WorldWideScience

Sample records for carbon-containing polyhedral boron-cluster

  1. Stealth Amphiphiles: Self-Assembly of Polyhedral Boron Clusters.

    Science.gov (United States)

    Ďorďovič, Vladimír; Tošner, Zdeněk; Uchman, Mariusz; Zhigunov, Alexander; Reza, Mehedi; Ruokolainen, Janne; Pramanik, Goutam; Cígler, Petr; Kalíková, Květa; Gradzielski, Michael; Matějíček, Pavel

    2016-07-01

    This is the first experimental evidence that both self-assembly and surface activity are common features of all water-soluble boron cluster compounds. The solution behavior of anionic polyhedral boranes (sodium decaborate, sodium dodecaborate, and sodium mercaptododecaborate), carboranes (potassium 1-carba-dodecaborate), and metallacarboranes {sodium [cobalt bis(1,2-dicarbollide)]} was extensively studied, and it is evident that all the anionic boron clusters form multimolecular aggregates in water. However, the mechanism of aggregation is dependent on size and polarity. The series of studied clusters spans from a small hydrophilic decaborate-resembling hydrotrope to a bulky hydrophobic cobalt bis(dicarbollide) behaving like a classical surfactant. Despite their pristine structure resembling Platonic solids, the nature of anionic boron cluster compounds is inherently amphiphilic-they are stealth amphiphiles. PMID:27287067

  2. Boron clusters in luminescent materials.

    Science.gov (United States)

    Mukherjee, Sanjoy; Thilagar, Pakkirisamy

    2016-01-21

    In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed. PMID:26574714

  3. Simulation of swift boron clusters traversing amorphous carbon foils

    OpenAIRE

    Heredia Ávalos, Santiago; Abril Sánchez, Isabel; Denton Zanello, Cristian D.; García Molina, Rafael

    2007-01-01

    We use a simulation code to study the interaction of swift boron clusters (Bn+, n=2–6, 14) with amorphous carbon foils. We analyze different aspects of this interaction, such as the evolution of the cluster structure inside the target, the energy and angle distributions at the detector or the stopping power ratio. Our simulation code follows in detail the motion of the cluster fragments through the target and in the vacuum until reaching a detector, taking into account the following interacti...

  4. Boron Clusters as Highly Stable Magnesium-Battery Electrolytes**

    OpenAIRE

    Carter, Tyler J; Mohtadi, Rana; Arthur, Timothy S; Mizuno, Fuminori; Zhang, Ruigang; Shirai, Soichi; Kampf, Jeff W.

    2014-01-01

    Boron clusters are proposed as a new concept for the design of magnesium-battery electrolytes that are magnesium-battery-compatible, highly stable, and noncorrosive. A novel carborane-based electrolyte incorporating an unprecedented magnesium-centered complex anion is reported and shown to perform well as a magnesium-battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium-battery electro...

  5. Indirect photometric detection of boron cluster anions electrophoretically separated in methanol

    Czech Academy of Sciences Publication Activity Database

    Vítová, Lada; Fojt, Lukáš; Vespalec, Radim

    2014-01-01

    Roč. 1338, APR 2014 (2014), s. 174-183. ISSN 0021-9673 Institutional support: RVO:68081707 Keywords : Boron cluster * Capillary electrophoresis * Indirect photometry Subject RIV: BO - Biophysics Impact factor: 4.169, year: 2014

  6. Comparative study on the spectral properties of boron clusters Bn 0/−1(n = 38–40)

    OpenAIRE

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Sun, Guangyu; Qin, Shuijie

    2016-01-01

    The all-boron fullerenes B40 −1 and B39 −1 discovered in recent experiments are characterized and revealed using photoelectron spectroscopy. Except for the photoelectron spectroscopy, one may identify such boron clusters with other spectroscopic techniques, such as infrared spectra and Raman spectra. Insight into the spectral properties of boron clusters is important to understand the boron clusters and find their potential applications. In this work, density functional theory (DFT) and time-...

  7. Guided basin-hopping search of small boron clusters with density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Wei Chun; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melacca Campus, 75450 Melaka (Malaysia)

    2015-04-24

    The search for the ground state structures of Boron clusters has been a difficult computational task due to the unique metalloid nature of Boron atom. Previous research works had overcome the problem in the search of the Boron ground-state structures by adding symmetry constraints prior to the process of locating the local minima in the potential energy surface (PES) of the Boron clusters. In this work, we shown that, with the deployment of a novel computational approach that incorporates density functional theory (DFT) into a guided global optimization search algorithm based on basin-hopping, it is possible to directly locate the local minima of small Boron clusters in the PES at the DFT level. The ground-state structures search algorithm as proposed in this work is initiated randomly and needs not a priori symmetry constraint artificially imposed throughout the search process. Small sized Boron clusters so obtained compare well to the results obtained by similar calculations in the literature. The electronic properties of each structures obtained are calculated within the DFT framework.

  8. Chiral separability of hydrophobic boron cluster anions with native cyclodextrins in water-methanol background electrolytes

    Czech Academy of Sciences Publication Activity Database

    Horáková, Hana; Vespalec, Radim

    2007-01-01

    Roč. 28, č. 20 (2007), s. 3639-3649. ISSN 0173-0835 R&D Projects: GA AV ČR IAA400310613 Institutional research plan: CEZ:AV0Z40310501 Keywords : boron cluster compound * capillary electrophoresis * chiral separation Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.609, year: 2007

  9. Poly(ethylene oxide) containing systems for drug dellivery of boron cluster compounds

    Czech Academy of Sciences Publication Activity Database

    Matějíček, P.; Uchman, M.; Dordovic, V.; Tosner, Z.; Procházka, K.; Brus, Jiří; Zhigunov, Alexander; Pleštil, Josef; Cígler, Petr; Lepšík, Martin

    Prague: Institute of Macromolecular Chemistry AS CR, 2012. s. 74. ISBN 978-80-85009-72-9. [Prague Meeting on Macromolecules /76./ - Polymers in Medicine. 01.07.2012-05.07.2012, Prague] R&D Projects: GA AV ČR IAAX00320901 Institutional research plan: CEZ:AV0Z40550506 Institutional support: RVO:61389013 ; RVO:61388963 Keywords : boron cluster * HIV protease Subject RIV: CA - Inorganic Chemistry

  10. Comparative study on the spectral properties of boron clusters Bn0/‑1(n = 38–40)

    Science.gov (United States)

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Sun, Guangyu; Qin, Shuijie

    2016-04-01

    The all-boron fullerenes B40‑1 and B39‑1 discovered in recent experiments are characterized and revealed using photoelectron spectroscopy. Except for the photoelectron spectroscopy, one may identify such boron clusters with other spectroscopic techniques, such as infrared spectra and Raman spectra. Insight into the spectral properties of boron clusters is important to understand the boron clusters and find their potential applications. In this work, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to comparatively study the vibrational frequencies, infrared spectra, Raman spectra and electronic absorption spectra of boron clusters Bn0/‑1(n = 38–40). The numerical simulations show that such boron clusters have different and meaningful spectral features. These spectral features are readily compared with future spectroscopy measurements and can be used as fingerprints to distinguish the boron clusters Bn0/‑1 with different structures (cage structure or quasi-planar structure) and with different sizes (n = 38–40).

  11. Comparative study on the spectral properties of boron clusters Bn0/−1(n = 38–40)

    Science.gov (United States)

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Sun, Guangyu; Qin, Shuijie

    2016-01-01

    The all-boron fullerenes B40−1 and B39−1 discovered in recent experiments are characterized and revealed using photoelectron spectroscopy. Except for the photoelectron spectroscopy, one may identify such boron clusters with other spectroscopic techniques, such as infrared spectra and Raman spectra. Insight into the spectral properties of boron clusters is important to understand the boron clusters and find their potential applications. In this work, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to comparatively study the vibrational frequencies, infrared spectra, Raman spectra and electronic absorption spectra of boron clusters Bn0/−1(n = 38–40). The numerical simulations show that such boron clusters have different and meaningful spectral features. These spectral features are readily compared with future spectroscopy measurements and can be used as fingerprints to distinguish the boron clusters Bn0/−1 with different structures (cage structure or quasi-planar structure) and with different sizes (n = 38–40). PMID:27113504

  12. Comparative study on the spectral properties of boron clusters Bn(0/-1)(n = 38-40).

    Science.gov (United States)

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Sun, Guangyu; Qin, Shuijie

    2016-01-01

    The all-boron fullerenes B40(-1) and B39(-1) discovered in recent experiments are characterized and revealed using photoelectron spectroscopy. Except for the photoelectron spectroscopy, one may identify such boron clusters with other spectroscopic techniques, such as infrared spectra and Raman spectra. Insight into the spectral properties of boron clusters is important to understand the boron clusters and find their potential applications. In this work, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to comparatively study the vibrational frequencies, infrared spectra, Raman spectra and electronic absorption spectra of boron clusters Bn(0/-1)(n = 38-40). The numerical simulations show that such boron clusters have different and meaningful spectral features. These spectral features are readily compared with future spectroscopy measurements and can be used as fingerprints to distinguish the boron clusters Bn(0/-1) with different structures (cage structure or quasi-planar structure) and with different sizes (n = 38-40). PMID:27113504

  13. Space-filling polyhedral sorbents

    Science.gov (United States)

    Haaland, Peter

    2016-06-21

    Solid sorbents, systems, and methods for pumping, storage, and purification of gases are disclosed. They derive from the dynamics of porous and free convection for specific gas/sorbent combinations and use space filling polyhedral microliths with facial aplanarities to produce sorbent arrays with interpenetrating interstitial manifolds of voids.

  14. Structure of boron clusters revisited, Bn with n = 14-20

    Science.gov (United States)

    Tai, Truong Ba; Tam, Nguyen Minh; Nguyen, Minh Tho

    2012-03-01

    We reinvestigate the structures of neutral boron clusters Bn, with n = 14-20. G3B3 calculations confirm that a transition between 2D and 3D shape occurs at B20, which has a tubular form. In disagreement with Boustani et al. (Phys. Rev. B, 83 (2011) 193405), we find a planar B19 cluster. Standard heats of formation are obtained and used to evaluate the clusters stability. The average binding energy tends to increase with increasing size toward a limit. Higher stability is found B14, B16, B18 and B20. All Bn have negative NICS-values. The bonding nature and electron delocalization of B20 are re-examined using CMO and LOL.

  15. Hydrogen hosting on aluminum-doped boron clusters: Density functional theory

    Science.gov (United States)

    Böyükata, Mustafa; Güvenç, Ziya B.

    2009-11-01

    The geometries, stabilities, and energetics of aluminum doped boron clusters, up to 13-atom, and their various hydrogenated complexes have been investigated via the density functional theory (DFT). The geometry optimizations have been carried out by using B3LYP functional and 6-311++G11 basis set. Up to 5-atom clusters arrangements of the atoms, in the most stable structures, have two-dimensional forms. From 6- to 13-atom clusters three-dimensional forms are favored by the lowest energy structures. Hydrogen hosting effects the structures of AlBn clusters. Adding an Al atom to the cage B12 leads structural changes but hydrogenated boron, B12H12 can resist to Al effect.

  16. Nonadiabtic electron dynamics in densely quasidegenerate states in highly excited boron cluster.

    Science.gov (United States)

    Yonehara, Takehiro; Takatsuka, Kazuo

    2016-04-28

    Following the previous study on nonadiabatic reaction dynamics including boron clusters [T. Yonehara and K. Takatsuka, J. Chem. Phys. 137, 22A520 (2012)], we explore deep into highly excited electronic states of the singlet boron cluster (B12) to find the characteristic features of the densely quasi-degenerate electronic state manifold, which undergo very frequent nonadiabatic transitions and thereby intensive electronic state mixing among very many of the relevant states. So much so, isolating the individual adiabatic states and tracking the expected potential energy surfaces both lose the physical sense. This domain of molecular situation is far beyond the realm of the Born-Oppenheimer approximation. To survey such a violent electronic state-mixing, we apply a method of nonadiabatic electron wavepacket dynamics, the semiclassical Ehrenfest method. We have tracked those electron wavepackets and found the electronic state mixing looks like an ultrafast diffusion in the Hilbert space, which results in huge fluctuation. Furthermore, due to such a violent mixing, the quantum phases associated with the electronic states are swiftly randomized, and consequently the coherence among the electronic states are lost quickly. Besides, these highly excited states are mostly of highly poly-radical nature, even in the spin singlet manifold and the number of radicals amounts up to 10 electrons in the sense of unpaired electrons. Thus the electronic states are summarized to be poly-radical and decoherent with huge fluctuation in shorter time scales of vibrational motions. The present numerical study sets a theoretical foundation for unknown molecular properties and chemical reactivity of such densely quasi-degenerate chemical species. PMID:27131547

  17. Boron Clusters as a Platform for New Materials: Synthesis of Functionalized o-Carborane (C2 B10 H12 ) Derivatives Incorporating DNA Fragments.

    Science.gov (United States)

    Janczak, Slawomir; Olejniczak, Agnieszka; Balabańska, Sandra; Chmielewski, Marcin K; Lupu, Marius; Viñas, Clara; Lesnikowski, Zbigniew J

    2015-10-19

    A synthetic strategy for functionalization of the three vertices of o-carborane and the attachment of the obtained triped to the solid support was developed. Further functionalization of the triped with short DNA sequences by automated DNA synthesis was achieved. The proposed methodology is a first example of boron cluster chemistry on a solid support opening new perspectives in boron cluster functionalization. PMID:26346614

  18. Manganese-centered tubular boron cluster - MnB16-: A new class of transition-metal molecules

    Science.gov (United States)

    Jian, Tian; Li, Wan-Lu; Popov, Ivan A.; Lopez, Gary V.; Chen, Xin; Boldyrev, Alexander I.; Li, Jun; Wang, Lai-Sheng

    2016-04-01

    We report the observation of a manganese-centered tubular boron cluster (MnB16-), which is characterized by photoelectron spectroscopy and ab initio calculations. The relatively simple pattern of the photoelectron spectrum indicates the cluster to be highly symmetric. Ab initio calculations show that MnB16- has a Mn-centered tubular structure with C4v symmetry due to first-order Jahn-Teller effect, while neutral MnB16 reduces to C2v symmetry due to second-order Jahn-Teller effect. In MnB16-, two unpaired electrons are observed, one on the Mn 3dz2 orbital and another on the B16 tube, making it an unusual biradical. Strong covalent bonding is found between the Mn 3d orbitals and the B16 tube, which helps to stabilize the tubular structure. The current result suggests that there may exist a whole class of metal-stabilized tubular boron clusters. These metal-doped boron clusters provide a new bonding modality for transition metals, as well as a new avenue to design boron-based nanomaterials.

  19. On maximum cycle packings in polyhedral graphs

    Directory of Open Access Journals (Sweden)

    Peter Recht

    2014-04-01

    Full Text Available This paper addresses upper and lower bounds for the cardinality of a maximum vertex-/edge-disjoint cycle packing in a polyhedral graph G. Bounds on the cardinality of such packings are provided, that depend on the size, the order or the number of faces of G, respectively. Polyhedral graphs are constructed, that attain these bounds.

  20. On maximum cycle packings in polyhedral graphs

    OpenAIRE

    Peter Recht; Stefan Stehling

    2014-01-01

    This paper addresses upper and lower bounds for the cardinality of a maximum vertex-/edge-disjoint cycle packing in a polyhedral graph G. Bounds on the cardinality of such packings are provided, that depend on the size, the order or the number of faces of G, respectively. Polyhedral graphs are constructed, that attain these bounds.

  1. Polyhedral approach to statistical learning graphical models

    Czech Academy of Sciences Publication Activity Database

    Studený, Milan; Hemmecke, R.; Vomlel, Jiří; Lindner, S.

    Osaka : JST CREST, 2010. s. 1-4. [The 2nd CREST-SBM International Conference "Harmony of Groebner Bases and the Moderm Industrial Socienty". 28.06.2010-02.07.2010, Hotel Hankyu Expo Park, Osaka] Institutional research plan: CEZ:AV0Z10750506 Keywords : Bayesian network * polyhedral approach * imset Subject RIV: BA - General Mathematics http://library.utia.cas.cz/separaty/2010/MTR/studeny-polyhedral approach to statistical learning graphical models.pdf

  2. Simulations of the Structure and Properties of Large Icosahedral Boron Clusters Based on a Novel Semi-Empirical Hamiltonian

    Science.gov (United States)

    Tandy, Paul; Yu, Ming; Jayanthi, C. S.; Wu, Shi-Yu; Condensed Matter Theory Group Team

    2013-03-01

    A successful development of a parameterized semi-empirical Hamiltonian (SCED-LCAO) for boron based on a LCAO framework using a sp3 basis set will be discussed. The semi-empirical Hamiltonian contains environment-dependency and electron screening effects of a many-body Hamiltonian and allows for charge self-consistency. We have optimized the parameters of the SCED-LCAO Hamiltonian for boron by fitting the properties (e.g., the binding energy, bond length, etc.) of boron sheets, small clusters and boron alpha to first-principles calculations based on DFT calculations. Although extended phases of boron alpha and beta have been studied, large clusters of boron with icosahedral structures such as those cut from boron alpha are difficult if not impossible to simulate with ab initio methods. We will demonstrate the effectiveness of the SCED-LCAO Hamiltonian in studying icosahedral boron clusters containing up to 800 atoms and will report on some novel boron clusters and computational speed. Support has been provided by the Dillion Fellowship.

  3. Mesophase behaviour of polyhedral particles

    KAUST Repository

    Agarwal, Umang

    2011-02-13

    Translational and orientational excluded-volume fields encoded in particles with anisotropic shapes can lead to purely entropy-driven assembly of morphologies with specific order and symmetry. To elucidate this complex correlation, we carried out detailed Monte Carlo simulations of six convex space-filling polyhedrons, namely, truncated octahedrons, rhombic dodecahedrons, hexagonal prisms, cubes, gyrobifastigiums and triangular prisms. Simulations predict the formation of various new liquid-crystalline and plastic-crystalline phases at intermediate volume fractions. By correlating these findings with particle anisotropy and rotational symmetry, simple guidelines for predicting phase behaviour of polyhedral particles are proposed: high rotational symmetry is in general conducive to mesophase formation, with low anisotropy favouring plastic-solid behaviour and intermediate anisotropy (or high uniaxial anisotropy) favouring liquid-crystalline behaviour. It is also found that dynamical disorder is crucial in defining mesophase behaviour, and that the apparent kinetic barrier for the liquid-mesophase transition is much lower for liquid crystals (orientational order) than for plastic solids (translational order). © 2011 Macmillan Publishers Limited. All rights reserved.

  4. Polyhedral approach to statistical learning graphical models

    Czech Academy of Sciences Publication Activity Database

    Studený, Milan; Haws, D.; Hemmecke, R.; Lindner, S.

    Singapore : World Scientific Press, 2012, s. 346-372. ISBN 978-981-4383-45-5. [The 2nd CREST-SBM International Conference "Harmony of Groebner Bases and the Modern Industrial Society". Osaka (JP), 28.06.2012-2.07.2012] R&D Projects: GA ČR GA201/08/0539 Institutional support: RVO:67985556 Keywords : Bayesian network stucture * standard imset * characteristic imset * polyhedral geometry Subject RIV: BA - General Mathematics http://library.utia.cas.cz/separaty/2012/MTR/studeny-polyhedral approach to statistical learning graphical models.pdf

  5. Unstructured Polyhedral Mesh Thermal Radiation Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, T.S.; Zika, M.R.; Madsen, N.K.

    2000-07-27

    Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module.

  6. Unstructured Polyhedral Mesh Thermal Radiation Diffusion

    International Nuclear Information System (INIS)

    Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module

  7. Exploiting Polyhedral Symmetries in Social Choice

    CERN Document Server

    Schürmann, Achill

    2011-01-01

    A large amount of literature in social choice theory deals with quantifying the probability of certain election outcomes. One way of computing the probability of a specific voting situation under the impartial anonymous culture is via counting integral points in polyhedra. Here, Ehrhart theory can help, but unfortunately the dimension and complexity of the involved polyhedra grows rapidly with the number of candidates. However, if we exploit available polyhedral symmetries, some computations become possible that previously were infeasible. We show this in three well known examples: Condorcet's paradox, Condorcet efficiency of plurality voting and in Plurality voting vs Plurality Runoff.

  8. Flexible Polyhedral Surfaces with Two Flat Poses

    Directory of Open Access Journals (Sweden)

    Hellmuth Stachel

    2015-05-01

    Full Text Available We present three types of polyhedral surfaces, which are continuously flexible and have not only an initial pose, where all faces are coplanar, but pass during their self-motion through another pose with coplanar faces (“flat pose”. These surfaces are examples of so-called rigid origami, since we only admit exact flexions, i.e., each face remains rigid during the motion; only the dihedral angles vary. We analyze the geometry behind Miura-ori and address Kokotsakis’ example of a flexible tessellation with the particular case of a cyclic quadrangle. Finally, we recall Bricard’s octahedra of Type 3 and their relation to strophoids.

  9. Plasma processing of carbon-containing technical aggregations and wastes

    Science.gov (United States)

    Cherednichenko, V. S.; An'shakov, A. S.; Faleev, V. A.; Danilenko, A. A.

    2008-12-01

    The plasma gasification of technical aggregations is experimentally studied using the utilization of solid domestic wastes as an example. A shaft electric furnace is described, and the experimental and calculated data are analyzed and compared. The high-temperature gasification of carbon-containing wastes is shown to be a promising process.

  10. Interactive volume visualization of general polyhedral grids

    KAUST Repository

    Muigg, Philipp

    2011-12-01

    This paper presents a novel framework for visualizing volumetric data specified on complex polyhedral grids, without the need to perform any kind of a priori tetrahedralization. These grids are composed of polyhedra that often are non-convex and have an arbitrary number of faces, where the faces can be non-planar with an arbitrary number of vertices. The importance of such grids in state-of-the-art simulation packages is increasing rapidly. We propose a very compact, face-based data structure for representing such meshes for visualization, called two-sided face sequence lists (TSFSL), as well as an algorithm for direct GPU-based ray-casting using this representation. The TSFSL data structure is able to represent the entire mesh topology in a 1D TSFSL data array of face records, which facilitates the use of efficient 1D texture accesses for visualization. In order to scale to large data sizes, we employ a mesh decomposition into bricks that can be handled independently, where each brick is then composed of its own TSFSL array. This bricking enables memory savings and performance improvements for large meshes. We illustrate the feasibility of our approach with real-world application results, by visualizing highly complex polyhedral data from commercial state-of-the-art simulation packages. © 2011 IEEE.

  11. Use of boron cluster-containing redox nanoparticles with ROS scavenging ability in boron neutron capture therapy to achieve high therapeutic efficiency and low adverse effects.

    Science.gov (United States)

    Gao, Zhenyu; Horiguchi, Yukichi; Nakai, Kei; Matsumura, Akira; Suzuki, Minoru; Ono, Koji; Nagasaki, Yukio

    2016-10-01

    A boron delivery system with high therapeutic efficiency and low adverse effects is crucial for a successful boron neutron capture therapy (BNCT). In this study, we developed boron cluster-containing redox nanoparticles (BNPs) via polyion complex (PIC) formation, using a newly synthesized poly(ethylene glycol)-polyanion (PEG-polyanion, possessing a (10)B-enriched boron cluster as a side chain of one of its segments) and PEG-polycation (possessing a reactive oxygen species (ROS) scavenger as a side chain of one of its segments). The BNPs exhibited high colloidal stability, selective uptake in tumor cells, specific accumulation, and long retention in tumor tissue and ROS scavenging ability. After thermal neutron irradiation, significant suppression of tumor growth was observed in the BNP-treated group, with only 5-ppm (10)B in tumor tissues, whereas at least 20-ppm (10)B is generally required for low molecular weight (LMW) (10)B agents. In addition, increased leukocyte levels were observed in the LMW (10)B agent-treated group after thermal neutron irradiation, and not in BNP-treated group, which might be attributed to its ROS scavenging ability. No visual metastasis of tumor cells to other organs was observed 1 month after irradiation in the BNP-treated group. These results suggest that BNPs are promising for enhancing the BNCT performance. PMID:27467416

  12. Robust structural identification via polyhedral template matching

    Science.gov (United States)

    Mahler Larsen, Peter; Schmidt, Søren; Schiøtz, Jakob

    2016-06-01

    Successful scientific applications of large-scale molecular dynamics often rely on automated methods for identifying the local crystalline structure of condensed phases. Many existing methods for structural identification, such as common neighbour analysis, rely on interatomic distances (or thresholds thereof) to classify atomic structure. As a consequence they are sensitive to strain and thermal displacements, and preprocessing such as quenching or temporal averaging of the atomic positions is necessary to provide reliable identifications. We propose a new method, polyhedral template matching (PTM), which classifies structures according to the topology of the local atomic environment, without any ambiguity in the classification, and with greater reliability than e.g. common neighbour analysis in the presence of thermal fluctuations. We demonstrate that the method can reliably be used to identify structures even in simulations near the melting point, and that it can identify the most common ordered alloy structures as well. In addition, the method makes it easy to identify the local lattice orientation in polycrystalline samples, and to calculate the local strain tensor. An implementation is made available under a Free and Open Source Software license.

  13. A simple gel electrophoresis method for separating polyhedral gold nanoparticles

    Science.gov (United States)

    Kim, Suhee; Lee, Hye Jin

    2015-07-01

    In this paper, a simple approach to separate differently shaped and sized polyhedral gold nanoparticles (NPs) within colloidal solutions via gel electrophoresis is described. Gel running parameters for separating efficiently gold NPs including gel composition, added surfactant types and applied voltage were investigated. The plasmonic properties and physical structure of the separated NPs extracted from the gel matrix were then investigated using transmission electron microscopy (TEM) and UV-vis spectrophotometry respectively. Data analysis revealed that gel electrophoresis conditions of a 1.5 % agarose gel with 0.1 % sodium dodecyl sulfate (SDS) surfactant under an applied voltage of 100 V resulted in the selective isolation of ~ 50 nm polyhedral shaped gold nanoparticles. Further efforts are underway to apply the method to purify biomolecule-conjugated polyhedral Au NPs that can be readily used for NP-enhanced biosensing platforms.

  14. On generating a diminimal set of polyhedral maps on the torus

    OpenAIRE

    Henry, Jennifer

    2001-01-01

    We develop a method to find a set of diminimal polyhedral maps on the torus from which all other polyhedral maps on the torus may be generated by face splitting and vertex splitting. We employ this method, though not to its completion, to find 53 diminimal polyhedral maps on the Torus.

  15. Self organized locomotion via polyhedral geometry: a minimal example

    CERN Document Server

    Ghosh, Shankar; Bhattacharya, S; Nitsure, Nitin

    2016-01-01

    In this paper we establish a geometrical route to self-organisation. We show that the relevant underlying geometry of the configuration space is a curvilinear polyhedral region. The energetics over the polyhedral region localizes the available space within the close proximity of a corner of this polyhedra. This results into a stronger entrapment of the state which provides it the observed geometrical shape, functionality, and maintains its stability. These theoretical considerations are borne out in the experiments where we study the case of an uphill locomotion of a self organised dumbbell pair placed in a rotating cylinder.

  16. Effect of Carbon Containing Materials on Pure Carbon Reaction-bonded SiC

    Institute of Scientific and Technical Information of China (English)

    JI Xiaoli; WEI Lei; SUN Feng

    2008-01-01

    Petroleum coke, graphite, gas carbon and lower sulfur carbon black were used to prepare reaction-bonded silicon carbide. The influences of different carbon containing materials on properties of carbonaceous precursors, sintering process, and microstructure of the prepared SiC were researched. The results show that:(1)With the density of carbon containing materials increasing, the porosity of carbonaceous precursors decreases and the infiltrating process of liquid silicon is more difficult.(2)The reaction between carbon containing materials and liquid silicon, the volume effect is more obvious with the density of carbon containing materials increasing.(3)As the carbon containing materials density decreasing, residual carbon in reaction bonded SiC also decreases.

  17. Clustered deep shadow maps for integrated polyhedral and volume rendering

    KAUST Repository

    Bornik, Alexander

    2012-01-01

    This paper presents a hardware-accelerated approach for shadow computation in scenes containing both complex volumetric objects and polyhedral models. Our system is the first hardware accelerated complete implementation of deep shadow maps, which unifies the computation of volumetric and geometric shadows. Up to now such unified computation was limited to software-only rendering . Previous hardware accelerated techniques can handle only geometric or only volumetric scenes - both resulting in the loss of important properties of the original concept. Our approach supports interactive rendering of polyhedrally bounded volumetric objects on the GPU based on ray casting. The ray casting can be conveniently used for both the shadow map computation and the rendering. We show how anti-aliased high-quality shadows are feasible in scenes composed of multiple overlapping translucent objects, and how sparse scenes can be handled efficiently using clustered deep shadow maps. © 2012 Springer-Verlag.

  18. Form-finding with polyhedral meshes made simple

    KAUST Repository

    Tang, Chengcheng

    2014-07-27

    We solve the form-finding problem for polyhedral meshes in a way which combines form, function and fabrication; taking care of user-specified constraints like boundary interpolation, planarity of faces, statics, panel size and shape, enclosed volume, and last, but not least, cost. Our main application is the interactive modeling of meshes for architectural and industrial design. Our approach can be described as guided exploration of the constraint space whose algebraic structure is simplified by introducing auxiliary variables and ensuring that constraints are at most quadratic. Computationally, we perform a projection onto the constraint space which is biased towards low values of an energy which expresses desirable "soft" properties like fairness. We have created a tool which elegantly handles difficult tasks, such as taking boundary-alignment of polyhedral meshes into account, planarization, fairing under planarity side conditions, handling hybrid meshes, and extending the treatment of static equilibrium to shapes which possess overhanging parts.

  19. On polyhedral approximations of polytopes for learning Bayesian networks

    Czech Academy of Sciences Publication Activity Database

    Studený, Milan; Haws, D.C.

    2013-01-01

    Roč. 4, č. 1 (2013), s. 59-92. ISSN 1309-3452 R&D Projects: GA ČR GA201/08/0539 Institutional support: RVO:67985556 Keywords : Bayesian network structure * integer programming * standard imset * characteristic imset * LP relaxation Subject RIV: BA - General Mathematics http://library.utia.cas.cz/separaty/2013/MTR/studeny-on polyhedral approximations of polytopes for learning bayesian networks.pdf

  20. Flops and mutations for crepant resolutions of polyhedral singularities

    CERN Document Server

    de Celis, Alvaro Nolla

    2011-01-01

    We prove that any crepant resolution of a polyhedral singularity C^3/G for G a subgroup of SO(3) of types Z/nZ, D_{2n} and T is isomorphic to a moduli space of representations of a quiver with relations. Moreover we classify all crepant resolutions explicitly by giving an open cover and find a one-to-one correspondence between them and mutations of the McKay quiver.

  1. Chelating polyhedral oligomeric silsesquioxane nanofillers in chitosan dialysis membranes

    Czech Academy of Sciences Publication Activity Database

    Tishchenko, Galina; Kebrlová, Natálie; Brus, Jiří; Dybal, Jiří; Rosova, E.; Dmitriev, I.; Elyashevich, G. K.; Bastl, Zdeněk

    Praha : Ústav makromolekulární chemie AS CR, v. v. i, 2007 - (Kahovec, J.). s. 101 ISBN 978-80-85009-55-2. [Microsymposium on Nanostructured Polymers and Polymer Nanocomposites /46./. 08.07.2007-12.07.2007, Praha] R&D Projects: GA ČR GA525/05/2584 Institutional research plan: CEZ:AV0Z40500505 Keywords : chitosan composite dialysis membranes * polyhedral oligomeric silsesquioxanes * metal ions * elastic properties Subject RIV: CD - Macromolecular Chemistry

  2. Final Project Report: A Polyhedral Transformation Framework for Compiler Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Sadayappan, Ponnuswamy [The Ohio State University; Rountev, Atanas [The Ohio State University

    2015-06-15

    The project developed the polyhedral compiler transformation module PolyOpt/Fortran in the ROSE compiler framework. PolyOpt/Fortran performs automated transformation of affine loop nests within FORTRAN programs for enhanced data locality and parallel execution. A FORTAN version of the Polybench library was also developed by the project. A third development was a dynamic analysis approach to gauge vectorization potential within loops of programs; software (DDVec) for automated instrumentation and dynamic analysis of programs was developed.

  3. Highly uniform polyhedral colloids formed by colloidal crystal templating

    Science.gov (United States)

    Wang, Yifan; McGinley, James; Crocker, John; Crocker Research Group Team

    2015-03-01

    We seek to create polyhedral solid particles by trapping oil droplets in a colloidal crystal, and polymerizing them in situ, resulting in polyhedral particles containing spherical dimples in an ordered arrangement. Specifically, highly monodisperse, micron-sized droplets of 3-methacryloxypropyl trimethoxysilane (TPM) were first prepared through a poly condensation reaction, following well established methods. The droplets were mixed with an excess of polystyrene(PS) particles (diameter in 2.58 μm), which formed close packed (FCC or HCP) colloidal crystals by natural sedimentation and compression under partial drying to an extent, with TPM oil droplets trapped into their tetrahedral and octahedral interstitial sites and wet PS particles. Depending on the initial particle volume fraction and extent of drying, a high yield of dimpled particles having different shapes including tetrahedra and cubes were obtained after oil initiated polymerization and dissolution of the host PS particles, as seen under SEM. The effects of TPM to PS particles size ratio, drying time, and other factors in relation to the yield of tetrahedral and cubic dimpled particles will be presented. Finally, fractionation techniques were used to obtain suspensions of uniform polyhedral particles of high purity.

  4. When do the recession cones of a polyhedral complex form a fan?

    CERN Document Server

    Gil, José Ignacio Burgos

    2010-01-01

    We study the problem of when the collection of the recession cones of a polyhedral complex forms also a complex. We exhibit an example showing that this is no always the case. We also show that if the support of the given polyhedral complex satisfies a Minkowski-Weyl type condition, then the answer is positive. As a consequence, we obtain a classification theorem for proper toric schemes over a discrete valuation ring in terms of complete strongly convex rational polyhedral complexes.

  5. On the accuracy of uniform polyhedral approximations of the copositive cone

    OpenAIRE

    Yıldırım, Emre Alper

    2012-01-01

    We consider linear optimization problems over the cone of copositive matrices. Such conic optimization problems, called copositive programs, arise from the reformulation of a wide variety of difficult optimization problems. We propose a hierarchy of increasingly better outer polyhedral approximations to the copositive cone. We establish that the sequence of approximations is exact in the limit. By combining our outer polyhedral approximations with the inner polyhedral approximations due to de...

  6. Form-finding with polyhedral meshes made simple

    KAUST Repository

    Tang, Chengcheng

    2015-08-09

    We solve the form-finding problem for polyhedral meshes in a way which combines form, function and fabrication; taking care of user-specified constraints like boundary interpolation, planarity of faces, statics, panel size and shape, enclosed volume, and cost. Our main application is the interactive modeling of meshes for architectural and industrial design. Our approach can be described as guided exploration of the constraint space whose algebraic structure is simplified by introducing auxiliary variables and ensuring that constraints are at most quadratic.

  7. Hierarchical self-assembly of complex polyhedral microcontainers

    Science.gov (United States)

    Filipiak, David J.; Azam, Anum; Leong, Timothy G.; Gracias, David H.

    2009-07-01

    The concept of self-assembly of a two-dimensional (2D) template to a three-dimensional (3D) structure has been suggested as a strategy to enable highly parallel fabrication of complex, patterned microstructures. We have previously studied the surface-tension-based self-assembly of patterned, microscale polyhedral containers (cubes, square pyramids and tetrahedral frusta). In this paper, we describe the observed hierarchical self-assembly of more complex, patterned polyhedral containers in the form of regular dodecahedra and octahedra. The hierarchical design methodology, combined with the use of self-correction mechanisms, was found to greatly reduce the propagation of self-assembly error that occurs in these more complex systems. It is a highly effective way to mass-produce patterned, complex 3D structures on the microscale and could also facilitate encapsulation of cargo in a parallel and cost-effective manner. Furthermore, the behavior that we have observed may be useful in the assembly of complex systems with large numbers of components.

  8. Al4C3 Hydration Thermochemical Analysis for Burned Carbon-containing Refractories with Al

    Institute of Scientific and Technical Information of China (English)

    YANG Ding'ao; YU Zhiming; FAN Liuwu

    2003-01-01

    In this paper, X-ray diffractogram analysis and SEM observation of Al4 C3 formed at high temperature from carbon-containing refractories with Al have been carried out.Aluminum added to carbon-containing refractories reacts with C(s)to form Al4 C3(s) gradually during heating from 600 ℃ to 1200℃.It is considered that the interlocked structure of Al4 C3 plate crystals promotes the outstanding increase of hot modulus of rupture of carbon-containing refractories with Al. The HMOR of carbon-containing refractories added with Al additive from 0 to 5wt% increases by 2.8 times being from 6.5MPa to 18.2MPa.After a thermochemical calculation for hydration reaction processes of Al4 C3 and H2O(g), the equilibrium partial pressure chart of H2O(g)in H2O-Al4C3-Al(OH)3 system vs various temperatures has been attained . The H2O (g) partial pressure in the air needed for the Al4 C3 hydration reaction is no more than 10~18 atm at the temperature below 120℃.It is considered that the burned carbon-containing refractories with Al is extremely easy to hydrate and the cracking of burned carbon-containing refractories is generated because that the hydration expansion is 2.11 times during transforming from Al4 C3 to Al(OH)3.The fundamental measure against hydration of the refractories is to insulate the refractories from H2O(g)by various means such as pitch impregnation or other sealing materials.

  9. Carbon-containing adsorbents based on fly ash from thermal power plants

    Energy Technology Data Exchange (ETDEWEB)

    Mnushkin, I.I.; Ivanova, L.S.; Grabchak, S.L.; Krichevskaya, G.V. (Institut Fizicheskoi Khimii AN Ukrainy, Kiev (Ukraine))

    1993-01-01

    Studies properties of carbon-containing polymineral systems in fly ash from different power plants. A chemical analysis of fly ash from the Starobeshevskaya power plant in the Ukraine is given. Polymineral systems studied were composed of carbon particles and aluminosilicate. Micropore structure and sorptive properties of 12 samples prepared from fly ash were examined. The samples studied proved to be amphoterous adsorbents with good sorption of both acids and hydroxides. It is shown that carbon-containing fly ash from thermal power plants can be used to neutralize alkaline effluents and treat acidic sewage to remove dissolved fatty acids of C[sub 1]-C[sub 4] fractions. 5 refs.

  10. Ricci Curvature on Polyhedral Surfaces via Optimal Transportation

    Directory of Open Access Journals (Sweden)

    Benoît Loisel

    2014-03-01

    Full Text Available The problem of correctly defining geometric objects, such as the curvature, is a hard one in discrete geometry. In 2009, Ollivier defined a notion of curvature applicable to a wide category of measured metric spaces, in particular to graphs. He named it coarse Ricci curvature because it coincides, up to some given factor, with the classical Ricci curvature, when the space is a smooth manifold. Lin, Lu and Yau and Jost and Liu have used and extended this notion for graphs, giving estimates for the curvature and, hence, the diameter, in terms of the combinatorics. In this paper, we describe a method for computing the coarse Ricci curvature and give sharper results, in the specific, but crucial case of polyhedral surfaces.

  11. Synthesis of conjugates of polyhedral boron compounds with tumor-seeking molecules for neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Bregadze, V., E-mail: bre@ineos.ac.ru [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Str. 28, Moscow 119991 (Russian Federation); Semioshkin, A.; Sivaev, I. [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Str. 28, Moscow 119991 (Russian Federation)

    2011-12-15

    Recent achievements in design and synthesis of boronated acids, amino acids, glycerols as well as conjugates of polyhedral boron hydrides (ortho-carborane, closo-dodecaborate and cobalt bis(dicarbollide)) with natural porphyrins, carbohydrates and nucleosides are described.

  12. Polyhedral Methods for Space Curves Exploiting Symmetry Applied to the Cyclic n-roots Problem

    OpenAIRE

    Adrovic, Danko; Verschelde, Jan

    2011-01-01

    We present a polyhedral algorithm to manipulate positive dimensional solution sets. Using facet normals to Newton polytopes as pretropisms, we focus on the first two terms of a Puiseux series expansion. The leading powers of the series are computed via the tropical prevariety. This polyhedral algorithm is well suited for exploitation of symmetry, when it arises in systems of polynomials. Initial form systems with pretropisms in the same group orbit are solved only once, allowing for a systema...

  13. Materials and Concepts for Full Ceramic SOFCs with Focus on Carbon Containing Fuels

    DEFF Research Database (Denmark)

    Holtappels, Peter; Sudireddy, Bhaskar Reddy; Veltzé, Sune;

    , stability, and S- tolerance has been investigated. These results and an assessment on a 1 kW system level using CPOX reformed natural gas will be reviewed and further perspectives of the cell concept discussed, especially with respect to efficient operation on high carbon containing fuels....... stimulated the development for full ceramic anodes based on strontium titanates. Furthermore, the Ni-cermet is primarily a hydrogen oxidation electrode and efficiency losses might occur when operating on carbon containing fuels. In a recent European project full ceramic cells comprising CGO/Ni infiltrated Nb......-doped SrTiO3 anodes, and LSM/YSZ cathodes have been developed and tested as single 5 x 5 cm2 cells. The initial performance reached 0.4 W/cm2 at 850 °C and redox tolerance has been proven. The cell concept provides flexibility with respect to the used electro catalysts and their impact on power output...

  14. A nanocage for nanomedicine: polyhedral oligomeric silsesquioxane (POSS).

    Science.gov (United States)

    Ghanbari, Hossein; Cousins, Brian G; Seifalian, Alexander M

    2011-07-15

    Ground-breaking advances in nanomedicine (defined as the application of nanotechnology in medicine) have proposed novel therapeutics and diagnostics, which can potentially revolutionize current medical practice. Polyhedral oligomeric silsesquioxane (POSS) with a distinctive nanocage structure consisting of an inner inorganic framework of silicon and oxygen atoms, and an outer shell of organic functional groups is one of the most promising nanomaterials for medical applications. Enhanced biocompatibility and physicochemical (material bulk and surface) properties have resulted in the development of a wide range of nanocomposite POSS copolymers for biomedical applications, such as the development of biomedical devices, tissue engineering scaffolds, drug delivery systems, dental applications, and biological sensors. The application of POSS nanocomposites in combination with other nanostructures has also been investigated including silver nanoparticles and quantum dot nanocrystals. Chemical functionalization confers antimicrobial efficacy to POSS, and the use of polymer nanocomposites provides a biocompatible surface coating for quantum dot nanocrystals to enhance the efficacy of the materials for different biomedical and biotechnological applications. Interestingly, a family of POSS-containing nanocomposite materials can be engineered either as completely non-biodegradable materials or as biodegradable materials with tuneable degradation rates required for tissue engineering applications. These highly versatile POSS derivatives have created new horizons for the field of biomaterials research and beyond. Currently, the application of POSS-containing polymers in various fields of nanomedicine is under intensive investigation with expectedly encouraging outcomes. PMID:21598339

  15. Fast polyhedral cell sorting for interactive rendering of unstructured grids

    Energy Technology Data Exchange (ETDEWEB)

    Combra, J; Klosowski, J T; Max, N; Silva, C T; Williams, P L

    1998-10-30

    Direct volume rendering based on projective methods works by projecting, in visibility order, the polyhedral cells of a mesh onto the image plane, and incrementally compositing the cell's color and opacity into the final image. Crucial to this method is the computation of a visibility ordering of the cells. If the mesh is ''well-behaved'' (acyclic and convex), then the MPVO method of Williams provides a very fast sorting algorithm; however, this method only computes an approximate ordering in general datasets, resulting in visual artifacts when rendered. A recent method of Silva et al. removed the assumption that the mesh is convex, by means of a sweep algorithm used in conjunction with the MPVO method; their algorithm is substantially faster than previous exact methods for general meshes. In this paper we propose a new technique, which we call BSP-XMPVO, which is based on a fast and simple way of using binary space partitions on the boundary elements of the mesh to augment the ordering produced by MPVO. Our results are shown to be orders of magnitude better than previous exact methods of sorting cells.

  16. Carbonate-containing apatite (CAP) synthesis under moderate conditions starting from calcium carbonate and orthophosphoric acid

    International Nuclear Information System (INIS)

    The synthesis of carbonate-containing apatite (CAP) from calcium carbonate and orthophosphoric acid under moderate conditions was investigated. In all cases, complete precipitation of orthophosphate species was observed. The reaction temperature influenced strongly the decomposition of calcium carbonate and therefore the composition of formed products. The reaction temperature of 80 °C was found to be effective for the complete decomposition of calcium carbonate particles after 48 h of reaction. Infra-red spectroscopy (IR), nuclear magnetic resonance (NMR), thermogravimetry/mass spectroscopy (TG–MS) coupling, and X-ray diffraction (XRD) characterizations allowed the identification of the composition of formed products. By increasing the reaction temperature from 20 °C to 80 °C, the content of A-type CAP increased and that of B-type CAP decreased, according to the favorable effect of temperature on the formation of A-type CAP. The total amount of carbonate content incorporated in CAP's structure, which was determined by TG–MS analysis, increased with the reaction temperature and reached up to 4.1% at 80 °C. At this temperature, the solid product was mainly composed of apatitic components and showed the typical flat-needle-like structure of CAP particles obtained in hydrothermal conditions. These results show an interesting one-step synthesis of CAP from calcium carbonate and orthophosphoric acid as low cost but high purity starting materials. Highlights: • The synthesis of carbonate-containing apatites from CaCO3 and H3PO4 was studied. • The decomposition of CaCO3 particles was complete at 80 °C, 13.2 bar for 48 h. • The transformation of CaCO3 and H3PO4 into apatitic products was also complete. • Pure carbonate-containing apatite was directly obtained without water-rising step

  17. Fuel cell components and systems having carbon-containing electrically-conductive hollow fibers

    Energy Technology Data Exchange (ETDEWEB)

    Langry, Kevin C; Farmer, Joseph C

    2015-04-28

    A method, according to one embodiment, includes acquiring a structure having an ionically-conductive, electrically-resistive electrolyte/separator layer covering an inner or outer surface of a carbon-containing electrically-conductive hollow fiber and a catalyst along one side thereof, adding an anode that extends along at least part of a length of the structure, and adding a cathode that extends along at least part of the length of the structure, the cathode being on an opposite side of the hollow fiber as the anode.

  18. Rhenium distribution at high temperature processing of some kinds of carbon-containing raw materials

    International Nuclear Information System (INIS)

    Rhenium distribution at high temperature processing of some kinds of non-conventional potential carbon-containing raw materials (such as shale oil, shungite-containing rocks, high viscosity oil and natural bitumen) is studied. Rhenium concentrating products in semicoking, oxidizing pyrolysis, bertinization and plasma chemical processing of Middle Asian shale oil are revealed. It is established that during semicoking of shale oil, rhenium is concentrating in a solid product (semicoke); during bertinization, oxidizing pyrolysis and plasma chemical processing - in bertinate pyrolysis coke, coke and adsorber nozzle material correspondingly

  19. Emission Inventories of Carbon-containing Greenhouse Gases in and Technological Measures for Their Abatement

    Institute of Scientific and Technical Information of China (English)

    Zhuang Yahui; Zhang Hongxun; Wang Xiaoke; Li Changsheng

    2004-01-01

    The report summarizes surveys on carbon inventories and initiatives on sustainable carbon cycling taken by the Research Center for EcoEnvironmental Sciences, where the authors work/worked. The first part of the report, which appeared in the preceding issue of this journal, deals with the concept of sustainable carbon cycling, the historic evolution of carbon cycling processes in China, carbon pool enhancement, value addition,carbon sequestration and carbon balance. This very paper, as the second part of the report, covers the results of carbon dynamics modeling, emission inventories of various carbon-containing greenhouse gases and their potential abatement measures.

  20. Analysis of the electron density features of small boron clusters and the effects of doping with C, P, Al, Si, and Zn: Magic B7P and B8Si clusters

    Science.gov (United States)

    Saha, P.; Rahane, A. B.; Kumar, V.; Sukumar, N.

    2016-05-01

    Boron atomic clusters show several interesting and unusual size-dependent features due to the small covalent radius, electron deficiency, and higher coordination number of boron as compared to carbon. These include aromaticity and a diverse array of structures such as quasi-planar, ring or tubular shaped, and fullerene-like. In the present work, we have analyzed features of the computed electron density distributions of small boron clusters having up to 11 boron atoms, and investigated the effect of doping with C, P, Al, Si, and Zn atoms on their structural and physical properties, in order to understand the bonding characteristics and discern trends in bonding and stability. We find that in general there are covalent bonds as well as delocalized charge distribution in these clusters. We associate the strong stability of some of these planar/quasiplanar disc-type clusters with the electronic shell closing with effectively twelve delocalized valence electrons using a disc-shaped jellium model. {{{{B}}}9}-, B10, B7P, and B8Si, in particular, are found to be exceptional with very large gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, and these are suggested to be magic clusters.

  1. Hydrogen storage properties of carbon nanomaterials and carbon containing metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Maehlen, Jan Petter

    2003-07-01

    The topic of this thesis is structural investigations of carbon containing materials in respect to their hydrogen storage properties. This work was initially triggered by reports of extremely high hydrogen storage capacities of specific carbon nanostructures. It was decided to try to verify and understand the mechanisms in play in case of the existence of such high hydrogen densities in carbon. Two different routes towards the goal were employed; by studying selected hydrides with carbon as one of its constituents (mainly employing powder diffraction techniques in combination with hydrogen absorption and desorption measurements) and by carefully conducting hydrogen sorption experiments on what was believed to be the most ''promising'' carbon nanomaterial sample. In the latter case, a lot of effort was attributed to characterisations of different carbon nanomaterial containing samples with the aid of electron microscopy. Three different carbon-containing metal hydride systems, Y2C-H, YCoC-H and Y5SiC0.2-H, were examined. A relation between hydrogen occupation and the local arrangement of metal and carbon atoms surrounding the hydrogen sites was established. Several characteristic features of the compounds were noted in addition to solving the structure of the former unknown deuterideY5Si3C0.2D2.0 by the use of direct methods. Several carbon-nanomaterial containing samples were studied by means of transmission electron microscopy and powder diffraction, thus gaining knowledge concerning the structural aspects of nanomaterials. Based on these investigations, a specific sample containing a large amount of open-ended single-wall carbon nanotubes was chosen for subsequent hydrogen storage experiments. The latter experiments revealed moderate hydrogen storage capacities of the nanotubes not exceeding the values obtained for more conventional forms of carbon. These two different routes in investigating the hydrogen storage properties of carbon and

  2. Synthesis and characterization of polyhedral and quasi-sphere non-polyhedral Pt nanoparticles: effects of their various surface morphologies and sizes on electrocatalytic activity for fuel cell applications

    International Nuclear Information System (INIS)

    In this article, polyhedral and non-polyhedral Pt nanoparticles were prepared by modified polyol method using AgNO3 as a good structure-modifying agent. Their TEM and HRTEM images showed the particle size in the range of 8–16 nm for both the above cases. The structures and properties of the surfaces of Pt nanoparticles were investigated through cyclic voltammetry in dilute perchloric acid (HClO4) electrolyte solution. A comparison of the electrocatalytic property in methanol electrooxidation was made. Here, the effects of polyhedral and non-polyhedral morphologies on their catalytic properties were studied. The results revealed that the special catalytic activity of quasi-sphere non-polyhedral Pt nanoparticles is higher than that of polyhedral Pt nanoparticles. In addition, Pt nanoparticles of un-sharp and quasi-sphere morphologies exhibit the tolerance to poisoning species better than that of Pt nanoparticles of sharp and polyhedral morphologies due to the various morphologies of the catalyst surfaces in the chronoamperometric plots. Therefore, these experimental evidences showed the morphology-dependent catalytic property according to the various morphologies and complexity of their catalyst surfaces.

  3. Robust Hinf control of uncertain switched systems defined on polyhedral sets with Filippov solutions

    DEFF Research Database (Denmark)

    Ahmadi, Mohamadreza; Mojallali, Hamed; Wisniewski, Rafal

    2012-01-01

    This paper considers the control problem of a class of uncertain switched systems defined on polyhedral sets known as piecewise linear systems where, instead of the conventional Carathe ́odory solutions, Filippov solutions are studied. In other words, in contrast to the previous studies, solutions...

  4. Polyhedral combinatorics of the cardinality constrained quadratic knapsack problem and the quadratic selective travelling salesman problem

    DEFF Research Database (Denmark)

    Mak, Vicky; Thomadsen, Tommy

    2006-01-01

    hard. The QSTSP and the QKP can be solved using branch-and-cut methods. Good bounds can be obtained if strong constraints are used. Hence it is important to identify strong or even facet-defining constraints. This paper studies the polyhedral combinatorics of the QSTSP and the QKP, i.e. amongst others...

  5. Modeling IrisCode and its variants as convex polyhedral cones and its security implications.

    Science.gov (United States)

    Kong, Adams Wai-Kin

    2013-03-01

    IrisCode, developed by Daugman, in 1993, is the most influential iris recognition algorithm. A thorough understanding of IrisCode is essential, because over 100 million persons have been enrolled by this algorithm and many biometric personal identification and template protection methods have been developed based on IrisCode. This paper indicates that a template produced by IrisCode or its variants is a convex polyhedral cone in a hyperspace. Its central ray, being a rough representation of the original biometric signal, can be computed by a simple algorithm, which can often be implemented in one Matlab command line. The central ray is an expected ray and also an optimal ray of an objective function on a group of distributions. This algorithm is derived from geometric properties of a convex polyhedral cone but does not rely on any prior knowledge (e.g., iris images). The experimental results show that biometric templates, including iris and palmprint templates, produced by different recognition methods can be matched through the central rays in their convex polyhedral cones and that templates protected by a method extended from IrisCode can be broken into. These experimental results indicate that, without a thorough security analysis, convex polyhedral cone templates cannot be assumed secure. Additionally, the simplicity of the algorithm implies that even junior hackers without knowledge of advanced image processing and biometric databases can still break into protected templates and reveal relationships among templates produced by different recognition methods. PMID:23193454

  6. Well-faceted noble-metal nanocrystals with nonconvex polyhedral shapes.

    Science.gov (United States)

    Chen, Qiaoli; Jia, Yanyan; Xie, Shuifen; Xie, Zhaoxiong

    2016-06-01

    Precise engineering of noble-metal nanocrystals (NCs) is not only an important fundamental research topic, but also has great realistic significance in improving their performances required by the poor reserve and high cost of noble metals. Well-faceted noble-metal NCs with nonconvex polyhedral shapes could be promising candidates to optimize their performance and thus minimize their usage, as they may integrate a well-defined surface structure and a large surface area together, enabling them to have outstanding performance and high efficiency of atomic utilization. Moreover, undesirable aggregation and ripening phenomena could be avoided. This review provides a comprehensive summary of the unique characteristics and corresponding models of well-faceted nonconvex polyhedral noble-metal NCs by classifying the cases into four distinct types, namely the concave polyhedral structure, excavated polyhedral structure, branched structure and nanocage structure, respectively. Due to the complexity of nonconvex morphologies and the thermodynamic antipathy for the growth of nonconvex shaped NCs, we firstly demonstrate the structure characterization and synthetic methodology in detail. Subsequently, typical applications in electrocatalysis and plasmonic fields are presented to demonstrate the unique surface and morphological effects generated from the well-faceted nonconvex NCs. To promote further development in this field, the perspectives and challenges concerning well-faceted noble-metal NCs with nonconvex shapes are put forward in the end. PMID:27086861

  7. Direct chemical conversion of graphene to boron- and nitrogen- and carbon-containing atomic layers

    Science.gov (United States)

    Gong, Yongji; Shi, Gang; Zhang, Zhuhua; Zhou, Wu; Jung, Jeil; Gao, Weilu; Ma, Lulu; Yang, Yang; Yang, Shubin; You, Ge; Vajtai, Robert; Xu, Qianfan; MacDonald, Allan H.; Yakobson, Boris I.; Lou, Jun; Liu, Zheng; Ajayan, Pulickel M.

    2014-01-01

    Graphene and hexagonal boron nitride are typical conductor and insulator, respectively, while their hybrids hexagonal boron carbonitride are promising as a semiconductor. Here we demonstrate a direct chemical conversion reaction, which systematically converts the hexagonal carbon lattice of graphene to boron nitride, making it possible to produce uniform boron nitride and boron carbonitride structures without disrupting the structural integrity of the original graphene templates. We synthesize high-quality atomic layer films with boron-, nitrogen- and carbon-containing atomic layers with full range of compositions. Using this approach, the electrical resistance, carrier mobilities and bandgaps of these atomic layers can be tuned from conductor to semiconductor to insulator. Combining this technique with lithography, local conversion could be realized at the nanometre scale, enabling the fabrication of in-plane atomic layer structures consisting of graphene, boron nitride and boron carbonitride. This is a step towards scalable synthesis of atomically thin two-dimensional integrated circuits.

  8. Sorption recovery of 137Cs and 90Sr with carbonate-containing natural mineral tripolite

    International Nuclear Information System (INIS)

    Sorption characteristics of a carbonate-containing mineral (tripolite) were studied on model aqueous solutions and real waste water in a wide range of pH in the presence of isotopic and nonisotopic carriers and organic impurities. Sorption of 137Cs and 90Sr is adequately described by a power function. Analysis of 137Cs sorption isotherms suggests that radiocesium is adsorbed by ion-exchange mechanism, during which Cs+ ions from the solution exchange mainly with bivalent ions of the sorbent, whereas in 90Sr sorption trivalent ions of the sorbent also participate in the process. Saturation capacity of tripolite with respect to cesium and strontium was evaluated to be 0.3 and 1.0 mg-equiv./g respectively

  9. Regeneration of carbon containing sodium dodecylbenzene sulfonate--Cyclic regeneration with steam in fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Umehara, T.; Smith, J.M.

    1984-03-01

    Cyclic regeneration of activated carbon containing adsorbed sodium dodecylbenzene sulfonate (DBS) was studied in fluidized beds at 1119 K and 101.3 kPa. Optimum restorationof adsorption capacity (97.2% per cycle) resulted when gasification with 21.5% steam was continued for 200 s. At that time, about 85% of the DBS added to the carbon during the adsorption process had been removed. Because of the adsorbed inorganic residue from DBS, these results are somewhat different from earlier studies with the sucrose-carbon system. With sucrose, maximum restoration of adsorption capacity was achieved when a weight equivalent to 100% of the adsorbed sucrose was removed by thermal decomposition and steam gasification.

  10. Catalytic Conversion of Carbon-Containing Compounds into Valuable Chemicals and Fuels

    Science.gov (United States)

    Cheng, Zhuo

    Conversion of carbon-containing compounds, especially C1 compounds such as carbon dioxide and methane, to valuable chemicals and fuels will hopefully address concerns over decreasing supplies of fossil fuels and mitigate the eects of greenhouse gas emissions on global climate change. Many challenges, however, remain to be addressed before these technologies may be adopted on an industrial scale. Chiefly, catalysts must be developed to activate carbon-containing compounds from their thermodynamically stable ground states, using hydrogen, electrons, or heat as energy sources. We chose as model catalytic systems: 1) Metathesis of ethene and 2-butene; 2) Methane dehydrogenation and carbon dioxide hydrogenation. We developed three computational methodologies to study these processes across a range of length and time scales. First, we investigated how electronic structure affects the properties and reactivity of these catalyst systems; by computing the partial electronic density of states, electronic localization function, and excess spin density, we showed how redox supports, such as ceria, promote electron transfer reactions. We applied this to the studies of methane activation and carbon dioxide activation. Second, we developed a non-equilibrium thermodynamics approach to calculate energies of activation at nite temperatures, based on the Bronsted-Evans-Polanyi principle and the Nudged Elastic Band method. Third, we developed an approach to numerically compute heat capacities and other thermodynamic properties on extended catalytic systems that are comparable in accuracy and precision to methods that have been well-developed for gas-phase molecules. We applied these to the studies of metathesis propagation and carbon dioxide hydrogenation. We gained mechanistic, thermodynamic, and kinetic insight into the elementary steps that comprise larger reaction networks of interest to the broader catalysis community. Ultimately, these theoretical and computational predictions

  11. Hydrothermal synthesis of iron phosphate microspheres constructed by mesoporous polyhedral nanocrystals

    International Nuclear Information System (INIS)

    Novel monodispersed Fe5(PO4)4(OH)3·2H2O microspheres with the diameters of several micrometers were prepared by a facile one-step hydrothermal method without using any templates, only employing FeCl3·6H2O and NaNH4HPO4 as the initial materials. The obtained samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM), respectively. The characterizations revealed that the as-prepared microspheres are constructed by the polyhedral nanoparticles with an average diameter of 100 nm. The corresponding FePO4 microspheres assembled by mesoporous polyhedral nanocrystals can be easily obtained by calcining a sphere-like Fe5(PO4)4(OH)3·2H2O precursor. - Graphical abstract: Novel monodispersed Fe5(PO4)4(OH)3·H2O microspheres with a diameter of several micrometers were successfully obtained by a simple, template-free hydrothermal route. FePO4 microspheres constructed by mesoporous polyhedral FePO4 nanocrystals could be easily prepared by calcining an Fe5(PO4)4(OH)3·2H2O precursor. Display Omitted - Highlights: • Monodispersed Fe5(PO4)4(OH)3·2H2O microspheres were prepared by a facile hydrothermal method without using any templates • Fe5(PO4)4(OH)3·2H2O microspheres present a novel morphology, which was constructed by closely polyhedral nanoparticles. • The FePO4 microspheres assembled by mesoporous polyhedral nanocrystals obtained by calcining Fe5(PO4)4(OH)3·2H2O precursor

  12. Assessment of methods for organic and inorganic carbon quantification in carbonate-containing Mediterranean soils

    Science.gov (United States)

    Apesteguia, Marcos; Virto, Iñigo; Plante, Alain

    2014-05-01

    Quantification of soil organic matter (SOM) stocks and fluxes continues to be an important endeavor in assessments of soil quality, and more broadly in assessments of ecosystem functioning. The quantification of SOM in alkaline, carbonate-containing soils, such as those found in Mediterranean areas, is complicated by the need to differentiate between organic carbon (OC) and inorganic carbon (IC), which continues to present methodological challenges. Acidification is frequently used to eliminate carbonates prior to soil OC quantification, but when performed in the liquid phase, can promote the dissolution and loss of a portion of the OC. Acid fumigation (AF) is increasingly preferred for carbonate removal, but its effectiveness is difficult to assess using conventional elemental and isotopic analyses. In addition, the potential effects of AF on SOM are not well characterized. The objective of the current study was to apply a multi-method approach to determine the efficacy of carbonate removal by AF and its effects on the residual SOM. We selected a set of 24 surface agricultural soils representing a large range of textures, SOM contents and presumed carbonate contents. For each soil, OC was determined using wet combustion (Walkley-Black) and IC was determined using the calcimeter method. Samples were then subjected to elemental (total C) and isotopic (δ13C) analyses by dry combustion using a Costech autoanalyzer coupled to a Thermo Finnigan Delta Plus isotope ratio mass spectrometer (IRMS) before and after AF. IC was equated to total C determined after fumigation, and OC was estimated as the different in total C before and after AF. Samples were also subjected to ramped oxidation using a Netzsch STA109 PC Luxx thermal analyzer coupled to a LICOR 820A infrared gas analyzer (IRGA). Quantification of OC was performed using evolved gas analysis of CO2 (CO2-EGA) in the exothermic region 200-500° C associated with organic matter combustion. IC was quantified by CO2-EGA

  13. Chemical Hydrogen Storage Using Polyhedral Borane Anions and Aluminum-Ammonia-Borane Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, M. Frederick; Jalisatgi, Satish S.; Safronov, Alexander V.; Lee, Han Beak; Wu, Jianguo

    2010-10-01

    Phase 1. Hydrolysis of borohydride compounds offer the potential for significant hydrogen storage capacity, but most work to date has focused on one particular anion, BH4-, which requires high pH for stability. Other borohydride compounds, in particular polyhedral borane anions offer comparable hydrogen storage capacity without requiring high pH media and their long term thermal and hydrolytic stability coupled with non-toxic nature make them a very attractive alternative to NaBH4. The University of Missouri project provided the overall program focal point for the investigation of catalytic hydrolysis of polyhedral borane anions for hydrogen release. Due to their inherent stability, a transition metal catalyst was necessary for the hydrolysis of polyhedral borane anions. Transition metal ions such as cobalt, nickel, palladium and rhodium were investigated for their catalytic activity in the hydrolysis of nido-KB11H14, closo-K2B10H10, and closo-K2B12H12. The rate of hydrolysis follows first-order kinetics with respect to the concentration of the polyhedral borane anion and surface area of the rhodium catalyst. The rate of hydrolysis depends upon a) choice of polyhedral borane anion, c) concentration of polyhedral borane anion, d) surface area of the rhodium catalyst and e) temperature of the reaction. In all cases the yield of hydrogen was 100% which corresponds to ~7 wt% of hydrogen (based on material wt%). Phase 2. The phase 2 of program at the University of Missouri was focused upon developing aluminum ammonia-boranes (Al-AB) as chemical hydrogen storage materials, specifically their synthesis and studies of their dehydrogenation. The ammonia borane molecule (AB) is a demonstrated source of chemically stored hydrogen (19.6 wt%) which meets DOE performance parameters except for its regeneration from spent AB and elemental hydrogen. The presence of an aluminum center bonded to multiple AB residues might combine the efficiency of AB dehydrogenation with an aluminum

  14. Effect of photochemical self-action of carbon-containing aerosol: Wildfires

    Science.gov (United States)

    Konovalov, I. B.; Berezin, E. V.; Beekmann, M.

    2016-05-01

    It has been shown by numerical simulation that the rate of formation of secondary organic aerosols (SOAs) in smoke plumes caused by vegetation and peat fires under real conditions can significantly depend on the aerosol optical thickness (AOT). The AOT determines the photodissociation rate and hydroxyl radical concentration, which in turn determines the rate of SOA generation as a result of oxidation of semivolatile organic compounds. Quantitative analysis has been carried out for the situation that took place in European Russia during the 2010 Russian wildfires. The state-of-the-art 3D chemical transport model is used in this study; the simulations are optimized and validated using the data of monitoring of the particulate matter in the Moscow region and Finland. The findings indicate that it is important to allow for this effect in studies focused on the analysis and prediction of air pollution due to wildfires, as well as climate and weather studies, whose results may depend on the assumptions about the content and properties of atmospheric carbon-containing aerosol.

  15. Low-order harmonic generation in nanosecond laser ablation plasmas of carbon containing materials

    International Nuclear Information System (INIS)

    In this work we report on a systematic study of the spatiotemporal behaviour of low-order harmonics generated in nanosecond laser ablation plasmas of carbon containing materials. Plasmas were generated from targets of graphite and boron carbide ablated with a nanosecond Q-switched Nd:YAG laser at 1064 nm. Low-order harmonics (3rd and 5th) of the fundamental wavelength of a ns Nd:YAG driving laser, propagating perpendicularly to the ablation laser at variable time delays, were observed. The temporal study of the low-order harmonics generated under vacuum and atmospheres of Kr and Xe, revealed the presence of two populations that contribute to the harmonic generation (HG) at different times. It was found that under vacuum only small species contribute to the HG process, whereas under buffer gas, heavier species, such as clusters and nanoparticles, contribute to the HG at longer times. Optical emission spectroscopy, time of flight mass spectrometry and characterization of deposits collected on-line on a nearby substrate provided additional information that complemented the results of the spatiotemporal study of the generated harmonics. This approach to ablation plume analysis allows elucidating the identity of the nonlinear emitters in laser ablation plasmas and facilitates the investigation of efficient, nanoparticle-enhanced, coherent short wavelength generation processes.

  16. Three-Dimensional Porous Metal-Metalloporphyrin Framework Consisting of Nanoscopic Polyhedral Cages

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xi-Sen; Meng, Le; Cheng, Qigan; Kim, Chungsik; Wojtas, Lukasz; Chrzanowski, Matthew; Chen, Yu-Sheng; Zhang, X Peter; Ma, Shengqian [USF; (UC)

    2012-02-07

    An unprecedented nanoscopic polyhedral cage-containing metal-metalloporphyrin framework, MMPF-1, has been constructed from a custom-designed porphyrin ligand, 5,15-bis(3,5-dicarboxyphenyl)porphine, that links Cu2(carboxylate)4 moieties. A high density of 16 open copper sites confined within a nanoscopic polyhedral cage has been achieved, and the packing of the porphyrin cages via an 'ABAB' pattern affords MMPF-1 ultramicropores which render it selective toward adsorption of H2 and O2 over N2, and CO2 over CH4.

  17. Reactive bay functionalized perylene monoimide-polyhedral oligomeric silsesquioxane organic electronic dye

    Directory of Open Access Journals (Sweden)

    Wangatia Lodrick Makokha

    2015-03-01

    Full Text Available Aggregation-induced quenching is particularly detrimental in perylene diimides, which are characterized by a near-unity fluorescence quantum yield in solution but are far less emissive in the solid state. Previously, perylene diimide has been improved by linking it to the inorganic cage of polyhedral oligomeric silsesquioxanes. As a further study on perylene diimidepolyhedral oligomeric silsesquioxanes, we report on a double functionalized molecular structure, which can be used for substitution at the bay area and as a side group in other materials. Typical solution absorption and emission features of the perylene diimide fragment have been observed in this new reactive perylene diimide-polyhedral oligomeric silsesquioxane. Moreover, reduced stacking during aggregation and spherical particles exhibiting solid fluorescence have been obtained. Organic semiconducting material with enhanced solid state photophysical properties, like solid fluorescence is a subject of great interest owing to its possible high-tech applications in optoelectronic devices.

  18. Polyhedral construction of hollow ZnO microspheres by CO2 bubble templates

    International Nuclear Information System (INIS)

    A new type of complex ZnO hollow structures constructed by polyhedral particles has been prepared via a facile solution-phase route, in which ZnO precursors (ZnCO3) are synthesized through the reaction between Zn(CH3COOH)2 and NH4HCO3 in aqueous solution. Similar morphology of hollow ZnO microspheres can be effectively obtained simply by the pyrolysis method. The formation mechanism of hollow microspheres is mainly via an oriented aggregation process. CO2 bubble templates produced during the reaction to form the aggregation centers help the small particles to aggregate and form hollow microspheres. The surface morphology and size of these microspheres can be tuned by simply varying the reaction temperature. The hollow ZnO microspheres constructed by polyhedral particles may bring novel physical and chemical properties in the field of microscale electronics and photonics

  19. The set of realizations of a max-plus linear sequence is semi-polyhedral

    CERN Document Server

    Blondel, Vincent; Portier, Natacha

    2010-01-01

    We show that the set of realizations of a given dimension of a max-plus linear sequence is a finite union of polyhedral sets, which can be computed from any realization of the sequence. This yields an (expensive) algorithm to solve the max-plus minimal realization problem. These results are derived from general facts on rational expressions over idempotent commutative semirings: we show more generally that the set of values of the coefficients of a commutative rational expression in one letter that yield a given max-plus linear sequence is a semi-algebraic set in the max-plus sense. In particular, it is a finite union of polyhedral sets.

  20. Reactive bay functionalized perylene monoimide-polyhedral oligomeric silsesquioxane organic electronic dye

    OpenAIRE

    Wangatia Lodrick Makokha; Sun Bin; Zeng Ting; Zhu Meifang

    2015-01-01

    Aggregation-induced quenching is particularly detrimental in perylene diimides, which are characterized by a near-unity fluorescence quantum yield in solution but are far less emissive in the solid state. Previously, perylene diimide has been improved by linking it to the inorganic cage of polyhedral oligomeric silsesquioxanes. As a further study on perylene diimidepolyhedral oligomeric silsesquioxanes, we report on a double functionalized molecular structure, which can be used for substituti...

  1. Normally Admissible Stratifications and Calculation of Normal Cones to a Finite Union of Polyhedral Sets

    Czech Academy of Sciences Publication Activity Database

    Adam, Lukáš; Červinka, Michal; Pištěk, Miroslav

    -, - (2016). ISSN 1877-0533 R&D Projects: GA ČR GAP402/12/1309; GA ČR GA15-00735S Institutional support: RVO:67985556 Keywords : Union of polyhedral sets * Tangent cone * Frechet normal cone * Limiting normal cone * Normally admissible stratification * Time dependent problems * Delamination model Subject RIV: BA - General Mathematics Impact factor: 1.379, year: 2014 http://library.utia.cas.cz/separaty/2015/MTR/adam-0447818.pdf

  2. Approximate solution algorithm for multi-parametric non-convex programming problems with polyhedral constraints

    Directory of Open Access Journals (Sweden)

    Abay Molla Kassa

    2014-07-01

    Full Text Available In this paper, we developed a novel algorithmic approach for thesolution of multi-parametric non-convex programming problems withcontinuous decision variables. The basic idea of the proposedapproach is based on successive convex relaxation of each non-convexterms and sensitivity analysis theory. The proposed algorithm isimplemented using MATLAB software package and numericalexamples are presented to illustrate the effectiveness andapplicability of the proposed method on multi-parametric non-convexprogramming problems with polyhedral constraints.

  3. Adaptivity Support for MPSoCs Based on Process Migration in Polyhedral Process Networks

    OpenAIRE

    Emanuele Cannella; Onur Derin; Paolo Meloni; Giuseppe Tuveri; Todor Stefanov

    2012-01-01

    System adaptivity is becoming an important feature of modern embedded multiprocessor systems. To achieve the goal of system adaptivity when executing Polyhedral Process Networks (PPNs) on a generic tiled Network-on-Chip (NoC) MPSoC platform, we propose an approach to enable the run-time migration of processes among the available platform resources. In our approach, process migration is allowed by a middleware layer which comprises two main components. The first component concerns the inter-ti...

  4. Direct synthesis of hollow polyhedral ceria nano powders via a template-free mixed solvothermal route

    Institute of Scientific and Technical Information of China (English)

    刘俊亮; 颜雷鸣; 陈秀雷; 王绳芸; 张明; 田长安

    2015-01-01

    Novel mono-dispersed hollow polyhedral ceria nano powders with the average particle size of 250 nm were directly syn-thesized via a simple template-free mixed solvothermal method by using water-ethanol as the solvent. The formation of such hollow structure with the regular polyhedral particle shape was based on a solvent-controlled Ostwald ripening coupled self-templating proc-ess. The mixed solvent promoted the formation of the regular solid particles at the beginning of solvothermal reaction and drove the Ostwald ripening as the reaction went on. Owing to the Ostwald ripening and self-assembly of nano crystallites, ceria nano particles converted into the hollow structures with regular polyhedral shape during the solvothermal process just by increasing solvothermal reaction time. The as-synthesized hollow ceria nano powders exhibited strong absorptions in the UV-vis spectrum and the evaluated energy band gaps increased according to the shape evolution and size decrease of the nano particles, which demonstrated obvious blue shift effects.

  5. Polygonal Prism Mesh in the Viscous Layers for the Polyhedral Mesh Generator, PolyGen

    International Nuclear Information System (INIS)

    Polyhedral mesh has been known to have some benefits over the tetrahedral mesh. Efforts have been made to set up a polyhedral mesh generation system with open source programs SALOME and TetGen. The evaluation has shown that the polyhedral mesh generation system is promising. But it is necessary to extend the capability of the system to handle the viscous layers to be a generalized mesh generator. A brief review to the previous works on the mesh generation for the viscous layers will be made in section 2. Several challenging issues for the polygonal prism mesh generation will be discussed as well. The procedure to generate a polygonal prism mesh will be discussed in detail in section 3. Conclusion will be followed in section 4. A procedure to generate meshes in the viscous layers with PolyGen has been successfully designed. But more efforts have to be exercised to find the best way for the generating meshes for viscous layers. Using the extrusion direction of the STL data will the first of the trials in the near future

  6. "Self-assembly of uniform polyhedral silver nanocrystals into densest packings and exotic superlattices"

    Energy Technology Data Exchange (ETDEWEB)

    Henzie, Joel; Grunwald, Michael; Widmer-Cooper, Asaph; Geissler, Phillip L.; Yang, Peidong

    2011-03-01

    Understanding how polyhedra pack into extended arrangements is integral to the design and discovery of crystalline materials at all length scales. Much progress has been made in enumerating and characterizing the packing of polyhedral shapes, and the self-assembly of polyhedral nanocrystals into ordered superstructures. However, directing the self-assembly of polyhedral nanocrystals into densest packings requires precise control of particle shape, polydispersity,interactions and driving forces. Here we show with experiment and computer simulation that a range of nanoscale Ag polyhedra can self-assemble into their conjectured densest packings. When passivated with adsorbing polymer, the polyhedra behave as quasi-hard particles and assemble into millimetre-sized three-dimensional supercrystals by sedimentation.We also show, by inducing depletion attraction through excess polymer in solution, that octahedra form an exotic superstructure with complex helical motifs rather than the densest Minkowski lattice. Such large-scale Ag supercrystals may facilitate the design of scalable three-dimensional plasmonic metamaterials for sensing, nanophotonics, and photocatalysis.

  7. Molecular Structures of Free Boron Clusters

    Czech Academy of Sciences Publication Activity Database

    Hnyk, Drahomír; Wann, D. A.

    Cham: Springer International Publishing, 2015 - (Hnyk, D.; McKee, M.), s. 17-48. (Challenges and Advances in Computational Chemistry and Physics. 20). ISBN 978-3-319-22281-3 Institutional support: RVO:61388980 Keywords : AB-initio calculations * phase electron-diffraction * quantum-chemical calculations Subject RIV: CA - Inorganic Chemistry

  8. Solvothermal synthesis of hydrophobic chitin-polyhedral oligomeric silsesquioxane (POSS) nanocomposites.

    Science.gov (United States)

    Wysokowski, Marcin; Materna, Katarzyna; Walter, Juliane; Petrenko, Iaroslav; Stelling, Allison L; Bazhenov, Vasilii V; Klapiszewski, Łukasz; Szatkowski, Tomasz; Lewandowska, Olga; Stawski, Dawid; Molodtsov, Serguei L; Maciejewski, Hieronim; Ehrlich, Hermann; Jesionowski, Teofil

    2015-01-01

    Chitinous scaffolds isolated from the skeleton of marine sponge Aplysina cauliformis were used as a template for the deposition of polyhedral oligomeric silsesquioxanes (POSS). These chitin-POSS based composites with hydrophobic properties were prepared for the first time using solvothermal synthesis (pH 3, temp 80 °C), and were thoroughly characterized. The resulting material was studied using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and thermogravimetry. A mechanism for the chitin-POSS interaction after exposure to these solvothermal conditions is proposed and discussed. PMID:25889055

  9. A complementary electrochromic device based on polyaniline-tethered polyhedral oligomeric silsesquioxane and tungsten oxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Liying; Xiong, Shanxin; Ma, Jan; Lu, Xuehong [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2009-05-15

    In this paper we report a high-contrast complementary electrochromic device based on polyaniline-tethered polyhedral oligomeric silsesquioxane (POSS-PANI) and tungsten oxide (WO{sub 3}). The electrochromic properties, cyclic voltammetry behavior and coloration efficiency of the device are studied. Due to the loosely packed structure of POSS-PANI, it possesses more accessible doping sites and hence gives rise to a significantly higher electrochromic contrast than polyaniline (PANI). Furthermore, the replacement of PANI with POSS-PANI as the complementary layer for WO{sub 3} leads to an enhanced complementary effect, for which the underneath mechanism is also discussed. (author)

  10. Formation of polyhedral vesicles and polygonal membrane tubes induced by banana-shaped proteins

    Science.gov (United States)

    Noguchi, Hiroshi

    2015-12-01

    The shape transformations of fluid membranes induced by curved protein rods are studied using meshless membrane simulations. The rod assembly at low rod density induces a flat membrane tube and oblate vesicle. It is found that the polyhedral shapes are stabilized at high rod densities. The discrete shape transition between triangular and buckled discoidal tubes is obtained and their curvature energies are analyzed by a simple geometric model. For vesicles, triangular hosohedron and elliptic-disk shapes are formed in equilibrium, whereas tetrahedral and triangular prism shapes are obtained as metastable states.

  11. A piecewise linear finite element discretization of the diffusion equation for arbitrary polyhedral grids

    International Nuclear Information System (INIS)

    We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses piecewise linear weight and basis functions in the finite element approximation, and it can be applied on arbitrary polygonal (2-dimensional) or polyhedral (3-dimensional) grids. We show that this new PWL method gives solutions comparable to those from Palmer's finite-volume method. However, since the PWL method produces a symmetric positive definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids. (authors)

  12. A Piecewise Linear Finite Element Discretization of the Diffusion Equation for Arbitrary Polyhedral Grids

    International Nuclear Information System (INIS)

    We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses piecewise linear weight and basis functions in the finite element approximation, and it can be applied on arbitrary polygonal (2D) or polyhedral (3D) grids. We show that this new PWL method gives solutions comparable to those from Palmer's finite-volume method. However, since the PWL method produces a symmetric positive definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids

  13. The r-step Fibonacci-Hurwitz sequences in the binary polyhedral group

    Science.gov (United States)

    Deveci, Ömür; Ćiçekci, Deniz

    2016-04-01

    In [1], Deveci et al. defined the r-step Fibonacci-Hurwitz sequences from the Hurwitz matrices obtained from the characteristic polynomial of the k-step Fibonacci sequence. Also, they extended the r-step Fibonacci-Hurwitz sequences to groups. In this work, we obtain the periods of the r-step Fibonacci-Hurwitz sequences in the binary polyhedral group for generating triple {x, y, z} and generating pair {y, z} by the aid of the periods of the r-step Fibonacci-Hurwitz sequences according to modulo m.

  14. Asymmetrical Polyhedral Configuration of Giant Vesicles Induced by Orderly Array of Encapsulated Colloidal Particles

    Science.gov (United States)

    Natsume, Yuno; Toyota, Taro

    2016-01-01

    Giant vesicles (GVs) encapsulating colloidal particles by a specific volume fraction show a characteristic configuration under a hypertonic condition. Several flat faces were formed in GV membrane with orderly array of inner particles. GV shape changed from the spherical to the asymmetrical polyhedral configuration. This shape deformation was derived by entropic interaction between inner particles and GV membrane. Because a part of inner particles became to form an ordered phase in the region neighboring the GV membrane, free volume for the other part of particles increased. Giant vesicles encapsulating colloidal particles were useful for the model of “crowding effect” which is the entropic interaction in the cell. PMID:26752650

  15. Development of Numerical Method for Two-phase Flows on Three-dimensional Arbitrarily-shaped Polyhedral Meshes

    Science.gov (United States)

    Suzuki, Kohei; Omori, Takesi; Kajishima, Takeo

    2014-11-01

    Although the advantage of using arbitrarily-shaped polyhedral meshes for the industrial flow applications is clear, their employment to two-phase flows is rather limited due to the poor prediction accuracy of the existing numerical methods on such meshes. We present a numerical method based on VOF (Volume of Fluid) method which works on arbitrarily-shaped three-dimensional polyhedral meshes with little volume/shape error for the interface advection and with little curvature estimation error. To make the implementation in three-dimensional geometry feasible, we extend THINC (Tangent of Hyperbola Interface Capturing) method for polyhedral meshes which does not require laborious geometric arithmetics. In the oral presentation we will also show that the combination of RDF (Reconstructed Distance Function) algorithm and the carefully selected discretization procedure gives good performance in the interface curvature estimation.

  16. ComPASS : a tool for distributed parallel finite volume discretizations on general unstructured polyhedral meshes

    Directory of Open Access Journals (Sweden)

    Dalissier E.

    2013-12-01

    Full Text Available The objective of the ComPASS project is to develop a parallel multiphase Darcy flow simulator adapted to general unstructured polyhedral meshes (in a general sense with possibly non planar faces and to the parallelization of advanced finite volume discretizations with various choices of the degrees of freedom such as cell centres, vertices, or face centres. The main targeted applications are the simulation of CO2 geological storage, nuclear waste repository and reservoir simulations. The CEMRACS 2012 summer school devoted to high performance computing has been an ideal framework to start this collaborative project. This paper describes what has been achieved during the four weeks of the CEMRACS project which has been focusing on the implementation of basic features of the code such as the distributed unstructured polyhedral mesh, the synchronization of the degrees of freedom, and the connection to scientific libraries including the partitioner METIS, the visualization tool PARAVIEW, and the parallel linear solver library PETSc. The parallel efficiency of this first version of the ComPASS code has been validated on a toy parabolic problem using the Vertex Approximate Gradient finite volume spatial discretization with both cell and vertex degrees of freedom, combined with an Euler implicit time integration.

  17. Lipase-catalyzed Remote Kinetic Resolution of Quaternary Carbon-containing Alcohols and Determination of Their Absolute Configuration

    International Nuclear Information System (INIS)

    The quaternary carbon-containing alcohols (1-6) were resolved enantioselectively by various lipases such as PFL (Pseudomonas fluorescens lipase), LAK (Pseudomonas fluorescens lipase), CRL (Candida rugosa lipase) and PCL (Pseudomonas cepacia lipase). The enzymatic resolution of racemic alcohol (±)-2 gave the excellent enantioselectivity in favor of (S)-2d in 99% ee, while those of the racemic alcohols (1, 3, 4, 5 and 6) gave the resolved alcohols with moderate to good enantioselectivity. Also, their absolute configurations were determined by chemical transformation to the known compounds

  18. X-ray diffraction study of atomic structure features of amorphous carbon containing materials of nature and synthetic origin

    International Nuclear Information System (INIS)

    The atomic structure of amorphous carbon-containing materials such as carbon glass, spectroscopically pure carbon, schungite and anthracite is investigated using X ray diffraction analysis and computerized simulation. In computerized simulation of model gratings packing into packets an interlayer distance and a number of layer in a packet varied and a gratings turn is predetermined randomly. The quantity of gratings in a packet is shown to vary between four for anthracite and six for spectroscopically pure coal. The interlayer distance for all amorphous carbonaceous materials is above 3.35 A which is typical for graphite

  19. Spontaneous growth of the polyhedral fullerene crystals in the supersaturated Ni-C(60) composite

    Czech Academy of Sciences Publication Activity Database

    Vacík, Jiří; Lavrentiev, Vasyl; Michalcová, A.; Abe, H.; Horák, Pavel

    2011-01-01

    Roč. 509, č. 1 (2011), S380-S383. ISSN 0925-8388. [17th International Symposium on Metastable, Amorphous and Nanostructured Materials (ISMANAM 2010). Zurich, 04.09.2010-09.06.2010] R&D Projects: GA ČR GAP107/11/1856; GA AV ČR(CZ) KAN400480701; GA AV ČR(CZ) IAA400320901; GA AV ČR IAA200480702; GA ČR GA106/09/1264; GA MŠk(CZ) LC06041 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z40320502 Keywords : Nickel * Fullerenes * Phase separation * Polyhedral particles Subject RIV: JJ - Other Materials Impact factor: 2.289, year: 2011

  20. Surface modification and reinforcement of silica aerogels using polyhedral oligomeric silsesquioxanes.

    Science.gov (United States)

    Duan, Yannan; Jana, Sadhan C; Reinsel, Anna M; Lama, Bimala; Espe, Matthew P

    2012-10-30

    This study evaluated polyhedral oligomeric silsesquioxane (POSS) molecules as useful, multifunctional reinforcing agents of silica aerogels. Silica aerogels have low-density and high surface area, although their durability is often compromised by the inherent fragility and strong moisture absorption behavior of the silica networks. POSS molecules carrying phenyl, iso-butyl, and cyclohexyl organic side groups, and several Si-OH functionalities were incorporated into silica networks via reactions between Si-OH functionalities in POSS molecules and silanes. Solid state (13)C and (29)Si NMR spectra established that greater than 90% of POSS molecules grafted onto silica networks and led to an increase in fractal dimensions. An almost 6-fold increase in compressive modulus was achieved with less than 5 wt % trisilanol phenyl POSS, and a 50-fold decrease in polarity with negligible changes in density were seen in aerogels modified with less than 5 wt % trisilanol isobutyl POSS. PMID:23046155

  1. Polybenzimidazole and sulfonated polyhedral oligosilsesquioxane composite membranes for high temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Aili, David; Allward, Todd; Alfaro, Silvia Martinez;

    2014-01-01

    Composite membranes based on poly(2,2′(m-phenylene)-5,5́bibenzimidazole) (PBI) and sulfonated polyhedral oligosilsesquioxane (S-POSS) with S-POSS contents of 5 and 10wt.% were prepared by solution casting as base materials for high temperature polymer electrolyte membrane fuel cells. With membranes...... based on pure PBI as a reference point, the composite membranes were characterized with respect to spectroscopic and physicochemical properties. After doping with phosphoric acid, the composite membranes showed considerably improved ex situ proton conductivity under anhydrous as well as under fully...... humidified conditions in the 120-180°C temperature range. The conductivity improvements were also confirmed by in situ fuel cell tests at 160°C and further supported by the electrochemical impedance spectroscopy data based on the operating membrane electrode assemblies, demonstrating the technical...

  2. Synthesis of PtCo3 polyhedral nanoparticles and evolution to Pt3Co nanoframes

    Science.gov (United States)

    Becknell, Nigel; Zheng, Cindy; Chen, Chen; Yu, Yi; Yang, Peidong

    2016-06-01

    Bimetallic nanoframes have great potential for achieving new levels of catalytic activity in various heterogeneous reactions due to their high surface area dispersion of expensive noble metals on the exterior and interior surfaces of the structure. PtCo3 nanoparticles with polyhedral shapes were synthesized by a hot-injection method. Scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy (EDS) showed that these nanoparticles demonstrated elemental segregation of platinum to the edges of the polyhedron, forming the basis for a framework nanostructure. The process of preferential oxidative leaching which removed cobalt from the interior of the framework was tracked by EDS and inductively coupled plasma optical emission spectroscopy. This evolution procedure left the platinum-rich edges intact to form a Pt3Co nanoframe. This is the first reported synthesis of a platinum-cobalt nanoframe and could have potential applications in catalytic reactions such as oxygen reduction.

  3. A Piecewise Linear Finite Element Discretization of the Diffusion Equation for Arbitrary Polyhedral Grids

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, T S; Adams, M L; Yang, B; Zika, M R

    2005-07-15

    We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses piecewise linear weight and basis functions in the finite element approximation, and it can be applied on arbitrary polygonal (2D) or polyhedral (3D) grids. We show that this new PWL method gives solutions comparable to those from Palmer's finite-volume method. However, since the PWL method produces a symmetric positive definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids.

  4. A piecewise linear finite element discretization of the diffusion equation for arbitrary polyhedral grids

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, T.S.; Adams, M.L. [Texas A M Univ., Dept. of Nuclear Engineering, College Station, TX (United States); Yang, B.; Zika, M.R. [Lawrence Livermore National Lab., Livermore, CA (United States)

    2005-07-01

    We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses piecewise linear weight and basis functions in the finite element approximation, and it can be applied on arbitrary polygonal (2-dimensional) or polyhedral (3-dimensional) grids. We show that this new PWL method gives solutions comparable to those from Palmer's finite-volume method. However, since the PWL method produces a symmetric positive definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids. (authors)

  5. Synthesis and comparative toxicology of a series of polyhedral borane anion-substituted tetraphenyl porphyrins.

    Science.gov (United States)

    Koo, Myoung-Seo; Ozawa, Tomoko; Santos, Raquel A; Lamborn, Kathleen R; Bollen, Andrew W; Deen, Dennis F; Kahl, Stephen B

    2007-02-22

    Three structurally similar tetraphenylporphyrins bearing polyhedral borane anions have been synthesized and their toxicological profiles obtained in rats. These conjugates were found to have quite different acute toxicities as manifested at the maximum tolerated dose (MTD). When given at the MTD and observed over 28 days, the most acutely toxic porphyrin was found to be devoid of toxicity, as measured by blood chemistry panels. The remaining two less acutely toxic compounds both elicited significant changes, characterized by moderate to severe thrombocytopenia, failure to gain weight normally and changes in liver enzymes indicative of mild hepatotoxicity. All toxic effects were transient, with platelets rebounding to above normal levels at day 28. We conclude that thrombocytopenia is the dose limiting toxicity for boronated porphyrins in mammals and suggest that these effects may be due to the porphyrin, not the borane or carborane. PMID:17253677

  6. A piecewise linear finite element discretization of the diffusion equation for arbitrary polyhedral grids

    International Nuclear Information System (INIS)

    We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses recently introduced piecewise linear weight and basis functions in the finite element approximation and it can be applied on arbitrary polygonal (2D) or polyhedral (3D) grids. We first demonstrate some analytical properties of the PWL method and perform a simple mode analysis to compare the PWL method with Palmer's vertex-centered finite-volume method and with a bilinear continuous finite element method. We then show that this new PWL method gives solutions comparable to those from Palmer's. However, since the PWL method produces a symmetric positive-definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids

  7. Synthesis and Luminescent Property of Polycarbazole/Polyhedral Oligomeric Silsesquioxane Nanocomposites

    Institute of Scientific and Technical Information of China (English)

    ZHU Yu-fang; ZHAO Jun-feng; WANG Xi; LI Qi-fang

    2008-01-01

    Polyvinylcarbazole(PVK) composites containing organic-inorganic hybrid polyhedral oligomeric silsesquioxane(POSS) PVK-POSS were prepared by free radical polymerization.POSS monomers reacted with vinylcarbazole and were completely dispersed at molecular level in PVK matrix and PVK-POSS nanocomposites display higher glass transition temperature(Tg) in comparison with neat PVK.Optical properties of PVK/POSS nanocomposites were investigated by UV-spectrum and PL-spectrum and the results show that the PVK-POSS nanoparticles have a good interface effect and improve color purity effectively.The maximum absorption wavelength bathochromically shifts gradually with the increasing of the content of POSS.The luminescent intensity becomes higher and higher with the increase of POSS content,and reaches its maximum luminescent intensity when the POSS content is 3% (mass fraction),while some POSS-rich nanoparticles are present in matrix when contents of POSS are beyond 5%.

  8. Efficient light-emitting devices based on platinum-complexes-anchored polyhedral oligomeric silsesquioxane materials

    KAUST Repository

    Yang, Xiaohui

    2010-08-24

    The synthesis, photophysical, and electrochemical characterization of macromolecules, consisting of an emissive platinum complex and carbazole moieties covalently attached to a polyhedral oligomeric silsesquioxane (POSS) core, is reported. Organic light-emitting devices based on these POSS materials exhibit a peak external quantum efficiency of ca. 8%, which is significantly higher than that of the analogous devices with a physical blend of the platinum complexes and a polymer matrix, and they represent noticeable improvement in the device efficiency of solution-processable phosphorescent excimer devices. Furthermore, the ratio of monomer and excimer/aggregate electroluminescent emission intensity, as well as the device efficiency, increases as the platinum complex moiety presence on the POSS macromolecules decreases. © 2010 American Chemical Society.

  9. Polybenzimidazole and sulfonated polyhedral oligosilsesquioxane composite membranes for high temperature polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Composite membranes based on poly(2,2′(m-phenylene)-5,5′bibenzimidazole) (PBI) and sulfonated polyhedral oligosilsesquioxane (S-POSS) with S-POSS contents of 5 and 10 wt.% were prepared by solution casting as base materials for high temperature polymer electrolyte membrane fuel cells. With membranes based on pure PBI as a reference point, the composite membranes were characterized with respect to spectroscopic and physicochemical properties. After doping with phosphoric acid, the composite membranes showed considerably improved ex situ proton conductivity under anhydrous as well as under fully humidified conditions in the 120-180 °C temperature range. The conductivity improvements were also confirmed by in situ fuel cell tests at 160 °C and further supported by the electrochemical impedance spectroscopy data based on the operating membrane electrode assemblies, demonstrating the technical feasibility of the novel electrolyte materials

  10. Self-assembly of three-legged patchy particles into polyhedral cages

    International Nuclear Information System (INIS)

    The self-assembly of rigid three-legged building blocks into polyhedral cages is investigated by patchy particle simulations. A four-site anisotropic interaction potential is introduced to make pairs of overlapping legs bind in an anti-parallel fashion, thereby forming the edges of a polyhedron of pentagons and hexagons. A torsional potential, reflecting an asymmetry or polarity in the legs' binding potential, proves crucial for the successful formation of closed fullerene-like cages. Self-assembly proceeds by a nucleation-and-growth mechanism, with a high success rate of cage closure. The size distribution of the self-assembled buckyballs is largely determined by the pucker angle of the particle. Nature explores a similar building block, the clathrin triskelion, to regulate vesicle formation at the cell membrane during endocytosis.

  11. Compatible discrete operator schemes on polyhedral meshes for elliptic and Stokes equations

    International Nuclear Information System (INIS)

    This thesis presents a new class of spatial discretization schemes on polyhedral meshes, called Compatible Discrete Operator (CDO) schemes and their application to elliptic and Stokes equations In CDO schemes, preserving the structural properties of the continuous equations is the leading principle to design the discrete operators. De Rham maps define the degrees of freedom according to the physical nature of fields to discretize. CDO schemes operate a clear separation between topological relations (balance equations) and constitutive relations (closure laws). Topological relations are related to discrete differential operators, and constitutive relations to discrete Hodge operators. A feature of CDO schemes is the explicit use of a second mesh, called dual mesh, to build the discrete Hodge operator. Two families of CDO schemes are considered: vertex-based schemes where the potential is located at (primal) mesh vertices, and cell-based schemes where the potential is located at dual mesh vertices (dual vertices being in one-to-one correspondence with primal cells). The CDO schemes related to these two families are presented and their convergence is analyzed. A first analysis hinges on an algebraic definition of the discrete Hodge operator and allows one to identify three key properties: symmetry, stability, and P0-consistency. A second analysis hinges on a definition of the discrete Hodge operator using reconstruction operators, and the requirements on these reconstruction operators are identified. In addition, CDO schemes provide a unified vision on a broad class of schemes proposed in the literature (finite element, finite element, mimetic schemes... ). Finally, the reliability and the efficiency of CDO schemes are assessed on various test cases and several polyhedral meshes. (author)

  12. Highly stable linear carbonate-containing electrolytes with fluoroethylene carbonate for high-performance cathodes in sodium-ion batteries

    Science.gov (United States)

    Lee, Yongwon; Lee, Jaegi; Kim, Hyungsub; Kang, Kisuk; Choi, Nam-Soon

    2016-07-01

    Employing linear carbonates such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as electrolyte solvents provides an opportunity to design appropriate electrolyte systems for high-performance sodium-ion batteries (SIBs). However, in practice, the use of linear carbonate-containing electrolytes is quite challenging because linear carbonates readily decompose at Na metal electrodes or sodiated anodes. One of the promising approaches is using an electrolyte additive to resolve the critical problems related to linear carbonates. Our investigation reveals that remarkable enhancement in electrochemical performance of Na4Fe3(PO4)2(P2O7) cathodes with linear carbonate-containing electrolytes is achieved by using a fluoroethylene carbonate (FEC) additive. Importantly, the initial Coulombic efficiency of the Na deposition/stripping on a stainless steel (SS) electrode is drastically improved from 16% to 90% by introducing the FEC additive into ethylene carbonate (EC)/propylene carbonate (PC)/DEC (5/3/2, v/v/v)/0.5 M NaClO4. The underlying mechanism of FEC at the electrode-electrolyte interface is clearly demonstrated by 13C nuclear magnetic resonance (NMR). In addition, the Na4Fe3(PO4)2(P2O7) cathode in EC/PC/DEC (5/3/2, v/v/v)/0.5 M sodium perchlorate (NaClO4) with FEC delivers a discharge capacity of 90.5 mAh g-1 at a current rate of C/2 and exhibits excellent capacity retention of 97.5% with high Coulombic efficiency of 99.6% after 300 cycles at 30 °C.

  13. Matrix solution for Polyhedration of Na-K-Ca-Cl-N-O, Na-K-Mo-W-F-O and Na-Ba-B-F-O Systems

    International Nuclear Information System (INIS)

    Methods of matrix solution for tasks of multicomponent systems polyhedration, connections between mass-centric coordinates of systems and their subsystems determination, belonging of a point to concentration simplex definition are proposed.

  14. Tracking Control in Billiards Using Mirrors without Smoke, Part I: Lyapunov-Based Local Tracking in Polyhedral Regions

    OpenAIRE

    Forni, Fulvio; Teel, Andrew; Zaccarian, Luca

    2011-01-01

    In this paper we formulate the tracking problem of a translating mass in a polyhedral billiard as a stabilization problem for a suitable set. Due to the discontinuous dynamics arising from nonsmooth impacts, the tracking problem is formulated within a hybrid systems framework and a Lyapunov function is given, which decreases during flow (continuous motion) and remains constant across jumps (impacts of the masses). To guarantee non-increase of the Lyapunov function at jumps, we introduce a nov...

  15. Construction of porous cationic frameworks by crosslinking polyhedral oligomeric silsesquioxane units with N-heterocyclic linkers

    Science.gov (United States)

    Chen, Guojian; Zhou, Yu; Wang, Xiaochen; Li, Jing; Xue, Shuang; Liu, Yangqing; Wang, Qian; Wang, Jun

    2015-06-01

    In fields of materials science and chemistry, ionic-type porous materials attract increasing attention due to significant ion-exchanging capacity for accessing diversified applications. Facing the fact that porous cationic materials with robust and stable frameworks are very rare, novel tactics that can create new type members are highly desired. Here we report the first family of polyhedral oligomeric silsesquioxane (POSS) based porous cationic frameworks (PCIF-n) with enriched poly(ionic liquid)-like cationic structures, tunable mesoporosities, high surface areas (up to 1,025 m2 g-1) and large pore volumes (up to 0.90 cm3 g-1). Our strategy is designing the new rigid POSS unit of octakis(chloromethyl)silsesquioxane and reacting it with the rigid N-heterocyclic cross-linkers (typically 4,4‧-bipyridine) for preparing the desired porous cationic frameworks. The PCIF-n materials possess large surface area, hydrophobic and special anion-exchanging property, and thus are used as the supports for loading guest species PMo10V2O405- the resultant hybrid behaves as an efficient heterogeneous catalyst for aerobic oxidation of benzene and H2O2-mediated oxidation of cyclohexane.

  16. Polyhedral Oligomeric Silsesquioxane-Containing Thiol-ene Fibers with Tunable Thermal and Mechanical Properties.

    Science.gov (United States)

    Fang, Yichen; Ha, Heonjoo; Shanmuganathan, Kadhiravan; Ellison, Christopher J

    2016-05-01

    Polyhedral oligomeric silsesquioxanes (POSS) are versatile inorganic-organic hybrid building blocks that have potential applications as reinforcement nanofillers, thermal stabilizers, and catalyst supports for metal nanoparticles. However, fabrication of fibrous materials with high POSS content has been a challenge because of the aggregation and solubility limits of POSS units. In this paper, we describe a robust and environmentally friendly fabrication approach of inorganic-organic hybrid POSS fibers by integrating UV initiated thiol-ene polymerization and centrifugal fiber spinning. The use of monomeric liquids in this approach not only reduces the consumption of heat energy and solvent, but it also promotes homogeneous mixing of organic and inorganic components that allows integration of large amount of POSS (up to 80 wt %) into the polymer network. The POSS containing thiol-ene fibers exhibited enhanced thermomechanical properties compared to purely organic analogs as revealed by substantial increases in residual weight and a factor of 4 increase in modulus after thermal treatment at 1000 °C. This simple fabrication approach combined with the tunability in fiber properties afforded by tailoring monomer composition make POSS containing thiol-ene fibers attractive candidates for catalyst supports and filtration media, particularly in high-temperature and harsh environments. PMID:27057758

  17. Liquid crystal alignment by polyhedral oligomeric silsesquioxane (POSS)-polyimide nanocomposites

    Science.gov (United States)

    Liu, Han-Shiang; Jeng, Shie-Chang

    2013-05-01

    Polyimide (PI) films are widely used in the liquid crystal display (LCD) industry to align liquid crystal (LC) molecules in a specific orientation with a pretilt angle θp on the PI alignment films. It was observed that physical dispersion of polyhedral oligomeric silsesquioxane (POSS) nanoparticles in commercial homogenous PIs decreases the surface energy of the PI alignment films and generates a controllable θp in the range 0° < θp < 90°, which is not easily achieved by complicate PI synthesis. Characteristics of POSS-PI nanocomposites were studied to investigate the influence of POSS nanoparticles on PIs. Increased absorption in the infrared spectra and decreased decomposition temperature and glass transition temperature with POSS doped concentration in PI were observed due to the increase in free volume of POSS-PI nanocomposites. Such nanoscale hybridization suggests a novel approach to tune the properties of PIs through modification of molecular interaction. A fast response no-bias optically-compensated bend (OCB) LCD with a pretilt angle of 68° was also demonstrated in this work.

  18. Structure-properties relationships of polyhedral oligomeric silsesquioxane (POSS filled PS nanocomposites

    Directory of Open Access Journals (Sweden)

    J. J. Schwab

    2012-07-01

    Full Text Available The polyhedral oligomeric silsesquioxane (POSS additivated polystyrene (PS based nanocomposites were prepared by melt processing and the structure-properties relationships of the POSS-PS systems were compared to those of the neat PS. In order to investigate the effect of these structural parameters on the final properties of the polymer nanocomposites, five different kinds of POSS samples were used, in particular, POSS with different inorganic cage and with different organic pendent groups. The rheological investigation suggests clearly that the POSS acts as a plasticizer and that the processability of the PS was positively modified. The affinity between the POSS samples and the PS matrix was estimated by the calculated theoretical solubility parameters, considering the Hoy’s method and by morphology analysis. Minor difference between the solubility parameter of POSS and the matrix means better compatibility and no aggregation tendency. Furthermore, the POSS loading leads to a decrease of the rigidity, of the glass transition temperature and of the damping factor of the nanocomposite systems. The loading of different POSS molecules with open cage leads to a more pronounced effect on all the investigated properties that the loading of the POSS molecules with closed cage. Moreover, the melt properties are significantly influenced by the type of inorganic framework, by the type of the pendent organic groups and by the interaction between the POSS organic groups and the host matrix, while, the solid state properties appears to be influenced more by the kind of cage.

  19. Dielectric properties of polyhedral oligomeric silsesquioxane (POSS)-based nanocomposites at 77k

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Ming-Jen; Gorzkowski, Edward; McAllister, Kelly, E-mail: pan@anvil.nrl.navy.mi [Multifunctional Materials Branch, Code 6350 U.S. Naval Research Laboratory 4555 Overlook Avenue SW, Washington, DC 20375 (United States)

    2011-10-29

    The goal of this study is to develop dielectric nanocomposites for high energy density applications at liquid nitrogen temperature by utilizing a unique nano-material polyhedral oligomeric silsesquioxanes (POSS). A POSS molecule is consisted of a silica cage core with 8 silicon and 12 oxygen atoms and organic functional groups attached to the corners of the cage. In this study, we utilize POSS for the fabrication of nanocomposites both as a silica nanoparticle filler to enhance the breakdown strength and as a surfactant for effective dispersion of high permittivity ceramic nanoparticles in a polymer matrix. The matrix materials selected for the study are polyvinylidene fluoride (PVDF) and poly(methyl methacrylate) (PMMA). The ceramic nanoparticles are barium strontium titanate (BST 50/50) and strontium titanate. The dielectric properties of the solution-cast nanocomposites films were correlated to the composition and processing conditions. We determined that the addition of POSS did not provide enhanced dielectric performance in PVDF- and PMMA-based materials at either room temperature or 77K. In addition, we found that the dielectric breakdown strength of PMMA is lower at 77K than at room temperature, contradicting literature data.

  20. Quantifying the thermodynamic interactions of polyhedral boranes in solution to guide nanocomposite fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Mutz, M. [University of Tennessee, Department of Chemistry (United States); Eastwood, Eric [Honeywell Kansas City Plant (United States); Lee, Mark E. [University of Missouri (United States); Bowen, Daniel E. [Honeywell Kansas City Plant (United States); Dadmun, M. D., E-mail: dad@utk.edu [University of Tennessee, Department of Chemistry (United States)

    2012-11-15

    The solubility of boron containing nanoparticles in a variety of solvents is quantified using static light scattering in conjunction with refractometry. Four polyhedral boranes were tested in this work, using refractometry to obtain dn/dc, while static light scattering quantifies A{sub 2}. A{sub 2} obtained from these measurements was then used to calculate {chi}, the solute-solvent interaction parameter, and the Hildebrand solubility parameter, {delta}, which provides a quantifiable method to identify good solvents. Of the nanoparticles studied, 1,3-di-o-carboranylpropane is thermodynamically stable in toluene, with a {chi} less than 0.5, a solubility limit of 2.47 mg/mL, and all solutions remaining clear with no visible particle settling. For all of the particles tested, there was good correlation between the physical observations of the solutions, {chi}, and {delta}. For instance, lower values of {chi} correspond to a smaller radius of gyration (R{sub g}). A list of suitable solvents based on {delta} is also presented.

  1. Quantifying the thermodynamic interactions of polyhedral boranes in solution to guide nanocomposite fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Mutz, M [The University of Tennessee; Eastwood, Eric Allen [ORNL; LeeJr, Mark E [University of Missouri; BowenIII, Daniel E [Honeywell, Inc.; Dadmun, Mark D [ORNL

    2012-01-01

    The solubility of boron containing nanoparticles in a variety of solvents is quantified using static light scattering in conjunction with refractometry. Four polyhedral boranes were tested in this work, using refractometry to obtain dn/dc, while static light scattering quantifies A2. A2 obtained from these measurements was then used to calculate v, the solute solvent interaction parameter, and the ildebrand solubility parameter, d, which provides a quantifiable method to identify good solvents. Of the nanoparticles studied, 1,3-di-o-carboranylpropane is thermodynamically stable in toluene, with a v less than 0.5, a solubility limit of 2.47 mg/mL, and all solutions remaining clear with no visible particle settling. For all of the particles tested, there was good correlation between the physical observations of the solutions, v, and d. For instance, lower values of v correspond to a smaller radius of gyration (Rg). A list of suitable solvents based on d is also presented.

  2. Synthesis and properties of hydroxyl-terminated polybutadiene-based polyurethanes reinforced with polyhedral oligomeric silsesquioxanes.

    Science.gov (United States)

    Kim, Ho-Joong; Kwon, Younghwan; Kim, Chang Kee

    2014-11-01

    Polyurethane/polyhedral oligomeric silsesquioxane (PU/POSS) hybrid composites are prepared by a one-step PU reaction using hydroxyl-terminated polybutadiene (HTPB) prepolymer, isophorone diisocyanate (IPDI) and either non-reactive or reactive POSS molecule. The effect of incorporation of functionalized POSS molecules covalently bonded or physically blended into PU matrix is investigated in terms of mechanical reinforcement and thermal stability of these resulting PU/POSS hybrid composites. PU/POSS hybrid composites prepared with reactive POSS molecules exhibit the mechanical reinforcement while maintaining low glass transition temperataure (T(g)), probably due to the fact that reactive POSS molecules chemically incorporated in PU are aggregated to crystallize, effectively working as a physical crosslinking in PU/POSS hybrid composites. This can be advantageous in that mechanical reinforcement of PU/POSS hybrid composites can be achived without sacrificing the low temperature properties of these composites. However, the contribution of POSS molecules incorporated covalently into PU matrix is virtually absent on the thermal decomposition temperature (T(d,max)) measured using TGA/DTG. Thermal degradation behavior of these hybrid composites in the early stage rather appears to depend preferably on characteristics of POSS molecules incorporated. PMID:25958582

  3. Self-assembled amphiphilic polyhedral oligosilsesquioxane (POSS) grafted poly(vinyl alcohol) (PVA) nanoparticles

    International Nuclear Information System (INIS)

    In the present study, spherical nanoparticles (NPs) containing polyhedral oligosilsesquioxane (POSS) as an inner hydrophobic core and poly(vinyl alcohol) PVA as a hydrophilic outer shell were prepared by dialysis approach. Preparation of amphiphilic POSS-grafted-PVA co-polymer was characterized by 1H NMR and FT-IR. The results indicated urethane linkage between monoisocyanate group of POSS macromer and the hydroxyl groups of PVA. The dynamic light scattering (DLS) and electrophoretic light scattering (ELS) of the NPs revealed that they have an average hydrodynamic diameter and negative zeta (ζ)-potential of 215 nm and - 161 mV, respectively. Atomic force microscopy (AFM) and bio-transmission electron microscope (BIO-TEM) have shown unagglomerated NPs within a diameter range of 60-90 nm. The prepared NPs were investigated to improve the control release of anticancer drug; paclitaxel as a model drug. Due to drug loading, the hydrodynamic diameter and negative zeta (ζ)-potential have changed to 325 nm and - 14 mV, respectively. In addition, in-vitro drug release experiments were conducted; the obtained results explicated continuous release for over 40 days. However, in case of using pure drug only, the drug completely released within 1 h.

  4. Transparent cellulose/polyhedral oligomeric silsesquioxane nanocomposites with enhanced UV-shielding properties.

    Science.gov (United States)

    Feng, Ye; Zhang, Jinming; He, Jiasong; Zhang, Jun

    2016-08-20

    The solubility of eight types of polyhedral oligomeric silsesquioxane (POSS) derivatives in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) and the dispersion of POSS in cellulose matrix were examined. Only a special POSS containing both aminophenyl and nitrophenyl groups (POSS-AN, NH2:NO2=2:6) was selected to prepare nanocomposites, because of its good solubility in AmimCl and high stability during the preparation process. POSS-AN nanoparticles were uniformly dispersed in a cellulose matrix with a size of 30-40nm, and so the resultant cellulose/POSS-AN nanocomposite films were transparent. The mechanical properties of the films achieved a maximum tensile strength of 190MPa after addition of 2wt% POSS-AN. Interestingly, all of the cellulose/POSS-AN films exhibited high UV-absorbing capability. For the 15wt% cellulose/POSS-AN film, the transmittance of UVA (315-400nm) and UVB (280-315nm) was only 9.1% and nearly 0, respectively. The UV aging and shielding experiments showed that the transparent cellulose/POSS-AN nanocomposite films possessed anti-UV aging and UV shielding properties. PMID:27178922

  5. Hydrothermal synthesis of microscaled Cu@C polyhedral composites and their sensitivity to convergent electron beams.

    Science.gov (United States)

    Hao, Qin; Xu, Liqiang; Li, Guangda; Qian, Yitai

    2009-06-01

    Copper microparticles (2-5 um) encapsulated in carbonaceous shell polyhedral composites were mildly prepared via a one-pot hydrothermal process using copper nitrate, glucose, and sodium citrate at 150 degrees C, in which the glucose was found to play reducer and graphite source roles during the formation of these core-shell-like composites. Thermal stability results indicated that their weights remain almost unchanged below 240 degrees C in ambient atmosphere. It is interesting that the copper microparticles could be partially released out and translated into monodisperse Cu nanoparticles around the initial composites under the convergent electron beams in a transmission electron microscope (TEM). This phenomenon is an appealing discovery, which might endow the Cu@C composite with new functions; for example, it might be applied as a sensitive detector for the leakage of electron beams or other substances for the sake of being a safeguard. In addition, the corresponding hollow carbonaceous polyhedra were also obtained after the acid treatment, which might be used as a template to fabricate other kinds of polyhedra. PMID:19466787

  6. Experimental and theoretical study of the heating dynamics of carbon-containing optothermal fibre converters for laser surgery

    Science.gov (United States)

    Belikov, A. V.; Skrypnik, A. V.; Kurnyshev, V. Yu; Shatilova, K. V.

    2016-06-01

    We have studied carbon-containing optothermal fibre converters (COTFCs) that are located on the distal end of a quartz – quartz optical fibre for delivering laser radiation in medical laser surgery systems and differ in the thickness and structure of the layer of a material converting laser radiation into heat. The heating dynamics of 'thin-film' and '3D' converters have been investigated at average incident 980-nm semiconductor laser beam powers of 0.3, 1.0 and 4.0 W, with the converters placed freely in air. The results demonstrate that, before the instant of disintegration, the efficiency of laser heating of the converter surface can reach 3000 °C W-1 for thin-film converters, 1000 °C W-1 for spherical 3D converters and 55 °C W-1 for planar 3D converters. The thin-film converter breaks down at an average laser beam power as low as 0.30 +/- 0.05 W, which is accompanied by a considerable reduction in heating efficiency and is caused by the disintegration of the carbon film on its surface. The spherical 3D converter breaks down at an average power of 4.0 +/- 0.1 W, as a result of the disintegration of the carbon film on its surface and partial melting of a modified layer containing microbubbles. The carbon film on the surface of the planar 3D converter also disintegrates at an average power of 4.0 +/- 0.1 W, but the structure of the modified layer remains unchanged. We have constructed structural and optophysical models of the converters by simulating light absorption in carbon films on the surface of the COTFC and inside the microbubbles present in the modified layer of the converters. The proposed models of the COTFCs have been shown to adequately describe real converters.

  7. Marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS

    Directory of Open Access Journals (Sweden)

    Luciano Ribeiro CORREA NETTO

    2015-10-01

    Full Text Available Marginal integrity is one of the most crucial aspects involved in the clinical longevity of resin composite restorations.Objective To analyze the marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS.Material and Methods A base composite (B was produced with an organic matrix with UDMA/TEGDMA and 70 wt.% of barium borosilicate glass particles. To produce the model composite, 25 wt.% of UDMA were replaced by POSS (P25. The composites P90 and TPH3 (TP3 were used as positive and negative controls, respectively. Marginal integrity (%MI was analyzed in bonded class I cavities. The volumetric polymerization shrinkage (%VS and the polymerization shrinkage stress (Pss - MPa were also evaluated.Results The values for %MI were as follows: P90 (100% = TP3 (98.3% = B (96.9% > P25 (93.2%, (p<0.05. The %VS ranged from 1.4% (P90 to 4.9% (P25, while Pss ranged from 2.3 MPa (P90 to 3.9 MPa (B. For both properties, the composite P25 presented the worst results (4.9% and 3.6 MPa. Linear regression analysis showed a strong positive correlation between %VS and Pss (r=0.97, whereas the correlation between Pss and %MI was found to be moderate (r=0.76.Conclusions The addition of 25 wt.% of POSS in methacrylate organic matrix did not improve the marginal integrity of class I restorations. Filtek P90 showed lower polymerization shrinkage and shrinkage stress when compared to the experimental and commercial methacrylate composite.

  8. A multi-item prosuction planning model with setup times : algorithms, reformulations and polyhedral characterizations for a special case

    OpenAIRE

    Miller, Andrew J.; Nemhauser, Georges L.; Savelsbergh, Martin

    2001-01-01

    We study a special case of a structured mixed integer programming model that arises in a number of applications. For the most general case of the model, called PI, we have earlier analyzed the polyhedral structure (Miller et al. [2000a]), including identifying facet-defining valid inequalities. PI is N P-hard; in this paper we focus on a special case, called PIC, that is polynomially solvable. We describe a polynomial algorithm for PIC, and we then use this algorithm to derive an extended for...

  9. A Nonsmooth L-M Method for Solving the Generalized Nonlinear Complementarity Problem over a Polyhedral Cone

    International Nuclear Information System (INIS)

    In this paper the generalized nonlinear complementarity problem (GNCP) defined on a polyhedral cone is reformulated as a system of nonsmooth equations. Based on this reformulation, the famous Levenberg-Marquardt (L-M) algorithm is employed to obtain its solution. Theoretical results that relate the stationary points of the merit function to the solution of the GNCP are presented. Under mild assumptions, we show that the L-M algorithm is both globally and superlinearly convergent.Moreover, a method to calculate a generalized Jacobian is given and numerical experimental results are presented

  10. Protein Content of Polyhedral Organelles Involved in Coenzyme B12-Dependent Degradation of 1,2-Propanediol in Salmonella enterica Serovar Typhimurium LT2†

    OpenAIRE

    Havemann, Gregory D.; Bobik, Thomas A.

    2003-01-01

    Salmonella enterica forms polyhedral organelles during coenzyme B12-dependent growth on 1,2-propanediol (1,2-PD). Previously, these organelles were shown to consist of a protein shell partly composed of the PduA protein, the majority of the cell's B12-dependent diol dehydratase, and additional unidentified proteins. In this report, the polyhedral organelles involved in B12-dependent 1,2-PD degradation by S. enterica were purified by a combination of detergent extraction and differential and d...

  11. Adsorption removal of Congo red from aqueous solution by polyhedral Cu2O nanoparticles: Kinetics, isotherms, thermodynamics and mechanism analysis

    International Nuclear Information System (INIS)

    Highlights: • Polyhedral Cu2O NPs with rough surfaces were prepared by a one-pot sonochemical precipitation method. • The Cu2O NPs show unprecedented adsorption capability toward Congo red. • CR adsorption onto Cu2O is a spontaneous, endothermic and chemisorption process. • The Cu2O adsorbent can be photocatalytically regenerated by visible light irradiation. - Abstract: Polyhedral cuprous oxide nanoparticles (Cu2O NPs) with rough surfaces were prepared by a one-pot sonochemical precipitation method. The products were characterized by SEM, XRD, EDS, XPS, and UV–Vis DRS, respectively. The adsorption behavior of Congo red (CR) from aqueous solution onto the as-prepared Cu2O NPs was systematically investigated. The equilibrium and kinetic studies suggested that the adsorption process followed Freundlich isotherm and pseudo-second order model, respectively. The as-prepared Cu2O NPs exhibited remarkable adsorption properties toward CR. The maximum adsorption capacity at 20 °C was 3904 mg g−1, which was the highest reported value so far in adsorption removal of CR. Together with the evaluation of the thermodynamic parameters such as Gibbs free energy, enthalpy and entropy change, our results show that the adsorption of CR onto Cu2O is a spontaneous, endothermic and chemisorption process. A putative interaction model between CR and Cu2O NPs was proposed. Moreover, the Cu2O adsorbent could be photocatalytically regenerated and reused without significant loss of its adsorption capability

  12. Deficiency of Starch Synthase IIIa and IVb Alters Starch Granule Morphology from Polyhedral to Spherical in Rice Endosperm.

    Science.gov (United States)

    Toyosawa, Yoshiko; Kawagoe, Yasushi; Matsushima, Ryo; Crofts, Naoko; Ogawa, Masahiro; Fukuda, Masako; Kumamaru, Toshihiro; Okazaki, Yozo; Kusano, Miyako; Saito, Kazuki; Toyooka, Kiminori; Sato, Mayuko; Ai, Yongfeng; Jane, Jay-Lin; Nakamura, Yasunori; Fujita, Naoko

    2016-03-01

    Starch granule morphology differs markedly among plant species. However, the mechanisms controlling starch granule morphology have not been elucidated. Rice (Oryza sativa) endosperm produces characteristic compound-type granules containing dozens of polyhedral starch granules within an amyloplast. Some other cereal species produce simple-type granules, in which only one starch granule is present per amyloplast. A double mutant rice deficient in the starch synthase (SS) genes SSIIIa and SSIVb (ss3a ss4b) produced spherical starch granules, whereas the parental single mutants produced polyhedral starch granules similar to the wild type. The ss3a ss4b amyloplasts contained compound-type starch granules during early developmental stages, and spherical granules were separated from each other during subsequent amyloplast development and seed dehydration. Analysis of glucan chain length distribution identified overlapping roles for SSIIIa and SSIVb in amylopectin chain synthesis, with a degree of polymerization of 42 or greater. Confocal fluorescence microscopy and immunoelectron microscopy of wild-type developing rice seeds revealed that the majority of SSIVb was localized between starch granules. Therefore, we propose that SSIIIa and SSIVb have crucial roles in determining starch granule morphology and in maintaining the amyloplast envelope structure. We present a model of spherical starch granule production. PMID:26747287

  13. Synthesis and characterization of polyhedral oligomeric titanized silsesquioxane: A new biocompatible cage like molecule for biomedical application.

    Science.gov (United States)

    Yahyaei, Hossein; Mohseni, Mohsen; Ghanbari, Hossein; Messori, Massimo

    2016-04-01

    Organic-inorganic hybrid materials have shown improved properties to be used as biocompatible coating in biomedical applications. Polyhedral oligomeric silsesquioxane (POSS) containing coatings are among hybrid materials showing promising properties for these applications. In this work an open cage POSS has been reacted with a titanium alkoxide to end cap the POSS molecule with titanium atom to obtain a so called polyhedral oligomeric metalized silsesquioxane (POMS). The synthesized POMS was characterized by FTIR, RAMAN and UV-visible spectroscopy as well as (29)Si NMR and matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) techniques. Appearance of peaks at 920cm(-1) in FTIR and 491cm(-1) and 1083cm(-1) in Raman spectra confirmed Si-O-Ti linkage formation. It was also demonstrated that POMS was in a monomeric form. To evaluate the biocompatibility of hybrids films, pristine POSS and synthesized POMS were used in synthesis of a polycarbonate urethane polymer. Results revealed that POMS containing hybrid, not only had notable thermal and mechanical stability compared to POSS containing one, as demonstrated by DSC and DMTA analysis, they also showed controlled surface properties in such a manner that hydrophobicity and biocompatibility were both reachable to give rise to improved cell viability in presence of human umbilical vein endothelial cells (HUVEC) and MRC-5 cells. PMID:26838853

  14. Polymer-modified copper catalysts on carbon-containing support for reactions of H2O2 decomposition and cyclohexane oxidation

    Directory of Open Access Journals (Sweden)

    S. Auezkhanova

    2012-12-01

    Full Text Available Polymer-copper catalysts supported on a carbon-containing sorbent(CS, obtained by rice husk pyrolysis have been studied in the reactions of hydrogen peroxide decomposition and cyclohexane oxidation by hydrogen peroxide at 40°C and atmospheric pressure. The effect of the polymer nature on the activity of the developed catalysts have been shown. Polyhexamethyleneguanidine (PHMG was an optimal modifier for the developed catalysts. The calculated number of catalytic cycles (TON for 7% Cu-PGMG/CS was 450.

  15. Thermal Stability and Ablation Behavior of Modified Polydimethylsiloxane-Based Polyurethane Composites Reinforced with Polyhedral Oligomeric Silsesquioxane.

    Science.gov (United States)

    Han, Zhongyou; Xi, Yukun; Kwon, Younghwan

    2016-02-01

    Series of polydimethylsiloxane (PDMS)-based polyurethane (PU)/polyhedral oligomeric silsesquioxane (POSS) composites are prepared using ether or polyether modified diol/polyol PDMS prepolymers, isophorone diisocyanate (IPDI) and either non-reactive or reactive POSS. The effect of POSS incorporated chemically or physically, number of ethylene oxide units and crosslinking on PDMS based PU is investigated in terms of thermal stability and ablation properties. The ablation property is measured using an oxyacetylene torch test, and the ablation rate is evaluated. The results show that POSS molecules make a considerable influence on the ablative resistance, because they act as protective silica forming precursors under oxyacetylene condition. POSS molecules, especially methyl POSS, in PU matrix leads to the formation of densely accumulated spherical silica layers on the top of the ablated surface, resulting in improved ablation resistance. PMID:27433703

  16. Crystallization and mechanical properties of biodegradable poly(p-dioxanone)/octamethyl-polyhedral oligomeric silsesquioxanes nanocomposites via simple solution casting method

    Indian Academy of Sciences (India)

    Zhecun Wang; Chengdong Xiong; Qing Li

    2015-10-01

    In this study, biodegradable poly(p-dioxanone) (PPDO)/octamethyl-polyhedral oligomeric silsesquioxanes (ome-POSS) nanocomposites were fabricated by the simple solution casting method with various ome-POSS loadings. Scanning electron microscopic observations indicate that ome-POSS is well dispersed in the PPDO matrix. Effect of ome-POSS on the isothermal melt crystallization and dynamic mechanical properties of PPDO in the nanocomposites were studied in detail. It shows that the overall crystallization rates are faster in the nanocomposites than in neat PPDO and increase with the increase in ome-POSS loadings; however, X-ray diffraction patterns, POM and the Avrami exponent suggest that the crystal structure and the crystallization mechanism do not change despite the presence of ome-POSS. The mechanical property of PPDO/ome-POSS nanocomposites was enhanced with respect to neat PPDO.

  17. Aqueous alteration of chondrules from the Murchison CM carbonaceous chondrite: Replacement, pore filling, and the genesis of polyhedral serpentine

    Science.gov (United States)

    Lee, M. R.; Lindgren, P.

    2016-04-01

    Forsterite and clinoenstatite in type IAB chondrules from the Murchison CM carbonaceous chondrite have been partially serpentinized, and the mechanisms of their alteration reveal crystallographic and microstructural controls on the reaction of silicate minerals with parent body aqueous solutions. Grains of forsterite were altered in two stages. Narrow veinlets of Fe-rich serpentine formed first and by the filling of sheet pores. Most of these pores were oriented parallel to (010) and (001) and had been produced by earlier fracturing and/or congruent dissolution. In the second stage, the subset of veinlets that were oriented parallel to (001) was widened accompanying the replacement of forsterite by Mg-Fe serpentine. This reaction proceeded most rapidly parallel to [001], and crystallographic controls on the trajectory of retreating vein walls created fine-scale serrations. Murchison clinoenstatite grains have a skeletal appearance due to the presence of abundant veinlets and patches of phyllosilicate. Two alteration stages can again be recognized, with initial water-mineral interaction producing tochilinite-rich veinlets by the filling of (001)-parallel contraction cracks. Pores then formed by congruent dissolution that was guided principally by orthopyroxene lamellae, and they were subsequently filled by submicrometer-sized crystals of polyhedral serpentine. This finding that Murchison forsterite and clinoenstatite grains have been altered demonstrates that aqueous processing of magnesium silicate minerals started much earlier in CM parent body history than previously believed. Our results also show that the occurrence of polyhedral serpentine can be used to locate former pore spaces within the parent body.

  18. Aqueous alteration of chondrules from the Murchison CM carbonaceous chondrite: Replacement, pore filling, and the genesis of polyhedral serpentine

    Science.gov (United States)

    Lee, M. R.; Lindgren, P.

    2016-06-01

    Forsterite and clinoenstatite in type IAB chondrules from the Murchison CM carbonaceous chondrite have been partially serpentinized, and the mechanisms of their alteration reveal crystallographic and microstructural controls on the reaction of silicate minerals with parent body aqueous solutions. Grains of forsterite were altered in two stages. Narrow veinlets of Fe-rich serpentine formed first and by the filling of sheet pores. Most of these pores were oriented parallel to (010) and (001) and had been produced by earlier fracturing and/or congruent dissolution. In the second stage, the subset of veinlets that were oriented parallel to (001) was widened accompanying the replacement of forsterite by Mg-Fe serpentine. This reaction proceeded most rapidly parallel to [001], and crystallographic controls on the trajectory of retreating vein walls created fine-scale serrations. Murchison clinoenstatite grains have a skeletal appearance due to the presence of abundant veinlets and patches of phyllosilicate. Two alteration stages can again be recognized, with initial water-mineral interaction producing tochilinite-rich veinlets by the filling of (001)-parallel contraction cracks. Pores then formed by congruent dissolution that was guided principally by orthopyroxene lamellae, and they were subsequently filled by submicrometer-sized crystals of polyhedral serpentine. This finding that Murchison forsterite and clinoenstatite grains have been altered demonstrates that aqueous processing of magnesium silicate minerals started much earlier in CM parent body history than previously believed. Our results also show that the occurrence of polyhedral serpentine can be used to locate former pore spaces within the parent body.

  19. Surface modification of a polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) nanocomposite polymer as a stent coating for enhanced capture of endothelial progenitor cells.

    OpenAIRE

    Tan, Aaron; Farhatnia, Yasmin; Goh, Debbie; Natasha, G; de Mel, Achala; Lim, Jing; Teoh, Swee-Hin; Malkovskiy, Andrey V; Chawla, Reema; Rajadas, Jayakumar; Cousins, Brian G; Michael R Hamblin; Alavijeh, Mohammad S; Seifalian, Alexander M

    2013-01-01

    An unmet need exists for the development of next-generation multifunctional nanocomposite materials for biomedical applications, particularly in the field of cardiovascular regenerative biology. Herein, we describe the preparation and characterization of a novel polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) nanocomposite polymer with covalently attached anti-CD34 antibodies to enhance capture of circulating endothelial progenitor cells (EPC). This material may ...

  20. Polyhedral metallathiaborane chemistry: Synthesis and characterisation of metallathiaboranes based on the twelve-vertex icosahedral closo-{MSB10H10} unit, where M is Rh or Ir

    Czech Academy of Sciences Publication Activity Database

    Macías, R.; Thornton-Pett, M.; Holub, Josef; Spalding, T. R.; Faridoon, Y.; Štíbr, Bohumil; Kennedy, J.D.

    2008-01-01

    Roč. 693, č. 3 (2008), s. 435-445. ISSN 0022-328X R&D Projects: GA MŠk LC523 Grant ostatní: EPSRC(GB) J/56929; EPSRC(GB) L/49505; EPSRC(GB) R/61949 Institutional research plan: CEZ:AV0Z40320502 Keywords : metallathiaborane * polyhedral chemistry Subject RIV: CA - Inorganic Chemistry Impact factor: 1.866, year: 2008

  1. Coating of Carbon Fiber with Polyhedral Oligomeric Silsesquioxane (POSS) to Enhance Mechanical Properties and Durability of Carbon/Vinyl Ester Composites

    OpenAIRE

    Mujib Khan; Mahesh Hosur; Hassan Mahfuz; Richard Granata; Felicia Powell

    2011-01-01

    Our continuing quest to improve the performance of polymer composites under moist and saltwater environments has gained momentum in recent years with the reinforcement of inorganic nanoparticles into the polymer. The key to mitigate degradation of composites under such environments is to maintain the integrity of the fiber/matrix (F/M) interface. In this study, the F/M interface of carbon/vinyl ester composites has been modified by coating the carbon fiber with polyhedral oligomeric silsesqui...

  2. Organic-inorganic hybrid proton exchange membrane based on polyhedral oligomeric silsesquioxanes and sulfonated polyimides containing benzimidazole

    Science.gov (United States)

    Pan, Haiyan; Zhang, Yuanyuan; Pu, Hongting; Chang, Zhihong

    2014-10-01

    A new series of organic-inorganic hybrid proton exchange membranes (PEMs) were prepared using sulfonated polyimides containing benzimidazole (SPIBIs) and glycidyl ether of polyhedral oligomeric silsesquioxanes (G-POSS). SPIBIs were synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 5-amino-2-(4-aminophenyl) benzimidazole (APBIA) and 4,4‧-diaminodiphenyl ether-2,2‧-disulfonic acid (ODADS). The organic-inorganic cross-linked membranes can be prepared by SPIBIs with G-POSS by a thermal treatment process. The cross-linking density of the membranes was evaluated by gel fractions. The water uptake, swelling ratio, mechanical property, thermal behavior, proton conductivity, oxidative and hydrolytic stability of the cross-linked organic-inorganic membranes were intensively investigated. All the cross-linked membranes exhibit high cross-linking density for the gel fraction higher than 70%. Compared to pristine membranes (SPIBIs) and membranes without benzimidazole groups (SPI), the anti-free-radical oxidative and hydrolytic stabilities of cross-linked membranes are significantly higher. The anti-free-oxidative stability of SPIBI-100-P (cross-linked SPIBI membrane with 100% degree of sulfonation) is nearly four-fold higher than that of SPIBI-100. The proton conductivity of the cross-linked membranes ranges from 10-3 S cm-1 to 10-2 S cm-1 depending both on the degree of sulfonation (DS) of the SPIBI and temperature.

  3. Highly stable nanofluid based on polyhedral oligomeric silsesquioxane-decorated graphene oxide nanosheets and its enhanced electro-responsive behavior

    Science.gov (United States)

    Li, Yizhuo; Guan, Yanqing; Liu, Yang; Yin, Jianbo; Zhao, Xiaopeng

    2016-05-01

    Graphene oxide (GO) shows potential as an anisotropic nanofiller or a dispersed phase of electro-responsive electrorheological (ER) nanofluid due to its small size and high aspect ratio. But it is difficult to disperse GO in non-polar oil due to the hydrophilic nature of GO and thus the resulting fluid is often subject to dispersion instability and low ER effect. These disadvantages largely limit the real application of GO-based ER nanofluid. In this paper, we develop the polyhedral oligomeric silsesquioxane (POSS)-decorated GO (POSS-GO) nanosheets and demonstrate that decorating with POSS overcomes the dispersion instability of GO in silicone oil and enhances the ER effect. The morphology and structure of samples are characterized by atomic force microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and x-ray photoelectronic spectroscopy. The results show that the POSS-GO nanosheets are ultrathin with ∼3 nm thickness and have good compatibility with silicone oil and, as a result, the nanofluid of POSS-GO nanosheets in silicone oil shows high dispersion stability. After standing for one year at room temperature, no sedimentation occurs. Under an external electric field, the ER efficiency of the POSS-GO nanofluid is ten times as high as that of the pure GO fluid. This enhanced electro-responsive behavior is related to the fact that decorating with POSS partly reduces the GO and compresses the dielectrophoretic effect of the negatively charged pure GO fluid.

  4. Fluorinated Polyhedral Oligomeric Silsesquioxane Based Giant Molecular Shape Amphiphiles: Hierarchical Self-Assembly with Unusual Chain Conformation

    Science.gov (United States)

    Dong, Xue-Hui; Bo NI Collaboration; Ziran Chen Collaboration; Yiwen Li Collaboration; Wen-Bin Zhang Collaboration; Stephen Z. D. Cheng Collaboration

    2014-03-01

    The fluorous phase has thus been considered as the third phase that repels both oil and water due to its ultra-low surface energy. Incorporation of fluorinated component into hydrophilic/hydrophobic polymers is anticipated to bring novel self-assembly behaviors in the bulk, solution and thin film states, which are not only academically intriguing but also technological relevant. Among them, fluorous molecular clusters are of particular interest. A topologic isomer pair of giant molecular shape amphiphiles can be constructed by tethering molecular nanoparticle at different location of block polymers. In this study, a fluorinated polyhedral oligomeric silsesquioxane (FPOSS) was precisely fixed onto polystyreneblockpoly(ethylene oxide) (PS- b-PEO) at chain end (FPOSS-PS- b-PEO), or junction point [PS-(FPOSS)-PEO]. The interplay between nanoparticle and block polymers results in hierarchical structures with three types of order. The incommensuration of cross-sectional area between FPOSS and block polymer stretches polymer chains, which found to enhance the immiscibility between PEO and PS block.

  5. Structural and electrochemical properties of polyurethanes/polyhedral oligomeric silsesquioxanes (PU/POSS) hybrid coatings on aluminum alloys

    International Nuclear Information System (INIS)

    Hybrid coatings based on polyurethanes/polyhedral oligomeric silsesquioxanes (PU/POSS) were synthesized through a sol-gel technique. Hydroxy-terminated polybutadiene (HTPB), isophoron diisocyanate (IPDI) and trans-cyclohexane diolisobuty-POSS (POSS) were used as precursors for the hybrid coatings. These hybrid films were deposited via spin coating onto an aluminum alloy in order to improve the corrosion protection. The effects induced by the POSS content on the structural, thermal properties and corrosion resistance of the coated samples were investigated. The structures of the obtained hybrid materials were characterized with gel permeation chromatograph (GPC), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The GPC, FTIR and XRD spectra suggested successful bonding of POSS silanols and polyurethane resin. The homogeneous dispersion of POSS cages in the PU matrices was evidenced by scanning electronic microscopy (SEM) and atomic force microscopy (AFM). Thermal properties of these PU/POSS hybrids have been improved over the pure polyurethane analyzed by dynamic mechanical analysis (DMA) and thermal gravimetric analysis (TGA). Potentio-dynamic and salt-spray analysis revealed that the hybrid films provided an exceptional barrier and corrosion protection in comparison with PU and untreated aluminum alloy substrates.

  6. Preparation and characterization of crosslinked poly(ε-caprolactone)/polyhedral oligomeric silsesquioxane nanocomposites by electron beam irradiation

    International Nuclear Information System (INIS)

    Highlights: ► The homogenously-mixed PCL/POSS nanocomposites were prepared by solution blending. ► The crosslinking of the nanocomposites was conducted by electron beam irradiation. ► The crosslinked nanocomposites showed the improved mechanical and thermal properties. ► This technique is useful to fabricate high-performance polymer nanocomposites. - Abstract: Crosslinked poly(ε-caprolactone)/polyhedral oligomeric silsesquioxane (PCL/POSS) nanocomposite films prepared by a solution casting were crosslinked by electron beam irradiation under various conditions. The results of the crosslinking degree measurement revealed that the crosslinking degree of the PCL/POSS nanocomposites reached to 74%, which depended on the POSS content and the absorbed dose. The results of the FE–SEM and EDX analyses revealed that the POSS was homogeneously dispersed in the PCL matrix. In comparison to the virgin PCL with a tensile strength of 20 MPa, the tensile strength of the crosslinked PCL/POSS nanocomposites increased to 25.8 MPa with an increasing POSS content and absorbed dose to 100 kGy, whereas their elongation-at-break was considerably reduced. The results of the dynamic mechanical analysis revealed that the crosslinked PCL/POSS nanocomposites had a higher heat resistance than the virgin PCL. Based on the results of the enzymatic degradation test, the biodegradability of the crosslinked PCL/POSS nanocomposites was significantly reduced in comparison to that of the virgin PCL.

  7. Preparation and characterization of crosslinked poly(butylene adipate-co-terephthalate)/polyhedral oligomeric silsesquioxane nanocomposite by electron beam irradiation

    International Nuclear Information System (INIS)

    The electron beam-induced crosslinking of poly(butylene adipate-co-terephthalate) (PBAT)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites was investigated in this study. PBAT/POSS nanocomposites prepared by a solution blending with various compositions were crosslinked by electron beam irradiation at various absorbed doses ranging from 20 to 200 kGy and their properties were characterized in terms of their degree of crosslinking, morphology, thermal and mechanical properties, and biodegradability. The results of the degree of crosslinking measurements revealed that PBAT/POSS nanocomposites were more effectively crosslinked than the pure PBAT and that the degree of crosslinking was dependent on the absorbed dose and POSS content. From the results of the FE-SEM and EDX analyses, the POSS was found to be uniformly dispersed in the PBAT matrix. Based on the results of the UTM, DMA, and TMA, the crosslinked PBAT/POSS nanocomposites exhibited much higher thermal and mechanical properties compared to those of the pure PBAT. - Highlights: ► Crosslinked PBAT/POSS nanocomposites were prepared by electron beam irradiation. ► The POSS as a nanofillers was homogeneously dispersed in the PBAT matrix. ► The crosslinked nanocomposites exhibited improved thermal and mechanical properties.

  8. Silver and Copper Complexes with closo-Polyhedral Borane, Carborane and Metallacarborane Anions: Synthesis and X-ray Structure

    Directory of Open Access Journals (Sweden)

    Varvara V. Avdeeva

    2016-05-01

    Full Text Available Synthesis and structure of silver and copper salts and complexes with polyhedral boron hydride anions, including closo-decaborate [B10H10]2−, closo-dodecaborate [B12H12]2−, 1-carba-closo- decaborate [1-CB9H10]−, carba-closo-dodecaborate [CB11H12]−, and cobalt bis(dicarbollide [3,3′-Co(1,2-C2B9H112]− anions and their derivatives, are reviewed. The complexes demonstrate a wide variety of structural types, relating to both the metal coordination environment and coordination modes of boron hydride anions. The latter can range from strong coordination via the polyhedron triangular face including formation of 3c-2e MHB bonds in the case of the [B10H10]2− dianion, the structure of which contains two four-coordinated boron atoms, to very weak M…H interactions with the hydride atoms in the case of bulky [3,3′-Co(1,2-C2B9H112]− monoanion.

  9. Fouling behaviors of polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes for engineering osmosis processes

    KAUST Repository

    Chen, Sicong

    2014-02-01

    This paper investigated the individual effects of reverse salt flux and permeate flux on fouling behaviors of as-spun and annealed polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes under forward osmosis (FO) and pressure retarded osmosis (PRO) processes. Two types of membrane fouling had been studied; namely, inorganic fouling (CaSO4·2H2O gypsum scaling) during FO operations and organic fouling (sodium alginate fouling) during PRO operations. It is found that gypsum scaling on the membrane surface may be inhibited and even eliminated with an increase in reverse MgCl2 flux due to competitive formations of MgSO4° and CaSO4·2H2O. In contrast, the increase of reverse NaCl flux exhibits a slight enhancement on alginate fouling in both FO and PRO processes. Comparing to the reverse salt flux, the permeate flux always plays a dominant role in fouling. Therefore, lesser fouling has been observed on the membrane surface under the pressurized PRO process than FO process because the reduced initial flux mitigates the fouling phenomena more significantly than the enhancement caused by an increase in reverse NaCl flux. © 2013 Elsevier B.V.

  10. Polyhedral shape model for terrain correction of gravity and gravity gradient data based on an adaptive mesh

    Science.gov (United States)

    Guo, Zhikui; Chen, Chao; Tao, Chunhui

    2016-04-01

    Since 2007, there are four China Da yang cruises (CDCs), which have been carried out to investigate polymetallic sulfides in the southwest Indian ridge (SWIR) and have acquired both gravity data and bathymetry data on the corresponding survey lines(Tao et al., 2014). Sandwell et al. (2014) published a new global marine gravity model including the free air gravity data and its first order vertical gradient (Vzz). Gravity data and its gradient can be used to extract unknown density structure information(e.g. crust thickness) under surface of the earth, but they contain all the mass effect under the observation point. Therefore, how to get accurate gravity and its gradient effect of the existing density structure (e.g. terrain) has been a key issue. Using the bathymetry data or ETOPO1 (http://www.ngdc.noaa.gov/mgg/global/global.html) model at a full resolution to calculate the terrain effect could spend too much computation time. We expect to develop an effective method that takes less time but can still yield the desired accuracy. In this study, a constant-density polyhedral model is used to calculate the gravity field and its vertical gradient, which is based on the work of Tsoulis (2012). According to gravity field attenuation with distance and variance of bathymetry, we present an adaptive mesh refinement and coarsening strategies to merge both global topography data and multi-beam bathymetry data. The local coarsening or size of mesh depends on user-defined accuracy and terrain variation (Davis et al., 2011). To depict terrain better, triangular surface element and rectangular surface element are used in fine and coarse mesh respectively. This strategy can also be applied to spherical coordinate in large region and global scale. Finally, we applied this method to calculate Bouguer gravity anomaly (BGA), mantle Bouguer anomaly(MBA) and their vertical gradient in SWIR. Further, we compared the result with previous results in the literature. Both synthetic model

  11. Highly porous CdO nanowires: preparation based on hydroxy- and carbonate-containing cadmium compound precursor nanowires, gas sensing and optical properties

    International Nuclear Information System (INIS)

    Highly porous cadmium oxide (CdO) nanowires have been prepared by calcining the hydroxy- and carbonate-containing cadmium compound precursor nanowires. The large-scale precursor nanowires were synthesized through a hydrothermal method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize and analyze the as-synthesized precursor nanowires as well as the calcined products. It was revealed that the wire-like morphology of the precursor was fundamentally retained during the process of calcination and the CdO nanowires obtained were polycrystalline with highly porous structures. In order to illustrate the formation mechanism of the porous structures, the morphology and composition evolutions of the precursor nanowires under different stages of the calcining process were further investigated via SEM, x-ray diffraction (XRD) and infrared (IR) absorbance spectroscopy. Gas sensing has been explored for the sensor device fabricated with highly porous CdO nanowires, which demonstrates that it has good response owing to its special structures and great selectivity to NOx. Furthermore, the UV-visible and photoluminescence spectra of highly porous CdO nanowires have also been investigated

  12. Novel heart valve prosthesis with self-endothelialization potential made of modified polyhedral oligomeric silsesquioxane-nanocomposite material.

    Science.gov (United States)

    Ghanbari, Hossein; Radenkovic, Dina; Marashi, Sayed Mahdi; Parsno, Shirin; Roohpour, Nima; Burriesci, Gaetano; Seifalian, Alexander M

    2016-06-01

    In the cardiovascular system, the endothelial layer provides a natural antithrombogenic surface on the inner portion of the heart and associated vessels. For a synthetic material therefore, the ability to attract and retain endothelial or endothelial progenitor cells (EPCs), ultimately creating a single endothelial layer on its surface, is of prime importance. The authors have developed a nanocomposite polymer, based on a combination of polyhedral oligomeric silsesquioxane nanoparticles and polycarbonate urea urethane (POSS-PCU), which is biocompatible and has been used in human for the world's first synthetic trachea, tear duct, and bypass graft. In this study, the authors modified the surface of this casted nanocomposite by grafting fibronectin derived bioactive peptides [glycine-arginine-glycine-aspartic acid-glycine (GRGDG) and lauric acid conjugated GRGDG (GRGDG-LA)] to enhance the endothelialization for using heart valves leaflets from circulating EPCs. Human peripheral blood mononuclear cells were separated using Ficoll-Paque centrifugation, with harvested EPCs purified using CD34 microbead labeling and magnetic-activated cell sorting. Cells were seeded onto 96 well plates coated with POSS-PCU, GRGDG/GRGDG-LA modified POSS-PCU and PCU polymers, for a period of 21 days. Cells were studied under light, confocal, and scanning electron microscope (SEM). Fluorescence-activated cell sorting was used to analyze cell surface markers. Cell attachment and proliferation was observed in all POSS-PCU samples, significantly higher than the activity seen within the control PCU polymers (p PCU. The cells expressed increasing levels of mature endothelial cell markers over time with a concurrent reduction in hematopoietic stem cell marker expression. SEM showed a mixed population of morphologically differentiated endothelial cells and EPCs. These results support the use of heart valve made with the POSS-PCU polymer and demonstrate that suitable chemical modification of this

  13. Polyhedrality in Orlicz spaces

    Czech Academy of Sciences Publication Activity Database

    Hájek, Petr Pavel; Johanis, M.

    2008-01-01

    Roč. 168, č. 1 (2008), s. 167-188. ISSN 0021-2172 R&D Projects: GA ČR GA201/04/0090 Institutional research plan: CEZ:AV0Z10190503 Keywords : Orlicz space * locally dependent on finitely many coordinates Subject RIV: BA - General Mathematics Impact factor: 0.625, year: 2008

  14. Preparation of Polyhedral Oligomeric Silsesquioxane Modified Polyurethane%多面体低聚倍半硅氧烷改性PU的制备

    Institute of Scientific and Technical Information of China (English)

    田春蓉; 王建华; 孙杰; 梁书恩; 程克梅

    2011-01-01

    采用多面体低聚倍半硅氧烷(POSS)对聚氨酯(PU)进行改性,并对改性PU的性能进行研究.结果表明:采用超声波分散法可将POSS均匀分散在PU基体中;八乙烯基POSS对PU具有较好的补强和增韧作用,而八苯基POSS对PU的补强作用不明显.%Polyurethane(PU) was modified by polyhedral oligomeric silsesquioxane(POSS) , and the properties of modified PU were investigated. The results showed that,POSS was uniformly dispersed in PU matrix by using ultrasonic dispersion method; octavinylsilsesquioxane(OVS) possessed preferable reinforcing and toughening effects, but octaphenylsilsesquioxane (OPS) had no significant reinforcing effect.

  15. A complementary electrochromic device based on polyaniline tethered polyhedral oligomeric silsesquioxane and poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonic acid)

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Shanxin [Temasek Laboratories, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553 (Singapore); Ma, Jan; Lu, Xuehong [Temasek Laboratories, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2009-12-15

    A high-contrast complementary electrochromic device based on polyaniline (PANI) tethered polyhedral oligomeric silsesquioxane (POSS) (POSS-PANI) and poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonic acid) (PEDOT:PSS) is assembled. The electrochromic properties, cyclic voltammetry behavior and coloration efficiency of the device are studied. Due to the loosely packed structure, POSS-PANI gives rise to a significantly higher electrochromic contrast, coloration efficiency and faster switching speed than PANI. Despite its high contrast, the combination of POSS-PANI with PEDOT:PSS still shows synergy in terms of contrast enhancement, which can be attributed to the additional driving force for the diffusion of dopants into PEDOT:PSS provided by the dedoping of POSS-PANI. (author)

  16. Adsorption removal of Congo red from aqueous solution by polyhedral Cu{sub 2}O nanoparticles: Kinetics, isotherms, thermodynamics and mechanism analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Jinxia [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002 (China); Wang, Zhonghua, E-mail: zhwangs@163.com [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002 (China); Huang, Yijiang; Huang, Ni [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002 (China); Ren, Chunguang [Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Zhang, Wei [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China)

    2015-06-05

    Highlights: • Polyhedral Cu{sub 2}O NPs with rough surfaces were prepared by a one-pot sonochemical precipitation method. • The Cu{sub 2}O NPs show unprecedented adsorption capability toward Congo red. • CR adsorption onto Cu{sub 2}O is a spontaneous, endothermic and chemisorption process. • The Cu{sub 2}O adsorbent can be photocatalytically regenerated by visible light irradiation. - Abstract: Polyhedral cuprous oxide nanoparticles (Cu{sub 2}O NPs) with rough surfaces were prepared by a one-pot sonochemical precipitation method. The products were characterized by SEM, XRD, EDS, XPS, and UV–Vis DRS, respectively. The adsorption behavior of Congo red (CR) from aqueous solution onto the as-prepared Cu{sub 2}O NPs was systematically investigated. The equilibrium and kinetic studies suggested that the adsorption process followed Freundlich isotherm and pseudo-second order model, respectively. The as-prepared Cu{sub 2}O NPs exhibited remarkable adsorption properties toward CR. The maximum adsorption capacity at 20 °C was 3904 mg g{sup −1}, which was the highest reported value so far in adsorption removal of CR. Together with the evaluation of the thermodynamic parameters such as Gibbs free energy, enthalpy and entropy change, our results show that the adsorption of CR onto Cu{sub 2}O is a spontaneous, endothermic and chemisorption process. A putative interaction model between CR and Cu{sub 2}O NPs was proposed. Moreover, the Cu{sub 2}O adsorbent could be photocatalytically regenerated and reused without significant loss of its adsorption capability.

  17. Micro-CT analysis and mechanical properties of Ti spherical and polyhedral void composites made with saccharose as a space holder material

    International Nuclear Information System (INIS)

    The paper describes the formation, morphology and mechanical properties of Ti void composites. The Ti void composites were made using 100 and 325 mesh Ti powder for solid scaffold formation. The spherical and polyhedral voids (pores) were formed using saccharose particles (table sugar) of different shapes. The Ti void composite morphology was investigated by microcomputed tomography and scanning electron microscopy. The Ti void composites of designed porosity of 50–70% were made. Compression test was applied for mechanical properties estimation. It has been found, that Ti void composites made from 100 mesh Ti and those having spherical pores have a higher strength and elastic modulus, i.e. for the designed porosity of 50% for 100 and 325 mesh Ti void composites, a compressive strength was 32.32 and 20.13 MPa, respectively. It has been shown that this is related to better sintering of the 100 mesh Ti powders compared with the 325 mesh Ti powders. A correlation between microcomputed tomography data and mechanical properties has also been shown. The Ti void composites, made with the use of saccharose as a space holder, described in this work should be a promising material for biomedical applications, where interconnected pores and good mechanical properties are required. - Highlights: • Ti scaffolds of the porosity of 50–70% were made. • Saccharose particles as space holder were applied. • The voids in the scaffolds were designed with spherical and polyhedral shape. • The scaffold structure was investigated by SEM and micro-CT. • Micro-CT data and mechanical properties of the Ti scaffold have been correlated

  18. 高温氧化物晶体界面非稳定性研究%Polyhedral Instability of High-temperature Oxide Crystal

    Institute of Scientific and Technical Information of China (English)

    金蔚青; 蔡丽霞; 潘志雷; 苗宇

    2000-01-01

    设计了一套模拟实验, 以获得关于晶体形态和界面非稳定性的差异的可靠数据,如高温溶液生长的骸晶和枝蔓晶. 这些实验是在高温实时观察装置(HITISOT)内进行的. 高温溶液晶体生长实验是在环形铂金丝炉圈内进行的. 炉圈直径为2mm. 铂金丝既起加热又起支撑熔体的作用. 选用KNbO3和Li2B4O7?的混合物进行晶体生长实验. 在只存在扩散机制的快速生长过程中,会形成不同的晶体不完整性,如晶面凹坑、骸晶和枝蔓晶. 采用淬火实验以分辨不同的KNbO3晶体形态,并用扫描电镜研究Li2B4O7溶体中KNbO3?晶体生长的形貌. 在一般情况下,当晶体在气液界面附近液相区成核时,会产?生晶体界面非稳定性. 导致晶体形状不稳定的溶液层的厚度为60. 通过扫描电镜观察,发现晶体在这一溶液层中由多面体晶变为枝蔓晶. 骸晶和枝蔓?晶的各向异性反映了KNbO3的立方特性,也反映了界面非稳定性是沿[110]晶?棱扩大的. [110]晶棱方向的分支证实了晶体生长形状的各向异性. 形成界面非?稳定性的临界尺寸为10. 与此相反,保持稳定的晶面形状是通过60厚度以下的溶液内的晶体生长来实现的. 晶体生长过程是由高温实时观察装置进行实时观察和记录的,并能观察到晶体固液界面处的热溶质对流(如微对流).%Model experiments were designed in order to obtain more reliable data on the diversity of some crystal forms and polyhedral instability-skeletal and dendritic growth in high 妕emperature solution growth. These experiments were performed by High Temperature In Situ Observation Technique. Most of our investigations on high temperature solution growth were performed in a loop-shaped Pt wire heater, having a diameter about 2mm. The Pt wire (0.2mm) was used to heat and suspend the solution. A mixture of KNbO3 (20wt%) and Li2B4O7 was chosen for growth. Rapid growth

  19. PduA Is a Shell Protein of Polyhedral Organelles Involved in Coenzyme B12-Dependent Degradation of 1,2-Propanediol in Salmonella enterica Serovar Typhimurium LT2†

    OpenAIRE

    Havemann, Gregory D.; Sampson, Edith M.; Bobik, Thomas A.

    2002-01-01

    Salmonella enterica forms polyhedral organelles involved in coenzyme B12-dependent 1,2-propanediol degradation. These organelles are thought to consist of a proteinaceous shell that encases coenzyme B12-dependent diol dehydratase and perhaps other enzymes involved in 1,2-propanediol degradation. The function of these organelles is unknown, and no detailed studies of their structure have been reported. Genes needed for organelle formation and for 1,2-propanediol degradation are located at the ...

  20. BA321, a novel carborane analog that binds to androgen and estrogen receptors, acts as a new selective androgen receptor modulator of bone in male mice.

    Science.gov (United States)

    Watanabe, Kenta; Hirata, Michiko; Tominari, Tsukasa; Matsumoto, Chiho; Endo, Yasuyuki; Murphy, Gillian; Nagase, Hideaki; Inada, Masaki; Miyaura, Chisato

    2016-09-01

    Carboranes are a class of carbon-containing polyhedral boron cluster compounds with globular geometry and hydrophobic surface that interact with hormone receptors such as estrogen receptor (ER) and androgen receptor (AR). We have synthesized BA321, a novel carborane compound, which binds to AR. We found here that it also binds to ERs, ERα and ERβ. In orchidectomized (ORX) mice, femoral bone mass was markedly reduced due to androgen deficiency and BA321 restored bone loss in the male, whilst the decreased weight of seminal vesicle in ORX mice was not recovered by administration of BA321. In female mice, BA321 acts as a pure estrogen agonist, and restored both the loss of bone mass and uterine atrophy due to estrogen deficiency in ovariectomized (OVX) mice. In bone tissues, the trabecular bone loss occurred in both ORX and OVX mice, and BA321 completely restored the trabecular bone loss in both sexes. Cortical bone loss occurred in ORX mice but not in OVX mice, and BA321 clearly restored cortical bone loss due to androgen deficiency in ORX mice. Therefore, BA321 is a novel selective androgen receptor modulator (SARM) that may offer a new therapy option for osteoporosis in the male. PMID:27402268

  1. Contribution to the reconstruction of scenes made of cylindrical and polyhedral objects from sequences of images obtained by a moving camera

    International Nuclear Information System (INIS)

    Environment perception is an important process which enables a robot to perform actions in an unknown scene. Although many sensors exist to 'give sight', the camera seems to play a leading part. This thesis deals with the reconstruction of scenes made of cylindrical and polyhedral objects from sequences of images provided by a moving camera. Two methods are presented. Both are based on the evolution of apparent contours of objects in a sequence. The first approach has been developed considering that camera motion is known. Despite the good results obtained by this method, the specific conditions it requires makes its use limited. In order to avoid an accurate evaluation of camera motion, we introduce another method allowing, at the same time, to estimate the object parameters and camera positions. In this approach, only is needed a 'poor' knowledge of camera displacements supplied by the control system of the robotic platform, in which the camera is embedded. An optimal integration of a priori information, as well as the dynamic feature of the state model to estimate, lead us to use the Kalman filter. Experiments conducted with synthetic and real images proved the reliability of these methods. Camera calibration set-up is also suggested to achieve the most accurate scene models resulting from reconstruction processes. (author)

  2. Surface modification of a polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) nanocomposite polymer as a stent coating for enhanced capture of endothelial progenitor cells.

    Science.gov (United States)

    Tan, Aaron; Farhatnia, Yasmin; Goh, Debbie; G, Natasha; de Mel, Achala; Lim, Jing; Teoh, Swee-Hin; Malkovskiy, Andrey V; Chawla, Reema; Rajadas, Jayakumar; Cousins, Brian G; Hamblin, Michael R; Alavijeh, Mohammad S; Seifalian, Alexander M

    2013-12-01

    An unmet need exists for the development of next-generation multifunctional nanocomposite materials for biomedical applications, particularly in the field of cardiovascular regenerative biology. Herein, we describe the preparation and characterization of a novel polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) nanocomposite polymer with covalently attached anti-CD34 antibodies to enhance capture of circulating endothelial progenitor cells (EPC). This material may be used as a new coating for bare metal stents used after balloon angioplasty to improve re-endothelialization. Biophysical characterization techniques were used to assess POSS-PCU and its subsequent functionalization with anti-CD34 antibodies. Results indicated successful covalent attachment of anti-CD34 antibodies on the surface of POSS-PCU leading to an increased propensity for EPC capture, whilst maintaining in vitro biocompatibility and hemocompatibility. POSS-PCU has already been used in 3 first-in-man studies, as a bypass graft, lacrimal duct and a bioartificial trachea. We therefore postulate that its superior biocompatibility and unique biophysical properties would render it an ideal candidate for coating medical devices, with stents as a prime example. Taken together, anti-CD34 functionalized POSS-PCU could form the basis of a nano-inspired polymer platform for the next generation stent coatings. PMID:24706135

  3. Hydrophobic interface controlled electrochemical sensing of nitrite based on one step synthesis of polyhedral oligomeric silsesquioxane/reduced graphene oxide nanocomposite.

    Science.gov (United States)

    Bai, Wushuang; Sheng, Qinglin; Zheng, Jianbin

    2016-04-01

    In this paper, we report a novel hydrophobic interface controlled electrochemical sensing of nitrite based on polyhedral oligomeric silsesquioxane/ reduced graphene oxide nanocomposite (POSS/rGO). The POSS/rGO is prepared by one step hydrothermal synthesis method, and characterized by transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), Zeta-potential measurement analyzer, electrochemical impedance spectroscopy (EIS) and zero current potential method respectively. Then the POSS/rGO composite is used to fabricate electrochemical sensor for nitrite detection. According to experimental results, it is found that under control of hydrophobic force, the current peak will be shifted to lower potential (0.72V) and the possible reason has been analyzed in manuscript. In addition, the POSS/rGO based sensor also has wide linear range (0.5μM to 120mM), low detection limit (0.08μM) and good selectivity. In a word, the hydrophobic force controlled detection in this paper will provide a new platform for electrochemical sensing. PMID:26838412

  4. Preparation of polyhedral oligomeric silsesquioxane-based hybrid monolith by ring-opening polymerization and post-functionalization via thiol-ene click reaction.

    Science.gov (United States)

    Liu, Zhongshan; Ou, Junjie; Lin, Hui; Wang, Hongwei; Dong, Jing; Zou, Hanfa

    2014-05-16

    A polyhedral oligomeric silsesquioxane (POSS) hybrid monolith was simply prepared by using octaglycidyldimethylsilyl POSS (POSS-epoxy) and cystamine dihydrochloride as monomers via ring-opening polymerization. The effects of composition of prepolymerization solution and polycondensation temperature on the morphology and permeability of monolithic column were investigated in detail. The obtained POSS hybrid monolithic column showed 3D skeleton morphology and exhibited high column efficiency of ∼71,000 plates per meter in reversed-phase mechanism. Owing to this POSS hybrid monolith essentially possessing a great number of disulfide bonds, the monolith surface would expose thiol groups after reduction with dithiothreitol (DTT), which supplied active sites to functionalize with various alkene monomers via thiol-ene click reaction. The results indicated that the reduction with DTT could not destroy the 3D skeleton of hybrid monolith. Both stearyl methylacrylate (SMA) and benzyl methacrylate (BMA) were selected to functionalize the hybrid monolithic columns for reversed-phase liquid chromatography (RPLC), while [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide (MSA) was used to modify the hybrid monolithic column in hydrophilic interaction chromatography (HILIC). These modified hybrid monolithic columns could be successfully applied for separation of small molecules with high efficiency. It is demonstrated that thiol-ene click reaction supplies a facile way to introduce various functional groups to the hybrid monolith possessing thiol groups. Furthermore, due to good permeability of the resulting hybrid monoliths, we also prepared long hybrid monolithic columns in narrow-bore capillaries. The highest column efficiency reached to ∼70,000 plates using a 1-m-long column of 75μm i.d. with a peak capacity of 147 for isocratic chromatography, indicating potential application in separation and analysis of complex biosamples. PMID:24725471

  5. Plasma Surface Modification of Polyhedral Oligomeric Silsequioxane-Poly(carbonate-urea) Urethane with Allylamine Enhances the Response and Osteogenic Differentiation of Adipose-Derived Stem Cells.

    Science.gov (United States)

    Chaves, Camilo; Alshomer, Feras; Palgrave, Robert G; Kalaskar, Deepak M

    2016-07-27

    This study present amino functionalization of biocompatible polymer polyhedral oligomeric silsequioxane-poly(carbonate-urea) urethane (POSS-PCU) using plasma polymerization process to induce osteogenic differentiation of adipose derived stem cells (ADSCs). Optimization of plasma polymerization process was carried out keeping cell culture application in mind. Thus, samples were rigorously tested for retention of amino groups under both dry and wet conditions. Physio-chemical characterization was carried out using ninhydrin test, X-ray photon spectroscopy, scanning electron microscopy, and static water contact analysis. Results from physio chemical characterization shows that functionalization of the amino group is not stable under wet conditions and optimization of plasma process is required for stable bonding of amino groups to the POSS-PCU polymer. Optimized samples were later tested in vitro in short and long-term culture to study differentiation of ADSCs on amino modified samples. Short-term cell culture shows that initial cell attachment was significantly (p PCU) compared to unmodified POSS-PCU. NH2-POSS-PCU samples also facilitates osteogenic differentiation of ADSCs as confirmed by immunological staining of cells for extracellular markers such as collagen Type I and osteopontin. Quantification of total collagen and ALP activity also shows significant (p PCU samples compared to unmodified POSS-PCU. A pilot study also confirms that these optimized amino modified POSS-PCU samples can further be functionalized using bone inducing peptide such as KRSR using conventional wet chemistry. This further provides an opportunity for biofunctionalization of the polymer for various tissue specific applications. PMID:27384590

  6. Coating of Carbon Fiber with Polyhedral Oligomeric Silsesquioxane (POSS to Enhance Mechanical Properties and Durability of Carbon/Vinyl Ester Composites

    Directory of Open Access Journals (Sweden)

    Mujib Khan

    2011-09-01

    Full Text Available Our continuing quest to improve the performance of polymer composites under moist and saltwater environments has gained momentum in recent years with the reinforcement of inorganic nanoparticles into the polymer. The key to mitigate degradation of composites under such environments is to maintain the integrity of the fiber/matrix (F/M interface. In this study, the F/M interface of carbon/vinyl ester composites has been modified by coating the carbon fiber with polyhedral oligomeric silsesquioxane (POSS. POSS is a nanostructured inorganic-organic hybrid particle with a cubic structure having silicon atoms at the core and linked to oxygen atoms. The advantage of using POSS is that the silicon atoms can be linked to a substituent that can be almost any chemical group known in organic chemistry. Cubic silica cores are ‘hard particles’ and are about 0.53 nm in diameter. The peripheral organic unit is a sphere of about 1–3 nm in diameter. Further, cubic structure of POSS remains intact during the polymerization process and therefore with appropriate functional groups, if installed on the fiber surface, would provide a stable and strong F/M interface. Two POSS systems with two different functional groups; namely, octaisobutyl and trisilanolphenyl have been investigated. A set of chemical and mechanical procedures has been developed to coat carbon fibers with POSS, and to fabricate layered composites with vinyl ester resin. Interlaminar shear and low velocity impact tests have indicated around 17–38% improvement in mechanical properties with respect to control samples made without the POSS coating. Saltwater and hygrothermal tests at various environmental conditions have revealed that coating with POSS reduces water absorption by 20–30% and retains the composite properties.

  7. Preparation and Characterization of Polyhedral Oligomeric Silsesquioxane-Containing, Titania-Thiol-Ene Composite Photocatalytic Coatings, Emphasizing the Hydrophobic-Hydrophilic Transition.

    Science.gov (United States)

    Jefferson, LaCrissia U; Netchaev, Anton D; Jefcoat, Jennifer A; Windham, Amber D; McFarland, Frederick M; Guo, Song; Buchanan, Randy K; Buchanan, J Paige

    2015-06-17

    Coatings prepared from titania-thiol-ene compositions were found to be both self-cleaning, as measured by changes in water contact angle, and photocatalytic toward the degradation of an organic dye. Stable titania-thiol-ene dispersions at approximately 2 wt % solids were prepared using a combination of high-shear mixing and sonication in acetone solvent from photocatalytic titania, trisilanol isobutyl polyhedral oligomeric silsesquioxane (POSS) dispersant, and select thiol-ene monomers, i.e., trimethylolpropane tris(3-mercaptopropionate) (TMPMP), pentaerythritol allyl ether (APE), and 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TTT). The dispersed particle compositions were characterized by DLS and TEM. The synthetic methods employed yield a strongly bound particle/POSS complex, supported by IR, 29Si NMR, and TGA. The factors of spray techniques, carrier solvent volatility, and particle size and size distributions, in combination, likely all contribute to the highly textured but uniform surfaces observed via SEM and AFM. Polymer composites possessed thermal transitions (e.g., Tg) consistent with composition. In general, the presence of polymer matrix provided mechanical integrity, without significantly compromising or prohibiting other critical performance characteristics, such as film processing, photocatalytic degradation of adsorbed contaminants, and the hydrophobic-hydrophilic transition. In all cases, coatings containing photocatalytic titania were converted from superhydrophobic to superhydrophilic, as defined by changes in the water contact angle. The superhydrophilic state of samples was considered persistent, since long time durations in complete darkness were required to observe any significant hydrophobic return. In a preliminary demonstration, the photocatalytic activity of prepared coatings was confirmed through the degradation of crystal violet dye. This work demonstrates that a scalable process can be found to prepare titania

  8. CARBON-CONTAINING COMPOSITES BASED ON METALS

    Directory of Open Access Journals (Sweden)

    VAGANOV V. E.

    2015-10-01

    Full Text Available Problem statement Among the developed technologies metal-composites production,a special place takes powder metallurgy, having fundamental differences from conventionally used foundry technologies. The main advantages of this technology are: the possibility of sensitive control, the structure and phase composition of the starting components, and ultimately the possibility of obtaining of bulk material in nanostructured state with a minimum of processing steps. The potential reinforcers metals include micro and nano-sized oxides, carbides, nitrides, whiskers. The special position is occupied with carbon nanostructures (CNS: С60 fullerenes, single-layer and multi-layer nanotubes, onions (spherical "bulbs", nano-diamonds and graphite,their properties are being intensively studied in recent years. These objects have a high thermal and electrical conductivity values, superelasticity, and have a strength approximate to the theoretical value, which can provide an obtaining composite nanomaterial with a unique set of physical and mechanical properties. In creation of a metal matrix composite nanomaterials (CM, reinforced by various CNS, a special attention should be given to mechanical activation processes (MA already at the stage of preparation of the starting components affecting the structure, phase composition and properties of aluminum-matrix composites. Purpose. To investigate the influence of mechanical activation on the structure and phase composition of aluminum-matrix composites. Conclusion. The results of the study of the structure and phase composition of the initial and mechanically activated powders and bulk-modified metal-composites are shown, depending on the type and concentration of modifying varieties CNS, regimes of MA and parameters of compaction. The study is conducted of tribological properties of Al-CNS OF nanostructured materials.

  9. Resistência à corrosão de pós metálicos em concretos refratários contendo elevado teor de carbono Corrosion resistance of metal powders in high-carbon containing castables

    Directory of Open Access Journals (Sweden)

    V. G. Domiciano

    2006-09-01

    Full Text Available Os benefícios proporcionados pela adição de carbono em concretos refratários têm ampliado a utilização destes materiais em aplicações siderúrgicas. Contudo, um dos problemas que ainda limita o emprego de concretos refratários contendo elevado teor de carbono é a corrosão de pós metálicos comumente empregados para conter a oxidação do carbono a altas temperaturas. Estudos preliminares mostraram que a corrosão das partículas metálicas é diretamente afetada pelas condições alcalinas promovidas pela presença de cimento. Diante disso, o objetivo deste trabalho foi avaliar o efeito da temperatura e a influência de diferentes agentes ligantes sobre a resistência à corrosão de pós metálicos (Al e Si em água e em concretos refratários contendo elevado teor de carbono. Para isso, foi empregada uma técnica capaz de detectar a liberação de gás H2 como produto da reação de corrosão dos metais. Os resultados obtidos revelaram a possibilidade de aplicação dos pós metálicos em concreto refratário através da escolha de um ligante apropriado.The benefits promoted by carbon addition in refractory castables have led to an increase in the use of such materials in the steel making industry. Nevertheless, one of the problems that still hinder the use of high-carbon-containing castables is the corrosion of metal powders commonly used to prevent carbon oxidation at high temperatures. Preliminary studies have pointed out that the metal powders corrosion within the castables is affected by the aggressive alkaline conditions promoted by cement hydration. The present work aimed to evaluate the effect of temperature as well as the influence of different binders on the corrosion resistance of Al and Si powders in water and in high-carbon containing castables. A technique able to detect the H2-gas release was used to identify the metal powders corrosion. The results revealed the possibility of applying Al or Si powders in these

  10. Research Progress on Metal-containing Polyhedral Oligomeric Silsesquioxanes%含金属笼型倍半硅氧烷的研究进展

    Institute of Scientific and Technical Information of China (English)

    曾碧榕; 许一婷; 罗伟昂; 戴李宗

    2012-01-01

    倍半硅氧烷作为催化剂载体硅胶表面结构与性能研究的模型,可以通过表征其表面反应性质来直观认识硅胶负载型催化剂的作用机制。过去几十年来,倍半硅氧烷的研究呈现飞跃式的发展态势,开发出许多新化合物和新合成方法,并在一些催化过程中得到应用。将倍半硅氧烷作为金属化合物的配体,极大地丰富了元素化学的内容。本文重点介绍了合成含金属笼型倍半硅氧烷的相关进展,同时介绍了含金属笼型倍半硅氧烷在聚合物材料应用中的研究。%Polyhedral oligomeric silsesquioxancs (POSS) is a kind of organic and inorganic hybrids molecules with cage-like nanostructure. Study on POSS has gained great interest and becomes a hot spot in the field of catalytic materials over the past decade. New synthetic approaches have been developed, and new complexes based on elements throughout the periodic table have been synthesized. Researchers have also developed many methods to incorporate silsesquioxanes into new materials. It showed that the metal-containing POSS complexes were models of silica immobilized with metal complexes, and could provide us an intimate knowledge of the reactions on the surface of silica support. This review introduces the development of the synthesis of metallasilsesquioxanes of main group and transition metals, and also presents the recent applications of metal-containing POSS in flame retardant polymers, photoelectric material and so on. In the future, the research will focus on the synthesis and characterization of novel metal-containing POSS compounds as well as their applications in the field of catalysts and functional materials.

  11. Electronic origin of the dependence of hydrogen bond strengths on nearest-neighbor and next-nearest-neighbor hydrogen bonds in polyhedral water clusters (H2O)n, n = 8, 20 and 24

    Energy Technology Data Exchange (ETDEWEB)

    Iwata, Suehiro; Akase, Dai; Aida, Misako; Xantheas, Sotiris S.

    2016-08-04

    The relative stability and the characteristics of the hydrogen bond networks in the cubic cages of (H2O)8, dodecahedral cages of (H2O)20,and tetrakaidodecahedral cages of (H2O)24 are studied. The charge-transfer and dispersion interaction terms of every pair of the hydrogen bonds are evaluated by using the perturbation theory based on the locally-projected molecular orbital (LPMO PT). Every water molecule and every hydrogen-bonded pair in polyhedral clusters are classified by the types of the adjacent molecules and hydrogen bonds. The relative binding energies among the polyhedral clusters are grouped by these classifications. The necessary condition for the stable conformers and the rules of the ordering of the relative stability among the isomers are derived from the analysis. The O–O distances and the pair-wise charge-transfer terms are dependent not only on the types of the hydrogen donor and acceptor waters but also on the types of the adjacent waters. This dependence is analyzed with Mulliken’s charge-transfer theory. The work is partially supported by the Grant-in-Aid for Science Research of JSPS (SI, DA, MA). SSX was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Battelle operates the Pacific Northwest National Laboratory for the US Department of Energy.

  12. Standard test method for the analysis of refrigerant 114, plus other carbon-containing and fluorine-containing compounds in uranium hexafluoride via fourier-transform infrared (FTIR) spectroscopy

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 This test method covers determining the concentrations of refrigerant-114, other carbon-containing and fluorine-containing compounds, hydrocarbons, and partially or completely substituted halohydrocarbons that may be impurities in uranium hexafluoride. The two options are outlined for this test method. They are designated as Part A and Part B. 1.1.1 To provide instructions for performing Fourier-Transform Infrared (FTIR) spectroscopic analysis for the possible presence of Refrigerant-114 impurity in a gaseous sample of uranium hexafluoride, collected in a "2S" container or equivalent at room temperature. The all gas procedure applies to the analysis of possible Refrigerant-114 impurity in uranium hexafluoride, and to the gas manifold system used for FTIR applications. The pressure and temperatures must be controlled to maintain a gaseous sample. The concentration units are in mole percent. This is Part A. 1.2 Part B involves a high pressure liquid sample of uranium hexafluoride. This method can be appli...

  13. Polyhedral Techniques in Combinatorial Optimization

    NARCIS (Netherlands)

    Aardal, K.I.; van Hoesel, S.

    1995-01-01

    Combinatorial optimization problems arise in several areas ranging from management to mathematics and graph theory. Most combinatorial optimization problems are compu- tationally hard due to the restriction that a subset of the variables have to take integral values. During the last two decades ther

  14. POSS基树枝状大分子的合成与应用%Synthesis and Application of Dendrimers Based on Polyhedral Oligomeric Silsesquioxanes

    Institute of Scientific and Technical Information of China (English)

    姚敏; 王嘉骏; 顾雪萍; 冯连芳

    2012-01-01

    Dendrimer is one type of macromolecules with well-defined, highly-branched and nano-scaled architectures, composed of three distinct domains: core, branches and terminal groups. Its potential functions and applications are explored based on the unique physical and chemical features due to special molecular architecture. Using polyhedral oligomerie silsesquioxanes (POSS) as the core of dendrimers is an effective and facile way to simplify the tedious repetitive steps of preparation and separation. Since POSS allows eight branches to radiate from a silicon-oxygen rigid cubic core, the dendrimers can be constructed in a well-controlled globular, three- dimensional framework, and large numbers of peripheral groups can be obtained at relatively low generation numbers. As a kind of novel nano-hybrid supermolecules, POSS-based dendrimers have attracted considerable interest in materials science. In this review, we briefly introduce the synthetic approaches of some typical POSS- based dendrimers categorized by the different chemical composition of branching units, and then focus on the potential functions and applications of this nano-hybrid material in the fields of catalysis, gene and drug delivery, liquid crystals, light harvesting and energy transfer. The specific and excellent properties imparted by the incorporation of POSS into dendrimers are also presented. Finally, the advances of POSS-based dendrimers are prospected.%树枝状大分子(dendrimer)是一种高度支化、纳米尺度的人工合成大分子,具有独特的物理化学性能和重要的应用前景。利用具有8个可官能化顶点的多面体低聚倍半硅氧烷(POSS)作为树枝状大分子的核心,可在一定程度上简化树枝状大分子繁琐的合成与分离过程,在低代数时就可获得较大的表面官能团密度,并使树枝状分子呈现球形对称结构。POSS基树枝状大分子结合了POSS和树枝状分子结构与性能的优势,是一类

  15. Tumor accumulation of ε-poly-lysines-based polyamines conjugated with boron clusters

    International Nuclear Information System (INIS)

    Boron Neutron Capture Therapy (BNCT) is one of the potent cancer radiotherapies using nuclear reaction between 10B atoms and the neutron. Whether BNCT will succeed or not depends on tumor selective delivery of 10B compounds. ε-Poly-L-lysine is a naturally occurring polyamine characterized by the peptide linkages between the carboxyl and ε-amino groups of L-lysine. Because of high safety ε-PLL is applied practically as a food additive due to its strong antimicrobial activity. In this study, we focus on a development of a novel polymeric delivery system for BNCT using biodegradable ε-PLL conjugated with 10B-containing clusters (BSH). This polymeric boron carrier will be expected to deliver safely and efficiently into tumor tissues based on Enhanced Permeability and Retention (EPR) effect.

  16. Synthesis of boron-cluster containing amino acids and preparation of their polymers

    OpenAIRE

    Slepukhina, Irina

    2006-01-01

    The first aim of this work was to prepare water soluble [B12H12]2- containing amino acids. This task was reached by using the ability of dodecaborate derivatives such as ammonio-undecahydro-closo-dodecaborate BNH3, hydroxo-undecahydro-closo-dodecaborate BOH and S-(2-cyanoethyl)-thio-undecahydro-closo-dodecaborate(2-)CE-BSH to undergo alkylation reactions. With this idea we used halogen substituted monoalkylated educts such as:- 4-Bromobutylacetamidodiethylmalonate. Alkylation reactions with B...

  17. Atomic-scale study of the role of carbon on boron clustering

    International Nuclear Information System (INIS)

    Boron (BF2, 20 keV, 3.14/cm2) and carbon (13 keV, 1015/cm2) implanted silicon annealed at 800 oC during 30 min or at 1000 oC during 10 s has been investigated using a laser-assisted wide-angle tomographic atom probe (LaWaTAP) instrument. Boron-silicon clusters containing ∼ 1.3 at.% of boron atoms have been observed in boron implanted silicon with a concentration exceeding the solubility limit. Often identified as BICs, they are interpreted as a metastable phase. Furthermore, addition of carbon clearly reduced the clustering of boron. This was interpreted as a diminution of boron diffusion or as an increase of the solubility limit of boron. Carbon-silicon clusters containing ∼ 1.5 at.% of carbon atoms were observed, maybe the precursors of the SiC phase.

  18. Conjugates of boron clusters with derivatives of natural chlorin and bacteriochlorin

    International Nuclear Information System (INIS)

    Conjugates of bacteriochlorin p and chlorin e6 with cobalt bis(dicarbollide) anion [3,3'-Co(1,2-C2B9H11)2]- were synthesized using different synthetic approaches. The boronated bacteriochlorin p was prepared by reaction of bacteriochlorin N-amino cycloimide with, bis(dicarbollide)-based carboxylic acid. The boronated chlorin e6 conjugates were obtained by both 'click reaction' of containing alkyne group chlorine with azide derivative of cobaltacarborane and reaction of chorin-based amines with cyclic oxonium derivative of cobalt bis(dicarbollide).

  19. Synthèse et Caractérisation de POSS (Polyhedral Oligomeric SilSesquioxane) greffé POE. Application aux Systèmes Epoxy-Amine à base Aqueuse

    OpenAIRE

    Nguyen, Thi Bich Viet

    2010-01-01

    Ce travail de thèse porte sur la synthèse et la caractérisation d'une nouvelle classe de tensioactif hybride organiques/inorganiques POSS (Polyhedral Oligomeric SilSesquioxane) greffé poly(oxyde d'éthylène), désigné POSS-POE. Ces composés ont été utilisés comme agent tensioactif dans l'élaboration de formulations époxy-amine à base aqueuse. Parmi les différentes voies de synthèse des POSS-POE étudiées, la voie qui consiste à greffer la chaîne POE et les groupements hydrophobe par hydrosilylat...

  20. Study on Nanometer Hybrid Low Dielectric Constant Materials from Polyhedral Oligosilsesquioixanes%多面体笼型倍半硅氧烷纳米杂化低介电材料的研究

    Institute of Scientific and Technical Information of China (English)

    徐洪耀; 严正权; 张超; 苏新艳; 光善仪

    2011-01-01

    多面体笼型倍半硅氧烷( POSS)由O-Si-O链接的纳米尺寸的笼型无机芯[(SiO1.5)n]和外围有机取代基团(活性或惰性)组成,这种独特的结构为杂化功能材料的制备提供了重要的平台与基础.本文从低介电材料结构对其件能的影响以及低介电性能的形成机理等方面综述了低介电材料的制备方法,尤其是POSS在低介电材料控制制备的研究进展,为该领域新材料的设计提供借鉴.%Polyhedral oligosilsesquioixanes(POSS) is a nanosized organic-inorganic hybrid molecule, which consists of a well-defined cage-like nano inorganic core[ (SiO1.5) ? ] surrounded by organic corner groups. The unique structure of POSS molecules provide an important platform for controllable preparation of hybrid nano-composites in molecular level dispersion. In this paper, the influence of hybrid molecular structure on properties and forming mechanism of low dielectric constant, in particular, the research progress of POSS-based nanocomposite low dielectric constant materials were summarized.

  1. Azaboranes (RNH2)B8H11NHR. A new type of boron cluster for possible use in BNCT

    International Nuclear Information System (INIS)

    This interesting group of novel, water-soluble (RNH2)B8H11NHR species can be regarded as new boron carriers with potential use in the synthesis of boron-rich compounds for application in BNCT. These azaboranes are synthesized by the reaction of B9H13(SMe2) with primary amines NH2R. (author)

  2. Strong magnetic coupling in a magnetically dilute f-electron insulator: A dysprosium boron-cluster compound

    Science.gov (United States)

    Mori, T.; Sahara, R.; Kawazoe, Y.; Yubuta, K.; Shishido, T.; Grin, Y.

    2013-05-01

    Unexpectedly strong magnetic coupling is observed in boride insulators containing the B12 icosahedra as a structural unit. We have successfully synthesized Dy0.74B22C2N, which takes the RB22C2N-type crystal structure. The Dy phase was previously thought to not be possible to form. Spin glass-like behavior was observed with a broad peak in the zero field cooled (ZFC) magnetic susceptibility at T ˜ 44 K, while a large divergence for ZFC and field cooled (FC) curves is observed. The Curie-Weiss constant is determined to be θ =-43.9 K, and this system is indicated to have the strongest magnetic coupling ever observed for any rare earth boride insulator. Electronic structure and chemical bonding calculations were also made. Conventional mechanisms for f-electron magnetism cannot explain the strong coupling observed, which further indicates that the B12 icosahedra is functioning as a novel mediator of magnetic interaction.

  3. Group field theories generating polyhedral complexes

    CERN Document Server

    Thürigen, Johannes

    2015-01-01

    Group field theories are a generalization of matrix models which provide both a second quantized reformulation of loop quantum gravity as well as generating functions for spin foam models. While states in canonical loop quantum gravity, in the traditional continuum setting, are based on graphs with vertices of arbitrary valence, group field theories have been defined so far in a simplicial setting such that states have support only on graphs of fixed valency. This has led to the question whether group field theory can indeed cover the whole state space of loop quantum gravity. In this contribution based on [1] I present two new classes of group field theories which satisfy this objective: i) a straightforward, but rather formal generalization to multiple fields, one for each valency and ii) a simplicial group field theory which effectively covers the larger state space through a dual weighting, a technique common in matrix and tensor models. To this end I will further discuss in some detail the combinatorial ...

  4. Hygroscopicity of Black-Carbon-Containing Aerosol in Wildfire Plumes

    Science.gov (United States)

    Perring, A. E.; Schwarz, J. P.; Markovic, M. Z.; Fahey, D. W.; Yokelson, R. J.; Jimenez, J. L.; Campuzano Jost, P.; Day, D. A.; Palm, B. B.; Wisthaler, A.; Ziemba, L. D.; Anderson, B. E.; Diskin, G. S.; Huey, L. G.; Gao, R. S.

    2015-12-01

    Water uptake by black carbon (BC) containing aerosol has been quantified in wildfire plumes of varying age (from 1 to ~40 hr old) sampled in North America during the NASA SEAC4RS mission of 2013. Measurements were made in flight using parallel single-particle soot photometers (SP2) that simultaneously detected the BC component of the ambient aerosol ensemble under contrasting humidity conditions. The hygroscopicity parameter, κ, of material internally mixed with BC derived from this data set is consistent with previous estimates of bulk aerosol hygroscopicity from biomass burning sources. We explore the temporal evolution of κ during aging of the Yosemite Rim Fire plume to constrain the rate of conversion of BC-containing aerosol from hydrophobic to hydrophilic modes in these emissions. We also investigate the relationship between κ values for BC-containing particles and the oxidation state and hygroscopicity of the bulk aerosol. These observations have implications for BC transport and removal in biomass burning plumes and provide important constraints on model treatment of BC optical and microphysical properties from wildfire sources in ambient conditions.

  5. On the practical application of carbon-containing nanocomposites

    OpenAIRE

    Vaganov, V. Ye.

    2015-01-01

    Raising of problem. The ever increasing demand for low-quality packaging materials for the food and pharmaceutical industries has led to the creation of mnogotonazhnyh production of polyethylene terephthalate (PETF) and thus necessitated their subsequent disposal or recycling. One promising avenue is to provide utilization of recycled polymer fibers and the subsequent production of a nonwoven fabric having a tremendous prospects for use in construction, engineering and so on. The main problem...

  6. Sublimation properties in carbon containing tungsten-rhenium single crystals

    International Nuclear Information System (INIS)

    Data on sublimation parameters of W-Re single crystals with Re contents varying from 0.1 to 4.2 at % and different quantity of C, are obtained by the Langmuir method at superhigh vacuum. It is shown that the rates of sublimation in specimens with lesser carbon content (4.6X10-2 % at) increase with Re concentration growth (from 2.6 to 3.8% at) and sublimation parameters in specimens with greater carbon content (1.2x10-1 - 1.5x10-1% at) decrease in comparison with W(C=1.5x10-2 % at). The anisotropy of rate and heat of sublimation is observed in equivalent crystallographic directions , one of them is perpendicular to the crystallization direction. Another one - parallel to it. The effects observed are explained by the increase of C solubility in Re and by its redistribution in W bcc - lattice with a temperature increase

  7. Sublimation properties in carbon containing tungsten-rhenium single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dekhtyar, I.Ya.; Kolesnik, V.N.; Patoka, V.I.; Ovsienko, D.E.; Silant' ev, V.I.; Sosnina, E.I. (AN Ukrainskoj SSR, Kiev. Inst. Metallofiziki)

    Data on sublimation parameters of W-Re single crystals with Re contents varying from 0.1 to 4.2 at % and different quantity of C, are obtained by the Langmuir method at superhigh vacuum. It is shown that the rates of sublimation in specimens with lesser carbon content (4.6X10/sup -2/ % at) increase with Re concentration growth (from 2.6 to 3.8% at) and sublimation parameters in specimens with greater carbon content (1.2x10/sup -1/ - 1.5x10/sup -1/% at) decrease in comparison with W(C=1.5x10/sup -2/ % at). The anisotropy of rate and heat of sublimation is observed in equivalent crystallographic directions <100>, one of them is perpendicular to the crystallization direction. Another one - parallel to it. The effects observed are explained by the increase of C solubility in Re and by its redistribution in W bcc - lattice with a temperature increase.

  8. Separation of actinides and fission products from carbonate containing streams

    International Nuclear Information System (INIS)

    The capacities of the anion exchange resins AG 1-X8, AG 2-X8 and Bio-Rex 5 were determined for the carbonato complexes of UO22+, NpO22+, PuO22+, Pu4+, AmO22+ and Am3+ in batch and dynamic experiments. The Bio-Rex 5 resin, used for the first time in such experiments, shows a clear superiority over the strong basic resins which have been used in the treatment of uranium ores. The influence of the ratio U : CO32-, the pH-value, the temperature, the equilibration of the resin, the contact time and the concentration of uranium to the column parameters distribution coefficient, hold back- and break through capacities have been investigated for batch and dynamic experiments. The best results were obtained for a medium with pH 6-8 and low concentrations of actinides and carbonate ions, 0.04 M and 0.12 M respectively. In order to obtain informaiton on the behaviour of the fission products occuring in the recovery of the organic phase of the Purex-process, these expected fission products were added to the uranium solution, fixed and eluted together with the uranium and Bio-Rex 5. (orig./HK)

  9. Structural, electronic, and magnetic properties of boron cluster anions doped with aluminum:BnAlˉ (2 ≤ n ≤ 9)

    Institute of Scientific and Technical Information of China (English)

    Gu Jian-Bing; Yang Xiang-Dong; Wang Huai-Qian; Li Hui-Fang

    2012-01-01

    The geometrical structures,relative stabilities,electronic and magnetic properties of small BnAlˉ (2 ≤ n ≤ 9) clusters are systematically investigated by using the first-principles density functional theory.The results show that the Al atom prefers to reside either on the outer-side or above the surface,but not in the centre of the clusters in all of the most stable BnAlˉ (2 ≤ n ≤ 9) isomers and the one excess electron is strong enough to modify the geometries of some specific sizes of the neutral clusters.All the results of the analysis for the fragmentation energies,the second-order difference of energies,and the highest occupied-lowest unoccupied molecular orbital energy gaps show that B4Alˉ and B8Alˉ clusters each have a higher relative stability.Especially,the B8Alˉ cluster has the most enhanced chemical stability.Furthermore,both the local magnetic moments and the total magnetic moments display a pronounced oddeven oscillation with the number of boron atoms,and the magnetic effects arise mainly from the boron atoms except for the B7Alˉ and B9Alˉ clusters.

  10. Distance bound for nonconvex polyhedral models in close proximity

    OpenAIRE

    Jiménez Schlegl, Pablo; Torras, Carme

    2006-01-01

    In many applications, it suffices to know a lower bound on the distance between objects, instead of the exact distance itself, which may be more difficult to compute. Such an easy-to-compute lower bound on the distance between two nonconvex polyhedra is presented here, which does not require a decomposition of the original polyhedra into convex entities. Furthermore, a suitable preprocessing of the polyhedra permits lowering the effort needed to compute this lower bound, and improves its qual...

  11. Polyhedral Computations for the Simple Graph Partitioning Problem

    DEFF Research Database (Denmark)

    Sørensen, Michael Malmros

    The simple graph partitioning problem is to partition an edge-weighted graph into mutually disjoint subgraphs, each containing no more than b nodes, such that the sum of the weights of all edges in the subgraphs is maximal. In this paper we present a branch-and-cut algorithm for the problem that ...

  12. Reconstruction of 3D morphology of polyhedral nanoparticles

    International Nuclear Information System (INIS)

    The three-dimensional (3D) faceting morphology of ceria nanoparticles is analysed using transmission electron microscopy (TEM)-based computed tomography on the nanometre scale. A novel tomography mode of electron energy loss spectroscopic imaging using a single energy window for inelastically scattered electrons is introduced and found to be reliable and fast for freestanding nanoparticles. To compare the new tomographic method with other methods, we provide the first comprehensive application of three complementary TEM-based imaging techniques, including bright field TEM and annular dark field specific TEM (STEM). Traditional bright-field TEM tomography is found to be applicable, in spite of obvious artefacts, for crystalline particles of constant composition. However, the safest interpretation is achieved by a combined recording of bright field and spectroscopic images

  13. Design of HIV protease inhibitors based on inorganic polyhedral metallacarboranes

    Czech Academy of Sciences Publication Activity Database

    Řezáčová, Pavlína; Pokorná, Jana; Brynda, Jiří; Kožíšek, Milan; Cígler, Petr; Lepšík, Martin; Fanfrlík, Jindřich; Řezáč, Jan; Grantz Šašková, Klára; Sieglová, Irena; Plešek, Jaromír; Šícha, Václav; Grüner, Bohumír; Oberwinkler, H.; Sedláček, Juraj; Kräusslich, H. G.; Hobza, Pavel; Král, V.; Konvalinka, Jan

    2009-01-01

    Roč. 52, č. 22 (2009), s. 7132-7141. ISSN 0022-2623 R&D Projects: GA AV ČR IAAX00320901; GA MŠk LC512; GA MŠk LC523 EU Projects: European Commission(XE) 37693 - HIV PI RESISTANCE Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50520514; CEZ:AV0Z40320502 Keywords : HIV protease inhibitors * aspartic proteases * viral resistance * cobalt bis(dicarbollide) * crystal structure Subject RIV: CC - Organic Chemistry Impact factor: 4.802, year: 2009

  14. Polyhedral Interpolation for Optimal Reaction Control System Jet Selection

    Science.gov (United States)

    Gefert, Leon P.; Wright, Theodore

    2014-01-01

    An efficient algorithm is described for interpolating optimal values for spacecraft Reaction Control System jet firing duty cycles. The algorithm uses the symmetrical geometry of the optimal solution to reduce the number of calculations and data storage requirements to a level that enables implementation on the small real time flight control systems used in spacecraft. The process minimizes acceleration direction errors, maximizes control authority, and minimizes fuel consumption.

  15. Design of HIV Protease Inhibitors Based on Inorganic Polyhedral Metallacarboranes

    Energy Technology Data Exchange (ETDEWEB)

    Rezacova, Pavlina; Pokorna, Jana; Brynda, Ji; Kozisek, Milan; Cigler, Petr; Lesik, Martin; Fanfrlik, Jindrich; Rezac, Jan; Saskova, Klara Grantz; Sieglova, Irena; Plesek, Jaromir; Sicha, Vaclav; Gruner, Bohumir; Oberwinkler, Heike; Sedlacek, Juraj; Krausslich, Hans-Georg; Hobza, Pavel; Kral, Vladimir; Konvalinka, Jan; (Heidelberg); (ASCR-ICP); (ICT-Czech)

    2010-04-19

    HIV protease (HIV PR) is a primary target for anti-HIV drug design. We have previously identified and characterized substituted metallacarboranes as a new class of HIV protease inhibitors. In a structure-guided drug design effort, we connected the two cobalt bis(dicarbollide) clusters with a linker to substituted ammonium group and obtained a set of compounds based on a lead formula [H{sub 2}N-(8-(C{sub 2}H{sub 4}O){sub 2}-1,2-C{sub 2}B{sub 9}H{sub 10})(1',2'-C{sub 2}B{sub 9}H{sub 11})-3,3'-Co){sub 2}]Na. We explored inhibition properties of these compounds with various substitutions, determined the HIV PR:inhibitor crystal structure, and computationally explored the conformational space of the linker. Our results prove the capacity of linker-substituted dual-cage cobalt bis(dicarbollides) as lead compounds for design of more potent inhibitors of HIV PR.

  16. CSG Feature Trees from Engineering Sketches of Polyhedral Shapes

    OpenAIRE

    Plumed Ferrer, Raquel; Varley, Peter Ashley Clifford; Company, Pedro

    2014-01-01

    We investigate the problem of determining design intent from engineering sketches: what did the designer have in mind when sketching a component? Specifically, we consider the unidirectional reverse mapping from form features, as determined from an input sketch, to design features, representing the design intent present in the designer’s mind. We introduce a list of com- mon engineering form features. For each, we list which geometrical cues may be helpful in identifying these features in des...

  17. The number of polyhedral (3-connected planar) graphs

    NARCIS (Netherlands)

    Duijvestijn, A.J.W.; Federico, P.J.

    1981-01-01

    Data is presented on the number of 3-connected planar graphs, isomorphic to the graphs of convex polyhedra, with up to 22 edges. The numbers of such graphs having the same number of edges, and the same number of vertices and faces, are tabulated. Conjectured asymptotic formulas by W. T. Tutte and by

  18. The number of polyhedral (3-Connected Planar) Graphs

    NARCIS (Netherlands)

    Duijvestijn, A.J.W.

    1996-01-01

    Data is presented on the number of 3-connected planar graphs, isomorphic to the graphs of convex polyhedra, with up to 26 edges. Results have been checked with the the number of rooted c-nets of R.C. Mullin and P.J. Schellenberg and Liu Yanpei.

  19. Formic Acid Oxidation over Hierarchical Porous Carbon Containing PtPd Catalysts

    Directory of Open Access Journals (Sweden)

    Elena Pastor

    2013-10-01

    Full Text Available The use of high surface monolithic carbon as support for catalysts offers important advantage, such as elimination of the ohmic drop originated in the interparticle contact and improved mass transport by ad-hoc pore design. Moreover, the approach discussed here has the advantage that it allows the synthesis of materials having a multimodal porous size distribution, with each pore size contributing to the desired properties. On the other hand, the monolithic nature of the porous support also imposes new challenges for metal loading. In this work, the use of Hierarchical Porous Carbon (HPC as support for PtPd nanoparticles was explored. Three hierarchical porous carbon samples (denoted as HPC-300, HPC-400 and HPC-500 with main pore size around 300, 400 and 500 nm respectively, are used as porous support. PtPd nanoparticles were loaded by impregnation and subsequent chemical reduction with NaBH4. The resulting material was characterized by EDX, XRD and conventional electrochemical techniques. The catalytic activity toward formic acid and methanol electrooxidation was evaluated by electrochemical methods, and the results compared with commercial carbon supported PtPd. The Hierarchical Porous Carbon support discussed here seems to be promising for use in DFAFC anodes.

  20. A review of the interference of carbon containing fly ash with air entrainment in concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard; Jensen, Anker Degn; Skjøth-Rasmussen, Martin Skov;

    2008-01-01

    Industrial utilization of fly ash from pulverized coal combustion plays an important role in environmentally clean and cost effective power generation. Today, the primary market for fly ash utilization is as pozzolanic additive in the production of concrete. However, the residual carbon in fly ash...... work carried out to identify the mechanisms causing the interactions between AEAs and fly ash in concrete mixtures, emphasizing the residual carbon. It has been shown that not only the amount, but also the properties of carbon, such as particle size and surface chemistry, has an impact on the......-treatment methods applied to improve fly ash quality are described in the review. Ozonation, thermal treatment and physical cleaning of carbon have been found to improve the fly ash performance for concrete utilization. Ultimately, recommendations for further work are outlined in the discussion....

  1. Processing and properties of carbon containing silicon nitride ceramics derived from the pyrolysis of polyhydridochlorosilazanes

    International Nuclear Information System (INIS)

    The pyrolysis reactions of a polyhydridochlorosilazane and ESCA-investigations of the produced amorphous silicon carbonitride powders are reported. The as produced powder crystallizes to β-Si3N4 and β-SiC in the presence of a glassy phase containing Y2O3 and Al2O3. During pressureless sintering of the silicon carbonitride powder dense Si3N4/SiC-composits can be obtained. The microstructure of gas pressure sintered samples (10 MPa, 1900 C) shows elongated Si3N4 grains and equiaxial SiC particles. The crack path reveals the formation of elastic bridges resulting in a relatively high fracture toughness of about 10 MPa.m1/2. (orig.)

  2. Features of the interaction of alumina and silica with carbon-containing reducing agents

    Energy Technology Data Exchange (ETDEWEB)

    Kondratenko, A.P.

    1976-01-01

    In the mining of Ekibastuz coals, a rock containing 35 to 49% of coal substance and 60 to 65% of mineral fractions, mainly silica and alumina, is sent to the waste dump. When this rock is heated in an inert atmosphere above 1500 C the alumina and silica are reduced by the carbon present, as a result of which, in prinicple, it is possible to obtain a number of valuable products. These reactions are discussed.

  3. Decontamination of carbonate containing process streams in a reprocessing plant by chromatography

    International Nuclear Information System (INIS)

    Results of a new procedure are presented to decontaminate carbonate process streams containing fission products and actinides occurring in burned up fuel elements combining a filtration and chromatographic step. First the unsoluble or hydrolysed plutonium and fission product species are separated by a filter mounted in front of a Bio-Rex 5 resin column which fixes all activities remaining in the filtrate. The solution passing the column is decontaminated greater than 99%. The recovery of the actinides and fission products from the resin and the filter is performed by 4 M nitric acid. (orig./PW)

  4. Anisotropy of sublimation from equivalent crystal faces of carbon-containing tungsten monocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Dekhtyar, I.Ya.; Kolesnik, V.N.; Ovsienko, D.E.; Patoka, V.I.; Silant' ev, V.I.; Sosnina, E.I. (AN Ukrainskoj SSR, Kiev. Inst. Metallofiziki)

    1981-08-01

    Anisotropy of sublimation parameters was found in equivalent faces (100) or (1O0) of W single crystals oriented perpendicular or parallel to the growth direction. The anisotropy value depends on C concentration in W single crystals.

  5. Anisotropy of sublimation from equivalent crystal faces of carbon-containing tungsten monocrystals

    International Nuclear Information System (INIS)

    Anisotropy of sublimation parameters was found in equivalent faces (100) or (1O0) of W single crystals oriented perpendicular or parallel to the growth direction. The anisotropy value depends on C concentration in W single crystals

  6. Experimental evaluation of biomass burning emissions: Nitrogen and carbon containing compounds

    International Nuclear Information System (INIS)

    Data are presented on the nitrogen and carbon emissions of biomass burning. The results of the authors' experiments enable them to calculate new source strengths for many compounds, considering different burning stages and fire conditions on the one hand, and different fuel types and properties, on the other hand. They also presented a method for balancing elemental budgets of fires, which had already been described for carbon compounds by other authors but which is new for the nitrogen inventory. Based on their measurements they show that biomass burning contributes significantly to the global budgets of HCN, CH3CN (possibly the major source), NOx (12%), CO(22%), C2 to C4 hydrocarbons (14%), CH3Cl(41%), and probably also to the global source of C1-C5 aliphatic amines. Further, pyrogenic CO2 amounts are likely to represent a substantial contribution to the global greenhouse warming. An important result, from the study is the identification of N2 emissions, which causes a significant loss of fixed nitrogen (pyro-denitrification) in tropical ecosystems in the order of 5% to 20% of the global nitrogen fixation rate. Because of an interesting interplay between an enhanced postfire nitrogen fixation and an enhanced postfire N2O emission, it is not yet known if losses due to pyro-denitrification are balanced by nitrogen fixation

  7. Kinetic study of the reaction of uranium with various carbon-containing gases

    International Nuclear Information System (INIS)

    The kinetic study of the reaction U + CO2 and U + CO has been performed by a thermogravimetric method on a spherical uranium powder, in temperature ranges respectively from 460 to 690 deg. C and from 570 to 850 deg. C. The reaction with carbon dioxide leads to uranium dioxide. A carbon deposition takes place at the same time. The global reactions is the result of two reactions: U + 2 CO2 → UO2 + 2 CO U + CO2 → UO2 + C The reaction with carbon monoxide leads to a mixture of dioxide UO2, dicarbide UC2 and free carbon. The main reaction can be written. U + CO → 1/2 UO2 + 1/2 UC2 The free carbon results of the disproportionation of the carbon monoxide. A remarkable separation of the two phases UO2 and UC2 can be observed. A mechanism accounting for the phenomenon has been proposed. The two reactions U + CO2 and U + CO begin with a long germination period, after which, the reaction velocity seems to be limited in both cases by the ionic diffusion of oxygen through the uranium dioxide. (author)

  8. Wear resistant composite structure of vitreous carbon containing convoluted fibers. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Burton, R.G.; Burton, R.A.

    1996-05-28

    Energy Related Inventions Program Number 613 was a two year program to commercialize a unique new wear material, Metal Reinforced Carbon Composite, MRCC. The program was designed to manufacture sample components of MRCC for evaluation by potential users and manufacturers. As a result of the program Burton Technologies Inc. and Rotary Power International are forming a joint company to manufacture, market and license MRCC materials to a wide range of industries.

  9. Impact of composite structure and morphology on electronic and ionic conductivity of carbon contained LiCoO2 cathode

    OpenAIRE

    Kwon, Nam Hee; Yin, Hui; Brodard, Pierre; Sugnaux, Claudia; Fromm, Katharina M.

    2014-01-01

    Cathodes in lithium ion batteries consist of an ionic conductor, an electronic conductor and a binder in order to make a composite that is both electronically and ionically conductive. The carbon coating on the cathode material plays a critical role for the electrochemical properties of lithium ion batteries due to the increased electronic conductivity. We explain the relationship between the electrochemical properties and the characteristics of composites prepared using the ball-milling proc...

  10. A reliable light scattering computing for black carbon-containing particles: Hybrid discrete dipole approximation (h-DDA)

    Science.gov (United States)

    Moteki, N.

    2015-12-01

    Black carbon (BC) is a light-absorbing carbonaceous aerosol emitted from combustions of fossil fuels and biomasses and is estimated as the second most important contributor to positive climate forcing after the carbon dioxide. In the atmosphere, the fractal aggregate of BC-spherules may be mixed with non-absorbing (or weakly absorbing) compounds that forms morphologically complex "BC-containing particle". A reliable scattering code for BC-containing particles is necessary for predicting mass absorption efficiency of BC and designing/evaluating optical techniques for estimating microphysical properties (i.e., size distribution, mixing state, shape, refractive index) of BC-containing particles. The computational methods that derived from the volume-integral form of the Maxwell equation, such as discrete dipole approximation (DDA), are method of choice for morphologically complex object like BC-containing particles. In ordinary DDA, the entire particle volume is approximated as a collection of tiny cubical dipoles (with side length d) placed on a 3D cubic lattice. For several model BC-containing particles, the comparisons with numerically exact T-matrix method reveals that the ordinary DDA suffered from persistent positive systematic error (up to +30%) in absorption even under d DDA error is identified to be the shape error in BC-spherules. To eliminate the shape error in BC-spherules, we propose a new DDA methodology which may be called hybrid DDA (h-DDA): each primary BC sphere is assumed as a spherical dipole, while remaining particle volume of coating material is approximated by a collection of tiny cubical dipoles on a 3D cubic lattice. Positive absorption bias up to +30% in ordinary DDA is suppressed to within 3% in h-DDA. In h-DDA code, an efficient FFT-based algorithm for solving the matrix equation has been implemented, by utilizing the multilevel block-Toeplitz property of the submatrix corresponding to inter-dipole interaction within coating material.

  11. Nano-twin mediated plasticity in carbon-containing FeNiCoCrMn high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996 (United States); Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2015-10-25

    Equiatomic FeNiCoCrMn alloy has been reported to exhibit promising strength and ductility at cryogenic temperature and deformation mediated by nano-twining appeared to be one of the main reasons. We use the FeNiCoCrMn alloy as a base alloy to seek further improvement of its mechanical properties by alloying additional elements, i.e., interstitial carbon. The effects of carbon on microstructures, mechanical properties and twinning activities were investigated in two different temperatures (77 and 293 K). With addition of 0.5 at% C, the high entropy alloy still remains entirely single phase face-centered cubic (FCC) crystal structure. The materials can be cold rolled and recrystallized to produce a microstructure with equiaxed grains. Both strain hardening rate and strength are enhanced while high uniform elongations to fracture (∼70% at 77 K and ∼40% at 293 K) are still maintained. The increased strain hardening and strength could be caused by the promptness of deformation twinning in C-containing high entropy alloys. - Highlights: • Interstitial atom C was successfully added into FeNiCoCrMn high entropy alloys. • The strain hardening rate and strength are enhanced in the C-containing alloy. • The increased strain-hardening and strength are caused by the nano-twinning.

  12. Discrete dipole approximation for black carbon-containing aerosols in arbitrary mixing state: A hybrid discretization scheme

    Science.gov (United States)

    Moteki, Nobuhiro

    2016-07-01

    An accurate and efficient simulation of light scattering by an atmospheric black carbon (BC)-containing aerosol-a fractal-like cluster of hundreds of carbon monomers that is internally mixed with other aerosol compounds such as sulfates, organics, and water-remains challenging owing to the enormous diversities of such aerosols' size, shape, and mixing state. Although the discrete dipole approximation (DDA) is theoretically an exact numerical method that is applicable to arbitrary non-spherical inhomogeneous targets, in practice, it suffers from severe granularity-induced error and degradation of computational efficiency for such extremely complex targets. To solve this drawback, we propose herein a hybrid DDA method designed for arbitrary BC-containing aerosols: the monomer-dipole assumption is applied to a cluster of carbon monomers, whereas the efficient cubic-lattice discretization is applied to the remaining particle volume consisting of other materials. The hybrid DDA is free from the error induced by the surface granularity of carbon monomers that occurs in conventional cubic-lattice DDA. In the hybrid DDA, we successfully mitigate the artifact of neglecting the higher-order multipoles in the monomer-dipole assumption by incorporating the magnetic dipole in addition to the electric dipole into our DDA formulations. Our numerical experiments show that the hybrid DDA method is an efficient light-scattering solver for BC-containing aerosols in arbitrary mixing states. The hybrid DDA could be also useful for a cluster of metallic nanospheres associated with other dielectric materials.

  13. Gradient Calculation Methods on Arbitrary Polyhedral Unstructured Meshes for Cell-Centered CFD Solvers

    Science.gov (United States)

    Sozer, Emre; Brehm, Christoph; Kiris, Cetin C.

    2014-01-01

    A survey of gradient reconstruction methods for cell-centered data on unstructured meshes is conducted within the scope of accuracy assessment. Formal order of accuracy, as well as error magnitudes for each of the studied methods, are evaluated on a complex mesh of various cell types through consecutive local scaling of an analytical test function. The tests highlighted several gradient operator choices that can consistently achieve 1st order accuracy regardless of cell type and shape. The tests further offered error comparisons for given cell types, leading to the observation that the "ideal" gradient operator choice is not universal. Practical implications of the results are explored via CFD solutions of a 2D inviscid standing vortex, portraying the discretization error properties. A relatively naive, yet largely unexplored, approach of local curvilinear stencil transformation exhibited surprisingly favorable properties

  14. Il doppio ritratto del poliedrico Luca Pacioli. (The double portrait of the polyhedral Luca Pacioli).

    OpenAIRE

    Ciocci, Argante

    2011-01-01

    En este artículo se pasa revista a las investigaciones efectuadas en relación con el autor del famoso cuadro de Luca Pacioli, conservado en el Museo de Capodimonte de Nápoles. Su identidad no está claramente determinada, como tampoco lo está la del personaje que aparece a la izquierda de Pacioli, que generalmente es considerado como el joven duque Guidobaldo de Montefeltro. Su personalidad es también objeto de estudio en el trabajo. Con este motivo, se examinan con extraordinario detalle todo...

  15. R Implementation of a Polyhedral Approximation to a 3D Set of Points Using the ?-Shape

    Directory of Open Access Journals (Sweden)

    Thomas Lafarge

    2014-01-01

    Full Text Available This work presents the implementation in R of the ?-shape of a finite set of points in the three-dimensional space R3. This geometric structure generalizes the convex hull and allows to recover the shape of non-convex and even non-connected sets in 3D, given a ran- dom sample of points taken into it. Besides the computation of the ?-shape, the R package alphashape3d provides users with tools to facilitate the three-dimensional graphical visu- alization of the estimated set as well as the computation of important characteristics such as the connected components or the volume, among others.

  16. Local analysis of hybrid systems on polyhedral sets with state-dependent switching

    Directory of Open Access Journals (Sweden)

    Leth John

    2014-06-01

    Full Text Available This paper deals with stability analysis of hybrid systems. Various stability concepts related to hybrid systems are introduced. The paper advocates a local analysis. It involves the equivalence relation generated by reset maps of a hybrid system. To establish a tangible method for stability analysis, we introduce the notion of a chart, which locally reduces the complexity of the hybrid system. In a chart, a hybrid system is particularly simple and can be analyzed with the use of methods borrowed from the theory of differential inclusions. Thus, the main contribution of this paper is to show how stability of a hybrid system can be reduced to a specialization of the well established stability theory of differential inclusions. A number of examples illustrate the concepts introduced in the paper.

  17. Understanding the physico-chemical properties of polyhedral oligomeric silsesquioxanes: a variable temperature multidisciplinary study.

    Science.gov (United States)

    Croce, Gianluca; Carniato, Fabio; Milanesio, Marco; Boccaleri, Enrico; Paul, Geo; van Beek, Wouter; Marchese, Leonardo

    2009-11-21

    This work is focused on a multidisciplinary study of a completely condensed octaisobutyl-silsesquioxane (IBUPOSS) as a model of the alkyl POSS family. IBUPOSS is characterized by the presence of eight isobutyl groups bonded to the corners of the siliceous framework. Differential scanning calorimetric measurements and an innovative simultaneous in situ Raman/XRPD experiment suggested that IBUPOSS undergoes a solid phase transition around 330 K, and indicated that this transition is related to a change in the conformational freedom of the isobutyl chains. The X-ray powder diffraction (XRPD) pattern of the high temperature phase was indexed in the high symmetry [R3m] space group. The Raman data indicated a larger mobility of the aliphatic side chains at high temperature, thus inducing a disorder in the IBUPOSS moiety. Multidimensional heteronuclear solid-state NMR experiments were employed to probe the structural and motional features of the observed phase transition. The various conformations can be accounted for by a pseudo-D(3h) symmetry able to obey to the [R3m] space group. Simulations on molecular mechanics and dynamics, together with quantum-chemical calculations, confirmed this hypothesis and gave some hints on the conformational mobility and the energetic features of IBUPOSS, a base material with relevant applications in catalysis and polymer science. PMID:19865764

  18. The convex hull of a regular set of integer vectors is polyhedral and effectively computable

    CERN Document Server

    Finkel, Alain; 10.1016/j.ipl.2005.04.004

    2008-01-01

    Number Decision Diagrams (NDD) provide a natural finite symbolic representation for regular set of integer vectors encoded as strings of digit vectors (least or most significant digit first). The convex hull of the set of vectors represented by a NDD is proved to be an effectively computable convex polyhedron.

  19. Epoxy networks reinforced with polyhedral oligomeric silsesquioxanes (POSS). 1. Structure and morphology

    Czech Academy of Sciences Publication Activity Database

    Matějka, Libor; Strachota, Adam; Pleštil, Josef; Whelan, P.; Steinhart, Miloš; Šlouf, Miroslav

    2004-01-01

    Roč. 37, č. 25 (2004), s. 9449-9456. ISSN 0024-9297 R&D Projects: GA AV ČR IAA4050008 Grant ostatní: European Community's Human Potential Programme(XE) HPRN/CT-2002-00306 Institutional research plan: CEZ:AV0Z4050913 Keywords : POSS * epoxy network * structure of nanocomposites Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.898, year: 2004

  20. Construction of scalar and vector finite element families on polygonal and polyhedral meshes

    OpenAIRE

    Gillette, Andrew; Rand, Alexander; Bajaj, Chandrajit

    2014-01-01

    We combine theoretical results from polytope domain meshing, generalized barycentric coordinates, and finite element exterior calculus to construct scalar- and vector-valued basis functions for conforming finite element methods on generic convex polytope meshes in dimensions 2 and 3. Our construction recovers well-known bases for the lowest order N\\'ed\\'elec, Raviart-Thomas, and Brezzi-Douglas-Marini elements on simplicial meshes and generalizes the notion of Whitney forms to non-simplicial c...

  1. R Implementation of a Polyhedral Approximation to a 3D Set of Points Using the ?-Shape

    OpenAIRE

    Thomas Lafarge; Beatriz Pateiro-López; Antonio Possolo; Joy Dunkers

    2014-01-01

    This work has been partially supported by Spanish Grant MTM2008-03010 and the IAP research network grant no. P6/03 from the Belgian government (Beatriz Pateiro-L opez), and by the Shape Metrology Innovations in Measurement Science from the National Institute of Standards and Technology (all the authors). Since the work is a work product of the National Institute of Standards and Technology, an agency of the U.S. federal government, it is not subject to copyright in the United States. We...

  2. Electrical conductivity of sulfonated poly(ether ether ketone) based composite membranes containing sulfonated polyhedral oligosilsesquioxane

    Science.gov (United States)

    Celso, Fabricio; Mikhailenko, Serguei D.; Rodrigues, Marco A. S.; Mauler, Raquel S.; Kaliaguine, Serge

    2016-02-01

    Composite proton exchange membranes (PEMs) intended for fuel cell applications were prepared by embedding of various amounts of dispersed tri-sulfonic acid ethyl POSS (S-Et-POSS) and tri-sulfonic acid butyl POSS (S-Bu-POSS) in thin films of sulfonated poly ether-ether ketone. The electrical properties of the PEMs were studied by Impedance spectroscopy and it was found that their conductivity σ changes with the filler content following a curve with a maximum. The water uptake of these PEMs showed the same dependence. The investigation of initial isolated S-POSS substances revealed the properties of typical electrolytes, which however in both cases possessed low conductivities of 1. 17 × 10-5 S cm-1 (S-Et-POSS) and 3.52 × 10-5 S cm-1 (S-Bu-POSS). At the same time, the insoluble in water S-POSS was found forming highly conductive interface layer when wetted with liquid water and hence producing a strong positive impact on the conductivity of the composite PEM. Electrical properties of the composites were analysed within the frameworks of effective medium theory and bounding models, allowing to evaluate analytically the range of possible conductivity values. It was found that these approaches produced quite good approximation of the experimental data and constituted a fair basis for interpretation of the observed relationship.

  3. Stable ligand-free stellated polyhedral gold nanoparticles for sensitive plasmonic detection

    Science.gov (United States)

    Keunen, Rachel; Macoretta, Danielle; Cathcart, Nicole; Kitaev, Vladimir

    2016-01-01

    Ligand-free stellated gold nanoparticles (AuStNPs) with well-defined octahedral (Oh) and icosahedral (Ih) core symmetries were prepared using hydrogen peroxide as a reducing agent. Only three reagents: gold precursor (HAuCl4), H2O2 and NaOH were required to form colloidally and chemically stable AuStNPs with a zeta-potential between -55 and -40 mV indicative of excellent charge stabilization. The size and degree of stellation of AuStNPs can be controlled by several synthetic parameters so that the localized surface plasmon resonance (LSPR) can be varied from ca. 850 nm in near-infrared (NIR) to ca. 530 nm. In particular, AuStNP size and LSPR tuning can be conveniently accomplished by iodide variation. The size distribution of AuStNPs was improved by nucleation with ascorbic acid, and the AuStNP size and degree of branching could be readily modified using arginine. AuStNPs are advantageous for SPR sensing, as it was demonstrated in the sensitive detection of not only thiols, such as ampicillin, but also iodide with the detection limit of 3.2 pM (0.4 ng L-1). The reported ligand-free stable AuStNPs thus should be very useful for biodiagnostics based on SPR sensing and potentially for SERS and hyperthermia therapy.Ligand-free stellated gold nanoparticles (AuStNPs) with well-defined octahedral (Oh) and icosahedral (Ih) core symmetries were prepared using hydrogen peroxide as a reducing agent. Only three reagents: gold precursor (HAuCl4), H2O2 and NaOH were required to form colloidally and chemically stable AuStNPs with a zeta-potential between -55 and -40 mV indicative of excellent charge stabilization. The size and degree of stellation of AuStNPs can be controlled by several synthetic parameters so that the localized surface plasmon resonance (LSPR) can be varied from ca. 850 nm in near-infrared (NIR) to ca. 530 nm. In particular, AuStNP size and LSPR tuning can be conveniently accomplished by iodide variation. The size distribution of AuStNPs was improved by nucleation with ascorbic acid, and the AuStNP size and degree of branching could be readily modified using arginine. AuStNPs are advantageous for SPR sensing, as it was demonstrated in the sensitive detection of not only thiols, such as ampicillin, but also iodide with the detection limit of 3.2 pM (0.4 ng L-1). The reported ligand-free stable AuStNPs thus should be very useful for biodiagnostics based on SPR sensing and potentially for SERS and hyperthermia therapy. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08788k

  4. Inorganic polyhedral metallacarborane inhibitors of HIV protease: a new approach to overcoming antiviral resistance

    Czech Academy of Sciences Publication Activity Database

    Kožíšek, Milan; Cígler, Petr; Lepšík, Martin; Fanfrlík, Jindřich; Řezáčová, Pavlína; Brynda, Jiří; Pokorná, Jana; Plešek, Jaromír; Grüner, Bohumír; Grantz Šašková, Klára; Prejdová, Jana; Král, V.; Konvalinka, Jan

    2008-01-01

    Roč. 51, č. 15 (2008), s. 4839-4843. ISSN 0022-2623 R&D Projects: GA MŠk 1M0508; GA MŠk LC512; GA MŠk LC523; GA MZd NR8571 EU Projects: European Commission(XE) 37693 - HIV PI RESISTANCE Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50520514; CEZ:AV0Z40320502 Keywords : HIV protease inhibitors * aspartic proteases * viral resistance * metallacarboranes Subject RIV: CE - Biochemistry Impact factor: 4.898, year: 2008

  5. Convex polyhedral abstractions, specialisation and property-based predicate splitting in Horn clause verification

    DEFF Research Database (Denmark)

    Kafle, Bishoksan; Gallagher, John Patrick

    We present an approach to constrained Horn clause (CHC) verification combining three techniques: abstract interpretation over a domain of convex polyhedra, specialisation of the constraints in CHCs using abstract interpretation of query-answer transformed clauses, and refinement by splitting pred...

  6. Coating stent materials with polyhedral oligomeric silsesquioxane-poly(carbonateurea)urethane nanocomposites

    OpenAIRE

    Bakhshi, R.

    2009-01-01

    The long-term efficacy of coronary or peripheral stenting is limited by in-stent restenosis (ISR), which occurs in 15 to 30% of patients and is attributed primarily to neointimal hyperplasia. By adding a drug-eluting coating, this rate has been reduced to about 5% or less. However, recently longer-term follow-up data has highlighted problems with drug-coated stents, including late stage thrombosis. A bio-stable poly(carbonate-urea)urethane has been used for stent coating and th...

  7. Control of the smoldering front temperature in a carbon- and carbonate-containing porous medium in order to limit CO2 emissions

    OpenAIRE

    SENNOUNE, Mohamed

    2011-01-01

    La thèse s’intéresse au contrôle de la température d’un front de combustion propagé dans un milieu poreux contenant du carbone fixe et des carbonates (CaCO3). L’objectif principal est de réduire la température, in situ (récupération d’huile ou production de gaz à partir d’un schiste bitumineux) ou dans un procédé (combustion de semicoke), afin de limiter la décarbonatation du milieu et les émissions induites de CO2. Le milieu réactif retenu pour réaliser les expériences en laboratoire est un ...

  8. The effect of electrochemical phenomena on the deposition of carbon containing inorganic thin films from supersonic expansion of aqueous supercritical solutions

    Science.gov (United States)

    Sezer, Ali Osman

    The supersonic expansion of dilute aqueous solutions for the synthesis of new materials is a complex flow system. Flow prediction and modeling are, therefore, quite challenging. Electrokinetic streaming potentials generated during the supersonic nozzle expansion further complicate the nature of these flow processes. Flow-generated potentials are believed to significantly affect the electrochemical environment of the flow, and therefore, may influence the properties of the product. This dissertation research was an attempt to experimentally and theoretically investigate the significance of flow-generated electrochemical phenomena and their possible effect on the deposited thin carbon films. Brand's computer model was used to predict the physical properties of the expanding jet at the nozzle. The sensitivity of the predicted flow parameters to operating conditions was then analyzed. The results of this parametric flow modeling were used to identify deposition regions of flow space that have less sensitivity to fluctuations in process temperatures and pressures. Streaming currents were predicted from measured nozzle currents. The first high-temperature-pressure Pourbaix diagrams were constructed for the carbon-water system. Equilibrium Pourbaix diagrams together with predicted streaming currents suggested a possible CVD-like mechanism for the deposition of thin carbon films. Deposited carbon films were analyzed for morphology, composition and structure by vibrational spectroscopy and electron microscopy. IR and Raman analysis of carbon samples were not conclusive in revealing any measurable differences in samples. Although Raman spectra showed considerable shifts in peak positions, the lack of internal standard in the spectra made it difficult to draw any reliable conclusions. Significant variations in surface morphology were found for samples grown under different substrate bias. Electron diffraction analysis conclusively showed the presence of a cubic diamond and Lonsdaleite phase in a carbon sample, which supports the predicted CVD-like deposition mechanism in the process that enables the phase transition from hexagonal graphite to cubic diamond.

  9. Real-time and single-particle volatility of elemental carbon-containing particles in the urban area of Pearl River Delta region, China

    Science.gov (United States)

    Bi, Xinhui; Dai, Shouhui; Zhang, Guohua; Qiu, Ning; Li, Mei; Wang, Xinming; Chen, Duohong; Peng, Ping'an; Sheng, Guoying; Fu, Jiamo; Zhou, Zhen

    2015-10-01

    Elemental carbon (EC) aerosol represents an important fraction of aerosol particles in urban area of the Pearl River Delta (PRD) region, China. Previous studies have demonstrated that EC particles in the PRD region undergo significant amounts of aging processes. To assess the degree of aging, the real-time single particle volatility of EC-containing particles was measured in an urban area of the PRD region by a thermodiluter coupled to a single particle aerosol mass spectrometer (SPAMS). The size and chemical composition of the individual particles before and after heating to 75 °C, 150 °C and 300 °C were characterized. Of the total unheated particles examined by SPAMS, 53% of the unheated particles contained EC, and a higher number fraction (69%) was observed in the particles heated to 300 °C. No significant differences in the mass spectral patterns were found between ambient temperature and 75 °C. Nitrate evaporated at 150 °C, and most of sulfate evaporated at 300 °C. EC-containing particles were clustered into four distinct particle types based on the dominant chemical species present in the mass spectra, comprised of EC, internally mixed EC and organic carbon (OC) (ECOC), internally mixed EC and sodium/potassium salt (NaK-EC), and internally mixed EC and metal species (Metal-EC). Detail analysis show that the volatility of EC-containing particles relied on the EC particle types. Among the four types, the EC type was quite volatile. A significant fraction of sulfate and organics in the ECOC type did not volatilize at 300 °C. The volatilities of secondary ions in the four EC-containing particle types were found to be dependent on their molecular composition. Additionally, the volatility of EC-containing particles decreased during the polluted hazy days due to the generation of low volatile compounds under the atmospheric conditions with higher precursor concentrations and oxidation capacity. To our knowledge, this is the first reported real-time volatility measurements of individual ambient aerosols in the PRD region. These findings provide an improved understanding of the aging process of EC particles, and may help in the modeling of its climate impact.

  10. Melt-texturing of carbon containing YBa2Cu3O7-x: Influence of processing parameters on microstructure and flux-pinning behavior

    International Nuclear Information System (INIS)

    A detailed study of the flux-pinning behavior of sintered and melt-textured YBa2Cu3O7-x has been carried out by means of microstructural investigations (optical microscopy, SEM, TEM, EDS, DTA, and XRD) and magnetization measurements. It was found that both microstructure and magnetization behavior strongly depend on the starting material, the production method, and the maximum processing temperature. In our experiments, the critical current density, Jc, increased with increasing processing temperature between 920 degrees C and 1050 degrees C (25 - 130 emu/cm3), but those samples processed at temperatures just above the peritectic transformation point (1020 OC and 1030 OC) exhibited a decreased Jc. The carbon content of the starting powder and the powder's melting behavior seem to play an important role in the development of microstructure and flux-pinning behavior during melt-texturing. A comparison of our data with previously published results shows that an optimized melt-texturing process can result in materials with critical current densities comparable to those of samples produced by Quench-Melt Growth

  11. Kinetic study of the reaction of uranium with various carbon-containing gases; Etude cinetique de la reaction sur l'uranium de differents gaz carbones

    Energy Technology Data Exchange (ETDEWEB)

    Feron, G. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-09-15

    The kinetic study of the reaction U + CO{sub 2} and U + CO has been performed by a thermogravimetric method on a spherical uranium powder, in temperature ranges respectively from 460 to 690 deg. C and from 570 to 850 deg. C. The reaction with carbon dioxide leads to uranium dioxide. A carbon deposition takes place at the same time. The global reactions is the result of two reactions: U + 2 CO{sub 2} {yields} UO{sub 2} + 2 CO U + CO{sub 2} {yields} UO{sub 2} + C The reaction with carbon monoxide leads to a mixture of dioxide UO{sub 2}, dicarbide UC{sub 2} and free carbon. The main reaction can be written. U + CO {yields} 1/2 UO{sub 2} + 1/2 UC{sub 2} The free carbon results of the disproportionation of the carbon monoxide. A remarkable separation of the two phases UO{sub 2} and UC{sub 2} can be observed. A mechanism accounting for the phenomenon has been proposed. The two reactions U + CO{sub 2} and U + CO begin with a long germination period, after which, the reaction velocity seems to be limited in both cases by the ionic diffusion of oxygen through the uranium dioxide. (author) [French] L'etude cinetique des reactions U sol + CO{sub 2} gaz et U sol + CO gaz a ete effectuee par thermogravirnetrie sur une poudre d'uranium a grains spheriques, les domaines de temperature etudies s'etendant respectivement de 460 a 690 deg. C et de 570 a 850 deg. C. L'action du dioxyde de carbone conduit au dioxyde d'uranium UO{sub 2}; il se produit en meme temps un depot de carbone. La reaction globale resulte des deux reactions: U + 2 CO{sub 2} {yields} UO{sub 2} + 2 CO U + CO{sub 2} {yields} UO{sub 2} + C Le mono-oxyde de carbone conduit a un melange de dioxyde UO{sub 2}, de dicarbure UC{sub 2} et de carbone libre. La reaction principale s'ecrit: U + CO {yields} 1/2 UO{sub 2} + 1/2 UC{sub 2} Le carbone libre provient de la dismutation du mono-oxyde de carbone. On observe une separation remarquable des deux phases UO{sub 2} et UC{sub 2}; un mecanisme rendant compte de ce phenomene a ete propose. Les deux reactions U + CO{sub 2} et U + CO, debutent par une longue periode de germination, apres laquelle la vitesse de la reaction semble etre limitee dans les deux cas par la diffusion d'ions O{sup 2-} dans l'oxyde UO{sub 2} forme. (auteur)

  12. Behaviour of highly crystalline graphitic materials in lithium-ion cells with propylene carbonate containing electrolytes: An in situ Raman and SEM study

    International Nuclear Information System (INIS)

    The microcrystalline flaked graphites SFG6 and SFG44 were evaluated with regard to their compatibility with propylene carbonate (PC) by in situ Raman microscopy and postmortem scanning electron microscopy (SEM) study. PC is employed as electrolyte component in lithium-ion batteries. However, when used with certain types of graphitic materials, exfoliation occurs. To compare the effects of exfoliation, the first lithium insertion properties of these graphitic materials were measured with in situ Raman microscopy. Lithium half-cells containing either 1 M LiClO4 1:1 (w/w) ethylene carbonate (EC):dimethyl carbonate (DMC) or 1:1 (w/w) EC:PC were investigated. The commencement of the exfoliation process was detected in SFG44 EC:PC by the appearance of a shoulder band at 1597 cm-1 on the G-band (1584 cm-1) below 0.9 V versus Li/Li+. The band (assigned as the exfoliation or E-band) at higher wavenumbers (1597 cm-1) corresponded to solvated lithium ions intercalated into graphite. The in situ Raman spectra of SFG6 in EC:DMC or EC:PC and SFG44 in EC:DMC did not show the E-band and instead displayed regular lithium intercalation spectra. In situ Raman microscopy and SEM were further employed to study the exfoliation process observed for SFG44 in 1:1 (w/w) EC:PC, when the potential was held under steady-state conditions at 0.8, 0.6 and 0.3 V, respectively. A blue-shift in the E-band from 1597 to 1607 cm-1 was observed as the potential was lowered. SEM images showed dissimilar degrees of exfoliation at these three potentials

  13. Magnetron sputter deposition of low-stress, carbon-containing cubic boron nitride films using Ar-N2-CH4 gas mixtures

    International Nuclear Information System (INIS)

    Cubic boron nitride (c-BN) films produced by PVD and plasma-assisted CVD techniques typically exhibit undesired high compressive stresses. One of the effective and feasible methods to reduce stress and hence improve film adhesion has been a controlled addition of a third element into the film during deposition. In the present study, BN films were grown on to silicon substrates using reactive magnetron sputtering with a hexagonal BN target. An auxiliary flow of methane was mixed into argon and nitrogen as the working gas. The deposition was conducted at various methane flow rates at 400 oC substrate temperature, 0.2 Pa total working pressure, and - 250 V r.f. substrate bias. The microstructure of the deposited films was then examined in dependence of the methane flow rate. With increasing methane flow rate from 0 to approx. 2.0 sccm, the fraction of the cubic BN phase in the deposited films decreased gradually down to approx. 75 vol.%, whereas the film stress was reduced much more rapidly and almost linearly in relation to the methane flow rate. At 2.1 sccm methane, the stress became approx. 3 times reduced. Owing to the significantly decreased film stress, adherent, micrometer thick, cubic-phase dominant films can be allowed to form on silicon substrate. The microstructure of the films will be illustrated through FTIR and XRR.

  14. Development of a new type of SiGe thin strain relaxed buffer based on the incorporation of a carbon-containing layer

    International Nuclear Information System (INIS)

    We describe a new technique for the fabrication of a thin strain relaxed buffer (TSRB). This method is based on the incorporation of carbon during the epitaxial growth of a thin constant composition Si0.78Ge0.22 layer. An annealing step is carried out after growth in order to increase the relaxation and therefore the stability of the buffer. This method allows to prepare smooth and defect free TSRBs with 91% relaxation. First Hall mobility measurements at 77 K of strained silicon on top of the TSRB (single side modulation doped structure) show promising electron mobility value of 18,500 cm2/(V s)

  15. A rare cationic building block that generates a new type of polyhedral network with "cross-linked" pto topology.

    Science.gov (United States)

    Lusi, Matteo; Fechine, Pierre B A; Chen, Kai-Jie; Perry, John J; Zaworotko, Michael J

    2016-03-01

    A rare 8-connected cationic building block, [Cu2L8(μ-MF6)](2+) (L = pyridyl ligand, M = Si, Ti, Ge, Zr or Sn), enables the formation of a small cubicuboctahedral supramolecular building block, SBB, when complexed by 2,4,6-tris(4-pyridyl)pyridine. The coordination network resulting from fusing the square faces of the SBBs can be described as a pto topology in which half of the square faces are cross-linked by MF6(2-) moieties, and represents the first example of a new 3,5-c topology. PMID:26902412

  16. Superhydrophobic-superhydrophilic binary micropatterns by localized thermal treatment of polyhedral oligomeric silsesquioxane (POSS)-silica films.

    Science.gov (United States)

    Schutzius, Thomas M; Bayer, Ilker S; Jursich, Gregory M; Das, Arindam; Megaridis, Constantine M

    2012-09-01

    Surfaces patterned with alternating (binary) superhydrophobic-superhydrophilic regions can be found naturally, offering a bio-inspired template for efficient fluid collection and management technologies. We describe a simple wet-processing, thermal treatment method to produce such patterns, starting with inherently superhydrophobic polysilsesquioxane-silica composite coatings prepared by spray casting nanoparticle dispersions. Such coatings become superhydrophilic after localized thermal treatment by means of laser irradiation or open-air flame exposure. When laser processed, the films are patternable down to ∼100 μm scales. The dispersions consist of hydrophobic fumed silica (HFS) and methylsilsesquioxane resin, which are dispersed in isopropanol and deposited onto various substrates (glass, quartz, aluminum, copper, and stainless steel). The coatings are characterized by advancing, receding, and sessile contact angle measurements before and after thermal treatment to delineate the effects of HFS filler concentration and thermal treatment on coating wettability. SEM, XPS and TGA measurements reveal the effects of thermal treatment on surface chemistry and texture. The thermally induced wettability shift from superhydrophobic to superhydrophilic is interpreted with the Cassie-Baxter wetting theory. Several micropatterned wettability surfaces demonstrate potential in pool boiling heat transfer enhancement, capillarity-driven liquid transport in open surface-tension-confined channels (e.g., lab-on-a-chip), and select surface coating applications relying on wettability gradients. Advantages of the present approach include the inherent stability and inertness of the organosilane-based coatings, which can be applied on many types of surfaces (glass, metals, etc.) with ease. The present method is also scalable to large areas, thus being attractive for industrial coating applications. PMID:22820974

  17. Enhanced processability of MWCNT through surface treatment by octa(phenol) polyhedral oligomeric silsesquioxane nano-crosslinking

    Science.gov (United States)

    Omrani, Abdollah; Yen, Ying-Chieh; Cheng, Chih-Chia; Chang, Feng-Chih

    2014-01-01

    A facile method was developed to prepare MWCNT/POSS nanocomposites by direct esterification between carboxylic acid functionalized MWCNT and octa(phenol) octasilsesquioxane. Completeness of the MWCNT surface modification was confirmed by FT-IR. The hybrid nano-MWCNT-OP-POSS composite structure and properties was characterized using DSC, TGA, optical microscopy, WAXD, and AFM. The results indicated the solubility and processability of MWCNT-COOH improved because of OP-POSS grafting on MWCNT surface. The Tg and thermal stability of the nanocomposites was higher than that of the OP-POSS as a result of the cross-linking reaction. AFM observations revealed that the nanocomponents were reacted in a homogeneous phase at nanoscale level.

  18. Gold Nanoparticle@Polyhedral Oligomeric Silsesquioxane Hybrid Scaffolds in Microfluidic Format – Highly Efficient and Green Catalytic Platforms

    Science.gov (United States)

    Scholder, Pascal; Hafner, Martina; Hassel, Achim W.; Nischang, Ivo

    2016-01-01

    Abstract We report on the preparation of new hybrid organic–inorganic multiporous monolithic capillary columns carrying gold nanoparticles of 5, 10, 50, and 100 nm size and their use as flow‐through catalytic platforms for aqueous liquid‐phase reduction reactions. We found that the flow‐through performance of the reactors depends not only on the size of the gold nanoparticles but also on the interplay of the pore size of the scaffolds and the catalytically available gold surface within the system, that is, loading an increased number of gold nanoparticles of smaller size does not necessarily result in strictly improved performance. This indicates the importance of the interplay between the nanopore size of the scaffolds and the catalytically active gold surface existing within the system. Demonstration of the highly efficient catalytic flow‐through operation within seconds and the repeated use of the reactors without loss of performance indicates their excellent suitability as microfluidic device elements.

  19. Superhydrophobic-superhydrophilic binary micropatterns by localized thermal treatment of polyhedral oligomeric silsesquioxane (POSS)-silica films

    Science.gov (United States)

    Schutzius, Thomas M.; Bayer, Ilker S.; Jursich, Gregory M.; Das, Arindam; Megaridis, Constantine M.

    2012-08-01

    Surfaces patterned with alternating (binary) superhydrophobic-superhydrophilic regions can be found naturally, offering a bio-inspired template for efficient fluid collection and management technologies. We describe a simple wet-processing, thermal treatment method to produce such patterns, starting with inherently superhydrophobic polysilsesquioxane-silica composite coatings prepared by spray casting nanoparticle dispersions. Such coatings become superhydrophilic after localized thermal treatment by means of laser irradiation or open-air flame exposure. When laser processed, the films are patternable down to ~100 μm scales. The dispersions consist of hydrophobic fumed silica (HFS) and methylsilsesquioxane resin, which are dispersed in isopropanol and deposited onto various substrates (glass, quartz, aluminum, copper, and stainless steel). The coatings are characterized by advancing, receding, and sessile contact angle measurements before and after thermal treatment to delineate the effects of HFS filler concentration and thermal treatment on coating wettability. SEM, XPS and TGA measurements reveal the effects of thermal treatment on surface chemistry and texture. The thermally induced wettability shift from superhydrophobic to superhydrophilic is interpreted with the Cassie-Baxter wetting theory. Several micropatterned wettability surfaces demonstrate potential in pool boiling heat transfer enhancement, capillarity-driven liquid transport in open surface-tension-confined channels (e.g., lab-on-a-chip), and select surface coating applications relying on wettability gradients. Advantages of the present approach include the inherent stability and inertness of the organosilane-based coatings, which can be applied on many types of surfaces (glass, metals, etc.) with ease. The present method is also scalable to large areas, thus being attractive for industrial coating applications.Surfaces patterned with alternating (binary) superhydrophobic-superhydrophilic regions can be found naturally, offering a bio-inspired template for efficient fluid collection and management technologies. We describe a simple wet-processing, thermal treatment method to produce such patterns, starting with inherently superhydrophobic polysilsesquioxane-silica composite coatings prepared by spray casting nanoparticle dispersions. Such coatings become superhydrophilic after localized thermal treatment by means of laser irradiation or open-air flame exposure. When laser processed, the films are patternable down to ~100 μm scales. The dispersions consist of hydrophobic fumed silica (HFS) and methylsilsesquioxane resin, which are dispersed in isopropanol and deposited onto various substrates (glass, quartz, aluminum, copper, and stainless steel). The coatings are characterized by advancing, receding, and sessile contact angle measurements before and after thermal treatment to delineate the effects of HFS filler concentration and thermal treatment on coating wettability. SEM, XPS and TGA measurements reveal the effects of thermal treatment on surface chemistry and texture. The thermally induced wettability shift from superhydrophobic to superhydrophilic is interpreted with the Cassie-Baxter wetting theory. Several micropatterned wettability surfaces demonstrate potential in pool boiling heat transfer enhancement, capillarity-driven liquid transport in open surface-tension-confined channels (e.g., lab-on-a-chip), and select surface coating applications relying on wettability gradients. Advantages of the present approach include the inherent stability and inertness of the organosilane-based coatings, which can be applied on many types of surfaces (glass, metals, etc.) with ease. The present method is also scalable to large areas, thus being attractive for industrial coating applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30979c

  20. Thermal and mechanical properties of hydroxyl-terminated polybutadiene-based polyurethane/polyhedral oligomeric silsesquioxane nanocomposites plasticized with DOA.

    Science.gov (United States)

    Kim, Ho-Joong; Kwon, Younghwan; Kim, Chang Kee

    2013-01-01

    Thermal and mechanical properties of PU/POSS nanocomposites plasticized with DOA were investigated. These hybrid materials were prepared using one-step method through the incorporation of flexible HTPB prepolymer, reactive or non-reactive POSS nanoparticle, and DOA plasticizer under IPDI curative system. The plasticizer added into PU/POSS composites decreased glass transition temperature, mechanical strength and modulus, while the change of thermal stability was modest. Thermal stability of these hybrid composites was found to depend preferably on characteristics of POSS molecules incorporated. PMID:23646777

  1. Procedimiento de corte en cuerpos sólidos poliédricos // Section procedure in solid polyhedral bodies.

    OpenAIRE

    A. Miguel Iznaga Benítez; I. Pérez Mallea

    2000-01-01

    El conocimiento de la estructura de datos de los modelos geométricos ha posibilitado el desarrollo de algoritmos parasolucionar problemas complejos. Estos algoritmos han facilitado a su vez, la automatización en las oficinas de diseño através de los medios computacionales.Por tal motivo, se presenta el desarrollo de un algoritmo para la obtención de cortes y secciones en cuerpos geométricospoliédricos, se plantean las etapas fundamentales del algoritmo y a través de un ejercicio se ejemplific...

  2. Accessibility studies of ionic and non-ionic fluorophores embedded in sol-gel materials and new functionalised polyhedral silsesquioxanes

    OpenAIRE

    Ruiz Abad, David

    2009-01-01

    The knowledge about the diffusion of products and educts into and out of porous materials is of high importance for the development of new porous sol-gel processed hybrid catalysts. Therefore the accessibility of active centers embedded in sol-gel materials was studied by luminescence spectroscopy. Modified tris(2,2’- bipyridine)ruthenium(II) and pyrenemethanol were co-condensed with tetramethoxysilane (TMOS) in a buffer system. The buffer enforces the pH to remain constant during the sol-gel...

  3. Polyhedral Units and Network Connectivity in Calcium Aluminosilicate Glasses from High-Energy X-Ray Diffraction

    International Nuclear Information System (INIS)

    Structure factors for Cax/2Al xSi1-xO2 glasses (x=0,0.25,0.5,0.67) extended to a wave vector of magnitude Q=40 Angstroem-1 have been obtained by high-energy x-ray diffraction. For the first time, it is possible to resolve the contributions of Si-O, Al-O, and Ca-O coordination polyhedra to the experimental atomic pair distribution functions. It has been found that the connectivity of Si/Al-O tetrahedral network decreases with increasing x due to the emerging of nonbridging oxygens located on Si-O tetrahedra. Calcium maintains a rather uniform coordination sphere for all values of x and so it plays a certain role in determining the glass structure

  4. Effect of borates on thermal degradation and flame retardancy of epoxy resins using polyhedral oligomeric silsesquioxane as a curing agent

    International Nuclear Information System (INIS)

    Highlights: ► Flame retarded epoxy resins with borates were prepared using POSS as a curing agent. ► Borates and POSS exhibited a synergistic effect on flame retardancy of epoxy resins. ► Incorporation of borates and POSS significantly reduced the heat release rate. - Abstract: A series of flame-retardant epoxy resins containing boron and silicon were obtained through a crosslinking reaction, using tris (2-hydroxypropyl) borate (THPB) together with octaaminophenyl POSS (OapPOSS) as the curing agents. The limiting oxygen index (LOI) reached 30.5% when the contents of boron and silicon in the cured system were 1.5% and 0.5%, respectively, indicating that THPB and OapPOSS exhibited good flame retardant effect on epoxy resins (EP). Microscale combustion calorimetry (MCC) results indicated that the peak heat release rate (PHRR) and total heat release (THR) of the cured systems were reduced by 69% and 46%, respectively, compared to those of pure EP. Moreover, the thermal degradation process and flame retardant mechanism of the composites were investigated by TGA, real time FTIR and TG-FTIR. The chemical components of the char residues were explored by XPS.

  5. Influence of the polyhedral oligomeric silsesquioxane n-phenylaminopropyl: POSS in the thermal stability and the glass transition temperature of epoxy resin

    Directory of Open Access Journals (Sweden)

    Vinícius Pistor

    2013-01-01

    Full Text Available In this study, epoxy nanocomposites containing different fractions of n-phenylaminopropyl (POSS were prepared. The nanocomposites were studied by transmission electron microscopy (TEM, gel content, dynamic-mechanical analysis (DMA and thermogravimetric analysis (TGA. The parameters for Avrami's equation were calculated from the degradation curves. The dispersions used to form the nanocomposites were effective above 5 wt % of POSS, and the gel content increased with the addition of POSS. The DMA analysis exhibited an increase in the storage modulus (E' and a shifting of Tg to higher temperatures upon POSS incorporation. The weight loss indicated that the POSS promoted an increase in thermal stability of the epoxy resin. The Avrami parameters demonstrated that the addition of POSS decreased the Avrami constant (k', increased the half-life (t1/2 of degradation and promoted changes in the Avrami exponent (n. These results suggest that the increase in the glass transition temperature and thermal stability depend on the reactive groups in the POSS nanoparticles.

  6. Influence of the polyhedral oligomeric silsesquioxane n-phenylaminopropyl: POSS in the thermal stability and the glass transition temperature of epoxy resin

    OpenAIRE

    Vinícius Pistor; Bluma Guenther Soares; Raquel Santos Mauler

    2013-01-01

    In this study, epoxy nanocomposites containing different fractions of n-phenylaminopropyl (POSS) were prepared. The nanocomposites were studied by transmission electron microscopy (TEM), gel content, dynamic-mechanical analysis (DMA) and thermogravimetric analysis (TGA). The parameters for Avrami's equation were calculated from the degradation curves. The dispersions used to form the nanocomposites were effective above 5 wt % of POSS, and the gel content increased with the addition of POSS. T...

  7. Theoretical insight into the structural stability of KZnB3O6 polymorphs with different BO(x) polyhedral networks.

    Science.gov (United States)

    Yang, Lei; Fan, Weiliu; Li, Yanlu; Sun, Honggang; Wei, Lei; Cheng, Xiufeng; Zhao, Xian

    2012-06-18

    In general, the presence of shared edges of polyhedra for high-valence low-coordinated small cations is rarely seen except under extreme conditions such as high pressure. However, the ambient-pressure synthesis of KZnB(3)O(6) built of edge-sharing BO(4) tetrahedra is contrary to this. By investigating the molecular dynamics, lattice dynamics, and electronic properties via density functional theory, we studied the origin of the phase stability of the edge-sharing (es) and "corner-sharing (cs)" KZnB(3)O(6). Lattice dynamics results show that there are no phonon anomalies that could lead to the instability of es-KZnB(3)O(6), which is consistent with molecular dynamics analysis. For "cs-KZnB(3)O(6)", a soft mode at the G point in the phonon dispersion is identified that reflects the dynamic instability with respect to small distortions. Eigenvector analysis of the soft mode of "cs-KZnB(3)O(6)" indicates that the instability comes from the linkage of ZnO(5) polyhedra rather than BO(x) polyhedra. Electronic property calculation indicates that the edge-sharing BO(4) polyhedra connected by the longest B-O σ bonds provide a solid framework for es-KZnB(3)O(6). In the case of "cs-KZnB(3)O(6)", the overlong Zn-O bond possesses the smallest covalent nature and the least orbital overlap among the bonds in a ZnO(5) polyhedron, and these two features of the electronic structure reduce the stability of "cs-KZnB(3)O(6)" compared to es-KZnB(3)O(6). The electronic property calculation further confirms the results obtained from lattice dynamics analysis. PMID:22667686

  8. Formation of a Metalloporphyrin-Based Nanoreactor by Postsynthetic Metal-Ion Exchange of a Polyhedral-Cage Containing a Metal-Metalloporphyrin Framework

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xi-Sen; Chrzanowski, Matthew; Wojtas, Lukasz; Chen, Yu-Sheng; Ma, Shengqian [USF; (UC)

    2013-03-19

    A change for the better: Exchange of CdII in the catalytically inactive framework MMPF-5 (see scheme) with CoII afforded a metalloporphyrin-based nanoreactor, MMPF-5(Co). This framework, consisting of small cubicuboctahedral cages, demonstrated interesting performances in the catalytic epoxidation of trans-stilbene with tBuOOH.

  9. Formation of a metalloporphyrin-based nanoreactor by postsynthetic metal-ion exchange of a polyhedral-cage containing a metal-metalloporphyrin framework.

    Science.gov (United States)

    Wang, Xi-Sen; Chrzanowski, Matthew; Wojtas, Lukasz; Chen, Yu-Sheng; Ma, Shengqian

    2013-03-01

    A change for the better: Exchange of Cd(II) in the catalytically inactive framework MMPF-5 (see scheme) with Co(II) afforded a metalloporphyrin-based nanoreactor, MMPF-5(Co). This framework, consisting of small cubicuboctahedral cages, demonstrated interesting performances in the catalytic epoxidation of trans-stilbene with tBuOOH. PMID:23386517

  10. Polyhedral Platinaborane Chemistry. Interaction of PMe2Ph with [((PMePh)-Ph-2)(2)PtB10H12

    Czech Academy of Sciences Publication Activity Database

    Bould, Jonathan; Císařová, I.; Kennedy, J.D.

    2012-01-01

    Roč. 31, č. 7 (2012), s. 2691-2696. ISSN 0276-7333 R&D Projects: GA ČR(CZ) GAP207/11/1577; GA ČR(CZ) GAP207/11/0705 Institutional research plan: CEZ:AV0Z40320502 Keywords : NUCLEAR-MAGNETIC-RESONANCE * OXIDATIVE-INSERTION REACTIONS * CLUSTER CHEMISTRY * METALLAHETEROBORANE CHEMISTRY Subject RIV: CA - Inorganic Chemistry Impact factor: 4.145, year: 2012

  11. Melt-texturing of carbon containing YBa{sub 2}Cu{sub 3}O{sub 7-x}: Influence of processing parameters on microstructure and flux-pinning behavior

    Energy Technology Data Exchange (ETDEWEB)

    Todt, V.R. [Argonne National Lab., IL (United States)]|[Technische Hochschule Aachen (Germany); Sengupta, S. [Argonne National Lab., IL (United States)]|[Notre Dame Univ., IN (United States). Dept. of Materials Science and Engineering; Chen, Y.L. [Argonne National Lab., IL (United States)]|[Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science and Engineering; Shi, Donglu; Poeppel, R. [Argonne National Lab., IL (United States)], Sahm, P.R. [Technische Hochschule Aachen (Germany); McGinn, P.J. [Notre Dame Univ., IN (United States). Dept. of Materials Science and Engineering; Chan, H.M.; Harmer, M.P. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science and Engineering

    1994-01-01

    A detailed study of the flux-pinning behavior of sintered and melt-textured YBa{sub 2}Cu{sub 3}O{sub 7-x} has been carried out by means of microstructural investigations (optical microscopy, SEM, TEM, EDS, DTA, and XRD) and magnetization measurements. It was found that both microstructure and magnetization behavior strongly depend on the starting material, the production method, and the maximum processing temperature. In our experiments, the critical current density, J{sub c}, increased with increasing processing temperature between 920{degrees}C and 1050{degrees}C (25 - 130 emu/cm{sup 3}), but those samples processed at temperatures just above the peritectic transformation point (1020 OC and 1030 OC) exhibited a decreased J{sub c}. The carbon content of the starting powder and the powder`s melting behavior seem to play an important role in the development of microstructure and flux-pinning behavior during melt-texturing. A comparison of our data with previously published results shows that an optimized melt-texturing process can result in materials with critical current densities comparable to those of samples produced by Quench-Melt Growth.

  12. Understanding Boron through Size-Selected Clusters: Structure, Chemical Bonding, and Fluxionality

    Energy Technology Data Exchange (ETDEWEB)

    Sergeeva, Alina P.; Popov, Ivan A.; Piazza, Zachary A.; Li, Wei-Li; Romanescu, Constantin; Wang, Lai S.; Boldyrev, Alexander I.

    2014-04-15

    Conspectus Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center–two-electron (2c–2e) σ bonds on the periphery and delocalized multicenter–two-electron (nc–2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron’s electron deficiency and leads to fluxional behavior, which has been observed in B13+ and B19–. A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiation has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B–, formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B

  13. Conjugates of polyhedral boron compounds with carbohydrates. Communication 3. The first synthesis of a conjugate of the dodecaborate anion with a disaccharide lactose as a potential agent for boron neutron capture therapy of cancer

    International Nuclear Information System (INIS)

    An approach is reported which affords conjugates of the dodecaborate anion with practically any oligosaccharide derivative containing amino group. The conjugate was synthesized by condensation of N-glycyl-β-lactosyl amine with dodecaborate carboxy derivative, [B12H11O(CH2)4CO2]3-·3Bu4N+, in (2:1) methanol-water mixture in the presence of DMT-MM as a condensing agent. The product was obtained in 57% yield and characterized by 1H, 13C, 11B{1H} NMR and mass-spectra

  14. Vibrational dynamics of 3D granular media composed with polyhedral grains -- Din\\'amica vibracional de un medio granular 3D compuesto de part\\'iculas poli\\'edricas

    CERN Document Server

    Azema, Émilien; Peyroux, R; Dubois, Frédéric; Saussine, G

    2008-01-01

    By means of tree-dimensional contact dynamics simulations, we analyze the vibrational dynamics of a confined granular layer in response to harmonic forcing. The sample is composed of polyedric grains with a shape derived from digitalized ballast. The system involves a jammed state separating passive (loading) and active (unloading) states. We show that an approximate expression of the packing resistance force as a function of the displacement of the free retaining wall from the jamming position provides a good description of the dynamics. We study in detail the scaling of displacements and velocities with loading parameters. In particular, we find that, for a wide range of frequencies, the data collapse by scaling the displacements with the inverse square of frequency, the inverse of the force amplitude and the square of gravity. We show that the mean compaction rate increases linearly with frequency up to a characteristic frequency of 10 Hz and then it declines in inverse proportion to frequency.

  15. Noncovalent Interactions of Heteroboranes

    Czech Academy of Sciences Publication Activity Database

    Sedlák, Robert; Fanfrlík, Jindřich; Pecina, Adam; Hnyk, Drahomír; Hobza, Pavel; Lepšík, Martin

    Cham: Springer International Publishing, 2015 - (Hnyk, D.; McKee, M.), s. 219-239. (Challenges and Advances in Computational Chemistry and Physics. 20). ISBN 978-3-319-22281-3 Institutional support: RVO:61388963 ; RVO:61388980 Keywords : sigma-hole bonding * boron clusters * quantum chemistry Subject RIV: CF - Physical ; Theoretical Chemistry

  16. Cationic Closo-carboranes 2. Do computed 11B and 13C NMR chemical shifts support their experimental availability?

    Czech Academy of Sciences Publication Activity Database

    Hnyk, Drahomír; Jayasree, E.G.

    2013-01-01

    Roč. 34, č. 8 (2013), s. 656-661. ISSN 0192-8651 R&D Projects: GA ČR GAP208/10/2269 Institutional support: RVO:61388980 Keywords : boron clusters * weakly-coordinating cations * 11B NMR * dynamic electron correlation Subject RIV: CA - Inorganic Chemistry Impact factor: 3.601, year: 2013

  17. Salts of Dodecamethylcarba-closo-dodecaborate(-) Anion, CB11Me12-, and the Radical Dodecamethylcarba-closo-dodecaboranyl, CB11Me12

    Czech Academy of Sciences Publication Activity Database

    Clayton, J. R.; King, B. T.; Zharov, I.; Fete, M. G.; Volkis, V.; Douvris, C.; Valášek, Michal; Michl, Josef

    2010-01-01

    Roč. 35, - (2010), s. 56-63. ISSN 0073-8077 Grant ostatní: NSF(US) CHE0446688; NSF(US) CHE0848477 Institutional research plan: CEZ:AV0Z40550506 Keywords : boron clusters * methylation * stable free radical Subject RIV: CF - Physical ; Theoretical Chemistry

  18. Synthesis, characterisation and some chemistry of C- and B-substituted carboxylic acids of cobalt bis(dicarbollide)

    Czech Academy of Sciences Publication Activity Database

    Nekvinda, Jan; Šícha, Václav; Hnyk, Drahomír; Grüner, Bohumír

    2014-01-01

    Roč. 43, č. 13 (2014), s. 5106-5120. ISSN 1477-9226 R&D Projects: GA AV ČR IAAX00320901 Institutional support: RVO:61388980 Keywords : BORON-CLUSTER COMPOUNDS * EFFICIENT EXTRACTANTS * ACTINIDE EXTRACTIONS Subject RIV: CA - Inorganic Chemistry Impact factor: 4.197, year: 2014

  19. Boron Atoms as Spin Carriers in Two- and Three-Dimensional Systems

    Czech Academy of Sciences Publication Activity Database

    Kaim, W.; Hosmane, N. S.; Záliš, Stanislav; Maguire, J. A.; Lipscomb, W. N.

    2009-01-01

    Roč. 48, č. 28 (2009), s. 5082-5091. ISSN 1433-7851 R&D Projects: GA MŠk OC 139; GA AV ČR KAN100400702 Institutional research plan: CEZ:AV0Z40400503 Keywords : boron * cluster compounds * organoboranes * radicals Subject RIV: CG - Electrochemistry Impact factor: 11.829, year: 2009

  20. Boron compounds as potential HIV-1 protease inhibitors

    Czech Academy of Sciences Publication Activity Database

    Plešek, Jaromír; Grüner, Bohumír; Král, V.; Cígler, Petr; Kožíšek, Milan; Prejdová, Jana; Pokorná, Jana; Kräusslich, H. G.; Bodem, J.; Konvalinka, Jan

    Tohoku: Graduate School of Science, 2005, s. 46. [International Conference on Boron Chemistry /12./. Sendai (JP), 11.09.2005-15.09.2005] R&D Projects: GA MŠk(CZ) LC523 Institutional research plan: CEZ:AV0Z40320502 Keywords : boron cluster compounds Subject RIV: CA - Inorganic Chemistry

  1. A Photoelectron Spectroscopy and ab initio Study of B3- and B4- Anions and Their Neutrals

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Hua-Jin; Wang, Lai S.; Alexandrova, A N.; Boldyrev, Alexander I.; Zakrzewski, V G.

    2003-11-06

    The two smallest boron clusters (B3 and B4) in their neutral and anionic forms were studied by photoelectron spectroscopy and ab initio calculations. Vibrationally resolved photoelectron spectra were observed for B3- at three photon energies (355, 266, and 193 nm) and the electron affinity of B3 was measured to be+0.02 eV.

  2. Improving Hydration Resistance of A1 Powder for Carbon Containing Castables Using Inorganic- Organic Hybrid Coatings%采用无机-有机复合涂层改进含碳浇注料铝粉的抗水合性能

    Institute of Scientific and Technical Information of China (English)

    王刚

    2005-01-01

    在60℃和100℃的水中放置36h,通过确定相和显微结构变化来研究未涂覆和涂覆无机-有机复合涂层的铝粉的水合性能,指明其抗水合性能得到显著改善.在空气气氛中于1250℃下放置1.5h,研究了与未涂覆和涂覆无机-有机复合涂层的铝粉共存的石墨的抗氧化性能.与有涂层的铝粉共存的石墨的氧化率相似于与无涂层的铝粉共存的石墨的氧化率,指明两种铝粉具有相似的抗氧化性.抗氧化性方面的极小变化以及抗水合性的显著改善,使得有涂层的铝粉作为潜在的抗氧化剂使用于含碳浇注料系统中.

  3. A Comparative Theoretical and Computational Study on Robust Counterpart Optimization: I. Robust Linear Optimization and Robust Mixed Integer Linear Optimization

    OpenAIRE

    Li, Zukui; Ding, Ran; Floudas, Christodoulos A

    2011-01-01

    Robust counterpart optimization techniques for linear optimization and mixed integer linear optimization problems are studied in this paper. Different uncertainty sets, including those studied in literature (i.e., interval set; combined interval and ellipsoidal set; combined interval and polyhedral set) and new ones (i.e., adjustable box; pure ellipsoidal; pure polyhedral; combined interval, ellipsoidal, and polyhedral set) are studied in this work and their geometric relationship is discusse...

  4. Evidence for an intrinsic binding force between dodecaborate dianions and receptors with hydrophobic binding pockets.

    Science.gov (United States)

    Warneke, Jonas; Jenne, Carsten; Bernarding, Johannes; Azov, Vladimir A; Plaumann, Markus

    2016-05-01

    A gas phase binding study revealed strong intrinsic intermolecular interactions between dianionic halogenated closo-dodecaborates [B12X12](2-) and several neutral organic receptors. Oxidation of a tetrathiafulvalene host allowed switching between two host-guest binding modes in a supramolecular complex. Complexes of β-cyclodextrin with [B12F12](2-) show remarkable stability in the gas phase and were successfully tested as carriers for the delivery of boron clusters into cancer cells. PMID:27087168

  5. Targeted Rapid Synthesis of Redox-Active Dodecaborane Clusters

    OpenAIRE

    Wixtrom, Alex Ian

    2015-01-01

    We have developed a fast, efficient route to obtain targeted perfunctionalized ether-linked alkyl and benzyl derivatives of the closo-[B12(OH)12]2- icosahedral dodecaborate cluster via microwave-assisted synthesis. These icosahedral boron clusters exhibit unique properties including three-dimensional delocalization of the cage-bonding electrons, tunable photophysical properties, and a high degree of stability in air in both solid and solution states. Several B12(OR)12 clusters have been prepa...

  6. The B32 cluster has the most stable bowl structure with a remarkable heptagonal hole.

    Science.gov (United States)

    Tai, Truong Ba; Nguyen, Minh Tho

    2015-05-01

    The neutral B32 exhibits an aromatic bowl structure containing one heptagonal hole, while two anionic species, one having a bowl structure and the other a quasi-planar structure, are almost degenerate in energy. These findings not only give more insight into the structural features of boron clusters, but also present a key result explaining the presence of heptagonal holes in the fullerene B40. PMID:25845816

  7. Exo-substituent effects in halogenated icosahedral (B12H12 2 - ) and octahedral (B6H6 2 - ) closo-borane skeletons: Chemical reactivity studied by experimental and quantum chemical methods

    Czech Academy of Sciences Publication Activity Database

    Lepšík, Martin; Srnec, Martin; Hnyk, Drahomír; Grüner, Bohumír; Plešek, Jaromír; Havlas, Zdeněk; Rulíšek, Lubomír

    2009-01-01

    Roč. 74, č. 1 (2009), s. 1-27. ISSN 0010-0765 R&D Projects: GA MŠk LC523; GA MŠk LC512 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z40320502 Keywords : boranes * boron clusters * halogenations * DFT * ab initio calculations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.856, year: 2009

  8. Electrochemistry of closo-dodecaborate dianion and its simple exo-skeletal derivatives at carbon electrodes in aqueous phosphate buffers

    Czech Academy of Sciences Publication Activity Database

    Fojt, Lukáš; Fojta, Miroslav; Grüner, Bohumír; Vespalec, Radim

    2013-01-01

    Roč. 707, OCT152013 (2013), s. 38-42. ISSN 1572-6657 R&D Projects: GA ČR(CZ) GBP206/12/G151 Institutional research plan: CEZ:AV0Z50040702 Institutional support: RVO:68081707 ; RVO:61388980 Keywords : Boron cluster * Dodecarborate * Glasy carbon electrode Subject RIV: BO - Biophysics; CA - Inorganic Chemistry (UACH-T) Impact factor: 2.871, year: 2013

  9. Lasing characteristics of difluoroborates of 2,2'-dipyrromethene derivatives in solid matrices

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsova, R T; Aksenova, Yu V; Solodova, T A; Kopylova, T N; Tel' minov, E N; Mayer, G V [National Research Tomsk State University (Russian Federation); Berezin, M B; Antina, E V; Burkova, S L [Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo (Russian Federation); Semeikin, A S [Ivanovo State University of Chemistry and Technology, Ivanovo (Russian Federation)

    2014-03-28

    The luminescence-spectral, lasing and photochemical characteristics of laser media based on boron fluoride complexes of dipyrromethenes, embedded into solid bulk matrices of polymethylmethacrylate and its modifications (obtained by adding polyhedral oligomeric silsesquioxane during polymerisation) and into polymer films, in which polyhedral silsesquioxane enters the composition of monomeric unit, have been investigated. (lasers)

  10. Glassy dynamics of convex polyhedra

    NARCIS (Netherlands)

    Tasios, Nikos; Gantapara, Anjan Prasad; Dijkstra, Marjolein

    2014-01-01

    Self-assembly of polyhedral-shaped particles has attracted huge interest with the advent of new synthesis methods that realize these faceted particles in the lab. Recent studies have shown that polyhedral-shaped particles exhibit a rich phase behavior by excluded volume interactions alone; some of t

  11. Convergence of hausdorff approximation methods for the Edgeworth-Pareto hull of a compact set

    Science.gov (United States)

    Efremov, R. V.

    2015-11-01

    The Hausdorff methods comprise an important class of polyhedral approximation methods for convex compact bodies, since they have an optimal convergence rate and possess other useful properties. The concept of Hausdorff methods is extended to a problem arising in multicriteria optimization, namely, to the polyhedral approximation of the Edgeworth-Pareto hull (EPH) of a convex compact set. It is shown that the sequences of polyhedral sets generated by Hausdorff methods converge to the EPH to be approximated. It is shown that the Estimate Refinement method, which is most frequently used to approximate the EPH of convex compact sets, is a Hausdorff method and, hence, generates sequences of sets converging to the EPH.

  12. A non-linear constrained optimization technique for the mimetic finite difference method

    Energy Technology Data Exchange (ETDEWEB)

    Manzini, Gianmarco [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Svyatskiy, Daniil [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bertolazzi, Enrico [Univ. of Trento (Italy); Frego, Marco [Univ. of Trento (Italy)

    2014-09-30

    This is a strategy for the construction of monotone schemes in the framework of the mimetic finite difference method for the approximation of diffusion problems on unstructured polygonal and polyhedral meshes.

  13. On Alternative Optimal Solutions to Linear Fractional Optimization Problems

    Institute of Scientific and Technical Information of China (English)

    ShengjiaXue

    2004-01-01

    The structure of the optimal solution set is derived for linear fractional optimization problems with the representation theorem of polyhedral sets.And the computational procedure in determining all optimal solutions is also given.

  14. Problems around 3-manifolds

    OpenAIRE

    Rubinstein, J Hyam

    2009-01-01

    This is a personal view of some problems on minimal surfaces, Ricci flow, polyhedral geometric structures, Haken 4-manifolds, contact structures and Heegaard splittings, singular incompressible surfaces after the Hamilton-Perelman revolution.

  15. Gaussian Probabilities and Expectation Propagation

    OpenAIRE

    Cunningham, John P.; Hennig, Philipp; Lacoste-Julien, Simon

    2011-01-01

    While Gaussian probability densities are omnipresent in applied mathematics, Gaussian cumulative probabilities are hard to calculate in any but the univariate case. We study the utility of Expectation Propagation (EP) as an approximate integration method for this problem. For rectangular integration regions, the approximation is highly accurate. We also extend the derivations to the more general case of polyhedral integration regions. However, we find that in this polyhedral case, EP's answer...

  16. Inequalities from Poisson brackets

    OpenAIRE

    Alekseev, Anton; Davydenkova, Irina

    2015-01-01

    We introduce the notion of tropicalization for Poisson structures on $\\mathbb{R}^n$ with coefficients in Laurent polynomials. To such a Poisson structure we associate a polyhedral cone and a constant Poisson bracket on this cone. There is a version of this formalism applicable to $\\mathbb{C}^n$ viewed as a real Poisson manifold. In this case, the tropicalization gives rise to a completely integrable system with action variables taking values in a polyhedral cone and angle variables spanning a...

  17. Hybrid polymer networks as ultra low `k` dielectric layers

    Science.gov (United States)

    Lewicki, James; Worsley, Marcus A.

    2016-02-16

    According to one embodiment, a polymeric material includes at least one polydimethylsiloxane (PDMS) polymer, and at least one polyhedral oligomericsilsequioxane (POSS) molecule. According to another embodiment, a method includes providing at least one polydimethylsiloxane (PDMS) polymer, providing at least one polyhedral oligomericsilsequioxane (POSS) molecule, and coupling the at least one PDSM polymer to the at least one POSS molecule to form a hybrid polymeric material.

  18. Monoclonal antibody against boron carriers of BNCT. Part 1. Preparation and characterization of anti mercaptoundecahydrododecaborate antibody (anti-BSH MAb)

    International Nuclear Information System (INIS)

    The monoclonal antibody against mercaptoundecahydrododecaborate (BSH) was prepared, which recognized specifically the icosahedral boron cluster moiety and named 'anti-BSH MAb'. The dissociation constant of anti-BSH MAb against BSH was determined, and the cross reactivity was also clarified by using the enzyme-linked immunosorbent assay (ELISA). In addition, the amino acid sequences of the antigen-binding site in the variable region of heavy and light chains were partly determined and characterized upon protein database. Furthermore, a highly specific, rapid and practical immunoassay for BSH including quantitative determination of the BSH concentrations in blood by the competitive ELISA system using anti-BSH MAb has been explored. (author)

  19. QM/MM Calculations Reveal the Different Nature of the Interaction of Two Carborane-Based Sulfamide Inhibitors of Human Carbonic Anhydrase II

    Czech Academy of Sciences Publication Activity Database

    Pecina, Adam; Lepšík, Martin; Řezáč, Jan; Brynda, Jiří; Mader, Pavel; Řezáčová, Pavlína; Hobza, Pavel; Fanfrlík, Jindřich

    2013-01-01

    Roč. 117, č. 50 (2013), s. 16096-16104. ISSN 1520-6106 R&D Projects: GA ČR GBP208/12/G016 Grant ostatní: Operational Program Research and Development for Innovations(XE) CZ 1.05/2.1.00/03/0058 Institutional support: RVO:61388963 ; RVO:68378050 Keywords : neutron-capture therapy * dodecaborate cluster lipids * boron clusters Subject RIV: CF - Physical ; Theoretical Chemistry; EB - Genetics ; Molecular Biology (UMG-J) Impact factor: 3.377, year: 2013

  20. Cobalt bis(dicarbollide) ions with covalently bonded CMPO groups as selective extraction agents for lanthanide and actinide cations from highly acidic nuclear waste solutions

    Czech Academy of Sciences Publication Activity Database

    Grüner, Bohumír; Plešek, Jaromír; Báča, Jiří; Císařová, I.; Dozol, J. F.; Rouquette, H.; Vinas, C.; Selucký, P.; Rais, J.

    2002-01-01

    Roč. 26, č. 10 (2002), s. 1519-1527. ISSN 1144-0546 R&D Projects: GA ČR GA104/99/1096; GA ČR GA104/01/0142; GA ČR GA203/99/M037; GA MŠk LN00A028 Institutional research plan: CEZ:AV0Z4032918 Keywords : LIQUID-CHROMATOGRAPHIC SEPARATIONS * BORON-CLUSTER COMPOUNDS * CALIXARENES Subject RIV: CA - Inorganic Chemistry Impact factor: 2.060, year: 2002

  1. Beyond organic chemistry: aromaticity in atomic clusters.

    Science.gov (United States)

    Boldyrev, Alexander I; Wang, Lai-Sheng

    2016-04-28

    We describe joint experimental and theoretical studies carried out collaboratively in the authors' labs for understanding the structures and chemical bonding of novel atomic clusters, which exhibit aromaticity. The concept of aromaticity was first discovered to be useful in understanding the square-planar unit of Al4 in a series of MAl4(-) bimetallic clusters that led to discoveries of aromaticity in many metal cluster systems, including transition metals and similar cluster motifs in solid compounds. The concept of aromaticity has been found to be particularly powerful in understanding the stability and bonding in planar boron clusters, many of which have been shown to be analogous to polycyclic aromatic hydrocarbons in their π bonding. Stimulated by the multiple aromaticity in planar boron clusters, a design principle has been proposed for stable metal-cerntered aromatic molecular wheels of the general formula, M@Bn(k-). A series of such borometallic aromatic wheel complexes have been produced in supersonic cluster beams and characterized experimentally and theoretically, including Ta@B10(-) and Nb@B10(-), which exhibit the highest coordination number in two dimensions. PMID:26864511

  2. Three-chain B{sub 6n+14} cages as possible precursors for the syntheses of boron fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Haigang, E-mail: luhg@sxu.edu.cn; Li, Si-Dian [Key Laboratory of Chemical Biology and Molecular Engineering of the Education Ministry, Institute of Molecular Science, Shanxi University, Taiyuan, Shanxi 030006 (China)

    2013-12-14

    Using the first principle methods, we proposed a series of three-chain boron cages B{sub 6n+14} (n = 1–12) which are mainly built by fusing three boron semi-double-rings. Their simple geometric structures (approximate D{sub 3} or C{sub 3} symmetry) facilitate their bottom-up syntheses from the hexagonal B{sub 7} and the double-chain boron clusters, such as B{sub 2}, B{sub 4}, B{sub 6}, B{sub 8}H{sub 2}, B{sub 10}H{sub 2}, B{sub 12}H{sub 2}, and the double ring B{sub 20}. The spherical shapes of these three-chain boron cages show that they could be taken as the possible precursors to further synthesize the boron fullerenes, such as B{sub 80}. Therefore, these three-chain boron cages provide a possible synthesis pathway of the boron fullerenes from the experimentally synthesized small planar boron clusters.

  3. Isotope analysis of carbon by C2 molecule spectrum

    International Nuclear Information System (INIS)

    A study was made on inert gas mixture (He, Ne, Ar) with carbon-containing components (CO, CO2, CH4) under conditions of variation of mixture pressure in discharge tube, of carbon-containing components contents and the rate of gas flow through the discharge tube. The use of C2 molecule spectrum enabled to develope the spectroscopic techniques for determination of carbon isotope ratio. The method is universal with respect to molecular form of carbon-containing substance

  4. Estudo ultra-estrutural do esôfago de Trichogenes longipinnis (Britski & Ortega (Pisces, Siluriformes, Trichomicteridae Ultrastructural study of the oesophagous of Trichogenes longipinnis (Britski & Ortega (Pisces, Siluriformes, Trichomicteridae

    Directory of Open Access Journals (Sweden)

    Nadja Lima Pinheiro

    1993-01-01

    Full Text Available Trichogenes longipinnis (Britski & Ortega, 1983 is a leather fish restricted to the rivers on the shore in the southeast of Brazil. In this work, the oesophagous structure is being showed. The oesophagous appears itself short, dorsally inclinated toward pericardium and ventrally covered by liver lobe. By electron microscopy we can observe a mucosa layer formed by stratified squamous epithelium and lamina propria with stratum compactum. The epithelium is composed by three types of cells: superficial squamous cells; mucous cells, similar to the globet cells and polyhedric cells. The stratification of this epithelium provides a complete basal layer of proliferation polyhedric cells. The cells in the intermediate region of the epithelium are also polyhedric. These cells are just bellow the superficial squamous cells and packed among mucous cells.

  5. An Origami Approximation to the Cosmic Web

    CERN Document Server

    Neyrinck, Mark C

    2014-01-01

    The powerful Lagrangian view of structure formation was essentially introduced to cosmology by Zel'dovich. In the current cosmological paradigm, a dark-matter-sheet 3D manifold, inhabiting 6D position-velocity phase space, was flat (with vanishing velocity) at the big bang. Afterward, gravity stretched and bunched the sheet together in different places, forming a cosmic web when projected to the position coordinates. Here, I explain some properties of an origami approximation, in which the sheet does not stretch or contract (an assumption that is false in general), but is allowed to fold. Even without stretching, the sheet can form an idealized cosmic web, with convex polyhedral voids separated by straight walls and filaments, joined by convex polyhedral nodes. The nodes form in 'polygonal' or 'polyhedral' collapse, somewhat like spherical/ellipsoidal collapse, except incorporating simultaneous filament and wall formation. The origami approximation allows phase-space geometries of nodes, filaments, and walls ...

  6. Some results from a study of carbon minerals by the thermal method

    Energy Technology Data Exchange (ETDEWEB)

    Otakuziyev, E.; Kasymov, A.K.; Miralimova, N.M.

    1979-01-01

    Using the optimum technique of thermal analysis in carbon-containing shales and hornfels of ancient deposits of the Kyzylkum and Zirabulak-Ziaetdinsk mountains, four groups are revealed of mineral form of carbon, corresponding to the kerite-oxykeriteanthraxolite-shungite-graphite series. Interpretation of the thermograms obtained shows the varying degree of metamorphism of the carbon-containing rock of the areas studied.

  7. Method of producing carbon coated nano- and micron-scale particles

    Science.gov (United States)

    Perry, W. Lee; Weigle, John C; Phillips, Jonathan

    2013-12-17

    A method of making carbon-coated nano- or micron-scale particles comprising entraining particles in an aerosol gas, providing a carbon-containing gas, providing a plasma gas, mixing the aerosol gas, the carbon-containing gas, and the plasma gas proximate a torch, bombarding the mixed gases with microwaves, and collecting resulting carbon-coated nano- or micron-scale particles.

  8. Electrorheological fluids and methods

    Energy Technology Data Exchange (ETDEWEB)

    Green, Peter F.; McIntyre, Ernest C.

    2015-06-02

    Electrorheological fluids and methods include changes in liquid-like materials that can flow like milk and subsequently form solid-like structures under applied electric fields; e.g., about 1 kV/mm. Such fluids can be used in various ways as smart suspensions, including uses in automotive, defense, and civil engineering applications. Electrorheological fluids and methods include one or more polar molecule substituted polyhedral silsesquioxanes (e.g., sulfonated polyhedral silsesquioxanes) and one or more oils (e.g., silicone oil), where the fluid can be subjected to an electric field.

  9. Minkowski sum of HV-polytopes in Rn

    CERN Document Server

    Delos, Vincent

    2014-01-01

    Minkowski sums cover a wide range of applications in many different fields like algebra, morphing, robotics, mechanical CAD/CAM systems ... This paper deals with sums of polytopes in a n dimensional space provided that both H-representation and V-representation are available i.e. the polytopes are described by both their half-spaces and vertices. The first method uses the polytope normal fans and relies on the ability to intersect dual polyhedral cones. Then we introduce another way of considering Minkowski sums of polytopes based on the primal polyhedral cones attached to each vertex.

  10. Design of survivable networks

    CERN Document Server

    Stoer, Mechthild

    1992-01-01

    The problem of designing a cost-efficient network that survives the failure of one or more nodes or edges of the network is critical to modern telecommunications engineering. The method developed in this book is designed to solve such problems to optimality. In particular, a cutting plane approach is described, based on polyhedral combinatorics, that is ableto solve real-world problems of this type in short computation time. These results are of interest for practitioners in the area of communication network design. The book is addressed especially to the combinatorial optimization community, but also to those who want to learn polyhedral methods. In addition, interesting new research problemsare formulated.

  11. Contrasting pH buffering patterns in neutral-alkaline soils along a 3600 km transect in northern China

    Directory of Open Access Journals (Sweden)

    W. Luo

    2015-08-01

    Full Text Available Soil pH buffering capacity (pHBC plays a crucial role in predicting acidification rates, yet its large-scale patterns and controls are poorly understood, especially for neutral-alkaline soils. Here, we evaluated the spatial patterns and drivers of pHBC along a 3600 km long transect (1900 km sub-transect with carbonate containing soils and 1700 km sub-transect with non-carbonate containing soils across northern China. Soil pHBC was greater in the carbonate containing soils than in the non-carbonate containing soils. Acid addition decreased soil pH in the non-carbonate containing soils more markedly than in the carbonate containing soils. Within the carbonate soil sub-transect, soil pHBC was positively correlated with cation exchange capacity (CEC, carbonate content and exchangeable sodium (Na concentration, but negatively correlated with initial pH and clay content, and not correlated with soil organic carbon (SOC content. Within the non-carbonate sub-transect, soil pHBC was positively related to initial pH, clay content, CEC and exchangeable Na concentration, but not related to SOC content. Carbonate content was the primary determinant of pHBC in the carbonate containing soils and CEC was the main determinant of buffering capacity in the non-carbonate containing soils. Soil pHBC was positively related to aridity index and carbonate content across the carbonate containing soil sub-transect. Our results indicated that mechanisms controlling pHBC differ among neutral-alkaline soils of northern China, especially between carbonate and non-carbonate containing soils, leading to different rates, risks, and impacts of acidification. This understanding should be incorporated into the acidification risk assessment and landscape management in a changing world.

  12. Crystal growth and anisotropy of high temperature thermoelectric properties of yttrium borosilicide single crystals

    Science.gov (United States)

    Hossain, M. Anwar; Tanaka, Isao; Tanaka, Takaho; Khan, A. Ullah; Mori, Takao

    2016-01-01

    We studied thermoelectric properties of YB41Si1.3 single crystals grown by the floating zone method. The composition of the grown crystal was confirmed by electron probe micro-analysis. We have determined the growth direction for the first time for these borosilicides, and discovered relatively large anisotropy in electrical properties. We measured the electrical resistivity and Seebeck coefficient along [510] (the growth direction) and [052] directions and we found that this crystal exhibits strong electrical anisotropy with a maximum of more than 8 times. An interesting layered structural feature is revealed along [510] with dense boron cluster layers and yttrium layers, with conductivity enhanced along this direction. We obtained 3.6 times higher power factor along [510] compared to that along [052]. Although the ZT of the present system is low, anisotropy in the thermoelectric properties of a boride was reported for the first time, and can be a clue in developing other boride systems also.

  13. Folic acid derivatives for PET imaging and therapy addressing folate receptor positive tumors

    International Nuclear Information System (INIS)

    Folic acid, also known as vitamin B9, is the oxidized form of 5,6,7,8-tetrahydrofolate, which serves as methyl- or methylene donor (C1-building blocks) during DNA synthesis. Under physiological conditions the required amount of 5,6,7,8-tetrahydrofolate for survival of the cell is accomplished through the reduced folate carrier (RFC). In contrast, the supply of 5,6,7,8-tetrahydrofolate is insufficient under pathophysiological conditions of tumors due to an increased proliferation rate. Consequently, many tumor cells exhibit an (over)expression of the folate receptor. This phenomenon has been applied to diagnostics (PET, SPECT, MR) to image FR-positive tumors and on the other hand to treat malignancies related to a FR (over)expression. Based on this concept, a new 18F-labeled folate for PET imaging has been developed and was evaluated in vivo using tumor-bearing mice. The incorporation of oligoethylene spacers into the molecular structure led to a significant enhancement of the pharmacokinetics in comparison to previously developed 18F-folates. The liver uptake could be reduced by one sixth by remaining a tumor uptake of 3%ID/g leading to better contrast ratios. Encouraged by these results, a clickable 18F-labeled serine-based prosthetic group has been synthesized, again with the idea to improve the metabolic and pharmacokinetic profile of hydrophilic radiotracers. Therefore, an alkyne-carrying azido-functionalized serine derivative for coupling to biomolecules was synthesized and a chlorine leaving group for 18F-labeling, which could be accomplished using a microwave-assisted synthesis, a [K is contained in 2.2.2]+/carbonate system in DMSO. Radiochemical yields of 77±6% could be achieved. The promising results obtained from the FR-targeting concept in the diagnostic field have been transferred to the boron neutron capture therapy. Therefore, a folate derivative was coupled to different boron clusters and cell uptake studies were conducted. The synthesis of the

  14. Study of Magnesium Diboride Clusters Using Hybrid Density Functional Theory

    Directory of Open Access Journals (Sweden)

    D. Rodríguez

    2008-01-01

    Full Text Available Using hybrid density functional theory and a relatively large basis set, the lowest energy equilibrium structure, vibrational spectrum, and natural orbital analysis were obtained for magnesium diboride clusters [(MgB2x for x=1,2, and 3]. For comparison, boron clusters [Bx for x=2,4, and 6] were also considered. The MgB2 and (MgB22 showed equilibrium structures with the boron atoms in arrangements similar to what was obtained for pure boron atoms, whereas, for (MgB23 a different arrangement of boron was obtained. From the population analysis, large electron density in the boron atoms forming the clusters was observed.

  15. Organic non-aqueous cation-based redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, Andrew N.; Vaughey, John T.; Chen, Zonghai; Zhang, Lu; Brushett, Fikile R.

    2016-03-29

    The present invention provides a non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator (e.g., a porous membrane, film, sheet, or panel) between the negative electrolyte from the positive electrolyte. During charging and discharging, the electrolytes are circulated over their respective electrodes. The electrolytes each comprise an electrolyte salt (e.g., a lithium or sodium salt), a transition-metal free redox reactant, and optionally an electrochemically stable organic solvent. Each redox reactant is selected from an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof. The organic redox reactant of the positive electrolyte is selected to have a higher redox potential than the redox reactant of the negative electrolyte.

  16. Theory of Linear Optical Absorption in B_12 Clusters: Role of the geometry

    CERN Document Server

    Sahu, Sridhar

    2009-01-01

    Boron clusters have been widely studied theoretically for their geometrical properties and electronic structure using a variety of methodologies. An important cluster of boron is the B$_{12}$ cluster whose two main isomers have distinct geometries, namely, icosahedral ($I_{h}$) and quasi planar ($C_{3v}$). In this paper we investigate the linear optical absorption spectrum of these two B$_{12}$ structures with the aim of examining the role of geometry on the optical properties of clusters. The optical absorption calculations are performed using both the semi-empirical and the ab initio approaches. The semi-empirical approach uses a wave function methodology employing the INDO model Hamiltonian, coupled with large-scale configuration interaction (CI) calculations, to account for the electron-correlation effects. The \\emph{ab initio} calculations are performed within a time-dependent-density-functional-theory (TDDFT) methodology. The results for the two approaches are in very good qualitative agreement with eac...

  17. Folic acid derivatives for PET imaging and therapy addressing folate receptor positive tumors

    Energy Technology Data Exchange (ETDEWEB)

    Schieferstein, Hanno

    2013-07-01

    Folic acid, also known as vitamin B9, is the oxidized form of 5,6,7,8-tetrahydrofolate, which serves as methyl- or methylene donor (C1-building blocks) during DNA synthesis. Under physiological conditions the required amount of 5,6,7,8-tetrahydrofolate for survival of the cell is accomplished through the reduced folate carrier (RFC). In contrast, the supply of 5,6,7,8-tetrahydrofolate is insufficient under pathophysiological conditions of tumors due to an increased proliferation rate. Consequently, many tumor cells exhibit an (over)expression of the folate receptor. This phenomenon has been applied to diagnostics (PET, SPECT, MR) to image FR-positive tumors and on the other hand to treat malignancies related to a FR (over)expression. Based on this concept, a new {sup 18}F-labeled folate for PET imaging has been developed and was evaluated in vivo using tumor-bearing mice. The incorporation of oligoethylene spacers into the molecular structure led to a significant enhancement of the pharmacokinetics in comparison to previously developed {sup 18}F-folates. The liver uptake could be reduced by one sixth by remaining a tumor uptake of 3%ID/g leading to better contrast ratios. Encouraged by these results, a clickable {sup 18}F-labeled serine-based prosthetic group has been synthesized, again with the idea to improve the metabolic and pharmacokinetic profile of hydrophilic radiotracers. Therefore, an alkyne-carrying azido-functionalized serine derivative for coupling to biomolecules was synthesized and a chlorine leaving group for {sup 18}F-labeling, which could be accomplished using a microwave-assisted synthesis, a [K is contained in 2.2.2]{sup +}/carbonate system in DMSO. Radiochemical yields of 77±6% could be achieved. The promising results obtained from the FR-targeting concept in the diagnostic field have been transferred to the boron neutron capture therapy. Therefore, a folate derivative was coupled to different boron clusters and cell uptake studies were

  18. Aggregation-Induced Delayed Fluorescence Based on Donor/Acceptor-Tethered Janus Carborane Triads: Unique Photophysical Properties of Nondoped OLEDs.

    Science.gov (United States)

    Furue, Ryuhei; Nishimoto, Takuro; Park, In Seob; Lee, Jiyoung; Yasuda, Takuma

    2016-06-13

    Luminescent materials consisting of boron clusters, such as carboranes, have attracted immense interest in recent years. In this study, luminescent organic-inorganic conjugated systems based on o-carboranes directly bonded to electron-donating and electron-accepting π-conjugated units were elaborated as novel optoelectronic materials. These o-carborane derivatives simultaneously possessed aggregation-induced emission (AIE) and thermally activated delayed fluorescence (TADF) capabilities, and showed strong yellow-to-red emissions with high photoluminescence quantum efficiencies of up to 97 % in their aggregated states or in solid neat films. Organic light-emitting diodes utilizing these o-carborane derivatives as a nondoped emission layer exhibited maximum external electroluminescence quantum efficiencies as high as 11 %, originating from TADF. PMID:27145481

  19. Next generation of the self-consistent and environment-dependent Hamiltonian: Applications to various boron allotropes from zero- to three-dimensional structures

    Energy Technology Data Exchange (ETDEWEB)

    Tandy, P.; Yu, Ming; Leahy, C.; Jayanthi, C. S.; Wu, S. Y. [Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40292 (United States)

    2015-03-28

    An upgrade of the previous self-consistent and environment-dependent linear combination of atomic orbitals Hamiltonian (referred as SCED-LCAO) has been developed. This improved version of the semi-empirical SCED-LCAO Hamiltonian, in addition to the inclusion of self-consistent determination of charge redistribution, multi-center interactions, and modeling of electron-electron correlation, has taken into account the effect excited on the orbitals due to the atomic aggregation. This important upgrade has been subjected to a stringent test, the construction of the SCED-LCAO Hamiltonian for boron. It was shown that the Hamiltonian for boron has successfully characterized the electron deficiency of boron and captured the complex chemical bonding in various boron allotropes, including the planar and quasi-planar, the convex, the ring, the icosahedral, and the fullerene-like clusters, the two-dimensional monolayer sheets, and the bulk alpha boron, demonstrating its transferability, robustness, reliability, and predictive power. The molecular dynamics simulation scheme based on the Hamiltonian has been applied to explore the existence and the energetics of ∼230 compact boron clusters B{sub N} with N in the range from ∼100 to 768, including the random, the rhombohedral, and the spherical icosahedral structures. It was found that, energetically, clusters containing whole icosahedral B{sub 12} units are more stable for boron clusters of larger size (N > 200). The ease with which the simulations both at 0 K and finite temperatures were completed is a demonstration of the efficiency of the SCED-LCAO Hamiltonian.

  20. Next generation of the self-consistent and environment-dependent Hamiltonian: Applications to various boron allotropes from zero- to three-dimensional structures

    International Nuclear Information System (INIS)

    An upgrade of the previous self-consistent and environment-dependent linear combination of atomic orbitals Hamiltonian (referred as SCED-LCAO) has been developed. This improved version of the semi-empirical SCED-LCAO Hamiltonian, in addition to the inclusion of self-consistent determination of charge redistribution, multi-center interactions, and modeling of electron-electron correlation, has taken into account the effect excited on the orbitals due to the atomic aggregation. This important upgrade has been subjected to a stringent test, the construction of the SCED-LCAO Hamiltonian for boron. It was shown that the Hamiltonian for boron has successfully characterized the electron deficiency of boron and captured the complex chemical bonding in various boron allotropes, including the planar and quasi-planar, the convex, the ring, the icosahedral, and the fullerene-like clusters, the two-dimensional monolayer sheets, and the bulk alpha boron, demonstrating its transferability, robustness, reliability, and predictive power. The molecular dynamics simulation scheme based on the Hamiltonian has been applied to explore the existence and the energetics of ∼230 compact boron clusters BN with N in the range from ∼100 to 768, including the random, the rhombohedral, and the spherical icosahedral structures. It was found that, energetically, clusters containing whole icosahedral B12 units are more stable for boron clusters of larger size (N > 200). The ease with which the simulations both at 0 K and finite temperatures were completed is a demonstration of the efficiency of the SCED-LCAO Hamiltonian

  1. Next generation of the self-consistent and environment-dependent Hamiltonian: Applications to various boron allotropes from zero- to three-dimensional structures

    Science.gov (United States)

    Tandy, P.; Yu, Ming; Leahy, C.; Jayanthi, C. S.; Wu, S. Y.

    2015-03-01

    An upgrade of the previous self-consistent and environment-dependent linear combination of atomic orbitals Hamiltonian (referred as SCED-LCAO) has been developed. This improved version of the semi-empirical SCED-LCAO Hamiltonian, in addition to the inclusion of self-consistent determination of charge redistribution, multi-center interactions, and modeling of electron-electron correlation, has taken into account the effect excited on the orbitals due to the atomic aggregation. This important upgrade has been subjected to a stringent test, the construction of the SCED-LCAO Hamiltonian for boron. It was shown that the Hamiltonian for boron has successfully characterized the electron deficiency of boron and captured the complex chemical bonding in various boron allotropes, including the planar and quasi-planar, the convex, the ring, the icosahedral, and the fullerene-like clusters, the two-dimensional monolayer sheets, and the bulk alpha boron, demonstrating its transferability, robustness, reliability, and predictive power. The molecular dynamics simulation scheme based on the Hamiltonian has been applied to explore the existence and the energetics of ˜230 compact boron clusters BN with N in the range from ˜100 to 768, including the random, the rhombohedral, and the spherical icosahedral structures. It was found that, energetically, clusters containing whole icosahedral B12 units are more stable for boron clusters of larger size (N > 200). The ease with which the simulations both at 0 K and finite temperatures were completed is a demonstration of the efficiency of the SCED-LCAO Hamiltonian.

  2. Uniqueness in inverse elastic scattering with finitely many incident waves

    Energy Technology Data Exchange (ETDEWEB)

    Elschner, Johannes [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) im Forschungsverbund Berlin e.V. (Germany); Yamamoto, Masahiro [Tokyo Univ. (Japan). Dept. of Mathematical Sciences

    2009-07-01

    We consider the third and fourth exterior boundary value problems of linear isotropic elasticity and present uniqueness results for the corresponding inverse scattering problems with polyhedral-type obstacles and a finite number of incident plane elastic waves. Our approach is based on a reflection principle for the Navier equation. (orig.)

  3. Bacterial Microcompartments

    OpenAIRE

    Kerfeld, Cheryl A.

    2010-01-01

    Bacterialmicrocompartments (BMCs) are organelles composed entirely of protein. They promote specific metabolic processes by encapsulating and colocalizing enzymes with their substrates and cofactors, by protecting vulnerable enzymes in a defined microenvironment, and by sequestering toxic or volatile intermediates. Prototypes of the BMCsare the carboxysomes of autotrophic bacteria. However, structures of similar polyhedral shape are being discovered in an ever-increasing number of heterotroph...

  4. Convergency analysis of the high-order mimetic finite difference method

    Energy Technology Data Exchange (ETDEWEB)

    Lipnikov, Konstantin [Los Alamos National Laboratory; Veiga Da Beirao, L [UNIV DEGLI STUDI; Manzini, G [NON LANL

    2008-01-01

    We prove second-order convergence of the conservative variable and its flux in the high-order MFD method. The convergence results are proved for unstructured polyhedral meshes and full tensor diffusion coefficients. For the case of non-constant coefficients, we also develop a new family of high-order MFD methods. Theoretical result are confirmed through numerical experiments.

  5. Synthesis of defined POSS-containing diblock and triblock methacrylate copolymers by ATRP

    Czech Academy of Sciences Publication Activity Database

    Janata, Miroslav; Raus, Vladimír; Sikora, Antonín; Čadová, Eva; Látalová, Petra

    Pisa : European Polymer Federation, 2013. P1-41. [European Polymer Congress - EPF 2013. 16.06.2013-21.06.2013, Pisa] R&D Projects: GA ČR GAP106/12/0844 Institutional support: RVO:61389013 Keywords : atom transfer radical polymerization * block copolymers * polyhedral oligosilsesquioxanes Subject RIV: CD - Macromolecular Chemistry

  6. The Generation of Curved Clathrin Coats from Flat Plaques

    NARCIS (Netherlands)

    Otter, den Wouter K.; Briels, Wim J.

    2011-01-01

    Flat clathrin lattices or ‘plaques’ are commonly believed to be the precursors to clathrin-coated buds and vesicles. The sequence of steps carrying the flat hexagonal lattice into a highly curved polyhedral cage with exactly 12 pentagons remains elusive, however, and the large numbers of disrupted i

  7. Polyhedra [LnOn]: coordination numbers, shape, interpolyhedral bonds, Zn-O distances

    International Nuclear Information System (INIS)

    Peculiarities of oxygen atoms positioning in the nearest surrounding of rare earth elements are studied. Main characteristics of coordination polyhedra (LnOn): shape, vertex number and interatomic distances. Peculiarities of their change in the rare earth elements series are revealed. It is shown by example of icosahedron and cube that fragmentation processes form in many case the basis of mechanisms of polyhedral transformations

  8. Demonstration of a 3D vision algorithm for space applications

    Science.gov (United States)

    Defigueiredo, Rui J. P. (Editor)

    1987-01-01

    This paper reports an extension of the MIAG algorithm for recognition and motion parameter determination of general 3-D polyhedral objects based on model matching techniques and using movement invariants as features of object representation. Results of tests conducted on the algorithm under conditions simulating space conditions are presented.

  9. Forward Modeling of Gravity, Gravity Gradients,and Magnetic Anomalies due to Complex Bodies

    Institute of Scientific and Technical Information of China (English)

    Luo Yao; Yao Changli

    2007-01-01

    On the basis of the results of improved analytical expression of computation of gravity anomalies due to a homogeneous polyhedral body composed of polygonal facets, and applying the forward theory with the coordinate transformation of vectors and tensors, we deduced both the analytical expressions for gravity gradient tensors and for magnetic anomalies of a polygon, and obtained new analytical expressions for computing vertical gradients of gravity anomalies and vertical component of magnetic anomalies caused by a polyhedral body. And also we developed explicitly the complete unified expressions for the calculation of gravity anomalies, gravity gradient, and magnetic anomalies due to the homogeneous polyhedron. Furthermore, we deduced new analytical expressions for computing vertical gradients of gravity anomalies due to a finite rectangular prism by applying the newly obtained expressions for gravity gradient tensors due to a polyhedral target body. Comparison with forward calculation of models shows the correctness of these new expressions. It will reduce forward calculation time of gravity-magnetic anomalies and improve computational efficiency by applying our unified expressions for joint forward modeling of gravity-magnetic anomalies due to homogeneous polyhedral bodies.

  10. Phosphaborane chemistry. Syntheses and calculated molecular structures of mono- and di-chloro derivatives of 1,2-diphospha-closo-dodecaborane(10)

    Czech Academy of Sciences Publication Activity Database

    Grüner, Bohumír; Hnyk, Drahomír; Císařová, I.; Plzák, Zbyněk; Štíbr, Bohumil

    č. 15 (2002), s. 2954-2959. ISSN 1472-7773 R&D Projects: GA ČR GA203/00/1042; GA MŠk LN00A028 Institutional research plan: CEZ:AV0Z4032918 Keywords : crystal-structure * phosphacarborane chemistry * polyhedral phosphaboranes Subject RIV: CA - Inorganic Chemistry Impact factor: 3.023, year: 2002

  11. Boron carbide particles formed from an amorphous boron/graphite powder mixture using a shock-wave technique

    International Nuclear Information System (INIS)

    Boron carbide (B4C) particles with filamental, distorted ellipsoidal, platelike, and polyhedral shapes were formed from vapor generated from an amorphous boron/graphite powder mixture with 14% starting density using a cylindrical shock-wave technique. The crystal phases of shocked compact and microstructures of the B4C particles were characterized by X-ray diffractometry and electron microscopy, respectively

  12. Inequalities Representing Polyhedra

    NARCIS (Netherlands)

    Bosse, H.; Grötschel, M.; Henk, M.

    2005-01-01

    Our main result is that every n-dimensional polytope can be described by at most 2n−1 polynomial inequalities and, moreover, these polynomials can explicitly be constructed. For an n-dimensional pointed polyhedral cone we prove the bound 2n−2 and for arbitrary polyhedra we get a construc

  13. Intelligent Biohybrid Neurotechnologies: Are They Really What They Claim?

    OpenAIRE

    Panuccio, Gabriella; Semprini, Marianna; Natale, Lorenzo; Chiappalone, Michela

    2016-01-01

    In the era of intelligent biohybrid neurotechnologies for brain repair, new fanciful terms are appearing in the scientific dictionary to define what has so far been unimaginable. As the emerging neurotechnologies are becoming increasingly polyhedral and sophisticated, should we talk about evolution and rank the intelligence of these devices?

  14. Robust stabilization via computer-generated Lyapunov functions: An application to a magnetic levitation system

    Energy Technology Data Exchange (ETDEWEB)

    Blanchini, F. [Universita di Udine (Italy); Carabelli, S. [Politecnico di Torino (Italy)

    1994-12-31

    We apply a technique recently proposed in literature for the robust stabilization of linear systems with time-varying uncertain parameters to a magnetic levitation system. This technique allows the construction of a polyhedral Lyapunov function and a linear variable-structure stabilizing controller.

  15. The crystal structures of strontium exchanged sodium titanosilicates in relation to selectivity for nuclear waste treatment

    International Nuclear Information System (INIS)

    A perspective view of the polyhedral representation in Sr exchanged titanosilicate with sitinakite topology. The eight ring tunnel along c-axis depicts a nine coordinated Sr complex. Dark and light gray spheres in the eight ring channel represent water molecules and Sr2+ cations respectively

  16. Synthesis of o- and m-carborane derivatives of 5,10,15,20-tetra-(p-anionphenyl)porphyrin

    International Nuclear Information System (INIS)

    The data on synthesis of o- and m-carborane-containing porphyrins, which derivatives through boron atom of polyhedral nucleus are presented. The reaction of the porphyrin amino group acylation may be used for production of the porphyrin carborane derivative with high boron content (up to 30 %) with the purpose of applying them in boron neutron-capture cancer therapy

  17. The cone conjecture for Calabi-Yau pairs in dimension 2

    OpenAIRE

    Totaro, Burt

    2010-01-01

    We prove the Morrison-Kawamata cone conjecture for Kawamata log terminal Calabi-Yau pairs in dimension $2$ . For a large class of rational surfaces as well as for K3 surfaces and abelian surfaces, the action of the automorphism group of the surface on the convex cone of ample divisors has a rational polyhedral fundamental domain.

  18. Discrete Curvature Theories and Applications

    KAUST Repository

    Sun, Xiang

    2016-08-25

    Discrete Di erential Geometry (DDG) concerns discrete counterparts of notions and methods in di erential geometry. This thesis deals with a core subject in DDG, discrete curvature theories on various types of polyhedral surfaces that are practically important for free-form architecture, sunlight-redirecting shading systems, and face recognition. Modeled as polyhedral surfaces, the shapes of free-form structures may have to satisfy di erent geometric or physical constraints. We study a combination of geometry and physics { the discrete surfaces that can stand on their own, as well as having proper shapes for the manufacture. These proper shapes, known as circular and conical meshes, are closely related to discrete principal curvatures. We study curvature theories that make such surfaces possible. Shading systems of freeform building skins are new types of energy-saving structures that can re-direct the sunlight. From these systems, discrete line congruences across polyhedral surfaces can be abstracted. We develop a new curvature theory for polyhedral surfaces equipped with normal congruences { a particular type of congruences de ned by linear interpolation of vertex normals. The main results are a discussion of various de nitions of normality, a detailed study of the geometry of such congruences, and a concept of curvatures and shape operators associated with the faces of a triangle mesh. These curvatures are compatible with both normal congruences and the Steiner formula. In addition to architecture, we consider the role of discrete curvatures in face recognition. We use geometric measure theory to introduce the notion of asymptotic cones associated with a singular subspace of a Riemannian manifold, which is an extension of the classical notion of asymptotic directions. We get a simple expression of these cones for polyhedral surfaces, as well as convergence and approximation theorems. We use the asymptotic cones as facial descriptors and demonstrate the

  19. The Mechanism of Silicon and Silicon Carbide Making Carbon—containing Materials Antioxidize

    Institute of Scientific and Technical Information of China (English)

    TIANShouxin; SimThiamChee; 等

    1996-01-01

    The paper analyses redox reactions of an-tioxidants Si and SiC ete at different positions in the course of oxidation of carbon-containing materials,It is pointed out that redox reaction of antioxidants in oxidized-zone plays a very important part in antioxidation of carbon-con-taining materials,The reason why SiC can make carbon-containing material antioxide at thermodynamic temperature has been ex-plained,Experiment proves that antioxidants in oxidized zone can make carbon-containing materils antioxidize.

  20. Apparatus and process for the surface treatment of carbon fibers

    Energy Technology Data Exchange (ETDEWEB)

    Paulauskas, Felix Leonard; Ozcan, Soydan; Naskar, Amit K.

    2016-05-17

    A method for surface treating a carbon-containing material in which carbon-containing material is reacted with decomposing ozone in a reactor (e.g., a hollow tube reactor), wherein a concentration of ozone is maintained throughout the reactor by appropriate selection of at least processing temperature, gas stream flow rate, reactor dimensions, ozone concentration entering the reactor, and position of one or more ozone inlets (ports) in the reactor, wherein the method produces a surface-oxidized carbon or carbon-containing material, preferably having a surface atomic oxygen content of at least 15%. The resulting surface-oxidized carbon material and solid composites made therefrom are also described.

  1. Sub-Critical Closed String Field Theory in D Less Than 26

    CERN Document Server

    Kaku, M

    1994-01-01

    We construct the second quantized action for sub-critical closed string field theory with zero cosmological constant in dimensions $ 2 \\leq D < 26$, generalizing the non-polynomial closed string field theory action proposed by the author and the Kyoto and MIT groups for $D = 26$. The proof of gauge invariance is considerably complicated by the presence of the Liouville field $\\phi$ and the non-polynomial nature of the action. However, we explicitly show that the polyhedral vertex functions obey BRST invariance to all orders. By point splitting methods, we calculate the anomaly contribution due to the Liouville field, and show in detail that it cancels only if $D - 26 + 1 + 3 Q ^ 2 = 0 $, in both the bosonized and unbosonized polyhedral vertex functions. We also show explicitly that the four point function generated by this action reproduces the shifted Shapiro-Virasoro amplitude found from $c=1$ matrix models and Liouville theory in two dimensions. LATEX file.

  2. The mimetic finite difference method for elliptic problems

    CERN Document Server

    Veiga, Lourenço Beirão; Manzini, Gianmarco

    2014-01-01

    This book describes the theoretical and computational aspects of the mimetic finite difference method for a wide class of multidimensional elliptic problems, which includes diffusion, advection-diffusion, Stokes, elasticity, magnetostatics and plate bending problems. The modern mimetic discretization technology developed in part by the Authors allows one to solve these equations on unstructured polygonal, polyhedral and generalized polyhedral meshes. The book provides a practical guide for those scientists and engineers that are interested in the computational properties of the mimetic finite difference method such as the accuracy, stability, robustness, and efficiency. Many examples are provided to help the reader to understand and implement this method. This monograph also provides the essential background material and describes basic mathematical tools required to develop further the mimetic discretization technology and to extend it to various applications.

  3. Controller Synthesis for Robust Invariance of Polynomial Dynamical Systems using Linear Programming

    CERN Document Server

    Sassi, Mohamed Amin Ben

    2011-01-01

    In this paper, we consider a control synthesis problem for a class of polynomial dynamical systems subject to bounded disturbances and with input constraints. More precisely, we aim at synthesizing at the same time a controller and an invariant set for the controlled system under all admissible disturbances. We propose a computational method to solve this problem. Given a candidate polyhedral invariant, we show that controller synthesis can be formulated as an optimization problem involving polynomial cost functions over bounded polytopes for which effective linear programming relaxations can be obtained. Then, we propose an iterative approach to compute the controller and the polyhedral invariant at once. Each iteration of the approach mainly consists in solving two linear programs (one for the controller and one for the invariant) and is thus computationally tractable. Finally, we show with several examples the usefulness of our method in applications.

  4. Lattice engineering through nanoparticle-DNA frameworks

    Science.gov (United States)

    Tian, Ye; Zhang, Yugang; Wang, Tong; Xin, Huolin L.; Li, Huilin; Gang, Oleg

    2016-06-01

    Advances in self-assembly over the past decade have demonstrated that nano- and microscale particles can be organized into a large diversity of ordered three-dimensional (3D) lattices. However, the ability to generate different desired lattice types from the same set of particles remains challenging. Here, we show that nanoparticles can be assembled into crystalline and open 3D frameworks by connecting them through designed DNA-based polyhedral frames. The geometrical shapes of the frames, combined with the DNA-assisted binding properties of their vertices, facilitate the well-defined topological connections between particles in accordance with frame geometry. With this strategy, different crystallographic lattices using the same particles can be assembled by introduction of the corresponding DNA polyhedral frames. This approach should facilitate the rational assembly of nanoscale lattices through the design of the unit cell.

  5. Effect of surface cold work on corrosion of Alloy 690TT in high temperature high pressure water

    International Nuclear Information System (INIS)

    This paper aims to investigate the effect of surface cold work on corrosion of Alloy 690TT. The Alloy 690TT was mechanical ground and electro polished respectively and immersed in primary water at DO = 2 ppm and DH = 2.5ppm respectively. The microstructure of surface and the compositions and morphology of the surface film on Alloy 690TT after immersion test were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and focused ion beam (FIB). The results showed that feather-like oxide with decorated polyhedral oxide formed on ground surface and needle-like oxide with decorated polyhedral oxide formed on electro-polished surface. (author)

  6. Optimal panel-clustering in the presence of anisotropic mesh refinement

    OpenAIRE

    Graham, I.G.; Grasedyck, L; Hackbusch, W.; Sauter, S.

    2008-01-01

    In this paper we consider the numerical solution of discrete boundary integral equations on polyhedral surfaces in three dimensions. When the solution contains typical edge singularities, highly stretched meshes are preferred to uniform meshes, since they reduce the number of degrees of freedom needed to obtain a fixed accuracy. The classical panel-clustering method can still be applied in the presence of such highly stretched meshes. However, we will show that the savings in computation time...

  7. Synthesis and characterization of a POSS-maleimide precursor for hybrid nanocomposites

    OpenAIRE

    Jothibasu, S; S. Premkumar; Alagar, M.; Hamerton, I

    2008-01-01

    Epoxy polyhedral oligomeric silsesquioxane (POSS)-based hybrid nanocomposites were prepared by in situ polymerization of a homogeneous blend of the diglycidylether of bisphenol-A and 4,4'diaminodiphenylmethane (DDM) in the presence of octa(maleimidophenyl)silsesquioxane. The reaction of a maleimido-functionalized POSS cube with the epoxy resin was studied by Fourier transform infrared analysis and the formation of nanocomposites was confirmed by wide-angle X-ray diffraction and scanning elect...

  8. Immunofluorescence microscopy of organized microtubule arrays in structurally stabilized meristematic plant cells

    OpenAIRE

    1981-01-01

    Cells were prepared for indirect immunofluorescence microscopy after paraformaldehyde fixation of multicellular root apices and brief incubation in cell wall-digesting enzymes. This allowed subsequent separation of the tissue into individual cells or short files of cells which were put onto coverslips coated with polylysine. Unlike spherical protoplasts made from living tissues, these preparations retain the same polyhedral shape as the cells from which they are derived. Cellular contents, in...

  9. How effective is graphene nanopore geometry on DNA sequencing?

    OpenAIRE

    Satarifard, Vahid; Foroutan, Masumeh; Ejtehadi, Mohammad Reza

    2015-01-01

    In this paper we investigate the effects of graphene nanopore geometry on homopolymer ssDNA pulling process through nanopore using steered molecular dynamic (SMD) simulations. Different graphene nanopores are examined including axially symmetric and asymmetric monolayer graphene nanopores as well as five layer graphene polyhedral crystals (GPC). The pulling force profile, moving fashion of ssDNA, work done in irreversible DNA pulling and orientations of DNA bases near the nanopore are assesse...

  10. Sub-Critical Closed String Field Theory in D Less Than 26

    OpenAIRE

    Kaku, Michio

    1993-01-01

    We construct the second quantized action for sub-critical closed string field theory with zero cosmological constant in dimensions $ 2 \\leq D < 26$, generalizing the non-polynomial closed string field theory action proposed by the author and the Kyoto and MIT groups for $D = 26$. The proof of gauge invariance is considerably complicated by the presence of the Liouville field $\\phi$ and the non-polynomial nature of the action. However, we explicitly show that the polyhedral vertex functions ob...

  11. Synergistic photothermal ablative effects of functionalizing carbon nanotubes with a POSS-PCU nanocomposite polymer

    OpenAIRE

    Tan Aaron; Madani Seyed; Rajadas Jayakumar; Pastorin Giorgia; Seifalian Alexander M

    2012-01-01

    Abstract Background The application of nanotechnology in biology and medicine represents a significant paradigm shift in the approach to the treatment of cancer. Evidence suggests that when exposed to near-infrared radiation (NIR), carbon nanotubes (CNTs) dissipate a substantial amount of heat energy. We have developed a novel nanocomposite polymer, polyhedral oligomeric silsesquioxane poly (carbonate-urea) urethane (POSS-PCU). POSS-PCU displays excellent biocompatibility and has been used in...

  12. Design and development of a prosthetic implant for cardiovascular reconstructions

    OpenAIRE

    Ahmed, M.

    2011-01-01

    There is a significant worldwide demand for a small calibre vascular graft for use as a bypass or replacement conduit. Our lab has developed a novel nanocomposite poly- mer based on polyhedral oligomeric silsesquioxane and poly(carbonate-urea)urethane (POSS-PCU) which has displayed promising properties in vitro. In this thesis, POSS- PCU has been utilised to fabricate prosthetic small calibre conduits for use as arterial replacements. An important feature in determining the succes...

  13. A Nano-Inspired Multifunctional POSS-PCU Covered Stent: Endothelial Progenitor Cell Capture with Stealth Liposomal Drug Release

    OpenAIRE

    Tan, A. J. K.

    2014-01-01

    The 2 main unresolved issues inherent in coronary stents are in-stent restenosis (ISR) and late stent thrombosis (ST). ISR is largely due to vascular smooth muscle cell (VSMC) proliferation, and ST is attributed to a lack of re-endothelialization. This thesis describes the conceptualization and development of a biofunctionalized polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) platform, for the express purpose of circumventing ISR and ST. A bare-metal stent is emb...

  14. Surface modification of a POSS-nanocomposite material to enhance cellular integration of a synthetic bioscaffold

    OpenAIRE

    Crowley, C.; Klanrit, P; C.R. Butler; Varanou, A; Platé, M.; Hynds, R. E.; Chambers, R. C.; Seifalian, A. M.; Birchall, M A; Janes, S M

    2016-01-01

    Polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) is a versatile nanocomposite biomaterial with growing applications as a bioscaffold for tissue engineering. Integration of synthetic implants with host tissue can be problematic but could be improved by topographical modifications. We describe optimization of POSS-PCU by dispersion of porogens (sodium bicarbonate (NaHCO3), sodium chloride (NaCl) and sucrose) onto the material surface, with the principle aim of incre...

  15. Optimization of Acrylic Acid Grafting onto POSS-PCU Nanocomposite Using Response Surface Methodology

    OpenAIRE

    Solouk, A.; Solati-Hashjin, M.; S. Najarian; Mirzadeh, H.; Seifalian, A. M.

    2011-01-01

    The novel nanocomposite based on poly(carbonate-urea)urethane and polyhedral oligomeric silsesquioxanes (POSS) has been used in medicine especially in cardiovascular applications. It is also known that the cell affinity towards biomaterials can be promoted by immobilization of extracellular matrix proteins onto these materials surfaces. The inert surface of POSS-PCU nanocomposite is not directly suitable for immobilization of such biomolecules and therefore, its biocompatibility should be imp...

  16. Effects of sterilization treatments on bulk and surface properties of nanocomposite biomaterials

    OpenAIRE

    Ahmed, Maqsood; Punshon, Geoffrey; Darbyshire, Arnold; Seifalian, Alexander M

    2013-01-01

    With the continuous and expanding use of implantable biomaterials in a clinical setting, this study aims to elucidate the influence of sterilization techniques on the material surface and bulk properties of two polyurethane nanocomposite biomaterials. Both solid samples and porous membranes of nondegradable polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) and a biodegradable poly(caprolactone-urea) urethane (POSS-PCL) were examined. Sterilization techniques includ...

  17. Parallel Vertex Approximate Gradient discretization of hybrid dimensional Darcy flow and transport in discrete fracture networks

    OpenAIRE

    Xing, Feng; Masson, Roland; Lopez, Simon

    2016-01-01

    This paper proposes a parallel numerical algorithm to simulate the flow and the transport in a discrete fracture network taking into account the mass exchanges with the surrounding matrix. The discretization of the Darcy fluxes is based on the Vertex Approximate Gradient finite volume scheme adapted to polyhedral meshes and to heterogeneous anisotropic media, and the transport equation is discretized by a first order upwind scheme combined with an Euler explicit integration in time. The paral...

  18. The mathematics of lecture hall partitions

    OpenAIRE

    Savage, Carla D.

    2016-01-01

    Over the past twenty years, lecture hall partitions have emerged as fundamental combinatorial structures, leading to new generalizations and interpretations of classical theorems and new results. In recent years, geometric approaches to lecture hall partitions have used polyhedral geometry to discover further properties of these rich combinatorial objects. In this paper we give an overview of some of the surprising connections that have surfaced in the process of trying to understand the lect...

  19. Local bilinear multiple-output quantile/depth regression

    OpenAIRE

    Hallin, Marc; Lu, Zudi; Paindaveine, Davy; Šiman, Miroslav

    2015-01-01

    A new quantile regression concept, based on a directional version of Koenker and Bassett’s traditional single-output one, has been introduced in [ Ann. Statist. (2010) 38 635–669] for multiple-output location/linear regression problems. The polyhedral contours provided by the empirical counterpart of that concept, however, cannot adapt to unknown nonlinear and/or heteroskedastic dependencies. This paper therefore introduces local constant and local linear (actually, bilinear) versions o...

  20. Local Constant and Local Bilinear Multiple-Output Quantile Regression

    OpenAIRE

    Hallin, Marc; Lu, Zudi; Paindaveine, Davy; Siman, Miroslav

    2012-01-01

    A new quantile regression concept, based on a directional version of Koenker and Bassett’s traditional single-output one, has been introduced in [Hallin, Paindaveine and ˇSiman, Annals of Statistics 2010, 635-703] for multiple-output regression problems. The polyhedral contours provided by the empirical counterpart of that concept, however, cannot adapt to nonlinear and/or heteroskedastic dependencies. This paper therefore introduces local constant and local linear versio...

  1. Controlling the alignment of liquid crystals by nanoparticle-doped and UV-treated polyimide alignment films

    Science.gov (United States)

    Jeng, Shie-Chang; Hwang, Su-June; Chen, Tai-An; Liu, Han-Shiang; Chen, Mu-Zhe

    2012-03-01

    We have developed two approaches for controlling the pretilt angles of liquid crystal molecules by using conventional polyimide (PI) alignment materials either doping homogeneous PIs with Polyhedral Oligomeric Silsequioxanes (POSS) nanoparticles or treating homeotropic PIs with ultraviolet light. These techniques are very simple and are compatible with current methods familiar in the LCD industry. The characteristics of modified PI alignment films and their applications for photonic devices are demonstrated in this paper.

  2. The dynamic behaviour of a modified polyurethane resin

    OpenAIRE

    Appleby-Thomas, G. J.; Hazell, P.J.; Stennett, C; Cooper, G; Cleave, R.

    2011-01-01

    The dynamic response of both a pure and nano-reinforced polyurethane replacement resin (PRR) have been investigated using plate impact techniques. Similar U-P-U- S Hugoniot equations of state have been established for both materials, despite the altered cross-linking associated with the addition of inorganic polyhedral oligomeric silsesquioxane (POSS) blocks of c. 1.5 nm size to the resin matrix. At higher particle velocities a similar U-P-U-S response to that of polyurethane ...

  3. Enhanced Formulations for Minimax and Discrete Optimization Problems with Applications to Scheduling and Routing

    OpenAIRE

    Ghoniem, Ahmed

    2007-01-01

    This dissertation addresses the development of enhanced formulations for minimax and mixed-integer programming models for certain industrial and logistical systems, along with the design and implementation of efficient algorithmic strategies. We first examine the general class of minimax mixed-integer 0-1 problems of the type that frequently arise in decomposition approaches and in a variety of location and scheduling problems. We conduct an extensive polyhedral analysis of this problem in o...

  4. Chemomechanical Origin of Hydrogen Trapping at Grain Boundaries in FCC Metals

    OpenAIRE

    Zhou, Xiao; Marchand, Daniel; McDowell, David L.; Zhu, Ting; Song, Jun

    2015-01-01

    Hydrogen embrittlement of metals is widely observed, but its atomistic origins remain little understood and much debated. Combining a unique identification of interstitial sites through polyhedral tessellation and first-principles calculations, we study hydrogen adsorption at grain boundaries in a variety of face-centered cubic metals of Ni, Cu, gamma-Fe and Pd. We discover the chemomechanical origin of variation of adsorption energetics for interstitial hydrogen at grain boundaries. A genera...

  5. Influence of rounds sub-grains in high burnup UO2 fuel

    International Nuclear Information System (INIS)

    In a recent paper, it has been shown that the so called 'rim structure' in high burnup UO2 fuel contains in fact two types of sub-grains: polyhedral and round ones. Polyhedral sub-grains have an average size of approximately 0.5 μm, and have been observed for more than ten years. The faceted porosity associated to these polyhedral sub-grains is characteristic of the rim effect. Round sub-grains have an average size of approximately 0.2 μm and are found to be formed on the free surface of initial grains or of polyhedral sub-grains. Round sub-grains can be observed in the rim area and also continuously from the periphery to the mid-pellet. This suggests that round sub-grains do not depend on rim effect, but are more likely to derive from a surface effect. In this contribution SEM photographs showing the evolution of the round sub-grains morphology will support a proposed mechanism for round sub-grains formation. This mechanism involves a surface modification due to stresses applied on a free surface using the Greenfeld formalism. These stresses could be due to segregation of fission products on some grain faces. This supposition is supported by EPMA experiments which show the segregation of some fission products on surfaces where round sub-grains are observed, while other surfaces with no round sub-grains have the same concentration in fission products as the bulk of the grains. Segregation of fission products on surface has also been observed in CANDU fuel by XPS. This specific behaviour of fission products gives a new insight in the chemistry of irradiated fuel and asks the question of the influence of round sub-grains formations on the release of fission products. (author)

  6. Face-Guarding Polyhedra

    OpenAIRE

    Viglietta, Giovanni

    2013-01-01

    We study the Art Gallery Problem for face guards in polyhedral environments. The problem can be informally stated as: how many (not necessarily convex) windows should we place on the external walls of a dark building, in order to completely illuminate its interior? We consider both closed and open face guards (i.e., faces with or without their boundary), and we study several classes of polyhedra, including orthogonal polyhedra, 4-oriented polyhedra, and 2-reflex orthostacks. We give upper and...

  7. Tracking Control in Billiards Using Mirrors without Smoke, Part II: Additional Lyapunov-Based Local and Global Results

    OpenAIRE

    Forni, Fulvio; Teel, Andrew

    2011-01-01

    Two control results are described: 1) local tracking control for convex billiards with piecewise locally Lipschitz boundary, and 2) global tracking control for special polyhedral billiards, including rectangles and equilateral triangles. The controllers are based on Lyapunov functions and a mirroring concept introduced in a companion paper. The local results require the impacts to satisfy an average dwell-time condition with parameters that depend on the Lipschitz constant of the function tha...

  8. DNA Cages with Icosahedral Symmetry in Bionanotechnology

    Science.gov (United States)

    Jonoska, Nataša; Taormina, Anne; Twarock, Reidun

    Blueprints for polyhedral cages with icosahedral symmetry made of circular DNA molecules are provided. The basic rule is that every edge of the cage is met twice in opposite directions by the DNA strand(s), and vertex junctions are realized by a set of admissible junction types. As nanocontainers for cargo storage and delivery, the icosidodecahedral cages are of special interest because they have the largest volume per surface ratio of all cages discussed here.

  9. Inverse parametric convex programming problems via convex liftings

    OpenAIRE

    Nguyen, Ngoc Anh; Olaru, Sorin; Rodriguez-Ayerbe, Pedro; Hovd, Morten; Necoara, Ion

    2014-01-01

    The present paper introduces a procedure to recover an inverse parametric linear or quadratic programming problem from a given liftable polyhedral partition over which a continuous piecewise affine function is defined. The solution to the resulting parametric linear problem is exactly the initial piecewise affine function over the given original parameter space partition. We provide sufficient conditions for the existence of solutions for such inverse problems. Furthermore, the constructive p...

  10. Towards a topological fingerprint of music

    OpenAIRE

    Bergomi, Mattia G.; Baraté, Adriano; Di Fabio, Barbara

    2016-01-01

    Can music be represented as a meaningful geometric and topological object? In this paper, we propose a strategy to describe some music features as a polyhedral surface obtained by a simplicial interpretation of the \\textit{Tonnetz}. The \\textit{Tonnetz} is a graph largely used in computational musicology to describe the harmonic relationships of notes in equal tuning. In particular, we use persistent homology in order to describe the \\textit{persistent} properties of music encoded in the afor...

  11. Probabilistic structural analysis by extremum methods

    Science.gov (United States)

    Nafday, Avinash M.

    1990-01-01

    The objective is to demonstrate discrete extremum methods of structural analysis as a tool for structural system reliability evaluation. Specifically, linear and multiobjective linear programming models for analysis of rigid plastic frames under proportional and multiparametric loadings, respectively, are considered. Kinematic and static approaches for analysis form a primal-dual pair in each of these models and have a polyhedral format. Duality relations link extreme points and hyperplanes of these polyhedra and lead naturally to dual methods for system reliability evaluation.

  12. Recent Contributions and Modem Perspectives in XRD Studies of Minerals

    OpenAIRE

    Pushcharovsky, Dmitry Yu.

    2000-01-01

    Some exciting recent developments in the field of mineralogical crystallography are considered. The crystal Chemical phenomena (e.g. ionic ordering, polyhedral stacking variations, microtwinning, modulation), which accompany the formation of real structures, are discussed on the basis of structural studies of a large group of minerals, recently investigated in the Moscow State University. The new approaches used for their investigation allowed extending the Scientific ideas connected with: th...

  13. Effects of melt blended poss nanofillers on pom and ABS thermal stability

    OpenAIRE

    Vilà Ramírez, Narciso

    2014-01-01

    This PhD thesis investigated the incorporation of Polyhedral Oligomeric Silsesquioxanes (POSS) in thermoplastic base materials via melt-blending procedures. Particularly, a focus is taken on the enhancement of the thermal resistance through the addition of different types of POSS on two popular engineering plastics known by their low thermal stability, one being a semi-crystalline copolymer i.e. polyoxymethylene (POM) and the other an amorphous copolymer i.e. acrylonitrile butadiene styren...

  14. Parent’s perception about motor-sport activity in Italian primary school

    OpenAIRE

    Gomez-Paloma, Filippo; Agrillo, Filomena; D'anna, Cristiana

    2013-01-01

    The educational value of motor-sport activity in Italia Primary School had its full acknowledgement through a historical development that has seen the legislative evolution and scientific research to carry on together. This increase has inevitably conditioned the school that had to adapt its educational proposals to the new cultural changes. The child with his needs and his personal needs becomes the pivot around which all educational interventions. Participation in activities polyhedral inve...

  15. Columnar grain growth in non-oriented silicon steels

    International Nuclear Information System (INIS)

    By modifying the temperature course of the decarbonising annealing in the final processing of the electrical steels in laboratory and operational conditions, a material with a columnar structure has been prepared. The formation process of this structure was controlled by carbon diffusion. From the point of view of magnetic properties, the columnar structure presents a more advantageous texture than the inhomogeneous polyhedral structure, produced by the classical method of decarbonising annealing. (author)

  16. Hybrid electrolytes with controlled network structures for lithium metal batteries.

    Science.gov (United States)

    Pan, Qiwei; Smith, Derrick M; Qi, Hao; Wang, Shijun; Li, Christopher Y

    2015-10-21

    Solid polymer electrolytes (SPEs) with tunable network structures are prepared by a facile one-pot reaction of polyhedral oligomeric silsesquioxane and poly(ethylene glycol). These SPEs, with high conductivity and high modulus, exhibit superior resistance to lithium dendrite growth even at high current densities. Measurements of lithium metal batteries with a LiFePO4 cathode show excellent cycling stability and rate capability. PMID:26316140

  17. Mesoporous Silicon with Modified Surface for Plant Viruses and Their Protein Particle Sensing

    OpenAIRE

    Kae Dal Kwack; Jung Young Son; Yuriy Vashpanov

    2008-01-01

    Changes in electric parameters of a mesoporous silicon treated by a plasma chemical etching with fluorine and hydrogen ions, under the adsorption of NEPO (Nematodetransmitted Polyhedral) plant viruses such as TORSV (Tomato Ringspot Virus), GFLV (Grapevine Fan Leaf Virus) and protein macromolecule from TORSV particles are described. The current response to the applied voltage is measured for each virus particle to investigate the material parameters which are sensitive to the adsorbed particle...

  18. Research on Spacecraft Illumination

    OpenAIRE

    Bo Cai; Ling Li; Jing Hu; Biao He; Yuan Long; Dengyi Zhang

    2011-01-01

    Illumination analysis of spacecraft is very important. This paper firstly introduces the importance of spacecraft illumination analysis in aerospace fields and points out that illumination conditions will influence the design of shape of spacecraft body and the installation of spacecraft equipments. Then, it discusses two methods for analyzing spacecraft solar-panel shadow and illumination conditions: ray tracing illumination algorithm and polyhedral mesh contour edge projection algorithm and...

  19. Granular cell tumor: An uncommon benign neoplasm

    Directory of Open Access Journals (Sweden)

    Tirthankar Gayen

    2015-01-01

    Full Text Available Granular cell tumor is a distinctly rare neoplasm of neural sheath origin. It mainly presents as a solitary asymptomatic swelling in the oral cavity, skin, and rarely internal organs in the middle age. Histopathology is characteristic, showing polyhedral cells containing numerous fine eosinophilic granules with indistinct cell margins. We present a case of granular cell tumor on the back of a 48-year-old woman which was painful, mimicking an adnexal tumor.

  20. Two-Layer Planarization in Graph Drawing

    OpenAIRE

    Mutzel, Petra; Weiskircher, René

    1998-01-01

    We study the \\tlpp s that have applications in Automatic Graph Drawing. We are searching for a two-layer planar subgraph of maximum weight in a given two-layer graph. Depending on the number of layers in which the vertices can be permuted freely, that is, zero, one or two, different versions of the problems arise. The latter problem was already investigated in \\cite{Mut97} using polyhedral combinatorics. Here, we study the remaining two cases and the relationships bet...

  1. ISAM - an Interactive Service for Asteroid Models

    Science.gov (United States)

    Bartczak, P.; Marciniak, A.

    2011-10-01

    We present an interactive web service for past and future physical ephemeris of polyhedral asteroid shape models obtained mainly with the lightcurve inversion method. Our tool allows for plane-of-sky views of the models, that can be then compared with asteroid images obtained using different techniques like occultations, radar or thermal infrared. Additionally, lightcurves, animated views, and stereoscopic images can be generated by the users. The service is available at the address: http://isam.astro.amu.edu.pl

  2. Productive replication of Malacosoma neustria nucleopolyhedrovirus (ManeNPV) in Md203 cell line

    OpenAIRE

    DEMİR, İsmail; GÜREL, Nurten; NALÇACIOĞLU, Remziye; İNCE, İkbal A.; DEMİRBAĞ, Zihni

    2009-01-01

    A plaque-purified genotypic variant, derived from a field isolate of the Malacosoma neustria nucleopolyhedrovirus (ManeNPV) from Turkey was characterized based on in vitro replication properties in a cell line, Md203 derived from Malacosoma disstria. The life cycle of ManeNPV was studied based on the cytopathic effects (CPEs), polyhedral inclusion body (PIB) formation, budded virus (BV) production, viral DNA replication and polyhedrin protein expression in ManeNPV-infected Md203 cells. Infec...

  3. Stabilization of fuzzy systems with constrained controls by using positively invariant sets

    Directory of Open Access Journals (Sweden)

    A. El Hajjaji

    2006-01-01

    Full Text Available We deal with the extension of the positive invariance approach to nonlinear systems modeled by Takagi-Sugeno fuzzy systems. The saturations on the control are taken into account during the design phase. Sufficient conditions of asymptotic stability are given ensuring at the same time that the control is always admissible inside the corresponding polyhedral set. Both a common Lyapunov function and piecewise Lyapunov function are used.

  4. Coated vesicles participate in the receptor-mediated endocytosis of insulin

    OpenAIRE

    1983-01-01

    We have purified coated vesicles from rat liver by differential ultracentrifugation. Electron micrographs of these preparations reveal only the polyhedral structures typical of coated vesicles. SDS PAGE of the coated vesicle preparation followed by Coomassie Blue staining of proteins reveals a protein composition also typical of coated vesicles. We determined that these rat liver coated vesicles possess a latent insulin binding capability. That is, little if any specific binding of 125I-insul...

  5. Hybrid Atlas Models

    CERN Document Server

    Ichiba, Tomoyuki; Banner, Adrian; Karatzas, Ioannis; Fernholz, Robert

    2009-01-01

    We study Atlas-type models of equity markets with local characteristics that depend on both name and rank, and in ways that induce a stability of the capital distribution. Ergodic properties and rankings of processes are examined with reference to the theory of reflected Brownian motions in polyhedral domains. In the context of such models, we discuss properties of various investment strategies, including the so-called growth-optimal and universal portfolios.

  6. Chondrogenic potential of bone marrow-derived mesenchymal stem cells on a novel, auricular-shaped, nanocomposite scaffold.

    OpenAIRE

    Patel, K H; Nayyer, L.; Seifalian, A. M.

    2013-01-01

    Reconstruction of the human auricle remains a challenge to plastic surgeons, and current approaches are not ideal. Tissue engineering provides a promising alternative. This study aims to evaluate the chondrogenic potential of bone marrow–derived mesenchymal stem cells on a novel, auricular-shaped polymer. The proposed polyhedral oligomeric silsesquioxane-modified poly(hexanolactone/carbonate)urethane/urea nanocomposite polymer has already been transplanted in patients as the world’s first syn...

  7. Studies of the Crystallization Process of Aluminum-Silicon Alloys Using a High Temperature Microscope. Thesis

    Science.gov (United States)

    Justi, S.

    1985-01-01

    It is shown that primary silicon crystals grow polyhedral in super-eutectic AlSi melts and that phosphorus additives to the melt confirm the strong seeding capacity. Primary silicon exhibits strong dendritic seeding effects in eutectic silicon phases of various silicon alloys, whereas primary aluminum does not possess this capacity. Sodium addition also produces a dendritic silicon network growth in the interior of the sample that is attributed to the slower silicon diffusion velocity during cooling.

  8. Golden Root Geometry Structuring the Polyhedra and Other Forms Via Plato’s Triangles

    OpenAIRE

    Panagiotis Chr. Stefanides

    2014-01-01

    Under Golden Root Geometry Structuring the Polyhedra and other Forms Via Plato’s Triangles, we refer to the basic geometric configurations which, as this theory contemplates, are necessary for the progressive mode of formation of the five polyhedral and the geometries involved in their sections and related circles and further to logarithms, via lines, areas and volumes. Basis of all these structures is a very special Scalene Orthogonal Triangle “Plato’s Most Beautiful”...

  9. Multiple optimal solutions to a sort of nonlinear optimization problem

    Institute of Scientific and Technical Information of China (English)

    Xue Shengjia

    2007-01-01

    The optimization problem is considered in which the objective function is pseudolinear(both pseudoconvex and pseudoconcave) and the constraints are linear. The general expression for the optimal solutions to the problem is derived with the representation theorem of polyhedral sets, and the uniqueness condition of the optimal solution and the computational procedures to determine all optimal solutions ( ifthe uniqueness condition is not satisfied ) are provided. Finally, an illustrative example is also given.

  10. An Efficient Inexact ABCD Method for Least Squares Semidefinite Programming

    OpenAIRE

    Sun, Defeng; Toh, Kim-Chuan; Yang, Liuqin

    2015-01-01

    We consider least squares semidefinite programming (LSSDP) where the primal matrix variable must satisfy given linear equality and inequality constraints, and must also lie in the intersection of the cone of symmetric positive semidefinite matrices and a simple polyhedral set. We propose an inexact accelerated block coordinate descent (ABCD) method for solving LSSDP via its dual, which can be reformulated as a convex composite minimization problem whose objective is the sum of a coupled quadr...

  11. Neopolares de problemas de empaquetamiento sobre semigrupos

    OpenAIRE

    Aráoz Durand, Julián Arturo

    1982-01-01

    Los neopolares permiten caracterizar las caras de un poliedro combinatorio como vértices de poliedros altamente estructurados. Esto sirve para generar planos de cortes y para obtener propiedades duales en problemas de programación entera. Gomory caracterizó neopolares para problemas sobre grupos, Aráoz en "Polyhedral Neopolarities" extendió estos resultados a semigrupos de cubrimiento. En este trabajo se caracterizan neopolares importantes de semigrupos de empaquetamiento que incluyen los pro...

  12. Fanovarietäten mit Toruswirkung der Komplexität Eins

    OpenAIRE

    Huggenberger, Elaine

    2013-01-01

    The subject of this thesis are varieties with a torus action of complexity one, i.e. algebraic varieties X with an algebraic torus T acting effectively on them, where dim(T)=dim(X)-1. A combinatorial description for such varieties is provided which generalizes the convex geometrical description of toric varieties by lattice fans. The systematical construction of rational complexity-one T-varieties in terms of certain integral matrices and a collection of polyhedral cones is applied to classi...

  13. Differential protein partitioning within the herpesvirus tegument and envelope underlies a complex and variable virion architecture

    OpenAIRE

    Bohannon, Kevin Patrick; Jun, Yonggun; Gross, Steven P.; Smith, Gregory Allan

    2013-01-01

    Neuroinvasive herpesviruses cause diseases in humans ranging from cold sores to central nervous system infections. Unlike most icosahedral viruses, herpesvirus capsids are surrounded by protein layers that lack polyhedral architecture. The outer layers are critical for herpesvirus infectivity. Although the disorganized layers are visible by electron microscopy, the protein topography of these layers remains unclear. We fused fluorophores to virus proteins and pinpointed their positions within...

  14. Software for Exact Integration of Polynomials over Polyhedra

    CERN Document Server

    De Loera, Jesus; Koeppe, Matthias; Moreinis, Stanislav; Pinto, Gregory; Wu, Jianqiu

    2011-01-01

    We are interested in the fast computation of the exact value of integrals of polynomial functions over convex polyhedra. We present speed ups and extensions of the algorithms presented in previous work. We present the new software implementation and provide benchmark computations. The computation of integrals of polynomials over polyhedral regions has many applications; here we demonstrate our algorithmic tools solving a challenge from combinatorial voting theory.

  15. Granular Cell Tumor: An Uncommon Benign Neoplasm

    OpenAIRE

    Tirthankar Gayen; Anupam Das; Kaushik Shome; Debabrata Bandyopadhyay; Dipti Das; Abanti Saha

    2015-01-01

    Granular cell tumor is a distinctly rare neoplasm of neural sheath origin. It mainly presents as a solitary asymptomatic swelling in the oral cavity, skin, and rarely internal organs in the middle age. Histopathology is characteristic, showing polyhedral cells containing numerous fine eosinophilic granules with indistinct cell margins. We present a case of granular cell tumor on the back of a 48-year-old woman which was painful, mimicking an adnexal tumor.

  16. CHEMICAL REACTIONS AT NANOMETAL PARTICLES

    OpenAIRE

    GALO CÁRDENAS-TRIVIÑO

    2005-01-01

    The concept of nanochemistry and the reactions involved are discussed. The work is focused on nanoparticles obtained from colloidal dispersions. The colloidal particles by transmission electron microscopy of low and high resolution were analyzed. The high resolution electron miscroscopy (HRTEM) allow us to classify the nanostructure of the metal particles in some polyhedral models: cubooctahedron, truncated octahedron, tetracai decahedron and icosahedron. Some HRTEM of Pd-2 propanol and Ge-2-...

  17. Active Polyhedron: Surface Evolution Theory Applied to Deformable Meshes

    OpenAIRE

    Slabaugh, G. G.; Unal, G.B.

    2005-01-01

    This paper presents a novel 3D deformable surface that we call an active polyhedron. Rooted in surface evolution theory, an active polyhedron is a polyhedral surface whose vertices deform to minimize a regional and/or boundarybased energy functional. Unlike continuous active surface models, the vertex motion of an active polyhedron is computed by integrating speed terms over polygonal faces of the surface. The resulting ordinary differential equations (ODEs) provide improved robustness to noi...

  18. Matching and Clustering: Two Steps Towards Automatic Model Generation in Computer Vision

    OpenAIRE

    Gros, Patrick

    1993-01-01

    International audience In this paper, we present a general frame for a system of automatic modelling and recognition of 3D polyhedral objects. Such a system has many applications for robotics : recognition, localization, grasping,...Here we focus upon one main aspect of the system : when many images of one 3D object are taken from different unknown viewpoints, how to recognize those of them which represent the same aspect of the object ? Briefly, it is possible to determine automatically i...

  19. Mathematical Programming Decoding of Binary Linear Codes: Theory and Algorithms

    OpenAIRE

    Helmling, Michael; Ruzika, Stefan; Tanatmis, Akin

    2011-01-01

    Mathematical programming is a branch of applied mathematics and has recently been used to derive new decoding approaches, challenging established but often heuristic algorithms based on iterative message passing. Concepts from mathematical programming used in the context of decoding include linear, integer, and nonlinear programming, network flows, notions of duality as well as matroid and polyhedral theory. This survey article reviews and categorizes decoding methods based on mathematical pr...

  20. Multifunctional photoreactive inorganic cages for three-dimensional holographic data storage.

    Science.gov (United States)

    Lee, Seungwoo; Jeong, Yong-Cheol; Lee, Jihye; Park, Jung-Ki

    2009-10-15

    We demonstrate a holographic photopolymer based on multifunctional photoreactive inorganic cages, polyhedral oligomeric silsesquioxane (POSS). It is shown that a second photopolymerizable monomer, POSS, for the photopolymer, contributes to significantly enhance photosensitivity as well as refractive index modulation (Deltan). We also found that during the formation of holographic gratings, polymerization of POSS could effectively suppress volume shrinkage of photopolymer resin, owing to its filler-strengthening effect of inorganic cages accompanied with interpenetrating effect. PMID:19838237

  1. A compactification of the Bruhat-Tits building

    CERN Document Server

    Landvogt, Erasmus

    1996-01-01

    The aim of this work is the definition of the polyhedral compactification of the Bruhat-Tits building of a reductive group over a local field. In addition, an explicit description of the boundary is given. In order to make this work as self-contained as possible and also accessible to non-experts in Bruhat-Tits theory, the construction of the Bruhat-Tits building itself is given completely.

  2. CFD Analysis on the Main-Rotor  Blade ofa Scale Helicopter  Model using Overset Meshing

    OpenAIRE

    Rodriguez, Christian

    2012-01-01

    In this paper, an analysis in computational uid dynamics (CFD) is presented on a helicopter scale model with focus on the main-rotor blades.The helicopter model is encapsulated in a background region and the ow eld is solved using Star CCM+. A surface and volume mesh continuum was generated that contained approximately seven million polyhedral cells, where the Finite Volume Method (FVM) was chosen as a discretization technique. Each blade was assigned to an overset region making it possible t...

  3. ON ALTERNATIVE OPTIMAL SOLUTIONS TO QUASIMONOTONIC PROGRAMMING WITH LINEAR CONSTRAINTS

    Institute of Scientific and Technical Information of China (English)

    Xue Shengjia

    2007-01-01

    In this paper, the nonlinear programming problem with quasimonotonic ( both quasiconvex and quasiconcave )objective function and linear constraints is considered. With the decomposition theorem of polyhedral sets, the structure of optimal solution set for the programming problem is depicted. Based on a simplified version of the convex simplex method,the uniqueness condition of optimal solution and the computational procedures to determine all optimal solutions are given, if the uniqueness condition is not satisfied. An illustrative example is also presented.

  4. CFD Analysis of in-Cylinder Flow and Air-Fuel Interaction on Different Combustion Chamber Geometry in DISI Engine

    OpenAIRE

    B. Harshavardhan; Mallikarjuna, J. M.

    2013-01-01

    In this investigation, a CFD analysis has been carried out on in-cylinder fluid flows and air-fuel interaction in Direct Injection Spark Ignition (DISI) engine by changing combustion chamber geometry during intake and compression stroke at an engine speed of 1500 rpm for four different types of piston profiles viz., flat piston, flat piston with centre bowl, dome piston with centre bowl and pentroof offset bowl piston. A polyhedral trimmed cell has been taken for meshing of the geometries usi...

  5. The Structure of the Set of Equilibria for Two Person Multicriteria Games

    OpenAIRE

    Borm, P.E.M.; Vermeulen, D.; Voorneveld, M.

    1998-01-01

    In this paper the structure of the set of equilibria for two person multicriteria games is analysed. It turns out that the classical result for the set of equilibria for bimatrix games, that it is a finite union of polytopes, is only valid for multicriteria games if one of the players only has two pure strategies. A full polyhedral description of these polytopes can be derived when the player with an arbitrary number of pure strategies has one criterion.

  6. Photoelectron Spectroscopy Study of [Ta2B6]-: a Hexagonal Bipyramdial Cluster

    Science.gov (United States)

    Jian, Tian; Li, Weili; Romanescu, Constantin; Wang, Lai-Sheng

    2014-06-01

    It has been a long-sought goal in cluster science to discover stable atomic clusters as building blocks for cluster-assembled nanomaterials, as exemplified by the fullerenes and their subsequent bulk syntheses.[1,2] Clusters have also been considered as models to understand bulk properties, providing a bridge between molecular and solid-state chemistry.[3] Herein we report a joint photoelectron spectroscopy and theoretical study on the [Ta2B6]- and [Ta2B6] clusters.[4] The photoelectron spectrum of [Ta2B6]- displays a simple spectral pattern and a large HOMO-LUMO gap, suggesting its high symmetry. Theoretical calculations show that both the neutral and anion are D6h pyramidal. The chemical bonding analyses for [Ta2B6] revealed the nature of the B6 and Ta interactions and uncovered strong covalent bonding between B6 and Ta. The D6h-[TaB6Ta] gaseous cluster is reminiscent of the structural pattern in the ReB6X6Re core in the [(Cp*Re)2B6H4Cl2] and the TiB6Ti motif in the newly synthesized Ti7Rh4Ir2B8 solid-state compound.[5,6] The current work provides an intrinsic link between a gaseous cluster and motifs for solid materials. Continued investigations of the transition-metal boron clusters may lead to the discovery of new structural motifs involving pure boron clusters for the design of novel boride materials. Reference [1] H.W. Kroto, J. R. Heath, S. C. OBrien, R. F. Curl, R. E. Smalley, Nature 1985, 318, 162 - 163. [2] W. Krtschmer, L. D. Lamb, K. Fostiropoulos, D. R. Huffman, Nature 1990, 347, 354 - 358. [3] T. P. Fehlner, J.-F. Halet, J.-Y. Saillard, Molecular Clusters: A Bridge to Solid-State Chemitry, Cambridge University Press, UK, 2007. [4] W. L. Li, L. Xie, T. Jian, C. Romanescu, X. Huang, L.-S. Wang, Angew. Chem. Int. Ed. 2014, 126, 1312 - 1316. [5] B. Le Guennic, H. Jiao, S. Kahlal, J.-Y. Saillard, J.-F. Halet, S. Ghosh, M. Shang, A. M. Beatty, A. L. Rheingold, T. P. Fehlner, J. Am. Chem. Soc. 2004, 126, 3203 - 3217. [6] B. P. T. Fokwa, M. Hermus, Angew

  7. Electron wavepacket dynamics in highly quasi-degenerate coupled electronic states: A theory for chemistry where the notion of adiabatic potential energy surface loses the sense

    Science.gov (United States)

    Yonehara, Takehiro; Takatsuka, Kazuo

    2012-12-01

    electron wavepacket dynamics in path-branching representation and the so-called semiclassical Ehrenfest theory to a hydrogen molecule embedded in twelve membered boron cluster (B12) in excited states, which are densely quasi-degenerate due to the vacancy in 2p orbitals of boron atom [1s22s22p1]. Bond dissociation of the hydrogen molecule quickly takes place in the cluster and the resultant hydrogen atoms are squeezed out to the surface of the cluster. We further study collision dynamics between H2 and B12, which also gives interesting phenomena. The present study suggests an interesting functionality of the boron clusters.

  8. Influence of surface roughness on the corrosion behavior of Alloy 690TT in PWR primary water

    International Nuclear Information System (INIS)

    Highlights: • Surface roughness effect on the corrosion rate of Alloy 690 is provided. • Surface micro-hardness decreased as the roughness value decreased. • Cr-enriched polyhedral oxide particles were formed on the ground surfaces. • Ni-enriched strip-like oxides were formed on the polished surfaces. • Corrosion rate decreased with a decrease in the roughness value. - Abstract: The purpose of this work is to investigate the effect of surface roughness on the corrosion behavior of Alloy 690TT steam generator tube material in simulated primary water at 330 °C. The surface roughness was controlled in the range of 710–25 nm by mechanical grinding and polishing method. Surface hardness gradually decreased with a decrease in the roughness value. Polyhedral oxide particles were formed on the ground surfaces, whereas the mixed oxides of a polyhedral and strip-like type were observed on the polished surface. The corrosion rate decreased by about 64% as the roughness values decreased from 710 to 150 nm. However, no further changes were observed in the range of 150–25 nm

  9. High-temperature borate liquids: physical properties of glass-forming compositions

    Energy Technology Data Exchange (ETDEWEB)

    Riebling, E.F.

    1977-05-06

    Several experimental routes can be used to develop a better understanding of the polymeric constitution (polyanionic and/or polyhedral distribution) of borate, germanate, and silicate glasses. Spectral, chemical, physical-chemical, and mechanical property information can be determined directly for the glass compositions of interest. Generally, only physical-chemical information is readily accessible for the corresponding high temperature liquids. It will be shown that information on each state of matter has its own particular merits. Most of the evidence thus far published suggests an excellent agreement between polyhedral distributions in an oxide glass and its corresponding high temperature liquid state. There is no well known oxide glass forming system for which such a state of affairs does not exist. In spite of this, occasional efforts are put forth which ignore some of what is known for oxide liquids, glasses, and crystals. Such attempts therefore invariably imply, if only indirectly, that significant changes occur in the polyhedral distributions close to the glass transition temperature region. Specific examples to be discussed will include efforts that avoid well known coordination change equilibria such as BO/sub 3/ reversible BO/sub 4/ and GeO/sub 4/ reversible GeO/sub 6/.

  10. A Novel Virtual Node Hexahedral Element with Exact Integration and Octree Meshing

    Directory of Open Access Journals (Sweden)

    Logah Perumal

    2016-01-01

    Full Text Available The method presented in this work is a 3-dimensional polyhedral finite element (3D PFEM based on virtual node method. Novel virtual node polyhedral elements (termed as VPHE are developed here, particularly virtual node hexahedral element (termed as VHE. Stiffness matrices of these polyhedral elements consist of simple polynomials. Thus, a new algorithm is introduced in this paper, which enables exact integration of monomials without a need for high number of integration points and weights. The number of nodes for VHE elements is not restricted, as opposed to the conventional hexahedral elements. This feature enables formulation of transition elements (termed as T-VHE which are useful to adaptive computation. Performances of the new VHE elements in solid mechanics and conductive heat transfer phenomena are examined through numerical simulations. The new T-VHE elements are utilized in octree mesh. The VHE elements are found to produce good results and T-VHE elements help to reduce number of global nodes for the analysis.

  11. Leiomyosarcoma with partial rhabdomyoblastic differentiation: First case report of primary cardiac origin

    Directory of Open Access Journals (Sweden)

    Hiruta Nobuyuki

    2011-02-01

    Full Text Available Abstract Background Leiomyosarcoma occurring as a primary cardiac tumor has been known as an extremely rare condition. Previous studies of leiomyosarcoma with rhabdomyoblastic differentiation have conducted to those arisen from another site, and they indicated a poorer prognosis of this tumor. Case presentation A 69-year-old woman was referred to our hospital for an operation concerning umbilical hernia. Subsequent imaging examinations before an operation indicated the presence of primary cardiac malignant tumor due to its atypical shape. And then, it was surgically removed. Histopathologically, tumor cells consisted of two different types: spindle and polyhedral cells. Immunohistochemically, it is interesting to note that 2.1% of spindle cells and 23.1% of polyhedral cells showed positive reactivity for myogenin. Furthermore, we performed double-immunostaining for alpha-smooth muscle actin (SMA and myogenin. The rates of alpha-SMA and myogenin double negative, alpha-SMA single positive, myogenin single positive, and alpha-SMA and myogenin double positive in spindle cells were estimated as 69.1%, 28.8%, 1.1% and 1.0%, respectively. In contrast, the rates in polyhedral cells were estimated as 76.9%, 0.0%, 23.1%, and 0.0%, respectively. Conclusion Our immunohistochemical evaluation suggested that rhabdomyoblastic differentiation in leiomyosarcoma might be generated not only by de novo generation from mesenchymal cells. To the best of our knowledge, this is the first case of primary cardiac leiomyosarcoma with partial rhabdomyoblastic differentiation.

  12. Reconstruction and Quantitative Characterization of Multiphase, Multiscale Three-Dimensional Microstructure of a Cast Al-Si Base Alloy

    Science.gov (United States)

    Singh, H.; Gokhale, A. M.; Mao, Y.; Tewari, A.; Sachdev, A. K.

    2009-12-01

    The serial sectioning technique is well known for the reconstruction of three-dimensional (3D) microstructures of opaque materials. In recent years, techniques also have been developed for the reconstruction of high-fidelity, large-volume segments of 3D microstructures that use montage serial sections and robot-assisted automated acquisitions of montage serial sections. This article reports the reconstruction of the multiphase, multiscale 3D microstructure of a permanent mold cast unmodified Al-12 wt pct Si-1 wt pct Ni base alloy that contains eutectic Si platelets, coarse primary polyhedral Si particles, Fe-rich script intermetallic particles, and pores. These constituents are segmented, reconstructed, rendered, and characterized in three dimensions. The estimated 3D microstrucutral attributes include the distribution of eutectic platelet thickness; the mean volume, mean surface area, and mean thickness of the eutectic Si platelets; the mean volume and the mean surface area of the polyhedral primary Si particles; and the mean number of faces, edges, and corners on the polyhedral primary Si particles.

  13. Exploration of the electrophoretic behaviour of borane cluster anions and of the capability of capillary electrophoresis to separate them chirally.

    Science.gov (United States)

    Slavícek, Viktor; Grüner, Bohumír; Vespalec, Radim

    2003-01-10

    Mobilities of investigated boron cluster compounds in 3-(N-morpholino)propanesulfonic and phosphate buffers adjusted to pH 7 either with sodium hydroxide or with tris(hydroxymethyl)aminomethane depend on both buffer ions. The zone width and zone asymmetry, which are usually markedly higher than those of organic or common inorganic ions of comparable size, depend on the type of the borane cluster anion. Unusual shapes of zones of two investigated compounds have been found in tris phosphate buffer. Acetonitrile was superior to methanol as an organic additive to separation systems from the viewpoint of the zone symmetry and separation speed. Narrow trigonal zones, typical of organic ions non-interacting with the capillary wall, have been observed for some bridged sandwich cobalt complexes in run buffers with the addition of acetonitrile. The interaction of borane cluster anions with beta-cyclodextrin cavity is excessively strong in purely aqueous solutions. Methanol and acetonitrile, which generally weaken the interaction, sometimes affect the separation enantioselectivity of various compounds in different ways in addition to the weakening effect. Chiral discrimination was reached for all ten investigated anions, which belong to four different structural types of cluster boranes. Stability constants estimated for some analyte-beta-cyclodextrin complexes range between 100 and 1800 l/mol in acceptable separations. The relative difference of the constants was from 3 to 20%. PMID:12564682

  14. The Planar CoB18 (-) Cluster as a Motif for Metallo-Borophenes.

    Science.gov (United States)

    Li, Wan-Lu; Jian, Tian; Chen, Xin; Chen, Teng-Teng; Lopez, Gary V; Li, Jun; Wang, Lai-Sheng

    2016-06-20

    Monolayer-boron (borophene) has been predicted with various atomic arrangements consisting of a triangular boron lattice with hexagonal vacancies. Its viability was confirmed by the observation of a planar hexagonal B36 cluster with a central six-membered ring. Here we report a planar boron cluster doped with a transition-metal atom in the boron network (CoB18 (-) ), suggesting the prospect of forming stable hetero-borophenes. The CoB18 (-) cluster was characterized by photoelectron spectroscopy and quantum chemistry calculations, showing that its most stable structure is planar with the Co atom as an integral part of a triangular boron lattice. Chemical bonding analyses show that the planar CoB18 (-) is aromatic with ten π-electrons and the Co atom has strong covalent interactions with the surrounding boron atoms. The current result suggests that transition metals can be doped into the planes of borophenes to create metallo-borophenes, opening vast opportunities to design hetero-borophenes with tunable chemical, magnetic, and optical properties. PMID:27094830

  15. Effects of localized boron states on the transport properties of n-BGaInAs

    International Nuclear Information System (INIS)

    The incorporation of isovalent boron on cation sites of GaAs results in strongly localized electronic states resonant with the conduction band. All present experimental and theoretical results indicate that these states have only minor influence on the conduction band structure. We show however that such states strongly affect the electronic transport behaviour of this unusual semiconductor alloy. We study the influence of these boron cluster states on the electronic transport of n-type BGaInAs-layers. We performed magnetotransport measurements at temperatures from 1.6 K to 300 K using magnetic fields up to 10 T and hydrostatic pressure up to 20 kbar. At ambient pressure and low carrier concentration both strong negative MR effects at low fields and a giant exponential positive MR at high magnetic fields can be observed. The latter is regarded as proof of a hopping transport mechanism and is interpreted as a metal insulator transition under the influence of an external magnetic field. Under hydrostatic pressure the results are dominated by the complex interplay between extended band states, localized boron states and dopant states

  16. Optical nanospectroscopy applications in material science

    International Nuclear Information System (INIS)

    The advent of scanning near-field optical microscopy (SNOM) has augmented at a microscopic level the usefulness of optical spectroscopy in the region between 300 nm and 10 μm. Two-dimensional imaging of chemical constituents makes this a very attractive and powerful new approach. In this paper we show SNOM results obtained in several geometrical configurations on boron clusters in silicon, Li clusters embedded in a LiF sample and BN growth on silicon. We also show some results on the wavelength dependence of the reflectivity (R) in the near infrared (IR) of biological cells in liquid environment with the observation of the local fluorescence. The SNOM images revealed features that were not present in the corresponding shear-force (SF) images and which were due to localized changes in the bulk properties of the sample. The size of the smallest detected features clearly demonstrated that near-field conditions were reached both in the visible and infrared region

  17. Electronic structure of the boron fullerene B14 and its silicon derivatives B13Si(+), B13Si(-) and B12Si2: a rationalization using a cylinder model.

    Science.gov (United States)

    Van Duong, Long; Nguyen, Minh Tho

    2016-06-29

    Geometric and electronic structures of the boron cluster B14 and its silicon derivatives B13Si(+), B13Si(-), and B12Si2 were determined using DFT calculations (TPSSh/6-311+G(d)). The B12Si2 fullerene, which is formed by substituting two B atoms at two apex positions of the B14 fullerene by two Si atoms, was also found as the global minimum structure. We demonstrated that the electronic structure and orbital configuration of these small fullerenes can be predicted by the wavefunctions of a particle on a cylinder. The early appearance of high angular node MOs in B14 and B12Si2 can be understood by this simple model. Replacement of one B atom at a top position of B14 by one Si atom, followed by the addition or removal of one electron does not lead to a global minimum fullerene structure for the anion B13Si(-) and cation B13Si(+). The early appearance of the 5σ1 orbital in B13Si(+) causes a lower stability for the fullerene-type structure. PMID:27306917

  18. Proceedings of workshop on 'boron chemistry and boron neutron capture therapy'

    International Nuclear Information System (INIS)

    This volume contains the proceedings of the 4th Workshop on 'the Boron Chemistry and Boron Neutron Capture Therapy' held on February 24 in 1992. First, clinical experiences of BNCT in the Kyoto University Research Reactor in 1992 were briefly reported. Then, the killing effects of boron cluster-containing nucleic acid precursors on tumor cells were shown (Chap. 2). The various trials of the optical resolution of B-p-boronophenylalanine for neutron capture therapy were made (Chap. 3). The borate-dextran gel complexes were investigated by the nuclear magnetic resonance spectroscopy. The stability constants of borate complexes were listed, and are useful in the solution chemistry of boron compounds (Chap. 4). The interactions between boron compounds and biological materials were studied by the paper electrophoresis which had been developed by us (Chap. 5). Molecular design of boron-10 carriers and their organic synthesis were reported (Chap. 6). Carborane-containing aziridine boron carriers which were directed to the DNA alkylation were synthesized and their cancer cell killing efficacies were tested (Chap. 7). The solution chemistry of deuterium oxide which is a good neutron moderator was reported, relating to the BNCT (Chap. 8). (author)

  19. CO2 capture and separation from N2/CH4 mixtures by Co@B8/Co@B8(-) and M@B9/M@B9(-) (M = Ir, Rh, Ru) clusters: a theoretical study.

    Science.gov (United States)

    Wang, Weihua; Zhang, Xiaoxiao; Li, Ping; Sun, Qiao; Li, Zhen; Ren, Cong; Guo, Chao

    2015-01-29

    The discovery of advanced materials with high selectivity and efficiency is essential to realize practical carbon capture and sequestration. Here, we have investigated the interactions of the Co@B8/Co@B8(-) and M@B9/M@B9(-) (M = Ir, Rh, Ru) clusters with CO2, N2, and CH4 gas molecules theoretically. We found that neutral boron clusters have weak interaction with CO2, N2, and CH4 molecules. Similarly, the clusters with their negative charge states have also weak interaction with N2 and CH4 molecules. However, anionic clusters have a strong interaction with CO2, which can be explained by the Lewis acid-base interaction as CO2 (Lewis acid) can gain electron easily from the electron-rich anionic clusters. Moreover, the kinetic stability of the formed complexes after CO2 capture has been validated by ab initio molecular dynamics. In all, the present study demonstrates, for the first time, that the anionic boron wheel ring clusters can be used as potential advanced materials for CO2 capture and separation from flue gas and natural gas mixtures. PMID:25594368

  20. Synthesis of triazolyl methyl-substituted amino- and oxy-undeca-hydro-dodeca-borates for potential application in boron neutron capture therapy

    International Nuclear Information System (INIS)

    A general approach to the synthesis of triazole conjugates containing undeca-hydro-closo-dodeca-borate anions based on Huisgen 1, 3-dipolar cycloaddition is presented. Un-decahydro-closo-dodeca-borate anions bearing terminal alkyne groups were synthesized by the reaction of H3N-B12H11- or HO-B12H112- with alkyne halides in N, N-dimethylformamide using KOH as a base. Variation of reaction time, alkyne halide concentration and steric demands of the alkyne halide resulted in the stepwise introduction of one to three alkyne groups into H3N-B12H11-. Two compounds {(CHCCH2)-N-B12H11- and (CHCCH2)O-B12H112-} were crystallized for single-crystal X-ray diffraction studies. N- and O-alkyne un-decahydro-closo-dodeca-borate anions reacted with various functionalized azides including lipid, carborane, aryl and hydroxyalkyl groups. The current study provides various synthetic applications not only for BNCT but also for boron cluster materials. (authors)

  1. Sources and transport systems for low energy extreme of ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch, A.; Batalin, V.A.; Bugaev, A.S.; Gushenets, V.I.; Alexeyenko, O.; Gurkova, E.; Johnson, B.M.; Kolomiets, A.A.; Kropachev, G.N.; Kuibeda, R.P.; Kulevoy, T.V.; Masunov, E.S.; Oks, E.M.; Pershin, V.I.; Polozov, S.M.; Poole, H.J.; Seleznev, D.N.; Storozhenko, P.A.; Vizir, A.; Svarovski, A.Ya.; Yakushin, P.; Yushkov, G.Yu.

    2010-06-06

    For the past seven years a joint research and development effort focusing on the design of steady state, intense ion sources has been in progress with the ultimate goal being to meet the two, energy extreme range needs of mega-electron-volt and 100's of electron-volt ion implanters. However, since the last Fortier is low energy ion implantation, focus of the endeavor has shifted to low energy ion implantation. For boron cluster source development, we started with molecular ions of decaborane (B{sub 10}H{sub 14}), octadecaborane (B{sub 18}H{sub 22}), and presently our focus is on carborane (C{sub 2}B{sub 10}H{sub 12}) ions developing methods for mitigating graphite deposition. Simultaneously, we are developing a pure boron ion source (without a working gas) that can form the basis for a novel, more efficient, plasma immersion source. Our Calutron-Berna ion source was converted into a universal source capable of switching between generating molecular phosphorous P{sub 4}{sup +}, high charge state ions, as well as other types of ions. Additionally, we have developed transport systems capable of transporting a very large variety of ion species, and simulations of a novel gasless/plasmaless ion beam deceleration method were also performed.

  2. Comparative characteristics of the morphology of rabbit lymph nodes after implantation of porous titanium with composite nanocoating and hydroxyapatite particles embedded into pores.

    Science.gov (United States)

    Makarova, E B; Kiselyova, N S; Smetankina, M A; Bliznets, D G; Rubstein, A P; Krokhina, N B

    2011-08-01

    We studied changes of microarchitectonics of lymph nodes in mature rabbits in response to introduction of bioimplants based on porous titanium with carbon-containing nanocoating or nanocoating with hydroxyapatite embedded into pores. Moderate local reactivity of the lymphoid system was observed in animals with implants coated with carbon-containing films within 30 days after surgery. In animals with nanocoated implants containing hydroxyapatite, the immune response was more pronounced. Introduction of implants led to activation of cellular and humoral mechanisms of immunity in animals of both groups. PMID:22448374

  3. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  4. Kinetics of structuring of submonolayer carbon coatings on silicon (100) crystals during microwave vacuum-plasma deposition

    Science.gov (United States)

    Yafarov, R. K.; Shanygin, V. Ya.

    2015-06-01

    The kinetics of self-organization of nanodomains during the deposition of submonolayer carbon coatings on (100) silicon in the microwave plasma of low-pressure ethanol vapors is studied by atomic force microscopy and scanning electron microscopy. The laws of influence of the substrate temperature and the kinetic energy of carbon-containing ions on the mechanisms of formation and structuring of the forming silicon-carbon surface phases are established. It is shown that the deposited carbon-containing nanodomains can be used as nonlithographic mask coatings for the formation of spatial low-dimensional systems on single-crystal silicon upon selective highly anisotropic plasma-chemical etching.

  5. Formation of ZrB2 in MgO-C Composite Materials Using In-Situ Synthesis Method

    Institute of Scientific and Technical Information of China (English)

    LI Lin; HONG Yan-ruo; SUN Jia-lin; HE Zhi-yong; PENG Xiao-yan

    2006-01-01

    ZrB2 in MgO-C composite materials obtained by both microwave sintering synthesis and in-situ reaction at lower temperature was investigated. The test result shows that 66.67% of reactant changed into ZrB2, and the other form Al2O3, which could optimize the properties of carbon-containing materials. Therefore, the method of in-situ synthesizing ZrB2 acting as antioxidant in carbon-containing materials is considered as one of best ways to reduce the cost and ZrB2 as refractories is used on a large-scale.

  6. Apparatus for producing carbon-coated nanoparticles and carbon nanospheres

    Science.gov (United States)

    Perry, W. Lee; Weigle, John C.; Phillips, Jonathan

    2015-10-20

    An apparatus for producing carbon-coated nano- or micron-scale particles comprising a container for entraining particles in an aerosol gas, providing an inlet for carbon-containing gas, providing an inlet for plasma gas, a proximate torch for mixing the aerosol gas, the carbon-containing gas, and the plasma gas, bombarding the mixed gases with microwaves, and providing a collection device for gathering the resulting carbon-coated nano- or micron-scale particles. Also disclosed is a method and apparatus for making hollow carbon nano- or micro-scale spheres.

  7. Mechanism of ruthenium dioxide crystallization during high level waste vitrification

    International Nuclear Information System (INIS)

    Ruthenium, arising from the reprocessing of spent uranium oxide fuel, has a low solubility in glass melt. It crystallizes in the form of particles of RuO2 of acicular or polyhedral morphology dispersed in fission product and actinides waste containment glass. Since the morphology of these particles strongly influences the physico-chemical properties, the knowledge and the control of their mechanism of formation are of major importance. The goal of this work is to determine the chemical reactions responsible for the formation of RuO2 particles of acicular or polyhedral shape during glass synthesis. Using a simplification approach, the reactions between RuO2-NaNO3, and more complex calcine RuO2-Al2O3-Na2O and a sodium borosilicate glass are studied. In situ scanning electron microscopy and XANES at increasing temperatures are used to follow changes in composition, speciation and morphology of the ruthenium intermediate species. Those compounds are thoroughly characterised by SEM, XRD, HRTEM, and ruthenium K-edge X-ray absorption spectroscopy. This combined approach allows us to show that the ruthenium speciation modification during vitrification is the key of control of the morphology of RuO2 particles in the glass. In particular, the formation of a specific intermediate compound (Na3RuO4) is one of the main steps that lead to the precipitation of needle-shaped RuO2 particles in the melt. The formation of polyhedral particles, on the contrary, results from the direct incorporation of RuO2 crystals in the melt followed by an Ostwald ripening mechanism. (author)

  8. Sulfur Poisoning of SOFC Anodes: Effect of Overpotential on Long-Term Degradation

    DEFF Research Database (Denmark)

    Hauch, Anne; Hagen, Anke; Hjelm, Johan;

    2014-01-01

    Sulfur impurities in carbon containing fuels for solid oxide fuel cells (SOFC), e.g. natural gas and biogas, typically lead to significant losses in performance due to the sulfur sensitivity of Ni/yttria-stabilized-zirconia (YSZ) anodes for SOFC. Full cells having Ni/YSZ anodes have been characte...

  9. Radiocarbon dating of holocene eruptions of the Elbrus volcano (North Caucasus, Russia)

    International Nuclear Information System (INIS)

    Carbon-containing materials formed as a result of the Elbrus volcano eruptions during the recent 10 thousand years are studied the radiocarbon dating method. Three differing in age episodes of the Elbrus volcano eruptions in holocene: the oldest (7200-7500 years ago), the middle (4600-5500 years ago) and the youngest (at the start of our era) ones were identified

  10. 5.5. Obtaining of cryolite-alumina concentrate from the production wastes and local aluminium-fluorine containing raw material

    International Nuclear Information System (INIS)

    The flowsheet of complex reprocessing of solid carbon containing wastes was elaborated. The flowsheet is presented in this article. The flowsheet including three methods: flotation, burning and sintering was considered. The flowsheet of obtaining of cryolite-alumina concentrate from the flotation tails of aluminium production was considered and presented in this article as well.

  11. Studies on the sublimation of tungsten single crystal (110) face and the influence of carbon

    International Nuclear Information System (INIS)

    Evaporation of tungsten single crystals face (110) is studied in ultrahigh vacuum (better than 1x10-9 torr) by Langmuir method. Small admixtures of carbon are shown to markedly influence the process. Carbon hinders the evaporation and increases the sublimation energy by 25 kcal. The data obtained show that the reported parametres of tungsten evaporation refer to a carbon-containing material

  12. Bioenergy Plants: Hopes, Concerns and Prospectives

    Institute of Scientific and Technical Information of China (English)

    Martin A.J.Parry; Hai-Chun Jing

    2011-01-01

    @@ There are major concerns over both the security of energy supplies (declining supplies and political control) and the en-vironmental costs associated with energy generation and use.The global consumption of carbon-containing fossil fuels for heat, electricity, transport and the manufacture of chemicals is not sustainable.

  13. Encapsulation of atmospheric CO2 by a self-assembled decanuclear cadmium complex via unfamiliar perchlorato and carbonato bridges.

    Science.gov (United States)

    García-Deibe, Ana M; Portela-García, Cristina; Fondo, Matilde; Mota, Antonio J; Sanmartín-Matalobos, Jesús

    2012-10-11

    A decanuclear Cd complex has been found as a carbonate-containing capsule. The structure strongly resembles a ten-blade waterwheel with a central carbonate ligand surrounded by two superimposed Cd(5)O(5) crowns with a pentagonal antiprism-like disposition. The capsule is doubly capped by two pentadentate perchlorate anions. PMID:22932953

  14. Self-assembly and Self-organization Processes of Carbon Nanotubes in the Colloidal Systems

    OpenAIRE

    A.P. Kuzmenko; Thet Phyo Naing; Myo Min Than; Chan Nyein Aung; M.B. Dobromyslov; S.G. Emelyanov; L.M. Chervyakov

    2015-01-01

    The features and patterns of self-organization processes in the diffusion-limited conditions (method of drops) of carbon-containing compounds and carbon nanotubes have been studied. The results of the research influence of the substrate temperature and solvent on the formation of nanoscale fractal structures in sediments of colloidal solutions are provided.

  15. Self-assembly and Self-organization Processes of Carbon Nanotubes in the Colloidal Systems

    Directory of Open Access Journals (Sweden)

    A.P. Kuzmenko

    2015-12-01

    Full Text Available The features and patterns of self-organization processes in the diffusion-limited conditions (method of drops of carbon-containing compounds and carbon nanotubes have been studied. The results of the research influence of the substrate temperature and solvent on the formation of nanoscale fractal structures in sediments of colloidal solutions are provided.

  16. R-Matrix Calculations of Electron Molecule Collision Data

    International Nuclear Information System (INIS)

    Results for R-matrix calculations performed during the Coordinated Research Project (CRP) on Atomic and Molecular Data for Plasma Modelling are discussed. Electron collision problems studied include collisions with various carbon containing molecules including C2, HCCH, CH4, C2H6 and C3H8. (author)

  17. Removal of sialoliths using the intraoral approach in 15 horses.

    Science.gov (United States)

    Oreff, Gil L; Shiraki, Ryoji; Kelmer, Gal

    2016-06-01

    This study describes the use of an intraoral approach for sialolith removal in horses. All horses resumed their previous activity after surgery. Sialoliths were composed mainly of calcium carbonate, containing a nidus of plant material. The removal of sialoliths via an intraoral approach results in a high success rate with minimal complications. PMID:27247466

  18. Design of $Cu_{8}Zr_{5}$-based bulk metallic glasses

    OpenAIRE

    Yang, L.; Xia, J H; Wang, Q; Dong, C; Chen, L. Y.; Ou, X; Liu, J. F.; Jiang, J. Z.; Klementiev, K.; Saksl, K.; Franz, H.; Schneider, J. R.; L. Gerward

    2006-01-01

    Basic polyhedral clusters have been derived from intermetallic compounds at near-eutectic composition by considering a dense packing and random arrangement of atoms at shell sites. Using such building units, bulk metallic glasses can be formed. This strategy was verified in the Cu-Zr binary system, where we have demonstrated the existence of Cu8Zr5 icosahedral clusters in Cu61.8Zr38.2, Cu64Zr36, and Cu64.5Zr35.5 amorphous alloys. Furthermore, ternary bulk metallic glasses can be developed by ...

  19. New Facets and a Branch-and-Cut Algorithm for the Weighted Clique Problem

    DEFF Research Database (Denmark)

    Sørensen, Michael Malmros

    2001-01-01

    We consider a polyhedral approach to the weighted maximal b-clique problem. Given a node- and edge-weighted complete graph the problem is to find a complete subgraph (clique) with no more than b nodes such that the sum of the weights of all nodes and edges in the clique is maximal. We introduce...... four new classes of facet defining inequalities for the associated b-clique polytope. One of these inequality classes constitutes a generalization of the well known tree inequalities; the other classes are associated with multistars. We utilize these inequality classes together with other classes of...

  20. New facets and a branch-and-cut algorithm for the weighted clique problem

    DEFF Research Database (Denmark)

    Sørensen, Michael Malmros

    2004-01-01

    We consider a polyhedral approach to the weighted maximal b-clique problem. Given a node- and edge-weighted complete graph the problem is to find a complete subgraph (clique) with no more than b nodes such that the sum of the weights of all nodes and edges in the clique is maximal. We introduce...... four new classes of facet defining inequalities for the associated b-clique polytope. One of these inequality classes constitutes a generalization of the well known tree inequalities; the other classes are associated with multistars. We use these inequalities together with other classes of facet...

  1. Two-party Bell inequalities derived from combinatorics via triangular elimination

    International Nuclear Information System (INIS)

    We establish a relation between the two-party Bell inequalities for two-valued measurements and a high-dimensional convex polytope called the cut polytope in polyhedral combinatorics. Using this relation, we propose a method, triangular elimination, to derive tight Bell inequalities from facets of the cut polytope. This method gives two hundred million inequivalent tight Bell inequalities from currently known results on the cut polytope. In addition, this method gives general formulae which represent families of infinitely many Bell inequalities. These results can be used to examine general properties of Bell inequalities

  2. Feature - Based Approach to Automatic Fixturing System Planning ForUniform Polyhedra Workpiece

    Directory of Open Access Journals (Sweden)

    Amjad Barzan

    2008-01-01

    Full Text Available This paper demonstrates the design of an algorithm to represent the design stages of fixturing system that serve in increasing the flexibility and automation of fixturing system planning for uniform polyhedral part. This system requires building a manufacturing feature recognition algorithm to present or describe inputs such as (configuration of workpiece and built database system to represents (production plan and fixturing system exiting to this algorithm. Also knowledge – base system was building or developed to find the best fixturing analysis (workpiece setup, constraints of workpiece and arrangement the contact on this workpiece to workpiece.

  3. Una aproximació polièdrica al concepte microeconòmic

    OpenAIRE

    Penélope Hernández; José Vila Gisbert

    2009-01-01

    Una aproximació polièdrica al concepte microeconòmicA Polyhedral Approach to the Microeconomic ConceptEste artículo propone un enfoque tridimensional de cualquier concepto en Microeconomía y analiza las implicaciones de esta multidimensionalidad en el proceso de aprendizaje-enseñanza de la microeconomía en educación universitaria. Las tres facetas del aprendizaje presentadas son la experiencial-vivencial, la gráfico-geométrica y la matemático-formal. En cada una de ellas el lenguaje utilizado...

  4. Hydrogen catalysis and scavenging action of Pd-POSS nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, A; Gee, R H; Maxwell, R; Saab, A

    2007-02-01

    Prompted by the need for a self-supported, chemically stable, and functionally flexible catalytic nanoparticle system, we explore a system involving Pd clusters coated with a monolayer of polyhedral oligomeric silsesquioxane (POSS) cages. With an initial theoretical focus on hydrogen catalysis and sequestration in the Pd-POSS system, we report Density Functional Theory (DFT) results on POSS binding energies to the Pd(110) surface, hydrogen storing ability of POSS, and possible pathways of hydrogen radicals from the catalyst surface to unsaturated bonds away from the surface.

  5. Controlled Assembly of Endohedrally-Functionalized Metal-Ligand Supramolecular Complexes

    OpenAIRE

    Johnson, Amber

    2014-01-01

    An area of supramolecular chemistry that has recently been growing in popularity is the synthesis of metal-ligand cages. These are most commonly comprised of organic ligands and transition metal ions. Cage complexes often take the form of geometric polyhedra such as tetrahedra and octahedra, where the ligands act as the edges or faces and the metals serve as the vertices. Because these complexes have a polyhedral design, there is a central cavity in the cage, and this has been exploited for g...

  6. Tunable pretilt angles based on nanoparticles-doped planar liquid-crystal cells.

    Science.gov (United States)

    Jeng, Shie-Chang; Hwang, Shug-June; Yang, Chen-Yu

    2009-02-15

    The nanoparticles-induced vertical alignment technique was applied to generate variable liquid-crystal pretilt angles based on doping different concentrations of polyhedral oligomeric silsesquioxane (POSS) nanoparticles in the planar-aligned liquid crystal cells. Competition between the homogeneously aligned polyimide layer and POSS-induced spontaneous vertical alignment domain generated the variable pretilt angle. Experimental results demonstrated that the pretilt angle theta(p) is a function of the doped POSS concentration and can be controlled continuously over the range of 0 degrees

  7. Analysis of Human T-Cell Leukemia Virus Type 1 Particles by Using Cryo-Electron Tomography

    Science.gov (United States)

    Cao, Sheng; Maldonado, José O.; Grigsby, Iwen F.

    2014-01-01

    The particle structure of human T-cell leukemia virus type 1 (HTLV-1) is poorly characterized. Here, we have used cryo-electron tomography to analyze HTLV-1 particle morphology. Particles produced from MT-2 cells were polymorphic, roughly spherical, and varied in size. Capsid cores, when present, were typically poorly defined polyhedral structures with at least one curved region contacting the inner face of the viral membrane. Most of the particles observed lacked a defined capsid core, which likely impacts HTLV-1 particle infectivity. PMID:25473052

  8. Surface-enhanced raman spectroscopy substrate for arsenic sensing in groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Peidong; Mulvihill, Martin; Tao, Andrea R.; Sinsermsuksakul, Prasert; Arnold, John

    2015-06-16

    A surface-enhanced Raman spectroscopy (SERS) substrate formed from a plurality of monolayers of polyhedral silver nanocrystals, wherein at least one of the monolayers has polyvinypyrrolidone (PVP) on its surface, and thereby configured for sensing arsenic is described. Highly active SERS substrates are formed by assembling high density monolayers of differently shaped silver nanocrystals onto a solid support. SERS detection is performed directly on this substrate by placing a droplet of the analyte solution onto the nanocrystal monolayer. Adsorbed polymer, polyvinypyrrolidone (PVP), on the surface of the nanoparticles facilitates the binding of both arsenate and arsenite near the silver surface, allowing for highly accurate and sensitive detection capabilities.

  9. An investigation of muon sites in YBa2Cu3O6 by using Density Functional Theory

    International Nuclear Information System (INIS)

    The electrostatic potential has been investigated in YBa2Cu3O6 by applying the density functional theory in order to estimate possible muon sites. We found five minimum potential positions around the apical oxygen of the CuO5 polyhedral. In addition to those, we also found another minimum potential position near the yttrium atom which is in between the CuO2 layers. Those estimated positions are different from those suggested from previous μSR studies on the basis of the dipole-field estimation

  10. Combinatorial topology of three-dimensional self-affine tiles

    CERN Document Server

    Bandt, Christoph

    2010-01-01

    We develop tools to study the topology and geometry of self-affine fractals in dimension three and higher. We use the self-affine structure and obtain rather detailed information about the connectedness of interior and boundary sets, and on the dimensions and intersections of boundary sets. As an application, we describe in algebraic terms the polyhedral structure of the six fractal three-dimensional twindragons. Only two of them can be homeomorphic to a ball but even these have faces which are not homeomorphic to a disk.

  11. Continuity Results and Error Bounds on Pseudomonotone Vector Variational Inequalities via Scalarization

    Directory of Open Access Journals (Sweden)

    Xin Zuo

    2016-01-01

    Full Text Available Continuity (both lower and upper semicontinuities results of the Pareto/efficient solution mapping for a parametric vector variational inequality with a polyhedral constraint set are established via scalarization approaches, within the framework of strict pseudomonotonicity assumptions. As a direct application, the continuity of the solution mapping to a parametric weak Minty vector variational inequality is also discussed. Furthermore, error bounds for the weak vector variational inequality in terms of two known regularized gap functions are also obtained, under strong pseudomonotonicity assumptions.

  12. Carbon nanostructures obtained by underwater arc discharge of graphite electrodes: Synthesis and characterization

    International Nuclear Information System (INIS)

    In the present work, the application of the method of underwater arc discharge of graphite electrodes for obtaining several carbon nano structures is described. The analysis of the obtained products by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Raman spectroscopy, Atomic Force Microscopy (AFM) and X-Ray Diffraction (XRD) showed that the samples collected from the material floating on the water surface were composed mainly by polyhedral onion-like particles, while those taken from the precipitate were a mixture multi walled nano-tubes, onion-like particles and other graphitic structures. The main features of the obtained nano structures are discussed. (Author)

  13. The generic Gröbner walk

    DEFF Research Database (Denmark)

    Jensen, Anders Nedergaard; Lauritzen, Niels; Fukuda, Komei;

    2005-01-01

    The Gröbner walk is an algorithm for conversion between Gröbner bases for different term orders. It is based on the polyhedral geometry of the Gröbner fan and involves tracking a line between cones representing the initial and target term order. An important parameter is explicit numerical...... perturbation of this line. This usually involves both time and space demanding arithmetic of integers much larger than the input numbers. In this paper we show how the explicit line may be replaced by a formal line using Robbiano's characterization of group orders on . This gives rise to the generic Gröbner...

  14. An LP-based heuristic for the fixed charge transportation problem

    DEFF Research Database (Denmark)

    Klose, Andreas

    2007-01-01

    The fixed charge transportation problem consists in finding a minimum cost network flow from a set of suppliers to a set of customers. Beside costs proportional to quantities transported, transportation costs also include a fixed charge. The paper describes a linear programming based heuristic...... approach for computing lower and upper bounds on the minimal cost. To this end, the LP relaxation is iteratively strengthened by means of adding cuts; in each iteration the current LP solution is then used to guide a local search heuristic. In addition to standard polyhedral cuts as lifted cover...

  15. Computational Methods Development at Ames

    Science.gov (United States)

    Kwak, Dochan; Smith, Charles A. (Technical Monitor)

    1998-01-01

    This viewgraph presentation outlines the development at Ames Research Center of advanced computational methods to provide appropriate fidelity computational analysis/design capabilities. Current thrusts of the Ames research include: 1) methods to enhance/accelerate viscous flow simulation procedures, and the development of hybrid/polyhedral-grid procedures for viscous flow; 2) the development of real time transonic flow simulation procedures for a production wind tunnel, and intelligent data management technology; and 3) the validation of methods and the flow physics study gives historical precedents to above research, and speculates on its future course.

  16. LinKnot knot theory by computer

    CERN Document Server

    Jablan, Slavik

    2007-01-01

    LinKnot - Knot Theory by Computer provides a unique view of selected topics in knot theory suitable for students, research mathematicians, and readers with backgrounds in other exact sciences, including chemistry, molecular biology and physics. The book covers basic notions in knot theory, as well as new methods for handling open problems such as unknotting number, braid family representatives, invertibility, amphicheirality, undetectability, non-algebraic tangles, polyhedral links, and (2,2)-moves. Hands-on computations using Mathematica or the webMathematica package LinKnot (available online

  17. Discrete Element Method Simulation of a Boulder Extraction From an Asteroid

    Science.gov (United States)

    Kulchitsky, Anton K.; Johnson, Jerome B.; Reeves, David M.; Wilkinson, Allen

    2014-01-01

    The force required to pull 7t and 40t polyhedral boulders from the surface of an asteroid is simulated using the discrete element method considering the effects of microgravity, regolith cohesion and boulder acceleration. The connection between particle surface energy and regolith cohesion is estimated by simulating a cohesion sample tearing test. An optimal constant acceleration is found where the peak net force from inertia and cohesion is a minimum. Peak pulling forces can be further reduced by using linear and quadratic acceleration functions with up to a 40% reduction in force for quadratic acceleration.

  18. The Galerkin finite element method for a multi-term time-fractional diffusion equation

    KAUST Repository

    Jin, Bangti

    2015-01-01

    © 2014 The Authors. We consider the initial/boundary value problem for a diffusion equation involving multiple time-fractional derivatives on a bounded convex polyhedral domain. We analyze a space semidiscrete scheme based on the standard Galerkin finite element method using continuous piecewise linear functions. Nearly optimal error estimates for both cases of initial data and inhomogeneous term are derived, which cover both smooth and nonsmooth data. Further we develop a fully discrete scheme based on a finite difference discretization of the time-fractional derivatives, and discuss its stability and error estimate. Extensive numerical experiments for one- and two-dimensional problems confirm the theoretical convergence rates.

  19. Scanning and transmission electron microscopy of a craniopharyngioma: x-ray microanalytical study of the intratumoral mineralized deposits

    Energy Technology Data Exchange (ETDEWEB)

    Vilches, J.; Lopez, A.; Martinez, M.C.; Gomez, J.; Barbera, J.

    This paper discusses the value of scanning electron microscopy (SEM) and x-ray microanalysis in the classification of craniopharyngiomas. This neoplasm shows epithelial nest, cords of cuboid cells, foci of squamous metaplasia, and microcystic degeneration. SEM reveals that the epithelial cysts are lined with elongated cells that possess numerous microvilli and blebs and that some cysts are lined with polyhedral cells. The microvilli are interpreted as characteristic of the fast growing craniopharyngiomas. A microanalytical study of the calcified areas reveals the presence of magnesium, phosphorus, and calcium.

  20. Fabrication of Colloidal Clusters of Polymer Microspheres and Nonspherical Hollow Micro-particles from Pickering Emulsions

    International Nuclear Information System (INIS)

    We have introduced the Pickering emulsion systems to generate novel confining geometries for the selforganization of monodisperse polymer microspheres using nanoparticle-stabilized emulsion droplets encapsulating the building block particles. Then, through the slow evaporation of emulsion phases by heating, these microspheres were packed into regular polyhedral colloidal clusters covered with nanoparticle-stabilizers made of silica. Furthermore, polymer composite colloidal clusters were burnt out leaving nonspherical hollow micro-particles, in which the configurations of the cluster structure were preserved during calcination. The self assembled porous architectures in this study will be potentially useful in various applications such as novel building block particles or supporting materials for catalysis or gas adsorption

  1. L’hyperterminotique, un modèle paradigmatique d’organisation du savoir

    OpenAIRE

    Surmont, Jean-Nicolas de

    2012-01-01

    La représentation linéaire de la connaissance ne peut rendre compte de la nature polyèdre du terme. Le néologisme hyperterminotique désigne les situations ou processus d’organisation et de gestion de termes et de terminologies par le biais d’outils hypertextuels à l’intérieur des réseaux. L’hyperterminotique débouche sur une définition éthique du concept de paradigme. A linear knowledge representation cannot assume the polyhedral nature of terms. What we call hyperterminotics includes situ...

  2. The effect of BmNPV infection on protein metabolism in silkworm (Bombyx mori) larva

    OpenAIRE

    K Etebari; L Matindoost; SZ Mirhoseini; MW Turnbull

    2007-01-01

    Grasseri is one of the most important diseases of silkworm with significant yield loss, which is caused by nuclear polyhedrosis viruses (NPV). In the present research the effect of this disease on changes of biochemical compounds which are related to protein metabolism in 5th instar larvae were studied. The larvae that showed the grasseri symptoms after contamination with 5.5×10-4 polyhedral/ml were assumed as infected treatment. The hemolymph of infected and uninfected larvae in 3 and 5 days...

  3. On the vehicle routing problem with time windows

    DEFF Research Database (Denmark)

    Kallehauge, Brian

    2006-01-01

    eliminate time and capacity infeasible paths. We present a new class of strengthened path inequalities based on polyhedral results obtained in the context of the asymmetric traveling salesman problem with replenishment arcs. We study the VRPTW polytope and determine the polytope dimension. We show that the...... lifted path inequalities are facet defining under certain assumptions. We also introduce precedence constraints in the context of the VRPTW. Computational experiments are performed with a branch-and-cut algorithm on the Solomon test problems with wide time windows. Based on results on 25-node problems...

  4. Path inequalities for the vehicle routing problem with time windows

    DEFF Research Database (Denmark)

    Kallehauge, Brian; Boland, Natashia; Madsen, Oli B.G.

    2007-01-01

    the advantage of avoiding additional variables and linking constraints. In the new formulation, time windows are modeled using path inequalities that eliminate time and capacity infeasible paths. We present a new class of strengthened path inequalities based on the polyhedral results obtained by Mak...... (Ph.D. Thesis, 2001) for a variant of the TSP. We study the VRPTW polytope and determine its dimension. We show that the lifted path inequalities are facet defining under certain assumptions. We also introduce precedence constraints in the context of the VRPTW. Computational experiments are performed...

  5. Visualization system for intelligent robot simulation

    International Nuclear Information System (INIS)

    Simulation systems for intelligent robot has been developed at JAERI as a research and development program of underlying technologies for intelligent robots and intelligent nuclear plants. In the system, it is numerically/logically simulated that a human shaped robot reads and understands instructions written in natural language, planning and producing a required sequence of actions with environmental data. In such a simulation for actual nuclear facilities, it is indispensable to model the large scale environment and to visualize the simulation results for performance evaluation. We describe a modeling method with CSG (Constructive Solid Geometry), accurate visualization system by Ray Tracing method and high-speed visualization system using polyhedral model. (author)

  6. Acoustic Echoes Reveal Room Shape

    OpenAIRE

    Dokmanic, Ivan; Parhizkar, Reza; Walther, Andreas; Lu, Yue M.; Vetterli, Martin

    2013-01-01

    Imagine that you are blindfolded inside an unknown room. You snap your fingers and listen to the room’s response. Can you hear the shape of the room? Some people can do it naturally, but can we design computer algorithms that hear rooms? We show how to compute the shape of a convex polyhedral room from its response to a known sound, recorded by a few microphones. Geometric relationships between the arrival times of echoes enable us to “blindfoldedly” estimate the room geometry. This is achiev...

  7. Regular figures

    CERN Document Server

    Tóth, L Fejes; Ulam, S; Stark, M

    1964-01-01

    Regular Figures concerns the systematology and genetics of regular figures. The first part of the book deals with the classical theory of the regular figures. This topic includes description of plane ornaments, spherical arrangements, hyperbolic tessellations, polyhedral, and regular polytopes. The problem of geometry of the sphere and the two-dimensional hyperbolic space are considered. Classical theory is explained as describing all possible symmetrical groupings in different spaces of constant curvature. The second part deals with the genetics of the regular figures and the inequalities fo

  8. Graphics gems

    CERN Document Server

    Heckbert, Paul S

    1994-01-01

    Graphics Gems IV contains practical techniques for 2D and 3D modeling, animation, rendering, and image processing. The book presents articles on polygons and polyhedral; a mix of formulas, optimized algorithms, and tutorial information on the geometry of 2D, 3D, and n-D space; transformations; and parametric curves and surfaces. The text also includes articles on ray tracing; shading 3D models; and frame buffer techniques. Articles on image processing; algorithms for graphical layout; basic interpolation methods; and subroutine libraries for vector and matrix algebra are also demonstrated. Com

  9. Model-based recognition of 3-D objects by geometric hashing technique

    International Nuclear Information System (INIS)

    A model-based object recognition system is developed for recognition of polyhedral objects. The system consists of feature extraction, modelling and matching stages. Linear features are used for object descriptions. Lines are obtained from edges using rotation transform. For modelling and recognition process, geometric hashing method is utilized. Each object is modelled using 2-D views taken from the viewpoints on the viewing sphere. A hidden line elimination algorithm is used to find these views from the wire frame model of the objects. The recognition experiments yielded satisfactory results. (author). 8 refs, 5 figs

  10. Metrics of Justice. A Sundial's Nomological Figuration.

    Science.gov (United States)

    Behrmann, Carolin

    2015-01-01

    This paper examines a polyhedral dial from the British Museum made by the instrument maker Ulrich Schniep, and discusses the status of multifunctional scientific instruments. It discerns a multifaceted iconic meaning considering different dimensions such as scientific functionality (astronomy), the complex allegorical figure of Justice (iconography), and the representation of the sovereign (politics), the court and the Kunstkammer of Albrecht v of Bavaria. As a numen mixtum the figure of "Justicia" touches different fields that go far beyond pure astronomical measurement and represents the power of the ruler as well as the rules of economic justice. PMID:26495587

  11. The influence of air duct geometry on air jet direction in aircraft cabin ventilated by mixing ventilation.

    Science.gov (United States)

    Fišer, J.; Jícha, M.

    2013-04-01

    The paper deals with instigation of influence of air duct geometry on air jet direction in aircraft cabin ventilated by mixing ventilation. CFD approach was used for investigation and model geometry was based on small aircraft cabin mock-up geometry. Model was also equipped by nine seats and five manikins that represent passengers. The air jet direction was observed for selected ambient environment parameters and several types of air duct geometry and influence of main air duct geometry on jets direction is discussed. The model was created in StarCCM+ ver. 6.04.014 software and polyhedral mesh was used.

  12. The influence of air duct geometry on air jet direction in aircraft cabin ventilated by mixing ventilation.

    Directory of Open Access Journals (Sweden)

    Jícha M.

    2013-04-01

    Full Text Available The paper deals with instigation of influence of air duct geometry on air jet direction in aircraft cabin ventilated by mixing ventilation. CFD approach was used for investigation and model geometry was based on small aircraft cabin mock-up geometry. Model was also equipped by nine seats and five manikins that represent passengers. The air jet direction was observed for selected ambient environment parameters and several types of air duct geometry and influence of main air duct geometry on jets direction is discussed. The model was created in StarCCM+ ver. 6.04.014 software and polyhedral mesh was used.

  13. Syntheses of Boron Nitride Nanotubes from Borazine and Decaborane Molecular Precursors by Catalytic Chemical Vapor Deposition with a Floating Nickel Catalyst

    OpenAIRE

    Chatterjee, Shahana; Kim, Myung Jong; Zakharov, Dmitri; Kim, Seung Min; Stach, Eric A.; Maruyama, Benji; Sneddon, Larry G.

    2012-01-01

    Multi- and double-walled boron nitride nanotubes (BNNTs) have been synthesized with the aid of a floating nickel catalyst via the catalytic chemical vapor deposition (CCVD) of either the amine-borane borazine (B3N3H6) or the polyhedral-borane decaborane (B10H14) molecular precursors in ammonia atmospheres. Both sets of BNNTs were crystalline with highly ordered structures. The BNNTs grown at 1200 degrees C from borazine were mainly double-walled, with lengths up to 0.2 mu m and similar to 2 n...

  14. [Morphological diversity of Pandorina morum (Mull.) Vory (Volvocaceae) colonies].

    Science.gov (United States)

    Voĭtekhovskiĭ, Iu L

    2001-01-01

    Morphological variability of polyhedral colonies of green algae (Volvocaceae) were studied using some elements of combinative theory of polyhedron and the theory of diophantine equations. These colonies are considered as results of self-organization according to topological regularities of sphere dissection by convex polygons. It was shown that in three-dimensional Euclidean space for each colony of Pandorina morum (Müll.) Bory only three different forms are possible. One of them has no plane of symmetry and, thus, has two enantiomorphous varieties. It is suggested that frequency spectrum of forms can be used as potential indicator of environment pollution. PMID:11605552

  15. Line drawing interpretation

    CERN Document Server

    Cooper, Martin

    2010-01-01

    The computer interpretation of line drawings is a classic problem in AI and has inspired the development of some fundamental AI tools. This novel approach to drawing interpretation combines new constraints with recent advances in soft constraint programming, Based on the author's considerable research experience, this book contains state-of-the-art reviews of work in drawing interpretation and discrete optimisation and is not just restricted to drawings of polyhedral objects, but also covers complex curved objects. The book will become a standard reference in the field with its coverage of man

  16. Nanotechnology and bio-functionalisation for peripheral nerve regeneration

    Institute of Scientific and Technical Information of China (English)

    Tina Sedaghati; Alexander M Seifalian

    2015-01-01

    There is a high clinical demand for new smart biomaterials, which stimulate neuronal cell pro-liferation, migration and increase cell-material interaction to facilitate nerve regeneration across these critical-sized defects. This article brielfy reviews several up-to-date published studies using Arginine-Glycine-Aspartic acid peptide sequence, nanocomposite based on polyhedral oligo-meric silsesquioxane nanoparticle and nanoifbrous scaffolds as promising strategies to enhance peripheral nerve regeneration by inlfuencing cellular behaviour such as attachment, spreading and proliferation. The aim is to establish the potent manipulations, which are simple and easy to employ in the clinical conditions for nerve regeneration and repair.

  17. Homotopy theory the mathematical works of J. H. C. whitehead

    CERN Document Server

    James, I M

    1962-01-01

    Homotopy Theory contains all the published mathematical work of J. H. C. Whitehead, written between 1947 and 1955. This volume considers the study of simple homotopy types, particularly the realization of problem for homotopy types. It describes Whitehead's version of homotopy theory in terms of CW-complexes.This book is composed of 21 chapters and begins with an overview of a theorem to Borsuk and the homotopy type of ANR. The subsequent chapters deal with four-dimensional polyhedral, the homotopy type of a special kind of polyhedron, and the combinatorial homotopy I and II. These topics are

  18. Matching and Clustering: Two Steps Towards Object Modelling in Computer Vision

    OpenAIRE

    Gros, Patrick

    1995-01-01

    International audience In this article, we present a general frame for a system of au tomatic modeling and recognition of 3D polyhedral objects. Such a system has many applications for robotics: e.g., recog nition, localization, and grasping. Here we focus on one main aspect of the system: when many images of one 3D object are taken from different unknown viewpoints, how to recognize those that represent the same aspect of the object? Briefly, is it possible to determine automatically if t...

  19. Designing superhydrophobic surfaces using fluorosilsesquioxane-urethane hybrid and porous silicon gradients

    Science.gov (United States)

    Kannan, Aravindaraj G.; McInnes, Steven J. P.; Choudhury, Namita R.; Dutta, Naba K.; Voelcker, Nicolas H.

    2008-12-01

    Here we describe a new class of near superhydrophobic surfaces formed using fluorinated polyhedral oligosilsesquioxane (FluoroPOSS) urethane hybrids and porous silicon gradients (pSi). We demonstrate that the surface segregation behavior of the hydrophobic fluoro component can be controlled by the type and nature of chain extender of the urethane and resultant hydrophobic association via intra or intermolecular aggregation. The surface film formed exhibits near superhydrophobicity. This work has significant potential for applications in antifouling and self-cleaning coatings, biomedical devices, microfluidic systems and tribological surfaces.

  20. High-resolution CT of lymphoid interstitial pneumonia

    International Nuclear Information System (INIS)

    Three patients with lymphoid interstitial pneumonia (two HIV 1+ patients with chronic lymphadenopathic syndromes and one with a not-characterized autoimmune disease) have been studied with high-resolution computed tomography (HR-CT). This technique reveals septal lines, small reticulonodular opacities, polyhedral micronodular opacities, 'ground-glass' opacities and a dense, subpleural, curved broken line in one patient. The lesions dominate in the bases of the lungs. They are not characteristic for lymphoid interstitial pneumonia. If a patient presents with a chronic lymphadenopathic syndrome, the diagnosis of an opportunistic infection should not be automatically made, since the syndrome can be caused by lymphoid interstitial pneumonia

  1. Mimetic Finite Differences for Flow in Fractures from Microseismic Data

    KAUST Repository

    Al-Hinai, Omar

    2015-01-01

    We present a method for porous media flow in the presence of complex fracture networks. The approach uses the Mimetic Finite Difference method (MFD) and takes advantage of MFD\\'s ability to solve over a general set of polyhedral cells. This flexibility is used to mesh fracture intersections in two and three-dimensional settings without creating small cells at the intersection point. We also demonstrate how to use general polyhedra for embedding fracture boundaries in the reservoir domain. The target application is representing fracture networks inferred from microseismic analysis.

  2. Algebraic Systems Biology: A Case Study for the Wnt Pathway.

    Science.gov (United States)

    Gross, Elizabeth; Harrington, Heather A; Rosen, Zvi; Sturmfels, Bernd

    2016-01-01

    Steady-state analysis of dynamical systems for biological networks gives rise to algebraic varieties in high-dimensional spaces whose study is of interest in their own right. We demonstrate this for the shuttle model of the Wnt signaling pathway. Here, the variety is described by a polynomial system in 19 unknowns and 36 parameters. It has degree 9 over the parameter space. This case study explores multistationarity, model comparison, dynamics within regions of the state space, identifiability, and parameter estimation, from a geometric point of view. We employ current methods from computational algebraic geometry, polyhedral geometry, and combinatorics. PMID:26645985

  3. Interactive Modeling of Architectural Freeform Structures - Combining Geometry with Fabrication and Statics

    KAUST Repository

    Jiang, Caigui

    2014-09-01

    This paper builds on recent progress in computing with geometric constraints, which is particularly relevant to architectural geometry. Not only do various kinds of meshes with additional properties (like planar faces, or with equilibrium forces in their edges) become available for interactive geometric modeling, but so do other arrangements of geometric primitives, like honeycomb structures. The latter constitute an important class of geometric objects, with relations to “Lobel” meshes, and to freeform polyhedral patterns. Such patterns are particularly interesting and pose research problems which go beyond what is known for meshes, e.g. with regard to their computing, their flexibility, and the assessment of their fairness.

  4. Magnetic and Thermoelectric Properties of Boron-Rich Solids

    Science.gov (United States)

    Mori, Takao

    Boron forms various compounds with metal atoms occupying voids in the boron framework. As a synthesis method it has been found that the addition of small amounts of third elements like carbon, nitrogen, and silicon can result in the formation of novel and varied rare earth boron cluster structures. A wide variation of 1D, 2D, and 3D magnetic behavior with unexpectedly strong magnetic interactions has been discovered in rare earth boron icosahedra compounds which are magnetically dilute, f-electron insulators. As an intriguing phenomenon, the B12 icosahedra cluster, which is a building block of the structure, has been indicated to function as a novel mediator of magnetic interaction. These phenomena are borides. Attractive high temperature thermoelectric properties are also emerging in borides. Attractive high temperature thermoelectric properties are also emerging in this group of compounds, which is striking due to the great potential of utilizing waste heat. Recent developments on the long awaited n-type counterpart to boron carbide, the homologous series of RE-B-C(N) compounds, REB17CN, REB22C2N, and REB28.5C4, will be presented together with those of p-type REB44Si2. General new ways to improve the thermoelectric properties are also discussed. For example, seeding with highly electrically conductive metallic borides like REB4 and REB6 is found to be a way to significantly increase the thermoelectric figure of merit. Electric resistivity significantly decreases while Seebeck coefficients and thermal conductivity are not sizably affected.

  5. Design of Cu8Zr5-based bulk metallic glasses

    DEFF Research Database (Denmark)

    Yang, L.; Xia, J.H.; Wang, Q.; Dong, C.; Chen, L.Y.; Ou, X.; Liu, J.F.; Jiang, J.Z.; Klementiev, K.; Saksl, K.; Franz, H.; Schneider, J.R.; Gerward, Leif

    2006-01-01

    Basic polyhedral clusters have been derived from intermetallic compounds at near-eutectic composition by considering a dense packing and random arrangement of atoms at shell sites. Using such building units, bulk metallic glasses can be formed. This strategy was verified in the Cu-Zr binary syste.......382)(100-x)Nb-x, where x=1.5 and 2.5 at. %, and (Cu0.618Zr0.382)(98)Sn-2. The present results may open a route to prepare amorphous alloys with improved glass forming ability.......Basic polyhedral clusters have been derived from intermetallic compounds at near-eutectic composition by considering a dense packing and random arrangement of atoms at shell sites. Using such building units, bulk metallic glasses can be formed. This strategy was verified in the Cu-Zr binary system......, where we have demonstrated the existence of Cu8Zr5 icosahedral clusters in Cu61.8Zr38.2, Cu64Zr36, and Cu64.5Zr35.5 amorphous alloys. Furthermore, ternary bulk metallic glasses can be developed by doping the basic Cu-Zr alloy with a minority element. This hypothesis was confirmed in systems (Cu0.618Zr0...

  6. Next generation covered stents made from nanocomposite materials: A complete assessment of uniformity, integrity and biomechanical properties.

    Science.gov (United States)

    Farhatnia, Yasmin; Pang, Jun Hon; Darbyshire, Arnold; Dee, Ryan; Tan, Aaron; Seifalian, Alexander M

    2016-01-01

    Covered stents are stents wrapped with a thin polymeric membrane, and are typically used to treat vessel aneurysms and seal perforated arteries. Current covered stents suffer from restenosis due to limitations in material and fabrication methods which leaves metallic struts directly exposed to blood. We have developed a biocompatible and haemocompatible nanocomposite polymer, polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU). We devised a novel combination of ultrasonic spray atomisation system and dip-coating process to produce small calibre covered stents with metal struts fully embedded within the membrane, which also yields greater coating uniformity. Stent-polymer bonding was enhanced via silanisation and coating of reactive pre-polymer. Platelet studies supported the non-thrombogenicity of POSS-PCU. Biomechanical performances including diametrical compliance, bending strength, radial strength and recoil were evaluated and optimised. This proof-of-principle manufacturing technique could lead to the development of next-generation small calibre adult and paediatric covered stents. These stents are currently undergoing preclinical trial. From the Clinical Editor: The use of stents to treat vascular diseases is now the standard of care in the clinical setting. Nonetheless, a major problem of the current stents is the risk of restenosis and thrombosis. The authors developed a nanocomposite material using polyhedral oligomeric silsesquioxane and poly(carbonate-urea) urethane (POSS-PCU) and incorporated into metallic stents. Preliminary data have already shown promising results. It is envisaged that this would further lead to better stent technology in the future. PMID:26238080

  7. One-pot synthesis of high-index faceted AgCl nanocrystals with trapezohedral, concave hexoctahedral structures and their photocatalytic activity

    Science.gov (United States)

    Zhang, Haibin; Lu, Yonggang; Liu, Hong; Fang, Jingzhong

    2015-07-01

    AgCl semiconductor nanocrystals (NCs) with trapezohedral (TPH) and concave hexoctahedral (HOH) structures have been successfully synthesized for the first time in high yield by a direct one-pot solvothermal method. The as-prepared TPH, concave HOH AgCl NCs with unconventional polyhedral shapes and smooth surfaces were enclosed by 24 high-index {311} facets and 48 high-index {15 5 2} facets, respectively. A specific ionic liquid poly(diallyldimethylammonium) chloride (PDDA) acted as both a Cl- ion precursor and a morphology-controlled stabilizer, which was indispensable for the formation of these high-index faceted AgCl polyhedra and the derived uniform octahedral AgCl in an appropriate concentration of hot AgNO3 and ethylene glycol (EG) solution. With high-index facets exposed, both TPH and concave HOH AgCl NCs exhibit much higher photocatalytic activity than octahedral AgCl NCs that have mainly {111} faces exposed, with lower surface areas and surface energies, for the degradation of organics under sunlight. It is expected that the use of polyhedral AgCl NCs with high-index facets is an effective approach for the design of alternative semiconductor photocatalysts with a high performance, which may find potential applications such as in photochromics and environmental management.

  8. Mizunami Underground Research Laboratory project. Rock mechanical investigations in situ stress measurements using core-based methods on the -300 m stage

    International Nuclear Information System (INIS)

    The Mizunami Underground Research Laboratory (MIU) Project has been implemented to establish techniques for investigation, analysis and assessment of the deep geological environment and to develop a range of engineering techniques for application deep underground. In this report, results of Differential Strain Curve Analysis (DSCA) and elastic wave measurements using polyhedral specimens from the 08MI13 and 09MI20 boreholes on -300 m Stage at the MIU are described. The objectives of this work are to understand in situ stress condition around -300 m Stage and confirm validity of in situ stress measurements during the surface-based investigation phase. The results are summarized as follows; (1) The maximum principal stress is distributed in a NW-SE direction in the 08MI13 borehole. This result corresponds with in situ stress measurement results obtained during the surface-based investigation and construction phases. However the maximum principal stresses determined in the 09MI20 borehole have such a wide range that a consistent interpretation is difficult. (2) The ranges and averages of the principal stress ratios are almost equivalent and show less than two in the 08MI13 and 09MI20 boreholes. (3) Principal values from the DSCA and elastic wave measurements using polyhedral specimens from the 08MI13 and 09MI20 boreholes are compared. Although consistency of principal value for 08MI13 borehole isn't observed, results for 09MI20 come out the opposite of 08MI13. (author)

  9. Engineered protein nano-compartments for targeted enzyme localization.

    Directory of Open Access Journals (Sweden)

    Swati Choudhary

    Full Text Available Compartmentalized co-localization of enzymes and their substrates represents an attractive approach for multi-enzymatic synthesis in engineered cells and biocatalysis. Sequestration of enzymes and substrates would greatly increase reaction efficiency while also protecting engineered host cells from potentially toxic reaction intermediates. Several bacteria form protein-based polyhedral microcompartments which sequester functionally related enzymes and regulate their access to substrates and other small metabolites. Such bacterial microcompartments may be engineered into protein-based nano-bioreactors, provided that they can be assembled in a non-native host cell, and that heterologous enzymes and substrates can be targeted into the engineered compartments. Here, we report that recombinant expression of Salmonella enterica ethanolamine utilization (eut bacterial microcompartment shell proteins in E. coli results in the formation of polyhedral protein shells. Purified recombinant shells are morphologically similar to the native Eut microcompartments purified from S. enterica. Surprisingly, recombinant expression of only one of the shell proteins (EutS is sufficient and necessary for creating properly delimited compartments. Co-expression with EutS also facilitates the encapsulation of EGFP fused with a putative Eut shell-targeting signal sequence. We also demonstrate the functional localization of a heterologous enzyme (β-galactosidase targeted to the recombinant shells. Together our results provide proof-of-concept for the engineering of protein nano-compartments for biosynthesis and biocatalysis.

  10. POMSS配位化合物%Synthesis and Application of POMSS

    Institute of Scientific and Technical Information of China (English)

    李昂; 张春玲; 孙国恩; 牟建新

    2012-01-01

    The synthesis strategies, physical and chemical properties, as well as applications of polyhedral oligometallasilsesquioxanes(POMSS) have taken a remarkable leap in recent 20 years. It is still one of the research focuses at present. A rich chemistry of POMSS has developed with elements throughout the periodic table, that used widely as catalysts or silica-supported catalyst models and some other functional materials. In this paper, the developments and applications of POMSS are summarized and reviewed, especially for the status quo of incompletely condensed polyhedral oligomeric silsesquioxanes coordination chemistry.%近20年来,聚倍半硅氧烷金属配合物(POMSS)的合成、物理和化学性质以及应用,取得了飞跃式的发展,是当前的研究热点之一。其所包含的配位元素的种类几乎遍布整个元素周期表,并被广泛地应用于催化剂领域和其他功能材料领域。本文根据配位元素的特点对POMSS配合物进行了分类,并对其合成方法、发展及应用情况做了简单总结,最后对POMSS未来的研究前景进行了展望。

  11. Relevance of capsid structure in the buckling and maturation of spherical viruses

    International Nuclear Information System (INIS)

    The shape and mechanical properties of viral capsids play an important role in several biological processes during the virus life cycle. In particular, to become infective, many viruses require a maturation stage where the capsid undergoes a buckling transition, from an initial spherical procapsid into a final icosahedral faceted shell. Here we study, using a minimal physical model, how the capsid shape and the buckling transition depend on the triangulation number T and the icosahedral class P of the virus structure. We find that, for small shells, capsids with P = 1 are most likely to produce polyhedral shapes that minimize their energy and accumulated stress, whereas viruses with P = 3 prefer to remain spherical. For big capsids, all shells are more stable adopting an icosahedral shape, in agreement with continuum elastic theory. Moreover, spherical viruses show a buckling transition to polyhedral shells under expansion, in consonance with virus maturation. The resulting icosahedral shell is mechanically stiffer, tolerates larger expansions and withstands higher internal pressures before failing, which could explain why some dsDNA viruses, which rely on the pressurization of their genetic material to facilitate the infection, undergo a buckling transition. We emphasize that the results are general and could also be applied to non-biological systems. (paper)

  12. Constrained control of uncertain, time-varying, discrete-time systems an interpolation-based approach

    CERN Document Server

    Nguyen, Hoai-Nam

    2014-01-01

    A comprehensive development of interpolating control, this monograph demonstrates the reduced computational complexity of a ground-breaking technique compared with the established model predictive control. The text deals with the regulation problem for linear, time-invariant, discrete-time uncertain dynamical systems having polyhedral state and control constraints, with and without disturbances, and under state or output feedback. For output feedback a non-minimal state-space representation is used with old inputs and outputs as state variables. Constrained Control of Uncertain, Time-Varying, Discrete-time Systems details interpolating control in both its implicit and explicit forms. In the former at most two linear-programming or one quadratic-programming problem are solved on-line at each sampling instant to yield the value of the control variable. In the latter the control law is shown to be piecewise affine in the state, and so the state space is partitioned into polyhedral cells so that at each sampling ...

  13. Acoustic echoes reveal room shape.

    Science.gov (United States)

    Dokmanic, Ivan; Parhizkar, Reza; Walther, Andreas; Lu, Yue M; Vetterli, Martin

    2013-07-23

    Imagine that you are blindfolded inside an unknown room. You snap your fingers and listen to the room's response. Can you hear the shape of the room? Some people can do it naturally, but can we design computer algorithms that hear rooms? We show how to compute the shape of a convex polyhedral room from its response to a known sound, recorded by a few microphones. Geometric relationships between the arrival times of echoes enable us to "blindfoldedly" estimate the room geometry. This is achieved by exploiting the properties of Euclidean distance matrices. Furthermore, we show that under mild conditions, first-order echoes provide a unique description of convex polyhedral rooms. Our algorithm starts from the recorded impulse responses and proceeds by learning the correct assignment of echoes to walls. In contrast to earlier methods, the proposed algorithm reconstructs the full 3D geometry of the room from a single sound emission, and with an arbitrary geometry of the microphone array. As long as the microphones can hear the echoes, we can position them as we want. Besides answering a basic question about the inverse problem of room acoustics, our results find applications in areas such as architectural acoustics, indoor localization, virtual reality, and audio forensics. PMID:23776236

  14. Mimetic finite difference method

    Science.gov (United States)

    Lipnikov, Konstantin; Manzini, Gianmarco; Shashkov, Mikhail

    2014-01-01

    The mimetic finite difference (MFD) method mimics fundamental properties of mathematical and physical systems including conservation laws, symmetry and positivity of solutions, duality and self-adjointness of differential operators, and exact mathematical identities of the vector and tensor calculus. This article is the first comprehensive review of the 50-year long history of the mimetic methodology and describes in a systematic way the major mimetic ideas and their relevance to academic and real-life problems. The supporting applications include diffusion, electromagnetics, fluid flow, and Lagrangian hydrodynamics problems. The article provides enough details to build various discrete operators on unstructured polygonal and polyhedral meshes and summarizes the major convergence results for the mimetic approximations. Most of these theoretical results, which are presented here as lemmas, propositions and theorems, are either original or an extension of existing results to a more general formulation using polyhedral meshes. Finally, flexibility and extensibility of the mimetic methodology are shown by deriving higher-order approximations, enforcing discrete maximum principles for diffusion problems, and ensuring the numerical stability for saddle-point systems.

  15. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

    2015-11-17

    Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

  16. Support Shape Effect on the Catalytic Performance of Pt/CeO2 Nanostructures for Methanol Electrooxidation

    International Nuclear Information System (INIS)

    Highlights: • Polyhedral, cubic and rod-like nanosize CeO2 supported Pt catalysts were prepared. • Electrooxidation of methanol on different Pt/CeO2 catalysts was examined. • CeO2 nanorods supported Pt particles showed the highest electrocatalytic activity. • Support-shape-dependent catalytic activity of Pt/CeO2 was addressed. - Abstract: Polyhedral, cubic, and rod-like CeO2 nanostructures have been selectively synthesized and used as supports for Pt nanoparticles. The structures of Pt/CeO2, specially the exposed crystallographic facets of different CeO2 nanosupports, have been investigated by electron microscopy. A shape change induced variation of the exposed facets on CeO2 surface has been confirmed. In methanol electrooxidation, Pt/CeO2 particles have been found to acquire a generally improved and, more importantly, support-shape-dependent electrocatalytic activity. Pt nanoparticles earn the best activity on CeO2 nanorods while they gain the poorest activity on CeO2 nanopolyhedra. The result, indeed, reveals a fact that the {110} and {100} over {111} planes on ceria surface possess a superiority in improving the electrocatalytic performance of their supported Pt nanoparticles

  17. A seed-mediated approach to the morphology-controlled synthesis of bimetallic copper-platinum alloy nanoparticles with enhanced electrocatalytic performance for the methanol oxidation reaction

    Science.gov (United States)

    Han, Lin; Cui, Penglei; He, Hongyan; Liu, Hui; Peng, Zhijian; Yang, Jun

    2015-07-01

    Mastery over the morphology of nanomaterials usually enables control of their properties and enhancement of their usefulness for a given application. Herein, we report a seed-mediated approach for the fabrication of bimetallic copper-platinum (CuPt) alloy nanoparticles with different morphologies. This strategy involves the first synthesis of Cu seed particles with multiple twins, and subsequent nucleation and growth of Pt metal. Then upon the Cu/Pt molar ratios in the synthesis, the rapid interdiffusion of Cu and Pt atoms results in the formation of bimetallic CuPt alloy nanoparticles with polyhedral, stellated, or dendritic morphologies. It has been found that both the morphology and electronic coupling effect between Cu and Pt components have significant effect on the electrochemical property of the alloy particles. In particular, the dendritic CuPt alloy nanoparticles display the highest specific activity for methanol oxidation reaction (MOR) due to their abundant atomic steps, edges, and corner atoms in the dendritic structure, while the polyhedral CuPt alloy particles show best carbon monoxide (CO) tolerant behavior due to the strong electronic donation effect from Cu to Pt atoms.

  18. Na2TiGeO5: Crystal structure stability at low temperature and high pressure

    DEFF Research Database (Denmark)

    Waskowska, A.; Gerward, Leif; Olsen, J.S.;

    2008-01-01

    The temperature evolution of the lattice parameters measured from 295 to 125 K exhibits a small instability below T-c approximate to 278 K, indicating ferroelastic properties of Na2TiGeO5. The behavior is related to the specific crystal structure built of polyhedral layers with shared TiO5 pyramids...... and GeO4 tetrahedra, alternating with layers of Na+ cations. Antiparallel alignment of the short apical titanyl bond in adjacent rows of the polyhedral layer gives rise to spontaneous strain, when a distortion of the TiO5 groups occurs. Single-crystal structures determined at room temperature and 120 K......-axis. The structure distortion, however, is too small to allow any unambiguous determination of the symmetry-breaking effects. The bulk modulus and its pressure derivative have been determined as B-0 = 89(2) GPa and B'(0) = 4.0. A pressure-induced phase transformation takes place at P-c approximate to 12.5 GPa...

  19. Development of boronated tumor-seeking materials for application in neutron capture therapy of cancer

    International Nuclear Information System (INIS)

    Full text: At the present time the main field of application of boron compounds in medicine is Boron Neutron Capture Therapy (BNCT) of cancer. In this presentation the main principles of BNCT and main types of polyhedral boron compounds used for BNCT will be shown. The successful treatment of tumors by BNCT requires selective delivery of the boron moiety into the tumor cells. One of ways to solve this problem is attachment of boron fragment to different tumor-specific targeting molecules. Literature and our recent results on the preparation of novel boronated amino acids, carboranecarboxylic acids, a design of different conjugates of polyhedral boron compounds with tumor-seeking molecules, like porphyrins, phthalocyanines, nucleosides, carbohydrates, and lipids will be presented. Conjugates of natural porphyrins and phthalocyanines with carborane, closo-dodecaborate and cobalt bis(dicarbollide) were synthesized. The combination of these two fragments in one molecule makes these compounds potentially useful for both fluorescence diagnostics (FD) and BNCT of tumours. Boronated nucleosides are considered to be potential BNCT candidates because they can accumulate in the tumor cells. Thus, we have succeeded in preparation of the very first conjugates of closo-dodecaborate anion with one canonic nucleoside (thymidine)

  20. Thickness and clearance visualization based on distance field of 3D objects

    Directory of Open Access Journals (Sweden)

    Masatomo Inui

    2015-07-01

    Full Text Available This paper proposes a novel method for visualizing the thickness and clearance of 3D objects in a polyhedral representation. The proposed method uses the distance field of the objects in the visualization. A parallel algorithm is developed for constructing the distance field of polyhedral objects using the GPU. The distance between a voxel and the surface polygons of the model is computed many times in the distance field construction. Similar sets of polygons are usually selected as close polygons for close voxels. By using this spatial coherence, a parallel algorithm is designed to compute the distances between a cluster of close voxels and the polygons selected by the culling operation so that the fast shared memory mechanism of the GPU can be fully utilized. The thickness/clearance of the objects is visualized by distributing points on the visible surfaces of the objects and painting them with a unique color corresponding to the thickness/clearance values at those points. A modified ray casting method is developed for computing the thickness/clearance using the distance field of the objects. A system based on these algorithms can compute the distance field of complex objects within a few minutes for most cases. After the distance field construction, thickness/clearance visualization at a near interactive rate is achieved.

  1. Cell packing structures

    KAUST Repository

    Pottmann, Helmut

    2015-03-03

    This paper is an overview of architectural structures which are either composed of polyhedral cells or closely related to them. We introduce the concept of a support structure of such a polyhedral cell packing. It is formed by planar quads and obtained by connecting corresponding vertices in two combinatorially equivalent meshes whose corresponding edges are coplanar and thus determine planar quads. Since corresponding triangle meshes only yield trivial structures, we focus on support structures associated with quad meshes or hex-dominant meshes. For the quadrilateral case, we provide a short survey of recent research which reveals beautiful relations to discrete differential geometry. Those are essential for successfully initializing numerical optimization schemes for the computation of quad-based support structures. Hex-dominant structures may be designed via Voronoi tessellations, power diagrams, sphere packings and various extensions of these concepts. Apart from the obvious application as load-bearing structures, we illustrate here a new application to shading and indirect lighting. On a higher level, our work emphasizes the interplay between geometry, optimization, statics, and manufacturing, with the overall aim of combining form, function and fabrication into novel integrated design tools.

  2. Operational damage of steel 12Kh1MF steam superheater tubes

    International Nuclear Information System (INIS)

    The structure and mechanical properties of steel 12Kh1MF specimens are investigated after cyclic tests under conditions simulating operational regime of steam superheater tubes. It is revealed that in thermal barocycling a decrease of steel strength and a transition from trans crystalline to intercrystalline feature take place due to precipitation of complex carbides along grain boundaries. Complex carbide formation is resulted from the appearance of free carbon of decomposed carbon-containing organic impurities in a water coolant

  3. A Better Method for Evaluating Heavy Metal Water Pollution

    OpenAIRE

    Hering, Janet

    2002-01-01

    High concentrations of heavy metals, and even trace amounts of some, can be harmful to both plants and animals. The toxicity of heavy metal contamination, however, is highly dependent on the chemical form of the metal in question. Metals that are bound in particles or to organic (carbon-containing) compounds are less toxic than dissolved free ions, less toxic meaning that the metals are less readily available for uptake by marine organisms.

  4. Spectroscopic characterisation of novel materials for semiconductor device applications

    OpenAIRE

    Reid, Ian

    2007-01-01

    The thesis uses surface science techniques to characterise the chemical composition and electronic properties of a range of carbon containing materials which have application in advanced semiconductor fabrication. The initial focus was on investigating the properties ofcarbon-doped oxide (CDO) which is a low dielectric constant material and a leading candidate to replace silicon dioxide (SiOz) as an interlayer dielectric (ILD) in microprocessor fabrication. The work then progresses to determi...

  5. Formation of a Composite Based on Polyurethane with Carbon Nanotubes and Shungite

    Science.gov (United States)

    Komarov, F. F.; Krivosheev, R. M.; Ksenofontov, M. A.; Koltunovich, T.; Abdullin, Kh. A.; Ostrovskaya, L. E.; Togambaeva, A. K.

    2015-03-01

    Physicomechanical and electrophysical characteristics of a polyurethane composite doped with carbon-containing materials have been investigated. It has been found that the roughness of the sample's surface and also the porosity increase with the concentration of the dopant. Volt-ampere characteristics of composite materials point to the activated type of conductivity in these materials; however, at a temperature of nearly 340 K, the type of conductivity is changed. Also, the frequency dependence of the conductivity has been established.

  6. The discovery of fullerenes in the 1.85 billion-year-old Sudbury meteorite crater

    Energy Technology Data Exchange (ETDEWEB)

    Becker, L.; Bada, J.L. [Scripps Institution of Oceanography, La Jolla, CA (United States); Winans, R.E.; Hunt, J.E. [Argonne National Lab., IL (United States); Bunch, T.E. [National Aeronautics and Space Administration, Moffett Field, CA (United States). Ames Research Center; French, B.M. [National Aeronautics and Space Administration, Washington, DC (United States)

    1996-02-01

    Fullerenes (C{sub 60}, C{sub 70}) have been identified by laser time-of-flight and electron-ionization mass spectroscopy in rock samples (black tuff in the Onaping formation) from the crater. They were likely synthesized within the impact plume from carbon contained in the meteorite. The isotopic ratios suggest {sup 13}C enrichment. They are associated with sulfur which may have protected them. This is the largest known deposit of naturally occurring fullerenes.

  7. Coral reef invertebrate microbiomes correlate with the presence of photosymbionts

    OpenAIRE

    Bourne, David G.; Dennis, Paul G.; Uthicke, Sven; Soo, Rochelle M; Tyson, Gene W; Nicole WEBSTER

    2013-01-01

    Coral reefs provide habitat for an array of marine invertebrates that host symbiotic microbiomes. Photosynthetic symbionts including Symbiodinium dinoflagellates and diatoms potentially influence the diversity of their host-associated microbiomes by releasing carbon-containing photosynthates and other organic compounds that fuel microbial metabolism. Here we used 16S ribosomal RNA (rRNA) gene amplicon pyrosequencing to characterise the microbiomes of 11 common Great Barrier Reef marine invert...

  8. Bioorganic Chemistry. A Natural Reunion of the Physical and Life Sciences

    OpenAIRE

    Poulter, C. Dale

    2009-01-01

    Organic substances were conceived as those found in living organisms. Although the definition was soon broadened to include all carbon-containing compounds, naturally occurring molecules have always held a special fascination for organic chemists. From these beginnings, molecules from nature were indespensible tools as generations of organic chemists developed new techniques for determining structures, analyzed the mechanisms of reactions, explored the effects conformation and stereochemistry...

  9. Polypyrrole-derived mesoporous nitrogen-doped carbons with intrinsic catalytic activity in the oxygen reduction reaction

    OpenAIRE

    Sevilla Solís, Marta; Yu, Linghui; Fellinger, Tim Patrick; Fuertes Arias, Antonio Benito; Titirici, Maria-Magdalena

    2013-01-01

    [EN] N-doped mesoporous carbons containing small amounts of graphitic carbon have been successfully prepared using the nanocasting technique. Polypyrrole was used as N-dopant carbon precursor and SBA-15 or silica xerogel as templates. Graphitic carbon domains provide a good electronic conductivity of up to 0.33 S cm−1, a necessary property for electrochemical applications, while a mesoporous structure reduces mass transport limitations. These characteristics are further combined with a high N...

  10. Catalytic carbon deposition on 3-dimensional carbon fibre supports

    OpenAIRE

    Thornton, Matthew James

    2005-01-01

    Catalytic carbon deposition reactions, using methane, ethane or synthetic natural gas (1.8 vol. % propane, 6.7 vol. % ethane and balance methane) as the carbon-containing gas feedstock with or without the addition of hydrogen, have been investigated over nickel, cobalt and iron catalysts supported on 3-dimensional carbon fibre supports, using both a horizontal tube furnace and an isothermal, isobaric induction furnace. The transition metal catalysts were prepared by impregnating 3-dimens...

  11. Data on collisions of hydrogen atoms and ions with atoms and molecules, (1)

    International Nuclear Information System (INIS)

    This report presents a compilation of the experimental data on cross sections for charge transfer of H, H+ and H- with H2, N2, O2, H2O, C and carbon containing molecules. A survey has been made systematically of the literature up to the middle of 1982. The cross sections are given as a function of projectile energy in graphs and tables; a list of references is also attached. (author)

  12. Composition, Property Characterization and Application of Agricultural and Forest Biomass Carbon

    OpenAIRE

    Lei, Chunsheng; Zhu, Xiaofeng; Zhou, Meicheng; Liang, Yuting; Zhang, Feng'e

    2014-01-01

    We analyzed the compositions and basic properties of agricultural and forest biomass carbon, and used the pot method to study the influence of such element on the remediation of contaminated soils and growth of crops. Results show that agricultural and forest biomass carbon contains various nutrients that are necessary for crop growth, high specific surface area, and pore structure development. Cotton stalk charcoal can reduce bioavailability of Cadmium (Cd) in soil. Under mild Cd pollution, ...

  13. Impurity-defect structure of anodic aluminum oxide produced by two-sided anodizing in tartaric acid

    Science.gov (United States)

    Chernyakova, K. V.; Vrublevsky, I. A.; Ivanovskaya, M. I.; Kotsikau, D. A.

    2012-03-01

    Porous aluminum oxide is prepared in a 0.4 M aqueous solution of tartaric acid by two-sided anodizing. Fourier Transform IR spectroscopy (FTIR) data reveal the presence, in the alumina, of unoxidized tartarate ions, as well as products of their partial (radical organic products and CO) and complete (CO2) oxidation. Carboxylate ions and elemental carbon contained in the anodic oxide impart a gray color to the films.

  14. Combustion method for producing fullerenes

    Science.gov (United States)

    Howard, Jack B.; McKinnon, J. Thomas

    1993-01-01

    A method for synthesizing fullerenes in flames is provided. Fullerenes are prepared by burning carbon-containing compounds in a flame and collecting the condensibles. The condensibles contain the desired fullerenes. Fullerene yields can be optimized and fullerene composition can be selectively varied. Fullerene yields and compositions are determined by selectively controlling flame conditions and parameters such as C/O ratio, pressure, temperature, residence time, diluent concentration and gas velocity.

  15. Studies in sublimation of tungsten single crystal (110) face and the influence of carbon

    Energy Technology Data Exchange (ETDEWEB)

    Dekhtyar, I.Ya.; Kolesnik, V.M.; Patoka, V.I.; Silant' ev, V.I.

    1975-12-01

    Evaporation of the tungsten single crystal (110) face was studied in ultrahigh vacuum (better than 1.10/sup -9/ Torr) using the Langmuir method. The influence of carbon impurities on the evaporation parameters was found out and carbon is shown to increase the sublimation energy by 25 kcal. The data obtained show that the parameters of tungsten evaporation available in literature should be related to carbon-containing materials.

  16. Mapping organic carbon stocks in eucalyptus plantations of the central highlands of Madagascar : a multiple regression approach

    OpenAIRE

    Razakamanarivo, R. H.; Grinand, Clovis; Razafindrakoto, M. A.; Bernoux, Martial; Albrecht, Alain

    2011-01-01

    Recent concerns about global warming have resulted in more concerted studies on quantification and modeling of carbon (C) storage in different ecosystems. The aim of this study was to assess and map the carbon stocks in above (ABG), below-ground (BLG) biomass and soil organic carbon contained in the 30 centimeter top-layer (SOC) in coppices of eucalyptus plantations in the central highlands of Madagascar in an area of 1590 ha. Relationships between C stock and various biophysical (stool or sh...

  17. Octadecahedral and dodecahedral iron nanoparticles: An atomistic simulation on stability and shape evolutions

    Science.gov (United States)

    Wu, Yu-Ning; Huang, Rao; Zeng, Xiang-Ming; Wen, Yu-Hua

    2016-02-01

    Fe nanoparticles have attracted great interest due to their potent magnetic and catalytic properties which strongly depend on the structures and morphologies. In this article, molecular dynamic simulations were employed to investigate structural and thermal stabilities of body-centered cubic Fe nanoparticles with octadecahedral, dodecahedral and spherical shapes. Size-dependent structural stability was firstly examined. Subsequently, computer simulations on the heating process of octadecahedral Fe nanoparticle discovered that {100} facets premelt earlier than {110} ones. As a result, the dodecahedral nanoparticle enclosed by {110} facets exhibited a better thermal stability than the octadecahedral one terminated by both {110} and {100} facets. Nevertheless, it was found that the octadecahedron presented a better shape stability than the dodecahedron by monitoring the shape factor and statistical radius during continuous heating. This study provides a significant insight not only into the experimental preparation of polyhedral Fe nanoparticles but also into their utilization in high-temperature environments.

  18. New techniques in 3D scalar and vector field visualization

    International Nuclear Information System (INIS)

    At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ''splatting'' scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ''flow volume'' of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity

  19. Optical Tomography of Polydisperse Dry Foam

    Science.gov (United States)

    Chieco, Anthony; Feitosa, Klebert; Korda, P. T.; Roth, A. E.; Durian, D. J.

    2011-11-01

    Dry foam is a disordered packing of bubbles that distort into familiar polyhedral shapes. We have implemented a method that uses optical axial tomography to reconstruct the internal structure of a dry foam in three dimensions. The technique consists of taking a series of photographs of the dry foam against a uniformly illuminated background at successive angles. By summing the projections we create images of the cross section of the foam and analyze them to locate the Plateau borders and vertices. The vertices are then connected according to Plateau's rules to reconstruct the internal structure of the foam. Using this technique we are able to visualize a large number of bubbles of real 3D foams and obtain statistics of faces and edges. We gratefully acknowledge support from DOD-ASSURE/NSF-REU grant # DMR-0851367.

  20. Digital Reconstruction of 3D Polydisperse Dry Foam

    Science.gov (United States)

    Chieco, A.; Feitosa, K.; Roth, A. E.; Korda, P. T.; Durian, D. J.

    2012-02-01

    Dry foam is a disordered packing of bubbles that distort into familiar polyhedral shapes. We have implemented a method that uses optical axial tomography to reconstruct the internal structure of a dry foam in three dimensions. The technique consists of taking a series of photographs of the dry foam against a uniformly illuminated background at successive angles. By summing the projections we create images of the foam cross section. Image analysis of the cross sections allows us to locate Plateau borders and vertices. The vertices are then connected according to Plateau's rules to reconstruct the internal structure of the foam. Using this technique we are able to visualize a large number of bubbles of real 3D foams and obtain statistics of faces and edges.