Information System (INIS)

Snead, L.L.; Hay, J.C.

1998-01-01

This paper provides the first known observation of silicon carbide fully amorphized under neutron irradiation. Both high purity single crystal hcp and high purity, highly faulted (cubic) chemically vapor deposited (CVD) SiC were irradiated at approximately 60 C to a total fast neutron fluence of 2.6 x 10 25 n/m 2 . Amorphization was seen in both materials, as evidenced by TEM, electron diffraction, and x-ray diffraction techniques. Physical properties for the amorphized single crystal material are reported including large changes in density (-10.8%), elastic modulus as measured using a nanoindentation technique (-45%), hardness as measured by nanoindentation (-45%), and standard Vickers hardness (-24%). Similar property changes are observed for the critical temperature for amorphization at this neutron dose and flux, above which amorphization is not possible, is estimated to be greater than 130 C

Salt Fog Testing Iron-Based Amorphous Alloys

International Nuclear Information System (INIS)

Rebak, Raul B.; Aprigliano, Louis F.; Day, S. Daniel; Farmer, Joseph C.

2007-01-01

Iron-based amorphous alloys are hard and highly corrosion resistant, which make them desirable for salt water and other applications. These alloys can be produced as powder and can be deposited as coatings on any surface that needs to be protected from the environment. It was of interest to examine the behavior of these amorphous alloys in the standard salt-fog testing ASTM B 117. Three different amorphous coating compositions were deposited on 316L SS coupons and exposed for many cycles of the salt fog test. Other common engineering alloys such as 1018 carbon steel, 316L SS and Hastelloy C-22 were also tested together with the amorphous coatings. Results show that amorphous coatings are resistant to rusting in salt fog. Partial devitrification may be responsible for isolated rust spots in one of the coatings. (authors)

Thermal relaxation of magnetic clusters in amorphous Hf57Fe43 alloy

International Nuclear Information System (INIS)

Pajic, Damir; Zadro, Kreso; Ristic, Ramir; Zivkovic, Ivica; Skoko, Zeljko; Babic, Emil

2007-01-01

The magnetization processes in binary magnetic/non-magnetic amorphous alloy Hf 57 Fe 43 are investigated by the detailed measurement of magnetic hysteresis loops, temperature dependence of magnetization, relaxation of magnetization and magnetic ac susceptibility, including a nonlinear term. Blocking of magnetic moments at lower temperatures is accompanied by the slow relaxation of magnetization and magnetic hysteresis loops. All of the observed properties are explained by the superparamagnetic behaviour of the single domain magnetic clusters inside the non-magnetic host, their blocking by the anisotropy barriers and thermal fluctuation over the barriers accompanied by relaxation of magnetization. From magnetic viscosity analysis based on thermal relaxation over the anisotropy barriers it is found that magnetic clusters occupy the characteristic volume from 25 up to 200 nm 3 . The validity of the superparamagnetic model of Hf 57 Fe 43 is based on the concentration of iron in the Hf 100-x Fe x system that is just below the threshold for long range magnetic ordering. This work also throws more light on the magnetic behaviour of other amorphous alloys

Soil-structure interaction analysis of NPP containments: substructure and frequency domain methods

International Nuclear Information System (INIS)

Venancio-Filho, F.; Almeida, M.C.F.; Ferreira, W.G.; De Barros, F.C.P.

1997-01-01

Substructure and frequency domain methods for soil-structure interaction are addressed in this paper. After a brief description of mathematical models for the soil and of excitation, the equations for dynamic soil-structure interaction are developed for a rigid surface foundation and for an embedded foundation. The equations for the frequency domain analysis of MDOF systems are provided. An example of soil-structure interaction analysis with frequency-dependent soil properties is given and examples of identification of foundation impedance functions and soil properties are presented. (orig.)

Effects of the amorphization on hysteresis loops of the amorphous spin-1/2 Ising system

International Nuclear Information System (INIS)

Essaoudi, I.; Ainane, A.; Saber, M.; Miguel, J.J. de

2009-01-01

We examine the effects of the amorphization on the hysteresis loops of the amorphous spin-1/2 Ising system using the effective field theory within a probability distribution technique that accounts for the self-spin correlation functions. The magnetization, the transverse and longitudinal susceptibilities, and pyromagnetic coefficient are also studied in detail

Low-temperature crystallization of amorphous silicon and amorphous germanium by soft X-ray irradiation

Energy Technology Data Exchange (ETDEWEB)

Heya, Akira, E-mail: heya@eng.u-hyogo.ac.jp [Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671–2280 (Japan); Kanda, Kazuhiro [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Toko, Kaoru; Sadoh, Taizoh [Department of Electronics, Kyushu University, 744 Nishi-ku, Motooka, Fukuoka 819–0395 (Japan); Amano, Sho [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Matsuo, Naoto [Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671–2280 (Japan); Miyamoto, Shuji [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Miyao, Masanobu [Department of Electronics, Kyushu University, 744 Nishi-ku, Motooka, Fukuoka 819–0395 (Japan); Mochizuki, Takayasu [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan)

2013-05-01

The low-temperature-crystallization effects of soft X-ray irradiation on the structural properties of amorphous Si and amorphous Ge films were investigated. From the differences in crystallization between Si and Ge, it was found that the effects of soft X-ray irradiation on the crystallization strongly depended on the energy band gap and energy level. The crystallization temperatures of the amorphous Si and amorphous Ge films decreased from 953 K to 853 K and 773 K to 663 K, respectively. The decrease in crystallization temperature was also related to atoms transitioning into a quasi-nucleic phase in the films. The ratio of electron excitation and migration effects to thermal effects was controlled using the storage-ring current (photon flux density). Therefore, we believe that low-temperature crystallization can be realized by controlling atomic migration through electron excitation. - Highlights: • This work investigates the crystallization mechanism for soft X-ray irradiation. • The soft X-ray crystallization depended on the energy band gap and energy level. • The decrease in the crystallization temperature for Si and Ge films was 100 K. • This decrement was related to atoms transitioning into a quasi-nucleic phase.

Cracking of open traffic rigid pavement

Directory of Open Access Journals (Sweden)

Niken Chatarina

2017-01-01

Full Text Available The research is done by observing the growth of real structure cracking in Natar, Lampung, Indonesia compared to C. Niken’s et al research and literature study. The rigid pavement was done with open traffic system. There are two main crack types on Natar rigid pavement: cracks cross the road, and cracks spreads on rigid pavement surface. The observation of cracks was analyzed by analyzing material, casting, curing, loading and shrinkage mechanism. The relationship between these analysis and shrinkage mechanism was studied in concrete micro structure. Open traffic make hydration process occur under vibration; therefore, fresh concrete was compressed and tensioned alternately since beginning. High temperature together with compression, cement dissociation, the growth of Ca2+ at very early age leads abnormal swelling. No prevention from outside water movement leads hydration process occur with limited water which caused spreads fine cracks. Limited water improves shrinkage and plastic phase becomes shorter; therefore, rigid pavement can’t accommodate the abnormal swelling and shrinking alternately and creates the spread of cracks. Discontinuing casting the concrete makes both mix under different condition, the first is shrink and the second is swell and creates weak line on the border; so, the cracks appear as cracks across the road.

Magnetomechanical coupling in thermal amorphous solids

Science.gov (United States)

Hentschel, H. George E.; Ilyin, Valery; Mondal, Chandana; Procaccia, Itamar

2018-05-01

Standard approaches to magnetomechanical interactions in thermal magnetic crystalline solids involve Landau functionals in which the lattice anisotropy and the resulting magnetization easy axes are taken explicitly into account. In glassy systems one needs to develop a theory in which the amorphous structure precludes the existence of an easy axis, and in which the constituent particles are free to respond to their local amorphous surroundings and the resulting forces. We present a theory of all the mixed responses of an amorphous solid to mechanical strains and magnetic fields. Atomistic models are proposed in which we test the predictions of magnetostriction for both bulk and nanofilm amorphous samples in the paramagnetic phase. The application to nanofilms with emergent self-affine free interfaces requires a careful definition of the film "width" and its change due to the magnetostriction effect.

Reversible Rigidity Control Using Low Melting Temperature Alloys

Science.gov (United States)

Shan, Wanliang; Lu, Tong; Majidi, Carmel

2013-03-01

Inspired by nature, materials able to achieve rapid rigidity changes have important applications for human body protection in military and many other areas. This talk presents the fabrication and design of soft-matter technologies that exhibit rapid reversible rigidity control. Fabricated with a masked deposition technique, the soft-matter composite contains liquid-phase and phase-changing metal alloys embedded in a soft and highly stretchable elastomer. The composite material can reversibly change its rigidity by three orders of magnitude and sustain large deformation.

Multiple-target method for sputtering amorphous films for bubble-domain devices

International Nuclear Information System (INIS)

Burilla, C.T.; Bekebrede, W.R.; Smith, A.B.

1976-01-01

Previously, sputtered amorphous metal alloys for bubble applications have ordinarily been prepared by standard sputtering techniques using a single target electrode. The deposition of these alloys is reported using a multiple target rf technique in which a separate target is used for each element contained in the alloy. One of the main advantages of this multiple-target approach is that the film composition can be easily changed by simply varying the voltages applied to the elemental targets. In the apparatus, the centers of the targets are positioned on a 15 cm-radius circle. The platform holding the film substrate is on a 15 cm-long arm which can rotate about the center, thus bringing the sample successively under each target. The platform rotation rate is adjustable from 0 to 190 rpm. That this latter speed is sufficient to homogenize the alloys produced is demonstrated by measurements made of the uniaxial anisotropy constant in Gd 0 . 12 Co 0 . 59 Cu 0 . 29 films. The anisotropy is 6.0 x 10 5 ergs/cm 3 and independent of rotation rate above approximately 25 rpm, but it drops rapidly for slower rotation rates, reaching 1.8 x 10 5 ergs/cm 3 for 7 rpm. The film quality is equal to that of films made by conventional methods. Coercivities of a few oersteds in samples with stripe widths of 1 to 2 μm and magnetizations of 800 to 2800 G were observed

Determination of Weight Suspension Rigidity in the Transport-Erector Aggregates

Directory of Open Access Journals (Sweden)

V. A. Zverev

2016-01-01

Full Text Available The aim is to determine weight suspension rigidity in aggregates designed to perform technological transport-erector operations at the miscellaneous launch complexes.We consider the weight suspension comprising the following distinctive structural components: the executive weight-lowering mechanism, polyspast mechanism, rope, traverse, and rods. A created structural dynamic model of suspension allowed us to define weight suspension rigidity. Within the framework of design analysis of a dynamic model we determined the rigidity of its structural units, i.e. traverse, rope, and polyspast.Known analytical relationships were used to calculate the rope rigidity. To determine rigidity of polyspast and traverse have been created special models based on the finite element method. For each model deformation in the specific points under the test load have been defined. Data obtained were used to determine trigidity of traverses and polyspast, and also rigidity of suspension in total. The rigidity models of polispast mechanism and traverse have been developed and calculated using the software complex "Zenit-95".As the research results, the paper presents a dynamic model of the weight suspension of the transport-erector aggregate, the finite element models of the polispast mechanism and traverse, an algorithm for determining the weight suspension rigidity and relevant analytical relationships.Independent calculation of weight suspension rigidity enables us to simplify further dynamic calculation of the aggregate-weight system because it allows attaining a simpler model of the aggregate-weight system that uses the weight suspension model as an element of equivalent rigidity. Despite this simplification the model allows us to determine correctly weight movement parameters and overloads in the aggregate-weight system in the process of technical operations.

Amorphization kinetics of Zr3Fe under electron irradiation

International Nuclear Information System (INIS)

Motta, A.T.; Howe, L.M.; Okamoto, P.R.

1992-10-01

0.9 MeV electron irradiations were performed at 28--220 K in a high-voltage electron microscope (HVEM). By measuring onset, spread and final size of the amorphous region, factoring in the Guassian distribution of the beam, a kinetic description of the amorphization in terms of dose, dose rate and temperature was obtained. The critical temperature for amorphization by electron irradiation was found to be ∼220 K, compared to 570--625 K for 40 Ar ion irradiation. Also, the dose-to-amorphization increased exponentially with temperature. Results indicated that the rate of growth of the amorphous region under the electron beam decreased with increasing temperature and the does-to-amorphization decreased with increasing dose rate. The size of the amorphous region saturated after a region dose, the final size decreasing with increasing temperature, and it was argued that this is related to the existence of a critical dose rate, which increased with temperature, below which no amorphization occurred. The above observations can be understood in the framework of the kinetics of damage accumulation under irradiation

Influence of flock coating on bending rigidity of woven fabrics

Science.gov (United States)

Ozdemir, O.; Kesimci, M. O.

2017-10-01

This work presents the preliminary results of our efforts that focused on the effect of the flock coating on the bending rigidity of woven fabrics. For this objective, a laboratory scale flocking unit is designed and flocked samples of controlled flock density are produced. Bending rigidity of the samples with different flock densities are measured on both flocked and unflocked sides. It is shown that the bending rigidity depends on both flock density and whether the side to be measured is flocked or not. Adhesive layer thickness on the bending rigidity is shown to be dramatic. And at higher basis weights, flock density gets less effective on bending rigidity.

Fabrication of photonic amorphous diamonds for terahertz-wave applications

Energy Technology Data Exchange (ETDEWEB)

Komiyama, Yuichiro; Abe, Hiroyuki; Kamimura, Yasushi; Edagawa, Keiichi, E-mail: edagawa@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

2016-05-09

A recently proposed photonic bandgap material, named “photonic amorphous diamond” (PAD), was fabricated in a terahertz regime, and its terahertz-wave propagation properties were investigated. The PAD structure was fabricated from acrylic resin mixed with alumina powder, using laser lithographic, micro-additive manufacturing technique. After fabrication, the resulting structure was dewaxed and sintered. The formation of a photonic bandgap at around 0.45 THz was demonstrated by terahertz time-domain spectroscopy. Reflecting the disordered nature of the random network structure, diffusive terahertz-wave propagation was observed in the passbands; the scattering mean-free path decreased as the frequency approached the band edge. The mean-free paths evaluated at the band edges were close to the Ioffe-Regel threshold value for wave localization.

Amorphization kinetics of Zr3Fe under electron irradiation

International Nuclear Information System (INIS)

Motta, A.T.; Howe, L.M.; Okamoto, P.R.

1994-11-01

Previous investigations using 40 Ar ion bombardments have revealed that Zr 3 Fe, which has an orthorhombic crystal structure, undergoes an irradiation-induced transformation from the crystalline to the amorphous state. In the present investigation, 0.9 MeV electron irradiations were performed at 28 - 220 K in a high-voltage electron microscope (HVEM). By measuring the onset, spread and final size of the amorphous region, factoring in the Gaussian distribution of the beam, a kinetic description of the amorphization in terms of dose, dose rate and temperature was obtained. The critical temperature for amorphization by electron irradiation was found to be ∼ 220 K, compared with 570 - 625 K for 40 Ar ion irradiation. Also, the dose-to-amorphization increased exponentially with temperature. Results indicated that the rate of growth of the amorphous region under the electron beam decreased with increasing temperature and the dose-to-amorphization decreased with increasing dose rate. The size of the amorphous region saturated after a given dose, the final size decreasing with increasing temperature, and it is argued that this is related to the existence of a critical dose rate, which increases with temperature, and below which no amorphization occurs. (author). 26 refs., 6 figs

Structural, dynamic, electronic, and vibrational properties of flexible, intermediate, and stressed rigid As-Se glasses and liquids from first principles molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Bauchy, M. [Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-1593 (United States); Kachmar, A. [Laboratoire de Physique Théorique de la Matière Condensée, Université Pierre et Marie Curie, 4 Place Jussieu, F-75252 Paris Cedex 05 (France); Qatar Environment and Energy Research Institute, Qatar Foundation, P.O. Box 5825, Doha (Qatar); Micoulaut, M., E-mail: mmi@lptl.jussieu.fr [Laboratoire de Physique Théorique de la Matière Condensée, Université Pierre et Marie Curie, 4 Place Jussieu, F-75252 Paris Cedex 05 (France)

2014-11-21

The structural, vibrational, electronic, and dynamic properties of amorphous and liquid As{sub x}Se{sub 1-x} (0.10 rigidity within the network, while also providing a much more complex picture than the one derived from mean-field approaches of stiffness transitions.

Mechanical response of melt-spun amorphous filaments

International Nuclear Information System (INIS)

Leal, A A; Reifler, F A; Hufenus, R; Mohanty, G; Michler, J

2014-01-01

High-speed melt spinning of a cyclo-olefin polymer (COP) and a copolyamide (CoPA) have been performed. Differential scanning calorimetry curves of the resulting monofilaments show that they remain in an amorphous state even after hot drawing. Wide angle x-ray diffraction patterns of undrawn and drawn COP filaments show that although the material remains in an amorphous state, a degree of orientation is induced in the polymer after drawing. The amorphous filaments show an enhanced bending recovery with respect to different semi-crystalline monofilaments commercially available. However, single fiber axial compressive testing indicates that the amorphous filaments exhibit a compressive modulus value which is 50% lower than what is observed for a reference semi-crystalline PET filament. Analysis of the compressive strains applied by the bending recovery test indicates that while the maximum applied strains remain well within the region of elastic deformation of the amorphous materials, the threshold between elastic and plastic deformation is reached for the semi-crystalline materials. (paper)

Achievement report for fiscal 1991 on Sunshine Program-entrusted research and development. Research and development of amorphous silicon solar cells (Research on amorphous silicon interface); 1991 nendo amorphous silicon taiyo denchi no kenkyu kaihatsu seika hokokusho. Amorphous silicon no kaimen no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1992-03-01

The amorphous solar cell interface has been under study for the enhancement of efficiency and reliability in amorphous solar cells, and this is the compilation of the results achieved in fiscal 1991. In the effort to enhance delta-doped amorphous silicon solar cell efficiency, an amorphous Si solar cell is built using a ZnO film as the transparent conductive film. As the result, an a-Si solar cell with a conversion efficiency of 11.5% is obtained. In the research on the suppression of photodegradation in a-Si, from the viewpoint that a reduction in the amount of hydrogen contained excessively in the film will be effective in decelerating photodegradation, a photoexcited hydrogen radical treatment method is newly proposed, and basic studies are conducted on it. As the result, it is found that an a-Si film processed by a 20-second hydrogen treatment at a substrate temperature of 460 degrees C exhibits a lower photodegradation rate than an ordinary a-Si film. In the research on the deposition of amorphous Si film, a VHF frequency is used instead of 13.56MHz for plasma, and an amorphous Si film is deposited efficiently at a lower voltage at which ions cause less damage. (NEDO)

Amorphous titanium-oxide supercapacitors

OpenAIRE

Fukuhara, Mikio; Kuroda, Tomoyuki; Hasegawa, Fumihiko

2016-01-01

The electric capacitance of an amorphous TiO2-x surface increases proportionally to the negative sixth power of the convex diameter d. This occurs because of the van der Waals attraction on the amorphous surface of up to 7?mF/cm2, accompanied by extreme enhanced electron trapping resulting from both the quantum-size effect and an offset effect from positive charges at oxygen-vacancy sites. Here we show that a supercapacitor, constructed with a distributed constant-equipment circuit of large r...

Radiation tolerance of amorphous semiconductors

International Nuclear Information System (INIS)

Nicolaides, R.V.; DeFeo, S.; Doremus, L.W.

1976-01-01

In an attempt to determine the threshold radiation damage in amorphous semiconductors, radiation tests were performed on amorphous semiconductor thin film materials and on threshold and memory devices. The influence of flash x-rays and neutron radiation upon the switching voltages, on- and off-state characteristics, dielectric response, optical transmission, absorption band edge and photoconductivity were measured prior to, during and following irradiation. These extensive tests showed the high radiation tolerance of amorphous semiconductor materials. Electrical and optical properties, other than photoconductivity, have a neutron radiation tolerance threshold above 10 17 nvt in the steady state and 10 14 nvt in short (50 μsec to 16 msec) pulses. Photoconductivity increases by 1 1 / 2 orders of magnitude at the level of 10 14 nvt (short pulses of 50 μsec). Super flash x-rays up to 5000 rads (Si), 20 nsec, do not initiate switching in off-state samples which are voltage biased up to 90 percent of the threshold voltage. Both memory and threshold amorphous devices are capable of switching on and off during nuclear radiation transients at least as high as 2 x 10 14 nvt in 50 μsec pulses

Soft-matter composites with electrically tunable elastic rigidity

International Nuclear Information System (INIS)

Shan, Wanliang; Lu, Tong; Majidi, Carmel

2013-01-01

We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium–indium–tin (Galinstan ® ) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy. (paper)

Soft-matter composites with electrically tunable elastic rigidity

Science.gov (United States)

Shan, Wanliang; Lu, Tong; Majidi, Carmel

2013-08-01

We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium-indium-tin (Galinstan®) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy.

Interaction domains in high performance NdFeB thick films

Energy Technology Data Exchange (ETDEWEB)

Woodcock, Tom; Khlopkov, Kirill; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden, IMW, Dresden (Germany); Walther, Arno [Insitut Neel, CNRS-UJF, Grenoble (France); CEA Leti - MINATEC, Grenoble (France); Dempsey, Nora; Givord, Dominique [Insitut Neel, CNRS-UJF, Grenoble (France)

2009-07-01

Thick sputtered films (5-300 micron) of NdFeB have excellent hard magnetic properties which make them attractive for applications in micro-electro-mechanical systems (MEMS). A two step process consisting of triode sputtering and high temperature annealing produced films with energy densities approaching those of sintered NdFeB magnets. Magnetic force microscopy (MFM) using hard magnetic tips showed that the films deposited without substrate heating and at 300 C exhibited magnetic domains typical of low anisotropy materials. These films were amorphous in the as-deposited state. The film deposited at 500 C was crystalline and displaid hard magnetic properties. This was reflected in the magnetic microstructure which showed interaction domains typical of highly textured and high magnetic anisotropy materials with a grain size below or equal to the critical single-domain particle limit. With increasing substrate temperature, the domain patterns of the annealed films became coarser, indicating higher degrees of texture.

Rigid body motion in stereo 3D simulation

International Nuclear Information System (INIS)

Zabunov, Svetoslav

2010-01-01

This paper addresses the difficulties experienced by first-grade students studying rigid body motion at Sofia University. Most quantities describing the rigid body are in relations that the students find hard to visualize and understand. They also lose the notion of cause-result relations between vector quantities, such as the relation between torque and angular momentum. Consequently, the understanding of physical laws and conservation principles in free rigid body motion is hampered. This paper presents the capabilities of a 3D simulation, which aims to clarify these questions to the students, who are taught mechanics in the general physics course. The rigid body motion simulations may be observed at http://ialms.net/sim/, and are intended to complement traditional learning practices, not replace them, as the author shares the opinion that no simulation may fully resemble reality.

Photonic crystals, amorphous materials, and quasicrystals.

Science.gov (United States)

Edagawa, Keiichi

2014-06-01

Photonic crystals consist of artificial periodic structures of dielectrics, which have attracted much attention because of their wide range of potential applications in the field of optics. We may also fabricate artificial amorphous or quasicrystalline structures of dielectrics, i.e. photonic amorphous materials or photonic quasicrystals. So far, both theoretical and experimental studies have been conducted to reveal the characteristic features of their optical properties, as compared with those of conventional photonic crystals. In this article, we review these studies and discuss various aspects of photonic amorphous materials and photonic quasicrystals, including photonic band gap formation, light propagation properties, and characteristic photonic states.

Threshold irradiation dose for amorphization of silicon carbide

Energy Technology Data Exchange (ETDEWEB)

Snead, L.L.; Zinkle, S.J. [Oak Ridge National Lab., TN (United States)

1997-04-01

The amorphization of silicon carbide due to ion and electron irradiation is reviewed with emphasis on the temperature-dependent critical dose for amorphization. The effect of ion mass and energy on the threshold dose for amorphization is summarized, showing only a weak dependence near room temperature. Results are presented for 0.56 MeV silicon ions implanted into single crystal 6H-SiC as a function of temperature and ion dose. From this, the critical dose for amorphization is found as a function of temperature at depths well separated from the implanted ion region. Results are compared with published data generated using electrons and xenon ions as the irradiating species. High resolution TEM analysis is presented for the Si ion series showing the evolution of elongated amorphous islands oriented such that their major axis is parallel to the free surface. This suggests that surface of strain effects may be influencing the apparent amorphization threshold. Finally, a model for the temperature threshold for amorphization is described using the Si ion irradiation flux and the fitted interstitial migration energy which was found to be {approximately}0.56 eV. This model successfully explains the difference in the temperature-dependent amorphization behavior of SiC irradiated with 0.56 MeV silicon ions at 1 x 10{sup {minus}3} dpa/s and with fission neutrons irradiated at 1 x 10{sup {minus}6} dpa/s irradiated to 15 dpa in the temperature range of {approximately}340 {+-} 10K.

Threshold irradiation dose for amorphization of silicon carbide

International Nuclear Information System (INIS)

Snead, L.L.; Zinkle, S.J.

1997-01-01

The amorphization of silicon carbide due to ion and electron irradiation is reviewed with emphasis on the temperature-dependent critical dose for amorphization. The effect of ion mass and energy on the threshold dose for amorphization is summarized, showing only a weak dependence near room temperature. Results are presented for 0.56 MeV silicon ions implanted into single crystal 6H-SiC as a function of temperature and ion dose. From this, the critical dose for amorphization is found as a function of temperature at depths well separated from the implanted ion region. Results are compared with published data generated using electrons and xenon ions as the irradiating species. High resolution TEM analysis is presented for the Si ion series showing the evolution of elongated amorphous islands oriented such that their major axis is parallel to the free surface. This suggests that surface of strain effects may be influencing the apparent amorphization threshold. Finally, a model for the temperature threshold for amorphization is described using the Si ion irradiation flux and the fitted interstitial migration energy which was found to be ∼0.56 eV. This model successfully explains the difference in the temperature-dependent amorphization behavior of SiC irradiated with 0.56 MeV silicon ions at 1 x 10 -3 dpa/s and with fission neutrons irradiated at 1 x 10 -6 dpa/s irradiated to 15 dpa in the temperature range of ∼340 ± 10K

Threshold irradiation dose for amorphization of silicon carbide

International Nuclear Information System (INIS)

Snead, L.L.; Zinkle, S.J.

1997-01-01

The amorphization of silicon carbide due to ion and electron irradiation is reviewed with emphasis on the temperature-dependent critical dose for amorphization. The effect of ion mass and energy on the threshold dose for amorphization is summarized, showing only a weak dependence near room temperature. Results are presented for 0.56 MeV silicon ions implanted into single crystal 6H-SiC as a function of temperature and ion dose. From this, the critical dose for amorphization is found as a function of temperature at depths well separated from the implanted ion region. Results are compared with published data generated using electrons and xenon ions as the irradiating species. High resolution TEM analysis is presented for the Si ion series showing the evolution of elongated amorphous islands oriented such that their major axis is parallel to the free surface. This suggests that surface or strain effects may be influencing the apparent amorphization threshold. Finally, a model for the temperature threshold for amorphization is described using the Si ion irradiation flux and the fitted interstitial migration energy which was found to be ∼0.56eV. This model successfully explains the difference in the temperature dependent amorphization behavior of SiC irradiated with 0.56 MeV Si + at 1 x 10 -3 dpa/s and with fission neutrons irradiated at 1 x 10 -6 dpa/s irradiated to 15 dpa in the temperature range of ∼340±10K

FDTD simulation of amorphous silicon waveguides for microphotonics applications

Science.gov (United States)

Fantoni, A.; Lourenço, P.; Pinho, P.; Vieira, M.,

2017-05-01

In this work we correlate the dimension of the waveguide with small variations of the refractive index of the material used for the waveguide core. We calculate the effective modal refractive index for different dimensions of the waveguide and with slightly variation of the refractive index of the core material. These results are used as an input for a set of Finite Difference Time Domain simulation, directed to study the characteristics of amorphous silicon waveguides embedded in a SiO2 cladding. The study considers simple linear waveguides with rectangular section for studying the modal attenuation expected at different wavelengths. Transmission efficiency is determined analyzing the decay of the light power along the waveguides. As far as near infrared wavelengths are considered, a-Si:H shows a behavior highly dependent on the light wavelength and its extinction coefficient rapidly increases as operating frequency goes into visible spectrum range. The simulation results show that amorphous silicon can be considered a good candidate for waveguide material core whenever the waveguide length is as short as a few centimeters. The maximum transmission length is highly affected by the a-Si:H defect density, the mid-gap density of states and by the waveguide section area. The simulation results address a minimum requirement of 300nm×400nm waveguide section in order to keep attenuation below 1 dB cm-1.

Effects of hydrogenation on thermal conductivity of ultrananocrystalline diamond/amorphous carbon composite films prepared via coaxial arc plasma deposition

Science.gov (United States)

Takeichi, Satoshi; Nishiyama, Takashi; Tabara, Mitsuru; Kawawaki, Shuichi; Kohno, Masamichi; Takahashi, Koji; Yoshitake, Tsuyoshi

2018-06-01

Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite (UNCD/a-C:H) and UNCD/non-hydrogenated amorphous carbon (a-C) composite (UNCD/a-C) films were prepared via coaxial arc plasma deposition, and their thermal conductivity and interfacial conductance in grain boundaries were measured using a time-domain thermoreflectance method. The interfacial conductance was estimated to be 1,010 and 4,892 MW/(m2·K) for UNCD/a-C:H and UNCD/a-C films, respectively. The reasons for the hydrogenated film having lower interfacial conductance than the non-hydrogenated film are 1) the reduced number of carriers that contribute to heat transport and 2) the hydrogen atoms, which are preferentially located at the grain boundaries and enhance phonon scattering.

Pressure-induced transformations in amorphous silicon: A computational study

Energy Technology Data Exchange (ETDEWEB)

Garcez, K. M. S., E-mail: kmgarcez@ufma.br [Universidade Federal do Maranhão, 65700-000 Bacabal, Maranhão (Brazil); Antonelli, A., E-mail: aantone@ifi.unicamp.br [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-859 Campinas, São Paulo (Brazil)

2014-02-14

We study the transformations between amorphous phases of Si through molecular simulations using the environment dependent interatomic potential (EDIP) for Si. Our results show that upon pressure, the material undergoes a transformation from the low density amorphous (LDA) Si to the high density amorphous (HDA) Si. This transformation can be reversed by decompressing the material. This process, however, exhibits clear hysteresis, suggesting that the transformation LDA ↔ HDA is first-order like. The HDA phase is predominantly five-fold coordinated, whereas the LDA phase is the normal tetrahedrally bonded amorphous Si. The HDA phase at 400 K and 20 GPa was submitted to an isobaric annealing up to 800 K, resulting in a denser amorphous phase, which is structurally distinct from the HDA phase. Our results also show that the atomic volume and structure of this new amorphous phase are identical to those of the glass obtained by an isobaric quenching of the liquid in equilibrium at 2000 K and 20 GPa down to 400 K. The similarities between our results and those for amorphous ices suggest that this new phase is the very high density amorphous Si.

Pressure-induced transformations in amorphous silicon: A computational study

Science.gov (United States)

Garcez, K. M. S.; Antonelli, A.

2014-02-01

We study the transformations between amorphous phases of Si through molecular simulations using the environment dependent interatomic potential (EDIP) for Si. Our results show that upon pressure, the material undergoes a transformation from the low density amorphous (LDA) Si to the high density amorphous (HDA) Si. This transformation can be reversed by decompressing the material. This process, however, exhibits clear hysteresis, suggesting that the transformation LDA ↔ HDA is first-order like. The HDA phase is predominantly five-fold coordinated, whereas the LDA phase is the normal tetrahedrally bonded amorphous Si. The HDA phase at 400 K and 20 GPa was submitted to an isobaric annealing up to 800 K, resulting in a denser amorphous phase, which is structurally distinct from the HDA phase. Our results also show that the atomic volume and structure of this new amorphous phase are identical to those of the glass obtained by an isobaric quenching of the liquid in equilibrium at 2000 K and 20 GPa down to 400 K. The similarities between our results and those for amorphous ices suggest that this new phase is the very high density amorphous Si.

Topology preserving non-rigid image registration using time-varying elasticity model for MRI brain volumes.

Science.gov (United States)

Ahmad, Sahar; Khan, Muhammad Faisal

2015-12-01

In this paper, we present a new non-rigid image registration method that imposes a topology preservation constraint on the deformation. We propose to incorporate the time varying elasticity model into the deformable image matching procedure and constrain the Jacobian determinant of the transformation over the entire image domain. The motion of elastic bodies is governed by a hyperbolic partial differential equation, generally termed as elastodynamics wave equation, which we propose to use as a deformation model. We carried out clinical image registration experiments on 3D magnetic resonance brain scans from IBSR database. The results of the proposed registration approach in terms of Kappa index and relative overlap computed over the subcortical structures were compared against the existing topology preserving non-rigid image registration methods and non topology preserving variant of our proposed registration scheme. The Jacobian determinant maps obtained with our proposed registration method were qualitatively and quantitatively analyzed. The results demonstrated that the proposed scheme provides good registration accuracy with smooth transformations, thereby guaranteeing the preservation of topology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sensing of substratum rigidity and directional migration by fast-crawling cells

Science.gov (United States)

Okimura, Chika; Sakumura, Yuichi; Shimabukuro, Katsuya; Iwadate, Yoshiaki

2018-05-01

Living cells sense the mechanical properties of their surrounding environment and respond accordingly. Crawling cells detect the rigidity of their substratum and migrate in certain directions. They can be classified into two categories: slow-moving and fast-moving cell types. Slow-moving cell types, such as fibroblasts, smooth muscle cells, mesenchymal stem cells, etc., move toward rigid areas on the substratum in response to a rigidity gradient. However, there is not much information on rigidity sensing in fast-moving cell types whose size is ˜10 μ m and migration velocity is ˜10 μ m /min . In this study, we used both isotropic substrata with different rigidities and an anisotropic substratum that is rigid on the x axis but soft on the y axis to demonstrate rigidity sensing by fast-moving Dictyostelium cells and neutrophil-like differentiated HL-60 cells. Dictyostelium cells exerted larger traction forces on a more rigid isotropic substratum. Dictyostelium cells and HL-60 cells migrated in the "soft" direction on the anisotropic substratum, although myosin II-null Dictyostelium cells migrated in random directions, indicating that rigidity sensing of fast-moving cell types differs from that of slow types and is induced by a myosin II-related process.

Anodic electrochemical treatment of amorphous alloys

International Nuclear Information System (INIS)

Isaev, N.I.; Yakovlev, V.B.; Osipov, Eh.K.; Isaev, A.V.; Trofimova, E.A.; Vasil'ev, V.Yu.

1983-01-01

The aim of the investigation is to reveal peculiarities of the process of anodic oxidation and properties of anode oxide films, formed on the surface of amorphous alloys. Amorphous alloys on the base of rectifying metals of Zr-Ni, Zr-Cu-Ni, Zr-Al-Ni, Zr-Cu-Sn, Zr-Al, Zr-Mo systems are studied. Electrolytes which do not dissolve or weakly dissolve oxide film, such as boric acid electrolyte (40-45 g/l H 3 BO 3 and 18 cm 3 /l of the 25% aqueous NH 4 OH solution) and 20% H 2 SO 4 solution, are used for oxidation. Results of investigations, carried out on amorphous alloys, contaning noticeable quantities of non-rectifying components - Cu, Ni, Sn, Fe, Mo etc - have shown that non-rectifying components harden a process of anodic oxidation and decrease the current efficiency. Amorphous alloys, containing only rectifying components are oxidated in anodic way, the regularities of film growth being similar to those obtained for crystalline materials

Magnetic force microscopy characterization of heat and current treated Fe40Ni38Mo4B18 amorphous ribbons

International Nuclear Information System (INIS)

Garcia, Ignacio; Iturriza, Nuria; Jose del Val, Juan; Grande, Hans; Pomposo, Jose A.; Gonzalez, Julian

2010-01-01

The domain structure of a magnetostrictive Fe 40 Ni 38 Mo 4 B 18 amorphous ribbon has been studied using magnetic force microscopy (MFM) at room temperature. First, the evolution of the magnetic domain patterns as a function of the annealing temperature has been investigated. In samples heat treated at 250 and 450 deg. C for 1 h, a transformation from 90 deg. to 180 deg. domain wall has been clearly observed, while the sample heat treated at 700 deg. C for 1 h showed a magnetic phase fixed by the crystalline anisotropy. Additionally, the evolution of the magnetic domain structure by applying a DC current was recorded by the MFM technique. For current annealed samples at 1 A for 1, 30 and 60 min, a transformation between different domain patterns has been observed. Finally, in samples treated by the current annealing method under simultaneous stress, an increase of the annealing time gives rise to a different magnetic structure arising from the development of transverse magnetic anisotropy.

Anomalous magnetoresistance in amorphous metals

International Nuclear Information System (INIS)

Kuz'menko, V.M.; Vladychkin, A.N.; Mel'nikov, V.I.; Sudovtsev, A.I.

1984-01-01

The magnetoresistance of amorphous Bi, Ca, V and Yb films is investigated in fields up to 4 T at low temperatures. For all metals the magnetoresistance is positive, sharply decreases with growth of temperature and depends anomalously on the magnetic field strength. For amorphous superconductors the results agree satisfactorily with the theory of anomalous magnetoresistance in which allowance is made for scattering of electrons by the superconducting fluctuations

Rigid body formulation in a finite element context with contact interaction

Science.gov (United States)

Refachinho de Campos, Paulo R.; Gay Neto, Alfredo

2018-03-01

The present work proposes a formulation to employ rigid bodies together with flexible bodies in the context of a nonlinear finite element solver, with contact interactions. Inertial contributions due to distribution of mass of a rigid body are fully developed, considering a general pole position associated with a single node, representing a rigid body element. Additionally, a mechanical constraint is proposed to connect a rigid region composed by several nodes, which is useful for linking rigid/flexible bodies in a finite element environment. Rodrigues rotation parameters are used to describe finite rotations, by an updated Lagrangian description. In addition, the contact formulation entitled master-surface to master-surface is employed in conjunction with the rigid body element and flexible bodies, aiming to consider their interaction in a rigid-flexible multibody environment. New surface parameterizations are presented to establish contact pairs, permitting pointwise interaction in a frictional scenario. Numerical examples are provided to show robustness and applicability of the methods.

Electromechanical response of amorphous LaAlO3 thin film probed by scanning probe microscopies

Science.gov (United States)

Borowiak, Alexis S.; Baboux, Nicolas; Albertini, David; Vilquin, Bertrand; Saint Girons, Guillaume; Pelloquin, Sylvain; Gautier, Brice

2014-07-01

The electromechanical response of a 3 nm thick amorphous LaAlO3 layer obtained by molecular beam epitaxy has been studied using scanning probe microscopies. Although this kind of sample is not ferroelectric due to its amorphous nature, the resulting images are identical to what is generally obtained on truly ferroelectric samples probed by piezoresponse force microscopy: domains of apparently opposite polarisation are detected, and perfect, square shaped hysteresis loops are recorded. Moreover, written patterns are stable within 72 h. We discuss in the general case the possible origins of this behaviour in terms of charge injection, ionic conduction and motion of oxygen vacancies. In the case presented in this paper, since the writing process has been conducted with applied voltages lower than the injection threshold measured by conductive atomic force Microscopy, allowing to withdraw the hypothesis of charge injection in the sample, we propose that a bistable distribution of oxygen vacancies is responsible for this contrast.

Electromechanical response of amorphous LaAlO3 thin film probed by scanning probe microscopies

International Nuclear Information System (INIS)

Borowiak, Alexis S.; Baboux, Nicolas; Albertini, David; Gautier, Brice; Vilquin, Bertrand; Saint Girons, Guillaume; Pelloquin, Sylvain

2014-01-01

The electromechanical response of a 3 nm thick amorphous LaAlO 3 layer obtained by molecular beam epitaxy has been studied using scanning probe microscopies. Although this kind of sample is not ferroelectric due to its amorphous nature, the resulting images are identical to what is generally obtained on truly ferroelectric samples probed by piezoresponse force microscopy: domains of apparently opposite polarisation are detected, and perfect, square shaped hysteresis loops are recorded. Moreover, written patterns are stable within 72 h. We discuss in the general case the possible origins of this behaviour in terms of charge injection, ionic conduction and motion of oxygen vacancies. In the case presented in this paper, since the writing process has been conducted with applied voltages lower than the injection threshold measured by conductive atomic force Microscopy, allowing to withdraw the hypothesis of charge injection in the sample, we propose that a bistable distribution of oxygen vacancies is responsible for this contrast.

Elemental process of amorphization induced by electron irradiation in Si

International Nuclear Information System (INIS)

Yamasaki, Jun; Takeda, Seiji; Tsuda, Kenji

2002-01-01

We recently found that amorphization is induced in Si by electron irradiation. Examining the amorphization systematically, we have established the diagram of steady states under electron irradiation, either amorphous Si (a-Si) or crystalline Si (c-Si) as a function of incident electron energy, electron dose, and irradiation temperature. Utilizing transmission electron microscopy, electron energy filtered diffraction and electron energy-loss spectroscopy, we have characterized the atomic structure, the electronic structure, and the thermal stability of a-Si induced by electron irradiation. Based on the experimental data, we have also concluded that the amorphization is caused by the accumulation of not point defects but small cascade damages. Analyzing the change in the intensity of halo diffraction rings during amorphization, we have clarified that the smallest cascade damage that contributes to amorphization includes only about four Si atoms. This presumably supports the amorphization mechanism that four self-interstitial atoms form the quasistable structure I4 in c-Si and it becomes an amorphous embryo

Effect of rigid inclusions on sintering

International Nuclear Information System (INIS)

Rahaman, M.N.; De Jonghe, L.C.

1988-01-01

The predictions of recent theoretical studies on the effect of inert, rigid inclusions on the sintering of ceramic powder matrices are examined and compared with experimental data. The densification of glass matrix composites with inclusion volume fractions of ≤0.15 can be adequately explained by Scherer's theory for viscous sintering with rigid inclusions. Inclusions cause a vast reduction in the densification rates of polycrystalline matrix composites even at low inclusion volume fractions. Models put forward to explain the sintering of polycrystalline matrix composites are discussed

Rigid-Plastic Post-Buckling Analysis of Columns and Quadratic Plates

DEFF Research Database (Denmark)

Jönsson, Jeppe

2008-01-01

the compressive load as a function of the transverse displacement. An estimate of the magnitude of the transverse displacement prior to the forming of the collapse mechanism is introduced into the compressive load function, determined by the virtual work equation, thereby revealing a qualified estimate...... yield lines accommodate differential rotations of rigid parts and the area “collapse” yield lines accommodate local area changes of the rigid parts thereby preserving compatibility of the rigid parts of a plate. The approach will be illustrated for rigid plastic column analysis and for a quadratic plate...

Using containerless methods to develop amorphous pharmaceuticals.

Science.gov (United States)

Weber, J K R; Benmore, C J; Suthar, K J; Tamalonis, A J; Alderman, O L G; Sendelbach, S; Kondev, V; Yarger, J; Rey, C A; Byrn, S R

2017-01-01

Many pipeline drugs have low solubility in their crystalline state and require compounding in special dosage forms to increase bioavailability for oral administration. The use of amorphous formulations increases solubility and uptake of active pharmaceutical ingredients. These forms are rapidly gaining commercial importance for both pre-clinical and clinical use. Synthesis of amorphous drugs was performed using an acoustic levitation containerless processing method and spray drying. The structure of the products was investigated using in-situ high energy X-ray diffraction. Selected solvents for processing drugs were investigated using acoustic levitation. The stability of amorphous samples was measured using X-ray diffraction. Samples processed using both spray drying and containerless synthesis were compared. We review methods for making amorphous pharmaceuticals and present data on materials made by containerless processing and spray drying. It was shown that containerless processing using acoustic levitation can be used to make phase-pure forms of drugs that are known to be difficult to amorphize. The stability and structure of the materials was investigated in the context of developing and making clinically useful formulations. Amorphous compounds are emerging as an important component of drug development and for the oral delivery of drugs with low solubility. Containerless techniques can be used to efficiently synthesize small quantities of pure amorphous forms that are potentially useful in pre-clinical trials and for use in the optimization of clinical products. Developing new pharmaceutical products is an essential enterprise to improve patient outcomes. The development and application of amorphous pharmaceuticals to increase absorption is rapidly gaining importance and it provides opportunities for breakthrough research on new drugs. There is an urgent need to solve problems associated with making formulations that are both stable and that provide high

Damping of the domain walls motion in Co-based amorphous ribbons with helical magnetic anisotropy: Part III

International Nuclear Information System (INIS)

Zhmetko, D.N.; Zhmetko, S.D.

2009-01-01

The damping of the motion of domain walls of a sandwich domain structure by the eddy currents magnetic fields, the stray fields and the hysteresis friction fields is investigated. The blocking of the motion of domain walls by the eddy currents magnetic fields is discovered.

About deformation and rigidity in relativity

International Nuclear Information System (INIS)

Coll, Bartolome

2007-01-01

The notion of deformation involves that of rigidity. In relativity, starting from Born's early definition of rigidity, some other ones have been proposed, offering more or less interesting aspects but also accompanied of undesired or even pathological properties. In order to clarify the origin of these difficulties presented by the notion of rigidity in relativity, we analyze with some detail significant aspects of the unambiguous classical, Newtonian, notion. In particular, the relative character of its kinetic definition is pointed out, allowing to predict and to understand the limitations imposed by Herglotz-Noether theorem. Also, its equivalent dynamic definition is obtained and, in contrast, its absolute character is shown. But in spite of this absolute character, the dynamic definition is shown to be not extensible to relativity. The metric deformation of Minkowski space by the presence of a gravitational field is interpreted as a universal deformation, and it is shown that, under natural conditions, only a simple deformation law is possible, relating locally, but in an one-to-one way, gravitational fields and gauge classes of two-forms. We argue that fields of unit vectors associated to the internal gauge class of two-forms of every space-time (and, in particular, of Minkowski space-time) are the relativistic analogues of the classical accelerated observers, i.e. of the classical rigid motions. Some other consequences of the universal law of gravitational deformation are commented

Magnetic cluster mean-field description of spin glasses in amorphous La-Gd-Au alloys

International Nuclear Information System (INIS)

Poon, S.J.; Durand, J.

1978-03-01

Bulk magnetic properties of splat-cooled amorphous alloys of composition La/sub 80-x/Gd/sub x/Au 20 (0 less than or equal to x less than or equal to 80) were studied. Zero-field susceptibility, high-field magnetization (up to 75 kOe) and saturated remanence were measured between 1.8 and 290 0 K. Data were analyzed using a cluster mean-field approximation for the spin-glass and mictomagnetic alloys (x less than or equal to 56). Mean-field theories can account for the experimental freezing-temperatures of dilute spin-glasses in which the Ruderman-Kittel-Kasuya-Yosida interaction is dominant. For the dilute alloys, the role of amorphousness on the magnetic interactions is discussed. By extending the mean-field approximation, the concentrated spin-glasses are represented by rigid ferromagnetic clusters as individual spin-entities interacting via random forces. Scaling laws for the magnetization M and saturation remanent magnetization M/sub rs/ are obtained and presented graphically for the x less than or equal to 32 alloys in which M/x = g(H/x*, T/x), M/sub rs/(T)/x = M/sub rs/(0)/x/ exp (-α*T/x/sup p/) where x* is the concentration of clusters, α* is a constant, and p is the freezing-temperature exponent given by T/sub M/ infinity x/sup p/. It is found that p = 1 and 1.3 for the regions 4 less than or equal to x less than or equal to 40 respectively. An attempt is also made to account for the freezing temperatures of concentrated spin glasses. The strength of the interaction among clusters is determined from high-field magnetization measurements using the Larkin-Smith method modified for clusters. It is shown that for the x < 24 alloys, the size of the clusters can be correlated to the structural short-range order in the amorphous state. More concentrated alloys are marked by the emergence of cluster percolation

Genus Ranges of 4-Regular Rigid Vertex Graphs.

Science.gov (United States)

Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin

2015-01-01

A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2 n vertices ( n > 1), we prove that all intervals [ a, b ] for all a genus ranges. For graphs with 2 n - 1 vertices ( n ≥ 1), we prove that all intervals [ a, b ] for all a genus ranges. We also provide constructions of graphs that realize these ranges.

Photoexcitation-induced processes in amorphous semiconductors

Energy Technology Data Exchange (ETDEWEB)

Singh, Jai [School of Engineering and Logistics, Charles Darwin University, Darwin, NT 0909 (Australia)]. E-mail: jai.singh@cdu.edu.au

2005-07-30

Theories for the mechanism of photo-induced processes of photodarkening (PD), volume expansion (VE) in amorphous chalcogenides are presented. Rates of spontaneous emission of photons by radiative recombination of excitons in amorphous semiconductors are also calculated and applied to study the excitonic photoluminescence in a-Si:H. Results are compared with previous theories.

Photoconductivity of amorphous silicon-rigorous modelling

International Nuclear Information System (INIS)

Brada, P.; Schauer, F.

1991-01-01

It is our great pleasure to express our gratitude to Prof. Grigorovici, the pioneer of the exciting field of amorphous state by our modest contribution to this area. In this paper are presented the outline of the rigorous modelling program of the steady-state photoconductivity in amorphous silicon and related materials. (Author)

Photoexcitation-induced processes in amorphous semiconductors

International Nuclear Information System (INIS)

Singh, Jai

2005-01-01

Theories for the mechanism of photo-induced processes of photodarkening (PD), volume expansion (VE) in amorphous chalcogenides are presented. Rates of spontaneous emission of photons by radiative recombination of excitons in amorphous semiconductors are also calculated and applied to study the excitonic photoluminescence in a-Si:H. Results are compared with previous theories

Dual Quaternion Variational Integrator for Rigid Body Dynamic Simulation

OpenAIRE

Xu, Jiafeng; Halse, Karl Henning

2016-01-01

In rigid body dynamic simulations, often the algorithm is required to deal with general situations where both reference point and inertia matrix are arbitrarily de- fined. We introduce a novel Lie group variational integrator using dual quaternion for simulating rigid body dynamics in all six degrees of freedom. Dual quaternion is used to represent rigid body kinematics and one-step Lie group method is used to derive dynamic equations. The combination of these two becomes the first Lie group ...

Homogenization models for thin rigid structured surfaces and films.

Science.gov (United States)

Marigo, Jean-Jacques; Maurel, Agnès

2016-07-01

A homogenization method for thin microstructured surfaces and films is presented. In both cases, sound hard materials are considered, associated with Neumann boundary conditions and the wave equation in the time domain is examined. For a structured surface, a boundary condition is obtained on an equivalent flat wall, which links the acoustic velocity to its normal and tangential derivatives (of the Myers type). For a structured film, jump conditions are obtained for the acoustic pressure and the normal velocity across an equivalent interface (of the Ventcels type). This interface homogenization is based on a matched asymptotic expansion technique, and differs slightly from the classical homogenization, which is known to fail for small structuration thicknesses. In order to get insight into what causes this failure, a two-step homogenization is proposed, mixing classical homogenization and matched asymptotic expansion. Results of the two homogenizations are analyzed in light of the associated elementary problems, which correspond to problems of fluid mechanics, namely, potential flows around rigid obstacles.

Dynamical analysis of an orbiting three-rigid-body system

Energy Technology Data Exchange (ETDEWEB)

Pagnozzi, Daniele, E-mail: daniele.pagnozzi@strath.ac.uk, E-mail: james.biggs@strath.ac.uk; Biggs, James D., E-mail: daniele.pagnozzi@strath.ac.uk, E-mail: james.biggs@strath.ac.uk [Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow, Scotland (United Kingdom)

2014-12-10

The development of multi-joint-spacecraft mission concepts calls for a deeper understanding of their nonlinear dynamics to inform and enhance system design. This paper presents a study of a three-finite-shape rigid-body system under the action of an ideal central gravitational field. The aim of this paper is to gain an insight into the natural dynamics of this system. The Hamiltonian dynamics is derived and used to identify relative attitude equilibria of the system with respect to the orbital reference frame. Then a numerical investigation of the behaviour far from the equilibria is provided using tools from modern dynamical systems theory such as energy methods, phase portraits and Poincarè maps. Results reveal a complex structure of the dynamics as well as the existence of connections between some of the equilibria. Stable equilibrium configurations appear to be surrounded by very narrow regions of regular and quasi-regular motions. Trajectories evolve on chaotic motions in the rest of the domain.

Seismic response of bridge pier on rigid caisson foundation in soil stratum

Science.gov (United States)

Tsigginos, C.; Gerolymos, N.; Assimaki, D.; Gazetas, G.

2008-03-01

An analytical method to study the seismic response of a bridge pier supported on a rigid caisson foundation embedded in a deep soil stratum underlain by a homogeneous half space is developed. The method reproduces the kinematic and inertial responses, using translational and rotational distributed Winkler springs and dashpots to simulate the soil-caisson interaction. Closed-form solutions are given in the frequency domain for vertical harmonic S-wave excitation. Comparison with results from finite element (FE) analysis and other available solutions demonstrates the reliability of the model. Results from parametric studies are given for the kinematic and inertial responses. The modification of the fundamental period and damping ratio of the bridge due to soil-structure interaction is graphically illustrated.

Atomistic modeling of ion beam induced amorphization in silicon

International Nuclear Information System (INIS)

Pelaz, Lourdes; Marques, Luis A.; Lopez, Pedro; Santos, Ivan; Aboy, Maria; Barbolla, Juan

2005-01-01

Ion beam induced amorphization in Si has attracted significant interest since the beginning of the use of ion implantation for the fabrication of Si devices. Nowadays, a renewed interest in the modeling of amorphization mechanisms at atomic level has arisen due to the use of preamorphizing implants and high dopant implantation doses for the fabrication of nanometric-scale Si devices. In this work, we briefly describe the existing phenomenological and defect-based amorphization models. We focus on the atomistic model we have developed to describe ion beam induced amorphization in Si. In our model, the building block for the amorphous phase is the bond defect or IV pair, whose stability increases with the number of surrounding IV pairs. This feature explains the regrowth behavior of different damage topologies and the kinetics of the crystalline to amorphous transition. The model provides excellent quantitative agreement with experimental results

Effect of radiation-induced amorphization on smectite dissolution.

Science.gov (United States)

Fourdrin, C; Allard, T; Monnet, I; Menguy, N; Benedetti, M; Calas, G

2010-04-01

Effects of radiation-induced amorphization of smectite were investigated using artificial irradiation. Beams of 925 MeV Xenon ions with radiation dose reaching 73 MGy were used to simulate the effects generated by alpha recoil nuclei or fission products in the context of high level nuclear waste repository. Amorphization was controlled by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. An important coalescence of the smectite sheets was observed which lead to a loss of interparticle porosity. The amorphization is revealed by a loss of long-range structure and accompanied by dehydroxylation. The dissolution rate far-from-equilibrium shows that the amount of silica in solution is two times larger in the amorphous sample than in the reference clay, a value which may be enhanced by orders of magnitude when considering the relative surface area of the samples. Irradiation-induced amorphization thus facilitates dissolution of the clay-derived material. This has to be taken into account for the safety assessment of high level nuclear waste repository, particularly in a scenario of leakage of the waste package which would deliver alpha emitters able to amorphize smectite after a limited period of time.

Production of amorphous alloys by ion implantation

International Nuclear Information System (INIS)

Grant, W.A.; Chadderton, L.T.; Johnson, E.

1978-01-01

Recent data are reported on the use of ion implantation to produce amorphous metallic alloys. In particular data on the dose dependence of the crystalline to amorphous transition induced by P + implantation of nickel is presented. (Auth.)

Optoelectronic transport properties in amorphous/crystalline silicon solar cell heterojunctions measured by frequency-domain photocarrier radiometry: Multi-parameter measurement reliability and precision studies

International Nuclear Information System (INIS)

Zhang, Y.; Melnikov, A.; Mandelis, A.; Halliop, B.; Kherani, N. P.; Zhu, R.

2015-01-01

A theoretical one-dimensional two-layer linear photocarrier radiometry (PCR) model including the presence of effective interface carrier traps was used to evaluate the transport parameters of p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) passivated by an intrinsic hydrogenated amorphous silicon (i-layer) nanolayer. Several crystalline Si heterojunction structures were examined to investigate the influence of the i-layer thickness and the doping concentration of the a-Si:H layer. The experimental data of a series of heterojunction structures with intrinsic thin layers were fitted to PCR theory to gain insight into the transport properties of these devices. The quantitative multi-parameter results were studied with regard to measurement reliability (uniqueness) and precision using two independent computational best-fit programs. The considerable influence on the transport properties of the entire structure of two key parameters that can limit the performance of amorphous thin film solar cells, namely, the doping concentration of the a-Si:H layer and the i-layer thickness was demonstrated. It was shown that PCR can be applied to the non-destructive characterization of a-Si:H/c-Si heterojunction solar cells yielding reliable measurements of the key parameters

Optoelectronic transport properties in amorphous/crystalline silicon solar cell heterojunctions measured by frequency-domain photocarrier radiometry: multi-parameter measurement reliability and precision studies.

Science.gov (United States)

Zhang, Y; Melnikov, A; Mandelis, A; Halliop, B; Kherani, N P; Zhu, R

2015-03-01

A theoretical one-dimensional two-layer linear photocarrier radiometry (PCR) model including the presence of effective interface carrier traps was used to evaluate the transport parameters of p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) passivated by an intrinsic hydrogenated amorphous silicon (i-layer) nanolayer. Several crystalline Si heterojunction structures were examined to investigate the influence of the i-layer thickness and the doping concentration of the a-Si:H layer. The experimental data of a series of heterojunction structures with intrinsic thin layers were fitted to PCR theory to gain insight into the transport properties of these devices. The quantitative multi-parameter results were studied with regard to measurement reliability (uniqueness) and precision using two independent computational best-fit programs. The considerable influence on the transport properties of the entire structure of two key parameters that can limit the performance of amorphous thin film solar cells, namely, the doping concentration of the a-Si:H layer and the i-layer thickness was demonstrated. It was shown that PCR can be applied to the non-destructive characterization of a-Si:H/c-Si heterojunction solar cells yielding reliable measurements of the key parameters.

Amorphization reaction in thin films of elemental Cu and Y

Science.gov (United States)

Johnson, R. W.; Ahn, C. C.; Ratner, E. R.

1989-10-01

Compositionally modulated thin films of Cu and Y were prepared in an ultrahigh-vacuum dc ion-beam deposition chamber. The amorphization reaction was monitored by in situ x-ray-diffraction measurements. Growth of amorphous Cu1-xYx is observed at room temperature with the initial formation of a Cu-rich amorphous phase. Further annealing in the presence of unreacted Y leads to Y enrichment of the amorphous phase. Growth of crystalline CuY is observed for T=469 K. Transmission-electron-microscopy measurements provide real-space imaging of the amorphous interlayer and growth morphology. Models are developed, incorporating metastable interfacial and bulk free-energy diagrams, for the early stage of the amorphization reaction.

Heavy ions amorphous semiconductors irradiation study

International Nuclear Information System (INIS)

Benmalek, M.

1978-01-01

The behavior of amorphous semiconductors (germanium and germanium and arsenic tellurides) under ion bombardment at energies up to 2 MeV was studied. The irradiation induced modifications were followed using electrical parameter changes (resistivity and activation energy) and by means of the transmission electron microscopy observations. The electrical conductivity enhancement of the irradiated samples was interpreted using the late conduction theories in amorphous compounds. In amorphous germanium, Electron Microscopy showed the formations of 'globules', these defects are similar to voids observed in irradiated metals. The displacement cascade theory was used for the interpretation of the irradiation induced defects formation and a coalescence mechanism of growth was pointed out for the vacancy agglomeration [fr

Amorphous surface layers in Ti-implanted Fe

International Nuclear Information System (INIS)

Knapp, J.A.; Follstaedt, D.M.; Picraux, S.T.

1979-01-01

Implanting Ti into high-purity Fe results in an amorphous surface layer which is composed of not only Fe and Ti, but also C. Implantations were carried out at room temperature over the energy range 90 to 190 keV and fluence range 1 to 2 x 10 16 at/cm 2 . The Ti-implanted Fe system has been characterized using transmission electron microscopy (TEM), ion backscattering and channeling analysis, and (d,p) nuclear reaction analysis. The amorphous layer was observed to form at the surface and grow inward with increasing Ti fluence. For an implant of 1 x 10 17 Ti/cm 2 at 180 keV the layer thickness was 150 A, while the measured range of the implanted Ti was approx. 550 A. This difference is due to the incorporation of C into the amorphous alloy by C being deposited on the surface during implantation and subsequently diffusing into the solid. Our results indicate that C is an essential constituent of the amorphous phase for Ti concentrations less than or equal to 10 at. %. For the 1 x 10 17 Ti/cm 2 implant, the concentration of C in the amorphous phase was approx. 25 at. %, while that of Ti was only approx. 3 at. %. A higher fluence implant of 2 x 10 17 Ti/cm 2 produced an amorphous layer with a lower C concentration of approx. 10 at. % and a Ti concentration of approx. 20 at. %

Generalized melting criterion for beam-induced amorphization

International Nuclear Information System (INIS)

Lam, N. Q.; Okamoto, Paul R.

1993-09-01

Recent studies have shown that the mean-square static atomic displacements provide a generic measure of the enthalpy stored in the lattice in the form of chemical and topological disorder, and that the effect of the displacements on the softening of shear elastic constants is identical to that of heating. This finding lends support to a generalized form of the Lindemann phenomenological melting criterion and leads to a natural interpretion of crystalline-to-amorphous transformations as defect-induced melting of metastable crystals driven beyond a critical state of disorder where the melting temperature falls below the glass-transition temperature. Application of the generalized Lindemann criterion to both the crystalline and amorphous phases indicates that the enthalpies of the two phases become identical when their shear moduli become equal. This thermo-elastic rule provides a basis for predicting the relative susceptibility of compounds to amorphization in terms of their elastic properties as measured by Debye temperatures. The present approach can explain many of the basic findings on beam-induced amorphization of intermetallic compounds as well as amorphous phase formation associated with ion implantation, ion-beam mixing and other solid-state processes

The Structure of Liquid and Amorphous Hafnia

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Leighanne C. Gallington

2017-11-01

Full Text Available Understanding the atomic structure of amorphous solids is important in predicting and tuning their macroscopic behavior. Here, we use a combination of high-energy X-ray diffraction, neutron diffraction, and molecular dynamics simulations to benchmark the atomic interactions in the high temperature stable liquid and low-density amorphous solid states of hafnia. The diffraction results reveal an average Hf–O coordination number of ~7 exists in both the liquid and amorphous nanoparticle forms studied. The measured pair distribution functions are compared to those generated from several simulation models in the literature. We have also performed ab initio and classical molecular dynamics simulations that show density has a strong effect on the polyhedral connectivity. The liquid shows a broad distribution of Hf–Hf interactions, while the formation of low-density amorphous nanoclusters can reproduce the sharp split peak in the Hf–Hf partial pair distribution function observed in experiment. The agglomeration of amorphous nanoparticles condensed from the gas phase is associated with the formation of both edge-sharing and corner-sharing HfO6,7 polyhedra resembling that observed in the monoclinic phase.

Effect of amorphous lamella on the crack propagation behavior of crystalline Mg/amorphous Mg-Al nanocomposites

Science.gov (United States)

Hai-Yang, Song; Yu-Long, Li

2016-02-01

The effects of amorphous lamella on the crack propagation behavior in crystalline/amorphous (C/A) Mg/Mg-Al nanocomposites under tensile loading are investigated using the molecular dynamics simulation method. The sample with an initial crack of orientation [0001] is considered here. For the nano-monocrystal Mg, the crack growth exhibits brittle cleavage. However, for the C/A Mg/Mg-Al nanocomposites, the ‘double hump’ behavior can be observed in all the stress-strain curves regardless of the amorphous lamella thickness. The results indicate that the amorphous lamella plays a critical role in the crack deformation, and it can effectively resist the crack propagation. The above mentioned crack deformation behaviors are also disclosed and analyzed in the present work. The results here provide a strategy for designing the high-performance hexagonal-close-packed metal and alloy materials. Project supported by the National Natural Science Foundation of China (Grant Nos. 11372256 and 11572259), the 111 Project (Grant No. B07050), the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-12-1046), and the Program for New Scientific and Technological Star of Shaanxi Province, China (Grant No. 2012KJXX-39).

The Almost Periodic Rigidity of Crystallographic Bar-Joint Frameworks

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Ghada Badri

2014-04-01

Full Text Available A crystallographic bar-joint framework, C in Rd, is shown to be almost periodically infinitesimally rigid if and only if it is strictly periodically infinitesimally rigid and the rigid unit mode (RUM spectrum, Ω (C, is a singleton. Moreover, the almost periodic infinitesimal flexes of C are characterised in terms of a matrix-valued function, ΦC(z, on the d-torus, Td, determined by a full rank translation symmetry group and an associated motif of joints and bars.

Wobbling motion: A γ-rigid or γ-soft mode?

International Nuclear Information System (INIS)

Casten, R.F.; McCutchan, E.A.; Beausang, C.W.; Zamfir, N.V.; Zhang Jingye

2003-01-01

For even-even nuclei, it is shown that the predicted B(E2) values from the odd spin states of the quasi-γ band in a γ-soft nucleus to the yrast band are quite similar to those predicted for the one-phonon wobbling mode of a rigidly triaxial nucleus. This suggests that the observation of wobbling points to axial asymmetry, but not necessarily to rigid triaxiality. However, another observable that does distinguish γ-soft from γ-rigid structure is identified

The effect of the lateral interactions on the critical behavior of long straight rigid rods on two-dimensional lattices

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A. J. Ramirez-Pastor

2009-09-01

Full Text Available Using Monte Carlo simulations and finite-size scaling analysis, the critical behavior of attractive rigid rods of length $k$ ($k$-mers on square lattices at intermediate density has been studied. A nematic phase, characterized by a big domain of parallel $k$-mers, was found. This ordered phase is separated from the isotropic state by a continuous transition occurring at a intermediate density $heta_c$, which increases linearly with the magnitude of the lateral interactions.

Synthesis of amorphous acid iron phosphate nanoparticles

International Nuclear Information System (INIS)

Palacios, E.; Leret, P.; Fernández, J. F.; Aza, A. H. De; Rodríguez, M. A.

2012-01-01

A simple method to precipitate nanoparticles of iron phosphate with acid character has been developed in which the control of pH allows to obtain amorphous nanoparticles. The acid aging of the precipitated amorphous nanoparticles favored the P–O bond strength that contributes to the surface reordering, the surface roughness and the increase of the phosphate acid character. The thermal behavior of the acid iron phosphate nanoparticles has been also studied and the phosphate polymerization at 400 °C produces strong compacts of amorphous nanoparticles with interconnected porosity.

Rigid Spine Syndrome among Children in Oman

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Roshan Koul

2015-08-01

Full Text Available Objectives: Rigidity of the spine is common in adults but is rarely observed in children. The aim of this study was to report on rigid spine syndrome (RSS among children in Oman. Methods: Data on children diagnosed with RSS were collected consecutively at presentation between 1996 and 2014 at the Sultan Qaboos University Hospital (SQUH in Muscat, Oman. A diagnosis of RSS was based on the patient’s history, clinical examination, biochemical investigations, electrophysiological findings, neuro-imaging and muscle biopsy. Atrophy of the paraspinal muscles, particularly the erector spinae, was the diagnostic feature; this was noted using magnetic resonance imaging of the spine. Children with disease onset in the paraspinal muscles were labelled as having primary RSS or rigid spinal muscular dystrophy. Secondary RSS was classified as RSS due to the late involvement of other muscle diseases. Results: Over the 18-year period, 12 children were included in the study, with a maleto- female ratio of 9:3. A total of 10 children were found to have primary RSS or rigid spinal muscular dystrophy syndrome while two had secondary RSS. Onset of the disease ranged from birth to 18 months of age. A family history was noted, with two siblings from one family and three siblings from another (n = 5. On examination, children with primary RSS had typical features of severe spine rigidity at onset, with the rest of the neurological examination being normal. Conclusion: RSS is a rare disease with only 12 reported cases found at SQUH during the study period. Cases of primary RSS should be differentiated from the secondary type.

Amorphous superconductors

International Nuclear Information System (INIS)

Missell, F.P.

1985-01-01

We describe briefly the strong coupling superconductivity observed in amorphous alloys based upon simple metals. For transition metal alloys we discuss the behavior of the superconducting transition temperature T c , the upper critical field H (sub)c2 and the critical current J c . A survey of current problems is presented. (author) [pt

Quantum mechanics of a generalised rigid body

International Nuclear Information System (INIS)

Gripaios, Ben; Sutherland, Dave

2016-01-01

We consider the quantum version of Arnold’s generalisation of a rigid body in classical mechanics. Thus, we quantise the motion on an arbitrary Lie group manifold of a particle whose classical trajectories correspond to the geodesics of any one-sided-invariant metric. We show how the derivation of the spectrum of energy eigenstates can be simplified by making use of automorphisms of the Lie algebra and (for groups of type I) by methods of harmonic analysis. We show how the method can be extended to cosets, generalising the linear rigid rotor. As examples, we consider all connected and simply connected Lie groups up to dimension 3. This includes the universal cover of the archetypical rigid body, along with a number of new exactly solvable models. We also discuss a possible application to the topical problem of quantising a perfect fluid. (paper)

Waggawagga-CLI: A command-line tool for predicting stable single α-helices (SAH-domains, and the SAH-domain distribution across eukaryotes.

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Dominic Simm

Full Text Available Stable single-alpha helices (SAH-domains function as rigid connectors and constant force springs between structural domains, and can provide contact surfaces for protein-protein and protein-RNA interactions. SAH-domains mainly consist of charged amino acids and are monomeric and stable in polar solutions, characteristics which distinguish them from coiled-coil domains and intrinsically disordered regions. Although the number of reported SAH-domains is steadily increasing, genome-wide analyses of SAH-domains in eukaryotic genomes are still missing. Here, we present Waggawagga-CLI, a command-line tool for predicting and analysing SAH-domains in protein sequence datasets. Using Waggawagga-CLI we predicted SAH-domains in 24 datasets from eukaryotes across the tree of life. SAH-domains were predicted in 0.5 to 3.5% of the protein-coding content per species. SAH-domains are particularly present in longer proteins supporting their function as structural building block in multi-domain proteins. In human, SAH-domains are mainly used as alternative building blocks not being present in all transcripts of a gene. Gene ontology analysis showed that yeast proteins with SAH-domains are particular enriched in macromolecular complex subunit organization, cellular component biogenesis and RNA metabolic processes, and that they have a strong nuclear and ribonucleoprotein complex localization and function in ribosome and nucleic acid binding. Human proteins with SAH-domains have roles in all types of RNA processing and cytoskeleton organization, and are predicted to function in RNA binding, protein binding involved in cell and cell-cell adhesion, and cytoskeletal protein binding. Waggawagga-CLI allows the user to adjust the stabilizing and destabilizing contribution of amino acid interactions in i,i+3 and i,i+4 spacings, and provides extensive flexibility for user-designed analyses.

Electromechanical response of amorphous LaAlO{sub 3} thin film probed by scanning probe microscopies

Energy Technology Data Exchange (ETDEWEB)

Borowiak, Alexis S.; Baboux, Nicolas; Albertini, David; Gautier, Brice, E-mail: brice.gautier@insa-lyon.fr [Institut des nanotechnologies de Lyon (INL), Institut National des Sciences Appliquées de Lyon, Université de Lyon, UMR CNRS 5270, 7 Avenue Capelle, F-69621 Villeurbanne Cedex (France); Vilquin, Bertrand; Saint Girons, Guillaume; Pelloquin, Sylvain [Institut des nanotechnologies de Lyon (INL), Ecole Centrale de Lyon, Université de Lyon, UMR CNRS 5270, 36 Avenue Guy de Collongues, F-69134 Ecully Cedex (France)

2014-07-07

The electromechanical response of a 3 nm thick amorphous LaAlO{sub 3} layer obtained by molecular beam epitaxy has been studied using scanning probe microscopies. Although this kind of sample is not ferroelectric due to its amorphous nature, the resulting images are identical to what is generally obtained on truly ferroelectric samples probed by piezoresponse force microscopy: domains of apparently opposite polarisation are detected, and perfect, square shaped hysteresis loops are recorded. Moreover, written patterns are stable within 72 h. We discuss in the general case the possible origins of this behaviour in terms of charge injection, ionic conduction and motion of oxygen vacancies. In the case presented in this paper, since the writing process has been conducted with applied voltages lower than the injection threshold measured by conductive atomic force Microscopy, allowing to withdraw the hypothesis of charge injection in the sample, we propose that a bistable distribution of oxygen vacancies is responsible for this contrast.

Defects in Amorphous Semiconductors: The Case of Amorphous Indium Gallium Zinc Oxide

Science.gov (United States)

de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

2018-05-01

Based on a rational classification of defects in amorphous materials, we propose a simplified model to describe intrinsic defects and hydrogen impurities in amorphous indium gallium zinc oxide (a -IGZO). The proposed approach consists of organizing defects into two categories: point defects, generating structural anomalies such as metal—metal or oxygen—oxygen bonds, and defects emerging from changes in the material stoichiometry, such as vacancies and interstitial atoms. Based on first-principles simulations, it is argued that the defects originating from the second group always act as perfect donors or perfect acceptors. This classification simplifies and rationalizes the nature of defects in amorphous phases. In a -IGZO, the most important point defects are metal—metal bonds (or small metal clusters) and peroxides (O - O single bonds). Electrons are captured by metal—metal bonds and released by the formation of peroxides. The presence of hydrogen can lead to two additional types of defects: metal-hydrogen defects, acting as acceptors, and oxygen-hydrogen defects, acting as donors. The impact of these defects is linked to different instabilities observed in a -IGZO. Specifically, the diffusion of hydrogen and oxygen is connected to positive- and negative-bias stresses, while negative-bias illumination stress originates from the formation of peroxides.

Customizable rigid head fixation for infants: technical note.

Science.gov (United States)

Udayakumaran, Suhas; Onyia, Chiazor U

2016-01-01

The need and advantages of rigid fixation of the head in cranial surgeries are well documented (Berryhill et al., Otolaryngol Head Neck Surg 121:269-273, 1999). Head fixation for neurosurgical procedures in infants and in early years has been a challenge and is fraught with risk. Despite the fact that pediatric pins are designed, rigid head fixation involving direct application of pins to the head of infants and slightly older children is still generally not safe (Agrawal and Steinbok, Childs Nerv Syst 22:1473-1474, 2006). Yet, there are some surgeries in which some form of rigid fixation is required (Agrawal and Steinbok, Childs Nerv Syst 22:1473-1474, 2006). We describe a simple technique to achieve rigid fixation of the head in infants for neurosurgical procedures. This involves applying a head band made of Plaster of Paris (POP) around the head and then applying the fixation pins of the fixation frame directly on to the POP. We have used this technique of head fixation successfully for infants with no complications.

"Mind the trap": mindfulness practice reduces cognitive rigidity.

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Jonathan Greenberg

Full Text Available Two experiments examined the relation between mindfulness practice and cognitive rigidity by using a variation of the Einstellung water jar task. Participants were required to use three hypothetical jars to obtain a specific amount of water. Initial problems were solvable by the same complex formula, but in later problems ("critical" or "trap" problems solving was possible by an additional much simpler formula. A rigidity score was compiled through perseverance of the complex formula. In Experiment 1, experienced mindfulness meditators received significantly lower rigidity scores than non-meditators who had registered for their first meditation retreat. Similar results were obtained in randomized controlled Experiment 2 comparing non-meditators who underwent an eight meeting mindfulness program with a waiting list group. The authors conclude that mindfulness meditation reduces cognitive rigidity via the tendency to be "blinded" by experience. Results are discussed in light of the benefits of mindfulness practice regarding a reduced tendency to overlook novel and adaptive ways of responding due to past experience, both in and out of the clinical setting.

Rigidity of outermost MOTS: the initial data version

Science.gov (United States)

Galloway, Gregory J.

2018-03-01

In the paper Commun Anal Geom 16(1):217-229, 2008, a rigidity result was obtained for outermost marginally outer trapped surfaces (MOTSs) that do not admit metrics of positive scalar curvature. This allowed one to treat the "borderline case" in the author's work with R. Schoen concerning the topology of higher dimensional black holes (Commun Math Phys 266(2):571-576, 2006). The proof of this rigidity result involved bending the initial data manifold in the vicinity of the MOTS within the ambient spacetime. In this note we show how to circumvent this step, and thereby obtain a pure initial data version of this rigidity result and its consequence concerning the topology of black holes.

APPLICATION OF RIGID LINKS IN STRUCTURAL DESIGN MODELS

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Sergey Yu. Fialko

2017-09-01

Full Text Available A special finite element modelling rigid links is proposed for the linear static and buckling analysis. Unlike the classical approach based on the theorems of rigid body kinematics, the proposed approach preserves the similarity between the adjacency graph for a sparse matrix and the adjacency graph for nodes of the finite element model, which allows applying sparse direct solvers more effectively. Besides, the proposed approach allows significantly reducing the number of nonzero entries in the factored stiffness matrix in comparison with the classical one, which greatly reduces the duration of the solution. For buckling problems of structures containing rigid bodies, this approach gives correct results. Several examples demonstrate its efficiency.

Intrinsic charge trapping in amorphous oxide films: status and challenges

Science.gov (United States)

Strand, Jack; Kaviani, Moloud; Gao, David; El-Sayed, Al-Moatasem; Afanas’ev, Valeri V.; Shluger, Alexander L.

2018-06-01

We review the current understanding of intrinsic electron and hole trapping in insulating amorphous oxide films on semiconductor and metal substrates. The experimental and theoretical evidences are provided for the existence of intrinsic deep electron and hole trap states stemming from the disorder of amorphous metal oxide networks. We start from presenting the results for amorphous (a) HfO2, chosen due to the availability of highest purity amorphous films, which is vital for studying their intrinsic electronic properties. Exhaustive photo-depopulation spectroscopy measurements and theoretical calculations using density functional theory shed light on the atomic nature of electronic gap states responsible for deep electron trapping observed in a-HfO2. We review theoretical methods used for creating models of amorphous structures and electronic structure calculations of amorphous oxides and outline some of the challenges in modeling defects in amorphous materials. We then discuss theoretical models of electron polarons and bi-polarons in a-HfO2 and demonstrate that these intrinsic states originate from low-coordinated ions and elongated metal-oxygen bonds in the amorphous oxide network. Similarly, holes can be captured at under-coordinated O sites. We then discuss electron and hole trapping in other amorphous oxides, such as a-SiO2, a-Al2O3, a-TiO2. We propose that the presence of low-coordinated ions in amorphous oxides with electron states of significant p and d character near the conduction band minimum can lead to electron trapping and that deep hole trapping should be common to all amorphous oxides. Finally, we demonstrate that bi-electron trapping in a-HfO2 and a-SiO2 weakens Hf(Si)–O bonds and significantly reduces barriers for forming Frenkel defects, neutral O vacancies and O2‑ ions in these materials. These results should be useful for better understanding of electronic properties and structural evolution of thin amorphous films under carrier injection

Solid state characterization of commercial crystalline and amorphous atorvastatin calcium samples.

Science.gov (United States)

Shete, Ganesh; Puri, Vibha; Kumar, Lokesh; Bansal, Arvind K

2010-06-01

Atorvastatin calcium (ATC), an anti-lipid BCS class II drug, is marketed in crystalline and amorphous solid forms. The objective of this study was to perform solid state characterization of commercial crystalline and amorphous ATC drug samples available in the Indian market. Six samples each of crystalline and amorphous ATC were characterized using X-ray powder diffractometry (XRPD), differential scanning calorimetry (DSC), thermogravimetric analysis, Karl Fisher titrimetry, microscopy (hot stage microscopy, scanning electron microscopy), contact angle, and intrinsic dissolution rate (IDR). All crystalline ATC samples were found to be stable form I, however one sample possessed polymorphic impurity, evidenced in XRPD and DSC analysis. Amongst the amorphous ATC samples, XRPD demonstrated five samples to be amorphous 'form 27', while, one matched amorphous 'form 23'. Thermal behavior of amorphous ATC samples was compared to amorphous ATC generated by melt quenching in DSC. ATC was found to be an excellent glass former with T(g)/T(m) of 0.95. Residual crystallinity was detected in two of the amorphous samples by complementary use of conventional and modulated DSC techniques. The wettability and IDR of all amorphous samples was found to be higher than the crystalline samples. In conclusion, commercial ATC samples exhibited diverse solid state behavior that can impact the performance and stability of the dosage forms.

In search of amorphization-resistant boron carbide

International Nuclear Information System (INIS)

Subhash, Ghatu; Awasthi, Amnaya P.; Kunka, Cody; Jannotti, Phillip; DeVries, Matthew

2016-01-01

Despite its superior mechanical properties, boron carbide suffers from amorphization, a pressure-induced phenomenon that disturbs crystalline order and likely reduces shear strength. Numerous experimental and computational studies have investigated the structure and origins of amorphization, yet strategies to mitigate this deleterious phenomenon elude. However, recent investigations have revealed three new research avenues for addressing this issue. First, we identify crystallographic cage spaces that may accommodate foreign atoms to potentially prevent structural collapse. Second, we propose polymorph-level tailoring through strict control of processing conditions. Finally, we demonstrate that reducing grain size to nanometer scale increases hardness and may counter amorphization.

Durable bistable auxetics made of rigid solids

Science.gov (United States)

Shang, Xiao; Liu, Lu; Rafsanjani, Ahmad; Pasini, Damiano

2018-02-01

Bistable Auxetic Metamaterials (BAMs) are a class of monolithic perforated periodic structures with negative Poisson's ratio. Under tension, a BAM can expand and reach a second state of equilibrium through a globally large shape transformation that is ensured by the flexibility of its elastomeric base material. However, if made from a rigid polymer, or metal, BAM ceases to function due to the inevitable rupture of its ligaments. The goal of this work is to extend the unique functionality of the original kirigami architecture of BAM to a rigid solid base material. We use experiments and numerical simulations to assess performance, bistability and durability of rigid BAMs at 10,000 cycles. Geometric maps are presented to elucidate the role of the main descriptors of BAM architecture. The proposed design enables the realization of BAM from a large palette of materials, including elastic-perfectly plastic materials and potentially brittle materials.

Utility of semi-rigid thoracoscopy in undiagnosed exudative pleural effusion.

Science.gov (United States)

Nattusamy, Loganathan; Madan, Karan; Mohan, Anant; Hadda, Vijay; Jain, Deepali; Madan, Neha Kawatra; Arava, Sudheer; Khilnani, Gopi C; Guleria, Randeep

2015-01-01

Semi-rigid thoracoscopy is a safe and efficacious procedure in patients with undiagnosed pleural effusion. Literature on its utility from developing countries is limited. We herein describe our initial experience on the utility of semi-rigid thoracoscopy from a tertiary care teaching and referral center in north India. We also perform a systematic review of studies reporting the utility of semi-rigid thoracoscopy from India. The primary objective was to evaluate the diagnostic utility of semi-rigid thoracoscopy in patients with undiagnosed exudative pleural effusion. Semi-rigid thoracoscopy was performed under local anesthesia and conscious sedation in the bronchoscopy suite. A total of 48 patients underwent semi-rigid thoracoscopy between August 2012 and December 2013 for undiagnosed pleural effusion. Mean age was 50.9 ± 14.1 years (range: 17-78 years). Pre-procedure clinico-radiological diagnoses were malignant pleural effusion [36 patients (75%)], tuberculosis (TB) [10 (20.83%) patients], and empyema [2 patients (4.17%)]. Patients with empyema underwent the procedure for pleural biopsy, optimal placement of intercostal tube and adhesiolysis. Thoracoscopic pleural biopsy diagnosed pleural malignancy in 30 (62.5%) patients and TB in 2 (4.17%) patients. Fourteen (29.17%) patients were diagnosed with non-specific pleuritis and normal pleura was diagnosed on a pleural biopsy in 2 (4.17%) patients. Overall, a definitive diagnosis of either pleural malignancy or TB was obtained in 32 (66.7%) patients. Combined overall sensitivity, specificity, positive predictive value and negative predictive value of thoracoscopic pleural biopsy for malignant pleural effusion were 96.77%, 100%, 100% and 66.67%, respectively. There was no procedure-related mortality. On performing a systematic review of literature, four studies on semi-rigid thoracoscopy from India were identified. Semi-rigid thoracoscopy is a safe and efficacious procedure in patients with undiagnosed exudative

Achievement report for fiscal 1984 on Sunshine Program-entrusted research and development. Research and development of amorphous solar cells (Theoretical research on amorphous silicon electronic states by computer-aided simulation); 1984 nendo amorphous taiyo denchi no kenkyu kaihatsu seika hokokusho. Keisanki simulation ni yoru amorphous silicon no denshi jotai no rironteki kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1985-04-01

Research on the basic physical properties of amorphous silicon materials and for the development of materials for thermally stable amorphous silicon is conducted through theoretical reasoning and computer-aided simulation. In the effort at achieving a high conversion efficiency using an amorphous silicon alloy, a process of realizing desired photoabsorption becomes possible when the correlation between the atomic structure and the photoabsorption coefficient is clearly established and the atomic structure is manipulated. In this connection, analytical studies are conducted to determine how microscopic structures are reflected on macroscopic absorption coefficients. In the computer-aided simulation, various liquid structures and amorphous structures are worked out, which is for the atom-level characterization of structures with topological disturbances, such as amorphous structures. Glass transition is simulated using a molecular kinetic method, in particular, and the melting of crystals, crystallization of liquids, and vitrification (conversion into the amorphous state) are successfully realized, though in a computer-aided simulation, for the first time in the world. (NEDO)

Challenges in amorphous silicon solar cell technology

NARCIS (Netherlands)

Swaaij, van R.A.C.M.M.; Zeman, M.; Korevaar, B.A.; Smit, C.; Metselaar, J.W.; Sanden, van de M.C.M.

2000-01-01

Hydrogenated amorphous silicon is nowadays extensively used for a range of devices, amongst others solar cells, Solar cell technology has matured over the last two decades and resulted in conversion efficiencies in excess of 15%. In this paper the operation of amorphous silicon solar cells is

Surface magnetic structures in amorphous ferromagnetic microwires

Energy Technology Data Exchange (ETDEWEB)

Usov, N.A., E-mail: usov@obninsk.ru [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, IZMIRAN, 108840 Troitsk, Moscow (Russian Federation); Serebryakova, O.N.; Gudoshnikov, S.A. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, IZMIRAN, 108840 Troitsk, Moscow (Russian Federation); Tarasov, V.P. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation)

2017-05-01

The spatial period of magnetization perturbations that occur near the surface of magnetic nanotube or nanowire under the influence of surface magnetic anisotropy is determined by means of numerical simulation as a function of the sample geometry and material parameters. The surface magnetization distribution obtained is then used to estimate the period of the surface magnetic texture in amorphous microwire of several micrometers in diameter by means of appropriate variational procedure. The period of the surface magnetic texture in amorphous microwire is found to be significantly smaller than the wire diameter. - Highlights: • Magnetic structure may arise near the magnetic nanotube surface under the influence of surface magnetic anisotropy. • The period of the surface magnetization pattern is calculated as a function of the sample geometry. • Similar magnetic structure may exist in amorphous microwire of several micrometers in diameter. • The period of the surface magnetic structure in amorphous wire is found to be significantly smaller than the wire diameter.

Inverted amorphous silicon solar cell utilizing cermet layers

Science.gov (United States)

Hanak, Joseph J.

1979-01-01

An amorphous silicon solar cell incorporating a transparent high work function metal cermet incident to solar radiation and a thick film cermet contacting the amorphous silicon opposite to said incident surface.

Algebraic Methods for Counting Euclidean Embeddings of Rigid Graphs

NARCIS (Netherlands)

I.Z. Emiris; E.P. Tsigaridas; A. Varvitsiotis (Antonios); E.R. Gasner

2009-01-01

textabstract The study of (minimally) rigid graphs is motivated by numerous applications, mostly in robotics and bioinformatics. A major open problem concerns the number of embeddings of such graphs, up to rigid motions, in Euclidean space. We capture embeddability by polynomial systems

Rigid body dynamics of mechanisms

CERN Document Server

Hahn, Hubert

2003-01-01

The second volume of Rigid Body Dynamics of Mechanisms covers applications via a systematic method for deriving model equations of planar and spatial mechanisms. The necessary theoretical foundations have been laid in the first volume that introduces the theoretical mechanical aspects of mechatronic systems. Here the focus is on the application of the modeling methodology to various examples of rigid-body mechanisms, simple planar ones as well as more challenging spatial problems. A rich variety of joint models, active constraints, plus active and passive force elements is treated. The book is intended for self-study by working engineers and students concerned with the control of mechanical systems, i.e. robotics, mechatronics, vehicles, and machine tools. The examples included are a likely source from which to choose models for university lectures.

Research Progress on Laser Cladding Amorphous Coatings on Metallic Substrates

Directory of Open Access Journals (Sweden)

CHEN Ming-hui

2017-01-01

Full Text Available The microstructure and property of amorphous alloy as well as the limitations of the traditional manufacturing methods for the bulk amorphous alloy were briefly introduced in this paper.Combined with characteristics of the laser cladding technique,the research status of the laser cladding Fe-based,Zr-based,Ni-based,Cu-based and Al-based amorphous coatings on the metal substrates were mainly summarized.The effects of factors such as laser processing parameter,micro-alloying element type and content and reinforcing phase on the laser cladding amorphous coatings were also involved.Finally,the main problems and the future research directions of the composition design and control of the laser-cladded amorphous coating,the design and optimization of the laser cladding process,and the basic theory of the laser cladding amorphous coatings were also put forward finally.

Amorphous silicon radiation detectors

Science.gov (United States)

Street, Robert A.; Perez-Mendez, Victor; Kaplan, Selig N.

1992-01-01

Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification.

The defects influence on domain wall propagation in bistable glass-coated microwires

International Nuclear Information System (INIS)

Rodionova, V.; Zhukova, V.; Ilyn, M.; Ipatov, M.; Perov, N.; Zhukov, A.

2012-01-01

We studied the domain wall (DW) dynamics of magnetically bistable amorphous glass-coated Fe 74 B 13 Si 11 C 2 microwires. In according to our experimental results magnetic field dependences of DW velocity of studied microwires can be divided into two groups: with uniform or uniformly accelerated DW propagation along the microwire. Strong correlation between the type of the magnetic field dependence of domain wall velocity, v(H), and the distribution of the local nucleation fields has been observed. Moreover, we observed abrupt increasing of DW velocity (jump) on the magnetic field dependences of the domain wall velocity, v(H), for the both types of the v(H) dependences. At the same time usual linear increasing of the domain wall velocity with magnetic field persists below these jumps. It was found that the jump height correlates with the location of nucleation place of the new domain wall. We have measured local nucleation field distribution in all the microwires. From local nucleation field distribution we have obtained the DW nucleation locations and estimated the jump height

The defects influence on domain wall propagation in bistable glass-coated microwires

Energy Technology Data Exchange (ETDEWEB)

Rodionova, V. [Magnetism Division, Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Immanuel Kant Baltic Federal University, Kaliningrad 236041 (Russian Federation); Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, San Sebastian 20018 (Spain); Zhukova, V., E-mail: valentina.zhukova@ehu.es [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, San Sebastian 20018 (Spain); Ilyn, M.; Ipatov, M. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, San Sebastian 20018 (Spain); Perov, N. [Magnetism Division, Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Zhukov, A. [Dpto. Fisica de Materiales, Fac. Quimicas, UPV/EHU, San Sebastian 20018 (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao 48011 (Spain)

2012-05-01

We studied the domain wall (DW) dynamics of magnetically bistable amorphous glass-coated Fe{sub 74}B{sub 13}Si{sub 11}C{sub 2} microwires. In according to our experimental results magnetic field dependences of DW velocity of studied microwires can be divided into two groups: with uniform or uniformly accelerated DW propagation along the microwire. Strong correlation between the type of the magnetic field dependence of domain wall velocity, v(H), and the distribution of the local nucleation fields has been observed. Moreover, we observed abrupt increasing of DW velocity (jump) on the magnetic field dependences of the domain wall velocity, v(H), for the both types of the v(H) dependences. At the same time usual linear increasing of the domain wall velocity with magnetic field persists below these jumps. It was found that the jump height correlates with the location of nucleation place of the new domain wall. We have measured local nucleation field distribution in all the microwires. From local nucleation field distribution we have obtained the DW nucleation locations and estimated the jump height.

Transformation processes during annealing of Al-amorphous alloys

International Nuclear Information System (INIS)

Petrescu, N.; Petrescu, M.; Calin, M.; Jianu, A.D.; Fecioru, M.

1993-01-01

As the amorphous aluminum alloys represent the newest achievement in rapid solidification of Al-based high strength heat resistent materials, a study was undertaken on the amorphous alloys in the Al-RE-TM system, the rare-earth metal being a lanthanide mixture and the transition metal a Ni-Fe substitution in definite proportions. The decomposition on heating of the most highly alloyed amorphous alloy in the investigated series is characterized by differential thermal analysis, electron microscopy and X-ray diffraction. (orig.)

Transformation processes during annealing of Al-amorphous alloys

Energy Technology Data Exchange (ETDEWEB)

Petrescu, N. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania)); Petrescu, M. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania)); Calin, M. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania)); Jianu, A.D. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania) IFTM-Bucharest (Romania)); Fecioru, M. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania) DACIA Enterprise-Bucharest (Romania))

1993-11-01

As the amorphous aluminum alloys represent the newest achievement in rapid solidification of Al-based high strength heat resistent materials, a study was undertaken on the amorphous alloys in the Al-RE-TM system, the rare-earth metal being a lanthanide mixture and the transition metal a Ni-Fe substitution in definite proportions. The decomposition on heating of the most highly alloyed amorphous alloy in the investigated series is characterized by differential thermal analysis, electron microscopy and X-ray diffraction. (orig.).

Amorphization of C-implanted Fe(Cr) alloys

International Nuclear Information System (INIS)

Knapp, J.A.; Follstaedt, D.M.; Sorensen, N.R.; Pope, L.E.

1991-01-01

The amorphous phase formed by implanting C into Fe alloyed with Cr, which is a prototype for the amorphous phase formed by implanting C into stainless steels, is compared to that formed by implanting C and Ti into Fe and steels. The composition range of the phase has been examined; higher Cr and C concentrations are required than needed with Ti and C. The friction and wear benefits obtained by implanting stainless steels with C only do not persist for the long durations and high wear loads found with Ti and C. However, the amorphous Fe-Cr-C alloys exhibit good aqueous corrosion resistance. (orig.)

Structure of a new dense amorphous ice

International Nuclear Information System (INIS)

Finney, J.L.; Bowron, D.T.; Soper, A.K.; Loerting, T.; Mayer, E.; Hallbrucker, A.

2002-01-01

The detailed structure of a new dense amorphous ice, VHDA, is determined by isotope substitution neutron diffraction. Its structure is characterized by a doubled occupancy of the stabilizing interstitial location that was found in high density amorphous ice, HDA. As would be expected for a thermally activated unlocking of the stabilizing 'interstitial', the transition from VHDA to LDA (low-density amorphous ice) is very sharp. Although its higher density makes VHDA a better candidate than HDA for a physical manifestation of the second putative liquid phase of water, as for the HDA case, the VHDA to LDA transition also appears to be kinetically controlled

Peculiarities of Vibration Characteristics of Amorphous Ices

Science.gov (United States)

Gets, Kirill V.; Subbotin, Oleg S.; Belosludov, Vladimir R.

2012-03-01

Dynamic properties of low (LDA), high (HDA) and very high (VHDA) density amorphous ices were investigated within the approach based on Lattice Dynamics simulations. In this approach, we assume that the short-range molecular order mainly determines the dynamic and thermodynamic properties of amorphous ices. Simulation cell of 512 water molecules with periodical boundary conditions and disordering allows us to study dynamical properties and dispersion curves in the Brillouin zone of pseudo-crystal. Existence of collective phenomena in amorphous ices which is usual for crystals but anomalous for disordered phase was confirmed in our simulations. Molecule amplitudes of delocalized (collective) as well as localized vibrations have been considered.

Deformation-driven diffusion and plastic flow in amorphous granular pillars.

Science.gov (United States)

Li, Wenbin; Rieser, Jennifer M; Liu, Andrea J; Durian, Douglas J; Li, Ju

2015-06-01

We report a combined experimental and simulation study of deformation-induced diffusion in compacted quasi-two-dimensional amorphous granular pillars, in which thermal fluctuations play a negligible role. The pillars, consisting of bidisperse cylindrical acetal plastic particles standing upright on a substrate, are deformed uniaxially and quasistatically by a rigid bar moving at a constant speed. The plastic flow and particle rearrangements in the pillars are characterized by computing the best-fit affine transformation strain and nonaffine displacement associated with each particle between two stages of deformation. The nonaffine displacement exhibits exponential crossover from ballistic to diffusive behavior with respect to the cumulative deviatoric strain, indicating that in athermal granular packings, the cumulative deviatoric strain plays the role of time in thermal systems and drives effective particle diffusion. We further study the size-dependent deformation of the granular pillars by simulation, and find that different-sized pillars follow self-similar shape evolution during deformation. In addition, the yield stress of the pillars increases linearly with pillar size. Formation of transient shear lines in the pillars during deformation becomes more evident as pillar size increases. The width of these elementary shear bands is about twice the diameter of a particle, and does not vary with pillar size.

Amorphization of thiamine chloride hydrochloride: A study of the crystallization inhibitor properties of different polymers in thiamine chloride hydrochloride amorphous solid dispersions.

Science.gov (United States)

Arioglu-Tuncil, Seda; Bhardwaj, Vivekanand; Taylor, Lynne S; Mauer, Lisa J

2017-09-01

Amorphous solid dispersions of thiamine chloride hydrochloride (THCl) were created using a variety of polymers with different physicochemical properties in order to investigate how effective the various polymers were as THCl crystallization inhibitors. THCl:polymer dispersions were prepared by lyophilizing solutions of THCl and amorphous polymers (guar gum, pectin, κ-carrageenan, gelatin, and polyvinylpyrrolidone (PVP)). These dispersions were stored at select temperature (25 and 40°C) and relative humidity (0, 23, 32, 54, 75, and 85% RH) conditions and monitored at different time points using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Moisture sorption isotherms of all samples were also obtained. Initially amorphous THCl was produced in the presence of ≥40% w/w pectin, κ-carrageenan, gelatin, and guar gum or ≥60% w/w PVP. Trends in polymer THCl crystallization inhibition (pectin≥κ-carrageenan>gelatin>guar gum≫PVP) were primarily based on the ability of the polymer to interact with THCl via hydrogen bonding and/or ionic interactions. The onset of THCl crystallization from the amorphous dispersions was also related to storage conditions. THCl remained amorphous at low RH conditions (0 and 23% RH) in all 1:1 dispersions except THCl:PVP. THCl crystallized in some dispersions below the glass transition temperature (T g ) but remained amorphous in others at T~T g . At high RHs (75 and 85% RH), THCl crystallized within one day in all samples. Given the ease of THCl amorphization in the presence of a variety of polymers, even at higher vitamin concentrations than would be found in foods, it is likely that THCl is amorphous in many low moisture foods. Copyright © 2017 Elsevier Ltd. All rights reserved.

Study of structural relaxation in amorphous alloys prepared by sputtering

International Nuclear Information System (INIS)

Habibi, S.; Banaee, N.; Majidy, S.

2004-01-01

Full text: We have prepared amorphous alloy of Al x Cu 1-x (with X= 93, 90, 80, 70, 30) using sputtering system. The rate of growth was 0.7 nm/sec. X-ray diffractometer was used to conform the amorphous nature of the prepared specimens. High temperature annealing can change amorphous to crystalline structure, while low temperature annealing may transform amorphous state to a more stable amorphous state via structural relaxation of the specimen and enhancing the properties of the alloys, such as mechanical ductility etc. Here we have annealed the alloys at temperatures 100, 150, 200, 250, 300 and 350 C for 1 hour. We observed that microhardness of the specimen increases with annealing and gets maximum value at 300 C. Our XRD experiments and also earlier Moessbauer studies show that while the average interatomic distances reduces due to annealing, structure remains amorphous

Amorphous silicon detectors in positron emission tomography

Energy Technology Data Exchange (ETDEWEB)

Conti, M. (Istituto Nazionale di Fisica Nucleare, Pisa (Italy) Lawrence Berkeley Lab., CA (USA)); Perez-Mendez, V. (Lawrence Berkeley Lab., CA (USA))

1989-12-01

The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters {epsilon}{sup 2}{tau}'s are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs.

Amorphous silicon detectors in positron emission tomography

International Nuclear Information System (INIS)

Conti, M.; Perez-Mendez, V.

1989-12-01

The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters ε 2 τ's are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs

Structural characterization of amorphous Fe-Si and its recrystallized layers

International Nuclear Information System (INIS)

Naito, Muneyuki; Ishimaru, Manabu; Hirotsu, Yoshihiko; Valdez, James A.; Sickafus, Kurt E.

2006-01-01

We have synthesized amorphous Fe-Si thin layers and investigated their microstructure using transmission electron microscopy (TEM). Si single crystals with (1 1 1) orientation were irradiated with 120 keV Fe + ions to a fluence of 4.0 x 10 17 cm -2 at cryogenic temperature (120 K), followed by thermal annealing at 1073 K for 2 h. A continuous amorphous layer with a bilayered structure was formed on the topmost layer of the Si substrate in the as-implanted specimen: the upper layer was an amorphous Fe-Si, while the lower one was an amorphous Si. After annealing, the amorphous bilayer crystallized into a continuous β-FeSi 2 thin layer

Excessively High Vapor Pressure of Al-based Amorphous Alloys

Directory of Open Access Journals (Sweden)

Jae Im Jeong

2015-10-01

Full Text Available Aluminum-based amorphous alloys exhibited an abnormally high vapor pressure at their approximate glass transition temperatures. The vapor pressure was confirmed by the formation of Al nanocrystallites from condensation, which was attributed to weight loss of the amorphous alloys. The amount of weight loss varied with the amorphous alloy compositions and was inversely proportional to their glass-forming ability. The vapor pressure of the amorphous alloys around 573 K was close to the vapor pressure of crystalline Al near its melting temperature, 873 K. Our results strongly suggest the possibility of fabricating nanocrystallites or thin films by evaporation at low temperatures.

Amorphization of metals by ion implantation and ion beam mixing

International Nuclear Information System (INIS)

Rauschenbach, B.; Heera, V.

1988-01-01

Amorphous metallic systems can be formed either by high-fluence ion implantation of glassforming species or by irradiation of layered metal systems with inert gas ions. Both techniques and experimental examples are presented. Empirical rules are discussed which predict whether a given system can be transformed into an amorphous phase. Influence of temperature, implantation dose and pre-existing crystalline metal composition on amorphization is considered. Examples are given of the implantation induced amorphous structure, recrystallization and formation of quasicrystalline structures. (author)

Associative memory through rigid origami

Science.gov (United States)

Murugan, Arvind; Brenner, Michael

2015-03-01

Mechanisms such as Miura Ori have proven useful in diverse contexts since they have only one degree of freedom that is easily controlled. We combine the theory of rigid origami and associative memory in frustrated neural networks to create structures that can ``learn'' multiple generic folding mechanisms and yet can be robustly controlled. We show that such rigid origami structures can ``recall'' a specific learned mechanism when induced by a physical impulse that only need resemble the desired mechanism (i.e. robust recall through association). Such associative memory in matter, seen before in self-assembly, arises due to a balance between local promiscuity (i.e., many local degrees of freedom) and global frustration which minimizes interference between different learned behaviors. Origami with associative memory can lead to a new class of deployable structures and kinetic architectures with multiple context-dependent behaviors.

Functionally rigid bistable [2]rotaxanes

DEFF Research Database (Denmark)

Nygaard, Sune; Leung, Ken C-F; Aprahamian, Ivan

2007-01-01

defines an unambiguous distance of 1.5 nm over which the ring moves between the MPTTF and NP units. The degenerate NP/NP [2]rotaxane was used to investigate the shuttling barrier by dynamic 1H NMR spectroscopy for the movement of the CBPQT4+ ring across the new rigid spacer. It is evident from...... better control over the position of the ring component in the ground state but also for control over the location of the CBPQT4+ ring during solution-state switching experiments, triggered either chemically (1H NMR) or electrochemically (cyclic voltammetry). In this instance, the use of the rigid spacer......Two-station [2]rotaxanes in the shape of a degenerate naphthalene (NP) shuttle and a nondegenerate monopyrrolotetrathiafulvalene (MPTTF)/NP redox-controllable switch have been synthesized and characterized in solution. Their dumbbell-shaped components are composed of polyether chains interrupted...

Phase Separation and Elastic Properties of Poly(Trimethylene Terephthalate-block-poly(Ethylene Oxide Copolymers

Directory of Open Access Journals (Sweden)

Elżbieta Piesowicz

2016-06-01

Full Text Available A series of poly(trimethylene terephthalate-block-poly(ethylene oxide (PTT-b-PEOT copolymers with different compositions of rigid PTT and flexible PEOT segments were synthesized via condensation in the melt. The influence of the block length and the block ratio on the micro-separated phase structure and elastic properties of the synthesized multiblock copolymers was studied. The PEOT segments in these copolymers were kept constant at 1130, 2130 or 3130 g/mol, whereas the PTT content varied from 30 up to 50 wt %. The phase separation was assessed using differential scanning calorimetry (DSC and dynamic mechanical thermal analysis (DMTA. The crystal structure of the synthesised block copolymers and their microstructure on the manometer scale was evaluated by using WAXS and SAXS analysis. Depending on the PTT/PEOT ratio, but also on the rigid and flexible segment length in PTT-b-PEO copolymers, four different domains were observed i.e.,: a crystalline PTT phase, a crystalline PEO phase (which exists for the whole series based on three types of PEOT segments, an amorphous PTT phase (only at 50 wt % content of PTT rigid segments and an amorphous PEO phase. Moreover, the elastic deformability and reversibility of PTT-b-PEOT block copolymers were studied during a cyclic tensile test. Determined values of permanent set resultant from maximum attained stain (100% and 200% for copolymers were used to evaluate their elastic properties.

Effects of clinically relevant MPL mutations in the transmembrane domain revealed at the atomic level through computational modeling.

Science.gov (United States)

Lee, Tai-Sung; Kantarjian, Hagop; Ma, Wanlong; Yeh, Chen-Hsiung; Giles, Francis; Albitar, Maher

2011-01-01

Mutations in the thrombopoietin receptor (MPL) may activate relevant pathways and lead to chronic myeloproliferative neoplasms (MPNs). The mechanisms of MPL activation remain elusive because of a lack of experimental structures. Modern computational biology techniques were utilized to explore the mechanisms of MPL protein activation due to various mutations. Transmembrane (TM) domain predictions, homology modeling, ab initio protein structure prediction, and molecular dynamics (MD) simulations were used to build structural dynamic models of wild-type and four clinically observed mutants of MPL. The simulation results suggest that S505 and W515 are important in keeping the TM domain in its correct position within the membrane. Mutations at either of these two positions cause movement of the TM domain, altering the conformation of the nearby intracellular domain in unexpected ways, and may cause the unwanted constitutive activation of MPL's kinase partner, JAK2. Our findings represent the first full-scale molecular dynamics simulations of the wild-type and clinically observed mutants of the MPL protein, a critical element of the MPL-JAK2-STAT signaling pathway. In contrast to usual explanations for the activation mechanism that are based on the relative translational movement between rigid domains of MPL, our results suggest that mutations within the TM region could result in conformational changes including tilt and rotation (azimuthal) angles along the membrane axis. Such changes may significantly alter the conformation of the adjacent and intrinsically flexible intracellular domain. Hence, caution should be exercised when interpreting experimental evidence based on rigid models of cytokine receptors or similar systems.

Rigid external maxillary distraction and rhinoplasty for pyknodysostosis.

Science.gov (United States)

Varol, Altan; Sabuncuoglu, Fidan Alakus; Sencimen, Metin; Akcam, Timur; Olmez, Hüseyin; Basa, Selçuk

2011-05-01

This article reports the treatment of an 33-year-old female patient with pyknodysostosis by rigid external distraction II midface distraction system. The patient with pyknodysostosis described in this report had severe midfacial hypoplasia. Correction of this by use of routine orthognathic surgery would require osteosynthesis and bone grafting. Risk of infection and/or nonunion after such a surgical procedure was considered too great, and therefore the possibility of treatment by distraction osteogenesis of the maxilla was evaluated. The rigid external distraction II midface distraction system was used to relocate the hypoplastic maxilla at anterior-inferior projection. Distraction osteogenesis should be considered as the primary reconstructive method for maxillofacial deformities in patients with sclerosing bone dysplasias, since this is the second reported case treated successfully with rigid external distraction.

Health hazards due to the inhalation of amorphous silica

Energy Technology Data Exchange (ETDEWEB)

Merget, R.; Bruening, T. [Research Institute for Occupational Medicine (BGFA), Bochum (Germany); Bauer, T. [Bergmannsheil, University Hospital, Department of Internal Medicine, Division of Pneumonology, Allergology and Sleep Medicine, Bochum (Germany); Kuepper, H.U.; Breitstadt, R. [Degussa-Huels Corp., Wesseling (Germany); Philippou, S. [Department of Pathology, Augusta Krankenanstalten, Bochum (Germany); Bauer, H.D. [Research Institute for Hazardous Substances (IGF), Bochum (Germany)

2002-01-01

Occupational exposure to crystalline silica dust is associated with an increased risk for pulmonary diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and lung cancer. This review summarizes the current knowledge about the health effects of amorphous (non-crystalline) forms of silica. The major problem in the assessment of health effects of amorphous silica is its contamination with crystalline silica. This applies particularly to well-documented pneumoconiosis among diatomaceous earth workers. Intentionally manufactured synthetic amorphous silicas are without contamination of crystalline silica. These synthetic forms may be classified as (1) wet process silica, (2) pyrogenic (''thermal'' or ''fumed'') silica, and (3) chemically or physically modified silica. According to the different physico-chemical properties, the major classes of synthetic amorphous silica are used in a variety of products, e.g. as fillers in the rubber industry, in tyre compounds, as free-flow and anti-caking agents in powder materials, and as liquid carriers, particularly in the manufacture of animal feed and agrochemicals; other uses are found in toothpaste additives, paints, silicon rubber, insulation material, liquid systems in coatings, adhesives, printing inks, plastisol car undercoats, and cosmetics. Animal inhalation studies with intentionally manufactured synthetic amorphous silica showed at least partially reversible inflammation, granuloma formation and emphysema, but no progressive fibrosis of the lungs. Epidemiological studies do not support the hypothesis that amorphous silicas have any relevant potential to induce fibrosis in workers with high occupational exposure to these substances, although one study disclosed four cases with silicosis among subjects exposed to apparently non-contaminated amorphous silica. Since the data have been limited, a risk of chronic bronchitis, COPD or

Health hazards due to the inhalation of amorphous silica

International Nuclear Information System (INIS)

Merget, R.; Bruening, T.; Bauer, T.; Kuepper, H.U.; Breitstadt, R.; Philippou, S.; Bauer, H.D.

2002-01-01

Occupational exposure to crystalline silica dust is associated with an increased risk for pulmonary diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and lung cancer. This review summarizes the current knowledge about the health effects of amorphous (non-crystalline) forms of silica. The major problem in the assessment of health effects of amorphous silica is its contamination with crystalline silica. This applies particularly to well-documented pneumoconiosis among diatomaceous earth workers. Intentionally manufactured synthetic amorphous silicas are without contamination of crystalline silica. These synthetic forms may be classified as (1) wet process silica, (2) pyrogenic (''thermal'' or ''fumed'') silica, and (3) chemically or physically modified silica. According to the different physico-chemical properties, the major classes of synthetic amorphous silica are used in a variety of products, e.g. as fillers in the rubber industry, in tyre compounds, as free-flow and anti-caking agents in powder materials, and as liquid carriers, particularly in the manufacture of animal feed and agrochemicals; other uses are found in toothpaste additives, paints, silicon rubber, insulation material, liquid systems in coatings, adhesives, printing inks, plastisol car undercoats, and cosmetics. Animal inhalation studies with intentionally manufactured synthetic amorphous silica showed at least partially reversible inflammation, granuloma formation and emphysema, but no progressive fibrosis of the lungs. Epidemiological studies do not support the hypothesis that amorphous silicas have any relevant potential to induce fibrosis in workers with high occupational exposure to these substances, although one study disclosed four cases with silicosis among subjects exposed to apparently non-contaminated amorphous silica. Since the data have been limited, a risk of chronic bronchitis, COPD or emphysema cannot be excluded. There is no

Amorphization, morphological instability and crystallization of krypton ion irradiated germanium

International Nuclear Information System (INIS)

Wang, L.M.; Birtcher, R.C.

1991-01-01

Krypton ion irradiation of crystalline Ge and subsequent thermal annealing were both carried out with in situ transmission electron microscopy observations. The temperature dependence of the amorphization dose, effect of foil thickness, morphological changes during continuous irradiation of the amorphous state as well as the effect of implanted gas have been determined. The dose of 1.5 MeV Kr required for amorphization increases with increasing temperature. At a fixed temperature, the amorphization dose is higher for thicker regions of the specimen. Continuous irradiation of amorphous Ge at room temperature results in a high density of small cavities which grow with increasing dose. Cavities do not coalesce during growth but develop into irregular-shaped holes that eventually transform the amorphous Ge into a sponge-like material. Formation of the spongy structure is independent of Kr implantation. The crystallization temperature and the morphology of recrystallized Ge depend on the Kr + dose. Voids are expelled from recrystallized Ge, while the sponge-like structure is retained after crystallization. (author)

Crystallization-induced plasticity of Cu-Zr containing bulk amorphous alloys

International Nuclear Information System (INIS)

Lee, Seok-Woo; Huh, Moo-Young; Fleury, Eric; Lee, Jae-Chul

2006-01-01

This study examined the parameter governing the plasticity observed in various Cu-Zr containing monolithic amorphous alloys. All the alloys were fully amorphous in their as-cast condition but exhibited different plastic strains. Microscopic observations of the quasi-statically compressed alloys showed abundant nanocrystallites in the amorphous matrices in the alloys that exhibited pronounced plasticity. On the other hand, insignificant changes in the microstructure were observed in the alloy that did not show plasticity. The mechanism for the formation of these deformation-induced nanocrystallites was examined from the viewpoints of thermodynamics and kinetics. The role of the deformation-induced nanocrystallites on the plasticity of the amorphous alloy was examined using high-resolution transmission electron microscopy. The results demonstrate that compressive loading facilitates nanocrystallization in monolithic Cu-Zr containing amorphous alloys, resulting in plasticity. The parameter governing the plasticity in these monolithic Cu-Zr containing amorphous alloys lies in the activation energy for the overall crystallization process

In situ observation of shear-driven amorphization in silicon crystals

Energy Technology Data Exchange (ETDEWEB)

He, Yang; Zhong, Li; Fan, Feifei; Wang, Chongmin; Zhu, Ting; Mao, Scott X.

2016-09-19

Amorphous materials have attracted great interest in the scientific and technological fields. An amorphous solid usually forms under the externally driven conditions of melt-quenching, irradiation and severe mechanical deformation. However, its dynamic formation process remains elusive. Here we report the in situ atomic-scale observation of dynamic amorphization processes during mechanical straining of nanoscale silicon crystals by high resolution transmission electron microscopy (HRTEM). We observe the shear-driven amorphization (SDA) occurring in a dominant shear band. The SDA involves a sequence of processes starting with the shear-induced diamond-cubic to diamond-hexagonal phase transition that is followed by dislocation nucleation and accumulation in the newly formed phase, leading to the formation of amorphous silicon. The SDA formation through diamond-hexagonal phase is rationalized by its structural conformity with the order in the paracrystalline amorphous silicon, which maybe widely applied to diamond-cubic materials. Besides, the activation of SDA is orientation-dependent through the competition between full dislocation nucleation and partial gliding.

The diagnostic role of thoracoscope in undiagnosed pleural effusion: Rigid versus flexible

Directory of Open Access Journals (Sweden)

Mostafa Mahmoud Abdel Mageid Shaheen

2014-07-01

Conclusions: Thoracoscopy using either fibreoptic bronchoscope or rigid thoracoscope is safe and well tolerated. Rigid thoracoscope has a higher diagnostic yield, easier handling, better orientation and is less expensive. Nevertheless, fibreoptic bronchoscope is an alternative technique if rigid thoracoscopy is not available.

Cooling rate effects on structure of amorphous graphene

International Nuclear Information System (INIS)

Van Hoang, Vo

2015-01-01

Simple monatomic amorphous 2D models with Honeycomb structure are obtained from 2D simple monatomic liquids with Honeycomb interaction potential (Rechtsman et al., Phys. Rev. Lett. 95, 228301 (2005)) via molecular dynamics (MD) simulations. Models are observed by cooling from the melt at various cooling rates. Temperature dependence of thermodynamic and structural properties including total energy, mean ring size, mean coordination number is studied in order to show evolution of structure and thermodynamics upon cooling from the melt. Structural properties of the amorphous Honeycomb structures are studied via radial distribution function (RDF), coordination number and ring distributions together with 2D visualization of the atomic configurations. Amorphous Honeycomb structures contain a large amount of structural defects including new ones which have not been previously reported yet. Cooling rate dependence of structural properties of the obtained amorphous Honeycomb structures is analyzed. Although amorphous graphene has been proposed theoretically and/or recently obtained by the experiments, our understanding of structural properties of the system is still poor. Therefore, our simulations highlight the situation and give deeper understanding of structure and thermodynamics of the glassy state of this novel 2D material

Investigations of metal contacts to amorphous evaporated Ge films and amorphous sputtered Si films

International Nuclear Information System (INIS)

Hafiz, M.; Mgbenu, E.; Tove, P.A.; Norde, H.; Petersson, S.

1976-02-01

Amorphous Ge or Si films have been used as ohmic contacts to high-resistivity n-silicon radiation detectors. One interesting property of this contact is that it does not inject minority carriers even when the depletion region extends up to the contact thus generating an extracting field there. The function of this contact is not yet fully explored. One part problem is the role of the metal films used as external contacts to the amorphous film. In this report the function of different contacting metals, such as Au, Al, Cr are investigated by measuring the I-V-characteristics of sandwich structures with two metals on both sides of the amorphous evaporated (Ge) and sputtered (Si) film (of typical thickness 1000 A). It was found that while the symmetric structures Au-αGe-Au and Cr-αGe-Cr were low-resistive (leading to resistivity values of approximately 10 5 Ωcm for the αGe film), Al-αGe-Al structures showed much higher resistance and were also polarity dependent. The former feature was found also for unsymmetric structures, i.e. Cr-αGe-Au, Cr-αGe-Al. (Auth.)

Correlation of atomic packing with the boson peak in amorphous alloys

Energy Technology Data Exchange (ETDEWEB)

Yang, W. M. [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Liu, H. S., E-mail: liuhaishun@126.com, E-mail: blshen@seu.edu.cn, E-mail: runweili@nimte.ac.cn, E-mail: jiangjz@zju.edu.cn; Zhao, Y. C. [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Liu, X. J. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Chen, G. X.; Man, Q. K.; Chang, C. T.; Li, R. W., E-mail: liuhaishun@126.com, E-mail: blshen@seu.edu.cn, E-mail: runweili@nimte.ac.cn, E-mail: jiangjz@zju.edu.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Dun, C. C. [Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27109 (United States); Shen, B. L., E-mail: liuhaishun@126.com, E-mail: blshen@seu.edu.cn, E-mail: runweili@nimte.ac.cn, E-mail: jiangjz@zju.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Inoue, A. [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); and others

2014-09-28

Boson peaks (BP) have been observed from phonon specific heats in 10 studied amorphous alloys. Two Einstein-type vibration modes were proposed in this work and all data can be fitted well. By measuring and analyzing local atomic structures of studied amorphous alloys and 56 reported amorphous alloys, it is found that (a) the BP originates from local harmonic vibration modes associated with the lengths of short-range order (SRO) and medium-range order (MRO) in amorphous alloys, and (b) the atomic packing in amorphous alloys follows a universal scaling law, i.e., the ratios of SRO and MRO lengths to solvent atomic diameter are 3 and 7, respectively, which exact match with length ratios of BP vibration frequencies to Debye frequency for the studied amorphous alloys. This finding provides a new perspective for atomic packing in amorphous materials, and has significant implications for quantitative description of the local atomic orders and understanding the structure-property relationship.

Distinct mechanisms of a phosphotyrosyl peptide binding to two SH2 domains.

Science.gov (United States)

Pang, Xiaodong; Zhou, Huan-Xiang

2014-05-01

Protein phosphorylation is very common post-translational modification, catalyzed by kinases, for signaling and regulation. Phosphotyrosines frequently target SH2 domains. The spleen tyrosine kinase (Syk) is critical for tyrosine phosphorylation of multiple proteins and for regulation of important pathways. Phosphorylation of both Y342 and Y346 in Syk linker B is required for optimal signaling. The SH2 domains of Vav1 and PLC-γ both bind this doubly phosphorylated motif. Here we used a recently developed method to calculate the effects of Y342 and Y346 phosphorylation on the rate constants of a peptide from Syk linker B binding to the SH2 domains of Vav1 and PLC-γ. The predicted effects agree well with experimental observations. Moreover, we found that the same doubly phosphorylated peptide binds the two SH2 domains via distinct mechanisms, with apparent rigid docking for Vav1 SH2 and dock-and-coalesce for PLC-γ SH2.

Rigid origami vertices: conditions and forcing sets

Directory of Open Access Journals (Sweden)

Zachary Abel

2016-04-01

Full Text Available We develop an intrinsic necessary and sufficient condition for single-vertex origami crease patterns to be able to fold rigidly.  We classify such patterns in the case where the creases are pre-assigned to be mountains and valleys as well as in the unassigned case.  We also illustrate the utility of this result by applying it to the new concept of minimal forcing sets for rigid origami models, which are the smallest collection of creases that, when folded, will force all the other creases to fold in a prescribed way.

Type number and rigidity of fibred surfaces

International Nuclear Information System (INIS)

Markov, P E

2001-01-01

Infinitesimal l-th order bendings, 1≤l≤∞, of higher-dimensional surfaces are considered in higher-dimensional flat spaces (for l=∞ an infinitesimal bending is assumed to be an analytic bending). In terms of the Allendoerfer type number, criteria are established for the (r,l)-rigidity (in the terminology of Sabitov) of such surfaces. In particular, an (r,l)-infinitesimal analogue is proved of the classical theorem of Allendoerfer on the unbendability of surfaces with type number ≥3 and the class of (r,l)-rigid fibred surfaces is distinguished

Evaluating a method for automated rigid registration

DEFF Research Database (Denmark)

Darkner, Sune; Vester-Christensen, Martin; Larsen, Rasmus

2007-01-01

to point distance. T-test for common mean are used to determine the performance of the two methods (supported by a Wilcoxon signed rank test). The performance influence of sampling density, sampling quantity, and norms is analyzed using a similar method.......We evaluate a novel method for fully automated rigid registration of 2D manifolds in 3D space based on distance maps, the Gibbs sampler and Iterated Conditional Modes (ICM). The method is tested against the ICP considered as the gold standard for automated rigid registration. Furthermore...

Relaxation processes during amorphous metal alloys heating

International Nuclear Information System (INIS)

Malinochka, E.Ya.; Durachenko, A.M.; Borisov, V.T.

1982-01-01

Behaviour of Te+15 at.%Ge and Fe+13 at.%P+7 at.%C amorphous metal alloys during heating has been studied using the method of differential scanning calorimetry (DSC) as the most convenient one for determination of the value of heat effects, activation energies, temperature ranges of relaxation processes. Thermal effects corresponding to high-temperature relaxation processes taking place during amorphous metal alloys (AMA) heating are detected. The change of ratio of relaxation peaks values on DSC curves as a result of AMA heat treatment can be explained by the presence of a number of levels of inner energy in amorphous system, separated with potential barriers, the heights of which correspond to certain activation energies of relaxation processes

Lithium adsorption on amorphous aluminum hydroxides and gibbsite

OpenAIRE

Prodromou, Konstantinos P.

2016-01-01

Lithium (Li) adsorption on both amorphous aluminum hydroxides and gibbsite was studied. For the amorphous Al(OH)3 the adsorption was found to be pH dependent. Generally, 1.6 times more Li was adsorbed at initial pH value 8.0 compared with pH value 6.50. Gibbsite adsorbed 11.6 to 45.5 times less Li quantities compared with amorphous Al(OH)3. Lithium adsorption was not depended on equilibrium times. It remained stable for all equilibrium times used. Lithium quantities extracted with 1N CH3COONH...

Development of shear bands in amorphous-crystalline metallic alloys

International Nuclear Information System (INIS)

Pozdnyakov, V.A.

2004-01-01

A theoretical study is made into conditions of shear band evolution in amorphous-crystalline alloys with various morphological types of structural constituents. The condition of shear band evolution in thin amorphous alloys in the interior of the crystalline matrix is obtained. It is shown that a scale effect exists which manifests itself in suppression of the process of localized plastic flow with amorphous alloy thickness decreasing down to the limit. The analysis of the condition for shear band evolution in an amorphous alloy with nanocrystalline inclusions is accomplished. The relationship of a critical stress of shear band evolution to a volume fraction of disperse crystal inclusions is obtained. A consideration is also given to the evolution of shear bands in the material containing amorphous and crystalline areas of micro meter size. For the alloy with the structure of this type conditions for propagation of localized flows by a relay race type mechanism are determined [ru

Analytical theory of noncollinear amorphous metallic magnetism

International Nuclear Information System (INIS)

Kakehashi, Y.; Uchida, T.

2001-01-01

Analytical theory of noncollinear magnetism in amorphous metals is proposed on the basis of the Gaussian model for the distribution of the interatomic distance and the saddle-point approximation. The theory removes the numerical difficulty in the previous theory based on the Monte-Carlo sampling method, and reasonably describes the magnetic properties of amorphous transition metals

Lateral rigidity of cracked concrete structures

International Nuclear Information System (INIS)

Castellani, A.; Chesi, C.

1979-01-01

Numerical results are discussed on the lateral rigidity of reinforced concrete structures with a given crack distribution. They have been favourably checked with experimental results for cylindrical shells under the effect of a thermal gradient producing vertical cracking or vertical plus horizontal cracking. The main effects characterizing the concrete behaviour are: (1) The shear transfer across a crack; (2) The shear transfer degradation after cyclic loading; (3) The tension stiffening provided by the concrete between crack and crack, in the normal stress transfer; (4) The temperature effect on the elastic moduli of concrete, when cracks are of thermal origin. Only the 1st effect is discussed on an experimental basis. Two broad cathegories of reinforced concrete structures have been investigated in this respect: shear walls of buildings and cylindrical containment structures. The main conclusions so far reached are: (1) Vertical cracks are unlikely to decrease the lateral rigidity to less than 80% of the original one, and to less than 90% when they do not involve the entire thickness of the wall; (2) The appearence of horizontal cracks can reduce the lateral rigidity by some 30% or more; (3) A noticeable but not yet evaluated influence is shown by cyclic loading. (orig.)

Amorphization Mechanism of Icosahedral Platinum Clusters

International Nuclear Information System (INIS)

Apra, Edoardo; Baletto, Francesca; Ferrando, Riccardo; Fortunelli, Alessandro

2004-01-01

The amorphization mechanism of high-symmetry pt nanoclusters is investigated by a combination of Molecular Dynamics simulations and Density Functional calculations. A general mechanism for amorphization, involving rosette-like structural transformations at fivefold vertices, is proposed. IN the tosette, a fivefold vertex is transformed into a hexagonal ring. We show that for icosahedral Pt nanoclusters, this transformation is associated with an energy gain, so that their most favorable structures have a low symmetry even at icosahedral magic numbers

Novel Amorphous Fe-Zr-Si(Cu) Boron-free Alloys

Science.gov (United States)

Kopcewicz, M.; Grabias, A.; Latuch, J.; Kowalczyk, M.

2010-07-01

Novel amorphous Fe80(ZrxSi20-x-y)Cuy boron-free alloys, in which boron was completely replaced by silicon as a glass forming element, have been prepared in the form of ribbons by a melt quenching technique. The X-ray diffraction and Mössbauer spectroscopy measurements revealed that the as-quenched ribbons with the composition of x = 6-10 at. % and y = 0, 1 at. % are predominantly amorphous. DSC measurements allowed the estimation of the crystallization temperatures of the amorphous alloys. The soft magnetic properties have been studied by the specialized rf-Mössbauer technique in which the spectra were recorded during an exposure of the samples to the rf field of 0 to 20 Oe at 61.8 MHz. Since the rf-collapse effect observed is very sensitive to the local anisotropy fields it was possible to evaluate the soft magnetic properties of amorphous alloys studied. The rf-Mössbauer studies were accompanied by the conventional measurements of the quasi-static hysteresis loops from which the magnetization and coercive fields were estimated. It was found that amorphous Fe-Zr-Si(Cu) alloys are magnetically very soft, comparable with those of the conventional amorphous B-containing Fe-based alloys.

Connections rigidity effect on probability of fracture in steel moment frames

Directory of Open Access Journals (Sweden)

Gholamreza Abdollahzadeh

2017-08-01

Full Text Available Connections in steel moment frames are idealized in full pinned and full rigid conditions. Because with this assumption, in spite of real behavior of connection, real story drifts are less anticipated and maybe frame is designed without performance of bracing. There are several methods for modeling actual behavior of semi rigid connections. In this method a connection with certain rigidity is modeled by a rotational spring with corresponding stiffness. This stiffness is achieved by certain formula. In other words, each percent of rigidity corresponds to one rotational spring stiffness. In this research in order to evaluate the real behavior of connection in analysis and designing process and fracture probability one frame including four stories and one bay with three types of connection has been modeled and designed in ETABS. Each model has an individual rigidity which is equal to 10, 75 and 90 percent. With respect to maximum drift and different PGA in roof, probabilities of low, medium, high and complete fracture were calculated. For this purpose, with applying different PGA to modeled frames, amounts of drift in the roof are achieved. Then these values are compared with given values in American code. Finally, investigation showed that when rigidity in frame connections increases, the probability of frame fracture decreases. In other words, fully rigid assumption of connection in analysis process leads to decreasing in real probability of fracture in frames which is a noticeable risk in building designing processes.

Rigid-plastic seismic design of reinforced concrete structures

DEFF Research Database (Denmark)

Costa, Joao Domingues; Bento, R.; Levtchitch, V.

2007-01-01

structural strength with respect to a pre-defined performance parameter using a rigid-plastic response spectrum, which is characteristic of the ground motion alone. The maximum strength demand at any point is solely dependent on the intensity of the ground motion, which facilitates the task of distributing......In this paper a new seismic design procedure for Reinforced Concrete (R/C) structures is proposed-the Rigid-Plastic Seismic Design (RPSD) method. This is a design procedure based on Non-Linear Time-History Analysis (NLTHA) for systems expected to perform in the non-linear range during a lifetime...... earthquake event. The theoretical background is the Theory of Plasticity (Rigid-Plastic Structures). Firstly, a collapse mechanism is chosen and the corresponding stress field is made safe outside the regions where plastic behaviour takes place. It is shown that this allows the determination of the required...

Unified Creep Plasticity Damage (UCPD) Model for Rigid Polyurethane Foams.

Energy Technology Data Exchange (ETDEWEB)

Neilsen, Michael K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Scherzinger, William M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hinnerichs, Terry D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lo, Chi S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-06-01

Numerous experiments were performed to characterize the mechanical response of several different rigid polyurethane foams (FR3712, PMDI10, PMDI20, and TufFoam35) to large deformation. In these experiments, the effects of load path, loading rate, and temperature were investigated. Results from these experiments indicated that rigid polyurethane foams exhibit significant volumetric and deviatoric plasticity when they are compressed. Rigid polyurethane foams were also found to be very strain-rate and temperature dependent. These foams are also rather brittle and crack when loaded to small strains in tension or to larger strains in compression. Thus, a new Unified Creep Plasticity Damage (UCPD) model was developed and implemented into SIERRA with the name Foam Damage to describe the mechanical response of these foams to large deformation at a variety of temperatures and strain rates. This report includes a description of recent experiments and experimental findings. Next, development of a UCPD model for rigid, polyurethane foams is described. Selection of material parameters for a variety of rigid polyurethane foams is then discussed and finite element simulations with the new UCPD model are compared with experimental results to show behavior that can be captured with this model.

Ductile fracture surface morphology of amorphous metallic alloys

NARCIS (Netherlands)

Miskuf, J; Csach, K; Ocelik, [No Value; Bengus, VZ; Tabachnikova, ED; Duhaj, P; Ocelik, Vaclav

1999-01-01

Fracture surfaces of ductile failure of two types bulk amorphous metallic alloys were studied using quantitative and qualitative fractographic analysis. The observed fractographic behaviour of ductile failure in comparison with the ductile failure of amorphous alloy ribbons shows signs of the same

Elasticity of Relativistic Rigid Bodies?

Science.gov (United States)

Smarandache, Florentin

2013-10-01

In the classical Twin Paradox, according to the Special Theory of Relativity, when the traveling twin blasts off from the Earth to a relative velocity v =√{/3 } 2 c with respect to the Earth, his measuring stick and other physical objects in the direction of relative motion shrink to half their lengths. How is that possible in the real physical world to have let's say a rigid rocket shrinking to half and then later elongated back to normal as an elastic material when it stops? What is the explanation for the traveler's measuring stick and other physical objects, in effect, return to the same length to their original length in the Stay-At-Home, but there is no record of their having shrunk? If it's a rigid (not elastic) object, how can it shrink and then elongate back to normal? It might get broken in such situation.

On flexible and rigid nouns

DEFF Research Database (Denmark)

Rijkhoff, Jan

2008-01-01

Studies in Language 32-3 (2008), 727-752. Special issue: Parts of Speech: Descriptive tools, theoretical constructs Jan Rijkhoff - On flexible and rigid nouns This article argues that in addition to the flexible lexical categories in Hengeveld’s classification of parts-of-speech systems (Contentive......, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members of flexible word classes are characterized by their vague semantics, which in the case of nouns means that values for the semantic features Shape...... and Homogeneity are either left undetermined or they are specified in such a way that they do not quite match the properties of the kind of entity denoted by the flexible item in the external world. I will then argue that flexible word classes constitute a proper category (i.e. they are not the result of a merger...

Rigidity spectrum of Forbush decrease

International Nuclear Information System (INIS)

Sakakibara, S.; Munakata, K.; Nagashima, K.

1985-01-01

Using data from neutron monitors and muon telescopes at surface and underground stations, the average rigidity spectrum of Forbush decreases (Fds) during the period of 1978-1982 were obtained. Thirty eight Ed-events are classified into two groups, Hard Fd and Soft FD according to size of Fd at the Sakashita station. It is found that a spectral form of a fractional-power type (P to the-gamma sub 1 (P+P sub c) to the -gamma sub2) is more suitable than that of a power-exponential type or of a power type with an upper limiting rigidity. The best fitted spectrum of the fractional-power type is expressed by gamma sub1 = 0.37, gamma sub2 = 0.89 and P subc = 10 GV for Hard Fd and gamma sub1 = 0.77, gamma sub2 = 1.02 and P sub c - 14GV for Soft Fd

On the study of the magnetic domain pattern via the initial magnetization curve

International Nuclear Information System (INIS)

Wu, T.

1997-01-01

This study inquires into the relationships between the initial magnetization curve and the magnetic domain pattern in the demagnetized states for amorphous TbFeCo as well as multilayered Co/Pd thin film samples. This was done specifically through an investigation of different demagnetized states of samples demagnetized by a variety of methods. The magnetic domain pattern for the sample demagnetized by an in-plane magnetic field and for the sample demagnetized by a perpendicular magnetic field was found to be quite different even though both states have zero magnetization. The former state has denser and finer domains than the latter. In addition, both states were studied in light of the initial magnetization curves obtained by measurements of the magneto-optic Kerr effect and the extraordinary Hall effect. Moreover, the initial magnetization for the fine domains increases with an increase in magnetic field, while for the coarse domains, the initial magnetization remains at zero for magnetic field below coercivity H c , then rises sharply to saturated magnetization when magnetic field is nearly equal to H c . copyright 1997 American Institute of Physics

An evaluation of canonical forms for non-rigid 3D shape retrieval

OpenAIRE

Pickup, David; Liu, Juncheng; Sun, Xianfang; Rosin, Paul L.; Martin, Ralph R.; Cheng, Zhiquan; Lian, Zhouhui; Nie, Sipin; Jin, Longcun; Shamai, Gil; Sahillioğlu, Yusuf; Kavan, Ladislav

2018-01-01

Canonical forms attempt to factor out a non-rigid shape’s pose, giving a pose-neutral shape. This opens up the\\ud possibility of using methods originally designed for rigid shape retrieval for the task of non-rigid shape retrieval.\\ud We extend our recent benchmark for testing canonical form algorithms. Our new benchmark is used to evaluate a\\ud greater number of state-of-the-art canonical forms, on five recent non-rigid retrieval datasets, within two different\\ud retrieval frameworks. A tota...

Blast wave interaction with a rigid surface

International Nuclear Information System (INIS)

Josey, T.; Whitehouse, D.R.; Ripley, R.C.; Dionne, J.P.

2004-01-01

A simple model used to investigate blast wave interactions with a rigid surface is presented. The model uses a constant volume energy source analogue to predict pressure histories at gauges located directly above the charge. A series of two-dimensional axi-symmetric CFD calculations were performed, varying the height of the charge relative to the ground. Pressure histories, along with isopycnic plots are presented to evaluate the effects of placing a charge in close proximity to a rigid surface. When a charge is placed near a solid surface the pressure histories experienced at gauges above the charge indicate the presence of two distinct pressure peaks. The first peak is caused by the primary shock and the second peak is a result of the wave reflections from the rigid surface. As the distance from the charge to the wall is increased the magnitude of the second pressure peak is reduced, provided that the distance between the charge and the gauge is maintained constant. The simple model presented is able to capture significant, predictable flow features. (author)

Hydrodynamics of a flexible plate between pitching rigid plates

Science.gov (United States)

Kim, Junyoung; Kim, Daegyoum

2017-11-01

The dynamics of a flexible plate have been studied as a model problem in swimming and flying of animals and fluid-structure interaction of plants and flags. Motivated by fish schooling and an array of sea grasses, we investigate the dynamics of a flexible plate closely placed between two pitching rigid plates. In most studies on passive deformation of the flexible plate, the plate is immersed in a uniform flow or a wavy flow. However, in this study, the flexible plate experiences periodic deformation by the oscillatory flow generated by the prescribed pitching motion of the rigid plates. In our model, the pitching axes of the rigid plates and the clamping position of the flexible plate are aligned on the same line. The flexible plate shows various responses depending on length and pitching frequency of rigid plates, thickness of a flexible plate, and free-stream velocity. To find the effect of each variable on the response of the flexible plate, amplitude of a trailing edge and modal contribution of a flapping motion are compared, and flow structure around the flexible plate is examined.

A wearable microwave antenna array for time-domain breast tumor screening

OpenAIRE

Porter, Emily; Bahrami, Hadi; Santorelli, Adam; Gosselin, Benoit; Rusch, Leslie; Popovic, Milica

2016-01-01

In this work, we present a clinical prototype with a wearable patient interface for microwave breast cancer detection. The long-term aim of the prototype is a breast health monitoring application. The system operates using multistatic time-domain pulsed radar, with 16 flexible antennas embedded into a bra. Unlike the previously reported, table-based prototype with a rigid cup-like holder, the wearable one requires no immersion medium and enables simple localization of breast surface. In compa...

Amorphization and the effect of implanted ions in SiC

International Nuclear Information System (INIS)

Snead, L.L.; Zinkle, S.J.

1994-01-01

The effects of implanted ion chemistry and displacement damage on the amorphization threshold dose of SiC were studied using cross-section transmission electron microscopy. Room temperature as well as 200 and 400 C irradiations were carried out with 3.6 MeV Fe, 1.8 MeV Cl, 1 MeV He or 0.56 MeV Si ions. The room temperature amorphization threshold dose in irradiated regions well separated from the implanted ions was found to range from 0.3 to 0.5 dpa for the four different ion species. The threshold dose for amorphization in the He, Si and Fe ion-implanted regions was also ∼0.3 to 0.5 dpa. On the other hand, the amorphization threshold in the Cl-implanted region was only about 0.1 dpa. The volume change associated with amorphization was ∼17%. No evidence for amorphization was obtained in specimens irradiated at 200 or 400 C. An understanding of the microstructural evolution of SiC under irradiation is critical to the application of these materials in fusion energy systems

Unipolar time-differential charge sensing in non-dispersive amorphous solids

International Nuclear Information System (INIS)

Goldan, A. H.; Rowlands, J. A.; Tousignant, O.; Karim, K. S.

2013-01-01

The use of high resistivity amorphous solids as photodetectors, especially amorphous selenium, is currently of great interest because they are readily produced over large area at substantially lower cost compared to grown crystalline solids. However, amorphous solids have been ruled out as viable radiation detection media for high frame-rate applications, such as single-photon-counting imaging, because of low carrier mobilities, transit-time-limited photoresponse, and consequently, poor time resolution. To circumvent the problem of poor charge transport in amorphous solids, we propose unipolar time-differential charge sensing by establishing a strong near-field effect using an electrostatic shield within the material. For the first time, we have fabricated a true Frisch grid inside a solid-state detector by evaporating amorphous selenium over photolithographically prepared multi-well substrates. The fabricated devices are characterized with optical, x-ray, and gamma-ray impulse-like excitations. Results prove the proposed unipolar time-differential property and show that time resolution in non-dispersive amorphous solids can be improved substantially to reach the theoretical limit set by spatial spreading of the collected Gaussian carrier cloud.

Atomistic modeling of defect evolution in Si for amorphizing and subamorphizing implants

International Nuclear Information System (INIS)

Lopez, Pedro; Pelaz, Lourdes; Marques, Luis A.; Santos, Ivan; Aboy, Maria; Barbolla, Juan

2004-01-01

Solid phase epitaxial regrowth of pre-amorphizing implants has received significant attention as a method to achieve high dopant activation with minimal diffusion at low implant temperatures and suppress channelling. Therefore, a good understanding of the amorphization and regrowth mechanisms is required in process simulators. We present an atomistic amorphization and recrystallization model that uses the interstitial-vacancy (I-V) pair as a building block to describe the amorphous phase. I-V pairs are locally characterized by the number of neighbouring I-V pairs. This feature captures the damage generation and the dynamical annealing during ion implantation, and also explains the annealing behaviour of amorphous layers and amorphous pockets

Molecular Mechanics of the α-Actinin Rod Domain: Bending, Torsional, and Extensional Behavior

Science.gov (United States)

Golji, Javad; Collins, Robert; Mofrad, Mohammad R. K.

2009-01-01

α-Actinin is an actin crosslinking molecule that can serve as a scaffold and maintain dynamic actin filament networks. As a crosslinker in the stressed cytoskeleton, α-actinin can retain conformation, function, and strength. α-Actinin has an actin binding domain and a calmodulin homology domain separated by a long rod domain. Using molecular dynamics and normal mode analysis, we suggest that the α-actinin rod domain has flexible terminal regions which can twist and extend under mechanical stress, yet has a highly rigid interior region stabilized by aromatic packing within each spectrin repeat, by electrostatic interactions between the spectrin repeats, and by strong salt bridges between its two anti-parallel monomers. By exploring the natural vibrations of the α-actinin rod domain and by conducting bending molecular dynamics simulations we also predict that bending of the rod domain is possible with minimal force. We introduce computational methods for analyzing the torsional strain of molecules using rotating constraints. Molecular dynamics extension of the α-actinin rod is also performed, demonstrating transduction of the unfolding forces across salt bridges to the associated monomer of the α-actinin rod domain. PMID:19436721

Self-consistent modeling of amorphous silicon devices

International Nuclear Information System (INIS)

Hack, M.

1987-01-01

The authors developed a computer model to describe the steady-state behaviour of a range of amorphous silicon devices. It is based on the complete set of transport equations and takes into account the important role played by the continuous distribution of localized states in the mobility gap of amorphous silicon. Using one set of parameters they have been able to self-consistently simulate the current-voltage characteristics of p-i-n (or n-i-p) solar cells under illumination, the dark behaviour of field-effect transistors, p-i-n diodes and n-i-n diodes in both the ohmic and space charge limited regimes. This model also describes the steady-state photoconductivity of amorphous silicon, in particular, its dependence on temperature, doping and illumination intensity

Fabrication and application of amorphous semiconductor devices

International Nuclear Information System (INIS)

Kumurdjian, Pierre.

1976-01-01

This invention concerns the design and manufacture of elecric switching or memorisation components with amorphous semiconductors. As is known some compounds, particularly the chalcogenides, have a resistivity of the semiconductor type in the amorphous solid state. These materials are obtained by the high temperature homogeneisation of several single elements such as tellurium, arsenic, germanium and sulphur, followed by water or air quenching. In particular these compounds have useful switching and memorisation properties. In particular they have the characteristic of not suffering deterioration when placed in an environment subjected to nuclear radiations. In order to know more about the nature and properties of these amorphous semiconductors the French patent No. 71 28048 of 30 June 1971 may be consulted with advantage [fr

21. Colloquium on metallurgy. Amorphous alloys and materials

International Nuclear Information System (INIS)

1979-01-01

Twenty-two papers were presented at the 21st colloquium on metallurgy of amorphous alloys and materials. They deal with the applications, the various types, the preparation methods, the structure, the magnetic and thermodynamic properties and the structure defects of the amorphous materials [fr

Surface impedance tensor in amorphous wires with helical anisotropy: Magnetic hysteresis and asymmetry

International Nuclear Information System (INIS)

Makhnovskiy, D. P.; Panina, L. V.; Mapps, D. J.

2001-01-01

This article concerns the investigation of the magnetic behavior of the surface impedance tensor cflx var-sigma in CoSiB amorphous wires having a residual torsion stress and a helical anisotropy. The full tensor cflx var-sigma involving three different components is found by measuring the S 21 parameter at a required excitation with a Hewlett-Packard network/spectrum analyzer at MHz frequencies. In general, the impedance plots versus axial magnetic field H ex exhibit a hysteresis related to that for the case of static magnetization. The diagonal components of cflx var-sigma (longitudinal var-sigma zz and circular var-sigma v ar-phi v ar-phi) show a sharp peak in a narrow field interval where the domain walls form and contribute to the ac magnetization dynamics. This peak is not seen for the off-diagonal component var-sigma zv ar-phi (var-sigma v ar-phi z ) since the existence of the domain structure suppresses it. Applying a dc bias current results in a gradual transition to a nonhysteretic asymmetrical behavior with an enhanced sensitivity. The portions of the experimental plots associated with the rotational dynamic process are in qualitative agreement with the theory based on a single-domain model. [copyright] 2001 American Institute of Physics

The nature of the photoluminescence in amorphized PZT

International Nuclear Information System (INIS)

Silva, M.S.; Cilense, M.; Orhan, E.; Goes, M.S.; Machado, M.A.C.; Santos, L.P.S.; Paiva-Santos, C.O.; Longo, E.; Varela, J.A.; Zaghete, M.A.; Pizani, P.S.

2005-01-01

The polymeric precursor method was used to synthesize lead zirconate titanate powder (PZT). The crystalline powder was then amorphized by a high-energy ball milling process during 120 h. A strong photoluminescence emission was observed at room temperature for the amorphized PZT powder. The powders were characterized by XRD and the percentage of amorphous phase was calculated through Rietveld refinement. The microstructure for both phases was investigated by TEM. The optical gap was calculated through the Wood and Tauc method using the UV-Vis. data. Quantum mechanical calculations were carried out to give an interpretation of the photoluminescence in terms of electronic structure

Amorphous photonic crystals with only short-range order.

Science.gov (United States)

Shi, Lei; Zhang, Yafeng; Dong, Biqin; Zhan, Tianrong; Liu, Xiaohan; Zi, Jian

2013-10-04

Distinct from conventional photonic crystals with both short- and long-range order, amorphous photonic crystals that possess only short-range order show interesting optical responses owing to their unique structural features. Amorphous photonic crystals exhibit unique light scattering and transport, which lead to a variety of interesting phenomena such as isotropic photonic bandgaps or pseudogaps, noniridescent structural colors, and light localization. Recent experimental and theoretical advances in the study of amorphous photonic crystals are summarized, focusing on their unique optical properties, artificial fabrication, bionspiration, and potential applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of tensile stress and frequency on the longitudinal magnetic hysteresis of amorphous wires

International Nuclear Information System (INIS)

Torres, Carlos; Maria Munoz, Jose; Hernandez-Gomez, Pablo; Francisco, Carlos de

2010-01-01

This work studies the longitudinal magnetic hysteresis of amorphous wires with different Fe or Co compositions through an external magnetic field in the axial direction. Measurements have been carried out with the help of a digitally processed system in the 50 Hz-1 kHz frequency range. In addition, the influence of different tensile stresses has been also analyzed. The results show that both parameters change considerably the magnetic hysteresis of the wires but in a different way depending on their composition. This behaviour has been interpreted in terms of the different domain distribution associated with the opposite sign of the magnetostriction for Fe and Co-based wires, respectively.

A Magnetic Sensor with Amorphous Wire

Directory of Open Access Journals (Sweden)

Dongfeng He

2014-06-01

Full Text Available Using a FeCoSiB amorphous wire and a coil wrapped around it, we have developed a sensitive magnetic sensor. When a 5 mm long amorphous wire with the diameter of 0.1 mm was used, the magnetic field noise spectrum of the sensor was about 30 pT/ÖHz above 30 Hz. To show the sensitivity and the spatial resolution, the magnetic field of a thousand Japanese yen was scanned with the magnetic sensor.

Glass transition and intermixing of amorphous water and methanol

International Nuclear Information System (INIS)

Souda, Ryutaro

2004-01-01

The diffusion of molecules in amorphous water and methanol films has been investigated on the basis of time-of-flight secondary ion mass spectrometry as a function of temperature. The glass-liquid transition of the amorphous water film occurs at 130-145 K as confirmed from the surface segregation of embedded methanol molecules. The morphology of the pure amorphous water film changes drastically at 160 K as a consequence of dewetting induced by the surface tension and the strongly decreased viscosity of the film. The morphology of the amorphous methanol film changes at 115 K following the self-diffusion onset at 80 K. The binary films of water and heavy methanol are intermixed completely at 136 K as evidenced by the occurrence of the H/D exchange

Rigidity of the magic pentagram game

Science.gov (United States)

Kalev, Amir; Miller, Carl A.

2018-01-01

A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.

Rigidity of the magic pentagram game.

Science.gov (United States)

Kalev, Amir; Miller, Carl A

2018-01-01

A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.

Elastic properties of rigid fiber-reinforced composites

Science.gov (United States)

Chen, J.; Thorpe, M. F.; Davis, L. C.

1995-05-01

We study the elastic properties of rigid fiber-reinforced composites with perfect bonding between fibers and matrix, and also with sliding boundary conditions. In the dilute region, there exists an exact analytical solution. Around the rigidity threshold we find the elastic moduli and Poisson's ratio by decomposing the deformation into a compression mode and a rotation mode. For perfect bonding, both modes are important, whereas only the compression mode is operative for sliding boundary conditions. We employ the digital-image-based method and a finite element analysis to perform computer simulations which confirm our analytical predictions.

Fast and non-destructive pore structure analysis using terahertz time-domain spectroscopy.

OpenAIRE

Markl, Daniel; Bawuah, Prince; Ridgway, Cathy; van den Ban, Sander; Goodwin, Daniel J; Ketolainen, Jarkko; Gane, Patrick; Peiponen, Kai-Erik; Zeitler, Jochen Axel

2018-01-01

Pharmaceutical tablets are typically manufactured by the uni-axial compaction of powder that is confined radially by a rigid die. The directional nature of the compaction process yields not only anisotropic mechanical properties (e.g. tensile strength) but also directional properties of the pore structure in the porous compact. This study derives a new quantitative parameter, $S_a$, to describe the anisotropy in pore structure of pharmaceutical tablets based on terahertz time-domain spectrosc...

Rigid pricing and rationally inattentive consumer

Czech Academy of Sciences Publication Activity Database

Matějka, Filip

158 B, July (2015), s. 656-678 ISSN 0022-0531 Institutional support: RVO:67985998 Keywords : rational inattention * imperfect information * nominal rigidity Subject RIV: AH - Economics Impact factor: 1.097, year: 2015

Periodic molybdenum disc array for light trapping in amorphous silicon layer

Energy Technology Data Exchange (ETDEWEB)

Wang, Jiwei; Deng, Changkai [International Center of Quantum and Molecular Structures, Materials Genome Institute, and Department of Physics, Shanghai University, 99 Shangda Road, Shanghai, 200444 China (China); Shanghai Advanced Research Institute, Chinese Academy of Sciences, 99 Haike Road, Shanghai, 201210 China (China); Yang, Kang; Chen, Haiyan, E-mail: chenhy@sari.ac.cn; Li, Dongdong; Chen, Xiaoyuan [Shanghai Advanced Research Institute, Chinese Academy of Sciences, 99 Haike Road, Shanghai, 201210 China (China); Ren, Wei, E-mail: renwei@shu.edu.cn [International Center of Quantum and Molecular Structures, Materials Genome Institute, and Department of Physics, Shanghai University, 99 Shangda Road, Shanghai, 200444 China (China)

2016-05-15

We demonstrate the light trapping effect in amorphous silicon (a-Si:H) layer by inserting a layer of periodic molybdenum disc array (MDA) between the a-Si:H layer and the quartz substrate, which forms a three-layer structure of Si/MDA/SiO{sub 2}. The MDA layer was fabricated by a new cost-effective method based on nano-imprint technology. Further light absorption enhancement was realized through altering the topography of MDA by annealing it at 700°C. The mechanism of light absorption enhancement in a-Si:H interfaced with MDA was analyzed, and the electric field distribution and light absorption curve of the different layers in the Si/MDA structure under light illumination of different wavelengths were simulated by employing numerical finite difference time domain (FDTD) solutions.

Irradiation-induced amorphization process in graphite

Energy Technology Data Exchange (ETDEWEB)

Abe, Hiroaki [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1996-04-01

Effects of the element process of irradiation damage on irradiation-induced amorphization processes of graphite was studied. High orientation thermal decomposed graphite was cut about 100 nm width and used as samples. The irradiation experiments are carried out under the conditions of electronic energy of 100-400 KeV, ion energy of 200-600 KeV, ionic species Xe, Ar, Ne, C and He and the irradiation temperature at from room temperature to 900 K. The critical dose ({phi}a) increases exponentially with increasing irradiation temperature. The displacement threshold energy of graphite on c-axis direction was 27 eV and {phi}a{sup e} = 0.5 dpa. dpa is the average number of displacement to atom. The critical dose of ion irradiation ({phi}a{sup i}) was 0.2 dpa at room temperature, and amorphous graphite was produced by less than half of dose of electronic irradiation. Amorphization of graphite depending upon temperature is discussed. (S.Y.)

Inelastic neutron scattering of amorphous ice

International Nuclear Information System (INIS)

Fukazawa, Hiroshi; Ikeda, Susumu; Suzuki, Yoshiharu

2001-01-01

We measured the inelastic neutron scattering from high-density amorphous (HDA) and low-density amorphous (LDA) ice produced by pressurizing and releasing the pressure. We found a clear difference between the intermolecular vibrations in HDA and those in LDA ice: LDA ice has peaks at 22 and 33 meV, which are also seen in the spectrum of lattice vibrations in ice crystal, but the spectrum of HDA ice does not have these peaks. The excitation energy of librational vibrations in HDA ice is 10 meV lower than that in LDA ice. These results imply that HDA ice includes 2- and 5-coordinated hydrogen bonds that are created by breakage of hydrogen bonds and migration of water molecules into the interstitial site, while LDA ice contains mainly 4-coordinated hydrogen bonds and large cavities. Furthermore, we report the dynamical structure factor in the amorphous ice and show that LDA ice is more closely related to the ice crystal structure than to HDA ice. (author)

Formation of amorphous layers by irradiation

International Nuclear Information System (INIS)

Bourgoin, J.C.

1979-01-01

When an ordered solid is irradiated with heavy energy particles, disorder is produced. When the irradiation dose exceeds a so-called critical dose, the irradiated area of the solid becomes uniformly disordered. Mention is first made of the nature, concentration and distribution of the defects created by a heavy energy particle. The description is then given -solely with respect to semiconductors- of the effect of the various parameters on the critical dose energy and nature of the ion, nature and temperature of the solid, irradiation flux. The physical properties (electronic and thermodynamic types) and the uniformly disordered areas are briefly discussed and these properties are compared with those of amorphous semiconductor layers fabricated by evaporation. It is concluded that the evaporated and irradiated layers are similar in nature. It is suggested that the transformation of an irradiated crystalline area into an amorphous one occurs when the Gibbs energy of the crystal become greater than the Gibbs energy of the amorphous one [fr

Precipitation of amorphous SiO2 particles and their properties

Directory of Open Access Journals (Sweden)

S. Musić

2011-03-01

Full Text Available The experimental conditions were optimized for the synthesis of amorphous SiO2 particles by the reaction of neutralization of sodium silicate solution with H2SO4 solution. Amorphous SiO2 particles were characterized by XRD, FT-IR, FE-SEM, EDS and microelectrophoresis. The amorphous peak was located at 2θ = 21.8º in the XRD pattern. Primary SiO2 particles were ~ 15 to ~ 30 nm in size and they aggregated into bigger particles. Amorphous SiO2 particles showed a specific surface area up to 130 m²g-1, dependent on the parameters of the precipitation process. The EDS spectrum of amorphous SiO2 particles did not show contamination with sulfate or other ions, which cannot be excluded in traces. pHzpc =1.7 was obtained by microelectrophoresis.

Infrared Spectra and Optical Constants of Elusive Amorphous Methane

Science.gov (United States)

Gerakines, Perry A.; Hudson, Reggie L.

2015-01-01

New and accurate laboratory results are reported for amorphous methane (CH4) ice near 10 K for the study of the interstellar medium (ISM) and the outer Solar System. Near- and mid-infrared (IR) data, including spectra, band strengths, absorption coefficients, and optical constants, are presented for the first time for this seldom-studied amorphous solid. The apparent IR band strength near 1300 cm(exp -1) (7.69 micrometer) for amorphous CH4 is found to be about 33% higher than the value long used by IR astronomers to convert spectral observations of interstellar CH4 into CH4 abundances. Although CH4 is most likely to be found in an amorphous phase in the ISM, a comparison of results from various laboratory groups shows that the earlier CH4 band strength at 1300 cm(exp -1) (7.69 micrometer) was derived from IR spectra of ices that were either partially or entirely crystalline CH4 Applications of the new amorphous-CH4 results are discussed, and all optical constants are made available in electronic form.

Amorphous and Nanocomposite Materials for Energy-Efficient Electric Motors

Science.gov (United States)

Silveyra, Josefina M.; Xu, Patricia; Keylin, Vladimir; DeGeorge, Vincent; Leary, Alex; McHenry, Michael E.

2016-01-01

We explore amorphous soft-magnetic alloys as candidates for electric motor applications. The Co-rich system combines the benefits of low hysteretic and eddy-current losses while exhibiting negligible magnetostriction and robust mechanical properties. The amorphous precursors can be devitrified to form nanocomposite magnets. The superior characteristics of these materials offer the advantages of ease of handling in the manufacturing processing and low iron losses during motor operation. Co-rich amorphous ribbons were laser-cut to build a stator for a small demonstrator permanent-magnet machine. The motor was tested up to ~30,000 rpm. Finite-element analyses proved that the iron losses of the Co-rich amorphous stator were ~80% smaller than for a Si steel stator in the same motor, at 18,000 rpm (equivalent to an electric frequency of 2.1 kHz). These low-loss soft magnets have great potential for application in highly efficient high-speed electric machines, leading to size reduction as well as reduction or replacement of rare earths in permanent-magnet motors. More studies evaluating further processing techniques for amorphous and nanocomposite materials are needed.

Amorphous silica from rice husk at various temperatures

International Nuclear Information System (INIS)

Javed, S.J.; Feroze, N.; Tajwar, S.

2008-01-01

Rice husk is being used as a source of energy in many heat generating system because of its high calorific value and its availability in many rice producing areas. Rice husk contains approximately 20% silica which is presented in hydrated form. This hydrated silica can be retrieved as amorphous silica under controlled thermal conditions. Uncontrolled burning of rice husk produces crystalline silica which is not reactive silica but can be used as filler in many applications. Amorphous silica is reactive silica which has better market value due to its reactive nature in process industry. The present study deals with the production of amorphous silica at various temperatures from rice husk. Various ashes were prepared in tube furnace by changing the burning temperatures for fixed time intervals and analyzed by XRD. It has been observed that for two hours calculation's of rice husk renders mostly amorphous silica at 650 degree C where as at higher temperatures crystalline silica was obtained. (author)

Initial Development of an Electronic Testis Rigidity Tester

Directory of Open Access Journals (Sweden)

Petros Mirilas

2011-01-01

Full Text Available We aimed to develop our previously presented mechanical device, the Testis Rigidity Tester (TRT, into an electronic system (Electronic Testis Rigidity Tester, ETRT by applying tactile imaging, which has been used successfully with other solid organs. A measuring device, located at the front end of the ETRT incorporates a tactile sensor comprising an array of microsensors. By application of a predetermined deformation of 2 mm, increased pressure alters linearly the resistance of each microsensor, producing changes of voltage. These signals were amplified, filtered, and digitized, and then processed by an electronic collector system, which presented them as a color-filled contour plot of the area of the testis coming into contact with the sensor. Testis models of different rigidity served for initial evaluation of ETRT; their evacuated central spaces contained different, increasing glue masses. An independent method of rigidity measurement, using an electric weight scale and a micrometer, showed that the more the glue injected, the greater the force needed for a 2-mm deformation. In a preliminary test, a single sensor connected to a multimeter showed similar force measurement for the same deformation in these phantoms. For each of the testis models compressed in the same manner, the ETRT system offered a map of pressures, represented by a color scale within the contour plot of the contact area with the sensor. ETRT found certain differences in rigidity between models that had escaped detection by a blind observer. ETRT is easy to use and provides a color-coded “insight“ of the testis internal structure. After experimental testing, it could be valuable in intraoperative evaluation of testes, so that the surgeon can decide about orchectomy or orcheopexy.

Signature of Thermal Rigidity Percolation

International Nuclear Information System (INIS)

Huerta, Adrián

2013-01-01

To explore the role that temperature and percolation of rigidity play in determining the macroscopic properties, we propose a model that adds translational degrees of freedom to the spins of the well known Ising hamiltonian. In particular, the Ising model illustrate the longstanding idea that the growth of correlations on approach to a critical point could be describable in terms of the percolation of some sort of p hysical cluster . For certain parameters of this model we observe two well defined peaks of C V , that suggest the existence of two kinds of p hysical percolation , namely connectivity and rigidity percolation. Thermal fluctuations give rise to two different kinds of elementary excitations, i.e. droplets and configuron, as suggested by Angell in the framework of a bond lattice model approach. The later is reflected in the fluctuations of redundant constraints that gives stability to the structure and correlate with the order parameter

Rigid pricing and rationally inattentive consumer

Czech Academy of Sciences Publication Activity Database

Matějka, Filip

158 B, July (2015), s. 656-678 ISSN 0022-0531 Institutional support: PRVOUK-P23 Keywords : rational inattention * imperfect information * nominal rigidity Subject RIV: AH - Economics Impact factor: 1.097, year: 2015

Definition and properties of ideal amorphous structures

International Nuclear Information System (INIS)

Stachurski, Z.H.

2002-01-01

Full text: Amorphous structure is usually defined by what it is not (ie, no crystalline peaks in XRS, no bond correlation in NMR), rather than by what it is. The interest in defining the structure of non-crystalline materials is long standing; packing geometry of spheres, molecular structure of glassy SiO 2 , or the structure of atactic polymers are prime examples. The earliest definitions of amorphous structure were in terms of a microcrystallite model of Valenkov, or continuous random network by Zachariasen. The random close packing of spheres of equal size, and an amorphous structure, composed of freely jointed linear chains of hard spheres, has been described mathematically in terms of a linear homogeneous Poisson process. This paper aims to describe some geometrical, kinematic, and topological properties of these two ideal amorphous structures, which belong to the same amorphous class. The geometry of packing is elucidated, and the use of Voronoi tessellation method for measuring the structures is described. The ideal amorphous solid has no symmetry elements; its volume can not be divided into identical unit cells. However, there is a volume element small enough to allow the distinction of its nanoscopic inhomogeneities, and sufficiently large enough to represent, accurately the overall behaviour. We define this volume element, the representative volume element. Suitable boundary conditions must be prescribed for a choice of RVE, and satisfy certain requirements. Topologically, a catchment region on the Born-Oppenheimer potential energy surface over nuclear configuration space, is defined by Mezey and Bader as an energetically stable geometry of the open region of R 3 traversed by all the trajectories which terminate at a local maximum. Two topological properties will be described: (i) the boundaries of the catchment region as a direct geometrical correspondence to the Voronoi polyhedron for a given atom in a given structure, and (ii) the constriction points

Accuracy limit of rigid 3-point water models

Science.gov (United States)

Izadi, Saeed; Onufriev, Alexey V.

2016-08-01

Classical 3-point rigid water models are most widely used due to their computational efficiency. Recently, we introduced a new approach to constructing classical rigid water models [S. Izadi et al., J. Phys. Chem. Lett. 5, 3863 (2014)], which permits a virtually exhaustive search for globally optimal model parameters in the sub-space that is most relevant to the electrostatic properties of the water molecule in liquid phase. Here we apply the approach to develop a 3-point Optimal Point Charge (OPC3) water model. OPC3 is significantly more accurate than the commonly used water models of same class (TIP3P and SPCE) in reproducing a comprehensive set of liquid bulk properties, over a wide range of temperatures. Beyond bulk properties, we show that OPC3 predicts the intrinsic charge hydration asymmetry (CHA) of water — a characteristic dependence of hydration free energy on the sign of the solute charge — in very close agreement with experiment. Two other recent 3-point rigid water models, TIP3PFB and H2ODC, each developed by its own, completely different optimization method, approach the global accuracy optimum represented by OPC3 in both the parameter space and accuracy of bulk properties. Thus, we argue that an accuracy limit of practical 3-point rigid non-polarizable models has effectively been reached; remaining accuracy issues are discussed.

Phonon excitations in multicomponent amorphous solids

International Nuclear Information System (INIS)

Vakarchuk, I.A.; Migal', V.M.; Tkachuk, V.M.

1988-01-01

The method of two-time temperature-dependent Green's functions is used to investigate phonon excitations in multicomponent amorphous solids. The equation obtained for the energy spectrum of the phonon excitations takes into account the damping associated with scattering of phonons by structure fluctuations. The quasicrystal approximation is considered, and as an example explicit expressions are obtained for the case of a two-component amorphous solid for the frequencies of the acoustical and optical modes and for the longitudinal and transverse velocities of sound. The damping is investigated

A Comparison of Photo-Induced Hysteresis Between Hydrogenated Amorphous Silicon and Amorphous IGZO Thin-Film Transistors.

Science.gov (United States)

Ha, Tae-Jun; Cho, Won-Ju; Chung, Hong-Bay; Koo, Sang-Mo

2015-09-01

We investigate photo-induced instability in thin-film transistors (TFTs) consisting of amorphous indium-gallium-zinc-oxide (a-IGZO) as active semiconducting layers by comparing with hydrogenated amorphous silicon (a-Si:H). An a-IGZO TFT exhibits a large hysteresis window in the illuminated measuring condition but no hysteresis window in the dark condition. On the contrary, a large hysteresis window measured in the dark condition in a-Si:H was not observed in the illuminated condition. Even though such materials possess the structure of amorphous phase, optical responses or photo instability in TFTs looks different from each other. Photo-induced hysteresis results from initially trapped charges at the interface between semiconductor and dielectric films or in the gate dielectric which possess absorption energy to interact with deep trap-states and affect the movement of Fermi energy level. In order to support our claim, we also perform CV characteristics in photo-induced hysteresis and demonstrate thermal-activated hysteresis. We believe that this work can provide important information to understand different material systems for optical engineering which includes charge transport and band transition.

Plasma deposition of amorphous silicon-based materials

CERN Document Server

Bruno, Giovanni; Madan, Arun

1995-01-01

Semiconductors made from amorphous silicon have recently become important for their commercial applications in optical and electronic devices including FAX machines, solar cells, and liquid crystal displays. Plasma Deposition of Amorphous Silicon-Based Materials is a timely, comprehensive reference book written by leading authorities in the field. This volume links the fundamental growth kinetics involving complex plasma chemistry with the resulting semiconductor film properties and the subsequent effect on the performance of the electronic devices produced. Key Features * Focuses on the plasma chemistry of amorphous silicon-based materials * Links fundamental growth kinetics with the resulting semiconductor film properties and performance of electronic devices produced * Features an international group of contributors * Provides the first comprehensive coverage of the subject, from deposition technology to materials characterization to applications and implementation in state-of-the-art devices.

Emerging trends in the stabilization of amorphous drugs

DEFF Research Database (Denmark)

Laitinen, Riikka; Löbmann, Korbinian; Strachan, Clare J.

2013-01-01

The number of active pharmaceutical substances having high therapeutic potential but low water solubility is constantly increasing, making it difficult to formulate these compounds as oral dosage forms. The solubility and dissolution rate, and thus potentially the bioavailability, of these poorly...... water-soluble drugs can be increased by the formation of stabilized amorphous forms. Currently, formulation as solid polymer dispersions is the preferred method to enhance drug dissolution and to stabilize the amorphous form of a drug. The purpose of this review is to highlight emerging alternative...... of mesoporous silicon and silica-based carriers are presented as potential means to increase the stability of amorphous pharmaceuticals....

Nitrided FeB amorphous thin films for magneto mechanical systems

International Nuclear Information System (INIS)

Fernandez-Martinez, I.; Martin-Gonzalez, M.S.; Gonzalez-Arrabal, R.; Alvarez-Sanchez, R.; Briones, F.; Costa-Kraemer, J.L.

2008-01-01

The structural, magnetic and magnetoelastic properties of Fe-B-N amorphous films, sputtered from a Fe 80 B 20 target, in a mixture of argon and nitrogen gas, are studied for different nitrogen partial pressures. Nitrogen incorporates into the film preserving the amorphous structure, and modifying magnetic properties. The amount of nitrogen that incorporates into the amorphous structure is found to scale linearly with the nitrogen partial pressure during film growth. The structure, magnetization, field evolution, magnetic anisotropy and magnetostrictive behaviour are determined for films with different nitrogen content. An ∼20% increase of both the saturation magnetization and the magnetostriction constant values is found for moderate (∼8%) nitrogen content when compared to those for pure Fe 80 B 20 amorphous films. These improved properties, together with the still low coercivity of the amorphous films offer great potential for their use in magnetostrictive micro and nano magneto mechanical actuator devices

Mechanics of amorphous solids—identification and constitutive modelling

NARCIS (Netherlands)

van Dommelen, J.A.W.; Estevez, R.

2018-01-01

Both polymers and metals can be in an organised crystalline or amorphous glassy state, where for polymers usually at least a part of the structure is amorphous and metals are in a glassy state only when processed under special conditions. At the 15th European Mechanics of Materials Conference in

Unidirectional effect in domain wall propagation observed in bistable glass-coated microwire

Energy Technology Data Exchange (ETDEWEB)

Onufer, J., E-mail: jozef.onufer@tuke.sk; Ziman, J., E-mail: jan.ziman@tuke.sk; Kladivová, M., E-mail: maria.kladivova@tuke.sk

2015-12-15

Systematic study of domain wall velocity versus applied magnetic field dependences in glass-coated amorphous Fe{sub 77.5}Si{sub 7.5}B{sub 15} wire was carried out, revealing the existence of a very interesting phenomenon. Domain wall mobility can be significantly different in cases when magnetization reversal caused by domain wall motion results in different orientation of magnetization. The magnitude and sign of this so-called unidirectional effect can change along the wire. There are also samples with weak unidirectional effect in which it is possible, in regions of higher values of applied magnetic field, to observe the highest wall velocities. It is very probable that damping of domain wall motion is responsible for this effect. As a hypothesis a mechanism based on eddy current damping of domain wall motion was proposed for interpretation of this effect. In the framework of this mechanism asymmetric and non-linear volt-ampere characteristics of the metal–glass interface might be responsible for the unidirectional effect. - Highlights: • Unidirectional effect in domain wall propagation was observed. • The magnitude and sign of the unidirectional effect can change along the wire. • A hypothesis for interpretation of the unidirectional effect is proposed.

Verification of the Rigidity of the Coulomb Field in Motion

Science.gov (United States)

Blinov, S. V.; Bulyzhenkov, I. É.

2018-06-01

Laplace, analyzing the stability of the Solar System, was the first to calculate that the velocity of the motion of force fields can significantly exceed the velocity of light waves. In electrodynamics, the Coulomb field should rigidly accompany its source for instantaneous force action in distant regions. Such rigid motion was recently inferred from experiments at the Frascati Beam Test Facility with short beams of relativistic electrons. The comments of the authors on their observations are at odds with the comments of theoreticians on retarded potentials, which motivates a detailed study of the positions of both sides. Predictions of measurements, based on the Lienard-Wiechert potentials, are used to propose an unambiguous scheme for testing the rigidity of the Coulomb field. Realization of the proposed experimental scheme could independently refute or support the assertions of the Italian physicists regarding the rigid motion of Coulomb fields and likewise the nondual field approach to macroscopic reality.

Ratchet Effects and Domain Wall Energy Landscapes in Amorphous Magnetic Films with 2D Arrays of Asymmetric Holes

Science.gov (United States)

Martin, J. I.; Alija, A.; Sobrado, I.; Perez-Junquera, A.; Rodriguez-Rodriguez, G.; Velez, M.; Alameda, J. M.; Marconi, V. I.; Kolton, A. B.; Parrondo, J. M. R.

2009-03-01

The driven motion of domain walls in extended magnetic films patterned with 2D arrays of asymmetric holes has been found to be subject to two different crossed ratchet effects [1] which results in an inversion of the sign of domain wall motion rectification as a function of the applied magnetic field. This effect can be understood in terms of the competition between drive, elasticity and asymmetric pinning as revealed by a simple 4̂-model. In order to optimize the asymmetric hole design, the relevant energy landscapes for domain wall motion across the array of asymmetric holes have been calculated by micromagnetic simulations as a function of array geometrical characteristics. The effects of a transverse magnetic field on these two crossed ratchet effects will also be discussed in terms of the decrease in domain wall energy per unit area and of the modifications in the magnetostatic barriers for domain wall pinning at the asymmetric inclusions. Work supported by Spanish MICINN.[1] A. Perez-Junquera et al, Phys. Rev. Lett. 100 (2008) 037203

Financial Constraints and Nominal Price Rigidities

DEFF Research Database (Denmark)

Menno, Dominik Francesco; Balleer, Almut; Hristov, Nikolay

This paper investigates how financial market imperfections and the frequency of price adjustment interact. Based on new firm-level evidence for Germany, we document that financially constrained firms adjust prices more often than their unconstrained counterparts, both upwards and downwards. We show...... that these empirical patterns are consistent with a partial equilibrium menu-cost model with a working capital constraint. We then use the model to show how the presence of financial frictions changes profits and the price distribution of firms compared to a model without financial frictions. Our results suggest...... that tighter financial constraints are associated with higher nominal rigidities, higher prices and lower output. Moreover, in response to aggregate shocks, aggregate price rigidity moves substantially, the response of inflation is dampened, while output reacts more in the presence of financial frictions...

Time of isothermal holding in the course of in-air heat treatment of soft magnetic Fe-based amorphous alloys and their magnetic properties

Science.gov (United States)

Skulkina, N. A.; Ivanov, O. A.; Pavlova, I. O.; Minina, O. A.

2011-12-01

On the example of soft magnetic Fe81B13Si4C2 and Fe77Ni1Si9B13 amorphous alloys, the relation between the level of magnetic properties and duration of isothermal holding in the course of heat treatment in air has been studied. The optimum temperature-dependent time τ of isothermal holding has been shown to be related to the volume fraction of domains ( V orth) with orthogonal magnetization in the initial (quenched) ribbon by equation V orth = ττ1/3. A temperature dependence of the proportionality coefficient α, which determines the degree of diffusion-process activity, has been determined. The results obtained allow us to substantially simplify the choice of optimum conditions of atmospheric heat treatment of soft magnetic Fe-based amorphous ribbons.

Transient photoconductivity in amorphous semiconductors

International Nuclear Information System (INIS)

Mpawenayo, P.

1997-07-01

Localized states in amorphous semiconductors are divided in disorder induced shallow trap levels and dangling bonds deep states. Dangling bonds are assumed here to be either neutral or charged and their energy distribution is a single gaussian. Here, it is shown analytically that transient photocurrent in amorphous semiconductors is fully controlled by charge carriers transitions between localized states for one part and tunneling hopping carriers on the other. Localized dangling bonds deep states act as non radiative recombination centres, while hopping tunnelling is assisted by the Coulomb interaction between defects sites. The half-width of defects distribution is the disorder parameter that determines the carrier hopping time between defects sites. The macroscopic time that explains the long decay response times observed will all types of amorphous semiconductors is duly thought to be temperature dependent. Basic equations developed by Longeaud and Kleider are solved for the general case of a semiconductor after photo-generation. It turns out that the transient photoconductivity decay has two components; one with short response times from carriers trap-release transitions between shallow levels and extended states and a hopping component made of inter-dependent exponentials whose time constants span in larger ranges depending on disorder. The photoconductivity hopping component appears as an additional term to be added to photocurrents derived from existing models. The results of the present study explain and complete the power law decay derived in the multiple trapping models developed 20 years ago only in the approximation of the short response time regime. The long response time regime is described by the hopping macroscopic time. The present model is verified for all samples of amorphous semiconductors known so far. Finally, it is proposed to improved the modulated photoconductivity calculation techniques by including the long-lasting hopping dark documents

Dynamics of sandwich domain structure in Co-based amorphous ribbons with helical magnetic anisotropy: Part I

International Nuclear Information System (INIS)

Zhmetko, D.N.; Zhmetko, S.D.

2009-01-01

The distribution of axes of easy magnetization close to a homogeneous distribution is revealed in each half-thickness of a ribbon after annealing it in a helical magnetic field. The transition from magnetic reversal of a ribbon by the displacement of two domain walls formed near a middle plane of a ribbon to magnetic reversal of a ribbon by displacement of two domain walls formed near to the main surfaces of a ribbon is found out during each half-period of a magnetic reversal.

Centimeter-order view for magnetic domain imaging with local magnetization direction by longitudinal Kerr effect

Directory of Open Access Journals (Sweden)

Sakae Meguro

2016-05-01

Full Text Available An observation system of centimeter-order of view of magnetic domain with local magnetization direction was developed by designing a telecentric optical system of finite design through the extension of microscope technology. The field of view realized in the developed system was 1.40 × 1.05 cm as suppressing defocus and distortion. Detection of the local magnetization direction has become possible by longitudinal Kerr observation from the orthogonal two directions. This system can be applied to the domain observation of rough surface samples and time resolved analysis for soft magnetic materials such as amorphous foil strips and soft magnetic thin films.

Magnetic structure of deformation-induced shear bands in amorphous Fe{sub 80}B{sub 16}Si{sub 4} observed by magnetic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Brown, G.W. [Center for Materials Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Hawley, M.E. [Materials Science and Technology Division, (MST-8), Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Markiewicz, D.J. [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States); Spaepen, F.; Barth, E.P. [Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States)

1999-04-01

Processing-induced magnetic structures in amorphous metallic alloys are of interest because of their impact on the performance of materials used in electric device applications. Plastic deformation associated with cutting or bending the material to the desired shape occurs through the formation of shear bands. The stress associated with these shear bands induces magnetic domains that can lead to power losses through interaction with the fields and currents involved in normal device operation. These domains have been studied previously using a variety of techniques capable of imaging magnetic domain structures. In an effort to better characterize and understand these issues, we have applied atomic and magnetic force microscopy to these materials to provide three-dimensional nanometer-scale topographic resolution and micrometer-scale magnetic resolution. {copyright} {ital 1999 American Institute of Physics.}

Fast and anisotropic flexibility-rigidity index for protein flexibility and fluctuation analysis

Energy Technology Data Exchange (ETDEWEB)

Opron, Kristopher [Department of Biochemistry and Molecular Biology, Michigan State University, Michigan 48824 (United States); Xia, Kelin [Department of Mathematics, Michigan State University, Michigan 48824 (United States); Wei, Guo-Wei, E-mail: wei@math.msu.edu [Department of Biochemistry and Molecular Biology, Michigan State University, Michigan 48824 (United States); Department of Mathematics, Michigan State University, Michigan 48824 (United States); Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824 (United States)

2014-06-21

Protein structural fluctuation, typically measured by Debye-Waller factors, or B-factors, is a manifestation of protein flexibility, which strongly correlates to protein function. The flexibility-rigidity index (FRI) is a newly proposed method for the construction of atomic rigidity functions required in the theory of continuum elasticity with atomic rigidity, which is a new multiscale formalism for describing excessively large biomolecular systems. The FRI method analyzes protein rigidity and flexibility and is capable of predicting protein B-factors without resorting to matrix diagonalization. A fundamental assumption used in the FRI is that protein structures are uniquely determined by various internal and external interactions, while the protein functions, such as stability and flexibility, are solely determined by the structure. As such, one can predict protein flexibility without resorting to the protein interaction Hamiltonian. Consequently, bypassing the matrix diagonalization, the original FRI has a computational complexity of O(N{sup 2}). This work introduces a fast FRI (fFRI) algorithm for the flexibility analysis of large macromolecules. The proposed fFRI further reduces the computational complexity to O(N). Additionally, we propose anisotropic FRI (aFRI) algorithms for the analysis of protein collective dynamics. The aFRI algorithms permit adaptive Hessian matrices, from a completely global 3N × 3N matrix to completely local 3 × 3 matrices. These 3 × 3 matrices, despite being calculated locally, also contain non-local correlation information. Eigenvectors obtained from the proposed aFRI algorithms are able to demonstrate collective motions. Moreover, we investigate the performance of FRI by employing four families of radial basis correlation functions. Both parameter optimized and parameter-free FRI methods are explored. Furthermore, we compare the accuracy and efficiency of FRI with some established approaches to flexibility analysis, namely

Irradiation induced crystalline to amorphous transition

International Nuclear Information System (INIS)

Bourgoin, J.

1980-01-01

Irradiation of a crystalline solid with energetic heavy particles results in cascades of defects which, with increasing dose, overlap and form a continuous disordered layer. In semiconductors the physical properties of such disordered layers are found to be similar to those of amorphous layers produced by evaporation. It is shown in the case of silicon, that the transition from a disordered crystalline (X) layer to an amorphous (α) layer occurs when the Gibbs energy of the X phase and of the defects it contains becomes larger than the Gibbs energy of the α phase. (author)

Perception of preference and risk-taking in laparoscopy, transgastric, and rigid-hybrid transvaginal NOTES for cholecystectomy.

Science.gov (United States)

Sulz, Michael C; Zerz, Andreas; Sagmeister, Markus; Roll, Thomas; Meyenberger, Christa

2013-12-03

Few data are available regarding patients' perceptions of new cholecystectomy (CC) techniques, in the context of the patients' risk behaviours. We investigated patients' preferences for transgastric pure natural orifice translumenal endoscopic surgery (NOTES; transgastric NCC) and rigid-hybrid transvaginal NOTES CC (tvNCC) compared with the standard laparoscopic CC (SL-CC), and patients' risk behaviours. A total of 140 inpatients scheduled for elective laparoscopic CC were enrolled in this prospective single-centre study, from January 2009 to January 2010. Patients judged the potential advantages and disadvantages of transgastric NCC and tvNCC compared with SL-CC. The individual's risk behaviour was analysed by means of the validated 40-item Domain-Specific Risk Attitude Scale (DOSPERT). Of the 140 recruited patients, 57 (65% females; mean age 51.5 years) were analysed. Twenty-five percent of males opted for transgastric NCC and 75% opted for SL-CC. Among females, 10.8%, 37.8% and 51.4% opted for transgastric NCC, tvNCC and SL-CC, respectively. Faster convalescence was graded as the primary potential advantage of transgastric NCC, whereas the potential risk of long-term stomach injuries was considered a primary disadvantage. Females graded the reduction of hospital-acquired morbidity as the primary advantage of tvNCC. The risk assessment showed significantly more risk-taking behaviour in the recreational domain of life among patients who opted for innovative surgical techniques than among those opting for conventional surgery. Transgastric NCC is rarely accepted by females but accepted by a quarter of males. Females consider rigid-hybrid tvNCC and SL-CC similarly attractive. Despite promising new techniques, three-quarters of male and one half of female patients still prefer the standard laparoscopic CC.

Preparation and recrystallization behavior of spray-dried co-amorphous naproxen-indomethacin

DEFF Research Database (Denmark)

Beyer, Andreas; Radi, Lydia; Grohganz, Holger

2016-01-01

(2) factorial design and the obtained samples were analyzed with X-ray powder diffractometry and Fourier-transformed infrared spectroscopy. Evaluation of the data revealed that the preparation of fully amorphous samples could be achieved depending on the process conditions. The resulting recrystallization......To improve the dissolution properties and the physical stability of amorphous active pharmaceutical ingredients, small molecule stabilizing agents may be added to prepare co-amorphous systems. The objective of the study was to investigate if spray-drying allows the preparation of co-amorphous drug...

Moessbauer effect study on mechanically alloyed amorphous Fe1-xTix alloys

International Nuclear Information System (INIS)

Chen Hong; Xu Zuxiong; Ma Ruzhang; Zhao Zhongtao; Ping Jueyun

1994-01-01

Amorphous Fe 1-x Ti x (x = 0.50, 0.60) powders were produced by mechanical alloying from pure elemental powders in a vibratory ball-mill. X-ray diffraction (XRD) and Moessbauer effect (ME) were used to study the progress of amorphization and the property of hydrogen absorption in Fe-Ti alloys. The amorphization process and the properties of the amorphous phase are discussed. (orig.)

Rigid supersymmetry with boundaries

Energy Technology Data Exchange (ETDEWEB)

Belyaev, D.V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Van Nieuwenhuizen, P. [State Univ. of New York, Stony Brook, NY (United States). C.N. Yang Inst. for Theoretical Physics

2008-01-15

We construct rigidly supersymmetric bulk-plus-boundary actions, both in x-space and in superspace. For each standard supersymmetric bulk action a minimal supersymmetric bulk-plus-boundary action follows from an extended F- or D-term formula. Additional separately supersymmetric boundary actions can be systematically constructed using co-dimension one multiplets (boundary superfields). We also discuss the orbit of boundary conditions which follow from the Euler-Lagrange variational principle. (orig.)

Frontal Tasks and Behavior in Rigid or Tremor-Dominant Parkinson Disease.

Science.gov (United States)

Moretti, Rita; Milner, Vera; Caruso, Paola; Gazzin, Silvia; Rumiati, Raffaella

2017-08-01

Parkinson disease (PD) is not an unambiguous entity, and there is a general consensus for the statement that an akinetic-rigid dominant type of presentation has a worse prognosis, in the follow-up. The aim of our study was to examine the differences in frontal tasks and behavior, in 2 PD naive groups: the rigid and the tremor-dominant types of presentation, according to motor scores. Our study has showed some important differences in frontal tasks and in behavior, performing more apathy, aggressiveness, and irritability in the rigid type, and more depression and anxiety in the tremor-dominant type. The former group causes the caregiver more distress and has a very rapid disease progression. It can be argued that rigid type PD presentation needs specific dedicated cares and more strong clinical attention.

Pharmacological targeting of membrane rigidity: implications on cancer cell migration and invasion

International Nuclear Information System (INIS)

Braig, Simone; Stoiber, Katharina; Zahler, Stefan; Vollmar, Angelika M

2015-01-01

The invasive potential of cancer cells strongly depends on cellular stiffness, a physical quantity that is not only regulated by the mechanical impact of the cytoskeleton but also influenced by the membrane rigidity. To analyze the specific role of membrane rigidity in cancer progression, we treated cancer cells with the Acetyl-CoA carboxylase inhibitor Soraphen A and revealed an alteration of the phospholipidome via mass spectrometry. Migration, invasion, and cell death assays were employed to relate this alteration to functional consequences, and a decrease of migration and invasion without significant impact on cell death has been recorded. Fourier fluctuation analysis of giant plasma membrane vesicles showed that Soraphen A increases membrane rigidity of carcinoma cell membranes. Mechanical measurements of the creep deformation response of whole intact cells were performed using the optical stretcher. The increase in membrane rigidity was observed in one cell line without changing the creep deformation response indicating no restructuring of the cytoskeleton. These data indicate that the increase of membrane rigidity alone is sufficient to inhibit invasiveness of cancer cells, thus disclosing the eminent role of membrane rigidity in migratory processes. (paper)

Crystallization of biogenic hydrous amorphous silica

Science.gov (United States)

Kyono, A.; Yokooji, M.; Chiba, T.; Tamura, T.; Tuji, A.

2017-12-01

Diatom, Nitzschia cf. frustulum, collected from Lake Yogo, Siga prefecture, Japan was cultured in laboratory. Organic components of the diatom cell were removed by washing with acetone and sodium hypochlorite. The remaining frustules were studied by SEM-EDX, FTIR spectroscopy, and synchrotron X-ray diffraction. The results showed that the spindle-shaped morphology of diatom frustule was composed of hydrous amorphous silica. Pressure induced phase transformation of the diatom frustule was investigated by in situ Raman spectroscopic analysis. With exposure to 0.3 GPa at 100 oC, Raman band corresponding to quartz occurred at ν = 465 cm-1. In addition, Raman bands known as a characteristic Raman pattern of moganite was also observed at 501 cm-1. From the integral ratio of Raman bands, the moganite content in the probed area was estimated to be approximately 50 wt%. With the pressure and temperature effect, the initial morphology of diatom frustule was completely lost and totally changed to a characteristic spherical particle with a diameter of about 2 mm. With keeping the compression of 5.7 GPa at 100 oC, a Raman band assignable to coesite appeared at 538 cm-1. That is, with the compression and heating, the hydrous amorphous silica can be readily crystallized into quartz, moganite, and coesite. The first-principles calculations revealed that a disiloxane molecule stabilized in a trans configuration is twisted 60o and changed into the cis configuration with a close approach of water molecule. It is therefore a reasonable assumption that during crystallization of hydrous amorphous silica, the Si-O-Si bridging unit with the cis configuration would survive as a structural defect and then crystallized into moganite by keeping the geometry. This hypothesis is adaptable to the phase transformation from hydrous amorphous silica to coesite as well, because coesite has the four-membered rings and easily formed from the hydrous amorphous silica under high pressure and high

Amorphous Dielectric Thin Films with Extremely Low Mechanical Loss

Directory of Open Access Journals (Sweden)

Liu X.

2015-04-01

Full Text Available The ubiquitous low-energy excitations are one of the universal phenomena of amorphous solids. These excitations dominate the acoustic, dielectric, and thermal properties of structurally disordered solids. One exception has been a type of hydrogenated amorphous silicon (a-Si:H with 1 at.% H. Using low temperature elastic and thermal measurements of electron-beam evap-orated amorphous silicon (a-Si, we show that TLS can be eliminated in this system as the films become denser and more structurally ordered under certain deposition conditions. Our results demonstrate that TLS are not intrinsic to the glassy state but instead reside in low density regions of the amorphous network. This work obviates the role hydrogen was previously thought to play in removing TLS in a-Si:H and favors an ideal four-fold covalently bonded amorphous structure as the cause for the disappearance of TLS. Our result supports the notion that a-Si can be made a “perfect glass” with “crystal-like” properties, thus offering an encouraging opportunity to use it as a simple crystal dielectric alternative in applications, such as in modern quantum devices where TLS are the source of dissipation, decoherence and 1/f noise.

Non-rigid image registration using bone growth model

DEFF Research Database (Denmark)

Bro-Nielsen, Morten; Gramkow, Claus; Kreiborg, Sven

1997-01-01

Non-rigid registration has traditionally used physical models like elasticity and fluids. These models are very seldom valid models of the difference between the registered images. This paper presents a non-rigid registration algorithm, which uses a model of bone growth as a model of the change...... between time sequence images of the human mandible. By being able to register the images, this paper at the same time contributes to the validation of the growth model, which is based on the currently available medical theories and knowledge...

Laser spot welding of cobalt-based amorphous metal foils

International Nuclear Information System (INIS)

Runchev, Dobre; Dorn, Lutc; Jaferi, Seifolah; Purbst, Detler

1997-01-01

The results concerning weldability of amorphous alloy (VAC 6025F) in shape of foils and the quality of laser-spot welded joints are presented in this paper. The aim of the research was the production of a high quality welding joint, by preserving the amorphous structure. The quality of the joint was tested by shear strength analysis and microhardness measuring. The metallographic studies were made by using optical microscope and SEM. The results show that (1) overlapped Co based amorphous metals foils can be welded with high-quality by a pulsed Nd: YAG-Laser, but only within a very narrow laser parameter window; (2) the laser welded spots show comparably high strength as the basic material; (3) the structure of the welded spot remains amorphous, so that the same characteristics as the base material can be achieved. (author)

Amorphous carbon nanofibres inducing high specific capacitance of deposited hydrous ruthenium oxide

International Nuclear Information System (INIS)

Barranco, V.; Pico, F.; Ibanez, J.; Lillo-Rodenas, M.A.; Linares-Solano, A.; Kimura, M.; Oya, A.; Rojas, R.M.; Amarilla, J.M.; Rojo, J.M.

2009-01-01

Composites consisting of ruthenium oxide particles deposited on amorphous carbon nanofibres are prepared by a repetitive impregnation procedure. The choice of amorphous carbon nanofibres as support of amorphous ruthenium oxide leads to composites in which the deposited oxide consists of aggregates of extremely small primary particles (1-1.5 nm-size) and showing high porosity (specific surface area of 450 m 2 g -1 ). This special deposition of the oxide seems to favour: (i) high oxide capacitance (1000 Fg -1 ) at high oxide loadings (up to 20 wt%) and (ii) high capacitance retention (ca. 80% from the initial oxide capacitance) at high current densities (200 mA cm -2 ). Amorphous carbon nanofibres are suitable supports for amorphous ruthenium oxide and perhaps for other amorphous oxides acting as active electrode materials.

Characterization of amorphous and nanocrystalline carbon films

International Nuclear Information System (INIS)

Chu, Paul K.; Li Liuhe

2006-01-01

Amorphous and nanocrystalline carbon films possess special chemical and physical properties such as high chemical inertness, diamond-like properties, and favorable tribological proprieties. The materials usually consist of graphite and diamond microstructures and thus possess properties that lie between the two. Amorphous and nanocrystalline carbon films can exist in different kinds of matrices and are usually doped with a large amount of hydrogen. Thus, carbon films can be classified as polymer-like, diamond-like, or graphite-like based on the main binding framework. In order to characterize the structure, either direct bonding characterization methods or the indirect bonding characterization methods are employed. Examples of techniques utilized to identify the chemical bonds and microstructure of amorphous and nanocrystalline carbon films include optical characterization methods such as Raman spectroscopy, Ultra-violet (UV) Raman spectroscopy, and infrared spectroscopy, electron spectroscopic and microscopic methods such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy, transmission electron microscopy, and electron energy loss spectroscopy, surface morphology characterization techniques such as scanning probe microscopy (SPM) as well as other characterization methods such as X-ray reflectivity and nuclear magnetic resonance. In this review, the structures of various types of amorphous carbon films and common characterization techniques are described

Characterization of Amorphous and Co-Amorphous Simvastatin Formulations Prepared by Spray Drying

DEFF Research Database (Denmark)

Craye, Goedele; Löbmann, Korbinian; Grohganz, Holger

2015-01-01

In this study, spray drying from aqueous solutions, using the surface-active agent sodium lauryl sulfate (SLS) as a solubilizer, was explored as a production method for co-amorphous simvastatin-lysine (SVS-LYS) at 1:1 molar mixtures, which previously have been observed to form a co...

Amorphous Cu-Ag films with high stability

International Nuclear Information System (INIS)

Reda, I.M.; Hafner, J.; Pongratz, P.; Wagendristel, A.; Bangert, H.; Bhat, P.K.

1982-06-01

Films produced by quenching Cu-Ag vapour onto cooled substrates at liquid nitrogen temperature have been investigated using electron microscopy, electron diffraction and electrical resistivity measurements. In the composition range from 30 to 70 at% Cu the as quenched films are amorphous, and within the range of 35 to 63 at% Cu the amorphous phase is stable above room temperature with a maximum crystallization temperature Tsub(c)=381 K at 47.5 at% Cu. Crystallization results in the formation of a supersaturated fcc solid solution which decomposes in a second crystallization step. The effect of deposition rate, film thickness, temperature and surface of the substrate, and most importantly of the composition on the transition temperatures has been investigated. A comparative study of the formation of amorphous phases in a wide variety of Cu-based alloys is presented. (author)

Technique for determination of elastic limit of micron band-thick amorphous

International Nuclear Information System (INIS)

Zakharov, E.K.; Pol'dyaeva, G.P.; Tret'yakov, B.N.

1984-01-01

A method is suggested to determine the elastic limit of micron-thick amorphous band under bending. The elastic limit is determined by bending an amorphous band sample around a series of cylindrical mandrels of gradually decreasing radius. Experimental data on measuring the elastic limit of some amorphous iron base alloys according to the suggested technique are presented. The elastic limit of amorphous alloys is shown to lie in the 3140-4110 MPa range depending on chemical composition, which is about 2-2.5 times higher as compared to high-strength crystal alloys

Safety procedures used during the manufacturing of amorphous silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Dickson, C R

1987-01-01

The Solarex Thin Film Division is a leader in the manufacturing of amorphous-silicon products for sale in domestic and foreign markets. Similarly, Solarex assumes a leadership role in recognizing the importance of safety in a manufacturing environment. Although many of the safety issues are similar to those in the semiconductor industry, this paper presents topics specific to amorphous silicon technology and the manufacturing ,f amorphous-silicon products. These topics are deposition of conducting transparent oxides (CTOs), amorphous silicon deposition, laser scribing, processing chemicals, fire prevention and administrative responsibilities.

Short-range order in amorphous thin films of indium selenides

International Nuclear Information System (INIS)

Zakharov, V.P.; Poltavtsev, Yu.G.; Sheremet, G.P.

1982-01-01

A structure of the short-range order and a character of interatomic interactions in indium selenides Insub(1-x)Sesub(x) with 0.333 <= x <= 0.75, obtained in the form of amorphous films 0.05-0.80 μm thick are studied using electron diffraction method. It is found out that mostly tetrahedrical coordination of nearest neighbours in the vicinity of indium atoms is characteristic for studied amorphous films, and coordination of selenium atoms is different. Amorphous film with x=0.75 posesses a considereably microheterogeneous structure of the short-range order, which is characterized by the presence of microunclusions of amorphous selenium and atoms of indium, octohedrically coordinated by selenium atoms

Immobilization technology for krypton in amorphous zeolite

International Nuclear Information System (INIS)

Takusagawa, Atsushi; Ishiyama, Keiichi

1989-01-01

Radioactive krypton recovered from the offgas of a reprocessing plant requires long-term storage on the order of 100 years. Immobilization technology for krypton into amorphous zeolite 5A is considered one of the best methods for long-term storage. In this report, conditions for immobilization treatment and stability of amorphous zeolite 5A loaded krypton against heat, radiation and water are discussed, and a treatment system using this technology is described. (author)

Structural models for amorphous transition metal binary alloys

International Nuclear Information System (INIS)

Ching, W.Y.; Lin, C.C.

1976-01-01

A dense random packing of 445 hard spheres with two different diameters in a concentration ratio of 3 : 1 was hand-built to simulate the structure of amorphous transition metal-metalloid alloys. By introducing appropriate pair potentials of the Lennard-Jones type, the structure is dynamically relaxed by minimizing the total energy. The radial distribution functions (RDF) for amorphous Fe 0 . 75 P 0 . 25 , Ni 0 . 75 P 0 . 25 , Co 0 . 75 P 0 . 25 are obtained and compared with the experimental data. The calculated RDF's are resolved into their partial components. The results indicate that such dynamically constructed models are capable of accounting for some subtle features in the RDF of amorphous transition metal-metalloid alloys

Cognitive flexibility in verbal and nonverbal domains and decision making in anorexia nervosa patients: a pilot study

Directory of Open Access Journals (Sweden)

Marzola Enrica

2011-10-01

Full Text Available Abstract Background This paper aimed to investigate cognitive rigidity and decision making impairments in patients diagnosed with Anorexia Nervosa Restrictive type (AN-R, assessing also verbal components. Methods Thirty patients with AN-R were compared with thirty age-matched healthy controls (HC. All participants completed a comprehensive neuropsychological battery comprised of the Trail Making Test, Wisconsin Card Sorting Test, Hayling Sentence Completion Task, and the Iowa Gambling Task. The Beck Depression Inventory was administered to evaluate depressive symptomatology. The influence of both illness duration and neuropsychological variables was considered. Body Mass Index (BMI, years of education, and depression severity were considered as covariates in statistical analyses. Results The AN-R group showed poorer performance on all neuropsychological tests. There was a positive correlation between illness duration and the Hayling Sentence Completion Task Net score, and number of completion answers in part B. There was a partial effect of years of education and BMI on neuropsychological test performance. Response inhibition processes and verbal fluency impairment were not associated with BMI and years of education, but were associated with depression severity. Conclusions These data provide evidence that patients with AN-R have cognitive rigidity in both verbal and non-verbal domains. The role of the impairment on verbal domains should be considered in treatment. Further research is warranted to better understand the relationship between illness state and cognitive rigidity and impaired decision-making.

A theoretical and spectroscopic study of co-amorphous naproxen and indomethacin

DEFF Research Database (Denmark)

Löbmann, Korbinian; Laitinen, Riikka; Grohganz, Holger

2013-01-01

. In this study, the co-amorphous drug mixture containing naproxen (NAP) and indomethacin (IND) was investigated using infrared spectroscopy (IR) and quantum mechanical calculations. The structures of both drugs were optimized as monomer, homodimer and heterodimer using density functional theory and used...... for the calculation of IR spectra. Conformational analysis confirmed that the optimized structures were suitable for the theoretical prediction of the spectra. Vibrational modes from the calculation could be matched with experimentally observed spectra for crystalline and amorphous NAP and IND, and it could be shown...... that both drugs exist as homodimers in their respective individual amorphous form. With the results from the experimental single amorphous drugs and theoretical homodimers, a detailed analysis of the experimental co-amorphous and theoretical heterodimer spectra was performed and evaluated. It is suggested...

Towards Sub-Microarsecond Rigid Earth Nutation Series in the Hamiltonian Theory

National Research Council Canada - National Science Library

Souchay, Jean; Folgueira, M

2000-01-01

...) are based on the works of Kinoshita (1977) and Wahr (1979). In Kinoshita's work, the rigid Earth nutation series were calculated by the application of the Hamiltonian canonical equations to the rotation of the rigid and elliptical Earth...

Influence of irradiation spectrum and implanted ions on the amorphization of ceramics

International Nuclear Information System (INIS)

Zinkle, S.J.; Snead, L.L.

1995-01-01

Polycrystalline Al2O3, magnesium aluminate spinel (MgAl2O4), MgO, Si3N4, and SiC were irradiated with various ions at 200-450 K, and microstructures were examined following irradiation using cross-section TEM. Amorphization was not observed in any of the irradiated oxide ceramics, despsite damage energy densities up to ∼7 keV/atom (70 displacements per atom). On the other hand, SiC readily amorphized after damage levels of ∼0.4 dpa at room temperature (RT). Si3N4 exhibited intermediate behavior; irradiation with Fe 2+ ions at RT produced amorphization in the implanted ion region after damage levels of ∼1 dpa. However, irradiated regions outside the implanted ion region did not amorphize even after damage levels > 5 dpa. The amorphous layer in the Fe-implanted region of Si3N4 did not appear if the specimen was simultaneoulsy irradiated with 1-MeV He + ions at RT. By comparison with published results, it is concluded that the implantation of certain chemical species has a pronounced effect on the amorphization threshold dose of all five materials. Intense ionizing radiation inhibits amorphization in Si3N4, but does not appear to significantly influence the amorphization of SiC

A Molecular-Level View of the Physical Stability of Amorphous Solid Dispersions

Science.gov (United States)

Yuan, Xiaoda

Many pharmaceutical compounds being developed in recent years are poorly soluble in water. This has led to insufficient oral bioavailability of many compounds in vitro. The amorphous formulation is one of the promising techniques to increase the oral bioavailability of these poorly water-soluble compounds. However, an amorphous drug substance is inherently unstable because it is a high energy form. In order to increase the physical stability, the amorphous drug is often formulated with a suitable polymer to form an amorphous solid dispersion. Previous research has suggested that the formation of an intimately mixed drug-polymer mixture contributes to the stabilization of the amorphous drug compound. The goal of this research is to better understand the role of miscibility, molecular interactions and mobility on the physical stability of amorphous solid dispersions. Methods were developed to detect different degrees of miscibility on nanometer scale and to quantify the extent of hydrogen-bonding interactions between the drug and the polymer. Miscibility, hydrogen-bonding interactions and molecular mobility were correlated with physical stability during a six-month period using three model systems. Overall, this research provides molecular-level insights into many factors that govern the physical stability of amorphous solid dispersions which can lead to a more effective design of stable amorphous formulations.

A DNA Origami Mechanical Device for the Regulation of Microcosmic Structural Rigidity.

Science.gov (United States)

Wan, Neng; Hong, Zhouping; Wang, Huading; Fu, Xin; Zhang, Ziyue; Li, Chao; Xia, Han; Fang, Yan; Li, Maoteng; Zhan, Yi; Yang, Xiangliang

2017-11-01

DNA origami makes it feasible to fabricate a tremendous number of DNA nanostructures with various geometries, dimensions, and functionalities. Moreover, an increasing amount of research on DNA nanostructures is focused on biological and biomedical applications. Here, the reversible regulation of microcosmic structural rigidity is accomplished using a DNA origami device in vitro. The designed DNA origami monomer is composed of an internal central axis and an external sliding tube. Due to the external tube sliding, the device transforms between flexible and rigid states. By transporting the device into the liposome, the conformational change of the origami device induces a structural change in the liposome. The results obtained demonstrate that the programmed DNA origami device can be applied to regulate the microcosmic structural rigidity of liposomes. Because microcosmic structural rigidity is important to cell proliferation and function, the results obtained potentially provide a foundation for the regulation of cell microcosmic structural rigidity using DNA nanostructures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and densification of Cu-coated Ni-based amorphous composite powders

International Nuclear Information System (INIS)

Kim, Yong-Jin; Kim, Byoung-Kee; Kim, Jin-Chun

2007-01-01

Spherical Ni 57 Zr 20 Ti 16 Si 2 Sn 3 (numbers indicate at.%) amorphous powders were produced by the gas atomization process, and ductile Cu phase was coated on the Ni-based amorphous powders by the spray drying process in order to increase the ductility of the consolidated amorphous alloy. The characteristics of the as-prepared powders and the consolidation behaviors of Cu-coated Ni-based amorphous composite powders were investigated. The atomization was conducted at 1450 deg. C under the vacuum of 10 -2 mbar. The Ni-based amorphous powders and Cu nitrate solution were mixed and sprayed at temperature of 130 deg. C. After spray drying and reduction treatment, the sub-micron size Cu powders were coated successfully on the surface of the atomized Ni amorphous powders. The spark plasma sintering process was applied to study the densification behavior of the Cu-coated composite powders. Thickness of the Cu layer was less than 1 μm. The compacts obtained by SPS showed high relative density of over 98% and its hardness was over 800 Hv

Phase transations in glassy materials

International Nuclear Information System (INIS)

Thorpe, M.F.

1984-01-01

We examine the mechanical properties of covalent random networks with high and low mean coordination. It is shown that networks with high mean coordination (amorphous solids) have elastic constants determined by the covalent forces whereas networks with low mean coordination (polymeric glasses) have elastic constants determined by the longer range molecular forces. These ideas can be made rigorous by considering the number of continuous deformations (i.e. zero frequency modes) allowed within the network. In the transition from one kind of network to another, rigidity percolates through the system. This leads to a picture in wich polymeric glasses have large floppy or spongy regions with a few rigid inclusions. On the other hand in amorphous solids, the rigid regions have percolated to form a rigid solid with a few floppy or spongy inclusions. (Author) [pt

Creep of FINEMET alloy at amorphous to nanocrystalline transition

NARCIS (Netherlands)

Csach, K.; Miškuf, J.; Juríková, A.; Ocelík, V.

2009-01-01

The application of FINEMET-type materials with specific magnetic properties prepared by the crystallization of amorphous alloys is often limited by their brittleness. The structure of these materials consists of nanosized Fe-based grains surrounded with amorphous phase. Then the final macroscopic

Botulinum toxin in myotonia congenita: it does not help against rigidity and pain.

Science.gov (United States)

Dressler, Dirk; Adib Saberi, Fereshte

2014-05-01

Botulinum toxin (BT) is a potent local muscle relaxant with analgetic properties. Myotonia congenita (MC) is a genetic disorder producing muscle rigidity and pain. BT injected into the trapezius produced mild paresis, but no effect on rigidity and pain. There were no signs of systemic effects. Lack of BT efficacy on MC rigidity confirms its origin from muscle membrane dysfunction rather than from inappropriate neuromuscular activation. Lack of BT efficacy on pain could be caused by lack of anti-rigidity effect. It could also be due to separate non-muscular pain mechanisms unresponsive to BT.

Amorphous computing in the presence of stochastic disturbances.

Science.gov (United States)

Chu, Dominique; Barnes, David J; Perkins, Samuel

2014-11-01

Amorphous computing is a non-standard computing paradigm that relies on massively parallel execution of computer code by a large number of small, spatially distributed, weakly interacting processing units. Over the last decade or so, amorphous computing has attracted a great deal of interest both as an alternative model of computing and as an inspiration to understand developmental biology. A number of algorithms have been developed that can take advantage of the massive parallelism of this computing paradigm to solve specific problems. One of the interesting properties of amorphous computers is that they are robust with respect to the loss of individual processing units, in the sense that a removal of some of them should not impact on the computation as a whole. However, much less understood is to what extent amorphous computers are robust with respect to minor disturbances to the individual processing units, such as random motion or occasional faulty computation short of total component failure. In this article we address this question. As an example problem we choose an algorithm to calculate a straight line between two points. Using this example, we find that amorphous computers are not in general robust with respect to Brownian motion and noise, but we find strategies that restore reliable computation even in their presence. We will argue that these strategies are generally applicable and not specific to the particular AC we consider, or even specific to electronic computers. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Structure and low temperature thermal relaxation of amorphized germanium

International Nuclear Information System (INIS)

Glover, C.J.; Ridgway, M.C.; Byrne, A.P.; Clerc, C.; Hansen, J.L.; Larsen, A.N.

1999-01-01

The structure of implantation-induced damage in amorphized Ge has been investigated using high resolution extended x-ray absorption fine structure spectroscopy (EXAFS). EXAFS data analysis was performed with the Cumulant Method, allowing a full reconstruction of the interatomic distance distribution (RDF). For the case of MeV implantation at -196 deg C, for an ion-dose range extending two orders of magnitude beyond that required for amorphization, a dose-dependent asymmetric RDF was determined for the amorphous phase including an increase in bond-length as a function of ion dose. Low-temperature thermal annealing resulted in structural relaxation of the amorphous phase as evidenced by a reduction in the centroid, asymmetry and width of the RDF. Such an effect was attributed to the formation (and subsequent annihilation) of three- and five-fold Co-ordinated atoms, comparing favourably to theoretical simulations of the structure of a-Ge

Calculating ensemble averaged descriptions of protein rigidity without sampling.

Science.gov (United States)

González, Luis C; Wang, Hui; Livesay, Dennis R; Jacobs, Donald J

2012-01-01

Previous works have demonstrated that protein rigidity is related to thermodynamic stability, especially under conditions that favor formation of native structure. Mechanical network rigidity properties of a single conformation are efficiently calculated using the integer body-bar Pebble Game (PG) algorithm. However, thermodynamic properties require averaging over many samples from the ensemble of accessible conformations to accurately account for fluctuations in network topology. We have developed a mean field Virtual Pebble Game (VPG) that represents the ensemble of networks by a single effective network. That is, all possible number of distance constraints (or bars) that can form between a pair of rigid bodies is replaced by the average number. The resulting effective network is viewed as having weighted edges, where the weight of an edge quantifies its capacity to absorb degrees of freedom. The VPG is interpreted as a flow problem on this effective network, which eliminates the need to sample. Across a nonredundant dataset of 272 protein structures, we apply the VPG to proteins for the first time. Our results show numerically and visually that the rigidity characterizations of the VPG accurately reflect the ensemble averaged [Formula: see text] properties. This result positions the VPG as an efficient alternative to understand the mechanical role that chemical interactions play in maintaining protein stability.

Diffuse interface immersed boundary method for multi-fluid flows with arbitrarily moving rigid bodies

Science.gov (United States)

Patel, Jitendra Kumar; Natarajan, Ganesh

2018-05-01

We present an interpolation-free diffuse interface immersed boundary method for multiphase flows with moving bodies. A single fluid formalism using the volume-of-fluid approach is adopted to handle multiple immiscible fluids which are distinguished using the volume fractions, while the rigid bodies are tracked using an analogous volume-of-solid approach that solves for the solid fractions. The solution to the fluid flow equations are carried out using a finite volume-immersed boundary method, with the latter based on a diffuse interface philosophy. In the present work, we assume that the solids are filled with a "virtual" fluid with density and viscosity equal to the largest among all fluids in the domain. The solids are assumed to be rigid and their motion is solved using Newton's second law of motion. The immersed boundary methodology constructs a modified momentum equation that reduces to the Navier-Stokes equations in the fully fluid region and recovers the no-slip boundary condition inside the solids. An implicit incremental fractional-step methodology in conjunction with a novel hybrid staggered/non-staggered approach is employed, wherein a single equation for normal momentum at the cell faces is solved everywhere in the domain, independent of the number of spatial dimensions. The scalars are all solved for at the cell centres, with the transport equations for solid and fluid volume fractions solved using a high-resolution scheme. The pressure is determined everywhere in the domain (including inside the solids) using a variable coefficient Poisson equation. The solution to momentum, pressure, solid and fluid volume fraction equations everywhere in the domain circumvents the issue of pressure and velocity interpolation, which is a source of spurious oscillations in sharp interface immersed boundary methods. A well-balanced algorithm with consistent mass/momentum transport ensures robust simulations of high density ratio flows with strong body forces. The

Size modulation of nanocrystalline silicon embedded in amorphous silicon oxide by Cat-CVD

International Nuclear Information System (INIS)

Matsumoto, Y.; Godavarthi, S.; Ortega, M.; Sanchez, V.; Velumani, S.; Mallick, P.S.

2011-01-01

Different issues related to controlling size of nanocrystalline silicon (nc-Si) embedded in hydrogenated amorphous silicon oxide (a-SiO x :H) deposited by catalytic chemical vapor deposition (Cat-CVD) have been reported. Films were deposited using tantalum (Ta) and tungsten (W) filaments and it is observed that films deposited using tantalum filament resulted in good control on the properties. The parameters which can affect the size of nc-Si domains have been studied which include hydrogen flow rate, catalyst and substrate temperatures. The deposited samples are characterized by X-ray diffraction, HRTEM and micro-Raman spectroscopy, for determining the size of the deposited nc-Si. The crystallite formation starts for Ta-catalyst around the temperature of 1700 o C.

Short range order in amorphous polycondensates

Energy Technology Data Exchange (ETDEWEB)

Lamers, C.; Richter, D.; Schweika, W. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung; Batoulis, J.; Sommer, K. [Bayer AG, Leverkusen (Germany); Cable, J.W. [Oak Ridge National Lab., TN (United States); Shapiro, S.M. [Brookhaven National Lab., Upton, NY (United States)

1992-12-01

The static coherent structure factors S(Q) of the polymer glass Bisphenol-A-Polycarbonate and its chemical variation Bisphenol-A- Polyctherkctone- both in differently deuterated versions- have been measured by spin polarized neutron scattering. The method of spin polarization analysis provided an experimental separation of coherent and incoherent scattering and a reliable intensity calibration. Results are compared to structure factors calculated for model structures which were obtained by ``amorphous cell`` computer simulations. In general reasonable agreement is found between experiment and simulation; however, certain discrepancies hint at an insufficient structural relaxation in the amorphous cell method. 15 refs, 1 fig, 1 tab.

PDF analysis on re-crystallized structure from amorphous BiT

Energy Technology Data Exchange (ETDEWEB)

Yoneda, Yasuhiro [Japan Atomic Energy Research Institute, Synchrotron Radiation Research Center, Kouto 1-1-1, Mikazuki-cho, Sayo-gun, Hyogo 679-5148 (Japan)]. E-mail: yoneda@spring8.or.jp; Kohara, Shinji [Synchrotron Radiation Research Laboratory, Japan Synchrotron Radiation, Research Institute, Kouto 1-1-1, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hamazaki, Shin' ichi [Department of Electronics, Iwaki Meisei University, Iino 5-5-1, Chuohdai, Fukushima 970-8551 (Japan); Takashige, Masaaki [Department of Electronics, Iwaki Meisei University, Iino 5-5-1, Chuohdai, Fukushima 970-8551 (Japan); Mizuki, Jun' ichiro [Japan Atomic Energy Research Institute, Synchrotron Radiation Research Center, Kouto 1-1-1, Mikazuki-cho, Sayo-gun, Hyogo 679-5148 (Japan)

2005-08-15

A glass sample of composition Bi{sub 4}Ti{sub 3}O{sub 12} was prepared by rapid quenching. The as-quenched sample was confirmed to be amorphous by synchrotron X-ray measurements. The crystallization process of the amorphous sample was also investigated by high-energy X-ray diffraction and by atomic pair distribution function analysis. The perovskite layer in the crystal Bi{sub 4}Ti{sub 3}O{sub 12} is transformed to a pyrochlore structure in the amorphous sample. The amorphous sample first crystallized to a metastable phase by acquiring long-range ordering of the pyrochlore structure at T {sub cryst1}, and then secondary crystallized into a reverted Bi{sub 4}Ti{sub 3}O{sub 12} structure at T {sub cryst2}.

Amorphous metal based nanoelectromechanical switch

KAUST Repository

Mayet, Abdulilah M.; Smith, Casey; Hussain, Muhammad Mustafa

2013-01-01

Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

Amorphous metal based nanoelectromechanical switch

KAUST Repository

Mayet, Abdulilah M.

2013-04-01

Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

Nonaffinity in amorphous solids close to the jamming transition

Directory of Open Access Journals (Sweden)

Arévalo Roberto

2017-01-01

Full Text Available Nonaffinity is known to be an integral part of the response of amorphous solids. Its role is particularly relevant in particulate systems close to their jamming transition, where it dominates the elastic response. Thus, to determine the elastic properties of amorphous solids it is essential to rationalize the features of their nonaffine response. Via numerical simulations we investigate the relation between the non affine response and the vibrational properties of model amorphous materials. We show that, contrary to previous speculations, modes below the Boson peak are those mostly responsible for the nonaffine response.

Measurement of the saturation magnetostriction constant of amorphous wire

International Nuclear Information System (INIS)

Mitra, A.; Vazquez, M.

1990-01-01

Measurement of the magnetostriction constant of amorphous wire by conventional techniques is very difficult because of its small diameter. However, accurate determination of the magnetostriction constant is important in the study of amorphous wires. Here the saturation magnetostriction constant (λ s ) for a low-magnetostriction amorphous wire of nominal composition (Fe 6.3 Co 92.7 Nb 1 ) 77.5 Si 7.5 B 15 has been determined by means of the small-angle magnetization-rotation method. λ s has been evaluated to be 2.1x10 -7 for its as-received state. The dependence of thermal treatment is also reported

Surface-Activated Amorphous Alloy Fuel Electrodes for Methanol Fuel Cell

OpenAIRE

Asahi, Kawashima; Koji, Hashimoto; The Research Institute for Iron, Steel and Other Metals; The Research Institute for Iron, Steel and Other Metals

1983-01-01

Amorphous alloy electrodes for electrochemical oxidation of methanol and its derivatives were obtained by the surface activation treatment consisting of electrodeposition of zinc on as-quenched amorphous alloy substrates, heating at 200-300℃ for 30 min, and subsequently leaching of zinc in an alkaline solution. The surface activation treatment provided a new method for the preparation of a large surface area on the amorphous alloys. The best result for oxidation of methanol, sodium formate an...

Superlattice doped layers for amorphous silicon photovoltaic cells

Science.gov (United States)

Arya, Rajeewa R.

1988-01-12

Superlattice doped layers for amorphous silicon photovoltaic cells comprise a plurality of first and second lattices of amorphous silicon alternatingly formed on one another. Each of the first lattices has a first optical bandgap and each of the second lattices has a second optical bandgap different from the first optical bandgap. A method of fabricating the superlattice doped layers also is disclosed.

Experimental consequences of predicted charge rigidity of superconductors

Energy Technology Data Exchange (ETDEWEB)

Hirsch, J.E., E-mail: jhirsch@ucsd.edu [Department of Physics, University of California, San Diego, La Jolla, CA 92093-0319 (United States)

2012-08-15

The theory of hole superconductivity predicts that in superconductors the charged superfluid is about a million times more rigid than the normal electron fluid. We point out that this physics should give rise to large changes in the bulk and surface plasmon dispersion relations of metals entering the superconducting state, that have not yet been experimentally detected and would be in stark contradiction with the expected behavior within conventional BCS-London theory. We also propose that this explains the puzzling experimental observations of Avramenko et al. on electron sound propagation in superconductors and the puzzling experiments of de Heer et al. detecting large electric dipole moments in small metal clusters, as well as the Tao effect on aggregation of superconducting microparticles in an electric field. Associated with the enhanced charge rigidity is a large increase in the electric screening length of superconductors at low temperatures that has not yet been experimentally detected. The physical origin of the enhanced charge rigidity and its relation to other aspects of the theory of hole superconductivity is discussed.

Large-Scale Structure and Hyperuniformity of Amorphous Ices

Science.gov (United States)

Martelli, Fausto; Torquato, Salvatore; Giovambattista, Nicolas; Car, Roberto

2017-09-01

We investigate the large-scale structure of amorphous ices and transitions between their different forms by quantifying their large-scale density fluctuations. Specifically, we simulate the isothermal compression of low-density amorphous ice (LDA) and hexagonal ice to produce high-density amorphous ice (HDA). Both HDA and LDA are nearly hyperuniform; i.e., they are characterized by an anomalous suppression of large-scale density fluctuations. By contrast, in correspondence with the nonequilibrium phase transitions to HDA, the presence of structural heterogeneities strongly suppresses the hyperuniformity and the system becomes hyposurficial (devoid of "surface-area fluctuations"). Our investigation challenges the largely accepted "frozen-liquid" picture, which views glasses as structurally arrested liquids. Beyond implications for water, our findings enrich our understanding of pressure-induced structural transformations in glasses.

Bang-Bang Practical Stabilization of Rigid Bodies

Science.gov (United States)

Serpelloni, Edoardo

In this thesis, we study the problem of designing a practical stabilizer for a rigid body equipped with a set of actuators generating only constant thrust. Our motivation stems from the fact that modern space missions are required to accurately control the position and orientation of spacecraft actuated by constant-thrust jet-thrusters. To comply with the performance limitations of modern thrusters, we design a feedback controller that does not induce high-frequency switching of the actuators. The proposed controller is hybrid and it asymptotically stabilizes an arbitrarily small compact neighborhood of the target position and orientation of the rigid body. The controller is characterized by a hierarchical structure comprising of two control layers. At the low level of the hierarchy, an attitude controller stabilizes the target orientation of the rigid body. At the high level, after the attitude controller has steered the rigid body sufficiently close to its desired orientation, a position controller stabilizes the desired position. The size of the neighborhood being stabilized by the controller can be adjusted via a proper selection of the controller parameters. This allows us to stabilize the rigid body to virtually any degree of accuracy. It is shown that the controller, even in the presence of measurement noise, does not induce high-frequency switching of the actuators. The key component in the design of the controller is a hybrid stabilizer for the origin of double-integrators affected by bounded external perturbations. Specifically, both the position and the attitude stabilizers consist of multiple copies of such a double-integrator controller. The proposed controller is applied to two realistic spacecraft control problems. First, we apply the position controller to the problem of stabilizing the relative position between two spacecraft flying in formation in the vicinity of the L2 libration point of the Sun-Earth system as a part of a large space telescope

Highly featured amorphous silicon nanorod arrays for high-performance lithium-ion batteries

International Nuclear Information System (INIS)

Soleimani-Amiri, Samaneh; Safiabadi Tali, Seied Ali; Azimi, Soheil; Sanaee, Zeinab; Mohajerzadeh, Shamsoddin

2014-01-01

High aspect-ratio vertical structures of amorphous silicon have been realized using hydrogen-assisted low-density plasma reactive ion etching. Amorphous silicon layers with the thicknesses ranging from 0.5 to 10 μm were deposited using radio frequency plasma enhanced chemical vapor deposition technique. Standard photolithography and nanosphere colloidal lithography were employed to realize ultra-small features of the amorphous silicon. The performance of the patterned amorphous silicon structures as a lithium-ion battery electrode was investigated using galvanostatic charge-discharge tests. The patterned structures showed a superior Li-ion battery performance compared to planar amorphous silicon. Such structures are suitable for high current Li-ion battery applications such as electric vehicles

Highly featured amorphous silicon nanorod arrays for high-performance lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Soleimani-Amiri, Samaneh; Safiabadi Tali, Seied Ali; Azimi, Soheil; Sanaee, Zeinab; Mohajerzadeh, Shamsoddin, E-mail: mohajer@ut.ac.ir [Thin Film and Nanoelectronics Lab, Nanoelectronics Center of Excellence, School of Electrical and Computer Engineering, University of Tehran, Tehran 143957131 (Iran, Islamic Republic of)

2014-11-10

High aspect-ratio vertical structures of amorphous silicon have been realized using hydrogen-assisted low-density plasma reactive ion etching. Amorphous silicon layers with the thicknesses ranging from 0.5 to 10 μm were deposited using radio frequency plasma enhanced chemical vapor deposition technique. Standard photolithography and nanosphere colloidal lithography were employed to realize ultra-small features of the amorphous silicon. The performance of the patterned amorphous silicon structures as a lithium-ion battery electrode was investigated using galvanostatic charge-discharge tests. The patterned structures showed a superior Li-ion battery performance compared to planar amorphous silicon. Such structures are suitable for high current Li-ion battery applications such as electric vehicles.

Amorphous calcium carbonate particles form coral skeletons

Science.gov (United States)

Mass, Tali; Giuffre, Anthony J.; Sun, Chang-Yu; Stifler, Cayla A.; Frazier, Matthew J.; Neder, Maayan; Tamura, Nobumichi; Stan, Camelia V.; Marcus, Matthew A.; Gilbert, Pupa U. P. A.

2017-09-01

Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed “vital effects,” that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO3). We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO2 increases, such as the Paleocene-Eocene Thermal Maximum that occurred 56 Mya.

Evaluation for rigidity of box construction of nuclear reactor building

International Nuclear Information System (INIS)

Yamakawa, Tetsuo

1979-01-01

A huge box-shaped structure (hereafter, called box construction) of reinforced concrete is presently utilized as the reactor building structure in nuclear power plants. Evaluation of the rigidity of the huge box construction is required for making a vibration analysis model of nuclear reactor buildings. It is necessary to handle the box construction as the plates to which the force in plane is applied. This paper describes that the bending theory in elementary beam theory is equivalent to a peculiar, orthogonally anisotropic plate, the shearing rigidity and film rigidity in y direction of which are put to infinity and the Poisson's ratio is put to zero, viewed from the two-dimensional theory of elasticity. The form factor of 1.2 for shearing deformation in rectangular cross section was calculated from the parabolic distribution of shearing stress intensity, and it is the maximum value. The factor is equal to 1.2 for slender beams, but smaller than 1.2 for short and thick beams, having tendency to converge to 1.0. The non-conformity of boundary conditions regarding the shearing force at the both ends of cantilevers does not affect very seriously the evaluation of shearing rigidity. From the above results, it was found that the application of the theory to the box construction was able to give the rigidity evaluation with sufficient engineering accuracy. The theory can also be applied to the evaluation of tube type ultrahigh buildings. (Wakatsuki, Y.)

Polylactide based nanocomposites: Processing, structure and performance relationship

Science.gov (United States)

Karami, Shahir

chains at the temperatures above Tg+60°C. The larger nucleation density resulted in the formation of larger rigid amorphous fraction along the semi-crystalline matrix. The variation of complex viscosity at molten state reflected the degradation of polylactide. The NMR characterization was conducted to investigate the effect of dispersed nanoparticle on the degradation of matrix. It was found that the degradation was accelerated with the nanoparticle content. However, the stereoregularity of polylactide chains remained unchanged in the presence of nanoparticles. Mechanical response was measured using Instron mechanical tester. The fractured surface was analyzed by SEM and SAXS. It was found that, toughness improved with the nanoparticle content due to enhanced occupation density upon multiple crazing. Structural evolutions were investigated during a hot-drawing process, at different initial strain rates and the temperatures of Tg+10°C and Tg+30°C, using WAXS and SAXS offline measurements. A mesomorphic phase was developed along the drawing direction, at Tg+10°C, composed of a bundle of parallel extended molecules with a looser lateral chain packing compared to that of the crystalline domain. The mesophase was disordered at the glass transition temperature of the bulk-like chains acting as the precursor of crystalline ordering. A lower fraction of the intermediate ordering was detected with nanoparticle content than that of the neat polymer at constant processing conditions. The slippage of frozen-in mesophase triggered strain hardening behavior during the stretching process at room temperature. This led to the significant improvement of film toughness and stress at break. Spherulitic crystalline domains were formed upon development of point-like nuclei during the drawing process at T g+30°C. No mesophase was detected at Tg+30°C, due to the enhanced contribution of chain relaxation. Line-like nuclei were observed at the highest applied strain rate, resulting in the

Characterization of the hidden glass transition of amorphous cyclomaltoheptaose.

Science.gov (United States)

Tabary, Nicolas; Mahieu, Aurélien; Willart, Jean-François; Dudognon, Emeline; Danède, Florence; Descamps, Marc; Bacquet, Maryse; Martel, Bernard

2011-10-18

An amorphous solid of cyclomaltoheptaose (β-cyclodextrin, β-CD) was formed by milling its crystalline form using a high-energy planetary mill at room temperature. The glass transition of this amorphous solid was found to occur above the thermal degradation point of the material preventing its direct observation and thus its full characterization. The corresponding glass transition temperature (T(g)) and the ΔC(p) at T(g) have, however, been estimated by extrapolation of T(g) and ΔC(p) of closely related amorphous compounds. These compounds include methylated β-CD with different degrees of substitution and molecular alloys obtained by co-milling β-CD and methylated β-CD (DS 1.8) at different ratios. The physical characterization of the amorphous states have been performed by powder X-ray diffraction and differential scanning calorimetry, while the chemical integrity of β-CD upon milling was checked by NMR spectroscopy and mass spectrometry. Copyright © 2011 Elsevier Ltd. All rights reserved.

Thermodynamically controlled crystallization of glucose pentaacetates from amorphous phase

Energy Technology Data Exchange (ETDEWEB)

Wlodarczyk, P., E-mail: patrykw@imn.gliwice.pl; Hawelek, L.; Hudecki, A.; Kolano-Burian, A. [Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-100 Gliwice (Poland); Wlodarczyk, A. [Department of Animal Histology and Embryology, University of Silesia, ul. Bankowa 9, 40-007 Katowice (Poland)

2016-08-15

The α and β glucose pentaacetates are known sugar derivatives, which can be potentially used as stabilizers of amorphous phase of active ingredients of drugs (API). In the present work, crystallization behavior of equimolar mixture of α and β form in comparison to both pure anomers is revealed. It was shown that despite the same molecular interactions and similar molecular dynamics, crystallization from amorphous phase is significantly suppressed in equimolar mixture. Time dependent X-ray diffraction studies confirmed higher stability of the quenched amorphous equimolar mixture. Its tendency to crystallization is about 10 times lower than for pure anomers. Calorimetric studies revealed that the α and β anomers don’t form solid solutions and have eutectic point for x{sub α} = 0.625. Suppressed crystallization tendency in the mixture is probably caused by the altered thermodynamics of the system. The factors such as difference of free energy between crystalline and amorphous state or altered configurational entropy are probably responsible for the inhibitory effect.

Frictionless contact of a rigid punch indenting a transversely isotropic elastic layer

Directory of Open Access Journals (Sweden)

Rajesh Patra

2016-03-01

Full Text Available This article is concerned with the study of frictionless contact between a rigid punch and a transversely isotropic elastic layer. The rigid punch is assumed to be axially symmetric and is being pressed towards the layer by an applied concentrated load. The layer is resting on a rigid base and is assumed to be ufficiently thick in comparison with the amount of indentation by the rigid punch. The relationship between the applied load $P$ and the contact area is obtained by solving the mathematically formulated problem through use of Hankel transform of different order. Effect of indentation on the distribution of normal stress at the surface as well as the relationship between the applied load and the area of contact have been shown graphically.

Superplastic flow of two-phase ceramics containing rigid inclusions-zirconia/mullite composites

International Nuclear Information System (INIS)

Yoon, C.K.; Chen, I.W.

1990-01-01

A continuum theory for non-newtonian flow of a two-phase composite containing rigid inclusions is presented. It predicts flow suppression by a factor of (1 - V) q , where V is the volume fraction of the rigid inclusion and q depends on the stress exponent and the inclusion shape. Stress concentrations in the rigid inclusion have also been evaluated. As the stress exponent increases, flow suppression is more pronounced even though stress concentration is less severe. To test this theory, superplastic flow of zirconia/mullite composites, in which zirconia is a soft, non-Newtonian super-plastic matrix and mullite is a rigid phase of various size, shape, and amount, is studied. The continuum theory is found to describe the two-phase superplastic flow reasonably well

Improvement of the physicochemical properties of Co-amorphous naproxen-indomethacin by naproxen-sodium

DEFF Research Database (Denmark)

Beyer, Andreas; Grohganz, Holger; Löbmann, Korbinian

2017-01-01

Improvement of the physicochemical properties of amorphous active pharmaceutical ingredients (APIs) applying the concept of co-amorphisation is a promising alternative to the use of polymer glass solutions. In co-amorphous systems, the physical stability and the dissolution rate of the involved c...... or full exchange of naproxen by its sodium salt was performed, which may present a general optimization method to improve co-amorphous systems....... In the present study, it was thus tested if the physicochemical properties of co-amorphous naproxen-indomethacin could be optimized by incorporation of the naproxen sodium into the system. Three different co-amorphous systems in nine different molar ratios were prepared by quench-cooling: naproxen...... components may be improved in comparison to the respective single amorphous phases. However, for the co-amorphous naproxen-indomethacin model system it has been reported that recrystallization could not be prevented for more than 112days regardless of the applied preparation method and blend ratio...

Matrix rigidity regulates cancer cell growth and cellular phenotype.

Directory of Open Access Journals (Sweden)

Robert W Tilghman

2010-09-01

Full Text Available The mechanical properties of the extracellular matrix have an important role in cell growth and differentiation. However, it is unclear as to what extent cancer cells respond to changes in the mechanical properties (rigidity/stiffness of the microenvironment and how this response varies among cancer cell lines.In this study we used a recently developed 96-well plate system that arrays extracellular matrix-conjugated polyacrylamide gels that increase in stiffness by at least 50-fold across the plate. This plate was used to determine how changes in the rigidity of the extracellular matrix modulate the biological properties of tumor cells. The cell lines tested fall into one of two categories based on their proliferation on substrates of differing stiffness: "rigidity dependent" (those which show an increase in cell growth as extracellular rigidity is increased, and "rigidity independent" (those which grow equally on both soft and stiff substrates. Cells which grew poorly on soft gels also showed decreased spreading and migration under these conditions. More importantly, seeding the cell lines into the lungs of nude mice revealed that the ability of cells to grow on soft gels in vitro correlated with their ability to grow in a soft tissue environment in vivo. The lung carcinoma line A549 responded to culture on soft gels by expressing the differentiated epithelial marker E-cadherin and decreasing the expression of the mesenchymal transcription factor Slug.These observations suggest that the mechanical properties of the matrix environment play a significant role in regulating the proliferation and the morphological properties of cancer cells. Further, the multiwell format of the soft-plate assay is a useful and effective adjunct to established 3-dimensional cell culture models.

Matrix Rigidity Regulates Cancer Cell Growth and Cellular Phenotype

Science.gov (United States)

Tilghman, Robert W.; Cowan, Catharine R.; Mih, Justin D.; Koryakina, Yulia; Gioeli, Daniel; Slack-Davis, Jill K.; Blackman, Brett R.; Tschumperlin, Daniel J.; Parsons, J. Thomas

2010-01-01

Background The mechanical properties of the extracellular matrix have an important role in cell growth and differentiation. However, it is unclear as to what extent cancer cells respond to changes in the mechanical properties (rigidity/stiffness) of the microenvironment and how this response varies among cancer cell lines. Methodology/Principal Findings In this study we used a recently developed 96-well plate system that arrays extracellular matrix-conjugated polyacrylamide gels that increase in stiffness by at least 50-fold across the plate. This plate was used to determine how changes in the rigidity of the extracellular matrix modulate the biological properties of tumor cells. The cell lines tested fall into one of two categories based on their proliferation on substrates of differing stiffness: “rigidity dependent” (those which show an increase in cell growth as extracellular rigidity is increased), and “rigidity independent” (those which grow equally on both soft and stiff substrates). Cells which grew poorly on soft gels also showed decreased spreading and migration under these conditions. More importantly, seeding the cell lines into the lungs of nude mice revealed that the ability of cells to grow on soft gels in vitro correlated with their ability to grow in a soft tissue environment in vivo. The lung carcinoma line A549 responded to culture on soft gels by expressing the differentiated epithelial marker E-cadherin and decreasing the expression of the mesenchymal transcription factor Slug. Conclusions/Significance These observations suggest that the mechanical properties of the matrix environment play a significant role in regulating the proliferation and the morphological properties of cancer cells. Further, the multiwell format of the soft-plate assay is a useful and effective adjunct to established 3-dimensional cell culture models. PMID:20886123

Influence of amorphous layers on the thermal conductivity of phononic crystals

Science.gov (United States)

Verdier, Maxime; Lacroix, David; Didenko, Stanislav; Robillard, Jean-François; Lampin, Evelyne; Bah, Thierno-Moussa; Termentzidis, Konstantinos

2018-03-01

The impact of amorphous phases around the holes and at the upper and lower free surfaces on thermal transport in silicon phononic membranes is studied. By means of molecular dynamics and Monte Carlo simulations, we explore the impact of the amorphous phase (oxidation and amorphous silicon), surfaces roughness, and a series of geometric parameters on thermal transport. We show that the crystalline phase drives the phenomena; the two main parameters are (i) the crystalline fraction between two holes and (ii) the crystalline thickness of the membranes. We reveal the hierarchical impact of nanostructurations on the thermal conductivity, namely, from the most resistive to the less resistive: the creation of holes, the amorphous phase around them, and the amorphization of the membranes edges. The surfaces or interfaces perpendicular to the heat flow hinder the thermal conductivity to a much greater extent than those parallel to the heat flow.

A fax-machine amorphous silicon sensor for X-ray detection

Energy Technology Data Exchange (ETDEWEB)

Alberdi, J. [Association EURATOM/CIEMAT, Madrid (Spain); Barcala, J.M. [Association EURATOM/CIEMAT, Madrid (Spain); Chvatchkine, V. [Association EURATOM/CIEMAT, Madrid (Spain); Ioudine, I. [Association EURATOM/CIEMAT, Madrid (Spain); Molinero, A. [Association EURATOM/CIEMAT, Madrid (Spain); Navarrete, J.J. [Association EURATOM/CIEMAT, Madrid (Spain); Yuste, C. [Association EURATOM/CIEMAT, Madrid (Spain)

1996-10-01

Amorphous silicon detectors have been used, basically, as solar cells for energetics applications. As light detectors, linear sensors are used in fax and photocopier machines because they can be built with a large size, low price and have a high radiation hardness. Due to these performances, amorphous silicon detectors have been used as radiation detectors, and, presently, some groups are developing matrix amorphous silicon detectors with built-in electronics for medical X-ray applications. Our group has been working on the design and development of an X-ray image system based on a commercial fax linear amorphous silicon detector. The sensor scans the selected area and detects light produced by the X-ray in a scintillator placed on the sensor. Image-processing software produces a final image with better resolution and definition. (orig.).

Amino acids as co-amorphous excipients for simvastatin and glibenclamide

DEFF Research Database (Denmark)

Laitinen, Riikka; Löbmann, Korbinian; Grohganz, Holger

2014-01-01

to a few drugs and amino acids. To facilitate the rational selection of amino acids, the practical importance of the amino acid coming from the biological target site of the drug (and associated intermolecular interactions) needs to be established. In the present study, the formation of co......-amorphous systems using cryomilling and combinations of two poorly water-soluble drugs (simvastatin and glibenclamide) with the amino acids aspartic acid, lysine, serine, and threonine was investigated. Solid-state characterization with X-ray powder diffraction, differential scanning calorimetry, and Fourier...... in the mixtures. Interestingly, a favorable effect by the excipients on the tautomerism of amorphous glibenclamide in the co-amorphous blends was seen, as the formation of the thermodynamically less stable imidic acid tautomer of glibenclamide was suppressed compared to that of the pure amorphous drug...

Structure-Property Relationships in Amorphous Transparent Conducting Oxides

Science.gov (United States)

Moffitt, Stephanie Lucille

Over the last 20 years a new field of amorphous transparent conducting oxides (a-TCOs) has developed. The amorphous nature of these films makes them well suited for large area applications. In addition, a-TCOs can be made at low temperatures and through solution processing methods. These assets provide promising opportunities to improve applications such as solar cells and back-lit displays where traditional crystalline TCOs are used. In addition, it opens the door for new technological applications including the possibility for transparent, flexible electronics. Despite the recent growth in this field, fundamental understanding of the true nature of conductivity and the amorphous structure in this materials system is still progressing. To develop a greater understanding of a-TCOs, structure-property relationships were developed in the a-IGO and a-IZO systems. From the combination of element-specific local structure studies and liquid quench molecular dynamics simulations it is clear that a degree of structure remains in a-TCOs. By understanding this structure, the effect of gallium on thermal stability, carrier concentration and carrier mobility is understood. The source of charge carriers in a-IZO is identified as oxygen vacancies through the application of in situ Brouwer analysis. The continued development of the Brouwer analysis technique for use in amorphous oxides adds to the available methods for studying defects in amorphous systems. Finally, the foundational knowledge gained from the in-depth study of a-IGO was extended to understand the role of combustion processing and pulsed laser deposition as growth methods for transistors based on a-IGO.

Superconducting and normal properties of metallic amorphous systems

International Nuclear Information System (INIS)

Esquinazi, P.D.

1983-02-01

The superconducting and transport properties (superconducing critical temperature, superconducting critical currents, electric resistivity and thermal conductivity) of the amorphous alloys La 70 Cu 30 and Zr 70 Cu 30 prepared by melt spinning have been investigated. The modification of these properties when, the initial amorphous metals relax to other metastable state under thermal treatment at below crystallization temperatures, have also been studied. (M.E.L.) [es

Determination of the out-of-plane anisotropy contributions (first and second anisotropy terms) in amorphous Nd-Co thin films by micromagnetic numerical simulations

Science.gov (United States)

Alvarez-Prado, L. M.; Cid, R.; Morales, R.; Diaz, J.; Vélez, M.; Rubio, H.; Hierro-Rodriguez, A.; Alameda, J. M.

2018-06-01

Amorphous Nd-Co thin films exhibit stripe shaped periodic magnetic domains with local out-of-plane magnetization components due to their perpendicular magnetic anisotropy. This anisotropy has been quantified in a fairly simple way by reproducing the experimental magnetization curves by means of micromagnetic numerical simulations. The simulations show that the first (K1) and second (K2) anisotropy constants must be used to properly describe the variation of the stripe domains with the in plane applied magnetic field. A strong temperature dependence of both K1 and K2 has been obtained between 10 K and room temperature. This anisotropy behavior is characteristic of two magnetically coupled 3d-4f sublattices with competing anisotropies.

Structure of amorphous sulfur

CSIR Research Space (South Africa)

Eichinger, BE

2001-06-01

Full Text Available The lambda-transition of elemental sulfur occurring at about 159°C has long been associated with the conversion of cyclic S8 rings (c-S8) to amorphous polymer (a-S) via a ring opening polymerization. It is demonstrated, with the use of both density...

Calculating ensemble averaged descriptions of protein rigidity without sampling.

Directory of Open Access Journals (Sweden)

Luis C González

Full Text Available Previous works have demonstrated that protein rigidity is related to thermodynamic stability, especially under conditions that favor formation of native structure. Mechanical network rigidity properties of a single conformation are efficiently calculated using the integer body-bar Pebble Game (PG algorithm. However, thermodynamic properties require averaging over many samples from the ensemble of accessible conformations to accurately account for fluctuations in network topology. We have developed a mean field Virtual Pebble Game (VPG that represents the ensemble of networks by a single effective network. That is, all possible number of distance constraints (or bars that can form between a pair of rigid bodies is replaced by the average number. The resulting effective network is viewed as having weighted edges, where the weight of an edge quantifies its capacity to absorb degrees of freedom. The VPG is interpreted as a flow problem on this effective network, which eliminates the need to sample. Across a nonredundant dataset of 272 protein structures, we apply the VPG to proteins for the first time. Our results show numerically and visually that the rigidity characterizations of the VPG accurately reflect the ensemble averaged [Formula: see text] properties. This result positions the VPG as an efficient alternative to understand the mechanical role that chemical interactions play in maintaining protein stability.

Extracting a Purely Non-rigid Deformation Field of a Single Structure

Science.gov (United States)

Demirci, Stefanie; Manstad-Hulaas, Frode; Navab, Nassir

During endovascular aortic repair (EVAR) treatment, the aortic shape is subject to severe deformation that is imposed by medical instruments such as guide wires, catheters, and the stent graft. The problem definition of deformable registration of images covering the entire abdominal region, however, is highly ill-posed. We present a new method for extracting the deformation of an aneurysmatic aorta. The outline of the procedure includes initial rigid alignment of two abdominal scans, segmentation of abdominal vessel trees, and automatic reduction of their centerline structures to one specified region of interest around the aorta. Our non-rigid registration procedure then only computes local non-rigid deformation and leaves out all remaining global rigid transformations. In order to evaluate our method, experiments for the extraction of aortic deformation fields are conducted on 15 patient datasets from endovascular aortic repair (EVAR) treatment. A visual assessment of the registration results were performed by two vascular surgeons and one interventional radiologist who are all experts in EVAR procedures.

Polyamorphism in Water: Amorphous Ices and their Glassy States

Science.gov (United States)

Amann-Winkel, K.; Boehmer, R.; Fujara, F.; Gainaru, C.; Geil, B.; Loerting, T.

2015-12-01

Water is ubiquitous and of general importance for our environment. But it is also known as the most anomalous liquid. The fundamental origin of the numerous anomalies of water is still under debate. An understanding of these anomalous properties of water is closely linked to an understanding of the phase diagram of the metastable non-crystalline states of ice. The process of pressure induced amorphization of ice was first observed by Mishima et al. [1]. The authors pressurized hexagonal ice at 77 K up to a pressure of 1.6 GPa to form high density amorphous ice (HDA). So far three distinct structural states of amorphous water are known [2], they are called low- (LDA), high- (HDA) and very high density amorphous ice (VHDA). Since the discovery of multiple distinct amorphous states it is controversy discussed whether this phenomenon of polyamorphism at high pressures is connected to the occurrence of more than one supercooled liquid phase [3]. Alternatively, amorphous ices have been suggested to be of nanocrystalline nature, unrelated to liquids. Indeed inelastic X-ray scattering measurements indicate sharp crystal-like phonons in the amorphous ices [4]. In case of LDA the connection to the low-density liquid (LDL) was inferred from several experiments including the observation of a calorimetric glass-to-liquid transition at 136 K and ambient pressure [5]. Recently also the glass transition in HDA was observed at 116 K at ambient pressure [6] and at 140 K at elevated pressure of 1 GPa [7], using calorimetric measurements as well as dielectric spectroscopy. We discuss here the general importance of amorphous ices and their liquid counterparts and present calorimetric and dielectric measurements on LDA and HDA. The good agreement between dielectric and calorimetric results convey for a clearer picture of water's vitrification phenomenon. [1] O. Mishima, L. D. Calvert, and E. Whalley, Nature 314, 76, 1985 [2] D.T. Bowron, J. L. Finney, A. Hallbrucker, et al., J. Chem

Amorphous Computing: A Research Agenda for the Near Future

Czech Academy of Sciences Publication Activity Database

Wiedermann, Jiří

2012-01-01

Roč. 11, č. 1 (2012), s. 59-63 ISSN 1567-7818 R&D Projects: GA ČR GAP202/10/1333 Institutional research plan: CEZ:AV0Z10300504 Keywords : amorphous computing * nano-machines * flying amorphous computer Subject RIV: IN - Informatics, Computer Science Impact factor: 0.683, year: 2012

Radiation damage in amorphous solids - a computer simulation

International Nuclear Information System (INIS)

Chaki, T.K.; Li, J.C.M.

1984-01-01

It is known for crystalline materials that injection of high energy atoms introduces point defects. The nature of defects is not known for amorphous solids. So a molecular dynamic simulation of radiation damage in an amorphous metal was carried out. An amorphous structure of 685 atoms with periodic boundary conditions in all 3 dimensions was equilibrated first. Then one atom on the surface was given a high initial velocity so it was injected inward. Radial temperature distribution around the line of injection was calculated as a function of time. Void distribution and its evolution with time in the direction of injection was calculated by counting the atomic centers in thin slabs perpendicular to the line of injection. The swelling of the whole solid was calculated also. Some results are compared with experiments

Application of the Fourier pseudospectral time-domain method in orthogonal curvilinear coordinates for near-rigid moderately curved surfaces.

Science.gov (United States)

Hornikx, Maarten; Dragna, Didier

2015-07-01

The Fourier pseudospectral time-domain method is an efficient wave-based method to model sound propagation in inhomogeneous media. One of the limitations of the method for atmospheric sound propagation purposes is its restriction to a Cartesian grid, confining it to staircase-like geometries. A transform from the physical coordinate system to the curvilinear coordinate system has been applied to solve more arbitrary geometries. For applicability of this method near the boundaries, the acoustic velocity variables are solved for their curvilinear components. The performance of the curvilinear Fourier pseudospectral method is investigated in free field and for outdoor sound propagation over an impedance strip for various types of shapes. Accuracy is shown to be related to the maximum grid stretching ratio and deformation of the boundary shape and computational efficiency is reduced relative to the smallest grid cell in the physical domain. The applicability of the curvilinear Fourier pseudospectral time-domain method is demonstrated by investigating the effect of sound propagation over a hill in a nocturnal boundary layer. With the proposed method, accurate and efficient results for sound propagation over smoothly varying ground surfaces with high impedances can be obtained.

Diffusive dynamics during the high-to-low density transition in amorphous ice

Science.gov (United States)

Perakis, Fivos; Amann-Winkel, Katrin; Lehmkühler, Felix; Sprung, Michael; Mariedahl, Daniel; Sellberg, Jonas A.; Pathak, Harshad; Späh, Alexander; Cavalca, Filippo; Schlesinger, Daniel; Ricci, Alessandro; Jain, Avni; Massani, Bernhard; Aubree, Flora; Benmore, Chris J.; Loerting, Thomas; Grübel, Gerhard; Pettersson, Lars G. M.; Nilsson, Anders

2017-08-01

Water exists in high- and low-density amorphous ice forms (HDA and LDA), which could correspond to the glassy states of high- (HDL) and low-density liquid (LDL) in the metastable part of the phase diagram. However, the nature of both the glass transition and the high-to-low-density transition are debated and new experimental evidence is needed. Here we combine wide-angle X-ray scattering (WAXS) with X-ray photon-correlation spectroscopy (XPCS) in the small-angle X-ray scattering (SAXS) geometry to probe both the structural and dynamical properties during the high-to-low-density transition in amorphous ice at 1 bar. By analyzing the structure factor and the radial distribution function, the coexistence of two structurally distinct domains is observed at T = 125 K. XPCS probes the dynamics in momentum space, which in the SAXS geometry reflects structural relaxation on the nanometer length scale. The dynamics of HDA are characterized by a slow component with a large time constant, arising from viscoelastic relaxation and stress release from nanometer-sized heterogeneities. Above 110 K a faster, strongly temperature-dependent component appears, with momentum transfer dependence pointing toward nanoscale diffusion. This dynamical component slows down after transition into the low-density form at 130 K, but remains diffusive. The diffusive character of both the high- and low-density forms is discussed among different interpretations and the results are most consistent with the hypothesis of a liquid-liquid transition in the ultraviscous regime.

Study on the substrate-induced crystallisation of amorphous SiC-precursor ceramics. TIB/A; Untersuchungen zur substratinduzierten Kristallisation amorpher SiC-Precursorkeramiken

Energy Technology Data Exchange (ETDEWEB)

Rau, C.

2000-12-01

In the present thesis the crystallization behaviour of amorphous silicon-carbon materials (SiC{sub x}) was studied. The main topic of the experimental studies formed thereby the epitactical crystallization of thin silicon carbide layers on monocrystalline substrates of silicon carbides or silicon. Furthermore by thermolysis of the polymer amorphous SiC{sub x}-powder was obtained.

Amorphous nickel/cobalt tungsten sulfide electrocatalysts for high-efficiency hydrogen evolution reaction

Energy Technology Data Exchange (ETDEWEB)

Yang, Lun [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics and Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Wu, Xinglong, E-mail: hkxlwu@nju.edu.cn [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics and Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Department of Physics, NingBo University, NingBo 315001 (China); Zhu, Xiaoshu [Center for Analysis and Testing, Nanjing Normal University, Nanjing 210093 (China); He, Chengyu; Meng, Ming; Gan, Zhixing [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics and Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2015-06-30

Graphical abstract: - Highlights: • Amorphous nickel/cobalt tungsten sulfides were synthesized by a thermolytic process. • Amorphous NiWS and CoWS could realize hydrogen evolution efficiently. • Ni/Co promotion and annealing alter the porous structure and chemical bonding states. • Active sites on the surface of amorphous WS{sub x} are increased with Ni or Co doping. • Amorphous NiWS and CoWS have immense potentials in water splitting devices. - Abstract: The hydrogen evolution reaction (HER), an appealing solution for future energy supply, requires efficient and inexpensive electrocatalysts with abundant active surface sites. Although crystalline MoS{sub 2} and WS{sub 2} are promising candidates, their activity is dominated by edge sites. Amorphous tungsten sulfide prepared so far lacks the required active sites and its application has thus been hampered. In this work, nickel and cobalt incorporated amorphous tungsten sulfide synthesized by a thermolytic process is demonstrated to enhance the HER efficiency dramatically. The amorphous nickel tungsten sulfide (amorphous NiWS) annealed at 210 °C delivers the best HER performance in this system boasting a Tafel slope of 55 mV per decade and current density of 8.6 mA cm{sup −2} at 250 mV overpotential in a sustained test for 24 h. The introduction of Ni or Co into the catalyst and subsequent thermal treatment alters the porous structure and chemical bonding states thereby increasing the density of active sites on the surface.

Stability of (Fe-Tm-B) amorphous alloys: relaxation and crystallization phenomena

International Nuclear Information System (INIS)

Zemcik, T.

1994-01-01

Fe-Tm-B base (TM = transition metal) amorphous alloys (metallic glasses) are thermodynamically metastable. This limits their use as otherwise favourable materials, e.g. magnetically soft, corrosion resistant and mechanically firm. By analogy of the mechanical strain-stress dependence, at a certain degree of thermal activation the amorphous structure reaches its limiting state where it changes its character and physical properties. Relaxation and early crystallization processes in amorphous alloys, starting already around 100 C, are reviewed involving subsequently stress relief, free volume shrinking, topological and chemical ordering, pre-crystallization phenomena up to partial (primary) crystallization. Two diametrically different examples are demonstrated from among the soft magnetic materials: relaxation and early crystallization processes in the Fe-Co-B metallic glasses and controlled crystallization of amorphous ribbons yielding rather modern nanocrystalline ''Finemet'' alloys where late relaxation and pre-crystallization phenomena overlap when forming extremely dispersive and fine-grained nanocrystals-in-amorphous-sauce structure. Moessbauer spectroscopy seems to be unique for magnetic and phase analysis of such complicated systems. (orig.)

Amorphous silicon cells for the measurement of photosynthetically active radiation; Utilisation des cellules au silicium amorphe pour la mesure du rayonnement photosynthétiquement actif (400-700 nm)

Energy Technology Data Exchange (ETDEWEB)

Chartier, M. [Institut National de la Recherche Agronomique, Thiverval-Grignon (France); Bonchretien, P.; Allirand, J. M.; Gosse, G.

1989-07-01

Numerical simulation and experimental measurements from amorphous silicon cells in comparison with these now used in ecophysiology illustrate the interest of amorphous silicon cells for the measurement of PAR incident, reflected, and transmitted below the canopy [French] La simulation et la confrontation expérimentale ces réponses des cellules au silicium amorphe par rapport à celles des capteurs existants montrent l’intérêt des cellules au silicium amorphe pour la mesure du rayonnement PAR (exprimé en densité de flux de photons) incident, réfléchi et transmis sous un couvert végétal.

Strategic rigidity and foresight for technology adoption among electric utilities

International Nuclear Information System (INIS)

Shah, Arsalan Nisar; Palacios, Miguel; Ruiz, Felipe

2013-01-01

The variation in the adoption of a technology as a major source of competitive advantage has been attributed to the wide-ranging strategic foresight and the integrative capability of a firm. These possible areas of competitive advantage can exist in the periphery of the firm's strategic vision and can get easily blurred as a result of rigidness and can permeate in the decision-making process of the firm. This article explores how electric utility firms with a renewable energy portfolio can become strategically rigid in terms of adoption of newer technologies. The reluctance or delay in the adoption of new technology can be characterized as strategic rigidness, brought upon as a result of a firm's core competence or core capability in the other, more conventional technology arrangement. This paper explores the implications of such rigidness on the performance of a firm and consequently on the energy eco-system. The paper substantiates the results by emphasizing the case of Iberdrola S.A., an incumbent firm as a wind energy developer and its adoption decision behavior. We illustrate that the very routines that create competitive advantage for firms in the electric utility industry are vulnerable as they might also develop as sources of competitive disadvantage, when firms confront environmental change and uncertainty. - Highlights: • Present a firm-level perspective on technology adoption behavior among electric utilities. • Firms with mature technology can become rigid towards newer technologies. • Case study analysis of a major electric utility firm. • Implications of ‘technology rigidness’ on the energy eco-system

Low-energy excitations in amorphous films of silicon and germanium

International Nuclear Information System (INIS)

Liu, X.; Pohl, R.O.

1998-01-01

We present measurements of internal friction and shear modulus of amorphous Si (a-Si) and amorphous Ge (a-Ge) films on double-paddle oscillators at 5500 Hz from 0.5 K up to room temperature. The temperature- independent plateau in internal friction below 10 K, which is common to all amorphous solids, also exists in these films. However, its magnitude is smaller than found for all other amorphous solids studied to date. Furthermore, it depends critically on the deposition methods. For a-Si films, it decreases in the sequence of electron-beam evaporation, sputtering, self-ion implantation, and hot-wire chemical-vapor deposition (HWCVD). Annealing can also reduce the internal friction of the amorphous films considerably. Hydrogenated a-Si with 1 at.% H prepared by HWCVD leads to an internal friction more than two orders of magnitude smaller than observed for all other amorphous solids. The internal friction increases after the hydrogen is removed by effusion. Our results are compared with earlier measurements on a-Si and a-Ge films, none of which had the sensitivity achieved here. The variability of the low-energy tunneling states in the a-Si and a-Ge films may be a consequence of the tetrahedrally bonded covalent continuous random network. The perfection of this network, however, depends critically on the preparation conditions, with hydrogen incorporation playing a particularly important role. copyright 1998 The American Physical Society

Solid State Characterization of Commercial Crystalline and Amorphous Atorvastatin Calcium Samples

OpenAIRE

Shete, Ganesh; Puri, Vibha; Kumar, Lokesh; Bansal, Arvind K.

2010-01-01

Atorvastatin calcium (ATC), an anti-lipid BCS class II drug, is marketed in crystalline and amorphous solid forms. The objective of this study was to perform solid state characterization of commercial crystalline and amorphous ATC drug samples available in the Indian market. Six samples each of crystalline and amorphous ATC were characterized using X-ray powder diffractometry (XRPD), differential scanning calorimetry (DSC), thermogravimetric analysis, Karl Fisher titrimetry, microscopy (hot s...

The effect of rigid and non-rigid connections between implants and teeth on biological and technical complications: a systematic review and a meta-analysis.

Science.gov (United States)

Tsaousoglou, Phoebus; Michalakis, Konstantinos; Kang, Kiho; Weber, Hans-Peter; Sculean, Anton

2017-07-01

To assess survival, as well as technical and biological complication rates of partial fixed dental prostheses (FDPs) supported by implants and teeth. An electronic Medline search was conducted to identify articles, published in dental journals from January 1980 to August 2015, reporting on partial FDPs supported by implants and teeth. The search terms were categorized into four groups comprising the PICO question. Manual searches of published full-text articles and related reviews were also performed. The initial database search produced 3587 relevant titles. Three hundred and eighty-six articles were retrieved for abstract review, while 39 articles were selected for full-text review. A total of 10 studies were selected for inclusion. Overall survival rate for implants ranged between 90% and 100%, after follow-up periods with a mean range of 18-120 months. The survival of the abutment teeth was 94.1-100%, while the prostheses survival was 85-100% for the same time period. The most frequent complications were "periapical lesions" (11.53%). The most frequent technical complication was "porcelain occlusal fracture" (16.6%), followed by "screw loosening" (15%). According to the meta-analysis, no intrusion was noted on the rigid connection group, while five teeth (8.19%) were intruded in the non-rigid connection group [95% CI (0.013-0.151)]. The tooth-implant FDP seems to be a possible alternative to an implant-supported FDP. There is limited evidence that rigid connection between teeth and implants presents better results when compared with the non-rigid one. The major drawback of non-rigidly connected FDPs is tooth intrusion. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Amorphous silicon passivation for 23.3% laser processed back contact solar cells

Science.gov (United States)

Carstens, Kai; Dahlinger, Morris; Hoffmann, Erik; Zapf-Gottwick, Renate; Werner, Jürgen H.

2017-08-01

This paper presents amorphous silicon deposited at temperatures below 200 °C, leading to an excellent passivation layer for boron doped emitter and phosphorus doped back surface field areas in interdigitated back contact solar cells. A higher deposition temperature degrades the passivation of the boron emitter by an increased hydrogen effusion due to lower silicon hydrogen bond energy, proved by hydrogen effusion measurements. The high boron surface doping in crystalline silicon causes a band bending in the amorphous silicon. Under these conditions, at the interface, the intentionally undoped amorphous silicon becomes p-type conducting, with the consequence of an increased dangling bond defect density. For bulk amorphous silicon this effect is described by the defect pool model. We demonstrate, that the defect pool model is also applicable to the interface between amorphous and crystalline silicon. Our simulation shows the shift of the Fermi energy towards the valence band edge to be more pronounced for high temperature deposited amorphous silicon having a small bandgap. Application of optimized amorphous silicon as passivation layer for the boron doped emitter and phosphorus doped back surface field on the rear side of laser processed back contact solar cells, fabricated using four laser processing steps, yields an efficiency of 23.3%.

Rigid pricing and rationally inattentive consumer

Czech Academy of Sciences Publication Activity Database

Matějka, Filip

2010-01-01

Roč. 20, č. 2 (2010), s. 1-40 ISSN 1211-3298 R&D Projects: GA MŠk LC542 Institutional research plan: CEZ:AV0Z70850503 Keywords : rational inattention * nominal rigidity Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/wp/Wp409.pdf

Fabrication of C60/amorphous carbon superlattice structures

International Nuclear Information System (INIS)

Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi

2001-01-01

The nitrogen doping effects in C 60 films by RF plasma source was investigated, and it was found that the nitrogen ion bombardment broke up C 60 molecules and changed them into amorphous carbon. Based on these results, formation of C 60 /amorphous carbon superlattice structure was proposed. The periodic structure of the resulted films was confirmed by XRD measurements, as the preliminary results of fabrication of the superlattice structure

Dimensional Metrology of Non-rigid Parts Without Specialized Inspection Fixtures =

Science.gov (United States)

Sabri, Vahid

Quality control is an important factor for manufacturing companies looking to prosper in an era of globalization, market pressures and technological advances. Functionality and product quality cannot be guaranteed without this important aspect. Manufactured parts have deviations from their nominal (CAD) shape caused by the manufacturing process. Thus, geometric inspection is a very important element in the quality control of mechanical parts. We will focus here on the geometric inspection of non-rigid (flexible) parts which are widely used in the aeronautic and automotive industries. Non-rigid parts can have different forms in a free-state condition compared with their nominal models due to residual stress and gravity loads. To solve this problem, dedicated inspection fixtures are generally used in industry to compensate for the displacement of such parts for simulating the use state in order to perform geometric inspections. These fixtures and the installation and inspection processes are expensive and time-consuming. Our aim in this thesis is therefore to develop an inspection method which eliminates the need for specialized fixtures. This is done by acquiring a point cloud from the part in a free-state condition using a contactless measuring device such as optical scanning and comparing it with the CAD model for the deviation identification. Using a non-rigid registration method and finite element analysis, we numerically inspect the profile of a non-rigid part. To do so, a simulated displacement is performed using an improved definition of displacement boundary conditions for simulating unfixed parts. In addition, we propose a numerical method for dimensional metrology of non-rigid parts in a free-state condition based on the arc length measurement by calculating the geodesic distance using the Fast Marching Method (FMM). In this thesis, we apply our developed methods on industrial non-rigid parts with free-form surfaces simulated with different types of

Ion-induced damage and amorphization in Si

International Nuclear Information System (INIS)

Holland, O.W.; White, C.W.

1990-01-01

Ion-induced damage growth in high-energy, self-ion irradiated Si was studied using electron microscopy and Rutherford backscattering spectroscopy. The results show that there is a marked variation in the rate of damage growth, as well as the damage morphology, along the path of the ion. Near the ion end-of-range (eor), damage increases monotonically with ion fluence until a buried amorphous layer is formed, while damage growth saturates at a low level in the region ahead. The morphology of the damage in the saturated region is shown to consist predominantly of simple defect clusters such as the divacancy. Damage growth remains saturated ahead of the eor until expansion of the buried amorphous layer encroaches into the region. A homogeneous growth model is presented which accounts for damage saturation, and accurately predicts the dose-rate dependence of the saturation level. Modifications of the model are discussed which are needed to account for the rapid growth in the eor region and near the interface of the buried amorphous layer. Two important factors contributing to rapid damage growth are identified. Spatial separation of the Frenkel defect pairs (i.e. interstitials and vacancies) due to the momentum of the interstitials is shown to greatly impact damage growth near the eor, while uniaxial strain in the interfacial region of the amorphous layer is identified as an important factor contributing to growth at that location. 20 refs., 10 figs

Multiscale multiphysics and multidomain models—Flexibility and rigidity

International Nuclear Information System (INIS)

Xia, Kelin; Opron, Kristopher; Wei, Guo-Wei

2013-01-01

The emerging complexity of large macromolecules has led to challenges in their full scale theoretical description and computer simulation. Multiscale multiphysics and multidomain models have been introduced to reduce the number of degrees of freedom while maintaining modeling accuracy and achieving computational efficiency. A total energy functional is constructed to put energies for polar and nonpolar solvation, chemical potential, fluid flow, molecular mechanics, and elastic dynamics on an equal footing. The variational principle is utilized to derive coupled governing equations for the above mentioned multiphysical descriptions. Among these governing equations is the Poisson-Boltzmann equation which describes continuum electrostatics with atomic charges. The present work introduces the theory of continuum elasticity with atomic rigidity (CEWAR). The essence of CEWAR is to formulate the shear modulus as a continuous function of atomic rigidity. As a result, the dynamics complexity of a macromolecular system is separated from its static complexity so that the more time-consuming dynamics is handled with continuum elasticity theory, while the less time-consuming static analysis is pursued with atomic approaches. We propose a simple method, flexibility-rigidity index (FRI), to analyze macromolecular flexibility and rigidity in atomic detail. The construction of FRI relies on the fundamental assumption that protein functions, such as flexibility, rigidity, and energy, are entirely determined by the structure of the protein and its environment, although the structure is in turn determined by all the interactions. As such, the FRI measures the topological connectivity of protein atoms or residues and characterizes the geometric compactness of the protein structure. As a consequence, the FRI does not resort to the interaction Hamiltonian and bypasses matrix diagonalization, which underpins most other flexibility analysis methods. FRI's computational complexity is of O

Public policies targeting labour market rigidities

Directory of Open Access Journals (Sweden)

Andreea Claudia ŞERBAN

2013-02-01

Full Text Available Labour market rigidity becomes an issue of increasing importance under conditions of shocks associated with the economic crisis due to the need to increase the adaptability and responsiveness to them. Thus, labour market policies must be directed towards mitigating rigidities caused by institutional or demographic factors or certain mismatch between demand and supply of education qualifications. This paper highlights the major role of the active labour market policies targeting the increase of labour flexibility, stressing the importance and impact on the ability to adapt quickly and effectively to macroeconomic shocks. Located on a declining trend in the years preceding the crisis, spending on labour market policies increased in 2009 in all the Member States of the European Union. Spending differences are significant between countries, Romania being at the lowest end of the European Union. This requires special attention because the increased adaptability of workers through training, as active measure, is of major importance considering the increased speed of changes in the labour market.

Rigid cohomology over Laurent series fields

CERN Document Server

Lazda, Christopher

2016-01-01

In this monograph, the authors develop a new theory of p-adic cohomology for varieties over Laurent series fields in positive characteristic, based on Berthelot's theory of rigid cohomology. Many major fundamental properties of these cohomology groups are proven, such as finite dimensionality and cohomological descent, as well as interpretations in terms of Monsky-Washnitzer cohomology and Le Stum's overconvergent site. Applications of this new theory to arithmetic questions, such as l-independence and the weight monodromy conjecture, are also discussed. The construction of these cohomology groups, analogous to the Galois representations associated to varieties over local fields in mixed characteristic, fills a major gap in the study of arithmetic cohomology theories over function fields. By extending the scope of existing methods, the results presented here also serve as a first step towards a more general theory of p-adic cohomology over non-perfect ground fields. Rigid Cohomology over Laurent Series Fields...

Joint ESRF-Cecam workshop polymorphous in liquid and amorphous matter

International Nuclear Information System (INIS)

Price, D.L.; Hennet, L.; Krishnan, S.; Sinn, H.; Alp, E.E.; Saboungi, M.L.; Holland-Moritz, D.; Mossa, S.; Tarjus, G.; Trapananti, A.; Di Cicco, A.; Filipponi, A.; Tanaka, H.; Soper, A.K.; Strassle, Th.; Klotz, S.; Hamel, G.; Nelmes, R.J.; Loveday, J.S.; Rousse, G.; Canny, B.; Chervin, J.C.; Saitta, M.; Marek Koza, M.; Schober, H.; Geiger, A.; Brovchenko, I.; Oleinikova, A.; Strassle, T.; Reichert, H.; Jakse, N.; Lebacq, O.; Pasturel, A.; Salmon, P.S.; Martin, R.A.; Massobrio, C.; Poon, W.C.K.; Pham, K.N.; Voigtmann, Th.; Egelhaaf, S.U.; Pusey, P.N.; Petukhov, A.V.; Dolbnya, I.P.; Vroege, G.J.; Lekkerkerker, H.N.W.; Konig, H.; Keen, D.A.; Benedetti, L.R.; Sihachakr, D.; Dewaele, A.; Weck, G.; Crichton, W.; Mezouar, M.; Loubeyre, P.; Shimojo, F.; Ferlat, G.; San Miguel, A.; Xu, H.; Martinez-Garcia, D.; Zuniga, J.; Munoz-Sanjose, V.; Felipponi, A.; Panfilis, S. de; Di Cicco, A.; Guthrie, M.; Tulk, C.A.; Bemore, C.J.; Xu, J.; Yarger, J.L.; Mao, H.K.; Hemley, R.J.

2004-01-01

This workshop is dedicated to new trends in the simulation and experimental studies of liquid and amorphous matter. Particular emphasis is given to polymorphism in equilibrium and under-cooled metastable liquids, glasses and to amorphous network-forming systems. 5 mains sessions over the 3 days have been organized: 1) under-cooled liquid metals, 2) liquid, glassy and amorphous semiconductors, 3) water and related systems, 4) colloids, macro-molecules and biological cells, and 5) state-of-the-art in experimental and theoretical investigations. This document gathers the abstracts of the presentations

Joint ESRF-Cecam workshop polymorphous in liquid and amorphous matter

Energy Technology Data Exchange (ETDEWEB)

Price, D.L.; Hennet, L.; Krishnan, S.; Sinn, H.; Alp, E.E.; Saboungi, M.L.; Holland-Moritz, D.; Mossa, S.; Tarjus, G.; Trapananti, A.; Di Cicco, A.; Filipponi, A.; Tanaka, H.; Soper, A.K.; Strassle, Th.; Klotz, S.; Hamel, G.; Nelmes, R.J.; Loveday, J.S.; Rousse, G.; Canny, B.; Chervin, J.C.; Saitta, M.; Marek Koza, M.; Schober, H.; Geiger, A.; Brovchenko, I.; Oleinikova, A.; Strassle, T.; Reichert, H.; Jakse, N.; Lebacq, O.; Pasturel, A.; Salmon, P.S.; Martin, R.A.; Massobrio, C.; Poon, W.C.K.; Pham, K.N.; Voigtmann, Th.; Egelhaaf, S.U.; Pusey, P.N.; Petukhov, A.V.; Dolbnya, I.P.; Vroege, G.J.; Lekkerkerker, H.N.W.; Konig, H.; Keen, D.A.; Benedetti, L.R.; Sihachakr, D.; Dewaele, A.; Weck, G.; Crichton, W.; Mezouar, M.; Loubeyre, P.; Shimojo, F.; Ferlat, G.; San Miguel, A.; Xu, H.; Martinez-Garcia, D.; Zuniga, J.; Munoz-Sanjose, V.; Felipponi, A.; Panfilis, S. de; Di Cicco, A.; Guthrie, M.; Tulk, C.A.; Bemore, C.J.; Xu, J.; Yarger, J.L.; Mao, H.K.; Hemley, R.J

2004-07-01

This workshop is dedicated to new trends in the simulation and experimental studies of liquid and amorphous matter. Particular emphasis is given to polymorphism in equilibrium and under-cooled metastable liquids, glasses and to amorphous network-forming systems. 5 mains sessions over the 3 days have been organized: 1) under-cooled liquid metals, 2) liquid, glassy and amorphous semiconductors, 3) water and related systems, 4) colloids, macro-molecules and biological cells, and 5) state-of-the-art in experimental and theoretical investigations. This document gathers the abstracts of the presentations.

Deformation-induced amorphization of crystalline particles in a Cu-Ti metallic glass

International Nuclear Information System (INIS)

Kamentzky, E.A.; Askenazy, P.D.; Johnson, W.L.; Tanner, L.E.

1987-01-01

Crystalline particles and grains embedded in Cu 35 Ti 65 glass ribbons have been amorphized by isothermal cold rolling. The structural evolution has been studied by X-ray diffraction and TEM techniques. Initial particle morphologies are spherulitic and spherical, the latter with sizes ranging between 10 and 100 nm. The new amorphous phase seems to nucleate at crystalline-amorphous matrix interfaces. Initially there is a well defined interface between the new and the existing amorphous phases but it disappears as rolling progresses. Crystallites on a nanoscale still present in the final stages of particle amorphization have been observed by convergent beam electron diffraction. After sufficient deformation the consolidated ribbon becomes a completely glassy. A morphological description of the transformation process in terms of crystal destabilization and solid- state particle melting is presented

Influence of variation in molar ratio on co-amorphous drug-amino acid systems

DEFF Research Database (Denmark)

Jensen, Katrine Birgitte Tarp; Larsen, Flemming Hofmann; Löbmann, Korbinian

2016-01-01

Molecular interactions were investigated within four different co-amorphous drug-amino acid systems, namely indomethacin-tryptophan (Ind-Trp), furosemide-tryptophan (Fur-Trp), indomethacin-arginine (Ind-Arg) and furosemide-arginine (Fur-Arg). The co-amorphous systems were prepared by ball milling...... observed in the 50mol% drug (1:1M ratio) mixtures, with the exception of co-amorphous Ind-Arg where the interactions within the 40mol% drug samples appear equally strong. A particularly large deviation between the theoretical and actual Tgs was observed within co-amorphous Ind-Arg and Fur-Arg systems......-amorphous mixture without additional interactions. The modified equation described the Tgs of the co-amorphous Ind-Arg with excess Arg less well indicating possible further interactions; however, the FTIR and ssNMR data did not support the presence of additional intermolecular drug-amino acid interactions....

Quantitative determination of amorphous content in ceramic materials using x-ray powder diffraction

International Nuclear Information System (INIS)

Kuchinski, M.A.; Hubbard, C.R.

1988-01-01

A quantitative technique which employs a modified method of additions approach to analyze for low amorphous content in crystalline matrices was developed and tested. Known amounts of amorphous material are added to the starting powder. The method uses the ratio of a measure of the intensity of the amorphous phase corrected for background to the background corrected intensity of a reference line from a crystalline phase. The amorphous spiking phase must be close in composition to the amorphous phase existing in the analyte. A critical step of the method is to correctly establish the background intensity. A completely crystalline material of similar scattering power was used to establish background intensity

Electron irradiation effects in amorphous antimony thin films obtained by cluster-beam deposition

Energy Technology Data Exchange (ETDEWEB)

Fuchs, G.; Treilleux, M.; Santos Aires, F.; Cabaud, B.; Melinon, P.; Hoareau, A. (Lyon-1 Univ., 69 - Villeurbanne (France))

1991-03-01

In order to understand the differences existing between films obtained with a classical molecular beam deposition (MBD) and the new low-energy cluster beam deposition (LECBD), transmission electron microscopy has been used to characterize the first stages of antimony LECBD. Antimony deposits are discontinuous and amorphous up to 2 nm in thickness. They are formed with isolated amorphous antimony particles surrounded by an amorphous antimony oxide shell. Moreover, under electron beam exposure in the microscope, an amorphous-crystal transformation has been observed in the oxide shell. Electron irradiation induces the formation of a crystallized antimony oxide (Sb{sub 2}O{sub 3}) around the amorphous antimony core. (author).

Studies of pulsed laser melting and rapid solidification using amorphous silicon

International Nuclear Information System (INIS)

Lowndes, D.H.; Wood, R.F.

1984-06-01

Pulsed-laser melting of ion implantation-amorphized silicon layers, and subsequent solidification were studied. Measurements of the onset of melting of amorphous silicon layers and of the duration of melting, and modified melting model calculations demonstrated that the thermal conductivity, K/sub a/, of amorphous silicon is very low (K/sub a/ approx. = 0.02 W/cm-K). K/sub a/ is also the dominant parameter determining the dynamical response of amorphous silicon to pulsed laser radiation. TEM indicates that bulk (volume) nucleation occurs directly from the highly undercooled liquid silicon that can be prepared by pulsed laser melting of amorphous silicon layers at low laser energy densities. A modified thermal melting model is presented. The model calculations demonstrate that the release of latent heat by bulk nucleation occurring during the melt-in process is essential to obtaining agreement with observed depths of melting. These calculations also show that this release of latent heat accompanying bulk nucleation can result in the existence of buried molten layers of silicon in the interior of the sample after the surface has solidified. The bulk nucleation implies that the liquid-to-amorphous phase transition (produced using picosecond or uv nanosecond laser pulses) cannot be explained using purely thermodynamic considerations

Amorphization of Laves-Phase Precipitates in Zircaloy-4 by Neutron Irradiation

Energy Technology Data Exchange (ETDEWEB)

Peters, H.R.; Taylor, D.F.; Yang, Walter J.S.

1999-04-23

Examination of corrosion coupons by transmission electron microscopy after their exposure in the Idaho Advanced Test Reactor (ATR) has broadened the Zircaloy-4 precipitate-amorphization database and validated a new kinetic model for previously unavailable values of temperature and fast-neutron flux. The model describes the amorphization of Zr(Fe,Cr){sub 2} intermetallic precipitates in zirconium alloys as a dynamic competition between radiation damage and thermal annealing that leaves some iron atoms available for flux-assisted diffusion to the zirconium matrix. It predicts the width of the amorphous zone as a function of neutron flux (E>1 MeV), temperature, and time. In its simplest form, the model treats the crystalline/amorphous and precipitate/matrix interfaces as parallel planes, and its accuracy decreases for small precipitates and high fluence as the amorphous-zone width approaches precipitate dimensions. The simplest form of the model also considers diffusion to be rate-determining. This is an accurate approximation for steady-state conditions or slow changes in flux and temperature, but inappropriate for the analysis of faster transients. The paper addresses several difficulties inherent in measuring amorphous-zone width, and utilizes the expanded database to evaluate the improvements in predictive accuracy available through both conversion of the model to spherical coordinates and extension of its time dependency.

H infinity controller design to a rigid-flexible satellite with two vibration modes

International Nuclear Information System (INIS)

De Souza, A G; De Souza, L C G

2015-01-01

The satellite attitude control system (ACS) design becomes more complex when the satellite structure has components like, flexible solar panels, antennas and mechanical manipulators. These flexible structures can interact with the satellite rigid parts during translational and/or rotational manoeuvre damaging the ACS pointing accuracy. Although, a well-designed controller can suppress such disturbances quickly, the controller error pointing may be limited by the minimum time necessary to suppress such disturbances thus affecting the satellite attitude acquisition. This paper deals with the rigid-flexible satellite ACS design using the H infinity method. The rigid-flexible satellite is represented by a beam connected to a central rigid hub at one end and free at the other one. The equations of motions are obtained considering small flexible deformations and the Euler-Bernoulli hypothesis. The results of the simulations have shown that the H-infinity controller was able to control the rigid motion and suppress the vibrations. (paper)

Amorphous Alloy: Promising Precursor to Form Nanoflowerpot

Directory of Open Access Journals (Sweden)

Guo Lan

2014-01-01

Full Text Available Nanoporous copper is fabricated by dealloying the amorphous Ti2Cu alloy in 0.03 M HF electrolyte. The pore and ligament sizes of the nanoporous copper can be readily tailored by controlling the dealloying time. The as-prepared nanoporous copper provides fine and uniform nanoflowerpots to grow highly dispersed Au nanoflowers. The blooming Au nanoflowers in the nanoporous copper flowerpots exhibit both high catalytic activity and stability towards the oxidation of glucose, indicating that the amorphous alloys are ideal precursors to form nanoflowerpot which can grow functional nanoflowers.

Use of beam probes for rigidity calibration of the A1900 fragment separator

Energy Technology Data Exchange (ETDEWEB)

Ginter, T.N. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Farinon, F. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Baumann, T. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Hausmann, M. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Kwan, E.; Naviliat Cuncic, O. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Portillo, M. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Rogers, A.M.; Stetson, J.; Sumithrarachchi, C. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Villari, A.C.C. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Williams, S.J. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States)

2016-06-01

Use of a beam-based approach is presented for establishing a rigidity calibration for the A1900 fragment separator located at the National Superconducting Cyclotron Laboratory. Also presented is why an alternative approach to the rigidity calibration – using detailed field maps of individual magnetic components – is not a feasible basis for deriving an accurate calibration. The level of accuracy achieved for the rigidity calibration is ±0.1%.

Large-deformation and high-strength amorphous porous carbon nanospheres

Science.gov (United States)

Yang, Weizhu; Mao, Shimin; Yang, Jia; Shang, Tao; Song, Hongguang; Mabon, James; Swiech, Wacek; Vance, John R.; Yue, Zhufeng; Dillon, Shen J.; Xu, Hangxun; Xu, Baoxing

2016-04-01

Carbon is one of the most important materials extensively used in industry and our daily life. Crystalline carbon materials such as carbon nanotubes and graphene possess ultrahigh strength and toughness. In contrast, amorphous carbon is known to be very brittle and can sustain little compressive deformation. Inspired by biological shells and honeycomb-like cellular structures in nature, we introduce a class of hybrid structural designs and demonstrate that amorphous porous carbon nanospheres with a thin outer shell can simultaneously achieve high strength and sustain large deformation. The amorphous carbon nanospheres were synthesized via a low-cost, scalable and structure-controllable ultrasonic spray pyrolysis approach using energetic carbon precursors. In situ compression experiments on individual nanospheres show that the amorphous carbon nanospheres with an optimized structure can sustain beyond 50% compressive strain. Both experiments and finite element analyses reveal that the buckling deformation of the outer spherical shell dominates the improvement of strength while the collapse of inner nanoscale pores driven by twisting, rotation, buckling and bending of pore walls contributes to the large deformation.

Production and properties of light-metal base amorphous alloys

International Nuclear Information System (INIS)

Inoue, Akihisa; Masumoto, Tsuyoshi

1993-01-01

Light-metal base alloys with high specific strength and good corrosion resistance were produced through amorphization of Al and Mg-based alloys. The amorphous phase is formed in rapidly solidified Al-TM-Ln and Mg-TM-Ln (TM=transition metal, Ln=lanthanide metal) alloys. The highest tensile strength (σ f ) reaches 1,330 MPa for the Al base and 830 MPa for the Mg base. Furthermore, the Mg-based alloys have a large glass-forming capacity which enables to produce an amorphous phase by a metallic mold casting method. The extrusion of the Al-based amorphous powders at temperatures above crystallization temperature caused the formation of high strength materials with finely mixed structure consisting of dispersed intermetallic compounds in an Al matrix. The highest values of σ f and fatigue limit are as high as 940 and 313 MPa, respectively, at room temperature and 520 and 165 MPa at 473 K. The extruded Al-Ni-Mm alloy has already been used as machine parts and subsequent further development as practical materials is expected by taking these advantages

Superconducting properties of amorphous Zr-Ge binary alloys

International Nuclear Information System (INIS)

Inoue, A.; Takahashi, Y.; Toyota, N.; Fukase, T.; Masumoto, T.

1982-01-01

A new type of refractory metal-metalloid amorphous alloys exhibiting superconductivity has been found in a binary Zr-Ge system by a modified melt-spinning technique. Specimens are in the form of continuous ribbons 1 to 2 mm wide and 0.02 to 0.03 mm thick. The germanium content in the amorphous alloys is limited to the range of 13 to 21 at%. These amorphous alloys are so ductile that no cracks are observed even after closely contacted bending test. Data are reported for various alloy compositions for the Vickers hardness and crystallization temperature, the tensile fracture strength, superconducting transition temperature Tsub(c), upper critical magnetic field, critical current density in the absence of an applied field, upper critical field gradient at Tsub(c) and the electrical resistivity at 4.2 K. The Ginzburg-Landau (GL) parameter and the GL coherence length were estimated to be 72 to 111 and about 7.9 nm, respectively, from these experimental values by using the Ginzburg-Landau-Abrikosov-Gorkov theory and hence it is concluded that the Zr-Ge amorphous alloys are extremely 'soft' type-II superconductor with high degree of dirtiness which possesses the Tsub(c) values higher than zirconium metal, in addition to high strength combined with good ductility. (author)

Amorphous areas in the cytoplasm of Dendrobium tepal cells

Science.gov (United States)

van Doorn, Wouter G.; Kirasak, Kanjana; Ketsa, Saichol

2013-01-01

In Dendrobium flowers some tepal mesophyll cells showed cytoplasmic areas devoid of large organelles. Such amorphous areas comprised up to about 40% of the cross-section of a cell. The areas were not bound by a membrane. The origin of these areas is not known. We show data suggesting that they can be formed from vesicle-like organelles. The data imply that these organelles and other material become degraded inside the cytoplasm. This can be regarded as a form of autophagy. The amorphous areas became surrounded by small vacuoles, vesicles or double membranes. These seemed to merge and thereby sequester the areas. Degradation of the amorphous areas therefore seemed to involve macroautophagy. PMID:23823702

Thermal stability study of crystalline and novel spray-dried amorphous nilotinib hydrochloride.

Science.gov (United States)

Herbrink, Maikel; Vromans, Herman; Schellens, Jan; Beijnen, Jos; Nuijen, Bastiaan

2018-01-30

The thermal characteristics and the thermal degradation of crystalline and amorphous nilotinib hydrochloride (NH) were studied. The spray drying technique was successfully utilized for the amorphization of NH and was evaluated by spectroscopic techniques and differential scanning calorimetry (DSC). The ethanolic spray drying process yielded amorphous NH with a glass transition temperature (T g ) of 147°C. Thermal characterization of the amorphous phase was performed by heat capacity measurements using modulated DSC (mDSC). Thermal degradation was studied by thermogravimetric analysis (TGA). The derived thermodynamic properties of the amorphous NH indicate fragile behaviour and a low crystallization tendency. NH was found to be molecularly stable up to 193°C. After which, the thermal degradation displayed two phases. The values of the thermal degradation parameters were estimated using the Ozawa-Flynn-Wall and Friedman non-isothermal, model-free, isoconversional methods The results indicate the two phases to be single-step reactions. The examination of the physical stability of amorphous NH during storage and at elevated temperatures showed stability at 180°C for at least 5h and at 20-25°C/60% RH for at least 6 months. During these periods, no crystallization was observed. This study is the first to report the thermal characteristics of NH. Additionally, it is also the first to describe the full thermal analysis of a spray-dried amorphous drug. The thermal data may be used in the projection of future production processes and storage conditions of amorphous NH. Copyright © 2017 Elsevier B.V. All rights reserved.

Using Flory-Huggins phase diagrams as a pre-formulation tool for the production of amorphous solid dispersions: a comparison between hot-melt extrusion and spray drying.

Science.gov (United States)

Tian, Yiwei; Caron, Vincent; Jones, David S; Healy, Anne-Marie; Andrews, Gavin P

2014-02-01

Amorphous drug forms provide a useful method of enhancing the dissolution performance of poorly water-soluble drugs; however, they are inherently unstable. In this article, we have used Flory-Huggins theory to predict drug solubility and miscibility in polymer candidates, and used this information to compare spray drying and melt extrusion as processes to manufacture solid dispersions. Solid dispersions were prepared using two different techniques (hot-melt extrusion and spray drying), and characterised using a combination of thermal (thermogravimetric analysis and differential scanning calorimetry), spectroscopic (Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction methods. Spray drying permitted generation of amorphous solid dispersions across a wider drug concentration than melt extrusion. Melt extrusion provided sufficient energy for more intimate mixing to be achieved between drug and polymer, which may improve physical stability. It was also confirmed that stronger drug-polymer interactions might be generated through melt extrusion. Remixing and dissolution of recrystallised felodipine into the polymeric matrices did occur during the modulated differential scanning calorimetry analysis, but the complementary information provided from FTIR confirms that all freshly prepared spray-dried samples were amorphous with the existence of amorphous drug domains within high drug-loaded samples. Using temperature-composition phase diagrams to probe the relevance of temperature and drug composition in specific polymer candidates facilitates polymer screening for the purpose of formulating solid dispersions. © 2013 Royal Pharmaceutical Society.

A beam position monitor using an amorphous magnetic core

International Nuclear Information System (INIS)

Kobayashi, Toshiaki; Ueda, Toru; Yoshida, Yoichi; Kozawa, Takahiro; Uesaka, Mitsuru; Miya, Kenzo; Tagawa, Seiichi; Kobayashi, Hitoshi.

1994-01-01

A beam position monitor for an electron accelerator has been developed by using an amorphous magnetic core. The position is detected by the difference of leakage inductances of four pickup coils wound on the amorphous magnetic core. The accuracy of the beam position monitor is less than 1 mm for the various electron pulses from nanosecond to microsecond. (author)

CREEP-INDUCED STRUCTURAL CHANGES IN Ni-Si-B AMORPHOUS ALLOY

NARCIS (Netherlands)

Jurikova, A.; Miskuf, J.; Csach, K.; Ocelik, V.

The influence of the stress annealing on the reversible structural relaxation of a Ni-Si-B amorphous ribbon was studied. Creep-induced structural changes in the amorphous structure were derived from anisothermal DSC and dilatometric experiments. It is demonstrated that considerable enthalpy and

Wear Resistant Amorphous and Nanocomposite Coatings

Energy Technology Data Exchange (ETDEWEB)

Racek, O

2008-03-26

Glass forming materials (critical cooling rate <10{sup 4}K.s{sup -1}) are promising for their high corrosion and wear resistance. During rapid cooling, the materials form an amorphous structure that transforms to nanocrystalline during a process of devitrification. High hardness (HV 1690) can be achieved through a controlled crystallization. Thermal spray process has been used to apply coatings, which preserves the amorphous/nanocomposite structure due to a high cooling rate of the feedstock particles during the impact on a substrate. Wear properties have been studied with respect to process conditions and feedstock material properties. Application specific properties such as sliding wear resistance have been correlated with laboratory tests based on instrumented indentation and scratch tests.

Preparation and characterization of spray-dried co-amorphous drug-amino acid salts

DEFF Research Database (Denmark)

Jensen, Katrine Birgitte Tarp; Blaabjerg, Lasse Ingerslev; Lenz, Elisabeth

2016-01-01

scale. In this study, spray-drying was investigated as a scale up preparation method for co-amorphous indomethacin (IND)-amino acid mixtures. In addition, the physico-chemical properties of the different co-amorphous systems were investigated with respect to the amino acids' ability towards co...... dissolution behaviour, and physical stability at various storage conditions, were examined. KEY FINDINGS: Results showed that IND could be converted into an amorphous form in combination with the amino acids arginine (ARG), histidine (HIS) and lysine (LYS) by spray-drying. Solid state characterization...... mixtures were physically stable (>10 months) at room temperature and 40°C under dry conditions. Intrinsic dissolution of the co-amorphous mixtures showed an improved dissolution behaviour under intestinal pH conditions for IND-ARG compared with the crystalline and amorphous forms of the drug. On the other...

Role of solution conformation and flexibility of short peptide ligands that bind to the p56(lck) SH2 domain

NARCIS (Netherlands)

Dekker, Frank J; de Mol, Nico J; Bultinck, Patrick; Kemmink, Johan; Hilbers, Hans W; Liskamp, Rob M J; Dekker, Frank

2003-01-01

A general approach in drug design is making ligands more rigid in order to avoid loss in conformational entropy (deltaS(conf)) upon receptor binding. We hypothesized that in the high affinity binding of pYEEI peptide ligands to the p56(lck) SH2 domain this loss in deltaS(conf) might be diminished

Non-rigid connector: The wand to allay the stresses on abutment

OpenAIRE

Banerjee, Saurav; Khongshei, Arlingstone; Gupta, Tapas; Banerjee, Ardhendu

2011-01-01

The use of rigid connectors in 5-unit fixed dental prosthesis with a pier abutment can result in failure of weaker retainer in the long run as the pier abutment acts as a fulcrum. Non-rigid connector placed on the distal aspect of pier seems to reduce potentially excess stress concentration on the pier abutment.

Achievement report for fiscal 1984 on Sunshine Program-entrusted research and development. Research and development of amorphous solar cells (Research on amorphous silicon interface); 1984 nendo amorphous taiyo denchi no kenkyu kaihatsu seika hokokusho. Amorphous silicon no kaimen no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1985-03-01

As for the formation of amorphous semiconductors by photo-CVD (chemical vapor deposition) processes, details are examined of a-Si formed by the excimer laser-excited photo-CVD process, a-SiC formed by the directly excited photo-CVD process, a-SiGe formed by the mercury sensitized reaction photo-CVD process, and {mu}c-Si formed by the mercury-sensitized reaction photo-CVD process. It is then found that all of the said materials are superior to a product of the plasma CVD process in terms of film quality. As for the fabrication of amorphous Si solar cells by a photo-CVD process, a 3-separate-chamber unit is built, in which all the p-, I-, and n-layer are formed by photo-CVD. It is then found that the introduction of a buffer layer into the p/I interface is a powerful tool to enhance efficiency and that the use of the buffer zone brings about an increase of 9% or more in conversion efficiency. In the case of an amorphous solar cell using monosilane, buffer layer introduction results in a conversion efficiency of 9.05%. (NEDO)

Influence of Solvent Composition on the Performance of Spray-Dried Co-Amorphous Formulations

Directory of Open Access Journals (Sweden)

Jaya Mishra

2018-04-01

Full Text Available Ball-milling is usually used to prepare co-amorphous drug–amino acid (AA mixtures. In this study, co-amorphous drug–AA mixtures were produced using spray-drying, a scalable industrially preferred preparation method. The influence of the solvent type and solvent composition was investigated. Mixtures of indomethacin (IND and each of the three AAs arginine, histidine, and lysine were ball-milled and spray-dried at a 1:1 molar ratio, respectively. Spray-drying was performed at different solvent ratios in (a ethanol and water mixtures and (b acetone and water mixtures. Different ratios of these solvents were chosen to study the effect of solvent mixtures on co-amorphous formulation. Residual crystallinity, thermal properties, salt/partial salt formation, and powder dissolution profiles of the IND–AA mixtures were investigated and compared to pure crystalline and amorphous IND. It was found that using spray-drying as a preparation method, all IND–AA mixtures could be successfully converted into the respective co-amorphous forms, irrespective of the type of solvent used, but depending on the solvent mixture ratios. Both ball-milled and spray-dried co-amorphous samples showed an enhanced dissolution rate and maintained supersaturation compared to the crystalline and amorphous IND itself. The spray-dried samples resulting in co-amorphous samples were stable for at least seven months of storage.

Pressure induced Amorphization of Ln1/3(Nb,Ta)O3

International Nuclear Information System (INIS)

Melchior, A.; Noked, O.; Sterer, E.; Shuker, R.

2014-01-01

The research focuses on the phenomenon of pressure induced amorphization (PIA) in Ln1/3MO3, Ln - La,Pr,Nd and M-Nb,Ta. In most pressure induced phase transitions the material changes from a crystalline phase to another crystalline phase. However, if this transition is kinetically hindered, the increased free energy due to the applied pressure will result in a structural collapse to an amorphous intermediate phase. This phenomenon is known as pressure induced amorphization

Rigid particle revisited: Extrinsic curvature yields the Dirac equation

Energy Technology Data Exchange (ETDEWEB)

Deriglazov, Alexei, E-mail: alexei.deriglazov@ufjf.edu.br [Depto. de Matemática, ICE, Universidade Federal de Juiz de Fora, MG (Brazil); Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050 Tomsk, Lenin Ave. 30 (Russian Federation); Nersessian, Armen, E-mail: arnerses@ysu.am [Yerevan State University, 1 Alex Manoogian St., Yerevan 0025 (Armenia); Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050 Tomsk, Lenin Ave. 30 (Russian Federation)

2014-03-01

We reexamine the model of relativistic particle with higher-derivative linear term on the first extrinsic curvature (rigidity). The passage from classical to quantum theory requires a number of rather unexpected steps which we report here. We found that, contrary to common opinion, quantization of the model in terms of so(3.2)-algebra yields massive Dirac equation. -- Highlights: •New way of canonical quantization of relativistic rigid particle is proposed. •Quantization made in terms of so(3.2) angular momentum algebra. •Quantization yields massive Dirac equation.

Topology-Preserving Rigid Transformation of 2D Digital Images.

Science.gov (United States)

Ngo, Phuc; Passat, Nicolas; Kenmochi, Yukiko; Talbot, Hugues

2014-02-01

We provide conditions under which 2D digital images preserve their topological properties under rigid transformations. We consider the two most common digital topology models, namely dual adjacency and well-composedness. This paper leads to the proposal of optimal preprocessing strategies that ensure the topological invariance of images under arbitrary rigid transformations. These results and methods are proved to be valid for various kinds of images (binary, gray-level, label), thus providing generic and efficient tools, which can be used in particular in the context of image registration and warping.

Photoemission studies of amorphous silicon induced by P + ion implantation

Science.gov (United States)

Petö, G.; Kanski, J.

1995-12-01

An amorphous Si layer was formed on a Si (1 0 0) surface by P + implantation at 80 keV. This layer was investigated by means of photoelectron spectroscopy. The resulting spectra are different from earlier spectra on amorphous Si prepared by e-gun evaporation or cathode sputtering. The differences consist of a decreased intensity in the spectral region corresponding to p-states, and appearace of new states at higher binding energy. Qualitativity similar results have been reported for Sb implanted amorphous Ge and the modification seems to be due to the changed short range order.

Tunneling measurements in amorphous layers of superconducting transition metals: molybdenum, vanadium, and niobium

International Nuclear Information System (INIS)

Roll, U.

1981-01-01

Tunneling experiments with amorphous Molybdenum and Vanadium layers are presented, showing no significant increase of the reduced energy gap 2δ(O)/kTsub(c)(δ) compared with the BCS-value, in contrast to all previous measurement on amorphous superconducting materials of simple s-p-metals, showing on enhanced electron-phonon-interaction. This fact may lead to the conclusion that the strong electron-phonon coupling is caused by the amorphous structure of the superconductor. The present results, however, indicate that the strong electron-phonon interaction cannot be explained only ba the amorphous structure of the superconductor. In the measurements of the second derivative d 2 U/dI 2 no phonon-induced structures have been observed for amorphous molybdenum, vanadium and niobium films. Apparently the phonon density of states F(#betta#) of amorphous transition metals has no structure, thus the longitudinal and transverse phonons cannot be identified in the measured (d 2 U/dI 2 )-curves. This particular behaviour of the amorphous transition metals in contrast to the simple s-p-metals may be interpreted by the strongly localized d-electrons. (orig./GG) [de

Method to quantify the delocalization of electronic states in amorphous semiconductors and its application to assessing charge carrier mobility of p -type amorphous oxide semiconductors

Science.gov (United States)

de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

2018-01-01

Amorphous semiconductors are usually characterized by a low charge carrier mobility, essentially related to their lack of long-range order. The development of such material with higher charge carrier mobility is hence challenging. Part of the issue comes from the difficulty encountered by first-principles simulations to evaluate concepts such as the electron effective mass for disordered systems since the absence of periodicity induced by the disorder precludes the use of common concepts derived from condensed matter physics. In this paper, we propose a methodology based on first-principles simulations that partially solves this problem, by quantifying the degree of delocalization of a wave function and of the connectivity between the atomic sites within this electronic state. We validate the robustness of the proposed formalism on crystalline and molecular systems and extend the insights gained to disordered/amorphous InGaZnO4 and Si. We also explore the properties of p -type oxide semiconductor candidates recently reported to have a low effective mass in their crystalline phases [G. Hautier et al., Nat. Commun. 4, 2292 (2013), 10.1038/ncomms3292]. Although in their amorphous phase none of the candidates present a valence band with delocalization properties matching those found in the conduction band of amorphous InGaZnO4, three of the seven analyzed materials show some potential. The most promising candidate, K2Sn2O3 , is expected to possess in its amorphous phase a slightly higher hole mobility than the electron mobility in amorphous silicon.

High density amorphous ice and its phase transition to ice XII

International Nuclear Information System (INIS)

Kohl, I.

2001-07-01

1998 Lobban et al. reported the neutron diffraction data of a new phase of ice, called ice XII, which formed at 260 K on compression of water within the domain of ice V at a pressure of 0.5 GPa. Surprisingly ice XII forms as an incidental product in the preparation of high-density amorphous ice (HDA) on compression of hexagonale ice (ice Ih) at 77 K up to pressures = 1.3 GPa. A decisive experimental detail is the use of an indium container: when compressing ice Ih in a pressure vessel with indium linings, then reproducibly HDA (high density amorphous ice) forms, but without indium randomly scattered relative amounts of ice XII and HDA form. Ice XII forms on compression of ice Ih at 77 K only via HDA, and not directly from ice Ih. Its formation requires a sudden pronounced apparent pressure drop of ca 0.18 GPa at pressures ca 1.1 GPa. These apparent pressure drops can be caused by buildup friction between the piston and the pressure vessel and its sudden release on further compression. I propose that shock-waves generated by apparent pressure drops cause transient local heating and that this induces nucleation and crystal growth. A specific reproducible method to prepare ice XII is heating HDA in a pressure vessel with indium linings at constant pressures (or constant volume). The ice XII (meta-)stability domain extends between ca 158 and 212 K from ca 0.7 to ca 1.5 GPa. DSC (differential scanning calorimetry) and x-ray powder diffraction revealed, that on heating at atmospheric pressure ice XII transforms directly into cubic ice (ice Ic) at 154 K (heating rate 10 K min - 1) and not into an amorphous form before transition to ice Ic. The enthalpy of the ice XII - ice Ic transition is -1.21 ± 0.07 kJ mol -1 . An estimation of the Gibbs free energy at atmospheric pressure and about 140 K results that ice XII is thermodynamically more stable than ice VI. In the heating curve of ice XII a reversible endothermic step can be found at the onset temperature (heating rate

Corrosion resistance of amorphous NiCrZr and NiCrMoZr alloys

International Nuclear Information System (INIS)

Naka, M.; Miyake, M.; Okamoto, I.

1987-01-01

One of the authors has reported that the corrosion resistance of chromium containing amorphous alloys is extremely improved by alloying phosphorus among metalloids. Two factors operate for the improvement of corrosion resistance of the amorphous alloys. First, phosphorus serves for the rapid formation of protective passive film. Second, the compositional and structural homogeneity in amorphous state also account for the formation of protective film. The latter factor has been clearly seen in the high corrosion resistance of CoCrMoZr and CoCrWZr alloys without metalloids. In order to clarify the separately two factors in the corrosion resistance of amorphous alloys, the corrosion resistance of amorphous alloys without metalloids has to be further investigated. This paper also deals with the corrosion resistance and electrochemical behavior of NiCrZr and NiCrMoZr alloys in 1N HCl, and compare them with the corrosion behavior of the crystalline alloys containing the same composition as that of the amorphous alloys

On the nature of amorphous polymorphism of water

OpenAIRE

Koza, Michael Marek; Geil, Burkhard; Winkel, Katrin; Koehler, Christian; Czeschka, Franz; Scheuermann, Marco; Schober, Helmut; Hansen, Thomas

2005-01-01

We report elastic and inelastic neutron scattering experiments on different amorphous ice modifications. It is shown that an amorphous structure (HDA') indiscernible from the high-density phase (HDA), obtained by compression of crystalline ice, can be formed from the very high-density phase (vHDA) as an intermediate stage of the transition of vHDA into its low-density modification (LDA'). Both, HDA and HDA' exhibit comparable small angle scattering signals characterizing them as structures he...

GHz-rate optical parametric amplifier in hydrogenated amorphous silicon

International Nuclear Information System (INIS)

Wang, Ke-Yao; Foster, Amy C

2015-01-01

We demonstrate optical parametric amplification operating at GHz-rates at telecommunications wavelengths using a hydrogenated amorphous silicon waveguide through the nonlinear optical process of four-wave mixing. We investigate how the parametric amplification scales with repetition rate. The ability to achieve amplification at GHz-repetition rates shows hydrogenated amorphous silicon’s potential for telecommunication applications and a GHz-rate optical parametric oscillator. (paper)

Emotional rigidity negatively impacts remission from anxiety and recovery of well-being.

Science.gov (United States)

Wiltgen, Anika; Shepard, Christopher; Smith, Ryan; Fowler, J Christopher

2018-08-15

Emotional rigidity is described in clinical literature as a significant barrier to recovery; however, few there are few empirical measures of the construct. The current study had two aims: Study 1 aimed to identify latent factors that may bear on the construct of emotional rigidity while Study 2 assessed the potential impact of the latent factor(s) on anxiety remission rates and well-being. This study utilized data from 2472 adult inpatients (1176 females and 1296 males) with severe psychopathology. Study 1 utilized exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) to identify latent factors of emotional rigidity. Study 2 utilized hierarchical logistic regression analyses to assess the relationships among emotional rigidity factors and anxiety remission and well-being recovery at discharge. Study 1 yielded a two-factor solution identified in EFA was confirmed with CFA. Factor 1 consisted of neuroticism, experiential avoidance, non-acceptance of emotions, impaired goal-directed behavior, impulse control difficulties and limited access to emotion regulation strategies when experiencing negative emotions. Factor 2 consisted of lack of emotional awareness and lack of emotional clarity when experiencing negative emotions. Results of Study 2 indicated higher scores on Factor 1 was associated with lower remission rates from anxiety and poorer well-being upon discharge. Factor 2 was not predictive of outcome. Emotional rigidity appears to be a latent construct that negatively impacts remission rates from anxiety. Limitations of the present study include its retrospective design, and inefficient methods of assessing emotional rigidity. Copyright © 2018. Published by Elsevier B.V.

Modeling the Flexural Rigidity of Rod Photoreceptors

Science.gov (United States)

Haeri, Mohammad; Knox, Barry E.; Ahmadi, Aphrodite

2013-01-01

In vertebrate eyes, the rod photoreceptor has a modified cilium with an extended cylindrical structure specialized for phototransduction called the outer segment (OS). The OS has numerous stacked membrane disks and can bend or break when subjected to mechanical forces. The OS exhibits axial structural variation, with extended bands composed of a few hundred membrane disks whose thickness is diurnally modulated. Using high-resolution confocal microscopy, we have observed OS flexing and disruption in live transgenic Xenopus rods. Based on the experimental observations, we introduce a coarse-grained model of OS mechanical rigidity using elasticity theory, representing the axial OS banding explicitly via a spring-bead model. We calculate a bending stiffness of ∼105 nN⋅μm2, which is seven orders-of-magnitude larger than that of typical cilia and flagella. This bending stiffness has a quadratic relation to OS radius, so that thinner OS have lower fragility. Furthermore, we find that increasing the spatial frequency of axial OS banding decreases OS rigidity, reducing its fragility. Moreover, the model predicts a tendency for OS to break in bands with higher spring number density, analogous to the experimental observation that transgenic rods tended to break preferentially in bands of high fluorescence. We discuss how pathological alterations of disk membrane properties by mutant proteins may lead to increased OS rigidity and thus increased breakage, ultimately contributing to retinal degeneration. PMID:23442852

Psychological Prices and Price Rigidity in Grocery Retailing: Analysis of German Scanner Data

OpenAIRE

Herrmann, Roland; Moeser, Anke

2005-01-01

A substantial degree of price rigidity has been reported for branded foods in various studies with scanner data. One possible explanation for price rigidity is the existence of psychological pricing points. We analyze to which extent psychological pricing plays a role in grocery retailing and whether it contributes to price rigidity of branded foods in Germany. Psychological pricing defined here as just-below-the-round-figure-pricing is empirically analyzed with scanner data of weekly prices ...

Solid-state amorphization of SmFe3 by hydrogenation

International Nuclear Information System (INIS)

Mueller, K.H.; Kubis, M.; Handstein, A.; Gutfleisch, O.

2000-01-01

Hydrogen-induced amorphization (HIA) has received much attention as a method for the preparation of amorphous compounds since its discovery by Yeh et al. Meanwhile it has been observed for a large number of intermetallic compounds with C15, C23, B8 2 , DO 19 and L1 2 structures. E.G. the C15 Laves-type compounds (MgCu 2 -type structure) of rare earth (R) - transition metal (T) compounds RT 2 show HIA for R = Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er. Aoki et al. postulated that new amorphizing compounds can be expected at high hydrogen pressures. In this work, the structural changes of SmFe 3 (PuNi 3 -type structure) during heating in high hydrogen pressures are reported

Short, intermediate and long range order in amorphous ices

Science.gov (United States)

Martelli, Fausto; Torquato, Salvatore; Giovanbattista, Nicolas; Car, Roberto

Water exhibits polyamorphism, i.e., it exists in more than one amorphous state. The most common forms of glassy water are the low-density amorphous (LDA) and the high-density amorphous (HDA) ices. LDA, the most abundant form of ice in the Universe, transforms into HDA upon isothermal compression. We model the transformation of LDA into HDA under isothermal compression with classical molecular dynamics simulations. We analyze the molecular structures with a recently introduced scalar order metric to measure short and intermediate range order. In addition, we rank the structures by their degree of hyperuniformity, i.e.,the extent to which long range density fluctuations are suppressed. F.M. and R.C. acknowledge support from the Department of Energy (DOE) under Grant No. DE-SC0008626.

Influence of the deposition-induced stress on the magnetic properties of magnetostrictive amorphous (Fe80Co20)80B20 multilayers with orthogonal anisotropy

International Nuclear Information System (INIS)

Gonzalez-Guerrero, Miguel; Prieto, Jose Luis; Sanchez, Pedro; Aroca, Claudio

2007-01-01

In this work, we experimentally justify that the control of the mechanical stress induced during the deposition of sputtered amorphous magnetostrictive (Fe 80 Co 20 ) 80 B 20 allows a custom design of its magnetic properties. FeCoB multilayers have been sputtered on thermal oxide Si substrates with different buffer materials. The crystalline quality and the thermomechanical properties of the buffer layer influence both the coercive and the anisotropy field. Those buffer layers with both high rigidity and poor thermal conductivity do not allow the dissipation of energy of the incoming sputtered material. Therefore, the mechanical stresses related to the deposition process cannot be released, leading to magnetic layers with high easy-axis coercive field and low anisotropy field. This shows that the mechanical stresses accumulated during deposition are a key parameter for the control of coercivity

A Linear Active Disturbance Rejection Control for a Ball and Rigid Triangle System

Directory of Open Access Journals (Sweden)

Carlos Aguilar-Ibanez

2016-01-01

Full Text Available This paper proposes an application of linear flatness control along with active disturbance rejection control (ADRC for the local stabilization and trajectory tracking problems in the underactuated ball and rigid triangle system. To this end, an observer-based linear controller of the ADRC type is designed based on the flat tangent linearization of the system around its corresponding unstable equilibrium rest position. It was accomplished through two decoupled linear extended observers and a single linear output feedback controller, with disturbance cancelation features. The controller guarantees locally exponentially asymptotic stability for the stabilization problem and practical local stability in the solution of the tracking error. An advantage of combining the flatness and the ADRC methods is that it possible to perform online estimates and cancels the undesirable effects of the higher-order nonlinearities discarded by the linearization approximation. Simulation indicates that the proposed controller behaves remarkably well, having an acceptable domain of attraction.

Rigid inclusions-Comparison between analytical and numerical methods

International Nuclear Information System (INIS)

Gomez Perez, R.; Melentijevic, S.

2014-01-01

This paper compares different analytical methods for analysis of rigid inclusions with finite element modeling. First of all, the load transfer in the distribution layer is analyzed for its different thicknesses and different inclusion grids to define the range between results obtained by analytical and numerical methods. The interaction between the soft soil and the inclusion in the estimation of settlements is studied as well. Considering different stiffness of the soft soil, settlements obtained analytical and numerically are compared. The influence of the soft soil modulus of elasticity on the neutral point depth was also performed by finite elements. This depth has a great importance for the definition of the total length of rigid inclusion. (Author)

Amorphous ice. A microporous solid: astrophysical implications

International Nuclear Information System (INIS)

Mayer, E.; Pletzer, R.

1987-01-01

Vapour deposited amorphous ice, investigated by N 2 -adsorption at 77 K, was found to be a microporous solid. Micropore volumes between 0.21 and 0.12 cm 3 /g were determined by comparison plots and Dubinin-Radushkevich plots. Warming of the adsorbent to 113 K caused sintering and reduction of apparent surface area by about an order of magnitude; in the presence of adsorbed gas, large amounts of gas were enclosed in the solid. The influence of micropores on the H 2 recombination rate on amorphous ice in interstellar dust and on adsorption of volatile gases in comets is discussed briefly

Thermal conductivity of sputtered amorphous Ge films

International Nuclear Information System (INIS)

Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka

2014-01-01

We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids

A mechanistic model for radiation-induced crystallization and amorphization in U3Si

International Nuclear Information System (INIS)

Rest, J.

1994-06-01

Radiation-induced amorphization is assessed. A rate-theory model is formulated wherein amorphous clusters are formed by the damage event These clusters are considered centers of expansion (CE), or excess-free-volume zones. Simultaneously, centers of compression (CC) are created in the material. The CCs are local regions of increased density that travel through the material as an elastic (e.g., acoustic) shock wave. The CEs can be annihilated upon contact with CCs (annihilation probability depends on height of the energy barrier), forming either a crystallized region indistinguishable from the host material, or a region with a slight disorientation (recrystallized grain). Recrystallized grains grow by the accumulation of additional CCs. Full amorphization is calculated on the basis of achieving a fuel volume fraction consistent with the close packing of spherical entities. Amorphization of a recrystallized grain is hindered by the grain boundary. Preirradiation of U 3 Si above the critical temperature for amorphization results in of nanometer-size grains. Subsequent reirradiation below the critical temperature shows that the material has developed a resistance to radiation-induced amorphization higher dose needed to amorphize the preirradiated samples than now preirradiated samples. In the model, it is assumed that grain boundaries act as effective defect sinks, and that enhanced defect annihilation is responsible for retarding amorphization at low temperature. The calculations have been validated against data from ion-irradiation experiments with U 3 Si. To obtain additional validation, the model has also been applied to the ion-induced motion of the interface between crystalline and amorphous phases of U 3 Si. Results of this analysis are compared to data and results of calculations for ion bombardment of Si

Effect of hydridation on structure of amorphous and amorphous-crystalline Fe40Ni40B20 and Co70Fe5Si15B10 bands

International Nuclear Information System (INIS)

Il'inskij, A.G.; Brovko, A.P.; Zelinskaya, G.M.; Kosenko, N.S.; Khristenko, T.M.; Kobzenko, G.F.; Shkola, A.A.

1988-01-01

The structure of amorphous and amorphous-crystaliline Fe 40 Ni 40 B 20 and Co 70 Fe 5 Si-1 5 B 10 alloys, exposed to hydridation at different temperatures, is studied by X-ray diffraction technique. The presence of crystalline constituent in amorphous bands was determined on DRON-3 device and by method of small-angle scattering. The experimental data obtained verify, that hydridation does not only prevent the formation of crystalline phases at annealing, but leads, as well, to disappearance of band crystalline constituent in case of its presence

Mechanical instability in non-uniform atomic structure: Application to amorphous metal

International Nuclear Information System (INIS)

Umeno, Yoshitaka; Kitamura, Takayuki; Tagawa, Motoki

2007-01-01

It is important to reveal the deformation of amorphous metal in the atomistic scale level as materials with non-crystal structure have been attracting attention with their prominent functions. In this paper atomistic simulations of tensile deformation of an amorphous model are conducted and local mechanical instability is analyzed to clarify the deformation mechanism of the amorphous structure. Instability causing sharp stress drop is associated with unstable motion of atoms within local region. The size of the region where the unstable atomic motion occurs corresponds to the magnitude of total stress decrease. At instability with large stress decrease the deformation at the onset of the instability propagates to surrounding region, which gives rise to a hysteresis loop in the stress-strain relation. This manifests the microscopic mechanism of the plasticity of amorphous structure

GENERAL THEORY OF THE ROTATION OF THE NON-RIGID EARTH AT THE SECOND ORDER. I. THE RIGID MODEL IN ANDOYER VARIABLES

International Nuclear Information System (INIS)

Getino, J.; Miguel, D.; Escapa, A.

2010-01-01

This paper is the first part of an investigation where we will present an analytical general theory of the rotation of the non-rigid Earth at the second order, which considers the effects of the interaction of the rotation of the Earth with itself, also named as the spin-spin coupling. Here, and as a necessary step in the development of that theory, we derive complete, explicit, analytical formulae of the rigid Earth rotation that account for the second-order rotation-rotation interaction. These expressions are not provided in this form by any current rigid Earth model. Working within the Hamiltonian framework established by Kinoshita, we study the second-order effects arising from the interaction of the main term in the Earth geopotential expansion with itself, and with the complementary term arising when referring the rotational motion to the moving ecliptic. To this aim, we apply a canonical perturbation method to solve analytically the canonical equations at the second order, determining the expressions that provide the nutation-precession, the polar motion, and the length of day. In the case of the motion of the equatorial plane, nutation-precession, we compare our general approach with the particular study for this motion developed by Souchay et al., showing the existence of new terms whose numerical values are within the truncation level of 0.1 μas adopted by those authors. These terms emerge as a consequence of not assuming in this work the same restrictive simplifications taken by Souchay et al. The importance of these additional contributions is that, as the analytical formulae show, they depend on the Earth model considered, in such a way that the fluid core resonance could amplify them significatively when extending this theory to the non-rigid Earth models.

Green waste cooking oil-based rigid polyurethane foam

Science.gov (United States)

Enderus, N. F.; Tahir, S. M.

2017-11-01

Polyurethane is a versatile polymer traditionally prepared using petroleum-based raw material. Petroleum, however, is a non-renewable material and polyurethane produced was found to be non-biodegradable. In quest for a more environmentally friendly alternative, wastecooking oil, a highly abundant domestic waste with easily derivatized structure, is a viable candidate to replace petroleum. In this study,an investigation to determine physical and chemical properties of rigid polyurethane (PU) foam from waste cooking oil (WCO) was carried out. WCO was first adsorbed by using coconut husk activated carbon adsorbent prior to be used for polyol synthesis. The purified WCO was then used to synthesize polyol via transesterification reaction to yield alcohol groups in the WCO chains structure. Finally, the WCO-based polyol was used to prepare rigid PU foam. The optimum formulation for PU formation was found to be 90 polyol: 60 glycerol: 54 water: 40 diethanolamine: 23 diisocyanate. The rigid PU foam has density of 208.4 kg/m3 with maximum compressive strength and capability to receive load at 0.03 MPa and 0.09 kN, respectively. WCO-based PU can potentially be used to replace petroleum-based PU as house construction materials such as insulation panels.

Amorphization of Fe-based alloy via wet mechanical alloying assisted by PCA decomposition

Energy Technology Data Exchange (ETDEWEB)

Neamţu, B.V., E-mail: Bogdan.Neamtu@stm.utcluj.ro [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Chicinaş, H.F.; Marinca, T.F. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Isnard, O. [Université Grenoble Alpes, Institut NEEL, F-38042, Grenoble (France); CNRS, Institut NEEL, 25 rue des martyrs, BP166, F-38042, Grenoble (France); Pană, O. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Street, 400293, Cluj-Napoca (Romania); Chicinaş, I. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania)

2016-11-01

Amorphization of Fe{sub 75}Si{sub 20}B{sub 5} (at.%) alloy has been attempted both by wet and dry mechanical alloying starting from a mixture of elemental powders. Powder amorphization was not achieved even after 140 hours of dry mechanical alloying. Using the same milling parameters, when wet mechanical alloying was used, the powder amorphization was achieved after 40 h of milling. Our assumption regarding the powder amorphization capability enhancement by contamination with carbon was proved by X-ray Photoelectron Spectroscopy (XPS) measurements which revealed the presence of carbon in the chemical composition of the wet mechanically alloyed sample. Using shorter milling times and several process control agents (PCA) (ethanol, oleic acid and benzene) with different carbon content it was proved that the milling duration required for powder amorphization is linked to the carbon content of the PCA. Differential Scanning Calorimetry (DSC), thermomagnetic (TG) and X-ray Diffraction (XRD) measurements performed to the heated samples revealed the fact that, the crystallisation occurs at 488 °C, thus leading to the formation of Fe{sub 3}Si and Fe{sub 2}B. Thermogravimetry measurements performed under H{sub 2} atmosphere, showed the same amount of contamination with C, which is about 2.3 wt%, for the amorphous samples regardless of the type of PCA. Saturation magnetisation of the wet milled samples decreases upon increasing milling time. In the case of the amorphous samples wet milled with benzene up to 20 h and with oleic acid up to 30 h, the saturation magnetisation has roughly the same value, indicating the same degree of contamination. The XRD performed on the samples milled using the same parameters, revealed that powder amorphization can be achieved even via dry milling, just by adding the equivalent amount of elemental C calculated from the TG plots. This proves that in this system by considering the atomic species which can contaminate the powder, they can be

TEM study of amorphous alloys produced by ion implantation

International Nuclear Information System (INIS)

Johnson, E.; Grant, W.A.; Wohlenberg, P.; Hansen, P.; Chadderton, L.T.

1978-01-01

Ion implantation is a technique for introducing foreign elements into surface layers of solids. Ions, as a suitably accelerated beam, penetrate the surface, slow down by collisions with target atoms to produce a doped layer. This non-equilibrium technique can provide a wide range of alloys without the restrictions imposed by equilibrium phase diagrams. This paper reports on the production of some amorphous transition metal-metalloid alloys by implantation. Thinned foils of Ni, Fe and stainless steel were implanted at room temperature with Dy + and P + ions at doses between 10 13 - 10 17 ions/cm 2 at energies of 20 and 40 keV respectively. Transmission electron microscopy and selected area diffraction analysis were used to investigate the implanted specimens. Radial diffracted intensity measurements confirmed the presence of an amorphous implanted layer. The peak positions of the maxima are in good agreement with data for similar alloys produced by conventional techniques. Only certain ion/target combinations produce these amorphous layers. Implantations at doses lower than those needed for amorphization often result in formation of new crystalline phases such as an h.c.p. phase in nickel and a b.c.c. phase in stainless steel. (Auth.)

High pressure synthesis of amorphous TiO2 nanotubes

Directory of Open Access Journals (Sweden)

Quanjun Li

2015-09-01

Full Text Available Amorphous TiO2 nanotubes with diameters of 8-10 nm and length of several nanometers were synthesized by high pressure treatment of anatase TiO2 nanotubes. The structural phase transitions of anatase TiO2 nanotubes were investigated by using in-situ high-pressure synchrotron X-ray diffraction (XRD method. The starting anatase structure is stable up to ∼20GPa, and transforms into a high-density amorphous (HDA form at higher pressure. Pressure-modified high- to low-density transition was observed in the amorphous form upon decompression. The pressure-induced amorphization and polyamorphism are in good agreement with the previous results in ultrafine TiO2 nanoparticles and nanoribbons. The relationship between the LDA form and α-PbO2 phase was revealed by high-resolution transmission electron microscopy (HRTEM study. In addition, the bulk modulus (B0 = 158 GPa of the anatase TiO2 nanotubes is smaller than those of the corresponding bulks and nanoparticles (180-240 GPa. We suggest that the unique open-ended nanotube morphology and nanosize play important roles in the high pressure phase transition of TiO2 nanotubes.

Crystallization kinetics and magnetic properties of FeSiCr amorphous alloy powder cores

Energy Technology Data Exchange (ETDEWEB)

Xu, Hu-ping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Wang, Ru-wu, E-mail: ruwuwang@hotmail.com [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China); College of Materials Science and Metallurgical Engineering, Wuhan University of Science and Technology, Wuhan 430081 (China); Wei, Ding [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Zeng, Chun [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China)

2015-07-01

The crystallization kinetics of FeSiCr amorphous alloy, characterized by the crystallization activation energy, Avrami exponent and frequency factor, was studied by non-isothermal differential scanning calorimetric (DSC) measurements. The crystallization activation energy and frequency factor of amorphous alloy calculated from Augis–Bennett model were 476 kJ/mol and 5.5×10{sup 18} s{sup −1}, respectively. The Avrami exponent n was calculated to be 2.2 from the Johnson–Mehl–Avrami (JMA) equation. Toroid-shaped Fe-base amorphous powder cores were prepared from the commercial FeSiCr amorphous alloy powder and subsequent cold pressing using binder and insulation. The characteristics of FeSiCr amorphous alloy powder and the effects of compaction pressure and insulation content on the magnetic properties, i.e., effective permeability μ{sub e}, quality factor Q and DC-bias properties of FeSiCr amorphous alloy powder cores, were investigated. The FeSiCr amorphous alloy powder cores exhibit a high value of quality factor and a stable permeability in the frequency range up to 1 MHz, showing superior DC-bias properties with a “percent permeability” of more than 82% at H=100 Oe. - Highlights: • The crystallization kinetics of FeSiCr amorphous alloy was investigated. • The FeSiCr powder cores exhibit a high value of Q and a stable permeability. • The FeSiCr powder cores exhibit superior DC-bias properties.

Almost-global tracking for a rigid body with internal rotors

OpenAIRE

Nayak, Aradhana; Banavar, Ravi N.

2017-01-01

Almost-global orientation trajectory tracking for a rigid body with external actuation has been well studied in the literature, and in the geometric setting as well. The tracking control law relies on the fact that a rigid body is a simple mechanical system (SMS) on the $3-$dimensional group of special orthogonal matrices. However, the problem of designing feedback control laws for tracking using internal actuation mechanisms, like rotors or control moment gyros, has received lesser attention...

Mitral stenosis due to pannus overgrowth after rigid ring annuloplasty.

Science.gov (United States)

Oda, Takeshi; Kato, Seiya; Tayama, Eiki; Fukunaga, Shuji; Akashi, Hidetoshi; Aoyagi, Shigeaki

2010-03-01

Although mitral stenosis (MS) due to pannus overgrowth after mitral valve repair for rheumatic mitral regurgitation (MR) is not uncommon, it is extremely rare in relation to non-rheumatic mitral regurgitation. Whilst it has been suggested that the rigid annuloplasty ring induces pannus overgrowth in the same manner as the flexible ring, to date only in cases using the flexible ring has pannus formation been confirmed by a pathological examination after redo surgery. The case is described of a woman who had undergone mitral valve repair using a 28 mm rigid ring three years previously because of non-rheumatic MR, and subsequently suffered from MS due to pannus formation over the annuloplasty ring. To the present authors' knowledge, this is the first report of MS due to pannus formation after mitral valve repair using a rigid annuloplasty ring to treat non-rheumatic MR documented at reoperation.

Authoritarianism, cognitive rigidity, and the processing of ambiguous visual information.

Science.gov (United States)

Duncan, Lauren E; Peterson, Bill E

2014-01-01

Intolerance of ambiguity and cognitive rigidity are unifying aspects of authoritarianism as defined by Adorno, Frenkel-Brunswik, Levinson, and Sanford (1982/1950), who hypothesized that authoritarians view the world in absolute terms (e.g., good or evil). Past studies have documented the relationship between authoritarianism and intolerance of ambiguity and rigidity. Frenkel-Brunswik (1949) hypothesized that this desire for absolutism was rooted in perceptual processes. We present a study with three samples that directly tests the relationship between right wing authoritarianism (RWA) and the processing of ideologically neutral but ambiguous visual stimuli. As hypothesized, in all three samples we found that RWA was related to the slower processing of visual information that required participants to recategorize objects. In a fourth sample, RWA was unrelated to speed of processing visual information that did not require recategorization. Overall, results suggest a relationship between RWA and rigidity in categorization.

Three-dimensional formulation of rigid-flexible multibody systems with flexible beam elements

International Nuclear Information System (INIS)

Garcia-Vallejo, D.; Mayo, J.; Escalona, J. L.; Dominguez, J.

2008-01-01

Multibody systems generally contain solids with appreciable deformations and which decisively influence the dynamics of the system. These solids have to be modeled by means of special formulations for flexible solids. At the same time, other solids are of such a high stiffness that they may be considered rigid, which simplifies their modeling. For these reasons, for a rigid-flexible multibody system, two types of formulations coexist in the equations of the system. Among the different possibilities provided in the literature on the material, the formulation in natural coordinates and the formulation in absolute nodal coordinates are utilized in this paper to model the rigid and flexible solids, respectively. This paper contains a mixed formulation based on the possibility of sharing coordinates between a rigid solid and a flexible solid. The global mass matrix of the system is shown to be constant and, in addition, many of the constraint equations obtained upon utilizing these formulations are linear and can be eliminated

The Role of Configurational Entropy in Amorphous Systems

Directory of Open Access Journals (Sweden)

Kirsten A. Graeser

2010-05-01

Full Text Available Configurational entropy is an important parameter in amorphous systems. It is involved in the thermodynamic considerations, plays an important role in the molecular mobility calculations through its appearance in the Adam-Gibbs equation and provides information on the solubility increase of an amorphous form compared to its crystalline counterpart. This paper presents a calorimetric method which enables the scientist to quickly determine the values for the configurational entropy at any temperature and obtain the maximum of information from these measurements.

Spectroscopic properties of nitrogen doped hydrogenated amorphous carbon films grown by radio frequency plasma-enhanced chemical vapor deposition

International Nuclear Information System (INIS)

Hayashi, Y.; Yu, G.; Rahman, M. M.; Krishna, K. M.; Soga, T.; Jimbo, T.; Umeno, M.

2001-01-01

Nitrogen doped hydrogenated amorphous carbon thin films have been deposited by rf plasma-enhanced chemical vapor deposition using CH 4 as the source of carbon and with different nitrogen flow rates (N 2 /CH 4 gas ratios between 0 and 3), at 300 K. The dependence modifications of the optical and the structural properties on nitrogen incorporation were investigated using different spectroscopic techniques, such as, Raman spectroscopy, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, electron spin resonance (ESR), photoluminescence (PL) and spectroscopic ellipsometry (SE). Raman spectroscopy and IR absorption reveal an increase in sp 2 -bonded carbon or a change in sp 2 domain size with increasing nitrogen flow rate. It is found that the configuration of nitrogen atoms incorporated into an amorphous carbon network gradually changes from nitrogen atoms surrounded by three (σ bonded) to two (π bonded) neighboring carbons with increasing nitrogen flow rate. Tauc optical gap is reduced from 2.6 to 2.0 eV, and the ESR spin density and the peak-to-peak linewidth increase sharply with increasing nitrogen flow rate. Excellent agreement has been found between the measured SE data and modeled spectra, in which an empirical dielectric function of amorphous materials and a linear void distribution along the thickness have been assumed. The influence of nitrogen on the electronic density of states is explained based on the optical properties measured by UV-VIS and PL including nitrogen lone pair band. [copyright] 2001 American Institute of Physics

Development of large area, high efficiency amorphous silicon solar cell

Energy Technology Data Exchange (ETDEWEB)

Yoon, K.S.; Kim, S.; Kim, D.W. [Yu Kong Taedok Institute of Technology (Korea, Republic of)

1996-02-01

The objective of the research is to develop the mass-production technologies of high efficiency amorphous silicon solar cells in order to reduce the costs of solar cells and dissemination of solar cells. Amorphous silicon solar cell is the most promising option of thin film solar cells which are relatively easy to reduce the costs. The final goal of the research is to develop amorphous silicon solar cells having the efficiency of 10%, the ratio of light-induced degradation 15% in the area of 1200 cm{sup 2} and test the cells in the form of 2 Kw grid-connected photovoltaic system. (author) 35 refs., 8 tabs., 67 figs.

Electrical and Magnetic Properties of Binary Amorphous Transition Metal Alloys.