Discrete exterior calculus approach for discretizing Maxwell's equations on face-centered cubic grids for FDTD

Science.gov (United States)

Salmasi, Mahbod; Potter, Michael

2018-07-01

Maxwell's equations are discretized on a Face-Centered Cubic (FCC) lattice instead of a simple cubic as an alternative to the standard Yee method for improvements in numerical dispersion characteristics and grid isotropy of the method. Explicit update equations and numerical dispersion expressions, and the stability criteria are derived. Also, several tools available to the standard Yee method such as PEC/PMC boundary conditions, absorbing boundary conditions, and scattered field formulation are extended to this method as well. A comparison between the FCC and the Yee formulations is made, showing that the FCC method exhibits better dispersion compared to its Yee counterpart. Simulations are provided to demonstrate both the accuracy and grid isotropy improvement of the method.

Nanodefects in ultrahard crystalline cubic boron nitride

International Nuclear Information System (INIS)

Nistor, S. V.; Stefan, M.; Goovaerts, E.; Schoemaker, D.

2002-01-01

Cubic boron nitride (cBN), the second hardest known material after diamond, exhibits high thermal conductivity and an excellent ability to be n or p doped, which makes it a strong candidate for the next generation of high-temperature micro optical and micro electronic devices. According to recent studies, cBN exhibits a better resistance to radiation damage than diamond, which suggests potential applications in extreme radiation environments. Crystalline cBN powders of up to 0.5 mm linear size is obtained in a similar way as diamond, by catalytic conversion of hexagonal BN (hBN) to cBN at even higher pressures (> 5GPa) and temperatures (∼ 1900 K). Considering the essential role played by the nanodefects (point defects and impurities) in determining its physical properties, it is surprising how limited is the amount of published data concerning the properties of nanodefects in this material, especially by Electron Paramagnetic Resonance (EPR) spectroscopy, the most powerful method for identification and characterization of nanodefects in both insulators and semiconductors. This seems to be due mainly to the absence of natural cBN gems and the extreme difficulties in producing even mm 3 sized synthetic crystals. We shall present our recent EPR studies on cBN crystalline powders, performed in a broad temperature range from room temperature (RT) down to 1.2 K on several sorts of large size cBN powder grits of yellow and amber color for industrial applications. Previous multifrequency (9.3 GHz and 95 GHz) EPR studies of brown to black cBN crystallites prepared with excess of boron, resulted in the discovery of two new types of paramagnetic point defects with different spectral properties, called the D1 and D2 centers. Our X(9.3 GHz)-band EPR investigations resulted in the observation in amber cBN crystalline powders of a spectrum with a strong temperature dependence of the lineshape. It was found that for high and low temperatures, respectively, the numerical

Thermodynamics of face-centered-cubic silicon nucleation at the nanoscale from laser ablation

International Nuclear Information System (INIS)

Hu Shengliang; Li Wuhong; Liu Wei; Dong Yingge; Cao Shirui; Yang Jinlong

2011-01-01

The thermodynamic nucleation and the phase transition of the face-centered-cubic structure of Si (fcc-Si) on the nanoscale are performed by taking the effect of nanosize-induced additional pressure on the fcc-Si formation under the conditions generated by laser ablation in liquid into account. The thermodynamic analyses showed that the formation of fcc-Si nanocrystals with sizes of 2-6 nm would take place prior to that of large fcc-Si nanocrystals, and the phase transition probability from diamond-like structure Si (d-Si) to fcc-Si is rather high, up to 10 -3 -10 -2 , under the conditions created by laser ablation of an Si target in water. These theoretical results suggest that laser ablation in liquid would be an effective industrial route to prepare ultrasmall fcc-Si nanocrystals.

Use of the Primitive Unit Cell in Understanding Subtle Features of the Cubic Closest-Packed Structure

Science.gov (United States)

Hawkins, John A.; Rittenhouse, Jeffrey L.; Soper, Linda M.; Rittenhouse, Robert C.

2008-01-01

One of the most important crystal structures adopted by metals is characterized by the "abcabc"...stacking of close-packed layers. This structure is commonly referred to in textbooks as the cubic close-packed (ccp) or face-centered cubic (fcc) structure, since the entire lattice can be generated by replication of a face-centered cubic unit cell…

BFACF-style algorithms for polygons in the body-centered and face-centered cubic lattices

Energy Technology Data Exchange (ETDEWEB)

Janse van Rensburg, E J [Department of Mathematics and Statistics, York University, Toronto, Ontario M3J 1P3 (Canada); Rechnitzer, A, E-mail: rensburg@yorku.ca, E-mail: andrewr@math.ubc.ca [Department of Mathematics, The University of British Columbia, Vancouver V6T 1Z2, British Columbia (Canada)

2011-04-22

In this paper, the elementary moves of the BFACF-algorithm (Aragao de Carvalho and Caracciolo 1983 Phys. Rev. B 27 1635-45, Aragao de Carvalho and Caracciolo 1983 Nucl. Phys. B 215 209-48, Berg and Foester 1981 Phys. Lett. B 106 323-6) for lattice polygons are generalized to elementary moves of BFACF-style algorithms for lattice polygons in the body-centered (BCC) and face-centered (FCC) cubic lattices. We prove that the ergodicity classes of these new elementary moves coincide with the knot types of unrooted polygons in the BCC and FCC lattices and so expand a similar result for the cubic lattice (see Janse van Rensburg and Whittington (1991 J. Phys. A: Math. Gen. 24 5553-67)). Implementations of these algorithms for knotted polygons using the GAS algorithm produce estimates of the minimal length of knotted polygons in the BCC and FCC lattices.

BFACF-style algorithms for polygons in the body-centered and face-centered cubic lattices

Science.gov (United States)

Janse van Rensburg, E. J.; Rechnitzer, A.

2011-04-01

In this paper, the elementary moves of the BFACF-algorithm (Aragão de Carvalho and Caracciolo 1983 Phys. Rev. B 27 1635-45, Aragão de Carvalho and Caracciolo 1983 Nucl. Phys. B 215 209-48, Berg and Foester 1981 Phys. Lett. B 106 323-6) for lattice polygons are generalized to elementary moves of BFACF-style algorithms for lattice polygons in the body-centered (BCC) and face-centered (FCC) cubic lattices. We prove that the ergodicity classes of these new elementary moves coincide with the knot types of unrooted polygons in the BCC and FCC lattices and so expand a similar result for the cubic lattice (see Janse van Rensburg and Whittington (1991 J. Phys. A: Math. Gen. 24 5553-67)). Implementations of these algorithms for knotted polygons using the GAS algorithm produce estimates of the minimal length of knotted polygons in the BCC and FCC lattices.

BFACF-style algorithms for polygons in the body-centered and face-centered cubic lattices

International Nuclear Information System (INIS)

Janse van Rensburg, E J; Rechnitzer, A

2011-01-01

In this paper, the elementary moves of the BFACF-algorithm (Aragao de Carvalho and Caracciolo 1983 Phys. Rev. B 27 1635-45, Aragao de Carvalho and Caracciolo 1983 Nucl. Phys. B 215 209-48, Berg and Foester 1981 Phys. Lett. B 106 323-6) for lattice polygons are generalized to elementary moves of BFACF-style algorithms for lattice polygons in the body-centered (BCC) and face-centered (FCC) cubic lattices. We prove that the ergodicity classes of these new elementary moves coincide with the knot types of unrooted polygons in the BCC and FCC lattices and so expand a similar result for the cubic lattice (see Janse van Rensburg and Whittington (1991 J. Phys. A: Math. Gen. 24 5553-67)). Implementations of these algorithms for knotted polygons using the GAS algorithm produce estimates of the minimal length of knotted polygons in the BCC and FCC lattices.

Microstructure and mechanical properties of bulk highly faulted fcc/hcp nanostructured cobalt microstructures

Energy Technology Data Exchange (ETDEWEB)

Barry, Aliou Hamady [Université Paris 13, Sorbonne Paris Cité, LSPM CNRS UPR 3407, 93430 Villetaneuse (France); Laboratoire Chimie des Matériaux, Département de Chimie, Faculté des Sciences et Technique, Université de Nouakchott (Mauritania, Islamic Republic of); Dirras, Guy, E-mail: dirras@unv-paris13.fr [Université Paris 13, Sorbonne Paris Cité, LSPM CNRS UPR 3407, 93430 Villetaneuse (France); Schoenstein, Frederic; Tétard, Florent; Jouini, Noureddine [Université Paris 13, Sorbonne Paris Cité, LSPM CNRS UPR 3407, 93430 Villetaneuse (France)

2014-05-01

Nanostructured cobalt powders with an average particle size of 50 nm were synthesized using a polyol method and subsequently consolidated by spark plasma sintering (SPS). SPS experiments performed at 650 °C with sintering times ranging from 5 to 45 min under a pressure of 100 MPa, yielded to dense bulk nanostructured cobalt (relative density greater than 97%). X-ray diffraction patterns of the as-prepared powders showed only a face centered cubic (fcc) crystalline phase, whereas the consolidated samples exhibited a mixture of both fcc and hexagonal close packed (hcp) phases. Transmission electron microscopy observations revealed a lamellar substructure with a high density of nanotwins and stacking faults in every grain of the sintered samples. Room temperature compression tests, carried out at a strain rate of 10{sup −3} s{sup −1}, yielded to highest strain to fracture values of up to 5% for sample of holding time of 15 min, which exhibited a yield strength of 1440 MPa, an ultimate strength as high as 1740 MPa and a Young's modulus of 205 GPa. The modulus of elasticity obtained from the nanoindentation tests, ranges from 181 to 218 GPa. The lowest modulus value of 181 GPa was obtained for the sample with the highest sintering time (45 min), which could be related to mass density loss as a consequence of trapped gases releasing. - Highlights: • Co nanopowder (50 nm) was prepared by reduction in polyol medium. • SPS was used to process bulk nanostructured Co specimens. • Microstructures were made of intricate fcc/hcp, along with nanotwins and SFs. • High strengths and moderate compressive ductility were obtained. • Deformation mechanisms related to complex interplay of different length scales.

Tunneling anisotropic magnetoresistance in Co/AIOx/Al tunnel junctions with fcc Co (111) electrodes

NARCIS (Netherlands)

Wang, Kai; Tran, T. Lan Ahn; Brinks, Peter; Brinks, P.; Sanderink, Johannes G.M.; Bolhuis, Thijs; van der Wiel, Wilfred Gerard; de Jong, Machiel Pieter

2013-01-01

Tunneling anisotropic magnetoresistance (TAMR) has been characterized in junctions comprised of face-centered cubic (fcc) Co (111) ferromagnetic electrodes grown epitaxially on sapphire substrates, amorphous AlOx tunnel barriers, and nonmagnetic Al counterelectrodes. Large TAMR ratios have been

Structural and magnetic properties of hcp and fcc Ni nanoparticles

International Nuclear Information System (INIS)

Gong, J.; Wang, L.L.; Liu, Y.; Yang, J.H.; Zong, Z.G.

2008-01-01

The face-centered-cubic (fcc) and hexagonal-close-packed (hcp) Ni nanoparticles were synthesized with citrate by sol-gel method and heat-treating technique. The structure, morphology and magnetic properties of the samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). Our XRD and TEM results suggested that hcp Ni nanoparticles were successfully synthesized when the heating temperature reaches 300 deg. C. With a further increase in temperature to 400 deg. C, a temperature-induced phase transformation of hcp to fcc was observed. Moreover, the VSM results demonstrated the existence of ferromagnetic behavior in the synthesized fcc and hcp Ni nanoparticles. Nevertheless, the magnetic measurement suggested that the magnetic properties in hcp nanoparticles is probably the sum of two contributions: superparamagnetic and ferromagnetic one. The unsaturated magnetization is much smaller than 47.6 emu/g for the fcc nanoparticles obtained at 400 deg. C and 55 emu/g for the bulk material. It was also found that changes of the stress, grain size and crystal structure during heat-treating have significant influences on the magnetic properties of the Ni nanoparticles

The influence of anisotropy on the core structure of Shockley partial dislocations within FCC materials

Science.gov (United States)

Szajewski, B. A.; Hunter, A.; Luscher, D. J.; Beyerlein, I. J.

2018-01-01

Both theoretical and numerical models of dislocations often necessitate the assumption of elastic isotropy to retain analytical tractability in addition to reducing computational load. As dislocation based models evolve towards physically realistic material descriptions, the assumption of elastic isotropy becomes increasingly worthy of examination. We present an analytical dislocation model for calculating the full dissociated core structure of dislocations within anisotropic face centered cubic (FCC) crystals as a function of the degree of material elastic anisotropy, two misfit energy densities on the γ-surface ({γ }{{isf}}, {γ }{{usf}}) and the remaining elastic constants. Our solution is independent of any additional features of the γ-surface. Towards this pursuit, we first demonstrate that the dependence of the anisotropic elasticity tensor on the orientation of the dislocation line within the FCC crystalline lattice is small and may be reasonably neglected for typical materials. With this approximation, explicit analytic solutions for the anisotropic elasticity tensor {B} for both nominally edge and screw dislocations within an FCC crystalline lattice are devised, and employed towards defining a set of effective isotropic elastic constants which reproduce fully anisotropic results, however do not retain the bulk modulus. Conversely, Hill averaged elastic constants which both retain the bulk modulus and reasonably approximate the dislocation core structure are employed within subsequent numerical calculations. We examine a wide range of materials within this study, and the features of each partial dislocation core are sufficiently localized that application of discrete linear elasticity accurately describes the separation of each partial dislocation core. In addition, the local features (the partial dislocation core distribution) are well described by a Peierls-Nabarro dislocation model. We develop a model for the displacement profile which depends upon

A systematic study on the interfacial energy of O-line interfaces in fcc/bcc systems

International Nuclear Information System (INIS)

Dai, Fuzhi; Zhang, Wenzheng

2013-01-01

Habit planes between face-centered cubic (fcc)/body-centered cubic (bcc) phases usually exhibit irrational orientations, which often agree with the O-line criterion. Previously, energy calculation was made to test whether the habit planes were energetically favorable, but the values of the energy were found very sensitive to the initial atomic configuration in an irrationally orientated interface. In this paper, under the O-line condition, simple selection criteria are proposed to define and remove interfacial interstitials and vacancies in the initial atomic configuration. The criteria are proved to be effective in obtaining robust energy results. Interfacial energies of two types of O-line interfaces in fcc/bcc systems are calculated following the criteria. The observed transformation crystallography of precipitates in Ni–Cr and Cu–Cr systems can be explained consistently as the irrational habit plane in each system is associated with the lowest energy O-line interface. (paper)

Simulation of recrystallization textures in FCC materials based on a self consistent model

International Nuclear Information System (INIS)

Bolmaro, R.E; Roatta, A; Fourty, A.L; Signorelli, J.W; Bertinetti, M.A

2004-01-01

The development of re-crystallization textures in FCC polycrystalline materials has been a long lasting scientific problem. The appearance of the so-called cubic component in high stack fault energy laminated FCC materials is not an entirely understood phenomenon. This work approaches the problem using a self- consistent simulation technique of homogenization. The information on first preferential neighbors is used in the model to consider grain boundary energies and intra granular misorientations and to treat the growth of grains and the mobility of the grain boundary. The energies accumulated by deformations are taken as conducting energies of the nucleation and the later growth is statistically governed by the grain boundary energies. The model shows the correct trend for re-crystallization textures obtained from previously simulated deformation textures for high and low stack fault energy FCC materials. The model's topological representation is discussed (CW)

Synthesis of ultrathin face-centered-cubic Au@Pt and Au@Pd core-shell nanoplates from hexagonal-close-packed Au square sheets

KAUST Repository

Fan, Zhanxi

2015-03-17

The synthesis of ultrathin face-centered-cubic (fcc) Au@Pt rhombic nanoplates is reported through the epitaxial growth of Pt on hexagonal-close-packed (hcp) Au square sheets (AuSSs). The Pt-layer growth results in a hcp-to-fcc phase transformation of the AuSSs under ambient conditions. Interestingly, the obtained fcc Au@Pt rhombic nanoplates demonstrate a unique (101)f orientation with the same atomic arrangement extending from the Au core to the Pt shell. Importantly, this method can be extended to the epitaxial growth of Pd on hcp AuSSs, resulting in the unprecedented formation of fcc Au@Pd rhombic nanoplates with (101)f orientation. Additionally, a small amount of fcc (100)f-oriented Au@Pt and Au@Pd square nanoplates are obtained with the Au@Pt and Au@Pd rhombic nanoplates, respectively. We believe that these findings will shed new light on the synthesis of novel noble bimetallic nanostructures. Phase change: Ultrathin Au@Pt and Au@Pd core-shell nanoplates were prepared from Au square sheets. A phase transformation from hexagonal close-packed (hcp) to face-centered cubic (fcc) is observed upon coating the hcp Au square sheets with Pt or Pd under ambient conditions. The prepared fcc Au@Pt and Au@Pd rhombic nanoplates demonstrate unique (101)f orientation (picture shows a typical fcc Au@Pt rhombic nanoplate). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

FCC-ee Overview

CERN Document Server

Zimmermann, F; Benedikt, M; Burkhardt, H; Cerutti, F; Ferrari, A; Gutleber, J; Haerer, B; Holzer, B; Jensen, E; Kersevan, R; Lebrun, P; Martin, R; Mereghetti, A; Osborne, J; Papaphilippou, Y; Schulte, D; Tomas, R; Wenninger, J; Blondel, A; Koratzinos, M; Boscolo, M; Lari, L; Furukawa, K; Ohmi, K; Oide, K; White, S; Bogomyagkov, A; Koop, I; Levichev, E; Muchnoi, N; Nikitin, S; Shatilov, D; Wienands, U; Gianfelice, E; Medina, L

2015-01-01

The FCC-ee is a proposed circular e+e- collider installed in a new 100 km tunnel delivering high luminosity to four experiments at centre-of-mass energies ranging from 91 GeV (Z pole) over 160 GeV (W threshold) and 240 GeV (H production) to 350 GeV (t physics). The FCC-ee design is pursued as part of the global Future Circular Collider (FCC) study, which regards the FCC-ee as a potential intermediate step towards a 100-TeV hadron collider, called FCC-hh, sharing the same tunnel infrastructure. We here report the FCC-ee design status.

Temperature dependence of critical resolved shear stress for cubic metals

International Nuclear Information System (INIS)

Rashid, H.; Fazal-e-Aleem; Ali, M.

1996-01-01

The experimental measurements for critical resolved shear stress of various BCC and FCC metals have been explained by using Radiation Model. The temperature dependence of CRSS for different cubic metals is found to the first approximation, to upon the type of the crystal. A good agreement between experimental observations and predictions of the Radiation Model is found. (author)

Bcc and Fcc transition metals and alloys: a central role for the Jahn-Teller effect in explaining their ideal and distorted structures.

Science.gov (United States)

Lee, Stephen; Hoffmann, Roald

2002-05-01

Transition metal elements, alloys, and intermetallic compounds often adopt the body centered cubic (bcc) and face centered cubic (fcc) structures. By comparing quantitative density functional with qualitative tight-binding calculations, we analyze the electronic factors which make the bcc and fcc structures energetically favorable. To do so, we develop a tight-binding function, DeltaE(star), a function that measures the energetic effects of transferring electrons within wave vector stars. This function allows one to connect distortions in solids to the Jahn-Teller effect in molecules and to provide an orbital perspective on structure determining deformations in alloys. We illustrate its use by considering first a two-dimensional square net. We then turn to three-dimensional fcc and bcc structures, and distortions of these. Using DeltaE(star), we rationalize the differences in energy of these structures. We are able to deduce which orbitals are responsible for instabilities in seven to nine valence electron per atom (e(-)/a) bcc systems and five and six e(-)/a fcc structures. Finally we demonstrate that these results account for the bcc and fcc type structures found in both the elements and binary intermetallic compounds of group 4 through 9 transition metal atoms. The outline of a theory of metal structure deformations based on loss of point group operation rather than translational symmetry is presented.

Influence of face-centered-cubic texturing of Co2Fe6B2 pinned layer on tunneling magnetoresistance ratio decrease in Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd](n)-SyAF layer.

Science.gov (United States)

Takemura, Yasutaka; Lee, Du-Yeong; Lee, Seung-Eun; Chae, Kyo-Suk; Shim, Tae-Hun; Lian, Guoda; Kim, Moon; Park, Jea-Gun

2015-05-15

The TMR ratio of Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd]n-SyAF layer decreased rapidly when the ex situ magnetic annealing temperature (Tex) was increased from 275 to 325 °C, and this decrease was associated with degradation of the Co2Fe6B2 pinned layer rather than the Co2Fe6B2 free layer. At a Tex above 325 °C the amorphous Co2Fe6B2 pinned layer was transformed into a face-centered-cubic (fcc) crystalline layer textured from [Co/Pd]n-SyAF, abruptly reducing the Δ1 coherence tunneling of perpendicular-spin-torque electrons between the (100) MgO tunneling barrier and the fcc Co2Fe6B2 pinned layer.

The influence of additions of Al and Si on the lattice stability of fcc and hcp Fe-Mn random alloys

Energy Technology Data Exchange (ETDEWEB)

Gebhardt, T; Music, D; Schneider, J M [Materials Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Ekholm, M; Abrikosov, I A [Department of Physics, Chemistry and Biology (IFM), Linkoeping University, SE-58183 Linkoeping (Sweden); Vitos, L [Department of Materials and Engineering, Applied Materials Physics, Royal Institute of Technology (KTH), SE-10044 Stockholm (Sweden); Dick, A; Hickel, T; Neugebauer, J, E-mail: gebhardt@mch.rwth-aachen.de [Department of Computational Materials Design, Max-Planck-Institut fuer Eisenforschung GmbH, D-40237 Duesseldorf (Germany)

2011-06-22

We have studied the influence of additions of Al and Si on the lattice stability of face-centred-cubic (fcc) versus hexagonal-closed-packed (hcp) Fe-Mn random alloys, considering the influence of magnetism below and above the fcc Neel temperature. Employing two different ab initio approaches with respect to basis sets and treatment of magnetic and chemical disorder, we are able to quantify the predictive power of the ab initio methods. We find that the addition of Al strongly stabilizes the fcc lattice independent of the regarded magnetic states. For Si a much stronger dependence on magnetism is observed. Compared to Al, almost no volume change is observed as Si is added to Fe-Mn, indicating that the electronic contributions are responsible for stabilization/destabilization of the fcc phase.

The influence of additions of Al and Si on the lattice stability of fcc and hcp Fe-Mn random alloys

International Nuclear Information System (INIS)

Gebhardt, T; Music, D; Schneider, J M; Ekholm, M; Abrikosov, I A; Vitos, L; Dick, A; Hickel, T; Neugebauer, J

2011-01-01

We have studied the influence of additions of Al and Si on the lattice stability of face-centred-cubic (fcc) versus hexagonal-closed-packed (hcp) Fe-Mn random alloys, considering the influence of magnetism below and above the fcc Neel temperature. Employing two different ab initio approaches with respect to basis sets and treatment of magnetic and chemical disorder, we are able to quantify the predictive power of the ab initio methods. We find that the addition of Al strongly stabilizes the fcc lattice independent of the regarded magnetic states. For Si a much stronger dependence on magnetism is observed. Compared to Al, almost no volume change is observed as Si is added to Fe-Mn, indicating that the electronic contributions are responsible for stabilization/destabilization of the fcc phase.

Structural properties of pure and Fe-doped Yb films prepared by vapor condensation

Energy Technology Data Exchange (ETDEWEB)

Rojas-Ayala, C., E-mail: chachi@cbpf.br [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180, RJ (Brazil); Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Lima, P.O.B. 14-149, Lima 14 (Peru); Passamani, E.C. [Departamento de Física, Universidade Federal do Espírito Santo, Vitória 29075-910, ES (Brazil); Suguihiro, N.M. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180, RJ (Brazil); Litterst, F.J. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180, RJ (Brazil); Institut für Physik der Kondensierten Materie, Technische Universität Braunschweig, 38106 Braunschweig (Germany); Baggio Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180, RJ (Brazil)

2014-10-15

Ytterbium and iron-doped ytterbium films were prepared by vapor quenching on Kapton substrates at room temperature. Structural characterization was performed by X-ray diffraction and transmission electron microscopy. The aim was to study the microstructure of pure and iron-doped films and thereby to understand the effects induced by iron incorporation. A coexistence of face centered cubic and hexagonal close packed-like structures was observed, the cubic-type structure being the dominant contribution. There is an apparent thickness dependence of the cubic/hexagonal relative ratios in the case of pure ytterbium. Iron-clusters induce a crystalline texture effect, but do not influence the cubic/hexagonal volume fraction. A schematic model is proposed for the microstructure of un-doped and iron-doped films including the cubic- and hexagonal-like structures, as well as the iron distribution in the ytterbium matrix. - Highlights: • Pure and Fe-doped Yb films have been prepared by vapor condensation. • Coexistence of fcc- and hcp-type structures was observed. • No oxide phases have been detected. • Fe-clustering does not affect the fcc/hcp ratio, but favors a crystalline texture. • A schematic model is proposed to describe microscopically the microstructure.

Microscopy evidence of the face-centered cubic arrangement of monodisperse polystyrene nanospheres

Energy Technology Data Exchange (ETDEWEB)

Zhang Hui [School of Science, Beijing Jiaotong University, Beijing 100044 (China)]. E-mail: zhanghui14305@sohu.com; Duan Renguan [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Li Fan [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Tang Qing [Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080 (China); Li Wenchao [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

2007-07-01

This paper reports a scanning electron microscopy (SEM) investigation of polystyrene artificial opal achieved through self-assembly of monodisperse polystyrene nanospheres with a diameter of 250 nm from colloidal suspension after being ambient dried. A detailed analysis of the SEM images verifies that the face-centered cubic (fcc) phase is the most stable one for the polystyrene opal prepared. This finding provides a strong support for, by using polystyrene opal as template, fabricating a photonic crystal with inverse fcc structure of full band gap if the refractive index contrast is higher than 2.8 and the filling fraction of the high index materials is between 0.2 and 0.3.

Microscopy evidence of the face-centered cubic arrangement of monodisperse polystyrene nanospheres

International Nuclear Information System (INIS)

Zhang Hui; Duan Renguan; Li Fan; Tang Qing; Li Wenchao

2007-01-01

This paper reports a scanning electron microscopy (SEM) investigation of polystyrene artificial opal achieved through self-assembly of monodisperse polystyrene nanospheres with a diameter of 250 nm from colloidal suspension after being ambient dried. A detailed analysis of the SEM images verifies that the face-centered cubic (fcc) phase is the most stable one for the polystyrene opal prepared. This finding provides a strong support for, by using polystyrene opal as template, fabricating a photonic crystal with inverse fcc structure of full band gap if the refractive index contrast is higher than 2.8 and the filling fraction of the high index materials is between 0.2 and 0.3

FCC 5 and FCC 6 (3/4)

CERN Multimedia

CERN. Geneva; Schulte, Daniel

2016-01-01

Abstract: The electron-positron collider, FCC-ee, should provide collisions over a wide range of beam energies, ranging from roughly 35 GeV to almost 200 GeV. The physics goals of the FCC-ee collider call for luminosities around 1e36 cm-2s-1 per interaction point at the Z pole and several 1e34 cm-2s-1 at the ZH production peak. The beam energy should be pushed above 175 GeV, with a total synchrotron-radiation power not exceeding 100 MW. The extremely high luminosities and resulting short beam lifetime, due to radiative Bhabha scattering, can be sustained by top-up injection. The FCC-ee acce...

High-Pressure Geophysical Properties of Fcc Phase FeHX

Science.gov (United States)

Thompson, E. C.; Davis, A. H.; Bi, W.; Zhao, J.; Alp, E. E.; Zhang, D.; Greenberg, E.; Prakapenka, V. B.; Campbell, A. J.

2018-01-01

Face centered cubic (fcc) FeHX was synthesized at pressures of 18-68 GPa and temperatures exceeding 1,500 K. Thermally quenched samples were evaluated using synchrotron X-ray diffraction (XRD) and nuclear resonant inelastic X-ray scattering (NRIXS) to determine sample composition and sound velocities to 82 GPa. To aid in the interpretation of nonideal (X ≠ 1) stoichiometries, two equations of state for fcc FeHX were developed, combining an empirical equation of state for iron with two distinct synthetic compression curves for interstitial hydrogen. Matching the density deficit of the Earth's core using these equations of state requires 0.8-1.1 wt % hydrogen at the core-mantle boundary and 0.2-0.3 wt % hydrogen at the interface of the inner and outer cores. Furthermore, a comparison of Preliminary Reference Earth Model (PREM) to a Birch's law extrapolation of our experimental results suggests that an iron alloy containing ˜0.8-1.3 wt % hydrogen could reproduce both the density and compressional velocity (VP) of the Earth's outer core.

Microstructurally Based Prediction of High Strain Failure Modes in Crystalline Solids

Science.gov (United States)

2016-07-05

interfaces in hcp– fcc systems subjected to high strain-rate deformation and fracture modes, Journal of Materials Research, (8 2015): 0. doi: 10.1557/jmr...rupture • Comparison and validation with experimental observations/ measurements • New dislocation-density crystalline plasticity that accounts for...relationships between coherent interfaces in hcp– fcc systems subjected to high strain-rate deformation and fracture modes, Journal of Materials Research, Vol. 30

Principal spectra describing magnetooptic permittivity tensor in cubic crystals

Energy Technology Data Exchange (ETDEWEB)

Hamrlová, Jana [Nanotechnology Centre, VSB – Technical University of Ostrava, listopadu 15, Ostrava, 708 33 Czech Republic (Czech Republic); IT4Innovations Centre, VSB – Technical University of Ostrava, listopadu 15, Ostrava, 708 33 Czech Republic (Czech Republic); Legut, Dominik [IT4Innovations Centre, VSB – Technical University of Ostrava, listopadu 15, Ostrava, 708 33 Czech Republic (Czech Republic); Veis, Martin [Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, Prague, 121 16 Czech Republic (Czech Republic); Pištora, Jaromír [Nanotechnology Centre, VSB – Technical University of Ostrava, listopadu 15, Ostrava, 708 33 Czech Republic (Czech Republic); Hamrle, Jaroslav, E-mail: jaroslav.hamrle@vsb.cz [IT4Innovations Centre, VSB – Technical University of Ostrava, listopadu 15, Ostrava, 708 33 Czech Republic (Czech Republic); Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, Prague, 121 16 Czech Republic (Czech Republic); Department of Physics, VSB – Technical University of Ostrava, 17. listopadu 15, Ostrava, 708 33 Czech Republic (Czech Republic)

2016-12-15

We provide unified phenomenological description of magnetooptic effects being linear and quadratic in magnetization. The description is based on few principal spectra, describing elements of permittivity tensor up to the second order in magnetization. Each permittivity tensor element for any magnetization direction and any sample surface orientation is simply determined by weighted summation of the principal spectra, where weights are given by crystallographic and magnetization orientations. The number of principal spectra depends on the symmetry of the crystal. In cubic crystals owning point symmetry we need only four principal spectra. Here, the principal spectra are expressed by ab initio calculations for bcc Fe, fcc Co and fcc Ni in optical range as well as in hard and soft x-ray energy range, i.e. at the 2p- and 3p-edges. We also express principal spectra analytically using modified Kubo formula.

Complex Pattern Formation from Current-Driven Dynamics of Single-Layer Epitaxial Islands on Crystalline Conducting Substrates

Science.gov (United States)

Kumar, Ashish; Dasgupta, Dwaipayan; Maroudas, Dimitrios

We report a systematic study of complex pattern formation resulting from the driven dynamics of single-layer homoepitaxial islands on face-centered cubic (FCC) crystalline conducting substrate surfaces under the action of an externally applied electric field. The analysis is based on an experimentally validated nonlinear model of mass transport via island edge atomic diffusion, which also accounts for edge diffusional anisotropy. We analyze the morphological stability and simulate the field-driven evolution of rounded islands for an electric field oriented along the fast diffusion direction. For larger than critical island sizes on {110} and {100} FCC substrates, we show that multiple necking instabilities generate complex island patterns, including void-containing islands, mediated by sequences of breakup and coalescence events and distributed symmetrically with respect to the electric field direction. We analyze the dependence of the formed patterns on the original island size and on the duration of application of the external field. Starting from a single large rounded island, we characterize the evolution of the number of daughter islands and their average size and uniformity. The analysis reveals that the pattern formation kinetics follows a universal scaling relation. Division of Materials Sciences & Engineering, Office of Basic Energy Sciences, U.S. Department of Energy (Award No.: DE-FG02-07ER46407).

Efficient LBM visual simulation on face-centered cubic lattices.

Science.gov (United States)

Petkov, Kaloian; Qiu, Feng; Fan, Zhe; Kaufman, Arie E; Mueller, Klaus

2009-01-01

The Lattice Boltzmann method (LBM) for visual simulation of fluid flow generally employs cubic Cartesian (CC) lattices such as the D3Q13 and D3Q19 lattices for the particle transport. However, the CC lattices lead to suboptimal representation of the simulation space. We introduce the face-centered cubic (FCC) lattice, fD3Q13, for LBM simulations. Compared to the CC lattices, the fD3Q13 lattice creates a more isotropic sampling of the simulation domain and its single lattice speed (i.e., link length) simplifies the computations and data storage. Furthermore, the fD3Q13 lattice can be decomposed into two independent interleaved lattices, one of which can be discarded, which doubles the simulation speed. The resulting LBM simulation can be efficiently mapped to the GPU, further increasing the computational performance. We show the numerical advantages of the FCC lattice on channeled flow in 2D and the flow-past-a-sphere benchmark in 3D. In both cases, the comparison is against the corresponding CC lattices using the analytical solutions for the systems as well as velocity field visualizations. We also demonstrate the performance advantages of the fD3Q13 lattice for interactive simulation and rendering of hot smoke in an urban environment using thermal LBM.

Orientation dependence of the dislocation microstructure in compressed body-centered cubic molybdenum

International Nuclear Information System (INIS)

Wang, S.; Wang, M.P.; Chen, C.; Xiao, Z.; Jia, Y.L.; Li, Z.; Wang, Z.X.

2014-01-01

The orientation dependence of the deformation microstructure has been investigated in commercial pure molybdenum. After deformation, the dislocation boundaries of compressed molybdenum can be classified, similar to that in face-centered cubic metals, into three types: dislocation cells (Type 2), and extended planar boundaries parallel to (Type 1) or not parallel to (Type 3) a (110) trace. However, it shows a reciprocal relationship between face-centered cubic metals and body-centered cubic metals on the orientation dependence of the deformation microstructure. The higher the strain, the finer the microstructure is and the smaller the inclination angle between extended planar boundaries and the compression axis is. - Highlights: • A reciprocal relationship between FCC metals and BCC metals is confirmed. • The dislocation boundaries can be classified into three types in compressed Mo. • The dislocation characteristic of different dislocation boundaries is different

Three-Dimensional Random Voronoi Tessellations: From Cubic Crystal Lattices to Poisson Point Processes

Science.gov (United States)

Lucarini, Valerio

2009-01-01

We perturb the simple cubic (SC), body-centered cubic (BCC), and face-centered cubic (FCC) structures with a spatial Gaussian noise whose adimensional strength is controlled by the parameter α and analyze the statistical properties of the cells of the resulting Voronoi tessellations using an ensemble approach. We concentrate on topological properties of the cells, such as the number of faces, and on metric properties of the cells, such as the area, volume and the isoperimetric quotient. The topological properties of the Voronoi tessellations of the SC and FCC crystals are unstable with respect to the introduction of noise, because the corresponding polyhedra are geometrically degenerate, whereas the tessellation of the BCC crystal is topologically stable even against noise of small but finite intensity. Whereas the average volume of the cells is the intensity parameter of the system and does not depend on the noise, the average area of the cells has a rather interesting behavior with respect to noise intensity. For weak noise, the mean area of the Voronoi tessellations corresponding to perturbed BCC and FCC perturbed increases quadratically with the noise intensity. In the case of perturbed SCC crystals, there is an optimal amount of noise that minimizes the mean area of the cells. Already for a moderate amount of noise ( α>0.5), the statistical properties of the three perturbed tessellations are indistinguishable, and for intense noise ( α>2), results converge to those of the Poisson-Voronoi tessellation. Notably, 2-parameter gamma distributions constitute an excellent model for the empirical pdf of all considered topological and metric properties. By analyzing jointly the statistical properties of the area and of the volume of the cells, we discover that also the cells shape, measured by the isoperimetric quotient, fluctuates. The Voronoi tessellations of the BCC and of the FCC structures result to be local maxima for the isoperimetric quotient among space

Atomic-scale microstructural characterization and dielectric properties of crystalline cubic pyrochlore Bi1.5MgNb1.5O7 nanoparticles synthesized by sol-gel method

KAUST Repository

Zhang, Yuan; Zhu, Xinhua; Zhou, Shunhua; Zhu, Jianmin; Liu, Zhiguo; Al-Kassab, Talaat

2013-01-01

Here, we report the atomic-scale microstructural characterization and dielectric properties of crystalline cubic pyrochlore Bi1.5MgNb 1.5O7 (BMN) nanoparticles with mean size of 70 nm, which were synthesized by sol-gel method. The crystallinity, phase formation, morphology, and surface microstructure of the BMN nanoparticles were characterized by X-ray diffraction (XRD), Raman spectra, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), respectively. The phase evolution of the BMN nanoparticles investigated by XRD patterns showed that uniform cubic pyrochlore BMN nanoparticles were obtained after calcination at temperature of 800 C, and their structural information was revealed by Raman spectrum. TEM images demonstrated that the BMN nanoparticles had a spherical morphology with an average particle size of 70 nm, and their crystalline nature was revealed by HRTEM images. In addition, HRTEM images also demonstrate a terrace-ledge-kink (TLK) surface structure at the edges of rough BMN nanoparticles, where the terrace was on the (100) plane, and the ledge on the (001) plane. The formation of such a TLK surface structure can be well explained by a theory of periodic bond chains. Due to the surface structural reconstruction in the BMN nanoparticles, the formation of a tetragonal structure in a rough BMN nanoparticle was also revealed by HRTEM image. The BMN nanoparticles exhibited dielectric constants of 50 at 100 kHz and 30 at 1 MHz, and the dielectric loss of 0.19 at 1 MHz. © 2013 Springer Science+Business Media Dordrecht.

Atomic-scale microstructural characterization and dielectric properties of crystalline cubic pyrochlore Bi1.5MgNb1.5O7 nanoparticles synthesized by sol-gel method

KAUST Repository

Zhang, Yuan

2013-12-24

Here, we report the atomic-scale microstructural characterization and dielectric properties of crystalline cubic pyrochlore Bi1.5MgNb 1.5O7 (BMN) nanoparticles with mean size of 70 nm, which were synthesized by sol-gel method. The crystallinity, phase formation, morphology, and surface microstructure of the BMN nanoparticles were characterized by X-ray diffraction (XRD), Raman spectra, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), respectively. The phase evolution of the BMN nanoparticles investigated by XRD patterns showed that uniform cubic pyrochlore BMN nanoparticles were obtained after calcination at temperature of 800 C, and their structural information was revealed by Raman spectrum. TEM images demonstrated that the BMN nanoparticles had a spherical morphology with an average particle size of 70 nm, and their crystalline nature was revealed by HRTEM images. In addition, HRTEM images also demonstrate a terrace-ledge-kink (TLK) surface structure at the edges of rough BMN nanoparticles, where the terrace was on the (100) plane, and the ledge on the (001) plane. The formation of such a TLK surface structure can be well explained by a theory of periodic bond chains. Due to the surface structural reconstruction in the BMN nanoparticles, the formation of a tetragonal structure in a rough BMN nanoparticle was also revealed by HRTEM image. The BMN nanoparticles exhibited dielectric constants of 50 at 100 kHz and 30 at 1 MHz, and the dielectric loss of 0.19 at 1 MHz. © 2013 Springer Science+Business Media Dordrecht.

Academic Training Lectures | FCC | 2-5 February

CERN Multimedia

2016-01-01

Please note that the next series of Academic Training Lectures will take place from 2 to 5 February 2016.   Tuesday, 2 February 2016 from 10.30 a.m. to 12.30 p.m. in the Filtration Plant (Building 222-R-001) FCC 1: Introduction to FCC by Michael Benedikt FCC 2: FCC Physics - Challenges and Potentials by Christophe Grojean, Michelangelo Mangano https://indico.cern.ch/event/472105/   Wednesday, 3 February 2016 from 10.30 a.m. to 12.30 p.m in the Filtration Plant (Building 222-R-001) FCC 3: FCC hh Detectors and Experiments by Werner Riegler FCC 4: Experimental Measurements and Detectors for the FCC-ee by Mogens Dam https://indico.cern.ch/event/472106/   Thursday, 4 February 2016 from 10.30 a.m. to 12.30 p.m in the Filtration Plant (Building 222-R-001) FCC 5: FCC Hadron Collider Design by Daniel Schulte FCC 6: FCC Lepton Collider Design by Frank Zimmermann https://indico...

Hexagonal close packed to face centered cubic polymorphic transformation in nanocrystalline titanium-zirconium system by mechanical alloying

International Nuclear Information System (INIS)

Bera, S.; Manna, I.

2006-01-01

The present study reports a reversible hexagonal close packed (hcp) to face centered cubic (fcc) polymorphic phase transformation in four different nanocrystalline titanium-zirconium binary alloys in the course of mechanical alloying in a planetary ball mill. This transformation is monitored at appropriate stages by X-ray diffraction and high-resolution transmission electron microscopy. Lattice parameter of the nanocrystalline fcc phase is a function of the alloy composition. For a given alloy, the lattice parameter and hence volume per atom increase with increase in milling time under comparable conditions. On the other hand, crystallite size, measured from X-ray peak broadening, significantly decreases with the progress of milling. It is suggested that structural instability due to plastic strain, increasing lattice expansion, and negative (from core to boundary) hydrostatic pressure is responsible for this hcp → fcc polymorphic transformation. The said transformation seems reversible as isothermal annealing at 1000 deg. C for 1 h or melting the powder mass leads to partial or complete transformation of the milled product from single phase fcc to hcp

Thermal-hydraulic study of fixed bed nuclear reactor (FBNR), in FCC, BCC and pseudo-random configurations of the core through CFD method

International Nuclear Information System (INIS)

Luna, M.; Chavez, I.; Cajas, D.; Santos, R.

2015-01-01

The study of thermal-hydraulic performance of a fixed bed nuclear reactor (FBNR) core and the effect of the porosity was studied by the CFD method with 'SolidWorks' software. The representative sections of three different packed beds arrangements were analyzed: face-centered cubic (FCC), body-centered cubic (BCC), and a pseudo-random, with values of porosity of 0.28, 0.33 and 0.53 respectively. The minimum coolant flow required to avoid the phase change for each one of the configurations was determined. The results show that the heat transfer rate increases when the porosity value decreases, and consequently the minimum coolant flow in each configuration. The results of minimum coolant flow were: 728.51 kg/s for the FCC structure, 372.72 kg/s for the BCC, and 304.96 kg/s for the pseudo-random. Meanwhile, the heat transfer coefficients in each packed bed were 6480 W/m 2 *K, 3718 W/m 2 *K and 3042 W/m 2 *K respectively. Finally the pressure drop was calculated, and the results were 0.588 MPa for FCC configuration, 0.033 MPa for BCC and 0.017 MPa for the pseudo-random one. This means that with a higher porosity, the fluid can circulate easier because there are fewer obstacles to cross, so there are fewer energy losses. (authors)

A kinematical model for the plastic deformation of face-centred cubic polycrystals

International Nuclear Information System (INIS)

Leffers, T.

1975-01-01

During the plastic deformation of a polycrystalline material the deformation of the individual grain must be adjusted to the deformation of the surrounding grains so that material continuity is maintained. This continuity condition is the essential feature distinguishing polycrystal deformation from single-crystal deformation. In the present work it is attempted to explain how the continuity condition is fulfilled in face-centred cubic polycrystals. The early treatments of the plastic deformation of polycrystalline materials were aimed directly at the formulation of a ''dynamical'' theory, i.e. it was the intention to cover the magnitude of the stresses involved as well as the slip processes producing the deformation. It is argued that rolling texture is a good tool for a necessary intermediate stage of establishing a ''kinematical'' model describing the slip processes, but not the magnitude of the necessary stresses. Three aspects of rolling texture are considered: (a) the development of the rolling textures found experimentally in face-centred cubic materials can be computer-simulated on the basis of models for the plastic deformation that only involve (111) slip; (b) experimentally that the widely accepted twinning theory for the transition in f.c.c. rolling texture does not reflect the behaviour of real materials; and (c) it is shown that the texture transition is thermally activated with an activation energy corresponding to that of cross slip. An electron-microscopical investigation of the slip process operating during rolling of f.c.c. polycrystals is also included. On the basis of the computer simulation of the texture formation supplemented by the experimental results a kinematical model is developed for the plastic deformation of f.c.c. polycrystals by rolling. In the proposed model the material continuity is maintained by inhomogeneous slip processes, combined with homogeneous multiple glide when the cross-slip frequency is high. (author)

Effect of the fcc-hcp martensitic transition on the equation of state of solid krypton up to 140 GPa

Science.gov (United States)

Rosa, A. D.; Garbarino, G.; Briggs, R.; Svitlyk, V.; Morard, G.; Bouhifd, M. A.; Jacobs, J.; Irifune, T.; Mathon, O.; Pascarelli, S.

2018-03-01

Solid krypton (Kr) undergoes a pressure-induced martensitic phase transition from a face-centered cubic (fcc) to a hexagonal close-packed (hcp) structure. These two phases coexist in a very wide pressure domain inducing important modifications of the bulk properties of the resulting mixed phase system. Here, we report a detailed in situ x-ray diffraction and absorption study of the influence of the fcc-hcp phase transition on the compression behavior of solid krypton in an extended pressure domain up to 140 GPa. The onset of the hcp-fcc transformation was observed in this study at around 2.7 GPa and the coexistence of these two phases up to 140 GPa, the maximum investigated pressure. The appearance of the hcp phase is also evidenced by the pressure-induced broadening and splitting of the first peak in the XANES spectra. We demonstrate that the transition is driven by a continuous nucleation and intergrowth of nanometric hcp stacking faults that evolve in the fcc phase. These hcp stacking faults are unaffected by high-temperature annealing, suggesting that plastic deformation is not at their origin. The apparent small Gibbs free-energy differences between the two structures that decrease upon compression may explain the nucleation of hcp stacking faults and the large coexistence domain of fcc and hcp krypton. We observe a clear anomaly in the equation of state of the fcc solid at ˜20 GPa when the proportion of the hcp form reaches ˜20 % . We demonstrate that this anomaly is related to the difference in stiffness between the fcc and hcp phases and propose two distinct equation of states for the low and high-pressure regimes.

EFFECT OF VANADIUM ON THE DEACTIVATION OF FCC CATALYSTS

Directory of Open Access Journals (Sweden)

Roncolatto R.E

1998-01-01

Full Text Available This work provides concrete evidence that vanadium causes the destruction of the zeolite in the FCC catalysts by a mechanism of acid attack or solid-solid transformation, as well as additional dealumination of the zeolite framework in the presence of steam and at high temperature. While these effects resulted in the reduction in crystallinity (zeolite Y content, specific area and unit cell size of the Y zeolite as the amount of vanadium in the catalysts increased, the reduction in activity was the most pronounced. The differences in these behaviors were interpreted and the model can be used for better catalyst formulation or screening.

Complex Pattern Formation from Current-Driven Dynamics of Single-Layer Homoepitaxial Islands on Crystalline Conducting Substrates

Science.gov (United States)

Kumar, Ashish; Dasgupta, Dwaipayan; Maroudas, Dimitrios

2017-07-01

We report a systematic study of complex pattern formation resulting from the driven dynamics of single-layer homoepitaxial islands on surfaces of face-centered-cubic (fcc) crystalline conducting substrates under the action of an externally applied electric field. The analysis is based on an experimentally validated nonlinear model of mass transport via island edge atomic diffusion, which also accounts for edge diffusional anisotropy. We analyze the morphological stability and simulate the field-driven evolution of rounded islands for an electric field oriented along the fast edge diffusion direction. For larger-than-critical island sizes on {110 } and {100 } fcc substrates, we show that multiple necking instabilities generate complex island patterns, including not-simply-connected void-containing islands mediated by sequences of breakup and coalescence events and distributed symmetrically with respect to the electric field direction. We analyze the dependence of the formed patterns on the original island size and on the duration of application of the external field. Starting from a single large rounded island, we characterize the evolution of the number of daughter islands and their average size and uniformity. The evolution of the average island size follows a universal power-law scaling relation, and the evolution of the total edge length of the islands in the complex pattern follows Kolmogorov-Johnson-Mehl-Avrami kinetics. Our study makes a strong case for the use of electric fields, as precisely controlled macroscopic forcing, toward surface patterning involving complex nanoscale features.

Nucleation of recrystallization at selected sites in deformed fcc metals

DEFF Research Database (Denmark)

Xu, Chaoling

The objective of this thesis is to explore nucleation of recrystallization at selected sites in selected face-centered-cubic (FCC) metals, namely cold rolled columnar-grained nickel and high purity aluminum further deformed by indenting. Various techniques, including, optical microscopy, electron...... backscattered diffraction (EBSD), electron channeling contrast (ECC) and synchrotron X-ray technique, differential-aperture X-ray microscopy (DAXM), were used to characterize the microstructures, to explore nucleation sites, orientation relationships between nuclei and deformed microstructures, and nucleation...... mechanisms. In the cold rolled nickel samples, the preference of triple junctions (TJs) and grain boundaries (GBs) as nucleation sites is observed. The majorities of the nuclei have the same orientations as the surrounding matrix or are twin-related to a surrounding deformed grain. Only a few nuclei...

NMR-ON on 60CoCo(fcc, hcp, thin film), 52MnCo(fcc), and 90NbCo(fcc)

International Nuclear Information System (INIS)

Zech, E.; Hagn, E.; Ernst, H.; Eska, G.

1978-01-01

With the NMR-ON method the magnetic hyperfine splitting constant of dilute impurities in a ferromagnetic host material (Fe, Ni, Co) can be determined with high accuracy (10 -3 ...10 -4 ). Only few NMR-ON experiments with Co as host lattice have been performed up to now. In constrast to Fe and Ni, two stable modifications exist for Co (fcc and hcp). In the hcp case the magnetic hyperfine field is expected to be anisotropic. Due to the electric field gradient, which is present in this case, a (small) guadrupole interaction is superimposed to the magnetic hyperfine interaction. For 60 CoCo measurements were done on a fcc foil, a hcp single crystal, and on thin films, which were prepared by evaporating Co into glass. For 52 MnCo and 90 NbCo measurements were performed for fcc Co. (Auth.)

Lattice Dynamics of fcc Ca

DEFF Research Database (Denmark)

Stassis, C.; Zaretsky, J.; Misemer, D. K.;

1983-01-01

A large single crystal of FCC Ca was grown and was used to study the lattice dynamics of this divalent metal by coherent inelastic neutron scattering. The phonon dispersion curves were measured, at room temperature, along the [ξ00], [ξξ0], [ξξξ], and [0ξ1] symmetry directions. The dispersion curves...... to the propagation of elastic waves. The frequencies of the T1[ξξ0] branch for ξ between approximately 0.5 and 0.8 are slightly above the velocity-of-sound line determined from the low-frequency measurements. Since a similar effect has been observed in FCC Yb, it is natural to assume that the anomalous dispersion...... bear a striking resemblance to those of FCC Yb, which is also a divalent metal with an electronic band structure similar to that of Ca. In particular, the shear moduli c44 and (c11-c 12)/2 differ by a factor of 3.4, which implies that FCC Ca (like FCC Yb) is very anisotropic with regard...

Ferromagnetism and Crystalline Electric Field Effects in Cubic UX2Zn20 (X=Co, Rh, Ir)

Science.gov (United States)

Bauer, E. D.; Ronning, F.; Silhanek, A.; Harrison, N.; Thompson, J. D.; Sarrao, J. L.; Movshovich, R.; Hundley, M. F.; Jaime, M.; Daniel, E.; Booth, C. H.

2006-03-01

The properties of a new class of cubic UX2Zn20 (X=Co, Rh, Ir) heavy fermion compounds have been investigated by means of magnetic susceptibility, specific heat, electrical resistivity, and x-ray absorption spectroscopy. Both UCo2Zn20 and URh2Zn20 show peaks in C(T) and χ(T) at ˜5-10 K suggesting the presence of crystalline electric field (CEF) effects in these materials, i.e., a localized 5f^2 configuration of uranium. In addition, measurements in high magnetic fields up to 40 T are consistent with a CEF model of a nonmagnetic ground state and a magnetic first excited state separated by ˜ 20 K. In contrast, UIr2Zn20 exhibits a first-order ferromagnetic transition at Tc=2.75 K with a saturation moment μsat=0.5 μB in the ferromagnetic state. All compounds in this series are heavy fermion materials with enhanced electronic specific heat coefficients γ˜ 150-300 mJ/molK^2. The physical properties of UX2Zn20 (X=Co, Rh, Ir) will be discussed.

Shear response of Σ3{112} twin boundaries in face-centered-cubic metals

Science.gov (United States)

Wang, J.; Misra, A.; Hirth, J. P.

2011-02-01

Molecular statics and dynamics simulations were used to study the mechanisms of sliding and migration of Σ3{112} incoherent twin boundaries (ITBs) under applied shear acting in the boundary in the face-centered-cubic (fcc) metals, Ag, Cu, Pd, and Al, of varying stacking fault energies. These studies revealed that (i) ITBs can dissociate into two phase boundaries (PBs), bounding the hexagonal 9R phase, that contain different arrays of partial dislocations; (ii) the separation distance between the two PBs scales inversely with increasing stacking fault energy; (iii) for fcc metals with low stacking fault energy, one of the two PBs migrates through the collective glide of partials, referred to as the phase-boundary-migration (PBM) mechanism; (iv) for metals with high stacking energy, ITBs experience a coupled motion (migration and sliding) through the glide of interface disconnections, referred to as the interface-disconnection-glide (IDG) mechanism.

Ab Initio Guided Low Temperature Synthesis Strategy for Smooth Face–Centred Cubic FeMn Thin Films

Directory of Open Access Journals (Sweden)

Friederike Herrig

2018-05-01

Full Text Available The sputter deposition of FeMn thin films with thicknesses in the range of hundred nanometres and beyond requires relatively high growth temperatures for the formation of the face-centred cubic (fcc phase, which results in high thin film roughness. A low temperature synthesis strategy, based on local epitaxial growth of a 100 nm thick fcc FeMn film as well as a Cu nucleation layer on an α-Al2O3 substrate at 160 °C, enables roughness values (Ra as low as ~0.6 nm, which is in the same order of magnitude as the pristine substrate (~0.1 nm. The synthesis strategy is guided by ab initio calculations, indicating very strong interfacial bonding of the Cu nucleation layer to an α-Al2O3 substrate (work of separation 5.48 J/m²—which can be understood based on the high Cu coordination at the interface—and between fcc FeMn and Cu (3.45 J/m². Accompanied by small lattice misfits between these structures, the strong interfacial bonding is proposed to enable the local epitaxial growth of a smooth fcc FeMn thin film. Based on the here introduced synthesis strategy, the implementation of fcc FeMn based thin film model systems for materials with interface dominated properties such as FeMn steels containing κ-carbide precipitates or secondary phases appears meaningful.

9th FCC-ee (TLEP) Physics Workshop

CERN Document Server

2015-01-01

This is the 9th in the series of FCCee/TLEP-related workshops. It follows on from the sucessful 8th TLEP workshop that took place in Paris on 27-29 October 2014, and the FCC kick-off meeting held on 12-15 February 2014 at University of Geneva. The workshop is open to all FCC-ee /TLEP design study members, and more generally to all interested in a precision Z, W, H, top factory. The focus will be on physics and experiments at the FCC-ee, but a more general session is organized the first day (Tuesday 3 February afternoon) with presentations about the FCC design study as a whole, and on machine and physics for the FCC-ee and the FCC-hh, with synergies and complementarities. This session is aimed at a larger audience, towards improving the project visibility in Italy. It will be followed by a social dinner in the evening. The workshop starts on Tuesday at 13:30 and ends on Thursday 16:00. Registration is now open, please proceed at your earliest convenience! Please visit the FCC-ee / TLEP web site, and subscrib...

Deformed lattice states in a Zn{sub 0.9}V{sub 0.1}Se cubic crystal

Energy Technology Data Exchange (ETDEWEB)

Maksimov, V. I., E-mail: kokailo@rambler.ru; Dubinin, S. F.; Surkova, T. P.; Parkhomenko, V. D. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation)

2016-01-15

Neutron scattering patterns have been recorded for a bulk Zn{sub 0.9}V{sub 0.1}Se cubic crystal at room temperature; they are indicative of macroscopic deformation in the material and its significant inhomogeneity. Specific features of the previously found state, preceding the fcc ↔ hcp structural transformation of the sphalerite lattice upon strong destabilization induced by vanadium ions in the doped ZnSe matrix, are discussed taking into account the data obtained.

The FCC-ee study: Progress and challenges

OpenAIRE

Koratzinos, Michael; Aumon, Sandra; Bogomyagkov, Anton; Boscolo, Manuela; Cook, Charlie; Doblhammer, Andreas; Härer, Bastian; Tomás, Rogelio; Levichev, Evgeny; Medina Medrano, Luis; Shatilov, Dmitry; Wienands, Ulrich; Zimmermann, Frank

2015-01-01

The FCC (Future Circular Collider) study represents a vision for the next large project in high energy physics, comprising an 80-100 km tunnel that can house a future 100 TeV hadron collider. The study also includes a high luminosity e+e- collider operating in the centre-of-mass energy range of 90-350 GeV as a possible intermediate step, the FCC-ee. The FCC-ee aims at definitive electro-weak precision measurements of the Z, W, H and top particles, and search for rare phenomena. Although FCC-e...

FCC Official Brochure - Japanese Version

CERN Multimedia

AUTHOR|(CDS)2082248; Yamamoto, Akira; Uchibori, Yumemi.katsuki

2017-01-01

The FCC brochure describes the main scope of the study and give more information about the main scenarios explored under the study. It also highlights the ongoing R&D efforts launched by the FCC study. Finally, it offers more information about the collaboration and a list of useful contact details.

FCC Official Brochure - French Version

CERN Multimedia

Charitos, Panagiotis

2017-01-01

The FCC brochure describes the main scope of the study and give more information about the main scenarios explored under the study. It also highlights the ongoing R&D efforts launched by the FCC study. Finally, it offers more information about the collaboration and a list of useful contact details.

FCC Official Brochure - German version

CERN Multimedia

Charitos, Panagiotis

2017-01-01

The FCC brochure describes the main scope of the study and give more information about the main scenarios explored under the study. It also highlights the ongoing R&D efforts launched by the FCC study. Finally, it offers more information about the collaboration and a list of useful contact details.

Frustrated Heisenberg Antiferromagnets on Cubic Lattices: Magnetic Structures, Exchange Gaps, and Non-Conventional Critical Behaviour

OpenAIRE

Ignatenko, A. N.; Irkhin, V. Yu.

2016-01-01

We have studied the Heisenberg antiferromagnets characterized by the magnetic structures with the periods being two times larger than the lattice period. We have considered all the types of the Bravais lattices (simple cubic, bcc and fcc) and divided all these antiferromagnets into 7 classes i.e. 3 plus 4 classes denoted with symbols A and B correspondingly. The order parameter characterizing the degeneracies of the magnetic structures is an ordinary Neel vector for A classes and so-called 4-...

Face-centered-cubic lithium crystals formed in mesopores of carbon nanofiber electrodes.

Science.gov (United States)

Lee, Byoung-Sun; Seo, Jong-Hyun; Son, Seoung-Bum; Kim, Seul Cham; Choi, In-Suk; Ahn, Jae-Pyoung; Oh, Kyu Hwan; Lee, Se-Hee; Yu, Woong-Ryeol

2013-07-23

In the foreseeable future, there will be a sharp increase in the demand for flexible Li-ion batteries. One of the most important components of such batteries will be a freestanding electrode, because the traditional electrodes are easily damaged by repeated deformations. The mechanical sustainability of carbon-based freestanding electrodes subjected to repeated electrochemical reactions with Li ions is investigated via nanotensile tests of individual hollow carbon nanofibers (HCNFs). Surprisingly, the mechanical properties of such electrodes are improved by repeated electrochemical reactions with Li ions, which is contrary to the conventional wisdom that the mechanical sustainability of carbon-based electrodes should be degraded by repeated electrochemical reactions. Microscopic studies reveal a reinforcing mechanism behind this improvement, namely, that inserted Li ions form irreversible face-centered-cubic (FCC) crystals within HCNF cavities, which can reinforce the carbonaceous matrix as strong second-phase particles. These FCC Li crystals formed within the carbon matrix create tremendous potential for HCNFs as freestanding electrodes for flexible batteries, but they also contribute to the irreversible (and thus low) capacity of HCNFs.

BDA: A novel method for identifying defects in body-centered cubic crystals.

Science.gov (United States)

Möller, Johannes J; Bitzek, Erik

2016-01-01

The accurate and fast identification of crystallographic defects plays a key role for the analysis of atomistic simulation output data. For face-centered cubic (fcc) metals, most existing structure analysis tools allow for the direct distinction of common defects, such as stacking faults or certain low-index surfaces. For body-centered cubic (bcc) metals, on the other hand, a robust way to identify such defects is currently not easily available. We therefore introduce a new method for analyzing atomistic configurations of bcc metals, the BCC Defect Analysis (BDA). It uses existing structure analysis algorithms and combines their results to uniquely distinguish between typical defects in bcc metals. In essence, the BDA method offers the following features:•Identification of typical defect structures in bcc metals.•Reduction of erroneously identified defects by iterative comparison to the defects in the atom's neighborhood.•Availability as ready-to-use Python script for the widespread visualization tool OVITO [http://ovito.org].

Large-area photonic crystals

Science.gov (United States)

Ruhl, Tilmann; Spahn, Peter; Hellmann, Gotz P.; Winkler, Holger

2004-09-01

Materials with a periodically modulated refractive index, with periods on the scale of light wavelengths, are currently attracting much attention because of their unique optical properties which are caused by Bragg scattering of the visible light. In nature, 3d structures of this kind are found in the form of opals in which monodisperse silica spheres with submicron diameters form a face-centered-cubic (fcc) lattice. Artificial opals, with the same colloidal-crystalline fcc structure, have meanwhile been prepared by crystallizing spherical colloidal particles via sedimentation or drying of dispersions. In this report, colloidal crystalline films are introduced that were produced by a novel technique based on shear flow in the melts of specially designed submicroscopic silica-polymer core-shell hybrid spheres: when the melt of these spheres flows between the plates of a press, the spheres crystallize along the plates, layer by layer, and the silica cores assume the hexagonal order corresponding to the (111) plane of the fcc lattice. This process is fast and yields large-area films, thin or thick. To enhance the refractive index contrast in these films, the colloidal crystalline structure was inverted by etching out the silica cores with hydrofluoric acid. This type of an inverse opal, in which the fcc lattice is formed by mesopores, is referred to as a polymer-air photonic crystal.

Depth of origin of atoms sputtered from crystalline targets

International Nuclear Information System (INIS)

Shapiro, M.H.; Trovato, E.; Tombrello, T.A.

2001-01-01

Recently, V.I. Shulga and W. Eckstein (Nucl. Instr. and Meth. B 145 (1998) 492) investigated the depth of origin of atoms sputtered from random elemental targets using the Monte Carlo code TRIM.SP and the lattice code OKSANA. They found that the mean depth of origin is proportional to N -0.86 , where N is the atomic density; and that the most probable escape depth is ∼λ 0 /2, where λ 0 is the mean atomic distance. Since earlier molecular dynamics simulations with small crystalline elemental targets typically produced a most probable escape depth of zero (i.e., most sputtered atoms came from the topmost layer of the target), we have carried out new molecular dynamics simulations of sputtered atom escape depths with much larger crystalline targets. Our new results, which include the bcc targets Cs, Rb and W, as well as the fcc targets Cu and Au predict that the majority of sputtered atoms come from the first atomic layer for the bcc(1 0 0), bcc(1 1 1), fcc(1 0 0) and fcc(1 1 1) targets studied. For the high-atomic density targets Cu, Au and W, the mean depth of origin of sputtered atoms typically is less than 0.25λ 0 . For the low-atomic density targets Cs and Rb, the mean depth of origin of sputtered atoms is considerably larger, and depends strongly on the crystal orientation. We show that the discrepancy between the single-crystal and amorphous target depth of origin values can be resolved by applying a simple correction to the single-crystal results

Martensitic transformation, fcc and hcp relative phase stability, and thermal cycling effects in Fe-Mn and Fe-Mn-X Alloys (X = Si, Co)

International Nuclear Information System (INIS)

Baruj, Alberto

1999-01-01

In this Thesis we present a study of the fcc and hcp relative phase stability in the Fe-Mn and Fe-Mn-Co systems. In particular, we have investigated the effect of two main factors affecting the relative phase stability: changes in the chemical composition of the alloys and changes in the density of crystalline defects in the microstructure.In order to analyse the effect of chemical composition, we have performed an experimental study of the fcc/hcp martensitic transformation temperatures in Fe-Mn-Co alloys in the composition range lying between 15% and 34% Mn, and between 1% and 16% Co.We have measured the martensitic transformation temperatures by means of dilatometry and electrical resistivity.We have combined this information with measurements of the fcc/hcp martensitic transformation temperatures in Co-rich alloys to perform a modelling of the Gibbs energy function for the hcp phase in the Fe-Mn-Co and Fe-Co systems.We found that, for alloys in the Mn range between 17% and 25%, Co additions tend to stabilise slightly the fcc phase.In the alloys with Mn contents below that range, increasing the amount of Co stabilise the bcc phase. In alloys with Mn contents above 25% the Neel temperature is depressed by the addition of Co, which stabilise the hcp phase.In order to investigate the effect of changes in the density of crystalline defects, we have performed thermal cycling experiments through the fcc/hcp martensitic transformation in Fe-Mn, Fe-Mn-Co and Fe-Mn-Si alloys.We have applied the thermodynamic description obtained before in order to analyse these experiments.We found in the thermal cycling experiments a first stage where the martensitic transformation is promoted.This stage occurs in all the studied alloys during the first cycle or the two first cycles.Increasing the number of thermal cycles, the promotion stage is replaced by an inhibition of the transformation stage.We propose a possible microstructural interpretation of these phenomena where the plastic

FCC-ee Physics workshop | 19-21 June 2014

CERN Multimedia

2014-01-01

The 7th FCC-ee/TLEP workshop, the first after the FCC kick-off in February 2014, will be focused on physics and experiments.     It will take place on 19-21 June at CERN in the TH auditorium. The registration is open and the agenda is available on the indico web page: http://indico.cern.ch/event/313708/. You are all cordially invited to attend! This will be the first in a series of workshops that will lead us to the first FCC-ee physics milestone, a document defining the physics landscape and study plans, required for March 2015. More information can be found here. FCC-ee is a high-luminosity Z, W, Higgs and top factory, to be hosted in a 100km tunnel, possibly as the first step towards a 100 TeV pp collider FCC-hh. These two machines are being studied within the FCC design study. High precision, high statistics and a clean environment are the tools available in FCC-ee to shed light on the unknown physics that underlies present mysteries: dark matter, the baryon asymmetry of th...

Bonding properties of FCC-like Au ₄₄ (SR) ₂₈ clusters from X-ray absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yang, Rui [Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.; Chevrier, Daniel M. [Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.; Zeng, Chenjie [Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.; Jin, Rongchao [Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.; Zhang, Peng [Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.

2017-11-01

Thiolate-protected gold clusters with precisely controlled atomic composition have recently emerged as promising candidates for a variety of applications because of their unique optical, electronic, and catalytic properties. The recent discovery of the Au44(SR)28 total structure is considered as an interesting finding in terms of the face-centered cubic (FCC)-like core structure in small gold-thiolate clusters. Herein, the unique bonding properties of Au44(SR)28 is analyzed using temperature-dependent X-ray absorption spectroscopy (XAS) measurements at the Au L3-edge and compared with other FCC-like clusters such as Au36(SR)24 and Au28(SR)20. A negative thermal expansion was detected for the Au–Au bonds of the metal core (the first Au–Au shell) and was interpreted based on the unique Au core structure consisting of the Au4 units. EXAFS fitting results from Au28(SR)20, Au36(SR)24, and Au44(SR)28 show a size-dependent negative thermal expansion behavior in the first Au–Au shell, further highlighting the importance of the Au4 units in determining the Au core bonding properties and shedding light on the growth mechanism of these FCC-like Au clusters.

Investigating effects of BCC and FCC arrangements on flow and heat transfer characteristics in pebbles through CFD methodology

Energy Technology Data Exchange (ETDEWEB)

Ferng, Yuh Ming, E-mail: ymferng@ess.nthu.edu.tw [Department of Engineering and System Science, Institute of Nuclear Engineering and Science, National Tsing Hua University, 101, Sec. 2. Kuang-Fu Rd., Hsingchu 30013, Taiwan, ROC (China); Lin, Kun-Yueh [Department of Engineering and System Science, Institute of Nuclear Engineering and Science, National Tsing Hua University, 101, Sec. 2. Kuang-Fu Rd., Hsingchu 30013, Taiwan, ROC (China)

2013-05-15

Highlights: ► An HTGR would be one of the possible energy generation sources. ► We propose a CFD model to study effects of pebble arrangements for a PRB core. ► The entrance effect on the Nu number can be reasonably captured. ► The present predicted Nu versus Re{sub p} shows good agreement with data and correlation. ► Using FCC lattice in a core, simulation results may be non-conservative. -- Abstract: A high temperature gas cooled reactor (HTGR) would be one of the possible energy generation sources due to its advantages of inherently safety performance and higher conversion efficiency, etc. However, safety is the most important issue for its commercialization in energy industry. It is very crucial for safety design and operation of an HTGR to investigate its thermal–hydraulic characteristics. In this article, a computational fluid dynamics (CFD) methodology is proposed to investigate effects of different arrangements on these characteristics for an HTGR with a pebble bed (PB) core. Two kinds of arrangement: body-centered cubic (BCC) and face-centered cubic (FCC) are studies herein. Based on the simulation results, higher heat transfer capability and lower pebble temperature are predicted in the pebbles with the FCC-arrangement. The thermally fully-developed flow condition may be reached, which is shown in the result that the predicted average Nussel (Nu) number decreases from the 1st layer and reaches to an asymptotic value as the gas passes through the 6th layer of pebbles. This entrance effect reveals that the system codes using the correlations developed from the fully-developed flow condition can be appropriately applied in the entire PBR core. In addition, the present predicted dependence of Nu number on the inlet Reynolds (Re) number shows good agreement with that obtained from the well-known KTA. Measured data of Nu number versus Re number are also used to validate the CFD model.

FCC 3 and FCC 4 (2/4)

CERN Multimedia

CERN. Geneva; Dam, Mogens

2016-01-01

Abstract: Owing to its specific interaction region design, the FCC-ee will be able to deliver unprecedented luminosities at centre-of-mass energies ranging from below the Z pole to the ttbar threshold and above. Operation at four energy regimes - at the Z pole, at the WW threshold, at 240 GeV for Higgs production, and at the ttbar thre...

On the electron density localization in elemental cubic ceramic and FCC transition metals by means of a localized electrons detector.

Science.gov (United States)

Aray, Yosslen; Paredes, Ricardo; Álvarez, Luis Javier; Martiz, Alejandro

2017-06-14

The electron density localization in insulator and semiconductor elemental cubic materials with diamond structure, carbon, silicon, germanium, and tin, and good metallic conductors with face centered cubic structure such as α-Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au, was studied using a localized electrons detector defined in the local moment representation. Our results clearly show an opposite pattern of the electron density localization for the cubic ceramic and transition metal materials. It was found that, for the elemental ceramic materials, the zone of low electron localization is very small and is mainly localized on the atomic basin edges. On the contrary, for the transition metals, there are low-valued localized electrons detector isocontours defining a zone of highly delocalized electrons that extends throughout the material. We have found that the best conductors are those in which the electron density at this low-value zone is the lowest.

PURIFIED WASTE FCC CATALYST AS A CEMENT REPLACEMENT MATERIAL

Directory of Open Access Journals (Sweden)

Danute Vaiciukyniene

2015-06-01

Full Text Available Zeolites are commonly used in the fluid catalytic cracking process. Zeolite polluted with oil products and became waste after some time used. The quantity of this waste inevitably rises by expanding rapidly oil industry. The composition of these catalysts depends on the manufacturer and on the process that is going to be used. The main factors retarding hydration process of cement systems and modifying them strength are organic compounds impurities in the waste FCC catalyst. The present paper shows the results of using purified waste FCC catalyst (pFCC from Lithuania oil refinery, as Portland cement replacement material. For this purpose, the purification of waste FCC catalyst (FCC samples was treated with hydrogen peroxide. Hydrogen peroxide (H2O2 is one of the most powerful oxidizers known. By acting of waste with H2O2 it can eliminate the aforementioned waste deficiency, and the obtained product becomes one of the most promising ingredients, in new advanced building materials. Hardened cement paste samples with FCC or pFCC were formed. It was observed that the pFCC blended cements developed higher strength, after 28 days, compared to the samples with FCC or reference samples. Typical content of Portland cement substituting does not exceed 30 % of mass of Portland cement in samples. Reducing the consumption of Portland cement with utilizing waste materials is preferred for reasons of environmental protection.

CoPt nanoparticles by chemical reduction

International Nuclear Information System (INIS)

Wang, H.L.; Zhang, Y.; Huang, Y.; Zeng, Q.; Hadjipanayis, G.C.

2004-01-01

CoPt nanoparticles with a size of 1-2 nm were synthesized by chemical reduction using the solvents of water and alcohol. A phase transformation from the originally disordered face centered cubic (FCC) structure to an ordered face centered tetragonal L1 0 structure occurred after annealing, which results in the coercivity up to 9 kOe because of the high anisotropy of the tetragonal phase (K∼2-4x10 7 erg/cm 3 ) (Philos. Mag. 13 (1966) 567; IEEE Trans. Magn. 20 (1984) 1625). HREM images of as-grow Co 48 Pt 52 shows the single-crystalline FCC structure with the shape of columnar and spherical

FCC-ee: Energy Calibration

Energy Technology Data Exchange (ETDEWEB)

Koratzinos, M. [Univ. of Geneva (Switzerland); Blondel, A. [Univ. of Geneva (Switzerland); Gianfelice-Wendt, E. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Zimmermann, F. [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

2015-06-02

The FCC-ee aims to improve on electroweak precision measurements, with goals of 100 ke V on the Z mass and width, and a fraction of MeV on the W mass. Compared to LEP, this implies a much improved knowledge of the center-of-mass energy when operating at the Z peak and WW threshold. This can be achieved by making systematic use of resonant depolarization. A number of issues have been identified, due in particular to the long polarization times. However the smaller emittance and energy spread of FCC-ee with respect to LEP should help achieve a much improved performance.

FCC-ee: Energy calibration

CERN Document Server

Koratzinos, M.; Gianfelice-Wendt, E.; Zimmermann, F.

The FCC-ee aims to improve on electroweak precision measurements, with goals of 100 keV on the Z mass and width, and a fraction of MeV on the W mass. Compared to LEP, this implies a much improved knowledge of the centre-of-mass energy when operating at the Z peak and WW threshold. This can be achieved by making systematic use of resonant depolarization. A number of issues have been identified, due in particular to the long polarization times. However the smaller emittance and energy spread of FCC-ee with respect to LEP should help achieve a much improved performance.

Dislocation creation and void nucleation in FCC ductile metals under tensile loading: a general microscopic picture.

Science.gov (United States)

Pang, Wei-Wei; Zhang, Ping; Zhang, Guang-Cai; Xu, Ai-Guo; Zhao, Xian-Geng

2014-11-10

Numerous theoretical and experimental efforts have been paid to describe and understand the dislocation and void nucleation processes that are fundamental for dynamic fracture modeling of strained metals. To date an essential physical picture on the self-organized atomic collective motions during dislocation creation, as well as the essential mechanisms for the void nucleation obscured by the extreme diversity in structural configurations around the void nucleation core, is still severely lacking in literature. Here, we depict the origin of dislocation creation and void nucleation during uniaxial high strain rate tensile processes in face-centered-cubic (FCC) ductile metals. We find that the dislocations are created through three distinguished stages: (i) Flattened octahedral structures (FOSs) are randomly activated by thermal fluctuations; (ii) The double-layer defect clusters are formed by self-organized stacking of FOSs on the close-packed plane; (iii) The stacking faults are formed and the Shockley partial dislocations are created from the double-layer defect clusters. Whereas, the void nucleation is shown to follow a two-stage description. We demonstrate that our findings on the origin of dislocation creation and void nucleation are universal for a variety of FCC ductile metals with low stacking fault energies.

Outline and Status of the FCC-ee Design Study

CERN Document Server

Zimmermann, Frank

2015-01-01

The Update of the European Strategy for Particle Physics in 2013 [1] declared as its second highest priority that “…to propose an ambitious post-LHC accelerator project….., CERN should undertake design studies for accelerator projects in a global context,…with emphasis on proton-proton and electron-positron high-energy frontier machines…”. In response to this request, the global Future Circular Collider (FCC) study is designing a 100-TeV proton collider (FCC-hh) in a new ~100 km tunnel near Geneva, a high-luminosity electron-positron collider (FCC-ee) as a potential intermediate step, and a lepton-hadron option (FCC-he). The FCC study comprises accelerators, technology, infrastructure, detector, physics, concepts for worldwide data services, international governance models, and implementation scenarios. The FCC study is mandated to deliver a Conceptual Design Report and preliminary cost estimate by the time of the next European Strategy Update expected for 2019. As of July 2015, 58 institutes from...

Study of Collective Effects in the FCC-ee Collider

OpenAIRE

Zobov, Mikhail; Belli, Eleonora; Castorina, Giovanni; Migliorati, Mauro; Persichelli, Serena; Rumolo, Giovanni; Spataro, Bruno

2018-01-01

The Future Circular Collider (FCC) study aims at designing different options of a post-LHC collider. The high luminosity electron-positron collider FCC-ee based on the crab waist concept is considered as an intermediate step on the way towards FCC-hh, a 100 TeV hadron collider using the same tunnel of about 100 km. Due to a high intensity of circulating beams the impact of collective effects on FCC-ee performance has to be carefully analyzed. In this paper we evaluate beam coupling impedance ...

Vacancy behavior in a compressed fcc Lennard-Jones crystal

International Nuclear Information System (INIS)

Beeler, J.R. Jr.

1981-12-01

This computer experiment study concerns the determination of the stable vacancy configuration in a compressed fcc Lennard-Jones crystal and the migration of this defect in a compressed crystal. Isotropic and uniaxial compression stress conditions were studied. The isotropic and uniaxial compression magnitudes employed were 0.94 less than or equal to eta less than or equal to 1.5, and 1.0 less than or equal to eta less than or equal to 1.5, respectively. The site-centered vacancy (SCV) was the stable vacancy configuration whenever cubic symmetry was present. This includes all of the isotropic compression cases and the particular uniaxial compression case (eta = √2) that give a bcc structure. In addition, the SCV was the stable configuration for uniaxial compression eta 1.20, the SV-OP is an extended defect and, therefore, a saddle point for SV-OP migration could not be determined. The mechanism for the transformation from the SCV to the SV-OP as the stable form at eta = 1.29 appears to be an alternating sign [101] and/or [011] shear process

HOM power in FCC-ee cavities

CERN Document Server

Karpov, Ivan; Chapochnikova, Elena

2018-01-01

This Note summarizes the results of the power loss calculations for FCC-ee machines with 400.79 MHz cavity options. The requirements for the single-cell cavity design and for the operation with beam are obtained from the results for the high-current FCC-ee machine (Z). For other machines the power loss is sufficiently low and can be absorbed and extracted by foreseen HOM couplers.

The FCC-ee study: Progress and challenges

CERN Document Server

Koratzinos, Michael; Bogomyagkov, Anton; Boscolo, Manuela; Cook, Charlie; Doblhammer, Andreas; Härer, Bastian; Tomás, Rogelio; Levichev, Evgeny; Medina Medrano, Luis; Shatilov, Dmitry; Wienands, Ulrich; Zimmermann, Frank

The FCC (Future Circular Collider) study represents a vision for the next large project in high energy physics, comprising an 80-100 km tunnel that can house a future 100 TeV hadron collider. The study also includes a high luminosity e+e- collider operating in the centre-of-mass energy range of 90-350 GeV as a possible intermediate step, the FCC-ee. The FCC-ee aims at definitive electro-weak precision measurements of the Z, W, H and top particles, and search for rare phenomena. Although FCC-ee is based on known technology, the goal performance in luminosity and energy calibration make it quite challenging. During 2014 the study went through an exploration phase. The study has now entered its second year and the aim is to produce a conceptual design report during the next three to four years. We here report on progress since the last IPAC conference.

Transformation from amorphous to nano-crystalline SiC thin films ...

Indian Academy of Sciences (India)

Administrator

phous SiC to cubic nano-crystalline SiC films with the increase in the gas flow ratio. Raman scattering ... Auger electron spectroscopy showed that the carbon incorporation in the .... with a 514 nm Ar+ laser excitation source and the laser.

Luminosity Targets for FCC-hh

CERN Document Server

Zimmermann, F.; Buffat, X.; Schulte, D.

2016-01-01

We discuss the choice of target values for the peak and integrated luminosity of a future high-energy frontier circular hadron collider (FCC-hh). We review the arguments on the physics reach of a hadron collider. Next we show that accelerator constraints will limit the beam current and the turnaround time. Taking these limits into account, we derive an expression for the ultimate integrated luminosity per year, depending on a possible pile-up limit imposed by the physics experiments. We finally benchmark our result against the planned two phases of FCC-hh [1, 2, 3

Uhlenbeck-Ford model: Phase diagram and corresponding-states analysis

Science.gov (United States)

Paula Leite, Rodolfo; Santos-Flórez, Pedro Antonio; de Koning, Maurice

2017-09-01

Using molecular dynamics simulations and nonequilibrium thermodynamic-integration techniques we compute the Helmholtz free energies of the body-centered-cubic (bcc), face-centered-cubic (fcc), hexagonal close-packed, and fluid phases of the Uhlenbeck-Ford model (UFM) and use the results to construct its phase diagram. The pair interaction associated with the UFM is characterized by an ultrasoft, purely repulsive pair potential that diverges logarithmically at the origin. We find that the bcc and fcc are the only thermodynamically stable crystalline phases in the phase diagram. Furthermore, we report the existence of two reentrant transition sequences as a function of the number density, one featuring a fluid-bcc-fluid succession and another displaying a bcc-fcc-bcc sequence near the triple point. We find strong resemblances to the phase behavior of other soft, purely repulsive systems such as the Gaussian-core model (GCM), inverse-power-law, and Yukawa potentials. In particular, we find that the fcc-bcc-fluid triple point and the phase boundaries in its vicinity are in good agreement with the prediction supplied by a recently proposed corresponding-states principle [J. Chem. Phys. 134, 241101 (2011), 10.1063/1.3605659; Europhys. Lett. 100, 66004 (2012), 10.1209/0295-5075/100/66004]. The particularly strong resemblance between the behavior of the UFM and GCM models are also discussed.

Hydrothermal synthesis and white light emission of cubic ZrO2:Eu3+ nanocrystals

International Nuclear Information System (INIS)

Meetei, Sanoujam Dhiren; Singh, Shougaijam Dorendrajit

2014-01-01

Highlights: • White light emitting cubic ZrO 2 :Eu 3+ nanocrystal is synthesized by hydrothermal technique. • Eu 3+ is used to stabilize crystalline phase and to get red counterpart of the white light. • Defect emission and Eu 3+ emission combined to give white light. • The white light emitted from this nanocrystal resembles vertical daylight of the Sun. • Lifetime corresponding to red counterpart of the sample is far longer than conventional white light emitters. -- Abstract: Production of white light has been a promising area of luminescence studies. In this work, white light emitting nanocrystals of cubic zirconia doped with Eu 3+ are synthesized by hydrothermal technique. The dopant Eu 3+ is used to stabilize crystalline phase to cubic and at the same time to get red counterpart of the white light. The synthesis procedure is simple and precursor required no further annealing for crystallization. X-ray diffraction patterns show the crystalline phase of ZrO 2 :Eu 3+ to be cubic and it is confirmed by Fourier Transform Infrared spectroscopy. From transmission electron microscopy images, size of the crystals is found to be ∼5 nm. Photoluminescence emission spectrum of the sample, on monitoring excitation at O 2− –Eu 3+ charge transfer state shows broad peak due to O 2− of the zirconia and that of Eu 3+ emission. Commission Internationale de l’éclairage co-ordinate of this nanocrystal (0.32, 0.34) is closed to that of the ideal white light (0.33, 0.33). Correlated color temperature of the white light (5894 K) is within the range of vertical daylight. Lifetime (1.32 ms) corresponding to 5 D 0 energy level of the Eu 3+ is found to be far longer than conventional red counterparts of white light emitters. It suggests that the ZrO 2 :Eu 3+ nanocrystals synthesized by hydrothermal technique may find applications in simulating the vertical daylight of the Sun

Atomistically-informed dislocation dynamics in FCC crystals

International Nuclear Information System (INIS)

Martinez, E.; Marian, J.; Arsenlis, A.; Victoria, M.; Martinez, E.; Victoria, M.; Perlado, J.M.

2008-01-01

Full text of publication follows. We will present a nodal dislocation dynamics (DD) model to simulate plastic processes in fcc crystals. The model explicitly accounts for all slip systems and Burgers vectors observed in fcc systems, including stacking faults and partial dislocations. We derive simple conservation rules that describe all partial dislocation interactions rigorously and allow us to model and quantify cross-slip processes, the structure and strength of dislocation junctions, and the formation of fcc-specific structures such as stacking fault tetrahedra. The DD framework is built upon isotropic non-singular linear elasticity, and supports itself on information transmitted from the atomistic scale. In this fashion, connection between the meso and micro scales is attained self-consistently with core parameters fitted to atomistic data. We perform a series of targeted simulations to demonstrate the capabilities of the model, including dislocation reactions and dissociations and dislocation junction strength. Additionally we map the four-dimensional stress space relevant for cross-slip and relate our fundings to the plastic behaviour of' monocrystalline fcc metals. (authors)

Machine-learning approach for local classification of crystalline structures in multiphase systems

Science.gov (United States)

Dietz, C.; Kretz, T.; Thoma, M. H.

2017-07-01

Machine learning is one of the most popular fields in computer science and has a vast number of applications. In this work we will propose a method that will use a neural network to locally identify crystal structures in a mixed phase Yukawa system consisting of fcc, hcp, and bcc clusters and disordered particles similar to plasma crystals. We compare our approach to already used methods and show that the quality of identification increases significantly. The technique works very well for highly disturbed lattices and shows a flexible and robust way to classify crystalline structures that can be used by only providing particle positions. This leads to insights into highly disturbed crystalline structures.

New developments in FCC catalysis

Energy Technology Data Exchange (ETDEWEB)

Kelkar, C.P. [BASF Corporation, Iselin, NJ (United States)

2011-07-01

Fluid catalytic cracking (FCC) unit is one of the primary boiling point reduction units in the refinery that converts longer chain crude oil to useful products such as distillate, gasoline and LPG. As the quality of feedstock deteriorates, while specifications on the product side are becoming more and more stringent, the FCC unit is being severely challenged. Over the past few years BASF has introduced two new platform technologies that will assist in this challenge. This paper will present an overview of those platforms and also provide a brief update on the research underway to mitigate the current REO crisis. (orig.)

Possible origin of the discrepancy in Peierls stresses of fcc metals: First-principles simulations of dislocation mobility in aluminum

Science.gov (United States)

Shin, Ilgyou; Carter, Emily A.

2013-08-01

Dislocation motion governs the strength and ductility of metals, and the Peierls stress (σp) quantifies dislocation mobility. σp measurements carry substantial uncertainty in face-centered cubic (fcc) metals, and σp values can differ by up to two orders of magnitude. We perform first-principles simulations based on orbital-free density functional theory (OFDFT) to calculate the most accurate currently possible σp for the motion of (1)/(2)111 dislocations in fcc Al. We predict the σps of screw and edge dislocations (dissociated in their equilibrium state) to be 1.9×10-4G and 4.9×10-5G, respectively (G is the shear modulus). These values fall within the range of measurements from mechanical deformation tests (10-4-10-5G). OFDFT also finds a new metastable structure for a screw dislocation not seen in earlier simulations, in which a dislocation core on the glide plane does not dissociate into partials. The corresponding σp for this undissociated dislocation is predicted to be 1.1×10-2G, which agrees with typical Bordoni peak measurements (10-2-10-3G). The calculated σps for dissociated and undissociated screw dislocations differ by two orders of magnitude. The presence of undissociated, as well as dissociated, screw dislocations may resolve the decades-long mystery in fcc metals regarding the two orders of magnitude discrepancy in σp measurements.

Determination of the crystallographic parameters of cubic-to-tetragonal martensitic transformation using the infinitesimal deformation approach and wechsler, lieberman, and read theory

Science.gov (United States)

Navruz, N.

2001-02-01

The aim of the present study is to discuss the infinitesimal deformation (ID) approach’s application and practical applicability. Therefore, ID theory was reformulated and applied to the face centered cubic (fcc) to body centered tetragonal (bct) martensitic transformation for the case of the (110) [bar 110] slip system as the lattice invariant shear (LIS). The analytical solutions for the habit plane orientation, the magnitude of the lattice invariant shear, the orientation relation between parent and product phases, etc. were derived for fcc to bct martensitic transformation in an Fe-7 pct Al-2 pct C alloy. In order to compare with phenomenological theory’s results, crystallographic parameters were also calculated by using Wechsler, Lieberman, and Read (W-L-R) phenomenological theory. Agreement between the two results obtained from ID approach and W-L-R theory was found to be excellent.

Unusually large unit cell of lipid bicontinuous cubic phase: towards nature's length scales

Science.gov (United States)

Kim, Hojun; Leal, Cecilia

Lipid bicontinuous cubic phases are of great interest for drug delivery, protein crystallization, biosensing, and templates for directing hard material assembly. Structural modulations of lipid mesophases regarding phase identity and unit cell size are often necessary to augment loading and gain pore size control. One important example is the need for unit cells large enough to guide the crystallization of bigger proteins without distortion of the templating phase. In nature, bicontinuous cubic constructs achieve unit cell dimensions as high as 300 nm. However, the largest unit cell of lipid mesophases synthesized in the lab is an order of magnitude lower. In fact, it has been predicted theoretically that lipid bicontinuous cubic phases of unit cell dimensions exceeding 30 nm could not exist, as high membrane fluctuations would damp liquid crystalline order. Here we report non-equilibrium assembly methods of synthesizing metastable bicontinuous cubic phases with unit cell dimensions as high as 70 nm. The phases are stable for very long periods and become increasingly ordered as time goes by without changes to unit cell dimensions. We acknowledge the funding source as a NIH.

QCD and $\\gamma\\,\\gamma$ studies at FCC-ee

CERN Document Server

Skands, Peter

2016-10-20

The Future Circular Collider (FCC) is a post-LHC project aiming at searches for physics beyond the SM in a new 80--100~km tunnel at CERN. Running in its first phase as a very-high-luminosity electron-positron collider (FCC-ee), it will provide unique possibilities for indirect searches of new phenomena through high-precision tests of the SM. In addition, by collecting tens of ab$^{-1}$ integrated luminosity in the range of center-of-mass energies $\\sqrt{s}$~=90--350~GeV, the FCC-ee also offers unique physics opportunities for precise measurements of QCD phenomena and of photon-photon collisions through, literally, billions of hadronic final states as well as unprecedented large fluxes of quasireal $\\gamma$'s radiated from the $\\rm e^+e^-$ beams. We succinctly summarize the FCC-ee perspectives for high-precision extractions of the QCD coupling, for detailed analyses of parton radiation and fragmentation, and for SM and BSM studies through $\\gamma\\gamma$ collisions.

Regeneration of Hydrotreating and FCC Catalysts

Energy Technology Data Exchange (ETDEWEB)

CM Wai; JG Frye; JL Fulton; LE Bowman; LJ Silva; MA Gerber

1999-09-30

Hydrotreating, hydrocracking, and fluid catalytic cracking (FCC) catalysts are important components of petroleum refining processes. Hydrotreating and hydrocracking catalysts are used to improve the yield of high-quality light oil fractions from heavier crude oil and petroleum feedstocks containing high levels of impurities. FCC catalysts improve the yield of higher octane gasoline from crude oil. Residuum hydrotreating and cracking catalysts are susceptible to irreversible deactivation caused by adsorption of sulfur and by metals impurities, such as vanadium and nickel. The gradual buildup of these impurities in a hydrotreating catalyst eventually plugs the pores and deactivates it. Nickel and vanadium adversely affect the behavior of cracking catalysts, reducing product yield and quality. Replacing deactivated catalysts represents a significant cost in petroleum refining. Equally important are the costs and potential liabilities associated with treating and disposing spent catalysts. For example, recent US Environmental Protection Agency rulings have listed spent hydrotreating and hydrorefining catalysts as hazardous wastes. FCC catalysts, though more easily disposed of as road-base or as filler in asphalt and cement, are still an economic concern mainly because of the large volumes of spent catalysts generated. New processes are being considered to increase the useful life of catalysts or for meeting more stringent disposal requirements for spent catalysts containing metals. This report discusses a collaborative effort between Pacific Northwest National Laboratory (PNNL) and Phillips Petroleum, Inc., to identify promising chemical processes for removing metals adhered to spent hydrodesulfurization (HDS, a type of hydrotreating catalyst) and FCC catalysts. This study, conducted by PNNL, was funded by the US Department of Energy's Bartlesville Project Office. Fresh and spent catalysts were provided by Phillips Petroleum. The FCC catalyst was a rare

Energy of the Isolated Metastable Iron-Nickel FCC Nanocluster with a Carbon Atom in the Tetragonal Interstice.

Science.gov (United States)

Bondarenko, Natalya V; Nedolya, Anatoliy V

2017-12-01

The energy of the isolated iron-nickel nanocluster was calculated by molecular mechanics method using Lennard-Jones potential. The cluster included a carbon atom that drifted from an inside octahedral interstice to a tetrahedral interstice in [Formula: see text] direction and after that in direction to the surface. In addition, one of 14 iron atoms was replaced by a nickel atom, the position of which was changing during simulation.The energy of the nanocluster was estimated at the different interatomic distances. As a result of simulation, the optimal interatomic distances of Fe-Ni-C nanocluster was chosen for the simulation, in which height of the potential barrier was maximal and face-centered cubic (FCC) nanocluster was the most stable.It is shown that there were three main positions of a nickel atom that significantly affected nanocluster's energy.The calculation results indicated that position of the carbon atom in the octahedral interstice was more energetically favorable than tetrahedral interstice in the case of FCC nanocluster. On the other side, the potential barrier was smaller in the direction [Formula: see text] than in the direction .This indicates that there are two ways for carbon atom to drift to the surface of the nanocluster.

Precision measurements of the top quark couplings at the FCC

CERN Document Server

AUTHOR|(CDS)2051271

2015-01-01

The design study of the Future Circular Colliders (FCC) in a 100-km ring in the Geneva area has started at CERN at the beginning of 2014, as an option for post-LHC particle accelerators. The study has an emphasis on proton-proton and electron-positron high-energy frontier machines. In the current plans, the first step of the FCC physics programme would exploit a high-luminosity e+e- collider called FCC-ee, with centre-of-mass energies ranging from below the Z pole to the t-tbar threshold and beyond, followed by 100\\,TeV proton-proton collisions as ultimate goal. When combined, these two steps offer a large palette of complementary measurements and sensitivity for new physics. In particular, the association of the FCC-ee and the FCC-hh allows measurements of the top-quark electroweak and Yukawa couplings to be performed with unrivaled precision.

Inelastic neutron scattering from high-density fcc 4He

International Nuclear Information System (INIS)

Thomlinson, W.; Eckert, J.; Shirane, G.

1978-01-01

The phonon dispersion relations in high-density crystals of fcc 4 He have been measured along high-symmetry directions by the neutron-inelastic-scattering technique. A recent study of the lattice dynamics of fcc 4 He by Eckert et al. has been extended to cover the fcc phase diagram at pressures below 5 kbar. Molar volumes of 9.03, 9.43, and 9.97 cm 3 /mole have been studied in the temperature range from near the melting curve to near the fcc-hcp transition line. The phonon dispersion relations are in good agreement with a first-order self-consistent phonon theory calculation by Goldman. The observed phonon-group line shapes at large energy and momentum transfers show evidence for multiphonon scattering in agreement with calculations by Glyde. Eckert et al. reported extremely large anharmonic isochoric temperature shifts of the phonon energies. The present work studied the shifts as a function of molar volume and temperature. Mode-Grueneisen-parameter dispersion curves have been measured using the present data and earlier measurements at lower density in the fcc phase by Traylor et al. Macroscopic Grueneisen parameters have been calculated from the phonon density of states obtained from the data

Structural and magnetic properties of Fe{sub x}Ni{sub 100−x} alloys synthesized using Al as a reducing metal

Energy Technology Data Exchange (ETDEWEB)

Srakaew, N. [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Jantaratana, P., E-mail: fscipsj@ku.ac.th [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Nipakul, P. [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Sirisathitkul, C. [Molecular Technology Research Unit, School of Science, Walailak University, Nakhon Si Thammarat 80161 (Thailand)

2017-08-01

Highlights: • Reduction by aluminum is a simple and safe route to synthesize iron-nickel alloys. • Alloy compositions with up to 90 at.% Fe can be obtained with minimal oxidation. • Morphology and magnetic properties are varied with the alloy composition. - Abstract: Iron-nickel (Fe-Ni) alloys comprising nine different compositions were rapidly synthesized from the redox reaction using aluminum foils as the reducing metal. Compared with conventional chemical syntheses, this simple approach is relatively safe and allows control over the alloy morphology and magnetic behavior as a function of the alloy composition with minimal oxidation. For alloys having low (10%–30%) Fe content the single face-centered cubic (FCC) FeNi{sub 3} phase was formed with nanorods aligned in the (1 1 1) crystalline direction on the cluster surface. This highly anisotropic morphology gradually disappeared as the Fe content was raised to 40%–70% with the alloy structure possessing a mixture of FCC FeNi{sub 3} and body-centered cubic (BCC) Fe{sub 7}Ni{sub 3}. The FCC phase was entirely replaced by the BCC structure upon further increase the Fe content to 80%–90%. The substitution of Ni by Fe in the crystals and the dominance of the BCC phase over the FCC structure gave rise to enhanced magnetization. By contrast, the coercive field decreased as a function of increasing Fe because of the reduction in shape anisotropy and the rise of saturation magnetization.

An atomic-scale model of fcc crystal-growth

Energy Technology Data Exchange (ETDEWEB)

Waal, B.W. van de (Technische Hogeschool Twente, Enschede (Netherlands). Dept. of Physics)

1991-01-01

Nearly perfect fcc growth may be simulated by the application of a simple growth-algorithm - only sites that are at least 4-coordinated are occupied - to a selected seed. The seed is a 22-atom cluster, being the smallest close-packed structure with two crossing stacking-faults. The stacking-faults produce active surface-sites, that can not be exhausted by occupation; they are arranged in non-vanishing steps, similar to those produced by screw-dislocations. The algorithm prevents further stacking-faults, and ensures ABC-stacking of close-packed (111)-layers, characteristic of the fcc structure. The same algorithm would not produce further growth of perfect fcc clusters or of Mackay icosahedra. It is proposed that the ability to grow fast under near-equilibrium conditions is a better criterion to select clusters as precursors of the bulk-structure than their cohesive energy. The crystal structure problem of the rare gases - why fcc, not hcp - is discussed in connection with the apparent impossibility to simulate hcp growth by an analogous procedure. (orig.).

First-principles study of nitrogen doping in cubic and amorphous Ge2Sb2Te5

Science.gov (United States)

Caravati, S.; Colleoni, D.; Mazzarello, R.; Kühne, T. D.; Krack, M.; Bernasconi, M.; Parrinello, M.

2011-07-01

We investigated the structural, electronic and vibrational properties of amorphous and cubic Ge2Sb2Te5 doped with N at 4.2 at.% by means of large scale ab initio simulations. Nitrogen can be incorporated in molecular form in both the crystalline and amorphous phases at a moderate energy cost. In contrast, insertion of N in the atomic form is very energetically costly in the crystalline phase, though it is still possible in the amorphous phase. These results support the suggestion that N segregates at the grain boundaries during the crystallization of the amorphous phase, resulting in a reduction in size of the crystalline grains and an increased crystallization temperature.

Liquid crystalline systems for transdermal delivery of celecoxib: in vitro drug release and skin permeation studies.

Science.gov (United States)

Estracanholli, Eder André; Praça, Fabíola Silva Garcia; Cintra, Ana Beatriz; Pierre, Maria Bernadete Riemma; Lara, Marilisa Guimarães

2014-12-01

Liquid crystalline systems of monoolein/water could be a promising approach for the delivery of celecoxib (CXB) to the skin because these systems can sustain drug release, improve drug penetration into the skin layers and minimize side effects. This study evaluated the potential of these systems for the delivery of CXB into the skin based on in vitro drug release and skin permeation studies. The amount of CXB that permeated into and/or was retained in the skin was assayed using an HPLC method. Polarizing light microscopy studies showed that liquid crystalline systems of monoolein/water were formed in the presence of CXB, without any changes in the mesophases. The liquid crystalline systems decreased drug release when compared to control solution. Drug release was independent of the initial water content of the systems and CXB was released from cubic phase systems, irrespective of the initial water content. The systems released the CXB following zero-order release kinetics. In vitro drug permeation studies showed that cubic phase systems allowed drug permeation and retention in the skin layers. Cubic phase systems of monoolein/water may be promising vehicles for the delivery of CXB in/through the skin because it improved CXB skin permeation compared with the control solution.

Application of Zeolitic Additives in the Fluid Catalytic Cracking (FCC

Directory of Open Access Journals (Sweden)

A. Nemati Kharat

2013-06-01

Full Text Available Current article describes application of zeolites in fluid catalytic cracking (FCC. The use of several zeolitic additives for the production light olefins and reduction of pollutants is described. Application of zeolites as fluid catalytic cracking (FCC catalysts and additives due to the presence of active acid sites in the zeolite framework  increase the formation of desired cracking products (i.e., olefin and branched products  in the FCC unit.

First-principles study of ternary fcc solution phases from special quasirandom structures

International Nuclear Information System (INIS)

Shin Dongwon; Wang Yi; Liu Zikui; Walle, Axel van de

2007-01-01

In the present work, ternary special quasirandom structures (SQSs) for a fcc solid solution phase are generated at different compositions, x A =x B =x C =(1/3) and x A =(1/2), x B =x C =(1/4), whose correlation functions are satisfactorily close to those of a random fcc solution. The generated SQSs are used to calculate the mixing enthalpy of the fcc phase in the Ca-Sr-Yb system. It is observed that first-principles calculations of all the binary and ternary SQSs in the Ca-Sr-Yb system exhibit very small local relaxation. It is concluded that the fcc ternary SQSs can provide valuable information about the mixing behavior of the fcc ternary solid solution phase. The SQSs presented in this work can be widely used to study the behavior of ternary fcc solid solutions

Physics case of FCC-ee

CERN Document Server

d'Enterria, David

2016-01-01

The physics case for electron-positron beams at the Future Circular Collider (FCC-ee) is succinctly summarized. The FCC-ee core program involves $e^+e^-$ collisions at $\\sqrt{s}$ = 90, 160, 240, and 350 GeV with multi-ab$^{-1}$ integrated luminosities, yielding about 10$^{12}$ Z bosons, 10$^{8}$ W$^+$W$^-$ pairs, 10$^{6}$ Higgs bosons and 4$\\cdot$10$^{5}$ $t\\bar{t}$ pairs per year. The huge luminosities combined with $\\cal{100}$ keV knowledge of the c.m. energy will allow for Standard Model studies at unrivaled precision. Indirect constraints on new physics can thereby be placed up to scales $\\Lambda_{_{\\rm NP}} \\approx$ 7 and 100 TeV for particles coupling respectively to the Higgs and electroweak bosons.

Electronic structure and superconductivity of fcc Cr

International Nuclear Information System (INIS)

Xu, J.; Freeman, A.J.; Jarlborg, T.; Brodsky, M.B.

1984-01-01

Results of self-consistent electronic structure calculations are reported for metastable fcc Cr metal. Unlike the case of bcc Cr which has E/sub F/ at a minimum in the density of states (DOS), the DOS at E/sub F/ in fcc Cr is at a peak making this one of the higher-DOS metals with the fcc structure (e.g., comparable with that of Ni and Pt). A calculated Stoner factor of 0.82 indicates that ferromagnetic ordering is not expected. Calculations of the electron-phonon coupling parameter lambda and superconducting transition temperature T/sub c/ were made using the rigid-ion approximation and strong-coupling theory with various estimates of the (unknown) phonon contribution. We conclude that T/sub c/'sroughly-equal2.5 K are reasonable, although they are substantially smaller than the T/sub c/roughly-equal10 K derived from measurements on Au-Cr-Au sandwiches

FCC-hh Hadron Collider - Parameter Scenarios and Staging Options

CERN Document Server

Benedikt, Michael; Schulte, Daniel; Zimmermann, F; Syphers, M J

2015-01-01

FCC-hh is a proposed future energy-frontier hadron collider, based on dipole magnets with a field around 16 T installed in a new tunnel with a circumference of about 100 km, which would provide proton collisions at a centre-of-mass energy of 100 TeV, as well as heavy-ion collisions at the equivalent energy. The FCC-hh should deliver a high integrated proton-proton luminosity at the level of several 100 fb−1 per year, or more. The challenges for operating FCC-hh with high beam current and at high luminosity include the heat load from synchrotron radiation in a cold environment, the radiation from collision debris around the interaction region, and machine protection. In this paper, starting from the FCC-hh design baseline parameters we explore different approaches for increasing the integrated luminosity, and discuss the impact of key individual pa- rameters, such as the turnaround time. We also present some injector considerations and options for early hadron-collider operation.

Dynamic optimization of a FCC converter unit: numerical analysis

Directory of Open Access Journals (Sweden)

E. Almeida Nt

2011-03-01

Full Text Available Fluidized-bed Catalytic Cracking (FCC is a process subject to frequent variations in the operating conditions (including feed quality and feed rate. The production objectives usually are the maximization of LPG and gasoline production. This fact makes the FCC converter unit an excellent opportunity for real-time optimization. The present work aims to apply a dynamic optimization in an industrial FCC converter unit, using a mechanistic dynamic model, and to carry out a numerical analysis of the solution procedure. A simultaneous approach was used to discretize the system of differential-algebraic equations and the resulting large-scale NLP problem was solved using the IPOPT solver. This study also does a short comparison between the results obtained by a potential dynamic real-time optimization (DRTO against a possible steady-state real-time optimization (RTO application. The results demonstrate that the application of dynamic real-time optimization of a FCC converter unit can bring significant benefits in production.

Database implementation to fluidized cracking catalytic-FCC process

International Nuclear Information System (INIS)

Santana, Antonio Otavio de; Dantas, Carlos Costa; Santos, Valdemir A. dos

2009-01-01

A process of Fluidized Cracking Catalytic (FCC) was developed by our research group. A cold model FCC unit, in laboratory scale, was used for obtaining of the data relative to the following parameters: air flow, system pressure, riser inlet pressure, rise outlet pressure, pressure drop in the riser, motor speed of catalyst injection and density. The measured of the density is made by gamma ray transmission. For the fact of the process of FCC not to have a database until then, the present work supplied this deficiency with the implementation of a database in connection with the Matlab software. The data from the FCC unit (laboratory model) are obtained as spreadsheet of the MS-Excel software. These spreadsheets were treated before importing them as database tables. The application of the process of normalization of database and the analysis done with the MS-Access in these spreadsheets treated revealed the need of an only relation (table) for to represent the database. The Database Manager System (DBMS) chosen has been the MS-Access by to satisfy our flow of data. The next step was the creation of the database, being built the table of data, the action query, selection query and the macro for to import data from the unit FCC in study. Also an interface between the application 'Database Toolbox' (Matlab2008a) and the database was created. This was obtained through the drivers ODBC (Open Data Base Connectivity). This interface allows the manipulation of the database by the users operating in the Matlab. (author)

Database implementation to fluidized cracking catalytic-FCC process

Energy Technology Data Exchange (ETDEWEB)

Santana, Antonio Otavio de; Dantas, Carlos Costa, E-mail: aos@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Santos, Valdemir A. dos, E-mail: valdemir.alexandre@pq.cnpq.b [Universidade Catolica de Pernambuco, Recife, PE (Brazil). Centro de Ciencia e Tecnologia

2009-07-01

A process of Fluidized Cracking Catalytic (FCC) was developed by our research group. A cold model FCC unit, in laboratory scale, was used for obtaining of the data relative to the following parameters: air flow, system pressure, riser inlet pressure, rise outlet pressure, pressure drop in the riser, motor speed of catalyst injection and density. The measured of the density is made by gamma ray transmission. For the fact of the process of FCC not to have a database until then, the present work supplied this deficiency with the implementation of a database in connection with the Matlab software. The data from the FCC unit (laboratory model) are obtained as spreadsheet of the MS-Excel software. These spreadsheets were treated before importing them as database tables. The application of the process of normalization of database and the analysis done with the MS-Access in these spreadsheets treated revealed the need of an only relation (table) for to represent the database. The Database Manager System (DBMS) chosen has been the MS-Access by to satisfy our flow of data. The next step was the creation of the database, being built the table of data, the action query, selection query and the macro for to import data from the unit FCC in study. Also an interface between the application 'Database Toolbox' (Matlab2008a) and the database was created. This was obtained through the drivers ODBC (Open Data Base Connectivity). This interface allows the manipulation of the database by the users operating in the Matlab. (author)

Beam Dynamics Challenges for FCC-ee

CERN Document Server

AUTHOR|(SzGeCERN)442987; Benedikt, Michael; Oide, Katsunobu; Bogomyagkov, Anton; Levichev, Evgeny; Migliorati, Mauro; Wienands, Uli

2015-01-01

The goals of FCC-ee include reaching luminosities of up to a few 1036 cm-2s-1 per interaction point at the Z pole or some 1034 cm-2s-1 at the ZH production peak, and pushing the beam energy up to ≥175 GeV, in a ring of 100 km circumference, with a total synchrotron-radiation power not exceeding 100 MW. A parameter baseline as well as high-luminosity crab-waist options were described in [1] and [2], respectively. The extremely high luminosity and resulting short beam lifetime (due to radiative Bhabha scattering) are sustained by top-up injection. The FCC-ee design status and typical beam parameters for different modes of operation are reported in [3]. One distinct feature of the FCC-ee design is its conception as a double ring, with separate beam pipes for the two counter-rotating (electron and positron) beams, resembling, in this aspect, the high-luminosity B factories PEP-II, KEKB and SuperKEKB as well as the LHC. The two separate rings do not only permit operation with a large number of bunches, up to a f...

Impact of FCC regenerator design in the NOx emissions

Energy Technology Data Exchange (ETDEWEB)

Pereira, Hugo Borges; Sandes, Emanuel Freire; Gilbert, William Richard; Roncolatto, Rodolfo Eugenio; Gobbo, Rodrigo; Casavechia, Luiz Carlos; Candido, William Victor Carlos [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Bridi, Patricia Elaine [Possebon Engenharia, Sao Mateus do Sul, PR (Brazil)

2012-07-01

Fluid Catalytic Cracking (FCC) is the main point source of NOx in the refinery and it is responsible for at least 20% of the total NOx emissions from the refineries. The thermal NOx formation in the FCC regenerator is negligible. However, half of the feed nitrogen is converted to coke, and is burned in the regenerator. The majority of coke nitrogen is reduced to N2 and less than 10% is converted to NOx. This number may vary significantly with the oxygen excess in the flue gas and other operational conditions. With the purpose of evaluating the impact of different regenerator designs in NOx formation, several tests were carried out in the PETROBRAS FCC prototype unit. The test unit is equipped with adiabatic insulation and a CO boiler, allowing it to reproduce the heat balance of a commercial FCC and to operate either in full combustion or partial combustion. Two different designs of FCC regenerators were evaluated: single stage regenerator (the existing configuration) and two stage regenerator, with the catalyst bed divided into two sections by a structured packing baffle. It was observed in the tests that the combustion regime had a very strong effect on NOx formation. In full combustion, the effect of the FCC operating variables: excess oxygen, combustion promoter content in catalyst and regenerator design could be identified. The two stage configuration was capable of decreasing NOx emissions by 30%. In partial combustion, the effect of the CO-boiler variables on NOx emissions was overwhelming, but the use of the structured packing baffle was able to improve the catalyst regeneration.(author)

Neutron Scattering from fcc Pr and Pr3Tl

DEFF Research Database (Denmark)

Birgeneau, R. J.; Als-Nielsen, Jens Aage; Bucher, E.

1972-01-01

Elastic-neutron-scattering measurements on the singlet-ground-state ferromagnets fcc Pr and Pr3 Tl are reported. Both exhibit magnetic phase transitions, possibly to a simple ferromagnetic state at 20 and 11.6 °K, respectively. The transitions appear to be of second order although that in fcc Pr...

Quasi-crystalline geometry for architectural structures

DEFF Research Database (Denmark)

Wester, Ture; Weinzieri, Barbara

The quasi-crystal (QC) type of material was discovered in 1983 by Dan Schechtman from Technion, Haifa. This new crystalline structure of material broke totally with the traditional conception of crystals and geometry introducing non-periodic close packing of cells with fivefold symmetry in 3D space....... The quasi-crystal geometry can be constructed from two different cubic cells with identical rhombic facets, where the relation between the diagonals is the golden section. All cells have identical rhombic faces, identical edges and identical icosahedral/dodecahedral nodes....

Stacking fault density and bond orientational order of fcc ruthenium nanoparticles

Science.gov (United States)

Seo, Okkyun; Sakata, Osami; Kim, Jae Myung; Hiroi, Satoshi; Song, Chulho; Kumara, Loku Singgappulige Rosantha; Ohara, Koji; Dekura, Shun; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi

2017-12-01

We investigated crystal structure deviations of catalytic nanoparticles (NPs) using synchrotron powder X-ray diffraction. The samples were fcc ruthenium (Ru) NPs with diameters of 2.4, 3.5, 3.9, and 5.4 nm. We analyzed average crystal structures by applying the line profile method to a stacking fault model and local crystal structures using bond orientational order (BOO) parameters. The reflection peaks shifted depending on rules that apply to each stacking fault. We evaluated the quantitative stacking faults densities for fcc Ru NPs, and the stacking fault per number of layers was 2-4, which is quite large. Our analysis shows that the fcc Ru 2.4 nm-diameter NPs have a considerably high stacking fault density. The B factor tends to increase with the increasing stacking fault density. A structural parameter that we define from the BOO parameters exhibits a significant difference from the ideal value of the fcc structure. This indicates that the fcc Ru NPs are highly disordered.

Workshop summary, future prospects and FCC-ee impact on $\\alpha_s$

CERN Document Server

d'Enterria, David

2015-01-01

The workshop on “High-precision α s measurements from LHC to FCC-ee” –organized in the con- text of the preparation of the Future Circular Collider (FCC) Conceptual Design Report, within the FCC-e + e − “QCD and photon-photon” physics working group activities– discussed the latest advances in the measurement of the strong interaction coupling α s . The meeting brought together leading experts in the field to explore in depth recent theoretical and experimental developments on the determination of α s , new ways to measure this coupling in lepton-lepton, lepton-hadron and hadron-hadron collisions, and in particular the improvements expected at the proposed Future Circular Collider e + e − (FCC-ee) facility.

Stress induced martensitic transformation from bcc to fcc in Ag-Zn

International Nuclear Information System (INIS)

Takezawa, K.; Akamatsu, R.; Marukawa, K.

1995-01-01

The martensitic transformation in Ag-Zn alloys of low-Zn content has been studied by optical and electron microscopic observations and by tensile tests. The β 1 phase of B2 structure transforms to the thermo-elastic martensite having 9R structure similar to Cu-based alloys upon cooling to temperature below Ms. When the β 1 phase is stretched at room temperature, the slip deformation occurs at first and then the stress-induced martensite(SIM) of wedge-like morphology forms. The SIM has the ordered fcc structure containing micro-twins. This direct transformation from bcc to fcc is a unique feature in Ag-Zn alloys. In Cu alloys, martensites of fcc structure appear only after the second transformation from the first transformation product of 9R structure. The critical stress for the martensitic transformation and a degree of order of SIM decrease as the deformation temperature rises. In Ag-Zn alloys, the martensite of disordered fcc is thermally produced also by up-quenching to a higher temperature. In the present study, the relation between martensites of ordered and disordered fcc is discussed through thermodynamical calculations. The condition for the direct transformation from bcc to fcc is also examined. (orig.)

Phase change behaviors of Zn-doped Ge2Sb2Te5 films

International Nuclear Information System (INIS)

Wang Guoxiang; Nie Qiuhua; Shen Xiang; Fu Jing; Xu Tiefeng; Dai Shixun; Wang, R. P.; Wu Liangcai

2012-01-01

Zn-doped Ge 2 Sb 2 Te 5 phase-change materials have been investigated for phase change memory applications. Zn 15.16 (Ge 2 Sb 2 Te 5 ) 84.84 phase change film exhibits a higher crystallization temperature (∼258 °C), wider band gap (∼0.78 eV), better data retention of 10 years at 167.5 °C, higher crystalline resistance, and faster crystallization speed compared with the conventional Ge 2 Sb 2 Te 5 . The proper Zn atom added into Ge 2 Sb 2 Te 5 serves as a center for suppression of the face-centered-cubic (fcc) phase to hexagonal close-packed (hcp) phase transition, and fcc phase has high thermal stability partially due to the bond recombination among Zn, Sb, and Te atoms.

FCC catalyst technologies expand limits of process capability

International Nuclear Information System (INIS)

Leiby, S.

1992-01-01

This paper reports that over the past 30 or so years, many improvements in fluid catalytic cracking (FCC) operation have been achieved as the result of innovations in catalyst formulation. During the 1990s, new environmental regulations on issues such as reformulated gasoline will place new demands on both the refining industry and catalyst suppliers. An overview of cracking catalyst technology therefore seems in order. Today, high-technology innovations by catalyst manufacturers are rapid, but profit margins are slim. Catalyst formulations are shrouded in secrecy and probably depend almost as much on art as on science. Special formulations for specific cracking applications get the greatest emphasis today. To illustrate this point, OGJ's Worldwide Catalyst Report lists over 200 FCC catalyst designations. Catalysts containing components to enhance gasoline octane now account for about 70% of total U.S. FCC catalyst usage

Cross-talk studies between FCC-hh Experimental Interaction Regions

CERN Document Server

AUTHOR|(CDS)2081283; Seryi, Andrei; Appleby, Robert Barrie; Rafique, Haroon; Besana, Maria Ilaria

2017-01-01

Debris from 50 TeV proton-proton collisions at the main interaction point in the FCC-hh may contribute to the background in the subsequent detector. This cross-talk is of possible concern for the FCC-hh due to the high luminosity and energy of the collider. DPMJET-III is used as a collision debris generator in order to assess the muon cross-talk contribution. An analytical calculation of muon range in rock is performed. This is followed by a full Monte Carlo simulation using FLUKA, where the accelerator tunnel has been modelled. The muon cross talk between the adjacent interaction points is assessed and its implications for FCC-hh design are discussed.

FCC Official Brochure - 2016

CERN Multimedia

Charitos, Panagiotis

2016-01-01

The FCC brochure describes the main scope of the study and give more information about the main scenarios explored under the study. It also highlights the R&D efforts under the study that will go into a Conceptual Design Report. Finally, it offers more information about the collaboration and a list of useful contact details.

FCC-ee accelerator parameters, performance and limitations

CERN Document Server

Koratzinos, Mike

2016-12-22

CERN has recently launched the Future Circular Collider (FCC) study to deal with all aspects of an ambitious post-LHC possible programme. The emphasis of the study is on a 100 TeV proton collider to be housed in a 80-100 km new ring in the Geneva region. An electron machine will also be considered as a possible intermediate first step (FCC-ee). The study benefits from earlier work done in the context of TLEP and has already published a parameter table, to serve as the basis for the work to be done. The study aims to publish a conceptual design report at around 2018. The recent discovery of a light Higgs boson has opened up considerable interest in circular e+e- Higgs factories around the world. FCC-ee is capable of very high luminosities in a wide centre-of-mass (ECM) spectrum from 90 to 350 GeV. This allows the very precise study of the Z, W and H bosons as well as the top quark, allowing for meaningful precision tests of the closure of the Standard Model.

Beam Optics for FCC-ee Collider Ring

CERN Document Server

Oide, Katsunobu; Aumon, S; Benedikt, M; Blondel, A; Bogomyagkov, A V; Boscolo, M; Burkhardt, H; Cai, Y; Doblhammer, A; Haerer, B; Holzer, B; Koop, I; Koratzinos, M; Jowett, John M; Levichev, E B; Medina, L; Ohmi, K; Papaphilippou, Y; Piminov, P A; Shatilov, D N; Sinyatkin, S V; Sullivan, M; Wenninger, J; Wienands, U; Zhou, D; Zimmermann, F

2017-01-01

A beam optics scheme has been designed [ 1 ] for the Future Circular Collider- e + e − (FCC-ee). The main characteristics of the design are: beam energy 45 to 175 GeV, 100 km circumference with two interaction points (IPs) per ring, horizontal crossing angle of 30 mrad at the IP and the crab-waist scheme [ 2 ] with local chromaticity correction. The crab-waist scheme is implemented within the local chromaticity correction system without additional sextupoles, by reducing the strength of one of the two sextupoles for vertical chromatic correction at each side of the IP. So- called “tapering" of the magnets is applied, which scales all fields of the magnets according to the local beam energy to compensate for the effect of synchrotron radiation (SR) loss along the ring. An asymmetric layout near the interaction region reduces the critical energy of SR photons on the incoming side of the IP to values below 100 keV, while matching the geometry to the beam line of the FCC proton collider (FCC-hh) [ 3 ] as clos...

Different magnetic properties of rhombohedral and cubic Ni2+ doped indium oxide nanomaterials

Directory of Open Access Journals (Sweden)

Qingbo Sun

2011-12-01

Full Text Available Transition metal ions doped indium oxide nanomaterials were potentially used as a kind of diluted magnetic semiconductors in transparent spintronic devices. In this paper, the influences of Ni2+ doped contents and rhombohedral or cubic crystalline structures of indium oxide on magnetic properties were investigated. We found that the magnetic properties of Ni2+ doped indium oxide could be transferred from room temperature ferromagnetisms to paramagnetic properties with increments of doped contents. Moreover, the different crystalline structures of indium oxide also greatly affected the room temperature ferromagnetisms due to different lattice constants and almost had no effects on their paramagnetic properties. In addition, both the ferromagnetic and paramagnetic properties were demonstrated to be intrinsic and not caused by impurities.

Plasma deposition of cubic boron nitride films from non-toxic material at low temperatures

International Nuclear Information System (INIS)

Karim, M.Z.; Cameron, D.C.; Murphy, M.J.; Hashmi, M.S.J.

1991-01-01

Boron nitride has become the focus of a considerable amount of interest because of its properties which relate closely to those of carbon. In particular, the cubic nitride phase has extreme hardness and very high thermal conductivity similar to the properties of diamond. The conventional methods of synthesis use the highly toxic and inflammable gas diborane (B 2 H 6 ) as the reactant material. A study has been made of the deposition of thin films of boron nitride (BN) using non-toxic material by the plasma-assisted chemical vapour deposition technique. The source material was borane-ammonia (BH 3 -NH 3 ) which is a crystalline solid at room temperature with a high vapour pressure. The BH 3 -NH 3 vapour was decomposed in a 13.56 MHz nitrogen plasma coupled either inductively or capacitively with the system. The composition of the films was assessed by measuring their IR absorption when deposited on silicon and KBr substrates. The hexagonal (graphitic) and cubic (diamond-like) allotropes can be distinguished by their characteristic absorption bands which occur at 1365 and 780 cm -1 (hexagonal) and 1070 cm -1 (cubic). We have deposited BN films consisting of a mixture of hexagonal and cubic phases; the relative content of the cubic phase was found to be directly dependent on r.f. power and substrate bias. (orig.)

Anisotropy-based crystalline oxide-on-semiconductor material

Science.gov (United States)

McKee, Rodney Allen; Walker, Frederick Joseph

2000-01-01

A semiconductor structure and device for use in a semiconductor application utilizes a substrate of semiconductor-based material, such as silicon, and a thin film of a crystalline oxide whose unit cells are capable of exhibiting anisotropic behavior overlying the substrate surface. Within the structure, the unit cells of the crystalline oxide are exposed to an in-plane stain which influences the geometric shape of the unit cells and thereby arranges a directional-dependent quality of the unit cells in a predisposed orientation relative to the substrate. This predisposition of the directional-dependent quality of the unit cells enables the device to take beneficial advantage of characteristics of the structure during operation. For example, in the instance in which the crystalline oxide of the structure is a perovskite, a spinel or an oxide of similarly-related cubic structure, the structure can, within an appropriate semiconductor device, exhibit ferroelectric, piezoelectric, pyroelectric, electro-optic, ferromagnetic, antiferromagnetic, magneto-optic or large dielectric properties that synergistically couple to the underlying semiconductor substrate.

Single-crystal FCC and DHCP phases in Ce/Pr superlattices

International Nuclear Information System (INIS)

Lee, S.; Goff, J.P.; Ward, R.C.C.; Wells, M.R.; McIntyre, G.J.

2002-01-01

Cerium usually comprises a mixture of polycrystalline FCC and DHCP allotropes. Single-crystal Ce has been stabilised in Ce/Pr superlattices grown using molecular beam epitaxy. It is found that FCC or DHCP phases can be obtained depending on superlattice composition and growth conditions. Low-temperature neutron scattering was performed on Ce/Pr samples using the triple-axis spectrometer D10 at the ILL. Such measurements revealed one sample, [Ce 20 Pr 20 ] 60 , to be a single crystal with a DHCP unit cell; while another, [Ce 30 Pr 10 ] 56 , was a mixture of FCC and DHCP phases. Antiferromagnetic ordering of magnetic moments was observed in the DHCP sample (T N =11.1 K) with a magnetic structure similar to that found in bulk β-Ce. Surprisingly, the magnetic ordering was found to be confined to single Ce blocks. Furthermore, it was found that, at low temperatures, the lattice contraction observed for bulk FCC Ce was suppressed in Ce/Pr superlattices. (orig.)

First-principles study of nitrogen doping in cubic and amorphous Ge{sub 2}Sb{sub 2}Te{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Caravati, S; Mazzarello, R; Kuehne, T D; Parrinello, M [Computational Science, Department of Chemistry and Applied Biosciences, ETH Zurich, USI Campus, Via Giuseppe Buffi 13, CH-6900 Lugano (Switzerland); Colleoni, D; Bernasconi, M [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via R Cozzi 53, I-20125 Milano (Italy); Krack, M [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

2011-07-06

We investigated the structural, electronic and vibrational properties of amorphous and cubic Ge{sub 2}Sb{sub 2}Te{sub 5} doped with N at 4.2 at.% by means of large scale ab initio simulations. Nitrogen can be incorporated in molecular form in both the crystalline and amorphous phases at a moderate energy cost. In contrast, insertion of N in the atomic form is very energetically costly in the crystalline phase, though it is still possible in the amorphous phase. These results support the suggestion that N segregates at the grain boundaries during the crystallization of the amorphous phase, resulting in a reduction in size of the crystalline grains and an increased crystallization temperature.

Future Circular Collider Study FCC-he Baseline Parameters

CERN Document Server

Bruning, Oliver; Klein, Max; Pellegrini, Dario; Schulte, Daniel; Zimmermann, Frank

2017-01-01

Initial considerations are presented on the FCC-he, the electron-hadron collider con guration within the Future Circular Collider study. This note considers arguments for the choice of the electron beam energy based on physics, ep scattering kinematics and cost. The default con guration for the electron accelerator, as for the LHeC, is chosen to be a multi-turn energy recovery linac external to the proton beam tunnel. The main accelerator parameters of the FCC-he are discussed, assuming the concurrent operation of ep with the 100TeV cms energy pp collider. These are compared with the LHeC design concept, for increased performance as for a Higgs facility using the HL-LHC, and also the high energy HE-LHC ep collider configuration. Initial estimates are also provided for the luminosity performance of electron-ion colliders for the 60 GeV electron ERL when combined with the LHC, the HE-LHC and the FCC ion beams.

Phonon dispersion curves of fcc La

International Nuclear Information System (INIS)

Stassis, C.; Loong, C.; Zarestky, J.

1982-01-01

Large single crystals of fcc La were grown in situ and were used to study the lattice dynamics of this phase of La by coherent inelastic neutron scattering. The phonon dispersion curves have been measured along the [xi00], [xixi0], [xixixi], and [0xi1] symmetry directions at 660 and 1100 K. The T[xixixi] branch exhibits anomalous dispersion for xi>0.25 and, in addition, close to the zone boundary, the phonon frequencies of this branch decrease with decreasing temperature. This soft-mode behavior may be related to the #betta→α# transformation in La, an assumption supported by recent band-theoretical calculations of the generalized susceptibility of fcc La. At X the frequencies of the L[xi00] branch are considerably lower than those of the corresponding branch of #betta#-Ce; a similar but not as pronounced effect is observed for the frequencies of the L[xixixi] branch close to the point L. Since the calculated generalized susceptibility of fcc La exhibits strong peaks at X and L, these anomalies may be due to the renormalization of the phonon frequencies by virtual fbold-arrow-left-rightd transitions to the unoccupied 4f level in La. The data were used to evaluate the elastic constants, the phonon density of states, and the lattice specific heat at constant pressure C/sub P//sup

Cubical local partial orders on cubically subdivided spaces - existence and construction

DEFF Research Database (Denmark)

Fajstrup, Lisbeth

The geometric models of Higher Dimensional Automata and Dijkstra's PV-model are cubically subdivided topological spaces with a local partial order. If a cubicalization of a topological space is free of immersed cubic Möbius bands, then there are consistent choices of direction in all cubes, such ...... that the underlying geometry of an HDA may be quite complicated....

Cubical local partial orders on cubically subdivided spaces - Existence and construction

DEFF Research Database (Denmark)

Fajstrup, Lisbeth

2006-01-01

The geometric models of higher dimensional automata (HDA) and Dijkstra's PV-model are cubically subdivided topological spaces with a local partial order. If a cubicalization of a topological space is free of immersed cubic Möbius bands, then there are consistent choices of direction in all cubes...... that the underlying geometry of an HDA may be quite complicated....

47 CFR 2.926 - FCC identifier.

Science.gov (United States)

2010-10-01

... representative may receive a grantee code electronically via the Internet at https://gullfoss2.fcc.gov/prod/oet... which has not been granted equipment authorization where such grant is required prior to marketing...

Effect of the coupling between electronic structure and crystalline structure on some properties of transition metals

International Nuclear Information System (INIS)

Nastar, M.

1994-01-01

The elastic constants, energetic stabilities and vacancy formation energies in transition metals are calculated within a Tight Binding model. In order to outline the effect of the electronic structure, these properties are represented as functions of band filling. The variation of the shear elastic constants of hexagonal close packed (HCP), body centered cubic (BCC) and face centered cubic (FCC) structures, is in contrast with the roughly parabolic behavior of bulk modulus. The general trends are in very good agreement with available experimental and 'ab initio' data. The vacancy formation energy in the BCC structure shows strong deviations from bell shape behavior with a maximum corresponding approximately to the band filling of group 6. This band filling effect contributes to the noticeable decrease of the self diffusion rate between group 4 and group 6. We demonstrate that the abrupt increase of the C' elastic constant, the NT 1 (0.-1.1) phonon frequency, the energy differences between BCC and HCP and between FCC and HCP as well as the vacancy formation energy, that occurs when going from Zr to Mo, is related to the presence of a pseudo-gap in the density of states of the BCC structure. Using the recursion method, we show that the general trends of these properties are correctly reproduced when considering only a few moments of the density of states (about 6). On the other hand, details such as the elastic constant singularities, are displayed only with an exact calculation of the density of states. (Author). 173 refs., 84 figs., 5 tabs

Crystalline and amorphous carbon nitride films produced by high-energy shock plasma deposition

International Nuclear Information System (INIS)

Bursilll, L.A.; Peng, Julin; Gurarie, V.N.; Orlov, A.V.; Prawer, S.

1995-01-01

High-energy shock plasma deposition techniques are used to produce carbon-nitride films containing both crystalline and amorphous components. The structures are examined by high-resolution transmission electron microscopy, parallel-electron-energy loss spectroscopy and electron diffraction. The crystalline phase appears to be face-centered cubic with unit cell parameter approx. a=0.63nm and it may be stabilized by calcium and oxygen at about 1-2 at % levels. The carbon atoms appear to have both trigonal and tetrahedral bonding for the crystalline phase. There is PEELS evidence that a significant fraction of the nitrogen atoms have sp 2 trigonal bonds in the crystalline phase. The amorphous carbon-nitride film component varies from essentially graphite, containing virtually no nitrogen, to amorphous carbon-nitride containing up to 10 at % N, where the fraction of sp 3 bonds is significant. 15 refs., 5 figs

Site occupation state of deuterium atoms in fcc Fe

International Nuclear Information System (INIS)

Aoki, Katsutoshi; Machida, Akihiko; Saitoh, Hiroyuki; Hattori, Takanori; Sano-Furukawa, Asami

2015-01-01

The deuterization process of fcc Fe to form solid-solution fcc FeD x was investigated by in situ neutron diffraction measurements at high temperature and high pressure. In a completely deuterized specimen at 988 K and 6.3 GPa, deuterium atoms occupy the octahedral and tetrahedral interstitial sites with an occupancy of 0.532(9) and 0.056(5), respectively, giving a deuterium composition x of 0.64(1). During deuterization, the metal-lattice expands approximately linearly with deuterium composition at a rate of 2.21 Å 3 per deuterium atom. The minor occupation of tetrahedral site is likely driven by the intersite movement of deuterium atoms along the <111> direction in the fcc metal lattice. These results provide implications for the light elements in the Earth's core and the mechanism of hydrogen embrittlement of ferrous metals. (author)

The theoretical tensile strength of fcc crystals predicted from shear strength calculations

International Nuclear Information System (INIS)

Cerny, M; Pokluda, J

2009-01-01

This work presents a simple way of estimating uniaxial tensile strength on the basis of theoretical shear strength calculations, taking into account its dependence on a superimposed normal stress. The presented procedure enables us to avoid complicated and time-consuming analyses of elastic stability of crystals under tensile loading. The atomistic simulations of coupled shear and tensile deformations in cubic crystals are performed using first principles computational code based on pseudo-potentials and the plane wave basis set. Six fcc crystals are subjected to shear deformations in convenient slip systems and a special relaxation procedure controls the stress tensor. The obtained dependence of the ideal shear strength on the normal tensile stress seems to be almost linearly decreasing for all investigated crystals. Taking these results into account, the uniaxial tensile strength values in three crystallographic directions were evaluated by assuming a collapse of the weakest shear system. Calculated strengths for and loading were found to be mostly lower than previously calculated stresses related to tensile instability but rather close to those obtained by means of the shear instability analysis. On the other hand, the strengths for loading almost match the stresses related to tensile instability.

Inverse gold photonic crystals and conjugated polymer coated opals for functional materials

Energy Technology Data Exchange (ETDEWEB)

Landon, P.B.; Gutierrez, Jose; Ferraris, John P.; Martinez, I.L.; Giridharagopal, Rajiv; Wu, Y.-C.; Lee, Sergey; Parikh, Kunjal; Gillespie, Jessica; Ussery, Geoffrey; Karimi, Behzad; Baughman, Ray; Zakhidov, Anvar; Glosser, R

2003-10-01

Inverse gold photonic crystals templated from synthetic opals with a face centered cubic (FCC) crystal lattice were constructed by heat converting gold chloride to metallic gold. Tetrahedral formations constructed of alternating large and small octahedrons oriented in the zinc sulfide structure were created by controlling the infiltration of gold chloride. Silica spheres were coated with polyanilinesulfonic acid, polypyrrole, poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and 5 nm colloidal gold. Ordinary yeast cells were coated with polyanilinesulfonic acid, polypyrrole and 5 nm colloidal gold. Spheres coated with MEH-PPV were dispersed in H{sub 2}O and coated with polyelectrolytes which recharged and sterically stabilized the colloidal surfaces. The recharged spheres self-assembled by sedimentation with a FCC crystalline lattice possessing 500 {mu}m wide and 1 mm long crystallites. Silica spheres with diameters as large as 1500 {mu}m were self-assembled along the [1 0 0] direction of the FCC crystal lattice. Opals infiltrated with gold and opals constructed from polymer coated spheres were co-infiltrated with polypropylene yielding inverse polypropylene composite photonic crystals.

Theoretical investigations of the bulk modulus in the tetra-cubic transition of PbTiO3 material

Directory of Open Access Journals (Sweden)

Renan A. P. Ribeiro

2014-01-01

Full Text Available Resulting from ion displacement in a solid under pressure, piezoelectricity is an electrical polarization that can be observed in perovskite-type electronic ceramics, such as PbTiO3, which present cubic and tetragonal symmetries at different pressures. The transition between these crystalline phases is determined theoretically through the bulk modulus from the relationship between material energy and volume. However, the change in the material molecular structure is responsible for the piezoelectric effect. In this study, density functional theory calculations using the Becke 3-Parameter-Lee-Yang-Parr hybrid functional were employed to investigate the structure and properties associated with the transition state of the tetragonal-cubic phase change in PbTiO3 material.

Production of crystalline refractory metal oxides containing colloidal metal precipitates and useful as solar-effective absorbers

Science.gov (United States)

Narayan, Jagdish; Chen, Yok

1983-01-01

This invention is a new process for producing refractory crystalline oxides having improved or unusual properties. The process comprises the steps of forming a doped-metal crystal of the oxide; exposing the doped crystal in a bomb to a reducing atmosphere at superatmospheric pressure and a temperature effecting precipitation of the dopant metal in the crystal lattice of the oxide but insufficient to effect net diffusion of the metal out of the lattice; and then cooling the crystal. Preferably, the cooling step is effected by quenching. The process forms colloidal precipitates of the metal in the oxide lattice. The process may be used, for example, to produce thermally stable black MgO crystalline bodies containing magnetic colloidal precipitates consisting of about 99% Ni. The Ni-containing bodies are solar-selective absorbers, having a room-temperature absorptivity of about 0.96 over virtually all of the solar-energy spectrum and exhibiting an absorption edge in the region of 2 .mu.m. The process parameters can be varied to control the average size of the precipitates. The process can produce a black MgO crystalline body containing colloidal Ni precipitates, some of which have the face-centered-cubic structure and others of which have the body-centered cubic structure. The products of the process are metal-precipitate-containing refractory crystalline oxides which have improved or unique optical, mechanical, magnetic, and/or electronic properties.

FCC riser quick separation system: a review

Directory of Open Access Journals (Sweden)

Zhi Li

2016-10-01

Full Text Available Abstract The riser reactor is the key unit in the fluid catalytic cracking (FCC process. As the FCC feedstocks become heavier, the product mixture of oil, gas and catalysts must be separated immediately at the outlet of the riser to avoid excessive coking. The quick separation system is the core equipment in the FCC unit. China University of Petroleum (Beijing has developed many kinds of separation system including the fender-stripping cyclone and circulating-stripping cyclone systems, which can increase the separation efficiency and reduce the pressure drop remarkably. For the inner riser system, a vortex quick separation system has been developed. It contains a vortex quick separator and an isolated shell. In order to reduce the separation time, a new type of separator called the short residence time separator system was developed. It can further reduce the separation time to less than 1 s. In this paper, the corresponding design principles, structure and industrial application of these different kinds of separation systems are reviewed. A system that can simultaneously realize quick oil gas separation, quick oil gas extraction and quick pre-stripping of catalysts at the end of the riser is the trend in the future.

Dependence of Fracture Toughness on Crystallographic Orientation in Single-Crystalline Cubic (β) Silicon Carbide

Energy Technology Data Exchange (ETDEWEB)

Pharr, M.; Katoh, Y.; Bei, H.

2006-01-01

Along with other desirable properties, the ability of silicon carbide (SiC) to retain high strength after elevated temperature exposures to neutron irradiation renders it potentially applicable in fusion and advanced fission reactors. However, properties of the material such as room temperature fracture toughness must be thoroughly characterized prior to such practical applications. The objective of this work is to investigate the dependence of fracture toughness on crystallographic orientation for single-crystalline β-SiC. X-ray diffraction was first performed on the samples to determine the orientation of the crystal. Nanoindentation was used to determine a hardness of 39.1 and 35.2 GPa and elastic modulus of 474 and 446 GPa for the single-crystalline and polycrystalline samples, respectively. Additionally, crack lengths and indentation diagonals were measured via a Vickers micro-hardness indenter under a load of 100 gf for different crystallographic orientations with indentation diagonals aligned along fundamental cleavage planes. Upon examination of propagation direction of cracks, the cracks usually did not initiate and propagate from the corners of the indentation where the stresses are concentrated but instead from the indentation sides. Such cracks clearly moved along the {1 1 0} family of planes (previously determined to be preferred cleavage plane), demonstrating that the fracture toughness of SiC is comparatively so much lower along this set of planes that the lower energy required to cleave along this plane overpowers the stress-concentration at indentation corners. Additionally, fracture toughness in the <1 1 0> direction was 1.84 MPa·m1/2, lower than the 3.46 MPa·m1/2 measured for polycrystalline SiC (which can serve as an average of a spectrum of orientations), further demonstrating that single-crystalline β-SiC has a strong fracture toughness anisotropy.

Direct measurement of alpha_QED(mZ)at the FCC-ee

CERN Document Server

Janot, Patrick

2016-02-08

When the measurements from the FCC-ee become available, an improved determination of the standard-model "input" parameters will be needed to fully exploit the new precision data towards either constraining or fitting the parameters of beyond-the-standard-model theories. Among these input parameters is the electromagnetic coupling constant estimated at the Z mass scale, alpha_QED(mZ). The measurement of the muon forward- backward asymmetry at the FCC-ee, just below and just above the Z pole, can be used to make a direct determination of alpha_QED(mZ) with an accuracy deemed adequate for an optimal use of the FCC-ee precision data.

Preparation and electrochemical performances of cubic shape Cu2O as anode material for lithium ion batteries

International Nuclear Information System (INIS)

Zhang, C.Q.; Tu, J.P.; Huang, X.H.; Yuan, Y.F.; Chen, X.T.; Mao, F.

2007-01-01

Cubic and star-shaped crystalline Cu 2 O particles were synthesized by reducing the copper citrate complex solution with glucose. The microstructure and morphology of the Cu 2 O were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the Cu 2 O as anode materials for lithium ion batteries were measured by galvanostatic charge-discharge tests. The as-synthesized Cu 2 O particles were 1-2 μm with narrow distribution and the shape of Cu 2 O particles had an effect on the electrochemical properties. The cubic Cu 2 O particles delivered a higher reversible discharge capacity (390 mAh g -1 ) than the star-shaped Cu 2 O, and also exhibited good cyclability. The star-shaped Cu 2 O particles presented poor cyclability due to pulverization and deterioration after cycling, but the morphology of the cubic Cu 2 O particles was stable even after 50 cycles

Low-pH-induced transformation of bilayer membrane into bicontinuous cubic phase in dioleoylphosphatidylserine/monoolein membranes.

Science.gov (United States)

Okamoto, Yoshihide; Masum, Shah Md; Miyazawa, Haruna; Yamazaki, Masahito

2008-04-01

Cubic biomembranes, nonbilayer membranes with connections in three-dimensional space that have a cubic symmetry, have been observed in various cells. Interconversion between the bilayer liquid-crystalline (L(alpha)) phase and cubic phases attracted much attention in terms of both biological and physicochemical aspects. Herein we report the pH effect on the phase and structure of dioleoylphosphatidylserine (DOPS)/monoolein (MO) membranes under a physiological ion concentration condition, which was revealed by small-angle X-ray scattering (SAXS) measurement. At neutral pH, DOPS/MO membranes containing high concentrations of DOPS were in the L(alpha) phase. First, the pH effect on the phase and structure of the multilamellar vesicles (MLVs) of the DOPS/MO membranes preformed at neutral pH was investigated by adding various low-pH buffers into the MLV suspension. For 20%-DOPS/80%-MO MLVs, at and below pH 2.9, a transition from the L(alpha) to cubic (Q(224)) phase occurred within 1 h. This phase transition was reversible; a subsequent increase in pH to a neutral one in the membrane suspension transformed the cubic phase into the original L(alpha) phase. Second, we found that a decrease in pH transformed large unilamellar vesicles of DOPS/MO membranes into the cubic phase under similar conditions. We have proposed the mechanism of the low-pH-induced phase transition and also made a quantitative analysis on the critical pH of the phase transition. This finding is the first demonstration that a change in pH can induce a reversible phase transition between the L(alpha) and cubic phases of lipid membranes within 1 h.

Measuring light-by-light scattering at the LHC and FCC

CERN Document Server

d'Enterria, David

2016-01-01

Elastic light-by-light scattering, $\\gamma\\gamma\\to\\gamma\\gamma$, can be measured in electromagnetic interactions of lead (Pb) ions at the Large Hadron Collider (LHC) and Future Circular Collider (FCC), using the large (quasi)real photon fluxes available in ultraperipheral collisions. The $\\gamma\\gamma\\to\\gamma\\gamma$ cross sections for diphoton masses m$_{\\gamma\\gamma}>$ 5 GeV in pp, pPb, and PbPb collisions at LHC ($\\sqrt{\\rm s_{_{NN}}}$ = 5.5, 8.8, 14 TeV) and FCC ($\\sqrt{\\rm s_{_{NN}}}$ = 39, 63, 100 TeV) center-of-mass energies are presented. The measurement has controllable backgrounds in PbPb collisions, and one expects about 70 and 2500 signal events per year at the LHC and FCC respectively, after typical detector acceptance and reconstruction efficiency selections.

Nonsymmorphic cubic Dirac point and crossed nodal rings across the ferroelectric phase transition in LiOsO3

Science.gov (United States)

Yu, Wing Chi; Zhou, Xiaoting; Chuang, Feng-Chuan; Yang, Shengyuan A.; Lin, Hsin; Bansil, Arun

2018-05-01

Crystalline symmetries can generate exotic band-crossing features, which can lead to unconventional fermionic excitations with interesting physical properties. We show how a cubic Dirac point—a fourfold-degenerate band-crossing point with cubic dispersion in a plane and a linear dispersion in the third direction—can be stabilized through the presence of a nonsymmorphic glide mirror symmetry in the space group of the crystal. Notably, the cubic Dirac point in our case appears on a threefold axis, even though it has been believed previously that such a point can only appear on a sixfold axis. We show that a cubic Dirac point involving a threefold axis can be realized close to the Fermi level in the nonferroelectric phase of LiOsO3. Upon lowering temperature, LiOsO3 has been shown experimentally to undergo a structural phase transition from the nonferroelectric phase to the ferroelectric phase with spontaneously broken inversion symmetry. Remarkably, we find that the broken symmetry transforms the cubic Dirac point into three mutually crossed nodal rings. There also exist several linear Dirac points in the low-energy band structure of LiOsO3, each of which is transformed into a single nodal ring across the phase transition.

Electrochemical properties and diffusion of a redox active surfactant incorporated in bicontinuous cubic and lamellar phase

International Nuclear Information System (INIS)

Kostela, J.; Elmgren, M.; Almgren, M.

2005-01-01

The objective of this study was to investigate the electrochemical behaviour of the divalent redox active surfactant, N-cetyl-N'-methylviologen (CMV), in bicontinuous cubic and lamellar phases. The liquid crystalline phases were prepared from the system glycerolmonooleate (GMO)-water (and brine)-cationic surfactant. A comparison of the phase behaviour of GMO with the monovalent cetyltrimethylammonium bromide (CTAB) and the divalent CMV surfactant showed that the surfactants gave about the same effect at the same surface charge density. The electrochemical measurements were made with a mixture of CTAB and CMV as the surfactant. Cyclic voltammetry was used to study the electrochemistry of CMV incorporated in the cubic and lamellar phases that were spread on a gold electrode. The E 0 -values in the cubic samples were more negative (-0.55 V versus SCE) than in the lamellar samples (-0.53 V versus SCE). This can be explained by the higher charge density in the lamellar phase. The diffusion coefficients were also measured in the cubic phase. The mass transport is slowed down about fifty times in the cubic phase compared to in the pure electrolyte. The concentration dependence on the diffusion coefficient was also investigated. No electron hopping could be observed, which suggest that diffusional movement of the redox probe is the main source of charge transport. By placing the samples on a conducting glass slide, spectroelectrochemical investigations were performed. In the lamellar phase strong dimerization was detected at high concentration of viologen, but much less in the cubic phase

Electrochemical properties and diffusion of a redox active surfactant incorporated in bicontinuous cubic and lamellar phase

Energy Technology Data Exchange (ETDEWEB)

Kostela, J. [Uppsala University, Department of Physical Chemistry, Box 579, S-75123 Uppsala (Sweden)]. E-mail: johan.kostela@fki.uu.se; Elmgren, M. [Uppsala University, Department of Physical Chemistry, Box 579, S-75123 Uppsala (Sweden); Almgren, M. [Uppsala University, Department of Physical Chemistry, Box 579, S-75123 Uppsala (Sweden)

2005-05-30

The objective of this study was to investigate the electrochemical behaviour of the divalent redox active surfactant, N-cetyl-N'-methylviologen (CMV), in bicontinuous cubic and lamellar phases. The liquid crystalline phases were prepared from the system glycerolmonooleate (GMO)-water (and brine)-cationic surfactant. A comparison of the phase behaviour of GMO with the monovalent cetyltrimethylammonium bromide (CTAB) and the divalent CMV surfactant showed that the surfactants gave about the same effect at the same surface charge density. The electrochemical measurements were made with a mixture of CTAB and CMV as the surfactant. Cyclic voltammetry was used to study the electrochemistry of CMV incorporated in the cubic and lamellar phases that were spread on a gold electrode. The E {sup 0}-values in the cubic samples were more negative (-0.55 V versus SCE) than in the lamellar samples (-0.53 V versus SCE). This can be explained by the higher charge density in the lamellar phase. The diffusion coefficients were also measured in the cubic phase. The mass transport is slowed down about fifty times in the cubic phase compared to in the pure electrolyte. The concentration dependence on the diffusion coefficient was also investigated. No electron hopping could be observed, which suggest that diffusional movement of the redox probe is the main source of charge transport. By placing the samples on a conducting glass slide, spectroelectrochemical investigations were performed. In the lamellar phase strong dimerization was detected at high concentration of viologen, but much less in the cubic phase.

Highly (001) oriented L1{sub 0}-CoPt/TiN multilayer films on glass substrates with perpendicular magnetic anisotropy

Energy Technology Data Exchange (ETDEWEB)

An, Hongyu; Sannomiya, Takumi; Muraishi, Shinji; Nakamura, Yoshio; Shi, Ji, E-mail: shi.j.aa@m.titech.ac.jp [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Xie, Qian; Zhang, Zhengjun [Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Wang, Jian [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan)

2015-03-15

To obtain strong perpendicular magnetic anisotropy (PMA) based on L1{sub 0} structure for magnetic storage devices, costly single crystalline substrates are generally required to achieve (001) texture. Recently, various studies also have focused on depositing different kinds of seed layers on glass or other amorphous substrates to promote (001) preferred orientation of L1{sub 0} CoPt and FePt. TiN is a very promising seed layer material because of its cubic crystalline structure (similar to MgO) and excellent diffusion barring property even at high temperatures. In the present work, highly (001) oriented L1{sub 0}-CoPt/TiN multilayer films have been successfully deposited on glass substrates. After annealing at 700 °C, the film exhibits PMA, and a strong (001) peak is detected from the x-ray diffraction profiles, indicating the ordering transformation of CoPt layers from fcc (A1) to L1{sub 0} structure. It also is found that alternate deposition of cubic TiN and CoPt effectively improves the crystallinity and (001) preferred orientation of CoPt layers. This effect is verified by the substantial enhancement of (001) reflection and PMA with increasing the period number of the multilayer films.

Effect of Rh-based additives on NO and CO formed during regeneration of spent FCC catalyst

Energy Technology Data Exchange (ETDEWEB)

Iliopoulou, E.F.; Efthimiadis, E.A.; Vasalos, I.A. [Aristotle University of Thessaloniki and Center for Research and Technology Hellas, Chemical Process Engineering Research Institute, Department of Chemical Engineering, P.O. Box 1517, 54006 University City, Thessaloniki (Greece); Barth, J.-O.; Lercher, J.A. [Institut fur Technische Chemie, Technische Universitat Munchen, Lichtenbergstrasse 4, D-85748 Garching (Germany)

2004-02-10

Regeneration studies of spent FCC catalyst were performed in a bench-scale unit under reaction conditions that sufficiently simulate those in the regenerator of the fluid catalytic cracking (FCC) unit. The effect of a conventional Pt-based CO promoter (CP-3) on the composition of flue gases was examined. As expected addition of CP-3 in the catalytic inventory decreased CO emissions by one order of magnitude, but tripled the NO emissions independently of the concentration of CO promoter used. Addition of a series of Rh-based catalysts modified the composition of flue gases emitted during regeneration. The parameters under study were the catalytic support, the Rh loading on the additive, and the amount of additive used during regeneration. Both a stoichiometric spinel MgO{center_dot}Al{sub 2}O{sub 3} of high crystallinity and a commercial alumina were competent supports. Promotion of the alumina support with Ce or performing regeneration introducing CO did not affect the additive performance significantly. A combined performance of CO oxidation and NO reduction was achieved minimizing both the Rh loading in the additive (0.1wt.%) and the concentration of additive used during regeneration (1wt.%). IR studies suggest that NO reduction by CO over Rh/alumina additives proceeds via the dissociative adsorption of NO, the formation of NCO species on Rh and their migration to the alumina support to finally yield N{sub 2} and CO{sub 2}.

Vacancy formation enthalpies in bcc and fcc FeCo by positron annihilation

International Nuclear Information System (INIS)

Jackman, J.A.; Kim, S.M.; Buyers, W.J.L.

1982-01-01

A long slit angular correlation apparatus was used to measure the peak coincidence count rate in stoichiometric FeCo from 290 K to 1510 K. The count rate did not change significantly at the order-disorder phase transition (1008 K), but decreased sharply by 3.2% at the bcc-fcc phase transition at 1258 K. The threshold temperatures for the trapping of positrons in vacancies are measured to be 1125 K for the bcc phase and 1260 K for the fcc phase. The vacancy formation enthalpies in the bcc and fcc phases are determined to be 1.45 +- 0.05 eV and 1.63 +- 0.05 eV. The activation energies for self-diffusion have been estimated from the threshold temperatures, and are found to be 2.45 eV and 2.74 eV for the bcc and fcc phases respectively. (Auth.)

Status of the FCC-ee Interaction Region Design

CERN Document Server

Roman Martin; Medina, L

2015-01-01

The FCC-ee project is a high-luminosity circular electron-positron collider envisioned to operate at center-of-mass energies from 90 to 350 GeV, allowing high-precision measurements of the properties of the Z, W and Higgs boson as well as the top quark. It is considered to be a predecessor of a new 100 TeV proton-proton collider hosted in the same 80 to 100 km tunnel in the Geneva area. Currently two interaction region designs are being developed by CERN and BINP using different approaches to the definition of baseline parameters. Both preliminary designs are presentedwith the aimof highlighting the challenges the FCC-ee is facing.

Interdiffusion and atomic mobility studies in Ni-rich fcc Ni−Al−Mn alloys

International Nuclear Information System (INIS)

Cheng, Kaiming; Liu, Dandan; Zhang, Lijun; Du, Yong; Liu, Shuhong; Tang, Chengying

2013-01-01

Highlights: •The interdiffusion coefficients of fcc Ni–Al–Mn alloys are experimentally determined. •The atomic mobilities of fcc Ni–Al–Mn alloys have been assessed. •The calculated results agree well with the present experimental diffusivities. •The mobility parameters obtained can be used to predict many diffusion phenomena. -- Abstract: By employing nine groups of bulk diffusion couples together with electron probe microanalysis technique, the composition dependence of ternary interdiffusion coefficients in Ni-rich fcc Ni−Al−Mn alloys at 1373 K was determined via the Matano–Kirkaldy method. The experimental interdiffusion coefficients were critically assessed to obtain the atomic mobilities of Ni, Al and Mn in fcc Ni−Al−Mn alloys by using the DICTRA (DIffusion-Controlled TRAnsformations) software package. The reliability of these mobilities was validated by comprehensive comparison between the model-predicted diffusion properties and the experimental data. The obtained atomic mobilities could be used to describe various diffusion phenomena in fcc Ni–Al–Mn alloys, such as the concentration profiles, interdiffusion flux and diffusion paths

Ground state searches in fcc intermetallics

International Nuclear Information System (INIS)

Wolverton, C.; de Fontaine, D.; Ceder, G.; Dreysse, H.

1991-12-01

A cluster expansion is used to predict the fcc ground states, i.e., the stable phases at zero Kelvin as a function of composition, for alloy systems. The intermetallic structures are not assumed, but derived regorously by minimizing the configurational energy subject to linear constraints. This ground state search includes pair and multiplet interactions which spatially extend to fourth nearest neighbor. A large number of these concentration-independent interactions are computed by the method of direct configurational averaging using a linearized-muffin-tin orbital Hamiltonian cast into tight binding form (TB-LMTO). The interactions, derived without the use of any adjustable or experimentally obtained parameters, are compared to those calculated via the generalized perturbation method extention of the coherent potential approximation within the context of a KKR Hamiltonian (KKR-CPA-GPM). Agreement with the KKR-CPA-GPM results is quite excellent, as is the comparison of the ground state results with the fcc-based portions of the experimentally-determined phase diagrams under consideration

First-principles calculations of the structural and thermodynamic properties of bcc, fcc and hcp solid solutions in the Al-TM (TM = Ti, Zr and Hf) systems: A comparison of cluster expansion and supercell methods

International Nuclear Information System (INIS)

Ghosh, G.; Walle, A. van de; Asta, M.

2008-01-01

The thermodynamic properties of solid solutions with body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed (hcp) structures in the Al-TM (TM = Ti, Zr and Hf) systems are calculated from first-principles using cluster expansion (CE), Monte-Carlo simulation and supercell methods. The 32-atom special quasirandom structure (SQS) supercells are employed to compute properties at 25, 50 and 75 at.% TM compositions, and 64-atom supercells have been employed to compute properties of alloys in the dilute concentration limit (one solute and 63 solvent atoms). In general, the energy of mixing (Δ m E) calculated by CE and dilute supercells agree very well. In the concentrated region, the Δ m E values calculated by CE and SQS methods also agree well in many cases; however, noteworthy discrepancies are found in some cases, which we argue originate from inherent elastic and dynamic instabilities of the relevant parent lattice structures. The importance of short-range order on the calculated values of Δ m E for hcp Al-Ti alloys is demonstrated. We also present calculated results for the composition dependence of the atomic volumes in random solid solutions with bcc, fcc and hcp structures. The properties of solid solutions reported here may be integrated within the CALPHAD formalism to develop reliable thermodynamic databases in order to facilitate: (i) calculations of stable and metastable phase diagrams of binary and multicomponent systems, (ii) alloy design, and (iii) processing of Al-TM-based alloys

Annealing behaviour of structural and magnetic properties of evaporated Co thin films

International Nuclear Information System (INIS)

Jergel, M; Halahovets, Y; Siffalovic, P; Mat'ko, I; Senderak, R; Majkova, E; Luby, S; Cheshko, I; Protsenko, S

2009-01-01

Cobalt thin films of 50 nm nominal thickness were e-beam evaporated on silicon substrates covered with thermal oxide. Two series of independent and cumulative vacuum annealings up to 600 deg. C and 650 deg. C, respectively, were performed. The x-ray diffraction, specular and non-specular x-ray reflectivity and longitudinal magneto-optical Kerr effect measurements were applied to probe the annealing behaviour of the film structure and magnetic properties. A gradual transition from the hexagonal close-packed (hcp) to the face-centred cubic (fcc) structure was observed. Evolution of the in-plane magnetic anisotropy is dominated by residual stresses which relax during the structural transformation. The coercivity follows the stress behaviour in the hcp phase up to 300 deg. C and increases abruptly above 400 deg. C due to improving the magneto-crystalline anisotropy in the growing fcc crystallites and enhanced surface/interface roughness.

Heat capacities, third-law entropies and thermodynamic functions of the negative thermal expansion materials, cubic α-ZrW2O8 and cubic ZrMo2O8, from T=(0 to 400) K

International Nuclear Information System (INIS)

Stevens, Rebecca; Linford, Jessica; Woodfield, Brian F.; Boerio-Goates, Juliana.; Lind, Cora; Wilkinson, Angus P.; Kowach, Glen

2003-01-01

The molar heat capacities of crystalline cubic α-ZrW 2 O 8 and cubic ZrMo 2 O 8 have been measured at temperatures from (0.6 to 400) K. At T=298.15 K, the standard molar heat capacities are (207.01±0.21) J·K -1 ·mol -1 for the tungstate and (210.06±0.42) J·K -1 ·mol -1 for the molybdate. Thermodynamic functions have been generated from smoothed fits of the experimental results. The standard molar entropies for the tungstate and molybdate are (257.96±0.50) J·K -1 ·mol -1 and (254.3±1) J·K -1 ·mol -1 , respectively. The uncertainty of the entropy of the cubic ZrMo 2 O 8 is larger due to the presence of small chemical and phase impurities whose effects cannot be corrected for at this time. The heat capacities of the negative thermal expansion materials have been compared to the weighted sums of their constituent binary oxides. Both negative thermal expansion materials have heat capacities which are significantly greater than the sum of the binary oxides over the entire temperature region

Pressure Profile in the experimental area of FCC-hh and FCC-ee calculated by an analytical code

CERN Multimedia

Aichinger, Ida

2017-01-01

Ultra high vacuum in the beam pipe is a basic requirement for the Future Circular Colliders (FCC). The dimension of the FCC and the high energy of the particles will make this requirement challenging. Simulations that predict the vacuum quality due to material and beam induced effects will allow to evaluate different designs and to choose an optimal solution. The mathematical model behind the simulations will be shown. Four coupled differential equations describe the mass conservation of the residual gas particles in the beam pipe. The sinks include all kind of distributed and local pumping. The sources are caused by synchrotron radiation, electron clouds, thermal outgassing and ion-induced desorption. The equation system is solved by an analytical method. This requires a transformation to first order equations for which a general valid solution exists. Adding a particular solution and the inclusion of appropriate boundary conditions define the solution function. The big advantage here is that an analytical...

Synthesis of cubic Y zeolite using a pulsed microwave heating system

Directory of Open Access Journals (Sweden)

Araújo L.R.G. de

1999-01-01

Full Text Available Cubic Y zeolite were successfully synthesized using microwave heating for 18 - 25 min, whereas 10 - 50 h are required by hydrothermal heating technique depending upon the lattice Si/Al ratio. To this end, we used a commercial microwave oven modified in order to provide pulsed microwave pumping on the synthesis mixtures. The obtained samples were analyzed by X-ray diffraction, BET surface area and infrared spectroscopy measurements. As a result, we verify that Y zeolite samples obtained from hydrogels containing low aluminum contents, present a good degree of crystallinity and then can be suitable for using in adsorption and catalysis experiments.

Towards a Monochromatization Scheme for Direct Higgs Production at FCC-ee

CERN Document Server

Valdivia Garcia, Marco Alan; Zimmermann, Frank

2016-01-01

Direct Higgs production in e+e− collisions at the FCC is of interest if the centre-of-mass energy spread can be reduced by at least an order of magnitude. A monochromatization scheme, to accomplish this, can be realized with horizontal dispersion of opposite sign for the two colliding beams at the interaction point (IP). We recall historical approaches to monochromatization, then derive a set of IP parameters which would provide the required performance in FCC e+e− collisions at 62.5 GeV beam energy, compare these with the baseline optics parameters at neighbouring energies (45.6 and 80 GeV), comment on the effect of beamstrahlung, and indicate the modifications of the FCC-ee final-focus optics needed to obtain the required parameters.

Diffusivities and atomic mobilities in disordered fcc and ordered L12 Ni–Al–W alloys

International Nuclear Information System (INIS)

Chen, Chong; Zhang, Lijun; Xin, Jinghua; Wang, Yaru; Du, Yong; Luo, Fenghua; Zhang, Zhongjian; Xu, Tao; Long, Jianzhan

2015-01-01

Highlights: • The atomic mobilities for fcc Al–W, fcc Ni–W, fcc Ni–Al–W and L1 2 Ni–Al–W alloys were critically assessed. • The impurity diffusivity of W in fcc-Al was obtained via first-principles calculations. • The calculated results agree well with the diffusivities available in the literature. • Two fcc/L1 2 -type diffusion couples were prepared and the concentration-distance profiles were measured. • The model-predicted concentration profiles agree well with the experimental data in the literature and in the present work. - Abstract: Based on various experimentally measured diffusivities available in the literature together with the reported thermodynamic parameters, the atomic mobilities for disordered fcc and ordered L1 2 Ni–Al–W alloys were assessed on the basis of a recently developed phenomenological model incorporated in the DICTRA software. In order to provide the missing impurity diffusion coefficients of W in fcc-Al, first-principles calculations were utilized in the present work. Comprehensive comparisons between the calculated and experimental diffusion coefficients show that all the experimental data can be well reproduced by the atomic mobilities obtained in the present work. In order to further verify the reliability of the presently obtained atomic mobilities, two fcc/L1 2 -type diffusion couples (i.e., Ni–5 at.% Al–5 at.% W/Ni–20 at.% Al–4 at.% W and Ni/Ni–22 at.% Al–2 at.% W) were prepared and the concentration-distance profiles after annealing at 1323 K for 86.4 ks were measured. The excellent agreement between the model-predicted concentration-distance profiles and the experimental data indicates that the presently obtained atomic mobilities in fcc/L1 2 Ni–Al–W alloys are reliable

Quality by Design approach to spray drying processing of crystalline nanosuspensions.

Science.gov (United States)

Kumar, Sumit; Gokhale, Rajeev; Burgess, Diane J

2014-04-10

Quality by Design (QbD) principles were explored to understand spray drying process for the conversion of liquid nanosuspensions into solid nano-crystalline dry powders using indomethacin as a model drug. The effects of critical process variables: inlet temperature, flow and aspiration rates on critical quality attributes (CQAs): particle size, moisture content, percent yield and crystallinity were investigated employing a full factorial design. A central cubic design was employed to generate the response surface for particle size and percent yield. Multiple linear regression analysis and ANOVA were employed to identify and estimate the effect of critical parameters, establish their relationship with CQAs, create design space and model the spray drying process. Inlet temperature was identified as the only significant factor (p value dried nano-crystalline powders. Aspiration and flow rates were identified as significant factors affecting yield (p value dried at higher inlet temperatures had lower moisture compared to those dried at lower inlet temperatures. Published by Elsevier B.V.

Face centered cubic SnSe as a Z2 trivial Dirac nodal line material

OpenAIRE

Tateishi, Ikuma; Matsuura, Hiroyasu

2018-01-01

The presence of Dirac nodal line in the time-reversal and inversion symmetric system is dictated by Z2 index when spin-orbit interaction is absent. With the first principles calculation, we show that the Dirac nodal line can emerge in Z2 trivial material by calculating the band structure of SnSe of face centered cubic lattice as an example and it becomes a topological crystalline insulator when spin-orbit interaction is taken into account. We clarify the origin of the Dirac nodal line by obta...

Chaotic Fluid Mixing in Crystalline Sphere Arrays

Science.gov (United States)

Turuban, R.; Lester, D. R.; Le Borgne, T.; Méheust, Y.

2017-12-01

We study the Lagrangian dynamics of steady 3D Stokes flow over simple cubic (SC) and body-centered cubic (BCC) lattices of close-packed spheres, and uncover the mechanisms governing chaotic mixing. Due to the cusp-shaped sphere contacts, the topology of the skin friction field is fundamentally different to that of continuous (non-granular) media (e.g. open pore networks), with significant implications for fluid mixing. Weak symmetry breaking of the flow orientation with respect to the lattice symmetries imparts a transition from regular to strong chaotic mixing in the BCC lattice, whereas the SC lattice only exhibits weak mixing. Whilst the SC and BCC lattices share the same symmetry point group, these differences are explained in terms of their space groups, and we find that a glide symmetry of the BCC lattice generates chaotic mixing. These insight are used to develop accurate predictions of the Lyapunov exponent distribution over the parameter space of mean flow orientation, and point to a general theory of mixing and dispersion based upon the inherent symmetries of arbitrary crystalline structures.

Attrition Resistant Fischer-Tropsch Catalysts Based on FCC Supports

Energy Technology Data Exchange (ETDEWEB)

Adeyiga, Adeyinka

2010-02-05

Commercial spent fluid catalytic cracking (FCC) catalysts provided by Engelhard and Albemarle were used as supports for Fe-based catalysts with the goal of improving the attrition resistance of typical F-T catalysts. Catalysts with the Ruhrchemie composition (100 Fe/5 Cu/4.2 K/25 spent FCC on mass basis) were prepared by wet impregnation. XRD and XANES analysis showed the presence of Fe{sub 2}O{sub 3} in calcined catalysts. FeC{sub x} and Fe{sub 3}O{sub 4} were present in the activated catalysts. The metal composition of the catalysts was analyzed by ICP-MS. F-T activity of the catalysts activated in situ in CO at the same conditions as used prior to the attrition tests was measured using a fixed bed reactor at T = 573 K, P = 1.38 MPa and H{sub 2}:CO ratio of 0.67. Cu and K promoted Fe supported over Engelhard provided spent FCC catalyst shows relatively good attrition resistance (8.2 wt% fines lost), high CO conversion (81%) and C{sub 5}+ hydrocarbons selectivity (18.3%).

The effect of relativity on stability of Copernicium phases, their electronic structure and mechanical properties

Science.gov (United States)

Čenčariková, Hana; Legut, Dominik

2018-05-01

The phase stability of the various crystalline structures of the super-heavy element Copernicium was determined based on the first-principles calculations with different levels of the relativistic effects. We utilized the Darwin term, mass-velocity, and spin-orbit interaction with the single electron framework of the density functional theory while treating the exchange and correlation effects using local density approximations. It is found that the spin-orbit coupling is the key component to stabilize the body-centered cubic (bcc) structure over the hexagonal closed packed (hcp) structure, which is in accord with Sol. Stat. Comm. 152 (2012) 530, but in contrast to Atta-Fynn and Ray (2015) [11], Gaston et al. (2007) [10], Papaconstantopoulos (2015) [9]. It seems that the main role here is the correct description of the semi-core relativistic 6p1/2 orbitals. The all other investigated structures, i.e. face-centered cubic (fcc) , simple cubic (sc) as well as rhombohedral (rh) structures are higher in energy. The criteria of mechanical stability were investigated based on the calculated elastic constants, identifying the phase instability of fcc and rh structures, but surprisingly confirm the stability of the energetically higher sc structure. In addition, the pressure-induced structural transition between two stable sc and bcc phases has been detected. The ground-state bcc structure exhibits the highest elastic anisotropy from single elements of the Periodic table. At last, we support the experimental findings that Copernicium is a metal.

Growth and characterization of β-In N films on Mg O: the key role of a β-Ga N buffer layer in growing cubic In N

International Nuclear Information System (INIS)

Navarro C, H.; Perez C, M.; Rodriguez, A. G.; Lopez L, E.; Vidal, M. A.

2012-01-01

Cubic In N samples were grown on Mg O (001) substrates by gas source molecular beam epitaxy. In general, we find that In N directly deposited onto the Mg O substrate results in polycrystalline or columnar films of hexagonal symmetry. We find that adequate conditions to grow the cubic phase of this compound require the growth of an initial cubic Ga N buffer interlayer (β-t Ga N) on the Mg O surface. Subsequently, the growth conditions were optimized to obtain good photoluminescence (Pl) emission. The resultant In N growth is mostly cubic, with very small hexagonal inclusions, as confirmed by X-ray diffraction and scanning electron microscopy studies. Good crystalline quality requires that the samples to be grown under rich Indium metal flux. The cubic β-t In N/Ga N/Mg O samples exhibit a high signal to noise ratio for Pl at low temperatures (20 K). The Pl is centered at O.75 eV and persist at room temperature. (Author)

Magnetic properties of metastable bcc and fcc Fe-Cu alloys produced by vapor quenching

International Nuclear Information System (INIS)

Sumiyama, Kenji; Yoshitake, Tsutomu; Nakamura, Yoji

1984-01-01

High concentration Fesub(1-x)Cusub(x) alloys have been obtained by rf sputtering technique and investigated by X-ray diffraction and magnetization measurements. The bcc phase is extended over the region with x=0-0.4, while the fcc phase with x=0.6-1.0. For x=0.4-0.6, we have the mixed phase of bcc and fcc. The lattice constant of bcc phase increases slightly and that of fcc phase decreases with increasing x. In the bcc alloys, the average magnetic moment decreases with increasing x and deviates upwards from the simple dilution law. In the fcc alloys, the magnetic moment also decreases with increasing x but it deviates downwards from the simple dilution law. The Curie temperature, Tsub(c), of the Fesub(1-x)Cusub(x) alloys decreases abruptly with increasing x: Tsub(c) is higher than 750 K for the bcc alloys, while it is lower than 320 K for the fcc alloys and become 0 K at about x=0.92. (author)

Magnetic properties of fcc (Co95Fe5)1-xAlx ribbons

International Nuclear Information System (INIS)

Makhlouf, Salah A.; Parker, F.T.; Benameur, T.

1999-01-01

Rapidly quenched (Co 95 Fe 5 ) 1-x Al x ribbons are investigated by X-ray diffraction, magnetization, and Moessbauer effect measurements. A single fcc phase is obtained for all ribbons x ≤ 10 at.%. The lattice constant increases linearly with x and is discussed in connection with magnetic moment. The influence of Al substitution on both magnetization and Fe-atom hyperfine field (H) is studied. At 296 K, the magnetization decreases linearly while H drops nonlinearly as x increases. Al substitution leads to substantial differences in iron hyperfine fields in bcc and fcc systems. Fe moment is perturbed differently by Al substitution in fcc (Co 95 Fe 5 ) 1-x Al x and bcc Fe-Al systems

Considerations on operation schedule and maintenance aspects of FCC-hh

CERN Document Server

Niemi, Arto; Foraz, Katy

2018-01-01

The Future Circular Hadron Collider (FCC-hh) has ambitious goals for integrated luminosity production. Reaching these goals requires reducing the time for planned technical stops and commissioning, compared to the LHC. This note describes potential options for an FCC-hh operation schedule. Special attention is given to considerations on how to accomplish the required maintenance activities in a limited time frame. The note recommends to study further the feasibility and cost-efficiency of operating without annual stops and longer intervals between long shutdowns.

Nucleation of dislocation loops during irradiation in binary FCC alloys with different alloy compositions

International Nuclear Information System (INIS)

Hashimoto, T.; Shigenaka, N.; Fuse, M.

1992-01-01

Dislocation loop nucleation is analyzed using a rate theory based model for face-centered cubic (fcc) binary alloys containing A- and B-atoms. In order to calculate the nucleation process in concentrated alloys, the model considers three types of interstitial dumbbells composed of A- and B-atoms, AA-, BB-, and AB-type dumbbells. Conversions between these interstitial dumbbells are newly introduced in the formulation in consideration of dumbbell configurations and movements. The model also includes reactions, such as point defect production by irradiation, mutual recombination of an interstitial and a vacancy, and dislocation loop nucleation and growth. Parameter values are chosen based on the atom size of the alloy component elements, and dislocation loop nucleation kinetics are investigated while varying alloy compositions. Two different types of kinetics are obtained in accordance with the dominant loop nucleus type. The migration energy difference of AA- and BB-type interstitial dumbbells is important in the determination of the dominant loop nucleus type. The present model predicts that the dislocation loop concentration decrease with increasing under sized atoms content, but defect production rate and temperature dependences of loop concentration are insensitive to alloy compositions. (author)

Reusing a residue of the oil industry (FCC) in the production of building elements

OpenAIRE

Caicedo Casso, Eduard Andrés; Universidad del Valle; Mejía de Gutiérrez, Ruby; Universidad del Valle; Gordillo Suárez, Marisol; Universidad Autónoma de Occidente; Torres Agredo, Janneth; Universidad Nacional de Colombia, sede Palmira

2015-01-01

This paper analyzes the feasibility of using a residue of spent catalyst (FCC) of the cracking process, from a Colombian oil company, in the production of building elements such as locks and pavers. To define the optimal mix of portland cement/FCC, Portland cement mortars with FCC ratios between 0 and 70% as replacement of cement were prepared and its compressive strength is evaluated at ages up to 28 days of curing. Using a statistical processing, applying the methodology of response, the pr...

Quasi-Dual-Packed-Kerneled Au49 (2,4-DMBT)27 Nanoclusters and the Influence of Kernel Packing on the Electrochemical Gap.

Science.gov (United States)

Liao, Lingwen; Zhuang, Shengli; Wang, Pu; Xu, Yanan; Yan, Nan; Dong, Hongwei; Wang, Chengming; Zhao, Yan; Xia, Nan; Li, Jin; Deng, Haiteng; Pei, Yong; Tian, Shi-Kai; Wu, Zhikun

2017-10-02

Although face-centered cubic (fcc), body-centered cubic (bcc), hexagonal close-packed (hcp), and other structured gold nanoclusters have been reported, it was unclear whether gold nanoclusters with mix-packed (fcc and non-fcc) kernels exist, and the correlation between kernel packing and the properties of gold nanoclusters is unknown. A Au 49 (2,4-DMBT) 27 nanocluster with a shell electron count of 22 has now been been synthesized and structurally resolved by single-crystal X-ray crystallography, which revealed that Au 49 (2,4-DMBT) 27 contains a unique Au 34 kernel consisting of one quasi-fcc-structured Au 21 and one non-fcc-structured Au 13 unit (where 2,4-DMBTH=2,4-dimethylbenzenethiol). Further experiments revealed that the kernel packing greatly influences the electrochemical gap (EG) and the fcc structure has a larger EG than the investigated non-fcc structure. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Positron lifetime studies of the hcp to fcc transformation induced by mechanical attrition of elemental titanium

International Nuclear Information System (INIS)

Manna, I.; Chattopadhyay, P.P.; Nandi, P.; Nambissan, P.M.G.

2004-01-01

Nanocrystallisation by planetary ball-milling of high purity elemental titanium (Ti) revealed a polymorphic transformation from its normal hexagonal close packed (hcp) structure to a face-centered cubic (fcc) phase. Positron lifetime measurements were carried out on samples collected after different hours of milling to characterize the defect structures at grain surfaces. With increasing hours of milling, the nanocrystalline grain size decreased and the positron lifetimes--one related to the annihilation at the grain surfaces and the other to that at the intergranular open volume domains--increased significantly due to the increased free volume at the trapping vacancy sites. However, between 5 to 10 hours of milling, the two lifetimes decreased before resuming increasing once again. This marked deviation from an otherwise expected continuous increase of positron lifetime coincided with structural rearrangement within the system bringing in an enhancement in the density of electrons. The repacking of atoms along the [0001] crystallographic direction could be a possibility for this observation. Positron radiation effects on the migration and agglomeration of nanoparticles are also discussed

Interdiffusion coefficients and atomic mobilities in fcc Cu-Fe-Mn alloys

Directory of Open Access Journals (Sweden)

Li J.

2014-01-01

Full Text Available In the present work, the interdiffusion coefficients in fcc Cu-Fe-Mn alloys were experimentally determined via a combination of solid/solid diffusion couples, electron probe microanalysis (EPMA technique and Matano-Kirkaldy method. Based on the reliable thermodynamic description of fcc phase in the Cu-Fe-Mn system available in the literature as well as the ternary diffusion coefficients measured in the present work, the atomic mobilities in fcc Cu-Fe-Mn alloys were assessed by utilizing the DICTRA (Diffusion Controlled TRAnsformation software package. The calculated interdiffusion coefficients based on the assessed atomic mobilities agree well with most of the experimental data. The comprehensive comparison between various model-predicted diffusion properties and the measured data, including the concentration penetration profiles, interdiffusion flux profile, and diffusion paths, further verify the reliability of the presently obtained atomic mobilities.

Elastic-constant systematics in f.c.c. metals, including lanthanides-actinides

Energy Technology Data Exchange (ETDEWEB)

Ledbetter, Hassel [Mechanical Engineering Department, University of Colorado, Boulder, Colorado 80309 (United States); Migliori, Albert [Los Alamos National Laboratory (E536), Los Alamos, New Mexico 87545 (United States)

2008-01-15

For f.c.c. metals, using Blackman's diagram of dimensionless elastic-constant ratios, we consider the systematics of physical properties and interatomic bonding. We focus especially on the lanthanides-actinides La, Ce, Yb, Th, U, Pu, those for which we know some monocrystal elastic constants. Their behavior differs from the other f.c.c. metals, and all except La show a negative Cauchy pressure, contrary to most f.c.c. metals, which show a positive Cauchy pressure. Among the lanthanides-actinides, {delta}-Pu stands apart, consistent with its many odd physical properties. Based on elastic-constant correlations, we suggest that {delta}-Pu possesses a strong s-electron interatomic-bonding component together with a covalent component. Elastically, {delta}-Pu shows properties similar to Yb. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Optical properties of crystalline semiconductors and dielectrics

International Nuclear Information System (INIS)

Forouhi, A.R.; Bloomer, I.

1988-01-01

A new formulation for the complex index of refraction, N(E) = n(E)-ik(E), as a function of photon energy E, for crystalline semiconductors and dielectrics is developed based on our previous derivation of N(E) for amorphous materials. The extinction coefficient k(E) is deduced from a one-electron model with finite lifetime for the excited electron state. The refractive index n(E) is then derived from the Kramers-Kronig relation as the Hilbert transform of k(E). It is shown that n(∞)>1. Excellent agreement is found between our equations for n(E) and k(E) and published measured values for crystalline Si, Ge, GaP, GaAs, GaSb, InP, InAs, InSb, SiC, cubic C, and α-SiO 2 , over a wide range of energies (∼0--20 eV). Far fewer parameters, all of which have physical significance, are required and they can be determined for a particular material from the position and strength of the peaks in the k spectrum

Analytic nearest neighbour model for FCC metals

International Nuclear Information System (INIS)

Idiodi, J.O.A.; Garba, E.J.D.; Akinlade, O.

1991-06-01

A recently proposed analytic nearest-neighbour model for fcc metals is criticised and two alternative nearest-neighbour models derived from the separable potential method (SPM) are recommended. Results for copper and aluminium illustrate the utility of the recommended models. (author). 20 refs, 5 tabs

Nonionic diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains: thermotropic and lyotropic liquid crystalline phase behaviour

Energy Technology Data Exchange (ETDEWEB)

Sagnella, Sharon M.; Conn, Charlotte E.; Krodkiewska, Irena; Drummond, Calum J. (CSIRO/MSE)

2014-09-24

The thermotropic and lyotropic liquid crystalline phase behaviour of a series of diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains (geranoyl, H-farnesoyl, and phytanoyl) has been investigated. When neat, both H-farnesoyl and phytanoyl diethanolamide form a smectic liquid crystalline structure at sub-zero temperatures. In addition, all three diethanolamides exhibit a glass transition temperature at around -73 C. Geranoyl diethanolamide forms a lamellar crystalline phase with a lattice parameter of 17.4 {angstrom} following long term storage accompanied by the loss of the glass transition. In the presence of water, H-farnesoyl and phytanoyl diethanolamide form lyotropic liquid crystalline phases, whilst geranoyl diethanolamide forms an L{sub 2} phase. H-farnesoyl diethanolamide forms a fluid lamellar phase (L{sub {alpha}}) at room temperature and up to {approx} 40 C. Phytanoyl diethanolamide displays a rich mesomorphism forming the inverse diamond (Q{sub II}{sup D}) and gyroid (Q{sub II}{sup G}) bicontinuous cubic phases in addition to an L{sub {alpha}} phase.

Energy barrier of bcc-fcc phase transition via the Bain path in Yukawa system

Science.gov (United States)

Kiyokawa, Shuji

2018-05-01

In the Yukawa system with the dimensionless screening parameter κ>1.5 , when bcc-fcc transition occurs via Bain path, we show that spontaneous transitions do not occur even if the system temperature reaches the transition point of bcc-fcc because it is necessary to increase once the free energy in the process of transition from bcc to fcc through Bain deformation. Here, we refer the temporary increment of the free energy during Bain deformation as Bain barrier. Since there are the Bain barriers at the transitions between bcc and fcc phases, these phases may coexist as metastable state in the wide region (not a coexistence line) of κ and the coupling constant Γ. We study the excess energy of the system and the free energy difference between bcc and fcc phases by the Monte Carlo method, where the simulation box is divided into a large number of elements with small volume and a particle in the box is restricted be placed in one of these elements. By this method, we can tabulate the values of the interparticle potential and can calculate the internal energy fast and precisely.

Effects of Ni content on nanocrystalline Fe–Co–Ni ternary alloys synthesized by a chemical reduction method

Energy Technology Data Exchange (ETDEWEB)

Chokprasombat, Komkrich, E-mail: komkrich28@gmail.com [Department of Physics, Faculty of Science, Thaksin University, Phatthalung 93210 Thailand (Thailand); Pinitsoontorn, Supree [Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 Thailand (Thailand); Maensiri, Santi [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 Thailand (Thailand)

2016-05-01

Magnetic properties of Fe–Co–Ni ternary alloys could be altered by changing of the particle size, elemental compositions, and crystalline structures. In this work, Fe{sub 50}Co{sub 50−x}Ni{sub x} nanoparticles (x=10, 20, 40, and 50) were prepared by the novel chemical reduction process. Hydrazine monohydrate was used as a reducing agent under the concentrated basic condition with the presence of poly(vinylpyrrolidone). We found that the nanoparticles were composed of Fe, Co and Ni with compositions according to the molar ratio of the metal sources. Interestingly, the particles were well-crystalline at the as-prepared state without post-annealing at high temperature. Increasing Ni content resulted in phase transformation from body centered cubic (bcc) to face centered cubic (fcc). For the fcc phase, the average particle size decreased when increased the Ni content; the Fe{sub 50}Ni{sub 50} nanoparticles had the smallest average size with the narrowest size distribution. In additions, the particles exhibited ferromagnetic properties at room temperature with the coercivities higher than 300 Oe, and the saturation magnetiation decreased with increasing Ni content. These results suggest that the structural and magnetic properties of Fe–Co–Ni alloys could be adjusted by varying the Ni content. - Highlights: • We prepared nanocrystalline Fe–Co–Ni alloys by a novel chemical reduction process. • Elemental compositions could be well controlled by the molar ratio of metal sources. • Particle size and magnetic properties clearly depended on the Ni contents. • Fe{sub 50}Co{sub 10}Ni{sub 40} exhibited high saturation magnetization of 126.3 emu/g.

Activated states for cross-slip at screw dislocation intersections in face-centered cubic nickel and copper via atomistic simulation

International Nuclear Information System (INIS)

Rao, S.I.; Dimiduk, D.M.; El-Awady, J.A.; Parthasarathy, T.A.; Uchic, M.D.; Woodward, C.

2010-01-01

We extend our recent simulation studies where a screw dislocation in face-centered cubic (fcc) Ni was found to spontaneously attain a low energy partially cross-slipped configuration upon intersecting a forest dislocation. Using atomistic (molecular statics) simulations with embedded atom potentials, we evaluated the activation barrier for a dislocation to transform from fully residing on the glide plane to fully residing on a cross-slip plane intersecting a forest dislocation in both Ni and Cu. The activation energies were obtained by determining equilibrium configurations (energies) when variable pure tensile or compressive stresses were applied along the [1 1 1] direction on the partially cross-slipped state. We show that the activation energy is a factor of 2-5 lower than that for cross-slip in isolation via the Escaig process. The cross-slip activation energies obtained at the intersection in Cu were in reasonable accord with the experimentally determined cross-slip activation energy for Cu. Further, the activation barrier for cross-slip at these intersections was shown to be linearly proportional to (d/b)[ln(√(3)d/b)] 1/2 , as in the Escaig process, where d is the Shockley partial dislocation spacing and b is the Burgers vector of the screw dislocation. These results suggest that cross-slip should be preferentially observed at selected screw dislocation intersections in fcc materials.

Cross-twinning model of fcc crystal growth

NARCIS (Netherlands)

van de Waal, B.W.

1995-01-01

The theory developed in 1960 by Wagner, Hamilton and Seidensticker (WHS-theory) to explain observed crystal growth phenomena in Ge is critically reviewed and shown to be capable of explaining preservation of ABC stacking order in two dimensions in fcc crystals of effectively spherical closed shell

Cellular Phone Towers, FCC registered communications towers. Points were generated from FCC data latlong. Originally created as a basis of comparison for Appraiser's cell tower points, bu comparison was inconclusive. Represented all registered FCC sites as of 6/26/2003. No, Published in 2003, 1:1200 (1in=100ft) scale, Sedgwick County Government.

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Cellular Phone Towers dataset current as of 2003. FCC registered communications towers. Points were generated from FCC data latlong. Originally created as a basis of...

Diffusion behavior and atomic mobilities for fcc Cu–Cr–Ni alloys

International Nuclear Information System (INIS)

Xu, Gaochi; Liu, Yajun; Lei, Fuyue; Sheng, Guang; Kang, Zhitao

2015-01-01

In this work, diffusion couples of fcc Cu–Cr–Ni alloys annealed at 1373 K for 80 h are investigated. The interdiffusion coefficients are retrieved from common compositions of two diffusion couples, which are then combined with thermodynamic descriptions to explore atomic mobilities of Cu, Cr and Ni in fcc Cu–Cr–Ni alloys within the CALPHAD framework. In order to confirm the quality of such kinetic characteristics, a comparison between calculated and experimentally measured concentration profiles of diffusion couples and diffusion paths in Gibbs triangle is made, where the agreement is excellent. The results of this study contribute to the establishment of a general Ni-based mobility database for alloy design. - Highlights: • Atomic mobilities of fcc Cu–Cr–Ni phases were determined. • Experimental interdiffusivities were critically evaluated. • Main and cross interdiffusivities show their peculiarities. • The profiles reveal kinetic importance for alloy microstructures

Effect of annealing temperature on the crystalline quality and phase transformation of chemically deposited CdSe films

International Nuclear Information System (INIS)

Zapata-Torres, M.; Chale-Lara, F.; Caballero-Briones, F.; Calzadilla, O.

2005-01-01

Polycrystalline CdSe thin films were grown on glass substrates by chemical bath deposition at 50 C. The samples were annealed in air atmosphere at different temperatures and characterized by X-ray diffraction and Raman spectroscopy. It was found that the as-grown films have cubic structure. These samples maintain their cubic structure for annealing temperatures between 60 C and 300 C. For annealing temperatures higher than 300 C we obtain a mixture of cubic and hexagonal phases. The analysis made by X-ray diffraction and Raman dispersion show that the samples annealed at temperatures under the phase-transition temperature increase their crystalline quality. In order to determinate the temperature for the complete transition of the cubic phase, we used the precipitated material obtained during the grown of the CdSe films. This material was annealed on air atmosphere between 300 C and 500 C with 50 intervals. The samples were measured by X-ray diffraction. The samples maintained the cubic structure if the annealing temperature is under 300 C. For temperatures between 300 C and 450 C we found a mixture of cubic and hexagonal phase. For an annealing temperature of 500 C we obtain only the hexagonal phase. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

submitter Prospects of Sterile Neutrino Search with the FCC-ee

CERN Document Server

Bay Nielsen, Sissel

A proposed future circular e + e − collider, the FCC-ee, is suggested to search for sterile neutrinos. The Neutrino Minimal Standard Model, νMSM, is a model of sterile neutrinos, that accommodates explanations for several phenomena of physics beyond the Standard Model. This thesis presents an overview of the theoretical motivation for νMSM, an outline of the experimental conditions at the FCC-ee, and a review of previous accelerator bounds for sterile neutrinos. Two studies of sterile neutrinos with masses at the electroweak scale are introduced, an analysis of long lived sterile neutrinos, and an analysis of short lived sterile neutrinos. Both analyses include background studies and sensitivity estimates for the FCC-ee detector. The study of long lived sterile neutrinos is based on a search for detectable displaced vertices with 1012 Z decays, obtaining a search reach on the mixing angle |θ| 2 as small as 10−11. The study of short lived sterile neutrinos is a Monte Carlo study with a cut-based analysi...

submitter Some Critical Collective Effects for the FCC-ee Collider

CERN Document Server

Belli, Eleonora; Migliorati, Mauro; Persichelli, Serena; Rumolo, Giovanni; Spataro, Bruno; Zobov, Mikhail

2017-01-01

In the framework of the Future Circular Collider (FCC) design studies at CERN [1], the high luminosity electron-positron collider FCC-ee is considered as a possible first step towards FCC-hh, a 100 TeV hadron collider in the same tunnel of about 100 km. Table 1 summarizes the main beam parameters at four different center-of-mass energies from 45.6 GeV (Z pole) to 175 GeV (top pair threshold). One of the major issues for such a kind of machine is represented by collective effects due to electromagnetic fields generated by the interaction of the beam with the vacuum chamber, which could produce instabilities, thus limiting the machine operation and performance. An impedance model is needed to study these instabilities, to predict their effects on the beam dynamics and to find a possible solution for their mitigation. Another critical aspect for the future lepton collider is represented by the electron cloud which will be discussed in the last section of this contribution, together with possible strategies to su...

Exploring the $Z' \\rightarrow t\\overline{t}$ heavy resonance at FCC-hh

CERN Document Server

Smith, Rachel Emma Clarke

2017-01-01

My summer student project explored the feasibility of detecting final states with boosted top quarks at 100 TeV with the baseline FCC-hh detector. I focused specifically on the $Z' \\rightarrow t\\overline{t}$ hadronic process. I determined the exclusion cross-section of $Z' \\rightarrow t\\overline{t}$ and the integrated luminosity required to make a discovery at the baseline FCC detector at 95% confidence level.

Quantitative analysis of thermal diffuse X-ray scattering on single crystals. Communication 2. FCC metals

International Nuclear Information System (INIS)

Najsh, V.E.; Novoselova, T.V.; Sagaradze, I.V.; Kvyatkovskij, B.E.; Fedorov, V.I.; Chernenkov, Yu.P.

1994-01-01

With the use of X-ray diffractometer a study was made into the intensity of diffuse scattering in Ni crystals with FCC lattice. Earlier accomplished quantitative analysis for BCC crystals was extended to FCC lattices. Comparative evaluation was made for cooperative thermal oscillation patterns and corresponding diffuse scattering in crystals of various structures. Measurements on FCC crystals were carried out at room temperature using AgK a lpha-radiation in 96 points of Ni crystal. 8 refs., 4 figs

Chaotic Fluid Mixing in Crystalline Sphere Arrays

Science.gov (United States)

Turuban, Regis; Lester, Daniel; Meheust, Yves; Le Borgne, Tanguy

2017-11-01

We study the Lagrangian dynamics of steady 3D Stokes flow over simple cubic (SC) and body-centered cubic (BCC) lattices of close-packed spheres, and uncover the mechanisms governing chaotic mixing. Due to the cusp-shaped sphere contacts, the topology of the skin friction field is fundamentally different to that of continuous (non-granular) media (e.g. open pore networks), with significant implications for fluid mixing. Weak symmetry breaking of the flow orientation with respect to the lattice symmetries imparts a transition from regular to strong chaotic mixing in the BCC lattice, whereas the SC lattice only exhibits weak mixing. Whilst the SC and BCC lattices share the same symmetry point group, these differences are explained in terms of their space groups, and we find that a glide symmetry of the BCC lattice generates chaotic mixing. These insights are used to develop accurate predictions of the Lyapunov exponent distribution over the parameter space of mean flow orientation, and point to a general theory of mixing and dispersion based upon the inherent symmetries of arbitrary crystalline structures. The authors acknowledge the support of ERC project ReactiveFronts (648377).

Cubic metaplectic forms and theta functions

CERN Document Server

Proskurin, Nikolai

1998-01-01

The book is an introduction to the theory of cubic metaplectic forms on the 3-dimensional hyperbolic space and the author's research on cubic metaplectic forms on special linear and symplectic groups of rank 2. The topics include: Kubota and Bass-Milnor-Serre homomorphisms, cubic metaplectic Eisenstein series, cubic theta functions, Whittaker functions. A special method is developed and applied to find Fourier coefficients of the Eisenstein series and cubic theta functions. The book is intended for readers, with beginning graduate-level background, interested in further research in the theory of metaplectic forms and in possible applications.

Liquid crystalline systems containing Vitamin E TPGS for the controlled transdermal nicotine delivery

Directory of Open Access Journals (Sweden)

Lívia Neves Borgheti-Cardoso

Full Text Available ABSTRACT Transdermal nicotine patches have been used in smoking cessation therapy, suggested for the treatment of skin disorders with eosinophilic infiltration and have been found to improve attention performance in patients with Alzheimer's disease and age-associated memory impairment. However, skin irritation with extended patch use is still a problem. The aim of this work was to develop a simple to prepare liquid crystalline system containing vitamin E TPGS that would be able to control nicotine delivery and reduce irritation and sensitization problems. The liquid crystalline phases were macroscopically characterized by visual analysis and examined microscopically under a polarized light microscope. Topical and transdermal delivery of nicotine were investigated in vitro using porcine ear skin mounted on a Franz diffusion cell. Nicotine skin permeation from the developed cubic phase followed zero-order kinetics (r = 0.993 and was significantly enhanced after 12 h when compared to the control formulation (nicotine solution (p < 0.05 (138.86 ± 20.44 and 64.91 ± 4.06 μg/cm2, respectively. Cubic phase was also able to target viable skin layers in comparison to control solution (8.18 ± 1.89 and 2.63 ± 2.51 μg/cm2, respectively. Further studies to evaluate skin sensitization and irritation are now necessary.

Photonic bandgap structure of 3-D fcc silica nanospheres

Energy Technology Data Exchange (ETDEWEB)

Woo, Y. K.; Ha, N. Y.; Hwang, Ji Soo; Chang, H. J.; Wu, J. W. [Dept. of Physics, Ewha Womans University, Seoul (Korea, Republic of)

2002-07-01

Photonic crystal is an artificial optical material with a periodic dielectric potential, hence exhibiting a bandgap for a propagating electromagnetic wave. We fabricated crystal possessing 3-D fcc opal structure from silica nanospheres. The crystals are self-assembled on a flat glass by evaporating the solvent in the nanosphere suspension at the room temperature. The suspension consists of silica nanospheres with a diameter of 200 nm. The microscopic arrangement of nanospheres is identified by a scanning electron microscope, the resulting structure being fcc.Transmission spectrum of the fabricated photonic crystal in the visible and near-infrared regions is measured at different incident angles to find the distinct Bragg peaks, analysis of which further confirmed the fcc structure of the photonic crystal. From the optical microscopic image, we find that the opal domain varies from 30 μm to 125 μm in size. In order to relate the observed Bragg peaks with the microscopic arrangement of silica nanospheres, we introduced the scalar wave approximation, where the electric field in the medium is treated as a scalar rather than a vector quantity. It is found that the theoretical prediction of the position of bandgap is in a good agreement with the experimental measurement.

Photonic bandgap structure of 3-D fcc silica nanospheres

International Nuclear Information System (INIS)

Woo, Y. K.; Ha, N. Y.; Hwang, Ji Soo; Chang, H. J.; Wu, J. W.

2002-01-01

Photonic crystal is an artificial optical material with a periodic dielectric potential, hence exhibiting a bandgap for a propagating electromagnetic wave. We fabricated crystal possessing 3-D fcc opal structure from silica nanospheres. The crystals are self-assembled on a flat glass by evaporating the solvent in the nanosphere suspension at the room temperature. The suspension consists of silica nanospheres with a diameter of 200 nm. The microscopic arrangement of nanospheres is identified by a scanning electron microscope, the resulting structure being fcc.Transmission spectrum of the fabricated photonic crystal in the visible and near-infrared regions is measured at different incident angles to find the distinct Bragg peaks, analysis of which further confirmed the fcc structure of the photonic crystal. From the optical microscopic image, we find that the opal domain varies from 30 μm to 125 μm in size. In order to relate the observed Bragg peaks with the microscopic arrangement of silica nanospheres, we introduced the scalar wave approximation, where the electric field in the medium is treated as a scalar rather than a vector quantity. It is found that the theoretical prediction of the position of bandgap is in a good agreement with the experimental measurement.

Silicide induced surface defects in FePt nanoparticle fcc-to-fct thermally activated phase transition

International Nuclear Information System (INIS)

Chen, Shu; Lee, Stephen L.; André, Pascal

2016-01-01

Magnetic nanoparticles (MnPs) are relevant to a wide range of applications including high density information storage and magnetic resonance imaging to name but a few. Among the materials available to prepare MnPs, FePt is attracting growing attention. However, to harvest the strongest magnetic properties of FePt MnPs, a thermal annealing is often required to convert face-centered cubic as synthesized nPs into its tetragonal phase. Rarely addressed are the potential side effects of such treatments on the magnetic properties. In this study, we focus on the impact of silica shells often used in strategies aiming at overcoming MnP coalescence during the thermal annealing. While we show that this shell does prevent sintering, and that fcc-to-fct conversion does occur, we also reveal the formation of silicide, which can prevent the stronger magnetic properties of fct-FePt MnPs from being fully realised. This report therefore sheds lights on poorly investigated and understood interfacial phenomena occurring during the thermal annealing of MnPs and, by doing so, also highlights the benefits of developing new strategies to avoid silicide formation.

Silicide induced surface defects in FePt nanoparticle fcc-to-fct thermally activated phase transition

Energy Technology Data Exchange (ETDEWEB)

Chen, Shu; Lee, Stephen L. [School of Physics and Astronomy, SUPA, University of St Andrews, St Andrews KY16 9SS (United Kingdom); André, Pascal, E-mail: pjpandre@riken.jp [School of Physics and Astronomy, SUPA, University of St Andrews, St Andrews KY16 9SS (United Kingdom); RIKEN, Wako 351-0198 (Japan); Department of Physics, CNRS-Ewha International Research Center (CERC), Ewha W. University, Seoul 120-750 (Korea, Republic of)

2016-11-01

Magnetic nanoparticles (MnPs) are relevant to a wide range of applications including high density information storage and magnetic resonance imaging to name but a few. Among the materials available to prepare MnPs, FePt is attracting growing attention. However, to harvest the strongest magnetic properties of FePt MnPs, a thermal annealing is often required to convert face-centered cubic as synthesized nPs into its tetragonal phase. Rarely addressed are the potential side effects of such treatments on the magnetic properties. In this study, we focus on the impact of silica shells often used in strategies aiming at overcoming MnP coalescence during the thermal annealing. While we show that this shell does prevent sintering, and that fcc-to-fct conversion does occur, we also reveal the formation of silicide, which can prevent the stronger magnetic properties of fct-FePt MnPs from being fully realised. This report therefore sheds lights on poorly investigated and understood interfacial phenomena occurring during the thermal annealing of MnPs and, by doing so, also highlights the benefits of developing new strategies to avoid silicide formation.

Size-dependent plastic deformation of twinned nanopillars in body-centered cubic tungsten

Science.gov (United States)

Xu, Shuozhi; Startt, Jacob K.; Payne, Thomas G.; Deo, Chaitanya S.; McDowell, David L.

2017-05-01

Compared with face-centered cubic metals, twinned nanopillars in body-centered cubic (BCC) systems are much less explored partly due to the more complicated plastic deformation behavior and a lack of reliable interatomic potentials for the latter. In this paper, the fault energies predicted by two semi-empirical interatomic potentials in BCC tungsten (W) are first benchmarked against density functional theory calculations. Then, the more accurate potential is employed in large scale molecular dynamics simulations of tensile and compressive loading of twinned nanopillars in BCC W with different cross sectional shapes and sizes. A single crystal, a twinned crystal, and single crystalline nanopillars are also studied as references. Analyses of the stress-strain response and defect nucleation reveal a strong tension-compression asymmetry and a weak pillar size dependence in the yield strength. Under both tensile and compressive loading, plastic deformation in the twinned nanopillars is dominated by dislocation slip on {110} planes that are nucleated from the intersections between the twin boundary and the pillar surface. It is also found that the cross sectional shape of nanopillars affects the strength and the initial site of defect nucleation but not the overall stress-strain response and plastic deformation behavior.

Electrical Power Budget for FCC-ee

CERN Document Server

Aull, S.; Bozzini, D.; Brunner, O.; Burnet, J.-P.; Butterworth, A.; Calaga, R.; Jensen, E.; Mertens, V.; Milanese, A.; Nonis, M.; Oide, K.; Schwerg, N.; Tavian, L.; Wenninger, J.; Zimmermann, F.; Rinolfi, L; Blondel, A.; Koratzinos, M.; Gorgi Zadeh, S.

2016-01-01

We present a first rough estimate for the electrical power consumption of the FCC-ee lepton collider. This electrical power is dominated by the RF system, which provides the motivation for the ongoing R&D on highly efficient RF power sources. Other contributions come from the warm arc magnets, the cryogenics systems, cooling, ventilation, general services, the particle-physics detectors, and the injector complex.

Dislocation nucleation from symmetric tilt grain boundaries in body-centered cubic vanadium

Science.gov (United States)

Xu, Shuozhi; Su, Yanqing

2018-05-01

We perform molecular dynamics (MD) simulations with two interatomic potentials to study dislocation nucleation from six symmetric tilt grain boundaries (GB) using bicrystal models in body-centered cubic vanadium. The influences of the misorientation angle are explored in the context of activated slip systems, critical resolved shear stress (CRSS), and GB energy. It is found that for four GBs, the activated slip systems are not those with the highest Schmid factor, i.e., the Schmid law breaks down. For all misorientation angles, the bicrystal is associated with a lower CRSS than their single crystalline counterparts. Moreover, the GB energy decreases in compressive loading at the yield point with respect to the undeformed configuration, in contrast to tensile loading.

Kinetics of disorder-to-fcc phase transition via an intermediate bcc state

International Nuclear Information System (INIS)

Liu Yongsheng; Nie Huifen; Bansil, Rama; Steinhart, Milos; Bang, Joona; Lodge, Timothy P.

2006-01-01

Time-resolved small-angle x-ray scattering measurements reveal that a long-lived intermediate bcc state forms when a poly(styrene-b-isoprene) diblock copolymer solution in an isoprene selective solvent is rapidly cooled from the disordered micellar fluid at high temperature to an equilibrium fcc state. The kinetics of the epitaxial growth of the [111] fcc peak from the [110] bcc peak was obtained by fitting the scattering data to a simple model of the transformation. The growth of the [111] fcc peak agrees with the Avrami model of nucleation and growth kinetics with an exponent n=1.4, as does the initial decay of the [110] bcc peak, with an exponent n=1.3. The data were also found to be in good agreement with the Cahn model of grain boundary nucleation and growth

Communication government agencies: the case of FCC/ Organismos de regulación y control de las comunicaciones: el caso de la FCC

Directory of Open Access Journals (Sweden)

Dra. Ana I. Segovia Alonso; asegovia@ccinf.ucm.es

2009-01-01

Full Text Available The Federal Communications Commission (FCC is one of the pioneering regulatory agencies in relation to the communication system within the capitalist model. From a general perspective, beginning with its constitution, plan of action, and regulatory decisions, we carry out a research of the historical, political and economic conditions under which this commission operates and was created. The main objective is to outline the reasons for the failures and mistakes of the FCC, that has been accused –since its origins- of acting in defence of the industry interests it seemingly regulates, and not in the public interest; and of being a creature of Congress, with no real independence from the politic, economic, and judiciary power. The final purpose of this essay is to suggest the necessary democratization of the communicative space, which needs an agency transformation that could change the current defence of the existing status quo. La Comisión Federal de Comunicaciones (FCC es uno de los organismos pioneros en el control y regulación del sistema comunicativo en el modelo capitalista. Desde una mirada general a partir de su composición, formas de actuación, y decisiones normativas, se realiza un estudio de los condicionamientos históricos, políticos y económicos bajo los cuales se crea y desarrolla su labor esta Comisión. El objetivo fundamental es delinear las razones de los errores y negligencias de la FCC, acusada desde sus inicios de actuar en defensa de los intereses de la industria a la que pretende regular, y no en interés del público; y de ser una criatura del Congreso sin independencia del poder político, ni económico, ni judicial. El propósito final del presente artículo es plantear la necesaria democratización del espacio comunicativo, que pasa por una transformación de estos organismos y su defensa del status quo existente.

Preparation of nickel and Ni_3Sn nanoparticles via extension of conventional citric acid and ethylene diamine tetraacetic acid mediated sol–gel method

International Nuclear Information System (INIS)

Li, Pingyun; Deng, Guodong; Guo, Xiaode; Liu, Hongying; Jiang, Wei; Li, Fengsheng

2016-01-01

This work aims to extend the application field of sol–gel process from conventional oxides, carbides, sulfides to metallic nanocrystalline materials. Metallic ions were coordinated with chelating agents of citric acid (CA) and ethylene diamine tetraacetic acid (EDTA) in aqueous solution. Then the solutions were dried at 383 K, resulting in the formation of sol and gel. Heating treatments of dried gels were then carried out with protection of N_2 atmosphere. Ni and Ni_3Sn alloy nanoparticles were obtained by this sol–gel method in the range of 623–823 K. The as-prepared Ni and Ni_3Sn alloy nanoparticles have average grain sizes of 15 and 30 nm, and have face-centred-cubic (fcc) crystalline phase. Our results provide new insight into the application of conventional sol–gel method. - Graphical abstract: Sol–gel method is conventionally applied to prepare oxides, carbides, and sulfides. In this work, the application field of sol–gel method is extended to metallic nanoparticles. By using citric acid (CA) and ethylene diamine tetraacetic acid (EDTA) mediated sol–gel method, metallic Ni (a and c) and Ni_3Sn (b and d) alloy nanoparticles can be prepared when the heating treatments are performed under N_2 protecting atmosphere. The Ni and Ni_3Sn nanoparticles have face-centered-cubic (fcc) crystalline phase and ultrafine grain sizes. Diffraction peaks of (110) superstructure reflection plane of Ni_3Sn nanoparticles can also be observed in Figure b, which can be considered as direct evidence of formation of alloy crystalline phase by performing this sol–gel method. - Highlights: • Ni and Ni_3Sn alloy nanoparticles have been prepared by sol–gel processes. • Citric acid and ethylene diamine tetraacetic acid were applied as chelating agent. • Diffraction peak of superstructure reflection plane of Ni_3Sn was detected by XRD. • A novel strategy for preparation of alloy nanoparticles has been presented.

Epitaxial growth of fcc Ti films on Al(001) surfaces

International Nuclear Information System (INIS)

Saleh, A.A.; Shutthanandan, V.; Shivaparan, N.R.; Smith, R.J.; Tran, T.T.; Chambers, S.A.

1997-01-01

High-energy ion scattering (HEIS), x-ray photoelectron spectroscopy, and x-ray photoelectron diffraction (XPD) were used to study the growth of thin Ti films on Al(001) surfaces. The Al surface peak area in the backscattered ion spectrum of MeV He + ions, incident along the [00 bar 1] direction, was used to monitor the atomic structure of the Ti films during growth. An initial decrease in the area was observed indicating epitaxial film growth. This decrease continued up to a critical film thickness of about 5.5 ML, after which point the structure of the film changed. Titanium films 3, 5, and 9 ML thick were characterized using XPD in the same chamber. Both the HEIS and XPD results show that the Ti films grow with an fcc structure on Al(001). A tetragonal distortion of 2.4% in the fcc Ti film was measured using ions incident along the [10 bar 1] direction. Although there is a general similarity of fcc Ti growth on both Al(001) and Al(110), the submonolayer growth regime does show differences for the two surfaces. copyright 1997 The American Physical Society

Cubic colloids : Synthesis, functionalization and applications

NARCIS (Netherlands)

Castillo, S.I.R.

2015-01-01

This thesis is a study on cubic colloids: micron-sized cubic particles with rounded corners (cubic superballs). Owing to their shape, particle packing for cubes is more efficient than for spheres and results in fascinating phase and packing behavior. For our cubes, the particle volume fraction when

First Design of a Proton Collimation System for 50 TeV FCC-hh

CERN Document Server

Fiascaris, Maria; Mirarchi, Daniele; Redaelli, Stefano

2016-01-01

We present studies aimed at defining a first conceptual solution for a collimation system for the hadron-hadron option for the Future Circular Collider (FCC-hh). The baseline collimation layout is based on the scaling of the present LHC collimation system to the FCC-hh energy. It currently includes a dedicated betatron cleaning insertion as well as collimators in the experimental insertions to protect the inner triplets. An aperture model for the FCC-hh is defined and the geometrical acceptance is calculated at top energy taking into account mechanical and optics imperfections. Based on these studies the collimator settings needed to protect the machine are defined. The performance of the collimation system is then assessed with particle tracking simulation tools assuming a perfect machine.

Spectra and energy levels of Eu{sup 3+} in cubic phase Gd{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Smith, Eric R. [Kratos Defense and Security Solutions, Inc., 5030 Bradford Dr., Huntsville, AL 35805 (United States); Gruber, John B. [Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249-0697 (United States); Wellenius, Patrick; Muth, John F. [Department of Electrical and Computer Engineering, NC State University, Raleigh, NC 27606 (United States); Everitt, Henry O. [Department of Physics, Duke University, Durham, NC 27708 (United States); Army Aviation and Missile RD and E Center, Redstone Arsenal, AL 35898 (United States)

2010-07-15

In pulsed laser deposition of the sesquioxide semiconductor Gd{sub 2}O{sub 3}, adjusting the chamber oxygen pressure controls the crystalline structure of the host. This technique was used to deposit thin films of nominally 1.6% by weight europium-doped, cubic phase Gd{sub 2}O{sub 3} using 50 mTorr of oxygen. Structural measurements using high-resolution transmission electron microscopy and selected area electron diffraction confirm the films were polycrystalline, cubic phase Eu:Gd{sub 2}O{sub 3}. The spectroscopic assignment of emission lines to specific radiative transitions within the trivalent Eu ion is confirmed by theoretical analysis of the appropriate crystal field Hamiltonian. Detailed crystal-field splittings are presented for the {sup 5}D{sub J=0-2} and {sup 7}F{sub J=0-5} multiplet manifolds of Eu{sup 3+} in this host material. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Tapering Options and Emittance Fine Tuning for the FCC-ee Collider

OpenAIRE

Härer, Bastian; Doblhammer, Andreas; Holzer, Bernhard

2016-01-01

The lepton collider version of the FCC study describes a future electron-positron collider with a circumference in the order of 100 km, optimised for operation with collision energies in the range of 90 GeV to 350 GeV (FCC- ee). This paper presents the layout of the machine and the constraints on the design of the arc lattice in the context of the four different beam energies that are foreseen for beam operation. Special emphasis is put on the compensation of the effect of the strong synchrot...

Increase of propylene production and recovery in a PETROBRAS FCC units; Aumento da producao e recuperacao de propeno em uma Unidade de FCC da PETROBRAS

Energy Technology Data Exchange (ETDEWEB)

Penna, Elisangela Melo; Pinho, Andrea de Rezende; Wolff, Marcelo Straubel [Petroleo Brasileiro S.A (PETROBRAS), Rio de Janeiro, RJ (Brazil)

2012-07-01

Propylene is one of the major petrochemical raw materials and its demand has been growing rapidly in recent years. Projections for future years indicate that the growth in propylene production via pyrolysis tends to be lower than the growth in the demand for ethylene, creating a supply deficit of this product. The FCC units are in a unique position to meet this increase in propylene demand due to its operational flexibility. Although their primary function in recent decades has been the gasoline production, FCC units are often operated for maximizing other products, such as LPG or distillates. At the FCC conversion section, the increase of propylene yield requires some increase in reaction severity, which can be obtained by increasing reactor riser temperature, and the use of catalyst additives based on ZSM-5. However, besides maximizing the propylene production in the reactor, a second objective should be pursued: the propylene recovery increase in the gas recovery section. In this section, the yield is affected by the gas compressor performance, the equipment design and process scheme. Eventually, new equipment may be installed, such as chillers, aimed at improving the absorption system. Predicting a real increase in propylene demand in the Brazilian market, this study aims to evaluate the adequacy of the gas recovery section of a PETROBRAS FCC unit, analyzing the impacts that a new products yields profile, which bend the propylene production compared to a conventional operation, would cause on this unit. In this paper, the main limitations and modifications that would be needed for an operation were identified, aiming at maximizing the propylene production, as well as proposed changes in the hardware of the unit. (author)

Precision Electroweak measurements at the FCC-ee

CERN Document Server

Dam, Mogens

2016-01-01

Because of a luminosity of up to five orders of magnitude larger than at LEP, electroweak precision measurements at the FCC-ee -- the Future Circular Collider with electron-positron beams -- would provide improvements by orders of magnitude over the present status and constitute a broad search for the existence of new, weakly interacting particles up to very high energy scales. The FCC-ee will address centre-of-mass energies ranging from below the Z pole to the $\\mathrm{t\\bar{t}}$ threshold and above. At energies around the Z pole, the Z-boson mass and width can be measured to better than 100 keV each. Asymmetry measurements at the Z pole allow improvements in the determination of the weak mixing angle by at least a factor 30 to $\\delta\\sin^2\\theta\\mathrm{_W^{eff}}\\simeq 6\\times 10^{-6}$. A determination of the electromagnetic coupling constant at the Z energy scale, $\\alpha_\\mathrm{QED}(m_\\mathrm{Z}^2)$, to a relative precision of $3\\times 10^{-5}$ can be obtained via measurement of the forward-backward asym...

Effect of Eu{sup 3+} doping on the structural and photoluminescence properties of cubic CaCO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Gao, Yan; Sun, Yidi; Zou, Haifeng; Sheng, Ye; Zhou, Xiuqing; Zhang, Bowen; Zhou, Bing, E-mail: zhoubing@jlu.edu.cn

2016-01-15

Graphical abstract: - Highlights: • The doping of Eu{sup 3+} ions decreased the size of CaCO{sub 3} nanoparticles. • The doping of Eu{sup 3+} ions brought about the change of CaCO{sub 3}'s optical bandgap. • Multiple sites of Eu{sup 3+} in CaCO{sub 3} nanocrystals have been identified. - Abstract: CaCO{sub 3}:xEu{sup 3+} (x = 0, 0.010, 0.015, 0.020, and 0.025) cubic nanoparticles were synthesized by carbonation method. The powder XRD patterns and SEM images of the CaCO{sub 3}:xEu{sup 3+} nanoparticles demonstrate that both the crystalline sizes and average particle sizes of synthesized samples decreased with the increase of Eu{sup 3+} content until x = 0.020. Kubelka–Munk plots and bandgap energy estimation indicate that the doping of Eu{sup 3+} ions changed optical bandgap of CaCO{sub 3}. Photoluminescence (PL) spectra show that the PL intensity of the CaCO{sub 3}:xEu{sup 3+} nanoparticles was enhanced with the increase of Eu{sup 3+} content in cubic CaCO{sub 3}:xEu{sup 3+}, and concentration quenching occurred when Eu{sup 3+} concentration exceeded 2.0 mol%. In addition, the doped sites of Eu{sup 3+} in CaCO{sub 3} crystalline were identified by the site-selective spectroscopy and decay curves.

Inherited textures in the bcc phase furnish information about the type of transformation from the fcc phase

International Nuclear Information System (INIS)

Jung, V.

1982-07-01

Drawing annealed cylindric 18/8 Cr Ni steels, which are originally free of textures, produces the transformed phases - hcp and bcc - both showing major texture contributions with increasing stretching of the cylindric specimens. After stretching the original fcc-phase shows two orientations: [100]fcc vertical stroke vertical stroke cylinder axis and [111]fcc vertical stroke vertical stroke cylinder axis, i.e. direction of stress. In both cases the martensitic phase is produced by gliding and shear in the sequence fcc → hcp → bcc by Nishiyama-Wasserman (N-W) or Kurdjumov-Sachs (K-S) transformation in the (111)fcc planes, which enclose a small angle with direction of stress, i.e. cylinder axis. The calculated orientation distributions of the (110)bcc reflex are compared with the distribution measured by neutron diffraction to get information on the bulk material. The special K-S transformation with only 6 (110)bcc orientations shows relatively good agreement with the measured distribution, except at small angles ω between the cylinder axis and the scattering vector. This might be caused by the isotropic fraction of the fcc phase producing an anisotropic (110)bcc orientation distribution. (orig.) [de

76 FR 69738 - Revised 2011 Annual Telecommunications Reporting Worksheet (FCC Form 499-A) and Accompanying...

Science.gov (United States)

2011-11-09

... Telecommunications Reporting Worksheet (FCC Form 499-A) and Accompanying Instructions AGENCY: Federal Communications... Telecommunications Reporting Worksheet (FCC Form 499-A) and accompanying instructions that have been approved by the... INFORMATION CONTACT: Ernesto Beckford, Wireline Competition Bureau, Telecommunications Access Policy Division...

Size Tunable Synthesis of Highly Crystalline BaTiO3 Nanoparticles using Salt-Assisted Spray Pyrolysis

International Nuclear Information System (INIS)

Itoh, Yoshifumi; Lenggoro, I. Wuled; Okuyama, Kikuo; Maedler, Lutz; Pratsinis, Sotiris E.

2003-01-01

Highly crystalline, dense BaTiO 3 nanoparticles in a size range from 30 to 360nm with a narrow size distribution (σ g = 1.2-1.4) were prepared at various synthesis temperatures using a salt-assisted spray pyrolysis (SASP) method without the need for post-annealing. The effect of synthesis temperature on particle size, crystallinity and surface morphology of the nanoparticles were characterized by X-ray diffraction and scanning/transmission electron microscopy. The nature of the crystalline structure was analyzed by Rietveld refinement and Raman spectroscopy. The particle size decreased with decreasing operation temperature. The crystal phase was transformed from tetragonal to cubic at a particles size of about 50nm at room temperature. SASP can be used to produce high weight fraction of tetragonal BaTiO 3 nanoparticles down to 64nm in a single step

Nitrogen Chemistry and Coke Transformation of FCC Coked Catalyst during the Regeneration Process

Science.gov (United States)

Shi, Junjun; Guan, Jianyu; Guo, Dawei; Zhang, Jiushun; France, Liam John; Wang, Lefu; Li, Xuehui

2016-06-01

Regeneration of the coked catalyst is an important process of fluid catalytic cracking (FCC) in petroleum refining, however, this process will emit environmentally harmful gases such as nitrogen and carbon oxides. Transformation of N and C containing compounds in industrial FCC coke under thermal decomposition was investigated via TPD and TPO to examine the evolved gaseous species and TGA, NMR and XPS to analyse the residual coke fraction. Two distinct regions of gas evolution are observed during TPD for the first time, and they arise from decomposition of aliphatic carbons and aromatic carbons. Three types of N species, pyrrolic N, pyridinic N and quaternary N are identified in the FCC coke, the former one is unstable and tends to be decomposed into pyridinic and quaternary N. Mechanisms of NO, CO and CO2 evolution during TPD are proposed and lattice oxygen is suggested to be an important oxygen resource. Regeneration process indicates that coke-C tends to preferentially oxidise compared with coke-N. Hence, new technology for promoting nitrogen-containing compounds conversion will benefit the in-situ reduction of NO by CO during FCC regeneration.

Carbon flow analysis and Carbon emission reduction of FCC in Chinese oil refineries

Science.gov (United States)

Jia, Fengrui; Wei, Na; Ma, Danzhu; Liu, Guangxin; Wu, Ming; Yue, Qiang

2017-08-01

The major problem of the energy production in oil refineries is the high emission of CO2 in China. The fluid catalytic cracking unit (FCC) is the key source of carbon emission in the oil refineries. According to the statistical data, the carbon emission of FCC unit accounts for more than 31% for the typical oil refineries. The carbon flow of FCC in the typical Chinese oil refineries were evaluated and analysed, which aimed at the solution of CO2 emission reduction. The method of substances flow analysis (SFA) and the mathematical programming were used to evaluate the carbon metabolism and optimize the carbon emission. The results indicated that the combustion emission of the reaction-regeneration subsystem (RRS) was the major source of FCC. The quantity of CO2 emission of RSS was more than 90%. The combustion efficiency and the amount of residual oil affected the carbon emission of RRS most according to the optimized analysis of carbon emission reduction. Moreover, the fractionation subsystem (TFS) had the highest environmental efficiency and the absorption-stabilization subsystem (ASS) had the highest resource efficiency (approximately to 1) of carbon.

Cubic superparamagnetic nanoparticles of NiFe{sub 2}O{sub 4} via fast microwave heating

Energy Technology Data Exchange (ETDEWEB)

Galvão, W. S.; Freire, R. M. [Universidade Federal do Ceará–UFC, Grupo de Química de Materiais Avançados (GQMAT), Departamento de Química Analítica e Físico-Química (Brazil); Ribeiro, T. S.; Vasconcelos, I. F. [Universidade Federal do Ceará, Departamento de Engenharia Metalúrgica e de Materiais (Brazil); Costa, L. S. [State University of Campinas–UNICAMP, Department of Inorganic Chemistry, Institute of Chemistry (Brazil); Freire, V. N.; Sales, F. A. M. [Universidade Federal do Ceará, Departamento de Física, Centro de Ciências (Brazil); Denardin, J. C. [Universidad de Santiago de Chile, USACH, Departamento de Física (Chile); Fechine, P. B. A., E-mail: fechine@ufc.br [Universidade Federal do Ceará–UFC, Grupo de Química de Materiais Avançados (GQMAT), Departamento de Química Analítica e Físico-Química (Brazil)

2014-12-15

This study demonstrated the possibility of using microwave heating as a fast and cheap method for synthesizing superparamagnetic nanoparticles. In this sense, NiFe{sub 2}O{sub 4} samples were subjected to microwave heating at various temperatures to determine the lowest temperature at which the crystalline phase of the nanoparticles occurs. X-Ray powder diffraction, {sup 57}Fe Mössbauer spectroscopy, and transmission electron microscopy of the samples were performed to confirm the formed nanoparticles. It was observed a cubic structure of inverse spinel type with good crystallinity. The magnetic properties of the samples were studied using a vibrating sample magnetometer and was found to zero values to remanent magnetization and coercivity field. This behavior suggests superparamagnetic features for all samples. The crystallite size (9, 10, and 12 nm) and saturation magnetization (31–45 emu/g) were used as a function of the increase of the temperature treatment time. Blocking temperature was found by tracing remanent magnetization versus temperature.

Calculations of intersection cross-slip activation energies in fcc metals using nudged elastic band method

International Nuclear Information System (INIS)

Rao, S.I.; Dimiduk, D.M.; Parthasarathy, T.A.; El-Awady, J.; Woodward, C.; Uchic, M.D.

2011-01-01

The nudged elastic band (NEB) method is used to evaluate activation energies for dislocation intersection cross-slip in face-centered cubic (fcc) nickel and copper, to extend our prior work which used an approximate method. In this work we also extend the study by including Hirth locks (HL) in addition to Lomer-Cottrell locks and glide locks (GL). Using atomistic (molecular statics) simulations with embedded atom potentials we evaluated the activation barrier for a dislocation to transform from fully residing on the glide plane to fully residing on the cross-slip plane when intersecting a 120 o forest dislocation in both Ni and Cu. The initial separation between the screw and the intersecting dislocation on the (1 1 1) glide plane is varied to find a minimum in the activation energy. The NEB method gives energies that are ∼10% lower than those reported in our prior work. It is estimated that the activation energies for cross-slip from the fully glide plane state to the partially cross-slipped state at the 120 o intersection forming GL in Ni and Cu are ∼0.47 and ∼0.65 eV, respectively, and from the fully cross-slip plane state to the partially cross-slipped state forming LC are ∼0.68 and ∼0.67 eV. The activation energies for cross-slip from the fully glide plane state to the partially cross-slipped state at the 120 o intersection forming HL in Ni and Cu are estimated to be ∼0.09 and ∼0.31 eV, respectively. These values are a factor of 3-20 lower than the activation energy for bulk cross-slip in Ni and, a factor of 2-6 lower than the activation energy for cross-slip in Cu estimated by Friedel-Escaig analysis. These results suggest that cross-slip should nucleate preferentially at selected screw dislocation intersections in fcc materials and the activation energies for such mechanisms are also a function of stacking fault energy.

An atomistic analysis of the interface mobility in a massive transformation

International Nuclear Information System (INIS)

Bos, C.; Sommer, F.; Mittemeijer, E.J.

2005-01-01

A new multi-lattice kinetic Monte Carlo method has been used for an atomistic study on the interpretation of the interface mobility parameter for a massive face-centred cubic (fcc) to body-centred cubic (bcc) transformation in a single element system. For lateral growth of bcc in a system with an fcc(111)//bcc(110) and fcc[112-bar ]//bcc[001-bar ] interface orientation the overall activation energy for the interface mobility parameter is governed by energetically unfavourable atomic jumps. The atoms on the fcc lattice often cannot jump directly to bcc lattice sites because neighbouring atoms block the empty bcc sites. By single unfavourable jumps and by groups of unfavourable jumps a path from fcc to bcc is created. The necessity of these unfavourable jumps leads to an overall activation energy considerably larger than the activation energy barrier for a single atomic jump

Precision measurement of the top quark mass at threshold with the FCC-ee

CERN Document Server

Foppiani, Nicolo

2016-01-01

The project concerns the study of the sensitivity in measuring the Top quark mass at threshold at the FCC-ee, using a Montecarlo analysis. In particular it has been developed within the FCC software framework, using a fast simulation. The work focused firstly on developing a b-tagging algorithm inside of the FCC fast simulation, managing to obtain results comparable with the ALEPH ones, and new results with a futuristic detector like ILD. Afterwards the selection of the tt events at energy close to the pair production threshold has been studied, obtaining a selection efficiency of 55 % and a background rejection at the level of 99.4 %. In the end, a list of points that can be achieved in the future, to complete the analysis, has been identified.

Microstructure and strengthening mechanisms in an FCC structured single-phase nanocrystalline Co25Ni25Fe25Al7.5Cu17.5 high-entropy alloy

International Nuclear Information System (INIS)

Fu, Zhiqiang; Chen, Weiping; Wen, Haiming; Zhang, Dalong; Chen, Zhen; Zheng, Baolong; Zhou, Yizhang; Lavernia, Enrique J.

2016-01-01

We report on a study of the design, phase formation, microstructure, mechanical behavior and strengthening mechanisms of a novel single-phase Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 (at.%) high-entropy alloy (HEA). In this investigation, a bulk nanocrystalline (nc) Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA with the face-centered cubic (FCC) crystal structure was fabricated by mechanical alloying (MA) followed by consolidation via spark plasma sintering (SPS). The X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed that a single FCC solid-solution phase with an average grain diameter of 24 nm was produced following MA. Following SPS, bulk samples exhibiting a bimodal microstructure with both nanoscale grains and ultra-fine grains (UFGs) and with an average grain diameter of 95 nm were obtained, possessing a single FCC solid-solution phase identical to that in the milled powders. The single-phase feature of the Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA principally resulted from remarkably high mutual solubility in most binary atom-pairs of the constituent elements, which appears to correspond to a high entropy of mixing. Approximately 5 vol.% of nanoscale twins were observed in the bulk nc samples. The bulk nc Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA exhibits a compressive yield strength of 1795 MPa with a hardness of 454 Hv, which is dramatically higher than the yield strength of most previously reported FCC structured HEAs (∼130–700 MPa). Compared to those of the bulk coarse-grained (CG) Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA fabricated by arc-melting, the yield strength and Vickers hardness values of the bulk nc samples increased by 834.9% and 251.9%, respectively. Quantitative calculations of the respective contributions from each strengthening mechanism demonstrate that grain boundary strengthening and dislocation strengthening are principally responsible for the measured ultra-high strength of the bulk nc Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA.

Direct measurement of α_Q_E_D(m_Z"2) at the FCC-ee

International Nuclear Information System (INIS)

Janot, Patrick

2016-01-01

When the measurements from the FCC-ee become available, an improved determination of the standard-model “input' parameters will be needed to fully exploit the new precision data towards either constraining or fitting the parameters of beyond-the-standard-model theories. Among these input parameters is the electromagnetic coupling constant estimated at the Z mass scale, α_Q_E_D(m_Z"2). The measurement of the muon forward-backward asymmetry at the FCC-ee, just below and just above the Z pole, can be used to make a direct determination of α_Q_E_D(m_Z"2) with an accuracy deemed adequate for an optimal use of the FCC-ee precision data.

Anisotropy in the inelastic neutron scattering from fcc NiH

International Nuclear Information System (INIS)

Antonov, V.E.; Fedotov, V.K.; Gnesin, B.A.; Kolesnikov, A.I.; Grosse, G.; Ivanov, A.S.; Wagner, F.E.

2000-01-01

A sample of nearly stoichiometric fcc nickel hydride in the form of polycrystalline plates with strong texture was studied by inelastic neutron scattering (INS) in two different orientations, with the [100] axis of the texture parallel and at an angle of 45 to the direction of neutron momentum transfer. The INS spectra were measured at 5 K with energy transfers ω ranging from 26 to 380 meV. In the region of the second and third band of optical hydrogen vibrations, they showed a significant directional dependence. A similar anisotropy was recently observed in the INS spectrum of fcc palladium hydride, and the now available data for NiH and PdH are discussed together. (orig.)

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-08-07

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

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

KAUST Repository

Borghi, F.

2016-08-05

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

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

KAUST Repository

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

2016-01-01

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

Exploitation of 3D face-centered cubic mesoporous silica as a carrier for a poorly water soluble drug: Influence of pore size on release rate

Energy Technology Data Exchange (ETDEWEB)

Zhu, Wenquan; Wan, Long; Zhang, Chen; Gao, Yikun; Zheng, Xin; Jiang, Tongying; Wang, Siling, E-mail: silingwang@syphu.edu.cn

2014-01-01

The purposes of the present work were to explore the potential application of 3D face-centered cubic mesoporous silica (FMS) with pore size of 16.0 nm as a delivery system for poorly soluble drugs and investigate the effect of pore size on the dissolution rate. FMS with different pore sizes (16.0, 6.9 and 3.7 nm) was successfully synthesized by using Pluronic block co-polymer F127 as a template and adjusting the reaction temperatures. Celecoxib (CEL), which is a BCS class II drug, was used as a model drug and loaded into FMS with different pore sizes by the solvent deposition method at a drug–silica ratio of 1:4. Characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformation infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), nitrogen adsorption, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) was used to systematically investigate the drug loading process. The results obtained showed that CEL was in a non-crystalline state after incorporation of CEL into the pores of FMS-15 with pore size of 16.0 nm. In vitro dissolution was carried out to demonstrate the effects of FMS with different pore sizes on the release of CEL. The results obtained indicated that the dissolution rate of CEL from FMS-15 was significantly enhanced compared with pure CEL. This could be explained by supposing that CEL encountered less diffusion resistance and its crystallinity decreased due to the large pore size of 16.0 nm and the nanopore channels of FMS-15. Moreover, drug loading and pore size both play an important role in enhancing the dissolution properties for the poorly water-soluble drugs. As the pore size between 3.7 and 16.0 nm increased, the dissolution rate of CEL from FMS gradually increased. - Highlights: • Exploitation of 3D cubic mesoporous silica (16 nm) as a carrier was completed. • The release rate of CEL increased on increasing the pore size of carriers. • The crystallinity

Powder metallurgy and mechanical alloying effects on the formation of thermally induced martensite in an FeMnSiCrNi SMA

Directory of Open Access Journals (Sweden)

Pricop Bogdan

2015-01-01

Full Text Available By ingot metallurgy (IM, melting, alloying and casting, powder metallurgy (PM, using as-blended elemental powders and mechanical alloying (MA of 50 % of particle volume, three types of FeMnSiCrNi shape memory alloy (SMA specimens were fabricated, respectively. After specimen thickness reduction by hot rolling, solution treatments were applied, at 973 and 1273 K, to thermally induce martensite. The resulting specimens were analysed by X-ray diffraction (XRD and scanning electron microscopy (SEM, in order to reveal the presence of ε (hexagonal close-packed, hcp and α’ (body centred cubic, bcc thermally induced martensites. The reversion of thermally induced martensites, to γ (face centred cubic, fcc austenite, during heating, was confirmed by dynamic mechanical analysis (DMA, which emphasized marked increases of storage modulus and obvious internal friction maxima on DMA thermograms. The results proved that the increase of porosity degree, after PM processing, increased internal friction, while MA enhanced crystallinity degree.

Kinetics of self-interstitial migration in bcc and fcc transition metals

Science.gov (United States)

Bukkuru, S.; Bhardwaj, U.; Srinivasa Rao, K.; Rao, A. D. P.; Warrier, M.; Valsakumar, M. C.

2018-03-01

Radiation damage is a multi-scale phenomenon. A thorough understanding of diffusivities and the migration energies of defects is a pre-requisite to quantify the after-effects of irradiation. We investigate the thermally activated mobility of self-interstitial atom (SIA) in bcc transition metals Fe, Mo, Nb and fcc transition metals Ag, Cu, Ni, Pt using molecular dynamics (MD) simulations. The self-interstitial diffusion involves various mechanisms such as interstitialcy, dumbbell or crowdion mechanisms. Max-Space Clustering (MSC) method has been employed to identify the interstitial and its configuration over a wide range of temperature. The self-interstitial diffusion is Arrhenius like, however, there is a slight deviation at high temperatures. The migration energies, pre-exponential factors of diffusion and jump-correlation factors, obtained from these simulations can be used as inputs to Monte Carlo simulations of defect transport. The jump-correlation factor shows the degree of preference of rectilinear or rotational jumps. We obtain the average jump-correlation factor of 1.4 for bcc metals and 0.44 for fcc metals. It indicates that rectilinear jumps are preferred in bcc metals and rotational jumps are preferred in fcc metals.

Quasi-crystalline geometry for architectural structures

DEFF Research Database (Denmark)

Weizierl, Barbara; Wester, Ture

2001-01-01

Artikel på CD-Rom 8 sider. The quasi-crystal (QC) type of material was discovered in 1983 by Dan Schechtman from Technion, Haifa. This new crystalline structure of material broke totally with the traditional conception of crystals and geometry introducing non-periodic close packing of cells...... with fivefold symmetry in 3D space. The quasi-crystal geometry can be constructed from two different cubic cells with identical rhombic facets, where the relation between the diagonals is the golden section. All cells have identical rhombic faces, identical edges and identical icosahedral/dedecahedral nodes....... The purpose of the paper is to investigate some possibilities for the application of Quasi-Crystal geometry for structures in architecture. The basis for the investigations is A: to use the Golden Cubes (the two different hexahedra consisting of rhombic facets where the length of the diagonals has the Golden...

Molecular dynamics simulation of temperature effects on deposition of Cu film on Si by magnetron sputtering

Science.gov (United States)

Zhu, Guo; Sun, Jiangping; Zhang, Libin; Gan, Zhiyin

2018-06-01

The temperature effects on the growth of Cu thin film on Si (0 0 1) in the context of magnetron sputtering deposition were systematically studied using molecular dynamics (MD) method. To improve the comparability of simulation results at varying temperatures, the initial status data of incident Cu atoms used in all simulations were read from an identical file via LAMMPS-Python interface. In particular, crystalline microstructure, interface mixing and internal stress of Cu thin film deposited at different temperatures were investigated in detail. With raising the substrate temperature, the interspecies mixed volume and the proportion of face-centered cubic (fcc) structure in the deposited film both increased, while the internal compressive stress decreased. It was found that the fcc structure in the deposited Cu thin films was 〈1 1 1〉 oriented, which was reasonably explained by surface energy minimization and the selectivity of bombardment energy to the crystalline planes. The quantified analysis of interface mixing revealed that the diffusion of Cu atoms dominated the interface mixing, and the injection of incident Cu atoms resulted in the densification of phase near the film-substrate interface. More important, the distribution of atomic stress indicated that the compressive stress was mainly originated from the film-substrate interface, which might be attributed to the densification of interfacial phase at the initial stage of film deposition.

Cesium under pressure: First-principles calculation of the bcc-to-fcc phase transition

Science.gov (United States)

Carlesi, S.; Franchini, A.; Bortolani, V.; Martinelli, S.

1999-05-01

In this paper we present the ab initio calculation of the structural properties of cesium under pressure. The calculation of the total energy is done in the local-density approximation of density-functional theory, using a nonlocal pseudopotential including the nonlinear core corrections proposed by Louie et al. The calculation of the pressure-volume diagram for both bcc and fcc structures allows us to prove that the transition from bcc to fcc structure is a first-order transition.

Pressure-induced structural change from hexagonal to fcc metal lattice in scandium trihydride

International Nuclear Information System (INIS)

Ohmura, A.; Machida, A.; Watanuki, T.; Aoki, K.; Nakano, S.; Takemura, K.

2007-01-01

We synthesized scandium hydrides by hydrogenation of a scandium foil with hydrogen fluid under high pressure at ambient temperature. Scandium dihydride (ScH 2 ) and trihydride (ScH 3 ) were prepared near 4 and 5 GPa, respectively. The hydrogenation process and pressure-induced structural changes in ScH 3 were investigated by synchrotron radiation X-ray diffraction measurements up to 54.7 GPa. A structural transition from hexagonal to the fcc lattice began at 30 GPa and was completed at 46 GPa via an intermediate state similar to those reported for other hexagonal trihydrides. The intermediate state was not interpreted in terms of a coexisting state for the low-pressure hexagonal and the high-pressure fcc structures. The onset transition pressure of ScH 3 supported the previously proposed relation that the hexagonal-fcc transition pressure is inversely proportional to the ionic radius of the trihydride

Pseudomorphic-to-bulk fcc phase transition of thin Ni films on Pd(100)

International Nuclear Information System (INIS)

Rizzi, G.A.; Petukhov, M.; Sedona, F.; Granozzi, G.; Cossaro, A.; Bruno, F.; Cvetko, D.; Morgante, A.; Floreano, L.

2004-01-01

We have measured the transformation of pseudomorphic Ni films on Pd(100) into their bulk fcc phase as a function of the film thickness. We made use of x-ray diffraction and x-ray induced photoemission to study the evolution of the Ni film and its interface with the substrate. The growth of a film with tetragonally strained face centered symmetry (fct) has been observed by out-of-plane x-ray diffraction up to a limit thickness of 10 Ni pseudomorphic layers (some of them partially filled and intermixed with the substrate), where a new fcc bulklike phase is formed. After the formation of the bulklike Ni domains, we observed the pseudomorphic fct domains to disappear preserving the number of layers and their spacing. The phase transition thus proceeds via lateral growth of the bulklike phase within the pseudomorphic one, i.e., the bulklike fcc domains penetrate down to the substrate when formed. This large depth of the walls separating the domains of different phases is also indicated by the increase of the intermixing at the substrate-film interface, which starts at the onset of the transition and continues at even larger thickness. The bulklike fcc phase is also slightly strained; its relaxation towards the orthomorphic lattice structure proceeds slowly with the film thickness, being not yet completed at the maximum thickness presently studied of 30 A (∼17 layers)

Hyperfine interactions in the cubic semiconductor CdO

International Nuclear Information System (INIS)

Desimoni, J.; Bibiloni, A.G.; Massolo, C.P.; Renteria, M.

1990-01-01

The time-differential perturbed angular correlation technique has been applied using 111 In probes, which decay through electron capture to 111 Cd, to study the hyperfine interaction in cubic cadmium oxide, in the temperature range RT--740 degree C (RT denotes room temperature). The main fraction of probes are located in perfect-lattice sites, with null electric field gradient in agreement with crystalline-structure considerations. Around 25% of the total intensity shows an electric-field-gradient distribution around V zz =0. This corresponds to probes located in sites perturbed by the vicinity of oxygen vacancies in the lattice. The temperature-independent behavior of the measured hyperfine parameters is discussed in terms of conductivity and band-structure properties of the semiconductor. No time-dependent interaction arising from nuclear electron-capture aftereffects are seen in this experiment. This is in agreement with a previously reported model of aftereffect processes which states that only holes trapped in impurity levels inside the band gap of the semiconductor can give rise to detectable fluctuating interactions

Hyperfine interactions in the cubic semiconductor CdO

Energy Technology Data Exchange (ETDEWEB)

Desimoni, J.; Bibiloni, A.G.; Massolo, C.P.; Renteria, M. (Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo No. 67, 1900 La Plata, Argentina (AR))

1990-01-15

The time-differential perturbed angular correlation technique has been applied using {sup 111}In probes, which decay through electron capture to {sup 111}Cd, to study the hyperfine interaction in cubic cadmium oxide, in the temperature range RT--740 {degree}C (RT denotes room temperature). The main fraction of probes are located in perfect-lattice sites, with null electric field gradient in agreement with crystalline-structure considerations. Around 25% of the total intensity shows an electric-field-gradient distribution around {ital V}{sub {ital zz}}=0. This corresponds to probes located in sites perturbed by the vicinity of oxygen vacancies in the lattice. The temperature-independent behavior of the measured hyperfine parameters is discussed in terms of conductivity and band-structure properties of the semiconductor. No time-dependent interaction arising from nuclear electron-capture aftereffects are seen in this experiment. This is in agreement with a previously reported model of aftereffect processes which states that only holes trapped in impurity levels inside the band gap of the semiconductor can give rise to detectable fluctuating interactions.

Stacking faults and mechanisms strain-induced transformations of hcp metals (Ti, Mg) during mechanical activation in liquid hydrocarbons

Science.gov (United States)

Lubnin, A. N.; Dorofeev, G. A.; Nikonova, R. M.; Mukhgalin, V. V.; Lad'yanov, V. I.

2017-11-01

The evolution of the structure and substructure of metals Ti and Mg with hexagonal close-packed (hcp) lattice is studied during their mechanical activation in a planetary ball mill in liquid hydrocarbons (toluene, n-heptane) and with additions of carbon materials (graphite, fullerite, nanotubes) by X-ray diffraction, scanning electron microscopy, and chemical analysis. The temperature behavior and hydrogen-accumulating properties of mechanocomposites are studied. During mechanical activation of Ti and Mg, liquid hydrocarbons decay, metastable nanocrystalline titanium carbohydride Ti(C,H) x and magnesium hydride β-MgH2 are formed, respectively. The Ti(C,H) x and MgH2 formation mechanisms during mechanical activation are deformation ones and are associated with stacking faults accumulation, and the formation of face-centered cubic (fcc) packing of atoms. Metastable Ti(C,H)x decays at a temperature of 550°C, the partial reverse transformation fcc → hcp occurs. The crystalline defect accumulation (nanograin boundaries, stacking faults), hydrocarbon destruction, and mechanocomposite formation leads to the enhancement of subsequent magnesium hydrogenation in the Sieverts reactor.

Sulfur and octane trade off in FCC naphta conventional hydrotreating

Energy Technology Data Exchange (ETDEWEB)

Badra, C. [INTEVEP S.A. Research and Technological Support Center of Petroleos de Venzuela, Caracas (Venezuela). Dept. de Refinacion; Perez, J.A. [INTEVEP S.A. Research and Technological Support Center of Petroleos de Venzuela, Caracas (Venezuela). Dept. de Refinacion; Salazar, J.A. [INTEVEP S.A. Research and Technological Support Center of Petroleos de Venzuela, Caracas (Venezuela). Dept. de Refinacion; Cabrera, L. [INTEVEP S.A. Research and Technological Support Center of Petroleos de Venzuela, Caracas (Venezuela). Dept. de Refinacion; Gracia, W. [INTEVEP S.A. Research and Technological Support Center of Petroleos de Venzuela, Caracas (Venezuela). Dept. de Refinacion

1997-06-01

A model to predict the change of octane numbers expected in an FCC naphtha hydrotreating process as a function of the hydroprocessing severity (degree of sulfur removal) and the type of naphtha (expressed as the sulfur content and bromine number in the feedstock) is presented. When considering hydrotreating as an option for processing their catalytic naphthas, refiners search for the proper balance between the desired reduction of sulfur and olefins and the resulting undesired reduction of octane (RON and MON). In doing so, refiners should study the possibility of performing the hydrotreating at mild severities and/or the possibility of fractionating FCC naphthas to just treat a specific cut. This paper provides simple tools to study and analyze these study cases and to assess the sulfur-octane trade offs. (orig.)

Experimental study of the spin density of metastable fcc ferromagnetic Fe-Cu alloys

International Nuclear Information System (INIS)

Bove, L. E.; Petrillo, C.; Sacchetti, F.; Mazzone, G.

2000-01-01

Magnetization density measurements on metastable Fe x Cu 1-x alloys at four compositions (x=20, 40, 50, and 60 at. %) and at 5 K temperature were carried out by means of polarized neutron diffraction. The samples were produced by high-energy ball milling and characterized by x-ray diffraction and fluorescence measurements. Additional bulk magnetization measurements were carried out on the two samples at high Fe concentration. Over the present concentration region, the Fe-Cu system is ferromagnetic and the four samples were found to be in the fcc phase. Fe-Cu is therefore a very suitable system to investigate the magnetic state of Fe in an fcc environment. Other than confirming that the Fe-Cu system is not a simple dilution alloy, the present results were compatible with a two-state model for fcc Fe--that is, two different coexisting electronic states associated with different magnetic moments and form factors

Updates on the optics of the future hadron-hadron collider FCC-hh

CERN Document Server

AUTHOR|(CDS)2093721; Boutin, David Jean Henri; Dalena, Barbara; Holzer, Bernhard; Langner, Andy Sven; Schulte, Daniel

2017-01-01

The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group. The layout of FCC-hh has been optimized to a more compact design following recommendations from civil engineering aspects. The updates on the first order and second order optics of the ring will be shown for collisions at the required centre-of-mass energy of 100 TeV. Special emphasis is put on the dispersion suppressors and general beam cleaning sections as well as first considerations of injection and extraction sections.

Effect of cooling rate on microstructure and deformation behavior of Ti-based metallic glassy/crystalline powders

Energy Technology Data Exchange (ETDEWEB)

Wang, D.J. [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD 4072 (Australia); Huang, Y.J. [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); Shen, J., E-mail: junshen@hit.edu.cn [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); Wu, Y.Q.; Huang, H. [School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD 4072 (Australia); Zou, J., E-mail: j.zou@uq.edu.au [School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD 4072 (Australia); Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, QLD 4072 (Australia)

2010-08-20

The microstructures and deformation behavior of Ti-based metallic powders were comprehensively investigated. It has been found that, with increasing the powder size, the phase constituent alters from pure glassy to glassy with crystalline phases (face centered cubic structured NiSnZr and hexagonal structured Ti{sub 3}Sn phases). Our results suggest that the synergetic effect of the thermodynamics and kinetics determines the subsequent characteristics of the crystalline precipitations. Through comparative nanoindentation tests, it was found that the small powders exhibit more pop-in events and a larger pile-up ratio, suggesting that the plastic deformation of the metallic powders is governed by the combined effects of the free volume and the crystallization, which are determined by the cooling rate.

Heat capacities, third-law entropies and thermodynamic functions of the negative thermal expansion materials, cubic {alpha}-ZrW{sub 2}O{sub 8} and cubic ZrMo{sub 2}O{sub 8}, from T=(0 to 400) K

Energy Technology Data Exchange (ETDEWEB)

Stevens, Rebecca; Linford, Jessica; Woodfield, Brian F.; Boerio-Goates, Juliana. E-mail: boerio-goates@byu.edu; Lind, Cora; Wilkinson, Angus P.; Kowach, Glen

2003-06-01

The molar heat capacities of crystalline cubic {alpha}-ZrW{sub 2}O{sub 8} and cubic ZrMo{sub 2}O{sub 8} have been measured at temperatures from (0.6 to 400) K. At T=298.15 K, the standard molar heat capacities are (207.01{+-}0.21) J{center_dot}K{sup -1}{center_dot}mol{sup -1} for the tungstate and (210.06{+-}0.42) J{center_dot}K{sup -1}{center_dot}mol{sup -1} for the molybdate. Thermodynamic functions have been generated from smoothed fits of the experimental results. The standard molar entropies for the tungstate and molybdate are (257.96{+-}0.50) J{center_dot}K{sup -1}{center_dot}mol{sup -1} and (254.3{+-}1) J{center_dot}K{sup -1}{center_dot}mol{sup -1}, respectively. The uncertainty of the entropy of the cubic ZrMo{sub 2}O{sub 8} is larger due to the presence of small chemical and phase impurities whose effects cannot be corrected for at this time. The heat capacities of the negative thermal expansion materials have been compared to the weighted sums of their constituent binary oxides. Both negative thermal expansion materials have heat capacities which are significantly greater than the sum of the binary oxides over the entire temperature region.

Interpolation of natural cubic spline

Directory of Open Access Journals (Sweden)

Arun Kumar

1992-01-01

Full Text Available From the result in [1] it follows that there is a unique quadratic spline which bounds the same area as that of the function. The matching of the area for the cubic spline does not follow from the corresponding result proved in [2]. We obtain cubic splines which preserve the area of the function.

Quantitative comparison between simulated and experimental FCC rolling textures

DEFF Research Database (Denmark)

Wronski, M.; Wierzbanowski, K.; Leffers, Torben

2015-01-01

The degree of similarity between simulated and experimental fcc rolling textures is characterized by a single scalar parameter. The textures are simulated with a relatively simple and efficient 1-point model which allows us to vary the strength of the interaction between the grains and the surrou...

Deformation microstructure and orientation of F.C.C. crystals

DEFF Research Database (Denmark)

Liu, Q.; Hansen, N.

1995-01-01

The effect of crystallographic orientation on the microstructural evolution in f.c.c. metals with medium to high stacking fault energy is analyzed. This analysis is based on a literature review of the behaviour of single crystals and polycrystals supplemented with an experimental study of cold...

Maximizing light olefins production in fluid catalytic cracking (FCC) units; Maximizacao de olefinas leves em unidades de craqueamento catalitico fluido

Energy Technology Data Exchange (ETDEWEB)

Pimenta, Ricardo D.M.; Pinho, Andrea de Rezende [PETROBRAS, Rio de Janeiro, RJ (Brazil)

2004-07-01

The Fluid Catalytic Cracking (FCC) process is widely spread over the ten PETROBRAS refineries in its thirteen industrial units. The importance of the FCC process resides on its high gasoline output, being the main supplier of this important product to the system. Additionally, FCC process is the main source of light hydrocarbons in the LPG range, including light olefins. The increasing demand for ethylene, propylene and butylenes was encouraging to concentrate the research efforts on studies about alternatives for the traditional FCC process. In the present work, the proposals from main licensors (UOP, KBR, Stone and Webster) for a light-olefins-driven FCC process (Petrochemical FCC) will be compared. Furthermore, the catalytic route for light olefins production in FCC units is also described. An additive based on ZSM- 5 zeolite, which is produced following a PETROBRAS proprietary technology, is being largely applied into the catalyst inventories of all FCC units. An analysis of different scenarios was performed to estimate the maximum potential of light olefins production from the highest possible ZSM-5 additive usage. More specifically for the case of ethylene, which production is also boosted by the same type of additive, studies are being conducted with the objective of recovering it from a C2 stream using specific units to do the splitting (UPGR). The search for increasing light olefins production in the refining processes is in line with PETROBRAS strategic plan which targeted for the company a more intense activity in the Brazilian petrochemical market (author)

Dynamic Aperture Studies for the FCC-ee

CERN Document Server

Medina, L; Tomas, R; Zimmermann, F

2015-01-01

Dynamic aperture (DA) studies have been conducted on the latest Future Circular Collider – ee (FCC-ee) lattices as a function of momentum deviation.Two different schemes for the interaction region are used, which are connected to the main arcs: the crab waist approach, developed by BINP, and an update to the CERN design where the use of crab cavities is envisioned. The results presented show an improvement in the performance of both designs.

Beam-beam studies for FCC-hh

CERN Document Server

AUTHOR|(CDS)2068329; Pieloni, Tatiana; Buffat, Xavier; Furuseth, Sondre Vik

2017-01-01

The Future Circular Collider hadron-hadron (FCC-hh) design study is currently exploring different IR design possibilities including round and flat optics or different crossing schemes. The present study intends to evaluate each scenario from the beam-beam effects point of view. In particular the single particle long term stability to maximize beam lifetimes and luminosity reach is used to quantify the differences. The impact of strong head on interactions on the beam quality and lifetime is addressed by means of GPU accelerated simulations code featuring a weak-strong 6-dimensional beam-beam interaction.

75 FR 62818 - Sunshine Act Meeting; FCC To Hold Open Commission Meeting Thursday, October 14, 2010

Science.gov (United States)

2010-10-13

... changes to the FCC's CableCARD rules to improve the consumer experience with the video navigation devices... Connection also will carry the meeting live via the Internet. To purchase these services call (703) 993-3100... purchased from the FCC's duplicating contractor, Best Copy and Printing, Inc. (202) 488-5300; Fax (202) 488...

Density fluctuation in a screened Coulombic colloid dispersion: comparison of the liquid and cubic phases of lipid A-diphosphate

International Nuclear Information System (INIS)

Brown, Helen; Ross, D. Keith; Paradies, Henrich H.

2004-01-01

Light-, small-angle X-ray and neutron scattering measurements of the dynamic structure factor S(Q,t) of strong interacting dispersions of lipid A-diphosphate were recorded and analysed applying existing models of liquid state theory. Lipid A-diphosphate ordering was observed at low volume fractions (phi=2.2x10 -4 ) and at very low ionic strength (I=10 -5 M). Upon increasing the particle number density of lipid A-diphosphate a transformation of the lattices of the colloidal crystals from a BCC lattice (a=36.20 nm) to a FCC lattice (a=57.30 nm) occurred. This strongly suggests a similarity in the preformed liquid structure and the cubic colloidal phase. The fit of both S eff (Q) and the principle peak I p (Q) with the effective particle charge supports of the main conclusions drawn from the SANS experiments and the liquid state theory indicating the presence of long-range order for the dispersions of lipid A-diphosphate

Defect production rates by electrons, ions and neutrons in cubic metals

International Nuclear Information System (INIS)

Jung, P.; Nielsen, B.R.; Andersen, H.H.

1982-01-01

The results of an interlaboratory program to study low temperature damage rates in dilute alloys of 300 ppM Zr in vanadium, niobium and molybdenum with electrons, light ions, fission neutrons and high energy neutrons are summarized. Additional experiments and literature data supplied complete sets of data also for the fcc metals Al, Cu and Pt. From the initial damage rates, displacement functions for each material were derived which give the number of stable defects produced by a recoil event of a certain knock-on energy. The low and high energy part of the displacement function was determined from the results of the electron and neutron irradiations, respectively, while the light ion data supplied information on the intermediate energy range. The displacement function allows the reliable calculation of atomic displacement rates also for particles and/or energies not employed in this program. For all metals the displacement rates for high energy neutrons scaled reasonably with the minimum displacement energies. This allows to estimate neutron damage rates also for those cubic metals where no high energy neutron results are available. For stainless steel, e.g., an average displacement energy of about 120 eV is deduced. The results are suggested to find practical use in defect calculations for fusion reactor first wall technology and in correlating the corresponding simulation experiments

A newly developed maneuver, field change conversion (FCC), improved evaluation of the left ventricular volume more accurately on quantitative gated SPECT (QGS) analysis

International Nuclear Information System (INIS)

Tajima, Osamu; Shibasaki, Masaki; Hoshi, Toshiko; Imai, Kamon

2002-01-01

The purpose of this study was to investigate whether a newly developed maneuver that reduces the reconstruction area by a half more accurately evaluates left ventricular (LV) volume on quantitative gated SPECT (QGS) analysis. The subjects were 38 patients who underwent left ventricular angiography (LVG) followed by G-SPECT within 2 weeks. Acquisition was performed with a general purpose collimator and a 64 x 64 matrix. On QGS analysis, the field magnification was 34 cm in original image (Original: ORI), and furthermore it was changed from 34 cm to 17 cm to enlarge the re-constructed image (Field Change Conversion: FCC). End-diastolic volume (EDV) and end-systolic volume (ESV) of the left ventricle were also obtained using LVG. EDV was 71±19 ml, 83±20 ml and 98±23 ml for ORI, FCC and LVG, respectively (p<0.001: ORI versus LVG, p<0.001: ORI versus FCC, p<0.001: FCC versus LVG). ESV was 28±12 ml, 34±13 ml and 41±14 ml for ORI, FCC and LVG, respectively (p<0.001: ORI versus LVG, p<0.001: ORI versus FCC, p<0.001: FCC versus LVG). FCC was better than ORI for calculating LV volume in clinical cases. Furthermore, FCC is a useful method for accurately measuring the LV volume on QGS analysis. (author)

Prediction of physicochemical properties of FCC feedstock by Chemometric analysis of their ultraviolet spectrum

International Nuclear Information System (INIS)

Baldrich Ferrer, Carlos A

2008-01-01

Chemometric analysis by Partial Least Squares (PLS) has been applied in this work to correlate the ultraviolet spectrum of combined Fluid Catalytic Cracking (FCC) feedstock with their physicochemical properties. The prediction errors obtained in the validation process using refinery samples demonstrate the accuracy of the predicted properties. This new analytical methodology allows obtaining in one analysis detailed information about the most important physicochemical properties of FCC feedstock and could be used as a valuable tool for operational analysis

Crystallization characteristics of Mg-doped Ge2Sb2Te5 films for phase change memory applications

International Nuclear Information System (INIS)

Fu Jing; Shen Xiang; Nie Qiuhua; Wang Guoxiang; Wu Liangcai; Dai Shixun; Xu Tiefeng; Wang, R.P.

2013-01-01

Highlights: ► Mg-doped Ge 2 Sb 2 Te 5 (GST) phase change films with higher resistance and better thermal stability have been proposed. ► The increase of Mg content result in an enhancement in crystallization temperature, activation energy and electrical resistance. ► The proper Mg addition in GST can lead to a one-step crystallization process from amorphous to faced-centered cubic (fcc) phase. ► The formation of covalent Mg-Sb and Mg-Te bonds contribute to the enhancement thermal stability in Mg-doped GST films. - Abstract: Mg-doped Ge 2 Sb 2 Te 5 (GST) films with different Mg doping concentrations have been prepared, and their crystallization behavior, structure and electrical properties have been systematically investigated for phase-change memory applications. The results show that the addition of Mg into GST films could result in an enhancement in crystallization temperature, activation energy and electrical resistance compared with the conventional GST films, indicating that a good amorphous thermal stability. On the other hand, the proper Mg concentration ranging from 13.6 to 31.1 at.% can lead to a one-step crystallization process from amorphous to faced-centered cubic (fcc) phase and suppress the formation of the hexagonal close-packed (hcp) crystalline phase. X-ray photoelectron spectra (XPS) further confirm that the formation of covalent Mg-Sb and Mg-Te bonds contribute to the enhanced thermal stability in Mg-doped GST films.

Growth of metastable fcc Mn thin film on GaAs(001) and its electronic structure studied by photoemission with synchrotron radiation

International Nuclear Information System (INIS)

Chen Yan; Dong Guosheng; Zhang Ming

1995-01-01

The epitaxial growth of metastable fcc Mn thin films on GaAs(001) surface has been achieved at a substrate temperature of 400 K. The development of the fcc Mn thin films as a function of coverage is studied by photoemission with synchrotron radiation. The electron density of states below the Fermi edge of the fcc Mn phase is measured. A significant difference of the electronic structures is observed between the metastable fcc Mn phase and the thermodynamically stable α-Mn phase. Possible mechanisms are proposed to interpret the experimental result

Diffusivities and atomic mobilities in Cu-rich fcc Al-Cu-Mn alloys

Energy Technology Data Exchange (ETDEWEB)

Yin, Ming; Du, Yong; Cui, Senlin; Xu, Honghui; Liu, Shuhong [Central South Univ., Changsha (China). State Key Laboratory of Powder Metallurgy; Zhang, Lijun [Bochum Univ. (DE). Interdisciplinary Centre for Advanced Materials Simulation (ICAMS)

2012-07-15

Via solid-solid diffusion couples, electron probe microanalysis and the Whittle and Green method, interdiffusivities in fcc Al-Cu-Mn alloys at 1 123 K were measured. The reliability of the obtained diffusivities is validated by comparing the computed diffusivities with literature data plus constraints among the diffusivities. Through assessments of experimentally determined diffusion coefficients by means of a diffusion-controlled transformations simulation package, the atomic mobilities of Al, Cu, and Mn in fcc Al-Cu-Mn alloys are obtained. Comprehensive comparisons between the model-predicted and the experimental data indicate that the presently obtained atomic mobilities can reproduce most of the diffusivities, concentration profiles, and diffusion paths reasonably. (orig.)

Cubic boron nitride (cBN) - A new material for advanced optoelectronic devices. Properties and perspectives

International Nuclear Information System (INIS)

Nistor, S.V.; Nistor, L.C.; Dinca, G.

2001-01-01

Cubic boron nitride (cBN) exhibits, besides exceptional thermal and mechanical properties similar to diamond, an excellent ability to be n or p doped, which makes it a strong candidate for advanced, high - temperature optical and microelectronic devices. Despite its outstanding characteristics, there are quite a few reports concerning the physical properties of cBN. This is partly due to the absence of natural cBN gems and the extreme difficulties in producing enough large (mm 3 sized) single crystals, or single phase thin films, for physical characterization. The state of the art knowledge concerning the basic properties of crystalline cBN, as well as our recent results of microstructure and defect properties studies will be presented. (authors)

Ternary diffusion in Cu-rich fcc Cu–Al–Si alloys at 1073 K

Energy Technology Data Exchange (ETDEWEB)

Liu, Dandan [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Zhang, Lijun [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Du, Yong, E-mail: yongducalphad@gmail.com [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Xu, Honghui [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Jin, Zhanpeng [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China)

2013-07-25

Highlights: •Interdiffusivities in Cu-rich fcc Cu–Al–Si alloys at 1073 K were determined. •The present results were compared with experimental data in boundary binary systems. •The present results were validated by thermodynamic constraints and Fick’s law. •The sign of ternary cross diffusivities was predicted in terms of thermodynamics. -- Abstract: Utilizing six groups of bulk diffusion couples and with electron probe microanalysis technique, the composition dependence of ternary interdiffusion coefficients in Cu-rich fcc Cu–Al–Si alloys at 1073 K were determined by the Matano-Kirkaldy method. Using a three-dimensional representation, the obtained main ternary diffusion coefficients were found to be consistent with the experimental data in boundary binaries available in the literature. The reliability of the obtained interdiffusivities was further validated by thermodynamic constraints as well as by Fick’s second law applied to numerical simulation. The sign of the ternary cross diffusivities in fcc Cu–Al–Si alloys, which shows a noticeable effect on microstructure, was also successfully predicted in terms of thermodynamics.

Ternary diffusion in Cu-rich fcc Cu–Al–Si alloys at 1073 K

International Nuclear Information System (INIS)

Liu, Dandan; Zhang, Lijun; Du, Yong; Xu, Honghui; Jin, Zhanpeng

2013-01-01

Highlights: •Interdiffusivities in Cu-rich fcc Cu–Al–Si alloys at 1073 K were determined. •The present results were compared with experimental data in boundary binary systems. •The present results were validated by thermodynamic constraints and Fick’s law. •The sign of ternary cross diffusivities was predicted in terms of thermodynamics. -- Abstract: Utilizing six groups of bulk diffusion couples and with electron probe microanalysis technique, the composition dependence of ternary interdiffusion coefficients in Cu-rich fcc Cu–Al–Si alloys at 1073 K were determined by the Matano-Kirkaldy method. Using a three-dimensional representation, the obtained main ternary diffusion coefficients were found to be consistent with the experimental data in boundary binaries available in the literature. The reliability of the obtained interdiffusivities was further validated by thermodynamic constraints as well as by Fick’s second law applied to numerical simulation. The sign of the ternary cross diffusivities in fcc Cu–Al–Si alloys, which shows a noticeable effect on microstructure, was also successfully predicted in terms of thermodynamics

Cubical sets as a classifying topos

DEFF Research Database (Denmark)

Spitters, Bas

Coquand’s cubical set model for homotopy type theory provides the basis for a computational interpretation of the univalence axiom and some higher inductive types, as implemented in the cubical proof assistant. We show that the underlying cube category is the opposite of the Lawvere theory of De...... Morgan algebras. The topos of cubical sets itself classifies the theory of ‘free De Morgan algebras’. This provides us with a topos with an internal ‘interval’. Using this interval we construct a model of type theory following van den Berg and Garner. We are currently investigating the precise relation...

Generalized Vaidya spacetime for cubic gravity

Science.gov (United States)

Ruan, Shan-Ming

2016-03-01

We present a kind of generalized Vaidya solution of a new cubic gravity in five dimensions whose field equations in spherically symmetric spacetime are always second order like the Lovelock gravity. We also study the thermodynamics of its spherically symmetric apparent horizon and get its entropy expression and generalized Misner-Sharp energy. Finally, we present the first law and second law hold in this gravity. Although all the results are analogous to those in Lovelock gravity, we in fact introduce the contribution of a new cubic term in five dimensions where the cubic Lovelock term is just zero.

New lipid family that forms inverted cubic phases in equilibrium with excess water: molecular structure-aqueous phase structure relationship for lipids with 5,9,13,17-tetramethyloctadecyl and 5,9,13,17-tetramethyloctadecanoyl chains.

Science.gov (United States)

Yamashita, Jun; Shiono, Manzo; Hato, Masakatsu

2008-10-02

With a view to discovering a new family of lipids that form inverted cubic phases, the aqueous phase behavior of a series of lipids with isoprenoid-type hydrophobic chains has been examined over a temperature range from -40 to 65 degrees C by using optical microscopy, DSC (differential scanning calorimetry), and SAXS (small-angle X-ray scattering) techniques. The lipids examined are those with 5,9,13,17-tetramethyloctadecyl and 5,9,13,17-tetramethyloctadecanoyl chains linked to a series of headgroups, that is, erythritol, pentaerythritol, xylose, and glucose. All of the lipid/water systems displayed a "water + liquid crystalline phase" two-phase coexistence state when sufficiently diluted. The aqueous phase structures of the most diluted liquid crystalline phases in equilibrium with excess water depend both on the lipid molecular structure and on the temperature. Given an isoprenoid chain, the preferred phase consistently follows a phase sequence of an H II (an inverted hexagonal phase) to a Q II (an inverted bicontinuous cubic phase) to an L alpha (a lamellar phase) as A* (cross-section area of the headgroup) increases. For a given lipid/water system, the phase sequence observed as the temperature increases is L alpha to Q II to H II. The present study allowed us to find four cubic phase-forming lipid species, PEOC 18+4 [mono- O-(5,9,13,17-tetramethyloctadecyl)pentaerythritol], beta-XylOC 18+4 [1- O-(5,9,13,17-tetramethyloctadecyl)-beta- d-xylopyranoside], EROCOC 17+4 [1- O-(5,9,13,17-tetramethyloctadecanoyl)erythritol], and PEOCOC 17+4 [mono- O-(5,9,13,17-tetramethyloctadecanoyl)pentaerythritol]. The values of T K (hydrated solid-liquid crystalline phase transition temperature) of the cubic phase-forming lipids are all below 0 degrees C. Quantitative analyses of the lipid molecular structure-aqueous phase structure relationship in terms of the experimentally evaluated "surfactant parameter" allow us to rationally select an optimum combination of hydrophilic

Low temperature formation of higher-k cubic phase HfO2 by atomic layer deposition on GeOx/Ge structures fabricated by in-situ thermal oxidation

International Nuclear Information System (INIS)

Zhang, R.; Huang, P.-C.; Taoka, N.; Yokoyama, M.; Takenaka, M.; Takagi, S.

2016-01-01

We have demonstrated a low temperature formation (300 °C) of higher-k HfO 2 using atomic layer deposition (ALD) on an in-situ thermal oxidation GeO x interfacial layer. It is found that the cubic phase is dominant in the HfO 2 film with an epitaxial-like growth behavior. The maximum permittivity of 42 is obtained for an ALD HfO 2 film on a 1-nm-thick GeO x form by the in-situ thermal oxidation. It is suggested from physical analyses that the crystallization of cubic phase HfO 2 can be induced by the formation of six-fold crystalline GeO x structures in the underlying GeO x interfacial layer

A Guide to Federal Regulation; Understanding the FCC Rules.

Science.gov (United States)

Cable Television Information Center, Washington, DC.

While it is apparent that the Federal Communications Commission (FCC) has given a great deal of thought to the regulation of cable systems, the basic success or failure of cable as a communications service will depend on local development. Relatively little guidance has been provided to local franchising authorities for selecting among applicants,…

Effect of the coupling between electronic structure and crystalline structure on some properties of transition metals; Couplage entre structure electronique et structure cristalline: effet sur quelques proprietes des metaux de transition

Energy Technology Data Exchange (ETDEWEB)

Nastar, M

1994-10-14

The elastic constants, energetic stabilities and vacancy formation energies in transition metals are calculated within a Tight Binding model. In order to outline the effect of the electronic structure, these properties are represented as functions of band filling. The variation of the shear elastic constants of hexagonal close packed (HCP), body centered cubic (BCC) and face centered cubic (FCC) structures, is in contrast with the roughly parabolic behavior of bulk modulus. The general trends are in very good agreement with available experimental and `ab initio` data. The vacancy formation energy in the BCC structure shows strong deviations from bell shape behavior with a maximum corresponding approximately to the band filling of group 6. This band filling effect contributes to the noticeable decrease of the self diffusion rate between group 4 and group 6. We demonstrate that the abrupt increase of the C` elastic constant, the NT{sub 1} (0.-1.1) phonon frequency, the energy differences between BCC and HCP and between FCC and HCP as well as the vacancy formation energy, that occurs when going from Zr to Mo, is related to the presence of a pseudo-gap in the density of states of the BCC structure. Using the recursion method, we show that the general trends of these properties are correctly reproduced when considering only a few moments of the density of states (about 6). On the other hand, details such as the elastic constant singularities, are displayed only with an exact calculation of the density of states. (Author). 173 refs., 84 figs., 5 tabs.

High-quality single crystalline NiO with twin phases grown on sapphire substrate by metalorganic vapor phase epitaxy

Directory of Open Access Journals (Sweden)

Kazuo Uchida

2012-12-01

Full Text Available High-quality single crystalline twin phase NiO grown on sapphire substrates by metalorganic vapor phase epitaxy is reported. X-ray rocking curve analysis of NiO films grown at different temperatures indicates a minimum full width at half maximum of the cubic (111 diffraction peak of 0.107° for NiO film grown at as low as 550 °C. Detailed microstructural analysis by Φ scan X-ray diffraction and transmission electron microscopy reveal that the NiO film consists of large single crystalline domains with two different crystallographic orientations which are rotated relative to each other along the [111] axis by 60°. These single crystal domains are divided by the twin phase boundaries.

Self-assembled liquid crystalline nanoparticles as a novel ophthalmic delivery system for dexamethasone: Improving preocular retention and ocular bioavailability.

Science.gov (United States)

Gan, Li; Han, Shun; Shen, Jinqiu; Zhu, Jiabi; Zhu, Chunliu; Zhang, Xinxin; Gan, Yong

2010-08-30

The object of this study was to design novel self-assembled liquid crystalline nanoparticles (cubosomes) as an ophthalmic delivery system for dexamethasone (DEX) to improve its preocular retention and ocular bioavailability. DEX cubosome particles were produced by fragmenting a cubic crystalline phase of monoolein and water in the presence of stabilizer Poloxamer 407. Small angle X-ray diffraction (SAXR) profiles revealed its internal structure as Pn3m space group, indicating the diamond cubic phase. In vitro, the apparent permeability coefficient of DEX administered in cubosomes exhibited a 4.5-fold (F1) and 3.5-fold (F2) increase compared to that of Dex-Na phosphate eye drops. Preocular retention studies revealed that the retention of cubosomes was significantly longer than that of solution and carbopol gel, with AUC(0-->180min) of Rh B cubosomes being 2-3-fold higher than that of the other two formulations. In vivo pharmacokinetics in aqueous humor was evaluated by microdialysis, which indicated a 1.8-fold (F1) increase in AUC(0-->240min) of DEX administered in cubosomes relative to that of Dex-Na phosphate eye drops, with about an 8-fold increase compared to that of DEX suspension. Corneal cross-sections after incubation with DEX cubosomes demonstrated an unaffected corneal structure and tissue integrity, which indicated the good biocompatibility of DEX cubosomes. In conclusion, self-assembled liquid crystalline nanoparticles might represent a promising vehicle for effective ocular drug delivery. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

Spinning solitons in cubic-quintic nonlinear media

Indian Academy of Sciences (India)

Spinning solitons in cubic-quintic nonlinear media ... features of families of bright vortex solitons (doughnuts, or 'spinning' solitons) in both conservative and dissipative cubic-quintic nonlinear media. ... Pramana – Journal of Physics | News.

On the nature of the dhcp to fcc transition under pressure in Pr and Pr-Th alloys

International Nuclear Information System (INIS)

Vijayakumar, V.; Godwal, B.K.; Sikka, S.K.; Chidambaram, R.

1988-01-01

The results of electrical resistance (R), thermoelectric power (TEP) and X-ray diffraction measurements on praseodymium (Pr) and its alloys with thorium under pressure are reported. The maximum in R vs P curve exhibited by Pr persists only in the dhcp phase of Pr-Th alloy. X-ray measurements confirmed that in the alloys also the maximum in R vs P curve is due to the dhcp → fcc transition. Thus the behaviour of Pr and Pr-Th alloys is different from that of La and its alloys with Ce and Th where the maximum in the R vs P curve is electronic in origin and is exhibited by the dhcp, fcc and dist fcc phases. (author). 14 refs

Iron Contamination Mechanism and Reaction Performance Research on FCC Catalyst

Directory of Open Access Journals (Sweden)

Zhaoyong Liu

2015-01-01

Full Text Available FCC (Fluid Catalytic Cracking catalyst iron poisoning would not only influence units’ product slate; when the poisoning is serious, it could also jeopardize FCC catalysts’ fluidization in reaction-regeneration system and further cause bad influences on units’ stable operation. Under catalytic cracking reaction conditions, large amount of iron nanonodules is formed on the seriously iron contaminated catalyst due to exothermic reaction. These nodules intensify the attrition between catalyst particles and generate plenty of fines which severely influence units’ smooth running. A dense layer could be formed on the catalysts’ surface after iron contamination and the dense layer stops reactants to diffuse to inner structures of catalyst. This causes extremely negative effects on catalyst’s heavy oil conversion ability and could greatly cut down gasoline yield while increasing yields of dry gas, coke, and slurry largely. Research shows that catalyst’s reaction performance would be severely deteriorated when iron content in E-cat (equilibrium catalyst exceeds 8000 μg/g.

Design and performance studies of a hadronic calorimeter for a FCC-hh experiment

Science.gov (United States)

Faltova, J.

2018-03-01

The hadron-hadron Future Circular Collider (FCC-hh) project studies the physics reach of a proton-proton machine with a centre-of-mass-energy of 100 TeV and five times greater peak luminosities than at the High-Luminosity LHC (HL-LHC). The high-energy regime of the FCC-hh opens new opportunities for the discovery of physics beyond the standard model. At 100 TeV a large fraction of the W, Z, H bosons and top quarks are produced with a significant boost. It implies an efficient reconstruction of very high energetic objects decaying hadronically. The reconstruction of those boosted objects sets the calorimeter performance requirements in terms of energy resolution, containment of highly energetic hadron showers, and high transverse granularity. We present the current baseline technologies for the calorimeter system in the barrel region of the FCC-hh reference detector: a liquid argon electromagnetic and a scintillator-steel hadronic calorimeters. The focus of this paper is on the hadronic calorimeter and the performance studies for hadrons. The reconstruction of single particles and the achieved energy resolution for the combined system of the electromagnetic and hadronic calorimeters are discussed.

FCC046: A CANDIDATE GASEOUS POLAR RING DWARF ELLIPTICAL GALAXY IN THE FORNAX CLUSTER

Energy Technology Data Exchange (ETDEWEB)

De Rijcke, S.; Buyle, P.; Koleva, M. [Department of Physics and Astronomy, Ghent University, Krijgslaan 281 S9, B-9000 Ghent (Belgium)

2013-06-20

FCC046 is a Fornax Cluster dwarf elliptical galaxy. Optical observations have shown that this galaxy, besides an old and metal-poor stellar population, also contains a very young centrally concentrated population and is actively forming stars, albeit at a very low level. Here, we report on 21 cm observations of FCC046 with the Australia Telescope Compact Array which we conducted in the course of a small survey of Fornax Cluster early-type dwarf galaxies. We have discovered a {approx}10{sup 7} M{sub Sun} H I cloud surrounding FCC046. We show that the presence of this significant gas reservoir offers a concise explanation for this galaxy's optical morphological and kinematical properties. Surprisingly, the H I gas, as evidenced by its morphology and its rotational motion around the galaxy's optical major axis, is kinematically decoupled from the galaxy's stellar body. This is the first time such a ring of gaseous material in minor-axis rotation is discovered around a dwarf galaxy.

Hydrothermal synthesis of highly crystalline RuS2 nanoparticles as cathodic catalysts in the methanol fuel cell and hydrochloric acid electrolysis

International Nuclear Information System (INIS)

Li, Yanjuan; Li, Nan; Yanagisawa, Kazumichi; Li, Xiaotian; Yan, Xiao

2015-01-01

Highlights: • Highly crystalline RuS 2 nanoparticles have been first synthesized by a “one-step” hydrothermal method. • The product presents a pure cubic phase of stoichiometric ratio RuS 2 with average particle size of 14.8 nm. • RuS 2 nanoparticles were used as cathodic catalysts in methanol fuel cell and hydrochloric acid electrolysis. • The catalyst outperforms commercial Pt/C in methanol tolerance and stability towards Cl − . - Abstract: Highly crystalline ruthenium sulfide (RuS 2 ) nanoparticles have been first synthesized by a “one-step” hydrothermal method at 400 °C, using ruthenium chloride and thiourea as reactants. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy/energy disperse spectroscopy (SEM/EDS), thermo gravimetric-differential thermal analyze (TG-DTA), transmission electron microscopy equipped with selected area electron diffraction (TEM/SAED). Fourier transform infrared spectra (IR), and X-ray photoelectron spectroscopy (XPS). XRD result illustrates that the highly crystalline product presents a pure cubic phase of stoichiometric ratio RuS 2 and the average particle size is 14.8 nm. SEM and TEM images display the products have irregular shape of 6–25 nm. XPS analyst indicates that the sulfur exists in the form of S 2 2− . Cyclic voltammetry (CV), rotating disk electrode (RDE), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) measurements are conducted to evaluate the electrocatalytic activity and stability of the highly crystalline RuS 2 nanoparticles in oxygen reduction reaction (ORR) for methanol fuel cell and hydrochloric acid electrolysis. The results illustrate that RuS 2 is active towards oxygen reduction reaction. Although the activity of RuS 2 is lower than that of Pt/C, the RuS 2 catalyst outperforms commercial Pt/C in methanol tolerance and stability towards Cl −

High rate flame synthesis of highly crystalline iron oxide nanorods

International Nuclear Information System (INIS)

Merchan-Merchan, W; Taylor, A M; Saveliev, A V

2008-01-01

Single-step flame synthesis of iron oxide nanorods is performed using iron probes inserted into an opposed-flow methane oxy-flame. The high temperature reacting environment of the flame tends to convert elemental iron into a high density layer of iron oxide nanorods. The diameters of the iron oxide nanorods vary from 10 to 100 nm with a typical length of a few microns. The structural characterization performed shows that nanorods possess a highly ordered crystalline structure with parameters corresponding to cubic magnetite (Fe 3 O 4 ) with the [100] direction oriented along the nanorod axis. Structural variations of straight nanorods such as bends, and T-branched and Y-branched shapes are frequently observed within the nanomaterials formed, opening pathways for synthesis of multidimensional, interconnected networks

A Note on Cubic Convolution Interpolation

OpenAIRE

Meijering, E.; Unser, M.

2003-01-01

We establish a link between classical osculatory interpolation and modern convolution-based interpolation and use it to show that two well-known cubic convolution schemes are formally equivalent to two osculatory interpolation schemes proposed in the actuarial literature about a century ago. We also discuss computational differences and give examples of other cubic interpolation schemes not previously studied in signal and image processing.

Crystalline and Crystalline International Disposal Activities

Energy Technology Data Exchange (ETDEWEB)

Viswanathan, Hari S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffrey De' Haven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-03-06

This report presents the results of work conducted between September 2015 and July 2016 at Los Alamos National Laboratory in the crystalline disposal and crystalline international disposal work packages of the Used Fuel Disposition Campaign (UFDC) for DOE-NE’s Fuel Cycle Research and Development program. Los Alamos focused on two main activities during this period: Discrete fracture network (DFN) modeling to describe flow and radionuclide transport in complex fracture networks that are typical of crystalline rock environments, and a comprehensive interpretation of three different colloid-facilitated radionuclide transport experiments conducted in a fractured granodiorite at the Grimsel Test Site in Switzerland between 2002 and 2013. Chapter 1 presents the results of the DFN work and is divided into three main sections: (1) we show results of our recent study on the correlation between fracture size and fracture transmissivity (2) we present an analysis and visualization prototype using the concept of a flow topology graph for characterization of discrete fracture networks, and (3) we describe the Crystalline International work in support of the Swedish Task Force. Chapter 2 presents interpretation of the colloidfacilitated radionuclide transport experiments in the crystalline rock at the Grimsel Test Site.

Phonons in fcc binary alloys

International Nuclear Information System (INIS)

Sharma, Amita; Rathore, R.P.S.

1992-01-01

Born-Mayer potential has been modified to account for the unpaired (three body) forces among the common nearest neighbours of the ordered binary fcc alloys i.e. Ni 3 Fe 7 , Ni 5 Fe 5 and Ni 75 Fe 25 . The three body potential is added to the two body form of Morse to formalize the total interaction potential. Measured inverse ionic compressibility, cohesive energy, lattice constant and one measured phonon frequency are used to evaluate the defining parameters of the potential. The potential seeks to bring about the binding among 140 and 132 atoms though pair wise (two body) and non-pair wise (three body) forces respectively. The phonon-dispersion relations obtained by solving the secular equation are compared with the experimental findings on the aforesaid alloys. (author). 19 refs., 3 figs

Drug Release and Skin Permeation from Lipid Liquid Crystalline Phases

Science.gov (United States)

Costa-Balogh, F. O.; Sparr, E.; Sousa, J. J. S.; Pais, A. A. C. C.

We have studied drug release and skin permeation from several different liquid crystalline lipid formulations that may be used to control the respective release rates. We have studied the release and permeation through human skin of a water-soluble and amphiphilic drug, propranolol hydrochloride, from several formulations prepared with monoolein and phytantriol as permeation enhancers and controlled release excipients. Diolein and cineol were added to selected formulations. We observed that viscosity decreases with drug load, wich is compatible with the occurrence of phase changes. Diolein stabilizes the bicontinuous cubic phases leading to an increase in viscosity and sustained release of the drug. The slowest release was found for the cubic phases with higher viscosity. Studies on skin permeation showed that these latter formulations also presented lower permeability than the less viscous monoolein lamellar phases. Formulations containing cineol originated higher permeability with higher enhancement ratios. Thus, the various formulations are adapted to different circumstances and delivery routes. While a slow release is usually desired for drug sustained delivery, the transdermal route may require a faster release. Lamellar phases, which are less viscous, are more adapted to transdermal applications. Thus, systems involving lamellar phases of monoolein and cineol are good candidates to be used as skin permeation enhancers for propranolol hydrochloride.

Pattern formation in three-dimensional reaction-diffusion systems

Science.gov (United States)

Callahan, T. K.; Knobloch, E.

1999-08-01

Existing group theoretic analysis of pattern formation in three dimensions [T.K. Callahan, E. Knobloch, Symmetry-breaking bifurcations on cubic lattices, Nonlinearity 10 (1997) 1179-1216] is used to make specific predictions about the formation of three-dimensional patterns in two models of the Turing instability, the Brusselator model and the Lengyel-Epstein model. Spatially periodic patterns having the periodicity of the simple cubic (SC), face-centered cubic (FCC) or body-centered cubic (BCC) lattices are considered. An efficient center manifold reduction is described and used to identify parameter regimes permitting stable lamellæ, SC, FCC, double-diamond, hexagonal prism, BCC and BCCI states. Both models possess a special wavenumber k* at which the normal form coefficients take on fixed model-independent ratios and both are described by identical bifurcation diagrams. This property is generic for two-species chemical reaction-diffusion models with a single activator and inhibitor.

Phase transition and mechanical properties of tungsten nanomaterials from molecular dynamic simulation

Energy Technology Data Exchange (ETDEWEB)

Chen, L.; Fan, J. L.; Gong, H. R., E-mail: gonghr@csu.edu.cn [Central South University, State Key Laboratory of Powder Metallurgy (China)

2017-03-15

Molecular dynamic simulation is used to systematically find out the effects of the size and shape of nanoparticles on phase transition and mechanical properties of W nanomaterials. It is revealed that the body-centered cubic (BCC) to face-centered cubic (FCC) phase transition could only happen in cubic nanoparticles of W, instead of the shapes of sphere, octahedron, and rhombic dodecahedron, and that the critical number to trigger the phase transition is 5374 atoms. Simulation also shows that the FCC nanocrystalline W should be prevented due to its much lower tensile strength than its BCC counterpart and that the octahedral and rhombic dodecahedral nanoparticles of W, rather than the cubic nanoparticles, should be preferred in terms of phase transition and mechanical properties. The derived results are discussed extensively through comparing with available observations in the literature to provide a deep understanding of W nanomaterials.

Effect of ZSM-5 on the production of reformulated gasoline. Comparison between FCC pilot plant and commercial results

International Nuclear Information System (INIS)

Lappas, A.A.; Iatridis, D.; Vasalos, I.A.; Phyxogios, G.

1999-01-01

One of the more interesting ways for production of light olefins and for minimization of Gasoline olefins is the use of catalytic additives in the FCC (fluid catalytic cracking) inventory. The most widely used additive for the FCC process is the ZSM-5 which is a shape selective zeolite. When this additive is added to FCC units, it boosts the yields of LPG's olefins at the expense of gasoline, while increasing gasoline RON. The addition of ZSM-5 offers a great flexibility to a refinery since, in a relatively simple and cheap way, it can increase the RON and produces higher yields of light olefins. For all the above reasons the last years more studies are carried out in order to investigate the effect of this additive. In study presented in this paper, main emphasis was given, for the investigation of the effect of ZSM- 5 addition on FCC product distribution and especially on gasoline olefins. Moreover, in the previous literature works the ZSM-5 influences were examined using mainly fixed bed reactors. In the present study the investigation was carried out in a FCC pilot plant. The additive was also added in a commercial FCC unit of a Greek refinery (Hellenic Aspropyrgos Refinery - HAR) and thus comparison results of commercial and pilot plant test are also presented. The above study is part of a research collaboration which exists the last 10 years between the laboratory of Environmental Fuels and hydrocarbons of Chemical Process Engineering Research Institute (LEFH/CPERI) and the main Greek refineries (HEL.PETROLEUM, Motor Oil Hellas Refinery). The target of this research collaboration is i) the development of technology for the production of reformulated fuels and hydrocarbons and ii) to assist the Greek refineries to face the new regulations for environmental friendly fuels

Fabrication, morphological, structural and magnetic properties of electrodeposited Fe{sub 3}Pt nanowires and nanotubes

Energy Technology Data Exchange (ETDEWEB)

Khan, U. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Adeela, N. [Centre for High Energy Physics, University of the Punjab, Lahore 54000 (Pakistan); Li, Wenjing; Irfan, M.; Javed, K.; Riaz, S. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Han, X.F., E-mail: xfhan@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2017-02-15

Highly ordered Fe{sub 3}Pt nanowires (NWs) and nanotubes (NTs) embedded in anodic aluminum oxide (AAO) template have been fabricated by dc electrodeposition method. Response of heat treatment on structural and magnetic properties of the samples has been studied with and without the presence of magnetic field (1 T). X-Ray Diffraction analysis shows chemically ordered L1{sub 2} face centered cubic (FCC) as the dominant phase for Fe{sub 3}Pt NWs and heat treatment improves crystallinity with retained its phase. Whereas, Fe{sub 3}Pt NTs show amorphous behavior with and without magnetic field annealing. Furthermore, magnetic properties of the samples have been investigated by vibrating sample magnetometer (VSM). Magnetic parameters of Fe{sub 3}Pt including magnetic coercivity, saturation magnetization, squareness and shape of MH-loops have been investigated as a result of simple and MF annealing. - Highlights: • Fe{sub 3}Pt NWs and NTs embedded into anodic alumina templates have been synthesized by dc electrodeposition method. • Structural analysis (XRD) confirmed the formation of fcc structure. • Magnetic properties have been measured as a function of simple and magnetic field annealing.

Anti-Invar properties and magnetic order in fcc Fe-Ni-C alloy

International Nuclear Information System (INIS)

Nadutov, V.M.; Kosintsev, S.G.; Svystunov, Ye.O.; Garamus, V.M.; Willumeit, R.; Eckerlebe, H.; Ericsson, T.; Annersten, H.

2011-01-01

Anti-Invar effect was revealed in the fcc Fe-25.3%Ni-0.73%C (wt%) alloy, which demonstrates high values of thermal expansion coefficient (TEC) (15-21)x10 -6 K -1 accompanied by almost temperature-insensitive behavior in temperature range of 122-525 K. Alloying with carbon considerably expanded the low temperature range of anti-Invar behavior in fcc Fe-Ni-based alloy. The Curie temperature of the alloy T C =195 K was determined on measurements of temperature dependences of magnetic susceptibility and saturation magnetization. The Moessbauer and small-angle neutron scattering (SANS) experiments on the fcc Fe-25.3%Ni-(0.73-0.78)%C alloys with the varying temperatures below and above the Curie point and in external magnetic field of 1.5-5 T were conducted. Low value of the Debye temperature Θ D =180 K was estimated using the temperature dependence of the integral intensity of Moessbauer spectra for specified temperature range. The inequality B eff =(0.7-0.9)B ext was obtained in external field Moessbauer measurement that points to antiferromagnetically coupled Fe atoms, which have a tendency to align their spins perpendicular to B ext . Nano length scale magnetic inhomogeneities nearby and far above T C were revealed, which assumed that it is caused by mixed antiferromagnetically and ferromagnetically coupled Fe atom spins. The anti-Invar behavior of Fe-Ni-C alloy is explained in terms of evolution of magnetic order with changing temperature resulting from thermally varied interspin interaction and decreasing stiffness of interatomic bond. - Highlights: → Anti-Invar effect was revealed in the fcc Fe-25.3%Ni-0.73%C (wt%) alloy. → Carbon expanded the temperature range of anti-Invar behavior in Fe-Ni-based alloy. → Moessbauer data point to mixed interspin interaction and low the Dedye temperature. → The SANS experiments reveal nano length scale magnetic inhomogeneities ≤6 nm. → Anti-Invar behavior of Fe-Ni-C alloy explained by thermally varied magnetic order.

Two-Layer 16 Tesla Cosθ Dipole Design for the FCC

Energy Technology Data Exchange (ETDEWEB)

Holik, Eddie Frank [Fermilab; Ambrosio, Giorgio [Fermilab; Apollinari, G. [Fermilab

2018-02-13

The Future Circular Collider or FCC is a study aimed at exploring the possibility to reach 100 TeV total collision energy which would require 16 tesla dipoles. Upon the conclusion of the High Luminosity Upgrade, the US LHC Accelerator Upgrade Pro-ject in collaboration with CERN will have extensive Nb3Sn magnet fabrication experience. This experience includes robust Nb3Sn conductor and insulation scheming, 2-layer cos2θ coil fabrication, and bladder-and-key structure and assembly. By making im-provements and modification to existing technology the feasibility of a two-layer 16 tesla dipole is investigated. Preliminary designs indicate that fields up to 16.6 tesla are feasible with conductor grading while satisfying the HE-LHC and FCC specifications. Key challenges include accommodating high-aspect ratio conductor, narrow wedge design, Nb3Sn conductor grading, and especially quench protection of a 16 tesla device.

Magnetization, Magnetocrystalline Anisotropy and the Crystalline Electric Field in Rare-Earth Al2 Compounds

DEFF Research Database (Denmark)

Purwins, H. -G.; Walker, E.; Barbara, B.

1974-01-01

a quantitative quantum mechanical description of the magnetization and the related magnetocrystalline anisotropy in terms of a cubic crystalline electric field and an isotropic exchange interaction. The parameters used in this description can be unified to good approximation to all REAl2 intermetallic compounds......Magnetization measurements are reported for single crystals of PrAl2 in the range from 4.2K to 30K for magnetic fields up to 150 kOe applied in the (100), (110) and (111) directions. For these measurements, together with the magnetization results obtained earlier for TbAl2 the authors give...

On q-power cycles in cubic graphs

DEFF Research Database (Denmark)

Bensmail, Julien

2017-01-01

In the context of a conjecture of Erdos and Gyárfás, we consider, for any q ≥ 2, the existence of q-power cycles (i.e. with length a power of q) in cubic graphs. We exhibit constructions showing that, for every q ≥ 3, there exist arbitrarily large cubic graphs with no q-power cycles. Concerning...... the remaining case q = 2 (which corresponds to the conjecture of Erdos and Gyárfás), we show that there exist arbitrarily large cubic graphs whose only 2-power cycles have length 4 only, or 8 only....

Mesostructured germanium with cubic pore symmetry

Energy Technology Data Exchange (ETDEWEB)

Armatas, G S; Kanatzidis, M G [Michigan State Univ., Michigan (United States), Dept. of Chemistry

2006-11-15

Regular mesoporous oxide materials have been widely studied and have a range of potential applications, such as catalysis, absorption and separation. They are not generally considered for their optical and electronic properties. Elemental semiconductors with nanopores running through them represent a different form of framework material with physical characteristics contrasting with those of the more conventional bulk, thin film and nanocrystalline forms. Here we describe cubic meso structured germanium, MSU-Ge-l, with gyroidal channels containing surfactant molecules, separated by amorphous walls that lie on the gyroid (G) minimal surface as in the mesoporous silica MCM-48. Although Ge is a high-meltin covalent semiconductor that is difficult to prepare from solution polymerization, we succeeded in assembling a continuous Ge network using a suitable precursor for Ge{sup 4-} atoms. Our results indicate that elemental semiconductors from group 14 of the periodic table can be made to adopt meso structured forms such as MSU-Ge-1, which features two three-dimensional labyrinthine tunnels obeying la3d space group symmetry and separated by a continuous germanium minimal surface that is otherwise amorphous. A consequence of this new structure for germanium, which has walls only one nanometre thick, is a wider electronic energy bandgap (1.4 eV versus 0.66 eV) than has crystalline or amorphous Ge. Controlled oxidation of MSU-Ge-1 creates a range of germanium suboxides with continuously varying Ge:O ratio and a smoothly increasing energy gap. (author)

Properties of heavy alkali metals under pressure

International Nuclear Information System (INIS)

Eremenko, T.M.; Zarochentsev, E.V.

1980-01-01

Zero isotherms, polymorphic phase body-centered cubic (BCC)-faced-centered cubic (FCC) transitions and K, Rb and Cs phonon spectra have been calculated within the framework of a pseudopotential model added with a short-range repulsion of frames in the Born-Mayer form. It is shown that taking into account Esub(SR) zero isotherms and phonon frequencies change insignificantly; microscopic Grueneisen parameters change by 10-20 % and BCC-FCC transition pressure decreases several times. The agreement of theoretic and experimentally observed characteristics of the transition in Cs and K and Rb phonon spectra is quite satisfactory

Dislocation cross-slip in fcc solid solution alloys

International Nuclear Information System (INIS)

Nöhring, Wolfram Georg; Curtin, W.A.

2017-01-01

Cross-slip is a fundamental process of screw dislocation motion and plays an important role in the evolution of work hardening and dislocation structuring in metals. Cross-slip has been widely studied in pure FCC metals but rarely in FCC solid solutions. Here, the cross-slip transition path in solid solutions is calculated using atomistic methods for three representative systems of Ni-Al, Cu-Ni and Al-Mg over a range of solute concentrations. Studies using both true random alloys and their corresponding average-alloy counterparts allow for the independent assessment of the roles of (i) fluctuations in the spatial solute distribution in the true random alloy randomness and (ii) average alloy properties such as stacking fault energy. The results show that the solute fluctuations dominate the activation energy barrier, i.e. there are large sample-to-sample variations around the average activation barrier. The variations in activation barrier correlate linearly with the energy difference between the initial and final states. The distribution of this energy difference can be computed analytically in terms of the solute/dislocation interaction energies. Thus, the distribution of cross-slip activation energies can be accurately determined from a parameter-free analytic model. The implications of the statistical distribution of activation energies on the rate of cross-slip in real alloys are then identified.

High-speed jet electrodeposition and microstructure of nanocrystalline Ni-Co alloys

International Nuclear Information System (INIS)

Qiao Guiying; Jing Tianfu; Wang Nan; Gao Yuwei; Zhao Xin; Zhou Jifeng; Wang Wei

2005-01-01

The jet electrodeposition from watts baths with a device of electrolyte jet was carried out to prepare nano-crystalline cobalt-nickel alloys. The influence of the concentration of Co 2+ ions in the electrolyte and electrolysis parameters, such as the cathodic current density, the temperature as well as the electrolyte jet speed, on the chemistry and microstructure of Ni-Co-deposit alloys were investigated. Experimental results indicated that increasing the Co 2+ ions concentration in the bath, the electrolyte jet speed and decreasing of the cathodic current density and decrease of the electrolyte temperature all results in an increase of cobalt content in the alloy. Detailed microstructure changes upon the changes of alloy composition and experimental conditions were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD results show the Ni-Co solid solution was formed through the jet electrodeposition. Phase constitution of solid solution changes progressively under different electrolyte concentration. Alloys with low Co concentration exhibit single phase of face-centered cubic (fcc) structure; The Co concentration over 60.39 wt.%, the alloys are composed of face-centered cubic (fcc) phase and hexagonal close-packed (hcp) phase. Furthermore, the formation of the nanostructured Ni-Co alloy deposit is investigated. Increasing the Co 2+ ions concentration in the bath, the cathodic current density, the electrolyte temperature and the electrolyte jet speed all result in the finer grains in the deposits. Additives such as saccharin in the electrolyte also favor the formation of the finer grains in the alloy deposits

Dynamic simulation of industrial Fluidized-bed Catalytic Cracking - FCC unit

Energy Technology Data Exchange (ETDEWEB)

Secchi, Argimiro R.; Neumann, Gustavo A.; Trierweiler, Jorge O. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Dept. de Engenharia Quimica]. E-mail: arge@enq.ufrgs.br; gneumann@enq.ufrgs.br; jorge@enq.ufrgs.br; Santos, Marlova G. [PETROBRAS S.A., Canoas, RS (Brazil). Refinaria Alberto Pasqualini]. E-mail: marlova@petrobras.com.br

2000-07-01

In this work a mathematical model for the dynamic simulation of the Fluidized-bed Catalytic Cracking (FCC) Reactor, to be used in the analysis, control, and optimization of this system is developed. Based on the full range of published data in FCC performance and kinetic rates, and adapted to the industrial unit of the PETROBRAS' Alberto Pasqualini Refinery (REFAP), an integrated dynamic model is build up. The model is sufficiently complex to capture the major dynamics effects that occur in this system. The regenerator is modeled as emulsion and bubble phases that exchange mass and heat. The riser is modeled as an adiabatic plug flow reactor. The fluid dynamic is taking into account for the catalyst circulation, and the dynamics of the gas phase and the riser are also considered into the model. The model, represented by a non-linear system of differential-algebraic equations, was written in language C and implemented in MATLAB/SIMULINK. The results are compared with the data obtained from the industrial plant of REFAP. (author)

Crystalline and Crystalline International Disposal Activities

Energy Technology Data Exchange (ETDEWEB)

Viswanathan, Hari S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffrey De' Haven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-12-21

This report presents the results of work conducted between September 2014 and July 2015 at Los Alamos National Laboratory in the crystalline disposal and crystalline international disposal work packages of the Used Fuel Disposition Campaign (UFDC) for DOE-NE’s Fuel Cycle Research and Development program.

Dendronized Metal Nanoparticles-Self-Organizing Building Blocks for the Design of New Functional Materials

Science.gov (United States)

2016-04-01

interparticular spacing..    SAXS  measurements   suggest  that  the  hybrids  organize  in  fcc   cubic  phases  between  room  temperature and ca. 120 to 140°C...between  the  inorganic  cores,  or more  precisely  a  rhombo‐dodecaedral  shape,  in  order  to  pack  efficiently  in  the  fcc   lattice.  This  cubic...identity between the a2D parameter of the cubic sub‐cell  and aH,  measure  on a TEM image showing 2 superimposed hexagonal lattices. Each new layer

Overview of design development of FCC-hh Experimental Interaction Regions

CERN Document Server

AUTHOR|(CDS)2082479; Abelleira, Jose; Cruz Alaniz, Emilia; Van Riesen-Haupt, Leon; Benedikt, Michael; Besana, Maria Ilaria; Buffat, Xavier; Burkhardt, Helmut; Cerutti, Francesco; Langner, Andy Sven; Martin, Roman; Riegler, Werner; Schulte, Daniel; Tomas Garcia, Rogelio; Appleby, Robert Barrie; Rafique, Haroon; Barranco Garcia, Javier; Pieloni, Tatiana; Boscolo, Manuela; Collamati, Francesco; Nevay, Laurence James; Hofer, Michael

2017-01-01

The experimental interaction region (EIR) is one of the key areas that define the performance of the Future Circular Collider. In this overview we will describe the status and the evolution of the design of EIR of FCC-hh, focusing on design of the optics, energy deposition in EIR elements, beam-beam effects and machine detector interface issues.

Size and temperature dependent stability and phase transformation in single-crystal zirconium nanowire

International Nuclear Information System (INIS)

Sutrakar, Vijay Kumar; Roy Mahapatra, D.

2011-01-01

A novel size dependent FCC (face-centered-cubic) → HCP (hexagonally-closed-pack) phase transformation and stability of an initial FCC zirconium nanowire are studied. FCC zirconium nanowires with cross-sectional dimensions 20 Å, in which surface stresses are not enough to drive the phase transformation, show meta-stability. In such a case, an external kinetic energy in the form of thermal heating is required to overcome the energy barrier and achieve FCC → HCP phase transformation. The FCC-HCP transition pathway is also studied using Nudged Elastic Band (NEB) method, to further confirm the size dependent stability/metastability of Zr nanowires. We also show size dependent critical temperature, which is required for complete phase transformation of a metastable-FCC nanowire.

Electronic band structure and optical properties of the cubic, Sc, Y and La hydride systems

International Nuclear Information System (INIS)

Peterman, D.J.

1980-01-01

Electronic band structure calculations are used to interpret the optical spectra of the cubic Sc, Y and La hydride systems. Self-consistent band calculations of ScH 2 and YH 2 were carried out. The respective joint densities of states are computed and compared to the dielectric functions determined from the optical measurements. Additional calculations were performed in which the Fermi level or band gap energies are rigidly shifted by a small energy increment. These calculations are then used to simulate the derivative structure in thermomodulation spectra and relate the origin of experimental interband features to the calculated energy bands. While good systematic agreement is obtained for several spectral features, the origin of low-energy interband transitions in YH 2 cannot be explained by these calculated bands. A lattice-size-dependent premature occupation of octahedral sites by hydrogen atoms in the fcc metal lattice is suggested to account for this discrepancy. Various non-self-consistent calculations are used to examine the effect of such a premature occupation. Measurements of the optical absorptivity of LaH/sub x/ with 1.6 2 lattice. These experimental results also suggest that, in contrast to recent calculations, LaH 3 is a small-band-gap semiconductor

Future Circular Collider Study (FCC) kick-off meeting | 12-15 February

CERN Multimedia

2014-01-01

The kick-off meeting of the international "Future Circular Collider Study" (FCC) will take place in Geneva from 12 to 15 February 2014 at the University of Geneva, Unimail site. The programme and registration details can be found on the meeting's website. This meeting is the starting point of the five-year international "Future Circular Collider Study" (FCC). The main emphasis of the conceptual design study will be on a hadron collider with a centre-of-mass energy of the order of 100 TeV in a new tunnel with a 80-100 km circumference for the purposes of studying physics at the highest energies. The study will also include a lepton collider, as a potential intermediate step towards realisation of the hadron facility. Options for e-p scenarios will also be considered. The main purpose of this meeting is to discuss the study topics and to prepare international collaborations. The meeting is a public meeting with a registration deadline closing on Friday 31 Janua...

Description of hardening curves of fcc single- and polycrystals

International Nuclear Information System (INIS)

Mecking, H.

1975-01-01

Stress-strain curves are analyzed over their entire strain region and over a wide range of temperatures to arrive at a general analytic description of work-hardening curves. The data were obtained with fcc single and polycrystals, but there is experimental and theoretical evidence that the principles of the analysis are also applicable for other crystal structures and even for more complex technical materials. 9 figs, 1 table, 46 refs

Three-dimensional Random Voronoi Tessellations: From Cubic Crystal Lattices to Poisson Point Processes

OpenAIRE

Lucarini, Valerio

2008-01-01

We perturb the SC, BCC, and FCC crystal structures with a spatial Gaussian noise whose adimensional strength is controlled by the parameter a, and analyze the topological and metrical properties of the resulting Voronoi Tessellations (VT). The topological properties of the VT of the SC and FCC crystals are unstable with respect to the introduction of noise, because the corresponding polyhedra are geometrically degenerate, whereas the tessellation of the BCC crystal is topologically stable eve...

Crystal phase-based epitaxial growth of hybrid noble metal nanostructures on 4H/fcc Au nanowires

Science.gov (United States)

Lu, Qipeng; Wang, An-Liang; Gong, Yue; Hao, Wei; Cheng, Hongfei; Chen, Junze; Li, Bing; Yang, Nailiang; Niu, Wenxin; Wang, Jie; Yu, Yifu; Zhang, Xiao; Chen, Ye; Fan, Zhanxi; Wu, Xue-Jun; Chen, Jinping; Luo, Jun; Li, Shuzhou; Gu, Lin; Zhang, Hua

2018-03-01

Crystal-phase engineering offers opportunities for the rational design and synthesis of noble metal nanomaterials with unusual crystal phases that normally do not exist in bulk materials. However, it remains a challenge to use these materials as seeds to construct heterometallic nanostructures with desired crystal phases and morphologies for promising applications such as catalysis. Here, we report a strategy for the synthesis of binary and ternary hybrid noble metal nanostructures. Our synthesized crystal-phase heterostructured 4H/fcc Au nanowires enable the epitaxial growth of Ru nanorods on the 4H phase and fcc-twin boundary in Au nanowires, resulting in hybrid Au-Ru nanowires. Moreover, the method can be extended to the epitaxial growth of Rh, Ru-Rh and Ru-Pt nanorods on the 4H/fcc Au nanowires to form unique hybrid nanowires. Importantly, the Au-Ru hybrid nanowires with tunable compositions exhibit excellent electrocatalytic performance towards the hydrogen evolution reaction in alkaline media.

Realizing high magnetic moments in fcc Fe nanoparticles through atomic structure stretch

International Nuclear Information System (INIS)

Baker, S H; Roy, M; Thornton, S C; Binns, C

2012-01-01

We describe the realization of a high moment state in fcc Fe nanoparticles through a controlled change in their atomic structure. Embedding Fe nanoparticles in a Cu 1-x Au x matrix causes their atomic structure to switch from bcc to fcc. Extended x-ray absorption fine structure (EXAFS) measurements show that the structure in both the matrix and the Fe nanoparticles expands as the amount of Au in the matrix is increased, with the data indicating a tetragonal stretch in the Fe nanoparticles. The samples were prepared directly from the gas phase by co-deposition, using a gas aggregation source and MBE-type sources respectively for the nanoparticle and matrix materials. The structure change in the Fe nanoparticles is accompanied by a sharp increase in atomic magnetic moment, ultimately to values of ∼2.5 ± 0.3 μ B /atom. (paper)

Shape Preserving Interpolation Using C2 Rational Cubic Spline

Directory of Open Access Journals (Sweden)

Samsul Ariffin Abdul Karim

2016-01-01

Full Text Available This paper discusses the construction of new C2 rational cubic spline interpolant with cubic numerator and quadratic denominator. The idea has been extended to shape preserving interpolation for positive data using the constructed rational cubic spline interpolation. The rational cubic spline has three parameters αi, βi, and γi. The sufficient conditions for the positivity are derived on one parameter γi while the other two parameters αi and βi are free parameters that can be used to change the final shape of the resulting interpolating curves. This will enable the user to produce many varieties of the positive interpolating curves. Cubic spline interpolation with C2 continuity is not able to preserve the shape of the positive data. Notably our scheme is easy to use and does not require knots insertion and C2 continuity can be achieved by solving tridiagonal systems of linear equations for the unknown first derivatives di, i=1,…,n-1. Comparisons with existing schemes also have been done in detail. From all presented numerical results the new C2 rational cubic spline gives very smooth interpolating curves compared to some established rational cubic schemes. An error analysis when the function to be interpolated is ft∈C3t0,tn is also investigated in detail.

Guarded Cubical Type Theory

DEFF Research Database (Denmark)

Birkedal, Lars; Bizjak, Aleš; Clouston, Ranald

2016-01-01

This paper improves the treatment of equality in guarded dependent type theory (GDTT), by combining it with cubical type theory (CTT). GDTT is an extensional type theory with guarded recursive types, which are useful for building models of program logics, and for programming and reasoning...... with coinductive types. We wish to implement GDTT with decidable type-checking, while still supporting non-trivial equality proofs that reason about the extensions of guarded recursive constructions. CTT is a variation of Martin-L\\"of type theory in which the identity type is replaced by abstract paths between...... terms. CTT provides a computational interpretation of functional extensionality, is conjectured to have decidable type checking, and has an implemented type-checker. Our new type theory, called guarded cubical type theory, provides a computational interpretation of extensionality for guarded recursive...

Guarded Cubical Type Theory

DEFF Research Database (Denmark)

Birkedal, Lars; Bizjak, Aleš; Clouston, Ranald

2016-01-01

This paper improves the treatment of equality in guarded dependent type theory (GDTT), by combining it with cubical type theory (CTT). GDTT is an extensional type theory with guarded recursive types, which are useful for building models of program logics, and for programming and reasoning...... with coinductive types. We wish to implement GDTT with decidable type checking, while still supporting non-trivial equality proofs that reason about the extensions of guarded recursive constructions. CTT is a variation of Martin-L\\"of type theory in which the identity type is replaced by abstract paths between...... terms. CTT provides a computational interpretation of functional extensionality, enjoys canonicity for the natural numbers type, and is conjectured to support decidable type-checking. Our new type theory, guarded cubical type theory (GCTT), provides a computational interpretation of extensionality...

Numerically modeling Brownian thermal noise in amorphous and crystalline thin coatings

Science.gov (United States)

Lovelace, Geoffrey; Demos, Nicholas; Khan, Haroon

2018-01-01

Thermal noise is expected to be one of the noise sources limiting the astrophysical reach of Advanced LIGO (once commissioning is complete) and third-generation detectors. Adopting crystalline materials for thin, reflecting mirror coatings, rather than the amorphous coatings used in current-generation detectors, could potentially reduce thermal noise. Understanding and reducing thermal noise requires accurate theoretical models, but modeling thermal noise analytically is especially challenging with crystalline materials. Thermal noise models typically rely on the fluctuation-dissipation theorem, which relates the power spectral density of the thermal noise to an auxiliary elastic problem. In this paper, we present results from a new, open-source tool that numerically solves the auxiliary elastic problem to compute the Brownian thermal noise for both amorphous and crystalline coatings. We employ the open-source deal.ii and PETSc frameworks to solve the auxiliary elastic problem using a finite-element method, adaptive mesh refinement, and parallel processing that enables us to use high resolutions capable of resolving the thin reflective coating. We verify numerical convergence, and by running on up to hundreds of compute cores, we resolve the coating elastic energy in the auxiliary problem to approximately 0.1%. We compare with approximate analytic solutions for amorphous materials, and we verify that our solutions scale as expected with changing beam size, mirror dimensions, and coating thickness. Finally, we model the crystalline coating thermal noise in an experiment reported by Cole et al (2013 Nat. Photon. 7 644–50), comparing our results to a simpler numerical calculation that treats the coating as an ‘effectively amorphous’ material. We find that treating the coating as a cubic crystal instead of as an effectively amorphous material increases the thermal noise by about 3%. Our results are a step toward better understanding and reducing thermal noise to

Study of the physics potential of the FCC-hh machine to measure the coupling of the Higgs boson to b quarks

CERN Document Server

Rodríguez, Arturo

2016-01-01

The FCC project as well as the Pythia + Delphes analysis within the FCC software are introduced. The ROOT analysis carried out to reconstruct main observables, such the invariant mass of the bb system, transverse mass and momentum of the W boson together with the lepton pT and distribution is explained. The resulting reconstructed invariant mass of the bb system showed a peak near the 125 GeV in correspondence with the Higgs boson. Future steps towards estimating the physics potential of the FCC-hh machine in this channel are discussed.

The effect of structural changes during sintering on the electric and magnetic traits of the Ni96.7Mo3.3 alloy nanostructured powder

Directory of Open Access Journals (Sweden)

Ribić-Zelenović L.

2009-01-01

Full Text Available Ni96.7Mo3.3 powder was electrochemically obtained. An X-ray diffraction analysis determined that the powder consisted of a 20% amorphous and 80% crystalline phase. The crystalline phase consisted of a nanocrystalline solid nickel and molybdenum solution with a face-centred cubic (FCC lattice with a high density of chaotically distributed dislocations and high microstrain value. The scanning electronic microscopy (SEM showed that two particle structures were formed: larger cauliflower-like particles and smaller dendriteshaped ones. The thermal stability of the alloy was examined by differential scanning calorimetry (DSC and by measuring the temperature dependence of the electrical resistivity and magnetic permeability. Structural powder relaxation was carried out in the temperature range of 450 K to 560 K causing considerable changes in the electrical resistivity and magnetic permeability. Upon structural relaxation, the magnetic permeability of the cooled alloy was about 80% higher than the magnetic permeability of the fresh powder. The crystallisation of the amorphous portion of the powder and crystalline grain increase occurred in the 630 K to 900 K temperature interval. Upon crystallisation of the amorphous phase and crystalline grain increase, the powder had about 50% lower magnetic permeability than the fresh powder and 3.6 times lower permeability than the powder where only structural relaxation took place.

Randomized Block Cubic Newton Method

KAUST Repository

Doikov, Nikita; Richtarik, Peter

2018-01-01

We study the problem of minimizing the sum of three convex functions: a differentiable, twice-differentiable and a non-smooth term in a high dimensional setting. To this effect we propose and analyze a randomized block cubic Newton (RBCN) method, which in each iteration builds a model of the objective function formed as the sum of the natural models of its three components: a linear model with a quadratic regularizer for the differentiable term, a quadratic model with a cubic regularizer for the twice differentiable term, and perfect (proximal) model for the nonsmooth term. Our method in each iteration minimizes the model over a random subset of blocks of the search variable. RBCN is the first algorithm with these properties, generalizing several existing methods, matching the best known bounds in all special cases. We establish ${\\cal O}(1/\\epsilon)$, ${\\cal O}(1/\\sqrt{\\epsilon})$ and ${\\cal O}(\\log (1/\\epsilon))$ rates under different assumptions on the component functions. Lastly, we show numerically that our method outperforms the state-of-the-art on a variety of machine learning problems, including cubically regularized least-squares, logistic regression with constraints, and Poisson regression.

Randomized Block Cubic Newton Method

KAUST Repository

Doikov, Nikita

2018-02-12

We study the problem of minimizing the sum of three convex functions: a differentiable, twice-differentiable and a non-smooth term in a high dimensional setting. To this effect we propose and analyze a randomized block cubic Newton (RBCN) method, which in each iteration builds a model of the objective function formed as the sum of the natural models of its three components: a linear model with a quadratic regularizer for the differentiable term, a quadratic model with a cubic regularizer for the twice differentiable term, and perfect (proximal) model for the nonsmooth term. Our method in each iteration minimizes the model over a random subset of blocks of the search variable. RBCN is the first algorithm with these properties, generalizing several existing methods, matching the best known bounds in all special cases. We establish ${\\\\cal O}(1/\\\\epsilon)$, ${\\\\cal O}(1/\\\\sqrt{\\\\epsilon})$ and ${\\\\cal O}(\\\\log (1/\\\\epsilon))$ rates under different assumptions on the component functions. Lastly, we show numerically that our method outperforms the state-of-the-art on a variety of machine learning problems, including cubically regularized least-squares, logistic regression with constraints, and Poisson regression.

Comment on 'Magic strains in face-centered and body-centered cubic lattices'

Energy Technology Data Exchange (ETDEWEB)

Waal, B.W. van de (Technische Hogeschool Twente, Enschede (Netherlands). Dept. of Physics)

1990-03-01

The six symmetry-related so-called magic strain tensors that transform a f.c.c. lattice (or a b.c.c. lattice) into itself, which have been reported recently by Boyer are not unique: An infinite number of displacement tensors can be constructed that transform one lattice into another, or into itself. There is no connection with fivefold symmetry, other than that in any f.c.c. crystal. (orig.).

Neutrosophic Cubic MCGDM Method Based on Similarity Measure

Directory of Open Access Journals (Sweden)

Surapati Pramanik

2017-06-01

Full Text Available The notion of neutrosophic cubic set is originated from the hybridization of the concept of neutrosophic set and interval valued neutrosophic set. We define similarity measure for neutrosophic cubic sets and prove some of its basic properties.

47 CFR 0.409 - Commission policy on private printing of FCC forms.

Science.gov (United States)

2010-10-01

... ORGANIZATION General Information General § 0.409 Commission policy on private printing of FCC forms. The... in quality to the original document, without change to the page size, image size, configuration of... Managing Director. [53 FR 27861, July 25, 1988] Printed Publications ...

Cubical version of combinatorial differential forms

DEFF Research Database (Denmark)

Kock, Anders

2010-01-01

The theory of combinatorial differential forms is usually presented in simplicial terms. We present here a cubical version; it depends on the possibility of forming affine combinations of mutual neighbour points in a manifold, in the context of synthetic differential geometry.......The theory of combinatorial differential forms is usually presented in simplicial terms. We present here a cubical version; it depends on the possibility of forming affine combinations of mutual neighbour points in a manifold, in the context of synthetic differential geometry....

Low temperature formation of higher-k cubic phase HfO{sub 2} by atomic layer deposition on GeO{sub x}/Ge structures fabricated by in-situ thermal oxidation

Energy Technology Data Exchange (ETDEWEB)

Zhang, R., E-mail: zhang@mosfet.t.u-tokyo.ac.jp [School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Information Science and Electronic Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Huang, P.-C.; Taoka, N.; Yokoyama, M.; Takenaka, M.; Takagi, S. [School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)

2016-02-01

We have demonstrated a low temperature formation (300 °C) of higher-k HfO{sub 2} using atomic layer deposition (ALD) on an in-situ thermal oxidation GeO{sub x} interfacial layer. It is found that the cubic phase is dominant in the HfO{sub 2} film with an epitaxial-like growth behavior. The maximum permittivity of 42 is obtained for an ALD HfO{sub 2} film on a 1-nm-thick GeO{sub x} form by the in-situ thermal oxidation. It is suggested from physical analyses that the crystallization of cubic phase HfO{sub 2} can be induced by the formation of six-fold crystalline GeO{sub x} structures in the underlying GeO{sub x} interfacial layer.

Crystalline Silica Primer

Science.gov (United States)

,

1992-01-01

Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated

Tuning Eu"3"+ emission in europium sesquioxide films by changing the crystalline phase

International Nuclear Information System (INIS)

Mariscal, A.; Quesada, A.; Camps, I.; Palomares, F.J.; Fernández, J.F.; Serna, R.

2016-01-01

Highlights: • PLD production of high quality europium sesquioxide (Eu_2O_3) films. • The deposition of Al_2O_3 capping and/or buffer layers modifies the crystallization for Eu_2O_3 films upon annealing. • The formation of cubic or monoclinic phases can be favored. • Eu"3"+ emission tuning is achieved as a consequence of crystal field effects. - Abstract: We report the growth of europium sesquioxide (Eu_2O_3) thin films by pulsed laser deposition (PLD) in vacuum at room temperature from a pure Eu_2O_3 ceramic bulk target. The films were deposited in different configurations formed by adding capping and/or buffer layers of amorphous aluminum oxide (a-Al_2O_3). The optical properties, refractive index and extinction coefficient of the as deposited Eu_2O_3 layers were obtained. X-ray photoelectron spectroscopy (XPS) measurements were done to assess its chemical composition. Post-deposition annealing was performed at 500 °C and 850 °C in air in order to achieve the formation of crystalline films and to accomplish photoluminescence emission. According to the analysis of X-ray diffraction (XRD) spectra, cubic and monoclinic phases were formed. It is found that the relative amount of the phases is related to the different film configurations, showing that the control over the crystallization phase can be realized by adequately designing the structures. All the films showed photoluminescence emission peaks (under excitation at 355 nm) that are attributed to the intra 4f-transitions of Eu"3"+ ions. The emission spectral shape depends on the crystalline phase of the Eu_2O_3 layer. Specifically, changes in the hypersensitive "5D_0 → "7F_2 emission confirm the strong influence of the crystal field effect on the Eu"3"+ energy levels.

Quasi-static crack tip fields in rate-sensitive FCC single crystals

Indian Academy of Sciences (India)

In this work, the effects of loading rate, material rate sensitivity and constraint level on quasi-static crack tip fields in a FCC single crystal are studied. ... Global General Motors R&D, India Science Lab, GM Technical Centre (India), Bangalore 560 066, India; Department of Mechanical Engineering, Indian Institute of Science, ...

Band offset in zinc oxy-sulfide/cubic-tin sulfide interface from X-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sanal, K.C.; Nair, P.K.; Nair, M.T.S., E-mail: mtsn@ier.unam.mx

2017-02-28

Highlights: • Zinc oxy-sulfide thin films, 175–240 nm, deposited by rf-sputtering from targets of ZnO + ZnS. • Oxygen content in thin films is enhanced 3–4 times compared with that in ZnO:ZnS targets. • Thin film ZnO{sub x}S{sub 1−x} with x = 0.88–0.27 and optical band gap 2.8–3.2 eV is suitable for solar cells. • The conduction band offset with SnS of cubic structure studied by XPS are +0.41 to −0.28 eV. - Abstract: Zinc oxy-sulfide, ZnO{sub x}S{sub 1−x}, has been found to provide better band alignment in thin film solar cells of tin sulfide of orthorhombic crystalline structure. Here we examine ZnO{sub x}S{sub 1−x}/SnS-CUB interface, in which the ZnO{sub x}S{sub 1−x} thin film was deposited by radio frequency (rf) magnetron sputtering on SnS thin film of cubic (CUB) crystalline structure with a band gap (E{sub g}) of 1.72 eV, obtained via chemical deposition. X-ray photoelectron spectroscopy provides the valence band maxima of the materials and hence places the conduction band offset of 0.41 eV for SnS-CUB/ZnO{sub 0.27}S{sub 0.73} and −0.28 eV for SnS-CUB/ZnO{sub 0.88}S{sub 0.12} interfaces. Thin films of ZnO{sub x}S{sub 1−x} with 175–240 nm in thickness were deposited from targets prepared with different ZnO to ZnS molar ratios. With the target of molar ratio of 1:13.4, the thin films are of composition ZnO{sub 0.27}S{sub 0.73} with hexagonal crystalline structure and with that of 1:1.7 ratio, it is ZnO{sub 0.88}S{sub 0.12}. The optical band gap of the ZnO{sub x}S{sub 1−x} thin films varies from 2.90 eV to 3.21 eV as the sulfur to zinc ratio in the film increases from 0.12:1 to 0.73:1 as determined from X-ray diffraction patterns. Thus, band offsets sought for absorber materials and zinc oxy-sulfide in solar cells may be achieved through a choice of ZnO:ZnS ratio in the sputtering target.

P-union and P-intersection of neutrosophic cubic sets

OpenAIRE

Florentin Smarandache; Chang Su Kim

2015-01-01

Conditions for the P-intersection and P-intersection of falsity-external (resp. indeterminacy-external and truth-external) neutrosophic cubic sets to be an falsity-external (resp. indeterminacy-external and truth- external) neutrosophic cubic set are provided. Conditions for the P-union and the P-intersection of two truth-external (resp. indeterminacy-external and falsity-external) neutrosophic cubic sets to be a truth-internal (resp. indeterminacy-internal and falsity-internal) neutrosoph...

Synthesis and characterization of branched fcc/hcp ruthenium nanostructures and their catalytic activity in ammonia borane hydrolysis

KAUST Repository

AlYami, Noktan

2018-01-30

Several systems have shown the ability to stabilize uncommon crystal structures during the synthesis of metallic nanoparticles. By tailoring the nanoparticle crystal structure, the physical and chemical properties of the particles can also be controlled. Herein, we first synthesized branched nanoparticles of mixed hcp/fcc ruthenium, which were formed using tungsten carbonyl [W(CO)6] as both a reducing agent and a source of carbon monoxide. The branched particles were formed from multiple particulates off a central core. High-resolution transmission electron microscopy (HRTEM) clearly showed that the branched structures consisted of aligned hcp crystal domains, a mixture of fcc and hcp crystal domains with several defects and misalignments, and particles that contained multiple cores and branches. Branched particles were also formed with molybdenum carbonyl [Mo(CO)6], and faceted particles of hcp and fcc particles were formed with Re2(CO)10 as a carbon monoxide source. Without metal carbonyls, small particles of spherical hcp ruthenium were produced, and their size could be controlled by the selection of the precursor. The ruthenium nanoparticles were tested for ammonia borane hydrolysis; the branched nanoparticles were more reactive for catalytic hydrogen evolution than the faceted hcp/fcc nanoparticles or the spherical hcp nanoparticles. This work showcases the potential of crystal phase engineering of transition metal nanoparticles by different carbon monoxide precursors for tailoring their catalytic reactivity.

Temperature dependence of the mechanical properties of equiatomic solid solution alloys with face-centered cubic crystal structures

International Nuclear Information System (INIS)

Wu, Z.; Bei, H.; Pharr, G.M.; George, E.P.

2014-01-01

Compared to decades-old theories of strengthening in dilute solid solutions, the mechanical behavior of concentrated solid solutions is relatively poorly understood. A special subset of these materials includes alloys in which the constituent elements are present in equal atomic proportions, including the high-entropy alloys of recent interest. A unique characteristic of equiatomic alloys is the absence of “solvent” and “solute” atoms, resulting in a breakdown of the textbook picture of dislocations moving through a solvent lattice and encountering discrete solute obstacles. To clarify the mechanical behavior of this interesting new class of materials, we investigate here a family of equiatomic binary, ternary and quaternary alloys based on the elements Fe, Ni, Co, Cr and Mn that were previously shown to be single-phase face-centered cubic (fcc) solid solutions. The alloys were arc-melted, drop-cast, homogenized, cold-rolled and recrystallized to produce equiaxed microstructures with comparable grain sizes. Tensile tests were performed at an engineering strain rate of 10 −3 s −1 at temperatures in the range 77–673 K. Unalloyed fcc Ni was processed similarly and tested for comparison. The flow stresses depend to varying degrees on temperature, with some (e.g. NiCoCr, NiCoCrMn and FeNiCoCr) exhibiting yield and ultimate strengths that increase strongly with decreasing temperature, while others (e.g. NiCo and Ni) exhibit very weak temperature dependencies. To better understand this behavior, the temperature dependencies of the yield strength and strain hardening were analyzed separately. Lattice friction appears to be the predominant component of the temperature-dependent yield stress, possibly because the Peierls barrier height decreases with increasing temperature due to a thermally induced increase of dislocation width. In the early stages of plastic flow (5–13% strain, depending on material), the temperature dependence of strain hardening is due

Effect of orientation and loading rate on compression behavior of small-scale Mo pillars

International Nuclear Information System (INIS)

Schneider, A.S.; Clark, B.G.; Frick, C.P.; Gruber, P.A.; Arzt, E.

2009-01-01

Recently, much work has focused on the size effect in face centered cubic (fcc) structures, however few pillar studies have focused on body centered cubic (bcc) metals. This paper explores the role of bcc crystal structure on the size effect, through compression testing of [001] and [235] Molybdenum (Mo) small-scale pillars manufactured by focused ion beam (FIB). The pillar diameters ranged from 200 nm to 5 μm. Results show that the relationship between yield stress and diameter exhibits an inverse relationship (σ y ∝ d -0.22 for [001] Mo and σ y ∝ d -0.34 for [235] Mo) weaker than that observed for face centered cubic (fcc) metals (σ y ∝ d -0.6to-1.0 ). Additional tests at various loading rates revealed that small-scale Mo pillars exhibit a strain rate sensitivity similar to bulk Mo.

Physics Perspectives for a Future Circular Collider: FCC-ee

CERN Multimedia

CERN. Geneva

2017-01-01

The lectures will briefly discuss the parameters of a Future Circular Collider, before addressing in detail the physics perspectives and the challenges for the experiments and detector systems. The main focus will be on ee and pp collisions, but opportunities for e—p physics will also be covered. The FCC physics perspectives will be presented with reference to the ongoing LHC programme, including the physics potential from future upgrades to the LHC in luminosity and possibly energy.  

First results for a FCC-hh ring optics design

CERN Document Server

Chance, Antoine; Payet, Jacques; Alemany Fernandez, Reyes; Holzer, Bernhard; Schulte, Daniel

2015-01-01

The first order considerations of the optics for the FCC-hh ring are presented. The arc cell is generated taking into account some general considerations like the whole circumference, maximum gradients and lengths of the elements in the cell. The integration of the insertion regions started. Three types of Dispersion Suppressors (DIS) are studied. The sensitivity of the arc parameters to these layout considerations is studied in more detail. An alternative layout is shown as well.

Formation of palladium hydrides in low temperature Ar/H_2-plasma

International Nuclear Information System (INIS)

Wulff, H.; Quaas, M.; Deutsch, H.; Ahrens, H.; Fröhlich, M.; Helm, C.A.

2015-01-01

20 nm thick Pd coatings deposited on Si substrates with 800 nm SiO_2 and 1 nm Cr buffer layers were treated in a 2.45 GHz microwave plasma source at 700 W plasma power and 40 Pa working pressure without substrate heating. For obtaining information on the effect of energy influx due to ion energy on the palladium films the substrate potential was varied from U_s_u_b = 0 V to − 150 V at constant gas flow corresponding to mean ion energies E_i from 0.22 eV ∙ cm"−"2 ∙ s"−"1 to 1.28 eV ∙ cm"−"2 ∙ s"−"1. In contrast to high pressure reactions with metallic Pd, under plasma exposure we do not observe solid solutions over a wide range of hydrogen concentration. The hydrogen incorporation in Pd films takes place discontinuously. At 0 V substrate voltage palladium hydride is formed in two steps to PdH_0_._1_4 and PdH_0_._5_7. At − 50 V substrate voltage PdH_0_._5_7 is formed directly. However, substrate voltages of − 100 V and − 150 V cause shrinking of the unit cell. We postulate the formation of two fcc vacancy palladium hydride clusters PdH_V_a_c(I) and PdH_V_a_c(II). Under longtime plasma exposure the fcc PdH_V_a_c(II) phase forms cubic PdH_1_._3_3. The fcc PdH_0_._5_7 phase decomposes at temperatures > 300 °C to form metallic fcc Pd. The hydrogen removal causes a decrease of lattice defects. In situ high temperature diffractometry measurements also confirm the existence of PdH_V_a_c(II) as a palladium hydride phase. Stoichiometric relationship between cubic PdH_1_._3_3 and fcc PdH_V_a_c(II) becomes evident from XR measurements and structure considerations. We assume both phases have the chemical composition Pd_3H_4. Up to 700 °C we observe phase transformation between both the fcc PdH_V_a_c(II) and cubic PdH_1_._3_3 phases. These phase transformations could be explained analog to a Bain distortion by displacive solid state structural changes. - Highlights: • Thin Pd films were treated under low pressure conditions by an Ar/H_2-plasma. • The

Formation of palladium hydrides in low temperature Ar/H{sub 2}-plasma

Energy Technology Data Exchange (ETDEWEB)

Wulff, H., E-mail: wulff@uni-greifswald.de [University of Greifswald, Institute of Physics, Felix-Hausdorff-Straße 6, 17487 Greifswald (Germany); Quaas, M. [LITEC-LP, Brandteichstraße 20, 17489 Greifswald (Germany); Deutsch, H.; Ahrens, H. [University of Greifswald, Institute of Physics, Felix-Hausdorff-Straße 6, 17487 Greifswald (Germany); Fröhlich, M. [Leibniz Institute for Plasma Science and Technology e.V., Felix-Hausdorff-Straße 2 (Germany); Helm, C.A. [University of Greifswald, Institute of Physics, Felix-Hausdorff-Straße 6, 17487 Greifswald (Germany)

2015-12-01

20 nm thick Pd coatings deposited on Si substrates with 800 nm SiO{sub 2} and 1 nm Cr buffer layers were treated in a 2.45 GHz microwave plasma source at 700 W plasma power and 40 Pa working pressure without substrate heating. For obtaining information on the effect of energy influx due to ion energy on the palladium films the substrate potential was varied from U{sub sub} = 0 V to − 150 V at constant gas flow corresponding to mean ion energies E{sub i} from 0.22 eV ∙ cm{sup −2} ∙ s{sup −1} to 1.28 eV ∙ cm{sup −2} ∙ s{sup −1}. In contrast to high pressure reactions with metallic Pd, under plasma exposure we do not observe solid solutions over a wide range of hydrogen concentration. The hydrogen incorporation in Pd films takes place discontinuously. At 0 V substrate voltage palladium hydride is formed in two steps to PdH{sub 0.14} and PdH{sub 0.57}. At − 50 V substrate voltage PdH{sub 0.57} is formed directly. However, substrate voltages of − 100 V and − 150 V cause shrinking of the unit cell. We postulate the formation of two fcc vacancy palladium hydride clusters PdH{sub Vac}(I) and PdH{sub Vac}(II). Under longtime plasma exposure the fcc PdH{sub Vac}(II) phase forms cubic PdH{sub 1.33}. The fcc PdH{sub 0.57} phase decomposes at temperatures > 300 °C to form metallic fcc Pd. The hydrogen removal causes a decrease of lattice defects. In situ high temperature diffractometry measurements also confirm the existence of PdH{sub Vac}(II) as a palladium hydride phase. Stoichiometric relationship between cubic PdH{sub 1.33} and fcc PdH{sub Vac}(II) becomes evident from XR measurements and structure considerations. We assume both phases have the chemical composition Pd{sub 3}H{sub 4}. Up to 700 °C we observe phase transformation between both the fcc PdH{sub Vac}(II) and cubic PdH{sub 1.33} phases. These phase transformations could be explained analog to a Bain distortion by displacive solid state structural changes. - Highlights: • Thin Pd films

Proceedings, High-Precision $\\alpha_s$ Measurements from LHC to FCC-ee

Energy Technology Data Exchange (ETDEWEB)

d' Enterria, David [CERN; Skands, Peter Z. [Monash U.

2015-01-01

This document provides a writeup of all contributions to the workshop on "High precision measurements of $\\alpha_s$: From LHC to FCC-ee" held at CERN, Oct. 12--13, 2015. The workshop explored in depth the latest developments on the determination of the QCD coupling $\\alpha_s$ from 15 methods where high precision measurements are (or will be) available. Those include low-energy observables: (i) lattice QCD, (ii) pion decay factor, (iii) quarkonia and (iv) $\\tau$ decays, (v) soft parton-to-hadron fragmentation functions, as well as high-energy observables: (vi) global fits of parton distribution functions, (vii) hard parton-to-hadron fragmentation functions, (viii) jets in $e^\\pm$p DIS and $\\gamma$-p photoproduction, (ix) photon structure function in $\\gamma$-$\\gamma$, (x) event shapes and (xi) jet cross sections in $e^+e^-$ collisions, (xii) W boson and (xiii) Z boson decays, and (xiv) jets and (xv) top-quark cross sections in proton-(anti)proton collisions. The current status of the theoretical and experimental uncertainties associated to each extraction method, the improvements expected from LHC data in the coming years, and future perspectives achievable in $e^+e^-$ collisions at the Future Circular Collider (FCC-ee) with $\\cal{O}$(1--100 ab$^{-1}$) integrated luminosities yielding 10$^{12}$ Z bosons and jets, and 10$^{8}$ W bosons and $\\tau$ leptons, are thoroughly reviewed. The current uncertainty of the (preliminary) 2015 strong coupling world-average value, $\\alpha_s(m_Z)$ = 0.1177 $\\pm$ 0.0013, is about 1\\%. Some participants believed this may be reduced by a factor of three in the near future by including novel high-precision observables, although this opinion was not universally shared. At the FCC-ee facility, a factor of ten reduction in the $\\alpha_s$ uncertainty should be possible, mostly thanks to the huge Z and W data samples available.

Resistencia a la corrosión ácida de morteros de cementos adicionados con catalizador de craqueo catalítico gastado (sFCC

Directory of Open Access Journals (Sweden)

Silvia Izquierdo

Full Text Available El catalizador de craqueo catalítico gastado (sFCC es un residuo producido por la industria petroquímica y ha demostrado una elevada potencialidad como adición puzolánica en mezclas de cemento Portland (OPC. El presente artículo evalúa la eficacia del sFCC como adición mineral activa en morteros de cemento Portland, así como la resistencia al ataque químico cuando los materiales producidos son inmersos en ácido sulfúrico (H2SO4, acético (CH3COOH o clorhídrico (HCl. Se llevó a cabo una comparación del desempeño del sFCC como adición frente a adiciones comercialmente disponibles, tales como humo de sílice (SF y metacaolín (MK. Los resultados revelan un incremento en las resistencias mecánicas de hasta un 17% en morteros con sFCC en comparación a un mortero referencia sin adición (OPC. La inmersión en H2SO4 durante 90 días condujo a la formación de yeso y pérdida de resistencias mecánicas de hasta un ~25% en las mezclas con MK y sFCC. Para las muestras inmersas en HCl y especialmente las constituidas con sFCC y MK, se identificó Sal de Friedel, como consecuencia del ingreso de Cl" y posterior reacción con los monosulfoaluminatos formados durante la hidratación del cemento. La inmersión en ácido acético condujo a pérdidas de resistencia de hasta un 57% para OPC y 37% para morteros adicionados con sFCC. De esta manera, la inmersión en HCl promueve el mayor ataque para los sistemas adicionados y posterior deterioro, seguido del CH3COOH y H2SO4. Se destaca el mejor desempeño del mortero con 20% sFCC, en particular en presencia de ácido sulfúrico.

Non-spherical micelles in an oil-in-water cubic phase

DEFF Research Database (Denmark)

Leaver, M.; Rajagopalan, V.; Ulf, O.

2000-01-01

phase, both with and without SDS, was established by NMR self-diffusion. In addition H-2 NMR relaxation experiments have demonstrated that the micelles in the cubic phase are non-spherical, having grown and changed shape upon formation of the cubic phase from the micellar solution. Small angle...... associated with the micellar cubic phase, Pm3n and Fd3m. The micellar volumes calculated for these space groups are similar and are consistent with a change in micellar geometry from spherical to prolate.......The cubic phase formed between the microemulsion and hexagonal phases of the ternary pentaethylene glycol dodecyl ether (C12E5)-decane-water system and that doped with small amounts of sodium dodecylsulfate (SDS) have been investigated. The presence of discrete oil-swollen micelles in the cubic...

Electronic Structure of the fcc Transition Metals Ir, Rh, Pt, and Pd

DEFF Research Database (Denmark)

Andersen, O. Krogh

1970-01-01

We give a complete description of a relativistic augmented-plane-wave calculation of the band structures of the paramagnetic fcc transition metals Ir, Rh, Pt, and Pd. The width and position of the d band decrease in the sequence Ir, Pt, Rh, Pd; and N(EF)=13.8,23.2,18.7, and 32.7 (states/atom)/Ry,......We give a complete description of a relativistic augmented-plane-wave calculation of the band structures of the paramagnetic fcc transition metals Ir, Rh, Pt, and Pd. The width and position of the d band decrease in the sequence Ir, Pt, Rh, Pd; and N(EF)=13.8,23.2,18.7, and 32.7 (states....../atom)/Ry, respectively. Spin-orbit coupling is important for all four metals and the coupling parameter varies by 30% over the d bandwidth. Detailed comparisons with de Haas—van Alphen Fermi-surface dimensions have previously been presented and the agreement was very good. Comparison with measured electronic specific...

Formation of metastable cubic phase in Ce{sub 100−x}Al{sub x} (x=45, 50) alloys and their thermal and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Idzikowski, Bogdan, E-mail: idzi@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Centre for Advanced Materials and Smart Structures, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland); Śniadecki, Zbigniew [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Centre for Advanced Materials and Smart Structures, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland); Puźniak, Roman [Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warszawa (Poland); Kaczorowski, Dariusz [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław (Poland); Centre for Advanced Materials and Smart Structures, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland)

2017-01-01

Ce{sub 100−x}Al{sub x} (x=45 and 50) alloys were synthesized by rapid quenching technique in the form of ribbons composed of nanocrystalline phase of CeAl with the ClCs-type structure (Pm-3m space group) embedded in an amorphous matrix. The cubic CeAl phase is known as metastable with random distribution of Ce and Al atoms in the unit cell. The crystalline volume fraction is about 7.5% in Ce{sub 55}Al{sub 45} and 3% in Ce{sub 50}Al{sub 50}. The alloy Ce{sub 55}Al{sub 45} shows better thermal stability than Ce{sub 50}Al{sub 50}, indicated by higher effective activation energy and higher crystallization temperature. Small off-stoichiometry in Ce{sub 55}Al{sub 45} results in degrading the glass forming ability and promotes formation of the cubic CeAl phase, as confirmed by magnetic measurements. In both alloys, the Ce ions are in stable trivalent state and order magnetically near 20 K. Another magnetic phase transition close to 10 K was found for Ce{sub 50}Al{sub 50} and was attributed to the presence of the well-known stable orthorhombic CeAl phase. To the best of our knowledge, the magnetic behavior of the CeAl cubic phase is reported here for the first time. - Highlights: • Synthesis of metastable cubic CeAl phase by rapid quenching. • The Ce ions in Ce{sub 55}Al{sub 45} and Ce{sub 50}Al{sub 50} are in stable trivalent state. • Magnetic transition near 10 K connected with the orthorhombic CeAl phase. • Phase transition at about 20 K originates from the cubic CeAl phase.

Bifurcation of limit cycles for cubic reversible systems

Directory of Open Access Journals (Sweden)

Yi Shao

2014-04-01

Full Text Available This article is concerned with the bifurcation of limit cycles of a class of cubic reversible system having a center at the origin. We prove that this system has at least four limit cycles produced by the period annulus around the center under cubic perturbations

Ultraboosted Zt and γt production at the HL-LHC and FCC-hh

Energy Technology Data Exchange (ETDEWEB)

Aguilar-Saavedra, J.A. [Universidad de Granada, Departamento de Fisica Teorica y del Cosmos, Granada (Spain)

2017-11-15

Searches for anomalous Zt and γt production provide an excellent probe of flavour-changing top interactions when the energies considered are very large. In this note we estimate the sensitivity to these interactions at the high-luminosity phase of the LHC and a future 100 TeV pp collider (FCC-hh). For the LHC, the expected limits on t → uZ/uγ branching ratios from Zt and γt production will reach the 10{sup -5} level, one order of magnitude better than the existing projections for t → uZ from t anti t production. For the FCC-hh, the limits on t → uZ/uγ could reach an impressive sensitivity at the 10{sup -6} level, with limits on t → cZ/cγ at the 10{sup -5} level. (orig.)

The influence of the surface parameter changes onto the phonon states in ultrathin crystalline films

Science.gov (United States)

Šetrajčić, Jovan P.; Ilić, Dušan I.; Jaćimovski, Stevo K.

2018-04-01

In this paper, we have analytically investigated how the changes in boundary surface parameters influence the phonon dispersion law in ultrathin films of the simple cubic crystalline structure. Spectra of possible phonon states are analyzed using the method of two-time dependent Green's functions and for the diverse combination of boundary surface parameters, this problem was presented numerically and graphically. It turns out that for certain values and combinations of parameters, displacement of dispersion branches outside of bulk zone occurs, leading to the creation of localized phonon states. This fact is of great importance for the heat removal, electrical conductivity and superconducting properties of ultrathin films.

A conceptual solution for a beam halo collimation system for the Future Circular hadron-hadron Collider (FCC-hh)

Science.gov (United States)

Fiascaris, M.; Bruce, R.; Redaelli, S.

2018-06-01

We present the first conceptual solution for a collimation system for the hadron-hadron option of the Future Circular Collider (FCC-hh). The collimation layout is based on the scaling of the present Large Hadron Collider collimation system to the FCC-hh energy and it includes betatron and momentum cleaning, as well as dump protection collimators and collimators in the experimental insertions for protection of the final focus triplet magnets. An aperture model for the FCC-hh is defined and the geometrical acceptance is calculated at injection and collision energy taking into account mechanical and optics imperfections. The performance of the system is then assessed through the analysis of normalized halo distributions and complete loss maps for an ideal lattice. The performance limitations are discussed and a solution to improve the system performance with the addition of dispersion suppression collimators around the betatron cleaning insertion is presented.

Synthesis and characterization of silver-copper core-shell nanoparticles using polyol method for antimicrobial agent

Science.gov (United States)

Hikmah, N.; Idrus, N. F.; Jai, J.; Hadi, A.

2016-06-01

Silver and copper nanoparticles are well-known as the good antimicrobial agent. The nano-size of particles influences in enhancing the antimicrobial activity. This paper discusses the effect of molarity on the microstructure and morphology of silver-copper core-shell nanoparticles prepared by a polyol method. In this study, silver-copper nanoparticles are synthesized through the green approach of polyol method using ethylene glycol (EG) as green solvent and reductant, and polyoxyethylene-(80)-sorbitan monooleate (Tween 80) as a nontoxic stabilizer. The phase and morphology of silver-copper nanoparticles are characterized by X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM) and Transmission electron microscope (TEM). The results XRD confirm the pure crystalline of silver and copper nanoparticles with face-centered cubic (FCC) structure. FESEM and TEM analysis confirm the existence of Ag and Cu nanoparticles in core-shell shape.

Cemento adicionado con un residuo del proceso de craqueo catalítico (FCC: hidratación y microestructura

Directory of Open Access Journals (Sweden)

Silvia Izquierdo

2013-08-01

Full Text Available El presente trabajo estudia el efecto de la incorporación de un residuo procedente de la industria petroquímica denominado catalizador gastado del craqueo catalítico (FCC en la hidratación y microestructura de pastas cementicias. Se utilizan como materiales de referencia, además del cemento portland (OPC, dos tipos de adición de alto desempeño, metacaolín (MK y humo de sílice (HS. La caracterización de los productos de hidratación se realizó por medio de difracción de rayos X (DRX, análisis termogravimétrico (TG, microscopia electrónica de barrido (SEM y resonancia magnética nuclear (NMR. Se complementa este estudio con la evaluación de la resistencia mecánica a compresión de morteros a edad hasta de 90 días. Los resultados indican que los principales productos de hidratación en las pastas adicionadas con FCC son silicato cálcico hidratado (CSH, aluminatos cálcicos hidratados (CAH y silicoaluminatos cálcicos hidratados (CASH. Pastas con 10% de FCC reportan un consumo de cal del 61% a edad de 360 días de curado, valor muy superior al reportado por las adiciones de MK y HS en la misma proporción, esto indica una mayor reactividad del FCC, que incluso se manifiesta a edades tempranas. Cabe anotar que, considerando el factor de dilución, la incorporación de un 10% de FCC como reemplazo del cemento contribuye a la resistencia del material adicionado en órdenes de hasta un 30%. Esto es un indicativo del uso potencial de este residuo como material suplementario en mezclas cementicias.

Crystalline and quasicrystalline allotropes of Pb formed on the fivefold surface of icosahedral Ag-In-Yb

Energy Technology Data Exchange (ETDEWEB)

Sharma, H. R., E-mail: H.R.Sharma@liv.ac.uk; Smerdon, J. A.; Nugent, P. J.; Ribeiro, A.; McGrath, R. [Surface Science Research Centre and Department of Physics, The University of Liverpool, Liverpool L69 3BX (United Kingdom); McLeod, I.; Dhanak, V. R. [Department of Physics and the Stephenson Institute for Renewable Energy, The University of Liverpool, Liverpool L69 3BX (United Kingdom); Shimoda, M. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Tsai, A. P. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

2014-05-07

Crystalline and quasicrystalline allotropes of Pb are formed by evaporation on the fivefold surface of the icosahedral (i) Ag-In-Yb quasicrystal under ultra-high vacuum. Lead grows in three dimensional quasicrystalline order and subsequently forms fivefold-twinned islands with the fcc(111) surface orientation atop of the quasicrystalline Pb. The islands exhibit specific heights (magic heights), possibly due to the confinement of electrons in the islands. We also study the adsorption behavior of C{sub 60} on the two allotropes of Pb. Scanning tunneling microcopy reveals that a high corrugation of the quasicrystalline Pb limits the diffusion of the C{sub 60} molecules and thus produces a disordered film, similar to adsorption behavior of the same molecules on the clean substrate surface. However, the sticking coefficient of C{sub 60} molecules atop the Pb islands approaches zero, regardless of the overall C{sub 60} coverage.

Development of OCDMA system based on Flexible Cross Correlation (FCC) code with OFDM modulation

Science.gov (United States)

Aldhaibani, A. O.; Aljunid, S. A.; Anuar, M. S.; Arief, A. R.; Rashidi, C. B. M.

2015-03-01

The performance of the OCDMA systems is governed by numerous quantitative parameters such as the data rate, simultaneous number of users, the powers of transmitter and receiver, and the type of codes. This paper analyzes the performance of the OCDMA system using OFDM technique to enhance the channel data rate, to save power and increase the number of user of OSCDMA systems compared with previous hybrid subcarrier multiplexing/optical spectrum code division multiplexing (SCM/OSCDM) system. The average received signal to noise ratio (SNR) with the nonlinearity of subcarriers is derived. The theoretical results have been evaluated based on BER and number of users as well as amount of power saved. The proposed system gave better performance and save around -6 dBm of the power as well as increase the number of users twice compare to SCM/OCDMA system. In addition it is robust against interference and much more spectrally efficient than SCM/OCDMA system. The system was designed based on Flexible Cross Correlation (FCC) code which is easier construction, less complexity of encoder/decoder design and flexible in-phase cross-correlation for uncomplicated to implement using Fiber Bragg Gratings (FBGs) for the OCDMA systems for any number of users and weights. The OCDMA-FCC_OFDM improves the number of users (cardinality) 108% compare to SCM/ODCMA-FCC system.

Cubic interactions of Maxwell-like higher spins

Energy Technology Data Exchange (ETDEWEB)

Francia, Dario [Scuola Normale Superiore and INFN,Piazza dei Cavalieri, 7 I-56126 Pisa (Italy); Monaco, Gabriele Lo [Dipartimento di Fisica, Università di Pisa,Piazza Fibonacci, 3, I-56126, Pisa (Italy); Dipartimento di Fisica, Università di Milano-Bicocca,Piazza della Scienza 3, I-20126 Milano (Italy); Mkrtchyan, Karapet [Max Planck Institut für Gravitationsphysik,Am Mühlenberg 1, Potsdam 14476 (Germany)

2017-04-12

We study the cubic vertices for Maxwell-like higher-spins in flat and (A)dS background spaces of any dimension. Reducibility of their free spectra implies that a single cubic vertex involving any three fields subsumes a number of couplings among different particles of various spins. The resulting vertices do not involve traces of the fields and in this sense are simpler than their Fronsdal counterparts. We propose an extension of both the free theory and of its cubic deformation to a more general class of partially reducible systems, that one can obtain from the original theory upon imposing trace constraints of various orders. The key to our results is a version of the Noether procedure allowing to systematically account for the deformations of the transversality conditions to be imposed on the gauge parameters at the free level.

An Abel type cubic system

Directory of Open Access Journals (Sweden)

Gary R. Nicklason

2015-07-01

Full Text Available We consider center conditions for plane polynomial systems of Abel type consisting of a linear center perturbed by the sum of 2 homogeneous polynomials of degrees n and 2n-1 where $n \\ge 2$. Using properties of Abel equations we obtain two general systems valid for arbitrary values on n. For the cubic n=2 systems we find several sets of new center conditions, some of which show that the results in a paper by Hill, Lloyd and Pearson which were conjectured to be complete are in fact not complete. We also present a particular system which appears to be a counterexample to a conjecture by Zoladek et al. regarding rational reversibility in cubic polynomial systems.

Cubication of conservative nonlinear oscillators

International Nuclear Information System (INIS)

Belendez, Augusto; Alvarez, Mariela L; Fernandez, Elena; Pascual, Inmaculada

2009-01-01

A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear and cubic terms depend on the initial amplitude, A, while in a Taylor expansion of the restoring force these coefficients are independent of A. The replacement of the original nonlinear equation by an approximate Duffing equation allows us to obtain an approximate frequency-amplitude relation as a function of the complete elliptic integral of the first kind. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of this scheme.

Hydrothermal synthesis of highly crystalline RuS{sub 2} nanoparticles as cathodic catalysts in the methanol fuel cell and hydrochloric acid electrolysis

Energy Technology Data Exchange (ETDEWEB)

Li, Yanjuan [Key Laboratory of Marine Chemistry Theory and Technology, Minisry of Education Ocean University of China, Qingdao, 266100 (China); College of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Li, Nan, E-mail: lin@jlu.edu.cn [College of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Yanagisawa, Kazumichi [Research Laboratory of Hydrothermal Chemistry, Kochi University, Kochi 780-8520 (Japan); Li, Xiaotian [College of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Yan, Xiao [Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun 130012 (China)

2015-05-15

Highlights: • Highly crystalline RuS{sub 2} nanoparticles have been first synthesized by a “one-step” hydrothermal method. • The product presents a pure cubic phase of stoichiometric ratio RuS{sub 2} with average particle size of 14.8 nm. • RuS{sub 2} nanoparticles were used as cathodic catalysts in methanol fuel cell and hydrochloric acid electrolysis. • The catalyst outperforms commercial Pt/C in methanol tolerance and stability towards Cl{sup −}. - Abstract: Highly crystalline ruthenium sulfide (RuS{sub 2}) nanoparticles have been first synthesized by a “one-step” hydrothermal method at 400 °C, using ruthenium chloride and thiourea as reactants. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy/energy disperse spectroscopy (SEM/EDS), thermo gravimetric-differential thermal analyze (TG-DTA), transmission electron microscopy equipped with selected area electron diffraction (TEM/SAED). Fourier transform infrared spectra (IR), and X-ray photoelectron spectroscopy (XPS). XRD result illustrates that the highly crystalline product presents a pure cubic phase of stoichiometric ratio RuS{sub 2} and the average particle size is 14.8 nm. SEM and TEM images display the products have irregular shape of 6–25 nm. XPS analyst indicates that the sulfur exists in the form of S{sub 2}{sup 2−}. Cyclic voltammetry (CV), rotating disk electrode (RDE), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) measurements are conducted to evaluate the electrocatalytic activity and stability of the highly crystalline RuS{sub 2} nanoparticles in oxygen reduction reaction (ORR) for methanol fuel cell and hydrochloric acid electrolysis. The results illustrate that RuS{sub 2} is active towards oxygen reduction reaction. Although the activity of RuS{sub 2} is lower than that of Pt/C, the RuS{sub 2} catalyst outperforms commercial Pt/C in methanol tolerance and stability towards Cl{sup −}.

Transdermal delivery of paeonol using cubic gel and microemulsion gel

Science.gov (United States)

Luo, Maofu; Shen, Qi; Chen, Jinjin

2011-01-01

Background The aim of this study was to develop new systems for transdermal delivery of paeonol, in particular microemulsion gel and cubic gel formulations. Methods Various microemulsion vehicles were prepared using isopropyl myristate as an oil phase, polyoxyethylated castor oil (Cremophor® EL) as a surfactant, and polyethylene glycol 400 as a cosurfactant. In the optimum microemulsion gel formulation, carbomer 940 was selected as the gel matrix, and consisted of 1% paeonol, 4% isopropyl myristate, 28% Cremophor EL/polyethylene glycol 400 (1:1), and 67% water. The cubic gel was prepared containing 3% paeonol, 30% water, and 67% glyceryl monooleate. Results A skin permeability test using excised rat skins indicated that both the cubic gel and microemulsion gel formulations had higher permeability than did the paeonol solution. An in vivo pharmacokinetic study done in rats showed that the relative bioavailability of the cubic gel and microemulsion gel was enhanced by about 1.51-fold and 1.28-fold, respectively, compared with orally administered paeonol suspension. Conclusion Both the cubic gel and microemulsion gel formulations are promising delivery systems to enhance the skin permeability of paeonol, in particular the cubic gel. PMID:21904450

Kaolin and commercial fcc catalysts in the cracking of loads of polypropylene under refinary conditions

Directory of Open Access Journals (Sweden)

A. M. Ribeiro

2013-12-01

Full Text Available The efficiency of Commercial FCC catalysts (low, medium and high activities was evaluated by the catalytic cracking process of combined feeds of polypropylene (PP and vaseline, using a microactivity test unit (M.A.T. for the production of fuel fractions (gasoline, diesel and residue. The PP/vaseline loads, at 2.0% and 4.0% wt, were processed under refinery conditions (load/catalyst ratio and temperature of process. For the PP/vaseline load (4.0% wt, the production of the gasoline fraction was favored by all catalysts, while the diesel fraction was favored by PP/vaseline load (2.0% wt, showing a preferential contact of the zeolite external surface with the end of the polymer chains for the occurrence of the catalytic cracking. All the loads produced a bigger quantity of the gaseous products in the presence of highly active commercial FCC catalyst. The improvement in the activity of the commercial FCC catalyst decreased the production of the liquid fractions and increased the quantity of the solid fractions, independent of the concentration of the loads. These results can be related to the difficulty of the polymer chains to access the catalyst acid sites, occurring preferentially end-chain scission at the external surface of the catalyst.

Nonlinear dynamics of quadratically cubic systems

International Nuclear Information System (INIS)

Rudenko, O V

2013-01-01

We propose a modified form of the well-known nonlinear dynamic equations with quadratic relations used to model a cubic nonlinearity. We show that such quadratically cubic equations sometimes allow exact solutions and sometimes make the original problem easier to analyze qualitatively. Occasionally, exact solutions provide a useful tool for studying new phenomena. Examples considered include nonlinear ordinary differential equations and Hopf, Burgers, Korteweg–de Vries, and nonlinear Schrödinger partial differential equations. Some problems are solved exactly in the space–time and spectral representations. Unsolved problems potentially solvable by the proposed approach are listed. (methodological notes)

Influences of residual oxygen impurities, cubic indium oxide grains and indium oxy-nitride alloy grains in hexagonal InN crystalline films grown on Si(111) substrates by electron cyclotron resonance plasma-assisted molecular beam epitaxy

International Nuclear Information System (INIS)

Yodo, T.; Nakamura, T.; Kouyama, T.; Harada, Y.

2005-01-01

We investigated the influences of residual oxygen (O) impurities, cubic indium oxide (β-In 2 O 3 ) grains and indium oxy-nitride (InON) alloy grains in 200 nm-thick hexagonal (α)-InN crystalline films grown on Si(111) substrates by electron cyclotron resonance plasma-assisted molecular beam epitaxy. Although β-In 2 O 3 grains with wide band-gap energy were formed in In film by N 2 annealing, they were not easily formed in N 2 -annealed InN films. Even if they were not detected in N 2 -annealed InN films, the as-grown films still contained residual O impurities with concentrations of less than 0.5% ([O]≤0.5%). Although [O]∝1% could be estimated by investigating In 2 O 3 grains formed in N 2 -annealed InN films, [O]≤0.5% could not be measured by it. However, we found that they can be qualitatively measured by investigating In 2 O 3 grains formed by H 2 annealing with higher reactivity with InN and O 2 , using X-ray diffraction and PL spectroscopy. In this paper, we discuss the formation mechanism of InON alloy grains in InN films. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Olefin recovery from FCC off-gas can pay off

International Nuclear Information System (INIS)

Brahn, M.G.

1992-01-01

This paper reports on olefins recovery from refinery FCC offgas streams which offers an attractive cash flow from olefins from a tail-gas stream that has typically been consumed as refinery fuel. Such recovery schemes can be employed in refineries or olefins plants, and can be tailored to fit individual requirements. Mobil Chemical Co. has operated such a dephlegmator-based off-gas recovery unit at its Beaumont, Tex., olefin plant since 1987. It reported that the project was paid out within 11 months of initial start-up

Phase transition and magnetic properties of Mg-doped hexagonal close-packed Ni nanoparticles

International Nuclear Information System (INIS)

Yang Jinghai; Feng Bo; Liu Yang; Zhang Yongjun; Yang Lili; Wang Yaxin; Wei Maobin; Lang Jihui; Wang Dandan; Liu Xiaoyan

2008-01-01

Mg-doped Ni nanoparticles with the hexagonal close-packed (hcp) and face-centered cubic (fcc) structure have been synthesized by sol-gel method sintered at different temperatures in argon atmosphere. The sintering temperature played an important role in the control of the crystalline phase and the particle size. The pure hcp Mg-doped Ni nanoparticles with average particle size of 6.0 nm were obtained at 320 deg. C. The results indicated that the transition from the hcp to the fcc phase occurred in the temperature range between 320 deg. C and 450 deg. C. Moreover, the VSM results showed that the hcp Mg-doped Ni nanoparticles had unique ferromagnetic and superparamagnetic behavior. The unsaturation even at 5000 Oe is one of the superparamagnetic characteristics due to the small particle size. From the ZFC and FC curves, the blocking temperature T B of the hcp sample (6.0 nm) was estimated to be 10 K. The blocking temperature was related to the size of the magnetic particles and the magnetocrystalline anisotropy constant. By theoretical calculation, the deduced particle size was 6.59 nm for hcp Mg-doped Ni nanoparticles which was in agreement with the results of XRD and TEM

On Application of Non-cubic EoS to Compositional Reservoir Simulation

DEFF Research Database (Denmark)

Yan, Wei; Michelsen, Michael Locht; Stenby, Erling Halfdan

Compositional reservoir simulation uses almost exclusively cubic equations of state (EoS) such as the SRK EoS and the PR EoS. This is in contrast with process simulation in the downstream industry where more recent and advanced thermodynamic models are quickly adopted. Many of these models are non-cubic...... EoS, such as the PC-SAFT EoS. A major reason for the use of the conventional cubic EoS in reservoir simulation is the concern over computation time. Flash computation is the most time consuming part in compositional reservoir simulation, and the extra complexity of the non-cubic EoS may significantly...... increase the time consumption. In addition to this, the non-cubic EoS also needs a C7+ characterization. The main advantage of the non-cubic EoS is that it provides for a more accurate descrition of fluid properties, and it is therefore of interest to investigate the computational aspects of using...

Purely cubic action for string field theory

Science.gov (United States)

Horowitz, G. T.; Lykken, J.; Rohm, R.; Strominger, A.

1986-01-01

It is shown that Witten's (1986) open-bosonic-string field-theory action and a closed-string analog can be written as a purely cubic interaction term. The conventional form of the action arises by expansion around particular solutions of the classical equations of motion. The explicit background dependence of the conventional action via the Becchi-Rouet-Stora-Tyutin operator is eliminated in the cubic formulation. A closed-form expression is found for the full nonlinear gauge-transformation law.

Quench Protection Study of the Eurocircol 16 T cosθ Dipole for the Future Circular Collider (FCC)

CERN Document Server

AUTHOR|(CDS)2151660; Caiffi, Barbara; Fabbricatore, Pasquale; Farinon, Stefania; Salmi, Tiina-Mari; Sorbi, Massimo Leone; Stenvall, Antti; Volpini, Giovanni

2017-01-01

After LHC will be turned off, a new, more energetic machine will be needed in order to explore unknown regions of the high-energy physics. For this reason, the project Future Circular Collider (FCC) has started, with the goal of developing a 100 km circumference collider of 50 TeV proton beams. The Eurocircol collaboration is part of the FCC study under the European Community leadership, and it aims to develop a conceptual design of FCC within 2019. One of the main targets is to design a bending dipole able to reach 16 T operation magnetic field, in order to accomplish the size and energy constraints. Such a magnetic field can be reached using Nb$_{3}$Sn conductors at their highest performance. One option under exploration is the Cosθ dipole, by INFN of Milano and Genova. One of the aspects to be taken into consideration is the amount of conductor needed, because of the relatively high cost of superconducting cables involving Nb$_{3}$Sn. The amount of superconductor in the cross-section conductor area is a d...

Tailoring band structure and band filling in a simple cubic (IV, III)-VI superconductor

Science.gov (United States)

Kriener, M.; Kamitani, M.; Koretsune, T.; Arita, R.; Taguchi, Y.; Tokura, Y.

2018-04-01

Superconductivity and its underlying mechanisms are one of the most active research fields in condensed-matter physics. An important question is how to enhance the transition temperature Tc of a superconductor. In this respect, the possibly positive role of valence-skipping elements in the pairing mechanism has been attracting considerable interest. Here we follow this pathway and successfully enhance Tc up to almost 6 K in the simple chalcogenide SnTe known as a topological crystalline insulator by doping the valence-skipping element In substitutionally for the Sn site and codoping Se for the Te site. A high-pressure synthesis method enabled us to form single-phase solid solutions Sn1 -xInxTe1 -ySey over a wide composition range while keeping the cubic structure necessary for the superconductivity. Our experimental results are supported by density-functional theory calculations which suggest that even higher Tc values would be possible if the required doping range was experimentally accessible.

Plastic fluctuations in empty crystals formed by cubic wireframe particles

Science.gov (United States)

McBride, John M.; Avendaño, Carlos

2018-05-01

We present a computer simulation study of the phase behavior of colloidal hard cubic frames, i.e., particles with nonconvex cubic wireframe geometry interacting purely by excluded volume. Despite the propensity of cubic wireframe particles to form cubic phases akin to their convex counterparts, these particles exhibit unusual plastic fluctuations in which a random and dynamic fraction of particles rotate around their lattice positions in the crystal lattice while the remainder of the particles remains fully ordered. We argue that this unexpected effect stems from the nonconvex geometry of the particles in which the faces of a particle can be penetrated by the vertices of the nearest neighbors even at high number densities.

Eliminating cubic terms in the pseudopotential lattice Boltzmann model for multiphase flow

Science.gov (United States)

Huang, Rongzong; Wu, Huiying; Adams, Nikolaus A.

2018-05-01

It is well recognized that there exist additional cubic terms of velocity in the lattice Boltzmann (LB) model based on the standard lattice. In this work, elimination of these cubic terms in the pseudopotential LB model for multiphase flow is investigated, where the force term and density gradient are considered. By retaining high-order (≥3 ) Hermite terms in the equilibrium distribution function and the discrete force term, as well as introducing correction terms in the LB equation, the additional cubic terms of velocity are entirely eliminated. With this technique, the computational simplicity of the pseudopotential LB model is well maintained. Numerical tests, including stationary and moving flat and circular interface problems, are carried out to show the effects of such cubic terms on the simulation of multiphase flow. It is found that the elimination of additional cubic terms is beneficial to reduce the numerical error, especially when the velocity is relatively large. Numerical results also suggest that these cubic terms mainly take effect in the interfacial region and that the density-gradient-related cubic terms are more important than the other cubic terms for multiphase flow.

NCTA v. FCC - Do Commercial Free Speech Justifications Trump Consumers' Personal Data Protection Rights? Answer To Shape Mobile Advertising Industry

DEFF Research Database (Denmark)

Cleff, Evelyne Beatrix; King, Nancy J.

2010-01-01

telecommunication carriers' personal data sharing practices in order to protect their customers' data privacy when the regulation restricts use of the data for marketing purposes. In this case National Cable and Telecommunications Association (NCTA) challenged a new Federal Communications Commission (FCC) rule...... requiring carriers to obtain customers' advance approval before releasing their telephone record information for marketing purposes. NCTA claimed the FCC's new opt-in rule violates companies' First Amendment right to engage in commercial speech. At stake in this appeal was the constitutionally required...... balance between protecting consumers' information privacy in an era of pervasive data processing and protecting the rights of marketers to engage in protected commercial free speech that involves using customers' personal information. A ruling against the FCC would have limited the use of government...

Lattice dynamics of fcc helium at high pressure

International Nuclear Information System (INIS)

Eckert, J.; Thomlinson, W.; Shirane, G.

1977-01-01

The neutron-inelastic-scattering technique was used to measure the phonon dispersion relations in a high-density crystal of fcc He at 38 K. The crystal was grown at a pressure of 4.93 kbar and a temperature of 38.5 K in a high-pressure sample holder. Its lattice parameter was determined to be 3.915 +- 0.002 A, equivalent to a molar volume of 9.03 cm 3 /mol. The measured dispersion curves were found to be in good agreement with a recent calculation by Goldman using the first-order self-consistent phonon theory without short-range correlation functions. The strong anharmonic effects observed in earlier measurements on the crystals of 21 cm 3 /mol were found to be much less prominent in this He crystal. The magnitude of the multiphonon interference effects on the one-phonon intensities is shown to be less than half of that observed in the low-density crystals. Thermodynamic analysis of the data yielded THETA/sup M//sub D/ = 154 K which indicates that the ratio of mean amplitude of vibration to the nearest-neighbor distance is 8.6%, as opposed to nearly 30% for the lowest-density He crystals. The dependence of the phonon energies on volume is discussed with reference to the earlier work of Traylor et al. on an fcc crystal at 11.7 cm 3 /mol. Limited measurements were also made at 22 K to determine the temperature dependence of the phonon energies. Unusually large isochoric temperature shifts of as much as 15% for some phonons close to the zone center were found over the range of 22--38 K

Nature of phase transitions in crystalline and amorphous GeTe-Sb2Te3 phase change materials.

Science.gov (United States)

Kalkan, B; Sen, S; Clark, S M

2011-09-28

The thermodynamic nature of phase stabilities and transformations are investigated in crystalline and amorphous Ge(1)Sb(2)Te(4) (GST124) phase change materials as a function of pressure and temperature using high-resolution synchrotron x-ray diffraction in a diamond anvil cell. The phase transformation sequences upon compression, for cubic and hexagonal GST124 phases are found to be: cubic → amorphous → orthorhombic → bcc and hexagonal → orthorhombic → bcc. The Clapeyron slopes for melting of the hexagonal and bcc phases are negative and positive, respectively, resulting in a pressure dependent minimum in the liquidus. When taken together, the phase equilibria relations are consistent with the presence of polyamorphism in this system with the as-deposited amorphous GST phase being the low entropy low-density amorphous phase and the laser melt-quenched and high-pressure amorphized GST being the high entropy high-density amorphous phase. The metastable phase boundary between these two polyamorphic phases is expected to have a negative Clapeyron slope. © 2011 American Institute of Physics

The FCC-ee Interaction Region Magnet Design

CERN Document Server

Koratzinos, Michael; Blondel, Alain; Bogomyagkov, Anton; Holzer, Bernhard; Oide, Katsunobu; Sinyatkin, Sergey; Zimmermann, Frank; van Nugteren, Jeroen

2016-01-01

The design of the region close to the interaction point of the FCC-ee experiments is especially challenging. The beams collide at an angle (+-15 mrad) in the high-field region of the detector solenoid. Moreover, the very low vertical beta_y* of the machine necessitates that the final focusing quadrupoles have a distance from the IP (L*) of around 2 m and therefore are inside the main detector solenoid. The beams should be screened from the effect of the detector magnetic field, and the emittance blow-up due to vertical dispersion in the interaction region should be minimized, while leaving enough space for detector components. Crosstalk between the two final focus quadrupoles, only about 6 cm apart at the tip, should also be minimized.

Kinks in systems with cubic and quartic anharmonicity

International Nuclear Information System (INIS)

Kashcheev, V.N.

1988-01-01

For a classical system of interacting particles with on-site cubic or quartic anharmonicity explicit analytic solutions of the d'Alembert equation are obtained in the form of kinks in the presence of dissipation (viscous or Rayleigh) and a constant force. These kinks will be asymptotically stable in the case of quartic anharmonicity and unstable in the case cubic anharmonicity

Enhanced propylene production in FCC by novel catalytic materials

Energy Technology Data Exchange (ETDEWEB)

Kelkar, C.P.; Harris, D.; Xu, M.; Fu, J. [BASF Catalyst LLC, Iselin, NJ (United States)

2007-07-01

Fluid catalytic cracking is expected to increasingly supply the additional incremental requirements for propylene. The most efficient route to increase propylene yield from an FCC unit is through the use of medium pore zeolites such as ZSM-5. ZSM-5 zeolite cracks near linear olefins in the gasoline range to LPG olefins such as propylene and butylenes. This paper will describe catalytic approaches to increase gasoline range olefins and the chemistry of ZSM-5 to crack those olefins. The paper will also describe novel catalytic materials designed to increase propylene. (orig.)

Perovskite ThTaN3: A large-thermopower topological crystalline insulator

Science.gov (United States)

Jung, Myung-Chul; Lee, Kwan-Woo; Pickett, Warren E.

2018-03-01

ThTaN3, a rare cubic perovskite nitride semiconductor, has been studied using ab initio methods. Spin-orbit coupling (SOC) results in band inversion and a band gap of 150 meV at the zone center. Despite trivial Z2 indices, two pairs of spin-polarized surface bands cross the gap near the zone center, indicating that this system is a topological crystalline insulator with the mirror Chern number of | Cm|=2 protected by the mirror and C4 rotational symmetries. Additionally, SOC doubles the Seebeck coefficient, leading to a maximum of ˜400 μ V /K at 150 K for carrier-doping levels of several 1017/cm3.ThTaN3 combines excellent bulk thermopower with parallel conduction through topological surface states that may point toward new possibilities for platforms for engineering devices with larger figures of merit.

Design of an Inductive Adder for the FCC injection kicker pulse generator

Science.gov (United States)

Woog, D.; Barnes, M. J.; Ducimetière, L.; Holma, J.; Kramer, T.

2017-07-01

The injection system for a 100 TeV centre-of-mass collider is an important part of the Future Circular Collider (FCC) study. Due to issues with conventional kicker systems, such as self-triggering and long term availability of thyratrons and limitations of HV-cables, innovative design changes are planned for the FCC injection kicker pulse generator. An inductive adder (IA) based on semiconductor (SC) switches is a promising technology for kicker systems. Its modular design, and the possibility of an active ripple suppression are significant advantages. Since the IA is a complex device, with multiple components whose characteristics are important, a detailed design study and construction of a prototype is necessary. This paper summarizes the system requirements and constraints, and describes the main components and design challenges of the prototype IA. It outlines the results from simulations and measurements on different magnetic core materials as well as on SC switches. The paper concludes on the design choices and progress for the prototype to be built at CERN.

Ab initio random structure search for 13-atom clusters of fcc elements

International Nuclear Information System (INIS)

Chou, J P; Hsing, C R; Wei, C M; Cheng, C; Chang, C M

2013-01-01

The 13-atom metal clusters of fcc elements (Al, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au) were studied by density functional theory calculations. The global minima were searched for by the ab initio random structure searching method. In addition to some new lowest-energy structures for Pd 13 and Au 13 , we found that the effective coordination numbers of the lowest-energy clusters would increase with the ratio of the dimer-to-bulk bond length. This correlation, together with the electronic structures of the lowest-energy clusters, divides the 13-atom clusters of these fcc elements into two groups (except for Au 13 , which prefers a two-dimensional structure due to the relativistic effect). Compact-like clusters that are composed exclusively of triangular motifs are preferred for elements without d-electrons (Al) or with (nearly) filled d-band electrons (Ni, Pd, Cu, Ag). Non-compact clusters composed mainly of square motifs connected by some triangular motifs (Rh, Ir, Pt) are favored for elements with unfilled d-band electrons. (paper)

75 FR 34450 - FCC to Hold Open Commission Meeting Thursday, June 17, 2010

Science.gov (United States)

2010-06-17

..., and bring the benefits of broadband to all Americans. The meeting site is fully accessible to people... www.capitolconnection.gmu.edu http://www.capitolconnection.gmu.edu/ >. Copies of materials adopted at this meeting can be purchased from the FCC's duplicating contractor, Best Copy and Printing, Inc. (202...

Group theoretical treatment of the low-temperature phase transition of the Cd6Ca 1/1-cubic approximant

International Nuclear Information System (INIS)

Tamura, R.; Shibata, K.; Nishimoto, K.; Takeuchi, S.; Edagawa, K.; Saitoh, K.; Isobe, M.; Ueda, Y.

2005-01-01

An antiparallel orientational transition is reported for an intermetallic compound, i.e., Cd 6 Ca crystal, which is a 1/1-1/1-1/1 crystalline approximant to the icosahedral quasicrystal Cd 5.7 Ca. A group theoretical analysis based on the Landau theory predicts that the space group of the low-temperature phase is either C2/c or C2/m, in good agreement with the observations. Accordingly, two types of orientational orderings of Cd 4 tetrahedra, which are located in the center of icosahedral clusters, may occur below 100 K: In both cases, the Cd 4 tetrahedra are orientationally ordered in an antiparallel fashion along the [110] direction of the high temperature body-centered-cubic phase. Such a transition in a metal is reminiscent of orientational transitions in molecular solids

Atomic-scale microstructures, Raman spectra and dielectric properties of cubic pyrochlore-typed Bi1.5MgNb1.5O7 dielectric ceramics

KAUST Repository

Li, Yangyang

2014-07-01

Single-phase cubic pyrochlore-typed Bi1.5MgNb 1.5O7 (BMN) dielectric ceramics were synthesized at temperatures of 1050-1200 °C by solid-state reaction method. Their atomic-scale microstructures and dielectric properties were investigated. X-ray diffraction patterns revealed that the BMN ceramics had an average cubic pyrochlore structure, whereas the Raman spectra indicated that they had an essentially cubic symmetry with small local deviations at the A and O\\' sites of the cubic pyrochlore structure. This was confirmed by selected electron area diffraction (SAED) patterns, where the reflections of {442} (not allowed in the cubic pyrochlore with Fd3̄m symmetry) were clearly observed. SEM and TEM images revealed that the average grain size was increased with the sintering temperature, and an un-homogeneous grain growth was observed at high temperatures. HRTEM images and SAED patterns revealed the single-crystalline nature of the BMN ceramic grains. Energy dispersive spectroscopy (EDS) elemental mapping studies indicated that the compositional distributions of Bi, Mg, Nb and O elements in the ceramic grains were homogenous, and no elemental precipitation was observed at the grain boundary. Quantitative EDS data on ceramic grains revealed the expected cationic stoichiometry based on the initial composition of Bi1.5MgNb1.5O7. Dielectric constants of all the BMN samples exhibited almost frequency independent characteristic in the frequency range of 102-106 Hz, and the highest value was 195 for the BMN ceramics sintered at sintered at 1150 °C with the highest bulk density. The dielectric losses were stable and less than 0.002 in the frequency range of 102-105 Hz. The high dielectric constants of the present BMN samples can be ascribed to the local atomic deviations at the A and O\\' sites from the ideal atomic positions of the pyrochlore structure, which affect the different polarization mechanisms in the BMN ceramics, and which in turn enhance the dielectric

Atomic-scale microstructures, Raman spectra and dielectric properties of cubic pyrochlore-typed Bi1.5MgNb1.5O7 dielectric ceramics

KAUST Repository

Li, Yangyang; Zhu, Xinhua; Al-Kassab, Talaat

2014-01-01

Single-phase cubic pyrochlore-typed Bi1.5MgNb 1.5O7 (BMN) dielectric ceramics were synthesized at temperatures of 1050-1200 °C by solid-state reaction method. Their atomic-scale microstructures and dielectric properties were investigated. X-ray diffraction patterns revealed that the BMN ceramics had an average cubic pyrochlore structure, whereas the Raman spectra indicated that they had an essentially cubic symmetry with small local deviations at the A and O' sites of the cubic pyrochlore structure. This was confirmed by selected electron area diffraction (SAED) patterns, where the reflections of {442} (not allowed in the cubic pyrochlore with Fd3̄m symmetry) were clearly observed. SEM and TEM images revealed that the average grain size was increased with the sintering temperature, and an un-homogeneous grain growth was observed at high temperatures. HRTEM images and SAED patterns revealed the single-crystalline nature of the BMN ceramic grains. Energy dispersive spectroscopy (EDS) elemental mapping studies indicated that the compositional distributions of Bi, Mg, Nb and O elements in the ceramic grains were homogenous, and no elemental precipitation was observed at the grain boundary. Quantitative EDS data on ceramic grains revealed the expected cationic stoichiometry based on the initial composition of Bi1.5MgNb1.5O7. Dielectric constants of all the BMN samples exhibited almost frequency independent characteristic in the frequency range of 102-106 Hz, and the highest value was 195 for the BMN ceramics sintered at sintered at 1150 °C with the highest bulk density. The dielectric losses were stable and less than 0.002 in the frequency range of 102-105 Hz. The high dielectric constants of the present BMN samples can be ascribed to the local atomic deviations at the A and O' sites from the ideal atomic positions of the pyrochlore structure, which affect the different polarization mechanisms in the BMN ceramics, and which in turn enhance the dielectric constants of

Deformation of the cubic open string field theory

Energy Technology Data Exchange (ETDEWEB)

Lee, Taejin, E-mail: taejin@kangwon.ac.kr

2017-05-10

We study a consistent deformation of the cubic open bosonic string theory in such a way that the non-planar world sheet diagrams of the perturbative string theory are mapped onto their equivalent planar diagrams of the light-cone string field theory with some length parameters fixed. An explicit evaluation of the cubic string vertex in the zero-slope limit yields the correct relationship between the string coupling constant and the Yang–Mills coupling constant. The deformed cubic open string field theory is shown to produce the non-Abelian Yang–Mills action in the zero-slope limit if it is defined on multiple D-branes. Applying the consistent deformation systematically to multi-string world sheet diagrams, we may be able to calculate scattering amplitudes with an arbitrary number of external open strings.

Deformation of the cubic open string field theory

International Nuclear Information System (INIS)

Lee, Taejin

2017-01-01

We study a consistent deformation of the cubic open bosonic string theory in such a way that the non-planar world sheet diagrams of the perturbative string theory are mapped onto their equivalent planar diagrams of the light-cone string field theory with some length parameters fixed. An explicit evaluation of the cubic string vertex in the zero-slope limit yields the correct relationship between the string coupling constant and the Yang–Mills coupling constant. The deformed cubic open string field theory is shown to produce the non-Abelian Yang–Mills action in the zero-slope limit if it is defined on multiple D-branes. Applying the consistent deformation systematically to multi-string world sheet diagrams, we may be able to calculate scattering amplitudes with an arbitrary number of external open strings.

Deformation of the cubic open string field theory

Directory of Open Access Journals (Sweden)

Taejin Lee

2017-05-01

Full Text Available We study a consistent deformation of the cubic open bosonic string theory in such a way that the non-planar world sheet diagrams of the perturbative string theory are mapped onto their equivalent planar diagrams of the light-cone string field theory with some length parameters fixed. An explicit evaluation of the cubic string vertex in the zero-slope limit yields the correct relationship between the string coupling constant and the Yang–Mills coupling constant. The deformed cubic open string field theory is shown to produce the non-Abelian Yang–Mills action in the zero-slope limit if it is defined on multiple D-branes. Applying the consistent deformation systematically to multi-string world sheet diagrams, we may be able to calculate scattering amplitudes with an arbitrary number of external open strings.

First-principles calculation of the magnetic properties of paramagnetic fcc iron

International Nuclear Information System (INIS)

Johnson, D.D.; Gyorffy, B.L.; Pinski, F.J.; Staunton, J.; Stocks, G.M.

1985-01-01

Using the disordered local moment picture of itinerant magnetism, we present calculations of the temperature and volume dependence of the magnetic moment and spin-spin correlations for fcc Fe in the paramagnetic state. These calculations are based on the parameter-free, first principles approach of local spin density functional theory and the coherent potential approximation is used to treat the disorder associated with the random orientation of the local moments

Optimising A Read Out for A Possible FCC hh Collision

CERN Document Server

Alagaraisamy, Revathy

2017-01-01

The Future Circular Collider Study (FCC) aims to provide a conceptual design for an accelerator to possibly be constructed in the 2040s-2050s. The most ambitious design proposed is a 100 km-circumference proton-proton collider (FCChh), designed to achieve a centre-of-mass energy of 100 TeV and exceeding . Thus,along with this the precision of the detector is increased via many ways,e.g: calculation and reduction of electronic noise with PCB readout in detector.

Interaction of dispersed cubic phases with blood components

DEFF Research Database (Denmark)

Bode, J C; Kuntsche, Judith; Funari, S S

2013-01-01

The interaction of aqueous nanoparticle dispersions, e.g. based on monoolein/poloxamer 407, with blood components is an important topic concerning especially the parenteral way of administration. Therefore, the influence of human and porcine plasma on dispersed cubic phases was investigated. Part...... activity of cubic phases based on monoolein and poloxamer 188, on soy phosphatidylcholine, glycerol dioleate and polysorbate 80 or the parenteral fat emulsion Lipofundin MCT 20%....

Preparation of spherical and cubic Fe{sub 55}Co{sub 45} microstructures for studying the role of particle morphology in magnetorheological suspensions

Energy Technology Data Exchange (ETDEWEB)

Arief, Injamamul; Mukhopadhyay, P.K., E-mail: pkm@bose.res.in

2014-06-01

Cubic and spherical Fe{sub 55}Co{sub 45} alloyed microstructures were synthesized by borohydride reduction from aqueous solutions of metallic precursors, using stabilizers and polymer. Monosodium citrate, sodium acetate and PEG 6000 were utilized as electrostatic stabilizers and polymeric surface modifier. Suitable reaction conditions were maintained for synthesis of predominantly larger particles (0.7 µm to 1.2 µm), that facilitates use in magnetorheological fluids. Surface morphological studies by scanning electron microscopy revealed well shaped cubic and spherical geometry for the citrate and polymer-stabilized Fe{sub 55}Co{sub 45} alloys, while the alloy compositions remained nearly the same for both. X-ray diffractions of the as-prepared and annealed samples under various temperatures showed high degree of crystallinity with increasing temperatures. Studies of D.C. magnetization of the systems reveal that the particles have a core–shell structure, with inner magnetic core having a diameter around 30 nm with a log-normal distribution. Magnetorheological studies were performed with 8 vol% suspensions of as-synthesized particles dispersed in silicone oil (viscosity 30 mPa s at 25 °C) under different magnetic fields. Detailed studies of the magnetorheological properties were studied on these systems for practical use.

Recovery of Frenkel defects in fcc metals

International Nuclear Information System (INIS)

Chaplin, R.L.; Miller, M.G.

1976-01-01

Because of the production of Frenkel defects occurs most readily along specific crystallographic directions in fcc structures, the recovery mechanism by which annihilation occurs should also be related to the same crystallographic orientations. The recovery path of a diffusing interstitial requires the formation of a temporary metastable state as a close-pair Frenkel defect prior to annihilation. A theoretical treatment of this scheme for interstitial-vacancy recombination shows that during the Isub(D) diffusion there is an experimentally measurable difference if the recovery forms a Isub(B) or a Isub(C) close-pair configuration in aluminum. Experimental results are given which show a difference from the theoretical predictions, and it is concluded that the assumed analytical function describing the interstitial-vacancy distribution created by a 0.4 MeV electron irradiation should be modified. (author)

Influence of Addition of Fluid Catalytic Cracking Residue (FCC and the SiO2 Concentration in Alkali-Activated Ceramic Sanitary-Ware (CSW Binders

Directory of Open Access Journals (Sweden)

Juan Cosa

2018-03-01

Full Text Available Production of Portland cement requires a large volume of natural raw materials and releases huge amounts of CO2 to the atmosphere. Lower environmental impact alternatives focus on alkali-activated cements. In this paper, fluid catalytic cracking residue (FCC was used to partially replace (0 wt %–50 wt % ceramic sanitaryware (CSW in alkali-activated systems. Samples were activated with NaOH and sodium silicate solutions and were cured at 65 °C for 7 days and at 20 °C for 28 and 90 days. In order to increase CSW/FCC binders’ sustainability, the influence of reducing the silica concentration (from 7.28 mol·kg−1 up to 2.91 mol·kg−1 was analyzed. The microstructure of the developed binders was investigated in pastes by X-ray diffraction, thermo tests and field emission scanning electron microscopy analyses. Compressive strength evolution was assessed in mortars. The results showed a synergetic effect of the CSW/FCC combinations so that, under the studied conditions, mechanical properties significantly improved when combining both waste materials (up to 70 MPa were achieved in the mortars containing 50 wt % FCC cured at room temperature for 90 days. Addition of FCC allowed CSW to be activated at room temperature, which significantly broadens the field of applications of alkali-activated CSW binders.

New pathway for the formation of metallic cubic phase Ge-Sb-Te compounds induced by an electric current.

Science.gov (United States)

Park, Yong-Jin; Cho, Ju-Young; Jeong, Min-Woo; Na, Sekwon; Joo, Young-Chang

2016-02-23

The novel discovery of a current-induced transition from insulator to metal in the crystalline phase of Ge2Sb2Te5 and GeSb4Te7 have been studied by means of a model using line-patterned samples. The resistivity of cubic phase Ge-Sb-Te compound was reduced by an electrical current (~1 MA/cm(2)), and the final resistivity was determined based on the stress current density, regardless of the initial resistivity and temperature, which indicates that the conductivity of Ge-Sb-Te compound can be modulated by an electrical current. The minimum resistivity of Ge-Sb-Te materials can be achieved at high kinetic rates by applying an electrical current, and the material properties change from insulating to metallic behavior without a phase transition. The current-induced metal transition is more effective in GeSb4Te7 than Ge2Sb2Te5, which depends on the intrinsic vacancy of materials. Electromigration, which is the migration of atoms induced by a momentum transfer from charge carriers, can easily promote the rearrangement of vacancies in the cubic phase of Ge-Sb-Te compound. This behavior differs significantly from thermal annealing, which accompanies a phase transition to the hexagonal phase. This result suggests a new pathway for modulating the electrical conductivity and material properties of chalcogenide materials by applying an electrical current.

Enhanced bioavailability of nerve growth factor with phytantriol lipid-based crystalline nanoparticles in cochlea

Directory of Open Access Journals (Sweden)

Bu M

2015-11-01

Full Text Available Meng Bu,1,2 Jingling Tang,3 Yinghui Wei,4 Yanhui Sun,1 Xinyu Wang,1 Linhua Wu,2 Hongzhuo Liu1 1School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, People’s Republic of China; 2Department of Pharmacy, the Second Affiliated Hospital, 3School of Pharmacy, Harbin Medical University, Harbin, People’s Republic of China; 4College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, People’s Republic of China Purpose: Supplementation of exogenous nerve growth factor (NGF into the cochlea of deafened animals rescues spiral ganglion cells from degeneration. However, a safe and potent delivery of therapeutic proteins, such as NGF, to spiral ganglion cells remains one of the greatest challenges. This study presents the development of self-assembled cubic lipid-based crystalline nanoparticles to enhance inner ear bioavailability of bioactive NGF via a round window membrane route.Methods: A novel nanocarrier-entrapped NGF was developed based on phytantriol by a liquid precursor dilution, with Pluronic® F127 and propylene glycol as the surfactant and solubilizer, respectively. Upon dilution of the liquid lipid precursors, monodispersed submicron-sized particles with a slight negative charge formed spontaneously.Results: Biological activity of entrapped NGF was assessed using pheochromocytoma cells with NGF-loaded reservoirs to induce significant neuronal outgrowth, similar to that seen in free NGF-treated controls. Finally, a 3.28-fold increase in inner ear bioavailability was observed after administration of phytantriol lipid-based crystalline nanoparticles as compared to free drug, contributing to an enhanced drug permeability of the round window membrane. Conclusion: Data presented here demonstrate the potential of lipid-based crystalline nanoparticles to improve the outcomes of patients bearing cochlear implants. Keywords: nerve growth factor, lipid-based crystalline nanoparticles, PC12 cells, inner ear drug

ESTUDIO COMPARATIVO DE PASTAS DE CEMENTO ADICIONADAS CON CATALIZADOR DE CRAQUEO CATALÍTICO USADO (FCC, Y METACAOLIN (MK

Directory of Open Access Journals (Sweden)

Janneth Torres Agredo

2012-01-01

Full Text Available Este artículo es parte de un proyecto de investigación cuyo objetivo principal es evaluar el desempeño de un residuo de una refinería de petróleo, como adición al cemento Portland con el fin de establecer la viabilidad de su aplicación en materiales de construcción. Este residuo denominado catalizador usado a partir del proceso de craqueo catalítico (fcc procede de las unidades de ruptura catalítica en lecho fluido y está compuesto principalmente por sílice y alúmina. Se analizó la hidratación en pastas de cemento adicionadas con el fcc, y se hizo una comparación con la adición de metacaolín (mk. Para realizar el estudio, se prepararon pastas de cemento Portland Ordinario (opc, adicionadas en porcentajes del 10 y 20% de fcc y mk como reemplazo de cemento. La actividad puzolánica de las adiciones y el tipo de productos de hidratación se determinaron mediante las técnicas de difracción de rayos X (drx y del análisis termogravimétrico (tg/dtg. Como fases principales del proceso de hidratación en las pastas adicionadas con fcc se encontraron silicatos cálcicos hidratados (csh, aluminatos cálcicos hidratados (cah, y silico aluminatos cálcicos (cash, productos similares a los obtenidos en pastas adicionadas con metacaolín.

Numerical modelling of micro-machining of f.c.c. single crystal: Influence of strain gradients

KAUST Repository

Demiral, Murat; Roy, Anish; El Sayed, Tamer S.; Silberschmidt, Vadim V.

2014-01-01

of orthogonal micro-machining of f.c.c. single crystal copper was developed. The model was implemented in a commercial software ABAQUS/Explicit employing a user-defined subroutine VUMAT. Strain-gradient crystal-plasticity and conventional crystal

Physical vapor deposition of cubic boron nitride thin films

International Nuclear Information System (INIS)

Kester, D.J.

1991-01-01

Cubic boron nitride was successfully deposited using physical vapor-deposition methods. RF-sputtering, magnetron sputtering, dual-ion-beam deposition, and ion-beam-assisted evaporation were all used. The ion-assisted evaporation, using boron evaporation and bombardment by nitrogen and argon ions, led to successful cubic boron nitride growth over the widest and most controllable range of conditions. It was found that two factors were important for c-BN growth: bombardment of the growing film and the presence of argon. A systematic study of the deposition conditions was carried out. It was found that the value of momentum transferred into the growing from by the bombarding ions was critical. There was a very narrow transition range in which mixed cubic and hexagonal phase films were prepared. Momentum-per-atom value took into account all the variables involved in ion-assisted deposition: deposition rate, ion energy, ion flux, and ion species. No other factor led to the same control of the process. The role of temperature was also studied; it was found that at low temperatures only mixed cubic and hexagonal material are deposited

d and f electrons in a qp-quantized cubical field

International Nuclear Information System (INIS)

Kibler, M.; Sztucki, J.

1993-03-01

A procedure for qp-quantizing a crystal-field potential V with an arbitrary symmetry G is developed. Such a procedure is applied to the case where V involves cubic components (G=0) of the degrees 4 and 6. This case corresponds to d and f electrons in a qp-quantized cubical potential. It is shown that the qp-quantization of the considered cubical potential is equivalent to a symmetry breaking of type O→D 4 . A general conjecture about this symmetry breaking phenomenon is given. (author) 21 refs

Single crystalline Co3O4 nanocrystals exposed with different crystal planes for Li-O2 batteries.

Science.gov (United States)

Su, Dawei; Dou, Shixue; Wang, Guoxiu

2014-08-29

Single crystalline Co3O4 nanocrystals exposed with different crystal planes were synthesised, including cubic Co3O4 nanocrystals enclosed by {100} crystal planes, pseudo octahedral Co3O4 enclosed by {100} and {110} crystal planes, Co3O4 nanosheets exposed by {110} crystal planes, hexagonal Co3O4 nanoplatelets exposed with {111} crystal planes, and Co3O4 nanolaminar exposed with {112} crystal planes. Well single crystalline features of these Co3O4 nanocrystals were confirmed by FESEM and HRTEM analyses. The electrochemical performance for Li-O2 batteries shows that Co3O4 nanocrystals can significantly reduce the discharge-charge over-potential via the effect on the oxygen evolution reaction (OER). From the comparison on their catalytic performances, we found that the essential factor to promote the oxygen evolution reactions is the surface crystal planes of Co3O4 nanocrystals, namely, crystal planes-dependent process. The correlation between different Co3O4 crystal planes and their effect on reducing charge-discharge over-potential was established: {100} < {110} < {112} < {111}.

Growth of cubic InN on r-plane sapphire

International Nuclear Information System (INIS)

Cimalla, V.; Pezoldt, J.; Ecke, G.; Kosiba, R.; Ambacher, O.; Spiess, L.; Teichert, G.; Lu, H.; Schaff, W.J.

2003-01-01

InN has been grown directly on r-plane sapphire substrates by plasma-enhanced molecular-beam epitaxy. X-ray diffraction investigations have shown that the InN layers consist of a predominant zinc blende (cubic) structure along with a fraction of the wurtzite (hexagonal) phase which content increases with proceeding growth. The lattice constant for zinc blende InN was found to be a=4.986 A. For this unusual growth of a metastable cubic phase on a noncubic substrate an epitaxial relationship was proposed where the metastable zinc blende phase grows directly on the r-plane sapphire while the wurtzite phase arises as the special case of twinning in the cubic structure

Formation of highly structured cubic micellar lipid nanoparticles of soy phosphatidylcholine and glycerol dioleate and their degradation by triacylglycerol lipase.

Science.gov (United States)

Wadsäter, Maria; Barauskas, Justas; Nylander, Tommy; Tiberg, Fredrik

2014-05-28

Lipid nanoparticles of reversed internal phase structures, such as cubic micellar (I2) structure show good drug loading ability of peptides and proteins as well as some small molecules. Due to their controllable small size and inner morphology, such nanoparticles are suitable for drug delivery using several different administration routes, including intravenous, intramuscular, and subcutaneous injection. A very interesting system in this regard, is the two component soy phosphatidylcholine (SPC)/glycerol dioleate (GDO) system, which depending on the ratio of the lipid components form a range of reversed liquid crystalline phases. For a 50/50 (w/w) ratio in excess water, these lipids have been shown to form a reversed cubic micellar (I2) phase of the Fd3m structure. Here, we demonstrate that this SPC/GDO phase, in the presence of small quantities (5-10 wt %) of Polysorbate 80 (P80), can be dispersed into nanoparticles, still with well-defined Fd3m structure. The resulting nanoparticle dispersion has a narrow size distribution and exhibit good long-term stability. In pharmaceutical applications, biodegradation pathways of the drug delivery vehicles and their components are important considerations. In the second part of the study we show how the structure of the particles evolves during exposure to a triacylglycerol lipase (TGL) under physiological-like temperature and pH. TGL catalyzes the lipolytic degradation of acylglycerides, such as GDO, to monoglycerides, glycerol, and free fatty acids. During the degradation, the interior phase of the particles is shown to undergo continuous phase transitions from the reversed I2 structure to structures of less negative curvature (2D hexagonal, bicontinuous cubic, and sponge), ultimately resulting in the formation of multilamellar vesicles.

Effects of Dynamic Impact Loading on Microstructure of FCC (TWIP) Steel

Science.gov (United States)

2014-08-01

the plate to the maximum bulge at the centre of the plate after a blast. Figure 2 shows the aluminium bulge depth measuring device in which the...is shown in Table 1. The most notable feature of the steel is the high level of manganese (18%) combined with significant levels of aluminium ...representatively in the current investigation. Figure 9(a) shows the typical rolling texture components in FCC alloys [12] as reference, consisting of ideal

A Novel FCC Catalyst Based on a Porous Composite Material Synthesized via an In Situ Technique

Directory of Open Access Journals (Sweden)

Shu-Qin Zheng

2015-11-01

Full Text Available To overcome diffusion limitations and improve transport in microporous zeolite, the materials with a wide-pore structure have been developed. In this paper, composite microspheres with hierarchical porous structure were synthesized by an in situ technique using sepiolite, kaolin and pseudoboehmite as raw material. A novel fluid catalytic cracking (FCC catalyst for maximizing light oil yield was prepared based on the composite materials. The catalyst was characterized by XRD, FT-IR, SEM, nitrogen adsorption-desorption techniques and tested in a bench FCC unit. The results indicated that the catalyst had more meso- and macropores and more acid sites than the reference catalyst, and thus can increase light oil yield by 1.31 %, while exhibiting better gasoline and coke selectivity.

The annealing temperature dependences of microstructures and magnetic properties in electro-chemical deposited CoNiFe thin films

International Nuclear Information System (INIS)

Suharyadi, Edi; Riyanto, Agus; Abraha, Kamsul

2016-01-01

CoNiFe thin films with various compositions had been successfully fabricated using electro-chemical deposition method. The crystal structure of Co_6_5Ni_1_5Fe_2_0, Co_6_2Ni_1_5Fe_2_3, and Co_5_5Ni_1_5Fe_3_0 thin films was fcc, bcc-fcc mix, and bcc, respectively. The difference crystal structure results the difference in magnetic properties. The saturation magnetic flux density (Bs) of Co_6_5Ni_1_5Fe_2_0, Co_6_2Ni_1_5Fe_2_3, and Co_5_5Ni_1_5Fe_3_0 thin films was 1.89 T, 1.93 T, and 2.05 T, respectively. An optimal annealing temperature was determined for controlling the microstructure and magnetic properties of CoNiFe thin films. Depending on annealing temperature, the ratio of bcc and fcc structure varied without changing the film composition. By annealing at temperature of T ≥ 350°C, the intensity ratio of X-ray diffraction peaks for bcc(110) to fcc(111) increased. The increase of phase ratio of bcc(110) to fcc(111) caused the increase of Bs, from 1.89 T to 1.95 T. Coercivity (Hc) also increased after annealing, from 2.6 Oe to 18.6 Oe for fcc phase thin films, from 2.0 Oe to 12.0 Oe for fcc-bcc mix phase thin films, and 7.8 Oe to 8 Oe for bcc phase thin films. The changing crystal structures during annealing process indicated that the thermal treatment at high temperature cause the changing crystallinity and atomic displacement. The TEM bright-field images with corresponding selected-area electron diffraction (SAED) patterns showed that there are strongly effects of thermal annealing on the size of fcc and bcc phase crystalline grain as described by size of individual spot and discontinuous rings. The size of crystalline grains increased by thermal annealing. The evolution of bcc and fcc structures of CoNiFe during annealing is though to be responsible for the change of magnetic properties.

Design and performance of an electromagnetic calorimeter for a FCC-hh experiment

Science.gov (United States)

Zaborowska, A.

2018-03-01

The physics reach and feasibility of the Future Circular Collider are currently under investigation. The goal is to collide protons with centre-of-mass energies up to 100 TeV, extending the research carried out at the current HEP facilities. The detectors designed for the FCC experiments need to tackle harsh conditions of the unprecedented collision energy and luminosity. The baseline technology for the calorimeter system of the FCC-hh detector is described. The electromagnetic calorimeter in the barrel, as well as the electromagnetic and hadronic calorimeters in the endcaps and the forward regions, are based on the liquid argon as active material. The detector layout in the barrel region combines the concept of a high granularity calorimeter with precise energy measurements. The calorimeters have to meet the requirements of high radiation hardness and must be able to deal with a very high number of collisions per bunch crossings (pile-up). A very good energy and angular resolution for a wide range of electrons' and photons' momentum is needed in order to meet the demands based on the physics benchmarks. First results of the performance studies with the new liquid argon calorimeter are presented, meeting the energy resolution goal.

Monitoring catalyst flow rate in a FCC cold pilot unity by gamma ray transmission measurements

International Nuclear Information System (INIS)

Brito, Marcio F.P.; Netto, Wilson F.S.; Miranda, Marcia V.F.E.S.; Junior, Isacc A.S.; Dantas, Carlos C.; Melo, Silvio B.; Lima, Emerson A.O.

2013-01-01

A model for monitoring catalyst mass flow in riser of Fluid Catalytic Cracking - FCC, pilot unity as a function of air flow and solid injection is proposed. The fluidized FCC- catalyst bed system is investigated in an experimental setup the Cold Pilot Unity - CPU by means of gamma ray transmission measurements. Riser in CPU simulates the reactor in FCC process. By automation control air flow is instrumentally measured in riser and the solid injection is manually controlled by valve adjusting. Keeping a constant solid injection, catalyst level at the return column was measured by gamma transmission for several air flow values in riser. The operational condition reached a steady state regime before given to setup a new air flow value. A calibration of catalyst level as a function of air flow in riser is calculated, therefore, a model for solid feed rate is derived. Recent published work evaluates solid concentration in riser of the CPU by means of gamma ray transmission, and a correlation with air velocity is obtained. In this work, the model for solid feed rate was further investigated by carrying out experiments to measure catalyst concentration at the same air flow values. These experiments lead to a model for monitoring catalyst flow in riser as function of solid feed rate and air flow. Simulation with random numbers produced with Matlab software allows to define validation criteria for the model parameters. (author)

Diffusion coefficients of rare earth elements in fcc Fe: A first-principles study

Science.gov (United States)

Wang, Haiyan; Gao, Xueyun; Ren, Huiping; Chen, Shuming; Yao, Zhaofeng

2018-01-01

The diffusion data and corresponding detailed insights are particularly important for the understanding of the related kinetic processes in Fe based alloys, e.g. solute strengthening, phase transition, solution treatment etc. We present a density function theory study of the diffusivity of self and solutes (La, Ce, Y and Nb) in fcc Fe. The five-frequency model was employed to calculate the microscopic parameters in the correlation factors of the solute diffusion. The interactions of the solutes with the first nearest-neighbor vacancy (1nn) are all attractive, and can be well understood on the basis of the combination of the strain-relief effects and the electronic effects. It is found that among the investigated species, Ce is the fastest diffusing solute in fcc Fe matrix followed by Nb, and the diffusion coefficients of these two solutes are about an order of magnitude higher than that of Fe self-diffusion. And the results show that the diffusion coefficient of La is slightly higher than that of Y, and both species are comparable to that of Fe self-diffusion.

The attenuation of the periodic table

International Nuclear Information System (INIS)

Cook, N.D.

1990-01-01

Unique among models of nuclear structure, the face-centered-cubic (FCC) lattice model predicts the attenuation of the periodic table at Z < 110 and the impossibility of superheavy nuclei. The total binding energies of superheavy nuclei in the FCC model (109 < Z < 127) were calculated on the basis of parameters obtained from a least-squares best-fit for 914 nuclei (Z < 99). No indication of increased stability is found for any of the transuranic elements

Nature of nitrogen specie in coke and their role in NOx formation during FCC catalyst regeneration

International Nuclear Information System (INIS)

Babich, I.V.; Seshan, K.; Lefferts, L.

2005-01-01

NO x emission during the regeneration of coked fluid catalytic cracking (FCC) catalysts is an environmental problem. In order to follow the route to NO x formation and try to find ways to suppress it, a coked industrial FCC catalyst has been prepared using model N-containing compounds, e.g., pyridine, pyrrole, aniline and hexadecane-pyridine mixture. Nitrogen present in the FCC feed is incorporated as polyaromatic compounds in the coke deposited on the catalyst during cracking. Its functionality has been characterized using XPS. Nitrogen specie of different types, namely, pyridine, pyrrolic or quaternary-nitrogen (Q-N) have been discriminated. Decomposition of the coke during the catalyst regeneration (temperature programmed oxidation (TPO) and isothermal oxidation) has been monitored by GC and MS measurements of the gaseous products formed. The pyrrolic- and pyridinic-type N specie, present more in the outer coke layers, are oxidized under conditions when still large amount of C or CO is available from coke to reduced NO x formed to N 2 . ''Q-N'' type species are present in the inner layer, strongly adsorbed on the acid sites on the catalyst. They are combusted last during regeneration. As most of the coke is already combusted at this point, lack of reductants (C, CO, etc.) results in the presence of NO x in the tail gas

Minimal knotted polygons in cubic lattices

International Nuclear Information System (INIS)

Van Rensburg, E J Janse; Rechnitzer, A

2011-01-01

In this paper we examine numerically the properties of minimal length knotted lattice polygons in the simple cubic, face-centered cubic, and body-centered cubic lattices by sieving minimal length polygons from a data stream of a Monte Carlo algorithm, implemented as described in Aragão de Carvalho and Caracciolo (1983 Phys. Rev. B 27 1635), Aragão de Carvalho et al (1983 Nucl. Phys. B 215 209) and Berg and Foester (1981 Phys. Lett. B 106 323). The entropy, mean writhe, and mean curvature of minimal length polygons are computed (in some cases exactly). While the minimal length and mean curvature are found to be lattice dependent, the mean writhe is found to be only weakly dependent on the lattice type. Comparison of our results to numerical results for the writhe obtained elsewhere (see Janse van Rensburg et al 1999 Contributed to Ideal Knots (Series on Knots and Everything vol 19) ed Stasiak, Katritch and Kauffman (Singapore: World Scientific), Portillo et al 2011 J. Phys. A: Math. Theor. 44 275004) shows that the mean writhe is also insensitive to the length of a knotted polygon. Thus, while these results for the mean writhe and mean absolute writhe at minimal length are not universal, our results demonstrate that these values are quite close the those of long polygons regardless of the underlying lattice and length

A comparative study of the effect of α-, β-, and γ-cyclodextrins as stabilizing agents in the synthesis of silver nanoparticles using a green chemistry method

Energy Technology Data Exchange (ETDEWEB)

Suárez-Cerda, Javier [Centro de Graduados e Investigación, Instituto Tecnológico de Tijuana, Apartado Postal 1166, Tijuana, B. C. (Mexico); Nuñez, Gabriel Alonso [Centro de Nanociencia y Nanotecnología de la UNAM, CNyN, Km. 107 Carretera Tijuana-Ensenada, C.P. 22860 Ensenada, B. C. (Mexico); Espinoza-Gómez, Heriberto [Facultad de Ciencias Químicas e Ingeniería, UABC, Calzada Universidad 14418 Parque Industrial Internacional, C.P. 22390 Tijuana, B.C. (Mexico); Flores-López, Lucía Z., E-mail: lzflores@hotmail.com [Centro de Graduados e Investigación, Instituto Tecnológico de Tijuana, Apartado Postal 1166, Tijuana, B. C. (Mexico)

2014-10-01

This paper describes the effect of different types of cyclodextrins (CDs) in the synthesis of silver nanoparticles (Ag-NPs), using an easy green chemistry method. The Ag-NPs were obtained using an aqueous silver nitrate solution (AgNO{sub 3}) with α-, β-, or γ-CDs (aqueous solutions) as stabilizing agents, employing the chemical reduction method with citric acid as a reducing agent. A comparative study was done to determine which cyclodextrin (CD) was the best stabilizing agent, and we found out that β-CD was the best due to the number of glucopyranose units in its structure. The formation of the Ag-NPs was demonstrated by analysis of UV–vis spectroscopy, atomic force microscopy (AFM), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) and transmission electron microscopy (TEM). SEM–EDS showed the formation of a cluster with a significant amount of silver, for β-CD-Ag-NPs, spherical agglomerates can be observed. However, for α-, γ-CD, the agglomerates do not have a specific form, but their appearance is porous. TEM analysis shows spherical nanoparticles in shape and size between ∼ 0.5 to 7 nm. The clear lattice fringes in TEM images and the typical selected area electron diffraction (SAED) pattern, showed that the Ag-NPs obtained were highly crystalline with a face cubic center structure (FCC). - Highlights: • We report a green chemistry method for silver nanoparticles (Ag-NPs) synthesis. • We study the effect of cyclodextrin type on the silver nanoparticles (Ag-NPs) synthesis. • The silver nanoparticles (Ag-NPs) characterization were done by UV–vis, AFM, SEM–EDS, and TEM. • The Ag-NPs obtained have a face cubic center structure (FCC). • The nanoparticles obtained are spherical in shape and between ∼ 0.5 and 7 nm in size.

A comparative study of the effect of α-, β-, and γ-cyclodextrins as stabilizing agents in the synthesis of silver nanoparticles using a green chemistry method

International Nuclear Information System (INIS)

Suárez-Cerda, Javier; Nuñez, Gabriel Alonso; Espinoza-Gómez, Heriberto; Flores-López, Lucía Z.

2014-01-01

This paper describes the effect of different types of cyclodextrins (CDs) in the synthesis of silver nanoparticles (Ag-NPs), using an easy green chemistry method. The Ag-NPs were obtained using an aqueous silver nitrate solution (AgNO 3 ) with α-, β-, or γ-CDs (aqueous solutions) as stabilizing agents, employing the chemical reduction method with citric acid as a reducing agent. A comparative study was done to determine which cyclodextrin (CD) was the best stabilizing agent, and we found out that β-CD was the best due to the number of glucopyranose units in its structure. The formation of the Ag-NPs was demonstrated by analysis of UV–vis spectroscopy, atomic force microscopy (AFM), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) and transmission electron microscopy (TEM). SEM–EDS showed the formation of a cluster with a significant amount of silver, for β-CD-Ag-NPs, spherical agglomerates can be observed. However, for α-, γ-CD, the agglomerates do not have a specific form, but their appearance is porous. TEM analysis shows spherical nanoparticles in shape and size between ∼ 0.5 to 7 nm. The clear lattice fringes in TEM images and the typical selected area electron diffraction (SAED) pattern, showed that the Ag-NPs obtained were highly crystalline with a face cubic center structure (FCC). - Highlights: • We report a green chemistry method for silver nanoparticles (Ag-NPs) synthesis. • We study the effect of cyclodextrin type on the silver nanoparticles (Ag-NPs) synthesis. • The silver nanoparticles (Ag-NPs) characterization were done by UV–vis, AFM, SEM–EDS, and TEM. • The Ag-NPs obtained have a face cubic center structure (FCC). • The nanoparticles obtained are spherical in shape and between ∼ 0.5 and 7 nm in size

evaluation of commercial FCC catalysts for hydrocarbon conversion. I. Physicochemical characterization and n-hexane conversion.

NARCIS (Netherlands)

Brait, A.; Brait, A.; Seshan, Kulathuiyer; Lercher, J.A.

1998-01-01

The physicochemical properties of six steam-stabilized, commercial FCC catalysts were compared in respect of their catalytic activity for n-hexane conversion. The conversion of n-hexane over these catalysts could be fully explained by three reaction pathways: protolytic cracking, protolytic

Physics Perspectives for a Future Circular Collider: FCC-hh - Accelerator & Detectors

CERN Multimedia

CERN. Geneva

2017-01-01

The lectures will briefly discuss the parameters of a Future Circular Collider, before addressing in detail the physics perspectives and the challenges for the experiments and detector systems. The main focus will be on ee and pp collisions, but opportunities for e—p physics will also be covered. The FCC physics perspectives will be presented with reference to the ongoing LHC programme, including the physics potential from future upgrades to the LHC in luminosity and possibly energy.

Size effect on deformation twinning in face-centred cubic single crystals: Experiments and modelling

International Nuclear Information System (INIS)

Liang, Z.Y.; De Hosson, J.T.M.; Huang, M.X.

2017-01-01

In addition to slip by dislocation glide, deformation twinning in small-sized metallic crystals also exhibits size effect, namely the twinning stress increases with decreasing sample size. In order to understand the underpinning mechanisms responsible for such effect, systematic experiments were carried out on the small-sized single-crystalline pillars of a twinning-induced plasticity steel with a face-centred cubic structure. The flow stress increases considerably with decreasing pillar diameter from 3 to 0.5 μm, demonstrating a substantial size effect with a power exponent of 0.43. Detailed microstructural characterization reveals that the plastic deformation of the present pillars is dominant by twinning, primarily via twin growth, indicating that the size effect should be related to deformation twinning instead of slip by dislocation glide. Subsequent modelling works indicate that twinning can be accomplished by the dissociation of the ion-radiation-induced vacancy Frank loops in the damaged subsurface layer of the pillars, and the size effect is attributed to the ion-radiation-induced compressive stress in the subsurface layer, which decreases with pillar diameter.

On tension-compression asymmetry in ultrafine-grained and nanocrystalline metals

KAUST Repository

Gurses, Ercan; El Sayed, Tamer S.

2010-01-01

We present a physically motivated computational study explaining the tension/compression (T/C) asymmetry phenomenon in nanocrystalline (nc) and ultrafine-grained (ufg) face centered cubic (fcc) metals utilizing a variational constitutive model where

Tuning Eu{sup 3+} emission in europium sesquioxide films by changing the crystalline phase

Energy Technology Data Exchange (ETDEWEB)

Mariscal, A., E-mail: antonio.mariscal@csic.es [Laser Processing Group, Instituto de Óptica, CSIC, C/ Serrano 121, 28006 Madrid (Spain); Quesada, A. [Ceramics for Smart Systems Group, Instituto de Cerámica y Vidrio, C/ Kelsen 5, 28049 Madrid (Spain); Camps, I. [Laser Processing Group, Instituto de Óptica, CSIC, C/ Serrano 121, 28006 Madrid (Spain); Palomares, F.J. [Instituto de Ciencia de Materiales de Madrid, C/ Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain); Fernández, J.F. [Ceramics for Smart Systems Group, Instituto de Cerámica y Vidrio, C/ Kelsen 5, 28049 Madrid (Spain); Serna, R. [Laser Processing Group, Instituto de Óptica, CSIC, C/ Serrano 121, 28006 Madrid (Spain)

2016-06-30

Highlights: • PLD production of high quality europium sesquioxide (Eu{sub 2}O{sub 3}) films. • The deposition of Al{sub 2}O{sub 3} capping and/or buffer layers modifies the crystallization for Eu{sub 2}O{sub 3} films upon annealing. • The formation of cubic or monoclinic phases can be favored. • Eu{sup 3+} emission tuning is achieved as a consequence of crystal field effects. - Abstract: We report the growth of europium sesquioxide (Eu{sub 2}O{sub 3}) thin films by pulsed laser deposition (PLD) in vacuum at room temperature from a pure Eu{sub 2}O{sub 3} ceramic bulk target. The films were deposited in different configurations formed by adding capping and/or buffer layers of amorphous aluminum oxide (a-Al{sub 2}O{sub 3}). The optical properties, refractive index and extinction coefficient of the as deposited Eu{sub 2}O{sub 3} layers were obtained. X-ray photoelectron spectroscopy (XPS) measurements were done to assess its chemical composition. Post-deposition annealing was performed at 500 °C and 850 °C in air in order to achieve the formation of crystalline films and to accomplish photoluminescence emission. According to the analysis of X-ray diffraction (XRD) spectra, cubic and monoclinic phases were formed. It is found that the relative amount of the phases is related to the different film configurations, showing that the control over the crystallization phase can be realized by adequately designing the structures. All the films showed photoluminescence emission peaks (under excitation at 355 nm) that are attributed to the intra 4f-transitions of Eu{sup 3+} ions. The emission spectral shape depends on the crystalline phase of the Eu{sub 2}O{sub 3} layer. Specifically, changes in the hypersensitive {sup 5}D{sub 0} → {sup 7}F{sub 2} emission confirm the strong influence of the crystal field effect on the Eu{sup 3+} energy levels.

Cubic Pencils and Painlev\\'e Hamiltonians

OpenAIRE

Kajiwara, Kenji; Masuda, Tetsu; Noumi, Masatoshi; Ohta, Yasuhiro; Yamada, Yasuhiko

2004-01-01

We present a simple heuristic method to derive the Painlev\\'e differential equations from the corresponding geometry of rational surafces. We also give a direct relationship between the cubic pencils and Seiberg-Witten curves.

Integrable peakon equations with cubic nonlinearity

International Nuclear Information System (INIS)

Hone, Andrew N W; Wang, J P

2008-01-01

We present a new integrable partial differential equation found by Vladimir Novikov. Like the Camassa-Holm and Degasperis-Procesi equations, this new equation admits peaked soliton (peakon) solutions, but it has nonlinear terms that are cubic, rather than quadratic. We give a matrix Lax pair for V Novikov's equation, and show how it is related by a reciprocal transformation to a negative flow in the Sawada-Kotera hierarchy. Infinitely many conserved quantities are found, as well as a bi-Hamiltonian structure. The latter is used to obtain the Hamiltonian form of the finite-dimensional system for the interaction of N peakons, and the two-body dynamics (N = 2) is explicitly integrated. Finally, all of this is compared with some analogous results for another cubic peakon equation derived by Zhijun Qiao. (fast track communication)

Calculations of and evidence for chain packing stress in inverse lyotropic bicontinuous cubic phases.

Science.gov (United States)

Shearman, Gemma C; Khoo, Bee J; Motherwell, Mary-Lynn; Brakke, Kenneth A; Ces, Oscar; Conn, Charlotte E; Seddon, John M; Templer, Richard H

2007-06-19

Inverse bicontinuous cubic lyotropic phases are a complex solution to the dilemma faced by all self-assembled water-amphiphile systems: how to satisfy the incompatible requirements for uniform interfacial curvature and uniform molecular packing. The solution reached in this case is for the water-amphiphile interfaces to deform hyperbolically onto triply periodic minimal surfaces. We have previously suggested that although the molecular packing in these structures is rather uniform the relative phase behavior of the gyroid, double diamond, and primitive inverse bicontinuous cubic phases can be understood in terms of subtle differences in packing frustration. In this work, we have calculated the packing frustration for these cubics under the constraint that their interfaces have constant mean curvature. We find that the relative packing stress does indeed differ between phases. The gyroid cubic has the least packing stress, and at low water volume fraction, the primitive cubic has the greatest packing stress. However, at very high water volume fraction, the double diamond cubic becomes the structure with the greatest packing stress. We have tested the model in two ways. For a system with a double diamond cubic phase in excess water, the addition of a hydrophobe may release packing frustration and preferentially stabilize the primitive cubic, since this has previously been shown to have lower curvature elastic energy. We have confirmed this prediction by adding the long chain alkane tricosane to 1-monoolein in excess water. The model also predicts that if one were able to hydrate the double diamond cubic to high water volume fractions, one should destabilize the phase with respect to the primitive cubic. We have found that such highly swollen metastable bicontinuous cubic phases can be formed within onion vesicles. Data from monoelaidin in excess water display a well-defined transition, with the primitive cubic appearing above a water volume fraction of 0.75. Both of

Comparison of Mechanical Properties of Ni[sub]3Al Thin Films in Disordered FCC and Ordered L1[sub]2 Phases

OpenAIRE

Nix, Wiliam D.; Saha, R.; Aziz, Michael; Hutchinson, John; Evans, Anthony G.; Huang, Yonggang

2001-01-01

We report the results of several experiments isolating the effect of long-range order on mechanical properties of intermetallic compounds. Kinetically disordered FCC Ni3Al (Ni 76%) thin films were produced by rapid solidification following pulsed laser melting. For comparison, compositionally and microstructurally identical films with ordered L12 structure were produced by subsequent annealing at 550 °C for 2 hours. These FCC and L12 Ni3Al thin films were tested by nanoindentation for hardnes...

The Combinatorial Rigidity Conjecture is False for Cubic Polynomials

DEFF Research Database (Denmark)

Henriksen, Christian

2003-01-01

We show that there exist two cubic polynomials with connected Julia sets which are combinatorially equivalent but not topologically conjugate on their Julia sets. This disproves a conjecture by McMullen from 1995.......We show that there exist two cubic polynomials with connected Julia sets which are combinatorially equivalent but not topologically conjugate on their Julia sets. This disproves a conjecture by McMullen from 1995....

Experimental evidence of body centered cubic iron in Earth's core

Science.gov (United States)

Hrubiak, R.; Meng, Y.; Shen, G.

2017-12-01

The Earth's core is mainly composed of iron. While seismic evidence has shown a liquid outer core and a solid inner core, the crystalline nature of the solid iron at the core condition remains debated, largely due to the difficulties in experimental determination of exact polymorphs at corresponding pressure-temperature conditions. We have examined crystal structures of iron up to 220 GPa and 6000 K with x-ray diffraction using a double-sided laser heating system at HPCAT, Advanced Photon Source. The iron sample is confined in a small chamber surrounded by single crystal MgO. The laser power can be modulated together with temperature measurements. The modulated heating of iron in an MgO single crystal matrix allows for microstructure analysis during heating and after the sample is quenched. We present experimental evidence of a body-centered-cubic (BCC) iron from about 100 GPa and 3000 K to at least 220 GPa and 4000 K. The observed BCC phase may be consistent with a theoretically predicted BCC phase that is dynamically stable in similar pressure-temperature conditions [1]. We will discuss the stability region of the BCC phase and the melting curve of iron and their implications in the nature of the Earth's inner core. References: A. B. Belonoshko et al., Nat. Geosci., 1-6 (2017).

Gibbs energy modelling of the driving forces and calculation of the fcc/hcp martensitic transformation temperatures in Fe-Mn and Fe-Mn-Si alloys

International Nuclear Information System (INIS)

Cotes, S.; Fernandez Guillermet, A.; Sade, M.

1999-01-01

Very recent, accurate dilatometric measurements of the fcc hcp martensitic transformation (MT) temperatures are used to develop a new thermodynamic description of the fcc and hcp phases in the Fe-Mn-Si system, based on phenomenological models for the Gibbs energy function. The composition dependence of the driving forces for the fcc→hcp and the hcp→fcc MTs is established. Detailed calculations of the MT temperatures are reported, which are used to investigate the systematic effects of Si additions upon the MT temperatures of Fe-Mn alloys. A critical comparison with one of the most recent thermodynamic analyses of the Fe-Mn-Si system, which is due to Forsberg and Agren, is also presented. (orig.)

Biomimetic Synthesis of Silver Nanoparticles Using Endosymbiotic Bacterium Inhabiting Euphorbia hirta L. and Their Bactericidal Potential

Directory of Open Access Journals (Sweden)

Baker Syed

2016-01-01

Full Text Available The present investigation aims to evaluate biomimetic synthesis of silver nanoparticles using endophytic bacterium EH 419 inhabiting Euphorbia hirta L. The synthesized nanoparticles were initially confirmed with change in color from the reaction mixture to brown indicating the synthesis of nanoparticles. Further confirmation was achieved with the characteristic absorption peak at 440 nm using UV-Visible spectroscopy. The synthesized silver nanoparticles were subjected to biophysical characterization using hyphenated techniques. The possible role of biomolecules in mediating the synthesis was depicted with FTIR analysis. Further crystalline nature of synthesized nanoparticles was confirmed using X-ray diffraction (XRD with prominent diffraction peaks at 2θ which can be indexed to the (111, (200, (220, and (311 reflections of face centered cubic structure (fcc of metallic silver. Transmission electron microscopy (TEM revealed morphological characteristics of synthesized silver nanoparticles to be polydisperse in nature with size ranging from 10 to 60 nm and different morphological characteristics such as spherical, oval, hexagonal, and cubic shapes. Further silver nanoparticles exhibited bactericidal activity against panel of significant pathogenic bacteria among which Pseudomonas aeruginosa was most sensitive compared to other pathogens. To the best of our knowledge, present study forms first report of bacterial endophyte inhabiting Euphorbia hirta L. in mediating synthesizing silver nanoparticles.

Generalized Born-Infeld actions and projective cubic curves

Energy Technology Data Exchange (ETDEWEB)

Ferrara, S. [Department of Physics, CERN Theory Division, CH - 1211 Geneva 23 (Switzerland); INFN - Laboratori Nazionali di Frascati, Via Enrico Fermi 40, I-00044, Frascati (Italy); Porrati, M. [CCPP, Department of Physics, NYU, 4 Washington Pl., New York, NY, 10003 (United States); Sagnotti, A. [Department of Physics, CERN Theory Division, CH - 1211 Geneva 23 (Switzerland); Stora, R. [Department of Physics, CERN Theory Division, CH - 1211 Geneva 23 (Switzerland); Laboratoire d' Annecy-le-Vieux de Physique Theorique (LAPTH), F-74941, Annecy-le-Vieux, Cedex (France); Yeranyan, A. [INFN - Laboratori Nazionali di Frascati, Via Enrico Fermi 40, I-00044, Frascati (Italy); Centro Studi e Ricerche Enrico Fermi, Via Panisperna 89A, 00184, Roma (Italy)

2015-04-01

We investigate U(1){sup n} supersymmetric Born-Infeld Lagrangians with a second non-linearly realized supersymmetry. The resulting non-linear structure is more complex than the square root present in the standard Born-Infeld action, and nonetheless the quadratic constraints determining these models can be solved exactly in all cases containing three vector multiplets. The corresponding models are classified by cubic holomorphic prepotentials. Their symmetry structures are associated to projective cubic varieties. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

FCC Rolling Textures Reviewed in the Light of Quantitative Comparisons between Simulated and Experimental Textures

DEFF Research Database (Denmark)

Wierzbanowski, Krzysztof; Wroński, Marcin; Leffers, Torben

2014-01-01

The crystallographic texture of metallic materials has a very strong effect on the properties of the materials. In the present article, we look at the rolling textures of fcc metals and alloys, where the classical problem is the existence of two different types of texture, the "copper-type texture......" and the "brass-type texture." The type of texture developed is determined by the stacking fault energy of the material, the rolling temperature and the strain rate of the rolling process. Recent texture simulations by the present authors provide the basis for a renewed discussion of the whole field of fcc......} slip without or with deformation twinning, but we also consider slip on other slip planes and slip by partial dislocations. We consistently make quantitative comparison of the simulation results and the experimental textures by means of a scalar correlation factor. We find that the development...

Regulation of Fumonisin B1 Biosynthesis and Conidiation in Fusarium verticillioides by a Cyclin-Like (C-Type) Gene, FCC1†

Science.gov (United States)

Shim, Won-Bo; Woloshuk, Charles P.

2001-01-01

Fumonisins are a group of mycotoxins produced in corn kernels by the plant-pathogenic fungus Fusarium verticillioides. A mutant of the fungus, FT536, carrying a disrupted gene named FCC1 (for Fusarium cyclin C1) resulting in altered fumonisin B1 biosynthesis was generated. FCC1 contains an open reading frame of 1,018 bp, with one intron, and encodes a putative 319-amino-acid polypeptide. This protein is similar to UME3 (also called SRB11 or SSN8), a cyclin C of Saccharomyces cerevisiae, and contains three conserved motifs: a cyclin box, a PEST-rich region, and a destruction box. Also similar to the case for C-type cyclins, FCC1 was constitutively expressed during growth. When strain FT536 was grown on corn kernels or on defined minimal medium at pH 6, conidiation was reduced and FUM5, the polyketide synthase gene involved in fumonisin B1 biosynthesis, was not expressed. However, when the mutant was grown on a defined minimal medium at pH 3, conidiation was restored, and the blocks in expression of FUM5 and fumonisin B1 production were suppressed. Our data suggest that FCC1 plays an important role in signal transduction regulating secondary metabolism (fumonisin biosynthesis) and fungal development (conidiation) in F. verticillioides. PMID:11282612

Stacking fault growth of FCC crystal: The Monte-Carlo simulation approach

International Nuclear Information System (INIS)

Jian Jianmin; Ming Naiben

1988-03-01

The Monte-Carlo method has been used to simulate the growth of the FCC (111) crystal surface, on which is presented the outcrop of a stacking fault. The comparison of the growth rates has been made between the stacking fault containing surface and the perfect surface. The successive growth stages have been simulated. It is concluded that the outcrop of stacking fault on the crystal surface can act as a self-perpetuating step generating source. (author). 7 refs, 3 figs

78 FR 49480 - Proposed Information Collection; Comment Request; NTIA/FCC Web-based Frequency Coordination System

Science.gov (United States)

2013-08-14

... Information Collection; Comment Request; NTIA/FCC Web- based Frequency Coordination System AGENCY: National... the data by means of an internet web-based system. The applications on the Web site provide real-time... INFORMATION: I. Abstract The National Telecommunications and Information Administration (NTIA) hosts a web...

75 FR 42376 - Proposed Information Collection; Comment Request; NTIA/FCC Web-based Frequency Coordination System

Science.gov (United States)

2010-07-21

... Information Collection; Comment Request; NTIA/FCC Web- based Frequency Coordination System AGENCY: National.... Abstract The National Telecommunications and Information Administration (NTIA) hosts a Web-based system...) bands that are shared on a co-primary basis by federal and non-federal users. The Web-based system...

A Bond-Order Potential for Atomistic Simulations in Iron

National Research Council Canada - National Science Library

Rice, Betsy

2000-01-01

.... With a total of 15 fitted parameters, the potential reproduces with only minor deviations to the elastic moduli, the volume-pressure equation of states in the BCC phase, the energies in face-centered cubic (FCC...

Stability and ordering properties of fcc alloys based on Rh, Ir, Pd, and Pt

Czech Academy of Sciences Publication Activity Database

Turchi, P. E. A.; Drchal, Václav; Kudrnovský, Josef

2006-01-01

Roč. 74, č. 6 (2006), 064202/1-064202/12 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z1010914 Keywords : alloy phase stability * ordering in alloys * fcc alloys of Rh, Ir, Pd, Pt Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.107, year: 2006

Growth of cubic GaN on a nitrided AlGaAs (001) substrate by using hydried vapor phase epitaxy

International Nuclear Information System (INIS)

Lee, H. J.; Yang, M.; Ahn, H. S.; Kim, K. H.; Yi, J. Y.; Jang, K. S.; Chang, J. H.; Kim, H. S.; Cho, C. R.; Kim, S. W.

2006-01-01

GaN layers were grown on AlGaAs (001) substrates by using hydride vapor phase epitaxy (HVPE). Growth parameters such as the nitridation temperature of the AlGaAs substrate and the growth rate of the GaN layer were found to be critical determinants for the growth of cubic GaN layer. Nitridation of the AlGaAs surface was performed in a NH 3 atmosphere at a temperature range of 550 - 700 .deg. C. GaN layers were grown at different growth rates on the nitrided AlGaAs substrates. The surface morphologies and the chemical constituents of the nitrided AlGaAs layers were characterized with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). For the optical and the crystalline characterization of the GaN films, cathodoluminescence (CL) and X-ray diffraction (XRD) were carried out.

Three-dimensional periodic dielectric structures having photonic Dirac points

Science.gov (United States)

Bravo-Abad, Jorge; Joannopoulos, John D.; Soljacic, Marin

2015-06-02

The dielectric, three-dimensional photonic materials disclosed herein feature Dirac-like dispersion in quasi-two-dimensional systems. Embodiments include a face-centered cubic (fcc) structure formed by alternating layers of dielectric rods and dielectric slabs patterned with holes on respective triangular lattices. This fcc structure also includes a defect layer, which may comprise either dielectric rods or a dielectric slab with patterned with holes. This defect layer introduces Dirac cone dispersion into the fcc structure's photonic band structure. Examples of these fcc structures enable enhancement of the spontaneous emission coupling efficiency (the .beta.-factor) over large areas, contrary to the conventional wisdom that the .beta.-factor degrades as the system's size increases. These results enable large-area, low-threshold lasers; single-photon sources; quantum information processing devices; and energy harvesting systems.

Three-dimensional periodic dielectric structures having photonic Dirac points

Energy Technology Data Exchange (ETDEWEB)

Bravo-Abad, Jorge; Joannopoulos, John D.; Soljacic, Marin

2015-06-02

The dielectric, three-dimensional photonic materials disclosed herein feature Dirac-like dispersion in quasi-two-dimensional systems. Embodiments include a face-centered cubic (fcc) structure formed by alternating layers of dielectric rods and dielectric slabs patterned with holes on respective triangular lattices. This fcc structure also includes a defect layer, which may comprise either dielectric rods or a dielectric slab with patterned with holes. This defect layer introduces Dirac cone dispersion into the fcc structure's photonic band structure. Examples of these fcc structures enable enhancement of the spontaneous emission coupling efficiency (the .beta.-factor) over large areas, contrary to the conventional wisdom that the .beta.-factor degrades as the system's size increases. These results enable large-area, low-threshold lasers; single-photon sources; quantum information processing devices; and energy harvesting systems.

Some elements go cubic under pressure

Czech Academy of Sciences Publication Activity Database

Legut, Dominik

2007-01-01

Roč. 60, č. 10 (2007), s. 17-17 ISSN 0031-9228 Institutional research plan: CEZ:AV0Z20410507 Keywords : ab initio * polonium * cubic structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.133, year: 2007

Trace spaces in a pre-cubical complex

DEFF Research Database (Denmark)

Raussen, Martin

2009-01-01

In directed algebraic topology, directed irreversible (d)-paths and spaces consisting of d-paths are studied from a topological and from a categorical point of view. Motivated by models for concurrent computation, we study in this paper spaces of d-paths in a pre-cubical complex. Such paths...... are equipped with a natural arc length which moreover is shown to be invariant under directed homotopies. D-paths up to reparametrization (called traces) can thus be represented by arc length parametrized d-paths. Under weak additional conditions, it is shown that trace spaces in a pre-cubical complex...... are separable metric spaces which are locally contractible and locally compact. Moreover, they have the homotopy type of a CW-complex....

The impact of the Family Communication Coordinator (FCC) Protocol on the role stress of hospital chaplains.

Science.gov (United States)

Dodd-McCue, Diane; Tartaglia, Alexander

2005-01-01

The Family Communication Coordinator (FCC) Protocol was implemented to provide early family intervention and to facilitate effective communications during potential organ donation cases. Previous studies found the Protocol associated with improved donor outcome measures and with reduced role stress for ICU nurses caring for potential donors. The present study examines the impact of the Protocol on the perceived role stress of hospital chaplains serving as FCCs. All hospital chaplains serving as FCCs at an academic teaching hospital were surveyed. Their perceptions of job dimensions, role stress, job satisfaction, and commitment were measured; interviews and secondary data supplemented the surveys. The findings demonstrate that the FCC Protocol is associated with improved role stress, specifically role ambiguity and role conflict, among hospital chaplains serving as FCCs. Additionally, the findings suggest that satisfaction with the Protocol may be associated with experience with the Protocol.

Commercial application of titania-supported hydrodesulfurization catalysts in the production of hydrogen using full-range FCC off-gas

Energy Technology Data Exchange (ETDEWEB)

Wang, Shaohu [SINOPEC Wuhan Branch, Qingshan, Wuhan 430082 (China); Shen, Binglong; Qu, Lianglong [Beijing Haishunde Titanium Catalyst Co. Ltd., A-1 North East-Ring Road, Beijing Economic-Technological Development Area, Beijing 100176 (China)

2004-11-24

This paper provides an alternative for low-cost feed used for on-purpose hydrogen production. Full-range FCC off-gas was applied to steam-reforming process as feed after treating with hydrogenation and hydrodesulfurization catalysts. Commercial run results were reported with novel TiO{sub 2}-supported Mo-based catalysts, T205A-1 and T205. The processes of catalysts loading, sulfidation, start-up and long-term run were described in details. Long-term run showed that TiO{sub 2}-supported Mo catalysts have good low-temperature hydrogenation activity, excellent HDS activity, and outstanding stability. Use of FCC off-gas as feed for hydrogen production is quite promising and will increase margins for refiners today.

Ab initio study on the thermal properties of the fcc Al3Mg and Al3Sc alloys

International Nuclear Information System (INIS)

Li Donglin; Chen Ping; Yi Jianxiong; Tang Biyu; Peng Liming; Ding Wenjiang

2009-01-01

Ab initio density functional theory (DFT) and density function perturbation theory (DFPT) have been used to investigate the thermal properties of the fcc Al 3 Mg and Al 3 Sc alloys over a wide range of pressure and temperature, in comparison with fcc Al. Phonon dispersions were obtained at equilibrium and strained configurations by density functional perturbation theory. Using the quasiharmonic approximation for the free energy, several thermal quantities of interest, such as the thermal Grueneisen parameter, heat capacity, thermal expansion coefficient and entropy, were calculated as a function of temperature and pressure, and the variation features of these quantities were discussed in detail. This investigation provides useful information for design and applications of technologically relevant Al-based alloys.

Spontaneous recombination volumes of Frenkel defects in neutron-irradiated non-fcc metals

International Nuclear Information System (INIS)

Nakagawa, M.; Mansel, W.; Boening, K.; Rosner, P.; Vogl, G.

1979-01-01

Production and production-rate curves for the non-fcc metals Fe, Mo, Ta, W, Zr, and Sn are obtained by electrical-resistivity measurements taken at 4.6 K during reactor neutron irradiations. The saturation concentration of Frenkel defects, c/sub s/, and the recombination volume v/sub o/ are evaluated. A parabolic relation between the spontaneous recombination volume v 0 and the compressibility kappa for a series of bcc metals is found

Phase transition of the FCC Ising ferromagnet with competing interactions

International Nuclear Information System (INIS)

Oh, J.H.; Lee, J.Y.; Kim, D.C.

1984-01-01

A molecular field theory with correlation and Monte Carlo simulations are utilized to determine the zero field phase diagram of a fcc Ising model with ferromagnetic nearest neighbor(-J) and antiferromagnetic next neighbor (*aJ) interactions. The correlated molecular field theory predicts a fluctuation induced first order phase transition for 0.87<*a<1.31. Monte Carlo analysis indicates that the first order transition occurs for a somewhat wider range of *a. The transition temperatures obtained by the two methods are in good agreement especially near *a=1 where the fluctuation effect is expected to be large. (Author)

Crystalline color superconductivity

International Nuclear Information System (INIS)

Alford, Mark; Bowers, Jeffrey A.; Rajagopal, Krishna

2001-01-01

In any context in which color superconductivity arises in nature, it is likely to involve pairing between species of quarks with differing chemical potentials. For suitable values of the differences between chemical potentials, Cooper pairs with nonzero total momentum are favored, as was first realized by Larkin, Ovchinnikov, Fulde, and Ferrell (LOFF). Condensates of this sort spontaneously break translational and rotational invariance, leading to gaps which vary periodically in a crystalline pattern. Unlike the original LOFF state, these crystalline quark matter condensates include both spin-zero and spin-one Cooper pairs. We explore the range of parameters for which crystalline color superconductivity arises in the QCD phase diagram. If in some shell within the quark matter core of a neutron star (or within a strange quark star) the quark number densities are such that crystalline color superconductivity arises, rotational vortices may be pinned in this shell, making it a locus for glitch phenomena

The planar cubic Cayley graphs

CERN Document Server

Georgakopoulos, Agelos

2018-01-01

The author obtains a complete description of the planar cubic Cayley graphs, providing an explicit presentation and embedding for each of them. This turns out to be a rich class, comprising several infinite families. He obtains counterexamples to conjectures of Mohar, Bonnington and Watkins. The author's analysis makes the involved graphs accessible to computation, corroborating a conjecture of Droms.

Liquid crystalline phase as a probe for crystal engineering of lactose: carrier for pulmonary drug delivery.

Science.gov (United States)

Patil, Sharvil S; Mahadik, Kakasaheb R; Paradkar, Anant R

2015-02-20

The current work was undertaken to assess suitability of liquid crystalline phase for engineering of lactose crystals and their utility as a carrier in dry powder inhalation formulations. Saturated lactose solution was poured in molten glyceryl monooleate which subsequently transformed into gel. The gel microstructure was analyzed by PPL microscopy and SAXS. Lactose particles recovered from gels after 48 h were analyzed for polymorphism using techniques such as FTIR, XRD, DSC and TGA. Particle size, morphology and aerosolisation properties of prepared lactose were analyzed using Anderson cascade impactor. In situ seeding followed by growth of lactose crystals took place in gels with cubic microstructure as revealed by PPL microscopy and SAXS. Elongated (size ∼ 71 μm) lactose particles with smooth surface containing mixture of α and β-lactose was recovered from gel, however percentage of α-lactose was more as compared to β-lactose. The aerosolisation parameters such as RD, ED, %FPF and % recovery of lactose recovered from gel (LPL) were found to be comparable to Respitose® ML001. Thus LC phase (cubic) can be used for engineering of lactose crystals so as to obtain particles with smooth surface, high elongation ratio and further they can be used as carrier in DPI formulations. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis of PbTe nanocubes, worm-like structures and ...

Indian Academy of Sciences (India)

tions of X-ray diffractograms have shown that the structure of film is found to possess stable face centred cubic (fcc) ... rature), tunable absorption edge, large molar extinction co- .... ative temperature coefficient of resistance which suggested.

Development of local shear bands and orientation gradients in fcc polycrystals

International Nuclear Information System (INIS)

Beaudoin, A.J. Jr.; Mecking, H.; Kocks, U.F.

1995-01-01

A finite element formulation which derives constitutive response from crystal plasticity theory is used to examine localized deformation in fcc polycrystals. The polycrystals are simple, idealized arrangements of grains. Localized deformations within individual grains lead to the development of domains that are separated by boundaries of high misorientation. Shear banding is seen to occur on a microscopic scale of grain dimensions. The important consequences of these simulations are that the predicted local inhomogeneities are meeting various requirements which make them possible nucleation sites for recrystallization

Photonic generation of FCC-compliant UWB pulses based on modified Gaussian quadruplet and incoherent wavelength-to-time conversion

Science.gov (United States)

Mu, Hongqian; Wang, Muguang; Tang, Yu; Zhang, Jing; Jian, Shuisheng

2018-03-01

A novel scheme for the generation of FCC-compliant UWB pulse is proposed based on modified Gaussian quadruplet and incoherent wavelength-to-time conversion. The modified Gaussian quadruplet is synthesized based on linear sum of a broad Gaussian pulse and two narrow Gaussian pulses with the same pulse-width and amplitude peak. Within specific parameter range, FCC-compliant UWB with spectral power efficiency of higher than 39.9% can be achieved. In order to realize the designed waveform, a UWB generator based on spectral shaping and incoherent wavelength-to-time mapping is proposed. The spectral shaper is composed of a Gaussian filter and a programmable filter. Single-mode fiber functions as both dispersion device and transmission medium. Balanced photodetection is employed to combine linearly the broad Gaussian pulse and two narrow Gaussian pulses, and at same time to suppress pulse pedestals that result in low-frequency components. The proposed UWB generator can be reconfigured for UWB doublet by operating the programmable filter as a single-band Gaussian filter. The feasibility of proposed UWB generator is demonstrated experimentally. Measured UWB pulses match well with simulation results. FCC-compliant quadruplet with 10-dB bandwidth of 6.88-GHz, fractional bandwidth of 106.8% and power efficiency of 51% is achieved.

NiFe epitaxial films with hcp and fcc structures prepared on bcc-Cr underlayers

Energy Technology Data Exchange (ETDEWEB)

Higuchi, Jumpei, E-mail: higuchi@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Ohtake, Mitsuru; Sato, Yoichi [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan); Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)

2011-09-30

NiFe epitaxial films are prepared on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers grown hetero-epitaxially on MgO single-crystal substrates by ultra-high vacuum rf magnetron sputtering. The film growth behavior and the crystallographic properties are studied by reflection high energy electron diffraction and pole figure X-ray diffraction. Metastable hcp-NiFe(11-bar 00) and hcp-NiFe(112-bar 0) crystals respectively nucleate on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers, where the hcp-NiFe crystals are stabilized through hetero-epitaxial growth. The hcp-NiFe(11-bar 00) crystal is a single-crystal with the c-axis parallel to the substrate surface, whereas the hcp-NiFe(112-bar 0) crystal is a bi-crystal with the respective c-axes lying in plane and perpendicular each other. With increasing the film thickness, the hcp structure in the NiFe films starts to transform into more stable fcc structure by atomic displacement parallel to the hcp(0001) close packed plane. The resulting films consist of hcp and fcc crystals.

NiFe epitaxial films with hcp and fcc structures prepared on bcc-Cr underlayers

International Nuclear Information System (INIS)

Higuchi, Jumpei; Ohtake, Mitsuru; Sato, Yoichi; Kirino, Fumiyoshi; Futamoto, Masaaki

2011-01-01

NiFe epitaxial films are prepared on Cr(211) bcc and Cr(100) bcc underlayers grown hetero-epitaxially on MgO single-crystal substrates by ultra-high vacuum rf magnetron sputtering. The film growth behavior and the crystallographic properties are studied by reflection high energy electron diffraction and pole figure X-ray diffraction. Metastable hcp-NiFe(11-bar 00) and hcp-NiFe(112-bar 0) crystals respectively nucleate on Cr(211) bcc and Cr(100) bcc underlayers, where the hcp-NiFe crystals are stabilized through hetero-epitaxial growth. The hcp-NiFe(11-bar 00) crystal is a single-crystal with the c-axis parallel to the substrate surface, whereas the hcp-NiFe(112-bar 0) crystal is a bi-crystal with the respective c-axes lying in plane and perpendicular each other. With increasing the film thickness, the hcp structure in the NiFe films starts to transform into more stable fcc structure by atomic displacement parallel to the hcp(0001) close packed plane. The resulting films consist of hcp and fcc crystals.

Atomic vibration amplitudes in fcc and hcp 4He through x-ray diffraction measurements

International Nuclear Information System (INIS)

Venkataraman, C.T.; Simmons, R.O.

2003-01-01

Atomic vibration amplitudes in dense fcc and hcp 4 He crystals have been measured using synchrotron x rays from the dependence of integrated Bragg intensities up to wave vectors of 91 nm -1 . Observed raw Bragg x-ray integrated intensities cover an extraordinary range, greater than 10 5 , due to the combined effect of the Debye-Waller factor and electronic form factor. From analysis of these intensities mean-square atomic vibration amplitudes Q 2 > and Lindemann ratios are determined. Path-integral Monte Carlo (PIMC) computations of Draeger and Ceperley, extrapolated to the thermodynamic limit, provide excellent agreement with these experimental results. For both present measurements and the PIMC results, one finds both a predominantly Gaussian distribution in Q 2 > and an extraordinarily large Lindemann ratio. In contrast, these directly measured x-ray values are significantly larger than published values inferred from Born-von Karman fitting to phonon dispersion measured by neutron scattering. Mildly anharmonic neon, which is fairly well described by self-consistent phonon theories, is contrasted with present results on fcc 4 He at corresponding densities

Lattice mechanical properties of some fcc f-shell metals

International Nuclear Information System (INIS)

Baria, J.K.; Jani, A.R.

2003-01-01

A pseudopotential depending on an effective core radius is proposed to study the binding energy, equation of state, ion-ion interaction, phonon dispersion curves (q-space and r-space analysis), mode Grueneisen parameters and dynamical elastic constants of some fcc f-shell metals La, Yb, Ce and Th. The contribution of the s-like electrons is calculated in the second-order perturbation theory for the potential while d- and f-like electron is taken into account by introducing repulsive short-range Born-Mayer term. The parameter of the potential is evaluated by zero pressure condition. An excellent agreement between theoretical investigations and experimental findings is achieved which confirms the present formalism. (author)

Synthesis of water soluble CdS nanoparticles and study of their DNA damage activity

Directory of Open Access Journals (Sweden)

Kumar Suranjit Prasad

2017-05-01

Full Text Available This study reports a novel method for preparation of water soluble CdS nanoparticles using leaf extract of a plant, Asparagus racemosus. The extract of the leaf tissue which worked as a stabilizing and capping agent, assisted the formation of nanoparticles. Nanoparticles were characterized using a UV–vis spectrophotometer, Photoluminescence, TEM, EDAX, XRD and FT-IR. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, crystalline, CdS of diameter ranging from 2 to 8 nm. X-ray diffraction studies showed the formation of 111, 220 and 311 planes of face-centered cubic (fcc CdS. EDAX analysis confirmed the presence of Cd and S in nanosphere. The cytotoxicity test using MTT assay as well as DNA damage analysis using comet assay revealed that synthesized nano CdS quantum dots (QDs caused less DNA damage and cell death of lymphocytes than pure CdS nanoparticles.

Effect of Steam Deactivation Severity of ZSM-5 Additives on LPG Olefins Production in the FCC Process.

Science.gov (United States)

Gusev, Andrey A; Psarras, Antonios C; Triantafyllidis, Konstantinos S; Lappas, Angelos A; Diddams, Paul A

2017-10-21

ZSM-5-containing catalytic additives are widely used in oil refineries to boost light olefin production and improve gasoline octanes in the Fluid Catalytic Cracking (FCC) process. Under the hydrothermal conditions present in the FCC regenerator (typically >700 °C and >8% steam), FCC catalysts and additives are subject to deactivation. Zeolites (e.g., Rare Earth USY in the base catalyst and ZSM-5 in Olefins boosting additives) are prone to dealumination and partial structural collapse, thereby losing activity, micropore surface area, and undergoing changes in selectivity. Fresh catalyst and additives are added at appropriate respective levels to the FCC unit on a daily basis to maintain overall targeted steady-state (equilibrated) activity and selectivity. To mimic this process under accelerated laboratory conditions, a commercial P/ZSM-5 additive was hydrothermally equilibrated via a steaming process at two temperatures: 788 °C and 815 °C to simulate moderate and more severe equilibration industrial conditions, respectively. n -Dodecane was used as probe molecule and feed for micro-activity cracking testing at 560 °C to determine the activity and product selectivity of fresh and equilibrated P-doped ZSM-5 additives. The fresh/calcined P/ZSM-5 additive was very active in C 12 cracking while steaming limited its activity, i.e., at catalyst-to-feed (C/F) ratio of 1, about 70% and 30% conversion was obtained with the fresh and steamed additives, respectively. A greater activity drop was observed upon increasing the hydrothermal deactivation severity due to gradual decrease of total acidity and microporosity of the additives. However, this change in severity did not result in any selectivity changes for the LPG (liquefied petroleum gas) olefins as the nature (Brønsted-to-Lewis ratio) of the acid/active sites was not significantly altered upon steaming. Steam deactivation of ZSM-5 had also no significant effect on aromatics formation which was enhanced at higher

Effect of Steam Deactivation Severity of ZSM-5 Additives on LPG Olefins Production in the FCC Process

Directory of Open Access Journals (Sweden)

Andrey A. Gusev

2017-10-01

Full Text Available ZSM-5-containing catalytic additives are widely used in oil refineries to boost light olefin production and improve gasoline octanes in the Fluid Catalytic Cracking (FCC process. Under the hydrothermal conditions present in the FCC regenerator (typically >700 °C and >8% steam, FCC catalysts and additives are subject to deactivation. Zeolites (e.g., Rare Earth USY in the base catalyst and ZSM-5 in Olefins boosting additives are prone to dealumination and partial structural collapse, thereby losing activity, micropore surface area, and undergoing changes in selectivity. Fresh catalyst and additives are added at appropriate respective levels to the FCC unit on a daily basis to maintain overall targeted steady-state (equilibrated activity and selectivity. To mimic this process under accelerated laboratory conditions, a commercial P/ZSM-5 additive was hydrothermally equilibrated via a steaming process at two temperatures: 788 °C and 815 °C to simulate moderate and more severe equilibration industrial conditions, respectively. n-Dodecane was used as probe molecule and feed for micro-activity cracking testing at 560 °C to determine the activity and product selectivity of fresh and equilibrated P-doped ZSM-5 additives. The fresh/calcined P/ZSM-5 additive was very active in C12 cracking while steaming limited its activity, i.e., at catalyst-to-feed (C/F ratio of 1, about 70% and 30% conversion was obtained with the fresh and steamed additives, respectively. A greater activity drop was observed upon increasing the hydrothermal deactivation severity due to gradual decrease of total acidity and microporosity of the additives. However, this change in severity did not result in any selectivity changes for the LPG (liquefied petroleum gas olefins as the nature (Brønsted-to-Lewis ratio of the acid/active sites was not significantly altered upon steaming. Steam deactivation of ZSM-5 had also no significant effect on aromatics formation which was enhanced at

RNA aptamers targeted for human αA-crystallin do not bind αB-crystallin, and spare the α-crystallin domain.

Science.gov (United States)

Mallik, Prabhat K; Shi, Hua; Pande, Jayanti

2017-09-16

The molecular chaperones, α-crystallins, belong to the small heat shock protein (sHSP) family and prevent the aggregation and insolubilization of client proteins. Studies in vivo have shown that the chaperone activity of the α-crystallins is raised or lowered in various disease states. Therefore, the development of tools to control chaperone activity may provide avenues for therapeutic intervention, as well as enable a molecular understanding of chaperone function. The major human lens α-crystallins, αA- (HAA) and αB- (HAB), share 57% sequence identity and show similar activity towards some clients, but differing activities towards others. Notably, both crystallins contain the "α-crystallin domain" (ACD, the primary client binding site), like all other members of the sHSP family. Here we show that RNA aptamers selected for HAA, in vitro, exhibit specific affinity to HAA but do not bind HAB. Significantly, these aptamers also exclude the ACD. This study thus demonstrates that RNA aptamers against sHSPs can be designed that show high affinity and specificity - yet exclude the primary client binding region - thereby facilitating the development of RNA aptamer-based therapeutic intervention strategies. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of quadratic and cubic nonlinearities on a perfectly tuned parametric amplifier

DEFF Research Database (Denmark)

Neumeyer, Stefan; Sorokin, Vladislav; Thomsen, Jon Juel

2016-01-01

We consider the performance of a parametric amplifier with perfect tuning (two-to-one ratio between the parametric and direct excitation frequencies) and quadratic and cubic nonlinearities. A forced Duffing–Mathieu equation with appended quadratic nonlinearity is considered as the model system......, and approximate analytical steady-state solutions and corresponding stabilities are obtained by the method of varying amplitudes. Some general effects of pure quadratic, and mixed quadratic and cubic nonlinearities on parametric amplification are shown. In particular, the effects of mixed quadratic and cubic...... nonlinearities may generate additional amplitude–frequency solutions. In this case an increased response and a more phase sensitive amplitude (phase between excitation frequencies) is obtained, as compared to the case with either pure quadratic or cubic nonlinearity. Furthermore, jumps and bi...

Curie temperatures of fcc and bcc Nickel and Permalloy: Supercell and Green's function methods

Czech Academy of Sciences Publication Activity Database

Yu, P.; Jin, X.F.; Kudrnovský, Josef; Wang, D. S.; Bruno, P.

2008-01-01

Roč. 77, č. 5 (2008), 054431/1-054431/8 ISSN 1098-0121 R&D Projects: GA MŠk OC 150; GA AV ČR IAA100100616 Institutional research plan: CEZ:AV0Z10100520 Keywords : fcc - and bcc-Ni * Permalloy * magnetic moments * Curie temperatures Subject RIV: BE - Theoretical Physics Impact factor: 3.322, year: 2008

[Multimodal medical image registration using cubic spline interpolation method].

Science.gov (United States)

He, Yuanlie; Tian, Lianfang; Chen, Ping; Wang, Lifei; Ye, Guangchun; Mao, Zongyuan

2007-12-01

Based on the characteristic of the PET-CT multimodal image series, a novel image registration and fusion method is proposed, in which the cubic spline interpolation method is applied to realize the interpolation of PET-CT image series, then registration is carried out by using mutual information algorithm and finally the improved principal component analysis method is used for the fusion of PET-CT multimodal images to enhance the visual effect of PET image, thus satisfied registration and fusion results are obtained. The cubic spline interpolation method is used for reconstruction to restore the missed information between image slices, which can compensate for the shortage of previous registration methods, improve the accuracy of the registration, and make the fused multimodal images more similar to the real image. Finally, the cubic spline interpolation method has been successfully applied in developing 3D-CRT (3D Conformal Radiation Therapy) system.

Regularizing cubic open Neveu-Schwarz string field theory

International Nuclear Information System (INIS)

Berkovits, Nathan; Siegel, Warren

2009-01-01

After introducing non-minimal variables, the midpoint insertion of Y Y-bar in cubic open Neveu-Schwarz string field theory can be replaced with an operator N ρ depending on a constant parameter ρ. As in cubic open superstring field theory using the pure spinor formalism, the operator N ρ is invertible and is equal to 1 up to a BRST-trivial quantity. So unlike the linearized equation of motion Y Y-bar QV = 0 which requires truncation of the Hilbert space in order to imply QV = 0, the linearized equation N ρ QV = 0 directly implies QV = 0.

Identifying self-interstitials of bcc and fcc crystals in molecular dynamics

Science.gov (United States)

Bukkuru, S.; Bhardwaj, U.; Warrier, M.; Rao, A. D. P.; Valsakumar, M. C.

2017-02-01

Identification of self-interstitials in molecular dynamics (MD) simulations is of critical importance. There exist several criteria for identifying the self-interstitial. Most of the existing methods use an assumed cut-off value for the displacement of an atom from its lattice position to identify the self-interstitial. The results obtained are affected by the chosen cut-off value. Moreover, these chosen cut-off values are independent of temperature. We have developed a novel unsupervised learning algorithm called Max-Space Clustering (MSC) to identify an appropriate cut-off value and its dependence on temperature. This method is compared with some widely used methods such as effective sphere (ES) method and nearest neighbor sphere (NNS) method. The cut-off radius obtained using our method shows a linear variation with temperature. The value of cut-off radius and its temperature dependence is derived for five bcc (Cr, Fe, Mo, Nb, W) and six fcc (Ag, Au, Cu, Ni, Pd, Pt) crystals. It is seen that the ratio of the cut-off values "r" to the lattice constant "a" lies between 0.23 and 0.3 at 300 K and this ratio is on an average smaller for the fcc crystals. Collision cascade simulations are carried out for Primary knock-on Atom (PKA) energies of 5 keV in Fe (at 300 K and 1000 K) and W (at 300 K and 2500 K) and the results are compared using the various methods.

Cubic phase nanoparticles for sustained release of ibuprofen: formulation, characterization, and enhanced bioavailability study

Science.gov (United States)

Dian, Linghui; Yang, Zhiwen; Li, Feng; Wang, Zhouhua; Pan, Xin; Peng, Xinsheng; Huang, Xintian; Guo, Zhefei; Quan, Guilan; Shi, Xuan; Chen, Bao; Li, Ge; Wu, Chuanbin

2013-01-01

In order to improve the oral bioavailability of ibuprofen, ibuprofen-loaded cubic nanoparticles were prepared as a delivery system for aqueous formulations. The cubic inner structure was verified by cryogenic transmission electron microscopy. With an encapsulation efficiency greater than 85%, the ibuprofen-loaded cubic nanoparticles had a narrow size distribution around a mean size of 238 nm. Differential scanning calorimetry and X-ray diffraction determined that ibuprofen was in an amorphous and molecular form within the lipid matrix. The in vitro release of ibuprofen from cubic nanoparticles was greater than 80% at 24 hours, showing sustained characteristics. The pharmacokinetic study in beagle dogs showed improved absorption of ibuprofen from cubic nanoparticles compared to that of pure ibuprofen, with evidence of a longer half-life and a relative oral bioavailability of 222% (P ibuprofen-loaded cubic nanoparticles provide a promising carrier candidate with an efficient drug delivery for therapeutic treatment. PMID:23468008

Nickel and cobalt filled multiwalled carbon nantubes : structural transformation under heavy ion irradiation and high pressure

International Nuclear Information System (INIS)

Misra, D.S.; Misra, A.; Tyagi, Pawan K.; Karamakar, S.; Sharma, Surinder M.

2006-01-01

Full text: The nickel and cobalt nano wires of diameters ranging from 5-15 nm are formed inside the multiwalled carbon nantubes using microwave plasma chemical vapor deposition in our laboratory. The nano wires inside the tubes are found to have a perfect crystalline structure and the crystalline planes of (111) orientations are aligned for FCC nickel and cobalt in a particular fashion. We find that the cobalt can exist either in FCC or HCP phase in confinement depending upon the diameter of the tubes. The irradiation of these nanowires with high energy Au + ions alter the orientation of the crystalline planes and generate various types of domains and defects in the nanowires. The complete amorphization of the walls of the nano tubes is observed at the fluence of 5x10 13 /cm 2 and results in amorphization of nickel nano wires as well. The cobalt nano wires have FCC structure in ambient conditions and transform to HCP cobalt irreversibly when subjected to high pressure of ∼9 GPa. Multi-walled carbon nano tubes that encapsulate the cobalt nano wires do not undergo any other structural transformation with pressure except partial reversible amorphization beyond 9 GPa

Numbers for reducible cubic scrolls

Directory of Open Access Journals (Sweden)

Israel Vainsencher

2004-12-01

Full Text Available We show how to compute the number of reducible cubic scrolls of codimension 2 in (math blackboard symbol Pn incident to the appropriate number of linear spaces.Mostramos como calcular o número de rolos cúbicos redutíveis de codimensão 2 em (math blackboard symbol Pn incidentes a espaços lineares apropriados.

Physics perspectives for a Future Circular Collider: FCC-hh/eh - Physics-Perspectives

CERN Multimedia

CERN. Geneva

2017-01-01

The lectures will briefly discuss the parameters of a Future Circular Collider, before addressing in detail the physics perspectives and the challenges for the experiments and detector systems. The main focus will be on ee and pp collisions, but opportunities for e—p physics will also be covered. The FCC physics perspectives will be presented with reference to the ongoing LHC programme, including the physics potential from future upgrades to the LHC in luminosity and possibly energy.

Periodic order and defects in Ni-based inverse opal-like crystals on the mesoscopic and atomic scale

OpenAIRE

Chumakova, A. V.; Valkovskiy, G. A.; Mistonov, A. A.; Dyadkin, V. A.; Grigoryeva, N. A.; Sapoletova, N. A.; Napolskii, K. S.; Eliseev, A. A.; Petukhov, Andrei V.; Grigoriev, S. V.

2014-01-01

The structure of inverse opal crystals based on nickel was probed on the mesoscopic and atomic levels by a set of complementary techniques such as scanning electron microscopy and synchrotron microradian and wide-angle diffraction. The microradian diffraction revealed the mesoscopic-scale face-centered-cubic (fcc) ordering of spherical voids in the inverse opal-like structure with unit cell dimension of 750±10nm. The diffuse scattering data were used to map defects in the fcc structure as a f...

Cobalt nanorods fully encapsulated in carbon nanotube and magnetization measurements by off-axis electron holography

International Nuclear Information System (INIS)

Fujita, Takeshi; Hayashi, Yasuhiko; Tokunaga, Tomoharu; Yamamoto, Kazuo

2006-01-01

Fully encapsulated face-centered-cubic (fcc) Co nanorods in multiwalled carbon nanotubes were produced by microwave plasma enhanced chemical vapor deposition. Quantitative magnetization measurements of the Co nanorods were carried out by off-axis electron holography using a theoretical cylindrical model. The component of magnetic induction was then measured to be 1.2±0.1 T, which is lower than the expected saturation magnetization of fcc Co of 1.7 T. The reason for the reduced magnetic component was discussed

Crystalline and amorphous phases in carbon nitride films produced by intense high-pressure plasma

International Nuclear Information System (INIS)

Gurarie, V.N.; Orlov, A.V.; Bursill, L.A.; JuLin, P.; Nugent, K.W.; Chon, J.W.; Prawer, S.

1997-01-01

Carbon-nitride films are prepared using a high-intensity pulsed plasma deposition technique. A wide range of nitrogen pressure and discharge intensity are used to investigate their effect on the morphology, nitrogen content, structure, bonding, phase composition and mechanical characteristics of the CN films deposited. Increasing the nitrogen pressure from 0.1 atm to 10 atm results in an increase of nitrogen incorporation into CN films to maximum of 45 at %. Under the high-energy density deposition conditions which involve ablation of the quartz substrate the CN films are found to incorporate in excess of 60 at %N. Raman spectra of these films contain sharp peaks characteristic of a distinct crystalline CN phase. TEM diffraction patterns for the films deposited below 1 atm unambiguously show the presence of micron-sized crystals displaying a cubic symmetry. (authors)

Simulation of short-term annealing of displacement cascades in FCC metals

International Nuclear Information System (INIS)

Heinisch, H.L.; Doran, D.G.; Schwartz, D.M.

1980-01-01

Computer models have been developed for the simulation of high energy displacement cascades. The objective is the generation of defect production functions for use in correlation analysis of radiation effects in fusion reactor materials. In particular, the stochastic cascade annealing simulation code SCAS has been developed and used to model the short-term annealing behavior of simulated cascades in FCC metals. The code is fast enough to make annealing of high energy cascades practical. Sets of cascades from 5 keV to 100 keV in copper were generated by the binary collision code MARLOWE

Hierarchically Ordered Supramolecular Protein-Polymer Composites with Thermoresponsive Properties

Directory of Open Access Journals (Sweden)

Salla Välimäki

2015-05-01

Full Text Available Synthetic macromolecules that can bind and co-assemble with proteins are important for the future development of biohybrid materials. Active systems are further required to create materials that can respond and change their behavior in response to external stimuli. Here we report that stimuli-responsive linear-branched diblock copolymers consisting of a cationic multivalent dendron with a linear thermoresponsive polymer tail at the focal point, can bind and complex Pyrococcus furiosus ferritin protein cages into crystalline arrays. The multivalent dendron structure utilizes cationic spermine units to bind electrostatically on the surface of the negatively charged ferritin cage and the in situ polymerized poly(di(ethylene glycol methyl ether methacrylate linear block enables control with temperature. Cloud point of the final product was determined with dynamic light scattering (DLS, and it was shown to be approximately 31 °C at a concentration of 150 mg/L. Complexation of the polymer binder and apoferritin was studied with DLS, small-angle X-ray scattering, and transmission electron microscopy, which showed the presence of crystalline arrays of ferritin cages with a face-centered cubic (fcc, \\( Fm\\overline{3}m \\ Bravais lattice where lattice parameter a = 18.6 nm. The complexation process was not temperature dependent but the final complexes had thermoresponsive characteristics with negative thermal expansion.

High temperature electrical resistivity and Seebeck coefficient of Ge2Sb2Te5 thin films

Science.gov (United States)

Adnane, L.; Dirisaglik, F.; Cywar, A.; Cil, K.; Zhu, Y.; Lam, C.; Anwar, A. F. M.; Gokirmak, A.; Silva, H.

2017-09-01

High-temperature characterization of the thermoelectric properties of chalcogenide Ge2Sb2Te5 (GST) is critical for phase change memory devices, which utilize self-heating to quickly switch between amorphous and crystalline states and experience significant thermoelectric effects. In this work, the electrical resistivity and Seebeck coefficient are measured simultaneously as a function of temperature, from room temperature to 600 °C, on 50 nm and 200 nm GST thin films deposited on silicon dioxide. Multiple heating and cooling cycles with increasingly maximum temperature allow temperature-dependent characterization of the material at each crystalline state; this is in contrast to continuous measurements which return the combined effects of the temperature dependence and changes in the material. The results show p-type conduction (S > 0), linear S(T), and a positive Thomson coefficient (dS/dT) up to melting temperature. The results also reveal an interesting linearity between dS/dT and the conduction activation energy for mixed amorphous-fcc GST, which can be used to estimate one parameter from the other. A percolation model, together with effective medium theory, is adopted to correlate the conductivity of the material with average grain sizes obtained from XRD measurements. XRD diffraction measurements show plane-dependent thermal expansion for the cubic and hexagonal phases.

Modeling the dispersion of atmospheric pollution using cubic splines and chapeau functions

Energy Technology Data Exchange (ETDEWEB)

Pepper, D W; Kern, C D; Long, P E

1979-01-01

Two methods that can be used to solve complex, three-dimensional, advection-diffusion transport equations are investigated. A quasi-Lagrangian cubic spline method and a chapeau function method are compared in advecting a passive scalar. The methods are simple to use, computationally fast, and reasonably accurate. Little numerical dissipation is manifested by the schemes. In simple advection tests with equal mesh spacing, the chapeau function method maintains slightly more accurate peak values than the cubic spline method. In tests with unequal mesh spacing, the cubic spline method has less noise, but slightly more damping than the standard chapeau method has. Both cubic splines and chapeau functions can be used to solve the three-dimensional problem of gaseous emissions dispersion without excessive programing complexity or storage requirements. (10 diagrams, 39 references, 2 tables)

Unified treatment of coupled optical and acoustic phonons in piezoelectric cubic materials

DEFF Research Database (Denmark)

Willatzen, Morten; Wang, Zhong Lin

2015-01-01

A unified treatment of coupled optical and acoustic phonons in piezoelectric cubic materials is presented whereby the lattice displacement vector and the internal ionic displacement vector are found simultaneously. It is shown that phonon couplings exist in pairs only; either between the electric...... piezoelectricity in a cubic structured material slab. First, it is shown that isolated optical phonon modes generally cannot exist in piezoelectric cubic slabs. Second, we prove that confined acousto-optical phonon modes only exist for a discrete set of in-plane wave numbers in piezoelectric cubic slabs. Third...... potential and the lattice displacement coordinate perpendicular to the phonon wave vector or between the two other lattice displacement components. The former leads to coupled acousto-optical phonons by virtue of the piezoelectric effect. We then establish three new conjectures that entirely stem from...

Interfacial morphologies and growth modes of F.C.C. metallic crystals from liquid alloys

International Nuclear Information System (INIS)

Camel, Denis

1980-01-01

Equilibrium and growth morphologies of f.c.c. metallic crystals in contact with liquid alloys have been observed in-situ using transmission electron microscopy. These morphologies have been discussed in terms of atomic interfacial structure and growth mechanisms with the help of a statistical thermodynamic model which takes into account the effects of chemical interactions and interfacial adsorption. (author) [fr

Liquid crystalline order in polymers

CERN Document Server

Blumstein, Alexandre

1978-01-01

Liquid Crystalline Order in Polymers examines the topic of liquid crystalline order in systems containing rigid synthetic macromolecular chains. Each chapter of the book provides a review of one important area of the field. Chapter 1 discusses scattering in polymer systems with liquid crystalline order. It also introduces the field of liquid crystals. Chapter 2 treats the origin of liquid crystalline order in macromolecules by describing the in-depth study of conformation of such macromolecules in their unassociated state. The chapters that follow describe successively the liquid crystalli

Low-pH-Induced Lamellar to Bicontinuous Primitive Cubic Phase Transition in Dioleoylphosphatidylserine/Monoolein Membranes.

Science.gov (United States)

Oka, Toshihiko; Hasan, Moynul; Islam, Md Zahidul; Moniruzzaman, Md; Yamazaki, Masahito

2017-10-31

Electrostatic interactions (EIs) play important roles in the structure and stability of inverse bicontinuous cubic (Q II ) phases of lipid membranes. We examined the effect of pH on the phase of dioleoylphosphatidylserine (DOPS)/monoolein (MO) membranes at low ionic strengths using small-angle X-ray scattering (SAXS). We found that the phase transitions from lamellar liquid-crystalline (L α ) to primitive cubic (Q II P ) phases in DOPS/MO (2/8 molar ratio) membranes occurred in buffers containing 50 mM NaCl at and below the final pH of 2.75 as the pH of the membrane suspension was decreased from a neutral value. The kinetic pathway of this transition was revealed using time-resolved SAXS with a stopped-flow apparatus. The first step is a rapid transition from the L α phase to the hexagonal II (H II ) phase, and the second step is a slow transition from the H II phase to the Q II P phase. We determined the rate constants of the first step, k 1 , and of the second step, k 2 , by analyzing the time course of SAXS intensities quantitatively. The k 1 value increased with temperature. The analysis of this result provided the values of its apparent activation energy, which were constant over temperature but increased with pH. This can be explained by an EI effect on the free energy of the transition state. In contrast, the k 2 value decreased with temperature, indicating that the true activation energy increased with temperature. These experimental results were analyzed using the theory of the activation energy of phase transitions of lipid membranes when the free energy of the transition state depends on temperature. On the basis of these results, we discussed the mechanism of this phase transition.

Air annealing induced transformation of cubic CdSe microspheres into hexagonal nanorods and micro-pyramids

Energy Technology Data Exchange (ETDEWEB)

Kale, Rohidas B., E-mail: rb_kale@yahoo.co.in [Department of Physics, Institute of Science, Mumbai 400032, M.S. (India); Lu, Shih-Yuan, E-mail: sylu@mx.nthu.edu.tw [Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu 30013, Taiwan (China)

2015-08-15

Highlights: • Nanocrystalline CdSe thin films were deposited using inexpensive CBD method. • Air annealing induced structural and interesting morphological transformation. • The as-deposited CdSe thin films showed a blue shift in its optical spectra. • The films showed a red shift in their optical spectra after annealing. - Abstract: CdSe thin films have been deposited onto glass substrates using a chemical bath deposition method at relatively low temperatures (40 °C). The precursors used for the deposition of the thin films are cadmium nitrate hexahydrate, freshly prepared sodium selenosulfate solution and aqueous ammonia solution as a complex as well as pH adjusting reagent. In order to study the influence of air annealing on their physicochemical properties, the as-deposited CdSe thin films were further annealed at 200 °C and 400 °C for 3 h in air atmosphere. Significant changes in the morphology and photonic properties were clearly observed after the thermal annealing of the CdSe thin films. The as-deposited CdSe films grow with the cubic phase that transforms into mixed cubic and hexagonal wurtzite phase with improved crystalline quality of the films after the air annealing. Morphological observation reveals that the as-deposited thin films grow with multilayer that consists of network or mesh like structure, uniformly deposited on the glass substrate over which microspheres are uniformly distributed. After air annealing, CdSe nanorods emerged from the microspheres along with conversion of few microspheres into micro-pyramids. The UV–visible study illustrates that the as-deposited thin film shows blue shifts in its optical spectrum and the spectrum was red-shifted after annealing the CdSe thin films. The band gap of the CdSe thin films were found to be decreased after the thermal treatment.

The FCC process as a producer of light olefins

International Nuclear Information System (INIS)

Yung, K.Y.; Yanik, S.; O'Connor, P.; Pouwels, C.

1992-01-01

To reduce emissions from the gasoline engine, aromatics content and vapor pressure of the motor gasoline pool will be reduced and a minimum amount of oxygen will be mandated. This reformulation will limit the application of high octane components like benzene, toluene and butanes and will require the use of oxygenates. To compensate for the loss in octane, the use of alkylate and, of course also oxygenates will grow. The Fluid Catalytic Cracking Unit is, as producer of (olefinic) propanes, butanes and pentanes, an important feedstock producer for alkylate and oxygenate producing process. Hence, process adjustments and FCC catalyst formations to increase the yield of above desirable light products are of prime importance and will be dealt with in this paper

Polarization Change in Face-Centered Cubic Opal Films

Science.gov (United States)

Wolff, Christian; Romanov, Sergei; Küchenmeister, Jens; Peschel, Ulf; Busch, Kurt

2011-10-01

Artificial opals are a popular platform for investigating fundamental properties of Photonic Crystals (PhC). In this work, we provide a theoretical analysis of polarization-resolved transmission experiments through thin opal films. Despite the full cubic symmetry of the PhC, this system provides a very efficient mechanism for manipulating the polarization state of light. Based on band structure calculations and Bloch mode analysis, we find that this effect closely resembles classical birefringence. Due to the cubic symmetry, however, a description using tensorial quantities is not possible. This indicates fundamental limitations of effective material models for Photonic Crystals and demonstrates the importance of accurately modelling the microscopic geometry of such systems.

Adaption of the LHC cold mass cooling system to the requirements of the Future Circular Collider (FCC)

Science.gov (United States)

Kotnig, C.; Tavian, L.; Brenn, G.

2017-12-01

The cooling of the superconducting magnet cold masses with superfluid helium (He II) is a well-established concept successfully in operation for years in the LHC. Consequently, its application for the cooling of FCC magnets is an obvious option. The 12-kW heat loads distributed over 10-km long sectors not only require an adaption of the magnet bayonet heat exchangers but also present new challenges to the cryogenic plants, the distribution system and the control strategy. This paper recalls the basic LHC cooling concept with superfluid helium and defines the main parameters for the adaption to the FCC requirements. Pressure drop and hydrostatic head are developed in the distribution and pumping systems; their impact on the magnet temperature profile and the corresponding cooling efficiency is presented and compared for different distribution and pumping schemes.

Prediction of the forming-limit curve in steels using crystalline plasticity

International Nuclear Information System (INIS)

Signorelli, J; Bolmaro, R; Turner, P; Bertinetti, M; Insausti, J; Lucaioli, A; Garc, C; Iurman, L

2006-01-01

Forming-limit curves (FLD) are predicted by using crystalline plasticity together with the Marciniak-Kuczynski (MK) model. The location on the sheet is modeled through the presence of an initial imperfection on a thin band of material. The deformations within and outside the band are supposed to be homogenous. Conditions of compatibility and equilibrium are imposed in the interface. Therefore, the polycrystalline model is applied to both sides of the sheet (inside and outside the band). The constitutive law at simple scale crystal is visco-plastic, while the response of the aggregate is obtained with the visco-plastic self-consistent approach (VPSC) . The experiences will be carried out using two plates of two embedding qualities. The consistency of the model predictions will be verified in both cases with experimental results. Tests with uniaxial traction, plane deformation traction and biaxial traction with hydraulic cupping and SWIFT embedding with a plane punch will be carried out to obtain the embedding limit relationships. This work analyzed the formability of two steel qualities that are fit for embedding. Approximately 1mm thick sheets were examined by simple mechanical testing, their forming-limit curves and crystallographic texture at the start and finish of the test. The results were also analyzed based on numerical simulations using a crystalline plasticity model together with the methodology proposed by Marciniak y Kuczynski. The results show that the simulated FLDs using MK-VPSC agree acceptably with the available experimental evidence. The values of simulated limit deformation for both materials are similar. Such behavior may be explained by the similarity in the values for n, grain shape, CRSS and initial texture of both plates. The proposed calculation model MK-VPSC also substantially improves the MK-Taylor approximation used by Inal et al. This approximation heavily overestimates the limit deformation values for a BCC structure like the steels

Microstructure-sensitive modelling of dislocation creep in polycrystalline FCC alloys: Orowan theory revisited

Energy Technology Data Exchange (ETDEWEB)

Galindo-Nava, E.I., E-mail: eg375@cam.ac.uk; Rae, C.M.F.

2016-01-10

A new approach for modelling dislocation creep during primary and secondary creep in FCC metals is proposed. The Orowan equation and dislocation behaviour at the grain scale are revisited to include the effects of different microstructures such as the grain size and solute atoms. Dislocation activity is proposed to follow a jog-diffusion law. It is shown that the activation energy for cross-slip E{sub cs} controls dislocation mobility and the strain increments during secondary creep. This is confirmed by successfully comparing E{sub cs} with the experimentally determined activation energy during secondary creep in 5 FCC metals. It is shown that the inverse relationship between the grain size and dislocation creep is attributed to the higher number of strain increments at the grain level dominating their magnitude as the grain size decreases. An alternative approach describing solid solution strengthening effects in nickel alloys is presented, where the dislocation mobility is reduced by dislocation pinning around solute atoms. An analysis on the solid solution strengthening effects of typical elements employed in Ni-base superalloys is also discussed. The model results are validated against measurements of Cu, Ni, Ti and 4 Ni-base alloys for wide deformation conditions and different grain sizes.

Lattice design and beam optics calculations for the new large-scale electron-positron collider FCC-ee

CERN Document Server

Haerer, Bastian; Prof. Dr. Schmidt, Ruediger; Dr. Holzer, Bernhard

Following the recommendations of the European Strategy Group for High Energy Physics, CERN launched the Future Circular Collider Study (FCC) to investigate the feasibility of large-scale circular colliders for future high energy physics research. This thesis presents the considerations taken into account during the design process of the magnetic lattice in the arc sections of the electron-positron version FCC-ee. The machine is foreseen to operate at four different centre-of-mass energies in the range of 90 to 350 GeV. Different beam parameters need to be achieved for every energy, which requires a flexible lattice design in the arc sections. Therefore methods to tune the horizontal beam emittance without re-positioning machine components are implemented. In combination with damping and excitation wigglers a precise adjustment of the emittance can be achieved. A very first estimation of the vertical emittance arising from lattice imperfections is performed. Special emphasis is put on the optimisation of the ...

Total Positivity of the Cubic Trigonometric Bézier Basis

Directory of Open Access Journals (Sweden)

Xuli Han

2014-01-01

Full Text Available Within the general framework of Quasi Extended Chebyshev space, we prove that the cubic trigonometric Bézier basis with two shape parameters λ and μ given in Han et al. (2009 forms an optimal normalized totally positive basis for λ,μ∈(-2,1]. Moreover, we show that for λ=-2 or μ=-2 the basis is not suited for curve design from the blossom point of view. In order to compute the corresponding cubic trigonometric Bézier curves stably and efficiently, we also develop a new corner cutting algorithm.

Preliminary Design Study of a Pre-booster Damping Ring for the FCC e+e− Injector

CERN Document Server

Etisken, O; Papaphilippou, Y

2017-01-01

The aim of the FCC e+e− lepton collider is to collide particles in the energy range 40–175 GeV. The FCC e+e− injector complex needs to produce and transport high-intensity e+e− beams at a fast repetition rate of about 0.1 Hz to top up the collider at its collision energy. A basic parameter set exists for all collider energies, assuming a 10 GeV linac operating with a large number of bunches accumulating in the existing SPS, which serves as pre-accelerator and damping ring before the bunches are transferred to the high-energy booster. The purpose of this study is to provide the conceptual design of an alternative damping and accelerator ring, replacing the SPS in the current scheme. This ring will have an injection energy of around 6 GeV and an extraction energy of around 20 GeV. Apart from establishing the basic ring parameters, the final study will include the optics design and layout, and single particle linear and non-linear dynamics optimization, including magnetic and alignment error tolerances. ...

Monitoring of mass flux of catalyst FCC in a Cold Pilot Unit by gamma radiation transmission; Monitoramento da taxa de fluxo do catalisador FCC em uma unidade piloto a frio por medicao de transmissao gama

Energy Technology Data Exchange (ETDEWEB)

Brito, Marcio Fernando Paixao de

2014-09-01

This paper proposes a model for monitoring the mass flow of catalyst FCC - Fluid Catalytic Cracking - in a CPU - Cold Pilot unit - due to the injection of air and solid by gamma radiation transmission. The CPU simplifies the process of FCC, which is represented by the catalyst cycle, and it was constructed of acrylic, so that the flow can be visualized. The CPU consists of riser separation chamber and return column, and simulates the riser reactor of the FCC process. The catalyst is injected into the column back to the base of the riser, an inclined tube, where the compressed air means that there fluidization along the riser. When the catalyst comes in the separation chamber, the solid phase is sent to the return column, and the gas phase exits the system through one of the four cyclones at the top of the separation chamber. The transmission gamma of measures will be made by means of three test sections that have source and detector shielded. Pressure drop in the riser measurements are made through three pressure gauges positioned on the riser. The source used was Am-241 gamma ray with energy of 60 keV, and detector used was a scintillator of NaI (Tl) of 2 {sup x} 2{sup .} Measures the mass flow of catalyst are made by varying the seal of the catalyst, and density of solid in the riser because with the combination of these measures can determine the speed of the catalyst in the riser. The results show that the transmission gamma is a suitable technique for monitoring the flow of catalyst, flow model in CPU is annular, tomography third generation is more appropriate to study the CPU and the density variation in circulation in the CPU decreases linearly with increasing air flow. (author)

INVESTIGATION OF CURVES SET BY CUBIC DISTRIBUTION OF CURVATURE

Directory of Open Access Journals (Sweden)

S. A. Ustenko

2014-03-01

Full Text Available Purpose. Further development of the geometric modeling of curvelinear contours of different objects based on the specified cubic curvature distribution and setpoints of curvature in the boundary points. Methodology. We investigate the flat section of the curvilinear contour generating under condition that cubic curvature distribution is set. Curve begins and ends at the given points, where angles of tangent slope and curvature are also determined. It was obtained the curvature equation of this curve, depending on the section length and coefficient c of cubic curvature distribution. The analysis of obtained equation was carried out. As well as, it was investigated the conditions, in which the inflection points of the curve are appearing. One should find such an interval of parameter change (depending on the input data and the section length, in order to place the inflection point of the curvature graph outside the curve section borders. It was determined the dependence of tangent slope of angle to the curve at its arbitrary point, as well as it was given the recommendations to solve a system of integral equations that allow finding the length of the curve section and the coefficient c of curvature cubic distribution. Findings. As the result of curves research, it is found that the criterion for their selection one can consider the absence of inflection points of the curvature on the observed section. Influence analysis of the parameter c on the graph of tangent slope angle to the curve showed that regardless of its value, it is provided the same rate of angle increase of tangent slope to the curve. Originality. It is improved the approach to geometric modeling of curves based on cubic curvature distribution with its given values at the boundary points by eliminating the inflection points from the observed section of curvilinear contours. Practical value. Curves obtained using the proposed method can be used for geometric modeling of curvilinear

Bicontinuous liquid crystals

CERN Document Server

Lynch, Mathew L

2005-01-01

PrefaceIntroduction AcknowledgmentsBicontinuous Cubic Liquid Crystalline Materials: A Historical Perspective and Modern Assessment; Kr̄e LarssonIntermediate Phases; Michael C. Holmes and Marc S. LeaverCubic Phases and Human Skin: Theory and Practice; Steven Hoath and Lars NorlňThe Relationship between Bicontinuous Inverted Cubic Phases and Membrane Fusion; D.P. SiegelAspects of the Differential Geometry and Topology of Bicontinuous Liquid-Crystalline Phases; Robert W. CorkeryNovel L3 Phases and Their Macroscopic Properties; R. Beck and H. HoffmannBicontinuous Cubic Phases of Lipids with Entra

Catalytic cracking of vacuum gasoil overSVR, ITH, and MFI zeolites as FCC catalyst additives

Czech Academy of Sciences Publication Activity Database

Hussain, A. I.; Palani, A.; Aitani, A. M.; Čejka, Jiří; Shamzhy, Mariya; Kubů, Martin; Al-Khattaf, S. S.

2017-01-01

Roč. 161, JUN 2017 (2017), s. 23-32 ISSN 0378-3820 R&D Projects: GA ČR GBP106/12/G015; GA ČR(CZ) GP14-30898P Institutional support: RVO:61388955 Keywords : ith * mfi * Light olefins * FCC additives Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.752, year: 2016

A local cubic smoothing in an adaptation mode

International Nuclear Information System (INIS)

Dikoussar, N.D.

2001-01-01

A new approach to a local curve approximation and the smoothing is proposed. The relation between curve points is defined using a special cross-ratio weight functions. The coordinates of three curve points are used as parameters for both the weight functions and the tree-point cubic model (TPS). A very simple in computing and stable to random errors cubic smoother in an adaptation mode (LOCUS) is constructed. The free parameter of TPS is estimated independently of the fixed parameters by recursion with the effective error suppression and can be controlled by the cross-ratio parameters. Efficiency and the noise stability of the algorithm are confirmed by examples and by comparison with other known non-parametric smoothers

Phase transformation of metastable cubic γ-phase in U-Mo alloys

International Nuclear Information System (INIS)

Sinha, V.P.; Hegde, P.V.; Prasad, G.J.; Dey, G.K.; Kamath, H.S.

2010-01-01

Over the past decade considerable efforts have been put by many fuel designers to develop low enriched uranium (LEU 235 ) base U-Mo alloy as a potential fuel for core conversion of existing research and test reactors which are running on high enriched uranium (HEU > 85%U 235 ) fuel and also for the upcoming new reactors. U-Mo alloy with minimum 8 wt% molybdenum shows excellent metastability with cubic γ-phase in cast condition. However, it is important to characterize the decomposition behaviour of metastable cubic γ-uranium in its equilibrium products for in reactor fuel performance point of view. The present paper describes the phase transformation behaviour of cubic γ-uranium phase in U-Mo alloys with three different molybdenum compositions (i.e. 8 wt%, 9 wt% and 10 wt%). U-Mo alloys were prepared in an induction melting furnace and characterized by X-ray diffraction (XRD) method for phase determination. Microstructures were developed for samples in as cast condition. The alloys were hot rolled in cubic γ-phase to break the cast structure and then they were aged at 500 o C for 68 h and 240 h, so that metastable cubic γ-uranium will undergo eutectoid decomposition to form equilibrium phases of orthorhombic α-uranium and body centered tetragonal U 2 Mo intermetallic compound. U-Mo alloy samples with different ageing history were then characterized by XRD for phase and development of microstructure.

Estudio de la hidratación de pastas de cemento adicionadas con catalizador de craqueo catalítico usado (FCC de una refinería colombiana

Directory of Open Access Journals (Sweden)

Jenny Johanna Trochez

2010-01-01

Full Text Available En este artículo se analiza el efecto de la incorporación de un residuo industrial de una refinería de petróleo colombiana, conocido como catalizador de craqueo catalítico usado (FCC, en el proceso de hidratación de pastas cementicias. Para tal efecto, se prepararon pastas de cemento Pórtland ordinario (OPC adicionadas en porcentajes del 10 y 20% de FCC como reemplazo de la cantidad de cemento. La reactividad puzolánica del material y el tipo de productos de hidratación se determinó mediante difracción de rayos X (DRX y análisis termogravimétrico (TG/DTG. Adicionalmente, se determinó el calor de hidratación liberado con base en la norma ASTM C186. Los resultados indican que el proceso de hidratación de pastas adicionadas con FCC es altamente exotérmico como consecuencia de su actividad puzolánica a cortas edades. Las fases principales presentes en el proceso de hidratación de las pastas adicionadas con FCC fueron CSH, CAH y CASH, productos similares a los obtenidos en pastas adicionadas con metacaolín.

Lyotropic liquid crystalline phase behaviour in amphiphile-protic ionic liquid systems.

Science.gov (United States)

Chen, Zhengfei; Greaves, Tamar L; Fong, Celesta; Caruso, Rachel A; Drummond, Calum J

2012-03-21

Approximate partial phase diagrams for nine amphiphile-protic ionic liquid (PIL) systems have been determined by synchrotron source small angle X-ray scattering, differential scanning calorimetry and cross polarised optical microscopy. The binary phase diagrams of some common cationic (hexadecyltrimethyl ammonium chloride, CTAC, and hexadecylpyridinium bromide, HDPB) and nonionic (polyoxyethylene (10) oleyl ether, Brij 97, and Pluronic block copolymer, P123) amphiphiles with the PILs, ethylammonium nitrate (EAN), ethanolammonium nitrate (EOAN) and diethanolammonium formate (DEOAF), have been studied. The phase diagrams were constructed for concentrations from 10 wt% to 80 wt% amphiphile, in the temperature range 25 °C to >100 °C. Lyotropic liquid crystalline phases (hexagonal, cubic and lamellar) were formed at high surfactant concentrations (typically >50 wt%), whereas at thermal stability of the phases formed by these surfactants persisted to temperatures above 100 °C. The phase behaviour of amphiphile-PIL systems was interpreted by considering the PIL cohesive energy, liquid nanoscale order, polarity and ionicity. For comparison the phase behaviour of the four amphiphiles was also studied in water.

Cubic Invariant Spherical Surface Harmonics in Conjunction With Diffraction Strain Pole-Figures

NARCIS (Netherlands)

Brakman, C.M.

1986-01-01

Four kinds of cubic invariant spherical surface harmonics are introduced. It has been shown previously that these harmonics occur in the equations relating measured diffraction (line-shift) elastic strain and macro-stresses generating these strains for the case of textured cubic materials. As a

Study of the cubic - to - monoclinic transformation in magnesia partially stabilized zirconia

International Nuclear Information System (INIS)

Muccillo, R.

1988-01-01

The transformation of the cubic phase to the stable monoclinic phase in ZrO 2 : 3%MgO quenched from 1450 0 C to RT has been studied by X-ray diffractometry in order to explain the thermal hysteresis in the electrical conductivity. The monoclinic-to-cubic ratio has been measured for samples annealed in the 500 0 C-1000 0 C temperature range. The results show that the decrease in the cubic phase content is the main responsible for the thermal hysteresis in the electrical conductivity of the magnesia partially stabilized zirconia solid electrolytes. (author) [pt

Bond-order potential for magnetic body-centered-cubic iron and its transferability

Science.gov (United States)

Lin, Yi-Shen; Mrovec, M.; Vitek, V.

2016-06-01

We derived and thoroughly tested a bond-order potential (BOP) for body-centered-cubic (bcc) magnetic iron that can be employed in atomistic calculations of a broad variety of crystal defects that control structural, mechanical, and thermodynamic properties of this technologically important metal. The constructed BOP reflects correctly the mixed nearly free electron and covalent bonding arising from the partially filled d band as well as the ferromagnetism that is actually responsible for the stability of the bcc structure of iron at low temperatures. The covalent part of the cohesive energy is determined within the tight-binding bond model with the Green's function of the Schrödinger equation determined using the method of continued fractions terminated at a sufficient level of the moments of the density of states. This makes the BOP an O (N ) method usable for very large numbers of particles. Only d d bonds are included explicitly, but the effect of s electrons on the covalent energy is included via their screening of the corresponding d d bonds. The magnetic part of the cohesive energy is included using the Stoner model of itinerant magnetism. The repulsive part of the cohesive energy is represented, as in any tight-binding scheme, by an empirical formula. Its functional form is physically justified by studies of the repulsion in face-centered-cubic (fcc) solid argon under very high pressure where the repulsion originates from overlapping s and p closed-shell electrons just as it does from closed-shell s electrons in transition metals squeezed into the ion core under the influence of the large covalent d bonding. Testing of the transferability of the developed BOP to environments significantly different from those of the ideal bcc lattice was carried out by studying crystal structures and magnetic states alternative to the ferromagnetic bcc lattice, vacancies, divacancies, self-interstitial atoms (SIAs), paths continuously transforming the bcc structure to

Magnetic ground states in nanocuboids of cubic magnetocrystalline anisotropy

Energy Technology Data Exchange (ETDEWEB)

Bonilla, F.J., E-mail: fbonilla@cicenergigune.com; Lacroix, L.-M.; Blon, T., E-mail: thomas.blon@insa-toulouse.fr

2017-04-15

Flower and easy-axis vortex states are well-known magnetic configurations that can be stabilized in small particles. However, <111> vortex (V<111>), i.e. a vortex state with its core axis along the hard-axis direction, has been recently evidenced as a stable configuration in Fe nanocubes of intermediate sizes in the flower/vortex transition. In this context, we present here extensive micromagnetic simulations to determine the different magnetic ground states in ferromagnetic nanocuboids exhibiting cubic magnetocrystalline anisotropy (MCA). Focusing our study in the single-domain/multidomain size range (10–50 nm), we showed that V<111> is only stable in nanocuboids exhibiting peculiar features, such as a specific size, shape and magnetic environment, contrarily to the classical flower and easy-axis vortex states. Thus, to track experimentally these V<111> states, one should focused on (i) nanocuboids exhibiting a nearly perfect cubic shape (size distorsion <12%) made of (ii) a material which combines a zero or positive MCA and a high saturation magnetization, such as Fe or FeCo; and (iii) a low magnetic field environment, V<111> being only observed in virgin or remanent states. - Highlights: • The <111> vortex is numerically determined in nanocubes of cubic anisotropy. • It constitutes an intermediate state in the single-domain limit. • Such a vortex can only be stabilized in perfect or slightly deformed nanocuboids. • It exists in nanocuboids made of materials with zero or positive cubic anisotropy. • The associated magnetization reversal is described by a rotation of the vortex axis.

Microstructural origins of high strength and high ductility in an AlCoCrFeNi2.1 eutectic high-entropy alloy

International Nuclear Information System (INIS)

Gao, Xuzhou; Lu, Yiping; Zhang, Bo; Liang, Ningning; Wu, Guanzhong; Sha, Gang; Liu, Jizi; Zhao, Yonghao

2017-01-01

Recent studies indicate that eutectic high-entropy alloys can simultaneously possess high strength and high ductility, which have potential applications in industrial fields. Nevertheless, microstructural origins of the excellent strength–ductility combination remain unclear. In this study, an AlCoCrFeNi 2.1 eutectic high-entropy alloy was prepared with face-centered cubic (FCC)(L1 2 )/body-centered-cubic (BCC)(B2) modulated lamellar structures and a remarkable combination of ultimate tensile strength (1351 MPa) and ductility (15.4%) using the classical casting technique. Post-deformation transmission electron microscopy revealed that the FCC(L1 2 ) phase was deformed in a matter of planar dislocation slip, with a slip system of {111} <110>, and stacking faults due to low stacking fault energy. Due to extreme solute drag, high densities of dislocations are distributed homogeneously at {111} slip plane. In the BCC(B2) phase, some dislocations exist on two {110} slip bands. The atom probe tomography analysis revealed a high density of Cr-enriched nano-precipitates, which strengthened the BCC(B2) phase by Orowan mechanisms. Fracture surface observation revealed a ductile fracture in the FCC(L1 2 ) phase and a brittle-like fracture in the BCC(B2) lamella. The underlying mechanism for the high strength and high ductility of AlCoCrFeNi 2.1 eutectic high-entropy alloy was finally analyzed based on the coupling between the ductile FCC(L1 2 ) and brittle BCC(B2) phases.

Nanostructured cobalt powders synthesised by polyol process and consolidated by Spark Plasma Sintering: Microstructure and mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Fellah, F.; Schoenstein, F.; Dakhlaoui-Omrani, A.; Cherif, S.M.; Dirras, G.; Jouini, N., E-mail: jouini@univ-paris13.fr

2012-07-15

Bulk nanostructured cobalt was processed using a bottom-up strategy. Nanostructured particle agglomerates of about 50 and 240 nm in diameter were synthesised using a polyol route and subsequently consolidated by Spark Plasma Sintering (SPS). The microstructure of the starting powders and of the processed bulk samples was studied and characterised by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns of the as-prepared powders showed predominantly a face centred cubic (fcc) crystalline phase, whereas both fcc and hexagonal close packed (hcp) phases were found within the consolidated samples. A sample with the highest relative mass density (94.5%) was obtained from the small powder particles. TEM observations revealed a lamellar substructure with a high density of nanotwins and stacking faults in every grain in the sample with the highest density. Brillouin light scattering (BLS) and quasistatic compression tests were used to investigate the mechanical properties of the consolidated samples. The two techniques yielded Young modulus values of 168 GPa and 130 GPa, respectively, in the sample with the highest density. This sample also exhibited a yield stress higher than 1 GPa after the compression test, which is mainly attributed to the lamellar-like structure occurring in almost every grain of the polycrystalline aggregate. - Highlights: Black-Right-Pointing-Pointer Cobalt nanoparticles produced by the polyol process present mainly the fcc metastable phase. Black-Right-Pointing-Pointer Bulk nanostructured cobalt is obtained from the nano-particles by Spark Plasma Sintering consolidation. Black-Right-Pointing-Pointer Nanotwins and stacking faults are present in every grain of the more dense sample. Black-Right-Pointing-Pointer Yield strength and plastic domain may be varied depending on the nanoparticle size and the porosity of the consolidated material.

Structural state diagram of concentrated suspensions of jammed soft particles in oscillatory shear flow

Science.gov (United States)

Khabaz, Fardin; Cloitre, Michel; Bonnecaze, Roger T.

2018-03-01

In a recent study [Khabaz et al., Phys. Rev. Fluids 2, 093301 (2017), 10.1103/PhysRevFluids.2.093301], we showed that jammed soft particle glasses (SPGs) crystallize and order in steady shear flow. Here we investigate the rheology and microstructures of these suspensions in oscillatory shear flow using particle-dynamics simulations. The microstructures in both types of flows are similar, but their evolutions are very different. In both cases the monodisperse and polydisperse suspensions form crystalline and layered structures, respectively, at high shear rates. The crystals obtained in the oscillatory shear flow show fewer defects compared to those in the steady shear. SPGs remain glassy for maximum oscillatory strains less than about the yield strain of the material. For maximum strains greater than the yield strain, microstructural and rheological transitions occur for SPGs. Polydisperse SPGs rearrange into a layered structure parallel to the flow-vorticity plane for sufficiently high maximum shear rates and maximum strains about 10 times greater than the yield strain. Monodisperse suspensions form a face-centered cubic (FCC) structure when the maximum shear rate is low and hexagonal close-packed (HCP) structure when the maximum shear rate is high. In steady shear, the transition from a glassy state to a layered one for polydisperse suspensions included a significant induction strain before the transformation. In oscillatory shear, the transformation begins to occur immediately and with different microstructural changes. A state diagram for suspensions in large amplitude oscillatory shear flow is found to be in close but not exact agreement with the state diagram for steady shear flow. For more modest amplitudes of around one to five times the yield strain, there is a transition from a glassy structure to FCC and HCP crystals, at low and high frequencies, respectively, for monodisperse suspensions. At moderate frequencies, the transition is from glassy to HCP via

The sintering behavior of close-packed spheres

DEFF Research Database (Denmark)

Bjørk, Rasmus; Tikare, V.; Frandsen, Henrik Lund

2012-01-01

The sintering behavior of close-packed spheres is investigated using a numerical model. The investigated systems are the body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed spheres (hcp). The sintering behavior is found to be ideal, with no grain growth until full dens...... density is reached for all systems. During sintering, the grains change shape from spherical to tetrakaidecahedron, similar to the geometry analyzed by Coble [R.L. Coble, J. Appl. Phys. 32 (1961) 787]....

Neutron diffraction study of cubic titanium carbohydride at the homogeneity lower limit

International Nuclear Information System (INIS)

Khidirov, I.; Mirzaev, B.B.; Mukhtarova, N.N.

2004-01-01

Cubic carbohydride TiC 0.47H0.22 was prepared by means of quenching from 1200 deg.C followed by the heat treatment using special regime for preventing the hydrogen yield out the lattice. It is shown that at the lower limit of homogeneity range of the cubic carbohydride, hydrogen atoms occupy the tetrahedral interstices 8(c) of the disordered cubic structure with space group of Fm3m. It is found that carbon and hydrogen atoms are partially ordered by annealing at 900-700 deg.C. The ordered structure is face-centred cubic lattice with the parameter a ≅2a 0 , where a 0 is the lattice parameter in disordered structure. The crystal structure of the disordered phase is described within the framework of space group Fd3m, where the carbon atoms occupy mainly (70%) octahedral interstices 16(c) and another ones of carbon and all hydrogen atoms occupy the octahedral interstices 16(d). (author)