WorldWideScience

Sample records for strongly anisotropic adsorbate

  1. Coefficient adaptive triangulation for strongly anisotropic problems

    Energy Technology Data Exchange (ETDEWEB)

    D`Azevedo, E.F.; Romine, C.H.; Donato, J.M.

    1996-01-01

    Second order elliptic partial differential equations arise in many important applications, including flow through porous media, heat conduction, the distribution of electrical or magnetic potential. The prototype is the Laplace problem, which in discrete form produces a coefficient matrix that is relatively easy to solve in a regular domain. However, the presence of anisotropy produces a matrix whose condition number is increased, making the resulting linear system more difficult to solve. In this work, we take the anisotropy into account in the discretization by mapping each anisotropic region into a ``stretched`` coordinate space in which the anisotropy is removed. The region is then uniformly triangulated, and the resulting triangulation mapped back to the original space. The effect is to generate long slender triangles that are oriented in the direction of ``preferred flow.`` Slender triangles are generally regarded as numerically undesirable since they tend to cause poor conditioning; however, our triangulation has the effect of producing effective isotropy, thus improving the condition number of the resulting coefficient matrix.

  2. 2D seismic reflection tomography in strongly anisotropic media

    Science.gov (United States)

    Huang, Guangnan; Zhou, Bing; Li, Hongxi; Zhang, Hua; Li, Zelin

    2014-12-01

    Seismic traveltime tomography is an effective method to reconstruct underground anisotropic parameters. Currently, most anisotropic tomographic methods were developed under the assumption of weak anisotropy. The tomographic method proposed here can be implemented for imaging subsurface targets in strongly anisotropic media with a known tilted symmetry axis, since the adopted ray tracing method is suitable for anisotropic media with arbitrary degree. There are three kinds of reflection waves (qP, qSV and qSH waves) that were separately used to invert the blocky abnormal body model. The reflection traveltime tomographiy is developed here because a surface observation system is the most economical and practical way compared with crosswell and VSP. The numerical examples show that the traveltimes of qP reflection wave have inverted parameters {{c}11},{{c}13},{{c}33} \\text{and} {{c}44} successfully. Traveltimes of qSV reflection wave have inverted parameters {{c}11},{{c}33} \\text{and} {{c}44} successfully, with the exception of the {{c}13}, since it is less sensitive than other parameters. Traveltimes of qSH reflection wave also have inverted parameters {{c}44} \\text{and} {{c}66} successfully. In addition, we find that the velocity sensitivity functions (derivatives of phase velocity with respect to elastic moduli parameters) and raypath illuminating angles have a great influence on the qualities of tomograms according to the inversion of theoretical models. Finally, the numerical examples confirm that the reflection traveltime tomography can be applied to invert strongly anisotropic models.

  3. Theory of Spin Waves in Strongly Anisotropic Magnets

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Cooke, J. F.

    1976-01-01

    A new infinite-order perturbation approach to the theory of spin waves in strongly anisotropic magnets is introduced. The system is transformed into one with effective two-ion anisotropy and considerably reduced ground-state corrections. A general expression for the spin-wave energy, valid to any...

  4. Membrane-mediated interaction between strongly anisotropic protein scaffolds.

    Directory of Open Access Journals (Sweden)

    Yonatan Schweitzer

    2015-02-01

    Full Text Available Specialized proteins serve as scaffolds sculpting strongly curved membranes of intracellular organelles. Effective membrane shaping requires segregation of these proteins into domains and is, therefore, critically dependent on the protein-protein interaction. Interactions mediated by membrane elastic deformations have been extensively analyzed within approximations of large inter-protein distances, small extents of the protein-mediated membrane bending and small deviations of the protein shapes from isotropic spherical segments. At the same time, important classes of the realistic membrane-shaping proteins have strongly elongated shapes with large and highly anisotropic curvature. Here we investigated, computationally, the membrane mediated interaction between proteins or protein oligomers representing membrane scaffolds with strongly anisotropic curvature, and addressed, quantitatively, a specific case of the scaffold geometrical parameters characterizing BAR domains, which are crucial for membrane shaping in endocytosis. In addition to the previously analyzed contributions to the interaction, we considered a repulsive force stemming from the entropy of the scaffold orientation. We computed this interaction to be of the same order of magnitude as the well-known attractive force related to the entropy of membrane undulations. We demonstrated the scaffold shape anisotropy to cause a mutual aligning of the scaffolds and to generate a strong attractive interaction bringing the scaffolds close to each other to equilibrium distances much smaller than the scaffold size. We computed the energy of interaction between scaffolds of a realistic geometry to constitute tens of kBT, which guarantees a robust segregation of the scaffolds into domains.

  5. Thermodynamics and instabilities of a strongly coupled anisotropic plasma

    Science.gov (United States)

    Mateos, David; Trancanelli, Diego

    2011-07-01

    We extend our analysis of a IIB supergravity solution dual to a spatially anisotropic finite-temperature mathcal{N} = 4 super Yang-Mills plasma. The solution is static, possesses an anisotropic horizon, and is completely regular. The full geometry can be viewed as a renormalization group flow from an AdS geometry in the ultraviolet to a Lifshitz-like geometry in the infrared. The anisotropy can be equivalently understood as resulting from a position-dependent θ-term or from a non-zero number density of dissolved D7-branes. The holographic stress tensor is conserved and anisotropic. The presence of a conformal anomaly plays an important role in the thermodynamics. The phase diagram exhibits homogeneous and inhomogeneous (i.e. mixed) phases. In some regions the homogeneous phase displays instabilities reminiscent of those of weakly coupled plasmas. We comment on similarities with QCD at finite baryon density and with the phenomenon of cavitation.

  6. Strongly anisotropic spin-orbit splitting in a two-dimensional electron gas

    DEFF Research Database (Denmark)

    Michiardi, Matteo; Bianchi, Marco; Dendzik, Maciej

    2015-01-01

    Near-surface two-dimensional electron gases on the topological insulator Bi$_2$Te$_2$Se are induced by electron doping and studied by angle-resolved photoemission spectroscopy. A pronounced spin-orbit splitting is observed for these states. The $k$-dependent splitting is strongly anisotropic...

  7. Violation of the Holographic Viscosity Bound in a Strongly Coupled Anisotropic Plasma

    Science.gov (United States)

    Rebhan, Anton; Steineder, Dominik

    2012-01-01

    We study the conductivity and shear viscosity tensors of a strongly coupled N=4 super-Yang-Mills plasma which is kept anisotropic by a θ parameter that depends linearly on one of the spatial dimensions. Its holographic dual is given by an anisotropic axion-dilaton-gravity background and has recently been proposed by Mateos and Trancanelli as a model for the preequilibrium stage of quark-gluon plasma in heavy-ion collisions. By applying the membrane paradigm which we also check by numerical evaluation of Kubo formula and lowest lying quasinormal modes, we find that the shear viscosity purely transverse to the direction of anisotropy saturates the holographic viscosity bound, whereas longitudinal shear viscosities are smaller, providing the first such example not involving higher-derivative theories of gravity and, more importantly, with fully known gauge-gravity correspondence.

  8. Holographic RG flow of the shear viscosity to entropy density ratio in strongly coupled anisotropic plasma

    Science.gov (United States)

    Mamo, Kiminad A.

    2012-10-01

    We study holographic RG flow of the shear viscosity tensor of anisotropic, strongly coupled {N}=4 super-Yang-Mills plasma by using its type IIB supergravity dual in anisotropic bulk spacetime. We find that the shear viscosity tensor has three independent components in the anisotropic bulk spacetime away from the boundary, and one of the components has a non-trivial RG flow while the other two have a trivial one. For the component of the shear viscosity tensor with non-trivial RG flow, we derive its RG flow equation, and solve the equation analytically to second order in the anisotropy parameter a. We derive the RG equation using the equation of motion, holographic Wilsonian RG method, and Kubo's formula. All methods give the same result. Solving the equation, we find that the ratio of the component of the shear viscosity tensor to entropy density η /s flows from above 1/{4π } the horizon (IR) to below 1/{4π } the boundary (UV) where it violates the holographic shear viscosity (Kovtun-Son-Starinets) bound and where it agrees with the other longitudinal component.

  9. Drag force in strongly coupled, anisotropic plasma at finite chemical potential

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Somdeb; Haque, Najmul [Theory Division, Saha Institute of Nuclear Physics,1/AF Bidhannagar, Kolkata-700 064 (India)

    2014-12-30

    We employ methods of gauge/string duality to analyze the drag force on a heavy quark moving through a strongly coupled, anisotropic N=4,SU(N) super Yang-Mills plasma in the presence of a finite U(1) chemical potential. We present numerical results valid for any value of the anisotropy parameter and the U(1) charge density and arbitrary direction of the quark velocity with respect to the direction of anisotropy. In the small anisotropy limit we are also able to furnish analytical results.

  10. Adsorbate-mediated strong metal-support interactions in oxide-supported Rh catalysts.

    Science.gov (United States)

    Matsubu, John C; Zhang, Shuyi; DeRita, Leo; Marinkovic, Nebojsa S; Chen, Jingguang G; Graham, George W; Pan, Xiaoqing; Christopher, Phillip

    2017-02-01

    The optimization of supported metal catalysts predominantly focuses on engineering the metal site, for which physical insights based on extensive theoretical and experimental contributions have enabled the rational design of active sites. Although it is well known that supports can influence the catalytic properties of metals, insights into how metal-support interactions can be exploited to optimize metal active-site properties are lacking. Here we utilize in situ spectroscopy and microscopy to identify and characterize a support effect in oxide-supported heterogeneous Rh catalysts. This effect is characterized by strongly bound adsorbates (HCO x ) on reducible oxide supports (TiO 2 and Nb 2 O 5 ) that induce oxygen-vacancy formation in the support and cause HCO x -functionalized encapsulation of Rh nanoparticles by the support. The encapsulation layer is permeable to reactants, stable under the reaction conditions and strongly influences the catalytic properties of Rh, which enables rational and dynamic tuning of CO 2 -reduction selectivity.

  11. Analytical modeling of equilibrium of strongly anisotropic plasma in tokamaks and stellarators

    Energy Technology Data Exchange (ETDEWEB)

    Lepikhin, N. D.; Pustovitov, V. D., E-mail: pustovit@nfi.kiae.ru [National Research Centre Kurchatov Institute (Russian Federation)

    2013-08-15

    Theoretical analysis of equilibrium of anisotropic plasma in tokamaks and stellarators is presented. The anisotropy is assumed strong, which includes the cases with essentially nonuniform distributions of plasma pressure on magnetic surfaces. Such distributions can arise at neutral beam injection or at ion cyclotron resonance heating. Then the known generalizations of the standard theory of plasma equilibrium that treat p{sub ‖} and p{sub ⊥} (parallel and perpendicular plasma pressures) as almost constant on magnetic surfaces are not applicable anymore. Explicit analytical prescriptions of the profiles of p{sub ‖} and p{sub ⊥} are proposed that allow modeling of the anisotropic plasma equilibrium even with large ratios of p{sub ‖}/p{sub ⊥} or p{sub ⊥}/p{sub ‖}. A method for deriving the equation for the Shafranov shift is proposed that does not require introduction of the flux coordinates and calculation of the metric tensor. It is shown that for p{sub ⊥} with nonuniformity described by a single poloidal harmonic, the equation for the Shafranov shift coincides with a known one derived earlier for almost constant p{sub ⊥} on a magnetic surface. This does not happen in the other more complex case.

  12. Variation of the critical slab thickness with the degree of strongly anisotropic scattering in one-speed neutron transport theory

    International Nuclear Information System (INIS)

    Yildiz, C.

    1998-01-01

    The critical slab problem is studied in one-speed neutron transport theory using a linearly anisotropic kernel which combines forward and backward scattering. It is shown that, the recently observed non-monotonic variation of the thickness also exists in this strongly anisotropic case. In addition, the influence of the linear anisotropy on the critical thickness is analysed in detail. Numerical analysis for the critical thickness are performed using the spherical harmonics method and results are tabulated for selected illustrative cases as a function of different degrees of anisotropic scattering. Finally, some results are discussed and compared with those already obtained by other methods, the agreement is satisfactory. The spherical harmonic method gives generally accurate results in one dimensional geometry, and it is very suitable for the numerical solution of the neutron transport equation with linearly anisotropic scattering

  13. Spin quenching assisted by a strongly anisotropic compression behavior in MnP

    Energy Technology Data Exchange (ETDEWEB)

    Han, Fei; Wang, Di; Wang, Yonggang; Li, Nana; Bao, Jin-Ke; Li, Bing; Botana, Antia S.; Xiao, Yuming; Chow, Paul; Chung, Duck Young; Chen, Jiuhua; Wan, Xiangang; Kanatzidis, Mercouri G.; Yang, Wenge; Mao, Ho-Kwang

    2018-02-01

    We studied the crystal structure and spin state of MnP under high pressure with synchrotron X-ray diffraction and X-ray emission spectroscopy. MnP has an exceedingly strong anisotropy in compressibility, with the primary compressible direction along the b axis of the Pnma structure. X-ray emission spectroscopy reveals a pressure-driven quenching of the spin state in MnP. First-principles calculations suggest that the strongly anisotropic compression behavior significantly enhances the dispersion of the Mn d-orbitals and the splitting of the d-orbital levels compared to the hypothetical isotropic compression behavior. Thus, we propose spin quenching results mainly from the significant enhancement of the itinerancy of d electrons and partly from spin rearrangement occurring in the split d-orbital levels near the Fermi level. This explains the fast suppression of magnetic ordering in MnP under high pressure. The spin quenching lags behind the occurrence of superconductivity at ~8 GPa implying that spin fluctuations govern the electron pairing for superconductivity.

  14. Directed emission of CdSe nanoplatelets originating from strongly anisotropic 2D electronic structure

    Science.gov (United States)

    Scott, Riccardo; Heckmann, Jan; Prudnikau, Anatol V.; Antanovich, Artsiom; Mikhailov, Aleksandr; Owschimikow, Nina; Artemyev, Mikhail; Climente, Juan I.; Woggon, Ulrike; Grosse, Nicolai B.; Achtstein, Alexander W.

    2017-12-01

    Intrinsically directional light emitters are potentially important for applications in photonics including lasing and energy-efficient display technology. Here, we propose a new route to overcome intrinsic efficiency limitations in light-emitting devices by studying a CdSe nanoplatelets monolayer that exhibits strongly anisotropic, directed photoluminescence. Analysis of the two-dimensional k-space distribution reveals the underlying internal transition dipole distribution. The observed directed emission is related to the anisotropy of the electronic Bloch states governing the exciton transition dipole moment and forming a bright plane. The strongly directed emission perpendicular to the platelet is further enhanced by the optical local density of states and local fields. In contrast to the emission directionality, the off-resonant absorption into the energetically higher 2D-continuum of states is isotropic. These contrasting optical properties make the oriented CdSe nanoplatelets, or superstructures of parallel-oriented platelets, an interesting and potentially useful class of semiconductor-based emitters.

  15. Anisotropic, lightweight, strong, and super thermally insulating nanowood with naturally aligned nanocellulose

    Science.gov (United States)

    Li, Tian; Song, Jianwei; Zhao, Xinpeng; Yang, Zhi; Pastel, Glenn; Xu, Shaomao; Jia, Chao; Dai, Jiaqi; Chen, Chaoji; Gong, Amy; Jiang, Feng; Yao, Yonggang; Fan, Tianzhu; Yang, Bao; Wågberg, Lars; Yang, Ronggui; Hu, Liangbing

    2018-01-01

    There has been a growing interest in thermal management materials due to the prevailing energy challenges and unfulfilled needs for thermal insulation applications. We demonstrate the exceptional thermal management capabilities of a large-scale, hierarchal alignment of cellulose nanofibrils directly fabricated from wood, hereafter referred to as nanowood. Nanowood exhibits anisotropic thermal properties with an extremely low thermal conductivity of 0.03 W/m·K in the transverse direction (perpendicular to the nanofibrils) and approximately two times higher thermal conductivity of 0.06 W/m·K in the axial direction due to the hierarchically aligned nanofibrils within the highly porous backbone. The anisotropy of the thermal conductivity enables efficient thermal dissipation along the axial direction, thereby preventing local overheating on the illuminated side while yielding improved thermal insulation along the backside that cannot be obtained with isotropic thermal insulators. The nanowood also shows a low emissivity of thermal energy. Moreover, the nanowood is lightweight yet strong, owing to the effective bonding between the aligned cellulose nanofibrils with a high compressive strength of 13 MPa in the axial direction and 20 MPa in the transverse direction at 75% strain, which exceeds other thermal insulation materials, such as silica and polymer aerogels, Styrofoam, and wool. The excellent thermal management, abundance, biodegradability, high mechanical strength, low mass density, and manufacturing scalability of the nanowood make this material highly attractive for practical thermal insulation applications. PMID:29536048

  16. Accurate and balanced anisotropic Gaussian type orbital basis sets for atoms in strong magnetic fields

    Science.gov (United States)

    Zhu, Wuming; Trickey, S. B.

    2017-12-01

    In high magnetic field calculations, anisotropic Gaussian type orbital (AGTO) basis functions are capable of reconciling the competing demands of the spherically symmetric Coulombic interaction and cylindrical magnetic (B field) confinement. However, the best available a priori procedure for composing highly accurate AGTO sets for atoms in a strong B field [W. Zhu et al., Phys. Rev. A 90, 022504 (2014)] yields very large basis sets. Their size is problematical for use in any calculation with unfavorable computational cost scaling. Here we provide an alternative constructive procedure. It is based upon analysis of the underlying physics of atoms in B fields that allow identification of several principles for the construction of AGTO basis sets. Aided by numerical optimization and parameter fitting, followed by fine tuning of fitting parameters, we devise formulae for generating accurate AGTO basis sets in an arbitrary B field. For the hydrogen iso-electronic sequence, a set depends on B field strength, nuclear charge, and orbital quantum numbers. For multi-electron systems, the basis set formulae also include adjustment to account for orbital occupations. Tests of the new basis sets for atoms H through C (1 ≤ Z ≤ 6) and ions Li+, Be+, and B+, in a wide B field range (0 ≤ B ≤ 2000 a.u.), show an accuracy better than a few μhartree for single-electron systems and a few hundredths to a few mHs for multi-electron atoms. The relative errors are similar for different atoms and ions in a large B field range, from a few to a couple of tens of millionths, thereby confirming rather uniform accuracy across the nuclear charge Z and B field strength values. Residual basis set errors are two to three orders of magnitude smaller than the electronic correlation energies in multi-electron atoms, a signal of the usefulness of the new AGTO basis sets in correlated wavefunction or density functional calculations for atomic and molecular systems in an external strong B field.

  17. Accurate and balanced anisotropic Gaussian type orbital basis sets for atoms in strong magnetic fields.

    Science.gov (United States)

    Zhu, Wuming; Trickey, S B

    2017-12-28

    In high magnetic field calculations, anisotropic Gaussian type orbital (AGTO) basis functions are capable of reconciling the competing demands of the spherically symmetric Coulombic interaction and cylindrical magnetic (B field) confinement. However, the best available a priori procedure for composing highly accurate AGTO sets for atoms in a strong B field [W. Zhu et al., Phys. Rev. A 90, 022504 (2014)] yields very large basis sets. Their size is problematical for use in any calculation with unfavorable computational cost scaling. Here we provide an alternative constructive procedure. It is based upon analysis of the underlying physics of atoms in B fields that allow identification of several principles for the construction of AGTO basis sets. Aided by numerical optimization and parameter fitting, followed by fine tuning of fitting parameters, we devise formulae for generating accurate AGTO basis sets in an arbitrary B field. For the hydrogen iso-electronic sequence, a set depends on B field strength, nuclear charge, and orbital quantum numbers. For multi-electron systems, the basis set formulae also include adjustment to account for orbital occupations. Tests of the new basis sets for atoms H through C (1 ≤ Z ≤ 6) and ions Li + , Be + , and B + , in a wide B field range (0 ≤ B ≤ 2000 a.u.), show an accuracy better than a few μhartree for single-electron systems and a few hundredths to a few mHs for multi-electron atoms. The relative errors are similar for different atoms and ions in a large B field range, from a few to a couple of tens of millionths, thereby confirming rather uniform accuracy across the nuclear charge Z and B field strength values. Residual basis set errors are two to three orders of magnitude smaller than the electronic correlation energies in multi-electron atoms, a signal of the usefulness of the new AGTO basis sets in correlated wavefunction or density functional calculations for atomic and molecular systems in an external strong B

  18. Layered Black Phosphorus: Strongly Anisotropic Magnetic, Electronic, and Electron-Transfer Properties.

    Science.gov (United States)

    Sofer, Zdeněk; Sedmidubský, David; Huber, Štěpán; Luxa, Jan; Bouša, Daniel; Boothroyd, Chris; Pumera, Martin

    2016-03-01

    Layered elemental materials, such as black phosphorus, exhibit unique properties originating from their highly anisotropic layered structure. The results presented herein demonstrate an anomalous anisotropy for the electrical, magnetic, and electrochemical properties of black phosphorus. It is shown that heterogeneous electron transfer from black phosphorus to outer- and inner-sphere molecular probes is highly anisotropic. The electron-transfer rates differ at the basal and edge planes. These unusual properties were interpreted by means of calculations, manifesting the metallic character of the edge planes as compared to the semiconducting properties of the basal plane. This indicates that black phosphorus belongs to a group of materials known as topological insulators. Consequently, these effects render the magnetic properties highly anisotropic, as both diamagnetic and paramagnetic behavior can be observed depending on the orientation in the magnetic field. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Analytical solutions by squeezing to the anisotropic Rabi model in the nonperturbative deep-strong-coupling regime

    Science.gov (United States)

    Zhang, Yu-Yu; Chen, Xiang-You

    2017-12-01

    An unexplored nonperturbative deep strong coupling (npDSC) achieved in superconducting circuits has been studied in the anisotropic Rabi model by the generalized squeezing rotating-wave approximation. Energy levels are evaluated analytically from the reformulated Hamiltonian and agree well with numerical ones in a wide range of coupling strength. Such improvement ascribes to deformation effects in the displaced-squeezed state presented by the squeezed momentum variance, which are omitted in previous displaced states. The atom population dynamics confirms the validity of our approach for the npDSC strength. Our approach offers the possibility to explore interesting phenomena analytically in the npDSC regime in qubit-oscillator experiments.

  20. Magnetic-field dependence of strongly anisotropic spin reorientation transition in NdFeO3: a terahertz study.

    Science.gov (United States)

    Jiang, Junjie; Song, Gaibei; Wang, Dongyang; Jin, Zuanming; Tian, Zhen; Lin, Xian; Han, Jiaguang; Ma, Guohong; Cao, Shixun; Cheng, Zhenxiang

    2016-03-23

    One of the biggest challenges in spintronics is finding how to switch the magnetization of a material. One way of the spin switching is the spin reorientation transition (SRT), a switching of macroscopic magnetization rotated by 90°. The macroscopic magnetization in a NdFeO3 single crystal rotates from Γ4 to Γ2 via Γ24 as the temperature is decreased from 170 to 100 K, while it can be switched back to Γ4 again by increasing the temperature. However, the precise roles of the magnetic-field induced SRT are still unclear. By using terahertz time-domain spectroscopy (THz-TDS), here, we show that the magnetic-field induced SRT between Γ4 and Γ2 is strongly anisotropic, depending on the direction of the applied magnetic field. Our experimental results are well interpreted by the anisotropy of rare-earth Nd(3+) ion. Furthermore, we find that the critical magnetic-field required for SRT can be modified by changing the temperature. Our study suggests that the anisotropic SRT in NdFeO3 single crystal provides a platform to facilitate the potential applications in robust spin memory devices.

  1. Energy transfer in anisotropic systems: A. Excitation migration in substitutionally disordered one-dimensional solids. B. The spectroscopy of molecules adsorbed on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zwemer, D.A.

    1978-11-01

    The energy and dynamics of excited states in a variety of anisotropic environments, including isotopically and chemically mixed crystals and molecular overlayers adsorbed on a nickel (111) surface, are investigated. The relationship between local and long-range structure and spectroscopic properties is explored. A theory for energy transfer in substitutionally disordered solids is presented. Explicit expressions for the ''diffusion'' coefficients and the energy partitioning ratios in binary systems are derived. Energy transfer between localized states is found to be facilitated by concurrent tunnelling and thermal promotion. Experimental results for triplet energy partitioning between mobile and stationary trap states as a function of mobile trap concentration in the ternary d/sub 2/-1,2,4,5-tetrachlorobenzene--h/sub 2/-1,2,4,5-tetrachlorobenzene--pyrazine system are analyzed. It is shown that both tunnelling and thermal detrapping contribute to triplet exciton mobility below 4.2 K. Singlet exciton migration makes an important contribution to trap equilibration before intersystem crossing to the triplet manifold. Spin coherence experiments are used to determine the energy level structure, physical geometry, and exciton dynamics of a series of impurity-induced traps in 1,2,4,5-tetrachlorobenzene. The uv spectra of pyrazine, pyridine, and naphthalene adsorbed on a nickel single crystal (111) surface are measured by spectroscopic ellipsometry at low temperatures. The excited electronic and vibronic energy levels measured are similar to bulk molecular crystal values, but pyrazine and pyridine show small, but significant deviations. The ordering of molecular overlays is observed spectroscopically and information about overlayer crystal structure is deduced. 148 references, 48 figures, 5 tables.

  2. Anisotropic shear viscosity of a strongly coupled non-Abelian plasma from magnetic branes

    Science.gov (United States)

    Critelli, R.; Finazzo, S. I.; Zaniboni, M.; Noronha, J.

    2014-09-01

    Recent estimates for the electromagnetic fields produced in the early stages of noncentral ultrarelativistic heavy ion collisions indicate the presence of magnetic fields B ˜O(0.1-15mπ2), where mπ is the pion mass. It is then of special interest to study the effects of strong (Abelian) magnetic fields on the transport coefficients of strongly coupled non-Abelian plasmas, such as the quark-gluon plasma formed in heavy ion collisions. In this paper we study the anisotropy in the shear viscosity induced by an external magnetic field in a strongly coupled N =4 super Yang-Mills (SYM) plasma. Due to the spatial anisotropy created by the magnetic field, the most general viscosity tensor of a magnetized plasma has five shear viscosity coefficients and two bulk viscosities. We use the holographic correspondence to evaluate two of the shear viscosities, η⊥≡ηxyxy (perpendicular to the magnetic field) and η∥≡ηxzxz=ηyzyz (parallel to the field). When B ≠0 the shear viscosity perpendicular to the field saturates the viscosity bound η⊥/s=1/(4π), while in the direction parallel to the field the bound is violated since η∥/s<1/(4π). However, the violation of the bound in the case of strongly coupled SYM is minimal even for the largest value of B that can be reached in heavy ion collisions.

  3. Strong-pinning regimes by spherical inclusions in anisotropic type-II superconductors

    Science.gov (United States)

    Willa, R.; Koshelev, A. E.; Sadovskyy, I. A.; Glatz, A.

    2018-01-01

    The current-carrying capacity of type-II superconductors is decisively determined by how well material defect structures can immobilize vortex lines. In order to gain deeper insights into the fundamental pinning mechanisms, we have explored the case of vortex trapping by randomly distributed spherical inclusions using large-scale simulations of the time-dependent Ginzburg–Landau equations. We find that for a small density of particles having diameters of two coherence lengths, the vortex lattice preserves its structure and the critical current j c decays with the magnetic field following a power-law {B}-α with α ≈ 0.66, which is consistent with predictions of strong-pinning theory. For a higher density of particles and/or larger inclusions, the lattice becomes progressively more disordered and the exponent smoothly decreases down to α ≈ 0.3. At high magnetic fields, all inclusions capture a vortex and the critical current decays faster than {B}-1 as would be expected by theory. In the case of larger inclusions with a diameter of four coherence lengths, the magnetic-field dependence of the critical current is strongly affected by the ability of inclusions to capture multiple vortex lines. We found that at small densities, the fraction of inclusions trapping two vortex lines rapidly grows within narrow field range leading to a peak in j c(B)-dependence within this range. With increasing inclusion density, this peak transforms into a plateau, which then smooths out. Using the insights gained from simulations, we determine the limits of applicability of strong-pinning theory and provide different routes to describe vortex pinning beyond those bounds.

  4. Strong-pinning regimes by spherical inclusions in anisotropic type-II superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Willa, R.; Koshelev, A. E.; Sadovskyy, I. A.; Glatz, A.

    2017-11-27

    The current-carrying capacity of type-II superconductors is decisively determined by how well material defect structures can immobilize vortex lines. In order to gain deeper insights into intrinsic pinning mechanisms, we have explored the case of vortex trapping by randomly distributed spherical inclusions using large-scale simulations of the time-dependent Ginzburg-Landau equations. We find that for a small density of particles having diameters of two coherence lengths, the vortex lattice preserves its structure and the critical current jc decays with the magnetic field following a power-law B-a with a ~ 0:66, which is consistent with predictions of strong pinning theory. For higher density of particles and/or larger inclusions, the lattice becomes progressively more disordered and the exponent smoothly decreases down to a ~ 0:3. At high magnetic fields, all inclusions capture a vortex and the critical current decays faster than B-1 as would be expected by theory. In the case of larger inclusions with diameter of four coherence length, the magnetic-field dependence of the critical current is strongly affected by the ability of inclusions to capture multiple vortex lines. We found that at small densities, the fraction of inclusions trapping two vortex lines rapidly grows within narrow field range leading to a shallow peak in jc(B)-dependence within this range. With increasing inclusion density, this peak transforms into a plateau, which then smooths out. Using the insights gained from simulations, we determine the limits of applicability of strong pinning theory and provide different routes to describe vortex pinning beyond those bounds.

  5. Pluripotency transcription factor Sox2 is strongly adsorbed by heparin but requires a protein transduction domain for cell internalization

    Energy Technology Data Exchange (ETDEWEB)

    Albayrak, Cem [Department of Chemical Engineering, Stanford University, 381 North-South Mall, Stanford, CA 94305 (United States); Yang, William C. [Department of Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305 (United States); Swartz, James R., E-mail: jswartz@stanford.edu [Department of Chemical Engineering, Stanford University, 381 North-South Mall, Stanford, CA 94305 (United States); Department of Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305 (United States)

    2013-02-15

    Highlights: ► Both R9Sox2 and Sox2 bind heparin with comparable affinity. ► Both R9Sox2 and Sox2 bind to fibroblasts, but only R9Sox2 is internalized. ► Internalization efficiency of R9Sox2 is 0.3% of the administered protein. ► Heparan sulfate adsorption may be part of a mechanism for managing cell death. -- Abstract: The binding of protein transduction domain (PTD)-conjugated proteins to heparan sulfate is an important step in cellular internalization of macromolecules. Here, we studied the pluripotency transcription factor Sox2, with or without the nonaarginine (R9) PTD. Unexpectedly, we observed that Sox2 is strongly adsorbed by heparin and by the fibroblasts without the R9 PTD. However, only the R9Sox2 fusion protein is internalized by the cells. These results collectively show that binding to heparan sulfate is not sufficient for cellular uptake, thereby supporting a recent hypothesis that other proteins play a role in cell internalization of PTD-conjugated proteins.

  6. Strong anisotropic anomalous Hall effect and spin Hall effect in the chiral antiferromagnetic compounds Mn3X (X =Ge , Sn, Ga, Ir, Rh, and Pt)

    Science.gov (United States)

    Zhang, Yang; Sun, Yan; Yang, Hao; Železný, Jakub; Parkin, Stuart P. P.; Felser, Claudia; Yan, Binghai

    2017-02-01

    We have carried out a comprehensive study of the intrinsic anomalous Hall effect and spin Hall effect of several chiral antiferromagnetic compounds Mn3X (X = Ge, Sn, Ga, Ir, Rh and Pt) by ab initio band structure and Berry phase calculations. These studies reveal large and anisotropic values of both the intrinsic anomalous Hall effect and spin Hall effect. The Mn3X materials exhibit a noncollinear antiferromagnetic order which, to avoid geometrical frustration, forms planes of Mn moments that are arranged in a Kagome-type lattice. With respect to these Kagome planes, we find that both the anomalous Hall conductivity (AHC) and the spin Hall conductivity (SHC) are quite anisotropic for any of these materials. Based on our calculations, we propose how to maximize AHC and SHC for different materials. The band structures and corresponding electron filling, that we show are essential to determine the AHC and SHC, are compared for these different compounds. We point out that Mn3Ga shows a large SHC of about 600 (ℏ /e ) (Ωcm) -1 . Our work provides insights into the realization of strong anomalous Hall effects and spin Hall effects in chiral antiferromagnetic materials.

  7. Experimental and Numerical Evaluation of the Mechanical Behavior of Strongly Anisotropic Light-Weight Metallic Fiber Structures under Static and Dynamic Compressive Loading

    Directory of Open Access Journals (Sweden)

    Olaf Andersen

    2016-05-01

    Full Text Available Rigid metallic fiber structures made from a variety of different metals and alloys have been investigated mainly with regard to their functional properties such as heat transfer, pressure drop, or filtration characteristics. With the recent advent of aluminum and magnesium-based fiber structures, the application of such structures in light-weight crash absorbers has become conceivable. The present paper therefore elucidates the mechanical behavior of rigid sintered fiber structures under quasi-static and dynamic loading. Special attention is paid to the strongly anisotropic properties observed for different directions of loading in relation to the main fiber orientation. Basically, the structures show an orthotropic behavior; however, a finite thickness of the fiber slabs results in moderate deviations from a purely orthotropic behavior. The morphology of the tested specimens is examined by computed tomography, and experimental results for different directions of loading as well as different relative densities are presented. Numerical calculations were carried out using real structural data derived from the computed tomography data. Depending on the direction of loading, the fiber structures show a distinctively different deformation behavior both experimentally and numerically. Based on these results, the prevalent modes of deformation are discussed and a first comparison with an established polymer foam and an assessment of the applicability of aluminum fiber structures in crash protection devices is attempted.

  8. More light on the 2ν{sub 5} Raman overtone of SF{sub 6}: Can a weak anisotropic spectrum be due to a strong transition anisotropy?

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, D.; Rachet, F.; Chrysos, M., E-mail: michel.chrysos@univ-angers.fr [LUNAM Université, Université d’Angers, CNRS UMR 6200, Laboratoire MOLTECH-Anjou, 2 Bd Lavoisier, 49045 Angers (France)

    2014-01-21

    Long known as a fully polarized band with a near vanishing depolarization ratio [η{sub s} = 0.05, W. Holzer and R. Ouillon, Chem. Phys. Lett. 24, 589 (1974)], the 2ν{sub 5} Raman overtone of SF{sub 6} has so far been considered as of having a prohibitively weak anisotropic spectrum [D. P. Shelton and L. Ulivi, J. Chem. Phys. 89, 149 (1988)]. Here, we report the first anisotropic spectrum of this overtone, at room temperature and for 13 gas densities ranging between 2 and 27 amagat. This spectrum is 10 times broader and 50 times weaker than the isotropic counterpart of the overtone [D. Kremer, F. Rachet, and M. Chrysos, J. Chem. Phys. 138, 174308 (2013)] and its profile much more sensitive to pressure effects than the profile of the isotropic spectrum. From our measurements an accurate value for the anisotropy matrix-element |〈000020|Δα|000000〉| was derived and this value was found to be comparable to that of the mean-polarizability ((000020), α{sup ¯} (000000)). Among other conclusions our study offers compelling evidence that, in Raman spectroscopy, highly polarized bands or tiny depolarization ratios are not necessarily incompatible with large polarizability anisotropy transition matrix-elements. Our findings and the way to analyze them suggest that new strategies should be developed on the basis of the complementarity inherent in independent incoherent Raman experiments that run with two different incident-beam polarizations, and on concerted efforts to ab initio calculate accurate data for first and second polarizability derivatives. Values for these derivatives are still rarities in the literature of SF{sub 6}.

  9. Material Induced Anisotropic Damage

    NARCIS (Netherlands)

    Niazi, Muhammad Sohail; Wisselink, H.H.; Meinders, Vincent T.; van den Boogaard, Antonius H.; Hora, P.

    2012-01-01

    The anisotropy in damage can be driven by two different phenomena; anisotropic defor-mation state named Load Induced Anisotropic Damage (LIAD) and anisotropic (shape and/or distribution) second phase particles named Material Induced Anisotropic Damage (MIAD). Most anisotropic damage models are based

  10. Anisotropic universe with anisotropic sources

    Science.gov (United States)

    Aluri, Pavan K.; Panda, Sukanta; Sharma, Manabendra; Thakur, Snigdha

    2013-12-01

    We analyze the state space of a Bianchi-I universe with anisotropic sources. Here we consider an extended state space which includes null geodesics in this background. The evolution equations for all the state observables are derived. Dynamical systems approach is used to study the evolution of these equations. The asymptotic stable fixed points for all the evolution equations are found. We also check our analytic results with numerical analysis of these dynamical equations. The evolution of the state observables are studied both in cosmic time and using a dimensionless time variable. Then we repeat the same analysis with a more realistic scenario, adding the isotropic (dust like dark) matter and a cosmological constant (dark energy) to our anisotropic sources, to study their co-evolution. The universe now approaches a de Sitter space asymptotically dominated by the cosmological constant. The cosmic microwave background anisotropy maps due to shear are also generated in this scenario, assuming that the universe contains anisotropic matter along with the usual (dark) matter and vacuum (dark) energy since decoupling. We find that they contribute dominantly to the CMB quadrupole. We also constrain the current level of anisotropy and also search for any cosmic preferred axis present in the data. We use the Union 2 Supernovae data to this extent. An anisotropy axis close to the mirror symmetry axis seen in the cosmic microwave background data from Planck probe is found.

  11. Anisotropic hydrodynamics: Motivation and methodology

    Energy Technology Data Exchange (ETDEWEB)

    Strickland, Michael

    2014-06-15

    In this proceedings contribution I review recent progress in our understanding of the bulk dynamics of relativistic systems that possess potentially large local rest frame momentum-space anisotropies. In order to deal with these momentum-space anisotropies, a reorganization of relativistic viscous hydrodynamics can be made around an anisotropic background, and the resulting dynamical framework has been dubbed “anisotropic hydrodynamics”. I also discuss expectations for the degree of momentum-space anisotropy of the quark–gluon plasma generated in relativistic heavy ion collisions at RHIC and LHC from second-order viscous hydrodynamics, strong-coupling approaches, and weak-coupling approaches.

  12. Pellet feed adsorbed with the recombinant Lactococcus lactis BFE920 expressing SiMA antigen induced strong recall vaccine effects against Streptococcus iniae infection in olive flounder (Paralichthys olivaceus).

    Science.gov (United States)

    Kim, Daniel; Beck, Bo Ram; Lee, Sun Min; Jeon, Jongsu; Lee, Dong Wook; Lee, Jae Il; Song, Seong Kyu

    2016-08-01

    The aim of this study was to develop a fish feed vaccine that provides effective disease prevention and convenient application. A lactic acid bacterium (LAB), Lactococcus lactis BFE920, was modified to express the SiMA antigen, a membrane protein of Streptococcus iniae. The antigen was engineered to be expressed under the nisin promoter, which is induced by nisin produced naturally by the host LAB. Various sizes (40 ± 3.5 g, 80 ± 2.1 g, and 221 ± 2.4 g) of olive flounder (Paralichthys olivaceus) were vaccinated by feeding the extruded pellet feed, onto which the SiMA-expressing L. lactis BFE920 (1.0 × 10(7) CFU/g) was adsorbed. Vaccine-treated feed was administered twice a day for 1 week, and priming and boosting were performed with a 1-week interval in between. The vaccinated fish had significantly elevated levels of antigen-specific serum antibodies and T cell marker mRNAs: CD4-1, CD4-2, and CD8a. In addition, the feed vaccine significantly induced T cell effector functions, such as the production of IFN-γ and activation of the transcription factor that induces its expression, T-bet. When the flounder were challenged by intraperitoneal infection and bath immersion with S. iniae, the vaccinated fish showed 84% and 82% relative percent survival (RPS), respectively. Furthermore, similar protective effects were confirmed even 3 months after vaccination in a field study (n = 4800), indicating that this feed vaccine elicited prolonged duration of immunopotency. In addition, the vaccinated flounder gained 21% more weight and required 16% less feed to gain a unit of body weight compared to the control group. The data clearly demonstrate that the L. lactis BFE920-SiMA feed vaccine has strong protective effects, induces prolonged vaccine efficacy, and has probiotic effects. In addition, this LAB-based fish feed vaccine can be easily used to target many different pathogens of diverse fish species. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Highly Anisotropic Conductors.

    Science.gov (United States)

    Wan, Jiayu; Song, Jianwei; Yang, Zhi; Kirsch, Dylan; Jia, Chao; Xu, Rui; Dai, Jiaqi; Zhu, Mingwei; Xu, Lisha; Chen, Chaoji; Wang, Yanbin; Wang, Yilin; Hitz, Emily; Lacey, Steven D; Li, Yongfeng; Yang, Bao; Hu, Liangbing

    2017-11-01

    Composite materials with ordered microstructures often lead to enhanced functionalities that a single material can hardly achieve. Many biomaterials with unusual microstructures can be found in nature; among them, many possess anisotropic and even directional physical and chemical properties. With inspiration from nature, artificial composite materials can be rationally designed to achieve this anisotropic behavior with desired properties. Here, a metallic wood with metal continuously filling the wood vessels is developed, which demonstrates excellent anisotropic electrical, thermal, and mechanical properties. The well-aligned metal rods are confined and separated by the wood vessels, which deliver directional electron transport parallel to the alignment direction. Thus, the novel metallic wood composite boasts an extraordinary anisotropic electrical conductivity (σ || /σ ⊥ ) in the order of 10 11 , and anisotropic thermal conductivity (κ || /κ ⊥ ) of 18. These values exceed the highest reported values in existing anisotropic composite materials. The anisotropic functionality of the metallic wood enables it to be used for thermal management applications, such as thermal insulation and thermal dissipation. The highly anisotropic metallic wood serves as an example for further anisotropic materials design; other composite materials with different biotemplates/hosts and fillers can achieve even higher anisotropic ratios, allowing them to be implemented in a variety of applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. An anisotropic elastoplasticity model implemented in FLAG

    Energy Technology Data Exchange (ETDEWEB)

    Buechler, Miles Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Canfield, Thomas R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-12

    Many metals, including Tantalum and Zirconium, exhibit anisotropic elastoplastic behavior at the single crystal level, and if components are manufactured from these metals through forming processes the polycrystal (component) may also exhibit anisotropic elastoplastic behavior. This is because the forming can induce a preferential orientation of the crystals in the polycrystal. One example is a rolled plate of Uranium where the sti /strong orientation of the crystal (c-axis) tends to align itself perpendicular to the rolling direction. If loads are applied to this plate in di erent orientations the sti ness as well as the ow strength of the material will be greater in the through thickness direction than in other directions. To better accommodate simulations of such materials, an anisotropic elastoplasticity model has been implemented in FLAG. The model includes an anisotropic elastic stress model as well as an anisotropic plasticity model. The model could represent single crystals of any symmetry, though it should not be confused with a high- delity crystal plasticity model with multiple slip planes and evolutions. The model is most appropriate for homogenized polycrystalline materials. Elastic rotation of the material due to deformation is captured, so the anisotropic models are appropriate for arbitrary large rotations, but currently they do not account for signi cant change in material texture beyond the elastic rotation of the entire polycrystal.

  15. Anisotropic light diffusion: an oxymoron?

    Science.gov (United States)

    Kienle, Alwin

    2007-05-25

    Light propagation in anisotropic random media is studied in the steady-state and time domains. Solutions of the anisotropic diffusion equation are compared to results obtained by the Monte Carlo method. Contrary to what has been reported so far, we find that even in the "diffusive regime" the anisotropic diffusion equation does not describe correctly the light propagation in anisotropic random media.

  16. Disordered adsorbate phases

    Science.gov (United States)

    Rys, Franz S.

    1985-04-01

    The occurrence of disordered phases at low temperatures in adsorbed monolayers, as shown recently in a domain wall model, is discussed, the main results are summarized and some relevant experimental systems are mentionned.

  17. Molecular Adsorber Coating

    Science.gov (United States)

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  18. Anisotropic ray trace

    Science.gov (United States)

    Lam, Wai Sze Tiffany

    Optical components made of anisotropic materials, such as crystal polarizers and crystal waveplates, are widely used in many complex optical system, such as display systems, microlithography, biomedical imaging and many other optical systems, and induce more complex aberrations than optical components made of isotropic materials. The goal of this dissertation is to accurately simulate the performance of optical systems with anisotropic materials using polarization ray trace. This work extends the polarization ray tracing calculus to incorporate ray tracing through anisotropic materials, including uniaxial, biaxial and optically active materials. The 3D polarization ray tracing calculus is an invaluable tool for analyzing polarization properties of an optical system. The 3x3 polarization ray tracing P matrix developed for anisotropic ray trace assists tracking the 3D polarization transformations along a ray path with series of surfaces in an optical system. To better represent the anisotropic light-matter interactions, the definition of the P matrix is generalized to incorporate not only the polarization change at a refraction/reflection interface, but also the induced optical phase accumulation as light propagates through the anisotropic medium. This enables realistic modeling of crystalline polarization elements, such as crystal waveplates and crystal polarizers. The wavefront and polarization aberrations of these anisotropic components are more complex than those of isotropic optical components and can be evaluated from the resultant P matrix for each eigen-wavefront as well as for the overall image. One incident ray refracting or reflecting into an anisotropic medium produces two eigenpolarizations or eigenmodes propagating in different directions. The associated ray parameters of these modes necessary for the anisotropic ray trace are described in Chapter 2. The algorithms to calculate the P matrix from these ray parameters are described in Chapter 3 for

  19. Anisotropic contrast optical microscope.

    Science.gov (United States)

    Peev, D; Hofmann, T; Kananizadeh, N; Beeram, S; Rodriguez, E; Wimer, S; Rodenhausen, K B; Herzinger, C M; Kasputis, T; Pfaunmiller, E; Nguyen, A; Korlacki, R; Pannier, A; Li, Y; Schubert, E; Hage, D; Schubert, M

    2016-11-01

    An optical microscope is described that reveals contrast in the Mueller matrix images of a thin, transparent, or semi-transparent specimen located within an anisotropic object plane (anisotropic filter). The specimen changes the anisotropy of the filter and thereby produces contrast within the Mueller matrix images. Here we use an anisotropic filter composed of a semi-transparent, nanostructured thin film with sub-wavelength thickness placed within the object plane. The sample is illuminated as in common optical microscopy but the light is modulated in its polarization using combinations of linear polarizers and phase plate (compensator) to control and analyze the state of polarization. Direct generalized ellipsometry data analysis approaches permit extraction of fundamental Mueller matrix object plane images dispensing with the need of Fourier expansion methods. Generalized ellipsometry model approaches are used for quantitative image analyses. These images are obtained from sets of multiple images obtained under various polarizer, analyzer, and compensator settings. Up to 16 independent Mueller matrix images can be obtained, while our current setup is limited to 11 images normalized by the unpolarized intensity. We demonstrate the anisotropic contrast optical microscope by measuring lithographically defined micro-patterned anisotropic filters, and we quantify the adsorption of an organic self-assembled monolayer film onto the anisotropic filter. Comparison with an isotropic glass slide demonstrates the image enhancement obtained by our method over microscopy without the use of an anisotropic filter. In our current instrument, we estimate the limit of detection for organic volumetric mass within the object plane of ≈49 fg within ≈7 × 7 μm 2 object surface area. Compared to a quartz crystal microbalance with dissipation instrumentation, where contemporary limits require a total load of ≈500 pg for detection, the instrumentation demonstrated here improves

  20. Anisotropic Weyl invariance

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Nadal, Guillem [Universidad de Buenos Aires, Buenos Aires (Argentina)

    2017-07-15

    We consider a non-relativistic free scalar field theory with a type of anisotropic scale invariance in which the number of coordinates ''scaling like time'' is generically greater than one. We propose the Cartesian product of two curved spaces, the metric of each space being parameterized by the other space, as a notion of curved background to which the theory can be extended. We study this type of geometries, and find a family of extensions of the theory to curved backgrounds in which the anisotropic scale invariance is promoted to a local, Weyl-type symmetry. (orig.)

  1. Understanding Trends in Catalytic Activity: The Effect of Adsorbate-Adsorbate Interactions for CO Oxidation Over Transition Metals

    DEFF Research Database (Denmark)

    Grabow, Lars; Larsen, Britt Hvolbæk; Nørskov, Jens Kehlet

    2010-01-01

    Using high temperature CO oxidation as the example, trends in the reactivity of transition metals are discussed on the basis of density functional theory (DFT) calculations. Volcano type relations between the catalytic rate and adsorption energies of important intermediates are introduced...... and the effect of adsorbate-adsorbate interaction on the trends is discussed. We find that adsorbate-adsorbate interactions significantly increase the activity of strong binding metals (left side of the volcano) but the interactions do not change the relative activity of different metals and have a very small...... influence on the position of the top of the volcano, that is, on which metal is the best catalyst....

  2. Anisotropic Lyra cosmology

    Indian Academy of Sciences (India)

    Anisotropic Bianchi Type-I cosmological models have been studied on the basis of Lyra's geometry. Two types of models, one with constant deceleration parameter and the other with variable deceleration parameter have been derived by considering a time-dependent displacement field.

  3. Anisotropic Concrete Compressive Strength

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2017-01-01

    When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...

  4. Evaluation of adsorbents for the Ta-178 generator

    International Nuclear Information System (INIS)

    Neirinckx, R.D.; Johnson, P.C.; Leblanc, A.; Trumper, J.

    1984-01-01

    The currently used Ta-178 generator is based on a radiation sensitive adsorbent and can be eluted about 50 times before W-178 breakthrough becomes unacceptable. The authors evaluated a series of inorganic and organic adsorbents as support for this generator. Hydrated inorganic materials adsorb tantalum very strongly from most aqueous solutions and none was found useful for the W-178/Ta-178 generator. Tantalum complexing agents are not able to desorb tantalum without dissolving the adsorbents to an appreciable extent. Chelating resins with a high affinity for W were investigated because they could reduce the W-178 breakthrough. They also adsorb tantalum too strongly to be suitable as substrates for the Ta-178 generator. The Bio-Rad AG1x8 system was found to be superior to the other tested systems. The effects of autoclaving, complexant additives and prolonged elution on the Ta-178 yield were measured and the chemical breakdown products quantitated

  5. Stability of anisotropic stellar filaments

    Science.gov (United States)

    Bhatti, M. Zaeem-ul-Haq; Yousaf, Z.

    2017-12-01

    The study of perturbation of self-gravitating celestial cylindrical object have been carried out in this paper. We have designed a framework to construct the collapse equation by formulating the modified field equations with the background of f(R , T) theory as well as dynamical equations from the contracted form of Bianchi identities with anisotropic matter configuration. We have encapsulated the radial perturbations on metric and material variables of the geometry with some known static profile at Newtonian and post-Newtonian regimes. We examined a strong dependence of unstable regions on stiffness parameter which measures the rigidity of the fluid. Also, the static profile and matter variables with f(R , T) dark source terms control the instability of compact cylindrical system.

  6. Wireless energy transfer between anisotropic metamaterials shells

    Energy Technology Data Exchange (ETDEWEB)

    Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José, E-mail: jsdehesa@upv.es

    2014-06-15

    The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated. -- Highlights: •Anisotropic metamaterial shells exhibit high quality factors and sub-wavelength size. •Exchange of electromagnetic energy between shells with high efficiency is analyzed. •Strong coupling is supported with high wireless transfer efficiency. •End-to-end energy transfer efficiencies higher than 83% can be predicted.

  7. Comparison of hot Soxhlet and accelerated solvent extractions with microwave and supercritical fluid extractions for the determination of polycyclic aromatic hydrocarbons and nitrated derivatives strongly adsorbed on soot collected inside a diesel particulate filter.

    Science.gov (United States)

    Oukebdane, K; Portet-Koltalo, F; Machour, N; Dionnet, F; Desbène, P L

    2010-06-30

    Several methods of extraction were optimized to extract polycyclic aromatic hydrocarbons (PAHs), their nitrated derivatives and heavy n-alkanes from a highly adsorptive particulate matter resulting from the combustion of diesel fuel in a diesel engine. This particular carbonaceous particulate matter, collected at high temperatures in cordierite diesel particulate filters (DPF), which are optimized for removing diesel particles from diesel engine exhaust emissions, appeared extremely refractory to extractions using the classical extracting conditions for these pollutants. In particular, the method of accelerated solvent extraction (ASE) is described in detail here. Optimization was performed through experimental design to understand the impact of each factor studied and the factors' possible interactions on the recovery yields. The conventional extraction technique, i.e., Soxhlet extraction, was also carried out, but the lack of quantitative extractions led us to use a more effective approach: hot Soxhlet. It appeared that the extraction of the heaviest PAHs and nitroPAHs by either the optimized ASE or hot Soxhlet processes was far from complete. To enhance recovery yields, we tested original solvent mixtures of aromatic and heteroaromatic solvents. Thereafter, these two extraction techniques were compared to microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE). In every case, the only solvent mixture that permitted quantitative extraction of the heaviest PAHs from the diesel soot was composed of pyridine and diethylamine, which has a strong electron-donor character. Conversely, the extraction of the nitrated PAHs was significantly improved by the use of an electron-acceptor solvent or by introducing a small amount of acetic acid into the pyridine. It was demonstrated that, for many desirable features, no single extraction technique stound out as the best: ASE, MAE or SFE could all challenge hot Soxhlet for favourable extractions

  8. Anisotropic magnetocapacitance in ferromagnetic-plate capacitors

    Science.gov (United States)

    Haigh, J. A.; Ciccarelli, C.; Betz, A. C.; Irvine, A.; Novák, V.; Jungwirth, T.; Wunderlich, J.

    2015-04-01

    The capacitance of a parallel-plate capacitor can depend on the applied magnetic field. Previous studies have identified capacitance changes induced via classical Lorentz force or spin-dependent Zeeman effects. Here we measure a magnetization direction-dependent capacitance in parallel-plate capacitors where one plate is a ferromagnetic semiconductor, gallium manganese arsenide. This anisotropic magnetocapacitance is due to the anisotropy in the density of states dependent on the magnetization through the strong spin-orbit interaction.

  9. Metal adsorbent for alkaline etching aqua solutions of Si wafer

    International Nuclear Information System (INIS)

    Tamada, Masao; Ueki, Yuji; Seko, Noriaki; Takeda, Toshihide; Kawano, Shin-ichi

    2012-01-01

    High performance adsorbent is expected to be synthesized for the removal of Ni and Cu ions from strong alkaline solution used in the surface etching process of Si wafer. Fibrous adsorbent was synthesized by radiation-induce emulsion graft polymerization onto polyethylene nonwoven fabric and subsequent amination. The reaction condition was optimized using 30 L reaction vessel and nonwoven fabric, 0.3 m width and 18 m long. The resulting fibrous adsorbent was evaluated by 48 wt% NaOH and KOH contaminated with Ni and Cu ions, respectively. The concentration levels of Ni and Cu ions was reduced to less than 1 μg/kg (ppb) at the flow rate of 10 h −1 in space velocity. The life of adsorbent was 30 times higher than that of the commercialized resin. This novel adsorbent was commercialized as METOLATE ® since the ability of adsorption is remarkably higher than that of commercial resin used practically in Si wafer processing. - Highlights: ► Adsorbent was synthesized by radiation-induced emulsion graft polymerization. ► Degree of grafting reached 120% at the pre-irradiation of 50 kGy. ► The resulting adsorbent removed Ni and Cu ion in strong alkaline solution. ► Adsorbent was commercialized for filter of Si wafer etchant.

  10. Anisotropic elliptic optical fibers

    Science.gov (United States)

    Kang, Soon Ahm

    1991-05-01

    The exact characteristic equation for an anisotropic elliptic optical fiber is obtained for odd and even hybrid modes in terms of infinite determinants utilizing Mathieu and modified Mathieu functions. A simplified characteristic equation is obtained by applying the weakly guiding approximation such that the difference in the refractive indices of the core and the cladding is small. The simplified characteristic equation is used to compute the normalized guide wavelength for an elliptical fiber. When the anisotropic parameter is equal to unity, the results are compared with the previous research and they are in close agreement. For a fixed value normalized cross-section area or major axis, the normalized guide wavelength lambda/lambda(sub 0) for an anisotropic elliptic fiber is small for the larger value of anisotropy. This condition indicates that more energy is carried inside of the fiber. However, the geometry and anisotropy of the fiber have a smaller effect when the normalized cross-section area is very small or very large.

  11. An anisotropic tertiary creep damage constitutive model for anisotropic materials

    International Nuclear Information System (INIS)

    Stewart, Calvin M.; Gordon, Ali P.; Ma, Young Wha; Neu, Richard W.

    2011-01-01

    When an anisotropic material is subject to creep conditions and a complex state of stress, an anisotropic creep damage behavior is observed. Previous research has focused on the anisotropic creep damage behavior of isotropic materials but few constitutive models have been developed for anisotropic creeping solids. This paper describes the development of a new anisotropic tertiary creep damage constitutive model for anisotropic materials. An advanced tensorial damage formulation is implemented which includes both material orientation relative to loading and the degree of creep damage anisotropy in the model. A variation of the Norton-power law for secondary creep is implemented which includes the Hill's anisotropic analogy. Experiments are conducted on the directionally-solidified bucket material DS GTD-111. The constitutive model is implemented in a user programmable feature (UPF) in ANSYS FEA software. The ability of the constitutive model to regress to the Kachanov-Rabotnov isotropic tertiary creep damage model is demonstrated through comparison with uniaxial experiments. A parametric study of both material orientation and stress rotation are conducted. Results indicate that creep deformation is modeled accurately; however an improved damage evolution law may be necessary. - Highlights: → The deformation of anisotropic creeping solid is directionally dependent. → Few constitutive models have been developed to deal with anisotropic behavior. → A transversely-isotropic nickel base superalloy, DS GTD-111, is studied. → A vector constitutive model based on the Kachanov-Rabotnov formulation is developed. → The new model accurately models deformation at various orientations.

  12. Anisotropic power-law k-inflation

    Science.gov (United States)

    Ohashi, Junko; Soda, Jiro; Tsujikawa, Shinji

    2013-11-01

    It is known that power-law k-inflation can be realized for the Lagrangian P=Xg(Y), where X=-(∂ϕ)2/2 is the kinetic energy of a scalar field ϕ and g is an arbitrary function in terms of Y=Xeλϕ/Mpl (λ is a constant and Mpl is the reduced Planck mass). In the presence of a vector field coupled to the inflaton with an exponential coupling f(ϕ)∝eμϕ/Mpl, we show that the models with the Lagrangian P=Xg(Y) generally give rise to anisotropic inflationary solutions with Σ/H=constant, where Σ is an anisotropic shear and H is an isotropic expansion rate. Provided these anisotropic solutions exist in the regime where the ratio Σ/H is much smaller than 1, they are stable attractors irrespective of the forms of g(Y). We apply our results to concrete models of k-inflation such as the generalized dilatonic ghost condensate and the Dirac-Born-Infeld model and we numerically show that the solutions with different initial conditions converge to the anisotropic power-law inflationary attractors. Even in the de Sitter limit (λ→0) such solutions can exist, but in this case the null energy condition is generally violated. The latter property is consistent with the Wald’s cosmic conjecture stating that the anisotropic hair does not survive on the de Sitter background in the presence of matter respecting the dominant/strong energy conditions.

  13. Material Induced Anisotropic Damage in DP600

    NARCIS (Netherlands)

    Niazi, Muhammad Sohail; Wisselink, H.H.; Meinders, Vincent T.; van den Boogaard, Antonius H.

    2013-01-01

    Plasticity induced damage development in metals is anisotropic by nature. The anisotropy in damage is driven by two different phenomena; anisotropic deformation state i.e. Load Induced Anisotropic Damage (LIAD) and anisotropic microstructure i.e. Material Induced Anisotropic Damage (MIAD). The

  14. High performance Mo adsorbent PZC

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1998-10-01

    We have developed Mo adsorbents for natural Mo(n, {gamma}){sup 99}Mo-{sup 99m}Tc generator. Among them, we called the highest performance adsorbent PZC that could adsorb about 250 mg-Mo/g. In this report, we will show the structure, adsorption mechanism of Mo, and the other useful properties of PZC when you carry out the examination of Mo adsorption and elution of {sup 99m}Tc. (author)

  15. Anisotropic Concrete Compressive Strength

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2017-01-01

    When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...... correlation to the curing time. The experiments show no correlation between the anisotropy and the curing time and a small strength difference between the two drilling directions. The literature shows variations on which drilling direction that is strongest. Based on a Monto Carlo simulation of the expected...

  16. Dynamics of anisotropic particles under waves

    Science.gov (United States)

    Dibenedetto, Michelle; Ouellette, Nicholas; Koseff, Jeffrey

    2017-11-01

    We present results on anisotropic particles in wavy flows in order to gain insight into the transport and mixing of microplastic particles in the near-shore environment. From theory and numerical simulations, we find that the rate of alignment of the particles is not constant and depends strongly on their initial orientation; thus, variations in initial particle orientation result in dispersion of anisotropic-particle plumes. We find that this dispersion is a function of the particle's eccentricity and the ratio of the settling and wave time scales. Experiments in which non-spherical particles of various shapes are released under surface gravity waves were also performed. Our main goal is to explore the effects of particle shape under various wave scenarios. We vary the aspect ratio of the particle in our experiments while holding other variables constant. Our results demonstrate that particle shape can be important when predicting transport.

  17. The shear viscosity in anisotropic phases

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Sachin [Department of Physics, Cornell University,Ithaca, New York 14853 (United States); Samanta, Rickmoy; Trivedi, Sandip P. [Department of Theoretical Physics, Tata Institute of Fundamental Research,Colaba, Mumbai 400005 (India)

    2015-10-06

    We construct anisotropic black brane solutions and analyse the behaviour of some of their metric perturbations. These solutions correspond to field theory duals in which rotational symmetry is broken due an externally applied, spatially constant, force. We find, in several examples, that when the anisotropy is sufficiently big compared to the temperature, some components of the viscosity tensor can become very small in units of the entropy density, parametrically violating the KSS bound. We obtain an expression relating these components of the viscosity, in units of the entropy density, to a ratio of metric components at the horizon of the black brane. This relation is generally valid, as long as the forcing function is translationally invariant, and it directly connects the parametric violation of the bound to the anisotropy in the metric at the horizon. Our results suggest the possibility that such small components of the viscosity tensor might also arise in anisotropic strongly coupled fluids found in nature.

  18. Positronium chemistry in porous adsorbents

    International Nuclear Information System (INIS)

    Foti, G.; Nagy, L.G.; Moravcsik, G.; Schay, G.

    1981-01-01

    Kinetic studies on the annihilation of orthopositronium in porous adsorbents have been performed using lifetime spectroscopy. The positron source applied was 22 Na with 0.2 MBq activity. The adsorbents investigated were silica gels of different particle size and pore structure. The appearance of the long-lived component in the lifetime spectra can be explained by the diffusion of the orthopositronium into the pores affected by the particle size and the pore size of the adsorbent, the coverage on it and the chemical nature of the adsorbate. The long-term aim of the work is to determine and to explain these effects. (author)

  19. Transient anisotropic magnetic field calculation

    International Nuclear Information System (INIS)

    Jesenik, Marko; Gorican, Viktor; Trlep, Mladen; Hamler, Anton; Stumberger, Bojan

    2006-01-01

    For anisotropic magnetic material, nonlinear magnetic characteristics of the material are described with magnetization curves for different magnetization directions. The paper presents transient finite element calculation of the magnetic field in the anisotropic magnetic material based on the measured magnetization curves for different magnetization directions. For the verification of the calculation method some results of the calculation are compared with the measurement

  20. Heat Conductance is Strongly Anisotropic for Pristine Silicon Nanowires

    DEFF Research Database (Denmark)

    Markussen, Troels; Jauho, Antti-Pekka; Brandbyge, Mads

    2008-01-01

    along the 100 and 111 directions. We show that the anisotropies can be qualitatively understood and reproduced from the bulk phonon band structure. Ab initio density functional theory (DFT) is used to study the thinnest wires, but becomes computationally prohibitive for larger diameters, where we...

  1. Anisotropic surface chemistry properties and adsorption behavior of silicate mineral crystals.

    Science.gov (United States)

    Xu, Longhua; Tian, Jia; Wu, Houqin; Fang, Shuai; Lu, Zhongyuan; Ma, Caifeng; Sun, Wei; Hu, Yuehua

    2018-03-07

    Anisotropic surface properties of minerals play an important role in a variety of fields. With a focus on the two most intensively investigated silicate minerals (i.e., phyllosilicate minerals and pegmatite aluminosilicate minerals), this review highlights the research on their anisotropic surface properties based on their crystal structures. Four surface features comprise the anisotropic surface chemistry of minerals: broken bonds, energy, wettability, and charge. Analysis of surface broken bond and energy anisotropy helps to explain the cleavage and growth properties of mineral crystals, and understanding surface wettability and charge anisotropy is critical to the analysis of minerals' solution behavior, such as their flotation performance and rheological properties. In a specific reaction, the anisotropic surface properties of minerals are reflected in the adsorption strengths of reagents on different mineral surfaces. Combined with the knowledge of mineral crushing and grinding, a thorough understanding of the anisotropic surface chemistry properties and the anisotropic adsorption behavior of minerals will lead to the development of effective relational models comprising their crystal structure, surface chemistry properties, and targeted reagent adsorption. Overall, such a comprehensive approach is expected to firmly establish the connection between selective cleavage of mineral crystals for desired surfaces and designing novel reagents selectively adsorbed on the mineral surfaces. As tools to characterize the anisotropic surface chemistry properties of minerals, DLVO theory, atomic force microscopy (AFM), and molecular dynamics (MD) simulations are also reviewed. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Thermodynamics of anisotropic branes

    Energy Technology Data Exchange (ETDEWEB)

    Ávila, Daniel [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, A.P. 70-542, México D.F. 04510 (Mexico); Fernández, Daniel [Max-Planck-Institut für Physik,Föhringer Ring 6, 80805 München (Germany); Patiño, Leonardo [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, A.P. 70-542, México D.F. 04510 (Mexico); Trancanelli, Diego [Institute of Physics, University of São Paulo,05314-970 São Paulo (Brazil)

    2016-11-22

    We study the thermodynamics of flavor D7-branes embedded in an anisotropic black brane solution of type IIB supergravity. The flavor branes undergo a phase transition between a ‘Minkowski embedding’, in which they lie outside of the horizon, and a ‘black hole embedding’, in which they fall into the horizon. This transition depends on the black hole temperature, its degree of anisotropy, and the mass of the flavor degrees of freedom. It happens either at a critical temperature or at a critical anisotropy. A general lesson we learn from this analysis is that the anisotropy, in this particular realization, induces similar effects as the temperature. In particular, increasing the anisotropy bends the branes more and more into the horizon. Moreover, we observe that the transition becomes smoother for higher anisotropies.

  3. Anisotropic Rabi model

    Directory of Open Access Journals (Sweden)

    Qiong-Tao Xie

    2014-06-01

    Full Text Available We define the anisotropic Rabi model as the generalization of the spin-boson Rabi model: The Hamiltonian system breaks the parity symmetry; the rotating and counterrotating interactions are governed by two different coupling constants; a further parameter introduces a phase factor in the counterrotating terms. The exact energy spectrum and eigenstates of the generalized model are worked out. The solution is obtained as an elaboration of a recently proposed method for the isotropic limit of the model. In this way, we provide a long-sought solution of a cascade of models with immediate relevance in different physical fields, including (i quantum optics, a two-level atom in single-mode cross-electric and magnetic fields; (ii solid-state physics, electrons in semiconductors with Rashba and Dresselhaus spin-orbit coupling; and (iii mesoscopic physics, Josephson-junction flux-qubit quantum circuits.

  4. Adsorbed Water Illustration

    Science.gov (United States)

    2008-01-01

    The Thermal and Electrical Conductivity Probe on NASA's Phoenix Mars Lander detected small and variable amounts of water in the Martian soil. In this schematic illustration, water molecules are represented in red and white; soil minerals are represented in green and blue. The water, neither liquid, vapor, nor solid, adheres in very thin films of molecules to the surfaces of soil minerals. The left half illustrates an interpretation of less water being adsorbed onto the soil-particle surface during a period when the tilt, or obliquity, of Mars' rotation axis is small, as it is in the present. The right half illustrates a thicker film of water during a time when the obliquity is greater, as it is during cycles on time scales of hundreds of thousands of years. As the humidity of the atmosphere increases, more water accumulates on mineral surfaces. Thicker films behave increasingly like liquid water. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  5. Application of the anisotropic phase-field crystal model to investigate the lattice systems of different anisotropic parameters and orientations

    Science.gov (United States)

    Kundin, Julia; Ajmal Choudhary, Muhammad

    2017-07-01

    In this article, we present the recent advances in the development of the anisotropic phase-field crystal (APFC) model. These advances are important in basic researches for multiferroic and thermoelectric materials with anisotropic crystal lattices and in thin-film applications. We start by providing a general description of the model derived in our previous studies based on the crystal symmetry and the microscopic dynamical density functional theory for anisotropic interactions and show that there exist only two possible degrees of freedom for the anisotropic lattices which are described by two independent parameters. New findings concerning the applications of the APFC model for the estimation of the elastic modules of anisotropic systems including sheared and stretched lattices as well as for the investigation of the heterogeneous thin film growth are described. The simulation results demonstrate the strong dependency of the misfit dislocation formation during the film growth on the anisotropy and reveal the asymmetric behavior in the cases of positive and negative misfits. We also present the development of the amplitude representation for the full APFC model of two orientation variants and show the relationship between the wave vectors and the base angles of the anisotropic lattices.

  6. Anisotropic Density Estimation in Global Illumination

    DEFF Research Database (Denmark)

    Schjøth, Lars

    2009-01-01

    and bias in estimates. Good results are obtained by the use of anisotropic filtering. Two methods handles the most common cases; filtering illumination reflected from object surfaces. One methods extends filtering to the temporal domain and one performs filtering on illumination from participating media......Density estimation employed in multi-pass global illumination algorithms gives cause to a trade-off problem between bias and noise. The problem is seen most evident as blurring of strong illumination features. This thesis addresses the problem, presenting four methods that reduce both noise...

  7. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  8. Disadvantage factor for anisotropic scattering

    International Nuclear Information System (INIS)

    Saad, E.A.; Abdel Krim, M.S.; EL-Dimerdash, A.A.

    1990-01-01

    The invariant embedding method is used to solve the problem for a two region reactor with anisotropic scattering and to compute the disadvantage factor necessary for calculating some reactor parameters

  9. Photon states in anisotropic media

    Indian Academy of Sciences (India)

    Abstract. Quantum aspects of optical polarization are discussed for waves traveling in anisotropic dielectric media with a view to relate the dynamics of polarization with that of photon spin and its manipulation by classical polarizers.

  10. Black Sprayable Molecular Adsorber Coating

    Data.gov (United States)

    National Aeronautics and Space Administration — The main objective of this technology project is to develop, optimize, and flight qualify a black version of the molecular adsorber coating and a conductive version...

  11. Elution by Le Chatelier's principle for maximum recyclability of adsorbents: applied to polyacrylamidoxime adsorbents for extraction of uranium from seawater.

    Science.gov (United States)

    Oyola, Yatsandra; Vukovic, Sinisa; Dai, Sheng

    2016-05-28

    Amidoxime-based polymer adsorbents have attracted interest within the last decade due to their high adsorption capacities for uranium and other rare earth metals from seawater. The ocean contains an approximated 4-5 billion tons of uranium and even though amidoxime-based adsorbents have demonstrated the highest uranium adsorption capacities to date, they are still economically impractical because of their limited recyclability. Typically, the adsorbed metals are eluted with a dilute acid solution that not only damages the amidoxime groups (metal adsorption sites), but is also not strong enough to remove the strongly bound vanadium, which decreases the adsorption capacity with each cycle. We resolved this challenge by incorporating Le Chatelier's principle to recycle adsorbents indefinitely. We used a solution with a high concentration of amidoxime-like chelating agents, such as hydroxylamine, to desorb nearly a 100% of adsorbed metals, including vanadium, without damaging the metal adsorption sites and preserving the high adsorption capacity. The method takes advantage of knowing the binding mode between the amidoxime ligand and the metal and mimics it with chelating agents that then in a Le Chatelier's manner removes metals by shifting to a new chemical equilibrium. For this reason the method is applicable to any ligand-metal adsorbent and it will make an impact on other extraction technologies.

  12. Propagation of waves in a gravitating and rotating anisotropic heat ...

    African Journals Online (AJOL)

    An inviscid, unbounded, collisionless, gravitating, rotating and heat conducting anisotropic plasma medium which is drifting is considered. The medium is assumed to be embedded in a strong magnetic field. A general dispersion relation is derived using normal mode analysis and its various limiting cases are discussed, ...

  13. Anisotropic nonequilibrium hydrodynamic attractor

    Science.gov (United States)

    Strickland, Michael; Noronha, Jorge; Denicol, Gabriel S.

    2018-02-01

    We determine the dynamical attractors associated with anisotropic hydrodynamics (aHydro) and the DNMR equations for a 0 +1 d conformal system using kinetic theory in the relaxation time approximation. We compare our results to the nonequilibrium attractor obtained from the exact solution of the 0 +1 d conformal Boltzmann equation, the Navier-Stokes theory, and the second-order Mueller-Israel-Stewart theory. We demonstrate that the aHydro attractor equation resums an infinite number of terms in the inverse Reynolds number. The resulting resummed aHydro attractor possesses a positive longitudinal-to-transverse pressure ratio and is virtually indistinguishable from the exact attractor. This suggests that an optimized hydrodynamic treatment of kinetic theory involves a resummation not only in gradients (Knudsen number) but also in the inverse Reynolds number. We also demonstrate that the DNMR result provides a better approximation of the exact kinetic theory attractor than the Mueller-Israel-Stewart theory. Finally, we introduce a new method for obtaining approximate aHydro equations which relies solely on an expansion in the inverse Reynolds number. We then carry this expansion out to the third order, and compare these third-order results to the exact kinetic theory solution.

  14. Self-force on dislocation segments in anisotropic crystals

    International Nuclear Information System (INIS)

    Fitzgerald, S P; Aubry, S

    2010-01-01

    A dislocation segment in a crystal experiences a 'self-force', by virtue of the orientation dependence of its elastic energy. If the crystal is elastically isotropic, this force is manifested as a couple acting to rotate the segment toward the lower energy of the pure screw orientation (i.e. acting to align the dislocation line with its Burgers vector). If the crystal is anisotropic, there are additional contributions to the couple, arising from the more complex energy landscape of the lattice itself. These effects can strongly influence the dynamic evolution of dislocation networks, and via their governing role in dislocation multiplication phenomena, control plastic flow in metals. In this paper we develop a model for dislocation self-forces in a general anisotropic crystal, and briefly consider the technologically important example of α-iron, which becomes increasingly anisotropic as the temperature approaches that of the α-γ phase transition at 912 0 C.

  15. Formulation of cross-anisotropic failure criterion for soils

    Directory of Open Access Journals (Sweden)

    Yi-fei Sun

    2013-10-01

    Full Text Available Inherently anisotropic soil fabric has a considerable influence on soil strength. To model this kind of inherent anisotropy, a three-dimensional anisotropic failure criterion was proposed, employing a scalar-valued anisotropic variable and a modified general threedimensional isotropic failure criterion. The scalar-valued anisotropic variable in all sectors of the deviatoric plane was defined by correlating a normalized stress tensor with a normalized fabric tensor. Detailed comparison between the available experimental data and the corresponding model predictions in the deviatoric plane was conducted. The proposed failure criterion was shown to well predict the failure behavior in all sectors, especially in sector II with the Lode angle ranging between 60° and 120°, where the prediction was almost in accordance with test data. However, it was also observed that the proposed criterion overestimated the strength of dense Santa Monica Beach sand in sector III where the intermediate principal stress ratio b varied from approximately 0.2 to 0.8, and slightly underestimated the strength when b was between approximately 0.8 and 1. The difference between the model predictions and experimental data was due to the occurrence of shear bending, which might reduce the measured strength. Therefore, the proposed anisotropic failure criterion has a strong ability to characterize the failure behavior of various soils and potentially allows a better description of the influence of the loading direction with respect to the soil fabric.

  16. Membrane adsorber for endotoxin removal

    Directory of Open Access Journals (Sweden)

    Karina Moita de Almeida

    Full Text Available ABSTRACT The surface of flat-sheet nylon membranes was modified using bisoxirane as the spacer and polyvinyl alcohol as the coating polymer. The amino acid histidine was explored as a ligand for endotoxins, aiming at its application for endotoxin removal from aqueous solutions. Characterization of the membrane adsorber, analysis of the depyrogenation procedures and the evaluation of endotoxin removal efficiency in static mode are discussed. Ligand density of the membranes was around 7 mg/g dry membrane, allowing removal of up to 65% of the endotoxins. The performance of the membrane adsorber prepared using nylon coated with polyvinyl alcohol and containing histidine as the ligand proved superior to other membrane adsorbers reported in the literature. The lack of endotoxin adsorption on nylon membranes without histidine confirmed that endotoxin removal was due to the presence of the ligand at the membrane surface. Modified membranes were highly stable, exhibiting a lifespan of approximately thirty months.

  17. Kinetics of conformational changes of fibronectin adsorbed onto model surfaces.

    Science.gov (United States)

    Baujard-Lamotte, L; Noinville, S; Goubard, F; Marque, P; Pauthe, E

    2008-05-01

    Fibronectin (FN), a large glycoprotein found in body fluids and in the extracellular matrix, plays a key role in numerous cellular behaviours. We investigate FN adsorption onto hydrophilic bare silica and hydrophobic polystyrene (PS) surfaces using Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) in aqueous medium. Adsorption kinetics using different bulk concentrations of FN were followed for 2h and the surface density of adsorbed FN and its time-dependent conformational changes were determined. When adsorption occurs onto the hydrophilic surface, FN molecules keep their native conformation independent of the adsorption conditions, but the amount of adsorbed FN increases with time and the bulk concentration. Although the protein surface density is the same on the hydrophobic PS surface, this has a strong impact on the average conformation of the adsorbed FN layer. Indeed, interfacial hydration changes induced by adsorption onto the hydrophobic surface lead to a decrease in unhydrated beta-sheet content and cause an increase in hydrated beta-strand and hydrated random domain content of adsorbed FN. This conformational change is mainly dependent on the bulk concentration. Indeed, at low bulk concentrations, the secondary structures of adsorbed FN molecules undergo strong unfolding, allowing an extended and hydrated conformation of the protein. At high bulk concentrations, the molecular packing reduces the unfolding of the stereoregular structures of the FN molecules, preventing stronger spreading of the protein.

  18. Continuum mechanics of anisotropic materials

    CERN Document Server

    Cowin, Stephen C

    2013-01-01

    Continuum Mechanics of Anisotropic Materials(CMAM) presents an entirely new and unique development of material anisotropy in the context of an appropriate selection and organization of continuum mechanics topics. These features will distinguish this continuum mechanics book from other books on this subject. Textbooks on continuum mechanics are widely employed in engineering education, however, none of them deal specifically with anisotropy in materials. For the audience of Biomedical, Chemical and Civil Engineering students, these materials will be dealt with more frequently and greater accuracy in their analysis will be desired. Continuum Mechanics of Anisotropic Materials' author has been a leader in the field of developing new approaches for the understanding of anisotropic materials.

  19. Neutron and light scattering studies of polymers adsorbed on laponite

    International Nuclear Information System (INIS)

    Nelson, Andrew Robert John

    2002-01-01

    The adsorption of poly(ethylene oxide) (PEO) and various poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic) copolymers onto the synthetic clay Laponite, was investigated using Small Angle Neutron Scattering (SANS) and Dynamic Light Scattering (DLS). The Laponite particles are anisotropic, with a relatively high aspect ratio; but are the same order of magnitude in size as the polymer radius of gyration. Consequently, the particles present a radically different adsorption geometry compared to a locally planar interface, that is assumed by the majority of adsorption studies. The PEO homo-polymer formed thin layers, with the layer thickness being much smaller on the face than on the edge of the particle. Furthermore, the face thickness remained constant with increasing molecular weight, unlike the edge thickness, which grew with a small power law dependence on the molecular weight. Although the hydrodynamic thicknesses (DLS) were larger than those observed with SANS, the layer thicknesses were much smaller than that expected for polymer adsorption on spherical particles. Experimentally determined inter-particle structure factors suggested that the adsorbed PEO layers provided a steric repulsion term to the inter-particle interactions. The autocorrelation functions for aggregating Laponite dispersions were followed with DLS. It was found that the stabilisation provided by the adsorbed layer reduced the aggregation rate, with lower molecular weights being most effective. SANS and DLS measurements on Laponite/Pluronic systems revealed that the thickness of the Pluronic layer was the same on the edge and face of the particle. As the Pluronic anchor fraction decreased, and the PEO block molecular weight increased, a growth in the layer size and adsorbed amount was observed. The low anchor fraction Pluronics had higher adsorbed amounts and thicker layers, than the highest M w homo-polymers, demonstrating the importance of the PPO block in the

  20. Anisotropic phenomena in gauge/gravity duality

    International Nuclear Information System (INIS)

    Zeller, Hansjoerg

    2014-01-01

    In this thesis we use gauge/gravity duality to model anisotropic effects realised in nature. Firstly we analyse transport properties in holographic systems with a broken rotational invariance. Secondly we discuss geometries dual to IR fixed points with anisotropic scaling behaviour, which are related to quantum critical points in condensed matter systems. Gauge/gravity duality relates a gravity theory in Anti-de Sitter space to a lower dimensional strongly coupled quantum field theory in Minkowski space. Over the past decade this duality provided many insights into systems at strong coupling, e.g. quark-gluon plasma and condensed matter close to quantum critical points. One very important result computed in this framework is the value of the shear viscosity divided by the entropy density in strongly coupled theories. The quantitative result agrees very well with measurements of the ratio in quark-gluon plasma. However, for isotropic two derivative Einstein gravity it is temperature independent. We show that by breaking the rotational symmetry of a system we obtain a temperature dependent shear viscosity over entropy density. This is important to make contact with real world systems, since substances in nature display such dependence. In addition, we derive various transport properties in strongly coupled anisotropic systems using the gauge/gravity dictionary. The most notable results include an electrical conductivity with Drude behaviour in the low frequency region. This resembles conductors with broken translational invariance. However, we did not implement the breaking explicitly. Furthermore, our analysis shows that this setup models effects, resembling the piezoelectric and exoelectric effects, known from liquid crystals. In a second project we discuss a geometry with non-trivial scaling behaviour in order to model an IR fixed point of condensed matter theories. We construct the UV completion of this geometry and analyse its properties by computing the

  1. Anisotropic Characteristics of Turbulence Dissipation in Swirling Flow: A Direct Numerical Simulation Study

    Directory of Open Access Journals (Sweden)

    Xingtuan Yang

    2015-01-01

    Full Text Available This study investigates the anisotropic characteristics of turbulent energy dissipation rate in a rotating jet flow via direct numerical simulation. The turbulent energy dissipation tensor, including its eigenvalues in the swirling flows with different rotating velocities, is analyzed to investigate the anisotropic characteristics of turbulence and dissipation. In addition, the probability density function of the eigenvalues of turbulence dissipation tensor is presented. The isotropic subrange of PDF always exists in swirling flows relevant to small-scale vortex structure. Thus, with remarkable large-scale vortex breakdown, the isotropic subrange of PDF is reduced in strongly swirling flows, and anisotropic energy dissipation is proven to exist in the core region of the vortex breakdown. More specifically, strong anisotropic turbulence dissipation occurs concentratively in the vortex breakdown region, whereas nearly isotropic turbulence dissipation occurs dispersively in the peripheral region of the strong swirling flows.

  2. NEUTRON REFLECTIVITY STUDY OF END-ADSORBED DIBLOCK COPOLYMERS - CROSS-OVER FROM MUSHROOMS TO BRUSHES

    NARCIS (Netherlands)

    FIELD, JB; TOPRAKCIOGLU, C; DAI, L; HADZIIOANNOU, G; SMITH, G; HAMILTON, W

    1992-01-01

    We report neutron reflectivity data on polystyrene-poly(vinyl-2-pyridine) (PS-PVP) diblock copolymers adsorbed onto quartz from the selective solvent toluene (a good solvent for PS, but a poor one for PVP). The PVP > block adsorbs strongly to form a thin layer on the quartz substrate, while the PS

  3. Magnetic relaxation in anisotropic magnets

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1971-01-01

    The line shape and the kinematic and thermodynamic slowing down of the critical and paramagnetic relaxation in axially anisotropic materials are discussed. Kinematic slowing down occurs only in the longitudinal relaxation function. The thermodynamic slowing down occurs in either the transverse...

  4. Failure in imperfect anisotropic materials

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang

    2005-01-01

    The fundamental cause of crack growth, namely nucleation and growth of voids, is investigated numerically for a two phase imperfect anisotropic material. A unit cell approach is adopted from which the overall stress strain is evaluated. Failure is observed as a sudden stress drop and depending...

  5. Black Sprayable Molecular Adsorber Coating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This novel molecular adsorber coating would alleviate the size, weight, and complexity issues of traditional molecular adsorber puck.  A flexible tape version...

  6. Adiabatic theory for anisotropic cold molecule collisions

    Energy Technology Data Exchange (ETDEWEB)

    Pawlak, Mariusz [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń (Poland); Shagam, Yuval; Narevicius, Edvardas [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Moiseyev, Nimrod [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Physics, Technion–Israel Institute of Technology, Haifa 32000 (Israel)

    2015-08-21

    We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment {sup 4}He(1s2s {sup 3}S) + HD(1s{sup 2}) → {sup 4}He(1s{sup 2}) + HD{sup +}(1s) + e{sup −} [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings.

  7. Brazilian Tensile Strength of Anisotropic Rocks: Review and New Insights

    Directory of Open Access Journals (Sweden)

    Tianshou Ma

    2018-01-01

    Full Text Available Strength anisotropy is one of the most distinct features of anisotropic rocks, and it also normally reveals strong anisotropy in Brazilian test Strength (“BtS”. Theoretical research on the “BtS” of anisotropic rocks is seldom performed, and in particular some significant factors, such as the anisotropic tensile strength of anisotropic rocks, the initial Brazilian disc fracture points, and the stress distribution on the Brazilian disc, are often ignored. The aim of the present paper is to review the state of the art in the experimental studies on the “BtS” of anisotropic rocks since the pioneering work was introduced in 1964, and to propose a novel theoretical method to underpin the failure mechanisms and predict the “BtS” of anisotropic rocks under Brazilian test conditions. The experimental data of Longmaxi Shale-I and Jixi Coal were utilized to verify the proposed method. The results show the predicted “BtS” results show strong agreement with experimental data, the maximum error is only ~6.55% for Longmaxi Shale-I and ~7.50% for Jixi Coal, and the simulated failure patterns of the Longmaxi Shale-I are also consistent with the test results. For the Longmaxi Shale-I, the Brazilian disc experiences tensile failure of the intact rock when 0° ≤ βw ≤ 24°, shear failure along the weakness planes when 24° ≤ βw ≤ 76°, and tensile failure along the weakness planes when 76° ≤ βw ≤ 90°. For the Jixi Coal, the Brazilian disc experiences tensile failure when 0° ≤ βw ≤ 23° or 76° ≤ βw ≤ 90°, shear failure along the butt cleats when 23° ≤ βw ≤ 32°, and shear failure along the face cleats when 32° ≤ βw ≤ 76°. The proposed method can not only be used to predict the “BtS” and underpin the failure mechanisms of anisotropic rocks containing a single group of weakness planes, but can also be generalized for fractured rocks containing multi-groups of weakness planes.

  8. Pseudorapidity Dependence of Anisotropic Azimuthal Flow with the ALICE Detector

    DEFF Research Database (Denmark)

    Hansen, Alexander Colliander

    In ultra-relativistic heavy-ion collisions a new state of matter known as the strongly interacting quark-gluon plasma (sQGP) is produced. A key observable in the study of the sQGP is anisotropic azimuthal ow. The anisotropies are described by ow harmonics, vn. In this thesis, bias arising from no...... Detector and Silicon Pixel Detector at the CERN Large Hadron Collider (LHC). The results are compared to other LHC experiments andprevious experiments at lower collision energies....

  9. Anisotropic shift of the irreversibility line by neutron irradiation

    International Nuclear Information System (INIS)

    Sauerzopf, F.M.; Wiesinger, H.P.; Weber, H.W.; Crabtree, G.W.; Frischherz, M.C.; Kirk, M.A.

    1991-09-01

    The irreversibility line of high-T c superconductors is shifted considerably by irradiating the material with fast neutrons. The anisotropic and non-monotonous shift is qualitatively explained by a simple model based on an interaction between three pinning mechanisms, the intrinsic pinning by the ab-planes, the weak pinning by the pre-irradiation defect structure, and strong pinning by neutron induced defect cascades. A correlation between the cascade density and the position of the irreversibility line is observed

  10. Pseudorapidity Dependence of Anisotropic Azimuthal Flow with the ALICE Detector

    DEFF Research Database (Denmark)

    Hansen, Alexander Colliander

    In ultra-relativistic heavy-ion collisions a new state of matter known as the strongly interacting quark-gluon plasma (sQGP) is produced. A key observable in the study of the sQGP is anisotropic azimuthal ow. The anisotropies are described by ow harmonics, vn. In this thesis, bias arising from non...... Detector and Silicon Pixel Detector at the CERN Large Hadron Collider (LHC). The results are compared to other LHC experiments andprevious experiments at lower collision energies....

  11. Metafluid with anisotropic dynamic mass

    International Nuclear Information System (INIS)

    Gumen, L.N.; Arriaga, J.; Krokhin, A.A.

    2011-01-01

    We show that a fluid filling the space between metallic cylinders arranged in a two-dimensional lattice exhibits anisotropic dynamic mass for sound waves propagating through the lattice, if its unit cell is anisotropic. Using the plane-waves expansion method we derive (in the long wavelength limit) a formula for the effective mass tensor of the metafluid. The proposed formula is very general - it is valid for arbitrary Bravais lattices and arbitrary filling fractions of the cylinders. We apply our method to a periodic structure with very high anisotropy, when other known methods fail. In particular, we calculate the effective mass tensor for sound waves in air with embedded lattice of aluminum cylinders having rectangular cross sections, and obtain excellent agreement with experiment. The proposed method of calculation may find numerous applications for tailoring of metafluids with prescribed anisotropy.

  12. Anisotropic Ripple Deformation in Phosphorene.

    Science.gov (United States)

    Kou, Liangzhi; Ma, Yandong; Smith, Sean C; Chen, Changfeng

    2015-05-07

    Two-dimensional materials tend to become crumpled according to the Mermin-Wagner theorem, and the resulting ripple deformation may significantly influence electronic properties as observed in graphene and MoS2. Here, we unveil by first-principles calculations a new, highly anisotropic ripple pattern in phosphorene, a monolayer black phosphorus, where compression-induced ripple deformation occurs only along the zigzag direction in the strain range up to 10%, but not the armchair direction. This direction-selective ripple deformation mode in phosphorene stems from its puckered structure with coupled hinge-like bonding configurations and the resulting anisotropic Poisson ratio. We also construct an analytical model using classical elasticity theory for ripple deformation in phosphorene under arbitrary strain. The present results offer new insights into the mechanisms governing the structural and electronic properties of phosphorene crucial to its device applications.

  13. Exact anisotropic polytropic cylindrical solutions

    Science.gov (United States)

    Sharif, M.; Sadiq, Sobia

    2018-03-01

    In this paper, we study anisotropic compact stars with static cylindrically symmetric anisotropic matter distribution satisfying polytropic equation of state. We formulate the field equations as well as the corresponding mass function for the particular form of gravitational potential z(x)=(1+bx)^{η } (η =1, 2, 3) and explore exact solutions of the field equations for different values of the polytropic index. The values of arbitrary constants are determined by taking mass and radius of compact star (Her X-1). We find that resulting solutions show viable behavior of physical parameters (density, radial as well as tangential pressure, anisotropy) and satisfy the stability condition. It is concluded that physically acceptable solutions exist only for η =1, 2.

  14. Anisotropic magnetoresistance and piezoelectric effect in GaAs Hall samples

    Science.gov (United States)

    Ciftja, Orion

    2017-02-01

    Application of a strong magnetic field perpendicular to a two-dimensional electron system leads to a variety of quantum phases ranging from incompressible quantum Hall liquid to Wigner solid, charge density wave, and exotic non-Abelian states. A few quantum phases seen in past experiments on GaAs Hall samples of electrons show pronounced anisotropic magnetoresistance values at certain weak magnetic fields. We argue that this might be due to the piezoelectric effect that is inherent in a semiconductor host such as GaAs. Such an effect has the potential to create a sufficient in-plane internal strain that will be felt by electrons and will determine the direction of high and low resistance. When Wigner solid, charge density wave, and isotropic liquid phases are very close in energy, the overall stability of the system is very sensitive to local order and, thus, can be strongly influenced even by a weak perturbation such as the piezoelectric-induced effective electron-electron interaction, which is anisotropic. In this work, we argue that an anisotropic interaction potential may stabilize anisotropic liquid phases of electrons even in a strong magnetic field regime where normally one expects to see only isotropic quantum Hall or isotropic Fermi liquid states. We use this approach to support a theoretical framework that envisions the possibility of an anisotropic liquid crystalline state of electrons in the lowest Landau level. In particular, we argue that an anisotropic liquid state of electrons may stabilize in the lowest Landau level close to the liquid-solid transition region at filling factor ν =1 /6 for a given anisotropic Coulomb interaction potential. Quantum Monte Carlo simulations for a liquid crystalline state with broken rotational symmetry indicate stability of liquid crystalline order consistent with the existence of an anisotropic liquid state of electrons stabilized by anisotropy at filling factor ν =1 /6 of the lowest Landau level.

  15. X-ray absorption at the L2,3 edge of an anisotropic single crystal: Cadmium (0001)

    International Nuclear Information System (INIS)

    Le Fevre, P.; Magnan, H.; Chandesris, D.

    1996-01-01

    Surface extended x-ray-absorption fine structure (EXAFS) is a very powerful technique for the crystallographic characterization of adsorbed atoms, layers, and thin films. The linear polarization of the synchrotron radiation is used to infer direct information about the crystallographic anisotropy of these systems. For the K absorption edge, the polarization dependence of the EXAFS signal is simple: the contribution of each bond is weighted by a factor cos 2 θ, where θ is the angle between the direction of the bond and the linear polarization of the x rays. For L 2,3 absorption edges, the polarization dependence is more complicated, since the initial p state can be excited to a final state of s or d symmetry. The angular dependences of these two terms are strongly different. We show here, with a study on a bulk anisotropic system, cadmium, that the two terms have to be considered and that neglecting the p to s transitions in the analysis of angular-dependent spectra leads to errors in bond-length determination as high as 0.1 A. copyright 1996 The American Physical Society

  16. Extraction of uranium from sea water by means of fibrous complex adsorbents

    International Nuclear Information System (INIS)

    Miyamatsu, Tokuhisa; Oguchi, Noboru; Kanchiku, Yoshihiko; Aoyagi, Takanobu

    1982-01-01

    Fibrous complex adsorbents for uranium extraction from sea water were prepared by introducing titanic acid or basic zinc carbonate as effective constituents into fibrous ion exchangers. A fibrous chelate type adsorbent was also tested. Among the adsorbents examined, the following ones demonstrated excellent properties for the recovery of uranium from sea water. a) A fibrous, weakly acidic cation exchanger was treated with titanyl sulfate in aqueous sulfuric acid solution, which was followed by neutralization to afford a fibrous adsorbent containing titanic acid (QC-1f(Ti)). The adsorption capacity for uranium in sea water was estimated by extrapolation to be 50μg-U/g-Ad or 1170 μg-U/g-Ti. b) A fibrous, strongly acidic cation exchanger was treated in a similar way to afford another type of fibrous adsorbent with titanic acid incorporated (QCS-Ti). The adsorption capacity was estimated by extrapolation to be 20-30 μg-U/g-Ad. (author)

  17. A simple strategy to realize biomimetic surfaces with controlled anisotropic wetting

    Science.gov (United States)

    Wu, Dong; Chen, Qi-Dai; Yao, Jia; Guan, Yong-Chao; Wang, Jian-Nan; Niu, Li-Gang; Fang, Hong-Hua; Sun, Hong-Bo

    2010-02-01

    The study of anisotropic wetting has become one of the most important research areas in biomimicry. However, realization of controlled anisotropic surfaces remains challenging. Here we investigated anisotropic wetting on grooves with different linewidth, period, and height fabricated by laser interference lithography and found that the anisotropy strongly depended on the height. The anisotropy significantly increased from 9° to 48° when the height was changed from 100 nm to 1.3 μm. This was interpreted by a thermodynamic model as a consequence of the increase of free energy barriers versus the height increase. According to the relationship, controlled anisotropic surfaces were rapidly realized by adjusting the grooves' height that was simply accomplished by changing the resin thickness. Finally, the perpendicular contact angle was further enhanced to 131°±2° by surface modification, which was very close to 135°±3° of a common grass leaf.

  18. Anisotropic and nonlinear optical waveguides

    CERN Document Server

    Someda, CG

    1992-01-01

    Dielectric optical waveguides have been investigated for more than two decades. In the last ten years they have had the unique position of being simultaneously the backbone of a very practical and fully developed technology, as well as an extremely exciting area of basic, forefront research. Existing waveguides can be divided into two sets: one consisting of waveguides which are already in practical use, and the second of those which are still at the laboratory stage of their evolution. This book is divided into two separate parts: the first dealing with anisotropic waveguides, an

  19. Interactions of organic contaminants with mineral-adsorbed surfactants

    Science.gov (United States)

    Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

    2003-01-01

    Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

  20. Nanoscale Rheology and Anisotropic Diffusion Using Single Gold Nanorod Probes

    Science.gov (United States)

    Molaei, Mehdi; Atefi, Ehsan; Crocker, John C.

    2018-03-01

    The complex rotational and translational Brownian motion of anisotropic particles depends on their shape and the viscoelasticity of their surroundings. Because of their strong optical scattering and chemical versatility, gold nanorods would seem to provide the ultimate probes of rheology at the nanoscale, but the suitably accurate orientational tracking required to compute rheology has not been demonstrated. Here we image single gold nanorods with a laser-illuminated dark-field microscope and use optical polarization to determine their three-dimensional orientation to better than one degree. We convert the rotational diffusion of single nanorods in viscoelastic polyethylene glycol solutions to rheology and obtain excellent agreement with bulk measurements. Extensions of earlier models of anisotropic translational diffusion to three dimensions and viscoelastic fluids give excellent agreement with the observed motion of single nanorods. We find that nanorod tracking provides a uniquely capable approach to microrheology and provides a powerful tool for probing nanoscale dynamics and structure in a range of soft materials.

  1. Optical characterization of isotropic and anisotropic layered media

    CERN Document Server

    Jakopic, G

    2000-01-01

    This work deals with the interaction of electromagnetic radiation in the UV/IR region with layered media and the inversion of photometric and ellipsometric spectra. A method is presented how to calculate the dielectric function of an ensemble of different anisotropic oscillators. A way is proposed how to extract both components of the dielectric tensor of uniaxial oligomers out of spectroscopic measurements at normal incidence, if it is possible to make two different structural modifications of the oligomer. Then, effective medium theories with an expansion on anisotropic media are treated and the result is used to model the optical properties of the rough surface of an organic thin film. Further, a new unified analytical inversion of reflectometric and ellipsometric data of strongly absorbing media is presented. A method is shown how to calculate simultaneously the thickness and the optical constants of weakly absorbing films out of one spectroscopic reflection or transmission measurement. The last topic are...

  2. Dynamics of anisotropic power-law f( R) cosmology

    Science.gov (United States)

    Shamir, M. F.

    2016-12-01

    Modified theories of gravity have attracted much attention of the researchers in the recent years. In particular, the f( R) theory has been investigated extensively due to important f( R) gravity models in cosmological contexts. This paper is devoted to exploring an anisotropic universe in metric f( R) gravity. A locally rotationally symmetric Bianchi type I cosmological model is considered for this purpose. Exact solutions of modified field equations are obtained for a well-known f( R) gravity model. The energy conditions are also discussed for the model under consideration. The viability of the model is investigated via graphical analysis using the present-day values of cosmological parameters. The model satisfies null energy, weak energy, and dominant energy conditions for a particular range of the anisotropy parameter while the strong energy condition is violated, which shows that the anisotropic universe in f( R) gravity supports the crucial issue of accelerated expansion of the universe.

  3. Theoretical Investigation of Anisotropic Damping in Exchange Bias Systems

    Science.gov (United States)

    Farrar, Alison; Beik Mohammadi, Jamileh; Mewes, Tim; Mewes, Claudia

    An accurate description of the magnetization dynamics of exchange bias systems is essential for further development of computer read heads and STT-MRAM. There have been several theoretical predictions of an anisotropic Gilbert damping tensor, influenced by the symmetry of the crystal structure, in place of the scalar Gilbert damping parameter in the Landau-Lifshitz-Gilbert equation of motion. However, experimental confirmation is difficult as the anisotropy of the damping parameter is expected to be small for single crystals. We follow up on our experimental discovery of a strong unidirectional contribution to the relaxation of exchange bias systems by implementing an anisotropic damping tensor in our Matlab-based micromagnetics code M3. We present results for a damping tensor with unidirectional anisotropy with respect to the instantaneous orientation of the magnetization. NSF-CAREER No 1452670 and 0952929, UA Computer-Based Honors Program.

  4. Ballistic Anisotropic Magnetoresistance of Single-Atom Contacts.

    Science.gov (United States)

    Schöneberg, J; Otte, F; Néel, N; Weismann, A; Mokrousov, Y; Kröger, J; Berndt, R; Heinze, S

    2016-02-10

    Anisotropic magnetoresistance, that is, the sensitivity of the electrical resistance of magnetic materials on the magnetization direction, is expected to be strongly enhanced in ballistic transport through nanoscale junctions. However, unambiguous experimental evidence of this effect is difficult to achieve. We utilize single-atom junctions to measure this ballistic anisotropic magnetoresistance (AMR). Single Co and Ir atoms are deposited on domains and domain walls of ferromagnetic Fe layers on W(110) to control their magnetization directions. They are contacted with nonmagnetic tips in a low-temperature scanning tunneling microscope to measure the junction conductances. Large changes of the magnetoresistance occur from the tunneling to the ballistic regime due to the competition of localized and delocalized d-orbitals, which are differently affected by spin-orbit coupling. This work shows that engineering the AMR at the single atom level is feasible.

  5. Effect of adsorbents and chemical treatments on the removal of strontium from aqueous solutions

    International Nuclear Information System (INIS)

    Ahmadpour, A.; Zabihi, M.; Tahmasbi, M.; Bastami, T. Rohani

    2010-01-01

    In the present investigation, three different solid wastes namely almond green hull, eggplant hull, and moss were initially treated and used as adsorbents for the adsorption of strontium ion from aqueous solutions. Adsorbent types and chemical treatments are proved to have effective roles on the adsorption of Sr(II) ion. Among the three adsorbents, almond green hull demonstrated strong affinity toward strontium ion in different solutions. The effectiveness of this new adsorbent was studied in batch adsorption mode under a variety of experimental conditions such as: different chemical treatments, various amounts of adsorbent, and initial metal-ion concentration. The optimum doses of adsorbent for the maximum Sr(II) adsorption were found to be 0.2 and 0.3 g for 45 and 102 mg L -1 solutions, respectively. High Sr(II) adsorption efficiencies were achieved only in the first 3 min of adsorbent's contact time. The kinetics of Sr(II) adsorption on almond green hull was also examined and it was observed that it follows the pseudo second-order behavior. Both Langmuir and Freundlich models well predicted the experimental adsorption isotherm data. The maximum adsorption capacity on almond green hull was found to be 116.3 mg g -1 . The present study also confirmed that these low cost agriculture byproducts could be used as efficient adsorbents for the removal of strontium from wastewater streams.

  6. Influence of hydrophobization of fumed oxides on interactions with polar and nonpolar adsorbates

    Science.gov (United States)

    Gun'ko, V. M.; Pakhlov, E. M.; Goncharuk, O. V.; Andriyko, L. S.; Marynin, A. I.; Ukrainets, A. I.; Charmas, B.; Skubiszewska-Zięba, J.; Blitz, J. P.

    2017-11-01

    A variety of unmodified and modified fumed silica A-300 and silica/titania (ST20 and ST76 at 20 and 76 wt.% of titania, respectively) was prepared to analyze features of their interactions with polar and nonpolar adsorbates. The materials were studied using nitrogen adsorption-desorption, ethanol evaporation kinetics, infrared (IR) spectroscopy, thermogravimetry (TG), photon correlation spectroscopy, differential scanning calorimetry (DSC), DSC and TG thermoporometry, and quantum chemistry. Changes in surface structure of modified nanooxides with increasing hydrophobization degree (ΘMS) from 20% to 100% have a strong affect on the textural characteristics of the materials and adsorption-desorption of various adsorbates. Confined space effects enhanced due to the location of adsorbates in narrow voids between nanoparticles lead to freezing-melting point depression for bound polar and nonpolar adsorbates. The behavior of particles of modified nanooxides in aqueous and water/ethanol media is strongly altered due to enhanced aggregations with increasing value of ΘMS. All of these change are non-monotonic functions of ΘMS which affects (i) rearrangement of nanoparticles, (ii) interactions with polar and nonpolar adsorbates, (iii) location of adsorbates in voids of different sizes, (iv) the clustering of adsorbates and formation of nearly bulk structures.

  7. Anisotropic non-Fermi liquids

    Science.gov (United States)

    Sur, Shouvik; Lee, Sung-Sik

    2016-11-01

    We study non-Fermi-liquid states that arise at the quantum critical points associated with the spin density wave (SDW) and charge density wave (CDW) transitions in metals with twofold rotational symmetry. We use the dimensional regularization scheme, where a one-dimensional Fermi surface is embedded in (3 -ɛ ) -dimensional momentum space. In three dimensions, quasilocal marginal Fermi liquids arise both at the SDW and CDW critical points: the speed of the collective mode along the ordering wave vector is logarithmically renormalized to zero compared to that of Fermi velocity. Below three dimensions, however, the SDW and CDW critical points exhibit drastically different behaviors. At the SDW critical point, a stable anisotropic non-Fermi-liquid state is realized for small ɛ , where not only time but also different spatial coordinates develop distinct anomalous dimensions. The non-Fermi liquid exhibits an emergent algebraic nesting as the patches of Fermi surface are deformed into a universal power-law shape near the hot spots. Due to the anisotropic scaling, the energy of incoherent spin fluctuations disperse with different power laws in different momentum directions. At the CDW critical point, on the other hand, the perturbative expansion breaks down immediately below three dimensions as the interaction renormalizes the speed of charge fluctuations to zero within a finite renormalization group scale through a two-loop effect. The difference originates from the fact that the vertex correction antiscreens the coupling at the SDW critical point whereas it screens at the CDW critical point.

  8. Reflection of light from an anisotropic medium

    OpenAIRE

    Ignatovich, Filipp V.; Ignatovich, Vladimir

    2010-01-01

    We present here a general approach to treat reflection and refraction of light of arbitrary polarization from single axis anisotropic plates. We show that reflection from interface inside the anisotropic medium is accompanied by beam splitting and can create surface waves.

  9. Filter-adsorber aging assessment

    Energy Technology Data Exchange (ETDEWEB)

    Winegardner, W.K. [Pacific Northwest Laboratory, Richland, WA (United States)

    1995-02-01

    An aging assessment of high-efficiency particulate (HEPA) air filters and activated carbon gas adsorption units was performed by the Pacific Northwest Laboratory as part of the U.S. Nuclear Regulatory Commission`s (USNRC) Nuclear Plant Aging Research (NPAR) Program. This evaluation of the general process in which characteristics of these two components gradually change with time or use included the compilation of information concerning failure experience, stressors, aging mechanisms and effects, and inspection, surveillance, and monitoring methods (ISMM). Stressors, the agents or stimuli that can produce aging degradation, include heat, radiation, volatile contaminants, and even normal concentrations of aerosol particles and gasses. In an experimental evaluation of degradation in terms of the tensile breaking strength of aged filter media specimens, over forty percent of the samples did not meet specifications for new material. Chemical and physical reactions can gradually embrittle sealants and gaskets as well as filter media. Mechanisms that can lead to impaired adsorber performance are associated with the loss of potentially available active sites as a result of the exposure of the carbon to airborne moisture or volatile organic compounds. Inspection, surveillance, and monitoring methods have been established to observe filter pressure drop buildup, check HEPA filters and adsorbers for bypass, and determine the retention effectiveness of aged carbon. These evaluations of installed filters do not reveal degradation in terms of reduced media strength but that under normal conditions aged media can continue to effectively retain particles. However, this degradation may be important when considering the likelihood of moisture, steam, and higher particle loadings during severe accidents and the fact it is probable that the filters have been in use for an extended period.

  10. Efficient Wavefield Extrapolation In Anisotropic Media

    KAUST Repository

    Alkhalifah, Tariq

    2014-07-03

    Various examples are provided for wavefield extrapolation in anisotropic media. In one example, among others, a method includes determining an effective isotropic velocity model and extrapolating an equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. The effective isotropic velocity model can be based upon a kinematic geometrical representation of an anisotropic, poroelastic or viscoelastic wavefield. Extrapolating the equivalent propagation can use isotopic, acoustic or elastic operators based upon the determined effective isotropic velocity model. In another example, non-transitory computer readable medium stores an application that, when executed by processing circuitry, causes the processing circuitry to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. In another example, a system includes processing circuitry and an application configured to cause the system to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield.

  11. Ecological applications of the irradiated adsorbents

    International Nuclear Information System (INIS)

    Tusseyev, T.

    2004-01-01

    Full text: In our previous works it was shown that after irradiation some adsorbents gain new interesting properties such as increasing (or decreasing) of their adsorption capacity, selectivity in relation to some gases, change of chemical bounds of gas molecules with adsorbent surface as well as other properties. We investigated a lot of adsorbents with semiconducting and dielectric properties. A high temperature superconductor was investigated also. Adsorbents were irradiated by ultraviolet (UV) and gamma - radiation, reactor (n.γ) - radiation, α-particles (E=40-50 MeV), protons ( E=30 MeV), and also He-3 ions (E-29-60 MeV). The following techniques were used: volumetric (manometrical), mass-spectrometer and IR spectroscopic methods, and also method of electronic - paramagnetic resonance (spin paramagnetic resonance) The obtained results allow to speak about creation of new adsorbents for gas purification (clearing) from harmful impurities, gas selection into components, an increasing of adsorbing surface. Thus one more advantage of the irradiated adsorbents is that they have 'memory effect', i.e. they can be used enough long time after irradiation. In laboratory conditions we built the small-sized adsorptive pump on the basis of the irradiated zeolites which are capable to work in autonomous conditions. It was found, that some of adsorbents after irradiation gain (or lose) selectivity in relation to definite gases. So, silica gel, which one in initial state does not adsorb hydrogen, after gamma irradiation it becomes active in relation to hydrogen. Some of rare earths oxides also show selectivity in relation to hydrogen and oxygen depending on a type of irradiation. Thus, it is possible to create different absorbents, depending on a solved problem, using a way or selection of adsorbents, either of radiation type and energy, as a result obtained adsorbents can be used for various ecological purposes

  12. Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Chris [ORNL; Yatsandra, Oyola [ORNL; Mayes, Richard [ORNL; none,; Gill, Gary [PNNL; Li-Jung, Kuo [PNNL; Wood, Jordana [PNNL; Sadananda, Das [ORNL

    2014-04-30

    ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

  13. Reinterpreting aircraft measurements in anisotropic scaling turbulence

    Directory of Open Access Journals (Sweden)

    S. J. Hovde

    2009-07-01

    Full Text Available Due to both systematic and turbulent induced vertical fluctuations, the interpretation of atmospheric aircraft measurements requires a theory of turbulence. Until now virtually all the relevant theories have been isotropic or "quasi isotropic" in the sense that their exponents are the same in all directions. However almost all the available data on the vertical structure shows that it is scaling but with exponents different from the horizontal: the turbulence is scaling but anisotropic. In this paper, we show how such turbulence can lead to spurious breaks in the scaling and to the spurious appearance of the vertical scaling exponent at large horizontal lags.

    We demonstrate this using 16 legs of Gulfstream 4 aircraft near the top of the troposphere following isobars each between 500 and 3200 km in length. First we show that over wide ranges of scale, the horizontal spectra of the aircraft altitude are nearly k-5/3. In addition, we show that the altitude and pressure fluctuations along these fractal trajectories have a high degree of coherence with the measured wind (especially with its longitudinal component. There is also a strong phase relation between the altitude, pressure and wind fluctuations; for scales less than ≈40 km (on average the wind fluctuations lead the pressure and altitude, whereas for larger scales, the pressure fluctuations leads the wind. At the same transition scale, there is a break in the wind spectrum which we argue is caused by the aircraft starting to accurately follow isobars at the larger scales. In comparison, the temperature and humidity have low coherencies and phases and there are no apparent scale breaks, reinforcing the hypothesis that it is the aircraft trajectory that is causally linked to the scale breaks in the wind measurements.

    Using spectra and structure functions for the wind, we then estimate their exponents (β, H at small (5/3, 1/3 and large scales (2

  14. Thermodynamics of gas adsorption on solid adsorbents

    International Nuclear Information System (INIS)

    Budrugeac, P.

    1979-01-01

    Starting with several hypotheses about the adsorbtion system and the adsorption phenomenon, a thermodynamic treatment of gas adsorption on solid adsorbants is presented. The relationships for determination from isotherms and calorimetric data of thermodynamic functions are derived. The problem of the phase changes in adsorbed layer is discussed. (author)

  15. adsorbent for defluoridation of drinking water

    African Journals Online (AJOL)

    2014-12-17

    Dec 17, 2014 ... In this study, the performance of different aluminium hydroxide–based adsorbents was compared in terms of fluoride adsorption capacity, potential for repetitive regeneration, surface acidity and surface site concentrations. The adsorbents were aluminium hydro(oxide) (AO), activated alumina (AA), and ...

  16. Extraction of uranium from seawater by the fibrous composite adsorbent

    International Nuclear Information System (INIS)

    Katoh, Shunsaku; Sugasaka, Kazuhiko; Nogi, Tatsuo; Yoshizumi, Nobuo; Mima, Kooji.

    1986-01-01

    The fibrous composite adsorbents consisting of hydrous titanium oxide and activated carbon were prepared with hydrophilic polyacrylonitrile system polymer as a binder under various conditions, and the adsorptive property of the fibrous composite adsorbents for uranium from seawater was examined. The fibrous composite adsorbents which spun under high pressure (10 kg/cm 2 ) was the finest having the largest pore volume. In addition, the amount of uranium adsorbed of the fibrous adsorbent was the largest. The rate of uranium adsorption by the fibrous adsorbent was the same as the rate of uranium adsorption by the powdery adsorbent. The excellent fibrous adsorbent adsorbed 0.23 mg U/g adsorbent for 10 d and 0.65 mg U/g adsorbent for 100 d. The rate of uranium desorption from the fibrous adsorbent by alkali carbonate solution was large, and the uranium in the fibrous adsorbent desorbed 75 % for 8 h and about 100 % for 24 h. (author)

  17. An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lingling, E-mail: lasier_wang@hotmail.com [College of Chemical Engineering and Materials, Quanzhou Normal University, Quanzhou 362000, Fujian (China); Environmental Engineering and Science Program, 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Han, Changseok [ORISE Post-doctoral Fellow, The U.S. Environmental Protection Agency, ORD, NRMRL, STD, CPB, 26 W. Martin Luther King Jr. Drive, Cincinnati, OH 45268 (United States); Nadagouda, Mallikarjuna N. [The U.S. Environmental Protection Agency, ORD, NRMRL, WSWRD, WQMB, 26 W. Martin Luther King Jr. Drive, Cincinnati, OH 45268 (United States); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Nireas-International Water Research Centre, School of Engineering, University of Cyprus, PO Box 20537, 1678, Nicosia (Cyprus)

    2016-08-05

    Highlights: • An innovative adsorbent was successfully synthesized to remove humic acid. • The adsorbent possessed high adsorption capacity for humic acid. • The adsorption capacity remarkably increased after an acid modification. • The adsorption capacity was proportional to the amount of ZnO coated on zeolite. • Electrostatic interactions are a major factor at the first stage of the process. - Abstract: Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO{sub 3}){sub 2}·6H{sub 2}O functionalization of zeolite 4A. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The synthesized materials were characterized by porosimetry analysis, scanning electron microscopy, X-Ray diffraction analysis, and high resolution transmission electron microscopy. The maximum adsorption capacity of the adsorbents at 21 ± 1 °C was about 60 mgC g{sup −1}. The results showed that the positive charge density of ZnO-coated zeolite adsorbents was proportional to the amount of ZnO coated on zeolite and thus, ZnO-coated zeolite adsorbents exhibited a greater affinity for negatively charged ions. Furthermore, the adsorption capacity of ZnO-coated zeolite adsorbents increased markedly after acid modification. Adsorption experiments demonstrated ZnO-coated zeolite adsorbents possessed high adsorption capacity to remove HA from aqueous solutions mainly due to strong electrostatic interactions between negative functional groups of HA and the positive charges of ZnO-coated zeolite adsorbents.

  18. Isothermal anisotropic magnetoresistance in antiferromagnetic metallic IrMn.

    Science.gov (United States)

    Galceran, R; Fina, I; Cisneros-Fernández, J; Bozzo, B; Frontera, C; López-Mir, L; Deniz, H; Park, K-W; Park, B-G; Balcells, Ll; Martí, X; Jungwirth, T; Martínez, B

    2016-10-20

    Antiferromagnetic spintronics is an emerging field; antiferromagnets can improve the functionalities of ferromagnets with higher response times, and having the information shielded against external magnetic field. Moreover, a large list of aniferromagnetic semiconductors and metals with Néel temperatures above room temperature exists. In the present manuscript, we persevere in the quest for the limits of how large can anisotropic magnetoresistance be in antiferromagnetic materials with very large spin-orbit coupling. We selected IrMn as a prime example of first-class moment (Mn) and spin-orbit (Ir) combination. Isothermal magnetotransport measurements in an antiferromagnetic-metal(IrMn)/ferromagnetic-insulator thin film bilayer have been performed. The metal/insulator structure with magnetic coupling between both layers allows the measurement of the modulation of the transport properties exclusively in the antiferromagnetic layer. Anisotropic magnetoresistance as large as 0.15% has been found, which is much larger than that for a bare IrMn layer. Interestingly, it has been observed that anisotropic magnetoresistance is strongly influenced by the field cooling conditions, signaling the dependence of the found response on the formation of domains at the magnetic ordering temperature.

  19. Modeling diffusion of adsorbed polymer with explicit solvent.

    Science.gov (United States)

    Desai, Tapan G; Keblinski, Pawel; Kumar, Sanat K; Granick, Steve

    2007-05-25

    Computer simulations of a polymer chain of length N strongly adsorbed at the solid-liquid interface in the presence of explicit solvent are used to delineate the factors affecting the N dependence of the polymer lateral diffusion coefficient, D(||). We find that surface roughness has a large influence, and D(||) scales as D(||) approximately N(-x), with x approximately 3/4 and x approximately 1 for ideal smooth and corrugated surfaces, respectively. The first result is consistent with the hydrodynamics of a "particle" of radius of gyration R(G) approximately N(nu) (nu=0.75) translating parallel to a planar interface, while the second implies that the friction of the adsorbed chains dominates. These results are discussed in the context of recent measurements.

  20. Warm anisotropic inflationary universe model

    International Nuclear Information System (INIS)

    Sharif, M.; Saleem, Rabia

    2014-01-01

    This paper is devoted to the study of warm inflation using vector fields in the background of a locally rotationally symmetric Bianchi type I model of the universe. We formulate the field equations, and slow-roll and perturbation parameters (scalar and tensor power spectra as well as their spectral indices) in the slow-roll approximation. We evaluate all these parameters in terms of the directional Hubble parameter during the intermediate and logamediate inflationary regimes by taking the dissipation factor as a function of the scalar field as well as a constant. In each case, we calculate the observational parameter of interest, i.e., the tensor-scalar ratio in terms of the inflaton. The graphical behavior of these parameters shows that the anisotropic model is also compatible with WMAP7 and the Planck observational data. (orig.)

  1. Warm anisotropic inflationary universe model

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M.; Saleem, Rabia [University of the Punjab, Department of Mathematics, Lahore (Pakistan)

    2014-02-15

    This paper is devoted to the study of warm inflation using vector fields in the background of a locally rotationally symmetric Bianchi type I model of the universe. We formulate the field equations, and slow-roll and perturbation parameters (scalar and tensor power spectra as well as their spectral indices) in the slow-roll approximation. We evaluate all these parameters in terms of the directional Hubble parameter during the intermediate and logamediate inflationary regimes by taking the dissipation factor as a function of the scalar field as well as a constant. In each case, we calculate the observational parameter of interest, i.e., the tensor-scalar ratio in terms of the inflaton. The graphical behavior of these parameters shows that the anisotropic model is also compatible with WMAP7 and the Planck observational data. (orig.)

  2. Finite-volume scheme for anisotropic diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Es, Bram van, E-mail: bramiozo@gmail.com [Centrum Wiskunde & Informatica, P.O. Box 94079, 1090GB Amsterdam (Netherlands); FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands); Koren, Barry [Eindhoven University of Technology (Netherlands); Blank, Hugo J. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands)

    2016-02-01

    In this paper, we apply a special finite-volume scheme, limited to smooth temperature distributions and Cartesian grids, to test the importance of connectivity of the finite volumes. The area of application is nuclear fusion plasma with field line aligned temperature gradients and extreme anisotropy. We apply the scheme to the anisotropic heat-conduction equation, and compare its results with those of existing finite-volume schemes for anisotropic diffusion. Also, we introduce a general model adaptation of the steady diffusion equation for extremely anisotropic diffusion problems with closed field lines.

  3. Environmentally Friendly in Situ Regeneration of Graphene Aerogel as a Model Conductive Adsorbent.

    Science.gov (United States)

    Pan, Meilan; Shan, Chao; Zhang, Xiaolin; Zhang, Yanyang; Zhu, Chanyuan; Gao, Guandao; Pan, Bingcai

    2018-01-16

    Adsorption is a classical process widely used in industry and environmental protection, and the regeneration of exhausted adsorbents, as the reverse process of adsorption, is vital to achieving a sustainable adsorption process. Chemical and thermal regeneration, which feature high costs and environmental side effects, are classical but not environmentally friendly methods. Herein, a new regeneration method based on an electrochemical process using graphene aerogel (GA) as a model conductive adsorbent was proposed. First, 3D GA was prepared to adsorb organic and inorganic pollutants, avoiding the inconvenience of using powdered graphene. Then, the exhausted GA was cleaned by the electrochemical desorption and degradation of adsorbed organic pollutants if undesired and the electrorepulsion of adsorbed metal ions in the absence of any additional chemicals, showing a high processing capability of 1.21 L g -1 GA h -1 and low energy consumption (∼0.2 kWh m -3 solution). The mechanisms involved in the electrochemistry-induced desorption process cover a decline in the GA adsorption performance depended on the electrochemically adjustable surface charge conditions, and the further repulsion and migration of adsorbates is subject to the strong in situ electric field. This work has important implications for the development of environmentally friendly regeneration processes and qualified adsorbents as well as the application of a green and efficient regeneration concept for traditional adsorption processes.

  4. Heat transfer to the adsorbent in solar adsorption cooling device

    Science.gov (United States)

    Pilat, Peter; Patsch, Marek; Papucik, Stefan; Vantuch, Martin

    2014-08-01

    The article deals with design and construction of solar adsorption cooling device and with heat transfer problem in adsorber. The most important part of adsorption cooling system is adsorber/desorber containing adsorbent. Zeolith (adsorbent) type was chosen for its high adsorption capacity, like a coolant was used water. In adsorber/desorber occur, at heating of adsorbent, to heat transfer from heat change medium to the adsorbent. The time required for heating of adsorber filling is very important, because on it depend flexibility of cooling system. Zeolith has a large thermal resistance, therefore it had to be adapted the design and construction of adsorber. As the best shows the tube type of adsorber with double coat construction. By this construction is ensured thin layer of adsorbent and heating is quick in all volume of adsorbent. The process of heat transfer was experimentally measured, but for comparison simulated in ANSYS, too.

  5. Anisotropic tunneling resistance in a phosphorene-based magnetic barrier

    Science.gov (United States)

    Zhai, Feng; Hu, Wei; Lu, Junqiang

    2017-10-01

    We investigate the ballistic tunneling transport properties of a monolayer of black phosphorus under a magnetic barrier. The conductance of the system depends strongly on the orientation of the magnetic barrier, which is suppressed maximally when the magnetic barrier is oriented along the armchair direction. The mechanism relies on the highly anisotropic energy dispersion of phosphorene and the magnetic-barrier-induced suppression of available phase space for transmission. The magnetoresistance is enhanced by the reduction of the band gap under the same effective mass components.

  6. Viscous anisotropic hydrodynamics for the Gubser flow

    Science.gov (United States)

    Martinez, M.; McNelis, M.; Heinz, U.

    2017-11-01

    In this work we describe the dynamics of a highly anisotropic system undergoing boost-invariant longitudinal and azimuthally symmetric radial expansion (Gubser flow) for arbitrary shear viscosity to entropy density ratio. We derive the equations of motion of dissipative anisotropic hydrodynamics by applying to this situation the moments method recently derived by Molnár et al. (MNR) [E. Molnar, H. Niemi, and D. H. Rischke, "Derivation of anisotropic dissipative fluid dynamics from the Boltzmann equation," Phys. Rev. D93 no. 11, (2016) 114025, arxiv:arXiv:1602.00573 [nucl-th], E. Molnar, H. Niemi, and D. H. Rischke, "Closing the equations of motion of anisotropic fluid dynamics by a judicious choice of a moment of the Boltzmann equation," Phys. Rev. D94 no. 12, (2016) 125003, arxiv:arXiv:1606.09019 [nucl-th

  7. Anisotropic magnetoresistance in a Fermi glass

    International Nuclear Information System (INIS)

    Ovadyahu, Z.; Physics Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel 84120)

    1986-01-01

    Insulating thin films of indium oxide exhibit negative, anisotropic magnetoresistance. The systematics of these results imply that the magnetoresistance mechanism may give different weight to the distribution of the localization lengths than that given by the hopping conductivity

  8. Electronically driven adsorbate excitation mechanism in femtosecond-pulse laser desorption

    DEFF Research Database (Denmark)

    Brandbyge, Mads; Hedegård, Per; Heinz, T. F.

    1995-01-01

    a systematic theoretical treatment of this coupling process in the language of an electronic friction, which generates Langevin noise in the adsorbate center-of-mass degrees of freedom, while the electronic degrees of freedom are at a high temperature. Starting from an influence-functional path......-integral description, a simple formula for the electronic friction is defined which is valid at all electronic temperatures. At low temperatures the formalism makes contact with the electronic friction appearing in the theory of adsorbate vibrational damping, whereas at high temperatures comparable with the adsorbate...... electronic excitation energies the friction becomes strongly temperature dependent due to dominance by virtual excitations between different adsorbate potential energy surfaces. The former regime is related to the electronic friction model for the desorption process, and the latter to the desorption induced...

  9. Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry.

    Science.gov (United States)

    Silber, David; Kowalski, Piotr M; Traeger, Franziska; Buchholz, Maria; Bebensee, Fabian; Meyer, Bernd; Wöll, Christof

    2016-09-30

    Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO 2 (110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO 2 (110) surface.

  10. Modelling Coulomb Collisions in Anisotropic Plasmas

    Science.gov (United States)

    Hellinger, P.; Travnicek, P. M.

    2009-12-01

    Collisional transport in anisotropic plasmas is investigated comparing the theoretical transport coefficients (Hellinger and Travnicek, 2009) for anisotropic particles with the results of the corresponding Langevin equation, obtained as a generalization of Manheimer et al. (1997). References: Hellinger, P., and P. M. Travnicek (2009), On Coulomb collisions in bi-Maxwellian plasmas, Phys. Plasmas, 16, 054501. Manheimer, W. M., M. Lampe and G. Joyce (1997), Langevin representation of Coulomb collisions in PIC simulations, J. Comput. Phys., 138, 563-584.

  11. Anisotropic rectangular metric for polygonal surface remeshing

    KAUST Repository

    Pellenard, Bertrand

    2013-06-18

    We propose a new method for anisotropic polygonal surface remeshing. Our algorithm takes as input a surface triangle mesh. An anisotropic rectangular metric, defined at each triangle facet of the input mesh, is derived from both a user-specified normal-based tolerance error and the requirement to favor rectangle-shaped polygons. Our algorithm uses a greedy optimization procedure that adds, deletes and relocates generators so as to match two criteria related to partitioning and conformity.

  12. Penetration effect in uniaxial anisotropic metamaterials

    Science.gov (United States)

    Vytovtov, K.; Barabanova, E.; Zouhdi, S.

    2018-02-01

    Plane harmonic wave propagation along an interface between vacuum and a semi-infinite anisotropic metamaterial is considered. Possibility of penetration effect in the considered case is studied. It is shown that there is a bulk wave within the anisotropic metamaterial with an arbitrary orientation of the anisotropy axis. It is also proved that a reflected wave must propagate perpendicularly to the interface in the case of the extraordinary wave. Moreover, no wave is reflected in the case of ordinary wave propagation.

  13. Nontopological Saddle-Splay and Curvature Instabilities from Anisotropic Membrane Inclusions

    Science.gov (United States)

    Fournier, J. B.

    1996-06-01

    Anisotropic inclusions are shown to induce spontaneous deviatoric bendings in lipidic membranes, by orienting at right angles across the bilayer. In the limit of strong membrane curvatures, a nonanalytical bending energy term is generated that favors saddlelike and cylindrical shapes, without penalizing spherical ones. An ``egg-carton'' instability results in flat membranes as well as a wormlike shape instability for vesicles.

  14. Alkali metal adsorbate sputtering by molecular impact

    International Nuclear Information System (INIS)

    Moran, J.P.; Wachman, H.Y.; Trilling, L.

    1974-01-01

    An exploratory study of the sputtering by a krypton molecular beam of rubidium adsorbed at low coverage on a tungsten substrate has been described in a previous paper. An extension of this work is reported now

  15. Black Sprayable Molecular Adsorber Coating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The main objective of this technology project is to develop, optimize, and flight qualify a black version of the molecular adsorber coating and a conductive version...

  16. PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

    Science.gov (United States)

    Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

  17. The Dynamics and Structures of Adsorbed Surfaces

    DEFF Research Database (Denmark)

    Nielsen, M; Ellenson, W. D.; McTague, J. P.

    1978-01-01

    Reviews neutron scattering work performed on films of simple gas atoms and molecules adsorbed primarily on graphite surfaces. Exfoliated graphite substrates such as Grafoil were first used in this kind of measurements about five years ago and new results have been reported at an increasing pace....... Elastic neutron diffraction measurements, determining the two-dimensional structural ordering of the adsorbed films, have been performed on layers of N2, Ar, H2, D2, O2, Kr, and He. Measurements on layers of larger molecules such as CD4 and ND3 have also been reported. Inelastic neutron scattering...... of molecules such as NH3 or the internal modes of adsorbed molecules such as C4H10. Neutron scattering measurements where substrates other than graphite products are used as the adsorbents will not be reviewed here. However, the power of the technique will be demonstrated in an example of H2 physisorbed...

  18. New liquid waste control with tannin adsorbent

    International Nuclear Information System (INIS)

    Nakamura, Yoshinobu; Shirato, Wataru; Nakamura, Yasuo

    1998-01-01

    Since 1971, the Mitsubishi Nuclear Fuel Co., Ltd. (MNF) has been fabricating PWR fuels and developing related technology and processes. In the UF 6 reconversion lines of MNF, the ammonium diuranate (ADU) process has been operating and the newly developed process of liquid waste treatment was installed last year. The characteristic of this process is to use insoluble tannin adsorbent which has been developed by MNF. The tannin adsorbent is not only an effective means to adsorb heavy metals such as uranium and plutonium but is also easy to incinerate at low temperature. Control of radioactive liquid waste from nuclear facilities is generally implemented by co-precipitation. However, it produces secondary wastes such as noncombustible materials which include radionuclides and it is anticipated that the storage and disposal of those wastes will be at high cost. Those are the reasons why tannin adsorbent has an advantage, and why MNF develops it. (author)

  19. Mechanics of anisotropic spring networks.

    Science.gov (United States)

    Zhang, T; Schwarz, J M; Das, Moumita

    2014-12-01

    We construct and analyze a model for a disordered linear spring network with anisotropy. The modeling is motivated by, for example, granular systems, nematic elastomers, and ultimately cytoskeletal networks exhibiting some underlying anisotropy. The model consists of a triangular lattice with two different bond occupation probabilities, p(x) and p(y), for the linear springs. We develop an effective medium theory (EMT) to describe the network elasticity as a function of p(x) and p(y). We find that the onset of rigidity in the EMT agrees with Maxwell constraint counting. We also find beyond linear behavior in the shear and bulk modulus as a function of occupation probability in the rigid phase for small strains, which differs from the isotropic case. We compare our EMT with numerical simulations to find rather good agreement. Finally, we discuss the implications of extending the reach of effective medium theory as well as draw connections with prior work on both anisotropic and isotropic spring networks.

  20. Rotational discontinuities in anisotropic plasmas

    International Nuclear Information System (INIS)

    Omidi, N.

    1992-01-01

    The kinetic structure of rotational discontinuities (RDs) in anisotropic plasmas with T perpendicular /T parallel > 1 is investigated by using a one-dimensional electromagnetic hybrid code. To form the RD, a new approach is used where the plasma is injected from one boundary and reflected from the other, resulting in the generation of a traveling fast shock and an RD. Unlike the previously used methods, no a priori assumptions are made regarding the initial structure (i.e. width or sense of rotation) of the rotational discontinuity. The results show that across the RD both the magnetic field strength and direction, as well as the plasma density change. Given that such a change can also be associated with an intermediate shock, the Rankine-Hugoniot relations are used to confirm that the observed structures are indeed RDs. It is found that the thickness of RDs is a few ion inertial lengths and is independent of the rotation angle. Also, the preferred sense of rotation is in the electron sense; however, RDs with a rotation angle larger than 180 degree are found to be unstable, changing their rotation to a stable ion sense

  1. NOx Removal and Effect of Adsorbate-Adsorbate Interactions

    DEFF Research Database (Denmark)

    Khan, Tuhin Suvra

    to obtain more accurate catalytic rates than with the commonly used non-interacting mean field model. I then applied the proposed adsorbate-adsorbate interaction model to three important catalytic reactions, the direct NO decomposition, CO methanation, and steam reforming of methane, and analyzed the effect...... these challenges systematically and have developed some new methods and models to counter those challenges and obtain some general understanding of the catalytic process. I have developed an adsorbate-adsorbate interaction model to include the coverage dependency of the adsorption energy in kinetic models...... of adsorbate-adsorbate interactions on their catalytic rates. An alloy screening method has also been developed to screen for the industrially most promising alloy catalysts for any catalytic reaction. I have also studied the structure sensitivity of the rates of catalytic direct NO decomposition on different...

  2. Dissolved Air Flotation of arsenic adsorbent particles

    Directory of Open Access Journals (Sweden)

    Mario Enrique Santander Muñoz

    2015-01-01

    Full Text Available The removal of arsenic from synthetic effluent was studied using the adsorbent particle flotation technique (APF and dissolved air flotation (DAF. A sample of an iron mineral was used as adsorbent particles of arsenic, ferric chloride as coagulant, cationic poly-acrylamide (NALCO 9808 as flocculants, and sodium oleate as collector. Adsorption studies to determine the pH influence, contact time, and adsorbent particles concentration on the adsorption of arsenic were carried out along with flotation studies to determine the removal efficiency of adsorbents particles. The results achieved indicate that the adsorption kinetic of arsenic is very rapid and that in range of pH’s from 2 to 7 the adsorption percentages remain constant. The equilibrium conditions were achieved in 60 minutes and about 95% of arsenic was adsorbed when used an adsorbent concentration of 2 g/L and pH 6.3. The maximum adsorption capacity of adsorbent particles was 4.96 mg/g. The mean free energy of adsorption (E was found to be 2.63 kJ/mol, which suggests physisorption. The results of the flotation studies demonstrated that when synthetic effluents with 8.9 mg/L of arsenic were treated under the following experimental conditions; 2 g/L of adsorbent particles, 120 mg/L of Fe(III, 2 mg/L of Nalco 9808, 20 mg/L of sodium oleate, and 40% of recycle ratio in the DAF, it was possible to reach 98% of arsenic removal and 6.3 NTU of residual turbidity in clarified synthetic effluent.

  3. Mesoporous Silica: A Suitable Adsorbent for Amines

    Directory of Open Access Journals (Sweden)

    Abdollahzadeh-Ghom Sara

    2009-01-01

    Full Text Available Abstract Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices.

  4. Adsorbate Diffusion on Transition Metal Nanoparticles

    Science.gov (United States)

    2015-01-01

    systematically studied adsorption and diffusion of atomic and diatomic species (H, C, N, O, CO, and NO) on nanometer-sized Pt and Cu nanoparticles with...species and two diatomic molecules (H, C, N, O, CO, and NO) as adsorbates and study the adsorption and diffusion of these adsorbates across the edges...DOE-BES, Division of Chemical Sciences (grant DE-FG02-05ER15731), and by the Air Force Office of Scientific Research under a Basic Research Initiative

  5. TOPICAL REVIEW Textured silicon nitride: processing and anisotropic properties

    Directory of Open Access Journals (Sweden)

    Xinwen Zhu and Yoshio Sakka

    2008-01-01

    Full Text Available Textured silicon nitride (Si3N4 has been intensively studied over the past 15 years because of its use for achieving its superthermal and mechanical properties. In this review we present the fundamental aspects of the processing and anisotropic properties of textured Si3N4, with emphasis on the anisotropic and abnormal grain growth of β-Si3N4, texture structure and texture analysis, processing methods and anisotropic properties. On the basis of the texturing mechanisms, the processing methods described in this article have been classified into two types: hot-working (HW and templated grain growth (TGG. The HW method includes the hot-pressing, hot-forging and sinter-forging techniques, and the TGG method includes the cold-pressing, extrusion, tape-casting and strong magnetic field alignment techniques for β-Si3N4 seed crystals. Each processing technique is thoroughly discussed in terms of theoretical models and experimental data, including the texturing mechanisms and the factors affecting texture development. Also, methods of synthesizing the rodlike β-Si3N4 single crystals are presented. Various anisotropic properties of textured Si3 N4 and their origins are thoroughly described and discussed, such as hardness, elastic modulus, bending strength, fracture toughness, fracture energy, creep behavior, tribological and wear behavior, erosion behavior, contact damage behavior and thermal conductivity. Models are analyzed to determine the thermal anisotropy by considering the intrinsic thermal anisotropy, degree of orientation and various microstructure factors. Textured porous Si3N4 with a unique microstructure composed of oriented elongated β-Si3N4 and anisotropic pores is also described for the first time, with emphasis on its unique mechanical and thermal-mechanical properties. Moreover, as an important related material, textured α-Sialon is also reviewed, because the presence of elongated α-Sialon grains allows the production of textured

  6. Infrared Analysis Of Enzymes Adsorbed Onto Model Surfaces

    Science.gov (United States)

    Story, Gloria M.; Rauch, Deborah S.; Brode, Philip F.; Marcott, Curtis A.

    1989-12-01

    The adsorption of the enzymes, subtilisin BPN' and lysozyme, onto model surfaces was examined using attenuated total reflectance (ATR) infrared (IR) spectroscopy. Using a cylindrical internal reflection (CIRcle) cell with a Germanium (Ge) internal reflection element (IRE), model hydrophilic surfaces were made by plasma cleaning the IRE and model hydrophobic surfaces were made by precoating the IRE with a thin film of polystyrene. Gas chromatography (GC)-IR data collection software was used to monitor adsorption kinetics during the first five minutes after injection of the enzyme into the CIRcle cell. It was found that for both lysozyme and BPN', most of the enzyme that was going to adsorb onto the model surface did so within ten seconds after injection. Nearly an order-of-magnitude more BPN' adsorbed on the hydrophobic Ge surface than the hydrophilic one, while lysozyme adsorbed somewhat more strongly to the hydrophilic Ge surface. Overnight, the lysozyme layer continued to increase in thickness, while BPN' maintained its initial coverage. The appearance of carboxylate bands in some of the adsorbed BPN' spectra suggests the occurrence of peptide bond hydrolysis. A Au/Pd coating on the CIRcle cell o-rings had a significant effect on the adsorption of BPN'. (This coating was applied in an attempt to eliminate interfering Teflon absorption bands.) An apparent electrochemical reaction occurred, involving BPN', Ge, Au/Pd, and the salt solution used to stabilize BPN'. The result of this reaction was enhanced adsorption of the enzyme around the coated o-rings, etching of the Ge IRE at the o-ring site, and some autolysis of the enzyme. No such reaction was observed with lysozyme.

  7. Modeling and experimental investigations of Lamb waves focusing in anisotropic plates

    Energy Technology Data Exchange (ETDEWEB)

    Chapuis, Bastien [Departement Materiaux et Structures Composites, ONERA, 29 avenue de la Division Leclerc, 92322 Chatillon Cedex (France); Terrien, Nicolas [CETIM, 74 route de la Joneliere, 44326 Nantes Cedex 3 (France); Royer, Daniel, E-mail: Bastien.Chapuis@onera.fr [Laboratoire Ondes et Acoustique, ESPCI, Universite Paris 7, CNRS UMR 7587, 10 rue Vauquelin, 75231 Paris Cedex 05 (France)

    2011-01-01

    The phenomenon of Lamb waves focusing in anisotropic plates is theoretically and experimentally investigated. An analysis based on a far field approximation of the Green's function shows that Lamb waves focusing is analog to the phonon focusing effect. In highly anisotropic structures like composite plates the focusing of A{sub 0} and S{sub 0} mode is strong; the energy propagates preferentially in the fibre directions, which are minima of the slowness. This has to be taken into account when developing, for example, a transducer array for structural health monitoring systems based on Lamb waves in order to avoid dead zones.

  8. Anisotropic adsorption of oleate on diaspore and kaolinite crystals: Implications for their flotation separation

    Science.gov (United States)

    Xu, Longhua; Hu, Yuehua; Dong, Faqin; Gao, Zhiyong; Wu, Houqin; Wang, Zhen

    2014-12-01

    Comparative studies of flotation of oleate on diaspore and kaolinite in different particle size fractions (0.075-0.038 mm, 0.038-0.01 mm, 0-0.01 mm) are presented to investigate the influences of particle size. The flotation results show that the kaolinite recovery increases with a decrease in particle size, while the case of diaspore is the opposite. Chemisorptions of anionic oleate collector on the surface Al sites of the negatively charged diaspore and kaolinite are confirmed by zeta potential and FTIR measurements. Anisotropic surface broken bond densities are calculated based on surface crystal chemistry to characterize anisotropic wettability of mineral crystals. The increasing order of broken bond densities (Db) and hydrophobicity for different crystal planes of diaspore and kaolinite correlate well with increasing the number of broken Alsbnd O bonds. The anisotropic adsorption of oleate on different crystal planes of diaspore and kaolinite are studied in terms of interaction energies computed by molecular dynamics (MD) simulations. The oleate is adsorbed more readily on (0 1 0) than (0 0 1) for diaspore. As for kaolinite, the oleate adsorption is considerably less on (0 0 1) as compared to (1 10). The conclusions drawn from purely theoretical computations are in good agreement with our experimental contact angle results.

  9. Resonances of the helium atom in a strong magnetic field

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Al-Hujaj, Omar-Alexander; Schmelcher, Peter

    2007-01-01

    We present an investigation of the resonances of a doubly excited helium atom in a strong magnetic field covering the regime B=0–100  a.u. A full-interaction approach which is based on an anisotropic Gaussian basis set of one-particle functions being nonlinearly optimized for each field strength...

  10. Design and development of anisotropic inorganic/polystyrene nanocomposites by surface modification of zinc oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xiao [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Research Center for Translational Medicine, East Hospital, the Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200092 (China); Huang, Shiming [Department of Physics, Tongji University, Shanghai 200092 (China); Wang, Yilong, E-mail: yilongwang@tongji.edu.cn [Research Center for Translational Medicine, East Hospital, the Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200092 (China); Shi, Donglu, E-mail: shid@ucmail.uc.edu [Research Center for Translational Medicine, East Hospital, the Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200092 (China); The Materials Science and Engineering Program, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221 (United States)

    2016-07-01

    Anisotropic yolk/shell or Janus inorganic/polystyrene nanocomposites were prepared by combining miniemulsion polymerization and sol–gel reaction. The morphologies of the anisotropic composites were found to be greatly influenced by surface modification of zinc oxide (ZnO) nanoparticle seeds. Two different types of the oleic acid modified ZnO nanoparticles (OA-ZnO) were prepared by post-treatment of commercial ZnO powder and homemade OA-ZnO nanoparticles. The morphologies and properties of the nanocomposites were investigated by transmission electron microscope (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and energy dispersive X-ray spectroscopy (EDX). It was found that both post-treated OA-ZnO and in-situ prepared OA-ZnO nanoparticles resulted in the yolk–shell and Janus structure nanocomposites, but with varied size and morphology. These nanocomposites showed stable and strong fluorescence by introducing quantum dots as the co-seeds. The fluorescent anisotropic nanocomposites were decorated separately with surface carboxyl and hydroxyl groups. These composites with unique anisotropic properties will have high potential in biomedical applications, particularly in bio-detection. - Graphical abstract: Design and development of anisotropic inorganic/polystyrene nanocomposites by surface modification of zinc oxide nanoparticles. - Highlights: • Non-magnetic anisotropic yolk/shell or Janus nanocomposites are prepared and characterized. • Different surface modification of zinc oxide (ZnO) nanoparticles results in varied morphology and size of the final product. • Fluorescent anisotropic nanocomposites embodying quantum dots are an ideal candidate for bio-detection applications.

  11. PURCELL EFFECT IN EXTREMELY ANISOTROPIC ELLIPTIC METAMATERIALS

    Directory of Open Access Journals (Sweden)

    Alexander V. Chebykin

    2014-11-01

    Full Text Available The paper deals with theoretical demonstration of Purcell effect in extremely anisotropic metamaterials with elliptical isofrequency surface. This effect is free from association with divergence in density of states unlike the case of hyperbolic metamaterials. It is shown that a large Purcell factor can be observed without excitation of modes with large wave vectors in one direction, and the component of the wave vector normal to the layers is less than k0. For these materials the possibility is given for increasing of the power radiated in the medium, as well as the power radiated from material into free space across the medium border situated transversely to the layers. We have investigated isofrequency contours and the dependence of Purcell factor from the frequency for infinite layered metamaterial structure. In the visible light range strong spatial dispersion gives no possibility to obtain enhancement of spontaneous emission in metamaterial with unit cell which consists of two layers. This effect can be achieved in periodic metal-dielectric layered nanostructures with a unit cell containing two different metallic layers and two dielectric ones. Analysis of the dependences for Purcell factor from the frequency shows that the spontaneous emission is enhanced by a factor of ten or more only for dipole orientation along metamaterial layers, but in the case of the transverse orientation radiation can be enhanced only 2-3 times at most. The results can be used to create a new type of metamaterials with elliptical isofrequency contours, providing a more efficient light emission in the far field.

  12. On spectral scaling laws for incompressible anisotropic magnetohydrodynamic turbulence

    International Nuclear Information System (INIS)

    Galtier, Sebastien; Pouquet, Annick; Mangeney, Andre

    2005-01-01

    A heuristic model is given for anisotropic magnetohydrodynamics turbulence in the presence of a uniform external magnetic field B 0 e parallel . The model is valid for both moderate and strong B 0 and is able to describe both the strong and weak wave turbulence regimes as well as the transition between them. The main ingredient of the model is the assumption of constant ratio at all scales between the linear wave period and the nonlinear turnover time scale. Contrary to the model of critical balance introduced by Goldreich and Sridhar [Astrophys. J. 438, 763 (1995)], it is not assumed, in addition, that this ratio be equal to unity at all scales. This allows us to make use of the Iroshnikov-Kraichnan phenomenology; it is then possible to recover the widely observed anisotropic scaling law k parallel ∝k perpendicular 2/3 between parallel and perpendicular wave numbers (with reference to B 0 e parallel and to obtain for the total-energy spectrum E(k perpendicular ,k parallel )∼k perpendicular -α k parallel -β the universal prediction, 3α+2β=7. In particular, with such a prediction, the weak Alfven wave turbulence constant-flux solution is recovered and, for the first time, a possible explanation to its precursor found numerically by Galtier et al. [J. Plasma Phys. 63, 447 (2000)] is given.

  13. Insertion of anisotropic particles in lamellar surfactant phases

    International Nuclear Information System (INIS)

    Grillo, Isabelle

    1998-01-01

    We search for the interactions governing the possibility to mix organic and inorganic colloids. We use laponite, a synthetic anionic clay, made of 30 nm diameter and 1 nm thickness anisotropic disks. Three surfactant Systems, an anionic one (AOT), a cationic one (DDAB) and a nonionic one (C 12 E 5 ) investigate three different cases of interaction forces. We establish experimentally the equilibrium phase diagrams and characterise the structure of these ternary Systems by SANS and SAXS experiments. We quantify the adsorption. An AOT bilayer surround the particle edges; an almost complete bilayer of DDAB and C 12 E 5 is formed on the basal faces. SANS contrast variation experiments under controlled conditions along the adsorption isotherm of C 12 E 5 allow to determine the average thickness of the adsorbed surfactant layer. In the monophasic lamellar domain, the particles stay between the membranes, when the spacing is larger than the particle thickness. In the biphasic domain, dense clay aggregates are in equilibrium with a lamellar phase, containing few amount of particles. They enter in the AOT bilayers when the space between the bilayers are smaller than 8 A. From the phase diagram and interaction forces study, three conditions of stability emerge: - an osmotic one: the osmotic lamellar pressure is higher or equal to the colloidal one. - an energetic one: the interaction energy between a particle and the surfactant bilayer is close to the particle energy in aqueous suspension. - an entropic one: particles should not inhibit the stabilising fluctuations of the lamellar phase. (author) [fr

  14. An iterative, fast-sweeping-based eikonal solver for 3D tilted anisotropic media

    KAUST Repository

    Waheed, Umair bin

    2015-03-30

    Computation of first-arrival traveltimes for quasi-P waves in the presence of anisotropy is important for high-end near-surface modeling, microseismic-source localization, and fractured-reservoir characterization - and it requires solving an anisotropic eikonal equation. Anisotropy deviating from elliptical anisotropy introduces higher order nonlinearity into the eikonal equation, which makes solving the eikonal equation a challenge. We addressed this challenge by iteratively solving a sequence of simpler tilted elliptically anisotropic eikonal equations. At each iteration, the source function was updated to capture the effects of the higher order nonlinear terms. We used Aitken\\'s extrapolation to speed up convergence rate of the iterative algorithm. The result is an algorithm for computing first-arrival traveltimes in tilted anisotropic media. We evaluated the applicability and usefulness of our method on tilted transversely isotropic media and tilted orthorhombic media. Our numerical tests determined that the proposed method matches the first arrivals obtained by wavefield extrapolation, even for strongly anisotropic and highly complex subsurface structures. Thus, for the cases where two-point ray tracing fails, our method can be a potential substitute for computing traveltimes. The approach presented here can be easily extended to compute first-arrival traveltimes for anisotropic media with lower symmetries, such as monoclinic or even the triclinic media.

  15. The finite-element method for multigroup neutron transport: anisotropic scattering in 1-D slab geometry

    International Nuclear Information System (INIS)

    Riyait, N.S.; Ackroyd, R.T.

    1987-01-01

    Proof-tests on 1-D multigroup neutron transport problems are reported for strong anisotropic scattering. These tests have been undertaken as part of the validation of the 3-D multigroup finite-element transport code FELTRAN for anisotropic scattering media. To illustrate the treatment of within-group and intergroup anisotropic scattering in the finite-element method the relevant theory is outlined. Ingroup scattering is checked using the backward-forward-isotropic (BFI) scattering law for source and eigenvalue problems. With this law anisotropic scattering problems can be transformed into equivalent isotropic scattering problems. In this way the well-validated isotropic scattering version of FELTRAN is used to validate the anisotropic version. Intergroup scattering effects are checked by solving few-group source problems for P 1 and P 3 scattering and the BFI scattering law. For P 1 and P 3 scattering checks are made with the discrete-ordinate finite-difference code ANISN and the spherical harmonics finite-difference code MARC/PN. For the BFI scattering law comparison is made with two-group exact solutions of Williams (1985) for 1-D systems. (author)

  16. Anisotropic structure beneath central Java from local earthquake tomography

    Science.gov (United States)

    Koulakov, Ivan; Jakovlev, Andrey; Luehr, Birger G.

    2009-02-01

    In this study we present the new tomographic code ANITA which provides 3-D anisotropic P and isotropic S velocity distribution based on P and S traveltimes from local seismicity. For the P anisotropic model, we determine four parameters for each parameterization cell. This represents an orthorhombic anisotropy with one predefined direction oriented vertically. Three of the parameters describe slowness variations along three horizontal orientations with azimuths of 0°, 60°, and 120°, and one is a perturbation along the vertical axis. The nonlinear iterative inversion procedure is similar to that used in the LOTOS code. We have implemented this algorithm for the updated data set of central Java, part of which was previously used for the isotropic inversion. It was obtained that the crustal and uppermost mantle velocity structure beneath central Java is strongly anisotropic with 7-10% of maximal difference between slow and fast velocity in different directions. In the forearc (area between southern coast and volcanoes), the structure of both isotropic and anisotropic structure is strongly heterogeneous. Variety of anisotropy orientations and highly contrasted velocity patterns can be explained by a complex block structure of the crust. Beneath volcanoes we observe faster velocities in vertical direction, which is probably an indicator for vertically oriented structures (channels, dykes). In the crust beneath the middle part of central Java, north to Merapi and Lawu volcanoes, we observe a large and very intense anomaly with a velocity decrease of up to 30% and 35% for P and S models, respectively. Inside this anomaly E-W orientation of fast velocity takes place, probably caused by regional extension stress regime. In a vertical section we observe faster horizontal velocities inside this anomaly that might be explained by layering of sediments and/or penetration of quasi-horizontal lenses with molten magma. In the mantle, trench parallel anisotropy is observed

  17. Anisotropic nanomaterials: structure, growth, assembly, and functions

    Science.gov (United States)

    Sajanlal, Panikkanvalappil R.; Sreeprasad, Theruvakkattil S.; Samal, Akshaya K.; Pradeep, Thalappil

    2011-01-01

    Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications. PMID:22110867

  18. Effective medium theory for anisotropic metamaterials

    KAUST Repository

    Zhang, Xiujuan

    2015-01-20

    Materials with anisotropic material parameters can be utilized to fabricate many fascinating devices, such as hyperlenses, metasolids, and one-way waveguides. In this study, we analyze the effects of geometric anisotropy on a two-dimensional metamaterial composed of a rectangular array of elliptic cylinders and derive an effective medium theory for such a metamaterial. We find that it is possible to obtain a closed-form analytical solution for the anisotropic effective medium parameters, provided the aspect ratio of the lattice and the eccentricity of the elliptic cylinder satisfy certain conditions. The derived effective medium theory not only recovers the well-known Maxwell-Garnett results in the quasi-static regime, but is also valid beyond the long-wavelength limit, where the wavelength in the host medium is comparable to the size of the lattice so that previous anisotropic effective medium theories fail. Such an advance greatly broadens the applicable realm of the effective medium theory and introduces many possibilities in the design of structures with desired anisotropic material characteristics. A real sample of a recently theoretically proposed anisotropic medium, with a near-zero index to control the flux, is achieved using the derived effective medium theory, and control of the electromagnetic waves in the sample is clearly demonstrated.

  19. The dynamics and structures of adsorbed surfaces

    International Nuclear Information System (INIS)

    Nielsen, M.; Ellenson, W.D.; McTague, J.P.

    1978-01-01

    This article reviews neutron scattering work performed on films of simple gas atoms and molecules adsorbed primarily on graphite surfaces. Exfoliated graphite substrates such as Grafoil were first used in this kind of measurements about five years ago and new results have been reported at an increasing pace. Elastic neutron diffraction measurements, determining the two-dimensional structural ordering of the adsorbed films, have been performed on layers of N 2 , Ar, H 2 , D 2 , O 2 , Kr, and He. Measurements on layers of larger molecules such as CD 4 and ND 3 have been reported very recently. Inelastic neutron scattering measurements, studying the dynamics of the adsorbed films are only possible in a few especially favourable cases such as 36 Ar and D 2 films, where the coherent phonon scattering cross-sections are very large. In other cases incoherent scattering from hydrogen can give information about e.g. the mobility of molecules such as NH 3 or the internal modes of adsorbed molecules such as C 4 H 10 . Neutron scattering measurements where substrates other than graphite products are used as the adsorbents will not be reviewed here. However, the power of the technique will be demonstrated in an example of H 2 physisorbed to activated alumina and in an example where hydrogen is chemisorbed to Raney nickel. (author)

  20. Method for modifying trigger level for adsorber regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, Michael J.; Cunningham, Michael J.

    2010-05-25

    A method for modifying a NO.sub.x adsorber regeneration triggering variable. Engine operating conditions are monitored until the regeneration triggering variable is met. The adsorber is regenerated and the adsorbtion efficiency of the adsorber is subsequently determined. The regeneration triggering variable is modified to correspond with the decline in adsorber efficiency. The adsorber efficiency may be determined using an empirically predetermined set of values or by using a pair of oxygen sensors to determine the oxygen response delay across the sensors.

  1. Adsorbent catalytic nanoparticles and methods of using the same

    Energy Technology Data Exchange (ETDEWEB)

    Slowing, Igor Ivan; Kandel, Kapil

    2017-01-31

    The present invention provides an adsorbent catalytic nanoparticle including a mesoporous silica nanoparticle having at least one adsorbent functional group bound thereto. The adsorbent catalytic nanoparticle also includes at least one catalytic material. In various embodiments, the present invention provides methods of using and making the adsorbent catalytic nanoparticles. In some examples, the adsorbent catalytic nanoparticles can be used to selectively remove fatty acids from feedstocks for biodiesel, and to hydrotreat the separated fatty acids.

  2. Head-wave coefficients in anisotropic media

    Science.gov (United States)

    Chapman, Chris

    2018-03-01

    Reflections and transmissions from interfaces can generate head waves. Although the kinematic properties of head waves are modelled simply using ray concepts, the dynamic properties require an extension of ray theory or the use of wave theory. Head waves are important in exploration and crustal seismology as they indicate the existence of an interface and the velocity of the generating wave. Head waves have been described in the literature for isotropic media but the extension to anisotropic media seems to be lacking. The expressions for the head-wave coefficients using ray concepts or wave theory differ, and their equality is not obvious. This paper extends the theory for head-wave coefficients to anisotropic media using both ray theory and wave theory, and generalizes the proof of equality of the two methods. Simple numerical examples confirm this equality and indicate how the head-wave results can be calculated in anisotropic media and included in a ray-tracing algorithm.

  3. Elastic properties of spherically anisotropic piezoelectric composites

    International Nuclear Information System (INIS)

    En-Bo, Wei; Guo-Qing, Gu; Ying-Ming, Poon

    2010-01-01

    Effective elastic properties of spherically anisotropic piezoelectric composites, whose spherically anisotropic piezoelectric inclusions are embedded in an infinite non-piezoelectric matrix, are theoretically investigated. Analytical solutions for the elastic displacements and the electric potentials under a uniform external strain are derived exactly. Taking into account of the coupling effects of elasticity, permittivity and piezoelectricity, the formula is derived for estimating the effective elastic properties based on the average field theory in the dilute limit. An elastic response mechanism is revealed, in which the effective elastic properties increase as inclusion piezoelectric properties increase and inclusion dielectric properties decrease. Moreover, a piezoelectric response mechanism, of which the effective piezoelectric response vanishes due to the symmetry of spherically anisotropic composite, is also disclosed. (condensed matter: structure, thermal and mechanical properties)

  4. Obtuse triangle suppression in anisotropic meshes

    KAUST Repository

    Sun, Feng

    2011-12-01

    Anisotropic triangle meshes are used for efficient approximation of surfaces and flow data in finite element analysis, and in these applications it is desirable to have as few obtuse triangles as possible to reduce the discretization error. We present a variational approach to suppressing obtuse triangles in anisotropic meshes. Specifically, we introduce a hexagonal Minkowski metric, which is sensitive to triangle orientation, to give a new formulation of the centroidal Voronoi tessellation (CVT) method. Furthermore, we prove several relevant properties of the CVT method with the newly introduced metric. Experiments show that our algorithm produces anisotropic meshes with much fewer obtuse triangles than using existing methods while maintaining mesh anisotropy. © 2011 Elsevier B.V. All rights reserved.

  5. Generalized Fractional Derivative Anisotropic Viscoelastic Characterization

    Directory of Open Access Journals (Sweden)

    Harry H. Hilton

    2012-01-01

    Full Text Available Isotropic linear and nonlinear fractional derivative constitutive relations are formulated and examined in terms of many parameter generalized Kelvin models and are analytically extended to cover general anisotropic homogeneous or non-homogeneous as well as functionally graded viscoelastic material behavior. Equivalent integral constitutive relations, which are computationally more powerful, are derived from fractional differential ones and the associated anisotropic temperature-moisture-degree-of-cure shift functions and reduced times are established. Approximate Fourier transform inversions for fractional derivative relations are formulated and their accuracy is evaluated. The efficacy of integer and fractional derivative constitutive relations is compared and the preferential use of either characterization in analyzing isotropic and anisotropic real materials must be examined on a case-by-case basis. Approximate protocols for curve fitting analytical fractional derivative results to experimental data are formulated and evaluated.

  6. Protein purification using magnetic adsorbent particles

    DEFF Research Database (Denmark)

    Franzreb, M; Siemann-Herzberg, M.; Hobley, Timothy John

    2006-01-01

    The application of functionalised magnetic adsorbent particles in combination with magnetic separation techniques has received considerable attention in recent years. The magnetically responsive nature of such adsorbent particles permits their selective manipulation and separation in the presence...... of other suspended solids. Thus, it becomes possible to magnetically separate selected target species directly out of crude biological process liquors (e.g. fermentation broths, cell disruptates, plasma, milk, whey and plant extracts) simply by binding them on magnetic adsorbents before application...... of a magnetic field. By using magnetic separation in this way, the several stages of sample pretreatment (especially centrifugation, filtration and membrane separation) that are normally necessary to condition an extract before its application on packed bed chromatography columns, may be eliminated. Magnetic...

  7. Boron removal from wastewater using adsorbents.

    Science.gov (United States)

    Kluczka, J; Trojanowska, J; Zolotajkin, M; Ciba, J; Turek, M; Dydo, P

    2007-01-01

    In the present study, boron adsorption on activated alumina and activated carbon impregnated with calcium chloride, tartaric acid and mannitol was investigated. The adsorbate in question was the wastewater from the chemical landfill in Tarnowskie Gory of 25-70 mg l(-1) boron content. The removal of boron from the above-described wastewater was examined in the static (batch) and dynamic (column) experiments. The static experiments were carried out to assess boron adsorption isotherms, based on which the most efficient adsorbent as well as the rough resin load was determined. On the basis of the dynamic experiment results, the boron adsorptive capacities of the examined resins were deduced. It was concluded that the use of the impregnants increased the ability of activated carbon to adsorb boron. Granulated activated carbon WG-12 impregnated with mannitol was found to be the most promising for the boron removal from wastewater of the Chemical Wastewater Plant in Tarnowskie Gory.

  8. Anisotropic nanomaterials preparation, properties, and applications

    CERN Document Server

    Li, Quan

    2015-01-01

    In this book anisotropic one-dimensional and two-dimensional nanoscale building blocks and their assembly into fascinating and qualitatively new functional structures embracing both hard and soft components are explained. Contributions from leading experts regarding important aspects like synthesis, assembly, properties and applications of the above materials are compiled into a reference book. The anisotropy, i.e. the direction-dependent physical properties, of materials is fascinating and elegant and has sparked the quest for anisotropic materials with useful properties. With such a curiosi

  9. Modelling of CMUTs with Anisotropic Plates

    DEFF Research Database (Denmark)

    la Cour, Mette Funding; Christiansen, Thomas Lehrmann; Jensen, Jørgen Arendt

    2012-01-01

    Traditionally, CMUTs are modelled using the isotropic plate equation and this leads to deviations between analytical calculations and FEM simulations. In this paper, the deflection profile and material parameters are calculated using the anisotropic plate equation. It is shown that the anisotropic...... calculations match perfectly with FEM while an isotropic approach causes up to 10% deviations in deflection profile. Furthermore, we show how commonly used analytic modelling methods such as static calculations of the pull-in voltage and dynamic modelling through an equivalent circuit representation can...

  10. Probing molecular adsorbates with core-level spectroscopies: Electronic structure and bonding models

    Science.gov (United States)

    Fohlisch, Alexander

    Resonantly excited X-ray emission spectroscopy has been applied to study the valence electronic structure of molecular adsorbates in an atom specific and orbital symmetry selective manner. In combination with ab initio cluster calculations, electronic structure and bonding models have been derived. Existing models of surface chemical bonding have been reviewed and partially revised. Most notably, the bonding mechanism of carbon monoxide (CO) on transition and noble metals has been revised and is found to be the result of a strong covalent interaction between the CO orbitals and the metal bands within each orbital symmetry. A characteristic allylic configuration is found in the π system and strong polarization within the σ system. The equilibrium properties of adsorbed CO are the direct result of a balance between the repulsive σ-interaction and the attractive π-interaction both in terms of the total energy and the local bond properties. The bonding of ammonia (NH3) on the Cu(110) surface is found to be dominated by a large covalent interaction, which contrasts the previous model of a strong electrostatic interaction. Furthermore, adsorbate-adsorbate interaction leads to a tilted adsorption geometry. Ethylene (C2H4) on Cu(110) is adsorbed in the di-σ configuration, according to the generally accepted Dewar Chatt Duncanson model for hydrocarbon adsorption. The application and interpretation of resonantly excited X-ray emission on these systems also required a thorough discussion of the spectroscopic process. Another topic was the vibrational fine structure in the X-ray photoemission core-level main lines of adsorbed molecules. The observation of the vibrational fine structure in molecular adsorbates is remarkable, as it was previously thought impossible to observe due to solid state broadening contributions. A detailed analysis of the vibrational fine structure and the line profile makes it possible to study the electronic and geometric properties of the core

  11. Theoretical Insight of Physical Adsorption for a Single Component Adsorbent + Adsorbate System: II. The Henry Region

    KAUST Repository

    Chakraborty, Anutosh

    2009-07-07

    The Henry coefficients of a single component adsorbent + adsorbate system are calculated from experimentally measured adsorption isotherm data, from which the heat of adsorption at zero coverage is evaluated. The first part of the papers relates to the development of thermodynamic property surfaces for a single-component adsorbent + adsorbate system1 (Chakraborty, A.; Saha, B. B.; Ng, K. C.; Koyama, S.; Srinivasan, K. Langmuir 2009, 25, 2204). A thermodynamic framework is presented to capture the relationship between the specific surface area (Ai) and the energy factor, and the surface structural and the surface energy heterogeneity distribution factors are analyzed. Using the outlined approach, the maximum possible amount of adsorbate uptake has been evaluated and compared with experimental data. It is found that the adsorbents with higher specific surface areas tend to possess lower heat of adsorption (ΔH°) at the Henry regime. In this paper, we have established the definitive relation between Ai and ΔH° for (i) carbonaceous materials, metal organic frameworks (MOFs), carbon nanotubes, zeolites + hydrogen, and (ii) activated carbons + methane systems. The proposed theoretical framework of At and AH0 provides valuable guides for researchers in developing advanced porous adsorbents for methane and hydrogen uptake. © 2009 American Chemical Society.

  12. An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets

    Science.gov (United States)

    Liu, Mingjie; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Takata, Masaki; Aida, Takuzo

    2015-01-01

    Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.

  13. Anisotropic toughness and strength in graphene and its atomistic origin

    Science.gov (United States)

    Hossain, M. Zubaer; Ahmed, Tousif; Silverman, Benjamin; Khawaja, M. Shehroz; Calderon, Justice; Rutten, Andrew; Tse, Stanley

    2018-01-01

    This paper presents the implication of crystallographic orientation on toughness and ideal strength in graphene under lattice symmetry-preserving and symmetry-breaking deformations. In symmetry-preserving deformation, both toughness and strength are isotropic, regardless of the chirality of the lattice; whereas, in symmetry-breaking deformation they are strongly anisotropic, even in the presence of vacancy defects. The maximum and minimum of toughness or strength occur for loading along the zigzag direction and the armchair direction, respectively. The anisotropic behavior is governed by a complex interplay among bond-stretching deformation, bond-bending deformation, and the chirality of the lattice. Nevertheless, the condition for crack-nucleation is dictated by the maximum bond-force required for bond rupture, and it is independent of the chiral angle of the lattice or loading direction. At the onset of crack-nucleation a localized nucleation zone is formed, wherein the bonds rupture locally satisfying the maximum bond-force criterion. The nucleation zone acts as the physical origin in triggering the fracture nucleation process, but its presence is undetectable from the macroscopic stress-strain data.

  14. Volatile organic compounds adsorption using different types of adsorbent

    Directory of Open Access Journals (Sweden)

    Pimanmes Chanayotha

    2014-09-01

    Full Text Available Adsorbents were synthesized from coconut shell, coal and coke by pyrolysis followed by chemical activation process. These synthesized materials were used as adsorbents in adsorption test to determine the amount of volatile organic compounds (VOCs namely, 2-Hydroxyethyl methacrylate (HEMA, Octamethylcyclotetrasiloxane and Alkanes standard solution (C8-C20. The adsorption capacities of both synthesized adsorbents and commercial grade adsorbents (Carbotrap™ B and Carbotrap™ C were also compared. It was found that adsorbent A402, which was produced from coconut shell, activated with 40% (wt. potassium hydroxide and at activating temperature of 800°C for 1 hr, could adsorb higher amount of both HEMA and Octamethylcyclotetrasiloxane than other synthesized adsorbents. The maximum adsorption capacity of adsorbent A402 in adsorbing HEMA and Octamethylcyclotetrasiloxane were 77.87% and 50.82% respectively. These adsorption capabilities were 79.73% and 70.07% of the adsorption capacity of the commercial adsorbent Carbotrap™ B respectively. All three types of the synthesized adsorbent (A402, C302, C402 showed the capability to adsorb alkanes standard solution through the range of C8-C20 . However, their adsorption capacities were high in a specific range of C10-C11. The result from the isotherm plot was indicated that surface adsorption of synthesized adsorbent was isotherm type I while the surface adsorption of commercial adsorbent was isotherm type III.

  15. A Variational Approach to Perturbed Discrete Anisotropic Equations

    Directory of Open Access Journals (Sweden)

    Amjad Salari

    2016-01-01

    Full Text Available We continue the study of discrete anisotropic equations and we will provide new multiplicity results of the solutions for a discrete anisotropic equation. We investigate the existence of infinitely many solutions for a perturbed discrete anisotropic boundary value problem. The approach is based on variational methods and critical point theory.

  16. The Effect of Anisotropic Scatter on Atmospheric Neutron Transport

    Science.gov (United States)

    2015-03-26

    THE EFFECT OF ANISOTROPIC SCATTER ON ATMOSPHERIC NEUTRON TRANSPORT THESIS MARCH 2015 Nicholas J...iii AFIT-ENP-MS-15-M-085 THE EFFECT OF ANISOTROPIC SCATTER ON ATMOSPHERIC NEUTRON TRANSPORT THESIS Presented to the...EFFECT OF ANISOTROPIC SCATTER ON ATMOSPHERIC NEUTRON TRANSPORT Nicholas J. McIntee, BSE Major, USA Committee Membership: Dr. Kirk A. Mathews

  17. The Structures of Self-Assembled Monolayer Films of Organosulfur Compounds Adsorbed on Gold Single Crystals: Electron Diffraction Studies.

    Science.gov (United States)

    1988-01-01

    AD-M193 125 THE STRUCTURES OF SELF-RSSENSLED MOMOLAYER FILMS OF 1/1 ORGANOSULFUR COMPOUND..(U) HRlYARD UNJY CAMBRIDGE MASS DEPT OF CHEMISTRY L STRONG...VV L- ___ THE STRUCTURES OF SELF-ASSEMBLED MONOLAYER FILMS OF ORGANOSULFUR COMPOUNDS ADSORBED ON GOLD SINGLE CRYSTALS: ELECTRON DIFFRACTION STUDIES...true sulfide phase. V V ’A. LA8700876 REVISED The Structures of Self-Assembled Monolayer Films of Organosulfur Compounds Adsorbed on Gold Single

  18. Magnetically supported zeolite adsorbents for effluent treatment

    International Nuclear Information System (INIS)

    Gaydardjiev, S.

    1998-01-01

    An attempt was made to remove heavy metal ions from metallurgical effluents by means of magnetically supported fluidized bed column employing zeolite-magnetite complexes as adsorbents. The natural sorptive properties of acid modified clinoptilolite were used instead of synthetic beads. X-ray diffraction and DTA studies on the raw material confirmed that the main zeolite mineral was clinoptilolite. (author)

  19. Development and characterization of hydrocarbon adsorbent from ...

    African Journals Online (AJOL)

    Raw materials obtained from a local market were used for the production of potential adsorbent. The materials were subjected to preliminary carbonization in a furnace at a controlled temperature in an inert atmosphere and chemical activation was carried out on the carbonized sample. Nylon and used tyre were ...

  20. Hypersurface-homogeneous cosmological models with anisotropic ...

    Indian Academy of Sciences (India)

    2016-12-05

    Dec 5, 2016 ... DOI 10.1007/s12043-016-1317-4. Hypersurface-homogeneous cosmological models with anisotropic dark energy in Saez–Ballester theory of gravitation. M K VERMA1, S CHANDEL2 and SHRI RAM2,∗. 1Department of Mathematics, Baba Banarasi Das National Institute of Technology & Management,.

  1. Anisotropic Hanle line shape via magnetothermoelectric phenomena

    NARCIS (Netherlands)

    Das, Kumar; Dejene, Fasil; van Wees, Bart; Vera Marun, Ivan

    2016-01-01

    We observe anisotropic Hanle line shape with unequal in-plane and out-of-plane nonlocal signals for spin precession measurements carried out on lateral metallic spin valves with transparent interfaces. The conventional interpretation for this anisotropy corresponds to unequal spin relaxation times

  2. Adaptive slices for acquisition of anisotropic BRDF

    Czech Academy of Sciences Publication Activity Database

    Vávra, Radomír; Filip, Jiří

    (2018) ISSN 2096-0433 R&D Projects: GA ČR GA17-18407S Institutional support: RVO:67985556 Keywords : anisotropic BRDF * slice * sampling Subject RIV: BD - Theory of Information http://library.utia.cas.cz/separaty/2018/RO/vavra-0486116.pdf

  3. Theory of anisotropic diamagnetism, local moment magnetization ...

    Indian Academy of Sciences (India)

    Theory of anisotropic diamagnetism, local moment magnetization and carrier spin-polarization in Pb1-EuTe ... Gopalpur 761 002, India; Department of Physics, Jagannath Institute for Technology and Management, Parlakhemundi 761 211, India; Department of Physics, Berhampur University, Berhampur 760 007, India ...

  4. Hypersurface-homogeneous cosmological models with anisotropic ...

    Indian Academy of Sciences (India)

    The present study deals with hypersurface-homogeneous cosmological models with anisotropic dark energy in Saez–Ballester theory of gravitation. Exact solutions of field equations are obtained by applying a special law of variation of Hubble's parameter that yields a constant negative value of the deceleration parameter.

  5. Minimally coupled scalar field cosmology in anisotropic ...

    Indian Academy of Sciences (India)

    We study a spatially homogeneous and anisotropic cosmological model in the Einstein gravitational theory with a minimally coupled scalar field. We consider a non-interacting combination of scalar field and perfect fluid as the source of matter components which are separately conserved. The dynamics of cosmic scalar ...

  6. Algebraic solution of an anisotropic nonquadratic potential

    International Nuclear Information System (INIS)

    Boschi Filho, H.; Vaidya, A.N.

    1990-06-01

    We show that an anisotropic nonquadratic potential, for which a path integral treatment had been recently discussed in the literature, possesses the (SO(2,1)xSO(2,1))ΛSO(2,1) dynamical symmetry and constructs its Green function algebraically. A particular case which generates new eigenvalues and eigenfunctions is also discussed. (author). 11 refs

  7. Modelling anisotropic water transport in polymer composite

    Indian Academy of Sciences (India)

    This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation models were ...

  8. A new algorithm for anisotropic solutions

    Indian Academy of Sciences (India)

    We establish a new algorithm that generates a new solution to the Einstein field equations, with an anisotropic matter distribution, from a seed isotropic solution. The new solution is expressed in terms of integrals of an isotropic gravitational potential; and the integration can be completed exactly for particular isotropic seed ...

  9. Acoustic reflection from the boundary of anisotropic ...

    Indian Academy of Sciences (India)

    Vertical slownesses of waves at a boundary of an anisotropic thermoviscoelastic medium are calculated as roots of a polynomial equation of degree eight. Out of the corresponding eight waves, the four, which travel towards the boundary are identified as upgoing waves. Remaining four waves travel away from the boundary ...

  10. Ray tracing in anisotropic media with singularities

    Czech Academy of Sciences Publication Activity Database

    Vavryčuk, Václav

    2001-01-01

    Roč. 145, č. 1 (2001), s. 265-276 ISSN 0956-540X R&D Projects: GA ČR GA205/00/1350 Institutional research plan: CEZ:AV0Z3012916 Keywords : anisotropic media * ray tracing * singularities Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.366, year: 2001

  11. Minimally coupled scalar field cosmology in anisotropic ...

    Indian Academy of Sciences (India)

    2017-01-03

    Jan 3, 2017 ... a phantom field [24,25], quintom [26,27], k-essence. [28], tachyon [29] and so forth. It is well known that the evolution of the Uni- verse admits a scenario of anisotropic expansion and gains a lot of interest, under the light of the recently announced Planck Probe results [7]. The Bianchi models, which describe ...

  12. Modelling anisotropic water transport in polymer composite ...

    Indian Academy of Sciences (India)

    Abstract. This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation ...

  13. The method of images for anisotropic media

    International Nuclear Information System (INIS)

    Iosilevskii, Ya.A.

    1978-01-01

    The method of images is suggested to construct a scalar macroscopic field (dynamic or static) of a point source in an anisotropic half-space or flat slab. The field is found for an arbitrary orientation of the boundaries with respect to the crystallographic axes. (Auth.)

  14. Template-free and filamentary growth of silver nanowires: application to anisotropic conductive transparent flexible electrodes

    Science.gov (United States)

    Park, Sun Hwa; Shin, Ho Sun; Kim, Young Heon; Park, Hyun Min; Song, Jae Yong

    2013-02-01

    Silver nanowires (NWs) are currently fabricated via template-free or template-assisted methods. The former is based on a medium-mediated anisotropic synthesis, which enables precursor atoms to be selectively adsorbed onto specific crystallographic planes, and the latter is performed via directional growth guided by preformed templates. These methods are costly and complicated. We outline a facile and low-cost approach for the electrochemical synthesis of silver NWs in a manner that is template- and surfactant-free and that provides control over the NW diameter in the range of 80 to 800 nm by the repetition of nucleation and dissolution. The nanowires vertically grow with the help of the interface anisotropy driven by a field enhancement at the tips of the islands nucleated on the substrate in ultra-dilute electrolytes (ca. 10-5 M), which is similar to a lightning-rod effect. The silver nanowires of vertical configuration are utilized for fabrication of anisotropic conducting, transparent, and flexible films.Silver nanowires (NWs) are currently fabricated via template-free or template-assisted methods. The former is based on a medium-mediated anisotropic synthesis, which enables precursor atoms to be selectively adsorbed onto specific crystallographic planes, and the latter is performed via directional growth guided by preformed templates. These methods are costly and complicated. We outline a facile and low-cost approach for the electrochemical synthesis of silver NWs in a manner that is template- and surfactant-free and that provides control over the NW diameter in the range of 80 to 800 nm by the repetition of nucleation and dissolution. The nanowires vertically grow with the help of the interface anisotropy driven by a field enhancement at the tips of the islands nucleated on the substrate in ultra-dilute electrolytes (ca. 10-5 M), which is similar to a lightning-rod effect. The silver nanowires of vertical configuration are utilized for fabrication of

  15. The adsorber loop concept for the contact between seawater and adsorber granulate

    International Nuclear Information System (INIS)

    Koske, P.H.; Ohlrogge, K.

    1984-01-01

    The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the depleted water before this is leaving the adsorption unit. This concept enables high seawater velocities thus reducing the required bed area. Theoretical considerations are presented together with experimental results from field tests. (orig.) [de

  16. Radiolytic stability of gibbsite and boehmite with adsorbed water

    Science.gov (United States)

    Huestis, Patricia; Pearce, Carolyn I.; Zhang, X.; N'Diaye, Alpha T.; Rosso, Kevin M.; LaVerne, Jay A.

    2018-04-01

    Aluminum oxyhydroxide (boehmite, AlOOH) and aluminum hydroxide (gibbsite, Al(OH)3) powders with adsorbed water were irradiated with γ-rays and 5 MeV He ions (α-particles) in order to determine overall radiation stability and chemical modification to the surface. No variation in overall phase or crystallinity due to radiolysis was observed with X-ray diffraction (XRD) and Raman spectroscopy for doses up to 2 MGy with γ-rays and 175 MGy with α-particles. Temperature programed desorption (TPD) of the water from the surface to the gas phase indicated that the water was chemisorbed and strongly bound. Water adsorption sites are of similar energy for both gibbsite and boehmite. Observation of the water adsorbed on the surface of gibbsite and boehmite with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) showed broad peaks at 3100-3600 cm-1 due to OH stretching that slowly decreased on heating to 500 °C, which corresponds well with the water vapor evolution observed with TPD. Both materials were found to be amorphous following heating to 500 °C. X-ray photoelectron spectroscopy (XPS) indicated surface reduction of Al(III) to Al metal on radiolysis with α-particles. Complete loss of chemisorbed water and the formation of bulk O atoms was observed following radiolysis with α-particles.

  17. Radiolytic stability of gibbsite and boehmite with adsorbed water

    Energy Technology Data Exchange (ETDEWEB)

    Huestis, Patricia; Pearce, Carolyn I.; Zhang, X.; N' Diaye, Alpha T.; Rosso, Kevin M.; LaVerne, Jay A.

    2018-04-01

    Aluminum oxyhydroxide (boehmite, AlOOH) and aluminum hydroxide (gibbsite, Al(OH)3) powders with adsorbed water were irradiated with -rays and 5 MeV He ions (α-particles) in order to determine overall radiation stability and chemical modification to the surface. No variation in overall phase or crystallinity due to radiolysis was observed with X-ray diffraction (XRD) and Raman spectroscopy for doses up to 2 MGy with -rays and 175 MGy with α-particles. Temperature programed desorption (TPD) of the water from the surface to the gas phase indicated that the water was chemisorbed and strongly bound. Water adsorption sites are of similar energy for both gibbsite and boehmite. Observation of the water adsorbed on the surface of gibbsite and boehmite with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) showed broad peaks at 3100-3600 cm-1 due to OH stretching that slowly decreased on heating to 500oC, which corresponds well with the water vapor evolution observed with TPD. Both materials were found to be amorphous following heating to 500oC. X-ray photoelectron spectroscopy (XPS) indicated surface reduction of Al(III) to Al metal on radiolysis with α-particles. Complete loss of chemisorbed water and the formation of bulk O atoms was observed following radiolysis with α-particles.

  18. Polymer Nanocomposites Containing Anisotropic Metal Nanostructures as Internal Strain Indicators

    Directory of Open Access Journals (Sweden)

    Giacomo Ruggeri

    2010-02-01

    Full Text Available Polymer/metal nanocomposite containing intrinsically anisotropic metal nanostructures such as metal nanorods and nanowires appeared extremely more sensitive and responsive to mechanical stimuli than nanocomposites containing spherical nanoparticles. After uniaxial stretching of the supporting polymer matrix (poly(vinyl alcohol, the elongated silver nanostructures embedded at low concentration into the polymer matrix (<1 wt % of Ag assume the direction of the drawing, yielding materials with a strong dichroic response of the absorption behavior. Accordingly, the film changed its color when observed under linearly polarized light already at moderate drawings. The results obtained suggest that nanocomposite films have potential in applications such as color polarizing filters, radiation responsive polymeric objects and smart flexible films in packaging applications.

  19. Views on the Anisotropic Nature of Ilva Valley Region

    Directory of Open Access Journals (Sweden)

    GABRIELA-ALINA MUREŞAN

    2012-01-01

    Full Text Available There are two concepts important for the authors of this article: anisotropic region and anisotropic space. Anisotropic region is defined by A. Dauphiné, the geographer (-mathematician, as a territorial unit whose structure results from the organisation of space along one or more axes. From the point of view of a territorial system, this type of region has some characteristics which differentiate it both from the homogeneous region and from the polarised one. These specificities have been analysed for Ilva Valley. The region of Ilva Valley is formed along the morphological axis represented by the Ilva River. The aim is to identify these specificities or their absence within this region. In this way we can determine whether this region is an anisotropic one or just an anisotropic space, namely whether it can be considered as evolving towards an anisotropic region, not yet complying with all characteristics of anisotropic regions.

  20. Method for removing strongly adsorbed surfactants and capping agents from metal to facilitate their catalytic applications

    Science.gov (United States)

    Adzic, Radoslav R.; Gong, Kuanping; Cai, Yun; Wong, Stanislaus; Koenigsmann, Christopher

    2016-11-08

    A method of synthesizing activated electrocatalyst, preferably having a morphology of a nanostructure, is disclosed. The method includes safely and efficiently removing surfactants and capping agents from the surface of the metal structures. With regard to metal nanoparticles, the method includes synthesis of nanoparticle(s) in polar or non-polar solution with surfactants or capping agents and subsequent activation by CO-adsorption-induced surfactant/capping agent desorption and electrochemical oxidation. The method produces activated macroparticle or nanoparticle electrocatalysts without damaging the surface of the electrocatalyst that includes breaking, increasing particle thickness or increasing the number of low coordination sites.

  1. Zeolites as alcohol adsorbents from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Cekova Blagica

    2006-01-01

    Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

  2. Analysis of Adsorbed Natural Gas Tank Technology

    Science.gov (United States)

    Knight, Ernest; Schultz, Conrad; Rash, Tyler; Dohnke, Elmar; Stalla, David; Gillespie, Andrew; Sweany, Mark; Seydel, Florian; Pfeifer, Peter

    With gasoline being an ever decreasing finite resource and with the desire to reduce humanity's carbon footprint, there has been an increasing focus on innovation of alternative fuel sources. Natural gas burns cleaner, is more abundant, and conforms to modern engines. However, storing compressed natural gas (CNG) requires large, heavy gas cylinders, which limits space and fuel efficiency. Adsorbed natural gas (ANG) technology allows for much greater fuel storage capacity and the ability to store the gas at a much lower pressure. Thus, ANG tanks are much more flexible in terms of their size, shape, and weight. Our ANG tank employs monolithic nanoporous activated carbon as its adsorbent material. Several different configurations of this Flat Panel Tank Assembly (FPTA) along with a Fuel Extraction System (FES) were examined to compare with the mass flow rate demands of an engine.

  3. Computer simulations of adsorbed liquid crystal films

    Science.gov (United States)

    Wall, Greg D.; Cleaver, Douglas J.

    2003-01-01

    The structures adopted by adsorbed thin films of Gay-Berne particles in the presence of a coexisting vapour phase are investigated by molecular dynamics simulation. The films are adsorbed at a flat substrate which favours planar anchoring, whereas the nematic-vapour interface favours normal alignment. On cooling, a system with a high molecule-substrate interaction strength exhibits substrate-induced planar orientational ordering and considerable stratification is observed in the density profiles. In contrast, a system with weak molecule-substrate coupling adopts a director orientation orthogonal to the substrate plane, owing to the increased influence of the nematic-vapour interface. There are significant differences between the structures adopted at the two interfaces, in contrast with the predictions of density functional treatments of such systems.

  4. Optical transmission properties of an anisotropic defect cavity in one-dimensional photonic crystal

    Science.gov (United States)

    Ouchani, Noama; El Moussaouy, Abdelaziz; Aynaou, Hassan; El Hassouani, Youssef; El Boudouti, El Houssaine; Djafari-Rouhani, Bahram

    2018-01-01

    We investigate theoretically the possibility to control the optical transmission in the visible and infrared regions by a defective one dimensional photonic crystal formed by a combination of a finite isotropic superlattice and an anisotropic defect layer. The Green's function approach has been used to derive the reflection and the transmission coefficients, as well as the densities of states of the optical modes. We evaluate the delay times of the localized modes and we compare their behavior with the total densities of states. We show that the birefringence of an anisotropic defect layer has a significant impact on the behavior of the optical modes in the electromagnetic forbidden bands of the structure. The amplitudes of the defect modes in the transmission and the delay time spectrum, depend strongly on the position of the cavity layer within the photonic crystal. The anisotropic defect layer induces transmission zeros in one of the two components of the transmission as a consequence of a destructive interference of the two polarized waves within this layer, giving rise to negative delay times for some wavelengths in the visible and infrared light ranges. This property is a typical characteristic of the anisotropic photonic layer and is without analogue in their counterpart isotropic defect layers. This structure offers several possibilities for controlling the frequencies, transmitted intensities and the delay times of the optical modes in the visible and infrared regions. It can be a good candidate for realizing high-precision optical filters.

  5. Green Adsorbents for Wastewaters: A Critical Review

    Science.gov (United States)

    Kyzas, George Z.; Kostoglou, Margaritis

    2014-01-01

    One of the most serious environmental problems is the existence of hazardous and toxic pollutants in industrial wastewaters. The major hindrance is the simultaneous existence of many/different types of pollutants as (i) dyes; (ii) heavy metals; (iii) phenols; (iv) pesticides and (v) pharmaceuticals. Adsorption is considered to be one of the most promising techniques for wastewater treatment over the last decades. The economic crisis of the 2000s led researchers to turn their interest in adsorbent materials with lower cost. In this review article, a new term will be introduced, which is called “green adsorption”. Under this term, it is meant the low-cost materials originated from: (i) agricultural sources and by-products (fruits, vegetables, foods); (ii) agricultural residues and wastes; (iii) low-cost sources from which most complex adsorbents will be produced (i.e., activated carbons after pyrolysis of agricultural sources). These “green adsorbents” are expected to be inferior (regarding their adsorption capacity) to the super-adsorbents of previous literature (complex materials as modified chitosans, activated carbons, structurally-complex inorganic composite materials etc.), but their cost-potential makes them competitive. This review is a critical approach to green adsorption, discussing many different (maybe in some occasions doubtful) topics such as: (i) adsorption capacity; (ii) kinetic modeling (given the ultimate target to scale up the batch experimental data to fixed-bed column calculations for designing/optimizing commercial processes) and (iii) critical techno-economical data of green adsorption processes in order to scale-up experiments (from lab to industry) with economic analysis and perspectives of the use of green adsorbents. PMID:28788460

  6. Green Adsorbents for Wastewaters: A Critical Review

    Directory of Open Access Journals (Sweden)

    George Z. Kyzas

    2014-01-01

    Full Text Available One of the most serious environmental problems is the existence of hazardous and toxic pollutants in industrial wastewaters. The major hindrance is the simultaneous existence of many/different types of pollutants as (i dyes; (ii heavy metals; (iii phenols; (iv pesticides and (v pharmaceuticals. Adsorption is considered to be one of the most promising techniques for wastewater treatment over the last decades. The economic crisis of the 2000s led researchers to turn their interest in adsorbent materials with lower cost. In this review article, a new term will be introduced, which is called “green adsorption”. Under this term, it is meant the low-cost materials originated from: (i agricultural sources and by-products (fruits, vegetables, foods; (ii agricultural residues and wastes; (iii low-cost sources from which most complex adsorbents will be produced (i.e., activated carbons after pyrolysis of agricultural sources. These “green adsorbents” are expected to be inferior (regarding their adsorption capacity to the super-adsorbents of previous literature (complex materials as modified chitosans, activated carbons, structurally-complex inorganic composite materials etc., but their cost-potential makes them competitive. This review is a critical approach to green adsorption, discussing many different (maybe in some occasions doubtful topics such as: (i adsorption capacity; (ii kinetic modeling (given the ultimate target to scale up the batch experimental data to fixed-bed column calculations for designing/optimizing commercial processes and (iii critical techno-economical data of green adsorption processes in order to scale-up experiments (from lab to industry with economic analysis and perspectives of the use of green adsorbents.

  7. Cosmological signatures of anisotropic spatial curvature

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Thiago S. [Departamento de Física, Universidade Estadual de Londrina, 86057-970, Londrina – PR (Brazil); Marugán, Guillermo A. Mena [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006, Madrid (Spain); Carneiro, Saulo, E-mail: tspereira@uel.br, E-mail: mena@iem.cfmac.csic.es, E-mail: saulo.carneiro@pq.cnpq.br [Instituto de Física, Universidade Federal da Bahia, 40210-340, Salvador – BA (Brazil)

    2015-07-01

    If one is willing to give up the cherished hypothesis of spatial isotropy, many interesting cosmological models can be developed beyond the simple anisotropically expanding scenarios. One interesting possibility is presented by shear-free models in which the anisotropy emerges at the level of the curvature of the homogeneous spatial sections, whereas the expansion is dictated by a single scale factor. We show that such models represent viable alternatives to describe the large-scale structure of the inflationary universe, leading to a kinematically equivalent Sachs-Wolfe effect. Through the definition of a complete set of spatial eigenfunctions we compute the two-point correlation function of scalar perturbations in these models. In addition, we show how such scenarios would modify the spectrum of the CMB assuming that the observations take place in a small patch of a universe with anisotropic curvature.

  8. Equilibrium-Based Nonhomogeneous Anisotropic Beam Element

    DEFF Research Database (Denmark)

    Krenk, Steen; Couturier, Philippe

    2017-01-01

    The stiffness matrix and the nodal forces associated with distributed loads are obtained for a nonhomogeneous anisotropic elastic beam element by the use of complementary energy. The element flexibility matrix is obtained by integrating the complementary-energy density corresponding to six beam...... equilibrium states, and then inverted and expanded to provide the element-stiffness matrix. Distributed element loads are represented via corresponding internal-force distributions in local equilibrium with the loads. The element formulation does not depend on assumed shape functions and can, in principle......, include any variation of cross-sectional properties and load variation, provided that these are integrated with sufficient accuracy in the process. The ability to represent variable cross-sectional properties, coupling from anisotropic materials, and distributed element loads is illustrated by numerical...

  9. Polar Functions for Anisotropic Gaussian Random Fields

    Directory of Open Access Journals (Sweden)

    Zhenlong Chen

    2014-01-01

    Full Text Available Let X be an (N, d-anisotropic Gaussian random field. Under some general conditions on X, we establish a relationship between a class of continuous functions satisfying the Lipschitz condition and a class of polar functions of X. We prove upper and lower bounds for the intersection probability for a nonpolar function and X in terms of Hausdorff measure and capacity, respectively. We also determine the Hausdorff and packing dimensions of the times set for a nonpolar function intersecting X. The class of Gaussian random fields that satisfy our conditions includes not only fractional Brownian motion and the Brownian sheet, but also such anisotropic fields as fractional Brownian sheets, solutions to stochastic heat equation driven by space-time white noise, and the operator-scaling Gaussian random field with stationary increments.

  10. Anisotropic instability of a stretching film

    Science.gov (United States)

    Xu, Bingrui; Li, Minhao; Deng, Daosheng

    2017-11-01

    Instability of a thin liquid film, such as dewetting arising from Van der Waals force, has been well studied, and is typically characterized by formation of many droplets. Interestingly, a thin liquid film subjected to an applied stretching during a process of thermal drawing is evolved into an array of filaments, i.e., continuity is preserved along the direction of stretching while breakup occurs exclusively in the plane of cross section. Here, to understand this anisotropic instability, we build a physical model by considering both Van der Waals force and the effect of stretching. By using the linear instability analysis method and then performing a numerical calculation, we find that the growth rate of perturbations at the cross section is larger than that along the direction of stretching, resulting in the anisotropic instability of the stretching film. These results may provide theoretical guidance to achieve more diverse structures for nanotechnology.

  11. Symmetry analysis for anisotropic field theories

    International Nuclear Information System (INIS)

    Parra, Lorena; Vergara, J. David

    2012-01-01

    The purpose of this paper is to study with the help of Noether's theorem the symmetries of anisotropic actions for arbitrary fields which generally depend on higher order spatial derivatives, and to find the corresponding current densities and the Noether charges. We study in particular scale invariance and consider the cases of higher derivative extensions of the scalar field, electrodynamics and Chern-Simons theory.

  12. Anisotropic diffusion tensor applied to temporal mammograms

    DEFF Research Database (Denmark)

    Karemore, Gopal; Brandt, Sami; Sporring, Jon

    2010-01-01

    changes related to  specific  effects  like  Hormonal  Replacement  Therapy  (HRT) and aging. Given effect-grouped patient data, we demonstrated how  anisotropic  diffusion  tensor  and  its  coherence  features computed in an anatomically oriented breast coordinate system followed by statistical learning...

  13. Anisotropic conducting films for electromagnetic radiation applications

    Science.gov (United States)

    Cavallo, Francesca; Lagally, Max G.; Rojas-Delgado, Richard

    2015-06-16

    Electronic devices for the generation of electromagnetic radiation are provided. Also provided are methods for using the devices to generate electromagnetic radiation. The radiation sources include an anisotropic electrically conducting thin film that is characterized by a periodically varying charge carrier mobility in the plane of the film. The periodic variation in carrier mobility gives rise to a spatially varying electric field, which produces electromagnetic radiation as charged particles pass through the film.

  14. Electromagnetic field representation in inhomogeneous anisotropic media

    Science.gov (United States)

    Mohsen, A.

    1973-01-01

    Some of the basic developments in the theory of electromagnetic field representation in terms of Hertz vectors are reviewed. A solution for the field in an inhomogeneous anisotropic medium is given in terms of the two Hertz vectors. Conditions for presentation of the field in terms of uncoupled transverse electric and transverse magnetic modes, in a general orthogonal coordinate system, are derived when the permeability and permittivity tensors have only diagonal components. These conditions are compared with some known special cases.

  15. Acoustic anisotropic wavefields through perturbation theory

    KAUST Repository

    Alkhalifah, Tariq Ali

    2013-09-01

    Solving the anisotropic acoustic wave equation numerically using finite-difference methods introduces many problems and media restriction requirements, and it rarely contributes to the ability to resolve the anisotropy parameters. Among these restrictions are the inability to handle media with η<0 and the presence of shear-wave artifacts in the solution. Both limitations do not exist in the solution of the elliptical anisotropic acoustic wave equation. Using perturbation theory in developing the solution of the anisotropic acoustic wave equation allows direct access to the desired limitation-free solutions, that is, solutions perturbed from the elliptical anisotropic background medium. It also provides a platform for parameter estimation because of the ability to isolate the wavefield dependency on the perturbed anisotropy parameters. As a result, I derive partial differential equations that relate changes in the wavefield to perturbations in the anisotropy parameters. The solutions of the perturbation equations represented the coefficients of a Taylor-series-type expansion of the wavefield as a function of the perturbed parameter, which is in this case η or the tilt of the symmetry axis. The expansion with respect to the symmetry axis allows use of an acoustic transversely isotropic media with a vertical symmetry axis (VTI) kernel to estimate the background wavefield and the corresponding perturbation coefficients. The VTI extrapolation kernel is about one-fourth the cost of the transversely isotropic model with a tilt in the symmetry axis kernel. Thus, for a small symmetry axis tilt, the cost of migration using a first-order expansion can be reduced. The effectiveness of the approach was demonstrated on the Marmousi model.

  16. Anisotropic cosmological solutions in massive vector theories

    International Nuclear Information System (INIS)

    Heisenberg, Lavinia; Kase, Ryotaro; Tsujikawa, Shinji

    2016-01-01

    In beyond-generalized Proca theories including the extension to theories higher than second order, we study the role of a spatial component v of a massive vector field on the anisotropic cosmological background. We show that, as in the case of the isotropic cosmological background, there is no additional ghostly degrees of freedom associated with the Ostrogradski instability. In second-order generalized Proca theories we find the existence of anisotropic solutions on which the ratio between the anisotropic expansion rate Σ and the isotropic expansion rate H remains nearly constant in the radiation-dominated epoch. In the regime where Σ/ H is constant, the spatial vector component v works as a dark radiation with the equation of state close to 1/3. During the matter era, the ratio Σ/ H decreases with the decrease of v . As long as the conditions |Σ| || H and v 2 || φ 2 are satisfied around the onset of late-time cosmic acceleration, where φ is the temporal vector component, we find that the solutions approach the isotropic de Sitter fixed point (Σ = 0 = v ) in accordance with the cosmic no-hair conjecture. In the presence of v and Σ the early evolution of the dark energy equation of state w DE in the radiation era is different from that in the isotropic case, but the approach to the isotropic value w DE (iso) typically occurs at redshifts z much larger than 1. Thus, apart from the existence of dark radiation, the anisotropic cosmological dynamics at low redshifts is similar to that in isotropic generalized Proca theories. In beyond-generalized Proca theories the only consistent solution to avoid the divergence of a determinant of the dynamical system corresponds to v = 0, so Σ always decreases in time.

  17. Bryan's effect and anisotropic nonlinear damping

    Science.gov (United States)

    Joubert, Stephan V.; Shatalov, Michael Y.; Fay, Temple H.; Manzhirov, Alexander V.

    2018-03-01

    In 1890, G. H. Bryan discovered the following: "The vibration pattern of a revolving cylinder or bell revolves at a rate proportional to the inertial rotation rate of the cylinder or bell." We call this phenomenon Bryan's law or Bryan's effect. It is well known that any imperfections in a vibratory gyroscope (VG) affect Bryan's law and this affects the accuracy of the VG. Consequently, in this paper, we assume that all such imperfections are either minimised or eliminated by some known control method and that only damping is present within the VG. If the damping is isotropic (linear or nonlinear), then it has been recently demonstrated in this journal, using symbolic analysis, that Bryan's law remains invariant. However, it is known that linear anisotropic damping does affect Bryan's law. In this paper, we generalise Rayleigh's dissipation function so that anisotropic nonlinear damping may be introduced into the equations of motion. Using a mixture of numeric and symbolic analysis on the ODEs of motion of the VG, for anisotropic light nonlinear damping, we demonstrate (up to an approximate average), that Bryan's law is affected by any form of such damping, causing pattern drift, compromising the accuracy of the VG.

  18. ARTc: Anisotropic reflectivity and transmissivity calculator

    Science.gov (United States)

    Malehmir, Reza; Schmitt, Douglas R.

    2016-08-01

    While seismic anisotropy is known to exist within the Earth's crust and even deeper, isotropic or even highly symmetric elastic anisotropic assumptions for seismic imaging is an over-simplification which may create artifacts in the image, target mis-positioning and hence flawed interpretation. In this paper, we have developed the ARTc algorithm to solve reflectivity, transmissivity as well as velocity and particle polarization in the most general case of elastic anisotropy. This algorithm is able to provide reflectivity solution from the boundary between two anisotropic slabs with arbitrary symmetry and orientation up to triclinic. To achieve this, the algorithm solves full elastic wave equation to find polarization, slowness and amplitude of all six wave-modes generated from the incident plane-wave and welded interface. In the first step to calculate the reflectivity, the algorithm solves properties of the incident wave such as particle polarization and slowness. After calculation of the direction of generated waves, the algorithm solves their respective slowness and particle polarization. With this information, the algorithm then solves a system of equations incorporating the imposed boundary conditions to arrive at the scattered wave amplitudes, and thus reflectivity and transmissivity. Reflectivity results as well as slowness and polarization are then tested in complex computational anisotropic models to ensure their accuracy and reliability. ARTc is coded in MATLAB ® and bundled with an interactive GUI and bash script to run on single or multi-processor computers.

  19. ANALYSIS OF DEFORMABILITY OF ANISOTROPIC AGRILLITE CLAYSTONES

    Directory of Open Access Journals (Sweden)

    Ponomaryov Andrey Budimirovicn

    2017-08-01

    Full Text Available In the paper, the results of deformability study of agrillite claystones are used for determination of the Jointed rock model parameters. The number of stamp, pressuremeter and compressive tests allowed to research anisotropic deformability of argillite claystone in vertical and horizontal direction. The following problems were solved during the study: 1 the in-place and laboratory experiments to calculate the anisotropy coefficient were done for anisotropic agrillite claystones with both natural moisture and total water saturation; 2 the deformation parameters were determined and the numerical simulation of the stress-strain state of claystone in field tests was carried out with the use of Plaxis 2D software application; 3 the comparative analysis was done for calculated claystone deformation and the values obtained during the in-place tests. The authors proved that agrillite claystones shows two times less deformation under loading in the horizontal direction than vertically. The ratio is obtained to determine the parameters for numerical simulation of the Jointed Rock model used as a practical tool for analysis of stress-strain behavior of anisotropic soils. The authors provided a recommended practice for consideration of specific properties of argillite claystones when carrying out foundation works.

  20. Longitudinal fluctuations and decorrelation of anisotropic flow

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Long-Gang [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Petersen, Hannah [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Qin, Guang-You [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Roy, Victor [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Wang, Xin-Nian [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Nuclear Science Division MS70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2016-12-15

    We investigate the decorrelation of 2nd and 3rd order anisotropic flow for charged particles in two different pseudo rapidity (η) windows by varying the pseudo rapidity gap, in an event-by-event (3+1)D ideal hydrodynamic model, with fluctuating initial conditions from A Multi-Phase Transport (AMPT) model. We visualize the parton distribution at initial state for Pb+Pb collisions at LHC and Au+Au collisions at RHIC, and demonstrate the longitudinal fluctuations originating from the asymmetry between forward and backward going participants, the fluctuations of the string length and the fluctuations due to finite number of partons at different beam energies. The decorrelation of anisotropic flow of final hadrons with large η gaps is found to originate from the spatial decorrelation along the longitudinal direction in the AMPT initial conditions through hydrodynamic evolution. The agreement between our results and recent CMS data in most centralities suggests that the string-like mechanism of initial parton production in AMPT model captures the initial longitudinal fluctuation that is responsible for the measured decorrelation of anisotropic flow in Pb+Pb collisions at LHC. Our predictions for Au+Au collisions at the highest RHIC energy show stronger longitudinal decorrelation than at LHC, indicating larger longitudinal fluctuations at lower beam energies.

  1. Geopolymer as an adsorbent of heavy metal: A review

    Science.gov (United States)

    Ariffin, Nurliyana; Abdullah, Mohamad Mustafa Al Bakri; Zainol, Remy Rozainy Mohd Arif; Murshed, Mohd Fared

    2017-09-01

    This paper reviews about geopolymer based adsorbent focusing in the removal of heavy metal. The reviews include fundamental and types of material used in the formation of adsorbents. Geopolymer based adsorbent got attention recently due to its unique three-dimensional network structure, with fixed size pores and paths that allow certain heavy metal to pass through. Most materials that applied as adsorbent such as fly ash, metakaolin, kaolin and dolomite. A lot of sludge nowadays only dumped in the landfill which can be used as one of new materials as geopolymer based adsorbent.

  2. The adsorber loop concept for the contact between seawater and adsorber granulate

    International Nuclear Information System (INIS)

    Koske, P.H.; Ohlrogge, K.

    1984-01-01

    For the production of 1 kg uranium from seawater about 10 9 kg seawater - depending on the extraction efficiency - have to be processed in a production plant. Such high seawater flows have to be put through adsorber beds the area of which depends on the flow velocity of the water in the bed. For a typical polyamidoxim (PAO) adsorber granulate with a grain size distribution of 0.3 to 1.2 mm the velocity in a fluidized bed is limited to about 1 cm/s in order to prevent carry out of the adsorber material. The consequences of this rather low bed velocity are large and expensive bed areas for technical production plants. The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the water before this is leaving the adsorption unit. This concept enables considerably higher seawater velocities thus reducing the bed area. Theoretical considerations are presented together with experimental results from field tests. (author)

  3. Understanding conoscopic interference patterns in anisotropic crystals

    Science.gov (United States)

    Olorunsola, Oluwatobi Gabriel

    The interference patterns observed in conoscopy are important in studying the optical and geometrical properties of anisotropic materials. They have also been used to identify minerals and to explore the structure of biological tissues. In a conoscopic interferometer, an optically anisotropic specimen is placed between two crossed linear polarizers and illuminated by a convergent light beam. The interference patterns are produced because in an anisotropic material an incident light is split into two eigenwaves, namely the ordinary and the extraordinary waves. We report our work on the theoretical simulation and experimental observation of the conoscopic interference patterns in anisotropic crystals. In our simulation, the interference patterns are decomposed into fringes of isogyres and isochromates. For each light propagation direction inside the crystal there exist two eigenwaves that have their own characteristic velocities and vibration directions. The isogyres are obtained by computing the angle between the polarization of the incident light and the vibration directions of the two eigenwaves. The isochromates are obtained by computing the phase retardance between the two eigenwaves inside the crystal. The interference patterns are experimentally observed in several crystals, with their optic axes either parallel or perpendicular to their surfaces. An external electric field is applied to deform the crystals from uniaxial to biaxial. The results of our experimental observation agree well with our computer simulation. In conventional interferometers the isochromatic interference fringes are observed by using a circular polarizer and a circular analyzer, both constructed by a linear polarizer and a quarter wave plate. However, due to the dispersion of the quarter wave plates, the phase-retardance between the two light waves inside the quarter wave plates is wavelength-dependent, which results in different conoscopic interference patterns for different colors of

  4. Layer-dependent surface potential of phosphorene and anisotropic/layer-dependent charge transfer in phosphorene-gold hybrid systems.

    Science.gov (United States)

    Xu, Renjing; Yang, Jiong; Zhu, Yi; Yan, Han; Pei, Jiajie; Myint, Ye Win; Zhang, Shuang; Lu, Yuerui

    2016-01-07

    The surface potential and the efficiency of interfacial charge transfer are extremely important for designing future semiconductor devices based on the emerging two-dimensional (2D) phosphorene. Here, we directly measured the strong layer-dependent surface potential of mono- and few-layered phosphorene on gold, which is consistent with the reported theoretical prediction. At the same time, we used an optical way photoluminescence (PL) spectroscopy to probe charge transfer in the phosphorene-gold hybrid system. We firstly observed highly anisotropic and layer-dependent PL quenching in the phosphorene-gold hybrid system, which is attributed to the highly anisotropic/layer-dependent interfacial charge transfer.

  5. Negatively charged ions on Mg(0001) surfaces: appearance and origin of attractive adsorbate-adsorbate interactions.

    Science.gov (United States)

    Cheng, Su-Ting; Todorova, Mira; Freysoldt, Christoph; Neugebauer, Jörg

    2014-09-26

    Adsorption of electronegative elements on a metal surface usually leads to an increase in the work function and decrease in the binding energy as the adsorbate coverage rises. Using density-functional theory calculations, we show that Cl adsorbed on a Mg(0001) surface complies with these expectations, but adsorption of {N,O,F} causes a decrease in the work function and an increase in the binding energy. Analyzing the electronic structure, we show that the presence of a highly polarizable electron spill-out in front of Mg(0001) causes this unusual adsorption behavior and is responsible for the appearance of a hitherto unknown net-attractive lateral electrostatic interaction between same charged adsorbates.

  6. Strongly anisotropic in-plane thermal transport in single-layer black phosphorene.

    Science.gov (United States)

    Jain, Ankit; McGaughey, Alan J H

    2015-02-17

    Using first principles calculations, we predict the thermal conductivity of the two-dimensional materials black phosphorene and blue phosphorene. Black phosphorene has an unprecedented thermal conductivity anisotropy ratio of three, with predicted values of 110 W/m-K and 36 W/m-K along its armchair and zigzag directions at a temperature of 300 K. For blue phosphorene, which is isotropic with a zigzag structure, the predicted value is 78 W/m-K. The two allotropes show strikingly different thermal conductivity accumulation, with phonons of mean free paths between 10 nm and 1 μm dominating in black phosphorene, while a much narrower band of mean free paths (50-200 nm) dominate in blue phosphorene. Black phosphorene shows intriguing potential for strain-tuning of its thermal conductivity tensor.

  7. Strongly anisotropic in-plane thermal transport in single-layer black phosphorene

    OpenAIRE

    Ankit Jain; Alan J. H. McGaughey

    2015-01-01

    Using first principles calculations, we predict the thermal conductivity of the two-dimensional materials black phosphorene and blue phosphorene. Black phosphorene has an unprecedented thermal conductivity anisotropy ratio of three, with predicted values of 110?W/m-K and 36?W/m-K along its armchair and zigzag directions at a temperature of 300?K. For blue phosphorene, which is isotropic with a zigzag structure, the predicted value is 78?W/m-K. The two allotropes show strikingly different ther...

  8. Exchange interaction of strongly anisotropic tripodal erbium single-ion magnets with metallic surfaces

    DEFF Research Database (Denmark)

    Dreiser, Jan; Wäckerlin, Christian; Ali, Md. Ehesan

    2014-01-01

    We present a comprehensive study of Er(trensal) single-ion magnets deposited in ultrahigh vacuum onto metallic surfaces. X-ray photoelectron spectroscopy reveals that the molecular structure is preserved after sublimation, and that the molecules are physisorbed on Au(111) while they are chemisorbed....... Furthermore XMCD indicates a weak antiferromagnetic exchange coupling between the single-ion magnets and the ferromagnetic Ni/Cu(100) substrate. For the latter case, spin-Hamiltonian fits to the XMCD M(H) suggest a significant structural distortion of the molecules. Scanning tunneling microscopy reveals...

  9. Anisotropic Thermoelectric Devices Made from Single-Crystal Semimetal Microwires in Glass Coating

    Science.gov (United States)

    Konopko, L. A.; Nikolaeva, A. A.; Kobylianskaya, A. K.; Huber, T. E.

    2018-04-01

    Thermoelectric heat conversion based on the Seebeck and Peltier effects generated at the junction between two materials of type-n and type-p is well known. Here, we present a demonstration of an unconventional thermoelectric energy conversion that is based on a single element made of an anisotropic material. In such materials, a heat flow generates a transverse thermoelectric electric field lying across the heat flow. Potentially, in applications involving miniature devices, the anisotropic thermoelectric (AT) effect has the advantage over traditional thermoelectrics that it simplifies the thermoelectric generator architecture. This is because the generator can be made of a single thermoelectric material without the complexity of a series of contacts forming a pile. A feature of anisotropic thermoelectrics is that the thermoelectric voltage is proportional to the element length and inversely proportional to the effective thickness. The AT effect has been demonstrated with artificial anisotropic thin film consisting of layers of alternating thermoelectric type, but there has been no demonstration of this effect in a long single-crystal. Electronic transport measurements have shown that the semimetal bismuth is highly anisotropic. We have prepared an experimental sample consisting of a 10-m-long glass-insulated single-crystal tin-doped bismuth microwire (d = 4 μm). Crucial for this experiment is the ability to grow the microwire as a single-crystal using a technique of recrystallization with laser heating and under a strong electric field. The sample was wound as a spiral, bonded to a copper disk, and used in various experiments. The sensitivity of the sample to heat flow is as high as 10-2 V/W with a time constant τ of about 0.5 s.

  10. Intermittent Anisotropic Turbulence Detected by THEMIS in the Magnetosheath

    Science.gov (United States)

    Macek, W. M.; Wawrzaszek, A.; Kucharuk, B.; Sibeck, D. G.

    2017-12-01

    Following our previous study of Time History of Events and Macroscale Interactions during Substorms (THEMIS) data, we consider intermittent turbulence in the magnetosheath depending on various conditions of the magnetized plasma behind the Earth’s bow shock and now also near the magnetopause. Namely, we look at the fluctuations of the components of the Elsässer variables in the plane perpendicular to the scale-dependent background magnetic fields and along the local average ambient magnetic fields. We have shown that Alfvén fluctuations often exhibit strong anisotropic non-gyrotropic turbulent intermittent behavior resulting in substantial deviations of the probability density functions from a normal Gaussian distribution with a large kurtosis. In particular, for very high Alfvénic Mach numbers and high plasma beta, we have clear anisotropy with non-Gaussian statistics in the transverse directions. However, along the magnetic field, the kurtosis is small and the plasma is close to equilibrium. On the other hand, intermittency becomes weaker for moderate Alfvén Mach numbers and lower values of the plasma parameter beta. It also seems that the degree of intermittency of turbulence for the outgoing fluctuations propagating relative to the ambient magnetic field is usually similar as for the ingoing fluctuations, which is in agreement with approximate equipartition of energy between these oppositely propagating Alfvén waves. We believe that the different characteristics of this intermittent anisotropic turbulent behavior in various regions of space and astrophysical plasmas can help identify nonlinear structures responsible for deviations of the plasma from equilibrium.

  11. Adsorption equilibria and kinetics for phenol and cresol onto polymeric adsorbents: effects of adsorbents/adsorbates structure and interface.

    Science.gov (United States)

    Liu, Fu-Qiang; Xia, Ming-Fang; Yao, San-Li; Li, Ai-Min; Wu, Hai-Suo; Chen, Jin-Long

    2008-04-01

    Phenol and cresol (o-, m-, and p-) were selected as the adsorbates with different dipole moment (cresol>phenol, methyl being electron-drawing group) and solubility (phenol>cresol, methyl being hydrophobic group). Macropore polymers (NDA-1800 and XAD-4), hypercrosslinked polymers (NDA-100), and chemically modified adsorbents (NDA-150 and NDA-99), were comparatively used to investigate the adsorption properties including equilibria, thermodynamics and kinetics. First, all of the results about equilibria show that the adsorption data fit well to the Freundlich model. The adsorption capacity of NDA-99 and NDA-150 especially for phenol is larger in a certain extent than other three types of polymers. The hydrophobic interaction from large specific surface was mainly occurred, while the polar groups containing oxygen and amine markedly enhance the adsorption process via hydrogen interaction. Furthermore, the adsorption amount for NDA-99 and XAD-4 decrease linearly with the solubility of solutes tested. Then, the negative values of enthalpy demonstrate the predominantly exothermic and physical solid-extraction processes. Finally, the relatively more rapid adsorption process could be found onto NDA-150 than NDA-99, with the reason of the double larger pore size of the former. In conclusion, solubility of solute, together with surface area, pore size and modified groups, extremely exerts influences to the adsorption performances.

  12. Adsorbing staircase polygons subject to a force

    Science.gov (United States)

    Beaton, Nicholas R.

    2017-12-01

    We study several models of staircase polygons on the 45\\circ rotated square lattice, which interact with an impenetrable surface while also being pushed towards or pulled away from the surface by a force. The surface interaction is governed by a fugacity a and the force by a fugacity y. Staircase polygons are simplifications of more general self-avoiding polygons, a well-studied model of interacting ring polymers. For this simplified case we are able to exactly determine the limiting free energy in the full a-y plane, and demonstrate that staircase polygons exhibit four different phases, including a ‘mixed’ adsorbed-ballistic phase.

  13. (3+1)-dimensional anisotropic fluid dynamics with a lattice QCD equation of state arXiv

    CERN Document Server

    McNelis, M.; Heinz, U.

    Anisotropic hydrodynamics improves upon standard dissipative fluid dynamics by treating certain large dissipative corrections non-perturbatively. Relativistic heavy-ion collisions feature two such large dissipative effects: (i) Strongly anisotropic expansion generates a large shear stress component which manifests itself in very different longitudinal and transverse pressures, especially at early times. (ii) Critical fluctuations near the quark-hadron phase transition lead to a large bulk viscous pressure on the conversion surface between hydrodynamics and a microscopic hadronic cascade description of the final collision stage. We present a new dissipative hydrodynamic formulation for non-conformal fluids where both of these effects are treated nonperturbatively. The evolution equations are derived from the Boltzmann equation in the 14-moment approximation, using an expansion around an anisotropic leading-order distribution function with two momentum-space deformation parameters, accounting for the longitudin...

  14. Testing strong interaction theories

    International Nuclear Information System (INIS)

    Ellis, J.

    1979-01-01

    The author discusses possible tests of the current theories of the strong interaction, in particular, quantum chromodynamics. High energy e + e - interactions should provide an excellent means of studying the strong force. (W.D.L.)

  15. FePt/Co core/shell nanoparticle-based anisotropic nanocomposites and their exchange spring behavior.

    Science.gov (United States)

    Li, Deyao; Wang, Hui; Ma, Zhenhui; Liu, Xin; Dong, Ying; Liu, Zhiqi; Zhang, Tianli; Jiang, Chengbao

    2018-02-22

    Anisotropic exchange-coupled nanocomposites provide us a salient candidate for the new generation of permanent magnets owing to their huge predicted maximum energy product. However, previous research basically focused on thin films or bulk materials and the impact of easy-axis alignment on the exchange coupling behavior is not clear. Herein, strongly coupled FePt/Co core/shell nanoparticles with single-phase-like hysteresis loops were synthesized by the seed mediated method. Then, these nanoparticles were successfully aligned by the external magnetic field and fixed in an acrylic binder, so that FePt/Co core/shell nanoparticle-based anisotropic nanocomposites were obtained. The nanocomposites exhibited high degree of orientation as indicated by the increased remanence ratio from 0.62 for isotropic nanoparticles to 0.78 for anisotropic nanocomposites. However, a visible kink in the demagnetization curve was observed around the zero field, implying the exchange spring behavior. This result suggests that the aligned FePt cores impose a stronger overall dipolar field in Co shells and finally, force the Co shells to reverse at a low field before the switch of FePt cores. Our research extends the preparation methods of anisotropic hard/soft-phase nanocomposites and might be helpful for the design of high-performance anisotropic exchange-coupled nanocomposites.

  16. Development of adsorbents for recovery of uranium from seawater

    International Nuclear Information System (INIS)

    Egawa, Hiroaki; Furusaki, Shintaro.

    1987-01-01

    The largest subject for putting the extraction of uranium from seawater in practical use is the development of high performance adsorbents for uranium. In this paper, the way of thinking about the development of adsorbents for extracting uranium from seawater and the recent reports on this subject are described. Next, the research on the adsorbing capacity and adsorbing rate of the adsorbents developed so far is summarized, and the way of thinking about the evaluation of adsorbent performance which is the base of the design of a system for extracting uranium from seawater is explained, taking amidoxime type adsorbent as the example. For Japan where energy resources are scant, the uranium contained in seawater, which is estimated to be about 4.2 billion t, is the most luring important element. Uranium is contained in seawater is very low concentration of 3 ppb, and exists as anion complex salt. In 1960s, the Harwell Atomic Energy Research Establishment in UK found out that titanium oxide hydrate is the most promising as the adsorbent. Also a number of organic absorbents have been developed. In order to bring adsorbents in contact with seawater, pumping, ocean current and wave force are utilized. Adsorbents are in spherical, fiber and film forms, and held as fixed beds and fluidized beds. (Kako, I.) 48 refs

  17. Graphene nanosheets and graphite oxide as promising adsorbents for removal of organic contaminants from aqueous solution.

    Science.gov (United States)

    Ji, Liangliang; Chen, Wei; Xu, Zhaoyi; Zheng, Shourong; Zhu, Dongqiang

    2013-01-01

    Graphenes are an emerging class of carbon nanomaterials whose adsorption properties toward organic compounds have not been well understood. In the present study, graphene nanosheets were prepared by reoxidation and abrupt heating of graphite oxide, which was prepared by sequential chemical oxidation of commercial nonporous graphite powder. Adsorption properties of three aromatic compounds (naphthalene, 2-naphthol, and 1-naphthylamine) and one pharmaceutical compound (tylosin) on graphene nanosheets and graphite oxide were examined to explore the potential of these two adsorbents for the removal of organic contaminants from aqueous solutions. Compared with the literature data of adsorption on carbon nanotubes, adsorption of bulky, flexible tylosin on graphene nanosheets exhibited markedly faster adsorption kinetics, which can be attributed to their opened-up layer structure. Graphene nanosheets and graphite oxide showed similar sequences of adsorption affinity: 1-naphthylamine > 2-naphthol > tylosin > naphthalene (with much larger differences observed on graphite oxide). It was proposed that the strong adsorption of the three aromatic compounds was mainly due to π-π electron donor-acceptor interactions with the graphitic surfaces of adsorbents. Additionally, Lewis acid-base interaction was likely an important factor contributing to the strong adsorption of 1-naphthylamine and tylosin, especially for the O-functionality-abundant graphite oxide. After being normalized on the basis of adsorbent surface area, adsorption affinities of all four tested adsorbates on graphene nanosheets were very close to those on nonporous graphite powder, reflecting complete accessibility of the adsorbent surface area in adsorption. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  18. Anisotropic resonant scattering from polymer photonic crystals.

    Science.gov (United States)

    Haines, Andrew I; Finlayson, Chris E; Snoswell, David R E; Spahn, Peter; Hellmann, G Peter; Baumberg, Jeremy J

    2012-11-20

    Hyperspectral goniometry reveals anisotropic scattering which dominates the visual appearance of self-assembled polymer opals. The technique allows reconstruction of the reciprocal-space of nanostructures, and indicates that chain defects formed during shear-ordering are responsible for the anisotropy in these samples. Enhanced scattering with improving order is shown to arise from increased effective refractive index contrast, while broadband background scatter is suppressed by absorptive dopants. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. An approach to anisotropic cosmologies. 6

    International Nuclear Information System (INIS)

    Raychaudhuri, A.K.

    1989-01-01

    In this paper the motivation for the study of anisotropic cosmological models is set out. Then the mathematical basis for the study of such models as well as the description of some of the exact solutions of this genre are given. Killing vectors that spell out spacetime symmetries, are defined and the Bianchi classification of spacetimes based on the structure of the Killing vectors described. After a consideration of the kinematics of matter flow some of the known solutions are presented and their properties described. (author)

  20. Creating an anisotropic plasma resistivity with waves

    International Nuclear Information System (INIS)

    Fisch, N.J.; Boozer, A.H.

    1980-05-01

    An anisotropic plasma resistivity may be created by preferential heating of electrons traveling in one direction. This can result in a steady-state toroidal current in a tokamak even in the absence of net wave momentum. In fact, at high wave phase velocities, the current associated with the change in resistivity is greater than that associated with net momentum input. An immediate implication is that other waves, such as electron cyclotron waves, may be competitive with lower-hybrid waves as a means for generating current. An analytical expression is derived for the current generated per power dissipated which agrees remarkably well with numerical calculations

  1. Generalised model for anisotropic compact stars

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Raj Kumar Goel Institute of Technology, Department of Mathematics, Ghaziabad, Uttar Pradesh (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India); Deb, Debabrata [Indian Institute of Engineering Science and Technology, Shibpur, Department of Physics, Howrah, West Bengal (India)

    2016-12-15

    In the present investigation an exact generalised model for anisotropic compact stars of embedding class 1 is sought with a general relativistic background. The generic solutions are verified by exploring different physical aspects, viz. energy conditions, mass-radius relation, stability of the models, in connection to their validity. It is observed that the model presented here for compact stars is compatible with all these physical tests and thus physically acceptable as far as the compact star candidates RXJ 1856-37, SAX J 1808.4-3658 (SS1) and SAX J 1808.4-3658 (SS2) are concerned. (orig.)

  2. Effective Medium Theory for Anisotropic Metamaterials

    KAUST Repository

    Zhang, Xiujuan

    2017-11-12

    This dissertation includes the study of effective medium theories (EMTs) and their applications in describing wave propagation in anisotropic metamaterials, which can guide the design of metamaterials. An EMT based on field averaging is proposed to describe a peculiar anisotropic dispersion relation that is linear along the symmetry line but quadratic in the perpendicular direction. This dispersion relation is associated with the topological transition of the iso-frequency contours (IFCs), suggesting interesting wave propagation behaviors from beam shaping to beam splitting. In the framework of coherent potential approximation, an analytical EMT is further developed, with the ability to build a direct connection between the microscopic structure and the macroscopic material properties, which overcomes the requirement of prior knowledge of the field distributions. The derived EMT is valid beyond the long-wavelength limit. Using the EMT, an anisotropic zero-index metamaterial is designed. Moreover, the derived EMT imposes a condition that no scattered wave is generated in the ambient medium, which suggests the input signal cannot detect any object that might exist, making it invisible. Such correspondence between the EMT and the invisibilityinspires us to explore the wave cloaking in the same framework of coherent potential approximation. To further broaden the application realm of EMT, an EMT using the parameter retrieval method is studied in the regimes where the previously-developed EMTs are no longer accurate. Based on this study, in conjunction with the EMT mentioned above, a general scheme to realize coherent perfect absorption (CPA) in anisotropic metamaterials is proposed. As an exciting area in metamaterials, the field of metasurfaces has drawn great attention recently. As an easily attainable device, a grating may be the simplest version of metasurfaces. Here, an analytical EMT for gratings made of cylinders is developed by using the multiple scattering

  3. RELATIVISTIC CYCLOTRON INSTABILITY IN ANISOTROPIC PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    López, Rodrigo A.; Moya, Pablo S.; Muñoz, Víctor; Valdivia, J. Alejandro [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Navarro, Roberto E.; Araneda, Jaime A. [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Viñas, Adolfo F., E-mail: rlopez186@gmail.com [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, MD 20771 (United States)

    2016-11-20

    A sufficiently large temperature anisotropy can sometimes drive various types of electromagnetic plasma micro-instabilities, which can play an important role in the dynamics of relativistic pair plasmas in space, astrophysics, and laboratory environments. Here, we provide a detailed description of the cyclotron instability of parallel propagating electromagnetic waves in relativistic pair plasmas on the basis of a relativistic anisotropic distribution function. Using plasma kinetic theory and particle-in-cell simulations, we study the influence of the relativistic temperature and the temperature anisotropy on the collective and noncollective modes of these plasmas. Growth rates and dispersion curves from the linear theory show a good agreement with simulations results.

  4. Analysis of anisotropic shells containing flowing fluid

    International Nuclear Information System (INIS)

    Lakis, A.A.

    1983-01-01

    A general theory for the dynamic analysis of anisotropic thin cylindrical shells containing flowing fluid is presented. The shell may be uniform or non-uniform, provided it is geometrically axially symmetric. This is a finite- element theory, using cylindrical finite elements, but the displacement functions are determined by using classical shell theory. A new solution of the wave equation of the liquid finite element leads to an expression of the fluid pressure, p, as a function of the nodal displacements of the element and three operative forces (inertia, centrifugal and Coriolis) of the moving fluid. (Author) [pt

  5. Structure of Irreversibly Adsorbed Star Polymers

    Science.gov (United States)

    Akgun, Bulent; Aykan, Meryem Seyma; Canavar, Seda; Satija, Sushil K.; Uhrig, David; Hong, Kunlun

    Formation of irreversibly adsorbed polymer chains on solid substrates have a huge impact on the wetting, glass transition, aging and polymer chain mobility in thin films. In recent years there has been many reports on the formation, kinetics and dynamics of these layers formed by linear homopolymers. Recent studies showed that by varying the number of polymer arms and arm molecular weight one can tune the glass transition temperature of thin polymer films. Using polymer architecture as a tool, the behavior of thin films can be tuned between the behavior of linear chains and soft colloids. We have studied the effect of polymer chain architecture on the structure of dead layer using X-ray reflectivity (XR) and atomic force microscopy. Layer thicknesses and densities of flattened and loosely adsorbed chains has been measured for linear, 4-arm, and 8-arm star polymers with identical total molecular weight as a function of substrate surface energy, annealing temperature and annealing time. Star polymers have been synthesized using anionic polymerization. XR measurements showed that 8-arm star PS molecules form the densest and the thickest dead layers among these three molecules.

  6. Dye sequestration using agricultural wastes as adsorbents

    Directory of Open Access Journals (Sweden)

    Kayode Adesina Adegoke

    2015-12-01

    Full Text Available Color is a visible pollutant and the presence of even minute amounts of coloring substance makes it undesirable due to its appearance. The removal of color from dye-bearing effluents is a major problem due to the difficulty in treating such wastewaters by conventional treatment methods. The most commonly used methods for color removal are biological oxidation and chemical precipitation. However, these processes are effective and economic only in the case where the solute concentrations are relatively high. Most industries use dyes and pigments to color their products. The presence of dyes in effluents is a major concern due to its adverse effect on various forms of life. The discharge of dyes in the environment is a matter of concern for both toxicological and esthetical reasons. It is evident from a literature survey of about 283 recently published papers that low-cost adsorbents have demonstrated outstanding removal capabilities for dye removal and the optimal equilibrium time of various dyes with different charcoal adsorbents from agricultural residues is between 4 and 5 h. Maximum adsorptions of acidic dyes were obtained from the solutions with pH 8–10. The challenges and future prospects are discussed to provide a better framework for a safer and cleaner environment.

  7. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    Science.gov (United States)

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  8. Natural adsorbents of dyes from aqueous solution

    Science.gov (United States)

    Rahmani, Meryem; El Hajjaji, souad; Dahchour, Abdelmalek; El M'Rabet, Mohammadine

    2017-04-01

    Contamination of natural waters is a current environmental problem and lot of work has been done to find methods for its, prevention and remediation such as ionic exchange, adsorption on active carbon, filtration, electrolysis, biodegradation …etc. Adsorption is one of the most applied methods according to its effectiveness and easy management. Some adsorbents with good properties such as active alumina, zeolites, crop residues … etc, are suitable to substitute usual active carbon. This study aimed at the removal of dyes using oil shale as natural support, and its optimization by factorial experiment. Three factors were considered namly:pollutant concentration, pH and weight of the adsorbent. Tests have been performed with cationic and anionic dyes. Experimental results show that pseudo-first-order kinetic model provided the best fit to the experimental data for the adsorption by the oil shale. Langmuir, Freundlich and Temkin isotherm models were tested to fit experimental data, the adsorption equilibrium was well described by Freundlich isotherm for methylorange and Temkin for methyl blue. Analysis were completed by oil shale characterization educing XRD, IR, XRF techniques, and cationic exchange capacity.

  9. Anisotropic bias dependent transport property of defective phosphorene layer

    Science.gov (United States)

    Umar Farooq, M.; Hashmi, Arqum; Hong, Jisang

    2015-01-01

    Phosphorene is receiving great research interests because of its peculiar physical properties. Nonetheless, no systematic studies on the transport properties modified due to defects have been performed. Here, we present the electronic band structure, defect formation energy and bias dependent transport property of various defective systems. We found that the defect formation energy is much less than that in graphene. The defect configuration strongly affects the electronic structure. The band gap vanishes in single vacancy layers, but the band gap reappears in divacancy layers. Interestingly, a single vacancy defect behaves like a p-type impurity for transport property. Unlike the common belief, we observe that the vacancy defect can contribute to greatly increasing the current. Along the zigzag direction, the current in the most stable single vacancy structure was significantly increased as compared with that found in the pristine layer. In addition, the current along the armchair direction was always greater than along the zigzag direction and we observed a strong anisotropic current ratio of armchair to zigzag direction. PMID:26198318

  10. Aligned CuO nanorod arrays: fabrication and anisotropic ferromagnetism

    Science.gov (United States)

    Liu, Liqing; Hong, Kunquan; Ge, Xing; Xu, Mingxiang

    2014-06-01

    Copper oxide (CuO) is a p-type semiconductor with a band gap of 1.2 eV, which is well known in high-temperature superconductor and antiferromagnetic (AFM) materials through Cu-O-Cu super-exchange interaction. In this paper, we report the strong anisotropic ferromagnetism (FM) in aligned CuO nanorod arrays synthesized by a microwave-assisted hydrothermal method. The transmission electron microscopy (TEM) image shows that the CuO nanorod consists of a large number of smaller nanorods with almost the same growth direction. The X-ray diffraction (XRD) pattern indicates that the CuO nanorods are well crystallized with highly preferred orientation of the [020] direction. These CuO nanorod arrays show room-temperature ferromagnetism, with strong magnetic anisotropy when the magnetic field is applied perpendicular or parallel to the rod axis. This phenomenon of room-temperature ferromagnetism in those aligned CuO nanorods might originate from uncompensated surface spins and shape anisotropy of the nanorods.

  11. Rotational diffusion in polymer nanocomposites as probed by anisotropic particles

    Science.gov (United States)

    Clarke, Laura

    2014-03-01

    Metal nanoparticles strongly absorb specific wavelengths of light with no (or only a very weak) radiative relaxation by which to release this energy. As a result, the absorbed energy is efficiently converted to local heat (a photothermal effect). With an effective cross-section of up to 10 times its physical size, each particle acts as a ``super-sized'' absorber even when embedded within a transparent material environment such as a polymer, resulting in dramatic heating originating at the particles. Thus, with spatially-uniform illumination, one can metaphorically reach inside a polymer nanocomposite and apply heat to pre-selected subsets (e.g., causing them to dramatically change properties due to actuation, cross-linking, crystallization, or chemical reaction) without heating the sample surface or strongly affecting the remainder of the material. By utilizing optically-accessible additives including the particles themselves, the thermal gradient from the particle outward can be experimentally determined. In particular, rotational diffusion of anisotropic particles can be used to measure the temperature at the nanoparticle, which is the warmest point in a polymeric film or nanofiber under photothermal heating. Conversely, the same technique can be utilized to measure polymer dynamics in nanocomposites in the immediate vicinity of the particle. Funding: National Science Foundation CMMI-1069108.

  12. Anisotropic behaviour of transmission through thin superconducting NbN film in parallel magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Šindler, M., E-mail: sindler@fzu.cz [Institute of Physics ASCR, v. v. i., Cukrovarnická 10, CZ-162 53 Praha 6 (Czech Republic); Tesař, R. [Institute of Physics ASCR, v. v. i., Cukrovarnická 10, CZ-162 53 Praha 6 (Czech Republic); Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, CZ-121 16 Praha (Czech Republic); Koláček, J. [Institute of Physics ASCR, v. v. i., Cukrovarnická 10, CZ-162 53 Praha 6 (Czech Republic); Skrbek, L. [Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, CZ-121 16 Praha (Czech Republic)

    2017-02-15

    Highlights: • Transmission through thin NbN film in parallel magnetic field exhibits strong anisotropic behaviour in the terahertz range. • Response for a polarisation parallel with the applied field is given as weighted sum of superconducting and normal state contributions. • Effective medium approach fails to describe response for linear polarisation perpendicular to the applied magnetic field. - Abstract: Transmission of terahertz waves through a thin layer of the superconductor NbN deposited on an anisotropic R-cut sapphire substrate is studied as a function of temperature in a magnetic field oriented parallel with the sample. A significant difference is found between transmitted intensities of beams linearly polarised parallel with and perpendicular to the direction of applied magnetic field.

  13. Wideband and High-Efficiency Reflective Polarization Conversion Metasurface Based on Anisotropic Metamaterials

    Science.gov (United States)

    Zheng, Qi; Guo, Chenjiang; Yuan, Pengliang; Ren, Yu-Hui; Ding, Jun

    2018-02-01

    In this paper, we propose a wideband and high-efficiency reflective polarization conversion metasurface (PCM) based on anisotropic metamaterials. The PCM has a period of sub-wavelength and simple design with a double-meander-line-shaped resonator printed on a metallic copper plate backed dielectric substrate. Owing to strong anisotropic properties and multiple plasmon resonances at neighboring frequencies, the PCM has a simulated fractional bandwidth of 82.3% from 8.40 GHz to 20.15 GHz with a polarization conversion ratio over 0.9. Numerical analysis and experimental validation are carried out to study the polarization conversion characteristics of the PCM. In addition, the mechanisms are analyzed in detail on the basis of multiple plasmon resonances and surface magnetic field distributions, respectively. The measured and simulated results obtained are in good agreement, which validates the effectiveness of the simulations and analysis.

  14. New type of amidoxime-group-containing adsorbent for the recovery of uranium from seawater. III. Recycle use of adsorbent

    International Nuclear Information System (INIS)

    Omichi, H.; Katakai, A.; Sugo, T.; Okamoto, J.

    1986-01-01

    An amidoxime-group adsorbent for recovering uranium from seawater was made by radiation-induced graft polymerization of acrylonitrile onto polymeric fiber, followed by amidoximation. Uranium adsorption of the adsorbent contacted with seawater in a column increased with the increase in flow rate, then leveled off. The relationship between uranium adsorption in a batch process and the ratio of the amount of seawater to that of adsorbent was found to be effective in evaluating adsorbent contacted with any amount of seawater. The conditioning of the adsorbent with an alkaline solution at higher temperature (∼80 0 C) after the acid desorption recovered the adsorption ability to the original level. This made it possible to apply the adsorbent to recycle use. On the other hand, the adsorbent conditioned at room temperature or that without conditioning lost adsorption ability during recycle use. The increase in water uptake was observed as one of the physical changes produced during recycle use of the alkaline-conditioned adsorbent, while the decrease in water uptake was observed with the unconditioned adsorbent. The IR spectra of the adsorbent showed a probability of reactions of amidoxime groups with acid and alkaline solutions, which can explain the change in uranium adsorption during the adsorption-desorption cycle

  15. Comparison with adsorption of Re (VII) by two different γ-radiation synthesized silica-grafting of vinylimidazole/4-vinylpyridine adsorbents.

    Science.gov (United States)

    Xiao, Pu; Han, Dong; Zhai, Maolin; Xu, Ling; Li, Huibo

    2017-02-15

    Two silica gel based adsorbents for Re (VII), i.e. SS-MPTS-VIMH and SS-MPTS-VPQ, were synthesised. Silica gel was used as the matrix for γ-radiation grafting, and the monomer of 1-vinyl imidazole (VIM) and 4-vinylpyridine (4-VP) was grafted onto the silica silanized by methacryloxy propyl trimethoxyl silane, respectively. A VIM concentration of 2molL -1 and an absorbed dose of 30kGy were the optimal grafting conditions for adsorbent SS-MPTS-VIM, and a 4-VP concentration of 4molL -1 and an absorbed dose of 40kGy were the optimal grafting conditions for adsorbent SS-MPTS-VP. At the certain condition, the grafting yield of SS-MPTS-VIM was 30.1% and that of SS-MPTS-VP was 21.0%. The adsorption capacity of adsorbent SS-MPTS-VIMH was 145.99mgg -1 and that of SS-MPTS-VPQ was 71.08mgg -1 according to the Langmuir model. The adsorbent SS-MPTS-VPQ had better adsorption properties of acid resistance and anti-interference than SS-MPTS-VIMH. Dynamic column experiments showed that protonated adsorbent SS-MTPS-VIMH could be recycled with good performance while quaternized adsorbent SS-MPTS-VPQ could not. The adsorbent SS-MPTS-VIMH belongs to weak anion exchange adsorbent and SS-MPTS-VPQ belongs to strong anion exchange adsorbent. This study paves a way to the synthesis and application of a novel silica base adsorbents for Re (VII). Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Recovery of uranium by CFBA using a granular organic adsorbent

    International Nuclear Information System (INIS)

    Nakamura, Susumu; Oguma, Kouji; Ito, Yoshiro.

    1995-01-01

    Recovery of uranium from natural seawater by a circulating fluidized-bed adsorber (CFBA) was carried out using an organic adsorbent-a granular amidoxime resin (AOR). In the adsorption experiments, stability of the circulating fluidized state of adsorbent and uranium uptake were measured as a function of adsorption time. Results were compared with those obtained for a typical inorganic adsorbent-hydrous titanium oxide granulated with polyacrylonitrile (PAN-HTO). The circulating fluidized state of AOR was very stable. The total amount of carried-over adsorbent was small enough for an adsorption period of 216 hours. The uranium adsorption rates of AOR increased linearly up to the adsorption time of 100 hours, but the increase rate decreased slightly after this time. The uranium amount adsorbed per unit weight of AOR was larger than that of PAN-HTO. The effect of contacting section height of the CFBA on the uranium uptake was also discussed. (author)

  17. Extraction of uranium from seawater using magnetic adsorbents

    International Nuclear Information System (INIS)

    Yamashita, H.; Fujita, K.; Nakajima, F.; Ozawa, Y.; Murata, T.

    1981-01-01

    A new process for the extraction of uranium from seawater was developed. In the process, uranium adsorption is effected using powdered magnetic adsorbents; the adsorbents are then separated from seawater using magnetic separation technology. This process is superior to a column method using a granulated hydrous titanium oxide adsorber bed in the following ways: (1) a higher rate of adsorption is realized because smaller particles are used in the uranium adsorption; and (2) blocking, which is inevitable in an adsorber bed, is eliminated. The composite hydrous titanium-iron oxide as a magnetic adsorbent having high uranium adsorption capacity and magnetization can be prepared by adding urea to a mixed solution of titanium sulfate and ferrous sulfate. Adsorption and desoprtion of uranium and the removal of the adsorbent using a small-scale uranium extraction plant (about 15 m 3 /d) is reported, and the feasibility of uranium extraction from seawater by this process is demonstrated. 10 figures

  18. XPS and XAS investigation of condensed and adsorbed n-octane on a Cu(110) surface

    International Nuclear Information System (INIS)

    Weiss, K.; Oestroem, H.; Triguero, L.; Ogasawara, H.; Garnier, M.G.; Pettersson, L.G.M.; Nilsson, A.

    2003-01-01

    The electronic structure of n-octane adsorbed on Cu(110) is studied by using X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) in combination with cluster model calculations in the framework of density functional theory (DFT). The molecule is found to be well oriented on the surface, which is seen from the high degree of XAS dichroism. Saturated hydrocarbons are commonly considered to physisorb on metals such as Cu(110), but still the C 1s XAS spectra reveal large changes in the electronic structure of the adsorbed octane relative to the free molecule. We find that the XAS resonances corresponding to the molecular Rydberg-valence states are strongly quenched upon adsorption and that there is a significant hybridization of the molecular valence orbitals with the metal bands. In addition to a precise interpretation of the XAS spectra, we present details on the molecular orbital structure of the adsorbed octane molecule. We also discuss shifts in the relative binding energies of the chemically inequivalent carbon atoms in octane upon adsorption, which lead to a narrower XPS spectrum for the adsorbate than the condensed phase spectrum due to the existence of a new relaxation channel

  19. Study on development of adsorbent of acetaldehyde; Acetaldehyde yo kyuchakuzai no kaihatsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Noda, T. [Nippon Steel Corp., Tokyo (Japan); Suzuki, M. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science

    1997-07-10

    The adsorption of acetaldehyde by porous ceramics impregnated with hydrazinium aluminum sulfate (HAS) is studied. Silicagel, activated alumina, activated clay, and activated carbon are compared, and it is found that silicagel and activated clay are suitable as a substrate for HAS impregnated adsorbent. The adsorption mechanism of acetaldehyde by the adsorbent is believed to be one in which acetaldehyde reacts with hydrazinium and yields acetaldazine. The adsorption capacity of the adsorbent at low acetaldehyde concentration of 0.1 ppm was as large as 1.36 mol/kg. This adsorption capacity at 0.1 ppm acetaldehyde concentration is remarkably larger than that of conventional activated carbon. Hydrazinium decomposes easily in the air because it is a strong reducing agent and reacts with oxygen or carbon dioxide. But hydrazinium impregnated on porous ceramics with HAS becomes more stable and maintains reactivity with acetaldehyde for longer than six months. An adsorbent made of porous ceramics impregnated with HAS is useful as a deodorant for acetaldehyde. 8 refs., 6 figs., 6 tabs.

  20. REMOVAL OF REACTIVE DYES FROM WASTEWATER OF TEXTILE INDUSTRIES BY USING ENVIRONMENTAL FRIENDLY ADSORBENTS

    Directory of Open Access Journals (Sweden)

    ALAM Md Shamim

    2016-05-01

    Full Text Available This paper is aimed at developing a method to treat wastewater by using inexpensive adsorbents. Textile industries produce wastewater, otherwise known as effluent, as a bi-product of their production. The effluent contains several pollutants. Among the various stages of textile production, the operations in the dyeing plant, which include pre-treatments, dyeing, printing and finishing, produce the most pollution. The textile dyeing wastes contain unused or partially used organic compounds, and high level of different pollutants. They are often of strong color and may also be of high temperature. When disposed into water bodies or onto land these effluents will result in the deterioration of ecology and damage to aquatic life. Furthermore they may cause damage to fisheries and economic loss to fishermen and farmer, there may be impacts on human health which can be removed with the help of an effluent treatment plant (ETP. The “clean” water can then be safely discharged into the environment and ultimately save our environment from pollution. In this study, rice husk and cotton dust were used as an adsorbent. In this research work waste water was characterized with this useless adsorbents. The parameters which were tested in this study are DO, BOD, COD, TS, TDS and TSS. The results showed that the selected bio adsorbents have good potential for removal of reactive dyes from textile effluent.

  1. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    International Nuclear Information System (INIS)

    Tsouris, Costas; Mayes, Richard T.; Janke, Christopher James; Dai, Sheng; Das, S.; Liao, W.P.; Kuo, Li-Jung; Wood, Jordana; Gill, Gary; Byers, Maggie Flicker; Schneider, Eric

    2015-01-01

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  2. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Janke, Christopher James [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dai, Sheng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liao, W. -P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wood, Jordana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Byers, Maggie Flicker [Univ. of Texas, Austin, TX (United States); Schneider, Eric [Univ. of Texas, Austin, TX (United States)

    2015-09-30

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  3. Anisotropic elliptic PDEs for feature classification.

    Science.gov (United States)

    Wang, Shengfa; Hou, Tingbo; Li, Shuai; Su, Zhixun; Qin, Hong

    2013-10-01

    The extraction and classification of multitype (point, curve, patch) features on manifolds are extremely challenging, due to the lack of rigorous definition for diverse feature forms. This paper seeks a novel solution of multitype features in a mathematically rigorous way and proposes an efficient method for feature classification on manifolds. We tackle this challenge by exploring a quasi-harmonic field (QHF) generated by elliptic PDEs, which is the stable state of heat diffusion governed by anisotropic diffusion tensor. Diffusion tensor locally encodes shape geometry and controls velocity and direction of the diffusion process. The global QHF weaves points into smooth regions separated by ridges and has superior performance in combating noise/holes. Our method's originality is highlighted by the integration of locally defined diffusion tensor and globally defined elliptic PDEs in an anisotropic manner. At the computational front, the heat diffusion PDE becomes a linear system with Dirichlet condition at heat sources (called seeds). Our new algorithms afford automatic seed selection, enhanced by a fast update procedure in a high-dimensional space. By employing diffusion probability, our method can handle both manufactured parts and organic objects. Various experiments demonstrate the flexibility and high performance of our method.

  4. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials.

    Science.gov (United States)

    Dierking, Ingo; Al-Zangana, Shakhawan

    2017-10-01

    Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i) addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii) novel functionalities can be added to the liquid crystal; and (iii) the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide.

  5. The Effective Coherence Length in Anisotropic Superconductors

    International Nuclear Information System (INIS)

    Polturak, E.; Koren, G.; Nesher, O

    1999-01-01

    If electrons are transmitted from a normal conductor(N) into a superconductor(S), common wisdom has it that the electrons are converted into Cooper pairs within a coherence length from the interface. This is true in conventional superconductors with an isotropic order parameter. We have established experimentally that the situation is rather different in high Tc superconductors having an anisotropic order parameter. We used epitaxial thin film S/N bilayers having different interface orientations in order to inject carriers from S into N along different directions. The distance to which these carriers penetrate were determined through their effect on the Tc of the bilayers. We found that the effective coherence length is 20A only along the a or b directions, while in other directions we find a length of 250dr20A out of plane, and an even larger value for in-plane, off high symmetry directions. These observations can be explained using the Blonder-Tinkham-Klapwijk model adapted to anisotropic superconductivity. Several implications of our results on outstanding problems with high Tc junctions will be discussed

  6. Finite-difference schemes for anisotropic diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Es, Bram van, E-mail: es@cwi.nl [Centrum Wiskunde and Informatica, P.O. Box 94079, 1090GB Amsterdam (Netherlands); FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM (Netherlands); Koren, Barry [Eindhoven University of Technology (Netherlands); Blank, Hugo J. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM (Netherlands)

    2014-09-01

    In fusion plasmas diffusion tensors are extremely anisotropic due to the high temperature and large magnetic field strength. This causes diffusion, heat conduction, and viscous momentum loss, to effectively be aligned with the magnetic field lines. This alignment leads to different values for the respective diffusive coefficients in the magnetic field direction and in the perpendicular direction, to the extent that heat diffusion coefficients can be up to 10{sup 12} times larger in the parallel direction than in the perpendicular direction. This anisotropy puts stringent requirements on the numerical methods used to approximate the MHD-equations since any misalignment of the grid may cause the perpendicular diffusion to be polluted by the numerical error in approximating the parallel diffusion. Currently the common approach is to apply magnetic field-aligned coordinates, an approach that automatically takes care of the directionality of the diffusive coefficients. This approach runs into problems at x-points and at points where there is magnetic re-connection, since this causes local non-alignment. It is therefore useful to consider numerical schemes that are tolerant to the misalignment of the grid with the magnetic field lines, both to improve existing methods and to help open the possibility of applying regular non-aligned grids. To investigate this, in this paper several discretization schemes are developed and applied to the anisotropic heat diffusion equation on a non-aligned grid.

  7. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

    Directory of Open Access Journals (Sweden)

    Ingo Dierking

    2017-10-01

    Full Text Available Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii novel functionalities can be added to the liquid crystal; and (iii the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide.

  8. Quantum electrodynamics of inhomogeneous anisotropic media

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Adrian E.R.; Lombardo, Fernando C. [Ciudad Universitaria, Departamento de Fisica Juan Jose Giambiagi, Buenos Aires (Argentina); IFIBA CONICET-UBA, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2015-02-01

    In this work we calculate the closed time path generating functional for the electromagnetic (EM) field interacting with inhomogeneous anisotropic matter. For this purpose, we first find a general expression for the electromagnetic field's influence action from the interaction of the field with a composite environment consisting in the quantum polarization degrees of freedom in each point of space, at arbitrary temperatures, connected to thermal baths. Then we evaluate the generating functional for the gauge field, in the temporal gauge, by implementing the Faddeev-Popov procedure. Finally, through the point-splitting technique, we calculate closed expressions for the energy, the Poynting vector, and the Maxwell tensor in terms of the Hadamard propagator. We show that all the quantities have contributions from the field's initial conditions and also from the matter degrees of freedom. Throughout the whole work we discuss how the gauge invariance must be treated in the formalism when the EM-field is interacting with inhomogeneous anisotropic matter. We study the electrodynamics in the temporal gauge, obtaining the EM-field's equation and a residual condition. Finally we analyze the case of the EM-field in bulk material and also discuss several general implications of our results in relation with the Casimir physics in a non-equilibrium scenario. (orig.)

  9. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

    Science.gov (United States)

    Dierking, Ingo

    2017-01-01

    Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i) addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii) novel functionalities can be added to the liquid crystal; and (iii) the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide. PMID:28974025

  10. Elastic Modes of an Anisotropic Ridge Waveguide

    Directory of Open Access Journals (Sweden)

    Ameya Galinde

    2012-01-01

    Full Text Available A semi-analytical method for finding the elastic modes propagating along the edge of an anisotropic semi-infinite plate is presented. Solutions are constructed as linear combinations of a finite number of the corresponding infinite plate modes with the constraint that they decay in the direction perpendicular to the edge and collectively satisfy the free boundary condition over the edge surface. Such modes that are confined to the edge can be used to approximate solutions of acoustic ridge waveguides whose supporting structures are sufficiently far away from the free edge. The semi-infinite plate or ridge is allowed to be oriented arbitrarily in the anisotropic crystal. Modifications to the theory to find symmetric and antisymmetric solutions for special crystal orientations are also presented. Accuracy of the solutions can be improved by including more plate modes in the series. Numerical techniques to find modal dispersion relations and orientation dependent modal behavior, are discussed. Results for ridges etched in single crystal Silicon are found to be in good agreement with Finite Element simulations. It is found that variations in modal phase velocity with respect to crystal orientation are not significant, suggesting that anisotropy may not be a critical issue while designing ridge waveguides in Silicon.

  11. Electrically Anisotropic Layered Perovskite Single Crystal

    KAUST Repository

    Li, Ting-You

    2016-04-01

    Organic-inorganic hybrid perovskites (OIHPs), which are promising materials for electronic and optoelectronic applications (1-10), have made into layered organic-inorganic hybrid perovskites (LOIHPs). These LOIHPs have been applied to thin-film transistors, solar cells and tunable wavelength phosphors (11-18). It is known that devices fabricated with single crystal exhibit the superior performance, which makes the growth of large-sized single crystals critical for future device applications (19-23). However, the difficulty in growing large-sized LOIHPs single crystal with superior electrical properties limits their practical applications. Here, we report a method to grow the centimeter-scaled LOIHP single crystal of [(HOC2H4NH3)2PbI4], demonstrating the potentials in mass production. After that, we reveal anisotropic electrical and optoelectronic properties which proved the carrier propagating along inorganic framework. The carrier mobility of in-inorganic-plane (in-plane) devices shows the average value of 45 cm2 V–1 s–1 which is about 100 times greater than the record of LOIHP devices (15), showing the importance of single crystal in device application. Moreover, the LOIHP single crystals show its ultra-short carrier lifetime of 42.7 ps and photoluminescence quantum efficiency (PLQE) of 25.4 %. We expect this report to be a start of LOIHPs for advanced applications in which the anisotropic properties are needed (24-25), and meets the demand of high-speed applications and fast-response applications.

  12. Anisotropic dark energy and CMB anomalies

    International Nuclear Information System (INIS)

    Battye, Richard; Moss, Adam

    2009-01-01

    We investigate the breaking of global statistical isotropy caused by a dark energy component with an energy-momentum tensor which has point symmetry, that could represent a cubic or hexagonal crystalline lattice. In such models Gaussian, adiabatic initial conditions created during inflation can lead to anisotropies in the cosmic microwave background whose spherical harmonic coefficients are correlated, contrary to the standard assumption. We develop an adaptation of the line of sight integration method that can be applied to models where the background energy-momentum tensor is isotropic, but whose linearized perturbations are anisotropic. We then show how this can be applied to the cases of cubic and hexagonal symmetry. We compute quantities which show that such models are indistinguishable from isotropic models even in the most extreme parameter choices, in stark contrast to models with anisotropic initial conditions based on inflation. The reason for this is that the dark energy based models contribute to the CMB anisotropy via the integrated Sachs-Wolfe effect, which is only relevant when the dark energy is dominant, that is, on the very largest scales. For inflationary models, however, the anisotropy is present on all scales.

  13. Relativistic model for anisotropic strange stars

    Science.gov (United States)

    Deb, Debabrata; Chowdhury, Sourav Roy; Ray, Saibal; Rahaman, Farook; Guha, B. K.

    2017-12-01

    In this article, we attempt to find a singularity free solution of Einstein's field equations for compact stellar objects, precisely strange (quark) stars, considering Schwarzschild metric as the exterior spacetime. To this end, we consider that the stellar object is spherically symmetric, static and anisotropic in nature and follows the density profile given by Mak and Harko (2002) , which satisfies all the physical conditions. To investigate different properties of the ultra-dense strange stars we have employed the MIT bag model for the quark matter. Our investigation displays an interesting feature that the anisotropy of compact stars increases with the radial coordinate and attains its maximum value at the surface which seems an inherent property for the singularity free anisotropic compact stellar objects. In this connection we also perform several tests for physical features of the proposed model and show that these are reasonably acceptable within certain range. Further, we find that the model is consistent with the energy conditions and the compact stellar structure is stable with the validity of the TOV equation and Herrera cracking concept. For the masses below the maximum mass point in mass vs radius curve the typical behavior achieved within the framework of general relativity. We have calculated the maximum mass and radius of the strange stars for the three finite values of bag constant Bg.

  14. Building an Anisotropic Meniscus with Zonal Variations

    Science.gov (United States)

    Higashioka, Michael M.; Chen, Justin A.; Hu, Jerry C.

    2014-01-01

    Toward addressing the difficult problems of knee meniscus regeneration, a self-assembling process has been used to re-create the native morphology and matrix properties. A significant problem in such attempts is the recapitulation of the distinct zones of the meniscus, the inner, more cartilaginous and the outer, more fibrocartilaginous zones. In this study, an anisotropic and zonally variant meniscus was produced by self-assembly of the inner meniscus (100% chondrocytes) followed by cell seeding the outer meniscus (coculture of chondrocytes and meniscus cells). After 4 weeks in culture, the engineered, inner meniscus exhibited a 42% increase in both instantaneous and relaxation moduli and a 62% increase in GAG/DW, as compared to the outer meniscus. In contrast, the circumferential tensile modulus and collagen/DW of the outer zone was 101% and 129% higher, respectively, than the values measured for the inner zone. Furthermore, there was no difference in the radial tensile modulus between the control and zonal engineered menisci, suggesting that the inner and outer zones of the engineered zonal menisci successfully integrated. These data demonstrate that not only can biomechanical and biochemical properties be engineered to differ by the zone, but they can also recapitulate the anisotropic behavior of the knee meniscus. PMID:23931258

  15. WGS-Adsorbent Reaction Studies at Laboratory Scale

    International Nuclear Information System (INIS)

    Marano, M.; Torreiro, Y.

    2014-01-01

    This document reports the most significant results obtained during the experimental work performed under task WGS adsorbent experimental studies within CAPHIGAS project (National Research Plan 2008-2011, ref: ENE2009-08002). The behavior of the binary adsorbent-catalyst system which will be used in the hybrid system is described in this document. Main results reported here were used during the design and development of the hybrid system adsorbent catalyst- membrane proposed in the CAPHIGAS project. The influence of main operating parameters and the optimized volume ratio adsorbent-catalyst are also presented in this report. (Author)

  16. Neutralization of Rubidium Adsorbate Electric Fields by Electron Attachment

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacek, J. A. [Univ. of Oklahoma, Norman, OK (United States); Kim, E. [Univ. of Nevada, Las Vegas, NV (United States); Rittenhouse, S. T. [Western Washington Univ., Bellingham, WA (United States); US Naval Academy, Annapolis, MD (United States); Weck, Philippe F [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sadeghpour, H. R. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Shaffer, J. P. [Univ. of Oklahoma, Norman, OK (United States)

    2015-10-01

    We investigate the (0001) surface of single crystal quartz with a submonolayer of Rb adsorbates. Using Rydberg atom electromagnetically induced transparency, we investigate the electric elds resulting from Rb adsorbed on the quartz surface, and measure the activation energy of the Rb adsorbates. We show that the Rb induces a negative electron affnity (NEA) on the quartz surface. The NEA surface allows for low energy electrons to bind to the surface and cancel the electric eld from the Rb adsorbates. Our results have implications for integrating Rydberg atoms into hybrid quantum systems and the fundamental study of atom-surface interactions, as well as applications for electrons bound to a 2D surface.

  17. Anisotropic cosmological models and generalized scalar tensor theory

    Indian Academy of Sciences (India)

    physics pp. 669–673. Anisotropic cosmological models and generalized scalar tensor theory. SUBENOY CHAKRABORTY1,*, BATUL CHANDRA SANTRA2 and ... Anisotropic cosmological models; general scalar tensor theory; inflation. PACS Nos 98.80.Hw; 04.50.+h; 98.80.Cq. 1. Introduction. Brans–Dicke theory [1] (BD ...

  18. Anisotropic static solutions in modelling highly compact bodies

    Indian Academy of Sciences (India)

    Einstein field equations for static anisotropic spheres are solved and exact interior solutions obtained. This paper extends earlier treatments to include anisotropic models which accommodate a wider variety of physically viable energy densities. Two classes of solutions are possible. The first class contains the limiting case ...

  19. Wave velocities in a pre-stressed anisotropic elastic medium

    Indian Academy of Sciences (India)

    Wave velocities in a pre-stressed anisotropic elastic medium. M D Sharma ... Modified Christoffel equations are derived for three-dimensional wave propagation in a general anisotropic medium under initial stress.The three roots of a ... Department of Mathematics, Kurukshetra University, Kurukshetra 136 119, India. UIET ...

  20. Orthonormal bases for anisotropic α-modulation spaces

    DEFF Research Database (Denmark)

    Rasmussen, Kenneth Niemann

    In this article we construct orthonormal bases for bi-variate anisotropic α-modulation spaces. The construction is based on generating a nice anisotropic α-covering and using carefully selected tensor products of univariate brushlet functions with regards to this covering. As an application, we s...

  1. Wave propagation in a general anisotropic poroelastic medium ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 116; Issue 4. Wave propagation in a general anisotropic poroelastic medium: Biot's theories and homogenisation theory. M D Sharma. Volume 116 Issue 4 August ... Keywords. Anisotropic poroelastic (APE) solid; Biot's theory; homogenisation theory; phase velocity.

  2. Modeling and Measurements of CMUTs with Square Anisotropic Plates

    DEFF Research Database (Denmark)

    la Cour, Mette Funding; Christiansen, Thomas Lehrmann; Dahl-Petersen, Christian

    2013-01-01

    The conventional method of modeling CMUTs use the isotropic plate equation to calculate the deflection, leading to deviations from FEM simulations including anisotropic effects of around 10% in center deflection. In this paper, the deflection is found for square plates using the full anisotropic ...

  3. Anisotropic Flow Measurements in ALICE at the Large Hadron Collider

    NARCIS (Netherlands)

    Bilandzic, A.

    2012-01-01

    Anisotropic flow is one of the observables which is sensitive to the properties of the created hot and dense system in heavy-ion collisions. In noncentral heavy-ion collisions the initial volume of the interacting system is anisotropic in coordinate space. Due to multiple interactions this anisotropy

  4. Existence of longitudinal waves in pre-stressed anisotropic elastic ...

    Indian Academy of Sciences (India)

    In a pre-stressed anisotropic elastic medium, three types of quasi-waves propagate along an arbi- trary direction. In general, none of the waves is truly longitudinal. The present study finds the specific directions in a pre-stressed anisotropic elastic medium along which longitudinal waves may propagate. This paper ...

  5. On the origins of the anisotropic mechanical behaviour of extruded ...

    Indian Academy of Sciences (India)

    This paper presents some experimental investigations about the origins of the anisotropic behaviour in cyclic loadings of ... In the second step, microstructural investigations were performed in order to understand the origins of the anisotropic ..... [20] Djebli A, Aid A, Bendouba M, Amrouche A, Benguediab M and Benseddiq ...

  6. Orthonormal bases for anisotropic α-modulation spaces

    DEFF Research Database (Denmark)

    Rasmussen, Kenneth Niemann

    2012-01-01

    In this article we construct orthonormal bases for bi-variate anisotropic α-modulation spaces. The construction is based on generating a nice anisotropic α-covering and using carefully selected tensor products of univariate brushlet functions with regards to this covering. As an application, we s...

  7. Two-Dimensional Superfluidity of Exciton Polaritons Requires Strong Anisotropy

    Directory of Open Access Journals (Sweden)

    Ehud Altman

    2015-02-01

    Full Text Available Fluids of exciton polaritons, excitations of two-dimensional quantum wells in optical cavities, show collective phenomena akin to Bose condensation. However, a fundamental difference from standard condensates stems from the finite lifetime of these excitations, which necessitates continuous driving to maintain a steady state. A basic question is whether a two-dimensional condensate with long-range algebraic correlations can exist under these nonequilibrium conditions. Here, we show that such driven two-dimensional Bose systems cannot exhibit algebraic superfluid order except in low-symmetry, strongly anisotropic systems. Our result implies, in particular, that recent apparent evidence for Bose condensation of exciton polaritons must be an intermediate-scale crossover phenomenon, while the true long-distance correlations fall off exponentially. We obtain these results through a mapping of the long-wavelength condensate dynamics onto the anisotropic Kardar-Parisi-Zhang equation.

  8. Theoretical insight of physical adsorption for a single-component adsorbent+adsorbate system: I. Thermodynamic property surfaces.

    Science.gov (United States)

    Chakraborty, Anutosh; Saha, Bidyut Baran; Ng, Kim Choon; Koyama, Shigeru; Srinivasan, Kandadai

    2009-02-17

    Thermodynamic property surfaces for a single-component adsorbent+adsorbate system are derived and developed from the viewpoint of classical thermodynamics, thermodynamic requirements of chemical equilibrium, Gibbs law, and Maxwell relations. They enable us to compute the entropy and enthalpy of the adsorbed phase, the isosteric heat of adsorption, specific heat capacity, and the adsorbed phase volume thoroughly. These equations are very simple and easy to handle for calculating the energetic performances of any adsorption system. We have shown here that the derived thermodynamic formulations fill up the information gap with respect to the state of adsorbed phase to dispel the confusion as to what is the actual state of the adsorbed phase. We have also discussed and established the temperature-entropy diagrams of (i) CaCl2-in-silica gel+water system for cooling applications, and (ii) activated carbon (Maxsorb III)+methane system for gas storage.

  9. Theoretical Insight of Physical Adsorption for a Single-Component Adsorbent + Adsorbate System: I. Thermodynamic Property Surfaces

    KAUST Repository

    Chakraborty, Anutosh

    2009-02-17

    Thermodynamic property surfaces for a single-component adsorbent + adsorbate system are derived and developed from the viewpoint of classical thermodynamics, thermodynamic requirements of chemical equilibrium, Gibbs law, and Maxwell relations. They enable us to compute the entropy and enthalpy of the adsorbed phase, the isosteric heat of adsorption, specific heat capacity, and the adsorbed phase volume thoroughly. These equations are very simple and easy to handle for calculating the energetic performances of any adsorption system. We have shown here that the derived thermodynamic formulations fill up the information gap with respect to the state of adsorbed phase to dispel the confusion as to what is the actual state of the adsorbed phase. We have also discussed and established the temperature-entropy diagrams of (i) CaCl 2-in-silica gel + water system for cooling applications, and (ii) activated carbon (Maxsorb III) + methane system for gas storage. © Copyright 2009 American Chemical Society.

  10. Critical frontier of anisotropic planar Potts ferromagnets : a new conjucture

    International Nuclear Information System (INIS)

    Tsallis, C.

    1982-01-01

    The critical frontier of the nearest-neighbour q-state Potts ferromagnet in the fully anisotropic 3-12 lattice is conjectured through a star-triangle transformation. It recovers all the available exact results concerning particular cases, namely: (i) anisotropic square lattice for all q; (ii) anisotropic triangular and honeycomb lattices for all q; (iii) anisotropic Kagome and diced lattices for q=2; (iv) isotropic 3-12 and Asanoha lattices for q=2. It provides proposals for several other planar lattices, in particular for the anisotropic Kagome (and diced) one for q different 2, where it slightly differs from the Wu 1979 conjecture (Which also satisfies the cases (i) and (iii)). The bond percolation critical probabilities on the 3-12 and Kagome lattices are determined to be respectively p sub(c) = 0.739830... and p sub(c) = 0.522372.... (Author) [pt

  11. Carbon Dioxide Capture Adsorbents: Chemistry and Methods.

    Science.gov (United States)

    Patel, Hasmukh A; Byun, Jeehye; Yavuz, Cafer T

    2017-04-10

    Excess carbon dioxide (CO 2 ) emissions and their inevitable consequences continue to stimulate hard debate and awareness in both academic and public spaces, despite the widespread lack of understanding on what really is needed to capture and store the unwanted CO 2 . Of the entire carbon capture and storage (CCS) operation, capture is the most costly process, consisting of nearly 70 % of the price tag. In this tutorial review, CO 2 capture science and technology based on adsorbents are described and evaluated in the context of chemistry and methods, after briefly introducing the current status of CO 2 emissions. An effective sorbent design is suggested, whereby six checkpoints are expected to be met: cost, capacity, selectivity, stability, recyclability, and fast kinetics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Applications of core level spectroscopy to adsorbates

    International Nuclear Information System (INIS)

    Nilsson, Anders

    2002-01-01

    In the following review different applications of core-level spectroscopy to atomic and molecular adsorbates will be shown. Core-holes are created through core-level ionization and X-ray absorption processes and the core-hole decays by radiant and non-radiant processes. This forms the basis for X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, Auger electron spectroscopy and X-ray emission spectroscopy. We will demonstrate how we can use the different methods to obtain information about the chemical state, local geometric structure, nature of chemical bonding and dynamics in electron transfer processes. The adsorption of N 2 and CO on Ni(100) will be used as prototype systems for chemisorption while N 2 on graphite and Ar on Pt for physisorption

  13. Selective lanthanide sorption and mechanism using novel hybrid Lewis base (N-methyl-N-phenyl-1,10-phenanthroline-2-carboxamide) ligand modified adsorbent

    International Nuclear Information System (INIS)

    Awual, Md. Rabiul; Kobayashi, Tohru; Miyazaki, Yuji; Motokawa, Ryuhei; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro; Yaita, Tsuyoshi

    2013-01-01

    Highlights: •Hybrid Lewis base adsorbent was prepared for selective lanthanide (Eu, Sm) removal. •Common ions did not interfere due to strong interactions between Eu/Sm and adsorbent. •The adsorbent has good sorption and kinetic performances for potential applications. •The adsorption is reversible and adsorbent reusable in many cycles without any deterioration. -- Abstract: This study aims to develop a highly selective Lewis base adsorbent to investigate the selective sorption and recovery of Eu(III) and Sm(III) from wastewater. The oxygen and nitrogen donor atoms containing Lewis base N-methyl-N-phenyl-1,10-phenanthroline-2-carboxamide (MePhPTA) ligand was synthesized and subsequently an adsorbent was prepared by direct immobilization onto mesoporous silica. Determined maximum adsorption capacities were 125.63 and 124.38 mg/g for Eu(III) and Sm(III), respectively. Experiments with mixed-cations solutions showed that the sequence of preferential adsorption was Eu(III) > Sm(III). The lanthanide sorption by hybrid Lewis base adsorbent (HyLBA) was not adversely affected by the presence of sodium, potassium, calcium, magnesium, chloride, sulfate and nitrate ions due to strong affinity between hard Lewis acid lanthanide and hard Lewis base adsorbent. The crystallography for the Sm-MePhPTA complex suggested that MePhPTA was strongly coordinated to Sm(III) with oxygen and nitrogen by forming a stable complex with two 5-membered rings. The data clarified that bond lengths between Sm(III) and amide oxygen (2.475 Å) were shorter than Sm-N (2.662 Å) in phenanthroline moiety indicating strong oxygen driven HyLBA. The results suggested that HyLBA has a good prospect of promising applications for separation/sorption of lanthanide ions from effluents

  14. Organic adsorbates on metal surfaces. PTCDA and NTCDA on AG(110)

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Afshin

    2010-02-22

    , the inclusion of the major part of the attractive van-der-Waals interaction brings the adsorbate back to an arrangement close to parallel to the substrate, with very small differences in height between the different subunits. With respect to experimental data obtained on Ag(111), the calculated distance between adsorbate and substrate is somewhat smaller, indicating that the open Ag(110) surface interacts more strongly with the organic compounds. This is consistent with the fact that only Ag(110) induces a brickwall unit cell of the adsorbate, a clear sign for a particularly large adsorption energy. The resulting model geometries are analysed in terms of cohesive energy, Mulliken charges, core level shifts, and vibrational properties. (orig.)

  15. Experimental evidence for anisotropic double exchange interaction driven anisotropic transport in manganite heterostructures

    NARCIS (Netherlands)

    Liao, Zhaoliang; Koster, Gertjan; Huijben, Mark; Rijnders, A.J.H.M.

    2017-01-01

    An anisotropic double exchange interaction driven giant transport anisotropy is demonstrated in a canonic double exchange system of La2/3Sr1/3MnO3 ultrathin films epitaxially grown on NdGaO3 (110) substrates. The oxygen octahedral coupling at the La2/3Sr1/3MnO3/NdGaO3 interface induces a planar

  16. Quantum correlation dynamics subjected to critical spin environment with short-range anisotropic interaction.

    Science.gov (United States)

    Guo, J L; Zhang, X Z

    2016-09-06

    Short-range interaction among the spins can not only results in the rich phase diagram but also brings about fascinating phenomenon both in the contexts of quantum computing and information. In this paper, we investigate the quantum correlation of the system coupled to a surrounding environment with short-range anisotropic interaction. It is shown that the decay of quantum correlation of the central spins measured by pairwise entanglement and quantum discord can serve as a signature of quantum phase transition. In addition, we study the decoherence factor of the system when the environment is in the vicinity of the phase transition point. In the strong coupling regime, the decay of the decoherence factor exhibits Gaussian envelop in the time domain. However, in weak coupling limit, the quantum correlation of the system is robust against the disturbance of the magnetic field through optimal control of the anisotropic short-range interaction strength. Based on this, the effects of the short-range anisotropic interaction on the sudden transition from classical to quantum decoherence are also presented.

  17. Friction and diffusion dynamics of adsorbates at surfaces

    NARCIS (Netherlands)

    Fusco, C.

    2005-01-01

    A theoretical study of the motion of adsorbates (e. g. atoms, molecules or clusters) on solid surfaces is presented, with a focus on surface diffusion and atomic-scale friction. These two phenomena are inextricably linked, because when an atomic or molecular adsorbate diffuses, or is pulled, it

  18. Synthesis and properties of porous zeolite aluminosilicate adsorbents

    International Nuclear Information System (INIS)

    Shilina, A.S.; Milinchuk, V.K.; Burukhin, S.B.; Gordienko, A.B.

    2015-01-01

    Environmentally safe non-energy-intensive methods of the synthesis have been developed and the properties of solid inorganic nanostructured zeolite-like adsorbents of a broad spectrum have been studied. The sorption capacities of the adsorbents with respect to various components of water pollution have been determined [ru

  19. Development of ultrafiltration and inorganic adsorbents: January--March 1977

    International Nuclear Information System (INIS)

    Koenst, J.W. Jr.

    1977-01-01

    Ultrafiltration media with and without the assistance of bone char filters were evaluated to determine their effectiveness in removing radionuclides from contaminated solutions. Precipitants, resin, adsorbents, and inorganic adsorbents were studied to determine their effectiveness in decontaminating solutions. A study of the effects of radiation on ultrafiltration media was initiated. An ultrafiltration media pilot plant was ordered and is being installed

  20. Comparative evaluation of selected starches as adsorbent for Thin ...

    African Journals Online (AJOL)

    The most commonly used is silica gel which is an inorganic adsorbent. Organic substances like cellulose, polyethylene are also used. All these are imported into Nigeria and are unhealthy for economic policies. Most commonly used adsorbent may not be easy to produce locally, but starch, which is a very common product, ...

  1. Single bank NOx adsorber for heavy duty diesel engines

    NARCIS (Netherlands)

    Genderen, M. van; Aken, M.G. van

    2003-01-01

    In a NOx adsorber programme the feasibility for applying this technology to heavy duty diesel engines was investigated. After modelling and simulations for realising best λ < 1 engine conditions a platform was build which was used to obtain good NOx adsorber regeneration settings in a number of

  2. Crosslinked xylan as an affinity adsorbent for endo-xylanases.

    NARCIS (Netherlands)

    Rozie, H.; Somers, W.; Bonte, A.; Rombouts, F.M.; Visser, J.

    1992-01-01

    In order to facilitate the purification of xylanases from Aspergillus niger, an affinity adsorbent has been developed from oat spelts xylan. A suitable adsorbent was only obtained by crosslinking oat spelts xylan with epichlorohydrin in water but not in ethanol or ethanol-water mixtures. After some

  3. Anisotropic plasmas from axion and dilaton deformations

    Energy Technology Data Exchange (ETDEWEB)

    Donos, Aristomenis [Centre for Particle Theory and Department of Mathematical Sciences, Durham University,South Rd., Durham (United Kingdom); Gauntlett, Jerome P. [Blackett Laboratory, Imperial College,Prince Consort Rd., London (United Kingdom); Sosa-Rodriguez, Omar [Centre for Particle Theory and Department of Mathematical Sciences, Durham University,South Rd., Durham (United Kingdom)

    2016-11-02

    We construct black hole solutions of type IIB supergravity that are holographically dual to anisotropic plasmas arising from deformations of an infinite class of four-dimensional CFTs. The CFTs are dual to AdS{sub 5}×X{sub 5}, where X{sub 5} is an Einstein manifold, and the deformations involve the type IIB axion and dilaton, with non-trivial periodic dependence on one of the spatial directions of the CFT. At low temperatures the solutions approach smooth domain wall solutions with the same AdS{sub 5}×X{sub 5} solution appearing in the far IR. For sufficiently large deformations an intermediate scaling regime appears which is governed by a Lifshitz-like scaling solution. We calculate the DC thermal conductivity and some components of the shear viscosity tensor.

  4. Analytical study of anisotropic compact star models

    Science.gov (United States)

    Ivanov, B. V.

    2017-11-01

    A simple classification is given of the anisotropic relativistic star models, resembling the one of charged isotropic solutions. On the ground of this database, and taking into account the conditions for physically realistic star models, a method is proposed for generating all such solutions. It is based on the energy density and the radial pressure as seeding functions. Numerous relations between the realistic conditions are found and the need for a graphic proof is reduced just to one pair of inequalities. This general formalism is illustrated with an example of a class of solutions with linear equation of state and simple energy density. It is found that the solutions depend on three free constants and concrete examples are given. Some other popular models are studied with the same method.

  5. Analytical study of anisotropic compact star models

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, B.V. [Bulgarian Academy of Science, Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria)

    2017-11-15

    A simple classification is given of the anisotropic relativistic star models, resembling the one of charged isotropic solutions. On the ground of this database, and taking into account the conditions for physically realistic star models, a method is proposed for generating all such solutions. It is based on the energy density and the radial pressure as seeding functions. Numerous relations between the realistic conditions are found and the need for a graphic proof is reduced just to one pair of inequalities. This general formalism is illustrated with an example of a class of solutions with linear equation of state and simple energy density. It is found that the solutions depend on three free constants and concrete examples are given. Some other popular models are studied with the same method. (orig.)

  6. Fluid flow through anisotropic porous medium

    International Nuclear Information System (INIS)

    Telles, A.S.; Massarani, G.

    1975-01-01

    Darcy's equation represents a simplified form of the equation of motion for the fluid flowing through a porous medium. The simplifications concern the elimination of the acceleration, the divergence of the extra stress terms, and the assumption of existence of a linear form in the velocity for the resistive force the fluid exerts upon the solid. This hypothesis may not be valid for all anisotropic media. In some instances, measurements of directional resistivity suggest existence of the resistivity tensor, leaving entirely open the question of symmetry. In connection with this important question, an experimental scheme for the determination of the antisymmetric part of this tensor is suggested. The conclusion is that material symmetries is the only macroscopic concept that imposes restrictions on the form of the resistivity and extra stress tensors [pt

  7. Long-range interaction of anisotropic systems

    KAUST Repository

    Zhang, Junyi

    2015-02-01

    The first-order electrostatic interaction energy between two far-apart anisotropic atoms depends not only on the distance between them but also on their relative orientation, according to Rayleigh-Schrödinger perturbation theory. Using the first-order interaction energy and the continuum model, we study the long-range interaction between a pair of parallel pristine graphene sheets at zero temperature. The asymptotic form of the obtained potential density, &epsi:(D) &prop: ?D ?3 ?O(D?4), is consistent with the random phase approximation and Lifshitz theory. Accordingly, neglectance of the anisotropy, especially the nonzero first-order interaction energy, is the reason why the widely used Lennard-Jones potential approach and dispersion corrections in density functional theory give a wrong asymptotic form ε(D) &prop: ?D?4. © EPLA, 2015.

  8. Theory of Random Anisotropic Magnetic Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1976-01-01

    A mean-field-crystal-field theory is developed for random, multicomponent, anisotropic magnetic alloys. It is specially applicable to rare-earth alloys. A discussion is given of multicritical points and phase transitions between various states characterized by order parameters with different...... spatial directions or different ordering wave vectors. Theoretical predictions based on known parameters for the phase diagrams and magnetic moments for the binary rare-earth alloys of Tb, Dy, Ho, and Er, Tb-Tm, Nd-Pr, and pure double-hcp Nd agree qualitatively with the experimental observations....... Quantitative agreement can be obtained by increasing the interaction between different alloy elements, in particular for alloys with very different axial anisotropy, e.g., Tb-Tm. A model system consisting of a singlet-singlet and singlet-doublet alloy is discussed in detail. A simple procedure to include...

  9. Patterning of Structurally Anisotropic Composite Hydrogel Sheets.

    Science.gov (United States)

    Prince, Elisabeth; Alizadehgiashi, Moien; Campbell, Melissa; Khuu, Nancy; Albulescu, Alexandra; De France, Kevin; Ratkov, Dimitrije; Li, Yunfeng; Hoare, Todd; Kumacheva, Eugenia

    2018-04-09

    Compositional and structural patterns play a crucial role in the function of many biological tissues. In the present work, for nanofibrillar hydrogels formed by chemically cross-linked cellulose nanocrystals (CNC) and gelatin, we report a microextrusion-based 3D printing method to generate structurally anisotropic hydrogel sheets with CNCs aligned in the direction of extrusion. We prepared hydrogels with a uniform composition, as well as hydrogels with two different types of compositional gradients. In the first type of gradient hydrogel, the composition of the sheet varied parallel to the direction of CNC alignment. In the second hydrogel type, the composition of the sheet changed orthogonally to the direction of CNC alignment. The hydrogels exhibited gradients in structure, mechanical properties, and permeability, all governed by the compositional patterns, as well as cytocompatibility. These hydrogels have promising applications for both fundamental research and for tissue engineering and regenerative medicine.

  10. Silicon as an anisotropic mechanical material

    DEFF Research Database (Denmark)

    Thomsen, Erik Vilain; Reck, Kasper; Skands, Gustav Erik

    2014-01-01

    While silicon is an anisotropic material it is often in literature treated as an isotropic material when it comes to plate calculations. This leads to considerable errors in the calculated deflection. To overcome this problem, we present an in-depth analysis of the bending behavior of thin...... both exact analytical expressions and approximate expressions calculated by the Galerkin method. The results are applied to plates made on silicon (0 0 1), (0 1 1) and (1 1 1) substrates, respectively, and analytical equations for the deflection, strain energy and resonance frequency of such plates...... analytical models involving crystalline plates, such as those often found in the field of micro electro mechanical systems. The effect of elastic boundary conditions is taken into account by using an effective radius of the plate....

  11. Anisotropic dynamic mass density for fluidsolid composites

    KAUST Repository

    Wu, Ying

    2012-10-01

    By taking the low frequency limit of multiple-scattering theory, we obtain the dynamic effective mass density of fluidsolid composites with a two-dimensional rectangular lattice structure. The anisotropic mass density can be described by an angle-dependent dipole solution, to the leading-order of solid concentration. The angular dependence vanishes for the square lattice, but at high solid concentrations there is a structure-dependent factor that contributes to the leading-order solution. In all cases, Woods formula is found to be accurately valid for the effective bulk modulus, independent of the structures. Numerical evaluations from the solutions are shown to be in excellent agreement with finite-element simulations. © 2012 Elsevier B.V.

  12. Spectral functions from anisotropic lattice QCD

    Science.gov (United States)

    Aarts, G.; Allton, C.; Amato, A.; Evans, W.; Giudice, P.; Harris, T.; Kelly, A.; Kim, S. Y.; Lombardo, M. P.; Praki, K.; Ryan, S. M.; Skullerud, J.-I.

    2016-12-01

    The FASTSUM collaboration has been carrying out lattice simulations of QCD for temperatures ranging from one third to twice the crossover temperature, investigating the transition region, as well as the properties of the Quark Gluon Plasma. In this contribution we concentrate on quarkonium correlators and spectral functions. We work in a fixed scale scheme and use anisotropic lattices which help achieving the desirable fine resolution in the temporal direction, thus facilitating the (ill posed) integral transform from imaginary time to frequency space. We contrast and compare results for the correlators obtained with different methods, and different temporal spacings. We observe robust features of the results, confirming the sequential dissociation scenario, but also quantitative differences indicating that the methods' systematic errors are not yet under full control. We briefly outline future steps towards accurate results for the spectral functions and their associated statistical and systematic errors.

  13. Derivation of the optical constants of anisotropic

    Science.gov (United States)

    Aronson, J. R.; Emslie, A. G.; Smith, E. M.; Strong, P. F.

    1985-07-01

    This report concerns the development of methods for obtaining the optical constants of anisotropic crystals of the triclinic and monoclinic systems. The principal method used, classical dispersion theory, is adapted to these crystal systems by extending the Lorentz line parameters to include the angles characterizing the individual resonances, and by replacing the dielectric constant by a dielectric tensor. The sample crystals are gypsium, orthoclase and chalcanthite. The derived optical constants are shown to be suitable for modeling the optical properties of particulate media in the infrared spectral region. For those materials where suitable size single crystals are not available, an extension of a previously used method is applied to alabaster, a polycrystalline material of the monoclinic crystal system.

  14. Anisotropic thermal expansion in flexible materials

    Science.gov (United States)

    Romao, Carl P.

    2017-10-01

    A definition of the Grüneisen parameters for anisotropic materials is derived based on the response of phonon frequencies to uniaxial stress perturbations. This Grüneisen model relates the thermal expansion in a given direction (αi i) to one element of the elastic compliance tensor, which corresponds to the Young's modulus in that direction (Yi i). The model is tested through ab initio prediction of thermal expansion in zinc, graphite, and calcite using density functional perturbation theory, indicating that it could lead to increased accuracy for structurally complex systems. The direct dependence of αi i on Yi i suggests that materials which are flexible along their principal axes but rigid in other directions will generally display both positive and negative thermal expansion.

  15. The Anisotropic Glassy Properties of Decagonal Quasicrystals

    Directory of Open Access Journals (Sweden)

    Dragoş-Victor Anghel

    2013-01-01

    Full Text Available We use an extended version of the standard tunneling model to explain the anisotropic sound absorption in decagonal quasicrystals. The glassy properties are determined by an ensemble of two level systems (TLSs, arbitrarily oriented. The TLS is characterized by a 3 × 3 symmetric tensor, [T], which couples to the strain field, [S], through a 3 × 3 × 3 × 3 tensor of coupling constants, [R]. The structure of [R] reflects the symmetry of the quasicrystal. We also analyze the probability distributions of the elements of [T] in this particular model for a better understanding of the characteristics of “isotropic” and “anisotropic” distributions of the ensemble of TLSs. We observe that the distribution of the elements is neither simple nor intuitive and therefore it is difficult to guess it a priory, using qualitative arguments based on the symmetry properties.

  16. Final fate of charged anisotropic fluid collapse

    Science.gov (United States)

    Khan, Suhail; Shah, Hassan; Ahmad, Zahid; Ramzan, Muhammad

    2017-11-01

    This paper studies the effects of charge on spherically symmetric collapse of anisotropic fluid with a positive cosmological constant. It is observed that electromagnetic field places restriction on the bounds of cosmological constant, which acts as repulsive force against the contraction of matter content and hence the rate of destruction is faster in the presence of electromagnetic field. We have also noted that the presence of charge affects the time interval between the formation of cosmological horizon (CH) and black hole horizon (BHH). When the electric field strength E(t, r) vanishes, our investigations are in full agreement with the results obtained by Ahmad and Malik [Int. J. Theor. Phys. 55, 600 (2016)].

  17. Turbulent Output-Based Anisotropic Adaptation

    Science.gov (United States)

    Park, Michael A.; Carlson, Jan-Renee

    2010-01-01

    Controlling discretization error is a remaining challenge for computational fluid dynamics simulation. Grid adaptation is applied to reduce estimated discretization error in drag or pressure integral output functions. To enable application to high O(10(exp 7)) Reynolds number turbulent flows, a hybrid approach is utilized that freezes the near-wall boundary layer grids and adapts the grid away from the no slip boundaries. The hybrid approach is not applicable to problems with under resolved initial boundary layer grids, but is a powerful technique for problems with important off-body anisotropic features. Supersonic nozzle plume, turbulent flat plate, and shock-boundary layer interaction examples are presented with comparisons to experimental measurements of pressure and velocity. Adapted grids are produced that resolve off-body features in locations that are not known a priori.

  18. Effective stress law for anisotropic elastic deformation

    International Nuclear Information System (INIS)

    Carroll, M.M.

    1979-01-01

    An effective stress law is derived analytically to describe the effect of pore fluid pressure on the linearly elastic response of saturated porous rocks which exhibit anisotropy. For general anisotropy the difference between the effective stress and the applied stress is not hydrostatic. The effective stress law involves two constants for transversely isotropic response and three constants for orthotropic response; these constants can be expressed in terms of the moduli of the porous material and of the solid material. These expressions simplify considerably when the anisotropy is structural rather than intrinsic, i.e., in the case of an isotropic solid material with an anisotropic pore structure. In this case the effective stress law involves the solid or grain bulk modulus and two or three moduli of the porous material, for transverse isotropy and orthotropy, respectively. The law reduces, in the case of isotropic response, to that suggested by Geertsma (1957) and by Skempton (1961) and derived analytically by Nur and Byerlee

  19. A FDM anisotropic formulation for EEG simulation.

    Science.gov (United States)

    Bruno, P; Hyttinen, J; Inchingolo, P; Magrofuoco, A; Mininel, S; Vatta, F

    2006-01-01

    Accurate head modeling is required to properly simulate bioelectric phenomena in 3-D as well as to estimate the 3-D bioelectric activity starting from superficial bioelectric measurements and 3-D imaging. Aiming to build an accurate and realistic representation of the volume conductor of the head, also the anisotropy of head tissues should be taken into account. In this paper we describe a new finite-difference method (FDM) formulation which accounts for anisotropy of the various head tissues. Our proposal, being based on FDM, derives the head model directly from patient's specific clinical images. We present here the details of the numerical formulation and the method validation by comparing our numerical proposal and known analytical results using a multi-shell anisotropic head model with skull anisotropy. Furthermore, we analyzed also different numerical grid refinement and EEG source characteristics. The comparison with previously developed FDM methods shows a good performance of the proposed method.

  20. Anisotropic magnetism in field-structured composites

    International Nuclear Information System (INIS)

    Martin, James E.; Venturini, Eugene; Odinek, Judy; Anderson, Robert A.

    2000-01-01

    Magnetic field-structured composites (FSCs) are made by structuring magnetic particle suspensions in uniaxial or biaxial (e.g., rotating) magnetic fields, while polymerizing the suspending resin. A uniaxial field produces chainlike particle structures, and a biaxial field produces sheetlike particle structures. In either case, these anisotropic structures affect the measured magnetic hysteresis loops, with the magnetic remanence and susceptibility increased significantly along the axis of the structuring field, and decreased slightly orthogonal to the structuring field, relative to the unstructured particle composite. The coercivity is essentially unaffected by structuring. We present data for FSCs of magnetically soft particles, and demonstrate that the altered magnetism can be accounted for by considering the large local fields that occur in FSCs. FSCs of magnetically hard particles show unexpectedly large anisotropies in the remanence, and this is due to the local field effects in combination with the large crystalline anisotropy of this material. (c) 2000 The American Physical Society

  1. An Anisotropic Hardening Model for Springback Prediction

    International Nuclear Information System (INIS)

    Zeng, Danielle; Xia, Z. Cedric

    2005-01-01

    As more Advanced High-Strength Steels (AHSS) are heavily used for automotive body structures and closures panels, accurate springback prediction for these components becomes more challenging because of their rapid hardening characteristics and ability to sustain even higher stresses. In this paper, a modified Mroz hardening model is proposed to capture realistic Bauschinger effect at reverse loading, such as when material passes through die radii or drawbead during sheet metal forming process. This model accounts for material anisotropic yield surface and nonlinear isotropic/kinematic hardening behavior. Material tension/compression test data are used to accurately represent Bauschinger effect. The effectiveness of the model is demonstrated by comparison of numerical and experimental springback results for a DP600 straight U-channel test

  2. Recent developments in anisotropic heterogeneous shell theory

    CERN Document Server

    Grigorenko, Alexander Ya; Grigorenko, Yaroslav M; Vlaikov, Georgii G

    2016-01-01

    This volume focuses on the relevant general theory and presents some first applications, namely those based on classical shell theory. After a brief introduction, during which the history and state-of-the-art are discussed, the first chapter presents the mechanics of anisotropic heterogeneous shells, covering all relevant assumptions and the basic relations of 3D elasticity, classical and refined shell models. The second chapter examines the numerical techniques that are used, namely discrete orthogonalization, spline-collocation and Fourier series, while the third highlights applications based on classical theory, in particular, the stress-strain state of shallow shells, non-circular shells, shells of revolution, and free vibrations of conical shells. The book concludes with a summary and an outlook bridging the gap to the second volume.

  3. Predictions from an anisotropic inflationary era

    International Nuclear Information System (INIS)

    Pitrou, Cyril; Uzan, Jean-Philippe; Pereira, Thiago S

    2008-01-01

    This paper investigates the predictions of an inflationary phase starting from a homogeneous and anisotropic universe of the Bianchi I type. After discussing the evolution of the background spacetime, focusing on the number of e-folds and the isotropization, we solve the perturbation equations and predict the power spectra of the curvature perturbations and gravity waves at the end of inflation. The main features of the early anisotropic phase is (1) a dependence of the spectra on the direction of the modes, (2) a coupling between curvature perturbations and gravity waves and (3) the fact that the two gravity wave polarizations do not share the same spectrum on large scales. All these effects are significant only on large scales and die out on small scales where isotropy is recovered. They depend on a characteristic scale that can, but a priori must not, be tuned to some observable scale. To fix the initial conditions, we propose a procedure that generalizes the one standardly used in inflation but that takes into account the fact that the WKB regime is violated at early times when the shear dominates. We stress that there exist modes that do not satisfy the WKB condition during the shear-dominated regime and for which the amplitude at the end of inflation depends on unknown initial conditions. On such scales, inflation loses its predictability. This study paves the way for the determination of the cosmological signature of a primordial shear, whatever the Bianchi I spacetime. It thus stresses the importance of the WKB regime to draw inflationary predictions and demonstrates that, when the number of e-folds is large enough, the predictions converge toward those of inflation in a Friedmann–Lemaître spacetime but that they are less robust in the case of an inflationary era with a small number of e-folds

  4. Effective orthorhombic anisotropic models for wavefield extrapolation

    KAUST Repository

    Ibanez-Jacome, W.

    2014-07-18

    Wavefield extrapolation in orthorhombic anisotropic media incorporates complicated but realistic models to reproduce wave propagation phenomena in the Earth\\'s subsurface. Compared with the representations used for simpler symmetries, such as transversely isotropic or isotropic, orthorhombic models require an extended and more elaborated formulation that also involves more expensive computational processes. The acoustic assumption yields more efficient description of the orthorhombic wave equation that also provides a simplified representation for the orthorhombic dispersion relation. However, such representation is hampered by the sixth-order nature of the acoustic wave equation, as it also encompasses the contribution of shear waves. To reduce the computational cost of wavefield extrapolation in such media, we generate effective isotropic inhomogeneous models that are capable of reproducing the firstarrival kinematic aspects of the orthorhombic wavefield. First, in order to compute traveltimes in vertical orthorhombic media, we develop a stable, efficient and accurate algorithm based on the fast marching method. The derived orthorhombic acoustic dispersion relation, unlike the isotropic or transversely isotropic ones, is represented by a sixth order polynomial equation with the fastest solution corresponding to outgoing P waves in acoustic media. The effective velocity models are then computed by evaluating the traveltime gradients of the orthorhombic traveltime solution, and using them to explicitly evaluate the corresponding inhomogeneous isotropic velocity field. The inverted effective velocity fields are source dependent and produce equivalent first-arrival kinematic descriptions of wave propagation in orthorhombic media. We extrapolate wavefields in these isotropic effective velocity models using the more efficient isotropic operator, and the results compare well, especially kinematically, with those obtained from the more expensive anisotropic extrapolator.

  5. Distributions of uranium adsorbed from seawater in spherical polyacrylamidoxime chelating resins

    International Nuclear Information System (INIS)

    Katoh, Shunsaku; Sugasaka, Kazuhiko; Hirotsu, Takahiro; Takai, Nobuharu; Itagaki, Takaharu; Ouchi, Hidenaga.

    1984-01-01

    Distributions of metals adsorbed from seawater in spherical polyacrylamidoxime chelating resins were measured by X-ray micro-analyzer. Distributions of uranium in adsorbents were different according to their gel structure or porosity. In the case of adsorbents with low swelling tendencies, uranium was adsorbed only in the superficial layers of the adsorbents. The amount of adsorbed uranium increased with increasing of contact time, but no uranium was detected in the center of adsorbent even after 331 days. Iron was adsorbed only in the surface layer. Magnesium was detected almost uniformly in all parts of adsorbent. Copper and zinc were detected very little. (author)

  6. Processing method and device for iodine adsorbing material

    International Nuclear Information System (INIS)

    Watanabe, Shin-ichi; Shiga, Reiko.

    1997-01-01

    An iodine adsorbing material adsorbing silver compounds is reacted with a reducing gas, so that the silver compounds are converted to metal silver and stored. Then, the silver compounds are not melted or recrystallized even under a highly humid condition, accordingly, peeling of the adsorbed materials from a carrier can be prevented, and the iodine adsorbing material can be stored stably. Since the device is disposed in an off gas line for discharging off gases from a nuclear power facility, the iodine adsorbing material formed by depositing silver halides to the carrier is contained, and a reducing or oxidizing gas is supplied to the vessel as required, and silver halides can be converted to metal silver or the metal silver can be returned to silver halide. (T.M.)

  7. Sequestering nickel (ii) ions from aqueous solutions using various adsorbents

    International Nuclear Information System (INIS)

    Bello, O.S.; Adegoke, K.A.; Bello, O.U.

    2014-01-01

    Adsorption process has proven to be one of the best water treatment technologies around the world and activated carbon is undoubtedly considered as a universal adsorbent for the removal of different types of pollutants from water. However, widespread use of commercial activated carbon is sometimes restricted due to its high cost. Attempts have been made to develop inexpensive adsorbents utilizing numerous agro-industrial and municipal waste materials. Use of agricultural waste materials as low-cost adsorbents is attractive because it reduces the cost of waste disposal, thereby leading to environmental protection. In this review, agricultural, synthetic and other adsorbents used for adsorbing nickel (II) ion from aqueous solutions are reported. Different ways to improve their efficiencies are also discussed. (author)

  8. Noble gas separation with the use of inorganic adsorbents

    International Nuclear Information System (INIS)

    Pence, D.T.; Chou, C.C.; Christian, J.D.; Paplawsky, W.J.

    1979-01-01

    A noble gas separation process is proposed for application to airborne nuclear fuel reprocessing plant effluents. The process involves the use of inorganic adsorbents for the removal of contaminant gases and noble gas separation through selective adsorption. Water and carbon dioxide are removed with selected zeolites that do not appreciably adsorb the noble gases. Xenon is essentially quantitatively removed with a specially developed adsorbent using conventional adsorption-desorption techniques. Oxygen is removed to low ppM levels by the use of a rapid cycle adsorption technique on a special adsorbent leaving a krypton-nitrogen mixture. Krypton is separated from nitrogen with a special adsorbent operated at about -80 0 C. Because the separation process does not require high pressures and oxygen is readily removed to sufficiently limit ozone formation to insignificant levels, appreciable capital and operating cost savings with this process are possible compared with other proposed processes. In addition, the proposed process is safer to operate

  9. Ion and impurity transport in turbulent, anisotropic magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Negrea, M; Petrisor, I [Department of Physics, Association Euratom-MEdC, Romania, University of Craiova, A.I. Cuza str. 13, Craiova (Romania); Isliker, H; Vogiannou, A; Vlahos, L [Section of Astrophysics, Astronomy and Mechanics, Department of Physics, University of Thessaloniki, Association Euratom-Hellenic Republic, 541 24 Thessaloniki (Greece); Weyssow, B [Physique Statistique-Plasmas, Association Euratom-Etat Belge, Universite Libre de Bruxelles, Campus Plaine, Bd. du Triomphe, 1050 Bruxelles (Belgium)

    2011-08-15

    We investigate ion and impurity transport in turbulent, possibly anisotropic, magnetic fields. The turbulent magnetic field is modeled as a correlated stochastic field, with Gaussian distribution function and prescribed spatial auto-correlation function, superimposed onto a strong background field. The (running) diffusion coefficients of ions are determined in the three-dimensional environment, using two alternative methods, the semi-analytical decorrelation trajectory (DCT) method, and test-particle simulations. In a first step, the results of the test-particle simulations are compared with and used to validate the results obtained from the DCT method. For this purpose, a drift approximation was made in slab geometry, and relatively good qualitative agreement between the DCT method and the test-particle simulations was found. In a second step, the ion species He, Be, Ne and W, all assumed to be fully ionized, are considered under ITER-like conditions, and the scaling of their diffusivities is determined with respect to varying levels of turbulence (varying Kubo number), varying degrees of anisotropy of the turbulent structures and atomic number. In a third step, the test-particle simulations are repeated without drift approximation, directly using the Lorentz force, first in slab geometry, in order to assess the finite Larmor radius effects, and second in toroidal geometry, to account for the geometric effects. It is found that both effects are important, most prominently the effects due to toroidal geometry and the diffusivities are overestimated in slab geometry by an order of magnitude.

  10. Black hole in closed spacetime with an anisotropic fluid

    Science.gov (United States)

    Kim, Hyeong-Chan

    2017-09-01

    We study spherically symmetric geometries made of anisotropic perfect fluid based on general relativity. The purpose of this work is to find and classify black hole solutions in closed spacetime. In a general setting, we find that a static and closed space exists only when the radial pressure is negative but its size is smaller than the density. The Einstein equation is eventually cast into a first-order autonomous equation on a two-dimensional plane of scale-invariant variables, which are equivalent to the Tolman-Oppenheimer-Volkoff equation in general relativity. Then, we display various solution curves numerically. An exact solution describing a black hole solution in a closed spacetime was known in [I. Cho and H. C. Kim, Phys. Rev. D 95, 084052 (2017), 10.1103/PhysRevD.95.084052], which bears a naked singularity and negative-energy era. We find that these two deficits can be remedied when ρ +3 p1>0 and ρ +p1+2 p2<0 , where the second violates the strong energy condition.

  11. Anisotropic intrinsic spin Hall effect in quantum wires

    International Nuclear Information System (INIS)

    Cummings, A W; Akis, R; Ferry, D K

    2011-01-01

    We use numerical simulations to investigate the spin Hall effect in quantum wires in the presence of both Rashba and Dresselhaus spin-orbit coupling. We find that the intrinsic spin Hall effect is highly anisotropic with respect to the orientation of the wire, and that the nature of this anisotropy depends strongly on the electron density and the relative strengths of the Rashba and Dresselhaus spin-orbit couplings. In particular, at low densities, when only one subband of the quantum wire is occupied, the spin Hall effect is strongest for electron momentum along the [1-bar 10] axis, which is the opposite of what is expected for the purely 2D case. In addition, when more than one subband is occupied, the strength and anisotropy of the spin Hall effect can vary greatly over relatively small changes in electron density, which makes it difficult to predict which wire orientation will maximize the strength of the spin Hall effect. These results help to illuminate the role of quantum confinement in spin-orbit-coupled systems, and can serve as a guide for future experimental work on the use of quantum wires for spin-Hall-based spintronic applications. (paper)

  12. Lattice refining loop quantum cosmology, anisotropic models, and stability

    International Nuclear Information System (INIS)

    Bojowald, Martin; Cartin, Daniel; Khanna, Gaurav

    2007-01-01

    A general class of loop quantizations for anisotropic models is introduced and discussed, which enhances loop quantum cosmology by relevant features seen in inhomogeneous situations. The main new effect is an underlying lattice which is being refined during dynamical changes of the volume. In general, this leads to a new feature of dynamical difference equations which may not have constant step-size, posing new mathematical problems. It is discussed how such models can be evaluated and what lattice refinements imply for semiclassical behavior. Two detailed examples illustrate that stability conditions can put strong constraints on suitable refinement models, even in the absence of a fundamental Hamiltonian which defines changes of the underlying lattice. Thus, a large class of consistency tests of loop quantum gravity becomes available. In this context, it will also be seen that quantum corrections due to inverse powers of metric components in a constraint are much larger than they appeared recently in more special treatments of isotropic, free scalar models where they were artificially suppressed

  13. Anisotropic diffusion of water molecules in hydroxyapatite nanopores

    Science.gov (United States)

    Prakash, Muthuramalingam; Lemaire, Thibault; Caruel, Matthieu; Lewerenz, Marius; de Leeuw, Nora H.; Di Tommaso, Devis; Naili, Salah

    2017-07-01

    New insights into the dynamical properties of water in hydroxyapatite (HAP) nanopores, a model system for the fluid flow within nanosize spaces inside the collagen-apatite structure of bone, were obtained from molecular dynamics simulations of liquid water confined between two parallel HAP surfaces of different sizes (20 Å ≤ H ≤ 240 Å). Calculations were conducted using a core-shell interatomic potential for HAP together with the extended simple point charge model for water. This force field gives an activation energy for water diffusion within HAP nanopores that is in excellent agreement with available experimental data. The dynamical properties of water within the HAP nanopores were quantified in terms of the second-order water diffusion tensor. Results indicate that water diffuses anisotropically within the HAP nanopores, with the solvent molecules moving parallel to the surface twice as fast as the perpendicular direction. This unusual dynamic behaviour is linked to the strong polarizing effect of calcium ions, and the synergic interactions between the water molecules in the first hydration layer of HAP with the calcium, hydroxyl, and phosphate ions, which facilitates the flow of water molecules in the directions parallel to the HAP surface.

  14. Strongly Correlated Topological Insulators

    Science.gov (United States)

    2016-02-03

    Strongly Correlated Topological Insulators In the past year, the grant was used for work in the field of topological phases, with emphasis on finding...surface of topological insulators. In the past 3 years, we have started a new direction, that of fractional topological insulators. These are materials...in which a topologically nontrivial quasi-flat band is fractionally filled and then subject to strong interactions. The views, opinions and/or

  15. Tunneling anisotropic magnetoresistance driven by magnetic phase transition.

    Science.gov (United States)

    Chen, X Z; Feng, J F; Wang, Z C; Zhang, J; Zhong, X Y; Song, C; Jin, L; Zhang, B; Li, F; Jiang, M; Tan, Y Z; Zhou, X J; Shi, G Y; Zhou, X F; Han, X D; Mao, S C; Chen, Y H; Han, X F; Pan, F

    2017-09-06

    The independent control of two magnetic electrodes and spin-coherent transport in magnetic tunnel junctions are strictly required for tunneling magnetoresistance, while junctions with only one ferromagnetic electrode exhibit tunneling anisotropic magnetoresistance dependent on the anisotropic density of states with no room temperature performance so far. Here, we report an alternative approach to obtaining tunneling anisotropic magnetoresistance in α'-FeRh-based junctions driven by the magnetic phase transition of α'-FeRh and resultantly large variation of the density of states in the vicinity of MgO tunneling barrier, referred to as phase transition tunneling anisotropic magnetoresistance. The junctions with only one α'-FeRh magnetic electrode show a magnetoresistance ratio up to 20% at room temperature. Both the polarity and magnitude of the phase transition tunneling anisotropic magnetoresistance can be modulated by interfacial engineering at the α'-FeRh/MgO interface. Besides the fundamental significance, our finding might add a different dimension to magnetic random access memory and antiferromagnet spintronics.Tunneling anisotropic magnetoresistance is promising for next generation memory devices but limited by the low efficiency and functioning temperature. Here the authors achieved 20% tunneling anisotropic magnetoresistance at room temperature in magnetic tunnel junctions with one α'-FeRh magnetic electrode.

  16. Modeling the binding of fulvic acid by goethite: the speciation of adsorbed FA molecules

    Science.gov (United States)

    Filius, Jeroen D.; Meeussen, Johannes C. L.; Lumsdon, David G.; Hiemstra, Tjisse; van Riemsdijk, Willem H.

    2003-04-01

    Under natural conditions, the adsorption of ions at the solid-water interface may be strongly influenced by the adsorption of organic matter. In this paper, we describe the adsorption of fulvic acid (FA) by metal(hydr)oxide surfaces with a heterogeneous surface complexation model, the ligand and charge distribution (LCD) model. The model is a self-consistent combination of the nonideal competitive adsorption (NICA) equation and the CD-MUSIC model. The LCD model can describe simultaneously the concentration, pH, and salt dependency of the adsorption with a minimum of only three adjustable parameters. Furthermore, the model predicts the coadsorption of protons accurately for an extended range of conditions. Surface speciation calculations show that almost all hydroxyl groups of the adsorbed FA molecules are involved in outer sphere complexation reactions. The carboxylic groups of the adsorbed FA molecule form inner and outer sphere complexes. Furthermore, part of the carboxylate groups remain noncoordinated and deprotonated.

  17. DNA binding during expanded bed adsorption and factors affecting adsorbent aggregation

    DEFF Research Database (Denmark)

    Arpanaei, Ayyoob; Mathiasen, N.; Hobley, Timothy John

    2008-01-01

    DNA-induced aggregation and contraction of expanded bed adsorption chromatography beds have been examined using strong anion exchanger Q HyperZ and calf thymus DNA in buffers containing added NaCl. Two batches of adsorbent with different ionic capacities were used allowing the effects of different...... tolerance of anion exchangers when binding DNA. However, more importantly. with the adsorbents examined here. attempts to reduce bed aggregation by feedstock conditioning with added salt may increase DNA binding leading to a reduction in expanded bed adsorption performance compromising protein capture...... ligand densities to be examined. Very high dynamic binding capacities at 10% breakthrough were found in the absence of added salt. However, the highest binding capacities (similar to 10 and similar to 19mg DNA ml(-1) gel) were found in buffers containing added salt at concentrations of either 0.25 or 0...

  18. Strong Cosmic Censorship

    Science.gov (United States)

    Isenberg, James

    2017-01-01

    The Hawking-Penrose theorems tell us that solutions of Einstein's equations are generally singular, in the sense of the incompleteness of causal geodesics (the paths of physical observers). These singularities might be marked by the blowup of curvature and therefore crushing tidal forces, or by the breakdown of physical determinism. Penrose has conjectured (in his `Strong Cosmic Censorship Conjecture`) that it is generically unbounded curvature that causes singularities, rather than causal breakdown. The verification that ``AVTD behavior'' (marked by the domination of time derivatives over space derivatives) is generically present in a family of solutions has proven to be a useful tool for studying model versions of Strong Cosmic Censorship in that family. I discuss some of the history of Strong Cosmic Censorship, and then discuss what is known about AVTD behavior and Strong Cosmic Censorship in families of solutions defined by varying degrees of isometry, and discuss recent results which we believe will extend this knowledge and provide new support for Strong Cosmic Censorship. I also comment on some of the recent work on ``Weak Null Singularities'', and how this relates to Strong Cosmic Censorship.

  19. Adsorbed or intercalated: Na on graphene/Ir(111)

    Science.gov (United States)

    Pervan, Petar; Lazić, Predrag

    2017-09-01

    Interaction of sodium with graphene (Gr) on Ir(111) was studied with the aim to resolve the issue of Na adsorption/intercalation kinetics. The system Na/Gr/Ir(111) was studied by means of angle-resolved photoemission spectroscopy, low-energy electron diffraction, and ab initio density functional theory (DFT) calculation. It has been found that at room temperature (RT) and low concentrations Na is dominantly adsorbed on graphene. At higher concentrations, an intercalation process sets in so that it is possible to observe the coexistence of these two states. Eventually, all Na atoms are found in the intercalated state as determined by exposure to oxygen. While adsorption of Na on graphene already intercalated by Na [Na/Gr/Na/Ir(111) system] at RT was not possible, we could observe Li adsorption through the increase of Dirac point binding energy. Li coadsorption strongly affects the binding energy of the iridium surface state as well. This finding was supported by DFT calculations of adsorption energy of Na and Li on bare and fully Na intercalated graphene.

  20. Ion exchangers as adsorbents for removing metals from aquatic media.

    Science.gov (United States)

    Khan, Meraj A; Bushra, Rani; Ahmad, Anees; Nabi, Syed A; Khan, Dilwar A; Akhtar, Arshia

    2014-02-01

    A polyaniline-based composite cation-exchange material was synthesized by way of sol-gel method and studied to explore its analytical and environmental applications. It was characterized by using instrumental analyses [Fourier transform infrared (spectrometer), X-ray, thermogravimetric analysis/differential thermal analysis, standard electron microscopy, and transmission electron microscopy]. Physicochemical studies, such as ion-exchange capacity, pH titrations, and chemical stability, along with effect of eluent concentration and elution, were also performed to exploit the ion-exchange capabilities. pH titration studies showed that the material presents monofunctional strong cation-exchange behavior. This nanocomposite material is semicrystalline in nature and exhibits improved thermal and chemical stability. The partition coefficient studies of different metal ions in the material were performed in demineralised water and different surfactant media, and it was found to be selective for Pb(II) and Hg(II) ions. To exploit the usefulness of the material as an adsorbent, some important quantitative binary separations of metal ions were performed on polyaniline Zr(IV) molybdophosphate columns. This composite cation exchanger can be applied for the treatment of polluted water to remove heavy metals.

  1. A DFT study of Cu nanoparticles adsorbed on defective graphene

    Energy Technology Data Exchange (ETDEWEB)

    García-Rodríguez, D.E. [Universidad Politécnica de Aguascalientes, Calle Paseo San Gerardo No. 297 Fracc. San Gerardo, 20342 Aguascalientes, Ags. (Mexico); Mendoza-Huizar, L.H. [Universidad Autónoma del Estado de Hidalgo, Área Académica de Química, Ciudad del Conocimiento. Carretera Pachuca-Tulancigo Km. 4.5 Mineral de la Reforma, 42186 Hidalgo (Mexico); Díaz, C., E-mail: cristina.diaz@uam.es [Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid (Spain); Institute for Advanced Research in Chemical Science (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2017-08-01

    Highlights: • Cu{sub n} supported on graphene may be a promising electrode material for DBFC's cells. • Cu{sub n}/graphene interaction is rather local and size independent. • Cu{sub 13} anchors strongly to defects in graphene, while keeping its gas-phase properties. - Abstract: Metal nanoparticles adsorbed on graphene are systems of interest for processes relative to catalytic reactions and alternative energy production. Graphene decorated with Cu-nanoparticles, in particular, could be a good alternative material for electrodes in direct borohydride fuel cells. However our knowledge of this system is still very limited. Based on density functional theory, we have analyzed the interaction of Cu{sub n} nanoparticles (n = 4, 5, 6, 7, 13) with pristine and defective-graphene. We have considered two types of defects, a single vacancy (SV), and an extended lineal structural defect (ELSD), formed by heptagon-pentagon pairs. Our analysis has revealed the covalent character of the Cu{sub n}-graphene interaction for pristine- and ELSD-graphene, and a more ionic-like interaction for SV-graphene. Furthermore, our analysis shows that the interaction between the nanoparticles and the graphene is rather local, i.e., only the nanoparticle atoms close to the contact region are involved in the interaction, being the electronic contact region much higher for defective-graphene than for pristine-graphene. Thus, the higher the particle the lower its average electronic and structural distortion.

  2. A DFT study of Cu nanoparticles adsorbed on defective graphene

    International Nuclear Information System (INIS)

    García-Rodríguez, D.E.; Mendoza-Huizar, L.H.; Díaz, C.

    2017-01-01

    Highlights: • Cu n supported on graphene may be a promising electrode material for DBFC's cells. • Cu n /graphene interaction is rather local and size independent. • Cu 13 anchors strongly to defects in graphene, while keeping its gas-phase properties. - Abstract: Metal nanoparticles adsorbed on graphene are systems of interest for processes relative to catalytic reactions and alternative energy production. Graphene decorated with Cu-nanoparticles, in particular, could be a good alternative material for electrodes in direct borohydride fuel cells. However our knowledge of this system is still very limited. Based on density functional theory, we have analyzed the interaction of Cu n nanoparticles (n = 4, 5, 6, 7, 13) with pristine and defective-graphene. We have considered two types of defects, a single vacancy (SV), and an extended lineal structural defect (ELSD), formed by heptagon-pentagon pairs. Our analysis has revealed the covalent character of the Cu n -graphene interaction for pristine- and ELSD-graphene, and a more ionic-like interaction for SV-graphene. Furthermore, our analysis shows that the interaction between the nanoparticles and the graphene is rather local, i.e., only the nanoparticle atoms close to the contact region are involved in the interaction, being the electronic contact region much higher for defective-graphene than for pristine-graphene. Thus, the higher the particle the lower its average electronic and structural distortion.

  3. Investigation of anisotropic thermal transport in cross-linked polymers

    Science.gov (United States)

    Simavilla, David Nieto

    Thermal transport in lightly cross-linked polyisoprene and polybutadine subjected to uniaxial elongation is investigated experimentally. We employ two experimental techniques to assess the effect that deformation has on this class of materials. The first technique, which is based on Forced Rayleigh Scattering (FRS), allows us to measure the two independent components of the thermal diffusivity tensor as a function of deformation. These measurements along with independent measurements of the tensile stress and birefringence are used to evaluate the stress-thermal and stress-optic rules. The stress-thermal rule is found to be valid for the entire range of elongations applied. In contrast, the stress-optic rule fails for moderate to large stretch ratios. This suggests that the degree of anisotropy in thermal conductivity depends on both orientation and tension in polymer chain segments. The second technique, which is based on infrared thermography (IRT), allows us to measure anisotropy in thermal conductivity and strain induced changes in heat capacity. We validate this method measurements of anisotropic thermal conductivity by comparing them with those obtained using FRS. We find excellent agreement between the two techniques. Uncertainty in the infrared thermography method measurements is estimated to be about 2-5 %. The accuracy of the method and its potential application to non-transparent materials makes it a good alternative to extend current research on anisotropic thermal transport in polymeric materials. A second IRT application allows us to investigate the dependence of heat capacity on deformation. We find that heat capacity increases with stretch ratio in polyisoprene specimens under uniaxial extension. The deviation from the equilibrium value of heat capacity is consistent with an independent set of experiments comparing anisotropy in thermal diffusivity and conductivity employing FRS and IRT techniques. We identify finite extensibility and strain

  4. Anisotropic magnetoresistance and thermodynamic fluctuations in high-temperature superconductors

    International Nuclear Information System (INIS)

    Heine, G.

    1999-05-01

    Measurements of the in-plane and out-of-plane resistivity and the transverse and longitudinal in-plane and out-of-plane magnetoresistance above T, are reported in the high-temperature superconductors Bi2Sr2CaCu208+' and YBa2CU307 b . The carrier concentration of the Bi2Sr2CaCu208+' single crystals covers a broad range of the phase diagram from the slightly under doped to the moderately over doped region. The doping concentration of the thin films ranges from strongly under doped to optimally doped. The in-plane resistivities obey a metallic-like temperature dependence with a positive magnetoresistance in the transverse and the longitudinal orientation of the magnetic field. The out-of-plane resistivities show an activated behavior above T, with a metallic region at higher temperatures and negative magnetoresistance. The data were analyzed in the framework of a model for superconducting order parameter fluctuations. The positive in-plane magnetoresistance of the highly anisotropic Bi2Sr2CaCu208+x single crystals is interpreted as the suppression of the fluctuation-conductivity enhancement including orbital and spin contributions, whereas the negative magnetoresistance arises from the reduction of the fluctuation-induced pseudogap in the single-electron density-of-states by the magnetic field. For higher temperatures a transition to the normal-state magnetoresistance occurs for the in-plane transport. In the less anisotropic YBa2CU307 b thin films the positive out-of-plane magnetoresistance near T, changes sign to a negative magnetoresistance at higher temperatures. This behavior is also consistent with predictions from the theory of thermodynamic order-parameter fluctuations. The agreement of the fluctuation theory with the experimental findings is excellent for samples from the over doped side of the phase diagram, but deteriorate with decreasing carrier concentration. This behavior is interpreted by the dominating d-wave symmetry of the superconducting order

  5. Milestone Report - Complete New Adsorbent Materials for Marine Testing to Demonstrate 4.5 g-U/kg Adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Christopher James [ORNL; Das, Sadananda [ORNL; Oyola, Yatsandra [ORNL; Mayes, Richard T. [ORNL; Saito, Tomonori [ORNL; Brown, Suree [ORNL; Gill, Gary [PNNL; Kuo, Li-Jung [PNNL; Wood, Jordana [PNNL

    2014-08-01

    This report describes work on the successful completion of Milestone M2FT-14OR03100115 (8/20/2014) entitled, “Complete new adsorbent materials for marine testing to demonstrate 4.5 g-U/kg adsorbent”. This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed two new families of fiber adsorbents that have demonstrated uranium adsorption capacities greater than 4.5 g-U/kg adsorbent after marine testing at PNNL. One adsorbent was synthesized by radiation-induced graft polymerization of itaconic acid and acrylonitrile onto high surface area polyethylene fibers followed by amidoximation and base conditioning. This fiber showed a capacity of 4.6 g-U/kg adsorbent in marine testing at PNNL. The second adsorbent was prepared by atom-transfer radical polymerization of t-butyl acrylate and acrylonitrile onto halide-functionalized round fibers followed by amidoximation and base hydrolysis. This fiber demonstrated uranium adsorption capacity of 5.4 g-U/kg adsorbent in marine testing at PNNL.

  6. Bioavailability of Carbon Nanomaterial-Adsorbed Polycyclic Aromatic Hydrocarbons to Pimphales promelas: Influence of Adsorbate Molecular Size and Configuration.

    Science.gov (United States)

    Linard, Erica N; Apul, Onur G; Karanfil, Tanju; van den Hurk, Peter; Klaine, Stephen J

    2017-08-15

    Despite carbon nanomaterials' (CNMs) potential to alter the bioavailability of adsorbed contaminants, information characterizing the relationship between adsorption behavior and bioavailability of CNM-adsorbed contaminants is still limited. To investigate the influence of CNM morphology and organic contaminant (OC) physicochemical properties on this relationship, adsorption isotherms were generated for a suite of polycyclic aromatic hydrocarbons (PAHs) on multiwalled carbon nanotubes (MWCNTs) and exfoliated graphene (GN) in conjunction with determining the bioavailability of the adsorbed PAHs to Pimphales promelas using bile analysis via fluorescence spectroscopy. Although it appeared that GN adsorbed PAHs indiscriminately compared to MWCNTs, the subsequent bioavailability of GN-adsorbed PAHs was more sensitive to PAH morphology than MWCNTs. GN was effective at reducing bioavailability of linear PAHs by ∼70%, but had little impact on angular PAHs. MWCNTs were sensitive to molecular size, where bioavailability of two-ringed naphthalene was reduced by ∼80%, while bioavailability of the larger PAHs was reduced by less than 50%. Furthermore, the reduction in bioavailability of CNM-adsorbed PAHs was negatively correlated with the amount of CNM surface area covered by the adsorbed-PAHs. This study shows that the variability in bioavailability of CNM-adsorbed PAHs is largely driven by PAH size, configuration and surface area coverage.

  7. Development of laser ablation plasma by anisotropic self-radiation

    Directory of Open Access Journals (Sweden)

    Ohnishi Naofumi

    2013-11-01

    Full Text Available We have proposed a method for reproducing an accurate solution of low-density ablation plasma by properly treating anisotropic radiation. Monte-Carlo method is employed for estimating Eddington tensor with limited number of photon samples in each fluid time step. Radiation field from ablation plasma is significantly affected by the anisotropic Eddington tensor. Electron temperature around the ablation surface changes with the radiation field and is responsible for the observed emission. An accurate prediction of the light emission from the laser ablation plasma requires a careful estimation of the anisotropic radiation field.

  8. Neutron reflectivity study of adsorbed diblock copolymers

    International Nuclear Information System (INIS)

    Smith, G.S.; Baker, S.M.; Wages, S.; Hamilton, W.; Toprakcioglu, C.; Field, J.B.; Dai, L.

    1994-01-01

    This paper summarizes our cumulative work on neutron reflectivity studies of polystyrene-poly(vinyl-2-pyridine) (PS-PVP) and polystyrenepolyethylene oxide (PS-PEO) adsorbed at a quartz-solvent interface. Deuterated toluene was chosen as the solvent since it is a good solvent for PS and a poor one for either of the other two blocks. In this case, the polystyrene dangles into the solvent while the other block acts as an anchor. The neutron reflectivity studies reveal that the form of the polymer density profile normal to the substrate may be varied from an extended ''brush'' to a condensed ''mushroom'' conformation by manipulating the ratio of the molecular weights of the two blocks. In addition, we present new data on the PS-PEO system in a poor solvent, deuterated cyclohexane, under conditions of shear flow in Poiseuille geometry. We find that when the PS-PEO diblock is absorbed from cyclohexane and is allowed to relax, the PS chain takes on a ''mushroom'' conformation. However, when the shear is applied, the layer shear thickens due to the PS chains extended to nearly twice their original lengths

  9. Modeling of the financial market using the two-dimensional anisotropic Ising model

    Science.gov (United States)

    Lima, L. S.

    2017-09-01

    We have used the two-dimensional classical anisotropic Ising model in an external field and with an ion single anisotropy term as a mathematical model for the price dynamics of the financial market. The model presented allows us to test within the same framework the comparative explanatory power of rational agents versus irrational agents with respect to the facts of financial markets. We have obtained the mean price in terms of the strong of the site anisotropy term Δ which reinforces the sensitivity of the agent's sentiment to external news.

  10. Strong Arcwise Connectedness

    OpenAIRE

    Espinoza, Benjamin; Gartside, Paul; Kovan-Bakan, Merve; Mamatelashvili, Ana

    2012-01-01

    A space is `n-strong arc connected' (n-sac) if for any n points in the space there is an arc in the space visiting them in order. A space is omega-strong arc connected (omega-sac) if it is n-sac for all n. We study these properties in finite graphs, regular continua, and rational continua. There are no 4-sac graphs, but there are 3-sac graphs and graphs which are 2-sac but not 3-sac. For every n there is an n-sac regular continuum, but no regular continuum is omega-sac. There is an omega-sac ...

  11. Abortion: Strong's counterexamples fail

    DEFF Research Database (Denmark)

    Di Nucci, Ezio

    2009-01-01

    This paper shows that the counterexamples proposed by Strong in 2008 in the Journal of Medical Ethics to Marquis's argument against abortion fail. Strong's basic idea is that there are cases--for example, terminally ill patients--where killing an adult human being is prima facie seriously morally......'s scenarios have some valuable future or admitted that killing them is not seriously morally wrong. Finally, if "valuable future" is interpreted as referring to objective standards, one ends up with implausible and unpalatable moral claims....

  12. Anisotropic propagation imaging of elastic waves in oriented columnar thin films

    Science.gov (United States)

    Coffy, E.; Dodane, G.; Euphrasie, S.; Mosset, A.; Vairac, P.; Martin, N.; Baida, H.; Rampnoux, J. M.; Dilhaire, S.

    2017-12-01

    We report on the observation of strongly anisotropic surface acoustic wave propagation on nanostructured thin films. Two kinds of tungsten samples were prepared by sputtering on a silicon substrate: a conventional thin film with columns normal to the substrate surface, and an oriented columnar architecture using the glancing angle deposition (GLAD) process. Pseudo-Rayleigh waves (PRWs) were imaged as a function of time in x and y directions for both films thanks to a femtosecond heterodyne pump-probe setup. A strong anisotropic propagation as well as a high velocity reduction of the PRWs were exhibited for the GLAD sample. For the wavevector k/2π  =  3  ×  105 m-1 the measured group velocities v x and v y equal 2220 m s-1 for the sample prepared with conventional sputtering, whereas a strong anisotropy appears (v x   =  1600 m s-1 and v y   =  870 m s-1) for the sample prepared with the GLAD process. Using the finite element method, the anisotropy is related to the structural anisotropy of the thin film’s architecture. The drop of PRWs group velocities is mainly assigned to the porous microstructure, especially favored by atomic shadowing effects which appear during the growth of the inclined columns. Such GLAD thin films constitute a new tool for the control of the propagation of surface elastic waves and for the design of new devices with useful properties.

  13. Transport Theory for Plasmas that are Strongly Magnetized and Strongly Coupled

    Science.gov (United States)

    Baalrud, Scott; Daligault, Jerome

    2016-10-01

    Plasmas with components that are magnetized, strongly coupled, or both arise in a variety of frontier plasma physics experiments including magnetized dusty plasmas, nonneutral plasmas, magnetized ICF concepts, as well as from self-generated fields in ICF. Here, a species is considered strongly magnetized if the gyroradius is smaller than the spatial scale over which Coulomb interactions occur. A theory for transport properties is described that treats a wide range of both coupling and magnetization strengths. The approach is based on an extension of the recent effective potential transport theory to include a strong magnetic field. The underlying kinetic theory is based on an extension of the Boltzmann equation to include a strong magnetic field in the dynamics of binary scattering events. Corresponding magnetohydrodynamic equations are derived by solving the kinetic equation using a Chapman-Enskog like spectral method. Results are compared with classical molecular dynamics simulations of self-diffusion of the one component plasmas, and with simulations of parallel to perpendicular temperature equilibration of an initially anisotropic distribution. This material is based upon work supported by AFOSR Award FA9550-16-1-0221 and DOE OFES Award DE-SC0016159.

  14. Hydrodynamic cavitation in Stokes flow of anisotropic fluids.

    Science.gov (United States)

    Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G; Sengupta, Anupam

    2017-05-30

    Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domain nucleates due to sudden pressure drop upon flow past a cylindrical obstacle within a microchannel. For an anisotropic fluid, the inception and growth of the cavitation domain ensued in the Stokes regime, while no cavitation was observed in isotropic liquids flowing under similar hydrodynamic parameters. Using simulations we identify a critical value of the Reynolds number for cavitation inception that scales inversely with the order parameter of the fluid. Strikingly, the critical Reynolds number for anisotropic fluids can be 50% lower than that of isotropic fluids.

  15. Liquid Crystal Elastomer Actuators from Anisotropic Porous Polymer Template.

    Science.gov (United States)

    Wang, Qian; Yu, Li; Yu, Meina; Zhao, Dongyu; Song, Ping; Chi, Hun; Guo, Lin; Yang, Huai

    2017-08-01

    Controlling self-assembly behaviors of liquid crystals is a fundamental issue for designing them as intelligent actuators. Here, anisotropic porous polyvinylidene fluoride film is utilized as a template to induce homogeneous alignment of liquid crystals. The mechanism of liquid crystal alignment induced by anisotropic porous polyvinylidene fluoride film is illustrated based on the relationship between the alignment behavior of liquid crystals and surface microstructure of anisotropic polyvinylidene fluoride film. Liquid crystal elastomer actuators with fast responsiveness, large strain change, and reversible actuation behaviors are achieved by the photopolymerization of liquid crystal monomer in liquid crystal cells coated with anisotropic porous films. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Acoustic frequency filter based on anisotropic topological phononic crystals

    KAUST Repository

    Chen, Zeguo

    2017-11-02

    We present a design of acoustic frequency filter based on a two-dimensional anisotropic phononic crystal. The anisotropic band structure exhibits either a directional or a combined (global + directional) bandgap at certain frequency regions, depending on the geometry. When the time-reversal symmetry is broken, it may introduce a topologically nontrivial bandgap. The induced nontrivial bandgap and the original directional bandgap result in various interesting wave propagation behaviors, such as frequency filter. We develop a tight-binding model to characterize the effective Hamiltonian of the system, from which the contribution of anisotropy is explicitly shown. Different from the isotropic cases, the Zeeman-type splitting is not linear and the anisotropic bandgap makes it possible to achieve anisotropic propagation characteristics along different directions and at different frequencies.

  17. Two-dimensional static deformation of an anisotropic medium

    Indian Academy of Sciences (India)

    1989). Chou (1976) and Ting (1995) discussed antiplane strain deformation of an anisotropic medium. Garg et al (1996) obtained representations of seismic sources causing antiplane strain deformations of orthotropic media. The corresponding ...

  18. Change of energy of photons passing through rotating anisotropic elements

    CERN Document Server

    Bagini, V; Santarsiero, M; Frezza, F; Schettini, G; Schirripa-Spagnolo, G

    1994-01-01

    We discuss simple experiments where the concept of angular momentum of a photon can be put to use in order to explain the photon energy changes that are produced by the passage of light beams through rotating anisotropic elements. (author)

  19. Effects of the molecular rotational dynamics on dielectric and far-infra-red spectra of anisotropic liquids

    International Nuclear Information System (INIS)

    Nordio, P.L.; Segre, U.

    1981-01-01

    Dielectric and far-infra-red spectra of uniaxial liquid-crystal phase are analysed in terms of correlation functions calculated by a memory function formalism. SAIL (strong anisotropic interaction limit) conditions are always found to apply, resulting in diffusional regime at low working frequencies. Dipole friction has been also included in the calculations to consider many-particle interactions, its effect being analogous to the introduction of slowly relaxing local structures. (author)

  20. Strain driven anisotropic magnetoresistance in antiferromagnetic La$_{0.4}$Sr$_{0.6}$MnO$_{3}$

    OpenAIRE

    Wong, A. T.; Beekman, C.; Guo, H.; Siemons, W.; Gai, Z.; Arenholz, E.; Takamura, Y.; Ward, T. Z.

    2014-01-01

    We investigate the effects of strain on antiferromagnetic (AFM) single crystal thin films of La 1-x Sr x MnO 3 (x = 0.6). Nominally unstrained samples have strong magnetoresistance with anisotropic magnetoresistances (AMR) of up to 8%. Compressive strain suppresses magnetoresistance but generates AMR values of up to 63%. Tensile strain presents the only case of a metal-insulator transition and demonstrates a previously unreported AMR behavior. In all three cases, we find evidence of magnetic...

  1. A strong comeback

    International Nuclear Information System (INIS)

    Marier, D.

    1992-01-01

    This article presents the results of a financial rankings survey which show a strong economic activity in the independent energy industry. The topics of the article include advisor turnover, overseas banks, and the increase in public offerings. The article identifies the top project finance investors for new projects and restructurings and rankings for lenders

  2. Fabrication of anisotropic multifunctional colloidal carriers

    Science.gov (United States)

    Jerri, Huda A.

    The field of colloidal assembly has grown tremendously in recent years, although the direct or template-assisted methods used to fabricate complex colloidal constructions from monodisperse micro- and nanoparticles have been generally demonstrated on model materials. In this work, novel core particle syntheses, particle functionalizations and bottom-up assembly techniques are presented to create functional colloidal devices. Using particle lithography, high-information colloidal vectors have been developed and modified with imaging and targeting agents. Localized nanoscale patches have been reliably positioned on microparticles to serve as foundations for further chemical or physical modifications. Site-specific placement of RGD targeting ligands has been achieved in these lithographed patches. Preferential uptake of these targeted vectors by RGD-specific 3T3 fibroblasts was verified using confocal laser scanning microscopy. A transition was made from the functionalization of model imaging core particles to the lithography of colloidal cartridges, in an effort to construct colloidal syringes with specialized, programmable release profiles. A variety of functional, pH-sensitive fluorescent cores were engineered to respond to solution conditions. When triggered, the diverse composite core microparticles and reservoir microcapsules released embedded fluorescent moieties such as dye molecules, and fluorophore-conjugated nanoparticles. The microcapsules, created using layer-by-layer polyelectrolyte deposition on sacrificial templates, were selectively modified with a robust coating. The pH-responsive anisotropic reservoir microcapsules were extremely stable in solution, and exhibited a "Lazarus" functionality of rehydrating to their original state following desiccation. A snapshot of focused-release of core constituents through the lone opening in colloidal monotremes has been obtained by anisotropically-functionalizing degradable cores with barrier shells. Additionally

  3. [Study on LDL adsorbent modified by lauric acid].

    Science.gov (United States)

    Cong, Haixia; Du, Longbing; Fang, Bo; You, Chao

    2010-06-01

    A hydrophobic low-density lipoprotein cholesterol (LDL-C) adsorbent was synthesized with lauric acid and chitosan. The condition for adsorption was obtained by investigating the influence of adsorbent amount and adsorption time. The results of adsorption in vitro showed that the average adsorption rates for total cholesterol (TC), LDL-C, high-density lipoprotein cholesterol (HDL-C) and total protein (TP) were 47.7%, 84.7%, 18.1% and 5.9% respectively. The adsorbent possesses good selectivity in removing LDL-C.

  4. VOC Recovery through Microwave Regeneration of Adsorbents: Process Design Studies.

    Science.gov (United States)

    Price, David W; Schmidt, Philip S

    1998-12-01

    Process design studies are described for a new type of VOC recovery system which uses microwave heating to regenerate adsorbents. Microwave regeneration systems create a highly concentrated effluent from which the VOCs can be recovered by condensation at near-ambient temperatures. Important design considerations, predicated on experimental work and model development, are identified and discussed. Parametric studies are then described that identify the optimal adsorbent selection, operating cycle, recovery configuration, regeneration pressure, regeneration final coverage, and column configuration. In general, it was found that microwave regenerated adsorption systems favor the use of low dielectric loss-factor polymeric adsorbents and operation under low pressure conditions (about 5 torr absolute pressure).

  5. Spin and orbital angular momentum propagation in anisotropic media: theory

    International Nuclear Information System (INIS)

    Picón, Antonio; Benseny, Albert; Mompart, Jordi; Calvo, Gabriel F

    2011-01-01

    This paper is devoted to a study of the propagation of light beams carrying orbital angular momentum in optically anisotropic media. We first review some properties of homogeneous anisotropic media, and describe how the paraxial formalism is modified in order to proceed with a new approach dealing with the general setting of paraxial propagation along uniaxial inhomogeneous media. This approach is suitable for describing space-variant optical-axis phase plates

  6. Hybrid anisotropic materials for wind power turbine blades

    CERN Document Server

    Golfman, Yosif

    2012-01-01

    Based on rapid technological developments in wind power, governments and energy corporations are aggressively investing in this natural resource. Illustrating some of the crucial new breakthroughs in structural design and application of wind energy generation machinery, Hybrid Anisotropic Materials for Wind Power Turbine Blades explores new automated, repeatable production techniques that expand the use of robotics and process controls. These practices are intended to ensure cheaper fabrication of less-defective anisotropic material composites used to manufacture power turbine blades. This boo

  7. Anisotropic wave-equation traveltime and waveform inversion

    KAUST Repository

    Feng, Shihang

    2016-09-06

    The wave-equation traveltime and waveform inversion (WTW) methodology is developed to invert for anisotropic parameters in a vertical transverse isotropic (VTI) meidum. The simultaneous inversion of anisotropic parameters v0, ε and δ is initially performed using the wave-equation traveltime inversion (WT) method. The WT tomograms are then used as starting background models for VTI full waveform inversion. Preliminary numerical tests on synthetic data demonstrate the feasibility of this method for multi-parameter inversion.

  8. Comparison with adsorption of Re (VII) by two different γ-radiation synthesized silica-grafting of vinylimidazole/4-vinylpyridine adsorbents

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Pu [Beijing Key Laboratory for Solid Waste Utilization and Management, Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871,China (China); Han, Dong; Zhai, Maolin [Beijing National Laboratory for Molecular Sciences, Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science, The Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Xu, Ling, E-mail: lingxu@pku.edu.cn [Beijing Key Laboratory for Solid Waste Utilization and Management, Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871,China (China); Li, Huibo, E-mail: hb0012@sina.com [China Institute of Atomic Energy, P.O. Box 275-26, Beijing 102413 (China)

    2017-02-15

    Highlights: • Two Re adsorbents were synthesized by grafting of vinylimidazole and vinylpyridine onto silanized silica gel via γ-radiation. • The Re adsorption capacities of SS-MPTS-VIMH and SS-MPTS-VPQ were 145.99 mg g{sup −1} and 71.08 mg g{sup −1}, respectively. • Both the adsorbents had fast adsorption kinetics, and could be used for column adsorption. • SS-MPTS-VPQ had good anti-interference abilities, and might be used for the disposal of Tc in the future. - Abstract: Two silica gel based adsorbents for Re (VII), i.e. SS-MPTS-VIMH and SS-MPTS-VPQ, were synthesised. Silica gel was used as the matrix for γ-radiation grafting, and the monomer of 1-vinyl imidazole (VIM) and 4-vinylpyridine (4-VP) was grafted onto the silica silanized by methacryloxy propyl trimethoxyl silane, respectively. A VIM concentration of 2 mol L{sup −1} and an absorbed dose of 30 kGy were the optimal grafting conditions for adsorbent SS-MPTS-VIM, and a 4-VP concentration of 4 mol L{sup −1} and an absorbed dose of 40 kGy were the optimal grafting conditions for adsorbent SS-MPTS-VP. At the certain condition, the grafting yield of SS-MPTS-VIM was 30.1% and that of SS-MPTS-VP was 21.0%. The adsorption capacity of adsorbent SS-MPTS-VIMH was 145.99 mg g{sup −1} and that of SS-MPTS-VPQ was 71.08 mg g{sup −1} according to the Langmuir model. The adsorbent SS-MPTS-VPQ had better adsorption properties of acid resistance and anti-interference than SS-MPTS-VIMH. Dynamic column experiments showed that protonated adsorbent SS-MTPS-VIMH could be recycled with good performance while quaternized adsorbent SS-MPTS-VPQ could not. The adsorbent SS-MPTS-VIMH belongs to weak anion exchange adsorbent and SS-MPTS-VPQ belongs to strong anion exchange adsorbent. This study paves a way to the synthesis and application of a novel silica base adsorbents for Re (VII).

  9. Stress propagation in isotropic packs with anisotropic boundaries

    Science.gov (United States)

    Krapf, Nathan; Witten, Thomas

    2010-03-01

    Stresses in marginally jammed, anisotropic packs built up from a solid floor propagate along oblique rays toward the floor footnotetext D. A. Head, A. V. Tkachenko, and T. A. Witten. Eur. Phys. J. E 6, 99-105 (2001)). This clear anisotropic propagation must result from anisotropic packing and/or anisotropic boundary conditions. Here we numerically isolate the effect of anisotropic boundaries by using an explicitly isotropic periodic pack in a marginally jammed, isostatic state. We then remove the periodicity in one direction and anchor the beads along one edge to a substrate. This preserves the isostatic condition while rendering the boundary anisotropic. However, we find hyperstatic modes along one edge of the pack and hypostatic modes at the other. We show that these extra modes decay rapidly away from the boundaries. Remarkably the hypostatic modes cause the pack to be unstable under any force applied to a single bead. This instability can be remedied by applying a suitable cluster of forces to adjacent beads, allowing a clear measurement of the bulk response. We discuss the resulting stress response.

  10. A unified theoretical and experimental study of anisotropic hardening

    International Nuclear Information System (INIS)

    Boehler, J.P.; Raclin, J.

    1981-01-01

    The purpose of this work is to develop a consistent formulation of the constitutive relations regarding anisotropic hardening materials. Attention is focused on the appearance and the evolution of mechanical anisotropies during irreversible processes, such as plastic forming and inelastic deformation of structures. The representation theorems for anisotropic tensor functions constitute a theoretical basis, allowing to reduce arbitrariness and to obtain a unified formulation of anisotropic hardening. In this approach, a general three-dimensional constitutive law is developed for prestrained initially orthotropic materials. Introduction of the plastic behavior results in the general forms of both the flow-law and the yield criterion. The developed theory is then specialized for the case of plane stress and different modes of anisotropic hardening are analyzed. A new generalization of the Von Mises criterion is proposed, in considering a homogeneous form of order two in stress and employing the simplest combinations of the basic invariants entering the general form of the yield condition. The proposed criterion involves specific terms accounting for the initial anisotropy, the deformation induced anisotropy and correlative terms between initial and induced anisotropy. The effects of prestrainings result in both isotropic and anisotropic hardening. An adequate experimental program, consisting of uniaxial tensile tests on oriented specimens of prestrained sheet-metal, was performed, in order to determine the specific form and the evolution of the anisotropic failure criterion for soft-steel subjected to different irreversible prestrainings. (orig.)

  11. Influence of carboxylic ion-pairing reagents on retention of peptides in thin-layer chromatography systems with C18 silica-based adsorbents.

    Science.gov (United States)

    Gwarda, Radosław Ł; Aletańska-Kozak, Monika; Klimek-Turek, Anna; Ziajko-Jankowska, Agnieszka; Matosiuk, Dariusz; Dzido, Tadeusz H

    2016-04-01

    One of the main problems related to chromatography of peptides concerns adverse interactions of their strong basic groups with free silanol groups of the silica based stationary phase. Influence of type and concentration of ion-pairing regents on peptide retention in reversed-phase high-performance liquid chromatography (RP-HPLC) systems has been discussed before. Here we present influence of these mobile phase additives on retention of some peptide standards in high-performance thin-layer chromatography (HPTLC) systems with C18 silica-based adsorbents. We prove, that due to different characteristic of adsorbents used in both techniques (RP HPLC and HPTLC), influence of ion-pairing reagents on retention of basic and/or amphoteric compounds also may be quite different. C18 silica-based HPTLC adsorbents provide more complex mechanism of retention and should be rather considered as mixed-mode adsorbents. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Schroedinger covariance states in anisotropic waveguides

    International Nuclear Information System (INIS)

    Angelow, A.; Trifonov, D.

    1995-03-01

    In this paper Squeezed and Covariance States based on Schroedinger inequality and their connection with other nonclassical states are considered for particular case of anisotropic waveguide in LiNiO 3 . Here, the problem of photon creation and generation of squeezed and Schroedinger covariance states in optical waveguides is solved in two steps: 1. Quantization of electromagnetic field is provided in the presence of dielectric waveguide using normal-mode expansion. The photon creation and annihilation operators are introduced, expanding the solution A-vector(r-vector,t) in a series in terms of the Sturm - Liouville mode-functions. 2. In terms of these operators the Hamiltonian of the field in a nonlinear waveguide is derived. For such Hamiltonian we construct the covariance states as stable (with nonzero covariance), which minimize the Schroedinger uncertainty relation. The evolutions of the three second momenta of q-circumflex j and p-circumflex j are calculated. For this Hamiltonian all three momenta are expressed in terms of one real parameters s only. It is found out how covariance, via this parameter s, depends on the waveguide profile n(x,y), on the mode-distributions u-vector j (x,y), and on the waveguide phase mismatching Δβ. (author). 37 refs

  13. Anisotropic Charged Fluid Sphere in Isotropic Coordinates

    Directory of Open Access Journals (Sweden)

    Neeraj Pant

    2014-01-01

    Full Text Available We have presented a class of charged superdense star models, starting with a static spherically symmetric metric in isotropic coordinates for anisotropic fluid by considering Hajj-Boutros-(1986 type metric potential and a specific choice of electrical intensity E and anisotropy factor Δ which involve charge parameter K and anisotropy parameter α. The solution is well behaved for all the values of Schwarzschild compactness parameter u lying in the range 0

  14. Numerical calculation of spatially variant anisotropic metamaterials

    Science.gov (United States)

    Gulib, Asad Ullah Hil

    3D printing, or additive manufacturing, is rapidly evolving into a mainstream manufacturing technology that is creating new opportunities for electromagnetics and circuits. 3D printing permits circuits to fully utilize the third dimension allowing more functions in the same amount of space and allows the devices to have arbitrary form factors. 3D printing is letting us discover new physics that is not possible in standard 2D circuits and devices. However, evolving electromagnetics and circuits into three dimensions introduces some serious problems like thermal management, interference, and mutual coupling between the components which degrades performance and hurts signal integrity. Metamaterials are engineered composites that exhibit extreme electromagnetic properties and allow extraordinary control over electromagnetic fields. The EM Lab is developing spatially-variant anisotropic metamaterials (SVAMs) as a solution to mitigate mutual coupling between components. The concept of SVAMs is to electrically stretch the space between components to reduce mutual coupling. To do this, alternating layers of different dielectric must bisect adjacent components. However, the overall dielectric fill must also conform around dozens of electrical components and be smooth, continuous, and defect free. The research described here is the first prototype of an algorithm which generates a SVAM infill between all of the electrical components of a circuit in order to reduce the mutual coupling.

  15. P wave anisotropic tomography of the Alps

    Science.gov (United States)

    Hua, Yuanyuan; Zhao, Dapeng; Xu, Yixian

    2017-06-01

    The first tomographic images of P wave azimuthal and radial anisotropies in the crust and upper mantle beneath the Alps are determined by joint inversions of arrival time data of local earthquakes and teleseismic events. Our results show the south dipping European plate with a high-velocity (high-V) anomaly beneath the western central Alps and the north dipping Adriatic plate with a high-V anomaly beneath the Eastern Alps, indicating that the subduction polarity changes along the strike of the Alps. The P wave azimuthal anisotropy is characterized by mountain chain-parallel fast-velocity directions (FVDs) in the western central Alps and NE-SW FVDs in the Eastern Alps, which may be caused by mantle flow induced by the slab subductions. Our results reveal a negative radial anisotropy (i.e., Vph Vph > Vpv) in the low-velocity mantle wedge, which may reflect the subvertical plate subduction and its induced mantle flow. The results of anisotropic tomography provide important new information on the complex mantle structure and dynamics of the Alps and adjacent regions.

  16. Anisotropic behaviour of human gallbladder walls.

    Science.gov (United States)

    Li, W G; Hill, N A; Ogden, R W; Smythe, A; Majeed, A W; Bird, N; Luo, X Y

    2013-04-01

    Inverse estimation of biomechanical parameters of soft tissues from non-invasive measurements has clinical significance in patient-specific modelling and disease diagnosis. In this paper, we propose a fully nonlinear approach to estimate the mechanical properties of the human gallbladder wall muscles from in vivo ultrasound images. The iteration method consists of a forward approach, in which the constitutive equation is based on a modified Hozapfel-Gasser-Ogden law initially developed for arteries. Five constitutive parameters describing the two orthogonal families of fibres and the matrix material are determined by comparing the computed displacements with medical images. The optimisation process is carried out using the MATLAB toolbox, a Python code, and the ABAQUS solver. The proposed method is validated with published artery data and subsequently applied to ten human gallbladder samples. Results show that the human gallbladder wall is anisotropic during the passive refilling phase, and that the peak stress is 1.6 times greater than that calculated using linear mechanics. This discrepancy arises because the wall thickness reduces by 1.6 times during the deformation, which is not predicted by conventional linear elasticity. If the change of wall thickness is accounted for, then the linear model can used to predict the gallbladder stress and its correlation with pain. This work provides further understanding of the nonlinear characteristics of human gallbladder. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Anisotropic reflectance characteristics of natural Earth surfaces.

    Science.gov (United States)

    Brennan, B; Bandeen, W R

    1970-02-01

    The patterns of reflection of solar radiation from cloud, water, and land surfaces were measured with an aircraft-borne medium resolution radiometer. Reflectances in the 0.2-4.0-micro and 0.55-0.85-micro portions of the electromagnetic spectrum were investigated. Results indicate that the reflectance characteristics of most of the surface types measured are anisotropic. The anisotropy is dependent on the type of surface and the angles of incidence and reflection. In general, the anisotropy increases with increasing solar zenith angle. Clouds and forests show similar reflectance patterns, with forward and backward scattering peaks. Ocean surfaces yield a pattern similar to those of the clouds and forests but with an additional peak which is associated with sun glitter. Reflectances measured in the 0.2-4.0-micro band are generally lower than those in the 0.55-0.85-micro band under cloudy conditions. Anisotropy and spectral bandwidth should be accounted for when computing the albedo of the earth from narrow field-of-view measurements from satellites; otherwise, large errors may be expected to occur.

  18. Eliminating Heavy Metals from Water with NanoSheet Minerals as Adsorbents

    Directory of Open Access Journals (Sweden)

    Shaoxian Song

    2017-12-01

    . Montmorillonite was usually pre-interacted with organics to increase the interlayer space, and then exfoliated to single or several layers by using ultrasonic. Among the nano-sheets, the surfaces are strongly charged negatively, while the edges are positively charged. This characteristic allows the adsorption of cations or anions, as well as the substances with negative or positive charges. Graphite can be oxidized and exfoliated into graphene oxide (GO, which has a huge specific surface area and plentiful of functional groups such as carboxyl, epoxy, carbonyl and hydroxyl, leading to high adsorption capacity to heavy metals in water. Nano-sheet molybdenite is a novel two-dimensional material with single or several layers of MoS2 sheets. The most common method to prepare nano-sheet molybdenite is exfoliated from bulk molybdenite through chemical method based on ion intercalation process. A large quantity of functional groups and S atom on the sheets are the active sites for adsorbing heavy metals in water. Nano-sheet minerals are used as adsorbents in the form of three-dimension hydrogels. They are featured by the huge specific surface area and high adsorption efficiency. In addition, the clean and smooth surfaces allow heavy metals to adsorb directly by film dispersion. Without any barrier of mesopores and micropores, the adsorption rate could be well improved. These characteristics would lead to the extremely large adsorption capacity and high adsorption rate. Currently, nano-sheet minerals as adsorbent is a very hot research topic in the field of heavy metal removal. It is expected that nanosheet minerals will be promising adsorbents in the removal of heavy metals from water.

  19. Dynamics of CO 2 Adsorption on Amine Adsorbents. 2. Insights Into Adsorbent Design

    KAUST Repository

    Bollini, Praveen

    2012-11-21

    Packed bed breakthrough experiments are reported for commercial zeolite 13X and 3-aminopropyl-functionalized SBA-15 silica materials with three different amine loadings. Mass and heat transfer dynamics for all four materials are modeled successfully. Amine adsorbents with open pores are found to exhibit faster mass diffusion rates compared to zeolite 13X. When amine loading is increased by coupling aminopropyl groups, premature breakthrough combined with a long tail is observed. Contrary to conventional physisorbants, finite heat losses to the column wall do not explain the long breakthrough tail. A rate model that accounts for heterogeneity in diffusion was found to accurately capture the breakthrough shape of the high loading material. Batch uptake measurements support the hypothesis that slow diffusion through the polymer phase is what hampers adsorption kinetics in the high amine loading adsorbent. The results emphasize the importance of designing materials that are not overloaded with amine sites, as excessive amine loadings can lead to depressed adsorption kinetics and premature column breakthrough. © 2012 American Chemical Society.

  20. Strong Electroweak Symmetry Breaking

    CERN Document Server

    Grinstein, Benjamin

    2011-01-01

    Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...

  1. Natural waste materials containing chitin as adsorbents for textile dyestuffs: batch and continuous studies.

    Science.gov (United States)

    Figueiredo, S A; Loureiro, J M; Boaventura, R A

    2005-10-01

    In this work three natural waste materials containing chitin were used as adsorbents for textile dyestuffs, namely the Anodonta (Anodonta cygnea) shell, the Sepia (Sepia officinalis) and the Squid (Loligo vulgaris) pens. The selected dyestuffs were the Cibacron green T3G-E (CI reactive green 12), and the Solophenyl green BLE 155% (CI direct green 26), both from CIBA, commonly used in cellulosic fibres dyeing, the most used fibres in the textile industry. Batch equilibrium studies showed that the materials' adsorption capacities increase after a simple and inexpensive chemical treatment, which increases their porosity and chitin relative content. Kinetic studies suggested the existence of a high internal resistance in both systems. Fixed bed column experiments performed showed an improvement in adsorbents' behaviour after chemical treatment. However, in the column experiments, the biodegradation was the main mechanism of dyestuff removal, allowing the materials' bioregeneration. The adsorption was strongly reduced by the pore clogging effect of the biomass. The deproteinised Squid pen (grain size 0.500-1.41 mm) is the adsorbent with highest adsorption capacity (0.27 and 0.037 g/g, respectively, for the reactive and direct dyestuffs, at 20 degrees C), followed by the demineralised Sepia pen and Anodonta shell, behaving like pure chitin in all experiments, but showing inferior performances than the granular activated carbon tested in the column experiments.

  2. Primary events following electron injection into water and adsorbed water layers

    International Nuclear Information System (INIS)

    Barnett, R.N.; Landman, U.; Nitzan, A.

    1990-01-01

    The initial stages of the evolution of an electron injected into bulk water (at 300 K) and into thin water films (1--4 monolayers) adsorbed on a Pt(111) substrate at 50 K are investigated. It is shown that for electrons injected into bulk water with an initial translational kinetic energy between 1.54 and 6.18 eV (i.e., subexcitation energies), the electron momentum time-correlation function left-angle p(0)p(t)right-angle, decays to zero on a time scale of less than 1 fs, reflecting strong backscattering of the electron by the water molecules. On this time scale the electron propagation in the medium is dominated by elastic processes. Furthermore, during this initial stage the system is well represented by a static aqueous medium. Transmission of electrons injected into thin films of adsorbed water is also dominated by elastic scattering. The dependence of the electron transmission probability on the film thickness and the initial injection energy are in accord with recent experimental results of photoinjected electrons into adsorbed water films

  3. Adsorbate shape selectivity: Separation of the HF/134a azeotrope over carbogenic molecular sieve

    Energy Technology Data Exchange (ETDEWEB)

    Hong, A.; Mariwala, R.K.; Kane, M.S.; Foley, H.C. [Univ. of Delaware, Nework, DE (United States)

    1995-03-01

    Experimental evidence is provided for adsorptive shape selectivity in the separation of the azeotrope between HF and 1,1,1,2-tetrafluoroethane (134a) over pyrolyzed poly(furfuryl alcohol)-derived carbogenic molecular sieve (PPFA-CMS). The separation can be accomplished over coconut charcoal or Carbosieve G on the basis of the differences in the extent of equilibrium adsorption of HF and 134a. On these adsorbents 134a is more strongly bound than HF, thus it elutes much more slowly from the bed. The heat of adsorption for 134a in the vicinity of 200 C on Carbosieve G is {approximately}8.8 kcal/mol. In contrast, when the same azeotropic mixture is separated over PPFA-CMS prepared at 500 C, 134a is not adsorbed. As a result 134a elutes from the bed first, followed by HF. The reversal is brought about by the narrower pore size and pore size distribution of the PPFA-CMS versus that for Carbosieve G. Thus the separation over PPFA-CMS is an example of adsorbate shape selectivity and represents a limiting case of kinetic separation.

  4. XPS and XAS investigation of condensed and adsorbed n-octane on a Cu(110) surface

    CERN Document Server

    Weiss, K; Triguero, L; Ogasawara, H; Garnier, M G; Pettersson, L G M; Nilsson, A

    2003-01-01

    The electronic structure of n-octane adsorbed on Cu(110) is studied by using X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) in combination with cluster model calculations in the framework of density functional theory (DFT). The molecule is found to be well oriented on the surface, which is seen from the high degree of XAS dichroism. Saturated hydrocarbons are commonly considered to physisorb on metals such as Cu(110), but still the C 1s XAS spectra reveal large changes in the electronic structure of the adsorbed octane relative to the free molecule. We find that the XAS resonances corresponding to the molecular Rydberg-valence states are strongly quenched upon adsorption and that there is a significant hybridization of the molecular valence orbitals with the metal bands. In addition to a precise interpretation of the XAS spectra, we present details on the molecular orbital structure of the adsorbed octane molecule. We also discuss shifts in the relative binding energies of the ...

  5. Plasmons in strong superconductors

    International Nuclear Information System (INIS)

    Baldo, M.; Ducoin, C.

    2011-01-01

    We present a study of the possible plasmon excitations that can occur in systems where strong superconductivity is present. In these systems the plasmon energy is comparable to or smaller than the pairing gap. As a prototype of these systems we consider the proton component of Neutron Star matter just below the crust when electron screening is not taken into account. For the realistic case we consider in detail the different aspects of the elementary excitations when the proton, electron components are considered within the Random-Phase Approximation generalized to the superfluid case, while the influence of the neutron component is considered only at qualitative level. Electron screening plays a major role in modifying the proton spectrum and spectral function. At the same time the electron plasmon is strongly modified and damped by the indirect coupling with the superfluid proton component, even at moderately low values of the gap. The excitation spectrum shows the interplay of the different components and their relevance for each excitation modes. The results are relevant for neutrino physics and thermodynamical processes in neutron stars. If electron screening is neglected, the spectral properties of the proton component show some resemblance with the physical situation in high-T c superconductors, and we briefly discuss similarities and differences in this connection. In a general prospect, the results of the study emphasize the role of Coulomb interaction in strong superconductors.

  6. Enhanced vanillin production from ferulic acid using adsorbent resin.

    Science.gov (United States)

    Hua, Dongliang; Ma, Cuiqing; Song, Lifu; Lin, Shan; Zhang, Zhaobin; Deng, Zixin; Xu, Ping

    2007-03-01

    High vanillin productivity was achieved in the batch biotransformation of ferulic acid by Streptomyces sp. strain V-1. Due to the toxicity of vanillin and the product inhibition, fed-batch biotransformation with high concentration of ferulic acid was unsuccessful. To solve this problem and improve the vanillin yield, a biotransformation strategy using adsorbent resin was investigated. Several macroporous adsorbent resins were chosen to adsorb vanillin in situ during the bioconversion. Resin DM11 was found to be the best, which adsorbed the most vanillin and the least ferulic acid. When 8% resin DM11 (wet w/v) was added to the biotransformation system, 45 g l(-1) ferulic acid could be added continually and 19.2 g l(-1) vanillin was obtained within 55 h, which was the highest vanillin yield by bioconversion until now. This yield was remarkable for exceeding the crystallization concentration of vanillin and therefore had far-reaching consequence in its downstream processing.

  7. TESTING OF CARBONACEOUS ADSORBENTS FOR REMOVAL OF POLLUTANTS FROM WATER

    Directory of Open Access Journals (Sweden)

    RAISA NASTAS

    2012-03-01

    Full Text Available Testing of carbonaceous adsorbents for removal of pollutants from water. Relevant direction for improving of quality of potable water is application of active carbons at various stages of water treatments. This work includes complex research dealing with testing of a broad spectrum of carbonaceous adsorbents for removal of hydrogen sulfide and nitrite ions from water. The role of the surface functional groups of carbonaceous adsorbents, their acid-basic properties, and the influence of the type of impregnated heteroatom (N, O, or metals (Fe, Cu, Ni, on removal of hydrogen sulfide species and nitrite ions have been researched. The efficiency of the catalyst obtained from peach stones by impregnation with Cu2+ ions of oxidized active carbon was established, being recommended for practical purposes to remove the hydrogen sulfide species from the sulfurous ground waters. Comparative analysis of carbonaceous adsorbents reveals the importance of surface chemistry for oxidation of nitrite ions.

  8. Production of Flocculants, Adsorbents, and Dispersants from Lignin

    Directory of Open Access Journals (Sweden)

    Jiachuan Chen

    2018-04-01

    Full Text Available Currently, lignin is mainly produced in pulping processes, but it is considered as an under-utilized chemical since it is being mainly used as a fuel source. Lignin contains many hydroxyl groups that can participate in chemical reactions to produce value-added products. Flocculants, adsorbents, and dispersants have a wide range of applications in industry, but they are mainly oil-based chemicals and expensive. This paper reviews the pathways to produce water soluble lignin-based flocculants, adsorbents, and dispersants. It provides information on the recent progress in the possible use of these lignin-based flocculants, adsorbents, and dispersants. It also critically discusses the advantages and disadvantages of various approaches to produce such products. The challenges present in the production of lignin-based flocculants, adsorbents, and dispersants and possible scenarios to overcome these challenges for commercial use of these products in industry are discussed.

  9. Production of Flocculants, Adsorbents, and Dispersants from Lignin.

    Science.gov (United States)

    Chen, Jiachuan; Eraghi Kazzaz, Armin; AlipoorMazandarani, Niloofar; Hosseinpour Feizi, Zahra; Fatehi, Pedram

    2018-04-10

    Currently, lignin is mainly produced in pulping processes, but it is considered as an under-utilized chemical since it is being mainly used as a fuel source. Lignin contains many hydroxyl groups that can participate in chemical reactions to produce value-added products. Flocculants, adsorbents, and dispersants have a wide range of applications in industry, but they are mainly oil-based chemicals and expensive. This paper reviews the pathways to produce water soluble lignin-based flocculants, adsorbents, and dispersants. It provides information on the recent progress in the possible use of these lignin-based flocculants, adsorbents, and dispersants. It also critically discusses the advantages and disadvantages of various approaches to produce such products. The challenges present in the production of lignin-based flocculants, adsorbents, and dispersants and possible scenarios to overcome these challenges for commercial use of these products in industry are discussed.

  10. Adsorption of remazol brilliant blue on an orange peel adsorbent

    Directory of Open Access Journals (Sweden)

    M. R. Mafra

    2013-09-01

    Full Text Available A novel orange peel adsorbent developed from an agricultural waste material was characterised and utilised for the removal of Remazol Brilliant Blue from an artificial textile-dye effluent. The adsorption thermodynamics of this dye-adsorbent pair was studied in a series of equilibrium experiments. The time to reach equilibrium was 15 h for the concentration range of 30 mg L-1 to 250 mg L-1. The adsorption capacity decreased with increasing temperature, from 9.7 mg L-1 at 20 ºC to 5.0 mg L-1 at 60 ºC. Both the Langmuir and Freundlich isotherm models fitted the adsorption data quite reasonably. The thermodynamic analysis of dye adsorption onto the orange peel adsorbent indicated its endothermic and spontaneous nature. Thus, the application of orange peel adsorbent for the removal of dye from a synthetic textile effluent was successfully demonstrated.

  11. Adsorption of uranium on adsorbents produced from used tires

    International Nuclear Information System (INIS)

    Mahramanlioglu, M.

    2003-01-01

    Potential use of adsorbents produced from used tires for the removal of uranium from aqueous solutions is investigated. Two different adsorbents were used including char and activated carbon produced from used tires. The surface area was larger on activated carbon. Adsorption experiments were carried out as a function of time, adsorbent concentration, pH and initial concentration of uranium. The adsorption kinetics was found to follow the Lagergren equation. The rate constants of intraparticle diffusion and mass transfer coefficients were calculated. It was shown that the equilibrium data could be fitted by the Langmuir and Freundlich equations. The adsorption of uranium in the presence of different cations were also studied and the results were correlated with the ionic potential of the cations. It was demonstrated that the activated carbon produced from used tires can be considered as an adsorbent that has a commercial potential for uranium removal. (author)

  12. Low Pressure Adsorbent for Recovery & Storage Vented Hydrogen, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A high performance fullerene-based adsorbent is proposed for recovery and storage hydrogen and separating helium via pressure-swing-adsorption (PSA) process....

  13. Order-disorder transitions in adsorbed systems on magnetic surfaces

    International Nuclear Information System (INIS)

    Aguilera-Granja, F.; Moran-Lopez, J.L.; Instituto Politecnico Nacional, Mexico City. Centro de Investigacion y de Estudios Avanzados); Falicov, L.M.

    1984-01-01

    It is investigated the effect of adsorbed atoms on the magnetic properties of ferromagnets. The Ising model is employed considering nearest neigbours with antiferromagnetic coupling between atoms. (M.W.O.) [pt

  14. Oil palm biomass as an adsorbent for heavy metals.

    Science.gov (United States)

    Vakili, Mohammadtaghi; Rafatullah, Mohd; Ibrahim, Mahamad Hakimi; Abdullah, Ahmad Zuhairi; Salamatinia, Babak; Gholami, Zahra

    2014-01-01

    Many industries discharge untreated wastewater into the environment. Heavy metals from many industrial processes end up as hazardous pollutants of wastewaters.Heavy metal pollution has increased in recent decades and there is a growing concern for the public health risk they may pose. To remove heavy metal ions from polluted waste streams, adsorption processes are among the most common and effective treatment methods. The adsorbents that are used to remove heavy metal ions from aqueous media have both advantages and disadvantages. Cost and effectiveness are two of the most prominent criteria for choosing adsorbents. Because cost is so important, great effort has been extended to study and find effective lower cost adsorbents.One class of adsorbents that is gaining considerable attention is agricultural wastes. Among many alternatives, palm oil biomasses have shown promise as effective adsorbents for removing heavy metals from wastewater. The palm oil industry has rapidly expanded in recent years, and a large amount of palm oil biomass is available. This biomass is a low-cost agricultural waste that exhibits, either in its raw form or after being processed, the potential for eliminating heavy metal ions from wastewater. In this article, we provide background information on oil palm biomass and describe studies that indicate its potential as an alternative adsorbent for removing heavy metal ions from wastewater. From having reviewed the cogent literature on this topic we are encouraged that low-cost oil-palm-related adsorbents have already demonstrated outstanding removal capabilities for various pollutants.Because cost is so important to those who choose to clean waste streams by using adsorbents, the use of cheap sources of unconventional adsorbents is increasingly being investigated. An adsorbent is considered to be inexpensive when it is readily available, is environmentally friendly, is cost-effective and be effectively used in economical processes. The

  15. Residence time determination for adsorbent beds of different configurations

    Energy Technology Data Exchange (ETDEWEB)

    Otermat, J.E.; Wikoff, W.O.; Kovach, J.L.

    1995-02-01

    The residence time calculations of ASME AG-1 Code, Section FC, currently specify a screen surface area method, that is technically incorrect. Test data has been obtained on Type II adsorber trays of different configurations to establish residence time in the adsorber trays. These data indicate that the air volume/carbon volume ratio or the average screen area are more appropriate for the calculation of the residence time calculation than the currently used, smallest screen area basis.

  16. Simulations of the Static Friction Due to Adsorbed Molecules

    OpenAIRE

    He, Gang; Robbins, Mark O.

    2001-01-01

    The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and interaction potenti...

  17. Residence time determination for adsorbent beds of different configurations

    International Nuclear Information System (INIS)

    Otermat, J.E.; Wikoff, W.O.; Kovach, J.L.

    1995-01-01

    The residence time calculations of ASME AG-1 Code, Section FC, currently specify a screen surface area method, that is technically incorrect. Test data has been obtained on Type II adsorber trays of different configurations to establish residence time in the adsorber trays. These data indicate that the air volume/carbon volume ratio or the average screen area are more appropriate for the calculation of the residence time calculation than the currently used, smallest screen area basis

  18. Efficient adsorbents of nanoporous aluminosilicate monoliths for organic dyes from aqueous solution.

    Science.gov (United States)

    El-Safty, Sherif A; Shahat, Ahmed; Awual, Md Rabiul

    2011-07-01

    Growing public awareness on the potential risk to humans of toxic chemicals in the environment has generated demand for new and improved methods for toxicity assessment and removal, rational means for health risk estimation. With the aim of controlling nanoscale adsorbents for functionality in molecular sieving of organic pollutants, we fabricated cubic Im3m mesocages with uniform entrance and large cavity pores of aluminosilicates as highly promising candidates for the colorimetric monitoring of organic dyes in an aqueous solution. However, a feasible control over engineering of three-dimensional (3D) mesopore cage structures with uniform entrance (~5 nm) and large cavity (~10 nm) allowed the development of nanoadsorbent membranes as a powerful tool for large-quantity and high-speed (in minutes) adsorption/removal of bulk molecules such as organic dyes. Incorporation of high aluminum contents (Si/Al=1) into 3D cubic Im3m cage mesoporous silica monoliths resulted in small, easy-to-use optical adsorbent strips. In such adsorption systems, natural surfaces of active acid sites of aluminosilicate strips strongly induced both physical adsorption of chemically responsive dyes and intraparticle diffusion into cubic Im3m mesocage monoliths. Results likewise indicated that although aluminosilicate strips with low Si/Al ratios exhibit distortion in pore ordering and decrease in surface area and pore volume, enhancement of both molecular converges and intraparticle diffusion onto the network surfaces and into the pore architectures of adsorbent membranes was achieved. Moreover, 3D mesopore cage adsorbents are reversible, offering potential for multiple adsorption assays. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. AC microcalorimetry of adsorbates on evaporated metal films: Orientational ordering of H sub 2 multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, R.B.

    1991-11-01

    We have improved and extended a novel ac calorimetric technique for measuring the heat capacity of adsorbates on evaporated metal films. Metallic substrates are of particular interest in current studies of the thermodynamics of adsorbed molecules. The method described in the present work is only calorimetric technique which allows measurements of molecules on simple metallic surfaces. Among other improvements, we have achieved significant progress in the preparation and characterization of the evaporated metal film. We have applied this novel technique to a study of hydrogen multilayers on gold and sapphire substrates. We have shown that samples of normal-hydrogen with a nominal coverage n of approximately 25 monolayers (ML) undergo a bulk-like orientational ordering transition. The transition is suppressed as the coverage is decreased, and no sign of the transition remains above 1.6 K for n {approx} 1 ML. For n {approx lt} 8 ML, the peak in the heat capacity exhibits signs of finite-size effects. At higher coverages, finite-size effects are not observed, and the shape of the peak depends strongly on the substrate. We conclude that the peak is inhomogeneously broadened for n {approx lt} 8 ML. This work represents the first measurements of the heat capacity due to orientational ordering in adsorbed hydrogen. The results of an earlier experiment involving vibrational spectroscopy of adsorbed molecules are included in the Appendix. In this work, we have used infrared emission spectroscopy to study the spectral region in the vicinity of the C=O stretch vibration of bridge-bonded CO on Pt(111).

  20. Determination of Points of Zero Charge of Natural and Treated Adsorbents

    Science.gov (United States)

    Nasiruddin Khan, M.; Sarwar, Anila

    Although particle size and its measurement are intuitively familiar to particle technologists, the concept of point of zero charge (pzc) is less widely understood and applied. This is unfortunate since it is at least as fundamentally important as particle size in determining the behavior of particulate materials, especially those with sizes in the colloidal range below a micrometer. pzc is related to the charge on the surface of the particle and strongly depends on the pH of the material; so it influences a wide range of properties of colloidal materials, such as their stability, interaction with electrolytes, suspension rheology, and ion exchange capacity. The pH dependence of surface charges was quantified for four different adsorbent-aqueous solution interfaces. The points of zero charge were determined for activated charcoal, granite sand, lakhra coal, and ground corn cob materials using three methods: (1) the pH drift method, measuring pH where the adsorbent behaves as a neutral specie; (2) potentiometric titration, measuring the adsorption of H+ and OH- on surfaces in solutions of varying ionic strengths; (3) direct assessment of the surface charge via nonspecific ion adsorption as a function of pH. The intrinsic acidity constants for acid and base equilibria, pK a1 s and pK a2 s, were also calculated. Lakhra coal was found to have the lowest pzc value among all other adsorbents studied owing to the presence of a large amount of humus material. The results were used to explain general connections among points of zero charges, cation exchange capacity, and base saturation % of adsorbents.

  1. Effect of interfacial properties on the activation volume of adsorbed enzymes.

    Science.gov (United States)

    Schuabb, Vitor; Cinar, Süleyman; Czeslik, Claus

    2016-04-01

    We have studied the enzymatic activities of α-chymotrypsin (α-CT) and horseradish peroxidase (HRP) that are adsorbed on various chemically modified planar surfaces under aqueous solution. The enzymes were adsorbed on bare quartz, hydrophobic poly(styrene) (PS), positively charged poly(allylamine hydrochloride) (PAH), and negatively charged poly(styrene sulfonate) (PSS). Activation volumes of the enzymes at the aqueous-solid interfaces were determined by using high-pressure total internal reflection fluorescence (TIRF) spectroscopy. Apparently, the pressure response of the adsorbed enzymes strongly depends on the interfacial properties. α-CT can be activated by pressure (increasing enzymatic rate) on negatively charged surfaces like quartz and PSS, whereas HRP is activated by pressure on hydrophobic PS. Corresponding negative activation volumes of -29 mL mol(-1) for α-CT on quartz, -23 mL mol(-1) for α-CT on PSS, and -35 mL mol(-1) for HRP on PS are found. In addition, the absolute activities of α-CT and HRP on quartz, PS, PAH and PSS were determined by UV absorption at ambient pressure. Remarkably, large activities are found on those surfaces that are associated with negative activation volumes. However, Fourier transform infrared (FTIR) spectra collected in attenuated total reflection (ATR) mode do not indicate major adsorption induced conformational changes of the enzymes at any interface studied. Overall, the results of this study show that the activity of immobilized enzymes can largely be enhanced by the right combination of adsorbent material and applied pressure. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Relaxation and crystallization phenomena of water adsorbed to cellulose

    International Nuclear Information System (INIS)

    Czihak, Ch.; Mueller, M.; Schober, H.; Vogl, G.

    1999-01-01

    Complete text of publication follows. Cellulose, the most abundant biopolymer whose unit is D-anhydroglucose pyranose, has a tendency to adsorb water due to unsaturated hydroxyl groups in low ordered regions. This adsorbed water is present in the temperature range of 200 K < T < 273 K in different modifications. Due to voids and pores within and between the cellulose fibers, water molecules are able to build crystalline aggregations. Beyond that, water is able to penetrate the low ordered regions [1] and it adsorbs to cellulose chains. As introduced earlier in [2], the adsorbed water freezes to an amorphous like ice, while above T = 200 K an onset of relaxational motion on different time-scales (ns, ps) occurs. Recent neutron diffraction and INS data of water adsorbed to amorphous cellulose are shown as a new model system. Together with earlier experiments, the characteristics of relaxational motions are summarized and similarities to a glass transition of adsorbed water are discussed. (author) [1] J.M. Ioelovits and M. Gordeev, Acta Polymer. 45, 121-123 (1994); [2] J.C. Czihak, M. Mueller, H. Schober, L. Heux, G. Vogl, Physica B 266, 878-91. (1999)

  3. Efforts to Consolidate Chalcogels with Adsorbed Iodine

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Brian J.; Pierce, David A.; Chun, Jaehun

    2013-08-28

    This document discusses ongoing work with non-oxide aerogels, called chalcogels, that are under development at the Pacific Northwest National Laboratory as sorbents for gaseous iodine. Work was conducted in fiscal year 2012 to demonstrate the feasibility of converting Sn2S3 chalcogel without iodine into a glass. This current document summarizes the work conducted in fiscal year 2013 to assess the consolidation potential of non-oxide aerogels with adsorbed iodine. The Sn2S3 and Sb13.5Sn5S20 chalcogels were selected for study. The first step in the process for these experiments was to load them with iodine (I2). The I2 uptake was ~68 mass% for Sn2S3 and ~50 mass% for Sb13.5Sn5S20 chalcogels. X-ray diffraction (XRD) of both sets of sorbents showed that metal-iodide complexes were formed during adsorption, i.e., SnI4 for Sn2S3 and SbI3 for Sb13.5Sn5S20. Additionally, metal-sulfide-iodide complexes were formed, i.e., SnSI for Sn2S3 and SbSI for Sb13.5Sn5S20. No XRD evidence for unreacted iodine was found in any of these samples. Once the chalcogels had reached maximum adsorption, the consolidation potential was assessed. Here, the sorbents were heated for consolidation in vacuum-sealed quartz vessels. The Sb13.5Sn5S20 chalcogel was heated both (1) in a glassy carbon crucible within a fused quartz tube and (2) in a single-containment fused quartz tube. The Sn2S3 chalcogel was only heated in a single-containment fused quartz tube. In both cases with the single-containment fused quartz experiments, the material consolidated nicely. However, in both cases, there were small fractions of metal iodides not incorporated into the final product as well as fused quartz particles within the melt due to the sample attacking the quartz wall during the heat treatment. The Sb13.5Sn5S20 did not appear to attack the glassy carbon crucible so, for future experiments, it would be ideal to apply a coating, such as pyrolytic graphite, to the inner walls of the fused quartz vessel to prevent

  4. Mechanism of melting in submonolayer films of nitrogen molecules adsorbed on the basal planes of graphite

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Bruch, Ludwig Walter; Taub, H.

    1995-01-01

    The melting mechanism in submonolayer films of N-2 molecules adsorbed on the basal planes of graphite is studied using molecular-dynamics simulations. The melting is strongly correlated with the formation of vacancies in the films. As the temperature increases, the edges of the submonolayer patch...... become atomically rough and vacancies are first created there. Then there is an onset temperature at which the vacancies penetrate into the patch. At an intermediate region of coverages similar to 0.3-0.8 commensurate layers, there is sufficient free volume for the film to melt at that temperature...

  5. Strong-coupling approximations

    International Nuclear Information System (INIS)

    Abbott, R.B.

    1984-03-01

    Standard path-integral techniques such as instanton calculations give good answers for weak-coupling problems, but become unreliable for strong-coupling. Here we consider a method of replacing the original potential by a suitably chosen harmonic oscillator potential. Physically this is motivated by the fact that potential barriers below the level of the ground-state energy of a quantum-mechanical system have little effect. Numerically, results are good, both for quantum-mechanical problems and for massive phi 4 field theory in 1 + 1 dimensions. 9 references, 6 figures

  6. Strong interaction and QFD

    International Nuclear Information System (INIS)

    Ebata, T.

    1981-01-01

    With an assumed weak multiplet structure for bosonic hadrons, which is consistent with the ΔI = 1/2 rule, it is shown that the strong interaction effective hamiltonian is compatible with the weak SU(2) x U(1) gauge transformation. Especially the rho-meson transforms as a triplet under SU(2)sub(w), and this is the origin of the rho-photon analogy. It is also shown that the existence of the non-vanishing Cabibbo angle is a necessary condition for the absence of the exotic hadrons. (orig.)

  7. Gold recovery from low concentrations using nanoporous silica adsorbent

    Science.gov (United States)

    Aledresse, Adil

    The development of high capacity adsorbents with uniform porosity denoted 5%MP-HMS (5% Mercaptopropyl-Hexagonal Mesoporous Structure) to extract gold from noncyanide solutions is presented. The preliminary studies from laboratory simulated noncyanide gold solutions show that the adsorption capacities of these materials are among the highest reported. The high adsorption saturation level of these materials, up to 1.9 mmol/g (37% of the adsorbent weight) from gold chloride solutions (potassium tetrachloroaurate) and 2.9 mmol/g (57% of the adsorbent weight) from gold bromide solutions (potassium tetrabromoaurate) at pH = 2, is a noteworthy feature of these materials. This gold loading from [AuC4]- and [AuBr4 ]- solutions corresponds to a relative Au:S molar ratio of 2.5:1 and 3.8:1, respectively. These rates are significantly higher than the usual 1:1 (Au:S) ratio expected for metal ion binding with the material. The additional gold ions loaded have been spontaneously reduced to metallic gold in the mesoporous material. Experimental studies indicated high maximum adsorptions of gold as high as 99.9% recovery. Another promising attribute of these materials is their favourable adsorption kinetics. The MP-HMS reaches equilibrium (saturation) in less than 1 minute of exposure in gold bromide and less than 10 minutes in gold chloride. The MP-HMS materials adsorption is significantly improved by agitation and the adsorption capacity of Au (III) ions increases with the decrease in pH. The recovery of adsorbed gold and the regeneration of spent adsorbent were investigated for MP-HMS adsorbent. The regenerated adsorbent (MP-HMS) maintained its adsorption capacity even after repeated use and all the gold was successfully recovered from the spent adsorbent. For the fist time, a promising adsorbent system has been found that is capable of effectively concentrating gold thiosulphate complexes, whereas conventional carbon-inpulp (CIP) and carbon-in-leach (CIL) systems fail. The

  8. Structural relaxation in dense liquids composed of anisotropic particles.

    Science.gov (United States)

    Shen, Tianqi; Schreck, Carl; Chakraborty, Bulbul; Freed, Denise E; O'Hern, Corey S

    2012-10-01

    We perform extensive molecular dynamics simulations of dense liquids composed of bidisperse dimer- and ellipse-shaped particles in two dimensions that interact via purely repulsive contact forces. We measure the structural relaxation times obtained from the long-time α decay of the self part of the intermediate scattering function for the translational and rotational degrees of freedom (DOF) as a function of packing fraction φ, temperature T, and aspect ratio α. We are able to collapse the packing-fraction and temperature-dependent structural relaxation times for disks, and dimers and ellipses over a wide range of α, onto a universal scaling function F(±)(|φ-φ(0)|,T,α), which is similar to that employed in previous studies of dense liquids composed of purely repulsive spherical particles in three dimensions. F(±) for both the translational and rotational DOF are characterized by the α-dependent scaling exponents μ and δ and packing fraction φ(0)(α) that signals the crossover in the scaling form F(±) from hard-particle dynamics to super-Arrhenius behavior for each aspect ratio. We find that the fragility of structural relaxation at φ(0), m(φ(0)), decreases monotonically with increasing aspect ratio for both ellipses and dimers. For α>α(p), where α(p) is the location of the peak in the packing fraction φ(J) at jamming onset, the rotational DOF are strongly coupled to the translational DOF, and the dynamic scaling exponents and φ(0) are similar for the rotational and translational DOF. For 1composed of dimer- and ellipse-shaped particles are qualitatively the same, despite the fact that zero-temperature static packings of dimers are isostatic, while static packings of ellipses are hypostatic. Thus, zero-temperature contact counting arguments do not apply to structural relaxation of dense liquids of anisotropic particles near the glass transition.

  9. Understanding the anisotropic ion distributions within magnetotail dipolarizing flux bundles

    Science.gov (United States)

    Zhou, X.; Runov, A.; Angelopoulos, V.; Birn, J.

    2017-12-01

    Dipolarizing flux bundles (DFBs), earthward-propagating structures with enhanced northward magnetic field (Bz) component, are usually believed to carry a different plasma population from that in the ambient magnetotail plasma sheet. The ion distribution functions within the DFB, however, are recently found to be largely controlled by the ion adiabaticity parameter κ in the ambient plasma sheet outside the DFBs. According to these observations, the ambient κ values of 2-3 usually correspond to a strong perpendicular anisotropy of suprathermal ions within the DFBs, whereas for lower κ values the ions inside the DFBs become more isotropic. Here we utilize a simple, test-particle model to explore the nature of the anisotropy and its dependence on the ambient κ values. We find that the ion anisotropy originates from successive ion reflections and reentries to the DFBs, during which the ions can be consecutively accelerated in the perpendicular direction by the DFB-carried electric field. This acceleration process may be interrupted, however, when the magnetic field lines are highly curved in the ambient plasma sheet. In this case, the ion trajectories are most stochastic outside the DFB region, which makes the reflected ions less likely to return to the DFBs for another cycle of acceleration; as a consequence, the perpendicular ion anisotropy does not appear. Given that the DFB ions are a free energy source for instabilities when they are injected towards Earth, our simple model (that reproduces most observational features on the anisotropic DFB ion distributions) may shed new lights on the coupling process between the magnetotail and the inner magneosphere.

  10. Anisotropic thermal expansion in a metal-organic framework.

    Science.gov (United States)

    Madsen, Solveig Røgild; Lock, Nina; Overgaard, Jacob; Iversen, Bo Brummerstedt

    2014-06-01

    Ionothermal reaction between Mn(II)(acetate)2·4H2O and 1,3,5-benzenetricarboxylic acid (H3BTC) in either of the two ionic liquids 1-ethyl-3-methylimidazolium bromide (EMIMBr) and 1-ethyl-3-methylimidazolium tosylate (EMIMOTs) resulted in the formation of the new metal-organic framework (MOF) EMIM[Mn(II)BTC] (BTC = 1,3,5-benzenetricarboxylate). The compound crystallizes in the orthorhombic space group Pbca with unit-cell parameters of a = 14.66658 (12), b = 12.39497 (9), c = 16.63509 (14) Å at 100 K. Multi-temperature single-crystal (15-340 K) and powder X-ray diffraction studies (100-400 K) reveal strongly anisotropic thermal expansion properties. The linear thermal expansion coefficients, αL(l), attain maximum values at 400 K along the a- and b-axis, with αL(a) = 115 × 10(-6) K(-1) and αL(b) = 75 × 10(-6) K(-1). At 400 K a negative thermal expansion coefficient of -40 × 10(-6) K(-1) is observed along the c-axis. The thermal expansion is coupled to a continuous deformation of the framework, which causes the structure to expand in two directions. Due to the rigidity of the linker, the expansion in the ab plane causes the network to contract along the c-axis. Hirshfeld surface analysis has been used to describe the interaction between the framework structure and the EMIM cation that resides within the channel. This reveals a number of rather weak interactions and one governing hydrogen-bonding interactions.

  11. Anisotropic Pauli Spin Blockade of Holes in a GaAs Double Quantum Dot

    Science.gov (United States)

    Wang, Qingwen; Klochan, Oleh; Hung, Jo-Tzu; Culcer, Dimitrie; Farrer, Ian; Ritchie, David; Hamilton, Alex

    Electrically defined semiconductor quantum dots are appealing systems for spin manipulation and quantum information processing. Thanks to the weak hyperfine interaction and the strong spin-orbit interaction, heavy-holes in GaAs are promising candidates for all-electrical spin manipulation. However, making stable quantum dots in GaAs has only become possible recently, mainly because of difficulties in device fabrication and device stability. Here we present electrical transport measurements of heavy-holes in a lateral double quantum dot based on a GaAs /AlxGa1 - x As heterostructure. We observe clear Pauli spin blockade and show that the lifting of the spin blockade by an external magnetic field is extremely anisotropic. Numerical calculations of heavy-hole transport through a double quantum dot in the presence of strong spin-orbit interaction demonstrate quantitative agreement with experimental results, which indicates that the observed anisotropy can be explained by the anisotropic hole g-factor and the surface Dresselhaus spin-orbit coupling.

  12. Quantum transport of atomic matter waves in anisotropic two-dimensional and three-dimensional disorder

    International Nuclear Information System (INIS)

    Piraud, M; Pezzé, L; Sanchez-Palencia, L

    2013-01-01

    The macroscopic transport properties in a disordered potential, namely diffusion and weak/strong localization, closely depend on the microscopic and statistical properties of the disorder itself. This dependence is rich in counter-intuitive consequences. It can be particularly exploited in matter wave experiments, where the disordered potential can be tailored and controlled, and anisotropies are naturally present. In this work, we apply a perturbative microscopic transport theory and the self-consistent theory of Anderson localization to study the transport properties of ultracold atoms in anisotropic two-dimensional (2D) and three-dimensional (3D) speckle potentials. In particular, we discuss the anisotropy of single-scattering, diffusion and localization. We also calculate disorder-induced shift of the energy states and propose a method to include it, which amounts to renormalizing energies in the standard on-shell approximation. We show that the renormalization of energies strongly affects the prediction for the 3D localization threshold (mobility edge). We illustrate the theoretical findings with examples which are relevant for current matter wave experiments, where the disorder is created with laser speckle. This paper provides a guideline for future experiments aiming at the precise location of the 3D mobility edge and study of anisotropic diffusion and localization effects in 2D and 3D. (paper)

  13. Polyvinylpyrrolidone-induced anisotropic growth of gold nanoprisms in plasmon-driven synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Yueming; DuChene, Joseph S.; Wang, Yi-Chung; Qiu, Jingjing; Johnston-Peck, Aaron C.; You, Bo; Guo, Wenxiao; DiCiaccio, Benedetto; Qian, Kun; Zhao, Evan W.; Ooi, Frances; Hu, Dehong; Su, Dong; Stach, Eric A.; Zhu, Zihua; Wei, Wei David

    2016-07-04

    After more than a decade, it is still unknown whether the plasmon-mediated growth of silver nanostructures can be extended to the synthesis of other noble metals, as the molecular mechanisms governing the growth process remain elusive. Herein, we demonstrate the plasmon-driven synthesis of gold nanoprisms and elucidate the details of the photochemical growth mechanism at the single-nanoparticle level. Our investigation reveals that the surfactant polyvinylpyrrolidone preferentially adsorbs along the nanoprism perimeter and serves as a photochemical relay to direct the anisotropic growth of gold nanoprisms. This discovery confers a unique function to polyvinylpyrrolidone that is fundamentally diferent from its widely accepted role as a crystal-face-blocking ligand. Additionally, we find that nanocrystal twinning exerts a profound influence on the kinetics of this photochemical process by controlling the transport of plasmon-generated hot electrons to polyvinylpyrrolidone. These insights establish a molecular-level description of the underlying mechanisms regulating the plasmon-driven synthesis of gold nanoprisms.

  14. Strong Coupling Holography

    CERN Document Server

    Dvali, Gia

    2009-01-01

    We show that whenever a 4-dimensional theory with N particle species emerges as a consistent low energy description of a 3-brane embedded in an asymptotically-flat (4+d)-dimensional space, the holographic scale of high-dimensional gravity sets the strong coupling scale of the 4D theory. This connection persists in the limit in which gravity can be consistently decoupled. We demonstrate this effect for orbifold planes, as well as for the solitonic branes and string theoretic D-branes. In all cases the emergence of a 4D strong coupling scale from bulk holography is a persistent phenomenon. The effect turns out to be insensitive even to such extreme deformations of the brane action that seemingly shield 4D theory from the bulk gravity effects. A well understood example of such deformation is given by large 4D Einstein term in the 3-brane action, which is known to suppress the strength of 5D gravity at short distances and change the 5D Newton's law into the four-dimensional one. Nevertheless, we observe that the ...

  15. Neutron scattering measurements of spatially anisotropic magnetic exchange interactions in semiconducting K0.85 Fe1.54Se2 (TN = 280 K.

    Science.gov (United States)

    Zhao, Jun; Shen, Yao; Birgeneau, R J; Gao, Miao; Lu, Zhong-Yi; Lee, D-H; Lu, X Z; Xiang, H J; Abernathy, D L; Zhao, Y

    2014-05-02

    We use neutron scattering to study the spin excitations associated with the stripe antiferromagnetic order in semiconducting K(0.85)Fe(1.54)Se(2) (T(N) = 280 K). We show that the spin-wave spectra can be accurately described by an effective Heisenberg Hamiltonian with highly anisotropic inplane couplings at T = 5 K. At high temperature (T = 300 K) above T(N), short-range magnetic correlation with anisotropic correlation lengths are observed. Our results suggest that, despite the dramatic difference in the Fermi surface topology, the inplane anisotropic magnetic couplings are a fundamental property of the iron-based compounds; this implies that their antiferromagnetism may originate from local strong correlation effects rather than weak coupling Fermi surface nesting.

  16. Study on the adsorption performance of composite adsorbent of CaCl2 and expanded graphite with ammonia as adsorbate

    International Nuclear Information System (INIS)

    Li, S.L.; Wu, J.Y.; Xia, Z.Z.; Wang, R.Z.

    2009-01-01

    A novel constant volume test unit was built to study the adsorption performance of a new type composite adsorbent. This test unit can measure the adsorption isosteres of the working pairs. The adsorption isosteres are the curves of the adsorption pressure variation with the adsorption temperatures at constant adsorption quantities. Compared to the former test results of isothermals and isobars, the isosteres are better for the calculation of the adsorption heat, desorption heat and the selection the adsorption working pairs. Three experimental results were obtained: the first result was that the expanded graphite powders were superior to the expandable graphite powders to facilitate the transportation of working fluid in the composite adsorbent. The second one was that the composite adsorbent treated by solution is more homogeneous than the simple mixed composite adsorbent and the treated composite adsorbent has a better mass transfer performance. The last one was that the adsorption isosteres was the same one not only in the heating process but also in the cooling process and this performance was not relevant to the homogeneity of the composite adsorbent

  17. Equilibrium, kinetic and sorber design studies on the adsorption of Aniline blue dye by sodium tetraborate-modified Kaolinite clay adsorbent.

    Science.gov (United States)

    Unuabonah, Emmanuel I; Adebowale, Kayode O; Dawodu, Folasegun A

    2008-09-15

    Raw Kaolinite clay obtained Ubulu-Ukwu, Delta State of Nigeria and its sodium tetraborate (NTB)-modified analogue was used to adsorb Aniline blue dye. Fourier transformed infrared spectra of NTB-modified Kaolinite suggests that modification was effective on the surface of the Kaolinite clay with the strong presence of inner -OH functional group. The modification of Kaolinite clay raised its adsorption capacity from 1666 to 2000 mg/kg. Modeling adsorption data obtained from both unmodified and NTB-modified Kaolinite clay reveals that the adsorption of Aniline blue dye on unmodified Kaolinite clay is on heterogeneous adsorption sites because it followed strongly the Freundlich isotherm equation model while adsorption data from NTB-modified Kaolinite clay followed strongly the Langmuir isotherm equation model which suggest that Aniline blue dye was adsorb homogeneous adsorption sites on the NTB-modified adsorbent surface. There was an observed increase in the amount of Aniline blue adsorbed as initial dye concentration was increased from 10 to 30 mg/L. It was observed that kinetic data obtained generally gave better robust fit to the second-order kinetic model (SOM). The initial sorption rate was found to increased with increasing initial dye concentration (from 10 to 20 mg/L) for data obtained from 909 to 1111 mg kg(-1)min(-1) for unmodified and 3325-5000 mg kg(-1) min(-1) for NTB-modified adsorbents. Thereafter there was a decrease in initial sorption rate with further increase in dye concentration. The linearity of the plots of the pseudo-second-order model with very high-correlation coefficients indicates that chemisorption is involved in the adsorption process. From the design of a single-batch adsorber it is predicted that the NTB-modified Kaolinite clay adsorbent will require 50% less of the adsorbent to treat certain volumes of wastewater containing 30 mg/L of Aniline blue dye when it is compared with the unmodified adsorbent. This will be cost effective in

  18. LIGO: The strong belief

    CERN Multimedia

    Antonella Del Rosso

    2016-01-01

    Twenty years of designing, building and testing a number of innovative technologies, with the strong belief that the endeavour would lead to a historic breakthrough. The Bulletin publishes an abstract of the Courier’s interview with Barry Barish, one of the founding fathers of LIGO.   The plots show the signals of gravitational waves detected by the twin LIGO observatories at Livingston, Louisiana, and Hanford, Washington. (Image: Caltech/MIT/LIGO Lab) On 11 February, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations published a historic paper in which they showed a gravitational signal emitted by the merger of two black holes. These results come after 20 years of hard work by a large collaboration of scientists operating the two LIGO observatories in the US. Barry Barish, Linde Professor of Physics, Emeritus at the California Institute of Technology and former Director of the Global Design Effort for the Internat...

  19. Intramolecular charge separation in spirobifluorene-based donor–acceptor compounds adsorbed on Au and indium tin oxide electrodes

    International Nuclear Information System (INIS)

    Heredia, Daniel; Otero, Luis; Gervaldo, Miguel; Fungo, Fernando; Dittrich, Thomas; Lin, Chih-Yen; Chi, Liang-Chen; Fang, Fu-Chuan; Wong, Ken-Tsung

    2013-01-01

    Surface photovoltage (SPV) measurements were performed with a Kelvin-probe in spirobifluorene-based donor (diphenylamine)–acceptor (dicyano or cyanoacrylic acid moieties) compounds adsorbed from highly diluted solutions onto Au and indium tin oxide electrode surfaces. Strong intramolecular charge separation (negative SPV signals up to more than 0.1 V) due to directed molecule adsorption was observed only for spirobifluorene donor–acceptor compounds with carboxylic acid moiety. SPV signals and onset energies of electronic transitions depended on ambience conditions. - Highlights: ► Fluorene donor–acceptor derivatives were adsorbed at Au and indium tin oxide. ► Surface photovoltage measurements were performed with a Kelvin-probe. ► Strong intra-molecular charge separation was observed. ► SPV signals depended on ambience conditions

  20. Characterisation of phase transition in adsorbed monolayers at the air/water interface.

    Science.gov (United States)

    Vollhardt, D; Fainerman, V B

    2010-02-26

    Recent work has provided experimental and theoretical evidence that a first order fluid/condensed (LE/LC) phase transition can occur in adsorbed monolayers of amphiphiles and surfactants which are dissolved in aqueous solution. Similar to Langmuir monolayers, also in the case of adsorbed monolayers, the existence of a G/LE phase transition, as assumed by several authors, is a matter of question. Representative studies, at first performed with a tailored amphiphile and later with numerous other amphiphiles, also with n-dodecanol, provide insight into the main characteristics of the adsorbed monolayer during the adsorption kinetics. The general conditions necessary for the formation of a two-phase coexistence in adsorbed monolayers can be optimally studied using dynamic surface pressure measurements, Brewster angle microscopy (BAM) and synchrotron X-ray diffraction at grazing incidence (GIXD). A characteristic break point in the time dependence of the adsorption kinetics curves indicates the phase transition which is largely affected by the concentration of the amphiphile in the aqueous solution and on the temperature. Formation and growth of condensed phase domains after the phase transition point are visualised by BAM. As demonstrated by a tailored amphiphile, various types of morphological textures of the condensed phase can occur in different temperature regions. Lattice structure and tilt angle of the alkyl chains in the condensed phase of the adsorbed monolayer are determined using GIXD. The main growth directions of the condensed phase textures are correlated with the two-dimensional lattice structure. The results, obtained for the characteristics of the condensed phase after a first order main transition, are supported by experimental bridging to the Langmuir monolayers. Phase transition of adsorbing trace impurities in model surfactants can strongly affect the characteristics of the main component. Dodecanol present as minor component in aqueous sodium

  1. Structural and magnetic studies on heavy-metal-adsorbing iron sulphide nanoparticles produced by sulphate-reducing bacteria

    International Nuclear Information System (INIS)

    Watson, J.H.P; Cressey, B.A.; Roberts, A.P.; Ellwood, D.C.; Charnock, J.M.; Soper, A.K.

    2000-01-01

    In previous and in work to be published, it has been shown that iron sulphide material, produced by sulphate-reducing bacteria (SRB), is an excellent adsorbent for a wide range of heavy metals. The material adsorbs between 100 and 400 mg g -1 and residual levels in solutions can be of the order of pg per litre. Further, strongly magnetic forms of this material can now be produced which can be effectively and cheaply removed from suspension together with the adsorbate by magnetic separation. This paper examines the structure of weakly magnetic and strongly magnetic iron sulphide material produced by SRB with a view to increasing the understanding of its adsorbent and the magnetic properties. The structural properties have been examined using high-resolution imaging and electron diffraction in a transmission electron microscope (TEM), the measurements of magnetisation versus field and temperature, extended X-ray absorption fine-structure (EXAFS) spectroscopy, X-ray absorption near-edge structure (XANES) spectroscopy and neutron diffraction. Before drying the surface area of both the weakly magnetic and the strongly magnetic iron sulphide is of the order of 400-500 m 2 g -1 as revealed by the magnetic properties, neutron scattering and the adsorption of a number of heavy metals. After freeze-drying the surface area falls to between 18 and 19 m 2 g -1 . The initial inocula came from a semi-saline source and when fed with nutrient containing Fe 2+ and Fe 3+ produced a weakly magnetic iron sulphide (Watson et al., Minerals Eng. 8 (1995) 1097) and a few % of a more strongly magnetic material. Further work using a novel method (Keller-Besrest, Collin, J. Solid State Chem. 84 (1990) 211) produced a strongly magnetic iron sulphide material. EXAFS and XANES spectroscopy revealed (Keller-Besrest and Collin, 1990) that the weakly magnetic iron sulphide material had the Ni-As structure in which the Fe is tetrahedrally coordinated with the composition Fe 1-x S. The strongly

  2. Ultrafast quantum beats of anisotropic excitons in atomically thin ReS2.

    Science.gov (United States)

    Sim, Sangwan; Lee, Doeon; Trifonov, Artur V; Kim, Taeyoung; Cha, Soonyoung; Sung, Ji Ho; Cho, Sungjun; Shim, Wooyoung; Jo, Moon-Ho; Choi, Hyunyong

    2018-01-24

    Quantum beats, periodic oscillations arising from coherent superposition states, have enabled exploration of novel coherent phenomena. Originating from strong Coulomb interactions and reduced dielectric screening, two-dimensional transition metal dichalcogenides exhibit strongly bound excitons either in a single structure or hetero-counterpart; however, quantum coherence between excitons is barely known to date. Here we observe exciton quantum beats in atomically thin ReS 2 and further modulate the intensity of the quantum beats signal. Surprisingly, linearly polarized excitons behave like a coherently coupled three-level system exhibiting quantum beats, even though they exhibit anisotropic exciton orientations and optical selection rules. Theoretical studies are also provided to clarify that the observed quantum beats originate from pure quantum coherence, not from classical interference. Furthermore, we modulate on/off quantum beats only by laser polarization. This work provides an ideal laboratory toward polarization-controlled exciton quantum beats in two-dimensional materials.

  3. Micromechanics model for predicting anisotropic electrical conductivity of carbon fiber composite materials

    Science.gov (United States)

    Haider, Mohammad Faisal; Haider, Md. Mushfique; Yasmeen, Farzana

    2016-07-01

    Heterogeneous materials, such as composites consist of clearly distinguishable constituents (or phases) that show different electrical properties. Multifunctional composites have anisotropic electrical properties that can be tailored for a particular application. The effective anisotropic electrical conductivity of composites is strongly affected by many parameters including volume fractions, distributions, and orientations of constituents. Given the electrical properties of the constituents, one important goal of micromechanics of materials consists of predicting electrical response of the heterogeneous material on the basis of the geometries and properties of the individual phases, a task known as homogenization. The benefit of homogenization is that the behavior of a heterogeneous material can be determined without resorting or testing it. Furthermore, continuum micromechanics can predict the full multi-axial properties and responses of inhomogeneous materials, which are anisotropic in nature. Effective electrical conductivity estimation is performed by using classical micromechanics techniques (composite cylinder assemblage method) that investigates the effect of the fiber/matrix electrical properties and their volume fractions on the micro scale composite response. The composite cylinder assemblage method (CCM) is an analytical theory that is based on the assumption that composites are in a state of periodic structure. The CCM was developed to extend capabilities variable fiber shape/array availability with same volume fraction, interphase analysis, etc. The CCM is a continuum-based micromechanics model that provides closed form expressions for upper level length scales such as macro-scale composite responses in terms of the properties, shapes, orientations and constituent distributions at lower length levels such as the micro-scale.

  4. New Insight of Northern Apennines (Italy): SKS Splitting Measurements Reveal a Complex Anisotropic Structure

    Science.gov (United States)

    Salimbeni, S.; Pondrelli, S.; Margheriti, L.; Levin, V.; Park, J.; Plomerova, J.

    2006-12-01

    The multidisciplinary RETREAT project (REtreating-Trench, Extension and Accretion Tectonics) is focused on the development of a 3D self-consistent dynamic model of the syn-convergent extension in the Northern Apennines. The seismological deployment of the Project started on 2003 and closed on September 2006, using 10 instruments lent by the GFU and 25 instruments lent by PASSCAL, added to the permanent stations of the Italian National Network. Many of the stations were deployed along a NE-SW transect across the Apennine chain. We present here new results of seismic anisotropy analysis obtained from SKS core-refracted shear waves. The study of SKS splitting is applied on twenty teleseismic earthquakes; for all of them we calculate the anisotropic parameters (delay time and fast polarization direction) by minimizing the energy in the transverse component. Our analysis assesses uncertainty by testing the parameters for stability to noise. Previous studies of splitting analysis have found in the study region evidence for tectonic domains in which a coherent splitting signal can be found. The Tuscany domain (Tyrrhenian side) shows homogeneous NW-SE fast axes directions; the Po-Plain domain (Eastern side of the Apennines) shows a N-S to NE-SW directions, here strongly influenced by backazimuth. To better define the complex structure that may exist below the Northern Apennines and Po Plain we apply the cross convolution method of Menke and Levin (2003) to discriminate whether a two-layer anisotropic model fits the splitting pattern more convincingly that a simple one-layer model. Previous analysis suggested that structure beneath the Tuscany side is simpler; a single anisotropic layer with a NW-SE fast polarization direction is in agreement with all the dataset. Beneath the Po Plain the complexity of the structure is confirmed in the analysis of most stations.

  5. John Strong (1941 - 2006)

    CERN Multimedia

    Wickens, F

    Our friend and colleague John Strong was cruelly taken from us by a brain tumour on Monday 31st July, a few days before his 65th birthday John started his career working with a group from Westfield College, under the leadership of Ted Bellamy. He obtained his PhD and spent the early part of his career on experiments at Rutherford Appleton Laboratory (RAL), but after the early 1970s his research was focussed on experiments in CERN. Over the years he made a number of notable contributions to experiments in CERN: The Omega spectrometer adopted a system John had originally developed for experiments at RAL using vidicon cameras to record the sparks in the spark chambers; He contributed to the success of NA1 and NA7, where he became heavily involved in the electronic trigger systems; He was responsible for the second level trigger system for the ALEPH detector and spent five years leading a team that designed and built the system, which ran for twelve years with only minor interventions. Following ALEPH he tur...

  6. Stirring Strongly Coupled Plasma

    CERN Document Server

    Fadafan, Kazem Bitaghsir; Rajagopal, Krishna; Wiedemann, Urs Achim

    2009-01-01

    We determine the energy it takes to move a test quark along a circle of radius L with angular frequency w through the strongly coupled plasma of N=4 supersymmetric Yang-Mills (SYM) theory. We find that for most values of L and w the energy deposited by stirring the plasma in this way is governed either by the drag force acting on a test quark moving through the plasma in a straight line with speed v=Lw or by the energy radiated by a quark in circular motion in the absence of any plasma, whichever is larger. There is a continuous crossover from the drag-dominated regime to the radiation-dominated regime. In the crossover regime we find evidence for significant destructive interference between energy loss due to drag and that due to radiation as if in vacuum. The rotating quark thus serves as a model system in which the relative strength of, and interplay between, two different mechanisms of parton energy loss is accessible via a controlled classical gravity calculation. We close by speculating on the implicati...

  7. Strong-interaction nonuniversality

    International Nuclear Information System (INIS)

    Volkas, R.R.; Foot, R.; He, X.; Joshi, G.C.

    1989-01-01

    The universal QCD color theory is extended to an SU(3) 1 direct product SU(3) 2 direct product SU(3) 3 gauge theory, where quarks of the ith generation transform as triplets under SU(3)/sub i/ and singlets under the other two factors. The usual color group is then identified with the diagonal subgroup, which remains exact after symmetry breaking. The gauge bosons associated with the 16 broken generators then form two massive octets under ordinary color. The interactions between quarks and these heavy gluonlike particles are explicitly nonuniversal and thus an exploration of their physical implications allows us to shed light on the fundamental issue of strong-interaction universality. Nonuniversality and weak flavor mixing are shown to generate heavy-gluon-induced flavor-changing neutral currents. The phenomenology of these processes is studied, as they provide the major experimental constraint on the extended theory. Three symmetry-breaking scenarios are presented. The first has color breaking occurring at the weak scale, while the second and third divorce the two scales. The third model has the interesting feature of radiatively induced off-diagonal Kobayashi-Maskawa matrix elements

  8. Neutron activation analysis for the characterization of seawater uranium adsorbents.

    Science.gov (United States)

    Byers, M; Landsberger, S; Schneider, E; Eder, S

    2018-03-01

    This work details the development of an iterative neutron activation analysis (NAA) based workflow to precisely quantify metal ion uptake in an adsorbent. The workflow is iterative because it explores the dependence between independent variables defining the adsorbent fabrication procedure and the time-dependent uptake. It can be adapted to other adsorbents provided they have an affinity for ions which are amenable to efficient quantification using NAA. For this work, the ability of silver nanoparticles to mitigate the negative effects of biofouling on uranium transfer to an adsorbent was ultimately of interest, and hence motivates the development of this method. The limits of U detection and quantification were found to be 0.609 and 3.01μgg -1 , respectively; these were obtained using modest irradiation and counting times. The uncertainties arising from the NAA procedure were no more than 9.9%, far smaller than other sources of uncertainty present in the analysis. These results provided solid evidence that adsorbent shape and structure, rather than uniformity of composition, drives variability in adsorption of uranium. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Recycling Spent Cr Adsorbents as Catalyst for Eliminating Methylmercaptan.

    Science.gov (United States)

    He, Dedong; Zhang, Liming; Zhao, Yutong; Mei, Yi; Chen, Dingkai; He, Sufang; Luo, Yongming

    2018-03-20

    Waste adsorbents generated from treating Cr(VI)-containing wastewater are hazardous materials and generally landfilled or treated by acid or base desorption, with concomitant high cost and toxic effects. The present work shows that these Cr adsorbents can be reused as highly efficient catalysts for treating sulfur-containing VOCs (CH 3 SH), not only avoiding the economic and environmental impact from the conventional approaches, but also achieving the efficient treatment of sulfur-containing waste gas. Importantly, these reused Cr adsorbents exhibit enhanced activity and stability compared with the catalysts reported elsewhere, indicating a new avenue of green chemistry. The highly toxic adsorbed Cr(VI) species are reduced to a Cr 2 O 3 crystalline phase by calcination and finally immobilized as a Cr 2 S 3 solid phase while converting and eliminating CH 3 SH. Still, the presence of Cr(VI) species on the reused Cr adsorbent provides enough reactive sites for reaction, but high concentration of Cr(VI) species causes serious accumulation of coke deposit on the catalyst, leading to fast deactivation of the catalyst.

  10. Lipid monolayers and adsorbed polyelectrolytes with different degrees of polymerization.

    Science.gov (United States)

    Ortmann, Thomas; Ahrens, Heiko; Lawrenz, Frank; Gröning, Andreas; Nestler, Peter; Günther, Jens-Uwe; Helm, Christiane A

    2014-06-17

    Polystyrene sulfonate (PSS) of different molecular weight M(w) is adsorbed to oppositely charged DODAB monolayers from dilute solutions (0.01 mmol/L). PSS adsorbs flatly in a lamellar manner, as is shown by X-ray reflectivity and grazing incidence diffraction (exception: PSS with M(w) below 7 kDa adsorbs flatly disordered to the liquid expanded phase). The surface coverage and the separation of the PSS chains are independent of PSS M(w). On monolayer compression, the surface charge density increases by a factor of 2, and the separation of the PSS chains decreases by the same factor. Isotherms show that on increase of PSS M(w) the transition pressure of the LE/LC (liquid expanded/liquid condensed) phase transition decreases. When the contour length exceeds the persistence length (21 nm), the transition pressure is low and constant. For low-M(w) PSS (<7 kDa) the LE/LC transition of the lipids and the disordered/ordered transition of adsorbed PSS occur simultaneously, leading to a maximum in the contour length dependence of the transition enthalpy. These findings show that lipid monolayers at the air/water interface are a suitable model substrate with adjustable surface charge density to study the equilibrium conformation of adsorbed polyelectrolytes as well as their interactions with a model membrane.

  11. Bio-polishing sludge adsorbents for dye removal

    Directory of Open Access Journals (Sweden)

    Zaini Muhammad Abbas Ahmad

    2016-12-01

    Full Text Available The objective of this work is to evaluate the removal of methylene blue dye by bio-polishing sludge-based adsorbents. The adsorbents were characterized according to the specific surface area, pH upon the treatment and surface functional groups. The adsorption of dye was carried out at room temperature, and the adsorption data were analyzed using the isotherm and kinetics models. The bio-polishing sludge is rich in ash content, and the presence of surface functional groups varied with the treatment strategies. The specific surface area of adsorbents is between 7.25 and 20.8 m2/g. Results show that the maximum removal of methylene blue by sludge adsorbents was observed to have the following order: untreated sludge (SR > zinc chloride-treated (SZ > microwave-dried (SW = potassium carbonate-treated (SK > acid-washed (SH. The maximum adsorption capacities for SR and SZ as predicted by the Langmuir model are 170 and 135 mg/g, respectively. Although SR demonstrates a higher maximum removal than SZ, the latter exhibits greater removal intensity and rate constant even at high dye concentration. The bio-polishing sludge is a promising adsorbent for dye wastewater treatment.

  12. Development of nanohybrid adsorbent for defluoridation from aqueous systems.

    Science.gov (United States)

    Dhongde, Vicky; Wasewar, Kailas L; De, Biswajit S

    2017-12-01

    The objective of present study is advancement of an efficient nanomaterial which was investigated to substantiate its efficiency, using kinetic studies to ensnare fluoride in order to make water potable. A new crystalline ZrAlCa nanohybrid adsorbent for fluoride removal was successfully synthesized by a co-precipitation method in this study. The prepared adsorbents were characterized by XRD, FT-IR, TGA, BET and FESEM and EDX. The adsorption properties of the developed adsorbent were studied using batch adsorption method which shown the noticeable fluoride removal efficiency up to 99% at near neutral pH as well as in acidic pH range. The reaction kinetics for adsorption of fluoride was established using reaction based kinetic models which fitted well with Avarami kinetic model as compared to pseudo-first-order, pseudo second-order and power function rate expression. The equilibrium isotherm modelling described adsorption process and Langmuir, Jovanovic, Temkin and Freundlich isotherms provides best fit to experimental data. The fluoride loaded adsorbent was efficiently regenerated by using an alkali solution and has no significant counter ion effect on fluoride adsorption efficiency. Interestingly, the developed nanomaterial has fluoride removal efficacy over varied concentration ranges. It has capability of reanimate and reuse the nanohybrid adsorbent makes it an attractive sustainable material. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Adsorption behavior of lithium from seawater using manganese oxide adsorbent

    International Nuclear Information System (INIS)

    Wajima, Takaaki; Munakata, Kenzo; Uda, Tatsuhiko

    2012-01-01

    The deuterium-tritium (D-T) fusion reactor system is expected to provide the main source of electricity in the future. Large amounts of lithium will be required, dependent on the reactor design concept, and alternative resources should be found to provide lithium inventories for nuclear fusion plants. Seawater has recently become an attractive source of this element and the separation and recovery of lithium from seawater by co-precipitation, solvent extraction and adsorption have been investigated. Amongst these techniques, the adsorption method is suitable for recovery of lithium from seawater, because certain inorganic ion-exchange materials, especially spinel-type manganese oxides, show extremely high selectivity for the lithium ion. In this study, we prepared a lithium adsorbent (HMn 2 O 4 ) by elution of spinel-type lithium di-manganese-tetra-oxide (LiMn 2 O 4 ) and examined the kinetics of the adsorbent for lithium ions in seawater using a pseudo-second-order kinetic model. The intermediate, LiMn 2 O 4 , can be synthesized from LiOH·H 2 O and Mn 3 O 4 , from which the lithium adsorbent can subsequently be prepared via acid treatment., The adsorption kinetics become faster and the amount of lithium adsorbed on the adsorbent increases with increasing solution temperature. The thermodynamic values, ΔG 0 , ΔH 0 and ΔS 0 , indicate that adsorption is an endothermic and spontaneous process. (author)

  14. Microporous carbonaceous adsorbents for CO2 separation via selective adsorption

    KAUST Repository

    Zhao, Yunfeng

    2015-01-01

    Selective adsorption of CO2 has important implications for many energy and environment-related processes, which require the separation of CO2 from other gases (e.g. N2 and CH4) with high uptakes and selectivity. The development of high-performance adsorbents is one of the most promising solutions to the success of these processes. The present review is focused on the state-of-the-art of carbon-based (carbonaceous) adsorbents, covering microporous inorganic carbons and microporous organic polymers, with emphasis on the correlation between their textural and compositional properties and their CO2 adsorption/separation performance. Special attention is given to the most recently developed materials that were not covered in previous reviews. We summarize various effective strategies (N-doping, surface functionalization, extra-framework ions, molecular design, and pore size engineering) for enhancing the CO2 adsorption capacity and selectivity of carbonaceous adsorbents. Our discussion focuses on CO2/N2 separation and CO2/CH4 separation, while including an introduction to the methods and criteria used for evaluating the performance of the adsorbents. Critical issues and challenges regarding the development of high-performance adsorbents as well as some overlooked facts and misconceptions are also discussed, with the aim of providing important insights into the design of novel carbonaceous porous materials for various selective adsorption based applications. This journal is © The Royal Society of Chemistry.

  15. 3-D waveform tomography sensitivity kernels for anisotropic media

    KAUST Repository

    Djebbi, Ramzi

    2014-01-01

    The complications in anisotropic multi-parameter inversion lie in the trade-off between the different anisotropy parameters. We compute the tomographic waveform sensitivity kernels for a VTI acoustic medium perturbation as a tool to investigate this ambiguity between the different parameters. We use dynamic ray tracing to efficiently handle the expensive computational cost for 3-D anisotropic models. Ray tracing provides also the ray direction information necessary for conditioning the sensitivity kernels to handle anisotropy. The NMO velocity and η parameter kernels showed a maximum sensitivity for diving waves which results in a relevant choice of those parameters in wave equation tomography. The δ parameter kernel showed zero sensitivity; therefore it can serve as a secondary parameter to fit the amplitude in the acoustic anisotropic inversion. Considering the limited penetration depth of diving waves, migration velocity analysis based kernels are introduced to fix the depth ambiguity with reflections and compute sensitivity maps in the deeper parts of the model.

  16. Anomalously large anisotropic magnetoresistance in a perovskite manganite.

    Science.gov (United States)

    Li, Run-Wei; Wang, Huabing; Wang, Xuewen; Yu, X Z; Matsui, Y; Cheng, Zhao-Hua; Shen, Bao-Gen; Plummer, E Ward; Zhang, Jiandi

    2009-08-25

    The signature of correlated electron materials (CEMs) is the coupling between spin, charge, orbital and lattice resulting in exotic functionality. This complexity is directly responsible for their tunability. We demonstrate here that the broken symmetry, through cubic to orthorhombic distortion in the lattice structure in a prototype manganite single crystal, La(0.69)Ca(0.31)MnO(3), leads to an anisotropic magneto-elastic response to an external field, and consequently to remarkable magneto-transport behavior. An anomalous anisotropic magnetoresistance (AMR) effect occurs close to the metal-insulator transition (MIT) in the system, showing a direct correlation with the anisotropic field-tuned MIT in the system and can be understood by means of a simple phenomenological model. A small crystalline anisotropy stimulates a "colossal" AMR near the MIT phase boundary of the system, thus revealing the intimate interplay between magneto- and electronic-crystalline couplings.

  17. Electromagnetic waves in uniaxial anisotropic chiral waveguides in magnetized plasma

    Science.gov (United States)

    Ghaffar, A.; Alkanhal, Majeed A. S.

    2015-07-01

    The characteristics of guided modes in circular waveguides of a uniaxial anisotropic chiral core and a cladding filled with anisotropic plasma are presented. The cladding region is assumed to be infinitely extended with an external applied magnetic field oriented along the direction of propagation in the waveguide. The characteristics equation for the modes in this waveguide are obtained. The variations of the propagation properties with the plasma parameters, chiral parameters, and the cyclotron frequency of plasma have been investigated. Particularly, the effects of the chirality and the cyclotron frequency of plasma on the magnitude and orientation of the energy flux of the guided modes for three kinds of uniaxial anisotropic chiral media have been numerically investigated. Comparisons of the computed results of the presented formulations with published results for some special cases confirm the accuracy of the presented analyses.

  18. Detection of the default mode network by an anisotropic analysis

    Science.gov (United States)

    Forero, Aura; Romero, Eduardo

    2017-11-01

    This document presents a proposal devoted to improve the detection of the default mode network (DMN) in resting state functional magnetic resonance imaging in noisy conditions caused by head movement. The proposed approach is inspired by the hierarchical treatment of information, in particular at the level of the brain basal ganglia. Essentially, the fact that information must be selected and reduced suggests propagation of information in the Central Nervous System (CNS) is anisotropic. Under this hypothesis, the reconstruction of information of activation should follow an anisotropic pattern. In this work, an anisotropic filter is used to recover the DMN that is perturbed by simulated motion artifacts. Results obtained show this approach outperforms the state-of-the-art methods by 5.93% PSNR.

  19. Anisotropic spreading of liquid metal on a rough intermetallic surface

    Directory of Open Access Journals (Sweden)

    Liu Wen

    2011-01-01

    Full Text Available An anisotropic wicking of molten Sn-Pb solder over an intermetallic rough surface has been studied. The phenomenon features preferential spreading and forming of an elliptical spread domain. A theoretically formulated model was established to predict the ratio of the wicking distance along the long axis (rx to that along the short axis (ry of the final wicking pattern. The phenomenon was simultaneously experimentally observed and recorded with a hotstage microscopy technique. The anisotropic wicking is established to be caused by a non-uniform topography of surface micro structures as opposed to an isotropic wicking on an intermetallic surface with uniformly distributed surface micro features. The relative deviation between the theoretically predicted rx/ry ratio and the corresponding average experimental value is 5%. Hence, the small margin of error confirms the validity of the proposed theoretical model of anisotropic wicking.

  20. Investigation of anisotropic scattering for optical tomography in biological tissues

    International Nuclear Information System (INIS)

    Mercimek, M.; Yildirim, H.; Geckinli, M.; Aydin, M.; Aydin, E. D.

    2009-01-01

    Photons with wavelengths in near infrared region are used in optical tomography. Radiation transport theory should be preferred instead of diffusion theory for numerical modelling of photon migration in biological tissues, where diffusion theory is invalid. For example, diffusion theory is not sufficient in the regions of close to boundaries, sources or sinks and highly absorbing or void-like media. Also anisotropic scattering must be considered in the numerical models since scattering is generally highly anisotropic in biological tissues. In addition to the absorption and scattering coefficients, a suitable phase function must be known in anisotropic scattering study. Here we have compared scattering phase functions for anisotropy. Then we have calculated Legendre moments which are necessary for the implementation of anisotropy factors into the transport code, PARTISN. Discrete ordinates method (SN) has been used in the transport calculations. We have obtained solutions first a homogeneous and then heterogeneous medium.

  1. Anomalously large anisotropic magnetoresistance in a perovskite manganite

    Science.gov (United States)

    Li, Run-Wei; Wang, Huabing; Wang, Xuewen; Yu, X. Z.; Matsui, Y.; Cheng, Zhao-Hua; Shen, Bao-Gen; Plummer, E. Ward; Zhang, Jiandi

    2009-01-01

    The signature of correlated electron materials (CEMs) is the coupling between spin, charge, orbital and lattice resulting in exotic functionality. This complexity is directly responsible for their tunability. We demonstrate here that the broken symmetry, through cubic to orthorhombic distortion in the lattice structure in a prototype manganite single crystal, La0.69Ca0.31MnO3, leads to an anisotropic magneto-elastic response to an external field, and consequently to remarkable magneto-transport behavior. An anomalous anisotropic magnetoresistance (AMR) effect occurs close to the metal-insulator transition (MIT) in the system, showing a direct correlation with the anisotropic field-tuned MIT in the system and can be understood by means of a simple phenomenological model. A small crystalline anisotropy stimulates a “colossal” AMR near the MIT phase boundary of the system, thus revealing the intimate interplay between magneto- and electronic-crystalline couplings. PMID:19706504

  2. Nonlinear, anisotropic, and giant photoconductivity in intrinsic and doped graphene

    Science.gov (United States)

    Singh, Ashutosh; Ghosh, Saikat; Agarwal, Amit

    2018-01-01

    We present a framework to calculate the anisotropic and nonlinear photoconductivity for two band systems with application to graphene. In contrast to the usual perturbative (second order in the optical field strength) techniques, we calculate photoconductivity to all orders in the optical field strength. In particular, for graphene, we find the photoresponse to be giant (at large optical field strengths) and anisotropic. The anisotropic photoresponse in graphene is correlated with polarization of the incident field, with the response being similar to that of a half-wave plate. We predict that the anisotropy in the simultaneous measurement of longitudinal (σx x) and transverse (σy x) photoconductivity, with four probes, offers a unique experimental signature of the photovoltaic response, distinguishing it from the thermal-Seebeck and bolometric effects in photoresponse.

  3. Modeling of charged anisotropic compact stars in general relativity

    Energy Technology Data Exchange (ETDEWEB)

    Dayanandan, Baiju; Maurya, S.K.; T, Smitha T. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman)

    2017-06-15

    A charged compact star model has been determined for anisotropic fluid distribution. We have solved the Einstein-Maxwell field equations to construct the charged compact star model by using the radial pressure, the metric function e{sup λ} and the electric charge function. The generic charged anisotropic solution is verified by exploring different physical conditions like causality condition, mass-radius relation and stability of the solution (via the adiabatic index, TOV equations and the Herrera cracking concept). It is observed that the present charged anisotropic compact star model is compatible with the star PSR 1937+21. Moreover, we also presented the EOS ρ = f(p) for the present charged compact star model. (orig.)

  4. Anisotropic turbulence and zonal jets in rotating flows with a β-effect

    Directory of Open Access Journals (Sweden)

    B. Galperin

    2006-01-01

    Full Text Available Numerical studies of small-scale forced, two-dimensional turbulent flows on the surface of a rotating sphere have revealed strong large-scale anisotropization that culminates in the emergence of quasi-steady sets of alternating zonal jets, or zonation. The kinetic energy spectrum of such flows also becomes strongly anisotropic. For the zonal modes, a steep spectral distribution, E(n=CZ (Ω/R2 n-5, is established, where CZ=O(1 is a non-dimensional coefficient, Ω is the angular velocity, and R is the radius of the sphere, respectively. For other, non-zonal modes, the classical, Kolmogorov-Batchelor-Kraichnan, spectral law is preserved. This flow regime, referred to as a zonostrophic regime, appears to have wide applicability to large-scale planetary and terrestrial circulations as long as those are characterized by strong rotation, vertically stable stratification and small Burger numbers. The well-known manifestations of this regime are the banded disks of the outer planets of our Solar System. Relatively less known examples are systems of narrow, subsurface, alternating zonal jets throughout all major oceans discovered in state-of-the-art, eddy-permitting simulations of the general oceanic circulation. Furthermore, laboratory experiments recently conducted using the Coriolis turntable have basically confirmed that the lateral gradient of ''planetary vorticity'' (emulated via the topographic β-effect is the primary cause of the zonation and that the latter is entwined with the development of the strongly anisotropic kinetic energy spectrum that tends to attain the same zonal and non-zonal distributions, −5 and , respectively, in both the slope and the magnitude, as the corresponding spectra in other environmental conditions. The non-dimensional coefficient CZ in the −5 spectral law appears to be invariant, , in a variety of simulated and natural flows. This paper provides a brief review of the zonostrophic regime. The review includes the

  5. Morphology of self assembled monolayers using liquid phase reaction on silica and their effect on the morphology of adsorbed insulin

    Science.gov (United States)

    Sharma, Indu; Pattanayek, Sudip K.; Aggarwal, Varsha; Ghosh, Subhasis

    2017-05-01

    The effect of roughness of two different categories of self-assembled monolayers (SAMs) with propyl amine and propyl groups respectively on the morphology of adsorbed insulin is observed. SAMs are obtained by liquid phase reaction of silica with organo silane coupling agents (SCA). The influence of the morphology and physical characteristics of the SAMs on the reaction time and concentration of the modifiers are explored. We have tested three SCA containing propyl amine with varying groups linked to Si present on it. In addition, we have used a silane coupling agent to prepare SAM of methyl head group. The approach of these molecules towards the surface depends on the head group and the groups linked to Si of the SCA. The morphology of the surfaces is analysed using power spectral density distribution (PSD), skewness, ellipsometry thickness and surface energy. Both chemical nature and physical morphology of the adsorbent influence the morphology of the adsorbed insulin. In general, a low number of aggregates of big size are formed on the surfaces obtained from low concentration of SAMs, while a higher number but of smaller size of aggregates are formed over surfaces obtained from 1% concentration of SAMs modifiers. The peak to valley ratio of the aggregates of insulin is strongly influenced by the size of grains of SCA over the adsorbent.

  6. Reflectance difference spectroscopy (RDS) investigation of ordering processes and phase transitions in adsorbate layers on Cu(110)

    International Nuclear Information System (INIS)

    Hohage, M.; Sun, L.D.; Zeppenfeld, P.; Balderas, R.; Hingerl, K.

    2002-01-01

    Full text: We present an RDS investigation of the behavior of adsorbate layers on Cu(110). RDS measures the difference in the optical reflectivity at normal incidence for light polarized in two orthogonal directions. In the case of fcc crystals like Cu the isotropic bulk has no contribution to the signal. Only symmetry breaking surfaces generate an optical anisotropy and thus a RDS response. The anisotropy signal of Cu(110) is strongly altered by the adsorption of molecules like oxygen and CO. The RDS signal depends not only on the species and coverage of the adsorbate, but is also extremely sensitive to the arrangement of the molecules within the layer. Disorder-order transitions and transformations between different superstructures and reconstructions are monitored in dependence of coverage and temperature. STM and diffraction techniques are used as complementary methods to further characterize the sample. It is shown that RDS is, indeed, an extremely sensitive method to study coverage or temperature driven structural changes of adsorbate layers as well as of adsorbate induced changes of the substrate surface. In the case of CO adsorption structural changes occur within the CO layer by forming different superstructures. The different CO structures induce strain and stress within the Cu surface and thus cause specific modifications of the electronic structure of the Cu. Oxygen adsorption, however, results in a more direct change in the Cu surface structure by the creation of vacancy clusters and CuO islands. (author)

  7. Adsorption of divalent copper, zinc, cadmium and lead ions from aqueous solution by waste tea and coffee adsorbents.

    Science.gov (United States)

    Djati Utomo, H; Hunter, K A

    2006-01-01

    The adsorption of the divalent cations of Cu, Zn, Cd and Pb by tea leaves and coffee grounds from aqueous solutions is described. Both adsorbents exhibited strong affinity for these ions which could be described by a simple single-site equilibrium model. For coffee, the order of increasing adsorption equilibrium constant K was Cu 10, probably because of anion formation in the case of Zn2+ and also increased leaching of metal-binding soluble materials. The effect of metal ion concentration on the adsorptive equilibria indicated a threshold concentration above which overall adsorption became limited by saturation of the adsorption sites. Competition between two metal ions for the same sites was not observed with Cu(II) and Pb(II), however Zn(II) reacted competitively with Cd(II) binding sites on both tea and coffee. If fresh coffee or tea adsorbents were used, the fraction of metal ion taken up by the adsorbent was diminished by the competitive effects of soluble metal-binding ligands released by the tea or coffee. Experiments with coffee showed that roasting temperature controls the formation of metal ion adsorption sites for this adsorbent.

  8. Rheology of Confined Polymer Melts under Shear Flow : Strong Adsorption Limit

    NARCIS (Netherlands)

    Subbotin, A.; Manias, E.; Hadziioannou, G.; Brinke, G. ten

    1995-01-01

    The dynamics of a confined polymer melt between strong adsorbing surfaces is considered theoretically. In particular the influence of bridging on the theological behavior is investigated. It is shown that the bridges are very important for small enough shear velocities. Several regimes of

  9. Lower critical field of an anisotropic type-II superconductor

    International Nuclear Information System (INIS)

    Klemm, R.A.; Clem, J.R.

    1980-01-01

    We consider the Ginzburg-Landau free energy of the anisotropic mass form in the presence of a magnetic field of arbitrary fixed direction. It is shown that the free energy may be transformed into the isotropic Ginsburg-Landau form with a kappa that depends upon the direction of the magnetic induction B relative to the crystal lattice. The lower critical field H/sub c/1 is then found for arbitrary direction of B. For highly anisotropic crystals the angular dependence of H/sub c/1 can exhibit a discontinuity or a cusp. The special case of a crystal with uniaxial symmetry is considered in detail

  10. Anisotropic extension of Finch and Skea stellar model

    Science.gov (United States)

    Sharma, Ranjan; Das, Shyam; Thirukkanesh, S.

    2017-12-01

    In this paper, the spacetime geometry of Finch and Skea [Class. Quantum Gravity 6:467, 1989] has been utilized to obtain closed-form solutions for a spherically symmetric anisotropic matter distribution. By examining its physical admissibility, we have shown that the class of solutions can be used as viable models for observed pulsars. In particular, a specific class of solutions can be used as an `anisotropic switch' to examine the impact of anisotropy on the gross physical properties of a stellar configuration. Accordingly, the mass-radius relationship has been analyzed.

  11. Anisotropic Liquid Microcapsules from Biomimetic Self-Folding Polymer Films.

    Science.gov (United States)

    Zakharchenko, Svetlana; Ionov, Leonid

    2015-06-17

    We demonstrated a novel approach for the fabrication of anisotropic capsules with liquid content using biomimetic self-folding thermoresponsive polymer films. The behavior of self-folding films is very similar to actuation in plants, where nonhomogenous swelling results in complex movements such as twisting, bending, or folding. This approach allows the design of anisotropic liquid capsules with rodlike and dumbbell-like morphologies. We found that these capsules are able to assemble into different complex structures, such as nematic-like one and 3D network depending on their morphology.

  12. Remarks on anisotropy of inertia in an anisotropic cosmos

    Science.gov (United States)

    Treder, Hans-Juergen

    1992-03-01

    The astronomical and physical meaning of the anisotropy of inertia is analyzed with respect to the relativity of inertia and anisotropic distributions of gravitating matter in the universe. Attention is given to the theoretical compatibility of the anisotropy of inertial masses with Mach's principle of the relativity of inertia and the Mach-Einstein doctrine of general relativity. Mach's principle does not imply anisotropy of inertial masses in an anisotropic universe, and the isotropy of cosmological mass is supported by the Mach-Einstein theories.

  13. Anisotropic behavior of quantum transport in graphene superlattices

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Cummings, Aron W.; Roche, Stephan

    2014-01-01

    We report on the possibility to generate highly anisotropic quantum conductivity in disordered graphene-based superlattices. Our quantum simulations, based on an efficient real-space implementation of the Kubo-Greenwood formula, show that in disordered graphene superlattices the strength of multi...... orders of magnitude, and suggesting the possibility of building graphene electronic circuits based on the unique properties of chiral massless Dirac fermions in graphene.......We report on the possibility to generate highly anisotropic quantum conductivity in disordered graphene-based superlattices. Our quantum simulations, based on an efficient real-space implementation of the Kubo-Greenwood formula, show that in disordered graphene superlattices the strength...

  14. All spherically symmetric charged anisotropic solutions for compact stars

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Raj Kumar Goel Institute of Technology, Department of Mathematics, Ghaziabad, UP (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India)

    2017-06-15

    In the present paper we develop an algorithm for all spherically symmetric anisotropic charged fluid distributions. Considering a new source function ν(r) we find a set of solutions which is physically well behaved and represents compact stellar models. A detailed study specifically shows that the models actually correspond to strange stars in terms of their mass and radius. In this connection we investigate several physical properties like energy conditions, stability, mass-radius ratio, electric charge content, anisotropic nature and surface redshift through graphical plots and mathematical calculations. All the features from these studies are in excellent agreement with the already available evidence in theory as well as observations. (orig.)

  15. Correlation theory of crystal field and anisotropic exchange effects

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1985-01-01

    A general theory for including correlation effects in static and dynamic properties is presented in terms of Raccah or Stevens operators. It is explicitly developed for general crystal fields and anisotropic interactions and systems with several sublattices, like the rare earth compounds. The the......A general theory for including correlation effects in static and dynamic properties is presented in terms of Raccah or Stevens operators. It is explicitly developed for general crystal fields and anisotropic interactions and systems with several sublattices, like the rare earth compounds...... on the susceptibility, the first and second moment frequencies and the line shape are calculated self-consistently....

  16. Tunable waveguide bends with graphene-based anisotropic metamaterials

    KAUST Repository

    Chen, Zhao-xian

    2016-01-15

    We design tunable waveguide bends filled with graphene-based anisotropic metamaterials to achieve a nearly perfect bending effect. The anisotropic properties of the metamaterials can be described by the effective medium theory. The nearly perfect bending effect is demonstrated by finite element simulations of various structures with different bending curvatures and shapes. This effect is attributed to zero effective permittivity along the direction of propagation and matched effective impedance at the interfaces between the bending part and the dielectric waveguides. We envisage that the design will be applicable in the far-infrared and terahertz frequency ranges owing to the tunable dielectric responses of graphene.

  17. Method of recovering adsorbed liquid compounds from molecular sieve columns

    Science.gov (United States)

    Burkholder, Harvey R.; Fanslow, Glenn E.

    1983-01-01

    Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed.

  18. Quantitative relationship between adsorbed amount of solute and solvent composition

    International Nuclear Information System (INIS)

    Wang Yan; Geng Xindu; Zebolsky, Don M.

    2003-01-01

    A new adsorption isotherm that relates the amount of solute adsorbed to the solvent concentration is proposed. The new equation is derived from Geng and Shi's stoichiometric displacement model for adsorption (SDM-A). The obtained equation may be simplified to an expression containing two parameters. The equation with two parameters, valid for low concentrations of solute, is a logarithmically linear relationship. The intercept contains a thermodynamic equilibrium constant of the solute displacing solvent from the adsorbent. The slope is the negative value of the stoichiometric displacement parameter (Z), the average total number of solvent molecules displaced from an active site on the adsorbent and from the solute. Tests with a homologous series of aromatic alcohols by frontal analysis in reversed phase liquid chromatography demonstrate that experimental results fit the equation well

  19. Lotus Dust Mitigation Coating and Molecular Adsorber Coating

    Science.gov (United States)

    O'Connor, Kenneth M.; Abraham, Nithin S.

    2015-01-01

    NASA Goddard Space Flight Center has developed two unique coating formulations that will keep surfaces clean and sanitary and contain contaminants.The Lotus Dust Mitigation Coating, modeled after the self-cleaning, water-repellant lotus leaf, disallows buildup of dust, dirt, water, and more on surfaces. This coating, has been successfully tested on painted, aluminum, glass, silica, and some composite surfaces, could aid in keeping medical assets clean.The Molecular Adsorber Coating is a zeolite-based, sprayable molecular adsorber coating, designed to prevent outgassing in materials in vacuums. The coating works well to adsorb volatiles and contaminates in manufacturing and processing, such as in pharmaceutical production. The addition of a biocide would also aid in controlling bacteria levels.

  20. Integral superposition of paraxial Gaussian beams in inhomogeneous anisotropic layered structures in Cartesian coordinates

    Czech Academy of Sciences Publication Activity Database

    Červený, V.; Pšenčík, Ivan

    2015-01-01

    Roč. 25, - (2015), s. 109-155 ISSN 2336-3827 Institutional support: RVO:67985530 Keywords : integral superposition of paraxial Gaussian beams * inhomogeneous anisotropic media * S waves in weakly anisotropic media Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  1. A new adsorbent for boron removal from aqueous solutions.

    Science.gov (United States)

    Kluczka, Joanna; Korolewicz, Teofil; Zołotajkin, Maria; Simka, Wojciech; Raczek, Malwina

    2013-01-01

    A new adsorbent based on natural clinoptilolite and amorphous zirconium dioxide (ZrO2) was prepared for the uptake of boron from fresh water. The sorption behaviour of this adsorbent for boron was investigated using a batch system and found to obey Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The ZrO2 loading level, pH, temperature, contact time, initial boron concentration and adsorbent dose, on the removal of boron were studied. It was found that the removal of boron increased while the adsorbent dose increased and the temperature decreased at an optimum pH (pH = 8) and a contact time of 30 min. At optimum conditions, the maximum boron percentage removal was 75%. According to the D-R model, the maximum capacity was estimated to be > 3 mg B/g of the adsorbent. The adsorption energy value (calculated as 9.13 kJ/mol) indicated that the adsorption of boron on clinoptilolite modified with ZrO2 was physical in nature. The parameters of the adsorption models and the pH investigations pointed to the possibility of a chemisorption process. The thermodynamic parameters (standard entropy deltaS degrees, enthalpy deltaH degrees , and free energy deltaG degrees changes) of boron adsorption were also calculated. The negative value of deltaS degrees indicated a decreased randomness at the solid-solution interface during the boron adsorption. Negative values of deltaH degrees showed the exothermic nature of the process. The negative values of deltaG degrees implied that the adsorption of boron on clinoptilolite modified with amorphous ZrO2 at 25 degrees C was spontaneous. It was considered that boron dissolved in water had been adsorbed both physically and chemically on clinoptilolite modified with 30% ZrO2.

  2. A Morphing framework to couple non-local and local anisotropic continua

    KAUST Repository

    Azdoud, Yan

    2013-05-01

    In this article, we develop a method to couple anisotropic local continua with anisotropic non-local continua with central long-range forces. First, we describe anisotropic non-local models based on spherical harmonic descriptions. We then derive compatible classic continuum models. Finally, we apply the morphing method to these anisotropic non-local models and present three-dimensional numerical examples to validate the efficiency of the technique. © 2013 Elsevier Ltd. All rights reserved.

  3. A model for sound propagation between two adsorbing microporous plates.

    Science.gov (United States)

    Nori, Massimiliano; Brandani, Stefano

    2014-05-01

    A model describing the sound propagation between two infinite adsorbing plates is proposed in order to investigate the extension to the audible sound range of the Frequency Response method applied to the measurement of diffusion in micropores. The model relates adsorption parameters (i.e., diffusivity and equilibrium constant) to an acoustic quantity (i.e., propagation constant). The equations describing sound propagation in the presence of adsorbing boundaries are obtained on the basis of the classical Kirchhoff theory [(1868). Ann. Phys. (Leipzig) 134, 177-193]. The solution is derived using the Low Reduced Frequency Approximation method [Tijdeman, (1975). J. Sound Vib. 39, 1-33].

  4. Hydrogen molecule on lithium adsorbed graphene: A DFT study

    International Nuclear Information System (INIS)

    Kaur, Gagandeep; Gupta, Shuchi; Gaganpreet; Dharamvir, Keya

    2016-01-01

    Electronic structure calculations for the adsorption of molecular hydrogen on lithium (Li) decorated and pristine graphene have been studied systematically using SIESTA code [1] within the framework of the first-principle DFT under the Perdew-Burke-Ernzerhof (PBE) form of the generalized gradient approximation (GGA)[2], including spin polarization. The energy of adsorption of hydrogen molecule on graphene is always enhanced by the presence of co-adsorbed lithium. The most efficient adsorption configuration is when H 2 is lying parallel to lithium adsorbed graphene which is in contrast to its adsorption on pristine graphene (PG) where it prefers perpendicular orientation.

  5. Removal of uranium by the adsorbents produced from coffee residues

    International Nuclear Information System (INIS)

    Mahramanlioglu, M.; Bicer, I.O.; Misirli, T.; Kilislioglu, A.

    2007-01-01

    Large amounts of coffee residues contaminate the environment and reprocessing of them as valuable products such as adsorbents will be a good solution from an environmental and economic point of view. In this study some adsorbents were produced from coffee residues and used for batch removal experiments of uranium from aqueous solutions. The adsorption kinetics was found to follow the Lagergren equation. The adsorption process was described with the Langmuir and Freundlich isotherms. Additionally, the effect of different cations on the adsorption of uranium was studied. (author)

  6. Electrochemical Studies of Paraquat Adsorbed onto Crystalline Apatite

    Directory of Open Access Journals (Sweden)

    Moulay Abderrahim EL MHAMMEDI

    2007-09-01

    Full Text Available The carbon paste electrode (CPE has been used to analyze the electrochemical behavior of paraquat (PQ adsorbed onto synthesized hydroxyapatite phosphocalcique (HAP in K2SO4 (0.1M. The cyclic voltammetry results obtained corrobate with square wave voltammetry. The influence of variables such as the concentration of paraquat adsorbed onto apatite (PQ/HAP, and the potential scan rate was tested.X-ray diffraction analysis (XRD, Fourier transformed infrared spectroscopy (FTIR analysis and inductively coupled plasma-atomic emission spectrometry (ICP, AES were used for characterization of the apatite.

  7. Wood microstructure explored by anisotropic 1H NMR line broadening: experiments and numerical simulations.

    Science.gov (United States)

    Terenzi, Camilla; Dvinskikh, Sergey V; Furó, István

    2013-07-18

    The cellular structure of wood, which is highly anisotropic along its main growth directions, is responsible for the observed anisotropy in its physical and mechanical properties that depend in a complex manner on the moisture content. Here, we demonstrate that the (1)H NMR spectra of wood from Norway spruce exhibit a strong and characteristic dependence on the direction of the sample relative to the applied magnetic field. By comparing spectra recorded at different magnetic-field strengths, we show that this variation is caused by the magnetic-field distribution created by the anisotropic and inhomogeneous distribution of matter and thereby magnetic susceptibility. On the basis of the observations that (i) the recorded spectral peak predominantly arises from translationally mobile water molecules and (ii) the spectral broadening is large if the long axis of the wood tracheid cells is perpendicular to the magnetic field, we set out to test the hypothesis that it is the susceptibility variation on the tracheid length scale that is responsible for the observed spectral features. To verify this, we numerically calculate in a discrete grid approximation the NMR line shapes obtained in realistic tracheid models, and we find that the calculated NMR line shapes are in good agreement with the corresponding experimental ones. We envisage the application of these findings for revealing the inhomogeneous distribution of water and its molecular properties in wood and wood-based materials at varying degrees of humidity.

  8. An in situ estimation of anisotropic elastic moduli for a submarine shale

    Science.gov (United States)

    Miller, Douglas E.; Leaney, Scott; Borland, William H.

    1994-11-01

    Direct arrival times and slownesses from wide-aperture walkaway vertical seismic profile data acquired in a layered anisotropic medium can be processed to give direct estimate of the phase slowness surface associated with the medium at the depth of the receivers. This slowness surface can, in turn, be fit by an estimated transversely isotropic medium with a vertical symmetry axis (a 'TIV' medium). While the method requires that the medium between the receivers and the surface be horizontally stratified, no further measurement or knowledge of that medium is required. When applied to data acquired in a compacting shale sequence (here termed the 'Petronas shale') encountered by a well in the South China Sea, the method yields an estimated TIV medium that fits the data extremely well over 180 deg of propagation angles sampled by 201 source positions. The medium is strongly anisotropic. The anisotropy is significantly anelliptic and implies that the quasi-shear mode should be triplicated for off-axis propagation. Estimated density-normalized moduli (in units of sq km/sq s) for the Petronas shale are A(sub 11) = 6.99 +/- 0.21, A(sub 33) = 5.53 +/- 0.17, A(sub 55) = 0.91 +/- 0.05, and A(sub 13) = 2.64 +/- 0.26. Densities in the logged zone just below the survey lie in the range between 2200 and 2400 kg/cu m with an average value close to 2300 kg/cu m.

  9. The structure and elastic moduli of flux-line lattices in anisotropic superconductors

    International Nuclear Information System (INIS)

    Grishin, A.M.; Martynovich, A.Yu.; Yampol'skiy, S.V.

    1992-01-01

    The elastic moduli of flux-line lattices in anisotropic superconductors are investigated. In addition to the well-known bulk, shear, and tilt moduli the authors observe moduli that relate deformations in the basal plane of the lattice to vortex tilt. These moduli vanish when the superconductor is magnetized along the axis of anisotropy. The vortex structure continuum realized in this case has identical bulk and shear moduli and different tilt moduli. A hexagonal flux-line lattice is realized in superconductors with 'easy axis' anisotropy when a weak magnetic field is applied. When the field H is applied in the ab-plane of the crystal the lattice becomes an oblique lattice with orthorhombic symmetry. This results in a sharp growth of its elastic moduli and the induction in the sample. Vortex chain structures are the only stable structures in 'easy plane' superconductors. The elastic moduli characterizing the rigidity of an isolated chain are exponentially large compared to the moduli describing interchain interaction. The tilt moduli may reverse their sign when H is oriented near the axis of anisotropy c for strongly anisotropic superconductors. In this case, the vortex structure and all related elastic moduli undergo a discontinuous irreversible change

  10. Transmission of terahertz radiation by anisotropic MWCNT/polystyrene composite films

    Energy Technology Data Exchange (ETDEWEB)

    Okotrub, A.V.; Bulusheva, L.G. [Nikolaev Institute of Inorganic Chemistry, SB RAS, 3 Acad. Lavrentiev Ave., 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 20 Karl Marx Ave., 630092 Novosibirsk (Russian Federation); Kubarev, V.V. [Budker Institute of Nuclear Physics, SB RAS, 11 Acad. Lavrentiev Ave., 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 2 Pirogova st., 630090 Novosibirsk (Russian Federation); Kanygin, M.A.; Sedelnikova, O.V. [Nikolaev Institute of Inorganic Chemistry, SB RAS, 3 Acad. Lavrentiev Ave., 630090 Novosibirsk (Russian Federation)

    2011-11-15

    Anisotropic composite materials have been prepared by repeated forge rolling of polystyrene and carbon nanotubes (CNTs) with length of {proportional_to}65 {mu}m. Transmission spectra of the composites were recorded for two different polarizations of the electric field. Obtained data indicated that the forge rolling resulted in a predominant orientation of CNTs in polymer matrix. Anisotropic response of the composites was measured at 130 {mu}m wavelength on the Novosibirsk terahertz free electron laser and angular dependence of the transmitted light was determined. Absorption spectrum showed no strong resonance features and it was interpreted by CNTs breaking and agglomeration of CNT fragments during the composite fabrication procedure. Based on classical theory of scattering, considered the scatters as electromagnetic antennas, the size distribution of CNTs in composites was found. Anisotropy of terahertz radiation transmitted from MWCNT/polystyrene composite film on the Novosibirsk free electron laser at 130 {mu}m wavelength. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. In-plane microwave dielectric properties of paraelectric barium strontium titanate thin films with anisotropic epitaxy

    Science.gov (United States)

    Simon, W. K.; Akdogan, E. K.; Safari, A.; Bellotti, J. A.

    2005-08-01

    In-plane dielectric properties of ⟨110⟩ oriented epitaxial (Ba0.60Sr0.40)TiO3 thin films in the thickness range from 25-1200nm have been investigated under the influence of anisotropic epitaxial strains from ⟨100⟩ NdGaO3 substrates. The measured dielectric properties show strong residual strain and in-plane directional dependence. Below 150nm film thickness, there appears to be a phase transition due to the anisotropic nature of the misfit strain relaxation. In-plane relative permittivity is found to vary from as much as 500-150 along [11¯0] and [001] respectively, in 600nm thick films, and from 75 to 500 overall. Tunability was found to vary from as much as 54% to 20% in all films and directions, and in a given film the best tunability is observed along the compressed axis in a mixed strain state, 54% along [11¯0] in the 600nm film for example.

  12. Development of polymeric adsorbents for recovery of uranium from seawater

    International Nuclear Information System (INIS)

    Britt, P.; Dai, S.; Hay, B.; Janke, C.; Mayes, R.; Saito, T.; Tsouris, C.; Rao, L.

    2014-01-01

    Extraction of uranium from unconventional resources, where uranium is in low concentrations as in seawater, can be orders of magnitude higher in cost than extraction from conventional sources. As a part of the Fuel Cycle Technology Research and Development Program in the United States Department of Energy, Office of Nuclear Energy, Oak Ridge National Laboratory (ORNL) is developing new adsorbents with higher capacities, selectivities, and durability for the cost effective extraction of uranium from seawater, the most challenging but highest-payoff unconventional resource. The ultimate goal is to develop a selective, high capacity, durable adsorbent that can economically extract uranium from seawater. Over the last three years, the key focus of the ORNL R&D efforts has been on increasing the adsorption capacity of amidoxime-based polymeric adsorbents by the radiation-induced graft polymerization on high surface-area polyethylene fiberous trunk materials. These trunk materials have been fabricated through an “islands-in-the-sea” fiber-spinning method, which can considerably enhance the surface area of the high-density polyethylene fibers without compromising its mechanical properties. Acrylonitrile and methacrylic acid can be effectively grafted onto these high surface-area fibers followed by conversion of the nitrile groups to amidoxime groups. Marine testing of these poly(acryamidoxime-co-methacrylic acid) adsorbents at the Pacific Northwest National Laboratory Marine Sciences Laboratory showed uranium adsorption capacities, for the extraction of uranium from seawater, that were more than three-times higher than that previously reported. We are continuing to work to increase the adsorbent capacities of the amidoxime-based adsorbents through optimization of the polymerization conditions and investigation of new grafting methods without the use of ionizing radiation such as Atom-Transfer Radical Polymerization. We have also successfully manufactured several

  13. Ray-optics analysis of inhomogeneous optically anisotropic media

    NARCIS (Netherlands)

    Sluijter, M.

    2010-01-01

    When the optical behavior of light in a medium depends on the direction in which light is traveling, the medium is called optically anisotropic. Light is an electromagnetic wave and in this thesis, we discuss the electromagnetic theory on optical anisotropy. We do this with the assumption that the

  14. On the origins of the anisotropic mechanical behaviour of extruded ...

    Indian Academy of Sciences (India)

    Mater. Sci., Vol. 40, No. 2, April 2017, pp. 395–406. c Indian Academy of Sciences. DOI 10.1007/s12034-017-1383-3. On the origins of the anisotropic mechanical behaviour of extruded. AA2017 aluminium alloy. A MAY. Laboratoire Génie des Matériaux, Ecole Militaire Polytechnique, BP 17, Bordj El Bahri 16046, Algeria.

  15. Negative index of refraction in anisotropic nonmagnetic materials

    Czech Academy of Sciences Publication Activity Database

    Dvořák, Vladimír; Kužel, Petr

    2006-01-01

    Roč. 338, - (2006), s. 195-203 ISSN 0015-0193 R&D Projects: GA AV ČR 1ET300100401 Institutional research plan: CEZ:AV0Z10100520 Keywords : anisotropic dielectric * negative refractive index * surface modes * guided modes Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.389, year: 2006

  16. Finite-difference modelling of anisotropic wave scattering in discrete ...

    Indian Academy of Sciences (India)

    A M Ekanem

    2018-04-05

    Apr 5, 2018 ... fractured hydrocarbon reservoirs to complement the use of other seismic attributes. Despite the con- certed effort in research and development related to seismic characterization of fractured reservoirs using anisotropic wave scattering, pragmatic uti- lization of this attribute in geophysical exploration.

  17. Autofocus imaging : Experimental results in an anisotropic austenitic weld

    NARCIS (Netherlands)

    Zhang, J.; Drinkwater, B.W.; Wilcox, P.D.; Hunter, A.J.

    2012-01-01

    The quality of an ultrasonic array image, especially for anisotropic material, depends on accurate information about acoustic properties. Inaccuracy of acoustic properties causes image degradation, e.g., blurring, errors in locating of reflectors and introduction of artifacts. In this paper, for an

  18. On the interpretation of time-resolved anisotropic diffraction patterns

    DEFF Research Database (Denmark)

    Lorenz, Ulf; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2010-01-01

    In this paper, we review existing systematic treatments for the interpretation of anisotropic diffraction patterns from partially aligned symmetric top molecules. Such patterns arise in the context of time-resolved diffraction experiments. We calculate diffraction patterns for ground-state Na...

  19. On the origins of the anisotropic mechanical behaviour of extruded ...

    Indian Academy of Sciences (India)

    This paper presents some experimental investigations about the origins of the anisotropic behaviour in cyclic loadings of AA2017 aluminium alloy. In the first step, fatigue damage evolutions were quantified for controlled proportional cyclic loadings in axial and shear directions. In this stage, the aim was to confirm the ...

  20. Anisotropic cosmological models and generalized scalar tensor theory

    Indian Academy of Sciences (India)

    Abstract. In this paper generalized scalar tensor theory has been considered in the background of anisotropic cosmological models, namely, axially symmetric Bianchi-I, Bianchi-III and Kortowski–. Sachs space-time. For bulk viscous fluid, both exponential and power-law solutions have been stud- ied and some assumptions ...

  1. Anisotropic cosmological models and generalized scalar tensor theory

    Indian Academy of Sciences (India)

    In this paper generalized scalar tensor theory has been considered in the background of anisotropic cosmological models, namely, axially symmetric Bianchi-I, Bianchi-III and Kortowski–Sachs space-time. For bulk viscous fluid, both exponential and power-law solutions have been studied and some assumptions among the ...

  2. Propagation of waves in a gravitating and rotating anisotropic heat ...

    African Journals Online (AJOL)

    Bheema

    (1956) equations neglecting the heat flux vector. Gravitational instability on propagation of magnetohydrodynamic (MHD) waves in astrophysical plasma is investigated by Alemayehu and Tessema (2013a) by considering the effect of gravitational instability and viscosity with anisotropic pressure tensor and heat conducting.

  3. Three anisotropic benchmark problems for adaptive finite element methods

    Czech Academy of Sciences Publication Activity Database

    Šolín, Pavel; Čertík, O.; Korous, L.

    2013-01-01

    Roč. 219, č. 13 (2013), s. 7286-7295 ISSN 0096-3003 R&D Projects: GA AV ČR IAA100760702 Institutional support: RVO:61388998 Keywords : benchmark problem * anisotropic solution * boundary layer Subject RIV: BA - General Mathematics Impact factor: 1.600, year: 2013

  4. Metastability thresholds for anisotropic bootstrap percolation in three dimensions

    NARCIS (Netherlands)

    Van Enter, A.C.D.; Fey, A.

    2012-01-01

    In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the

  5. Metastability Thresholds for Anisotropic Bootstrap Percolation in Three Dimensions

    NARCIS (Netherlands)

    Van Enter, A.C.D.; Fey, A.

    2012-01-01

    In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the

  6. Finite-size effects for anisotropic bootstrap percolation : Logarithmic corrections

    NARCIS (Netherlands)

    van Enter, Aernout C. D.; Hulshof, Tim

    In this note we analyse an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced by Duarte.

  7. Metastability Thresholds for Anisotropic Bootstrap Percolation in Three Dimensions

    NARCIS (Netherlands)

    Enter, Aernout C.D. van; Fey, Anne

    In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the

  8. Some dynamical properties of anisotropic collisionless stellar systems

    International Nuclear Information System (INIS)

    Bertin, G.; Pegoraro, F.

    1989-01-01

    The linear stability analysis of collisionless anisotropic spherical stellar systems presents many unresolved issues. Planning to study the stability of a simple and astrophysically interesting equilibrium seuence ∞ for such stellar systems, we describe here some analytical characterizations of the ∞-distribution functions, formulate the linearized equations for stability, and discuss the relevant boundary conditions. (author). 19 refs.; 1 tab

  9. New exact models for anisotropic matter with electric field

    Indian Academy of Sciences (India)

    Jefta M Sunzu

    2017-09-05

    Sep 5, 2017 ... In our models, we consider the stellar object that is anisotropic and charged with linear equation of state consistent with quark stars. ... Einstein–Maxwell equations; anisotropy; charged matter; equation of state. PACS Nos 04.20. .... Sunzu et al [3] which was a general cubic polynomial. However, our choice ...

  10. Wave propagation in a general anisotropic poroelastic medium ...

    Indian Academy of Sciences (India)

    equations (Auriault et al 1985) in terms of solid displacement and fluid pressure, whereas Biot's equations were in terms of displacements of both the solid and fluid phases. Homogenisation has proven that .... (8) to (10) imply that, in homogenisation approach, the anisotropic inertial coupling is hiding in the tensor {ˆρij}.

  11. Exact anisotropic sphere with polytropic equation of state

    Indian Academy of Sciences (India)

    Abstract. We study static spherically symmetric spacetime to describe compact objects with anisotropic matter distribution. We express the system of Einstein field equations as a new system of differential equations using a coordinate transformation, and then write the system in another form with polytropic equation of state ...

  12. Anisotropic Born-Mayer potential in lattice dynamics of Vanadium

    International Nuclear Information System (INIS)

    Onwuagba, B.N.

    1988-01-01

    A microscopic theory of the lattice dynamics of the transition metal vanadium is developed based on the Animalu's transition metal model potential (TMMP). The Born-Mayer potential associated with the distribution of the transition metal d-electrons is treated as anisotropic. Good agreement with experimental phonon dispersion curves longitudinal branches in the [111] direction

  13. Anisotropic strain and phonon deformation potentials in GaN

    International Nuclear Information System (INIS)

    Darakchieva, V.; Arwin, H.; Paskov, P. P.; Monemar, B.; Paskova, T.; Hommel, D.; Schubert, M.; Heuken, M.; Off, J.; Scholz, F.; Haskell, B. A.; Fini, P. T.; Speck, J. S.; Nakamura, S.

    2007-01-01

    We report optical phonon frequency studies in anisotropically strained c-plane- and a-plane-oriented GaN films by generalized infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The anisotropic strain in the films is obtained from high-resolution x-ray diffraction measurements. Experimental evidence for splitting of the GaN E 1 (TO), E 1 (LO), and E 2 phonons under anisotropic strain in the basal plane is presented, and their phonon deformation potentials c E 1 (TO) , c E 1 (LO) , and c E 2 are determined. A distinct correlation between anisotropic strain and the A 1 (TO) and E 1 (LO) frequencies of a-plane GaN films reveals the a A 1 (TO) , b A 1 (TO) , a E 1 (LO) , and b E 1 (LO) phonon deformation potentials. The a A 1 (TO) and b A 1 (TO) are found to be in very good agreement with previous results from Raman experiments [V. Yu. Davydov et al., J. Appl. Phys. 82, 5097 (1997)]. Our a A 1 (TO) and a E 1 (LO) phonon deformation potentials agree well with recently reported theoretical estimations [J.-M. Wagner and F. Bechstedt, Phys. Rev. B 66, 115202 (2002)], while b A 1 (TO) and b E 1 (LO) are found to be significantly larger than the theoretical values. A discussion of the observed differences is presented

  14. Double anisotropic electrically conductive flexible Janus-typed membranes.

    Science.gov (United States)

    Li, Xiaobing; Ma, Qianli; Tian, Jiao; Xi, Xue; Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Xinlu; Wang, Jinxian; Liu, Guixia

    2017-12-07

    Novel type III anisotropic conductive films (ACFs), namely flexible Janus-typed membranes, were proposed, designed and fabricated for the first time. Flexible Janus-typed membranes composed of ordered Janus nanobelts were constructed by electrospinning, which simultaneously possess fluorescence and double electrically conductive anisotropy. For the fabrication of the Janus-typed membrane, Janus nanobelts comprising a conductive side and an insulative-fluorescent side were primarily fabricated, and then the Janus nanobelts are arranged into parallel arrays using an aluminum rotary drum as the collector to obtain a single anisotropically conductive film. Subsequently, a secondary electrospinning process was applied to the as-prepared single anisotropically conductive films to acquire the final Janus-typed membrane. For this Janus-typed membrane, namely its left-to-right structure, anisotropic electrical conduction synchronously exists on both sides, and furthermore, the two electrically conductive directions are perpendicular. By modulating the amount of Eu(BA) 3 phen complex and conducting polyaniline (PANI), the characteristics and intensity of the fluorescence-electricity dual-function in the membrane can be tuned. The high integration of this peculiar Janus-typed membrane with simultaneous double electrically conductive anisotropy-fluorescent dual-functionality is successfully realized in this study. This design philosophy and preparative technique will provide support for the design and construction of new types of special nanostructures with multi-functionality.

  15. Anisotropic cosmological models in f (R, T) theory of gravitation

    Indian Academy of Sciences (India)

    Bianchi spaces are useful tools for constructing spatially homogeneous and anisotropic cosmological models in general relativity and scalar–tensor theories of gravitation. Adhav [14] obtained exact solutions of the field equations for LRS. Bianchi type-I space-time with perfect fluid in the framework of f (R, T) theory of grav-.

  16. Anisotropic Bianchi-I universe with phantom field and cosmological ...

    Indian Academy of Sciences (India)

    We study an anisotropic Bianchi-I universe in the presence of a phantom field and a cosmological constant. Cosmological solutions are obtained when the kinetic energy of the phantom field is of the order of anisotropy and dominates over the potential energy of the field. The anisotropy of the universe decreases and the ...

  17. Gmax for Sand by Bender Elements at Anisotropic Stress States

    DEFF Research Database (Denmark)

    Bødker, L.

    1996-01-01

    elements for two types of sand and with void ratios varying from minimum to maximum. The tests performed are carried out in the Danish Triaxial Cell, and Gmax are determined at different isotropic and anisotropic stress states. The main result of the test program is that Gmax is primarily influenced...

  18. Charged anisotropic star on paraboloidal space-time

    Indian Academy of Sciences (India)

    ... is the central pressure. At the boundary of the star r = R, pr must vanish, which gives r = R as the radius of the star. This form of radial pressure is prescribed by Sharma and Ratanpal [18] to describe anisotropic stellar model admitting a quadratic equation of state on paraboloidal space-time. Equations (8) and (4) give ν =.

  19. New exact models for anisotropic matter with electric field

    Indian Academy of Sciences (India)

    2017-09-05

    Sep 5, 2017 ... We can also obtain particular anisotropic models obtained by Maharaj, Sunzu, and Ray. The exact solutions corresponding to our models are found explicitly in terms of elementary functions. The graphical plots generated for the matter variables and the electric field are well behaved. We also generate ...

  20. Anisotropic colloids: bulk phase behavior and equilibrium sedimentation

    NARCIS (Netherlands)

    Marechal, M.A.T.

    2009-01-01

    This thesis focuses on the phase behavior of anisotropically shaped (i.e. non-spherical) colloids using computer simulations. Only hard-core interactions between the colloids are taken into account to investigate the effects of shape alone. The bulk phase behavior of three different shapes of